Gear-Shifting Device With Reversible Coupling For Bicycle Drivetrains
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Solution Overview
Problem
Existing gear-shifting devices for bicycles face issues such as slow gear change times, mechanical delicacy, exposure to harsh conditions, and maintenance requirements, which affect performance and efficiency, especially on rough terrain and steep gradients.
Innovation Solution
A gear-shifting device with a primary, secondary, and tertiary shaft system featuring a series of gear wheels and a coupling system with reversible connection, allowing quick and efficient gear changes through a drum with contact members and elastic elements, reducing the need for manual force during shifting and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a derailleur system with quadrilateral linkages is used, then gear shifting capability is achieved, but the device becomes mechanically delicate and requires frequent maintenance
Solution Approach 1:
The transmission system is divided into independent shafts (primary, secondary, tertiary) with discrete gear wheels that can be selectively engaged. This segmentation allows each component to be simpler and more robust, eliminating the complex interconnected linkages of derailleur systems while maintaining gear shifting capability through selective mechanical engagement.
Solution Approach 2:
The patent replaces the delicate quadrilateral linkage mechanism with a direct mechanical engagement system using shafts and gear wheels. The coupling system with reversible connection provides a more robust mechanical interface that eliminates the need for precision-adjusted linkages, thereby improving reliability and reducing maintenance requirements.
2Adaptability or versatility
If traditional gear-shifting mechanisms are used, then gear ratio changes are possible, but the gear change time is slow
Solution Approach 1:
Multiple gear wheels are pre-positioned on the shafts in different locations along the axial direction. The coupling system is designed to rapidly engage or disengage these pre-positioned gears, eliminating the need for gradual adjustment during shifting. This preliminary positioning of multiple gear options enables instant gear ratio changes without prolonged transition periods.
Solution Approach 2:
The coupling system incorporates reversible connection capabilities that allow dynamic engagement and disengagement of gear wheels. This dynamic mechanism enables rapid switching between different gear ratios by simply coupling or decoupling shafts, significantly reducing gear change time compared to traditional gradual adjustment mechanisms.
3Adaptability or versatility
If complex mechanical linkage systems are used, then gear selection is possible, but the device complexity increases
Solution Approach 1:
The transmission system is divided into independent shafts (primary, secondary, tertiary) with discrete gear wheels that can be selectively engaged. This segmentation allows each component to be simpler and more robust, eliminating the complex interconnected linkages of derailleur systems while maintaining gear shifting capability through selective mechanical engagement.
Solution Approach 2:
The coupling system with reversible connection serves multiple functions: it enables gear engagement, provides disengagement capability, and allows for different gear ratio selections. This multi-functional design eliminates the need for separate mechanisms for each function, thereby reducing overall device complexity while maintaining full gear selection capability.
4Adaptability or versatility
If derailleur systems are used, then gear ratio changes can be made, but manual force and adjustment are frequently required
Solution Approach 1:
The shaft and gear wheel design allows for self-aligning engagement through the coupling system. The reversible connection mechanism automatically maintains proper engagement without requiring frequent manual adjustment, as the rigid shaft connection naturally maintains alignment. This self-service characteristic eliminates the need for regular maintenance adjustments that plague derailleur systems.
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 device enables faster gear changes, increased riding comfort, and improved mechanical efficiency, with reduced maintenance needs and enhanced reliability, allowing efficient use on varied terrains without the need for frequent adjustments.
Implementation Method 1
at least one elastic element (42) which controls the movement of the pickup element (41) to and from the respective shaped seat (43) of the shaft (30)
Data Source
Figure 1
Figure 1A
Figure 2
AI summary
Described is a gear-shifting device (1) for means of transport comprising a pair of shafts (20-30) each comprising a plurality of transmission units (200) wherein each transmission unit (200) of a shaft (30) is rotated by a respective transmission unit (200) of the other shaft (20) wherein the shaft (30) is an activation shaft. The activation shaft (30) comprises activation means (40) configured in such a way as to selectively rotate in an integral fashion a transmission unit (200) of the shaft (20) with a transmission unit (200) of the activation shaft (30) by generating a transient difference in speed of rotation between the slowing disk (45) operatively connected to the transmission unit (200) of the shaft (30) and the transmission unit (200) of the shaft (30). The transmission units (200) of the activation shaft (30) rotate freely relative to the activation shaft (30) in a selected configuration of the transmission unit (200).