Segmented Sprocket Gearbox Shifting Without Chain Displacement
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Solution Overview
Problem
Current bicycle gearbox technologies face challenges in efficiently shifting gears while protecting the gearing system from dirt and moisture, and optimizing weight distribution for improved bicycle handling.
Innovation Solution
The implementation of segmented sprockets with a shifting system that includes a gear cluster with independently movable gear segments, radially transitionable sliders, and a toggle mechanism to change gear ratios without displacing the chain or belt laterally, allowing for efficient gear shifting within a protected and centrally mounted gearbox.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional gearbox with lateral chain displacement is used for gear shifting, then gear ratio changes can be achieved, but the chain or belt must be displaced laterally which increases mechanical wear and reduces reliability
Solution Approach 1:
The patent transitions from lateral chain displacement (horizontal dimension) to vertical gear segment movement. The gear segments move in and out of the plane of rotation, allowing the chain to remain in its original lateral position while still achieving gear ratio changes. This dimensional change eliminates the harmful lateral displacement of the chain.
Solution Approach 2:
The gear is divided into multiple independent segments that can move relative to each other. Each segment can be independently positioned in or out of the plane of rotation, allowing selective engagement with the chain. This segmentation enables gear ratio changes without requiring the entire gear or the chain to move laterally.
2Weight of moving object
If the gearbox is centrally mounted on the bicycle frame, then weight distribution is optimized for better handling, but the gearing system becomes more vulnerable to impacts and environmental factors
Solution Approach 1:
The patent employs a sealed gearbox housing that encloses the gearing system, protecting it from dirt and moisture. The housing acts as a barrier that allows the gearbox to be mounted in the optimal central location without exposing the internal components to environmental factors. The sealed enclosure maintains protection while enabling flexible mounting positioning.
3Reliability
If segmented gears with independent movement are used, then smooth gear shifting without lateral chain displacement is achieved, but the device complexity increases due to additional components like sliders and toggles
Solution Approach 1:
The patent uses dynamic elements such as spring-loaded sliders and toggle mechanisms that automatically engage and disengage gear segments based on operational conditions. The spring-loaded sliders provide continuous contact force to maintain engagement, while the toggle mechanism enables smooth transitions between gear segments. These dynamic components reduce the need for complex control systems while maintaining reliable shifting operation.
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 enables smooth and efficient gear shifting, protects the gearing system from environmental factors, and optimizes weight distribution for better bicycle handling by allowing gear ratios to be changed without displacing the chain or belt, enhancing the overall performance and reliability of the bicycle drivetrain.
Implementation Method 1
pivoting a toggle into a first position such that a first ramped face of the toggle is in a path of the one or more protrusions of the sliders; and sequentially moving each segment of the first gear out of the plane of the power transfer mechanism by urging the slider radially when the one or more protrusions strike the first ramped face of the toggle
Data Source
AI summary
A gearbox may include a drive spindle and several interconnected gear clusters arranged in a housing. A first of the gear clusters is coaxially fastened to the spindle, and has an outboard gear and an inboard gear. The first gear cluster drives a belt or chain to operate one or more of the other gear clusters, and the inboard gear is physically divided into a plurality of segments. A shifting system for the gearbox includes an actuator configured to urge the segments of the inboard gear of the first gear cluster into and out of the plane of the belt or chain via a toggle and slider mechanism, such that a gear ratio of the gearbox is changeable without displacing the belt or chain out of the plane.