Check valve for injecting gas

A check valve for injecting fuel, comprising:

• an elongate body having a through-hole formed along a longitudinal direction of the body, wherein a first neck-down portion having an outer diameter smaller than other areas is formed at an intermediate portion of the body in the longitudinal direction thereof, and a fuel flow hole is formed at the first neck-down portion;
• a coupling ring coupled to an upper end of the body, wherein the coupling ring is configured to fix the body to a prechamber;
• a coil spring installed inside the coupling ring;
• an elongate spindle slidably installed inside the through-hole of the body and inside the coil spring in the coupling ring, wherein a second neck-down portion having an outer diameter smaller than other areas is formed at a lower end portion of the spindle;
• a spring seat inserted into an annular gap formed between an upper end portion of the spindle and an upper end portion of the coupling ring, wherein the spring seat is fixed with the upper end portion of the spindle and slidable with the spindle inside the upper end portion of the coupling ring;
• and
• a spacer, which is coupled to a lower end of the body, for fixing the lower end of the body that covers an outer edge of the spindle to the prechamber,
• wherein an O-ring is provided in the upper end portion of the spindle to contact an inner surface of the through hole of the body.