Compression-Ignition Engine Control via Partial Spark Ignition
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Solution Overview
Problem
Existing compression-ignition engines face challenges in achieving high combustion velocity and thermal efficiency due to fluctuations in combustion initiation timing and difficulty in controlling HCCI combustion during transient operations, particularly in maintaining optimal fuel reactivity for CI combustion.
Innovation Solution
A control apparatus for a compression-ignition engine that includes a swirl generation section, an injection control section, and an ignition control section, which generates a swirl flow and controls fuel injection and ignition timing to perform partial compression ignition combustion by sparking a portion of the air-fuel mixture and allowing the rest to undergo self-ignition, optimizing the timing of preceding and main ignitions based on swirl flow strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If HCCI combustion is used to achieve high thermal efficiency, then thermal efficiency is improved, but combustion initiation timing fluctuates significantly and control during transient operation becomes difficult
Solution Approach 1:
The combustion process is segmented into two distinct phases: SI combustion for a portion of the air-fuel mixture and CI combustion for the remaining mixture. This segmentation allows the system to leverage the stability of SI combustion for timing control while maintaining the high thermal efficiency of CI combustion, thereby resolving the contradiction between efficiency and timing stability.
Solution Approach 2:
Different combustion modes are applied to different regions of the air-fuel mixture within the combustion chamber. By creating local quality differences where some mixture undergoes SI combustion and other portions undergo CI combustion, the system achieves both stable timing control (from SI regions) and high thermal efficiency (from CI regions).
2Speed
If preceding ignition is carried out to increase combustion velocity, then combustion velocity is improved, but intermediate products are consumed by combustion preventing sufficient effect on CI combustion velocity
Solution Approach 1:
The preceding ignition is designed to provide only low ignition energy that locally generates fire without completely consuming the intermediate products. This partial action allows sufficient intermediate products to remain available for enhancing CI combustion velocity, while still achieving the desired effect of increased overall combustion velocity through the combined SI and CI processes.
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 enables high combustion velocity and superior thermal efficiency by modifying fuel properties through controlled spark ignitions, producing intermediate products that enhance CI combustion velocity while avoiding excessive noise and maintaining low NOx production.
Implementation Method 1
some of the air-fuel mixture is forcibly burned by flame propagation with the spark ignition as a start (SI combustion)
Implementation Method 2
gasoline fuel that is mixed with air is sufficiently compressed in a combustion chamber and is burned by self-ignition
Implementation Method 3
a swirl generation section that generates a swirl flow in the cylinder
Data Source
AI summary
The invention is provided with an ignition control section and an injection control section. When partial compression ignition combustion is carried out, the ignition control section causes an ignition plug to carry out: main ignition in which a spark is generated in a late period of a compression stroke or an initial period of an expansion stroke to initiate SI combustion; and preceding ignition in which the spark is generated at earlier timing than the main ignition. Also, when the partial compression ignition combustion is carried out, the injection control section causes an injector to inject fuel at such timing that the fuel exists in a cylinder at an earlier time point than the preceding ignition. Timing of the preceding ignition is more advanced when a swirl flow is gentle than when the swirl flow is strong.