Lubrication oil composition

Abstract

The present invention provides a lubricating oil composition having an extremely high viscosity index and a low coefficient of traction as a low coefficient of fluid friction in an elastohydrodynamic lubrication which is excellent in saving of energy and reduction in fuel consumption. The lubricating oil composition according to the present invention includes the following components (A) and (B): (A) a low-viscosity synthetic oil comprising a compound containing ether bond(s) in a molecule thereof and having a kinematic viscosity of less than 10 mm²/s as measured at 40° C., in which a ratio of the number of oxygen atoms to the number of carbon atoms as constituents of the compound (O/C ratio) and the kinematic viscosity (mm²/s) of the compound as measured at 40° C. satisfy the following formula (1); Kinematic Viscosity at 40° C.≦12−[(O/C ratio)×30] (1); and (B) a high-viscosity synthetic oil as a hydrocarbon-based synthetic oil having a kinematic viscosity of 40 mm²/s or more as measured at 100° C. which includes at least one compound selected from the group consisting of an α-olefin oligomer, a hydrogenated α-olefin oligomer and an ethylene-propylene co-oligomer.

Description

TECHNICAL FIELD[0001]The present invention relates to a lubricating oil composition, and more particularly, to a lubricating oil composition having a high viscosity index and a low coefficient of fluid friction in an elastohydrodynamic lubrication which is excellent in saving of energy and reduction in fuel consumption.BACKGROUND ART[0002]Lubricating oils have been inherently used for the purpose of reducing friction at sliding portions by forming an oil film on the sliding portions. Therefore, in order to form a strong oil film, it is advantageous that the lubricating oils have a high viscosity. However, the lubricating oils having a high viscosity require a considerable amount of power upon stirring or supply thereof and therefore suffer from a large energy loss, thereby failing to achieve saving of energy and improvement in fuel consumption. In consequence, in recent years, reduction in viscosity of the lubricating oils has proceeded to prevent occurrence of a power loss.[0003]Ho...

AI Technical Summary

Benefits of technology

[0024]In accordance with the present invention, it is possible to provide a lubricating oil composition having an extremely high viscosity index and a low coefficient of traction as a coefficient of fluid friction in an elastohydrodynamic lubrication which is excellent in saving of energy and reduction in fuel consumption. Therefore, it is also possible to provide a lubricating oil composition capable of reducing a power loss in mechanical devices including rolling bearings or gears which is excellent in saving of energy and reduction in fuel consumption.

[0025]The lubricating oil composition according to present invention includes (A) a low-viscosity synthetic oil and (B) a high-viscosity synthetic oil.

[0026]The low-viscosity synthetic oil used as the component A in the present invention is required to be in the form of a compound containing ether bond(s) in a molecule thereof. The compound may contain at least one ether bond in a molecule thereof, and may also contain two or more ether bonds in a molecule thereof. The number of ether bonds contained in a molecule of the compound is preferably from 1 to 6, more preferably from 1 to 4 and still more preferably from 3 to 4.

[0027]The compound containing e

Problems solved by technology

However, the lubricating oils having a high viscosity require a considerable amount of power upon stirring or supply thereof and therefore suffer from a large energy loss, thereby failing to achieve saving of energy and improvement in fuel consumption.

However, if the viscosity of the lubricating oils is excessively reduced, it becomes difficult to form an oil film on sliding portions when exposed to a high temperature.

As a result, there tend to occur increas