Thermal Flow Meter Phase Difference Measurement
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Solution Overview
Problem
Existing thermal type flow meters face challenges in accurately measuring flow rates of various fluids without high development costs and complex user operations, as they require large internal memory and numerous correlation functions to account for different fluid types.
Innovation Solution
A thermal type flow meter with a first resistor for self-heating and a second resistor for fluid temperature measurement, using a current application unit to generate a temperature difference signal, and an arithmetic unit to determine parameters for converting this difference into a target value, allowing for the calculation of flow rates across different fluid types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple correlation functions are stored for different fluid types, then measurement precision is improved, but device complexity and internal memory requirements increase
Solution Approach 1:
The patent changes the measurement parameter from absolute temperature difference to phase difference between temperature oscillation and drive signal. This parameter transformation allows universal measurement across different fluid types without requiring fluid-specific correlation functions, as the phase difference relationship remains consistent regardless of fluid characteristics.
Solution Approach 2:
The invention creates a universal measurement method that works for all fluid types using a single correlation relationship between phase difference and flow rate. The measurement system becomes multi-functional, capable of measuring different fluids (oils, water, etc.) with the same algorithm, eliminating the need for multiple fluid-specific correlation functions.
2Measurement precision
If multiple correlation functions are stored for different fluid types, then measurement precision is improved, but development costs increase
Solution Approach 1:
By transforming the measurement approach to use phase difference rather than absolute temperature difference, the patent eliminates the need for expensive fluid-specific calibration and correlation function acquisition. The phase difference method provides a universal relationship that works across all fluid types without requiring separate development for each fluid.
3Measurement precision
If multiple correlation functions are stored for different fluid types, then measurement precision is improved, but ease of operation decreases
Solution Approach 1:
The universal phase difference measurement method allows the flow meter to operate with a single set of parameters for all fluid types. Users no longer need to select or configure different correlation functions based on fluid type, significantly simplifying the operation while maintaining measurement precision through the robust phase difference relationship.
4Measurement precision
If multiple correlation functions are stored for different fluid types, then measurement precision is improved, but adaptability decreases
Solution Approach 1:
The patent simplifies the operational understanding by changing from a complex multi-function system requiring fluid identification and correlation function selection to a single universal method. The phase difference measurement approach is inherently easier to understand and apply, as it relies on a fundamental trigonometric relationship that works universally across all fluid types.
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 simple and cost-effective flow rate detection for various fluids by canceling out differences in fluid characteristics, reducing memory requirements and simplifying operations, while maintaining accurate flow rate measurements.
Implementation Method 1
a first resistor R1 which is disposed along a flow path through which a fluid flows, in which heat is generated when a current is applied
Implementation Method 2
a current application unit configured to apply a current to the first resistor R1 so that an output signal of the first resistor R1 indicates a predetermined temperature
Data Source
AI summary
A thermal type flow meter includes a first resistor (R1) is disposed along a flow path through which a fluid flows, generating heat when a current is applied, and outputting a first output signal indicating a heat generation temperature, a second resistor (R2) disposed at a position different from that of the first resistor along the flow path and outputting a second output signal indicating a temperature of the fluid, and a current application unit configured to apply a current to the first resistor so that the first output signal indicates a predetermined temperature. A parameter for converting the difference between the first output signal and the second output signal when a predetermined input is received if the current is applied into a target value is determined. The flow rate is acquired using the parameter, the difference detected after the parameter is determined, and a predetermined function.