For a long time, there are many difficulties and challenges in the development of double stage slide valve vacuum pump in our country. The production of 2H-150 and other products took more than 20 years after the standard was formulated. In fact, the design and manufacture of double stage slide valve vacuum pump with large pumping speed will encounter a series of problems, such as dynamic balance, control of two-stage oil supply, noise reduction and so on. However, the double stage slide valve vacuum pump with large pumping speed has a very wide application prospect in use. This paper introduces the necessity of the development of the high pumping speed double stage slide valve vacuum pump and the design characteristics of the successfully developed 2H-150 slide valve vacuum pump, and puts forward the necessity of developing the double stage slide valve vacuum pump with higher pumping speed.

Due to the structural characteristics, the capacity of the slide valve pump is much larger than that of the rotary vane pump. Because the slide valve vacuum pump can work in poor vacuum environment for a long time, it is often used in large vacuum equipment. The limit pressure of single-stage pump is between 0.6 PA and 1.3 PA (gas shut-off) and that of double-stage pump is 0.06 PA.

Pumping speed ≥ 150L / s can be regarded as a large-scale slide valve pump. For a long time, there are only 70L / s two-stage slide valve pump in China. However, if there is a double-stage slide valve vacuum pump with high pumping speed, it is particularly beneficial to simplify the unit structure of vacuum equipment, reduce power consumption, achieve energy-saving effect, simplify operation and improve control reliability. Taking the successful design and development of 2H-150 double stage slide valve vacuum pump as an example, the necessity of developing large-scale double stage slide valve vacuum pump is introduced in this paper. At the same time, by introducing the characteristics of double cylinder design structure of 2H-150 double stage slide valve vacuum pump, the possibility of realizing the dynamic balance of double cylinder structure of double stage slide valve vacuum pump in large pumping speed structure is put forward, and the realization of double stage slide valve vacuum pump under high pressure (2PA) is put forward ）The possibility of obtaining high pumping speed. At the same time, the possibility that the simplified structure design is beneficial to the start-up and control of single pump is put forward.

1. Significance of developing double stage slide valve vacuum pump with large pumping speed

For a long time, slide valve vacuum pump and roots slide valve vacuum unit are widely used in large vacuum equipment under certain vacuum degree (1 ~ 10-2Pa). According to incomplete statistics, the output value of slide valve vacuum pump and roots slide valve vacuum unit in Zhejiang province exceeds 400 million yuan. However, because there is no double stage slide valve vacuum pump with high pumping speed, it is necessary to design roots roots roots slide valve unit in many configurations of roots slide valve unit, or the use of a two-stage slide valve pump can achieve the purpose of use, and the slide valve roots can be used to meet the requirements of vacuum degree. For example, when the limit vacuum is 10-2 PA and the pumping speed is 150 l / s, the main pump must be zj-150 roots pump, and the front stage pump can be 2h-30 slide valve pump. However, in use, sometimes we hope to have a high pumping speed when the pressure is strong. Obviously, using the 2h-30 pump as the front stage pump can not meet this requirement, so we have to match the 2h-70 pump as the front stage pump, but some users still can not meet the requirements of high pumping speed under higher pressure, so the strange phenomenon that the main pump is zj-150, and the user requires the front stage pump to be equipped with h-150 slide valve pump. At the same time, we analyze the structural characteristics of roots pump, it can be clearly seen that the pumping speed of the so-called roots pump is completely affected by the pumping speed of the front stage pump. The limit pressure of roots pump is mainly determined by the limit pressure of the front stage pump. Only when the limit pressure of the front stage pump is low can roots pump obtain a lower limit pressure. Since there was no double stage slide valve vacuum pump with high pumping speed in the past, it is necessary to design roots roots roots slide valve unit based on increasing roots pump to meet and improve the vacuum degree, which undoubtedly increases the complexity of the structure. Therefore, when summarizing the application of roots unit, authoritative data put forward that when the inlet pressure is very low (PA < 10-2 HPA) and the front stage pump air ballast valve works, the double-stage front stage pump is usually used, otherwise the required pressure of roots pump is difficult to reach. Moreover, under this pressure, the pumping speed of the front stage pump becomes too low, which will lead to high compression ratio and low volumetric efficiency. At present, roots vacuum pump has developed into 5000 l / s, 10000 L / s and 20000 L / S. in many cases, both high pumping speed and low limit pressure are required. Obviously, single-stage slide valve vacuum pump can not meet this requirement. Developing double stage slide valve vacuum pump with high pumping speed can certainly simplify the structure, achieve energy saving and reliable control.

But the development of double stage slide valve vacuum pump will encounter many technical difficulties The company, represented by the company, develops single-stage and double-stage slide valve vacuum pump with three cylinder structure as the main body. This structure has good dynamic balance effect. There is no need to add counterweight on the belt pulley and balance wheel. Although the centrifugal inertia force on the slide valve rod is not balanced, it is not enough to generate large vibration due to the small interference force of this centrifugal inertia force, so from the perspective of balance It is a good structural form. However, because the three cylinder structure needs two middle walls, it is difficult for the middle cylinder to supply oil. At the same speed, its structure design volume is too large. Therefore, according to investigation, the largest double stage slide valve vacuum pump produced by Kinny company is ktc-112 pump with pumping speed of 51 L / s and limit pressure of 3 × 10 - 2 PA. According to the technology of Kinny company, gktc-225 pump produced by general company in UK has the maximum pumping speed of 104 L / s and the limit pressure of 3 × 10 - 2 PA. In order to develop double stage slide valve vacuum pump with high pumping speed, Shanghai Shengong, Zhejiang Taizhou global, Jiangsu Haizhen, Zhejiang Taizhou Lixin and Zhejiang vacuum equipment company have successively developed 2h-120, 2H-150 and 2h-230