Dynamic Characteristic and Performance Analysis of Claw Vacuum Pumps with Multi-Claw Rotors

The number of lobes of multi-claw rotors determines the performance of claw vacuum pumps including the pumping speed, dynamic characteristics, and operating conditions. In order to reveal the effects of the number of lobes on rotor performance, in this study, a geometric model of multi-claw rotors was established. The structure and geometric performance of multi-claw rotors including suction port and discharge port, pumping speed, and volumetric utilization ratio were compared. Furthermore, a dynamic characteristic model of claw rotors was established, and, therefore, axial gas forces, radial gas forces, and gas resistance torques of multi-claw rotors were obtained. The results indicate that double-claw rotors increased 34.67 % and 4.59 % in terms of pumping speed and volumetric utilization ratio compared to single-claw rotors, and triple-claw rotors showed similar increases as double-claw rotors. The triple-claw rotors have a 49.39 % and 31.38 % reduction in compression duration compared to the double-claw rotors and single-claw rotors. The gas resistance torques of the multi-claw right rotors are consistently more than that of the left rotors, which demonstrates that the multi-claw right rotors are more suitable to serve as the driving rotors. The research contents of this paper are of great theoretical significance for the selection of rotor lobes and the design of claw vacuum pumps with prominent dynamic characteristics.