Abstract: In internal combustion engines, certain hydraulically or electrically powered components can be used, such as engine intake/exhaust valves and fuel injector plungers. In many cases, these components are desirably placed in a predetermined condition prior to starting the engine, in many cases by way of a spring or other biasing devices that biased the components to the predetermined condition. In other cases, however, hydraulic pressure or electromagnetic force is used to maintain the components in the predetermined condition. In hydraulic systems, however, leakage and thermal contraction can lead to pressure loss during period of non-operation, thereby allowing the components to move away from the predetermined condition. Similar concerns arise with the use of residual electromagnetic force, which can decay over time. In the case of intake/exhaust valves, for example, such undesired movement can lead to a potential collision between the valves and the engine piston during starting.

Abstract: The present invention provides a method and apparatus for controlling an actuation of a compression brake associated with a combustion engine. The engine includes a fluid circuit for delivering a fluid to the compression brake. The engine also includes a cylinder having an associated exhaust valve. The method includes the steps of establishing a desired timing of an actuation of the brake, determining an air pressure of the engine, and determining a desired fluid pressure in response to the timing and the air pressure.