Charge Air Cooler Condensation Estimation Using Oxygen Sensor
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Solution Overview
Problem
Turbocharged and supercharged engines face issues with engine misfire and combustion instability due to condensate formation in the charge air cooler (CAC), which existing methods fail to fully address, especially under humid or rainy conditions and with low-pressure exhaust gas recirculation (EGR) increasing water vapor concentrations.
Innovation Solution
A method that adjusts engine actuators based on water storage at the CAC, using an oxygen sensor positioned downstream of the CAC, ambient humidity, and EGR flow measurements to determine the water accumulation rate, allowing for reduced condensate formation and evacuation of condensate from the CAC, thereby stabilizing combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the cooling efficiency of the CAC is decreased to reduce condensate formation, then condensate formation is reduced, but the CAC cannot remove excess heat effectively
Solution Approach 1:
The patent dynamically adjusts CAC cooling efficiency based on real-time condensate storage estimates. The system varies cooling efficiency between different operating states (high efficiency when condensate is low, reduced efficiency when condensate risk is high) rather than maintaining a fixed cooling level, thus resolving the contradiction between heat removal and condensate prevention
Solution Approach 2:
The system changes the cooling efficiency parameter of the CAC based on detected conditions. By adjusting the cooling parameter dynamically according to ambient humidity, temperature, and condensate storage estimates, the system optimizes both heat removal effectiveness and condensate formation prevention
2Stability of the object's composition
If engine actuators are adjusted to increase combustion stability during condensate ingestion, then combustion stability improves, but engine power may be reduced
Solution Approach 1:
The system performs preliminary actions to prevent condensate ingestion by estimating water storage in the CAC ahead of time. By proactively adjusting CAC cooling efficiency or triggering condensate evacuation before significant condensate accumulation occurs, the system avoids the need for combustion stability corrections, thereby maintaining both power and stability
Solution Approach 2:
The system uses feedback from oxygen sensors and environmental sensors to continuously monitor conditions indicative of condensate formation. This feedback loop enables real-time adjustments to CAC operation or engine actuators only when necessary, optimizing the balance between combustion stability and engine power
3Device complexity
If existing water storage estimation methods are used, then estimation is simple, but accuracy deteriorates when EGR is flowing
Solution Approach 1:
The patent introduces an intermediary approach by using oxygen sensor readings as a proxy indicator for water vapor concentration in the CAC. Since direct water measurement is difficult, the oxygen sensor serves as an intermediary measurement tool that indirectly indicates condensate formation trends, maintaining simplicity while improving accuracy under EGR conditions
Solution Approach 2:
The system uses oxygen sensor data in combination with environmental sensors and EGR flow information to partially compensate for the limitations of any single measurement method. By aggregating multiple partial indicators, the system achieves more accurate water storage estimation without requiring complex direct measurement equipment
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
This approach effectively reduces condensate formation in the CAC and decreases engine misfire and combustion instability by accurately estimating water storage and adjusting engine operations accordingly, even during EGR flow.
Implementation Method 1
the oxygen sensor may be used to determine an amount of water exiting the CAC
Implementation Method 2
Condensate may form in the CAC when the ambient air temperature decreases, or during humid or rainy weather conditions, where the intake air is cooled below the water dew point
Data Source
AI summary
Methods and systems are provided for estimating water storage in a charge air cooler (CAC). In one example, an amount of water accumulating in the CAC may be based on an output of an oxygen sensor positioned downstream of the CAC, ambient humidity, and EGR flow while EGR is flowing. Additionally, engine actuators may be adjusted to purge condensate from the CAC and/or reduce condensate formation based on the amount of water inside the CAC.