Automatic transmissions, particularly for motor vehicles, comprise planetary gear sets according to the prior art that are engaged by means of friction or shift elements such as clutches and brakes and are typically connected to a startup element, such as a hydrodynamic torque converter or a hydraulic coupling, subject to a slip effect and optionally equipped with a lock-up clutch.
These types of automatic transmissions are described often in the prior art and subject to continuous further development and improvement. Thus, these transmissions have a sufficient number of forward gears as well as at least one reverse gear and a gear ratio that is very well-suited for motor vehicles with a very high overall spread as well as favorable progressive ratios. Furthermore, the transmissions should enable a high starting ratio in the forward direction and contain a direct drive. In addition, automatic transmissions should require less construction costs and a small number of shift elements, in which, with the sequential shifting method, only one shift element should be engaged and one shift element should be disengaged.
An automatic transmission of this type is known to the applicant from DE 199 12 480 B4, for example. It comprises three carrier planetary gear sets as well as three brakes and two clutches for engaging six forward gears and one reverse gear, one drive shaft and one output shaft, in which the carrier of the first planetary gear set is permanently connected to the ring gear of the second planetary gear set and the carrier of the second planetary gear set is permanently connected to the ring gear of the third planetary gear set and the drive shaft is directly connected to the sun gear of the second planetary gear set.
Furthermore, with the known transmission, it is provided that the drive shaft can be connected to the sun gear of the first planetary gear set via the first clutch and can be connected to the carrier of the first planetary gear set via the second clutch, in which the sun gear of the first planetary gear set can be connected to a housing of the transmission via the first brake and the carrier of the first planetary gear set can be connected to the housing of the transmission via the second brake, in which the sun gear of the third planetary gear set can be connected to the housing of the transmission via the third brake. The output shaft of the transmission is permanently connected to the carrier of the third planetary gear set and the ring gear of the first planetary gear set.
USPTO Backgrounds
USPTO Backgrounds