| The screw vacuum pump of this article is a new kind of rotational positive displacement pump,it is outstanding for its excellent efficiency, high vacuum, exhausting to the air directly, a long life, good sucking, reliable work,convenient maintenance, favorable dynamical balance,light vibration, no pressure fluctuate and noise,etc. The key part of an oil-free screw vacuum pump is a couple of rotors that clench each other, which is very important in the whole system. As intellectual property factors, screw rotor profile has been kept secret, did not fully open.Cycloid is a kind of profile between meshing screw, which can form a continuous contact line, and its seal performance is good, so the two kinds of profile’s design is based on cycloid. In this article I have focused on the research as following.Study on the composition of cycloid profile.Designing two kinds of new rotor profile, and describing composition of two kinds of profile’s side surface profile through principles of the cycloid curve. Using two kinds of rotor profile’s equations to verify conjugating meshing of profile.Then, based on the side surface profile equation to derive the rotor helical surface equation, and further derive the rotor shaft surface equation to describe the processing of the rotor. Using derived profile equation to construct rotor meshing three-dimensional map, and describing the composition of leak channels briefly.Study on geometric properties. Including calculation of the rotor using area,interdental area, the area utilization factor, leak triangle, and the volume between teeth, derivation of gometry formula pumping speed.Type line characteristics analysis.Based on rotor profile structure analysis and comparison of two new profiles’ performance, concludes the superiority of two new profiles.The method that deduces the equations of rotor end face profile is applicable to other rotor research of dry vacuum pumps, so it has a certain extent guide purpose. |
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