JPH06117292A - Direct injection type engine - Google Patents

Abstract

PURPOSE:To provide a direct injection type engine by which an exhaust gas temperature can be raised speedily when an engine is cooled and a temperature of exhaust gas purifying catalyst can be raised speedily to an activation temperature or above. CONSTITUTION:In a diesel engine DE, when the number of revolutions of the engine is low and/or a rack position (engine load) is small, an air intake throttle valve 18 is throttled according to the number of revolutions of the engine and the rack position, and stratified combustion is accelerated, and an EGR quantity is increased according to the number of revolutions of the engine and the rack position, and combustion speed is increased, and combustibility is heightened thereby. When the engine is cooled, the EGR quantity and a throttling quantity of the air intake throttle valve 18 are increased more than when the engine is warmed, and an exhaust gas temperature is raised, and a temperature of exhaust gas purifying catalyst in a catalyst converter 10 is raised speedily up to an activation temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct injection engine.

[0002]

2. Description of the Related Art Basically, air is supplied to a combustion chamber without throttling without providing a throttle valve in an intake system, while fuel is directly supplied into a cylinder to control an engine output by a fuel supply amount. Such a so-called direct injection engine has been conventionally known (for example, JP-A-62-1655).
No. 37). In such a direct injection type engine, for example, a direct injection type diesel engine, after the cylinder is filled with air, fuel is injected into the air to perform stratified combustion.

[0003]

However, in such a direct injection engine, when the fuel is not fully injected, that is, when the load is partial, the air becomes excessive with respect to the fuel in the cylinder. Will increase. For this reason, in a direct injection engine, the exhaust gas temperature decreases due to excess air during partial load, especially under low load.

By the way, generally, in the exhaust system of an engine,
An exhaust gas purifying catalyst (catalytic converter) is provided for oxidizing HC (hydrocarbon), CO (carbon monoxide), etc. generated in the exhaust gas by unburned fuel or incomplete combustion of the fuel. Further, such an exhaust gas purifying catalyst normally does not sufficiently exhibit the exhaust gas purifying action unless the activation temperature becomes higher than the activation temperature. Therefore, when the engine is cooled after the engine is started, the exhaust gas purification rate becomes low until the exhaust gas purification catalyst is heated to a temperature equal to or higher than the activation temperature by the exhaust gas, resulting in a problem that emission is deteriorated.

Further, in general, when the engine is cold, the combustibility is lower than in the normal state and the amount of unburned fuel discharged together with the exhaust gas is increased, so that the emission becomes worse. Therefore, when the engine is cold, it is necessary to quickly raise the temperature of the exhaust gas purification catalyst in order to improve the emission performance, but in the direct injection type engine, as described above, the exhaust gas is exhausted during partial load (that is, during normal operation). Since the gas temperature becomes low, it takes a long time for the exhaust gas purifying catalyst to reach the activation temperature after the engine is started, and there is a problem that the emission deteriorates.

The present invention has been made in order to solve the above-mentioned conventional problems, and it is possible to quickly raise the temperature of exhaust gas when the engine is cold, and to quickly raise the temperature of the exhaust gas purifying catalyst to above the activation temperature. An object of the present invention is to provide a direct injection type engine that can raise the temperature.

[0007]

To achieve the above object, as shown in FIG. 1, the first invention is a direct injection type in which a fuel supply means B for directly supplying fuel to a combustion chamber A is provided. In the engine, an intake throttle valve C capable of restricting the intake air amount and the intake throttle valve C depending on the operating state of the engine
Intake control means D for controlling the intake throttle amount, cold engine state detecting means E for detecting the cold state of the engine, and cold engine state detecting means E for detecting that the engine is in the cold state, as compared with the normal time. A direct-injection engine is provided, which is provided with an intake correction control means F for correcting and controlling the intake throttle valve C so that the intake throttle amount becomes large.

A second aspect of the invention is a direct injection engine provided with a fuel supply means B for directly supplying fuel to a combustion chamber A, an intake throttle valve C capable of restricting an intake amount, and an operating state of the engine. Is in a predetermined intake throttle region, the intake control means D for controlling the intake throttle valve C so as to throttle the intake amount, the cold state detecting means E for detecting the cold state of the engine, and the cold state detecting means E are used. A direct-injection engine is provided, which is provided with an intake air correction control unit F that corrects the intake throttle region in an expansion direction when it is detected that the engine is in a cold state.

In a third aspect of the present invention, in a direct injection engine provided with a fuel supply means B for directly supplying fuel to a combustion chamber A, an intake throttle valve C capable of restricting an intake amount and an operating state of the engine. Is in a predetermined intake throttle region, intake control means D for controlling the intake throttle amount of the intake throttle valve C in accordance with the operating state, cold state detection means E for detecting the cold state of the engine, and cold state detection thereof. When it is detected by the means E that the engine is in a cold state, the intake throttle region is corrected in the expansion direction, and the intake throttle valve C is corrected so that the intake throttle amount is larger than in the normal state. A means (F) is provided to provide a direct injection engine.

A fourth aspect of the present invention is an exhaust gas recirculation system capable of recirculating a part of exhaust gas to an intake system in a direct injection engine provided with a fuel supply means B for directly supplying fuel to a combustion chamber A. Means G, intake control means D for controlling the exhaust gas recirculation amount of the exhaust gas recirculation means G according to the operating state of the engine, cold state detection means E for detecting the cold state of the engine, and cold state detection means When it is detected by E that the engine is in the cold state, an intake air correction control means F for correcting and controlling the exhaust gas recirculation means G is provided so that the exhaust gas recirculation amount becomes larger than in the normal state. The featured direct injection engine is provided.

In a fifth aspect of the present invention, in the direct injection engine according to any one of the first to fourth aspects, the intake control means D and the intake correction control means F control the controlled object by feedback control. To provide a direct-injection engine.

In a sixth aspect of the present invention, in the direct injection engine according to the fifth aspect of the present invention, the intake control means D and the intake correction control means F perform proportional operation proportional to the deviation and differential operation proportional to the change rate of the deviation. Provided is a direct injection engine characterized by performing feedback control based on the above. The direct injection engine in the first to sixth aspects of the invention includes an engine in which fuel is directly supplied to the pre-combustion chamber,
Of course, for example, an indirect injection type diesel engine is also included.

[0013]

EXAMPLES Examples of the present invention will be specifically described below.
As shown in FIG. 2, in the direct injection diesel engine DE, which is one of the direct injection engines, when the intake valve 1 is opened, air is sucked into the combustion chamber 3 from the intake port 2 (intake stroke ), The air is compressed by the piston 4 (compression stroke), fuel (for example, methanol, light oil, etc.) is injected from the fuel injection valve 5 into the compressed and heated air, and this fuel is heated to a high temperature. And the glow plug 6 are used to ignite and burn (combustion stroke). Then, the combustion gas (exhaust gas) in the combustion chamber 3 is discharged to the exhaust passage 9 through the exhaust port 8 when the exhaust valve 7 is opened (exhaust stroke). In the exhaust passage 9, a catalytic converter 10 provided with an exhaust gas purifying catalyst for purifying unburned fuel, HC, CO, etc. in the exhaust gas.
Is installed. The fuel injection valve 5 corresponds to "fuel supply means" described in the claims.

The four strokes of intake, compression, combustion, and exhaust are repeated, and the piston 4 reciprocates in the cylinder axis direction, and this reciprocal movement is connected to the connecting rod 1.
It is adapted to be converted into a rotary motion by 1 and a crank pin 12 and transmitted to a crank shaft (not shown).
A recess 14 is formed on the top surface of the piston 4 for allowing the combustion chamber 3 to have a predetermined shape and volume when the piston 4 is at the top dead center position.

In order to supply air to the combustion chamber 3, the upstream end
A common intake passage 15 (not shown) that is open to the atmosphere is provided, and the downstream end of the common intake passage 15 is connected to a surge tank 16 that stabilizes the flow of air. The surge tank 16 is further connected to the upstream end of the branch intake passage 17, and the downstream end of the branch intake passage 17 is connected to the intake port 2.

Then, in the common intake passage 15, as will be described later, the air supplied to the combustion chamber 3 is supplied to the engine DE.
An intake throttle valve 18 (not a throttle valve) that throttles in accordance with the operating state of the vehicle. To open and close the intake throttle valve 18, a first actuator 19 composed of a negative pressure responsive diaphragm device and a first actuator 19 1 actuator 19
And a first duty solenoid 20 (three-way solenoid valve) for supplying a control negative pressure to the pressure chamber. Here, the first duty solenoid 20 has a first negative pressure supply passage 21 whose upstream end is connected to a vacuum pump (not shown) and a first atmospheric pressure whose upstream end is connected to an air cleaner (not shown). The introduction passage 22 and the first control negative pressure supply passage 23 whose downstream end is connected to the pressure chamber of the first actuator 19.
And are connected. Then, as described later, the first duty solenoid 20 supplies a control negative pressure to the pressure chamber of the first actuator 19 through the first control negative pressure supply passage 23 according to the duty ratio applied from the control unit CU. Then, the opening degree (throttle degree) of the intake throttle valve 18, that is, the intake pipe pressure is controlled.

An EGR passage 25 is provided in order to recirculate a part of the exhaust gas in the exhaust passage 9 to the common intake passage 15, and the EGR passage 25 has an exhaust gas recirculation amount (EGR amount).
An EGR control valve 26 for controlling the engine is provided.
In order to open / close the EGR control valve 26, the second actuator 2 composed of a negative pressure responsive diaphragm device.
7 and a second duty solenoid 28 for supplying a control negative pressure to the pressure chamber of the second actuator 27. Here, the second duty solenoid 28 has a second negative pressure supply passage 29 whose upstream end is connected to a vacuum pump (not shown) and a second large pressure solenoid whose upstream end is connected to an air cleaner (not shown). The atmospheric pressure introduction passage 30 and the second control negative pressure supply passage 31 whose downstream end is connected to the pressure chamber of the second actuator 27 are connected to each other. The second duty solenoid 28 supplies the control negative pressure to the pressure chamber of the second actuator 27 through the second control negative pressure supply passage 31 according to the duty ratio applied from the control unit CU, and the EGR control valve 26. The opening degree (EGR amount), that is, the EGR lift is controlled. In addition, E
The assembly including the GR passage 25, the EGR control valve 26, the second actuator 27, the second duty solenoid 28, etc. corresponds to the "exhaust gas recirculation means" described in the claims.

The control unit CU is composed of a microcomputer, and the "intake control means", "cooling state detection means" and "intake correction control means" described in the claims.
It is a comprehensive control device for the engine DE including and, which is detected by an engine water temperature detected by a water temperature sensor 35, an intake pipe pressure downstream of an intake throttle valve detected by an intake pressure sensor 36, and an EGR position sensor 37. EGR position (EGR lift, that is, EGR amount), crankshaft rotation cycle detected by the cycle sensor 38,
Predetermined control of the engine DE is performed using control information such as the accelerator opening detected by the accelerator sensor 39.

The control method of engine control by the control unit CU will be described below with reference to the flow charts shown in FIGS. This control unit CU
The engine control performed by the main routine (FIG. 3) for controlling the energization of the glow plug 6 and the first interrupt routine (FIG. 4) for controlling the intake pipe pressure, that is, the throttle degree (air throttle amount) of the intake throttle valve 18 are performed. And E of the EGR control valve 26
It comprises a second interrupt routine (FIG. 5) for controlling the GR lift amount (EGR position, that is, EGR amount).

First, the main routine will be described according to the flow chart shown in FIG. 3 and with reference to FIG.
First, in step # 1, the control system is initialized, and then in step # 2, the engine water temperature, the crankshaft rotation cycle, the accelerator opening, the intake pipe pressure, the EGR position (E
GR lift amount) and the like are read as control information.

In step # 3, the engine speed (the reciprocal of the cycle) is calculated from the crankshaft rotation cycle. In step # 4, the rack position (target engine load) is calculated based on the engine speed and the accelerator opening, using a map having the characteristics shown in FIG. 6, for example. Although not shown in this main routine, the fuel injection amount and injection timing of the fuel injection valve 5 are controlled based on this rack position.

In step # 5, the energization time of the glow plug 6, that is, the duty ratio to be applied to the glow plug 6 is calculated based on the engine speed and the rack position using a map such as that shown in FIG. It In step # 6, whether or not it is time to energize the glow plug 6 (timing) is compared / determined. If it is not time to energize (NO), this step # 6 is performed until the energization time comes.
Is repeatedly executed (waiting). If it is determined in step # 6 that it is time to energize the glow plug 6,
(YES), in step # 7, the glow plug 6 is energized according to the duty ratio, and ignition / combustion is achieved. After this, the process returns to step # 2.

The first interrupt routine for controlling the intake pipe pressure, that is, the opening degree of the intake throttle valve 18 (air throttle amount) will be described below with reference to the flowchart shown in FIG. In the engine DE, basically, air is supplied to the combustion chamber 3 without being throttled, and the engine output is controlled by the fuel injection amount of the fuel injection valve 5. However, in this way, as described above (the problem to be solved by the invention), the air supply amount becomes excessive with respect to the fuel supply amount at the time of partial load, particularly at low load, and the combustibility of the fuel decreases, or Due to the decrease of the exhaust gas temperature, there is a problem that the time required to raise the temperature of the exhaust gas purifying catalyst becomes longer when the engine is cold and the emission becomes worse. Therefore, in the present embodiment, the intake pipe pressure, that is, the air throttle amount, is proportionally operated (P operation) and differentiated operation according to the rack position (engine load), the engine speed, and the engine water temperature (cooling degree of the engine). Feedback control is performed by (D operation).

Specifically, first, at step # 11, it is determined whether the operating state of the engine DE is in the intake throttle region by using a map having the characteristics shown in FIG. 8, for example.
That is, it is compared and determined whether or not it is in the region where the intake throttle valve 18 is to be closed (throttled air). As shown in FIG. 8, in this embodiment, basically, an area where the engine speed is low or the rack position (engine load) is small, or both areas are small (hereinafter, these areas are appropriately referred to as a low output area). Is the intake throttle area. That is, in such a low output region, the excess air ratio in the combustion chamber 3 increases, the fuel is dispersed in the combustion chamber 3 and stratification is hindered, and the combustibility of the fuel decreases. Therefore, in such a low output region, the intake throttle valve 18 is closed to throttle the air,
The concentration of the air-fuel mixture around the glow plug 6 is increased to promote the stratified combustion of the fuel and enhance the combustibility.

Further, as is clear from FIG. 8, the intake throttle region is enlarged as the engine water temperature is lower. This is because when the engine is cold (early after the engine starts), the exhaust gas temperature is raised and the exhaust gas purification catalyst is quickly heated to the activation temperature. That is, as described above, since the amount of unburned fuel discharged increases when the engine is cold, the air is throttled in this way to raise the exhaust gas temperature,
The exhaust gas purifying catalyst is raised to an activation temperature at an early stage to promote purification of the unburned fuel to enhance emission performance. However, when the air is throttled in this way, the pumping loss of the engine DE is increased, which leads to deterioration of fuel efficiency. Therefore, when the engine water temperature is high, that is, when it is considered that the exhaust gas purification catalyst has already reached the activation temperature (during warm time), the intake throttle area is reduced to improve fuel efficiency. .

If it is determined in step # 11 that the operating state of the engine DE is not within the intake throttle region,
(NO), there is no need to throttle the air, so skip all steps below. On the other hand, if it is determined in step # 11 that the operating state of the engine DE is in the intake throttle region (YES), the target intake pipe pressure Pt (that is, the target air throttle amount) is calculated in step # 12. In this embodiment, when the operating state of the engine DE is in the intake throttle region, the target intake pipe pressure Pt, that is, the target throttle amount of air, the engine speed, the rack position (engine load),
It is set according to the engine water temperature. Specifically, the target intake pipe pressure Pt is set by the following equation 1.

[Formula 1] Pt = Pb + Pwt …………………………………………………… Equation 1

In Equation 1, Pb is the base pressure (positive) and Pwt is the water temperature correction pressure (negative). Where base pressure P
b is set according to the engine speed and the rack position using a map having the characteristics shown in FIG. 9, for example. As shown in FIG. 9, the base pressure Pb is set lower as the engine speed is lower or as the rack position is smaller (the air throttle amount is larger). That is, as in the description of step # 11, the fuel combustibility decreases as the engine speed decreases or the rack position decreases. Therefore, the air combustibility varies depending on the engine speed and the rack position. Is increased to increase the concentration of the air-fuel mixture around the glow plug 6 to promote stratified combustion and enhance combustibility.

Further, the water temperature correction pressure Pwt is set according to the engine water temperature by using, for example, a map having the characteristics shown in FIG. 10. As shown in FIG. 10, the water temperature correction pressure Pwt is set.
wt is set so that the lower the engine water temperature, the stronger the negative pressure. Therefore, as is clear from the equation 1, the target intake pipe pressure Pt becomes lower (the air throttle amount becomes larger) as the engine water temperature becomes lower. That is, in a manner similar to the description in step # 11, when the engine is cold, the throttle amount of air is increased to raise the exhaust gas temperature, and the exhaust gas purification catalyst is quickly heated to the activation temperature to improve the emission performance. I have to.

Next, at step # 13, the first duty solenoid 20 is operated according to the intake pipe pressure deviation, that is, the deviation of the actual intake pipe pressure from the target intake pipe pressure Pt, and the rate of change of the intake pipe pressure deviation with respect to time. The energization time is calculated. Subsequently, in step # 14, it is compared and determined whether or not it is the time to energize the first duty solenoid 20, and if it is determined to be the time to energize (YES), the first duty solenoid 20 is turned on in step # 15. Power is supplied and the intake pipe pressure is feedback-controlled. If it is determined in step # 14 that it is not the time to energize (N
O), step # 14 is repeatedly executed until the energization time comes, and step # 15 is executed, and then step # 11.
Return to.

In the feedback control of the intake pipe pressure, as shown in FIG. 11, basically, a proportional operation (P operation) for setting the control amount in proportion to the intake pipe pressure deviation is performed. In addition to the operation, differential operation that corrects the control amount in proportion to the rate of change of intake pipe pressure deviation with time
(D motion) is also added. By performing feedback control of the intake pipe pressure in this manner, variations in intake pipe pressure are absorbed and control stability is enhanced. Also, P motion and D
Since this is used together with the operation, it is possible to perform feedback control that anticipates the change tendency of the intake pipe pressure (control amount), that is, to anticipate the future, and reduce the delay in the control operation. Therefore, control responsiveness can be improved while maintaining control stability.

The lift amount of the EGR control valve 26 will be described below with reference to the flowchart shown in FIG.
A second interrupt routine for controlling (EGR position, that is, EGR amount) will be described. In the second interrupt routine, the EGR lift amount (EGR amount) is controlled according to the engine speed, the rack position, and the engine water temperature, and the EGR amount is increased in the low output region to increase the temperature in the combustion chamber 3. It is designed to increase the combustibility of fuel. Also, when the engine is cold, the EGR gas amount is increased to raise the exhaust gas temperature and the exhaust gas purification catalyst is quickly heated to the activation temperature.

First, at step # 21, the target EGR lift amount Lt (target EGR position, that is, target EGR
Quantity) is calculated. In this embodiment, the EGR lift amount Lt
Engine speed, rack position (engine load),
It is set according to the engine water temperature. Specifically, the target EGR lift amount Lt is set by the following equation 2.

[Formula 2] Lt = Lb + Lwt …………………………………………………… Formula 2

In Equation 2, Lb is the base lift amount and Lwt is the water temperature correction lift amount. Here, the base lift amount Lb is set according to the engine speed and the rack position (engine load) using, for example, a map having the characteristics shown in FIG. As shown in FIG. 12, the base lift amount Lb is
Alternatively, the smaller the rack position, the larger the setting.
(The amount of EGR increases). That is, the lower the engine speed or the smaller the rack position, the lower the combustibility of the fuel. Therefore, the EGR is increased to increase the temperature of the air (mixture) in the combustion chamber 3 to improve the combustibility. I have to. A moderate EGR raises the air temperature (mixture temperature) in the combustion chamber 3 to promote the main combustion after ignition and shortens the combustion period, so that the combustion performance is enhanced.

Further, the water temperature correction lift amount Lwt is set in accordance with the engine water temperature by using, for example, a map having the characteristics shown in FIG. 13. As shown in FIG. 13, the water temperature correction lift amount Lwt is The lower the engine water temperature is, the higher the value is set. Therefore, as is clear from Expression 2, the target EGR lift amount Lt is set to be larger (the EGR amount is larger) as the engine water temperature is lower. That is, when the engine is cold, the EGR is increased to raise the exhaust gas temperature and the exhaust gas purifying catalyst is quickly heated to the activation temperature.

Next, at step # 22, the second duty is determined in accordance with the deviation of the EGR lift amount, that is, the deviation of the actual EGR lift amount from the target EGR lift amount Lt, using a map of the characteristics shown in FIG. 14, for example. The energization time to the solenoid 28 is calculated. Then, step # 2
At 3, it is compared and determined whether or not it is time to energize the second duty solenoid 28, and if it is determined that it is time to energize.
(YES) In step # 24, the second duty solenoid 2
8 is energized, and the EGR lift (EGR amount) is feedback-controlled. If it is determined in step # 23 that it is not the time to energize (NO), step # 23 is repeatedly executed until the time to energize, and step # 24 is executed and then the process returns to step # 21. In this second interrupt routine as well, the EGR lift amount (EGR amount) is feedback-controlled, so that the control stability and the control responsiveness are naturally improved.

[0036]

According to the first aspect of the invention, when the engine is cold, the throttle correction amount of the intake throttle valve (air throttle amount) is set to be larger than that during the warm period.
The excess air ratio decreases and the exhaust gas temperature rises. Therefore, the exhaust gas purifying catalyst provided in the exhaust passage can be quickly raised to the activation temperature, and the emission performance is improved.

According to the second aspect of the present invention, when the engine is cold, the intake throttle region is expanded by the intake correction control means, so that the excess air ratio becomes small and the exhaust gas temperature rises. Therefore, the exhaust gas purifying catalyst provided in the exhaust passage can be quickly raised to the activation temperature, and the emission performance is improved.

According to the third aspect of the invention, when the engine is cold, the intake throttle control area is expanded by the intake correction control means, and the throttle amount of the intake throttle valve (air throttle amount) is set to be larger than during warm time. Therefore, the excess air ratio decreases and the exhaust gas temperature rises. Therefore, the exhaust gas purifying catalyst provided in the exhaust passage can be quickly raised to the activation temperature, and the emission performance is improved.

According to the fourth aspect of the invention, when the engine is cold, the EGR gas amount (exhaust gas recirculation amount) is increased by the intake air correction control means as compared with the warm time, so the exhaust gas temperature rises. Therefore, the exhaust gas purification catalyst provided in the exhaust passage can be quickly heated to the activation temperature,
Emission performance is improved.

According to the fifth invention, basically the same action and effect as any one of the first to fourth inventions can be obtained. Furthermore, since the air throttle amount or the EGR amount is feedback-controlled, variations in the control amount are absorbed,
Control accuracy is improved.

According to the sixth invention, basically, the same operation and effect as those of the fifth invention can be obtained. Furthermore, since the feedback control is performed by the proportional operation and the derivative operation, the control is performed in consideration of the change in the control amount, and the control stability and the control responsiveness are improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of first to sixth inventions corresponding to claims 1 to 6.

FIG. 2 is a system configuration diagram of a direct injection engine according to the present invention.

FIG. 3 is a flowchart of a main routine in engine control.

FIG. 4 is a flowchart of a first interrupt routine in engine control.

FIG. 5 is a flowchart of a second interrupt routine in engine control.

FIG. 6 is a diagram showing a characteristic of a rack position in a main routine with respect to an engine speed and an accelerator opening.

FIG. 7 is a map for calculating an energization time (duty ratio) of a glow plug in a main routine.

FIG. 8 is a diagram showing characteristics of an intake throttle region in a first interrupt routine with respect to a rack position, an engine speed, and an engine water temperature.

FIG. 9 shows the base pressure in the first interrupt routine,
It is a figure which shows the characteristic with respect to a rack position and an engine speed.

FIG. 10 is a diagram showing a characteristic of a water temperature correction pressure with respect to an engine water temperature in a first interrupt routine.

FIG. 11 shows the energization time of the first duty solenoid,
It is a figure which shows the characteristic with respect to an intake pipe pressure deviation.

FIG. 12 is a diagram showing a characteristic of a base lift amount with respect to a rack position and an engine speed in a second interruption routine.

FIG. 13 is a diagram showing characteristics of a water temperature correction lift amount in a second interrupt routine with respect to engine water temperature.

FIG. 14 is a graph showing the energization time of the second duty solenoid,
It is a figure which shows the characteristic with respect to EGR lift amount deviation.

[Explanation of symbols]

 DE ... Engine CU ... Control unit 3 ... Combustion chamber 5 ... Fuel injection valve 6 ... Glow plug 18 ... Intake throttle valve 19 ... First actuator 20 ... First duty solenoid 25 ... EGR passage 26 ... EGR control valve 27 ... Second actuator 28 ... Second duty solenoid 35 ... Water temperature sensor

Claims (6)

[Claims] 1. A direct injection engine provided with a fuel supply means for directly supplying fuel to a combustion chamber, and an intake throttle valve capable of restricting an intake amount, and the intake throttle valve depending on an operating state of the engine. Intake control means for controlling the intake throttle amount, cold state detection means for detecting the cold state of the engine, and when the cold state detection means detects that the engine is in the cold state A direct-injection engine, which is provided with intake correction control means for correcting and controlling the intake throttle valve so as to increase. 2. A direct injection engine provided with a fuel supply means for directly supplying fuel to a combustion chamber, and an intake throttle valve capable of restricting an intake amount, and an engine operating state within a predetermined intake throttle region. In some cases, the intake control means for controlling the intake throttle valve to throttle the intake air amount, the cold state detection means for detecting the cold state of the engine, and the cold state detection means have detected that the engine is in the cold state. Sometimes, a direct injection engine characterized by further comprising intake correction control means for correcting the intake throttle region in the expansion direction. 3. A direct injection engine provided with fuel supply means for directly supplying fuel to a combustion chamber, and an intake throttle valve capable of restricting an intake air amount, and an engine operating state within a predetermined intake throttle region. In some cases, the engine may be in the cold state by the intake control means for controlling the intake throttle amount of the intake throttle valve according to the operating state, the cold state detecting means for detecting the cold state of the engine, and the cold state detecting means. When detected, an intake correction control means is provided for correcting the intake throttle region in the expansion direction and correcting and controlling the intake throttle valve so that the intake throttle amount becomes larger than in the normal state. Direct injection engine. 4. A direct injection engine provided with fuel supply means for directly supplying fuel to a combustion chamber, and an exhaust gas recirculation means capable of recirculating a part of exhaust gas to an intake system, and engine operation. Intake control means for controlling the exhaust gas recirculation amount of the exhaust gas recirculation means according to the state, cold machine state detection means for detecting the cold state of the engine, and detection of the engine in the cold state by the cold state detection means A direct-injection engine, comprising: an intake correction control means for correcting and controlling the exhaust gas recirculation means so that the exhaust gas recirculation amount becomes larger than that at the normal time when the engine is operated. 5. The direct injection engine according to any one of claims 1 to 4, wherein the intake control means and the intake correction control means control the controlled object by feedback control. Direct-injection engine. 6. The direct injection engine according to claim 5, wherein the intake control means and the intake correction control means perform feedback control based on a proportional operation proportional to the deviation and a differential operation proportional to the deviation change rate. A direct-injection engine characterized by being designed to be operated.