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以单头等螺距内凹转子双螺杆真空泵为研究对象,对螺杆真空泵工作时转子与泵腔、转子与转子之间气体的流动状态进行研究,将周向返流简化为两平面平板之间库埃特流动与泊肃叶流动,径向和齿侧返流简化为薄壁孔流动,建立了螺杆真空泵转子周向、径向和齿侧返流量计算的理论数学模型。计算分析了不同间隙值以及螺杆转子参数对螺杆真空泵返流量的影响,得到螺杆真空泵返流量随着螺杆渐开线基圆半径、大径、小径、和导程变化的规律。研究结果表明:周向间隙的增加使得返流量显著增加;在理论抽速给定的条件下,小径大径比为0.63时,返流量最小。
Taking the single-head equally-pitch concave rotor twin-screw vacuum pump as the research object, the gas flow between the rotor and the pump chamber, the rotor and the rotor during the operation of the screw vacuum pump was studied, and the circumferential backflow was simplified as the Cohen between the two flat plates The special flow and Poiseuille flow are simplified, and the radial and flank flows are simplified as thin-walled flow. The theoretical mathematical model for the calculation of the circumferential, radial and flank flows of the screw vacuum pump rotor is established. The influence of different clearances and parameters of screw rotor on the return flow of screw vacuum pump was calculated and analyzed. The law of the return flow of screw vacuum pump changed with the radius, diameter, diameter and lead of screw involute base. The results show that the increase of the circumferential clearance leads to a significant increase of the backflow. When the ratio of the diameter to the diameter is 0.63, the amount of back flow is the smallest when the theoretical pumping speed is given.