Low-HTHS Engine Lubricant Composition for Fuel Economy and LSPI Mitigation
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Solution Overview
Problem
Current lubricating formulations for internal combustion engines fail to meet the stringent requirements of improving fuel economy, cleanliness, TBN retention, and reducing low-speed preignition (LSPI) while maintaining durability, as specified by API SN plus and ILSAC GF-6 for passenger car motor oils and API CK-4 for heavy duty diesel engines.
Innovation Solution
A lubricating composition comprising at least 50% Group IV base oil, boron-containing and boron-free polyisobutenyl succinimide dispersants, overbased magnesium and calcium detergents, and an ashless friction modifier, with a High Temperature High Shear viscosity of less than 2.5 mPa·s, to enhance performance in fuel economy, cleanliness, and reduce corrosion and oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lubricating formulations are used, then basic engine protection is provided, but fuel economy improvement, cleanliness, TBN retention, and LSPI mitigation are insufficient
Solution Approach 1:
The patent modifies the chemical composition parameters by using Group IV base oil (at least 50 wt%) instead of conventional base oils, and by specifying precise ranges for additives including boron-containing dispersant (0.1-2.0 wt%), boron-free dispersant (0.1-2.0 wt%), overbased magnesium detergent (0.1-1.0 wt%), overbased calcium detergent (0.1-0.5 wt%), and ashless friction modifier (0.1-0.5 wt%). These parameter changes achieve HTHS viscosity of 2.0-2.5 mPa·s at 100°C, which optimizes both fuel economy and engine protection.
Solution Approach 2:
The patent creates a composite lubricating composition by combining multiple functional additives with specific base oil. The composition integrates boron-containing polyisobutenyl succinimide dispersant, boron-free dispersant, overbased magnesium detergent, overbased calcium detergent, and ashless friction modifier together in optimized proportions. This composite approach synergistically improves fuel economy, cleanliness, TBN retention, and LSPI mitigation while maintaining engine durability.
2Reliability
If higher viscosity lubricants are used to improve wear protection, then engine durability improves, but fuel economy deteriorates
Solution Approach 1:
The patent precisely controls the HTHS viscosity parameter to range from 2.0 to 2.5 mPa·s at 100°C by adjusting base oil selection (Group IV with at least 50 wt%) and additive package composition. This optimized viscosity range provides sufficient wear protection while minimizing viscous drag and improving fuel economy, resolving the traditional trade-off between protection and energy efficiency.
Solution Approach 2:
The patent uses ashless friction modifiers that replicate the protective function of traditional high-viscosity lubricants through chemical film formation rather than relying solely on physical viscosity. The ashless friction modifier (0.1-0.5 wt%) creates protective tribofilms on metal surfaces, providing wear protection without the energy penalty of high viscosity conventional lubricants.
3Reliability
If detergents and dispersants are increased to improve cleanliness and TBN retention, then engine cleanliness improves, but ash content increases causing deposit formation
Solution Approach 1:
The patent optimizes the balance between detergent/dispersant concentration and ash content by specifying overbased magnesium detergent (0.1-1.0 wt%) and overbased calcium detergent (0.1-0.5 wt%) within controlled ranges. The boron-containing dispersant (0.1-2.0 wt%) and boron-free dispersant (0.1-2.0 wt%) work synergistically to maintain engine cleanliness while controlling total ash content to prevent excessive deposit formation.
Solution Approach 2:
The patent introduces boron-containing polyisobutenyl succinimide dispersant as an intermediary substance that enhances the effectiveness of detergents and dispersants. This boron-containing additive (0.1-2.0 wt%) improves cleanliness and TBN retention while working with the overbased detergents to control ash content and prevent deposit formation, acting as a mediator between cleanliness improvement and deposit prevention.
Data Source
AI summary
The instant disclosure generally relates to lubricating compositions having an oil of lubricating viscosity, a boron-containing additive, a boron-free dispersant, an overbased magnesium-based detergent, an overbased calcium-based detergent, an ashless friction modifier, and, optionally, other performance additives. The instant lubricating composition has a High Temperature High Shear (HTHS) viscosity according to ASTM D4683 of less than 2.7 mPa s. The instant lubricating compositions disclosed herein may accomplish one or more of the following improve fuel economy, reduce corrosion, reduce oxidation, improve cleanliness, and improve wear performance of an internal combustion engine.