Patent ID: 7100573

Claim:
A fuel injection system comprising a nozzle ( 2 ) with an inlet and a needle ( 15 ); a resilient means ( 14 ) biasing the needle ( 15 ) to close the nozzle ( 2 ); a control piston ( 16 ) forming a control chamber ( 17 ) and abutting the needle ( 15 ) such that a higher pressure in the control chamber ( 17 ) tends to urge the control piston ( 16 ) onto the needle ( 15 ) to close the nozzle ( 2 ); a cam-driven plunger ( 5 ) forming a plunger chamber ( 7 ), said plunger chamber connected to the inlet of the nozzle ( 2 ); a common rail ( 11 ) for fuel; a feed line ( 13 ); an electrically operated valve ( 9 ) being able to isolate said plunger chamber ( 7 ) from the common rail ( 11 ) and connect the plunger chamber ( 7 ) to the feed line ( 13 ) while in a third position, isolate the plunger chamber ( 7 ) from both the feed line ( 13 ) and the common rail ( 11 ) while in a second position, and isolate the plunger chamber ( 7 ) from the feed line ( 13 ) and connect the plunger chamber ( 7 ) to the common rail ( 11 ) while in a first position; a means ( 12 ) for pressurizing a feed line ( 13 ) with a relatively low fuel feed pressure; and a fuel tank ( 20 ), said fuel injection system characterized in that said control chamber ( 17 ) is connected to the common rail ( 11 ).