Straddled Vehicle Tensioner Spring Nesting for Compact Engine Layout
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Solution Overview
Problem
In straddled vehicles, the need to compactly dispose the intake system and engine leads to a challenge where reducing the size of the tensioner protruding from the engine results in increased engine size, reducing storage box capacity and degrading foot grounding properties due to increased seat height.
Innovation Solution
A straddled vehicle design where the tensioner is positioned between the intake pathway and engine, with a spring system split between an outer and inner accommodation portion, allowing for a smaller protrusion while maintaining sufficient length, thus preventing engine size increase and maintaining storage box capacity and foot grounding properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the casing is shortened to reduce the amount of tensioner protruding from the engine, then the protrusion amount is reduced, but the spring must be shortened resulting in increased outer diameter and radial size of the casing, which increases engine size
Solution Approach 1:
The spring is repositioned from being entirely within the first accommodation portion (outside engine) to being disposed inside both the first accommodation portion and the second accommodation portion (inside engine). This spatial redistribution allows the spring to maintain sufficient length for proper tensioning function while the tensioner casing can be shortened, reducing protrusion without increasing engine radial size.
Solution Approach 2:
The spring is nested within the second accommodation portion that is disposed inside the engine, while still extending into the first accommodation portion outside the engine. This nested arrangement allows the spring to utilize the internal engine space, enabling the tensioner to protrude less while maintaining spring functionality and avoiding engine size increase.
2Length of moving object
If the engine size is increased to accommodate a longer spring, then the spring can maintain sufficient length, but the storage box capacity is reduced and the seat height increases degrading foot grounding properties
Solution Approach 1:
The spring is repositioned to extend into the second accommodation portion inside the engine, utilizing the internal engine space rather than requiring the engine external dimensions to increase. This allows the spring to maintain sufficient length for proper tensioning function while the engine external dimensions remain compact, preserving storage box capacity and seat height.
3Force
If the spring outer diameter is increased to compensate for shortened length, then the spring can exert equivalent load, but the rate of change in outer diameter to displacement increases requiring larger radial casing size
Solution Approach 1:
The spring is repositioned to utilize the second accommodation portion inside the engine, allowing it to maintain its original length and winding count. This eliminates the need to increase the spring's outer diameter to compensate for shortening, thereby maintaining the original rate of change in outer diameter to displacement and avoiding the need for larger radial casing size.
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 reduces the tensioner's protrusion from the engine, allowing for a compact engine and intake pathway arrangement, inhibiting storage box capacity reduction and maintaining foot grounding properties, enhancing durability and maintenance accessibility.
Implementation Method 1
The spring urges the first shaft to rotate the first shaft
Implementation Method 2
The rotary shaft and the thrust shaft are screwed with each other through threads
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A first shaft includes a first threaded portion and is at least in part disposed inside a first accommodation portion. A second shaft is at least in part disposed inside a second accommodation portion, and is moved in an axis direction of a tensioner in accordance with rotation of the first shaft. The second shaft includes a second threaded portion and a distal end. The second threaded portion is screwed with the first threaded portion. The distal end protrudes from the second accommodation portion into an engine. A spring urges the first shaft to rotate the first shaft. As seen in a vehicle plan view, the tensioner at least in part overlaps with an intake pathway portion. The spring is disposed inside the first accommodation portion and the second accommodation portion.