Combustion Chamber Guide Portion for Tumble Flow Collapse
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Solution Overview
Problem
In spark-ignition internal combustion engines, the tumble flow tends to collapse at higher engine speeds, leading to reduced flow rates near the ignition plug, uneven air/fuel mixture distribution, and subsequent non-uniform flame propagation, which can result in deteriorated ignition performance and potential issues like knocking or misfiring.
Innovation Solution
A combustion chamber structure with a guide portion protruding from the upper wall, shaped to disperse airflow and prevent tumble flow collapse, ensuring consistent air/fuel mixture distribution and reducing the likelihood of non-uniform flame propagation by guiding airflow through the central portion in an intake-exhaust direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine speed is increased, then the power output is improved, but the tumble flow velocity increases causing tumble flow collapse
Solution Approach 1:
The guide portion acts as an intermediary structure between the intake ports and the ignition plug region. It mediates the high-velocity tumble flow by providing a physical barrier that redirects and dissipates the flow energy, preventing direct collapse while maintaining the beneficial mixing effects at higher engine speeds
2Power
If the tumble flow velocity is increased, then the power output is improved, but the airflow distribution uniformity deteriorates
Solution Approach 1:
The guide portion creates local flow control zones with different characteristics. The region around the guide portion experiences flow dispersion and redirection, while other regions maintain their original flow patterns. This local modification ensures uniform overall distribution even at high velocities where global flow control would be insufficient
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 guide portion effectively prevents tumble flow collapse and ensures uniform airflow distribution, enhancing ignition performance, reducing the risk of knocking, and allowing for increased EGR gas introduction without misfiring, thereby improving combustion efficiency and stability.
Implementation Method 1
a guide portion that protrudes from the upper wall of the combustion chamber and is shaped to guide airflow passing through a central portion of the combustion chamber in an intake-exhaust direction of the combustion chamber while dispersing the airflow around the guide portion
Implementation Method 2
the guide portion that protrudes from the upper wall of the combustion chamber makes it possible to curb collapse of the tumble flow in the compression stroke, which would otherwise be caused by increase of the velocity of the tumble flow
Data Source
AI summary
A combustion chamber structure for a spark-ignition internal combustion engine includes a combustion chamber, an ignition plug, and a guide portion. The combustion chamber is configured to produce tumble flow that swirls in an axial direction of a cylinder. The ignition plug is disposed in a central portion of an upper wall of the combustion chamber. The guide portion protrudes from the upper wall of the combustion chamber, and is configured to guide airflow passing through the central portion of the combustion chamber in an intake-exhaust direction of the combustion chamber while dispersing the airflow around the guide portion.