Pressure Sensor Base Geometry for Thermal Stress Isolation
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Solution Overview
Problem
Pressure measuring devices face challenges due to thermomechanical stresses caused by the difference in thermal expansion coefficients between metallic housings and semiconductor pressure sensors, leading to reduced measuring accuracy and reproducibility, especially with temperature-dependent hysteresis effects.
Innovation Solution
A pressure measuring device design featuring a carrier made of metal, particularly stainless steel, with a base that has a larger base area than the extension supporting the pressure sensor, where the extension's base area is smaller than the sensor's, and adhesive joints are used to connect the base to the carrier, allowing for better stress compensation and material flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the pressure sensor is mounted directly on a metallic housing, then the structural simplicity is improved, but thermomechanical stresses occur due to different coefficients of thermal expansion, reducing measurement accuracy
Solution Approach 1:
The patent introduces a base as an intermediary component between the metallic housing and the semiconductor pressure sensor. This base serves as a stress-decoupling element that mechanically separates the two components with different thermal expansion coefficients, preventing direct transmission of thermomechanical stresses to the sensor while maintaining structural integrity.
Solution Approach 2:
The housing structure is segmented into distinct components: the metallic housing, the intermediate base, and the pressure sensor mounting area. This segmentation allows each component to be optimized independently - the housing provides structural strength, the base provides stress isolation, and the sensor area maintains measurement precision.
2Stability of the object's composition
If the base area is made larger to improve stability, then the stability is improved, but the alignment precision during assembly becomes more difficult
Solution Approach 1:
The base exhibits local quality variations with a larger overall footprint for stability, but with a localized, precisely defined sensor mounting area. This allows the base to provide broad stability while maintaining a controlled, precision-critical zone for sensor alignment that is optimized for manufacturing accuracy.
Solution Approach 2:
The base design uses asymmetric geometry where the majority of the base area provides stability and mounting surface, while a specific localized region (the sensor mounting area) is precisely dimensioned and positioned. This asymmetric distribution of functional areas allows simultaneous achievement of stability and alignment precision.
3Measurement precision
If a ceramic interlayer is used to match the thermal expansion coefficient, then the temperature-dependent stresses are reduced, but the material cost and manufacturing complexity increase
Solution Approach 1:
The base acts as a mechanical intermediary that decouples the thermal expansion mismatch problem. Instead of requiring material property matching (as with ceramic interlayers), the base provides stress isolation through its structural design and material selection, achieving temperature compensation through mechanical means rather than material science complexity.
Solution Approach 2:
The patent changes the approach from matching material parameters (thermal expansion coefficients) to controlling mechanical parameters (base geometry, material properties, and mounting configuration). This parameter substitution allows achieving stress compensation using more manufacturable materials and processes.
4Measurement precision
If the extension base area is made smaller to reduce stresses, then the stress compensation is improved, but the adhesive application precision and alignment difficulty increase
Solution Approach 1:
The extension features local quality differentiation with a reduced base area at the sensor mounting interface for stress compensation, while maintaining adequate adhesive application area through localized adhesive zones. This allows precise stress management at the critical sensor interface while providing sufficient bonding area for reliable assembly.
Solution Approach 2:
The adhesive bonding is applied partially - only where necessary for stress compensation and structural integrity - rather than across the entire base area. This partial action reduces the complexity of adhesive application precision requirements while maintaining the stress compensation benefits of the reduced extension area.
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 effectively reduces thermomechanical stresses on the pressure sensor, improving measuring accuracy and reproducibility by allowing the base to automatically adjust and align during assembly, and enabling the use of cost-effective materials while minimizing the complexity of precise alignment and adhesive application.
Implementation Method 1
Adhesive bonds are significantly more elastic than rigid connections, such as glazing, and are therefore much better able to compensate for stresses arising from differing coefficients of thermal expansion between the support and the base
Implementation Method 2
Semiconductor pressure sensors are frequently used in pressure measurement technology
Implementation Method 3
The casing and pressure sensor are thus made of materials with very different coefficients of thermal expansion. Due to the mechanical connection required for sensor mounting between the casing and the pressure sensor, thermomechanical stresses can occur
Data Source
Figure 1~2
Figure 3
AI summary
The invention describes a pressure measuring device which can be produced in a simple manner and has a carrier (1, 3, 5), in particular a metal carrier (1, 3, 5), in particular a stainless steel carrier, a pedestal (7, 9, 11) connected to the carrier (1, 3, 5) and a pressure sensor (13) mounted on a free-standing end of the pedestal (7, 9, 11), the pressure sensor (13) of which is protected against thermomechanical stresses and is distinguished by the fact that the pedestal (7, 9, 11) comprises a base (25, 27, 29) arranged on the carrier (1, 3, 5), the pedestal (7, 9, 11) comprises an extension (31) which extends from the base (25, 27, 29) in the direction of the pressure sensor (13) and comprises the free-standing end of the pedestal (7, 9, 11), the base (25, 27, 29) has an area which is greater than an area of the extension (31), and the extension (31) has an area which is smaller than an area of the pressure sensor (13) mounted thereon.