Capacitance Pressure Sensor Thermal Stress Mitigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Capacitance type pressure sensors face challenges due to thermal stress caused by differing thermal expansion coefficients between the sensor main unit, diaphragm, and fixing member, leading to deformation issues during welding.
Innovation Solution
Incorporating first and second ring members with known thermal expansion coefficients to joint the diaphragm to the sensor main unit and fixing member, respectively, to mitigate thermal stress and allow for adjustable tensile force, facilitating easier assembly and reducing deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the diaphragm is welded directly to the sensor main unit, then the structure is simple and manufacturing is easy, but thermal stress causes deformation due to different thermal expansion coefficients
Solution Approach 1:
The patent introduces a first ring member with a known thermal expansion coefficient as an intermediary component between the diaphragm and the sensor main unit. This ring member acts as a thermal expansion buffer that absorbs differential expansion stresses, preventing direct transmission of thermal stress to the diaphragm while maintaining structural integrity and enabling precise welding operations.
Solution Approach 2:
The patent segments the connection structure by dividing the direct diaphragm-to-sensor main unit connection into multiple components: the diaphragm, the first ring member, and the sensor main unit. This segmentation allows each component to be optimized independently for its thermal expansion properties, with the ring member specifically designed to accommodate thermal differential between the other two components.
2Adaptability or versatility
If the flange part is welded to the diaphragm, then the flow path can be properly connected, but thermal stress causes deformation due to different thermal expansion coefficients between diaphragm and flange part
Solution Approach 1:
The patent introduces a second ring member with a known thermal expansion coefficient as an intermediary between the flange part and the diaphragm. This ring member serves as a thermal buffer that absorbs expansion differential stresses during welding, preventing stress transmission to the diaphragm while maintaining the flow path connection functionality.
Solution Approach 2:
The patent segments the flange connection structure by inserting the second ring member between the flange part and the diaphragm. This creates a modular connection system where the ring member can be independently selected for its thermal expansion properties, decoupling the thermal stress from the flow path connection requirement.
3Manufacturing precision
If ring members with known thermal expansion coefficients are introduced, then thermal stress is reduced and manufacturing precision improves, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by selecting ring members with specific known thermal expansion coefficients that match or bridge the thermal expansion properties of adjacent components. By carefully controlling this thermal parameter, the ring members effectively manage thermal stress without requiring complex active control systems or multiple sophisticated components.
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
Prevents diaphragm deformation from thermal stress, allows for adjustable measurement range and precision, and simplifies assembly by using ring members with known thermal expansion coefficients.
Implementation Method 1
there is a problem that, expansion amounts of the sensor main unit and the diaphragm are different because thermal expansion coefficients of the sensor main unit and the diaphragm are different and, therefore, there arises a deformation due to a thermal stress
Data Source
AI summary
The present invention is adapted to prevent a diaphragm from being deformed by a thermal stress caused by thermal expansion coefficients of a sensor main unit and a fixing member and includes a sensor main unit to which a fixed electrode is fixed, a diaphragm structure that forms a sealed space between the diaphragm structure and the sensor main unit and a fixing member that is jointed to the diaphragm structure in a manner of surrounding a pressure receiving part of the diaphragm structure so as to lead a fluid to the pressure receiving part, wherein the diaphragm structure includes a flat plane diaphragm main unit and first and second ring members each having a known thermal expansion coefficient that are respectively provided on both sides of a circumference of the diaphragm main unit.