Variable valve actuator

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

• rotating a cam to move an intake valve between a first position to prevent a flow of fluid and a second position to allow a flow of fluid during the intake stroke of the piston, wherein the cam is mechanically connected to the intake valve;
• directing fluid through a bi-directional control valve and a fluid passageway to a fluid actuator associated with the intake valve after the intake valve is moved from the first position, wherein the fluid actuator is configured to selectively hold the intake valve at a position between the first position and the second position;
• actuating the bi-directional control valve to selectively prevent fluid from flowing through the fluid passageway from the fluid actuator to thereby prevent the intake valve from moving to the first position;
• and
• allowing a pressure in the fluid passageway to fall below a threshold pressure to allow a relief valve disposed in fluid communication with the fluid passageway to open and at least a portion of the fluid within the fluid passageway to drain to an external environment.

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, wherein the cam assembly is mechanically connected to the intake valve;
• a fluid actuator configured to selectively prevent the intake valve from moving to the first position, and further configured to selectively hold the intake valve at a position between the first position and the second position;
• a source of fluid in fluid communication with the fluid actuator;
• a bi-directional control valve configured to control a flow of fluid between the source of fluid and the fluid actuator;
• a fluid passageway connecting the directional control valve with the fluid actuator;
• an accumulator in fluid communication with the fluid passageway;
• a restrictive orifice disposed between the accumulator and the fluid passageway to restrict a flow of fluid between the accumulator and the fluid passageway;
• a relief valve in fluid communication with the fluid passageway and moveable between a closed position to prevent a flow of fluid therethrough and an open position to allow a flow of fluid therethrough,
• wherein the relief valve is actuated between the closed position and the open position based at least on a pressure in the fluid passageway,
• wherein the closed position of the relief valve allows the fluid to pass through the fluid passageway to actuate the fluid actuator, and
• wherein the open position of the relief valve allows at least a portion of the fluid in the fluid passageway to drain from the fluid passageway to an external environment.