Chair Armrest Height Locking Structure With Hidden Engagement
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Solution Overview
Problem
Existing height adjustment devices for armrests in chairs face issues such as exposure of engaging portions, poor operability, and increased material costs due to large movement strokes, leading to potential malfunctions and limited design flexibility.
Innovation Solution
A height adjustment device with a movable member, locking mechanism, biasing member, actuating member, and operating lever that allows for smooth operation and locking/unlocking regardless of the up-down position, preventing engaging portion exposure and reducing the likelihood of malfunctions, while maintaining a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the movement stroke of the movable member is made large, then the height adjustment range is improved, but the engaging portions are exposed to the outside and become unseemly
Solution Approach 1:
The guide member is nested inside the movable member, with the engaging portions formed on the guide member. This nesting arrangement allows the engaging portions to be hidden within the movable member's structure, maintaining a clean appearance even when the movement stroke is large. The guide member extends in the up-down direction within the movable member, providing both structural support and the engagement mechanism.
2Length of moving object
If the length of the upper support cylinder and lower support rod are made large, then the movement stroke is improved, but the whole armrest is enlarged and material costs are increased
Solution Approach 1:
The guide member is nested within the movable member, allowing the engagement mechanism to be integrated into the existing structure. This eliminates the need for additional external components, reducing material usage and costs while maintaining the required movement stroke.
3Ease of operation
If the extension portion of the operating lever is formed elongated downward, then the operating range is improved, but the rotation radius becomes large and precise transmission of operation is difficult
Solution Approach 1:
The engagement function is extracted from the extension portion of the operating lever and transferred to the guide member. The pin on the operating lever simply needs to engage with the engaging portions on the guide member, eliminating the need for a long extension portion. This reduces the rotation radius and improves operational precision while maintaining ease of use.
4Volume of moving object
If the engagement depth near the pivotal attachment portion is made small, then the compactness is improved, but the required rotational angle and operating force fluctuate causing poor operability
Solution Approach 1:
The guide member is positioned such that the engaging portions are distributed along its length, with different engagement depths at different positions. This local variation in engagement depth allows the pin to engage reliably at multiple heights while maintaining consistent operability. The guide member's structure provides appropriate engagement depth at each location, ensuring uniform operating characteristics throughout the movement stroke.
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 solution ensures smooth operation and reliable locking/unlocking of the armrest at any height, minimizing the risk of errors and maintaining a compact, cost-effective design by preventing engaging portion exposure and allowing for flexible attachment positions.
Implementation Method 1
biasing member that is provided at the support and biases the locking member toward the locking position
Implementation Method 2
an operating member that is provided at the movable member and actuates the actuating member so as to move the locking member in the direction of the unlocking position via the actuating member
Data Source
AI summary
An armrest device for a chair includes a lower support rod that rises at a side of a chair seat and has a tubular upper end portion; and an upper support cylinder that has an armrest provided in an upper end thereof, is externally fitted to the lower support rod so as to be slidable in an up-down direction, and has a plurality of engaging portions therein. The armrest is made height-adjustable with respect to the lower support rod by disposing the locking member and a biasing member at an upper end portion of the lower support rod and providing the rotating rod inside the lower support rod.