Engine Control Device for Stable SPCCI Combustion
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Solution Overview
Problem
Existing engine control devices struggle to maintain stable combustion and control mixture gas distribution, particularly in low temperature environments, leading to unstable SI combustion and compromised CI combustion, resulting in increased NOx generation and reduced fuel efficiency.
Innovation Solution
A control device that utilizes a swirl control valve, fuel injector, and spark plug, controlled by a processor to manage fuel injection timing and swirl flow, creating a stratified mixture gas distribution suitable for both SI and CI combustion, ensuring stable ignition and efficient combustion even at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the engine operates in a low temperature environment, then the temperature inside the combustion chamber drops, but this makes spark ignition difficult and degrades SI combustion stability
Solution Approach 1:
The fuel injection is segmented into multiple stages: a first fuel injection at a first timing (intake stroke to intermediate compression stroke) and a second fuel injection at a second timing (retarded timing). This segmentation creates different mixture distributions - a lean background mixture from the first injection and a rich localized mixture from the second injection - enabling reliable ignition and stable combustion even at low temperatures
Solution Approach 2:
The patent creates local quality differences in the combustion chamber by forming a stratified mixture distribution where a rich mixture gas is concentrated around the spark plug location (through the second fuel injection) while the rest of the chamber has a leaner mixture (from the first injection). This local enrichment ensures reliable spark ignition in the rich zone while the overall lean mixture maintains combustion stability
2Speed
If the flame propagation slows down due to low temperature, then the distribution of rich and lean mixture gas becomes unsuitable, but this also prevents achieving NOx reduction and fuel efficiency improvement
Solution Approach 1:
The first fuel injection is performed in advance (during intake stroke to intermediate compression stroke) to pre-establish a lean background mixture distribution throughout the combustion chamber. This preliminary action ensures that even if flame propagation is slow due to low temperature, there is already a suitable lean mixture distribution in place that promotes stable combustion and reduces NOx generation
3Stability of the object's composition
If sections with different fuel concentrations scatter around at ignition timing, then an uneven mixture gas distribution is formed, but this increases combustion noise and generates NOx
Solution Approach 1:
The control device uses feedback from engine operating conditions (temperature, load, speed) to dynamically adjust the fuel injection timings and amounts for both the first and second injections. This feedback control optimizes the mixture distribution to maintain uniformity at ignition timing, preventing excessive combustion noise and NOx generation while adapting to varying operating conditions
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 solution achieves stable SPCCI combustion with reduced NOx generation and improved fuel efficiency by forming a rich mixture gas distribution near the spark plug and a lean distribution in the combustion chamber, enhancing ignition stability and combustion performance across varying engine load ranges.
Implementation Method 1
an auxiliary injection in which a small amount of fuel is injected is performed in a final stage of compression stroke. By causing the fuel to swirl and diffuse in the swirl flow, the stratified mixture gas is formed around a spark plug
Implementation Method 2
an auxiliary injection in which a small amount of fuel is injected is performed in a final stage of compression stroke
Implementation Method 3
a spark plug disposed to be oriented into the combustion chamber and configured to perform a forced ignition
Implementation Method 4
CI combustion of an unburned mixture gas occurs by self-ignition
Data Source
AI summary
A control device for an engine is provided, which includes a fuel injector attached to the engine, a spark plug disposed to be oriented into a combustion chamber, a swirl control valve provided in an intake passage, and a controller connected to the fuel injector, the spark plug, and the swirl control valve and configured to control the fuel injector, the spark plug, and the swirl control valve. The swirl control valve closes in a given operating state of the engine. The fuel injector injects fuel after the swirl control valve is closed, between intake stroke and an intermediate stage of compression stroke. The fuel injector injects the fuel after the first fuel injection. The spark plug performs the ignition after the second fuel injection so that the mixture gas starts combustion by flame propagation and then unburned mixture gas self-ignites.