Engine Controller Dither Control Filter Temperature Estimation
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Solution Overview
Problem
Existing controllers for internal combustion engines face challenges in accurately estimating filter temperature for effective particulate matter regeneration, particularly when the air-fuel ratio is leaner than the stoichiometric ratio, leading to unstable combustion and reduced temperature increasing performance.
Innovation Solution
A controller configuration that executes a dither control process by varying the air-fuel ratio between cylinders to calculate the filter temperature more accurately, taking into account the difference between lean and rich combustion cylinders and adjusting based on engine load and rotation speed, allowing for precise temperature calculation and enhanced regeneration performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the target air-fuel ratio is set leaner than the stoichiometric ratio to increase oxygen supply for regeneration, then the regeneration efficiency is improved, but the combustion stability deteriorates leading to misfire
Solution Approach 1:
The engine cylinders are divided into two groups: some cylinders operate with lean air-fuel ratio to provide oxygen for regeneration, while other cylinders operate with rich air-fuel ratio to ensure stable combustion and prevent misfire. This segmentation allows simultaneous achievement of regeneration efficiency and combustion stability.
Solution Approach 2:
Different air-fuel ratios are applied to different cylinders based on their functional role. Lean combustion cylinders provide oxygen-rich exhaust for regeneration, while rich combustion cylinders provide stable combustion and fuel for temperature maintenance. Each cylinder has locally optimized air-fuel ratio quality.
2Device complexity
If the filter temperature is estimated based on rotation speed and load, then the estimation process is simple, but the temperature estimation accuracy is low
Solution Approach 1:
The system uses feedback from actual combustion conditions, air-fuel ratio measurements, and engine operating parameters to continuously refine and correct the filter temperature estimation. This feedback mechanism improves accuracy without requiring complex additional hardware.
Solution Approach 2:
The estimation method incorporates multiple varying parameters including air-fuel ratio, rotation speed, load, and combustion stability indicators to dynamically adjust the temperature estimation. This multi-parameter approach significantly improves accuracy over simple rotation-speed-based estimation.
3Quantity of substance
If dither control is executed with target air-fuel ratio leaner than stoichiometric, then oxygen supply for regeneration is increased, but the temperature increasing performance is reduced due to unstable combustion
Solution Approach 1:
Cylinders are segmented into lean-operating cylinders that supply oxygen and rich-operating cylinders that maintain combustion stability and generate heat. This segmentation ensures both oxygen supply and temperature increase are achieved simultaneously.
Solution Approach 2:
The exhaust system effectively combines exhaust gases from lean cylinders (oxygen-rich) and rich cylinders (fuel-rich, high energy) to create a composite exhaust stream that provides both oxygen for regeneration and sufficient thermal energy for temperature maintenance.
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 improves the accuracy of filter temperature calculation and increases the efficiency of the regeneration process by optimizing the air-fuel ratio, ensuring effective particulate matter removal without causing misfire, even when the target air-fuel ratio is leaner than stoichiometric.
Implementation Method 1
a filter configured to trap particulate matter in exhaust gas discharged from cylinders
Implementation Method 2
a dither control process of operating the fuel injection valves such that at least one of the cylinders is a lean combustion cylinder, in which an air-fuel ratio is leaner than a stoichiometric air-fuel ratio, and at least another one of the cylinders is a rich combustion cylinder, in which an air-fuel ratio is richer than the stoichiometric air-fuel ratio
Data Source
AI summary
A controller for an internal combustion engine is configured to execute a dither control process and a filter temperature calculating process. In the dither control process, on condition that an execution request for a regeneration process of the filter is made, fuel injection valves are operated such that at least one of the cylinders is a lean combustion cylinder, and at least another one of the cylinders is a rich combustion cylinder. The filter temperature calculating process is a process of calculating the temperature of the filter to be lower when a target value of an average value of the exhaust air-fuel ratio in a predetermined period by the dither control is leaner than the stoichiometric air-fuel ratio than when the target value is the stoichiometric air-fuel ratio.