Fuel system with metering pump for internal combustion engines

Claim 1

A fuel supply system for supplying volatile fuel at a controlled rate to an air-fuel mixing chamber leading to a subatmospheric intake manifold of an internal combustion engine, said system comprising: a positive displacement rotary metering pump having an inlet side and a discharge side for pumping fuel from said inlet side to said discharge side, fuel pump means for supplying volatile fuel from a fuel reservoir to said inlet side at a substantial elevated pressure at which said fuel remains liquid passing through said metering pump, equalizer valve means including a valve body forming a valve chamber with an outlet opening therefrom, a resilient diaphragm dividing said valve chamber into first and second parts with said outlet opening in said first part and mounted in said valve body for movement by pressure differentials between said first and second parts, a valve closure member for closing said outlet opening supported in said valve chamber by said diaphragm for motion therewith, and means biasing said diaphragm to effect closure of said outlet opening by said valve closure member when the pressure in said first part is less than a small differential greater than the pressure in said second part, said small predetermined differential being insufficient to produce any substantial leakage of liquid through said metering pump, first fluid conduit means connecting said discharge side of said metering pump to said first part of said valve chamber, second fluid conduit means connecting said inlet side of said metering pump to said second part of said valve chamber, third fluid conduit means for connecting said outlet opening from said valve chamber to said air-fuel mixing chamber, a variable speed electrical pump motor coupled to said metering pump for driving said metering pump, control means for providing an electrical control signal systematically related to a desired rate of fuel supply, speed measuring means coupled to said metering pump for producing a feedback signal systematically related to metering pump speed, and circuit means responsive to said control signal and said feedback signal for providing electrical power to said pump motor to drive said motor at a controlled rate whereat said positive displacement metering pump pumps said volatile fuel at substantially the desired rate from said inlet side to said discharge side, whence said fuel flows at substantially said desired rate through said first conduit means to said first part of said valve chamber wherein it produces pressure relative to that in said second part whereat said valve closure member is positioned relative to said outlet opening for said fuel to flow therethrough at said desired rate to said air-fuel mixing chamber.