Powertrain with a five speed planetary transmission

Planetary gear transmission systems or components – With means to vary drive ratio or disconnect drive – Plural elements selectively braked

Reexamination Certificate

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Details

C475S280000, C475S281000

Reexamination Certificate

active

06287233

ABSTRACT:

TECHNICAL FIELD
This invention relates to multi speed power transmissions and more particularly to five speed planetary gear arrangements having three simple planetary gear sets.
BACKGROUND OF THE INVENTION
In order to improve efficiency and performance, many current vehicles are employing powertrains that include four and five speed planetary transmissions. Some of the available powertrains simply add an overdrive planetary gear set to the transmission in an upstream power flow path relative to a four speed transmission. While effective, these systems require the addition of a brake and a clutch to control the added gear set. Other systems have developed gearing schemes using three planetary gear sets, which include configurations that have not been previously produced, requiring significant engineering design, development and testing prior to release for production use.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved five speed planetary transmission.
In one aspect of the present invention three planetary gear sets are interconnected to provide five forward speed ratios and one reverse ratio. In another aspect of the present invention two of the planetary gear sets are controlled to provide four forward speed ratios and the third planetary gear set cooperates with one of the other planetary gear sets to establish the fifth forward speed ratio.
In yet another aspect of the present invention, the third gear set has a brake member which is engaged to control the fifth forward speed ratio. In still another aspect of the present invention, the third gear set has a member which is driven by the transmission input through a clutch that is active in the highest three forward speed ratios. In a further aspect of the present invention, a transmission having five forward speed ratios is provided through the addition of a planetary gear set and one friction brake assembly to a four speed planetary gear set without changing the interconnections of the four speed planetary gear set.
A five speed transmission is provided through the addition of a simple planetary gear set to a four speed planetary arrangement with minimum investment. The four speed gear arrangement is lengthened to provide space centrally of the two planetary gear sets of the four speed arrangement. The simple planetary gear set and a friction brake are installed in the space provided. The transmission therefore requires a minimum of additional length and only a single friction mechanism is added.


REFERENCES:
patent: 3971267 (1976-07-01), Murakami et al.
patent: 3987690 (1976-10-01), Murakami et al.
patent: 4038888 (1977-08-01), Murakami et al.
patent: 4089239 (1978-05-01), Murakami et al.
patent: 5261862 (1993-11-01), Pierce
patent: 5533945 (1996-07-01), Martin et al.
patent: 5536220 (1996-07-01), Martin

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