Auto-zeroing Absolute Pressure Sensor for Open Conduit Flow Measurement
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Solution Overview
Problem
Measuring fluid flow rate in open conduits is challenging due to variations in conduit slope, roughness, obstructions, and fluid properties, and existing pressure sensors face issues with atmospheric pressure compensation, requiring multiple sensors or maintenance-prone vent tubes.
Innovation Solution
An absolute pressure sensor system that automatically determines atmospheric pressure offset by measuring pressure outside the fluid and compensates for changes when submerged, using a fluid detecting sensor to prevent accidental submersion and eliminate the need for vent tubes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If differential pressure sensors with vent tubes are used to measure atmospheric pressure offset, then atmospheric pressure compensation is achieved, but the device complexity increases and maintenance requirements increase due to vent tube clogging
Solution Approach 1:
The patent extracts the vent tube component entirely from the system by using an absolute pressure sensor that measures atmospheric pressure directly through its sensing element without requiring a physical vent tube to atmospheric pressure. This eliminates the clogging issue while maintaining atmospheric pressure compensation capability.
Solution Approach 2:
The patent introduces a microelectromechanical system (MEMS) pressure sensing element as an intermediary that can sense atmospheric pressure through the housing walls without requiring a direct physical connection or vent tube. This mediator enables pressure measurement while eliminating the problematic vent tube structure.
2Measurement precision
If multiple pressure sensors are used to measure both fluid pressure and atmospheric pressure, then measurement accuracy improves, but the device complexity and cost increase
Solution Approach 1:
The patent makes the absolute pressure sensor universal by enabling it to perform both atmospheric pressure measurement (when exposed to air) and fluid pressure measurement (when submerged) using the same sensing element. This multi-functionality eliminates the need for separate sensors while maintaining measurement accuracy.
Solution Approach 2:
The patent introduces dynamic functionality where the sensor's measurement mode automatically changes based on its environment - measuring atmospheric pressure when above fluid and fluid pressure when submerged. The system dynamically switches between measurement modes using the same hardware, reducing component count while maintaining accuracy.
3Productivity
If the pressure sensor remains continuously submerged to measure fluid pressure, then flow rate measurement is continuous, but atmospheric pressure compensation becomes difficult requiring manual intervention
Solution Approach 1:
The patent enables the sensor to perform self-service atmospheric pressure compensation by automatically exiting the fluid, measuring atmospheric pressure to update the offset, and returning to fluid measurement. This autonomous behavior eliminates manual intervention while maintaining continuous flow measurement capability.
Solution Approach 2:
The patent implements periodic atmospheric pressure sampling where the sensor periodically exits the fluid to refresh its atmospheric pressure offset measurement. This periodic action ensures accurate compensation without requiring continuous manual intervention, balancing continuous flow measurement with automatic calibration.
4Measurement precision
If the pressure sensor is removed from the fluid to measure atmospheric pressure, then atmospheric pressure offset is updated, but measurement continuity is interrupted
Solution Approach 1:
The patent performs preliminary atmospheric pressure measurement during installation or maintenance periods when the sensor is naturally exposed to air. This preliminary action captures atmospheric pressure data before fluid measurement begins, eliminating the need for frequent interruptions during operational measurement.
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
Enables accurate fluid depth and flow rate measurements without the drawbacks of differential pressure sensors, reducing user error and maintenance needs while maintaining accuracy.
Implementation Method 1
measuring an atmospheric pressure with the absolute pressure sensor to determine an offset pressure measurement
Implementation Method 2
determining that an absolute pressure sensor is not submersed in a fluid
Data Source
AI summary
One aspect provides a method including determining that an absolute pressure sensor is not submersed in a fluid; measuring an atmospheric pressure with the absolute pressure sensor to determine an offset pressure measurement; submersing the absolute pressure sensor in a fluid; and measuring pressure with the absolute pressure sensor; wherein a compensated pressure measurement of the fluid is determined. Other embodiments are disclosed.