Importance

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Abstract

In the case of a vacuum pump, having a screw groove, of the present invention, a rotor is disposed inside a stator with an extremely small clearance provided in-between, under which condition the rotor is designed to rotate at a high speed. The upper and lower end faces of the aforementioned stator are supported with sliding members interposed in-between, thereby enabling the stator to perform sliding rotation. Between the stator and a pump housing is provided a clearance r. In the event that stress corrosion cracking occurs to the rotor, then part of the rotor comes into contact with the stator, thereby causing the stator to be deformed radially outward. Even when such deformation takes place, the stator rotates together with the rotor, since the clearance r is provided on the outside periphery of the stator, with the result that consequent rotational friction causes the rotor to decelerate. Therefore, even when stress corrosion cracking occurs to the rotor, it is possible to prevent the housing from being fractured.

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First Claim