Mechanical Seal Bellows Fitting to Prevent Long-Term Slipping
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Solution Overview
Problem
Conventional mechanical seals with bellows seals experience reduced sealing efficiency over time due to the slipping of the bellows seal on a smooth inner circumferential surface, leading to compromised long-term sealing performance.
Innovation Solution
Incorporating a slipping stopper on the inner circumferential surface of the case's fitting part to prevent relative rotation of the elastic seal, using features like knurling, shot blasting, or recesses to enhance surface roughness and prevent slipping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the inner circumferential surface of the fitting part is made smooth and slippery, then the bellows seal can be easily fitted and fixed to the case, but the bellows seal may slip on the surface over time, lowering sealing efficiency
Solution Approach 1:
The patent applies local quality by creating a slipping stopper with increased surface roughness at a specific location on the inner circumferential surface of the fitting part. This localized roughness feature prevents the bellows seal from slipping while maintaining ease of fitting in other areas. The slipping stopper is formed by machining grooves or protrusions that create local friction without requiring the entire surface to be rough.
Solution Approach 2:
The patent implements partial action by providing the slipping stopper only at the necessary location on the fitting part where the bellows seal makes contact. The slipping stopper is not applied to the entire inner circumferential surface but only at the specific region needed to prevent slipping, thus avoiding excessive roughness that would complicate manufacturing while still achieving the anti-slip function.
2Device complexity
If the bellows seal is fixed to the case by fitting on a smooth inner circumferential surface, then the structure can be simplified, but the sealing performance deteriorates over time due to slipping
Solution Approach 1:
The slipping stopper introduces local surface roughness at a specific position on the fitting part without changing the overall simple fitting structure. This localized modification prevents slipping while maintaining the simplicity of the fitting process and structure. The rest of the inner circumferential surface remains smooth for easy fitting.
Solution Approach 2:
The patent changes the surface roughness parameter locally at the slipping stopper position. By increasing the roughness parameter (Ra value) only at this specific location through machining grooves or protrusions, the patent prevents slipping while keeping the overall structure simple and the fitting process straightforward.
3Reliability
If the inner circumferential surface is made rough to prevent slipping, then sealing efficiency is maintained, but manufacturing complexity and cost increase
Solution Approach 1:
The slipping stopper applies surface roughness only at the necessary location where the bellows seal contacts the fitting part, rather than making the entire inner circumferential surface rough. This localized approach maintains sealing efficiency while minimizing manufacturing complexity and cost.
Solution Approach 2:
The patent uses partial action by creating the slipping stopper only at the specific region needed to prevent slipping. The machining operations (grooves or protrusions) are applied only to the portion of the inner circumferential surface that contacts the bellows seal, avoiding unnecessary manufacturing complexity in other areas.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design stabilizes sealing performance over a long period by preventing the bellows seal from sliding, thus maintaining efficient sealing and reducing manufacturing complexity and costs.
Implementation Method 1
using features like knurling, shot blasting, or recesses to enhance surface roughness and prevent slipping
Data Source
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AI summary
A mechanical seal which can provide stable sealing performance over a long period of time. A rotating ring unit 100 includes an annular elastic seal 130 having a first annular part 131 to which a rotating ring 110 is fitted and thus fixed on an inner circumferential surface side thereof, a second annular part 133 provided in close contact with an outer circumferential surface of a rotating shaft, and a curved part 132 which connects the first and second annular parts 131 and 133 and follows a positional change of the second annular part 133 with respect to the first annular part 131, an annular tightening member 140 which tightens an outer circumferential surface of the second annular part 133 on the rotating shaft, and a metal case 120 including an annular fitting part 121 to which the first annular part 131 is fitted and thus fixed on the inner circumferential surface side thereof. The fitting part includes a slipping stopper formed on an inner circumferential surface thereof, the slipping stopper being configured to restrain the first annular part 131 from relatively rotating in the circumferential direction.