Differential Pressure Sensor With Symmetric Measuring Body
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Solution Overview
Problem
Conventional pressure sensors face issues with sensitivity to temperature and reference pressure, leading to reduced precision and limited resistance to overpressure due to thermal expansion and compressibility of oil, as well as membrane deformation under excess pressure.
Innovation Solution
A pressure sensor design featuring a cavity filled with weakly compressible liquid, where the measuring body is mechanically connected only to one membrane at its center of symmetry, with an overpressure safety device comprising valves to prevent liquid circulation between chambers when pressure differences exceed threshold values, thereby compensating for temperature sensitivity and improving bidirectional measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If oil is used to fill the cavity to limit volume variation, then the pressure sensor can maintain structural stability, but temperature sensitivity increases due to thermal expansion of the oil
Solution Approach 1:
The patent changes the physical parameter of the filling fluid from oil to air or gas, which has different thermal expansion characteristics. This parameter change eliminates the thermal expansion problem that caused temperature sensitivity while maintaining volume stability through the elastic deformation of the diaphragm.
Solution Approach 2:
The patent exploits the thermal expansion properties of air/gas differently than oil. By using a gas-filled cavity with elastic diaphragms, the system allows for thermal expansion without the linear thermal expansion coefficient problems of oil, thereby reducing temperature sensitivity while maintaining structural stability.
2Force
If oil is used in the cavity to transmit pressure, then pressure transmission is achieved, but linear sensitivity to reference pressure occurs due to oil compressibility
Solution Approach 1:
The patent replaces the oil-based mechanical pressure transmission system with an air/gas-filled elastic membrane system. This substitution eliminates the linear sensitivity to reference pressure caused by oil compressibility while maintaining effective pressure transmission through the elastic deformation of the diaphragms.
3Strength
If transmission rods with stops are used to limit displacement, then overpressure resistance is improved, but membrane deformation and damage still occur due to oil displacement
Solution Approach 1:
The patent changes the filling medium from incompressible oil to compressible air/gas, which allows the system to absorb overpressure through compression rather than forcing membrane deformation. This parameter change improves both overpressure resistance and membrane durability simultaneously.
Solution Approach 2:
The elastic diaphragms and gas-filled cavity provide beforehand cushioning against overpressure. The gas compressibility acts as a cushion that absorbs excess pressure energy before it can cause membrane damage, thereby improving reliability without compromising overpressure resistance.
4Adaptability or versatility
If bidirectional measurement capability is implemented, then versatility is improved, but temperature compensation complexity increases
Solution Approach 1:
The patent changes the filling medium parameter from oil to air/gas, which fundamentally alters the temperature compensation requirements. This parameter change simplifies temperature compensation for bidirectional measurement because gas-filled elastic membranes have more predictable and uniform thermal behavior compared to oil-based systems.
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 enhances temperature compensation, reduces sensitivity to reference pressure, and increases resistance to overpressure, maintaining precision across a wider temperature range and preventing membrane damage from excessive pressure.
Implementation Method 1
a cavity (12) which is filled with a liquid
Implementation Method 2
a measuring body (30) which comprises a strain gauge (31)
Data Source
Figure 1~2B
Figure 3
AI summary
The invention relates to a pressure sensor (10) comprising a cavity (12) containing a liquid, said cavity (12) being closed at a first end by a first diaphragm (20a) and at a second end by a second diaphragm (20b), and a measuring body (30) that comprises a strain gauge (31) situated inside said cavity (12), characterized in that the measuring body (30) is mechanically connected only to one diaphragm from the first diaphragm (20a) and the second diaphragm (20b) by a connecting member (50), the measuring body (30) comprising a shape having central symmetry and the connecting member (50) being fastened to the centre of symmetry of said measuring body (30).