Drive device for a motor vehicle drive train of an electric vehicle

Abstract

The invention relates to a drive device (7) for the motor vehicle drive system of an electric vehicle, containing at least one electric machine (14) with a gearbox (18) connected in series to the drive output side as the drive machine. In this context, the gearbox (18) has an input side (17) and an output side (19) with axial displacement (27) relative to each other, where the output side (19) of the gearbox (18) is connected to a distribution device (25) assigned to multiple drive outputs (9, 10) which function to connect to each drive axle (2) in the motor vehicle drive system of the electric vehicle. In order to create a drive device (7) for an electric vehicle suitable for off-road conditions, the output side (19) of the gearbox (18) is positioned with an upward and downward displacement relative to the input side (17) of the gearbox (18).

Description

[0001] The invention relates to a drive unit for a motor vehicle powertrain of an electric vehicle, comprising at least one electric motor as a drive motor, to which a transmission is connected on the output side, wherein the input and output sides of the transmission are offset from each other, and wherein the output side of the transmission is connected to a distribution unit to which at least two outputs are assigned, each serving to connect one drive axle of the electric vehicle in the motor vehicle powertrain. The invention further relates to a motor vehicle powertrain with the aforementioned drive unit and to an electric vehicle.

[0002] In electric vehicles, drive systems are known to often consist of at least one electric motor and one or more downstream transmissions. In some cases, different gears can be engaged to translate the drive motion of the at least one electric motor with different gear ratios. Such a drive system can also include a distribution device that distributes the drive motion generated by the at least one electric motor and translated by the downstream transmission(s) to multiple outputs.

[0003] German patent DE 10 2016 006 208 A1 discloses a drive unit for a motor vehicle powertrain designed for an electric vehicle in the form of a commercial vehicle. This drive unit comprises one or more electric motors to which a transmission is connected. The drive unit of DE 10 2016 006 208 A1 is designed for installation between longitudinal members of a vehicle frame of the electric vehicle, with the transmission, when the drive unit is installed, being attached to a cross member extending between the longitudinal members. In one variant, the drive unit is designed to drive several drive axles of the electric vehicle, and is equipped with two outputs for this purpose.The outputs are offset in the transverse direction of the electric vehicle relative to the electric machine(s), so that a translation of each drive movement with axis offset and distribution to the two outputs takes place via the transmission.

[0004] DE 10 2016 006 208 A1 describes a battery-electrically powered commercial vehicle, in particular a truck, comprising a ladder frame with two longitudinal members connected to each other by cross members, a gearbox, and at least one electric machine arranged on the gearbox, capable of being operated as a generator and as a motor, which can be connected to at least one axle of the commercial vehicle via the gearbox. The gearbox is attached to a cross member of the ladder frame.

[0005] Starting from the prior art described above, the object of the present invention is to realize a drive device which is suitable for an off-road electric vehicle.

[0006] This problem is solved starting from the preamble of claim 1 in conjunction with its characterizing features. The subsequent dependent claims each describe advantageous embodiments of the invention. A motor vehicle powertrain comprising a drive device according to the invention is further the subject of claims 10 and 11. Claim 12 also relates to an electric vehicle with a corresponding motor vehicle powertrain.

[0007] According to the invention, a drive unit comprises at least one electric motor as the drive motor, to which a gearbox is connected on the output side. In the gearbox, an input side and an output side are arranged with an axial offset to each other, the output side of the gearbox being connected to a distribution unit to which at least two outputs are assigned, each serving to connect one drive axle of the electric vehicle in the vehicle drivetrain.

[0008] The drive device according to the invention provides at least one electric machine, which in particular has one rotor and one stator.

[0009] Preferably, the at least one electric machine can operate in generator mode, in which it generates current by driving the respective rotor, or it can operate in electromotive mode, in which it generates a drive movement of the respective rotor by supplying it with current. According to the invention, the drive device preferably includes exactly one electric machine, although the drive device according to the invention can alternatively also include several electric machines.

[0010] Within the drive device according to the invention, a gearbox is connected downstream of the output side of the at least one electric machine, and this gearbox is equipped with an input side and an output side. The input side and the output side of the gearbox are offset from each other, i.e., they are positioned at a distance from each other on axes that are preferably parallel to each other. Preferably, the input side and the output side of the gearbox are permanently coupled to each other, so that any drive movement introduced into the gearbox at the input side is always transmitted to the output side of the gearbox.

[0011] The input side of the gearbox is connected to the at least one upstream electric machine. This connection can be permanent, preventing the rotor of the electric machine and the input side of the gearbox from rotating independently. Alternatively, the connection between the input side of the gearbox and the electric machine can be detachable, allowing the electric machine to be isolated from the input side of the gearbox.

[0012] The transmission is connected at its output side to a distribution device, which has several outputs. In the drive unit according to the invention, the distribution device is designed to distribute drive power introduced into it via the output side of the transmission, either permanently or only upon specific actuation, to the multiple outputs. In the latter case, at least one output is permanently coupled to the output side of the transmission via the distribution device. The outputs of the drive unit are configured to establish a connection to each drive axle of the electric vehicle when the drive unit is installed in a motor vehicle powertrain.Therefore, the drive device according to the invention is designed for use in an electric vehicle with a permanent all-wheel drive or a switchable all-wheel drive.

[0013] The invention now comprises the technical teaching that the output side of the transmission is offset downwards in a vertical direction relative to the input side of the transmission. In other words, the axial offset between the input and output sides of the transmission is selected such that the output side is positioned vertically below the input side in a vertical direction relative to the input side. A laterally inclined installation of the drive unit is also possible.

[0014] Alternatively, the gearbox can also be installed rotated, so that the input side is positioned vertically below the output side relative to the output side.

[0015] This type of drive unit design offers the advantage that, due to the vertical offset between the input and output shafts, drive-side components can be positioned higher when the drive unit is used in a motor vehicle powertrain, resulting in increased ground clearance for the electric vehicle. Consequently, the required ground clearance for an off-road electric vehicle can be achieved. Simultaneously, the drive unit can provide a central drive for multiple axles, enabling the realization of an electric vehicle with permanent or selectable all-wheel drive.

[0016] In contrast, the drive unit of DE 10 2016 006 208 A1 involves a transverse axle offset, which does not result in an increase in ground clearance when the drive unit is used in a motor vehicle drivetrain.

[0017] According to one embodiment of the invention, a multi-speed transmission is provided between the at least one electric motor and the gearbox, allowing different gear ratios to be selected between the respective output side of the at least one electric motor and the input side of the gearbox. Advantageously, this allows the drive motion of the at least one electric motor to be transmitted to the input side of the gearbox with different gear ratios, thereby enabling the at least one electric motor to cover a wider driving range. The multi-speed transmission can comprise planetary gear sets and / or spur gear stages to represent the different gear ratios, with the different gear ratios preferably being selected by selective actuation of the respective switching elements.Within the scope of the invention, these switching elements can be configured as positive-locking switching elements, for example as unsynchronized claw switching elements or blocking synchronization, or as friction-locking switching elements, for example in the form of a lamellar switching element. Synchronization via the motor control during the switching process is also possible.

[0018] If the drive system according to the invention provides several electric motors, a multi-speed transmission is preferably provided between the gearbox and the electric motors, via which the electric motors can be coupled individually or together with the downstream gearbox, thus enabling the different gear ratios to be achieved. In this case, the multi-speed transmission has several input shafts, each assigned to one of the electric motors. A connection to the downstream gearbox is then preferably made at a single output shaft of the multi-speed transmission. Alternatively, each electric motor can also be assigned its own multi-speed transmission, in which case the downstream gearbox must be equipped on its input side, in particular with several drive shafts, to which each electric motor with its respective, interposed multi-speed transmission is connected.

[0019] In a further development of the aforementioned embodiment, the at least one electric motor and the multi-speed transmission are combined into a single drive unit. This allows for a compact design in the drive system, as the electric motor and the associated multi-speed transmission form a single drive unit. The electric motor and the multi-speed transmission can be housed in a common casing. Alternatively, it is also conceivable that the electric motor and its casing are directly attached to a casing of the multi-speed transmission. The drive unit with the multi-speed transmission can also be designed such that the electric motor components are large enough to accommodate the multi-speed transmission components inside the electric motor.This also reduces the assembly effort for the drive device according to the invention, since the drive unit formed from electric motor and multi-speed gearbox can already be available as a pre-assembled unit.

[0020] Alternatively or additionally to the above embodiment, the at least one electric motor and the transmission are combined into a single module. This has the advantage that an overall compact design of the drive unit according to the invention can be achieved. If a multi-speed transmission is also provided between the at least one electric motor and the transmission, this multi-speed transmission is preferably also part of the module and is positioned between the electric motor and the transmission. With regard to the possibilities of the design, arrangement, and integration of a multi-speed transmission, one of the variants already described above can be implemented.

[0021] According to an alternative embodiment, the at least one electric motor and the gearbox are separate units, connected by a driveshaft. This allows the electric motor and gearbox to be positioned at a distance from each other within the drive unit, with the driveshaft enabling the supply of drive power from the at least one electric motor to the gearbox or the introduction of drive motion from the gearbox to the at least one electric motor during its generator operation. The connection to the gearbox can also be implemented in an embodiment where a multi-speed gearbox is provided between the at least one electric motor and the gearbox.This multi-speed transmission can be combined with the electric motor to form a single drive unit, with the driveshaft then connecting an output side of the multi-speed transmission to the input side of the transmission. Alternatively, the multi-speed transmission can also be located on the transmission side, in which case the driveshaft connects an output side of the at least one electric motor to a drive side of the multi-speed transmission.

[0022] In a further development of the invention, the input and output sides of the transmission are coupled to each other via at least one spur gear stage. This advantageously allows, firstly, a permanent coupling of the input and output sides of the transmission to be achieved, and secondly, the axial offset between the input and output sides to be represented.

[0023] According to a further embodiment of the invention, the transfer case comprises a differential gear, which is in particular a bevel gear differential or a planetary differential. The differential gear allows drive power to be distributed to output shafts, each of which is connected to one of the outputs. The use of a differential gear has the advantage that a permanent distribution of drive torque to the outputs, and thus, in the installed state of the transfer case, also to the respective drive axles, is achieved, with the possibility of compensating for speed differences. This makes the transfer case suitable for vehicles with permanent all-wheel drive. In the case of a bevel gear differential, a uniform torque distribution is achieved, while in the case of a planetary differential, a non-uniform distribution is also possible.

[0024] According to the invention, the differential gear can also be equipped with a locking device which, when actuated, creates a rigid connection between the output shafts, thereby eliminating the differential's compensating effect. This locking device is preferably actuated automatically, and is further preferably equipped with sensors that detect the rotational speeds of the output shafts. Based on these detected rotational speeds, the locking device can then automatically lock the differential gear if at least one criterion is met.

[0025] As an alternative to the aforementioned embodiment, one input side of the distributor is permanently coupled to a first output, while a second output can be connected to the first output via a clutch. In this variant, only the first output is permanently coupled to the input side of the distributor and thus also to the upstream transmission, while the second output is decoupled from both the input side of the distributor and the first output when the clutch is disengaged. However, when the clutch is engaged, the outputs are rigidly connected and therefore rotate at the same speed. In this case, any drive torque applied to the input side of the distributor is distributed evenly and at the same speed to both outputs.This means that the transfer case according to the invention is designed for a motor vehicle drivetrain of an electric vehicle with switchable all-wheel drive.

[0026] In the variant described above, sensors can be provided on the output shafts to detect the rotational speed of each individual output shaft. Preferably, an actuating device is then provided by which the clutch can be automatically engaged when a specific criterion is recognized as being met based on the detected rotational speeds. Ultimately, this enables the automatic engagement of a drive axle upon detection of certain conditions.

[0027] The invention also relates to a motor vehicle powertrain for an electric vehicle, which has a drive unit according to one or more of the aforementioned variants. Advantageously, this allows a powertrain for an electric vehicle with all-wheel drive or switchable all-wheel drive to be realized, thereby providing sufficient ground clearance for an off-road capable electric vehicle.

[0028] In a further development of a motor vehicle drivetrain according to the invention, at least one driven front axle is connected to one output of the drive unit and at least one driven rear axle is connected to another output of the drive unit. Particularly preferably, the drivetrain provides exactly one driven front axle and exactly one driven rear axle, wherein the front axle and the rear axle are each connected to the corresponding output of the drive unit according to the invention. A drive connection between an output of the drive unit and a drive axle is particularly preferred via an intermediate driveshaft.

[0029] The invention further relates to an electric vehicle, which is particularly preferably a commercial vehicle. This electric vehicle is equipped with a drivetrain according to one or more of the aforementioned configuration options. The electric vehicle is specifically designed as an off-road vehicle.

[0030] Advantageous embodiments of the invention, which are explained below, are illustrated in the drawings. They show: Fig. 1 a schematic representation of an electric vehicle according to a preferred embodiment of the invention; Fig. 2 a schematic view of a drive unit according to a first embodiment of the invention; Fig. 3 a side view of the drive unit made of Fig. 2 Fig. 4 a schematic representation of a drive device according to a second embodiment of the invention; Fig. 5 a side view of the drive device made of Fig. 4 ; and Figs. 6 to 8 schematic views of possible configurations of a distribution device for the drive units from the Fig. 2 and 3 or the Fig. 4 and 5 .

[0031] Fig. 1 Figure 1 shows a schematic view of an electric vehicle 1, which is specifically an off-road utility vehicle. The electric vehicle 1 has a motor vehicle powertrain 2 equipped with two drive axles 3 and 4. Drive axle 3 is a steerable front axle 5, and drive axle 4 is a non-steerable rear axle 6. Therefore, the electric vehicle 1 is equipped with permanent or selectable all-wheel drive.

[0032] Within the drivetrain 2, the two drive axles 3 and 4 can be driven via a drive unit 7, which is positioned longitudinally in the electric vehicle 1 between the drive axles 3 and 4. Specifically, an axle differential 8 of the drive axle 3 is connected to an output 9 of the drive unit 7, with the drive unit 7 also being connected via an output 10 to an axle differential 11 of the drive axle 4. A connection between the respective output 9 or 10 and the respective axle differential 8 or 11 of the respective drive axle 3 or 4 is established via an intermediate driveshaft 12 or 13, respectively.

[0033] Fig. 2Figure 1 shows a schematic detail view of the drive unit 7, which is configured according to a first embodiment of the invention. This drive unit 7 comprises an electric machine 14, which – not shown here – consists of a stator and a rotor. The electric machine 14 can be operated both as a generator and as an electric motor.

[0034] The rotor of the electric machine 14 is preferably connected via a rotor shaft to a drive side of a downstream multi-speed gearbox 15, wherein the multi-speed gearbox 15 is configured as shown in Fig. 3As can be seen, the electric machine 14 is combined to form a drive unit 16. In the multi-speed transmission 15, different gear ratios can be selected between the drive side and an output side of the multi-speed transmission 15, wherein the multi-speed transmission 15 is equipped with planetary gear sets and / or spur gear stages to achieve these different gear ratios. Preferably, the gear ratios can be selected by selective actuation of switching elements, which can be designed as friction-locking or positive-locking switching elements.

[0035] The output side of the multi-speed transmission 15 is connected to an input side 17 of a downstream transmission 18, in which a drive movement initiated at the input side 17 is continuously translated to an output side 19 of the transmission 18. The input side 17 of the transmission 18 is formed by a shaft 20 on which a spur gear 21 of a spur gear stage 22 is fixedly mounted. This spur gear 21 is in mesh with a spur gear 23 of the spur gear stage 22, with the spur gear 23 forming both the output side 19 of the transmission 18 and also an input side 24 of a distribution device 25 following the transmission 18.The distribution device 25 is combined with the gearbox 18 and the drive unit 16, consisting of an electric motor 14 and a multi-speed gearbox 15, to form a module 26, in that the distribution device 25 and the gearbox 18 are combined in a housing to which the drive unit 16 is also directly attached. The latter is particularly evident in . Fig. 3 to recognize.

[0036] To use the all-terrain electric vehicle 1 from Fig. 1 To achieve the greatest possible ground clearance, the input side 17 and the output side 19 of the gearbox 18 are located in the vertical direction under an axis offset 27 to each other, which also means that the drive unit 16 is arranged higher than the outputs 9 and 10.

[0037] Furthermore, the Fig. 4 and 5Views of a drive unit 28, which is designed according to a second embodiment of the invention and is also used in the motor vehicle drive train 2 in Fig. 1 can be used. This drive unit 28 essentially corresponds to the drive unit 7 according to the Fig. 2 and 3 , with the difference that the drive unit 16, formed from the electric motor 14 and the multi-speed transmission 15, is arranged as a separate unit from the transmission 18 and the distribution device 25. A connection between the drive unit 16 and the input side 17 of the transmission 18 is established via a driveshaft 29. Consequently, the drive unit 16 can also be positioned further upwards relative to the input side 17. Otherwise, the design option corresponds to the Fig. 4 and 5 according to the variant Fig. 2 and 3, so that reference is made to what has been described here.

[0038] The Figs. 6 to 8 show possible configurations of the distribution device 25, as they are used in the drive devices 7 and 28 respectively from the Fig. 2 and 3 or the Fig. 4 and 5 This can be achieved. It shows Fig. 6 An embodiment of the distributor 25, in which the distributor 25 has a bevel gear differential 30, via which a drive power introduced at the input side 24 of the distributor 25 is distributed to output shafts 31 and 32, which each form the outputs 9 and 10. The input side 24 is non-rotatably connected to a differential carrier 33 of the bevel gear differential 30 in the form of the spur gear 23.

[0039] In the differential housing 33, two compensating bevel gears 34 and 35 are rotatably mounted on a bolt 36, the compensating bevel gears 34 and 35 each meshing with output bevel gears 37 and 38, which are each fixedly mounted on one of the output shafts 31 and 32, respectively. The bevel gear differential 30 thus ensures an even distribution of torque to the two outputs 9 and 10, compensating for any differences in rotational speed.

[0040] However, it shows Fig. 7 A variant of the distributor device 25, in which the distributor device 25 has a planetary differential 39. The planetary differential 39 consists of a sun gear 40, a planet carrier 41 and a ring gear 42, wherein several planet gears 43 are rotatably mounted in the planet carrier 41, each of which is in mesh with both the sun gear 40 and the ring gear 42.

[0041] The planetary gear 41 is non-rotatably connected to the input side 24 in the form of the spur gear 23. While the sun gear 40 is non-rotatably connected to the output shaft 31, the ring gear 42 is non-rotatably connected to the output shaft 32. In the planetary differential 39, torque is distributed to the outputs 9 and 10, potentially compensating for speed differences; however, unlike the bevel gear differential 30, an uneven torque distribution is possible.

[0042] At the in Fig. 8In the illustrated embodiment of the distributor 25, the output shaft 32 is permanently connected to the input side 24 of the distributor 25. However, the output shaft 31 can be non-rotatably connected to the output shaft 32, and thus also to the input side 24, via an intermediate coupling 44. This ensures that the drive power introduced at the input side 24 is distributed evenly between the two output shafts 31 and 32. No compensation for speed differences takes place in this configuration. This differs from the two preceding variants described above. Fig. 6 or 7 is in the execution of the distribution device 25 according to Fig. 8 Furthermore, no permanent all-wheel drive is achieved, since no power flow to the output shaft 31 and thus to the output 10 occurs when the clutch 44 is open. In the case of the design according to Fig. 6 The all-wheel drive can be engaged by actuating clutch 44.

[0043] Using the inventive designs of a drive unit, a compact drive for an off-road electric vehicle with high ground clearance can be achieved. Reference sign

[0044] 1 Electric vehicle 2 Automotive powertrain 3 Drive axle 4 Drive axle 5 Front axle 6 Rear axle 7 Drive unit 8 Axle differential 9 Output 10 Output 11 Axle differential 12 Drive shaft 13 Drive shaft 14 Electric motor 15 Multi-speed transmission 16 Drive unit 17 Input side 18 Transmission 19 Output side 20 Shaft 21 Spur gear 22 Spur gear stage 23 Spur gear 24 Input side 25 Distributor 26 Module 27 Axle offset 28 Drive unit 29 Drive shaft 30 Bevel gear differential 31 Output shaft 32 Output shaft 33 Differential cage 34 Differential bevel gear 35 Differential bevel gear 36 Bolt 37 Output bevel gear 38 Output bevel gear 39 Planetary differential 40 Sun gear 41 Planetary web 42 Ring gear 43 Planetary gears 44 Clutch

Claims

1. Drive device (7; 28) for a motor vehicle drive train (2) of an electric vehicle (1), comprising at least one electric machine (14) as a drive machine, which is connected downstream of a gearbox (18) on the output side, wherein, in the gearbox (18), an input side (17) and an output side (19) lie at an axial offset (27) with respect to each other, and wherein the output side (19) of the gearbox (18) is in connected to a distributor (25), which is assigned to a plurality of outputs (9, 10) which, in the motor vehicle drive train (2), each serve for the attachment of a drive axle (3, 4) of the electric vehicle (1), characterized in that the output side (19) of the gearbox (18) is offset downwards in a vertical direction with respect to the input side (17) of the gearbox (18).

2. Drive device (7; 28) according to Claim 1, characterized in that a multi-speed gearbox (15) is provided between the at least one electric machine (14) and the gearbox (18), via which multi-speed gearbox different transmission ratios between a respective output side of the at least one electric machine (14) and the input side (17) of the gearbox (18) can be selected.

3. Drive device (7; 28) according to Claim 2, characterized in that the at least one electric machine (14) and the multi-speed gearbox (15) are combined to form a drive unit (16).

4. Drive device (7) according to any one of Claims 1 to 3, characterized in that the at least one electric machine (14) and the gearbox (18) are combined to form a module (26).

5. Drive device (28) according to any one of Claims 1 to 3, characterized in that the at least one electric machine (14) and the gearbox (18) are present as separate units, wherein a connection is established between these units via a propeller shaft (29).

6. Drive device (7; 28) according to any one of the preceding claims, characterized in that the input side (17) and the output side (19) of the gearbox (18) are coupled to each other via at least one spur gear stage (22).

7. Drive device (7; 28) according to any one of the preceding claims, characterized in that the distributor (25) comprises a differential gear, in particular a bevel gear differential (30) or a planetary differential (39), wherein a drive power can be split via the differential gear between output shafts (31, 32), each of which is connected to one of the outputs (9, 10).

8. Drive device according to Claim 7, characterized in that the differential gear is assigned a locking device.

9. Drive device (7; 28) according to any one of Claims 1 to 6, characterized in that an input side (24) of the distributor (25) is permanently coupled to a first output (9), whereas a second output (10) is connectable via a clutch (44) to the first output (9).

10. Motor vehicle drive train (2) for an electric vehicle (1), in particular in the form of a commercial vehicle, comprising a drive device (7; 28) according to one or more of Claims 1 to 9.

11. Motor vehicle drive train (2) according to Claim 10, characterized in that at least one drivable front axle (5) is drive-connected to an output (9) of the drive device (7; 28), and at least one drivable rear axle (6) is drive-connected to another output (10) of the drive device (7; 28).

12. Electric vehicle (1), in particular in the form of a commercial vehicle, comprising a motor vehicle drive train (2) according to Claim 10 or 11.