Grease Composition for Hub Unit Bearing Anti-Fretting

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Solution Overview

Problem

Existing grease compositions for automotive hub unit bearings fail to provide adequate anti-fretting properties at low temperatures and rust prevention, as their effectiveness decreases due to increased viscosity of base oils, leading to reduced grease flowability and increased risk of rust from muddy water infiltration.

Innovation Solution

A grease composition comprising an aromatic diurea thickener, a base oil with moderate viscosity, a metal salt of oxidized wax, diphenyl hydrogen phosphate, and a rust preventive such as calcium sulfonate or calcium dinonylnaphthalenesulfonate, which are combined in specific proportions to enhance anti-fretting and rust prevention properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional grease compositions are used, then they provide adequate lubrication at normal temperatures, but they fail to provide adequate anti-fretting properties at low temperatures

Engineering Contradiction:

Improveanti-fretting propertiesVSAvoidlow temperature performance

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent changes the chemical composition parameters of the grease by incorporating specific additives (calcium sulfonate, calcium dinonylnaphthalenesulfonate, organic molybdenum compound, lithium 12-hydroxystearate) in optimized proportions to maintain anti-fretting properties at low temperatures while preserving normal-temperature lubrication performance

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite grease formulation combining multiple thickening agents (calcium sulfonate, calcium dinonylnaphthalenesulfonate, organic molybdenum compound, lithium 12-hydroxystearate) with base oil, where each component contributes specific properties that collectively resolve the low-temperature anti-fretting issue

Inventive Principle:

Principle #40Composite materials

2Reliability

If the viscosity of base oil is increased to improve lubrication, then lubrication performance improves, but grease flowability decreases

Engineering Contradiction:

Improvelubrication performanceVSAvoidgrease flowability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent optimizes the viscosity parameter of the base oil and balances it with the selection and proportioning of thickening agents to achieve a grease composition that maintains both adequate flowability and lubrication performance

Inventive Principle:

Principle #35Parameter changes

3Reliability

If grease flowability is reduced to improve lubrication film formation, then lubrication improves, but rust prevention capability decreases

Engineering Contradiction:

Improvelubrication film formationVSAvoidrust prevention capability

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent formulates a composite grease containing rust preventive additives (calcium sulfonate, calcium dinonylnaphthalenesulfonate) combined with lubricating components, where the synergistic interaction maintains both lubrication film formation and rust prevention capability

Inventive Principle:

Principle #40Composite materials

4Reliability

If aromatic diurea thickener is used to increase grease consistency, then anti-fretting properties improve, but rust prevention and flowability are compromised

Engineering Contradiction:

Improveanti-fretting propertiesVSAvoidrust prevention

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent creates a multi-component composite grease system where aromatic diurea thickener provides anti-fretting properties while calcium sulfonate, calcium dinonylnaphthalenesulfonate, and other additives compensate for and enhance rust prevention, achieving a balanced performance profile

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent adjusts the concentration parameters of each additive component to optimize the balance between anti-fretting properties and rust prevention, ensuring neither function is compromised

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 grease composition effectively reduces fretting wear and exhibits excellent rust prevention even at low temperatures, ensuring the longevity of automotive hub unit bearings by maintaining grease flowability and preventing rust.

Implementation Method 1

a grease composition excellent in the anti-fretting properties at low temperatures and the rust preventing properties

Methodology Applied

Scientific EffectLubrication: Lubrication

Implementation Method 2

diphenyl hydrogen phosphate, and (e) at least one rust preventive selected from the group consisting of sulfonate rust preventives and carboxylic acid rust preventives

Methodology Applied

Scientific EffectRust prevention:

Data Source

PatentUS8895489B2Grease composition for hub unit bearing

Publication Date: 2014.11.25 KYODO YUSHI CO LTD

AI summary

The invention provides a grease composition for hub unit bearing, containing (a) an aromatic diurea thickener, (b) a base oil, (c) a metal salt of oxidized wax, (d) diphenyl hydrogen phosphate, and (e) at least one rust preventive selected from the group consisting of sulfonate rust preventives and carboxylic acid rust preventives. The grease composition of the invention shows excellent anti-fretting properties at low temperature, and at the same time, exhibit excellent rust preventing properties.