Spark-Ignition Engine 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 with a fuel injection system that injects fuel at a timing near the compression top dead center with high fuel pressure, shortening the injection, air-fuel mixture forming, and combustion periods, and retarding the ignition timing to avoid abnormal combustion.
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 is easily caused
Solution Approach 1:
The patent applies parameter changes by injecting fuel at high pressure (increasing fuel pressure parameter) and at a specific timing near compression top dead center (changing injection timing parameter). These parameter changes shorten the reactable time of unburned air-fuel mixture, preventing abnormal combustion while maintaining high compression ratio for thermal efficiency improvement.
2Device complexity
If fuel is injected during intake stroke with conventional timing, then fuel injection is simple, but reactable time of unburned air-fuel mixture is prolonged causing abnormal combustion
Solution Approach 1:
The patent changes the injection timing parameter to near compression top dead center and increases fuel pressure parameter. These parameter changes reduce the reactable time of unburned air-fuel mixture without complicating the fuel injection system structure, thereby preventing abnormal combustion.
3Reliability
If ignition timing is retarded to avoid abnormal combustion, then abnormal combustion is reduced, but thermal efficiency and torque are degraded
Solution Approach 1:
The patent applies preliminary action by injecting fuel near compression top dead center before ignition. This preliminary fuel injection and compression reduces the reactable time of unburned mixture in advance, allowing ignition timing to be advanced for high thermal efficiency without causing abnormal combustion.
4Duration of action of moving object
If fuel injection pressure is increased to shorten injection period, then injection period is shortened, but fuel injection system complexity increases
Solution Approach 1:
The patent changes the fuel pressure parameter to high pressure level. This parameter change shortens the injection period duration without requiring complex injection system structure, as it utilizes the existing injection system operating at elevated pressure.
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 pre-ignition and knocking, while allowing for advanced ignition timing to improve thermal efficiency and torque, and reduces the need for retarding the ignition timing, thus enhancing fuel consumption and emission performance.
Implementation Method 1
a fuel injection valve for injecting the fuel into the cylinder
Implementation Method 2
an ignition plug arranged to be oriented inside the cylinder and for igniting air-fuel mixture within the cylinder
Implementation Method 3
a fuel pressure variable mechanism for changing a pressure of the fuel that is injected by the fuel injection valve
Implementation Method 4
a cylinder of which a geometric compression ratio is set to 14:1 or above
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 controls 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 valve to perform a fuel injection at least at a timing that is more retarded than an injection timing of a fuel within the low engine load range and is within 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 within the retard period and further after the fuel injection.