Cage Freewheel Roller Retention for Easier Shaft-Hub Assembly
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Solution Overview
Problem
Existing cage freewheels face complex and difficult assembly due to loose bearing rollers and lack of axial position fixation, leading to potential malfunction and increased axial structural dimension in shaft/hub connections, particularly in e-bike drives.
Innovation Solution
The cage freewheel features bearing rollers received in a positively locking manner within the annular cage, achieved through elastic deformation of a plastic material, allowing for simplified assembly and secure retention, with projections and pockets ensuring the rollers remain in place without deforming over the entire length, and a configuration that allows for both pre- and post-spring installation clipping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bearing rollers are arranged in pairs on both sides of the annular spring in the cage, then the anti-friction bearing function is integrated into the freewheel, but the assembly becomes complicated and difficult, and the rollers can fall out during assembly
Solution Approach 1:
The cage is divided into multiple pockets, each designed to receive and secure individual bearing rollers. The pockets are separated by webs, allowing independent assembly and securing of each roller without affecting others. This segmentation simplifies the assembly process while maintaining the anti-friction bearing function.
Solution Approach 2:
The bearing rollers are nested within the pockets of the cage structure, with each roller positioned in its own dedicated pocket. The pockets are formed by the cage walls and webs, creating a nested configuration where the rollers are contained within the cage structure. This prevents rollers from falling out during assembly while integrating the bearing function.
2Ease of operation
If the bearing rollers are not axially positioned, then the assembly process is simpler, but the axial position is not fixed, leading to difficult assembly of the annular spring and potential collision of rollers with the spring
Solution Approach 1:
The pockets are pre-formed in the cage structure with defined axial positions before assembly. The bearing rollers are positioned in these pre-formed pockets, which already provide axial location. This preliminary preparation of the cage structure eliminates the need for additional axial positioning steps during assembly, while ensuring proper spacing from the annular spring.
Solution Approach 2:
The webs between the pockets serve as intermediaries that define the axial position of the bearing rollers. The webs are positioned at specific axial locations in the cage, and the rollers are constrained by these webs. This intermediary structure provides the necessary axial positioning while maintaining simplicity in the assembly process.
3Reliability
If additional anti-friction bearing is used separately from the freewheel, then the shaft and hub can be mounted without play, but the axial structural dimension increases
Solution Approach 1:
The anti-friction bearing function is merged with the freewheel cage structure by integrating bearing rollers directly into the cage pockets. The cage serves dual purposes: containing the clamping bodies for the freewheel function and housing the bearing rollers for the anti-friction bearing function. This combination eliminates the need for separate bearing components, reducing the axial structural dimension while maintaining radial mounting precision.
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, prevents roller loss, reduces assembly forces, and enhances functionality by ensuring secure bearing roller positioning and increased torque transmission capabilities.
Implementation Method 1
the freewheel cage is produced from an elastically deformable plastic, in particular as an injection molded part, and the bearing rollers are clipped into their pockets by way of elastic deformation of the cage
Data Source
AI summary
A cage freewheel for installation into the clamping gap of a shaft/hub connection, in particular in an e-bike drive, includes an annular cage with, following one another in the circumferential direction, bearing rollers for mounting the hub and the shaft together, and clamping bodies arranged pivotably in the cage. The clamping bodies block a relative movement between the shaft and the hub in a frictionally locking manner in one rotational direction, and allow rotation in the other rotational direction, and are spring-loaded in the coupling direction by an annular spring which extends around the row of the clamping bodies in a slot in the radially outer surface of the clamping bodies. The bearing rollers are arranged in each case in pairs in associated pockets of the cage on both sides of the annular spring. Here, the bearing rollers are received in a positively locking manner in the associated pockets.