Charge Air Cooler Condensate 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 or inaccurate, leading to ongoing issues with condensate build-up and ingestion during acceleration.
Innovation Solution
A method involving an oxygen sensor positioned downstream of the charge air cooler to determine water storage, allowing the engine controller to adjust engine actuators to decrease condensate formation, evacuate condensate, and increase combustion stability by modulating cooling efficiency and purging routines based on water storage values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the cooling efficiency of the CAC is decreased to reduce condensate formation, then condensate formation is reduced, but condensate still builds up over time causing engine misfire
Solution Approach 1:
The patent employs feedback control by continuously monitoring oxygen sensor readings downstream of the CAC and using this information to dynamically adjust engine actuators. The controller compares actual oxygen levels with expected values and modulates cooling efficiency and purging routines accordingly, creating a closed-loop system that adapts to changing condensate conditions rather than using fixed cooling rates
Solution Approach 2:
The system performs preliminary actions by proactively evacuating condensate from the CAC before it reaches problematic levels. The oxygen sensor detects early signs of condensate accumulation, triggering purging routines that remove water storage in advance, preventing the condensate build-up that would otherwise lead to engine misfire during acceleration
2Reliability
If engine actuators are adjusted to increase combustion stability during condensate ingestion, then combustion stability is improved, but inaccurate parameters lead to ongoing misfire issues
Solution Approach 1:
The patent replaces direct mechanical measurement of water storage with an indirect sensing approach using oxygen sensors. Instead of attempting to measure water content directly, the system uses oxygen level measurements downstream of the CAC as a proxy indicator, substituting a complex measurement problem with a simpler, more reliable sensing method that still provides sufficient precision for control purposes
3Device complexity
If mass air flow rate and condensate amount are used to estimate water in charge air, then estimation is simplified, but accuracy is insufficient to prevent misfire
Solution Approach 1:
The patent introduces an intermediary measurement approach by using oxygen sensor readings as a mediator between the CAC water storage and engine control. Rather than directly measuring water content or relying solely on mass air flow calculations, the oxygen sensor provides an intermediate signal that correlates with water storage conditions, enabling more accurate estimation without requiring direct water measurement
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 and minimizes engine misfire and combustion instability by accurately monitoring and managing water storage in the charge air cooler, enhancing engine operation stability.
Implementation Method 1
an oxygen sensor positioned downstream of the charge air cooler
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 and ambient humidity. Further, 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.