Fuel injection valve

The fuel injector valve (1) has a fuel channel (22) running from a threaded connector (4) to a chamber surrounding an electrical actuator (2). This may be a piezoelectric, electrostrictive or magnetostrictive actuator. It presses on a valve closure needle (8) in the hollow tip (12,13) of the nozzle which sprays fuel directly into combustion chamber. The top of the actuator presses on a spring-loaded (20) coupling piston (24) sliding in the top portion (23) of the injector. There is a gap (32,25) between the piston and the cylinder joining the cylinder space (36) to an equalization chamber (14) with a flexible membrane (27). There is a spring-loaded (19) ball valve (18) in the piston.