| 摘要 |
<p>PURPOSE:To reduce the use amount of purge gas, by forming a purge gas annular groove for introducing purge gas, in a shaft piercing section, and by forming a discharge gas annular groove for leading discharge gas between the purge gas annular groove and a pump mechanism. CONSTITUTION:A purge gas annular groove 11 for introducing purge gas, is formed in a section of a casing 1 through which a drive shaft 4 pierces, on the motor casing 8 side, so that the purge gas annular groove 11 surrounds around the outer periphery of the drive shaft 4, and a discharge gas annular groove 13 for introducing discharge gas is formed between the purge gas annular groove 11 and a pump mechanism 100. With this arrangement, it is possible to reduce the pressure deferential across the purge gas annular groove 11, thereby it is possible to remarkably reduce the supply amount of purge gas.</p> |
