SINGLE STAGE ROOTS VACUUM PUMP AND VACUUM TYPE FLUID TRANSFER SYSTEM USING SINGLE STAGE ROOTS VACUUM PUMP

摘要

PROBLEM TO BE SOLVED: To provide a single stage Roots vacuum pump capable of inhibiting increase of an installation space, having good corrosion resistance, free from lessening of a pressure-feed flow rate and capable of shortening a discharge time when pressure feed is performed by reverse rotation, and to provide a vacuum type fluid transfer system using the single stage Roots vacuum pump.;SOLUTION: A pair of outdoor air introducing holes 22, 22 are formed in inner wall surfaces 6c in regions from an intermediate position p lying between a centre of each driving side Roots rotor shaft 11 and a center of a driven side Roots rotor shaft 12 to points q, q where internal circles situated on circumference extensions of the inner wall surfaces 6c of a casing 6 at symmetric positions near an imaginary line m to have a horizontally-long slit shape parallel in a casing width direction. A check valve 27 is attached to edges 26a, 26a of outdoor air introduction pipes 26, 26 respectively connected to outdoor air communication holes 24, 24 for inhibiting escape of air during reverse rotation of respective three lobe rotors 20, 21.;COPYRIGHT: (C)2007,JPO&INPIT