Vacuum Pump Stationary Blade Rim Floating Design
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Solution Overview
Problem
In vacuum pumps, the displacement of the inner circumferential rim of stationary blade portions with respect to the outer circumferential rim during manufacturing can lead to contact with rotating blade portions, causing operational risks due to variations in the working process.
Innovation Solution
The stationary blade portions are designed with a blade height on the inner circumferential side being smaller than on the outer circumferential side, and the inner circumferential rim is floated up towards the intake port side by bending the outer circumferential edge of the rim, ensuring that the inner rim is displaced to a position where it avoids contact with rotating blade portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the stationary blade portions are manufactured by plastic working with pressing a plate, then the manufacturing cost is reduced, but the inner circumferential rim is displaced in the axial direction causing contact risk with rotating blade portions
Solution Approach 1:
The patent applies preliminary action by pre-forming the stationary blade portions with a specific blade height configuration (smaller inner circumferential blade height than outer circumferential blade height) before assembly. This pre-formed geometry ensures that when the inner circumferential rim is displaced axially during operation, the blade structure itself provides a mechanical stop that prevents contact with rotating blade portions, thereby eliminating the reliability issue while maintaining cost-effective plastic working manufacturing
Solution Approach 2:
The patent applies local quality by creating non-uniform blade height across the radial direction of the stationary blade portions. Specifically, the blade height is made smaller at the inner circumferential side and larger at the outer circumferential side. This local variation in geometry provides differential clearance that prevents contact between stationary and rotating blade portions while maintaining manufacturing simplicity through plastic working
2Reliability
If the blade height on the inner circumferential side is made smaller than on the outer circumferential side, then contact between blade portions is prevented, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by utilizing the inherent material properties and deformation characteristics of plastic working processes. By controlling the pressing parameters (force distribution, temperature, time) during plastic working, the desired blade height variation (smaller inner circumferential height than outer circumferential height) is achieved. This approach transforms the manufacturing challenge into an opportunity to leverage material behavior, achieving both contact prevention and acceptable manufacturing precision through controlled plastic deformation
Data Source
AI summary
A vacuum pump comprises an exhaust portion having a plurality of rotating blade portions arranged in multiple stages, each of the rotating blade portions having a plurality of rotor blades, and a plurality of stationary blade portions arranged between the rotating blade portions, in which outer circumferential rims are supported via spacers, each of the stationary blade portions having a plurality of stator blades. In at least one stationary blade portion among the plurality of stationary blade portions, a blade height on the inner circumferential side of the plurality of stator blades provided in the stationary blade portion is set to be smaller than a blade height on the outer circumferential side, and the stationary blade portion is supported by the spacers in such a manner that the inner circumferential side of the stationary blade portion is floated up toward an intake port side.