Abstract: Crank rocker variable valve timing (VVT) mechanisms are disclosed which are relatively compact and are applicable for operating individual or multiple valves. In an exemplary embodiment, an engine valve is driven by an oscillatable rocker cam that is actuated by a linkage driven by a rotary eccentric, preferably a rotary cam. The linkage is pivoted on a control member that is in turn pivotable about the axis of the rotary cam and angularly adjustable to vary the orientation of the rocker cam and thereby vary the valve lift and timing. The rotary cam may be carried on a camshaft. The oscillatable cam is pivoted on the rotational axis of the rotary cam. For some applications the rotary cam and follower could be replaced by a crank or eccentric driving a rocker arm. Numerous other variations in the arrangements are also possible.

Abstract: A planetary cam phaser includes an electric motor driven worm gear actuator for rotatably positioning a sun gear to vary the cam phase relative to the crankshaft of an associated engine. Preferably, the worm lead angle is made small to lock the actuator against back driving by camshaft generated forces so the phaser is actuated only by controlled motor movements. Alternatively, a return spring may be applied on the motor or worm shaft to return the phase to an initial position when the motor is de-energized or fails. In another version, the worm lead angle may be increased to permit limited back driving forces to drive the cam back to the initial position when the motor is off without the need for a return spring.

Abstract: A planetary cam phaser for varying the timing of an engine camshaft is provided with oppositely tapered teeth on the planet gear(s) and the mating ring and sun gears and biasing means for urging the mating gears axially into lash free engagement. The tapered teeth may be formed on constant pitch circles or on conical pitch circles of conical gears and the teeth of at least one of a pair of mating gears may be crowned to control loading and wear. The taper angles of the teeth and/or the conical pitch circles of the conical gears are preferably made small enough to avoid gear drive forces from developing gear separation forces greater than restraining friction forces.

Abstract: Integrated dilution control for diluting internal combustion engine intake air through control of relative timing between engine cylinder intake and exhaust valve events integrated with control of recirculation of engine exhaust gas through an external exhaust gas conduit with periodic recalibration of modeled relationships between dilution control parameters to correct for effects of dilution control system aging. Internal dilution provided through control of relative valve timing further may be maximized and external dilution provided through the external conduit minimized.