Two-Stage Diesel Piston Injection Control for Stable Fuel Distribution
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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, disrupting rapid multi-stage combustion, which is essential for efficient fuel consumption and exhaust cleaning.
Innovation Solution
A controller adjusts the fuel injection pattern by varying the number and timing of pilot and main injections to maintain a consistent distribution ratio between the upper and lower cavities across different engine states, ensuring the fuel spray penetrates effectively regardless of speed or load changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the fuel spray is injected into the combustion chamber with a fixed injection pattern, then the injection system is simple to control, but the distribution ratio of fuel between the upper cavity and lower cavity changes with engine speed and load, disrupting rapid multi-stage combustion
Solution Approach 1:
The injection control system dynamically adjusts the number and timing of pilot injections and main injections based on engine operating conditions (speed and load). The controller varies the injection pattern adaptively to maintain consistent fuel distribution ratio between upper and lower cavities across different operational states, transforming a static injection system into a dynamic one that responds to changing conditions.
Solution Approach 2:
The system changes injection parameters (number of pilot injections, timing of pilot injections, timing of main injection, fuel injection amounts) to maintain optimal fuel distribution. By adjusting these parameters based on engine speed and load, the system compensates for changes in combustion chamber pressure and fuel spray properties, ensuring consistent rapid multi-stage combustion performance.
2Manufacturing precision
If the number of pilot injections is increased to maintain fuel distribution, then the fuel distribution ratio can be maintained, but the injection timing precision requirements increase
Solution Approach 1:
The fuel injection is divided into multiple pilot injections and a main injection, with each injection targeting specific cavities (upper or lower) in sequence. This segmentation allows precise control over fuel distribution to different cavities by adjusting the number and timing of each injection event, achieving accurate fuel distribution through staged delivery rather than a single bulk injection.
Solution Approach 2:
Pilot injections are performed before the main injection to prepare the fuel distribution pattern. By injecting fuel in advance into specific cavities (upper or lower) through controlled pilot injections, the system establishes the desired fuel distribution ratio before the main combustion event, ensuring optimal conditions for rapid multi-stage combustion.
3Speed
If the injection pressure is increased to improve fuel spray penetration, then the fuel spray penetration improves, but the fuel spray scattering increases, altering the distribution ratio
Solution Approach 1:
The system uses periodic pulse injections (pilot injections followed by main injection) rather than continuous injection. Each pulse is precisely timed and controlled to deliver fuel to specific cavities at optimal moments during the combustion cycle. This periodic action allows the fuel spray to penetrate effectively while maintaining control over distribution by resetting the injection pattern for each combustion event based on current 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
This configuration allows for consistent rapid multi-stage combustion, improving thermal efficiency, reducing fuel consumption, and maintaining exhaust cleanliness across varying engine conditions.
Implementation Method 1
a fuel injection valve (18) that injects fuel spray into the combustion chamber (6)
Implementation Method 2
the fuel spray injected from the fuel injection valve is distributed to the upper cavity and the lower cavity at a predetermined ratio by a lip portion between the upper cavity and the lower cavity
Implementation Method 3
The rapid multi-stage combustion can be realized by performing at least one pilot injection and a main injection
Implementation Method 4
The rapid multi-stage combustion can improve thermal efficiency and improve emission performance while suppressing the increasement of combustion noise
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 the 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 increases an injection amount per pilot injection when the engine operates in the second state than when the engine operates in the first state.