Foot ring structure for a chair
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Solution Overview
Problem
Existing foot ring designs for chairs face challenges in balancing holding strength and cost, with high-cost levered quick release devices and limited claw plates leading to increased maintenance and waste, while requiring a cost-effective solution that maintains operating convenience.
Innovation Solution
A foot ring structure featuring a bushing with a conic inner surface and movable braking blocks that can be independently replaced, allowing for adjustable positioning and braking without the need for a high-cost levered quick release device, where the bushing and braking blocks interact to provide secure fastening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a levered quick release device is used to implement sliding and positioning of the foot ring, then holding strength and operating convenience are improved, but manufacturing cost increases significantly
Solution Approach 1:
The quick release device is divided into separate functional components: a braking block with friction surface that contacts the post, a positioning base with guide slots, and a foot ring with integrated sleeve. This segmentation allows each component to be manufactured independently using simpler, lower-cost processes while maintaining the overall functionality of sliding and positioning.
Solution Approach 2:
The braking block is designed as a replaceable component that can be independently manufactured and replaced when worn. This allows the use of simpler, cheaper materials and manufacturing methods for the braking block specifically, rather than requiring expensive materials and processes for the entire assembly. The braking block can be replaced without replacing the entire quick release device.
2Strength
If claw plates are integratedly connected to the inner sleeve to increase holding force, then fastening capability is improved, but the deforming range is limited and maintenance cost increases when elastic fatigue occurs
Solution Approach 1:
The braking block is separated from the inner sleeve and positioning base, forming an independent replaceable component. This segmentation allows the braking block to be replaced individually when it shows signs of elastic fatigue or wear, without needing to replace the entire inner sleeve or positioning base assembly, thereby reducing maintenance costs.
Solution Approach 2:
The braking block is designed as a consumable component that can be discarded when worn out and replaced with a new one. The reusable components (inner sleeve, positioning base) are retained and recovered for continued use. This approach reduces maintenance costs by allowing selective replacement of only the worn braking block rather than the entire assembly.
3Strength
If the inner sleeve is machined to provide a thread for the claw plate, then fastening capability is improved, but manufacturing cost increases
Solution Approach 1:
The threading function is separated from the inner sleeve and transferred to the braking block. The braking block is manufactured with external threads, while the positioning base provides a corresponding threaded hole. This segmentation allows the threading to be implemented on the smaller, simpler braking block component rather than requiring expensive threading of the entire inner sleeve.
Solution Approach 2:
The braking block with integrated threads is designed as a cheaper, replaceable component compared to providing threads on the inner sleeve. By placing the threads on the disposable braking block rather than the more expensive inner sleeve, the overall manufacturing cost is reduced while maintaining fastening capability.
4Strength
If claw plates are used to press the post for fastening, then holding force is improved, but the deforming range is limited due to connection to the inner sleeve
Solution Approach 1:
The braking block is separated from the inner sleeve and positioned within the positioning base. This segmentation gives the braking block independent movement capability, allowing it to deform and press against the post with greater range of motion without being constrained by the inner sleeve structure. The guide slots in the positioning base enable the braking block to move freely in the required directions.
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 solution effectively balances holding strength and cost, reduces maintenance expenses by allowing separate replacement of braking blocks, and maintains convenience in adjusting the foot ring's position, thereby enhancing price competitiveness and minimizing waste.
Implementation Method 1
The outer surfaces of the braking blocks jointly form a conic shape corresponding to the inner surface of the bushing. The bushing is moved with the foot ring. The bushing presses the braking blocks to move toward the post to fasten the foot ring onto the post when the foot ring is rotated toward a direction.
Data Source
AI summary
A chair includes a seat, a post, a foot ring, a bushing and a positioning base. The post is connected to the seat. The foot ring has a ring body and a sleeve. The bushing is fastened in the sleeve and has a conic inner surface. The inner surface tapers upward. The inner surface has an inner thread. The positioning base is of a tubular shape and axially fastened onto the post. The positioning base has openings. Each opening is embedded by a braking block. An outer surface of each braking block has an outer thread. The outer surfaces of the braking blocks jointly form a conic shape corresponding to the inner surface of the bushing. The outer thread screws with the inner thread. The bushing presses the braking blocks to move toward the post to fasten the foot ring onto the post when the foot ring is rotated.