Integrated E-Bike Drive Unit for Low Center of Gravity
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Solution Overview
Problem
Off-road electric bicycles, or e-mountain bikes, face challenges in handling and safety due to a high center of gravity, which impairs cornering and increases the risk of rollovers. The weight of batteries and motors affects the bike's balance, and the open down tube construction compromises frame stiffness and weight.
Innovation Solution
The integration of an Electric Bicycle Drive Unit into the Bottom Bracket Area of the bicycle frame, where the Energy Storage Device is positioned adjacent to the motor, reducing the center of gravity and allowing for a more compact and rigid frame design. This configuration includes a Bicycle Frame or Frame Interface Unit with specific mounting axes and a closed tube cross-section for the down tube, enhancing stiffness and reducing weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the battery and motor are positioned in the down tube area, then the center of gravity shifts forward, but handling deteriorates and rollover risk increases
Solution Approach 1:
The battery and motor are merged into a single integrated drive unit positioned in the bottom bracket area, combining the functions of power storage and power delivery in one compact assembly that optimizes center of gravity location for improved handling
2Volume of stationary object
If an open down tube construction is used to accommodate the battery, then installation space is provided, but frame stiffness and weight ratio deteriorate
Solution Approach 1:
The battery and motor are combined into a single integrated unit, eliminating the need for open down tube construction and allowing the down tube to maintain its closed cross-section for optimal stiffness while still providing adequate installation space in the bottom bracket area
Solution Approach 2:
The drive unit is positioned in the bottom bracket area rather than extending into the down tube, changing the spatial arrangement from longitudinal (down tube) to radial (bottom bracket), which preserves frame stiffness while providing necessary installation space
3Volume of stationary object
If the battery is positioned far from the rear wheel axle, then installation space is available, but the center of gravity shifts forward deteriorating handling
Solution Approach 1:
The battery and motor are merged into a compact integrated unit that fits within the bottom bracket area, preventing the battery from being positioned too far forward while still providing adequate installation space through efficient space utilization
4Power
If the electric motor is added to the bottom bracket shaft area, then drive function is provided, but radial clearance for rear wheel tire is reduced
Solution Approach 1:
The motor and battery are merged into a single integrated unit with optimized dimensions that fit within the bottom bracket area, providing the necessary drive function while minimizing the increase in radial clearance requirements through efficient packaging
Data Source
AI summary
The disclosure relates to an electric Bicycle Drive Unit for arrangement in a Bottom Bracket Area of a Bicycle Frame. The Drive Unit has an Electric Motor Device and a Bottom Bracket Assembly having a Bottom Bracket Shaft. The disclosure also relates to a Bicycle Frame or Frame Interface Unit, and an Energy Storage Device for the Electric Bicycle Drive Unit. The Drive Unit includes s an Integrative Energy Storage Device for supplying energy to the motor device. The Integrative Energy Storage Device can be arranged adjacent to the motor device in such a way that the center of gravity position of the Energy Storage Device and the center of gravity position of the Drive Unit lie within the Bottom Bracket Area.