JP2001182601A - Early warm-up control device for exhaust emission control catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To early warm up a catalyst through the combustion heat of afterburning by generating the afterburning within an exhaust pipe without providing an ignition device in the exhaust pipe. SOLUTION: Cylinder-reducing running is conducted at the time of early warming up control for a catalyst, wherein ignition timing is spark-delayed to control a rich component such as HC, CO, etc., in exhaust gas so as to be raized to combustible exhaust gas temperature in an exhaust pipe 16, and also fuel injection to a partial cylinder is stopped, and the engine 11 is operated by remaining cylinders (running cylinder) that is cylinder-reduced running. Consequently the rich component in high- temperature exhaust gas exhausted from the running cylinders in mixed with oxygen in unburnt air exhaust from the injection-stopped cylinder, to generate after burning in the pipe 16 on the upstream side of a catalyst 17, to warm up a catalyst 17 by the burning heat of the afterburning. In the cylinder-reduced running, the air-fuel ratio of mixed air to be supplied to the respective running cylinders is controlled to nearby a theoretical air-fuel ratio or to a lean side slightly, and also plural time ignition (multiple ignition) is made in one time combustion stroke in the respective running cylinders.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an early warm-up control device for an exhaust gas purifying catalyst for quickly warming up a catalyst for purifying exhaust gas of an internal combustion engine.

[0002]

2. Description of the Related Art In recent years, general gasoline engine vehicles have
A three-way catalyst is provided in the exhaust pipe to purify HC (hydrocarbon), CO (carbon monoxide), NOx (nitrogen oxide) and the like in the exhaust gas. However, at the time of cooling immediately after the start, the three-way catalyst has not been heated to the activation temperature and is in an inactive state, so that the exhaust gas cannot be sufficiently purified by the three-way catalyst and the exhaust emission deteriorates.

As a countermeasure, in recent years, it has been known that the catalyst is quickly warmed to the activation temperature by performing early catalyst warm-up control such as ignition retard control at the time of cold start to increase the temperature of exhaust gas. However, recently, in order to further enhance the catalyst warm-up performance, as disclosed in JP-A-9-96216,
During early catalyst warm-up control, fuel injection to some of the cylinders of the engine (hereinafter referred to as "injection stopped cylinders") is stopped to increase the oxygen concentration (the amount of unburned air) in the exhaust gas and to the remaining operating cylinders. HC, C in exhaust gas by increasing the fuel injection amount of
It has been proposed to increase a rich component such as O, ignite exhaust gas by an ignition device such as a glow plug provided in the exhaust pipe, generate afterburning in the exhaust pipe, and warm up the catalyst with the combustion heat. .

[0004]

However, in the above-mentioned known example, it is necessary to provide an ignition device such as a glow plug in the exhaust pipe in order to generate afterburning in the exhaust pipe. Disadvantage.

[0005] The present invention has been made in view of such circumstances, and accordingly, an object thereof is to provide an after-burn in the exhaust gas passage without providing an ignition device in the exhaust gas passage to quickly warm the catalyst. An object of the present invention is to provide an early warm-up control device for an exhaust gas purifying catalyst, which can achieve both a simplified configuration, low cost, and improved catalyst warm-up performance.

[0006]

According to a first aspect of the present invention, there is provided an apparatus for controlling the early warm-up of an exhaust gas purifying catalyst according to the present invention. The retard control is performed so that the rich component in the exhaust gas is heated to a temperature at which the exhaust gas can be combusted in the exhaust gas passage, and the reduced cylinder operation control means controls a part of the cylinders (hereinafter referred to as “injection stopped cylinders”). The fuel injection is stopped, and the reduced cylinder operation for operating the internal combustion engine in the remaining cylinders (hereinafter referred to as “operating cylinders”) is performed. With this configuration, during the early catalyst warm-up control, the exhaust gas discharged from the operating cylinder is heated to a temperature at which combustion can be performed in the exhaust gas passage by the ignition retard control. When a rich component such as CO is mixed with the oxygen of the unburned air discharged from the injection stop cylinder, afterburning naturally occurs in the exhaust gas passage, and the combustion heat warms up the catalyst. As a result, the catalyst can be warmed up early after the start, and an ignition device for igniting the exhaust gas is not required, so that the configuration can be simplified and the cost can be reduced.

[0007] Immediately after the start of the internal combustion engine in which the early catalyst warm-up control is performed, the internal combustion engine is also in the process of warming up.
The amount of HC in the exhaust gas tends to increase. Therefore, if the air-fuel ratio of the air-fuel mixture supplied to the operating cylinder is controlled to be rich during the early catalyst warm-up control, the amount of HC in the exhaust gas discharged from the operating cylinder becomes the oxygen of the unburned air discharged from the injection stopped cylinder. There is a possibility that the amount of HC emission to the atmosphere may increase due to an excess with respect to the amount.

Therefore, it is preferable to control the air-fuel ratio of the air-fuel mixture supplied to the operating cylinder during the reduced cylinder operation to a value close to the stoichiometric air-fuel ratio or slightly lean. In this way, the amount of HC in the exhaust gas of the operating cylinder does not become excessive, and is reduced to the minimum amount of HC necessary for early warm-up (after-burning) of the catalyst. As a result, HC in the exhaust gas of the operating cylinder
Can be sufficiently combusted with the oxygen of the unburned air discharged from the injection stop cylinder, and the amount of HC discharged into the atmosphere during early catalyst warm-up control can be reduced.

Further, in the operating cylinder during the reduced cylinder operation, there is a possibility that the combustion stability may be reduced by the ignition retard control, so that one combustion stroke of the operating cylinder during the reduced cylinder operation is performed. During this time, a plurality of ignitions (multiple ignitions) may be executed. With this configuration, the combustion state of the operating cylinder can be stabilized by the multiple ignitions while performing the ignition retard control, and the torque fluctuation and engine vibration due to unstable combustion can be suppressed.

In this case, the ignition retard control (exhaust gas temperature raising control) may be started after the reduced-cylinder operation is started. The reduced cylinder operation may be started simultaneously with or after the start of the retard control. If the reduced cylinder operation is started prior to the ignition retard control, the catalyst early warm-up control can be performed while reducing the amount of HC in the exhaust gas by the reduced cylinder operation. It is possible to reduce the amount of HC discharged into the atmosphere. On the other hand, if the reduced cylinder operation is started at the same time as or after the ignition retard control is started, the start timing of the reduced cylinder operation can be delayed as compared with the case of the fourth embodiment. The reduced cylinder operation can be started under a more stable combustion state than in the case of the fourth aspect, and the torque fluctuation and engine vibration due to the reduced cylinder operation can be reduced.

From the viewpoint of early warm-up of the catalyst, it is desirable to start the ignition retard control and the reduced cylinder operation as soon as possible. However, if the reduced cylinder operation is started at a time when the combustion state is not sufficiently stabilized, torque fluctuation, Engine vibration increases.

Therefore, the start timing of the reduced-cylinder operation may be changed according to the operation state after the start. With this configuration, the reduced cylinder operation can be started after the combustion state is stabilized to some extent, and the torque fluctuation and engine vibration due to the reduced cylinder operation can be reduced. In addition, if the combustion state is quickly stabilized, the reduced-cylinder operation (catalyst warm-up due to afterburning) can be started earlier accordingly.
It is possible to achieve both a reduction in torque fluctuation and the like due to the reduced cylinder operation and an earlier catalyst warm-up time.

Incidentally, the injection stop cylinder during the reduced cylinder operation is:
The cylinder may be fixed to a specific cylinder. However, in such a case, the torque fluctuation and the engine vibration due to the injection stop cylinder occur at the same timing in each cycle, and the driver may feel uncomfortable.

As a countermeasure, the injection stop cylinder may be sequentially changed during the reduced cylinder operation. In this way, the torque fluctuation due to the injection stop cylinder can be dispersed to make it difficult for the driver to feel, and the reduced cylinder operation can be performed without giving the driver discomfort.

Further, when the present invention is applied to a system having variable valve timing means for changing the valve timing of an exhaust valve of an internal combustion engine, the exhaust of the injection stopped cylinder during the reduced cylinder operation may be performed. The valve timing of the valve may be changed according to the valve timing of the exhaust valve of the operating cylinder. With this configuration, during the reduced-cylinder operation, the discharge timing of the unburned air from the injection-stop cylinder is adjusted in accordance with the discharge timing of the high-temperature exhaust gas from the operating cylinder, and the unburned air is discharged at the junction of the exhaust manifold. The air and the high-temperature exhaust gas can be surely merged so that the two can be sufficiently mixed, and the after-burning of the rich component of the exhaust gas can be promoted.

When the present invention is applied to a system having variable valve timing means for changing the valve timing of the intake valve and the exhaust valve, the intake valve of the operating cylinder may be operated during the reduced cylinder operation. Alternatively, the valve timing, fuel injection timing, and ignition timing of the exhaust valve may be controlled at crank angle intervals obtained by dividing 720 ° C. by the number of operating cylinders. If you do this,
During the reduced-cylinder operation, an explosion of each operating cylinder can be generated at every fixed crank angle obtained by dividing 720 ° C. by the number of operating cylinders, similar to an engine having the same number of cylinders as the number of operating cylinders. It is possible to operate with a simple combustion cycle, and it is possible to effectively reduce torque fluctuation and engine vibration due to reduced cylinder operation.

[0017]

[Embodiment (1)] An embodiment (1) of the present invention will be described below with reference to FIGS.
As shown in FIG. 1, an intake pipe 12 of an engine 11 which is an internal combustion engine is provided with a throttle valve 13 for adjusting a throttle opening, and near an intake port of an intake manifold 14 for introducing air to each cylinder. A fuel injection valve 15 for injecting fuel is attached to each. On the other hand, in the exhaust pipe 16 of the engine, HC, CO,
A catalyst 17 such as a three-way catalyst for purifying NOx is provided.

The engine control circuit (hereinafter referred to as "ECU") 18 is mainly constituted by a microcomputer and executes a fuel injection program (not shown) stored in a built-in ROM (storage medium). Then, the ignition timing of the ignition plug 19 is controlled by controlling the fuel injection amount of the fuel injection valve 15 according to the engine operating state and executing an ignition control program (not shown).

By the way, at the time of cooling immediately after starting, the catalyst 1
7 is in an inactive state, it is not possible to sufficiently purify HC, CO, and NOx discharged from the engine 11. Therefore, the ECU 18 executes the catalyst early warm-up control program of FIG. 2 to retard the ignition timing to control the exhaust gas to a temperature at which the rich components (HC, CO) in the exhaust gas can be burned in the exhaust pipe 16. While increasing the temperature, as shown in FIG. 3, fuel injection to some of the cylinders of the engine 11 (for example, # 1 cylinder) is stopped, and the engine 11 is operated in the remaining cylinders (for example, # 2 to # 4 cylinders). Cylinder operation. As described above, by performing the ignition retard control and the reduced cylinder operation at the same time during the early catalyst warm-up control, the rich component in the high-temperature exhaust gas discharged from the operating cylinder is reduced to the unburned fuel discharged from the injection stop cylinder. After mixing with the oxygen of the air, afterburning naturally occurs in the exhaust pipe 16 on the upstream side of the catalyst 17, and the catalyst 17 is quickly warmed up by the combustion heat.

Hereinafter, the processing contents of the catalyst early warm-up control program of FIG. 2 for executing the catalyst early warm-up control will be described. This program is started, for example, at the same time when an ignition switch (not shown) is turned on, and plays a role as an exhaust gas temperature raising control means and a reduced cylinder operation control means described in the claims. When this program starts, first,
In step 101, it is determined whether or not the engine 11 is restarted in a high temperature state based on the cooling water temperature or the like. If the engine is restarted at a high temperature, the catalyst 17 is considered to be in an active state. Then, it is determined that the catalyst early warm-up control is not necessary, and this program is ended without performing the subsequent processing.

On the other hand, if it is determined that the engine is not restarted at a high temperature, that is, it is determined that the engine is in a cold start, the routine proceeds to step 102, where the engine is completed based on whether or not the engine speed NE exceeds a start determination value A (for example, 400 rpm) ( It is determined whether or not a complete explosion has occurred. Thereafter, when it is determined that the start is completed, the process proceeds to step 103, and the engine speed NE is set within a predetermined time after the start is completed.
Is greater than a first combustion determination value B (for example, 1400 rpm). If the engine speed NE does not exceed the first combustion determination value B within a predetermined time after the start is completed, it is considered that the combustion state is not stable. Therefore, the catalyst early warm-up control (ignition retard control, decrease It is determined that it is better not to perform the cylinder operation, and the program ends without performing the subsequent processing.

On the other hand, if the engine speed NE exceeds the first combustion determination value B within a predetermined time after the start is completed, it is determined that the combustion state is somewhat stable.
Proceeding to step 104, the ignition retard operation is started, and the ignition timing θ of the spark plug 19 is set to, for example, 0.01 ° C. A / 1 ms.
Retard at the rate of Then, in the next step 105, it is determined whether or not the combustion state is sufficiently stable depending on the increase in the engine speed NE immediately after the ignition retard operation is started. This determination is made based on whether or not the engine rotational speed NE has exceeded a second combustion determination value C (for example, 1500 rpm) slightly higher than the first combustion determination value B immediately after the start of the ignition retard operation.

As shown in FIG. 4, if the engine speed NE exceeds the second combustion determination value C immediately after the start of the ignition retarding operation, the combustion state is considered to be sufficiently stable. It is determined that there is no problem even if the reduced-cylinder operation is started immediately after the start of the retard operation, and the routine proceeds to step 106, where the reduced-cylinder operation is immediately started to stop the fuel injection to the injection stop cylinder.
During this reduced cylinder operation, the air-fuel ratio of the air-fuel mixture supplied to each operating cylinder is adjusted so that the HC amount in the exhaust gas of the operating cylinder does not become excessive with respect to the oxygen amount of the unburned air discharged from the injection stop cylinder. Control is performed near the stoichiometric air-fuel ratio or slightly to the lean side, and multiple ignitions for performing a plurality of ignitions during one combustion stroke of each operating cylinder are executed to stabilize the combustion state of the operating cylinder.

After the start of the reduced cylinder operation, the routine proceeds to step 107,
It is determined whether the ignition timing θ has been retarded to the target ignition timing θm. The target ignition timing θm is set to an ignition timing (for example, ATDC 10 ° C.) at which a rich component in the exhaust gas can be raised to a temperature at which the exhaust gas can be burned in the exhaust pipe 16. If the ignition timing θ has not been retarded to the target ignition timing θm, the temperature continues to be 0.01 ° C. A / 1
ms, the ignition timing is continued at a rate of ms. Thereafter, when the ignition timing θ is retarded to the target ignition timing θm, the routine proceeds to step 108, where the ignition timing θ is fixed to the target ignition timing θm, and the routine proceeds to step 112. Proceed to. With this ignition retard control,
The temperature of the exhaust gas discharged from the operating cylinder is raised to a high temperature and the catalyst 1
Afterburning occurs in the exhaust pipe 16 on the upstream side of 7, and the catalyst 17 is warmed up by the combustion heat.

On the other hand, if the combustion stability decreases immediately after the start of the ignition retard operation, the increase in the engine rotational speed NE slows down. Therefore, in step 105, the engine rotational speed NE immediately after the start of the ignition retard operation becomes the second combustion. It is determined that the value is equal to or less than the determination value C. In this case, since the combustion state immediately after the start of the ignition retarding operation is not sufficiently stable, the reduced-cylinder operation is not immediately started, and the ignition timing is retarded until the ignition timing θ is retarded to the target ignition timing θm. Continue only operation (Step 10
9). When the ignition timing θ is retarded to the target ignition timing θm, the ignition timing θ is fixed to the target ignition timing θm (step 110), and the reduced cylinder operation is started (step 1).
11). As a result, the unburned air discharged from the injection stop cylinder is mixed with the high-temperature exhaust gas to generate afterburning in the exhaust pipe 16 on the upstream side of the catalyst 17, and the catalyst 17 is warmed up by the combustion heat.

During the early catalyst warm-up control (reduced cylinder operation and ignition retard control) executed as described above, it is determined in step 112 whether the catalyst early warm-up control termination condition is satisfied. . The catalyst early warm-up control termination condition is, for example, one of the following conditions (1) to (5). A predetermined time T has elapsed since the start was completed. The automatic transmission was shifted from the N range to the D range. Racing (the accelerator pedal was depressed)

Here, the predetermined time T in the formula (1) is the catalyst 1
7 is set to a time sufficient to warm up to the activation temperature. Therefore, if the condition is satisfied, it can be determined that the warm-up of the catalyst 17 has been completed. In the cases of (1) and (2), the engine load increases, so that it is necessary to increase the combustion stability and the engine torque. Therefore, it is desirable to end the catalyst early warm-up control.

If none of the above is satisfied, the catalyst early warm-up control is continued. If any of the following is satisfied, it is determined that it is the end timing of the catalyst early warm-up control. Proceeding to 113, the catalyst early warm-up control (ignition retard control and reduced cylinder operation) is terminated, and this program is terminated.

According to the embodiment (1) described above,
During the early catalyst warm-up control, the ignition timing θ is set to the target ignition timing θm
The exhaust gas rich component of the exhaust gas is heated to a temperature at which the rich component of the exhaust gas can be burned in the exhaust pipe 16 and the reduced-cylinder operation is performed to stop the injection of the rich component in the high-temperature exhaust gas discharged from the operating cylinder. Afterburning is generated by mixing with unburned air discharged from the cylinder, and the catalyst 17 is warmed up by the combustion heat. As a result, after-burning can be generated and the catalyst 17 can be quickly warmed up without providing an ignition device for igniting the exhaust gas, thereby reducing the cost and improving the catalyst warm-up performance by simplifying the configuration and reducing the number of parts. And can be compatible.

Immediately after the start in which the catalyst early warm-up control is performed, the engine 11 is in the process of warming up, so that the HC amount in the exhaust gas tends to increase. Accordingly, if the supply air-fuel ratio of the operating cylinder is made rich during the catalyst early warm-up control, the amount of HC discharged from the operating cylinder becomes excessive with respect to the amount of oxygen of the unburned air discharged from the injection stop cylinder. Therefore, there is a possibility that the amount of HC discharged into the atmosphere may increase.

In this regard, in the present embodiment (1), the supply air-fuel ratio of the operating cylinder is controlled to be close to the stoichiometric air-fuel ratio or slightly lean during the reduced-cylinder operation. The amount of HC can be reduced to the minimum amount required for afterburning, and HC in exhaust gas can be sufficiently combusted with the oxygen of unburned air discharged from the injection stop cylinder. It is possible to reduce the amount of HC discharged into the atmosphere.

In this embodiment (1), multiple ignition is executed in the operating cylinder during the reduced cylinder operation.
While performing the ignition retard control, the combustion state of the operating cylinder can be stabilized by the multiple ignition, and there is an advantage that torque fluctuation and engine vibration during reduced cylinder operation can be suppressed. However, in the present invention, the multiple ignition may not be performed during the reduced-cylinder operation. Even in this case, the intended object of the present invention can be sufficiently achieved.

From the viewpoint of early warm-up of the catalyst, it is desirable to start the ignition retard control and the reduced cylinder operation as soon as possible. However, if the reduced cylinder operation is started at a time when the combustion state is not sufficiently stabilized, the torque is reduced. Fluctuation and engine vibration may increase.

In consideration of such circumstances, in this embodiment (1), the combustion state immediately after the start of the ignition retard operation is determined based on the increase in the engine speed NE immediately after the start of the ignition retard operation, and FIG. As shown in (2), when the engine speed NE exceeds the second combustion determination value C immediately after the ignition retarding operation is started and it can be determined that the combustion state is sufficiently stable, the engine speed NE decreases immediately after the ignition retarding operation is started. Start cylinder operation. Thus, it is possible to start the reduced-cylinder operation (catalyst warm-up due to afterburning) at an early stage while preventing the torque fluctuation due to the reduced-cylinder operation.

On the other hand, as shown in FIG. 5, when the engine speed NE immediately after the start of the ignition retard operation does not exceed the second combustion determination value C and it can be determined that the combustion state is not sufficiently stable, After the ignition retard operation is completed (that is, the combustion state is stabilized), the reduced cylinder operation is started. As a result, it is possible to reduce torque fluctuation and engine vibration caused by the reduced cylinder operation.

However, in the present invention, it is not always necessary to change the start timing of the reduced cylinder operation according to the operating state (combustion state), and the start timing of the reduced cylinder operation may be fixed. In this case, the ignition retard control may be started after the reduced cylinder operation is started, or the reduced cylinder operation may be started simultaneously with or after the start of the ignition retard control. As in the former case, if the reduced cylinder operation is started before the ignition retard control, the catalyst early warm-up control can be performed while reducing the HC amount in the exhaust gas by the reduced cylinder operation. HC emissions into the atmosphere can be reduced. On the other hand, if the reduced cylinder operation is started at the same time as or after the ignition retard control is started, as in the latter case, the start timing of the reduced cylinder operation can be delayed as compared with the former case. Can start reduced cylinder operation under stable combustion conditions,
It is possible to reduce torque fluctuation and engine vibration due to reduced cylinder operation.

In this embodiment (1), the injection stop cylinder is fixed to a specific cylinder (for example, # 1 cylinder) during the reduced cylinder operation. However, the injection stop cylinder is sequentially changed during the reduced cylinder operation. Is also good. For example, the injection stop cylinder may be sequentially changed every cycle from a plurality of specific cylinders, or the injection stop cylinder may be sequentially changed every cycle from all cylinders. In this way, the torque fluctuation due to the injection stop cylinder can be dispersed to make it difficult for the driver to feel, and without giving the driver discomfort,
Reduced cylinder operation can be performed. It goes without saying that the fuel injection of a plurality of cylinders may be stopped during the reduced cylinder operation.

[Embodiment (2)] In an embodiment (2) of the present invention shown in FIG. 6, an electromagnetic drive device (not shown) which is a variable valve timing means is provided to each cylinder of the engine 20. A drive-type exhaust valve (not shown) is provided, and the valve timing of the exhaust valve can be freely changed by controlling the electromagnetic drive device by the ECU 21. Further, during the reduced-cylinder operation, the ECU 21 combines the unburned air discharged from the injection stop cylinder (for example, the # 1 cylinder) with the high-temperature exhaust gas discharged from at least one operating cylinder at the junction of the exhaust manifold 22. Thus, the valve timing of the exhaust valve of the injection stop cylinder is adjusted. At this time, the exhaust valve of the injection stop cylinder is opened and closed a plurality of times in one cycle, so that the unburned air discharged from the injection stop cylinder and the high temperature exhaust gas discharged from the plurality of operation cylinders at the junction of the exhaust manifold 22 respectively. You may make it join. When the exhaust valve of the injection stop cylinder is opened and closed multiple times in one cycle, the intake air is opened twice in one cycle by opening the intake valve in the intake stroke and the combustion (expansion) stroke of the injection stop cylinder. You may inhale. Other configurations and controls are the same as those in the embodiment (1).

According to the embodiment (2) configured as described above, the unburned air from the injection stop cylinder and the high-temperature exhaust gas from the operating cylinder are surely merged at the junction of the exhaust manifold 22 so as to be sufficiently mixed. Since it is possible to mix, afterburning can be effectively promoted.

In this embodiment (2), an electromagnetically driven exhaust valve is used. However, in an engine provided with a cam driven exhaust valve, the phase of the camshaft with respect to the crankshaft is changed by oil pressure to exhaust. A hydraulically driven variable valve timing mechanism that changes the valve timing of the valve may be used.

[Embodiment (3)] Next, an embodiment (3) of the present invention will be described with reference to FIGS. In the present embodiment (3), for example, each cylinder of the five-cylinder engine 23 has:
An electromagnetically driven intake valve and an electromagnetically driven exhaust valve (both not shown) are provided, and the ECU 24 controls each electromagnetically driven device (not shown) to control the valve timing of the intake and exhaust valves. It has become.

The ECU 24 stops the fuel injection to the injection stop cylinder (for example, the # 5 cylinder) during the reduced cylinder operation, and sets the valve timing of the intake valve and the exhaust valve of the operating cylinder (for example, # 1 to 4 cylinders), the fuel The injection timing and the ignition timing are controlled at intervals of a crank angle (for example, 180 ° C) obtained by dividing 720 ° C by the number of operating cylinders (for example, 4). Other configurations and controls are the same as those in the embodiment (1).

In the embodiment (3) configured as described above, during the reduced cylinder operation, explosion (combustion) of each operating cylinder occurs at every fixed crank angle obtained by dividing 720 ° A by the number of operating cylinders. Therefore, it is possible to operate the engine 23 in a combustion cycle similar to that of an engine having the same number of operating cylinders as the number of operating cylinders, and it is possible to effectively reduce torque fluctuation and engine vibration due to reduced cylinder operation. it can.

In each of the embodiments described above, the present invention is applied
Although applied to a cylinder or five-cylinder engine, it can be widely applied to engines of other cylinder numbers.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an entire engine control system showing an embodiment (1) of the present invention.

FIG. 2 is a flowchart showing a processing flow of a catalyst early warm-up control program.

FIG. 3 is a diagram for explaining a combustion cycle and fuel injection timing during a reduced cylinder operation according to the embodiment (1).

FIG. 4 is a time chart showing an example of early catalyst warm-up control when the combustion state immediately after the start of the ignition retard operation is stable;

FIG. 5 is a time chart showing an example of early catalyst warm-up control when the combustion state immediately after the start of the ignition retard operation is not stable;

FIG. 6 is a schematic configuration diagram of an entire engine control system showing an embodiment (2) of the present invention.

FIG. 7 is a schematic configuration diagram of an entire engine control system showing an embodiment (3) of the present invention.

FIG. 8 is a diagram for explaining a combustion cycle and fuel injection timing during reduced cylinder operation according to the embodiment (3).

[Explanation of symbols]

11 ... engine (internal combustion engine), 15 ... fuel injection valve, 16
... exhaust pipe (exhaust gas passage), 17 ... catalyst, 18 ... ECU
(Exhaust gas temperature raising control means, reduced cylinder operation control means), 19: spark plug, 20: engine, 21: ECU, 22: exhaust manifold, 23: engine, 24: ECU.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 41/06 330 F02D 41/06 330Z 45/00 301 45/00 301D F-term (Reference) 3G084 BA09 BA13 BA16 BA17 BA23 CA02 DA00 DA10 EA11 EC01 EC02 EC03 FA33 3G091 AA02 AA17 AB01 BA03 BA13 CB02 CB05 CB06 DA02 DA07 DA08 FA04 FA05 3G092 AA01 BA05 BA08 BA09 BB01 CA07 DA01 DA02 DA08 EA01 EA04 EA06 EA00 FA01 FA01 FA00 LA07 MA01 MA11 MA24 NA08 NE12 NE19 PE01Z

Claims (9)

[Claims] 1. An early warm-up control device for early warming up a catalyst for purifying exhaust gas of an internal combustion engine, wherein a rich component in the exhaust gas is heated to an exhaust gas temperature at which a rich component in the exhaust gas can be combusted in an exhaust gas passage during early catalyst warm-up control. Exhaust gas temperature raising control means for performing ignition retard control so that fuel injection to some cylinders (hereinafter referred to as “injection stopped cylinders”) is stopped during early catalyst warm-up control and the remaining cylinders (hereinafter referred to as “operating cylinders”). ), The reduced-cylinder operation control means for performing the reduced-cylinder operation for operating the internal combustion engine. 2. The reduced-cylinder operation control means controls an air-fuel ratio of an air-fuel mixture supplied to the operating cylinder to a value close to a stoichiometric air-fuel ratio or slightly lean during a reduced-cylinder operation. An early warm-up control device for an exhaust gas purifying catalyst as described in the above. 3. The exhaust gas according to claim 1, wherein the reduced cylinder operation control means performs a plurality of ignitions during one combustion stroke of the operating cylinder during the reduced cylinder operation. Early warm-up control device for purification catalyst. 4. The exhaust gas temperature raising control means starts ignition retard control after starting the reduced cylinder operation by the reduced cylinder operation control means. Early warm-up control device for exhaust gas purifying catalyst. 5. The reduced-cylinder operation control means starts the reduced-cylinder operation simultaneously with or after starting the ignition retard control by the exhaust gas temperature raising control means.
4. The early warm-up control device for an exhaust gas purifying catalyst according to any one of claims 1 to 3. 6. The exhaust gas purifying catalyst according to claim 1, wherein the reduced-cylinder operation control means changes the start timing of the reduced-cylinder operation according to an operating state after the engine is started. Early warm-up control device. 7. The exhaust gas purifying catalyst according to claim 1, wherein the reduced cylinder operation control means sequentially changes the injection stop cylinder during the reduced cylinder operation. Control device. 8. A variable valve timing means for changing a valve timing of an exhaust valve of the internal combustion engine, wherein the reduced cylinder operation control means sets the valve timing of the exhaust valve of the injection stop cylinder to the operating cylinder during the reduced cylinder operation. The early warm-up control device for an exhaust gas purifying catalyst according to any one of claims 1 to 7, wherein the controller is changed according to the valve timing of the exhaust valve. 9. Variable valve timing means for changing valve timings of an intake valve and an exhaust valve of the internal combustion engine, wherein the reduced cylinder operation control means includes a valve for an intake valve and an exhaust valve of the operating cylinder during the reduced cylinder operation. The timing, fuel injection timing, and ignition timing are determined by the number of operating cylinders as 720.
9. The early warm-up control apparatus for an exhaust gas purifying catalyst according to claim 1, wherein the control is performed at a crank angle interval obtained by dividing the temperature (C).