Abstract: An electromagnetic valve includes a tubular valve member fitted on a cylindrical guide member for sliding movement therealong. The guide member has an axial introduction passage leading to a valve seat of the valve member via a communication passage. When the valve member is disengaged from the valve seat, a high-pressure fluid in the introduction passage is spilled into a low pressure chamber provided around the guide member. The electromagnetic valve is incorporated in a unit fuel injector so as to control the spilling of the fuel pressurized by a pump mechanism. In the unit fuel injector, the pump mechanism, the electromagnetic valve and an injection nozzle mechanism are mounted on a linearly-extending body and disposed on the axis of said body. A plunger of the pump mechanism and a nozzle of the injection nozzle mechanism extend along the axis of the body. The electromagnetic valve is disposed between the pump mechanism and the injection nozzle mechanism.

Abstract: A unit fuel injector includes a body, the body having a fuel supply and return chamber, a fuel supply passage communicating with the chamber, and a drain passage communicating with the chamber. The body is provided with a pump mechanism, an injection nozzle mechanism for injecting high pressure fuel from the pump mechanism, and an electromagnetic valve mechanism for escaping the high fuel pressure from the pump mechanism. The electromagnetic valve mechanism include a poppet-type valve member. Immediately when a head of the valve member is disengaged from a valve seat facing the fuel supply and return chamber, the pressurized fuel within the pump mechanism is spilled or fed to the fuel supply and return chamber. The unit fuel injector further includes an auxiliary valve mechanism for opening and closing the drain passage. The auxiliary valve mechanism includes a valve port at one end of the drain passage, and when the head of the valve member abuts against a stop portion of the body, the valve port is closed.

Abstract: A unit fuel injector includes a body. The body incorporates a pump mechanism, an injection nozzle mechanism for injecting fuel fed thereto from the pump mechanism, and an electromagnetic valve mechanism for relieving high pressure fuel from the pump mechanism. The electromagnetic valve mechanism includes a poppet-type valve member. Immediately when an abutment portion of the valve member is disengaged from a valve seat during a pump stroke, the pressurized fuel is spilled into a spill chamber from the pump mechanism. The fuel injector further includes a mechanism for propelling the valve member in such a direction that said abutment portion is moved away from the valve seat, utilizing the spill fuel pressure. The propelling mechanism includes a bore formed in said body, and a flange provided on a stem portion of the valve member, the flange being slidably fitted in the bore to divide the bore into a pressure introduction chamber and a low pressure chamber along the axis of the valve member.