| 摘要 |
<p>A prestage gas compressor assembly (3) comprises a drive side screw rotor (11), and two sets of flat driven side screw rotor (12, 13) meshing to intersect the drive side screw rotor (11) perpendicularly from the opposite sides. The rotor outline of the drive side screw rotor (11) when it is cut along a plane including the central axis is defined by a concave curve such that the outside diameter increases gradually from the gas suction side toward the gas delivery side. In the concave curve, the distance from the central axis of the drive side screw rotor (11) to a point on the concave curve and the distance from the center of each driven side screw rotor (12, 13) to that point are identical or kept at a fixed ratio. A cooling fan (115) is formed integrally at the axial end face of the drive side screw rotor (11) on the delivery side. A small air-cooled volume type oil free screw gas compressor of simple structure can thereby be attained.</p> |
