What is a positive displacement vacuum pump

Claw vacuum pump is not only a positive displacement vacuum pump, but also a dry vacuum pump. Next let EVP vacuum pump manufacturers continue to talk about the principle and characteristics of claw vacuum pump.

Claw vacuum pump type:

Claw vacuum pump, like roots vacuum pump and screw vacuum pump, is non-contact dry vacuum pump. In general, in order to achieve a certain compression ratio, speed and dynamic balance, claw vacuum pump is usually composed of multi-stage claw rotor in series or roots rotor and multi-stage claw rotor in series. At present, the common three-stage claw rotor plus one-stage roots rotor, or four-stage claw rotor in series, the performance of roots plus claw type is generally better than that of full claw type claw vacuum pump.

In the multi-stage claw vacuum pump, it can be divided into screw type, reverse claw type and spiral reverse claw type according to the different rotor form, phase difference and diaphragm, and their performance is also different.

For claw vacuum energy, the higher the rotating speed, the larger the compression ratio. In general, the rotation number of claw vacuum pump is mostly 3000r / min, and the limit pressure is 1-10pa.

Claw vacuum pump operation principle:

1. Exhaust port; 2. Rotor; 3. Pump body; 4. Air inlet

Claw vacuum pump in the process of repeated, to achieve the purpose of pumping.

Claw vacuum pump structure features:

1、 The structure of claw vacuum pump

In practice, the claw vacuum pump is multi-stage type, the rotor pair is installed on two parallel shafts, and the different stages need to be separated into separate pump chambers by interstage partition, and equipped with suction and exhaust channels, so the structure is complex.

2. Characteristics and application of claw vacuum pump

In the process of describing the operation principle, we have learned that the claw vacuum pump can compress the gas in operation, and the rotor has the function of opening and closing the valve automatically in the process of rotation, which can achieve high compression ratio and volume efficiency, and ensure high pumping speed under low power consumption. The type of the pumped gas has little influence on the compression ratio, and the clearance between the rotor and the pump body can also ensure the smooth removal of small particles.

Generally speaking, claw vacuum pump has the following main characteristics:

(1) There is no lubricating oil medium and oil return in the pump cavity;

(2) Clean air extraction, no pollution to the extracted container and gas, the extracted gas can be recycled, consumption reduction and emission reduction;

(3) The air flow in the pump chamber moves vertically, and a small amount of particles and liquids are easily removed under the action of gravity;

(4) The extraction element is non-contact type, which can realize high-speed operation;

(5) The rotor pair is suspended in the pump cavity, the rotor pair is not in contact with the pump cavity, there is no friction, and the service life is long.

However, due to the existence of diaphragm between stages, and the independent existence of each pump cavity, the multi-stage claw vacuum pump also has the disadvantages of long and curved air flow channel, difficult assembly and disassembly of rotors and shafts at all stages, and complex treatment of clearance between rotors and diaphragm between stages and pump body.

As a dry vacuum pump, claw vacuum pump can be used in semiconductor, chemical industry, nuclear industry, film, instrument, medicine, biopharmaceutical, food and other fields, and can be used as a gas delivery pump.