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A unit fuel injector for a fuel injection system for an internal combustion engine is described that is reciprocably driven from a camshaft by a drive train, and the unit injector includes a device for controlling the rate of fuel injection into an engine cylinder. The rate control device operates t

A unit fuel injector for a fuel injection system for an internal combustion engine is described that is reciprocably driven from a camshaft by a drive train, and the unit injector includes a device for controlling the rate of fuel injection into an engine cylinder. The rate control device operates to divert or bleed off a quantity of fuel from the main metering chamber of an open-nozzle type fuel injector during an initial phase of injection, and the diverted fuel is returned to the metering chamber at a later phase in the injector operation. The rate control device includes an auxiliary metering chamber which receives the diverted fuel via an auxiliary passageway. An auxiliary plunger is mounted within the auxiliary metering chamber. A biasing device such as a helical spring or a fluid pressure spring, controls the inward and outward movement of the auxiliary plunger. The biasing device causes the auxiliary plunger to return the diverted fuel to the metering chamber when the pressure of the auxiliary plunger biasing device exceeds the fluid pressure within the metering chamber. In one embodiment, the biasing device is adjustable by controlling a control pressure of a fluid pressure spring.

대표청구항 ▼

A cyclically operating unit fuel injector for controlling the rate of fuel injection in a fuel injection system of an internal combustion engine having a cam shaft for synchronously operating the unit injector, said fuel injector comprising: an injector housing having an axial bore with an injection

A cyclically operating unit fuel injector for controlling the rate of fuel injection in a fuel injection system of an internal combustion engine having a cam shaft for synchronously operating the unit injector, said fuel injector comprising: an injector housing having an axial bore with an injection orifice at one end; a plunger mounted for reciprocating movement within said axial bore of said housing and translatable between a retracted position and an advanced position in response to rotation of the camshaft to inject during each cycle of variable quantity of fuel up to a maximum quantity through said injection orifice into a combustion chamber of the engine; plunger biasing means for biasing said plunger toward said retracted position; and rate control means for reducing the rate of fuel injection during a first phase of the injector cycle by bleeding off a portion of the fuel to be injected from said axial bore during said first phase of the injector cycle and by returning the fuel to said axial plunger bore during a subsequent phase of the injector cycle, said rate control means comprising an auxiliary metering chamber which receives the fuel bled from said axial bore and an auxiliary passageway disposed in fluid communication between said axial bore and said auxially metering chamber to transmit fuel to and from said axial bore and said auxiliary metering chamber, said auxiliary passageway being reduced sufficiently in size to restrict the flow of fuel therethrough during the injector cycle to a desired level in order to control the bleeding off of fuel in said fist phase and the return of fuel to the axial plunger bore during said subsequent phase.