Flow Rate Measuring Device with Dual-Function Resistive Sensor
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Solution Overview
Problem
The integration of electromagnetic type open-close valves near flow rate measuring devices or controllers leads to temperature variations between pressure sensors and fluid resistance members, resulting in measurement errors, and increasing the number of temperature sensors compromises downsizing requirements.
Innovation Solution
A flow rate measuring device with a fluid resistance member, upstream and downstream pressure sensors that measure pressure and temperature using resistive elements, and a temperature sensor to accurately calculate flow rates, while maintaining compactness by sharing resistive elements for both pressure and temperature measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If electromagnetic type open-close valve is arranged near the flow rate measuring device, then device compactness is improved, but temperature variations between pressure sensors and fluid resistance member cause measurement errors
Solution Approach 1:
The resistive element is designed to perform dual functions: measuring pressure through deformation-induced resistance change and measuring temperature through temperature-dependent resistance change. This allows the system to maintain compactness with a single integrated sensor while obtaining both pressure and temperature data needed for accurate flow rate calculation
Solution Approach 2:
The system uses the temperature measurement from the resistive element to compensate for temperature-induced measurement errors in the pressure sensor and fluid resistance member. By continuously monitoring temperature and adjusting calculations accordingly, the system maintains measurement accuracy despite thermal variations caused by nearby electromagnetic valves
2Measurement precision
If the number of temperature sensors is increased to measure temperatures at different locations, then measurement accuracy is improved, but device downsizing requirements cannot be met
Solution Approach 1:
The resistive element serves as both a pressure sensor and a temperature sensor simultaneously. By utilizing the temperature-dependent characteristics of the resistive element's electrical resistance, the system obtains temperature information without adding separate temperature sensing components, thus maintaining device compactness while improving measurement accuracy
Solution Approach 2:
The patent combines the pressure sensing function and temperature sensing function into a single resistive element. This merging of functions eliminates the need for multiple separate sensors, reducing device complexity and size while providing comprehensive measurement data for flow rate calculation
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 configuration allows for precise flow rate calculation despite temperature variations, enhancing measurement accuracy without compromising device compactness, and can be applied to flow rate controllers in semiconductor processes.
Implementation Method 1
an upstream side pressure sensor that has a pressure sensitive surface onto which the target fluid on an upstream side in the fluid resistance member is introduced, the upstream side pressure sensor configured to separately or simultaneously operate in a pressure measurement mode in which pressure of the target fluid is measured from a change of an electrical resistance value of a resistive element that is provided so as to be deformed in conjunction with deformation of the pressure sensitive surface
Implementation Method 2
operate in a temperature measurement mode in which a temperature of the upstream side pressure sensor is measured from a temperature-dependent change of the electrical resistance value of the resistive element
Implementation Method 3
due to heat generated from the electromagnetic type open-close valve or the like at the time of applying current
Data Source
AI summary
A flow rate measuring device includes a fluid resistance member through which measurement target fluid flows; an upstream side pressure sensor configured to measure pressure on an upstream side of the fluid resistance member from a change of electrical resistance of a resistive element attached to a pressure sensitive surface onto which the target fluid is introduced, and also to measure a temperature of the pressure sensitive surface from a temperature-dependent change of the electrical resistance of the resistive element; a temperature sensor to measure a temperature of the target fluid flowing through the fluid resistance member; and a flow rate calculation part that calculates a flow rate of the target fluid based on the pressure measured by the upstream side pressure sensor, pressure-flow rate characteristics of the fluid resistance member, the upstream side pressure sensor temperature, and the target fluid temperature in the fluid resistance member.