Flow Rate Sensor Diagnosis Under Pressure and Temperature Variation
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Solution Overview
Problem
Existing diagnostic systems for flow rate sensors face inaccuracies due to changes in measurement ambient conditions, such as pressure and temperature, leading to errors in volume value calculations and misdiagnosis.
Innovation Solution
A diagnostic system that measures and corrects output-related values and reference values based on measurement ambient conditions, using existing sensors to improve diagnostic accuracy without the need for additional sensors, and includes a flow rate adjustment mechanism to shorten depressurization time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the flow path is depressurized and the volume value is calculated using the output-related value, then the flow rate sensor can be diagnosed, but measurement ambient condition changes (pressure and temperature) cause errors in the volume value calculation leading to inaccurate diagnosis
Solution Approach 1:
The patent applies parameter changes by correcting the output-related value based on measured pressure and temperature deviations from reference values. The correction formula adjusts the output-related value using the ratio of reference to actual pressure and temperature parameters, compensating for ambient condition changes and maintaining accurate volume value calculations despite environmental variations.
2Measurement precision
If additional sensors are used to measure ambient conditions for correction, then diagnostic accuracy improves, but device complexity and cost increase
Solution Approach 1:
The patent applies universality by making the existing pressure and temperature sensors serve dual purposes: their primary function for flow rate measurement and an additional function for diagnosing sensor abnormalities. By utilizing these existing sensors for both measurement and self-diagnosis, the system avoids adding dedicated diagnostic sensors, thereby reducing device complexity while maintaining high diagnostic accuracy.
3Measurement precision
If the depressurization time is extended to obtain accurate pressure change data, then the volume value calculation becomes more accurate, but the diagnostic time increases
Solution Approach 1:
The patent applies preliminary action by pre-storing reference pressure and temperature values obtained under known normal conditions. These reference values are prepared in advance and used for comparison during actual diagnosis, eliminating the need to perform lengthy depressurization tests to establish baseline data. This allows rapid diagnosis while maintaining accuracy through comparison with pre-established reference data.
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
The system provides accurate diagnosis of flow rate sensors by accounting for ambient condition changes, reducing the likelihood of misdiagnosis and improving diagnostic precision.
Implementation Method 1
a mass flow rate Q is calculated from the differential pressure between pressures P1 and P2 measured by both the pressure sensors
Implementation Method 2
the temperature measured by the temperature sensor and considered constant here
Data Source
AI summary
The present invention intends to more accurately diagnose a function of a flow rate sensor regardless of a variation in measurement ambient condition. The present invention includes: a flow rate sensor for measuring the flow rate of fluid; a correction part adapted to measure an output value of the flow rate sensor or a value related to the output value (hereinafter collectively referred to as an “output-related value”), relates the measured output-related value and a corresponding measurement ambient condition to each other, and in accordance with the measurement ambient condition in measurement data, correct the output-related value or a reference value that is predetermined in order to determine whether the output-related value is normal; and a diagnostic part adapted to compare the output-related value and the reference value on the basis of a correction result by the correction part and correct the function of the flow rate sensor.