Low Molecular Weight Silicon Compounds for Engine Oil LSPI and Aeration
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Solution Overview
Problem
Existing lubricating compositions face challenges in achieving low aeration and foaming while maintaining acceptable low-speed pre-ignition performance, particularly due to the detrimental effects of silicon-containing compounds on foaming and aeration tests.
Innovation Solution
A lubricating composition for spark-ignition engines, specifically a passenger car motor oil, is formulated with one or more base oils of lubricating viscosity, about 15 ppm or less of silicon from a polydialkylsiloxane antifoam polymer, and at least 100 ppm of additional silicon from silicon-containing compounds like siloxane or silane derivatives, with a molecular weight of no more than 650, to maintain low foam and aeration while ensuring passing LSPI performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If silicon-containing compounds are added to improve anti-foaming performance, then foaming is reduced, but aeration performance deteriorates
Solution Approach 1:
The patent changes the molecular weight parameter of silicon-containing compounds from conventional high molecular weight to low molecular weight (≤650 g/mol), which fundamentally alters how the silicon compounds interact with the lubricant system. This parameter change allows the silicon compounds to provide anti-foaming action while avoiding the detrimental aeration effects associated with higher molecular weight silicons
Solution Approach 2:
The patent creates a composite additive package combining low molecular weight silicon-containing compounds with other lubricant additives in specific concentrations. This composite approach allows the silicon compounds to work synergistically with other additives to achieve both anti-foaming and acceptable aeration performance simultaneously
2Object-generated harmful factors
If silicon-containing compounds are added to reduce foaming, then foam stability improves, but low-speed pre-ignition performance deteriorates
Solution Approach 1:
By restricting the molecular weight of silicon-containing compounds to 650 g/mol or less, the patent fundamentally changes the performance characteristics. Low molecular weight silicons provide sufficient anti-foaming action while avoiding the LSPI promotion effect observed with conventional high molecular weight silicons
Solution Approach 2:
The patent applies silicon-containing compounds at specific, controlled concentrations (1-100 ppm) rather than using high concentrations of high molecular weight silicons. This localized application at optimal concentrations achieves foam control without the detrimental LSPI effects
3Object-generated harmful factors
If high molecular weight polydimethylsiloxane polymers are used, then anti-foaming performance improves, but aeration and foaming tests show detrimental effects
Solution Approach 1:
The patent inverts the conventional approach by using low molecular weight silicon-containing compounds (≤650 g/mol) instead of high molecular weight polydimethylsiloxane polymers. This parameter inversion fundamentally changes the interaction with the lubricant system, providing anti-foaming action while passing aeration tests
Solution Approach 2:
The patent employs low molecular weight silicon-containing compounds that can be effectively used at very low concentrations (1-100 ppm). These low molecular weight compounds provide sufficient anti-foaming action without the persistent detrimental effects associated with high molecular weight polymers
Data Source
AI summary
The present disclosure relates to lubricating compositions and methods of lubricating a spark-ignition engine effective to depress low-speed pre-ignition (LSPI) events and to maintain low foaming and/or aeration through selected silicon chemistries and treat rates.