Turbomolecular Pump Cooling Element for Rotor Thermal Management
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Solution Overview
Problem
Turbomolecular pumps experience significant rotor heating due to inadequate thermal contact between the rotor and stator with the housing, leading to elevated temperatures that can damage the pump and reduce its service life.
Innovation Solution
Incorporating a cooling element that protrudes into the flow path upstream of the pre-pump stage, designed to enhance thermal coupling with the housing by having a larger contact area and higher thermal conductivity than the pump-active elements, thereby reducing the rotor temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rotor operates at high speed above 10,000 revolutions per minute, then the pumping efficiency is improved, but the rotor temperature increases to 90°C and above leading to potential damage
Solution Approach 1:
A cooling element is introduced as an intermediary component between the rotor and the housing. This cooling element conducts heat away from the rotor to the housing, serving as a thermal mediator that enables heat transfer without direct thermal contact between the rotor and housing, thus cooling the rotor while maintaining high-speed operation
Solution Approach 2:
The patent replaces direct thermal contact (mechanical thermal coupling) with a dedicated cooling element that provides thermal coupling through conduction. Instead of relying on direct contact between rotor and housing for heat transfer, a separate cooling element with optimized thermal properties is used to substitute the inadequate thermal contact path
2Productivity
If the rotor and stator are designed with minimal contact to the housing, then the pumping performance is maintained, but thermal coupling is insufficient leading to rotor overheating
Solution Approach 1:
The housing is segmented into distinct functional zones: a cooling element contact area for thermal management and a rotor/stator operation area for pumping performance. This segmentation allows the cooling element to be positioned where it can effectively transfer heat to the housing without interfering with the rotor and stator pumping elements, thus maintaining both pumping performance and thermal management
3Temperature
If a cooling element is added to improve heat transfer, then the rotor temperature is reduced, but the device complexity increases
Solution Approach 1:
The cooling element is designed to serve multiple functions: it provides thermal coupling between the rotor and housing for heat transfer, structurally supports the rotor assembly, and defines part of the flow path geometry. By making the cooling element multi-functional, the patent reduces the need for separate dedicated cooling components, thus limiting the increase in device complexity while achieving effective rotor cooling
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
The cooling element effectively reduces the rotor temperature by improving heat transfer to the housing, extending the turbomolecular pump's service life and maintaining pumping efficiency with minimal structural modifications.
Implementation Method 1
The cooling element is designed to transfer a greater amount of heat to the housing of the turbomolecular pump over a predetermined period of time than the respective pumping elements
Data Source
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AI summary
A turbomolecular pump comprises a casing, several turbomolecular pump stages, and at least one backing stage located downstream of the turbomolecular pump stages. Furthermore, the turbomolecular pump has a flow path for the pumped gas, which is defined section by the pump-active elements of the turbomolecular pump stages and the backing stage. The turbomolecular pump also includes a cooling element that extends into the flow path upstream of the backing stage. The cooling element is designed to transfer a greater quantity of heat to the casing of the turbomolecular pump than the respective pump-active elements of the turbomolecular pump stages over a predetermined period.