Metal Bellows End Geometry for Stress-Resistant Ring Mounting
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Solution Overview
Problem
Conventional metal bellows designs experience breakage at the end portions due to constant pitch, which causes stress concentration and limits the axial width of vibration damping rings, leading to potential breakage when fitted in devices like accumulators.
Innovation Solution
A metal bellows assembly with an annular shape featuring a unique structure of belly, valley, and peak formations at the end portions, where the connection valley has a larger axial width and a linear portion parallel to the axial direction, reducing deformation and stress, and providing space for secure vibration damping ring mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the pitch is constant over the entire length of the metal bellows, then the structure is simple and easy to manufacture, but great stress acts on the end portions connected to collar members, causing breakage
Solution Approach 1:
The patent applies local quality by making the pitch variable rather than constant. Specifically, the pitch between adjacent valleys is set to be different from the pitch between adjacent peaks, creating local structural differences. This allows the end portions to have enhanced stress resistance through modified geometry while maintaining simplicity in the overall manufacturing process. The connection valleys at end portions are designed with specific dimensional relationships (e.g., width ratios between 0.8-1.2) to locally optimize stress distribution without complicating the entire bellows structure.
2Shape
If the pitch is constant over the entire length of the metal bellows, then the structure is uniform, but the axial width of the valley portion is limited, restricting the size of vibration damping rings that can be fitted
Solution Approach 1:
The patent implements local quality by creating non-uniform pitch distribution along the bellows length. The pitch between valleys is designed to differ from the pitch between peaks, with specific ratios (0.8-1.2) to optimize both structural integrity and component accommodation. This local variation allows the valley portions to have sufficient axial width for fitting vibration damping rings of appropriate sizes while maintaining overall structural coherence and manufacturing simplicity.
3Device complexity
If the pitch is constant over the entire length, then the structure is simple, but when the gap between the vibration damping ring and bellies is small, the vibration damping ring abuts the bellies, breaking them
Solution Approach 1:
The patent applies local quality by designing different pitch values for different sections of the bellows. The pitch between valleys is specifically optimized to be different from the pitch between peaks, creating adequate clearance spaces at critical locations. This local optimization ensures that vibration damping rings have sufficient gap from adjacent bellies during operation, preventing harmful contact and stress concentration that would occur with uniform pitch design.
Solution Approach 2:
The patent employs beforehand cushioning by pre-designing the pitch dimensions to ensure adequate clearance between vibration damping rings and bellies before any harmful contact can occur. The pitch between valleys is calculated and set to provide sufficient space for the vibration damping rings, preventing potential breakage from the outset rather than addressing the problem after it arises.
Data Source
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AI summary
A metal bellows of great durability capable of preventing breakage at both end portions of the metal bellows is provided. The metal bellows is annular-shaped and has, axially repeatedly, a structure in which, from an axial end portion 10c, a belly, a valley, a belly, a peak, and a belly are integrally formed in series sequentially in this order. The end portion 10c has a first connection belly 10d connected to a fitting member 15, and a connection valley 10e and a second connection belly 10f extending sequentially from the first connection belly 10d axially inward. The axial width b1 of the connection valley 10e in a free state is set larger than the axial width of valleys 10i, 10m, ... or peaks 10g, 10k, ... in a portion other than the end portion 10c.