Diesel Lubricant Formulation for Extended Drain Interval

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Solution Overview

Problem

Lubricant formulations for diesel engines, particularly medium speed diesel engines, have a short drain interval due to copper corrosion products that catalyze oxidation, leading to premature degradation of oil components and reduced service life.

Innovation Solution

A lubricant composition comprising an alkali or alkaline earth metal sulfonate detergent, an alkali or alkaline earth metal phenate detergent, and specific antioxidants like hindered phenolic derivatives, which maintains a high total base number (TBN) and is devoid of zinc dialkyldithiophosphate compounds, reducing oxidation and corrosion even in the presence of copper corrosion products.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional oxidation inhibitors are added to the lubricant, then oxidation of oil components is prevented, but the lubricant service life is significantly shortened due to copper catalyzed oxidation

Engineering Contradiction:

Improveoxidation preventionVSAvoidlubricant service life

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the chemical parameters of the oxidation inhibitor system by using a synergistic combination of calcium phenate detergent (providing high TBN) and hindered phenolic antioxidants (BHT and BHA), replacing conventional single-agent oxidation inhibitors. This parameter change enables the lubricant to resist copper-catalyzed oxidation for extended periods while maintaining TBN above 3 mg KOH/g for over 184 days of service.

Inventive Principle:

Principle #35Parameter changes

2Loss of time

If the drain interval is extended, then maintenance costs are reduced, but copper corrosion products accumulate to catalyze oxidation and degrade the lubricant

Engineering Contradiction:

Improvedrain intervalVSAvoidcopper catalyzed oxidation

Core Design Contradiction:

Loss of timeVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of copper corrosion products into a manageable condition by using calcium phenate detergent which maintains high TBN levels that neutralize copper-catalyzed oxidation. The high TBN calcium phenate acts as a buffer that prevents copper ions from catalyzing rapid oxidation, allowing extended drain intervals even in the presence of copper corrosion products from engine oil coolers.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent uses a composite antioxidant system combining calcium phenate detergent with hindered phenolic antioxidants (BHT and BHA) in specific proportions. This composite formulation provides synergistic protection where the calcium phenate maintains TBN and the hindered phenolics provide additional oxidation resistance, enabling extended service life despite copper contamination.

Inventive Principle:

Principle #40Composite materials

3Reliability

If zinc dialkyldithiophosphate compounds are used, then corrosion protection is provided, but the lubricant cannot maintain high TBN for extended periods in the presence of copper

Engineering Contradiction:

Improvecorrosion protectionVSAvoidTBN retention period

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent extracts zinc dialkyldithiophosphate compounds from the lubricant formulation and replaces them with calcium phenate detergent and hindered phenolic antioxidants. This removal eliminates the limitation on TBN retention while maintaining corrosion protection through the high TBN calcium phenate system, enabling service life extension beyond 184 days.

Inventive Principle:

Principle #2Taking out (Extraction)

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 lubricant composition significantly extends the drain interval by maintaining a high TBN and reducing acid growth, resulting in a 50% increase in service life and reduced maintenance costs, while providing enhanced protection against oxidation and corrosion.

Implementation Method 1

the lubricant composition comprises an alkali or alkaline earth metal sulfonate detergent, an alkali or alkaline earth metal phenate detergent, and at least one antioxidant selected from the group consisting essentially of hindered phenolic derivatives of C3 to C6 acids and C7 to C9 esters of hindered phenolic derivatives of C3 to C6 acids

Methodology Applied

Scientific EffectOxidation inhibition: Oxidation

Implementation Method 2

maintaining a high total base number (TBN) and reducing acid growth

Methodology Applied

Scientific EffectNeutralization:

Data Source

PatentUS8377856B2Extended drain diesel lubricant formulations

Publication Date: 2013.02.19 AFTON CHEMICAL CORPORATION

AI summary

A method for maintaining a total base number (TBN) above about 3 mg KOH/g for a lubricant for a diesel engine for greater than about 184 days. The method includes supplying as the lubricant, a lubricant composition comprising a sulfonate detergent having a TBN ranging from about 20 to about 100 and a phenate detergent having a TBN ranging from about 200 to about 350 and an antioxidant selected from the group consisting essentially of hindered phenolic derivatives of C3 to C6 acids and C7 to C9 esters of hindered phenolic derivatives of C3 to C6 acids. The phenate detergent is present in an amount that is greater than 15 percent by weight of the total weight of detergents in the lubricant composition and the lubricant composition is substantially devoid of zinc dialkydithiophosphate compounds and has a sulfated ash content of less than 1.0 wt. %.