Patent ID: 7238141
Filing Date: 2007-07-03
Classification: F16H

Abstract:
1. A seven-speed powertrain for an automatic transmission comprising: a first single pinion planetary gear set having a first sun gear, a first ring gear, and a first planet carrier as an operating member thereof; a second single pinion planetary gear set having a second sun gear, a second ring gear, and a second planet carrier as an operating member thereof; and a third single pinion planetary gear set having a third sun gear, a third ring gear, and a third planet carrier as an operating member thereof, wherein the first, second, and third single pinion planetary gear sets are arranged on an input shaft and combined by a plurality of frictional elements comprising first, second, and third brakes, and first, second, and third clutches, and wherein: the first ring gear is fixedly connected to the second planet carrier, the second ring gear is fixedly connected to the third planet carrier, and the third ring gear is fixedly connected to the first planet carrier; the second planet carrier is variably connected to the input shaft via the first clutch that operates at a fourth forward speed, a sixth forward speed, and a seventh forward speed; the first sun gear is variably connected to the input shaft via the second clutch that operates in a fifth and sixth forward speed and is variably connected to a transmission case via a first brake that operates at a first, second, third, and fourth forward speed; the second sun gear is fixedly connected to the input shaft to operate always as an input element; the third planet carrier is variably connected to the transmission case via the second brake that operates at a reverse speed and a one-way clutch that operates at a first forward speed; the third sun gear is variably connected to the input shaft via the third clutch that operates at the third forward speed and at the reverse speed, and is variably connected to the transmission case via the third brake that operates the second forward speed, the fifth forward speed, and the seventh forward speed; and the third ring gear is connected to an output gear.