Lubricant oil composition

Abstract

Provided is a lubricating oil composition favorable for reducing friction in a sliding mechanism equipped with a piston ring and a liner, in a device having the sliding mechanism. The lubricating oil composition contains a lubricant base oil, (1) a polymethacrylate and / or an olefin copolymer having a mass-average molecular weight of 100,000 to 600,000, and (2) an ester-type ashless friction modifier and / or an amine-type ashless friction modifier, and has a shear viscosity at 150° C. of 2.3 mPa· or more and less than 3.7 mPa·s.

Description

TECHNICAL FIELD[0001]The present invention relates to a lubricating oil composition, in particular to a lubricating oil composition favorable for reducing friction in a device equipped with a piston ring and a liner, especially to a lubricating oil composition for internal combustion engines with improved fuel-saving performance.BACKGROUND ART[0002]From the viewpoint of environmental load reduction, it is desired to reduce CO2 to be emitted by automobiles for suppressing global warming, and it is desired to improve further fuel-saving performance of lubricating oil for internal combustion engines of automobiles, etc. For improving fuel-saving performance of lubricating oil for internal combustion engines, improvement and viscosity reduction in point of composition of lubricating oil are being under way in the region of fluid lubrication (for example, PTLs 1 and 2). However, mere lubricating oil viscosity reduction is problematic in point of lubrication insufficiency (friction increa...

AI Technical Summary

Benefits of technology

The invention provides a lubricating oil that reduces friction in devices with a piston ring and liner sliding mechanism. This helps to improve the performance of the device.

Problems solved by technology

However, mere lubricating oil viscosity reduction is problematic in point of lubrication insufficiency (friction increase) in a severe lubrication environment such as sliding between a piston ring and a liner, and therefore, optimal technique for formulating a lubricating oil is further desired.

On the other hand, from the viewpoint of improvement of fuel efficiency of engines, down-sized lightweight high-power engines are being popular, but also in this case, there still exist concerns about insufficient lubricity between a piston ring and a liner with increase in thermal load.

PTL 3 tries to attain friction reduction and an excellent fuel-saving effect from the viewpoint of both materials of a piston ring of an engine and a lubricating oil, but even with such a lubricating oil, the lubricity between a piston ring and a liner is still insufficient.

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