三轴罗茨真空泵的抽气理论和结构设计

Design of Single-Stage Three-Axis Roots Vacuum Pump and Its Pumping Mechanism

新兴行业的不断兴起给真空泵带来了快速发展的机遇,同时也对真空泵的集成化、高效率、节约空间、高技术含量提出了更高的要求。本文提出了一种三轴式的罗茨真空泵,对其抽气过程进行了介绍,并基于啮合原理,给出了一种典型的四叶圆弧型转子的型线方程。通过对抽气过程的建模分析,在抽气效率、压缩比、旋转应力和热变形等方面,与常规的双轴式罗茨真空泵进行了对比。计算和模拟结果表明,在空间尺寸增加不多的情况下,三轴式罗茨真空泵具有接近两倍的抽速、良好的压缩比和更好的动平衡特性的特点,具有较好的技术优势和发展前景。

The single-stage three-axis Roots vacuum pump was developed by modifying the conventional twoaxis Roots pump. In the newly-developed Roots pump,the two driven rotors,installed on both sides of the active rotor,are capable of sucking in and discharging air simultaneously. The profile equations of the circular arc,four-lobe rotors and formula of its pumping speed were derived based on the gearing principle. The characteristics of the old and new rotors,including but not limited to the rotating strength,thermal deformation,pumping efficiency and compression ratio,were empirically approximated,mathematically modeled,theoretically analyzed and numerically simulated in finite element method. The calculated and simulated results show that the novel pump significantly outperforms the conventional one. To be specific,in addition to higher dynamic stability,lower noise and more uniform stress,the novel pump has higher zero-flow compression-ratio and nearly two times higher pumping-speed than those of the conventional one.