Freewheel Cage Roller Retention for Easier E-Bike Assembly
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Solution Overview
Problem
Existing cage freewheels for shaft/hub connections, particularly in e-bike drives, face challenges with complex assembly and installation due to bearing rollers easily falling out and axial misalignment, leading to potential malfunctions.
Innovation Solution
The bearing rollers are positively accommodated in radial pockets within the freewheel cage, secured by elastic deformation of a plastic cage, allowing easy assembly and installation by clipping them into place, while the sprags are held by an annular spring, preventing axial misalignment and ensuring secure fit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bearing rollers are arranged in pairs on both sides of the annular spring in a conventional cage freewheel, then the shaft and hub can be supported relative to each other, but the bearing rollers can easily fall out during installation and the axial position is not fixed
Solution Approach 1:
The cage is divided into multiple pockets, with each pocket containing a bearing roller. The pockets are separated by webs, creating discrete compartments that secure the rollers in place while allowing the annular spring to function independently in the engagement direction.
Solution Approach 2:
The bearing rollers are nested within the pockets of the cage structure. The cage acts as a container that holds the rollers securely, preventing them from falling out during installation while maintaining their support function. The annular spring is nested within the same cage structure but operates independently.
2Length of stationary object
If the cage freewheel is designed with bearing rollers integrated into the cage, then the axial dimension can be reduced, but the assembly and installation become complex and difficult
Solution Approach 1:
The cage is segmented into multiple pockets separated by webs, with each pocket designed to hold a bearing roller. This segmentation allows for simplified assembly where components can be installed in a systematic manner rather than requiring complex positioning procedures.
Solution Approach 2:
The annular spring acts as an intermediary element that mediates between the bearing rollers and the engagement mechanism. It provides the necessary force to engage the sprags while allowing the bearing rollers to remain in their pockets, simplifying the overall assembly process.
3Device complexity
If bearing rollers are held in place without positive accommodation, then the cage structure can be simpler, but the rollers can fall out and become lost during assembly
Solution Approach 1:
The cage is divided into discrete pockets separated by webs, creating individual compartments for each bearing roller. This segmentation provides positive accommodation for the rollers, ensuring they remain in place during assembly and operation while maintaining a relatively simple overall cage structure.
Solution Approach 2:
The retention function is extracted from the overall cage structure and implemented through the pocket design. The pockets provide the necessary constraint for the bearing rollers without requiring additional complex retention mechanisms, separating the retention function from the structural support function.
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 design simplifies assembly and installation, reduces the risk of parts falling out, and enhances the functionality and reliability of the freewheel by maintaining proper alignment and force transmission.
Implementation Method 1
the bearing rollers are clipped into their pockets by elastic deformation of the cage
Implementation Method 2
An annular spring, which runs in a slot in the radially outer surface of the sprags around the row of sprags, ensures that the sprags are spring-loaded in the engagement direction
Implementation Method 3
The sprags are pivotally arranged so that they frictionally lock relative movement between the shaft and hub in one direction of rotation and release it in the other
Implementation Method 4
The bearing rollers serve to support the shaft and hub relative to each other
Data Source
Figure 1
Figure 2~3
AI summary
In a cage freewheel for installation in the clamping gap of a shaft/hub connection, particularly in the drive of an e-bike, with an annular cage which is equipped in circumferential direction with both bearing rollers for supporting the hub and shaft against each other, and with clamping elements pivotably arranged in the cage, wherein the clamping elements frictionally lock a relative movement between the shaft and hub in one direction of rotation, release it in the other and are spring-loaded in the engagement direction by a ring spring running around the row of clamping elements in a slot in the radially outer surface of the clamping elements, and the bearing rollers are arranged in pairs in associated pockets of the cage on both sides of the ring spring, it is provided that the bearing rollers are positively engaged in the associated pockets.