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 an internal combustion engine, the multi-fuel injector comprising:

• a base body (9) with
• a nozzle needle (11) movably disposed in the base body 15, (3) between a first functional position, in which the nozzle needle (11) is biased toward a 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,
• a first inlet opening 19 in a communication with the collection chamber (23) for supplying a first fuel to the collection chamber (23),
• a control chamber (27) arranged at an end of the nozzle needle opposite the valve seat (13) and being in fluid communication with a second inlet (29) for supplying a pressurized second fuel to the control chamber (27), and
• a control chamber discharge line (29) provided with a control valve (37) in communication with the control chamber (27) for a controlled release of the pressurized fluid from the control chamber (27).