Seal Assembly Coating for Low-Friction Water Ingress Blocking

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Solution Overview

Problem

Frictional seals fail to adequately prevent water and moisture ingress, leading to corrosion and contamination of lubricants in machine parts, which can cause operational disruptions and breakdowns, despite recent developments like hydrophobic coatings.

Innovation Solution

A seal assembly with a chemically modified low friction coating on the counterface, extending on both sides of the contact area, combined with a hydrophobic or omniphobic material in the form of a coating, film, or ring, creating a hydrophobic barrier and a gap to prevent water ingress, while reducing friction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If traditional seal elements and seal lips are used to prevent water ingress, then protection against moisture is improved, but friction increases and sealing performance deteriorates

Engineering Contradiction:

Improvewater ingress protectionVSAvoidsealing performance

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The invention changes the surface energy parameter of the counterface by applying a hydrophobic coating, transforming it from a wettable surface to a non-wettable surface. This parameter change allows the seal lip to maintain contact while water is repelled, resolving the contradiction between water protection and sealing reliability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention replaces the mechanical sealing approach (relying on friction and contact pressure) with a chemical/surface property approach (hydrophobicity). The hydrophobic coating creates a barrier that repels water without requiring high friction or complex mechanical structures, thereby maintaining sealing performance while reducing friction

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Object-affected harmful factors

If hydrophobic coatings are added to improve water resistance, then protection against moisture is improved, but friction is not sufficiently reduced

Engineering Contradiction:

Improvemoisture ingress protectionVSAvoidfriction

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The invention uses a composite coating structure combining a PTFE-based low-friction layer with a hydrophobic surface layer. This composite material simultaneously provides both low friction properties and hydrophobic water repellency, addressing both issues together rather than separately

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If the coating is applied only on the contact area, then manufacturing is simplified, but water transport across the seal lip is not effectively prevented

Engineering Contradiction:

Improvecoating application simplicityVSAvoidwater transport prevention

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The invention extends the hydrophobic coating beyond the contact area onto the counterface surface in the radial direction. This dimensional extension creates a broader hydrophobic barrier that prevents water from reaching the seal lip contact area from the sides, effectively blocking water transport while maintaining manufacturability

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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

The solution effectively increases protection against water and moisture ingress, reduces friction, and prevents the transport of water across the seal lip, enhancing the durability and performance of frictional seals by creating a 'reverse-capillary' function that inhibits water passage.

Implementation Method 1

the chemical modification makes the coating hydrophobic. The coating of the counterface, when in use, also extend on both sides of the contact area, thereby creating a hydrophobic barrier close to the at least one seal lip

Methodology Applied

Scientific EffectHydrophobic effect: Hydrophobe

Implementation Method 2

the counterface is coated with a chemically modified low friction coating

Methodology Applied

Scientific EffectLow friction coating: Lubrication

Implementation Method 3

creating a hydrophobic barrier close to the at least one seal lip... creates a 'reverse-capillary' function that inhibits water passage

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Data Source

PatentUS11143307B2Seal assembly

Publication Date: 2021.10.12 AB SKF SKF PATENT DEPARTMENT

AI summary

A dual function coating on a counterface of a seal. The dual function provides having a low friction and being hydrophobic. This is achieved by chemically modifying a low friction coating. Gaps are included, primarily on the exterior side of a seal, one side being coated with the modified low friction coating on a counterface and the other side with a hydrophobic or omniphobic material on a seal body. The material can be in the form of a coating, film, strip, or ring depending on application, and be coated, glued, fused, mechanically attached or by any other suitable method, attached to the seal body. The gap should preferably be in the order of 0.2 to 1 mm wide, thus creating ‘reverse-capillary’ function where water cannot pass all the way through the gap.