Motorcycle Exhaust Muffler Lateral Inlet Cross-Section Ratio
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Solution Overview
Problem
Conventional exhaust devices for motorcycle engines face limitations in increasing the noise reduction efficiency of mufflers due to a restricted cross-section ratio, which hinders effective noise reduction.
Innovation Solution
The exhaust device incorporates an exhaust chamber with an inlet facing backward and an outlet facing sideways, connected to a muffler inlet on its lateral surface, increasing the cross-section ratio by enlarging the passage-sectional area of the expansion chamber, and includes a separator within the muffler to further enhance noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the inlet of the muffler is provided at the leading end portion facing the back and forth direction, then the structure is simple, but the cross-section ratio cannot be increased sufficiently
Solution Approach 1:
The patent changes the orientation of the muffler inlet from the longitudinal direction to the lateral direction. The inlet passage is formed at the lateral surface of the front portion of the muffler body, allowing exhaust gas to enter from the side rather than from the front. This dimensional change enables the expansion chamber to have a larger cross-sectional area perpendicular to the exhaust flow, thereby increasing the cross-section ratio without complicating the overall structure.
2Object-affected harmful factors
If the passage-sectional area of the expansion chamber is increased to improve noise reduction efficiency, then the cross-section ratio increases, but the muffler size increases
Solution Approach 1:
The patent increases the passage-sectional area of the expansion chamber by utilizing the lateral dimension of the muffler body. Instead of expanding the chamber in the longitudinal direction (which would increase muffler length), the expansion is achieved by forming a large cross-section perpendicular to the exhaust flow at the lateral surface. This allows the expansion chamber to have a large area while keeping the overall muffler volume compact.
3Area of moving object
If the exhaust chamber is disposed between the lower rear side of the engine and the rear wheel, then the vertical width of the exhaust chamber is sufficient, but the ground clearance may be reduced
Solution Approach 1:
The patent positions the exhaust chamber to utilize the lateral space between the engine and rear wheel rather than solely relying on vertical space. By orienting the inlet passage laterally and allowing the exhaust chamber to extend in the lateral dimension, the design achieves sufficient vertical width for the expansion chamber while maintaining adequate ground clearance, as the chamber does not need to extend far downward.
Data Source
AI summary
A muffler for efficiently reducing noise. Front side exhaust pipes and rear side exhaust pipes extend from front cylinders and rear cylinders, respectively, of a V-type water-cooled 4-cylinder engine and are operatively connected to a catalyst chamber disposed below a crankcase. The catalyst chamber is connected to an exhaust chamber located to the rear thereof in which exhaust gas is expanded. An outlet pipe laterally projects from a lateral surface of a rear end portion of the exhaust chamber and is connected to a front pipe projecting from the lateral surface of the front portion of a muffler. The front pipe is transversely inserted into the muffler to increase a cross-section ratio, thereby efficiently reducing noise.