Folding Bicycle Assembly with Skewed Hinge Axes
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Solution Overview
Problem
Conventional folding bicycles are cumbersome and difficult to store or transport due to their size, often compromising stability and comfort, and existing designs face issues with hinge durability and folding complexity.
Innovation Solution
A folding bicycle design with two frame hinges that fold along vertical and parallel planes, allowing for a compact configuration with improved stability and ease of use, featuring skewed hinge axes to avoid interference and enable rolling in the folded state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a single hinge joint is used on the frame, then the bicycle length is reduced by about half, but the folded bicycle remains too large and cumbersome to carry or store
Solution Approach 1:
The frame is divided into multiple segments connected by two hinge joints: a first hinge joint connecting the head tube to the main frame and a second hinge joint connecting the main frame to the rear triangle. This segmentation allows the bicycle to be folded into a compact configuration where the front assembly and rear assembly can be positioned close together, reducing overall length and improving portability.
2Length of moving object
If a second hinge is added to reduce length, then the folded length is reduced to approximately one-third, but the hinge requires strong clamping means to resist bending stress
Solution Approach 1:
The clamping function is extracted from the hinge joint itself and transferred to separate clamp members that engage with the frame tubes. The hinge joint becomes a simpler pivoting connection, while the clamping function is performed by dedicated clamp members with ratchet mechanisms that can be independently adjusted and secured.
Solution Approach 2:
Clamp members act as intermediary elements between the hinge joint and the frame tubes. These clamps provide the necessary clamping force and resistance to bending stress without requiring the hinge joint itself to be overly complex. The clamps serve as mediators that transfer and distribute mechanical loads.
3Device complexity
If the first hinge axis is oriented vertically, then the folding mechanism is simplified, but natural forces during riding put bending stress on the main frame hinge
Solution Approach 1:
The first hinge axis is oriented asymmetrically at an angle to the vertical plane, specifically positioned to receive the second hinge axis. This asymmetric orientation allows the hinge mechanism to remain relatively simple while distributing bending stresses more effectively through the frame structure, improving durability without requiring complex reinforcement.
4Shape
If the second hinge axis is oriented laterally parallel to the wheel axle, then the folding geometry is defined, but the folded bicycle cannot be rolled on the ground without special rollers
Solution Approach 1:
The second hinge axis is oriented laterally in a direction parallel to the wheel axle, creating a folded configuration where the bicycle can be positioned for rolling. This lateral orientation, combined with the first hinge's angular orientation, enables the bicycle to be rolled on its front wheel in the folded state, improving transportability without requiring special rollers.
Data Source
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AI summary
In reference to FIG. 4, a folding bicycle with a plurality of hinges and quick-release clamps. A folding bicycle can easily be changed between a riding position and a folded position for storage and transportation. The folding bicycle comprises a rear wheel assembly (1), a central frame assembly (6), a steering assembly (13), a seat assembly (18), a plurality of hinge couplings, and a plurality of quick-release clamps. A plurality of hinge couplings are used to allow the bike to fold in thirds, while the quick-release clamps allow various parts to easily be moved when desired, such as sliding the seat assembly down or detaching the rear wheel assembly (1) from the central frame assembly (6). In a riding position the folding bicycle functions as a normal bicycle. The folding bicycle can be converted to a folded position by using the hinge couplings and quick-release clamps to fold the rear wheel assembly and the steering assembly adjacent to the central frame assembly, fold part of the steering assembly down, and sliding the seat assembly down into the central frame assembly.