EGR Valve Flow Control via Learned Feedback
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Solution Overview
Problem
Existing intake and exhaust systems face challenges in controlling the flowrate of exhaust gas recirculation (EGR) due to deposits like soot on the EGR valve, leading to poor fuel efficiency, increased NOx emissions, and degradation of knocking prevention performance.
Innovation Solution
An intake and exhaust system with an EGR channel, an EGR valve, an isolation valve, and an air admittance valve, where a control device learns the relationship between actual and reference flowrates to adjust the EGR valve's opening degree, reflecting the impact of deposits and maintaining optimal EGR flow despite soot accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the EGR valve opening degree is adjusted based on reference flowrate without considering deposits, then the control system is simple, but the actual EGR flowrate becomes inaccurate leading to poor fuel efficiency and increased NOx emissions
Solution Approach 1:
The system introduces feedback by learning the relationship between opening degree and actual EGR flowrate through the air admittance valve. The control device adjusts the opening degree based on learned data that reflects actual flow conditions, compensating for deposit effects and maintaining accurate EGR control despite valve degradation over time.
Solution Approach 2:
The system changes the control parameter from a fixed reference flowrate to a learned relationship between opening degree and actual flowrate. By storing and using learned data that captures the actual flow characteristics under different operating conditions, the system adapts to deposit accumulation and maintains control accuracy.
2Reliability
If the EGR valve opening degree is increased to compensate for deposits, then the EGR flowrate is maintained, but the risk of knocking increases due to excessive EGR
Solution Approach 1:
The feedback mechanism learns the actual EGR flowrate relationship and adjusts the opening degree precisely to achieve the target flowrate without excessive compensation. This prevents knocking by avoiding overly aggressive opening degree adjustments that would occur with simple fixed-ratio compensation methods.
Solution Approach 2:
The system replaces mechanical deposit compensation (fixed opening degree increases) with a learned control model that calculates the precise opening degree needed. This substitution allows for more accurate and adaptive control that prevents both insufficient and excessive EGR, thereby preventing knocking.
3Reliability
If learning processing is implemented to account for deposits, then EGR flowrate control accuracy is improved, but the device complexity increases
Solution Approach 1:
The control device performs self-learning by automatically acquiring and storing the relationship between opening degree and actual EGR flowrate during normal operation. This self-service approach eliminates the need for external calibration equipment or complex manual adjustment mechanisms, achieving improved control accuracy while keeping the system relatively simple.
Solution Approach 2:
The system performs preliminary learning processing to establish the opening degree-flowrate relationship before normal control operations. By pre-acquiring this data and storing it in memory, the system prepares the necessary control information in advance, enabling accurate EGR control without requiring complex real-time calculations during operation.
Data Source
AI summary
An intake and exhaust system includes an engine, an intake air channel, an exhaust gas channel, an EGR channel, an EGR valve, and a control device. By adjusting an opening degree of the EGR valve, the control device executes EGR control processing to control a flowrate of a recirculating exhaust gas. An isolation valve is disposed in the EGR channel closer to the exhaust gas channel than the EGR valve is. An air admittance valve is disposed in the EGR channel closer to the exhaust gas channel than the EGR valve is and closer to the intake air channel than the isolation valve is. The control device executes learning processing to learn a relationship between an actual flowrate and a reference flowrate while the isolation valve is closed and the air admittance valve is opened. The control device executes the EGR control processing based on a learning processing result.