Electromagnetic unit fuel injector

Abstract

An electromagnetic unit fuel injector for use in a diesel engine includes a housing having a bushing with an externally actuated plunger reciprocable therein to define a pump chamber open at one end for the discharge of fuel to a spring biased, pressure actuated fuel injection nozzle. The pump chamber is connected to a supply and spill chamber means via flow-through solenoid actuated, normally open, hollow pressure sensitive valve to permit the ingress and egress of fuel. The supply and spill chamber means adjacent to the head of the valve is in flow communication with a pressure equalization and spring chamber means at the opposite end of the valve via a passage through the valve and these chambers are in direct flow communication with a source of fuel at a relatively low supply pressure. During a pump stroke of the plunger, the solenoid can be energized, as desired, to push the pressure sensitive valve to a closed position relative to an associate valve seat so as to block flow from the pump chamber to the supply and spill chamber means thus allowing the plunger to effect pressurization of the fuel so as to effect discharge of fuel from the injection nozzle.