| 摘要 |
PURPOSE:To lengthen the life of a mirror and to reduce the consumption of a laser gas while eliminating the need for a gas recycling device by forming a bypass between an oil chamber for a root blower and a gas inlet section for the root blower. CONSTITUTION:When gas pressure in each of rotor sections 21 and an oil chamber 24 for a root blower 2 is represented by Pr and Poil, not only vaporish oil 23 but also mist-shaped masses of oil 23 mix into the rotor sections 21 through a shaft seal 29 and contaminate a laser gas because Poil and Pr are approximately the same on the operation of the root blower 2 when there is no bypass 26. When the bypass 26 is formed, on the contrary, oil 23 hardly leaks in through the shaft seal 29 from the oil chamber 24 because Poil is lower than Pr. However, vaporish oil 23 leaks through the bypass section 26 to a gas inlet section 27 for the root blower 2 though quantity thereof is extremely small. Accordingly, oil filters 28 are installed on its midway of the bypass 26. |
