Malfunction diagnosis system
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Solution Overview
Problem
Current failure diagnosis systems for air-conditioning apparatuses have low accuracy during normal operation, leading to frequent unnecessary failure diagnosis operations, increased power consumption, and reduced comfort, due to the preliminary diagnosis being based on limited data and not utilizing data effectively for improved efficiency and accuracy.
Innovation Solution
A failure diagnosis system that includes a state detection unit, a controller, and an abnormality diagnosis unit to detect and diagnose abnormalities in the refrigerant circuit by changing actuator control values and analyzing state and control data before and after the change, enabling accurate identification of abnormality causes during normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If failure diagnosis operation is performed frequently to improve diagnosis accuracy, then diagnosis accuracy is improved, but power consumption increases and comfort is reduced
Solution Approach 1:
The system performs preliminary diagnosis during normal operation using existing state data before executing full failure diagnosis operation. This preliminary assessment identifies cases where failure diagnosis is truly necessary, avoiding unnecessary full diagnosis operations and reducing power consumption while maintaining high diagnosis accuracy through the two-stage approach
2Measurement precision
If actuator control is fixed during failure diagnosis operation to improve diagnosis accuracy, then diagnosis accuracy is improved, but comfort and power consumption are negatively affected
Solution Approach 1:
The system performs preliminary diagnosis during normal operation with actuators operating normally, preserving comfort while gathering initial diagnostic data. Full failure diagnosis operation with fixed actuator control is only executed when the preliminary diagnosis indicates a genuine need, thus minimizing comfort degradation while maintaining high diagnosis accuracy
3Reliability
If preliminary diagnosis is set to be easily determined to improve detection rate, then abnormality detection rate is improved, but false positives increase leading to frequent unnecessary full diagnosis operations
Solution Approach 1:
The diagnosis process is segmented into two stages: preliminary diagnosis that operates with higher sensitivity to catch potential abnormalities, followed by full failure diagnosis operation that provides precise confirmation. This segmentation allows the system to cast a wide net initially while maintaining high diagnostic precision through the second stage, reducing false positives from triggering unnecessary full diagnosis operations
4Productivity
If data from preliminary diagnosis is not utilized to improve efficiency, then diagnostic process is simple, but diagnostic efficiency and accuracy cannot be increased
Solution Approach 1:
The system implements feedback by utilizing state data and diagnosis results from the preliminary diagnosis to inform and guide the full failure diagnosis operation. This feedback mechanism allows the system to leverage previously collected data, improving diagnostic efficiency by avoiding redundant measurements and enhancing accuracy by comparing results across both diagnosis stages
Data Source
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AI summary
Provided is a failure diagnosis system that diagnoses the state of an air-conditioning apparatus having a refrigerant circuit in which refrigerant circulates. The failure diagnosis system has an abnormality diagnosis unit that performs normal-operation abnormality diagnosis for determining whether or not there is an abnormality in the air-conditioning apparatus by using state data and control data during normal operation of the air-conditioning apparatus. If the abnormality diagnosis unit determines that there is an abnormality in the air-conditioning apparatus, the abnormality diagnosis unit changes a control value for an actuator of the air-conditioning apparatus and acquires state data and control data. Then, the abnormality diagnosis unit performs abnormality-cause identification diagnosis for identifying the cause of the abnormality in the air-conditioning apparatus by using the state data and the control data acquired before the change of the control value and the state data and the control data acquired after the change of the control value.