Outdoor Unit Electrical Box Layout for Flammable Refrigerant Safety

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Solution Overview

Problem

Conventional air-conditioning systems using flammable refrigerants with low global warming potential face safety concerns due to refrigerant leakage into electrical components, and existing solutions like non-contact switches and gas-permeable films are costly and unreliable, requiring frequent maintenance.

Innovation Solution

The outdoor unit design positions the electrical component box and controller above one-third of the housing height, preventing refrigerant entry and using wide bandgap semiconductors for improved heat resistance and safety, eliminating the need for costly gas-permeable films and enhancing reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If non-contact switches or gas-permeable films are used to prevent refrigerant leakage into electrical components, then safety is improved, but cost increases significantly and reliability decreases due to frequent maintenance

Engineering Contradiction:
ImprovesafetyVSAvoidcost and maintenance
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the electrical component box from the refrigerant-containing environment by providing a separate enclosed space with a dedicated access door. This physical separation eliminates the need for gas-permeable films or non-contact switches, as the electrical components are completely isolated from refrigerant leakage zones while maintaining cost-effectiveness and reliability.

Inventive Principle:
Principle #2Taking out (Extraction)

2Device complexity

If electrical components are exposed to flammable refrigerant, then device complexity is reduced, but safety deteriorates due to fire hazard

Engineering Contradiction:
ImprovestructureVSAvoidfire hazard
Core Design Contradiction:
Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent segments the outdoor unit into distinct functional zones: a refrigerant circulation zone and an electrical component zone. The electrical component box is separated from the refrigerant environment, creating physical barriers that prevent fire hazards while maintaining structural simplicity and avoiding complex protective measures.

Inventive Principle:
Principle #1Segmentation

3Ease of manufacture

If conventional electrical component placement is used, then ease of manufacture is improved, but safety deteriorates due to refrigerant entry into electrical components

Engineering Contradiction:
Improvecomponent placementVSAvoidsafety
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies local quality by providing enhanced protection specifically for the electrical component box through separate enclosure and dedicated access door, while the rest of the outdoor unit maintains conventional simple structure. This localized approach ensures safety for electrical components without complicating the overall manufacturing process.

Inventive Principle:
Principle #3Local quality

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 significantly enhances safety by preventing refrigerant exposure to electrical components while reducing costs and maintenance, ensuring long-term reliability and efficient operation.

Implementation Method 1

an outdoor air-sending device disposed on a top of the housing and configured to form an air flow inside the housing

Methodology Applied
Scientific EffectAir flow: Convection

Implementation Method 2

a heat-source-side heat exchanger disposed along a part of an inner wall of the housing, and into which the refrigerant discharged from the compressor or the refrigerant that is to be suctioned into the compressor flows

Methodology Applied
Scientific EffectHeat transfer: Heat Exchanger

Data Source

PatentEP2833073B1Outdoor unit and air conditioning device with outdoor unit
Publication Date: 2020.05.06 MITSUBISHI ELECTRIC CORP
  • EP2833073B1 patent drawingFigure 1
  • EP2833073B1 patent drawingFigure 2
  • EP2833073B1 patent drawingFigure 3

AI summary

In an outdoor unit 10, an electrical component box 30 is disposed such that a bottom surface E1 of the electrical component box 30 is located at a height greater than 1/3 a height h1 of a housing 10 from a bottom surface E2 of the housing 10. A controller 50 and relays 33a through 33d are disposed such that bottom surfaces E4 and E5 thereof are located at a height greater than 1/3 a height h2 of the electrical component box 30 from a bottom surface E3 of the electrical component box 30.