Pre-Chamber Engine Sub-Chamber Volume Ratio for Knock Control
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Solution Overview
Problem
Strong knock, a form of abnormal combustion causing noise and potential engine damage, occurs in spark ignition engines, particularly in the operating region of high load and high rotation, and is exacerbated by pre-chamber ignition systems due to excessive flame momentum.
Innovation Solution
The engine is configured with a specific ratio of sub-chamber to stroke volume between 0.00005 and 0.00045, and a bore/stroke ratio of 1 to 1.5, along with a compression ratio of 14 to 25, to control the momentum of the flame and prevent strong knock, using a passive pre-chamber ignition system with four to six through-holes in the partition wall for optimal flame distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a pre-chamber ignition system is used to improve thermal efficiency and ensure combustion, then flame propagation speed increases, but strong knock occurs in high load and high rotation operating regions due to excessive flame momentum
Solution Approach 1:
The patent applies parameter changes by precisely controlling the sub-chamber volume ratio (0.00005-0.00045) and bore/stroke ratio (1.0-1.5) to optimize flame momentum. This resolves the contradiction by adjusting geometric parameters to achieve sufficient flame propagation for efficient combustion while preventing excessive momentum that causes strong knock in high load/high rotation conditions
2Reliability
If the sub-chamber volume is increased to enhance flame injection, then combustion stability improves, but the ratio exceeds the optimal range causing excessive flame momentum and strong knock
Solution Approach 1:
The patent uses parameter changes by defining a precise sub-chamber volume ratio range (0.00005-0.00045) that balances combustion stability with knock prevention. This optimal parameter range ensures reliable flame injection while controlling flame momentum to avoid strong knock
Solution Approach 2:
The patent applies partial action by using a relatively small sub-chamber volume ratio within the optimal range, sufficient for stable combustion but not excessive enough to generate harmful flame momentum. This partial optimization resolves the contradiction between reliability and harmful effects
3Power
If the bore/stroke ratio is increased to improve power output, then engine performance increases, but flame distribution becomes less optimal and knock resistance decreases
Solution Approach 1:
The patent applies parameter changes by optimizing the bore/stroke ratio within the range of 1.0-1.5, which balances power output with optimal flame distribution. This parameter optimization ensures high engine performance while maintaining adequate knock resistance through improved flame propagation characteristics
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 suppresses strong knock, improving thermal efficiency and maintaining stable combustion with good fuel efficiency in both medium load and high load, high rotation operating regions.
Implementation Method 1
ignites an air-fuel mixture in the sub-chamber to inject flame to the main chamber through the openings of the partition wall, and burns the air-fuel mixture in the main chamber
Data Source
AI summary
To effectively suppress strong knock that occurs in the operating region of high load and high rotation in a specific engine having a pre-chamber in a combustion chamber, the engine includes a piston that defines a combustion chamber together with a cylinder block and a cylinder head. The combustion chamber includes a sub-chamber and a main chamber separated from the sub-chamber by a pre-chamber. The specific ratio obtained by dividing a volume of the sub-chamber by a stroke volume of a cylinder is greater than or equal to 0.00005 and less than or equal to 0.00045.