Abstract: An electromagnetic unit fuel injector for use in a diesel engine includes a pump, in the form of a cam actuated plunger reciprocable in a bushing, to supply fuel at high pressure to a variable volume pressure accumulator chamber and through a flow control orifice to a control chamber in supply flow communication with a fuel injection nozzle assembly having a pressure actuated injection valve controlling the injected charge of fuel from the unit. Flow through the control orifice into the control chamber is selectively controlled by an electromagnetic valve assembly which also selectively controls flow from the control chamber through a drain orifice to a low pressure fuel return or drain line.

Abstract: An electromagnetic unit fuel injector for use in a diesel engine has a pump including a cam actuated plunger reciprocable in a bushing for intensifying the pressure of fuel delivered to a pressure actuated injection valve controlling flow discharge out through a spray outlet, to a pressure accumulator and, through a throttling orifice passage into one end of a modulation pressure control chamber having a spring biased piston movable therein, the piston engaging one end of the injection valve, this one end of the pressure control chamber downstream of the throttling orifice passage being connected by a conduit, including a solenoid actuated valve controlling flow through a metering orifice to a low pressure fuel drain return line whereby the pressure of fuel in the pressure control chamber acting on the piston is modulated so as to control the seating and unseating of the injection valve.

Abstract: 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.

Abstract: An electromagnetic unit fuel injector for use in a diesel engine has a pump, provided by a cam actuated plunger reciprocable in a bushing, for intensifying the pressure of fuel delivered to a spring biased closed, pressure actuated injection valve controlling flow discharge out through a spray outlet, to a pressure accumulator and through a throttling orifice passage into one end of a modulation pressure control chamber having an enlarged diameter stem portion of the injection valve therein, the modulation pressure control chamber downstream of the throttling orifice passage being connected by a conduit including a solenoid actuated valve controlling metering orifice with a low pressure fuel drain return line whereby the pressure of fuel in the modulation pressure control chamber acting on the enlarged diameter stem portion of the injection valve is modulated so as to control the seating and unseating of the injection valve.