Patent ID: 7281523

Claim:
A pump system for a fuel injection system in a diesel engine, the pump system having: a pumping chamber; a plunger disposed in the pumping chamber for pressurizing fuel; a fuel injector having an upper nozzle chamber, a lower nozzle chamber and a needle valve biased to a closed position by a spring wherein higher pressure in the lower nozzle chamber than in the upper nozzle chamber opens the needle valve and the spring closes the needle valve when pressure in the lower nozzle chamber is not higher than in the upper nozzle chamber; a fluid line connecting the pumping chamber to the lower nozzle chamber; and no more than one control valve fluidly connected between the pumping chamber or the fluid line and the upper nozzle chamber, wherein the upper nozzle chamber is fluidly connected to a reservoir with a restriction between the upper nozzle chamber and the reservoir, whereby a high pressure post injection event can occur without the need for a second control valve.