Fill metered hydraulically actuated fuel injection system and method of fuel injection

摘要

The fill metered hydraulically actuated fuel injection system of the present invention utilizes an actuation fluid, preferably lubricating oil, as its actuation medium that is separate and different from the fuel fluid which is actually injected into the engine. Injectors according to the present invention are hydraulically actuated and include a conventional VOP type needle check, and fuel is pressurized by a plunger driven by an intensifier piston. The end of each injection event is achieved when the plunger and piston reach the end of their strokes, which provides for an abrupt end to each injection event. An abrupt end to injection is further accomplished by providing a pressure relief passage in the plunger that relieves pressure acting on the needle check at the end of injection in order to both quickly dissipate residual fuel pressure and allow the needle check to close more rapidly. Fuel is metered into the injector either by biasing the plunger with a return spring or by pressurizing the fuel to hydraulically push the plunger in a retracting direction between injection events.