Cam-Ratchet Armrest Mechanism for High-Load Incremental Adjustment
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Solution Overview
Problem
Conventional adjustable armrests in furniture fail to withstand load requirements greater than 2,400 N vertically and 1,500 N horizontally due to complex designs with many moving parts, leading to premature wear and breakage, and are costly to manufacture and assemble.
Innovation Solution
An adjustable armrest design featuring a housing with a pivot pin, gear, cam, and ratchet mechanism that allows incremental adjustment between vertical and horizontal positions, using fewer components and materials to enhance load-bearing capabilities and durability without increasing weight or manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional adjustable armrest designs are used, then incremental adjustment between vertical and horizontal positions is achieved, but the device fails to withstand load requirements greater than 2,400 N vertically and 1,500 N horizontally due to complex designs with many moving parts
Solution Approach 1:
The patent combines multiple functions into a single integrated mechanism. The cam structure integrates the adjustment mechanism, locking mechanism, and load-bearing function into one component that works with the ratchet and gear. This merging reduces the number of separate moving parts while maintaining the ability to withstand high loads (greater than 2,400 N vertically and 1,500 N horizontally) because the load is distributed across the integrated mechanism rather than relying on multiple small components.
Solution Approach 2:
The patent segments the adjustment mechanism into discrete incremental positions using the gear and ratchet system. The cam rotates in discrete steps, each step corresponding to a specific armrest angle. This segmentation allows the armrest to be positioned at precise intervals while the integrated cam-ratchet-gear mechanism maintains structural integrity under high load conditions.
2Duration of action of moving object
If conventional adjustable armrest designs with many moving parts are used, then incremental adjustment is possible, but the parts bend, wear and eventually break, resulting in a lifecycle of approximately 10,000 cycles
Solution Approach 1:
By merging the adjustment and locking functions into the integrated cam-ratchet-gear mechanism, the patent eliminates multiple separate moving parts that would otherwise wear and fail independently. The unified structure distributes mechanical stress across robust components designed for durability, extending the lifecycle beyond the conventional 10,000 cycles.
Solution Approach 2:
The patent employs simple, robust components with few moving parts that are easier to manufacture and replace if needed. The cam, ratchet, and gear are designed as durable, wear-resistant components that can withstand repeated use, effectively creating a long-lasting mechanism that reduces the frequency of replacement.
3Ease of manufacture
If conventional adjustable armrest designs are used, then adjustment functionality is achieved, but manufacturing cost and assembly complexity increase
Solution Approach 1:
The patent merges multiple functions into fewer components, directly reducing the total number of parts that need to be manufactured and assembled. The integrated cam structure that incorporates adjustment, locking, and load-bearing functions eliminates the need for separate mechanisms for each function, thereby lowering manufacturing costs and simplifying assembly processes.
Solution Approach 2:
The cam structure serves multiple functions simultaneously: it enables incremental adjustment, provides locking at each position, and bears the mechanical loads. This multi-functionality reduces the overall component count and simplifies the bill of materials, making the device easier and less costly to manufacture.
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 design supports higher load forces while reducing the number of moving parts, extending the armrest's lifecycle and lowering production costs, ensuring reliable operation and improved torsion force support.
Implementation Method 1
a tension spring constantly urging the tail of the ratchet in a direction toward engagement with the gear
Implementation Method 2
A cam ring with an interior surface and an exterior cam surface is also positioned on the pin
Implementation Method 3
A gear is positioned on the pin. The gear has teeth extending across its entire width to define detents
Implementation Method 4
A pivot pin positioned in the housing is supported by each of the bores
Data Source
AI summary
An adjustable armrest includes a housing with opposite walls. Each of the walls has a bore formed in it. The boxes support a pivot pin with a gear so that the armrest is pivotable on the pin. A ratchet with a pawl is pivotably connected to and carried by the armrest. The ratchet is also configured so that the pawl may engage the gear to define incremental ratcheting movement of the armrest on the pin when the armrest is pivoted in one direction. There is also provided a cam ring selectively movable with the armrest for rotational engagement with the gear. The cam ring has an exterior cam surface that contacts a portion of the ratchet and pivots the ratchet clear of engagement with the gear when the armrest is pivoted in another direction. The new armrest incorporates fewer components lowering cost of production, improving torsion force and load bearing capabilities, improving life of the furniture piece and strengthening armrest and furniture piece assembly.