JP7183962B2 - Control device for internal combustion engine - Google Patents

Description

The present invention relates to a control device for an internal combustion engine.

In an internal combustion engine, a fuel injection amount is increased by a specified increase value when the engine is started (for example, Patent Document 1, etc.).

JP 2015-48722 A

The increase in the fuel injection amount due to the start-up increase is set according to the amount of fuel adhering to the temperature of the intake port and the intake valve. The higher the temperature of the intake port and the intake valve, the smaller the amount of adhering fuel. Therefore, the higher the temperature of the intake port and the intake valve, the smaller the total increase in the fuel injection amount during the start-up increase.

Here, in an internal combustion engine having a plurality of cylinders, the temperature of the intake port at the start of engine start-up is substantially the same for each cylinder, but the temperature of the intake valve may differ for each cylinder. Therefore, if the total increase in the fuel injection amount during the start-up increase is made uniform for each cylinder without considering the difference in the amount of adhered fuel due to the temperature difference of the intake valve, the combustion chamber of each cylinder Since the amount of fuel supplied to the engine is not sufficient, there is a possibility that the situation may be unfavorable from the viewpoint of stabilizing the combustion of the air-fuel mixture.

A control device for an internal combustion engine for solving the above problems is applied to an internal combustion engine that includes an intake valve that opens and closes an intake port provided in each of a plurality of cylinders, and a fuel injection valve that injects fuel into the intake port. Then, the fuel injection amount is increased by a specified increase value when the engine is started. This control device adjusts the total amount of the fuel injection amount increment during execution of the fuel injection amount increase for the cylinder whose intake valve was in a closed state during operation stop before starting the engine. A total amount adjusting process is executed to increase the total amount of the cylinders whose intake valves are open during the period.

Since the opening and closing operations of the intake valves are stopped while the operation is stopped before the engine is started, in an internal combustion engine having a plurality of cylinders, the intake valves of the cylinders and the cylinders whose intake valves are stopped while the operation is stopped remain open. , there are cylinders that are stopped with the valves closed. Here, the intake valves that are closed while the operation is stopped are opened while the operation is stopped because the head portion of the intake valve is seated in the opening of the intake port provided in the cylinder head. The temperature is easier to drop than the intake valve with Therefore, the temperature of the intake valves that were in the closed state during stoppage of operation at the start of the engine is lower than the temperature of the intake valves that were in the open state during stoppage of operation at the start of the engine start. .

Therefore, when performing fuel injection at engine start-up, the amount of fuel adhering to the intake valve that was in the closed state while the operation was stopped is greater than the amount of

Therefore, in the same configuration, by executing the total amount adjustment process, the total amount of the increase in the fuel injection amount in the cylinder whose intake valve was closed during operation stop is adjusted to the intake valve opening during operation stop. It is set to be larger than the total amount of increase in the fuel injection amount in the cylinder that was in the valve state. Therefore, the total amount of fuel injection amount increment is adjusted for each cylinder in accordance with the amount of fuel adhering to the intake valve at the time of engine start-up, thereby supplying fuel to the combustion chamber of each cylinder. Since the excess or deficiency of the amount of is suppressed, the combustion of the air-fuel mixture is stabilized when the engine is started.

In the above control device, the total amount adjustment process may increase the total amount of each cylinder as the operation stop time, which is the time during which the internal combustion engine is stopped before the engine is started, is longer.

The longer the internal combustion engine is stopped, the lower the temperature of the intake valve. Therefore, the longer the operation stop time before starting the engine, the lower the temperature of the intake valve when starting the engine, and the more the amount of fuel adhering to the intake valve when starting the engine.

In this regard, in the same configuration, the longer the operation stop time and the greater the amount of fuel adhering to the intake valves at engine start, the greater the total increase in fuel injection amount. Therefore, the excess or deficiency of the amount of fuel supplied to the combustion chamber of each cylinder is further suppressed, and the combustion of the air-fuel mixture becomes more stable when the engine is started.

In the above control device, the total amount adjusting process may increase the total amount of each cylinder as the temperature of the cooling water of the internal combustion engine at the start of engine start is lower.
The lower the cooling water temperature at the start of the engine start, the lower the temperature of the intake valve, and the larger the amount of fuel adhering to the intake valve at the start of the engine start.

In this regard, in the same configuration, the lower the cooling water temperature at the start of the engine start, and the more the amount of fuel adhering to the intake valve at the start of the engine start, the greater the total amount of increase in the fuel injection amount. Therefore, the excess or deficiency of the amount of fuel supplied to the combustion chamber of each cylinder is further suppressed, and the combustion of the air-fuel mixture becomes more stable when the engine is started.

In the above control device, the operation is stopped based on the operation stop time of the internal combustion engine before engine start, the cooling water temperature of the internal combustion engine during the operation stop, and the state of the intake valve in each cylinder during the operation stop. a valve temperature estimating process for calculating the temperature of the intake valve of each cylinder in the engine, and the valve temperature estimating process is performed so that the temperature of the intake valve that is in a closed state during the operation stop is The process of calculating the temperature so as to be lower than the temperature of the intake valve that is in the open state during the operation is executed, and the total amount adjustment process is performed by calculating the temperature of the intake valve that is in the stopped state. A process may be executed in which the total amount is made larger than the total amount of the cylinder in which the temperature of the intake valve of which the operation is stopped is high.

The longer the operation stop time of the internal combustion engine or the lower the cooling water temperature of the internal combustion engine while the operation is stopped, the lower the temperature of the intake valve of each cylinder while the operation is stopped. In addition, the temperature of the intake valves during non-operation also differs depending on the state of the intake valves in the respective cylinders during non-operation. That is, the temperature of the intake valve that is closed while the operation is stopped is lower than that of the intake valve that is open. Therefore, in the same configuration, an estimated value of the temperature of the intake valve of each cylinder whose operation is stopped is calculated by executing the valve temperature estimation process.

Here, the temperature of the intake valve whose temperature is low when the operation is stopped is also low when the engine is started, so the amount of fuel that adheres when the engine is started increases. Therefore, in the same configuration, the total amount of increase in the fuel injection amount of the cylinder whose estimated temperature of the intake valve is low is made larger than the total amount of increase of the fuel injection amount of the cylinder whose temperature is high. Therefore, even with the same configuration, the total increase in the fuel injection amount is adjusted for each cylinder according to the amount of fuel adhering to the intake valve at the time of starting the engine. Since the excess or deficiency of the amount of fuel supplied can be suppressed, the combustion of the air-fuel mixture is stabilized when the engine is started.

As the processing for increasing the total amount of fuel injection amount increment due to the start-time increment, processing for increasing the total amount by increasing the increment value can be employed.
In addition, when executing the process of attenuating the increase value and ending the fuel injection amount at start-up when a specified attenuation start time elapses after starting the fuel injection amount at start-up, As the process for increasing the total amount, a process for increasing the total amount by lengthening the attenuation start time can be employed.

In addition, after starting the fuel injection amount at start, when executing the process of attenuating the above increase value at a specified attenuation speed and ending the fuel injection amount at start, the total amount of increase in the fuel injection amount due to the fuel injection at start As the processing for increasing, processing for increasing the total amount by slowing down the attenuation speed can be adopted.

In the above control device, the internal combustion engine is mounted on a vehicle having an internal combustion engine and an electric motor as a prime mover, and an exhaust passage of the internal combustion engine is provided with a catalyst for purifying exhaust gas. When a request to stop the operation of the internal combustion engine is generated during execution of the fuel increase, a stop delay process is executed to delay the stop of the operation of the internal combustion engine until the atmosphere of the catalyst becomes stoichiometric, and the request to stop the operation is performed. If the vehicle speed of the vehicle is equal to or less than a prescribed threshold value when the above occurs, a process of stopping the operation of the internal combustion engine may be executed without executing the stop delay process.

The atmosphere of the catalyst is in a rich state during execution of the fuel increase at start-up, and if the operation of the internal combustion engine is stopped in this rich state, the catalyst's exhaust purification ability will be temporarily reduced at the next engine start. There is a risk of Therefore, in the same configuration, when a request to stop the operation of the internal combustion engine is generated during execution of the fuel increase at startup, stop delay processing is executed to delay the operation of the internal combustion engine until the atmosphere of the catalyst becomes stoichiometric. As a result, it is possible to suppress such deterioration of the exhaust gas purification ability. Here, in a vehicle having an internal combustion engine and an electric motor as a prime mover, that is, a so-called hybrid vehicle, an attempt is made to improve fuel consumption by stopping the operation of the internal combustion engine. If delayed, the fuel consumption will deteriorate accordingly. In this regard, in the same configuration, if the vehicle speed is equal to or less than a specified threshold value when the operation stop request is generated, the operation of the internal combustion engine is stopped without executing the stop delay process. Therefore, under a situation where the vehicle speed is equal to or lower than the specified threshold value, it is possible to suppress deterioration of fuel consumption due to the execution of the stop delay process.

In the above control device, the internal combustion engine includes a sensor that detects the atmosphere of the catalyst, and the stop delay process determines whether the atmosphere of the catalyst is in a stoichiometric state based on the detection value of the sensor. On the other hand, when it is impossible to determine the atmosphere of the catalyst from the detected value of the sensor, the integrated amount of air that is the integrated value of the amount of air drawn into the internal combustion engine after the end of the increase at start-up is completed. becomes equal to or greater than a specified air amount threshold, the process of stopping the operation of the internal combustion engine may be executed.

Whether or not the atmosphere of the catalyst is stoichiometric can be determined based on the value detected by a sensor that detects the atmosphere of the catalyst, for example, a sensor that detects the oxygen concentration of the exhaust gas that has passed through the catalyst. However, if it cannot be determined whether or not the atmosphere of the catalyst is in a stoichiometric state based on the detection value of the sensor, the stop delay processing cannot be executed. Therefore, in the same configuration, when it is impossible to judge the atmosphere of the catalyst from the detected value of the sensor, the integrated amount of air, which is the integrated value of the amount of air drawn into the internal combustion engine after the end of the increase at the time of starting, is specified. The operation of the internal combustion engine is stopped when it can be estimated that the catalyst atmosphere is in a stoichiometric state because the air amount is equal to or greater than the threshold value. Therefore, even if it is impossible to determine the atmosphere of the catalyst based on the detected value of the sensor, the stop delay process can be executed.

In the control device described above, the air amount threshold may be variably set so that the larger the total amount, the larger the value.
As the total increase in the fuel injection amount due to the start-up increase increases, the cumulative amount of air required until the atmosphere of the catalyst becomes stoichiometric increases. In this regard, in the same configuration, the air amount threshold value is variably set so that the larger the total amount, the larger the value. can be done properly.

1 is a schematic diagram showing the configuration of a hybrid vehicle provided with a control device for an internal combustion engine according to a first embodiment; FIG. 4 is a flowchart showing the procedure of valve temperature estimation processing executed by the control device of the same embodiment; FIG. 4 is a conceptual diagram showing a mode of estimating valve temperature; 4 is a flowchart showing the procedure of port temperature estimation processing executed by the control device of the embodiment; FIG. 4 is a conceptual diagram showing a mode of estimating port temperature; 4 is a flowchart showing the procedure of total amount adjustment processing executed by the control device of the embodiment; 5 is a graph showing how the increase value is set according to the valve temperature and port temperature; 4 is a graph showing how the attenuation start time is set according to the valve temperature and port temperature; 4 is a graph showing how the damping rate is set according to the valve temperature and port temperature; 9 is a flowchart showing the procedure of total amount adjustment processing executed by the control device of the second embodiment; FIG. 4 is a conceptual diagram showing a setting mode of an increase value in the same embodiment; FIG. 4 is a conceptual diagram showing how the attenuation start time is set in the same embodiment; FIG. 4 is a conceptual diagram showing a mode of setting a damping speed in the same embodiment; 9 is a flowchart showing the procedure of valve temperature estimation processing executed by the control device of the third embodiment; FIG. 4 is a conceptual diagram showing a mode of estimating an average value of valve temperatures in the same embodiment; 10 is a flow chart showing the procedure of processing executed by the control device of the fourth embodiment; FIG. 4 is a conceptual diagram showing how an air amount threshold value is set in the same embodiment; FIG. 4 is a schematic diagram showing the state of the throttle valve in the intake passage; 10 is a flowchart showing the procedure of target opening degree setting processing executed by a control device in a modified example of each embodiment; 4 is a flow chart showing the procedure of acceleration processing executed by a control device in a modified example of each embodiment; 4 is a flow chart showing the procedure of acceleration processing executed by a control device in a modified example of each embodiment; 4 is a flow chart showing the procedure of acceleration processing executed by a control device in a modified example of each embodiment;

(First embodiment)
A first embodiment embodying a control device for an internal combustion engine will be described below with reference to FIGS. 1 to 9. FIG.

As shown in FIG. 1, a vehicle 500 is a hybrid vehicle having an internal combustion engine 10 having a plurality of cylinders and an electric motor as a prime mover. ) 71 and a second motor generator (hereinafter referred to as a second MG) 72 that is a second electric motor.

Vehicle 500 includes a planetary gear mechanism 40 . The planetary gear mechanism 40 is a mechanism for distributing the output of the internal combustion engine 10 to the rotor, which is the output shaft of the first MG 71, and the drive shaft 60 connected to the drive wheels 62. It has a ring gear 42 that is connected to it. A plurality of pinion gears meshing with both the sun gear 41 and the ring gear 42 are arranged between the sun gear 41 and the ring gear 42 , and each pinion gear is supported by a carrier 44 .

A crankshaft 34 of the internal combustion engine 10 is connected to the carrier 44 , and a rotor of the first MG 71 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 first MG 71 functions as a generator that generates power using the engine output, and also functions as a starting starter (electric motor) when the internal combustion engine 10 is started.

A rotor of the second MG 72 is connected to a drive shaft 60 via a speed reduction mechanism 50 . The second MG 72 functions as an electric motor that generates driving force for the drive wheels 62 and also functions as a generator that generates power by regenerative braking when the vehicle 500 is decelerating.

The first MG 71 and the second MG 72 exchange electric power with a battery 78 via a PCU (Power Control Unit) 200 . PCU 200 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 AC voltage and outputs the AC voltage to MGs 71 and 72, and the like.

In the internal combustion engine 10, air is drawn into a combustion chamber 30 through an intake passage 11 having a surge tank 13 and an intake port 12 formed in the cylinder head 10H, and is injected into the intake port 12 from a fuel injection valve 31. The supplied fuel is supplied to the combustion chamber 30 . When the mixture composed of air and fuel supplied to the combustion chamber 30 is ignited by the spark plug 32, the mixture burns and the piston 33 reciprocates to move the output shaft of the internal combustion engine 10. , the crankshaft 34 rotates. The air-fuel mixture after combustion is discharged from the combustion chamber 30 to the exhaust passage 21 through the exhaust port 22 formed in the cylinder head 10H. The exhaust passage 21 is provided with a three-way catalyst (hereinafter referred to as a catalyst) 23 for purifying the exhaust, which is the air-fuel mixture after combustion.

A front sensor 88 is provided upstream of the catalyst 23 in the exhaust passage 21 , and a rear sensor 89 is provided downstream of the catalyst 23 in the exhaust passage 21 . The front sensor 88 outputs a signal AFf corresponding to the air-fuel ratio of exhaust gas flowing into the catalyst 23 . A rear sensor 89 outputs a signal AFr corresponding to the oxygen concentration of the exhaust that has passed through the catalyst 23 .

The intake passage 11 is provided with a throttle valve 14 for adjusting the amount of intake air. The opening of this throttle valve 14 is adjusted by an electric motor. A water jacket 14w through which cooling water for the internal combustion engine flows is provided around the throttle valve 14. As shown in FIG.

The intake port 12 is provided with an intake valve 15 , and the exhaust port 22 is provided with an exhaust valve 25 . These intake valves 15 and exhaust valves 25 open and close with the rotation of the intake camshaft 16 and the exhaust camshaft 26 to which the rotation of the crankshaft 34 is transmitted, respectively.

The intake camshaft 16 is provided with a hydraulic variable valve mechanism 17 that changes the valve timing of the intake valves 15 by adjusting the relative phase of the intake camshaft 16 with respect to the crankshaft 34 .

The internal combustion engine 10 has an oil pump 90 that is rotationally driven by the crankshaft 34 , and the variable valve mechanism 17 is driven using the pressure of hydraulic oil fed from the oil pump 90 .

Control of internal combustion engine 10 and each control of first MG 71 and second MG 72 via PCU 200 are executed by control device 100 mounted on vehicle 500 .
The control device 100 includes a central processing unit (hereinafter referred to as CPU) 110 and a memory 120 in which control programs and data are stored. Then, the control device 100 executes various control-related processes by causing the CPU 110 to execute the programs stored in the memory 120 . Although not shown, the control device 100 is composed of a plurality of control units such as a control unit for the internal combustion engine 10 and a control unit for the PCU 200 .

A crank angle sensor 80 that detects the crank angle of the crankshaft 34 is connected to the control device 100 . The crank angle sensor 80 has an element, such as a Hall element, capable of detecting the crank angle until the engine rotation speed becomes "0" as the engine stops. The control device 100 also includes a cam angle sensor 81 for detecting the phase of the intake camshaft 16, an airflow meter 82 for detecting the intake air amount GA of the internal combustion engine 10, and a cooling water temperature THW which is the temperature of the cooling water for the internal combustion engine 10. A water temperature sensor 83 for detecting is connected. The control device 100 also includes an outside air temperature sensor 84 that detects the outside air temperature THout, a vehicle speed sensor 85 that detects the vehicle speed SP of the vehicle 500, an accelerator position sensor 86 that detects an accelerator operation amount ACCP, which is the operation amount of the accelerator pedal, A pressure sensor 87 is connected to detect the hydraulic pressure PR, which is the pressure of the hydraulic oil fed from the oil pump 90 . The front sensor 88 and the rear sensor 89 are also connected to the control device 100 . Output signals from these various sensors are input to the control device 100 . The control device 100 calculates the engine rotation speed NE based on the output signal Scr of the crank angle sensor 80, and calculates the intake valve 15 speed based on the output signal Scr of the crank angle sensor 80 and the output signal Sca of the cam angle sensor 81. Calculate the actual valve timing, which is the actual valve timing of Control device 100 also calculates the charging rate (hereinafter referred to as SOC) of battery 78 .

Then, the control device 100 grasps the engine operating state based on the detection signals of the various sensors, and according to the grasped engine operating state, controls the fuel injection of the fuel injection valve 31, controls the ignition timing of the spark plug 32, controls the intake air. Various engine controls such as valve timing control of the valve 15 and opening degree control of the throttle valve 14 are performed.

As the valve timing control, the control device 100 calculates a required valve timing, which is a control target value of the valve timing of the intake valve 15, based on the engine speed NE, the engine load factor KL, and the like. Then, the valve timing control of the intake valve 15 is performed by controlling the drive of the variable valve mechanism 17 so that the actual valve timing becomes the required valve timing. Note that the variable valve mechanism 17 is driven using the pressure of hydraulic oil fed from the oil pump 90 . Therefore, the control device 100 drives the variable valve mechanism 17 when the hydraulic pressure PR is equal to or higher than the prescribed threshold value PRref. Incidentally, as the threshold value PRref, the minimum hydraulic pressure required to properly drive the variable valve mechanism 17 is set.

Further, the control device 100 calculates an engine demand torque TE, which is a demand value of the output torque of the internal combustion engine 10, as the opening degree control of the throttle valve 14. FIG. Then, the required air amount GAD required to obtain the engine required torque TE is calculated, and the target opening TAp, which is the opening of the throttle valve 14 required to obtain the calculated required air amount GAD, is calculated. Then, the actual opening of the throttle valve 14 is controlled so as to achieve this target opening TAp.

Further, as the fuel injection control, the control device 100 calculates a basic injection amount, which is a basic value of the amount of fuel injected from the fuel injection valve 31, based on the intake air amount GA, the engine rotation speed NE, and the like. Then, by correcting the basic injection amount according to the engine operating state, the final injection amount is calculated, and drive control of the fuel injection valve 31 is performed so that the final injection amount is injected.

The control device 100 executes a start-time increase as one of the corrections of the basic injection amount according to the engine operating state. This start-up amount increase is performed at the start of engine start-up for the purpose of stabilizing the combustion state of the air-fuel mixture at engine start-up. That is, the fuel injection amount of the fuel injection valve 31 is increased in order to compensate for the shortage of fuel supplied to the combustion chamber 30 due to the fuel adhering to the intake port 12 and the intake valve 15 when the engine is started. It is basically implemented as follows.

When this start-time increase is started, first, the basic injection amount is increased by a specified increase value Z, thereby increasing the fuel injection amount. Then, when the specified attenuation start time DECT has passed since the starting increase, the increase value Z is attenuated at a specified decay speed DECS, and the starting increase is terminated. The setting of the increase value Z, the attenuation start time DECT, and the attenuation speed DECS will be described later.

Also, it is a value determined by the increase value Z, the decay start time DECT, and the decay speed DECS, and is the total amount of increase in the fuel injection amount during the execution of the increase at startup, that is, the amount from the start to the end of the increase at startup. The total amount of the increase in the fuel injection amount increased by the increase value Z during the interval is hereinafter simply referred to as the total amount ZT.

Incidentally, the greater the increase value Z is, the greater the increase in the fuel injection amount per unit time, or the longer the attenuation start time DECT and the later the attenuation start timing of the increase value Z, or the greater the attenuation speed DECS. The slower the engine is, the smaller the amount of decrease in fuel increase per unit time, the larger the total amount ZT. Therefore, when the temperature of the intake port 12 and the intake valve 15 is low at the start of the engine start, and the amount of fuel adhering to the intake port 12 and the intake valve 15 increases, the amount of fuel supplied to the combustion chamber 30 decreases. To make up for the shortage, the total amount ZT is set to a large amount.

Then, the control device 100 calculates a required vehicle output, which is a required value of the driving force of the vehicle 500, based on the accelerator operation amount ACCP, the vehicle speed SP, and the like. Further, the control device 100 controls the engine required torque TE, which is the required value of the output torque of the internal combustion engine 10, and the first MG request, which is the required value of the power running torque or regenerative torque of the first MG 71, based on the vehicle required output, SOC, and the like. A torque TM1 and a second MG request torque TM2, which is a request value of power running torque or regenerative torque of the second MG 72, are calculated respectively. Then, the control device 100 performs output control of the internal combustion engine 10 according to the engine required torque TE, and performs torque control of the first MG 71 and the second MG 72 according to the first MG required torque TM1 and the second MG required torque TM2. Thus, torque control necessary for running the vehicle 500 is performed.

Further, when the engine demand torque TE is "0" and the condition for stopping the operation of the internal combustion engine 10 is satisfied, the control device 100 assumes that there is a request to stop the operation of the internal combustion engine 10. The control device 100 automatically stops the operation of the internal combustion engine 10 by stopping fuel injection and ignition. Then, when the engine demand torque TE exceeds "0" and the condition for starting the internal combustion engine 10 that has stopped operating is satisfied, the control device 100 assumes that there is a request to start the internal combustion engine 10. By starting cranking, fuel injection and ignition by the first MG 71, the internal combustion engine 10, which has been stopped, is automatically started. In this manner, the control device 100 performs intermittent operation of the internal combustion engine 10 by automatically stopping and starting the internal combustion engine 10 . Further, the control device 100 stops the operation of the internal combustion engine 10 when the vehicle driver requests to stop the operation of the internal combustion engine 10 . Further, the control device 100 starts the internal combustion engine 10 when the vehicle driver requests to start the internal combustion engine 10 .

Next, various processes executed by the control device 100 in order to execute the starting fuel increase will be described with reference to FIGS. 2 to 9. FIG.
FIG. 2 shows the procedure of the valve temperature estimation process for calculating the valve temperature THV, which is the estimated temperature of the intake valve 15 when the internal combustion engine 10 is stopped, for each cylinder. The valve temperature estimation process is repeatedly executed by the control device 100 while the operation of the internal combustion engine 10 is stopped. Also, hereinafter, step numbers are represented by numerals prefixed with "S".

When starting this process, the control device 100 acquires the current shutdown time TS, the current cooling water temperature THW, and the crank angle at stop CRAS (S100). The operation stop time TS starts to be measured when the operation of the internal combustion engine 10 is automatically stopped, or when the operation of the internal combustion engine 10 is stopped in response to a vehicle driver's request to stop the operation of the internal combustion engine 10 . Then, when the stopped internal combustion engine 10 is started, the stop time TS is reset to "0". The stop crank angle CRAS is the crank angle when the internal combustion engine 10 is in the current stopped state, that is, the crank angle when the operation of the internal combustion engine 10 is stopped by the stop request and the rotation of the crankshaft 34 is stopped. is a corner. The control device 100 stores the stopped crank angle CRAS in the memory 120 when the operation of the internal combustion engine 10 is stopped.

Next, the control device 100 calculates the valve temperature THV for each cylinder based on the obtained operation stop time TS, cooling water temperature THW, and stop crank angle CRAS (S110). This valve temperature THV is calculated as follows.

As shown in FIG. 3, the valve temperature THV is calculated such that the longer the shutdown time TS, the lower the valve temperature THV. This is because the longer the shutdown time TS, the lower the temperature of the intake valve 15 . Further, the valve temperature THV is calculated so that the lower the cooling water temperature THW, the lower the valve temperature THV. This is because the temperature of the intake valve 15 decreases as the cooling water temperature THW during shutdown is lower.

Further, the control device 100 distinguishes between the cylinders in which the intake valves 15 are open and the cylinders in which the intake valves 15 are closed based on the crank angle CRAS at stop. The valve temperature THV of the cylinder in which the intake valve 15 is closed is calculated so as to be lower than the valve temperature THV of the cylinder in which the intake valve 15 is open. This is for the following reasons.

That is, since the opening and closing operations of the intake valves 15 are stopped during operation stop before starting the engine, in the internal combustion engine 10 having a plurality of cylinders, the intake valves 15 are stopped in an open state during operation stop. There are cylinders that are closed and cylinders that are stopped with the valves closed. Here, the intake valve 15, which is in the closed state while the operation is stopped, has its head portion seated in the opening of the intake port 12 provided in the cylinder head 10H. The temperature is more likely to drop than the intake valve 15 which is set to . Therefore, the temperature of the intake valve 15 that is closed while the operation is stopped is lower than the temperature of the intake valve 15 that is open while the operation is stopped.

After calculating the valve temperature THV for each cylinder in this manner, the control device 100 once terminates this process. By repeatedly executing such a valve temperature estimation process while the internal combustion engine 10 is stopped, the valve temperature THV during the stopped operation is updated.

FIG. 4 shows the port temperature estimation process for calculating the port temperature THP, which is the estimated temperature of the wall surface of the intake port 12 when the internal combustion engine 10 is stopped. This port temperature estimation process is also repeatedly executed by the control device 100 while the operation of the internal combustion engine 10 is stopped. Since the temperature of the intake port 12 is substantially the same for each cylinder while the operation of the internal combustion engine 10 is stopped, the port temperature THP calculated by this process is used as a value indicating the temperature of the intake port 12 of each cylinder. be.

When this process is started, the control device 100 acquires the current shutdown time TS and the current cooling water temperature THW (S150).
Next, the control device 100 calculates the port temperature THP based on the acquired shutdown time TS and cooling water temperature THW (S160). This port temperature THP is calculated as follows.

As shown in FIG. 5, the port temperature THP is calculated such that the longer the shutdown time TS, the lower the port temperature THP. This is because the wall surface temperature of the intake port 12 decreases as the shutdown time TS increases. Further, the valve temperature THV is calculated so that the lower the cooling water temperature THW, the lower the valve temperature THV. This is because the wall surface temperature of the intake port 12 decreases as the cooling water temperature THW during shutdown is lower.

After calculating the port temperature THP in this manner, the control device 100 once terminates this process. By repeatedly executing such port temperature estimation processing while the operation of the internal combustion engine 10 is stopped, the port temperature THP while the operation is stopped is updated.

FIG. 6 shows the processing procedure of the total amount adjustment process for adjusting the total amount ZT by calculating the increase value Z, the attenuation start time DECT, and the attenuation speed DECS. Note that the control device 100 starts executing the series of processes shown in FIG.

When starting this process, the control device 100 acquires the currently calculated valve temperature THV and port temperature THP of each cylinder (S200). By executing the process of S200, the control device 100 updates the latest values of each valve temperature THV and the port temperature THP calculated while the operation is stopped to the valve temperature THV of each cylinder and the internal combustion engine 10 is obtained as the port temperature THP of

Next, the control device 100 calculates the increase value Z, the damping start time DECT, and the damping speed DECS based on the valve temperature THV of each cylinder and the port temperature THP of the internal combustion engine 10 when the engine starts (S210 ).

As shown in FIG. 7, the lower the port temperature THP at the start of the engine start, the larger the increase value Z is set. Further, the increase value Z is set to a larger value for a cylinder having a lower valve temperature THV at the start of the engine start. Therefore, the total amount ZT that is increased by the increase at the time of starting increases for a cylinder in which the valve temperature THV at the start of the engine start is low and the amount of fuel adhering to the intake valve 15 is large.

As shown in FIG. 8, the lower the port temperature THP at the start of the engine start, the longer the decay start time DECT is set. Further, the damping start time DECT is set longer for a cylinder having a lower valve temperature THV at the start of the engine start. Therefore, the total amount ZT that is increased by the increase at the time of starting increases for a cylinder in which the valve temperature THV at the start of the engine start is low and the amount of fuel adhering to the intake valve 15 is large.

As shown in FIG. 9, the lower the port temperature THP at the start of the engine start, the slower the decay speed DECS is set. Further, the damping speed DECS is set to a slower time for a cylinder having a lower valve temperature THV at the start of the engine start. Therefore, the total amount ZT that is increased by the increase at the time of starting increases for a cylinder in which the valve temperature THV at the start of the engine start is low and the amount of fuel adhering to the intake valve 15 is large.

When the increase value Z, the attenuation start time DECT, and the attenuation speed DECS are thus calculated, the control device 100 terminates this process. Then, when the engine is started, the control device 100 uses the calculated increase value Z, decay start time DECT, and decay speed DECS to perform start-time increase.

The operation and effects of this embodiment will be described.
(1-1) The longer the shutdown time TS or the lower the cooling water temperature THW during shutdown, the lower the temperature of the intake valve 15 of each cylinder during shutdown. Further, the temperature of the intake valve 15 during stop operation also differs depending on the state of the intake valve 15 in each cylinder during stop operation. That is, the temperature of the intake valve 15 that is closed while the operation is stopped is lower than that of the intake valve 15 that is open. Therefore, in the present embodiment, the valve temperature estimation process is executed to calculate the valve temperature THV, which is an estimated value of the temperature of the intake valve 15 of each cylinder whose operation is stopped.

Here, the temperature of the intake valve 15, which is low when the operation is stopped, is also low when the engine is started, so the amount of fuel that adheres when the engine is started increases. Therefore, in order to stabilize the combustion of the air-fuel mixture when starting the engine, it is necessary to increase the total amount ZT of the cylinders in which the temperature of the intake valves 15 is low.

Therefore, in the present embodiment, by executing the total amount adjustment process shown in FIG. is greater than the total amount ZT of the increment of the fuel injection amount. More specifically, the increase value Z for a cylinder with a low valve temperature THV is set to a value larger than the increase value Z for a cylinder with a high valve temperature THV. The damping start time DECT for the cylinder with the low valve temperature THV is set longer than the damping start time DECT for the cylinder with the high valve temperature THV. Further, the damping speed DECS of the cylinder with the low valve temperature THV is set to a speed slower than the damping speed DECS of the cylinder with the high valve temperature THV.

Therefore, the total amount ZT of the increment of the fuel injection amount is adjusted for each cylinder according to the amount of fuel adhering to the intake valve 15 when the engine is started. Since the excess or deficiency of the amount of fuel supplied is suppressed, the combustion of the air-fuel mixture is stabilized when the engine is started.

(Second embodiment)
Next, a second embodiment of an internal combustion engine control device will be described with reference to FIGS. 10 to 13. FIG.

In the total amount adjustment process described in the first embodiment, the increase value Z, damping start time DECT, and damping speed DECS for adjusting the total amount ZT are set based on the calculated valve temperature THV and port temperature THP.

On the other hand, in the present embodiment, without calculating the valve temperature THV and the port temperature THP, the increase value Z and The damping start time DECT and the damping speed DECS are directly set, which is different from the first embodiment. Therefore, the present embodiment will be described below with a focus on such points of difference.

FIG. 10 shows the procedure of the total amount adjustment process executed by the control device 100. As shown in FIG. It should be noted that the control device 100 starts executing the series of processes shown in FIG.

When starting this process, the control device 100 acquires the operation stop time TS, the current cooling water temperature THW, that is, the cooling water temperature THW at the start of the engine start, and the crank angle CRAS at stop (S300).

Next, the control device 100 calculates the increase value Z, the damping start time DECT, and the damping speed DECS based on the acquired operation stop time TS, cooling water temperature THW, and crank angle CRAS at stop (S310).

As shown in FIG. 11, the longer the shutdown time TS is, the larger the increase value Z is set. This is because the longer the shutdown time TS, the lower the temperature of the intake valve 15 and the intake port 12 when starting the engine, and the total amount ZT needs to be increased. Further, the increase value Z is set to a larger value as the cooling water temperature THW is lower. This is because the lower the cooling water temperature THW when starting the engine, the lower the temperature of the intake valve 15 and the intake port 12 when starting the engine, and it is necessary to increase the total amount ZT. .

Further, the control device 100 distinguishes between the cylinders in which the intake valves 15 were open and the cylinders in which the intake valves 15 were closed while the operation was stopped, based on the stopped crank angle CRAS. Then, the increase value Z of the cylinder whose intake valve 15 was closed is set to a value larger than the increase value Z of the cylinder whose intake valve 15 was open. This is for the following reasons.

That is, as described above, the temperature of the intake valve 15 that is closed while the operation is stopped is lower than the temperature of the intake valve 15 that is open while the operation is stopped. Therefore, the temperature of the intake valve 15 when starting the engine is higher for the intake valve 15 that was closed while the operation was stopped than for the intake valve 15 that was open while the operation was stopped. This is because the total amount ZT of the cylinders in which the temperatures of the intake valves 15 are low needs to be larger than the total amount ZT of the cylinders in which the temperatures of the intake valves 15 are high.

Further, as shown in FIG. 12, the longer the operation stop time TS, the longer the decay start time DECT is set. This is also because the longer the shutdown time TS, the lower the temperature of the intake valve 15 and the intake port 12 when starting the engine, and the total amount ZT needs to be increased. Also, the lower the cooling water temperature THW, the longer the decay start time DECT is set. This is also because the lower the cooling water temperature THW when starting the engine, the lower the temperature of the intake valve 15 and the intake port 12 when starting the engine, and it is necessary to increase the total amount ZT. .

Further, the control device 100 distinguishes between the cylinders in which the intake valves 15 were open and the cylinders in which the intake valves 15 were closed while the operation was stopped, based on the stopped crank angle CRAS. The attenuation start time DECT of the cylinder whose intake valve 15 was closed is set to be longer than the attenuation start time DECT of the cylinder whose intake valve 15 was open. As also described above, the temperature of the intake valve 15 when starting the engine is higher than the temperature of the intake valve 15 that was in the open state while the operation was stopped. This is because the valve 15 is lower, and the total amount ZT of the cylinders in which the temperature of the intake valves 15 is low must be larger than the total amount ZT of the cylinders in which the temperature of the intake valves 15 is high.

Further, as shown in FIG. 13, the longer the shutdown time TS, the slower the decay speed DECS. This is also because the longer the shutdown time TS, the lower the temperature of the intake valve 15 and the intake port 12 when starting the engine, and the total amount ZT needs to be increased. Also, the lower the cooling water temperature THW, the slower the damping speed DECS. This is also because the lower the cooling water temperature THW when starting the engine, the lower the temperature of the intake valve 15 and the intake port 12 when starting the engine, and it is necessary to increase the total amount ZT. .

Further, the control device 100 distinguishes between the cylinders in which the intake valves 15 were open and the cylinders in which the intake valves 15 were closed while the operation was stopped, based on the stopped crank angle CRAS. Then, the damping speed DECS of the cylinder whose intake valve 15 was closed is made slower than the damping speed DECS of the cylinder whose intake valve 15 was open. As also described above, the temperature of the intake valve 15 when starting the engine is higher than the temperature of the intake valve 15 that was in the open state while the operation was stopped. This is because the valve 15 is lower, and the total amount ZT of the cylinders in which the temperature of the intake valves 15 is low must be larger than the total amount ZT of the cylinders in which the temperature of the intake valves 15 is high.

When the increase value Z, the attenuation start time DECT, and the attenuation speed DECS are thus calculated, the control device 100 terminates this process. Then, when the engine is started, the control device 100 uses the calculated increase value Z, decay start time DECT, and decay speed DECS to perform start-time increase.

The operation and effects of this embodiment will be described.
(2-1) By executing the total amount adjustment process, the total amount ZT of the increase in the fuel injection amount in the cylinder whose intake valve 15 was closed during operation stop is is made larger than the total amount ZT of the increase in the fuel injection amount in the cylinder whose valve was in the open state. Therefore, in this embodiment as well, the total amount ZT of the increase in the fuel injection amount is adjusted for each cylinder according to the amount of fuel adhering to the intake valve 15 when the engine is started. Since the excess or deficiency of the amount of fuel supplied to the combustion chamber 30 can be suppressed, the combustion of the air-fuel mixture is stabilized when the engine is started.

(2-2) The longer the operation stop time TS and the larger the amount of fuel adhering to the intake valve 15 when the engine is started, the larger the total amount ZT of the increment of the fuel injection amount. Therefore, excess or deficiency of the amount of fuel supplied to the combustion chamber 30 of each cylinder can be further suppressed, and the combustion of the air-fuel mixture becomes more stable when the engine is started.

(2-3) The lower the cooling water temperature THW at the start of the engine start and the greater the amount of fuel adhering to the intake valve 15 at the start of the engine start, the greater the total amount ZT of the increment of the fuel injection amount. Therefore, excess or deficiency of the amount of fuel supplied to the combustion chamber 30 of each cylinder can be further suppressed, and the combustion of the air-fuel mixture becomes more stable when the engine is started.

(Third embodiment)
Next, a third embodiment of an internal combustion engine control device will be described with reference to FIGS. 14 and 15. FIG.

In the valve temperature estimating process described in the above-described first embodiment, by grasping the valve opening state and the valve closing state of the intake valve 15 of each cylinder while the operation is stopped based on the stopped crank angle CRAS, A valve temperature THV was calculated.

On the other hand, in the present embodiment, as the crank angle sensor 80, a sensor that makes it difficult to detect the crank angle when the engine speed approaches "0", such as an electromagnetic pickup type sensor, is used. The stopping crank angle CRAS cannot be detected. Therefore, it is not possible to grasp whether the state of the intake valve 15 of each cylinder is open or closed while the operation is stopped.

Therefore, in the present embodiment, valve temperature estimation processing different from that in the first embodiment is executed, and this point is different from the first embodiment. Therefore, the present embodiment will be described below with a focus on such points of difference.

FIG. 14 shows the valve temperature estimation process of this embodiment. This valve temperature estimation process is also repeatedly executed by the control device 100 while the operation of the internal combustion engine 10 is stopped.
When this process is started, the control device 100 acquires the operation stop time TS and the current cooling water temperature THW (S400).

Next, the control device 100 calculates the valve temperature THV of the intake valve 15 based on the obtained operation stop time TS and cooling water temperature THW (S410).
Here, even if the state of the intake valve 15 of each cylinder during stoppage of operation is unknown, by conducting a compatibility test based on the stoppage time TS and the cooling water temperature THW during stoppage of operation, the valve open state during stoppage of operation can be determined. It is possible to estimate the average value of the temperature of the intake valve 15 that was at and the temperature of the intake valve 15 that was in the closed state while the operation was stopped. Therefore, in the present embodiment, the average temperature of the intake valve 15 of each cylinder is calculated as the valve temperature THV.

As shown in FIG. 15, the valve temperature THV is calculated such that the longer the shutdown time TS, the lower the valve temperature THV. This is because the longer the shutdown time TS, the lower the temperature of the intake valve 15 . Further, the valve temperature THV is calculated so that the lower the cooling water temperature THW, the lower the valve temperature THV. This is because the temperature of the intake valve 15 decreases as the cooling water temperature THW during shutdown is lower.

After calculating the valve temperature THV in this manner, the control device 100 once terminates this process. By repeatedly executing such a valve temperature estimation process while the internal combustion engine 10 is stopped, the valve temperature THV during the stopped operation is updated. When executing the total amount adjustment process shown in FIG. 6 at engine start-up, the valve temperature THV is obtained, and the total amount ZT is adjusted based on the valve temperature THV and the port temperature THP.

The operation and effects of this embodiment will be described.
(3-1) Based on the operation stop time TS and the cooling water temperature THW, the temperature of the intake valve 15 that was open while the operation was stopped and the intake valve 15 that was closed while the operation was stopped The valve temperature THV, which is the average value of the temperatures of , is calculated. Then, as the valve temperature THV is lower, the process of increasing the total amount ZT of the increment of the fuel injection amount is executed. Therefore, according to the present embodiment, although the total amount ZT of the increase in the fuel injection amount cannot be adjusted for each cylinder, even if the state of the intake valve 15 of each cylinder during operation stop is unknown, , at least the total amount ZT is adjusted according to the amount of fuel adhering to the intake valve 15 when the engine is started. As a result, excess or deficiency of the amount of fuel supplied to the combustion chamber 30 can be suppressed, so that the combustion of the air-fuel mixture is stabilized when the engine is started.

(Fourth embodiment)
Next, a fourth embodiment of the internal combustion engine control device will be described with reference to FIGS. 16 and 17. FIG.

The atmosphere of the catalyst 23 is in a rich state during execution of the above-described start-time increase. may temporarily decrease. Therefore, in the present embodiment, when a request to stop the operation of the internal combustion engine 10 is generated during execution of the fuel increase at startup, stop delay processing delays the operation stop of the internal combustion engine 10 until the atmosphere of the catalyst 23 becomes stoichiometric. is carried out, thereby suppressing the deterioration of such exhaust purification ability.

Here, in the hybrid vehicle 500 including the internal combustion engine and the electric motor as a prime mover, the fuel consumption is improved by stopping the operation of the internal combustion engine 10, etc. However, the stop delay processing is executed to stop the operation of the internal combustion engine 10. is delayed, the fuel consumption will be worsened accordingly. Therefore, in the present embodiment, the control device 100 performs the process shown in FIG. 10 to suppress such deterioration of fuel consumption.

FIG. 16 shows the procedure of the process that the control device 100 starts executing when a request to stop the operation of the internal combustion engine 10 is generated during the execution of the fuel increase at startup.
When starting this process, the control device 100 determines whether or not the current vehicle speed SP is equal to or less than the threshold value SPref (S500). As this threshold value SPref, a low vehicle speed at which the vehicle 500 can run only with the torque of the second MG 72 is set in advance.

When determining that the vehicle speed SP exceeds the threshold value SPref (S500: NO), the control device 100 determines whether or not the increase value Z is currently attenuating (S510). Then, when determining that the increase value Z is attenuating (S510: YES), the control device 100 executes the process of S530. On the other hand, if it is determined that the increase value Z is not attenuating (S510: NO), that is, if the decrease of the increase value Z has not yet started, the controller 100 forces the increase value Z to attenuate. Start (S520). Then, the process of S530 is executed. Incidentally, when the attenuation of the increase value Z is completed and the increase at start-up is completed, the atmosphere of the catalyst 23 becomes stoichiometric. After the end, it is desirable to temporarily set the air-fuel ratio of the air-fuel mixture to an air-fuel ratio leaner than the stoichiometric air-fuel ratio.

At S530 described above, the control device 100 determines whether or not the atmosphere of the catalyst 23 can be determined based on the value detected by the rear sensor 89 . In S530, if the rear sensor 89 cannot detect the oxygen concentration, such as when the rear sensor 89 is inactive, or when it is determined that the rear sensor 89 has an abnormality, the control device 100 , it is determined that the atmosphere of the catalyst 23 cannot be determined based on the detection value of the rear sensor 89 . On the other hand, when the rear sensor 89 is in an activated state without any abnormality and the oxygen concentration can be detected by the rear sensor 89, the controller 100 is in a state where the atmosphere of the catalyst 23 can be determined based on the detected value of the rear sensor 89. Determine that there is.

If it is determined in S530 that the atmosphere of the catalyst 23 can be determined based on the detection value of the rear sensor 89 (S530: YES), the control device 100 determines the atmosphere of the catalyst 23 based on the detection value of the rear sensor 89. is in a stoichiometric state (S540). The control device 100 repeatedly executes the process of S540 until it determines that the atmosphere of the catalyst 23 is in a stoichiometric state.

When determining that the atmosphere of the catalyst 23 is in a stoichiometric state (S540: YES), the control device 100 stops the operation of the internal combustion engine 10 by stopping fuel injection and ignition (S570). After executing the stop delay process for delaying the stoppage of the internal combustion engine 10 until the atmosphere of the catalyst 23 becomes stoichiometric even if the stoppage request is generated, the control device 100 ends this process.

If it is determined in S530 that the atmosphere of the catalyst 23 cannot be determined based on the value detected by the rear sensor 89 (S530: NO), the control device 100 controls the temperature of the air based on the cooling water temperature THW at the start of the engine start. A quantity threshold GASref is calculated (S550). The air amount threshold GASref is an integrated amount of air obtained by integrating the amount of air drawn into the internal combustion engine 10 from the end of the start-up increase until the atmosphere of the catalyst 23 becomes stoichiometric.

Here, the larger the total amount ZT of the increase in fuel injection amount due to the start-up increase, the larger the integrated air amount GAS required until the atmosphere of the catalyst 23 becomes stoichiometric. As described above, the total amount ZT is increased as the valve temperature THV and the port temperature THP at the start of the engine are lower. The lower the cooling water temperature THW when the engine starts, that is, the lower the cooling water temperature THW obtained last while the operation is stopped, the lower the temperature. Therefore, the total amount ZT increases as the cooling water temperature THW at the start of engine starting is lower.

Therefore, as shown in FIG. 17, the control device 100 sets the air amount threshold GASref so that the value of the air amount threshold GASref increases as the cooling water temperature THW at the start of the engine start decreases and the total amount ZT increases. The value of GASref is variably set based on the cooling water temperature THW at the start of engine start. The air amount threshold GASref may be set based on the total amount ZT, the increase value Z, the decay start time DECT, and the decay speed DECS.

After calculating the air amount threshold GASref in this manner, the control device 100 determines whether or not the current integrated air amount GAS is equal to or greater than the air amount threshold GASref (S560). The integrated air amount GAS is a time-integrated value of the intake air amount GA detected after the start-up increase is completed, and is measured by the control device 100 . The control device 100 repeatedly executes the process of S560 until it determines that the cumulative air amount GAS is equal to or greater than the air amount threshold GASref.

Then, if it is determined that the accumulated air amount GAS is equal to or greater than the air amount threshold value GASref (S560: YES), the control device 100 stops the operation of the internal combustion engine 10 by executing the process of S570. Even if an operation stop request is generated in this way, if a stop delay process is executed to delay the operation stop of the internal combustion engine 10 until it is determined that the atmosphere of the catalyst 23 is in a stoichiometric state based on the accumulated air amount GAS, the control The device 100 ends this process.

On the other hand, if it is determined in S500 that the vehicle speed SP is equal to or lower than the threshold value SPref (S500: YES), the control device 100 executes the process of S570 without executing the stop delay process. , the operation of the internal combustion engine 10 is stopped, and the process ends.

Next, the operation and effects of this embodiment will be described.
(4-1) If a negative determination is made in S500 of FIG. 16, and the vehicle speed SP at the time when the operation stop request is generated during the execution of the fuel increase at startup is equal to or less than the prescribed threshold value SPref, then S570 of FIG. , the operation of the internal combustion engine 10 is stopped without executing the stop delay process. Therefore, in a situation where the vehicle speed SP is equal to or lower than the threshold value SPre, it is possible to suppress deterioration in fuel consumption due to execution of the stop delay process.

(4-2) Whether or not the atmosphere of the catalyst 23 is in a stoichiometric state can be determined based on the detection value of the rear sensor 89 that detects the oxygen concentration of the exhaust gas that has passed through the catalyst 23 . However, if it cannot be determined whether or not the atmosphere of the catalyst 23 is in a stoichiometric state based on the detection value of the rear sensor 89, the stop delay processing cannot be executed. Therefore, in the present embodiment, when a negative determination is made in S530 of FIG. The operation of the internal combustion engine 10 is stopped when it can be estimated that the air amount threshold GASref is exceeded and the atmosphere of the catalyst 23 is in a stoichiometric state. Therefore, even when the atmosphere of the catalyst 23 cannot be determined based on the detected value of the rear sensor 89, the stop delay process can be executed.

(4-3) As the total amount ZT of the increased amount of fuel injection due to the increased amount at start-up increases, the integrated air amount GAS required until the atmosphere of the catalyst 23 becomes stoichiometric increases. In this regard, in the present embodiment, the air amount threshold GASref is variably set to a larger value as the cooling water temperature THW at the start of engine start is lower and the total amount ZT increases. , it is possible to appropriately determine whether or not the atmosphere of the catalyst 23 is in a stoichiometric state.

It should be noted that each of the above-described embodiments can be implemented with the following modifications. Each of the above-described embodiments and the following modifications can be implemented in combination with each other within a technically consistent range.

・In order to adjust the total amount ZT, the increase value Z, the damping start time DECT, and the damping speed DECS are variably set. Alternatively, any one of the increase value Z, the decay start time DECT, and the decay speed DECS may be variably set, while the other two may be fixed values. Alternatively, any two of the increase value Z, the decay start time DECT, and the decay speed DECS may be variably set, and the remaining one may be set to a fixed value.

In the second embodiment, the total amount ZT is adjusted based on the state of the intake valve 15, the shutdown time TS, and the cooling water temperature THW, but the adjustment of the total amount ZT based on the shutdown time TS may be omitted. Also in this case, effects other than the above (2-2) can be obtained. Also, the adjustment of the total amount ZT based on the cooling water temperature THW may be omitted, and even in this case, effects other than the above (2-3) can be obtained. Further, the adjustment of the total amount ZT based on the shutdown time TS and the cooling water temperature THW may be omitted, and even in this case, effects other than the above (2-2) and (2-3) can be obtained.

Incidentally, as described above, the longer the shutdown time TS or the lower the cooling water temperature THW at engine start-up, the lower the temperature of the intake valve 15 and the greater the amount of fuel that adheres at engine start-up. Therefore, more simply, the total amount ZT is adjusted so that the total amount ZT increases as the shutdown time TS is longer, or the total amount ZT is adjusted so that the total amount ZT increases as the cooling water temperature THW is lower. You may

- The air amount threshold value GASref described in the fourth embodiment may be set to a fixed value. Even in this case, effects other than the above (4-3) can be obtained.
- The processing of S530, S550, and S560 described in the fourth embodiment is omitted. Then, the process of S540 may be executed after the process of S520 or after an affirmative determination is made in S510. Even in this case, the effects described in (4-1) above can be obtained.

- The adjustment of the total amount ZT according to the amount of fuel adhering to the intake port 12 may be performed in another manner.
- Vehicles to which each of the above-described embodiments and modifications thereof are applied are not limited to hybrid vehicles, and may be vehicles having only an internal combustion engine as a prime mover of the vehicle.

- The control device 100 includes a CPU 110 and a memory 120, and is not limited to executing software processing. For example, a dedicated hardware circuit (eg, ASIC, etc.) that processes at least part of the software processing executed in each of the above embodiments may be provided. That is, the control device 100 may have any one of the following configurations (a) to (c). (a) A processing device that executes all of the above processes according to a program, and a program storage device such as a memory that stores the program. (b) A processing device and a program storage device for executing part of the above processing according to a program, and a dedicated hardware circuit for executing the remaining processing. (c) provide dedicated hardware circuitry to perform all of the above processing; Here, there may be a plurality of software processing circuits including a processing device and a program storage device, or a plurality of dedicated hardware circuits. That is, the processing may be performed by a processing circuit comprising at least one of one or more software processing circuits and one or more dedicated hardware circuits.

<Other modification examples>
In the internal combustion engine disclosed in Japanese Patent Application Laid-Open No. 2005-42682, freezing of the throttle valve is suppressed during engine operation by opening and closing the throttle valve after a predetermined period of time has passed since the start of idling.

By the way, the throttle valve 14 may freeze even when the operation of the internal combustion engine 10 is stopped.
As shown in FIG. 18, while the operation of the internal combustion engine 10 is stopped, the prescribed stop opening degree TAa is maintained. The stop opening degree TAa is the opening degree of the throttle valve 14 when power supply to the electric motor that drives the throttle valve 14 is stopped, and is an opening degree that enables shunting running, for example. When power supply to the electric motor is stopped, the opening of the throttle valve 14 is maintained at the stop opening TAa by utilizing the force of an urging member such as a spring provided in the throttle valve 14 . Incidentally, in this embodiment, the opening of the fully closed throttle valve 14 is set to "0". the amount of air increases.

On the other hand, when starting the engine, the opening of the throttle valve 14 is controlled so as to achieve a specified starting opening TAsp suitable for starting. It should be noted that the control device 100 calculates various values for the starting opening degree TAsp depending on the state of the internal combustion engine 10 at the time of engine starting and the output request by the vehicle driver.

Here, as shown in FIG. 18, when the starting opening degree TAsp is an opening degree in which the amount of intake air decreases more than the stopping opening degree TAa, that is, the starting opening degree TAsp is lower than the stopping opening degree TAa. is on the closing side, when the opening of the throttle valve 14 is changed from the stop opening TAa to the start opening TAsp, the throttle valve 14 is frozen and the outer peripheral edge 14g of the throttle valve 14 is frozen. and the intake passage 11, the ice BL will be caught between the outer peripheral edge 14g and the intake passage 11, and the opening of the throttle valve 14 will be reduced to the specified opening. You may not be able to fully control it.

In view of these problems, it is preferable to execute the target opening degree setting process shown in FIG.
The target opening degree setting process shown in FIG. 19 is started by control device 100 when an engine start request is generated.

When starting this process, the control device 100 acquires the current outside air temperature THout, the current cooling water temperature THW, and the shutdown time TS (S600).
Next, the control device 100 determines whether or not the throttle valve 14 is frozen based on the outside air temperature THout, the cooling water temperature THW, and the shutdown time TS (S610). The lower the outside air temperature THout, the lower the cooling water temperature THW, or the longer the shutdown time TS, the higher the possibility that the throttle valve 14 is frozen. Therefore, the control device 100 satisfies the conditions that the outside air temperature THout is equal to or lower than the specified threshold, the cooling water temperature THW is equal to or lower than the specified threshold, and the shutdown time TS is equal to or higher than the specified threshold. If all conditions are satisfied, it is determined that the throttle valve 14 is frozen. It should be noted that other methods may be used to determine whether the throttle valve is frozen.

When it is determined that the throttle valve 14 is not frozen (S610: NO), the control device 100 sets the starting opening degree TAsp calculated for the current engine start as the target opening degree TAp of the throttle valve 14. (S640), and the process ends.

On the other hand, when it is determined that the throttle valve 14 is frozen (S610: YES), the control device 100 sets the starting opening degree TAsp calculated for the current engine starting to an opening degree smaller than the stopping opening degree TAa. In other words, it is determined whether or not the starting opening degree TAsp is an opening degree in which the amount of intake air decreases more than the stopping opening degree TAa (S620).

Then, when it is determined that the starting opening degree TAsp is greater than the stopping opening degree TAa (S620: NO), the control device 100 executes the processing of S640 and terminates this processing. do.

On the other hand, when it is determined that the starting opening degree TAsp is smaller than the stopping opening degree TAa (S620: YES), the control device 100 adds a specified value B to the stopping opening degree TAa. is set as the target opening degree TAp of the throttle valve 14 (S630). When the process of S630 is executed, as shown in FIG. 18, the opening of the throttle valve 14 is controlled to the opening obtained by adding the specified value B to the opening at stop TAa. Also, the opening is changed in the direction in which the amount of intake air increases, that is, to the opening side.

After changing the opening degree of the throttle valve 14 to the opening side in this way, the control device 100 next sets the starting opening degree TAsp calculated for the current engine start as the target opening degree TAp of the throttle valve 14 (S640). ), the process ends.

By executing such a series of processes, it is determined in S610 that the throttle valve 14 is frozen, and in S620, the opening degree TAsp at start-up becomes smaller than the opening degree TAa at stop-time. If it is determined that the opening is in the direction of opening, the process of S630 changes the opening of the throttle valve 14 in the direction in which the amount of intake air increases from the stop opening TAa, that is, to the opening side. The ice BL is crushed by After that, the opening of the throttle valve 14 is adjusted to the starting opening TAsp by the processing of S640. As described above, the ice BL is crushed prior to the opening change to the starting opening TAsp. Even if there is a possibility of freezing, the opening of the throttle valve 14 can be controlled to a specified opening.

- The internal combustion engine described in Japanese Patent Application Laid-Open No. 2002-161766, like the internal combustion engine 10, includes a hydraulic variable valve mechanism for changing the valve timing of engine valves such as intake valves and exhaust valves. A variable valve mechanism is driven by hydraulic oil fed from an oil pump.

Here, since a certain amount of hydraulic pressure is required to drive the variable valve mechanism 17, as described above, the control device 100 sets the hydraulic pressure PR of the hydraulic oil fed from the oil pump 90 to the specified threshold value. The variable valve mechanism 17 is driven when it is equal to or higher than PRref.

By the way, when the operation of the internal combustion engine 10 is stopped and the driving of the oil pump 90 is stopped, hydraulic oil is discharged from the variable valve mechanism 17 . Therefore, the hydraulic pressure PR of the hydraulic oil fed from the oil pump 90 must be equal to or higher than the threshold value PRref until the variable valve mechanism 17 is filled with hydraulic oil after the oil pump 90 is started to be driven when the engine is started. Therefore, a delay time occurs between the start of the engine start and the time when the variable valve mechanism 17 becomes drivable. A similar delay time also occurs when the internal combustion engine 10 is provided with a hydraulic variable valve mechanism that changes the valve timing of the exhaust valve 25 .

In view of these problems, it is preferable to execute the acceleration process shown in FIG.
The acceleration process shown in FIG. 20 is started by control device 100 when the engine starts.
After starting this process, the control device 100 starts a speed increasing process for increasing the rotational speed of the oil pump 90 (S700). Since the oil pump 90 provided in the internal combustion engine 10 is a type of pump that is rotationally driven by the crankshaft 34 , the rotational speed of the oil pump 90 depends on the rotational speed of the crankshaft 34 . Therefore, in S700, the control device 100 adds a prescribed increase value ZA to the starting target speed NEsp, which is the target value of the engine speed set at the time of starting the engine, to the target speed NEp of the engine speed. By setting the target rotation speed NEp and controlling the rotation speed of the crankshaft 34 so as to achieve the target rotation speed NEp, the speed increasing process described above is executed.

Next, the control device 100 determines whether or not the hydraulic pressure PR is greater than or equal to the threshold value PRref (S710). The control device 100 repeatedly executes the process of S710 until it determines that the hydraulic pressure PR is equal to or greater than the threshold value PRref.

If it is determined that the hydraulic pressure PR is equal to or greater than the threshold value PRref (S710: YES), the control device 100 terminates the acceleration process of the oil pump 90 (S720). At S720, the control device 100 sets the starting target speed NEsp to the target rotational speed NEp, thereby increasing the engine speed, which has been the sum of the starting target speed NEsp and the increased value ZA. The rotational speed of the oil pump 90 is reduced by reducing it to the starting target speed NEsp. Then, the control device 100 ends this process.

By executing such a series of processes, the rotational speed of the oil pump 90 is increased from the start of the engine until the hydraulic pressure PR of the hydraulic oil reaches the threshold value PRref. The amount of hydraulic oil fed from 90 is increased. Therefore, compared to the case where the acceleration process is not executed, the time from the start of the engine until the hydraulic oil pressure PR reaches the threshold value PRref is shortened, thereby shortening the delay time. can be done.

In the modified example described above, the speed increasing process is executed until the hydraulic pressure PR becomes equal to or greater than the threshold value PRref. Therefore, the above acceleration processing cannot be executed.

Here, as the number of rotations of the oil pump 90 after the start of the engine increases, the total amount of hydraulic oil fed from the oil pump 90 to the variable valve mechanism 17 increases. Therefore, the determination as to whether or not the pressure of the hydraulic fluid has reached the threshold value PRref due to the filling of the hydraulic fluid in the variable valve mechanism 17 after the engine is started is based on the operation of the oil pump 90 after the start of the engine. It can be determined based on the cumulative number of rotations.

Therefore, if the internal combustion engine 10 does not have the pressure sensor 87, the acceleration process shown in FIG. 21 should be executed instead of the acceleration process shown in FIG.
The acceleration process shown in FIG. 21 is also started by control device 100 when the engine starts.

When this process is started, the control device 100 calculates an integrated threshold value NESref based on the current cooling water temperature THW, that is, the cooling water temperature THW at engine start and the operation stop time TS (S800). The integrated threshold NESref is used to determine that the variable valve mechanism 17 is filled with hydraulic fluid and the pressure of the hydraulic fluid has reached the threshold PRref when the integrated number of revolutions NES is equal to or greater than the integrated threshold NESref. is the value of The cumulative number of revolutions NES is the cumulative number of revolutions of the crankshaft 34 after the engine is started, and the control device 100 starts measuring when the engine is started. Since the oil pump 90 is rotationally driven by the crankshaft 34, the cumulative number of revolutions NES correlates with the cumulative number of revolutions of the oil pump 90 after the engine is started.

Here, the cumulative number of rotations of the oil pump 90 at which it can be determined that the pressure of the hydraulic oil has reached the threshold value PRref is the amount of hydraulic oil that has escaped from the variable valve mechanism 17 during stoppage of operation before starting the engine. increases as more The amount of hydraulic fluid that escapes from the variable valve mechanism 17 increases as the shutdown time TS increases. Further, the amount of hydraulic oil that escapes from the variable valve mechanism 17 increases as the cooling water temperature THW at engine start-up is lower and the viscosity of the hydraulic oil during shutdown is higher. Therefore, the control device 100 variably sets the integrated threshold NESref so that the lower the cooling water temperature THW or the longer the shutdown time TS, the larger the integrated threshold NESref.

Next, the control device 100 starts a speed increasing process for increasing the rotational speed of the oil pump 90 (S810). The process of S810 is the same as the process of S700 described above.
Next, the control device 100 determines whether or not the current cumulative number of revolutions NES is greater than or equal to the cumulative threshold value NESref (S820). The control device 100 repeatedly executes the process of S820 until it determines that the integrated number of rotations NES is equal to or greater than the integrated threshold value NESref.

Then, if it is determined that the integrated number of rotations NES is equal to or greater than the integrated threshold value NESref (S820: YES), the control device 100 terminates the speed increasing process of the oil pump 90 (S830). The processing of this S830 is the same as the processing of S720 described above. Then, the control device 100 ends this process.

By executing such a series of processes, the speed increasing process is executed until the cumulative number of rotations NES becomes equal to or greater than the cumulative threshold value NESref. Here, the integrated threshold value NESref is set based on the shutdown time TS and the cooling water temperature THW. Therefore, since the integrated threshold value NESref is set according to the amount of hydraulic fluid that has escaped from the variable valve mechanism 17 during the stoppage of operation before starting the engine, filling of the variable valve mechanism 17 with hydraulic fluid is completed. As a result, it becomes possible to appropriately determine that the hydraulic oil pressure has reached the threshold value PRref based on the integrated number of revolutions NES.

If the oil pump 90 is an electric pump, the driving of the oil pump 90 is started when the engine is started. The cumulative number of revolutions NES is defined as the cumulative number of revolutions of the oil pump 90 after the engine is started. The cumulative threshold value NESref is a threshold value corresponding to the cumulative number of revolutions of the oil pump 90 . By replacing the target rotational speed NEp and the starting target speed NEsp with the target rotational speed of the oil pump 90 and the target speed set at the time of starting, respectively, the speed increasing process can be executed.

In the modified example described above, the speed increasing process is executed until the hydraulic pressure PR becomes equal to or greater than the threshold value PRref. Therefore, the above acceleration processing cannot be executed.

Here, the total amount of hydraulic oil fed from the oil pump 90 to the variable valve mechanism 17 increases as the elapsed time after engine start-up increases. Therefore, whether or not the hydraulic oil pressure has reached the threshold value PRref by filling the variable valve mechanism 17 with hydraulic oil after engine startup is determined based on the elapsed time after engine startup. can be done.

Therefore, if the internal combustion engine 10 does not have the pressure sensor 87, the acceleration process shown in FIG. 22 should be executed instead of the acceleration process shown in FIG.
The acceleration process shown in FIG. 22 is also started by control device 100 when the engine starts.

When this process is started, the control device 100 calculates a time threshold value Tref based on the current cooling water temperature THW, that is, the cooling water temperature THW at engine start and the operation stop time TS (S900). The time threshold value Tref is used to determine that the variable valve mechanism 17 is filled with hydraulic oil and the pressure of the hydraulic oil has reached the threshold value PRref when the time period ST after startup is equal to or greater than the time threshold value Tref. is the value of The post-starting time ST is the elapsed time after the engine is started, and the control device 100 starts measuring when the engine is started.

Here, the elapsed time during which it can be determined that the pressure of hydraulic fluid has reached the threshold value PRref increases as the amount of hydraulic fluid that has escaped from the variable valve mechanism 17 during stoppage of operation before starting the engine increases. Become. The amount of hydraulic fluid that escapes from the variable valve mechanism 17 increases as the shutdown time TS increases. Further, the amount of hydraulic oil that escapes from the variable valve mechanism 17 increases as the cooling water temperature THW at engine start-up is lower and the viscosity of the hydraulic oil during shutdown is higher. Therefore, the control device 100 variably sets the time threshold Tref so that the lower the cooling water temperature THW or the longer the shutdown time TS, the longer the time threshold Tref.

Next, the control device 100 starts speed increasing processing for increasing the rotational speed of the oil pump 90 (S910). The process of S910 is the same as the process of S700.
Next, the control device 100 determines whether or not the current post-start time ST is greater than or equal to the time threshold Tref (S920). The control device 100 repeatedly executes the process of S920 until it determines that the post-start time ST is equal to or greater than the time threshold Tref.

Then, if it is determined that the post-starting time ST is equal to or greater than the time threshold Tref (S920: YES), the control device 100 terminates the acceleration process of the oil pump 90 (S930). The process of S930 is the same as the process of S720 described above. Then, the control device 100 ends this process.

By executing such a series of processes, the acceleration process is executed until the post-start time ST becomes equal to or greater than the time threshold Tref. Here, the time threshold Tref is set based on the shutdown time TS and the cooling water temperature THW. Therefore, since the time threshold Tref is set according to the amount of hydraulic fluid that has escaped from the variable valve mechanism 17 during the stoppage of operation before starting the engine, the filling of the variable valve mechanism 17 with hydraulic fluid is completed. As a result, it becomes possible to appropriately determine that the hydraulic oil pressure has reached the threshold value PRref based on the post-start time ST.

In this modified example as well, when the oil pump 90 is an electric pump, the oil pump 90 is started to be driven when the engine is started. By replacing the target rotational speed NEp and the starting target speed NEsp with the target rotational speed of the oil pump 90 and the target speed set at the time of starting, respectively, the speed increasing process can be executed.

Technical ideas and effects that can be grasped from the above embodiments and modifications will be described.
・Applied to an internal combustion engine equipped with an intake valve that opens and closes an intake port provided in each of a plurality of cylinders, and a fuel injection valve that injects fuel into the intake port, and increases the fuel injection amount by a specified amount when the engine is started. A control device for executing a start-up increase in which the amount is increased by a value, based on the operation stop time of the internal combustion engine before the engine start and the cooling water temperature of the internal combustion engine during the stop before the engine start. Estimate the average value of the temperature of the intake valve that was in the open state during the stop and the temperature of the intake valve that was in the closed state while the operation was stopped, and the lower the estimated average value, the higher the temperature at the start. A control device for an internal combustion engine that executes processing for increasing the total amount of an increase in the amount of fuel injection during execution of the increase.

Even if the state of the intake valves of each cylinder during shutdown is unknown, it is possible to determine the open state during shutdown by conducting a compatibility test based on the shutdown time of the internal combustion engine and the cooling water temperature of the internal combustion engine during shutdown. It is possible to estimate the mean value of the temperature of the intake valves that were at 0 and the temperature of the intake valves that were closed during shutdown. Therefore, in the same configuration, the temperature of the intake valve that was in the open state while the operation was stopped and the temperature of the intake valve that was in the closed state while the operation was stopped are determined based on the operation stop time and the cooling water temperature. I try to estimate the average value. Then, as the estimated average value is lower, the process of increasing the total amount of the fuel injection amount increase is executed. Therefore, according to the same configuration, although the total amount of increase in the fuel injection amount cannot be adjusted for each cylinder, it can be adjusted according to the amount of fuel adhering to the intake valve at least when the engine is started. As a result, excess or deficiency of the amount of fuel supplied to the combustion chamber can be suppressed, so that the combustion of the air-fuel mixture is stabilized when the engine is started.

・A control device that controls the opening of the throttle valve provided in the intake passage so that the opening is maintained at the specified stop opening while the internal combustion engine is stopped, and the opening is maintained at the specified starting opening when the engine is started. When starting the engine, a determination process for determining whether or not the throttle valve is frozen; is an opening in the direction in which the amount of intake air decreases from the opening at stop, after the opening of the throttle valve is once changed in the direction in which the amount of intake air increases from the opening at stop and adjusting the opening of the throttle valve to the starting opening.

A throttle valve of an internal combustion engine is maintained at a prescribed stop opening while the internal combustion engine is stopped, while the opening is controlled so as to achieve a prescribed start opening suitable for starting the engine when the engine is started. . Here, when the starting opening is an opening in the direction in which the amount of intake air decreases more than the stopping opening, that is, when the starting opening is closer to the closing side than the stopping opening, When changing the opening of the throttle valve from the stop opening to the start opening, if the throttle valve is frozen and ice adheres between the outer peripheral edge of the throttle valve and the intake passage, the ice is removed. is caught between the outer peripheral edge and the intake passage, and there is a possibility that the opening of the throttle valve cannot be controlled to a specified opening.

In this regard, in the same configuration, when it is determined that the throttle valve is frozen and the opening at the time of starting is an opening in the direction in which the amount of intake air decreases more than the opening at the time of stopping, The ice is crushed by once changing the opening of the throttle valve in a direction in which the amount of intake air increases more than the opening, that is, to the opening side. After that, the opening of the throttle valve is adjusted to the starting opening. Since the ice is crushed before the opening is changed to the starting opening in this way, it is possible that the ice is not caught between the outer peripheral edge and the intake passage, and as a result, the throttle valve may be frozen. Even if there is a problem, the opening of the throttle valve can be controlled to a specified opening. Whether or not the throttle valve is frozen can be determined based on the outside air temperature, water temperature, operation stop time before starting the engine, and the like.

- A control device for an internal combustion engine comprising a hydraulic variable valve mechanism for changing the valve timing of an engine valve and an oil pump for feeding hydraulic oil to the variable valve mechanism, wherein the variable valve mechanism is , a mechanism that is driven when the pressure of the hydraulic oil fed from the oil pump is equal to or higher than a specified threshold, and the oil pump during the period from when the engine starts to when the pressure reaches the threshold is higher than the rotational speed of the oil pump after the pressure becomes equal to or greater than the threshold value.

In this configuration, the internal combustion engine is equipped with a hydraulic variable valve mechanism that changes the valve timing of engine valves such as intake valves and exhaust valves, and the variable valve mechanism is driven by hydraulic oil fed from an oil pump. be done. Since a certain amount of hydraulic pressure is required to drive this variable valve mechanism, the variable valve mechanism is driven when the pressure of hydraulic oil fed from the oil pump is equal to or higher than a specified threshold.

Here, when the operation of the internal combustion engine is stopped and the driving of the oil pump is stopped, hydraulic oil is discharged from the variable valve mechanism. Therefore, until the oil pump starts to be driven when the engine is started and the variable valve mechanism is filled with hydraulic oil, the pressure of the hydraulic oil fed from the oil pump cannot be increased to or above the above threshold value. A delay time occurs between the start of the engine and the time when the variable valve mechanism becomes drivable.

In this regard, in the same configuration, by executing the speed increasing process, the rotation speed of the oil pump is increased from the start of the engine until the pressure of the hydraulic oil reaches the threshold value. The amount of hydraulic oil fed from the oil pump per unit increases. Therefore, compared to the case where the speed increasing process is not executed, the time from the start of the engine until the pressure of the hydraulic oil reaches the threshold is shortened, thereby shortening the delay time. .

In the above configuration, the speed increasing process is executed until the cumulative number of rotations of the oil pump after the start of the engine becomes equal to or greater than a specified cumulative threshold, and the operation stop time of the internal combustion engine before the engine is started. and a control device for an internal combustion engine that executes a threshold value setting process for setting the integrated threshold value based on the cooling water temperature of the internal combustion engine when the engine is started.

As the number of rotations of the oil pump after the start of the engine increases, the total amount of hydraulic oil fed from the oil pump to the variable valve mechanism increases. Therefore, whether or not the hydraulic oil pressure has reached the above-described threshold value due to the filling of the variable valve mechanism with hydraulic oil after the engine starts is determined by the cumulative number of rotations of the oil pump after the engine starts can be determined based on Here, the cumulative number of revolutions at which it can be determined that the pressure of hydraulic fluid has reached the threshold value increases as the amount of hydraulic fluid that has escaped from the variable valve mechanism during stoppage of operation before starting the engine increases. The amount of hydraulic fluid that escapes from the variable valve mechanism increases as the operation stop time of the internal combustion engine increases before the engine starts. Further, the amount of hydraulic oil that escapes from the variable valve mechanism increases as the temperature of the cooling water at engine start-up is low and the viscosity of the hydraulic oil at shutdown is high.

Therefore, in the same configuration, the speed increasing process is executed until the cumulative number of rotations reaches or exceeds a specified cumulative threshold. I set it based on the water temperature. Therefore, since the integration threshold value is set according to the amount of hydraulic oil that has escaped from the variable valve mechanism during operation stop before starting the engine, the variable valve mechanism is fully charged with hydraulic oil and starts operation. It becomes possible to appropriately determine that the oil pressure has reached the threshold based on the cumulative number of rotations. In addition, in the same configuration, it is possible to determine that the pressure of the hydraulic oil has reached the threshold after the engine is started without detecting the pressure of the hydraulic oil fed to the variable valve mechanism. Even an internal combustion engine that does not have such a sensor for detecting the pressure of hydraulic fluid can perform the above-described acceleration process. Incidentally, if the oil pump is of a type that is rotationally driven by the crankshaft, the cumulative number of rotations of the crankshaft 34 after the start of the engine can be used as the cumulative number of rotations of the oil pump.

In the above configuration, the speed increasing process is executed until the elapsed time after the engine start becomes equal to or greater than a specified time threshold, and the operation stop time of the internal combustion engine before engine start and the internal combustion engine at the time of engine start. A control device for an internal combustion engine that executes a threshold setting process for setting the time threshold based on the cooling water temperature of .

Since the total amount of hydraulic oil fed from the oil pump to the variable valve mechanism increases as the elapsed time after the engine starts increases, the variable valve mechanism is filled with hydraulic oil after the engine starts. Whether or not the hydraulic oil pressure has reached the threshold value can be determined based on the elapsed time after the engine is started. Here, the elapsed time during which it can be determined that the pressure of hydraulic fluid has reached the threshold increases as the amount of hydraulic fluid that has escaped from the variable valve mechanism during stoppage of operation before starting the engine increases. The amount of hydraulic fluid that escapes from the variable valve mechanism increases as the operation stop time of the internal combustion engine increases before the engine starts. Further, the amount of hydraulic oil that escapes from the variable valve mechanism increases as the temperature of the cooling water at engine start-up is low and the viscosity of the hydraulic oil at shutdown is high.

Therefore, in the same configuration, the above speed increasing process is executed until the elapsed time after the engine starts becomes equal to or greater than a specified time threshold. It is set based on the cooling water temperature in Therefore, since the time threshold value is set according to the amount of hydraulic oil that has escaped from the variable valve mechanism during shutdown before starting the engine, the variable valve mechanism is fully charged with hydraulic oil and operated. Whether or not the oil pressure has reached the threshold value can be appropriately determined based on the elapsed time after the engine is started. In addition, in the same configuration, it is possible to determine that the pressure of the hydraulic oil has reached the threshold after the engine is started without detecting the pressure of the hydraulic oil fed to the variable valve mechanism. Even an internal combustion engine that does not have such a sensor for detecting the pressure of hydraulic fluid can perform the above-described acceleration process.

DESCRIPTION OF SYMBOLS 10... Internal combustion engine 10H... Cylinder head 11... Intake passage 12... Intake port 13... Surge tank 14... Throttle valve 14g... Outer peripheral edge of throttle valve 14w... Water jacket 15... Intake valve 16... Intake camshaft 17 Variable valve mechanism 21 Exhaust passage 22 Exhaust port 23 Three-way catalyst (catalyst) 25 Exhaust valve 26 Exhaust camshaft 30 Combustion chamber 31 Fuel injection Valve 32 Spark plug 33 Piston 34 Crankshaft 40 Planetary gear mechanism 41 Sun gear 42 Ring gear 44 Carrier 50 Reduction mechanism 60 Drive shaft 61 Differential gear 62 Drive wheel 71 First motor generator (first MG) 72 Second motor generator (second MG) 78 Battery 80 Crank angle sensor 81 Cam angle sensor 82 Air flow meter 83 Water temperature Sensors 84 Outside air temperature sensor 85 Vehicle speed sensor 86 Accelerator position sensor 87 Pressure sensor 88 Front sensor 89 Rear sensor 90 Oil pump 100 Control device 110 Central processing unit (CPU ), 120... memory, 200... PCU, 500... hybrid vehicle (vehicle).

Claims (9)

Applied to an internal combustion engine comprising an intake valve for opening and closing an intake port provided in each of a plurality of cylinders, and a fuel injection valve for injecting fuel into the intake port, and increasing the fuel injection amount to a prescribed increase value when the engine is started A control device that increases the amount at start-up by increasing the amount at
With respect to the total amount of fuel injection amount increase during execution of the fuel injection amount at startup, the total amount of the cylinder whose intake valve was closed during operation stop before engine start is executing a total amount adjustment process that increases the total amount of the cylinder that was in the open state ,
executing a process of attenuating the increase value and ending the increase at startup when a prescribed attenuation start time elapses after starting the increase at startup;
The total amount adjustment process executes a process of increasing the total amount by lengthening the attenuation start time.
A control device for an internal combustion engine. Applied to an internal combustion engine comprising an intake valve for opening and closing an intake port provided in each of a plurality of cylinders, and a fuel injection valve for injecting fuel into the intake port, and increasing the fuel injection amount to a prescribed increase value when the engine is started A control device that increases the amount at start-up by increasing the amount at
With respect to the total amount of fuel injection amount increase during execution of the fuel injection amount at startup, the total amount of the cylinder whose intake valve was closed during operation stop before engine start is executing a total amount adjustment process that increases the total amount of the cylinder that was in the open state ,
After starting the increase at startup, performing a process of attenuating the increase value at a prescribed attenuation speed and ending the increase at startup;
The total amount adjustment process executes a process of increasing the total amount by slowing the attenuation speed.
A control device for an internal combustion engine. Applied to an internal combustion engine comprising an intake valve for opening and closing an intake port provided in each of a plurality of cylinders, and a fuel injection valve for injecting fuel into the intake port, and increasing the fuel injection amount to a prescribed increase value when the engine is started A control device that increases the amount at start-up by increasing the amount at
With respect to the total amount of fuel injection amount increase during execution of the fuel injection amount at startup, the total amount of the cylinder whose intake valve was closed during operation stop before engine start is executing a total amount adjustment process that increases the total amount of the cylinder that was in the open state ,
The internal combustion engine is mounted on a vehicle having an internal combustion engine and an electric motor as a prime mover, and an exhaust passage of the internal combustion engine is provided with a catalyst for purifying exhaust gas,
When a request to stop the operation of the internal combustion engine is generated during the execution of the fuel increase at startup, a stop delay process is executed to delay the operation stop of the internal combustion engine until the atmosphere of the catalyst becomes stoichiometric,
If the vehicle speed of the vehicle when the operation stop request is generated is equal to or less than a prescribed threshold value, a process for stopping the operation of the internal combustion engine is executed without executing the stop delay process.
A control device for an internal combustion engine. The internal combustion engine includes a sensor that detects the atmosphere of the catalyst,
The stop delay processing determines whether or not the atmosphere of the catalyst is in a stoichiometric state based on the detection value of the sensor. and executing a process of stopping the operation of the internal combustion engine after an integrated amount of air, which is an integrated value of the amount of air drawn into the internal combustion engine after the end of the increase in amount at startup, becomes equal to or greater than a specified air amount threshold. The control device for an internal combustion engine according to claim 3 . 5. The control device for an internal combustion engine according to claim 4 , wherein the air amount threshold value is variably set so as to increase as the total amount increases. 6. The process of increasing the total amount of each cylinder in the total amount adjustment process as the operation stop time, which is the time during which the operation of the internal combustion engine is stopped before starting the engine, increases. A control device for an internal combustion engine according to claim 1 . The control of the internal combustion engine according to any one of claims 1 to 6, wherein the total amount adjustment process increases the total amount of each cylinder as the cooling water temperature of the internal combustion engine at the start of engine start is lower. Device. operation stop time of the internal combustion engine before engine start, cooling water temperature of the internal combustion engine during stop operation, and the state of the intake valve of each cylinder during stop operation. In addition to executing a valve temperature estimation process that calculates the temperature of the intake valve,
The valve temperature estimating process is performed so that the temperature of the intake valve that is in a closed state during the suspension of operation is lower than the temperature of the intake valve that is in an open state during the suspension of operation. Execute the process to calculate the temperature,
In the total amount adjustment process, the total amount of the cylinder with the low temperature of the intake valve during shutdown is made larger than the total amount of the cylinder with the high temperature of the intake valve during shutdown. 4. The control device for an internal combustion engine according to any one of items 1 to 3 . The control device for an internal combustion engine according to any one of claims 1 to 8, wherein the total amount adjusting process executes a process of increasing the total amount by increasing the increase value.

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