Flow Sensor Error Detection via Temperature Ratio Comparison
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Mass flow sensors face challenges in detecting errors due to contamination and sensor drift, especially when defined mass flows are not easily specified during operation, making it difficult to check the plausibility of sensor signals effectively.
Innovation Solution
The method involves recording temperature data from two temperature sensors under reference conditions with varying mass flows, calculating and saving reference values for mass flow and temperature quotients, and comparing these values during normal operation to detect any significant deviations that indicate errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heating element is switched off for plausibility checking without flow, then the temperature sensors can be checked, but it is not possible to determine drift over a wide working range
Solution Approach 1:
The patent applies preliminary action by performing sensor checks under multiple predefined reference conditions (different mass flows and temperatures) before actual operation. Reference values for temperature ratios are stored in advance for various operating points, enabling the sensor to be checked across its entire working range during normal operation without requiring shutdown or flow cessation.
2Productivity
If defined mass flows are not specified during operation, then normal sensor operation continues, but sensor signal plausibility cannot be checked
Solution Approach 1:
The patent implements feedback by continuously comparing the actual temperature ratio measured during operation with pre-stored reference values corresponding to the current mass flow condition. This feedback mechanism enables plausibility checking without interrupting normal sensor operation, as the system automatically determines whether measured values deviate from expected reference behavior.
Solution Approach 2:
The patent uses the temperature ratio as an intermediary parameter to enable plausibility checking. Instead of directly measuring mass flow or requiring external reference flows, the system uses the ratio of temperatures at two different points as a mediator that can be compared against reference values, allowing indirect verification of sensor signal validity during continuous operation.
3Measurement precision
If chemical reactions and contamination occur, then sensor signal changes, but error detection is difficult without reference comparisons
Solution Approach 1:
The patent applies parameter changes by utilizing the temperature ratio parameter instead of absolute temperature values for error detection. By comparing ratios under different operating conditions and against stored reference ratios, the system can detect contamination and drift effects that would be difficult to identify using single-point measurements, thereby improving error detection capability while maintaining measurement precision.
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 approach allows for the detection of errors in mass flow sensors during normal operation, enabling early identification of contamination or sensor component issues, thereby ensuring accurate mass flow measurement and preventing sensor drift over a wide working range.
Implementation Method 1
the heat conduction from the heater to the two temperature sensors can be improved or worsened
Implementation Method 2
The mass flow then flows past the second temperature sensor, which detects the temperature T2. Because of the heat input Q̇ the temperature T2 detected by means of the second temperature sensor 4 is higher than the temperature T1 detected by means of the first temperature sensor 3
Data Source
Figure 1~2
Figure 3~4
AI summary
The method involves measuring the quotient of the temperature under reference condition by two temperature sensors (3,4), where the measurement depending on one of the two determined temperatures or the determined mass flow (m), and stored in a memory. The quotient of the temperature is measured by both the temperature sensors, and from which the mass flow is determined in normal operation. The actual measured quotient differs from the stored quotients at the same mass flow from the corresponding reference measurement that is more than a predetermined tolerance.