Transmission Lubricating Oil Composition for Hybrid Vehicles

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Solution Overview

Problem

Existing lubricating oil compositions for transmissions fail to simultaneously satisfy gear properties, clutch properties, cooling properties, and electric insulating properties, which are essential for modern vehicle applications such as hybrid and electric cars.

Innovation Solution

A lubricating oil composition is developed by blending a base oil with a viscosity index improver having a mass average molecular weight of 10,000 to 50,000 and a polyamide and/or polyol ester, where the base oil includes a synthetic oil with a kinematic viscosity of 1.0 to 10.0 mm2/s at 100°C, optimizing gear, clutch, cooling, and insulating properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional lubricating oil compositions are used, then gear properties or clutch properties can be satisfied, but it is impossible to simultaneously satisfy gear properties, clutch properties, cooling properties, and electric insulating properties

Engineering Contradiction:
Improvemulti-functionality (gear, clutch, cooling, insulating properties)VSAvoidperformance stability across multiple functions
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies multi-functionality by designing a lubricating oil composition that simultaneously performs four distinct functions: gear lubrication (using synthetic oil base with appropriate viscosity), clutch operation (using polyamide and polyol ester additives for friction control), cooling (achieving through high thermal conductivity of the base oil), and electric insulation (maintaining high insulating properties). This single composition replaces what would traditionally require multiple separate fluids, directly resolving the technical contradiction between versatility and reliability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent employs composite materials by combining multiple chemical components in specific proportions: synthetic oil (A-1) as the base, viscosity index improver (B), polyamide (C-1), and polyol ester (C-2). This composite formulation integrates the beneficial properties of each component to achieve simultaneous gear protection, clutch performance, cooling efficiency, and electrical insulation, thereby resolving the contradiction between multi-functionality and performance stability.

Inventive Principle:
Principle #40Composite materials

2Adaptability or versatility

If the lubricating oil composition is designed for high insulating properties and cooling properties, then it can be used for motor cooling, but gear properties and clutch properties may be compromised

Engineering Contradiction:
Improvecombined use for transmission and motor coolingVSAvoidgear properties (seizure resistance, shear stability)
Core Design Contradiction:
Adaptability or versatilityVSStrength

Solution Approach 1:

The patent applies local quality by assigning specific functional roles to different components within the lubricating oil composition. The synthetic oil base (A-1) with controlled viscosity provides gear lubrication and cooling, while the polyamide (C-1) and polyol ester (C-2) additives are specifically positioned to provide clutch friction control and insulating properties. This differentiated component assignment allows the single composition to simultaneously satisfy gear strength requirements and motor cooling/insulation requirements without compromise.

Inventive Principle:
Principle #3Local quality

3Stability of the object's composition

If a viscosity index improver with mass average molecular weight of 10,000 to 50,000 is used, then viscosity stability across temperature ranges is improved, but the complexity of the composition increases

Engineering Contradiction:
Improveviscosity stability across temperature rangeVSAvoidcomposition complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by precisely controlling the molecular weight parameter of the viscosity index improver (B) within the range of 10,000 to 50,000. This specific parameter range optimizes the balance between viscosity stability across temperature ranges and compositional simplicity. The controlled molecular weight ensures adequate viscosity modification without excessive complexity, resolving the contradiction between composition stability and device complexity.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS10889779B2Transmission lubricating oil composition
Publication Date: 2021.01.12 IDEMITSU KOSAN CO LTD

AI summary

Provided is a lubricating oil composition for a transmission having excellent gear properties, clutch properties, cooling properties, and electric insulating properties. The lubricating oil composition for a transmission preparing by blending (A) a base oil, (B) a viscosity index improver having a mass average molecular weight of 10,000 to 50,000, and (C-1) a polyamide and/or (C-2) a polyol ester, the base oil (A) including (A-1) a synthetic oil having a kinematic viscosity at 100° C. of 1.0 to 10.0 mm2/s.