Folding Chair Backrest Locking for Stable Load-Bearing Use
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Solution Overview
Problem
Conventional folding chairs lack a secure locking mechanism that ensures the chair remains stable when unfolded and under weight, and they do not compact efficiently for storage.
Innovation Solution
The design incorporates a backrest that pivots to a locked position when force is applied to the seating member, with structural members flexing to 'snap' into place, and a configuration that allows the chair to fold into a thinner, more compact shape with a hook for hanging, utilizing specific pivot connections and linkages between the backrest, seat, and legs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional folding chair designs are used with rigid backrest and simple pivot connections, then the chair structure is simple and easy to manufacture, but the chair lacks stability and may fold under weight when unfolded
Solution Approach 1:
The patent applies dynamics by making the backrest movable rather than rigid, allowing it to pivot and lock into position. The backrest transitions from a static component to a dynamic one that can move between folded and locked positions, providing stability when needed while maintaining simplicity when not in use
Solution Approach 2:
The chair structure utilizes the user's weight as a locking mechanism. When a person sits on the chair, their weight causes the backrest to pivot and lock into place automatically, eliminating the need for separate locking mechanisms or complex fastening systems
2Shape
If the backrest is made rigid and connected directly to front and rear legs, then the manufacturing process is simple, but the chair cannot achieve a compact folded shape and lacks secure locking
Solution Approach 1:
The backrest is segmented from the leg structure through pivot connections, allowing independent movement. This segmentation enables the backrest to fold down independently while the legs maintain their structural integrity, achieving compact storage without complicating the overall manufacturing process
Solution Approach 2:
When folded, the backrest nests against the leg structure, creating a compact configuration. The backrest folds down to rest against the rear legs, minimizing the overall footprint and achieving a space-efficient storage form
3Reliability
If simple pivot connections are used between backrest and legs, then the chair is easy to assemble, but the chair cannot prevent folding under weight or tilting
Solution Approach 1:
The connection mechanism uses the chair's own structure and the user's weight to create the locking action. The backrest pivots on connections to the legs, and user weight automatically drives the backrest into the locked position, providing security without requiring external locking components
Solution Approach 2:
The pivot connections act as intermediaries between the backrest and legs, allowing controlled movement while maintaining structural integrity. These connections enable the backrest to rock and lock into position, providing secure attachment without rigid fixed connections
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 chair provides enhanced stability when in use, prevents folding under weight or tilting, and achieves a more compact storage form, ensuring secure locking and easy carrying or hanging.
Implementation Method 1
structural members flexing to 'snap' into place
Data Source
AI summary
A folding chair having seat, backrest, front leg, and rear leg interconnected with backrest pivoted to front leg and back leg, and seat pivoted to front leg and back leg so as to lock backrest when chair is unfolded, and when weight is applied to the seat a force is applied further locking the backrest. A modification provides a folding chair with outer and inner frames for locking backrest and rear leg in position when chair is unfolded for use.