| 摘要 |
PURPOSE:To prevent unburnt gas from discharging at the re-opening of flow passage by a structure wherein an opening retarding means and a small quantity supply valve are provided. CONSTITUTION:When a valve drive shaft 8 is pushed down to re-open the flow passage, the shaft 8 will not go down further beyond the midway position retarded by the opening retarding means 54. The pressure in a supply pressure chamber 20 is raised by the inflow of gas from the upstream side of a shut- off valve 18 through the small quantity supply valve 60 and a throttle passage 57, resulting in raising a diaphragm boss 23 so as to exactly confront the ball escape groove 32 of the diaphragm boss 23 with a ball 28 and consequently to make further pushing-down of the valve drive shaft 6 possible. When the ball escape groove 30 exactly confronts with the ball 28 by further pushing-down of the valve drive shaft 6, the shut-off valve 18 is open, resulting in quickly raising the pressure in the supply pressure chamber 20 in order to raise the diaphragm boss 23 up to its extreme position and to push the ball 28 into the ball escape groove 30. In such a manner as mentioned above, the shut-off valve 18 is held at its open state. |
