A valvetrain assembly comprises a deactivatable rocker arm where a pushrod is configured to transfer a valve lift profile through to a valve end to a valve or valve bridge. A castellation assembly in a carrier and alternative two-piece rocker arm assemblies with rotary or linear actuators are shown for deactivating the transfer of the valve lift profile.

A method for controlling vehicle speed comprises selecting an engine speed profile for a vehicle. Road grade data is received and processed to determine a road grade for the vehicle. Vehicle speed data is received and processed to determine a vehicle speed for the vehicle. A cylinder deactivation mode for a valvetrain of a multi-cylinder engine of the vehicle is selected. The cylinder deactivation mode comprises deactivating one or more intake valve, exhaust valve, and fuel injection for one or more cylinder of the multi-cylinder engine. The selected cylinder deactivation mode provides a controlled deviation from the selected engine speed profile at the road grade and vehicle speed.

A latch assembly comprises a latch pin configured to reciprocate in a latch bore. The latch pin comprises a main body comprising a first plug end, a second plug end, and a clearance between the first plug end and the second plug end. The latch pin is configured to selectively move in the latch bore. A rocker arm assembly can comprise the latch assembly. An outer arm can be configured to rotate about a rocker shaft and comprise the latch bore. An inner arm can at least be partially disposed within the outer arm and configured to rotate. When the latch pin is in the activated position, the inner arm is configured to transfer force to the outer arm via the latch pin. When the latch pin is in the deactivated position, the inner arm is configured to move in the clearance and in the lost motion gap.

An overhead cam engine system comprises a rotating overhead exhaust cam rail comprising a plurality of exhaust lobes. A first switching roller finger follower actuates a first exhaust valve, and is configured to switch between a first lift profile and a second lift profile. A second switching roller finger follower is coupled to actuate a second exhaust valve, and is configured to switch between a third lift profile and a fourth lift profile. The third and fourth lift profile are different than the first and second lift profile. An actuation assembly is connected to switch the first switching roller finger follower and the second switching roller finger follower to select between at least three exhaust lift modes to open and close the first exhaust valve and the second exhaust valve using combinations of the first, second, third and fourth lift profiles.

A rocker arm assembly can comprise a cam side rocker arm portion configured to selectively rotate about a pivot location. The cam side rocker arm portion can comprise a first socket above the pivot location, and a cam end configured to receive a lift profile from a cam lobe. A valve side rocker arm portion can be configured to rotate about the pivot location relative to the cam side rocker arm portion. The valve side rocker arm portion can comprise a second socket above the pivot location. A lost motion spring can span between the first socket and the second socket.

Methods and systems are provided for a diagnostic routine of a variable displacement engine (VDE) of a vehicle to detect non-deactivated valves of deactivated cylinders due to a degraded valve deactivation mechanism. In one example, a method comprises, during operation of the VDE with one or more cylinders of the VDE deactivated, calculating a variation in a fast-sampled signal outputted by one or more exhaust gas oxygen (EGO) sensors of the VDE over a plurality of engine cycles; determining that the variation is greater than the threshold variation; and in response, indicating that valves of the one or more cylinders are not deactivated. A second method comprises estimating a throttle air flow rate and an engine air flow rate of the VDE; and indicating non-deactivated valves of one or more deactivated cylinders if the throttle air flow rate exceeds the engine air flow rate by a threshold.

A valve actuation system comprises a valve actuation motion source configured to provide main and auxiliary valve actuation motions for actuating at least one engine valve via a valve actuation load path. A lost motion subtracting mechanism is arranged in a valve bridge and configured, in a first default operating state, to convey at least the main valve actuation motion and configured, in a first activated state, to lose the main valve actuation motion and the auxiliary valve actuation motion. Additionally, a lost motion adding mechanism is arranged in a rocker arm and configured, in a second default operating state, to lose the auxiliary valve actuation motion and configured, in a second activated state, to convey the auxiliary valve actuation motion, wherein the lost motion adding mechanism is parallel with the lost motion subtracting mechanism in the valve actuation load path at least during the second activated state.

A switching rocker arm comprises an outer arm having a pair of integrally formed axles extending outwardly therefrom and an inner arm pivotally secured to the outer arm. A is latch slidably connected to the outer arm and is configured to selectively extend to engage the inner arm. An inner roller is configured on the inner arm, and a pair of outer rollers is mounted on the respective integrally formed axles on the outer arm. A rocker arm for variable valve lift comprises an outer arm comprising outer arm portions, rollers mounted in a cantilevered manner to the outer arm portions, and an inner arm seated between the outer arm portions, the inner arm comprising an inner roller. A pivot axle connects the outer arm and the inner arm. The inner arm and the outer arm are pivotable with respect to one another about the pivot axle.

A rocker arm can comprise a first outer arm and a second outer arm joined by a pivot body. An actuatable latch mechanism is within the pivot body. An inner arm assembly comprises a latch arm. A first spring prop is on the inner arm assembly distal from the latch arm. An axle joins the inner arm assembly to pivot between the first outer arm and the second outer arm. A spring is biased against the first outer arm and against the first spring prop. The first spring prop can comprise a hooked end. Or, the first spring prop can extend laterally out from the rocker arm and parallel to the axle. The spring can comprise a one-piece spring comprising first and second coil springs connected by a lateral connector. Or, two separate torsion springs can comprising tangential spring ends extending at approximately 90 degrees.

A type III rocker arm assembly operable in a first mode and a second mode based on rotation of a cam shaft includes a rocker shaft and a first rocker arm assembly. The first rocker arm assembly receives the rocker shaft and is configured to rotate around the rocker shaft in the first mode based on engagement with the first cam lobe. The first rocker arm assembly collectively comprises a valve side rocker arm, a cam side rocker arm and a latch pin. The valve side rocker arm defines a valve side rocker arm bore. The cam side rocker arm defines a cam side rocker arm bore. The latch pin assembly is received by the valve and cam side rocker arm bores and selectively couples the valve side rocker arm and the cam side rocker arm for concurrent movement in the first mode.