Double-injection type fuel injection valve

Claim 1

A fuel injection valve comprising: an injection nozzle having a nozzle needle liftable in response to fuel pressure; a nozzle holder supporting said injeciton nozzle; a first nozzle spring and a second nozzle spring arranged within said nozzle holder; a first movable spring seat supporting said first nozzle spring; a second movable spring seat supporting said second nozzle spring, said second movable spring seat having one end disposed in facing relation to said first movable spring seat and adapted to have said one end spaced from the latter by a predetermined gap when said nozzle needle is in a seated position thereof; whereby lifting of said nozzle needle from said seated position thereof causes corresponding lifting of said first movable spring seat against the force of said first spring through a lift determined by said predetermined gap to effect an initial injection, and further lifting of said nozzle needle causes said first movable spring seat to urgingly displace said second movable spring seat against the combined force of said first and second springs to lift said second movable spring seat to effect a main injection; a spacer removably fitted in a bore formed in an end face of said nozzle holder remote from said injection nozzle, said spacer having an inner end face urgingly engaging said first nozzle spring to impart urging force to said first movable spring seat; a hollow threaded member having an internal space and removably threadedly fitted in said nozzle holder at a location outward of said spacer and disposed in tight contact with said spacer to retain same in place; said second movable spring seat having an enlarged portion arranged within said internal space of said hollow threaded member in facing relation to an outer end face of said spacer and a rod portion extending integrally from said enlarged portion and slidably fitted through an axial through bore formed in said spacer; said second nozzle spring being arranged within said internal space of said hollow threaded member and urging said second movable spring seat toward said first movable spring seat; a first shim interposed between said spacer and said first nozzle spring for adjusting the setting load of said first nozzle spring; and a second shim interposed between said enlarged portion of said second movable spring seat and said spacer for adjusting said predetermined gap for initial injection lift between said first movable spring seat and said second movable spring seat.