Proportional control valve assembly for exhaust gas recirculation system

A method of controlling flow rates of a first fluid utilizing fluid pressure supplied by a second fluid comprising the steps of:

• converting an electrical signal into a force imparted to a directional valve that controls a flow of the second fluid to a double-acting actuator;
• moving the directional valve in response to the force converted from the electrical signal between a first position that directs a flow of the second fluid to a first surface of the double-acting actuator and a second position that directs a flow of the second fluid to a second surface of the double-acting actuator;
• providing feedback between the double-acting actuator and the directional valve that overcomes the force imparted to the directional valve and restores the directional valve to a neutral position at which differential flows of the second fluid to the first and second surfaces are blocked;
• moving the double-acting actuator through a range of positions corresponding to different amounts of the feedback between the double-acting actuator and the directional valve at the neutral position of the directional valve;
• and
• linking movement of the double-acting actuator to movement of a flow-regulating valve that controls flow rates of the first fluid for changing flow rates of the first fluid through the flow-regulating valve in response to changes in the electrical signal.

A proportional control valve for regulating movement of a device comprising:

• a double-acting actuator movable under the influence of fluid power;
• the double-acting actuator being connected to the device for imparting corresponding movements to the device;
• the double-acting actuator having
• (a) a first surface arranged for exposure to fluid pressure for imparting movement to the double-acting actuator in a first direction and
• (b) a second surface arranged for exposure to fluid pressure for imparting movement to the double-acting actuator in a second direction;
• a directional valve that regulates flows of fluid to and from the first and second surfaces of the double-acting actuator;
• an electrical actuator that converts a control signal into a force acting on the directional valve;
• the directional valve being movable under influence of the electrical actuator between
• (a) a first position that directs flows of fluid to the first surface of the double-acting actuator and away from the second surface of the double-acting actuator for moving the double-acting actuator in the first direction,
• (b) a second position that directs flows of fluid to the second surface of the double-acting actuator and from the first surface of the double-acting actuator for moving the double-acting actuator in the second direction, and
• (c) a neutral position that blocks differential flows of fluid to and from the first and second surfaces of the double-acting actuator for preventing further movement of the double-acting actuator in the first and second directions;
• a feedback mechanism connecting the double-acting actuator to the directional valve for imparting a feedback force in response to movement of the double-acting actuator that restores the directional valve to a neutral position;
• a spacing between the double-acting actuator and the directional valve being related to the feedback force;
• and
• the feedback force being related to the force converted from the electrical signal for regulating movement of the device in accordance with the control signal.