FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
& The Patent Rules, 2003
COMPLETE SPECIFICATION
1.TITLE OF THE INVENTION:
USE OF A TRIAZOLE COMPOUND AS AN ADDITIVE FOR IMPROVING THE ANTICORROSION PROPERTIES OF A LUBRICANT COMPOSITION FOR A PROPULSION
SYSTEM OF AN ELECTRIC OR HYBRID VEHICLE
2. APPLICANT:
Name: TOTAL MARKETING SERVICES
Nationality: France
Address: 24 Cours Michelet, 92800 PUTEAUX, France.

3. PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes the invention and the manner in
which it is to be performed:
2
Description

The present invention relates to the field of lubricant compositions for a propulsion system
of an electric or hybrid vehicle. The invention more particularly relates to the use of triazole
compounds as additives for improving the anticorrosion properties of a lubricant
composition incorporating one or more amine-based and/or sulfur-based antiwear additives.
Technical field
The changes in the international standards for the reduction of CO2 emissions, but also for
the reduction of energy consumption, has driven motor vehicle constructors toward
proposing alternative solutions to combustion engines.
One of the solutions identified by motor vehicle constructors consists in replacing
combustion engines with electric motors. The research aimed at reducing CO2 emissions has
thus led to the development of electric vehicles by a certain number of motor vehicle
companies.
For the purposes of the present invention, the term “electric vehicle” denotes a vehicle
comprising an electric motor as sole means of propulsion, as opposed to a hybrid vehicle
which comprises a combustion engine and an electric motor as combined means of
propulsion.
For the purposes of the present invention, the term “propulsion system” denotes a system
comprising the mechanical parts required for propelling an electric vehicle. The propulsion
system thus more particularly encompasses an electric motor, comprising the rotor-stator
assembly of the power electronics (dedicated to regulating the speed), a transmission and a
battery.
In general, it is necessary to use, in electric or hybrid vehicles, lubricant compositions, also
known as “lubricants”, for the main purposes of reducing the friction forces between the
various parts of the propulsion system of the vehicle, notably between the metal parts in
motion in the motors. These lubricant compositions are also effective for preventing
premature wear or even damage of these parts, and in particular of their surface.
3
To do this, a lubricant composition is conventionally composed of one or more base oils
which are generally combined with several additives intended for stimulating the lubricant
performance of the base oil, for instance friction-modifying additives, but also for affording
additional performance.
In particular, “antiwear” additives are considered in order to reduce the wear of the parts of
the propulsion system, notably the mechanical parts of the motor, and thus to prevent
degradation of the durability of the motor.
A wide variety of antiwear additives exists, among which mention may be made, for
example, of dimercaptothiadiazoles, polysulfides, notably sulfur-based olefins, amine
phosphates, or else phospho-sulfur additives, for instance metal alkylthiophosphates, in
particular zinc alkylthiophosphates and more specifically zinc dialkyldithiophosphates or
ZnDTP.
Among these antiwear additives, the ones that are notably favored are amine-based and/or
sulfur-based antiwear agents, such as dimercaptothiadiazoles, zinc dithiophosphate or
polysulfides.
Unfortunately, these amine-based and/or sulfur-based antiwear additives, such as
dimercaptothiadiazoles, have the drawback of being corrosive. The problem of corrosion is
particularly critical in electric propulsion systems. In particular, corrosion can lead to a risk
of deterioration of the stator and rotor windings, the sensors in the propulsion system, the
solenoid valves in the hydraulic system, but also of the rolling bearings between the rotor
and stator of an electric motor, which are generally copper-based and thus particularly
susceptible to corrosion, or to the seals or varnishes in the propulsion system.
In addition, in order to be able to cool the propulsion systems of electric or hybrid vehicles,
it is essential that the lubricant be insulating in order to avoid any failure in the electrical
components. In particular, a conductive lubricant can lead to a risk of electrical current
leakage in the stator and rotor windings, which thus reduces the efficiency of the propulsion
systems, and creates possible overheating of the electrical components, even to the point of
damaging the system. In the context of using lubricants for electric or hybrid vehicle
powertrain systems, it is thus crucial for the lubricants to have good “electrical” properties
in addition to non-corrosive properties.
The present invention is directed, specifically, towards overcoming this drawback.
4
Summary of the invention
More precisely, the present invention relates to the use of at least one triazole compound, as
an additive for improving the anticorrosion properties of a lubricant composition intended
for a propulsion system of an electric or hybrid vehicle and comprising one or more aminebased and/or sulfur-based antiwear additives.
Triazole compounds, for instance triazoles, notably 1,2,3-triazole and derivatives thereof or
else benzotriazole and derivatives thereof, are already known for their corrosion-inhibiting
properties, as described, for example, in document EP 1 159 380.
To the inventors’ knowledge, it has, however, never been proposed to use triazole
compounds, together with one or more amine-based and/or sulfur-based antiwear additives,
in the context of using a lubricant for a propulsion system of an electric or hybrid vehicle, to
simultaneously improve the antiwear properties and the anticorrosion properties.
Surprisingly, as illustrated in the example that follows, the inventors have found that the
addition according to the invention of a triazole compound in a lubricant composition
dedicated to a propulsion system of an electric or hybrid vehicle, together with an aminebased and/or sulfur-based antiwear additive, such as a dimercaptothiadiazole additive, makes
it possible to efficiently inhibit corrosion, unlike in particular other additives, which are
nevertheless known as anticorrosion additives, such as organic acid esters, N-acyl
sarcosines, for example N-oleoyl-sarcosine or imidazoline derivatives.
Thus, the specific combination of at least one triazole compound and at least one aminebased and/or sulfur-based antiwear additive makes it possible to reduce, or even to avoid,
the corrosion notably caused by the presence within the lubricant composition of said aminebased and/or sulfur-based antiwear additive(s).
For the purposes of the present invention, the term “anticorrosion additive” denotes an
additive for preventing or reducing the corrosion of metal parts. An anticorrosion additive
thus makes it possible to confer good “anticorrosion properties” on a composition which
contains it.
The use of one or more triazole compounds according to the invention together with one or
more amine-based and/or sulfur-based antiwear additives advantageously affords access to
a lubricant composition which simultaneously has good antiwear performance, while at the
same time overcoming the corrosion problems mentioned previously. A composition
5
according to the invention thus simultaneously has good antiwear and anticorrosion
properties.
The corrosive (or corroding) power of a compound may be evaluated by means of a test
involving study of the variation in the electrical resistance value of a copper wire of a
preestablished diameter, as a function of the duration of immersion of this wire in a
composition comprising said test compound in a noncorrosive medium, for example in one
or more base oils. The variation in this electrical resistance value is directly correlated with
the variation in the diameter of the test wire. Thus, in the context of the present invention, a
compound is termed “noncorrosive” when the loss of diameter of the copper wire studied is
less than or equal to 0.5 µm after immersion for 80 hours, in particular less than or equal to
0.2 µm after immersion for 20 hours in the composition comprising said compound.
The dielectric properties of a lubricant are notably represented by the electrical resistivity
and the dielectric loss (tan δ) and may be measured according to the standard IEC 60247.
The electrical resistivity represents the capacity of a material to oppose the circulation of an
electric current. It is expressed in ohm-metres (Ω.m). The resistivity must not be low to
prevent electrical conduction.
The electric dissipation factor or the loss angle tangent. The loss angle δ is the
complementary angle of the phase shift between the applied voltage and the alternating
current. This factor reflects the Joule-effect energy losses. Heating is thus directly linked to
the δ value. A transmission oil typically has a tan δ value of the order of unity at ambient
temperature. A good insulating lubricant must maintain a low tan δ level.
Advantageously, the triazole compound used according to the invention is chosen from
optionally substituted triazoles, in particular 1,2,3-triazole; benzotriazoles and derivatives
thereof, in particular tolyltriazole (also called tolutriazole) and derivatives thereof, and
tetrahydrobenzotriazoles and derivatives thereof; and mixtures thereof.
Preferably, the triazole compound is a benzotriazole or one of the derivatives thereof,
preferably a benzotriazole derivative, more preferentially a tolyltriazole derivative.
The introduction, into a lubricant composition intended for a propulsion system of an electric
or hybrid vehicle, of one or more triazole compounds according to the invention thus
advantageously permits the use, in the composition, of amine-based and/or sulfur-based
antiwear additives, such as dimercaptothiadiazoles, without, however, entailing an adverse
corrosive effect.
6
The amine-based and/or sulfur-based antiwear additives used in a lubricant composition
according to the invention are more particularly detailed in the text hereinbelow. They are
preferably chosen from amine-based and sulfur-based antiwear additives. They may
preferably be thia(di)azole compounds, in particular dimercaptothiadiazole derivatives.
In addition, a composition that is suitable for use in the invention has the advantage of being
easy to formulate. Besides good antiwear and anticorrosion performance, it has good
stability, notably with respect to oxidation, and also good properties in terms of electrical
insulation.
The present invention also relates to the use, for lubricating a propulsion system of an electric
or hybrid vehicle, in particular for lubricating the electric motor and the power electronics
of an electric or hybrid vehicle, of a lubricant composition comprising:
- one or more anticorrosion additives of triazole type as defined in the invention; and
- one or more amine-based and/or sulfur-based antiwear additives as defined in the invention.
A subject of the present invention is also a process for lubricating a propulsion system of an
electric or hybrid vehicle, comprising at least one step of placing at least one mechanical
part of said system in contact with a lubricant composition comprising at least one additive
of triazole type as defined in the invention and at least one amine-based and/or sulfur-based
antiwear additive as defined in the invention.
Advantageously, a lubricant composition according to the invention is used for lubricating
the electric motor itself, in particular the rolling bearings located between the rotor and the
stator of an electric motor, and/or the transmission, in particular the reducer, in an electric or
hybrid vehicle.
Other features, variants and advantages of the use of triazole compounds according to the
invention will emerge more clearly on reading the description and the examples that follow,
which are given as nonlimiting illustrations of the invention.
In the continuation of the text, the expressions “between… and…”, “ranging from… to…”
and “varying from… to…” are equivalent and are intended to mean that the limits are
included, unless otherwise mentioned.
Brief description of the drawings
[Fig 1] schematically represents a propulsion system of an electric or hybrid vehicle.
7
Detailed description
ADDITIVES OF TRIAZOLE TYPE
As stated previously, the additive used as anticorrosion agent according to the invention,
together with one or more amine-based and/or sulfur-based antiwear additives, in a lubricant
composition for the powertrain system of an electric or hybrid vehicle, is a triazole
compound.
Triazole compounds are already known for their anticorrosion properties.
However, as indicated previously, such compounds have never been proposed, together with
the use of one or more amine-based and/or sulfur-based antiwear additives, in a lubricant
composition intended for a propulsion system of an electric or hybrid vehicle.
Triazole compounds are monocyclic or polycyclic compounds comprising at least one 5-
membered ring incorporating three nitrogen atoms.
Triazole compounds are more particularly chosen from triazoles and derivatives thereof.
Triazoles of general formula C2H3N3 may exist in the forms below, respectively 1H-1,2,3-
triazole, 2H-1,2,3-triazole, 1H-1,2,4-triazole and 4H-1,2,4-triazole:
[Chem 1]
Benzotriazole compounds are specific triazole derivatives comprising a triazole ring coupled
with a benzene ring, as shown below:
8
[Chem 2]
The triazole compound used according to the invention is preferably chosen from optionally
substituted triazoles, in particular 1,2,3-triazole; benzotriazoles and derivatives thereof, in
particular tolyltriazole and derivatives thereof and tetrahydrobenzotriazoles and derivatives
thereof; and mixtures thereof.
The triazole compound may thus be chosen from optionally substituted triazoles, in
particular 1,2,3-triazole; benzotriazoles and derivatives thereof; and mixtures thereof,
preferably it is a benzotriazole derivative, more preferentially a tolyltriazole derivative.
Substituted triazoles which may be mentioned in particular are 1,2,3-triazoles substituted by
one or more groups chosen from alkyl, arylamino and acyl groups.
According to a particular embodiment, the additive of triazole type used according to the
invention may be chosen from 1,2,3-triazole and derivatives thereof, corresponding to
formula (I) below:
[Chem 3]
in which R, R’ and R’’ are chosen, independently of each other, from a hydrogen, an alkyl
group, preferably a C1 to C24 alkyl group, an amine group such as a group –NR1R
2
, an acyl
group such as a group -COR3
, or an aryl group such as a phenyl or tolyl group; with R1
, R2
and R3
being chosen, independently of each other, from a hydrogen atom or a C1 to C24,
preferably C2 to C18, alkyl group.
Benzotriazole derivatives which may be mentioned in particular are benzotriazoles
substituted by one or more groups chosen, for example, from alkyl groups, for instance
tolutriazole (also called tolyltriazole), ethylbenzotriazole, hexylbenzotriazole,
9
octylbenzotriazole, etc., alkyl groups substituted by one or more amine functions, aryl
groups, for instance a phenolbenzotriazole, alkylaryl or arylalkyl groups, or other
substituents such as hydroxy, alkoxy, halogen etc. groups.
According to a particularly preferred embodiment, the additive of triazole type used
according to the invention may be chosen from benzotriazole and derivatives thereof, in
particular corresponding to formula (II) below:
[Chem 4]
in which R and R’
are chosen, independently of each other, from a hydrogen atom, a C1 to
C24 alkyl group, optionally substituted by one or more groups -NR4R
5
; a group -NR1R
2
; an
acyl group of type -COR3
and an aryl group such as a phenyl or tolyl group;
with R1
, R2
and R3
being chosen, independently of each other, from a hydrogen atom or a C1
to C24, preferably C2 to C18, alkyl group;
and R4
and R5
representing, independently of each other, a hydrogen atom, a linear or
branched, preferably branched, C3 to C14, preferably C6 to C12, alkyl group.
Preferably, the triazole compound is tolyltriazole or one of the derivatives thereof.
Preferably, the triazole compound is a tolyltriazole derivative of formula (IIa) below:
[Chem 5]
in which R4
and R5
are, independently of each other, as defined above for formula (II); and
-A- represents a linear or branched, preferably linear, C1 to C6, preferably C1 to C3, alkylene
10
group and more preferentially a methylene group (-CH2-),
in particular, said tolyltriazole derivative being 2-ethyl-N-(2-ethylhexyl)-N-[(4-
methylbenzotriazol-1-yl)methyl]hexan-1-amine.
According to a particular embodiment, the triazole compound is of formula (IIa), in which
R
4
and R5
represent branched C6 to C12 alkyl groups and -A- represents a C1 to C3 alkylene
group, preferably a methylene group.
In the context of the present invention, and unless indicated otherwise, the following
definitions apply :
A halogen represents an atom chosen from fluorine, le chlorine, le bromine or iodine.
An alkyl group represents a linear or branched hydrocarbon-based chain. For example, a CxCz alkyl group represents a linear or branched hydrocarbon-based chain comprising from x
to z carbon atoms.
An alkylene group represents a linear or branched divalent alkyl group. For example, a CxCz alkylene group represents a linear or branched divalent hydrocarbon-based chain of x to
z carbon atoms.
An alkoxy group represents a radical -O-alkyl, in which the alkyl group is as defined
previously.
An aryl group represents a monocyclic or polycyclic aromatic group in particular comprising
between 6 and 10 carbon atoms. Examples of aryl groups that may be mentioned include
phenyl and naphthyl groups.
Preferably, the triazole compound is a benzotriazole or one of the derivatives thereof,
preferably a benzotriazole derivative, more preferentially a tolyltriazole derivative.
The triazole compounds required according to the invention may be commercially available
or prepared according to synthetic methods known to those skilled in the art.
The invention is not limited to the triazole compounds specifically described above. Other
triazole compounds, notably triazole or benzotriazole derivatives, notably tolyltriazole
derivatives, may be used as anticorrosion additives according to the invention.
It is understood that, in the context of the present invention, a triazole compound may be in
the form of a mixture of at least two triazole compounds, in particular as defined previously.
The triazole compound(s), in particular as defined previously, may be used in a lubricant
composition according to the invention in a proportion of from 0.01% to 5% by mass, in
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particular from 0.1% to 3% by mass, and more particularly from 0.5% to 2% by mass,
relative to the total mass of the lubricant composition.
LUBRICANT COMPOSITION
Amine-based and/or sulfur-based antiwear additives
As indicated previously, a lubricant composition under consideration according to the
invention comprises one or more amine-based and/or sulfur-based antiwear additives.
The term “amine-based and/or sulfur-based antiwear additive” denotes an additive chosen
from amine-based antiwear additives, sulfur-based antiwear additives and amine-based and
sulfur-based antiwear additives.
The term “antiwear additive” denotes a compound which, when used in a lubricant
composition, notably a lubricant composition for a propulsion system of an electric or hybrid
vehicle, makes it possible to improve the antiwear properties of the composition.
The amine-based and/or sulfur-based antiwear additive may be chosen, for example, from
additives of thia(di)azole type, in particular dimercaptothiadiazole derivatives; polysulfide
additives, notably sulfur-based olefins; amine phosphates; phospho-sulfur additives such as
alkylthiophosphates; and mixtures thereof.
Thia(di)azole additives
According to a particularly preferred embodiment, a lubricant composition under
consideration according to the invention comprises at least one thia(di)azole antiwear
additive.
Thia(di)azole compounds are compounds which contain both a sulfur atom and at least one
nitrogen atom in a five-atom ring. Benzothiazoles are a particular type of thia(di)azoles. This
term “thia(di)azole” includes, besides cyclic compounds containing one sulfur atom and one
nitrogen atom per five-atom ring, also thiadiazoles which contain sulfur and two nitrogen
atoms in such a ring.
In particular, the thia(di)azole compounds may be chosen from benzothiazole derivatives,
thiazole derivatives and thiadiazole derivatives.
Preferably, the antiwear additive may be a thiadiazole derivative.
Thiadiazoles are heterocyclic compounds comprising two nitrogen atoms, one sulfur atom,
two carbon atoms and two double bonds, of general formula C2N2SH2, which may exist in
the following forms, respectively: 1,2,3-thiadiazole; 1,2,4-thiadiazole; 1,2,5-thiadiazole;
1,3,4-thiadiazole:
12
[Chem 6]
Preferably, the thiadiazole derivative is a dimercaptothiadiazole derivative.
Thus, according to a particularly preferred embodiment, a lubricant composition according
to the invention comprises at least one antiwear additive chosen from dimercaptothiazole
derivatives.
The term “dimercaptothiadiazole derivative” according to the invention means chemical
compounds derived from the following four dimercaptothiadiazole molecules below: 4,5-
dimercapto-1,2,3-thiadiazole, 3,5-dimercapto-1,2,4-thiadiazole, 3,4-dimercapto-1,2,5-
thiadiazole, 2,5-dimercapto-1,3,4-thiadiazole, taken alone or as a mixture:
13
[Chem 7]
The dimercaptothiadiazole derivatives are more particularly molecules or a mixture of
molecules based on 4,5-dimercapto-1,2,3-thiadiazole, 3,5-dimercapto-1,2,4-thiadiazole,
3,4-dimercapto-1,2,5-thiadiazole or 2,5-dimercapto-1,3,4-thiadiazole, as represented above,
in which at least one of the substitutions =S, or even both substitutions =S on the thiadiazole
ring is replaced with a substituent:
[Chem 8]
in which * represents the bond with a carbon atom of the 5-membered ring; n represents an
integer equal to 1, 2, 3 or 4; and R1 is chosen from a hydrogen atom, a linear or branched,
saturated or unsaturated alkyl group comprising from 1 to 24, preferably from 2 to 18, more
preferentially from 4 to 16 and even more preferentially from 8 to 12 carbon atoms or an
aromatic substituent.
14
In particular, taking 2,5-dimercapto-1,3,4-thiadiazole as example, the 2,5-dimercapto-1,3,4-
thiadiazole derivatives are molecules having the following formulae, taken alone or as a
mixture:
[Chem 9]
[Chem 10]
in which the group(s) R1 represent, independently of each other, hydrogen atoms, linear or
branched alkyl or alkenyl groups comprising from 1 to 24, preferably from 2 to 18, more
preferentially from 4 to 16 and even more preferentially from 8 to 12 carbon atoms or
aromatic substituents, n being, independently of each other, integers equal to 1, 2, 3 or 4, n
preferably being equal to 1.
Preferably, R1 represent, independently of each other, linear C1 to C24, preferably C2 to C18,
notably C4 to C16, more particularly C8 to C12 and preferably C12 alkyl groups.
The dimercaptothiadiazole derivatives used in the present invention may be commercially
available, for example from the suppliers Vanderbilt, Rhein Chemie or Afton.
Polysulfide additives
The amine-based and/or sulfur-based antiwear additive(s) used in a lubricant composition
according to the invention may also be chosen from sulfur-based antiwear additives of
polysulfide type, in particular sulfur-based olefins.
The sulfur-based olefins used in a lubricant composition according to the invention may
notably be dialkyl sulfides represented by the general formula Ra-Sx-Rb, in which Ra and Rb
15
are alkyl groups including from 3 to 15 carbon atoms, preferentially from 1 to 5 carbon
atoms, preferentially 3 carbon atoms, and x is an integer between 2 and 6.
Preferably, the polysulfide additive is chosen from dialkyl trisulfides.
Preferably, the antiwear additive present in a composition used according to the invention is
chosen from amine-based and sulfur-based antiwear additives, and advantageously from
thia(di)azole compounds as described above and more preferentially from
dimercaptothiadiazole derivatives.
A lubricant composition under consideration according to the invention may comprise from
0.01% to 5% by mass, in particular from 0.1% to 3% by mass, and more particularly from
0.5% to 2% by mass, of amine-based and/or sulfur-based antiwear additive(s), preferably of
thia(di)azole type and more preferentially chosen from dimercaptothiadiazole derivatives,
relative to the total mass of the lubricant composition.
The use of other antiwear additives, notably known for lubricants for propulsion systems,
other than amine-based and/or sulfur-based additives, is envisageable, provided that they do
not affect the properties imparted by the combination of said triazole compound(s) and of
said amine-based and/or sulfur-based antiwear additive(s) according to the invention.
Preferably, a lubricant composition required according to the invention is free of antiwear
additives other than said amine-based and/or sulfur-based antiwear additive(s) used
according to the invention.
According to a particularly preferred embodiment, a lubricant composition under
consideration according to the invention combines:
- one or more additives of triazole type chosen from benzotriazole derivatives, preferably
tolyltriazole derivatives, and notably those of formula (IIa) indicated above; and
- one or more amine-based and sulfur-based antiwear additives, preferably chosen from
dimercaptothiazole derivatives, in particular as defined above.
According to a particularly preferred embodiment, a lubricant composition under
consideration according to the invention combines, as amine-based and/or sulfur-based
antiwear additive, a 2,5-dimercapto-1,3,4-thiadiazole derivative and, as triazole compound,
a tolyltriazole derivative, in particular 2-ethyl-N-(2-ethylhexyl)-N-[(4-methylbenzotriazol1-yl)methyl]hexan-1-amine.
16
LUBRICANT COMPOSITION
A composition used according to the invention may comprise, besides one or more additives
of triazole type and one or more amine-based and/or sulfur-based antiwear additives, in
particular as defined previously, one or more base oils, and also other additives,
conventionally considered in lubricant compositions.
Base oil
A lubricant composition under consideration according to the invention may thus comprise
one or more base oils.
These base oils may be chosen from the base oils conventionally used in the field of lubricant
oils, such as mineral, synthetic or natural, animal or plant oils or mixtures thereof.
It may be a mixture of several base oils, for example a mixture of two, three or four base
oils.
In the continuation of the text, the term “fluid base” will denote the base oil or mixture of
base oils of the lubricant composition under consideration according to the invention.
The base oils of the lubricant compositions under consideration according to the invention
may in particular be oils of mineral or synthetic origin belonging to groups I to V according
to the classes defined in the API classification (or equivalents thereof according to the
ATIEL classification) and presented in Table 1 below or mixtures thereof.
[Table 1]
Content of
saturates
Sulfur content Viscosity index (VI)
Group I
Mineral oils < 90% > 0.03% 80 ≤ VI < 120
Group II
Hydrocracked oils ≥ 90% ≤ 0.03% 80 ≤ VI < 120
Group III
Hydrocracked or
hydroisomerized oils
≥ 90% ≤ 0.03% ≥ 120
Group IV Poly-α-olefins (PAO)
Group V Esters and other bases not included in groups I to IV
17
The mineral base oils include all types of base oils obtained by atmospheric and vacuum
distillation of crude oil, followed by refining operations such as solvent extraction,
deasphalting, solvent deparaffinning, hydrotreating, hydrocracking, hydroisomerization and
hydrofinishing.
Mixtures of synthetic and mineral oils, which may be biobased, may also be used.
There is generally no limit as regards the use of different base oils for preparing the
compositions used according to the invention, other than the fact that they must have
properties, notably in terms of viscosity, viscosity index or resistance to oxidation, that are
suitable for use for the propulsion systems of an electric or hybrid vehicle.
The base oils of the compositions used according to the invention may also be chosen from
synthetic oils, such as certain esters of carboxylic acids and of alcohols, poly-α-olefins
(PAO) and polyalkylene glycols (PAG) obtained by polymerization or copolymerization of
alkylene oxides comprising from 2 to 8 carbon atoms, in particular from 2 to 4 carbon atoms.
The PAOs used as base oils are obtained, for example, from monomers comprising from 4
to 32 carbon atoms, for example from octene or decene. The weight-average molecular mass
of the PAO may vary quite broadly. Preferably, the weight-average molecular mass of the
PAO is less than 600 Da. The weight-average molecular mass of the PAO may also range
from 100 to 600 Da, from 150 to 600 Da or from 200 to 600 Da.
Advantageously, the base oil(s) of the composition used according to the invention are
chosen from poly-α-olefins (PAO), polyalkylene glycols (PAG) and esters of carboxylic
acids and of alcohols.
Preferably, the base oil(s) of the composition used according to the invention is(are) chosen
from group III, IV or V oils, and mixtures thereof, preferably it is a group III base oil.
According to an alternative embodiment, the base oil(s) of the composition used according
to the invention may be chosen from group II base oils.
It falls to a person skilled in the art to adjust the content of base oil to be used in a composition
that is suitable for use in the invention.
A lubricant composition under consideration according to the invention may comprise at
least 50% by mass of base oil(s) relative to its total mass, in particular from 60% to 99% by
mass of base oil(s).
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Additional additives
A lubricant composition that is suitable for use in the invention may also comprise any type
of additive, different from the additives of triazole type and from the amine-based and/or
sulfur-based antiwear additives defined in the context of the present invention, that are
suitable for use in a lubricant for a propulsion system of an electric or hybrid vehicle.
It is understood that the nature and amount of additives used are chosen so as not to affect
the properties in terms of antiwear and anticorrosion performance imparted by the
combination of said triazole compound(s) and of said amine-based and/or sulfur-based
additive(s) used according to the invention.
Such additives, which are known to a person skilled in the art in the field of the lubrication
and/or cooling of the propulsion systems of electric or hybrid vehicles, may be chosen from
friction modifiers, viscosity index modifiers, detergents, extreme-pressure additives,
dispersants, antioxidants, pour point depressants, antifoams and mixtures thereof.
Advantageously, a composition that is suitable for use in the invention comprises at least
one additional additive chosen from antioxidants, detergents, dispersants, pour point
depressant additives, antifoams, and mixtures thereof.
These additives may be introduced individually and/or in the form of a mixture such as those
already available for sale for commercial lubricant formulations for vehicle engines, with a
performance level as defined by the ACEA (Association des Constructeurs Européens
d’Automobiles) and/or the API (American Petroleum Institute), which are well known to
those skilled in the art.
A lubricant composition that is suitable for use in the invention may comprise at least one
friction-modifying additive. The friction-modifying additive may be chosen from a
compound providing metal elements and an ash-free compound. Among the compounds
providing metal elements, mention may be made of complexes of transition metals such as
Mo, Sb, Sn, Fe, Cu or Zn, the ligands of which may be hydrocarbon-based compounds
comprising oxygen, nitrogen, sulfur or phosphorus atoms. The ash-free friction-modifying
additives are generally of organic origin and may be chosen from fatty acid monoesters of
polyols, alkoxylated amines, alkoxylated fatty amines, fatty epoxides, borate fatty epoxides,
fatty amines or fatty acid esters of glycerol. According to the invention, the fatty compounds
comprise at least one hydrocarbon-based group comprising from 10 to 24 carbon atoms.
19
A lubricant composition that is suitable for use according to the invention may comprise
from 0.01% to 2% by weight or from 0.01% to 5% by weight, preferentially from 0.1% to
1.5% by weight or from 0.1% to 2% by weight of friction-modifying additive, relative to the
total weight of the composition.
A lubricant composition used according to the invention may comprise at least one
antioxidant additive.
The antioxidant additive generally makes it possible to retard the degradation of the
composition in service. This degradation may notably be reflected by the formation of
deposits, the presence of sludges, or by an increase in the viscosity of the composition.
The antioxidant additives notably act as free-radical inhibitors or hydroperoxide destroyers.
Among the commonly used antioxidant additives, mention may be made of antioxidant
additives of phenolic type, antioxidant additives of amine type and phospho-sulfur-based
antioxidant additives. Some of these antioxidant additives, for example the phospho-sulfurbased antioxidant additives, may be ash generators. The phenolic antioxidants additives may
be ash-free or may be in the form of neutral or basic metal salts. The antioxidants additives
may notably be chosen from sterically hindered phenols, sterically hindered phenol esters
and sterically hindered phenols comprising a thioether bridge, diphenylamines,
diphenylamines substituted with at least one C1-C12 alkyl group, N,N’-dialkyl-aryl-diamines,
and mixtures thereof.
Preferably according to the invention, the sterically hindered phenols are chosen from
compounds comprising a phenol group, in which at least one carbon vicinal to the carbon
bearing the alcohol function is substituted with at least one C1-C10 alkyl group, preferably a
C1-C6 alkyl group, preferably a C4 alkyl group, preferably with a tert-butyl group.
Amine compounds are another class of antioxidant additives that may be used, optionally in
combination with the phenolic antioxidants additives. Examples of amine compounds are
aromatic amines, for example the aromatic amines of formula NR4R
5R
6
in which R4
represents an optionally substituted aliphatic or aromatic group, R5
represents an optionally
substituted aromatic group, R6
represents a hydrogen atom, an alkyl group, an aryl group or
a group of formula R7S(O)zR
8
in which R7
represents an alkylene group or an alkenylene
group, R8
represents an alkyl group, an alkenyl group or an aryl group and z represents 0, 1
or 2.
20
Sulfurized alkylphenols or the alkali metal and alkaline-earth metal salts thereof may also
be used as antioxidant additives.
Another class of antioxidant additives is that of copper compounds, for example copper thioor dithio-phosphates, copper salts of carboxylic acids, and copper dithiocarbamates,
sulfonates, phenates and acetylacetonates. Copper I and II salts and succinic acid or
anhydride salts may also be used.
A lubricant composition used according to the invention may contain any type of antioxidant
additive known to those skilled in the art.
Advantageously, a lubricant composition used according to the invention comprises at least
one ash-free antioxidant additive.
A lubricant composition used according to the invention may comprise from 0.5% to 2% by
weight of at least one antioxidant additive, relative to the total weight of the composition.
According to a particular embodiment, a lubricant composition used according to the
invention is free of antioxidant additives of aromatic amine type or of sterically hindered
phenol type.
A lubricant composition that is suitable for use in the invention may also comprise at least
one detergent additive.
The detergent additives generally make it possible to reduce the formation of deposits on the
surface of metal parts by dissolving the oxidation and combustion byproducts.
The detergent additives that may be used in a lubricant composition used according to the
invention are generally known to those skilled in the art. The detergent additives may be
anionic compounds comprising a long lipophilic hydrocarbon-based chain and a hydrophilic
head. The associated cation may be a metal cation of an alkali metal or an alkaline-earth
metal.
The detergent additives are preferentially chosen from alkali metal or alkaline-earth metal
salts of carboxylic acids, sulfonates, salicylates and naphthenates, and also phenate salts.
The alkali metals and alkaline-earth metals are preferentially calcium, magnesium, sodium
or barium.
These metal salts generally comprise the metal in a stoichiometric amount or in excess, thus
in an amount greater than the stoichiometric amount. They are then overbased detergent
additives; the excess metal giving the overbased nature to the detergent additive is then
21
generally in the form of a metal salt that is insoluble in the oil, for example a carbonate, a
hydroxide, an oxalate, an acetate or a glutamate, preferentially a carbonate.
A lubricant composition that is suitable for use in the invention may comprise, for example,
from 2% to 4% by weight of detergent additive relative to the total weight of the
composition.
Also, a lubricant composition used according to the invention may comprise at least one
dispersant.
The dispersant may be chosen from Mannich bases, succinimides and derivatives thereof.
A lubricant composition used according to the invention may comprise, for example, from
0.2% to 10% by weight of dispersant, relative to the total weight of the composition.
According to a particular embodiment, a lubricant composition used according to the
invention is free of dispersant of succinimide type.
A lubricant composition that is suitable for use in the invention may also comprise at least
one antifoam.
The antifoam may be chosen from silicones.
A lubricant composition that is suitable for use in the invention may comprise from 0.01%
to 2% by mass or from 0.01% to 5% by mass, preferentially from 0.1% to 1.5% by mass or
from 0.1% to 2% by mass of antifoam, relative to the total weight of the composition.
A lubricant composition that is suitable for use in the invention may also comprise at least
one pour-point depressant (PPD).
By slowing down the formation of paraffin crystals, the pour-point depressant additives
generally improve the cold-temperature behavior of the composition. Examples of pourpoint depressant additives that may be mentioned include polyalkyl methacrylates,
polyacrylates, polyarylamides, polyalkylphenols, polyalkylnaphthalenes and
polyalkylstyrenes.
In particular, a lubricant composition used according to the invention may be free of
dispersant of succinimide type and of antioxidant additive of aromatic amine type or of
sterically hindered phenol type.
In terms of formulation of such a lubricant composition, said triazole compound(s) may be
added to a base oil or mixture of base oils, and the other additional additives, including the
amine-based and/or sulfur-based antiwear additive(s), are then added.
22
Alternatively, said triazole compound(s) may be added to a pre-existing conventional
lubricant formulation, notably comprising one or more base oils, one or more amine-based
and/or sulfur-based antiwear additives, and optionally additional additives.
Advantageously, a lubricant composition used according to the invention has a kinematic
viscosity, measured at 100°C according to the standard ASTM D445, ranging from 1 to
15 mm2
/s.
Advantageously, a lubricant composition used according to the invention has a kinematic
viscosity, measured at 40°C according to the standard ASTM D445, ranging from 3 to
80 mm2
/s.
According to an advantageous embodiment of the present invention, the electrical resistivity
values measured at 90°C for the lubricant compositions used according to the invention are
between 5 and 10 000 Mohm.m, more preferably between 6 and 5000 Mohm.m.
According to an advantageous embodiment of the present invention, the dielectric loss
values measured at 90°C for the lubricant compositions used according to the invention are
between 0.01 and 30, more preferably between 0.02 and 25 and more preferentially between
0.02 and 10.
Advantageously, a lubricant composition used according to the invention may be of a grade
according to the SAEJ300 classification defined by the formula (X)W(Y), in which X
represents 0 or 5, and Y represents an integer ranging from 4 to 20, in particular ranging
from 4 to 16 or from 4 to 12.
According to a particular embodiment, a lubricant composition used according to the
invention comprises, or even consists of:
- a base oil or mixture of base oils, preferably chosen from poly-α-olefins (PAO),
polyalkylene glycols (PAG) and esters of carboxylic acids and of alcohols;
- one or more anticorrosion additives of triazole type, preferably chosen from benzotriazole
derivatives, in particular tolyltriazole derivatives, and more preferentially those of formula
(IIa) indicated above;
- one or more amine-based and/or sulfur-based antiwear additives, preferably one or more
amine-based and sulfur-based antiwear additives, more preferentially chosen from
compounds of thia(di)azole type, in particular dimercaptothiazole derivatives as defined
above;
23
- optionally one or more additional additives chosen from antioxidants, detergents,
dispersants, pour point depressant additives, antifoams, and mixtures thereof.
Preferably, a lubricant composition used according to the invention comprises, or even
consists of:
- from 0.01% to 5% by mass, in particular from 0.1% to 3% by mass, and more particularly
from 0.5% to 2% by mass, of one or more anticorrosion additives of triazole type, preferably
chosen from benzotriazole derivatives, in particular tolyltriazole derivatives, and more
preferentially those of formula (IIa) indicated above;
- from 0.01% to 5% by mass, in particular from 0.1% to 3% by mass, and more particularly
from 0.5% to 2% by mass, of one or more amine-based and/or sulfur-based antiwear
additives, preferably one or more amine-based and sulfur-based antiwear additives, more
preferentially chosen from compounds of thia(di)azole type, in particular dimercaptothiazole
derivatives as defined above;
- from 60% to 99.9% by mass of base oil(s), preferably chosen from poly-α-olefins (PAO),
polyalkylene glycols (PAG) and esters of carboxylic acids and of alcohols, and mixtures
thereof;
- optionally from 0.01% to 5% by mass of one or more additives chosen from antioxidants,
detergents, dispersants, pour point depressant additives, antifoams, and mixtures thereof;
the contents being expressed relative to the total mass of said lubricant composition.
APPLICATION
As indicated previously, a lubricant composition that is suitable for use in the invention as
described previously is used as lubricant for a propulsion system of an electric or hybrid
vehicle, and more particularly for the motor and the power electronics.
Thus, the present invention relates to the use of a lubricant composition as defined
previously, combining one or more anticorrosion additives of triazole type, in particular as
defined previously, preferably tolyltriazole derivatives, and one or more amine-based and/or
sulfur-based antiwear additives, preferably dimercaptothiazole derivatives, for lubricating a
propulsion system of an electric or hybrid vehicle, in particular for lubricating the electric
motor and the power electronics of an electric or hybrid vehicle.
24
As represented schematically in Figure 1, the propulsion system of an electric or hybrid
vehicle notably comprises the electric motor part (1), an electric battery (2) and a
transmission, and in particular a speed reducer (3).
The electric motor typically comprises power electronics (11) connected to a stator (13) and
a rotor (14). The stator comprises coils, in particular copper coils, which are powered by an
alternating electric current. This makes it possible to generate a rotating magnetic field. For
its part, the rotor comprises coils, permanent magnets or other magnetic materials, and is
placed in rotation by the rotating magnetic field.
A rolling bearing (12) is generally incorporated between the stator (13) and the rotor (14). A
transmission, and in particular a speed reducer (3), makes it possible to reduce the rotation
speed at the outlet of the electric motor and to adapt the speed transmitted to the wheels,
making it possible simultaneously to control the speed of the vehicle.
The rolling bearing (12) is notably subjected to high mechanical stresses and poses problems
of wear by fatigue. It is thus necessary to lubricate the rolling bearing in order to increase its
service life. Also, the reducer is subject to high friction stresses and thus needs to be
appropriately lubricated in order to prevent it from being damaged too quickly.
Thus, the invention relates in particular to the use of a composition as described previously
for lubricating an electric motor of an electric or hybrid vehicle, in particular for lubricating
the rolling bearings located between the rotor and the stator of an electric motor.
The invention also relates to the use of a composition as described previously for lubricating
the transmission, in particular the reducer, in an electric or hybrid vehicle.
Advantageously, a composition according to the invention may thus be used for lubricating
the various parts of a propulsion system of an electric or hybrid vehicle, in particular the
rolling bearings located between the rotor and the stator of an electric motor, and/or the
transmission, in particular the reducer, in an electric or hybrid vehicle.
Advantageously, as mentioned previously, a lubricant composition according to the
invention has excellent antiwear and anticorrosion performance.
According to another of its aspects, the invention also relates to a process for lubricating at
least one part of a propulsion system of an electric or hybrid vehicle, in particular the rolling
bearings located between the rotor and the stator of an electric motor; and/or the
transmission, notably the reducer, comprising at least one step of placing at least said part in
contact with a composition as described previously.
25
The present invention thus proposes a process for simultaneously reducing the wear and
corrosion of at least one part of a propulsion system of an electric or hybrid vehicle, in
particular the rolling bearings located between the rotor and the stator of an electric motor;
and/or the transmission, notably the reducer, said process comprising at least one step of
placing at least said part in contact with a composition as described previously.
All of the features and preferences described for the composition used according to the
invention and for the uses thereof also apply to this process.
According to a particular embodiment, a composition according to the invention may have,
besides lubricating properties, good electrical insulation properties.
According to this embodiment, a composition according to the invention may
simultaneously be used for lubricating one or more parts of a propulsion system of an electric
or hybrid vehicle, in particular for lubricating the sensors and the solenoid valves of the
motor, the rolling bearings, but also the windings located in the rotor and the stator of an
electric motor, or else for lubricating the transmission, in particular the gears, the sensors,
the solenoid valves or the reducer which are found in an electric or hybrid vehicle, and for
electrically insulating at least one part of said propulsion system, notably the battery.
In the context of such an implementation variant, a lubricant composition under
consideration according to the invention advantageously has a kinematic viscosity, measured
at 100°C according to the standard ASTM D445, of between 2 and 8 mm²/s, preferably
between 3 and 7 mm²/s.
It is understood that the uses described above may be combined, a composition as described
previously possibly being used both as lubricant and as electrical insulator, but also as
coolant fluid for the motor, the battery and the transmission of an electric or hybrid vehicle.
According to the invention, the particular, advantageous or preferred features of the
composition according to the invention make it possible to define uses according to the
invention that are also particular, advantageous or preferred.
The invention will now be described by means of the examples that follow, which are,
needless to say, given as nonlimiting illustrations of the invention.
Example
Various compositions were evaluated:
- a composition C1 comprising an amine-based and sulfur-based antiwear additive of
dimercaptothiadiazole type free of anticorrosion additive;
26
- a composition C2 comprising said antiwear additive of dimercaptothiadiazole type and an
anticorrosion additive of triazole type, in accordance with the invention, of formula (IIa)
mentioned above:
2-ethyl-N-(2-ethylhexyl)-N-[(4-methylbenzotriazol-1-yl)methyl]hexan-1-amine;
- a composition C3 comprising said antiwear additive of dimercaptothiadiazole type and an
anticorrosion additive not in accordance with the invention, of alkylated organic acid ester
type;
- a composition C4 comprising said antiwear additive of dimercaptothiadiazole type and an
anticorrosion additive not in accordance with the invention, of N-acyl sarcosine type (Noleyl sarcosine); and
- a composition C5 comprising said antiwear additive of dimercaptothiadiazole type and an
anticorrosion additive not in accordance with the invention, of imidazoline derivative type.
Compositions C1 to C5 comprise, besides the abovementioned compounds, a group III base
oil.
The compositions and the amounts (expressed as mass percentages) are indicated in Table 2
below.
[Table 2]
C1 C2 C3 C4 C5
Base oil 99% 98% 98% 98% 98%
Dimercaptothiadiazole
antiwear agent 1% 1% 1% 1% 1%
Tolyltriazole
derivative
anticorrosion agent
- 1% -
- -
Alkylated organic acid
ester anticorrosion
agent
- - 1%
- -
N-oleyl sarcosine
anticorrosion agent - - -
1% -
Imidazoline derivative
anticorrosion agent - - -
- 1%
Evaluation of the anticorrosion properties
Evaluation method
The corrosive (or corroding) power of a composition may be evaluated by means of a test
involving study of the variation in the electrical resistance value of a copper wire of a
preestablished diameter, as a function of the duration of immersion of this wire in the
27
composition. The variation in this electrical resistance value is directly correlated with the
variation in the diameter of the test wire. In the context of the present invention, the diameter
of the wire chosen is 70 µm.
In the present case, a copper wire is immersed in a test tube containing 20 mL of a test
composition (composition C2 being a composition according to the invention and
compositions C1 and C3 to C5 being compositions serving as a comparative).
The resistance of the wire is measured using an ohmmeter.
The measuring current is 1 mA.
The temperature of the test composition is brought to 150°C.
The resistance of the copper wire is calculated by this equation (1):
[Math 1]
𝑅 = 𝜌 ×
𝐿
𝑆
in which R is the resistance, ρ is the resistivity of copper, L is the length of the wire and S is
the cross-sectional area.
In this equation (1), ρ and L are constants. Thus, the resistance R is inversely proportional
to the cross-sectional area of the immersed wire.
The diameter of the wire is calculated from the cross-sectional area (equation (2)):
[Math 2]
𝑆 =
𝜋
4
× 𝐷
ଶ
in which D is the diameter of the wire.
Equation (2) is inserted into equation (1) to obtain the relationship between the resistance
and the diameter (equation (3)):
[Math 3]
𝑅 = 𝜌 ×
𝐿
𝜋
4
× 𝐷ଶ
Thus, when the wire is corroded by the test compositions, the diameter of the wire decreases,
thus bringing about an increase in the resistance value.
By monitoring the resistance, it is possible to monitor the change in the diameter of the wire,
which reflects the state of corrosion suffered by the immersed wire.
The loss of diameter of the wire is thus calculated directly from the measured resistance.
28
When the measured resistance is infinite, this is an open circuit. The wire has thus broken,
which defines very severe corrosion.
Results
The results are summarized in the following table 3 and are expressed in µm (loss of
diameter). The lower the value obtained, the better the anticorrosion properties of the
composition evaluated.
A composition is considered to be “noncorrosive” when the loss of diameter of the copper
wire studied is less than or equal to 0.5 µm after immersion for 80 hours, in particular less
than or equal to 0.1 µm after immersion for 20 hours in the composition.
[Table 3]
Compositions C1 C2 C3 C4 C5
Loss of
diameter (in
µm) at 30
hours
1.00 0.17 0.55 0.88 Broken wire
Loss of
diameter (in
µm) at 50
hours
Broken wire 0.23 Broken wire 2.00 Broken wire
Loss of
diameter (in
µm) at 80
hours
Broken wire 0.43 Broken wire Broken wire Broken wire
It emerges from these results that the addition of a triazole compound in a lubricant
composition also comprising at least one amine-based and/or sulfur-based antiwear additive
makes it possible to achieve significantly improved anticorrosion properties compared with
lubricant compositions free of triazole compounds or comprising anticorrosion additives
different from triazole compounds.
29
We Claim:
1. The use of at least one triazole compound, as an additive for improving the
anticorrosion properties of a lubricant composition intended for a propulsion system of an
electric or hybrid vehicle and comprising one or more amine-based and/or sulfur-based
antiwear additives.
2. The use as claimed in claim 1, in which the triazole compound is chosen
from optionally substituted triazoles, in particular 1,2,3-triazole; benzotriazoles and
derivatives thereof; and mixtures thereof, preferably it is a benzotriazole derivative, more
preferentially a tolyltriazole derivative.
3. The use as claimed in either of the preceding claims, in which the triazole
compound is a tolyltriazole derivative of formula (IIa) below:
in which:
R4
and R5
represent, independently of each other, a hydrogen atom, a linear or branched,
preferably branched, C3 to C14, preferably C6 to C12, alkyl group; and
-A- represents a linear or branched, preferably linear, C1 to C6, preferably C1 to C3, alkylene
group and more preferentially a methylene group (-CH2-);
in particular, said tolyltriazole derivative being 2-ethyl-N-(2-ethylhexyl)-N-[(4-
methylbenzotriazol-1-yl)methyl]hexan-1-amine.
4. The use as claimed in any one of the preceding claims, in which the aminebased and/or sulfur-based antiwear additive is chosen from additives of thia(di)azole type,
in particular dimercaptothiadiazole derivatives; polysulfide additives, notably sulfur-based
olefins; amine phosphates; phospho-sulfur additives such as alkylthiophosphates; and
mixtures thereof.
30
5. The use as claimed in any one of the preceding claims, in which the aminebased and/or sulfur-based antiwear additive is chosen from dimercaptothiadiazole
derivatives, in particular the 2,5-dimercapto-1,3,4-thiadiazole derivatives having the
following formulae, taken alone or as a mixture:
in which the group(s) R1 represent, independently of each other, hydrogen atoms,
linear or branched alkyl or alkenyl groups comprising from 1 to 24, preferably from 2 to 18,
more preferentially from 4 to 16 and even more preferentially from 8 to 12 carbon atoms or
aromatic substituents, n being, independently of each other, integers equal to 1, 2, 3 or 4, n
preferably being equal to 1.
6. The use as claimed in any one of the preceding claims, in which said triazole
compound(s) is(are) present in a content ranging from 0.01% to 5% by mass, in particular
from 0.1% to 3% by mass, and more particularly from 0.5% to 2% by mass, relative to the
total mass of the lubricant composition; and/or said amine-based and/or sulfur-based
antiwear additive(s) is(are) present in a content ranging from 0.01% to 5% by mass, in
particular from 0.1% to 3% by mass, and more particularly from 0.5% to 2% by mass,
relative to the total mass of the lubricant composition.
7. The use as claimed in any one of the preceding claims, in which said aminebased and/or sulfur-based antiwear additive is a 2,5-dimercapto-1,3,4-thiadiazole derivative
and said triazole compound is a tolyltriazole derivative, in particular 2-ethyl-N-(2-
ethylhexyl)-N-[(4-methylbenzotriazol-1-yl)methyl]hexan-1-amine.
8. The use of a lubricant composition comprising one or more anticorrosion
additives of triazole type and one or more amine-based and/or sulfur-based antiwear
31
additives, for lubricating a propulsion system of an electric or hybrid vehicle, in particular
for lubricating the electric motor and the power electronics of an electric or hybrid vehicle.
9. The use as claimed in the preceding claim, in which the anticorrosion
additive(s) of triazole type are as defined in any one of claims 2, 3, 6 and 7; and/or the aminebased and/or sulfur-based antiwear additive(s) are as defined in any one of claims 4 to 7.
10. The use as claimed in claim 8 or 9, for lubricating the rolling bearings
located between the rotor and the stator of an electric motor, and/or the transmission, in
particular the reducer, of an electric or hybrid vehicle.