Grommet Deformation Absorption for Water-Blocking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing grommets with corrugated tube sealing ribs at equal intervals increase section stiffness, leading to deformation and reduced water-blocking performance due to the fastening of a fastening member.
Innovation Solution
A grommet with a cylindrical shape and accordion armoring member, featuring a fastening fixing portion with protruding and recessed shapes, including a no-protrusion portion between end and fixed-side protruding portions, and circumferential dividing portions to absorb deformation and improve water-blocking performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If corrugated tube-side sealing ribs are arranged at equal intervals on the inner peripheral face of the grommet, then water-blocking performance is improved, but section stiffness increases causing deformation of the end portion
Solution Approach 1:
The sealing ribs are segmented into two groups: a first plurality of sealing ribs arranged at equal intervals for water-blocking, and a second plurality of sealing ribs arranged at different intervals for reduced stiffness. This segmentation allows different portions of the grommet to have different functional characteristics.
Solution Approach 2:
Different regions of the grommet are given different local qualities: the region with equally-intervalled sealing ribs provides high water-blocking performance, while the region with non-equally-intervalled sealing ribs provides flexibility and deformation absorption. Each local region is optimized for its specific function.
2Manufacturing precision
If fastening member is used to fix the corrugated tube, then positioning accuracy is improved, but deformation of the fastening fixing portion occurs
Solution Approach 1:
The interval parameter of the sealing ribs in the second plurality is changed from equal intervals to non-equal intervals. This parameter change allows the structure to absorb deformation while maintaining the fastening function, as the non-uniform distribution creates flexibility in the fastening fixing portion.
3Reliability
If section stiffness is increased by sealing ribs, then sealing performance is improved, but deformation influence from fastening reaches the end portion
Solution Approach 1:
The sealing ribs are divided into two segmented groups with different interval patterns. The first group provides sealing performance, while the second group with non-equal intervals creates zones of varying stiffness that absorb and isolate deformation influences, preventing them from reaching the end portion.
Solution Approach 2:
The non-equally-intervalled sealing ribs act as an intermediary element between the fastening fixing portion and the end portion. They absorb and dissipate deformation forces, serving as a buffer that protects the end portion from deformation influence while maintaining sealing integrity.
Data Source
AI summary
There is provided a grommet with water-blocking performance improved by suppression of deformation of a rear end caused by deformation of a fastening fixing portion. The grommet includes: a rear band mounting portion 415 which fastens and fixes a portion displaced from the rear end and overlapping a corrugated tube 5 fitted in the grommet by using a band-shaped binding band 8; and a plurality of rear end-side annular protruding portion 411, first fixed-side annular protruding portion 412, and second fixed-side annular protruding portion 413 protruding from an inner peripheral face and extending in a circumferential direction and disposed along a front-rear direction X so as to be fitted with the corrugated tube 5 by use of protruding and recessed shapes. The rear end-side annular protruding portion 411 is disposed close to the rear end, the first fixed-side annular protruding portion 412 and the second fixed-side annular protruding portion 413 are disposed at a predetermined interval on an inner peripheral face of the rear band mounting portion 415, and a highly deformation absorbable portion 414 having higher deformation absorbing performance than the rear band mounting portion 415 is provided between the rear end-side annular protruding portion 411 and the first fixed-side annular protruding portion 412.