Spring-Energized Seal EMI Shielding via Conductive Ring
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Solution Overview
Problem
Rotary lip-type seals made from soft materials face premature failure due to increased temperature from higher contact area under sealing stress, leading to reduced tensile and shear strength, while harder materials with higher modulus of elasticity compromise flexibility and sealing effectiveness.
Innovation Solution
A spring energized seal assembly with a conductive path defined by spring energizers and a conductive ring element provides EMI shielding, incorporating a biasing element and latching arms to maintain sealing effectiveness and flexibility, while the conductive path limits electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If soft elastomeric materials are used for rotary lip-type seals, then flexibility and adaptability to tolerance variations are improved, but temperature increase under high sealing stress reduces tensile and shear strength leading to premature failure
Solution Approach 1:
The seal assembly combines a soft seal element (elastomeric or PTFE material) with a hard conductive ring element (metal or conductive plastic), creating a composite structure that leverages the flexibility and sealing capability of the soft material while incorporating the thermal stability and structural integrity of the hard material to resist temperature-induced failure
Solution Approach 2:
The seal is divided into separate functional components: a soft seal element for sealing and a separate conductive ring element for EMI shielding and structural support, allowing each component to be optimized for its specific function without compromising the other
2Temperature
If harder materials with higher modulus of elasticity are used, then temperature resistance is improved, but flexibility and sealing effectiveness are compromised
Solution Approach 1:
The composite structure assigns the soft seal element to provide sealing effectiveness through its flexibility and compliance, while the hard conductive ring element provides temperature resistance and structural stability, allowing both requirements to be satisfied simultaneously
Solution Approach 2:
Different parts of the seal assembly have different material properties optimized for their specific functions: the seal element uses soft, compliant material for sealing contact, while the conductive ring element uses hard, thermally stable material for EMI shielding and structural support
3Adaptability or versatility
If higher sealing stress is applied to achieve good sealing with higher modulus materials, then sealing effectiveness is improved, but the range of tolerances under which they can function properly is limited
Solution Approach 1:
The soft seal element can deform to accommodate tolerance variations in the sealing surfaces, maintaining effective sealing without requiring high sealing stress, while the hard conductive ring element provides stable structural support
Solution Approach 2:
The seal element's low modulus of elasticity allows it to undergo elastic deformation within a wide range of sealing stresses, accommodating tolerance variations in the sealing surfaces and maintaining sealing effectiveness across different operating conditions
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 enhances seal life by maintaining flexibility and sealing efficiency while effectively shielding against electromagnetic interference, addressing the limitations of both soft and hard materials in rotary lip-type seals.
Implementation Method 1
a first spring groove having a first spring energizer located therein and biasing the inside flange and the outside flange away from one another
Implementation Method 2
a conductive path defined at least in part by a second spring energizer and a third spring energizer in electrical communication with one another for EMI shielding
Data Source
AI summary
Seal assemblies with a seal body having an inside flange and an outside flange that are biased outwardly away from one another by a spring energizer, such as a canted coil spring or a V-spring. The seal assemblies further include EMI shielding by incorporating at least one spring energizer that provides at least part of a conductive path between a housing and a pin. The conductive path can alternatively be provided by two different spring energizers and optionally with a conductive strip or trace or via a conductive contact ring element. The present seal assemblies are usable in applications having the needle for both sealing and EMI shielding.