Segmented Bicycle Sprocket Shifting Without Belt Displacement

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Solution Overview

Problem

Existing bicycle gearboxes face challenges in efficiently shifting gears without displacing the belt out of its plane, leading to potential misalignment and reduced durability due to exposure to elements and increased weight distribution affecting bike handling.

Innovation Solution

A gearbox design featuring segmented sprocket clusters with a shifting system that includes a wedge mechanism to pivot gear segments in and out of the belt plane, allowing for gear ratio changes without displacing the belt, thus maintaining alignment and protecting components from the environment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional gear shifting mechanisms are used, then gear ratio changes can be achieved, but the belt is displaced out of its plane causing misalignment and reduced durability

Engineering Contradiction:

Improvegear ratio change capabilityVSAvoidbelt alignment and durability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The inboard gear is divided into multiple segments that can independently pivot relative to the gear body. This segmentation allows individual segments to be selectively positioned into or out of the belt plane, enabling gear ratio changes while keeping the belt plane stable and aligned.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The gear segments are made dynamically adjustable through pivoting motion controlled by the shifting system. The segments can transition between fixed positions (in plane or out of plane) based on shifting actuation, allowing the gear cluster to adapt its configuration without displacing the belt from its plane.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If gear segments are displaced to change ratios, then gear shifting is achieved, but components become exposed to elements reducing durability

Engineering Contradiction:

Improvegear shifting capabilityVSAvoidexposure to dirt and moisture

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The segmented gear structure allows non-active segments to be nested or positioned within the gear cluster assembly when not in use. The shifting system enables segments to be retracted into the gear body or positioned in protected locations, minimizing their exposure to external elements like dirt and moisture while maintaining gear shifting functionality.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Adaptability or versatility

If conventional shifting systems are used, then gear changes occur, but weight distribution is adversely affected impacting bike handling

Engineering Contradiction:

Improvegear ratio variabilityVSAvoidgearbox weight distribution

Core Design Contradiction:

Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

By segmenting the gear structure, the design eliminates the need for heavy external shifting mechanisms and belt displacement systems. The segmented segments can be actuated with lighter components, reducing overall gearbox weight and allowing more favorable weight distribution on the bicycle.

Inventive Principle:

Principle #1Segmentation

4Adaptability or versatility

If the belt is displaced during shifting, then gear ratios change, but misalignment occurs reducing precision

Engineering Contradiction:

Improvegear ratio adjustmentVSAvoidbelt alignment precision

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

Instead of displacing the belt to achieve gear changes (conventional approach), this invention inverts the approach by keeping the belt stationary in its plane and displacing the gear segments relative to the belt. This inversion maintains precise belt alignment while achieving gear ratio changes through segment repositioning.

Inventive Principle:

Principle #13The other way round (Inversion)

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 design enhances gear shifting precision, durability, and motor efficiency by maintaining belt alignment during shifts, reducing exposure to elements, and optimizing weight distribution for improved bike handling.

Implementation Method 1

a shifting system including a wedge mechanism to pivot gear segments in and out of the belt plane

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentUS12097929B2Bicycle gearbox having segmented sprockets

Publication Date: 2024.09.24 PRAXIS WORKS LLC

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 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, such that a gear ratio of the gearbox is changeable without displacing the belt out of the plane.