Patent ID: 6875149
Filing Date: 2005-04-05
Classification: F16H

Abstract:
1. An automatic transmission, comprising: a first planetary gear set; a second planetary gear set; a first clutch; a second clutch; a first brake; a second brake; a third brake; a non-rotatable portion; an input portion for inputting rotations; and an output portion for outputting rotations transmitted from the input portion, wherein a planetary gear of the first planetary gear set and a planetary gear of the second planetary gear set are integrally coupled with each other such that the planetary gears rotate about a common axis; a carrier of the first planetary gear set and a carrier of the second planetary gear set are integrally coupled with each other; and a sun gear and a ring gear of the first planetary gear set, a sun gear and a ring gear of the second planetary gear set, and the coupled carriers of the first and second planetary gear sets form a first rotational element, a second rotational element, a third rotational element, a fourth rotational element, and a fifth rotational element, and wherein the first rotational element is selectively connectable to the non-rotatable portion via the third brake so that rotation of the first rotational element is stopped by engaging the third brake; the second rotational element is selectively connectable to the non-rotatable portion via the second brake so that rotation of the second rotational element is stopped by engaging the second brake; the third rotational element is selectively connectable to the input portion via the second clutch and is selectively connectable to the non-rotatable portion via the first brake so that rotation of the third rotational element is stopped by engaging the first brake; the fourth rotational element is coupled with the output portion; and the fifth rotational element is selectively connectable to the input portion via the first clutch, and wherein engagement of the first clutch and the first brake establishes a first gear speed having a largest transmission gear ratio; engagement of the first clutch and the second brake establishes a second gear speed having a transmission gear ratio smaller than the transmission gear ratio of the first gear speed; engagement of the first clutch and the third brake establishes a third gear speed having a transmission gear ratio smaller than the transmission gear ratio of the second gear speed; engagement of the first clutch and the second clutch establishes a fourth gear speed having a transmission gear ratio smaller than the transmission gear ratio of the third gear speed; and engagement of the second clutch and the third brake establishes a fifth gear speed having a transmission gear ratio smaller than the transmission gear ratio of the fourth gear speed.