Aqueous composition for lubricating and / or cooling a propulsion system of an electric or hybrid vehicle
Patent Information
- Application Number
- EP2023720569
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-04-20
- Filing Date
- 2023-04-18
- Publication Date
- 2025-02-26
Smart Images
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Abstract
Description
[0001] Description
[0002] Title: Aqueous composition for the lubrication and / or cooling of a propulsion system of an electric or hybrid vehicle
[0003] Technical field
[0004] The present invention relates to the field of lubricating compositions intended for a propulsion system of an electric or hybrid vehicle. It aims more particularly to provide a water-based lubricating composition, provided with both lubricating and cooling properties with respect to the various components of a propulsion system of an electric or hybrid vehicle, such as the transmission, the engine and the battery.
[0005] Prior art
[0006] The evolution of international standards for reducing CO2 emissions, but also for reducing energy consumption, is pushing car manufacturers to offer alternative solutions to combustion engines.
[0007] One solution identified by car manufacturers is to replace combustion engines with electric motors. Research into reducing CO2 emissions has therefore led to the development of electric or hybrid vehicles by several car companies.
[0008] For the purposes of the present invention, the term "electric vehicle" means a vehicle comprising an electric motor as the sole means of propulsion and, by "hybrid vehicle", a vehicle which comprises a combustion engine and an electric motor as combined means of propulsion.
[0009] For the purposes of the present invention, the term "propulsion system" means a system comprising the mechanical parts necessary for the propulsion of an electric vehicle. The propulsion system thus more particularly includes an electric motor, the rotor-stator assembly of the power electronics (dedicated to speed regulation), a transmission and a battery.
[0010] Generally speaking, it is necessary to implement, in electric or hybrid vehicles, compositions to meet the dual constraint of lubrication and cooling of the various parts of the propulsion system mentioned above. On the one hand, lubricating compositions, also called "lubricants", are commonly implemented in engines for the purpose of reducing friction forces between the various moving metal parts in the engines, and thus protecting the parts against wear. In addition to wear phenomena, friction can oppose the relative movement of the parts in contact and induce energy losses that are detrimental to optimal operation of the propulsion system.
[0011] To do this, a lubricating composition is classically composed of one or more base oils, to which are generally associated several additives dedicated to stimulating the lubricating performance of the base oils, such as for example friction modifying additives.
[0012] Furthermore, electric propulsion systems generate heat during operation via the electric motor, power electronics and batteries. Since the amount of heat generated is greater than the amount of heat normally dissipated to the environment, it is necessary to ensure cooling of the motor, power electronics and batteries. Generally, cooling is carried out on several parts of the propulsion system generating heat and / or the parts of said system sensitive to heat, in order to avoid reaching dangerous temperatures, and in particular the power electronics and batteries. This cooling is typically provided by a cooling fluid, distinct from the hydrocarbon lubricant, such as air, an aqueous fluid, such as water or a mixture of water and a glycol.
[0013] For obvious reasons of economy and ease of implementation, it would be advantageous to have a composition that could simultaneously meet the lubrication and cooling needs of a propulsion system of an electric or hybrid vehicle.
[0014] The most common lubricants are hydrocarbon-based lubricants. However, these hydrocarbon oils generally do not provide sufficient heat dissipation to allow their joint use as coolants.
[0015] More recently, and in response to a growing demand to avoid the use of toxic solvents and reduce the environmental impact of products, studies have focused on the development of water-based lubricants. While water is an excellent cooling fluid, it does not, however, have the tribological properties required for a lubricant, particularly in terms of friction reduction and protection of parts against wear. Additive systems have been proposed to give the aqueous fluid satisfactory lubrication performance.
[0016] For example, application WO 2021 / 259853 has described an aqueous lubricating composition comprising a polyalkylene glycol, an antifreeze compound and a phosphorus compound. However, this aqueous lubricant is not entirely satisfactory, in particular with regard to the phenomenon of pitting due to mechanical fatigue that it is likely to cause. Indeed, it has been observed that this lubricating composition can generate this type of failure in mechanical contacts, in particular depending on the formulation protocol of the composition.
[0017] Statement of the invention
[0018] The present invention aims specifically to propose a new aqueous-based composition, having tribological and cooling properties, suitable for its use for the lubrication and / or cooling of an electric or hybrid vehicle propulsion system, while reducing, or even eliminating, pitting phenomena due to mechanical fatigue.
[0019] More particularly, the present invention relates, according to a first of its aspects, to the use, for cooling and / or lubricating a propulsion system of an electric or hybrid vehicle, in particular of an electric vehicle, of an aqueous lubricating composition comprising at least:
[0020] - water, preferably deionized water; and
[0021] - at least one polyalkylene glycol; said aqueous lubricating composition comprising a content of phosphate ester salt(s), in particular chosen from alkali metal salts of phosphate esters, strictly less than 0.1% by mass, relative to the total mass of said composition.
[0022] Preferably, an aqueous lubricating composition according to the invention comprises less than 0.05% by mass, in particular less than 0.01% by mass, of phosphate ester salt(s), in particular chosen from alkali metal salts of phosphate esters, or even is completely free of phosphate ester salts.
[0023] Advantageously, the aqueous lubricating composition according to the invention comprises less than 0.1% by mass of sulfur-containing fatty acid(s), preferably less than 0.01% by mass, in particular is completely free of sulfur-containing fatty acid.
[0024] For the purposes of the present invention, the term "aqueous composition" is intended to denote a composition comprising water as the base fluid, in other words as the major solvent. The water, preferably deionized, advantageously represents more than 35% by mass, in particular more than 40% by mass, and in particular more than 50% by mass, of the total mass of the lubricating composition.
[0025] In the remainder of the text, the term "aqueous lubricating composition" or "aqueous lubricant" will refer to a lubricating composition required according to the invention as defined above and detailed in the remainder of the text. Due to its cooling properties, such a composition may also be referred to as an "aqueous cooling composition" or "aqueous cooling composition".
[0026] Advantageously, a lubricating composition used according to the invention, formed mainly of water, has little toxicological impact, particularly for people using this lubricant.
[0027] Furthermore, even if water is the main solvent, a composition according to the invention has good properties in terms of lubrication.
[0028] Thus, an aqueous lubricating composition according to the invention advantageously combines good cooling properties linked to the presence of water, and good tribological properties, in particular friction reduction and wear resistance. Thus, an aqueous composition according to the invention can ensure the dual function of lubrication and cooling of the engine system of the electric or hybrid vehicle, in particular the electric motor, the power electronics, the transmission and / or the battery of an electric or hybrid vehicle.
[0029] The invention thus relates, according to another of its aspects, to a method for lubricating and / or cooling a propulsion system of an electric or hybrid vehicle comprising at least one step of bringing at least one mechanical part of said propulsion system into contact with an aqueous lubricating composition as defined above. Thus, an aqueous composition according to the invention advantageously makes it possible to dispense with the use of two separate fluids, on the one hand a cooling fluid, on the other, a lubricating fluid.
[0030] In particular, an aqueous lubricating composition according to the invention makes it possible to ensure effective cooling of the engine, the power electronics and the battery, as well as the lubrication of the electric motor, the transmission, in particular the reducer, in an electric or hybrid vehicle.
[0031] In particular, an aqueous lubricating composition according to the invention can be used to lubricate and / or cool the reducer and / or the motor and / or the power electronics of an electric vehicle.
[0032] Also, as illustrated in the examples which follow, the inventors have discovered that an aqueous lubricant according to the invention as described previously, in particular in which the content of phosphate ester salt(s), if present, remains strictly less than 0.1% by mass, makes it possible to reduce, or even eliminate, the phenomena known as pitting by mechanical fatigue (or "pitting" in English terminology).
[0033] An aqueous lubricating composition according to the invention thus proves to be suitable for use in the lubrication and / or cooling of propulsion systems of electric or hybrid vehicles, but also for reducing pitting due to mechanical fatigue in these systems.
[0034] The present application thus relates to the use of an aqueous lubricating composition intended to lubricate and / or cool a propulsion system of an electric or hybrid vehicle, comprising at least:
[0035] - water, preferably deionized water; and
[0036] - at least one polyalkylene glycol; said aqueous lubricating composition comprising a content of phosphate ester salt(s), in particular chosen from alkali metal salts of phosphate esters, strictly less than 0.1% by mass, relative to the total mass of the composition, to reduce pitting by mechanical fatigue of the mechanical part(s) of said propulsion system brought into contact with said composition. The invention also relates, according to another of its aspects, to an aqueous lubricating composition for the lubrication and / or cooling of an electric or hybrid propulsion system, comprising at least:
[0037] - at least 45% by mass of water, in particular at least 50% by mass of water, preferably deionized water, relative to the total mass of the composition; and
[0038] - at least one polyalkylene glycol; said aqueous lubricating composition comprising a content of phosphate ester salt(s), in particular chosen from alkali metal salts of phosphate esters, strictly less than 0.1% by mass, relative to the total mass of the composition.
[0039] Furthermore, an aqueous lubricating composition according to the invention advantageously makes it possible to act effectively on fuel consumption via its impact on the friction forces generated between the various components of hybrid vehicles. In particular, an aqueous lubricating composition proves to be particularly advantageous for reducing friction in gearboxes, in axle differentials and / or in the cylinder head. By thus reducing friction between moving parts in the vehicle's propulsion system, a lubricating composition according to the invention not only makes it possible to reduce wear, but also to limit energy losses responsible for excess fuel consumption.
[0040] An aqueous lubricating composition according to the invention thus advantageously has good properties in terms of reducing the fuel consumption of hybrid vehicles, also known as “Fuel Eco” properties.
[0041] The invention thus relates, according to another of its aspects, to the use of an aqueous lubricating composition according to the invention for reducing the fuel consumption of a combustion engine of a hybrid vehicle lubricated using this composition, or of a hybrid vehicle equipped with a transmission, in particular an axle or a gearbox, said transmission being lubricated using this composition.
[0042] Other characteristics, variants and advantages of an aqueous lubricating composition according to the invention and of its implementation for lubricating and / or cooling a propulsion system of an electric or hybrid vehicle will become more apparent upon reading the description and examples which follow, given for illustrative and non-limiting purposes of the invention. The expressions "between ... and ...", "ranging from ... to ...", "formed from ... to ...", and "varying from ... to ...", must be understood inclusively, unless otherwise stated.
[0043] In the description and examples, unless otherwise indicated, percentages are by weight. Percentages are therefore expressed by mass relative to the total mass of the composition. Temperature is expressed in degrees Celsius unless otherwise indicated, and pressure is atmospheric pressure unless otherwise indicated.
[0044] Brief description of the drawings
[0045] [Fig 1] schematically represents a propulsion system of an electric or hybrid vehicle.
[0046] Detailed description
[0047] AQUEOUS COMPOSITION
[0048] As mentioned previously, an aqueous lubricating composition used according to the invention, also called aqueous lubricant, is a formulation comprising water as the majority solvent.
[0049] For the purposes of the invention, the term "majority solvent" is understood to mean that water is present in a greater quantity than any other solvent possibly present in the composition. Preferably, an aqueous lubricating composition according to the invention comprises at least 20% by mass of water, in particular deionized water, preferably at least 30% by mass, in particular between 35% and 90% by mass, more preferably between 40% and 75% by mass, in particular between 40 and 60% by mass, relative to the total mass of the composition.
[0050] According to one embodiment, an aqueous lubricating composition according to the invention comprises at least 45% by mass, in particular at least 50% by mass of water, in particular deionized water, preferably between 50% and 90% by mass, more preferably between 50% and 75% by mass of water, in particular between 50 and 60% by mass of water, relative to the total mass of the composition.
[0051] Advantageously, in addition to its role as a solvent, water provides access to a lubricating composition having good cooling properties, and which can be used as a cooling fluid for the various components in an electric or hybrid vehicle propulsion system. For the purposes of the present invention, the term "cooling fluid" is intended to denote a fluid capable of dissipating the heat generated by a propulsion system of an electric or hybrid vehicle. More specifically, such a fluid is characterized by an increased heat absorption capacity when it comes into contact with a heating part.
[0052] According to a particular embodiment, the water used in an aqueous lubricating composition required according to the invention is demineralized or osmosed water, in particular deionized water.
[0053] For the purposes of the present invention, the term “osmosed water” is intended to denote water that has undergone purification, in particular by a reverse osmosis process, in order to reduce the content of organic and / or mineral compounds, for example to a content of less than 5.0% by weight, preferably less than 1.0% by weight. In the remainder of the text, the expressions “demineralized water” or “ultrapure water” will be considered equivalent or synonymous with the expression “osmosed water”. In particular, osmosed water may be “deionized water”, in other words water that has undergone purification in order to reduce the content of ions, such as Ca ions. 2+ and HCO3' generally present in water. Preferably deionized water does not contain ions.
[0054] The use of deionized water is therefore particularly advantageous in the context of the use of the aqueous lubricant according to the invention for the components of the propulsion system of an electric or hybrid vehicle requiring a fluid that conducts little, or even no, electricity, such as for example the electric motor or the battery.
[0055] An aqueous lubricating composition used according to the invention differs from lubricants conventionally used in vehicle propulsion systems, which comprise a majority proportion of one or more base oils which are not soluble in water.
[0056] "Water-insoluble oil" means, in particular, an oil that does not dissolve substantially in water at room temperature (at about 25°C). In particular, a water-insoluble oil has a solubility in water of less than 0.2 g / L at room temperature.
[0057] These include lubricating base oils belonging to groups I to V according to the classes defined in the API classification (or their equivalents according to the ATIEL classification) and mixtures thereof. Preferably, an aqueous lubricating composition used according to the present invention comprises less than 5% by mass of base oil(s) not soluble in water, preferably less than 2% by mass, more preferably less than 1% by mass, relative to the total mass of the composition.
[0058] Advantageously, an aqueous lubricating composition used according to the invention is completely free of oil which is not soluble in water.
[0059] POLYALKYLENE GLYCOL
[0060] As indicated previously, an aqueous lubricating composition implemented according to the invention comprises at least one polyalkylene glycol.
[0061] Polyalkylene glycols (denoted “PAG”) are chosen from water-soluble polyalkylene glycols.
[0062] By "water soluble" is meant a polyalkylene glycol having a water solubility of at least 10 g / L, preferably at least 500 g / L, in water at room temperature (about 25°C).
[0063] The polyalkylene glycols may be more particularly formed from C1-C4, preferably C1-C3, more particularly C2-C3, alkylene oxide units.
[0064] Advantageously, a polyalkylene glycol used in an aqueous lubricating composition required according to the invention comprises at least 50% by mass, in particular at least 80% by mass, more preferably at least 90% by mass of propylene oxide and / or ethylene oxide units. It may be a copolymer, optionally random, of ethylene oxide / propylene oxide.
[0065] Preferably, a polyalkylene glycol used in an aqueous lubricating composition according to the invention has a weight-average molecular mass (Mw) of between 100 and 50,000 g. mol' 1 , preferably between 5,000 and 25,000 g.moL 1 .
[0066] Weight average molecular mass can be measured by gel permeation chromatography (GPC).
[0067] Preferably, a polyalkylene glycol used in an aqueous lubricating composition according to the invention has a kinematic viscosity measured at 100°C (KV100), according to standard ASTM D445, of between 100 and 25,000 mm 2 / s, especially between 150 and 10,000 mm 2 / s. Preferably, a polyalkylene glycol used in an aqueous lubricating composition according to the invention has a kinematic viscosity measured at 40°C (KV40), according to standard ASTM D445, of between 500 and 100,000 mm 2 / s, more particularly between
[0068] I 000 and 95 000 mm 2 / s.
[0069] The flash point of a polyalkylene glycol used in an aqueous lubricating composition according to the invention is preferably greater than or equal to 160°C, in particular greater than or equal to 220°C. The flash point can be measured by the ISO 2592 or ASTM D92 standard.
[0070] Preferably, a polyalkylene glycol used in an aqueous lubricating composition according to the invention has a viscosity index measured according to standard ASTM D2270, between 100 and 800, preferably between 250 and 550.
[0071] In particular, said polyalkylene glycol compound(s) may be used in an aqueous lubricating composition required according to the invention in a content of at least 5.0% by mass, preferably between 5.0% and 50% by mass, more preferably between 10% and 40% by mass, in particular between 10% and 20% by mass, relative to the total mass of the composition.
[0072] Preferably, an aqueous lubricating composition used according to the invention comprises less than 17% of polyalkylene glycol compound(s), more preferably between 10% and 15% by mass of polyalkylene glycol compound(s).
[0073] It is understood that an aqueous lubricating composition used according to the invention may comprise a single polyalkylene glycol or a mixture of several different polyalkylene glycols.
[0074] In particular, an aqueous lubricating composition according to the invention may comprise a mixture of at least two distinct polyalkylene glycols, more particularly at least one polyalkylene glycol of low weight average molecular mass and at least one polyalkylene glycol of high weight average molecular mass.
[0075] It is within the general skills of a person skilled in the art to adjust the nature and content of low and high weight-average molecular weight polyalkylene glycols in the polyalkylene glycol mixture, particularly with regard to the viscosity targeted for the final lubricating composition. The combination of at least one low weight-average molecular weight polyalkylene glycol and at least one high weight-average molecular weight polyalkylene glycol is particularly advantageous in order to obtain good solubilization of the various compounds introduced into the aqueous lubricating composition.
[0076] According to an alternative embodiment, it is possible to use, alternatively to the polyalkylene glycol(s) or in conjunction with them, one or more vinylpyrrolidone polymer(s).
[0077] By "polymer" is meant, in the broad sense, both homopolymers of vinylpyrrolidone and copolymers formed from vinylpyrrolidone and one or more other monomers.
[0078] Thus, more generally, an aqueous lubricating composition used according to the invention may comprise one or more vinylpyrrolidone polymer(s), in particular chosen from polyvinylpyrrolidones (denoted PVPs).
[0079] Polyvinylpyrrolidones correspond more specifically to the following formula: in which n represents the average number of constituent units of the polymer.
[0080] Such compounds may be synthesized by any method known to those skilled in the art, in particular by polymerization of N-vinylpyrrolidone, and may also be commercially available.
[0081] Polyvinylpyrrolidones more particularly suitable for the invention have a weight-average molecular mass (Mw) of between 20,000 and 50,000 g.mol' 1 , preferably between 25,000 and 45,000 g.mol' 1 .
[0082] In particular, said vinylpyrrolidone polymer(s), in particular chosen from polyvinylpyrrolidones, may be present in an aqueous lubricating composition according to the invention in a content of at least 5.0% by mass, preferably between 5.0% and 50% by mass, more preferably between 10% and 40% by mass, in particular between 10% and 20% by mass, relative to the total mass of the composition. ADDITIVES
[0083] Phosphorus compounds
[0084] As indicated previously, the content of phosphorus compound(s) of the phosphate ester salt type, if present, in an aqueous lubricating composition used according to the invention, is strictly less than 0.1% by mass, relative to the total mass of the composition.
[0085] Generally speaking, a “phosphorus compound” within the meaning of the present invention is intended to denote a compound comprising at least one phosphorus atom. Preferably, such phosphorus compounds do not provide sulfur.
[0086] Said phosphorus compound(s) may be used in aqueous compositions in a form soluble or emulsifiable in water, in particular in the form of ionic salts.
[0087] Examples of phosphate ester salts include salts of alkyl, alkenyl or aryl phosphate esters, in particular of C 1 -C 8 alkyl or dialkyl phosphate esters. These salts are in particular in the form of phosphate ions neutralized by a suitable counterion.
[0088] The salts may be salts of alkali or alkaline earth metals, ammonium, alkanolamines, especially C2-C8, or alkaneamines, especially C2-C8 of phosphate esters.
[0089] Advantageously, the phosphate ester salt(s) are alkali metal salts of phosphate esters.
[0090] When the aqueous lubricating composition according to the invention comprises one or more phosphate ester salts, for example as described above, these are used in a content strictly less than 0.1% by mass, relative to the total mass of said composition.
[0091] Advantageously, an aqueous lubricating composition used according to the invention comprises less than 0.05% by mass of phosphate ester salt(s), in other words comprises a content of phosphate ester salt(s) ranging from 0.0% to 0.05% by mass, in particular less than 0.01% by mass and more particularly less than 0.001% by mass, relative to the total mass of composition. According to a particularly preferred embodiment, an aqueous lubricating composition used according to the invention is completely free of phosphate ester salts.
[0092] An aqueous lubricating composition used according to the invention may comprise one or more other phosphorus compounds distinct from the phosphate ester salts, called “additional phosphorus compound(s)”.
[0093] Examples of related phosphorus compounds include amine phosphates; polyphosphates; phosphonates such as phosphonate esters, particularly alkyl, alkenyl or aryl phosphonates; polyphosphonates; carbamyl phosphates; phosphinates; and mixtures thereof.
[0094] These may be in the form of salts, particularly in the form of phosphonate or phosphinate ions neutralized by a suitable counterion.
[0095] The salts may be salts of alkali or alkaline earth metals, ammonium, alkanolamines, especially C2-C8, or alkaneamines, especially C2-C8, phosphonate or phosphinate.
[0096] When the aqueous lubricating composition according to the invention comprises one or more additional phosphorus compound(s), for example as described above, these may be used in a content ranging from 0.01% to 5.0% by mass, in particular ranging from 0.1% to 3.0% by mass, relative to the total mass of composition.
[0097] According to one embodiment, when the aqueous lubricating composition according to the invention comprises one or more additional phosphorus compound(s), in particular as described above, these are used in a content strictly less than 0.1% by mass, relative to the total mass of said composition.
[0098] Advantageously, the overall content of phosphorus compound(s), including phosphate ester salts or any other additional phosphorus compound, may be strictly less than 0.1% by mass, relative to the total mass of said composition, in particular less than 0.05% by mass.
[0099] In other words, an aqueous lubricating composition used according to the invention preferably comprises a content of phosphorus compound(s) strictly less than 0.1% by mass, in particular ranging from 0.0% to 0.05% by mass, in particular less than 0.01% by mass and more particularly less than 0.001% by mass, relative to the total mass of the composition.
[0100] Thus, according to one embodiment, an aqueous lubricating composition used according to the invention comprises at least:
[0101] - water, preferably deionized water;
[0102] - at least one polyalkylene glycol; and said aqueous lubricating composition comprising a content of phosphorus compound(s) strictly less than 0.1% by mass, in particular ranging from 0.0% to 0.05% by mass, in particular less than 0.01% by mass and more particularly less than 0.001% by mass, relative to the total mass of the composition,
[0103] According to a particularly preferred embodiment, an aqueous lubricating composition used according to the invention is completely free of phosphorus compound.
[0104] According to a particular embodiment, an aqueous lubricating composition required according to the invention may comprise a phosphorus content of less than or equal to 0.05% by mass, in particular less than or equal to 0.02% by mass and more particularly less than or equal to 0.01% by mass. The phosphorus content may be measured by ICP (for "Inductively Coupled Plasma" in English). Advantageously, an aqueous lubricating composition required according to the invention is completely free of phosphorus.
[0105] Antifreeze compound
[0106] An aqueous lubricating composition used according to the invention may comprise at least one antifreeze compound chosen from glycols, preferably alkylene glycols; glycerol; diglycerol; triglycerol, and mixtures thereof.
[0107] Thus, according to a preferred embodiment, an aqueous lubricating composition used according to the invention comprises at least:
[0108] - water, preferably deionized water;
[0109] - at least one polyalkylene glycol; and
[0110] - at least one antifreeze compound chosen from glycols, preferably alkylene glycols; glycerol; diglycerol; triglycerol, and mixtures thereof; said aqueous lubricating composition comprising a content of phosphate ester salt(s), in particular chosen from alkali metal salts of phosphate esters, strictly less than 0.1% by mass, relative to the total mass of the composition, preferably being free of phosphate ester salts.
[0111] These compounds are known for their antifreeze action, in other words for reducing the freezing temperature of the composition.
[0112] Glycols are diols in which the two hydroxyl groups are carried by different carbon atoms, preferably by vicinal carbon atoms.
[0113] Preferably, the glycols are alkylene glycols, in particular having from 2 to 10 carbon atoms, in particular from 2 to 6 carbon atoms. Examples that may be mentioned are monoethylene glycol, diethylene glycol and propylene glycol.
[0114] The antifreeze compound may further be chosen from glycerol, diglycerol, triglycerol and mixtures thereof.
[0115] Preferably, the antifreeze compound used according to the invention is chosen from monoethylene glycol, diethylene glycol, propylene glycol, glycerol and mixtures thereof. Preferably, the antifreeze compound is diethylene glycol.
[0116] In particular, said antifreeze compound(s), in particular as defined above, for example diethylene glycol, may be used in an aqueous lubricating composition according to the invention in a content of at least 1.0% by mass, preferably between 5.0% and 50% by mass, more preferably between 10% and 45% by mass, in particular between 20% and 40% by mass, relative to the total mass of the composition.
[0117] Preferably, an aqueous lubricating composition used according to the invention comprises a content of antifreeze compound(s), in particular as defined above, for example diethylene glycol, greater than or equal to 33%, in particular between 33.5% and 40% by mass, relative to the total mass of said composition.
[0118] According to a particular embodiment, the invention relates to the use, for cooling and / or lubricating a propulsion system of an electric or hybrid vehicle, of an aqueous lubricating composition comprising at least:
[0119] - water;
[0120] - at least one polyalkylene glycol; and - at least one antifreeze compound chosen from glycols in a content greater than or equal to 33% by mass, relative to the total mass of the composition; said aqueous lubricating composition comprising a content of phosphate ester salt(s), in particular chosen from alkali metal salts of phosphate esters, strictly less than 0.1% by mass, relative to the total mass of said composition.
[0121] According to a particular embodiment, the invention relates to an aqueous lubricating composition for the lubrication and / or cooling of an electric or hybrid propulsion system, comprising at least:
[0122] - at least 45% by mass of water, relative to the total mass of the composition;
[0123] - at least one polyalkylene glycol; and
[0124] - at least one antifreeze compound chosen from glycols in a content greater than or equal to 33% by mass, relative to the total mass of the composition; said aqueous lubricating composition comprising a content of phosphate ester salt(s), in particular chosen from alkali metal salts of phosphate esters, strictly less than 0.1% by mass, relative to the total mass of said composition.
[0125] According to a particular embodiment, an aqueous lubricating composition used according to the invention comprises at least:
[0126] - at least 35% by mass of water, in particular deionized water, preferably 40 to 60% by mass of water; in particular 45 to 60% by mass of water;
[0127] - at least 10% by mass, in particular between 10 and 20% by mass, of at least one polyalkylene glycol, in particular as defined above;
[0128] - at least 5.0% by mass, in particular between 20 and 40% by mass, of at least one antifreeze compound chosen from glycols, preferably alkylene glycols; glycerol; diglycerol; triglycerol, and mixtures thereof, said antifreeze compound preferably being diethylene glycol.
[0129] According to a particular embodiment, the assembly consisting of water, said polyalkylene glycol(s), and optionally said antifreeze compound(s) represent more than 90% of the total mass of said aqueous lubricating composition, in particular more than 95%, in particular more than 96%, or even more than 97%, of the total mass of said aqueous lubricating composition. Other additives
[0130] An aqueous lubricating composition according to the invention may further comprise various additives.
[0131] It is understood that the said additive(s) are compatible with their use in an aqueous medium. Advantageously, the additives are used in a form that is soluble or emulsifiable in water, for example in the form of salts or ionic liquids.
[0132] The said additive(s) are of course chosen with regard to the intended application for the aqueous lubricant.
[0133] Of course, the person skilled in the art will take care to choose the possible additives and / or their quantity in such a way that the advantageous properties of the aqueous lubricating composition according to the invention, in particular the properties in terms of reduction of pitting by mechanical fatigue, and of cooling, are not altered by the envisaged addition.
[0134] Such additives may be more particularly chosen from anti-foaming agents, biocides, pH regulators, corrosion inhibitors, anti-wear and / or extreme pressure additives, sequestering agents, metal passivating agents, colorants, dispersants, emulsifying agents, and mixtures thereof.
[0135] Advantageously, an aqueous lubricating composition according to the invention may comprise one or more additives chosen from anti-foaming agents, extreme pressure agents, corrosion inhibitors, pH regulators, metal passivating agents, colorants, and mixtures thereof.
[0136] An aqueous lubricating composition according to the invention may more particularly comprise from 0.1 to 10% by mass of additives, in particular from 1.0 to 8.0% by mass of additives, relative to the total mass of the composition.
[0137] pH regulator
[0138] An aqueous lubricating composition according to the invention may comprise at least one pH regulating additive, in particular an alkaline buffer. The pH regulator makes it possible to maintain the desired pH of the lubricating composition, in particular in order to preserve an alkaline pH, advantageously between 8 and 15.
[0139] The said pH regulator(s), by ensuring that the pH of the aqueous lubricating composition is maintained between 8 and 15, makes it possible in particular to prevent corrosion of metal surfaces, but also to promote the solubilization of the various compounds in the lubricating composition, in particular of the polyalkylene glycol(s), in particular as defined above.
[0140] The pH regulator can be chosen from the amine family, in particular alkanolamines and amino alcohols.
[0141] This may include a pH regulating additive selected from alkanolamines, such as dimethylethanolamine (DMEA), ethanolamines, such as monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), isopropanolamines, such as monoisopropanolamine (MIPA), diisopropanolamine (DIPA) and triisopropanolamine (TIPA); diglycolamine (DGA); ethylene amines, such as ethylene diamine (EDA), diethylene triamine (DETA), triethylene tetramine (TETA) and tetraethylene pentamine (TEPA); cyclamines, such as cyclohexylamine; 2-amino-2-ethyl-1,3-propanediol; 2-amino-2-methyl-1-propanol; and mixtures thereof.
[0142] An aqueous lubricating composition according to the invention may in particular comprise from 0.1% to 10% by mass of pH regulating additive(s), preferably from 0.5% to 5% by mass, relative to the total mass of the composition.
[0143] Advantageously, an aqueous lubricating composition used according to the invention comprises at least one pH regulating additive making it possible to maintain the pH of said lubricating composition between 8 and 15, in particular between 8.5 and 14, more particularly between 9 and 13, said pH regulating additive being chosen in particular from alkanolamines, preferably ethanolamines, and more particularly from dimethylethanolamine (DMEA), triethanolamine (TEA) and their mixture.
[0144] Thus, in a particular embodiment, an aqueous lubricating composition required according to the invention comprises at least:
[0145] - water, especially deionized water;
[0146] - at least one polyalkylene glycol, in particular as defined above; and
[0147] - at least one pH regulating additive making it possible to maintain the pH of said lubricating composition between 8 and 15, in particular chosen from alkanolamines, said aqueous lubricating composition comprising a content of phosphate ester salt(s), in particular chosen from alkali metal salts of phosphate esters, strictly less than 0.1% by mass, relative to the total mass of the composition, preferably being free of phosphate ester salts.
[0148] Corrosion inhibitor
[0149] An aqueous lubricating composition according to the invention may comprise at least one corrosion inhibiting agent. Corrosion inhibitors advantageously make it possible to reduce or even prevent the corrosion of metal parts. The nature of said corrosion inhibitor(s) may be chosen with regard to the metal to be protected against corrosion, such as aluminum, steel, galvanized steel, yellow metals, for example copper or brass. Among the inorganic corrosion inhibitors that may be mentioned are nitrites, sulfites, silicates, borates, sodium, potassium, calcium or magnesium phosphates, alkali metal phosphates, hydroxides, molybdates, zinc, magnesium or nickel sulfates.
[0150] Among the organic corrosion inhibitors that may be mentioned are alkanolamines such as triethanolamine, aliphatic monocarboxylic acids, in particular having from 4 to 15 carbon atoms, for example octanoic acid, aliphatic dicarboxylic acids having from 4 to 15 carbon atoms, for example decanedioic acid, undecanedioic acid, dodecanedioic acid or mixtures thereof, polycarboxylic acids optionally neutralized by triethanolamine, such as 1,3,5-triazine-2,4,6-tri-(6-aminocaproic acid), alkanoylamidocarboxylic acids, in particular isononanoylamidocaproic acid, and mixtures thereof. Borated amides, products of the reaction of amines or amino alcohols with boric acid, may also be used.
[0151] Preferably, the corrosion inhibitor(s) are distinct from the pH regulating additive(s), in particular making it possible to maintain the pH of the lubricating composition between 8 and 15, and defined previously.
[0152] An aqueous lubricating composition according to the invention may in particular comprise from 0.1% to 5% by mass of corrosion inhibitor(s), in particular as defined above, preferably from 0.5% to 4% by mass, more preferably from 1% to 2.5% by mass, relative to the total mass of the composition.
[0153] In a particular embodiment, an aqueous lubricating composition required according to the invention comprises at least: - water, in particular deionized water;
[0154] - at least one polyalkylene glycol, in particular as defined above; and
[0155] - at least one corrosion inhibitor, in particular chosen from organic corrosion inhibitors, more particularly from aliphatic monocarboxylic acids, said aqueous lubricating composition comprising a content of phosphate ester salt(s), in particular chosen from alkali metal salts of phosphate esters, strictly less than 0.1% by mass, relative to the total mass of the composition, preferably being free of phosphate ester salts.
[0156] Anti-wear / extreme pressure additive
[0157] An aqueous lubricating composition according to the invention may comprise at least one anti-wear and / or extreme pressure additive. Their function is to reduce wear and the coefficient of friction, or to prevent metal-metal contact by forming a protective film adsorbed on these surfaces.
[0158] There is a wide variety of anti-wear additives, among which can be mentioned those chosen from phosphosulfur additives such as metal alkylthiophosphates or their salts.
[0159] Additives that do not provide phosphorus are preferred, such as, for example, polysulfides, especially sulfur olefins.
[0160] According to a particular embodiment, an aqueous lubricating composition used according to the invention may comprise at least one extreme pressure additive chosen from sulfur-containing fatty acids and dimercaptothiadiazoles, preferably used in their neutralized form, in particular by inorganic alkalizing agents or alkanolamines, emulsifiable or soluble in water.
[0161] Advantageously, an aqueous lubricating composition used according to the invention comprises less than 0.1% by mass of extreme pressure additive of the sulfur-containing fatty acid type, in particular in a neutralized form, preferably less than 0.01% by mass, more particularly less than 0.001% by mass, relative to the total mass of the composition, or even is completely free of extreme pressure additive of the sulfur-containing fatty acid type.
[0162] Sulfur-containing fatty acids can contain from 8 to 22 carbon atoms, in particular
[0163] 12 to 18 carbon atoms. The quantity of sulfur according to ASTM D2622 provided by said sulfur-containing fatty acid(s) may be between 5% and 30% by mass, in particular between 10% and 20% by mass, relative to the total mass of the composition.
[0164] Preferably, the quantity of active sulfur at 150°C according to standard ASTM D 1662 provided by said sulfur-containing fatty acid(s) in the aqueous lubricating composition according to the invention is less than or equal to 2% by mass, in particular less than or equal to 1% by mass, more particularly less than 0.1% by mass, relative to the total mass of the lubricating composition.
[0165] For the purposes of the present invention, the term "active sulfur" means the sulfur that a chemical compound is capable of yielding or releasing when this compound is placed under the conditions of ASTM D1662. ASTM D-1662 defines an active sulfur level of a compound at a given temperature as a difference expressed as a weight percentage of sulfur content before and after reaction of a sample of this sulfur compound with a given quantity of copper for a fixed time.
[0166] As mentioned above, said sulfur-containing fatty acid(s) are generally used in an aqueous lubricating composition in their form neutralized by an alkalizing agent, such as sodium hydroxide, potassium hydroxide, or an alkanolamine, such as monoethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine and triisopropanolamine.
[0167] An aqueous lubricating composition required according to the invention may comprise between 0.01% and 10% by mass of anti-wear and / or extreme pressure additive(s), preferably between 0.2% and 5% by mass, relative to the total mass of the composition.
[0168] Anti-foam
[0169] An aqueous lubricating composition according to the invention may comprise at least one anti-foam additive. Anti-foams make it possible to prevent foaming of the lubricating fluid.
[0170] It may be, for example, an anti-foaming agent based on polysiloxanes or acrylate polymers. Preferably, the anti-foaming agent is chosen from three-dimensional siloxanes.
[0171] Also, the anti-foaming agents may be polar polymers such as polymethylsiloxanes or polyacrylates. In particular, an aqueous lubricating composition according to the invention may comprise from 0.001% to 3.0% by mass of anti-foam additive(s), preferably from 0.005% to 1.5% by mass, more preferably from 0.01% to 1.0% by mass, relative to the total mass of the lubricating composition.
[0172] In a particular embodiment, an aqueous lubricating composition required according to the invention comprises at least:
[0173] - water, especially deionized water;
[0174] - at least one polyalkylene glycol, in particular as defined above; and
[0175] - at least one anti-foam additive, in particular chosen from three-dimensional siloxanes, said aqueous lubricating composition comprising a content of phosphate ester salt(s), in particular chosen from alkali metal salts of phosphate esters, strictly less than 0.1% by mass, relative to the total mass of the composition, preferably being free of phosphate ester salts.
[0176] Metal passivating agents
[0177] An aqueous lubricating composition according to the invention may comprise at least one metal passivating agent. Metal passivating agents make it possible to protect metal parts by promoting the formation of metal oxide on their surface.
[0178] The metal passivating agents may be, for example, selected from triazole derivatives, such as tetrahydrobenzotriazole (THBTZ), tolyltriazole (TTZ), benzotriazole (BTZ), triazole-substituted amines, such as N,N-bis(2-ethylhexyl)-1,2,4-triazol-1-yl methanamine, N'-bis(2 ethylhexyl)-4-methyl-1H-benzotriazol-1-methyl-amine, N,N-bis(heptyl)-ar-methyl-1H-benzotriazole-1-methanamine, N,N-bis(nonyl)-ar-methyl-1H-benzotriazole-1-methanamine, N,N-bis(decyl)-ar-methyl-1H-benzotriazole-1-methanamine, N,N-bis(undecyl)-ar-methyl- 1H- benzotriazole-1 -methanamine, N,N-bis(dodecyl)-ar-methyl-lH-benzotriazole-l-methanamine, N,N-bis(2-ethylhexyl)-ar-methyl-lH-benzotriazole-l-methanamine, 1,2,4-triazoles, benzimidazoles, 2-alkyldithiobenzimidazoles, 2- alkyldithiobenzo thiazoles, 2-(N,N-dialkyldithiocarbamoyl)benzothiazoles, 2,5- bis(alkyldithio)-l,3,4-thiadiazoles, such as 2,5-bis(tert-octyldithio)-l,3,4-thiadiazole, 2.5-bis(tert-nonyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-decyldithio)-1,3,4-thiadiazole,
[0179] 2.5-bis(tert-undecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-dodecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-tridecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-tetradecyldithio)- 1,3,4-thiadiazole, 2,5-bis(tert-pentadecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-hexadecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-heptadecyldithio)-1,3,4-thiadiazole,
[0180] 2,5-bis(tert-octadecyldithio)-l,3,4-thiadiazole, 2,5-bis(tert-nonadecyldithio)-l,3,4-thiadiazole, 2,5-bis(tert-eicosyldithio)-l,3,4-thiadiazole, 2,5-bis(N,N-dialkyldithiocarbamoyl)-l,3,4-thiadiazoles, 2-alkyldithio-5-mercaptothiadiazoles, and mixtures thereof.
[0181] Preferably, the metal passivating agents are chosen from tetrahydrobenzotriazole (THBTZ), tolyltriazole (TTZ), benzotriazole (BTZ), and their salts, taken alone or in mixtures.
[0182] An aqueous lubricating composition according to the invention may in particular comprise from 0.01% to 2.0% by mass of metal passivating agent(s), preferably from 0.1% to 1.0% by mass, more preferably from 0.2% to 0.8% by mass, relative to the total mass of the composition.
[0183] In a particular embodiment, an aqueous lubricating composition required according to the invention comprises at least:
[0184] - water, especially deionized water;
[0185] - at least one polyalkylene glycol, in particular as defined above; and
[0186] - at least one metal passivating agent, in particular chosen from triazole derivatives, more particularly chosen from tetrahydrobenzotriazole (THBTZ), tolyltriazole (TTZ), benzotriazole (BTZ), and their salts, taken alone or in mixtures, said aqueous lubricating composition comprising a content of phosphate ester salt(s), in particular chosen from alkali metal salts of phosphate esters, strictly less than 0.1% by mass, relative to the total mass of the composition, preferably being free of phosphate ester salts.
[0187] Dyes
[0188] An aqueous lubricating composition according to the invention may comprise one or more colorants. The colorants may be natural or synthetic, generally organic. The colorants that may be used in an aqueous lubricating composition may be more particularly chosen from natural or synthetic water-soluble colorants, for example the colorants FDC Red 4, DC Red 6, DC Red 22, DC Red 28, DC Red 30, DC Red 33, DC Orange 4, DC Yellow 5, DC Yellow 6, DC Yellow 8, FDC Green 3, DC Green 5, FDC Blue 1, betanin (beetroot), xanthenes, carmine, a chlorophyllin, methylene blue, anthocyanins (enocyanin, black carrot and hibiscus), caramel and riboflavin.
[0189] An aqueous lubricating composition according to the invention may comprise between 0.01% and 2.0% by mass of colorant(s), preferably between 0.01% and 1.5% by mass, more preferably between 0.02% and 1.0% by mass, relative to the total mass of the composition.
[0190] In a particular embodiment, an aqueous lubricating composition required according to the invention comprises at least:
[0191] - water, especially deionized water;
[0192] - at least one polyalkylene glycol, in particular as defined above; and
[0193] - at least one colorant, in particular chosen from xanthenes, said aqueous lubricating composition comprising a content of phosphate ester salt(s), in particular chosen from alkali metal salts of phosphate esters, strictly less than 0.1% by mass, relative to the total mass of the composition, preferably being free of phosphate ester salts.
[0194] Emulsifying agents
[0195] An aqueous lubricating composition according to the invention may comprise one or more emulsifying agents, also called emulsifiers. Their function is to generate stable emulsions in water.
[0196] The emulsifying agents may be more particularly non-ionic, such as for example ethoxylated fatty alcohols, ethoxylated fatty acids, ethoxylated fatty amides; anionic, for example KOH, NaOH soaps; sulfonates; cationic, such as quaternary ammonium compounds; or even carboxylic acid esters soluble or emulsifiable in water. In particular, an aqueous lubricating composition according to the invention may comprise from 0.01% to 10% by mass of emulsifying agent(s), preferably from 0.1% to 5.0% by mass, relative to the total mass of the lubricating composition.
[0197] Sequestering agents
[0198] An aqueous lubricating composition according to the invention may comprise at least one sequestering agent. Sequestering agents, also called chelating agents, make it possible to limit the encrustation of metal ions in the composition.
[0199] Examples of sequestering agents include those derived from phosphonic acids and phosphonates, such as diethylenetriaminepentamethylphosphonic acid (DTPMPA), aminotri(methylenephosphonic acid) (ATMP), hydroxyethanediphosphonic acid (HEDP), 1,1-hydroxyethylidene diphosphonate, 2-hydroxyethylamine di(methylenephosphonic acid) (HEAMBP), diethylenetriaminopenta(methylenephosphonic acid) (DTMP), multifunctional organic acids and hydroxy acids, such as ethylenediaminetetraacetic acid (EDTA), pteroyl-L-glutamic acid (PGLU), organic polyacids, such as maleic acid and polyaspartic acid, polysaccharides and carbohydrates, such as inulin, carboxymethylinulin and carboxymethylchitosan.
[0200] An aqueous lubricating composition according to the invention may comprise from 0.001% to 2.0% by mass of sequestering agent(s), preferably from 0.01% to 1.0% by mass, relative to the total mass of the composition.
[0201] Biocides and fungicides
[0202] An aqueous lubricating composition according to the invention may comprise at least one biocidal and / or fungicidal agent. The biocides and fungicides may be used to improve the biological stability of the composition by limiting the proliferation of bacteria, fungi and yeasts in the lubricating fluid.
[0203] Such biocides may be selected from parabens, aldehydes, reactive acetylacetone compounds, isothiazolinones, phenolic compounds, acid salts, halogenated compounds, quaternary ammoniums, certain alcohols and mixtures thereof.
[0204] Preferably, the biocides may be chosen from optionally substituted benzisothiazolinones (BIT), such as N-butyl-1,2-benzisothiazolin-3-one, methylisothiazolinones (MIT), mixtures of methylisothiazolinone and chloromethylisothiazolinone (MIT / CMIT), orthophenyl-phenol (OPP) or its sodium salt, 3-iodo-2-propynylbutylcarbamate (IPBC), chloro-cresol and N,N-methylene-bis-morpholine (MBM); sorbic acid; preferably from orthophenyl-phenol (OPP) or its sodium salt, 3-iodo-2-propynylbutylcarbamate, chloro-cresol, benzisothiazolinones and N,N-methylene-isomorpholine.
[0205] An aqueous lubricating composition according to the invention may in particular comprise between 0.01% and 10% by mass of biocide(s) and / or fungicide(s), preferably between 0.5% and 5.0% by mass, relative to the total mass of the composition.
[0206] In a particular embodiment, an aqueous lubricating composition required according to the invention comprises at least:
[0207] - water, especially deionized water;
[0208] - at least one polyalkylene glycol, in particular as defined above; and
[0209] - one or more additives chosen from anti-foaming agents, corrosion inhibitors, pH regulators, metal passivating agents, colorants, in particular as defined above, said aqueous lubricating composition comprising a content of phosphate ester salt(s), in particular chosen from alkali metal salts of phosphate esters, strictly less than 0.1% by mass, relative to the total mass of the composition, preferably being free of phosphate ester salts.
[0210] In a particular embodiment, an aqueous lubricating composition required according to the invention comprises at least:
[0211] - water, especially deionized water;
[0212] - at least one polyalkylene glycol, in particular as defined above;
[0213] - at least one antifreeze compound chosen from glycols, preferably alkylene glycols; glycerol; diglycerol; triglycerol, and mixtures thereof; and
[0214] - one or more additives chosen from anti-foaming agents, corrosion inhibitors, pH regulators, metal passivating agents, colorants, in particular as defined above, said aqueous lubricating composition comprising a content of ZI phosphate ester salt(s), in particular chosen from alkali metal salts of phosphate esters, strictly less than 0.1% by mass, relative to the total mass of the composition, preferably being free of phosphate ester salts.
[0215] According to a particular embodiment, an aqueous lubricating composition used according to the invention comprises:
[0216] - at least 35% by mass of water, in particular 40 to 60% by mass, in particular at least 50% by mass of water, preferably deionized water;
[0217] - from 5.0% to 50% by mass, in particular from 10 to 20% by mass, of at least one polyalkylene glycol, in particular as defined above;
[0218] - optionally from 5.0% to 45%, in particular from 20 to 40% by mass, of at least one antifreeze compound, chosen from glycols, preferably alkylene glycols; glycerol; diglycerol; triglycerol, and mixtures thereof; preferably diethylene glycol; and
[0219] - optionally from 0.1% to 10% by mass of one or more additives chosen from anti-foaming agents, extreme pressure agents, corrosion inhibitors, pH regulators, metal passivating agents, colorants, emulsifying agents, sequestering agents, and mixtures thereof, said aqueous lubricating composition comprising a content of phosphate ester salt(s), in particular chosen from alkali metal salts of phosphate esters, strictly less than 0.1% by mass, preferably being free of phosphate ester salts; the contents being expressed relative to the total mass of the lubricating composition.
[0220] In particular, an aqueous lubricating composition used according to the invention may consist of:
[0221] - from 5.0% to 50% by mass, in particular from 10 to 20% by mass, of at least one polyalkylene glycol, in particular as defined above;
[0222] - optionally from 5.0% to 45%, in particular from 20 to 40% by mass, of at least one antifreeze compound, chosen from glycols, preferably alkylene glycols; glycerol; diglycerol; triglycerol, and mixtures thereof; preferably diethylene glycol; and
[0223] - optionally from 0.1% to 10% by mass of one or more additives chosen from anti-foaming agents, extreme pressure agents, corrosion inhibitors, pH regulators, metal passivating agents, colorants, emulsifying agents, sequestering agents, and mixtures thereof, said aqueous lubricating composition comprising a content of phosphate ester salt(s), in particular chosen from alkali metal salts of phosphate esters, strictly less than 0.1% by mass, in particular being free of phosphate ester salts; the contents being expressed relative to the total mass of the lubricating composition, the remainder consisting of water, preferably deionized water.
[0224] It is understood that the various particular embodiments described above may be combined, to the extent possible, to define other particular embodiments.
[0225] In particular, each of the additives specifically described above may be introduced alone, or in combination with at least one other of the additives specifically described, which defines different variant embodiments of an aqueous lubricating composition according to the invention. In other words, particular embodiments of the invention are defined by an aqueous lubricating composition according to the invention, comprising at least water; and one or more polyalkylene glycol(s), in particular as defined above, preferably in the proportions indicated above, and further comprising one or more of the additives detailed specifically in the text.
[0226] According to a particular embodiment, an aqueous lubricating composition used according to the invention comprises:
[0227] - from 40 to 55% by mass of water, in particular deionized water, in particular more than 45% by mass of water;
[0228] - from 10 to 15% by mass of one or more polyalkylene glycols;
[0229] - optionally from 30 to 40% by mass of an antifreeze compound chosen from glycols, preferably alkylene glycols; glycerol; diglycerol; triglycerol, and mixtures thereof; preferably diethylene glycol;
[0230] - optionally from 0.1% to 10% by mass of one or more additives chosen from anti-foaming agents, corrosion inhibitors, pH regulators, metal passivating agents, colorants, emulsifying agents, sequestering agents, and mixtures thereof, said composition being free from phosphate ester salts and, more preferably, free from phosphorus compounds, said composition being free from extreme pressure additives of the sulfur-containing fatty acid type.
[0231] According to a particular embodiment, an aqueous lubricating composition used according to the invention comprises hypericin in a content strictly less than 0.1% by mass, preferably less than or equal to 0.01% by mass, more preferably less than or equal to 0.01% by mass, relative to the total weight of the composition. In particular, an aqueous lubricating composition used according to the invention is completely free of hypericin.
[0232] More generally, an aqueous lubricating composition used according to the invention comprises one or more polycyclic dianthraquinone compound(s) in a content strictly less than 0.1% by mass, preferably less than or equal to 0.01% by mass, more preferably less than or equal to 0.01% by mass, relative to the total weight of the composition. In particular, an aqueous lubricating composition used according to the invention is completely free of polycyclic dianthraquinone compound.
[0233] APPLICATION
[0234] As indicated above, an aqueous lubricating composition can be implemented, due to its joint properties in terms of lubrication and cooling, both as a cooling fluid and as a lubricating fluid for a propulsion system of an electric or hybrid vehicle, in particular of the engine, the power electronics, the transmission and / or the battery, in an electric or hybrid vehicle, preferably in an electric vehicle.
[0235] As shown schematically in Figure 1, the propulsion system of an electric or hybrid vehicle comprises in particular the electric motor part (1), an electric battery (2) and a transmission, and in particular a speed reducer (3). As batteries suitable for the propulsion systems of an electric or hybrid vehicle, mention may be made in particular of Li-ion batteries or nickel-cadmium batteries. 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 alternately supplied with an electric current. This makes it possible to generate a rotating magnetic field. The rotor itself comprises coils, permanent magnets or other magnetic materials, and is rotated by the rotating magnetic field.
[0236] The power electronics (11), stator (13) and rotor (14) of a propulsion system (1) are parts whose structure is complex and generates a large amount of heat during operation of the motor. It is therefore imperative to ensure cooling of the electric motor and the power electronics.
[0237] A bearing (12) is generally integrated 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 output of the electric motor and to adapt the speed transmitted to the wheels, allowing at the same time to control the speed of the vehicle.
[0238] Advantageously, an aqueous lubricating composition according to the invention can be used to cool the battery present in an electric or hybrid vehicle, in particular in an electric vehicle. In particular, it is intended to be placed in direct contact with the battery.
[0239] Cooling may be implemented by any method known to those skilled in the art. The battery may be immersed or semi-immersed, static or circulating, in said composition.
[0240] Examples of direct contact include cooling by injection, jet, spraying or even by forming a mist from the composition required according to the invention under pressure and by gravity on the battery.
[0241] A composition according to the invention can also be used to cool the electric motor of an electric or hybrid vehicle, in particular to cool the power electronics and / or the rotor and / or the stator of the electric motor, preferably in an electric vehicle.
[0242] An aqueous lubricating composition according to the invention can simultaneously be used to lubricate the various parts of a propulsion system of an electric or hybrid vehicle, in particular the engine, the power electrics, the transmission and / or the battery, more particularly the bearings located between the rotor and the stator of an electric motor, or even the transmission, in particular the reducer, in an electric or hybrid vehicle.
[0243] More particularly, an aqueous lubricating composition according to the invention makes it possible to cool and lubricate an electric motor of an electric or hybrid vehicle. It proves to be particularly effective for cooling the power electronics and / or the rotor and / or the stator of an electric motor. It also ensures the lubrication of the bearings located between the rotor and the stator of an electric motor of an electric or hybrid vehicle.
[0244] Advantageously, an aqueous lubricating composition according to the invention makes it possible to ensure the lubrication of the transmission, when it is present, in particular the reducer, of an electric or hybrid vehicle.
[0245] Thus, advantageously, it is for example possible, by implementing a single composition according to the invention, to ensure both the cooling of the battery and the lubrication of the transmission, in particular the reducer, in an electric or hybrid vehicle.
[0246] Advantageously, the present invention relates to the use of an aqueous lubricating composition as defined according to the invention, for lubricating and / or cooling the reducer and / or the motor and / or the power electronics of an electric vehicle.
[0247] The particular, advantageous or preferred characteristics relating to the uses and methods of implementing an aqueous lubricating composition according to the invention make it possible to define particular, advantageous or preferred modes of an aqueous lubricating composition according to the invention.
[0248] Example
[0249] The invention will now be described by means of the following examples given of course by way of illustration and not limitation of the invention.
[0250] Measurement of pitting by mechanical fatigue
[0251] Pitting by mechanical fatigue (or “pitting” in Anglo-Saxon) is assessed by a test on an MPR tribometer (for “Micro Pitting Rig” in Anglo-Saxon).
[0252] The MPR tribometer is a machine that places a central roller (diameter 12 mm) in contact with three rings (diameter 54 mm) arranged around the roller. This geometric configuration allows the test roller to be subjected to a large number of rolling contact cycles over a short test period, which promotes pitting by mechanical fatigue.
[0253] The test is carried out for a period of 20 hours. The detection of fatigue pitting is done by an accelerometer connected to a vibration monitor. When the vibration setpoint is exceeded due to the occurrence of pitting, the test is stopped.
[0254] The performance of the compositions in terms of pitting by mechanical fatigue is qualified as insufficient if the pitting time is less than 10 hours, average if the pitting time is between 10 hours and 20 hours and good in the absence of pitting after 20 hours of testing.
[0255] EXAMPLE 1
[0256] Preparation of lubricating compositions
[0257] Two aqueous lubricating compositions (II and 12) according to the invention, and a comparative lubricating composition (Cl) comprising a phosphorus compound content greater than 0.1
[0258] % by weight, were formulated by simple mixing, at room temperature, of the following components, in the mass percentages indicated in the following table 1. The percentages are therefore expressed by mass relative to the total mass of the composition
[0259] [Table 1]
[0260] Additive mixture comprising one or more anti-corrosion additives, one or more metal passivating agents, one or more anti-foam additives and / or one or more colorants.
[0261] EXAMPLE 2 Characterization of the compositions according to the invention and comparisons in terms of pitting by mechanical fatigue
[0262] The performances in terms of pitting by mechanical fatigue of composition 12, according to the invention, and of the comparative composition Cl, were evaluated according to the protocol detailed above. The results are presented in Table 2 below:
[0263] [Table 2]
[0264] As is apparent from these results, composition 12, in accordance with the invention, exhibits pitting resistance performances which are much superior to those obtained for comparative composition C1, characterized in particular by the presence of a phosphorus compound in a content greater than 0.1% by weight, relative to the total weight of the composition. Furthermore, compositions II and 12 according to the invention exhibit excellent performances in terms of cooling in an electric or hybrid vehicle propulsion system, in particular cooling of the electric motor. Consequently, an aqueous lubricating composition according to the invention can be used for the lubrication and / or cooling of an electric or hybrid vehicle propulsion system, without exhibiting any adverse effect on pitting by mechanical fatigue of the parts lubricated and / or cooled using said composition.
Claims
Demands 1. Use, for cooling and / or lubricating a propulsion system of an electric or hybrid vehicle, of an aqueous lubricant composition comprising at least: - water; and - at least one polyalkylene glycol; said aqueous lubricating composition comprising a content of phosphate ester salt(s), in particular selected from alkali metal salts of phosphate esters, strictly less than 0.1% by mass, relative to the total mass of said composition.
2. Use according to claim 1, wherein the aqueous lubricating composition further comprises at least one antifreeze compound selected from glycols, preferably alkylene glycols, glycerol, diglycerol, triglycerol, and mixtures thereof, more preferably from monoethylene glycol, diethylene glycol, propylene glycol, glycerol and mixtures thereof.
3. Use according to the preceding claim, wherein the aqueous lubricating composition comprises at least 1.0% by mass of antifreeze compound(s), preferably between 5.0% and 50% by mass, more preferably between 10% and 45% by mass, in particular between 20% and 40% by mass, relative to the total mass of said composition.
4. Use according to any one of the preceding claims, wherein the water is reverse osmosis water, in particular deionized water.
5. Use according to any one of the preceding claims, wherein the aqueous lubricating composition comprises at least 20% by mass of water, in particular deionized water, preferably between 35% and 90% by mass, more preferably between 40% and 75% by mass, in particular between 40% and 60% by mass, relative to the total mass of said composition.
6. Use according to any one of the preceding claims, characterized in that said polyalkylene glycol(s) comprises at least 50% by mass, in particular at least 80% by mass, more preferably at least 90% by mass of propylene oxide and / or ethylene oxide units, in particular said polyalkylene glycol(s) is an ethylene oxide / propylene oxide copolymer.
7. Use according to any one of the preceding claims, characterized in that said polyalkylene glycol(s) has a kinematic viscosity measured at 100 °C (KV100), according to ASTM D445, ranging from 100 to 25,000 mm 2 / s, particularly between 150 and 10,000 mm 2 / s.
8. Use according to any one of the preceding claims, wherein the aqueous lubricating composition comprises at least 5.0% by mass of polyalkylene glycol(s), preferably between 5.0% and 50% by mass, more preferably between 10% and 40% by mass, in particular between 10% and 20% by mass, relative to the total mass of the composition.
9. Use according to any one of the preceding claims, wherein the aqueous lubricating composition comprises less than 0.05% by mass of phosphate ester salt(s), in particular selected from alkali metal salts of phosphate esters, preferably less than 0.01% by mass, more particularly less than 0.001% by mass, relative to the total mass of the composition, the aqueous lubricating composition being more preferably totally free of phosphate ester salts, in particular alkali metal salts of phosphate esters.
10. Use according to any one of the preceding claims, wherein the aqueous lubricating composition further comprises at least one additive selected from antifoaming agents, biocides, pH regulators, corrosion inhibitors, anti-wear and / or extreme-pressure additives, sequestering agents, metal passivating agents, colorants, dispersants, emulsifying agents, and mixtures thereof, preferably selected from antifoaming agents, extreme-pressure agents, corrosion inhibitors, pH regulators, metal passivating agents, colorants, and mixtures thereof.
11. Use according to any one of the preceding claims, wherein the aqueous lubricating composition further comprises at least one pH regulating additive for maintaining the pH of the lubricating composition between 8 and 15, in particular selected from alkanolamines.
12. Use according to any one of the preceding claims, wherein the aqueous lubricating composition comprises less than 0.1% by mass of an extreme-pressure additive of the sulfur fatty acid type, preferably less than 0.01% by mass, more particularly less than 0.001% by mass, relative to the total mass of the composition, more preferably is totally free of extreme-pressure additive of the sulfur fatty acid type.
13. Use of an aqueous lubricating composition as defined according to any one of the preceding claims, for lubricating and / or cooling the gearbox and / or the motor and / or the power electronics of an electric vehicle.
14. Use of an aqueous lubricating composition intended to lubricate and / or cool a propulsion system of an electric or hybrid vehicle, comprising at least: - water; and - at least one polyalkylene glycol; said aqueous lubricating composition comprising a content of phosphate ester salt(s), in particular selected from alkali metal salts of phosphate esters, strictly less than 0.1% by mass, relative to the total mass of said composition, to reduce pitting by mechanical fatigue of the mechanical part(s) of said propulsion system, brought into contact with said composition.
15. Aqueous lubricating composition for the lubrication and / or cooling of an electric or hybrid propulsion system, comprising at least: - at least 45% water by mass, relative to the total mass of the composition; and - at least one polyalkylene glycol; said aqueous lubricating composition comprising a content of phosphate ester salt(s), in particular selected from alkali metal salts of phosphate esters, strictly less than 0.1% by mass, relative to the total mass of said composition.
16. Aqueous lubricating composition according to the preceding claim, said composition being as defined according to any one of claims 2 to 4 or 6 to 12.