Undulated Separating Membrane for Linear Pressure Deflection
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Solution Overview
Problem
Existing separating membranes in industrial process measurement technology suffer from non-linearity in pressure-volume relationships, leading to measurement errors due to thermal expansion and rigidity limitations, particularly in axisymmetrical designs which are more expensive to produce.
Innovation Solution
A separating membrane with a planar edge region, an offset working region, and a frustoconical transition region, featuring an undulation pattern that decreases in amplitude from the inside to the outside, ensuring a linear characteristic curve with a low coefficient of determination deviation and maintaining axisymmetry up to a dimensionless pressure equivalent of 250, thereby enhancing linearity and stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the embossing depth H is increased to improve linearity, then the separating membrane becomes more rigid for small deflections, but the maximum embossing depth is limited by material constraints (H/h ratio)
Solution Approach 1:
The separating membrane is divided into distinct functional zones: a planar edge region for joining, a frustoconical transition region for stress distribution, and a working region with undulation pattern for volume compensation. This segmentation allows each zone to optimize its function without compromising the others.
Solution Approach 2:
Different regions of the separating membrane are given different geometric properties: the edge region is planar for secure joining, the transition region has a frustoconical shape for stress distribution, and the working region features an undulation pattern with specific amplitude ratios for linear volume compensation. This local differentiation resolves the contradiction between rigidity and adaptability.
2Ease of manufacture
If an axisymmetrical separating membrane design is used to simplify manufacturing, then production costs increase compared to non-axisymmetrical designs
Solution Approach 1:
While the overall membrane maintains axisymmetry for manufacturing simplicity, the undulation pattern within the working region introduces controlled asymmetry in the form of radial waves with specific amplitude ratios. This controlled asymmetry achieves the desired linear characteristic curve while maintaining ease of manufacture through rotational symmetry.
Solution Approach 2:
The invention optimizes specific geometric parameters of the undulation pattern, particularly the amplitude ratio between adjacent waves (between 0.5 and 1.5), to achieve linear pressure-volume characteristics. This parameter optimization maintains axisymmetrical manufacturing while improving linearity performance.
3Measurement precision
If the separating membrane is made softer to reduce measurement error from thermal expansion, then the linearity of the pressure-volume relationship deteriorates
Solution Approach 1:
The frustoconical transition region and the undulation pattern in the working region introduce controlled curvatures that distribute stress evenly during deflection. This geometric curvature design allows the membrane to remain relatively soft for accurate thermal expansion compensation while maintaining linear pressure-volume characteristics through the optimized undulation geometry.
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 provides a significantly improved linear relationship between pressure and volume displacement, reducing measurement errors and maintaining consistency across varying pressure differences, outperforming prior art designs in terms of linearity and stiffness without increasing production costs.
Implementation Method 1
p is the pressure difference between the two sides of the separating membrane, which causes a deflection
Implementation Method 2
The separating membranes are in particular deflected by the thermal expansion of the transfer fluid
Data Source
AI summary
A separating membrane includes: a planar edge region for the joining of the separating membrane to a diaphragm seal body; a working region offset in an axial direction relative to the edge region; and a transition region between the edge region and the working region, wherein the transition region extends over a radial region of not more than one quarter of an outer radius of the transition region, wherein the working region has a substantially planar center and an embossed pattern or undulation pattern between the center and an outer edge of the working region, wherein from the rest position to a point of deflection with a dimensionless pressure equivalent, the separating membrane has a characteristic curve in which, for a coefficient of determination R2 of a linear regression of the characteristic curve, the following applies: (1−R2)<1%.