Engine Combustion Control for Stability During Load Transitions
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Solution Overview
Problem
Conventional engine systems face instability in combustion during transition states due to changes in in-cylinder properties, such as in-cylinder temperature and EGR rate, leading to potential ignition timing issues and increased combustion noise.
Innovation Solution
An engine system with a controller that selectively performs flame propagation combustion and compressed self-ignition combustion, using a spark plug for ignition and adjusting in-cylinder properties through a property adjusting device, to maintain stability by setting a target torque and load based on accelerator opening sensor data, with a delay to match vehicle response to driver input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine performs compressed self-ignition combustion to improve thermal efficiency, then fuel efficiency is improved, but combustion stability deteriorates during transition states due to changes in in-cylinder properties
Solution Approach 1:
The controller predicts future in-cylinder properties based on current accelerator opening and sets target combustion parameters in advance. By performing preliminary action to anticipate transition states, the system maintains combustion stability while preserving the fuel efficiency benefits of compressed self-ignition combustion.
Solution Approach 2:
The system dynamically switches between flame propagation combustion and compressed self-ignition combustion based on predicted in-cylinder properties and transition state detection. This dynamic adjustment allows the engine to maintain optimal fuel efficiency while ensuring combustion stability during transition states.
2Speed
If the engine switches combustion modes rapidly in transition states, then responsiveness to driver input is improved, but combustion noise increases due to improper ignition timing
Solution Approach 1:
The controller predicts future in-cylinder properties and determines optimal combustion mode transitions in advance. This preliminary action ensures that combustion mode switching occurs at appropriate times, maintaining responsiveness while preventing combustion noise by avoiding improper ignition timing during transitions.
Solution Approach 2:
The system uses feedback from accelerator opening sensor and predicted in-cylinder properties to continuously adjust combustion mode selection. This feedback mechanism ensures responsive acceleration while maintaining combustion stability and minimizing noise by adapting to real-time driving conditions.
3Stability of the object's composition
If the engine uses flame propagation combustion for stable combustion, then combustion stability is improved, but thermal efficiency decreases compared to compressed self-ignition combustion
Solution Approach 1:
The system dynamically selects between flame propagation combustion and compressed self-ignition combustion based on operating conditions and predicted in-cylinder properties. This dynamic approach allows the engine to maintain high thermal efficiency during steady-state operation while ensuring combustion stability during transition states.
Solution Approach 2:
The controller changes combustion parameters including ignition timing, fuel injection timing, and combustion mode based on predicted in-cylinder properties. These parameter changes enable the engine to optimize thermal efficiency while maintaining combustion stability across different operating conditions.
4Ease of operation
If the engine responds immediately to accelerator opening, then drivability is improved, but sudden vehicle movements occur causing discomfort to the driver
Solution Approach 1:
The controller predicts future engine load and torque requirements based on current accelerator opening and intermediate accelerator opening values. By performing preliminary action to anticipate driver intent, the system provides smooth acceleration with reduced jerk while maintaining good drivability.
Solution Approach 2:
The system dynamically adjusts torque output and combustion mode transitions based on predicted accelerator operation patterns. This dynamic response smoothing maintains responsive drivability while eliminating sudden vehicle movements that cause driver discomfort.
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 configuration stabilizes combustion during transition states, improves drivability by reducing sudden vehicle movements, and enhances fuel efficiency and emission control performance by switching between combustion modes based on real-time engine load.
Implementation Method 1
flame propagation combustion in which fuel injected into a cylinder from the injector is forcibly ignited using the spark plug
Implementation Method 2
compressed self-ignition combustion in which fuel injected into the cylinder from the injector carries out compressed self-ignition without using the spark plug
Data Source
AI summary
An engine system is provided, which includes a vehicle-mounted engine having an injector, a spark plug, and a property adjusting device, an accelerator opening sensor, and a controller. The controller performs a combustion control for controlling the injector, the spark plug, and the property adjusting device so that a target torque set based on a present accelerator opening detected by the accelerator opening sensor is outputted in a specific cycle in the future from a present time by a given delay time. In the combustion control, the controller sets a target load of the engine in the specific cycle based on the present accelerator opening, and sets a combustion transition from the present cycle to the specific cycle by selecting beforehand combustion from the present cycle to the specific cycle, from flame propagation combustion and compressed self-ignition combustion, based on the set target load.