Flow control valve

Claim 1

A FLOW CONTROL VALVE COMPRISING: A HOUSING HAVING AN INLET PORT AND AN OUTLET PORT; A PISTON POSITIONABLE TO CONTROL THE RATE OF FLOW OF FLUID PASSING THROUGH SAID OUTLET PORT; A SOURCE OF HIGH PRESSURE FLUID; A FLOW TRANSDUCER FOR ESTABLISHING A FIRST ELECTRICAL SIGNAL INDICATIVE OF THE RATE OF FLOW OF FLUID PASSING THROUGH SAID INLET PORT, SAID TRANSDUCER INCLUDING AN ELECTRIC COIL, AN ARMATURE MOVABLE WITH RESPECT TO SAID COIL IN RESPONSE TO VARIATION OF THE RATE OF FLOW OF FLUID THROUGH SAID HOUSING, AND MEANS ACTUABLE IN RESPONSE TO MOVEMENT OF SAID PISTON BY SAID HIGH PRESSURE FLUID TO CAUSE MOVEMENT OF SAID ARMATURE WITH RESPECT TO SAID COIL; MEANS ESTABLISHING A SECOND ELECTRICAL SIGNAL INDICATIVE OF A DESIRED RATE OF FLOW OF FLUID THROUGH SAID HOUSING; MEANS FOR COMPARING SAID FIRST AND SECOND ELECTRICAL SIGNALS AND ESTABLISHING A DIFFERENCE SIGNAL; SIGNAL RESPONSIVE MEANS RESPONSIVE TO SAID DIFFERENCE SIGNAL FOR SUPPLYING FLUID FLOWING THROUGH SAID HOUSING TO SAID PISTON TO POSITION SAID PISTON TO MAINTAIN SAID DESIRED RATE OF FLOW OF FLUID THROUGH SAID HOUSING; AND MEANS FOR CAUSING SAID SIGNAL RESPONSIVE MEANS TO PERMIT PASSAGE OF HIGH PRESSURE FLUID FROM SAID SOURCE TO SAID PISTON TO ACTUATE SAID PISTON IN THE ABSENCE OF FLUID FLOW THROUGH SAID HOUSING.