Charge Air Cooler Condensation Estimation via Oxygen Sensor
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Solution Overview
Problem
Turbocharged and supercharged engines face engine misfire and combustion instability due to condensate ingestion from charge air coolers, as existing methods to reduce condensate formation are incomplete and inaccurate, leading to continued build-up and ingestion during acceleration.
Innovation Solution
A method using oxygen sensors positioned at the outlet and inlet of the charge air cooler to determine water storage parameters, adjusting engine actuators based on water content in the charge air exiting the cooler, including adjusting spark timing and purging condensate to maintain combustion stability.
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 condensate may still build up over time and cause engine misfire during acceleration
Solution Approach 1:
The system continuously monitors condensate levels in the CAC using sensors and adjusts engine operating parameters in real-time based on the feedback. When condensate levels exceed a threshold, the controller modifies parameters such as ignition timing, fuel injection, or airflow to prevent engine misfire, creating a closed-loop control system that dynamically responds to condensate accumulation.
Solution Approach 2:
The system detects condensate buildup before it reaches levels that would cause engine misfire. By monitoring condensate levels continuously and taking preliminary corrective actions when thresholds are approached, the system prevents misfire conditions from occurring during acceleration events.
2Reliability
If engine actuators are adjusted to increase combustion stability during condensate ingestion, then combustion stability improves, but the system complexity increases
Solution Approach 1:
The controller utilizes existing engine actuators and control systems for multiple functions: normal engine operation control, condensate level monitoring response, and combustion stability maintenance. By integrating condensate management into the existing actuator control framework, the system avoids adding separate dedicated systems while still achieving reliable combustion stability during condensate ingestion.
3Device complexity
If mass air flow rate and amount of condensate in the CAC are used to determine water in charge air, then the measurement approach is simple, but the parameters do not accurately reflect the amount of water in the charge air exiting the CAC
Solution Approach 1:
The system introduces additional measurement intermediaries such as capacitive sensors or optical sensors positioned at strategic locations to directly detect water content in the charge air exiting the CAC. These intermediaries provide accurate real-time measurements of actual water content, enabling precise control decisions based on the true state of the charge air rather than indirect estimates.
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 engine misfire and combustion instability by accurately measuring and managing condensate levels, ensuring stable engine operation during condensate ingestion.
Implementation Method 1
The oxygen sensor may be operated in either a variable voltage mode or a base mode based on exhaust gas recirculation (EGR) flow. For example, if EGR flow is greater than a threshold, the oxygen sensor may operate in the variable voltage mode to measure oxygen content of the charge air at the outlet of the CAC. The amount of water in the charge air exiting the CAC may then be determined based on a pumping current of the oxygen sensor.
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 in charge air exiting the CAC may be based on an output of an oxygen sensor positioned downstream of the CAC. Further, engine actuators may be adjusted to increase combustion stability and/or reduce condensate formation based on the amount of water exiting the CAC.