Spark Timing Control via Residual Gas Mass Prediction
Solution Overview
Problem
Conventional spark ignition engines face challenges in accurately calibrating spark timing due to the lack of direct measurement of internal residual gas mass, which affects fuel efficiency, torque, and emissions, and existing prediction models are either computationally complex or inaccurate, neglecting dynamic pressure waves and volumetric efficiency.
Innovation Solution
A computer-implemented method determines spark timing based on a combustion phasing target using a model that incorporates laminar flame speed, residual gas mass, and turbulent intensity, with a two-step turbulence intensity model and a residual gas fraction prediction model that accounts for dynamic pressure waves and engine operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If physics-based energy balance residual gas calculation methods are used, then accuracy is improved, but on-board processing requirements increase
Solution Approach 1:
The patent segments the complex physics-based calculation into two distinct components: a crank angle resolved component for accurate combustion phasing prediction and a simplified component for real-time control implementation. This segmentation allows the system to maintain high accuracy while reducing computational burden on the engine controller.
Solution Approach 2:
The patent introduces an intermediary approach by using a simplified residual gas mass calculation that serves as a bridge between the complex physics-based model and the real-time control system. This intermediary model captures the essential dynamics without requiring full physics-based computational resources.
2Device complexity
If conventional semi-empirical approaches are used, then computational complexity is reduced, but accuracy deteriorates due to neglecting dynamic pressure waves
Solution Approach 1:
The patent changes the key parameter from residual gas fraction to residual gas mass, which inherently accounts for volumetric efficiency variations and dynamic pressure wave effects. This parameter change allows the model to maintain simplicity while improving accuracy across different operating conditions.
3Loss of time
If map-based spark timing control is used, then calibration time and resources are reduced, but control accuracy deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the simplified residual gas mass calculation continuously informs spark timing adjustments. This feedback loop enables the system to adapt to changing operating conditions in real-time, maintaining high control accuracy without requiring extensive calibration maps.
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 allows for accurate and efficient spark timing control, optimizing combustion phasing while minimizing engine knocking and cycle-to-cycle variations, thereby improving fuel efficiency and reducing emissions.
Implementation Method 1
The spark timing is determined based at least in part on a combustion phasing prediction model determined based at least in part on at least one of laminar flame speed, residual gas mass, or turbulent intensity.
Implementation Method 2
The spark timing is determined based at least in part on a combustion phasing prediction model determined based at least in part on at least one of laminar flame speed, residual gas mass, or turbulent intensity.
Data Source
AI summary
Systems and methods of controlling operation of a vehicle engine are provided. For instance, one example aspect of the present disclosure is directed to determining a spark timing associated with a combustion engine. For instance, a combustion phasing target to be implemented by a combustion engine can be received. A spark timing associated with the combustion engine can be determined based at least in part on the combustion phasing target. The spark timing can be determined based at least in part on an optimization comprising one or more iterations determined during an engine cycle. The spark timing is determined based at least in part on a combustion phasing prediction model determined based at least in part on at least one of laminar flame speed, residual gas mass, or turbulent intensity.