A fuel valve for injecting gaseous fuel into a combustion chamber of a self-igniting internal combustion engine and method

A fuel valve (50) for injecting gaseous fuel into the combustion chamber of a large two-stroke low-speed turbocharged self-igniting internal combustion engine, said fuel valve (50) comprising:

• an elongated fuel valve housing (52) with a rear end and a front end,
• a nozzle (54) with a plurality of nozzle holes (56) opening to a sac volume (55) inside the nozzle (54), said nozzle (54) being disposed at the front end of said elongated valve housing (52), said nozzle (54) comprising a base (51) and an elongated nozzle body, said nozzle (54) being connected with its base (51) to said front end of said elongated valve housing (52), said nozzle (54) having a closed tip (59) with said nozzle holes (56) arranged close to said tip (59),
• a gaseous fuel inlet port (53) in said elongated fuel valve housing (52) for connection to a source (60) of high pressure gaseous fuel,
• an axially displaceable valve needle (61) slidably received in a longitudinal bore (77) in said elongated valve housing (52), said axially displaceable valve needle (61) having a closed position and an open position,
• said axially displaceable valve needle (61) rests on a valve seat (69) in said closed position and said axially displaceable valve needle (61) has lift from said valve seat (69) in said open position,
• said valve seat (69) being placed between a fuel chamber (58) and an outlet port (68),
• said fuel chamber (58) is fluidly connected to said gaseous fuel inlet port (53),
• said outlet port (68) is fluidly connected to said sac volume (55) in said nozzle (54),
• an actuator system for controllably moving said axially displaceable valve needle (61) between said closed position and said open position,
• an ignition liquid inlet port (78,98) for connection to a source of high pressure ignition liquid (57), and
• an ignition liquid supply conduit (76,99) connecting said ignition liquid inlet port (78,98) to said fuel chamber (58), said ignition liquid supply conduit (76,99) including a fixed flow restriction,
• said fixed flow restriction being configured to throttle the flow of ignition liquid from said ignition liquid inlet port (78,98) to said fuel chamber (58) in order to allow a small amount of ignition liquid as a constant flow of ignition fluid through said fixed flow restriction to accumulate in the fuel chamber (58) above the valve seat (69) when the valve needle (61) rests on the valve seat (69).