Air-Fuel Ratio Sensor Voltage Controller Stabilization
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Solution Overview
Problem
Existing air-fuel ratio sensor controllers take time to stabilize and adjust the application voltage to a target value, which is not desirable for efficient control.
Innovation Solution
A controller with a digital processor, D/A converters, operational amplifiers, and a current sensing resistor that uses digital calculations to quickly control the application voltage applied to the air-fuel ratio sensor by adjusting the output voltage based on the sensor current and resistance, allowing for rapid stabilization at a target voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a feedback resistor is provided between the output terminal of the drive circuit and the inverted input terminal of the operational amplifier, then the voltage and current output from the operational amplifiers can be controlled, but it takes time for the application voltage to stabilize to a target value
Solution Approach 1:
The patent extracts the voltage stabilization function from the traditional feedback resistor circuit and implements it separately using a capacitor connected between the output terminal and inverted input terminal of the operational amplifier. This allows the capacitor to independently handle voltage stabilization without interfering with the feedback control function of the resistor, thereby reducing overall stabilization time while maintaining control stability
Solution Approach 2:
The patent introduces a capacitor as an intermediary element between the output terminal and the inverted input terminal of the operational amplifier. This capacitor acts as a mediator that smooths voltage fluctuations and accelerates voltage stabilization to the target value, resolving the contradiction between stable control and fast response
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
Enables the air-fuel ratio sensor to achieve stable and quick control of the application voltage, reducing delays in voltage stabilization and improving the responsiveness of the sensor control.
Implementation Method 1
a first Digital-to-Analog converter that converts a first input digital value input to the D/A converter as an instruction value to an analog value
Implementation Method 2
a first operational (OP) amplifier (i) receiving an analog output voltage from the first D/A converter by an non-inverted input terminal, and (ii) connecting an output terminal of the first OP amplifier to an inverted input terminal
Implementation Method 3
a current sensing resistor being disposed at a position in a voltage application path to the air-fuel ratio sensor... sensing a sensor current (Is) that flows in the air-fuel ratio sensor
Implementation Method 4
an Analog-to-Digital (A/D) converter converting a detected voltage that is detected by the current sensing resistor by an A/D conversion and outputting a digital value
Data Source
AI summary
A controller of an air-fuel ratio sensor includes, in a digital processor, an adjuster and a control unit, among which the adjuster adjusts a second input digital value for a control of an output voltage of a second voltage application circuit to a preset voltage, and the control unit controls, based on a calculation result of a digital value of a sensor current, a first input digital value for a control of an output voltage of an output terminal of a first OP amplifier of a first voltage application circuit to a voltage Vu based on the equation, Vu=Vout±(Vtar+Is×Rs), so that an application voltage applied to the air-fuel ratio sensor is quickly adjusted to a target voltage.