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 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 combined exhaust and engine brake rocker arm assembly configured to selectively open first and second exhaust valves, includes a rocker arm body, an exhaust rocker arm assembly formed in the rocker arm body, and an engine brake rocker arm assembly formed in the rocker arm body and configured to operate in a collapse mode and a rigid mode. The exhaust rocker arm assembly is configured to selectively engage a valve bridge to open the first and second exhaust valves, and the engine brake rocker arm assembly is configured to selectively engage the valve bridge to open only the first exhaust valve.

Valve bridge systems include constraints and guides for managing bridge jump and other uncontrolled valve bridge motion during engine operation. Constraints may include an e-foot collar, an extended portion on the bridge, and a bridge brake pin. Guides may include valve stem tip lead-in chamfers surrounding the valve bridge valve pockets as well as a deflection surface on the bridge extended portion. Methods of configuring valve bridges may include configuring the valve step tip lead-in chamfers based on worst-case positions of the valve bridge defined by one or more or a combination of the constraints provided by the e-foot collar, extended portion and brake pin.

Valve bridge systems include constraints and guides for managing bridge jump and other uncontrolled valve bridge motion during engine operation. Constraints may include an e-foot collar, an extended portion on the bridge, and a bridge brake pin. Guides may include valve stem tip lead-in chamfers surrounding the valve bridge valve pockets as well as a deflection surface on the bridge extended portion. Methods of configuring valve bridges may include configuring the valve step tip lead-in chamfers based on worst-case positions of the valve bridge defined by one or more or a combination of the constraints provided by the e-foot collar, extended portion and brake pin.

An exhaust valve rocker arm assembly includes an exhaust rocker arm and a valve bridge operably associated with the rocker arm. The valve bridge includes a main body and a lever rotatably coupled to the main body. The main body is configured to engage the first exhaust valve, and the lever is configured to engage the second exhaust valve.

An exhaust valve rocker arm assembly includes an exhaust rocker arm and a valve bridge operably associated with the rocker arm. The valve bridge includes a main body and a lever rotatably coupled to the main body. The main body is configured to engage the first exhaust valve, and the lever is configured to engage the second exhaust valve.

Intake holes at the opposite ends are opened and closed by first intake valves. The middle intake hole is opened and closed by a second intake valve. A control device includes an intake variable valve device. First branch channels are connected to the intake holes and produce a normal tumble flow. A second branch channel is configured such that the flow rate of intake air passing through the middle intake hole is relatively greater on the side closer to the outer periphery of the combustion chamber. Where increasing the flow coefficient is given a higher priority, a three-valve drive mode is selected. Where the strength of the normal tumble flow is enhanced, a two-valve drive mode is selected. Where production of the normal tumble flow is reduced, a one-valve drive mode is selected.

A compression-release engine brake system operating an exhaust valve of an engine during a compression-release engine braking operation. The compression-release brake system comprises an exhaust rocker arm and a brake reset device disposed in a reset bore formed in the exhaust rocker arm. The brake reset device comprises a reset check valve, a slider-piston slidably disposed in the reset bore and an external slider bias spring biasing the piston foot away from the brake reset device. The external slider bias spring is disposed outside the reset bore and around the piston-slider. The brake reset device permits pressurized hydraulic fluid to flow from a supply conduit to a reset conduit to supply a brake actuation piston when the reset check valve is open. The actuation piston extends and engages the exhaust valve toward the end of a compression stroke of the internal combustion engine, and the brake reset device resets.

A compression-release engine brake system operating an exhaust valve of an engine during a compression-release engine braking operation. The compression-release brake system comprises an exhaust rocker arm and a brake reset device disposed in a reset bore formed in the exhaust rocker arm. The brake reset device comprises a reset check valve, a slider-piston slidably disposed in the reset bore and an external slider bias spring biasing the piston foot away from the brake reset device. The external slider bias spring is disposed outside the reset bore and around the piston-slider. The brake reset device permits pressurized hydraulic fluid to flow from a supply conduit to a reset conduit to supply a brake actuation piston when the reset check valve is open. The actuation piston extends and engages the exhaust valve toward the end of a compression stroke of the internal combustion engine, and the brake reset device resets.