Bicycle Hub Transmission With Planetary Coupling for Quiet 1:1 Drive
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Solution Overview
Problem
Existing bicycle transmissions with a fixedly connected sun gear to the wheel axle produce audible noise and losses in the actuator during 1:1 transmission, which is undesirable in high-end bicycles.
Innovation Solution
A transmission system with a planetary gear set having three rotational members, including a ring wheel, planet carrier, and sun wheel, where the sun wheel is engageable with the wheel axle, and a switching mechanism with switchable couplings and one-way clutches to optimize torque transfer and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sun wheel is fixedly connected to the wheel axle, then the transmission structure is simple and reliable, but audible noise and actuator losses occur during 1:1 transmission
Solution Approach 1:
The patent applies the dynamics principle by making the connection between the sun wheel and wheel axle flexible rather than fixed. The coupling means allow relative movement and adjustment, enabling the transmission system to dynamically adapt its configuration. This flexibility eliminates the rigid contact that causes noise and energy losses during 1:1 transmission, while maintaining reliable torque transfer through controlled engagement.
Solution Approach 2:
The patent implements parameter changes by allowing the coupling means to vary the transmission ratio and engagement characteristics. By changing the operational parameters of the coupling (such as engagement depth, relative position, and stiffness), the system can optimize performance for different operating conditions, reducing noise and losses during 1:1 transmission while maintaining reliability.
2Object-generated harmful factors
If the sun wheel is engageable with the wheel axle through coupling means, then noise and losses are reduced, but the device complexity increases
Solution Approach 1:
The patent uses coupling means as an intermediary element between the sun wheel and wheel axle. This intermediary component serves multiple functions: it reduces noise and losses by providing flexible engagement, while also simplifying the overall structure compared to complex adjustable mechanisms. The coupling means act as a mediator that achieves noise reduction without requiring complex control systems or multiple components.
3Object-generated harmful factors
If flexible coupling means are used between the sun wheel and wheel axle, then noise is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by designing the coupling means with adjustable engagement parameters that can be optimized during manufacturing and assembly. By allowing variation in engagement depth, stiffness, and relative positioning, the system can achieve noise reduction while accommodating normal manufacturing tolerances. The coupling design incorporates parameters that can be tuned to balance noise reduction with manufacturing feasibility.
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
The solution effectively reduces noise and losses in the actuator, enhancing the performance and quiet operation of high-end bicycles by allowing flexible coupling and efficient torque distribution.
Implementation Method 1
a planetary gear set which is present in the transmission housing and is provided with three rotational members, of which a first rotation body forms a ring wheel and is connected to the transmission housing, a second rotation body forms a planet carrier and is connected to the coupling means and a third rotation body forms a sun wheel and is engageable with the wheel axle
Data Source
Figure 1~2
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Figure 7~9
AI summary
A transmission intended to be mounted on a rear wheel axle 3 of a bicycle between a sprocket carrier 31 and a wheel hub 201 has a transmission housing 33, which is provided with connecting means 35, 37 for the connection of the sprocket carrier to the transmission housing, as well as coupling means 41 for coupling the transmission to the hub 201. The transmission further has a planetary gear set which is present in the transmission housing and is provided with three rotational members, of which a first rotation body 47 is connected to the transmission housing 33, a second rotation body 51 is connected to the coupling means 41, and a third rotation body 53 can be coupled with the wheel axle 3. The first rotation body 47 is connected via a first clutch 71 to the second rotation body 51 and the third rotation body 53 is connected to a second clutch 73 via which the third rotation body can be connected to the wheel shaft 3.