Rotary Seal Gap Profile for Muddy Water Exclusion
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Solution Overview
Problem
Conventional rotary seals face challenges in maintaining wet-proof performance and sealing effectiveness, particularly when exposed to muddy water, as the centrifugal force causes muddy water to cling and scatter into the seal inner space, compromising the axial lip's sealing ability.
Innovation Solution
A rotary seal design featuring a radial gap with a first gap portion of fixed axial length and a second gap portion closer to the inward flange, where the second gap is conical and gradually increases in size, utilizing surface tension to hold muddy water and prevent it from entering the seal inner space, even under centrifugal force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a minute gap is provided radially outward from the axial lip to prevent muddy water penetration, then sealing function is improved, but muddy water clings to the gap end and scatters into the seal inner space due to centrifugal force, worsening wet-proof performance
Solution Approach 1:
The radial gap is segmented into two distinct portions: a first gap portion with constant width and a second gap portion with gradually increasing width. This segmentation allows the first portion to provide sealing function while the second portion prevents muddy water clinging and scattering, resolving the contradiction between sealing function and wet-proof performance.
Solution Approach 2:
Different portions of the radial gap are given different local characteristics: the first gap portion has constant width for sealing, while the second gap portion has gradually increasing width to prevent muddy water adhesion. This local differentiation allows each portion to optimize its specific function, improving both sealing and wet-proof performance simultaneously.
2Reliability
If the radial gap is extended to improve sealing, then sealing function is enhanced, but muddy water is present across the entire region and clings to the gap end, worsening wet-proof performance
Solution Approach 1:
The extended radial gap is divided into two functional zones: the first gap portion provides the extended sealing length, while the second gap portion with increasing width prevents muddy water adhesion. This segmentation resolves the contradiction by allowing extension without the harmful clinging effect.
Solution Approach 2:
The radial gap transitions from a two-dimensional constant width gap to a three-dimensional structure with varying width in the axial direction. The second gap portion's gradually increasing width creates a dimensional change that prevents muddy water from maintaining contact across the entire gap length, eliminating the scattering problem while preserving sealing function.
3Reliability
If a labyrinth structure is used to prevent muddy water penetration, then sealing function is improved, but device complexity increases
Solution Approach 1:
Instead of implementing a complex labyrinth structure throughout, the invention applies a simplified local quality approach by creating a radial gap with specific width variations. This local modification achieves sealing function without the complexity of multi-directional labyrinth passages, reducing device complexity while maintaining reliability.
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
Enhances wet-proof performance of the axial lip, inhibits the decrease in sealing performance, and maintains a simple structure without complex labyrinth designs, thereby reducing manufacturing costs and preventing muddy water from penetrating the bearing.
Implementation Method 1
utilizing surface tension to hold muddy water and prevent it from entering the seal inner space
Implementation Method 2
the centrifugal force causes muddy water to cling and scatter into the seal inner space
Data Source
AI summary
A radial gap between an outer circumferential surface of an encoder member joined to an outward flange portion of a slinger and an inner circumferential surface of a seal body includes a first gap portion and a second gap portion closer to an inward flange portion of a core metal than the first gap portion is. The outer circumferential surface that defines the first gap portion is a cylindrical outer circumferential surface, and the radial gap in the first gap portion is substantially constant in an axial direction. The outer circumferential surface that defines the second gap portion is a conical outer circumferential surface reduced in diameter as approaching the inward flange portion of the core metal in the axial direction, and the radial gap in the second gap portion is gradually increased as approaching the inward flange portion of the core metal in the axial direction.