Spark Plug Auxiliary Chamber Sphere Geometry
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Solution Overview
Problem
The existing spark plug design, where the flame jets out from the through hole at the spark gap position before the pressure in the auxiliary chamber is sufficiently increased, results in a low flame jetting speed and poor fuel economy due to insufficient flame spread in the combustion chamber.
Innovation Solution
The spark plug design includes a center electrode, a ground electrode, and a plug cover forming an auxiliary chamber with 60% or more of its volume within a sphere centered at the spark discharge point, increasing pressure and enhancing flame jetting speed and spread within the combustion chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the through hole is provided at the position of the spark gap and another through hole is provided at the frontmost side of the auxiliary chamber, then the flame can jet out from the through holes, but the flame jetting speed is insufficient because the pressure in the auxiliary chamber is not sufficiently increased before flame jetting
Solution Approach 1:
The patent applies local quality by strategically positioning the through hole at a specific location on the auxiliary chamber - specifically at a position where a sphere (centered at the midpoint of the line segment connecting the center electrode and ground electrode, and tangent to the inner open end of the through hole) contains 60% or more of the auxiliary chamber volume. This localized geometric constraint ensures that the flame generates sufficient pressure within the auxiliary chamber before jetting out, thereby increasing the flame jetting speed and improving fuel economy.
2Temperature
If the flame jets out from the through holes before the pressure in the auxiliary chamber is sufficiently increased, then the flame can exit the auxiliary chamber, but the flame does not sufficiently spread in the combustion chamber
Solution Approach 1:
The patent uses local quality by defining a specific geometric relationship between the auxiliary chamber and the through hole position. The sphere containing 60% or more of the auxiliary chamber volume ensures that the flame remains confined long enough to generate sufficient pressure and temperature, enabling complete combustion of the fuel-air mixture before the flame jets out to the combustion chamber, thus improving both combustion efficiency and fuel economy.
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 significantly improves fuel economy by increasing the flame jetting speed and ensuring efficient combustion chamber coverage, with optional features like a tubular insulator, metal shell, and packing further enhancing pressure and fuel efficiency.
Implementation Method 1
a gap for spark discharge is formed between the center electrode and the ground electrode
Implementation Method 2
the pressure in the auxiliary chamber is increased by the flame
Data Source
AI summary
A spark plug includes: a center electrode; a ground electrode that is provided such that a gap for spark discharge is formed between the center electrode and the ground electrode; and a plug cover covering the center electrode and the ground electrode from a front side to form an auxiliary chamber, the plug cover being provided with a through hole, wherein 60% or more of the auxiliary chamber is present in a sphere. The sphere t has a center at a midpoint of a line segment connecting the center electrode and the ground electrode at a shortest distance on an axial line of the center electrode and is in contact with a point located closest from the center on an inner open end of the through hole is imagined.