Engine Control Device Combustion Stability via Tumble Ratio Adjustment
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Solution Overview
Problem
Internal combustion engines with injectors and spark plugs in the upper combustion chamber face challenges in stabilizing air-fuel mixture concentration and combustion stability due to the influence of tumble flow and in-cylinder pressure, especially when trying to generate and maintain a ω tumble flow for exhaust gas purification catalyst activation.
Innovation Solution
A control device that includes an injector with injection holes oriented to pass the fuel spray under the spark plug's electrode, an in-cylinder pressure sensor, and a tumble flow control system to adjust the tumble ratio by controlling the flow velocity of the tumble flow, ensuring the second fuel injection overlaps with the spark period and ends before the spark, thereby stabilizing combustion by attracting the initial flame to the fuel spray.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the second fuel injection is performed in the middle stage to the latter stage of the expansion stroke to activate the exhaust gas purification catalyst, then the exhaust gas temperature can be increased, but the air-fuel mixture concentration becomes unstable due to the influence of tumble flow and in-cylinder pressure
Solution Approach 1:
The injector is positioned and oriented such that the fuel spray is injected toward the spark plug electrode in advance, so that when the spark fires, the flame directly contacts the fuel spray. This preliminary positioning of fuel ensures stable air-fuel mixture concentration at the combustion point while maintaining high exhaust gas temperature for catalyst activation.
Solution Approach 2:
The fuel injection is directed specifically toward the spark plug electrode region, creating a localized high-concentration fuel zone exactly where ignition occurs. This local concentration strategy ensures reliable combustion initiation while the overall air-fuel mixture remains suitable for catalyst activation and high exhaust temperature generation.
2Device complexity
If the injector is positioned in the upper part of the combustion chamber to enable direct injection, then the structure is simplified, but the air-fuel mixture concentration becomes unstable due to tumble flow influences
Solution Approach 1:
The upper combustion chamber injector is oriented to spray fuel toward the spark plug electrode in advance of ignition. This preliminary action ensures that fuel is already positioned at the ignition point when the spark fires, creating a stable local air-fuel mixture concentration despite the simplified upper-positioned structure and the presence of tumble flow.
3Stability of the object's composition
If the tumble ratio is increased to generate a strong tumble flow for combustion stability, then the combustion stability improves, but the injection timing and fuel spray characteristics become more difficult to control
Solution Approach 1:
The injector is oriented to create a localized fuel spray zone directly at the spark plug electrode, ensuring that fuel injection precision is critical only in the immediate vicinity of the ignition point. This local quality approach maintains combustion stability through strong tumble flow while reducing the overall injection timing precision requirements.
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 enhances combustion stability and reduces combustion fluctuations by optimizing the tumble ratio and injection timing, allowing for effective activation of the exhaust gas purification catalyst and improved engine performance.
Implementation Method 1
an ignition device arranged in a vicinity of a center of an upper part of a combustion chamber, and includes a spark plug for igniting an air-fuel mixture in a cylinder using a discharge spark
Implementation Method 2
an injector arranged nearer to an intake valve than the spark plug in the vicinity of the center of the upper part of the combustion chamber
Implementation Method 3
A tumble flow that flows so as to go toward a side of an exhaust valve from a side of an intake valve in the upper part of the combustion chamber is generated in the combustion chamber
Implementation Method 4
an exhaust gas purification catalyst configured to purify exhaust gas from the combustion chamber
Data Source
AI summary
A control device for an internal combustion engine is programmed, during a catalyst warm-up control, to perform first fuel injection by an injector in an intake stroke, control an ignition device so as to generate a discharge spark in a predetermined period in an expansion stroke, and perform second fuel injection, at a timing retarded from a compression top dead center, such that its injection period overlaps with at least a part of the predetermined period and an end timing of the injection period is advanced from an end timing of the predetermined period. Further, the control device is programmed, during the catalyst warm-up control, to control an actual tumble ratio depending on a result of determination using a first index value representing a speed of initial combustion accompanying an ignition by the ignition device and a second index value representing a speed of main combustion accompanying the ignition.