Nanoparticle Lubricating Oil for Cooling and Electrical Insulation

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Solution Overview

Problem

Existing lubricating oil compositions for electric vehicles and hybrid vehicles fail to balance excellent cooling performance with electrical insulation properties, leading to reliability issues.

Innovation Solution

A lubricating oil composition containing specific amounts of solid particles with an average primary particle diameter of 500 nm or less and a dispersant, with a mass content of 0.1 to 30% and 0.1 to 20% respectively, along with a mass ratio of 0.05 to 3, enhances both cooling and insulation properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If existing ATF or CVTF is used for cooling electric motors, then cooling performance is achieved, but electrical insulation properties deteriorate leading to reliability issues

Engineering Contradiction:
Improvecooling performanceVSAvoidelectrical insulation properties
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The invention uses a composite lubricating oil composition combining base oil, solid particles (500 nm or less), and dispersant. This composite structure allows the solid particles to enhance cooling performance while the dispersant maintains electrical insulation properties, resolving the contradiction between cooling efficiency and insulation reliability

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention changes the physical parameters of the lubricating oil by incorporating solid particles with specific size (500 nm or less) and controlled content (0.1-30 mass%). This parameter optimization enables improved thermal conductivity for better cooling while maintaining appropriate viscosity and insulation characteristics

Inventive Principle:
Principle #35Parameter changes

2Temperature

If solid particles are added to enhance cooling performance, then cooling ability improves, but viscosity may increase affecting flow characteristics

Engineering Contradiction:
Improvecooling performanceVSAvoidviscosity
Core Design Contradiction:
TemperatureVSUse of energy by moving object

Solution Approach 1:

The invention applies local quality by using solid particles with very small size (500 nm or less). These fine particles provide thermal conductivity benefits for cooling while their small size prevents significant increase in bulk viscosity, allowing the system to gain thermal performance without substantial penalty in flow characteristics

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The solid particles function similarly to porous structures by providing thermal pathways through the lubricating oil without creating continuous solid networks that would dramatically increase viscosity. The dispersed particulate structure enables heat transfer enhancement while maintaining fluidity

Inventive Principle:
Principle #31Porous materials

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 composition achieves low viscosity and high insulation, making it suitable for cooling electrical apparatuses with improved reliability.

Implementation Method 1

a dispersant (C)... wherein a content of the solid particles (B) is 0.1 to 30 mass % based on a total amount of the lubricating oil composition, and a content of the dispersant (C) is 0.1 to 20 mass % based on the total amount of the lubricating oil composition

Methodology Applied
Scientific EffectAdsorption: Adsorption

Data Source

PatentUS20260062639A1Lubricating oil composition
Publication Date: 2026.03.05 IDEMITSU KOSAN CO LTD

AI summary

There has been a demand for a lubricating oil composition that has excellent cooling performance and insulating properties. This lubricating oil composition contains a base oil (A), solid particles (B) that have an average primary particle diameter of 500 nm or less, and a dispersant (C); the content of the solid particles (B) is 0.1 to 30% by mass based on the total amount of the lubricating oil composition; and the content of the dispersant (C) is 0.1 to 20% by mass based on the total amount of the lubricating oil composition.