Gas injection valve for gas engine

Claim 1

A gas injection valve for injecting gas into a combustion chamber of a gas engine, said injection valve comprising: an injection valve body having a nozzle chamber with nozzle holes for thus injecting fuel gas into a combustion chamber, means forming a first gas passage for introducing fuel gas into said body, and means forming a second gas passage having an upstream end communicable with said first gas passage and a downstream end communicable with said nozzle chamber; a first needle valve disposed between said first and second gas passages for closing and opening communication therebetween; a second needle valve disposed between said second gas passage and said nozzle chamber for closing and opening communication therebetween; actuating means for applying forces respectively for urging said first and second needle valves in the closing direction thereof; hydraulic actuating means for applying forces respectively urging said needle valves in the opening directions thereof; and means for, upon said second needle valve being prevented from closing, whereby said second gas passage is exposed to the reduced pressure of the combustion chamber, automatically moving said first needle valve to the closed position thereof and thereby preventing further supply of fuel gas to said nozzle holes, said automatic moving means comprising said first needle valve having at an extreme tip end thereof a pressure receiving face which is disposed within said second gas passage and exposed to the pressure therein in the closed position of said first needle valve, and said force applied by said actuating means to move said first needle valve in said closing direction thereof being greater than the sum of said reduced pressure in said second gas passage and said force of said hydraulic actuating means to move of said first needle valve in said opening direction thereof.