Patent ID: 6910985
Filing Date: 2005-06-28
Classification: F16H

Abstract:
1. A gear-operated speed change apparatus for an automatic transmission, comprising: an input portion for inputting a rotation from a drive source; an output portion for outputting a speed-changed rotation; three sets of planetary gear sets; a plurality of members for connecting a plurality of rotary elements like a single unit; four selectively connecting/disconnecting clutches and two selectively fixing brakes positioned between the individual rotary elements of the input portion, the output portion, the members and the three planetary gear sets; and speed change control means for achieving at least seven forward speeds and one reverse speed by engaging/releasing said four clutches and two brakes properly, characterized: in that one planetary gear set of said three planetary gear sets is a speed-reducing device for reducing the speed of the input rotation always; in that one planetary gear set of the remaining two planetary gear sets is a double sun gear type planetary gear set including: two sun gears; a pinion meshing individually with said two sun gears; a carrier having a center member positioned between said two sun gears for inputting or outputting a rotation; and one ring gear meshing with said pinion; in that when the planetary gear set as the speed-reducing device is the first planetary gear set, when said double sun gear type planetary gear set is the third planetary gear set and when the remaining planetary gear set is the second planetary gear set, said second planetary gear set and said third planetary gear set are the planetary gear sets which are constructed of five rotary members including connection members for connecting the rotary members of the second planetary gear set and the rotary members of the third planetary gear set like a single unit: and in that said gear-operated speed change apparatus comprises: a first rotary member having one sun gear of said third planetary gear set and connected to a second brake capable of stopping (or fixing) said one sun gear; a second rotary member having the other sun gear of said third planetary gear set and connected to a second clutch capable of connecting/disconnecting said sun gear and one member of said first planetary gear set selectively; a third rotary member having said connection member and connected to said output portion; a fourth rotary member connected to a third clutch capable of connecting/disconnecting another member of said first planetary gear set and a first brake capable of stopping (or fixing) selectively; a fifth rotary member connected to a first clutch capable of connecting/disconnecting one member of said first planetary gear set selectively; a fourth selectively connecting/disconnecting clutch positioned between the two members of said first rotary member, said third rotary member, said fourth rotary member and said fifth rotary member, between the two members of said second rotary member, said third rotary member, said fourth rotary member and said fifth rotary member, or between one of said first rotary member and said second rotary member and the input portion; and said speed change control means for establishing a 1st speed by the engagement of said first clutch and the first brake, a 2nd speed by the engagement of the first clutch and the second brake, a 3rd speed by the engagement of the first clutch and the second clutch, a 4th speed by the engagement of the first clutch and the third clutch, a 5th speed by the engagement of the third clutch and the fourth clutch, a 6th speed by the engagement of the second clutch and the third clutch, a 7th speed by the engagement of the third clutch and the second brake, and a reverse speed by the engagement of the second clutch and the first brake, thereby to establish at least seven forward speeds and one reverse speed.