Standalone Drag Pump for High-Temperature Vacuum Systems
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Solution Overview
Problem
Turbomolecular pumps face challenges in operating effectively at higher pressures due to condensation issues in the drag pump stage, which limits their temperature operation and requires costly, large-diameter piping and heating for backing pumps, making them unsuitable for clean room environments.
Innovation Solution
A separate drag pump with magnetic bearings, fabricated from steel, operating at temperatures above 130°C, which allows for higher temperature and pressure operation, reducing the need for large-diameter piping and heating, and incorporating regenerative stages to achieve higher exhaust pressures, thus reducing the number of backing pumps required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the drag pump stage is integrated within the turbomolecular pump and uses aluminium rotor, then the pump can operate at high tip speeds with good strength to weight ratio, but the pump cannot operate at temperatures above 130°C due to loss of aluminium strength
Solution Approach 1:
The pump is divided into two separate units: a turbomolecular pump for high vacuum operation and a standalone drag pump for backing operation. This segmentation allows each pump to be optimized independently - the turbomolecular pump maintains its aluminium rotor for high-speed operation while the standalone drag pump can use steel rotor for high-temperature operation above 130°C.
Solution Approach 2:
The drag pump stage is extracted from the integrated turbomolecular pump design and positioned as a separate standalone unit. This extraction allows the drag pump to be constructed from steel material capable of withstanding temperatures above 130°C without compromising the turbomolecular pump's high-speed performance characteristics.
2Object-affected harmful factors
If remote backing pumps are used outside the clean room, then condensation issues are avoided, but large-diameter piping and heating infrastructure are required which increases cost
Solution Approach 1:
The drag pump is merged with the turbomolecular pump system by positioning it immediately adjacent to the turbomolecular pump exhaust within the clean room environment. This combination eliminates the need for long external piping and extensive heating infrastructure, as the drag pump exhaust is directly connected to the turbomolecular pump inlet through a short interface.
Solution Approach 2:
The drag pump acts as an intermediary device positioned between the turbomolecular pump and the external environment. It handles the backing pump function locally within the clean room, preventing process gas condensation in long external pipes by maintaining the exhaust stage temperature above the dew point without requiring extensive external heating infrastructure.
3Temperature
If the drag pump operates at higher pressures, then condensation of process by-products increases, but using steel rotor allows operation above 130°C to prevent condensation
Solution Approach 1:
The material parameter of the rotor is changed from aluminium to steel in the standalone drag pump. This parameter change enables the drag pump to operate at temperatures above 130°C, maintaining the exhaust stage temperature above the dew point of process by-products and preventing condensation even at higher operating pressures.
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 solution enables a cost-effective, high-temperature drag pump suitable for clean room operation, reducing piping and heating costs while maintaining semiconductor process gases above condensation temperatures, allowing for smaller pipe diameters and potentially eliminating the need for additional backing pumps.
Implementation Method 1
magnetic bearings for rotatably mounting said rotor using magnetic levitation within said pump
Implementation Method 2
said pump comprises a heater configured to heat said drag pump such that said at least a portion of said rotor and stator component configured to contact said gas to be pumped are maintained at a temperature above 130° C. during operation
Data Source
AI summary
A drag pump for pumping gas and a set of vacuum pumps including the drag pump are disclosed. The drag pump comprises: a rotor configured to rotate within a stator component and to drive a gas to be pumped from a gas inlet to a gas outlet; magnetic bearings for rotatably mounting the rotor within the pump; wherein at least a portion of the rotor and stator component configured to contact the gas to be pumped are configured for operation at temperatures above 130° C.