Gas Sensor Control Apparatus for Current Regulation
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Solution Overview
Problem
Existing gas sensors face challenges in accurately and efficiently responding to changes in air-to-fuel ratios, particularly due to issues with current value reduction when electromotive force is low, leading to delayed output changes and potential increased NOx emissions.
Innovation Solution
A gas sensor control apparatus with a current conduction regulating device and voltage circuit that induces electric current between electrodes using the electromotive force of the electromotive force cell, and a voltage circuit that increases the electric potential of the exhaust side electrode, ensuring consistent current flow and improved output characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the electromotive force cell is used as a battery to induce electric current flow, then the structure is simplified, but the current value becomes excessively reduced when electromotive force is small
Solution Approach 1:
A current conduction regulating device is introduced as an intermediary component between the electromotive force cell and the load. This device includes a switching element that can selectively connect or disconnect the electromotive force cell from the load based on the electromotive force level, preventing excessive current reduction when voltage is low while maintaining the simplified battery-based structure.
Solution Approach 2:
The system dynamically adjusts the circuit configuration based on the electromotive force level. When the electromotive force is above a threshold, the switching element connects the cell to the load for normal operation. When the electromotive force drops below the threshold, the switching element disconnects the cell to prevent excessive current reduction, thereby maintaining reliable current delivery while keeping the structure simple.
2Adaptability or versatility
If constant current circuit uses PWM control operation, then the output characteristic can be adjusted, but the structure becomes more complex
Solution Approach 1:
The PWM control operation is extracted and replaced with a simpler switching mechanism. Instead of using complex pulse width modulation circuitry, the invention uses a switching element that selectively connects or disconnects the electromotive force cell based on voltage levels, achieving output characteristic adjustment with minimal structural complexity.
Solution Approach 2:
The system uses the electromotive force cell's own voltage level to automatically control the switching element, eliminating the need for external control circuits. The cell essentially controls itself through its voltage threshold, simplifying the overall structure while maintaining the ability to adjust output characteristics.
3Adaptability or versatility
If the electromotive force of the cell is small, then the cell can operate in lean state, but the current value becomes excessively small or cannot be conducted
Solution Approach 1:
The switching element is configured to disconnect the electromotive force cell from the load when the cell voltage drops below a predetermined threshold. This preliminary action prevents the cell from operating in a state where it would produce excessively small or unstable current, thereby maintaining reliable current conduction while allowing the cell to operate across the full range of electromotive forces including lean state conditions.
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 enhances the gas sensor's ability to accurately reflect air-to-fuel ratio changes, reducing NOx emissions by maintaining optimal current values across the electromotive force range and improving the sensor's responsiveness and reliability.
Implementation Method 1
a gas sensor that outputs an electromotive force signal corresponding to an air-to-fuel ratio of exhaust gas of an internal combustion engine and includes an electromotive force cell, which has a solid electrolyte body and a pair of electrodes
Implementation Method 2
induce a flow of an electric current between the exhaust side electrode and the reference side electrode through the solid electrolyte body in the electromotive force cell while using the electromotive force of the electromotive force cell as an electric power source
Implementation Method 3
a voltage circuit that increases the electric potential of the exhaust side electrode by a predetermined amount relative to an electric potential at an output side of the current conduction regulating device
Data Source
AI summary
An O2 sensor has a sensor element, which includes a solid electrolyte layer and a pair of electrodes. The solid electrolyte layer is held between the electrodes, which includes an atmosphere side electrode and an exhaust side electrode. A constant current circuit is installed in an electric path, which connects between the atmosphere side electrode and a ground, to induce a flow of a predetermined constant electric current between the electrodes through the solid electrolyte layer. A voltage circuit is installed in an electric path, which connects between the exhaust side electrode and a ground, to increase an electric potential of the exhaust side electrode by a predetermined amount relative to an electric potential at an output side of the constant current circuit, from which the electric current flows out of the constant current circuit.