Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic -co- compound
Patent
1996-03-04
1997-12-09
Willis, Jr., Prince
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic -co- compound
508486, 508501, C10M13518
Patent
active
056960654
DESCRIPTION:
BRIEF SUMMARY
INDUSTRIAL FIELD OF APPLICATION
This invention relates to an engine oil composition, more specifically, to an engine oil composition which is produced by blending molybdenum dithiocarbamate (hereinafter referred to as "MoDTC") and zinc dithiophosphate containing a primary alkyl group having 8 to 14 carbon atoms (hereinafter referred to as "ZnDTP") to a base oil for an engine oil, which has high residual MoDTC even when the oil degrades, hence providing low friction and low wear over a long period of time, leading to lower fuel consumption. The invention also relates to an engine oil composition which is produced by blending MoDTC, ZnDTP and polyglycerin half ester to a base oil for an engine oil, that is stable under fluid lubricating conditions from extreme pressure conditions and which has an excellent coefficient of friction.
PRIOR ART
Improvements in engine oils have been attempted in the past because of the promotion of energy conservation and technological progresses related to higher performance and higher output from automobiles, but the environment for engine oils has become more severe due to the rise of oil temperatures resulting from higher speeds and higher outputs of engines, deterioration of friction conditions, the limitations on oil capacity due to reductions in weight, the requirements for maintenance-free operation resulting from long drain, etc.
Engine oils play an important role in valve actuating systems, bearings, etc., in addition to their function as a lubricant between pistons and liners. Lubricating conditions differ depending on portions of the engine, and the performance required for engine oils has become diversified. In the piston portion, for example, a fluid lubricating condition is predominant. In this case, a lower viscosity engine oil plays the greatest role in reducing friction loss. When the viscosity of the engine oil is reduced, however, sealability deteriorates and wear increases. In the valve actuating system, on the other hand, lubrication is mainly mixed lubricating and boundary lubricating conditions. Accordingly, because reductions in engine oil viscosity has a negative effect on wear, additives having high extreme-pressure performance and high wear resistance become necessary.
In addition, the regulations on fuel consumption of automobiles and the restrictions on exhaust gases have become more severe due to environmental problems such as the greenhouse effect, emissions of nitrogen oxides (NO.sub.x), etc. For these reasons, further improvements in mechanical efficiency such as from reductions in engine oil viscosity and excellent friction regulating additives are being sought.
As the viscosity of engine oils has been reduced, MoDTC and ZnDTP have been employed so as to reduce frictional loss, to prevent wear and to impart extreme-pressure properties, as additives for the base oil for engine oil. However, when these additives are merely mixed, the resulting engine oil compositions cannot substantially solve such problems as exhaust gas emissions, wear associated with the restrictions on fuel consumption drops in mechanical efficiency resulting from seizure and frictional loss, etc.
MoDTC undergoes deterioration as the oil deteriorates and eventually loses its friction reduction effect. Therefore, how to maintain the performance of MoDTC, particularly in engine oils, has been a critical problem that is yet to be solved. From the aspect of reducing engine oil viscosity or the fuel consumption by friction regulating additives, however, the use of MoDTC is essentially necessary at the present moment. In order to solve such problems as wear, drops in mechanical efficiency due to seizure and frictional loss, etc., therefore, it is necessary to fully exploit the performance of MoDTC, and from the aspect of long drain, too, an oil which maintains the performance of MoDTC even when the oil degrades and which exhibits a friction reduction effect for a long time must be developed.
In connection with ZnDTP, J. A. Spearot, F. Caracciolo et al report in SAE Paper 790941
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Fukushima Aritoshi
Morita Kazuhisa
Saito Yoko
Tanaka Noriyoshi
Tatsumi Yukio
Asahi Denka Kogyo K. K.
Toomer Cephia D.
Willis Jr. Prince
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