Partial Compression Ignition Control for Combustion Velocity
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Solution Overview
Problem
Existing compression-ignition engines face challenges in achieving high combustion velocity and thermal efficiency due to variations 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 incorporates a system for partial compression ignition combustion, utilizing an ignition plug to perform both preceding and main ignitions, with the energy of the preceding ignition adjusted based on in-cylinder pressure to enhance fuel reactivity and promote SI and CI combustion modes, thereby optimizing combustion velocity and thermal efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If HCCI combustion is used to increase combustion velocity and thermal efficiency, then combustion velocity and thermal efficiency are improved, but combustion initiation timing varies significantly due to external factors and control becomes difficult during transient operation
Solution Approach 1:
The patent segments the combustion process into two distinct modes: SI combustion for the first portion of fuel and CI combustion for the second portion. This segmentation allows independent control of each combustion mode, ensuring stable combustion initiation timing while achieving high combustion velocity through the CI portion, thereby resolving the contradiction between combustion velocity and timing stability.
Solution Approach 2:
The patent changes the combustion mode parameter from uniform HCCI to a variable mix of SI and CI combustion based on fuel injection timing and amount. By adjusting these parameters, the system maintains stable combustion initiation while achieving high combustion velocity, resolving the contradiction between speed and reliability.
2Speed
If preceding ignition is performed to increase fuel reactivity and combustion velocity, then combustion velocity and thermal efficiency are improved, but a significant amount of intermediate product is consumed by combustion, preventing sufficient effect
Solution Approach 1:
The patent applies partial action by performing preceding ignition only on a portion of the fuel (first fuel injection) rather than all fuel. This partial preceding ignition increases fuel reactivity and combustion velocity for the CI combustion portion while avoiding excessive consumption of intermediate products, thus resolving the contradiction between combustion velocity improvement and energy loss.
3Loss of energy
If the entire air-fuel mixture is burned by self-ignition to achieve HCCI combustion, then thermal efficiency is improved, but combustion initiation timing varies due to external factors
Solution Approach 1:
The patent segments the fuel combustion into two parts: first fuel injected and burned by SI combustion with controlled ignition timing, and second fuel injected and burned by CI combustion. This segmentation ensures stable combustion initiation timing for the SI portion while maintaining high thermal efficiency through the CI portion, resolving the contradiction between thermal efficiency and timing stability.
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
The system achieves high combustion velocity and superior thermal efficiency by modifying fuel properties through controlled preceding ignitions, ensuring efficient fuel consumption and torque performance while minimizing combustion noise and NOx production.
Implementation Method 1
an ignition plug that ignites air-fuel mixture
Implementation Method 2
the rest of the air-fuel mixture is burned by the self-ignition (CI combustion)
Implementation Method 3
some of the air-fuel mixture is forcibly burned by flame propagation with the spark ignition as a start (SI combustion)
Data Source
AI summary
An engine control apparatus includes an ignition control section and an injection control section. When the 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 a expansion stroke to initiate the 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 the injector to inject fuel at such timing that the fuel exists in a cylinder at an earlier time point than the preceding ignition. The energy of the preceding ignition is set to be higher when the in-cylinder pressure specified by the in-cylinder pressure specification section is high than when the in-cylinder pressure is low.