Seal Lip Texture and Grease Viscosity for Friction Control

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Solution Overview

Problem

Existing sealing devices with concavities and convexities on the lip contact surface suffer from increased sliding abrasion and deteriorated sealing performance due to high friction, which is not effectively addressed by prior art solutions.

Innovation Solution

Applying concavities and convexities to the sliding surfaces of the seal lips and using low base oil viscosity grease, while maintaining a smooth surface on the other member, reduces friction and prevents wear by minimizing contact area and utilizing lubrication effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If concavities and convexities are applied to the lip slidable contact surface, then friction is reduced, but sliding abrasion of the seal lip is promoted

Engineering Contradiction:
Improvefriction forceVSAvoidsealing performance
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The invention applies different surface qualities to different locations: the seal lip sliding surface has concavities and convexities for low friction, while the other member's contact surface remains smooth. This local differentiation allows the seal lip to slide with reduced friction on the textured surface while maintaining sealing contact on the smooth surface, preventing abrasion and deterioration of sealing performance.

Inventive Principle:
Principle #3Local quality

2Force

If concavities and convexities are applied to reduce contact area, then friction force is reduced, but seal lip wear increases

Engineering Contradiction:
Improvefriction forceVSAvoidseal service life
Core Design Contradiction:
ForceVSDuration of action of moving object

Solution Approach 1:

The invention creates a localized textured surface on the seal lip while keeping the mating surface smooth. This allows reduced friction during sliding motion through the concavities and convexities, but maintains proper sealing contact and distributes wear appropriately, extending the seal's service life without compromising durability.

Inventive Principle:
Principle #3Local quality

3Force

If low base oil viscosity grease is used, then friction force is reduced, but lubrication effectiveness may be compromised

Engineering Contradiction:
Improvefriction forceVSAvoidlubrication performance
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The invention changes the viscosity parameter of the grease to a lower base oil viscosity value, which reduces friction force during sliding. The concavities and convexities on the seal lip work synergistically with this lower viscosity grease to maintain effective lubrication while achieving the desired low friction state, thus improving fuel efficiency without sacrificing lubrication performance.

Inventive Principle:
Principle #35Parameter changes

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 achieves low friction during sliding motion and suppresses lip abrasion, maintaining sealing performance while improving fuel efficiency by reducing frictional forces and extending seal service life.

Implementation Method 1

a low base oil viscosity grease is supplied to the sliding surfaces of the seal lips... the grease easily intervenes by the concavities and convexities. Accordingly, a friction force is reduced.

Methodology Applied
Scientific EffectLubrication: Lubrication

Data Source

PatentEP2687761B1Sealing device
Publication Date: 2018.01.03 NOK CORP
  • EP2687761B1 patent drawingFigure 1
  • EP2687761B1 patent drawingFigure 2~3
  • EP2687761B1 patent drawingFigure 4~5

AI summary

In a sealing device having a seal lip which slidably comes into close contact with the other member, the sealing device can achieve a low friction in conjunction with the sliding motion and can suppress the lip abrasion. In order to achieve the object, in a sealing device having a seal lip which slidably comes into close contact with the other member, for simultaneously achieving a reduction of a frictional force in the sliding motion and a suppression of the lip abrasion, concavities and convexities are applied to a sliding surface of the seal lip and a low base oil viscosity grease is supplied to the sliding surface of the seal lip. The concavities and convexities have a magnitude between 1.0 and 3.0 µmRa, as to the low base oil viscosity grease, it is desirable to employ a grease in which a base oil kinetic viscosity at 40 ºC is between 10 and 40 mm2/s.