Turbomolecular Pump Rotor Bore Structure for Stable Multi-Chamber Vacuum
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Solution Overview
Problem
Existing turbomolecular pumps face challenges in achieving efficient vacuum generation across multiple vacuum chambers with varying pressure levels, particularly due to the design and balance of rotating components, which can lead to increased complexity and cost.
Innovation Solution
The rotor design features a deep bore with a large inner diameter relative to the shaft, shifting the center of gravity to enhance stability and load distribution, and standardized rotor disk assemblies with identical groups to simplify assembly and reduce component variability, along with optimized bearing arrangements to balance the rotor effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the rotor shaft is designed with a deep bore and large inner diameter to reduce weight and shift center of gravity, then the rotor's moment of inertia decreases and stability improves, but the structural strength and rigidity of the shaft may be compromised
Solution Approach 1:
The rotor shaft is constructed using composite materials, specifically a hollow shaft design where the outer shell provides structural strength while the hollow interior reduces weight. This composite structure allows the shaft to maintain adequate strength and rigidity despite the deep bore configuration, resolving the contradiction between weight reduction and strength maintenance.
2Adaptability or versatility
If multiple vacuum chambers are connected to intermediate inlets in the pumping direction, then different pressure levels are achieved in each chamber, but the pump system complexity increases
Solution Approach 1:
The pump system is segmented into multiple independent pumping stages, each capable of handling different pressure ranges. The rotor includes multiple rotor disks with pump-active surfaces that create distinct compression stages, allowing each stage to serve specific vacuum chambers at different pressure levels. This segmentation enables multi-chamber pressure control while keeping each individual stage relatively simple.
Solution Approach 2:
The rotor is designed as a multi-functional component that simultaneously performs pumping functions for multiple vacuum chambers at different pressure levels. The rotor disks with their pump-active surfaces can handle gas flow from multiple sources, making the rotor itself a universal element that serves multiple chambers, thereby reducing overall system complexity despite the multi-chamber configuration.
3Ease of manufacture
If standardized rotor disk assemblies with identical groups are used, then assembly is simplified and component variability is reduced, but the ability to optimize for different pressure levels in different chambers is limited
Solution Approach 1:
While the rotor disks are standardized in their basic structure and dimensions, the pump-active surfaces on each rotor disk are locally optimized for specific pressure ranges. The identical rotor disk groups can be configured with different surface patterns or geometries at specific locations to handle different pressure levels, thus maintaining assembly simplicity while achieving pressure level optimization through local variations.
Data Source
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AI summary
The present disclosure relates to a rotor for a turbomolecular pump with at least one turbomolecular pumping stage, comprising a rotatably mounted shaft having a bore arranged coaxially with an axis of rotation of the shaft, wherein the bore has an axial extent of more than 40%, in particular more than 45%, preferably more than 50% of an axial extent of the shaft, and which has a diameter in a section extending over more than 70%, in particular more than 80%, preferably more than 90% of the axial extent of the bore, exceeding 50%, in particular more than 65%, preferably more than 80% of the diameter of the shaft.