Spark Arrestor Reverse Flow Channel for Compact Muffler Design
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Solution Overview
Problem
Existing spark arrestors and mufflers in straddle type vehicles, such as ATVs, are undesirably large in size due to the expansion and contraction of exhaust in multiple chambers, compromising both exhaust sound reduction and spark prevention capabilities.
Innovation Solution
A spark arrestor design featuring a cylindrical portion with a mesh-covered opening, a tail pipe, and a guide member that reverses the exhaust flow direction within the cylindrical portion, creating a longer exhaust channel and reducing flow speed, thereby improving sound reduction and spark prevention while minimizing size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If expansion and contraction of exhaust is performed in a spark arrestor mounted to straddle a plurality of expansion chambers provided in a muffler, then exhaust sound reduction capability is improved, but the spark arrestor and muffler become undesirably large in size in the axial direction
Solution Approach 1:
The patent introduces a reverse flow channel that allows exhaust to flow in opposite directions through the spark arrestor. This dimensional change in flow path enables the exhaust to traverse a longer effective path length within the same axial footprint, achieving sound reduction without increasing axial size. The reverse flow channel creates a multi-directional flow pattern that increases the effective length of the exhaust path.
Solution Approach 2:
The spark arrestor is divided into functionally distinct segments: a first flow channel for exhaust intake, a reverse flow channel for opposite-direction flow, and a second flow channel for exhaust discharge. This segmentation allows each channel to be optimized for its specific function while collectively achieving sound reduction through the combined path length without requiring increased axial dimensions.
2Object-affected harmful factors
If the exhaust flow path is lengthened to improve sound reduction, then exhaust sound reduction capability is improved, but the device size increases
Solution Approach 1:
The reverse flow channel enables exhaust to flow in opposite directions through the spark arrestor, creating a multi-dimensional flow path. This allows the exhaust to traverse a longer effective path length within the same volumetric space by utilizing bidirectional flow rather than a unidirectional path, achieving sound reduction without volume increase.
Solution Approach 2:
The reverse flow channel is nested within the existing spark arrestor structure, utilizing the same cylindrical space for both the forward flow channel and the reverse flow channel. This nesting arrangement allows the extended flow path to be contained within the original device boundaries, achieving longer effective path length without increasing overall volume.
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 solution reduces the size of the spark arrestor and muffler while enhancing exhaust sound reduction and spark prevention capabilities by optimizing the exhaust flow path within the cylindrical structure.
Implementation Method 1
a mesh portion (72) that covers the opening (7a)
Implementation Method 2
the exhaust flows outside the cylindrical portion (71) in a first direction along an axis of the cylindrical portion, and the exhaust flows in a channel of the cylindrical portion in a second direction opposite to the first direction
Data Source
AI summary
A spark arrestor mounted on a muffler connected to an exhaust pipe of an engine includes a cylindrical portion including an opening that extends therethrough from the outside to the inside thereof, two cap members that respectively close first and second ends of the cylindrical portion, a mesh portion that covers the opening, and a tail pipe extending from the inside to the outside of the cylindrical portion through the cap member, wherein the exhaust flows outside the cylindrical portion in a first direction, and a channel where the exhaust flows in a second direction opposite to the first direction is provided inside the cylindrical portion.