Planetary gear transmission systems or components – With means to vary drive ratio or disconnect drive – Plural elements selectively braked
Reexamination Certificate
2000-03-03
2001-10-16
Marmor, Charles A. (Department: 3681)
Planetary gear transmission systems or components
With means to vary drive ratio or disconnect drive
Plural elements selectively braked
C475S280000
Reexamination Certificate
active
06302820
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a planetary speed change transmission with an input shaft, which can be drivingly connected to an output shaft by way of at least one of three planetary gear transmission structures.
In a known planetary type speed change transmission as shown for example in DE 42 38 866 C2 five forward speed ranges including a direct motion transmitting fourth speed range are obtained utilizing six friction engagement elements (three brakes and three clutches).
It is the object of the present invention to provide a planetary-type speed change transmission with at least six forward speed ranges including an upper direct transmission speed range (direct gear), wherein only a minimum of constructive changes with respect to a conventional planetary speed change transmission of this type are required.
SUMMARY OF THE INVENTION
In a planetary speed change transmission wherein an input shaft is drivingly connected, by way of at least one of three planetary gear structures, to an output shaft, five forward gears including a direct gear are obtained with three friction clutches and three friction brake structures. In one embodiment, a sixth forward gear is obtained by providing a disengageable clutch in one of the drive connections between two of the three planetary gear structures. In another embodiment, a sixth forward gear is obtained by auxiliary planetary gears which are engaged by an auxiliary ring gear which is connected to a fourth brake structure for locking the auxiliary ring gear. With this arrangement, a seventh forward gear and a second reverse gear can be obtained.
In the arrangement according to one embodiment of the invention, the object is solved by dividing the coupling connection of the input transmission structure and employing the other two transmission structures (the output transmission structure and the reversing transmission structure) as a common coupled drive for forming at least one additional forward gear. In another embodiment (as defined in claim
3
) the object is solved by using as the input transmission structure a so-called Ravigneaux transmission with an outer additional ring gear, which is in engagement with auxiliary planet gears and which is connected to a separate brake and contributes to the formation of at least one additional forward speed range.
With the planetary speed change transmission as defined in claim
1
an intermediate forward speed range can be provided in that the separation clutch and the reverse gear brake can be disengaged while, in an intermediate gear other than a direct motion transmission (third) gear, the clutch connected to the outer ring gear of the output transmission structure as well as the brake connected to the sun gear of the output transmission structure are engaged.
In another embodiment, an additional lower forward speed range—that is, a transmission with seven forward gears—can be formed by exclusively engaging the brakes connected with the auxiliary ring gear of the input transmission structure and those connected with the sun gear of the output transmission structure whereby the transmission ratio is provided by a multiplying interconnection of the individual transmission ratios of the three transmission structures—thereby providing a first (low) speed range.
With the planetary-type speed change transmission of both embodiments, two reverse speed ranges can be obtained by operating the output transmission structure and the reverse transmission structure in both reversing speed ranges as a common coupled transmission while the reversing brake is engaged and the sun gear of the input gear structure is locked in one of the reverse gear ranges with a partial transmission ratio greater than 1 or, in the other reverse gear range, the input gear structure is at a transmission ratio of 1 by engagement of the brake connected to the sun gear.
In another embodiment of the planetary speed change transmission according to the invention an additional third reverse gear is obtained in that the output gear structure and reverse gear structure operate as a common coupled transmission structure when the reverse brake is engaged and the auxiliary ring gear, which is fixed by braking, is used as the reaction member for the input transmission structure.
In the planetary speed change transmissions of the type with which the present invention is concerned the drive connection between the sun gears of the output transmission structure and the reverse transmission structure is established by engaging a friction clutch connected to these transmission structures.
In the planetary gear speed change transmission of either of the embodiments, the drive connection between the sun gears of the output transmission structure and the reverse transmission structure may be permanent so that a clutch and the respective control equipment can be eliminated.
In the planetary gear speed change transmission according to the invention, the two lowermost speed ranges include a hill-holding function by providing a freewheeling clutch. The hill-holding function may also be effective in the third gear.
Various embodiments of the invention will be described below on the basis of the accompanying drawings.
REFERENCES:
patent: 3946624 (1976-03-01), Murakami et al.
patent: 3971267 (1976-07-01), Murakami et al.
patent: 6071208 (2000-06-01), Koivunen
patent: 28 13 223 (1979-09-01), None
patent: 42 38 856 (1994-05-01), None
patent: 43 13 289 (1994-10-01), None
patent: 197 29 405 (1998-01-01), None
patent: 2272735 (1994-05-01), None
patent: 0118241 (1990-05-01), None
Bach Klaus J.
Daimler-Chrysler AG
Marmor Charles A.
Pang Roger
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