Patent ID: 6790155
Filing Date: 2004-09-14
Classification: F16H

Abstract:
A speed change gear for an automatic transmission, comprising:1) an input portion for inputting a rotation from a power source; 2) an output portion disposed substantially coaxially with the input portion; 3) three planetary gear sets including a first planetary gear set, a second planetary gear set and a third planetary gear set for providing a plurality of power conductive paths to an area defined between the input portion and the output portion; and 4) a first clutch, a second clutch, a third clutch, a first brake and a second brake to be selectively connected and disconnected in such a manner that the three planetary gear sets change a rotation from the input portion at a corresponding gear change ratio by selecting one of the plurality of the power conductive paths, thereby outputting the thus changed rotation to the output portion, the first clutch, the second clutch, the third clutch, the first brake and the second brake making a combination of engagement and disengagement, the combination making a selection from at least six forward gears and one reverse gear, one of the three planetary gear sets being a speed reduction planetary gear set for continuously reducing the inputted rotation and outputting the thus reduced rotation, one of the remaining two planetary gear sets of the three planetary gear sets being a double sun gear planetary gear set which includes; two sun gears, a common pinion meshing with the two sun gears in common, one ring gear meshing with the common pinion, and a planetary carrier for carrying the common pinion in such a manner that the common pinion rotates, the planetary carrier being adapted to input and output a rotation from between the two sun gears via a center member connected to a side member, the other of the remaining two planetary gear sets of the three planetary gear sets being a single pinion planetary gear set which includes; one sun gear, a pinion meshing with the one sun gear, one ring gear meshing with the pinion, and a planetary carrier for carrying the pinion in such a manner that the pinion rotates, the speed change gear for the automatic transmission including: i) a first rotation member including one of the two sun gears of the double sun gear planetary gear set, and being adapted to be held stationary by the second brake; ii) a second rotation member including the other of the two sun gears of the double sun gear planetary gear set, and receiving via the second clutch the reduced rotation from the speed reduction planetary gear set; iii) a third rotation member including an element connected mutually to the double sun gear planetary gear set and the single pinion planetary gear set, and outputting the changed rotation to the output portion; iv) a fourth rotation member receiving via the third clutch the inputted rotation, being adapted to be held stationary by the first brake and including an element in the double sun gear planetary gear set and the single pinion planetary gear set; and v) a fifth rotation member receiving via the first clutch the outputted rotation from the speed reduction planetary gear set, and including an element in the corresponding one of the double sun gear planetary gear set and the single pinion planetary gear set, one of the double sun gear planetary gear set and the single pinion planetary gear set which relates to the second rotation member and the fifth rotation member being disposed nearer to the speed reduction planetary gear set than the other of the double sun gear planetary gear set and the single pinion planetary gear set.