Overlapping Pressure Sensor Calibration for Gas-Independent Vacuum Measurement
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Solution Overview
Problem
Existing pressure sensors struggle to provide accurate measurements across a wide range of pressures, particularly in varying gas compositions, as different types of sensors have different measuring ranges and gas dependencies, leading to inaccuracies and the need for complex calibration methods.
Innovation Solution
A method for operating a group of pressure sensors that includes simultaneously reading signals from two sensors with overlapping ranges, defining an adjustment point, determining gas-dependent calibration parameters, and using these parameters to correct pressure measurements, thereby minimizing gas-type dependency and enhancing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pressure sensor type is used, then the device complexity is reduced, but the measurement precision deteriorates because no single sensor can accurately measure across the entire pressure range from atmospheric to ultra-high vacuum
Solution Approach 1:
The patent combines multiple pressure sensors with different measurement principles (thermal conductivity sensor and ionization sensor) into a single integrated device. This merging allows the system to leverage the strengths of each sensor type - the thermal conductivity sensor for higher pressures and the ionization sensor for vacuum ranges - achieving accurate measurements across the entire pressure spectrum while maintaining a unified device structure
2Measurement precision
If different pressure sensors with overlapping ranges are combined, then the measurement precision is improved across the entire pressure range, but the device complexity increases due to the need for multiple sensors and calibration mechanisms
Solution Approach 1:
The patent implements an automated calibration system that uses feedback from the overlapping measurement range of two sensors. During a calibration phase, the system compares readings from both sensors in their overlap region and automatically adjusts calibration parameters to align their outputs. This feedback mechanism eliminates manual calibration complexity while maintaining high measurement precision across the full pressure range
Solution Approach 2:
The patent changes the operational parameters of the sensors by switching between different measurement principles based on pressure range. The system dynamically adjusts which sensor is active and applies range-specific calibration parameters, allowing each sensor to operate in its optimal range and simplifying the overall system management while maintaining high accuracy
3Measurement precision
If thermal conductivity pressure sensors are used, then the measurement precision is improved in vacuum ranges, but the reliability deteriorates because the measurements depend on gas composition and require frequent calibration
Solution Approach 1:
The patent introduces an intermediary calibration system that mediates between the thermal conductivity sensor and ionization sensor. This intermediary calibration mechanism uses the overlapping measurement range and known gas composition data to continuously adjust and validate the thermal conductivity sensor readings, compensating for gas composition dependencies and maintaining reliable measurements without frequent manual calibration
Solution Approach 2:
The patent makes the pressure measurement system universal by implementing a multi-functional sensor arrangement that can accurately measure both gas-dependent and gas-independent pressure ranges. The system automatically selects and switches between measurement principles based on pressure range and gas composition, providing reliable measurements across diverse conditions without requiring separate dedicated sensors for each scenario
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 method enables precise pressure determination independent of gas composition, extending the measurement range and improving accuracy across the entire pressure spectrum, reducing the need for additional gas analyzers and residual gas detectors.
Implementation Method 1
Thermal conductivity vacuum gauges determine the pressure via the pressure-dependent thermal conductivity of a gas, for example, in the case of a Pirani vacuum gauge or Pirani sensor, by determining the heat output transferred from a current-carrying wire to the surrounding gas.
Implementation Method 2
Ionization manometers, another type of pressure sensor, indirectly measure pressure by determining the gas-specific density. The gas density is determined by ionizing the gas molecules with electrons based on the neutralization rate of the ions on a collector electrode, which is determined by measuring the current.
Implementation Method 3
pressure sensors whose measuring principle is based on the deformation of a diaphragm due to a pressure difference between the two sides of the diaphragm, such as capacitance diaphragm gauges (CDGs)
Data Source
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AI summary
Method (100) for operating a group of pressure sensors, wherein the group comprises at least a first pressure sensor with a first pressure measurement range and a second pressure sensor with a second pressure measurement range, wherein the first and second pressure sensors are arranged in such a manner that they can measure the pressure in a common measurement volume, wherein the first and second pressure measurement ranges overlap in an overlap pressure measurement range, and wherein the method comprises the steps of: aa) reading out (101) a first measurement signal from the first pressure sensor and a second measurement signal from the second pressure sensor substantially at the same time while the pressure in the common measurement volume is in the overlap pressure measurement range; bb) stipulating (102) the first measurement signal which has been read out as the adjustment point for the second pressure sensor; cc) determining (103) at least one calibration parameter, in particular a gas-dependent calibration parameter, for the second pressure sensor as a function of the first measurement signal, as a function of the adjustment point for the second pressure sensor, as stipulated in step bb), and as a function of the second measurement signal. The invention also relates to a method for operating a vacuum process plant, to an apparatus for carrying out the method and to a computer program product.