Compositions – Heat-exchange – low-freezing or pour point – or high boiling... – Organic components
Patent
1988-02-04
1989-12-26
Lieberman, Paul
Compositions
Heat-exchange, low-freezing or pour point, or high boiling...
Organic components
585 20, 585436, 208 14, C10M10504
Patent
active
048896497
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to an improved method for transmitting power using a traction drive fluid composition having a high viscosity and an excellent traction coefficient. More particularly, the invention relates to a method for transmitting power in which a composition comprising a mixture of hydrocarbons represented by specific chemical formulae is employed.
The method for transmitting power with traction drive is the one in which power is transmitted by shearing stress caused by an oil film of a traction drive fluid that is formed between rotating bodies (revolving bodies) which are rotating in relative relationship. This method is applied to traction drive devices such as transmission devices and change gears, for example, automatic transmission gears for automobiles, variable speed transmission devices and hydraulic torque converters. As for the traction drive fluids used for these devices, a high traction coefficient is required.
BACKGROUND ART
There are hitherto proposed a large number of compounds as traction drive fluids. For example, proposed in U.S. Pat. No. 3,652,418, etc., are decalin, perhydroanthracene, polycyclohexyl compounds, bicyclohexyl compounds, dicyclohexyl compounds, hydrogenation products of .alpha.-methylstyrene dimers, adamantanes, alkylbenzenes and hydrogenation products of styrenated cumene.
With the development in automobile technology in recent years, the sizes of the above-mentioned traction drive devices have been reduced, while they are used under severer conditions of higher speed and higher load. Accordingly, the use conditions for the traction drive fluids in these devices have become severer at higher temperatures.
Among the foregoing hitherto proposed compounds, however, those put into practice are not many because of their impractical traction coefficients and the difficulty of obtaining the raw materials for industrial-scale production. Only 2,4-dicyclohexyl-2-methylpentane proposed in U.S. Pat. No. 3,994,816 can be exemplified as a material that is acceptable for practical uses.
In the traction drive devices, as power is transmitted by the shearing stress caused by an oil film of a traction drive fluid that is formed between rotating bodies (revolving bodies) which are rotating in relative relationship, the thickness of the film must be maintained to a certain value. Accordingly, a viscosity to a certain level is required even in high temperature conditions. By this fact, high viscosity fluids are required recently. In addition, not only the viscosity but also a high traction coefficient is also necessary, of course.
Meanwhile, even in the case of the typical compound of 2,4-dicyclohexyl-2-methylpentane among those barely put into practice, the viscosity is not always satisfactory though the traction coefficient is high to some extent. In other words, the viscosity (at 100.degree. C.) of this compound itself is only 3.6 cSt (10.sup.-2 cm.sup.2 /sec). Therefore, it was proposed to add a viscosity index improving agent such as polymethacrylate and polyisobutylene in order to raise the viscosity. These viscosity index improving agent can raise the viscosity indeed, however, the traction coefficient is lowered to make the matter worse. In addition, when a traction drive fluid is used for a long period of time under severe conditions, undesirable results are often caused to occur that the viscosity is lowered due to the deterioration by the addition of these additives. Because the traction drive fluid is subjected to quite severe conditions in view of oxidation reaction, the requirement with regard to oxidation stability is also very severe.
Incidentally, various lubricants have been proposed and put into practice for the use in rotating members such as rotary bearings in which parts are rotated freely and substantially independently. For example, a mixture of hydrogenated linear dimer of .alpha.-methylstyrene and hydrogenated linear trimer of the same is proposed In U.S. Pat. No. 3,925,217. However, what is called lubricant oil improves the sliding
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Mochizuki Kanji
Murai Yoshikazu
Yamaguchi Tatsuo
Lieberman Paul
Nippon Petrochemicals Company Ltd.
Skane Christine A.
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