Engine Control Apparatus for Air-Fuel Ratio Sensor Calibration
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Solution Overview
Problem
The output characteristic of air-fuel ratio sensors changes with fuel injection modes, leading to inaccurate estimation of air-fuel ratios and deteriorated exhaust gas properties, particularly under direct injection where hydrogen production increases, affecting the electromotive force and oxygen concentration measurements.
Innovation Solution
An engine controlling apparatus that adjusts fuel injection modes and reference values based on detection signals from air-fuel and oxygen concentration sensors, using feedback control to correct fuel injection amounts and intake air, and includes a selector to switch between injection modes such as MPI+DI single and split injection modes, and MPI injection modes, to maintain a desired air-fuel ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If direct injection mode is used to improve fuel efficiency and power output, then fuel injection rate increases, but air-fuel ratio estimation accuracy deteriorates due to hydrogen production affecting sensor electromotive force
Solution Approach 1:
The patent changes the reference value parameter of the air-fuel ratio sensor according to the injection mode. When direct injection mode is detected, a different reference value is applied compared to port injection mode, compensating for the sensor output shift caused by hydrogen production and maintaining accurate air-fuel ratio estimation across different injection modes
Solution Approach 2:
The patent dynamically switches between different reference values based on the currently active injection mode. The ECU detects which injection mode is in use and automatically selects the appropriate reference value, making the air-fuel ratio estimation system adaptive to changing operating conditions and injection modes
2Productivity
If injection mode is selected based on engine operating conditions, then fuel injection efficiency improves, but sensor output characteristic changes causing deterioration in exhaust gas properties
Solution Approach 1:
The patent adjusts the reference value parameter based on injection mode to compensate for sensor output shifts. This ensures accurate air-fuel ratio control regardless of which injection mode is active, preventing harmful emissions caused by inaccurate air-fuel ratio estimation
Solution Approach 2:
The patent uses feedback control where the ECU continuously monitors the air-fuel ratio sensor output and compares it against the mode-appropriate reference value. Based on the deviation from the target air-fuel ratio, the system adjusts fuel injection to maintain optimal combustion and minimize harmful emissions
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 of air-fuel ratio estimation and exhaust gas properties by adjusting fuel injection modes and reference values, preventing excessive lean or rich air-fuel ratios, thereby reducing NOx and CO emissions.
Implementation Method 1
The linear air-fuel ratio sensor measures the electromotive force generated by oxygen ions traveling in the solid electrolyte and estimates the air-fuel ratio corresponding to the oxygen concentration in exhaust gas
Implementation Method 2
the hydrogen ions infiltrate in the solid electrolyte and reduce the electromotive force generated in the solid electrolyte
Data Source
Figure 1~2
Figure 3A~4B
Figure 5
AI summary
The engine controlling apparatus (1) includes a selector (2) and a changer (3). The selector (2) selects one of a plurality of injection modes according to the operating condition of an engine (10), where injection rates of a plurality of injectors (6, 7) differ among the injection modes. The changer (3) changes a map specifying a reference value of a detection signal detected by a first sensor according to the injection mode.