| 摘要 |
PURPOSE:To provide a large closing force and enhance airtightness, by preventing the force of a valve-closing spring from acting on a valve body in the operating range of an adjusting spring for exerting a valve-opening force. CONSTITUTION:The valve-closing spring 42 for exerting a closing force on the valve body 24 is a tension spring, is connected to a shaft 31 through an engaging and stopping member 43 provided with a play not smaller than the stroke of the valve body 24, and is hooked by a lever 44 moved in conjunction with the rotation of a cam 38, thereby constituting a link mechanism with a grooved piece 45. When the lever 44 is moved concurrently with the rotation of a motor 36 to reduce the displacement of the spring 42 so that the spring 42 exerts no force, a pressure-adjusting spring 33 starts to be displaced in accordance with the displacement of a slidable pin 39, and starts to exert a force on the valve body 24. |
