Systems and methods for managing excessive intake flow path pressure and counter flow are implemented to support enhanced engine braking applications, such as 2-stroke or 1.5-stroke engine braking implementations where the intake flow path may be exposed to excessive transient pressures in the combustion chamber during activation or deactivation of an engine brake. Intake throttle, exhaust gas recirculation (EGR) valve, intake manifold blow-off valve, compressor bypass valve, exhaust throttle, turbocharger geometry or turbocharger waste gate may be controlled to effectuate counter flow management separately or in combination. Excessive transient conditions may also be prevented or managed by sequential valve motion in which brake motion activation occurs first and then exhaust valve main event deactivation occurs second. Delay between brake activation and main event deactivation may be facilitated using mechanical and/or hydraulic implements as well as electronically.

An internal combustion engine system includes an engine with a plurality of pistons housed in respective ones of a plurality of cylinders, an air intake system to provide air to the plurality of cylinders through respective ones of a plurality of intake valves, an exhaust system to release exhaust gas from the plurality of cylinders through respective one of a plurality of exhaust valves. A valve train is provided for cylinder deactivation of a first part of the plurality of cylinders and compression release braking on a second part of the plurality of cylinders.

A rocker arm assembly operable in a first mode and a second mode, the rocker arm assembly selectively opening first and second engine valves based on rotation of a cam shaft having a first cam lobe and a second cam lobe, includes: a rocker shaft; a first rocker arm assembly having a first rocker arm that receives the rocker shaft and rotates around the rocker shaft in the first mode based on engagement with the first cam lobe; a second rocker arm assembly having a second rocker arm that receives the rocker shaft and rotates around the rocker shaft and selectively act on one of the first and second engine valves in the second mode based on selective engagement with the second cam lobe; and a biasing assembly that cooperates with the second rocker arm to bias the second rocker arm to a neutral position.

A castellation assembly comprises a lost motion spring assembly, an upper castellation piece, and a lower castellation piece. A spring hat comprises a crown, a pin hole through the crown, and a brim. A lost motion spring is seated against the spring hat.

Upper castellation piece comprises a tubular body, an upper inner rim adjoining the brim, and upper castellation teeth. Lower castellation piece comprises a spring post extending up from a castellation body, the spring post passing through the lost motion spring, and through the pin hole. Lower castellation teeth extend from the castellation body. The lost motion spring is biased against the castellation body to lift the upper inner rim by the brim. A lash screw can house the spring post so that the spring post terminates inside the lash screw. A rocker arm is an example of a castellation assembly installation.

Disclosured herein are apparatus and methods relating to combustion engines. In an example, a combustion engine includes a head and a rocker assembly. The rocker assembly including: a rocker shaft including therein a pressure reservoir, a pedestal support adapted to be fastened to the head and sized and structured to support the rocker shaft, a rocker lever pivotally supported by the rocker shaft, and a hydraulic engine brake mechanism within the rocker lever including a hydraulic control valve configured to selectively actuate an exhaust valve of the combustion engine.

An engine valve actuation system includes engine braking rocker arms each having a hydraulically actuated switch, and an electrohydraulic control system including an actuation fluid supply, an electrically actuated valve adjustable to vary a pressure of actuation fluid supplied from the actuation fluid supply to the hydraulically actuated switches, and an engine braking control unit. The engine braking control unit is structured to command adjusting the electrically actuated valve to adjust the hydraulically actuated switch in each of the engine braking rocker arms at a switching window timing that is varied from engine braking cycle to engine braking cycle to distribute hard handoffs among the engine braking rocker arms.

A valve actuation system comprises at least one main rocker arm operatively connected to a first engine valve, the at least one main rocker arm configured to receive at least main valve actuation motions. A second rocker arm is operatively connected to a second engine valve, the second rocker arm being configured to receive first auxiliary valve actuation motions. The second rocker arm further comprising a hydraulically-controlled first actuator that can selectively couple or decouple the second rocker arm and the second engine valve thereby permitting or preventing conveyance of the first auxiliary valve actuation motions from the second rocker arm to the second engine valve. A one-way coupling mechanism disposed between the at least one main rocker arm and the second rocker arm permits valve actuation motions to be transferred from the at least one main rocker arm to the second rocker arm, but not vice versa.

A compression release type engine brake includes a first opening unit and a second opening unit each including an exhaust rocker arm, an adjusting screw provided at an end portion of the exhaust rocker arm, a brake module in which brake oil is selectively and a brake piston mount portion is formed therein, a brake piston which is selectively protruded according to the oil supply inside the brake module, a reset member selectively exhausting the oil in the brake module, and a valve bridge connected to the brake piston and provided with an exhaust valve, and wherein a rocker arm protrusion is formed in the exhaust rocker arm of at least one of the first opening unit and the second opening unit, and the shaft spring presses the rocker arm protrusion and adjusts a distance between the first opening unit and the second opening unit.

Hydraulic systems in an engine valvetrain having lost motion and/or braking hydraulic circuits are provided with a conditioning circuit that may include a supplemental supply passage, which provides continuous and supplemental supply of hydraulic fluid from a supply source to the braking and lost motion circuits, as well as a venting of the circuits to ambient, such that the hydraulic fluid in these circuits is kept in a refreshed and conditioned state without air contamination. A vented three-way solenoid valve may be utilized. The supplemental supply passage may be provided at various locations in the valvetrain and in the engine head environment. The supplemental supply passage may include flow and pressure control devices to control the flow of the supplemental supply of hydraulic fluid.

A type II valve train assembly that selectively opens first and second intake valves and first and second exhaust valves is provided. The valve train assembly includes an intake rocker arm assembly and an exhaust rocker arm assembly. The valve train assembly is configurable for operation in any combination of activated and deactivated states of engine braking and cylinder deactivation. The exhaust rocker arm assembly includes a first exhaust rocker arm, a second exhaust rocker arm and an engine brake exhaust rocker arm. A first exhaust HLA is associated with the first exhaust rocker arm. A second exhaust HLA is associated with the second exhaust valve. An exhaust actuation assembly selectively actuates to alter travel of the first and second exhaust HLA's to change a state of cylinder deactivation between activated and deactivated.