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US-20260125612-A1 - LUBRICATING FLUID FOR AN ELECTRIC MOTOR

US20260125612A1US 20260125612 A1US20260125612 A1US 20260125612A1US-20260125612-A1

Abstract

An electric motor lubricating fluid for an electric motor system including a lubricating base oil, a tolyltriazole corrosion inhibitor, an oil-soluble phosphorus antiwear additive, and a sulfonate detergent in amounts to facilitate effective performance in copper leaching and extreme pressure scuffing when in the presence of the tolyltriazole.

Inventors

  • Jessica RODRIGUEZ
  • Mark Devlin
  • Kearsley Dillion
  • Keith Sutyak
  • Andre Williams

Assignees

  • AFTON CHEMICAL CORPORATION

Dates

Publication Date
20260507
Application Date
20241101

Claims (20)

  1. 1 . An electric motor lubricating fluid suitable for electric or hybrid-electric vehicles, the electric motor lubricating fluid comprising: one or more base oils of lubricating viscosity; about 1 to about 35 ppm of nitrogen provided by a tolyltriazole corrosion inhibitor; an oil-soluble phosphorus antiwear additive including an ashless dialkyl dithiophosphoric acid providing about 40 ppm to about 150 ppm of phosphorus and about 85 ppm to about 315 ppm sulfur to the electric motor lubricating fluid; a succinimide dispersant derived from a hydrocarbyl-substituted dicarboxylic acid or anhydride reacted with polyalkylene polyamines having one or more primary or secondary amines, wherein the one or more primary or secondary amines are post-treated with a capping agent; a sulfonate detergent in amounts to contribute a TBN of about 0.04 to about 1.5 mg KOH/g (ASTM D2896) to the electric motor lubricating fluid; and wherein the electric motor lubricating fluid contains less than about 500 ppm sulfur and about 70 to about 150 ppm phosphorus; and wherein a ratio of the amount phosphorus (ppm) delivered from the ashless dialkyl dithiophosphoric acid to the fluid and the amount of nitrogen (ppm) delivered from the tolyltriazole corrosion inhibitor to the fluid (EP Phos+CI Nitrogen) relative to a TBN factor is about 20,000 to about 70,000 and wherein the TBN factor is the TBN (ASTM D2896) delivered by the detergent to the fluid divided by the amount of metal (ppm) delivered from the detergent to the fluid (TBN/Det metal).
  2. 2 . The electric motor lubricating fluid of claim 1 , wherein the tolyltriazole corrosion inhibitor includes methyl-1H-benzotriazole.
  3. 3 . (canceled)
  4. 4 . The electric motor lubricating fluid of claim 1 , wherein the sulfonate detergent is calcium sulfonate and provides about 30 to about 600 ppm calcium to the electric motor lubricating fluid.
  5. 5 . The electric motor lubricating fluid of claim 1 , wherein the oil-soluble phosphorus antiwear additive including the ashless dialkyl dithiophosphate is made by a process comprising the steps of (a) reacting an organic hydroxy compound with phosphorus pentasulfide to form a reaction product and (b) further reacting the reaction product with an unsaturated carboxylic acid to form the oil-soluble phosphorus antiwear additive including the ashless dialkyl dithiophosphate.
  6. 6 . The electric motor lubricating fluid of claim 1 , wherein the ashless dialkyl dithiophosphate includes a compound of Formula I, or a salt thereof: wherein R 4 and R 5 are, independently, a C 1 to C 10 linear or branched alkyl group, and R 6 is —H or —CH 3 .
  7. 7 . The electric motor lubricating fluid of claim 6 , wherein the ashless dialkyl dithiophosphate includes 3-[[bis(2-methylpropoxy) phosphinothioyl]thio]-2-methyl-propanoic acid.
  8. 8 . The electric motor lubricating fluid of claim 1 , wherein the succinimide dispersant is post treated with a phosphorus containing compound and/or a boron containing compound.
  9. 9 . The electric motor lubricating fluid of claim 8 , wherein the succinimide dispersant delivers about 20 to about 100 ppm phosphorus and about 5 to about 50 ppm boron to the electric motor lubricating fluid.
  10. 10 . The electric motor lubricating fluid of claim 1 , wherein the sulfonate detergent is provided in amounts to contribute a TBN of about 0.2 to about 0.6.
  11. 11 . The electric motor lubricating fluid of claim 1 , wherein the electric motor lubricating fluid exhibits about 30 ppm or less of copper leaching pursuant to ASTM D130.
  12. 12 . The electric motor lubricating fluid of claim 11 , wherein the electric motor lubricating fluid has a failure load stage rating of 8 or higher in the FZG A10/16.6R/120 test of ASTM D5182.
  13. 13 . The electric motor lubricating fluid of claim 1 , wherein the electric motor lubricating fluid contains less than about 300 ppm of sulfur.
  14. 14 . A method for lubricating a driveline component including an electric motor, the method comprising: lubricating the driveline component with an electric motor lubricating fluid and wherein the electric motor lubricating fluid contacts portions of the electric motor; wherein in the electric motor lubricating fluid includes (i) one or more base oils of lubricating viscosity, (ii) about 1 to about 35 ppm of nitrogen provided by a tolyltriazole corrosion inhibitor; (iii) an oil-soluble phosphorus antiwear additive including an ashless dialkyl dithiophosphoric acid providing about 40 ppm to about 150 ppm of phosphorus and about 85 ppm to about 315 ppm sulfur to the electric motor lubricating fluid, (iv) a succinimide dispersant derived from a hydrocarbyl-substituted dicarboxylic acid or anhydride reacted with polyalkylene polyamines having one or more primary or secondary amines, wherein the one or more primary or secondary amines are post-treated with a capping agent; (v) a sulfonate detergent provided in amounts to contribute a TBN of about 0.04 to about 1.5 mg KOH/g to the electric motor lubricating fluid; and (vi) wherein the electric motor lubricating fluid contains less than about 500 ppm sulfur and about 70 to about 150 ppm phosphorus; and wherein the electric motor lubricating fluid exhibits about 30 ppm or less of copper leaching pursuant to ASTM D130 and has a failure load stage rating of 8 or higher in the FZG A10/16.6R/120 test of ASTM D5182; and wherein a ratio of the amount phosphorus (ppm) delivered from the ashless dialkyl dithiophosphoric acid to the fluid and the amount of nitrogen (ppm) delivered from the tolyltriazole corrosion inhibitor to the fluid (EP Phos+CI Nitrogen) relative to a TBN factor is about 20,000 to about 70,000 and wherein the TBN factor is the TBN (ASTM D2896) delivered by the detergent to the fluid divided by the amount of metal (ppm) delivered from the detergent to the fluid (TBN/Det metal).
  15. 15 . The method of claim 14 , wherein the triazole corrosion inhibitor includes methyl benzotriazole.
  16. 16 . (canceled)
  17. 17 . The method of claim 14 , wherein the sulfonate detergent is calcium sulfonate and provides about 30 to about 600 ppm calcium to the electric motor lubricating fluid.
  18. 18 . The method of claim 14 , wherein the oil-soluble phosphorus antiwear additive including the ashless dialkyl dithiophosphate is made by a process comprising the steps of (a) reacting an organic hydroxy compound with phosphorus pentasulfide to form a reaction product and (b) further reacting the reaction product with an unsaturated carboxylic acid to form the oil-soluble phosphorus antiwear additive including the ashless dialkyl dithiophosphate.
  19. 19 . The method of claim 14 , wherein the ashless dialkyl dithiophosphate includes a compound of Formula I, or a salt thereof: wherein R 4 and R 5 are, independently, a C 1 to C 10 linear or branched alkyl group, and R 6 is —H or —CH 3 .
  20. 20 . The method of claim 19 , wherein the ashless dialkyl dithiophosphate includes 3-[[bis(2-methylpropoxy) phosphinothioyl]thio]-2-methyl-propanoic acid.

Description

TECHNICAL FIELD The present disclosure relates to methods of using a lubricating fluid and a lubricating fluid for an electric motor system. In particular, the disclosed methods and compositions relate to a lubricating fluid suitable for electric or hybrid-electric vehicles including a tolyltriazole corrosion inhibitor, an ashless dialkyl dithiophosphoric acid, and detergent that achieves copper corrosion and extreme pressure performance. BACKGROUND A major challenge in developing electric vehicle powertrain lubricants is achieving acceptable extreme pressure performance while minimizing copper leaching for compatibility with electrical components in the electric vehicle powertrain. Tolyltriazole compounds (e.g., methyl-benzotriazole) are effective metal deactivators that inhibit copper from leaching into the lubricant but have been discovered to negatively impact the performance of certain extreme pressure additives. For instance, combining tolyltriazole with an ashless dialkyl dithiophosphoric acid extreme pressure additive in electric vehicle powertrain lubricants leads to lower failure load stage (FLS) in FZG performance (e.g., A10/16.6R/120 scuffing test of CEC L-84-02). If the tolyltriazole is eliminated from the composition, the FZG FLS improves, but copper leaching also increases. SUMMARY In one embodiment, an electric motor lubricating fluid suitable for electric or hybrid-electric vehicles is described herein. In one aspect of this embodiment, the electric motor lubricating fluid includes one or more base oils of lubricating viscosity; at least about 1 ppm of nitrogen provided by a tolyltriazole corrosion inhibitor; an oil-soluble phosphorus antiwear additive including an ashless dialkyl dithiophosphoric acid providing about 40 ppm to about 150 ppm of phosphorus and about 85 ppm to about 315 ppm sulfur to the electric motor lubricating fluid; a succinimide dispersant derived from a hydrocarbyl-substituted dicarboxylic acid or anhydride reacted with polyalkylene polyamines having one or more primary or secondary amines, wherein the one or more primary or secondary amines are post-treated with a capping agent; a sulfonate detergent in amounts to contribute a TBN of about 0.02 to about 1.9 (ASTM D2896) to the electric motor lubricating fluid; and wherein the electric motor lubricating fluid contains less than about 500 ppm sulfur and at least about 70 ppm phosphorus. In other approaches or embodiments, the electric motor lubricating fluid of the previous paragraph may include other features or embodiments in any combination. These other features or embodiments may include one or more of the following: wherein the tolyltriazole corrosion inhibitor includes methyl-1H-benzotriazole; and/or wherein a ratio of the amount phosphorus (ppm) delivered from the ashless dialkyl dithiophosphoric acid to the fluid and the amount of nitrogen (ppm) delivered from the tolyltriazole corrosion inhibitor to the fluid (EP Phos+CI Nitrogen) relative to a TBN factor is about 70,000 or less and wherein the TBN factor is the TBN (ASTM D2896) delivered by the detergent to the fluid divided by the amount of metal (ppm) delivered from the detergent to the fluid (TBN/Det metal); and/or wherein the sulfonate detergent is calcium sulfonate and provides about 30 to about 600 ppm calcium to the electric motor lubricating fluid; and/or wherein the oil-soluble phosphorus antiwear additive including the ashless dialkyl dithiophosphate is made by a process comprising the steps of (a) reacting an organic hydroxy compound with phosphorus pentasulfide to form a reaction product and (b) further reacting the reaction product with an unsaturated carboxylic acid to form the oil-soluble phosphorus antiwear additive including the ashless dialkyl dithiophosphate; and/or wherein the ashless dialkyl dithiophosphate includes a compound of Formula I, or a salt thereof: wherein R4 and R5 are, independently, a C1 to C10 linear or branched alkyl group, and R6 is —H or —CH3; and/or wherein the ashless dialkyl dithiophosphate includes 3-[[bis(2-methylpropoxy) phosphinothioyl]thio]-2-methyl-propanoic acid; and/or wherein the succinimide dispersant is post treated with a phosphorus containing compound and/or a boron containing compound; and/or wherein the succinimide dispersant delivers about 20 to about 100 ppm phosphorus and about 5 to about 50 ppm boron to the electric motor lubricating fluid; and/or wherein the sulfonate detergent is provided in amounts to contribute a TBN of about 0.2 to about 0.6; and/or wherein the electric motor lubricating fluid exhibits about 30 ppm or less of copper leaching pursuant to ASTM D130; and/or wherein the electric motor lubricating fluid has a failure load stage rating of 8 or higher in the FZG A10/16.6R/120 test of ASTM D5182; and/or wherein the electric motor lubricating fluid contains less than about 300 ppm of sulfur. In yet other approaches or embodiments, a method for lubricating a driveline component including