CN111911328A

CN111911328A - Control device and control method for internal combustion engine

Info

Publication number: CN111911328A
Application number: CN202010363971.8A
Authority: CN
Inventors: 安藤大吾; 水野仁; 林宪示
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 2019-05-07
Filing date: 2020-04-30
Publication date: 2020-11-10
Anticipated expiration: 2040-04-30
Also published as: CN111911328B; JP2020183719A; JP7159969B2

Abstract

A control device and a control method for an internal combustion engine are provided. In the retard amount increase process, when the temperature of the cooling water of the internal combustion engine is equal to or higher than a predetermined water temperature threshold, the retard amount of the ignition timing calculated by the knock control is increased by the retard correction amount. The delay correction amount is calculated based on the cooling water temperature. In the delay amount increasing process, the delay correction amount calculated during a period from the start of the automatic start of the intermittent operation control until the elapse of the predetermined period is made larger than the delay correction amount calculated after the elapse of the predetermined period from the start of the automatic start.

Description

Control device and control method for internal combustion engine

Technical Field

The present disclosure relates to a control device and a control method for an internal combustion engine.

Background

There is known a technique of suppressing occurrence of knocking (knocking) by retard-correcting the ignition timing of the internal combustion engine (for example, japanese patent laid-open No. 2009-228571).

Knocking is likely to occur when the cooling water temperature of the internal combustion engine is high, when the intake air amount of the internal combustion engine increases and the rate of change of the intake air amount is large. Therefore, when the cooling water temperature of the internal combustion engine detected by the water temperature sensor is equal to or higher than a predetermined water temperature threshold value, the delay amount increasing process is executed when the rate of change of the intake air amount with respect to the intake air amount of the internal combustion engine detected by the air amount sensor is equal to or higher than a predetermined rate of change threshold value. In the retard amount increase process, the retard amount of the ignition timing calculated by the knock control is increased and corrected. Thus, it is considered that the occurrence of knocking can be more appropriately suppressed.

Here, in an internal combustion engine that executes automatic stop and automatic start when a predetermined condition is satisfied, it is conceivable to execute the above-described delay amount increasing process. However, even so, knocking may occur at the start of the automatic start.

Disclosure of Invention

Examples of the present disclosure are described below.

Example 1 a control device for an internal combustion engine is configured to execute intermittent operation control for executing automatic stop and automatic start of the internal combustion engine and knock control for suppressing occurrence of knocking by adjusting ignition timing of the internal combustion engine. The control device is configured to execute a retard amount increase process of increasing and correcting a retard amount of the ignition timing by a retard correction amount calculated by the knock control when a cooling water temperature of the internal combustion engine is equal to or higher than a predetermined water temperature threshold value, the cooling water temperature being detected by a water temperature sensor, the retard correction amount being calculated based on the cooling water temperature, and the retard amount increase process of executing a process of making the retard correction amount calculated during a period from a start of the automatic start to a lapse of a predetermined period more than the retard correction amount calculated after the lapse of the predetermined period from the start of the automatic start.

According to the above configuration, in a situation where the detected value of the cooling water temperature is equal to or higher than the predetermined water temperature threshold value and knocking is likely to occur, the retard amount of the ignition timing calculated by the knock control is corrected to be increased by the retard correction amount calculated based on the cooling water temperature detected by the water temperature sensor, and thereby occurrence of knocking can be suppressed.

Here, during the automatic stop, the circulation of the cooling water is stopped. Therefore, it is difficult for the water temperature sensor to detect the actual temperature of the cooling water in the internal combustion engine. Therefore, a deviation is likely to occur between the actual temperature of the cooling water in the internal combustion engine and the temperature detected by the water temperature sensor in a short time after the start of the automatic start. As described above, the actual temperature of the cooling water in the internal combustion engine is hardly reflected on the detection value of the water temperature sensor for a short time after the start of the automatic start. This reduces the accuracy of the sensor detection value with respect to the actual temperature of the cooling water in the internal combustion engine. Therefore, even if the retard amount increasing process is executed, an appropriate value cannot be calculated as the retard correction amount, and as a result, knocking may occur.

In this regard, in the above configuration, the retard correction amount is increased as compared with other cases until a predetermined period of time elapses after the start of the automatic start, that is, in a case where knocking is likely to occur after the start of the automatic start. Therefore, occurrence of knocking at the time of starting the automatic start can be suppressed.

Example 2 in the control device of example 1, the retard amount increasing process may be a process of acquiring an amount of deposits (deposits) accumulated in a combustion chamber of the internal combustion engine, and a process of increasing the retard correction amount as the acquired amount of deposits increases.

According to the above configuration, the retard correction amount is increased as the amount of deposits accumulated in the combustion chamber is increased, that is, as knocking is more likely to occur. Therefore, for example, even if the amount of deposits is different, occurrence of knocking can be appropriately suppressed.

Example 3 in the control device of the above example 1 or 2, the internal combustion engine may be provided with a cooling device having a pump for circulating cooling water of the internal combustion engine, and the control device may be configured to execute a flow rate increasing process for increasing a flow rate of the cooling water discharged from the pump after the start of the automatic start as the operation stop time of the internal combustion engine before the automatic start becomes longer.

Example 4 a control device for an internal combustion engine, the control device being configured to execute intermittent operation control for executing automatic stop and automatic start of the internal combustion engine and knock control for suppressing occurrence of knocking by adjusting an ignition timing of the internal combustion engine. The control device is configured to execute a retard amount increase process of increasing and correcting a retard amount of an ignition timing, which is detected by a water temperature sensor, when a temperature of cooling water of the internal combustion engine is equal to or higher than a predetermined water temperature threshold value, the retard amount being calculated by the knock control, and a water temperature threshold value setting process of setting the water temperature threshold value set in a period from a start of the automatic start until a predetermined period elapses, to a value different from the water temperature threshold value set after the predetermined period elapses from the start of the automatic start.

According to the above configuration, the retard amount increase process is executed in a situation where the detected value of the cooling water temperature is equal to or higher than the predetermined water temperature threshold value and knocking is likely to occur. In the retard amount increase process, the retard amount of the ignition timing calculated by the knock control is increased. This can suppress occurrence of knocking.

Here, during the automatic stop, the circulation of the cooling water is stopped. Therefore, it is difficult for the water temperature sensor to detect the actual temperature of the cooling water in the internal combustion engine. Therefore, a deviation is likely to occur between the actual temperature of the cooling water in the internal combustion engine and the temperature detected by the water temperature sensor in a short time after the start of the automatic start. As described above, the actual temperature of the cooling water in the internal combustion engine is hardly reflected on the detection value of the water temperature sensor for a short time after the start of the automatic start. Therefore, the accuracy of the sensor detection value with respect to the actual temperature of the cooling water in the internal combustion engine is lowered. Therefore, even if the cooling water temperature detected by the water temperature sensor is compared with the water temperature threshold value, it may not be possible to appropriately determine that knocking is likely to occur. As a result, knocking may occur due to the non-execution of the above-described retardation amount increasing process.

In this regard, in the above configuration, the water temperature threshold set during a period from the start of the automatic start to the elapse of the predetermined period, that is, the water temperature threshold set in a situation where knocking is likely to occur after the start of the automatic start, is set to a value different from the water temperature threshold set after the elapse of the predetermined period from the start of the automatic start. Therefore, in a situation where knocking is likely to occur after the start of automatic start, the determination of a situation where knocking is likely to occur can be changed to a water temperature threshold value that is more likely to be determined as being true, as compared to other situations. Thereby, the delay amount increasing process is appropriately performed. Therefore, occurrence of knocking at the time of starting the automatic start can be suppressed.

Example 5 in the control device of example 4, the water temperature threshold value setting process may acquire an amount of deposits accumulated in a combustion chamber of the internal combustion engine, and execute a process of setting the water temperature threshold value to a lower value as the acquired amount of deposits increases.

According to the above configuration, the water temperature threshold value is set to a lower value as the amount of deposits accumulated in the combustion chamber increases, that is, as knocking is more likely to occur. Therefore, the delay amount increasing process is executed even at a low cooling water temperature. Thereby, even in the case where knocking is likely to occur due to a large amount of deposits, for example, occurrence of knocking can be appropriately suppressed.

Example 6 in the control device of the above example 4 or 5, the internal combustion engine may be provided with a cooling device having a pump for circulating cooling water of the internal combustion engine, and the control device may be configured to execute a flow rate increasing process for increasing a flow rate of the cooling water discharged from the pump after the start of the automatic start as the operation stop time of the internal combustion engine before the automatic start becomes longer.

According to the above configuration, the flow rate of the cooling water discharged from the pump increases as the operation stop time of the internal combustion engine is longer, that is, as the deviation between the actual temperature of the cooling water in the internal combustion engine and the temperature detected by the water temperature sensor is larger. Therefore, the deviation between the actual temperature of the cooling water and the temperature detected by the water temperature sensor can be quickly improved. Therefore, the period in which knocking is likely to occur after the start of automatic start can be shortened.

Example 7 is a control device for an internal combustion engine, the control device being configured to execute intermittent operation control for executing automatic stop and automatic start of the internal combustion engine, and knock control for suppressing occurrence of knocking by adjusting an ignition timing of the internal combustion engine. The control device is configured to execute a retard amount increase process of increasing and correcting a retard amount of an ignition timing, which is detected by an air amount sensor, when a change rate of an intake air amount when an intake air amount of the internal combustion engine is increased is equal to or greater than a predetermined change rate threshold value, the retard amount being calculated by the knock control, and a change rate threshold value setting process of setting the change rate threshold value, which is set in a period from a start of the automatic start until a predetermined period elapses, to a value different from the change rate threshold value, which is set after the predetermined period elapses from the start of the automatic start.

According to the above configuration, the retard amount increasing process is executed in a situation where the change rate of the detected intake air amount is equal to or greater than the predetermined change rate threshold value and knocking is likely to occur. In the retard amount increase process, the retard amount of the ignition timing calculated by the knock control is increased. This can suppress occurrence of knocking.

Here, during the automatic stop, the pressure in the intake passage of the internal combustion engine is returned to the atmospheric pressure. Therefore, the transient change rate of the air taken into the combustion chamber becomes large in a short time after the start of the automatic start, and therefore, a response delay of the air quantity sensor or the like is likely to occur. Further, immediately after the start of the automatic start, air remaining in the intake passage downstream of the throttle valve of the internal combustion engine flows through the intake passage upstream of the throttle valve after the air is drawn into the combustion chamber. For this reason, a deviation is likely to occur between the detection value of the air amount sensor provided in the intake passage upstream of the throttle valve and the actual intake air amount taken into the combustion chamber in a short time after the start of the automatic start. In this way, the actual amount of intake air taken into the combustion chamber is less likely to be reflected in the detection value of the air amount sensor within a short period of time after the start of the automatic start. This reduces the accuracy of the sensor detection value with respect to the actual intake air amount drawn into the combustion chamber. Therefore, even if the change rate obtained from the detection value of the air quantity sensor is compared with the change rate threshold value, it may not be possible to appropriately determine that knocking is likely to occur. As a result, knocking may occur due to the non-execution of the above-described retardation amount increasing process.

In this regard, in the above configuration, the change rate threshold set during a period from the start of the automatic start to the elapse of a predetermined period, that is, the change rate threshold set in a situation where knocking is likely to occur after the start of the automatic start, is set to the following value. That is, the change rate threshold value is set to a value different from the change rate threshold value set after a predetermined period has elapsed from the start of the automatic start. Therefore, in a situation where knocking is likely to occur after the start of automatic start, the determination of a situation where knocking is likely to occur can be changed to a change rate threshold value that is more likely to be determined as yes, compared to other situations. Thereby, the delay amount increasing process is appropriately performed. Therefore, occurrence of knocking at the time of starting the automatic start can be suppressed.

Example 8 in the control device of example 7, the change rate threshold value setting process may be a process of acquiring an amount of deposits accumulated in a combustion chamber of the internal combustion engine and setting the change rate threshold value to a smaller value as the acquired amount of deposits increases.

According to the above configuration, the change rate threshold value is set to a smaller value as the amount of deposits accumulated in the combustion chamber is larger, that is, as knocking is more likely to occur. Therefore, the delay amount increasing process is executed even at a small rate of change. Thereby, even in the case where the deposit amount is large so that knocking easily occurs, the occurrence of knocking can be appropriately suppressed.

Example 9: the present invention is embodied as a control method of an internal combustion engine for executing the various processes described in any one of the above-described examples 1 to 3.

Example 10: the present invention is embodied as a control method of an internal combustion engine for executing the various processes described in any one of the above-described embodiments 4 to 6.

Example 11: the present invention is embodied as a method for controlling an internal combustion engine that executes the various processes described in each of examples 7 and 8.

Example 12: the present invention is embodied as a non-transitory computer-readable storage medium storing a program for causing a processing device to execute various processes described in any one of examples 1 to 3.

Example 13: the present invention is embodied as a non-transitory computer-readable storage medium storing a program for causing a processing device to execute various processes described in any one of examples 4 to 6.

Example 14: the present invention is embodied as a non-transitory computer-readable storage medium storing a program for causing a processing device to execute the various processes described in each of examples 7 and 8.

Drawings

Fig. 1 is a schematic diagram showing a configuration of a hybrid vehicle including a control device for an internal combustion engine according to an embodiment of the present disclosure.

Fig. 2 is a schematic diagram showing the configuration of the cooling device provided in the internal combustion engine of the above-described embodiment in the hybrid vehicle of fig. 1.

Fig. 3 is a graph showing the relationship of the knock learning value and the deposit amount in the hybrid vehicle of fig. 1.

Fig. 4 is a flowchart showing steps of processing executed by the control device of the above embodiment in the hybrid vehicle of fig. 1.

Fig. 5 is a flowchart showing steps of a water temperature threshold value setting process executed by the control device of the above embodiment in the hybrid vehicle of fig. 1.

Fig. 6 is a flowchart showing the steps of the change rate threshold setting process executed by the control device of the above embodiment in the hybrid vehicle of fig. 1.

Fig. 7 is a flowchart showing the steps of the delay amount increase process executed by the control device of the above-described embodiment in the hybrid vehicle of fig. 1.

Fig. 8 is a graph showing the correspondence relationship between the cooling water temperature, the intake air temperature, and the deposit amount and the retard correction amount in the hybrid vehicle of fig. 1.

Fig. 9 is a flowchart showing the steps of the flow rate increase process executed by the control device of the above embodiment in the hybrid vehicle of fig. 1.

Fig. 10 is a graph showing the relationship between the operation stop time and the flow rate correction value in the hybrid vehicle of fig. 1.

Detailed Description

Hereinafter, an embodiment embodying the control device of the internal combustion engine of the present disclosure will be described with reference to fig. 1 to 10.

As shown in fig. 1, a vehicle 500 is a hybrid vehicle including an internal combustion engine 10 and an electric motor as prime movers. The vehicle 500 includes, as motors, a 1 st motor generator (hereinafter, referred to as a 1 st MG)71 as a 1 st electric motor and a 2 nd motor generator (hereinafter, referred to as a 2 nd MG)72 as a 2 nd electric motor.

The vehicle 500 includes the planetary gear mechanism 40. The planetary gear mechanism 40 is a mechanism that distributes the output of the internal combustion engine 10 to the rotor, which is the output shaft of the 1 st MG71, and the drive shaft 60 connected to the drive wheels 62. The planetary gear mechanism 40 includes a sun gear 41 and a ring gear 42 disposed coaxially with the sun gear 41. A plurality of pinion gears 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, and each pinion gear is supported by the carrier 44.

The crankshaft 34 of the internal combustion engine 10 is connected to the carrier 44, and the rotor of the 1MG71 is connected to the sun gear 41. A drive shaft 60 is connected to the ring gear 42, and the drive shaft 60 is connected to drive wheels 62 via a differential gear 61. The 1 st MG71 functions as a generator that generates electric power by using the output of the internal combustion engine, and functions as a starter (electric motor) for starting the internal combustion engine 10.

The rotor of the 2 nd MG72 is connected to the drive shaft 60 via the reduction mechanism 50. The 2 nd MG72 functions as an electric motor that generates driving force for the drive wheels 62, and functions as an electric generator that generates electric power by regenerative braking when the vehicle 500 decelerates.

The 1 st MG71 and the 2 nd MG72 exchange electric Power with the battery 78 via a PCU (Power Control Unit) 200. PCU200 includes a boost converter that boosts and outputs a dc voltage input from battery 78, an inverter that converts the dc voltage boosted by the boost converter into an ac voltage and outputs the ac voltage to MG71 and 72, and the like.

The internal combustion engine 10 includes an intake port 12 opened and closed by an intake valve 15, and an exhaust port 22 opened and closed by an exhaust valve 25. An intake passage 11 including a surge tank 13 is connected to the intake port 12, and a throttle 14 for adjusting an intake air amount is provided in the intake passage 11 at a position upstream of the surge tank 13. The opening degree of the throttle valve 14 is adjusted by an electric motor. An exhaust passage 21 is connected to the exhaust port 22.

Air is drawn into a combustion chamber 30 of the internal combustion engine 10 through an intake passage 11 and an intake port 12. The fuel injected into the intake port 12 from the fuel injection valve 31 is supplied to the combustion chamber 30. An air-fuel mixture is formed of the air and the fuel supplied to the combustion chamber 30 in this manner, and when the air-fuel mixture is ignited by the ignition plug 32, the air-fuel mixture is combusted and the piston 33 reciprocates. Then, the crankshaft 34, which is an output shaft of the internal combustion engine 10, rotates. The burned air-fuel mixture is discharged as exhaust gas from the combustion chamber 30 to the exhaust passage 21 through the exhaust port 22.

Fig. 2 shows a cooling device 300 of the internal combustion engine 10. As shown in fig. 2, a water jacket 10W through which cooling water flows is provided in a cylinder block 10S and a cylinder head 10H of the internal combustion engine 10. The wall surface of the intake port 12 and the wall surface of the top surface of the combustion chamber 30 are cooled by the water jacket 10W provided in the cylinder head 10H.

An outlet 19B of the water jacket 10W is provided in the cylinder head 10H, and a branch portion 350 is connected to the outlet 19B. The branch portion 350 branches the cooling water that has passed through the water jacket 10W of the internal combustion engine 10. A water temperature sensor 82 for detecting the temperature THW of the cooling water, which is the temperature of the cooling water, is provided near the outlet 19B.

An inlet 19A of the water jacket 10W is provided in the cylinder block 10S, and the inlet 19A and the branch portion 350 are connected to each other by the 1 st pipe 310. The 1 st pipe 310 is provided with a radiator 311(radiator) for cooling the cooling water by heat exchange with the outside air, a thermostat 312 (thermostat), and an electric water pump 313 (hereinafter, referred to as a pump) in this order from the upstream in the flow direction of the cooling water. When the thermostat 312 is opened, the cooling water that has passed through the water jacket 10W is returned to the water jacket 10W via the branch portion 350, the radiator 311, the thermostat 312, and the pump 313. When the thermostat 312 is closed, the circulation of the cooling water in the 1 st pipe 310 is stopped.

The branch portion 350 and the pump 313 are connected by the 2 nd pipe 320. The 2 nd pipe 320 is provided with a heat exchanger 321 (e.g., a heater core for heating air blown into the vehicle interior) for performing heat exchange with the cooling water. The cooling water that has passed through the water jacket 10W is returned to the water jacket 10W via the branch portion 350, the heat exchanger 321, and the pump 313. During the driving of the pump 313, the cooling water in the 2 nd pipe 320 circulates regardless of the open/close state of the thermostat 312.

As shown in fig. 1, control of the internal combustion engine 10, control of the 1 st MG71 and control of the 2 nd MG72 performed via the PCU200, and the like are executed by the control device 100 mounted on the vehicle 500.

The control device 100 includes a central processing unit (hereinafter, referred to as a CPU)110 and a memory 120 in which control programs and data are stored. Various controls are executed by the CPU110 executing programs stored in the memory 120. Although not shown, control device 100 is configured by a plurality of control units such as a control unit of internal combustion engine 10 and a control unit of PCU 200.

A crank angle sensor 80 that detects the rotation angle of the crankshaft 34, an air flow meter 81 that is an air amount sensor that detects the intake air amount GA of the internal combustion engine 10 and is provided in the intake passage 11 upstream of the throttle valve 14, and the water temperature sensor 82 are connected to the control device 100. Further, to the control device 100, an intake air temperature sensor 83 that detects an intake air temperature THA that is the temperature of the intake air drawn into the combustion chamber 30, a knock sensor 84 that detects occurrence of knocking in the combustion chamber 30, a vehicle speed sensor 85 that detects a vehicle speed SP of the vehicle 500, and an accelerator position sensor 86 that detects an accelerator operation amount ACCP that is the operation amount of an accelerator pedal are connected. Output signals from the various sensors are input to the control device 100. Further, control device 100 calculates engine speed NE based on output signal Scr of crank angle sensor 80, and determines whether knocking occurred or not based on output signal KN of knock sensor 84. Further, the control device 100 calculates a charging rate (hereinafter referred to as SOC) of the battery 78.

The control device 100 grasps the engine operating state and the like based on the detection signals of the various sensors, and performs various engine controls such as fuel injection control of the fuel injection valve 31, ignition timing control of the ignition plug 32, opening degree control of the throttle valve 14, discharge flow rate control of the pump 313, and the like in accordance with the grasped engine operating state.

The control device 100 calculates a target flow rate Ft of the pump 313 so that the temperature of the cooling water becomes a predetermined target value. Then, the control device 100 controls the driving of the pump 313 so that the flow rate of the cooling water discharged from the pump 313 matches the target flow rate Ft. Further, the control device 100 stops the driving of the pump 313 during an automatic stop period described later.

Further, control device 100 performs knock control for suppressing occurrence of knocking by adjusting the ignition timing of internal combustion engine 10. In the present embodiment, the ignition timing is represented as an advance of the crank angle with respect to the compression top dead center of the cylinder to be ignited. An example of the knock control performed in the present embodiment will be described below.

In this knock control, control device 100 calculates final ignition timing AFIN based on the following expressions (1) to (3). And control device 100 sets the calculated final ignition timing AFIN as the actual ignition timing. The final ignition timing AFIN is a value calculated to be an ignition timing on the advance side as much as possible while suppressing occurrence of knocking.

AFIN＝ABASE-AKNK…(1)

AFIN: final ignition timing

AKNK: amount of delay

In equation (1), the base ignition timing ABASE is calculated based on the MBT ignition timing AMBT and the 1 st knock-limit ignition timing AKNOK 1. Specifically, the more retarded side of the MBT ignition timing AMBT and the 1 st knock limit ignition timing AKNOK1 is set as the base ignition timing ABASE. Here, the MBT ignition timing AMBT is an ignition timing at which the maximum torque can be obtained under the current engine operating conditions, that is, the maximum torque ignition timing. The 1 st knock limit ignition timing AKNOK1 is an advance limit timing of the ignition timing that can converge the knock to within an allowable level under the optimum conditions assumed when a high octane (octane) value fuel having a high knock limit is used. The MBT ignition timing AMBT and the 1 st knock-limit ignition timing AKNOK1 are calculated and set based on the current engine speed NE, the engine load factor KL, and the like.

The delay amount AKNK in the formula (1) is a value obtained from the following formula (2). As the value of the retard amount AKNK increases, the final ignition timing AFIN becomes more retarded, and knocking becomes more difficult.

AKNK＝AKMAX-AGKNK+AKCS…(2)

AKNK: amount of delay

AKMAX: maximum delay amount

AGKNK: knock learning value

AKCS: feedback correction value

In equation (2), the feedback correction value AKCS is a value for quickly correcting the final ignition timing AFIN in accordance with the presence or absence of occurrence of knocking. The value of feedback correction value AKCS is set according to the occurrence of knocking detected by knock sensor 84. Specifically, when the level of the detected knock is smaller than a predetermined determination value, that is, when it is determined that the knock converges to or less than a sufficient allowable level, the value of the feedback correction value AKCS gradually decreases. When the level of the detected knocking is equal to or higher than the determination value, the value of the feedback correction value AKCS is increased by a predetermined value. When the value of the feedback correction value AKCS is negative, the value of the retard amount AKNK decreases, and the final ignition timing AFIN obtained by the above equation (1) is corrected to the advance side timing. On the other hand, when the value of the feedback correction value AKCS is positive, the value of the retard amount AKNK increases, and the final ignition timing AFIN obtained by the above equation (1) is corrected to a retard side timing.

In equation (2), the knock learning value AGKNK is a value updated when the absolute value of the feedback correction value AKCS increases to a certain extent. The knock learning value AGKNK is a value for suppressing an excessive increase in the absolute value of the feedback correction value AKCS. That is, the knock learning value AGKNK is updated as follows: when a state where the absolute value of the feedback correction value AKCS is larger than the predetermined value a (| AKCS | > a) continues for a predetermined time or more, the absolute value of the feedback correction value AKCS is reduced.

More specifically, when a state (AKCS > a) in which the feedback correction value AKCS is a positive value and the absolute value of the feedback correction value AKCS is larger than the predetermined value a continues, that is, when knocking is likely to occur, the predetermined value B of the positive value is subtracted from the value of the knock learning value AGKNK. At the same time, the predetermined value B is also subtracted from the value of the feedback correction value AKCS. Thus, the absolute value of the feedback correction value AKCS after the subtraction becomes equal to or smaller than the predetermined value a. Note that the knock learning value AGKNK and the feedback correction value AKCS are both updated using the same value (predetermined value B). Therefore, even if the predetermined value B is subtracted from the feedback correction value AKCS, the value of the final ignition timing AFIN does not change from the value of the final ignition timing AFIN before the predetermined value B is subtracted from the feedback correction value AKCS, but is maintained at the same value.

On the other hand, when a state (AKCS < -a) in which the feedback correction value AKCS is negative and the absolute value of the feedback correction value AKCS is larger than the predetermined value a continues, that is, when knocking is unlikely to occur, the predetermined value B is added to each of the value of the knock learning value AGKNK and the value of the feedback correction value AKCS. Thus, the absolute value of the feedback correction value AKCS after addition becomes equal to or smaller than the predetermined value a. Note that the knock learning value AGKNK and the feedback correction value AKCS are both updated using the same value (predetermined value B). Therefore, even if the predetermined value B is added to the feedback correction value AKCS, the value of the final ignition timing AFIN does not change from the value of the final ignition timing AFIN before the predetermined value B is added to the feedback correction value AKCS, but is maintained at the same value.

The maximum delay amount AKMAX in equation (2) is obtained from equation (3) below.

AKMAX＝ABASE-AKMF…(3)

AKMAX: maximum delay amount

ABASE: base ignition timing

AKMF: latest ignition timing

In equation (3), the latest ignition timing AKMF is an advance limit timing of the ignition timing that can converge the knock within the allowable level even under the assumed worst condition when the low octane fuel having a low knock limit is used. The latest ignition timing AKMF is set based on the current engine speed NE, the engine load factor KL, and the like.

Further, the control device 100 calculates the deposit amount DP, which is the amount of deposits adhering to the combustion chamber 30. Such calculation of the deposit amount DP can be appropriately performed. For example, in the present embodiment, the deposit amount DP is calculated as follows.

As shown in fig. 3, as the deposit amount DP of the combustion chamber 30 becomes larger, knocking becomes more likely to occur. Therefore, the value of the knock learning value AGKNK updated in the above-described embodiment becomes smaller. Therefore, the control device 100 executes the process of calculating the deposit amount DP based on the value of the knock learning value AGKNK such that the smaller the value of the knock learning value AGKNK, the larger the value of the deposit amount DP.

Further, control device 100 calculates a vehicle required output, which is a required value of the driving force of vehicle 500, based on accelerator operation amount ACCP, vehicle speed SP, and the like. Further, the control device 100 calculates an engine required torque TE, which is a required value of the output torque of the internal combustion engine 10, a 1MG required torque TM1, which is a required value of the power running torque or the regenerative torque of the 1MG71, and a 2MG required torque TM2, which is a required value of the power running torque or the regenerative torque of the 2MG72, respectively, based on the vehicle required output, the SOC, and the like. The control device 100 performs output control of the internal combustion engine 10 based on the engine required torque TE, and performs torque control of the 1MG71 and the 2MG72 based on the 1MG required torque TM1 and the 2MG required torque TM 2. Thereby, torque control required for traveling of vehicle 500 is performed.

Further, when the engine request torque TE is "0" and the condition that the operation of the internal combustion engine 10 can be stopped is satisfied, the control device 100 automatically stops the operation of the internal combustion engine 10. When the engine required torque TE exceeds "0" and the start condition of the internal combustion engine 10 whose operation has been stopped is satisfied, the control device 100 performs automatic start of the internal combustion engine 10 whose operation has been stopped. In this manner, the control device 100 performs intermittent operation control for executing automatic stop and automatic start of the internal combustion engine 10.

When the cooling water temperature of the internal combustion engine 10 is high, and when the rate of change of the intake air amount when the intake air amount of the internal combustion engine 10 increases is large, knocking is likely to occur. Therefore, control device 100 suppresses the occurrence of such knocking by executing the processing shown in fig. 4. The series of processing shown in fig. 4 is realized by the CPU110 executing a program stored in the memory 120 of the control device 100 every predetermined cycle. In the following, the step number is represented by a numeral denoted by "S" at the head.

When the processing shown in fig. 4 is started, the control device 100 acquires the water temperature threshold value THWref and the change rate threshold value GARref (S100). The water temperature threshold value THWref and the change rate threshold value GARref are calculated by a water temperature threshold value setting process and a change rate threshold value setting process, which will be described later. When the cooling water temperature THW detected by the water temperature sensor 82 is equal to or higher than the water temperature threshold value THWref, it is determined that the current temperature state of the cooling water is a state in which knocking is likely to occur. When the intake air change rate GAR, which is the rate of change of the intake air amount GA when the intake air amount GA detected by the airflow meter 81 increases, is equal to or greater than the change rate threshold GARref, it is determined that the current intake air state is a state in which knocking is likely to occur.

Next, the controller 100 determines whether or not the current coolant temperature THW is equal to or higher than the acquired water temperature threshold THWref (S110). If it is determined that the cooling water temperature THW is equal to or higher than the water temperature threshold value THWref (YES in S110), the control device 100 is in a state in which knocking is likely to occur, and therefore executes the process of S130. In the processing of S130, retard amount increasing processing for increasing and correcting the retard amount AKNK calculated by the knock control by a retard correction amount calculated based on the cooling water temperature THW or the like is executed. This can suppress occurrence of knocking even in a situation where knocking is likely to occur. Then, control device 100 once ends this process.

If it is determined in S110 that the coolant temperature THW is less than the water temperature threshold THWref (NO in S110), the control device 100 determines whether or not the current intake air change rate GAR is equal to or greater than the acquired change rate threshold GARref (S120). The intake air change rate GAR is the amount of change per unit time of the intake air amount GA, and the value of the intake air change rate GAR becomes a positive value when the intake air amount GA increases, while the value of the intake air change rate GAR becomes a negative value when the intake air amount GA decreases. In addition, the rate-of-change threshold GARref is set to a positive value.

If it is determined that the intake air change rate GAR is equal to or greater than the change rate threshold GARref (S120: yes), that is, if the intake air change rate GAR when the intake air amount GA increases is equal to the change rate threshold GARref, knocking is likely to occur, and therefore the control device 100 executes the process of S130. That is, even in a situation where knocking is likely to occur, by executing the above-described retardation amount increasing process, occurrence of knocking can be suppressed. Then, control device 100 once ends this process.

If it is determined in S120 that the intake air change rate GAR is smaller than the change rate threshold GARref (no in S120), it can be determined that the current temperature state of the cooling water and the current intake air state are both states in which knocking is unlikely to occur. Therefore, the control device 100 does not execute the delay amount increasing process and once ends the process.

By executing such a series of processing shown in fig. 4, occurrence of knocking can be appropriately suppressed even when the intake air change rate GAR is large when the cooling water temperature THW of the internal combustion engine 10 is high.

Here, during the automatic stop of the internal combustion engine 10, the circulation of the cooling water is stopped. Therefore, it is difficult for the water temperature sensor 82 to detect the actual temperature of the cooling water in the internal combustion engine 10. Therefore, a deviation is likely to occur between the actual temperature of the cooling water in the internal combustion engine 10 and the temperature detected by the water temperature sensor 82 in a short time after the start of the automatic start. Hereinafter, such a temperature deviation is referred to as a water temperature deviation. As described above, the actual temperature of the cooling water in the internal combustion engine 10 is hardly reflected on the detection value of the water temperature sensor 82 in a short time after the start of the automatic start. That is, the accuracy of the sensor detection value with respect to the actual temperature of the cooling water in the internal combustion engine 10 is reduced. Therefore, even if the delay amount increasing process is executed, the delay correction amount set based on the cooling water temperature THW that is the detection value of the water temperature sensor 82 may not be an appropriate value corresponding to the actual temperature of the cooling water in the internal combustion engine 10. That is, knocking may occur.

Further, when the accuracy of the detection value of the water temperature sensor 82 with respect to the actual temperature of the cooling water in the internal combustion engine 10 is lowered in this manner, even if the cooling water temperature THW detected by the water temperature sensor 82 is compared with the water temperature threshold value THWref, it may be impossible to appropriately determine that knocking is likely to occur. As a result, knocking may occur due to the non-execution of the above-described retardation amount increasing process.

During the automatic stop, the pressure in the intake passage 11 and the intake port 12 of the internal combustion engine 10 is returned to the atmospheric pressure. Therefore, the transient change rate of the air taken into the combustion chamber 30 becomes large in a short time after the start of the automatic start, and therefore, a response delay or the like is likely to occur in the detection of the intake air amount by the air flow meter 81. Immediately after the start of the auto start, air remaining in the intake passage 11 downstream of the throttle valve 14 and in the intake port 12 is drawn into the combustion chamber 30, and then air flows in the intake passage 11 upstream of the throttle valve 14. For this reason, a deviation is likely to occur between the detection value of the airflow meter 81 provided in the intake passage 11 upstream of the throttle valve 14 and the actual amount of intake air taken into the combustion chamber 30 in a short time after the start of the automatic start. Hereinafter, such a variation in the intake air amount is referred to as an air amount variation. As described above, the actual amount of intake air taken into the combustion chamber 30 in a short time after the start of the automatic start is hardly reflected on the detection value of the airflow meter 81. That is, the accuracy of the sensor detection value with respect to the actual intake air amount drawn into the combustion chamber 30 is lowered. Therefore, even if the intake air change rate GAR obtained from the intake air amount GA, which is the detection value of the airflow meter 81, is compared with the change rate threshold GARref, it may not be possible to appropriately determine that knocking is likely to occur. As a result, knocking may occur due to the non-execution of the above-described retardation amount increasing process.

Therefore, in the present embodiment, the water temperature threshold value THWref and the change rate threshold value GARref are appropriately switched by executing each process described below. At the same time, the delay correction amount in the delay amount increasing process can be calculated appropriately. This suppresses occurrence of knocking at the start of the automatic start.

Hereinafter, such respective processes will be described with reference to fig. 5 to 8.

Fig. 5 shows the steps of the processing performed by the control device 100 to set the water temperature threshold value THWref. Further, a series of processing shown in fig. 5 is realized by the CPU110 executing a program stored in the memory 120 of the control device 100 every predetermined cycle.

After the water temperature threshold value setting process is started, control device 100 determines whether or not a predetermined period of time has elapsed from the start of automatic activation (S200). In S200, if a period required until the water temperature deviation after the start of the automatic start becomes a value within an allowable range for suppressing a decrease in detection accuracy of the water temperature sensor 82 with respect to the actual temperature of the cooling water in the internal combustion engine 10 elapses, the control device 100 determines that a predetermined period has elapsed from the start of the automatic start. The predetermined period can be set to an appropriate time by a preliminary experiment or the like. The predetermined period may be determined to have elapsed based on a fact that the rate of change in the detected value of the water temperature sensor 82 after the start of the automatic start is stabilized at or below a predetermined value.

When it is determined that the predetermined period of time has elapsed since the start of the automatic start (yes in S200), the control device 100 acquires the currently calculated deposit amount DP and calculates the 1 st correction coefficient Kw1 based on the acquired deposit amount DP (S210). The value of the 1 st correction coefficient Kw1 is greater than "0" and is in the range of "1" or less (0 < Kw 1. ltoreq.1). The value of the 1 st correction coefficient Kw1 is variably set based on the deposit amount DP such that the 1 st correction coefficient Kw1 becomes smaller as the deposit amount DP increases.

Next, the controller 100 sets a value obtained by multiplying the 1 st water temperature threshold value THWrefa by the 1 st correction coefficient Kw1 as the water temperature threshold value THWref (S220). The 1 st water temperature threshold value THWrefa is a water temperature threshold value THWref suitable for determining the ease of occurrence of knocking in a situation where the deposit amount DP is "0" and the above-described water temperature deviation becomes a value within the allowable range. The 1 st water temperature threshold value THWrefa is set to an appropriate value by a preliminary test or the like.

As described above, in S220, the water temperature threshold value THWref appropriate for the predetermined period of time after the start of the automatic start is set. Then, the control device 100 sets the delay amount setting flag FR to "0" (S230), and once ends the present process. The delay amount setting flag FR is a flag referred to in the delay amount increasing process described later, and when the value of the delay amount setting flag FR is set to "0", it indicates that it is determined that the predetermined period has elapsed from the start of the automatic start in the process of S200 or the process of S300 described later. When the value of the delay amount setting flag FR is set to "1", it indicates that it is determined in the above-described process of S200 or the process of S300 described later that the predetermined period of time has not elapsed from the start of the automatic start.

If it is determined in S200 that the predetermined period of time has not elapsed since the start of the automatic start (S200: no), that is, if the water temperature deviation after the start of the automatic start is a value outside the allowable range, control device 100 executes the process of S240. In S240, the control device 100 acquires the currently calculated deposit amount DP, and calculates the 2 nd correction coefficient Kw2 based on the acquired deposit amount DP. The value of the 2 nd correction coefficient Kw2 is also a value in the range of "1" or less which is larger than "0" (0 < Kw 2. ltoreq.1). The value of the 2 nd correction coefficient Kw2 is variably set based on the deposit amount DP so that the 2 nd correction coefficient Kw2 becomes smaller as the deposit amount DP increases.

Next, the controller 100 sets a value obtained by multiplying the 2 nd water temperature threshold value THWrefb by the 2 nd correction coefficient Kw2 as the water temperature threshold value THWref (S250). The 2 nd water temperature threshold value THWrefb is a water temperature threshold value THWref suitable for determining the ease of occurrence of knocking in a situation where the deposit amount DP is "0" and the above-described water temperature deviation becomes a value outside the allowable range. The 2 nd water temperature threshold value THWrefb is set to an appropriate value by a preliminary experiment or the like.

In the water temperature deviation in the period from the start of the automatic start to the elapse of the predetermined period, when the actual temperature of the cooling water in the internal combustion engine 10 is higher than the temperature detected by the water temperature sensor 82, the water temperature threshold value THWref is set to a lower temperature than when the water temperature deviation is within the allowable range, for example. This makes it possible to appropriately detect the ease of occurrence of knocking. Conversely, when the actual temperature of the cooling water in the internal combustion engine 10 is lower than the temperature detected by the water temperature sensor 82, the water temperature threshold value THWref is set to a higher temperature than when the water temperature deviation is within the allowable range, for example, with respect to the water temperature deviation in the period from the start of the automatic start to the elapse of the predetermined period. This makes it possible to appropriately detect the ease of occurrence of knocking.

Therefore, when the actual temperature of the cooling water in the internal combustion engine 10 is higher than the temperature detected by the water temperature sensor 82, the water temperature deviation in the period from the start of the automatic start to the elapse of the predetermined period is set to a temperature lower than the 1 st water temperature threshold value THWrefa as the 2 nd water temperature threshold value THWrefb. Conversely, when the actual temperature of the coolant in the internal combustion engine 10 is lower than the temperature detected by the water temperature sensor 82, the water temperature deviation between the time when the predetermined period elapses after the start of the automatic start is set to be higher than the 1 st water temperature threshold THWrefa as the 2 nd water temperature threshold THWrefb.

In this manner, in S250, the water temperature threshold value THWref appropriate for the period from the start of the automatic start to the elapse of the predetermined period is set. Then, the control device 100 sets the delay amount setting flag FR to "1" (S260), and once ends the present process.

Fig. 6 shows a procedure of processing performed by the control device 100 to set the change rate threshold value GARref. The series of processing shown in fig. 6 is also realized by the CPU110 executing a program stored in the memory 120 of the control device 100 every predetermined cycle.

When the rate of change threshold setting process is started, control device 100 determines whether or not a predetermined period of time has elapsed from the start of the automatic start (S300). In S300, if a period required until the deviation of the air amount after the start of the automatic start becomes a value within an allowable range for suppressing a decrease in the detection accuracy of the air flow meter 81 with respect to the actual intake air amount drawn into the combustion chamber 30 elapses, the control device 100 determines that a predetermined period has elapsed from the start of the automatic start. In addition, in such a predetermined period, an appropriate time can be set by a preliminary experiment or the like. The predetermined period may be determined to have elapsed based on the fact that the intake air change rate GAR obtained based on the detection value of the airflow meter 81 after the start of the automatic start is stabilized at or below a predetermined value.

When it is determined that the predetermined period of time has elapsed since the start of the automatic start (yes in S300), the control device 100 acquires the currently calculated deposit amount DP and calculates the 1 st correction coefficient Kr1 based on the acquired deposit amount DP (S310). The value of the 1 st correction coefficient Kr1 is greater than 0 and is in the range of 1 or less (0 < Kr 1. ltoreq.1). The value of the 1 st correction coefficient Kr1 is variably set based on the deposit amount DP such that the 1 st correction coefficient Kr1 becomes a smaller value as the deposit amount DP increases.

Next, the control device 100 sets a value obtained by multiplying the 1 st change rate threshold GARrefa by the 1 st correction coefficient Kr1 as a change rate threshold GARref (S320). The 1 st rate of change threshold GARrefa is a rate of change threshold GARref suitable for determining the ease of occurrence of knocking in a situation where the deposit amount DP is "0" and the above-described air amount deviation becomes a value within the allowable range. The 1 st rate of change threshold GARrefa is set to an appropriate value by a preliminary experiment or the like.

In this manner, in S320, the change rate threshold GARref suitable for the predetermined period of time after the start of the auto start is set. Then, the control device 100 sets the delay amount setting flag FR to "0" (S330), and once ends the present process.

If it is determined in S300 that the predetermined period of time has not elapsed since the start of the automatic start (S300: no), that is, if the air amount deviation after the start of the automatic start is a value outside the allowable range, the control device 100 executes the process of S340. In S340, the control device 100 obtains the currently calculated deposit amount DP, and calculates the 2 nd correction coefficient Kr2 based on the obtained deposit amount DP. The value of the 2 nd correction coefficient Kr2 is also a value within a range greater than "0" and equal to or less than "1" (0 < Kr2 ≦ 1). Also, the value of the 2 nd correction coefficient Kr2 is variably set based on the deposit amount DP such that the 2 nd correction coefficient Kr2 becomes a smaller value as the deposit amount DP increases.

Next, the control device 100 sets a value obtained by multiplying the 2 nd change rate threshold GARrefb by the 2 nd correction coefficient Kr2 as the change rate threshold GARref (S350). The 2 nd rate of change threshold GARrefb is a rate of change threshold GARref suitable for determining the ease of occurrence of knocking in a situation where the deposit amount DP is "0" and the above-described air amount deviation becomes a value outside the allowable range. The 2 nd rate of change threshold GARrefb is set to an appropriate value by a preliminary experiment or the like.

In addition, in the case where the actual amount of intake air drawn into the combustion chamber 30 is larger than the detection value of the airflow meter 81, the air amount deviation in the period from the start of the automatic start to the elapse of the predetermined period is set to a smaller value than, for example, the case where the air amount deviation is within the allowable range. This makes it possible to appropriately detect the ease of occurrence of knocking. Conversely, when the actual amount of intake air drawn into the combustion chamber 30 is smaller than the detection value of the airflow meter 81, the change rate threshold value GARref is set to a larger value than when the air amount deviation is within the allowable range, for example, with respect to the air amount deviation in the period from the start of the automatic start until the predetermined period elapses. This makes it possible to appropriately detect the ease of occurrence of knocking.

Therefore, when the actual amount of intake air drawn into the combustion chamber 30 is larger than the detection value of the airflow meter 81, the air amount deviation in the period from the start of the automatic start to the elapse of the predetermined period is set to a value smaller than the 1 st change rate threshold GARrefa as the 2 nd change rate threshold GARrefb. Conversely, when the actual amount of intake air drawn into the combustion chamber 30 is smaller than the detection value of the airflow meter 81, the air amount deviation in the period from the start of the automatic start to the elapse of the predetermined period is set to a value larger than the 1 st change rate threshold GARrefa as the 2 nd change rate threshold GARrefb.

In this manner, in S350, the change rate threshold GARref suitable for the period from the start of the auto start to the elapse of the predetermined period is set. Then, the control device 100 sets the delay amount setting flag FR to "1" (S360), and once ends the present process.

Fig. 7 shows a procedure of processing performed by the control device 100 to execute the delay amount increasing processing. The series of processing shown in fig. 7 is also realized by the CPU110 executing a program stored in the memory 120 of the control device 100 every predetermined cycle.

When the processing is started, the control device 100 determines whether or not the delay amount setting flag FR is "0" (S400). If it is determined that the retardation amount setting flag FR is "0" (yes in S400), that is, if the predetermined period of time has elapsed from the start of the automatic start and knocking due to the water temperature deviation and the air amount deviation is unlikely to occur, the control device 100 executes the process of S410.

In S410, the control device 100 calculates a 1 st retard correction amount RHa for increasing and correcting the retard amount AKNK based on the cooling water temperature THW, the intake air temperature THA, and the respective current values of the calculated deposit amount DP.

The 1 st retard correction amount RHa is a value for increasing and correcting the retard amount AKNK. The 1 st retard correction amount RHa is a value set when the retard amount increase process is executed in a situation where the water temperature deviation and the air amount deviation are within the allowable range.

As shown in fig. 8, the 1 st retard correction amount RHa is set to a value that becomes larger as the cooling water temperature THW becomes higher. This is because: since knocking is more likely to occur as the cooling water temperature THW increases, it is necessary to increase the retard correction amount for correcting the retard amount AKNK in order to suppress the occurrence of knocking due to the cooling water temperature. The 1 st retard correction amount RHa is set to a value that increases as the intake air temperature THA increases. This is because: since knocking is more likely to occur as the intake air temperature THA increases, a retard correction amount for correcting the retard amount AKNK needs to be increased in order to suppress the occurrence of knocking due to the intake air temperature. The 1 st retard correction amount RHa is set to have a larger value as the deposit amount DP increases. This is because: since knocking is more likely to occur as the deposit amount DP increases, it is necessary to increase the retard correction amount for correcting the retard amount AKNK in order to suppress the occurrence of knocking due to deposits.

When calculating the 1 st retard correction amount RHa in this manner, the control device 100 adds the 1 st retard correction amount RHa to the retard amount AKNK calculated in the knock control to thereby increase and correct the retard amount AKNK (S420). Then, this process is once ended.

On the other hand, if it is determined in S400 that the retardation setting flag FR is not "0" (S400: no), that is, if the retardation setting flag FR is "1" and the predetermined period of time has not yet elapsed since the start of automatic start, and knocking due to the water temperature deviation and the air amount deviation is likely to occur, the control device 100 executes the process of S430.

In S430, the control device 100 calculates a 2 nd retard correction amount RHb for increasing and correcting the retard amount AKNK based on the cooling water temperature THW, the intake air temperature THA, and the current values of the calculated deposit amount DP.

The 2 nd retard correction amount RHb is also a value for increasing and correcting the retard amount AKNK. The 2 nd retard correction amount RHb is a value set when the retard amount increase process is executed in a situation where the water temperature deviation and the air amount deviation are outside the allowable range.

As shown in fig. 8, the 2 nd retard correction amount RHb is set to a value that is larger as the cooling water temperature THW is higher, the intake air temperature THA is higher, or the deposit amount DP is larger, as the 1 st retard correction amount RHa is higher. However, even at the same cooling water temperature THW, the 2 nd retard correction amount RHb is set to a value larger than the 1 st retard correction amount RHa. Similarly, the 2 nd retard correction amount RHb is set to a value larger than the 1 st retard correction amount RHa even at the same intake air temperature THA. The 2 nd retard correction amount RHb is set to a value larger than the 1 st retard correction amount RHa even for the same deposit amount DP. Therefore, the value of the delay amount AKNK corrected by the 2 nd delay correction amount RHb is larger than the value of the delay amount AKNK corrected by the 1 st delay correction amount RHa.

When calculating the 2 nd retard correction amount RHb in this manner, the control device 100 adds the 2 nd retard correction amount RHb to the retard amount AKNK calculated in the knock control. Thereby, the delay amount AKNK is increased and corrected (S440). Then, this process is once ended.

Further, the control device 100 executes flow rate increasing processing for increasing the flow rate of the cooling water discharged from the pump 313.

Fig. 9 shows a procedure of processing performed by the control device 100 to execute the flow rate increase processing. The series of processes shown in fig. 9 is a process executed when the automatic start is started, and is realized by the CPU110 executing a program stored in the memory 120 of the control device 100.

When the present process is started, the control device 100 acquires the operation stop time TS of the internal combustion engine 10 before the present automatic start, and calculates the flow rate correction value FH based on the acquired operation stop time TS (S500). The flow rate correction value FH is a value obtained by increasing and correcting the target flow rate Ft of the pump 313.

As shown in fig. 10, the flow rate correction value FH is set to have a value that increases as the operation stop time TS increases.

When the flow rate correction value FH is calculated in this manner, the control device 100 adds the flow rate correction value FH to the target flow rate Ft to increase and correct the target flow rate Ft (S510). When the target flow rate Ft is corrected to be increased in this manner, the flow rate of the cooling water discharged from the pump 313 becomes larger than that before the increase correction.

Next, control device 100 determines whether or not a predetermined period of time has elapsed since the start of the automatic start (S520). In the present embodiment, the process of S520 is the same as the process of S200 described above, but the predetermined period in S520 and the predetermined period in S200 may be different from each other.

Control device 100 repeatedly executes the process of S520 until it is determined that the predetermined period has elapsed since the start of the automatic start.

If it is determined in S520 that the predetermined period has elapsed since the start of the automatic start (S520: yes), the control device 100 resets the flow rate correction value FH to set the value of the flow rate correction value FH to "0" (S530). When the flow rate correction value FH is reset in this manner, the increase correction of the target flow rate Ft is suspended. Then, control device 100 ends the present process.

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

(1) In the delay amount increasing process shown in fig. 7, if it is determined no in S400, the 2 nd delay correction amount RHb larger than the 1 st delay correction amount RHa is set (S430). Therefore, in a situation where knocking is likely to occur after the start of automatic start, that is, after the start of automatic start, the amount of retard correction for increasing the retard amount AKNK increases as compared with other situations until a predetermined period elapses. Therefore, occurrence of knocking at the time of starting the automatic start can be suppressed.

(2) As shown in fig. 8, the 1 st retard correction amount RHa and the 2 nd retard correction amount RHb are set to have larger values as the deposit amount DP increases. Therefore, even if the deposit amount is different, occurrence of knocking can be appropriately suppressed.

(3) Similarly, the 1 st retard correction amount RHa and the 2 nd retard correction amount RHb are set to have values that increase as the cooling water temperature THW increases or as the intake air temperature THA increases. Therefore, even if the cooling water temperature THW and the intake air temperature THA are different, occurrence of knocking can be appropriately suppressed.

(4) In the water temperature threshold value setting process shown in fig. 5, if it is determined yes in S200, a value obtained by correcting the 1 st water temperature threshold value THWrefa is set as the water temperature threshold value THWref (S220). On the other hand, if it is determined no in S200, a value obtained by correcting the 2 nd water temperature threshold value THWrefb different from the 1 st water temperature threshold value THWrefa is set as the water temperature threshold value THWref (S250).

As described above, the water temperature threshold value THWref set in the period from the start of the automatic start to the elapse of the predetermined period, that is, the water temperature threshold value THWref set in a situation where knocking is likely to occur after the start of the automatic start has a value based on the 2 nd water temperature threshold value THWrefb. On the other hand, the water temperature threshold value THWref set after a predetermined period has elapsed since the start of the automatic start-up is a value based on the 1 st water temperature threshold value THWrefa. That is, the water temperature threshold value THWref is set to different values before and after the predetermined period elapses. Therefore, in a situation where knocking is likely to occur after the start of automatic start, the water temperature threshold value THWref can be changed to a water temperature threshold value THWref that is more likely to be determined as being the situation where knocking is likely to occur than in other situations. Thereby, the delay amount increasing process is appropriately performed. Therefore, the occurrence of knocking at the time of starting the automatic start can also be suppressed.

(5) In the water temperature threshold value setting process shown in fig. 5, the 1 st correction coefficient Kw1 and the 2 nd correction coefficient Kw2 are set so as to have smaller values as the deposit amount DP increases (S210 and S240). Therefore, the water temperature threshold value THWref set in the processing of S220 and the processing of S250 becomes a lower value as the amount of deposits accumulated in the combustion chamber 30 is larger and knocking is more likely to occur. Therefore, the delay amount increase process is executed even at a low cooling water temperature THW. Thus, even when the amount of deposits is large and knocking is likely to occur, the occurrence of knocking can be appropriately suppressed.

(6) In the flow rate increasing process shown in fig. 9, the increase correction of the target flow rate Ft based on the flow rate correction value FH is performed until the flow rate correction value FH is reset after a predetermined period of time has elapsed from the start of the automatic start. As shown in fig. 10, the flow rate correction value FH is set to have a value that increases as the operation stop time TS of the internal combustion engine 10 increases. Therefore, the operation stop time TS is long, and the larger the deviation between the actual temperature of the cooling water in the internal combustion engine 10 and the temperature detected by the water temperature sensor 82 is, the larger the flow rate of the cooling water discharged from the pump 313 becomes. That is, the deviation between the actual temperature of the cooling water and the temperature detected by the water temperature sensor 82 can be improved quickly. Therefore, the period in which knocking is likely to occur after the start of automatic start can be shortened.

(7) In the change rate threshold value setting process shown in fig. 6, if it is determined yes in S300, the value obtained by correcting the 1 st change rate threshold value GARrefa is set as the change rate threshold value GARref (S320). On the other hand, if it is determined no in S300, a value obtained by correcting the 2 nd rate-of-change threshold GARrefb different from the 1 st rate-of-change threshold GARrefa is set as the rate-of-change threshold GARref (S350).

In this manner, the change rate threshold value GARref set during a period from the start of the automatic start to the elapse of a predetermined period, that is, the change rate threshold value GARref set in a situation where knocking is likely to occur after the start of the automatic start, has a value based on the 2 nd change rate threshold value GARrefb. On the other hand, the change rate threshold GARref set after a predetermined period has elapsed since the start of the automatic start is a value based on the 1 st change rate threshold GARrefa. That is, the change rate threshold GARref is set to different values before and after the predetermined period elapses. Therefore, in a situation where knocking is likely to occur after the start of the automatic start, the determination of a situation where knocking is likely to occur can be changed to the change rate threshold value GARref that is more likely to be determined as yes, compared to other situations. Thereby, the delay amount increasing process is appropriately performed. Therefore, the occurrence of knocking at the time of starting the automatic start can also be suppressed.

(8) In the change rate threshold value setting process shown in fig. 6, the 1 st correction coefficient Kr1 and the 2 nd correction coefficient Kr2 are set so as to have smaller values as the deposit amount DP increases (S310 and S340). Therefore, the smaller the change rate threshold GARref set in the processing of S320 and the processing of S350, the more the knocking is likely to occur due to the larger amount of deposits accumulated in the combustion chamber 30. Therefore, the retard amount increase process is executed even with a small intake air change rate GAR. Thus, even in the case where the deposit amount is large and knocking is likely to occur, the occurrence of knocking can be appropriately suppressed.

The above embodiment can be modified and implemented as follows. The above-described embodiment and the following modifications can be implemented in combination with each other within a range not technically contradictory.

In the above embodiment, the water temperature threshold value THWref is set to different values before and after the predetermined period has elapsed from the start of the automatic start-up. At the same time, a different value is set for the change rate threshold GARref. The delay correction amount set by the delay amount increasing process is also set to different values before and after the predetermined period elapses.

Note that the processing for making the water temperature threshold value THWref and the change rate threshold value GARref different before and after the predetermined period elapses may be omitted. That is, only the processing of setting the delay correction amount set by the delay amount increasing processing to different values before and after the predetermined period has elapsed may be executed. In this case, for example, the water temperature threshold value THWref is set by the respective processes of S210 and S220 shown in fig. 5. The change rate threshold GARref may be set by the respective processes of S310 and S320 shown in fig. 6. In such a modification, the operational effects other than the above (4) and (7) can be obtained.

In the above embodiment, the water temperature threshold value THWref is set to different values before and after the predetermined period has elapsed from the start of the automatic start-up. Also, the change rate threshold GARref is set to a different value. Further, the different threshold values before and after the predetermined period of time has elapsed from the start of the automatic start may be only the water temperature threshold value THWref. That is, the change rate threshold GARref may be set by the respective processes of S310 and S320 shown in fig. 6. Even in this case, an action and effect other than (7) above can be obtained. Further, the threshold value that is different before and after the predetermined period of time has elapsed from the start of the automatic start may be set to only the change rate threshold value GARref. That is, the water temperature threshold value THWref may be set by the respective processes of S210 and S220 shown in fig. 5. Even in this case, the operational effects other than (4) above can be obtained.

In the processing shown in fig. 4, as the condition for executing the delay amount increasing processing, a condition is set such that "the cooling water temperature THW is equal to or higher than the water temperature threshold THWref" or "the intake air change rate GAR is equal to or higher than the change rate threshold GARref". Not limited to this, any of the above conditions may be omitted.

Note that, in the case where the condition "the cooling water temperature THW is equal to or higher than the water temperature threshold value THWref" is omitted, the water temperature threshold value setting process shown in fig. 5 is also omitted. In addition, when the condition that "the intake air change rate GAR is equal to or greater than the change rate threshold GARref" is omitted, the change rate threshold setting process shown in fig. 6 is also omitted.

In addition, even when the temperature of the air drawn into the combustion chamber 30 is high, knocking is likely to occur. Therefore, the condition that the intake air temperature THA is equal to OR higher than the predetermined intake air temperature threshold value may be added as one of OR conditions for executing the delay amount increasing process. That is, the above-described retardation amount increasing process may also be executed in a case where the condition regarding the intake air temperature THA is satisfied.

In the water temperature threshold value setting process shown in fig. 5, in order to correct the water temperature threshold value according to the deposit amount DP, a correction coefficient is calculated based on the deposit amount DP. The correction of the water temperature threshold value according to the deposit amount DP may be performed by another method. For example, the value of the 1 st water temperature threshold value THWrefa and the value of the 2 nd water temperature threshold value THWrefb are variably set based on the deposit amount DP such that the value of the 1 st water temperature threshold value THWrefa and the value of the 2 nd water temperature threshold value THWrefb are smaller as the deposit amount DP is larger. The set value of the 1 st water temperature threshold value THWrefa and the set value of the 2 nd water temperature threshold value THWrefb may be set as the water temperature threshold value THWref.

In the water temperature threshold value setting process, the correction of the water temperature threshold value according to the deposit amount DP may be omitted.

In the change rate threshold value setting processing shown in fig. 6, in order to correct the change rate threshold value in accordance with the deposit amount DP, a correction coefficient is calculated based on the deposit amount DP. The change rate threshold may be corrected according to the deposit amount DP by another method. For example, the values of the 1 st rate-of-change threshold value GARrefa and the 2 nd rate-of-change threshold value GARrefb are variably set based on the deposit amount DP such that the more the deposit amount DP, the smaller the values of the 1 st rate-of-change threshold value GARrefa and the 2 nd rate-of-change threshold value GARrefb. The set value of the 1 st change rate threshold GARrefa and the set value of the 2 nd change rate threshold GARrefb may be set as the change rate threshold GARref.

In the change rate threshold value setting process, the correction of the change rate threshold value according to the deposit amount DP may be omitted.

In the retard amount increase processing shown in fig. 7, the 1 st retard correction amount RHa and the 2 nd retard correction amount RHb are calculated based on the cooling water temperature THW, the intake air temperature THA, and the deposit amount. Not limited to this, the 1 st retard correction amount RHa and the 2 nd retard correction amount RHb may be calculated based on at least the cooling water temperature THW.

In the delay amount increasing process shown in fig. 7, when it is determined in S400 that the delay amount is not increased, the 2 nd delay correction amount RHb larger than the 1 st delay correction amount RHa is set as a value for increasing and correcting the delay amount AKNK. The respective processes of S400, S430, and S440 shown in fig. 7, the respective processes of S230 and S260 shown in fig. 5, and the respective processes of S330 and S360 shown in fig. 6 may be omitted. Thus, the delay correction amount set when the delay amount increasing process is executed may always be the 1 st delay correction amount RHa. Even in this case, the operational effects other than (1) above can be obtained.

In the flow rate increasing process shown in fig. 9, the flow rate of the cooling water discharged from the pump 313 is increased by increasing and correcting the target flow rate Ft. In the case where the pump 313 is a mechanical water pump that is driven to rotate by the crankshaft 34, the flow rate of the cooling water may be increased by increasing the engine speed.

The execution of the flow rate increase processing shown in fig. 9 may be omitted.

The deposit amount DP is calculated based on the knock learning value AGKNK, but may be calculated by another method.

The fuel injection valve 31 may be an in-cylinder injection type fuel injection valve that directly injects fuel into the cylinder of the internal combustion engine 10.

The vehicle 500 is not limited to the hybrid vehicle, and may be a vehicle including only an internal combustion engine as a prime mover, which performs intermittent operation control for automatic stop and automatic start.

The control device 100 is not limited to a device that includes the CPU110 and the memory 120 and executes software processing. For example, the control device 100 may include a dedicated hardware circuit (e.g., ASIC) that performs at least a part of the software processing executed in each of the above embodiments. That is, the control device 100 may be configured as any one of the following (a) to (c). (a) The processing device includes a processing device that executes all of the above-described processes in accordance with a program, and a program storage device (including a non-transitory computer-readable storage medium) such as a memory that stores the program. (b) The apparatus includes a processing device and a program storage device for executing a part of the above processes in accordance with a program, and a dedicated hardware circuit for executing the remaining processes. (c) The apparatus includes a dedicated hardware circuit for executing all of the above processes. 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 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.

Claims

1. A control device for an internal combustion engine,

the control device is configured to execute intermittent operation control for executing automatic stop and automatic start of the internal combustion engine and knock control for suppressing occurrence of knocking by adjusting an ignition timing of the internal combustion engine,

the control device is configured to execute a delay amount increase process,

in the retard amount increase process, when a temperature of cooling water of the internal combustion engine is equal to or higher than a predetermined water temperature threshold, the retard amount of the ignition timing is increased and corrected by a retard correction amount calculated by the knock control, the retard correction amount being calculated based on the temperature of the cooling water,

in the delay amount increasing process, a process is performed in which the delay correction amount calculated during a period from the start of the automatic start until a predetermined period elapses is larger than the delay correction amount calculated after the predetermined period elapses from the start of the automatic start.

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

in the retard amount increase process, a process of acquiring an amount of deposits accumulated in a combustion chamber of the internal combustion engine is executed, and a process of increasing the retard correction amount is executed as the acquired amount of deposits increases.

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

the internal combustion engine is provided with a cooling device having a pump for circulating cooling water of the internal combustion engine,

the control device is configured to execute a flow rate increasing process of increasing a flow rate of the cooling water discharged from the pump after the start of the automatic start as an operation stop time of the internal combustion engine before the automatic start becomes longer.

4. A control device for an internal combustion engine,

the control device is configured to execute a delay amount increase process and a water temperature threshold value setting process,

in the retard amount increase process, the retard amount of the ignition timing is increased and corrected when a cooling water temperature of the internal combustion engine, which is detected by a water temperature sensor, is equal to or higher than a predetermined water temperature threshold value, the retard amount being calculated by the knock control,

in the water temperature threshold value setting process, the water temperature threshold value set in a period from the start of the automatic start to the elapse of a predetermined period is set to a value different from the water temperature threshold value set after the elapse of the predetermined period from the start of the automatic start.

5. The control apparatus of an internal combustion engine according to claim 4,

in the water temperature threshold value setting process, an amount of deposits accumulated in a combustion chamber of the internal combustion engine is acquired, and a process of setting the water temperature threshold value to a lower value as the acquired amount of deposits increases is executed.

6. The control apparatus of an internal combustion engine according to claim 4 or 5,

7. A control device for an internal combustion engine,

the control device is configured to execute a delay amount increasing process and a change rate threshold value setting process,

in the retard amount increase process, when a rate of change of the intake air amount when an intake air amount of the internal combustion engine is increased is equal to or greater than a predetermined rate of change threshold, a retard amount of an ignition timing is increased and corrected, the intake air amount being detected by an air amount sensor, the retard amount being calculated by the knock control,

in the change rate threshold value setting process, the change rate threshold value set in a period from the start of the automatic start to the elapse of a predetermined period is set to a value different from the change rate threshold value set after the elapse of the predetermined period from the start of the automatic start.

8. The control apparatus of an internal combustion engine according to claim 7,

in the change rate threshold value setting process, an amount of deposits accumulated in a combustion chamber of the internal combustion engine is acquired, and a process of setting the change rate threshold value to a smaller value as the acquired amount of deposits is larger is performed.

9. A method for controlling an internal combustion engine,

the control method comprises the following steps:

executing intermittent operation control for executing automatic stop and automatic start of the internal combustion engine;

executing knock control that suppresses occurrence of knock by adjusting an ignition timing of the internal combustion engine;

executing retard amount increase processing for increasing and correcting a retard amount of the ignition timing by a retard correction amount calculated by the knock control when a temperature of cooling water of the internal combustion engine is equal to or higher than a predetermined water temperature threshold, the temperature of the cooling water being detected by a water temperature sensor, the retard correction amount being calculated based on the temperature of the cooling water; and

in the delay amount increasing process, the delay correction amount calculated during a period from the start of the automatic start to the elapse of a predetermined period is made larger than the delay correction amount calculated after the elapse of the predetermined period from the start of the automatic start.

10. A method for controlling an internal combustion engine,

the control method comprises the following steps:

executing retard amount increase processing for increasing and correcting a retard amount of an ignition timing when a cooling water temperature of the internal combustion engine, which is detected by a water temperature sensor, is equal to or higher than a predetermined water temperature threshold value, the retard amount being calculated by the knock control; and

and executing a water temperature threshold value setting process of setting the water temperature threshold value set in a period from the start of the automatic activation to the elapse of a predetermined period to a value different from the water temperature threshold value set after the elapse of the predetermined period from the start of the automatic activation.

11. A method for controlling an internal combustion engine,

the control method comprises the following steps:

executing retard amount increase processing for increasing and correcting a retard amount of an ignition timing when a change rate of an intake air amount of the internal combustion engine, which is detected by an air amount sensor, is equal to or greater than a predetermined change rate threshold value when the intake air amount is increased, the retard amount being calculated by the knock control;

executing a change rate threshold value setting process in which the change rate threshold value set in a period from the start of the automatic start until a predetermined period elapses is set to a value different from the change rate threshold value set after the predetermined period elapses from the start of the automatic start.