Air conditioner

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Solution Overview

Problem

The refrigerant gas sensor in air conditioners is prone to erroneously detecting external gases like propane or pesticide as refrigerant gas due to its upward-facing opening, leading to incorrect recognition and potential malfunctions.

Innovation Solution

The air conditioner incorporates a refrigerant gas sensor with a cylindrical casing member fixed to the lower surface of a printed board, featuring a first opening below the detecting element to introduce gas, which reduces the likelihood of detecting small amounts of external gases and prevents water or dust attachment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the refrigerant gas sensor opening faces upward to detect leaked refrigerant gas, then the detection coverage is improved, but different gases from outside are erroneously recognized as refrigerant gas

Engineering Contradiction:
Improvedetection accuracyVSAvoidfalse detection rate
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent inverts the conventional upward-facing opening design by positioning the opening at the lower part of the sensor housing, facing downward. This inversion exploits the density difference between refrigerant gas (heavier than air) and ambient gases, allowing the sensor to selectively detect refrigerant gas that settles at lower positions while excluding lighter ambient gases from false detection

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

Solution Approach 2:

The patent applies local quality by creating a differentiated gas detection environment: the lower opening position creates a localized detection zone where only dense refrigerant gas can enter, while the upper portion remains excluded from detection. This spatial differentiation of detection quality based on gas density resolves the contradiction between comprehensive detection and false positive prevention

Inventive Principle:
Principle #3Local quality

2Measurement precision

If the sensor opening faces upward to maximize gas intake, then the detection sensitivity is improved, but water or dust attaches to the sensor causing contamination

Engineering Contradiction:
Improvedetection sensitivityVSAvoidsensor contamination
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent inverts the opening orientation from upward to downward facing. This inversion prevents water and dust particles, which naturally settle or fall downward due to gravity, from entering the sensor opening, thereby protecting the sensor from contamination while maintaining detection sensitivity through the lower position where refrigerant gas accumulates

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

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 effectively prevents external gases from being misidentified as refrigerant gas, enhancing detection accuracy and protecting the sensor from contamination by external substances.

Implementation Method 1

a detecting element configured to detect leakage of refrigerant gas

Methodology Applied
Scientific EffectGas detection:

Implementation Method 2

a first opening through which the refrigerant gas is introduced into an inside of the casing member, and the first opening being below the detecting element

Methodology Applied
Scientific EffectGas flow introduction:

Data Source

PatentEP3214383B1Air conditioner
Publication Date: 2020.01.15 DAIKIN INDUSTRIES LTD
  • EP3214383B1 patent drawingFigure 1
  • EP3214383B1 patent drawingFigure 2
  • EP3214383B1 patent drawingFigure 3

AI summary

A refrigerant gas sensor is typically attached so that an opening for introducing leaked refrigerant gas into the inside faces upward. With this arrangement, however, a small amount of a different gas such as propane and pesticide, which is sucked from the outside of an air conditioner, may be erroneously recognized as refrigerant gas. On this account, a refrigerant gas sensor 9 includes a detecting element 61 for detecting leakage of refrigerant gas and a casing member 62 provided to surround the detecting element 61. The casing member 62 has a casing opening (first opening) 62a through which the refrigerant gas is introduced into the inside of the casing member 62. The casing opening (first opening) 62a is below the detecting element 61.