Fuel pump

Claim 1

A fuel pump for delivering liquid fuel to an engine comprising: a housing having low and high pressure operating passages, one of which is an inlet passage and the other an outlet passage; means forming a cam surface in said housing; a rotor rotatably mounted within said cam surface, said rotor having a plurality oF radial slots; means forming a first and second chamber between the outer periphery of said rotor and said cam surface; means respectively connecting said inlet and outlet passages to said first and said second chambers; first means reciprocably mounted in at least some of said slots and engaging said cam surface for displacing fluid through said first chamber to form a first pumping means; passageway connecting said first chamber to said second chamber; second means reciprocably mounted in at least some of said slots and engaging said cam surface for displacing fluid through said second chamber to form a second pumping means and whereby a single liquid flow path is defined from said inlet passage through said chambers of said first and second pumping means to said outlet passage; said first pumping means comprising an axial portion of said rotor greater than said second pumping means so that the pumping capacity of the first pumping means is greater than the pumping capacity of said second pumping means whereby fuel is de-livered from said first pumping means in an amount and at a pressure in excess of that required for pumping by said second pumping means; and means carried in said housing intermediate said first and second chambers and communicating with said passageway connecting said first and second chambers for regulating the pressure delivered to said second chamber to a predetermined constant pressure value to insure that the fuel delivered by the second pumping means will be substantially vapor free and for returning excess liquid from the outlet of said first pumping means to the inlet of said first pumping means.