Bicycle Electric Drive Planetary Gear Common Axis Mounting
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Solution Overview
Problem
Existing electric drive devices for bicycles, particularly those using planetary gear sets, face challenges in achieving a compact and cost-effective design while maintaining reliable noise reduction and efficient drive transmission.
Innovation Solution
The electric drive device incorporates a planetary gear set where the sun gear, planet gears, and internal gear are rotatably mounted about a common axis, utilizing a fixed axle pin for mounting, which simplifies and compacts the design, allowing for effective drive power transmission and reduced noise through specific bearing arrangements and integral gear configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the sun gear, planet gears, and internal gear are mounted on separate axes, then the planetary gear set can be structurally stable, but the drive device becomes larger and less compact
Solution Approach 1:
The patent merges multiple mounting axes into a single common axis by providing a common bearing arrangement that supports the sun gear, planet gears, and internal gear all rotating about the same axis. This consolidation reduces the overall volume of the planetary gear set while maintaining structural stability through the integrated bearing support system.
Solution Approach 2:
The common bearing arrangement serves multiple functions simultaneously: it supports the sun gear rotation, supports planet gear rotation, and supports internal gear rotation, all about a single common axis. This multi-functional bearing system reduces the number of separate mounting components needed, achieving compactness without excessive structural complexity.
2Ease of manufacture
If conventional planetary gear sets are used, then reliable drive transmission is achieved, but manufacturing costs increase and compactness is reduced
Solution Approach 1:
The patent segments the planetary gear set into modular components (sun gear, planet gears, internal gear) that all share a common mounting axis and bearing arrangement. This segmentation allows each component to be manufactured separately using standard processes, reducing overall manufacturing cost while maintaining reliable drive transmission through precise modular assembly.
Solution Approach 2:
The patent changes the geometric parameter of the mounting arrangement from separate axes to a common axis configuration. This parameter change simplifies the overall structure, reduces manufacturing complexity and cost, while maintaining the fundamental meshing relationships that ensure reliable drive transmission between gear components.
3Object-generated harmful factors
If materials optimized for noise reduction are used, then noise development is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
The patent employs bearing arrangements that inherently provide noise reduction through their design and material selection, without requiring additional noise-control components or complex manufacturing processes. The bearings themselves serve the dual function of supporting rotation and reducing noise generation from gear meshing, achieving noise control through the basic support structure rather than added complexity.
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
This configuration results in a more compact, cost-effective, and reliable drive device with improved noise reduction and efficient drive transmission to the bicycle's traction mechanism, enhancing the overall performance and manufacturing efficiency.
Implementation Method 1
The planetary gear set comprises a sun gear, which is drive-connected with the motor shaft, at least two planet gears which are in engagement with the sun gear and an internal gear that is in engagement with the planet gears
Implementation Method 2
utilizing a fixed axle pin for mounting, which simplifies and compacts the design, allowing for effective drive power transmission and reduced noise through specific bearing arrangements
Data Source
AI summary
The present invention relates to a drive device (1) for the assisted driving of a bicycle (2), which comprises an electric motor (3) and a driven shaft (6) that can be coupled to a traction mechanism drive (7) of the bicycle (2), wherein a planetary gear set (10) of the drive device (1) drive-connects a motor shaft (4) of the electric motor (3) with the driven shaft (6). A compact and cost-effective construction as well as an improved drive transmission of the drive device (1) materialise in that at least one sun gear (11), one internal gear (15) and one planet gear carrier (16) of the planetary gear set (10) are rotatably mounted about a common axis of rotation (17) in the planetary gear set (10).Further, the invention relates to a bicycle (2) having such a drive device (1).