Gas Sensor Adjustment Pump Control for Water-Variation Stability
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Solution Overview
Problem
The accuracy of gas concentration measurements in gas sensors is reduced due to variations in water concentration in the measurement-object gas, leading to inconsistencies in pump current values.
Innovation Solution
A gas sensor with a control device that performs adjustment-pump and measurement-pump control processes, adjusting oxygen concentrations using specific voltage target values to stabilize the measurement-pump current, ensuring accuracy despite water concentration variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If water concentration in measurement-object gas varies, then pump current value varies, but measurement accuracy deteriorates
Solution Approach 1:
The patent introduces an oxygen concentration adjustment chamber as an intermediary component between the measurement chamber and the external environment. This chamber contains an adjustment pump cell that actively controls oxygen concentration, serving as a buffer that isolates the measurement system from variations in water concentration in the measurement-object gas, thereby preventing water concentration changes from directly affecting pump current and measurement accuracy
Solution Approach 2:
The patent dynamically adjusts the oxygen concentration in the oxygen concentration adjustment chamber by controlling the adjustment pump cell to maintain a target oxygen concentration. By changing and controlling the oxygen concentration parameter in the intermediary chamber, the system compensates for the effects of varying water concentration in the measurement gas, stabilizing the measurement conditions and ensuring consistent measurement accuracy regardless of water concentration variations
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 effectively prevents reductions in measurement accuracy due to water concentration fluctuations by stabilizing the measurement-pump current, maintaining precise gas concentration readings.
Implementation Method 1
an element body that includes an oxygen-ion-conductive solid electrolyte layer
Implementation Method 2
a measurement pump cell including an inner measurement electrode disposed in a measurement chamber of the measurement-object gas flow portion, the measurement pump cell being configured to pump oxygen from the measurement chamber to an outside of the element body
Implementation Method 3
an adjustment pump cell including an inner adjustment electrode disposed in an oxygen concentration adjustment chamber located upstream of the measurement chamber, the adjustment pump cell being configured to adjust an oxygen concentration in the oxygen concentration adjustment chamber
Data Source
AI summary
A gas sensor includes a sensor element and a control device, the sensor element including: a measurement pump cell, an adjustment pump cell including an inner adjustment electrode disposed in an oxygen concentration adjustment chamber, and a reference electrode. The control device is configured to control the adjustment pump cell so that an adjustment voltage that is a voltage across the reference electrode and the inner adjustment electrode reaches an adjustment voltage target value, and let V1* [mV] be the adjustment voltage target value, then following Expression (1) and Expression (2) are satisfied: V1*≤−25.7*R+436.0 (1) V1*≥−35.1*R+406.6 (2), where R=Lb*Lb/La, La is a limiting current value [mA] of an adjustment pump current which flows through the adjustment pump cell and Lb is a limiting current value [μA] of a measurement pump current which flows through the measurement pump cell.