CO2 Sensor Air Pressure Compensation via Reference Gas
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Solution Overview
Problem
Existing CO2 sensors in non-stationary environments, such as vehicles, experience measurement deviations due to air pressure changes, which are not adequately compensated by existing technologies, leading to inaccurate CO2 concentration readings.
Innovation Solution
A sensor arrangement that includes an evaluation unit to calculate air pressure and apply compensation to CO2 concentration measurements using a constant atmospheric CO2 content, combined with temperature compensation and integration with the ventilation system to adjust for air pressure fluctuations, ensuring accurate CO2 monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure sensors are used for pressure compensation, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses an intermediary substance (reference gas with known CO2 concentration) to indirectly determine air pressure effects. Instead of directly measuring pressure with a pressure sensor, the system introduces a reference gas and compares its measured concentration against the known actual concentration. The deviation between measured and actual values serves as an indirect indicator of air pressure effects, allowing compensation without requiring direct pressure sensing hardware.
Solution Approach 2:
The patent creates a reference measurement copy of the CO2 detection process using a reference gas channel. This reference channel replicates the measurement conditions but with a known CO2 concentration. By comparing the reference channel output with the measurement channel output, the system can identify and compensate for air pressure-induced deviations without needing separate pressure sensing components.
2Measurement precision
If pressure compensation is implemented in stationary sensor arrangements, then measurement precision is improved, but cost increases
Solution Approach 1:
The reference gas acts as an intermediary that enables compensation for air pressure effects without requiring expensive pressure sensors. The known concentration of CO2 in the reference gas provides a reference point against which measurement deviations can be compared, allowing the system to calculate and compensate for air pressure effects through software algorithms rather than additional hardware components.
Solution Approach 2:
The system performs self-compensation by using its own measurement capabilities to detect air pressure effects. The reference gas channel and measurement channel are both processed by the same evaluation unit, which automatically compares their outputs and applies compensation algorithms. This self-service approach eliminates the need for separate pressure sensing subsystems and reduces overall system cost.
3Device complexity
If air pressure compensation is not implemented, then device complexity is reduced, but measurement precision deteriorates in non-stationary environments
Solution Approach 1:
The system performs preliminary characterization of air pressure effects by continuously monitoring the reference gas channel. Before making CO2 concentration measurements in the measurement channel, the system uses the reference channel to detect current air pressure conditions and pre-calculates compensation factors. This preliminary action ensures that when measurement deviations occur due to air pressure changes in non-stationary environments, the compensation is already prepared and can be applied immediately.
Solution Approach 2:
The system implements a feedback mechanism where the measured concentration in the reference gas channel continuously feeds back to the evaluation unit. This feedback loop allows the system to detect deviations caused by air pressure changes and automatically adjust compensation parameters in real-time. The feedback from the reference channel ensures that the system adapts to changing air pressure conditions in non-stationary environments without requiring complex additional hardware.
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 solution provides reliable and accurate CO2 concentration measurements in non-stationary environments by effectively compensating for air pressure and temperature changes, preventing false alarms and ensuring precise monitoring of CO2 levels.
Implementation Method 1
an NDIR sensor unit that can determine the number of CO2 molecules on an optical measuring section
Implementation Method 2
the evaluation unit can calculate the air pressure from measurement values of the NDIR sensor unit and on the basis of the value calculated for the air pressure or respectively of an air pressure correction value calculated therefrom for the measurement value of the CO2 concentration determined by the NDIR sensor unit, an air pressure compensation is able to be carried out
Implementation Method 3
provided with a temperature sensor that can determine the temperature in the interior space, and with a temperature compensation unit by means of which, on the basis of the measurement value determined by the temperature sensor, a temperature compensation is able to be carried out
Data Source
AI summary
A sensor arrangement for determining the CO2 concentration in an interior space has an NDIR sensor unit that can determine the number of CO2 molecules on an optical measuring section and therefrom the CO2 concentration in an interior space. The sensor arrangement further has an evaluation unit that can calculate the air pressure from measurement values of the NDIR sensor unit and that can carry out an air-pressure compensation on the basis of the value calculated for the air pressure or of an air pressure correction value calculated therefrom for the measurement value of the CO2 concentration determined by the NDIR sensor unit.