Flip-Pivot Bicycle Frame Folding Mechanism
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Solution Overview
Problem
Existing collapsible bicycle designs are not optimal in terms of compactness and rigidity, particularly for larger wheeled bicycles, as they either result in a non-compact size or require dismounting of the steering wheel, and often lack sufficient mechanical strength without additional weight and cost.
Innovation Solution
A collapsible bicycle foldable about multiple axes, comprising three rigid frame-segments connected via a pivot-axis and a flip-axis, allowing for simpler and more compact folding without removing the front wheel, and equipped with an extra frame-brace for enhanced rigidity, utilizing a unique folding mechanism that relocates wheels to achieve a compact size and maintain ergonomic comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the bicycle is folded in half about an axis perpendicular to the ground, then the folding mechanism is simple, but the compactness is reduced and rigidity is compromised
Solution Approach 1:
The bicycle frame is divided into three rigid segments (steering frame, driving frame, central frame) that can be folded independently about different axes, allowing the rear wheel assembly to be flipped forward while the front wheel remains mounted, achieving compactness without disassembly
Solution Approach 2:
The folding operation transitions from a single-axis fold (perpendicular to ground) to a multi-axis fold where the rear wheel assembly rotates forward along an axis parallel to the ground, changing the folding dimension to achieve better compactness and maintain wheel mounting
2Volume of moving object
If the complete rear wheel assembly is flipped sideways forward along the seatpost axis, then compactness is improved, but the steering wheel must be dismounted and re-mounted
Solution Approach 1:
The frame is segmented into three rigid portions that can be folded independently, allowing the rear wheel assembly to be flipped forward while the front wheel remains mounted on the steering frame segment
Solution Approach 2:
The folding mechanism uses dynamic rotation of the rear wheel assembly forward along an axis parallel to the ground, enabling the wheel to move into a compact position without requiring dismounting and re-mounting operations
3Volume of moving object
If the rear wheel assembly is flipped underways forward along the crankshaft axis, then compactness is improved, but the main frame must run relatively high
Solution Approach 1:
The folding axis is changed from the crankshaft axis (horizontal) to an axis parallel to the ground, allowing the rear wheel assembly to flip forward in a different plane that reduces the required main frame height while maintaining compactness
4Device complexity
If the frame uses a single frame-tube to connect the rear wheel frame and headset, then device complexity is reduced, but rigidity is insufficient
Solution Approach 1:
The frame is divided into three rigid segments connected by pivot joints, creating a modular structure that maintains simplicity while enabling the rear wheel assembly to be flipped forward without requiring additional reinforcement tubes
Solution Approach 2:
The dynamic folding mechanism allows the rear wheel assembly to rotate forward along an axis parallel to the ground, eliminating the need for heavy reinforcement while maintaining structural rigidity through the three-segment frame design
Data Source
AI summary
The flip-pivot bicycle is a collapsible bicycle, that can be folded by a new method, and belongs into the class of the bicycles foldable about two or more axes. The flip-pivot bicycle consists of a driving-frame-segment (1) comprising the driving-wheel (7), a steering-frame-segment (3), comprising the steering-wheel (6), and a central-frame-segment (2), which connects them. The central-frame-segment (2) and the driving-frame-segment (1) is connected by and can pivot above a pivot-axis (4), which pivot-axis (4) is perpendicular to the plane of the parallelly positioned wheels (6, 7), or forms an angle of maximum 45 degree with this perpendicular. The central-frame-segment (2) and the steering-frame-segment (3) is connected and can pivot by a flip-axis (5), which flip-axis (5) is in the plane of the parallelly positioned wheels (6, 7), or is parallel to this plane, or forms an angle of maximum 45 degree with this plane. The function of the flip-axis (5) is to relocate the wheel distant to the pivot-axis (4) as close (or approximately as close) to the pivot-axis (4) as the other wheel is. Thereby flipping the driving-frame-segment (1) on the central-frame-segment (2) by the flip-axis (5), and offset the original planes of the wheels (6, 7) in the meantime, the two wheels (6, 7) can be folded next to each-other. Beyond the above, the flip-pivot bicycle can be equipped with an extra frame-brace; with central-suspension; with crank-anus with releasable fixing which can be re-fixed also in less than 180 degree to each-other, and/or the with pedals inward; with stem that can be slided into one of the forks or next to it; and with seatpost miming out of the plane of the driving wheel.