Annular Gearbox Layout for Direct Ratio Selection in Vehicles
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Solution Overview
Problem
Existing gearbox systems for human-powered vehicles, such as bicycles, face issues like high friction, noise, wear, and maintenance due to non-coplanar drive chain links, limited gear ratio changes, and difficulties in retrofitting and integrating with pedal-assisted motors.
Innovation Solution
A gearbox design featuring an annular support with pairs of coaxial and angularly coupled gears, allowing for selective angular movement to change transmission ratios, integrated with a mechanical connection and epicyclic gearing for efficient power transmission and easy retrofitting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If derailleur gear devices are used with pinions on distinct planes, then gear ratio changes are possible, but the drive chain links are not coplanar causing high friction, noise, wear, and loss of transmission performance
Solution Approach 1:
The patent transitions from a traditional derailleur system with pinions on distinct planes to a planar gearbox where all gear elements operate within the same plane. This dimensional reorganization eliminates the non-coplanar drive chain arrangement, resolving the contradiction by maintaining gear ratio variability through planar gear mechanisms while ensuring coplanar chain links for reduced friction and improved reliability
2Adaptability or versatility
If derailleur gear devices are used, then multiple gear ratios are available, but rapid and direct changes between non-consecutive gear ratios are impossible
Solution Approach 1:
The patent employs a dynamic selection mechanism where a movable component can directly engage different gear ratios by shifting position within the planar gearbox structure. This dynamic arrangement enables rapid switching between any gear ratios without the sequential constraints of derailleur systems, as the selection mechanism can directly access any gear pair through linear or rotational movement within the same plane
3Adaptability or versatility
If hub-integrated gearboxes with toothed wheels arranged along their axis are used, then gear ratio changes are possible, but the devices have an elongated shape and occupy significant axial space
Solution Approach 1:
The patent reorganizes the gear arrangement from an axial configuration (toothed wheels stacked along the axis) to a planar configuration (gears arranged within the same plane). This dimensional transformation collapses the axial footprint while maintaining gear ratio functionality, as the planar arrangement allows multiple gear pairs to coexist in a compact radial and axial envelope
4Adaptability or versatility
If wheel hub-integrated gearboxes are used, then gear ratio changes are possible, but retrofitting requires wheel replacement or modification which is difficult and costly
Solution Approach 1:
The patent segments the gearbox into a modular planar unit that can be independently installed within the wheel hub without replacing the entire wheel assembly. This segmentation allows the gearbox to be fitted as a discrete component, enabling straightforward retrofitting of existing vehicles by installing only the gearbox module rather than requiring wheel replacement or frame modification
5Adaptability or versatility
If hub-integrated gearboxes are used, then gear ratio changes are possible, but the entire weight is placed on the rear wheel reducing vehicle dynamic balance
Solution Approach 1:
The patent designs the planar gearbox with a compact structure that can be integrated into the wheel hub while maintaining balanced weight distribution. The universal design allows the gearbox to function effectively regardless of its precise placement within the hub, and the planar configuration enables optimal positioning that minimizes adverse effects on vehicle dynamics and weight balance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces input torque requirements, minimizes mechanical stresses, and enables compact, efficient drive systems that can be easily integrated into existing vehicles, improving performance, reducing maintenance, and facilitating the integration of pedal-assisted motors.
Implementation Method 1
a first gear wheel (53) adapted to mesh with a second gear wheel (55)
Implementation Method 2
The annular support is angularly movable around a selection axis to selectively bring one of said pairs of gears into an angular take-off position
Data Source
AI summary
The gearbox (29) comprises an annular support (31), on which pairs of gears (33A-33J) for the input of motion to the gearbox are rotatably supported. Each pair of gears comprises a first gear (35) adapted to receive an input motion, and a second gear (37); the first gear and the second gear being coaxial and angularly coupled to each other to rotate integrally. Each pair of gears defines a transmission ratio different from the transmission ratios defined by the other pairs of gears. The annular support is angularly movable around a selection axis to selectively bring one of said pairs of gears into an angular take-off position of the motion in input to the transmission ratio gearbox. The gearbox further comprises a mechanical connection between the second gear of the pair of gears which is in the angular take-off position of the motion in input to the transmission ratio gearbox, and an output shaft (45) having an axis of rotation (A-A) parallel to the selection axis or coincident therewith, wherein the output shaft passes inside the annular support.