Fuel injection pump with an injection timing control device

Claim 1

A distributor type fuel injection pump for use with a diesel engine for successively supplying pressurized fuel to engine injectors in synchronism with engine rotation, said fuel injection pump including an angularly movable control member adapted to determine the timing of fuel injection in accordance with its angular position, and an injection timing control device for varying the angular position of said control member, said injection timing control device comprising: (a) a casing (b) a piston drivingly connected to said control member and located for reciprocating movement within said casing to form first and second pressure chambers at the respective ends thereof, said first pressure chamber having a first release port and a first inlet port, said second pressure chamber having a second release port and a second inlet port, said piston formed therein with first and second pressure passages, said first pressure passage communicating a pressure source with said first inlet port, said second pressure passage communicating said pressure source with said second inlet port; (c) control circuit means for calculating an optimum injection timing value for an engine operating condition from various engine operating parameters and providing a control signal indicative of the calculated injection timing value; and (d) valve means responsive to the control signal from said control circuit means for varying the ratio of the effective area of said first pressure passage to that of said second pressure passage to create a pressure difference across said piston, whereby said piston moves to move said control member to an angular position corresponding to the calculated injection timing value.