Pre-Chamber Engine Combustion Control for High-Load Knock Suppression
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Solution Overview
Problem
Conventional engine systems with auxiliary chambers experience abnormal combustion due to high engine loads, leading to high-frequency oscillations and noise, as the diameter of the communicating hole cannot be varied to control flame blow-off effectively.
Innovation Solution
An engine system with a control device that adjusts the air-fuel ratio and fuel injection timing in the auxiliary chamber based on engine load, making the mixture gas leaner during high loads to slow down flame propagation and reduce momentum, thereby controlling abnormal combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the mixture gas inside the auxiliary chamber is ignited in the rich state to accelerate combustion propagation, then the combustion efficiency is improved, but the flame blows off powerfully from the communicating holes causing abnormal combustion and high-frequency oscillation
Solution Approach 1:
The invention changes the air-fuel ratio parameter of the mixture gas inside the auxiliary chamber from rich to lean state. By controlling the injector to make the mixture gas leaner, the flame propagation speed is reduced, which prevents the flame from blowing off powerfully through the communicating holes, thereby suppressing abnormal combustion and high-frequency oscillation while maintaining combustion efficiency
Solution Approach 2:
The invention dynamically adjusts the air-fuel ratio based on engine load conditions. The control device determines engine load and controls the injector to adjust fuel injection amount, making the mixture gas leaner under high load conditions to prevent abnormal combustion, while allowing richer mixture under low load conditions to maintain combustion efficiency
2Productivity
If the diameter of the communicating hole is increased to improve flame blow-off control, then the combustion propagation is enhanced, but the flame momentum becomes too strong causing pipe resonance and vibration
Solution Approach 1:
Instead of changing the physical dimension (diameter) of the communicating hole, the invention changes the chemical composition parameter (air-fuel ratio) of the mixture gas. By making the mixture gas leaner, the flame propagation characteristics are modified, reducing flame momentum without requiring changes to the communicating hole diameter, thus avoiding pipe resonance and vibration
3Reliability
If the fuel injection amount is increased to maintain combustion stability, then the combustion reliability is improved, but the mixture gas becomes too rich causing excessive flame propagation speed and abnormal combustion
Solution Approach 1:
The invention optimizes the air-fuel ratio parameter to achieve a lean mixture state that balances combustion stability and flame propagation speed. By precisely controlling the fuel injection amount to create a lean mixture, the system maintains reliable combustion while limiting flame propagation speed to prevent abnormal combustion
Solution Approach 2:
The control device uses feedback from engine load determination to dynamically adjust the fuel injection amount. Based on the determined engine load, the control device controls the injector to achieve the appropriate air-fuel ratio, ensuring combustion stability while preventing excessive flame propagation speed
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
The system effectively suppresses abnormal combustion by making the mixture gas in the auxiliary chamber leaner during high engine loads, reducing flame propagation and momentum, thus preventing high-frequency oscillations and noise.
Implementation Method 1
an ignition plug configured to ignite the mixture gas inside the auxiliary chamber
Implementation Method 2
an injector configured to spray fuel to the auxiliary chamber
Data Source
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AI summary
An engine system includes an engine, a main combustion chamber formed by a cylinder head and a piston, an auxiliary chamber formed with a communicating hole communicating with the main combustion chamber, an injector configured to inject fuel into the main combustion chamber, an ignition plug provided to the auxiliary chamber and configured to ignite a mixture gas inside the auxiliary chamber, an accelerator opening sensor, and a control device. The control device controls the injector so that an air-fuel ratio of the mixture gas inside the auxiliary chamber becomes a first air-fuel ratio when an engine load range is a first range, and the air-fuel ratio of the mixture gas inside the auxiliary chamber becomes a second air-fuel ratio leaner than the first air-fuel ratio when the engine load range is a second range where the engine load is higher than in the first range.