Self-priming carburetor

Claim 1

In combination, an internal combustion engine operable to run in a given speed range and in an ambient temperature environment of about 40* to 120* F., a predetermined external load connected to said engine, a chokeless carburetor for automatically supplying a priming charge of fuel and air to said engine under open throttle conditions and in a given engine cranking speed range without the use of a choke, strangling or supplemental pressurizing fuel lifting means, said carburetor comprising an air-fuel mixture conduit having an air inlet and a fuel-air outlet connected to the fuel-air intake of said engine, said carburetor having a float bowl type fuel supply, an oversize priming charge fuel well and a main fuel passage serially connecting said supply to said conduit for induction of fuel from said supply to said conduit between said inlet and outlet thereof solely due to the subatmospheric pressure created by the airstream drawn through said conduit directly from the inlet to the outlet thereof by the intake vacuum generated by said engine, a throttle valve in said conduit constituting the sole variable air restrictor in said conduit, said throttle having a wide open starting position presenting a minimum restriction to air flow through said conduit, an air bleed passage having an inlet opening to a source of air at a pressure greater than that at said main fuel passage outlet and having an outlet opening to said priMing well, and a metering orifice connecting said fuel well to said fuel supply and operable to fill said fuel well to a given full level with a predetermined priming charge of liquid fuel from said supply only when said engine is stationary and to control the rate of liquid fuel supply to said well when the engine is running, said main fuel passage having an inlet in said well below said given level and an outlet opening to said conduit constantly exposed to the air flowing directly from the inlet to the outlet of said conduit past said passage outlet while said engine is being cranked at starting speed with said throttle at said open position, said conduit, passage and well being sized and oriented relative to one another and the engine such that when full said priming well and said passage between said inlet thereof and said given level has a volumetric capacity correlated with the air flow and aspirating characteristics of said conduit when said engine is cranked for starting with said throttle open to said starting position such that said well is substantially evacuated of the liquid fuel between said passage inlet and said given level during the induction of said priming charge from said well to said conduit via said passage by said subatmospheric pressure developed in said conduit in response to the engine being cranked from one to several revolutions at a start-up cranking speed in said given engine cranking speed range to thereby supply said priming charge to the engine as the sole source of fuel to enable starting of the engine while said throttle is maintained at said open position.