Dual clutch transmission

This application is a National Stage completion of PCT/EP2008/063426 filed Oct. 8, 2008, which claims priority from German patent application serial no. 10 2007 049 262.8 filed Oct. 15, 2007.

The present invention relates to a dual clutch transmission for a motor vehicle.

Known from the publication DE 103 05 241 A1 is a 6-speed or 7-speed dual clutch transmission. The dual clutch transmission comprises two clutches, each connected with their inputs to the drive shaft and with their output to one of the two transmission input shafts. The two transmission input shafts are coaxially positioned towards each other. In addition, two countershafts are positioned parallel to the transmission input shafts, their idler gear wheels mesh with the fixed gear wheels of the transmission input shafts. Furthermore, coupling devices are axially movable and rotationally fixed to the countershaft to shift the respective gear wheels. Each selected ratio is transferred by the drive gear wheels to a differential transmission. To achieve the desired gear ratio steps in this known dual clutch transmission, a vast number of gear planes are required, so that a significant amount of installation space is needed.

In addition, a spur gear change speed transmission is known from the publication DE 38 22 330 A1. The spur gear change speed transmission comprises a dual clutch, switchable under power, where one part is connected with a drive shaft and the other part with a hollow drive shaft, rotatably supported on the drive shaft. For certain gear ratios, the drive shaft can be coupled with the hollow drive shaft via a shifting device.

Known from the publication DE 10 2004 001 961 A1 is a power transmission with two clutches, which are each assigned to a partial transmission. The transmission input shafts of the two partial transmissions are coaxially arranged to each other and mesh, via fixed gear wheels, with idler gear wheels of the designated countershaft. The respective idler gear wheels of the countershafts can be connected in a rotationally fixed manner, with the respective countershaft via designated shifting devices. The particular idle wheels of the countershaft can be connected via the assigned shifting devices with the associated countershaft. A 7-gear transmission in a rotationally fixed manner is known through this publication in which an additional shift element is provided to connect the two transmissions input shafts to establish an additional transmission stage. The 7-gear transmission requires in this embodiment at least six gear planes in the two partial transmissions, to achieve the transmission ratio stages. This causes an unwanted extension of the construction length in axial direction, it is therefore significantly limiting the use in a motor vehicle.

It is the task of the present invention to propose a dual clutch transmission based on the previously described type, in which power engaging gear ratio steps can be realized, possibly cost-efficient and with just a few component parts, which need little installation space.

Thus, a dual clutch transmission with two clutches, optimized for needed installation space, is proposed, in which the inputs are connected with a drive shaft and the outputs are each connected with one of two transmission input shafts that are coaxial to each other. The dual clutch transmission comprises at least two countershafts, on which gear wheels, designed as idler gear wheels, are rotatably positioned, and on the two transmissions input shafts are gear wheels connected in a rotationally fixed manner as fixed gear wheels, which at least partially mesh with the idler gear wheels. In addition, several coupling devices are provided for connection of an idler gear wheel with a countershaft in a rotationally fixed manner. The dual clutch transmission, in accordance with the invention, has one output gear wheel each, or constant pinion at the two countershafts, which each are coupled with gears of a drive shaft, to connect the respective countershaft with the output, and has at least an actuating, or lockable shifting device as a so-called winding-path gear shifting device for a rotationally fixed connection of two gear wheels, whereby several power engaging forward gears and at least one reverse gear are implemented.

In accordance with the invention, the dual clutch transmission can comprise preferably just four gear planes for instance, two dual gear planes are provided, and, in each dual gear plane, an idler gear wheel is each assigned, on the first and the second countershaft, assigned to a fixed gear wheel of the transmission input shafts, whereby in each dual-gear plane at least one idler gear wheel can be used for at least two gears, and two single gear planes are provided, in which one idler gear wheel of the countershaft is assigned to a fixed gear wheel of one of the transmission input shafts, so that at least one winding-path gear is engaging via a first shifting device and at least one winding-path gear is engaging via an additional shifting device. Due to the possible multi-use of idler gear wheels, the proposed dual clutch transmission enables a maximum number of gear ratios with as few gear planes as possible, and preferably all forward gears and all reverse gears are power engaging at sequential execution.

Through the use of two single gear planes, instead of a dual gear plane, the inventive dual clutch transmission can achieve harmonious, progressive gear shifting, especially in the fourth, fifth, sixth, and seventh gear. In addition, a maximum of four shifting devices are used for each of shaft, which can be realized via shifting devices and/or coupling devices, with the need for, if necessary, a maximum of two actuation devices at each countershaft.

The inventive and presented dual clutch transmission can preferably be designed as a 7-gear transmission. Due to the short construction method, as compared to known transmission configurations, the inventive dual clutch transmission is especially applicable in a front-transverse construction method. However, other construction methods are also possible, and depend on the design and the available construction of the respective motor vehicle.

It can be provided, within the framework of the invention, that via a first shifting device on the second countershaft, an idler gear wheel of the second partial transmission can be connected with an idler gear wheel of the first partial transmission, whereby via the first shifting device at least a first forward gear, the seventh forward gear, and a reverse gear are each shiftable as a winding-path gear. Hence, the first forward gear and the seventh forward gear can be realized as winding-path gears through the gear wheels of the third forward gear and the fourth forward gear.

The inventive dual clutch transmission enables that, via one shifting device, winding-path gears can be realized in which the gear wheels of both partial transmissions are coupled, to enable hereby the flow of force via both partial transmissions. The respective, applied shifting device serves hereby for the coupling of two idler gear wheels and brings hereby the transmission input shafts into a dependency.

The positioning of the shifting devices to connect two defined idler gear wheels, independently of each embodiment of the dual clutch transmission, can vary, so that the shifting devices do not have to be necessarily positioned between the idler gear wheels which have to be connected. Thus, other positioning designs of each shifting device are conceivable, for instance to optimize the connection to an actuating device.

It can be provided, in accordance with a possible embodiment of the dual clutch transmission, that the first gear plane, designed as dual gear plane, comprises a fixed gear wheel on the second transmission input shaft of the second partial transmission, and that the second gear plane, designed as dual gear plane, as well as the third and fourth gear planes, designed as single gear planes, comprise three fixed gear wheels on the first transmission input shaft of the first partial transmission. However, it is also possible that the first gear plane, designed as a dual gear plane, comprises a fixed gear wheel on the second transmission input shaft of the second partial transmission, and that the second, and the third gear plane, designed as single gear planes, and the fourth gear plane, designed as a dual gear plane, three fixed gear wheels on the first transmission input shaft of the first partial transmission. Hereby, and independent from the respective embodiment variation, each of the four fixed gear wheels of the transmission input shafts can be used for at least two gears. In an advantageous design, only three idler gear wheels on a countershaft are required for the forward gear ratios, which mesh with fixed gear wheels of the transmission input shaft, and only two idler gear wheels are required on the other countershaft, which also mesh with fixed gear wheels of the transmission input shafts.

For the realization of reverse gears for this inventive dual clutch transmission, an intermediate gear wheel can be applied, and positioned on an intermediate shaft. It is also possible that one of the idler gear wheels of a countershaft serves for at least one reverse gear position. Thus, an additional intermediate shaft is not needed for the reverse gear transmission, because one of the idle wheels mashes with a fixed gear wheel, and an additional idle wheel of the other countershaft. Therefore the intermediate gear, required for the reverse gear, is positioned to engage an idler gear wheel on a countershaft and it also serves for the realization of at least one additional forward gear. The intermediate gear can always be designed as step gear, independent of whether it is positioned on the countershaft or on an additional intermediate shaft.

To obtain the desired transmission ratio steps, this inventive dual clutch transmission provides that on each countershaft at least one dual action coupling device is installed. The provided coupling devices, either in the activated or engaged condition, dependent on the direction of activation, can each connect an assigned idler gear wheel to the countershaft in a rotationally fixed manner. Also, a single action coupling device can be positioned on least one of the countershafts. Clutches, which are operating for instance as hydraulic, electric, pneumatic, mechanically operated clutches, or interlocking claw couplings can be utilized as coupling devices, as well as any kind of synchronization device which serves as the rotationally fixed connection of an idler gear wheel of a countershaft. It is possible to replace a dual action coupling device with two single action coupling devices and vice versa.

It is possible that the mentioned options for positioning of the gear wheels vary, and also the number of gear wheels and the number of coupling devices are altered to realize additional power engaging and non-power engaging gears, for further reduction of installation space and part cost reduction for this inventive dual clutch transmission. Especially fixed gear wheels of dual gear planes can be split into two fixed gear wheels for two single gear planes. Hereby, the shifting can be improved. It is also possible, to swap the countershafts. The partial transmissions can also be swapped, meaning mirror imaging around a vertical axle. Hereby, the hollow shaft and the solid shaft are swapped. It is possible hereby to position the smallest gear wheel on the solid shaft, to further optimize the use of the available installation space. In addition, neighboring gear planes can be swapped, to optimize, for example, a deflection of the shaft and/or to optimize connecting of a shifting actuator device. Also, the respective mounting position of the coupling devices on the gear plane can be varied. In addition, the direction of action of the coupling devices can be varied.

The gear numbering used in here is freely defined. It is also possible to add a crawler gear, to improve the off road characteristics or the acceleration performance for a motor vehicle. In addition, the first gear can be left out, for instance, to better optimize the entirety of the gear steps. The numbering of the gears varies through these measures accordingly.

Independently of the respective variations of the embodiments of the dual clutch transmission, the drive shaft and the output shaft can be positioned non-coaxial to each other, which enables an especially space saving configuration. For instance, the shafts which are positioned spatial one after another, can also be slightly offset to each other. In that configuration, a direct gear with the transmission ratio one can be realized by teeth meshing and can be shifted, relatively free, to the fourth, fifth, for sixth gear. A different configuration option of the drive shaft and the output shaft is also possible.

Preferably, the proposed dual clutch transmission is equipped with an integrated output stage. The output stage can comprise a fixed gear wheel as an output gear at the output shaft, which is meshes with a first output gear wheel, as a fixed gear wheel of the first countershaft, as well as with a second output gear wheel, as a fixed gear wheel of the second countershaft. However, it is possible that at least one of the output gear wheels is designed as a meshing gear wheel.

Advantageously, the lower forward gears and the reverse gears can be activated through a starting, or shifting clutch to focus higher loads on this clutch and to construct the second clutch with less need for installation space and as more cost-effective. Especially, the gear planes in the proposed dual clutch transmission can be positioned in a way that one can start, by way of the inner transmission input shaft or the outer transmission input shaft, always starting via the more appropriate clutch, which is also possible in a concentrically positioned, radially nested construction of the dual clutch. The gear planes can be positioned as mirror-symmetric, or swapped, respectively. It is also possible that the countershafts are swapped or positioned in a mirror imaging way.

Independent of the respective embodiments, the provided gear planes of the dual clutch transmission can be swapped. It is also possible, to use instead of a dual gear plane two single gear planes and/or vice versa. In addition, the two partial transmissions can be positioned as mirrored.

Following, the present invention is further explained based on the drawings.

It shows:

FIG. 1 a schematic view of a first embodiment variation of an inventive 7-gear dual clutch transmission;

FIG. 2 a shift scheme of the first embodiment variation in accordance with FIG. 1 ;

FIG. 3 a schematic view of a second embodiment variation of the inventive 7-gear dual clutch transmission;

FIG. 4 a shift scheme of the second embodiment variation in accordance with FIG. 3 ;

FIG. 5 a schematic view of a third embodiment variation of the inventive 7-gear dual clutch transmission;

FIG. 6 a shift scheme of the third embodiment variation in accordance with FIG. 5 .

In each of the FIGS. 1 , 3 , and 5 , possible embodiments of the 7-gear dual clutch transmission are shown. The respective shift schemes of the embodiments are presented in FIGS. 2 , 4 , and 6 as tables.

The 7-gear dual clutch transmission comprises two clutches K 1 and K 2 , in which the input sides are connected to a drive shaft w_an, and the output sides are each connected with one of the two, coaxially positioned towards each other, transmission input shafts w_K 1 , w_K 2 . Also a torsion vibration damper 14 can be positioned at the drive shaft w_an. In addition two countershafts w_v 1 , w_v 2 are provided, on which gear wheels are rotatably supported and are designed as idler gear wheels 5 , 6 , 7 , 8 , 9 , 10 . On the two transmission input shafts w_K 1 , w_K 2 , gear wheels are rotatably positioned and designed as fixed gear wheels 1 , 2 , 3 , 4 , which at least partially mesh with the idler gear wheels 5 , 6 , 7 , 8 , 9 , 10 .

To connect the idler gear wheels 5 , 6 , 7 , 8 , 9 , 10 with the respective countershaft w_v 1 , w_v 2 , several coupling devices A, B, C, D, E, F, which can be activated or engaged are provided with the countershaft w_v 1 , w_v 2 . In addition, drive gear wheels 12 , 13 are positioned on the two countershafts w_v 1 , w_v 2 , designed as constant pinion, which each are coupled with gears of an output drive shaft w_ab.

Beside the coupling devices A, B, C, D, E, F, which provide a rotationally fixed connection between a gear wheel and the respective countershaft w_v 1 , w_v 2 , at least one winding-path gear shifting device K is provided in the dual clutch transmission to provide a rotationally fixed connection of two gear wheels of a countershaft w_v 1 , w_v 2 , to realize at least one winding-path gear.

In the first and third embodiments, the shifting device K is positioned between the first gear plane, designed as dual gear plane 5 - 8 , and the second gear plane, designed as dual gear plane 6 - 9 , and is positioned on the second countershaft w_v 2 , to connect the idler gear wheel 8 with the idler gear wheel 9 . In a second embodiment variation, the shifting device K of the first gear plane, designed as dual gear plane 5 - 8 and the third gear plane, designed as single gear plane 3 - 9 , is positioned on the second countershaft w_v 2 , to also connect the idler gear wheel 8 with the idler gear wheel 9 .

Thus, and in accordance with the invention, the double clutch transmission has only four gear planes, whereby in each embodiment two dual gear planes 5 - 8 , 6 - 9 ; 5 - 8 , 7 - 10 are provided, and whereby two single gear planes 6 - 2 , 3 - 9 ; 7 - 3 , 4 - 10 are provided, so that at least one power shiftable winding-path gear can be shifted via a shifting device K. For instance, a claw can be used as shifting devices for K, I or similar, to connect two gear wheels.

In the first and third embodiment variation, in accordance with FIGS. 1 and 5 , the two dual gear planes 5 - 8 , 6 - 9 , form the first and the second gear planes, and the two single gear planes 7 - 3 , 4 - 10 , form the third and fourth gear planes. Whereas in the second embodiment variation, in accordance with FIG. 3 , the two dual gear planes 5 - 8 , 7 - 10 , are formed by the first and fourth gear planes, whereby both single gear planes 6 - 2 , 3 - 9 are formed by the second and third gear planes.

In the first embodiment, in accordance with FIG. 1 , in the first gear plane, designed as dual gear plane 5 - 8 , the fixed gear wheel 1 with the second transmission input shaft w_K 2 , as well as with the idler gear wheel 5 of the first countershaft w_v 1 , and also with the idler gear wheel 8 of the second countershaft w_v 2 . In the second gear plane, designed as dual gear plane 6 - 9 the fixed gear wheel 2 of the first transmission input shaft w_K 1 meshes with the idler gear wheel 6 of the first countershaft w_v 1 as well as with the idler gear wheel 9 of the second countershaft w_v 2 . In the third gear plane, designed as single gear plane 7 - 3 , the fixed gear wheel 3 of the first transmission input shaft w_K 1 meshes with the idler gear wheel 7 of the first countershaft w_v 1 . Finally, in the fourth gear plane, designed as single gear plane 4 - 10 , the fixed gear wheel 4 of the first transmission input shaft w_K 1 meshes with an intermediate gear ZR, whereby the intermediate gear ZR enables the reversal of rotation to realize a reverse gear R 1 , R 2 , R 3 . The intermediate gear ZR is rotatably positioned on the intermediate shaft w_zw, whereby the intermediate shaft w_zw, is positioned in parallel to the countershafts w_v 1 , w_v 2 . The intermediate gear ZR also meshes with the idler gear wheel 10 of the second countershaft w_v 2 .

The third embodiment, in accordance with FIG. 5 , is only different from the first embodiment by enabling the rotation reversal for the reverse gears, in the third embodiment, in the third gear plane, designed as single gear plane 7 - 3 .

In the second embodiment, in accordance with FIG. 2 , in the first gear plane, designed as a dual gear plane 5 - 8 , the fixed gear wheel 1 of the second transmission input shaft w_K 2 meshes with the idler gear wheel 5 of the a first countershaft w_v 1 , as well as with the idler gear wheel 8 of the second countershaft w_v 2 . In the second gear plane, designed as a single gear plane 6 - 2 , the fixed gear wheel 2 of the first transmission input shaft w_K 1 meshes only with the idler gear wheel 6 of the first countershaft w_v 1 . Finally, in the fourth gear plane, designed as single gear plane 4 - 10 , the fixed gear wheel 4 of the first transmission input shaft w_K 1 meshes with an intermediate gear ZR, whereby the intermediate gear ZR enables the reversal of rotation to realize a reverse gear R 1 , R 2 , R 3 . The intermediate gear ZR is rotatably positioned on an intermediate shaft w_zw, whereby the intermediate shaft w_zw, in this example, is positioned parallel to the countershafts w_v 1 , w_v 2 . The intermediate gear ZR also meshes with the idler gear wheel 10 of the second countershaft w_v 2 .

The third embodiment, in accordance with FIG. 5 , differs from the first embodiment creation shafts by the fact, that the rotation reversal, to realize the reverse gears, are provided in the third embodiment in the third gear plane, designed as single gear plane 7 - 3 .

In the second embodiment variation, in accordance with FIG. 2 , the fixed gear wheel 1 of the second transmission input shaft w_K 2 meshes with the idler gear wheel 5 of the first countershaft w_v 1 , as well as with the idler gear wheel 8 of the second countershaft w_v 2 . In the second gear plane, designed as a single gear plane 6 - 2 , the fixed gear wheel 2 of the first transmission input shaft w_K 1 meshes only with the fixed gear wheel 6 of the first transmission input shaft w_K 1 . In the third gear plane, designed as a single gear plane 3 - 9 , the fixed gear wheel 3 of the first transmission input shaft w_K 1 , meshes with the idler gear wheel 9 of the second countershaft w_v 2 . Finally, in the fourth gear plane, designed as a dual gear plane 7 - 10 , the fixed gear wheel 4 of the first transmission input shaft w_K 1 meshes with the idler gear wheel 7 of the first countershaft w_v 1 , as well as with an intermediate gear ZR. whereby the intermediate gear ZR enables the reversal of rotation for a reverse gear R 1 , R 2 , R 3 . The intermediate gear ZR is rotatably positioned positioned on an intermediate shaft w_zw parallel to the countershafts w_v 1 , w_v 2 . The intermediate gear meshes also with the idler gear wheel 10 of the second countershaft w_v 2 .

On each countershaft w_v 1 , w_v 2 , in this example, a dual action coupling device B, C; E, F is provided whereby on the first countershaft w_v 1 the dual action coupling device B, C is positioned between the second gear plane, designed as a double gear plane 6 - 9 , and the third gear plane, designed as a single gear plane 7 - 3 and that on the second countershaft w_v 2 the dual action coupling device E, F is positioned between the second gear plane, designed as a dual gear plane 6 - 9 and the fourth gear plane, designed as a single gear plane 4 - 10 . For each dual action coupling device B, C; E, F, also two single action coupling devices can be provided. Via the coupling device B, the idler gear wheel 6 can be connected with the first countershaft w_v 1 and via the coupling device C, the idler gear wheel 7 can be connected with the first countershaft w_v 1 . Via the coupling device E, the idler gear wheel 9 can be connected with the a second countershaft w_v 2 , and via the coupling device F, the idler gear wheel 10 can be connected with the second countershaft w_v 2 . The second embodiment, in accordance with FIG. 3 , only differs by the fact, that the dual action coupling device E, F is positioned on the second countershaft w_v 2 , between the third gear plane, designed as a single gear plane 3 - 9 , and the fourth gear plane, designed as a dual gear plane 7 - 10 .

To connect the idler gear wheel 5 with the first countershaft w_v 1 , a single action coupling device A is assigned to the first gear plane, designed as a dual gear plane 5 - 8 . In addition, a single action coupling device D is assigned to the first gear plane, designed as a dual gear plane 5 - 8 , to connect the idler gear wheel 8 with the second countershaft w_v 2 .

In the inventive double clutch transmission, an integrated output stage is provided, having the output gear wheel 12 , which is connected with the first countershaft w_v 1 in a rotationally fixed manner, and having the output gear wheel 13 , which is connected in a rotationally fixed manner with the second countershaft w_v 2 . The output gear wheel 12 and the output gear wheel 13 each mesh with a fixed gear wheel 11 of the output shaft w_ab. However, other shiftable connections are possible between the output gear wheels 12 , 13 and the respectively assigned countershaft w_v 1 , w_v 2 .

FIGS. 2 and 4 present in the respective table an exemplary shift scheme for the first and second embodiments of the 7-gear double clutch transmission, in accordance with FIGS. 1 and 3 .

It can be seen in the shifting schemes, that the first forward gear G 1 can be shifted via the second clutch K 2 and via the activated coupling device C, as well as via the activated shifting device K as a winding-path gear, the second forward gear G 2 can be shifted via the first clutch K 1 and via the activated coupling device C, the third forward gear G 3 can be shifted via the second clutch K 2 and via the activated coupling device D, the fourth gear G 4 can be shifted via the first clutch K 1 and via the activated coupling device E, the fifth forward gear G 5 can be shifted via the second clutch K 2 and via the activated coupling device A, the sixth gear G 6 can be shifted via the first clutch K 1 and via the activated coupling device B and that the seventh forward gear G 7 can be shifted via the first clutch K 1 and via the activated coupling device A, and via the activated shifting device K as a winding-path gear.

It can also be seen in the shifting scheme, that the first reverse gear R 1 can be shifted via the first clutch K 1 and via the activated coupling device F, and that an additional reverse gear R 3 can be shifted via the second clutch K 2 and via the activated coupling device F and via the activated shifting element K as a winding-path gear.

In the first and second embodiments, if a shifting device I is assigned to the first countershaft w_v 1 , to connect the idler gear wheel 5 with the idler gear wheel 6 in a rotationally fixed manner, in an activated or engaged condition of the shifting device I, an additional reverse gear R 2 can be shifted via the second clutch K 2 and via the activated coupling device F as a winding-path gear.

In addition, for the first and the second embodiments of the double clutch transmission, a low speed gear C 1 can be shifted, as a winding-path gear, via the first clutch K 1 , via the activated coupling device A, via the activated coupling device C, and via the activated coupling device D, a disengaged coupling device S_ab 1 and assigned to the output gear wheel 12 , not shown in the schematic views for simplicity reasons in a disengaged condition of the coupling device S_ab 1 , the output gear wheel 12 is disconnected from the assigned first countershaft w_v 1 . In addition, an overdrive gear O 1 can be shifted via the second clutch K 2 , via the activated coupling device A, via the activated coupling device C, and via the activated coupling device E, and the disengaged coupling device S_ab 1 and assigned to the output gear wheel 12 , as a winding-path gear.

From the shifting scheme in accordance with FIG. 2 , or 4 it can be seen that in the first forward gear G 1 , beginning from the second clutch K 2 , the gear steps i_ 3 , i_ 4 , and i_ 2 are used, whereby the two partial transmissions are coupled via the shifting device K. In the second forward gear G 2 , only the gear step i_ 2 is used, in the third forward gear G 3 the gear wheel step i_ 3 is used, in the fourth forward gear G 4 , the gear wheel step i_ 4 is used, in the fifth forward gear G 5 , the gear wheel step i_ 5 is used, and in the sixth forward gear G 6 , the gear wheel step i_ 6 is used. In the seventh forward gear G 7 , the gear steps i_ 4 , i_ 3 , and i_ 5 are used, whereby the two partial transmissions are again coupled via the shifting device K. In the reverse gear R 1 , only the gear step i_R is used, whereby the additional, possible reverse gear R 2 , is winding-path gear, uses the gear wheel steps i_ 5 , i_ 6 , and i_R, to couple the 2 partial transmissions via the additional shifting element I. In another reverse gear R 3 the gear wheel steps i_ 3 , i_ 4 , and i_R, couple the two partial transmissions via the shifting device K. In the low speed gear C 1 , the gear wheel steps i_ 2 , i_ 5 , and i_ 3 are used, where by the possibility for coupling the two partial transmissions is realized through the disengaged coupling device S_ab 1 , which is assigned to the output gear wheel 12 on the first countershaft w_v 1 . For the overdrive gear O 1 , the gear wheel steps i_ 5 , i_ 2 , and i_ 4 are used, whereby the possibility for coupling the two partial transmissions is realized through the disengaged coupling device S_ab 1 , which is assigned to the output gear wheel 12 on the first countershaft w_v 1 .

In the a first embodiment, in accordance with FIG. 1 , the gear wheel step i_ 2 of the second forward gear G 2 , and the gear wheel step i_R of the reverse gears R 1 , R 2 , R 3 are each assigned to a single gear plane 7 - 3 , 4 - 10 , so that the first forward gear G 1 can be better adjusted, and the second forward gear G 2 , as well as the reverse gear R can be freely adjusted. In the second embodiment variation, in accordance with FIG. 3 , the gear wheel step i_ 4 of the a fourth forward gear G 4 , and the gear wheel step i_ 6 of the sixth forward gear G 6 are each assigned to a single gear plane 6 - 2 , 3 - 9 , whereby shifting of the forward gears G 4 to G 7 can be presented progressively.

In the table of FIG. 6 , an example of a shifting scheme for the third embodiment of the 7-gear double clutch transmission, in accordance with FIG. 5 , is shown.

From this shifting scheme it can be seen, that the first forward gear G 1 can be shifted via a second clutch K 2 and via the activated coupling device F, and via the activated, or engaged. Shifting device K, as a winding-path gear, the second forward gear G 2 can be shifted via the first clutch K 1 and via the activated coupling device F, the third forward gear G 3 can be shifted via the second clutch K 2 and via the activated coupling device D, that the fourth forward gear G 4 can be shifted via the first clutch K 1 and via the activated coupling device E, the fifth forward gear G 5 can be shifted via the second clutch K 2 and via the activated coupling device A, the sixth forward gear G 6 can be shifted via the first clutch K 1 and via the activated coupling device B, and the seventh forward gear G 7 can be shifted via the of first clutch K 1 and via the activated coupling device A, and via the activated shifting device K as a winding-path gear. The shifting scheme also presents that a reverse gear R 3 can be shifted via a first clutch K 1 and via the activated coupling device C.

In the third embodiment variation, if an additional coupling device S_ab 1 is provided, which is assigned to the output gear wheel 12 and which disconnects the output gear 12 from the first countershaft w_v 1 in a non-engaged condition, an additional reverse gear R 1 can be shifted via the second clutch K 2 , via the activated coupling device A, via the activated coupling device C, and via the activated coupling device E, as well as a winding-path gear at the non-engaged coupling device S_ab 1 , assigned to the output gear wheel 12 . Also, an additional reverse gear R 2 can be shifted via the second clutch K 2 , via the activated coupling device A, via the activated coupling device C, and via the activated coupling device F, as well as a winding-path gear at disengaged coupling device S_ab 1 , assigned to the output gear wheel 12 .

Furthermore, it is possible in the third embodiment to shift an overdrive gear O 1 and as a winding-path gear, via the second clutch K 2 , via the activated coupling device B, via the activated coupling device D, and via the activated coupling device F, with an additional non-engaged coupling device S_ab 2 which is assigned to the output wheel 13 . If the coupling device S_ab 2 is in a non-engaged condition, the output gear wheel 13 is disconnected from the second countershaft w_v 2 .

The shift scheme, in accordance with FIG. 6 , shows in particular that in the first forward gear G 1 , beginning at the second clutch K 2 , the gear wheel steps i_ 3 , i_ 4 , and i_ 2 are used, whereby the two partial transmissions are coupled via the shifting element K. In the second forward gear G 2 , only the gear wheel step i_ 2 is used, in the third forward gear G 3 the gear wheel step i_ 3 is used, in the fourth forward gear G 4 the gear wheel step i_ 4 is used, in the fifth forward gear G 5 , the gear wheel step i_ 5 is used and in the sixth forward gear G 6 , the gear wheel step i_ 6 is used. In the seventh forward gear G 7 , the gear wheel steps i_ 4 , i_ 3 , and i_ 5 are used, whereby the two partial transmissions are coupled again with each other via the shifting device K. in the reverse gear R 1 , the gear wheel steps i_ 5 , i_R, i_ 4 , and reverse gear R 2 , the gear wheel steps i_ 5 , i_R, i_ 2 are used, whereby both reverse gears R 1 and R 2 are shifted as winding-path gears, whereby the possibility for the coupling of the 2 are sure transmissions is realized through the non-engaged coupling device S_ab 1 , which is assigned to the output gear wheel 12 at the first countershaft w_v 1 . The next possible reverse gear R 3 only uses the gear wheel step i_R. For the overdrive gear, as a winding-path gear, the gear wheel steps i_ 3 , i_ 2 , i_ 6 are used, whereby the possibility for the coupling of the two partial transmissions is realized through the non-engaged coupling device S_ab 2 , which is assigned to the output gear wheel 13 on the second countershaft w_v 2 .

Therefore, in the third embodiment in accordance with FIG. 5 , the gear wheel steps i_ 2 , i_ 3 , and i_ 4 are positioned on the second countershaft w_v 2 , whereby advantages are arising in regard to the hearing design and in regard pull the shaft bearing and the shaft design.

Independent of the respective embodiment, if the low speed gear C 1 and/or the overdrive gear O 1 are not used, a disconnection of the output gear wheel 12 , or 13 respectively, from the countershaft w_v 1 , w_v 2 is not necessary and therefore, the coupling device S_ab 1 or S_ab 2 can be omitted for shifting the forward gear G 1 to G 7 and for the shifting the reverse gears R 1 , R 2 , R 3 . However, when the low speed gear C 1 and/or the overdrive gear O 1 are used, via coupling device S_ab 1 or S_ab 2 so that the coupling device S_ab 1 or S_ab 2 needs to be partially engaged for shifting of the forward gears G 1 to G 7 the reverse gears R 1 , R 2 , R 3 .

Independent of the respective embodiment, both partial transmissions are used in the first forward gear G 1 and in the highest forward gear G 7 and at least in one reverse gear, because they are winding-path gears. The first power shiftable forward gear is also a winding-path gear. In addition the gear wheel steps i_ 3 and i_ 5 of the power shiftable forward gears G 3 and G 5 , are positioned together in the first gear plane, designed as dual gear plane 5 - 8 . Also, the gear wheel steps i_ 2 and i_R are positioned together in the third dual gear plane 7 - 10 , or in two neighboring single gear planes 7 - 3 and 4 - 10 , respectively, in the second and third embodiments.

Summarizing the first embodiment variation, in accordance with FIG. 1 , it can be seen that in the first gear plane, designed as a dual gear plane 5 - 8 , the idler gear wheel 5 is used for four forward gears G 5 , G 7 , C 1 , O 1 and for one reverse gear R 2 , and the idler gear wheel 8 for four forward gears G 1 , G 3 , G 7 , C 1 and for one reverse gear R 3 . In the second gear plane, designed as a dual gear plane 6 - 9 , the idler gear wheel 6 can be used for one forward gear G 6 and for one reverse gear R 2 , and the idler gear wheel 9 for four forward gears G 1 , G 4 , G 7 , O 1 and for one reverse gear R 3 . Also in the third gear plane, designed as a single gear plane 7 - 3 , the idler gear wheel 7 can be used for four forward gears G 1 , G 2 , C 1 , O 1 and for one reverse gear R 3 . Finally in the fourth gear plane, designed as a dual gear plane 7 - 10 , the idler gear wheel 10 can be used for 3 reverse gears R 1 , R 2 , R 3 and the idler gear wheel 7 can be used for four forward gears G 1 , G 2 , C 1 , O 1 .

Summarizing the third embodiment variation, in accordance with FIG. 6 , it can be seen that in the first gear plane, designed as a dual gear plane 5 - 8 , the idler gear wheel 5 can be used for two forward gears G 5 , G 7 and for two reverse gears R 1 , R 2 and the idler gear wheel 8 can be used for four forward gears G 1 , G 3 , G 7 , O 1 . In the second gear plane, designed as dual gear plane 6 - 9 , the idler gear wheel 6 can be used for two forward gears G 6 , O 1 and the idler gear wheel 9 can be used for three forward gears G 1 , G 4 , G 7 and for one reverse gear R 1 . Also, in the third gear plane, designed as a single gear plane 7 - 3 , the idler gear wheel 7 can be used for three reverse gears. Finally in the fourth gear plane, designed as a single gear plane 4 - 10 , the idler gear wheel 10 can be used for three forward gears G 1 , G 2 , O 1 , and for one reverse gear R 2 .

In all embodiments of the double clutch transmission and due to the provided multiple use of certain idler gear wheels, less gear planes are required and therefore less parts, but still having the same amount of gears, is resulting in an advantageous construction space saving and in a cost reduction.

Independent of the respective embodiment variation, with regard to the numeral “1” in the boxes of the respective tables, in accordance with FIGS. 2 and 4 , of the shift schemes means that the associated clutch K 1 , K 2 , or the associated coupling devices A, B, C, D, E, F respectively, or the associated shifting devices K, I are engaged. In contrast, an empty box in the respective table, in accordance with FIGS. 2 and 4 , of the shift schemes means that the associated clutch K 1 , K 2 , or the associated coupling device A, B, C, D, E, F, respectively, or the associated shifting device K, I, respectively, is each disengaged.

Deviating from the previously mentioned rules, it applies for the coupling device S_ab 1 , or S_ab 2 assigned to a drive gear wheel 12 , or 13 , respectively, that the coupling device S_ab 1 or S_ab 2 in case of an empty box in the associated table of the shift schemes, in accordance with FIGS. 2 and 4 , must be disengaged but that, a box having the numeral “1”, depending from the gear in a first group of gears, the coupling device S_ab 1 or S_ab 2 must be engaged, and in a second group of gears, the coupling device S_ab 1 or S_ab 2 can be both disengaged or also engaged. In addition, there is the possibility in many cases to add additional coupling devices or shifting devices, without affecting the flow of force. A gear pre-selection is hereby enabled.