Engine Control System Correcting Intake Air During EGR Transients
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Solution Overview
Problem
In internal combustion engines with an EGR mechanism, the amount of intake air does not increase and decrease uniformly with changes in the injection ratio, leading to instability in combustion and increased exhaust emissions, as the air flow meter readings may differ from actual intake air amounts during transient conditions.
Innovation Solution
A control system that includes a first fuel injection valve, a second fuel injection valve, an EGR passage, an EGR valve, and an obtaining unit to determine whether the intake air is increasing or decreasing with respect to the cylinder injection ratio, allowing for correction of the intake air value to maintain accurate measurements and adjust control parameters accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the injection ratio of the first fuel injection valve and the second fuel injection valve changes during transient operation, then the charging efficiency of intake air can be enhanced, but the amount of intake air measured by the air flow meter becomes inaccurate
Solution Approach 1:
The patent introduces a correction value as an intermediary element between the air flow meter measurement and the actual intake air amount. This correction value, calculated based on the injection ratio and its rate of change, compensates for the measurement error caused by transient injection ratio changes, thereby restoring measurement accuracy without sacrificing charging efficiency
Solution Approach 2:
The patent changes the measurement approach by introducing a dynamic correction parameter that accounts for the injection ratio and its rate of change. Instead of relying solely on the air flow meter reading, the system calculates a corrected intake air amount by applying a correction value that varies with operating conditions, thus maintaining accuracy during transient operations
2Device complexity
If control parameters are determined according to the air flow meter reading during transient injection ratio changes, then the control system remains simple, but combustion stability decreases and exhaust emissions increase
Solution Approach 1:
The correction value acts as an intermediary that bridges the simple air flow meter measurement and the reliable control parameter determination. By adding this intermediate calculation step based on injection ratio and its rate of change, the system maintains structural simplicity while significantly improving combustion stability and reducing exhaust emissions
Solution Approach 2:
The system implements feedback by continuously monitoring the injection ratio and its rate of change, then using this information to calculate a correction value that is applied to the intake air amount measurement. This closed-loop approach ensures combustion stability without requiring complex control system modifications
3Adaptability or versatility
If the EGR valve is open during transient operation, then the EGR mechanism functions normally, but the amount of intake air does not change uniformly with injection ratio changes
Solution Approach 1:
The patent addresses the non-uniform intake air change by introducing a dynamic correction parameter that specifically accounts for the interaction between EGR valve opening and injection ratio changes. The correction value is calculated based on both the injection ratio and its rate of change, adapting to the complex gas dynamics in the intake manifold when EGR is active, thus restoring the uniform relationship between injection ratio and intake air amount
Data Source
AI summary
A control system of an internal combustion engine provided with a first fuel injection valve that injects fuel into a cylinder of the internal combustion engine, a second fuel injection valve that injects fuel into an intake port of the internal combustion engine, an EGR passage that introduces an EGR gas from an exhaust passage of the internal combustion engine to an intake passage thereof, an EGR valve that is arranged in the EGR passage, and an obtaining unit that obtains an amount of intake air in the internal combustion engine. When the EGR valve is open, a determination is made as to whether the amount of intake air is in an increasing tendency or in a decreasing tendency with respect to a change in the cylinder injection ratio, and a value of the amount of intake air thus obtained is corrected based on the determination.