阅读说明：本技术 内燃机的控制装置及控制方法 (Control device and control method for internal combustion engine ) 是由 野濑勇喜 池田悠人 正源寺良行 安藤广和 于 2019-08-02 设计创作，主要内容包括：提供一种内燃机的控制装置及控制方法。内燃机的控制装置构成为控制内燃机。内燃机具备缸内喷射阀、端口喷射阀、点火装置、排气通路及三元催化剂装置。控制装置具备燃料导入处理部。燃料导入处理部构成为,实施使导入到汽缸的燃料与空气的混合气不在该汽缸内燃烧而向排气通路导入的燃料导入处理。燃料导入处理部构成为,在仅缸内喷射阀及端口喷射阀中的端口喷射阀执行燃料喷射的状态下实施燃料导入处理。(A control device and a control method for an internal combustion engine are provided. The control device for an internal combustion engine is configured to control the internal combustion engine. An internal combustion engine is provided with an in-cylinder injection valve, a port injection valve, an ignition device, an exhaust passage, and a three-way catalyst device. The control device is provided with a fuel introduction processing part. The fuel introduction processing unit is configured to perform fuel introduction processing for introducing a mixture of fuel and air introduced into the cylinder into the exhaust passage without combusting the mixture in the cylinder. The fuel introduction processing unit is configured to perform the fuel introduction processing in a state where fuel injection is performed by only one of the in-cylinder injection valve and the port injection valve.)

1. A control device for an internal combustion engine, configured to control the internal combustion engine,

the internal combustion engine is provided with:

an in-cylinder injection valve for injecting fuel into the cylinder;

a port injection valve that injects fuel into the intake port;

an ignition device that ignites an air-fuel mixture introduced into the cylinder by a spark;

an exhaust passage through which gas discharged from the cylinder flows; and

a three-way catalyst device provided in the exhaust passage,

the control device includes a fuel introduction processing unit configured to perform a fuel introduction process of introducing a mixture of fuel and air introduced into the cylinder into the exhaust passage without combusting the mixture in the cylinder,

the fuel introduction processing unit is configured to perform the fuel introduction processing in a state where fuel injection is performed by only the port injection valve of the in-cylinder injection valve and the port injection valve.

2. The control apparatus of an internal combustion engine according to claim 1,

the control device is configured to execute the fuel introduction process when a condition that:

a fuel cut execution flag is set;

a temperature rise of the three-way catalyst device is being requested; and

burned gas is swept from within the exhaust passage.

3. A control method of an internal combustion engine is a control method of an internal combustion engine, in which,

the internal combustion engine is provided with:

an in-cylinder injection valve for injecting fuel into the cylinder;

a port injection valve that injects fuel into the intake port;

an ignition device that ignites an air-fuel mixture introduced into the cylinder by a spark;

an exhaust passage through which gas discharged from the cylinder flows; and

a three-way catalyst device provided in the exhaust passage,

the method includes performing a fuel introduction process of introducing a mixture of fuel and air introduced into the cylinder into the exhaust passage without combusting the mixture in the cylinder,

the fuel introduction process is performed in a state where fuel injection is performed by only the in-cylinder injection valve and the port injection valve of the port injection valves.

Technical Field

The present disclosure relates to a control device and a control method for an internal combustion engine provided with a three-way catalyst device in an exhaust passage.

Background

U.S. patent application publication No. 2014/0041362 describes an in-cylinder injection type internal combustion engine including a three-way catalyst device provided in an exhaust passage, a particulate trap provided in the exhaust passage downstream of the three-way catalyst device, and an in-cylinder injection valve for injecting fuel into a cylinder. In such an internal combustion engine, emission of the particles generated in the cylinder to the outside air can be suppressed by trapping the particles in the trap. Since the trapped particles gradually accumulate in the trap, if the accumulation is left alone, the trap may eventually clog due to the accumulated particles.

In contrast, the internal combustion engine performs a fuel introduction process for raising the temperature of the three-way catalyst device during the inertia running of the vehicle, thereby purifying the particles accumulated on the trap by combustion. In the fuel introduction process, fuel injection from the in-cylinder injection valve is performed in a state where the spark of the spark plug is stopped, so that the air-fuel mixture is introduced into the exhaust passage without being combusted in the cylinder. At this time, the unburned air-fuel mixture introduced into the exhaust passage flows into the three-way catalyst device and is combusted in the three-way catalyst device. When the temperature of the three-way catalyst device is increased by the heat generated by this combustion, the temperature of the gas flowing out of the three-way catalyst device and into the trap also increases. When the trap is heated by the heat of the high-temperature gas and the temperature of the trap rises to the ignition point of the particles, the particles accumulated in the trap are burned and purified.

Further, an internal combustion engine using a dual injection system as a fuel injection system is known. In the dual injection method, fuel injection is performed by two fuel injection valves, a port injection valve that injects fuel into an intake port, and an in-cylinder injection valve that injects fuel into a cylinder. In contrast, although the above-mentioned document discloses an embodiment of the fuel introduction process in the in-cylinder injection type internal combustion engine, no proposal has been made on a specific embodiment of the fuel introduction process in the dual injection type internal combustion engine.

Disclosure of Invention

The invention according to claim 1 provides a control device configured to control an internal combustion engine. An internal combustion engine is provided with: an in-cylinder injection valve for injecting fuel into the cylinder; a port injection valve that injects fuel into the intake port; an ignition device for igniting the mixture gas introduced into the cylinder by a spark; an exhaust passage through which gas discharged from the cylinder flows; and a three-way catalyst device provided in the exhaust passage, wherein the control device of the internal combustion engine includes a fuel introduction processing unit configured to perform a fuel introduction process of introducing a mixture of fuel and air introduced into the cylinder into the exhaust passage without combusting the mixture in the cylinder. The fuel introduction processing unit is configured to perform the fuel introduction processing in a state where fuel injection is performed by only one of the in-cylinder injection valve and the port injection valve.

When the unburned air-fuel mixture is introduced into the exhaust passage by the fuel introduction process, the unburned air-fuel mixture flows into the three-way catalyst device and is combusted in the three-way catalyst device. The heat generated by this combustion increases the temperature of the three-way catalyst device, i.e., the catalyst temperature. If the fuel injection amount at this time is too large, the catalyst temperature may rise excessively. Further, regarding the fuel injection amount (hereinafter, referred to as an appropriate injection amount) by which the catalyst temperature can be appropriately increased within a range in which the temperature does not excessively increase, the smaller the intake air amount, and the higher the engine speed, the smaller the intake air amount.

On the other hand, the fuel injection amount per injection from the fuel injection valve is a minimum amount, which is a lower limit. In the case where the above-described appropriate injection amount is smaller than the minimum injection amount, the rise in the catalyst temperature can no longer be kept within a moderate range. On the other hand, the in-cylinder injection valve has a high fuel injection pressure to inject fuel into the cylinder compressed by the receiving piston to a high pressure. The minimum injection quantity of the in-cylinder injection valve is larger than the minimum injection quantity of the port injection valve. Therefore, when the fuel injection during the fuel introduction process is performed by the in-cylinder injection valve, the appropriate injection quantity is likely to be smaller than the minimum injection quantity, as compared with the case where the fuel injection is performed by the port injection valve. In this regard, the fuel introduction processing portion in the control device of the internal combustion engine performs the fuel introduction processing in a state where only the port injection valve of the in-cylinder injection valve and the port injection valve performs fuel injection. Therefore, in the internal combustion engine provided with the two fuel injection valves, i.e., the port injection valve and the in-cylinder injection valve, the exhaust gas introduction process for introducing the air-fuel mixture into the exhaust passage without combusting the air-fuel mixture in the cylinder can be suitably performed.

Claim 2 provides a control method of controlling an internal combustion engine. The internal combustion engine is provided with: an in-cylinder injection valve for injecting fuel into the cylinder; a port injection valve that injects fuel into the intake port; an ignition device that ignites an air-fuel mixture introduced into the cylinder by a spark; an exhaust passage through which gas discharged from the cylinder flows; and a three-way catalyst device provided in the exhaust passage. The method includes a step of performing a fuel introduction process of introducing a mixture of fuel and air introduced into the cylinder into the exhaust passage without combusting the mixture in the cylinder. The fuel introduction process is performed in a state where fuel injection is performed by only the in-cylinder injection valve and the port injection valve of the port injection valves.

Drawings

Fig. 1 is a schematic diagram showing the configuration of an embodiment of a control device for an internal combustion engine.

Fig. 2 is a flowchart of a fuel introduction processing routine executed by a fuel introduction processing unit provided in the control device.

Fig. 3 is a time chart showing an embodiment of the fuel introduction processing section.

Detailed Description

An embodiment of a control device for an internal combustion engine will be described in detail below with reference to fig. 1 to 3.

As shown in fig. 1, the internal combustion engine 10 includes a cylinder block 13 having a cylinder 12 for housing a piston 11, and a cylinder head 14 fixed to the cylinder block 13. The piston 11 is connected to a crankshaft 16 via a connecting rod 15. The connecting rod 15 and the crankshaft 16 constitute a crankshaft mechanism that converts the reciprocating motion of the piston 11 in the cylinder 12 into the rotational motion of the crankshaft 16.

An intake passage 17, which is an introduction passage of air into the cylinder 12, and an exhaust passage 26, which is an exhaust passage of exhaust gas generated by combustion in the cylinder 12, are connected to the cylinder 12. The cylinder head 14 is formed with an intake port 20 serving as a connection portion to the cylinder 12 in the intake passage 17, and an exhaust port 27 serving as a connection portion to the cylinder 12 in the exhaust passage 26. Further, the cylinder head 14 is provided with an intake valve 21 as a valve that selectively opens and closes the cylinder 12 with respect to the intake port 20, and an exhaust valve 28 as a valve that selectively opens and closes the cylinder 12 with respect to the exhaust port 27. Further, a port injection valve 22 for injecting fuel into the intake port 20 and an in-cylinder injection valve 23 for injecting fuel into the cylinder 12 are provided in the cylinder head 14. The cylinder head 14 is provided with an ignition device 24 for igniting the air-fuel mixture introduced into the cylinder 12 by a spark.

An air flow meter 18 that detects the flow rate of air flowing through the intake passage 17 (intake air amount GA) is provided in the intake passage 17. A throttle valve 19 as a valve for adjusting the intake air amount GA is provided in the intake passage 17 at a position downstream of the airflow meter 18. On the other hand, the exhaust passage 26 is provided with a three-way catalyst device 29 that oxidizes CO and HC in the exhaust gas and reduces NOx. Further, a trap 30 for trapping particulates is provided downstream of the three-way catalyst device 29 in the exhaust passage 26. An air-fuel ratio sensor 31 that detects the oxygen concentration of the gas flowing through the exhaust passage 26, that is, the air-fuel ratio ABYF of the mixture is provided upstream of the three-way catalyst device 29 in the exhaust passage 26. Further, a catalyst-out-gas temperature sensor 32 that detects a catalyst out-gas temperature THC, which is the temperature of the gas flowing out of the three-way catalyst device 29, is provided in the exhaust passage 26 between the three-way catalyst device 29 and the trap 30.

The control device 33 of the internal combustion engine 10 is configured as a microcomputer including an arithmetic processing circuit that executes arithmetic processing for control and a memory that stores control programs and data. The control device 33 receives detection signals of the air flow meter 18, the air-fuel ratio sensor 31, and the catalyst exhaust gas temperature sensor 32. Further, to the control device 33, detection signals of a crank angle sensor 34 that detects a crank angle θ c that is a rotation angle of the crankshaft 16, a vehicle speed sensor 35 that detects a vehicle speed V that is a traveling speed of the vehicle, and an accelerator position sensor 37 that detects an accelerator opening ACC that is an operation amount of an accelerator pedal 36 are input. The control device 33 controls parameters such as the opening degree of the throttle valve 19, the fuel injection amounts and timings of the port injection valve 22 and the in-cylinder injection valve 23, and the timing of applying spark to the ignition device 24 (ignition timing) based on the detection results of the sensors 34 to 37, thereby controlling the operation state of the internal combustion engine 10 according to the traveling condition of the vehicle. Further, the control device 33 calculates the rotation speed of the internal combustion engine 10 (engine rotation speed NE) based on the detection result of the crank angle θ c.

The control device 33 during the combustion operation of the internal combustion engine 10 selects an injection mode from among the port injection mode, the in-cylinder injection mode, and the split injection mode in accordance with the operating conditions of the internal combustion engine 10 (parameters such as the engine speed NE and the intake air amount GA) and performs fuel injection control. The entire requested amount of fuel is injected by port injection valve 22 in the port injection mode, and the entire requested amount of fuel is injected by in-cylinder injection valve 23 in the in-cylinder injection mode. In the split injection mode, a part of the fuel of the requested quantity is injected from port injection valve 22, and the remaining fuel is injected from in-cylinder injection valve 23.

The control device 33 includes, as a processing circuit, a fuel introduction processing unit 33A, and the fuel introduction processing unit 33A performs fuel introduction processing for raising the temperature of the three-way catalyst device 29 provided in the exhaust passage 26. The fuel introduction processing unit 33A is configured to perform the fuel introduction processing by performing fuel injection in a state where the spark of the ignition device 24 is stopped. In the present embodiment, fuel introduction processing unit 33A performs fuel introduction processing for the purpose of preventing clogging of trap 30.

Fig. 2 is a flowchart showing a fuel introduction processing routine relating to the implementation of the fuel introduction processing. This routine is repeatedly executed by the fuel introduction processing unit 33A at predetermined control cycles during the start of the control device 33.

When the process of the present routine is started, first, in step S100, the fuel introduction processing portion 33A determines whether or not the execution flag of the fuel introduction process is in the on state. When the execution flag of the fuel introduction process is in the purge state (NO), the process of this routine is terminated in this manner. In the case where the implementation flag is in the set state (YES), the process proceeds to step S110. The execution flag of the fuel introduction process is a flag indicating that the execution condition of the fuel introduction process is satisfied in the on state, and is a flag indicating that the execution condition is not satisfied in the off state. In the present embodiment, the execution condition of the fuel introduction process is set so as to be satisfied when all of the following conditions (1) to (3) are satisfied.

(1) The fuel-cut execution flag is in the on state. The fuel-cut execution flag is a flag indicating that an execution condition for fuel-cut at the time of deceleration, which is a condition for stopping fuel injection and spark (ignition) of the internal combustion engine 10 during the inertia running of the vehicle, is satisfied. Specifically, the fuel-cut execution flag is set when the accelerator opening ACC is 0 and the vehicle speed V is a certain value or more. Then, the fuel cut execution flag is cleared when the accelerator pedal 36 is depressed after the flag is set and reacceleration of the vehicle is requested or when the vehicle speed V decreases to a predetermined recovery speed or less.

(2) Warming of the three-way catalyst device 29 is being requested. As described above, in the present embodiment, the fuel introduction process is performed for raising the temperature of three-way catalyst device 29 for the purpose of cleaning by combustion of particles accumulated on trap 30. Control device 33 estimates the amount of particles deposited on trap 30 based on the operating state of internal combustion engine 10. The control device 33 requests a temperature increase of the three-way catalyst device 29 when the estimated amount exceeds a certain value.

(3) The burned gas is swept out from the exhaust passage 26. Immediately after the combustion of the internal combustion engine 10 is stopped, burned gas remains in the exhaust passage 26. In the present embodiment, the fuel introduction process is started from a state in which the gas in the exhaust passage 26 is replaced with air from burned gas. Specifically, it is determined that the burned gas is purged based on a case where the fuel cut continues for a predetermined time or more during deceleration.

When the execution flag of the fuel introduction process is in the on state (S100: yes), so that the process proceeds to step S110, in this step S110, the port injection mode is set as the injection mode of the internal combustion engine 10. Then, in the next step S120, the required injection amount and the required injection timing of the port injection valve 22 are calculated.

When calculating the required injection amount of the port injection valve 22 at this time, the fuel introduction processing portion 33A first determines the catalyst fuel input amount, which is the amount of fuel per unit time that is input to the three-way catalyst device 29, based on the intake air amount GA. The three-way catalyst device 29 in the fuel introduction process receives heat generated by combustion of fuel in the interior of the three-way catalyst device 29, and takes away the heat from the passing gas. The larger the amount of catalyst fuel charged, the larger the amount of heat received by the three-way catalyst device 29 at that time, and the larger the flow rate of the gas passing through the three-way catalyst device 29, the larger the amount of heat removed. In the fuel introduction process in which combustion is not performed in the cylinder 12, the flow rate of GAs passing through the three-way catalyst device 29 is substantially equal to the intake air amount GA. Therefore, if the catalyst fuel input amount is the same, the catalyst temperature is more likely to rise when the intake air amount GA is small than when the intake air amount GA is large. In the present embodiment, the catalyst fuel charge amount is determined so that when the intake air amount GA is small, the amount becomes smaller than when the intake air amount GA is large. Next, the fuel introduction processing unit 33A calculates, as a value of the required injection amount, the injection amount of the port injection valve 22 per injection required for fuel injection by an amount corresponding to the catalyst fuel injection amount, based on the catalyst fuel injection amount and the engine speed NE. That is, the number of times of fuel injection per unit time of the internal combustion engine 10 is obtained from the engine speed NE, and the quotient obtained by dividing the catalyst fuel input amount by the number of times of injection is calculated as the value of the required injection amount.

The fuel introduction processing unit 33A sets the required injection timing of the port injection valve 22 as follows. When performing fuel injection of the port injection valve 22 in the port injection mode or the split injection mode in the combustion operation of the internal combustion engine 10, the control device 33 sets the injection timing of the port injection valve 22 such that fuel injection is started before the intake valve 21 is opened. Further, this can extend the time from the injection to the combustion in the cylinder 12, thereby promoting the vaporization of the injected fuel. In contrast, the fuel introduction processing portion 33A sets the injection timing of the port injection valve 22 in the fuel introduction processing so that the fuel injection is started after the intake valve 21 is opened. This is for the following reason. In the fuel introduction process, the fuel may be vaporized before flowing into the three-way catalyst device 29 without performing combustion in the cylinder 12. On the other hand, a part of the fuel injected from the port injection valve 22 adheres to the wall surface of the intake port 20 and the intake valve 21. The amount of such fuel deposited is reduced in the case where fuel injection is performed while intake air is flowing in the intake port 20, as compared to the case where fuel injection is performed while the flow of intake air in the intake port 20 is stagnant during the closing of the intake valve 21. Therefore, in the present embodiment, the fuel adhesion can be suppressed by setting the timing at which the air flow flowing into the cylinder 12 from the intake port 20 after the intake valve 21 is opened becomes strong as the required injection timing.

Next, in step S130, the fuel introduction processing portion 33A determines whether or not the required injection amount is equal to or larger than the minimum injection amount of the port injection valve 22. When the required injection amount is equal to or larger than the minimum injection amount (yes in S130), the fuel injection to the port injection valve 22 is instructed based on the calculation result of the required injection amount and the required injection timing in step S140, and then the process of the present routine this time is ended. On the other hand, when the required injection amount is smaller than the minimum injection amount of the port injection valve 22 (no in S130), the fuel introduction processing portion 33A does not instruct fuel injection, that is, does not perform fuel injection, and ends the processing of the present routine this time.

Incidentally, when the fuel cut execution flag is in the on state but the execution flag of the fuel introduction process is in the off state, the control device 33 executes the fuel cut at the time of deceleration of the internal combustion engine 10. That is, at this time, control device 33 stops fuel injection from both port injection valve 22 and in-cylinder injection valve 23, and stops spark from ignition device 24. Thus, either of the deceleration-time fuel cut and the fuel introduction process is performed when the fuel cut execution flag is in the on state, and the combustion operation of the internal combustion engine 10 is stopped in either case.

The operation and effect of the present embodiment will be described.

Fig. 3 shows an example of an embodiment of the fuel introduction processing in the present embodiment. In fig. 3, the fuel cut execution flag is in the on state during the period from time t1 to time t3, and the combustion operation of the internal combustion engine 10 is stopped during this period. Incidentally, in the example of the figure, the combustion operation of the internal combustion engine 10 during the period before the time t1 and during the period after the time t3 is performed in the in-cylinder injection mode.

When the fuel-cut execution flag is set at time t1, the spark of the ignition device 24 and the fuel injection from the port injection valve 22 and the in-cylinder injection valve 23 are stopped, and deceleration-time fuel-cut of the internal combustion engine 10 is started. Then, at time t2 when scavenging of the exhaust passage 26 is completed, a flag for execution of the fuel introduction process is set.

When the execution flag of the fuel introduction process is set at time t2, fuel injection from the port injection valve 22 is started. On the other hand, at this time, the spark of the ignition device 24 is kept stopped. Therefore, the fuel injected by the port injection valve 22 at this time is not combusted in the cylinder 12 and is discharged to the exhaust passage 26 in an unburned state. That is, the air-fuel mixture of the fuel and the air introduced into the cylinder 12 is introduced into the exhaust passage 26 in an unburned state without being combusted in the cylinder 12. The unburned air-fuel mixture introduced into the exhaust passage 26 flows into the three-way catalyst device 29 and is combusted in the three-way catalyst device 29. The temperature of the three-way catalyst device 29 (hereinafter referred to as catalyst temperature) is increased by the heat generated by this combustion. When the catalyst temperature increases, the temperature of the gas flowing out of three-way catalyst device 29 and flowing into trap 30 also increases, and the temperature of trap 30 also increases upon receiving the heat of the gas. Accordingly, when the temperature of catcher 30 becomes equal to or higher than the ignition point of the particles, the particles accumulated in catcher 30 are burned and cleaned.

When the fuel cut execution flag is cleared at time t3, the execution flag of the fuel introduction process is also cleared. At time t3, the spark of ignition device 24 is restarted, fuel injection from in-cylinder injection valve 23 is started, and the combustion operation of internal combustion engine 10 is restarted in the in-cylinder injection mode.

As described above, the fuel introduction processing portion 33A in the present embodiment performs fuel injection in the fuel introduction processing by the port injection valve 22. That is, the fuel introduction processing portion 33A performs the fuel introduction processing in a state where fuel injection is performed by only the port injection valve 22 of the in-cylinder injection valve 23 and the port injection valve 22.

If an excessively large amount of fuel is charged into the three-way catalyst device 29 in the fuel introduction process, the catalyst temperature may excessively rise. On the other hand, since the port injection valve 22 cannot make the fuel injection amount per injection smaller than the minimum injection amount, if the fuel injection from the port injection valve 22 is performed when the required injection amount is smaller than the minimum injection amount, an excessively large amount of fuel is injected into the three-way catalyst device 29. In the present embodiment, when the required injection amount is smaller than the minimum injection amount of the port injection valve 22 (S130: no), fuel injection is not performed. In this case, the temperature rise of the three-way catalyst device 29 by the fuel introduction process may be stagnated while the operating state of the internal combustion engine 10 (the engine speed NE, the intake air amount GA) is in a state in which the required injection amount is smaller than the minimum injection amount of the port injection valve 22.

Here, it is considered that fuel injection in the fuel introduction process is carried out by in-cylinder injection valve 23 instead of port injection valve 22. In-cylinder injection valve 23 needs to inject fuel into cylinder 12 that receives compression by piston 11 and has a high pressure, so the injection pressure of the fuel by in-cylinder injection valve 23 is set to be significantly higher than the pressure of port injection valve 22. On the other hand, there is a time (minimum injection time) that becomes the lower limit for both the port injection valve 22 and the in-cylinder injection valve 23, of the time required for one injection. The higher the injection pressure is, the more the amount of fuel injected by fuel injection (minimum injection amount) in the minimum injection time is. It is technically difficult to set the minimum injection time of in-cylinder injection valve 23 to a time significantly shorter than the minimum injection time of port injection valve 22, so the minimum injection quantity of in-cylinder injection valve 23 is larger than the minimum injection quantity of port injection valve 22. Thus, when the fuel injection during the fuel introduction process is performed by in-cylinder injection valve 23, the opportunity for the situation in which the fuel injection is stopped is increased by requiring the injection quantity to be smaller than the minimum injection quantity, as compared with the case of performing the fuel injection by port injection valve 22. Thus, it is advantageous in that the three-way catalyst device 29 can be heated by the fuel introduction process more frequently in the case of using the port injection valve 22 than in the case of using the in-cylinder injection valve 23.

When in-cylinder injection valve 23 injects the fuel, the fuel adheres to the injection port of in-cylinder injection valve 23 and the periphery thereof. In the fuel introduction process in which combustion in cylinder 12 is not performed, the temperature in cylinder 12 is low, and vaporization of the fuel adhering to the injection port of in-cylinder injection valve 23 and its periphery is less likely to progress. Therefore, when fuel injection is performed during the fuel introduction process using in-cylinder injection valve 23, the combustion operation of internal combustion engine 10 may be restarted with a large amount of fuel adhering to the injection port and its surroundings. Then, the adhered fuel deposited by exposure to the heat of combustion in cylinder 12 may clog the injection port of in-cylinder injection valve 23. Accordingly, it is advantageous in that the accumulation of deposits at the injection port of in-cylinder injection valve 23 can be suppressed even in the case where the fuel injection during the fuel introduction process is performed by port injection valve 22, as compared with the case where the fuel injection during the fuel introduction process is performed by in-cylinder injection valve 23.

This embodiment can be modified and implemented as follows. This embodiment and the following modifications can be combined and implemented within a range not technically contradictory to the technology.

In the above embodiment, the unburned air-fuel mixture is introduced into the exhaust passage 26 by fuel injection with the spark of the ignition device 24 stopped. Further, the timing at which the mixture in the cylinder 12 can be ignited by the spark of the ignition device 24 is limited to a period in the vicinity of compression top dead center. That is, there is a period during which the mixture in the cylinder 12 does not burn even if the spark is performed. Accordingly, by performing the fuel injection while the spark of the ignition device 24 is performed in such a period, the fuel introducing process of introducing the unburned air-fuel mixture into the exhaust passage 26 can be performed.

In the above embodiment, the fuel introduction process is performed for the purpose of cleaning by combustion of the particles accumulated in trap 30, but the fuel introduction process may be performed for the purpose of raising the temperature of three-way catalyst device 29 for other purposes. For example, when the catalyst temperature decreases and the exhaust gas purification ability of the three-way catalyst device 29 decreases, it is conceivable to perform catalyst temperature increase control in order to recover the exhaust gas purification ability.

In the above embodiment, the fuel introduction process is performed when the execution condition of the fuel cut is satisfied during deceleration in the inertia running of the vehicle, but the fuel introduction process may be performed in a condition other than the inertia running of the vehicle as long as the rotation of the crankshaft 16 can be maintained in a state in which the combustion of the internal combustion engine 10 is stopped. Some hybrid vehicles that are equipped with a motor as a drive source in addition to an internal combustion engine are capable of rotating a crankshaft by using power of the motor in a state where a combustion operation of the internal combustion engine is stopped. In such a hybrid vehicle, the fuel introduction process can be performed while rotating the crankshaft by the power of the motor.

The control device 33 or the fuel introduction processing unit 33A is not limited to a configuration including a CPU and a memory and executing software processing. For example, a dedicated hardware circuit (e.g., ASIC) may be provided for performing hardware processing on at least a part of the processing performed by software processing in each of the above embodiments. That is, the control device or the fuel introduction processing portion 33A may be configured as any one of the following (a) to (c). (a) The apparatus includes a processing device for executing all of the above-described processing in accordance with a program, and a program storage device such as a ROM for storing the program. (b) The apparatus includes a processing device and a program storage device for executing a part of the above-described processing in accordance with a program, and a dedicated hardware circuit for executing the remaining processing. (c) The apparatus includes a dedicated hardware circuit for executing all of the above-described processing. Here, a plurality of software processing circuits and dedicated hardware circuits may be provided, each of which includes a processing device and a program storage device. That is, the above-described processing may be executed by a processing circuit including at least one of one or more software processing circuits and one or more dedicated hardware circuits.