Variable valve actuation system of internal combustion engine and control apparatus of internal combustion engine

1. A variable valve actuation system of an internal combustion engine employing a supercharging device for supercharging intake air into an engine cylinder, comprising:

a variable valve lift mechanism provided for variably controlling at least an intake-valve lift of engine valves;

a variable phase control mechanism provided for variably phase-shifting a central phase angle of a valve lift characteristic curve of at least one of intake and exhaust valves; and

a control system configured to electronically connected to the variable valve lift mechanism, the variable phase control mechanism, and the supercharging device, said control system programmed to perform the following,

(a) increasing the intake-valve lift by the variable valve lift mechanism when an accelerator opening increases from a small accelerator-opening condition; and

(b) increasing a valve overlap of the intake and exhaust valves by the variable phase control mechanism, while increasing a boost pressure by the supercharging device, after the intake-valve lift has been increased.

2. The variable valve actuation system as claimed in claim 1 , wherein:

the variable valve lift mechanism is configured to continuously vary at least the intake-valve lift; and

the variable valve lift mechanism continuously increases at least the intake-valve lift, when the accelerator opening increases from a minimum accelerator-opening condition.

3. The variable valve actuation system as claimed in claim 2 , wherein:

the internal combustion engine has an electronically-controlled throttle valve arranged upstream of the intake valve and located in an intake passage; and

the control system is further configured to control a throttle opening of the throttle valve to a throttle opening degree substantially corresponding to a full-throttle condition, when the accelerator opening increases from the minimum accelerator-opening condition.

4. The variable valve actuation system as claimed in claim 1 , wherein:

the valve overlap of the intake and exhaust valves is corrected and increased by the variable phase control mechanism, when the boost pressure, produced by the supercharging device, exceeds a predetermined boost pressure value.

5. The variable valve actuation system as claimed in claim 1 , wherein:

the supercharging device comprises a mechanical supercharging device, which is operated at an arbitrary timing; and

the mechanical supercharging device comes into operation, when the intake-valve lift reaches and exceeds a predetermined lift amount by the variable valve lift mechanism.

6. The variable valve actuation system as claimed in claim 1 , wherein:

the supercharging device comprises a mechanical supercharging device, which is operated at an arbitrary timing; and

the mechanical supercharging device comes into operation, when an engine speed reaches and exceeds a predetermined engine speed value.

7. The variable valve actuation system as claimed in claim 1 , wherein:

the supercharging device comprises a mechanical supercharging device, which is operated at an arbitrary timing; and

the mechanical supercharging device comes into operation, when the accelerator opening reaches and exceeds a predetermined accelerator opening.

8. The variable valve actuation system as claimed in claim 1 , wherein:

the supercharging device comprises a turbocharger, which is driven by kinetic energy of exhaust gases.

9. The variable valve actuation system as claimed in claim 1 , wherein:

the internal combustion engine is equipped with a catalytic converter located in an exhaust passage, and an air/fuel ratio sensor located in the exhaust passage for detecting an air/fuel mixture ratio; and

the valve overlap is corrected and decreased by the variable phase control mechanism, when the air/fuel mixture ratio, detected by the air/fuel ratio sensor, is lean and the engine is in a lean mode.

10. The variable valve actuation system as claimed in claim 1 , wherein:

the internal combustion engine is equipped with a catalytic converter located in an exhaust passage;

the internal combustion engine is an in-cylinder direct injection engine; and

the control system is adapted to be connected to an electronic fuel injection system for injecting fuel directly into the engine cylinder, after the exhaust valve has been closed.

11. A control apparatus of an internal combustion engine, comprising:

a controller programmed to perform the following,

(a) increasing an intake-valve lift by a variable valve lift mechanism, which is provided for variably controlling at least the intake-valve lift of engine valves, when starting from a vehicle stand-still state; and

(b) increasing a valve overlapping time period, during which intake and exhaust valves are both open, by a variable phase control mechanism, which is provided for variably phase-shifting a central phase angle of a valve lift characteristic curve of at least one of the intake and exhaust valves, while increasing a boost pressure of intake air introduced into an engine cylinder by a supercharging device, after the intake-valve lift has been increased.

12. The control apparatus as claimed in claim 11 , wherein:

the variable valve lift mechanism is configured to continuously vary at least the intake-valve lift; and

the variable valve lift mechanism variably controls at least the intake-valve lift in a manner so as to continuously increase the intake-valve lift, when starting from the vehicle stand-still state.

13. The control apparatus as claimed in claim 12 , wherein:

the internal combustion engine has an electronically-controlled throttle valve arranged upstream of the intake valve and located in an intake passage; and

the controller is further configured to control a throttle opening of the throttle valve to a throttle opening degree substantially corresponding to a full-throttle condition, when starting from the vehicle stand-still state.

14. The control apparatus as claimed in claim 11 , wherein:

the valve overlapping time period, during which the intake and exhaust valves are both open, is controlled and increased by the variable phase control mechanism, when the boost pressure, produced by the supercharging device, exceeds a predetermined boost pressure value.

15. The control apparatus as claimed in claim 11 , wherein:

the supercharging device comprises a mechanical supercharging device, which is operated at an arbitrary timing; and

the controller is further configured to shift the mechanical supercharging device to an operative state, when an engine speed reaches and exceeds a predetermined engine speed value.

16. The control apparatus as claimed in claim 11 , wherein:

the supercharging device comprises a mechanical supercharging device, which is operated at an arbitrary timing; and

the controller is further configured to shift the mechanical supercharging device to an operative state, when the accelerator opening reaches and exceeds a predetermined accelerator opening.

17. The control apparatus as claimed in claim 11 , wherein:

the supercharging device comprises a turbocharger, which is driven by kinetic energy of exhaust gases.

18. The control apparatus as claimed in claim 11 , wherein:

the internal combustion engine is equipped with a catalytic converter located in an exhaust passage, and an air/fuel ratio sensor located in the exhaust passage for detecting an air/fuel mixture ratio; and

the valve overlapping time period, during which the intake and exhaust valves are both open, is controlled and decreased by the variable phase control mechanism, when the air/fuel mixture ratio, detected by the air/fuel ratio sensor, is lean and the engine is in a lean mode.

19. The control apparatus as claimed in claim 11 , wherein:

the internal combustion engine is equipped with a catalytic converter located in an exhaust passage;

the internal combustion engine is an in-cylinder direct injection engine; and

the controller is adapted to be connected to an electronic fuel injection system for injecting fuel directly into the engine cylinder, after the exhaust valve has been closed.

20. A control apparatus of an internal combustion engine, comprising:

a controller programmed to perform the following,

(a) increasing an intake-valve lift by a variable valve lift mechanism, which is provided for variably controlling at least the intake-valve lift of engine valves, when an engine speed rises from an engine idling speed; and

(b) increasing a valve overlap between intake valve open timing of an intake valve and exhaust valve closure timing of an exhaust valve by a variable phase control mechanism, which is provided for variably phase-shifting a central phase angle of a valve lift characteristic curve of at least one of the intake and exhaust valves, while increasing a boost pressure of intake air introduced into an engine cylinder by a supercharging device, when the intake-valve lift reaches and exceeds a predetermined lift amount.