Two-Stage Piston Cavity Injection for Stable Multi-Stage Combustion
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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 is not maintained consistently when engine speed or load changes, affecting the realization of rapid multi-stage combustion.
Innovation Solution
The engine system includes a piston with a two-stage cavity, a fuel injection valve, a turbocharger, sensors, and a controller that adjusts fuel injection patterns and pressures to maintain a consistent distribution ratio between the upper and lower cavities by varying pilot and main injection amounts and timings based on engine state, ensuring fuel spray reaches the lip portion effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fuel injection valve injects fuel spray into the combustion chamber with a two-stage cavity, then the rapid multi-stage combustion can be realized, but the distribution ratio of fuel between the upper cavity and the lower cavity changes when engine speed or load changes, causing the rapid multi-stage combustion to fail
Solution Approach 1:
The fuel injection system dynamically adjusts injection parameters (injection pressure, injection timing, injection amount) based on real-time engine operating conditions (speed, load) to maintain consistent fuel distribution ratio between upper and lower cavities. The controller modifies injection control signals adaptively, ensuring the lip portion consistently directs fuel to the lower cavity regardless of operational state changes.
Solution Approach 2:
The system changes physical parameters of fuel injection (pressure, timing, duration) in response to engine speed and load variations. By adjusting these parameters, the injection system compensates for changes in combustion chamber environment and fuel spray properties, maintaining the desired fuel distribution ratio and ensuring rapid multi-stage combustion continues across all operating conditions.
2Power
If the engine operates at high speed and high load, then the boost pressure increases, but the fuel spray distribution to the upper and lower cavities becomes unbalanced, preventing rapid multi-stage combustion
Solution Approach 1:
The controller receives feedback signals from sensors monitoring engine speed, load, and combustion characteristics. Based on this feedback, the controller adjusts the fuel injection parameters in real-time to compensate for high boost pressure effects. This closed-loop control ensures that even under high power conditions, the fuel distribution ratio remains consistent and rapid multi-stage combustion is maintained.
Solution Approach 2:
The injection system dynamically responds to high-speed, high-load conditions by adjusting injection pressure and timing. The system adapts its behavior to overcome the challenges posed by high boost pressure, ensuring fuel spray still reaches the lip portion and distributes correctly to both cavities, thereby maintaining combustion pattern stability despite increased power output.
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 across varying engine conditions, improving thermal efficiency, reducing fuel consumption, and producing cleaner exhaust while maintaining quiet operation.
Implementation Method 1
a fuel injection valve that is disposed on a top surface of a combustion chamber formed by the cylinder and the piston, and injects fuel spray along an injection axis
Implementation Method 2
a turbocharger that is mounted on the engine and boosts intake air by exhaust energy of the engine
Implementation Method 3
rapid multi-stage combustion in which the change of the heat generation rate with respect to the progress of the crank angle forms a hill due to the heat generation of the pre-combustion and the heat generation of the main combustion being in smooth succession
Data Source
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 of the compression-ignition engine includes a lower cavity, an upper cavity, and a lip portion between the lower cavity and the upper cavity. A controller causes a main injection and at least one pilot injection to be executed when the engine 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 controller increases an injection amount per pilot injection when the engine operates in the second state than when the engine operates in the first state.