Dual clutch transmission

Abstract

The invention relates to a dual clutch transmission (1) having an input shaft (2), two clutches (3.1, 3.2) for respectively rotationally fixed connection of the input shaft (2) to a respective sub-transmission input shaft (4, 5), two intermediate shafts (6, 8) each having a driven gear wheel (7, 9) arranged coaxially therewith, a first, second and third forward gear wheel (15, 17, 18) respectively arranged coaxially with one of the intermediate shafts (6, 8), and a fourth and fifth forward gear wheel (20, 23) respectively arranged coaxially with the other one of the intermediate shafts (8, 6). It is provided that one of the driven gear wheels (7, 9) is designed as a larger driven gear wheel (7) having a larger diameter and / or a larger number of teeth than the other, smaller driven gear wheel (9), and that the first forward gear wheel (20) is used to form a second gear, the second forward gear wheel (17) is used to form a third gear, and so on, wherein these gears have decreasing transmission ratios in the order mentioned. The dual clutch transmission (1) can form a hybrid transmission (27) together with an electric machine (28).

Description

Technical Field

[0001] This invention relates to a dual-clutch transmission. It also relates to a hybrid transmission having such a dual-clutch transmission and a vehicle drive system having such a dual-clutch transmission or hybrid transmission. Background Technology

[0002] Dual-clutch transmissions are generally disclosed in the prior art, and are therefore disclosed, for example, by DE 10 2018 222009A1. For further details, DE 10 2018 130 621 A1 and DE 11 2009 000016B4 constitute the same type of prior art. The structure herein is such that the input shaft of the dual-clutch transmission is engageable with two sub-transmission input shafts, each of which drives a driven gear via an intermediate shaft, and subsequently, for example, drives a common differential via the driven gear. These intermediate shafts are equipped with driven gears for selecting their respective gears, and the two driven gears on the intermediate shafts are designed as fixed gears, wherein one driven gear is designed as a larger driven gear, having a larger diameter and / or a larger number of teeth than the other smaller driven gear.

[0003] Furthermore, DE 10 2012 001 948 A1 and DE 10 2011 000 152 A1 respectively illustrate dual-clutch transmissions with two intermediate shafts, one of which has a driven gear rotatably connected thereto, and the other intermediate shaft has a switchable driven gear. DE 102011 000 152A1 of the same type also illustrates a switchable driven gear arranged on the hub of the aforementioned switchable driven gear and used to form a reverse gear. In both cases, the dual-clutch transmission is designed to form multiple gears (speed ratio stages), resulting in a structure with a large axial dimension.

[0004] In addition, DE 10 2013 010 723 A1 shows a dual-clutch transmission with two intermediate shafts, wherein one intermediate shaft has a smaller driven gear anti-rotationally connected thereto, while the other intermediate shaft has a larger driven gear that can be switched, wherein the intermediate shaft with the smaller driven gear has a parking lock gear anti-rotationally connected thereto.

[0005] Two more compact wheel sets for hybrid dual-clutch transmissions compared to DE 10 2012 001 948 A1 and DE 10 2011 000 152 A1 have been disclosed by JP 2009 156305A and DE 10 2018 220721A1. Summary of the Invention

[0006] The task of this invention is now to further improve this type of structure and make it more compact and flexible in use.

[0007] According to the present invention, this task is accomplished by a dual-clutch transmission, a hybrid transmission, and a vehicle drive system having the following characteristics.

[0008] Therefore, the dual-clutch transmission based on this design specifies a larger first driven gear and a smaller second driven gear, wherein the larger driven gear has a larger diameter and / or a larger number of teeth than the other driven gear. The forward gears for second, third, and fourth gears are mounted on an intermediate shaft with the smaller driven gear, thus the second, third, and fourth gears are respectively driven by the smaller second driven gear; while the forward gears for fifth and sixth gears are mounted on an intermediate shaft with the larger first driven gear, thus the fifth and sixth gears are respectively driven by the larger first driven gear. The two driven gears then mesh with the driven shaft or a gear and / or differential gear fixed thereon in a manner known per se.

[0009] Therefore, a very simple and compact structure can be achieved, wherein the gears have a decreasing transmission ratio in the order described above.

[0010] According to the invention, one of the driven gears, namely the larger first driven gear, is designed as a driving gear, which is rotatably connected to its corresponding intermediate shaft via a shifting element. The other driven gear in this case is a fixed gear rotatably connected to its intermediate shaft. Here, the reverse gear is rotatably mounted on the hub of the larger driven gear.

[0011] In this invention, an anti-rotation connection refers to the connection of two rotatably mounted components, wherein these components are arranged coaxially with each other and connected to each other such that they rotate at the same angular velocity.

[0012] The dual-clutch transmission according to the invention has the advantage that it can be constructed very compactly and implemented at low cost while maintaining full functionality and service life.

[0013] According to a highly advantageous improvement of the dual-clutch transmission of the invention, it can now also be specified that the larger driven gear is mounted on an intermediate shaft having a fourth and a fifth forward gear, while the other smaller driven gear is mounted on another intermediate shaft having a first, a second, and a third forward gear.

[0014] Another design feature of the dual-clutch transmission of the present invention specifies that a reverse gear is mounted on an intermediate shaft having a larger driven gear. The reverse gear can, according to a highly advantageous improvement, engage only with the forward gear for the second gear, i.e., the first forward gear, so that the reverse gear can be switched accordingly as needed. Preferably, the reverse gear is rotatably mounted on the hub of the larger driven gear according to a highly advantageous design.

[0015] A corresponding and advantageous design here specifies a shift mechanism that selectively connects a larger driven gear, designed as a driving gear, to its intermediate shaft, or connects a reverse driving gear to a larger driven gear, which is then disengaged from its intermediate shaft. Thus, for this purpose, a shift mechanism for engaging the second gear and the shift mechanism for selectively engaging the larger driven gear, designed as a driving gear, to its intermediate shaft or the reverse driving gear can be used to achieve at least one reverse gear in a dual-clutch transmission.

[0016] Another advantageous design of the dual-clutch transmission according to the invention is that a parking lock gear is provided on the intermediate shaft having the smaller driven gear therein. Therefore, the dual-clutch transmission can be correspondingly locked while the vehicle equipped with it is parked.

[0017] Besides its simple and compact structure and the highly flexible controllability of the dual-clutch transmission of the present invention, it is now also well-suited for electrification. The hybrid transmission with such a dual-clutch transmission according to the present invention is correspondingly provided with an electric motor. The internal combustion engine can be connected at least indirectly to the input shaft of the dual-clutch transmission via a disengaged clutch. This indirect connection refers to a connection that can be made through other components. Typical components between the crankshaft of the internal combustion engine and the input shaft of the dual-clutch transmission are, for example, torsional vibration dampers and / or shock absorbers, i.e., components for attenuating or damping torsional vibrations. They can be designed in various different forms in ways known per se, such as having centrifugal pendulums, elastic plates, etc.

[0018] In a highly advantageous design of the hybrid transmission according to the invention, the motor can be connected directly or via transmission components to the input shaft of the dual-clutch transmission. The motor can, for example, be arranged coaxially and directly drive the input shaft of the dual-clutch transmission, with the motor rotor forming part of the shaft. Alternatively, it can be arranged such that its axis of rotation is also parallel to the input shaft of the dual-clutch transmission or the crankshaft of the internal combustion engine, and acts on the input shaft, for example, via transmission components such as gear pairs, belt drives, chains, etc. Another possible arrangement is a perpendicular shaft arrangement, in which case a differential can be used as the transmission element. This is conceivable in principle, but in practice, a parallel or coaxial shaft arrangement is preferred.

[0019] In another alternative to the hybrid transmission according to the invention, it can now be specified that the motor is connected to one of the sub-transmission shafts in an anti-rotational manner. Thus, the motor drives the sub-transmission input shaft of the dual-clutch transmission, or is driven by it when it operates as a generator.

[0020] Another alternative is to connect the motor to a drive gear on one of the intermediate shafts. In particular, one of the forward drive gears, such as the fourth forward drive gear, can be used to connect to the motor, which then meshes with the corresponding drive gear via a fixed gear on the rotor shaft. Thus, the motor can be used as needed, not only as a motor driven, but also as a generator in regenerative or internal combustion engine mode, depending on the shifting mechanism of the forward drive gear.

[0021] It also claims protection for a vehicle drive system. A vehicle drive system having a first axle, a second axle, and a dual-clutch transmission according to the invention, or optionally a hybrid transmission according to the invention, specifies an internal combustion engine engaged or engageable with the dual-clutch transmission, wherein it, and the dual-clutch transmission or hybrid transmission, are configured to form a drive connection with the first driven axle of the vehicle as needed, wherein the second driven axle of the vehicle is purely electric driven by at least one electric motor.

[0022] Therefore, this structure can be designed not only with a pure dual-clutch transmission, but also with a hybrid transmission that includes it to drive one axle while the other axle is driven purely electrically. This now offers many possibilities, such as driving two axles, preferably one driven by an internal combustion engine and the other purely electrically. However, other driving strategies can also be implemented for the vehicle using the structure of the vehicle drive system of the present invention. Thus, for example, by combining an internal combustion engine with a hybrid transmission, a motor acting as a generator can be driven in one of the aforementioned drive unit designs, which then generates current to drive at least one motor on the other axle. Thus, tandem hybrid drive functionality is achieved by means of a correspondingly driven axle, i.e., the second axle. Furthermore, it is possible to achieve parallel hybrid operation on the first axle using a hybrid transmission, while, for example, the second axle is only used for regeneration, or the motor arranged there is completely disregarded in the parallel hybrid drive. Another possible approach exists when using a non-electrified dual-clutch transmission. Thus, it is possible for the first axle to be driven solely by an internal combustion engine and, in parallel or alternatively, for the vehicle to be driven purely electrically by the second axle. Attached Figure Description

[0023] Other advantageous designs of the dual-clutch transmission, the hybrid transmission, and / or vehicle drive system of the present invention also derive from the embodiments detailed below with reference to the figures shown herein:

[0024] Figure 1 The first possible structure of the dual-clutch transmission of the present invention is shown in the form of a wheel assembly diagram.

[0025] Figure 2 An alternative structure of the dual-clutch transmission of the present invention is shown in the form of a wheel assembly diagram.

[0026] Figure 3 An alternative structure of the dual-clutch transmission of the present invention is shown in the form of a wheel assembly diagram.

[0027] Figure 4 Showing Figure 1 The structure is used as an example of a possible variation for electrifying the dual-clutch transmission of the present invention.

[0028] Figure 5 Shown again according to Figure 1 This design serves as another variation of electrifying a dual-clutch transmission.

[0029] Figure 6 It also shows that, according to Figure 1 The design of the dual-clutch transmission serves as another possible alternative for the electrification of dual-clutch transmissions. Detailed Implementation

[0030] exist Figure 1 The dual-clutch transmission 1 can be seen in the diagram, which is presented as a so-called wheel assembly schematic. The dual-clutch transmission 1 has an input shaft, indicated by 2, which can be disengaged or anti-rotationally engaged to an internal combustion engine, an electric motor, and / or other drive assembly.

[0031] In the power transmission direction, the dual clutch 3, consisting of a first clutch 3.1 and a second clutch 3.2, follows the input shaft 2. The first sub-transmission input shaft 4 is connected to the input shaft 2 in a rotationally inert manner via the first clutch 3.1, and the second sub-transmission input shaft 5, coaxially arranged with it, can be connected to the input shaft 2 of the dual-clutch transmission 1 via the second clutch 3.2. Generally, the sub-transmission input shafts 4 and 5 are connected alternately, so that the main power is transmitted through one or the other of the sub-transmission input shafts 4 and 5. In the embodiment shown here, the first sub-transmission input shaft 4 is designed as a solid shaft, and the second sub-transmission input shaft 5, coaxially arranged with it, is designed as a hollow shaft.

[0032] The dual-clutch transmission 1 also has two intermediate shafts. The first intermediate shaft 6 has a first driven gear 7 arranged coaxially therewith, and the second intermediate shaft 8 has a second driven gear 9 arranged coaxially therewith. The two driven gears 7 and 9 then drive the axle of the vehicle equipped with the dual-clutch transmission 1 via a gear (not shown here) on the output shaft of the dual-clutch transmission 1 or via a differential, for example.

[0033] The first sub-transmission input shaft 4 is equipped with two coaxially mounted fixed gears 10 and 11. The second sub-transmission input shaft 5, designed as a hollow shaft, is also equipped with two coaxially arranged fixed gears, designated 12 and 13. A parking lock gear 14 is also mounted on the second intermediate shaft 8, but this should be understood as optional. Furthermore, three forward gears are provided on the second intermediate shaft 8. The first forward drive gear 15 follows the second driven gear 9, which is anti-rotatably connected to it, in the axial direction of the second intermediate shaft 8 and meshes with the fixed gear 13 on the second sub-transmission input shaft 5. Following in the axial direction of the second intermediate shaft 8 is a shift member 16, which anti-rotatably connects the first forward drive gear 15 to the second intermediate shaft 8. Following in the axial direction of the second intermediate shaft 8 is another forward drive gear 17, namely the second forward drive gear. The second forward drive gear 17 meshes with the fixed gear 12 mounted on the second sub-transmission input shaft 5 and can also be anti-rotatably connected to the second intermediate shaft 8 via the shift member 16. Therefore, the shifter 16 controls essentially three gears. It is like... Figure 1 The gear is in neutral as shown in the diagram. If the shifter is pushed out to the right, it connects the first forward gear 15 to the second intermediate shaft 8; if it is pushed out to the left, the shifter 16 connects the second forward gear 17 to the second intermediate shaft 8.

[0034] Along the axial direction of the second intermediate shaft 8, parallel to the second forward gear 17, is the third forward gear 18, which meshes with the fixed gear 11 of the first sub-transmission input shaft 4. Here, a shift member 19 is also subsequently located adjacent to it in this axial direction, through which the third forward gear 18 can be correspondingly connected to the second intermediate shaft 8 in an anti-rotational manner as needed. Thus, the already described selective parking lock gear 14 is positioned as far to the left as possible in the axial direction of the intermediate shaft 8.

[0035] The first intermediate shaft 6 is now described from left to right according to the arrangement of its wheels and shifters. It begins here with the fourth forward gear 20, which meshes with the fixed gear 10 on the first sub-transmission input shaft 4. A shifter 21 allows for anti-rotational connection of the fourth forward gear 20 to the first intermediate shaft 6. Next, axially from left to right, on the first intermediate shaft 6 is another shifter 22 and a fifth forward gear 23. It meshes with the fixed gear 12 on the second sub-transmission input shaft 5 and can be anti-rotationally connected to the first intermediate shaft 6 via the shifter 22. Adjacent to the right axially is a shifter 24, followed by a reverse gear 25 and a first driven gear 7, also designed as a drive gear on the first intermediate shaft 6. The first driven gear 7 is mounted on the intermediate shaft 6 and can be anti-rotationally connected to it via the shifter 24 as needed. The reverse gear 25 is mounted on the hub of the first driven gear 7 and can be connected to it via the shifter 24. The shift member 24 can therefore selectively connect the first driven gear 7 to the first intermediate shaft 6, or alternatively connect the reverse gear 25 to the first driven gear 7, in which case the first driven gear is not connected to the first intermediate shaft 6. Like all the previously described shift members 16, 19, 21, 22, and 24, this shift member also has the ability to... Figure 1 The neutral position is shown accordingly in the diagram.

[0036] Shown here Figure 1 The reverse gear 25 is not visible in the upper projection of the wheel assembly diagram and is therefore shown with dashed lines: it meshes with the first forward gear 15 and can only be driven on demand through it, because the reverse gear 25 does not mesh with other gears in the dual-clutch transmission 1.

[0037] Besides the fact that "the first driven gear 7 is designed as a moving gear on the first intermediate shaft 6," another feature of the dual-clutch transmission 1 is that the first driven gear 7 is larger than the second driven gear 9, which is usually designed as a fixed gear. Here, "larger than" means that it has a larger diameter and, consequently, a larger number of teeth. In principle, a larger number of teeth alone is sufficient.

[0038] The structure of the dual-clutch transmission 1 thus allows for corresponding shifting of the gears, wherein the first forward drive gear 15 is used to achieve the second gear, the second forward drive gear 17 is used to achieve the third gear, and the third forward drive gear 18 is used to achieve the fourth gear, and then power is output to a differential (not shown here) via the second driven gear 9, respectively. The fifth and sixth gears are correspondingly achieved via the fourth forward drive gear 20 and the fifth forward drive gear 23, for which power is output to the same differential via a first driven gear 7 with a larger diameter, which is anti-rotatably connected to the first intermediate shaft 6. To achieve the reverse gear, the reverse drive gear 25 is correspondingly connected to the first driven gear 7 and driven via the first forward drive gear 15, i.e., the drive gear for the second gear. Here, the first reverse gear can be achieved through the drive path of the first forward drive gear 15 (which is in turn anti-rotatably connected to the second intermediate shaft 8 via the shift member 16), the drive of the reverse drive gear 25, and the driven action via the first driven gear 7 engaged therewith. The second reverse gear can be achieved by simultaneously considering the fourth forward gear 20 and the fifth forward gear 23, i.e., the fifth and sixth gears.

[0039] The first forward gear is also implemented in the dual-clutch transmission with two gears in mind, but instead of engaging the reverse gear 25, the first driven gear 7 is engaged to the first intermediate shaft 6 via the shift member 24. This essentially results in the gear ratio change / difference between the first and second gears corresponding to the gear ratio difference between the fifth and sixth gears.

[0040] exist Figure 2 The diagram shows an alternative structure to the dual-clutch transmission 1, of which only the following describes the following. Figure 1 The difference lies in the structure. Here, the second fixed gear 11 on the first sub-transmission input shaft 4 is now omitted. The first fixed gear 10 therefore meshes not only with the fourth forward gear 20 on the first intermediate shaft 6, but also with the third forward gear 18 on the second intermediate shaft 8, which is therefore arranged relative to the third forward gear 18 and its shift member 19. Figure 1 The structure is arranged in a mirror image on the second intermediate axis 8. In other respects, in Figure 2 The structure of the dual-clutch transmission 1 in the diagram corresponds to Figure 1 The aforementioned structure.

[0041] This also applies to the aforementioned operating mode; therefore, the gear ratio difference from first to second gear here corresponds to the gear ratio difference from fifth to sixth gear. Furthermore, the gear ratio difference from third to fifth gear roughly corresponds to the gear ratio difference from fourth to sixth gear, while the gear ratio difference from second to third gear is now... Figure 2 The structure shown can be freely chosen.

[0042] exist Figure 3 The diagram shows another variation of the dual-clutch transmission 1. Its starting point is also... Figure 1 The diagram of the dual-clutch transmission 1 is provided below, so the differences will only be described in detail here. The difference now lies in the use of a common multi-purpose shifter 26 instead of two separate shifters 21 and 22. This common multi-purpose shifter 26 is designed to function as a shifter with a sliding sleeve. Therefore, without neutral, the fourth forward gear 20 or the fifth forward gear 23, or in the middle position of the sliding sleeve, can selectively connect the two forward gears 20 and 23 to the first intermediate shaft 6. The multi-purpose shifter 26 here switches the forward gears 20 and 23 for the fifth and sixth gears. Other aspects and operating methods correspond to... Figure 1 The aforementioned situation. Clearly, a structure with a shifter 26 to replace shifters 21 and 22 can now be implemented accordingly, and as... Figure 2 The structure shown engages both the fixed gear 10 with the fourth forward gear 20 and the third forward gear 18.

[0043] The dual-clutch transmission 1 is now particularly suitable for electrification in every one of the described variants. Figure 4 The diagram correspondingly shows a hybrid transmission 27, the core of which is indicated by a dual-clutch transmission 1, which is shown here according to... Figure 1 The design is a variation, but without the selectability of parking lock gear 14. According to Figure 2 and Figure 3 Other designs or combinations thereof, as well as the application of the parking lock gear 14, are obviously also feasible here. The key difference now is that the motor 28 supplements the dual-clutch transmission 1 into a hybrid transmission 27, which, in the embodiment shown here, is arranged coaxially with the dual clutch 3 and the input shaft 2 of the dual-clutch transmission 1. The motor 28 is preferably directly connected to the input shaft 2. Furthermore, the input shaft 2 is connected to the crankshaft 30 of the internal combustion engine 31 via a disengagement clutch 29. This connection is generally achieved indirectly, i.e., components for damping and resisting torsional vibrations are provided in the connection region or in the region between the crankshaft 30 and the input shaft 2 of the dual-clutch transmission 1. However, this is known to those skilled in the art, and therefore such components are neither explained in detail nor considered accordingly in the illustration of this figure.

[0044] When clutch 29 is open, the structure can now be purely electric, as the dual-clutch transmission 1 is driven by motor 28, with its driven gears 7, 9 being driven depending on the shift position of the shifting element. When clutch 29 is closed, internal combustion engine 31 and motor 28 can engage in terms of their power, or motor 28 can operate without load or be driven by internal combustion engine 31 as a generator.

[0045] exist Figure 5 and Figure 6 The diagram shows other possible configurations using the electric motor 28. Here, the internal combustion engine 31 and the selective disengagement clutch 29, which is also provided in the drive system, are omitted from the illustration. The dual-clutch transmission 1 structure within its respective hybrid transmission 27 corresponds to, as shown... Figure 1 The structure shown here is merely an example and can also be used... Figure 2 and Figure 3 The structure or combination thereof.

[0046] Motor 28 is now in Figure 5 and Figure 6 In the two embodiments, the axes are arranged parallel to the axes of input shaft 2 or sub-transmission input shafts 4 and 5, respectively. Figure 5 In one embodiment, the rotor shaft 32 of the motor 28 engages with a gear 33, which meshes with a fourth forward gear 20, thus enabling force transmission from the motor 28 to the dual-clutch transmission 1 or from the dual-clutch transmission to the motor 28, allowing the motor to operate as a generator. If the possibility of switching the transmission connection relying on the shift member 21 can be abandoned, then a method such as... Figure 6 The structure shown is similar in other respects, in which gear 33 meshes directly with the first fixed gear 10 on the first sub-transmission input shaft 4, as indicated again by the dashed line.

[0047] The dual-clutch transmission 1, or the hybrid transmission 27 containing it, can now form a vehicle drive system together with the internal combustion engine 31 and / or the electric motor 28 to drive the vehicle, which is not shown here. The axles of the vehicle, not shown here, are preferably driven in different ways. The first axle engages, for example, via a differential (already explained several times, but not shown here) to a first driven gear 7 and a second driven gear 9. The first axle can therefore be driven by the dual-clutch transmission 1 and, for example, the internal combustion engine 31 and / or the electric motor 28, which engage or can engage with it. The second axle is purely electric in this case. Thus, drive via the internal combustion engine alone or via the parallel hybrid drive of the first axle can be achieved. Pure electric operation is possible via the second axle.

[0048] Especially in Figure 5 and Figure 6 When the hybrid transmission 27 is used in the variant, the functionality of a tandem hybrid drive system can also be achieved. The internal combustion engine 31 then drives the motor 28 via the dual-clutch transmission 1. The motor 28 then supplies the electrical power generated in generator mode to an electric motor (not shown) on the second axle of the vehicle, so that the vehicle can be driven purely electrically via the second axle in the tandem hybrid system mode.

Claims

1. A dual-clutch transmission (1), comprising: Input axis (2); Two clutches (3.1, 3.2) are used to connect the input shaft (2) to the corresponding sub-transmission input shafts (4, 5) in an anti-rotational manner; Two intermediate shafts (6, 8) each having a driven gear (7, 9) arranged coaxially with it; The first, second and third forward gears (15, 17, 18) are arranged coaxially with one of the intermediate shafts (6, 8); The fourth and fifth forward gears (20, 23) are arranged coaxially with another of the intermediate shafts (8, 6); in, The first driven gear in the driven gears (7, 9) is designed to be a larger first driven gear (7), which has a larger diameter and / or a larger number of teeth than the smaller second driven gear (9) in the driven gears (7, 9). The first forward gear (15) is used to form the second gear, the second forward gear (17) is used to form the third gear, the third forward gear (18) is used to form the fourth gear, the fourth forward gear (20) is used to form the fifth gear, and the fifth forward gear (23) is used to form the sixth gear, wherein these gears have decreasing transmission ratios in the above order. The larger first driven gear (7) is designed as a moving gear, which is anti-rotatably connected to the corresponding intermediate shaft (6) via a shift member (24), wherein the smaller second driven gear (9) is designed as an anti-rotatably connected to the fixed gear of its intermediate shaft (8). The second, third, and fourth gears are respectively achieved through transmission via the smaller second driven gear (9), and the fifth and sixth gears are respectively achieved through transmission via the larger first driven gear (7). The reverse gear (25) is mounted on the intermediate shaft (6) having the larger first driven gear (7) and rotatably mounted on the hub of the larger first driven gear (7). Its characteristics are, The reverse gear (25) meshes only with the first forward gear (15).

2. The dual-clutch transmission (1) according to claim 1, characterized in that, The larger first driven gear (7) is mounted on a first intermediate shaft (6) having the fourth and fifth forward gears (20, 23), and the smaller second driven gear (9) is mounted on a second intermediate shaft (8) having the first, second and third forward gears (15, 17, 18).

3. The dual-clutch transmission (1) according to claim 2, characterized in that, In the axial direction of the second intermediate shaft (8), the first forward gear (15) follows the second driven gear (9), the second forward gear (17) follows the first forward gear (15), and the third forward gear (18) follows the second forward gear (17).

4. The dual-clutch transmission (1) according to claim 1, characterized in that, A shifting element (24) is provided, which selectively connects the larger first driven gear (7) to its intermediate shaft (6) or connects the reverse gear (25) to the larger first driven gear (7), wherein the larger first driven gear is separated from its intermediate shaft (6).

5. The dual-clutch transmission (1) according to any one of claims 1 to 4, characterized in that, A parking lock gear (14) is provided on the intermediate shaft (8) having the smaller second driven gear (9).

6. A hybrid transmission (27) having a dual-clutch transmission and an electric motor (28) according to any one of claims 1 to 5.

7. The hybrid transmission (27) according to claim 6, characterized in that, The motor (28) is directly or via at least one transmission element engaged or combustible to the input shaft (2) of the dual-clutch transmission (1).

8. The hybrid transmission (27) according to claim 6, characterized in that, The motor (28) engages with a moving gear (7, 15, 17, 18, 20, 23, 25) on one of the intermediate shafts (6, 8).

9. The hybrid transmission (27) according to claim 6, characterized in that, The motor (28) is engaged or can be engaged to one of the sub-gearbox input shafts (4, 5).

10. A vehicle drive system having an internal combustion engine (32) and two driven axles, namely a first axle and a second axle, wherein, The first axle is driven by the internal combustion engine (32) via a dual-clutch transmission (1) according to any one of claims 1 to 5 or a hybrid transmission (27) according to any one of claims 6 to 9, wherein the second axle is designed to be an axle capable of being driven purely electrically.

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