Spark Plug Cover Geometry for Stable Fuel Gas Entry
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Solution Overview
Problem
Existing spark plugs suffer from unstable combustion due to insufficient fuel gas entry through the injection holes, leading to incomplete ignition and loss of momentum, which affects combustion stability.
Innovation Solution
The spark plug design includes a cover with injection holes where the distance between the intersection point of the outer surface and the front end is 1 mm or more, along with specific angles and curvature radii to ensure a sufficient fuel gas flow, preventing merging and enhancing ignition stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the injection hole is positioned close to the front end of the cover, then the fuel gas can enter the cover more easily, but the fuel gas flow merges with the large flow moving along the front end, reducing the amount of fuel gas entering through the injection hole
Solution Approach 1:
The patent changes the geometric parameter of the injection hole position by specifying that the distance from the first intersection point to the front end of the cover must be 1 mm or more. This parameter change prevents the harmful merging of fuel gas flows while ensuring sufficient fuel gas entry, thereby resolving the contradiction between quantity of substance and composition stability.
2Reliability
If the fuel gas flow is insufficient, then the ignition may fail to occur, but increasing the fuel gas flow requires optimizing the injection hole position and geometry which complicates the design
Solution Approach 1:
The patent establishes specific parameter ranges for the injection hole position (distance ≥ 1 mm) and geometry (angle between 57° and 123°) to ensure reliable ignition. These parameter specifications provide a clear design guideline that achieves ignition reliability without excessive structural complexity.
Solution Approach 2:
The patent specifies that the distance should be 1 mm or more, which is a minimum threshold that ensures sufficient fuel gas entry for reliable ignition. This partial action approach provides a practical design criterion that is easier to implement than complex flow control mechanisms.
3Quantity of substance
If the distance is increased to prevent flow merging, then the fuel gas entry is improved, but the distance cannot be excessive as it may affect the overall compactness of the spark plug
Solution Approach 1:
The patent optimizes the distance parameter by setting it to 1 mm or more, which is sufficient to prevent flow merging while maintaining compact dimensions. This balanced parameter selection resolves the contradiction between quantity of substance and length of stationary object.
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 ensures a stable fuel gas concentration and ignition, improving combustion stability by ensuring adequate fuel gas entry and reducing energy loss, thereby enhancing combustion efficiency.
Implementation Method 1
ignites the fuel gas that has entered the cover through the injection hole
Implementation Method 2
burns the fuel gas in the combustion chamber
Implementation Method 3
injects a gas flow including the generated flame into a combustion chamber through the injection hole
Data Source
AI summary
A spark plug includes: a metal shell having a cylindrical shape extending along an axial line, the metal shell including a front end being open; and a cover having one or more injection holes passing through the cover, the cover closing the front end of the metal shell. In at least one of the one or more injection holes, in a section including a center line of the at least one injection hole and parallel to the axial line, a distance in an axial direction between, of two intersection points at which an outer surface of the cover and the at least one injection hole intersect, a first intersection point on a front end side and a front end of the cover is 1 mm or more.