Lubricating Oil Composition Using Comb-Shaped Polymer Viscosity Index Improver
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Solution Overview
Problem
Existing lubricating oil compositions for hybrid automobiles face challenges in maintaining low viscosity in low temperature ranges while ensuring sufficient viscosity increase in high temperature ranges to enhance fuel efficiency, wear resistance, and hydraulic characteristics.
Innovation Solution
A lubricating oil composition comprising a mineral oil and an oxygen-containing synthetic oil, blended with a comb-shaped polymer as a viscosity index improver, with a specific content of the oxygen-containing synthetic oil regulated to achieve a kinematic viscosity of 9.3 mm2/s or less at 100° C. and a viscosity index of 280 or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the viscosity of engine oil is reduced to improve fuel efficiency and reduce agitation loss, then the friction coefficient in fluid lubricating parts is reduced, but the evaporation amount increases leading to increased consumption
Solution Approach 1:
The patent uses a composite base oil system combining Group III base oil (80-95 wt%) and Group IV base oil (5-20 wt%) to achieve both low viscosity and low evaporation characteristics. This composite approach allows the lubricating oil to maintain reduced viscosity for fuel efficiency while the Group IV component suppresses evaporation, resolving the contradiction between energy efficiency and substance loss.
2Use of energy by moving object
If the viscosity of engine oil is reduced in low temperature range to improve fuel efficiency, then the agitation loss is reduced, but the wear resistance deteriorates due to insufficient oil film thickness
Solution Approach 1:
The patent employs a viscosity index improver (comb-shaped polymer) that dynamically adjusts the oil's viscosity based on temperature. At low temperatures (40°C), the viscosity is reduced to 7.5-12.5 mm²/s for fuel efficiency, while at high temperatures (100°C), the viscosity increases to 2.0-4.0 cSt to maintain adequate oil film thickness and wear protection. This dynamic adaptation resolves the contradiction between fuel efficiency and wear resistance.
3Quantity of substance
If a viscosity index improver is added to increase the viscosity index, then the viscosity in low temperature range increases, but the evaporation amount increases requiring use of synthetic oil with low viscosity
Solution Approach 1:
The patent changes the chemical composition parameters by selecting specific base oils with appropriate viscosity indices and evaporation characteristics. The Group III base oil provides a viscosity index of 90-110, while the Group IV base oil contributes to both viscosity index enhancement and evaporation suppression. This parameter optimization allows achieving high viscosity index without excessive evaporation, resolving the contradiction between quantity of substance and loss of substance.
4Reliability
If the viscosity of engine oil is increased in high temperature range to improve wear resistance, then the oil film thickness is maintained, but the fuel efficiency deteriorates due to increased agitation loss
Solution Approach 1:
The viscosity index improver creates a dynamic viscosity-temperature relationship where the oil maintains low viscosity at operating temperatures (40°C: 7.5-12.5 mm²/s) for fuel efficiency, while providing sufficient viscosity at high temperatures (100°C: 2.0-4.0 cSt) for wear protection. This dynamic behavior resolves the contradiction between wear resistance and fuel efficiency by adapting viscosity to operational conditions.
Data Source
AI summary
A lubricating oil composition that is hard to increase in viscosity in the low temperature range and is easy to increase in viscosity in the high temperature range. The lubricating oil composition contains a base oil and a viscosity index improver. The base oil contains a mineral oil and an oxygen-containing synthetic oil. The viscosity index improver contains a comb-shaped polymer. The lubricating oil composition has a kinematic viscosity of 100° C. of 9.3 mm2/s or less, a viscosity index of 280 or more, and a content Y (% by mass) of the oxygen-containing synthetic oil based on the total amount of the lubricating oil composition satisfying the following expression (1): α≤Y<−3.7 ln(X)+β (1), where α=0.5, β=19, and X represents a ratio of the number of carbon atoms and the number of oxygen atoms per one molecule of the oxygen-containing synthetic oil.