Gas Sensor Oxygen Correction for Exhaust Measurement
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Solution Overview
Problem
Existing gas concentration measuring devices inaccurately measure specific gas concentrations in exhaust gases due to fluctuations in oxygen concentration, as the discharge of oxygen by the pump cell affects the pressure and flow of measured gases, leading to discrepancies between actual and measured gas concentrations.
Innovation Solution
Incorporating an oxygen concentration measuring unit and a computation unit that uses the measured oxygen concentration and sensor current to accurately compute the specific gas concentration, with a gas sensor configuration including a measured gas chamber, reference gas chamber, diffusion resistance unit, pump cell, and sensor cell, and employing equations to correct for variations in diffusion resistance characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pump cell is used to discharge oxygen from the measured gas chamber, then the specific gas concentration can be measured, but the pressure and flow of measured gas are affected leading to measurement inaccuracy
Solution Approach 1:
The patent introduces a feedback mechanism where the oxygen concentration measuring unit continuously monitors the oxygen concentration in the measured gas, and the computation unit uses this feedback information to correct the specific gas concentration calculation. This closed-loop feedback system compensates for the pressure and flow disturbances caused by the pump cell's oxygen discharge operation.
Solution Approach 2:
The patent uses an intermediary approach by introducing a separate oxygen concentration measuring unit that acts as a mediator between the pump cell's oxygen discharge operation and the specific gas concentration measurement. This intermediary unit provides correction data that allows the system to distinguish between changes caused by oxygen discharge and changes caused by actual specific gas concentration variations.
2Measurement precision
If oxygen is discharged by the pump cell, then the specific gas can be measured, but the pressure change affects the flow of measured gas into the gas chamber
Solution Approach 1:
The patent replaces complex mechanical pressure control mechanisms with an computational correction approach. Instead of using additional mechanical devices to maintain constant pressure in the gas chamber, the system uses the computation unit to calculate and correct for pressure-induced measurement errors based on data from the oxygen concentration measuring unit.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the calculation parameters for specific gas concentration based on the measured oxygen concentration. The computation unit modifies the measurement interpretation according to the actual oxygen levels, allowing the system to accommodate pressure variations without complex mechanical control.
3Measurement precision
If the gas sensor measures specific gas concentration, then the concentration can be detected, but oxygen concentration fluctuations cause discrepancies in the measurement
Solution Approach 1:
The patent converts the harmful effect of oxygen concentration fluctuations into a beneficial correction mechanism. The oxygen concentration measuring unit, which initially appears to add complexity, actually provides the correction data needed to eliminate measurement errors. The system uses the measured oxygen levels to compensate for their interfering effect on the specific gas concentration measurement.
Solution Approach 2:
The oxygen concentration measuring unit serves as an intermediary that mediates between the harmful oxygen concentration fluctuations and the specific gas concentration measurement. By separately measuring oxygen concentration and using this information for correction, the system isolates and compensates for the interfering factor without disrupting the primary measurement function.
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 configuration enables precise measurement of specific gas concentrations in exhaust gases, reducing the impact of oxygen concentration fluctuations and improving accuracy by using the oxygen concentration measuring unit to reflect oxygen levels in the computation of specific gas concentrations.
Implementation Method 1
a gas sensor configured to measure a concentration CNOX of specific gas contained in measured gas
Implementation Method 2
When a voltage is applied to the pump cell, oxygen is reduced on the pump electrode to generate oxygen ion. The generated oxygen ion is conducted through the solid electrolyte body to move toward the reference electrode
Implementation Method 3
A diffusion resistance portion for controlling a rate of the measured gas is provided at an inlet of the measured gas chamber
Data Source
AI summary
A gas sensor, an oxygen concentration measuring unit, and a computation unit are included. The gas sensor measures a concentration CNOX of specific gas contained in measured gas. The oxygen concentration measuring unit measures a concentration CO2 of oxygen in the measured gas outside the gas sensor. The gas sensor has a measured gas chamber, a reference gas chamber, a diffusion resistance unit, a pump cell, and a sensor cell. The computation unit computes a concentration CNOX of the specific gas by using the concentration CO2 of oxygen measured by using the oxygen concentration measurement unit and the sensor current.