Electrohydraulic flow control apparatus

Claim 1

FLOW CONTROL APPARATUS COMPRISING THE COMBINATION OF, (A) ORIFICE MEANS, SAID MEANS COMPRISING A BODY HAVING AN INLET, AN OUTLET THE AREA OF WHICH CAN BE BETWEEN SAID INLET AND OUTLET THE AREA OF WHICH CAN BE VARIED, SAID STRUCTURE INCLUDING A MOVABLE MEMBER, A SEPARATE PRESSURE CHAMBER ASSOCIATED WITH EACH OF TWO OPPOSITELY FACING EQUAL AREAS OF SAID MOVABLE MEMBER, SAID MEMBER BEING MOVABLE IN RESPONSE TO UNEQUAL PRESSURES ON SAID AREAS IN SAID CHAMBERS TO VARY THE AREA OF SAID ORIFICE; (B) PRESSURE REGULATOR MEANS FOR MAINTAINING A CONSTANT DIFFERENTIAL BETWEEN THE PRESSURES OF FLUID AT THE INLET AND AT THE OUTLET OF SAID ORIFICE MEANS, WHEREBY FOR A GIVEN AREA OF SAID ORIFICE THE FLOW OF FLUID THROUGH SAID ORIFICE TO SAID OUTLET IS MAINTAINED CONSTANT; (C) A PILOT VALVE INCLUDING AN INLET, AN OUTLET, AND A MOVABLE VALVE MEMBER COOPERABLE WITH A PORT AND AN ELECTRIC TRANSDUCER FOR ACTUATING SAID VALVE MEMBER IN ACCORDANCE WITH AN ELECTRIC SIGNAL APPLIED THERETO; AND (D) PASSAGE MEANS INCLUDING A FLOW RESTRICTOR INTERCONNECTING THE INLET OF SAID PILOT VALVE WITH THE INLET OF SAID ORIFICE MEANS, PASSAGE MEANS INTERCONNECTING THE INLET OF SAID PILOT VALVE WITH ONE OF SAID CHAMBERS, AND PASSAGE MEANS INTERCONNECTING THE OUTLET OF SAID PILOT VALVE WITH THE OUTLET OF SAID ORIFICE MEANS AND THE OTHER OF SAID CHAMBERS.