Split Wire Harness Grommet With Self-Aligning Waterproof Seal
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Solution Overview
Problem
Conventional grommets with a two-split structure improve assembling workability by eliminating tube expanding work but face challenges in maintaining positional stability of joint surfaces due to distortion and require precise alignment, which complicates assembly and may lead to waterproofing issues.
Innovation Solution
A grommet design featuring a split structure with hard resin base members and a soft resin waterstop member, utilizing a holding mechanism to secure the assembly and a flexible piece to absorb forces, ensuring waterproofing without requiring precise alignment of joint surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a two-split structure is used to eliminate tube expanding work, then assembling workability is improved, but positional deviation of joint surfaces occurs due to member distortion
Solution Approach 1:
The grommet is divided into a first base member and a second base member that can be assembled separately. Each base member has a fitting portion that can be independently installed onto the peripheral edge of the through hole, eliminating the need for tube expanding work while maintaining assembly simplicity.
Solution Approach 2:
A waterstop member is introduced as an intermediary component between the first base member and the second base member. This waterstop member includes a positioning portion that fits into a positioning groove, serving as a mediator to ensure accurate alignment and prevent positional deviation of the joint surfaces during assembly.
2Ease of operation
If a two-split structure is used to improve assembling workability, then tube expanding work is eliminated, but assembly complexity increases due to the need for precise alignment
Solution Approach 1:
The waterstop member is designed with a positioning portion that automatically engages with the positioning groove when the first and second base members are assembled. This self-positioning mechanism eliminates the need for operators to perform complex alignment operations, allowing the components to self-align during the assembly process.
Solution Approach 2:
The waterstop member serves as a mediator that simplifies the assembly process by providing a built-in positioning mechanism. The positioning portion and positioning groove create a guided assembly path, reducing the complexity of aligning the joint surfaces without requiring additional alignment tools or procedures.
3Strength
If base members are made from hard resin for structural stability, then strength is improved, but waterproofness becomes difficult to ensure at joint surfaces
Solution Approach 1:
The grommet employs a composite structure where the base members are made from hard resin for structural strength, while the waterstop member is made from soft resin to ensure waterproofness. This combination of different material properties allows the hard resin base members to provide structural stability while the soft resin waterstop member fills gaps and ensures waterproof sealing at the joint surfaces.
Solution Approach 2:
Different parts of the grommet are assigned different material properties: the base members use hard resin for strength and structural support, while the waterstop member uses soft resin for flexibility and sealing. This local differentiation of material quality ensures that each component performs its specific function optimally - the hard resin provides structural integrity while the soft resin ensures waterproofness at the joint surfaces.
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 design enhances assembling workability by preventing positional deviation of joint surfaces and maintaining waterproof integrity, simplifying the installation process while effectively preventing liquid ingress.
Implementation Method 1
a waterstop member having an annular shape and formed of a soft resin softer than the hard resin and elastically deformable
Implementation Method 2
a flexible piece portion that is cantilever, and in which the projection is provided on a free end side and the projection is bent by a force received from an inner circumferential surface of the peripheral edge
Data Source
AI summary
A grommet includes: first and second base members, a waterstop member, and a holding mechanism. The first and second base members form: a flange that causes an outer peripheral edge to face the peripheral edge with a gap; a tubular body that protrudes from an inner peripheral edge of the flange and allows passage of a wiring member inside the body; and a cylindrical body that protrudes from the flange so as to be inserted through the through hole. Each of the first and second base members includes: a split flange, a split tube, and a split cylinder. The waterstop member includes: a fitting portion to be fitted into the outer peripheral edge of the flange; and a contact portion protruding from the fitting portion in the other hole axial direction so as to be, while being elastically deformed, in close contact with the peripheral edge over one circumference.