Grommet Dual Conical Flange Guide for Panel Insertion
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Solution Overview
Problem
Existing grommets fail to maintain a sufficient waterproof condition when inserted into through-holes with burrings on vehicle body panels due to improper insertion angles, leading to buckling and inadequate contact pressure, which compromises the seal between the engine compartment and the inner vehicle space.
Innovation Solution
A grommet design featuring a molded resin inner and a grommet body made of rubber or elastomer, with a first conical flange portion and a second conical flange portion that expand at different angles, where the second flange acts as a guide to press out the first flange and ensure proper contact with the vehicle body panel, enhancing the seal by increasing the adhesion between the seal lip and the panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the grommet is inserted into a through-hole with a burring, then the waterproof condition is improved, but the grommet may buckle and fail to maintain proper contact pressure due to improper insertion angles
Solution Approach 1:
The conical flange portion is designed with a specific conical angle that allows it to automatically guide and align itself with the through-hole during insertion. This preliminary geometric configuration ensures that even if the insertion angle is initially improper, the conical surface will self-align and press out properly against the burring, maintaining reliable contact pressure and waterproof sealing without requiring precise manual alignment
2Ease of operation
If the grommet is inserted with improper angle, then the insertion operation becomes easier, but the contact pressure becomes insufficient leading to inadequate sealing
Solution Approach 1:
The conical flange portion is designed with a specific conical angle parameter that transforms the insertion process. This angular parameter allows the flange to convert improper insertion angles into proper contact with the burring through its geometric self-correction mechanism, ensuring that the contact pressure parameter remains sufficient for reliable sealing regardless of initial insertion angle
3Stability of the object's composition
If the conical flange portion contacts the vehicle body panel, then the grommet is secured in position, but the flange may buckle inward reducing contact pressure
Solution Approach 1:
The conical flange portion is pre-configured with a specific conical angle that anticipates and prevents buckling during the insertion process. This preliminary geometric design ensures that as the flange contacts the vehicle body panel, the conical surface geometry naturally directs the contact force outward to press against the burring, preventing inward buckling and maintaining adequate contact pressure for both positioning and sealing functions
Data Source
AI summary
A grommet body includes: a cylinder portion into which a wire harness is inserted; a first conical flange portion which extends onto an outer circumference of the cylinder portion, and is formed in a conical shape expanding toward a vehicle body panel; an annular seal lip which is formed in a shape protruding onto an outer circumferential edge portion of the first conical flange portion, the edge portion being on a surface opposing the vehicle body panel; and a second conical flange portion which extends from an outer circumferential end of the first conical flange portion, and is formed in the conical shape expanding toward the vehicle body panel at a conical angle smaller than the conical angle of the first conical flange portion.