Bicycle Freewheel Locking Body Arrangement for Compact Torque Transfer
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Solution Overview
Problem
Existing freewheel hubs face challenges in efficiently transmitting torque while being lightweight, compact, and cost-effective, as they either require larger components to handle forces or are expensive to manufacture, especially when using axial freewheels or rotationally moving pawls.
Innovation Solution
The design incorporates a locking body arrangement with a planar coupling surface that transmits force tangentially, using multiple locking bodies and a biasing device like a spring to ensure effective torque transmission with reduced manufacturing costs, and can include a combination of locking slides and pawls for enhanced stability and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If rotationally moving pawls are used to transmit torque, then the freewheel hub can be simpler in structure, but the components must be built larger or transmit lower forces due to high radial force components
Solution Approach 1:
The invention transitions from radial force transmission (conventional pawls) to axial force transmission by designing the coupling surface perpendicular to the rotation axis. This dimensional change allows the locking body to transmit torque through axial pressing force rather than radial components, enabling compact design while maintaining high torque capacity.
Solution Approach 2:
The invention changes the orientation parameter of the coupling surface from radial to axial direction. By making the coupling surface perpendicular to the rotation axis, the force transmission direction changes fundamentally, allowing the locking body to engage with the driving toothing in a manner that transmits torque through axial compression rather than radial leverage.
2Force
If axial freewheels with axial gearing are used, then large forces can be transmitted with compact dimensions, but manufacturing costs increase
Solution Approach 1:
The invention extracts the essential feature of axial force transmission from complex axial gearing systems and implements it through a simplified locking body mechanism. By removing the need for intricate gear arrangements and using a single locking body with an axial coupling surface, the design achieves axial force transmission capability without the manufacturing complexity and cost of traditional axial freewheels.
Solution Approach 2:
The invention replaces expensive, complex axial gearing components with a simpler, more manufacturable locking body design. The simplified structure uses fewer precision-machined parts and can be manufactured with standard processes, significantly reducing production costs while maintaining the ability to transmit large forces.
3Force
If the coupling surface is designed as a planar area, then force can be transmitted more effectively, but the locking body requires higher manufacturing precision
Solution Approach 1:
The invention changes the orientation of the coupling surface to be perpendicular to the rotation axis rather than parallel. This dimensional reorientation transforms the force transmission from a sliding contact mechanism to a pressing contact mechanism, where the planar surface presses against the driving toothing. This approach maintains effective force transmission while reducing sensitivity to manufacturing tolerances.
Solution Approach 2:
The invention changes the geometric parameters of the coupling surface orientation and the engagement mechanism. By transitioning from a sliding interface to a pressing interface, the design reduces the criticality of surface flatness and alignment tolerances, allowing for more relaxed manufacturing precision while maintaining high force transmission efficiency.
4Force
If multiple locking bodies are used to increase torque capacity, then the torque transmission capability improves, but the device complexity increases
Solution Approach 1:
The invention divides the torque transmission function into multiple identical locking bodies arranged circumferentially. Each locking body is a simple, standardized component that engages independently with the driving toothing. This segmentation allows torque capacity to be increased by simply adding more identical units rather than designing a single complex locking mechanism.
Solution Approach 2:
The invention designs all locking bodies with identical structure and function, making them universal interchangeable components. Each locking body performs the same torque transmission function, and they can be manufactured using the same process. This universality simplifies manufacturing and assembly while allowing flexible scaling of torque capacity by adjusting the number of locking bodies.
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 allows for efficient torque transmission with reduced component size and material usage, enabling the freewheel hub to be adaptable to various applications while maintaining low production costs and high precision, similar to axial freewheels but with improved stability and reduced precision demands.
Implementation Method 1
a preloading device which is configured to preload the locking body towards the locking position
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A freewheel hub 10 for a bicycle comprises: a driver 16 and a hub sleeve 14, each rotatably mounted about a common axis of rotation X on a hub axle 12; a locking element assembly 18 with at least one locking element 20, which is adjustably mounted between a locked position and a release position in a radial locking element recess 22; and a preloading device 24 configured to preload the locking element 20 towards the locked position, wherein the locking element recess 22 is provided in one component consisting of the driver 16 and hub sleeve 14, while the other component has a radial drive toothing 26 or is rotationally fixed to it, wherein the surface of the locking element 20 has a coupling surface 35 which, in the locked position, bears against a contact surface 45 of the locking element recess 22, while an engagement section 33 of the locking element 20 engages the drive toothing. 26 intervenes,so that when the driver 16 rotates in a first direction of rotation R1 about the axis of rotation X, torque is transmitted from the driver 16 to the hub sleeve 14 via the coupling surface 35, and wherein the locking element 20 in the release position allows rotation of the hub sleeve 14 in the first direction of rotation R1 relative to the driver 16, and wherein more than half of the coupling surface 35 is designed as a planar area 36.