Two-Stage Diesel Piston Cavity Injection Control for Stable Fuel Split
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Solution Overview
Problem
In compression-ignition engines with a two-stage cavity, the distribution ratio of fuel between the upper and lower cavities changes with engine speed and load, making it difficult to maintain rapid multi-stage combustion across varying operational states.
Innovation Solution
A controller adjusts the injection amounts of pilot and main injections to maintain a predetermined distribution ratio between the upper and lower cavities by increasing the pilot injection amount when the engine speed increases and reducing it when the speed decreases, ensuring consistent fuel distribution across different engine states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the engine speed and load change, then the total fuel amount injected and injection pressure change, but the distribution ratio of fuel between upper cavity and lower cavity changes, making rapid multi-stage combustion difficult to maintain
Solution Approach 1:
The patent applies dynamics by making the injection system adjustable based on operating conditions. The fuel injection control unit dynamically changes injection parameters (timing, amount, pressure) according to engine speed and load, allowing the system to adapt to varying operational states while maintaining stable fuel distribution between cavities through coordinated control of multiple injection events
Solution Approach 2:
The patent utilizes parameter changes by modifying injection pressure, injection timing, and fuel amount as operating conditions change. By adjusting these parameters during pilot injection and main injection events, the system compensates for variations in engine speed and load, ensuring the fuel distribution ratio between upper and lower cavities remains stable across different operational states
2Speed
If the fuel spray penetration increases at high engine speed, then the fuel reaches the lip portion later, but the distribution ratio to lower cavity increases excessively
Solution Approach 1:
The patent applies segmentation by dividing the fuel injection into multiple distinct events: pilot injection (first and second injections) and main injection. This segmentation allows independent control of fuel delivery to different cavities. The pilot injections are specifically designed to target the upper cavity through the lip portion, while the main injection supplies the lower cavity, thereby maintaining precise fuel distribution ratios even at high engine speeds where spray penetration characteristics change
Solution Approach 2:
The patent implements preliminary action by performing pilot injections before the main injection event. These preliminary pilot injections deliver a controlled amount of fuel to the upper cavity, establishing the correct distribution ratio in advance. This preliminary fuel delivery compensates for the delayed arrival of fuel spray at the lip portion caused by increased penetration at high engine speeds, ensuring proper fuel distribution is achieved before the main combustion event
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 allows for consistent rapid multi-stage combustion, improving thermal efficiency, reducing fuel consumption, and enhancing exhaust gas cleaning, even under changing engine conditions.
Implementation Method 1
a fuel injection valve 18 for injecting fuel spray into the combustion chamber 6
Implementation Method 2
The rapid multi-stage combustion can be realized by performing at least one pilot injection and a main injection
Implementation Method 3
compression-ignition engine
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
In a compression-ignition engine having a two-stage cavity, the distribution ratio between fuel for an upper cavity and fuel for a lower cavity is maintained even when the operational state of the engine changes. A piston 5 of the compression-ignition engine includes a lower cavity (lower cavity portion 51), an upper cavity (upper cavity portion 52), and a lip portion 53 between the lower cavity and the upper cavity. A control unit (ECU 10) causes a main injection and at least one pilot injection to be executed when an engine 1 operates in a first state and a second state in which the speed is higher than the speed in the first state. The fuel spray is distributed to the lower cavity and the upper cavity. The control unit maintains an injection amount of the main injection and increases an injection amount of the pilot injection when the engine operates in the second state as compared to when the engine operates in the first state.