EGR Valve Control Using Flow Sensitivity for Precise Gas Flux
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Solution Overview
Problem
Existing exhaust gas recirculation systems in diesel engines face challenges in precisely controlling the flux of recirculated exhaust gas due to variations in engine rotation speed and fuel injection, leading to interference in feedback control and inefficient fuel consumption.
Innovation Solution
The method involves calculating a target mass flux and effective flow area of EGR gas, determining EGR flow sensitivity, and controlling the real opening rate of the EGR valve in real-time based on these calculations to achieve precise control of EGR gas flux, using formulas to determine the target mass flux, effective flow area, and valve opening rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feed forward control method is used to control EGR valve based on engine rotation speed and fuel injection amount, then EGR gas flux can be controlled, but real flowing of EGR gas cannot be reflected and feedback control is interfered in particular conditions
Solution Approach 1:
The patent implements feedback control by using MAF sensor to detect actual intake air flux and comparing it with target intake air flux calculated from engine rotation speed and fuel injection amount. The EGR valve opening rate is adjusted based on the difference between actual and target EGR gas flux, ensuring accurate control even under varying engine conditions. This resolves the contradiction by providing real-time feedback to correct deviations from the feed-forward control predictions.
2Productivity
If EGR valve opening rate is controlled without considering effective flow area and flow sensitivity, then control is simple, but EGR gas flux cannot be controlled precisely and quickly
Solution Approach 1:
The patent calculates target effective flow area and EGR flow sensitivity in advance based on desired EGR gas flux, then uses these pre-calculated parameters to determine the required EGR valve opening rate. This preliminary calculation approach enables quick and precise control response without complex real-time iterations, resolving the contradiction between control speed/precision and system complexity.
3Manufacturing precision
If fixed gain value is used in EGR valve control, then control is simple, but real opening rate of EGR valve cannot be accurately controlled under varying conditions
Solution Approach 1:
The patent implements dynamic gain adjustment where the EGR flow sensitivity (gain value) is continuously updated based on current operating conditions including engine rotation speed, intake air flux, and target EGR gas flux. This dynamic adaptation ensures accurate EGR valve opening control across varying engine conditions, resolving the contradiction between control precision and adaptability.
Data Source
AI summary
An EGR system control method of an engine may include calculating a target mass flux ({dot over (m)}egrd) of EGR gas flowing an EGR line, calculating an effective flowing area (EFA) of an EGR valve disposed on the EGR line, calculating an EGR flow sensitivity by dividing the target mass flux with the effective flowing area, and controlling a real opening rate of the EGR valve by applying the EGR flow sensitivity to a target opening rate of the EGR valve. Accordingly, a gain value is varied on a real time according to an effective flowing area of the EGR valve and a target mass flux of EGR gas such that real opening rate of an EGR valve is accurately and precisely controlled.