Valvetrain with variable valve actuation
A valvetrain assembly has valves each having a valve stem; a main camshaft with main cams, a main cam corresponding to each valve; main rocker arms each corresponding to a valve and having a valve stem actuation portion, a pivot axis parallel to the main cam shaft, and a main cam follower for following the corresponding main cam, wherein the valve stem actuation portion, pivot axis, and main cam follower are arranged along the main rocker arm length distanced from each other; an auxiliary cam on the main camshaft; an auxiliary cam follower for each auxiliary cam, following the auxiliary cam, wherein each auxiliary cam follower is movable on one main rocker arm between a first and second position; a latch on respective main rocker arm(s) for locking the auxiliary cam follower in the first position; and an auxiliary camshaft with a selector cam for each latch, controlling the latch.
1. A valvetrain assembly, comprising:
a first and a second valve each having a valve stem;
a main camshaft including at least one main cam corresponding to each of the first and second valves;
a first and second main rocker arm corresponding to the first and second valve, respectively, and each of the first and second main rocker arms including:
a valve stem actuation portion,
a pivot axis parallel to the main camshaft,
at least one main cam follower configured to follow a corresponding one of the at least one main cam, wherein the valve stem actuation portion, the pivot axis, and the at least one main cam follower are arranged along a length of the main rocker arm and at a distance from each other,
an auxiliary cam follower configured to follow an auxiliary cam arranged on the main camshaft, wherein the auxiliary cam follower is movably arranged on the main rocker arm between a first and a second position, and
a latch configured to lock the auxiliary cam follower in the first position;
wherein each latch corresponds to and is controlled by a selector cam arranged on an auxiliary camshaft,
wherein the first and the second valve both correspond to a single cylinder of a combustion engine, and
wherein each selector cam includes:
a first selector cam associated with the first valve, the first selector cam having a first profile, and
a second selector cam associated with the second valve, the second selector cam having a second profile different from the first profile.
2. The valvetrain assembly of claim 1 , each of the first and second main rocker arms further comprising:
a spring arranged between an auxiliary rocker arm and the main rocker arm, configured to urge the auxiliary cam follower to the first position.
3. The valvetrain assembly of claim 1 , wherein each latch includes a pin movable in a length of the main rocker arm such that:
a first end of the pin is engageable on an auxiliary rocker arm, and
the pin is urged with a second end in contact with the selector cam on the auxiliary camshaft.
4. The valvetrain assembly of claim 1 , wherein each valve stem actuation portion is arranged on a first end of the main rocker arm such that:
the pivot axis is arranged on a second end of the main rocker arm, and
the at least one main cam follower is arranged between the valve stem actuation portion and the pivot axis.
5. The valvetrain assembly of claim 4 , wherein each latch is arranged adjacent to the pivot axis.
6. The valvetrain assembly of claim 1 , further comprising:
an electric driver, configured to drive the auxiliary camshaft.
7. The valvetrain assembly of claim 1 , wherein each of the at least one main cams includes a first and a second identical, disc like, cam portion such that:
the auxiliary cam is arranged between the first and second identical cam portions, and
the at least one main cam follower includes a first and second main cam follower mirror-symmetrically arranged with respect to a rocker arm length.