Evaluating the inter-lobe clearance of twin-screw compressor by the iso-clearance contour diagram (ICCD)

A mathematical procedure is proposed to calculate the inter-lobe clearance between two mating screw rotors, and then represent the clearance field by iso-clearance contour diagram (ICCD). The theory of gearing and the tooth contact analysis (TCA) have been applied to solve the geometrical and kinematic relations of mating rotors. The contact line and the approximate blowhole can be obtained by TCA. However, it is insufficient to describe the inter-lobe leakage. By inspecting the ICCD, we can find all possible inter-lobe leakage paths, not just the contact line and the blowhole. The benefit of utilizing ICCD is that it can also be modeled by a single mathematical model such as the cubic spline interpolation instead of the mathematical model of the multi-segment tooth profiles. Hence, this method avoids the problem of discontinuity and divergence in optimal programming.