Variable Speed Drive With Adjustable Axes for Compact E-Bike Assist
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Solution Overview
Problem
Existing assisted-pedal human-powered vehicles require complex and cumbersome drive systems that are costly and large in size, limiting their adoption due to increased fuel costs and environmental concerns.
Innovation Solution
A variable speed drive system that adjusts the transmission ratio by varying the distance between rotation axes, using a supporting frame that moves or pivots to change the angular position of a ring and coaxial disks, allowing continuous modification of the transmission ratio between a drive member and a driven member, integrated with an electric motor and mechanical transmissions for efficient power combination with user muscle power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional electric motor unit with bottom bracket and pedals is used for assisted-pedal vehicles, then the vehicle can combine human propulsion with electric propulsion, but the drive system becomes complex and cumbersome
Solution Approach 1:
The patent merges the electric motor unit, bottom bracket, and pedal mechanism into a single integrated drive system. The motor (130) is directly coupled to the bottom bracket assembly, with the pedal cranks (103) and chainring (104) forming a unified structure that combines human-powered and electric-powered propulsion through shared mechanical components.
Solution Approach 2:
The bottom bracket assembly serves multiple functions simultaneously: it acts as the motor mounting interface, the pedal crank support, the chainring attachment point, and the chain drive mechanism. This multi-functional design eliminates the need for separate components for each function, reducing overall system complexity.
2Power
If conventional drive systems are used in assisted-pedal vehicles, then the vehicles can provide electric assistance, but the cost and size increase
Solution Approach 1:
The patent combines the motor, transmission, and drive mechanisms into a single bottom bracket assembly, eliminating the need for separate weight-bearing components. The motor (130) is integrated directly into the bottom bracket structure, sharing mechanical components with the human-powered drive system, thereby reducing total weight.
Solution Approach 2:
The motor (130) is positioned within the bottom bracket assembly structure, with its output shaft aligned with the bottom bracket axis. The motor housing and mounting brackets are nested within the existing bottom bracket framework, optimizing space utilization and minimizing additional weight.
3Power
If conventional drive systems are used in assisted-pedal vehicles, then the vehicles can provide electric assistance, but the cost and size increase
Solution Approach 1:
The patent merges the electric motor unit with the bottom bracket and pedal mechanism into a single compact assembly. The motor (130), bottom bracket, pedals, and chainring share common mounting points and structural elements, significantly reducing the overall volume required for the drive system compared to conventional separate-component designs.
Solution Approach 2:
The motor (130) is nested within the bottom bracket assembly, with its housing and mounting structure integrated into the existing framework. The motor shaft aligns with the bottom bracket axis, allowing the motor to occupy space within the existing mechanical envelope rather than adding external volume.
Data Source
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AI summary
A variable speed drive (37) is described, comprising: a ring (60) adapted to rotate about a first rotation axis; two coaxial disks (73), rigidly connected to each other, adapted to rotate about a second rotation axis (B-B) parallel to the first rotation axis; wherein the ring (60) is at least partially housed between the two coaxial disks (73); a plurality of driving members (75), carried by the ring (60) and arranged according to a circular arrangement coaxial to the ring (60); said driving members are arranged and configured to cooperate with opposite surfaces (73A) of the two coaxial disks (73), transmitting a rotation motion from the ring (60) to the two coaxial disks (73); a device for adjusting the distance between the first rotation axis and the second rotation axis. A drive device (17) of an assisted-pedal human-powered vehicle (10) which includes such a drive is also described.