Unit injector for gasoline engines

A unit injection comprising:

• a housing including upper and lower hollow sections;
• a coil assembly received within the upper section comprising a coil, a passage and a seal between the coil and upper housing section;
• a stator received within the passage, comprising a wall defining a first blind bore open at a top end and closed at a bottom end with a narrow first flow passage formed in said bottom end, the bottom end recessed upwardly from the lower end of the wall and defining a first valve seat downstream of the first flow passage;
• a piston loosely received with the first blind bore of the stator sufficient to permit fuel through a second flow passage therebetween, the lower portion of the piston and the first blind bore cooperating to form a pressure chamber, including a lip seal operative to seal the second flow passage and pressure chamber when the piston is urged downardly and to open the second flow passage and pressure chamber when the piston is urged upwardly;
• means for defining a flexible, resilent fuel receiving chamber in fluid communication with the second flow passage positioned about the upper portion of the housing for reciprocating the piston within the second flow passage comprising an outer electrically conductive flexible first bellows including a top portion secured to the piston and a flexible, springlike wall surrounding the top portion of the housing, a lower insulative section secured to the housing and sealingly engaging an end of the wall of the first bellows;
• means for establishing electrical connections with the coil including an electrically insulative washer positioned upon the stator, an electrically conductive member, and a conductive return spring extending from the conductive member in electrical contract with the first bellows, the return spring connected to a wire of the coil;
• another wire of the coil being connected to the housing, and means for applying electrical energy to the first bellows including a signal wire;
• an armature assembly, including an armature slidably positioned within the housing responsive to a force generated upon excitation of the coil, including a second blind bore for receiving fuel from the narrow passage, a pin extending from the armature into the hollow lower section of the housing, the pin including a sealing surface, the armature including a plurality of flow passages for communicating fuel from the second blind bore to the lower housing section;
• and a bias spring for urging the armature and pin outwardly;
• a valve seat assembly forming in cooperation with the housing a lower fuel chamber comprising a valve seat secured within an exit end of the hollow lower housing portion and adapted to receive the pin for controlling the flow of fuel through a metering orifice, formed in the valve seat, a pin guide position upon the valve seat, for guiding the pin onto the valve seat, including a contoured surface which forms in cooperation with the valve seat a swirl chamber a plurality of flow passages for communicating fuel from the lower chamber to the swirl chamber and a spring member having an opening for communicating fuel from the lower chamber to the plurality of passages in the pin guide;
• a check valve, responsive to a pressure differential thereacross, is secured to the stator and is operative to control the flow of fuel through the narrow passage in response to the pressure differential;
• a first accumulator means, including a closed bellows disposed within the bore second blind of the armature for pressurizing the fuel upstream of the metering orifice and for controlling the rate at which fuel is ejected upon excitation of the coil.