Fuel injector having fuel-filled damping chamber

Claim 1

A fuel injection nozzle for internal combustion engines comprising a nozzle body, a valve seat integral with said nozzle body, and a valve needle displaceably supported in said nozzle body at an injection opening, said valve seat being monitored by said valve needle injection opening in the fuel flow direction, a closing spring in a first chamber for loading said valve needle, a fuel inflow line arranged to discharge into said first chamber, a second chamber upstream from said first chamber, a dividing wall means separating said second chamber from said first chamber and including a blocking shoulder in said second chamber, said valve needle including an end extension piston that extends with radial clearance through said dividing wall means into said second chamber, a cap including a blind bore bottom positioned on said end extension piston and arranged in said second chamber, a damping chamber formed by said cap, said blind bore bottom of said cap and an end face of said end extension piston, a throttle conduit in said cap adapted to lead away from and to said second chamber into said damping chamber, a restoring spring in said second chamber, acting on the cap for shifting the cap against said blocking shoulder on said dividing wall means, said cap arranged to rest on said blocking shoulder no later than after a first pre-stroke of the valve needle, and said end extension piston of the valve needle includes a cross section which is smaller than a cross section of said piston enclosed by said valve seat.