Bicycle Chain Outer Link Protrusions for Smoother Tooth Guidance

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Solution Overview

Problem

Existing bicycle chains with alternating inner and outer links face challenges in smooth engagement with chainrings due to insufficient protrusions, leading to noise and poor guidance of teeth between link plates.

Innovation Solution

The chain design features protrusions on the inner surfaces of outer link plates, reducing the distance between these surfaces and improving the guidance of teeth on the chainring, with optimized dimensions and shapes to enhance engagement and reduce noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If protrusions are added to outer link plates to improve tooth guidance, then engagement smoothness improves, but the distance between outer link plates increases

Engineering Contradiction:

Improveengagement smoothnessVSAvoiddistance between outer link plates

Core Design Contradiction:

Ease of operationVSLength of moving object

Solution Approach 1:

The protrusions are integrated into the existing outer link plate structure, nesting the guidance features within the available space between link plates rather than adding external components that would increase the overall distance

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The protrusions are strategically positioned only in specific areas where tooth guidance is needed, rather than uniformly modifying the entire outer link plate surface, thus providing localized improvement without excessive dimensional increase

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If the gap between link plates is reduced to improve tooth engagement, then engagement quality improves, but manufacturing precision requirements increase

Engineering Contradiction:

Improvegap consistencyVSAvoidmanufacturing difficulty

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The protrusion dimensions (height, width, curvature radius) are carefully optimized to achieve the desired gap reduction and engagement quality while remaining within manufacturable tolerances. The parameters are tuned to balance performance improvement with manufacturing feasibility

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The protrusions feature curved surfaces instead of sharp edges, which naturally accommodate manufacturing tolerances and reduce stress concentrations. The curved geometry provides smoother tooth engagement while being more tolerant of variations in the gap dimension

Inventive Principle:

Principle #14Spheroidality (Curvature)

Data Source

PatentUS12031611B2Bicycle chain

Publication Date: 2024.07.09 MIRANDA & IRMAO LDA

AI summary

A chain comprising an alternating succession of inner chain links and outer chain links, each inner chain link having a pair of inner link plates contacting the lateral faces of two rollers and each outer chain link having a pair of two outer link plates contacting the inner link plates of adjacent inner chain links. A pin connects two outer link plates and two inner link plates and a roller, wherein the inner surfaces of a pair of opposite outer link plates comprise protrusions in the area between the adjacent inner link plates. The circumference and/or diameter of the protrusion is at least 60% and/or maximum 140% the circumference and/or diameter of the eyes of the outer link plate.