Vacuum Pump Rotating Cylinder Outer Layer Thickness
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Solution Overview
Problem
The use of fiber-reinforced resin (FRP) rotating cylinders in vacuum pumps faces challenges due to surface irregularities and internal stress nonuniformity caused by fiber overlapping, positional misalignment, and machining processes, leading to deformation and an inability to sufficiently reduce the gap between the rotating and fixed cylinders, which hampers exhaust performance.
Innovation Solution
The solution involves configuring the outermost fiber-reinforced resin layer to be at least 25% thicker than adjacent layers, with a hoop layer as the outermost layer and ensuring the innermost layer is also a hoop layer, and setting other layers to be equal in thickness, to minimize internal stress and deformation caused by machining and fiber cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the outermost layer is made thin and the number of layers is increased to average material characteristics, then the material characteristics are averaged, but surface irregularities form due to fiber overlapping and positional misalignment
Solution Approach 1:
The patent applies local quality by making the outermost layer thicker than the intermediate layers. This localized thickness variation compensates for surface irregularities caused by fiber overlapping and positional misalignment in the thinner intermediate layers, while still maintaining the averaging effect of multiple layers on material characteristics.
2Manufacturing precision
If removal machining is performed on surface irregularities, then the surface shape precision is improved, but internal stress nonuniformity occurs due to release of internal strain causing the rotating cylinder to flex
Solution Approach 1:
The patent applies local quality by concentrating the thickness increase in the outermost layer, which localizes the material distribution to compensate for stress changes. This thicker outer layer provides a buffer that reduces the impact of stress release during machining, preventing excessive flexing while still allowing surface precision to be achieved.
3Productivity
If the gap between the rotating cylinder and fixed cylinder is reduced to improve exhaust performance, then the exhaust performance is improved, but the rotating cylinder deforms due to internal stress and material flexing
Solution Approach 1:
The patent applies local quality by making the outermost layer thicker, which provides localized structural reinforcement at the critical outer surface. This allows the overall cylinder to maintain its shape and resist deformation even when the gap to the fixed cylinder is reduced for improved exhaust performance.
4Weight of moving object
If the rotating cylinder is made of FRP to reduce weight, then the weight is reduced, but the rotating cylinder deforms due to anisotropic material characteristics and internal strain
Solution Approach 1:
The patent applies local quality by varying the thickness of the outermost layer compared to intermediate layers. This non-uniform thickness distribution compensates for the anisotropic nature of FRP materials, providing enhanced structural stability in critical areas while maintaining the overall weight advantages of using FRP instead of metal.
Solution Approach 2:
The patent uses fiber-reinforced resin (FRP) as a composite material to construct the rotating cylinder, combining fibers and resin to achieve a lightweight structure with high strength. This composite material approach allows for weight reduction while maintaining structural integrity through proper layer configuration.
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
Provided is a vacuum pump in which the flexing of a rotating cylinder made of a fiber-reinforced resin can be reduced as much as possible to sufficiently reduce the gap between the rotating cylinder and a fixed cylinder, and exhaust performance can thereby be improved to great effect. A vacuum pump comprising a thread groove pump portion equipped with a fixed cylinder portion (2) having a spiraling thread groove portion (1) provided in an internal peripheral surface, and a rotating cylinder portion (3) placed inside the fixed cylinder portion (2), the thread groove pump portion exhausting through a spiraling exhaust flow channel due to the rotating cylinder portion (3) being caused to rotate, and the exhaust flow channel being formed from the thread groove portion (1) and an external peripheral surface of the rotating cylinder portion (3). The rotating cylinder portion (3) is configured by stacking a plurality of fiber-reinforced resin layers, and the outermost fiber-reinforced resin layer is thicker than the adjacent layer.