Patent ID: 7993113

Claim:
A damper configured to restrain the propagation of vibrations produced in a vacuum pump to a vacuum system during evacuation of the vacuum system by the vacuum pump via gas transfer by a gas transfer mechanism in the vacuum pump by means of the rotating action of a rotating body in the vacuum pump, the damper comprising: a first vibration absorbing member having a spring constant and a mass and being configured for arrangement between the vacuum system and the vacuum pump, and a second vibration absorbing member having a spring constant and a viscosity damping coefficient and being configured for arrangement between the vacuum system and the vacuum pump with sufficient clearance from the first vibration absorbing member so as to prevent the first and second vibration absorbing members from coming into contact with one another during an evacuation operation by the vacuum pump, the spring constants, mass and viscosity damping coefficient of the first and second vibration absorbing members being so set such that the first and second vibration absorbing members form a notch filter-type vibration isolator having a damping characteristic in a frequency band that coincides substantially with a rotation frequency of the rotating body of the vacuum pump; wherein the first vibration absorbing member comprises a thin-wall cylindrical member the peripheral surface of which is of a bellows shape, and the second vibration absorbing member comprises an elastic member disposed at an outer periphery of the thin-wall cylindrical member, the elastic member being configured so as to confront and surround only a portion of an outer periphery of the thin-wall cylindrical member.