Wave-Pattern Separating Membrane for Linear Pressure Measurement
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Solution Overview
Problem
Existing separating membranes in industrial pressure measurement systems suffer from non-linearity due to thermal expansion of transmission fluids, leading to measurement errors, and are costly to produce with extremely soft, non-axisymmetric designs.
Innovation Solution
A separating membrane with a planar edge region, an offset working area, and a transition area with a specific wave pattern that maintains linearity up to a dimensionless pressure equivalent of 250, featuring a coefficient of determination R2< 0.25% and a slope S<20, ensuring axisymmetric shape and reduced measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an extremely soft, non-axisymmetric separating membrane is used to reduce measurement errors, then measurement precision is improved, but manufacturing cost increases and production becomes more difficult
Solution Approach 1:
The patent applies asymmetry in reverse by using axisymmetric symmetry. The separating membrane is designed with rotational symmetry around its central axis, which simplifies manufacturing while maintaining performance. This symmetric design allows for easier production compared to non-axisymmetric designs, directly addressing the manufacturing difficulty issue while achieving the desired measurement precision through controlled membrane geometry and wave pattern parameters.
Solution Approach 2:
The patent utilizes parameter changes by optimizing the wave pattern characteristics (amplitude, wavelength, number of waves) and membrane geometry (radius, thickness distribution) to achieve the desired softness and linearity. By carefully selecting these parameters, the membrane achieves extreme flexibility with R²<0.25% without requiring complex non-axisymmetric shapes, thus maintaining ease of manufacture while improving measurement precision.
2Measurement precision
If a corrugated separating membrane is used to achieve linear pressure-volumetric stroke relationship, then measurement precision is improved, but the membrane stiffness increases causing larger deflection errors
Solution Approach 1:
The patent applies local quality by creating a wave pattern with spatially varying characteristics. The wave amplitude, wavelength, and curvature are optimized at different radial positions and depths of the membrane. This local optimization allows the membrane to maintain low overall stiffness for minimal deflection while providing local corrugation features that ensure linear pressure-volumetric stroke relationship, thus resolving the contradiction between linearity and stiffness.
Solution Approach 2:
The patent utilizes curvature through the wave pattern design, where the membrane features controlled undulations with specific amplitudes and wavelengths. This curvature introduces non-linear elastic behavior that compensates for the non-linearity in the pressure-volumetric relationship, achieving linearity (R²<0.25%) while the distributed nature of the curvature prevents excessive stiffening, maintaining membrane flexibility.
3Measurement precision
If the wave pattern amplitude is increased to improve linearity, then measurement precision is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies partial action by using moderate wave amplitudes rather than extreme values. The wave pattern parameters are optimized to provide sufficient linearity improvement (achieving R²<0.25%) without requiring excessively large amplitudes that would be difficult to manufacture. This balanced approach achieves the desired measurement precision while keeping manufacturing precision requirements at practical, achievable levels.
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 membrane achieves improved linearity and reduced measurement errors by maintaining a consistent rigidity and axisymmetric shape, enhancing the accuracy of pressure measurements while being cost-effective to produce.
Implementation Method 1
the working area between the substantially planar center and the edge of the working area has an embossed pattern or wave pattern... The separating membrane has a characteristic curve p*(w) from the rest position up to a dimensionless pressure equivalent p* of not less than 250... wherein for the coefficient of determination R2
Implementation Method 2
p is the pressure difference between the two sides of the separating membrane, which causes a deflection... the pressure-dependent deflection is comparatively small in most cases
Implementation Method 3
The separation membranes are deflected primarily by the thermal expansion of the transfer fluid... the equilibrium volume of which has a thermal expansion corresponding to the thermal expansion of the transmission fluid in the pressure transmitter chamber
Data Source
Figure 1a~1b
Figure 2~4
AI summary
A separating membrane (100) comprises: a planar edge region (110) for the joining of the separating membrane (100) to a diaphragm seal body (150); a working region (120) which is offset in an axial direction in relation to the edge region (110); a transition region (130) between the edge region (110) and the working region (120), wherein the transition region (130) extends over a radial region of no more than one quarter of the outer radius of the transition region (130); wherein the working region (120) has a substantially planar center (122), wherein the working region (120) has an embossed pattern or undulation pattern (124) between the center (122) and an outer edge of the working region, wherein, in particular, from the rest position to the point of deflection with a dimensionless pressure equivalent p* of no less than 250, the separating membrane (100) has a characteristic curve p*(w), wherein, for the coefficient of determination R2 of a linear regression of the characteristic curve, the following applies: (1 - R2) < 1%.