Electromagnetic unit fuel injector

An electromagnetic unit fuel injector including a housing means having a fuel passage means connectable at one end to a source of fuel for the ingress or egress of fuel at a suitable supply pressure, a supply chamber and a spill chamber positioned in spaced apart relationship to each other and in flow communication with said fuel passage means, a pressure relief passage interconnecting said chambers and a valve stem guide bore extending between said chambers with a conical valve seat encircling said guide bore at the spill chamber end thereof;

• a pump cylinder means in said housing means;
• an externally actuated plunger reciprocable in said cylinder means to define therewith a pump chamber open at one end for the discharge of fuel during a pump stroke and for fuel intake during a suction stroke of said plunger;
• said housing means including a valve body having a spray outlet as one end thereof for the discharge of fuel;
• an injection valve means movable in said valve body to control flow from said spray outlet, a discharge passage means connecting said pump chamber to said spray outlet;
• and a solenoid actuated, poppet valve controlled passage means for effecting flow communication between said pump chamber and said fuel supply chamber and including a solenoid actuated poppet valve having a head with a stem extending therefrom journaled in said valve guide bore for reciprocable movement whereby said head is movable between an opened position and a closed position relative to said valve seat, said stem having a reduced diameter stem portion next adjacent said head which defines with said valve stem guide bore an annulus portion of said valve controlled passage means;
• and, a solenoid means operatively connected to said housing means, said solenoid means including an armature and a spring positioned in said supply chamber and operatively connected to said poppet valve with said spring positioned to normally bias said poppet valve to said open position.