Scooter Frame Rear Extension for Weight and Footrest Space
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Solution Overview
Problem
Scooter type vehicles with separate lower and seat frames face challenges in achieving a balance between strength, weight, and footrest space, as the need for stronger lower frames results in heavier and larger seat frames, and attempts to reduce size through connecting extensions can compromise footrest space or increase vehicle length.
Innovation Solution
The scooter design features separate lower and seat frames with a rear extension on the lower frame, allowing for reduced seat frame size and weight without compromising footrest space, by positioning the pivot shaft forward and using reinforcement members to enhance connection strength, thus avoiding interference and maintaining a compact vehicle size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If the lower frame and seat frame are formed by separate pipes, then the size and weight of the seat frame can be reduced, but the connection strength between the frames decreases and a larger connecting portion is required
Solution Approach 1:
The lower frame is divided into a main body portion and a rear extension portion that are spatially separated. The rear extension projects rearward from the main body, creating distinct functional zones: the main body for primary structural support and the rear extension for connection purposes. This segmentation allows the seat frame to be optimized independently while maintaining connection strength through the extended lower frame structure.
Solution Approach 2:
The rear extension adds a dimensional element to the lower frame by projecting rearward beyond the main body's rearward extent. This creates additional space in the rearward direction for the connecting portion, allowing the seat frame to connect at a location that does not compromise footboard length. The extension transforms a two-dimensional frame layout into a three-dimensional configuration with extended reach.
2Strength
If the rear end of the lower frame is extended rearward to ensure sufficient connection area, then the connection strength is improved, but the footboard length in the front-rear direction is shortened
Solution Approach 1:
The lower frame is segmented into a main body portion that supports the footboard and a separate rear extension portion that provides the connection area. This segmentation allows the footboard to extend forward from the main body while the rear extension projects rearward from the main body, ensuring that the connection area does not encroach on the footboard's forward length.
Solution Approach 2:
The rear extension utilizes the rearward dimension to create connection space, allowing the footboard to maintain its forward length without compromise. By extending the lower frame rearward from the main body, the design creates a three-dimensional configuration where the footboard and connection portion occupy different spatial zones along the front-rear axis.
3Strength
If the pivot shaft is arranged more rearward to avoid interference with the extended lower frame, then the connection area is sufficient, but the overall vehicle size increases
Solution Approach 1:
The rear extension is designed with specific local characteristics: it projects rearward from the main body but its lower end is positioned forward of its upper end. This creates a localized connection area at the rear extension that is sufficient for the seat frame connection while maintaining a compact overall vehicle profile. The pivot shaft can be positioned to clear this localized extension without requiring excessive rearward placement.
Solution Approach 2:
The rear extension provides more than the minimum required connection area by projecting beyond the main body, but the extension is controlled in its dimensions and positioning. The lower end being forward of the upper end creates a tapered configuration that provides sufficient connection surface area without excessive rearward projection, allowing the pivot shaft to be positioned optimally without increasing overall vehicle length.
Data Source
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AI summary
A body frame 10 of a scooter type vehicle includes a down frame 12 extending downward from a head pipe 11, a lower frame 13 extending rearward from the down frame 12, and a seat frame 14 extending rearward and upward from the lower frame 13. The lower frame 13 and the seat frame 14 are formed as separate parts. The lower frame 13 includes a main connecting portion 131 connected to a lower end surface of the seat frame 14, and a rear extension 135 located rearward relative to the main connecting portion 131. A lower end 135b of a rear edge 135a of the rear extension 135 is located forward relative to an upper end 135t of the rear edge 135a. The rear edge 135a extends rearward and upward.