Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic compound containing boron
Patent
1997-09-15
1999-10-12
McAvoy, Ellen M.
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic compound containing boron
508479, 508480, 508501, 508502, 508503, C10M14112
Patent
active
059654953
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a lubricating oil composition for internal combustion engines, more particularly, to lubricating oil composition which has a low ash content, does not show adverse effects on the performance of apparatuses for exhaust gas treatment, and exhibits excellent resistance to coking and oxidation stability, and still more particularly, to a lubricating oil composition advantageously used for Diesel engines and gas engine heat pumps (GHP).
BACKGROUND ART
In recent years, environmental pollution caused by nitrogen oxides (NO.sub.x gases) and particulate materials (PM) which are discharged from internal combustion engines, particularly Diesel engines, is an important problem, and decreasing nitrogen oxides and particulate materials in exhaust gas is urgently required.
For overcoming the problem, exhaust gas recirculation (EGR) and lowering of the peak temperature of combustion by delaying time of fuel injection are examined for decreasing NO.sub.x gases.
However, when the peak temperature of combustion is lowered, black smoke and PM are increased, and attaching an apparatus for exhaust gas treatment becomes necessary. As the apparatus for exhaust gas treatment, PM traps or oxidation catalysts are examined. Because these apparatuses have a structure of a filter, clogging by metal components in oil causes a problem when conventional Diesel engine oil is used.
In lubricating oil compositions for internal combustion engines, an ashless dispersant and a metallic detergent are generally contained as the essential components. However, decrease in metallic components is desired because of the problem of clogging, as described above. This causes another problem in that excellent effects of keeping an engine clean and preventing formation of deposit become difficult to be obtained when metallic detergent is not used or used in a small amount.
DISCLOSURE OF THE INVENTION
Under the above circumstances, the present invention has an object of providing a lubricating oil composition for internal combustion engines which has a small ash content, does not show adverse effect on the performance of apparatuses for exhaust gas treatment, such as oxidation catalysts and PM traps, and moreover, exhibits excellent resistance to coking and oxidation stability.
As the result of extensive studies conducted by the present inventors to develop a lubricating oil composition for internal combustion engines having the above desirable properties, it was discovered that resistance to coking and oxidation stability are improved when a lubricating oil composition comprises a metallic detergent in an amount smaller than that in conventional compositions and an ashless dispersant containing boron in a specific amount or more relative to the amount of the metallic dispersant, and that these properties are further improved when a lubricating oil composition additionally comprises an ester of an aromatic carboxylic acid having hydroxyl group and a hydroxy compound or a compound containing boron which is derived from the ester. The present invention has been completed on the basis of the discovery.
Accordingly, the present invention provides a lubricating oil composition for internal combustion engines which comprises a base oil, (a) an ashless dispersant containing boron, (b) a metallic detergent, and optionally (c) at least one selected from a group consisting of esters of aromatic carboxylic acids having hydroxyl group and hydroxy compounds and compounds containing boron which are derived from the esters, wherein a ratio [B]/[M] of a content of boron [B] in the composition in % by weight to a total content of metals [M] derived from the detergent in the composition in % by weight is not less than 0.15, and a sulfated ash content in the composition is not more than 1.5% by weight.
THE MOST PREFERRED EMBODIMENT TO CARRY OUT THE INVENTION
As the base oil in the lubricating oil of the present invention, mineral oil or synthetic oil is generally used. The type and the properties of the mineral oil an
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Goto Masahisa
Miyaji Tomomi
Idemitsu Kosan Co. Ltd.
McAvoy Ellen M.
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