Patent ID: 6029902
Filing Date: 2000-02-29
Classification: F02M

Abstract:
A unit fuel injector for injecting fuel into a combustion chamber of an internal combustion engine, comprising:an injector body containing a central bore and an injection orifice formed in one end to discharge fuel into the combustion chamber;a lower plunger positioned for reciprocal movement in said central bore;a metering chamber positioned between said lower plunger and said injection orifice for receiving a metered quantity of fuel for injection on a periodic basis;fluid timing means for varying the timing of each periodic injection of metered fuel dependent upon the pressure of a timing fluid supplied to said injector body, said fluid timing means including an upper plunger mounted for reciprocal movement within said central bore, an intermediate plunger mounted for reciprocal movement within said central bore between said upper and said lower plungers and a variable volume timing chamber formed in said central bore between said intermediate plunger and said upper plunger for receiving timing fluid to form a fluid link having a variable effective length;a spring chamber formed axially between said intermediate plunger and said metering chamber;a spring means positioned in said spring chamber for biasing at least one of said intermediate plunger and said lower plunger toward said upper plunger; anda spring chamber drain valve means for directing fuel and timing fluid from said spring chamber to a low pressure drain and for preventing flow from said low pressure drain into said spring chamber.