FUEL INJECTOR

The invention relates to a fuel injector for injecting fuel into a combustion chamber of an internal combustion engine, comprising a nozzle body (1) and a nozzle needle (2) which is displaceably received for releasing and closing at least one injection opening (3) in a high-pressure bore (4) of the nozzle body (1) and is acted upon in the direction of a sealing seat (5) by the spring force of a nozzle spring (6), furthermore comprising a piezo actuator (7) which is hydraulically coupled to the nozzle needle (2) via a coupling device (8) for controlling the stroke movement of the nozzle needle (2), wherein the coupling device (8) compensates for an axial offset between a longitudinal axis (A1) of the nozzle needle (2) and a longitudinal axis (A2) of the piezo actuator (7) and reverses the direction of action of the piezo actuator (7). According to the invention, the coupling device (8) for reversing the direction of action of the piezo actuator (7) comprises a coupler piston (9) which has an actuator-side hydraulic working surface (10) for delimiting an actuator-side coupler volume (14) and a nozzle-side hydraulic working surface (11) for delimiting a nozzle-side coupler volume (13) and is traversed by an axial bore (15) for connecting the two volumes (13, 14).