Fuel gas injection valve, dual-fuel gas engine, and fuel gas injection method

A fuel gas injection valve applicable to a dual fuel gas engine capable of burning both fuel oil and fuel gas by using high-pressure injection, the fuel gas injection valve comprising:

• a holder including a first injection hole through which fuel gas is injected to produce premixed fuel when a piston included in the dual fuel gas engine is positioned between 40° and 100° before top dead center, and a second injection hole through which fuel gas is injected to produce diffusion fuel when the piston is positioned between 10° before the top dead center and 15° after the top dead center;
• a first needle valve that slidably reciprocates along an axial direction in the holder to close the second injection hole when the first injection hole is opened, and to open the second injection hole when the first injection hole is closed;
• and
• a second needle valve having a sealing face on the top thereof, the sealing face being brought into contact with a needle valve seat provided in the holder, and the second needle valve reciprocating in the holder along the axial direction to prevent fuel gas from circulating to the first injection hole and the second injection hole when the sealing face is in contact with the needle valve seat, and to allow the fuel gas to circulate to the first injection hole or the second injection hole when the sealing face is separated from the needle valve seat.

A method for injecting fuel gas using a fuel gas injection valve applicable to a dual fuel gas engine capable of burning both fuel oil and fuel gas by using high-pressure injection,

• wherein the fuel gas injection valve includes:
• a holder including a first injection hole through which fuel gas is injected to produce premixed fuel when a piston included in the dual fuel gas engine is positioned between 40° and 100° before top dead center, and
• a second injection hole through which fuel gas is injected to produce diffusion fuel when the piston is positioned between 10° before the top dead center and 15° after the top dead center;
• and
• a first needle valve that slidably reciprocates along an axial direction in the holder;
• a second needle valve having a sealing face on the top thereof, the sealing face being brought into contact with a needle valve seat provided in the holder, and the second needle valve reciprocating in the holder along the axial direction,
• wherein the method comprises:
• closing the second injection hole by the first needle valve when the first injection hole is opened and opening the second injection hole by the first needle valve when the first injection hole is closed;
• and
• preventing fuel gas from circulating to the first injection hole and the second injection hole by the second needle valve when the sealing face is in contact with the needle valve seat and allowing the fuel gas to circulate to the first injection hole or the second injection hole by the second needle valve when the sealing face is separated from the needle valve seat.