Diaphragm Vacuum Measuring Cell Calibration
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Solution Overview
Problem
Existing vacuum measuring cells, particularly those using silicon diaphragms, are limited in their ability to operate effectively in low-pressure ranges and chemically aggressive environments, and require separate calibration for each temperature setting, leading to increased complexity and cost.
Innovation Solution
A method for calibrating a compact diaphragm measuring cell arrangement with integrated heating and electronic measuring circuitry, allowing operation over a wider temperature range, where deviations are measured against a reference at multiple pressure and temperature points, with compensation values stored for later use, enabling flexible operation at various temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon diaphragm measuring cells are used for vacuum measurements, then manufacturing cost is reduced and production volume increases, but measurement precision deteriorates at low pressures below 10^-1 mbar
Solution Approach 1:
The patent changes the material parameter from silicon to ceramic (alumina) to enable operation at low pressures where silicon sensors fail. The ceramic material maintains measurement precision in the vacuum range below 10^-1 mbar while allowing cost-effective mass production through standardized manufacturing processes.
Solution Approach 2:
The patent employs composite construction combining ceramic diaphragm with metal components (stainless steel housing, connection elements) to achieve both the chemical inertness and mechanical strength required for vacuum measurements, while maintaining cost-effectiveness through optimized material selection in critical zones only.
2Ease of manufacture
If silicon or metallic diaphragm measuring cells are used in chemically aggressive environments, then initial manufacturing cost is reduced, but reliability deteriorates due to corrosion
Solution Approach 1:
The patent changes the chemical composition parameter from reactive silicon/metal to chemically inert ceramic material that resists corrosion from aggressive substances like fluorine and bromic acid, thereby ensuring long-term reliability in chemically aggressive vacuum processes.
Solution Approach 2:
The ceramic diaphragm creates an inert barrier between the measuring cell interior and the chemically aggressive process environment, preventing direct contact and corrosion reactions that would compromise reliability in aggressive chemical atmospheres.
3Measurement precision
If separate calibration is performed for each temperature setting, then measurement precision is maintained, but device complexity and time consumption increase
Solution Approach 1:
The patent implements a universal calibration approach where a single calibration procedure at room temperature serves multiple temperature operating points. Temperature compensation algorithms enable the same calibrated sensor to maintain measurement precision across different temperature settings without requiring separate calibration for each temperature.
Solution Approach 2:
The patent performs preliminary calibration at a reference temperature (room temperature) and stores compensation parameters that are subsequently applied during operation at different temperatures. This preliminary calibration action eliminates the need for repeated calibration procedures at each temperature point.
4Measurement precision
If multiple measuring cell setups are maintained for different temperature settings, then measurement precision across temperature ranges is ensured, but loss of substance and storage complexity increase
Solution Approach 1:
The patent makes a single measuring cell universal across multiple temperature applications through temperature compensation calibration. This eliminates the need to maintain separate inventories of measuring cells for different temperature ranges, reducing inventory costs and simplifying warehousing while maintaining measurement precision.
Solution Approach 2:
The patent enables a single measuring cell to be reused across different temperature applications by recovering and applying temperature compensation parameters. This eliminates the need to discard or set aside specific measuring cells for particular temperature ranges, optimizing inventory utilization.
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 approach allows a single measuring cell to be used across multiple temperature settings, enhancing precision, flexibility, and reducing costs by eliminating the need for multiple cell setups, while simplifying order transactions and warehousing.
Implementation Method 1
a heating means is provided for heating the measuring cell to a constant temperature
Implementation Method 2
pressurizing a thin diaphragm and measuring its deflection
Implementation Method 3
the capacitance change is analyzed in known manner, which change correlates with the pressure change
Data Source
AI summary
Calibrating a measuring cell arrangement having a diaphragm vacuum measuring cell having a programmable heater for heating the diaphragm vacuum measuring cell to a constant presettable temperature. The heater encompasses the measuring cells and is encompassed by an insulation jacket. The method includes setting a first heating temperature on the measuring cell to a constant preset value, performing a first calibration step by generating at least one preset pressure in a vacuum volume and obtaining vacuum measuring signals of the measuring cell and at least one reference measuring cell, storing pressure values in the memory, determining compensation values from the difference values of the measuring cell and the reference measuring cell, intermediately storing these difference values in a calibration data memory and gauging the measuring cell by transmitting the determined compensation values to the measuring cell data memory.