Bicycle Rear Sprocket Adapter with Optimized Internal Pitch Angle

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Solution Overview

Problem

Bicycle rear sprocket adapters face challenges in compatibility with non-complementary engagement structures between the rear sprocket assembly and hub assembly, limiting material choices and durability.

Innovation Solution

A bicycle rear sprocket adapter with external and internal spline teeth configured at specific pitch angles, allowing for mounting even with non-complementary structures, and featuring adjustable diameters and driving surfaces to enhance strength and compatibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the internal spline teeth are arranged with a larger pitch angle, then the number of internal spline teeth decreases, but the manufacturing complexity and compatibility with non-complementary structures improves

Engineering Contradiction:

Improvecompatibility with non-complementary engagement structuresVSAvoidnumber of internal spline teeth

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent applies parameter changes by optimizing the pitch angle of internal spline teeth to a specific range (10-20 degrees) to achieve the optimal balance between the number of teeth and engagement compatibility. This parameter optimization allows the adapter to work with non-complementary structures while maintaining sufficient tooth count for durability.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the internal-spline minor diameter is reduced, then the adapter can fit smaller hub assemblies, but the strength and durability of the adapter decreases

Engineering Contradiction:

Improvecompatibility with different hub assembly sizesVSAvoidstrength of internal spline teeth

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The patent applies parameter changes by establishing a specific range for the internal-spline minor diameter (25-30 mm) that balances adaptability to different hub sizes with maintaining sufficient strength. This optimized parameter range ensures the adapter can fit various hub assemblies while preserving the structural integrity of the spline teeth.

Inventive Principle:

Principle #35Parameter changes

3Strength

If the radial length of internal-spline driving surfaces is increased, then the strength and durability of the adapter improves, but the overall size and weight of the adapter increases

Engineering Contradiction:

Improvestrength of internal spline teethVSAvoidweight of adapter

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The patent applies parameter changes by optimizing the radial length of internal-spline driving surfaces to a specific range that provides sufficient strength while controlling weight. This optimized parameter ensures the adapter has adequate load-bearing capacity without excessive weight gain.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10968998B2Bicycle rear sprocket adapter

Publication Date: 2021.04.06 SHIMANO INC

AI summary

A bicycle rear sprocket adapter comprises a plurality of external spline teeth and a plurality of internal spline teeth. The plurality of external spline teeth is configured to engage with a bicycle rear sprocket assembly. The plurality of internal spline teeth is configured to engage with a bicycle hub assembly. At least two internal spline teeth of the plurality of internal spline teeth are circumferentially arranged at a first internal pitch angle with respect to a rotational center axis of the bicycle hub assembly. The first internal pitch angle ranges from 10 degrees to 20 degrees.