Chair Footrest Ring Constricting Sleeve for Stable Tube Grip
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Solution Overview
Problem
Conventional footrest rings in chairs are prone to instability and loosening due to point contact with the center tube and deformation of threaded holes, making them difficult to adjust, especially for women and children.
Innovation Solution
A constricting device featuring a conical sleeve and conical constricting unit with axial grooves and non-slip pads, allowing the footrest ring to securely attach to the center tube by mutual pressing, providing adjustable stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a screw member is used to fix the footrest ring to the center tube, then the footrest ring can be attached to the chair, but the footrest ring becomes unstable and may drop when subjected to downward treading force greater than the sustaining force of the screw member
Solution Approach 1:
The fixing mechanism is divided into multiple independent gripping elements (screw member with gripping portion, and separate gripping members) that work together to provide distributed contact and enhanced holding capability, preventing the single-point failure mode of conventional screw fixation
Solution Approach 2:
The screw member features an asymmetric head structure with a gripping portion that engages with gripping members in a specific orientation, creating a mechanically interlocked configuration that resists downward forces more effectively than symmetric conventional screw heads
2Ease of manufacture
If the footrest ring is made of integral plastic to reduce cost, then manufacturing cost is reduced, but the threaded hole becomes deformed and damaged after repeated use, causing the footrest ring to loosen and fall off
Solution Approach 1:
The threading function is extracted from the footrest ring body and relocated to separate gripping members that engage with the footrest ring. This eliminates repeated collision between the threaded hole and screw member, preventing deformation and damage of the threaded hole while maintaining the integral plastic construction of the footrest ring
Solution Approach 2:
Instead of screwing the screw member into a threaded hole in the footrest ring (conventional approach), the invention inverts the engagement mechanism: the gripping members on the screw member engage with corresponding gripping portions on the footrest ring outer surface, eliminating the need for a threaded hole in the footrest ring itself
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 constricting device ensures stable fixation and prevents slipping of the footrest ring, allowing for easy adjustment by releasing the constricting force when moving upward, enhancing user comfort and usability.
Implementation Method 1
By mutual restraint and relative pressing of the conical sleeve of the footrest ring and the conical constricting main body of the constricting unit, the footrest ring can be firmly fixed on the center tube of the chair
Implementation Method 2
when the footrest ring is pressed downward by treading, the conical sleeve of the footrest ring will press the conical constricting main body and make it constricted to closely hold the center tube of the chair
Data Source
AI summary
A constricting device for the footrest ring of a chair includes a constricting unit assembled between the center tube of a chair and the conical sleeve of a footrest ring. The constricting unit consists of a constricting main body and a fixing ring combining the constricting main body and the sleeve of the footrest ring. The constricting main body is a conical body fitted with the conical sleeve of the footrest ring, having its center bored with a fitting hole to be fitted around the center tube of the chair and its circumferential wall cut with plural openings. When the footrest ring is pressed downward by treading, the conical sleeve of the footrest ring will press the conical constricting main body and make it constricted to closely hold the center tube of the chair, able to stably fix the footrest ring on the center tube of the chair.