Motorcycle Cross Member Rigidity Weight Trade-off
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Solution Overview
Problem
Existing body frame reinforcing structures for saddle riding vehicles enhance rigidity but result in increased vehicle weight, and they are prone to twisting during braking while turning.
Innovation Solution
A body frame reinforcing structure that includes a cross member with multiple mounted portions on the down frames, featuring cut-out portions and arc-shaped corner portions, allowing for enhanced rigidity and reduced weight, with the ability to removably attach and accommodate a wire harness, and providing protection for vehicle components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the frame plate thickness is increased to enhance the rigidity of the body frame, then the rigidity is improved, but the vehicle weight increases
Solution Approach 1:
The cross member is divided into multiple segments with mounted portions at different locations along its length. These segmented mounted portions are selectively coupled to the down frames at optimized positions, allowing rigidity enhancement without requiring increased plate thickness throughout the entire structure.
Solution Approach 2:
The cross member is constructed as a composite structure combining the cross member body with multiple mounted portions that are coupled to the down frames. This composite arrangement creates a reinforced structure that achieves higher rigidity without proportionally increasing the weight of individual components.
2Stability of the object's composition
If a cross member is added to couple the down frames to enhance rigidity, then the body frame stability is improved, but the device complexity increases
Solution Approach 1:
The cross member serves multiple functions simultaneously: it couples the down frames to enhance rigidity, provides mounted portions for positioning various components, and includes cut-out portions to accommodate wire harnesses. This multi-functionality reduces the need for separate structural elements, thereby limiting the increase in device complexity.
Solution Approach 2:
The cross member integrates multiple functions into a single structural component. The mounted portions and cut-out portions are incorporated directly into the cross member design, merging support, positioning, and wiring accommodation functions into one element rather than requiring separate components.
3Strength
If multiple mounted portions are added to the cross member to enhance rigidity distribution, then the flexural and torsional rigidity are improved, but the manufacturing complexity increases
Solution Approach 1:
The corner portions of the cut-out portions in the cross member are formed with arc shapes rather than sharp corners. This curvature design reduces stress concentration at the corners and simplifies the manufacturing process compared to creating sharp angular features, while still maintaining the structural integrity and rigidity enhancement benefits.
Data Source
AI summary
A motorcycle having a body frame reinforcing structure includes a right and left pair of down frames supporting an engine in a body frame. The right and left down frames are coupled using the cross member. The cross member includes a plurality of mounted portions mounted to the right and left respective down frames.