Bottom Bracket Seal Structure for Dirt and Water Exclusion

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Solution Overview

Problem

Bottom bracket assemblies in bicycles are prone to dirt and debris ingress, leading to corrosion and degradation of components due to their low placement, which existing technologies have not adequately addressed.

Innovation Solution

The implementation of a threaded bottom bracket design featuring a combination of a polymer internal sleeve, metal cup, rotary seal, labyrinth seal, and desiccant liner to prevent water and debris from entering the ball bearing assembly, utilizing press fits, O-rings, and grease channels for enhanced waterproofing and sealing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a bottom bracket assembly is placed low on the bicycle frame for ergonomic positioning, then ease of operation is improved, but the assembly becomes more susceptible to dirt and debris ingress from the ground level

Engineering Contradiction:

Improveergonomic positioningVSAvoiddirt and debris ingress

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The bottom bracket assembly is divided into multiple sealing zones with different seal types: a first seal (labyrinth seal) at the outer perimeter and a second seal (rotary seal) at the inner perimeter. This segmentation allows each seal to address specific contamination pathways while maintaining the low ergonomic position of the bottom bracket.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A desiccant material is introduced as an intermediary substance between the internal components and the external environment. The desiccant absorbs moisture that penetrates the seals, providing an additional protective layer against corrosion without requiring the bottom bracket to be positioned higher.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If traditional sealing methods are used in bottom bracket assemblies, then device complexity is kept low, but the seals are insufficient to prevent water and debris from reaching the ball bearings

Engineering Contradiction:

Improvesealing structureVSAvoidprotection against water and debris

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

Different seal types are applied at different locations within the bottom bracket assembly based on the specific contamination risks at each position. The labyrinth seal is positioned at the outer perimeter where debris ingress is most likely, while the rotary seal is positioned at the inner perimeter where water penetration is a greater concern. This localized approach provides enhanced protection without uniformly increasing complexity throughout the entire assembly.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The sealing system combines multiple seal technologies (labyrinth seal, rotary seal) and materials (desiccant) into a composite protective structure. This composite approach leverages the strengths of each component: the labyrinth seal blocks large debris, the rotary seal prevents water penetration, and the desiccant absorbs residual moisture, together providing comprehensive protection that exceeds what any single seal could achieve alone.

Inventive Principle:

Principle #40Composite materials

3Reliability

If multiple sealing components are added to prevent contaminant ingress, then reliability is improved, but the assembly complexity and manufacturing difficulty increase

Engineering Contradiction:

Improvecontaminant preventionVSAvoidassembly construction

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The first seal and second seal are integrated into a unified bottom bracket assembly structure, with the desiccant material incorporated into the same housing. This merging of multiple protective functions into a single integrated component reduces the number of separate parts that need to be manufactured and assembled, thereby easing manufacturing complexity while maintaining comprehensive contaminant protection.

Inventive Principle:

Principle #5Merging (Combining)

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 effectively reduces the ingress of contaminants, maintaining the integrity and performance of the bottom bracket assembly by creating a sealed environment that minimizes corrosion and degradation, while maintaining low drag and ease of installation.

Implementation Method 1

a desiccant liner to prevent water and debris from entering the ball bearing assembly

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

labyrinth seal

Methodology Applied

Scientific EffectPhysical barrier: Physical Containment

Implementation Method 3

rotary seal

Methodology Applied

Scientific EffectContact sealing: Friction

Implementation Method 4

O-rings

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS12151780B2Seal structures

Publication Date: 2024.11.26 FOX FACTORY INC

AI summary

Disclosed herein is a threaded bottom bracket comprising: an internal sleeve, a ball bearing, wherein an inner race of the ball bearing is an extended inner race, a cup fit to concentrically hold the ball bearing, wherein the cup is coupled to the internal sleeve, a labyrinth, the labyrinth coupled to the ball bearing and fit to prevent water and debris from entering the ball bearing, wherein the labyrinth and the cup form a path, and a rotary seal disposed between the ball bearing and the labyrinth, the rotary seal having an external seal that seals against the extended inner race.