Pre-Chamber Engine Combustion Control
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Solution Overview
Problem
Passive type pre-chamber ignition systems face challenges in simultaneously improving thermal efficiency in medium load engine operations and suppressing knocking in high load and high rotation operations due to the unique determination of pre-chamber volume and injection hole diameter, which affects the jet potential and energy transfer ratio.
Innovation Solution
The engine design includes a main combustion chamber, a pre-chamber with multiple injection holes, and a spark plug, with a compression ratio between 14 and 24 and a volume index V·ε between 1.03 cm3 and 5.92 cm3, allowing for controlled jet potential to balance thermal efficiency and knocking suppression by adjusting the pre-chamber volume and compression ratio to maintain the jet potential within a local minimum range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pre-chamber volume and injection hole specifications are determined to increase jet potential for improving thermal efficiency in medium load operation, then thermal efficiency is improved, but knocking occurs easily in high load operation
Solution Approach 1:
The patent applies parameter changes by establishing a specific range for the product of pre-chamber volume (V) and compression ratio (ε), namely 1.03 cm³ ≤ V·ε ≤ 5.92 cm³. This parameter constraint allows the system to achieve optimal jet potential for thermal efficiency while preventing excessive knocking in high load operations through quantitative control of the pre-chamber characteristics.
2Productivity
If the compression ratio is increased to improve filling degree of air-fuel mixture in pre-chamber, then thermal efficiency is improved, but knocking is easily caused in high load operation
Solution Approach 1:
The patent establishes a specific range for the compression ratio (14 ≤ ε ≤ 24) and combines it with the pre-chamber volume constraint (1.03 cm³ ≤ V·ε ≤ 5.92 cm³). This parameter optimization ensures sufficient filling degree of air-fuel mixture in the pre-chamber for effective ignition while preventing excessive knocking in high load operations through balanced control of compression ratio and pre-chamber volume.
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 effectively improves thermal efficiency in medium load operations while suppressing knocking in high load and high rotation operations by maintaining the jet potential within a specific range, ensuring efficient energy transfer and preventing excessive knocking.
Implementation Method 1
a spark plug that ignites an air-fuel mixture in the pre-chamber
Implementation Method 2
guides the air-fuel mixture formed in the main combustion chamber in the compression stroke to the vicinity of the spark plug through the injection holes
Implementation Method 3
an air-fuel mixture is ignited in the pre-chamber so that a flame is ejected as a jet blast through the injection holes of the pre-chamber into the main combustion chamber
Data Source
AI summary
To meet both a request to improve the thermal efficiency in the medium load operation of an engine and a request to suppress knocking in the high load and high rotation operation of the engine, the engine includes a main combustion chamber including a cylinder block, a cylinder head, and a piston; a pre-chamber having a plurality of injection holes that are open into the main combustion chamber; and a spark plug that ignites an air-fuel mixture in the pre-chamber. A compression ratio of the main combustion chamber is not less than 14 and not more than 24. A second index that is a product between a volume of the pre-chamber and the compression ratio is not less than 1.03 cm3 and not more than 5.92 cm3.