Fuel injection valve for preliminary and principal injection

摘要

A fuel injection valve assembly for supplying a preliminary injection of fuel of a constant amount regardless of engine speed before the main injection of fuel begins comprising a spring biased, fuel supply pressure responsive, preliminary injection piston for the preliminary injection, a fuel supply pressure responsive loading piston for controlling the main injection fuel flow and a needle valve, both of the latter being biased oppositely by a common spring. Separate supply ducts for the preliminary and main fuel injections and the arrangement of the valve surfaces on the loading piston and needle valve enable the loading piston to be held closed and the needle valve to be opened by the pressure imposed on the preliminary injection piston and remain open long enough for the preliminary injection piston to travel its full stroke before closing and before the needle valve is opened for the main injection.