| 摘要 |
PROBLEM TO BE SOLVED: To enhance the flexibility of setting the ratio of respective shift stages, while enhancing mechanical transmission efficiency, by eliminating a Ravigneau type shifting planetary gear unit from a shifting planetary gear unit. SOLUTION: An automatic transmission T of forward 7 stages and backward 1 stage has a single pinion type speed reduction planetary gear unit PUr, the shifting planetary gear unit PUs constituted by combining first and second planetary gear units PU1 and PU2 of a single pinion type in both and having four differential rotary elements, and six frictional engaging elements Ca, Cb, Cc, C1, B1 and B2 of a wet multiple disc type or a band brake type. The shift stage of forward 1 speed-forward 7 speed and backward 1 speed is established by selectively fastening three pieces among the six frictional engaging elements. Since a Ravigneau type planetary gear unit is not used, the mechanical transmission efficiency is enhanced, and the flexibility of setting the ratio of the respective shift stages can also be enhanced. COPYRIGHT: (C)2009,JPO&INPIT
|
