Split Bicycle Transmission Layout for Load-Shifting E-Drives
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Solution Overview
Problem
Existing gear arrangements for human-powered vehicles, such as bicycles, face challenges with weight distribution and unsprung masses when combining hub motors with derailleur gears, and restricted chain shifting due to space constraints, particularly in bottom bracket areas.
Innovation Solution
A transmission arrangement with a machine gear connected between two partial transmissions, allowing muscle power torque to be routed through both partial transmissions while electric machine torque is routed via the second partial transmission, and featuring a switching device coordinated with an electric switching motor to manage gear shifts efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If hub motors are combined with derailleur gears, then drive power is provided, but weight distribution becomes unfavorable and unsprung mass increases
Solution Approach 1:
The patent transitions from radial/axial motor arrangements to a tangential mounting configuration where the electric machine is positioned at the tangent point of the drive wheel. This dimensional change allows the motor to be mounted on the frame rather than integrated into the wheel hub, reducing unsprung mass and improving weight distribution while maintaining drive power delivery through the chain drive system
2Power
If hub motors are used, then drive power is provided, but device size and weight increase
Solution Approach 1:
The patent extracts the electric machine from the wheel hub assembly and relocates it to the frame at the tangent point. This separation removes the heavy motor component from the rotating unsprung mass, significantly reducing device size and weight in the wheel assembly while the motor itself can be compactly mounted on the frame structure
3Adaptability or versatility
If chain shifting is implemented in bottom bracket area, then gear changes are possible, but space constraints restrict movement
Solution Approach 1:
The patent relocates the chain drive and gear shifting mechanism from the constrained bottom bracket area to the tangent point of the drive wheel on the frame. This spatial relocation provides ample room for chain movement and gear shifting operations, eliminating the space constraints of the bottom bracket region while maintaining full gear change functionality
Data Source
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AI summary
A transmission arrangement (16) for a vehicle (F), in particular for a vehicle which can be driven by muscle power, such as a bicycle (F), having an input shaft (50), having a countershaft (30), having an output shaft (36) which is connectable to a drive wheel (20) of the vehicle (F), having a multiplicity of shiftable first gear ratio wheel sets (R1-R4) which connect the input shaft (50) and the countershaft (30) and which are assigned to in each case at least one gear ratio stage, having a machine toothed wheel (40) which is connected or connectable to one of the shafts and into which drive torque (TM) of an electric machine (22) can be introduced. Here, the first gear ratio wheel sets (R1-R4) form a first sub-transmission (32), wherein at least one second shiftable gear ratio wheel set (R5-R7) connects the countershaft (30) and the output shaft (36) and forms a second sub-transmission (34), wherein the at least one second gear ratio wheel set (R5-R7) is assigned to at least one gear ratio stage, and wherein the machine toothed wheel (40) is arranged in an axial direction between the first sub-transmission (32) and the second sub-transmission (34).