Vegetation Cutting Tool Crank Linkage Mechanism
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Solution Overview
Problem
Existing powered vegetation cutting tools face challenges in delivering sufficient torsion force for cutting thicker branches due to overhung loads and continuous operation, making them unsuitable for pruning tools that require a single cutting operation with higher torsion force.
Innovation Solution
A vegetation cutting tool featuring a reduction gear assembly with a crank drivable by the motor, a linkage mechanism with a tab and slot engagement, and limit switches for non-continuous motor activation, allowing for a high reduction ratio and efficient cutting force distribution, reducing overhung loads and enabling effective cutting of thicker branches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a continuous operation mechanism is used for light duty electric scissors, then the device can perform repeated cutting and opening movements, but it produces overhung loads and insufficient torsion force for thicker branches
Solution Approach 1:
The patent implements periodic action by using a crank mechanism that converts continuous motor rotation into reciprocating linear motion of the cutter member. The crank rotates periodically, causing the cutter to move forward for cutting, then reverse and return to the starting position. This periodic reciprocating motion allows the tool to perform repeated cutting operations while the crank mechanism efficiently transmits high torsion force during each cutting stroke, solving the contradiction between continuous operation capability and sufficient cutting force for thick branches.
2Force
If a reduction gearbox with high reduction ratio is used, then sufficient torsion force is achieved for cutting thicker branches, but the device becomes more complex and larger
Solution Approach 1:
The patent replaces a complex multi-stage reduction gearbox with a simpler crank mechanism that directly converts motor rotation into reciprocating motion. Instead of using multiple gear stages to achieve high reduction ratio, the crank mechanism provides mechanical advantage through its geometry and motion conversion, delivering sufficient torsion force for thick branch cutting while maintaining a compact and simple transmission system with fewer moving parts.
3Force
If additional load-carrying bearings are added to support higher loads, then the structure can handle thicker branches, but the device becomes more expensive and less compact
Solution Approach 1:
The patent extracts and eliminates the need for additional load-carrying bearings by designing a crank mechanism that inherently handles high loads through its mechanical advantage. The crank structure itself, combined with the reciprocating motion, efficiently transmits and manages the forces generated during cutting of thick branches, removing the requirement for extra bearing support structures and maintaining a compact, cost-effective design.
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 tool achieves efficient cutting of branches up to 14mm in diameter with a single battery cell, providing a mechanical advantage and reducing the need for additional load-carrying bearings, while being compact and cost-effective for portable use.
Implementation Method 1
A vegetation cutting tool featuring a reduction gear assembly with a crank drivable by the motor... providing a mechanical advantage and reducing the need for additional load-carrying bearings
Implementation Method 2
A vegetation cutting tool featuring a reduction gear assembly with a crank drivable by the motor... allowing for a high reduction ratio and efficient cutting force distribution
Data Source
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Figure 2
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AI summary
The present invention relates to a vegetation cutting tool (10). In particular, the present invention relates to a powered vegetation cutting tool and more particularly to a linkage mechanism for a powered vegetation cutting tool. We describe a vegetation cuffing tool comprising a cutting head (14), a motor (24) and transmission means (25) drivable by the motor. The cutting head includes first and second cutter members (15,20) having respective cuffing surfaces (23,54), wherein the first cutter member (15) is pivotably mounted with respect to the second cutter member (20). Additionally, at least the first cuter member (15) is drivable by the transmission means (25) between a first angular position with respect to the second cutter member (20), in which a space is formed between the respective cutting surfaces, and a second angular position with respect to the second cutter member (20), in which the space between the respective cuffing surfaces is closed. The transmission means (25) also comprises an engagement means (40) associated with the first cutter member (15), and a crank (30) drivable between defined first and second angular crank positions corresponding to the first and second angular positions, in which the crank (30) is operatively coupled to the engagement means (40) by a link (34).