Engine valve actuator providing miller cycle benefits

An engine valve actuator, comprising:

• an actuator cylinder having a fluid passage;
• an actuator piston reciprocatingly disposed in the actuator cylinder;
• and
• a control valve operatively associated with the actuator cylinder, said control valve having a housing, said housing having a low pressure fluid inlet, a high pressure fluid inlet, and a fluid outlet, a plunger having first and second ends reciprocatingly disposed in the housing, the plunger being movable between a first position at which the low pressure fluid inlet is in communication with the fluid outlet, and a second position at which the high pressure fluid inlet is in communication with the fluid outlet, the fluid outlet being in fluid communication with the actuator cylinder fluid passage.

An engine, comprising:

• an engine cylinder;
• an engine piston reciprocatingly disposed in the engine cylinder;
• a valve reciprocatingly disposed in a port extending from the engine cylinder;
• a first source of pressurized fluid;
• a second source of pressurized fluid, the second source being pressurized to a higher level than the first source;
• and
• a valve actuator adapted to be in fluid communication with the first and second source of pressurized fluid, the first source taking up any lash associated with the engine, the second source causing the valve actuator to open the valve.

A method of controlling an engine, comprising:

• providing an engine having an engine cylinder, an engine piston reciprocatingly disposed in the engine cylinder, a valve port in fluid communication with the engine cylinder, a valve reciprocatingly disposed in the valve port, a fluidically driven valve actuator operatively associated with the valve, a mechanically driven valve actuator operatively associated with the valve, a source of low pressure fluid, and a source of high pressure fluid, the engine having intake, compression, power and exhaust strokes;
• supplying one of the low and high pressure fluid sources to the fluidically driven actuator;
• opening the valve during one of the intake and exhaust strokes using the mechanically driven actuator;
• and
• opening the valve during the compression stroke using the fluidically driven actuator.