Fuel injection apparatus and system

In combination, a combustion engine, fuel metering apparatus for supplying metered rates of fuel flow to said engine, said fuel metering apparatus comprising body means, induction passage means formed through said body means for supplying motive fluid to said engine, throttle valve means situated in said induction passage means for variably controlling the rate of flow of air through said induction passage means, fuel-air mixture discharge means situated in said induction passage means downstream of said throttle valve means, air passage means communicating between a source of air and said fuel-air mixture discharge means, said air passage means comprising flow restriction means, said flow restriction means being calibrated as to provide for sonic flow therethrough at conditions of idle engine operation, fuel metering means for metering liquid fuel in response to engine demands and indicia of engine operation, said liquid fuel when metered by said fuel metering means being discharged into said air passage means at an area thereof downstream of said source of air and upstream of said flow restriction means, said flow restriction means comprising sonic venturi type restriction means, said fuel metering means for metering liquid fuel comprising a duty-cycle type fuel metering solenoid assembly, said fuel metering solenoid assembly comprising bobbin means, a ball armature means, a field winding carried by said bobbin means, said bobbin means and said field winding being selectively adjustably positionable with respect to said ball armature means, said field winding being intermittently energizable during metering of said liquid fuel as to cause said ball armature means to move toward and away from a closed position with respect to an associated valve seat member and thereby result in an average rate of flow of fuel past said ball armature means which consitutes the then metered rate of liquid fuel flow, pole piece means extending through said bobbin means, said pole piece means having a pole face of a configuration complimentary to said ball armature means, and relieved portions formed in said pole face to permit flow of fuel therethrough, unmetered fuel passage means for supplying unmetered fuel to said fuel metering means upstream of said fuel metering means, pressure regulator means operatively communicating with said unmetered fuel for regulating the pressure thereof to a preselected superatmospheric magnitude, said fuel-air mixture discharge means comprising generally annular means defining generally annular passage means, said air-passage means in communicating with said fuel-air mixture discharge means communicates with said generally annular passage means, and discharge port means communicating between said generally annular passage means and said induction passage means for directing the flow of the fuel-air mixture within said generally annular passage means to said induction passage means, said discharge port means comprising a plurality of discharge ports spaced from each other and directed generally radially inwardly of said induction passage means.