Composition for cooling and lubricating a drive system of a vehicle

Abstract

A composition with a kinematic viscosity for cooling and lubricating a drive system of an electric or hybrid vehicle, measured at 100° C. in accordance with the standard ASTM D445, in the range 3 to 10 mm 2 /s. The composition includes 70% to 90% of a base oil or a mixture of base oils having a kinematic viscosity, measured at 100° C. in accordance with the standard ASTM D445, of 1.5 to 8 mm 2 /s and selected from polyalphaolefins; and at least one thickening polymer.

1 . A method for cooling and lubricating a drive system of an electric or hybrid vehicle, comprising at least a step of bringing at least one mechanical part of said system into contact with a composition having a kinematic viscosity, measured at 100° C. in accordance with the standard ASTM D445, in the range 3 to 10 mm 2 /s (cSt), and comprising at least:
 70% to 90% by weight of base oil, or a mixture of base oils, having a kinematic viscosity, measured at 100° C. in accordance with the standard ASTM D445, of 1.5 to 8 mm 2 /s and selected from polyalphaolefins; and 
 at least one thickening polymer selected from ester polymers; linear or star, hydrogenated or non-hydrogenated homopolymers or copolymers of styrene, butadiene and isoprene; polyacrylates; linear or comb polymethacrylates; and olefin copolymers. 
 
     
     
         2 . The method as claimed in  claim 1 , wherein composition having a kinematic viscosity, measured at 100° C. in accordance with the standard ASTM D445, is in the range 3 to 9 mm 2 /s. 
     
     
         3 . The method as claimed in  claim 1 , wherein the thickening polymer or polymers are selected from comb polymethacrylates, hydrogenated star copolymers of styrene, butadiene and isoprene, and their mixtures. 
     
     
         4 . The method as claimed in  claim 1 , wherein the composition comprises 0.5% to 10% by weight of thickening polymer(s) with respect to the total weight of the composition. 
     
     
         5 . The method as claimed in  claim 1 , said composition further comprises at least one additive selected from friction modifiers, detergents, anti-wear additives, extreme pressure additives, dispersants, antioxidants, pour point improvers, anti-foaming agents and their mixtures. 
     
     
         6 . The method as claimed in  claim 1 , for cooling and lubricating an electric motor of an electric or hybrid vehicle. 
     
     
         7 . The method as claimed in  claim 6 , for cooling the power electronics and/or the rotor and/or the stator of an electric motor. 
     
     
         8 . The method as claimed in  claim 6 , for lubricating the bearings located between the rotor and the stator of an electric motor. 
     
     
         9 . The method as claimed in  claim 1 , for cooling the battery of an electric or hybrid vehicle. 
     
     
         10 . The method as claimed in  claim 1 , for lubricating the transmission of an electric or hybrid vehicle. 
     
     
         11 . The method as claimed in  claim 1 , said composition comprising 1.5% to 5% by weight of thickening polymer(s) with respect to the total weight of the composition. 
     
     
         12 . The method as claimed in  claim 10 , for lubricating the reduction gear of an electric or hybrid vehicle.