Air-Fuel Ratio Calculation Device Cold Shoot Correction
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Solution Overview
Problem
The cold shoot phenomenon in air-fuel ratio sensors, where the output value deviates to a rich side, leads to decreased calculation accuracy of the air-fuel ratio, affecting engine control and emissions.
Innovation Solution
An air-fuel ratio calculation device that includes an acquisition unit, an impedance calculation unit, an electric power calculation unit, and an air-fuel ratio calculation unit, which adjusts the calculated air-fuel ratio based on the sensor element's impedance and integrated electric power value to mitigate the cold shoot phenomenon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the heater heats the sensor element to activation temperature, then the sensor element reaches operational temperature, but the cold shoot phenomenon causes output value deviation to rich side
Solution Approach 1:
The patent changes the parameter of air-fuel ratio calculation by introducing correction based on impedance and integrated electric power value. When the sensor element temperature is below activation temperature, the system calculates corrected air-fuel ratio using the formula: corrected air-fuel ratio = calculated air-fuel ratio - correction value, where the correction value is determined by impedance and integrated electric power value parameters.
Solution Approach 2:
The patent replaces direct reliance on raw sensor output with a computational correction system. Instead of mechanically adjusting the heater control, the system uses electrical parameter measurements (impedance and integrated electric power value) to computationally correct the air-fuel ratio calculation, substituting physical adjustment with mathematical correction.
2Temperature
If the heater is energized continuously, then the sensor element maintains activation temperature, but the integrated electric power value increases causing over-correction
Solution Approach 1:
The patent implements feedback control by continuously monitoring the integrated electric power value and using it to adjust the correction amount. The system calculates the integrated electric power value based on heater voltage and duty ratio, then uses this value to determine the appropriate correction amount, creating a closed-loop feedback mechanism that prevents over-correction.
Solution Approach 2:
The patent introduces dynamic adjustment of the correction amount based on real-time electrical parameters. The correction value is not fixed but dynamically calculated based on the integrated electric power value and impedance, allowing the system to adapt the correction magnitude to current operating conditions and prevent over-correction.
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 suppresses the decrease in calculation accuracy of the air-fuel ratio, improving engine control and reducing the risk of deteriorated emissions and drivability.
Implementation Method 1
a heater to heat the sensor element
Implementation Method 2
an output value of a sensor element of an air-fuel ratio sensor, which includes the sensor element placed in an exhaust passage
Data Source
AI summary
An air-fuel ratio calculation device is applied to an air-fuel ratio sensor including a sensor element installed in an exhaust passage of an engine and a heater for heating the sensor element. The air-fuel ratio calculation device includes an acquisition unit, an impedance calculation unit, an electric power calculation unit, and an air-fuel ratio calculation unit.