Electromagnetic unit fuel injector

摘要

An electromagnetic unit fuel injector for use in a diesel engine includes a housing with a pump therein defined by a cam actuated plunger reciprocable in a bushing for supplying fuel via a discharge passage in the housing to a spring biased, pressure actuated, injection valve positioned to control flow discharge out through the spray tip outlet at one end of the housing. The discharge passage is also connected to a low pressure, fuel drain passage with flow from the discharge passage, which has a metering orifice passage at one end thereof, to the drain passage being controlled by a normally open, electromagnetic valve. During a pump stroke of the plunger, the electromagnetic valve is energized to thereby block flow from the discharge passage through the metering orifice passage to the low pressure fuel drain passage whereby to allow the pressure of fuel in the discharge passage to increase during the pump stroke of the plunger whereby to effect unseating of the injection valve.