Motorcycle Frame Trellis Design Torsional Rigidity
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Solution Overview
Problem
Motorcycle frames with low torsional rigidity experience significant elastic deformations during cornering and braking, leading to delayed handling and a fuzzy feel, which is detrimental to dynamic handling, and increasing rigidity by enlarging frame segments increases mass, which is undesirable.
Innovation Solution
A three-dimensional trellis composite motorcycle frame design with a reduced number of interconnected tubes, featuring a single tube parallel to the upper frame main tubes and the steering head tube, enhancing torsional rigidity by approximately 30% while reducing mass, and incorporating an oil scavenger within the single tube for functional integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the dimensions of individual frame segments are increased to achieve higher torsional rigidity, then the torsional rigidity of the motorcycle frame is improved, but the mass of the motorcycle frame increases
Solution Approach 1:
The frame is divided into multiple tubular segments (head tube, upper tubes, lower tubes, struts) that are interconnected. This segmentation allows each tube to be optimized for its specific structural role while maintaining overall high torsional rigidity without requiring uniform increases in all dimensions, thus controlling mass.
Solution Approach 2:
The frame employs a composite tubular structure with multiple tubes of different diameters and wall thicknesses arranged in a three-dimensional configuration. This composite arrangement creates high torsional rigidity through the collective geometric configuration rather than relying on any single oversized tube, thereby avoiding excessive mass increase.
2Strength
If a traditional multi-tube trellis frame configuration is used to ensure structural integrity, then the strength and rigidity are maintained, but the number of welding operations increases leading to more thermal distortion and longer fabrication time
Solution Approach 1:
Certain non-essential tubes from traditional trellis frame designs are removed or eliminated. The patent identifies and removes redundant tubular elements while retaining the core structural tubes necessary for strength and rigidity, thereby reducing the total number of welding operations and associated thermal distortion.
Solution Approach 2:
The frame is designed with a segmented configuration where tubes are strategically positioned and connected only where structurally necessary. This selective segmentation reduces the overall number of joints and welding operations compared to a dense multi-tube trellis configuration, while still achieving the required structural integrity.
3Ease of operation
If the frame geometry is optimized for dynamic handling and cornering performance, then the handling response is improved, but the frame experiences greater elastic deformations under torsional loading
Solution Approach 1:
Different portions of the frame are designed with locally optimized properties: the head tube region and upper tubes are configured for high torsional rigidity to minimize elastic deformations during cornering, while the lower tubes and struts are optimized for flexibility and geometry to improve dynamic handling and cornering performance. This local differentiation resolves the contradiction between handling and rigidity.
Solution Approach 2:
The frame geometry incorporates dynamic characteristics through its three-dimensional tubular configuration, allowing controlled elastic deformations that improve handling response. The specific arrangement of tubes and struts creates a structure that is rigid enough to maintain stability but flexible enough to respond dynamically to cornering forces, resolving the contradiction between rigidity and handling.
Data Source
AI summary
A motorcycle frame, and motorcycle with the frame as disclosed. There is disclosed a motorcycle frame having tubes extending away from a steering head tube in a three-dimensional trellis composite assembly of frame main tubes, interconnected by frame struts, paired upper and lower frame main tubes oriented, along at least a portion of their lengths, substantially parallel to each other. A single tube is oriented parallel to the lower frame main tubes, and arranged between the upper frame main tubes and the steering head tube.