Motorcycle Rear Suspension Eccentric Layout for Maintenance and Weight Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current motorcycle rear suspension designs face challenges in maintenance accessibility, weight reduction, and compactness due to structural obstructions and increased rigidity requirements, which hinder efficient load transmission and aesthetics.
Innovation Solution
A vehicle body structure with a swing arm and rear suspension positioned eccentrically to the vehicle width center, utilizing a unique frame layout that includes a front frame, main frame members, and rear frame members with assist frame members to create a compact layout space for the rear suspension, allowing direct load transmission and reducing weight by minimizing torsional moments on the cross member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the rear suspension is arranged near the center of the vehicle width, then the structural symmetry is maintained, but maintenance becomes difficult and the suspension cannot be utilized as a mechanical appearance element
Solution Approach 1:
The patent applies asymmetry by arranging the rear suspension on one side of the vehicle rather than at the center. Specifically, the rear suspension is positioned between the left main frame member and left rear frame member, creating an asymmetric layout that provides maintenance accessibility while maintaining structural functionality. This asymmetric arrangement allows the suspension to be exposed and accessible from the side of the vehicle.
2Strength
If the rear suspension is coupled to the cross member, then the load transmission path is established, but the cross member receives bending load and torsional moment requiring high rigidity and increasing weight
Solution Approach 1:
The patent extracts the rear suspension coupling from the cross member and relocates it to the main frame member. The rear suspension is now coupled to the left main frame member at a position below the left rear frame member, separating the suspension mounting function from the cross member. This extraction eliminates the bending load and torsional moment on the cross member, allowing it to be lighter while maintaining load transmission capability through the main frame member.
Solution Approach 2:
The patent changes the coupling position from a lateral arrangement (on the cross member) to a longitudinal arrangement (on the main frame member below the rear frame member). This dimensional change in positioning allows the load to be transmitted along the length of the main frame member rather than creating bending moments on the cross member, reducing the rigidity requirements and weight of the cross member.
3Volume of moving object
If the rear suspension is arranged in the side of the engine within the vehicle body frame, then a compact structure is achieved, but the suspension protrudes laterally forming obstacles and is affected by engine heat
Solution Approach 1:
The patent segments the frame into distinct functional zones: the engine is housed within the vehicle body frame, while the rear suspension is positioned in the space between the main frame member and rear frame member. This segmentation separates the engine and suspension into different spatial zones, allowing the suspension to be compactly arranged without protruding laterally while avoiding direct exposure to engine heat.
4Strength
If the rigidity of the swing arm is increased to handle laterally biased load, then the load bearing capacity is improved, but the weight is widely increased and maintenance becomes difficult
Solution Approach 1:
The patent applies local quality by providing lateral support specifically at the swing arm coupling position rather than increasing the overall rigidity of the entire swing arm. The support structure provides localized reinforcement at the coupling point to handle the laterally biased load, allowing the rest of the swing arm to maintain its original lighter construction while still achieving the required load bearing capacity.
Data Source
AI summary
Disclosed is a vehicle body structure of a motorcycle which intends to make maintenance of a rear suspension easy and arranges the rear suspension in a compact manner. The vehicle body structure includes a vehicle body frame, a swing arm, and a rear suspension interposed between the vehicle body frame and the swing arm. The vehicle body frame includes a front frame body having right and left main frame members, and a rear frame body having right and left rear frame members extending to a rear side from rear end portions of the main frame members. The rear suspension is arranged so as to be eccentric to a right direction of the vehicle body from a center of the vehicle width. The rear frame body has a layout space for the rear suspension in a lower side of the right rear frame member.