| 摘要 |
<p>A screw vacuum pump (30), comprising a gas operating chamber formed of a male screw rotor (4) and a female screw rotor (5) having screw gears meshed with each other and having lead angles continuously varied according to the advancement of helix angles and a stator (13) storing these both rotors and a gas inlet (14) and a gas outlet (10) formed in the stator (13) to communicate with one end and the other end of the operating chamber. The male rotor (4) and the female rotor (5) further comprises variable lead screws formed so that the axially perpendicular cross-sectional shapes of the male screw rotor (4) and the female screw rotor (5) are varied according to a variation in continuous lead angle caused by the advancement of twisting or variable lead screws formed so that the axially perpendicular cross- sectional shape of one of the male screw rotor (4) and the female rotor screw (5) is set constant, the axially perpendicular cross-sectional shape of the other screw is varied, and an engaged clearance from a suction side to a discharge side is set constant.</p> |
