Hydrogen Flowmeter Failure Diagnosis Using Tank PVT Comparison
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Solution Overview
Problem
The accuracy of flowmeters in hydrogen filling devices for fuel cell vehicles is difficult to verify continuously due to the need for large-scale measurement devices, making it challenging to detect temporal or secular changes in measurement accuracy.
Innovation Solution
A method that measures hydrogen gas filling amounts using a flowmeter, calculates filling amounts based on tank pressure, temperature, and volume, and compares these values with past performance data to determine if the flowmeter has failed, outputting an alarm if errors exceed predetermined limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gravimetric method with large-scale measurement device is used for calibration, then measurement accuracy verification is achieved, but device complexity and operational difficulty increase significantly
Solution Approach 1:
The patent creates a virtual copy of the gravimetric calibration method by using PVT (Pressure-Volume-Temperature) calculation based on ideal gas law. Instead of physically weighing hydrogen gas with large-scale measurement devices, the system calculates the expected filling amount based on tank pressure, volume, and temperature data, then compares this calculated value with the flowmeter measurement. This virtual copying approach maintains measurement accuracy verification while eliminating the need for complex physical calibration equipment.
Solution Approach 2:
The patent replaces the mechanical gravimetric measurement system (physical weighing scales and large measurement devices) with a computational PVT-based system. By substituting mechanical measurement with mathematical calculation based on gas laws, the system achieves the same verification purpose without the complexity and operational burden of physical calibration equipment.
2Measurement precision
If gravimetric calibration is performed only at startup, then initial accuracy is confirmed, but temporal changes in flowmeter accuracy cannot be detected
Solution Approach 1:
The patent transforms the calibration process from a discrete startup-only event to a continuous operational verification. The PVT-based calculation method can be executed repeatedly during normal filling operations without interrupting service, allowing continuous monitoring of flowmeter accuracy. Each filling operation generates new data points for comparison, enabling detection of temporal drift in measurement accuracy throughout the device's operational life.
Solution Approach 2:
The system implements feedback by continuously comparing the flowmeter measurement with the PVT-calculated filling amount and monitoring the error trend over time. When the error exceeds predetermined thresholds or shows significant temporal变化, the system can trigger alerts or adjustments, creating a closed-loop verification system that maintains reliability through ongoing monitoring rather than single-point calibration.
3Reliability
If frequent calibration is performed to detect temporal changes, then accuracy verification improves, but operational time and resource consumption increase
Solution Approach 1:
The PVT-based verification method is integrated into normal filling operations, allowing accuracy checks to occur continuously without stopping the hydrogen filling device. Unlike traditional gravimetric calibration that requires dedicated calibration time and equipment setup, this method uses routine operational data (pressure, volume, temperature readings during filling) to perform verification, eliminating time loss while maintaining frequent monitoring capability.
Data Source
AI summary
According to one aspect of the present invention, a method for diagnosing a failure of a flowmeter in a measuring machine, includes calculating a filling amount at an end of filling of the hydrogen gas into a tank from the measuring machine by using a pressure, a temperature, and a volume of the tank; and determining whether or not the flowmeter fails by using a plurality of error values between a metering filling amount at the end of filling measured using the flowmeter and a calculated filling amount at the end of filling calculated using the pressure, the temperature, and the volume of the tank, the plurality of error values being based on a plurality of past performance data stored in a storage device, and an error value at the end of filling of the hydrogen gas at a present time, and outputting a result.