Flow Sensing Device Temperature Compensation Lookup Table
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Solution Overview
Problem
Differential pressure measurement devices face inaccuracies in measuring low flow rates due to thermal drift, leading to poor resolution and potential discomfort for patients undergoing CPAP therapy, as the existing systems struggle to accurately determine exhalation and provide pressure relief.
Innovation Solution
A flow sensing device with a temperature coefficient pre-calibrated for accurate flow measurement, incorporating a differential pressure sensor, temperature sensor, and processor to correct for thermal drift, using pulse width modulation and amplification to enhance signal resolution and accuracy across varying flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If differential pressure measurement devices are used to measure flow rate, then flow measurement can be obtained, but thermal drift causes inaccurate measurements especially at low flow rates
Solution Approach 1:
The patent applies parameter changes by introducing temperature compensation through a lookup table that stores corrected flow rate values corresponding to different temperature conditions. The system retrieves the appropriate flow rate value from the lookup table based on the measured temperature, thereby compensating for thermal drift effects and improving measurement accuracy across varying temperature conditions.
2Reliability
If differential pressure measurement devices are used to determine exhalation timing, then pressure relief can be delivered, but thermal drift leads to poor resolution and timing inaccuracies
Solution Approach 1:
The patent uses parameter changes by implementing temperature-dependent flow rate correction through a lookup table. The system adjusts the flow rate values based on temperature conditions, which improves the resolution and accuracy of exhalation detection timing, thereby enhancing the reliability of pressure relief delivery.
3Measurement precision
If temperature compensation is implemented using a lookup table, then flow rate measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing temperature-compensated flow rate values in a lookup table during device initialization or calibration. This preliminary preparation eliminates the need for complex real-time temperature compensation calculations during actual operation, thereby improving measurement accuracy while minimizing the complexity of the active compensation system.
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 solution provides improved accuracy in measuring low flow rates, reducing thermal drift errors and enhancing the delivery of pressure relief in CPAP therapy, ensuring more precise respiratory flow monitoring and patient comfort.
Implementation Method 1
a differential pressure sensor configured to generate a differential pressure signal responsive to the differential pressure within the flow path
Implementation Method 2
a temperature sensor configured to sense a temperature at or near the differential pressure sensor
Implementation Method 3
a differential amplifier that amplifies differential pressure signals from the differential pressure sensor
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A device (12) that uses a temperature coefficient pre-calibrated for the device for measuring a flow within the device. The device includes a differential pressure sensor (80) configured to generate a differential pressure signal responsive to a differential pressure within a flow path (16) and a temperature sensor configured to sense a temperature near the differential pressure sensor. A differential amplifier amplifies differential pressure signals from the differential pressure sensor. A processor receives signals from the differential pressure sensor, amplified signals from the differential amplifier, and signals from the temperature sensor. The amplified signals are corrected based upon at least a predetermined temperature coefficient, and the processor calculates a flow rate based on the corrected representation of the differential pressure.