Fuel feed control device for internal combustion engine

Claim 1

A fuel feed control device for an internal combustion engine comprising: a normally closed fuel injection valve for controlling the fuel quantity to be fed to the engine according to the opening duration thereof: spring means provided on said valve for applying a biasing force to said valve to urge said valve toward its closed position; valve control means for electromagnetically controlling the opening and closing operation of said valve; and said valve control means including electromagnetic coil means, a first means including a first circuit for enabling a first current to flow through said coil means for producing a first electromagnetic attraction force, a second means including a second circuit for enabling a second current to flow through said coil means for producing a second electromagnetic attraction force, and a third means including a third circuit for enabling a third current to flow through said coil means for producing backward magnetic flux, said first electromagnetic attraction force being insufficient to open said valve from its closed state against said biasing force but large enough to hold said valve in its open state against said biasing force after said valve has been once opened, said second electromagnetic attraction force being such that the sum of said first and second electromagnetic attraction forces is large enough to open said valve from its closed state, said backward magnetic flux being for cancelling magnetic flux which is induced when said first electromagnetic attraction force is obviated to close said valve from its open state and which acts to prevent said first electromagnetic attraction force from disappearing, said first means being actuated to produce said first electromagnetic attraction force at least for a period across the pulse width of an incoming external demand pulse which instructs the fuel quantity to be fed by said valve, said second means being actuated to produce said second electromagnetic attraction force in addition to said first electromagnetic attraction force at least for a period from the beginning of the pulse width of said demand pulse to the completion of the valve opening operation, said third means being actuated to produce said backward magnetic flux upon the end of the pulse width of said demand pulse, said first circuit comprising a first series circuit including said coil means, a resistor and a first switching means; said second circuit comprising a second series circuit including said coil means, a capacitor, and a second switching means; and said third circuit comprising a third series circuit including said coil means and a third switching means, said first, second and third switching means being actuated in response to said demand pulse.