Abstract: Check valves (500) are incorporated into a fuel injector so as to form a controlling orifice in the system between the solenoid vales which direct fuel to the respective injection and timing chambers of the fuel injector and the chambers themselves. The precision fuel metering capability of the valve (500) is determined by an annular clearance created between the plunger (512) of the valve and the valve body (510) when the valve is in its maximum stroke. For achieving a bi-stable operation of the valve, the ratio of the plunger valve seat (510d) area to the maximum plunger valve (512b) area and the spring (514) are key parameters. The check valves (500) are formed as cartridge type check valves that can be calibrated outside of the injector prior to the installation thereof.

Abstract: A fuel injector for effectively preventing excessive loading of a component mounted internal to the injector is provided which includes a one-piece retainer having first and second connector portions for permitting two independent loads to be applied to different internal components of the injector. The second connector portion includes threads for engaging a nozzle assembly to impart a compressive force on the nozzle assembly. The first connector portion also includes threads for engaging an outer barrel for placing a first compressive load on a load sensitive internal component, such as a center tube of an injection control valve. In this manner, the second compressive force can be set at a minimum level independent from the first compressive force to permit the size of the center tube to be minimized thereby reducing the overall size of the injector.

Abstract: An electromagnetic fuel injection control valve positioned inside a fuel injector, i.e. a unit injector, for providing fast response and high pressure capability while minimizing the size and complexity of the injector. The control valve includes a valve housing having a supply inlet and fuel outlet, a center tube having a center passage and an annular valve seat, a control valve sleeve slidably mounted on the center tube and an actuator assembly having a coil spring, a stator and an armature. The control valve sleeve moves between an open position permitting fuel to flow between the supply inlet and the fuel outlet and a closed position which sealingly engages the annular valve seat for blocking the flow of fuel between the supply inlet and the fuel outlet. The coil spring biases the control valve sleeve in an open position and is positioned around the center tube. The stator is also axially positioned around the center tube and includes multiple poles.