Outdoor Refrigerant Pipe Weak Point for Flammable AC Leak Control

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Solution Overview

Problem

Conventional air conditioners do not adequately prevent refrigerant leakage when using flammable refrigerants, especially in enclosed spaces like kitchens where ignition sources are more common, due to insufficient anticorrosion and pressure-resistant designs.

Innovation Solution

The air conditioner design includes an indoor apparatus with a first refrigerant pipe and an outdoor apparatus with a second refrigerant pipe, where the second pipe has a thinner portion than the minimum thickness of the first pipe, ensuring that any leakage occurs outside the room, and the thickness of the thinner portion is sufficient to prevent leakage within the standard use period.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the thickness of the second refrigerant pipe (outdoor pipe) is reduced to enable thinner portion design, then refrigerant leakage is directed outside the room improving safety, but the pipe's strength and corrosion resistance may be compromised

Engineering Contradiction:
Improverefrigerant leakage prevention in roomVSAvoidpipe thickness
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent applies local quality by creating a thinner portion at a specific location in the second refrigerant pipe (outdoor pipe). This localized thickness reduction ensures that if leakage occurs, it happens outside the room rather than in the indoor apparatus, thereby improving safety while maintaining adequate strength in the critical indoor portions of the system.

Inventive Principle:
Principle #3Local quality

2Reliability

If the thickness of the first refrigerant pipe (indoor pipe) is increased to prevent corrosion and leakage, then reliability improves, but the overall device complexity and material usage increase

Engineering Contradiction:
Improverefrigerant leakage prevention in roomVSAvoidpipe thickness variation
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by creating a thinner portion at a specific location in the second refrigerant pipe (outdoor pipe). This localized thickness reduction ensures that if leakage occurs, it happens outside the room rather than in the indoor apparatus, thereby improving safety while maintaining adequate strength in the critical indoor portions of the system.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent inverts the conventional approach by making the outdoor pipe (second refrigerant pipe) thinner at a specific portion rather than uniformly thickening all pipes. This inversion strategically places the potential leakage point outside the room, improving safety while reducing overall material usage and device complexity.

Inventive Principle:
Principle #13The other way round (Inversion)

Data Source

PatentEP3376138B1Air conditioner
Publication Date: 2022.07.27 MITSUBISHI ELECTRIC CORP
  • EP3376138B1 patent drawingFigure 1~2
  • EP3376138B1 patent drawingFigure 3~5
  • EP3376138B1 patent drawingFigure 6~7

AI summary

Provided is an air conditioner which can suppress refrigerant leakage in a room and has a high safety even when using a flammable refrigerant. The air conditioner includes an indoor apparatus (1) placed in a room, and an outdoor apparatus (2) placed in an outside of the room separated from the room by a wall. The indoor apparatus (1) includes a first refrigerant pipe (3) in which a flammable refrigerant flows. The outdoor apparatus (2) includes a second refrigerant pipe (4) which is connected to the first refrigerant pipe (3) and in which the flammable refrigerant flows. The second refrigerant pipe (4) has a portion smaller in thickness than a minimum-thickness portion of the first refrigerant pipe (3).