Plunger-Activated Unit Injector for Internal Combustion Engines: 6,227,174

An electronically controlled unit injector for internal combustion engine. The unit injector is mounted on a cylinder and has a plunger that extends into the combustion chamber. Fuel flow through the unit injector is accomplished by the plunger, which moves upward into the unit injector in response to upward motion of the piston. This motion displaces fuel and pressurizes a fuel path within the unit injector, including a pressure void at the tip of the needle. The pressurized fuel lifts the needle, which permits fuel to exit through injection spray holes into the combustion chamber.