Conductive Rubber Sealing Device for Electromagnetic Noise Control
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Solution Overview
Problem
Existing sealing devices for vehicle power transmission devices face issues such as the need for additional components like conductive brushes, separation due to eccentricity or wear, and high sliding friction, which affect noise suppression and sealing performance.
Innovation Solution
A sealing device with a reinforcement ring, elastic portion, and conductive grease that forms a continuous path between the output shaft and casing, reducing sliding friction and noise generation by using a conductive rubber with a garter spring to maintain contact and a conductive grease to ensure electrical continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a conductive brush is separately added to establish continuity between case and drive shaft, then electromagnetic noise suppression is improved, but device complexity increases and installation space requirements increase
Solution Approach 1:
The patent combines the sealing function and electromagnetic continuity function into a single oil seal component. The oil seal body made of conductive rubber provides both sealing against oil leakage and electrical continuity for noise suppression, eliminating the need for separate conductive brush components and simplifying the overall device structure.
Solution Approach 2:
The oil seal is designed to perform multiple functions simultaneously: it seals the void between the through-hole and rotating shaft to prevent oil leakage, while also establishing electrical continuity through its conductive rubber material to suppress electromagnetic noise from leakage currents.
2Object-generated harmful factors
If an oil seal made of conductive rubber is used to establish electrical continuity, then electromagnetic noise suppression is improved, but reliability decreases due to separation from eccentricity or wear
Solution Approach 1:
The patent incorporates a garter spring within the oil seal structure that provides continuous radial force to press the sealing lip against the rotating shaft. This dynamic mechanism compensates for shaft eccentricity and maintains reliable electrical contact between the conductive oil seal and the shaft throughout operation, preventing separation due to wear or misalignment.
Solution Approach 2:
The garter spring creates a feedback mechanism where the spring force automatically adjusts to maintain contact pressure between the oil seal and rotating shaft. As the shaft rotates and experiences wear or eccentricity, the spring continuously applies radial force to keep the conductive surfaces in contact, ensuring sustained electrical continuity.
3Object-generated harmful factors
If three conductive lip portions contact the hub ring to suppress radio noise, then electromagnetic noise suppression is improved, but sliding friction increases
Solution Approach 1:
The patent merges the sealing lip and electrical contact function into a single integrated structure. The oil seal uses one sealing lip that simultaneously provides mechanical sealing and electrical continuity through the conductive rubber material, eliminating the need for multiple separate conductive lip portions and reducing total sliding friction.
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 sealing device improves sealing performance, reduces sliding friction, and effectively suppresses noise generation by maintaining contact and continuity between the shaft and casing, even with eccentricity or wear, without additional components.
Implementation Method 1
an elastic portion (30) which is attached to the reinforcement ring (20) and made of a conductive rubber
Implementation Method 2
a garter spring (38) which is placed in the recessed part
Implementation Method 3
the conductive grease (G) which is adherent to the inner peripheral surface (83) of the elastic portion (30)
Data Source
Figure 1
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Figure 3
AI summary
Generation of noise is suppressed while original sealing performance is maintained. A sealing device (10) has a reinforcement ring (20) in an annular shape around an axis (x), an elastic portion (30) which is attached to the reinforcement ring (20) and is an elastic body in an annular shape around the axis (x) and having conductivity, and conductive grease (G). The elastic portion (30) has a base (31), a lip portion (35) which extends from the base (31) along the axis (x), and at least one dust lip (85) in an annular shape around the axis (x). The lip portion (35) has, at a tip end, a lip tip end portion (36) having a lip contact surface (36s) which is formed to be capable of contacting an outer peripheral surface of a shaft such that the outer peripheral surface of the shaft is slidable. The lip contact surface (36s) has a surface in an annular shape which faces the outer peripheral surface of the shaft. The conductive grease (G) is adherent in at least a part of an inter-lip space which is a space in an annular shape formed between the lip contact surface (36s) and the dust lip (85) in a direction of the axis (x).