EGR Control System Transient Fluid Dynamics
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Solution Overview
Problem
Current internal combustion engine exhaust-gas-recirculation systems face challenges in transient fluid-dynamic conditions, leading to inaccuracies in measuring airflow and recirculated gas flow rates, which affect engine performance and NOx emissions.
Innovation Solution
An electronic control system that processes a fluid-dynamic model to estimate 'effective EGR percentage' and 'effective lambda' within the engine, allowing for active regulation of the recirculation system to correct for transient phenomena and optimize gas composition and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional airflow sensors are used in transient fluid-dynamic conditions, then the device complexity is low, but the measurement precision deteriorates due to inaccuracies in measuring airflow and recirculated gas flow rates
Solution Approach 1:
The patent replaces conventional mechanical airflow sensors with a fluid-dynamic model-based estimation system. The control unit calculates effective EGR percentage and effective lambda by processing signals from existing sensors (manifold pressure sensors, temperature sensors, airflow sensors) through fluid-dynamic models, eliminating the need for complex specialized measurement devices while improving accuracy in transient conditions
Solution Approach 2:
The patent introduces a fluid-dynamic model as an intermediary between raw sensor signals and control decisions. The model processes manifold pressure, temperature, and airflow sensor signals to estimate effective EGR percentage and effective lambda, serving as a mediator that translates basic sensor data into accurate flow rate measurements without requiring direct complex measurement hardware
2Reliability
If active regulation of the recirculation system is implemented to correct transient phenomena, then the measurement precision and control accuracy improve, but the device complexity increases due to additional processing requirements
Solution Approach 1:
The patent implements feedback control by continuously monitoring manifold pressure, temperature, and airflow, comparing estimated effective EGR percentage and effective lambda against target values, and adjusting the recirculation valve accordingly. This closed-loop feedback mechanism improves control accuracy and reliability while using standard control unit functionality
Solution Approach 2:
The patent makes the control unit multi-functional by having it perform both standard engine control functions and fluid-dynamic model processing for EGR estimation. The same control unit that manages fuel injection and ignition timing also processes manifold pressure and temperature signals through fluid-dynamic models to calculate effective EGR percentage, eliminating the need for separate dedicated control hardware
3Measurement precision
If fluid-dynamic models are processed to estimate effective EGR percentage and lambda, then the measurement precision of gas composition improves, but the loss of time increases due to computational processing requirements
Solution Approach 1:
The patent performs preliminary action by pre-calculating and storing fluid-dynamic model parameters and characteristics in the control unit's memory before transient conditions occur. During transient operations, the control unit retrieves and applies these pre-prepared models to estimate effective EGR percentage and effective lambda, significantly reducing computational processing time compared to real-time calculation from scratch
Solution Approach 2:
The patent applies dynamics by using adaptive fluid-dynamic models that adjust their parameters based on current operating conditions. The control unit modifies model parameters in real-time according to engine load, speed, and temperature conditions, allowing accurate gas composition estimation while minimizing processing time through condition-specific model selection rather than universal complex calculations
Data Source
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AI summary
In an internal-combustion engine with exhaust-gas-recirculation system, electronic control means are provided designed to process an analytical model of the quantities "effective lambda" and effective EGR percentage", which is constructed on the basis of the physical laws that regulate the fluid-dynamic conditions in the intake pipe, in the exhaust pipe, and in the recirculation pipe of the engine. On the basis of the deviation between the values of said quantities estimated by the model and the reference values of said quantities associated to the conditions of operation of the engine, an operation of correction on the control of the valve that governs the recirculation circuit is implemented.