Segmented Bicycle Sprockets for Enclosed Gearbox Shifting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing bicycle gearboxes are exposed to dirt and moisture, and when mounted away from the bicycle's center of gravity, they adversely affect handling.
Innovation Solution
A bicycle gearbox with segmented sprockets that utilize a power transfer mechanism with independently movable gear segments, allowing for shifting without lateral displacement and protected within a housing, enhancing durability and handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gearbox is mounted away from the bicycle's center of gravity, then the gearing system can be protected from exposure to dirt and moisture, but the gearbox adversely affects bicycle handling
Solution Approach 1:
The sprocket is divided into multiple independently movable segments that can pivot between engaged and disengaged positions relative to the chain, allowing gear shifting without lateral displacement of the entire gearbox assembly
2Reliability
If the gearbox is mounted away from the bicycle's center of gravity, then the gearing system can be protected from exposure to dirt and moisture, but the weight of the gearbox has a higher impact on bicycle handling
Solution Approach 1:
The gear shifting mechanism transitions from lateral displacement to radial movement of sprocket segments, changing the dimension of motion and allowing the gearbox to be positioned closer to the center of gravity without compromising shifting functionality
3Ease of operation
If gear segments are independently movable into and out of the plane of the power transfer mechanism, then gear shifting can occur without lateral displacement, but the device complexity increases
Solution Approach 1:
The sprocket segments are designed with pivot joints that allow dynamic movement between engaged and disengaged positions, enabling the segments to automatically follow the chain path during radial transitions and reducing the complexity of guidance mechanisms
Solution Approach 2:
A cam mechanism serves as an intermediary that converts the rotational motion of the gearbox into radial movement of the sprocket segments, simplifying the control of gear shifting while maintaining the benefits of non-lateral displacement
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 gearbox protects the gearing system from dirt and moisture while improving handling by maintaining the gearbox's weight distribution near the bicycle's center of gravity, enabling efficient and reliable gear shifting.
Implementation Method 1
each of the sliders has a pair of ramped cam surfaces
Data Source
AI summary
A method for shifting a segmented gear may include rotating a gear cluster including a first gear and a coaxial second gear using a power transfer mechanism (e.g., a belt or a chain). The power transfer mechanism defines a plane and is wrapped partially around the first gear. and wherein the first gear has a plurality of gear segments independently movable (e.g., pivotable or translatable) into and out of the plane. A plurality of radially transitionable sliders are rotated in tandem with the first gear, and each of the sliders is operatively coupled to a corresponding one of the gear segments of the first gear. In sequence, each segment of the first gear is moved out of the plane of the power transfer mechanism by urging the slider in a radial direction using a segment actuator, such that the power transfer mechanism wraps at least partially around the second gear.