Refrigerator Lubricating Oil Composition for CO2 Systems

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Solution Overview

Problem

Refrigerator oils used with carbon dioxide as a refrigerant face challenges in maintaining lubrication capability, especially under high-temperature and high-speed conditions in compressors, and the deposition of friction modifiers at low temperatures.

Innovation Solution

A lubricating oil composition blending polyoxyalkylene glycol (PAG) base oil with a specific alcohol and an amidoamine compound, which enhances lubrication capability while preventing the deposition of the friction modifier at low temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a friction modifier is added to enhance lubrication capability in high-temperature and high-speed conditions, then lubrication performance is improved, but deposition occurs at low temperatures

Engineering Contradiction:

Improvelubrication capabilityVSAvoiddeposition of friction modifier

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical parameters of the friction modifier by selecting specific compounds (alkyl succinimides with C12-C20 alkyl groups, alkylamines with C12-C20 alkyl groups, or their reaction products) that maintain solubility across a wide temperature range. This parameter selection ensures the friction modifier remains effective at high temperatures while preventing low-temperature deposition.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite material principles by combining the friction modifier with a polyolester base oil and optionally a polyalphaolefin in specific proportions. This composite formulation creates a lubricating oil composition where the base oil and friction modifier work synergistically to provide both high-temperature lubrication and low-temperature fluidity without deposition.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If polyoxyalkylene glycol is used as base oil for carbon dioxide refrigerant compatibility, then refrigerant compatibility is improved, but lubrication capability under high-temperature and high-speed conditions is insufficient

Engineering Contradiction:

Improverefrigerant compatibilityVSAvoidlubrication capability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent merges two different base oil types - polyolester (which provides excellent lubrication capability under high-temperature and high-speed conditions) and polyalphaolefin (which provides good refrigerant compatibility and low-temperature fluidity). This combination allows the lubricating oil to simultaneously achieve both refrigerant compatibility and sufficient lubrication capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The friction modifier acts as an intermediary that enhances the lubrication capability of the base oil composition. By adding specific friction modifiers (alkyl succinimides, alkylamines, or their reaction products), the patent compensates for the insufficient lubrication capability of polyolester/polyalphaolefin blends, achieving both refrigerant compatibility and high lubrication performance.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP3378925B1Composition for refrigerator and refrigerator containing same

Publication Date: 2022.09.07 IDEMITSU KOSAN CO LTD

AI summary

The lubricating oil composition for a refrigerator of the present invention is used with a refrigerant containing carbon dioxide, and contains a base oil (A) containing a polyoxyalkylene glycol as a major component, and an alcohol (B) having at least one hydroxy group, in which a total number of the hydroxy group and an ether bond is from 2 to 3 (provided that the number of an ether bond may be 0).