Patent ID: 7500648

Claim:
A fuel injector, comprising: a valve seat surface of a sealing seat; a valve-closure member cooperating with the valve-seat surface; one of a piezoelectric actuator and a magnetostrictive actuator that activates the valve-closure member; a throttle; a hydraulic coupler that includes a master piston, a slave piston and a coupler volume formed in-between, wherein the coupler volume communicates with a compensating chamber by way of the throttle; a compression spring braced on at least one of the slave piston and the master piston at least one of directly and via a fixed component; and an elastic flexible section at least partially delimiting the compensating chamber; wherein: the coupler volume, the throttle, and the compensating chamber are filled with a hydraulic medium; the flexible section exerts a pressure on the hydraulic medium due to prestressing; a force of the compression spring is directed with an initial stress in such a way that the force enlarges the coupler volume; the slave piston has a cup-shaped first slave section that includes a base partially delimiting the coupler volume; the master piston partially surrounds the first slave section in the shape of a cup; and the throttle is arranged in the base of the cup-shaped first slave section.