Patent ID: 7066400

Claim:
In a fuel injection system for internal combustion engines, the system having a fuel injector that can be supplied from a high-pressure fuel source and that has an injection valve with injection nozzles pointing toward a combustion chamber, coaxial inner and outer nozzle needles assigned to the injection nozzles, the coaxial inner and outer nozzle needles being triggerable as a function of pressure to open and close various injection cross sections at the injection nozzles, each nozzle needle being assigned a respective damping piston, the damping pistons being movable relative to one another and acting on at least one fuel-filled chamber which communicates with a low-pressure return system via an outlet throttle, the improvement wherein the fuel-filled chamber forms a damping chamber ( 50 , 71 , 81 ) for the damping piston ( 41 , 43 ); a closing chamber ( 29 ) to which an end face ( 37 ) of the outer nozzle needle ( 11 ) is exposed that acts in the closing direction; the closing chamber ( 29 ) communicates with the low-pressure return system ( 35 ) via a closing chamber throttle ( 31 ); and the outlet throttle ( 54 ) has a greater throttling action than the closing chamber throttle ( 31 ).