EGR Rate Control via Intake Oxygen Feedback
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Solution Overview
Problem
Existing exhaust gas recirculation systems face issues with pulsating flows leading to poor mixing of exhaust gas and fresh air, difficulty in measuring mass flow, and interaction between exhaust gas recirculation dynamics and charging pressure, resulting in suboptimal pollutant discharge and temperature control in the intake plenum.
Innovation Solution
An exhaust gas recirculation system with sensors in the intake plenum and exhaust gas system, a controller to adjust the mixing ratio of exhaust gas to fresh air based on sensor signals, and actuators for the exhaust gas return valve, turbocharger geometry, and choke valve, allowing for precise control of the oxygen or carbon dioxide concentration to regulate the inert gas percentage in the intake plenum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If exhaust gas recirculation rate is adjusted based on engine operating state, then pollutant emissions are reduced, but strong pulsating flow occurs leading to poor mixing quality
Solution Approach 1:
The patent implements a feedback control system using oxygen sensors in the intake manifold to measure actual oxygen concentration. The ECU continuously adjusts the EGR valve position based on the difference between measured and target oxygen values, creating a closed-loop control that stabilizes the exhaust gas recirculation rate and eliminates pulsating flow effects.
Solution Approach 2:
The system dynamically changes the EGR rate parameter based on engine operating conditions (load, speed, temperature). The control strategy adjusts target oxygen values and EGR rates according to different operating states, allowing optimal pollutant reduction while maintaining stable mixing quality across varying engine conditions.
2Object-generated harmful factors
If pressure-dependent regulation of exhaust gas recirculation rate is implemented, then pollutant discharge is improved, but strong interaction between exhaust gas recirculation dynamics and charging pressure occurs
Solution Approach 1:
The oxygen feedback control system decouples the complex interaction between EGR dynamics and charging pressure by directly controlling the EGR rate through oxygen concentration measurements. This closed-loop approach simplifies the control problem by focusing on the ultimate goal (oxygen concentration control) rather than managing multiple interacting parameters simultaneously.
3Object-generated harmful factors
If exhaust gas recirculation is used to reduce pollutant emissions, then inert gas percentage increases, but temperature in intake plenum cannot be adjusted independently of charging pressure and exhaust gas mass flow
Solution Approach 1:
The system achieves independent temperature control by dynamically adjusting the EGR rate as a separate control parameter. By using oxygen feedback to determine optimal EGR rates, the system can independently control intake temperature through exhaust gas mixing ratios, decoupling temperature control from charging pressure adjustments.
4Device complexity
If conventional decentralized control algorithms are used for controlling exhaust gas mass flow, then system simplicity is maintained, but control effectiveness is reduced due to strong interaction between exhaust gas recirculation and charging pressure dynamics
Solution Approach 1:
The patent replaces decentralized open-loop control with a centralized closed-loop feedback control system. The oxygen sensors provide real-time feedback to the ECU, which coordinates control of the EGR valve and other system components, significantly improving control effectiveness while maintaining reasonable system complexity through software-based control logic.
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 system stabilizes the mixing ratio in the intake plenum, improves pollutant discharge, and allows independent adjustment of temperature by accurately measuring and controlling the exhaust gas recirculation rate, enhancing engine performance across various operating states.
Implementation Method 1
at least one sensor, arranged in the intake plenum, said sensor providing a signal indicative of an amount of an exhaust gas component
Implementation Method 2
adjusting a mixing ratio of exhaust gas to fresh air in the intake plenum based on said calculated correcting variable
Data Source
AI summary
An exhaust gas recirculation system for an internal combustion engine, which comprises an intake plenum, an exhaust gas system, and a fresh-air feed line and an exhaust gas recirculation line connected to the intake plenum, includes a sensor, arranged in the intake plenum for measuring an amount of an exhaust gas component, and a controller constructed for outputting a correcting variable based on the sensor and adjusting the percentage by mass of inert gas in the intake plenum on the basis of the correcting variable. The sensor arranged in the intake plenum is a gas concentration sensor which is equipped for determining the air ratio, the oxygen concentration or the carbon dioxide concentration in the intake plenum and to output as sensor variable a variable representing the air ratio, the oxygen concentration or the carbon dioxide concentration to controller.