Dry compressing spindle vacuum pump with contra-rotating rotor pair has inlet side rotor pitch producing nominal displacement capacity first increasing to maximum value and then changing with constant drop to outlet side pitch

摘要

The dry compressing spindle vacuum pump with a contra-rotating rotor pair with rotor pitch changing along the rotor from a larger suction side pitch (mein) to a smaller outlet side pitch (maus). The inlet side rotor pitch along the rotor axis producing the nominal displacement capacity first increases to a maximum value (mmax) and then changes with a constant drop to the outlet side pitch value. The maximum pitch change and the minimum pitch change are selected with equal magnitude.