Needle controlled fuel system with cyclic pressure generation

摘要

The improved needle controlled common rail fuel system of the present invention includes split common rails serving respective sets of injectors and a respective high pressure pump associated with each rail. The high pressure pumps reciprocate to cyclically create gradual periods of increasing pressure in the common rail during the advancement stroke of the plunger followed by respective periods of decreasing pressure during the plunger's retraction stroke. The fuel injectors include an injection control valve and a needle control device for creating an injection event during a pumping event by controlling the fuel flow to drain so as to control the fuel pressure forces acting on an injector needle valve element. A flow limiting device is provided to limit the fuel flow from a control volume to drain during an injection event thus reducing parasitic losses while maintaining quick valve closing. The system also includes an improved fuel injector design including an intensification plunger assembly. In addition, a pressure energy recuperation means is provided which utilizes the pressure of the fuel in the common rail and the fuel injectors as a result of the pressure energy stored in the fuel to assist in retraction of the high pressure pump plunger during each pumping event. In addition, a wiring connection harness is provided which permits the connection of an electrically operated fuel delivery device, i.e. injector, to an electrical source simultaneously with the mounting of the fuel delivery device on the engine.