| 摘要 |
<p>A Roots pump rotates a plurality of rotors (23-32) by a pair of rotary shafts (19, 20) to draw gas. Each rotary shaft (19, 20) extends through a rear housing.member (14) of the Roots pump. An annular shaft seal (49, 50, 49A) is fitted around each rotary shaft (19, 20) and is received in a recess (47, 48, 66) formed in the rear housing member (14). A labyrinth seal (57, 58, 68, 70) is located between an end surface of each shaft seal (49, 50, 49A) and the bottom of the associated recess (47, 48, 66). A resin layer (59, 60, etc.) is firmly attached to the end surface of each shaft seal (49, 50, 49A). As a result, oil is reliably prevented from leaking into a pump chamber (39-43). <IMAGE> <IMAGE></p> |
