High pressure electronic common-rail fuel injection system for diesel engines

Claim 1

An electromagnetic injector for supplying fuel to an internal combustion engine, comprising: an injector body having an upper portion and a lower portion, and having an internal passage means with a first end in said upper portion for passing pressurized fuel to the lower portion; a solenoid actuated shuttle plunger slideably mounted at the upper end of said passage means having a pressure balanced annulus operable between a solenoid de-energized position in which the high pressure fuel is blocked from passing to said passage means, and a solenoid energized position in which the high pressure fuel is delivered to said passage means; a needle valve movable in the body to control the flow of pressurized fuel through the second end of said passage means, said needle valve being movable in a first direction toward an open position for passing pressurized fuel through the lower end of said passage means when said solenoid actuated shuttle plunger is in said solenoid energized positions, and an opposite, second direction toward a closed position for blocking pressurized fuel from passing through the lower end of said passage means when said solenoid actuated shuttle plunger is in said solenoid de-energized position; a spring cage having an upper chamber and a lower chamber, and a first sized orifice therebetween; an adjustable second valve slidable mounted in said lower portion of said body and having means to communicate into said spring cage the remaining pressurized fuel in said passage means after said first solenoid actuated shuttle plunger moves into solenoid de-energized position and blocks the high pressurized fuel from passing to said passage means; said spring cage having the high pressurized fuel coming from the upper chamber to the lower chamber of said spring cage and acting on the top of said spring seat to further bias said needle valve to a closed position when said solenoid actuated shuttle plunger is in said solenoid de-energized position to thereby obtain a sharp end of injection; and a second sized orifice in said spring cage in fluid communication with means to maintain a residual fuel pressure within said spring cage when said solenoid actuated shuttle plunger is in said solenoid de-energized position to thereby slow the movement of said needle valve in said first direction toward an open position when said solenoid actuated shuttle plunger is next in said solenoid energized position.