Support Arm Overpressure Cooling for Hand-Held Cut-Off Tools

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Solution Overview

Problem

Hand-held work tools for cutting concrete and stone face challenges with heat management and vibration, leading to operator discomfort and potential tool damage.

Innovation Solution

The hand-held work tool incorporates a fan to generate a flow of cooling air, which increases air pressure inside the tool, reducing dust and debris entry, and includes a vibration isolation system to minimize operator exposure to vibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a fan is used to cool the electric motor, then the motor cooling efficiency is improved, but the complexity of the tool increases

Engineering Contradiction:
Improvemotor temperatureVSAvoidtool complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The fan is integrated into the motor assembly such that the fan is driven directly by the motor's rotational axis. This merging of the fan and motor into a single integrated unit achieves effective motor cooling while minimizing the increase in overall tool complexity, as the fan shares the motor's drive mechanism rather than requiring a separate power source.

Inventive Principle:
Principle #5Merging (Combining)

2Object-affected harmful factors

If the interior space is sealed to protect components, then protection against dust and debris is improved, but heat dissipation deteriorates

Engineering Contradiction:
Improvedust and debris entryVSAvoidheat dissipation
Core Design Contradiction:
Object-affected harmful factorsVSTemperature

Solution Approach 1:

The belt guard is designed with selective openings at specific locations - the first opening allows cooling air to enter the interior space near the motor, while the second opening allows hot air to exit. This localized placement of openings provides different functions (cooling air intake and hot air exhaust) at different positions, achieving both dust protection through selective sealing and effective heat dissipation through strategic ventilation paths.

Inventive Principle:
Principle #3Local quality

3Strength

If the belt guard is made robust to protect internal components, then component protection is improved, but the tool weight increases

Engineering Contradiction:
Improvebelt guard strengthVSAvoidtool weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The belt guard is constructed from a composite material that combines plastic and metal elements. The plastic portions provide corrosion resistance and basic structural form, while strategic metal reinforcements are added only where required for strength and rigidity. This composite approach achieves the necessary robustness for component protection while minimizing overall weight compared to a fully metal construction.

Inventive Principle:
Principle #40Composite materials

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 solution effectively cools the electric motor and battery, reducing the risk of overheating and prolonging tool life, while also minimizing vibration, enhancing operator comfort and tool durability.

Implementation Method 1

The hand-held work tool comprises a fan, configured to generate a flow of cooling air

Methodology Applied
Scientific EffectForced Convection: Forced Convection

Implementation Method 2

a portion of the flow of cooling air is arranged to be guided via at least one opening into the interior space, thereby increasing an air pressure in the interior space above an ambient air pressure level

Methodology Applied
Scientific EffectPressure Gradient: Pressure Gradient

Data Source

PatentEP4065327B1A hand-held electrically powered work tool creating an overpressure in the interior space of the support arm
Publication Date: 2025.06.04 HUSQVARNA AB
  • EP4065327B1 patent drawingFigure 1~2A
  • EP4065327B1 patent drawingFigure 2B~2C
  • EP4065327B1 patent drawingFigure 3A~3B

AI summary

A handheld work tool comprising a cutting tool (130), an electric motor (140) having a rotational axis and being arranged to drive the cutting tool (130), a battery compartment (150) for a battery (220) arranged to power the electric motor (140), a support arm (240) and a belt guard (115). The support arm (240) is arranged to support the circular cutting tool (130) on a first end (241) of the support arm, and to support the electric motor (140) at a second end of the support arm (242), opposite to the first end (241). The belt guard (115) and at least a part of the support arm (240) are configured to enclose an interior space (340), where the hand-held work tool (100, 200, 800, 1000) comprises a fan (145), configured to generate a flow of cooling air. A portion of the flow of cooling air is arranged to be guided via at least one opening (310) into the interior space (340), thereby increasing an air pressure in the interior space (340) above an ambient air pressure level.