Gas Sensor Control Apparatus Adaptive Current Measurement
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Solution Overview
Problem
As the number of ranks for gas sensors increases, the voltage difference between adjacent ranks decreases, making it difficult to accurately determine the rank of each gas sensor based on its label resistor voltage, thereby reducing the detection accuracy of gas concentration.
Innovation Solution
A sensor control apparatus that supplies a resistance measurement current with multiple designated current values to a characteristic resistor, ensuring the resistor voltage falls within the voltage measurement range, allowing for classification of characteristic resistances and maintaining a sufficient voltage difference between ranks, thus increasing the number of ranks and improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of ranks for gas sensors is increased, then the accuracy in determining the particular-gas concentration characteristic is improved, but the voltage difference between adjacent ranks decreases making rank determination difficult
Solution Approach 1:
The patent changes the parameter of measurement current value adaptively based on the magnitude of characteristic resistance. By selecting between a first measurement current value and a second measurement current value (where the second is smaller than the first), the system maintains optimal voltage differences across all rank levels, enabling accurate rank determination even when the total number of ranks is increased.
2Adaptability or versatility
If the number of ranks is increased, then more gas sensor characteristics can be classified, but the voltage measurement range becomes insufficient to maintain adequate voltage differences
Solution Approach 1:
The patent introduces dynamic adaptability by making the measurement current value variable rather than fixed. The control apparatus dynamically selects between different current values based on the characteristic resistance magnitude, allowing the system to accommodate a larger number of ranks while maintaining reliable voltage differences for accurate rank determination across the extended range.
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 approach enhances the accuracy of gas concentration measurement by maintaining a sufficient voltage difference between ranks, even as the number of ranks increases, thereby improving the overall detection precision.
Implementation Method 1
The sensor control apparatus calculates a characteristic resistance on the basis of a value of a signal generated in response to supply of the resistance measurement current having the designated current value to the characteristic resistor
Data Source
AI summary
A sensor control apparatus controls a gas sensor which measures the concentration of oxygen contained in exhaust gas. A current DA converter of the sensor control apparatus supplies a current having a current value designated by a control section (hereinafter referred to as the designated current value) to a label resistor having a resistance previously set so as to represent the characteristic of the gas sensor (hereinafter referred to as the characteristic resistance). Further, the control section of the sensor control apparatus sets the designated current value to a plurality of values in accordance with the characteristic resistance of the label resistor.