EGR Flow Correction via Intercooler Dew Condensation Calculation
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Solution Overview
Problem
Existing internal combustion engine control devices fail to accurately account for dew condensation in the intercooler, leading to underestimation of EGR flow rate and potential abnormal combustion issues like knocking.
Innovation Solution
An internal combustion engine control device that includes a moisture amount calculation unit, a dew condensation calculation unit, and an EGR correction unit to accurately determine the EGR flow rate by accounting for dew condensation in the intercooler, adjusting the EGR valve opening degree to maintain optimal combustion conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the EGR flow rate is estimated based on EGR valve opening degree and differential pressure across the EGR valve, then the EGR flow rate can be calculated, but the actual EGR flow rate flowing into the combustion chamber is smaller than the estimated value due to dew condensation in the intercooler
Solution Approach 1:
The control device calculates the dew condensation generation amount in advance by determining the total moisture amount in the mixed gas (fresh air + EGR gas) and comparing it against the saturated water vapor amount at intercooler conditions. This preliminary calculation allows the system to predict the actual EGR flow rate before combustion occurs, enabling proactive correction of the EGR valve opening degree to maintain accurate EGR flow control despite dew condensation effects
2Loss of energy
If the EGR flow rate is increased to improve fuel efficiency, then fuel consumption decreases, but abnormal combustion such as knocking may occur due to inaccurate EGR flow rate estimation
Solution Approach 1:
The control device uses feedback from the calculated dew condensation generation amount to continuously adjust the EGR valve opening degree. By monitoring the relationship between total moisture amount, saturated water vapor amount, and actual EGR flow rate, the system dynamically corrects the EGR valve positioning to maintain the intended EGR flow rate, thereby preventing abnormal combustion while optimizing fuel efficiency
3Ease of operation
If the EGR valve opening degree is adjusted to control EGR flow rate, then exhaust gas recirculation can be optimized, but dew condensation in the intercooler causes the actual EGR flow rate to differ from the estimated value
Solution Approach 1:
The control device changes the control parameter from the raw EGR valve opening degree to a corrected EGR valve opening degree that accounts for dew condensation effects. By calculating the dew condensation generation amount based on moisture content and temperature conditions, the system adjusts the EGR valve opening degree to compensate for water vapor condensation, thereby maintaining accurate EGR flow rate control despite the physical changes occurring in the intercooler
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
The device effectively corrects the EGR flow rate, preventing abnormal combustion and ensuring stable engine operation by accurately accounting for dew condensation, thereby improving fuel efficiency and reducing the risk of knocking.
Implementation Method 1
when dew condensation occurs in the intercooler, water vapor exceeding the saturated water vapor amount becomes water
Implementation Method 2
an intercooler that cools intake air
Data Source
AI summary
Provided is an internal combustion engine control device capable of appropriately correcting a flow rate of EGR gas. Therefore, an internal combustion engine control device 20 includes moisture amount calculation units 301 and 302, a dew condensation calculation unit 303, and an EGR correction unit 304. The moisture amount calculation unit 301 calculates a total moisture amount contained in the mixed gas. The dew condensation calculation unit 303 calculates a dew condensation generation amount WQcon in an intercooler based on the total moisture amount. The EGR correction unit 304 corrects a flow rate of the EGR gas based on the dew condensation generation amount WQcon.