Electric drive system

Abstract

The invention relates to an electric drive system (1) with at least two drive trains that are at least partially separate from each other, a first electric machine (2) and a second electric machine (3), wherein the drive trains can be individually coupled to the first or second electric machine (2, 3), wherein at least one loose gear (18 to 21) is arranged for coupling, wherein several switching elements (S1, S1'; S2, S2') are arranged for coupling at least one of the loose gears (18 to 21) to a respective input shaft (4, 5) in order to selectively transmit its drive force to a respective output shaft (13), wherein the switching elements (S1, S1'; S2, S2') are configured to decouple the respective loose gear (18 to 21) from the input shaft (4, 5) when the electric drive system (1) is operated in a partial load operation with a power requirement below a certain threshold.

Description

[0001] The invention relates to an electric drive system, in particular for a motor vehicle, according to the type defined in the preamble of claim 1.

[0002] In addition to hybridized drive systems, which use both an internal combustion engine and electric motors to power a vehicle, purely electric drive systems are also becoming increasingly important. These can include a drive system for a purely electrically driven axle with a gear ratio that can be shifted via a transmission, in particular with multiple gear stages. As prior art, the present application is based on DE 10 2008 002 380 A1. This shows some of the features of the preamble of the applicable claim, but unlike the present invention, it is based on a hybrid system and not on a purely electric drive system. The design provides for a group transmission with a main group and a range group, which has a planetary gear set.Two electric motors are provided, each driving its own input shaft of the main group, while an internal combustion engine can drive the main group's output shaft via a switchable clutch. This main group output shaft is connected to the sun gear of the range group's planetary gear set, whose planetary carrier represents the output of the hybrid drive system.

[0003] DE 10 2020 005 394 A1 describes an electric drive system with two electric machines and a group transmission with a main group and a range group, wherein the range group has a planetary gear set, wherein a first input shaft of the main group is coupled or can be coupled to the first electric machine in such a way that torques originating from the first electric machine can be introduced into the group transmission via the first input shaft, wherein a second input shaft of the main group is coupled or can be coupled to the second electric machine in such a way that an output shaft of the main group is permanently coupled to a first element of the planetary gear set in a torque-transmitting manner, and wherein a second element of the planetary gear set is permanently coupled to an output shaft of the group transmission in a torque-transmitting manner.Exactly two loose wheels are arranged coaxially to the first input shaft, wherein exactly two further loose wheels are arranged coaxially to the second input shaft, wherein the two input shafts are coupled or can be coupled to the output shaft via exactly two fixed wheels arranged coaxially to the output shaft, and wherein a first fixed wheel is permanently meshed with the first and the third loose wheel, and a second fixed wheel is permanently meshed with the second loose wheel and the fourth loose wheel.

[0004] WO 2023 / 031206 A1 describes an electric drive train for a work machine, comprising a first electric motor with a first motor shaft and a second electric motor with a second motor shaft, and comprising a shiftable transmission with an output shaft. The first motor shaft represents a first input shaft of the transmission and the second motor shaft represents a second input shaft of the transmission. The first input shaft is parallel to the output shaft, but at a different distance from the second input shaft.

[0005] The object of the invention is to create an electric drive system with the features in the preamble of claim 1, which enables comfortable and long-lasting operation.

[0006] According to the invention, this object is achieved by an electric drive system having the features in claim 1, and here in particular in the characterizing part of claim 1.

[0007] Advantageous embodiments of the invention are the subject of the subclaims.

[0008] An electric drive system is proposed with at least two drive trains that are at least partially separate from one another and with a first electric machine and a second electric machine, wherein the drive trains can be individually coupled to the first or second electric machine, wherein at least one idler gear is arranged for coupling, wherein a plurality of switching elements are arranged for coupling at least one of the idler gears to a respective input shaft in order to selectively transmit its drive force to a respective output shaft. According to the invention, the switching elements are configured to decouple the respective idler gear from the input shaft when the electric drive system is operated in partial load mode with a power requirement below a certain threshold.

[0009] The purely electric drive system according to the invention, similar to the hybrid drive system in the prior art mentioned at the outset, uses two electric motors which drive an output shaft of the group transmission via a group transmission with a main transmission and a range group comprising a planetary gear set. These then drive, for example, one or more driven axles of a vehicle, in particular a commercial vehicle. According to the invention, exactly two idler gears are provided coaxially to the first input shaft of the main group, as well as coaxially to the second input shaft of the main group. This creates a total of four discretely shiftable gears via the two electric motors and, if required, corresponding virtual intermediate gears, without the need for corresponding expenditure on additional idler gears, as would be the case, for example, with a hybrid drive system.

[0010] By using exactly two idler gears on each of the two input shafts and, correspondingly, exactly two fixed gears to connect the output shaft of the main group to its input shafts, whereby one of the idler gears of the input shafts meshes with the first fixed gear of the output shaft and the two other idler gears of the respective input shaft mesh with the second fixed gear of the output shaft, a design is created that enables shifting under load within the respective range group position. This is possible with simple claw shift elements, as provided in a particularly advantageous development of the electric drive system according to the invention.In contrast to complex and wear-sensitive friction shift elements, shifting can now be carried out simply, comfortably and in a wear-optimized manner by appropriately shifting the idler gears on the respective input shaft under load and with synchronization by means of the electric machine.

[0011] A further advantage is achieved by positioning the electric motors on the two different input shafts, allowing for virtual intermediate gears, which particularly improves starting performance. This is especially true for heavy vehicles, which is why the preferred, but not exclusive, application is in commercial vehicles.

[0012] A further advantage resulting from the use of the two electric machines is that in partial load operation, which for example in long-distance commercial vehicle transport accounts for around 70% of the total driving share, one of the two electric machines can be shut down, for example by decoupling, which has an overall impact on the service life and efficiency of these units.

[0013] According to a very advantageous development of the concept, a third fixed gear can be arranged coaxially with the output shaft of the main group, permanently meshing with a fourth fixed gear, which in turn is non-rotatably connected to the first element of the planetary gear set. Such a connection of the planetary gear set, and thus the range group of the group transmission, allows for an efficient and compact design.

[0014] A rotationally fixed connection in the sense of the invention is understood to mean a connection between rotating elements arranged coaxially to one another, which connects these elements to one another in such a way that they rotate at the same angular velocity.

[0015] As already indicated above, the idler gears are correspondingly switchably connected to their respective input shafts, wherein according to a very advantageous embodiment of the invention, a first and a second switching element for the first and second idler gears and the third and fourth idler gears are provided in the region of each of the input shafts, wherein the respective first switching element is designed to connect the first or third idler gear to its respective input shaft, and wherein the respective second switching element is designed to connect the second or fourth idler gear to its respective input shaft. In total, four switching elements are provided in the region of the input shafts, one for each of the idler gears. These are designed in such a way that they optionally connect the idler gear to its input shaft or not, so that the idler gear rotates freely relative to the input shaft.This is sufficient to achieve a total of four gears, whereby these gears can be powershifted within the same position of the range group, and whereby the drive can be provided either by one, the other or both electric motors.

[0016] According to a further, highly advantageous embodiment of this concept, the first and second shifting elements of the respective input shaft are combined to form a double shifting element with a neutral position and an actuator. This use of a double shifting element for the first and second shifting elements of the respective input shaft ultimately reduces the total required number of elements to two double shifting elements, one for each input shaft. Each of these double shifting elements can be controlled via just one actuator, thus also reducing the effort required for the actuators. This overall reduces the complexity of the design and saves space, installation space, and components.

[0017] Within the range group, according to a very advantageous development of the electric drive system according to the invention, a brake switching element is provided for locking the third element of the planetary gear set. This allows the gear ratio of the range group to be changed. Another very advantageous embodiment further provides that, alternatively or in particular additionally, a locking switching element is provided for locking the first and third elements of the planetary gear set.

[0018] According to an extremely advantageous further development, in which the locking switching element and the brake switching element are both present, these can also be combined to form a double switching element with an actuator, so that here too the effort is reduced accordingly, comparable to that above with regard to each of the input shafts.

[0019] As already mentioned above, the rotors of the two electric machines can be coupled or coupleable to the respective input shaft of the main group. According to an extremely advantageous development of the electric drive system according to the invention, the rotor of the first electric machine is connected in a rotationally fixed manner to the first input shaft, and a rotor of the second electric machine is connected in a rotationally fixed manner to the second input shaft. This eliminates the need for an additional shifting or clutch element between the rotors of the respective electric machines and the input shafts, since the input shafts are already switchably connected to the idler gears, and when the respective shifting elements of the idler gears are in the neutral position, they ultimately remain decoupled from the output shaft of the main group of the group transmission, making the additional clutch elements unnecessary, thus saving costs, installation space, and weight.

[0020] Within the range group, according to an exceptionally advantageous development of the electric drive system according to the invention, it can be provided that a sun gear of the planetary gear set is designed as the first element, a planet carrier as the second element, and a ring gear as the third element of the planetary gear set. In this case, the range group is connected to the input shaft via a connection to the sun gear, the output via the planet carrier, while the ring gear, according to the advantageous embodiment described above, can be braked via the brake switching element and / or directly connected to the sun gear via the interlocking switching element in a rotationally fixed manner.

[0021] The first and second shifting elements on the respective input shaft can, as already mentioned above, be designed as positive-locking shifting elements, in particular as claw shifting elements. These have the great advantage of being largely wear-free. Due to the special configuration of the group transmission according to the invention, they can also be shifted under load, whereby any resulting power loss can be fully or at least partially compensated by boosting with the other electric motor. This motor can therefore take over synchronization to enable highly comfortable shifting despite the positive-locking shifting elements.

[0022] The drive trains are partially separated and can be mechanically decoupled for shutdown. Furthermore, a load point increase is possible. This reduces losses (particularly mechanical, electrical, and hydraulic losses).

[0023] The purely electric drive system according to a further aspect of the invention, similar to the hybrid drive system in the prior art mentioned at the outset, uses two electric motors which drive driven wheels of a vehicle, in particular a commercial vehicle, via a group transmission with a main transmission and a range group. According to the invention, exactly two loose gears are provided coaxially to the first input shaft of the main group, as well as coaxially to the second input shaft of the main group. This creates a total of four discretely shiftable gears via the two electric motors and, if necessary, corresponding virtual intermediate gears, without the need for corresponding expenditure on additional loose gears. The range group comprises two planetary gear sets, each of which is arranged on the output side of a differential.The differential is connected on the input side to the output shaft of the main group, according to a very advantageous design via a spur gear stage. The range group is thus relocated to the area of ​​the axles and wheels and is now located directly in their area in the form of two planetary gear sets for each of the driven wheels. The main group of the group transmission can thus be implemented simply and efficiently and only drives the differential, preferably via the spur gear stage mentioned above. While the range group, in the form of the planetary gear sets assigned to the respective driven wheel, is only designed after the differential in the direction of power flow in the case of the vehicle drive.

[0024] A further advantage is achieved by positioning the electric motors on the two different input shafts, allowing for virtual intermediate gears, which particularly improves starting performance. This is especially true for heavy vehicles, which is why the preferred, but not exclusive, application is in commercial vehicles.

[0025] A further advantage resulting from the use of the two electric machines is that in partial load operation, which, for example, accounts for around 70% of the total driving share in long-distance commercial vehicle transport, one of the two electric machines can be shut down, which has an overall impact on the service life and efficiency of these units.

[0026] Within the range group, according to a very advantageous development of the electric drive system according to the invention, two shifting elements are provided for each planetary gear set. The first shifting element can lock the first and third elements, while the second shifting element can lock the third element of the respective planetary gear set. This allows the gear ratio of the range group to be changed accordingly.

[0027] According to an extremely advantageous development of the invention, the first switching element can be combined as a blocking switching element and the second switching element as a brake switching element to form a double switching element with an actuator, so that the effort is also reduced here.

[0028] As already indicated above, the idler gears are correspondingly switchably connected to their respective input shafts, wherein according to a very advantageous embodiment of the invention, a third and a fourth switching element for the first and second idler gear or the third and fourth idler gear are provided in the region of each of the input shafts, wherein the respective third switching element is designed to connect the first or third idler gear to its respective input shaft, and wherein the respective fourth switching element is designed to connect the second or fourth idler gear to its respective input shaft. In total, four switching elements are provided here in the region of the two input shafts, one for each of the idler gears. These are designed in such a way that they optionally connect the idler gear to its input shaft or not, so that the idler gear rotates freely relative to the input shaft.This is sufficient to achieve a total of four gears, whereby these gears can be powershifted within the same position of the range group, and whereby the drive can be provided either by one, the other or both electric motors.

[0029] The third and fourth shift elements of the respective input shaft can be combined into a double shift element with a neutral position and an actuator. This use of a double shift element for the third and fourth shift elements of the respective input shaft ultimately reduces the total number of required elements to two double shift elements, one for each input shaft. Each of these double shift elements can be controlled via just one actuator, thus also reducing the effort required for the actuators. This overall reduces the complexity of the design and saves space, installation space, and components.

[0030] A further highly advantageous embodiment of the electric drive system according to the invention can provide for the differential to be designed as a differential with a switchable differential lock. This switchable differential lock, which would form a fifth shifting element, can then be engaged as needed, regardless of the respective gear position, in order to establish a direct connection between the two axles and the range group driven by the respective planetary gears through these driven wheels. Any slippage, spinning of one wheel relative to the other, or the like can then be prevented in a conventional manner by actuating this fifth shifting element of the switchable differential lock of the differential.

[0031] As already mentioned above, the rotors of the two electric machines can be coupled or coupleable to the respective input shaft of the main group. According to an extremely advantageous development of the electric drive system according to the invention, the rotor of the first electric machine is connected in a rotationally fixed manner to the first input shaft, and a rotor of the second electric machine is connected in a rotationally fixed manner to the second input shaft. This eliminates the need for an additional shifting or clutch element between the rotors of the respective electric machines and the input shafts, since the input shafts are already switchably connected to the idler gears, and when the respective shifting elements of the idler gears are in the neutral position, they ultimately remain decoupled from the output shaft of the main group of the group transmission, making the additional clutch elements unnecessary, thus saving costs, installation space, and weight.

[0032] A rotationally fixed connection in the sense of the invention is understood to mean a connection between rotating elements which connects them to one another in such a way that they rotate at the same angular velocity.

[0033] Within the range group, according to an exceptionally advantageous development of the electric drive system according to the invention, it can be provided that a sun gear of the respective planetary gear set is designed as the first element, a planet carrier as the second element, and a ring gear as the third element of the planetary gear set. In this case, the range group is connected to the differential via a connection of the respective sun gear to the axles, the output via the planet carrier connected to the respective wheels, while the ring gear, according to the advantageous embodiment described above, can be braked via the switching element and / or directly locked to the sun gear in a rotationally fixed manner.

[0034] The third and fourth shift elements on the respective input shaft can, as already mentioned above, be designed as positive-locking shift elements, in particular as dog-type shift elements. These have the great advantage of being largely wear-free. Due to the special configuration of the group transmission according to the invention, they can also be shifted under load, whereby any resulting power loss can be fully or at least partially compensated for by boosting with the other electric motor. This motor can therefore take over synchronization to enable highly comfortable shifting despite the positive-locking shift elements.

[0035] The inventive solution enables increased efficiency through mechanical decoupling of electrical machines, with or without drivetrain components (transmission parts). This creates the possibility of increased efficiency in the partial load range when less power is required. Furthermore, load-interruption-free shifting is possible.

[0036] Embodiments of the invention are explained in more detail below with reference to drawings.

[0037] Showing: Fig. 1 a schematic wheel set plan of a possible structure of an electric drive system according to the invention, Fig. 2 a shift table describing the position of the shift elements in four gears, Fig. 3 a schematic wheel set plan of a possible structure of an electric drive system according to the invention and Fig. 4 a shift table describing the position of the shift elements in four gears.

[0038] Corresponding parts are provided with the same reference numerals in all figures.

[0039] In the presentation of the Fig. 1 shows an electric drive system, designated overall by 1. This system has a first electric machine 2 and a second electric machine 3. A rotor of the first electric machine 2 is rotationally fixed to a first input shaft 4, and a rotor of the second electric machine 3 is rotationally fixed to a second input shaft 5. The input shafts 4, 5 are part of a main group 6 of a group transmission 7. An output shaft 8 of the main group 6 of the group transmission 7 is coupled to a range group 9, which has a planetary gear set 10. Here, the output shaft 8 of the main group 6 is connected to a sun shaft 11 of the planetary gear 10 of the range group 9. An output shaft 13 of the group transmission 7 is driven via a planetary carrier 12. The output shaft 13 meshes via a gear 14 with a differential gear 15, which in turn is rotationally fixed to a differential cage of a differential gear 16.Finally, two driven wheels 17 of an electrically driven axle of a vehicle, in particular a commercial vehicle, are driven via the differential gear 16. The differential gear 16 is considered to be part of general technical knowledge, so it need not be discussed further here. It is illustrated here as an example of a differential gear 16 with a switchable differential lock.

[0040] With regard to a torque flow from the electric machines 2, 3 to the wheels 17, the electric machines 2, 3, the main group 6, the range group 9, the differential gear 15 and the wheels 17 are arranged one after the other in the order mentioned.

[0041] A first idler gear 18 and a second idler gear 19 are arranged on the first input shaft 4 of the main group 6. A third idler gear 20 and a fourth idler gear 21 are arranged on the second input shaft 5. In addition, shifting elements S1 and S2 or S1' and S2' are arranged on the respective input shafts 4, 5 in such a way that they can each rotationally connect the idler gears 18, 19 and 20, 21, which are arranged coaxially to the respective input shafts 4, 5, to the respective input shafts 4, 5. Preferably, the shifting elements S1 / S2 and S1' / S2' are designed as double shifting elements with a neutral position, as shown here. They are controlled by a single actuator for each double shifting element S1 / S2.

[0042] The first idler gear 18 and the third idler gear 20 of the respective input shaft 4, 5 mesh with a first fixed gear 22 on the output shaft 8. The second idler gear 19 and the fourth idler gear 21 mesh with a second fixed gear 23 on the output shaft 8. The input shafts 4, 5 and the output shaft 8 are connected to each other exclusively via these two fixed gears 22, 23. Unlike in the gear set diagram shown here, they are typically not arranged in one plane. Therefore, a third fixed gear 24 can be placed between the two fixed gears 22, 23, which meshes with a fourth fixed gear 25 on the sun shaft 11 of the planetary gear set 10 and thus drives a sun 26 of the planetary gear set 10 when the output shaft 8 of the main group 6 of the group transmission 7 is driven. The fourth fixed gear 25 is permanently connected to the sun 26 of the planetary gear set 10.The planetary gear set 10, used as range group 9, is thus driven by the output shaft 8 of the main group 6 via the third gear 24 and the fourth gear 25. In the gear set diagram, the fact that the third fixed gear 24 permanently meshes with the fourth fixed gear 25 is indicated by a dashed line.

[0043] Planet gears 27 on the planet carrier 12 of the planetary gear set 10 mesh accordingly with the sun gear 26 and a ring gear 28 as the third element of the planetary gear set 10. The drive is therefore via the sun gear 26 as the first element, and the output is via the planet gears 27 or their planet carrier 12, which represents the second element of the planetary gear set. If necessary, the ring gear 28 can be braked using a brake switching element S3. The ring gear 28 is then connected in a rotationally fixed manner, for example, to the housing of the group transmission 7 and therefore does not rotate. This results in a first gear ratio of the range group 9. Using a blocking switching element S4, which in turn can be combined with the brake switching element S3 as a double switching element, it is also possible to connect or block the sun gear 26 as the first element of the planetary gear set 10 with the ring gear 28.This results in a different gear ratio between the sun gear shaft 11, which acts as the input shaft into the range group 9, and the planet gear carrier 12, which is connected to the output shaft 13.

[0044] In the presentation of the Fig. 2, the four individually shiftable gears are shown in principle using a shift matrix. The first column shows the respective gear, the second column the position of the first shift element S1 or the first shift element S1' on the respective input shaft 4, 5. The second column shows the second shift element S2 or the second shift element S2', the third column the state of the third shift element, i.e. the brake shift element S3, and the fourth column the state of the interlock shift element S4. In first gear, the shift element S1 and / or the shift element S1' is engaged, so the first idler gear 18 or the third idler gear 20 are connected to the respective input shaft 4 or 5, depending on which of the two electric machines 2, 3 is driving the motor, although both can also be driving the motor if necessary.At the same time, the brake switching element S3 is connected, so that the ring gear 28 is braked in a rotationally fixed manner, for example, to the housing of the group transmission 7. Without this switching position changing within the range group 9, it is now possible to change from first to second gear by releasing the switching element S1 or S1' and engaging the switching element S2 or S2', even under load, whereby this switching process can be synchronized by the electric motors 2, 3 if necessary. It is therefore very convenient to switch between gears 1, 2 or 3, 4 and to make the two related gears 1, 2 or 3, 4 powershiftable within the respective position of the range group 9. For this, and this is a decisive advantage over the prior art, no friction switching element is required, but rather the switching elements S1 and S2 orS1' and S2' can be designed as positive-locking shift elements, particularly as dog-type shift elements. This shift pattern is repeated for third and fourth gears, whereby, unlike gears 1 and 2, range group 9 is now shifted such that the locking shift element S4 is active and the brake shift element S3 is released accordingly.

[0045] By positioning the two electric motors 2, 3 on different input shafts 4, 5 and thus ultimately on different gears, virtual intermediate gears can also be enabled by driving both electric motors 2, 3 differently onto the output shaft 8. The intermediate gears achieved in this way can particularly improve the starting performance of heavy vehicles, such as commercial vehicles. During regular operation, which is very often partial load operation, the operation of one of the two electric motors 2, 3 is then sufficient, so that the other electric motor 2, 3 and the parts of the main group 6 of the group transmission 7 connected to it do not need to be used and can be decoupled, thus reducing wear, increasing efficiency and extending the service life of the structure.

[0046] In the presentation of the Fig. 3 shows an electric drive system, designated 1. The Fig. 1 The area outlined by the dotted line is duplicated, as indicated by the reference "2x." This area has a first electric machine 2 and a second electric machine 3.

[0047] These are non-rotatably and directly connected to a first input shaft 4 and a second input shaft 5 in a main group designated 6 of a group transmission 7. An output shaft 8 of the main group 6 of the group transmission 7 comprises, shown centrally, a spur gear stage 10 with a fixed gear 14, which in turn meshes with a gear 15 of a differential 16 belonging to the spur gear stage 10. The differential 16 drives two driven wheels 17, indicated by way of example, of an electrically driven axle of a vehicle, in particular a commercial vehicle. The differential 16 is shown by way of example as a differential with a switchable differential lock.

[0048] A first idler gear 18 and a second idler gear 19 are arranged on the first input shaft 4 of the main group 6. A third idler gear 20 and a fourth idler gear 21 are arranged on the identical second input shaft 5. In addition, shifting elements S3 and S4 or S3' and S4' are arranged on the respective input shafts 4, 5 in such a way that they can rotationally connect the idler gears 18, 19 and 20, 21, which are arranged coaxially to the respective input shafts 4, 5, to the respective input shafts 4, 5. Preferably, the shifting elements S3 / S4 and S3' / S4' are each designed as double shifting elements with a neutral position, as shown here. They are controlled by a single actuator per double shifting element.

[0049] The first idler gear 18 and the third idler gear 20 of the respective input shaft 4, 5 mesh with a first fixed gear 22 on the output shaft 8. The second idler gear 19 and the fourth idler gear 21 mesh with a second fixed gear 23 on the output shaft 8. The input shafts 4, 5 and the output shaft 8 are connected to each other exclusively via these two fixed gears 22, 23. The third fixed gear 14 mentioned above is placed between the two fixed gears 22, 23, which meshes with the gear 15 of the differential 16 and thus drives this on its input side 11. When the output shaft 8 of the main group 6 of the group transmission 7 is driven, two axles 13 with the driven wheels 17 are driven on the output side 12 of the differential 16.

[0050] A range group 9 here consists of two planetary gear sets 24, 25, which are arranged between the output side 12 of the differential 16 or the axles 13 and the driven wheels 17. The planetary gear sets 24, 25 can, for example, be integrated into the wheels 17. The output is each via a planet carrier 29 directly to the wheels 17. Planet gears 27 on the planet carrier 29 of the respective planetary gear set 24, 25 mesh accordingly with a sun gear 26 and a ring gear 28 of the respective planetary gear set 24, 25. The drive is therefore via the sun gear 26 as the first element, the output via the planets 27 or their planet carrier 29 as the second element. If necessary, the ring gear 28 as the third element can be braked using a switching element S1 as a brake switching element. The ring gear 28 is then non-rotatably connected, for example, to the housing of a wheel suspension 30 or the like, and accordingly does not rotate. This results in a first gear ratio of range group 9.Using the respective switching element S2 as a blocking switching element, the sun gear 26, as the first element of the respective planetary gear set 24, 25, can be connected or blocked with the ring gear 28. This results in a different gear ratio between the axle 13, which acts as the input shaft to the respective planetary gear sets 24, 25 of the range group 9, and the planetary gear carrier 29, which is connected to the wheels as the output.

[0051] In the presentation of the Fig. 4, the four individually shiftable gears are shown in principle using a shift matrix. The first column shows the number of the respective gear stage, the second column shows the position of the double shift element S1 / S2 of the planetary gear set 24 shown on the left, formed from the first and second shift elements S1, S2. The second column shows three shift positions for this double shift element S1 / S2, namely a shift position on the left, which represents the braking shift position for the planetary gear set 24, a middle neutral position, as shown in the illustration of the Fig.3 and a right-hand position, which represents the locking switching position. The same structure is selected in the following third column. The switching positions now show the corresponding switching positions of the double switching element S1 / S2 of the other planetary gear set 25, formed from the first and second switching elements S1, S2. Since the structure here is essentially a mirror image of the differential 16, the left-hand column represents the locking switching position and the right-hand column represents the braking switching position, while according to the middle column, the structure is in the neutral position shown here, which is a state not used in practice.

[0052] The two further columns, each labeled S3 / S3' and S4 / S4', refer to the third and fourth shift elements located on the respective input shaft 4, 5. Here, too, three positions can be seen: in the middle is the neutral position, on the right is the position in which the first or third idler gear 18, 20 of the respective input shaft 4, 5 is connected to it in a rotationally fixed manner, and on the right is the position in which the second or fourth idler gear 19, 21 is connected to its respective input shaft 4, 5.

[0053] In the example of the shift matrix shown here, in first gear, both electric motors 2, 3 drive via the second and fourth idler gears 19, 21, which in turn drive the output shaft 8 of the group transmission 6 via the fixed gears 22, 23. The differential 16 is then driven via the spur gear stage 10 with the fixed gears 14 and 15. The driven wheels 17 are then driven via the axles 13 between the output side 12 of the differential 16 and the planetary gear sets 24, 25 of the range group 9. In both cases, the double shift elements S1 / S2 of the respective planetary gear sets 24, 25 are in the locked position of the ring gear 28. When changing to the second gear, the coupling is simply switched from the second or fourth idler gear 19, 21 to the first or third idler gear 18, 20 on the respective input shaft 4, 5.When changing from the second to the third gear, the brake connection of the two planetary gear sets 24, 25 is changed to their blocking connection and in the group transmission 6 the gear changes back to the second and fourth idler gear 19, 21 before changing again to the first and third idler gear 18, 20 in fourth gear.

[0054] For both gear changes from first to second or from third to fourth gear, the shift position within the planetary gear sets 24, 25 of range group 9 remains the same. Therefore, by releasing shift element S3 or S3' and engaging shift element S4 or S4', even under load, it is now possible to shift from first to second gear, with the electric motors 2, 3 being able to synchronize this shifting process if necessary. It is therefore very convenient to shift between gears 1, 2 or 3, 4 and to make the two related gears 1, 2 or 3, 4 powershiftable within the respective position of range group 9. For this purpose, and this is a decisive advantage over the prior art, no friction shift element is necessary; instead, shift elements S3 and S4 or S3' and S4' can be designed as positive-locking shift elements, in particular as dog-type shift elements.

[0055] By positioning the two electric motors 2, 3 on different input shafts 4, 5 and thus ultimately on different gears, virtual intermediate gears can also be enabled by having the two electric motors 2, 3 drive the output shaft 8 differently. The intermediate gears achieved in this way can particularly improve the starting performance of heavy vehicles, such as commercial vehicles. During regular operation, which is very often partial load operation, the operation of one of the two electric motors 2, 3 is then sufficient, so that the other electric motor 2, 3 and the parts of the main group 6 of the group transmission 7 connected to it do not need to be used, thus reducing wear, increasing efficiency and extending the service life of the structure. List of reference symbols 1 electric drive system 2 electric machine 3 second electric machine 4 Input shaft 5 Input shaft 6 Main group 7 group transmissions 8 Output shaft 9 Range Group 10 planetary gear set, spur gear stage 11 Sunwave 12 planet carriers 13 Output shaft, axle 14 Gear, fixed gear 15 Differential gear, gear 16 differential, differential gear 17 wheels, driven wheels 18 idler gear 19 idler gear 20 idler gear 21 idler gear 22 Fixed gear 23 Fixed gear 24 Fixed gear, planetary gear set 25 Fixed gear, planetary gear set 26 Sun 27 planetary gears, planets 28 ring gear 29 planet carrier 30 Wheel suspension S1, S1', S2, S2' switching element S1 / S2, S1' / S2' double switching element S3, S3' switching element, brake switching element S4, S4' switching element, interlocking switching element QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2008 002 380 A1

[0002] DE 10 2020 005 394 A1

[0003] WO 2023 / 031206 A1

[0004]

Claims

[1] Electric drive system (1) with at least two drive trains that are at least partially separate from one another, a first electric machine (2) and a second electric machine (3), wherein the drive trains can be individually coupled to the first or second electric machine (2, 3), wherein at least one idler gear (18 to 21) is arranged for coupling, wherein a plurality of switching elements (S1, S1'; S2, S2') are arranged for coupling at least one of the idler gears (18 to 21) to a respective input shaft (4, 5) in order to selectively transmit the drive force thereof to a respective output shaft (8), characterized by that the switching elements (S1, S1'; S2, S2') are configured to decouple the respective idler gear (18 to 21) from the input shaft (4, 5) when the electric drive system (1) is operated in partial load mode with a power requirement below a certain threshold. [2] Electric drive system (1) according to claim 1, characterized bya differential gear (16), a driven wheel (17), and a group transmission (7) with a main group (6) and a range group (9), the range group (9) having a planetary gear set (10), a first input shaft (4) of the main group (6) being coupled or capable of being coupled to the first electric machine (2) in such a way that torques originating from the first electric machine (2) can be introduced into the group transmission (7) via the first input shaft (4), a second input shaft (5) of the main group (6) being coupled or capable of being coupled to the second electric machine (3) in such a way that torques originating from the second electric machine (3) can be introduced into the group transmission (7) via the second input shaft (5), an output shaft (8) of the main group (6) being permanently coupled to a first element (26) of the planetary gear set (10) in a torque-transmitting manner,and wherein a second element (12) of the planetary gear set is permanently coupled to an output shaft (13) of the group transmission (7) in a torque-transmitting manner, wherein, with regard to a torque flow from the electric machines (2, 3) to the gear (17), the first electric machine (2), the main group (6), the range group (9), the differential gear (15) and the gear (17) are arranged one after the other in the order mentioned, wherein exactly two loose gears (18, 19), namely a first loose gear (18) and a second loose gear (19), are arranged coaxially to the first input shaft (4), wherein exactly two further loose gears (20, 21), namely a third loose gear (20) and a fourth loose gear (21), are arranged coaxially to the second input shaft (5), wherein the two input shafts (4, 5) are connected to the output shaft via exactly two fixed gears (22, 23) arranged coaxially to the output shaft (8). (8) are coupled or can be coupled, wherein a first fixed gear (22) of the fixed gears (22,23) is permanently meshed with the first and third idler gears (18, 20), and wherein a second fixed gear (23) of the fixed gears (22, 23) is permanently meshed with the second idler gear (19) and the fourth idler gear (21). [3] Electric drive system (1) according to claim 2, characterized by that a third fixed gear (24) is arranged coaxially to the output shaft (8), which permanently meshes with a fourth fixed gear (25), which in turn is connected in a rotationally fixed manner to the first element (26) of the planetary gear set (10). [4] Electric drive system (1) according to claim 2 or 3, characterized byin that in the region of each of the input shafts (4, 5) a first and a second switching element (S1, S1'; S2, S2') is provided for the first and second idler gears (18, 19) and the third and fourth idler gears (20, 21), respectively, wherein the respective first switching element (S1, S1') is designed to connect the first idler gear (18) or the third idler gear (20) to its respective input shaft (4, 5), and wherein the respective second switching element (S2, S2') is designed to connect the second idler gear (19) or the fourth idler gear (21) to its respective input shaft (4, 5). [5] Electric drive system (1) according to claim 4, characterized by that the first and second switching elements (S1, S1'; S2, S2') of the respective input shaft (4, 5) are combined to form a double switching element with a neutral position and an actuator. [6] Electric drive system (1) according to one of claims 2 to 5, characterized bythat a brake switching element (S3) is provided for braking the third element (28) of the planetary gear set (10) and / or that a blocking switching element (S4) is provided for blocking the first and third elements (26, 28) of the planetary gear set (10). [7] Electric drive system (1) according to claim 6, characterized by that the brake switching element (S3) and the blocking switching element (S4) are combined to form a double switching element with an actuator. [8] Electric drive system (1) according to one of claims 1 to 7, characterized by that a rotor of the first electrical machine (2) is connected in a rotationally fixed manner to the first input shaft (4) and a rotor of the second electrical machine (3) is connected in a rotationally fixed manner to the second input shaft (5). [9] Electric drive system (1) according to one of claims 2 to 8, characterized bythat in the planetary gear set (10) a sun (26) is formed as the first element, a planet carrier (12) as the second element and a ring gear (28) as the third element. [10] Electric drive system (1) according to one of claims 1 to 9, characterized by that the switching elements (S1, S1'; S2, S2') assigned to the respective input shafts (4, 5) are each designed as positive-locking switching elements, in particular as claw switching elements.

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