Vehicle Grommet Seal Structure for Improved Water Sealing
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Solution Overview
Problem
Existing grommets fail to effectively improve water sealing properties between vehicle body panels and wire harnesses, leading to potential water ingress into vehicle cabins.
Innovation Solution
A grommet design featuring an annular seal portion with inclined first and second lip portions that create a negative pressure space for suction adherence to the vehicle body panel, combined with a rigid inner member for enhanced compression and rigidity, preventing water ingress and maintaining seal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional seal portion is used in the grommet, then the structure is simple, but the water sealing property is insufficient
Solution Approach 1:
The seal portion is divided into multiple functional segments: a first lip portion extending radially outward to contact the vehicle body panel, and a second lip portion extending radially inward to contact the wire harness. This segmentation allows each lip to perform its specific sealing function, improving water sealing property while maintaining reasonable structural complexity
Solution Approach 2:
The seal portion utilizes three-dimensional spatial configuration by extending lips in different radial directions (outward and inward) from the grommet body. This dimensional approach creates multiple sealing interfaces simultaneously, enhancing water sealing effectiveness without simply increasing the number of separate components
2Reliability
If the grommet is tightly attached to the vehicle body panel, then water sealing property improves, but compression of the grommet increases
Solution Approach 1:
The first lip portion is designed with specific local properties to contact the vehicle body panel, while the second lip portion has different local properties to contact the wire harness. The inclined configurations of both lips distribute compression forces locally to their respective contact surfaces, preventing excessive compression of the entire grommet while maintaining tight sealing contact
3Strength
If a rigid inner member is added to enhance compression resistance, then the grommet strength improves, but the device complexity increases
Solution Approach 1:
The rigid inner member is merged with the flexible grommet body to form an integrated assembly. The inner member provides compression resistance and structural support, while the grommet body maintains sealing flexibility. This combination allows the grommet to resist compression forces without requiring separate reinforcement components, balancing strength enhancement with structural simplicity
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 grommet effectively improves water sealing properties by ensuring tight contact and preventing water from entering the vehicle cabin, while minimizing compression risks and simplifying attachment, thus enhancing the overall sealing performance.
Implementation Method 1
the space surrounded by the first lip portion, the second lip portion, and the vehicle body panel is brought into a negative pressure (substantially vacuum), and it is therefore possible to cause the seal portion to adhere by suction to the vehicle body panel
Data Source
AI summary
One aspect of the present disclosure provides a grommet that can improve water sealing property. A grommet main body according to one aspect of the present disclosure includes an opposing portion that opposes a circumferential portion of an attachment hole of a vehicle body panel and an annular seal portion that is provided in the opposing portion and is brought into tight contact with the vehicle body panel. The seal portion includes an annular first lip portion that extends from the opposing portion toward the vehicle body panel and an annular second lip portion that extends from the opposing portion toward the vehicle body panel and is provided radially inward of the first lip portion. The first lip portion is inclined radially outward toward the tip end of the first lip portion, and the second lip portion is inclined radially inward toward the tip portion of the second lip portion.