Fuel controlling device for injection type internal combustion engines

Claim 1

A fuel control device for a fuel injection type internal combustion engine comprising electrical control means comprising means for producing a d.c. voltage proportional to the rotational speed of the engine, said means comprising means for producing electrical pulses in accordance with the rotational speed of the engine, means comprising a capacitor charging circuit for converting said pulses into a d.c. voltage and a simple transistor amplifier for amplifying said d.c. voltage, the output of said charging circuit constituting the sole input to said transistor amplifier; potentiometer means connected in series with the collector of said transistor amplifier, for varying the position of the tap of said potentiometer in accordance with the position of an accelerator operator to produce a corresponding output voltage at said tap, a first Schmitt trigger circuit having a first operating voltage, a second Schmitt trigger circuit having a second, different operating voltage, means for connecting said potentiometer tap to the inputs of said first and second Schmitt trigger circuits, a first, fuel supply-increasing electromagnetic relay responsive to said first Schmitt trigger circuit, and a second, fuel supply-decreasing electromagnetic relay responsive to said second Schmitt trigger circuit, phase inverter means connected between one of said Schmitt trigger circuits and the corresponding electromagnetic relay, and hydraulic servo-motor means comprising a differential pressure chamber including first and second subchambers, a first, fuel supply-increasing electromagnetic valve responsive to said first relay for controlling the inflow and outflow of a pressure fluid to said first sub-chamber and actuated when said output voltage is below the lower of the operating voltages of said Schmitt trigger circuits, a second, fuel supply-decreasing electromagnetic valve responsive to said second relay for controlling the inflow and outflow of a pressure fluid to said second sub-chamber and actuated when said output voltage exceeds the higher of the operating voltages of said Schmitt trigger circuits, pressure regulating valve means for regulating the pressure within said sub-chambers,, and means responsive to the pressure differential chamber for controlling movement of a fuel regulating rod, the last named means causing displacement of said fuel regulating rod in a direction to increase the fuel supply when said fuel supply-increasing valve is actuated, causing displacement of said fuel regulating rod in a direction to decrease the fuel supply when said fuel supply-decreasing valve is actuated, and not causing displacement of said fuel regulating rod when said output voltage is between said lower and higher voltages.