Motorcycle Rear Fender Segmentation for Mud Guarding and Weight Reduction
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Solution Overview
Problem
Conventional motorcycles with movable rear fenders face challenges in achieving high mud guarding performance and rigidity while minimizing unsprung weight, as increasing fender size or rigidity often leads to noise and weight-related issues.
Innovation Solution
A motorcycle design featuring a rear fender with plastic left and right side guards and a fender main body, where the side guards are connected to the fender main body in a configuration that enhances mud protection and reduces vibration, and the use of openings to reduce weight and noise, while maintaining sufficient rigidity through C-shaped cross-sectional shapes and separate part assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the left and right side face portions of the movable rear fender are made large in area to improve mud guarding performance, then the mud guarding performance is improved, but the side face portions tend to bend easily and vibrate causing noise
Solution Approach 1:
The rear fender is divided into multiple separate components: the fender main body and the left/right side face portions. These segments are connected via connection portions rather than being integrally formed, allowing each part to be optimized independently. The side face portions can be made smaller and more rigid while still providing adequate mud protection when positioned correctly.
Solution Approach 2:
The connection portions extend in the vehicle width direction (lateral dimension) to connect the side face portions to the fender main body. This dimensional approach creates a stable triangular support structure that prevents bending and vibration of the side face portions without requiring them to be large in area.
2Strength
If high-rigidity metallic material is used to increase the rigidity of the movable rear fender, then the rigidity is improved, but the weight of the movable rear fender increases, leading to increased unsprung weight and poor riding comfort
Solution Approach 1:
The rear fender employs a composite structure where the fender main body and side face portions are made from lightweight materials such as plastic or thin metal sheets, rather than solid metallic materials. This composite approach maintains sufficient rigidity through the segmented design and connection portions while dramatically reducing the overall weight and unsprung mass.
Solution Approach 2:
By segmenting the fender into separate parts connected by connection portions, the design achieves rigidity through structural arrangement rather than material density. This allows the use of lightweight materials that would otherwise be too flexible, solving the contradiction between rigidity and weight.
3Object-generated harmful factors
If holes are formed in the left side face portion or right side face portion to prevent noise, then the noise is reduced, but the rigidity of the side face portion decreases
Solution Approach 1:
Rather than forming holes in large side face portions, the design segments the fender into separate components. The side face portions are kept small and rigid, connected to the main body through connection portions. This segmentation eliminates the need for holes to reduce noise, as the small size and connection structure inherently prevent vibration and noise generation.
Data Source
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AI summary
A motorcycle (1) comprising a rear fender (30) including a fender main body (31) disposed above a rear wheel (22), a left side guard (40) disposed to the left of the rear wheel (22), and a right side guard disposed to the right of the rear wheel (22), wherein a first left opening (47) is defined by the fender main body (31), a left side guard body portion (43), and a first left arm portion (41), as viewed from the left side of the motorcycle and a first right opening is defined by the fender main body (31), a right side guard body portion, and a first right arm portion, as viewed from the right side of the motorcycle.