JP2010196673A - Catalyst warming-up device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To early increase the temperature of a catalyst converter while solving problems with cost, space layout and reliability. <P>SOLUTION: This catalyst warming-up device includes the catalyst converter 13 installed in an exhaust passage 5, and a gas fuel injection valve 9 for supplying hydrogen gas into a combustion chamber 3. When the activity of the catalyst converter 13 is low, the hydrogen gas injected by the gas fuel injection valve 9 is introduced into the catalyst converter 13 in an unburnt condition. Thus, the unburnt hydrogen can be supplied to the catalyst converter 13 to early increase the temperature of the catalyst converter 13 with the oxidation reaction of the hydrogen involving heat generation on the catalyst converter 13 while solving problems with cost, space layout and reliability. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a catalyst warm-up device for an internal combustion engine.

  In an internal combustion engine that purifies harmful exhaust components by oxidation, reduction, and adsorption effects of a catalytic converter, the exhaust purification ability of the catalyst, that is, the catalytic activity, has a strong correlation with temperature. In particular, the exhaust performance at the cold start when the catalyst is cold is greatly affected by the warm-up performance of the catalyst. For this reason, generally, means for increasing the exhaust gas temperature by retarding the ignition timing at the time of starting and prematurely warming up the catalyst by passing a high-temperature gas is taken. However, in recent years, it has become difficult to respond to the stricter exhaust emission regulations with the above-mentioned means alone.Additional injection is performed late in the expansion stroke to increase the amount of unburned fuel in the exhaust gas, and the unburned fuel is oxidized on the catalyst. By doing so, a method of speeding up the catalyst warm-up has been implemented. However, there has been a problem that some unburned fuel slips through without being reacted on the catalyst. Therefore, hydrogen, which has a simple structure and a high reaction rate, is attracting attention, not a hydrocarbon fuel having a complicated molecular structure such as gasoline or light oil.

  For example, Patent Document 1 proposes a means for accelerating the warm-up of the catalyst by installing a hydrogen supply path and a spark plug in front of the catalyst and burning the catalyst in front of the catalyst.

JP-A-6-117239

  However, the dedicated hydrogen supply path for catalyst warm-up has a high burden on cost and space layout because there is no other use once the warm-up is complete, and depending on the operating load, it continues to be exposed to high temperatures close to 1000 ° C. The issue of sex is also great.

  Therefore, the present invention is a combination of a hydrogen supply means for supplying hydrogen to the catalyst and a means for supplying hydrogen to the combustion chamber in an internal combustion engine in which hydrogen is mixed with hydrocarbon fuel or burned alone, thereby reducing cost and space layout. Resolve reliability issues.

  Accordingly, the present invention stops ignition of the combustible gas when the activity of the catalytic converter installed in the exhaust passage is low in an internal combustion engine that operates using a combustible gas containing hydrogen as fuel or part of the fuel. The combustible gas is introduced into the catalytic converter.

  According to the present invention, the means for supplying hydrogen to the catalytic converter and the means for supplying hydrogen to the combustion chamber can be used together to solve the problem of cost, space layout, and reliability, Can be used to warm up. That is, it becomes possible for hydrogen to pass through the exhaust valve without being burned and to be supplied to the catalytic converter, while solving the problems of cost, space layout, and reliability, while generating heat generated on the catalytic converter. The temperature of the catalytic converter can be raised early by the oxidation reaction.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows the outline of the system configuration | structure of the catalyst warm-up apparatus of the internal combustion engine which concerns on this invention. Explanatory drawing which showed typically 1st Embodiment of this invention. The flowchart which shows the flow of control in 1st Embodiment of this invention. Explanatory drawing which showed typically 2nd Embodiment of this invention. The flowchart which shows the flow of control in 2nd Embodiment of this invention. Explanatory drawing which showed typically 3rd Embodiment of this invention. The flowchart which shows the flow of control in 3rd Embodiment of this invention. Explanatory drawing which shows the outline of the system configuration | structure in 4th Embodiment of the catalyst warm-up apparatus of the internal combustion engine which concerns on this invention.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram showing an outline of the system configuration of a catalyst warm-up device for an internal combustion engine according to the present invention.

  An intake passage 5 is connected to the combustion chamber 3 formed by the piston 2 of the internal combustion engine 1 through an intake valve 4, and an exhaust passage 7 is connected through an exhaust valve 6.

  An ignition plug 8 and a gas fuel injection valve 9 are arranged in the combustion chamber 3. That is, the gas fuel injection valve 9 is arranged for each cylinder. The gas fuel injection valve 9 is supplied with hydrogen from a hydrogen tank 10.

  In the intake passage 5, a gasoline injection valve 11 for injecting gasoline as the main fuel is disposed. Gasoline is supplied from a gasoline tank 12 to the gasoline injection valve 11.

  A catalytic converter 13 for purifying exhaust gas is interposed downstream of the exhaust passage 7. A catalytic temperature sensor 14 that detects the catalyst temperature of the catalytic converter 13, that is, the temperature of the catalytic converter 13, is attached to the catalytic converter 13. The detection value of the catalyst temperature sensor 14 is input to the ECU 15.

  The ECU 15 is a well-known digital computer having a CPU, a ROM, a RAM, and an input / output interface, and based on detection signals from various sensors, the fuel injection amount and injection timing of the gas fuel injection valve 9 and the gasoline injection valve 11. The ignition timing of the spark plug 8 is controlled.

  In the first embodiment of the present invention, when the driver determines that the catalytic activity of the catalytic converter 13 is low when the engine key is turned on, that is, the temperature of the catalytic converter 13 is set to a predetermined temperature. If not, in order to activate the catalytic converter 13, as shown in FIG. 2, hydrogen gas is injected from the gas fuel injection valve 9 of the cylinder in which the exhaust valve 6 is open, and the catalytic converter 13 is charged with hydrogen. Supply.

  As a result, hydrogen can pass through the exhaust valve 6 without being burned, and unburned hydrogen can be supplied to the catalytic converter 13, so that the catalyst is generated by the oxidation reaction of hydrogen accompanied by heat generation on the catalytic converter 13. The temperature of the converter 13 can be raised early. Further, since hydrogen gas is injected into the cylinder in which the exhaust valve 6 is open, the cylinder is filled with hydrogen in the cylinder in which the exhaust valve 6 is closed, causing torque fluctuations at start-up and backflow to the intake side. It can be prevented from becoming a cause of flashback.

  When the temperature of the catalytic converter 13 reaches a predetermined temperature set in advance, cranking start is started. In other words, the lower the activity of the catalytic converter 13, the longer the period for introducing unburned hydrogen gas into the catalytic converter 13. Therefore, an excessive increase in the temperature of the catalytic converter 13 can be suppressed.

  If the predetermined temperature is set to the ignition temperature of the hydrogen gas, hydrogen burns in the exhaust passage 7 using the catalytic converter 13 as an ignition source and dissipates heat from the pipe, and the temperature rising energy of the catalytic converter 13 is lost. This can be prevented.

  FIG. 3 is a flowchart showing the flow of control in the first embodiment.

  In step 11 (hereinafter, simply referred to as S), it is determined whether or not the key is turned on by operating the engine key by the driver, and when it is determined that the key is turned on, that is, the engine start timing. If it is determined, the process proceeds to S12, and if not, the current routine is terminated. Here, in S11, n = 1. n distinguishes which cylinder of the internal combustion engine 1 is, and takes a natural number equal to or less than the number of cylinders of the internal combustion engine 1. That is, n = 1 means the first cylinder of the internal combustion engine 1. In the first embodiment, since the internal combustion engine 1 is a V-type 6 cylinder, n is a natural number of 6 or less.

  In S12, it is determined whether or not the activity of the catalytic converter 13 is low, that is, whether or not the catalytic converter 13 is activated. If activated, the process proceeds to S18 and is not activated (the activity is low). ), The process proceeds to S13. More specifically, in S12, it is determined whether or not the temperature of the catalytic converter 13 has reached a predetermined temperature set in advance. If the temperature of the catalytic converter 13 is equal to or higher than the predetermined temperature set, the process proceeds to S18. When the temperature of the catalytic converter 13 is lower than a predetermined temperature set in advance, the process proceeds to S13.

  In S13, it is determined whether or not the exhaust valve 6 of the nth cylinder is open. If the exhaust valve 6 of the nth cylinder is open, the process proceeds to S14, and if not, the process proceeds to S15.

  In S14, hydrogen gas is injected from the gas fuel injection valve 9 of the nth cylinder, and the process proceeds to S15.

  In S15, the process proceeds to S16 with n = n + 1. If it is determined in S16 that n is larger than 6, the process proceeds to S17, and the process proceeds to S12 with n = 1. If n is determined to be 6 or less in S16. Proceed to S12.

  That is, at the start of the internal combustion engine 1, it is sequentially determined whether the exhaust valve 6 is open for each cylinder of the internal combustion engine 1 until the temperature of the catalytic converter 13 reaches a predetermined temperature set in advance. In each open cylinder, hydrogen gas is injected from the gas fuel injection valve 9 each time.

  Then, when the temperature of the catalytic converter 13 becomes equal to or higher than a predetermined temperature set in advance, the process proceeds to S18 to start cranking, and ignition by the spark plug 8 is started in S19. In addition, if it progresses to S18, injection of the hydrogen gas from the gas fuel injection valve 9 will be complete | finished.

  Hereinafter, although other embodiment of this invention is described, about the component same as 1st Embodiment mentioned above, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  Next, a second embodiment of the present invention will be described. The second embodiment has substantially the same configuration as the first embodiment described above, but a gas fuel injection valve 9 is provided in the intake passage 5 as shown in FIG. When it is determined that the catalytic activity of the catalytic converter 13 is low when the engine key is turned on by the driver, cranking is started and hydrogen gas is injected from the gas fuel injection valve 9 to supply hydrogen to the catalytic converter 13. Supply. At this time, fuel injection is not performed from the gasoline injection valve 11 disposed in the combustion chamber 3, and the spark plug 8 is not ignited. That is, motoring is performed until the catalytic converter 13 is activated, and the hydrogen gas injected from the gas fuel injection valve 9 is supplied to the catalytic converter 13.

  Also in the second embodiment, the temperature of the catalytic converter 13 can be raised at an early stage by the oxidation reaction of hydrogen as in the first embodiment described above.

  FIG. 5 is a flowchart showing a control flow in the second embodiment.

  In step 21, it is determined whether or not the key has been turned on by operating the engine key by the driver. If it is determined that the key has been turned on, that is, if it is determined that it is the timing for starting the engine, The process proceeds to S22, and if not, the current routine is terminated.

  In S22, it is determined whether or not the activity of the catalytic converter 13 is low, that is, whether or not the catalytic converter 13 is activated. If activated, the process proceeds to S25 and is not activated (the activity is low). ), The process proceeds to S23. In S23, cranking is started, and the process proceeds to S24. In S24, hydrogen gas injection is started, and the process proceeds to S22.

  That is, when the internal combustion engine 1 is started, motoring is performed until the temperature of the catalytic converter 13 reaches a predetermined temperature set in advance, and only hydrogen gas is injected during the motoring, so that the catalytic converter 13 is injected. Supply hydrogen.

  Then, when the temperature of the catalytic converter 13 becomes equal to or higher than a predetermined temperature set in advance, the process proceeds to S25 and gasoline injection is started and ignition by the spark plug 8 is started. In addition, if it progresses to S25, the injection of the hydrogen gas from the gas fuel injection valve 9 will be complete | finished.

  Next, a third embodiment of the present invention will be described. The third embodiment has substantially the same configuration as that of the first embodiment described above, but the gasoline injection valve 11 is arranged so that fuel can be directly injected into the cylinder of each cylinder. Gas fuel injection valves 9 for injecting hydrogen gas are arranged in the second and fifth cylinders.

  When it is determined that the catalytic activity of the catalytic converter 13 is low when the engine key is turned on by the driver, the gasoline injection and ignition of the second and fifth cylinders are stopped as shown in FIG. For the No. 5 cylinder and No. 5 cylinder, only hydrogen gas is injected until the catalytic converter 13 is activated. That is, until the catalytic converter 13 is activated, the cylinders of the second and fifth cylinders are deactivated, and the hydrogen gas injected into the second and fifth cylinders that are deactivated is supplied to the catalytic converter 13.

  Also in such 3rd Embodiment, similarly to 1st Embodiment mentioned above, the temperature of the catalytic converter 13 can be raised early.

  FIG. 7 is a flowchart showing a control flow in the third embodiment.

  In step 31, it is determined whether or not the key has been turned on by operating the engine key by the driver. If it is determined that the key has been turned on, that is, if it is determined that it is the engine start timing, The process proceeds to S32, and if not, the current routine is terminated.

  In S32, it is determined whether or not the activity of the catalytic converter 13 is low, that is, whether or not the catalytic converter 13 is activated. If activated, the process proceeds to S36 and is not activated (the activity is low). ), The process proceeds to S33.

  In S33 to S35, the cylinder is stopped and the hydrogen gas is injected in the cylinder in which the cylinder is stopped. Specifically, in the third embodiment, the cylinders of the second cylinder and the fifth cylinder of the V-type six-cylinder internal combustion engine 1 are stopped. Specifically, for the second and fifth cylinders, hydrogen gas is injected from the gas fuel injection valve 9, but gasoline is not injected from the gasoline injection valve 11, and ignition by the spark plug 8 is also performed. Not implemented. For the first cylinder, the third cylinder, the fourth cylinder, and the sixth cylinder, gasoline is injected from the gasoline injection valve 11 and ignited by the spark plug 8, but hydrogen gas is not supplied.

  When the temperature of the catalytic converter 13 is equal to or higher than a predetermined temperature set in advance, the process proceeds to S36, in which gasoline is injected from the gasoline injection valve 11 and ignition by the ignition plug 8 is performed in all cylinders, and the gas fuel injection valve From 9, normal start is started without hydrogen gas injection.

  Next, a fourth embodiment of the present invention will be described. The fourth embodiment has substantially the same configuration as the first embodiment described above, but as shown in FIG. 8, a gas fuel injection valve 9 is provided in the intake passage 5 and a gasoline injection valve 11 is provided for each cylinder. The combustion chamber 3 is provided.

  A fuel reformer 20 is disposed downstream of the catalytic converter 13 as fuel reforming means. The fuel reformer 20 is a fuel converter that uses the heat of the exhaust gas downstream of the catalytic converter 13, and generates a combustible gas containing hydrogen from gasoline by a dehydrogenation reaction or decomposition reaction on the catalyst. . The reformed gas generated by the fuel reformer 20 is stored in the reformed gas tank 21. The reformed gas in the reformed gas tank 21 is injected from a gas fuel injection valve 9 provided in the intake passage 5. The fuel reformer 20 is provided with a temperature sensor 22 that detects the catalyst temperature in the fuel reformer 20, and the detected value of the temperature sensor 22 is input to the ECU 15.

  In the fourth embodiment, since the reforming efficiency is low when the catalyst temperature of the fuel reformer 20 is equal to or lower than the activation temperature, the waste heat cannot be sufficiently recovered and the system efficiency is lowered or the reforming is performed. The amount of gas generated is insufficient and high-efficiency combustion using the reformed gas cannot be performed. Therefore, when the catalyst temperature of the fuel reformer 20 is lower than the activation temperature, if the catalyst converter 13 is warmed up by a method such as that of the first to third embodiments described above, the temperature of the exhaust gas The amount of reformed gas generated can be prevented from being insufficient.

  The method of increasing the temperature of the catalytic converter 13 at an early stage is not limited to the method of each embodiment described above. For example, when the activity of the catalytic converter 13 is low when the internal combustion engine 1 is started, In a predetermined period, ignition is stopped for each combustion cycle, and when the ignition is stopped, unburned hydrogen gas is supplied to the catalytic converter 13 by injecting hydrogen gas from the gas fuel injection valve. The temperature of the catalytic converter 13 can be raised early.

  Further, in each of the above-described embodiments, when the internal combustion engine 1 is stopped, by setting the operation in which the fuel injection is stopped to be performed for at least one cycle, oxygen necessary for catalyst warm-up around the catalytic converter 13 is set. Can be reliably distributed, and when the combustible gas containing hydrogen is supplied to the catalytic converter 13, the temperature of the catalytic converter 13 can be reliably increased.

  The technical ideas of the present invention that can be grasped from the above-described embodiments will be listed together with their effects.

  (1) A catalyst warm-up device for an internal combustion engine includes a catalytic converter installed in an exhaust passage for the purpose of purifying exhaust in an internal combustion engine that operates using a combustible gas containing hydrogen as fuel or a part of the fuel, and combustion The chamber is provided with an injection valve capable of supplying the combustible gas, and when the catalytic converter has low activity, the ignition to the combustible gas is stopped and the combustible gas is introduced into the catalytic converter. This makes it possible to supply unburned hydrogen to the catalytic converter by passing through the exhaust valve with unburned hydrogen. The temperature of the catalytic converter is increased by the oxidation reaction of hydrogen accompanied by heat generation on the catalytic converter. It can be raised early.

  (2) The catalyst warm-up device for an internal combustion engine according to (1), wherein the combustion chamber has an injection valve capable of supplying a combustible gas containing hydrogen, and the combustible gas is provided only in a cylinder in which the exhaust valve is open. Inject. As a result, it is possible to prevent hydrogen from being filled into the cylinder in the cylinder in which the exhaust valve is closed and causing torque fluctuation at the time of start-up or backflow to the intake side to cause backfire.

  (3) In the catalyst warm-up device for an internal combustion engine according to (1) or (2), when the internal combustion engine is stopped, the operation in which the fuel injection is stopped is performed for at least one cycle. Even if a combustible gas containing hydrogen is supplied to the catalytic converter, if oxygen is insufficient, the reaction becomes insufficient, and the catalytic converter may not be sufficiently heated. Accordingly, oxygen necessary for warming up the catalyst can be reliably distributed around the catalytic converter, and when the combustible gas containing hydrogen is supplied to the catalytic converter, the temperature of the catalytic converter can be reliably increased.

  (4) In the catalyst warm-up device for an internal combustion engine according to (1), when the activity of the catalytic converter is low, ignition is stopped every predetermined combustion period for a predetermined period. Thus, it is possible to start immediately with the key ON and supply unburned hydrogen to the catalytic converter while operating.

  (5) In the catalyst warm-up device for an internal combustion engine according to (1), when the activity of the catalytic converter is low, ignition of some cylinders is stopped for a predetermined period. Thus, it is possible to start immediately with the key ON and supply unburned hydrogen to the catalytic converter while operating.

  (6) In the catalyst warm-up device for an internal combustion engine according to any one of (1) to (5), the period during which the combustible gas is introduced into the catalytic converter is increased as the activity of the catalytic converter is lower. . By setting the hydrogen supply period for warming up the catalytic converter based on the catalytic activation state, it is possible to suppress the consumption of hydrogen and suppress an excessive increase in the temperature of the catalytic converter.

  (7) In the catalyst warm-up device for an internal combustion engine according to any one of (1) to (6), there is provided catalyst temperature detection means capable of detecting the temperature of the catalytic converter, and the temperature of the catalytic converter is When the temperature exceeds a predetermined temperature, the introduction of the combustible gas into the catalytic converter is stopped. When the catalytic converter reaches the predetermined temperature, the hydrogen supply for warming up the catalytic converter is stopped, so that the catalytic converter is used as an ignition source and hydrogen is burned in the exhaust pipe to dissipate the heat from the pipe. It is possible to prevent energy from being lost.

  (8) In the catalyst warm-up device for an internal combustion engine according to (7), the predetermined temperature is an ignition temperature of the combustible gas.

  (9) The catalyst warm-up device for an internal combustion engine according to any one of (1) to (9), wherein the exhaust gas downstream of the catalytic converter is a main heat source and the dehydrogenation reaction or decomposition reaction on the catalyst. When the catalyst temperature of the catalyst is lower than a predetermined temperature, ignition of the combustible gas is stopped, and the combustible gas is Introduced in catalytic converter. In an internal combustion engine having a fuel reforming means, if the catalyst temperature of the fuel reforming means is lower than the activation temperature, the reforming efficiency is low, so that waste heat cannot be sufficiently recovered and the system efficiency is lowered, or the reformed gas There is a problem that high-efficiency combustion using the reformed gas cannot be performed due to a shortage of the amount of produced. Therefore, when the temperature of the reforming catalyst of the fuel reforming means falls below the activation temperature, the above-mentioned problem can be solved by stopping ignition of the combustible gas and introducing the combustible gas into the catalytic converter. it can.

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Piston 3 ... Combustion chamber 4 ... Intake valve 5 ... Intake passage 6 ... Exhaust valve 7 ... Exhaust passage 8 ... Spark plug 9 ... Gas fuel injection valve 10 ... Hydrogen tank 11 ... Gasoline injection valve 12 ... Gasoline tank 13 ... Catalytic converter 14 ... Catalyst temperature sensor 15 ... ECU

Claims (9)

In an internal combustion engine that operates using a combustible gas containing hydrogen as fuel or a part of fuel, a catalytic converter installed in an exhaust passage for the purpose of purifying exhaust, and an injection valve capable of supplying the combustible gas to a combustion chamber Equipped,
A catalyst warm-up device for an internal combustion engine, wherein when the activity of the catalytic converter is low, ignition of the combustible gas is stopped and the combustible gas is introduced into the catalytic converter.   2. The catalyst warming of an internal combustion engine according to claim 1, wherein an injection valve capable of supplying a combustible gas containing hydrogen is provided in a combustion chamber, and the combustible gas is injected only into a cylinder having an open exhaust valve. Machine equipment.   The catalyst warm-up device for an internal combustion engine according to claim 1 or 2, wherein when the internal combustion engine is stopped, the operation in which the fuel injection is stopped is performed for at least one cycle.   2. The catalyst warm-up device for an internal combustion engine according to claim 1, wherein when the activity of the catalytic converter is low, ignition is stopped every predetermined combustion period for a predetermined period.   2. The catalyst warm-up device for an internal combustion engine according to claim 1, wherein ignition of some cylinders is stopped for a predetermined period when the activity of the catalytic converter is low.   The catalyst warm-up device for an internal combustion engine according to any one of claims 1 to 5, wherein a period during which the combustible gas is introduced into the catalytic converter is lengthened as the activity of the catalytic converter is low.   It has a catalyst temperature detecting means capable of detecting the temperature of the catalytic converter, and stops introducing the combustible gas into the catalytic converter when the temperature of the catalytic converter exceeds a predetermined temperature. The catalyst warm-up device for an internal combustion engine according to any one of claims 1 to 6.   The catalyst warm-up device for an internal combustion engine according to claim 7, wherein the predetermined temperature is an ignition temperature of the combustible gas.   Fuel reforming means capable of generating combustible gas containing hydrogen by a dehydrogenation reaction or decomposition reaction on the catalyst using exhaust gas downstream of the catalytic converter as a main heat source, and the catalyst temperature of the catalyst is predetermined 9. The internal combustion engine catalyst warm-up according to claim 1, wherein the ignition of the combustible gas is stopped and the combustible gas is introduced into the catalytic converter. Machine equipment.

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