Patent ID: 7699744
Filing Date: 2010-04-20
Classification: F16H

Abstract:
1. A multispeed automatic transmission, in particular for automobile vehicles, comprising between an input shaft (E) and an output shaft (S) housed in a casing, a so called double planetary gearset ( 50 ), with four members (A, B, C, D) identified from first to fourth in order of speed, concentric with the output shaft (S), two power paths (P 1 , P 2 ) between the input shaft (E) and the double planetary gearset ( 50 ) and five control devices, which respectively comprise three clutches (C 1 , C 2 , C 3 ) and two brakes (B 1 , B 2 ) and of which the selective operation in pairs determines various transmission ratios between the input shaft (E) and the output shaft (S), the first power path (P 1 ) having a first fixed speed ratio (G 1 ) and comprising the first and the second clutches (C 1 , C 2 ) and the second power path (P 2 ) having a second fixed speed ratio (G 2 ) greater than the first ratio (G 1 ) and in the same direction, and comprising the third clutch (C 3 ), the first member (A) of the double planetary gearset ( 50 ) being connected to the first power path (P 1 ) by the first clutch (C 1 ), the second member (B) being fixed to the output shaft (S), the third member (C) being connected to the second power path (P 2 ) by the third clutch (C 3 ) and held against rotation by the first brake (B 1 ), and the fourth member (D) being connected to the first power path (P 1 ) by the second clutch (C 2 ) and held against rotation by the second brake (B 2 ), wherein which transmission comprises a fourth clutch (C 4 ) connecting the fourth member (D) to the second power path (P 2 ) and constituting a sixth control device, such that selective operation in pairs of the six control devices provides eight forward gears: a first, by the first clutch (C 1 ) and the first brake (B 1 ); a second by the first clutch (C 1 ) and the second brake (B 2 ) ; a third by the first and second clutches (C 1 , C 2 ); a fourth by the first and fourth clutches (C 1 , C 4 ); a fifth by the first and third clutches (C 1 , C 3 ); a sixth in direct drive by the third and fourth clutches (C 3 , C 4 ); a seventh by the second and third clutches (C 2 , C 3 ) ; an eighth by the third clutch (C 3 ) and the second brake (B 2 ); a braked neutral position by the first and second brakes (B 1 , B 2 ); a first reverse drive by the second clutch (C 2 ) and the first brake (B 1 ); and a second reverse drive by the fourth clutch (C 4 ) and the first brake (B 1 ).