Power train with a reduced number of clutches

Details Power train with a reduced number of clutches Power train with a reduced number of clutches

1997-04-23

1998-04-28

Wright, Dirk

Planetary gear transmission systems or components

With means to vary drive ratio or disconnect drive

Plural elements selectively braked

F16H 364

Patent

active

057438250

DESCRIPTION:

BRIEF SUMMARY
FIELD TO THE INVENTION

The present invention is directed to an automatic transmission for use in an automobile; and, more particularly, to a power train of the type which comprises a compound planetary gear set arranged along a first transmission shaft for providing first to fourth forward drive ratios and one reverse drive ratio and a simple planetary gear set disposed on a second transmission shaft for accomplishing a fifth forward drive ratio, wherein the compound planetary gear set is operatively coupled to the simple planetary gear set through the use of a chain and sprocket coupler.


DESCRIPTION OF THE PRIOR ART

As is well-known in the art, the drivability or fuel economy of a motor vehicle can be heavily affected by the characteristics of its transmission, especially in case of an automatic power transmission. Hence, a variety of automatic transmissions has been developed in an effort to improve the performance characteristics, e.g., drivability or fuel economy of the automotive vehicle. Conventionally, the automatic transmission includes a power or gear train having at least two simple or one compound planetary gear set whose rotary movement is under close control of hydraulically operated clutches and brakes. As used herein, the term power train is interchangeable with the gear train. Similarly, the terms planet gear and pinion gear, and the terms annulus gear and ring gear are used synonymously. A hydraulic control system is employed to have the clutches and the brakes selectively engaged or released, thereby controlling the rotary movement of the planetary gear set in such a manner as to provide a desired drive ratio.
Since the advent of the automatic transmission, a great deal of efforts has been made to provide a compact, reliable, cost-effective gear train which satisfies various operating requirements. Recent trend has been to equip the automatic transmission with a gear train capable of providing five or more forward drive ratios and at least one reverse drive ratio.
For instance, U.S. Pat. No. 5,030,187 issued to Asada on Jul. 9, 1991 discloses an automatic transmission having a gear train which comprises first, second and third single-pinion planetary gear sets. The ring gear of the first single-pinion planetary gear set is connected integrally or selectively to the carrier of the second single-pinion planetary gear set. The carrier of the first single-pinion planetary gear set is connected integrally or selectively to the carrier of the third single-pinion planetary gear set; and the sun gear of the second single-pinion planetary gear set is connected integrally or selectively to the sun gear of the third single-planetary gear set. The automatic transmission disclosed in the '187 patent is capable of operating in any one of at least five forward gears and one reverse gear.
Another type of automatic transmission is taught in U.S. Pat. No. 5,057,063 issued to Asada et al on Oct. 15, 1991 wherein there is provided a gear train for changing the rotational speed of an input shaft which consists of first and second single pinion type planetary gear sets and a third double pinion type planetary gear set. A sun gear of the first planetary gear set is normally or selectively connected to a carrier and a sun gear of the second planetary gear set; a carrier of the first planetary gear set is normally or selectively connected to a carrier of the third planetary gear set; the carrier of the second planetary gear set is normally or selectively connected to a sun gear of the third planetary gear set; a ring gear of the second planetary gear set is normally or selectively connected to a ring gear of the third planetary gear set; the input shaft is selectively connected to either one or both of the sun gear and the ring gear of the first planetary gear set; and the output shaft is connected to the sun gear of the third planetary gear set, whereby at least five forward speeds and one reverse speed are established.
U.S. Pat. No. 5,090,952 issued to Asada on Feb. 25, 1992 teaches a gear train for changin

REFERENCES:
patent: 4747323 (1988-05-01), Kiuchi et al.
patent: 4892011 (1990-01-01), Nishida et al.
patent: 5030187 (1991-07-01), Asada
patent: 5057063 (1991-10-01), Asada et al.
patent: 5090952 (1992-02-01), Asada
patent: 5091854 (1992-02-01), Yoshimura et al.
patent: 5213552 (1993-05-01), Ito

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