JP2000120471A - Cylinder injection type engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To activate catalyst in its early stage while discharge of unburnt fuel is being restrained by positively warming up exhaust gas purifying catalyst under a non-warming up state. SOLUTION: This device is equipped with exhaust gas purifying catalyst 11 provided for an exhaust gas passage 3, a fuel injection valve 5 directly injecting fuel into each cylinder, and with a fuel injection control means 17. The device is also provided with a temperature condition judging means 16 judging the temperature condition of the exhaust gas purifying catalyst 11. When it is determined by the temperature condition judging means 16 that exhaust gas purifying catalyst is in a low temperature condition in a non- warming up state, fuel is injected at least at a compression stroke, and when it is determined that exhaust gas purifying catalyst 11 is in a high temperature condition in a non-warming up state, the quantity of fuel injection made during the period of time from a suction stroke to a compression stroke, is so set up as to allow an air-fuel ratio in exhaust gas to be made leaner than a stoichiometric air-fuel ratio, so that fuel injection is so controlled as to be made in an expansion stroke.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a direct injection engine mounted on an automobile or the like.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Patent Application Laid-Open No. 4-231645, for example, a direct injection type internal combustion engine equipped with a lean NOx catalyst for purifying exhaust gas by adsorbing NOx in the exhaust gas. In the fuel injection timing control device, a sub-injection is performed separately from the main injection of the fuel, and the injection timing of the sub-injection is set within a period from the intake stroke to the compression stroke when the catalyst bed temperature is as low as 400 ° C. or less. Then, the catalyst bed temperature becomes higher than 400 ° C. and lean NOx
When the catalyst is completely warmed up and activated, the NOx purification rate of the catalyst is increased by setting it within the period from the latter half of the combustion period to the exhaust stroke.

That is, when the lean NOx catalyst is not warmed up, the injection timing control device causes the fuel of the sub-injection injected during the period from the intake stroke to the compression stroke to spread in the combustion chamber lean and partially burn. A residue is generated, and the unburned fuel is supplied to a lean NOx catalyst in a state where it is sufficiently thermally decomposed and partially oxidized in the compression, combustion and exhaust strokes, thereby increasing the NOx purification rate. ,
Further, after warming up the lean NOx catalyst, the sub-injection fuel injected during the period of the exhaust stroke from the latter half of the combustion stroke is supplied directly to the lean NOx catalyst almost without oxidizing, thereby increasing the catalyst bed temperature. Nevertheless, the configuration is such that the NOx purification rate is increased.

[0004]

The fuel injection timing control device described in the above publication discloses a fuel injection timing control system for controlling the sub-injection injected during the exhaust stroke from the latter half of the combustion stroke after the lean NOx catalyst is completely activated. Since the fuel is directly supplied to the catalyst, and when the lean NOx catalyst is not warmed up, the fuel is injected during the period from the intake stroke to the compression stroke. There is a problem that the catalyst in the warmed-up state cannot be activated effectively. That is, when the lean NOx catalyst is not warmed up, the injection timing of the sub-injection is set within the period from the intake stroke before the ignition timing to the compression stroke, and this fuel burns in the combustion stroke close to the compression top dead center. Since there is no combustion after the middle stage of the expansion stroke, there is a problem that the catalyst cannot be warmed up by burning the fuel in the exhaust stroke or close to the exhaust stroke.

As disclosed in Japanese Patent Application Laid-Open No. 9-79069, in an in-cylinder injection type catalyst activation control system in which fuel directly injected into a cylinder is fueled by spark ignition, an exhaust gas purifying catalyst is not used. In the active state, regardless of the temperature, a second fuel injection is performed in the first to middle stages of the expansion stroke, and this fuel is burned in the combustion chamber in the second half of the expansion stroke or the exhaust stroke, or in the exhaust passage. Although it is considered that the catalyst is activated by combusting the fuel, the injection fuel is sufficiently burned when the temperature of the exhaust gas purifying catalyst is low. There is a problem that it is discharged into the atmosphere in an unburned state without any combustion.

The present invention has been made in view of the above-described circumstances, and enables the exhaust gas purifying catalyst in an unwarmed state to be actively warmed up and activated early while suppressing discharge of unburned fuel. A control device for an internal injection engine is provided.

[0007]

The invention according to claim 1 is
In a control device for an in-cylinder injection engine including an exhaust gas purifying catalyst provided in an exhaust passage and a fuel injection valve for directly injecting fuel into a combustion chamber, a temperature state for determining a temperature state of the exhaust gas purifying catalyst. When it is determined by the determining means and the temperature state determining means that the exhaust gas purification catalyst is in the low temperature state in the unwarmed state, the fuel is injected at least in the compression stroke, and the exhaust gas purification catalyst is in the unwarmed state. Is determined to be in a high temperature state, the amount of fuel injected between the intake stroke and the compression stroke is set so that the air-fuel ratio in the exhaust gas is leaner than the stoichiometric air-fuel ratio, and expansion is performed. Fuel injection control means for controlling fuel injection during the stroke.

According to the above configuration, when it is determined that the exhaust gas purifying catalyst is in the low temperature state in the unwarmed state, the temperature of the exhaust gas is increased by the fuel injected in the compression stroke, so that the unburned state is maintained. The warm-up of the catalyst is promoted while preventing the discharge of fuel. If it is determined that the exhaust gas purifying catalyst is in a high temperature state in an unwarmed state, the amount of fuel injected between the intake stroke and the compression stroke depends on the air-fuel ratio in the exhaust gas and the stoichiometric air-fuel ratio. The fuel injected during the expansion stroke is subsequently burned in the combustion chamber or the exhaust passage in a state where the excess oxygen is sufficiently secured by setting to be leaner than the unburned fuel. Thus, the warm-up of the catalyst is further effectively promoted while preventing the discharge of the catalyst.

According to a second aspect of the present invention, in the control apparatus for a direct injection type engine according to the first aspect, when it is determined that the exhaust gas purifying catalyst is not in a warm-up state, an empty space in the exhaust gas is determined. The fuel ratio is controlled so as to be leaner than 13.

According to the above configuration, when the exhaust gas purifying catalyst is not warmed up, the air-fuel ratio in the exhaust gas is controlled to be leaner than 13, so that sufficient combustion can be achieved. Unburned fuel is effectively prevented from being discharged to the exhaust passage in a low temperature state of the exhaust gas purification catalyst, while the exhaust gas temperature is raised and the fuel consumption is prevented from being deteriorated due to the injection of more fuel than necessary. Will be.

According to a third aspect of the present invention, in the control device for a direct injection type engine according to the first aspect, when it is determined that the exhaust gas purifying catalyst is in a low temperature state in a non-warm-up state, the exhaust gas purifying catalyst is provided. The air-fuel ratio is controlled so as to be in the range of 13 to 16.

According to the above configuration, when the exhaust gas purifying catalyst is in a low temperature state in an unwarmed state, the air-fuel ratio in the exhaust gas is controlled so as to be in a range of 13 to 16. The air-fuel ratio becomes unnecessarily rich, which prevents the exhaust gas temperature from lowering due to latent heat of vaporization of the fuel, or prevents deterioration of combustion due to lack of oxygen, and prevents deterioration of fuel efficiency and discharge of unburned fuel to the exhaust passage. . Further, the air-fuel ratio does not become unnecessarily lean and the combustibility does not deteriorate, and the decrease in the exhaust gas temperature is suppressed.

According to a fourth aspect of the present invention, in the control apparatus for a direct injection type engine according to the third aspect, when it is determined that the exhaust gas purifying catalyst is in a high temperature state in a non-warmed state, the exhaust gas purification catalyst may be used. The air-fuel ratio is controlled so as to be in the range of 13 to 16.

According to the above configuration, when the exhaust gas purifying catalyst is in a high temperature state in an unwarmed state, the air-fuel ratio in the exhaust gas is controlled so as to be within a range of 13 to 16. This prevents the fuel efficiency from deteriorating due to the air-fuel ratio becoming richer than necessary, and preventing the exhaust gas from cooling due to the air-fuel ratio becoming leaner than necessary.

According to a fifth aspect of the present invention, there is provided the control apparatus for a direct injection engine according to the first aspect, further comprising an O ₂ sensor for detecting an air-fuel ratio in the exhaust gas. the control apparatus of the formula engine, after activation of the O ₂ sensor, and feedback control of the fuel injection amount so that the air-fuel ratio of the exhaust gas based on the output value of the O ₂ sensor becomes the stoichiometric air-fuel ratio .

According to the above configuration, the control for setting the air-fuel ratio in the exhaust gas to the stoichiometric air-fuel ratio based on the output value of the O ₂ sensor in a state where the unburned fuel is prevented from being discharged to the exhaust passage. It is executed properly with high accuracy, the flammability and the like are maintained in a good state, and the exhaust gas temperature can be effectively raised.

According to a sixth aspect of the present invention, in the control apparatus for a direct injection type engine according to any one of the first to third aspects or the fifth aspect, the exhaust gas purifying catalyst has a low temperature in an unwarmed state. When it is determined that the vehicle is in the state, the fuel is divided into an intake stroke and a compression stroke and fuel is injected.

According to the above configuration, in the low temperature state of the exhaust gas purifying catalyst in the unwarmed state, the fuel injected in the intake stroke into the cylinder during the middle load or high load operation of the engine with a large fuel injection amount. A uniform mixture is formed,
The concentration of the mixture in the cylinder is varied by the fuel injected in the compression stroke, or a mixture with a relatively rich air-fuel ratio is formed around the spark plug, ensuring sufficient ignitability or initial combustion. At the same time, the second half combustion becomes slow, and the exhaust gas temperature rises effectively.

According to a seventh aspect of the present invention, in the control apparatus for a direct injection type engine according to any one of the first to third aspects or the fifth aspect, the exhaust gas purifying catalyst has a low temperature in an unwarmed state. When it is determined that the vehicle is in the state, the fuel is injected separately into the first half of the compression stroke and the second half of the compression stroke.

According to the above configuration, in the low temperature state of the exhaust gas purifying catalyst in the unwarmed state, the fuel is excessively diffused around the ignition plug during a low load operation of an engine having a relatively small fuel injection amount. Thus, an appropriate mixture in the lean state is formed around the surroundings, and the exhaust gas temperature is effectively increased while maintaining good combustion.

According to an eighth aspect of the present invention, in the control apparatus for a direct injection type engine according to any one of the first to third aspects or the fifth aspect, the exhaust gas purifying catalyst has a low temperature in an unwarmed state. When it is determined that the fuel cell is in the state, the fuel is collectively injected in the compression stroke.

According to the above configuration, in a low temperature state where the exhaust gas purifying catalyst is not warmed up, excessive diffusion of the fuel around the spark plug is effectively prevented during an idling operation or the like where the fuel injection amount is considerably small. Thus, the flammability is maintained in a better condition.

According to a ninth aspect of the present invention, in the control apparatus for a direct injection type engine according to the first or second aspect, it is determined that the exhaust gas purifying catalyst is in a high temperature state in an unwarmed state. In addition, fuel is divided into a compression stroke and an expansion stroke to inject fuel.

According to the above configuration, the fuel injected in the compression stroke forms a rich air-fuel mixture around the ignition plug by the fuel injected in the compression stroke, for example, during idling in a low temperature state when the exhaust gas purification catalyst is not warmed up. As a result, the ignitability is ensured, and the temperature of the exhaust gas is effectively increased by the fuel injected in the expansion stroke, so that the warm-up of the exhaust gas purifying catalyst is promoted.

According to a tenth aspect of the present invention, in the control apparatus for a direct injection type engine according to the first or second aspect, it is determined that the exhaust gas purifying catalyst is in a high temperature state in an unwarmed state. In addition, fuel is divided into an intake stroke and an expansion stroke to inject fuel.

According to the above structure, when the exhaust gas purifying catalyst is not warmed up and the engine is in a high temperature state and the engine is under medium load or high load operation, uniform combustion is performed in a state where the fuel injected in the intake stroke is uniformly diffused. By doing so, the engine output is ensured and the warm-up of the exhaust gas purifying catalyst is promoted by the fuel injected during the expansion stroke.

According to an eleventh aspect of the present invention, in the control apparatus for a direct injection engine according to the first or second aspect, it is determined that the exhaust gas purifying catalyst is in a high temperature state in an unwarmed state. In addition, the intake stroke, the compression stroke,
The fuel is injected separately into the expansion stroke.

According to the above configuration, when the exhaust gas purifying catalyst is not warmed up and the engine is running at a low load in a high temperature state or the like, the fuel injected in the compression stroke mixes a rich air-fuel ratio around the ignition plug. Gas is formed to ensure ignitability, and a fuel-fuel mixture injected in the intake stroke forms a lean mixture around it and performs slow combustion, effectively raising the exhaust gas temperature. The warm-up of the exhaust gas purifying catalyst is promoted by the fuel injected in the expansion stroke.

The twelfth aspect of the present invention is directed to the sixth aspect.
9. The control device for a direct injection engine according to claim 8, wherein when it is determined that the exhaust gas purifying catalyst is in a high temperature state in a non-warmed state, the exhaust gas purifying catalyst is in a non-warmed state. In addition to fuel injection at low temperatures,
The additional injection of fuel is performed in the expansion stroke.

According to the above configuration, when the exhaust gas purifying catalyst shifts from a low temperature state to a high temperature state in an unwarmed state,
Since the fuel injected during the expansion stroke is sufficiently combusted in the exhaust passage or the combustion chamber without causing a sudden change in the operating state, the warm-up of the catalyst is effectively promoted.

According to a thirteenth aspect of the present invention, in the control apparatus for a direct injection type engine according to the eighth aspect, when it is determined that the exhaust gas purifying catalyst is in a high temperature state in a non-warmed state, the exhaust gas purifying method is performed. In addition to fuel injection in a low temperature state when the purification catalyst is not warmed up, additional injection of fuel is performed in the expansion stroke, and the fuel amount of this additional injection is set to be equal to or less than the fuel injected before ignition. Control so that the

According to the above configuration, when the exhaust gas purifying catalyst is not warmed up and transitions from a low temperature state to a high temperature state,
The fuel injected in the expansion stroke is easily combusted and burns in the exhaust passage or the like without causing a sudden change in the operating state and deterioration of fuel efficiency, thereby effectively promoting warm-up of the catalyst. Will be.

According to a fourteenth aspect of the present invention, in the control device for a direct injection engine according to the sixth or seventh aspect, it is determined that the exhaust gas purifying catalyst is in a high temperature state in a non-warmed state. In addition, in addition to fuel injection in a low temperature state when the exhaust gas purification catalyst is not warmed up, additional injection of fuel is performed in the expansion stroke, and the fuel amount of this additional injection is calculated from the fuel amount injected before ignition. Is also controlled so as to reduce the number of times.

According to the above configuration, when the exhaust gas purifying catalyst is not warmed up and transitions from a low temperature state to a high temperature state,
While the sudden change of the operating state and the deterioration of the fuel economy are effectively prevented, the fuel injected in the expansion stroke becomes easily combusted and burns in the exhaust passage or the like, thereby effectively warming up the catalyst. Will be promoted.

According to a fifteenth aspect of the present invention, there is provided a control device for a direct injection type engine including an exhaust gas purifying catalyst provided in an exhaust passage and a fuel injection valve for directly injecting fuel into a combustion chamber. Temperature state determining means for determining the temperature state of the gas purification catalyst, and when the temperature state determining means determines that the exhaust gas catalyst is in a non-warmed state,
In an operation region of a predetermined load or less of the engine, fuel is divided and injected into an intake stroke and a compression stroke, and in an operation region on a higher load side than the above operation region, the air-fuel ratio in the exhaust gas is smaller than the stoichiometric air-fuel ratio. And a fuel injection control means for controlling to inject fuel in a divided manner into a compression stroke and an expansion stroke under a lean condition.

According to the above configuration, when the engine is not warmed up while the exhaust gas purifying catalyst is in a low-to-medium load state, a uniform mixture is formed in the cylinder by the fuel injected in the intake stroke. The concentration of the air-fuel mixture in the cylinder is varied by the injected fuel, or a mixture having a relatively rich air-fuel ratio is formed around the ignition plug, thereby ensuring sufficient ignitability or initial flammability. Then, the combustion in the latter half becomes slow and the exhaust gas temperature rises effectively. Further, in the high-load operation region of the engine when the exhaust gas purifying catalyst is not warmed up in which the exhaust gas temperature tends to increase, the fuel is divided into the compression stroke and the expansion stroke, and the fuel is injected into the high-load side. Due to the increase in the combustion gas temperature and the excess oxygen, the combustibility in the expansion stroke is enhanced, and the discharge of unburned fuel is prevented, and the warm-up of the catalyst is effectively promoted. .

The invention according to claim 16 is the invention according to claim 15.
In the control device for a direct injection engine described in the above, in the high load side operation region, the fuel injection amount in the compression stroke is set such that the air-fuel ratio in the exhaust gas is leaner than the stoichiometric air-fuel ratio. is there.

According to the above configuration, in the operating region on the high load side of the engine in the unwarmed state of the exhaust gas purifying catalyst in which the exhaust gas temperature tends to increase, the excess oxygen promotes the combustion in the expansion stroke. The exhaust gas temperature can be further increased.

The invention according to claim 17 is the invention according to claim 15.
17. The control device for a direct injection engine according to claim 16, wherein in the high-load operation region, control is performed such that fuel is divided into a first half of a compression stroke, a second half of a compression stroke, and an expansion stroke to inject fuel. Things.

According to the above configuration, in the operating range on the high load side of the engine when the exhaust gas purifying catalyst is not warmed up in which the gas temperature tends to rise, the first half of the compression stroke, the second half of the compression stroke, and the expansion stroke By injecting the fuel separately, warming up of the catalyst is further effectively promoted.

The invention according to claim 18 is directed to a control device for a direct injection type engine including an exhaust gas purifying catalyst provided in an exhaust passage and a fuel injection valve for directly injecting fuel into a combustion chamber. A temperature state determining means for determining a temperature state of the gas purifying catalyst; and, when the temperature state determining means determines that the exhaust gas purifying catalyst is not in the warm-up state, the intake stroke and the compression in the low engine speed region of the engine. While dividing and injecting the fuel into the stroke, in the operating region on the higher rotation side than the low rotation region of the engine, the fuel is divided into the expansion stroke and the period from the intake stroke to the compression stroke, and the fuel is injected.
And a fuel injection control means for controlling the injection so that the amount of fuel injected between the intake stroke and the compression stroke becomes leaner than the stoichiometric air-fuel ratio in the exhaust gas.

According to the above configuration, in the low rotation region of the engine when the exhaust gas purifying catalyst is not warmed up, the fuel is divided into the intake stroke and the compression stroke, and the fuel is injected.
The fuel injected in the intake stroke forms a uniform mixture in the cylinder, the fuel injected in the compression stroke varies the concentration of the mixture in the cylinder, or a relatively rich air space around the spark plug. A mixture of fuel ratios is formed to ensure sufficient ignitability or initial flammability, and the second half combustion is slowed down, thereby effectively increasing the exhaust gas temperature. Also, in the high-speed operation region of the engine in an unwarmed state of the exhaust gas purifying catalyst in which the exhaust gas temperature tends to increase, the compression stroke is performed so that the air-fuel ratio in the exhaust gas is leaner than the stoichiometric air-fuel ratio. And the expansion stroke is injected into the fuel, so that the combustion gas temperature rise due to the high rotation speed where the number of combustions per unit time is high and the excess oxygen increase the combustibility in the expansion stroke, and The warm-up of the catalyst is effectively promoted while preventing the emission of unburned fuel.

According to a nineteenth aspect of the present invention, there is provided a control apparatus for a direct injection type engine including an exhaust gas purifying catalyst provided in an exhaust passage and a fuel injection valve for directly injecting fuel into a combustion chamber. Temperature state determining means for determining the temperature state of the gas purifying catalyst; and when the temperature state determining means determines that the exhaust gas purifying catalyst is in a low temperature state in an unwarmed state, fuel is injected at least in a compression stroke. When it is determined that the exhaust gas purifying catalyst is in a high temperature state in an unwarmed state, the expansion and contraction between the intake stroke and the compression stroke is performed under the condition that the air-fuel ratio in the exhaust gas is leaner than 13. Fuel injection control means for controlling to inject fuel by dividing the exhaust gas into a stroke, and activating the exhaust gas purifying catalyst when it is determined that the catalyst is in a high temperature state in an unwarmed state. It is obtained by a secondary air supply means for supplying secondary air for.

According to the above configuration, when it is determined that the exhaust gas purifying catalyst is in the low temperature state in the unwarmed state,
Since the temperature of the exhaust gas is increased by the fuel injected in the compression stroke, the warm-up of the catalyst is promoted while the discharge of the unburned fuel is prevented. Further, when the exhaust gas purifying catalyst is in a high temperature state in an unwarmed state, the secondary air supplied from the secondary air supply means causes combustion of fuel injected in an expansion stroke in an exhaust passage or the like. This further promotes warming-up of the catalyst while preventing unburned fuel from being discharged.

The invention according to claim 20 is the invention according to claim 19.
In the in-cylinder injection engine control device described above, when it is determined that the exhaust gas purification catalyst is in the high temperature state in the unwarmed state, the exhaust gas by the fuel injection before ignition is smaller than in the low temperature state. When the air-fuel ratio in the gas is controlled to be high, and when it is determined that the exhaust gas purifying catalyst is in a low temperature state in an unwarmed state, the ignition timing control means sets the ignition timing by a predetermined amount than the MBT. In addition to retarding the ignition timing, when it is determined that the exhaust gas purification catalyst is in the high temperature state in the unwarmed state, the ignition timing is controlled to be advanced to the MBT side as compared with the low temperature state.

According to the above configuration, when the exhaust gas purifying catalyst is in a low temperature state in an unwarmed state, the ignition timing is retarded by a predetermined amount from the MBT by the ignition timing control means, so that the exhaust gas purification catalyst is exhausted. The temperature rises and the warm-up of the catalyst is effectively promoted. Further, when the exhaust gas purifying catalyst shifts from a low temperature state to a high temperature state in an unwarmed state, the ignition timing is advanced to the MBT side as compared with the low temperature state, thereby suppressing an increase in the total fuel injection amount. As a result, deterioration of fuel efficiency is prevented.

According to a twenty-first aspect of the present invention, there is provided a control apparatus for a direct injection type engine including an exhaust gas purifying catalyst provided in an exhaust passage and a fuel injection valve for directly injecting fuel into a combustion chamber. Starting state determining means for determining whether the engine is in a starting state, catalyst state determining means for determining whether the exhaust gas purifying catalyst is in an active state, and determining that the engine is in a starting state by the starting determining means. In this case, the first injection mode in which fuel is injected only during the intake stroke is set, and when the catalyst determination unit determines that the catalyst is not warmed up after the engine is started, a predetermined period of time set in advance is set. Is a second injection mode in which fuel is dividedly injected during a period from an intake stroke to a compression stroke, and a later injection timing is set to a compression stroke. It is obtained by a fuel injection control means for controlling the ignition timing so that the third injection mode for injecting fuel is divided into a stroke and the expansion stroke.

According to the above configuration, the fuel is injected only during the intake stroke when the engine is started, so that the mixture is uniform and the startability of the engine is ensured. By split injection of fuel during the period from the intake stroke to the compression stroke, the exhaust gas temperature rises and the warm-up of the catalyst is promoted. Further, at a point in time when a predetermined time has elapsed after the start of the engine, a transition is made to a third injection mode in which fuel is divided into a compression stroke and an expansion stroke, and fuel injected in the expansion stroke is burned in the exhaust passage. By doing so, the warm-up of the catalyst is more effectively promoted while preventing the emission of unburned fuel.

The invention according to claim 22 is the invention according to claim 21.
In the control device for an in-cylinder injection engine described above, the injection amount of the fuel in the first injection mode to be injected before ignition is made larger than that in the second injection mode, and the fuel injection in the second injection mode is performed. The amount is controlled to be larger than that in the third injection mode.

According to the above configuration, when the engine is started,
Since the mixture is made relatively rich, the startability of the engine is ensured, and immediately after the start of the engine, the amount of fuel that can increase the exhaust gas temperature and promote the warm-up of the catalyst is provided. Is injected. Further, at a point in time when a predetermined time has elapsed after the start of the engine, the fuel mixture injected into the expansion stroke is prevented from being discharged in an unburned state by making the air-fuel mixture relatively lean, The warm-up of the catalyst will be promoted more effectively.

According to the twenty-third aspect of the present invention,
23. The control device for a direct injection type engine according to claim 22, wherein the ignition timing in the second injection mode is retarded by a predetermined amount from the MBT, and the ignition timing in the third injection mode is set to the second injection mode. It is provided with an ignition timing control means for controlling so as to advance to the MBT side as compared with the injection mode.

According to the above configuration, the ignition timing is retarded by a predetermined amount from the MBT immediately after the start of the engine, so that the exhaust gas temperature rises and the warm-up of the catalyst is effectively promoted. At the same time, when a predetermined time has elapsed after the start of the engine, the ignition
By advancing to the side, torque reduction due to the air-fuel ratio being controlled to the lean state is suppressed.

According to a twenty-fourth aspect of the present invention, there is provided a control apparatus for a direct injection type engine having an exhaust gas purifying catalyst provided in an exhaust passage and a fuel injection valve for directly injecting fuel into a combustion chamber. Temperature state determining means for determining the temperature state of the gas purification catalyst; and, when the temperature state determination means determines that the exhaust gas purification catalyst is in the low temperature state in the unwarmed state, the temperature from the intake stroke to the ignition timing is determined. If the exhaust gas purifying catalyst is determined to be in a high temperature state in the unwarmed state when the exhaust gas purification catalyst is subjected to a temperature increase control to increase the exhaust gas temperature during the period between the intake stroke and the ignition timing. Fuel injection control means for setting the amount of fuel to be injected so as to be leaner than the stoichiometric air-fuel ratio and controlling fuel injection in an expansion stroke after ignition.

According to the above configuration, when it is determined that the exhaust gas purifying catalyst is in a low temperature state in which the exhaust gas purifying catalyst is not warmed up, the fuel injection is performed from the intake stroke to the ignition timing, and the exhaust gas purifying catalyst is performed. Temperature increase control for increasing the temperature of the catalyst is performed. Further, when it is determined that the exhaust gas purifying catalyst is in a high temperature state in a non-warmed state, the amount of fuel injected between the intake stroke and the ignition timing becomes leaner than the stoichiometric air-fuel ratio. Is set to, the fuel injected in the expansion stroke after ignition in a state where the excess oxygen is sufficiently secured burns in the combustion chamber or the exhaust passage, thereby suppressing the emission of unburned fuel. Meanwhile, warming up of the catalyst is further effectively promoted.

The invention according to claim 25 is the above-mentioned claim 24.
When it is determined that the exhaust gas purification catalyst is in a high temperature state in which the exhaust gas purification catalyst is not warmed up, the control device controls the ignition timing to be retarded by a predetermined amount from the MBT. It is provided with ignition timing control means.

According to the above configuration, when the exhaust gas purifying catalyst is in a high temperature state in an unwarmed state, the ignition timing is retarded by a predetermined amount from the MBT by the ignition timing control means. The temperature rises, and the warm-up of the exhaust gas purifying catalyst is effectively promoted.

The invention according to claim 26 is the invention according to claim 25.
In the control device for a direct injection type engine described above, when the control for retarding the ignition timing by a predetermined amount from the MBT is executed, control is performed so that fuel injection is performed at least in the intake stroke.

According to the above configuration, when the exhaust gas purifying catalyst is in a high temperature state in a non-warmed state, a uniform mixture is formed in the cylinder by the fuel injected in the intake stroke, and the ignition timing is increased. The ignition timing is set to MB by the control means.
By retarding by a predetermined amount from T, the exhaust gas temperature rises and the warm-up of the exhaust gas purifying catalyst is effectively promoted while maintaining the good combustibility.

According to the twenty-seventh aspect, the twenty-fourth aspect is provided.
In the in-cylinder injection engine control device described above, when it is determined that the exhaust gas purification catalyst is in a high temperature state in the unwarmed state, by variably controlling the fuel injection amount injected in the expansion stroke, The air-fuel ratio in the exhaust gas is repeatedly changed between a rich state and a lean state.

According to the above configuration, when the exhaust gas purifying catalyst is in a high temperature state in an unwarmed state, the air-fuel ratio in the exhaust gas is variably controlled by controlling the fuel injection amount injected in the expansion stroke. Repeatedly changes between the rich state and the lean state, and the oxygen stored in the catalyst in the lean state and the excess fuel supplied in the rich state properly react to prevent the discharge of the unburned fuel and the exhaust gas. The warm-up of the gas purification catalyst is effectively promoted.

The invention according to claim 28 is the invention according to claim 27.
In the control device for an in-cylinder injection engine described above, the air-fuel ratio in the exhaust gas can be varied between the rich state and the lean state by variably controlling the fuel injection amount in the expansion stroke between each cylinder of the engine having a plurality of cylinders. And it is configured to change repeatedly.

According to the above configuration, when the exhaust gas purifying catalyst is in a high temperature state in an unwarmed state, the amount of fuel injected during the expansion stroke is variably controlled among the cylinders, so that the exhaust gas The medium air-fuel ratio repeatedly changes between the rich state and the lean state, and the oxygen stored in the catalyst in the lean state and the excess fuel supplied in the rich state properly react, thereby preventing the emission of unburned fuel. At the same time, the warm-up of the exhaust gas purifying catalyst is effectively promoted.

The invention according to claim 29 is the invention according to claim 27.
In the control apparatus for an in-cylinder injection engine described above, the air-fuel ratio in the exhaust gas can be varied between the rich state and the lean state by variably controlling the fuel injection amount during the expansion stroke in the same cylinder of an engine having a plurality of cylinders. And it is configured to change repeatedly.

According to the above configuration, when the exhaust gas purifying catalyst is in a high temperature state in a non-warmed state, the amount of fuel injected during the expansion stroke is variably controlled in the same cylinder, so that the exhaust gas The medium air-fuel ratio repeatedly changes between the rich state and the lean state, and the oxygen stored in the catalyst in the lean state and the excess fuel supplied in the rich state properly react, thereby preventing the emission of unburned fuel. At the same time, the warm-up of the exhaust gas purifying catalyst is effectively promoted.

The invention according to claim 30 is the invention according to claim 28.
Or the control device for a direct injection engine according to the item 29, wherein the air-fuel ratio in the exhaust gas is repeatedly changed between a rich state and a lean state by intermittently executing the fuel injection in the expansion stroke. Things.

According to the above configuration, when the exhaust gas purifying catalyst is in a high temperature state in an unwarmed state, the fuel injection amount in the expansion stroke is intermittently performed between the cylinders or in the same cylinder. The air-fuel ratio in the exhaust gas repeatedly changes between a rich state and a lean state, and the oxygen stored in the catalyst in the lean state properly reacts with the excess fuel supplied in the rich state, and the unburned fuel is discharged. Be prevented,
The warm-up of the exhaust gas purifying catalyst is effectively promoted.

The invention according to claim 31 is the invention according to claim 24.
In the in-cylinder injection engine control device described above, when it is determined that the exhaust gas purification catalyst is in a high temperature state in an unwarmed state, the air-fuel ratio in the exhaust gas is set to be in a range of 14 to 17. To control.

According to the above configuration, when the exhaust gas purifying catalyst is in a high temperature state in an unwarmed state, the air-fuel ratio in the exhaust gas is controlled so as to be within a range of 14 to 17. This prevents the fuel efficiency from deteriorating due to the air-fuel ratio becoming richer than necessary, and preventing the exhaust gas from cooling due to the air-fuel ratio becoming leaner than necessary.

The invention according to claim 32 is the invention according to claim 24.
In the in-cylinder injection engine control device described above, when it is determined that the exhaust gas purifying catalyst is in a low temperature state in an unwarmed state, the ignition timing is retarded by a predetermined amount from the MBT, so that the exhaust gas is exhausted. It is configured to execute temperature increase control for increasing the temperature.

According to the above configuration, when the exhaust gas purifying catalyst is in a low temperature state in an unwarmed state, the ignition timing is retarded by a predetermined amount from the MBT, so that the exhaust gas temperature rises quickly. As a result, the warm-up of the exhaust gas purifying catalyst is effectively promoted.

The invention according to claim 33 is the invention according to claim 24.
In the in-cylinder injection engine control device described above, when it is determined that the exhaust gas purification catalyst is in a low temperature state in the unwarmed state, the fuel is injected at least in the compression stroke, and the fuel injection timing is set to the temperature. It is configured such that the angle is advanced more than during the stratified operation or during the warm stratified operation.

According to the above configuration, when the exhaust gas purifying catalyst is in a low temperature state in the unwarmed state, a relatively rich air-fuel mixture is formed around the ignition plug by the fuel injected in the compression stroke. The fuel injection timing is set to the same or advanced angle as during warm stratification operation,
Unnecessarily rich air-fuel mixture is prevented from being formed around the ignition plug, and vaporization and atomization of the fuel are appropriately promoted. Thereby, the ignitability is maintained, and the rise of the exhaust gas temperature is promoted.

The invention according to claim 34 is the invention according to claim 24.
In the control device of the direct injection engine described, when it is determined that the exhaust gas purification catalyst is in a low temperature state in the unwarmed state, while injecting fuel at least in the compression stroke, this compression stroke injection, This is configured to end the compression process before 3/4 of the compression stroke has elapsed.

According to the above configuration, since the fuel injection is completed before the elapse of 3/4 of the compression stroke, the formation of an unnecessarily rich air-fuel mixture around the ignition plug is prevented. The vaporization and atomization of the fuel will be moderately promoted.

The invention according to claim 35 is the invention according to claim 24.
The control apparatus for an in-cylinder injection engine according to claim 1, further comprising a valve-opening overlap amount varying means for varying an overlap amount between the intake valve and the exhaust valve, wherein the exhaust gas purification catalyst is in a low temperature state in an unwarmed state. Is determined, the valve opening overlap amount is reduced.

According to the above configuration, when the exhaust gas purifying catalyst is in a low temperature state in an unwarmed state, the amount of overlap between the intake valve and the exhaust valve is set to be small and the internal EGR
By reducing the amount, the exhaust gas temperature is effectively raised, and when the exhaust gas purifying catalyst is in a high temperature state in an unwarmed state, a large overlap amount between the intake valve and the exhaust valve is set. As a result, the internal EGR amount is increased, so that the vaporization and atomization of the fuel are promoted, the combustion efficiency is improved, and the discharge of the unburned fuel is suppressed.

The invention according to claim 36 is the invention according to claim 24.
In the in-cylinder injection engine control device described above, when it is determined that the exhaust gas purification catalyst is in a low temperature state in an unwarmed state, the air-fuel ratio in the exhaust gas is adjusted to be in a range of 14 to 17. Thus, the temperature increase control for increasing the exhaust gas temperature is executed.

According to the above configuration, when the exhaust gas purifying catalyst is in the low temperature state in the unwarmed state, the air-fuel ratio in the exhaust gas is adjusted so as to be within the range of 14 to 17. The air-fuel ratio becomes unnecessarily rich, which prevents the exhaust gas temperature from lowering due to latent heat of vaporization of the fuel, or prevents deterioration of combustion due to lack of oxygen, and prevents deterioration of fuel efficiency and discharge of unburned fuel to the exhaust passage. . In addition, the temperature increase control that raises the temperature of the exhaust gas purification catalyst is appropriately executed without preventing the air-fuel ratio from becoming leaner than necessary and deteriorating the combustibility and suppressing the decrease in the exhaust gas temperature. Will be.

The invention according to claim 37 is the invention according to claim 31.
Or the control device for a direct injection engine according to 36, further comprising an O ₂ sensor for detecting an air-fuel ratio in the exhaust gas,
By performing feedback control of the fuel injection amount based on the output value of the O ₂ sensor, the air-fuel ratio in the exhaust gas becomes 1
It is configured to be in the range of 4 to 17.

According to the above configuration, the control for setting the air-fuel ratio in the exhaust gas within the range of 14 to 17 based on the output value of the O ₂ sensor can be properly executed with high accuracy.

According to a thirty-eighth aspect of the present invention, there is provided a control device for a direct injection type engine including an exhaust gas purifying catalyst provided in an exhaust passage and a fuel injection valve for directly injecting fuel into a combustion chamber. A temperature state determining means for determining a temperature state of the gas purification catalyst; and a temperature state determining means for determining that the exhaust gas purification catalyst has become inactive due to a decrease in the temperature of the exhaust gas purification catalyst during the stratified lean operation. In this case, the amount of fuel injected between the intake stroke and the ignition timing is set so that the in-cylinder air-fuel ratio is leaner than the stoichiometric air-fuel ratio, and fuel is injected during the expansion stroke after ignition. And a fuel injection control means for performing control as described above.

According to the above configuration, during stratified lean operation,
If the exhaust gas purifying catalyst is deactivated due to a decrease in the temperature of the exhaust gas purifying catalyst, the amount of fuel injected between the intake stroke and the ignition timing is leaner than the stoichiometric air-fuel ratio. By setting so that the excess oxygen is sufficiently secured, the fuel injected in the expansion stroke after ignition burns in the combustion chamber or the exhaust passage, thereby discharging the unburned fuel. Is suppressed, and the reactivation of the catalyst is effectively promoted.

The invention according to claim 39 is the invention according to claim 38.
In the in-cylinder injection engine control device described above, when it is determined that the exhaust gas purifying catalyst is in an inactive state, the fuel injection amount injected in the expansion stroke is variably controlled to thereby control the amount of exhaust gas contained in the exhaust gas. The air-fuel ratio is configured to be repeatedly changed between a rich state and a lean state.

According to the above configuration, during stratified lean operation,
When the exhaust gas purifying catalyst becomes inactive due to a decrease in the temperature of the exhaust gas purifying catalyst, the air-fuel ratio in the exhaust gas is controlled by variably controlling the amount of fuel injected during the expansion stroke. Repeatedly changes between the rich state and the lean state, and the oxygen stored in the catalyst in the lean state and the excess fuel supplied in the rich state properly react to prevent the discharge of the unburned fuel and the exhaust gas. Reactivation of the gas purification catalyst is effectively promoted.

The invention according to claim 40 is the invention according to claim 38.
In the control device of the in-cylinder injection engine described, when it is determined that the exhaust gas purification catalyst is in an inactive state,
The air-fuel ratio in the exhaust gas is controlled so as to be in the range of 14 to 17.

According to the above configuration, during stratified lean operation,
When the exhaust gas purifying catalyst becomes inactive due to a decrease in the temperature of the exhaust gas purifying catalyst, the air-fuel ratio in the exhaust gas is adjusted to be in the range of 14 to 17, The air-fuel ratio becomes unnecessarily rich, which prevents the exhaust gas temperature from lowering due to latent heat of vaporization of the fuel, or prevents deterioration of combustion due to lack of oxygen, and prevents deterioration of fuel efficiency and discharge of unburned fuel to the exhaust passage. . In addition, the control for raising the temperature of the exhaust gas purifying catalyst and activating it while preventing the air-fuel ratio from becoming leaner than necessary and deteriorating the combustibility and suppressing the decrease in the exhaust gas temperature is properly performed. Will be executed.

The invention according to claim 41 is the invention according to claim 38.
The in-cylinder injection engine control device according to claim 1, further comprising an O ₂ sensor that detects an air-fuel ratio in the exhaust gas, and performing a feedback control of a fuel injection amount based on an output value of the O ₂ sensor to obtain an exhaust gas. Are set so that the air-fuel ratio is within the range of 14 to 17.

According to the above configuration, during stratified lean operation,
When the exhaust gas purifying catalyst becomes inactive due to a decrease in the temperature of the exhaust gas purifying catalyst, the air-fuel ratio in the exhaust gas falls within a range of 14 to 17 based on the output value of the O ₂ sensor. The control to be performed is properly executed with high accuracy.

The invention according to claim 42 is directed to a control device for a direct injection type engine including an exhaust gas purifying catalyst provided in an exhaust passage and a fuel injection valve for directly injecting fuel into a combustion chamber. Temperature state determining means for determining the temperature state of the gas purifying catalyst; and, when the temperature state determining means determines that the exhaust gas purifying catalyst is not in the warm-up state, between the intake stroke and the ignition timing, Fuel injection control for performing fuel injection by dividing into an expansion stroke after ignition and increasing the amount of fuel injection during the expansion stroke when the exhaust gas purification catalyst is not warmed up in a high temperature state compared to when the exhaust gas purification catalyst is in a low temperature state. Means.

According to the above configuration, when it is determined that the exhaust gas purifying catalyst is not yet warmed up, the fuel injection is divided into the period from the intake stroke to the ignition timing and the expansion stroke after the ignition. As a result, the fuel injected during the expansion stroke is burned in the combustion chamber or the exhaust passage, so that the warm-up of the exhaust gas purifying catalyst is promoted. When the temperature of the exhaust gas purifying catalyst is low in the unwarmed state, the amount of fuel injected in the expansion stroke after ignition is set to be small, so that the emission of unburned fuel is suppressed, and the exhaust gas purifying catalyst is discharged. At a high temperature in an unwarmed state, a large amount of fuel is injected during the expansion stroke after ignition, so that a large amount of fuel is burned in the combustion chamber or the exhaust passage, thereby further warming up the catalyst. It will be effectively promoted.

[0091]

FIG. 1 shows an embodiment of a control device for a direct injection engine according to the present invention. The control device of the direct injection engine includes an intake passage 2 and an exhaust passage 3 connected to an engine main body 1 of a direct injection gasoline engine mounted on an automobile;
And a fuel injection valve 5 for directly injecting fuel into the combustion chamber.

A surge tank 6 is provided in the intake passage 2 and a throttle valve 7 is provided upstream of the surge tank 6. The throttle valve 7 is configured to be driven by an electric actuator 9 that operates in accordance with a control signal output from an engine control unit (ECU) 8 to adjust the amount of intake air.

The exhaust passage 3 is provided with an O ₂ sensor 10 for detecting the air-fuel ratio of the exhaust gas and an exhaust gas purifying catalyst 11 for purifying the exhaust gas. The exhaust gas purification catalyst 11 may be constituted by a three-way catalyst,
In order to enhance the purification performance when the air-fuel ratio is lean and the stratified operation is performed after warm-up, a catalyst that can effectively purify NOx even when the air-fuel ratio is leaner than the stoichiometric air-fuel ratio is used. It is desirable to use.

The engine includes an air flow sensor 12 for detecting an amount of intake air flowing through the intake passage 2, a crank angle sensor 13 for detecting an engine speed, an accelerator opening sensor 14, an engine water temperature sensor 15, and the like. These sensors are provided, and these detection signals are input to the engine control unit 8. The engine control unit 8 includes a temperature state determination unit 16 for determining a temperature state of the exhaust gas purification catalyst 11, a fuel injection control unit 17 for controlling a fuel injection amount and an injection timing, and an ignition timing for controlling an ignition timing. Control means 18 is provided.

The temperature state determination means 16 estimates the temperature state of the exhaust gas purification catalyst 11 according to, for example, a detection signal of the engine water temperature sensor 15, and thereby the warm-up state in which the exhaust gas purification catalyst 11 is activated And if it is determined that the exhaust gas purification catalyst 11 is not warmed up, the exhaust gas purification catalyst 11 is further in a low temperature state immediately after the start of the engine, or It is configured to determine whether or not the engine is in a high temperature state where a predetermined time has elapsed after the start of the operation. Note that the temperature state of the exhaust gas purification catalyst 11 is determined based on the detection value of the engine water temperature sensor 15 and the lapse of time from the start of the engine, or the temperature of the exhaust gas purification catalyst 11 is directly detected. Thus, the temperature state may be determined.

The fuel injection control means 17 is set in advance on the basis of the accelerator opening detected by the accelerator opening sensor 14 for detecting the accelerator opening and the engine speed detected by the crank angle sensor 15. The target torque of the engine from the map
Based on the target torque and the actual intake air amount detected by the air flow sensor 7, a target fuel injection amount is read from a preset map, and a control signal corresponding to the target fuel injection amount is transmitted to the fuel injection valve 5. Is configured to be output.

Further, the fuel injection control means 17 is configured to control the fuel injection timing according to the operating state of the engine. That is, when starting the engine,
By promoting the vaporization and atomization of the fuel and improving the combustibility, in order to secure the startability of the engine, control is performed to collectively inject the fuel in the intake stroke to perform uniform combustion. I have.

When the temperature state determining means 16 determines that the exhaust gas purifying catalyst 11 is not yet warmed up after the engine is started, the engine operating region and the temperature state of the exhaust gas purifying catalyst 11 are determined. Is configured to execute the control according to. That is, as shown in FIG. 2, when the engine is in the high-load, high-speed operation region A, the control is performed such that the fuel is injected collectively in the intake stroke to perform uniform combustion.

On the other hand, in the operating range B in which the engine is at a low rotation speed with a low load, a medium load and a low rotation speed, the temperature state determination means 16 determines whether or not the exhaust gas purification catalyst 11 is in a low temperature state. When it is determined that the engine is in a low temperature state, the fuel is injected separately into an intake stroke and a compression stroke. As a result, combustion is sequentially propagated from the vicinity of the ignition plug 4 to the periphery thereof in a state where a relatively rich air-fuel mixture exists near the ignition plug 4 and a relatively lean air-fuel mixture exists around the ignition plug 4. As a result, the so-called after-burning of fuel is promoted, the exhaust gas temperature rises, and the warm-up of the exhaust gas purifying catalyst 11 is promoted.

If it is determined that the exhaust gas purifying catalyst 11 is in a high temperature state in a non-warmed state in the operating range B where the engine is at a low rotation speed with a low load, the engine has a stoichiometric air-fuel ratio in the exhaust gas. Under the condition that the fuel ratio is leaner, after performing early injection of fuel in the compression stroke, control is performed to perform late injection of fuel in the expansion stroke, and the fuel injected in the compression stroke performs stratified combustion. The fuel injected during the expansion stroke is burned in the exhaust passage 3 or the like in a state where the excess oxygen is sufficiently secured, so that the unburned fuel is prevented from being discharged. It will be effectively promoted.

Further, when the temperature state determining means 16 determines that the exhaust gas purifying catalyst 11 is in a warm-up state, injection timing control is executed according to the operating range of the engine, as shown in FIG. Meanwhile, when the engine is in the high-load high-speed operation region C, control is performed so as to perform uniform injection by collectively injecting fuel in the intake stroke, and when the engine is in the low-load low-speed operation region D, The control is executed to perform stratified combustion by collectively injecting fuel in the compression stroke.

The ignition timing control means 18 is configured to control the ignition timing so that the required minimum ignition advance (MBT) at which the maximum shaft torque can be obtained, in principle, according to the operating state of the engine. I have. When it is determined that the exhaust gas purifying catalyst 11 is in a low temperature state in the unwarmed state, the ignition timing control means 18 retards the ignition timing by a predetermined amount from the MBT,
If it is determined that the exhaust gas purifying catalyst 11 is in a high temperature state in an unwarmed state, control is performed to advance the ignition timing to the MBT side as compared to the low temperature state, that is, the retard amount is reduced, or The control for setting to 0 is performed.

The basic control operation of the control unit for a direct injection engine will be described with reference to the flowchart shown in FIG. When the control operation is started, first, each detection signal of the air flow sensor 7, the accelerator opening sensor 14, and the crank angle sensor 15 is read (Step S).
1) Based on the starter switch signal or the engine speed, the start determination means 19 determines whether or not the engine is being started (step S2). As a result of this determination, when it is confirmed that the engine is being started, the fuel injection timing is controlled so that the fuel is injected at a time during the intake stroke (step S3).

If NO is determined in step S2, and if it is determined that the engine is in the state after starting, the temperature state determination means 16 determines whether the exhaust gas purification catalyst 11 is in a not-warmed state. Is determined (step S4), and Y
If determined to be ES, it is determined whether or not the engine is in the low / medium load / low rotation region B (step S5). If NO is determined in this step S5 and it is confirmed that the engine is in the high-load and high-speed region A, the process proceeds to step S3, and the fuel injection timing is set so that the fuel is injected at one time in the intake stroke. Control.

If the result of the determination in step S5 is YES, and it is confirmed that the engine is in the low-medium-load low-speed range B, the temperature state determination means 16 sets the exhaust gas purification catalyst 11 to a low temperature state. It is determined whether or not the exhaust gas purification catalyst 11 is in a low temperature state in a non-warm-up state (YES in step S6), and is divided into an intake stroke and a compression stroke. Fuel is injected (step S7).

On the other hand, if NO is determined in step S6 and it is determined that the exhaust gas purifying catalyst 11 is in a high temperature state in an unwarmed state, fuel is divided into a compression stroke and an expansion stroke and fuel is injected. (Step S8).

If NO is determined in step S4 and it is determined that the exhaust gas purifying catalyst 11 is in a warm-up state, it is determined whether or not the engine is in a high-load high-speed region C (step S4). Step S9). In this step S9, Y
If it is determined as ES and it is confirmed that the engine is in the high-load and high-speed region C, the process proceeds to step S3 to control the fuel injection timing so as to collectively inject fuel during the intake stroke. If NO is determined in step S9 and it is confirmed that the engine is in the low-load low-speed range D, the fuel injection timing is controlled so that the fuel is injected at once in the compression stroke (step S10).

When the temperature state determination means 16 determines that the exhaust gas purification catalyst 11 is in the low temperature state in the unwarmed state as described above, fuel is divided into an intake stroke and a compression stroke, and fuel is injected. When it is determined that the exhaust gas purifying catalyst 11 is in a high temperature state in a non-warmed state, the amount of fuel injected between the intake stroke and the expansion stroke is adjusted so that the air-fuel ratio in the exhaust gas is leaner than the stoichiometric air-fuel ratio. And the fuel injection is performed in the expansion stroke, so that the exhaust gas purification catalyst 11 in the unwarmed state is actively warmed while suppressing the discharge of the unburned fuel. It can be activated early.

That is, when it is determined that the exhaust gas purifying catalyst 11 is in the low temperature state in the unwarmed state, the fuel is injected in the compression stroke by dividing the fuel into the intake stroke and the compression stroke. A relatively rich mixture is formed in the vicinity of the ignition plug 4 in a state where the concentration of the mixture in the cylinder is varied by the fuel, and a relatively lean mixture is formed around the ignition plug 4 by the fuel injected in the intake stroke. By forming an air-fuel mixture and sequentially propagating the combustion from the vicinity of the spark plug 4 to the periphery thereof, the latter half of the combustion is slowed down.
The so-called afterburning of fuel can be promoted.

Therefore, as shown by the dashed line b or the dashed line c in FIG. 5B, when the fuel is injected all at once during the intake stroke from the time T1 after the start to the time T2 after a predetermined time has elapsed. In comparison, as shown by the solid line a in FIG. 5B, the exhaust gas temperature can be sharply increased from the start time T1, and the warm-up of the exhaust gas purification catalyst 11 can be promoted.

When it is determined that the exhaust gas purifying catalyst 11 is in the high temperature state in the unwarmed state, the air-fuel ratio in the exhaust gas becomes leaner than the stoichiometric air-fuel ratio by the compression stroke injection as described above. The fuel is injected in the expansion stroke while the excess oxygen is sufficiently secured by setting as described above, so that the temperature of the exhaust gas can be sufficiently increased, and the exhaust gas purifying catalyst in a high temperature state can be used. 1
By burning the exhaust gas purifying catalyst 11 at the installation portion 1 or the like, the warm-up of the exhaust gas purifying catalyst 11 can be further effectively promoted.

Therefore, the dashed line c in FIGS.
As shown by a solid line a in FIGS. 5B to 5D, as compared with a case in which the fuel is collectively injected in the intake stroke even after the time T2 when the exhaust gas purification catalyst 11 shifts to the high temperature state.
As shown by, the exhaust gas temperature can be effectively increased to quickly activate the exhaust gas purification catalyst 11, and the HC purification rate can be effectively increased.
Emissions of components can be effectively reduced.

On the other hand, as shown by the alternate long and short dash line b in FIGS. 5 (B) to 5 (D), batch injection of fuel is performed in the intake stroke until a predetermined time T2 elapses from the time T1 after the start. In the above configuration, when the control state is shifted to the control state of injecting fuel in the compression stroke and the expansion stroke at the predetermined time T2, the exhaust gas purification catalyst 11 is sufficiently heated. Since the fuel is injected during the expansion stroke in a state in which the fuel cannot be discharged, the fuel cannot be effectively burned at the installation portion of the exhaust gas purification catalyst 11 or the like, and a large amount of the HC component is discharged to the outside. Will be.

If it is determined that the exhaust gas purifying catalyst 11 is not warmed up, the combustion is divided into the intake stroke and the compression stroke in the low temperature state, and the compression stroke is divided in the high temperature state. It is desirable to control the air-fuel ratio in the exhaust gas determined by the fuel divided and injected into the expansion stroke so that the air-fuel ratio is leaner than 13, and in such a configuration, it is more than necessary. In addition, it is possible to prevent deterioration of fuel efficiency due to the injection of the fuel, and prevent deterioration of emission due to discharge of unburned fuel to the exhaust passage 3 when the exhaust gas purification catalyst 11 is in a low temperature state.

Further, when it is determined that the exhaust gas purifying catalyst 11 is in a low temperature state in an unwarmed state, the air-fuel ratio in the exhaust gas is controlled to be within a range of 13 to 16. In this case, it is possible to prevent the fuel efficiency from deteriorating due to the air-fuel ratio becoming richer than necessary, and to prevent the unburned fuel from being discharged into the exhaust passage 3, thereby preventing the deterioration of the emission. However, there is an advantage that it is possible to prevent the combustion property from becoming unnecessarily lean and to deteriorate the combustibility, and to prevent a decrease in the exhaust gas temperature due to the cooling of the exhaust gas by excess air (oxygen).

Further, when it is determined that the exhaust gas purifying catalyst 11 is in the high temperature state in the unwarmed state, the air-fuel ratio in the exhaust gas is controlled to be in the range of 13 to 16. In this case, there is an advantage that it is possible to prevent the air-fuel ratio from becoming richer than necessary and the fuel efficiency from deteriorating, and to prevent the air-fuel ratio from becoming leaner than necessary and cooling the exhaust gas.

Further, O ₂ for detecting the air-fuel ratio in the exhaust gas is used.
After the sensor 10 is activated, the fuel injection amount may be feedback-controlled based on the output value of the O ₂ sensor 10 so that the air-fuel ratio in the exhaust gas becomes the stoichiometric air-fuel ratio. In the case of such a configuration, the air-fuel ratio in the exhaust gas is determined based on the output value of the O ₂ sensor 10 so as to prevent the unburned fuel from being discharged into the exhaust passage 3 and secure the combustibility. Is appropriately and accurately executed with high accuracy, and the exhaust gas temperature can be effectively increased while maintaining a proper combustion state.

In the above embodiment, when it is determined that the exhaust gas purifying catalyst 11 is in a low temperature state in the unwarmed state, the fuel is divided into an intake stroke and a compression stroke to inject fuel. Although the above description has been made, the present invention is not limited to this, and the fuel may be injected at least in the compression stroke in the low temperature state.

For example, when the exhaust gas purification catalyst 11 is not warmed up and the engine is operating under a low load in a low temperature state, the fuel is divided into the first half of the compression stroke and the second half of the compression stroke to inject fuel. In such a case, the fuel mixture is prevented from excessively diffusing around the spark plug 4 and the surrounding air-fuel mixture is set to an appropriate lean state so that the fuel injection amount is relatively small. Even during the low load operation, the exhaust gas temperature can be effectively increased while maintaining good combustion.

Further, when the exhaust gas purifying catalyst 11 is idling at a low temperature in an unwarmed state, etc.
When it is determined that the exhaust gas purification catalyst 11 is in the low temperature state in the unwarmed state, the fuel may be collectively injected in the compression stroke. While effectively preventing the fuel from excessively diffusing around the spark plug 4, the surrounding air-fuel mixture is set to an appropriate lean state, and the combustion performance is improved during an idling operation with a considerably small fuel injection amount. be able to.

Further, in the above embodiment, when it is determined that the exhaust gas purifying catalyst 11 is in a high temperature state in a non-warmed state, the fuel is divided into a compression stroke and an expansion stroke to inject fuel. Therefore, when the engine is idling, the fuel injected in the compression stroke forms a rich air-fuel mixture around the ignition plug 4 to ensure ignitability. There is an advantage that the temperature of the exhaust gas can be effectively increased and the warm-up of the exhaust gas purifying catalyst 11 can be promoted.

The timing of the early injection when executing the split injection when the exhaust gas purifying catalyst 11 is in a high temperature state in an unwarmed state is not limited to the above-described compression stroke. In the load or high load operation region, the fuel may be injected separately into the intake stroke and the expansion stroke. In the case of such a configuration, the fuel injected in the intake stroke is uniformly diffused and uniformly burned, so that the engine output can be secured and the exhaust gas purification catalyst 11 can be secured by the fuel injected in the expansion stroke. Can effectively promote warm-up.

Further, when the exhaust gas purification catalyst 11 is not warmed up and the engine is operating under a low load in a high temperature state, the fuel is divided into an intake stroke, a compression stroke, and an expansion stroke to inject fuel. May be. With this configuration, the fuel injected in the compression stroke forms a rich air-fuel mixture around the ignition plug 4 to ensure ignitability, and the intake stroke is formed around the ignition plug 4. A lean mixture is formed by the fuel injected in the step (1) to perform slow combustion, thereby effectively increasing the exhaust gas temperature, and warming up the exhaust gas purification catalyst 11 by the fuel injected in the expansion stroke. Can be promoted.

Further, in the above-described structure in which the fuel injection timing is changed according to the operating state of the engine, the exhaust gas purification catalyst 11 is changed to a low temperature state in which the exhaust gas purification catalyst 11 is not warmed up. When it is determined that the temperature of the exhaust gas purifying catalyst has reached the high temperature state in the unwarmed state, the exhaust gas purification catalyst performs the additional injection of the fuel in the expansion stroke in addition to the fuel injection in the low temperature state in the unwarmed state. You may comprise. In such a configuration, when the exhaust gas purification catalyst 11 is not warmed up and transitions from a low-temperature state to a high-temperature state, it is possible to effectively prevent a sudden change in the operating state from occurring, and to prevent the sudden change in the operating state during the expansion stroke. By sufficiently burning the injected fuel in the exhaust passage 3 or the like, the warm-up of the catalyst 11 can be effectively promoted.

Further, as described above, the exhaust gas purifying catalyst 11
Is configured to inject fuel in the compression stroke in a batch when it is determined that the exhaust gas purification catalyst 11 is in the low temperature state in the unwarmed state, the exhaust gas purification catalyst 11 is in the high temperature state in the unwarmed state. When it is determined that, in addition to the fuel injection in the low temperature state when the exhaust gas purification catalyst is not warmed up, additional injection of fuel is performed in the expansion stroke, and the injection amount of this additional fuel is changed before ignition. It is desirable to control so as to be equal to or less than the injected fuel.

According to the above configuration, the exhaust gas purifying catalyst 11
Is not warmed up, and when the state shifts from the low temperature state to the high temperature state, the fuel injected in the expansion stroke is easily combusted in the exhaust passage 3 or the like without causing a sudden change in the operating state and deterioration in fuel efficiency. By sufficiently burning, the warm-up of the catalyst 11 can be effectively promoted.

Further, as described above, the exhaust gas purifying catalyst 1
If it is determined that the fuel cell 1 is in the low temperature state in the unwarmed state, the fuel is divided into the intake stroke and the compression stroke to inject fuel, or the fuel is divided into the first half of the compression stroke and the second half of the compression stroke to inject fuel. When the exhaust gas purification catalyst 11 is determined to be in the high temperature state in the unwarmed state, the fuel injection in the low temperature state in the unwarmed state is performed. In addition, while performing additional injection of fuel in the expansion stroke, the fuel amount of this additional injection is
It is desirable to control the fuel amount to be smaller than the amount of fuel injected before ignition.

According to the above configuration, the exhaust gas purifying catalyst 11
When the engine is not warmed up and transitions from a low-temperature state to a high-temperature state, the exhaust passage is set as a state in which the fuel injected in the expansion stroke is easily combusted while effectively preventing sudden changes in the operating state and deterioration of fuel efficiency. By burning enough in 3 etc.
The warm-up of the catalyst 11 can be effectively promoted.

The fuel injection timing is controlled in accordance with the operating range of the engine instead of the above-described embodiment in which the fuel injection timing is controlled in accordance with the temperature state of the exhaust gas purification catalyst 11 which is not warmed up. May be controlled.
That is, when it is determined that the exhaust gas catalyst 11 is in the operating range below the predetermined load of the engine in the unwarmed state, the fuel is divided and injected into the intake stroke and the compression stroke, and In the operation range on the higher load side than the range, the fuel is injected in the compression stroke and then injected in the expansion stroke so that the air-fuel ratio in the exhaust gas is leaner than the stoichiometric air-fuel ratio. You may.

According to the above configuration, the exhaust gas purifying catalyst 11
In a low-medium load region of an engine having a relatively small fuel injection amount in a non-warmed state, the fuel is divided into an intake stroke and a compression stroke, and fuel is injected. A uniform air-fuel mixture is formed, and the air-fuel mixture in the cylinder is enriched by the fuel injected in the compression stroke to form a rich air-fuel mixture around the ignition plug 4, thereby providing ignitability or initial ignition. In addition to ensuring sufficient combustibility, the exhaust gas temperature can be effectively increased. Further, in an operating region on the high load side of the engine in an unwarmed state of the exhaust gas purifying catalyst 11 in which the exhaust gas temperature tends to increase, the air-fuel ratio in the exhaust gas is set to be leaner than the stoichiometric air-fuel ratio. After the fuel is injected in the compression stroke, the fuel is injected in the expansion stroke to increase the temperature of the combustion gas due to the high load side and the excess oxygen to increase the combustibility in the expansion stroke, and to increase the unburned fuel. It is possible to effectively promote the warm-up of the catalyst 11 while preventing the discharge of the catalyst.

Further, in an operation region on the high load side of an engine having a large fuel injection amount, the fuel injection amount in the compression stroke is set so that the air-fuel ratio in the exhaust gas is leaner than the stoichiometric air-fuel ratio. According to this configuration, the fuel injected in the compression stroke in the high-load region of the engine in the unwarmed state of the exhaust gas purifying catalyst 11 in which the exhaust gas temperature tends to increase may be supplied with excess oxygen. Thus, the warm-up of the catalyst 11 can be effectively promoted. In particular, in a case where the fuel injection is performed in the first half of the compression stroke and the second half of the compression stroke in the operation region on the high load side, control is performed to inject fuel in the expansion stroke. Since the exhaust temperature can be further raised by promoting the combustion in the process, the warm-up of the catalyst 11 can be further effectively promoted.

When the temperature state determining means 16 determines that the exhaust gas purifying catalyst is not warmed up, the fuel is divided into the intake stroke and the compression stroke in the low engine speed region of the engine and injected. At the same time, in the operating region on the high rotation side of the engine, the fuel is injected between the intake stroke and the compression stroke so that the air-fuel ratio in the exhaust gas is leaner than the stoichiometric air-fuel ratio. You may comprise so that fuel may be injected.

According to the above configuration, the exhaust gas purifying catalyst 11
When the engine is running at a low speed in an unwarmed state, the fuel is dividedly injected into the intake stroke and the compression stroke, so that the fuel injected in the compression stroke has a relatively rich air-fuel mixture around the spark plug 4. Is formed so that the ignitability can be ensured, and the fuel injected in the intake stroke forms a lean air-fuel mixture around the fuel cell and slowly burns the mixture, thereby effectively raising the exhaust gas temperature. Further, in an operating region on the high rotation side of the engine in an unwarmed state of the exhaust gas purification catalyst 11 in which the exhaust gas temperature tends to increase, the air-fuel ratio in the exhaust gas is leaner than the stoichiometric air-fuel ratio. After the fuel is injected in the compression stroke, the fuel is injected in the expansion stroke, so that the combustion gas temperature rises due to the high number of combustions per unit time due to high rotation, and the excess oxygen causes the fuel to be injected in the expansion stroke. It is possible to effectively promote the warming-up of the catalyst 11 in a state in which the combustibility in the expansion stroke is increased while the discharge of unburned fuel is suppressed while preventing discharge.

The secondary air supply means 2 for supplying secondary air to the exhaust passage 3 to activate the exhaust gas purifying catalyst 11.
In the in-cylinder injection type engine provided with 0, when the temperature state determination means 16 determines that the exhaust gas purification catalyst 11 is in the low temperature state in the unwarmed state, the fuel is injected at least in the compression stroke, and the exhaust gas is exhausted. When it is determined that the purification catalyst 11 is in the high temperature state in the unwarmed state, early injection of fuel is performed between the intake stroke and the compression stroke so that the air-fuel ratio in the exhaust gas is leaner than 13. After performing the control, the fuel may be controlled to perform the latter-stage injection in the expansion stroke, and the secondary air may be supplied by the secondary air supply unit 20.

According to the above configuration, the exhaust gas purifying catalyst 11
Is determined to be in the low temperature state in the unwarmed state, the exhaust gas temperature is increased by the fuel injected in the compression stroke, thereby preventing the discharge of the unburned fuel and warming up the catalyst 11. When it is determined that the exhaust gas purifying catalyst 11 is in a high temperature state in the unwarmed state, the fuel injected in the expansion stroke is positively activated by the secondary air in the exhaust passage 3 and the like. Since the fuel can be burned, the warm-up of the catalyst 11 can be effectively promoted while preventing the emission of unburned fuel.

Further, in the above embodiment, when it is determined that the exhaust gas purifying catalyst 11 is in the high temperature state in the unwarmed state, the exhaust gas by the fuel injection before the ignition is compared with the case where the exhaust gas purification catalyst 11 is in the low temperature state. When the air-fuel ratio is controlled to be high, and it is determined that the exhaust gas purifying catalyst 11 is in a low temperature state in an unwarmed state, the ignition timing is controlled by the ignition timing control means 18 to a point higher than the MBT. When the exhaust gas purification catalyst is determined to be in the high temperature state in the unwarmed-up state, the ignition timing is retarded compared to when the exhaust gas purification catalyst 11 is in the low-temperature state in the unwarmed-up state. It is desirable to control so as to advance to the MBT side.

According to the above configuration, the exhaust gas purifying catalyst 11
Is in a low temperature state in a non-warmed state, the ignition timing is retarded by a predetermined amount from the MBT by the ignition timing control means 18 to raise the exhaust gas temperature and to warm up the catalyst 11. Can be effectively promoted.
Further, when the exhaust gas purification catalyst 11 has transitioned from a low temperature state to a high temperature state in an unwarmed state, the ignition timing is advanced to the MBT side as compared with the case where the exhaust gas purification catalyst 11 is in the low temperature state.
Since the engine torque can be secured without increasing the total fuel injection amount, deterioration of fuel efficiency can be prevented.

[0138] Further, a start judging means 19 for judging whether or not the engine is in a starting state based on the engine speed or the like.
A case where the engine state is determined to be in a starting state by the catalyst state determining means including the temperature state determining means 16 and the like for determining whether the exhaust gas purifying catalyst 11 is in an active state and the start determining means 19. In a first injection mode in which fuel is injected only during the intake stroke, when the catalyst is determined to be in a non-warmed state by the catalyst determination unit after the engine is started, the intake period is set to a predetermined time period. During the period from the stroke to the compression stroke, the fuel is dividedly injected, and a second injection mode is used in which the later injection timing is a compression stroke. After the predetermined time has elapsed, the fuel is divided into a compression stroke and an expansion stroke. Injection control means 1 for controlling the fuel injection timing so as to obtain a third injection mode in which the fuel is injected.
7 may be provided.

According to the above configuration, by injecting fuel only in the intake line at the start of the engine, the mixture can be made uniform and the startability of the engine can be ensured.
Immediately after the start of the engine, the fuel is split and injected within a period from the intake stroke to the compression stroke, whereby the temperature of the exhaust gas can be increased and the warm-up of the catalyst 11 can be promoted. Further, at a point in time when a predetermined time has elapsed after the start of the engine, a transition is made to a third injection mode in which fuel is divided into a compression stroke and an expansion stroke, and fuel injected in the expansion stroke is discharged into the exhaust passage 3. By burning the catalyst 11 and the like, it is possible to more effectively promote the warm-up of the catalyst 11 while preventing the discharge of unburned fuel.

Further, in the above embodiment, the fuel injection amount in the first injection mode to be injected before ignition is made larger than that in the second injection mode, and the fuel injection amount in the second injection mode is increased. It is desirable to control so as to increase the number of injections more than the third injection mode. According to the above configuration, when the engine is started, the air-fuel mixture is made relatively rich so that the startability of the engine can be ensured. It is possible to inject an amount of fuel that can promote warm-up. Further, when a predetermined time has elapsed after the start of the engine, the air-fuel mixture is made relatively lean, thereby preventing the fuel injected in the expansion stroke from being discharged in an unburned state, and Warm-up of the catalyst 11 can be further effectively promoted.

Further, in the above embodiment, the ignition timing in the second injection mode is retarded by a predetermined amount from the MBT by the ignition timing
The ignition timing in this injection mode may be controlled to be advanced to the MBT side as compared to the second injection mode. According to this configuration, immediately after the start of the engine, the ignition timing is retarded by a predetermined amount from the MBT,
By raising the temperature of the exhaust gas and effectively promoting the warm-up of the catalyst 11, the ignition timing is advanced to the MBT side when a predetermined time has elapsed after the start of the engine, as compared with immediately after the start of the engine. There is an advantage that a decrease in torque due to the air-fuel ratio being controlled to a lean state can be suppressed.

Further, in the above embodiment, when the temperature state determining means 16 determines that the exhaust gas purification catalyst 11 is in the low temperature state in the unwarmed state, the fuel is injected at least in the compression stroke. Although the example has been described, when it is determined that the exhaust gas purification catalyst 11 is in the low temperature state in the unwarmed state, the fuel injection control unit 17 performs the fuel injection from the intake stroke to the ignition timing. When the exhaust gas purifying catalyst 11 is determined to be in a high temperature state in the unwarmed state, the amount of fuel injected between the intake stroke and the ignition timing is determined. May be set to be leaner than the stoichiometric air-fuel ratio, and the fuel may be injected during the expansion stroke after ignition.

According to the above configuration, the exhaust gas purifying catalyst 11
Is determined to be in the low temperature state of the warm-up state,
While performing fuel injection from the intake stroke to the ignition timing,
By executing the temperature increase control for increasing the temperature of the exhaust gas purification catalyst 11, the warm-up of the exhaust gas purification catalyst 11 can be effectively promoted. Further, when it is determined that the exhaust gas purification catalyst 11 is in a high temperature state without being warmed up, the amount of fuel injected between the intake stroke and the ignition timing becomes leaner than the stoichiometric air-fuel ratio. By setting as above, the fuel injected in the expansion stroke after ignition is burned in the combustion chamber or the exhaust passage in a state where the excess oxygen is sufficiently secured, thereby suppressing the emission of unburned fuel. Thus, the warm-up of the exhaust gas purifying catalyst 11 can be effectively promoted.

In particular, in the above embodiment, when it is determined that the exhaust gas purifying catalyst 11 is in a high temperature state in which the exhaust gas purifying catalyst 11 is not warmed up, the ignition timing control means 18 sets the ignition timing to the MBT.
If it is configured to retard by a predetermined amount than
Since the exhaust gas temperature can be increased by slowing down the combustion, the warm-up of the exhaust gas purifying catalyst 11
It can be more effectively promoted.

Further, when the fuel injection is performed at least in the intake stroke at the time of executing the control for retarding the ignition timing by a predetermined amount from the MBT, the fuel injected in the intake stroke enters the cylinder by the fuel. Since a uniform air-fuel mixture can be formed to improve the combustibility, the ignition timing can be retarded. Therefore, the ignition timing is retarded by a predetermined amount from the MBT by the ignition timing control means 18 so that the exhaust gas temperature is raised and the warm-up of the exhaust gas purification catalyst 11 is maintained while maintaining good combustion. There is an advantage that it can be effectively promoted.

When it is determined that the exhaust gas purifying catalyst 11 is in the high temperature state in the unwarmed state, the air-fuel ratio in the exhaust gas is controlled by variably controlling the fuel injection amount injected in the expansion stroke. , The state may be repeatedly changed between the rich state and the lean state. With this configuration, the amount of fuel injected during the expansion stroke is variably controlled to repeatedly change the air-fuel ratio in the exhaust gas between the rich state and the lean state, thereby storing the catalyst in the lean state. The warm-up of the exhaust gas purification catalyst 11 can be effectively promoted while preventing the emission of unburned fuel by appropriately reacting the supplied oxygen with the surplus fuel supplied in a rich state.

For example, between the cylinders of an engine having a plurality of cylinders, the fuel injection amount in the expansion stroke is variably controlled, or as shown in FIG. By performing the fuel injection in the expansion stroke intermittently by alternately providing the cylinders for performing the fuel injection only in the compression stroke and the like without performing the injection, the air-fuel ratio in the exhaust gas is set to the rich state and the lean state. When it is configured to change repeatedly, the warm-up of the exhaust gas purification catalyst 11 can be effectively promoted while preventing the discharge of unburned fuel.

Also, by controlling the amount of fuel injection during the expansion stroke variably in the same cylinder of an engine having a plurality of cylinders, or by intermittently executing the fuel injection during the expansion stroke within the same cylinder, the exhaust gas The same effect can be obtained even when the medium air-fuel ratio is repeatedly changed between the rich state and the lean state.

When it is determined that the exhaust gas purifying catalyst 11 is in the high temperature state in the unwarmed state, the air-fuel ratio in the exhaust gas is controlled to be in the range of 14 to 17. In this case, by setting the air-fuel ratio to 14 or more, it is possible to prevent the air-fuel ratio from becoming unnecessarily rich and deteriorating fuel efficiency, and by setting the air-fuel ratio to 17 or less, the air-fuel ratio becomes necessary. As described above, there is an advantage that it is possible to prevent the exhaust gas from becoming lean and being cooled.

When the exhaust gas purification catalyst 11 is determined to be in a low temperature state in the unwarmed state, a specific example of the temperature rise control for increasing the exhaust gas temperature is as follows. In some cases, when it is determined that the engine is in a low temperature state, the ignition timing is retarded by a predetermined amount from the MBT, thereby executing a temperature increase control for increasing the exhaust gas temperature. That is, the exhaust gas purification catalyst 1
When the engine 1 is in the low temperature state in the unwarmed state, the ignition timing is retarded by a predetermined amount from the MBT to slow down the combustion, so that the exhaust gas temperature is raised early and the exhaust gas purification catalyst 11 Warm-up can be effectively promoted.

When it is determined that the exhaust gas purifying catalyst 11 is in a low temperature state in the unwarmed state, fuel is injected at least in the compression stroke, and the fuel injection timing is the same as that in the warm stratification operation. You may comprise so that it may advance more than at the time of warm stratification operation. With such a configuration, a relatively rich air-fuel mixture can be formed around the ignition plug by the fuel injected in the compression stroke, and the fuel injection timing is set to the same or advanced state as in the warm stratification operation. Thereby, it is possible to prevent the formation of an unnecessarily rich air-fuel mixture around the ignition plug, appropriately promote the vaporization and atomization of the fuel, and thereby maintain the good ignitability. At the same time, it is possible to effectively warm up the exhaust gas purifying catalyst 11 by promoting the rise of the exhaust gas temperature.

If it is determined that the exhaust gas purifying catalyst 11 is in a low temperature state in the unwarmed state, fuel is injected at least in the compression stroke, and this compression stroke injection is performed at 3/4 of the compression stroke. Is terminated before the lapse of time, the formation of an unnecessarily rich air-fuel mixture around the ignition plug 4 is prevented, and the vaporization and atomization of the fuel are appropriately promoted. be able to.

In the above-described embodiment, a valve-opening overlap amount varying means for varying the overlap amount between the intake valve and the exhaust valve is provided, and it is determined that the exhaust gas purification catalyst 11 is in the low temperature state in the unwarmed state. In such a case, the valve opening overlap amount may be reduced. According to this configuration, when the exhaust gas purifying catalyst 11 is in a low temperature state in an unwarmed state, the amount of overlap between the intake valve and the exhaust valve is set small, and the internal EGR amount is reduced. The exhaust gas temperature can be effectively increased. Further, when the exhaust gas purifying catalyst 11 is in a high temperature state in an unwarmed state, the amount of overlap between the intake valve and the exhaust valve is set to be large and the internal EGR amount is increased, so that the combustion efficiency is improved. Therefore, the emission of unburned fuel can be more effectively suppressed.

When the exhaust gas purifying catalyst 11 is in a high temperature state in an unwarmed state, it is desirable that the air-fuel ratio in the exhaust gas is adjusted to be in the range of 14 to 17. With such a configuration, the air-fuel ratio becomes unnecessarily rich to prevent a decrease in exhaust gas temperature due to latent heat of vaporization of the fuel or a deterioration in combustion due to a shortage of oxygen, and a deterioration in fuel efficiency and an increase in unburned fuel in the exhaust passage. Can be prevented from being exhausted. Also, without causing the situation that the air-fuel ratio becomes leaner than necessary and the combustibility deteriorates,
In addition, it is possible to appropriately execute the temperature increase control for increasing the temperature of the exhaust gas purification catalyst 11 while suppressing the decrease in the exhaust gas temperature.

Further, O ₂ for detecting the air-fuel ratio in the exhaust gas is used.
By providing a sensor 10 and performing feedback control of the fuel injection amount based on the output value of the O ₂ sensor 10,
When the air-fuel ratio in the exhaust gas is configured to be in the range of 14 to 17, the control is performed based on the output value of the O ₂ sensor 10 so that the air-fuel ratio in the exhaust gas is in the range of 14 to 17. Can be properly executed with high accuracy.

Further, in the above embodiment, the case where the warm-up of the exhaust gas purifying catalyst 11 is promoted when the exhaust gas purifying catalyst 11 is not warmed up is explained. When the temperature state determining means 16 determines that the exhaust gas purifying catalyst 11 has become inactive due to the temperature decrease of the exhaust gas purifying catalyst 11,
The amount of fuel injected between the intake stroke and the ignition timing is set so that the in-cylinder air-fuel ratio is leaner than the stoichiometric air-fuel ratio, and the fuel is controlled to be injected during the expansion stroke after ignition. You may comprise.

According to the above configuration, the stratified-lean operation is continued for a predetermined time, and the like.
By setting the amount of fuel injected between the intake stroke and the ignition timing to be leaner than the stoichiometric air-fuel ratio when the temperature is lowered and becomes inactive,
The fuel injected in the expansion stroke after ignition is burned in the combustion chamber or in the exhaust passage 3 in a state where the excess oxygen is sufficiently secured, thereby suppressing the discharge of the unburned fuel and allowing the catalyst 11 to be quickly discharged. Can be reactivated.

When it is determined that the exhaust gas purifying catalyst 11 has become inactive, the amount of fuel injected during the expansion stroke is variably controlled to reduce the air-fuel ratio in the exhaust gas to the rich state. And a lean state may be repeatedly changed. According to this configuration, when the exhaust gas purification catalyst 11 becomes inactive due to a decrease in the temperature of the exhaust gas purification catalyst 11 during the stratified operation, the fuel injection amount injected in the expansion stroke can be varied. By controlling and repeatedly changing the air-fuel ratio in the exhaust gas between the rich state and the lean state, the catalyst 11
Can properly react the oxygen stored in the exhaust gas with the excess fuel supplied in a rich state, so that the emission of unburned fuel can be prevented and the reactivation of the exhaust gas purification catalyst 11 is effectively promoted. There is an advantage that you can.

Further, when it is determined that the exhaust gas purifying catalyst 11 has become inactive, the air-fuel ratio in the exhaust gas is controlled so as to be in the range of 14 to 17. During the stratified lean operation, the exhaust gas purifying catalyst 11
Becomes inactive, the air-fuel ratio becomes unnecessarily rich and the exhaust gas temperature drops due to latent heat of vaporization of the fuel,
In addition, deterioration of combustion due to lack of oxygen is prevented, and deterioration of fuel efficiency and discharge of unburned fuel to the exhaust passage 3 can be prevented. Further, the exhaust gas purifying catalyst 1 does not cause a situation in which the air-fuel ratio becomes leaner than necessary and the combustibility deteriorates, and the exhaust gas purification catalyst 1
The control for raising the temperature and reactivating the temperature can be appropriately performed.

Further, in the above-described embodiment, the O ₂ sensor 10 for detecting the air-fuel ratio in the exhaust gas is provided, and the fuel injection amount is feedback-controlled based on the output value of the O ₂ sensor 10, whereby the exhaust gas Air-fuel ratio of 14-17
May be configured to be within the range. According to this configuration, when the exhaust gas purifying catalyst 11 becomes inactive due to a decrease in the temperature of the exhaust gas purifying catalyst 11 during the stratified lean operation, based on the output value of the O ₂ sensor 10, The control for setting the air-fuel ratio in the exhaust gas within the range of 14 to 17 can be appropriately performed with high accuracy.

Further, in the control apparatus for a direct injection type engine provided with the exhaust gas purifying catalyst 11 provided in the exhaust passage 3 and the fuel injection valve 5 for directly injecting fuel into the combustion chamber, the exhaust gas purifying catalyst A temperature state determination means 16 for determining the temperature state of the exhaust gas purification catalyst 11; and a determination from the temperature state determination means 16 that the exhaust gas purifying catalyst 11 is not warmed up. The fuel injection is divided into a post-ignition expansion stroke and the fuel injection is performed. When the exhaust gas purification catalyst 11 is not warmed up at a high temperature, the fuel is controlled so as to increase the fuel injection amount in the expansion stroke as compared with a low temperature. The structure provided with the injection control means 17 may be adopted.

According to the above configuration, the exhaust gas purifying catalyst 11
If it is determined that the engine is not yet warmed up, the fuel injection is performed in a divided manner between the intake stroke and the ignition timing and the expansion stroke after ignition, and the fuel injected in the expansion stroke is injected into the combustion chamber. In addition, by burning in the exhaust passage 3, the temperature of the exhaust gas purification catalyst 11 can be increased. When the exhaust gas purifying catalyst 11 is in a low temperature in an unwarmed state,
By setting the amount of fuel injected during the expansion stroke after ignition small, it is possible to suppress the emission of unburned fuel,
When the exhaust gas purifying catalyst 11 is in a high temperature in an unwarmed state, a large amount of fuel is injected in an expansion stroke after ignition, so that a large amount of fuel is burned in the combustion chamber or in the exhaust passage 3. Warm-up of the catalyst 11 can be further effectively promoted.

[0163]

As described above, the present invention provides a temperature state determining means for determining the temperature state of an exhaust gas purifying catalyst,
When the temperature state determination means determines that the exhaust gas purifying catalyst is in a low temperature state in an unwarmed state,
Injecting fuel at least in the compression stroke, and when it is determined that the exhaust gas purification catalyst is in a high temperature state in an unwarmed state, the amount of fuel injected between the intake stroke and the compression stroke is reduced in the exhaust gas. Since the air-fuel ratio is set to be leaner than the stoichiometric air-fuel ratio, and the fuel injection control means for controlling the fuel injection during the expansion stroke is provided, the exhaust gas purifying catalyst may be in a low temperature state in an unwarmed state. When it is determined that there is, by raising the exhaust gas temperature by the fuel injected in the compression stroke, it is possible to promote the warm-up of the catalyst while preventing the discharge of unburned fuel, and the exhaust gas purification catalyst When it is determined that the engine is in a high temperature state in an unwarmed state, in a state where the excess oxygen is sufficiently secured by setting the air-fuel ratio in the exhaust gas to be leaner than the stoichiometric air-fuel ratio, By burning the fuel injected in Zhang stroke in the exhaust passage, etc., while preventing the discharge of unburned fuel, there is an advantage that warming-up of the catalyst can be more effectively promoted.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a control device for a direct injection engine according to the present invention.

FIG. 2 is a graph showing an operation range in a cold state.

FIG. 3 is a graph showing an operation range in a warm state.

FIG. 4 is a flowchart showing a control operation by the control device.

FIG. 5 is a time chart showing a control state of the direct injection engine.

FIG. 6 is a time chart showing a control state of fuel injection.

[Explanation of symbols]

Reference Signs List 3 exhaust passage 5 fuel injection valve 10 O ₂ sensor 11 exhaust gas purification catalyst 16 temperature state determination means 17 fuel injection control means 18 ignition timing control means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 41/02 325 F02D 41/02 325A 41/04 305 41/04 305Z 41/14 310 41/14 310E 41 / 34 41/34 F H L 45/00 312 45/00 312R F02P 5/15 F02P 5/15 E

Claims (42)

[Claims] An in-cylinder injection engine control device comprising: an exhaust gas purifying catalyst provided in an exhaust passage; and a fuel injection valve for directly injecting fuel into a combustion chamber. Temperature state determining means for determining
When the temperature state determination means determines that the exhaust gas purifying catalyst is in a low temperature state in an unwarmed state,
If the fuel is injected at least in the compression stroke, and it is determined that the exhaust gas purification catalyst is in the high temperature state in the unwarmed state, the amount of fuel injected between the intake stroke and the compression stroke is reduced by the amount of air in the exhaust gas. A fuel injection control means for setting a fuel ratio to be leaner than a stoichiometric air-fuel ratio and controlling fuel injection to be performed during an expansion stroke. 2. An air-fuel ratio in exhaust gas is controlled to be leaner than 13 when it is determined that the exhaust gas purifying catalyst is not yet warmed up. Control device for in-cylinder injection type engine. 3. When the exhaust gas purifying catalyst is determined to be in a low temperature state in an unwarmed state, control is performed such that the air-fuel ratio in the exhaust gas falls within a range of 13 to 16. The control device for a direct injection engine according to claim 1. 4. When the exhaust gas purifying catalyst is determined to be in a high temperature state in an unwarmed state, control is performed such that the air-fuel ratio in the exhaust gas falls within a range of 13 to 16. The control device for a direct injection engine according to claim 3. 5. A control apparatus for a cylinder injection engine according to claim 3, further comprising an O ₂ sensor for detecting the air-fuel ratio in the exhaust gas, after activation of the O ₂ sensor, the output of the O ₂ sensor 2. The control device for a direct injection engine according to claim 1, wherein the fuel injection amount is feedback-controlled based on the value so that the air-fuel ratio in the exhaust gas becomes a stoichiometric air-fuel ratio. 6. The fuel injection system according to claim 1, wherein when it is determined that the exhaust gas purification catalyst is in a low temperature state in an unwarmed state, fuel is divided into an intake stroke and a compression stroke and fuel is injected. A control device for a direct injection engine according to claim 3. 7. When the exhaust gas purifying catalyst is determined to be in a low temperature state in an unwarmed state, the first stage of the compression stroke;
The control device for a direct injection engine according to any one of claims 1 to 3, wherein the fuel is injected separately during a later stage of the compression stroke. 8. The fuel injection system according to claim 1, wherein when it is determined that the exhaust gas purifying catalyst is in a low temperature state in an unwarmed state, the fuel is collectively injected in a compression stroke.
A control device for a direct injection engine according to claim 5. 9. The fuel injection system according to claim 1, wherein when it is determined that the exhaust gas purifying catalyst is in a high temperature state in an unwarmed state, fuel is divided into a compression stroke and an expansion stroke and fuel is injected. The control device for a direct injection engine according to claim 2. 10. The fuel injection system according to claim 1, wherein when it is determined that the exhaust gas purifying catalyst is in a high temperature state in an unwarmed state, fuel is divided into an intake stroke and an expansion stroke and fuel is injected. The control device for a direct injection engine according to claim 2. 11. When the exhaust gas purifying catalyst is determined to be in a high temperature state in an unwarmed state, fuel is divided into an intake stroke, a compression stroke, and an expansion stroke and fuel is injected. The control device for a direct injection engine according to claim 1 or 2. 12. When it is determined that the exhaust gas purifying catalyst is in a high temperature state in an unwarmed state, the fuel injection is performed in an expansion stroke in addition to fuel injection in a low temperature state in the unwarmed state. The control device for a direct injection engine according to any one of claims 6 to 8, wherein the additional injection is performed. 13. When the exhaust gas purifying catalyst is determined to be in a high temperature state in an unwarmed state, the fuel is injected in an expansion stroke in addition to fuel injection in a low temperature state in the unwarmed state. 9. The fuel injection device according to claim 8, wherein the additional fuel injection is performed and the fuel amount of the additional fuel injection is controlled to be equal to or less than the fuel injected before the ignition.
A control device for an in-cylinder injection engine according to the above description. 14. When it is determined that the exhaust gas purifying catalyst is in a high temperature state in an unwarmed state, in addition to fuel injection in a low temperature state in the unwarmed state, a fuel is added in an expansion stroke. 8. The in-cylinder injection engine according to claim 6, wherein the additional injection is performed, and the fuel amount of the additional injection is controlled to be smaller than the fuel amount injected before ignition. Control device. 15. A control apparatus for an in-cylinder injection type engine having an exhaust gas purifying catalyst provided in an exhaust passage and a fuel injection valve for directly injecting fuel into a combustion chamber. When the temperature state determining means determines that the exhaust gas catalyst is in the unwarmed state, in the operating region where the engine load is equal to or less than a predetermined load, the fuel is discharged between the intake stroke and the compression stroke. And a fuel injection control means for controlling to inject fuel in a compression stroke and an expansion stroke in an operation region on a higher load side than the operation region. A control device for a direct injection engine. 16. The fuel injection amount in the compression stroke is set such that the air-fuel ratio in the exhaust gas is leaner than the stoichiometric air-fuel ratio in the high load operation region. Control device for in-cylinder injection type engine. 17. The fuel injection system according to claim 15, wherein in the high-load operation region, fuel is divided into a first half of a compression stroke, a second half of a compression stroke, and an expansion stroke.
A control device for a direct injection engine according to claim 16. 18. A control system for an in-cylinder injection type engine having an exhaust gas purifying catalyst provided in an exhaust passage and a fuel injection valve for directly injecting fuel into a combustion chamber. When the temperature state determining means determines that the exhaust gas purification catalyst is not warmed up, the fuel is divided into an intake stroke and a compression stroke in a low engine speed region. In the operating region on the higher rotation side than the low rotation region of the engine, the fuel is divided into an injection stroke and a compression stroke, and the fuel is divided into an expansion stroke, and the fuel is injected from the intake stroke to the compression stroke. A fuel injection control means for performing injection control such that an amount of injected fuel between the exhaust gas and the air-fuel ratio in the exhaust gas is leaner than a stoichiometric air-fuel ratio. 19. A temperature control device for an in-cylinder injection engine, comprising: an exhaust gas purifying catalyst provided in an exhaust passage; and a fuel injection valve for directly injecting fuel into a combustion chamber. When the temperature state determining means determines that the exhaust gas purifying catalyst is in the low temperature state in the unwarmed state, the fuel is injected at least in the compression stroke, and the exhaust gas purifying catalyst When it is determined that the engine is in the high temperature state in the unwarmed state, the fuel is divided into a period from the intake stroke to the compression stroke and a period under the condition that the air-fuel ratio in the exhaust gas is leaner than 13. A fuel injection control means for controlling the fuel injection and supplying secondary air for activating the exhaust gas purification catalyst when it is determined that the catalyst is in a high temperature state in an unwarmed state. A control device for a direct injection type engine, comprising: 20. When it is determined that the catalyst is in the high temperature state in the unwarmed state, the air-fuel ratio in the exhaust gas by the fuel injection before ignition is higher than in the low temperature state. Control, and when it is determined that the exhaust gas purifying catalyst is in a low temperature state in an unwarmed state, the ignition timing control means retards the ignition timing by a predetermined amount from the MBT, and the exhaust gas purifying catalyst 20. The in-cylinder injection according to claim 19, wherein when it is determined that the engine is in the high temperature state in the unwarmed state, the ignition timing is controlled to be advanced to the MBT side as compared with the low temperature state. Control device for the expression engine. 21. A control device for a direct injection type engine including an exhaust gas purifying catalyst provided in an exhaust passage and a fuel injection valve for directly injecting fuel into a combustion chamber, whether or not the engine is in a starting state. Starting state determining means for determining whether the exhaust gas purifying catalyst is in an active state; and a starting state determining means for determining whether the engine is in a starting state. The first injection mode in which fuel is injected only during the stroke, and when the catalyst determination unit determines that the catalyst is not warmed up after the engine is started, the predetermined period set in advance is:
In a second injection mode in which fuel is dividedly injected during a period from an intake stroke to a compression stroke, and a later injection timing is set to a compression stroke, and after the above-described predetermined time has elapsed, the fuel is divided into a compression stroke and an expansion stroke. A fuel injection control means for controlling a fuel injection timing so as to obtain a third injection mode for injecting fuel. 22. The fuel injection amount in the first injection mode, which is injected before ignition, is made larger than that in the second injection mode, and the fuel injection amount in the second injection mode is increased in the third injection mode. 22. The control device for a direct injection engine according to claim 21, wherein the control is performed so as to increase the number. 23. An ignition timing in the second injection mode,
Ignition timing control means for controlling the ignition timing in the third injection mode to be advanced toward the MBT side as compared to the second injection mode, while retarding the ignition timing by a predetermined amount from the MBT. 23. The control device for a direct injection engine according to claim 21, wherein 24. A control system for an in-cylinder injection type engine having an exhaust gas purifying catalyst provided in an exhaust passage and a fuel injection valve for directly injecting fuel into a combustion chamber. If the temperature state determining means determines that the exhaust gas purification catalyst is in a low temperature state in the unwarmed state, fuel injection is performed from the intake stroke to the ignition timing. When the exhaust gas purifying catalyst is determined to be in a high temperature state in the unwarmed state, the amount of fuel injected between the intake stroke and the ignition timing is determined. Fuel injection control means for setting a leaner state than the stoichiometric air-fuel ratio and controlling fuel injection during an expansion stroke after ignition. Control device. 25. When it is determined that the exhaust gas purifying catalyst is in a high temperature state in an unwarmed state, the ignition timing is set to M
25. The control device for a direct injection engine according to claim 24, further comprising an ignition timing control means for controlling the ignition timing to be retarded by a predetermined amount from the BT. 26. The fuel injection system according to claim 25, wherein when performing the control for retarding the ignition timing by a predetermined amount from the MBT, the fuel injection is controlled at least in the intake stroke.
A control device for an in-cylinder injection engine according to the above description. 27. When it is determined that the exhaust gas purifying catalyst is in a high temperature state in an unwarmed state, the air-fuel ratio in the exhaust gas is controlled by variably controlling a fuel injection amount injected in an expansion stroke. 25. The apparatus according to claim 24, wherein the state is repeatedly changed between a rich state and a lean state.
A control device for an in-cylinder injection engine according to the above description. 28. An air-fuel ratio in exhaust gas is repeatedly changed between a rich state and a lean state by variably controlling a fuel injection amount in an expansion stroke between respective cylinders of an engine having a plurality of cylinders. The control device for a direct injection engine according to claim 27, wherein the control device is configured. 29. An air-fuel ratio in exhaust gas is repeatedly changed between a rich state and a lean state by variably controlling a fuel injection amount in an expansion stroke in the same cylinder of an engine having a plurality of cylinders. The control device for a direct injection engine according to claim 27, wherein the control device is configured. 30. The fuel injection system according to claim 28, wherein the fuel injection in the expansion stroke is intermittently performed so that the air-fuel ratio in the exhaust gas is repeatedly changed between a rich state and a lean state. 30. The control device for a direct injection engine according to claim 29. 31. When the exhaust gas purifying catalyst is determined to be in a high temperature state in an unwarmed state, control is performed so that the air-fuel ratio in the exhaust gas falls within a range of 14 to 17. A control device for a direct injection engine according to claim 24. 32. When it is determined that the exhaust gas purifying catalyst is in a low temperature state in an unwarmed state, the ignition timing is set to M
25. The control device for a direct injection engine according to claim 24, further comprising an ignition timing control means for executing a temperature increase control for increasing an exhaust gas temperature by retarding the exhaust gas by a predetermined amount from the BT. 33. When it is determined that the exhaust gas purifying catalyst is in the low temperature state in the unwarmed state, fuel is injected at least in the compression stroke, and the fuel injection timing is the same as that in the warm stratification operation. 25. The control device for a direct injection type engine according to claim 24, wherein the angle is advanced more than during the warm stratification operation. 34. When it is determined that the exhaust gas purifying catalyst is in a low temperature state in an unwarmed state, fuel is injected at least in a compression stroke, and the compression stroke injection is performed in 3/4 of the compression stroke. 25. The control apparatus for a direct injection engine according to claim 24, wherein the control is finished before the lapse of time. 35. An apparatus according to claim 35, further comprising a valve-opening overlap varying means for varying an amount of overlap between the intake valve and the exhaust valve, wherein when it is determined that the exhaust gas purifying catalyst is in a low temperature state in an unwarmed state, 25. The control apparatus for a direct injection engine according to claim 24, wherein the valve opening overlap amount is reduced. 36. When it is determined that the exhaust gas purifying catalyst is in a low temperature state in an unwarmed state, the exhaust gas temperature is raised by adjusting the air-fuel ratio in the exhaust gas within a range of 14 to 17. 25. The control device for a direct injection engine according to claim 24, wherein the control device is configured to execute a temperature rise control. 37. An O ₂ sensor for detecting the air-fuel ratio in the exhaust gas, and the air-fuel ratio in the exhaust gas is adjusted to 14 to 17 by feedback-controlling the fuel injection amount based on the output value of the O ₂ sensor. 37. The control device for a direct injection type engine according to claim 31, wherein the control device is configured to fall within the range. 38. A control device for a direct injection type engine having an exhaust gas purifying catalyst provided in an exhaust passage and a fuel injection valve for directly injecting fuel into a combustion chamber, wherein a temperature state of the exhaust gas purifying catalyst is provided. When the temperature state determination means determines that the exhaust gas purification catalyst has become inactive due to a decrease in temperature of the exhaust gas purification catalyst during the stratified lean operation,
Fuel injection that sets the amount of fuel injected between the intake stroke and the ignition timing so that the in-cylinder air-fuel ratio is leaner than the stoichiometric air-fuel ratio, and controls fuel injection during the expansion stroke after ignition A control device for a direct injection type engine, comprising: a control unit. 39. When it is determined that the exhaust gas purifying catalyst has become inactive, the air-fuel ratio in the exhaust gas is changed to the rich state by variably controlling the amount of fuel injected during the expansion stroke. 39. The control device for a direct injection engine according to claim 38, wherein the control device is configured to repeatedly change to a lean state. 40. When it is determined that the exhaust gas purifying catalyst has become inactive, the air-fuel ratio in the exhaust gas is set to 14 to 1
39. The control device for a direct injection engine according to claim 38, wherein the control is performed so as to fall within a range of 7. 41. An air-fuel ratio in the exhaust gas of 14 to 17 is provided by providing an O ₂ sensor for detecting an air-fuel ratio in the exhaust gas and performing feedback control of the fuel injection amount based on an output value of the O ₂ sensor. 39. The control device for a direct injection engine according to claim 38, wherein the control device is configured to fall within the range of: 42. A control apparatus for an in-cylinder injection engine including an exhaust gas purifying catalyst provided in an exhaust passage and a fuel injection valve for directly injecting fuel into a combustion chamber, wherein a temperature state of the exhaust gas purifying catalyst is provided. If the temperature state determining means determines that the exhaust gas purifying catalyst is not in a warm-up state, the temperature state determining means determines whether the exhaust gas purification catalyst is in an unwarmed state, between the intake stroke and the ignition timing, and the expansion stroke after ignition. And fuel injection control means for controlling the amount of fuel injection during the expansion stroke to be larger when the exhaust gas purifying catalyst is in a high temperature in an unwarmed state than in a low temperature. A control device for a direct injection engine, comprising: