Conductive Buffer Seal Layout for Electrostatic Shaft Protection

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Solution Overview

Problem

Existing radial shaft seal assemblies fail to effectively prevent electrostatic charges from causing mechanical damage and electromagnetic interference between machine elements, as they do not provide adequate electrical conductivity to equalize potential.

Innovation Solution

A sealing assembly featuring a primary radial shaft seal, a conductive nonwoven fiber buffer seal made from copper-nickel impregnated carbon fibers, and a secondary contaminant exclusion seal, where the buffer seal is sandwiched between the primary seal and the secondary seal, allowing for electrical conductivity and potential equalization between machine elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional radial shaft seal assembly is used, then sealing function is provided, but electrostatic charges cause mechanical damage and electromagnetic interference between machine elements

Engineering Contradiction:

Improveprevention of mechanical damage and electromagnetic interferenceVSAvoidelectrostatic charge

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a buffer seal made of electrically conductive nonwoven fabric as an intermediary component between the primary radial shaft seal and the secondary contaminant exclusion seal. This buffer seal acts as a mediator to conduct away electrostatic charges, preventing them from causing mechanical damage or electromagnetic interference to the machine elements (shaft and housing). The conductive material in the buffer seal provides a controlled path for charge dissipation, thereby protecting the sealed components.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 conductive nonwoven fiber buffer seal equalizes electric potential between machine elements, preventing mechanical damage and electromagnetic interference by grounding one element, thereby reducing the risk of electrostatic charges causing harm.

Implementation Method 1

a buffer seal made of an electrically conductive non-woven fabric... the machine elements that are to be sealed off from one another by the sealing assembly are connected to one another in electrically conductive fashion owing to the electrical conductivity of the buffer seal

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP3835628B1Contamination exclusion for seal ring with conductive nonwoven fiber

Publication Date: 2023.05.17 FREUDENBERG NOK GEN PARTNERSHIP

Figure 1

AI summary

A sealing assembly including a housing including a bore and a shaft rotatably disposed in the bore. A primary radial shaft seal is secured to the housing and includes a sealing lip engaging the shaft. A buffer seal made of an electrically conductive non-woven fabric which is arranged adjacent to the primary radial shaft seal and in contact with the housing and the shaft. A secondary contaminant exclusion seal is secured to the housing and includes at least one dust lip. The buffer seal is sandwiched between the primary radial shaft seal and the secondary contaminant exclusion seal.