초록 ▼

An exhaust valve early-closure control brings about blowback of exhaust gas into an intake system. However, if the exhaust valve early-closure control is executed, for example, during a first idle operation immediately following the startup of the engine, or the like, the amount of blowback exhaust

An exhaust valve early-closure control brings about blowback of exhaust gas into an intake system. However, if the exhaust valve early-closure control is executed, for example, during a first idle operation immediately following the startup of the engine, or the like, the amount of blowback exhaust gas becomes excessively large. Therefore, when the post-startup increase amount has decreased to or below a lower-limit criterion value, the ECU prohibits the exhaust valve early-closure control, and changes the control to a usual valve timing control. As a result, during a period during which the combustion state has a stability margin and the amount of emission of HCs and the like is large, the exhaust emission quality can be bettered by the exhaust valve early-closure control. Besides, when the post-startup increase amount has decreased, the combustion state can be stabilized by prohibiting the exhaust valve early-closure control.

대표청구항 ▼

1. An internal combustion engine control device comprising: a variable valve mechanism that variably sets valve timing of at least one of an intake valve and an exhaust valve of an internal combustion engine;a blowback generation device that causes blowback of exhaust gas from a cylinder toward an i

1. An internal combustion engine control device comprising: a variable valve mechanism that variably sets valve timing of at least one of an intake valve and an exhaust valve of an internal combustion engine;a blowback generation device that causes blowback of exhaust gas from a cylinder toward an intake system through control of the valve timing by the variable valve mechanism;a usual valve timing control device that, when the blowback generation device is not in operation, controls the valve timing while having a less amount of blowback exhaust gas than the blowback generation device by operating the variable valve mechanism according to an operation state of the internal combustion engine;an injection amount increase device that calculates an increase in injection amount for keeping fuel injection amount of the internal combustion engine in an increased state, and decreases the increase in injection amount as time elapses; anda blowback prohibition device that prohibits operation of the blowback generation device when the increase in injection amount decreases to or below a lower-limit criterion value. 2. The control device according to claim 1, wherein the blowback generation device causes blowback of exhaust gas from the cylinder toward the intake system by controlling an exhaust valve closure timing of the exhaust valve in crank angle to an advanced side from the timing that corresponds to an intake top dead center. 3. The control device according to claim 1, wherein the blowback prohibition device prohibits operation of the blowback generation device when an acceleration request for the internal combustion engine is detected. 4. The control device according to claim 1, wherein the blowback generation device brings about a minus overlap period during which the intake valve and the exhaust valve are in a closed state near an intake top dead center, and the usual valve timing control device makes the minus overlap period shorter than the blowback generation device. 5. The control device according to claim 1, wherein the lower-limit criterion value is set according to such a minimum increase in injection amount that a combustion state of the internal combustion engine is able to be stabilized even when blowback of exhaust gas occurs. 6. The control device according to claim 1, wherein the blowback prohibition device prohibits operation of the blowback generation device when generation of an acceleration request for the internal combustion engine is expected. 7. The control device according to claim 6, further comprising an idling detection device that outputs an idle signal when an accelerator operation device that is operated to accelerate or decelerate the internal combustion engine is in a non-operated state, whereinthe blowback prohibition device expects generation of the acceleration request when output of the idling detection device changes from the idle signal to a non-idle signal. 8. The control device according to claim 6, further comprising a shift position detection device that detects whether a shift operation device that is operated to perform transmission speed shift operation of the internal combustion engine is present at a neutral position or a drive operation position, whereinthe blowback prohibition device expects generation of the acceleration request when the shift operation device is switched from the neutral position to the drive operation position. 9. The control device according to claim 1, wherein the blowback generation device implements an exhaust valve early-closure control of advancing a closure timing of the exhaust valve by operating the variable valve mechanism so as to bring about blowback of exhaust gas in the intake system, and the control device further comprisesa rotation-corresponding correction device that corrects the closure timing of the exhaust valve set by the exhaust valve early-closure control according to engine rotation speed during an idle operation of the internal combustion engine. 10. The control device according to claim 9, wherein the rotation-corresponding correction device retards the closure timing of the exhaust valve further if the engine rotation speed during the idle operation is higher. 11. The control device according to claim 9, further comprising: a temperature detection device that detects a temperature state of the internal combustion engine; anda temperature-corresponding correction device that retards the closure timing of the exhaust valve further if the temperature state of the idle operation is higher. 12. The control device according to claim 1, further comprising an outside air temperature acquisition device that acquires temperature of an outside air, whereinthe blowback generation device determines, based on at least the outside air temperature, whether or not to execute a minus valve overlap period formation control of controlling the variable valve mechanism so as to form a minus valve overlap period that is a period during which both the intake valve and the exhaust valve remain closed, and executes the minus valve overlap period formation control if it is determined that the minus valve overlap period formation control is to be executed. 13. The control device according to claim 12, wherein the blowback generation device executes as the minus valve overlap period formation control a first control of determining the minus valve overlap period in accordance with a first pattern if a predetermined condition that does not include a condition that concerns the outside air temperature is satisfied, and the blowback generation device executes as the minus valve overlap period formation control a second control of determining the minus valve overlap period in accordance with a second pattern if the predetermined condition is not satisfied and the outside air temperature is lower than a first threshold value. 14. The control device according to claim 13, further comprising: a temperature detection device that acquires temperature of a cooling liquid of the internal combustion engine, whereinthe blowback generation device executes the second control in a case where the predetermined condition is not satisfied, and where the outside air temperature is lower than the first threshold value, and where the cooling liquid temperature is lower than a second threshold value. 15. The control device according to claim 14, wherein the blowback generation device executes the second control also in a case where the predetermined condition is not satisfied, and where the outside air temperature is lower than the first threshold value, and where the cooling liquid temperature is higher than or equal to the second threshold value, and where the cooling liquid temperature has a falling tendency. 16. The control device according to claim 12, wherein the blowback generation device determines a range of value of a parameter representing the operation state of the internal combustion engine so that the range is larger in a case where the outside air temperature is a second temperature than in a case where the outside air temperature is a first temperature that is higher than the second temperature, and executes the minus valve overlap period formation control if the value of the parameter is within the range. 17. The control device according to claim 16, wherein the blowback generation device determines the range to be the first range if the outside air temperature is higher than or equal to a first threshold value, and the blowback generation device determines the range to be a second range that is larger than the first range if the outside air temperature is lower than the first threshold value. 18. The control device according to claim 17, further comprising: a temperature detection device that acquires temperature of a cooling liquid of the internal combustion engine, whereinthe blowback generation device determines the range to be the second range in a case where the outside air temperature is lower than the first threshold value and where the cooling liquid temperature is lower than a second threshold value. 19. The control device according to claim 18, wherein the blowback generation device determines the range to be the second range also in a case where the outside air temperature is lower than the first threshold value, and where the cooling liquid temperature is higher than or equal to the second threshold value, and where the cooling liquid temperature has a falling tendency. 20. The control device according to claim 1, further comprising: a negative pressure acquisition device that acquires intake negative pressure of the internal combustion engine;a negative pressure determination device that determines whether or not there is a sufficient intake negative pressure for a brake device when the internal combustion engine enters a decelerating state; anda standard timing setting device that sets the valve timing to a standard timing adapted for a time of deceleration via the variable valve mechanism when it is determined by the negative pressure determination device that the intake negative pressure is sufficient, whereinwhen it is determined by the negative pressure determination device that the intake negative pressure is insufficient, the blowback generation device makes the amount of blowback exhaust gas to the intake system less than the amount of blowback that is caused by the standard timing, by changing the valve timing via the variable valve mechanism. 21. The control device according to claim 20, wherein the standard timing is an initial valve timing that is used as an initial setting of the valve timing when the variable valve mechanism starts to operate. 22. The control device according to claim 20, further comprising: a memory device in which the valve timing that minimizes the amount of blowback exhaust gas is pre-stored as a target timing, whereinthe blowback generation device sets the valve timing to the target timing when the amount of blowback exhaust gas is to be decreased. 23. The control device according to claim 20, further comprising: a return device that returns the valve timing to the standard timing when a sufficient intake negative pressure occurs during operation of the blowback generation device. 24. The control device according to claim 20, wherein the standard timing provides a minus overlap period during which both the intake valve and the exhaust valve are in a closed state, and the blowback generation device decreases the amount of blowback exhaust gas by shortening the minus overlap period. 25. The control device according to claim 24, wherein the blowback generation device shortens the minus overlap period by retarding the valve timing of the exhaust valve. 26. The control device according to claim 24, wherein the blowback generation device shortens the minus overlap period by advancing the valve timing of the intake valve.