Cutting Tool Gear Mechanism Variable Mechanical Advantage

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Solution Overview

Problem

Existing hedge clippers lack a user-friendly and safe mechanism to selectively change mechanical advantage for varying cutting applications, requiring multiple tools and posing safety concerns during different cutting tasks.

Innovation Solution

A cutting tool with a gear mechanism and an adjustment mechanism, such as a screw or toggle switch, that allows users to change mechanical advantage by aligning protrusions with cut-out portions, providing different modes of operation through simple and safe locking mechanisms, and incorporating a spring buffer for enhanced safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a gear mechanism is integrated with cutting blades to provide variable mechanical advantage, then cutting capability for different branch sizes is improved, but safety and ease of operation deteriorate due to complex locking mechanisms

Engineering Contradiction:
Improvecutting capability for different branch sizesVSAvoidoperation safety and convenience
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The gear mechanism is segmented into discrete gear positions (first gear position and second gear position) with distinct mechanical advantage ratios. Each position is independently lockable through the locking mechanism, allowing users to select appropriate gear ratios for different cutting tasks without dealing with continuous adjustment complexity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The locking mechanism is designed to automatically lock the gear lever at predetermined gear positions when engaged. This preliminary positioning action ensures that the gear mechanism settles into stable, pre-determined configurations before cutting operations begin, eliminating the need for users to manually balance or fine-tune gear positions during operation

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If multiple cutting tools are used to cater to different cutting applications, then cutting versatility is improved, but device complexity and user burden increase

Engineering Contradiction:
Improvecutting application coverageVSAvoidnumber of tools required
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The cutting tool integrates multiple functions by incorporating a gear mechanism with at least two gear positions that provide different mechanical advantage ratios. The first gear position offers a first mechanical advantage ratio for certain cutting applications, while the second gear position offers a second mechanical advantage ratio for other applications, allowing a single tool to replace multiple specialized cutting tools

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The cutting tool transitions from a static mechanical advantage configuration to a dynamic one through the gear mechanism. The gear lever can be shifted between first and second gear positions, allowing the mechanical advantage ratio to change dynamically based on cutting requirements. This dynamic adjustment capability enables one tool to adapt to various cutting tasks that previously required multiple fixed-tools

Inventive Principle:
Principle #15Dynamics

3Reliability

If a locking mechanism is added to securely lock gear positions, then operational safety is improved, but device complexity increases

Engineering Contradiction:
Improvegear position stabilityVSAvoidmechanism component count
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The locking mechanism is merged with the gear lever assembly, where the gear lever itself incorporates or is integrated with the locking function. This combination eliminates the need for completely separate locking components and reduces overall mechanism complexity while maintaining secure gear position locking

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The locking mechanism is designed to automatically engage and lock the gear lever at predetermined positions when the gear shifter is moved. The mechanism self-activates based on the gear lever's position, eliminating the need for separate manual locking actions or complex control systems. The gear lever's own movement triggers the locking action, simplifying the overall system

Inventive Principle:
Principle #25Self-service

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

Enables easy and safe operation with variable mechanical advantage, allowing for efficient cutting of branches of different sizes without compromising safety or ergonomics, by allowing users to switch between dynamic and powerful cutting modes with intuitive mechanisms.

Implementation Method 1

a gear mechanism integrated with cutting blades of the hedge clipper to allow some respite

Methodology Applied
Scientific EffectGear mechanism: Gear

Implementation Method 2

change mechanical advantage between the first lever and the second lever

Methodology Applied
Scientific EffectMechanical advantage: Mechanical Advantage

Implementation Method 3

incorporating a spring buffer for enhanced safety

Methodology Applied
Scientific EffectSpring buffer: Spring

Data Source

PatentEP3879965B1Cutting tool
Publication Date: 2022.09.28 HUSQVARNA AB
  • EP3879965B1 patent drawingFigure 1
  • EP3879965B1 patent drawingFigure 2
  • EP3879965B1 patent drawingFigure 3

AI summary

A cutting tool (100) includes a first lever (110) having a first cutting blade (114). Further, the cutting tool (100) includes a gear portion (116) associated with the first cutting blade (114). The cutting tool (100) includes a second cutting blade (124) pivotally coupled to the first lever (110). The cutting tool (100) includes a gear lever (130) pivotally coupled to the second cutting blade (124) and the second handle portion (122). The cutting tool (100) is characterized in that the second lever (120) includes a first cut-out portion (202). The gear lever (130) includes a second cut-out portion (204). Further, the adjustment mechanism (140, 500) includes at least one protrusion (210, 506) to selectively abut with any of the first cut-out portion (202) and the second cut-out portion (204). The cutting tool (100) includes a selection mechanism (142, 502) to selectively align the at least one protrusion (210, 506).