Furniture Positioning Cam Mechanism for Stable Angle Adjustment
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Solution Overview
Problem
Existing chair mechanisms that adjust the inclination of the seating portion and backrest are limited by predetermined synchronism ratios, allowing only fixed or two stable positions, and often result in bulky constructions requiring additional locking mechanisms to prevent movement reversibility.
Innovation Solution
A compact adjustment system using a three-lobe cam mechanism with an eccentric pin and adjustment knob, allowing for multiple stable positions by varying the distance between the seating portion and backrest through rotational movement, ensuring stability and alignment without peripheral thrusts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a cam mechanism is used to adjust chair inclination, then two stable positions are achieved, but continuous adjustment is not possible
Solution Approach 1:
The patent employs a three-lobe cam with curved surfaces instead of traditional flat or angular cam profiles. The specific curvature of the cam lobes creates multiple stable equilibrium positions while maintaining a compact structure, resolving the contradiction between limited discrete positions and continuous adjustment capability
2Adaptability or versatility
If unidirectional adjustment elements are used, then position adjustment is achieved, but bulky construction and additional locking means are required
Solution Approach 1:
The three-lobe cam mechanism is designed to be self-locking through its geometric configuration. The curved surfaces and eccentric pin arrangement automatically maintain contact and prevent reversal without requiring separate locking mechanisms, thereby simplifying the overall construction while maintaining adjustment capability
3Ease of operation
If synchronous mutual rotation mechanism is used, then fixed ratio inclination adjustment is achieved, but independent modification of seating portion inclination is prevented
Solution Approach 1:
The patent separates the adjustment functions by allowing the three-lobe cam to independently control the seating portion inclination relative to the backrest. This segmentation enables the user to adjust the seating angle independently while the backrest maintains its position, breaking the fixed synchronous relationship of traditional mechanisms
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 continuous and stable adjustment of the relative angle between the seating and backrest, providing a prechosen number of stable positions with improved stability and reduced complexity, allowing for ergonomic customization without the need for additional locking means.
Implementation Method 1
A compact adjustment system using a three-lobe cam mechanism with an eccentric pin and adjustment knob, allowing for multiple stable positions by varying the distance between the seating portion and backrest through rotational movement
Data Source
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Figure 5a~7
AI summary
A system for adjusting the relative position between two furniture parts, characterised by comprising: - a first part (2) provided on one side with at least two parallel guide (24) surfaces at a prefixed distance X apart; - a second part (10) facing said first part; - an eccentric multi-lobe cam, (28) the continuous profile of which is composed of tangential curves disposed such as to form an odd number n of pairs of opposing arcs, - each pair of arcs having the same centre of curvature with the sum of the radii of curvature being equal to X, said cam (28) being housed between said two parallel guides (24) and being pivoted to said second part on the eccentric pin, (32) - means for rotating said multi-lobe cam (28).