TRANSMISSION UNIT, TRANSMISSION ARRANGEMENT, AND AGRICULTURAL TOWING VEHICLE

Abstract

A transmission unit for a drivetrain of an agricultural towing vehicle includes a first clutch, a second clutch, a first input shaft, a second input shaft, and an output shaft, wherein the first clutch is connected to the first input shaft and the second clutch is connected to the second input shaft. The transmission includes a plurality of gear sets, wherein a second gear set has the fixed wheel on the first input shaft and the shift wheel on the output shaft, and a third gear set has the fixed wheel on the second input shaft and the shift wheel on the output shaft. The shift wheels of the second and third gear sets can be selectively coupled to a shift element such that at least one winding path gear ratio stage can be formed via the second and the third gear set.

Claims

1.-16. (canceled)

17. A transmission unit fora drivetrain of an agricultural towing vehicle, comprising: a first clutch and a second clutch; a first input shaft, a second input shaft, and an output shaft, wherein the first clutch is connected to the first input shaft and the second clutch is connected to the second input shaft; and a plurality of gear sets, each with a shift wheel and a fixed wheel for establishing a plurality of gear ratio stages, wherein a second gear set of the plurality of gear sets has the fixed wheel on the first input shaft and the shift wheel on the output shaft, and a third gear set of the plurality of gear sets has the fixed wheel on the second input shaft and the shift wheel on the output shaft; wherein the shift wheel of the second gear set and the shift wheel of the third gear set can be selectively coupled to a shift element such that at least one winding path gear ratio stage can be formed via the second and the third gear set.

18. The transmission unit of claim 17, wherein the shift element is movable between a first shift position, in which the shift wheel of the second gear set and the shift wheel of the third gear set are coupled, and a second shift position, in which the shift wheel of the second gear set and the shift wheel of the third gear set are released from one another.

19. The transmission unit of claim 17, wherein the shift wheels are rotatably mounted on the output shaft and the fixed wheels are arranged in a rotationally fixed manner on one of the first input shaft and the second input shaft.

20. The transmission unit of claim 17, further comprising: two coupling elements, wherein each shift wheel is rotationally fixedly and releasably connectable to the output shaft via the two coupling elements.

21. The transmission unit of claim 20, wherein the two coupling elements are each rotationally fixedly and axially displaceably mounted on the output shaft and is axially displaceable via an actuating element.

22. The transmission unit of claim 21, wherein the shift element is arranged between the two coupling elements on the output shaft, and the shift element is in the form of a synchronizer acting on one side and includes a freely rotating sliding sleeve that is axially displaceable on the output shaft and a synchronizing ring arranged axially on one side of the sliding sleeve.

23. The transmission unit of claim 17, wherein a highest gear ratio stage of the plurality of gear ratio stages and a lowest gear ratio stage of the plurality of gear ratio stages are realized as winding path gear ratio stages.

24. The transmission unit of claim 17, wherein a rear-axle bevel gear drive is connected to the output shaft, which is connected to a toothset of a front-axle drive via a front-axle drive wheel, and the output shaft is connected to a parking lock wheel.

25. The transmission unit of claim 17, wherein the pinion of the rear-axle bevel gear drive is integrated in the output shaft.

26. The transmission unit of claim 17, wherein a power take-off drive shaft is arranged in the first and second input shafts.

27. The transmission unit of claim 17, wherein the plurality of gear ratio stages comprises six gear ratio stages and the first and the sixth gear ratio stages are realized as winding path gear ratio stages.

28. The transmission unit of claim 17, further comprising: a clutch drive shaft connecting to a transmission device.

29. The transmission unit of claim 28, wherein the transmission device comprises a range transmission.

30. The transmission unit of claim 29, wherein the range transmission is a multi-stage transmission which can be shifted into a plurality of powershift ratio stages, and the multi-stage transmission comprises a planetary gear set with three integrated planetary stages and a clutch arrangement, wherein the clutch arrangement comprises an additional direct gear such that the multi-stage transmission comprises four gears.

31. The transmission unit of claim 30, wherein the transmission device comprises a powershift reversing unit for reversing the direction of travel.

32. An agricultural towing vehicle comprising the transmission unit of claim 17.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The disclosure as well as further advantages and advantageous developments and refinements of the disclosure, in terms of the hardware as well as the method, will be explained in more detail below by means of exemplary embodiments and with reference to the drawing. Functionally equivalent or comparable components here are provided with the same reference signs. In the schematic drawings:

[0038] FIG. 1 shows a schematic illustration of an agricultural towing vehicle according to the disclosure, and

[0039] FIG. 2 shows a schematic illustration of a first exemplary embodiment of the transmission unit according to the disclosure, and

[0040] FIG. 3 shows a schematic illustration of an engagement sequence diagram of the first exemplary embodiment of the transmission unit according to the disclosure, and

[0041] FIGS. 4a-f each show a schematic illustration of the first exemplary embodiment of the transmission unit according to the disclosure and the power flows of the gear ratio stages A to F of the transmission unit, and

[0042] FIG. 5 shows a schematic illustration of a first exemplary embodiment of the transmission arrangement according to the disclosure, and

[0043] FIG. 6 shows a schematic table of a speed distribution depending on the gear ratio stages of the first exemplary embodiment of the transmission arrangement according to the disclosure, and

[0044] FIG. 7 shows a schematic illustration of a second exemplary embodiment of the transmission unit according to the disclosure, and

[0045] FIG. 8 shows a schematic illustration of a third exemplary embodiment of the transmission unit according to the disclosure, and

[0046] FIG. 9 shows a schematic illustration of a fourth exemplary embodiment of the transmission unit according to the disclosure.

DETAILED DESCRIPTION

[0047] FIG. 1 shows a schematic illustration of an agricultural towing vehicle 10 according to the disclosure, for example in the form of a tractor, with a drivetrain 20 in one possible configuration. The basic structure of an agricultural towing vehicle 10 is assumed to be known to a person skilled in the art. The towing vehicle 10 also comprises a cab 12, a front vehicle axle 14, and a rear vehicle axle 26. The front vehicle axle 14 and the rear vehicle axle 26 are part of the drivetrain 20, with it being possible for the rear vehicle axle 26 generally to be permanently driven and the front vehicle axle 14 generally to be activated on demand.

[0048] The drivetrain 20 also comprises a traction motor 22, which may be in the form of an internal combustion engine, and a transmission structure which may be composed of various individual transmission components, as described below. The transmission structure described in the present case, in terms of the force flow and torque flow and taking the traction motor 22 as a starting point, may have a transmission arrangement 30 according to the disclosure, a traction drive 24 and a rear axle transmission 32. The transmission arrangement 30 comprises a transmission device 40 and a transmission unit 80 according to the disclosure. In this respect, the transmission device 40 is mounted downstream of the traction motor 22. The transmission device 40 is connected in terms of drive to the traction motor 22, and/or can be drivable by the traction motor 22. The transmission unit 80 is mounted downstream of the transmission device 40. In this respect, the transmission unit 80 is connected in terms of drive to the transmission device 40 and/or can be driven by the transmission device 40. The transmission arrangement 30 shown makes it possible to transmit drive power from the traction motor 22 to the output shaft of the transmission unit with different gear ratio stages. The rear vehicle axle 26, which is in drive connection with the output shaft and converts rotation of the front and/or the rear vehicle axle (via ground engagement means connected thereto) into propulsion of the tractor, is therefore driven at a different speed depending on a gear ratio stage selected in the transmission arrangement. Consequently, a tractor equipped with the transmission arrangement, depending on the gear ratio stage selected in the transmission arrangement, can be moved in different speed ranges.

[0049] The towing vehicle 10 may have one or more ground engagement means in the form of wheels 28, which engage with an underlying surface to transmit drive forces and/or by way of which the towing vehicle 10 is supported on the underlying surface. The towing vehicle 10 may moreover have a chassis, it being possible for the chassis for example to be borne by the wheels suspended on the front and the rear vehicle axle 14, 26.

[0050] FIG. 2 shows a schematic illustration, for example a sequence, of a first exemplary embodiment of the transmission unit 80 according to the disclosure. The transmission unit 80 shown in FIG. 2 is a detailed schematic illustration of the transmission unit 80 shown in FIG. 1. Therefore, details not shown in FIG. 1 will be discussed below. The agricultural towing vehicle 10 may comprise the transmission unit 80 as illustrated in FIG. 1.

[0051] The transmission unit 80 comprises a first clutch 82 and a second clutch 84, the input side of which, for example the common input side of which, can be driven. The input side may be connected to, and for example may be drivably connected to or driven by, a drive shaft (reference sign 200, FIG. 5) of the transmission device 40. The transmission unit 80 further comprises a first input shaft 86 and a second input shaft 88 and an output shaft 90, for example one output shaft 90. The output side of the first clutch 82 is connected to the first input shaft 86, for example the first clutch 82 is rotationally fixedly connected to the first input shaft 86. The output side of the second clutch 84 is connected to the second input shaft 88, for example the second clutch 84 is rotationally fixedly connected to the second input shaft 88. The transmission unit 80 comprises a clutch drive shaft 92 as the input side. The first and the second clutch 82, 84 can be moved or shifted between an open state, in which the clutch drive shaft 92 is released in terms of drive from the first and/or the second input shaft 86, 88, and a closed state, in which the clutch drive shaft 92 is in drive connection with the first and/or the second input shaft 86, 88. Furthermore, a rear-axle bevel gear drive 94 is connected to the output shaft 90. In this case, the pinion of the rear-axle bevel gear drive 94 may be in the form of part of the output shaft 90, for example may be integrated in the output shaft 90. The output shaft 90 is moreover also connected to a toothset of a front-axle drive by means of a front-axle drive wheel 96. The front-axle drive wheel 96 is moreover identical to a parking lock wheel 96.

[0052] Moreover, the first and/or the second input shaft 86, 88 are in the form of hollow shafts and the first input shaft 86 is arranged in the second input shaft 88. Furthermore, the first and/or the second input shaft 86, 88 incorporate a power take-off drive shaft 98 for driving a power take-off transmission.

[0053] Four shift wheels 100, 102, 104, 106 are rotatably mounted on the output shaft 90. In total, four fixed wheels 110, 112, 114, 116 are rotationally fixedly arranged on the first and the second input shaft 86, 88, for example are rotationally fixedly connected to the first and the second input shaft 86, 88. In this respect, the first and the second input shaft 86, 88 are respectively assigned two fixed wheels. These each mesh with one of the shift wheels 100, 102, 104, 106 assigned to the output shaft 90. The transmission unit 80 has multiple gear sets, for example four gear sets 120, 122, 124, 126, for establishing gear ratio stages B, C, D, E. To that end, at least one first gear set 120 and one second gear set 122 have the fixed wheel 110, 112, respectively, on the first input shaft 86 and the shift wheel 100, 102, respectively, on the output shaft 90. Moreover, at least one third gear set 124 and one fourth gear set 126 have the fixed wheel 114, 116, respectively, on the second input shaft 88 and the shift wheel 104, 106, respectively, on the output shaft 90. In some embodiments, the first gear set 120 comprises a first fixed wheel 110, which meshes with a first shift wheel 100 on the output shaft 90. The second gear set 122 comprises a second fixed wheel 112, which is in engagement with a second shift wheel 102. The third gear set 124 comprises a third fixed wheel 114, which meshes with a third shift wheel 104. The fourth gear set 126 comprises a fourth fixed wheel 116, which is in engagement with a fourth shift wheel 106.

[0054] The transmission unit 80 also comprises two coupling elements 130, 132, that is to say a first coupling element 130 and a second coupling element 132. The first coupling element 130 is arranged between the first and the second gear set 120, 122 and the second coupling element 132 is arranged between the third and the fourth gear set 124, 126 on the output shaft 90. The shift wheels 100, 102, 104, 106 are rotationally fixedly and releasably connectable to the output shaft 90 by means of the first or the second coupling element 130, 132. In some embodiments, the first shift wheel 100 or the second shift wheel 102 is thus rotationally fixedly and releasably connectable to the output shaft 90 by means of the first coupling element 130. Moreover, the third shift wheel 104 or the fourth shift wheel 106 is rotationally fixedly and releasably connectable to the output shaft 90 by means of the second coupling element 132. Consequently, a respective coupling element 130, 132 is arranged between two respective shift wheels 100, 102, 104, 106, which are arranged on the same input shaft 86, 88, that is to say the first or second input shaft 86, 88. The first and the second coupling element 130, 132 are rotationally fixedly and axially displaceably mounted on the output shaft 90. The first and the second coupling element 130, 132 are in the form of shift assemblies, which comprise actuating devices, for example sliding sleeves and synchronizing rings. As a result, the rotatably mounted shift wheels 100, 102, 104, 106 can be shifted via the coupling elements 130, 132, and therefore a respective fixed speed ratio can be established between the output shaft 90 and the respective first and/or second input shaft 86, 88 depending on a shifting state of the coupling elements 130, 132.

[0055] The transmission unit 80 moreover comprises a shift element 134 for coupling two shift wheels 102, 104. In some embodiments, the second and the third shift wheel 102, 104 can be coupled to the shift element 134. The second and the third shift wheel 102, 104 are rotationally fixedly and releasably connectable to the shift element 134. The second and the third shift wheel 102, 104 can be coupled, for example selectively coupled, to the shift element 134 in such a way that at least one winding path gear ratio stage A, F can be formed via the second and the third gear set 122,124, i.e., for example the first and the second input shaft 86, 88 are thus coupleable to one another. In other words, the shift element 134 may for example be movable between a first shift position, in which the second shift wheel 104 and the third shift wheel 102 are coupled, and a second shift position, in which the second shift wheel 104 and the third shift wheel 102 are released from one another. The shift element 134 is in the form of a synchronizer acting on one side. The shift element 134 is arranged between the first and the second coupling element 130, 132 along the output shaft 90.

[0056] Depending on the shifting state of the first and the second clutch 82, 84 and on the shifting state of the first and the second coupling element 130, 132 and the shift element 134, the transmission unit 80 can be shifted with each of the clutches 82, 84 in two gear ratio stages each, i.e., a total of four gear ratio stages B, C, D, E, and in each case an additional gear ratio stage as a winding path gear ratio stage A, F, i.e., a total of two winding path gear ratio stages A, F, and thus shifted in a total of six gear ratio stages or group gear ratio stages. In this respect, the transmission unit 80 can be shifted under load in that while one clutch, for example the first clutch 82, is being opened, the other clutch, for example the second clutch 84, is closed, with the result that a drive connection existing between the first or the second input shaft 86, 88 and the clutch drive shaft 92 can be replaced by a drive connection to be established via the respective other input shaft 86, 88, without interrupting a drive connection between the first or the second input shaft 86, 88 and the output shaft 90. To preselect a desired gear ratio stage, the shift wheel in question, that is to say for example the first to the fourth shift wheel 100, 102, 104, 106, is rotationally fixedly connected to the output shaft 90 by the respectively assigned first or second coupling element 130, 132, with the result that the gear ratio stages B, C, D, E are realized. If a gear ratio stage A, F as a winding path gear ratio stage is shifted, the second and the third shift wheel 102, 104 are rotationally fixedly connected to one another by the shift element 134, and at the same time the gear ratio stage E or B is activated, that is to say at the same time the first shift wheel 100 is connected to the output shaft 90 by the first coupling element 130 (gear ratio stage E) or the fourth shift wheel 106 is connected to the output shaft 90 by the second coupling element 132 (gear ratio stage B). Consequently, each winding path gear ratio stage runs over three gear sets. The transmission unit 80 thus comprises six gear ratio stages, which for example are powershiftable. In some embodiments, the first and the sixth gear ratio stages A, F are a winding path gear, i.e., realized as winding path gear ratio stages.

[0057] FIG. 3 shows a schematic illustration of an engagement sequence for the first exemplary embodiment of the transmission unit 80 according to the disclosure. The engagement sequence shown in FIG. 3 for the transmission unit comprises the features of the transmission unit 80 shown in FIGS. 1 and 2, and therefore details and/or points of differentiation will be discussed below. According to the engagement sequence indicated in the table, the first gear ratio stage A is shifted via the first clutch 82, via the second coupling element 132 displaced in a direction B, and via the activated shift element 134, that is to say the shift element 134 displaced in a direction W, as a winding path gear ratio stage. The second gear ratio stage B is realized via the second clutch 84 and via the second coupling element 132 displaced in a direction B. The third gear ratio stage C is shifted via the first clutch 82 and via the first coupling element 130 displaced in a direction C. The fourth gear ratio stage D is shifted again via the second clutch 84 and via the second coupling element 132 displaced in a direction D. The fifth gear ratio stage is realized via the first clutch 82 and via the first coupling element 130 displaced in a direction E. The sixth gear ratio stage F is shifted via the second clutch, via the first coupling element 130 displaced in a direction E, and via the shift element 134 displaced in a direction W, as a winding path gear F. In this respect, the displacement of the coupling elements 130, 132 and/or of the shift element 134 is synonymous with an axial displacement of the first or the second coupling element 130, 132 and/or of the shift element 134 and the rotationally fixed connection of the assigned shift wheel 100, 102, 104, 106 to the output shaft 90 by way of the first or the second coupling element 130, 132 and/or the rotationally fixed connection of the second and the third shift wheel 102, 104, while still being rotatably arranged on the output shaft 90.

[0058] FIGS. 4a to 4f show a schematic illustration, for example a sequence, of the first exemplary embodiment of the transmission unit 80 according to the disclosure and the power flows of the gear ratio stages A to F of the transmission unit 80. The transmission unit 80 shown in FIGS. 4a to 4f corresponds substantially to the transmission unit 80 shown in FIGS. 1 to 3, and therefore details and/or points of differentiation will be discussed below.

[0059] FIG. 4a shows the first gear ratio stage A, which is realized as a winding path gear ratio stage via the second, the third and the fourth gear set 122, 124, 126. FIG. 4b shows the second gear ratio stage B, which uses the fourth gear set 126. FIG. 4c shows how the second gear set 122 is utilized to realize the third gear ratio stage C. FIG. 4d shows the fourth gear ratio stage D, in which the third gear set 124 is utilized. FIG. 4e shows the fifth gear ratio stage E, which uses the first gear set 120. FIG. 4f shows the sixth gear ratio stage F, which is realized as a winding path gear ratio stage and utilizes the first to the third gear sets 120, 122, 124. As shown in FIGS. 4a and 4f, the highest gear ratio stage, that is to say the sixth gear ratio stage F, and the lowest gear ratio stage, that is to say the first gear ratio stage A, are realized as winding path gear ratio stages.

[0060] FIG. 5 shows a schematic illustration, for example a sequence, of a first exemplary embodiment of the transmission arrangement 30 according to the disclosure. The transmission arrangement 30 shown in FIG. 5 comprises the transmission unit 80, the transmission unit 80 substantially corresponding to the transmission unit 80 shown in FIGS. 1 to 4f, and therefore details and/or points of differentiation will be discussed below. The transmission arrangement 30 is intended for a drivetrain 20 of an agricultural towing vehicle 10, in order to connect a traction motor 22 to a traction drive 24 of the vehicle 10. The transmission arrangement 30 comprises the transmission unit 80 described and a transmission device 40. The transmission device 40 is mounted upstream of the transmission unit 80. The transmission device 40 comprises a drive shaft 200, which is connected in terms of drive to the input side, for example to the clutch drive shaft 92, of the first and the second clutches 82, 84 of the transmission unit 80.

[0061] The transmission arrangement 30 comprises basically two functional groups, which are in each case in drive connection with one another via shafts. The transmission device 40 is arranged on the input side of the transmission arrangement 30. The transmission device 40 may be in drive connection with the traction motor 22 and be drivable by the traction motor 22. The transmission device 40 is in drive connection with the transmission unit 80 via a drive shaft 200, which is in the form of a hollow shaft. The transmission unit 80 has the output shaft 90, which at the same time is the drive output shaft of the transmission arrangement 30, on the output side.

[0062] The transmission device 40 is in the form of a multi-stage transmission having a plurality of powershift ratio stages, in this instance four powershift ratio stages. The transmission device may for example be powershiftable, for example fully powershiftable. The transmission device 40 has a planetary design. Furthermore, the transmission device 40 may be arranged coaxially with the clutch drive shaft 92 of the transmission unit 80 and/or of a motor drive output shaft 42. The transmission device 80, for example the multi-stage transmission, comprises a planetary gear set 210 with three integrated planetary stages 202. The transmission device 40 moreover also has a clutch arrangement 204 assigned to the planetary stages 202. The planetary gear set 210 further comprises a ring gear 206, driven by the motor drive output shaft 42, and a planet gear carrier 208, which comprises one or more planet gears for each planetary stage 202, for example two, three or four planet gears per planetary stage, which are rotationally fixedly connected to the planet gear carrier 208. Each planetary stage moreover comprises a respective sun gear 212 which in each case is rotationally fixedly connected to a hollow shaft. The respective hollow shaft is connected to a respective clutch unit 214, it being possible for the clutch unit 214 to for example be in the form of a brake. In this respect, the planet gears assigned to a planetary stage may roll on the respectively assigned sun gear 212. Furthermore, the clutch arrangement 204 comprises an additional direct gear between two clutch units, i.e., the clutch units can be coupled by means of a direct clutch 216. In some embodiments, the transmission device 40 in the form of a multi-stage transmission comprises the planetary gear set 210 with three integrated planetary stages 202. The first planetary stage may comprise a first sun gear, which is connected, for example is rotationally fixedly connected, to a first planet shaft. The first planet shaft in turn is connected to the first clutch unit. The second planetary stage may comprise a second sun gear, which is connected, for example is rotationally fixedly connected, to a second planet shaft. The second planet shaft in turn is connected to the second clutch unit. The third planetary stage may comprise a third sun gear, which is connected, for example is rotationally fixedly connected, to a third planet shaft. The third planet shaft in turn is connected to the third clutch unit. Furthermore, the second and the third clutch units may be coupleable by means of the direct clutch 216. Furthermore, the transmission arrangement 30, for example the transmission device 40, may comprise a powershift reversing unit 220 for reversing the direction of travel. In that case, the powershift reversing unit 220 is mounted upstream of the transmission unit 80 and downstream of the multi-stage transmission. The planet gear carrier 208 is connected, for example rotationally fixedly connected, to the powershift reversing unit 220 by means of a shaft, the shaft being drivable by and/or in drive connection with the planet gear carrier 208.

[0063] FIG. 6 shows a table of a speed distribution depending on the gear ratio stages of the first exemplary embodiment of the transmission arrangement 30 according to the disclosure. FIG. 6 relates to the transmission unit 80 or transmission arrangement 30 shown in FIGS. 1 to 5, and therefore the points of differentiation will be discussed below. The table shows the individual gear ratio stages of the transmission arrangement 30. The gear ratio stages or group gear ratio stages A, B, C, D, E, F of the transmission unit 80 are each supplemented by the gear ratio stages or powershift ratio stages 1, 2, 3, 4 of the transmission device 40 per group gear ratio stage, resulting in total in 24 gear ratio stages for the transmission arrangement 30. The advantageous optimum and broad distribution of the speed of the towing vehicle between approximately 2 km/h and approximately 65 km/h is shown.

[0064] FIG. 7 shows a schematic illustration, for example a sequence, of a second exemplary embodiment of the transmission unit 80 according to the disclosure. The transmission unit 80 shown in FIG. 7 corresponds substantially to the transmission unit 80 shown in FIGS. 1 to 6, and therefore details and/or points of differentiation will be discussed below. In contrast to the first exemplary embodiment, three shift wheels, i.e., the second, third and fourth shift wheels 102, 104, 106, are rotatably mounted on the output shaft 90. Instead of the first shift wheel 100 according to the first exemplary embodiment of the transmission unit 80, a first fixed wheel 330 is rotationally fixedly arranged on the output shaft 90, for example rotationally fixedly connected to the output shaft 90. In addition, instead of the first fixed wheel 110 on the first input shaft 86, a first shift wheel 310 is rotatably mounted on the first input shaft 86. The first shift wheel 310 and the first fixed wheel 330 are in engagement with one another. The transmission unit 80 has four gear sets 320, 122, 124, 126 for setting up gear ratio stages B, C, D, E, the main difference from the first exemplary embodiment being the arrangement of the first shift wheel 310 on the first input shaft 86 and of the first fixed wheel 330 on the output shaft 90, i.e., in the first gear set 320. The transmission unit 80 comprises a third coupling element 300. The third coupling element 300 is arranged between the first and the second gear sets 320, 122 on the first input shaft 86. The first shift wheel 310 is rotationally fixedly and releasably connectable to the first input shaft 86 by means of the third coupling element 300. The first coupling element 130 is arranged between the first and the second gear sets 320, 122 and the second coupling element 132 is arranged between the third and the fourth gear sets 124, 126 on the output shaft 90. The third coupling element 300 is rotationally fixedly and axially displaceably mounted on the first input shaft 86. The third coupling element 300 is designed as a shift assembly which comprises an actuating device, for example a sliding sleeve, and one or more synchronizing rings. As a result, the rotatably mounted first shift wheel 310 can be shifted via the third coupling element 300 such that a fixed speed ratio can be established between the first input shaft 86 and the output shaft 90 depending on a shifting state of the third coupling element 300. The first and the third coupling elements 130, 300 are designed as shift assemblies which are shiftable on one side, the synchronizing rings being arranged on one side, i.e., on the right or left, for example therefore on the right or left in the axial direction, of the actuating device or sliding sleeve.

[0065] Depending on the shifting state of the first and the second clutch 82, 84 and on the shifting state of the first, the second and the third coupling element 130, 132, 320 and of the shift element 134, the transmission unit 80 can be shifted with each of the clutches 82, 84 in two gear ratio stages each, i.e., a total of four gear ratio stages B, C, D, E, and in each case an additional gear ratio stage can be shifted as a winding path gear ratio stage A, F, i.e., a total of two winding path gear ratio stages A, F, and thus in a total of six gear ratio stages or group gear ratio stages. The transmission unit 80 can be shifted here under load. The first and the sixth gear ratio stages A, F are in turn implemented as a winding path gear, i.e., as winding path gear ratio stages.

[0066] FIG. 8 shows a schematic illustration, for example a sequence, of a third exemplary embodiment of the transmission unit 80 according to the disclosure. The transmission unit 80 shown in FIG. 8 corresponds substantially to the transmission unit 80 shown in FIGS. 1 to 7, and therefore details and/or points of differentiation will be discussed below.

[0067] In contrast to the first exemplary embodiment, three shift wheels, for example the first, second and third shift wheels 100, 102, 104, are rotatably mounted on the output shaft 90. Instead of the fourth shift wheel 106, a fourth fixed wheel 430 is rotationally fixedly arranged on the output shaft 90, for example rotationally fixedly connected to the output shaft 90. In addition, a fourth shift wheel 410 instead of the fourth fixed wheel is rotatably mounted on the second input shaft 88. The fourth shift wheel 410 and the fourth fixed wheel 430 are in engagement with one another. The transmission unit 80 has four gear sets 120, 122, 124, 420 for establishing gear ratio stages B, C, D, E. In contrast to the first and second exemplary embodiment, a fourth gear set 420 therefore has the fourth shift wheel 410 on the second input shaft 88 and the fourth fixed wheel 430 on the output shaft 90. The transmission unit 80 has a fourth coupling element 400 instead of a third coupling element 300. The fourth coupling element 400 is arranged between the third and the fourth gear sets 124, 420 on the second input shaft 88. The fourth shift wheel 410 is rotationally fixedly and releasably connectable to the second input shaft 88 by means of the fourth coupling element 400.

[0068] The fourth coupling element 400 is rotationally fixedly and axially displaceably mounted on the second input shaft 88. The fourth coupling element 400 is designed as a shift assembly which comprises an actuating device, for example a sliding sleeve, and one or more synchronizing rings. As a result, the rotatably mounted fourth shift wheel 410 can be shifted via the fourth coupling element 400 such that a fixed speed ratio can be established between the second input shaft 88 and the output shaft 90 depending on a shifting state of the fourth coupling element 400. The second and the fourth coupling elements 132, 400 are designed as shift assemblies which are shiftable on one side, on the second input shaft 88 and on the output shaft 90, the synchronizing rings being arranged on one side, i.e., on the right or left, for example therefore on the right or left in the axial direction, of the actuating device or sliding sleeve.

[0069] Depending on the shifting state of the first and the second clutch 82, 84 and on the shifting state of the first, the second and the fourth coupling elements 130, 132, 420 and of the shift element 134, the transmission unit 80 can be shifted with each of the clutches 82, 84 in two gear ratio stages each, i.e., a total of four gear ratio stages B, C, D, E, and in each case an additional gear ratio stage can be shifted as a winding path gear ratio stage A, F, i.e., a total of two winding path gear ratio stages A, F, and thus in a total of six gear ratio stages or group gear ratio stages. The transmission unit 80 can be shifted here under load. The first and the sixth gear ratio stages A, F are in turn implemented as a winding path gear, i.e., as winding path gear ratio stages.

[0070] FIG. 9 shows a schematic illustration, for example a sequence, of a fourth exemplary embodiment of the transmission unit 80 according to the disclosure. The transmission unit 80 shown in FIG. 9 corresponds substantially to the transmission unit 80 shown in FIGS. 1 to 8, for which reason details and/or points of differentiation will be discussed below. The fourth exemplary embodiment is a combination of the second and third exemplary embodiments.

[0071] Two shift wheels, the second and the third fixed wheels 102, 104, are rotatably mounted on the output shaft 90. In addition, two fixed wheels, the first and the fourth fixed wheels 330, 430, are rotationally fixedly arranged on the output shaft 90, for example rotationally fixedly connected to the output shaft 90. The second fixed wheel 112 is rotationally fixedly arranged on the first input shaft 86, for example rotationally fixedly connected to the first input shaft 86. The third fixed wheel 114 is rotationally fixedly arranged on the second input shaft 88, for example rotationally fixedly connected to the second input shaft 88.

[0072] In addition, the first shift wheel 310 is rotatably mounted on the first input shaft 86 and the fourth shift wheel 410 is rotatably arranged on the second input shaft 88. The transmission unit 80 has the third coupling element 300 and the fourth coupling element 400. The third coupling element 300 is thus arranged on the first input shaft 86 and the first coupling element 130 is arranged on the output shaft 90 between the first and the second gear sets 320, 122. The fourth coupling element 400 is thus arranged between the third and the fourth gear sets 124, 420 on the second input shaft 88 and the second coupling element 132 is arranged on the output shaft 90.

[0073] Depending on the shifting state of the first and the second clutch 82, 84 and on the shifting state of the first, the second, the third and the fourth coupling elements 130, 132, 320, 420 and of the shift element 134, the transmission unit 80 can be shifted with each of the clutches 82, 84 in two gear ratio stages each, i.e., a total of four gear ratio stages B, C, D, E, and in each case an additional gear ratio stage can be shifted as winding path gear ratio stages A, F, i.e., a total of two winding path gear ratio stages A, F, and thus in a total of six gear ratio stages or group gear ratio stages. The transmission unit 80 can be shifted here under load. The first and the sixth gear ratio stages A, F are in turn realized as a winding path gear, i.e., as winding path gear ratio stages.