Valve actuation system for providing valve actuation motions for late/early intake valve closing and internal EGR
A valve actuation system comprises a first motion transfer mechanism operatively connected to a first valve actuation motion source providing at least main valve actuations to at least one intake engine valve. A second motion transfer mechanism is operatively connected to a second valve actuation motion source providing at least an LIVC and IEGR valve actuations. When a selectable coupling mechanism is operated in a first state, the main valve actuation is conveyed to the at least one intake engine valve via the first motion transfer mechanism. When the selectable coupling mechanism is operated in a second state, at least a portion of the main valve actuation is again conveyed to the at least one intake engine valve, and the LIVC and IEGR valve actuations are conveyed to the at least one intake engine valve via the second motion transfer mechanism, the coupling mechanism and the first motion transfer mechanism.
1 . A valve actuation system for actuating at least one intake 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 intake engine valve, wherein the first valve actuation motion source provides at least an early intake valve closing (EIVC) valve actuation motion;
a second motion transfer mechanism operatively connected to a second valve actuation motion source, wherein the second valve actuation motion source is configured to provide at least a main valve actuation motion and an internal exhaust gas recirculation (IEGR) valve actuation motion; 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, the EIVC valve actuation motion provided by the first valve actuation motion source is conveyed to the at least one intake engine valve via the first motion transfer mechanism and,
wherein, when the selectable coupling mechanism is operated in a second state, at least a portion of the EIVC valve actuation motion is conveyed to the at least one intake engine valve via the first motion transfer mechanism, and the main valve actuation motion and the IEGR valve actuation motion are conveyed to the at least one intake engine valve via the second motion transfer mechanism, the coupling mechanism and the first motion transfer mechanism.
2 . The valve actuation system of claim 1 , wherein the selectable coupling mechanism comprises a selectable hydraulic actuator and wherein the hydraulic actuator is retracted during the first state and is extended during the second state.
3 . The valve actuation system of claim 1 , wherein the selectable coupling mechanism comprises a selectable mechanical locking mechanism and wherein the mechanical locking mechanism is unlocked during the first state and is locked during the second state.
4 . The valve actuation system of claim 1 , wherein, when the selectable coupling mechanism is operated in the second state, a handoff occurs from the EIVC valve actuation motion to the main intake valve actuation motion.
5 . The valve actuation system of claim 1 , wherein the IEGR valve actuation motion does not give rise to a handoff with the EIVC valve actuation motion.
6 . An internal combustion engine comprising the valve actuation system of claim 1 .
7 . 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 intake 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 intake engine valve comprising:
operating the selectable coupling mechanism in a first state where at least an EIVC valve actuation motion provided by the first valve actuation motion source is conveyed to the at least one intake engine valve via the first motion transfer mechanism; and
operating the selectable coupling mechanism in a second state where, in addition to at least a portion of the EIVC valve actuation motion 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 intake engine valve via the second motion transfer mechanism, the coupling mechanism and the first motion transfer mechanism,
wherein the second valve actuation motions provided by the second valve actuation motion source comprise at least a main valve actuation motion and an internal exhaust gas recirculation (IEGR) valve actuation motion.