Vehicle Sun Visor Slide Mechanism Backlash Prevention
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Solution Overview
Problem
Conventional vehicle sun visors experience backlash in the slide cover mechanism, which affects the smooth operation and durability of the sun visor.
Innovation Solution
The vehicle sun visor incorporates a slide mechanism with main guide rails, resin springs, and auxiliary guide rails, along with first and second protrusion portions to guide and hold the slide cover at open and closed positions, preventing backlash and plastic deformation of the resin springs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a slide mechanism is used to allow the slide cover to slide between open and closed positions, then the mirror surface can be exposed or covered, but backlash occurs during sliding
Solution Approach 1:
The guide rails are segmented into main guide rails and auxiliary guide rails, with each serving specific functions. The main guide rails provide primary guidance while the auxiliary guide rails engage with the resin springs to prevent backlash, creating a segmented guidance system that addresses both operability and reliability
Solution Approach 2:
Resin springs are introduced as intermediary elements that engage with the auxiliary guide rails. These springs act as mediators between the slide cover and the guide rails, providing elastic engagement that eliminates backlash while maintaining smooth sliding operation
2Reliability
If resin springs are used in the position holding mechanism to hold the slide cover at open and closed positions, then positioning is achieved, but plastic deformation of the resin springs may occur
Solution Approach 1:
The dimensions of the resin springs and guide rails are carefully controlled within specific parameter ranges. The distance between auxiliary guide rails is set to be smaller than the distance between main guide rails, and the protrusion portions are positioned at specific distances, ensuring the resin springs operate within elastic deformation limits while maintaining position holding capability
Solution Approach 2:
The auxiliary guide rails are positioned to engage with the resin springs before the main guide rails' protrusion portions. This beforehand engagement cushions the resin springs, preventing excessive deformation and plastic damage when the slide cover reaches the open or closed positions
3Reliability
If the distance between resin springs in natural state is greater than the distance between main guide rails, then backlash is prevented, but the resin springs are constantly bent
Solution Approach 1:
The guidance function is segmented between main guide rails and auxiliary guide rails. The auxiliary guide rails handle the backlash prevention through engagement with resin springs, while the main guide rails provide primary structural support, allowing the resin springs to remain relatively straight and reducing constant bending stress
Solution Approach 2:
The resin springs only need to engage with the auxiliary guide rails for backlash prevention, not continuously engage with main guide rails. This partial action approach prevents excessive constant bending while still achieving backlash elimination when needed
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
This configuration effectively prevents backlash during sliding and maintains the slide cover at desired positions without causing plastic deformation of the resin springs, enhancing the operational reliability and longevity of the sun visor.
Implementation Method 1
a pair of resin springs formed at the opposite edges of the slide of the slide cover... the first protrusion portions restricting sliding of the resin springs so as to hold the slide cover at the closed position... the second protrusion portions restricting sliding of the resin springs so as to hold the slide cover at the open position
Data Source
AI summary
A mirror unit includes a frame provided separately from or integrally with the one half body, a mirror and slide cover attached to the frame, a slide mechanism that allows slide cover to slide between an open position at which a mirror surface of the mirror is exposed and a closed position at which the slide covers the mirror surface of mirror, relative to the frame, and a position holding mechanism capable of holding slide cover via the slide mechanism at the closed and open position. W1, a distance between pair of resin springs in a natural state>W3, a distance between pair of main guide rails 41>W5, respective distances between the protrusion portions facing each other at the pair of main guide rails, and W3, the distance between pair of main guide rails 41>W4, a distance between the pair of auxiliary guide rails.