Compression Self-Ignition Engine Fuel Injection Control
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Solution Overview
Problem
Compression self-ignition engines face challenges in reducing combustion noise due to rapid increases in in-cylinder pressure caused by concurrent self-ignition of mixture gases, which existing technologies like split injection strategies do not fully address.
Innovation Solution
A control device for a compression self-ignition engine that adjusts fuel injection timings and amounts based on estimated in-cylinder temperature, with the first injection targeting radially outward parts to lower temperature and the second injection occurring when the mixture is harder to combust, preventing rapid pressure rises and noise increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If compression self-ignition combustion is performed, then thermal efficiency is improved, but combustion noise increases due to rapid increase in in-cylinder pressure
Solution Approach 1:
The fuel injection is divided into multiple separate injections during the compression stroke. The first fuel injection is performed at an earlier timing and the second fuel injection is performed at a later timing, so that fuel is not injected all at once. This segmentation prevents concurrent self-ignition of all fuel at once, thereby reducing the rapid increase in in-cylinder pressure and combustion noise while maintaining thermal efficiency.
Solution Approach 2:
The first fuel injection is performed in advance during the compression stroke before the mixture reaches the optimal combustion temperature. This preliminary fuel injection allows the fuel to mix with air and prepare for controlled combustion, preventing the rapid pressure rise that would occur if all fuel were injected at once near top dead center.
2Productivity
If fuel is injected into the cavity near compression top dead center, then combustion is stimulated, but rich mixture gas forms and causes rapid temperature increase and early combustion
Solution Approach 1:
Fuel injection is segmented into two distinct phases: first fuel injection at an earlier timing and second fuel injection at a later timing. This prevents the formation of a rich mixture gas in the cavity that would cause rapid temperature increase and early combustion, while still ensuring adequate combustion stimulation.
Solution Approach 2:
The fuel injection system dynamically adjusts the timing and amount of fuel injection based on the compression stroke position and mixture conditions. The control device determines appropriate first and second injection timings to optimize combustion while preventing premature or excessive temperature rise.
3Object-generated harmful factors
If split injection is used to disperse fuel, then combustion noise is reduced, but combustion may be too slow or timing may be off
Solution Approach 1:
The control device uses feedback from sensors (crankshaft position sensor, camshaft position sensor, intake air temperature sensor, etc.) to monitor engine conditions and dynamically adjusts the first and second fuel injection timings. This feedback mechanism ensures that combustion occurs at the optimal timing while maintaining reduced combustion noise through split injection.
Solution Approach 2:
The control device changes multiple parameters including first injection timing, second injection timing, first injection amount, and second injection amount based on engine operating conditions. This allows optimization of both combustion speed and noise reduction by adjusting the split injection parameters dynamically.
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 effectively reduces combustion noise and ensures proper compression self-ignition combustion by optimizing fuel distribution and ignition timing, preventing premature or late combustion and maintaining engine torque.
Implementation Method 1
the temperature at the radially-outward part of the combustion chamber, which is the part where the temperature becomes low easier than the center part of the combustion chamber, is further lowered by the latent heat of vaporization of the fuel in the first injection
Implementation Method 2
the mixture gas formed inside a combustion chamber (inside a cylinder) is compressed by a piston so that the mixture gas becomes high in temperature and pressure to combust by self-ignition
Data Source
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AI summary
A control device for a compression self-ignition engine includes a fuel injection system and an injection controller. While the engine is operated by CI combustion under a given first condition, a first injection is carried out in which fuel is injected at a first timing in a compression stroke and at which the fuel goes toward a part radially outward of a cavity formed in a crown surface of a piston, and a second injection is suspended. While the engine is operated by the CI combustion under a second condition in which a temperature inside a combustion chamber at a close timing of an intake valve becomes lower than the first condition, at least the second injection is carried out in which the fuel is injected at a second timing later than the first timing in the compression stroke and at which the fuel goes toward the cavity.