Vacuum Pump Stator Segmentation for Thermal Expansion
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Solution Overview
Problem
Conventional vacuum pumps face issues with reaction products depositing on the stator due to thermal expansion, causing heat loss and reduced efficiency in semiconductor and liquid crystal manufacturing processes.
Innovation Solution
A vacuum pump design featuring a cylindrical rotor, stator, and tubular base with radial gaps and positioning pins to prevent contact between the stator and base, allowing for controlled heating of the stator without direct contact, utilizing a heat insulation member to manage thermal expansion and maintain optimal temperature for preventing deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heater is embedded in the stator to directly heat the stator and increase its temperature to suppress deposition of reaction products, then the temperature of the stator is improved, but thermal expansion causes the clearance between the stator and base to decrease, leading to contact between the stator and base which causes heat loss and reduces the stator temperature
Solution Approach 1:
The invention divides the base into multiple sections: a fixed base portion and a movable base portion that can independently displace in the radial direction. This segmentation allows the movable base portion to follow the thermal expansion of the stator without causing contact, thereby preventing heat loss while maintaining the stator's operating temperature.
Solution Approach 2:
The invention introduces a dynamic element by making the movable base portion capable of radial displacement. This dynamic structure adapts to the thermal expansion of the stator during heating operations, maintaining an optimal gap that prevents both contact (heat loss) and excessive spacing (temperature maintenance issues).
2Manufacturing precision
If the stator is fixed to the base with a fitting structure having a clearance of approximately 0.1 mm to position the stator concentrically, then the positioning precision is improved, but thermal expansion reduces the clearance and causes the entire circumference of the shaft section to come into contact with the hole
Solution Approach 1:
The base is segmented into fixed and movable portions, allowing the movable portion to compensate for thermal expansion while the fixed portion maintains concentric positioning. This segmentation resolves the conflict between precise positioning and thermal expansion accommodation.
Solution Approach 2:
The invention changes the physical state of the base structure by introducing a movable portion that can change its radial position in response to temperature changes. This parameter change allows the system to adapt to thermal expansion while maintaining positioning accuracy.
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 effectively prevents contact between the high-temperature stator and low-temperature base, maintaining the stator's temperature and reducing heat transfer, thereby enhancing the vacuum pump's efficiency and longevity by minimizing thermal-induced contact.
Implementation Method 1
a heater embedded in the stator to directly heat the stator to increase the temperature of the stator
Implementation Method 2
the clearance becomes smaller due to thermal expansion
Implementation Method 3
heat of the stator having high temperature disadvantageously escapes to the base having low temperature to thereby decrease the temperature of the stator
Data Source
AI summary
A vacuum pump comprises a cylindrical rotor; a cylindrical stator which discharges gas in cooperation with the rotor; and a tubular base to which the stator is fixed. The stator has no fitting structure with respect to the base and is fixed to the base in a concentric state. A pin hole is formed on the stator and the base respectively, and a positioning pin for achieving the concentric state is inserted into each pin hole.