Evaluating the Interlobe Clearance and Determining the Sizes and Shapes of All the Leakage Paths for Twin-Screw Vacuum Pump

Abstract

The maximum sphere method and the minimum cross-section method are proposed to calculate the interlobe clearance between two mating screw rotors and to determine the shapes and sizes of all the leakage paths. These two methods are inspired by the red-lead and tooth-contact pattern and can be used to evaluate the interlobe leakage and to design the mating rotor profiles. The combined results of these two methods provide the basis for an exact evaluation of the fluid leakage, and this feature increases flexibility in geometrical designing and manufacturing of the screw rotors. These methods are also suitable for non-conjugate rotors and contribute to thermal analysis and optimum programming.