Constant vacuum type carburetor

Claim 1

A CHARGE FORMING DEVICE FOR INTERNAL COMBUSTION ENGINES COMPRISING, IN COMBINATION: A BODY HAVING AN INDUCTION PASSAGE PROVIDING AN AIR INTAKE AND A MIXTURE OUTLET CONNECTABLE TO ENGINE MANIFOLDING; AN AIR VALVE, INCLUDING A VARIABLE CHOKE PISTON AND A NEEDLE VALVE, SLIDABLY POSITIONED ON THE BODY IN THE INDUCTION PASSAGE FOR CONTROLLING A SUPPLY OF FUEL AND AIR TO THE ENGINE; A FUEL METERING ORIFICE DISPOSED IN SAID INDUCTION PASSAGE OPPOSITE SAID NEEDLE VALVE TO COOPERATE THEREWITH; A THROTTLE VALVE ROTATABLY SUPPORTED IN THE INDUCTION PASSAGE ANTERIOR OF THE AIR VALVE FOR CONTROLLING THE INTRODUCTION OF A FUEL-AIR MIXTURE TO THE ENGINE A FLEXIBLE DIAPHRAGM MEMBER SEPARATING SAID BODY INTO A FIRST CHAMBER AND A SECOND CHAMBER, MEANS MAINTAINING SAID FIRS CHAMBER AT A REFERENCE PRESSURE, MEANS MAINTAINING SAID SECOND CHAMBER DURING ENGINE OPERATION AT A PRESSURE SUBSTANTIALLY EQUAL TO THAT IN THE PASSAGE INTERMEDIATE OF THE NEEDLE VALVE AND THE THROTTLE VALVE; A HOLLOW CLOSED HOUSING; FIRST CONDUIT MEANS INTERCONNECTING THE HOUSING AND THE SECOND CHAMBER; SECOND CONDUIT MEANS INTERCONNECTING THE HOUSING TO REFERENCE PRESSURE; A BLEED PISTON SLIDABLY DISPOSED FOR RECIPROCAL MOVEMENT WITHIN THE HOUSING, SAID BLEED PISTON HAVING A FIRST AND SECOND POSITION; A CHANNEL DISPOSED IN THE BLEED PISTON TO INTERCONNECT THE FIRST AND SECOND CONDUIT MEANS WHEN THE BLEED PISTON IS IN ITS FIRST POSITION; THIRD CONDUIT MEANS COMMUNICATING PRESSURE DOWNSTREAM OF THE THROTTLE VALVE TO THE HOUSING FOR MOVING THE BLEED PISTON TO ITS SECOND POSITION; RESILIENTLY YIELDABLY MEANS COOPERATING WITH THE CYLINDRICAL HOUSING AND THE BLEED FOR BIASING THE BLEED PISTON TO ITS POSITION WHEN THE ENGINE MANIFOLD VACUUM REACHES A PREDETERMINED VALUE.