Battery Pack Positioning Between Sprockets for Bicycle Stability
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Solution Overview
Problem
Motorized bicycles with high-positioned battery packs experience stability issues and are difficult to handle due to increased center-of-gravity, and after-market conversions often require significant frame modifications and cannot be easily carried or recharged like ordinary bicycles.
Innovation Solution
Positioning the battery pack low between the first and second sprockets within the loop of the endless chain or belt, with a support system that allows for easy mounting and removal, and integrating a rotation sensor and control unit to minimize balance disruption and facilitate handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the battery pack is positioned high (between the seat tube and rear wheel or between the luggage carrier and rear wheel), then the electrical energy storage capacity is sufficient, but the center of gravity increases resulting in reduced stability and harder handling
Solution Approach 1:
The battery pack is repositioned from traditional high locations (between seat tube-rear wheel or luggage carrier-rear wheel) to a low position between the first and second sprockets within the chain loop. This spatial relocation in the vertical dimension lowers the center of gravity while the horizontal positioning within the chain loop maintains adequate energy storage capacity.
Solution Approach 2:
The battery pack is nested within the existing chain loop structure between the sprockets, utilizing the available space in the drivetrain area. This nesting approach allows the battery to be integrated into the bicycle's existing mechanical structure without adding external protrusions that would raise the center of gravity.
2Adaptability or versatility
If after-market conversion battery packs are mounted on the frame or luggage carrier, then the bicycle can be converted to motorized, but the center of gravity shifts upward and the bicycle cannot be handled or carried as an ordinary bicycle
Solution Approach 1:
The battery pack positioning system is designed to be universal, working with both ordinary bicycles and motorized conversions. The low-position mounting between sprockets is compatible with standard bicycle frames, allowing the bicycle to maintain its ordinary handling characteristics and portability while enabling motorized conversion capability.
Solution Approach 2:
Instead of mounting the battery pack on external structures (luggage carrier or frame) that raise the center of gravity, the invention inverts the approach by integrating the battery into the low-position drivetrain area between sprockets. This inversion of mounting location restores ordinary bicycle handling while providing motorized conversion capability.
3Ease of operation
If the battery pack is positioned low between the first and second sprockets within the chain loop, then the center of gravity is reduced improving stability, but the space availability is limited
Solution Approach 1:
The battery pack is positioned at a specific local area between the first and second sprockets within the chain loop, utilizing the three-dimensional space in this localized region. This local positioning provides sufficient volume for battery installation while maintaining the low center of gravity for improved stability.
Data Source
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AI summary
A drive unit (20) for a motorised bicycle (10) adapted to be at least partly powered by an electrical motor (18) is disclosed. The drive unit (20) comprises: a battery pack (84) including one or more battery cells (22) for providing the electrical motor with electrical energy, and a battery pack support (70, 72) for connecting the battery pack to the frame (12), where the battery pack support and the battery pack are adapted for positioning a battery cell of the one or more battery cells between the first (64) and second (66) sprockets of the motorised bicycle.