Aqueous composition for lubricating and/or cooling a propulsion system of an electric or hybrid vehicle

Abstract

The present application concerns the use, for cooling and/or lubricating a propulsion system of an electric or hybrid vehicle, of an aqueous lubricating composition comprising at least: water and a polyalkylene glycol; the said aqueous lubricating composition comprising a phosphate ester salt(s) content of strictly less than 0.1% by mass, relative to the total mass of the said composition.It also relates to the use of such an aqueous lubricant composition to reduce pitting by mechanical fatigue of the mechanical part(s) of an electric or hybrid vehicle propulsion system which is (are) brought into contact with the said composition.Lastly, it relates to an aqueous lubricating composition for lubricating and/or cooling an electric or hybrid propulsion system, comprising: at least 45% by mass of water, relative to the total mass of the composition, and a polyalkylene glycol; the said composition comprising a phosphate ester salt(s) content of strictly less than 0.1% by mass, relative to the total mass of the said composition.

1 . The 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   one polyalkylene glycol;   
       said aqueous lubricant composition comprising a content of salt(s) of phosphate ester(s), in particular chosen from alkali metal salts of phosphate esters, strictly less than 0.1% by weight, relative to the total weight of said composition. 
     
     
         2 . The use as claimed in  claim 1 , wherein the aqueous lubricant composition further comprises at least one antifreeze compound chosen from glycols, preferably alkylene glycols, glycerol, diglycerol, triglycerol, and mixtures thereof, more preferentially from monoethylene glycol, diethylene glycol, propylene glycol, glycerol and mixtures thereof. 
     
     
         3 . The use as claimed in  the preceding claim , wherein the aqueous lubricant composition comprises at least 1.0% by weight of antifreeze compound(s), preferably between 5.0% and 50% by weight, more preferentially between 10% and 45% by weight, in particular between 20% and 40% by weight, relative to the total weight of said composition. 
     
     
         4 . The use as claimed in  any one of the preceding claims , wherein the water is osmosed water, in particular deionized water. 
     
     
         5 . The use as claimed in  any one of the preceding claims , wherein the aqueous lubricant composition comprises at least 20% by weight of water, in particular of deionized water, preferably between 35% and 90% by weight, more preferentially between 40% and 75% by weight, in particular between 40% and 60% by weight, relative to the total weight of said composition. 
     
     
         6 . The use as claimed in  any one of the preceding claims , characterized in that said polyalkylene glycol(s) comprise at least 50% by weight, in particular at least 80% by weight, more preferentially at least 90% by weight of propylene oxide and/or ethylene oxide units, said polyalkylene glycol(s) in particular being an ethylene oxide/propylene oxide copolymer. 
     
     
         7 . The use as claimed in  any one of the preceding claims , characterized in that said polyalkylene glycol(s) has (have) a kinematic viscosity measured at 100° C. (KV100), according to the standard ASTM D445, of between 100 and 25 000 mm 2 /s, in particular between 150 and 10 000 mm 2 /s. 
     
     
         8 . The use as claimed in  any one of the preceding claims , wherein the aqueous lubricant composition comprises at least 5.0% by weight of polyalkylene glycol(s), preferably between 5.0% and 50% by weight, more preferentially between 10% and 40% by weight, in particular between 10% and 20% by weight, relative to the total weight of the composition. 
     
     
         9 . The use as claimed in  any one of the preceding claims , wherein the aqueous lubricant composition comprises less than 0.05% by weight of phosphate ester salt(s), in particular chosen from alkali metal salts of phosphate esters, preferably less than 0.01% by weight, more particularly less than 0.001% by weight, relative to the total weight of the composition, the aqueous lubricant composition being more preferentially completely free of phosphate ester salts, in particular of alkali metal salts of phosphate esters. 
     
     
         10 . The use as claimed in  any one of the preceding claims , wherein the aqueous lubricant composition further comprises at least one additive chosen from antifoaming agents, biocides, pH regulators, corrosion inhibitors, antiwear and/or extreme-pressure additives, sequestrants, metal passivating agents, dyes, dispersants, emulsifying agents and mixtures thereof, preferably chosen from antifoaming agents, extreme-pressure agents, corrosion inhibitors, pH regulators, metal passivating agents, dyes, and mixtures thereof. 
     
     
         11 . The use as claimed in  any one of the preceding claims , wherein the aqueous lubricant composition further comprises at least one pH-regulating additive making it possible to maintain the pH of the lubricant composition between 8 and 15, in particular chosen from alkanolamines. 
     
     
         12 . The use as claimed in  any one of the preceding claims , wherein the aqueous lubricant composition comprises less than 0.1% by weight of extreme-pressure additive of sulfur-containing fatty acid type, preferably less than 0.01% by weight, more particularly less than 0.001% by weight, relative to the total weight of the composition, more preferentially is completely free of extreme-pressure additive of sulfur-containing fatty acid type. 
     
     
         13 . The use of an aqueous lubricant composition as defined in  any one of the preceding claims , for lubricating and/or cooling the reduction gear and/or the motor and/or the power electronics of an electric vehicle. 
     
     
         14 . The use of an aqueous lubricant composition intended to lubricate and/or cool a propulsion system of an electric or hybrid vehicle, comprising at least:
 water; and   one polyalkylene glycol;   
       said aqueous lubricant composition comprising a content of salt(s) of phosphate ester(s), in particular chosen from alkali metal salts of phosphate esters, strictly less than 0.1% by weight, relative to the total weight of said composition, 
       for reducing mechanical fatigue pitting, of the mechanical part(s) of said propulsion system in contact with said composition. 
     
     
         15 . An aqueous lubricant composition for lubricating and/or cooling an electric or hybrid propulsion system, comprising at least:
 45% by weight of water, relative to the total weight of the composition; and   one polyalkylene glycol;   
       said aqueous lubricant composition comprising a content of salt(s) of phosphate ester(s), in particular chosen from alkali metal salts of phosphate esters, strictly less than 0.1% by weight, relative to the total weight of said composition. 
     
     
         16 . The aqueous lubricant composition as claimed in  the preceding claim , said composition being as defined in any one of  claims 2 to 4 or 6 to 12 .