Modular Bicycle Derailleur With Coaxial Rear-Axle Mounting
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Solution Overview
Problem
Conventional bicycle derailleurs suffer from positioning inaccuracies due to radial and axial misalignments caused by derailleur hangers, leading to increased tolerance variations, damage susceptibility, and higher leverage forces, especially with larger cassette gears, complicating installation and adjustment, and contributing to resource inefficiency.
Innovation Solution
A bicycle derailleur with a rigid base element and modular design, featuring interchangeable modules such as the base element, pivoting assembly, and chain guide device, allowing for direct coaxial mounting to the rear axle, enabling precise alignment and easy repair or replacement of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If derailleur hangers are used to mount the derailleur, then the derailleur can be replaced without replacing the frame, but positioning inaccuracies and tolerance variations occur
Solution Approach 1:
The base element is divided into multiple modular components (mounting portion, linkage portion, cage portion) that can be independently replaced. This segmentation allows the derailleur to be repaired without replacing the entire assembly, while each module maintains precise manufacturing tolerances for accurate positioning.
Solution Approach 2:
The mounting portion acts as an intermediary component between the frame and the chain guide device. It provides a standardized interface that ensures accurate positioning and alignment, eliminating the tolerance accumulation that occurs with traditional derailleur hangers while still allowing the derailleur to be replaced independently.
2Ease of operation
If traditional derailleur hangers are used, then installation is flexible, but leverage forces increase and damage susceptibility increases
Solution Approach 1:
The mounting portion and linkage portion are merged into a single integrated base element that directly connects to the frame. This eliminates the separate derailleur hanger component, reducing the number of potential failure points and lowering leverage forces while maintaining installation flexibility through the modular design.
Solution Approach 2:
The base element is pre-configured with optimized geometry and material properties to withstand leverage forces before assembly. The integrated design incorporates reinforcement features and stress distribution pathways that prevent damage initiation, allowing the derailleur to be installed flexibly while resisting damage.
3Loss of substance
If modular design with interchangeable modules is implemented, then resource consumption decreases, but device complexity increases
Solution Approach 1:
The derailleur is segmented into three main modules (mounting portion, linkage portion, cage portion) that can be independently manufactured, repaired, and replaced. This segmentation reduces resource consumption by allowing selective replacement of only the damaged module rather than the entire derailleur, while the standardized interfaces minimize the complexity of assembly.
Solution Approach 2:
The base element serves multiple functions: it provides mounting to the frame, houses the linkage mechanism, and supports the chain guide device. This multi-functionality reduces the total number of components needed, decreasing resource consumption while the modular architecture manages the complexity through functional integration.
Data Source
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AI summary
The invention relates to two aspects of a motor-gearbox unit (AG) for an electric bicycle derailleur (RD) with a base element (KB). These aspects are functionally complementary and work together to ensure a low-tolerance and backlash-free mounting of the motor-gearbox unit and its battery unit (UB). The first aspect relates to a motor-gearbox unit with a housing (SH1, SH2). The housing, with respect to its six degrees of spatial freedom, can be connected to the base element via exactly one rotary axis connection (CR) and two translational stop connections (CT1, CT2). This defines the position of the motor-gearbox unit within the base element without causing any geometric or tolerance-related under- or over-constraints. The second aspect relates to a motor-gearbox unit with a locking mechanism for mounting a battery unit.A locking lever (LL) of the locking assembly can be pivotally mounted on the base element with longitudinal play (AL, HO). An elastic clamping force (FE) generated by the locking lever acts along a closed force path through the battery unit and the housing. The base element is explicitly not part of the force path in order to achieve a minimized tolerance chain.