Multipoint Ignition Device Flame Propagation Uniformity
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Solution Overview
Problem
In multipoint ignition devices, the propagation speed of flames from ignition gaps is uneven due to varying cooling effects from the combustion chamber wall, leading to inconsistent burning times for air-fuel mixtures.
Innovation Solution
The distance between ignition gaps and the combustion chamber wall is varied by adjusting the projection amount of electrode pairs and/or forming bowl-shaped indentations to ensure uniform flame propagation speed across the chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple electrode pairs are disposed around the cylinder opening portion, then combustion of the air-fuel mixture in the peripheral edge portions of the combustion chamber is promoted and engine output is improved, but the propagation speed of flames from each ignition gap becomes uneven due to varying cooling effects from the combustion chamber wall
Solution Approach 1:
The patent applies local quality by varying the distance between each ignition gap and the combustion chamber wall according to its position. Specifically, ignition gaps are positioned at different distances from the wall to compensate for local variations in cooling effects. This ensures that each flame experiences a uniform effective cooling environment despite the non-uniform geometry of the combustion chamber, thereby achieving uniform flame propagation speeds across all ignition points while maintaining the power benefits of multiple ignition gaps.
2Speed
If the distance between ignition gaps and the combustion chamber wall is varied to achieve uniform flame propagation speed, then flame propagation uniformity is improved, but the device structure becomes more complex
Solution Approach 1:
The patent employs asymmetry by intentionally creating non-uniform distances between different ignition gaps and the combustion chamber wall. This asymmetric arrangement is designed to compensate for the asymmetric cooling effects experienced by flames at different positions in the combustion chamber. By breaking the symmetry of equal spacing, the system achieves uniform flame propagation characteristics despite the structurally asymmetric configuration.
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 approach allows flames to propagate quickly and uniformly throughout the combustion chamber, reducing the time required to burn the air-fuel mixture.
Implementation Method 1
a plurality of electrode pairs constituting ignition gaps are disposed around a cylinder opening portion such that an air-fuel mixture in a combustion chamber is ignited from the plurality of ignition gaps
Implementation Method 2
the propagation speed of the flame that grows from each ignition gap receives a cooling effect (extinguishing action) from the wall surface of the combustion chamber
Implementation Method 3
combustion of the air-fuel mixture in the peripheral edge portions of the combustion chamber is promoted, enabling improvements in engine output and fuel economy
Data Source
Figure 1~2
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AI summary
A plurality of electrode pairs (P1 to P8) are caused to project from a side wall of a combustion chamber (2) of an engine, and a distance between ignition gaps (G1 to G8) and the side wall of the combustion chamber (2) is varied according to the positions of the plurality of electrode pairs (P1 to P8).