Warning and/or control device for use with aircraft fuel supply systems

Claim 1

IN AN AIRCRAFT FUEL SUPPLY SYSTEM INCLUDING A MAIN FUEL PUMP HAVING AN INLET AND AN OUTLET, A HOLLOW BODY, A PRESSURE SENSITIVE MEMBER WITHIN THE BODY AND SERVING IN PART TO DEFINE A COMPARTMENT WITHIN SAID BODY, PASSAGE MEANS CONNECTING SAID COMPARTMENT TO THE INLET TO THE MAIN FUEL PUMP, A BY-PASS CIRCUIT INTERCONNECTING THE INLET AND OUTLET OF THE MAIN FUEL PUMP, A CHAMBER FORMING PART OF SAID BY-PASS CIRCUIT, RESTRICTION MEANS IN SAID CHAMBER FOR VAPORISING A PORTION OF THE FUEL FLOWING THROUGH THE BY-PASS CIRCUIT, SO THAT THE PRESSURE IN SAID CHAMBER IS THE VAPOR PRESSURE OF THE FUEL, MEANS FOR SUBJECTING THE PRESSURE SENSITIVE MEMBER TO SAID VAPOR PRESSURE SO THAT THE VAPOR PRESSURE ACTS TO URGE SAID PRESSURE SENSITIVE MEMBER IN A DIRECTION OPPOSITE TO THE DIRECTION IN WHICH IT IS URGED BY THE PRESSURE OF FUEL IN THE FUEL SYSTEM ENTERING THE MAIN FUEL PUMP, MEANS FOR SUBJECTING THE PRESSURE SENSITIVE MEMBER TO FURTHER FORCES TO BALANCE THE FORCES ACTING ON THE PRESSURE SYSTEM UNDER NORMAL OPERATING CONDITIONS, A SWITCH, AND A SWITCH ACTUATING MEMBER MOVABLE BY SAID PRESSURE SENSITIVE MEMBER TO ACTUATE THE SWITCH WHEN THE PRESSURE OF FUEL ENTERING THE MAIN FUEL PUMP FALLS BELOW A PREDETERMINED VALUE WHICH VARIES WITH SAID VAPOR PRESSURE.