Multi speed power transmission

Details Multi speed power transmission Multi speed power transmission

1999-10-22

2001-04-17

Marmor, Charles A. (Department: 3681)

Planetary gear transmission systems or components

With means to vary drive ratio or disconnect drive

C475S275000, C475S280000

Reexamination Certificate

active

06217474

ABSTRACT:

TECHNICAL FIELD
This invention relates to power transmissions and more particularly to multi speed power transmissions having three simple planetary gear sets.
BACKGROUND OF THE INVENTION
Many of the current automobile manufacturers are using five speed automatic transmissions that incorporate three planetary gear sets. There has also been a number of recently issued patents issued that describe five speed automatic transmissions having three planetary gear sets; and some describing five speed automatic transmissions having two planetary gear sets that include a continuous drive connection and a selective drive connection between the planetary gear sets. Most of the two planetary gear set transmissions incorporate a simple planetary gear set and a compound planetary gear set. The transmissions having three simple planetary gear sets have at least one continuous drive connection uniting a member of each planetary gear set; or a clutch mechanism that will unite the three gear sets. These multi speed power transmissions include at least one selectively engageable torque transmitting mechanism for each of the forward speeds. In other words, a five speed transmission has five selectively engageable torque transmitting mechanisms. Generally, the torque transmitting mechanisms include three clutches and two brakes
A transmission described in U.S. Pat. No. 4,070,927, issued to Polak on Jan. 31, 1978, has three simple planetary gear sets controlled by five torque transmitting mechanisms to produce six forward speed ratios and a reverse ratio. This transmission produces three underdrive ratios, a direct drive ratio and two overdrive ratios in the forward direction. To provide a seventh speed, Polak incorporates an additional planetary gear set.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved multi speed power transmission having three simple planetary gear sets.
In one aspect of the invention, the three simple planetary gear sets are controlled by a plurality of selectively engageable torque transmitting mechanisms to provide seven forward speed ratios, a reverse ratio, and a neutral condition. In another aspect of the present invention, the seven forward speed ratios, with coast braking, and the reverse ratio are established through the judicious engagement of six torque transmitting mechanisms.
In yet another aspect of the present invention, a one-way torque transmitting device provides the reaction grounding mechanism for the first and second forward ratios when coast braking is not desired. In still another aspect of the present invention, two of the planetary gear sets each have a member connected for continuous rotation with an output shaft and each have another member connected for common rotation.
In yet still another aspect of the present invention, each of the planetary gear sets has at least one member connectable with an input shaft through a selectively engageable clutch mechanism. In a further aspect of the present invention, the third of the planetary gear sets has a member connected for common rotation with a member of one of the other two planetary gear sets and with a selectively engageable friction brake. In yet a further aspect of the present invention, the three planetary gear sets are controlled by the selectively engageable torque transmitting mechanisms to produce four underdrive ratios, a direct drive ratio and two overdrive ratios.
In still a further aspect of the present invention, the three planetary gear sets can be controlled to provide a six speed transmission having four underdrive ratios and one overdrive ratio, a six speed transmission having three underdrive ratios and two overdrive ratios, and a five speed transmission having four underdrive ratios and a direct drive ratios with only two selectively friction engageable clutches and three selectively engageable friction brakes. In a yet still further aspect of the present invention, one of the planetary gear sets has one member continuously drive connected with the input shaft as well as one member selectively connectable with the input shaft through a friction clutch.


REFERENCES:
patent: 5049116 (1991-09-01), Asada
patent: 5165308 (1992-11-01), Asada et al.
patent: 6053839 (2000-04-01), Baldwin et al.
patent: 6071208 (2000-06-01), Koivunen

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