Trapezoidal Swing Arm Cross Member for Weight Reduction
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Solution Overview
Problem
The existing swing arm suspension systems in vehicles require high rigidity for the cross member to protect the drive shaft from road debris, which increases weight and complicates the design.
Innovation Solution
A trapezoidal cross member is integrated into the swing arm structure, with a broader bottom and narrower top, allowing it to be contained within the arm bodies and reducing the need for excessive rigidity, while being positioned below the drive shaft to prevent contact with the road and shield the drive shaft from debris.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cross member is made to project downward to prevent contact with road surface, then the drive shaft is protected from scattering stones, but the cross member requires high rigidity which increases weight
Solution Approach 1:
The cross member employs a trapezoidal cross-section with different width characteristics at different locations: the bottom portion has a wider width for protection, while the upper portion has a narrower width for weight reduction. This local differentiation of structural properties allows the cross member to provide adequate protection where needed while minimizing overall weight.
Solution Approach 2:
The cross member is designed with a trapezoidal cross-section rather than a uniform rectangular shape, utilizing the vertical dimension to create a gradient in width from bottom to top. This dimensional approach allows the protective function to be concentrated at the bottom portion while reducing material usage in the upper portion.
2Reliability
If the cross member is made with high rigidity to prevent contact with road surface, then the drive shaft is protected, but the device complexity increases
Solution Approach 1:
The cross member employs a trapezoidal cross-section with different width characteristics at different locations: the bottom portion has a wider width for protection, while the upper portion has a narrower width for weight reduction. This local differentiation of structural properties allows the cross member to provide adequate protection where needed while minimizing overall weight.
3Weight of moving object
If the cross member is contained within arm bodies to reduce weight, then weight is reduced, but the protectability from road debris is compromised
Solution Approach 1:
The cross member employs a trapezoidal cross-section with different width characteristics at different locations: the bottom portion has a wider width for protection, while the upper portion has a narrower width for weight reduction. This local differentiation of structural properties allows the cross member to provide adequate protection where needed while minimizing overall weight.
Solution Approach 2:
The cross member is designed with a trapezoidal cross-section rather than a uniform rectangular shape, utilizing the vertical dimension to create a gradient in width from bottom to top. This dimensional approach allows the protective function to be concentrated at the bottom portion while reducing material usage in the upper portion.
Data Source
AI summary
To provide a swing arm structure capable of suppressing the required rigidity of a cross member to a low level to reduce the weight of the cross member. In a swing arm structure, a swing arm includes a pair of left and right arm bodies with a cross member spanning therebetween. Ends of the swing arm suspend rear wheels. A rear wheel-driving rear drive shaft, connected to a rear final reduction gear unit, is placed above the cross member. As viewed laterally, the cross member is contained within the profile of each arm body and is formed to be trapezoidal in section such that its bottom portion is broader than its upper portion.