Direct Injection Engine Combustion Control via Cylinder Pressure Feedback
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Solution Overview
Problem
Existing engine control systems face challenges in efficiently warming a catalyst to lightoff temperature while minimizing the risk of misfire during catalyst lightoff events, as excessive spark retard can lead to combustion instability and hydrocarbon emission reduction is limited.
Innovation Solution
A combustion control system that determines mean effective pressure (MEP) and coefficient of variation (COV) for engine cylinders, using these metrics to selectively adjust spark timing and fuel injection timing for subsequent combustion events, allowing for faster catalyst warming without inducing misfire.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spark timing is retarded excessively during catalyst lightoff events, then catalyst warming efficiency is improved, but combustion stability deteriorates leading to misfire
Solution Approach 1:
The system dynamically adjusts spark timing based on real-time combustion quality assessment. Instead of using a fixed retarded spark timing during catalyst lightoff events, the control module continuously monitors combustion parameters and adjusts spark timing dynamically to maintain optimal balance between catalyst warming efficiency and combustion stability, preventing misfire while maximizing warming rate.
Solution Approach 2:
The system implements feedback control by monitoring combustion quality metrics (such as cylinder pressure, temperature, and combustion duration) and using this information to adjust spark timing for subsequent combustion events. This closed-loop control ensures that spark timing is retarded enough to promote catalyst warming but not so much that combustion stability is compromised.
2Reliability
If spark timing is advanced to maintain combustion stability, then misfire risk is reduced, but catalyst warming speed decreases
Solution Approach 1:
The system employs dynamic spark timing adjustment rather than static advance or retard. Spark timing is continuously optimized based on real-time combustion assessment, allowing the system to advance timing when stability is at risk and retard timing when warming efficiency can be improved, achieving optimal balance adaptively throughout the catalyst lightoff process.
Solution Approach 2:
The system changes spark timing parameters dynamically based on combustion quality metrics. By monitoring parameters such as cylinder pressure rise rate, combustion duration, and temperature, the control module adjusts spark timing parameters in real-time to maintain combustion stability while maximizing catalyst warming efficiency during lightoff events.
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 system effectively warms the catalyst to lightoff temperature while preventing misfire by dynamically adjusting spark timing and fuel injection based on COV, resulting in reduced hydrocarbon emissions and improved engine stability.
Implementation Method 1
determining a mean effective pressure (MEP) for a first combustion event of a cylinder based on cylinder pressure measured by a cylinder pressure sensor during the first combustion event
Implementation Method 2
Combustion of the air/fuel mixture produces torque and exhaust gas. Torque is generated via heat release and expansion during combustion of the air/fuel mixture
Data Source
AI summary
A combustion control system for a direct injection engine includes a mean effective pressure (MEP) determination module, a coefficient of variation (COV) determination module, a spark timing module, and a fuel control module. The MEP determination module determines a MEP for a first combustion event of a cylinder based on cylinder pressure measured by a cylinder pressure sensor during the first combustion event. The COV determination module determines a COV for the cylinder based on the MEP. The spark timing module selectively sets a spark timing for a second combustion event of the cylinder based on the COV. The second combustion event is after the first combustion event. The fuel control module that selectively provides fuel for the second combustion event based on the COV.