| 摘要 |
PURPOSE:To prevent production of gas due to vacuum of an insulating material for covering the wire material of a stator and to shut off suction of the gas to the interior of a casing, by a method wherein a can is inserted in the inner periphery of a stator for securing, and outer gas is prevented from mixing in vacuum atmosphere in a casing. CONSTITUTION:A can 21 is engaged in a manner to make contact with the inner peripheral surface of a stator 17, an insertion end 22 is pressed against a rubber plate 28 engaged with the inner surface of a motor case 6, and outer end 23 is pressed against an outer peripheral ring 30 of a bearing 16. this constitution enables prevention of production of outer gas to the inner periphery of the stator 17 resulting from suction of the negative pressure of the insulating material of the stator 17 and mixing of the outer gas in vacuum atmosphere in the casing 1. This constitution is adapted for the peculiar action of a root type vacuum pump with a built-in motor, prevents final arrival at a vacuum desired value and mixing of outer gas, being impure gas, in, for example, the carbonic acid gas circulating circuit of a carbonic acid gas laser oscillator, and enables production of an effect in that purity of carbonic acid gas is prevented from being damaged.
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