External Back Spring Assembly for Stackable Chair Recline Control
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Solution Overview
Problem
Existing stackable chairs with flexible backrests require additional cross structures or spring support members to limit reclining movement, which increases the width or depth of the support frame and complicates assembly and disassembly.
Innovation Solution
A flexible back support frame mechanism with spring units that are directly attached to the exterior of the back support frame and seat assembly, allowing reclining movement while preventing excessive forward movement, eliminating the need for additional cross structures or spring support members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional spring members and U-shaped brackets are added to limit excessive flexing during reclining movements, then the stability and control of the backrest is improved, but the device complexity and the width or depth of the support frame members increase
Solution Approach 1:
The patent combines the functions of multiple spring members and U-shaped brackets into a single integrated spring assembly. This spring assembly directly attaches to the exterior surfaces of the back support frame and seat assembly, eliminating the need for additional cross structures or support members while maintaining the ability to control backrest movement during reclining.
Solution Approach 2:
The invention extracts and eliminates unnecessary internal cross structures and spring support members from the chair frame. By attaching spring members directly to the exterior of existing frame members, the patent removes redundant components that previously increased device complexity and frame dimensions.
2Reliability
If spring member ends are enclosed by U-shaped brackets to limit angular movement, then the reliability of the spring member is improved, but the ease of manufacture and assembly is worsened due to full disassembly requirements
Solution Approach 1:
The spring assembly is designed as a separable unit that can be independently attached and detached from the chair frame. This segmentation allows the spring assembly to be manufactured separately and installed without full disassembly of the chair, improving ease of manufacture and maintenance while maintaining spring member protection.
Solution Approach 2:
The spring assembly is pre-assembled with all necessary components (spring members, brackets, and mounting elements) before installation. This preliminary assembly simplifies the manufacturing process and enables easy installation by simply attaching the complete assembly to the exterior of the back support frame and seat assembly.
3Reliability
If additional spring members are positioned parallel to existing spring members with greater width or depth brackets, then the reliability for rigorous use is improved, but the area of the support frame members must increase
Solution Approach 1:
Instead of adding spring members in parallel along the same dimension (which would increase frame width or depth), the patent utilizes the exterior surface area of existing frame members in a different dimensional space. The spring assembly attaches to the outer surfaces of the back support frame and seat assembly, providing additional support capacity without expanding the overall frame dimensions.
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 enables repetitive reclining and rebounding of the back support frame without requiring additional spring support components, enhancing flexibility and stability while maintaining structural integrity and simplifying assembly.
Implementation Method 1
Each spring member is capable of repetitive flexing and includes an inherent bias to rebound to a non-flexed position
Data Source
AI summary
Disclosed is a stackable chair containing a flexible back support frame mechanism that includes an improved spring system designed to allow reclining movement of a back support frame relative to a seat assembly. The back support frame and seat assembly are connected using right and left spring members disposed in a substantial surface-to-surface contact relationship with the seat assembly and back support frame members.