Foldable Chair Cam Locking for Easy State Conversion
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Solution Overview
Problem
Conventional foldable walking stick chairs are inconvenient to operate between folded and unfolded states due to complex mechanisms, and their manufacturing costs are high due to intricate positioning structures.
Innovation Solution
A foldable chair design featuring a main stick with guide and positioning grooves, a fold unit with a connecting member, upper slider assembly, and a seat unit that allows easy conversion between states through a rotatable member engaging and disengaging from positioning grooves, simplifying the operation and reducing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional screw and sleeve mechanism is used for positioning, then the foldable chair can be retained in folded or unfolded states, but the operation becomes inconvenient
Solution Approach 1:
The patent replaces the conventional screw-threaded sleeve mechanism with a cam and groove mechanism. The cam (rotating member) with its specific profile interacts with the groove on the main stick to provide positioning at different states (folded, unfolded, intermediate) without requiring threaded engagement. This substitution simplifies the operation from rotating a screw to simply rotating a cam, while maintaining reliable positioning through the cam profile geometry.
2Ease of operation
If a complex positioning structure is used to enable easier operation, then the foldable chair can be converted more easily between states, but the manufacturing cost increases
Solution Approach 1:
The cam (rotating member) serves multiple functions: it provides positioning in the folded state, positioning in the unfolded state, and intermediate positioning states, all through a single component. The groove on the main stick also serves multiple purposes by guiding the cam rotation and defining the positioning points. This multi-functionality reduces the need for multiple separate positioning components, thereby reducing manufacturing cost while maintaining ease of operation.
Solution Approach 2:
The patent uses changes in the cam profile geometry (radius, shape) to achieve different positioning states. By varying the cam profile parameters, the same basic mechanism can provide positioning at multiple discrete states without requiring additional components. This parameter-based approach simplifies the structure compared to using multiple discrete positioning elements, reducing manufacturing complexity and cost.
3Ease of manufacture
If a simple mechanism is used for state conversion, then the manufacturing cost is reduced, but the positioning reliability may be compromised
Solution Approach 1:
The cam profile is designed to create stable equilibrium positions at both the folded and unfolded states. The geometry of the cam and groove interaction ensures that at these positioning points, the forces are balanced, creating stable resting positions similar to equipotential points. This design ensures that once positioned, the chair remains reliably in that state without requiring additional locking mechanisms, maintaining reliability while keeping the structure simple.
Data Source
AI summary
A foldable chair includes a support unit, a fold unit and a seat unit. The support unit includes a main stick having a positioning groove. The fold unit includes a connecting member connected to the main stick and an upper slider assembly movable along the main stick. The seat unit is connected to the upper slider assembly. The upper slider assembly is operable to engage the positioning groove for preventing the fold unit from converting between an unfolded state and a folded state, and to be disengaged from the positioning groove so as to permit the fold unit to convert between the unfolded and folded states.