CN111980822B

CN111980822B - Control device and method for hybrid vehicle

Info

Publication number: CN111980822B
Application number: CN202010429078.0A
Authority: CN
Inventors: 安藤大吾
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 2019-05-22
Filing date: 2020-05-20
Publication date: 2022-12-20
Anticipated expiration: 2040-05-20
Also published as: JP2020189569A; JP7211264B2; CN111980822A

Abstract

A control device and a method for a hybrid vehicle are provided, the control device being applied to a hybrid vehicle provided with an internal combustion engine, a 1 st motor generator, and a power distribution and integration mechanism. The control device is provided with: a combustion determination unit that determines whether or not an air-fuel mixture is being stably combusted in a cylinder of an internal combustion engine; and a motor control unit for controlling the 1 st motor generator. The motor control unit executes a depression process for outputting a 1 st motor torque from the 1 st motor/generator when the cylinder air-fuel mixture is being stably combusted, and does not execute the depression process when the cylinder air-fuel mixture is not being stably combusted.

Description

Control device and method for hybrid vehicle

Technical Field

The invention relates to a control device and a control method for a hybrid vehicle.

Background

Japanese patent application laid-open publication No. 2011-24586 discloses a hybrid vehicle including an internal combustion engine, a motor generator, and a power split mechanism. The power distributing mechanism has a plurality of gears that mesh with each other. Of the plurality of gears, the 1 st gear is coupled to the internal combustion engine, and the 2 nd gear is coupled to the motor generator. In the hybrid vehicle, a step-down process is performed to output a torque in a direction to increase a load applied to the internal combustion engine from the motor generator in order to suppress rattling between the gears that mesh with each other (japanese character "" たつき).

When the depression processing is executed, the load applied to the internal combustion engine becomes large. Therefore, when combustion of an air-fuel mixture in a cylinder of the internal combustion engine becomes unstable during execution of the push-down process, there is a possibility that misfire (misfiring) in the internal combustion engine occurs.

Disclosure of Invention

In order to solve the above problem, according to a first aspect of the present invention, a control device for a hybrid vehicle is provided. The hybrid vehicle includes an internal combustion engine, a motor generator, and a power split mechanism having a plurality of gears that mesh with each other. The hybrid vehicle is configured to generate electric power by inputting an output torque of the internal combustion engine to the motor generator via the power split device. The control device is provided with: a combustion determination unit configured to determine whether or not an air-fuel mixture is being stably combusted in a cylinder of an internal combustion engine when the internal combustion engine is operated; and a motor control unit configured to control the motor generator. The motor control unit is configured to execute a depression process of outputting a torque in a direction in which a load applied to the internal combustion engine is increased from the motor generator when it is determined that the air-fuel mixture is being stably combusted in the cylinder, and not execute the depression process when it is not determined that the air-fuel mixture is being stably combusted in the cylinder.

In order to solve the above problem, according to a second aspect of the present invention, a control device for a hybrid vehicle is provided. The hybrid vehicle includes an internal combustion engine and a motor generator as power sources of the vehicle. The internal combustion engine is provided with: an EGR device that recirculates exhaust gas discharged from the inside of the cylinder to the exhaust passage to the intake passage as EGR gas; a catalyst provided in the exhaust passage; and an EGR valve provided in the EGR device and configured to adjust an amount of EGR gas recirculated to the intake passage. The control device is provided with: a normal processing unit configured to adjust an opening degree of a throttle valve provided in the intake passage and an opening degree of the EGR valve in accordance with a change in the required engine output when a decrease amount of the required engine output that is a required output to the engine is smaller than a determination decrease amount; and a sudden-decrease processing unit configured to execute a sudden-decrease process of decreasing the opening degree of the throttle valve and the opening degree of the EGR valve so that a decrease speed of the opening degree of the EGR valve is higher than a decrease speed of the opening degree of the throttle valve, when an amount of decrease in the required engine output is equal to or larger than the determination decrease amount.

In order to solve the above problem, according to a third aspect of the present invention, a control method for a hybrid vehicle is provided. The hybrid vehicle includes an internal combustion engine, a motor generator, and a power split mechanism having a plurality of gears that mesh with each other. The hybrid vehicle is configured to generate electric power by inputting an output torque of the internal combustion engine to the motor generator via the power split device. The control method comprises the following steps: determining whether or not an air-fuel mixture is being stably combusted in a cylinder of an internal combustion engine while the internal combustion engine is operating; and executing a depression process when it is determined that the air-fuel mixture is being stably combusted in the cylinder, the depression process being a process of causing the motor generator to output a torque in a direction in which a load applied to the internal combustion engine becomes larger, the depression process not being executed when it is not determined that the air-fuel mixture is being stably combusted in the cylinder.

Drawings

Fig. 1 is a schematic diagram showing a general configuration of a control device for a hybrid vehicle and a hybrid vehicle including the control device according to embodiment 1.

Fig. 2 is a schematic diagram showing a schematic configuration of an internal combustion engine provided in the hybrid vehicle.

Fig. 3 is a flowchart illustrating a processing routine executed by the combustion determination unit of the control device.

Fig. 4 is a flowchart illustrating a processing routine executed by the motor control unit of the control device.

Fig. 5 is a flowchart illustrating a processing routine executed by the emergency drop processing unit of the control device.

Fig. 6 is a flowchart for explaining a processing routine executed by the ignition timing adjusting portion of the control device.

Fig. 7 is a flowchart illustrating a processing routine executed by the injection valve control section of the control device.

Fig. 8 is a flowchart illustrating a processing routine executed by the injection valve control unit of the control device according to embodiment 2.

Detailed Description

(embodiment 1)

Hereinafter, a control device for a hybrid vehicle according to embodiment 1 will be described with reference to fig. 1 to 7.

Fig. 1 shows a general configuration of a hybrid vehicle to which a control device 100 according to embodiment 1 is applied. The hybrid vehicle includes an internal combustion engine 10 as one of power sources of the vehicle, a power distribution/integration mechanism 40 connected to a crankshaft 18 of the internal combustion engine 10, and a 1 st motor/generator 71 connected to the power distribution/integration mechanism 40. The power distribution integration mechanism 40 is an example of a "power distribution mechanism". The power distribution/integration mechanism 40 is coupled to the 2 nd motor generator 72 via the reduction gear 50, and is coupled to the drive wheels 62 via the reduction mechanism 60 and the differential 61.

The power distribution and integration mechanism 40 is a planetary gear mechanism, and includes a sun gear 41 that is an external gear, and a ring gear 42 that is an internal gear disposed coaxially with the sun gear 41. A plurality of pinion gears 43 that mesh with both the sun gear 41 and the ring gear 42 are disposed between the sun gear 41 and the ring gear 42. Each pinion gear 43 is supported by the carrier 44 in a state of freely rotating and revolving. The sun gear 41 is coupled to the 1 st motor/generator 71. Carrier 44 is coupled to crankshaft 18. The ring gear 42 is connected to a ring gear shaft 45. The ring gear shaft 45 is connected to both the reduction gear 50 and the reduction mechanism 60.

When the output torque of the internal combustion engine 10 is input to the carrier 44, the output torque is distributed to the sun gear 41 and the ring gear 42. That is, the 1 st motor generator 71 can generate electric power by inputting the output torque of the internal combustion engine 10 to the 1 st motor generator 71.

On the other hand, when the 1 st motor generator 71 is caused to function as a motor, the output torque of the 1 st motor generator 71 is input to the sun gear 41. Then, the output torque of the 1 st motor/generator 71 input to the sun gear 41 is distributed to the carrier 44 and the ring gear 42. The output torque of the 1 st motor/generator 71 is input to the crankshaft 18 via the carrier 44, whereby the crankshaft 18 can be rotated.

The reduction gear 50 is a planetary gear mechanism, and has a sun gear 51 as an external gear coupled to the 2 nd motor generator 72, and a ring gear 52 as an internal gear disposed coaxially with the sun gear 51. A ring gear shaft 45 is connected to the ring gear 52. A plurality of pinion gears 53 that mesh with both the sun gear 51 and the ring gear 52 are disposed between the sun gear 51 and the ring gear 52. Each pinion 53 is capable of rotating freely but not capable of revolving.

When decelerating the vehicle, the 2 nd motor generator 72 functions as a generator, whereby the vehicle can generate a regenerative braking force corresponding to the amount of power generated by the 2 nd motor generator 72. When the 2 nd motor generator 72 is caused to function as a motor, the output torque of the 2 nd motor generator 72 is input to the drive wheels 62 via the reduction gear 50, the ring gear shaft 45, the reduction mechanism 60, and the differential 61. This enables the drive wheel 62 to rotate. That is, the 2 nd motor generator 72 can also function as a power source of the vehicle.

The 1 st motor generator 71 exchanges electric power with the battery 77 via the 1 st inverter 75. The 2 nd motor generator 72 exchanges electric power with the battery 77 via the 2 nd inverter 76.

As shown in fig. 2, the internal combustion engine 10 has a plurality of cylinders 11. The intake air is introduced into each cylinder 11 through an intake passage 12. A throttle valve 13 is provided in the intake passage 12. A plurality of portions of the intake passage 12 on the downstream side of the throttle valve 13 are branched. A passage portion of the intake passage 12 that branches off for each cylinder 11 is referred to as "a branch passage portion 12A".

In each cylinder 11, the air-fuel mixture is combusted by spark discharge from an ignition device 14. The air-fuel mixture includes intake air introduced through the intake passage 12 and fuel injected from the fuel injection valve 15. The exhaust gas generated in each cylinder 11 by the combustion of the air-fuel mixture is discharged to the exhaust passage 16. A three-way catalyst 17, which is an example of a catalyst having a function of purifying exhaust gas, is provided in the exhaust passage 16.

The internal combustion engine 10 includes an EGR device 20, and the EGR device 20 recirculates a part of the exhaust gas flowing through the exhaust passage 16 to the intake passage 12 as EGR gas. The EGR device 20 includes an EGR passage 21 connected to a portion of the exhaust passage 16 downstream of the three-way catalyst 17, and an EGR valve 22 provided in the EGR passage 21. The EGR passage 21 is provided with a plurality of EGR ports 211 connected to the respective branch passage portions 12A. Therefore, when the EGR valve 22 is opened, the EGR gas flows back to the branch passage portion 12A via the EGR port 211. At this time, the larger the opening degree of the EGR valve 22, the larger the amount of EGR gas that flows back to the branch passage portion 12A. On the other hand, when the EGR valve 22 is closed, the backflow of EGR gas to the branch passage portion 12A is stopped.

Next, the control device 100 will be described with reference to fig. 1.

Detection signals are input to the control device 100 from various sensors. Examples of the sensors include a vehicle speed sensor 91, an air flow meter 92, a crank angle sensor 93, an air-fuel ratio sensor 94, and a water temperature sensor 95. The vehicle speed sensor 91 detects a vehicle speed VS and outputs a signal corresponding to the vehicle speed VS as a detection signal. The airflow meter 92 detects an intake air amount GA, which is an amount of intake air flowing through the intake passage 12, and outputs a signal corresponding to the intake air amount GA as a detection signal. The crank angle sensor 93 outputs a signal corresponding to the engine speed NE, which is the rotational speed of the crankshaft 18, as a detection signal. The air-fuel ratio sensor 94 detects the air-fuel ratio AF, and outputs a signal corresponding to the air-fuel ratio AF as a detection signal. The water temperature sensor 95 detects a water temperature TWT, which is the temperature of the cooling water circulating through the internal combustion engine 10, and outputs a signal corresponding to the water temperature TWT as a detection signal. The control device 100 controls the internal combustion engine 10 and the motor generators 71 and 72 based on detection signals from the various sensors 91 to 95.

The control device 100 includes a motor control unit 110, a battery monitoring unit 120, and an internal combustion engine control unit 130. The battery monitoring unit 120 monitors the state of the battery 77. For example, the battery monitoring unit 120 monitors the charge amount SOC of the battery 77 and the temperature TBT of the battery 77 as the state of the battery 77.

The engine control unit 130 includes, as functional units for controlling the internal combustion engine 10, a combustion determination unit 131, a normal processing unit 132, a rapid-decrease processing unit 133, a protection setting unit 134, an ignition timing adjustment unit 135, an injection valve control unit 136, and a blocking diagnosis unit 137.

The combustion determination unit 131 determines whether or not the air-fuel mixture is being stably combusted in the cylinder 11 of the internal combustion engine 10 during the engine operation. The specific contents of the determination process of whether or not the air-fuel mixture is stably combusted will be described later.

The normal processing unit 132 executes normal processing for adjusting the throttle opening SL, which is the opening of the throttle valve 13, and the EGR opening regrr, which is the opening of the EGR valve 22, during engine operation. In embodiment 1, the normal processing unit 132 executes the normal processing when the emergency lowering processing described later is not executed. In the normal processing, the normal processing unit 132 adjusts the throttle valve opening SL and the EGR opening regrr in accordance with the required engine output PEQ, which is the required output of the internal combustion engine 10. For example, in the normal processing, the normal processing unit 132 increases the throttle valve opening degree SL and the EGR opening degree regrr as the required engine output PEQ increases.

The rapid decrease processing unit 133 starts the rapid decrease processing on condition that a start condition of the rapid decrease processing is satisfied when the engine output PEQ is requested to decrease, the rapid decrease processing being processing for decreasing the throttle valve opening degree SL and the EGR valve opening degree regrr so that a decrease speed of the EGR valve opening degree regrr becomes higher than a decrease speed of the throttle valve opening degree SL. The contents of the conditions for starting the rapid-fall processing and the contents of the rapid-fall processing will be described later.

When the condition for starting the rapid decrease process is not satisfied even when the engine output PEQ is required to be decreased, the normal process by the normal processing unit 132 is executed to adjust the throttle valve opening SL and the EGR opening REGR.

The protection setting unit 134 sets a lower limit protection PELm of the engine output PE, which is the output of the internal combustion engine 10. The lower limit guard PELm is used when performing the emergency lowering processing. That is, during execution of the racing reduction process, the engine output PE does not fall below the lower limit guard PELm.

The protection setting unit 134 sets a value corresponding to the EGR rate Y as the lower limit protection PELm. The EGR rate Y is a value obtained by dividing the amount of EGR GAs recirculated to the intake passage 12 by the EGR device 20 by the intake air amount GA. The higher the EGR rate Y is, the smaller the proportion of the intake air in the gas introduced into the cylinder 11 is. Therefore, if the lower limit guard PELm is made smaller in spite of the high EGR rate Y, the amount of intake air introduced into the cylinder 11 may be too small, and misfires may occur in the internal combustion engine 10. Therefore, in embodiment 1, the protection setting unit 134 sets the lower limit protection PELm such that the higher the EGR rate Y, the larger the lower limit protection PELm.

The ignition timing adjustment unit 135 adjusts the ignition timing TINJ. In embodiment 1, the ignition timing adjusting section 135 may execute the ignition timing retarding process when the rapid decrease process is executed. The ignition timing retard process is a process of suppressing an increase in the engine output PE by retarding the ignition timing TINJ from the time when the ignition timing retard process is not executed. The conditions for executing the ignition timing retard process and the details of the ignition timing retard process will be described later.

The injection valve control unit 136 controls each fuel injection valve 15. In embodiment 1, when the rapid-decrease process is executed, the injection valve control unit 136 may execute a fuel cut process for stopping the fuel injection from each fuel injection valve 15. The starting condition and the ending condition of the fuel cut processing will be described later.

The blockage diagnosis unit 137 diagnoses whether or not there is a blocked EGR port 211 among the plurality of EGR ports connected to the EGR passage 21. When all the EGR ports 211 are not closed in a state where the EGR valve 22 is open, the amount of EGR gas introduced into each cylinder 11 is substantially the same. That is, the difference in the EGR rate Y for each cylinder 11 is small.

On the other hand, when only a part of the EGR port 211 is closed, the EGR gas is hardly introduced into the cylinder 11 corresponding to the closed EGR port 211. Further, the EGR gas is introduced into the cylinder 11 corresponding to the remaining EGR port 211. That is, the cylinders 11 with a low EGR rate Y and the cylinders 11 with a high EGR rate Y are present among the plurality of cylinders 11. Therefore, when the required engine output PEQ is maintained at a constant value, the amount of variation in the engine speed NE tends to be larger than in the case where the EGR port 211 is not closed.

Therefore, in embodiment 1, the blockage diagnosis unit 137 diagnoses whether or not there is a blocked EGR port 211 by comparing the variation in the engine speed NE when the EGR valve 22 is closed with the variation in the engine speed NE when the EGR valve 22 is open. For example, when the deviation between the variation in the engine speed NE when the EGR valve 22 is closed and the variation in the engine speed NE when the EGR valve 22 is open is small, the blockage diagnosis unit 137 diagnoses that there is no blocked EGR port 211. On the other hand, when the variation in the engine speed NE when the EGR valve 22 is closed and the variation in the engine speed NE when the EGR valve 22 is open are largely different from each other, the blockage diagnosis unit 137 diagnoses that there is a blocked EGR port 211.

The motor control unit 110 controls the 1 st inverter 75 to drive the 1 st motor generator 71. The motor control unit 110 controls the 2 nd inverter 76 to drive the 2 nd motor generator 72.

In embodiment 1, when the rapid-decrease process is executed, the motor control unit 110 may execute a power generation process for generating the 1 st motor generator 71. In addition, the motor control unit 110 may execute the push-down process or the push-up process when the rapid-decrease process is not executed even during the engine operation. The depression processing is processing for outputting a 1 st motor torque TQM1 from the 1 st motor generator 71, the 1 st motor torque TQM1 being a torque in a direction in which a load applied to the internal combustion engine 10 is increased. The push-up processing is processing for outputting a 2 nd motor torque TQM2 from the 1 st motor generator 71, and the 2 nd motor torque TQM2 is torque in a direction opposite to the direction of the 1 st motor torque TQM1. The details of the motor control unit 110 will be described later.

Next, a processing routine executed by the combustion determination unit 131 will be described with reference to fig. 3. The present processing routine is a routine for determining whether the air-fuel mixture is being stably combusted in the cylinder 11. The present processing routine is repeatedly executed without executing the fuel cut processing during the operation of the internal combustion engine.

In the present processing routine, in the first step S11, a determination is made as to whether or not the engine speed NE is equal to or greater than the determination engine speed NETh. The engine speed at which the required engine output PEQ is equal to or less than the predetermined value is set as the determination engine speed NETh. That is, the engine speed NE is normally not less than the determination engine speed NETh in a situation where the fuel cut-off process is not being executed during the execution of the engine operation. In other words, in the case where the engine speed NE is less than the determination engine speed NETh, there is a possibility that the air-fuel mixture is not stably combusted in the cylinder 11. If the engine speed NE is less than the determination engine speed NETh in step S11 (NO), the process proceeds to step S17, which will be described later. On the other hand, when the engine speed NE is equal to or higher than the determination engine speed NETh (YES in S11), the process proceeds to the next step S12.

In step S12, it is determined whether or not the water temperature TWT is equal to or higher than the determination water temperature TWTTh. The determination water temperature TWTTh is set as a determination criterion for whether the warm-up operation of the internal combustion engine 10 is completed. If the warm-up operation is not completed, the mixture may not be stably combusted in the cylinder 11. If the water temperature TWT is lower than the determination water temperature TWTTh in step S12 (no), it can be determined that the warm-up operation is not completed, and the process proceeds to step S17. On the other hand, when the water temperature TWT is equal to or higher than the determination water temperature TWTTh (S12: YES), the process proceeds to the next step S13.

In step S13, it is determined whether or not the engine start is completed. For example, when the internal combustion engine 10 has completed an explosion, it is determined that the engine start is completed. When the engine start is not completed, the mixture may not be stably combusted in the cylinder 11. If the engine start is not completed in step S13 (no), the process proceeds to step S17. On the other hand, when the engine start is completed (yes in S13), the process proceeds to the next step S14.

In step S14, it is determined whether or not the fuel injected from the fuel injection valve 15 is fuel having high combustibility. During engine operation, the fuel injection amount is determined based on a base injection amount corresponding to the required engine output PEQ and a feedback control amount calculated by feedback control with a deviation between the air-fuel ratio AF and the target air-fuel ratio AFTr as an input. The larger the base injection quantity is, the larger the derived fuel injection quantity is. The larger the feedback control amount is, the more the derived fuel injection amount is. An upper limit is set for the feedback control amount. Therefore, the feedback control amount exceeding the upper limit is not calculated by the feedback control.

Here, when fuel having low combustibility is injected from the fuel injection valve 15, the absolute value of the deviation between the air-fuel ratio AF and the target air-fuel ratio AFTr tends to increase. That is, the absolute value of the feedback control amount tends to increase. At this time, when the state where the absolute value of the feedback control amount is equal to the upper limit continues for a predetermined time or more, it can be determined that fuel having low combustibility is injected from the fuel injection valve 15. When fuel having low combustibility is injected from the fuel injection valve 15, the mixture may not be stably combusted in the cylinder 11.

Therefore, if it is not determined in step S14 that the fuel injected from the fuel injection valve 15 is a fuel having high combustibility (no), the process proceeds to step S17. On the other hand, when it is determined that the fuel injected from the fuel injection valve 15 is a fuel having high combustibility (yes in S14), the process proceeds to the next step S15.

In step S15, it is determined whether or not the valve timing adjusting apparatus provided in the internal combustion engine 10 is operating normally. The valve timing adjusting apparatus is an apparatus that adjusts the opening/closing timing of an intake valve of the internal combustion engine 10. The valve timing adjusting apparatus is also referred to as "VVT". When the valve timing adjusting apparatus is under fail safe (fail safe), it is not determined that the valve timing adjusting apparatus is operating normally. On the other hand, if the protection device is not under the fail safe state, it is determined that the device is operating normally. If it is not determined in step S15 that the operation is normally performed (no), the process proceeds to step S17. On the other hand, if it is determined that the operation is normally performed (yes in S15), the process proceeds to the next step S16.

In step S16, the stable combustion flag FLG1 is set to active. That is, when all the determinations in steps S11 to S15 are yes, it is determined that the air-fuel mixture is being stably combusted in the cylinder 11. Then, the present processing routine is temporarily ended.

In step S17, the stable combustion flag FLG1 is set to inactive. That is, if any of steps S11 to S15 is determined as "no", it is not determined that the air-fuel mixture is being stably combusted in the cylinder 11. Then, the present processing routine is temporarily ended.

Next, a processing routine executed by the motor control unit 110 will be described with reference to fig. 4. This processing routine is repeatedly executed when the internal combustion engine is operated.

In the present processing routine, in the first step S21, it is determined whether or not the rapid-decrease processing is being executed by the rapid-decrease processing unit 133. If the sharp drop processing is not being executed (no in S21), the process proceeds to the next step S22. At step S22, it is determined whether or not vehicle speed VS is smaller than determination vehicle speed VSTh. The greater the vehicle speed VS, the greater the running sound of the vehicle. Then, as a criterion for determining whether or not the running sound is large, a determination vehicle speed VSTh is set. That is, when vehicle speed VS is smaller than determination vehicle speed VSTh, the running sound is small. When the vehicle speed VS is equal to or higher than the determination vehicle speed VSTh in step S22 (no), it can be determined that the traveling sound of the vehicle is large, and therefore the present processing routine is once ended. That is, neither the push-down processing nor the push-up processing is executed. On the other hand, when vehicle speed VS is smaller than determination vehicle speed VSTh (yes in S22), the process proceeds to next step S23.

In step S23, determination is made as to whether or not the stable combustion flag FLG1 is set to active. In the case where the stable combustion flag FLG1 is set to active (S23: yes), the process moves to the next step S24. Then, in step S24, the press-down process is executed. That is, in embodiment 1, the depression processing is executed when it is determined that the air-fuel mixture is being stably combusted in the cylinder 11. When the press-down process is executed, the present process routine is temporarily ended.

As described above, in the depression processing, the 1 st motor torque TQM1 is output from the 1 st motor generator 71. In the power distribution and integration mechanism 40, the sun gear 41 is a gear coupled to the 1 st motor/generator 71, and the pinion gear 43 is a gear coupled to the internal combustion engine 10. When the torque input from the internal combustion engine 10 to the pinion gear 43 during the engine operation is positive torque, the direction of the torque input from the sun gear 41 to the pinion gear 43 is opposite to the positive torque when the 1 st motor torque TQM1 is input to the sun gear 41. Therefore, in the case of performing the depressing process, the teeth of the sun gear 41 are pressed against the teeth of the pinion gear 43 from the rotational direction side of the pinion gear 43. This can suppress the occurrence of hunting in the power distribution/integration mechanism 40. Therefore, the generation of vibration and abnormal sound due to the rattling can be suppressed.

On the other hand, in the case where the stable combustion flag FLG1 is set to inactive in step S23 (no), the process moves to the next step S25. In step S25, a push-up process is executed. That is, in embodiment 1, the push-up process is executed when it is not determined that the air-fuel mixture is being stably combusted in the cylinder 11. When the push-up processing is executed, the present processing routine is temporarily ended.

As described above, when the push-up process is executed, the 1 st motor generator 71 outputs the 2 nd motor torque TQM2. In the power distribution/integration mechanism 40, the sun gear 41 is a gear coupled to the 1 st motor/generator 71, and the pinion gear 43 is a gear coupled to the internal combustion engine 10. When the torque input from the internal combustion engine 10 to the pinion gear 43 during the engine operation is positive torque, the direction of the torque input from the sun gear 41 to the pinion gear 43 when the 2 nd motor torque TQM2 is input to the sun gear 41 is the same as the positive torque. Therefore, in the case of performing the push-up process, the teeth of the sun gear 41 are pressed against the teeth of the pinion gear 43 from the side opposite to the rotation direction of the pinion gear 43. This can suppress the occurrence of hunting in the power distribution and integration mechanism 40. Therefore, the generation of vibration and abnormal sound due to the wobbling can be suppressed.

On the other hand, when the sharp drop process is being executed in step S21 (yes), the process proceeds to the next step S26. In step S26, it is determined whether or not the stored electric charge SOC of the battery 77 is smaller than the determination stored electric charge SOCTh. As a criterion for determining whether the state of the battery 77 is a state in which it is not preferable to further increase the storage amount SOC, the determination storage amount SOCTh is set. When the stored charge amount SOC is equal to or greater than the determined stored charge amount SOCTh, it is not preferable to further increase the stored charge amount SOC. Therefore, when the stored charge amount SOC is equal to or greater than the determination stored charge amount SOCTh in step S26 (no), the power generation process that is the process of step S27 is not executed, and the present processing routine is once ended. On the other hand, when the stored charge amount SOC is smaller than the determined stored charge amount SOCTh (YES in S26), the process proceeds to the next step S27. In step S27, power generation processing is executed. When the power generation processing is executed, the present processing routine is once ended.

In a situation where the rapid-decrease process is being executed, if the lower limit guard PELm is larger than the required engine output PEQ, the actual engine output PE may be larger than the required engine output PEQ. When actual engine output PE is larger than required engine output PEQ, vehicle speed VS is less likely to decrease. Therefore, in the power generation process, when the lower limit guard PELm is larger than the required engine output PEQ, the 1 st motor generator 71 is driven so that the amount of power generation by the 1 st motor generator 71 becomes an amount corresponding to the difference between the lower limit guard PELm and the required engine output PEQ. As a result, an output corresponding to the difference between the actual engine output PE and the required engine output PEQ is consumed by the electric power generation in the 1 st motor generator 71.

In the case where the lower limit guard PELm is equal to or less than the required engine output PEQ even during execution of the emergency lowering process, the 1 st motor generator 71 is driven so that the amount of power generation by the 1 st motor generator 71 becomes "0 (zero)" in the power generation process.

Next, a processing routine executed by the rapid-decrease processing unit 133 will be described with reference to fig. 5. The present processing routine is not repeatedly executed when the fuel cut processing is executed during the operation of the internal combustion engine.

In the present processing routine, in the first step S31, a determination is made as to whether or not the decrease amount Δ PEQ of the requested engine output PEQ is equal to or greater than the determination decrease amount Δ PEQTh. The determination decrease amount Δ PEQTh is a criterion for determining whether the engine output PEQ is required to be greatly decreased.

In general, when the engine output PEQ is requested to be reduced, the throttle opening SL is also reduced. Further, the EGR opening degree regrr decreases in accordance with a decrease in the throttle opening degree SL. At this time, if the responsiveness of the EGR valve 22 is lower than the responsiveness of the throttle valve 13, the EGR rate Y becomes higher due to the delay in the response of the EGR valve 22. When the EGR rate Y becomes extremely high in a state where the required engine output PEQ is small, the proportion of the intake air in the gas introduced into the cylinder 11 becomes extremely small, and therefore, there is a possibility that misfire occurs in the internal combustion engine 10.

When the reduction amount Δ PEQ is equal to or larger than the determination reduction amount Δ PEQTh, the engine output PEQ is required to be greatly reduced, so that the proportion of the intake air in the gas introduced into the cylinder 11 becomes extremely small when the normal processing is performed, and there is a possibility that misfire occurs in the engine 10. On the other hand, when the decrease amount Δ PEQ is smaller than the determination decrease amount Δ PEQTh, the engine output PEQ is required not to decrease, or the decrease amount Δ PEQ is required to decrease but is not so large. Therefore, even if the normal process is performed, the proportion of the intake air in the gas introduced into the cylinder 11 does not become extremely small, and no misfire occurs in the internal combustion engine 10.

Therefore, when the decrease amount Δ PEQ is equal to or larger than the determination decrease amount Δ PEQTh in step S31 (yes), the rapid decrease processing is started. That is, the reduction amount Δ PEQ is a condition for determining that the reduction amount Δ PEQTh or more is the start of the rapid-decrease processing. On the other hand, when the decrease amount Δ PEQ is smaller than the determination decrease amount Δ PEQTh (S31: no), the process proceeds to step S36 described later.

In the rapid decrease processing, in the first step S32, the target engine output PETr is set. That is, the larger one of the required engine output PEQ and the lower limit guard PELm is set as the target engine output PETr. The lower limit guard PELm used for setting the target engine output PETr is set by the guard setting unit 134. Then, in step S33, a value corresponding to the target engine output PETr is set as a target throttle opening XSL that is a target of the throttle opening SL. That is, the smaller the target engine output PETr, the smaller the target throttle opening XSL. Therefore, in the case where the target engine output PETr is larger than the required engine output PEQ because the lower limit guard PELm is larger than the required engine output PEQ, the target throttle opening XSL is larger than the opening corresponding to the required engine output PEQ. That is, the reduction of the target throttle opening degree XSL is restricted.

In the next step S34, a value corresponding to the requested engine output PEQ is set as the target EGR opening degree XEGR, which is the target of the EGR opening degree regrr. That is, the smaller the required engine output PEQ, the smaller the target EGR opening degree XEGR. The target throttle valve opening amount XSL is set to a value corresponding to the target engine output PETr, whereas the target EGR opening amount XEGR is set to a value corresponding to the required engine output PEQ. That is, in the rapid-decrease process, the decrease in the target EGR opening degree XEGR is executed with priority over the decrease in the target throttle opening degree XSL.

Then, in step S35, the throttle valve 13 is controlled based on the target throttle opening amount XSL, and the EGR valve 22 is controlled based on the target EGR opening amount XEGR. Thus, throttle valve opening degree SL and EGR opening degree regrr are reduced so that the reduction rate of EGR opening degree regrr is higher than the reduction rate of throttle valve opening degree SL. When the jerk-down processing is executed in this manner, the present processing routine is temporarily ended.

In step S36, it is determined whether or not the quick lowering process is being executed. If the rapid-decrease processing is not being executed (no in S36), the present processing routine is once ended. In this case, the throttle valve opening degree SL and the EGR opening degree REGR are respectively adjusted by executing normal processing. On the other hand, when the sharp drop process is being executed in step S36 (yes), the process proceeds to the next step S37.

In step S37, it is determined whether or not the end condition of the rapid decrease processing is satisfied. That is, when it can be determined that the EGR opening degree REGR is the opening degree corresponding to the required engine output PEQ, it is determined that the end condition is satisfied. Even if the target EGR opening degree XEGR is changed in accordance with the change in the requested engine output PEQ, the change in the EGR opening degree regrr is delayed with respect to the change in the requested engine output PEQ. Therefore, the EGR opening degree regrr is estimated in consideration of the delay.

For example, in the case where the accelerator operation by the driver is released and the minimum value that can be generated as the engine output PE during the engine operation is set as the required engine output PEQ, "0 (zero)" is set as the EGR opening degree regrr corresponding to the required engine output PEQ. Therefore, when the accelerator operation is released, it is determined that the end condition of the rapid decrease processing is satisfied when the closing of the EGR valve 22 is completed.

If it is not determined in step S37 that the termination condition is satisfied (no), the process proceeds to step S32. That is, the rapid decrease processing is continuously performed. On the other hand, if it is determined that the termination condition is satisfied (yes in S37), the sharp drop processing is terminated, and the present processing routine is once terminated. After that, the throttle valve opening degree SL and the EGR opening degree regrr are adjusted by executing normal processing, respectively.

Next, a processing routine executed by the ignition timing adjusting unit 135 will be described with reference to fig. 6. The present processing routine is repeatedly executed without executing the fuel cut processing during the operation of the internal combustion engine.

In the present processing routine, first, in step S41, it is determined whether or not the quick-decrease processing is being executed. If the rapid decrease process is not being executed (S41: no), the ignition timing retard process is not executed and the present process routine is once ended. On the other hand, in the case where the jerk-down process is being executed (S41: YES), the process proceeds to the next step S42.

In step S42, it is determined whether or not the stored charge amount SOC of the battery 77 is equal to or greater than the determined stored charge amount SOCTh. When the stored charge amount SOC is smaller than the determination stored charge amount SOCTh (no in S42), the power generation process is executed, and therefore, the present process routine is once ended. That is, the ignition timing retard process is not executed. On the other hand, when the stored charge SOC is equal to or greater than the determination stored charge SOCTh (yes in S42), the power generation process is not executed even during the execution of the sudden decrease process, and therefore the process proceeds to the next step S43.

In step S43, the ignition timing retarding process is executed. The more retarded the ignition timing TINJ, the more the engine output PE can be reduced. In the case where the rapid decrease process is executed, when the target engine output PETr is larger than the required engine output PEQ, the actual engine output PE is larger than the required engine output PEQ. Therefore, in the ignition timing retard process, the ignition timing TINJ is retarded by an amount corresponding to the difference between the target engine output PETr and the required engine output PEQ, as compared to when the ignition timing retard process is not executed. That is, the larger the difference is, the larger the retard amount of the ignition timing TINJ is. Then, the present processing routine is temporarily ended.

Next, a processing routine executed by the injection valve control unit 136 will be described with reference to fig. 7. This processing routine is repeatedly executed when the internal combustion engine is operated.

In the present processing routine, first, in step S51, it is determined whether or not the quick-decrease processing is being executed. If the sharp drop process is being executed (yes in S51), the process proceeds to the next step S52. In step S52, it is determined whether or not the intake air amount GA is equal to or less than the determination intake air amount GATh.

When deposits adhere to the throttle valve 13, the intake air amount GA may be smaller than an amount corresponding to the throttle opening SL. If the intake air amount GA is too small, the amount of fuel supplied into the cylinder 11 also becomes small, and therefore, there is a possibility that misfire may occur in the internal combustion engine 10. Therefore, the determination intake air amount GATh is set as a criterion for determining whether or not there is a possibility of occurrence of misfire due to the small intake air amount GA.

If the intake air amount GA is greater than the determined intake air amount GATh in step S52 (no), the present processing routine is once ended. In this case, the jerk-down process is continuously executed. On the other hand, when the intake air amount GA is equal to or less than the determination intake air amount GATh (yes in S52), the process proceeds to the next step S53. In step S53, it is determined whether or not the state where the intake air amount GA is equal to or less than the determination intake air amount GATh continues for the determination duration TMTh or more. When the duration in which the intake air amount GA is equal to or less than the determination intake air amount GATh is shorter than the determination duration TMTh (no in S53), it can be determined that the misfire has not occurred in the internal combustion engine 10, and therefore the present processing routine is once ended. On the other hand, when the duration in which the intake air amount GA is equal to or less than the judgment intake air amount GATh is equal to or more than the judgment duration TMTh (yes in S53), it can be judged that there is a possibility of misfire occurring in the internal combustion engine 10, and the process proceeds to the next step S54.

The larger the amount of EGR gas recirculated to the intake passage 12, the more likely misfire occurs. Further, the smaller the intake air amount GA, the more likely misfire occurs. Further, the higher the engine speed NE, the more likely misfire occurs. In embodiment 1, the shorter the time period for which misfire is likely to occur in the internal combustion engine 10, the shorter the time period is set as the determination duration TMTh. That is, the determination duration TMTh is set to be shorter as the amount of EGR gas recirculated to the intake passage 12 by the EGR device 20 is larger. The shorter the intake air amount GA is, the shorter the time is set as the determination duration TMTh. Further, as the engine speed NE is higher, a shorter time is set as the determination duration TMTh.

When some of the EGR ports 211 among the plurality of EGR ports 211 are closed, misfire may occur in the cylinder 11 having the EGR rate Y higher than the EGR rate Y in the other cylinders 11 when the required engine output PEQ is greatly reduced. Therefore, when the blockage diagnosis unit 137 diagnoses that the blocked EGR port 211 is present, a shorter time is set as the determination duration TMTh than when the blockage diagnosis unit does not diagnose that the blocked EGR port 211 is present.

In step S54, a fuel cut process is executed. Then, this processing routine is temporarily ended. When the fuel cut processing is started as the intake air amount GA becomes equal to or less than the determined intake air amount GATh by executing the rapid decrease processing in this manner, the processing routine shown in fig. 5 is not executed. That is, the jerk-down process is not executed any more. Then, the throttle valve opening degree SL and the EGR opening degree regrr are adjusted by normal processing. Further, when the power generation process is executed in association with the execution of the rapid-decrease process, the power generation process is not executed when the rapid-decrease process is ended due to the execution of the fuel cut process. Further, when the ignition timing retard process is executed in association with the execution of the rapid-decrease process, the ignition timing retard process is not executed when the rapid-decrease process is ended by the execution of the fuel cut process.

On the other hand, if the sharp drop process is not executed in step S51 (no), the process proceeds to the next step S55. In step S55, a determination is made as to whether or not the fuel cut-off process is being executed. When the fuel cut-off process is not being executed (S55: no), the present process routine is temporarily ended. On the other hand, in the case where the fuel cut-off process is being executed (S55: YES), the process proceeds to the next step S56.

In step S56, it is determined whether or not the EGR opening degree regrr is an opening degree corresponding to the requested engine output PEQ. If it is not determined that the EGR opening degree REGR is the opening degree corresponding to the requested engine output PEQ (S56: no), it is determined that the EGR opening degree REGR is still larger than the opening degree corresponding to the requested engine output PEQ, and the process proceeds to step S54. That is, the fuel cut process is continuously executed.

On the other hand, if it is determined in step S56 that the EGR opening degree regrr is the opening degree corresponding to the requested engine output PEQ (yes), the process proceeds to next step S57. In step S57, fuel injection from the fuel injection valve 15 is started again. That is, the fuel cut processing is ended. After that, the present processing routine is temporarily ended.

The operation and effect of embodiment 1 will be described.

(1) When it is not determined that the air-fuel mixture is being stably combusted in the cylinder 11 without executing the rapid decrease processing, the depression processing is not executed. Therefore, when the combustion of the air-fuel mixture in the cylinder 11 is unstable, the occurrence of misfire in the internal combustion engine 10 accompanying the execution of the depression processing can be suppressed. In embodiment 1, when it is not determined that the air-fuel mixture is being stably combusted in the cylinder 11, the push-up process is executed instead of the push-down process. By executing the push-up processing, the load applied to the internal combustion engine 10 by the driving of the 1 st motor generator 71 can be reduced. By operating the internal combustion engine with a reduced load in this manner, the fuel economy of the internal combustion engine 10 can be improved. In addition, compared to the case where the push-up process is not executed, the rattling within the power distribution and integration mechanism 40 can be suppressed. Therefore, the generation of vibration and abnormal sound due to the rattling in the power distribution and integration mechanism 40 can be suppressed.

(2) On the other hand, when it is determined that the air-fuel mixture is being stably combusted in the cylinder 11 without executing the rapid-decrease processing, the depression processing is executed. Therefore, the rattling motion in the power distribution and integration mechanism 40 can be suppressed. Therefore, the generation of vibration and abnormal sound due to the vibration in the power distribution and integration mechanism 40 can be suppressed.

(3) When the depression processing is executed, the load applied to the internal combustion engine 10 becomes large. Therefore, the fuel economy of the internal combustion engine 10 deteriorates. On the other hand, the higher the vehicle speed VS, the greater the running sound generated when the vehicle runs. Therefore, when vehicle speed VS is high, even if abnormal sound or vibration due to rattling of the gears meshing with each other at power split device 40 occurs, the occupant of the vehicle is less likely to feel uncomfortable. Therefore, in embodiment 1, when vehicle speed VS is equal to or greater than determination vehicle speed VSTh, the running sound generated during the running of the vehicle is large, and therefore, even if it is determined that the air-fuel mixture is being stably combusted in cylinder 11, the depression processing is not executed. This can reduce the execution opportunity of the push-down process. Therefore, deterioration of the fuel economy of the internal combustion engine 10 can be suppressed.

(4) If the proportion of the intake air in the gas introduced into the cylinder 11 of the internal combustion engine 10 is too small, misfire may occur in the internal combustion engine 10. Therefore, when the opening amount of the throttle valve 13 decreases due to a decrease in the required engine output, the opening amount of the EGR valve 22 decreases in accordance with the decrease in the opening amount of the throttle valve 13. However, in this case, the responsiveness of the EGR valve 22 is inferior to the responsiveness of the throttle valve 13, and therefore there is a possibility that the decrease in the amount of EGR gas recirculated to the intake passage 12 is delayed with respect to the decrease in the amount of intake air caused by the decrease in the opening degree of the throttle valve 13. If such a delay occurs, the proportion of the intake air in the gas introduced into the cylinder 11 may be too small, and a misfire may occur in the internal combustion engine 10.

Based on this, according to embodiment 1, when the reduction amount Δ PEQ is equal to or larger than the determination reduction amount Δ PEQTh, the throttle valve opening amount SL and the EGR opening amount REGR are reduced by performing the rapid decrease processing so that the reduction speed of the EGR opening amount REGR becomes higher than the reduction speed of the throttle valve opening amount SL. By preferentially decreasing the EGR opening degree regrr over the throttle opening degree SL in this way, it is possible to suppress a delay in the decrease in the amount of EGR gas recirculated to the intake passage 12 relative to the decrease in the intake air caused by the decrease in the throttle opening degree SL. As a result, the proportion of the intake air in the gas introduced into the cylinder 11 can be suppressed from becoming too small. Therefore, it is possible to suppress the occurrence of misfire in the internal combustion engine 10 when the required engine output PEQ is reduced.

(5) In the emergency lowering process, when the lower limit guard PELm is larger than the required engine output PEQ, the target throttle opening XSL is set to an opening corresponding to the lower limit guard PELm. Thereby, the reduction of the throttle opening SL is restricted, so the reduction of the intake air amount GA can be suppressed. Therefore, the proportion of the intake air in the gas introduced into the cylinder 11 can be suppressed from becoming too small. That is, the occurrence of misfire in the internal combustion engine 10 can be suppressed. Further, by executing the power generation processing when the lower limit guard PELm is larger than the required engine output PEQ, the driving of the 1 st motor/generator 71 is controlled so that the amount of power generation becomes an amount corresponding to the difference between the lower limit guard PELm and the required engine output PEQ. This can suppress a decrease in controllability of the torque transmitted to the drive wheels 62 of the vehicle.

(6) If the intake air amount is significantly reduced in a state where the EGR rate is high, the ratio of the intake air in the gas introduced into the cylinder 11 tends to be too small. According to embodiment 1, the lower limit guard PELm is set to be smaller as the EGR rate Y becomes lower. That is, when the EGR rate Y is high, the lower limit guard PELm is set to be large, so the intake air amount GA is not easily reduced. As a result, the proportion of the intake air in the gas introduced into the cylinder 11 can be suppressed from becoming too small. This can suppress the occurrence of misfire in the internal combustion engine 10.

On the other hand, when the EGR rate Y becomes lower due to a decrease in the EGR opening degree regrr, the lower limit guard PELm becomes smaller. When the lower limit protection PELm is reduced as described above, the throttle opening degree SL is also reduced. As a result, the engine output PE can be reduced. Therefore, the deviation of the engine output PE from the required engine output PEQ can be reduced.

(7) When the stored charge amount SOC of the battery 77 is smaller than the determined stored charge amount SOCTh during execution of the sudden decrease processing, it is determined that the electric power generated by the motor generators 71 and 72 during execution of the sudden decrease processing can be stored in the battery 77, and the power generation processing is executed. On the other hand, when the power generation process is executed when the stored charge amount SOC is equal to or greater than the determined stored charge amount SOCTh, the stored charge amount of the battery 77 may become excessive. Therefore, when the stored charge amount SOC of the battery 77 is equal to or greater than the determined stored charge amount SOCTh, the ignition timing retard process is executed without executing the power generation process during the execution of the rapid-decrease process. In this case, by executing the ignition timing retarding process to retard the ignition timing TINJ, it is possible to suppress a deviation of the engine output PE from the required engine output PEQ. As a result, even if the power generation process is not executed, it is possible to suppress a decrease in controllability of the torque transmitted to the drive wheels 62 of the vehicle.

(8) When the intake air amount GA is smaller than the determination intake air amount GATh, the intake air amount GA may become too small to cause misfire in the internal combustion engine 10. Therefore, when the intake air amount GA is smaller than the determination intake air amount GATh when the throttle opening SL is reduced by executing the rapid decrease processing, the rapid decrease processing is ended and the fuel cut processing is started on the condition that the state where the intake air amount GA is smaller than the determination intake air amount GATh continues for the determination duration TMTh or longer. When the fuel cut process is executed, the fuel injection is stopped, so no more unburned fuel reaches the three-way catalyst 17. As a result, the temperature of the three-way catalyst 17 can be suppressed from becoming excessively high.

(9) As the possibility of misfire occurring in the internal combustion engine 10 increases, a shorter time is set as the determination duration TMTh. By varying the determination duration TMTh in this manner, the fuel cut processing can be started earlier as the possibility of misfire increases.

(11) Some EGR ports 211 of the plurality of EGR ports 211 may be blocked. In this case, the EGR gas does not flow back to the branch passage portion 12A through the blocked EGR port 211. On the other hand, a large amount of EGR gas flows back from the unblocked EGR port 211 to the branch passage portion 12A. That is, the proportion of the EGR gas in the gas introduced into the cylinder 11 fluctuates for each cylinder 11. Misfire is likely to occur in the cylinder 11 having a large proportion of EGR gas. In this regard, according to embodiment 1, when it is diagnosed that there is a blocked EGR port 211, a shorter time is set as the determination duration TMT than when it is not diagnosed that there is a blocked EGR port 211. Thus, when the EGR port 211 is blocked, misfire is more likely to occur than when the EGR port 211 is not blocked, and therefore the fuel cut process can be started early.

(embodiment 2)

Next, a control device for a hybrid vehicle according to embodiment 2 will be described with reference to fig. 8. In embodiment 2, the processing contents in the injection valve control unit 136 are different from those in embodiment 1. In the following description, the portions different from the above embodiment 1 will be mainly described, and the same reference numerals are given to the same or corresponding components as those in the above embodiment 1, and redundant description will not be repeated.

A processing routine executed by the injection valve control unit 136 will be described with reference to fig. 8. This processing routine is repeatedly executed when the internal combustion engine is operated.

In the present processing routine, in the first step S61, it is determined whether or not the rapid-decrease processing is being executed by the rapid-decrease processing unit 133. If the sharp drop process is being executed (yes in S61), the process proceeds to the next step S62. In step S62, it is determined whether or not the intake air amount GA is equal to or less than the determined intake air amount GATh, in the same manner as in step S52.

If the intake air amount GA is larger than the determination intake air amount GATh in step S62 (no), the present processing routine is once ended. In this case, the jerk-down process is continuously executed. On the other hand, when the intake air amount GA is equal to or less than the determination intake air amount GATh (yes in S62), the process proceeds to the next step S63. In step S63, similarly to step S53 described above, determination is made as to whether or not the state where the intake air amount GA is equal to or less than the determination intake air amount GATh continues for the determination duration TMTh or more. When the duration in which the intake air amount GA is equal to or less than the determination intake air amount GATh is shorter than the determination duration TMTh (no in S63), it can be determined that the misfire has not occurred in the internal combustion engine 10, and therefore the present processing routine is once ended. On the other hand, when the duration in which the intake air amount GA is equal to or less than the judgment intake air amount GATh is equal to or more than the judgment duration TMTh (yes in S63), it can be judged that there is a possibility of misfire occurring in the internal combustion engine 10, and the process proceeds to the next step S64.

In step S64, an air-fuel ratio enrichment process is executed. In the air-fuel ratio enrichment process, an air-fuel ratio richer than the stoichiometric air-fuel ratio AFSt is set as a target air-fuel ratio AFTr that is a target of the air-fuel ratio AF. In addition, air-fuel ratio control based on the target air-fuel ratio AFTr is performed. This makes it possible to set the air-fuel ratio AF to a value richer than the stoichiometric air-fuel ratio AFSt. Then, this processing routine is temporarily ended.

Here, the larger the amount of EGR gas recirculated to the intake passage 12, the more likely misfire occurs. Further, the smaller the intake air amount GA, the more likely misfire occurs. Further, the higher the engine speed NE, the more likely misfire occurs. The richer the air-fuel ratio AF is set to the value on the rich side within the predetermined air-fuel ratio range including the stoichiometric air-fuel ratio AFSt, the more difficult it is for misfire to occur in the internal combustion engine 10.

Therefore, in the air-fuel ratio enrichment process, the target air-fuel ratio AFTr is set such that the difference between the target air-fuel ratio AFTr and the stoichiometric air-fuel ratio AFSt becomes larger as the possibility of misfire occurring in the internal combustion engine 10 increases. That is, as the amount of EGR gas recirculated to the intake passage by the EGR device 20 increases, the air-fuel ratio on the richer side is set as the target air-fuel ratio AFTr. Further, the smaller the intake air amount GA, the richer air-fuel ratio is set as the target air-fuel ratio AFTr. Further, as the engine speed NE is higher, the air-fuel ratio on the richer side is set as the target air-fuel ratio AFTr.

When the air-fuel ratio enrichment process is started as a result of the execution of the spike decrease process such that the intake air amount GA becomes equal to or less than the determined intake air amount GATh, the process routine shown in fig. 5 is not executed. That is, the jerk-down process is not executed any more. Then, the throttle valve opening degree SL and the EGR opening degree regrr are adjusted by normal processing. In addition, when the power generation process is executed in association with the execution of the air-fuel ratio enrichment process, the power generation process is not executed when the rapid decrease process is ended due to the execution of the air-fuel ratio enrichment process. Further, when the ignition timing retarding process is executed in association with the execution of the rapid decrease process, the ignition timing retarding process is not executed any more when the rapid decrease process is ended by the execution of the air-fuel ratio enriching process.

On the other hand, in step S61, if the sharp drop processing is not being executed (no), the processing proceeds to next step S65. In step S65, a determination is made as to whether or not the air-fuel ratio enrichment process is being executed. When the air-fuel ratio enrichment process is not being executed (S65: no), the present process routine is once ended. On the other hand, when the air-fuel ratio enrichment process is being executed (S65: YES), the process proceeds to the next step S66.

In step S66, it is determined whether or not the EGR opening degree regrr is an opening degree corresponding to the requested engine output PEQ. If it is not determined that the EGR opening degree regrr is the opening degree corresponding to the requested engine output PEQ (no in S66), it is determined that the EGR opening degree regrr is still larger than the opening degree corresponding to the requested engine output PEQ, and the process proceeds to step S64. That is, the air-fuel ratio enrichment process is continuously executed.

On the other hand, if it is determined in step S66 that the EGR opening degree regrr is the opening degree corresponding to the requested engine output PEQ (yes), the process proceeds to next step S67. In step S67, the stoichiometric air-fuel ratio AFSt is set to the target air-fuel ratio AFTr. That is, the air-fuel ratio enrichment processing is ended. After that, the present processing routine is temporarily ended.

In embodiment 2, the following effects can be obtained in addition to the effects equivalent to the above-described effects (1) to (7).

(10) When the intake air amount GA is smaller than the determination intake air amount GATh, the intake air amount GA may become too small to cause misfire in the internal combustion engine 10. Therefore, when the intake air amount GA is smaller than the determination intake air amount GATh when the throttle opening SL is reduced by executing the rapid decrease processing, the rapid decrease processing is ended and the air-fuel ratio enrichment processing is started on the condition that the state in which the intake air amount GA is smaller than the determination intake air amount GATh continues for the determination duration TMTh or longer. Accordingly, the air-fuel ratio AF can be set to a value richer than the stoichiometric air-fuel ratio AFSt. Thus, compared to the case where the stoichiometric air-fuel ratio AFSt is set to the target air-fuel ratio AFTr, misfire is less likely to occur in the internal combustion engine 10. As a result, the amount of unburned fuel that reaches the three-way catalyst 17 due to misfire can be suppressed from increasing. Therefore, the temperature of the three-way catalyst 17 can be suppressed from becoming excessively high.

(11) The larger the amount of EGR gas recirculated to the intake passage 12, the more likely misfire occurs in the internal combustion engine 10. Further, the smaller the intake air amount is, the more likely the misfire occurs. Further, misfire is more likely to occur as the engine speed is higher. In this regard, according to embodiment 2, the air-fuel ratio in the air-fuel ratio enrichment process can be set to a value corresponding to the amount of EGR gas recirculated to the intake passage by the EGR apparatus, the intake air amount, and the engine speed. That is, the air-fuel ratio on the richer side is set as the target air-fuel ratio AFTr as the probability of misfire occurring in the internal combustion engine 10 is higher. Therefore, the effect of suppressing the occurrence of misfire obtained by executing the air-fuel ratio enrichment process can be improved.

(12) The shorter the time period as the possibility of misfire occurring in the internal combustion engine 10 is higher, the determination duration TMTh is set. By varying the determination duration TMTh in this manner, the air-fuel ratio enrichment process can be started earlier as the possibility of misfire increases.

The above embodiments can be modified and implemented as follows. The above embodiments and the following modifications can be combined and implemented within a range not technically contradictory to each other.

In embodiment 2, in the air-fuel ratio enrichment process, the target air-fuel ratio AFTr may not be changed according to the intake air amount GA as long as the target air-fuel ratio AFTr is changed according to the amount of the EGR GAs recirculated to the intake passage 12 by the EGR device 20. Similarly, in the air-fuel ratio enrichment process, the target air-fuel ratio AFTr may not be made variable in accordance with the engine speed NE as long as the target air-fuel ratio AFTr is made variable in accordance with the amount of EGR gas recirculated to the intake passage by the EGR device 20.

In embodiment 2, as long as the target air-fuel ratio AFTr is made variable in accordance with the intake air amount GA in the air-fuel ratio enrichment process, the target air-fuel ratio AFTr may not be made variable in accordance with the amount of EGR GAs that is recirculated to the intake passage 12 by the EGR device 20. Similarly, in the air-fuel ratio enrichment process, the target air-fuel ratio AFTr may not be changed according to the engine speed NE as long as the target air-fuel ratio AFTr is changed according to the intake air amount GA.

In embodiment 2, as long as the target air-fuel ratio AFTr is made variable in accordance with the engine speed NE in the air-fuel ratio enrichment process, the target air-fuel ratio AFTr may not be made variable in accordance with the amount of EGR gas that is recirculated to the intake passage 12 by the EGR device 20. Similarly, in the air-fuel ratio enrichment process, the target air-fuel ratio AFTr may not be changed according to the intake air amount GA as long as the target air-fuel ratio AFTr is changed according to the engine speed NE.

In embodiment 2, if the air-fuel ratio richer than the stoichiometric air-fuel ratio AFSt can be set as the target air-fuel ratio AFTr in the air-fuel ratio enrichment process, the target air-fuel ratio AFTr in the air-fuel ratio enrichment process may not be changed.

In embodiment 2, when the air-fuel ratio enrichment process is started, the spike decrease process is ended. However, the spike reduction process may be continuously executed even if the air-fuel ratio enrichment process is started. Even in this case, the occurrence of misfire in the internal combustion engine 10 can be suppressed. In this way, even if the air-fuel ratio enrichment process is started, if the rapid-decrease process is continued, the processes that have been performed before the start of the air-fuel ratio enrichment process in the power generation process and the ignition timing retardation process can be continued.

In embodiment 2, if the fuel injection is stopped immediately when the misfire is detected during the execution of the rapid decrease processing, the air-fuel ratio enrichment processing may not be executed even if the intake air amount GA becomes equal to or less than the judgment intake air amount GATh.

In embodiment 1, the fuel cut processing may be started after the misfire is detected during the execution of the rapid-decrease processing.

The determination duration TMTh may not be changed according to the diagnosis result of the occlusion diagnosis unit 137.

The determination duration TMTh may not be made variable according to the intake air amount GA as long as the determination duration TMTh is made variable according to the amount of EGR GAs recirculated to the intake passage 12 by the EGR device 20. Similarly, the determination duration TMTh may not be made variable in accordance with the engine speed NE as long as the determination duration TMTh is made variable in accordance with the amount of EGR gas recirculated to the intake passage 12 by the EGR device 20.

The determination duration TMTh may not be made variable according to the amount of EGR GAs recirculated to the intake passage 12 by the EGR device 20, as long as the determination duration TMTh is made variable according to the intake air amount GA. Similarly, the determination duration TMTh may not be made variable according to the engine speed NE as long as the determination duration TMTh is made variable according to the intake air amount GA.

The determination duration TMTh may not be made variable according to the amount of EGR gas recirculated to the intake passage 12 by the EGR device 20, as long as the determination duration TMTh is made variable according to the engine speed NE. Similarly, the determination duration TMTh may not be made variable according to the intake air amount GA as long as the determination duration TMTh is made variable according to the engine speed NE.

The determination duration TMTh may also be fixed to a certain value.

In embodiment 2, when the intake air amount GA is equal to or less than the determined intake air amount GATh during execution of the sudden decrease processing, the air-fuel ratio enrichment processing may be started immediately after the detection that the intake air amount GA is equal to or less than the determined intake air amount GATh.

In embodiment 1, when the intake air amount GA is equal to or less than the determined intake air amount GATh during execution of the sudden decrease processing, the fuel cut processing may be started immediately after the intake air amount GA is detected to be equal to or less than the determined intake air amount GATh.

During execution of the emergency lowering process, the lower limit guard PELm is made variable in accordance with a change in the EGR rate Y. However, the lower limit guard PELm may be maintained until the reduction of the EGR opening degree regrr is completed during the execution of the rapid decrease processing. Further, after the reduction of the EGR opening degree REGR is completed, the holding of the lower limit protection PELm may be released, and the throttle opening degree SL may be reduced.

In addition, during the execution of the emergency lowering processing, the lower limit guard PELm may be held until a predetermined time elapses from the start time point of the emergency lowering processing, and the lower limit guard PELm may be gradually reduced after the predetermined time elapses.

During execution of the emergency lowering process, when the lower limit protection PELm is larger than the required engine output PEQ, the battery 77 may not be charged by the power generation process. In this case, the ignition timing retard process may be executed regardless of the stored charge amount SOC in a situation where the lower limit guard PELm is larger than the required engine output PEQ.

In the rapid decrease process, the lower limit guard PELm may not be used as long as the decrease rate of the EGR opening degree regrr can be made higher than the decrease rate of the throttle valve opening degree SL. For example, in the spike-down process, the EGR valve 22 is closed. At this time, the throttle opening SL may be maintained until the EGR valve 22 is closed. That is, the decrease in the throttle opening SL may also be started after the EGR valve 22 is closed.

When the reduction of the throttle opening SL is started after the EGR valve 22 is closed in this way, there is a period during which the actual engine output PE is higher than the required engine output PEQ. During this period, the power generation process may be executed. In this case, it is preferable to drive the 1 st motor/generator 71 such that the larger the difference between the actual engine output PE and the required engine output PEQ, the larger the amount of power generation.

The determination stored electric energy amount SOCTh may be made variable. For example, when it can be predicted that the amount of power generation of the 1 st motor generator 71 increases when the rapid decrease process is executed, the determination charge amount SOCTh may be decreased as compared with other cases.

The rapid decrease processing may not be executed as long as the fuel injection is stopped immediately after the misfire is detected in the internal combustion engine 10 when the required engine output PEQ is greatly reduced.

When vehicle speed VS is equal to or higher than determination vehicle speed VSTh, the execution of the depression processing may not be prohibited.

When vehicle speed VS is equal to or higher than determination vehicle speed VSTh, execution of the push-up process may not be prohibited.

When it is not determined that the mixture is being stably combusted in the cylinder 11, not only the push-down process but also the push-up process may not be executed. By adopting such a control configuration, the occurrence of misfire in the internal combustion engine 10 can be suppressed as compared with the case where the depression processing is executed even when the combustion of the air-fuel mixture is unstable.

The hybrid vehicle to which control device 100 is applied may be a vehicle having a configuration different from that of the hybrid vehicle shown in fig. 1, as long as it has an internal combustion engine and a motor generator as power sources of the vehicle and is capable of inputting an output torque of the internal combustion engine to the motor generator via a power split device.

Claims

1. A control device for a hybrid vehicle,

the hybrid vehicle is provided with:

an internal combustion engine;

a motor generator; and

a power split mechanism having a plurality of gears meshing with each other,

the hybrid vehicle is configured to generate electric power by inputting an output torque of the internal combustion engine to the motor generator via the power split device,

the control device is provided with:

a combustion determination unit configured to determine whether or not an air-fuel mixture is being stably combusted in a cylinder of an internal combustion engine during operation of the internal combustion engine; and

a motor control unit configured to control the motor generator,

the motor control part is configured to be able to,

executing a depression process of causing the motor generator to output a torque in a direction in which a load applied to the internal combustion engine is increased when it is determined that the air-fuel mixture is being stably combusted in the cylinder,

the depression processing is not executed when it is not determined that the air-fuel mixture is being stably combusted in the cylinder.

2. The control device of the hybrid vehicle according to claim 1,

in the case where the torque output from the motor generator by performing the depression processing is set to the 1 st motor torque,

the motor control part is configured to be able to,

executing, when it is not determined that the air-fuel mixture is being stably combusted in the cylinder, a push-up process that is a process of causing a 2 nd motor torque, which is a torque in a direction opposite to a direction of the 1 st motor torque, to be output from the motor generator.

3. The control device of the hybrid vehicle according to claim 1,

the motor control part is configured to control the motor,

when the vehicle speed is equal to or higher than the determination vehicle speed, the depression processing is not executed even if it is determined that the air-fuel mixture is being stably combusted in the cylinder.

4. The control device of the hybrid vehicle according to any one of claims 1 to 3,

the internal combustion engine is provided with:

an EGR device that recirculates exhaust gas discharged from the inside of the cylinder to the exhaust passage to the intake passage as EGR gas;

a catalyst provided in the exhaust passage; and

an EGR valve provided in the EGR device and adjusting an amount of EGR gas recirculated to the intake passage,

the control device is provided with:

a normal processing unit configured to adjust an opening degree of a throttle valve provided in the intake passage and an opening degree of the EGR valve in accordance with a change in the required engine output when a decrease amount of the required engine output, which is a required output to the engine, is smaller than a determination decrease amount; and

a rapid decrease processing unit configured to execute a rapid decrease process of decreasing the opening degree of the throttle valve and the opening degree of the EGR valve so that a decrease speed of the opening degree of the EGR valve is higher than a decrease speed of the opening degree of the throttle valve, when an amount of decrease in the required engine output is equal to or larger than the determination decrease amount.

5. The control device of the hybrid vehicle according to claim 4,

the rapid reduction processing unit is configured to reduce the amount of the gas,

by the rapid decrease process, the opening amount of the throttle valve is decreased after the EGR valve is closed.

6. The control device of the hybrid vehicle according to claim 4,

the rapid-decrease processing unit is configured to,

the throttle valve opening degree is adjusted so as to be an opening degree corresponding to a larger value of the required engine output and the lower limit guard by the rapid decrease processing,

the motor control part is configured to be able to,

and executing power generation processing of driving the motor generator so that the amount of power generation by the motor generator becomes an amount corresponding to a difference between the lower limit guard and the required engine output when the lower limit guard is larger than the required engine output.

7. The control device of the hybrid vehicle according to claim 6,

the control device may further include a protection setting unit configured to set the lower limit protection so that the higher the EGR rate during execution of the rapid-decrease process, the larger the lower limit protection.

8. The control device of the hybrid vehicle according to claim 6 or 7,

the control device further includes an ignition timing adjustment unit configured to adjust an ignition timing of the internal combustion engine,

the motor control part is configured to control the motor,

the power generation process is executed when the sudden decrease process is executed in a situation where the stored amount of the battery that stores the electric power generated by the motor generator is smaller than the determination stored amount,

when the sudden decrease processing is executed in a situation where the stored electricity amount is equal to or greater than the determined stored electricity amount, the power generation processing is not executed,

the ignition timing adjusting section is configured to be,

when the rapid-decrease processing is executed in a situation where the stored electricity amount is equal to or greater than the determined stored electricity amount, ignition timing retard processing is executed that suppresses a deviation of the engine output from the required engine output by retarding the ignition timing.

9. The control device of the hybrid vehicle according to claim 4,

the control device further includes an injection valve control unit configured to control a fuel injection valve of the internal combustion engine,

the injection valve control section is configured to control the injection valve,

when the opening degree of the throttle valve is reduced by executing the rapid-decrease processing, a fuel cut processing for stopping fuel injection from the fuel injection valve is started on the condition that an intake air amount is equal to or less than a determination intake air amount.

10. The control device of the hybrid vehicle according to claim 9,

starting the fuel cut processing on condition that a duration of a state in which an intake air amount is smaller than the determined intake air amount is equal to or longer than a determination duration when the opening degree of the throttle valve is reduced by executing the rapid-decrease processing,

the determination duration is set such that the determination duration is shorter as the amount of EGR gas recirculated to the intake passage by the EGR device is larger, the determination duration is shorter as the intake air amount is smaller, and the determination duration is shorter as the engine speed is higher.

11. The control device of the hybrid vehicle according to claim 10,

the internal combustion engine has a plurality of cylinders,

a downstream portion of the intake passage is configured to branch off for each of the cylinders,

in the case where a passage portion branched for each of the cylinders in the intake passage is set as a branch passage portion, the EGR device has a plurality of EGR ports connected to a plurality of the branch passage portions,

the control device includes a blockage diagnosis unit configured to diagnose whether a blocked EGR port is present among the plurality of EGR ports,

the determination duration is set such that, when the presence of a blocked EGR port is diagnosed, the determination duration is shorter than when the presence of a blocked EGR port is not diagnosed.

12. The control device of the hybrid vehicle according to claim 4,

when the opening degree of the throttle valve is reduced by executing the rapid-decrease processing, an air-fuel ratio enrichment processing is executed on the condition that an intake air amount is equal to or less than a determination intake air amount, and the air-fuel ratio enrichment processing is processing for controlling the fuel injection valve so that an air-fuel ratio becomes a value on a rich side.

13. The control device of the hybrid vehicle according to claim 12,

the fuel injection valve is controlled by the air-fuel ratio enrichment process such that the air-fuel ratio becomes richer as the amount of EGR gas recirculated to the intake passage by the EGR device increases, the air-fuel ratio becomes richer as the amount of intake air decreases, and the air-fuel ratio becomes richer as the engine speed increases.

14. A control method of a hybrid vehicle,

the hybrid vehicle is provided with:

an internal combustion engine;

a motor generator; and

a power split mechanism having a plurality of gears that mesh with each other,

the control method comprises the following steps:

determining whether or not an air-fuel mixture is being stably combusted in a cylinder of an internal combustion engine while the internal combustion engine is operating; and

when it is determined that the air-fuel mixture is being stably combusted in the cylinder, a depression process is executed, the depression process being a process of causing the motor generator to output a torque in a direction in which a load applied to the internal combustion engine becomes large, and when it is not determined that the air-fuel mixture is being stably combusted, the depression process is not executed.