Engine valve actuation system

A method of controlling an engine having a piston moveable through an intake stroke followed by an compression stroke, comprising:

• rotating a cam to move an intake valve between a first position to prevent a flow piston;
• directing fluid through a control valve to a fluid actuator associated with the intake valve when the intake valve is removed from the first position;
• actuating a directional control valve to selectively prevent fluid from flowing from the fluid actuator to thereby prevent the intake valve from moving to the first position during at least a portion of the compression stroke of the piston;
• sensing at least one operating parameter of the engine;
• and
• moving the control valve to a closed position to prevent fluid from flowing to the directional control valve and the fluid actuator based on the sensed operating parameter of the engine.

An engine, comprising:

• an engine block defining at least one cylinder and a cylinder head having at least one intake passageway leading to the at least one cylinder;
• at least one intake valve moveable between a first position to prevent a flow of fluid through the at least one intake passageway and a second position to allow a flow of fluid through the at least one intake passageway;
• a cam assembly connected to the intake valve to move the intake valve between the first position and the second position;
• a fluid actuator configured to selectively prevent the intake valve from moving to the first position;
• a first source of fluid in fluid communication with the fluid actuator;
• a second source of fluid configured to provide fluid having a pressure greater than the pressure of the fluid supplied by said first source of fluid;
• a directional control valve configured to control a flow of fluid between the source of fluid and the fluid actuator;
• a control valve disposed between either the first or second source of fluid and the directional control valve and moveable between a first position to prevent a flow of fluid between either the first or second source of fluid and the directional control valve and a second position to allow the flow of fluid from either the first or second source of fluid to the directional control valve;
• and
• a controller configured to move the control valve between the first and second positions based upon at least one operating parameter of the engine.