Engine Control System for Stable Partial Compression-Ignition Combustion
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Solution Overview
Problem
Partial compression-ignition combustion engines face challenges in maintaining combustion stability due to varying engine speeds, particularly because the flame core growth is hindered at high speeds, leading to unstable combustion timing and efficiency.
Innovation Solution
A control system that adjusts fuel injection patterns by performing pre-injections and post-injections during the intake and compression strokes, increasing the ratio of post-injection fuel as engine speed rises, and utilizing a swirl mechanism to enhance fuel concentration at the ignition timing, ensuring stable flame core formation and growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine operates at high speed, then the power output increases, but the flame core growth becomes insufficient and combustion stability deteriorates
Solution Approach 1:
The system performs a first fuel injection during the intake stroke to prepare fuel-air mixture in advance, and a second fuel injection during the compression stroke to ensure proper fuel concentration at ignition timing. This preliminary preparation of fuel distribution allows the flame core to grow properly even at high engine speeds where combustion time is limited.
Solution Approach 2:
The control system dynamically adjusts the fuel injection parameters including injection timing, injection amount, and injection pressure based on engine speed. At high speeds, the system modifies these parameters to ensure sufficient fuel concentration in the combustion chamber, compensating for the reduced time available for flame core growth and maintaining combustion stability.
2Reliability
If the ratio of post-injection fuel amount is increased to maintain fuel concentration at high speeds, then combustion stability improves, but the complexity of fuel injection control increases
Solution Approach 1:
The fuel injection system employs dynamic control where the injection parameters (timing, duration, amount) are continuously adjusted based on real-time engine operating conditions including speed and load. The control unit modifies the injection strategy adaptively, increasing post-injection ratio at high speeds while maintaining simpler control at lower speeds, thus balancing stability with control complexity.
Solution Approach 2:
The fuel injection process is divided into distinct segments: a first injection during the intake stroke and a second injection during the compression stroke. Each segment serves a specific purpose - the first establishes baseline fuel distribution while the second adjusts fuel concentration for optimal combustion. This segmentation allows independent optimization of each injection phase without requiring complex integrated control.
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 ensures stable partial compression-ignition combustion across varying engine speeds by maintaining high fuel concentration and promoting consistent flame core growth, thereby stabilizing combustion timing and improving thermal efficiency.
Implementation Method 1
a swirl mechanism configured to generate the swirl flow
Implementation Method 2
combust a portion of the mixture gas by spark ignition using a spark plug
Implementation Method 3
combusting a portion of the mixture gas through flame propagation caused by spark ignition
Implementation Method 4
the remaining mixture gas is combusted by self-ignition (CI (compression ignition) combustion)
Data Source
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AI summary
A control system for a compression-ignition engine is provided, which includes an engine having a combustion chamber, an injector configured to supply fuel into the combustion chamber, a spark plug, a swirl valve provided to an intake passage of the engine, and a controller. The controller includes a processor configured to execute a swirl adjusting module to adjust a swirl valve opening to generate a swirl flow inside the combustion chamber, a fuel injection amount controlling module to control fuel injection amounts of pre-injection and post-injection so as to increase a ratio of an injection amount of the post-injection to a total fuel injection amount into the combustion chamber in one cycle as an engine speed increases, and a combustion controlling module to control the spark plug to ignite at a given ignition timing after the swirl generation and fuel injection, so that partial compression-ignition combustion is performed.