Layered Resin Cover for Straddled Vehicles Weight Reduction
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Solution Overview
Problem
Existing exterior cover structures for straddled vehicles, while promoting weight reduction and ensuring toughness and rigidity, still have room for improvement in weight reduction efforts.
Innovation Solution
The exterior cover is designed with an integral layered resin portion comprising a first resin layer with a crystalline structure and a second resin layer with a lower Young's modulus, where the first resin layer is thinner and the second resin layer is thicker, both made of polypropylene or polyamide, to enhance rigidity and toughness while reducing weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the exterior cover is increased to ensure rigidity, then the rigidity is improved, but the weight and material cost are increased
Solution Approach 1:
The exterior cover uses a composite structure with a resin base layer and a foam material layer. The foam material provides rigidity enhancement while being lighter than solid resin, thus improving rigidity without proportionally increasing weight. This composite approach allows weight optimization while meeting rigidity requirements.
Solution Approach 2:
Instead of uniformly increasing the thickness of the entire exterior cover, the invention locally adds foam material at specific positions where rigidity enhancement is needed. This selective reinforcement approach improves rigidity at critical areas while minimizing overall weight increase.
2Strength
If one or more reinforcing ribs are provided on a reverse surface of the exterior cover, then the rigidity is improved, but the shape becomes complicated and weight is increased
Solution Approach 1:
The invention uses a foam material layer with varying density or structure to provide rigidity enhancement without adding complex geometric features like reinforcing ribs. The foam material's inherent cellular structure provides stiffness while maintaining a simple outer shape.
Solution Approach 2:
Instead of changing the geometric shape by adding ribs, the invention changes the material parameters by incorporating foam material with different density, elasticity, or structural properties. This achieves rigidity enhancement through material property modification rather than geometric complexity.
Data Source
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AI summary
An object is to provide an exterior cover for a straddled vehicle which enables promotion of further weight reduction while ensuring rigidity and toughness. An exterior cover 50 for a straddled vehicle includes an integral layered resin portion 63 where: a first resin layer 62 and a second resin layer 61 are layered on and integrally molded with each other; and the first resin layer 62 made of resin with a crystalline structure is thinner than the second resin layer 61 made of a resin having a Young's modulus lower than that of the first resin layer 62. In a first cross-section of the exterior cover cut in a first direction crossing an exterior surface of the exterior cover 50, the integral layered resin portion 63 formed of the first resin layer 62 and the second resin layer 61 which are integrally molded into the layered structure forms: a cover main body 51 U (or 51 D) on which the exterior surface is formed; and two first bending portions 54U (or 54D) respectively formed into bent shapes at both end portions of the cover main body 51 U (or 51 D).