EGR Valve Control via Flow Model Nozzle Area
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Solution Overview
Problem
Traditional EGR control systems for internal combustion engines rely on mass flow sensors, which are prone to calibration issues due to variable intake system configurations and environmental dirt, leading to ineffective NOx reduction, especially in off-road applications, and alternative sensors are expensive and unreliable.
Innovation Solution
A sensorless EGR valve control system using a flow model that calculates the equivalent outflow area of the EGR valve as a nozzle, with a closed-loop control scheme and PID regulator, parameterized by engine revolutions per minute and fuel quantity, to continuously adjust the EGR valve opening based on feedback and error filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mass flow sensor is used for EGR control, then intake air flow measurement is available, but sensor calibration is highly influenced by variable intake system configuration and environmental dirt
Solution Approach 1:
The invention extracts the measurement function from the physical mass flow sensor and implements it through a mathematical model (equation 1) that calculates air flow based on manifold pressure, temperature, and engine parameters. This removes the sensor from the system while preserving the measurement capability through alternative physical principles.
Solution Approach 2:
The mechanical/electrical mass flow sensor is replaced with a computational model based on fundamental thermodynamic and fluid dynamics equations. The system substitutes physical sensing with mathematical calculation using readily available sensor data from the engine management system.
2Reliability
If alternative sensors (Uhego, Soot, NOx, Pitot tube) are used, then EGR control without mass flow sensor is achieved, but these sensors are expensive and have lack of continuous availability
Solution Approach 1:
The system uses existing sensors already present in the engine management system (manifold pressure, temperature, speed, load) to perform EGR control calculations. No additional dedicated sensors are required, as the system serves itself using available data and fundamental physical equations.
Solution Approach 2:
The control unit performs multiple functions: it manages engine operation, monitors existing sensors, calculates air flow through the mathematical model, and controls the EGR valve. This multi-functional approach eliminates the need for specialized single-purpose sensors.
3Ease of operation
If mapping of EGR valve opening is used based on engine speed and load, then EGR control is simplified, but robust control of component drifts due to production uniformity and ageing is not achieved
Solution Approach 1:
The system continuously monitors actual manifold pressure and compares it with the target pressure calculated from the mathematical model. The EGR valve position is adjusted in real-time based on the difference between desired and actual conditions, creating a closed-loop control that compensates for component variations and ageing.
Solution Approach 2:
The control system transitions from static mapping tables to dynamic calculation based on real-time sensor inputs and fundamental physical equations. The mathematical model continuously adapts to current operating conditions, providing robust control that responds to changing system characteristics.
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 approach provides robust and precise EGR control independent of sensor variability and environmental factors, improving NOx reduction and engine management across varying conditions without the need for expensive sensors, while maintaining reliability and cost-effectiveness.
Implementation Method 1
the EGR valve is modelled as a nozzle from which the recirculated gas flow, in order to calculate an outflow area value and to correct the recirculated gas flow rate according to a flow model
Implementation Method 2
the feedback line may be filtered by a regulator, parameterized with respect to the revolutions per minute of the engine
Data Source
Figure 1~2
Figure 3
AI summary
System for controlling an EGR valve of an internal combustion engine based on a flow model (1), the flow model (1) estimating an EGR flow rate (dmEGR_Est) outgoing from the EGR valve to control an opening/closing of said EGR valve, on the basis of operating parameters (p2, p3, T_EGR) of the internal combustion engine; the method being characterized in that it models said EGR valve as a nozzle and it calculates a relative equivalent outflow area (Aeff) to correct said estimation of the EGR flow rate (dmEGR_Est).