Chair Back Tilt Mechanism With Balanced Spring Transmission
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Solution Overview
Problem
Existing back tilt adjustment mechanisms in office chairs require excessive force for operation, are prone to jamming, and can lead to unbalanced transmission and damage due to single-sided force transmission, causing inconvenience and potential structural issues.
Innovation Solution
A flexible back tilt adjustment device featuring a seat connected to a back via a first rod and an elasticity set, with a pressing rod, pushing block, rotating rod, and second springs, allowing for effort-saving adjustment through a control module with gears and linkages that distribute force effectively and reduce friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a spring is used between cushion and back for tilt adjustment, then the back can be adjusted, but the spring tends to elastic fatigue
Solution Approach 1:
The patent introduces a transmission mechanism with transmission rod, driving block, and link set as intermediaries between the adjustment rod and the back tilt mechanism. This mediator system converts rotational motion to linear motion and distributes forces through multiple components, preventing direct stress concentration on a single spring element and reducing elastic fatigue.
2Adaptability or versatility
If adjustment rod and transmission rod with link set are used for flexible tilt adjustment, then the back can be adjusted flexibly, but rotating the adjustment rod needs larger force
Solution Approach 1:
The patent transforms the adjustment mechanism from direct linear force transmission to rotational force transmission through the adjustment rod. By converting the adjustment input to rotational motion that drives the transmission rod through threaded engagement, the mechanism leverages mechanical advantage to reduce the force required while maintaining flexible adjustment capability.
3Ease of operation
If link set is used to change direction of force, then flexible adjustment is achieved, but when link set jams, the whole adjustment structure cannot work
Solution Approach 1:
The patent segments the force transmission path into multiple independent components: adjustment rod, driving block, transmission rod, and link set. This segmentation allows individual components to be replaced or maintained independently, and the modular design reduces the probability of complete system failure from jamming by isolating potential failure points.
4Ease of operation
If single-sided transmission from link set to transmission rod is used, then force direction is changed, but the transmission is easy to be unbalanced causing damage
Solution Approach 1:
The patent employs asymmetric threading on the transmission rod with different thread directions (left-handed and right-handed threads) on opposite sides. This asymmetric design creates balanced force distribution during rotation, preventing unbalanced single-sided transmission and reducing the risk of damage to the transmission components.
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
Enables effortless back tilt adjustment with reduced risk of jamming and structural damage, providing a balanced and smooth operation by leveraging the elasticity of springs and gear engagement to minimize user effort.
Implementation Method 1
A first spring is passed through by the pressing rod and stopped by the base... Two second springs are passed through by the rotating rod and nipped between the pressing blocks and the edge plates
Implementation Method 2
Two pressing blocks with a threaded hole are passed by the rotating rod and separately screwed with the rotating rod
Data Source
AI summary
The adjustment device includes a seat connected to a back by a first rod and an elasticity set. The elasticity has a base connected to the first rod. A pressing rod is connected to the base. A first spring is passed through by the pressing rod and stopped by the base. A pushing block is connected to the pressing rod and the first spring. A rotating rod passes through the seat. Two pressing blocks with a threaded hole are passed by the rotating rod and separately screwed with the rotating rod. Two second springs are passed through by the rotating rod and nipped between the pressing blocks and the edge plates.