Planetary gear transmission systems or components – With means to vary drive ratio or disconnect drive – Carrier braked
Patent
1991-05-31
1993-03-16
Braun, Leslie A.
Planetary gear transmission systems or components
With means to vary drive ratio or disconnect drive
Carrier braked
475271, 475313, F16H 5710
Patent
active
051940566
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to an automatic transmission for motor vehicle with a reduced planetary linkage, whose planet gears of a first and second set of planetary gears mesh with each other and share a common carrier whereby an inner sun gear of the first set of planetary gears rotating together with a hollow shaft and the sun gear of the second set of planetary gears rotating together with an intermediate shaft can be selectively linked to an input shaft via a first clutch and via a second clutch, respectively the intermediate shaft can be braked via a first friction brake and whereby the carrier is connected at its transmission-input side end with a second friction brake and a ring gear of the second set of planetary gears with a driven gear of the automatic transmission, and whereby the intermediate shaft is built as a central solid shaft which traverses the driven gear, and the first friction brake engages the segment of the intermediate shaft extending beyond the drive gear on the transmission-output side.
An automatic transmission of the aforementioned kind is known from U.S. Pat. No. 3,733,928 (FIG. 10). Therein the clutches which can link the hollow shaft and the intermediate shaft with the input shaft and the second friction brake which can lock the carrier of the two sets of planetary gear are arranged outside the radial contour of the planetary linkage, so that a construction with a relatively big axial length results. Besides, this automatic transmission can not be operated in overdrive.
SUMMARY OF THE INVENTION
Therefore, it is the object of the invention to eliminate the mentioned drawbacks, and as a result to reduce the overall dimensions of an automatic transmission of the aforementioned kind and to reduce the related production costs.
This object is attained according to the characterization part of claim 1 due to the fact that the carrier can be connected with the input shaft via a third clutch which is located after the first and the second clutch considered in the direction of the transmission-output side. Thereby, a clearly structured design of the drive connection between input shaft and planetary linkage results, with an actuation of the second set of planetary gears via the second clutch and the central intermediate shaft, an actuation of the first set of planetary gears via the first clutch and the hollow shaft surrounding the intermediate shaft and finally an actuation of the common carrier via the third clutch.
Further advantageous embodiments of the invention are described in the dependent claims 2 to 9. According to claim 2, the second friction brake can be arranged radially with respect to the planetary linkage, which reduces the length of the transmission.
In the embodiment of the invention according to claim 3, the second friction brake and the third clutch are supposed to have a common inner disk carrier. Further, according to claim 4, the first and the third clutch can have a common outer disk carrier opposite with respect to the input shaft. The use of common inner, respectively outer disk carriers leads to a reduction of the production expenditures for the automatic transmission. Besides, for the clutches and friction brakes largely similar friction disks can be used. So for instance according to claim 5, the clutch disks of the first and the third clutch, as well as the disks of the second friction brake are of identical design.
According to claim 6, a supporting element with control cylinders for the first and third clutch, as well as for the second friction brake is provided on the input shaft. According to claim 7, the outer circumference of the supporting element is meant to form the outer disk carrier for the first and third clutch, whereby it corbels in axial directions and on each of the frontal sides of the supporting element a control cylinder for the first and third clutch is provided. This supporting element can double advantageously as an input-side transmission element of the clutches and can receive the control cylinders toget
REFERENCES:
patent: 3733928 (1973-05-01), Uozumi et al.
patent: 4468982 (1984-09-01), Fujita
patent: 4747323 (1988-05-01), Kiuchi et al.
Braun Leslie A.
Dubno Herbert
Trousdell William O.
Zahnradfabrik Friedrichshafen AG
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