HIGH PRESSURE FUEL INJECTOR WITH FUEL DRAINAGE VALVE

摘要

An improved high pressure fuel injector (10') for internal combustion engines in which problems of hysteresis delays and fuel leakage at the commencement of the metering process can be avoided without affecting the ability to precisely control the fuel supply pressure by the provision of a way for the metering and injection plunger (26) to be acted upon only by the pressure of the incoming fuel supply. An improved metering and injection plunger spring arrangement (68, Sd) provides a valving of the drain path (44) that prevents leakage through drain passages (44, 66) and/or about the metering and injection plunger (26) during the fuel metering and injection phases. Also, a double check valve arrangement (34, 38) is incorporated into the plunger seat disc (6) to minimize the possibility of back-flow leakage of fuel during injection of the fuel from the metering and injection chamber (M).