Vibration-Isolated Fuel Injector Assembly for Handheld Power Tools

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Solution Overview

Problem

Conventional fuel injection systems in hand-held power tools, such as power cutters and chain saws, face issues with high temperatures and vibrations near the fuel injector, leading to vapor lock and damage to electrical components, while traditional solutions like active cooling are ineffective when the machine is turned off.

Innovation Solution

The fuel injector is positioned in a vibrationally decoupled second mass, separated from the combustion engine by resilient members, with a non-rigid conduit connecting it to the combustion engine, and integrated with a throttle valve and ECU in a compact module, allowing for reduced temperature and vibration exposure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the fuel injector is mounted close to the combustion engine, then the fuel delivery response is improved, but the fuel injector is exposed to high temperatures and vibrations causing vapor lock and component damage

Engineering Contradiction:

Improvefuel delivery responseVSAvoidtemperature and vibration exposure

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The fuel injection system is segmented into separate functional modules: the fuel injector is mounted on the combustion engine while the fuel pump is mounted on the vibrationally decoupled mass. This segmentation allows each component to be positioned optimally - the injector close to the combustion chamber for rapid response, while the pump is protected from vibrations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A flexible fuel line acts as an intermediary connection between the fuel pump on the vibrationally decoupled mass and the fuel injector on the combustion engine. This flexible conduit transmits fuel while accommodating the spatial separation and vibration isolation requirements.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If the fuel injector is mounted directly on the crankcase, then the assembly is simplified, but the electrical components are exposed to vibrations causing damage

Engineering Contradiction:

Improveassembly complexityVSAvoidelectrical component reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The system is divided into two separate mounting locations: the fuel injector remains on the combustion engine for simplicity, while the fuel pump is mounted on the vibrationally decoupled mass. This segmentation protects the electrical components of the pump from vibrations while maintaining assembly simplicity through modular design.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The fuel pump is extracted from the vibrating crankcase area and mounted on the vibrationally decoupled mass. This extraction removes the electrical components from the harmful vibration environment while maintaining the fuel injection function through the flexible fuel line connection.

Inventive Principle:

Principle #2Taking out (Extraction)

3Temperature

If active cooling is used for the fuel injector, then the temperature control is improved, but the system becomes ineffective when the machine is turned off

Engineering Contradiction:

Improvefuel injector temperature controlVSAvoidtemperature control adaptability

Core Design Contradiction:

TemperatureVSAdaptability or versatility

Solution Approach 1:

A heat sink acts as a thermal intermediary between the fuel injector and the surrounding environment. The heat sink passively dissipates heat from the injector through its thermal mass and surface area, providing temperature control without requiring active cooling systems that would be ineffective when the machine is off.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

This configuration reduces fuel injector temperature and vibration, preventing vapor lock and protecting electrical components, while enabling a modular and efficient assembly of the fuel system, enhancing performance and reliability.

Implementation Method 1

a second mass of the equipment is vibrationally decoupled from the first mass by means of one or more resilient members

Methodology Applied

Scientific EffectVibration isolation: Damping

Implementation Method 2

The air and fuel intake flow of the combustion engine optionally passes from the second mass to the first mass via a non-rigid tubular conduit. This non-rigid conduit does not forward much vibration from the first mass to the second mass

Methodology Applied

Scientific EffectVibration isolation: Damping

Data Source

PatentUS20250327433A1A fuel injection arrangement for hand-held powertools

Publication Date: 2025.10.23 HUSQVARNA AB

AI summary

Handheld construction equipment may include a crankcase scavenged combustion engine arranged to drive a work tool where a fuel injector is configured to provide a controlled amount of fuel into an air and fuel intake flow of the combustion engine, and where an idling air flow channel is arranged to connect with the air and fuel intake flow of the combustion engine in connection to the fuel injector.