Fuel injection apparatus for internal combustion engines

A fuel injection apparatus for use in an internal combustion engine, which comprises:

• a piston housing;
• a servo piston having a large size portion having opposite end faces, and a small size portion having an end face remote from said large size portion, said large size portion defining a servo-pressure chamber and a counter-servo-pressure chamber between said opposite end faces thereof and associated inner surfaces of said piston housing, said small size portion defining a pump working chamber between said end face thereof remote from said large size portion and associated inner surfaces of said piston housing;
• said servo piston having an outer peripheral surface thereof formed with a notch, said notch opening in an end face of said servo piston facing said servo-pressure chamber and having a base thereof extending obliquely to the axis of said servo piston, said piston housing having a peripheral wall thereof formed with a spill port communicating with a zone under lower pressure, said spill port being located for engagement with said notch;
• injection nozzle means arranged in communication with said pump working chamber;
• means for feeding operating fluid under pressure to said servo-pressure chamber and to said counter-servo-pressure chamber;
• selector valve means connecting said servo-pressure chamber and said counter-servo-pressure chamber to said operating fluid pressure feed means and being changeable in valve position to allow operating fluid to be alternately supplied from said operating fluid pressure feed means to said servo-pressure chamber and to said counter-servo-pressure chamber;
• means for feeding fuel under pressure to said pump working chamber, said fuel pressure feed means being provided separately from and independently of said operating fluid pressure feed means;
• actuator means connected to said servo piston for rotating same;
• and
• means coupling said servo piston to said actuator means in a manner allowing free axial displacement of said servo piston but forcing rotation thereof in unison with said actuator means;
• whereby rotation of said servo piston to change a circumferential position thereof through said actuator means causes a change in the compression stroke of said servo piston to thereby achieve control of the injection quantity of fuel through said injection nozzle means, while achieving control of the timing of injection beginning of fuel through said injection nozzle means by changing the timing of change of the valve position of said selector valve means.