Spark Plug Positioning for Combustion Chamber Squish Flow Management
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Solution Overview
Problem
Conventional spark-ignition engines face increased hydrocarbon content in exhaust gas due to incomplete combustion, caused by the spark discharge section being directly hit by the largest squish flow at compression top dead center, preventing flame propagation.
Innovation Solution
The spark discharge section is positioned not to overlap the central virtual line when viewed from the cylinder center axis, and the engine design includes specific valve and port configurations to enhance squish flow direction and scavenging efficiency, ensuring smooth flame propagation and reducing hydrocarbon content in exhaust gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the spark discharge section is disposed at the vicinity of compression top dead center directly hit by the largest squish flow, then the squish flow can cause disturbance of fuel-air mixture and increase flame propagation speed to prevent engine knocking, but the spark discharge section is blown out by the largest squish flow causing small fire source and preventing flame propagation, increasing hydrocarbon content in exhaust gas
Solution Approach 1:
The spark plug is positioned asymmetrically in the combustion chamber, specifically in the area away from the central virtual line that passes through the squish area maximum-width section. This asymmetric positioning ensures that the spark discharge section is not directly in the path of the largest squish flow, preventing the spark plug tip from being blown out while still enabling effective flame propagation throughout the combustion chamber.
2Object-generated harmful factors
If the spark discharge section is positioned not to overlap the central virtual line, then the largest squish flow does not directly hit the spark discharge section preventing small fire source and incomplete combustion, but the flame propagation speed may be reduced
Solution Approach 1:
The combustion chamber is designed with differentiated local qualities: the squish area is configured to generate controlled squish flow, while the spark plug positioning area is specifically designed to avoid direct impact from the largest squish flow. The combustion chamber recessed section and valve port arrangements create localized zones that optimize both flame propagation and prevent spark plug tip erosion from direct squish flow impact.
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 reduces hydrocarbon content in exhaust gas by preventing direct hit of the largest squish flow on the spark discharge section, promoting complete combustion and improving scavenging efficiency, thereby minimizing hydrocarbon emissions.
Implementation Method 1
a squish flow is ejected from a squish area formed between the cylinder head-side squish surface and the piston head-side squish surface toward the center of the combustion chamber recessed section
Implementation Method 2
spark discharge of a spark plug
Implementation Method 3
flame generated by spark discharge of a spark plug
Data Source
AI summary
A spark-ignition engine capable of reducing the content of hydrocarbon in exhaust gas is provided. When viewed from a direction parallel to a cylinder center axis, given a central virtual line passing a squish area maximum-width section and the center of a combustion chamber recessed section, and one area a and the other area b divided by the central virtual line, an intake valve port or an exhaust valve port is opened in one area of any opposed section of opposed sections of the combustion chamber recessed section. A spark-plug attachment hole is formed in the other area of the opposed section, such that, when viewed from the direction parallel to the cylinder center axis, a spark discharge section at a tip of a spark plug does not overlap the central virtual line.