Model-Based Diesel Controller for Auto-Ignition Optimization
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Solution Overview
Problem
Diesel engines operating in alternative combustion modes face challenges with cylinder-to-cylinder and cycle-to-cycle variations in auto-ignition timing, leading to potential engine knock or power loss due to temperature and airflow differences across cylinders, which existing control strategies struggle to manage effectively.
Innovation Solution
A model-based control strategy that uses processor-controlled fuel and valve actuation systems to manage air and fuel intake, adjusting intake valve closing and fuel injection timing to maintain optimal effective compression ratio and temperature, thereby minimizing auto-ignition variations and ensuring robust ignition timing across all cylinders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If fuel is injected early to allow homogeneous mixing, then combustion completeness improves and soot reduces, but auto-ignition timing becomes difficult to control and cycle-to-cycle variations increase
Solution Approach 1:
The system dynamically adjusts multiple parameters including intake valve closing timing, fuel injection timing, and fuel injection quantity to control the effective compression ratio and in-cylinder temperature. This enables precise control of auto-ignition timing while maintaining homogeneous charge conditions that reduce soot formation.
Solution Approach 2:
The control system uses feedback from cylinder pressure sensors and crank position sensors to continuously monitor combustion characteristics and adjust fuel injection and valve actuation parameters in real-time, reducing cycle-to-cycle variations in auto-ignition timing.
2Power
If compression ratio is increased to advance auto-ignition timing, then power output improves, but in-cylinder temperature increases causing engine knock and potential damage
Solution Approach 1:
The system dynamically adjusts the effective compression ratio by varying intake valve closing timing and fuel injection parameters in real-time, allowing the engine to operate at higher effective compression ratios when needed for power while preventing knock through active control of ignition timing and charge temperature.
Solution Approach 2:
The control system performs preliminary adjustment of intake valve closing timing and fuel injection parameters before combustion occurs, preparing the charge conditions to achieve desired auto-ignition timing without excessive temperature rise that would cause knock.
3Power
If intake valve closes earlier to increase effective compression ratio, then auto-ignition timing advances and power improves, but in-cylinder temperature increases leading to higher NOx emissions
Solution Approach 1:
The system coordinates changes in multiple parameters including intake valve closing timing, fuel injection timing, and fuel quantity to achieve the desired effective compression ratio while controlling in-cylinder peak temperature through EGR rate adjustment and injection strategy, thereby reducing NOx emissions while maintaining power output.
4Ease of manufacture
If existing control strategies are used, then implementation is simple, but cylinder-to-cylinder and cycle-to-cycle variations in auto-ignition timing cannot be effectively managed
Solution Approach 1:
The control system implements cylinder-specific control strategies that account for individual cylinder characteristics and operating conditions, adjusting fuel injection and valve actuation parameters for each cylinder to compensate for variations and achieve consistent auto-ignition timing across all cylinders.
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 reduces engine-out emissions, enhances engine performance, and maintains desired torque production by synchronizing auto-ignition with engine speed, while being cost-effective and adaptable to existing electronic engine control systems.
Implementation Method 1
the increasing compression of the charge by the upstroking piston creates sufficiently large temperature to cause auto-ignition of the charge near or at top dead center (TDC)
Implementation Method 2
Auto-ignition may occur as the substantially simultaneous spontaneous combustion of vaporized fuel at various locations within the mixture
Data Source
Figure 1
Figure 2~4
Figure 3
AI summary
A diesel engine (10) operates by alternative diesel combustion. Formation of fuel and charge air mixtures is controlled by processing a particular set of values for certain input data according to a predictor algorithm model (50) to develop data values for predicted time of auto-ignition ?AI and resulting torque TQAI , and also develop data values for control of fuel and air that will produce the predicted time of auto-ignition ?AI and resulting torque TQAI. The data values developed by the predictor algorithm and data values for at least some of the input data are processed according to a control algorithm (52) that compensates for any disturbance dIMT, dEGR introduced into any of the data values for at least some of the input data being processed by the control algorithm. This causes the systems to be controlled by compensated data values IVC, Mf that produce predicted time ?AI of auto-ignition and resulting torque TQAI in the presence of any such disturbance dIMT, dEGR.