Overbased Calcium-Magnesium Lubricants for LSPI Reduction
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Solution Overview
Problem
Boosted internal combustion engines experience low-speed pre-ignition (LSPI) events, which are difficult to identify and suppress due to their sporadic and uncontrolled nature, leading to engine degradation and potential damage, and existing solutions either fail to effectively reduce LSPI or compromise anticorrosive effects.
Innovation Solution
A lubricating oil composition comprising greater than 50 wt.% base oil, overbased calcium and magnesium detergents with specific ratios and amounts, and molybdenum compounds, along with boron, to reduce LSPI events by 60% while maintaining anticorrosive properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the total amount of detergent is reduced to reduce LSPI events, then LSPI events are reduced, but anticorrosive effect is compromised
Solution Approach 1:
The patent changes the parameters of the detergent by using overbased detergents with specific total base numbers (greater than 225 mg KOH/g for both calcium and magnesium detergents) and specific metal ratios. This allows reducing the total detergent amount while maintaining sufficient anticorrosive protection through the optimized base number and metal composition.
Solution Approach 2:
The patent employs a composite detergent system combining overbased calcium detergent and overbased magnesium detergent in a specific ratio (Ca:Mg metal ratio of 1:0.05 to 1:5). This composite approach provides both LSPI reduction and anticorrosive protection that neither detergent could achieve alone at reduced concentrations.
2Object-affected harmful factors
If overbased calcium and magnesium detergents are used with specific ratios to reduce LSPI, then LSPI events are reduced by 60%, but the complexity of additive composition increases
Solution Approach 1:
The patent defines specific parameter ranges for the detergent components (total base number >225 mg KOH/g, Ca:Mg ratio of 1:0.05 to 1:5, specific metal concentrations) that simplify the formulation process by providing clear guidelines for achieving LSPI reduction without requiring complex optimization of multiple variables.
3Productivity
If detergent amount is reduced to suppress LSPI, then LSPI events decrease, but engine protection capability is compromised
Solution Approach 1:
The patent optimizes the total base number parameter to greater than 225 mg KOH/g for both calcium and magnesium overbased detergents, which provides sufficient neutralizing capacity and protective film formation even at reduced detergent concentrations, thereby maintaining engine protection capability while improving LSPI suppression.
Solution Approach 2:
The synergistic combination of overbased calcium and magnesium detergents in specific ratios creates a composite protective system that enhances both LSPI suppression and engine protection capability, allowing reduced total detergent amounts while maintaining comprehensive engine protection.
Data Source
AI summary
A lubricating oil composition and method of operating a boosted internal combustion engine. The lubricating oil includes greater than 50 wt.% of a base oil, one or more overbased calcium-containing detergents, one or more overbased magnesium-containing detergents and one or more molybdenum compounds and leads to a more than 60% reduction in LSPI compared to the LSPI of a reference oil and passes the Ball Rust Test. The ratio of wt% calcium from the overbased detergents to wt.% of magnesium from the overbased detergents is less than 11.9. A ratio of total ppm of magnesium to total TBN of the lubricating oil in mg KOH/g is greater than 19. A ratio of the total ppm of calcium to the total TBN of the lubricating oil is less than 222. The oil and method may reduce low-speed pre-ignition events in a boosted internal combustion relative to commercially available lubricating oils.