Spark-Ignition Combustion Chamber Segmentation for Anti-Knocking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional combustion chamber structures for spark-ignition engines face challenges in achieving higher compression ratios without inducing abnormal combustion, such as knocking, which limits the increase in compression ratio and thus fuel efficiency.
Innovation Solution
A combustion chamber structure with a pent-roof design featuring a first and second combustion space separated by a small interspace zone, where combustion occurs at a low speed in the initial primary combustion period and high speed in the final primary combustion period, effectively suppressing knocking by controlling in-cylinder pressure and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a higher compression ratio is achieved by reducing combustion chamber volume, then fuel economy is improved, but abnormal combustion (knocking) occurs more frequently
Solution Approach 1:
The combustion chamber is divided into a first combustion space around the spark plug and a second combustion space around the cylinder bore circumference, separated by a small interspace zone. This segmentation allows different combustion phases to occur in different regions, enabling high compression ratio while controlling combustion speed to prevent knocking.
Solution Approach 2:
Different regions of the combustion chamber are given different functional characteristics. The first combustion space near the spark plug is designed for initial combustion, while the second combustion space at the periphery is designed for final-stage combustion. The small interspace zone between them provides localized flow control to regulate combustion propagation speed.
2Duration of action of moving object
If a pent-roof type combustion chamber structure is used to reduce combustion chamber volume, then compression ratio increases, but combustion speed control becomes difficult
Solution Approach 1:
The pent-roof combustion chamber is segmented into distinct combustion spaces with a small interspace zone, allowing different combustion speeds in different regions. This enables the maintenance of high compression ratio geometry while controlling overall combustion speed through the interspace zone.
Solution Approach 2:
The combustion chamber geometry parameters are optimized by creating a small interspace zone with specific dimensions between the ceiling wall and piston top surface. This parameter change controls the combustion propagation speed through the interspace zone, allowing speed regulation despite the compact pent-roof structure.
3Productivity
If combustion chamber volume is reduced to increase compression ratio, then fuel efficiency improves, but in-cylinder pressure and temperature control becomes challenging
Solution Approach 1:
The combustion chamber is segmented into multiple spaces that sequentially combust the air-fuel mixture. This segmentation extends the combustion duration and distributes the pressure and temperature rise over time, preventing excessive peak values even with reduced overall combustion chamber volume.
Solution Approach 2:
The small interspace zone is pre-configured between the ceiling wall and piston top surface to create a controlled flow path. This preliminary structural arrangement ensures that combustion propagation is regulated as it passes through the interspace zone, controlling pressure and temperature development before the main combustion event.
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 design allows for a higher compression ratio with enhanced anti-knocking performance and improved fuel economy by optimizing combustion speed and pressure management.
Implementation Method 1
a spark plug having a sparking end protruding from the ceiling wall into the combustion chamber
Implementation Method 2
combustion occurs at a low speed in the initial primary combustion period and high speed in the final primary combustion period
Data Source
AI summary
This invention relates to a combustion chamber structure for a spark-ignition engine, which comprises a combustion chamber defined between a bottom surface of a cylinder head and a top surface of a piston in such a manner that the bottom surface of the cylinder head serves as a ceiling wall thereof, and a spark plug having a sparking end protruding from the ceiling wall into the combustion chamber. In this combustion chamber structure, when the piston is at a top dead center, a principal space of the combustion chamber is comprised of a first combustion space around the sparking end of the spark plug and a second combustion space around a circumference of a cylinder bore. Further, the first combustion space and the second combustion space are communicated with each other through a small interspace zone where an interspace between the ceiling wall and the top surface of the piston is narrowed. The combustion chamber structure makes it possible to increase compression ratio in a practically effective manner.