Vibration sound reducing device, and process for assembling elastic membrane in vibration sound reducing device

Abstract

A through-bore is provided in an outer wall of a passage defining structure defining a liquid passage faced by at least a portion of a vibration generating section, and opens at its inner end into the liquid passage. A vibration absorbing device includes an occluding member mounted to the outer wall to occlude the through-bore, an elastic membrane with its one end facing the liquid passage and other end facing a space defined between the elastic membrane and the occluding member, and a retaining member mounted to the occluding member for retaining the elastic membrane between the retaining member and the occluding member. Thus, a variation in pressure of a liquid in the liquid passage which is induced by the vibration generated in the vibration generating section is absorbed by flexing of the elastic membrane, whereby an exciting force applied from the liquid to the passage defining structure is effectively reduced, and a vibration sound radiated from the passage defining structure is reduced. Moreover, it is possible to suppress the increase in weight of the passage defining structure due to the mounting of the vibration absorbing device to a small level to the utmost. In addition, it is possible to avoid reduction in the sealability due to the liquid pressure in the liquid passage or due to the deterioration of the elastic membrane, and the elastic membrane can be reliably retained between the occluding member and the retaining member to ensure a sufficient sealing.