Multi-Method Refrigerant Leakage Detection for Reduced False Positives

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Solution Overview

Problem

Conventional refrigerant leakage detection methods based on a single approach, such as subcooling of a condenser, are prone to errors due to variations in aging and operating conditions, leading to insufficient detection accuracy.

Innovation Solution

A refrigerant leakage detection system that employs multiple methods, including short-term and long-term operational state analysis, with a first control unit determining leakage based on a first period and a second control unit using a second method on a second, longer period, and a third unit confirming leakage only when both methods agree, thereby enhancing accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single method is used to detect refrigerant leakage, then the device complexity is reduced, but the detection accuracy deteriorates due to erroneous detection from aging and operating condition variations

Engineering Contradiction:
Improvedetection system complexityVSAvoidrefrigerant leakage detection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent combines multiple detection methods (subcooling degree method and discharge temperature method) into a single detection system. The control unit performs both detection methods simultaneously and integrates their results, allowing the system to maintain low complexity while achieving high detection accuracy through method combination.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The system uses feedback by continuously monitoring operational parameters (subcooling degree, discharge temperature) and comparing them against threshold values. The control unit adjusts detection decisions based on feedback from multiple measurement channels, improving accuracy while maintaining system simplicity through intelligent integration logic.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If multiple detection methods are used to improve detection accuracy, then the detection accuracy is improved, but the device complexity increases

Engineering Contradiction:
Improverefrigerant leakage detection accuracyVSAvoiddetection system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges multiple detection methods (subcooling degree detection and discharge temperature detection) into a unified detection system. The control unit integrates both methods and uses logical combination of their results, achieving high detection accuracy while preventing excessive complexity increase through unified control architecture.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The control unit is designed with multi-functionality to perform both subcooling degree calculation and discharge temperature monitoring using the same hardware resources. This universal approach allows multiple detection methods to be implemented without proportionally increasing device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Speed

If detection is based on short-term operational state, then the responsiveness is improved, but the detection accuracy deteriorates due to transient conditions

Engineering Contradiction:
Improvedetection responsivenessVSAvoidrefrigerant leakage detection accuracy
Core Design Contradiction:
SpeedVSMeasurement precision

Solution Approach 1:

The patent combines short-term detection (for responsiveness) with long-term detection (for accuracy) by merging their results. The control unit performs both detection timeframes simultaneously and integrates their outcomes, achieving both fast responsiveness and high accuracy without sacrificing either attribute.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The system implements periodic detection at different time scales - short-term periodic monitoring for immediate detection and long-term periodic analysis for trend confirmation. This multi-periodic approach maintains responsiveness while filtering out transient false positives through periodic verification.

Inventive Principle:
Principle #19Periodic action

4Measurement precision

If detection is based on long-term operational state, then the detection accuracy is improved, but the responsiveness deteriorates

Engineering Contradiction:
Improverefrigerant leakage detection accuracyVSAvoiddetection responsiveness
Core Design Contradiction:
Measurement precisionVSSpeed

Solution Approach 1:

The patent merges long-term detection results (for accuracy) with short-term detection results (for responsiveness). The control unit combines both timeframes' detection outcomes, achieving high accuracy from long-term data while maintaining fast responsiveness through short-term monitoring integration.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The system performs preliminary long-term operational state analysis to establish baseline accuracy, then uses this preliminary information to enhance the responsiveness of subsequent detections. The long-term data serves as preliminary action that improves the speed and accuracy of ongoing detection processes.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4343235B1Refrigerant leakage detection system
Publication Date: 2025.12.03 DAIKIN INDUSTRIES LTD
  • EP4343235B1 patent drawingFigure 1
  • EP4343235B1 patent drawingFigure 2
  • EP4343235B1 patent drawingFigure 3

AI summary

If refrigerant leakage is detected by only one method, the detection accuracy is not sufficient. A refrigerant leakage detection system (1) is a system for a refrigeration cycle device (100) having a refrigerant circuit (11). The refrigerant leakage detection system (1) includes a first control unit (10), a second control unit (20), and a third control unit (30). The first control unit (10) uses a first method to determine the presence or absence of refrigerant leakage from the refrigerant circuit (11). The second control unit (20) uses a second method different from the first method to determine the presence or absence of refrigerant leakage from the refrigerant circuit (11). The third control unit (30) determines the presence or absence of refrigerant leakage from the refrigerant circuit (11) on the basis of the determination result of the first control unit (10) and the determination result of the second control unit (20). The third control unit (30) determines that there is a refrigerant leakage in the refrigerant circuit (11) if the first control unit (10) determines that there is a refrigerant leakage from the refrigerant circuit (11) and the second control unit (20) determines that there is a refrigerant leakage from the refrigerant circuit (11).