Vacuum Pump Rotor Gap Design for Corrosion and Performance
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Solution Overview
Problem
Existing vacuum pumps for semiconductor, flat-panel display, and solar panel manufacturing face performance degradation due to increased gaps between rotary and stator members, which can lead to contact and deterioration of corrosion protection coatings, or complicate the structure with axial movement mechanisms.
Innovation Solution
A vacuum pump design featuring a cylindrical member with lower thermal expansivity or creep rate than the circular member, with a gap configuration where the non-joint portion gap is narrower than the joint portion gap, and a taper-shaped boundary between them, preventing contact and maintaining anti-corrosion characteristics while improving performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gap between the rotary member and stator member is made narrow to improve pump performance, then pump performance is improved, but the risk of contact between members increases and corrosion protection coatings deteriorate
Solution Approach 1:
The rotary member is divided into two distinct parts: a circular member made of aluminum alloy and a cylindrical member made of a material with lower thermal expansivity and creep rate. This segmentation allows each part to serve a specific function - the circular member provides rotational drive while the cylindrical member maintains a stable, narrow gap with the stator member, preventing contact and coating deterioration.
Solution Approach 2:
Different materials are used for different parts of the rotary member based on local requirements. The circular member uses aluminum alloy for ease of rotation, while the cylindrical member uses a material with lower thermal expansivity and creep rate specifically at the gap-critical region to maintain dimensional stability and prevent contact with the stator member.
2Productivity
If the gap between the rotary member and stator member is made narrow to improve pump performance, then pump performance is improved, but the structure becomes complicated due to axial movement mechanisms
Solution Approach 1:
The rotary member is segmented into a circular member and a cylindrical member, eliminating the need for complex axial movement mechanisms. The cylindrical member's material properties inherently maintain the gap, simplifying the overall structure while improving performance.
Solution Approach 2:
The invention changes the material parameter (thermal expansivity and creep rate) of the cylindrical member to achieve gap stability. By selecting a material with lower thermal expansivity and creep rate, the gap remains narrow and stable without requiring additional control mechanisms, thus simplifying the structure.
3Reliability
If the gap between the rotary member and stator member is increased to prevent contact, then reliability is improved, but pump performance deteriorates significantly
Solution Approach 1:
The cylindrical member is specifically designed with material properties (lower thermal expansivity and creep rate) tailored for the gap-critical region. This local quality ensures the gap remains stable and narrow where it matters most, maintaining both reliability and pump performance.
Solution Approach 2:
The invention changes the material parameters of the cylindrical member to achieve optimal gap dimensions. By using a material with lower thermal expansivity and creep rate, the gap is maintained at a narrow, performance-optimizing dimension while preventing contact, thus resolving the contradiction between reliability and productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design allows for a narrow gap between the rotating cylindrical member and stator, enhancing pump performance without compromising anti-corrosion properties or structural complexity, effectively preventing contact and maintaining efficient operation.
Implementation Method 1
the cylindrical member is made of a material having at least a feature of lower thermal expansivity or lower creep rate than that of a material of the circular member
Implementation Method 2
the cylindrical member is made of a material having at least a feature of lower thermal expansivity or lower creep rate than that of a material of the circular member
Implementation Method 3
the gap being set in consideration of thermal expansion and creep of the rotary member that are caused due to centrifugal force generated by rotation of the pumps
Data Source
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AI summary
The present invention provides a vacuum pump suitable for improving pump performance, and a rotor thereof. In this vacuum pump, a gap between a rotating cylindrical member and a stator member around an outer circumference of the cylindrical member can be set as narrow as possible without deteriorating the anti-corrosion characteristics of the internal structure of the vacuum pump or complicating the entire structure of the vacuum pump, and the narrow gap contributes to the improvement in vacuum pump performance. The rotor of the vacuum pump has a circular member that is driven rotatably, a cylindrical member joined to an outer circumference of the circular member, and a thread groove pump flow path formed between the cylindrical member and a stator member surrounding an outer circumference of the cylindrical member. The cylindrical member is made of a material having at least a feature of lower thermal expansivity or lower creep rate than that of a material of the circular member. a gap of a second region provided between a non-joint portion of the cylindrical member and the stator member is set to be smaller than a gap of a first region provided between a joint portion of the cylindrical member and the stator member.