Conductive Seal Structure for High-Speed Motor Shaft Grounding
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Solution Overview
Problem
Conventional electrically conductive rubber seals fail to maintain effective electrical conductivity when used with rotary shafts rotating at high speeds, leading to issues like electromagnetic noise interference and electrolytic corrosion.
Innovation Solution
A sealing device with an electrically conductive elastic body unit that includes an annular member with an electrical continuity lip and a lubricant, forming a conductive circuit with an impedance range of 0.01 Ω to 100 Ω, even at high rotational speeds, using a reinforcing ring and elastic material with conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrically conductive rubber seals are used, then they can provide basic sealing and electrical conductivity, but they fail to maintain effective electrical conductivity at high rotational speeds
Solution Approach 1:
The patent changes the material parameters by using electrically conductive grease with specific conductivity properties (0.01 to 100 Ω) instead of conventional rubber materials. This parameter change allows the sealing device to maintain electrical conductivity at high rotational speeds where conventional materials fail.
Solution Approach 2:
The patent creates a composite structure combining electrically conductive grease with specific elastic body materials (fluorine rubber, vinyl rubber, or nitrile rubber). This composite approach leverages the electrical conductivity of the grease while utilizing the elastic properties of the rubber material to maintain contact under high-speed rotation.
2Reliability
If the sealing device maintains contact with the rotary shaft at high speeds, then electrical conductivity is preserved, but centrifugal force tends to separate the contact
Solution Approach 1:
The electrically conductive grease acts as an intermediary substance between the sealing device and the rotary shaft. This intermediary maintains electrical contact even when centrifugal force creates separation, as the grease can deform and fill gaps while maintaining conductive pathways.
Solution Approach 2:
The patent uses flexible elastic body materials (fluorine rubber, vinyl rubber, or nitrile rubber) that can deform under centrifugal force while maintaining contact with the rotary shaft. This flexibility allows the sealing device to adapt to high-speed rotation conditions while preserving electrical conductivity.
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
Maintains electrical conductivity and reduces electromagnetic noise interference and electrolytic corrosion by ensuring consistent contact with the rotary shaft, even at high speeds, through the use of a lubricant-filled conductive circuit.
Implementation Method 1
a lubricant with electrically conductive, the lubricant is interposed between the electrical continuity lip and the inner peripheral member
Implementation Method 2
an electrically conductive elastic body unit that is an annular member around an axis, the electrically conductive elastic body unit including a portion made of an elastic material with electrical conductivity
Data Source
AI summary
A sealing device capable of maintaining an electrically conductive performance relative to even an inner peripheral member rotating at a high speed. The sealing device includes an electrically conductive elastic body unit that is an annular member and that includes a portion made of an elastic material with electrical conductivity. The electrically conductive elastic body unit is able to come into contact with a shaft of an electric motor and a housing. The electrically conductive elastic body unit is able to form an electrically conductive circuit between the shaft of the electric motor and the housing. An impedance of the electrically conductive circuit during a rotation of the shaft of the electric motor at a circumferential velocity of 60 m/s or less is in a range from 0.01 Ω to 100 Ω.