Vehicle Gear Arrangement With Central Machine Gear for Shift-Under-Load
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Solution Overview
Problem
Existing gear arrangements for vehicles driven by muscular force, such as bicycles, face challenges with weight distribution and efficiency due to the integration of electric auxiliary motors, particularly in hub motors, which increase unsprung masses and limit the use of derailleurs due to space constraints and chain movement limitations.
Innovation Solution
A gear arrangement with a machine gear connected between two part-gear mechanisms, allowing torque from both muscular force and an electric machine to be efficiently guided, enabling shifting operations synchronized with the electric drive torque, and incorporating a shifting apparatus with an electric shifting motor for coordinated shifting under load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If hub motors are used in combination with hub gears, then electric auxiliary drive is provided, but the structural space required leads to high weight and unfavorable weight distribution with increased unsprung masses
Solution Approach 1:
The patent extracts the electric machine from the hub motor configuration and relocates it to the central drive unit at the bottom bracket. This separation allows the hub gear to function purely as a transmission mechanism while the electric motor is positioned where it can be better integrated with the frame and weight distribution can be optimized.
Solution Approach 2:
The patent introduces a machine gear as an intermediary component that couples the electric machine to the gear arrangement. This machine gear acts as a mediator between the electric drive and the mechanical transmission system, enabling flexible torque introduction at different locations within the gear mechanism rather than requiring direct hub motor integration.
2Force
If hub motors with high torque are used, then auxiliary drive capability is provided, but the motors are relatively large and have high weight
Solution Approach 1:
The patent merges the electric machine with the central gear mechanism at the bottom bracket, combining the drive function with the existing mechanical transmission structure. This integration allows the electric motor to share space with the gear components and eliminates the need for separate hub motor assemblies.
Solution Approach 2:
The central drive unit serves multiple functions: it houses the electric machine, contains the gear arrangement with multiple gear stages, provides shifting mechanisms, and acts as the primary weight bearing structure. This multi-functionality consolidates what would otherwise require separate components including hub motors.
3Adaptability or versatility
If derailleurs are used with hub motors, then gear shifting is provided, but chain movement is limited due to space constraints
Solution Approach 1:
The patent segments the gear shifting function into two independent parts: the first gear wheel sets handle the primary gear changes, while the second gear wheel sets provide additional gear stage selection. This segmentation allows each shifting mechanism to operate independently with adequate space, eliminating the space constraints that limit derailleurs.
Solution Approach 2:
The patent transitions from the lateral chain movement of derailleurs to axial gear selection within the hub gear mechanism. The second gear wheel sets are arranged to provide gear stage changes in a different dimensional space, allowing multiple gear changes without requiring lateral chain displacement.
4Weight of moving object
If electric machines are integrated centrally at the bottom bracket, then weight distribution is improved, but the chain cannot be moved from one sprocket to another
Solution Approach 1:
The patent replaces the traditional derailleur-based chain shifting mechanism with a hub gear mechanism where gear changes occur through rotational selection of different gear wheel sets. This substitution eliminates the need for lateral chain movement while maintaining centralized drive unit integration.
Solution Approach 2:
The patent implements dynamic gear selection where the gear ratio can be changed on-the-fly by rotating the appropriate gear wheel sets to different angular positions. This dynamic adjustment mechanism allows continuous gear changes without interrupting chain tension or requiring manual pedal force interruptions.
Data Source
AI summary
Gear arrangement for a vehicle, having an input shaft, a layshaft, an output shaft connected to a drive wheel of the vehicle, a plurality of shiftable first gear wheel sets which connect the input shaft and the layshaft and which are each associated with at least one gear stage, and a machine gear connected to one of the shafts and into which the drive torque of an electric machine can be introduced. The first gear wheel sets form a first part-gear mechanism, wherein at least one second shiftable gear wheel set connects the layshaft and the output shaft and forms a second part-gear mechanism, wherein the at least one second gear wheel set is associated with at least one gear stage and wherein the machine gear is arranged in an axial direction between the first part-gear mechanism and the second part-gear mechanism.