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 gearset having operational elements of a first sun gear, a first ring gear, and a first carrier;    a second planetary gearset having operational elements of a second sun gear, a second ring gear, and a second carrier;    a third planetary gearset having operational elements of a third sun gear,    a third ring gear, and a third carrier;    a fourth planetary gearset having operational elements of a fourth sun gear, a fourth ring gear, and a fourth carrier;    an input shaft;    an output gear; and    a transmission case,    wherein:    the first ring gear is fixedly connected to the third carrier and the fourth ring gear;    the first carrier is fixedly connected to the fourth carrier;    the second carrier is fixedly connected to the third ring gear;    the second ring gear is always stationary by being fixedly connected to the transmission case;    the third sun gear always acts as an input element by being fixedly connected to the input shaft;    the third carrier always acts as an output element by being fixedly connected to the output gear;    the fourth sun gear is variably connected to the input shaft via a first clutch;    at least one of the fixedly connected first and fourth carriers is variably connected to the input shaft via a second clutch;    the first sun gear is variably connected to the second sun gear via a third clutch;    at least one of the fixedly connected first and fourth carriers is variably connected to the transmission case via a first brake and is subject to a stopping operation of the first brake; and    the first sun gear is variably connected to the transmission case via a second brake and is subject to a stopping operation of the second brake.    
   
   
       2 . The powertrain of  claim 1 , wherein the first, second, third, and fourth planetary gearsets are disposed in a sequence of the second planetary gearset, the first planetary gearset, the fourth planetary gearset, and the third planetary gearset.  
   
   
       3 . The powertrain of  claim 2 , wherein: 
 the first ring gear of the first planetary gearset is integrally formed with the fourth ring gear of the fourth planetary gearset; and    the first carrier of the first planetary gearset is integrally formed with the fourth carrier of the fourth planetary gearset,    such that the first and fourth planetary gearsets form a compound planetary gearset.    
   
   
       4 . The powertrain of  claim 3 , wherein 
 the input shaft is disposed in a same direction of the output gear with respect to the third planetary gearset;    one of the first and second clutches is disposed toward the input shaft with respect to the third planetary gearset; and    another one of the first and second clutches is disposed opposite of the input shaft with respect to the second planetary gearset.    
   
   
       5 . The powertrain of  claim 4 , wherein: 
 the first clutch is disposed toward the input shaft with respect to the third planetary gearset; and    the second clutch is disposed opposite of the input shaft with respect to the second planetary gearset.    
   
   
       6 . The powertrain of  claim 3 , wherein: 
 the input shaft is disposed in a same direction of the output gear with respect to the third planetary gearset; and    both of the first and second clutches are disposed toward the input shaft with respect to the third planetary gearset.    
   
   
       7 . The powertrain of  claim 6 , wherein the first and second clutches are disposed in a sequence of the first clutch and the second clutch, in a direction from the third planetary gearset to the input shaft.  
   
   
       8 . The powertrain of  claim 6 , wherein the first and second clutches are disposed in a sequence of the second clutch and the first clutch, in a direction from the third planetary gearset to the input shaft.  
   
   
       9 . The powertrain of  claim 3 , wherein: 
 the input shaft is disposed opposite of the output gear with respect to the second planetary gearset; and    both of the first and second clutches are disposed toward the input shaft with respect to the second planetary gearset.    
   
   
       10 . The powertrain of  claim 9 , wherein the first and second clutches are disposed in a sequence of the first clutch and the second clutch, in a direction from the second planetary gearset to the input shaft.  
   
   
       11 . The powertrain of  claim 1 , further comprising a one way clutch disposed in parallel with the first brake.  
   
   
       12 . The powertrain of  claim 1 , wherein the first and second brakes are wet-type multi-plate brakes or band brakes.  
   
   
       13 . A six-speed powertrain of an automatic transmission, comprising: 
 a first planetary gearset having first, second, and third operational elements that occupy sequential positions in a lever diagram;    a second planetary gearset having fourth, fifth, and sixth operational elements that occupy sequential positions in a lever diagram;    a third planetary gearset having seventh, eighth, and ninth operational elements that occupy sequential positions in a lever diagram;    a fourth planetary gearset having tenth, eleventh, and twelfth operational elements that occupy sequential positions in a lever diagram;    an input shaft;    an output shaft; and    a transmission case,    wherein:    the first operational element is fixedly connected to the eighth operational element and the tenth operational element;    the second operational element is fixedly connected to the eleventh operational element;    the fifth operational element is fixedly connected to the ninth operational element;    the fourth operational element is always stationary by being fixedly connected to the transmission case;    the seventh operational element always acts as an input element by being fixedly connected to the input shaft;    the eighth operational element always acts as an output element by being fixedly connected to the output gear;    the twelfth operational element is variably connected to the input shaft via a first clutch;    at least one of the fixedly connected second and eleventh operational elements is variably connected to the input shaft via a second clutch;    the third operational element is variably connected to the sixth operational element via a third clutch;    at least one of the fixedly connected second and eleventh operational elements is variably connected to the transmission case via a first brake and is subject to a stopping operation of the first brake; and    the third operational element is variably connected to the transmission case via a second brake and is subject to a stopping operation of the second brake.    
   
   
       14 . The powertrain of  claim 13 , wherein the first, second, third, and fourth planetary gearsets are disposed in a sequence of the second planetary gearset, the first planetary gearset, the fourth planetary gearset, and the third planetary gearset.  
   
   
       15 . The powertrain of  claim 14 , wherein: 
 the first operational element of the first planetary gearset is integrally formed with the tenth operational element of the fourth planetary gearset; and    the second operational element of the first planetary gearset is integrally formed with the eleventh operational element of the fourth planetary gearset,    such that the first and fourth planetary gearsets form a compound planetary gearset.    
   
   
       16 . The powertrain of  claim 15 , wherein: 
 the input shaft is disposed in a same direction of the output gear with respect to the third planetary gearset;    one of the first and second clutches is disposed toward the input shaft with respect to the third planetary gearset; and    another of the first and second clutches is disposed opposite of the input shaft with respect to the second planetary gearset.    
   
   
       17 . The powertrain of  claim 16 , wherein: 
 the first clutch is disposed toward the input shaft with respect to the third planetary gearset; and    the second clutch is disposed opposite of the input shaft with respect to the second planetary gearset.    
   
   
       18 . The powertrain of  claim 15 , wherein: 
 the input shaft is disposed in a same direction of the output gear with respect to the third planetary gearset; and    both of the first and second clutches are disposed toward the input shaft with respect to the third planetary gearset.    
   
   
       19 . The powertrain of  claim 18 , wherein the first and second clutches are disposed in a sequence of the first clutch and the second clutch, in a direction from the third planetary gearset to the input shaft.  
   
   
       20 . The powertrain of  claim 18 , wherein the first and second clutches are disposed in a sequence of the second clutch and the first clutch, in a direction from the third planetary gearset to the input shaft.  
   
   
       21 . The powertrain of  claim 15 , wherein: 
 the input shaft is disposed opposite of the output gear with respect to the second planetary gearset; and    both of the first and second clutches are disposed toward the input shaft with respect to the second planetary gearset.    
   
   
       22 . The powertrain of  claim 21 , wherein the first and second clutches are disposed in a sequence of the first clutch and the second clutch, in a direction from the second planetary gearset to the input shaft.  
   
   
       23 . The powertrain of  claim 13 , further comprising a one way clutch disposed in parallel with the first brake.  
   
   
       24 . The powertrain of  claim 13 , wherein the first and second brakes are wet-type multi-plate brakes or band brakes.