Swing Arm Drive Shaft Nesting for Motorcycle Rigidity
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Solution Overview
Problem
Two-wheeled motor vehicles face challenges in achieving sufficient rigidity of the swing arm while maintaining an improved outer appearance, as existing designs often compromise on either structural integrity or aesthetics due to exposed drive shafts and inadequate torsional characteristics.
Innovation Solution
A two-wheeled motor vehicle design featuring a vehicle body frame with a pivot shaft, a single swing arm surrounding a drive shaft that is positioned below the imaginary line connecting the pivot shaft and rear wheel axle, with a partition member in the front half region of the swing arm to enhance rigidity and a recessed portion underneath the front end of the swing arm covered by a resin-made cover member, ensuring the drive shaft is not exposed and minimizing weight increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the drive shaft is exposed outwardly for structural simplicity, then the manufacturing cost is reduced, but the outer appearance deteriorates
Solution Approach 1:
The drive shaft is nested within the swing arm structure, specifically positioned inside the hollow section of the swing arm. This nesting arrangement allows the drive shaft to be concealed within the swing arm's internal cavity, eliminating the need for external exposure while maintaining structural integrity and achieving improved outer appearance without significant manufacturing complexity increase.
2Weight of moving object
If the swing arm vertical width is reduced to minimize weight, then the weight is decreased, but the fastening rigidity of the pivot shaft deteriorates
Solution Approach 1:
The swing arm employs local quality enhancement through strategic reinforcement: a rib structure is added at the pivot shaft fastening region to locally increase stiffness and fastening rigidity, while the overall swing arm vertical width is minimized to reduce weight. This localized reinforcement approach ensures that strength is concentrated where needed (at the pivot shaft) without uniformly increasing the swing arm's weight.
Solution Approach 2:
The swing arm utilizes composite construction combining aluminum alloy base material with strategically placed reinforcement ribs and partition members. This composite approach allows the main body to remain lightweight while specific regions (pivot shaft area, drive shaft surrounding area) gain enhanced rigidity through the integrated reinforcement structures, achieving optimal balance between weight and fastening rigidity.
3Stability of the object's composition
If the swing arm rigidity is enhanced to improve structural stability, then the structural stability is improved, but the torsional characteristics deteriorate due to increased weight
Solution Approach 1:
The swing arm implements local quality differentiation through a partition member that divides the hollow section into upper and lower spaces. This partition structure strategically enhances rigidity in specific regions (where the drive shaft is surrounded and at the pivot shaft area) while maintaining lighter weight in other areas. The rib structures are positioned to provide local reinforcement without uniformly increasing overall weight, thus preserving torsional characteristics.
Solution Approach 2:
The swing arm employs composite material strategy combining aluminum alloy with integrated reinforcement elements (partition members and ribs). This allows the structure to achieve high structural stability through strategically placed reinforcement zones while keeping the overall weight minimized. The composite design ensures that rigidity enhancement is concentrated where structurally critical, maintaining optimal torsional characteristics for cornering performance.
4Strength
If the partition member is added to enhance rigidity, then the rigidity of the swing arm is improved, but the device complexity increases
Solution Approach 1:
The partition member is merged with the drive shaft housing structure, where the partition wall simultaneously serves as the inner surface of the hollow section and the surrounding structure for the drive shaft. This merging approach integrates the rigidity-enhancing partition function with the existing drive shaft containment structure, avoiding the need for separate, additional components and thus minimizing the increase in device complexity while achieving the rigidity enhancement goal.
Data Source
AI summary
A two-wheeled motor vehicle provided with a drive shaft (32) rotatably supported by a swing arm (28) rockable on a pivot shaft (27). The longitudinal center axis (32J) of the drive shaft (32) is located below a line (28C) interconnecting the pivot shaft (27) and an axle (40). The drive shaft (32) is surrounded by the swing arm (28).