Dry screw vacuum pump varying pitch screw

Abstract

The invention discloses a dry screw vacuum pump varying pitch screw rotor which belongs to the technical field of dry vacuum pumps and is applicable to a dry screw vacuum pump, and winding turns>=3. A screw pitch (p) changes according to a wrapping angle (alpha), the screw pitch is the maximum at an air sucking end, namely a first local range (T1), and reaches a second local range (T2) after one turn. In the first local range, the screw pitch changes gradually within a small range or remains unchanged. In the second local range, the screw pitch becomes small gradually within a large range and reaches a third local range (T3) after one turn, and the screw pitch changes gradually within a small range or remains unchanged. A changing rule of a wrapping curve is controlled by fi (t), smooth transition of adjacent curves is guaranteed, and a corresponding varying pitch is controlled by f'i (t). The screw vacuum pump adopting the varying pitch screw rotor is the best choice for reducing energy demand, noise, working temperature, structural space and manufacture cost. An application field of the screw vacuum pump is wide.

Description

Technical field: [0001] The invention relates to a variable-pitch screw rotor of a dry screw vacuum pump, which is applied to a dry screw vacuum pump. Background technique: [0002] Equal-pitch screw vacuum pumps have the advantages of no oil, simple structure, no wearing parts, small maintenance workload, long life, etc., but they have large power consumption, large exhaust pulsation, large volume under the same exhaust volume and compression ratio, etc. Disadvantages, so the equal-pitch profile is difficult to apply to high-vacuum and large-displacement screw vacuum pumps, and the use of variable-pitch screw vacuum pumps has internal compression, which can reduce energy consumption, reduce structure, reduce noise, and reduce internal working temperature. , improve operational safety. [0003] The screw vacuum pump described in the patent document DE19745615A1 is divided into two poles by modifying the diameter of the addendum circle of the screw rotor, which plays the rol...

AI Technical Summary

Problems solved by technology

[0007] The patent document WO02 / 08609A1 describes a variable-pitch twin-screw rotor. The profile remains unchanged, the pitch goes from the smallest to the largest, then to the smallest, and finally remains unchanged. The description is biased towards the maximum pitch and minimum pitch of the screw rotor and the dynamics of the screw. Balanced, and the pitch at the beginning of the screw is designed to be the smallest, although the difficulty of dynamic balance design is reduced, but to a certain extent, the exhaust efficiency is reduced and the energy demand is increased

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