Patent ID: 7419103
Filing Date: 2008-09-02
Classification: F02M

Abstract:
1. A fuel injector for an internal combustion engine, having a nozzle needle that is guided in a nozzle body and acts on a nozzle needle sealing seat, and having a piezoelectric actuator and a hydraulic pressure boosting unit that has an actuator pressure boosting piston connected to the actuator and a nozzle needle pressure boosting piston connected to the nozzle needle, both of which pistons act on a coupler chamber located between the actuator pressure boosting piston and the nozzle needle pressure boosting piston and, depending on the pressure in the coupler chamber, the nozzle needle is lifted away from the nozzle needle sealing seat and thus highly pressurized fuel is injected from a high-pressure chamber into a combustion chamber of the engine, the improvement wherein the nozzle needle pressure boosting piston comprises a cylindrical chamber, a control piston axially guided in the cylindrical chamber and having a coupler chamber pressure surface exposed to the coupler chamber and having a differential pressure chamber pressure surface exposed to an inner differential pressure chamber contained in the cylindrical chamber, and the nozzle needle pressure boosting piston being associated with an outer differential pressure chamber that communicates via a hydraulic connection with the inner differential pressure chamber acting on the control piston.