Blade Attachment Shear Device for Garden Tool Motor Protection

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Solution Overview

Problem

The fixed length of the motor shaft in garden tools limits the accommodation of multiple blades, leading to increased vibration and wear on the motor when a cross-cut blade strikes a hard object, resulting in a shortened motor lifespan.

Innovation Solution

A blade attachment system with a shear device coupled between the blade holder and clamp device, utilizing a softer material to absorb energy and reduce vibration transfer to the motor shaft, allowing for the use of multiple blades without traditional damper constraints.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional damper is used between the blade and motor shaft, then vibration is reduced, but the motor shaft length is insufficient to accommodate multiple blades and the damper

Engineering Contradiction:

Improvemotor lifespanVSAvoidmotor shaft length

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The damper is segmented into two separate components: a first damper portion attached to the motor shaft and a second damper portion attached to the blade holder. These segments are connected through a shearable link, allowing each segment to be independently mounted on the available shaft length while maintaining the damping function.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A shearable link acts as an intermediary element between the first and second damper portions. This link can be sheared under excessive load to protect the motor, while also allowing the two damper portions to be positioned at different locations along the motor shaft, effectively utilizing the available length.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the motor shaft length is fixed to accommodate a damper and single blade, then the blade assembly is secure, but multiple blades cannot be accommodated

Engineering Contradiction:

Improvenumber of bladesVSAvoidblade attachment system complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The blade attachment system is segmented into modular components: blade holders, dampers, shearable links, and clamps. This segmentation allows multiple blade assemblies to be stacked along the motor shaft, with each assembly being independently attachable and removable, thereby enabling multi-blade configurations without requiring a complete redesign of the attachment system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first and second damper portions are designed to be universally applicable to different blade configurations. The same damper components can be used whether one blade, two blades, or multiple blades are installed, as they can be positioned at different locations along the motor shaft to accommodate various blade arrangements.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Strength

If a cross-cut blade strikes a hard object, then cutting performance is maintained, but excessive force is transmitted to the motor

Engineering Contradiction:

Improveblade impact resistanceVSAvoidforce transmitted to motor

Core Design Contradiction:

StrengthVSForce

Solution Approach 1:

The damper system provides beforehand cushioning by being pre-installed between the blade holder and motor shaft. When the blade strikes a hard object, the damper portions and shearable link absorb and dissipate the impact energy through controlled deformation or shearing, cushioning the motor against excessive force before it can cause damage.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The shearable link is designed to fail in a controlled manner under excessive load, converting the harmful impact force into a beneficial protective mechanism. When the link shears, it sacrificially fails to protect the more valuable motor components, transforming a potential harmful event into a protective action that prevents greater damage.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 shear device effectively dampens vibrations from blade impacts, reducing motor wear and extending the lifespan by absorbing energy through deformation or fracture, enabling the use of thicker cross-cut blades without transferring excessive force to the motor.

Implementation Method 1

a shear device coupled between the blade holder and the clamp device... utilizing a softer material to absorb energy and reduce vibration transfer to the motor shaft... absorbing energy through deformation or fracture

Methodology Applied

Scientific EffectDeformation: Deformation

Implementation Method 2

The shear device effectively dampens vibrations from blade impacts, reducing motor wear and extending the lifespan by absorbing energy

Methodology Applied

Scientific EffectVibration: Vibration

Data Source

PatentEP4311419A1Blade attachment for a garden tool

Publication Date: 2024.01.31 TECHTRONIC CORDLESS GP

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AI summary

A blade attachment system for a garden tool including a rotatable output shaft. The blade attachment system includes a blade holder that can be operatively coupled to the output shaft for rotation therewith and that includes a face for engagement by a blade assembly. A clamp device is engageable with the blade assembly to hold the blade assembly on the blade holder, and a shear device is coupled between the blade holder and the clamp device.