U.S. patent application number 10/424742 was filed with the patent office on 2004-01-08 for lubricating oil composition for automatic transmission.
This patent application is currently assigned to HONDA GIKEN KOGYO KABUSHIKI KAISHA. Invention is credited to Ichihashi, Toshihiko, Watanabe, Nobuaki, Yamane, Tomonori, Yoshida, Junpei.
Application Number | 20040005988 10/424742 |
Document ID | / |
Family ID | 29541776 |
Filed Date | 2004-01-08 |
United States Patent
Application |
20040005988 |
Kind Code |
A1 |
Watanabe, Nobuaki ; et
al. |
January 8, 2004 |
Lubricating oil composition for automatic transmission
Abstract
A lubricating oil composition for automatic transmission
comprises a base oil having a pour point of -25.degree. C. or lower
and a kinematic viscosity of 2 to 7 mm.sup.2/s at 100.degree. C.,
(A) a over-based calcium sulfonate having a total base number of
300 to 500 mg KOH/g, (B) a succinimide having boron atom and/or a
succinimide having no boron atom, which are substituted with a
hydrocarbon group (an alkyl groups or alkenyl groups having an
average molecular weight of 1,000 to 3,500), and, and (C) a
phosphorous acid ester-based compound, each in a specific amount.
The composition has a great statical friction coefficient (.mu.s),
an excellent transmission torque capacity and a friction
characteristic having a .mu. ratio of 1 or smaller, exhibiting
excellent resistance to transmission shock on clutching.
Inventors: |
Watanabe, Nobuaki; (Chiba,
JP) ; Ichihashi, Toshihiko; (Chiba, JP) ;
Yamane, Tomonori; (Tochigi, JP) ; Yoshida,
Junpei; (Tochigi, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
HONDA GIKEN KOGYO KABUSHIKI
KAISHA
Tokyo
JP
Idemitsu Kosan Co., Ltd.
Tokyo
JP
|
Family ID: |
29541776 |
Appl. No.: |
10/424742 |
Filed: |
April 29, 2003 |
Current U.S.
Class: |
508/192 ;
508/291; 508/294; 508/391; 508/433 |
Current CPC
Class: |
C10N 2030/06 20130101;
C10N 2030/52 20200501; C10N 2010/04 20130101; C10M 2223/02
20130101; C10M 169/045 20130101; C10N 2020/04 20130101; C10M 163/00
20130101; C10N 2060/14 20130101; C10M 2215/28 20130101; C10M
2203/0206 20130101; C10M 2223/049 20130101; C10N 2020/02 20130101;
C10N 2040/042 20200501; C10M 2219/046 20130101 |
Class at
Publication: |
508/192 ;
508/291; 508/294; 508/391; 508/433 |
International
Class: |
C10M 11/00; C10M 141/12;
C10M 141/10 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 30, 2002 |
JP |
127829/2002 |
Claims
1. A lubricating oil composition for automatic transmission which
comprises a base oil having a pour point of -25.degree. C. or lower
and a kinematic viscosity of 2 to 7 mm.sup.2/s at a temperature of
100.degree. C., (A) a over-based calcium sulfonate having a total
base number of 300 to 500 mg KOH/g in an amount in a range of 2,000
to 3,500 ppm by mass as calcium, (B) at least one of a succinimide
substituted with a hydrocarbon group and having no boron atom and a
succinimide substituted with a hydrocarbon group and having boron
atom, the succinimides having an alkyl group or an alkenyl group
having an average molecular weight of 1,000 to 3,500, in an amount
such that an amount of nitrogen is in a range of 100 to 500 ppm by
mass and an amount of boron is in a range of 0 to 300 ppm by mass,
and (C) a phosphorous acid ester-based compound in an amount in a
range of 100 to 300 ppm by mass as phosphorus, each amount being
based on an entire amount of the composition.
2. A lubricating oil composition for automatic transmission
according to claim 1, wherein the base oil is a paraffinic highly
purified based oil having a value of % C.sub.A of 0.1% by mass or
smaller.
3. A lubricating oil composition for automatic transmission
according to any one claims 1 and 2, wherein the phosphorous acid
ester-based compound of component (C) is an acidic phosphorous acid
ester.
Description
TECHNICAL FIELD
[0001] The present invention relates to a lubricating oil
composition for automatic transmission. More particularly, the
present invention relates to a lubricating oil composition for
automatic transmission which has a great statical friction
coefficient (.mu.s), an excellent transmission torque capacity and
a friction characteristic having a .mu. ratio of 1 or smaller,
exhibiting excellent resistance to transmission shock on clutching,
and achieves the improvement in the energy saving property and the
decrease in the size and the weight of the automatic
transmission.
BACKGROUND ART
[0002] An automatic transmission fluid (referred to as ATF,
hereinafter) is a lubricating oil composition used for automatic
transmissions of automobiles having a torque converter, a gear
mechanism, a hydraulic mechanism and a wet type clutch at the
inside.
[0003] In order that the mechanism of the automatic transmission
works smoothly, ATF is required to have many functions such as the
function as a medium for transmitting power in the torque
converter, the hydraulic system and the control system, lubrication
of bearings of gears and the wet type clutch, the function as a
medium for adjustment of the temperature, lubrication of friction
materials and retention of the suitable friction property. As the
automatic transmission is more widely used in the automobile field
in recent years, the requirement for ATF having a more excellent
friction property is increasing.
[0004] To improve the efficiency of transmission of the automatic
transmission and also to improve the torque of transmission in the
wet type clutch portion for decreasing the size and the weight of
the transmission, it is required that the friction coefficient of
the clutch be increased. (The torque capacity of a clutch is
evaluated, in general, by the SAE No. 2 tester using an actually
used clutch.)
[0005] In general, the transmission torque capacity is evaluated by
the statical friction coefficient .mu.s. The transmission torque
capacity can be increased by increasing the value of .mu.s. When
the transmission torque capacity is increased, i.e., the statical
friction coefficient .mu.s is increased, in general, the friction
coefficient .mu.0 immediately before stopping by clutching is also
increased. As the result, in general, the ratio of .mu.0 as the
index of the transmission shock to the dynamical friction
coefficient .mu.d (the .mu. ratio) deteriorates and it has been
considered difficult that the .mu. ratio is kept at 1 or greater
while .mu.s is increased.
[0006] However, it is apparent that the .mu. ratio and the value of
.mu.s can be improved simultaneously only when the dynamical
friction coefficient is increased. The development of the
technology for increasing .mu.d has been conducted actively but it
is the actual situation that no satisfactory results have been
obtained.
[0007] In the transmission using conventional ATF, the number and
the diameter of the disk plate are decreased to improve the
transmission efficiency and to decrease the size and the weight of
the transmission. This causes a problem in that the transmission
torque capacity becomes insufficient due to a small friction
coefficient.
[0008] Although various proposals have been made on ATF, these
proposals have some problems and the satisfactory results cannot be
always obtained. For example, in the technology disclosed in
Japanese Patent No. 3184113, the transmission shock on clutching is
great although the torque capacity is good. In the technology
disclosed in Japanese Patent Application Laid-Open No. 2000-160183,
the friction coefficient is small and the transmission torque
capacity is insufficient although the transmission shock on
clutching is absent. When an ashless dispersant containing boron is
used and boron is contained in an amount of 0.035% by mass or more
(350 ppm by mass or more) as disclosed in Japanese Patent
Application Laid-Open No. 2001-279286, a problem arises in that the
transmission shock is great and precipitates are formed since water
tends to be absorbed due to the great amount of boron.
DISCLOSURE OF THE INVENTION
[0009] Under the above circumstances, the present invention has an
object of providing a lubricating oil composition for automatic
transmission which has a great statical friction coefficient
(.mu.s) to achieve the improvement in the energy saving property, a
friction characteristic having a .mu. ratio of 1 or smaller,
exhibiting excellent resistance to transmission shock on clutching,
to achieve the improvement torque capacity for the decrease in the
size and the weight of the automatic transmission.
[0010] As the result of the intensive studies by the present
inventors to develop the lubricating oil composition for automatic
transmission having the above excellent properties, it was found
that the above object could be achieved with a composition
comprising a combination of a base oil having a specific fluidity,
a over-based calcium sulfonate having a total base number in a
specific range, a succinimide substituted with a hydrocarbon group
and having boron atom or no boron atom such as
polybutenylsuccinimide having no boron atom and
polybutenylsuccinimide having boron atoms, and a phosphorous acid
ester-based compound, each in a specific amount based on the entire
amount of the composition. The present invention has been completed
based on this knowledge.
[0011] The present invention provides a lubricating oil composition
for automatic transmission which comprises a base oil having a pour
point of -25.degree. C. or lower and a kinematic viscosity of 2 to
7 mm.sup.2/s at a temperature of 100.degree. C., (A) a over-based
calcium sulfonate having a total base number of 300 to 500 mg KOH/g
in an amount in a range of 2,000 to 3,500 ppm by mass as calcium,
(B) at least one of a succinimide substituted with a hydrocarbon
group and having no boron atom and a succinimide substituted with a
hydrocarbon group and having boron atom, the succinimides having an
alkyl group or an alkenyl group having an average molecular weight
of 1,000 to 3,500, in an amount such that an amount of nitrogen is
in a range of 100 to 500 ppm by mass and an amount of boron is in a
range of 0 to 300 ppm by mass, and (C) a phosphorous acid
ester-based compound in an amount in a range of 100 to 300 ppm by
mass as phosphorus, each amount being based on an entire amount of
the composition.
PREFERRED EMBODIMENT TO CARRY OUT THE INVENTION
[0012] In the lubricating oil composition for automatic
transmission of the resent invention, a base oil having a pour
point of -25.degree. C. or lower and a kinematic viscosity of 2 to
7 mm.sup.2/s at the temperature of 100.degree. C. is used. When the
pour point of the base oil exceeds -25.degree. C., the fluidity at
low temperatures is insufficient. When the kinematic viscosity is
smaller than 2 mm.sup.2/s at the temperature of 100.degree. C., the
vapor pressure is excessively great and the flash point decreases.
Moreover, friction at the sliding portions such as bearings of
gears and the clutch in the automatic transmission increases. A
kinematic viscosity exceeding than 7 mm.sup.2/s is not necessary
for the design of the automatic transmission and there is the
possibility that delay in clutching takes places in transmission
when the kinematic viscosity exceeds 7 mm.sup.2/s.
[0013] The type of the base oil is not particularly limited and any
of mineral oils and synthetic oils can be used. As the mineral oil,
various conventional mineral oils can be used. Examples of the
mineral oil include paraffinic mineral oils, intermediate mineral
oils and naphthenic mineral oils. Specific examples of the mineral
oil include light neutral oil, intermediate neutral oil, heavy
neutral oil and bright stock purified with a solvent or
hydrogen.
[0014] As the synthetic oil, various conventional synthetic oils
can be used. Examples of the synthetic oil include
poly-.alpha.-olefins (including copolymers of .alpha.-olefins),
polybutene, polyol esters, esters of dibasic acids, esters of
phosphoric acid, polyphenyl ether, alkylbenzenes,
alkylnaphthalenes, polyoxyalkylene glycols, neopentyl glycol,
silicone oils, trimethylolpropane, pentaerythritol and hindered
esters. The base oil may be used singly or in combination of two or
more. The mineral oil and the synthetic oil may be used in
combination. In the present invention, paraffinic highly purified
base oils having a value of % C.sub.A of 0.1% by mass or smaller
are preferable from the standpoint of the properties of the
lubricating oil composition. The % C.sub.A is the fraction of
aromatic components obtained in accordance with the n-d-M method of
the ring analysis.
[0015] The lubricating oil composition of the present invention
comprises an over-based calcium sulfonate as component (A). The
over-based calcium sulfonate is a salt selected from calcium salts
of various sulfonic acids and, in general, obtained by carbonation
of a calcium salt of a sulfonic acid. Examples of the sulfonic acid
include aromatic petroleum sulfonic acids, alkylsulfonic acids,
aryl sulfonic acids and alkylarylsulfonic acids. Specific examples
of the sulfonic acid include dodecylbenzenesulfonic acid,
dilaurylcetylbenzenesulfonic acid, benzenesulfonic acid substituted
with paraffin wax, benzenesulfonic acid substituted with
polyolefins, benzenesulfonic acid substituted with polyisobutylene
and naphthalene-sulfonic acid.
[0016] In the present invention, a over-based calcium sulfonate
having a total base number in the range of 300 to 500 mg KOH/g is
used. When the total base number is smaller than 300 mg KOH/g, the
friction oeficient is not sufficiently great. It is difficult that
a over-based calcium sulfonate having a total base number exceeding
500 mg KOH/g is produced.
[0017] The over-based calcium sulfonate may be used singly or in
combination of two or more. The amount is selected in the range of
2,000 to 3,500 ppm by mass as the amount of calcium based on the
entire amount of the composition. When the amount is less than
2,000 ppm by mass, the friction coefficient is not sufficiently
great and the effect of cleaning is insufficient. When the amount
exceeds 3,500 ppm by mass, it is difficult that the value of .mu.
is adjusted at 1 or smaller although the friction coefficient is
sufficiently great.
[0018] The lubricating oil composition of the present invention
comprises, as component (B), at least one of a succinimide
substituted with a hydrocarbon group and having no boron atom and a
succinimide substituted with a hydrocarbon group and having boron
atom. The succinimides have an alkyl group or an alkenyl group
having an average molecular weight of 1,000 to 3,500 and preferably
a polybutenyl group.
[0019] When the average molecular weight of the alkyl group or the
alkenyl group in the succinimide substituted with a hydrocarbon
group and having boron atom or no boron atom is outside the range
of 1,000 to 3,500, the object of the present invention is not
achieved. It is preferable that the hydrocarbon group is a
polybutenyl group and, more preferably a polybutenyl group having
an average molecular weight in the range of 1,000 to 2,500.
[0020] Examples of the succinimide substituted with a hydrocarbon
group and having no boron atom include monopolybutenylsuccinimides
represented by general formula (I): 1
[0021] wherein R.sup.1 represents a polybutenyl group having an
average molecular weight in the range of 1,000 to 3,500, R.sup.2
represents an alkylene group aving 2 to 4 carbon atoms, and m
represents an integer of 1 to 10; and ispolybutenylsuccinimides
represented by general formula (II): 2
[0022] wherein R.sup.3 and R.sup.4 each represent a polybutenyl
group having an average molecular weight in the range of 1,000 to
3,500, R.sup.3 and R.sup.4 may represent the same group or
different groups; R.sup.5 and R.sup.6 each represent an alkylene
group having 2 to 4 carbon atoms, R.sup.5 and R.sup.6 may represent
the same group or different groups, and n represents 0 or an
integer of 1 to 10.
[0023] These polybutenylsuccinimides can be produced, in general,
by reacting a polyalkylenepolyamine with polybutenylsuccinic
anhydride which is obtained by the reaction of polybutene and
maleic anhydride. The monobutenylsuccinimide, the
bisbutenylsuccinimide or a mixture of these compounds can be
obtained when the relative amounts of the nolybutenylsuccinic
anhydride and the polyalkylenepolyamine are changed in the
reaction.
[0024] Examples of the polyalkylenepolyamine used above include
polyethylenepolyamine, polypropylenepolyamine and
polybutylene-polyamine. Among these compounds,
polyethylenepolyamine is preferable.
[0025] Examples of the polybutenylsuccinimide having boron atom
include compounds obtained by reacting the polybutenylsuccinimide
having no boron atom (the mono-compound and/or the bis-compound)
with a boron compound. Examples of the boron compound include boric
acid, boric acid anhydride, boron halides, esters of boric acid,
amides of boric acid and boron oxide.
[0026] In the present invention, at least one compound selected
from the monopolybutenylsuccinimides, bispolybutenylsuccinimides
and polybutenylsuccinimides having boron atom described above is
preferable as component (B). The amount is selected in the range
such that the amount of nitrogen is in the range of 100 to 500 ppm
by mass and preferably in the range of 150 to 350 ppm by mass and
the amount of boron is in the range of 0 to 300 ppm by mass. When
the amount of nitrogen is less than 100 ppm by mass, the torque
transmission capacity decreases and dispersion of the degradation
products deteriorates. When the amount of nitrogen exceeds 500 ppm
by mass or the amount of boron exceeds 300 ppm by mass,
transmission shock and shudder tend to take place.
[0027] The lubricating composition of the present invention
comprises a phosphorous acid ester-based compound as component (C).
Examples of the phosphorous acid ester-based compound include
compounds represented by general formula (III): 3
[0028] wherein R.sup.7 to R.sup.9 each represent hydrogen atom or a
hydrocarbon group having 4 to 30 carbon atoms, the atoms and the
groups represented by R.sup.7 to R.sup.9 may be the same with or
different from each other, and at least one of R.sup.7 to R.sup.9
represents a hydrocarbon group having 4 to 30 carbon atoms.
[0029] Examples of the hydrocarbon group having 4 to 30 carbon
atoms represented by R.sup.7 to R.sup.9 in general formula (III)
include linear, branched and cyclic alkyl groups and alkenyl groups
having 4 to 30 carbon atoms, aryl groups having 6 to 30 carbon
atoms, alkylaryl groups having 7 to 30 carbon atoms and arylalkyl
groups having 7 to 30 carbon atoms. Specific examples of the above
hydrocarbon group include butyl group, pentyl group, hexyl group,
cyclohexyl group, octyl group, decyl group, lauryl group, myristyl
group, palmityl group, stearyl group, oleyl group, eicosyl group,
phenyl group, xylyl group, benzyl group and phenethyl group.
[0030] The phosphorous acid ester-based compound represented by
general formula (III) include phosphorous acid esters represented
by general formula (III) in which R.sup.7 to R.sup.9 each represent
a hydrocarbon group, acidic phosphorous acid esters represented by
general formula (III) in which one of R.sup.7 to R.sup.9 represents
hydrogen atom and the rest of R.sup.7 to R.sup.9 each represent a
hydrocarbon group (monohydrogenphosphites) and acidic phosphorous
acid esters represented by general formula (III) in which two of
R.sup.7 to R.sup.9 each represent hydrogen atom and the rest of
R.sup.7 to R.sup.9 represents a hydrocarbon group
(dihydrogenphosphites). In the present invention, acidic
phosphorous acid esters are preferable and monohydrogenphosphites
are more preferable.
[0031] Examples of the monohydrogenphosphite include dibutyl
hydrogenphosphite, dilauryl hydrogenphosphite, dioleyl
hydrogen-phosphite, distearyl hydrogenphosphite, diphenyl
hydrogenphosphite and dibenzyl hydrogenphosphite. Among these
compounds, dilauryl hydrogenphosphite and dioleyl hydrogenphosphite
are preferable.
[0032] In the present invention, the phosphorous acid ester-based
compound described above may be used singly or in combination of
two or more. The amount is in the range of 100 to 300 ppm by mass
as the amount of phosphorus based on the entire amount of the
composition. When the amount is less than 100 ppm by mass, it is
difficult that the value of .mu. is adjusted at 1.0 or smaller and
the object of the present invention is not achieved. When the
amount exceeds 300 ppm by mass, the friction coefficient decreases
and the transmission torque is insufficient.
[0033] Where desired, the lubricating oil composition of the
present invention may further comprise other additives such as
antioxidants, viscosity index improvers, extreme pressure agents,
friction modifiers, rust preventives, corrosion inhibitors and
defoaming agents as long as the object of the present invention is
not adversely affected.
[0034] Examples of the antioxidant include amine-based antioxidants
such as alkylated diphenylamine, phenyl-.alpha.-naphthylamine and
alkylated .alpha.-naphthylamine; phenol-based antioxidants such as
2,6-di-t-butyl-4-methylphenol and
4,4'-methylenebis(2,6-di-t-butylphenol)- ; and sulfur-based
antioxidants such as dilauryl thiodipropionate and distearyl
thiodipropionate.
[0035] Examples of the viscosity index improver include
polymethacrylate-based viscosity index improvers,
polyisobutylene-based viscosity index improvers, ethylene-propylene
copolymer-based viscosity index improvers and hydrogenated
styrene-butadiene copolymer-based viscosity index improvers.
[0036] Examples of the extreme pressure agent and the friction
modifier include esters of phosphoric acid, carboxylic acids,
esters of carboxylic acids, oils and fats, amides of carboxylic
acids (reaction products of amines such as polyalkylenepolyamines,
alkanolamines and alkylamines with carboxylic acids), alkylamines,
N-alkylalkanolamines and partial esters of carboxylic acids and
polyhydric alcohols.
[0037] Examples of the rust preventive include alkenylsuccinic
acids and partial esters of alkenylsuccinic acids. Examples of the
corrosion inhibitor include benzotriazole and benzimidazole.
Examples of the defoaming agent include dimethylpolysiloxane and
polyacrylates.
[0038] The lubricating oil composition of the present invention
having the above composition has, in general, a value of .mu.s of
1.2 or greater, exhibiting the excellent transmission torque
capacity, and, at the same time, a .mu. ratio of 1 or smaller,
exhibiting the excellent resistance to transmission shock.
Therefore, the improvement in the energy saving property and the
decreases in the size and the weight of the automatic transmission
can be achieved.
[0039] The lubricating oil composition of the present invention can
be applied to transmissions equipped with an automatic transmission
and a friction materal mechanism of the wet type. joints having a
friction material mechanism of the wet type for braking and
automatic/non-stage transmissions having a lock up clutch equipped
with a continuous slipping mechanism.
EXAMPLE
[0040] The present invention will be described more specifically
with reference to examples in the following. However, the present
invention is not limited to the examples.
Examples 1 to 3 and Comparative Examples 1 to 8
[0041] Lubricating oil compositions were prepared in accordance
with the formulations shown in Table 1 and the dynamical friction
coefficient (.mu.d) and the stillness friction coefficient (.mu.0)
were evaluated under the dynamic condition and the statical
friction coefficient (.mu.s) was evaluated under the static
condition using the SAE No. 2 friction tester. The conditions of
the evaluations are shown in the following.
[0042] A cellulose-based clutch material actually used for
transmissions was used under the following conditions: the face
pressure: 0.2 to 0.3 N/mm.sup.2; the oil temperature: 100.degree.
C.; the dynamic speed of rotation: 3,000 rpm; and the static speed
of rotation: 0.7 rpm.
[0043] Under the above test conditions, .mu.d and .mu.s at 3,000
rpm were measured and the .mu. ratio (.mu.0/.mu.d) was obtained.
When the .mu. ratio is 1 or smaller, the resistance to transmission
shock is excellent.
[0044] The results are shown in Table 1.
[0045] The components used for the compositions are shown in the
following.
[0046] (1) Base Oil
[0047] A paraffinic oil having a pour point of -30.degree. C., a
kinematic viscosity of 3.5 mm.sup.2/s at 100.degree. C. and a %
C.sub.A of 0.1% by mass or smaller.
[0048] (2) Over-Based Calcium Sulfonates
[0049] 250TBN: calcium sulfonate having a total base number of 230
mg/KOH.
[0050] 300TBN: calcium sulfonate having a total base number of 330
mg/KOH.
[0051] 400TBN: calcium sulfonate having a total base number of 400
mg/KOH.
[0052] (3) Polybutenylsuccinimides
[0053] High molecular weight Mw2000: a polybutenylsuccinimide
having a nitrogen content of 1.5% by mass and no boron atom, in
which the average molecular weight of the polybutenyl group was
2,000.
[0054] B-based Mw1000-1: a polybutenylsuccinimide having a nitrogen
content of 1.6% by mass and a boron content of 0.4% by mass, in
which the average molecular weight of the polybutenyl group was
1,000.
[0055] B-based Mw1000-2: a polybutenylsuccinimide having a nitrogen
content of 2.0% by mass and a boron content of 2.0% by mass, in
which the average molecular weight of the polybutenyl group was
1,000.
[0056] Low molecular weight Mw1000>: a polybutenylsuccinimide
having a nitrogen content of 3.6% by mass and no boron atom, in
which the average molecular weight of the polybutenyl group was
500.
[0057] (4) Acidic Phosphorous Acid Ester
[0058] Dioleyl hydrogenphosphite
[0059] (5) Antioxidant
[0060] A combination of a phenol-based antioxidant and an
amine-based antioxidant
[0061] (6) Viscosity Index Improver
[0062] A PMA-based viscosity index improver
1 TABLE 1-1 Comparative Example Example 1 2 3 1 2 3 Composition (%
by mass) paraffinic base oil rest rest rest rest rest rest calcium
sulfonate 250 TBN -- -- -- -- -- -- 300 TBN -- -- 3.0 -- -- -- 400
TBN 2.0 2.0 -- 1.0 2.0 2.0 polybutenylsuccinimide high molecular
weight 2.0 -- 2.0 2.0 -- -- Mw2000 B-based Mw1000-1 -- 2.0 -- -- --
-- B-based Mw1000-2 -- -- -- -- 2.0 -- low molecular weight -- --
-- -- -- 4.5 Mw1000> acidic phosphorous acid ester 0.4 0.3 0.4
0.4 0.4 0.4 antioxidant 1.0 1.0 1.0 1.0 1.0 1.0 viscosity index
improver etc 11*.sup.1 11*.sup.1 11*.sup.1 11*.sup.1 11*.sup.1
11*.sup.1 Elements in additives added to the composition (ppm by
mass) Ca 3000 3000 3000 1500 3000 3000 N 300 200 300 300 300 300 P
250 200 250 250 200 250 B 0 100 0 0 350 0 Friction properties by
SAE No. 2 test .mu.d 0.16 0.16 0.16 0.13 0.14 0.14 .mu.s 0.12 0.13
0.13 0.08 0.09 0.09 .mu. ratio 0.92 0.90 0.94 0.94 0.92 0.90
[0063]
2 TABLE 1-2 Comparative Example 4 5 6 7 8.sup.*2 Composition (% by
mass) paraffinic base oil rest rest rest rest rest calcium
sulfonate 250 TBN 5.0 -- -- -- -- 300 TBN -- -- -- -- -- 400 TBN --
2.0 4.0 2.0 2.0 polybutenylsuccinimide high molecular weight 2.0
2.0 2.0 4.0 -- Mw2000 B-based Mw1000-1 -- -- -- -- -- B-based
Mw1000-2 -- -- -- -- -- low molecular weight -- -- -- -- --
Mw1000> acidic phosphorous acid 0.4 -- 0.8 0.4 0.4 ester
antioxidant 1.0 1.0 1.0 1.0 1.0 viscosity index improver 11*.sup.1
11*.sup.1 11*.sup.1 11*.sup.1 11*.sup.1 etc Elements in additives
added to the composition (ppm by mass) Ca 3000 3000 6000 3000 3000
N 300 300 300 600 0 P 250 0 500 250 250 B 0 0 0 0 0 Friction
properties by SAE No. 2 test .mu.d 0.13 0.17 0.17 0.13 0.14 .mu.s
0.08 0.16 0.12 0.09 0.12 .mu. ratio 0.93 1.05 1.01 0.90 0.95 Notes
.sup.*1Viscosity index improver: 10% and others: 1%
.sup.*2Precipitates were formed.
[0064] As shown in Table 1, the lubricating oil compositions of the
present invention all showed .mu.s of 0.12 or greater, exhibiting
great transmission torque capacities, and .mu. ratios of 1.0 or
smaller, exhibiting excellent resistance to transmission shock.
INDUSTRIAL APPLICABILITY
[0065] In accordance with the present invention, the lubricating
oil composition for automatic transmission which has a great
statical friction coefficient (.mu.s), an excellent transmission
torque capacity and a friction characteristic having a .mu. ratio
of 1 or smaller, exhibiting excellent resistance to transmission
shock on clutching, and achieves the improvement the energy saving
property and the decrease in the size and the weight of the
automatic transmission, can be provided.
* * * * *