Powertrain with a six speed transmission

Details Powertrain with a six speed transmission Powertrain with a six speed transmission

1999-11-22

2001-01-16

Wright, Dirk (Department: 3681)

Planetary gear transmission systems or components

With means to vary drive ratio or disconnect drive

Plural elements selectively braked

Reexamination Certificate

active

06174256

ABSTRACT:

TECHNICAL FIELD
This invention relates to powertrains having multi-speed power transmissions and more particularly to such transmissions having six forward speed ratios.
BACKGROUND OF THE INVENTION
In an effort to improve the overall performance of a vehicle while also reducing the mass of the vehicle, the number of speed ratios available through the transmission is increased. This permits a more efficient use of the engine operating range while also reducing the size of the engine. The increased number of speed ratios allows for a higher low gear ratio which will result in a reduced size torque converter.
The number of forward speed ratios in power transmissions has increased from two to five over a number of years. Many of the five speed transmissions incorporate two or three interconnected simple or compound planetary gear sets and five or six selectively engageable clutches or brakes. These transmissions quite often include one or more bridging clutches when two interconnected planetary gear sets are utilized. One example of this type of power transmission can be seen in U.S. Pat. No. 5,830,102 issued to Coffey on Nov. 3, 1998.
Currently, many manufacturers are considering increasing the number of ratios to six or seven. These transmissions generally contain three planetary gear sets. One such transmission is seen in U.S. Pat. No. 3,946,623 issued Mar. 30, 1976. This prior art transmission incorporates four interconnected planetary gear sets, three clutches and four brakes when more than five speed ratios are to be attained.
A six speed planetary transmission having two simple planetary gear sets is disclosed in U.S. Ser. No. 09/383,429 filed Aug. 27, 1999 and assigned to the assignee of this application. Other six speed planetary transmissions having a simple planetary gear set and a compound planetary gear set are disclosed in co-pending U.S. Ser. Nos. [Attorney Docket Nos. GP-300124, GP-300125 and GP-300126].
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved multi-speed planetary transmission having two planetary gear sets.
In one aspect of the present invention, the transmission has a simple planetary gear set and a compound planetary gear set that are selectively interconnectable. In another aspect of the present invention, the ring gear member of the simple planetary gear set is continuously connected with an output shaft and the planetary carrier assembly member of the compound planetary gear set is continuously connected with an input shaft.
In yet another aspect of the present invention, the sun gear members of the planetary gear sets are selectively interconnected by a selectively engageable torque transmitting mechanism. In still another aspect of the present invention, the planetary carrier assembly member of the compound planetary gear set and the sun gear member of the simple planetary gear set are selectively interconnected by a selectively engageable torque transmitting mechanism.
In a further aspect of the present invention, the ring gear member of the compound planetary gear set and the planetary carrier assembly member of the simple planetary gear set are selectively interconnected by a selectively engageable torque transmitting mechanism. In yet a further aspect of the present invention, the planetary carrier assembly member of the simple planetary gear set is selectively connected with the input shaft by a selectively engageable torque transmitting mechanism. In still a further aspect of the present invention, the above-mentioned four torque transmitting mechanisms and two additional selectively engageable torque transmitting mechanisms are engaged in combinations of three to establish six forward speed ratios and one reverse ratio between the input shaft and the output shaft.


REFERENCES:
patent: 5194055 (1993-03-01), Oshidari
patent: 4-19450 (1992-01-01), None

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