Spark-Ignition Engine Fuel Injection Control for Abnormal Combustion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Spark-ignition gasoline engines with high geometric compression ratios experience abnormal combustion issues such as pre-ignition and knocking, particularly at low engine speeds and high engine loads, due to prolonged unburned air-fuel mixture reactable times.
Innovation Solution
A control device for spark-ignition gasoline engines that includes a fuel injection mechanism with a cylinder internal injection valve and a fuel pressure variable mechanism, where fuel is injected near the compression top dead center with high pressure during the retard period from the late compression stroke to early expansion stroke, shortening the injection, air-fuel mixture forming, and combustion periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the geometric compression ratio is increased to improve thermal efficiency, then thermal efficiency is improved, but abnormal combustion such as pre-ignition and knocking occurs more easily
Solution Approach 1:
The fuel injection is performed preliminarily during the compression stroke before combustion occurs. By injecting fuel early in the compression stroke, the air-fuel mixture has sufficient time to form and mix before ignition, which prevents abnormal combustion while maintaining the benefits of high compression ratio for thermal efficiency
Solution Approach 2:
The injection timing is made dynamic and adjustable based on engine operating conditions. The control device adjusts the injection timing within the compression stroke according to engine speed and load, optimizing the balance between preventing abnormal combustion and maintaining thermal efficiency across different operating ranges
2Reliability
If fuel injection timing is retarded to avoid abnormal combustion, then abnormal combustion is reduced, but thermal efficiency and torque decrease
Solution Approach 1:
Instead of retarding injection timing, the invention performs preliminary injection during the compression stroke. This preliminary action ensures complete air-fuel mixing before combustion, allowing advanced ignition timing to be used for maintaining thermal efficiency while the high compression ratio prevents abnormal combustion
Solution Approach 2:
The invention changes the parameter of injection timing from post-compression or expansion stroke to during compression stroke. This parameter change fundamentally alters the combustion characteristics, allowing both advanced ignition timing and high compression ratio to coexist without causing abnormal combustion
3Quantity of substance
If unburned air-fuel mixture reactable time is prolonged, then combustion completeness is improved, but abnormal combustion such as knocking increases
Solution Approach 1:
The fuel is injected preliminarily during the compression stroke, allowing the air-fuel mixture to form and mix thoroughly before combustion. This preliminary mixing ensures combustion completeness while the controlled timing prevents excessive reactable time that would lead to knocking
Solution Approach 2:
The injection during compression stroke creates a continuous and controlled air-fuel mixing process throughout the compression phase. This continuous mixing ensures complete combustion while maintaining controlled reaction timing, preventing the uncontrolled prolonged reactable time that causes knocking
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 effectively reduces the reactable time of the unburned air-fuel mixture, preventing abnormal combustion, allowing for advanced ignition timing, improved thermal efficiency, and increased torque while avoiding the need for ignition timing retardation.
Implementation Method 1
a fuel pressure variable mechanism for changing a pressure of the fuel that is injected by the cylinder internal injection valve
Implementation Method 2
injecting the fuel into a cylinder at a timing near a compression top dead center with a comparatively high fuel pressure
Implementation Method 3
a combustion period from when the combustion starts by the combustible air-fuel mixture being ignited around the ignition plug to when the combustion ends
Data Source
AI summary
The disclosure provides a control device of a spark-ignition gasoline engine. When an operating state of an engine body is within a low engine speed range, a controller operates a fuel pressure variable mechanism so that a fuel pressure is higher within a high engine load range compared to a low engine load range, the controller operates, within the high engine load range, a fuel injection mechanism to perform at least a fuel injection into the cylinder by a cylinder internal injection valve at a timing during a retard period from a late stage of a compression stroke to an early stage of an expansion stroke, and the controller operates, within the high engine load range, an ignition plug to ignite at a timing during the retard period and after the fuel injection.