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Single-head varying pitch screw rotor with uniform tooth top width

A technology with equal addendum width and variable pitch, which is applied in the direction of rotary piston pumps, rotary piston machines, and components of pumping devices for elastic fluids, etc., which can solve the problem of reduced pumping rate and large overall backflow leakage , Weak inter-stage leakage blocking ability, etc.

Active Publication Date: 2012-12-05
NORTHEASTERN UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The addendum width of the existing single-head variable-pitch screw rotor profile gradually narrows from the suction end to the exhaust end, and the ability to block inter-stage leakage becomes weaker and weaker.
However, during the working process of the screw vacuum pump, the closer to the exhaust end, the greater the gas pressure and the pressure difference between the stages. The volume utilization coefficient of the pump is relatively small; and when the pressure difference between the stages at the exhaust end is large, the width of the tooth top becomes smaller, resulting in an unreasonable increase in the gas return flow
This directly leads to the small utilization coefficient of the suction volume of the screw vacuum pump and the large overall backflow leakage, which leads to the decrease of the main performance index of the screw vacuum pump, the ultimate vacuum degree and the actual pumping rate.

Method used

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  • Single-head varying pitch screw rotor with uniform tooth top width
  • Single-head varying pitch screw rotor with uniform tooth top width
  • Single-head varying pitch screw rotor with uniform tooth top width

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0046] This embodiment provides a single-head variable-pitch screw rotor with equal addendum width, and the end surface profile at a certain cross-section is as follows: figure 1 shown. The section of curve abc is the dedendum circle curve 1, the section of curve cde is the involute curve 2, the section of curve efg is the addendum circle curve 3, and the section of curve gha is the transition curve 4 composed of a single cycloid. (for example, the end c of the dedendum circle curve abc is connected with the start end c of the involute curve cde, the end e of the involute curve cde is connected with the start end e of the addendum circle curve efg, and the end of the addendum circle curve efg g is connected to the initial end g of the transition curve gha formed by a single cycloid, and the end of the transition curve gha formed by a single cycloid is connected to the initial end a of the dedendum circular curve abc to form an end profile).

[0047] The structural diagram of ...

Embodiment 2

[0050] This embodiment provides a single-head variable-pitch screw rotor with equal addendum width, and the end surface profile at a certain cross-section is as follows: image 3 As shown, the section of curve abc is the dedendum circle curve 1, the section of curve cde is the involute curve 2, the section of curve efg is the addendum circle curve 3, the section of curve gha is the transition curve 9 composed of double cycloid, and the four sections of curves are according to Sequential connection (for example, the end c of the dedendum circle curve abc is connected with the start end c of the involute curve cde, the end e of the involute curve cde is connected with the start end e of the addendum circle curve efg, and the addendum circle curve efg The end g of the transition curve gha formed by a single cycloid is connected to the initial end g of the transition curve gha formed by a single cycloid, and the end of the transition curve gha formed by a single cycloid is connecte...

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Abstract

A single-head varying pitch screw rotor with uniform tooth top width consists of a tooth root face, an oblique tooth face, a tooth top face and a transitional tooth face that are sequentially connected, wherein a rotor helical lead is linearly increased from an exhaust end to a suction end along with a helical angle of spread, so that the axial width of the oblique tooth face is gradually increased correspondingly, and the width of the tooth top face remains unchanged. Compared with the existing single-head varying pitch screw rotors, the molded line rotor has a relatively small tooth top face width at the suction end, so that a bigger interstage suction volume is formed, and the molded line rotor has the relatively big volume utilization rate, so that the bigger theoretic pumping speed is achieved under the same structural parameters; in contrary, the molded line rotor has the relatively bigger tooth top width at the exhaust end, has stronger interstage leakage resistance and can reduce the gas interstage leakage backflow rate, so that the improvement of the limit vacuum degree and the actual effective pumping speed of the vacuum pump are facilitated.

Description

technical field [0001] The invention relates to the technical field of screw type oil-free vacuum pumps, in particular to a single-head variable-pitch screw rotor with equal addendum width. Background technique [0002] The oil-free screw pump has the characteristics of wide pumping speed range, simple and compact structure, no friction in the pumping chamber components, long life, low energy consumption, and no oil pollution. It is widely used in semiconductor, pharmaceutical, food, chemical and other industrial fields. The screw rotor is the most critical pumping part in the screw vacuum pump, which directly determines the working performance and service life of the pump, and its manufacturing cost accounts for nearly half of the total cost of the screw pump. The profile design of the screw rotor is the most critical technology in the whole screw pump design. Among them, the single-head variable-pitch screw rotor, because of its internal pre-compression exhaust method, ha...

Claims

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Application Information

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IPC IPC(8): F04C29/00
CPCF04C18/084F04C18/16F04C2220/10F04C2230/21
Inventor 张世伟王德喜赵晶亮张志军
Owner NORTHEASTERN UNIV
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