Double-Seal Waterproof Wire Housing for Thermal Expansion
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Solution Overview
Problem
The existing waterproof structures for connectors face issues such as appearance defects, wire breakage, and a decrease in waterproof function due to differences in linear expansion coefficients between the insulation, elastomer, and housing materials, leading to protrusion, wrinkles, and deformation.
Innovation Solution
A waterproof structure is designed with a first seal portion made of an elastic material, primarily molded on the electric wire insulation, and a second seal portion also made of an elastic material, contiguously molded with one end portion of the housing. This configuration embeds the first seal portion within the housing and provides a contiguous second seal portion to cover the electric wire, ensuring a double waterproof structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single elastomer seal portion is used to ensure waterproof function, then waterproof reliability is improved, but thermal expansion differences cause protrusion and deformation leading to appearance defects and wire breakage
Solution Approach 1:
The single elastomer seal portion is divided into two separate seal portions: a first seal portion that contacts the insulation and a second seal portion that contacts the housing. This segmentation allows each seal portion to independently accommodate thermal expansion without causing deformation to the insulation or protrusion from the housing.
Solution Approach 2:
The first seal portion acts as an intermediary between the insulation and the second seal portion, which in turn intermediates between the elastomer material and the housing. This intermediary structure absorbs thermal expansion forces before they reach the insulation, preventing deformation and wire breakage.
2Shape
If the elastomer seal portion is embedded in the housing, then appearance defects are reduced, but thermal expansion causes the elastomer to be pushed out of the housing
Solution Approach 1:
The seal structure is segmented into two portions with different embedding configurations. The first seal portion is embedded in the housing to maintain appearance quality, while the second seal portion extends beyond the housing to accommodate thermal expansion, preventing the seal material from being pushed out.
Solution Approach 2:
Different portions of the seal structure have different qualities: the first seal portion has a embedded configuration for appearance, while the second seal portion has an extended configuration for thermal accommodation. This local differentiation allows each portion to serve its specific function optimally.
3Stability of the object's composition
If the second seal portion extends beyond the housing, then thermal expansion accommodation is improved, but waterproof function decreases due to exposure
Solution Approach 1:
The seal is segmented into two portions with distinct functions: the first seal portion remains embedded to maintain waterproofing, while the second seal portion extends beyond the housing to accommodate thermal expansion. This segmentation allows both waterproof function and thermal accommodation to be achieved simultaneously.
Solution Approach 2:
The two seal portions work together as a unified waterproof system. The first seal portion provides the primary waterproof barrier when embedded, while the second seal portion complements it by accommodating thermal expansion, together maintaining both waterproof function and thermal stability.
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 proposed solution prevents the protrusion of the first seal portion and reduces deformation of the insulation, thereby eliminating appearance defects and maintaining the waterproof function even under thermal expansion and contraction.
Implementation Method 1
an insulating elastic member is primarily molded as a first seal portion (25) and an insulating resin is secondarily molded as a housing (13) on the first seal portion (25) and on a part of the terminal (19)
Implementation Method 2
due to a difference in linear expansion coefficient of the insulation, the elastomer and the housing material, a part of the elastomer that is overlapped by the housing may be pushed out of the housing
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A waterproof structure includes a first seal portion covering around an electric wire to be inserted into a mounting hole of an object to which the electric wire is mounted, the electric wire having a conductor and an insulation covering the conductor, and the first seal portion being elastic and electrically insulative, a housing provided at an end portion of the electric wire, the housing covering the first seal portion, the housing being made of an insulating resin having higher rigidity than the first seal portion and a second seal portion covering around an electric wire being provided contiguously with an end portion of the housing and being elastic and electrically insulative.