Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic -co- compound
Reexamination Certificate
1999-04-08
2001-06-05
Medley, Margaret (Department: 1721)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic -co- compound
C508S484000, C508S496000, C508S499000, C252S073000, C585S020000, C585S021000, C585S522000
Reexamination Certificate
active
06242393
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to traction drive fluids, more particularly to a traction drive fluid used not only for a power transmission mechanism such as the automatic transmission of traction drive type for an automobile but also for the hydraulic control mechanism thereof as well as the friction characteristics controlling mechanism for the wet clutch.
2. Prior Art
In the industrial machinery field, traction drive fluids have already been used for traction drive type power transmission devices which are designed to transmit power via a film of oil formed at the contacting surfaces of the operative parts. Such traction drive fluids used in these devices are required to have high traction coefficient, i. e. superior power transmission capabilities.
In recent years, extensive studies and investigations on a traction drive fluid have been made for its use of the continuously variable transmission of an automobile. When used for an automobile, the fluid is used not only for the power transmitting mechanism but also for the hydraulic controlling mechanism as well as the friction characteristics controlling mechanism for the wet clutch.
There has been known an automatic transmission fluid (ATF) which is a lubricant used for the hydraulic controlling mechanism and the friction characteristics controlling mechanism for the wet clutch constituting the transmission of an automobile. It is a well-known fact that ATF is required to be higher than a certain level in a kinematic viscosity at elevated temperatures and superior in flowability at low temperatures for performing the role of the hydraulic controlling mechanism. It is also well known that ATF is required to be blended with additives which are excelled in friction characteristics, particularly in shudder resistance characteristics for fulfilling the requirements in performing the role of the friction characteristics controlling mechanism, particularly the controlling mechanism having in addition slip controlling capabilities.
In the case where a traction drive fluid is used for the continuously variable transmission of traction drive type for an automobile, it is necessary for the fluid to have not only inherent superior power transmitting capabilities but also the capabilities required for ATF, that is, capabilities upon being used as a fluid for the hydraulic controlling mechanism and the friction controlling mechanism of the wet clutch.
Although there is a commercially available traction drive fluid sold under the tradename of “SANTOTRAC” which is widely known to have an excellent power transmitting capability, a traction drive fluid suitable for an automobile has not been place on the market because it needs to fulfill the requirements on the capabilities such as a flowability at low temperatures which are expected to exhibit upon being used for the continuously variable transmission of an automobile.
In view of the current situations, an object of the present invention is to provide a traction drive fluid which is excellent in not only power transmitting capabilities but also the capabilities required as a fluid for controlling hydraulic pressure and the friction characteristics of a wet clutch constituting the transmission of an automobile.
SUMMARY OF THE INVENTION
As a result of an extensive research conducted for solving the above-mentioned problems, the present inventors has developed a fluid for a traction drive, particularly a fluid for the continuously variable transmission of traction drive type for an automobile and more particularly such a fluid which can be utilized for a power transmitting mechanism and can be applicable for a hydraulic controlling mechanism as well as the friction characteristics controlling mechanism for the wet clutch.
According to the present invention, there is provided a traction drive fluid which comprises a tractant selected from the group consisting of naphthenic hydrocarbons (A) and (B), naphthenic carboxylates (C) and (D) and a naphthenic carbonate (E),
said naphthenic hydrocarbon (A) being represented by the formula
wherein among R
1
through R
8
, R
4
is a C
1
-C
8
alkyl group which may have a naphthene ring and the remainders each are a hydrogen atom or a C
1
-C
8
alkyl group which may have a naphthene ring;
said naphthenic hydrocarbon (B) being represented by the formula
wherein among R
9
through R
20
, at least more than two members selected arbitrary from R
12
, R
13
and R
16
are C
1
-C
8
alkyl groups which may have a naphthene ring and the remainders each are a hydrogen atom or a C
1
-C
8
alkyl group which may have a naphthene ring;
said naphthenic carboxylate (C) being represented by the formula
wherein R
21
through R
26
each are a hydrogen atom or a C
1
-C
8
alkyl group which may have a naphthene ring;
said naphthenic carboxylate (D) being represented by the formula
wherein R
27
through R
32
each are a hydrogen atom or a C
1
-C
8
alkyl group which may have a naphthene ring; and
said naphthenic carbonate (E) being represented by the formula
wherein R
33
through R
38
each are a hydrogen atom or a C
1
-C
8
alkyl group which may have a naphthene ring.
The inventive traction drive fluid comprises the above-mentioned tractant and a base oil of at least one member selected from a mineral oil and a synthetic oil having a molecular weight of 150-800.
A viscosity index improver is preferably added to the above traction drive fluid. Preferred for such a viscosity index improver is a ethylene-&agr;-olefin copolymer having a number-average molecular weight in excess of 800 and less than 150,000 and hydrides thereof.
Furthermore, the traction drive fluid is preferably blended with a ashless dispersant and a phosphorus-containing additive. More over, the traction drive fluid is preferably blended with a friction adjusting agent having at least one alkyl or alkenyl group of 6-30 carbon atoms in its molecule and having no hydrocarbon group of more than 31 carbon atoms. It is also preferred that the traction drive fluid is blended with a metal-containing detergent having a total base number of 20-450 mgKOH/g.
DETAILED DESCRIPTION OF THE INVENTION
The naphthenic hydrocarbon (A) of the tractant used for the inventive traction drive fluid is represented by the formula
wherein among R
1
through R
8
R
4
is a C
1
-C
8
alkyl group which may have a naphthene ring, preferably C
1
-C
4
alkyl group, more preferably a methyl group and the remainders each are a hydrogen atom or a C
1
-C
8
alkyl group which may have a naphthene ring, preferably a hydrogen atom or a C
1
-C
4
alkyl group, more preferably a hydrogen atom or a methyl group.
Preferred naphthenic hydrocarbons of formula (1) in view of high traction coefficient are those represented by the formula
wherein R
4
is a C
1
-C
8
alkyl group which may have a naphthene ring, preferably C
1
-C
4
alkyl group, more preferably a methyl group, R
1
through R
3
and R
5
through R
8
each are a hydrogen atom or a C
1
-C
8
alkyl group which may have a naphthene ring, preferably a hydrogen atom or a C
1
-C
4
alkyl group, more preferably a hydrogen atom or a methyl group and at least one member, preferably at least more than two members, more preferably at least R
1
and R
6
selected arbitrary from R
1
, R
3
and R
6
each are a C
1
-C
8
alkyl group which may have a naphthene ring, preferably a C
1
-C
4
alkyl group, more preferably a methyl group.
Furthermore, preferred naphthenic hydrocarbons of formula (1) in view of superior viscosity characteristics at low temperatures are those represented by the formula
wherein R
4
is a C
1
-C
8
alkyl group which may have a naphthene ring, preferably C
1
-C
4
alkyl group, more preferably a methyl group, R
1
through R
3
and R
5
through R
8
each are a hydrogen atom or a C
1
-C
8
alkyl group which may have a naphthene ring, preferably a hydrogen atom or a C
1
-C
4
alkyl group, more preferably a hydrogen atom or a methyl group and at least one member selected from R
1
through R
3
and R
5
through R
8
is a C
1
-C
8
alkyl group w
Ishida Noboru
Kohno Junya
Okawa Tetsuo
Shirahama Shinichi
Akin Gump Strauss Hauer & Feld L.L.P.
Medley Margaret
Nippon Mitsubishi Oil Corporation
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