Roots vacuum pump is a rotary variable capacity vacuum pump without internal compression. It evolved from Roots blower. According to the different working pressure ranges of Roots pumps, they can be divided into dry Roots pumps with direct discharge to the atmosphere and wet Roots pumps, both of which are low vacuum Roots pumps. In addition, there are medium vacuum Roots pumps (mechanical booster pumps) and high-altitude multi-stage Roots pumps. So in this article, the editor will tell you the characteristics and principles of Roots vacuum pumps.

The characteristics of Roots vacuum pump:

1. There is a larger pumping speed within a wider pressure range.

2. The bypass relief valve can be activated at atmospheric pressure, thereby shortening the pumping time.

3. There is a gap between the rotors and the pump chamber wall, so the pump moves without friction, does not require lubrication, and there is no oil in the pump chamber.

4. The rotor has a symmetrical shape, good dynamic balance performance, stable operation, high gear transmission accuracy, and low noise during operation.

5. Compact in structure and occupying a small area, a horizontal structure is usually chosen, and the gas in the pump chamber flows vertically, which is conducive to the removal of dust or condensate during pumping.

6. High volumetric efficiency can be achieved by selecting appropriate rotor profiles and fine grinding.

7. Low operation and maintenance costs.

The principle of Roots vacuum pump:

Roots vacuum pump is a dual rotor positive displacement vacuum pump. There are two symmetrical rotor shapes in the pump chamber, with two, three, and four blades. The two rotors rotate in opposite directions to each other and are driven by the shaft end gear to rotate synchronously. The rotors are not in contact with each other, usually with a gap of 0.15-1.0mm, and the pump chamber is sealed by the gap.

Due to the lack of friction in the pump chamber of the Roots vacuum pump, the rotor can operate at high speed, usually at 1500-3000r/min, without the need for oil lubrication, and can achieve an oil-free and clean pumping process. The lubrication components of the pump are limited to bearings, gears, and dynamic seals. This pump does not have reciprocating components and can achieve good dynamic balance. Therefore, the Roots pump runs smoothly, has a high speed, a small volume, and can achieve a larger pumping speed.

Due to the continuous rotation of the rotor, the pumped gas enters the pump chamber from the suction port, is sealed inside the pump body of the suction chamber, and then discharged outside the pump through the exhaust port. Due to the fact that the gas sucked into the pump body space is not compressed, when the top of the rotor flips over the edge of the exhaust port, the pump body space is connected to the exhaust side. Due to the high gas pressure on the exhaust side, some high-pressure gas flows back into the pump body space, causing the pressure inside the pump chamber to suddenly rise to the exhaust pressure. This is the so-called external compression process. When the rotor continues to rotate, the pumped gas is discharged from the pump. The pumping process of the rotary pump is achieved through the continuous operation of two rotary pumps.