Machine element or mechanism – Gearing – Plural power paths to and/or from gearing
Patent
1986-12-30
1989-04-25
Braun, Leslie A.
Machine element or mechanism
Gearing
Plural power paths to and/or from gearing
74753, F16H 5710, F16H 344
Patent
active
048236411
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a national phase application corresponding to PCT/EP/86/00236 filed Apr. 19, 1986 and based, in turn, on PCT/EP85/00200 filed May 4, 1985 under the International Convention.
FIELD OF THE INVENTION
Our present invention relates to a planetary gear transmission and, more particularly, to a four or five-speed transmission which can be of highly compact construction.
BACKGROUND OF THE INVENTION
SAE 750381, pages 4 and 12, describes a four-speed transmission which consists of a Simpson-type planetary gear set followed by a simple planet set arrayed thereafter, and which has two clutches and three brakes. A hydrodynamic unit is provided ahead of the transmission.
Transmissions of this type with a Simpson-type planetary gear set as a three-speed transmission unit have proven themselves particularly in transmissions to be shifted automatically.
However, their construction is complicated and the cost of manufacture is high. The overall length of the transmission is not satisfactory, and the positions of the clutches and brakes are not optimal with respect to the planetary sets.
OBJECTS OF THE INVENTION
It is, therefore, an object of the invention to provide an improved planetary-gear transmission, which can be manufactured more economically, facilitates more favorable speed ratios including an overdrive, is comparatively short, and can be expanded with respect to the number of speeds, particularly to a four-speed embodiment, with ease.
SUMMARY OF THE INVENTION
This object is achieved with a planetary gear speed-change transmission for a motor vehicle with positively connected partial drives and at least one hydrodynamic unit positioned at the input to the transmission, a gear ratio sequence decreasing from the highest speed and with shift couplings/clutches and brakes for the automatic shifting of at least four forward speeds. According to the invention the first two gear sets are realized in the form of a reduced/connecting drive with a compound planet set where the first planets extend over both gear sets and the second planets are arrayed only in the first gear set and mesh with a breakable internal gear and the first planets. In the second gear set there are also arrayed a sun gear and an internal gear and a common planet carrier is connected with the planet carrier of the first gear set and the third gear set forming a further speed, and can be connected with the output shaft in a positive manner.
The common planet carrier yields in connection with a further gear set a particularly favorable sequence of speeds and the fixed connection of the transmission output shaft with the two planet carriers permits a simple and short transmission construction. Interconnecting gear for the connection of the planet carriers with one another and with the output shaft is not necessary, and only one bearing is needed for the output shaft.
According to a feature of the invention, the third gear set is a simple planet set with a sun gear, an internal gear and a simple planet. Alternatively, the third gear set is formed by a stepped planet set with a compound planet and two sun gears. When a step planet is provided in the gear train, in addition to the favorable sequence of speeds, an overdrive as is frequently desired, can be provided. In this embodiment, the fixed connection of the two planet carriers to the output shaft can also be retained, so that the advantages previously described will result. This allows an overdrive construction with the favorable ratio of 0.75 and only one shafting element without essential modification of the basic four-speed transmission.
The direct-drive construction wherein the third gear set is a simple planet set, is particularly suited for an expansion to a five-speed transmission, where the fifth speed is an overdrive. The advantages of the five-speed construction reside particularly in the straightforward construction. Thus the internal gear of the third gear set can be lengthened, retaining the number of teeth, and utiliz
REFERENCES:
patent: 3030824 (1962-04-01), Moore
patent: 3088339 (1963-05-01), Black
patent: 3209618 (1965-10-01), Schwab
patent: 3355966 (1967-12-01), Boehm
patent: 3365985 (1968-01-01), Johnson
patent: 3722323 (1973-03-01), Welch
patent: 4089238 (1978-05-01), Forster et al.
patent: 4143562 (1979-03-01), Murakami
patent: 4229996 (1980-10-01), Hildebrand
patent: 4417484 (1983-11-01), Gaus et al.
Automatic Transmission for Passenger Coaches by R. H. Schaefer and D. L. Robinson, ASE, Detroit, Mich., Feb. 24-28, 1975, No. 750381 (Society of Automotive Engineers, Inc.).
Kuhn Walter
Muller Hans
Braun Leslie A.
Dubno Herbert
Novais David
Zahnradfabrik Friedrichshafen AG
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