Universal Sensor Controller for Thermal Anemometer
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Solution Overview
Problem
Conventional fluid property measurement systems, such as thermal anemometers, require different circuit designs and sensor configurations for various modes of operation, leading to complexity and high precision component requirements, which increases costs and complicates calibration and field servicing.
Innovation Solution
A system utilizing an analog-to-digital converter, multiplexer, and microcontroller to measure voltages and adjust currents in a measurement circuit, allowing configuration as a constant temperature, proportional temperature difference, or constant power anemometer, enabling calculation of flow velocity and other fluid properties with reduced component precision and simplified calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional thermal anemometers use different circuit designs and sensor configurations for various modes of operation, then measurement functionality is achieved, but device complexity increases
Solution Approach 1:
The patent implements a single universal measurement circuit that can operate in multiple modes (constant temperature, proportional temperature difference, constant power) by configuring a microcontroller to select different operational parameters. The same hardware components serve all measurement functions, eliminating the need for separate circuit designs for each mode while maintaining measurement versatility.
2Adaptability or versatility
If conventional thermal anemometers use different circuit designs for various modes, then functional capability is achieved, but manufacturing cost increases
Solution Approach 1:
By designing a single universal measurement circuit that can perform multiple measurement modes through software configuration rather than requiring separate hardware circuits for each mode, the patent reduces component count and circuit complexity, thereby lowering manufacturing costs while maintaining the ability to perform diverse measurements.
Solution Approach 2:
The patent merges the functionality of multiple separate measurement circuits into a single integrated measurement circuit that can operate in different modes. This consolidation reduces the total number of components needed, simplifies manufacturing processes, and lowers overall system cost while preserving all required measurement capabilities.
3Measurement precision
If conventional thermal anemometers require high precision components, then measurement accuracy is achieved, but device complexity and cost increase
Solution Approach 1:
The patent employs feedback control where the microcontroller continuously monitors the sensor output and adjusts the heating power or measurement parameters in real-time. This feedback mechanism compensates for variations in component precision, allowing the system to achieve accurate measurements even with standard precision components rather than requiring high precision components throughout the system.
Solution Approach 2:
The patent utilizes parameter changes in the microcontroller's operational settings to optimize measurements. By dynamically adjusting control parameters such as heating power, sampling rate, and calculation methods based on operating conditions, the system maintains measurement accuracy without requiring hardware components to operate at excessively high precision levels.
4Adaptability or versatility
If conventional thermal anemometers use complex circuit designs, then measurement capability is achieved, but calibration and field servicing become complicated
Solution Approach 1:
The patent uses software-based calibration and configuration where the microcontroller stores calibration data and operational parameters in memory. Instead of requiring physical adjustment of complex circuit components during calibration or servicing, the system uses software copies of calibration curves and measurement parameters that can be easily loaded, updated, or reset without touching the hardware, significantly simplifying both calibration and field servicing.
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 and cost-effective fluid property measurement across different modes of operation with reduced precision component requirements, simplifying calibration and field servicing by allowing configuration flexibility and using calibration data to achieve high accuracy fluid velocity measurements.
Implementation Method 1
The device then measures the temperature difference between this heated sensor and a second upstream sensor measuring the fluid temperature. This temperature difference is calibrated against fluid flow velocity.
Implementation Method 2
a single self-heated sensor 202 is operated at a fixed temperature above the fluid temperature
Implementation Method 3
The required power input to self-heated sensor 202 to maintain the fixed temperature varies with the fluid stream velocity and temperature
Implementation Method 4
A typical circuit design used in CTA devices is known as a 'Wheatstone Bridge.' This circuit varies the current through sensor 202 to obtain a null or zero value between the sides of the bridge effectively maintaining the resistance of sensor 202 at a constant value
Implementation Method 5
In the case of a PTDA, resistor 203 is a sensor that is temperature dependent and is in the fluid flow
Data Source
AI summary
A flow switch uses an analog-to-digital converter combined with a multiplexer to measure voltages at one or more points of a measurement circuit and an algorithm within a microcontroller to calculate flow velocity. The measurement circuit has at least one sensor in the fluid stream. The sensor is heated by passing an electric current through the sensor. A second optional upstream sensor is not heated and is at the fluid temperature. The microcontroller then uses the voltage measurements with calibration information and equations based on the desired mode of operation to calculate the flow velocity.