Gas Sensor Current Correction Using Resistance Change Rate
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Solution Overview
Problem
The accuracy in detecting gas concentration using a gas sensor deteriorates when correction is performed using a relational expression representing a one-to-one correspondence between element temperature and correction amount.
Innovation Solution
A sensor apparatus that calculates gas concentration using a gas sensor with a sensor element and heater, incorporating a solid electrolyte body and electrodes, repeatedly obtains resistance and current information, and corrects the concentration detection current based on internal resistance values, resistance change rates, and target internal resistance values to account for static and transitional states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If correction is performed using a relational expression representing a one-to-one correspondence between element temperature and correction amount, then the correction process is simple, but the accuracy in detecting gas concentration deteriorates
Solution Approach 1:
The patent transitions from a static correction model (one-to-one correspondence between temperature and correction amount) to a dynamic correction model that considers the time-varying nature of internal resistance. By calculating the resistance change rate (dRpvs/dt) and incorporating it into the correction equation, the system adapts to transient states where internal resistance is changing over time, thereby improving measurement accuracy without excessive complexity
Solution Approach 2:
The patent changes the correction parameters from solely temperature-based to include both internal resistance value and resistance change rate. This parameter expansion allows the correction to account for both steady-state and transient conditions of the sensor element, resolving the contradiction between simple correction processes and accurate gas concentration detection
2Ease of operation
If only the difference between target internal resistance value and actual internal resistance value is used for correction, then the correction is straightforward, but the influence of transitional states is not accounted for
Solution Approach 1:
The patent introduces feedback by continuously monitoring the internal resistance change rate (dRpvs/dt) and using it to dynamically adjust the correction amount. This feedback mechanism ensures that transitional states, where internal resistance is changing, are properly accounted for in the correction process, improving reliability while maintaining reasonable calculation complexity through the use of a structured correction equation
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
Improves the accuracy in detecting gas concentration by considering both static and transitional influences on the concentration detection current, enhancing the precision of gas concentration measurements.
Implementation Method 1
a heater for heating the sensor element
Implementation Method 2
a sensor element including at least one cell having a solid electrolyte body and a pair of electrodes disposed on the solid electrolyte body
Data Source
AI summary
A sensor control apparatus (1) calculates the concentration of oxygen using a gas sensor (3) including a sensor element (11) and a heater (12). The sensor control apparatus (1) repeatedly obtains internal resistance data representing an internal resistance value Rpvs of an oxygen-ion-conductive solid electrolyte body (14) and pump current data representing the value of pump current Ip which flows between a pair of pump electrodes (15) and (16) and whose value varies with the concentration of oxygen. The sensor control apparatus (1) corrects the value of the pump current Ip based on the internal resistance value Rpvs, a target internal resistance value, and a derivative value dRpvs/dt calculated based on a plurality of the repeatedly obtained internal resistance values Rpvs.