Thermal Flowmeter Electrostatic Scattering Housing
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Solution Overview
Problem
The existing thermal-type flowmeters face issues with reduced accuracy and reliability due to dimensional instability and strength concerns when using conductive resin materials, increased costs from added metal components, and lower reliability in connection portions, especially when dealing with contamination and electrostatic scattering mechanisms.
Innovation Solution
A thermal-type flowmeter design where a supporting body for the flow rate detection element is fixed to a circuit substrate, with the detection surface facing the substrate, forming an electrostatic scattering mechanism that prevents contamination and maintains accuracy and reliability while reducing costs by eliminating the need for additional components and minimizing linear expansion differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conductive resin material is used to form the electrostatic scattering mechanism, then the attachment of dirty substance is suppressed, but the strength is reduced and dimensional accuracy deteriorates
Solution Approach 1:
The patent merges the electrostatic scattering mechanism with the housing structure by integrating the conductive resin material into the housing itself, rather than using a separate component. This combination maintains the anti-contamination function while improving overall structural strength and dimensional stability through the housing's integral design
Solution Approach 2:
The patent uses composite material construction where the housing incorporates conductive resin material with specific electrical conductivity properties. This composite approach allows the housing to simultaneously provide mechanical support, electrical grounding for electrostatic scattering, and dimensional stability, resolving the contradiction between conductivity and strength
2Object-affected harmful factors
If conductive resin material is used to form the electrostatic scattering mechanism, then the attachment of dirty substance is suppressed, but the accuracy in dimension of the bypass deteriorates
Solution Approach 1:
The patent combines the electrostatic scattering function with the housing structure, allowing the bypass dimensions to be precisely controlled through the housing's integral design rather than being affected by separate conductive components. This merging ensures that the bypass maintains accurate dimensions while still providing electrostatic scattering protection
3Object-affected harmful factors
If a new GND terminal and conductive resin component are added, then the electrostatic scattering mechanism is provided, but the cost is increased
Solution Approach 1:
The patent eliminates the need for separate GND terminals and conductive resin components by integrating the electrostatic scattering function directly into the housing structure. This merger reduces the number of parts, simplifies assembly, and lowers manufacturing costs while maintaining the electrostatic scattering mechanism's effectiveness
Solution Approach 2:
The housing is designed to serve multiple functions simultaneously: providing structural support, forming the bypass passage, and creating the electrostatic scattering mechanism through its conductive material integration. This multi-functionality eliminates the need for additional dedicated components, reducing overall device complexity and cost
4Object-affected harmful factors
If over-molding is performed to provide the electrostatic scattering mechanism, then the electrostatic scattering function is added, but the reliability is lowered due to shape deformation and gaps
Solution Approach 1:
The patent integrates the electrostatic scattering function into the housing structure through material selection and design rather than through over-molding processes. This integration eliminates the shape deformation and gap issues associated with over-molding, as the conductive properties are inherent to the housing material itself rather than being added as a separate layer
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 enhances the flow rate accuracy and reliability of the thermal-type flowmeter, prevents contamination, and reduces costs by integrating the electrostatic scattering mechanism into the basic components, ensuring high durability and contamination resistance.
Implementation Method 1
measure a mass flow rate in the pipe using a change in electric resistance caused by a cooling action of the flowing gas
Implementation Method 2
a change in electric resistance caused by a cooling action of the flowing gas
Implementation Method 3
remove or absorbing electric charges of the dirty substance entered in the bypass with the above configuration
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
Provided is a thermal-type flowmeter which can prevent a reduction of flow rate accuracy and reliability, and an increase of cost of the thermal-type flowmeter compared to the related art, and can add a function of an electrostatic scattering mechanism. The thermal-type flowmeter 1 of the present invention includes a sub-passage 200 into which part of a measurement target gas 5 flowing in a main passage is taken, a flow rate detection element of a flow measurement unit 300 which is disposed in the sub-passage 200, a circuit package 301 which supports the flow rate detection element, and a substrate 101 to which the circuit package 301 is fixed. The flow rate detection element includes a detection surface to detect a flow rate of the measurement target gas. The detection surface is disposed to face the circuit substrate.