Thermal Flow Meter Bypass Passage and Protruding Temperature Sensor
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Solution Overview
Problem
Existing thermal flow meters face challenges in maintaining reliability and measurement accuracy for gas temperature detection when combining flow rate and temperature measurement functions in a single device, as the arrangement of detection elements can lead to interference and reduced accuracy.
Innovation Solution
A thermal flow meter design featuring a bypass passage and a circuit package that includes both flow rate measurement and temperature detection components, with a resin housing and external terminals for signal output, where the temperature detecting portion protrudes to minimize heat transfer and interference from the main passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the thermal flow meter and temperature sensor are combined into one device with detection elements arranged in the measurement target gas, then the device complexity is reduced, but the measurement precision and reliability of temperature detection deteriorate due to interference between detection elements
Solution Approach 1:
The detection elements are segmented into separate functional components: the thermal flow meter measures flow rate through heat transfer in a bypass passage, while the temperature sensor is positioned separately in the main passage. This segmentation eliminates interference between the two measurement functions while maintaining integration in a single device.
Solution Approach 2:
The temperature detecting portion is extracted from the thermal flow meter's measurement path and positioned independently in the main passage. This extraction removes the source of interference while preserving both measurement capabilities within the unified device structure.
2Volume of moving object
If the temperature detecting portion is positioned close to the flow rate measurement component, then the device compactness is improved, but the reliability of temperature detection deteriorates due to heat transfer interference
Solution Approach 1:
The device is segmented into two independent measurement zones: the bypass passage for flow rate measurement and the main passage for temperature measurement. This spatial segmentation maintains compactness while preventing thermal interference between the two measurement functions.
Solution Approach 2:
The bypass passage acts as an intermediary structure that allows the thermal flow meter to measure flow rate without directly interfering with the temperature sensor's measurement path. The bypass passage mediates the interaction between the two measurement components, enabling close proximity without thermal contamination.
3Device complexity
If the detection elements are arranged in series in the measurement target gas, then the device structure is simplified, but the measurement precision deteriorates due to interference between elements
Solution Approach 1:
The measurement function is segmented into two parallel paths: the bypass passage for flow rate measurement and the main passage for temperature measurement. This segmentation allows both measurements to occur simultaneously without interference, maintaining structural simplicity while improving measurement precision.
Solution Approach 2:
The unified device structure serves multiple functions simultaneously: the bypass passage enables flow rate measurement while the main passage enables temperature measurement. This multi-functionality is achieved through a single integrated device with separate measurement paths, simplifying the overall structure while maintaining high measurement precision.
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 design enhances the reliability and accuracy of temperature detection while maintaining high flow rate measurement accuracy, reducing the influence of heat and fluid resistance, and improving overall measurement precision.
Implementation Method 1
a measurement circuit for measuring a flow rate by performing heat transfer with the measurement target gas flowing through the bypass passage
Implementation Method 2
a temperature detecting portion for detecting a temperature of the measurement target gas
Data Source
AI summary
Provided is a thermal flow meter to improve the measurement accuracy of a temperature detector. The thermal flow meter includes a bypass passage through which a measurement target gas flowing through a main passage flows, and a circuit package which includes a measurement circuit for measuring a flow rate of the measurement target gas flowing through the bypass passage and a temperature detecting portion for detecting a temperature of the measurement target gas. The circuit package includes a circuit package body which is molded by a resin to internally envelope the measurement circuit and a protrusion molded by the resin. The temperature detecting portion is provided in the leading end portion of the protrusion, and at least the leading end portion of the protrusion protrudes to the outside from a housing.