Chair Back Shell With Independent Height and Lumbar Adjustment
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Solution Overview
Problem
Existing office chairs with adjustable back height and lumbar support often feature complex mechanical linkages, increasing manufacturing costs and assembly time, making them less user-friendly and more expensive.
Innovation Solution
The office chair design incorporates a flexible back shell with pivotally connected movement slots and a lumbar adjustment mechanism, allowing users to adjust the chair back height and lumbar support independently through a ratchet mechanism and adjustment cable, simplifying the adjustment process and reducing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If complex mechanical linkages are used to enable chair back height adjustment and lumbar support adjustment, then the adjustment functionality is achieved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The adjustment mechanism is divided into two independent systems: a height adjustment mechanism that moves the entire chair back assembly vertically, and a lumbar support adjustment mechanism that independently adjusts the protrusion of the lumbar support section. This segmentation allows each mechanism to perform a single function with simpler structure, eliminating the need for complex mechanical linkages that would be required to coordinate multiple adjustment functions in a single system.
Solution Approach 2:
A cable-based intermediary system is used to transmit adjustment forces from the user-operated adjustment mechanisms to the chair back components. The cable mechanism acts as a flexible intermediary that simplifies the mechanical connection, allowing independent adjustment of height and lumbar support without requiring complex rigid mechanical linkages between the adjustment controls and the moving parts.
2Adaptability or versatility
If complex mechanical linkages are used for adjustment mechanisms, then adjustment functionality is provided, but manufacturing cost and assembly time increase
Solution Approach 1:
By segmenting the adjustment system into independent height adjustment and lumbar support adjustment mechanisms, each component can be manufactured separately using simpler processes. The modular design allows for standardized cable assemblies, ratchet mechanisms, and mounting brackets that can be produced efficiently and assembled in a straightforward sequence, reducing both manufacturing cost and assembly time compared to integrated complex mechanical systems.
Solution Approach 2:
The patent replaces traditional complex mechanical linkage systems with a cable-based actuation system combined with ratchet mechanisms. This substitution eliminates the need for multiple interconnected mechanical arms, pivots, and fasteners, thereby simplifying manufacturing processes and reducing assembly steps while maintaining the required adjustment functionality.
3Ease of operation
If independent adjustment of chair back height and lumbar support is implemented, then user customization is enhanced, but the adjustment mechanism complexity increases
Solution Approach 1:
The adjustment system is segmented into two independently operable mechanisms: a height adjustment mechanism with its own cable and ratchet system, and a lumbar support adjustment mechanism with a separate cable and ratchet system. This segmentation enables users to independently adjust chair back height and lumbar support protrusion without interfering with each other, providing enhanced customization capability while keeping each individual mechanism simple and intuitive to operate.
Solution Approach 2:
The ratchet mechanisms in both adjustment systems are designed to automatically lock into place at predetermined intervals, providing self-servicing functionality that maintains adjustment positions without requiring additional locking actions from the user. This self-locking feature simplifies the user interface while enabling independent customization of both height and lumbar support.
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
This design enables easy and independent adjustment of chair back height and lumbar support, reducing manufacturing complexity and costs while enhancing user convenience and customization.
Implementation Method 1
The lumbar adjustment mechanism includes an adjustment shaft that is operable to retract and extend the cable, thereby adjusting the position of the bottom end of the flexible back shell
Implementation Method 2
The ratchet mechanism includes a series of spaced ratchet teeth and a pawl that is movable between the ratchet teeth to lock the flexible back shell in a desired vertical position
Implementation Method 3
The back support yoke is pivotally connected to the base through the support bracket
Data Source
AI summary
An office chair including a chair back assembly that is independently adjustable to adjust the vertical height of the chair back and to provide lumbar support. The chair back assembly includes a flexible back shell that is movable vertically along a back support yoke. The vertical movement of the flexible back shell adjusts the vertical height of the chair back assembly relative to the seat. The chair back assembly further includes a lumbar adjustment mechanism having an adjustment cable connected to a bottom end of the flexible back shell. Operation of the lumbar adjustment mechanism moves the bottom end of the flexible back shell vertically within a pair of spaced lower movement slots. The movement of the bottom end of the flexible back shell increases the amount that the flexible back shell protrudes from the back support yoke, thereby increasing the lumbar support.