SICI Combustion Control Device for Engine Noise and Efficiency
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Solution Overview
Problem
Compression autoignition engines face challenges in maintaining fuel economy and reducing combustion noise, particularly when load increases, as autoignition occurs prematurely due to elevated temperatures, limiting the operation region and efficiency of compression ignition.
Innovation Solution
A combustion control device that combines Spark Ignition (SI) and Compression Ignition (CI) modes, where SI combustion initiates flame propagation and CI combustion occurs through autoignition, with controlled fuel injection to manage temperature and reduce noise, using a controller to adjust fuel injection timing and ratio to optimize combustion timing and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the temperature in the combustion chamber is increased to improve combustion efficiency, then fuel economy is improved, but autoignition occurs at relatively early crank angle timing resulting in increased combustion noise
Solution Approach 1:
The combustion chamber is divided into a first region and a second region. The first region is where air-fuel mixture is formed for SI combustion, and the second region is where air-fuel mixture is formed for CI combustion. This spatial segmentation allows different combustion modes to occur in different zones, enabling the engine to achieve both efficient combustion and controlled autoignition timing.
Solution Approach 2:
Different quality air-fuel mixtures are created in different regions. The first region receives fuel injection timing and amount optimized for SI combustion, while the second region receives fuel injection timing and amount optimized for CI combustion. This local differentiation allows the system to maintain high combustion efficiency while controlling overall combustion noise by managing where and how autoignition occurs.
2Object-generated harmful factors
If cooled burned gas is introduced into the combustion chamber to decrease temperature and prevent premature autoignition, then combustion noise is reduced, but the temperature cannot be decreased to a predetermined temperature or lower, limiting the operation region
Solution Approach 1:
Instead of uniformly cooling the entire combustion chamber, the system segments the combustion chamber into two regions with different temperature characteristics. The first region maintains higher temperature for efficient SI combustion, while the second region allows controlled CI combustion. This segmentation enables the engine to operate across a wider range of conditions without requiring extreme temperature reduction throughout the chamber.
Solution Approach 2:
The system dynamically adjusts fuel injection timing and amount for each region based on operating conditions. By changing these parameters, the engine can adapt to different load and speed conditions, expanding the operation region where compression ignition can be effectively performed while maintaining control over combustion noise.
3Ease of operation
If the combustion speed in SI combustion is increased to improve controllability of CI combustion, then timing of autoignition can be accurately controlled, but the temperature in the combustion chamber before start of compression must be sufficiently high, reducing combustion stability
Solution Approach 1:
The division into first and second regions allows independent optimization of combustion parameters for each mode. The first region is optimized for stable SI combustion with appropriate fuel injection timing, while the second region is optimized for CI combustion controllability. This segmentation enables the system to achieve both goals simultaneously without compromise.
Solution Approach 2:
The controller monitors engine operating conditions and adjusts fuel injection timing and amount for both regions based on feedback signals. This closed-loop control ensures that SI combustion remains stable while maintaining accurate controllability of CI combustion timing, adapting to changing operating conditions in real-time.
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 expands the operation region for compression ignition, improves fuel economy, and reduces combustion noise by controlling the start of CI combustion and enhancing SI combustion controllability, while maintaining stability and reducing unburned fuel loss.
Implementation Method 1
air-fuel mixture in a combustion chamber is forcibly ignited to cause combustion by flame propagation
Implementation Method 2
locally decreasing the temperature in the region in which air-fuel mixture for CI combustion is formed, by the latent heat of vaporization of fuel injected into this region
Implementation Method 3
unburned air-fuel mixture in the combustion chamber is combusted by autoignition due to heat generation by the SI combustion
Data Source
AI summary
A control device for a compression autoignition engine includes an engine, a state quantity setting device, a spark plug, a controller, and a sensor. The spark plug receives a control signal from the controller and ignites air-fuel mixture at predetermined ignition timing such that the ignited air-fuel mixture is combusted by flame propagation and then unburned air-fuel mixture in a combustion chamber is combusted by autoignition. The controller outputs a control signal to an injector such that preceding injection and succeeding injection are performed in a compression stroke.