Polyol Ester Based Drive-Train Fluid for High Stress Automatic Transmissions

Abstract

The use of certain polyol ester (POE) based fluids has been found to be surprisingly effective in, e.g., automotive automatic transmissions, such as, for example, racing automotive automatic transmissions. The use of select POE based fluids has been found to lower operating temperatures, improve torque convertor engagement and torque convertor lock-up due to improved efficiency, performance and friction properties, allowing improved efficiency in high stress applications.

1 . A mechanical device comprising a fluid coupling and a hydraulic transfer fluid, said hydraulic transfer fluid being a working fluid comprising:
 i) from 80 to 99% by weight of a polyol ester composition comprising C 5-10  alkylcarboxlate esters of pentaerythritol, di-pentaerythritol, tri-pentaerythritol and/or higher pentaerythritol oligomers; and   ii) from 1 to 20% by weight of additives selected from dispersants; anti-wear agents;   anti-oxidants; corrosion inhibitors; friction modifiers; seal swell agents; anti-foamants viscosity modifiers, detergents, pour point depressants;   wherein the working fluid has a kinematic viscosity at 40° C. of from 4 to 64 cSt, a kinematic viscosity at 100° C. of from 2 to 28 cSt, and a viscosity index of greater than greater than 100.   
     
     
         2 . The mechanical device according to  claim 1  wherein 70 to 100% by weight of the esters of the polyol ester composition (i) are compounds of formula Ia and IIa 
       
         
           
           
               
               
           
         
       
       wherein each R is independently selected from the group consisting of pentanoyl, hexanoyl, heptanoly, octanoyl, nonanoyl, decanoyl and branched isomers thereof. 
     
     
         3 . The mechanical device according to  claim 2  wherein 80 to 100 mol % of the R groups in formula (Ia) and (IIa) are linear alkanoyl. 
     
     
         4 . The mechanical device according to  claim 1  wherein the working fluid has a kinematic viscosity at 40 ° C. of from 10 to 40 cSt, a kinematic viscosity at 100 ° C. of from 2 to 10 cSt and a pour point of −25° C. or lower 
     
     
         5 . The mechanical device according to  claim 3  wherein 90 to 100% of the esters of the polyol ester composition (i) are compounds of formula Ia and IIa in a weight ratio of compounds of formula Ia to IIa of from 2:1 to 15:1. 
     
     
         6 . The mechanical device according to  claim 5  wherein the weight ratio of compounds of formula Ia to IIa in the polyol ester composition (i) is from 6:1 to 15:1. 
     
     
         7 . The mechanical device according to  claim 6  wherein the polyol ester composition (i) of the working fluid comprises compounds of formula Ia and IIa wherein:
 a) from 5 to 45 mol % of all R groups are C 5  alkanoyl; 
 b) from 5 to 45 mol %, of all R groups are C 8  alkanoyl; 
 c) from 5 to 45 mol %, of all R groups are C 7  alkanoyl; 
 d) from 5 to 45 mol %, of all R groups are C 8  alkanoyl; 
 e) from 5 to 45 mol %, of all R groups are C 9  alkanoyl; and/or 
 f) from 5 to 45 mol %, of all R groups are C 10  alkanoyl; 
 
       provided that at least 3 of a), b), c), d), e) and f) are present in at least 5 mol %. 
     
     
         8 . The mechanical device according to  claim 7  wherein the polyol ester composition (i) of the working fluid comprises compounds of formula Ia and IIa wherein:
 from 25 to 40 mol % of all R groups are C 5  alkanoyl; 
 from 15 to 30 mol %, of all R groups are C 7  alkanoyl; 
 from 15 to 30 mol %, of all R groups are C 9  alkanoyl; and 
 from 0 to 30 mol % of all R groups are selected from C 8 , C 8  and C 10  alkanoyl 
 
     
     
         9 . The mechanical device according to  claim 8  wherein the polyol ester composition (i) of the working fluid comprises compounds of formula Ia and IIa wherein:
 from 30 to 40 mol % of all R groups are pentanoyl, 
 from 15 to 25 mol % of all R groups are C 7  heptanoyl, 
 from 15 to 25 mol %, of all R groups are C 9  nonanoyl, and the remainder of R groups are selected from hexanoyl and octanoyl. 
 
     
     
         10 . The mechanical device according to  claim 1  wherein the fluid coupling is torque converter. 
     
     
         11 . The mechanical device according to  claim 10  which is an automatic transmission. 
     
     
         12 . The automatic transmission according to  claim 11  which is an automatic transmission in a racing vehicle, pickup truck, off road vehicle, delivery truck, ATV, or monster truck. 
     
     
         13 . The automatic transmission according to  claim 12  which is an automatic transmission in a car used in drag racing or monster truck. 
     
     
         14 . An improved method for operating an automatic transmission comprising a fluid coupling and a hydraulic transfer fluid, the improvement being selecting as the hydraulic transfer fluid a working fluid comprising:
 i) from 80 to 99% by weight of a polyol ester composition comprising C 5-10  alkylcarboxlate esters of pentaerythritol, di-pentaerythritol, tri-pentaerythritol and/or higher pentaerythritol oligomers; and   ii) from 1 to 20% by weight of additives selected from dispersants; anti-wear agents;   anti-oxidants; corrosion inhibitors; friction modifiers; seal swell agents; anti-foamants viscosity modifiers, detergents, pour point depressants;   wherein the working fluid has a kinematic viscosity at 40° C. of from 4 to 64 cSt, a kinematic viscosity at 100° C. of from 2 to 28 cSt, and a viscosity index of greater than greater than 100.   
     
     
         15 . The improved method according to  claim 14  wherein 80 to 100% by weight of the esters of the polyol ester composition (i) are compounds of formula Ia and IIa 
       
         
           
           
               
               
           
         
       
       wherein each R is independently selected from the group consisting of pentanoyl, hexanoyl, heptanoly, octanoyl, nonanoyl, decanoyl and branched isomers thereof. 
     
     
         16 . The improved method according to  claim 15  wherein 80 to 100 mol % of the R groups in formula (Ia) and (IIa) are linear alkanoyl. 
     
     
         17 . The improved method according to  claim 16  wherein 90 to 100% of the esters of the polyol ester composition (i) are compounds of formula Ia and IIa in a weight ratio of compounds of formula Ia to IIa of from 6:1 to 15:1. 
     
     
         18 . The improved method according to  claim 17  wherein the polyol ester composition (i) of the working fluid comprises compounds of formula Ia and IIa wherein:
 a) from 5 to 45 mol% of all R groups are C 5  alkanoyl; 
 b) from 5 to 45 mol %, of all R groups are C 6  alkanoyl; 
 c) from 5 to 45 mol %, of all R groups are C 7  alkanoyl; 
 d) from 5 to 45 mol %, of all R groups are C 8  alkanoyl; 
 e) from 5 to 45 mol %, of all R groups are C 9  alkanoyl; and/or 
 f) from 5 to 45 mol %, of all R groups are C 10  alkanoyl; 
 provided that at least 3 of a), b), c), d), e) and f) are present in at least 5 mol %. 
 
     
     
         19 . The improved method according to  claim 18  wherein the polyol ester composition (i) of the working fluid comprises compounds of formula Ia and IIa wherein:
 from 25 to 40 mol % of all R groups are C 5  alkanoyl; 
 from 15 to 30 mol %, of all R groups are C 7  alkanoyl; 
 from 15 to 30 mol %, of all R groups are C 9  alkanoyl; and 
 from 0 to 30 mol % of all R groups are selected from C 6 , C 8  and C 10  alkanoyl 
 
     
     
         20 . The improved method according to  claim 19  wherein the polyol ester composition (i) of the working fluid comprises compounds of formula Ia and IIa wherein:
 from 30 to 40 mol % of all R groups are pentanoyl, 
 from 15 to 25 mol % of all R groups are C 7  heptanoyl, 
 from 15 to 25 mol %, of all R groups are C 9  nonanoyl, and 
 the remainder of R groups are selected from hexanoyl and octanoyl.