Grommet Covering Portion Deformation for Insertion
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Solution Overview
Problem
Conventional grommets face challenges in insertability due to the umbrella-shaped covering portion potentially getting caught between the attachment hole and the grommet main body when inserted into the vehicle body panel.
Innovation Solution
A grommet design featuring a tube-shaped portion with an expanded tube portion and a seal portion, along with a protruding portion that connects to the covering portion, allowing the covering portion to deform and reducing the likelihood of being caught, improving insertability by acting as a fulcrum during attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the covering portion is designed to cover the insertion hole in the sound insulation member, then the sealing and sound insulation performance is improved, but the covering portion may get caught between the attachment hole and the grommet main body during insertion, worsening the insertability
Solution Approach 1:
The covering portion is designed to be deformable rather than rigid, allowing it to dynamically change shape during insertion. When the grommet is inserted into the attachment hole, the covering portion deforms to pass through the attachment hole without getting caught, and then returns to its original shape to provide effective sealing and sound insulation.
Solution Approach 2:
The physical state of the covering portion changes from a deformed state during insertion to a restored state during operation. By changing the shape parameter of the covering portion during the insertion process, the grommet achieves both easy insertion and effective sealing performance.
2Reliability
If the covering portion is made rigid to maintain its shape for effective sealing, then the sealing performance is improved, but the likelihood of getting caught during insertion increases, worsening the insertability
Solution Approach 1:
The covering portion transitions from a flexible state during insertion to a rigid state during operation. The deformable design allows easy insertion, while the restored shape provides the rigidity needed for effective sealing and sound insulation against external forces.
3Reliability
If the covering portion is designed to extend fully to ensure complete coverage of the insertion hole, then the sound insulation performance is improved, but the material usage and device complexity increase
Solution Approach 1:
The covering portion uses dynamic deformation to achieve complete coverage functionality with a simpler structure. By allowing the covering portion to deform during insertion and restore afterward, the design achieves effective sound insulation without requiring additional components or complex structural arrangements.
Data Source
AI summary
A first grommet includes a first tube-shaped portion for covering the outer periphery of the wire harness, and an expanded tube portion that expands in diameter and extends from the first tube-shaped portion, and at an end portion on the expanded side, has a seal portion into which the peripheral edge of the attachment hole Pa is to be fit. The covering portion protrudes from the outer peripheral surface of the first tube-shaped portion in a state of being inclined toward the expanded tube portion in the axial direction of the first tube-shaped portion. Also, a first protruding portion that protrudes outward in the radial direction from the outer peripheral surface of the first tube-shaped portion and is connected to the side surface on the expanded tube portion side in the axial direction of the covering portion is formed between the covering portion and the expanded tube portion.