EGR Controller Feedback Control for Exhaust Gas Accuracy
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Solution Overview
Problem
Conventional EGR systems face challenges in achieving high control accuracy and stability for the quantity of recirculated exhaust gas flowing into a cylinder, which is essential for improving fuel economy and reducing emissions.
Innovation Solution
An EGR controller that includes measuring and estimating means to accurately compute the quantity of recirculated exhaust gas, using an intake valve model, EGR valve model, and EGR diffusion model, along with feedback control to adjust the EGR valve opening degree, ensuring precise control of the exhaust gas ratio based on engine driving conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional EGR valve control is used, then the system is simple to operate, but control accuracy and stability of exhaust gas quantity are insufficient
Solution Approach 1:
The patent implements feedback control by measuring the actual exhaust gas quantity flowing into the cylinder and comparing it with the target value, then adjusting the EGR valve opening degree based on the deviation. This closed-loop control system continuously monitors and corrects the exhaust gas quantity, achieving high control accuracy and stability while maintaining reasonable system complexity through the use of established control algorithms.
Solution Approach 2:
The patent replaces direct mechanical control of the EGR valve with an electronic control system that uses sensors, processors, and actuators. This substitution enables more precise control through electronic signal processing and algorithmic decision-making, significantly improving measurement precision and control accuracy while allowing for sophisticated control strategies without proportionally increasing mechanical complexity.
2Measurement precision
If conventional EGR control is used, then the system structure is simple, but the accuracy of estimating exhaust gas quantity is not high
Solution Approach 1:
The patent introduces an intermediary estimation system that uses multiple parameters (intake air quantity, engine speed, load conditions) and mathematical models to calculate the exhaust gas quantity. This intermediary estimation layer acts as a bridge between simple sensor measurements and the required control decisions, providing accurate real-time estimates of exhaust gas quantity flowing into the cylinder without requiring direct measurement of every parameter.
Solution Approach 2:
The control system performs multiple functions using a unified approach: it estimates exhaust gas quantity, compares it with target values, determines control deviations, and adjusts EGR valve opening. This multi-functional integration allows the system to achieve high estimation accuracy while avoiding the complexity of separate dedicated systems for each function, as the same computational resources and sensors serve multiple purposes.
3Measurement precision
If feedback control is implemented to improve control accuracy, then control precision improves, but control stability becomes difficult to achieve
Solution Approach 1:
The patent implements dynamic control by continuously adjusting the EGR valve opening degree based on real-time feedback from exhaust gas quantity measurements. The control system adapts to changing engine operating conditions (speed, load, temperature) by modifying control parameters and target values dynamically. This dynamic approach maintains both precision and stability by responding to actual system state rather than using fixed control settings.
Solution Approach 2:
The feedback mechanism compares actual exhaust gas quantity with target values and adjusts the EGR valve accordingly. By using proportional control based on the deviation magnitude and direction, the system achieves stable convergence to the target value without excessive oscillation. The feedback loop is designed with appropriate gain parameters that balance responsiveness (precision) with system stability.
Data Source
AI summary
By means of an air model, an estimated quantity of an exhaust gas flowing into a cylinder and a target quantity of the exhaust gas are computed. A deviation between the estimated quantity and the target quantity is multiplied by a feedback gain to obtain a feedback correction quantity. A reference opening degree of an EGR valve is defined according to an engine driving condition and the feedback correction quantity is added to the reference opening degree to obtain a command opening degree of the EGR valve. According to the engine driving condition and the deviation between the estimated quantity and the target quantity, a feedback gain is established so that control accuracy and control stability of a feedback control can be ensured.