Machine element or mechanism – Gearing – Interchangeably locked
Reexamination Certificate
1999-12-27
2001-04-03
Wright, Dirk (Department: 3681)
Machine element or mechanism
Gearing
Interchangeably locked
Reexamination Certificate
active
06209407
ABSTRACT:
The invention relates to a toothed gear transmission having two partial transmissions disposed parallel to each other in the power flow, and in particular to a toothed gear transmission in which an input shaft is connected to a differential by first and second partial transmissions disposed parallel to each other in the power flow and both having a frictionally engaged load shifting clutch.
DESCRIPTION OF RELATED ART
The manual transmissions with a friction clutch which are normally used in motor vehicles are simple and sturdy, but they have the disadvantage that an interruption in power delivery to the wheels occurs during gear changes. Conventional automatic transmissions with torque converters avoid an interruption of power delivery during gear changes, but due to the torque converter they are less efficient than manual transmissions. Moreover, they are heavier and more costly.
Using toothed gear transmissions having two frictionally engaged load shifting clutches and two partial transmissions disposed parallel to each other in the power flow, it is possible to change gears under load, which is done with an overlap control of the load shifting clutches. This makes it possible to obtain an inexpensive automatic transmission having good efficiency. Generally speaking, the even gear speeds are allocated to one partial transmission and the odd gear speeds are allocated to the other partial transmission.
With this system, shifting is done sequentially under load, and individual gear speeds cannot be skipped without further action, for example a double upshifting or double downshifting.
A toothed gear transmission is described in U.S. Pat. No. 4,658,663, in which an input shaft is connected to an output shaft through first and second partial transmissions disposed parallel to each other in the power flow, and both having a frictionally engaged load shifting clutch. The load shifting clutches can be used to connect concentrically arranged intermediate shafts of the partial transmissions with the input shaft. The intermediate shafts can be effectively connected with the output shaft through transmission constants, through a joint counter shaft disposed parallel to the input shaft, and through toothed gear pairs. The toothed gear pairs for the forward gear speeds I, III, and IV, as well as the toothed gear pair for the reverse gear speed, are located in the first partial transmission. The fourth gear speed is a direct gear speed and can be selected by engaging a shifting element between the output shaft and the intermediate shaft of the first partial transmission.
The second partial transmission includes the toothed gear pairs of forward gear speeds II and V, as well as an additional toothed gear pair, whose gear ratio is equal to that of the third gear speed, whose toothed gear pair belongs to the first partial transmission. In the first partial transmission, a toothed gear clutch for the third gear speed and the direct clutch for the fourth gear speed are combined into a change clutch having a joint synchronizer sleeve, which can be coupled with an idler gear of the toothed gear pair for the third gear speed or with the output shaft.
Double upshifts and double downshifts are possible without interruption of the torque transfer in the described toothed gear transmission, but shifting from the direct fourth gear speed to the first and third gear speeds, whose toothed gear pairs also belong to the first partial transmission, requires intermediate engagement of the supplemental toothed gear pair of the third gear speed. Moreover, a total of seven toothed gear pairs are disposed along the common counter shaft, causing the toothed gear transmission to be relatively long. In addition, the first load shifting clutch of the first partial transmission is always used to start from the first gear speed, which causes greater wear to occur on it than on the second load shifting clutch.
SUMMARY OF THE INVENTION
The invention is a toothed gear transmission easy to construct and having a shortened length, low weight, and high efficiency.
In one embodiment, the invention is a toothed gear transmission with an input shaft connected to a differential by a first and a second partial transmission disposed parallel to each other, which includes two frictionally engaged load shifting clutches coupled respectively to the first and second partial transmissions, two intermediate shafts disposed concentrically to each other and coaxially to the input shaft, each of the intermediate shafts being connectable to the input shaft through one of the load shifting clutches, and at least one toothed gear on each of the two intermediate shafts, the at least one toothed gear being connectable with a first driven shaft disposed parallel to the two intermediate shafts, said first driven shaft providing power to a differential. The invention also includes at least one second driven shaft, parallel to the first driven shaft, having an axis distance between said at least one second driven shaft and one of the two intermediate shafts and the differential that is unequal from a second axis distance between the first driven shaft and one of the two intermediate shafts and the differential. In the invention, one of the at least one toothed gear on each of the two intermediate shafts meshes with a corresponding toothed gear disposed on the first driven shaft and with a toothed gear disposed on at least one of the second driven shafts.
The invention is based on a toothed gear transmission in which an input shaft is connected to a differential by a first and a second partial transmission, which are disposed parallel to each other in the power flow. Each partial transmission has a frictionally engaged load shifting clutch and an intermediate shaft, which are disposed concentrically to each other and coaxially to the input shaft. The respective intermediate shaft can be effectively connected to the input shaft through the load shifting clutch. Each intermediate shaft has at least one toothed gear. At least one intermediate shaft can be effectively connected to a driven shaft, or transmission output shaft, disposed parallel to the intermediate shafts. The driven shaft directly or indirectly drives the differential gear, for example indirectly through a supplemental shaft, a lateral shaft, or a lateral stage. However, it is particularly advantageous for the driven shaft to directly drive a toothed gear of the differential gear, which allows a more compact design and higher efficiency of output, through fewer toothed gear engagements. The differential can be designed as a separate unit or as an integral part of the transmission.
At least one second driven shaft is disposed parallel to the first driven shaft, at an axis distance from the intermediate shafts or the differential that is unequal from the axis distance of the first driven shaft. A minimum of one toothed gear of at least one intermediate shaft meshes both with one toothed gear on the first driven shaft and with one toothed gear on the second driven shaft.
At least one toothed gear, but more advantageously a plurality of toothed gears, are disposed on one or both intermediate shafts, and can be allocated to two gear speeds. With more than two driven shafts, the toothed gears can also be allocated to more than two gear speeds. While allowing a short construction length due to few toothed gear planes, a high number of load shifting capabilities can be achieved by the present transmission. In particular, sequential shifting, double upshifts and double downshifts under load can be achieved, without requiring additional toothed gear planes. Construction space, weight, and cost can be reduced and efficiency can be increased by utilizing the present design. Based on the short construction length that can be achieved, the toothed gear transmission in accordance with the invention is particularly appropriate for transverse installation into a front wheel drive motor vehicle. However, it is also appropriate for longitudinal installation into any type of motor vehicle.
For example, th
Heinzel Markus
Sperber Ralf
Worner Gunter
Daimler-Chrysler AG
Kenyon & Kenyon
Wright Dirk
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