Patent ID: 7422006

Claim:
A fuel injector, comprising: a valve-closure member cooperating with a valve-seat surface to form a sealing seat; one of a piezoelectric actuator and a magnetostrictive actuator which activates the valve-closure member; a hydraulic coupler which includes a master piston and a slave piston, wherein a coupler volume exists between the master piston and the slave piston, and wherein the master piston and the slave piston are axially displaceable with respect to each other, and wherein the coupler volume is connected to a compensating chamber via a throttle; a flexible section which at least partially delimits the compensating chamber; and at least one spring element which one of directly and indirectly exerts pressure on the flexible section from outside the coupler volume, via fixed components; wherein: the coupler volume, the throttle and the compensating chamber are filled with a hydraulic medium; and the spring element is braced on the master piston via a sleeve-shaped holder, and wherein the sleeve-shaped holder is fixed in place on the master piston in an immovable manner.