EGR Valve Control for Low-Temperature Intake Condensation
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Solution Overview
Problem
EGR gas recirculation can lead to condensation of moisture in the intake passage due to low intake air temperature, potentially causing misfire when introduced into the combustion chamber.
Innovation Solution
An exhaust gas recirculation system that includes an intake air temperature sensor to detect intake air temperature and control EGR valve operation based on predefined temperature and flow rate conditions, prohibiting EGR control when intake air temperature is low and flow rate is insufficient to prevent condensation accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EGR control is executed to recirculate EGR gas into the intake passage, then engine performance is improved by reducing combustion temperature, but moisture in the EGR gas condenses in the intake passage when intake air temperature is low, causing misfire
Solution Approach 1:
The controller changes the operational parameters of the EGR system by monitoring intake air temperature and intake air flow rate. When the intake air temperature is below the first set temperature and the intake air flow rate is below the set flow rate, the controller prohibits EGR control to prevent condensation. This dynamic parameter adjustment resolves the contradiction by adapting EGR operation to environmental conditions.
Solution Approach 2:
The system employs feedback control through the intake air temperature sensor and flow rate monitoring to continuously assess operating conditions. The controller uses this feedback information to make real-time decisions about EGR valve operation, enabling the system to prevent condensation while maintaining performance when conditions are favorable.
2Reliability
If EGR control is prohibited when intake air temperature is low and flow rate is low, then condensation accumulation and misfire are prevented, but engine performance improvement through EGR is lost
Solution Approach 1:
The EGR control system transitions from a static on/off control to a dynamic control that continuously adapts to changing operating conditions. The controller dynamically adjusts EGR valve operation based on real-time intake air temperature and flow rate measurements, enabling the system to optimize both reliability and productivity under varying conditions.
Solution Approach 2:
The system changes the operational state of the EGR valve based on parameter thresholds. When intake air temperature exceeds the first set temperature or intake air flow rate exceeds the set flow rate, the controller permits EGR control to restore performance benefits while maintaining reliability protection.
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
Prevents condensation accumulation in the intake passage by controlling EGR gas recirculation, thereby avoiding misfire and maintaining engine performance.
Implementation Method 1
an intake air temperature sensor that detects an intake air temperature as a temperature of the intake air
Implementation Method 2
when a temperature of an intake air, which is air flowing through the intake passage, is low, due to the low temperature of the intake passage and a small saturated water vapor amount of the intake air, moisture in the EGR gas is condensed in the intake passage
Data Source
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AI summary
An EGR passage 41 and an EGR valve 43 that opens/closes the EGR passage 41 to change an EGR amount as an amount of EGR gas to be recirculated to an intake passage 20 are provided. When an engine E is operated in an EGR region A1, EGR control is executed to recirculate the EGR gas by opening the EGR valve 43. In addition, in the case where an intake air temperature detected by an intake air temperature sensor SN3 is lower than a predetermined first set temperature, the EGR control is prohibited even when the engine E is operated in the EGR region A1 under a condition that an intake air flow rate as a flow rate of intake air flowing through the intake passage 20 is lower than a predetermined set flow rate.