High pressure fuel injection device for engine

Claim 1

An accumulator type of injection nozzle comprised of an accumulator chamber to be supplied with high pressure fuel, a nozzle port leading from said accumulator chamber, an injector valve movable between a closed position and an opened position for controlling the discharge of fuel from said accumulator chamber through said nozzle port, a control chamber for receiving pressurized fuel, an actuating member supported for movement within said control chamber and associated with said injector valve for retaining said injector valve in its closed position when said control chamber is pressurized and for movement of said injector valve to its opened position when pressure is relieved in said control chamber, and relief valve means moveable between a closed position for maintaining pressure in said control chamber and an opened position for relieving said control chamber for effecting fuel discharge through said nozzle port, the improvement comprising said nozzle comprising an outer housing defining cavity, an electromagnet within said cavity for moving said relief valve to one of said positions when said electromagnet is energized, said electromagnet being comprised of an armature surrounded by a winding, a yoke surrounding said winding and having an intermediate portion in proximity to one end of said winding and extending inwardly toward said armature for forming a flux path between said intermediate portion and said armature through said relief valve when said winding is energized, said yoke having a first portion spaced inwardly from said outer housing within said cavity and extending around said winding and a mounting portion having an outer surface fixed relative to said outer housing and extending from one end of said winding and around said relief valve, said mounting portion being connected to said intermediate portion by a connection having means for reducing flux leakage from said intermediate portion to said outer housing.