A planetary gear train of automatic transmission may include input shaft, output gear, first to fourth planetary gear sets, first rotating shaft including first sun gear, second rotating shaft including first planet carrier, second ring gear, third planet carrier, and fourth ring gear, third rotating shaft including first ring gear and third ring gear, and selectively connected to transmission housing, fourth rotating shaft including second sun gear, and selectively connected to transmission housing, fifth rotating shaft including second planet carrier, and selectively connected with first rotating shaft and simultaneously and directly connected with input shaft, sixth rotating shaft including third sun gear, seventh rotating shaft including fourth sun gear, and selectively connected with sixth rotating shaft and simultaneously and selectively connected to transmission housing, eighth rotating shaft including fourth planet carrier, and selectively connected with sixth rotating shaft and simultaneously and directly connected with output gear, and six friction elements.

Eleven forward speeds and one reverse speed are achieved by a planetary gear train of an automatic transmission for a vehicle. The planetary gear train includes: an input shaft, an output shaft, four planetary gear sets respectively having three rotational elements, and six control elements for selectively interconnecting the rotational elements and a transmission housing. In particular, the six control elements may be four clutches and two brakes, and the rotational elements of each planetary gear set may be a sun gear, a planet carrier rotatably supporting pinion gears, and a ring gear which internally meshes with the pinion gears.

Eleven forward speeds and one reverse speed are achieved by a planetary gear train of an automatic transmission for a vehicle. The planetary gear train includes: an input shaft, an output shaft, four planetary gear sets respectively having three rotational elements, and six control elements for selectively interconnecting the rotational elements and a transmission housing. In particular, the six control elements may be four clutches and two brakes, and the rotational elements of each planetary gear set may be a sun gear, a planet carrier rotatably supporting pinion gears, and a ring gear which internally meshes with the pinion gears.

Disclosed is an automatic transmission for a hybrid vehicle, the automatic transmission including an input shaft driven by the combustion engine, an output gearwheel, ring gear or pinion, a stationary element such as a casing for example, an electric machine of which the stator is secured to the stationary element, first, second, third, fourth and fifth selective torque transmitting members that can be selectively engaged or activated in order to establish different transmission ratios, a single double planetary gearset of the Ravigneaux type (TPR) the constituent functional elements of which are arranged as two sets of planetary gears connected by the aforementioned members to the input shaft and to the stationary element, the rotor of the electric machine being mounted on a functional element that injects the movement of the gearset.

A method of controlling an automatic transmission is provided. The automatic transmission includes first and second frictional engageable elements and a hydraulic mechanism. The method includes controlling a first hydraulic pressure control valve of the first element to adjust hydraulic pressure to a given value in a first period in response to the gear shift command and increase the hydraulic pressure until first friction plates engaged in a second period, and a second hydraulic pressure control valve of the second element to pre-charge in response to the gear shift command, maintain the hydraulic pressure at a lower value than a highest target value immediately after the pre-charging, and increase the hydraulic pressure until second friction plates engaged immediately after the maintaining the pressure, a time length of the first period being shorter than a time length between a start of the pre-charging and a start of the increasing the pressure.

A method of controlling an automatic transmission is provided. The automatic transmission includes a piston having first and second surfaces opposite from each other, friction plates, engaging and disengaging hydraulic pressure chambers for supplying/discharging hydraulic pressure and directing the piston to push the friction plates to be engaged and disengaged, a hydraulic pressure control valve for supplying/discharging hydraulic pressure to/from the chambers, and first and second oil paths communicating the valve with the chambers. The second surface has a larger area for receiving hydraulic pressure than the first surface. The method includes controlling the disengaged friction plates to be engaged by adjusting the hydraulic pressure to a first pressure in a first period in response to a gear shift command and adjusting the hydraulic pressure to a second pressure in a second period. The first pressure is changed depending on a state of the automatic transmission.

A method of controlling an automatic transmission is provided. The automatic transmission includes a piston having first and second surfaces opposite from each other, friction plates, engaging and disengaging hydraulic pressure chambers for supplying hydraulic pressure and directing the piston to push the friction plates to be engaged and disengaged, a hydraulic pressure control valve for supplying and discharging hydraulic pressure to and from the chambers, and first and second oil paths communicating the valve with the chambers. The second surface has a larger area for receiving hydraulic pressure than that of the first surface. The method includes controlling the friction plates to change from the disengaged state to the engaged state. Controlling the friction plates includes adjusting the hydraulic pressure to a first instruction pressure in a first period in response to a gear shift command, and to a second instruction pressure in a second period.

A transmission is disclosed having an input member, an output member, a plurality of planetary gear sets, a plurality of interconnecting members and a plurality of torque-transmitting mechanisms including a one-way clutch. The plurality of planetary gear sets has first, second and third members. The input member is continuously interconnected with a member of the planetary gear sets. The output member is continuously interconnected with another member of the planetary gear sets. At least eight forward speeds and one reverse speed are produced by the selective engagement of the five torque-transmitting mechanisms.

A transmission is disclosed having an input member, an output member, a plurality of planetary gear sets, a plurality of interconnecting members and a plurality of torque-transmitting mechanisms including a one-way clutch. The plurality of planetary gear sets has first, second and third members. The input member is continuously interconnected with a member of the planetary gear sets. The output member is continuously interconnected with another member of the planetary gear sets. At least eight forward speeds and one reverse speed are produced by the selective engagement of the five torque-transmitting mechanisms.

An electric vehicle transmission (7) includes an input shaft (10), an output shaft (11), a first planetary gear set (P1), a second planetary gear set (P2), and a third planetary gear set (P3). The input shaft (10) is provided for coupling to an electric machine (6). A first shift element (A), a second shift element (B), and a third shift element (C) are provided at least functionally as well. Also disclosed is a drive system (4), a vehicle drive train (5), and an electric vehicle.