Bicycle Rear Axle Cogset Shifting for Chain Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing bicycle gear systems suffer from chain wear, increased risk of chain breakage, limited gear options, and complex wheel replacement processes due to the chain's inclined operation and the need for structural modifications to the bicycle frame.
Innovation Solution
A transmission gear selection system that keeps the chain straight and axial by moving the cogset relative to the wheel hub, allowing for easy wheel replacement without modifying the bicycle frame, using a central supporting axle and hub member with a rotatable cogset and movement means that adjust the cogset's position between extreme positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the chain operates in an inclined position with respect to the teeth of the cogs and crown gears to enable gear shifting, then gear selection capability is improved, but chain wear increases and chain breakage risk increases
Solution Approach 1:
Instead of moving the chain at an angle to shift gears, the patent inverts the approach by moving the cogset axially relative to the chain. The chain remains straight and perpendicular to the cogs throughout operation, while the entire cogset shifts position along the axle to achieve gear selection. This eliminates the inclined operation that causes chain wear and breakage.
Solution Approach 2:
The patent transitions from lateral chain movement (horizontal dimension) to axial cogset movement (vertical dimension along the axle). By changing the dimension of movement from side-to-side chain displacement to front-to-back cogset displacement, the chain maintains its optimal perpendicular orientation to the cog teeth while gear selection is still achieved.
2Adaptability or versatility
If the chain operates in an inclined position with respect to the teeth of the cogs and crown gears to enable gear shifting, then gear selection capability is improved, but energy transmission efficiency deteriorates due to lateral force components
Solution Approach 1:
The patent inverts the traditional gear shifting mechanism by keeping the chain straight and perpendicular to the cogs, while moving the cogset axially instead of moving the chain laterally. This eliminates the lateral force components that cause energy loss, as all applied force is transmitted directly through the chain to the cog teeth without angular deviation.
3Adaptability or versatility
If the maximum number of gears is increased by adding more cogs and crown wheels, then gear options are improved, but device complexity increases
Solution Approach 1:
The patent employs a dynamic cogset that can shift its axial position to bring different cogs into engagement with the chain. Instead of having multiple fixed crown wheels, a single adjustable cogset provides multiple gear ratios by selectively positioning different-sized cogs at the chain interface. This dynamic repositioning reduces complexity compared to static multi-crown-wheel systems.
Solution Approach 2:
The movable cogset serves multiple functions: it provides gear selection capability, maintains chain alignment, and enables variable gear ratios all through a single integrated component. This multi-functional design eliminates the need for separate mechanisms for each function, reducing overall system complexity.
4Device complexity
If the cogset is fixed to the wheel hub to simplify structure, then device complexity is reduced, but wheel replacement becomes difficult and time-consuming
Solution Approach 1:
The patent segments the wheel assembly into three independent components: the wheel rim with spokes, the hub, and the cogset. The cogset is mounted on the axle rather than fixed to the hub, allowing the wheel rim and hub to be removed as a unit while the cogset remains on the axle. This segmentation enables rapid wheel replacement without disturbing the gear selection mechanism.
5Weight of moving object
If the chain and cogs are made with reduced thickness to reduce weight and facilitate engagement, then weight is reduced, but strength decreases and breakage risk increases
Solution Approach 1:
By inverting the gear shifting mechanism to move the cogset axially rather than angling the chain, the patent eliminates the need for specially shaped, thin-walled cogs and chains designed to accommodate inclined operation. Standard, thicker, and stronger chain and cog components can be used since they only need to handle perpendicular loading, thereby increasing strength while maintaining reasonable weight.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The selection system of the transmission gear in bicycles or the like comprises: • - one central supporting axle (2) of a wheel of a bicycle associated with a pair of forks (F1, F2) of the bicycle; • - one cogset (4) associated rotatable and axially sliding with the central supporting axle (2); • - movement means (6) of the cogset (4) on the central supporting axle (2); wherein the central supporting axle (2) comprises a first end (7) associated in a removable manner with a first fork (F1) and a second end (8) associated axially sliding with a second fork (F2), the central supporting axle (2) being movable sliding with respect to the forks (F1, F2) between a working position, wherein it is interposed between them, and a disassembly position, wherein it is at least partly pulled out of them through the second fork (F2) for the removal/assembly of the wheel.