| 摘要 |
PURPOSE:To reduce noise, provide high durability and facilitate the manufacturing of the titled device by a method wherein a base plate and a backing plate are formed by a vibration-proof alloy having a high coefficient of dampening action. CONSTITUTION:Since a base plate 14 and a backing plate 17 are formed of a vibration-proof alloy having a high coefficient of reducing of vibration, it is possible to reduce an amplitude of vibration of the base plate 14 and the backing plate 17 caused by a vibrating force added to the base plate 14 and the backing plate 17 under a striking action with the valve sheet 20. In this way, since the base plate and the backing plate are formed by a vibration-proof alloy having a high coefficient of reduction in vibration, it is possible to decrease a striking sound of the flapper valve against the valve seat and to improve an effect of reducing noise and at the same time it is possible to improve a durability and facilitate the manufacturing of the unit. |
