Engine valve actuation with handoff control between cooperative valve actuation motions
A valve actuation system comprises a first motion transfer mechanism operatively connected to a first valve actuation motion source and to the at least one engine valve, a second motion transfer mechanism operatively connected to a second valve actuation motion source; and a selectable coupling mechanism between the first and second motion transfer mechanisms. The coupling mechanism is operable in a first state where first valve actuation motions are conveyed to the at least one engine valve via the first motion transfer mechanism, and a second state where second valve actuation motions are additionally conveyed to the at least one engine valve via the second motion transfer mechanism, the coupling mechanism and the first motion transfer mechanism. During a handoff between the first and second valve actuation motions or vice versa, a difference in valve actuation velocities of the first and second valve actuation motions does not exceed a threshold.
1. A valve actuation system for actuating at least one engine valve, the valve actuation system comprising:
a first motion transfer mechanism operatively connected to a first valve actuation motion source and to the at least one engine valve;
a second motion transfer mechanism operatively connected to a second valve actuation motion source; and
a selectable coupling mechanism disposed between the first motion transfer mechanism and the second motion transfer mechanism,
wherein, when the selectable coupling mechanism is operated in a first state, first valve actuation motions provided by the first valve actuation motion source are conveyed to the at least one engine valve via the first motion transfer mechanism and, when the selectable coupling mechanism is operated in a second state, in addition to the first valve actuation motions conveyed via the first motion transfer mechanism, second valve actuation motions provided by the second valve actuation motion source are conveyed to the at least one engine valve via the second motion transfer mechanism, the coupling mechanism and the first motion transfer mechanism,
and wherein, during a handoff between the first valve actuation motions and the second valve actuation motions or vice versa, a difference in valve actuation velocities of the first valve actuation motions and the second valve actuation motions does not exceed a threshold.
2. The valve actuation system of claim 1 , the selectable coupling mechanism comprising a selectively extendable actuator, wherein the actuator is retracted during the first state and is extended during the second state.
3. The valve actuation system of claim 2 , wherein the difference in valve actuation velocities does not exceed the threshold during transition of the actuator from the first state to the second state.
4. The valve actuation system of claim 1 , wherein the first valve actuation motions comprise a main event profile.
5. The valve actuation system of claim 1 , wherein the handoff occurs during an opening segment of the first valve actuation motions.
6. The valve actuation system of claim 5 , wherein the second valve actuation motions comprise an early valve opening profile.
7. The valve actuation system of claim 6 , wherein the second valve actuation motions further comprise a valve actuation motion that does not give rise to a handoff with the first valve actuation motions.
8. The valve actuation system of claim 1 , wherein the handoff occurs during a closing segment of the first valve actuation motions.
9. The valve actuation system of claim 8 , wherein the second valve actuation motions comprise a late valve closing profile.
10. The valve actuation system of claim 9 , wherein the second valve actuation motions further comprise a valve actuation motion that does not give rise to a handoff with the first valve actuation motions.
11. The valve actuation system of claim 1 , wherein the at least one engine valve comprises an intake valve.
12. The valve actuation system of claim 1 , wherein the at least one engine valve comprises an exhaust valve.
13. The valve actuation system of claim 1 , wherein the first and second valve actuation motion sources are cam profiles.
14. The valve actuation system of claim 13 , wherein the opening or closing portion of the second valve actuation cam profile comprises a dwell or a single point with non-zero velocity and zero acceleration and jerk.
15. An internal combustion engine comprising the valve actuation system of claim 1 .
16. In an internal combustion engine comprising a first motion transfer mechanism operatively connected to a first valve actuation motion source and to at least one engine valve, a second motion transfer mechanism operatively connected to a second valve actuation motion source and a selectable coupling mechanism disposed between the first motion transfer mechanism and the second motion transfer mechanism, a method for actuating the at least one engine valve comprising:
operating the selectable coupling mechanism in a first state where first valve actuation motions provided by the first valve actuation motion source are conveyed to the at least one engine valve via the first motion transfer mechanism; and
operating the selectable coupling mechanism in a second state where, in addition to the first valve actuation motions conveyed via the first motion transfer mechanism, second valve actuation motions provided by the second valve actuation motion source are conveyed to the at least one engine valve via the second motion transfer mechanism, the coupling mechanism and the first motion transfer mechanism,
wherein, during a handoff between the first valve actuation motions and the second valve actuation motions or vice versa, a difference in valve actuation velocities of the first valve actuation motions and the second valve actuation motions does not exceed a threshold.