Patent ID: 9599197
Date: 2017-03-21
CPC Classifications: F16H

Claim:
1. A planetary gear train of an automatic transmission for a vehicle, comprising: an input shaft receiving torque of an engine; an output shaft outputting changed torque; a first planetary gear set including a first rotation element, a second rotation element, and a third rotation element; a second planetary gear set including a fourth rotation element, a fifth rotation element, and a sixth rotation element; a third planetary gear set including a seventh rotation element, an eighth rotation element, and a ninth rotation element; a fourth planetary gear set including a tenth rotation element, an eleventh rotation element, and a twelfth rotation element; and six friction elements disposed between at least one rotation element among the twelve rotation elements and another rotation element or a transmission housing, wherein the input shaft is continuously connected to the second rotation element, the output shaft is continuously connected to the eleventh rotation element, the first rotation element is continuously connected to the fourth rotation element, the fifth rotation element is continuously connected to the eighth rotation element, the sixth rotation element is continuously connected to the eleventh rotation element, the ninth rotation element is continuously connected to the tenth rotation element, the second rotation element is selectively connected to the third rotation element, three friction elements among the six friction elements are operated at each speed stage.