Bicycle Sprocket Assembly With Through Splines and Lock Ring

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Solution Overview

Problem

Existing bicycle transmission devices require high-tonnage extrusion forging for non-through spline structures, leading to increased manufacturing complexity and costs.

Innovation Solution

A new assembly structure featuring a penetrating spline design for sprockets, allowing for assembly without the need for high-tonnage extrusion forging, by using a first sprocket with through splines and a second sprocket with through holes, and a lock ring for secure assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If non-through spline structures are used in sprockets, then the spline can provide secure engagement, but high-tonnage extrusion forging is required which increases manufacturing complexity and costs

Engineering Contradiction:

Improvespline engagement securityVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The spline structure is divided into multiple independent through-splines rather than a single non-through spline. Each through-spline extends completely through the sprocket body, allowing them to be manufactured separately and then assembled together, eliminating the need for high-tonnage extrusion forging while maintaining secure engagement through the cumulative effect of multiple splines

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of creating a single non-through spline structure that requires complex extrusion forging, the invention inverts the approach by using multiple through-splines that can be more easily manufactured and then assembled. This inversion of the structural approach simplifies the manufacturing process while achieving the same functional result of secure spline engagement

Inventive Principle:

Principle #13The other way round (Inversion)

2Strength

If non-through spline structures are used, then the spline can maintain structural integrity, but high mold strength and machine capability are required which increases production costs

Engineering Contradiction:

Improvespline structural integrityVSAvoidproduction costs

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The spline system is segmented into multiple independent through-splines that can be manufactured using standard equipment rather than requiring high-tonnage extrusion forging. Each spline maintains its own structural integrity while the collective arrangement provides the necessary overall strength, and the manufacturing cost is reduced because standard machinery can be used instead of specialized high-capacity equipment

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention inverts the conventional approach by replacing the single non-through spline design with multiple through-splines. This inversion allows the use of standard manufacturing equipment with lower capacity requirements, thereby reducing production costs while maintaining structural integrity through the distributed arrangement of multiple splines

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If non-through spline structures are used, then the spline can provide adequate engagement, but high-tonnage extrusion forging is required which increases device complexity

Engineering Contradiction:

Improvespline engagementVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The spline engagement system is segmented into multiple independent through-splines that can be manufactured using simpler, standard processes rather than complex high-tonnage extrusion forging. Each through-spline provides its own engagement function, and the overall system reliability is achieved through the cumulative effect of these simpler components, thereby reducing the complexity of the manufacturing process

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention inverts the conventional design by replacing the single non-through spline requiring complex extrusion forging with multiple through-splines that can be manufactured using standard processes. This inversion simplifies the manufacturing process complexity while maintaining adequate engagement through the distributed arrangement of multiple simpler spline elements

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS12539939B2Transmission device for bicycle

Publication Date: 2026.02.03 SUN RACE STURMEY ARCHER

AI summary

A transmission device for bicycle comprises a sprockets cluster, a second sprocket and a lock ring. The sprockets cluster has plural sprockets, one of the sprockets is a first sprocket, which has a first sprocket teeth, a protrusion of first sprocket and plural splines of first sprocket. The second sprocket has a second sprocket teeth, a protrusion of second sprocket, plural splines on second sprocket, and an opening of second sprocket. The lock ring is disposed in the opening of second sprocket.