Large two-stroke compression-ignited internal combustion engine with fuel injection system for low flashpoint fuel and a fuel valve therefore
A large two-stroke turbocharged compression-ignited internal combustion crosshead engine with a plurality of cylinders has at least one pressure booster for each cylinder for boosting fuel pressure, two or more electronically controlled fuel valves for each cylinder with an inlet of the two or more electronically controlled fuel valves being connected to an outlet of the at least one pressure booster. An electronic control unit is connected to the at least one pressure booster and the two or more electronically controlled fuel valves. The electronic control unit is configured to determine a start time for a fuel injection event, activate the at least one pressure booster ahead of the determined start time and pen the two or more electronically controlled fuel valves at the determined start time.
1. A fuel valve for injecting low flashpoint liquid fuel into the combustion chamber of a large slow running two-stroke turbocharged self-igniting internal combustion engine, said fuel valve comprising:
an elongated valve housing with a rear end and a front end,
a nozzle with a plurality of nozzle holes, said nozzle being disposed at the front end of said elongated valve housing,
a fuel inlet port in said elongated valve housing for connection to an external source of pressurized low flashpoint fuel,
an actuation fluid port in said elongated valve housing for connection to an external source of actuation fluid,
an axially displaceable valve needle slidably received in a longitudinal bore in said fuel valve, said valve needle having a closed position and an open position and said valve needle being biased towards said closed position,
said valve needle allowing flow of fuel from a fuel cavity to said plurality of nozzle holes when the valve needle is in its open position and said valve needle preventing flow of fuel from said fuel cavity to said plurality of nozzle holes when the valve needle is in its closed position, a pump piston received in a first bore in said valve housing with a pump chamber in said first bore on one side of said pump piston,
an actuation piston received in a second bore in said valve housing with an actuation chamber in said second bore on one side of said actuation piston, said pump piston being connected to said actuation piston to move in unison therewith,
said actuation chamber being connected to said actuation fluid port,
said pump chamber having an outlet fluidically connected to said fuel cavity and an inlet fluidically connected to said fuel inlet port,
a sealing liquid inlet port for connection to an external source of pressurized sealing liquid,
a conduit connecting said sealing liquid inlet port to a clearance between said first bore and said pump piston for sealing said pump piston in said first bore,
a conduit connecting said sealing liquid inlet port to a clearance between said longitudinal bore and said valve needle at a first position along the length of said longitudinal bore for sealing said valve needle in said longitudinal bore,
a conduit connecting the low flashpoint fuel inlet port to said longitudinal bore at a second position along the length of said longitudinal bore, said second position being closer to said fuel cavity than said first position.
2. A fuel valve according to claim 1 , wherein said valve needle rests on a valve seat in said closed position and said valve needle has lift from said valve seat in said open position.
3. A fuel valve according to claim 1 , wherein said nozzle has a nozzle body that is secured to the front of said elongated valve housing.
4. A fuel valve according to claim 2 , wherein said valve seat is located in the tip of said nozzle.
5. A fuel valve according to claim 3 , wherein said longitudinal bore is formed at least partially in said nozzle body.
6. A fuel valve according to claim 1 , wherein lift of said valve needle is controlled by the fuel pressure.