Segmented Chain-Ring Shifting via Axial Displacement
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Solution Overview
Problem
Current bicycle transmission systems face inefficiencies and reliability issues due to the complexity and friction associated with shifting between chain-rings, particularly with the front derailleur, which requires more force and results in abrupt shifting and increased wear.
Innovation Solution
A power transmission system featuring a first chain-ring and a second chain-ring with more teeth, segmented into movable segments that can axially displace between configurations, utilizing guiding means and drivers to facilitate smooth shifting without a traditional derailleur, leveraging the chain's tension to stabilize and shift the segments, and constraint means to ensure efficient power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional front derailleur is used to shift between chain-rings, then gear ratio changes can be achieved, but the system requires high driving force, generates increased friction and wear, and produces abrupt shifting
Solution Approach 1:
The second chain-ring is divided into multiple segments that can independently move axially relative to the first chain-ring. This segmentation allows the chain to engage with different portions of the second chain-ring sequentially, enabling smooth gear shifts without requiring high force from a traditional derailleur mechanism
Solution Approach 2:
The chain itself provides the force to move the segments axially through its tension and engagement geometry. When the chain engages with the segments at an angle, the chain's own tension generates the axial component of force that drives the segments between chain-rings, eliminating the need for an external derailleur mechanism
2Adaptability or versatility
If chain-ring shifting is performed with a front derailleur, then transmission ratio changes are possible, but the system experiences increased wear and friction
Solution Approach 1:
The segments are designed to be movable rather than fixed, allowing them to dynamically adjust their axial position in response to chain engagement forces. This dynamic behavior enables the system to adapt transmission ratios smoothly while minimizing friction through natural chain-driven movement rather than forced mechanical shifting
Solution Approach 2:
The chain's tension, which normally creates friction and wear in traditional derailleur systems, is converted into a beneficial force that naturally drives the segments axially. The angular engagement between the chain and segments transforms the chain's pulling force into the axial movement needed for shifting, turning a source of energy loss into the driving mechanism
3Adaptability or versatility
If multiple sprockets are combined with chain-rings to increase transmission ratios, then gear range is expanded, but the complexity of sequential shifting increases
Solution Approach 1:
By segmenting the second chain-ring, the system creates multiple engagement points that can be accessed sequentially as the chain moves. This segmentation provides a natural progression path for shifting through multiple transmission ratios without requiring complex derailleur sequencing, as each segment represents a discrete gear position
Solution Approach 2:
The segments serve multiple functions: they form the teeth of the second chain-ring for power transmission, provide the axial movement mechanism for shifting, and create the engagement geometry that guides the chain during transitions. This multi-functionality eliminates the need for separate shifting mechanisms for each gear ratio change
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 solution reduces the required driving force for shifting, allows for more compact and lightweight drivers, minimizes wear and friction, and enhances the stability and smoothness of chain-ring shifts, improving the overall efficiency and reliability of the transmission system.
Implementation Method 1
leveraging the chain's tension to stabilize and shift the segments
Implementation Method 2
The relative movement of each tooth of the segments with respect to the first chain-ring has a tangential component having the sense of the chain traction
Data Source
AI summary
Chain-rings set for bicycle including a first chain-ring and a second chain-ring, this latter formed by segments, which includes displacement means with axial component of the segments with respect to the first chain-ring such that they can be moved a the chain free zone ZLC and shift the chain among chain-rings, where the axial displacement means are formed by guiding means configured for guiding the segments such that the relative movement of the teeth of the segments with respect to the small chain-ring in its displacement from a first disengagement configuration to a second engagement configuration has a tangential component opposite to the forward direction.