Fuel injector with two control chambers separately controllable by a servo valve unit

The fuel injector (10) has an inner and an outer control chamber (12,13) for the control of an inner (20) and an outer (22) nozzle needle respectively. The two control chambers are sealed in relation to one other by an upper matched needle guide (16) for the inner nozzle needle. The outer control chamber has a first nozzle spring (21) to press the inner nozzle needle against its valve seat located in the lower section of the nozzle body (23).