Compact Folding Bicycle Dual-Hinge Mechanism
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Solution Overview
Problem
Conventional folding bicycles have a large footprint in their folded configuration due to a single hinge design, which limits their ability to be conveniently transported on buses and trains, and existing dual-hinge designs face issues with bending stress and lengthy folding/unfolding times.
Innovation Solution
A foldable bicycle design with two hinges that allow the front and rear assemblies to fold along predominantly vertical and parallel longitudinal planes toward a central frame portion, utilizing a main frame pivot axis angled relative to both horizontal and vertical planes to achieve a compact, small-footprint folded arrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single hinge design is used for folding bicycles, then the structure is simple, but the footprint in folded configuration is large
Solution Approach 1:
The bicycle frame is divided into multiple segments (front assembly, main frame, rear assembly) that can be independently folded about different hinge axes. The front assembly folds about a first hinge axis, while the rear assembly folds about a second hinge axis, allowing each segment to be compacted separately to reduce overall footprint.
Solution Approach 2:
The folding mechanism transitions from single-plane folding to multi-dimensional folding by introducing hinge axes at different orientations. The first hinge axis is substantially perpendicular to the second hinge axis, enabling folding in orthogonal dimensions and achieving compact packaging in three-dimensional space.
2Area of stationary object
If dual-hinge design is used to reduce footprint, then the folded size is reduced, but bending stress increases
Solution Approach 1:
The hinge structures are strategically positioned at specific locations on the frame (head tube region and seat tube region) to optimize stress distribution. Each hinge is designed with specific geometric characteristics at its location to minimize bending moments while enabling effective folding motion.
Solution Approach 2:
The two hinge axes are oriented asymmetrically relative to each other and to the frame geometry, with the first hinge axis substantially perpendicular to the second hinge axis. This asymmetric arrangement optimizes the folding path to reduce bending stress on frame members while achieving compact folded dimensions.
3Area of stationary object
If dual-hinge design is used to reduce footprint, then the folded size is reduced, but folding/unfolding time increases
Solution Approach 1:
The hinge structures are pre-configured in the frame design with optimized pivot points and folding paths. The handlebar stem and seat post are positioned to facilitate intuitive folding motion, allowing users to quickly collapse the bicycle without complex manipulation sequences.
Solution Approach 2:
The folding mechanism allows dynamic, continuous motion about the hinge axes rather than requiring discrete steps. The perpendicular arrangement of hinge axes enables smooth transitions between folded and unfolded states, reducing the time required for folding operations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables quick and intuitive folding into a compact volume with a length about one-third of a full-sized bicycle and a width less than the combined width of the wheels, facilitating transport and storage while maintaining conventional riding geometry.
Implementation Method 1
a hinge coupling enabling relative pivoting of the forward and rearward portions about a main frame pivot axis
Implementation Method 2
a rear wheel assembly hinge configured to allow the rear wheel to pivot relative to the main frame member in a vertical plane coincident with the rear vertical longitudinal plane
Data Source
AI summary
A vehicle having a front wheel, a main frame member and a rear wheel assembly including a rear wheel is configured for conversion between expanded and folded arrangements. A hinge coupling enables relative pivoting of forward and rearward portions of the main frame member about a main frame pivot axis extending at an acute angle relative to a rear vertical transverse plane and at an acute angle relative to a horizontal plane. A rear wheel assembly hinge is configured to allow the rear wheel assembly to pivot relative to the main frame member within a vertical plane coincident with the rear vertical longitudinal plane. The front vertical longitudinal plane and the rear vertical longitudinal plane are spaced apart and approximately parallel, in the folded arrangement.