Vacuum Pump Spiral Plate Offset Design
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Solution Overview
Problem
The existing vacuum pump design with spiral plates experiences reduced exhaust efficiency due to gas flowing backward through gaps between the plates, leading to decreased productivity and efficiency.
Innovation Solution
The vacuum pump design incorporates spiral plates with slits where the downstream plate is offset to overlap the upstream plate, reducing the gap and using a machining end mill with a smaller radius than the slit width and phase difference, and chamfering acute angle portions to prevent backward gas flow and enhance machining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the angle of each spiral plate is small to maintain a continuous spiral shape from inlet to outlet, then machining in the manufacturing process becomes easy, but a gap is created between upstream and downstream spiral plates causing gas to flow backward and reducing exhaust efficiency
Solution Approach 1:
The patent applies asymmetry by offsetting the downstream spiral plate relative to the upstream spiral plate in the radial direction. This creates an asymmetric overlapping configuration where the spiral plates are not aligned on the same extended line, thereby eliminating the gap that causes gas backward flow while maintaining manufacturability through controlled asymmetric positioning.
Solution Approach 2:
The patent introduces a radial offset dimension between upstream and downstream spiral plates. Instead of maintaining simple axial alignment, the downstream plate is positioned at a different radial distance from the rotation axis, creating an overlapping relationship in the radial dimension that prevents gap formation without compromising the continuous spiral geometry.
2Device complexity
If spiral plates are positioned with a small angle to maintain continuous spiral shape, then the spiral structure is simple to manufacture, but gas flows backward through the gap between plates reducing vacuum pump performance
Solution Approach 1:
The asymmetric radial positioning of spiral plates resolves the contradiction by creating a deliberate offset between upstream and downstream plates. This asymmetric configuration eliminates the gap that causes gas backward flow (improving reliability) while maintaining a relatively simple continuous spiral structure (controlling device complexity).
Solution Approach 2:
The overlapping region between upstream and downstream spiral plates acts as an intermediary structure that prevents gas backward flow. This overlapping configuration serves as a mediator that maintains both the continuous spiral shape for structural simplicity and the gap-free configuration for performance reliability.
3Ease of manufacture
If the spiral plates are aligned on the same extended line, then machining is easier with continuous spiral shape, but gas flows backward through the gap reducing exhaust efficiency
Solution Approach 1:
The patent eliminates gas backward flow loss by introducing asymmetric radial positioning of spiral plates. The downstream plate is offset from the upstream plate's extended line, creating an overlapping configuration that blocks the backward flow path while maintaining machining feasibility through controlled asymmetric geometry.
Solution Approach 2:
The patent converts the potential harm of gas backward flow into a benefit by creating an overlapping configuration. The offset positioning that might seem to complicate the structure actually prevents energy loss by blocking the backward flow path, turning a potential structural complexity into an energy-saving feature.
Data Source
AI summary
In a vacuum pump, a spiral plate on a downstream side of a slit is not disposed on an extended line of a spiral plate on an upstream side of the slit but is disposed after in a direction in which a gap formed by the slit is reduced. The distance by which the downstream spiral plate is moved corresponds to the distance in which the gap disappears and the upstream spiral plate and the downstream spiral plate overlap. When scraping the spiral plates, the radius of a machining end mill is set smaller than the width of the slit of the spiral plate, and the radius of the machining end mill is set smaller than the phase difference between the upstream spiral plate and the downstream spiral plate. In addition, end portions of the spiral plates between which the slit is formed are subjected to chamfering.