Variable-Displacement Engine Combustion Recipes for Torque Transitions
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Solution Overview
Problem
Current variable displacement controlled engines struggle to adjust the charge for different skip fire fractions while maintaining optimal engine performance, efficiency, and emissions during torque output transitions.
Innovation Solution
A method and system for optimizing the combustion recipe by adjusting the mixture of Exhaust Gas Recirculation (EGR) and fresh air, including their compression and cooling, to match the desired torque output during firing fraction transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the engine operates at a different firing fraction while maintaining the same torque output, then the fuel per cylinder can be controlled easily, but the charge mixture must be adjusted to provide optimal performance, efficiency, and emissions
Solution Approach 1:
The system dynamically adjusts the charge mixture composition (EGR rate, fresh air amount, compression degree) based on the current firing fraction to optimize engine performance. The charge parameters are made variable rather than fixed, allowing the engine to adapt to different operating conditions while maintaining optimal combustion characteristics.
Solution Approach 2:
The invention changes the parameters of the charge mixture (EGR rate, fresh air amount, compression degree) according to the firing fraction. By modifying these physical and chemical parameters of the intake charge, the system achieves optimal combustion performance, fuel efficiency, and emissions control for each specific firing fraction while maintaining the desired torque output.
2Productivity
If the charge is optimized for each firing fraction, then engine performance and efficiency improve, but the complexity of the control system increases
Solution Approach 1:
The control system is designed to universally manage multiple charge parameters (EGR rate, fresh air amount, compression degree) through a single integrated control architecture. This multi-functional approach allows the system to optimize performance across different firing fractions without requiring separate control mechanisms for each parameter, thereby managing complexity while maintaining high engine efficiency.
Solution Approach 2:
The system employs feedback control to continuously monitor engine performance and adjust the charge mixture parameters accordingly. By using feedback from sensors and performance data, the control system can automatically optimize combustion for each firing fraction without requiring complex manual intervention or overly sophisticated control algorithms, achieving high efficiency with manageable system complexity.
3Device complexity
If the same charge is used across different firing fractions, then the control system remains simple, but engine performance and emissions are suboptimal
Solution Approach 1:
The system modifies the charge mixture parameters (EGR rate, fresh air amount, compression degree) based on the firing fraction to optimize combustion and reduce emissions. By changing these parameters appropriately for each operating condition, the invention achieves lower harmful emissions and improved engine performance without requiring excessively complex control systems.
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
Improves engine performance, reduces fuel consumption, and controls aftertreatment system temperatures while minimizing harmful emissions.
Implementation Method 1
fresh air which may or may not be compressed by a turbo system
Implementation Method 2
a mix of (a) recirculated exhaust gas from the EGR system as controlled by a position of an EGR valve
Implementation Method 3
a fuel injection strategy, such as number of injection pulses and start of injection timing of each pulse
Data Source
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AI summary
A system and method for transitioning a firing fraction of a variable displacement internal combustion engine when generating a desired torque output. During and following the transition to the second firing fraction, a combustion recipe is ascertained and used operating the cylinders of the variable displacement internal combustion engine to generate the desired torque output. The recipe is preferably optimized for the engine operating at the second firing fraction, at least relative to the previous charge of the previous combustion recipe used with the first firing fraction.