Motorcycle Silencer Layout Flexibility via Catalyst Decoupling
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Solution Overview
Problem
Existing silencers for large-sized motorcycles with low-speed type V-type engines are restricted in design freedom due to the need for a straight inner cylinder to fix the catalyst, leading to limitations in exhaust efficiency and layout when reducing the number of silencers from two to one for weight reduction.
Innovation Solution
A silencer design featuring a head with a catalyst holding portion and a tapered drum portion, where the catalyst is inserted into a catalyst inserted member fixed to a catalyst fixed member positioned upstream, allowing for a double tube structure with a sound absorbing material and partition plate to manage exhaust gas flow and noise reduction, enabling a more flexible layout without restricting the inner cylinder shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the catalyst is fixed to the inner peripheral surface of the inner cylinder, then the catalyst is firmly fixed, but the inner cylinder must be a straight tube which restricts design freedom and layout flexibility
Solution Approach 1:
The silencer is divided into a head portion and a drum portion, with the catalyst fixing function separated from the inner cylinder. The catalyst fixed member is provided on the head portion rather than on the inner cylinder, allowing the inner cylinder to be designed freely without being constrained by catalyst fixation requirements.
Solution Approach 2:
A catalyst fixed member is introduced as an intermediary component to fix the catalyst. This fixed member includes a catalyst inserted member that can be positioned upstream of the drum portion, decoupling the catalyst fixation function from the inner cylinder structure and enabling greater design freedom.
2Productivity
If the silencer diameter is increased to improve exhaust efficiency, then exhaust efficiency increases, but layout restrictions are aggravated
Solution Approach 1:
The catalyst fixed member extends in the longitudinal direction upstream of the drum portion, utilizing the space dimension before the drum to provide catalyst fixation. This allows the silencer to have a larger diameter for improved exhaust efficiency without compromising layout flexibility, as the fixation function is positioned in a different spatial zone.
3Weight of moving object
If the number of silencers is reduced from two to one for weight reduction, then weight decreases, but exhaust efficiency decreases
Solution Approach 1:
The head portion and drum portion are merged into a single integrated silencer structure that combines catalyst fixation functionality with expanded exhaust flow capacity. This single silencer replaces two separate silencers, reducing weight while maintaining or improving exhaust efficiency through the optimized integrated design.
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 relaxes layout restrictions, improves exhaust efficiency, and maintains sound damping characteristics while allowing for a larger diameter silencer, providing a more aesthetically pleasing and functional solution for single muffler systems on large-sized motorcycles.
Implementation Method 1
a sound absorbing material filled between the outer and inner cylinders
Implementation Method 2
a catalyst is mounted in an exhaust silencer and exhaust gases from an engine are purified by contacting the catalyst when passing through the exhaust silencer
Data Source
AI summary
A silencer for a motorcycle with relaxed layout restrictions has a drum portion connected to a head. A conduit extends through the drum portion in a direction of connection. The drum portion decreases in cross sectional area toward a downstream side. A catalyst holding portion formed in the head has a catalyst fixed member to which a catalyst inserted member is fixed at a position upstream of the drum portion. A catalyst is inserted into the catalyst inserted member.