Abstract: An engine (10) has a hydraulic system (28) that serves both fuel injectors (22) and hydraulic actuators (40) of an engine brake that brakes the engine by controlling exhaust gas flow during engine braking. Pressure of the hydraulic fluid is set by an injection control strategy when a brake control pressure strategy is inactive. When the brake control pressure strategy is active, braking of the engine occurs when hydraulic fluid is delivered to the actuators. The brake control pressure strategy signals pressure of the hydraulic fluid supplied to the one or more actuators that is in excess of a pressure determined by a brake control pressure strategy. The brake control pressure strategy then limits pressure of the hydraulic fluid.

Abstract: In internal combustion engines that use hydraulic-fluid actuated fuel injectors, enhanced engine compression braking can be realized with simplified hydraulic control systems, by using fuel injector hydraulic fluid to open exhaust valves at or near the top of a compression stroke. Opening the exhaust valves at the top of a compression stroke wastes compressed gas to the atmosphere providing enhanced efficiency of engine compression braking. Using existing fuel injector high pressure fluid or engine oil to actuate a slave piston and thereby actuate the exhaust valve obviates the need for a separate, dedicated high-pressure oil delivery system for engine compression braking purposes.

Abstract: In internal combustion engines that use hydraulic-fluid actuated fuel injectors, enhanced engine compression braking can be realized with simplified hydraulic control systems, by using fuel injector hydraulic fluid to open exhaust valves at or near the top of a compression stroke. Opening the exhaust valves at the top of a compression stroke wastes compressed gas to the atmosphere providing enhanced efficiency of engine compression braking. Using existing fuel injector high pressure fluid or engine oil to actuate a slave piston and thereby actuate the exhaust valve obviates the need for a separate, dedicated high-pressure oil delivery system for engine compression braking purposes.