Motorcycle Catalyst Arrangement Using Crankcase Space
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Solution Overview
Problem
In motorcycles with moderate engine displacement, the catalyst converter becomes large, making it difficult to arrange compactly while maintaining sufficient ground clearance, as there is no empty space available at the lower side of the crankcase.
Innovation Solution
A catalyst storage chamber is arranged in the exhaust pipe between the exhaust port and muffler, with its axis parallel to the crankshaft, utilizing the space above the crankcase and within the engine cylinder's width, allowing for compact arrangement and rapid catalyst activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the catalyst converter is arranged at the lower side of the crankcase, then the ground clearance is ensured, but the catalyst converter cannot be compactly arranged when the engine displacement is moderate or larger
Solution Approach 1:
The patent changes the spatial arrangement from the conventional lower-side-of-crankcase position to an upper-side position within the engine body, specifically utilizing the space between the cylinder and crankcase. This dimensional relocation allows the catalyst converter to be compactly arranged while maintaining adequate ground clearance, as the catalyst converter is positioned above the horizontal plane extending from the crankcase bottom surface.
Solution Approach 2:
The catalyst converter is nested within the engine body structure, specifically positioned in the space formed by the cylinder, crankcase, and horizontal plane. This nesting approach allows the catalyst converter to be integrated into the existing engine architecture without requiring additional external space, thereby achieving compact arrangement while maintaining ground clearance.
2Quantity of substance
If the catalyst converter size increases proportionally with engine displacement, then the catalyst capacity is sufficient, but the arrangement space becomes insufficient
Solution Approach 1:
The patent utilizes the vertical space within the engine body, specifically the area between the cylinder and crankcase, to accommodate the catalyst converter. This allows the catalyst converter to be positioned in three-dimensional space that would otherwise be unused, enabling sufficient catalyst capacity for moderate and larger engine displacements without requiring additional external arrangement space.
Solution Approach 2:
The space between the cylinder and crankcase, which is typically unused or used for other purposes, is repurposed to house the catalyst converter. This multi-functional use of space allows the same engine structure to simultaneously support both the mechanical components and the emissions control system, accommodating catalyst converters of various sizes depending on engine displacement.
3Temperature
If the catalyst converter is arranged away from the cylinder, then the ground clearance is maintained, but the catalyst activation time increases
Solution Approach 1:
The patent positions the catalyst converter in a specific local region within the engine body - the space between the cylinder and crankcase, above the horizontal plane from the crankcase bottom. This localized positioning ensures the catalyst converter is sufficiently close to the cylinder for rapid heat transfer and activation, while the upper positioning within the engine body maintains adequate ground clearance. The arrangement optimizes the local thermal environment for catalyst activation without compromising overall positional stability.
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 enables a compact catalyst arrangement with minimal ground clearance, rapid catalyst activation, and improved exhaust unit design, including silencing functionality and reduced exposure to traveling wind.
Implementation Method 1
even in a cold engine condition after starting the engine, a catalyst can be rapidly activated by the heat of the cylinder
Implementation Method 2
a catalyst can be rapidly activated by the heat of the cylinder
Data Source
AI summary
An engine has a crankcase, and a cylinder which extends from an upper portion of the crankcase toward a front side. In a space which is formed at an upper side of a horizontal plane which substantially horizontally extends from a bottom surface of the crankcase, a catalyst storage chamber is arranged in such a manner that an axis of the catalyst converter is in a direction of a crankshaft. The space is arranged just below a front surface of the cylinder and forward of a front surface of the crankcase.