Pressure Sensor Gel Housing Orifice Thermal Expansion
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Solution Overview
Problem
Pressure sensors used in applications with significant temperature variations, such as in the tyre industry, often yield inaccurate pressure data over repeated cycles due to thermal expansion issues within the encapsulant housing.
Innovation Solution
A pressure sensor design that includes an orifice for pressure-equalizing communication between the gel housing and the external environment, allowing for the release of trapped liquids and reducing the risk of local pressure buildup, thereby maintaining accurate pressure measurements across varying temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electronic component is hermetically sealed in an encapsulant filled with gel, then the electronic component is protected from corrosion and mechanical damage, but liquid can become trapped during thermal cycling causing inaccurate pressure readings
Solution Approach 1:
The encapsulant is divided into two distinct chambers: a first chamber containing the gel for shock absorption and corrosion protection, and a second chamber containing the incompressible liquid for pressure transmission. This segmentation prevents liquid entrapment at the gel-encapsulant interface while maintaining both protection and measurement functions.
Solution Approach 2:
The deformable diaphragm acts as an intermediary element between the incompressible liquid and the proof body. It transmits pressure from the liquid to the proof body without allowing direct contact between the gel and the pressure measurement pathway, thereby preventing liquid entrapment while maintaining signal transmission.
2Object-affected harmful factors
If the encapsulant is completely sealed, then the gel can effectively protect the electronic component, but thermal expansion of trapped liquid causes pressure reading errors
Solution Approach 1:
The encapsulant is divided into two distinct chambers: a first chamber containing the gel for shock absorption and corrosion protection, and a second chamber containing the incompressible liquid for pressure transmission. This segmentation prevents liquid entrapment at the gel-encapsulant interface while maintaining both protection and measurement functions.
Solution Approach 2:
Different regions of the encapsulant are assigned different functions: the first chamber provides protective cushioning with gel, while the second chamber provides accurate pressure transmission with incompressible liquid. This local differentiation ensures that the protective function does not interfere with the measurement function.
3Strength
If the gel fills the entire housing space, then maximum protection is provided, but liquid has no escape path during thermal cycles
Solution Approach 1:
The encapsulant is divided into two distinct chambers: a first chamber containing the gel for shock absorption and corrosion protection, and a second chamber containing the incompressible liquid for pressure transmission. This segmentation prevents liquid entrapment at the gel-encapsulant interface while maintaining both protection and measurement functions.
Solution Approach 2:
The incompressible liquid is extracted from the gel chamber and placed in a separate second chamber. This extraction eliminates the problem of liquid entrapment within the gel matrix while preserving the protective function of the gel in its designated space.
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
The solution effectively resolves the issue of inaccurate pressure readings by preventing liquid entrapment and subsequent pressure buildup, ensuring reliable sensor performance during repeated thermal cycles.
Implementation Method 1
an incompressible liquid, in which an electronic component is immersed, said incompressible liquid being able to relay the external pressure to said proof body
Implementation Method 2
a deformable membrane sensitive to the external pressure and therefore able to transmit this external pressure to the proof body
Implementation Method 3
This body typically comprises an element of the strain gauge type, capable of converting the deformation resulting from the pressure into an electrical signal
Implementation Method 4
As an alternative, the proof body comprises an element of the piezoelectric type
Implementation Method 5
after several cycles the sensor can yield inaccurate pressure data... involving significant variations in temperature... temperatures ranging up to 60° and beyond
Implementation Method 6
The space contained between the electronic member and the encapsulant forms a housing that is typically filled with a gel
Data Source
AI summary
A pressure sensor includes an encapsulant housing an electronic member. The electronic member includes a proof body, which has two opposite sides facing away from each other. On a first side of the proof body is a reference-pressure chamber. On a second side of the proof body facing away from the first side is a pressure-to-be-measured chamber in communication with outside of the encapsulant. Delimited between the electronic member and the encapsulant is a housing for gel. An orifice enables the housing for gel to be in communication with outside of the encapsulant.