Fully flexible exhaust valve actuator control systems and methods

1. A system comprising:

a mode control module that selectively sets a desired ignition mode for an engine to one of a spark ignition (SI) mode and a homogenous charge compression ignition (HCCI) mode; and

a valve control module that, using a fully flexible valve actuator, incrementally adjusts closing timing of an exhaust valve at least twice in response to:

the desired ignition mode transitioning from the HCCI mode to the SI mode; and

the desired ignition mode transitioning from the SI mode to the HCCI mode.

2. The system of claim 1 wherein, in response to the desired ignition mode transitioning from the HCCI mode to the SI mode, the valve control module incrementally retards the closing timing of the exhaust valve at least twice using the fully flexible valve actuator, and

in response to the desired ignition mode transitioning from the SI mode to the HCCI mode, the valve control module incrementally advances the closing timing of the exhaust valve at least twice using the fully flexible valve actuator.

3. The system of claim 2 wherein the valve control module incrementally advances the closing timing of the exhaust valve by a first predetermined angle at least twice in response to the desired ignition mode transitioning from the SI mode to the HCCI mode.

4. The system of claim 2 wherein the valve control module incrementally retards the closing timing of the exhaust valve by a second predetermined angle at least twice in response to the desired ignition mode transitioning from the HCCI mode to the SI mode.

5. The system of claim 2 wherein the valve control module incrementally advances the closing timing of the exhaust valve by a first predetermined angle at least twice in response to the desired ignition mode transitioning from the SI mode to the HCCI mode, and

wherein the valve control module incrementally retards the closing timing of the exhaust valve by a second predetermined angle at least twice in response to the desired ignition mode transitioning from the HCCI mode to the SI mode.

6. The system of claim 5 wherein the first predetermined angle is equal to the second predetermined angle.

7. The system of claim 5 wherein the first predetermined angle is one of greater than and less than the second predetermined angle.

8. The system of claim 1 wherein the mode control module sets the desired ignition mode to one of the SI mode and the HCCI mode based on an engine load.

9. The system of claim 8 wherein the mode control module transitions the desired ignition mode from the HCCI mode to the SI mode in response to a determination that the engine load is greater than a first predetermined load, and

wherein the mode control module transitions the desired ignition mode from the SI mode to the HCCI mode in response to a determination that the engine load is less than a second predetermined load.

10. The system of claim 8 wherein the mode control module sets the desired ignition mode to one of the SI mode and the HCCI mode further based on an engine speed.

11. A method comprising:

selectively setting a desired ignition mode for an engine to one of a spark ignition (SI) mode and a homogenous charge compression ignition (HCCI) mode; and

using a fully flexible valve actuator, incrementally adjusting closing timing of an exhaust valve at least twice in response to:

the desired ignition mode transitioning from the HCCI mode to the SI mode; and

the desired ignition mode transitioning from the SI mode to the HCCI mode.

12. The method of claim 11 further comprising:

in response to the desired ignition mode transitioning from the HCCI mode to the SI mode, incrementally retarding the closing timing of the exhaust valve at least twice using the fully flexible valve actuator; and

in response to the desired ignition mode transitioning from the SI mode to the HCCI mode, incrementally advancing the closing timing of the exhaust valve at least twice using the fully flexible valve actuator.

13. The method of claim 12 further comprising incrementally advancing the closing timing of the exhaust valve by a first predetermined angle at least twice in response to the desired ignition mode transitioning from the SI mode to the HCCI mode.

14. The method of claim 12 further comprising incrementally retarding the closing timing of the exhaust valve by a second predetermined angle at least twice in response to the desired ignition mode transitioning from the HCCI mode to the SI mode.

15. The method of claim 12 further comprising:

incrementally advancing the closing timing of the exhaust valve by a first predetermined angle at least twice in response to the desired ignition mode transitioning from the SI mode to the HCCI mode; and

incrementally retarding the closing timing of the exhaust valve by a second predetermined angle at least twice in response to the desired ignition mode transitioning from the HCCI mode to the SI mode.

16. The method of claim 15 wherein the first predetermined angle is equal to the second predetermined angle.

17. The method of claim 15 wherein the first predetermined angle is one of greater than and less than the second predetermined angle.

18. The method of claim 11 further comprising setting the desired ignition mode to one of the SI mode and the HCCI mode based on an engine load.

19. The method of claim 18 further comprising:

transitioning the desired ignition mode from the HCCI mode to the SI mode in response to a determination that the engine load is greater than a first predetermined load; and

transitioning the desired ignition mode from the SI mode to the HCCI mode in response to a determination that the engine load is less than a second predetermined load.

20. The method of claim 18 further comprising setting the desired ignition mode to one of the SI mode and the HCCI mode further based on an engine speed.