All-wheel drive vehicle

Abstract

The invention relates to an all-wheel drive vehicle, the drive train of which in particular has exactly one electric machine (1) which drives only the front axle of the vehicle in the front-drive mode, the electric machine (1) being connectable to a cardan shaft (39) via a central differential (13) and a central clutch (15), the central clutch (15) has a cardan shaft which can be drivingly connected to a rear wheel (51) of the vehicle by means of a rear axle differential (47) and a half axle (49), the rear axle being disengaged from the drive train when the central clutch (15) is disengaged, and the rear axle being connectable to the drive train when the central clutch (15) is engaged. According to the invention, a rear axle separation clutch (59) is mounted in one of the half shafts (49) of the rear axle.

Description

Technical Field

[0001] The invention relates to an all-wheel drive two-track vehicle according to the preamble of claim 1 . Background Art

[0002] In all-wheel drive vehicles, the all-wheel drive mode can be realized by a total of four electric motors, each of which is assigned to a wheel as a wheel hub motor. In this case, the vehicle does not need a differential. Alternatively, the all-wheel drive mode can also be realized by an electric motor assigned to the front axle and an electric motor assigned to the rear axle, whose outputs act on the wheels via the front axle differential and the rear axle differential. In addition, there are solutions with an electric motor on the front axle and a locking differential and two electric motors on the rear axle that drive the rear wheels respectively. In addition, drive solutions with an internal combustion engine and torque distribution by means of three locking differentials are known in off-road vehicles.

[0003] This all-wheel drive vehicle has a switchable all-wheel drive mode, wherein the powertrain has an electric motor. In the front-wheel drive mode, the output of the electric motor acts only on the front axle of the vehicle. The electric motor can be connected to a cardan shaft via a central differential and a central clutch, and the cardan shaft can be connected to the rear wheels of the vehicle via a rear axle differential and a half shaft. When the central clutch is disengaged, the rear axle is disconnected from the powertrain, and when the central clutch is engaged, the rear axle can be connected to the powertrain.

[0004] In off-road vehicles with electric drive and two or more motors, there is the following problem: Although multiple motors can independently control torque and speed well without mechanical connection between the front and rear axles, this means that each motor must meet the torque and power requirements of one or more connected wheels. Because one wheel or axle cannot provide torque during off-road operation, the corresponding other drives must provide all the drive power. This leads to high requirements for each motor. In this case, the total power of all motors usually exceeds the requirements of the entire vehicle. In addition, there is a risk of overloading three motors during off-road operation, so the torque and power are reduced. In addition, each motor must have its own control unit (plus inverter). Therefore, multi-motor drives are very expensive and heavy.

[0005] A vehicle drive train with an internal combustion engine drive is known from US Pat. No. 5,373,912 A, which drives a central differential to distribute power to the front and rear axle differentials. A four-wheel drive vehicle with an internal combustion engine is known from DE 103 04806 A1, which drives a central differential via a transmission. A four-wheel drive vehicle with a central differential is known from EP 248 582 B1, which drives the front and rear axle differentials via a cardan shaft to drive the wheels. Summary of the invention

[0006] The object of the present invention is to provide an all-wheel drive dual-track vehicle having improved functionality compared to the prior art, in particular being able to efficiently drive in front-wheel drive mode and / or switch to an all-wheel drive mode during driving under load.

[0007] This object is achieved by the features of claim 1. Preferred developments of the invention are disclosed in the dependent claims.

[0008] The invention proposes an all-wheel drive vehicle with a switchable all-wheel drive mode. The vehicle's drive train preferably has exactly one electric motor, which drives only the front axle of the vehicle in front-wheel drive mode. The electric motor can be connected to the cardan shaft via a central differential or an inter-axle differential and via a central clutch. The cardan shaft is drive-connected to the rear wheels of the vehicle via a rear axle differential and a half shaft. When the central clutch is disengaged, the rear axle is disengaged from the drive train. When the central clutch is engaged, the rear axle can be connected to the drive train. According to the characterizing part of claim 1, a rear axle disconnect clutch is installed on one of the half shafts of the rear axle. In front-wheel drive mode, that is, when the central clutch is disengaged, the rear axle disconnect clutch is disengaged. In this way, the subsystem between the central clutch and the rear axle differential stops running, that is, in particular the cardan shaft and the differential case of the rear axle differential stop running. The compensation gear of the rear axle differential rotates without load.

[0009] In a preferred embodiment, the invention proposes a single motor drive with a total of three differentials and five clutches. With this arrangement, the vehicle can be driven efficiently in front-wheel drive mode, wherein the cardan shaft and the rear bevel gear transmission are completely disengaged. During driving, it is possible to switch to all-wheel drive mode operation fully automatically under load (and switch back). In addition, the drive torque at the wheel can be adjusted by the targeted introduction of differential locks (off-road operation). In contrast, in a vehicle with multiple motors, each motor must meet the requirements (torque and power) of one or more drive wheels. The total power is obtained by adding all installed motors together. This will result in a much higher system power.

[0010] In the solution according to the invention, preferably exactly one electric machine is provided, which is designed to meet the requirements of the entire vehicle. The power requirements in off-road operation are generally lower. This drive concept can permanently distribute the required drive power to the wheels. There is no risk of overheating of the electric machine.

[0011] In front-wheel drive mode, the central locking clutch is engaged and all other clutches are disengaged. The right rear wheel (in the figure) drives the compensation gear of the rear axle differential; but because it is not connected to the left rear wheel, there is no force transmission between the rear bevel gear drive and the rear wheel. Therefore, the differential housing (i.e., differential case), the rear bevel gear drive, the cardan shaft and the clutch rear half of the central clutch do not rotate.

[0012] According to the invention, the drive train is designed in such a way that it can be switched from the front-wheel drive mode to the all-wheel drive mode without interruption of traction during driving operation. When switching from the front-wheel drive mode to the all-wheel drive mode, the rear axle locking clutch is engaged. As a result, the rear bevel gear transmission, the cardan shaft and the clutch rear half of the central clutch are accelerated to a rotation speed related to the driving speed. At this time, the rear axle separation clutch is then disengaged, and then the central clutch is engaged (this is only a possibility, and the switching sequence can be changed arbitrarily). The rear axle locking clutch is preferably implemented as a diaphragm clutch because it must provide a synchronization function. The central clutch and the rear axle separation clutch are dog clutches because they are switched without load and at a minimum differential speed. At this time, no force-locking connection with the rear axle is established.

[0013] In order to be able to subsequently compensate for the speed difference between the front axle and the rear axle, the central locking clutch is disengaged. This process must take place under load in certain situations. Therefore, the central locking clutch is preferably designed as a multi-plate clutch. A dog clutch is also possible, but results in reduced comfort.

[0014] In the road all-wheel drive mode, it is meaningful to engage the central locking clutch and the rear axle locking clutch, which are preferably designed as multi-plate clutches, in a slip-controlled manner. However, the central clutch and the rear axle separating clutch remain permanently engaged, and the front axle locking clutch remains permanently disengaged.

[0015] When the drive torque is very low, the switch from all-wheel drive mode to front-wheel drive mode is performed. The front axle lock clutch and the rear axle lock clutch are disengaged, while the central lock clutch is engaged; the central clutch and the rear axle release clutch are then disengaged.

[0016] The off-road all-wheel drive mode starts from the on-road all-wheel drive mode. No front-wheel drive mode is provided for off-road operation. In order to variably apply the drive torque to the desired wheels, the front axle locking clutch, the central locking clutch and the rear axle locking clutch are fully or partially engaged. It is expedient here that the central locking clutch and the rear axle locking clutch are preferably designed as diaphragm clutches for the reasons mentioned above, thereby enabling regulated off-road operation.

[0017] The front axle lockup clutch is preferably designed as a dog clutch for the following reasons: On the one hand, the front axle lockup clutch is only engaged in extreme driving situations. In this case, comfort plays only a secondary role. Many off-road vehicles do not have a clutch at all. On the other hand, unlike the central lockup clutch and the rear axle lockup clutch, the front axle lockup clutch does not have a dual function.

[0018] The main features are emphasized again in detail below: In a technical embodiment, the rear axle differential can be locked by a rear axle locking clutch. The rear axle locking clutch is preferably implemented as a multi-plate clutch that can be switched under load. When the locking clutch is activated, the differential carrier of the rear axle differential is connected to one of the half shafts, i.e. the rear axle differential is locked.

[0019] As described above, in front-wheel drive mode, the central clutch is disengaged. In order to switch from front-wheel drive mode to all-wheel drive mode with rear-axle engagement, the central clutch is engaged. The central clutch can preferably be a tooth clutch that cannot be switched under load. Against this background, the two clutch halves of the central clutch must operate approximately synchronously in order to achieve load-free switching. For this purpose, the rear-axle locking clutch can be used dual-functionally as a synchronization clutch, with the help of which a synchronization process is achieved before the central clutch engages. During the synchronization process, the cardan shaft (in front-wheel drive mode) is accelerated to vehicle speed. In this way, the clutch half of the central clutch connected to the cardan shaft can be synchronized with the clutch half connected to the central differential.

[0020] After the synchronization process is performed, in the further process, the central clutch is engaged and the rear axle separation clutch is engaged in any switching sequence. When the central clutch is engaged and the rear axle separation clutch is engaged, the rear axle locking clutch is disengaged and / or the central locking clutch is disengaged.

[0021] In a specific embodiment, the central differential can have, on its two output sides, an intermediate shaft extending to the rear of the vehicle to a central clutch and a pinion shaft extending to the front axle differential to the front of the vehicle. The pinion shaft extending to the front axle differential can be connected to the front wheels of the front axle via the front axle differential and the half shafts. In addition, the central differential can be locked by a central locking clutch. The central locking clutch can preferably be implemented as a diaphragm clutch that can be switched under load. When the locking function is activated, the differential housing of the central differential can be connected to the drive shaft extending to the front axle differential and the central differential is locked in the all-wheel drive mode.

[0022] The central locking clutch can be used dual-functionally not only as a differential lock. In addition, the central locking clutch can ensure that the drive torque is transmitted from the central differential to the front axle differential in the engaged state, that is, in the front drive mode.

[0023] Preferably, the motor is directly or indirectly connected to the central differential. In this case, the motor drives a gear wheel constructed on the differential case of the central differential, for example with a transmission and / or a front transmission stage connected in between.

[0024] Furthermore, the front axle differential can be locked by means of a front axle locking clutch. Unlike the central locking clutch and the rear axle locking clutch, the front axle locking clutch can be implemented as a dog clutch that cannot be switched under load. When the locking function is activated, the differential carrier of the front axle differential can be connected to the half shafts, i.e. the front axle differential is locked.

[0025] By means of the drive train according to the invention, the vehicle can be efficiently operated in front-wheel drive mode, while the cardan shaft and, if necessary, the bevel gear drive connected between the cardan shaft and the rear axle differential are completely disconnected from the drive train. The front-wheel drive mode can be switched to the all-wheel drive mode fully automatically during driving and under load. The same also applies to the switch from the all-wheel drive mode to the front-wheel drive mode. In addition, the drive torque at the wheel can be adjusted by the targeted use of three differential locks. Therefore, the motor drive device according to the present invention has a total of three differentials, namely, the front axle differential, the rear axle differential and the central differential, and a total of five clutches, namely, the rear axle separation clutch, the rear axle locking clutch, the central clutch, the central locking clutch and the front axle locking clutch.

[0026] The front-wheel drive mode can be activated in the vehicle's efficiency mode. In contrast, the all-wheel drive mode can be divided into on-road operation and off-road operation, that is, off-road driving or on-road driving.

[0027] In road operation, the rear axle locking clutch designed as a multi-plate clutch and / or the central locking clutch designed as a multi-plate clutch can be disengaged and engaged in a slip-controlled manner to adjust the driving dynamics. In road operation, the central clutch and the rear axle disconnect clutch are permanently engaged, while the front axle locking clutch is disengaged.

[0028] Off-road operation can be the same as highway operation, except that the front axle locking clutch is engaged. Here, before starting off-road driving (that is, under no-load state), the driver can engage the front axle locking clutch (preferably a tooth clutch that cannot be switched under load). BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The following is an explanation of the embodiments of the present invention with reference to the accompanying drawings.

[0030] Figure 1 A schematic diagram shows a powertrain of a two-track motor vehicle having a longitudinally mounted electric machine;

[0031] Figure 2 Based on Figure 1The view of FIG. 1 shows a power train with a transversely mounted electric machine. DETAILED DESCRIPTION

[0032] exist Figure 1 , a powertrain in a dual-track vehicle is shown. Therefore, the powertrain has an electric motor 1 as a power device, which is installed in the longitudinal direction of the vehicle. A transmission 3 and a spur gear stage 5 are connected downstream of the electric motor 1, for example, for torque conversion. The spur gear stage 5 includes a gear 7 constructed on the transmission output shaft of the transmission 16 and a gear 9 on the input side of the differential case 11 of the central differential 13. The central differential 13 has an intermediate shaft 17 extending to the rear of the vehicle to the central clutch 15 and a pinion shaft 21 extending to the front of the vehicle to the front axle differential 19 on its two output sides. According to Figure 1 The pinion shaft 21 extending toward the front of the vehicle is transmission-connected to the ring gear 25 of the differential case of the front axle differential 19 through a bevel gear transmission mechanism 23 .

[0033] The two shafts 17 , 21 mesh with their shaft bevel gears 29 in the differential case 11 of the central differential 13 with a compensating gear 31 rotatably mounted on the differential case 11 .

[0034] exist Figure 1 In the embodiment, the front axle differential 19 is constructed in a substantially similar structure to the center differential 13. Therefore, the half shafts 33 extend from the output side of the front axle differential 19 to the front wheels 35 in both sides in the vehicle transverse direction.

[0035] exist Figure 1 In the embodiment, the intermediate shaft 17 extending to the rear of the vehicle can be connected to the cardan shaft 39 through the central clutch 15 realized as a tooth clutch, and the cardan shaft is output through the bevel gear transmission mechanism 41 and acts on the ring gear 43 on the input side of the differential case 45 of the rear axle differential 47. The structure of the rear axle differential 47 is basically the same as that of the central differential 13. The two output sides of the rear axle differential 47 are connected to the rear wheels 51 through the half shafts 49.

[0036] In addition to the central clutch 15 already mentioned, the drive train has four further clutches, which are described below. Thus, the front axle differential 19 can be locked by means of a front axle locking clutch 53. The front axle locking clutch 53 is designed as a dog clutch that cannot be switched under load. When the locking function is activated, the differential case 27 of the front axle differential 19 is connected to the left half shaft 33, i.e., a front axle differential lock is formed. Similarly, the center differential 13 can also be locked by means of a central locking clutch 55. The central locking clutch 55 is designed as a diaphragm clutch that can be switched under load. When the locking function is activated, the central locking clutch 55 connects the differential case 11 of the center differential 13 to the pinion shaft 21 extending to the front of the vehicle. Similarly, the rear axle differential 47 can also be locked by means of a rear axle locking clutch 57. The rear axle locking clutch 57 is also designed as a dog clutch that cannot be switched under load. When the locking function is activated, the rear axle locking clutch 57 connects the differential case 27 of the front axle differential 19 with the right half shaft 49, that is, a rear axle differential lock is formed. In addition, a rear axle separating clutch 59 is installed on the left half shaft 49.

[0037] exist Figure 1 In the embodiment of the present invention, the front axle differential 19, the bevel gear transmission 23, the front axle locking clutch 53, the central locking clutch 55, the central differential 13, the central clutch 15, the spur gear stage 5 and the transmission 3 are compactly combined in a common transmission housing to form a front axle transmission unit 10. The actuation of the clutches 53, 55, 15 and possibly the transmission 3 can be performed centrally by a shifting system (not shown). Similarly, at the rear axle, the rear axle differential 47, the rear axle separating clutch 49, the rear axle locking clutch 57 and the bevel gear transmission 41 are combined to form a rear axle transmission unit 50.

[0038] The vehicle can be operated in the following operating mode: namely, the front drive mode is activated in the energy-saving efficiency mode of the vehicle. In the front drive mode of the vehicle, only the central locking clutch 55 is engaged, while all other clutches are disengaged. The driving torque generated in this way by the electric machine 1 is guided to the pinion shaft 21 of the front axle differential 19 via the transmission 16, the spur gear stage 5, and the differential case 11 of the central differential 13. Due to the disengaged central clutch 15 and the disengaged rear axle separation clutch 59, in the front drive mode, the subsystem between the central clutch 15 and the rear axle differential 47 stops running, that is, in particular, the cardan shaft 39, the bevel gear mechanism 41 and the differential case 45 of the rear axle differential 47 stop running, and the compensation gear in the rear axle differential 47 rotates without load.

[0039] The center locking clutch 55 thus serves a dual function in the front-wheel drive mode, on the one hand for torque transmission, and on the other hand as a differential lock during the all-wheel drive mode.

[0040] The process of switching from the front-wheel drive mode to the rear-axle engaged all-wheel drive mode is as follows: First, the rear-axle locking clutch 57 is engaged. In this way, a synchronization process is achieved, in which the cardan shaft 39 is accelerated to a rotational speed that is related to the vehicle speed. As a result, the rotational speed of the clutch half of the central clutch 15 connected to the cardan shaft 39 is synchronized with the clutch half connected to the drive shaft 17. After the synchronization process is completed, in the further process, the central clutch 15 is engaged in any switching sequence and the rear-axle disconnect clutch 59 is engaged. With the central clutch 15 engaged and the rear-axle disconnect clutch 59 engaged, the rear-axle locking clutch 57 is disengaged. In order to be able to subsequently compensate for the speed difference between the front axle and the rear axle, the central locking clutch 55 is also disengaged, because this process is carried out under load in some cases, so the central locking clutch 55 is realized as a diaphragm clutch. The realization of the central locking clutch 55 as a dog clutch would result in a loss of comfort.

[0041] The all-wheel drive mode can be divided into on-road operation and off-road operation. In on-road operation, the rear axle locking clutch 57 and the central locking clutch 55 can be disengaged and engaged in a slip-controlled manner to adjust the driving dynamics, while the central clutch 15 and the rear axle disconnect clutch 59 are permanently engaged and the front axle locking clutch 53 is permanently disengaged.

[0042] Off-road operation is designed to be the same as road operation, except that the front axle lock clutch 53 is engaged without load before starting the off-road operation. The front axle lock clutch 53 only needs to be in an engaged state under extreme driving conditions in the off-road operation.

[0043] Thus, an off-road function can be provided by means of the three locking clutches 53 , 55 , 57 , in which all differentials 13 , 19 and 47 can be bridged.

[0044] In contrast, no differential lock is required in highway operation. In this case, it is advantageous from the perspective of driving dynamics that the central locking clutch 55 and the rear axle locking clutch 57 are separated and / or engaged in a slip-controlled manner, so that the torque transmission can be adjusted to a lesser extent.

[0045] The switch from the all-wheel drive mode to the front-wheel drive mode is performed as follows: first, the central locking clutch 55 is engaged to enable the transmission of torque from the electric machine 1 to the front axle while bridging the central differential 13. Then, the central clutch 15 and the rear axle disconnect clutch 59 are disengaged to deactivate the subsystem between the central clutch 15 and the rear axle differential 47.

[0046] exist Figure 2 Another embodiment of the powertrain in a dual-track vehicle is shown in FIG. The structure and function of the powertrain are similar to those of FIG. Figure 1The construction and function of the powertrain shown in are basically the same. Figure 1 The point is that in Figure 2 The central motor 1 and the front axle transmission unit 10 are not installed in the longitudinal direction, but in the transverse direction of the vehicle. Another bevel gear transmission mechanism 61 is connected between the central clutch 15 and the universal shaft 39. In addition, unlike Figure 1 The drive shaft 21 extending to the front axle is not output through a bevel gear transmission mechanism, but is output through a spur gear stage 61 to act on the front axle differential 19.

[0047] Reference numerals list

[0048] 1 Motor

[0049] 3 Transmission

[0050] 5 spur gear stages

[0051] 7.9 Gear

[0052] 10 Transmission housing

[0053] 11 Differential case

[0054] 13 Center differential

[0055] 15 Central Clutch

[0056] 17 Intermediate shaft

[0057] 19 Front axle differential

[0058] 21 Pinion shaft

[0059] 23 Bevel gear transmission mechanism

[0060] 25 Ring gear of the front axle differential

[0061] 27 Differential case for front axle

[0062] 29-axis bevel gear

[0063] 31 Compensation gear

[0064] 33 Front axle half shaft

[0065] 35 front wheel

[0066] 39 Cardan shaft

[0067] 41 Bevel gear transmission mechanism

[0068] 43 Ring gear of rear axle differential

[0069] 45 Differential case

[0070] 47 Rear axle differential

[0071] 49 rear axle half shaft

[0072] 50 Rear axle transmission unit

[0073] 51 rear wheel

[0074] 53 Front axle lock clutch

[0075] 55 Center locking clutch

[0076] 57 Rear axle lock clutch

[0077] 59 Rear axle release clutch

[0078] 60 bevel gear transmission mechanism

[0079] 61 spur gear stages

[0080] FR Driving Direction

Claims

1. An all-wheel drive vehicle, the drive train of which in particular has exactly one electric machine (1) which in front-wheel drive mode drives only the front axle of the vehicle, wherein: The motor (1) can be connected to a cardan shaft (39) via a central differential (13) and a central clutch (15), and the cardan shaft can be connected to the rear wheels (51) of the vehicle via a rear axle differential (47) and a half shaft (49). When the central clutch (15) is disengaged, the rear axle is disconnected from the power transmission system, and when the central clutch (15) is engaged, the rear axle can be connected to the power transmission system. The invention is characterized in that a rear axle separation clutch (59) is installed in one of the half shafts (49) of the rear axle. In the front drive mode, that is, when the central clutch (15) is disengaged, the rear axle separation clutch (59) is disengaged, thereby stopping the subsystem between the central clutch (15) and the rear axle differential (47), that is, in particular, stopping the cardan shaft (39), the bevel gear transmission mechanism (41) and the differential case (45) of the rear axle differential (47).

2. The vehicle according to claim 1, characterized in that The rear axle differential (47) can be locked by means of a rear axle locking clutch (57), in particular a multi-plate clutch which can be switched under load, in particular when the locking function is active, the differential case (45) of the rear axle differential (47) is connected to one of the rear axle half shafts (49) to form a rear axle differential lock.

3. The vehicle according to claim 1 or 2, characterized in that: During driving operation, a switch from the front-wheel drive mode to the all-wheel drive mode can be carried out without interruption of traction. In order to switch from the front-wheel drive mode to the all-wheel drive mode, the central clutch (15), in particular a tooth clutch that cannot be switched under load, can be engaged. In particular, the rear axle locking clutch (57) is used as a synchronizing clutch in a dual function. With the help of this synchronizing clutch, a synchronizing process is carried out before the central clutch (15) is engaged. In this synchronizing process, the cardan shaft (39) is accelerated to a rotational speed related to the vehicle speed, so that the clutch half of the central clutch (15) connected to the cardan shaft (39) can be synchronized to the rotational speed of the clutch half of the central clutch (15) connected to the central differential (13).

4. The vehicle according to claim 3, characterized in that After the synchronization process is carried out in any switching sequence, the central clutch (15) is engaged, the rear axle disconnect clutch (59) is engaged, and in particular, when the central clutch (15) is engaged and the rear axle disconnect clutch (59) is engaged, the rear axle locking clutch (57) is disengaged and / or the central locking clutch (55) is disengaged.

5. A vehicle according to any one of the preceding claims, characterised in that The central differential (13) has an intermediate shaft (17) extending to the rear of the vehicle to the central clutch (15) and a pinion shaft (21) extending to the front of the vehicle to the front axle differential (19) on its output side. In particular, the pinion shaft (21) is drivingly connected to the front wheels (35) of the front axle through the front axle differential (19) and the front axle half shafts (33). In particular, the central differential (13) can be locked by a central locking clutch (55), in particular, a diaphragm clutch that can be switched under load. In particular, when the locking function is in effect, the differential case (11) of the central differential (13) is connected to the drive shaft (21) extending to the front axle differential (19) to form a central differential lock.

6. The vehicle according to claim 5, characterized in that The central locking clutch (55) has a dual function and not only serves as a differential lock, but also ensures the transmission of drive torque from the central differential (13) to the front axle differential (19) in the engaged state, ie in the front drive mode.

7. A vehicle according to any one of the preceding claims, characterised in that The electric motor (1) drives a gear (9) which is constructed on a differential case (11) of a central differential (13) indirectly or directly, in particular with a transmission (3) and / or a preceding transmission stage (5), such as a spur gear stage, connected in between for torque conversion.

8. The vehicle according to claim 5, 6 or 7, characterized in that The front axle differential (19) can be locked by a front axle locking clutch (53), in particular a tooth clutch that cannot be switched under load. When the locking function is activated, the differential case (27) of the front axle differential (19) is connected to the front axle half shaft (33) to form a front axle differential lock.

9. A vehicle according to any one of the preceding claims, characterised in that The front-wheel drive mode is activated in the vehicle's energy-saving efficiency mode, and / or the all-wheel drive mode can be divided into on-road operation and off-road operation.

10. The vehicle according to claim 9, characterized in that In road operation, a rear axle locking clutch (57) designed as a multi-plate clutch and / or a central locking clutch (55) designed as a multi-plate clutch can be disengaged and engaged in a slip-controlled mode for driving dynamics control, while the central clutch (15) and the rear axle separation clutch (59) are permanently engaged and the front axle locking clutch (53) is disengaged, and / or in particular, off-road operation is designed identically to road operation except that the front axle locking clutch (53) is engaged.

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