All-wheel drive vehicle

Abstract

The invention relates to a vehicle with all-wheel drive, the drive train of which is provided with exactly one electric machine (1) which drives only the front axle of the vehicle in the front drive mode, wherein the electric machine (1) can be connected to a cardan shaft (39) via a central differential (13) and a central clutch (15), which can be connected to the rear wheels (51) of the vehicle via a rear axle differential (47) and half shafts (49), the rear axle being disconnected 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 disconnect clutch (59) is installed in one of the half shafts (49) of the rear axle.

Description

Technical Field

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

[0002] In all-wheel drive vehicles, all-wheel drive can be achieved using a total of four motors, each acting as a hub motor and assigned to one wheel. In this case, the vehicle does not require a differential. Alternatively, all-wheel drive can also be achieved using motors assigned to the front axle and motors assigned to the rear axle, their outputs acting on the wheels via front and rear axle differentials respectively. Furthermore, there are configurations with a motor and locking differential on the front axle and two motors on the rear axle to drive the rear wheels. Additionally, drive systems with internal combustion engines and torque distribution via three locking differentials are known in off-road vehicles.

[0003] This type of all-wheel-drive vehicle features switchable all-wheel-drive modes, with an electric motor integrated into the powertrain. In front-wheel-drive mode, the motor's output acts only on the front axle. The motor is connected to a universal joint via a central differential and a central clutch, and the universal joint is connected to the rear wheels via a rear axle differential and half-shafts. When the central clutch is disengaged, the rear axle is disconnected from the powertrain; when the central clutch is engaged, the rear axle can be engaged with the powertrain.

[0004] Electric off-road vehicles with two or more motors present the following challenges: While multiple motors can independently control torque and speed well when there is no 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 in off-road operation, if one wheel or axle cannot provide torque, the other drives must provide all the drive power. This places high demands on each motor. In such cases, the total power of all motors often exceeds the requirements of the entire vehicle. Furthermore, there is a risk of overloading all three motors during off-road operation, resulting in reduced torque and power. Additionally, each motor must have its own control unit (plus an inverter). Therefore, multi-motor drives are very expensive and heavy.

[0005] US 5,373,912A discloses a vehicle powertrain with an internal combustion engine drive that drives a central differential to distribute power to the front and rear axle differentials. DE 103,04806A1 discloses an all-wheel-drive vehicle with an internal combustion engine that drives the central differential via a transmission. EP 248,582B1 discloses an all-wheel-drive vehicle with a central differential that drives the front and rear axle differentials via universal joints to drive the wheels. Summary of the Invention

[0006] The purpose of this invention is to provide an all-wheel drive dual-track vehicle with improved functionality compared to the prior art, particularly in that it can drive efficiently in front-wheel drive mode and / or switch to all-wheel drive mode during driving under load.

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

[0008] This invention proposes an all-wheel drive vehicle with switchable all-wheel drive modes. The vehicle's powertrain preferably has exactly one electric motor, which drives only the front axle in front-wheel drive mode. The motor is connected to a universal joint via a central differential or an inter-axle differential and via a central clutch. The universal joint is connected to the rear wheels of the vehicle via a rear axle differential and half-shafts. When the central clutch is disengaged, the rear axle is disengaged from the powertrain. When the central clutch is engaged, the rear axle is connected to the powertrain. According to a characteristic portion of claim 1, a rear axle release clutch is mounted on one of the rear axle half-shafts. In front-wheel drive mode, i.e., when the central clutch is disengaged, the rear axle release clutch is disengaged. In this way, the subsystem between the central clutch and the rear axle differential stops operating, specifically the universal joint and the differential housing of the rear axle differential. The compensating gear of the rear axle differential rotates without load.

[0009] In a preferred embodiment, the present invention proposes a single-motor drive with a total of three differentials and five clutches. With this arrangement, the vehicle can operate efficiently in front-wheel drive mode, where the universal joint and rear bevel gear transmission are completely disengaged. During driving, it can automatically switch to all-wheel drive mode under load (and switch back). Furthermore, the drive torque at the wheels can be adjusted (for off-road operation) by selectively introducing differential locks. In contrast, in vehicles 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 the installed motors together. This results in a much higher system power.

[0010] In the embodiment of the invention, preferably, exactly one motor is provided, designed to meet the requirements of the entire vehicle. Power requirements during off-road operation are typically low. This drive system can consistently distribute the required drive power to each wheel. There is no risk of motor overheating.

[0011] In front-wheel drive mode, the central locking clutch engages, and all other clutches disengage. The right rear wheel (in the diagram) drives the compensating gear of the rear axle differential; however, 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., the differential case), the rear bevel gear drive, the universal joint, and the rear half of the central clutch do not rotate.

[0012] According to the invention, the powertrain is designed to switch from front-wheel drive mode to all-wheel drive mode during vehicle operation without interruption of traction. When switching from front-wheel drive to all-wheel drive mode, the rear axle lock-up clutch engages. This causes the rear bevel gear drive, universal joint, and the rear clutch portion of the central clutch to accelerate to a speed related to the vehicle speed. At this point, the rear axle disengages the clutch, then the rear axle lock-up clutch disengages, and immediately afterwards, the central clutch engages (this is only one possibility; the switching sequence can be arbitrarily changed). The rear axle lock-up clutch is preferably implemented as a diaphragm clutch because it must provide a synchronizing function. The central clutch and the rear axle disengagement clutch are dog clutches because they switch without load and at minimal differential speed. No force-locked connection with the rear axle is established at this time.

[0013] To subsequently compensate for the speed difference between the front and rear axles, the center lock-up clutch disengages. This process must, under certain conditions, be performed under load. Therefore, the center lock-up clutch is preferably implemented as a diaphragm clutch. A jaw clutch is also feasible, but results in reduced comfort.

[0014] In all-wheel drive operation, it is meaningful that the central locking clutch and the rear axle locking clutch, preferably configured as diaphragm clutches, engage in an anti-slip adjustment manner. However, the central clutch and the rear axle disengagement clutch remain permanently engaged, while the front axle locking clutch remains permanently disengaged.

[0015] When the driving torque is very low, the system switches from all-wheel drive mode to front-wheel drive mode. The front and rear axle lock-up clutches disengage, while the center lock-up clutch engages; then the center clutch and rear axle release clutch disengage immediately afterward.

[0016] The off-road all-wheel drive mode originates from the on-road all-wheel drive mode. No front-wheel drive mode is provided for off-road driving. To variably apply driving torque to the desired wheels, the front axle locking clutch, center locking clutch, and rear axle locking clutch are fully or partially engaged. Preferably, for the reasons stated above, the center locking clutch and rear axle locking clutch are diaphragm clutches, thereby enabling regulated off-road operation.

[0017] The front axle lock-up clutch is preferably implemented as a dog clutch for the following reasons: Firstly, the front axle lock-up clutch engages only under extreme driving conditions. In these situations, comfort is secondary. Many off-road vehicles completely eliminate the clutch. Secondly, unlike the center lock-up clutch and the rear axle lock-up clutch, the front axle lock-up clutch does not have a dual function.

[0018] The key feature is reiterated below: In the technical implementation, the rear axle differential can be locked via a rear axle locking clutch. The rear axle locking clutch is preferably implemented as a diaphragm clutch that can switch under load. When the locking clutch is activated, the differential housing of the rear axle differential is connected to one of the half-shafts, thus locking the rear axle differential.

[0019] As described above, in front-wheel drive mode, the central clutch disengages. To switch from front-wheel drive mode to rear-axle-engaged all-wheel drive mode, the central clutch engages. The central clutch is preferably a dog clutch that cannot be switched under load. In this context, the two clutch halves of the central clutch must operate substantially synchronously to achieve no-load switching. For this purpose, the rear axle lock clutch can function as a dual-function synchronizing clutch, by means of which the synchronization process is achieved before the central clutch engages. During synchronization, the universal joint (in front-wheel drive mode) is accelerated to vehicle speed. In this way, the rotational speed of the clutch half of the central clutch connected to the universal joint is synchronized with the rotational speed of the clutch half connected to the central differential.

[0020] Following the synchronization process, in a further process, the central clutch is engaged and the rear axle disengagement clutch is engaged in any switching sequence. While the central clutch is engaged and the rear axle disengagement clutch is engaged, the rear axle locking clutch disengages and / or the central locking clutch disengages.

[0021] In one specific embodiment, the central differential may have an intermediate shaft extending rearward to the central clutch and a pinion shaft extending forward to the front axle differential on its two output sides. The pinion shaft extending to the front axle differential is drive-connected to the front wheels of the front axle via the front axle differential and half-shafts. Furthermore, the central differential can be locked via a central locking clutch. The central locking clutch is preferably implemented as a diaphragm clutch that can switch 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 during all-wheel drive operation.

[0022] The center locking clutch can function in two ways, not only as a differential lock. Additionally, in the engaged state, i.e., in front-wheel drive mode, the center locking clutch ensures that drive torque is transmitted from the center differential to the front axle differential.

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

[0024] In addition, the front axle differential can be locked via a front axle locking clutch. Unlike the center 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 housing of the front axle differential can be connected to the half-shaft, that is, the front axle differential is locked.

[0025] With the powertrain according to the invention, the vehicle can operate efficiently in front-wheel drive mode, while the universal joint and, if necessary, the bevel gear transmission between the universal joint and the rear axle differential are completely disengaged from the powertrain. Switching from front-wheel drive mode to all-wheel drive mode can be fully automatic during driving and under load. The same applies to switching from all-wheel drive mode to front-wheel drive mode. Furthermore, the driving torque at the wheels can be adjusted by selectively using the three differential locks. Therefore, the electric motor drive device of the invention has a total of three differentials, namely, a front axle differential, a rear axle differential, and a center differential, and a total of five clutches, namely, a rear axle release clutch, a rear axle lock clutch, a center clutch, a center lock clutch, and a front axle lock clutch.

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

[0027] In highway operation, the rear axle locking clutch, which is a diaphragm clutch, and / or the center locking clutch, which is also a diaphragm clutch, can be disengaged and engaged in an anti-slip adjustable manner to regulate driving dynamics. Meanwhile, in highway operation, the center clutch and the rear axle release clutch are permanently engaged, while the front axle locking clutch is disengaged.

[0028] Off-road driving can be the same as on-road driving, except that the front axle locking clutch is engaged. Here, before starting off-road driving (i.e., under no load), the driver can engage the front axle locking clutch (preferably a dog clutch that cannot be switched under load). Attached Figure Description

[0029] Embodiments of the present invention will now be described with reference to the accompanying drawings. Wherein:

[0030] Figure 1 A schematic diagram illustrates the powertrain of a dual-track motor vehicle, which has a longitudinally mounted motor.

[0031] Figure 2 According to Figure 1The view shows a powertrain with a horizontally mounted motor. Detailed Implementation

[0032] exist Figure 1 The diagram illustrates the powertrain of a dual-track vehicle. Therefore, the powertrain includes an electric motor 1 mounted longitudinally along the vehicle as a power source. Downstream of the motor 1 are, for example, a transmission 3 and a spur gear stage 5 for torque conversion. The spur gear stage 5 includes a gear 7 mounted on the transmission output shaft of the transmission 16 and a gear 9 on the input side of the differential housing 11 of the central differential 13. The central differential 13 has, on its two output sides, an intermediate shaft 17 extending rearward to the central clutch 15 and a pinion shaft 21 extending forward to the front axle differential 19. According to… Figure 1 The pinion shaft 21 extending towards the front of the vehicle is connected to the ring gear 25 of the differential housing of the front axle differential 19 via a bevel gear transmission mechanism 23.

[0033] The two shafts 17 and 21 in the differential housing 11 of the central differential 13 engage with the compensating gear 31, which is rotatably supported on the differential housing 11, via their shaft bevel gear 29.

[0034] exist Figure 1 In this configuration, the front axle differential 19 is constructed in a manner substantially similar to that of the center differential 13. Therefore, the half-shaft 33 extends from the output side of the front axle differential 19 to both sides along the lateral direction of the vehicle to the front wheels 35.

[0035] exist Figure 1 In this configuration, the intermediate shaft 17 extending towards the rear of the vehicle is connected to the universal joint 39 via a central clutch 15, which is implemented as a dog clutch. This universal joint outputs through a bevel gear transmission mechanism 41 and acts on the ring gear 43 on the input side of the differential housing 45 of the rear axle differential 47. The construction of the rear axle differential 47 is substantially 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 via half-shafts 49.

[0036] In addition to the already mentioned central clutch 15, the powertrain has four other clutches, which will be described below. Thus, the front axle differential 19 can be locked via the front axle locking clutch 53. The front axle locking clutch 53 is implemented as a dog clutch that cannot be switched under load. When the locking function is activated, the differential housing 27 of the front axle differential 19 is connected to the left half-shaft 33, i.e., the front axle differential is locked. Similarly, the central differential 13 can also be locked via the central locking clutch 55. The central locking clutch 55 is implemented as a diaphragm clutch that can be switched under load. When the locking function is activated, the central locking clutch 55 connects the differential housing 11 of the central differential 13 to the pinion shaft 21 extending towards the front of the vehicle. Similarly, the rear axle differential 47 can also be locked via the rear axle locking clutch 57. The rear axle locking clutch 57 is also implemented 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 housing 27 of the front axle differential 19 to the right half-shaft 49, thus locking the rear axle differential. Additionally, a rear axle release clutch 59 is installed on the left half-shaft 49.

[0037] exist Figure 1 In this configuration, the front axle differential 19, bevel gear transmission mechanism 23, front axle locking clutch 53, central locking clutch 55, central differential 13, central clutch 15, spur gear stage 5, and transmission 3 are compactly combined in a common transmission housing to form the front axle drive unit 10. The operation of clutches 53, 55, 15, and possibly the transmission 3 can be centrally performed via a switching system not shown. Similarly, at the rear axle, the rear axle differential 47, rear axle release clutch 49, rear axle locking clutch 57, and bevel gear transmission mechanism 41 are combined to form the rear axle drive unit 50.

[0038] The vehicle can operate in the following mode: activating the front-wheel drive mode in the vehicle's energy-efficient mode. In the front-wheel drive mode, only the central locking clutch 55 is engaged, while all other clutches are disengaged. In this way, the drive torque generated in the motor 1 is guided through the transmission 16, the spur gear stage 5, and the differential housing 11 of the central differential 13 to the pinion shaft 21 of the front axle differential 19. Due to the disengaged central clutch 15 and the disengaged rear axle clutch 59, the subsystem between the central clutch 15 and the rear axle differential 47 ceases operation in the front-wheel drive mode; specifically, the universal joint 39, the bevel gear transmission mechanism 41, and the differential housing 45 of the rear axle differential 47 cease operation, while the compensating gear in the rear axle differential 47 rotates without load.

[0039] Therefore, the central locking clutch 55 functions in a dual manner in front-wheel drive mode for torque transmission on the one hand, and as a differential lock during all-wheel drive mode on the other.

[0040] The process of switching from front-wheel drive mode to rear-axle-engaged all-wheel drive mode is as follows: First, the rear axle lock-up clutch 57 is engaged. Synchronization is achieved in such a way that the universal joint 39 is accelerated to a speed related to the vehicle speed. Therefore, the clutch half of the central clutch 15 connected to the universal joint 39 synchronizes with the clutch half connected to the drive shaft 17. After the synchronization process is complete, in a further process, the central clutch 15 is engaged in any switching sequence, and the rear axle disengagement clutch 59 is engaged. With the central clutch 15 engaged and the rear axle disengagement clutch 59 engaged, the rear axle lock-up clutch 57 is disengaged. To subsequently compensate for the speed difference between the front and rear axles, the central lock-up clutch 55 is also disengaged. Because this process is performed under load in some cases, the central lock-up clutch 55 is implemented as a diaphragm clutch. Implementing the central lock-up 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 center locking clutch 55 can be disengaged and engaged in an anti-slip adjustment manner to adjust driving dynamics, while the center clutch 15 and the rear axle release clutch 59 are permanently engaged, and the front axle locking clutch 53 is permanently disengaged.

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

[0043] Therefore, off-road capability is provided via three locking clutches 53, 55, and 57, which can bridge all differentials 13, 19, and 47.

[0044] In contrast, differential locking is not required for highway operation. In this case, it is advantageous from a driving dynamics perspective that the central locking clutch 55 and the rear axle locking clutch 57 disengage and / or engage in an anti-slip adjustable manner, thereby allowing for a lesser degree of regulation of torque transmission.

[0045] Switching from all-wheel drive mode to front-wheel drive mode is performed as follows: First, engage the central locking clutch 55 to allow torque transfer from motor 1 to the front axle with the central differential 13 bridged. Then, disengage the central clutch 15 and the rear axle release clutch 59 to stop the subsystem between the central clutch 15 and the rear axle differential 47 from operation.

[0046] exist Figure 2 Another embodiment of the powertrain in a dual-track vehicle is shown in the diagram. The construction and function of this powertrain are similar to... Figure 1The powertrains shown are basically the same in structure and function. Unlike... Figure 1 The point is, in Figure 2 The central motor 1 and the front axle drive unit 10 are not mounted longitudinally, but rather transversely to the vehicle. Another bevel gear drive mechanism 61 is connected between the central clutch 15 and the universal joint 39. Furthermore, unlike... Figure 1 The drive shaft 21 extending to the front axle does not output through a bevel gear transmission mechanism, but rather through a spur gear stage 61 and acts on the front axle differential 19.

[0047] List of reference numerals

[0048] 1. Motor

[0049] 3. Transmission

[0050] 5. Spur gear stage

[0051] Gears 7 and 9

[0052] 10. Transmission device housing

[0053] 11 Differential housing

[0054] 13. Central 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. Front axle differential housing

[0062] 29-shaft bevel gear

[0063] 31 Compensating Gear

[0064] 33 Front axle half shaft

[0065] 35 front wheels

[0066] 39 Universal joint

[0067] 41. Bevel gear transmission mechanism

[0068] 43. Ring gear of the rear axle differential

[0069] 45 Differential housing

[0070] 47 Rear Axle Differential

[0071] 49 Rear axle half shaft

[0072] 50 Rear Axle Drive Unit

[0073] 51 Rear wheel

[0074] 53 Front axle locking clutch

[0075] 55. Central locking clutch

[0076] 57 Rear Axle Locking Clutch

[0077] 59 Rear axle disengagement clutch

[0078] 60 Bevel gear transmission mechanism

[0079] 61 Spur Gear Stage

[0080] FR driving direction

Claims

1. An all-wheel drive vehicle, the powertrain of which has exactly one electric motor (1), which drives only the front axle of the vehicle in front-wheel drive mode, wherein, The motor (1) can be connected to the universal joint (39) via the central differential (13) and the central clutch (15). The universal joint can be connected to the rear wheels (51) of the vehicle via the rear axle differential (47) and the half-shafts (49). When the central clutch (15) is disengaged, the rear axle is disconnected from the powertrain. When the central clutch (15) is engaged, the rear axle is connected to the powertrain. A rear axle release clutch (59) is installed in one of the half-shafts (49) of the rear axle. In front-wheel drive mode, that is, when the central clutch (15) is disengaged, the rear axle release clutch (59) is disengaged, thereby stopping the subsystem between the central clutch (15) and the rear axle differential (47). During driving, the vehicle can operate without interruption of traction. In this case, the switching from front-wheel drive mode to all-wheel drive mode is performed. In order to switch from front-wheel drive mode to all-wheel drive mode, the central clutch (15) can be engaged. The rear axle differential (47) can be locked by the rear axle locking clutch (57), which is a diaphragm clutch that can be switched under load. The rear axle locking clutch (57) functions as a synchronizing clutch. By means of the synchronizing clutch, a synchronization process is achieved before the central clutch (15) is engaged. During this synchronization process, the universal joint (39) is accelerated to a speed related to the vehicle speed, so that the clutch half of the central clutch (15) connected to the universal joint (39) can be synchronized to the speed of the clutch half of the central clutch (15) connected to the central differential (13).

2. The vehicle according to claim 1, characterized in that, When the locking function is engaged, the differential housing (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, After the synchronization process is performed in any switching sequence, the central clutch (15) engages, the rear axle release clutch (59) engages, and with the central clutch (15) engaged and the rear axle release clutch (59) engaged, the rear axle locking clutch (57) disengages and / or the central locking clutch (55) disengages.

4. The vehicle according to claim 1 or 2, characterized 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. The pinion shaft (21) is driven to the front wheel (35) of the front axle via the front axle differential (19) and the front axle half shaft (33). The central differential (13) can be locked by a central locking clutch (55), which is a diaphragm clutch that can switch under load. When the locking function is active, the differential housing (11) of the central differential (13) is connected to the pinion shaft (21) extending to the front axle differential (19) to form a central differential lock.

5. The vehicle according to claim 4, characterized in that, The central locking clutch (55) functions in two ways: it is used not only as a differential lock, but also, when engaged, ensures the transmission of drive torque from the central differential (13) to the front axle differential (19) in front-wheel drive mode.

6. The vehicle according to claim 1 or 2, characterized in that, The motor (1) drives the gear (9) on the differential housing (11) of the central differential (13) indirectly or directly.

7. The vehicle according to claim 1 or 2, characterized in that, The motor (1) drives the gear (9) on the differential housing (11) of the central differential (13) with the intermediate transmission (3) and / or the front drive stage (5) for torque conversion. The front drive stage is a spur gear stage.

8. The vehicle according to claim 4, characterized in that, The front axle differential (19) can be locked by a front axle locking clutch (53), which is a dog clutch that cannot be switched under load. When the locking function is active, the differential housing (27) of the front axle differential (19) is connected to the front axle half shaft (33) to form a front axle differential lock.

9. The vehicle according to claim 1 or 2, characterized in that, Activating the front-wheel drive mode and / or all-wheel drive mode in the vehicle's energy-saving mode can separate on-road and off-road operation.

10. The vehicle according to claim 9, characterized in that, In highway operation, the rear axle locking clutch (57) and / or the central locking clutch (55) configured as a diaphragm clutch can be disengaged and engaged in an anti-slip adjustable mode for driving dynamics control, while the central clutch (15) and the rear axle release clutch (59) are permanently engaged and the front axle locking clutch (53) is disengaged, and / or the off-road operation is designed to be the same as the highway operation except that the front axle locking clutch (53) is engaged.

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