Wiper Device Water Receiving Cap Axial Overlap
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Solution Overview
Problem
Conventional wiper devices face issues with the water receiving cap separating from the pivot holder due to friction, leading to potential disengagement and rotation, especially when the cap is made of resin and the holder is made of metal, causing assembly damage.
Innovation Solution
The wiper device incorporates a pivot shaft with a washer and a water receiving cap featuring a tubular boss portion and an umbrella portion, where the washer is fixed to the pivot shaft, and the boss portion overlaps the washer, with an insertion projection that opposes the mounting leg without engaging it axially, ensuring secure coupling and preventing rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the water receiving cap is made of resin and fitted onto the metal pivot holder, then the cap can be easily manufactured and assembled, but the projection is scraped during assembly causing decreased engagement force and potential separation
Solution Approach 1:
A resin layer is introduced as an intermediary material between the metal pivot holder and the resin projection. This resin layer acts as a protective mediator that prevents direct metal-resin friction during assembly, eliminating the scraping of the projection while maintaining the ease of manufacture of the resin cap.
Solution Approach 2:
The surface properties of the pivot holder are changed by coating it with resin instead of using bare metal. This parameter change in surface material reduces the friction coefficient between the pivot holder and the projection during assembly, preventing projection scraping while maintaining structural integrity.
2Strength
If the projection is engaged with the engagement groove to prevent movement, then the cap is securely fixed, but the friction during assembly scrapes the projection making it easily disengaged
Solution Approach 1:
The resin layer serves as a mediator that protects the projection from metal friction during the engagement process. This allows the projection to be firmly engaged with the engagement groove without being scraped, maintaining both engagement strength and long-term engagement reliability.
Solution Approach 2:
The resin coating on the pivot holder provides beforehand cushioning protection for the projection during the assembly process. This protective layer prevents the harmful friction that would otherwise occur during engagement, ensuring the projection maintains its engagement force over time.
3Ease of operation
If the projection restricts movement during assembly, then the cap is positioned correctly, but the friction causes the projection to be easily separated by vibration during transportation
Solution Approach 1:
The resin layer acts as a protective intermediary during the assembly process, allowing the projection to be easily inserted and positioned without friction-induced damage. This ensures both ease of assembly and long-term assembly stability by preventing projection wear that would lead to loosening under vibration.
Solution Approach 2:
Changing the surface parameter of the pivot holder from metal to resin reduces the coefficient of friction during assembly operations. This allows for easier insertion and positioning of the projection while maintaining stable engagement that resists vibration-induced loosening during transportation.
Data Source
AI summary
A wiper device includes a pivot shaft, a pivot holder, a water receiving cap and a washer. The pivot holder includes a pivot support portion and a mounting leg. The pivot support portion pivotally supports the pivot shaft. The water receiving cap includes a boss portion and an umbrella portion. The boss portion is fitted onto the pivot support portion. The washer is fixed to a circumference of the pivot shaft at a portion projecting from a distal end of the pivot support portion. At least part of the boss portion overlaps the washer in an axial direction. The umbrella portion includes a projection that projects in the axial direction. The projection opposes the mounting leg in a circumferential direction without engaging the mounting leg in the axial direction.