Motorcycle Rear Swing Arm Support Rigidity via Vertical Spacing
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Solution Overview
Problem
Existing motorcycle designs face challenges in achieving lightweight construction while maintaining sufficient supporting rigidity for the rear swing arm, often requiring larger diameters or lengths of components to enhance rigidity, which increases weight.
Innovation Solution
The support portion for the rear swing arm is positioned apart from the drive shaft and at the same height as the rear wheel axis, with a universal joint and a shaft-length variable mechanism that includes a boot to prevent foreign matter intrusion, allowing for adjustable shaft length and improved heat management, thereby enhancing rigidity and reducing weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the width of the head portion or the length of the pivot shaft is increased to increase supporting rigidity, then the supporting rigidity is improved, but the weight of the swing arm is increased
Solution Approach 1:
The patent positions the support portion at a location spaced apart from the drive shaft in the vertical dimension (as viewed from the side view), rather than increasing the horizontal width of the head portion or the length of the pivot shaft. This spatial reconfiguration allows the support portion to be extended in length without interfering with the drive shaft, thereby increasing supporting rigidity while avoiding the weight penalty associated with enlarging the swing arm components in traditional dimensions.
2Strength
If the diameter of the head portion or the diameter of the pivot shaft is increased to ensure supporting rigidity, then the supporting rigidity is improved, but the weight of the swing arm is increased
Solution Approach 1:
Instead of increasing the diameter of the head portion or pivot shaft to achieve the desired supporting rigidity, the patent extends the length of the support portion by positioning it spaced apart from the drive shaft. This dimensional shift from radial expansion to axial extension allows the support portion to achieve sufficient rigidity through increased length rather than increased diameter, thereby maintaining a lighter swing arm weight.
3Strength
If the length of the support portion is increased to enhance supporting rigidity, then the supporting rigidity is improved, but interference with the drive shaft occurs
Solution Approach 1:
The patent resolves the spatial interference issue by repositioning the support portion in the vertical dimension, spacing it apart from the drive shaft as viewed from the side view. This allows the support portion to be extended in length to enhance supporting rigidity while maintaining clear separation from the drive shaft, avoiding the complexity and interference problems that would arise from traditional configurations.
Data Source
AI summary
A motorcycle includes a vehicle body frame, a rear swing arm which is mounted on a vehicle body frame in a rockable manner by way of a pivot shaft, and a rear wheel which is pivotally supported on a rear portion of the rear swing arm and is rotated by a driving force of a drive shaft. The pivot shaft which constitutes a support portion and an axis of the rear wheel axle are arranged at the substantially same height. The drive shaft is arranged at a position upwardly spaced-apart from the drive shaft, that is, above the pivot shaft. The drive shaft includes a shaft-length variable mechanism which can change a length of the shaft. The resulting configuration provides a motorcycle having reduce weight while maintaining support rigidity of the rear swing arm.