EGR Control System Mass Fraction Calculation
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Solution Overview
Problem
Internal combustion engines face operational issues when the target mixture of exhaust, air, and fuel is not maintained in the exhaust gas recirculation (EGR) system, leading to suboptimal engine performance.
Innovation Solution
An engine control system that includes a flowrate module, mass fraction calculating modules, and an actuator control module to determine and adjust the mass flowrate and mass fractions of recirculated exhaust gas, allowing for selective adjustment of engine operating parameters to achieve a target mixture for each combustion event.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the EGR system recirculates exhaust back to the intake system, then the target mixture of exhaust, air, and fuel can be achieved, but the system complexity increases due to additional control modules and calculation requirements
Solution Approach 1:
The control system is divided into distinct functional modules: a flowrate module that determines exhaust mass flowrate, first and second mass fraction calculating modules that compute different mass fractions, and an actuator control module that adjusts engine parameters. This segmentation allows each module to perform a specific calculation or control function independently, making the complex EGR control system more manageable and maintainable while ensuring reliable engine operation.
2Productivity
If the mass fraction of recirculated exhaust gas is precisely calculated and controlled, then the target mixture is maintained for optimal engine performance, but the computational requirements and control precision demands increase
Solution Approach 1:
The patent introduces intermediate calculated parameters (first mass fraction and second mass fraction) that serve as mediators between the raw sensor data and the final actuator control decisions. The first mass fraction is calculated from the exhaust mass flowrate, and the second mass fraction is derived from averaging the first mass fraction over multiple combustion events. These intermediate calculations break down the complex control task into manageable steps, enabling precise control of the target mixture while optimizing engine performance.
3Productivity
If the EGR flow rate is increased to improve combustion efficiency, then more exhaust is recirculated, but the pressure differential required for exhaust flow back to intake becomes harder to maintain
Solution Approach 1:
The actuator control module uses feedback from the calculated second mass fraction of recirculated exhaust gas to selectively adjust engine operating parameters. This closed-loop feedback control allows the system to dynamically respond to changing conditions, maintaining the optimal balance between EGR flow rate and pressure differential. When the second mass fraction indicates the target mixture is not being maintained, the actuator control module adjusts parameters to correct the deviation, ensuring both combustion efficiency and proper pressure differential are maintained.
Data Source
AI summary
An engine control system for a vehicle includes a flowrate module, first and second mass fraction calculating modules, and an actuator control module. The flowrate module determines a mass flowrate of exhaust gas recirculation (EGR) to an engine. The first mass fraction calculating module, based on the mass flowrate of EGR, determines a first mass fraction of recirculated exhaust gas relative of a first gas charge for a first combustion event of the engine. The second mass fraction calculating module determines a second mass fraction of recirculated exhaust gas of a second gas charge for a second combustion event of the engine based on an average of the first mass fraction and one or more other values of the first mass fraction determined for other combustion events, respectively. The actuator control module selectively adjusts an engine operating parameter based on the second mass fraction.