Machine element or mechanism – Gearing – Interchangeably locked
Reexamination Certificate
1999-12-23
2001-06-26
Wright, Dirk (Department: 3682)
Machine element or mechanism
Gearing
Interchangeably locked
Reexamination Certificate
active
06250171
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This invention relates to the following co-pending application, which is incorporated by reference:
“Gear Changing Transmission Having Two Transmission Groups Arranged Parallel to One Another in the Power Flow”, Ser. No. 09/471,559, filed Dec. 23, 1999.
FIELD OF THE INVENTION
The invention concerns a variable-ratio gear transmission (gearwheel manual transmission).
BACKGROUND OF THE INVENTION
In the known variable-ratio gear transmission of the type mentioned above (U.S. Pat. No. 4,658,663), the gear stages for the gears I, III, IV, and R are assigned to the first partial transmission, and the gear stages for the gears II and V and the auxiliary gear stage having the gear ratio of gear III are assigned to the second partial transmission, gear IV being designed as a direct gear and able to be shifted using gear III using a manual transmission clutch in the first partial transmission, as is also provided for the auxiliary gear stage and the gear stage of gear V upon the engagement of a manual transmission clutch in the second partial transmission. For the gear stages assigned to the five forward gears and one reverse gear, for the auxiliary gear stage and the gear constant, a total of seven gear sets are supported next to each other along the common counter shaft, so that this known variable-ratio gear transmission comes to be relatively large in the directions of the transmission shafts.
SUMMARY OF THE INVENTION
The objective underlying the invention is essentially to create a variable-ratio gear transmission of the species for transverse installation in a front-wheel-drive motor vehicle, requiring relatively little space in the directions of the transmission shafts.
The objective mentioned is advantageously achieved in a variable-ratio gear transmission according to the invention, the transmission having two gear stages, which in the known variable-ratio gear transmission are arranged next to each other, being replaced by a single gear set assigned to the two partial transmissions using two gear-type clutches, which in the known transmission are also necessary, so that space is saved in the direction of the transmission shafts.
In the known variable-ratio gear transmission, the important triple shifts between gears II and V are not possible because the assigned gear stages belong to the same second partial transmission, so that power shifts cannot be carried out using overlap (override) control without interruptions in the propulsive power.
In the variable-ratio gear transmission according to the invention, this disadvantage is avoided by a further auxiliary gear stage wherein the auxiliary gear stage is assigned to the first partial transmission.
In the known variable-ratio gear transmission, the important direct shifts between gear III and gear IV are not possible because both the assigned gear stage of gear III as well as the direct coupling of the direct gear=gear IV belong to the same first partial transmission.
In the variable-ratio gear transmission according to the invention, this disadvantage is avoided by the gear stages being assigned to the two partial transmissions in accordance with the changing sequence of gears (I-VI).
In the known variable-ratio gear transmission, the important triple shifts between gears I and IV are not possible because the assigned gear stages belong to one and the same first partial transmission.
In the variable-ratio gear transmission according to the invention, all double and triple shifts are made possible by selecting the gear ratios of the two auxiliary gear stages (ZIII* and ZIV*) to belong to two adjacent gears (III and IV), it being possible to increase the number of gears to six forward gears.
In the variable-ratio gear transmission according to the invention, the installation space in the directions of the transmission shafts is even further significantly reduced by providing an auxiliary countershaft for the auxiliary gear stage (IV*) of the first partial transmission, the auxiliary countershaft being connected to the output shaft by an auxiliary, permanently effective gear constant. Moreover, the installation space in the directions of the transmission shafts is even further significantly reduced by providing the gearwheel, arranged on the auxiliary countershaft, of the auxiliary gear stage (ZIV*) of the first partial transmission configured as an idler which can be coupled to the auxiliary countershaft by a third gear-type clutch (s-IV*) that can be engaged and disengaged.
A design according to the invention for the variable-ratio gear transmission that is even shorter in the directions of the transmission shafts is achieved through providing the idler of the auxiliary gear stage (IV) of the first partial transmission such that the idler engages with a gearwheel, arranged on the intermediate shaft of the first partial transmission, of a gear stage (ZIII) that belongs to the first partial transmission.
In another embodiment of the variable-ratio gear transmission, the two auxiliary gear stages, as well as the gear stage of the first partial transmission having the same gear ratio as the assigned auxiliary gear stage, are combined in a bound gear stage, as a result of which the space required in the directions of the transmission shafts is even further reduced.
In another embodiment of the invention, the auxiliary countershaft is used for the space requirements of the gear stages assigned to the gears, so that, in this respect as well, the variable-ratio gear transmission according to the invention can be accommodated in the axial directions in a narrow space.
In the variable-ratio gear transmission according to the invention having bound gear stages, the gear ratios of the latter are realized by maintaining the ratio (a-III):(a-IV) of the shaft-center distances (a-III and a-IV) of the countershaft (
16
and
17
) with respect to the input shaft (
10
) as equal to the ratio of the gear ratios of the auxiliary gear stages (ZIII* and ZIV*).
In the variable-ratio gear transmission according to the invention, through the use of auxiliary gear stages assigned to the partial transmissions, a high quality of shifting is achieved with regard to the double and triple power shifts through engaging the two powershift clutches.
The variable-ratio gear transmission according to the invention can be used for carrying out double shifts between two gears associated with the first partial transmission by virtue of their assigned gear stages through engaging the assigned auxiliary gear stage.
The variable-ratio gear transmission according to the invention can be used for carrying out double shifts between two gears associated with the second partial transmission by virtue of their assigned gear stages through engaging the assigned auxiliary gear stage.
REFERENCES:
patent: 4658663 (1987-04-01), Hiraiwa
patent: 4823628 (1989-04-01), Hiraiwa
patent: 6021684 (2000-02-01), Alfredsson
patent: 0 061 845 (1982-10-01), None
patent: 2 235 503 (1991-03-01), None
Sperber Ralf
Worner Gunter
Daimler-Chrysler AG
Kenyon & Kenyon
Wright Dirk
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