A self-balancing conical screw rotor with variable pitch

Abstract

The invention discloses a self-balancing variable-pitch cone-shaped screw rotor. The screw rotor is in a cone shape on the whole, tooth crest arc radiuses R1 and leads(P1, P2 and P3) of rotor bodies are gradually reduced from air sucking ends(I-I) to air discharging ends(VII-VII), and tooth root arc radiuses R3, tooth crest thicknesses(S1, S2 and S3) and tooth root thicknesses(T1, T2, T3) are gradually enlarged from the air sucking ends(I-I) to the air discharging ends(VII-VII); a cross section line of any axial position is variable, but all cross section lines are composed of component curves of same type and comprise 12 curves, and every two adjacent curves are completely smoothly connected. According to the self-balancing variable-pitch cone-shaped screw rotor, the sizes of working cavities of the air sucking ends can be efficiently increased, and the sizes of working cavities of the air discharging ends are reduced, so that the rotor bodies each have a large inner-size ratio, and the inter-class sealing performance of the air discharging ends and the strength of the rotor bodies are improved; and the form centers of the cross section lines in any axial position of each rotor body are all located at the rotating center line of the corresponding rotor body, and the dynamic balance performance of the rotor bodies is good.

Description

technical field [0001] The invention relates to a twin-screw vacuum pump, in particular to a self-balancing variable-pitch conical screw rotor suitable for the twin-screw vacuum pump. Background technique [0002] The twin-screw vacuum pump is a positive displacement vacuum pump, which is widely used in petrochemical, food, pharmaceutical, vacuum heat treatment, nano-manufacturing, and national defense technology fields because of its dry and oil-free suction cavity and stable and reliable operation; the core of the twin-screw vacuum pump The components are two screw rotors meshing with each other under synchronous counter-rotating double-rotation motion; the performance of the screw rotor and its cross-sectional profile directly affects the interstage sealing performance, mechanical properties and ultimate vacuum degree of the screw vacuum pump. [0003] The single-head conical screw rotor disclosed in patent CN101351646 has a large outer diameter at the suction end and a s...

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Problems solved by technology

[0004] In order to solve the eccentric force of the screw rotor in the above literature, the cusp of the section line, the large thickness of the tooth top at the suction end occupies the suction volume, and the small thickness of the tooth top at the exhaust end makes the gas pass through the interstage leakage of the tooth top surface. Bigger problem, in order to enrich the kind of screw rotor, the present invention proposes a kind of self-balancing variable-pitch conical screw rotor; screw rotor is conical, from suction end (I-I) to exhaust end (VII-VII), The lead of the screw rotor (P 1 ,P 2 ,P 3 ) gradually decreases, the thickness of the addendum (S 1 , S 2 , S 3 ) and root thickness (T 1 , T 2 , T 3 ) gradually increases, which can further increase the suction volume of the screw rotor at the suction end (I-I), and effectively prevent the screw rotor from passing through the teeth between two adjacent working chambers at the exhaust end (VII-VII). The interstage leakage on the top surface increases the strength of the screw rotor at the exhaust end (VII-VII) and reduces deformation; the cross-sectional profile of the screw rotor is completely smooth and can achieve correct meshing, eliminating The adverse effect of the rough connection point improves the stress condition of the screw rotor; at any axial position of the proposed screw rotor, its cross-sectional profile is S-shaped, and the centroid of the cross-sectional profile is at the rotation center of the screw rotor On the line, the screw rotor has good dynamic balance performance; the proposed screw rotor can increase the volume of the working chamber at the suction end, reduce the volume of the working chamber at the exhaust end, increase the internal volume ratio during the working process, and improve the Pumping speed and ultimate vacuum of twin-screw vacuum pump

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