Pressure accumulation type of fuel injection device for an internal combustion engine

Claim 1

A pressure accumulation type of fuel injection device for an internal combustion engine, comprising: a body of a fuel injector, which is provided with spray holes and a pressure accumulation chamber in communication with a delivery port of a plunger pump through an inlet chamber, said body having a bore formed in an upper wall of the inlet chamber for a nozzle valve stem to extend slidably therethrough; a nozzle valve, which is biased towards the spray holes by a nozzle spring to selectively prevent flow of fluid through the spray holes, said nozzle valve having a valve stem which extends longitudinally through both the pressure accumulation chamber and the inlet chamber, an upper end portion of the valve stem extending hermetically and slidably through a bore of the fuel injector body; an annular projection, formed on the valve stem within the inlet chamber and having upper and under surfaces said under surface providing a valve seat; and a check valve, selectively fluidly separating said inlet and accumulation chambers, said check valve having a cylindrical valve body that encircles the valve stem of the nozzle valve while keeping a fuel passageway between said valve stem and check valve, said check valve being fitted hermetically and slidably within the injector body, the check valve being adapted to be sealingly biased against said under surface of the annular projection by a check valve spring provided between the check valve body and the nozzle valve stem to prevent flow of fuel between the inlet and accumulation chambers when a pressure of fuel in said accumulation chamber exceeds a pressure of fuel in said inlet chamber.