EGR Valve Minimum Opening Control for Steady-State
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Solution Overview
Problem
Internal combustion engines face challenges in maintaining optimal exhaust gas recirculation (EGR) valve openings, particularly during steady-state conditions, where the EGR valve may close, leading to inefficiencies and non-compliance with regulations.
Innovation Solution
An engine control system that includes a target air mass module, boost control module, and EGR control module, which sets a predetermined minimum opening for the EGR valve to prevent closure, ensuring it remains open even under steady-state conditions, and adjusts based on changes in air mass over a predetermined period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the EGR valve is allowed to close during steady-state conditions, then the device complexity is reduced, but the reliability and compliance with regulations deteriorate
Solution Approach 1:
The control system performs preliminary action by setting a predetermined minimum opening threshold for the EGR valve before steady-state conditions fully develop. When the target air mass indicates approaching steady-state, the system proactively maintains the EGR valve at this minimum opening rather than allowing it to close completely, thus preventing reliability issues before they occur
Solution Approach 2:
The system changes the control parameter from a dynamic target opening that could reach zero to a constrained parameter with a predetermined minimum opening value. This parameter modification ensures the EGR valve maintains a minimum opening during steady-state conditions, balancing simplicity with reliability and regulatory compliance
2Reliability
If the EGR valve opening is maintained at a predetermined minimum during steady-state, then the reliability and compliance are improved, but the loss of energy increases due to continued exhaust gas recirculation
Solution Approach 1:
The system applies partial action by maintaining only a predetermined minimum opening of the EGR valve rather than keeping it fully open. This limited opening allows sufficient exhaust gas recirculation to maintain reliability and compliance while minimizing the energy loss associated with continuous full-flow recirculation during steady-state conditions
3Productivity
If the EGR valve opening is dynamically adjusted based on target air mass changes, then the productivity and torque control are improved, but the device complexity increases due to additional control logic
Solution Approach 1:
The system implements dynamics by continuously adjusting the EGR valve target opening based on real-time target air mass conditions. The control logic dynamically transitions between different operating modes (normal dynamic control versus minimum opening maintenance) depending on whether the engine is in transient or steady-state conditions, optimizing torque control while managing complexity through conditional logic
Data Source
AI summary
An engine control system includes: a target air mass module configured to determine a target mass of air within a cylinder of an engine based on a torque request; a boost control module configured to control boost provided by a turbocharger based on the torque request; an exhaust gas recirculation (EGR) control module configured to selectively: set a target opening of an EGR valve based on the target mass of air; set the target opening of the EGR valve to a predetermined minimum opening, where the predetermined minimum opening is greater than zero percent open; and control opening of the EGR valve based on the target opening of the EGR valve.