双螺杆真空泵封闭容积间压力和泄漏特性研究

Study on the characteristic of leakage and pressure within the lead of two screw vacuum pump

研究了双螺杆泵转子封闭容积间泄漏过程,推导出双螺杆泵在达到极限真空时平均泄漏量、内部平均压力的计算方程。计算结果表明:螺杆上不同封闭容积之间的泄漏量和压力相差很大。随着转子周边各间隙的减小,吸气端的泄漏量和压力迅速减小,排气端则相对平缓;螺杆各封闭容积间,通过圆周间隙的泄漏量与通过径向间隙、齿侧间隙泄漏量之和的差值随着转子各间隙的减小而减小。当转子间间隙小于一定值时,通过径向间隙和齿侧间隙的泄漏量会大于通过圆周间隙的泄漏量。

To study the leakage performance about the sealing volumes of rotors, we deduced the calculation equations of the av-erage leakage and pressure in two screw vacuum pump at its ultimate vacuum The results show that leakage and pressure in each vessel vary widely. With the decrease of rotor clearance, the leakage and pressure reduce quickly in the inlet and gently in the outlet. The difference of the leakage, which is caused by the circumferential clearance and the sum of the radial and tooth flank clearance, is also falling with the decrease of each rotor clearance. When rotor clearance is less than a certain value, the leakage caused by radial and tooth flank clearance may be greater than that caused by circumferential clearance.