Bicycle Gearshift Lever with Intermediate Element for Compact High Ratio
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Solution Overview
Problem
Existing bicycle gearshift levers are not suitable for children due to size and handling effort issues, as they require either a large size that is uncomfortable for small hands or a low transmission ratio that increases manipulation effort.
Innovation Solution
A gearshift lever design featuring a first and second toothed wheel coaxial with the main axis, an intermediate element with a parallel axis, and a compact structure, allowing for a high transmission ratio and reduced size to accommodate children's hands, with a cylindrical sleeve and sequential positioning means for easy gear shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the size of the gearshift lever is reduced to fit children's hands, then the lever becomes suitable for children's hand size, but the transmission ratio becomes too low requiring excessive manipulation effort
Solution Approach 1:
The patent introduces an intermediate element with an axis of rotation parallel to but distinct from the main axis, creating a two-stage transmission system. This dimensional arrangement allows the first toothed wheel to engage with the intermediate element, which in turn engages with the second toothed wheel, achieving high transmission ratio without increasing the lever's radial or axial dimensions.
Solution Approach 2:
The intermediate element acts as a mediator between the first toothed wheel and the second toothed wheel. This intermediate component enables the transmission of rotational motion while multiplying the transmission ratio, allowing the system to achieve high mechanical advantage within a compact form factor suitable for children's hands.
2Ease of operation
If the transmission ratio is increased to reduce manipulation effort, then the handling effort becomes manageable for children, but the lever size becomes too large for their hands
Solution Approach 1:
The transmission system is segmented into multiple stages: the first toothed wheel engaged with the intermediate element, and the second toothed wheel engaged with the drive element. This segmentation allows the total transmission ratio to be distributed across multiple gear interactions, achieving high mechanical advantage without requiring a single large gear that would increase the lever's overall size.
Solution Approach 2:
The patent arranges the toothed wheels and intermediate element in a nested configuration where components are positioned concentrically around the main axis. The intermediate element is arranged parallel to the main axis at a specific distance, allowing compact nesting of multiple transmission elements within a small radial envelope, thus achieving high transmission ratio in a compact lever size.
3Area of moving object
If a compact structure is used to reduce lever size, then the lever fits children's hands, but the complexity of the transmission mechanism increases
Solution Approach 1:
The intermediate element serves multiple functions: it acts as a gear wheel engaged with both the first and second toothed wheels, provides structural support for the transmission mechanism, and defines the geometric relationship between the different transmission stages. This multi-functionality reduces the need for additional separate components, thereby limiting complexity despite the two-stage transmission.
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 design provides a gearshift lever with a high transmission ratio suitable for children, reducing the effort required to manipulate the handle and control the derailleur, while maintaining a compact size and ease of use.
Implementation Method 1
coupling means configured to rotationally couple the rotary handle and the drive element so that the angular travel of the drive element is less than the angular travel of the handle rotary
Implementation Method 2
the coupling means comprise a first toothed wheel coaxial with the main axis and coupled in rotation with the rotary handle, a second toothed wheel coaxial with the main axis and coupled in rotation with the drive element
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
The lever (20) has coupling units (100) for rotatably coupling a rotary handle (26) and a drive element (28) such that angular stroke of the drive element is less than angular stroke of the handle. The coupling units include two toothed wheels (110, 130) coaxial with a main axis (X), and are rotatably coupled with the rotary handle and the drive element, respectively. An intermediate element (120) comprises a rotation axis parallel to and distinct from the main axis, where the intermediate element is rotatably coupled with the two toothed wheels.