Multi-fuel injector for an internal combustion engine, method for operating a multi-fuel injector and internal combustion engine

A multi-fuel injector (3) for an internal combustion engine for injecting at least a first and a second fuel into a combustion chamber of the internal combustion engine, the multi-fuel injector comprising:

• a base body (9) with
• a nozzle needle (11) movably disposed in the base body (9) so as to be movable between a first functional position, in which the nozzle needle (11) is biased toward a nozzle needle seat (13) provided in the base body (9) at one end of the nozzle needle (11) and including at least one injection bore (25) which is blocked by the nozzle needle (11) when the nozzle needle (11) is seated on the nozzle needle seat (13) and a second functional position spaced from the nozzle needle seat (13),
• a fuel collection chamber (23) formed around the nozzle needle seat (13) whereby a fluid connection between the fuel collection chamber (23) and the at least one injection bore (25) is established when the nozzle needle (11) is in the second functional position,
• a first inlet opening (19) In communication with the collection chamber (23) for supplying a first, gaseous fuel to the collection chamber (23),
• a position needle control chamber (27) arranged at an end of the nozzle needle (11) opposite the nozzle needle seat (13) and being in fluid communication with a second inlet (29) for supplying a pressurized second, liquid fuel to the control chamber (27) biasing the nozzle needle (11) into a closed position, and
• a needle position control chamber discharge line (39) provided with a control valve (37) disposed within the injector in communication with the needle position control chamber (27) and extending within the injector to the collection chamber (23) for a controlled release of the pressurized second, liquid fuel from the control chamber (27) to the collection chamber (23) thereby releasing the pressure in the needle position control chamber (27) to lift the nozzle needle (11) from the nozzle needle seat (13).