Patent ID: 6808469
Filing Date: 2004-10-26
Classification: F16H

Abstract:
A planetary gear type multiple-step transmission for a vehicle, having seven forward drive positions for driving the vehicle in a forward direction, said seven forward drive positions including a first-speed, a second-speed, a third-speed, a fourth-speed, a fifth-speed, a sixth-speed and a seventh-speed position, said transmission comprising an input rotary member, an output rotary member, a first, a second and a third planetary gear set each including a sun gear, a carrier and a ring gear, and further comprising a first, a second and a third brake, and a first, a second, and a fourth clutch, wherein an improvement comprises:(a) a first, a second, a third, a fourth and a fifth rotary element, each of which is constituted by at least one of the sun gears, carriers and ring gears of said first, second and third planetary gear sets, said first rotary element being selectively brought to a stationary state by said first brake, and said second rotary element being selectively brought to a stationary state by said second brake, while said third rotary element being selectively brought to a stationary state by said third brake, said fifth, rotary element being selectively connected to said input rotary member by said first clutch, said fourth rotary element being connected to said output rotary member; (b) said third rotary element consisting of a first element which is one of said sun gear, carrier and ring gear of said first planetary gear set, a second element which is one of said sun gear, carrier and ring gear of said second planetary gear set, and a third element which is one of said sun ear, carrier and ring gear of said third planetary gear set, said first, second and third elements being rotatable together as a unit by engagement of said fourth clutch, and selectively connected to said input rotary member through said second clutch, and at least one of said sun gears, carriers and ring gears of said first, second and third planetary gear sets which is other than said first, second and third elements being selectively connected to said input rotary member through said first clutch; (c) said fifth-speed position having a speed ratio of 1, while said sixth-speed and seventh-speed positions having speed ratios smaller than 1; and (d) said first-speed position being established by engaging said first clutch and said third brake, or said first and fourth clutches and said third brake, and said second-speed position being established by said first clutch and said second brake, while said third-speed position being established by engaging said first and fourth clutches and said first brake, said fourth-speed position being established by engaging said first and second clutches and said first brake, said fifth-speed position being established by engaging said first, second and fourth clutches, said sixth-speed position being established by engaging said second and fourth clutches and said first brake, said seventh-speed position being established by engaging said second and fourth clutches and said second brake.