Fuel injection valve

Claim 1

In a fuel injection valve for use in an internal combustion engine, said fuel injection valve being of the type effecting initial injection and main injection and including a nozzle holder, a nozzle supported by said nozzle holder and having a nozzle needle slidably fitted therein, a first movable spring seat supported by said nozzle needle, a first stationary spring seat disposed at a side of said first movable spring seat remote from said nozzle, a first spring interposed between said first movable spring seat and said first stationary spring seat and determining a valve opening pressure for said initial injection, a second movable spring seat disposed at a side of said first stationary spring seat remote from said nozzle and having a rod member extending therefrom toward said nozzle and disposed in spaced and opposed relation to said first movable spring seat, a second stationary spring seat disposed at a side of said second movable spring seat remote from said nozzle, and a second spring interposed between said second movable spring seat and said second stationary spring seat and determining a valve opening pressure for said main injection, the improvement comprising a first spring chamber in which said first spring is fitted, a stepped portion having an end face facing toward said nozzle and serving as said first stationary spring seat, a second spring chamber in which said second spring is fitted, a threaded hole, said first spring chamber, said stepped portion, said second spring chamber, and said threaded hole being formed in said nozzle holder and consecutively arranged in the mentioned order, said nozzle holder having a reference surface at an end portion thereof remote from said nozzle, a set screw threadedly fitted in said threaded hole, said set screw having a contact surface disposed in contact with said reference surface, said set screw having an end face facing toward said nozzle and serving as said second stationary spring seat, a first shim interposed between said first spring and said end face of said stepped portion and determining the setting force of said first spring, a second shim interposed between another end face of said stepped portion remote from said nozzle and said second movable spring seat and determining a lifting amount through which said nozzle needle lifts for said initial injection, and a third shim interposed between said second spring and said end face of said set screw and determining the setting force of said second spring, said reference surface being used for measurement of distances between said reference surface and portions of said fuel injection valve in order to determine at least a desired sum of the setting forces of said first and second springs and a desired lifting amount through which said nozzle needle lifts for said initial injection.