Mechanical Seal Structure to Prevent Bellows Seal Slipping
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Solution Overview
Problem
Conventional mechanical seals with bellows seals experience reduced sealing efficiency over time due to the bellows seal slipping on the smooth inner circumferential surface of the case, leading to instability in sealing performance.
Innovation Solution
A mechanical seal design featuring a rotating ring unit with an annular elastic seal and a metal case with a slipping stopper on the inner circumferential surface of the fitting part, which prevents relative rotation and maintains sealing efficiency by using a knurled, shot blasted, or textured surface to restrain the elastic seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the inner circumferential surface of the fitting part is made smooth, then the bellows seal can be easily fitted and fixed, but the bellows seal may slip on the surface over time, reducing sealing efficiency
Solution Approach 1:
The inner circumferential surface of the fitting part is designed with different surface qualities at different locations: the first circumferential direction (axial direction) maintains a smooth surface for easy fitting, while the second circumferential direction (rotational direction) incorporates a slipping stopper with increased roughness to prevent rotational slipping. This local differentiation resolves the contradiction between ease of fitting and prevention of slipping.
2Device complexity
If the bellows seal is allowed to rotate freely on the fitting part, then the structure remains simple, but the sealing performance deteriorates over time due to slipping
Solution Approach 1:
Instead of making the entire inner circumferential surface rough or adding complex restraining structures, the invention applies a slipping stopper only in the circumferential direction where slipping occurs. The axial direction remains smooth for easy fitting. This localized approach prevents slipping while maintaining overall structural simplicity.
3Reliability
If a slipping stopper is added to the fitting part, then the bellows seal is restrained from rotating, but the structure becomes more complex
Solution Approach 1:
The slipping stopper is integrated into the existing fitting part structure rather than being a separate component. It is formed by locally increasing the roughness of the inner circumferential surface in the circumferential direction, while maintaining smoothness in the axial direction. This integration minimizes structural complexity while achieving the reliability improvement.
Solution Approach 2:
The invention changes the surface roughness parameter of the fitting part's inner circumferential surface. By increasing the roughness specifically in the circumferential direction (creating the slipping stopper), the friction between the bellows seal and the fitting part is increased, preventing slipping. This parameter change achieves the anti-slip function without adding structural complexity.
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
The mechanical seal maintains stable sealing performance over a long period by preventing the elastic seal from slipping, thus ensuring consistent fluid containment.
Implementation Method 1
a slipping stopper formed on an inner circumferential surface of the fitting part, the slipping stopper being configured to restrain the first annular part from rotating relatively in the circumferential direction
Data Source
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.