Spool type control valve for controlling hydraulic actuators

Claim 1

A HYDRAULIC CONTROL VALVE COMPRISING A HOUSING, SAID HOUSING HAVING A BORE THERETHROUGH, AN INLET PORT, AN OUTLET PORT, A PLURALITY OF AXIALLY SPACED APART ANNULAR CHAMBERS COMMUNICATING WITH SAID BORE, A PASSAGEWAY LEADING BETWEEN AT LEAST ONE SUCH CHAMBER AND THE OUTLET OF SAID VALVE, A PASSAGEWAY COMMUNICATING BETWEEN AT LEAST ONE SUCH CHAMBER AND THE INLET OF SAID VALVE AND A VALVE ELEMENT SLIDABLY MOUNTED IN SAID BORE, SAID VALVE ELEMENT HAVING AT LEAST ON RECESS THEREIN, THE IMPROVEMENT COMPRISING A PAIR OF SPACED APART ANNULAR CHAMBERS CONCENTRIC WITH SAID BORE, SAID PAIR OF ANNULAR CHAMBERS BEING INCLINED WITH RESPECT TO THE AXIS OF SAID BORE, THE PORTION OF SAID HOUSING BETWEEN SAID PAIR OF CHAMBERS COMPRISING A FLOW CONTROL PORT, SAID FLOW CONTROL PORT INCLUDING A FIRST AND SECOND SIDE EDGE, SAID SIDE EDGES ALSO BEING INCLINED WITH RESPECT TO THE AXIS OF SAID BORE, ONE CHAMBER OF SAID PAIR COMMUNICATING WITH THE INLET OF SAID VALVE AND THE OTHER CHAMBER OF SAID PAIR COMMUNICATING WITH THE OUTLET OF SAID VALVE, SAID VALVE ELEMENT INCLUDING A RECESS, SAID RECESS HAVING SIDE EDGES POSITIONED SUBSTANTIALLY PERPENDICULAR TO THE AXIS OF SAID MOVABLE VALVE ELEMENT, SAID SIDE EDGES BEING ADAPTED TO COOPERATE WITH SAID FLOW CONTROL PORT WHEREBY AXIAL MOVEMENT OF SAID VALVE ELEMENT AT A CONSTANT RATE WITH RESPECT TO SAID HOUSING GRADUALLY CLOSES OR OPENS SAID FLOW CONTROL PORT THEREBY CONTROLLING THE FLOW OF HYDRAULIC FLUID THROUGH SAID VALVE.