Planetary gear transmission systems or components – With means to vary drive ratio or disconnect drive – Plural elements selectively braked
Reexamination Certificate
1999-12-17
2001-09-11
Bonck, Rodney H. (Department: 3681)
Planetary gear transmission systems or components
With means to vary drive ratio or disconnect drive
Plural elements selectively braked
C475S325000
Reexamination Certificate
active
06287234
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a geartrain, and more specially, to a geartrain for a five forward speeds and one reverse speed automatic transmission, which can be designed to be lightweight and compact in size by combining a clutch, brake, and planetary gearset efficiently.
(b) Description of the Related Art
Generally, an automatic transmission system controls each element of single planetary gearsets which are connected to either operative or inoperative friction elements by a hydraulic control system of a transmission control unit (TCU), so that the automatic transmission system automatically controls shift ratios.
A geartrain is typically described with a combination of planetary gearsets and friction elements to realize shift ratios.
The above described geartrain is variously composed according to shift ratios and the geartrain is composed of primary and sub shifts combining seven clutches and brakes and three single planetary gearsets especially for realizing five forward speeds and one reverse speed.
However, the above described geartrain for an automatic transmission becomes large in size and heavy because of the use of heavy and large-size clutches and brakes and a plurality of inoperative friction elements, which results in power loss.
SUMMARY OF THE INVENTION
The present invention has been made in an effort to solve the above problems associated with the above described conventional geartrain.
It is an object of the present invention to provide a geartrain for an automatic transmission which can be designed to be lightweight and compact in size and improve a power efficiency while realizing a five forward speeds and one reverse speed by three single planetary gearsets and a number of friction elements.
According to a feature of the present invention, a geartrain for an automatic transmission comprises three single planetary gearsets which variably or fixedly connect the specific elements to each other, and a number of friction elements which variably connect a input shaft, each element of said single planetary gearsets, and a transmission housing for outputting five forward speeds and one reverse speed.
More specially, a geartrain for an automatic transmission comprises as follows:
a first single planetary gearset comprising a first element being variably connected to an input shaft, a second element transferring power to a transfer shaft, and a third element being variably connected to the input shaft and selectively connected to said first or said second element;
a second single planetary gearset comprising a first element being fixedly connected to an element of said first single planetary gearset, a second element being variably connected to an transmission housing, and a third element being fixedly connected to another element of the first single planetary gearset and transferring power to an transfer shaft;
a third single planetary gearset comprising a first element being variably connected to said input shaft, a second element being fixedly connected to an element of the second single planetary gearset, and a third element transferring power to the transfer shaft;
a first, second, and third clutch means for variably connecting specific elements of first, second, and third single planetary gearsets to the input shaft or for variably connecting specific elements of first and third single planetary gearsets to each other so that the above described first, second, and third single planetary gearsets being variably and fixedly connected transform an input of the input shaft into five forward speeds and one reverse speed to the transfer shaft; and
a first brake means for variably connecting a specific element of the second single planetary gearset to the transmission housing.
As describe above, a geartrain for an automatic transmission of the present invention selectively operates and releases the first, second, and third clutches and the first brake by a hydraulic control system and control the first, second, and third single planetary gearsets for outputting five forward speeds and one reverse speed.
That is, in the forward first speed, the first clutch and the first brake are operated respectively; in the forward second speed, the second clutch and the first brake are operated respectively; in the forward third speed, the first and second clutches are operated respectively; in the forward fourth speed, the second and third clutches are operated respectively; in the forward fifth speed, the first and third clutches are operated respectively; in the reverse first speed, the third clutch and the first brake are operated respectively.
REFERENCES:
patent: 3820418 (1974-06-01), Ott
patent: 5098357 (1992-03-01), Asada et al.
patent: 5533945 (1996-07-01), Martin et al.
patent: 5772552 (1998-06-01), Ibaraki et al.
patent: 8-261301 (1996-10-01), None
Bonck Rodney H.
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Hyndai Motor Company
Parekh Ankur
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