Office Chair Swivel Mechanism With Lever-Based Force Adjustment
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Solution Overview
Problem
Existing office chair mechanisms struggle to provide adjustable swivel force that is suitable for both light and heavy users, as they often require a compromise between spring reliability and compactness, leading to inadequate force adjustment and ergonomic issues.
Innovation Solution
A compact and economical adjustment device using a lever mechanism with a cam system and a fulcrum that adjusts the position of a helical spring, allowing for wide force adjustment by varying the lever arm lengths, enabling easy and quick ergonomic adjustments for different user weights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If compression springs with adjustment knobs are used to modify swivel force, then the preload can be adjusted, but the adjustment mechanism becomes bulky and complex
Solution Approach 1:
The invention changes the physical parameters of the spring system by replacing compression springs with torsion springs, and adjusting the lever arm length rather than spring preload. This parameter change allows for a more compact adjustment mechanism while achieving the same force modification goal.
Solution Approach 2:
The invention substitutes the traditional compression spring mechanism with a torsion spring and lever system. This mechanical substitution eliminates the need for bulky adjustment knobs and complex preload adjustment mechanisms, achieving a simpler and more compact design.
2Force
If torsion springs with preload adjustment elements are used, then the swivel force can be modified, but the adjustment mechanism becomes bulky and expensive
Solution Approach 1:
The invention extracts and eliminates the bulky preload adjustment elements from the torsion spring system. By using a lever mechanism that acts on the spring's mounting point rather than requiring direct spring preload adjustment, the design removes unnecessary complexity and bulk.
Solution Approach 2:
The invention introduces a lever as an intermediary mechanism between the user's adjustment action and the torsion spring. This lever acts as a mediator that translates small adjustment movements into effective force changes, eliminating the need for complex direct spring adjustment elements.
3Adaptability or versatility
If the spring preload is adjusted to accommodate different user weights, then the swivel force can be modified, but the adjustment range is limited by spring reliability and compactness
Solution Approach 1:
The invention makes the lever arm length dynamic and adjustable, allowing the system to adapt to different user weights and preferences. This dynamic adjustment capability expands the versatility range without compromising spring reliability, as the spring itself remains within its optimal operating parameters.
Solution Approach 2:
The invention creates a universal adjustment mechanism that serves multiple functions: it accommodates different user weights, maintains spring reliability, and provides a compact design. The lever-based system achieves multi-functionality by decoupling the adjustment range from spring preload limitations.
4Device complexity
If a fixed spring force is used, then the mechanism remains simple and compact, but it cannot accommodate both light and heavy users ergonomically
Solution Approach 1:
The invention introduces dynamic adjustability through the lever mechanism, allowing the system to adapt to different users while maintaining overall simplicity. The lever arm length can be adjusted to change the mechanical advantage, providing ergonomic suitability for both light and heavy users without complicating the core mechanism.
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 provides versatile and ergonomic force adjustment, reducing constructional complexity and costs while ensuring reliable performance for both light and heavy users, with a mechanism that doubles or triples the swivel resistance, maintaining chair compactness.
Implementation Method 1
A compact and economical adjustment device using a lever mechanism with a cam system and a fulcrum that adjusts the position of a helical spring, allowing for wide force adjustment by varying the lever arm lengths
Implementation Method 2
the other end 36 of the lever 28 acts on a helical spring 38
Implementation Method 3
for example by using a simple cam device 34 which moves the contact element (pin) 30
Data Source
AI summary
An office chair mechanism provided with a device for adjusting the swivel force includes a fixed part secured to the chair base, movable parts secured to the seating portion and to the back rest (22) of the chair, and an elastic element which opposes the weight of the chair user, a lever having contact surfaces which interact with said fixed part by means of a fulcrum having a movable contact element interposed between the end acting on the elastic element and the other end to which the movable parts are pivoted, and an adjustment element which causes only the movable contact element to move but without modifying the position of the elastic element and of the lever.