Aperture Seal Structure for Wire Harness Moisture Protection
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Solution Overview
Problem
Existing seal methods for electronic assemblies in harsh environments, such as outdoor light assemblies, are inefficient and prone to moisture intrusion due to the inability of prior art methods like rubber grommets and epoxy encapsulants to form a strong, self-healing seal around wires as they shift during installation or use.
Innovation Solution
A seal structure comprising a container filled with a liquid sealant that cures to a viscous gel, combined with a cap that applies positive pressure, creating a self-healing environmental seal around wires passing through the assembly housing, effectively preventing moisture and air intrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rubber grommets are used to seal wires passing through housing, then wires are protected from moisture, but the sealing process is slow and difficult to automate
Solution Approach 1:
The patent replaces the manual mechanical process of installing rubber grommets with an automated liquid sealant system. The liquid sealant is applied through dispensing equipment that automatically fills cavities and seals around wires, eliminating the need for manual grommet installation while maintaining moisture protection.
Solution Approach 2:
The patent changes the physical state of the sealing material from solid (rubber grommet) to liquid (sealant). The liquid sealant can flow into complex geometries and around wires, then cures to form a solid seal. This parameter change enables automated application while maintaining effective sealing.
2Reliability
If epoxy encapsulant is used to seal wires, then wires are protected from moisture, but the bond strength with wire jacket is insufficient
Solution Approach 1:
The patent uses a two-component sealant system consisting of a base polymer and a reactive crosslinking agent. These components react together to form a cured sealant with enhanced adhesive properties. The composite nature of the cured material provides both moisture protection and strong bonding to wire jackets.
Solution Approach 2:
The patent changes the chemical composition and physical properties of the sealant through a curing process. The liquid sealant transforms into a cured sealant with different mechanical properties including higher bond strength. This parameter change occurs after application, allowing the sealant to first flow into position then develop strong adhesive bonds.
3Reliability
If hardened epoxy is used to seal wires, then wires are protected from moisture, but the seal cannot accommodate wire movement
Solution Approach 1:
The patent creates a sealant system that transitions from a dynamic liquid state during application to a semi-rigid cured state that retains some flexibility. The cured sealant can deform and flow in response to wire movement while maintaining its sealing function, accommodating thermal expansion and contraction without compromising the moisture barrier.
Solution Approach 2:
The patent designs the sealant cavity with sufficient volume to accommodate future wire movement. The liquid sealant is applied in excess to ensure complete filling, and the cured sealant acts as a cushion that can deform to absorb dimensional changes from wire movement while maintaining the seal.
4Ease of manufacture
If traditional sealing methods are used, then assembly is simple, but moisture can pass through inside jacketed wires
Solution Approach 1:
The patent replaces mechanical sealing methods (grommets, crimps) with a chemical sealing approach using liquid sealant. The sealant is applied by automated dispensing equipment that fills cavities and creates seals along the wire path, providing more reliable moisture protection while remaining compatible with automated manufacturing processes.
Solution Approach 2:
The patent uses liquid sealant as an intermediary material that fills the space between the wire jacket and the housing cavity walls. This intermediary substance creates a continuous moisture barrier that bridges gaps and seals along the entire wire penetration path, preventing moisture ingress that traditional point-sealing methods cannot address.
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 a reliable, self-healing seal that maintains integrity even as wires shift, effectively preventing moisture and air from entering the enclosure, thus enhancing the durability and reliability of electronic assemblies in harsh conditions.
Implementation Method 1
A PC board may span the opening and an inner end of the container to form a closure defining the inner end of the chamber. The chamber and the opening are partially filled with a predetermined quantity of sealant in liquid form, which is allowed to cure into a viscous gel.
Implementation Method 2
The cap is configured to engage with the container and includes a platform that is positioned within the container and in contact with the gel sealant. In this arrangement, the cap applies positive pressure to the gel sealant.
Implementation Method 3
Under pressure, the gel sealant forms a tight environmental seal that 'self-heals' if conductors shift within the container and opening.
Data Source
AI summary
A seal structure includes a container, a sealant applied in liquid form that cures to a gel, and a cap that applies pressure to the gel. The container surrounds at least one opening in an assembly for the passage of elongated members such as wires. The container defines a chamber that is in communication with the opening and surrounds the wires passing through the opening. A closure spans the opening and is in contact with an inner end of the container. The chamber and the at least opening are partially filled with a predetermined quantity of sealant in liquid form, which cures into a viscous gel. The cap is configured to engage with the container and includes a platform that is positioned within the container and in contact with the gel sealant. In this arrangement, the cap applies positive pressure to the gel sealant.