Beveled Chainring Teeth for Roller Chain Retention

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Traditional chainrings face issues with roller chain retention due to varying approach angles as different rear gears are selected, leading to potential disengagement and retention problems.

Innovation Solution

The chainring design incorporates bevel features that align with the roller chain links, eliminating the need for clocking and enhancing retention by engaging different parts of the chain, thereby reducing misalignment and mechanical interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional chainring design is used, then manufacturing is simple, but roller chain retention is poor under varying approach angles

Engineering Contradiction:

Improveroller chain retentionVSAvoidchainring structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The chainring tooth is divided into multiple functional segments: the tooth tip for engagement, the tooth flanks for force transfer, and the bevel surfaces for alignment. This segmentation allows each portion to perform its specific function optimally, with bevels providing alignment tolerance and teeth providing secure engagement, thereby improving chain retention without requiring complex external alignment mechanisms

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention adds a bevel dimension to the traditional tooth profile, transitioning from a two-dimensional tooth face to a three-dimensional structure with angled surfaces. These bevels create a conical engagement geometry that accommodates lateral approach angle variations, allowing the chain to self-align as it approaches the chainring from different angles, thus improving reliability without increasing overall device complexity

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If chainring teeth are designed for precise engagement, then chain retention is improved, but clocking alignment becomes necessary

Engineering Contradiction:

Improvechain retentionVSAvoidinstallation alignment

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The invention changes the geometric parameters of the tooth engagement surface by introducing bevel angles. Instead of relying on precise planar alignment, the beveled surfaces create an angular tolerance zone that accommodates variations in approach angle. This parameter change allows the chain to engage correctly across a range of alignment conditions, eliminating the need for precise clocking during installation while maintaining secure retention

Inventive Principle:

Principle #35Parameter changes

3Strength

If bevel features are added to chainring, then force distribution is improved, but manufacturing complexity increases

Engineering Contradiction:

Improveforce transfer distributionVSAvoidchainring fabrication

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The bevel features are applied locally to specific portions of the tooth structure rather than requiring complex modifications to the entire chainring. The bevels are concentrated at the tooth flanks and roots where force transfer occurs, providing localized stress distribution improvement without requiring complex manufacturing processes for the entire component. This localized application maintains ease of manufacture while achieving better force distribution

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11359709B2Chainring

Publication Date: 2022.06.14 FOX FACTORY INC

AI summary

A chainring is disclosed. The chainring includes a plurality of teeth about the outer perimeter of the chainring; and a chain retention feature at a root of one or more of the plurality of teeth and traversing at least a portion of a circumference of the chainring, the chain retention feature to align with at least a portion of a roller chain and assist in a retention of the roller chain on the chainring.