Six-speed powertrain of an automatic transmission

Abstract

Durability and power transmission efficiency are enhanced in a six-speed powertrain of an automatic transmission by a scheme that includes first to forth planetary gearsets. The first planetary gearset includes a first sun gear, first ring gear, and first carrier. The second planetary gearset includes a second sun gear, a second ring gear, and a second carrier. The third planetary gearset includes operational elements of a third sun gear, a third ring gear, and a third carrier. The fourth planetary gearset includes a fourth sun gear, a fourth ring gear, and a fourth carrier. The powertrain also includes an input shaft, an output gear, and a transmission case.

1 . A six-speed powertrain of an automatic transmission, comprising: 
 a first planetary gear set having operational elements of a first sun gear, a first ring gear, and a first carrier;    a second planetary gear set having operational elements of a second sun gear, a second ring gear, and a second carrier;    a third planetary gear set having operational elements of a third sun gear, a third ring gear, and a third carrier;    an input shaft;    at least one output gear; and    a transmission case,    wherein:    the first sun gear is fixedly connected to the second sun gear;    the second carrier is fixedly connected to the third ring gear;    the third sun gear always acts as an input element by being fixedly connected to the input shaft;    at least one element of the third carrier and the first ring gear always acts as an output element by being fixedly connected to the at least one output gear;    at least one of the fixedly connected first and second sun gears is variably connected to the input shaft via a first clutch;    the first carrier is variably connected to the input shaft via a second clutch;    the first carrier is variably connected to the transmission case via a first brake and is subject to a stopping operation of the first brake;    at least one of the first and second sun gears is variably connected to the transmission case via a second brake and is subject to a stopping operation of the second brake; and    the second ring gear is variably connected to the transmission case via a third brake and is subject to a stopping operation of the third brake.    
   
   
       2 . The powertrain of  claim 1 , wherein: 
 the at least one output gear comprises first and second output gears; and    the third carrier and the first ring gear are fixedly connected to the first and second output gears, respectively.    
   
   
       3 . The powertrain of  claim 2 , further comprising an output shaft arranged parallel with the input shaft, wherein the first and second output gears are engaged with the output shaft.  
   
   
       4 . The powertrain of  claim 1 , wherein the first, second, and third planetary gearsets are disposed in a sequence of the third planetary gearset, the second planetary gearset, and the first planetary gearset.  
   
   
       5 . The powertrain of  claim 4 , wherein the first and second clutches are disposed opposite of the second planetary gearset with respect to the first planetary gearset.  
   
   
       6 . The powertrain of  claim 4 , wherein the second brake is disposed between the first and the second planetary gearsets.  
   
   
       7 . A six-speed powertrain of an automatic transmission, comprising: 
 a first planetary gear set having first, second, and third operational elements that occupy sequential positions in a lever diagram;    a second planetary gear set having fourth, fifth, and sixth operational elements that occupy sequential positions in a lever diagram;    a third planetary gear set having seventh, eighth, and ninth operational elements that occupy sequential positions in a lever diagram;    an input shaft;    at least one output shaft; and    a transmission case    wherein:    the third operational element is fixedly connected to the sixth operational element;    the fifth operational element is fixedly connected to the ninth operational element;    the seventh operational element always acts as an input element by being fixedly connected to the input shaft;    at lease one operational element of the first and eighth operational elements always acts as an output element by being fixedly connected to the at least one output gear;    at least one of the fixedly connected third and sixth operational elements is variably connected to the input shaft via a first clutch;    the second operational element is variably connected to the input shaft via a second clutch;    the second operational element is variably connected to the transmission case via a first brake and is subject to a stopping operation of the first brake;    at least one of the fixedly connected third and sixth operational elements is variably connected to the transmission case via a second brake and is subject to a stopping operation of the second brake; and    the fourth operational element is variably connected to the transmission case via a third brake and is subject to a stopping operation of the third brake.    
   
   
       8 . The powertrain of  claim 7 , wherein: 
 the at least one output gear comprises first and second output gears; and    the first and eighth operational elements are fixedly connected to the first and second output gears, respectively.    
   
   
       9 . The powertrain of  claim 8 , further comprising an output shaft arranged parallel with the input shaft, wherein the first and second output gears are engaged with the output shaft.  
   
   
       10 . The powertrain of  claim 7 , wherein the first, second, and third planetary gearsets are disposed in a sequence of the third planetary gearset, the second planetary gearset, and the first planetary gearset.  
   
   
       11 . The powertrain of  claim 10 , wherein the first and second clutches are disposed opposite of the second planetary gearset with respect to the first planetary gearset.  
   
   
       12 . The powertrain of  claim 10 , wherein the second brake is disposed between the first and the second planetary gearsets.