Motorcycle Exhaust Catalyst Orientation and Air Guide
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Solution Overview
Problem
Existing exhaust devices for saddle riding vehicles face challenges in cooling catalysts using traveling air while preventing interference with the ground during banking and minimizing vehicle height, as traditional arrangements either interfere with the ground or complicate cooling.
Innovation Solution
The exhaust device positions the catalyst device with its longitudinal direction in the vehicle width direction, below the cylinder, and uses an undercover with an air guide rib to direct traveling air to the catalyst, ensuring effective cooling and preventing ground interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the catalyst device is arranged between the fuel tank and the vehicle body cover to be cooled by traveling air, then the catalyst cooling effect is improved, but the arrangement layout is restricted and the vehicle height increases to avoid ground interference during banking
Solution Approach 1:
The catalyst device is rotated 90 degrees so its longitudinal direction extends in the vehicle width direction rather than the vehicle longitudinal direction. This dimensional change allows the catalyst device to be positioned centrally below the cylinder, utilizing the vehicle width dimension to achieve both effective cooling by traveling air and avoidance of ground interference during banking without increasing vehicle height
2Length of stationary object
If the catalyst device is arranged at an intermediate position in the vehicle width direction to suppress vehicle height increase, then the vehicle height is reduced, but it becomes difficult to cool the catalyst by traveling air as vehicle body cover and equipment are arranged in front
Solution Approach 1:
An air guide rib is introduced as an intermediary structure on the undercover bottom surface. This air guide rib directs traveling air from the front toward the catalyst device, serving as a mediator that enables effective cooling despite the catalyst device being positioned centrally in the vehicle width direction where it would otherwise be shielded from direct airflow by the vehicle body cover and equipment
3Ease of manufacture
If the catalyst device is positioned on a lateral side of the fuel tank to connect the exhaust pipe in the longitudinal direction, then the exhaust pipe connection is simplified, but the catalyst device interferes with the ground when the vehicle banks
Solution Approach 1:
The catalyst device is rotated 90 degrees so its longitudinal direction extends in the vehicle width direction rather than the vehicle longitudinal direction. This dimensional change repositions the catalyst device centrally below the cylinder, away from the lateral sides where ground interference occurs during banking, while the exhaust pipe is configured to connect to both ends of the catalyst device accommodating this orientation
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 configuration effectively cools the catalyst using traveling air while maintaining a required bank angle without increasing vehicle height, by positioning the catalyst device centrally and using the undercover to guide air to the catalyst device.
Implementation Method 1
the undercover has a bottom surface formed thereon with an upright air guide rib extending in the longitudinal direction of the vehicle; and the air guide rib has a rear end directed toward the catalyst device as viewed in a plan view
Implementation Method 2
the catalyst device is arranged such that at least a part of the catalyst device is disposed below the cylinder as viewed in a side view of the vehicle... the catalyst loaded in the catalyst device to be cooled by traveling air
Data Source
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AI summary
An exhaust device of a saddle riding vehicle including: a swing-type power unit 3 swingably supported on a body frame 2 by way of a link member 24, with a cylinder axis C inclined frontward in an approximately horizontal direction; an exhaust pipe 6 connected to a cylinder head 43; a catalyst device 7 interposed in the middle of the exhaust pipe 6; and a foot placing portion 1C positioned in front of the power unit 3. The exhaust pipe 6 is connected to both ends of the catalyst device 7 in its longitudinal direction, and the catalyst device 7 is arranged such that at least a part thereof is disposed below a cylinder 42 as viewed in a side view, and the catalyst device 7 has its longitudinal direction oriented in a width direction of the vehicle. An undercover 10e is arranged below a foot placing portion 1C and in front of the catalyst device 7, and the undercover 10e has its bottom surface rear end 84 directed toward the catalyst device 7. The exhaust device can cool a catalyst in the catalyst device by making use of traveling air while preventing the catalyst device from interfering with a ground when the vehicle banks.