Conductive Shaft Seal Structure for EMI Control and Lubricant Sealing
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Solution Overview
Problem
Existing sealing devices for electric vehicles and hybrid electric vehicles face challenges in ensuring reliable conduction between rotating shafts and housings while preventing electromagnetic noise and maintaining effective sealing, often requiring costly and space-intensive solutions.
Innovation Solution
A sealing device is designed with an annular sleeve tube part fixed to the rotating shaft, a ring-shaped conduction part that contacts the housing, and a sealing part with elastic components, which utilizes centrifugal force to ensure stable conduction and sealing, incorporating conductive materials to manage electromagnetic noise effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional non-conductive sealing device is used, then sealing performance is maintained, but electromagnetic noise cannot be conducted away from the rotating shaft
Solution Approach 1:
The sealing device is divided into multiple functional segments: a sealing element for lubricant containment, a conductive element for electromagnetic noise conduction, and a reinforcing ring for structural support. This segmentation allows each component to specialize in its function, with the conductive element specifically addressing electromagnetic noise while the sealing element maintains sealing performance.
Solution Approach 2:
The sealing device employs composite construction by combining materials with different properties - the sealing element uses elastomeric materials for flexibility and sealing, while the conductive element uses conductive rubber or fabric with embedded conductive particles to provide both sealing and electromagnetic noise conduction capabilities simultaneously.
2Object-affected harmful factors
If a conductive sealing device is used to conduct electromagnetic noise, then noise management improves, but contact reliability between the sealing device and metal surfaces deteriorates over time
Solution Approach 1:
The conductive element is designed with inherent elasticity and compliance to compensate for surface irregularities and dimensional changes. This pre-built cushioning capability ensures continuous contact between the conductive element and both the rotating shaft and housing, maintaining conduction reliability even as components wear or expand/contract during operation.
Solution Approach 2:
The conductive element's physical parameters such as hardness, elasticity, and cross-sectional area are optimized to maintain contact pressure within a specific range. This parameter control ensures reliable electrical contact for electromagnetic noise conduction while accommodating thermal expansion, wear, and manufacturing tolerances of the metal components.
3Object-affected harmful factors
If multiple separate components are used for sealing and conduction, then functional performance is achieved, but device complexity and space requirements increase
Solution Approach 1:
The sealing element and conductive element are merged into a single integrated sealing device assembly that performs both sealing and electromagnetic noise conduction functions. This merging eliminates the need for separate sealing components and conductive components, reducing overall device complexity and space requirements while maintaining both functional performances.
Solution Approach 2:
The sealing device is designed as a multi-functional component that simultaneously provides sealing against lubricant leakage and conduction path for electromagnetic noise. The conductive element serves dual purposes: maintaining contact for sealing integrity and providing the conduction path for electromagnetic interference management, thereby reducing the total number of components required.
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 solution provides reliable conduction and sealing between rotating shafts and housings at a low cost in a space-saving manner, effectively managing electromagnetic noise and maintaining lubricant containment for an extended period.
Implementation Method 1
rotation of the rotating shaft causes the sealing device to be pressed against the inner surface constituting the shaft hole in the housing
Implementation Method 2
the sealing device is capable of conduction between the rotating shaft and the housing
Data Source
AI summary
The present invention addresses the problem of providing a sealing device capable of achieving long-term electrical conductivity between a rotary shaft and a housing at low cost and in a space-saving manner. The problem is solved by a sealing device that is disposed in and seals a gap between an outer surface of a rotary shaft and an inner surface of a housing having a shaft hole into which the rotary shaft is inserted, the inner surface forming the shaft hole, and that can provide electrical conductivity between the housing and the rotary shaft pressed against the inner surface of the housing forming the shaft hole when the rotary shaft rotates.