Method for operating a drive train of a work machine, drive train of a work machine, and work machine

Abstract

The invention relates to a method for operating a drive train (1) for a working machine, wherein a first electric motor (2) drives a working drive (6) of the working machine via a first transmission (4), wherein a second electric motor (3) drives a travel drive (7) of the working machine via a second transmission (5), and wherein during a shifting process of the second transmission (5) from a lower gear to a higher gear, a speed reduction of the second electric motor (3) takes place. The method according to the invention is characterized in that during the shifting process, a transmission connection is established (22) between the first electric motor (2) and the second transmission (5) via a first clutch (8), so that the first electric motor (2) drives (24, 25, 27, 28) the travel drive (7) during the shifting process. The invention further relates to a corresponding drive train (1) and a working machine.

Description

Technical Field

[0001] The invention relates to a method for operating a drive train of a working machine, a drive train of a working machine and a corresponding working machine. Background Art

[0002] In the prior art, electrically driven working machines such as wheel loaders, skid steer loaders, telescopic loaders, dump trucks or excavators are known. Such electrically driven working machines are either purely electrically driven, i.e. such electrically driven working machines have only batteries or accumulators for their energy supply. Or they are diesel-electric driven, which means that the required energy is provided by a diesel-driven generator, usually in combination with an electric buffer store, such as a capacitor of corresponding design. In all cases, the mechanical power required for the travel drive and the working drive is provided by one or more electric motors. In addition, hybrid-electric working machines are also known, in which the required mechanical power is mainly provided by an internal combustion engine, usually a diesel engine. The additionally provided electric motor usually takes on the so-called supercharging function.

[0003] Power-shiftable transmissions for working machines are also known, wherein during the shifting process a speed synchronization is achieved between the rotational speed of the drive unit and the rotational speed of the gear to be engaged. During an upshift, the rotational speed of the drive unit is correspondingly reduced, and during a downshift, it is correspondingly increased.

[0004] In this context, DE 20 2014 000 738 U1 describes a wheel loader that is driven completely by electric motors and has a first electric motor for the travel drive and a second electric motor for the working drive.

[0005] EP 0 962 597 A2 discloses a battery-operated working machine having two electric motors for the travel drive and a further electric motor for the working drive. The two electric motors for the travel drive are integrated into the front axle, each electric motor driving a wheel.

[0006] DE 10 2010 063 503 A1 also discloses a multi-speed transmission of a working machine in a planetary structure. The multi-speed transmission includes a housing containing four planetary gear sets and a plurality of shafts, and a shift element, the shift element being formed by at least one brake and a clutch, and by means of targeted actuation of the shift element, eight different transmission ratios between the drive shaft and the output shaft can be presented. The transmission of DE 10 2010 063 503 A1 can realize power shifting capability.

[0007] However, a disadvantage of known electrically driven working machines is that the speed synchronization of the gears involved in the shifting process under load, in particular in the case of a traction downshift (Zugrückschaltung), is more difficult than in the case of the same shifting process in an internal combustion engine driven working machine. The reason for this is, on the one hand, the greater moment of inertia of the electric motor compared to the internal combustion engine, but most importantly the significantly greater speed range of the electric motor, through which relatively high speed differences can also exist. This usually requires a correspondingly larger and more powerful design of the clutch in the electrically driven working machine. However, this relatively larger and more powerful design of the clutch leads to a greater structural space requirement, greater weight and greater manufacturing costs. In addition, larger clutches also have greater pulley torques and friction losses. Summary of the invention

[0008] The object of the present invention is to specify an improved method for operating a drive train of a working machine.

[0009] According to the invention, this object is achieved by a method according to the invention for operating a drive train of a working machine. Advantageous embodiments and developments of the invention are described below.

[0010] The invention relates to a method for operating a drive train of a working machine, wherein a first electric motor drives a working drive of the working machine via a first transmission, wherein a second electric motor drives a travel drive of the working machine via a second transmission, and wherein the speed of the second electric motor is increased during a shifting process of the second transmission from a higher gear to a lower gear. The method according to the invention is characterized in that during the shifting process, a transmission connection is established between the first electric motor and the travel drive via a first clutch, so that the travel drive is driven by the first electric motor during the shifting process.

[0011] During a gearshift from a higher gear to a lower gear, the second electric motor associated with the drive must increase its speed very quickly in order to establish the speed synchronization required for the gearshift between the clutch elements involved in the gearshift. According to the prior art, the speed synchronization is achieved by corresponding friction work between the clutch elements involved in the gearshift, wherein, in particular in the case of electric motors, relatively high speed differences occur, which disadvantageously must be compensated by particularly efficient and therefore heavy and expensive clutches. In addition, there is work to be applied for the speed acceleration of the second electric motor, which is relatively large due to the relatively large moment of inertia and the relatively high speed difference.

[0012] In this case, the method according to the invention is proposed: by driving the travel drive by the first electric motor, which is actually assigned to the working drive, during the shifting process of the second transmission, the second electric motor can be decoupled from the travel drive so that its entire available power can be used to the maximum extent possible to increase its own rotational speed as quickly as possible. At the same time, the first electric motor can apply the required traction force, so that no interruption of traction force occurs during the shifting process.

[0013] In the sense of the present invention, a shifting process from a higher gear to a lower gear is understood to be a shifting process from a gear with a relatively high output speed and a relatively low output torque to a gear with a relatively low output speed and a relatively high output torque.

[0014] Preferably, the speed increase of the second electric motor required for speed synchronization can be achieved in that during the gearshift process, the second electric motor is briefly disconnected from the travel drive and its speed is correspondingly increased during the disconnection from the travel drive. During the disconnection of the second electric motor, the travel drive is preferably driven by the first electric motor.

[0015] It is also conceivable and preferred to provide not only a single first or second electric motor, but also a plurality of first or second electric motors which can be coupled to each other, for example, via a summing transmission, or can each be detachably connected to the first or second transmission via a separate transmission connection.

[0016] Preferably, at least the second transmission has a plurality of gear stages configured as forward gears and at least one gear stage configured as reverse gear. Particularly preferably, the number of forward gears corresponds to the number of reverse gears. The first transmission may also have more than one gear stage configured as forward gear. Furthermore, it is also conceivable that one or more gear stages of the first transmission are configured as reverse gears. However, due to the ability of the electric motor to change its direction of rotation, it is not always necessary to provide a reverse gear.

[0017] According to a preferred embodiment of the invention, it is provided that the shifting process is carried out under load. In the sense of the invention, the term "under load" refers to the following state of the drive train: in this state, the torque is transmitted from the second electric motor or also from the first electric motor during the shifting process to the travel drive, so that the working machine, for example, obtains acceleration or performs uphill driving at a constant speed. The shifting process under load is therefore a shifting process without interruption of traction. If the disadvantageously large, expensive and heavy clutch is not used according to the prior art, the torque transmission would be interrupted during the shifting process without using the method according to the invention. In this regard, the advantages of the method according to the invention are also and primarily proven to be effective in the shifting process under load, because the shifting process can be carried out without interruption of traction and in the presence of a relatively small, low-cost and low-performance clutch. In fact, the drive train implementing the method according to the invention thus achieves the same power shifting capability without interruption of traction as a drive train provided with a relatively large, relatively heavy and relatively expensive clutch.

[0018] According to another preferred embodiment of the invention, it is provided that the first electric motor drives the travel drive and the working drive simultaneously during the gear shifting process. This results in the advantage that the working drive is not interrupted by the gear shifting process and is continuously available. The transmission connection between the first electric motor and the second transmission is established only via the first clutch, so that during the gear shifting process, in addition to the power demand of the working drive, the power demand required for the travel drive is also provided by the first electric motor.

[0019] According to another preferred embodiment of the invention, the available power of the first electric motor is used to synchronize the clutch half of the clutch associated with the lower gear stage. In this case, the clutch half associated with the drive side of the drive train is synchronized, i.e. accelerated. The acceleration of the clutch half requires considerable energy consumption, which can usually no longer be provided by the second electric motor, which must accelerate its own rotational speed.

[0020] A series of further gears or shafts (which establish the transmission connection from the first electric motor to the clutch half) are also connected to the clutch half. The series of further gears or shafts are preferably largely identical to those gears and shafts which establish the transmission connection from the second electric motor to the clutch half after the gearshift process. Advantageously, these gears and shafts have therefore also been brought to the required rotational speed by the first electric motor.

[0021] According to another preferred embodiment of the invention, the power available from the second electric motor is used to increase the speed of the second electric motor. By accelerating the clutch half by the first electric motor, the entire power available from the second electric motor can be used for its own speed adjustment, which results in an overall faster shifting process, since all the elements involved reach the required speed more quickly.

[0022] As soon as the second electric motor accelerates its speed toward the speed required for the lower gear to be engaged, the second electric motor is preferably disconnected from the travel drive and the working drive. However, if necessary, a small number of gears or shafts that cannot be transmission-disconnected from the second electric motor can still be connected to the second electric motor and thus driven or accelerated by the second electric motor.

[0023] According to another preferred embodiment of the present invention, it is provided that the first electric motor drives the travel drive only within a certain range, so as to overcome the power difference between the power demand of the travel drive and the power that can be provided by the second electric motor during the gear shift process. Therefore, this means that the mechanical power provided by the first electric motor during the gear shift process is advantageously increased precisely so that the travel drive is not subject to any power restrictions due to the gear shift process on the one hand, but is also not subject to any unsolicited power increase on the other hand. This results in the following advantage, namely that the performance of the travel drive is not affected by the gear shift process. For example, the power required by the operator of the working machine for the travel drive is provided in an unrestricted manner even during the gear shift process, for which the power provided by the first electric motor is increased to the extent that the power provided by the second electric motor is reduced due to the gear shift process. However, the total power provided to the travel drive is maintained.

[0024] According to a particularly preferred embodiment of the invention, it is provided that the first electric motor drives the travel drive only within a certain range, so that the power demand of the working drive can be fully met during the gear shifting process. This results in the advantage that it is ensured that the working drive also receives the required power requested by the operator of the working machine during the gear shifting process, so that a sudden and in particular operator-unexpected power drop of the working drive can be avoided. A power drop of the working machine that is unexpected by the operator can also lead to the occurrence of dangerous situations, for example if a lifting device of the working machine operated by the working drive no longer receives the power required to hold the lifted load. In contrast, a brief power drop in the travel drive usually does not lead to the occurrence of dangerous situations.

[0025] In the case of higher power requirements for both the travel drive and the working drive, which however can no longer be provided by the first electric motor overall, it is particularly important that the first electric motor fully meets the power requirement of the working drive. Therefore, if the total power required exceeds the maximum power that can be provided by the first electric motor, the requirement of the working drive is first fully met. Then, during the gear shifting process, the remaining, still available, surplus power of the first electric motor is provided to the travel drive.

[0026] The invention also relates to a drive train for a working machine, comprising a first electric motor and a second electric motor and a first transmission and a second transmission, wherein the first electric motor and the first transmission are assigned to a working drive of the working machine, and wherein the second electric motor and the second transmission are assigned to a travel drive of the working machine. The drive train according to the invention is characterized in that a transmission connection can be established between the first electric motor and the travel drive via a first clutch. The drive train according to the invention therefore advantageously includes all the devices and means required to be able to carry out the method according to the invention. This in turn leads to the advantages already described in conjunction with the method according to the invention.

[0027] In order to ensure the best possible execution of the method according to the invention by the drive train according to the invention, the first electric motor and the second electric motor are preferably matched to one another in terms of their available power and their torque / speed characteristic curves. This means that the maximum power that can be provided by the first electric motor advantageously varies in the range of 50% to 150%, in particular in the range of 80% to 120%, of the maximum power that can be provided by the second electric motor. Furthermore, the torque / speed characteristic curve of the first electric motor advantageously varies in the range of 50% to 150%, in particular in the range of 80% to 120%, of the torque / speed characteristic curve of the second electric motor.

[0028] It is particularly preferably provided that the first electric motor has a power that can be provided that is less than 100% of the power that can be provided by the second electric motor, but for this purpose has a higher dynamics, ie the ability to adjust the speed relatively quickly by speed acceleration or speed reduction.

[0029] Preferably, the drive train also includes its own power electronics or a separate common power electronics for controlling or regulating the speed or torque or the power to be provided by the first and second electric motors. It is also preferred that the drive train includes an electronic control unit, which controls or regulates the first and second electric motors by means of its own power electronics or by means of a common power electronics.

[0030] According to a preferred embodiment of the present invention, it is provided that the first electric motor and the second electric motor are arranged in a common housing. This enables a space-saving and weight-saving arrangement of the first electric motor and the second electric motor in a drive train in a working machine. In addition, weight and costs are saved by the common housing compared to two single housings. The first and second electric motors can, for example, be mounted axially one behind the other in a common housing, wherein the motor output shafts can, for example, extend out of the housing in opposite axial directions. Likewise, an axially side-by-side arrangement in a correspondingly constructed housing is also possible and preferred, so that the two motor output shafts can, for example, point in the same axial direction.

[0031] According to a further preferred embodiment of the invention, it is provided that the second transmission can be power-shifted in a plurality of gear steps. This results in the advantage that the power-shifting capability that can be provided by the method according to the invention is ensured not only during the shifting process from a specific lower gear step to a specific higher gear step, but also for a plurality of gear steps. As a result, the drive train according to the invention is more flexible. This results in a correspondingly adapted speed-torque characteristic and correspondingly designed performance, in particular the performance of the first electric motor.

[0032] It is particularly preferably provided that the second transmission can be power-shifted in all gear steps. This leads to a further increased flexibility of the drive train according to the invention.

[0033] It is particularly preferred that the second transmission can be shifted via three second clutches or can be power-shifted by means of the method according to the invention. In practical use, this has proven to be a good compromise between the flexibility caused by a plurality of power-shifted gear stages on the one hand and the required space requirement, weight and manufacturing costs of the drive train on the other hand.

[0034] According to a further preferred embodiment of the invention, it is provided that the working drive comprises at least one hydraulic pump, the hydraulic power of which can be set via the pivot angle. Independently of this, of course, the hydraulic power can also be set via the rotational speed of the at least one hydraulic pump and via the torque at the at least one hydraulic pump. However, due to the additional degree of freedom provided by the pivot angle for setting the hydraulic power, it is possible to set the rotational speed or torque of the first electric motor during the shifting process largely in accordance with the requirements of the travel drive, since the influence of the changed rotational speed or changed torque of the first electric motor on the at least one hydraulic pump can be compensated by correspondingly setting the pivot angle.

[0035] According to a further preferred embodiment of the invention, it is provided that the drive train is designed to carry out the method according to the invention.

[0036] It is preferably provided that the first motor or the second motor is further configured to recover kinetic energy during braking operation of the working machine. Due to the transmission connection that can be generated between the first motor and the second transmission device by the first clutch according to the present invention, kinetic energy can be advantageously recovered by the second motor and the first motor. For this purpose, the drive system also advantageously includes an electric energy storage device, to which the electric energy delivered by the recovery operation can be delivered. In the recovery operation, the first motor or the second motor works as a generator and converts mechanical energy, i.e. kinetic energy, into electric energy. If necessary, the electric energy can be taken out from the electric energy storage device again later in order to power the first motor or the second motor. In addition, it can also be provided that the electric energy storage device can be charged with external electric energy via a charging cable or other suitable charging device, such as an inductive charging device. Using the first motor or the second motor for recovery also reduces the wear of the mechanical friction brake.

[0037] The invention also relates to a working machine comprising a drive train according to the invention. The advantages already described in conjunction with the drive train according to the invention thus also result for the working machine according to the invention.

[0038] According to a preferred embodiment of the invention, it is provided that the work machine is designed as a wheel loader.

[0039] Alternatively, the work machine can preferably also be designed as a dump truck, an excavator, a telescopic loader or a tractor. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The present invention is exemplarily described below based on the embodiments shown in the accompanying drawings.

[0041] Figure 1 By way of example and schematically, a possible embodiment of a drive train according to the invention of a working machine is shown.

[0042] Figure 2 A further possible embodiment of the drive train 1 according to the invention of a working machine is shown by way of example in the form of a block diagram in the form of a gear diagram.

[0043] Figure 3 A possible embodiment of the method according to the invention for operating a drive train of a work machine is shown by way of example and schematically in the form of a flow chart.

[0044] The same objects, functional units and similar components are denoted by the same reference numerals in the drawings. These objects, functional units and similar components are implemented identically in terms of their technical features, unless otherwise indicated explicitly or implicitly in this description. DETAILED DESCRIPTION

[0045] Figure 1 The block diagram schematically shows the Figure 1 1 is a possible embodiment of the drive train 1 according to the invention of a working machine not shown in the figure. The drive train 1 shown by way of example comprises a first motor 2 and a second motor 3 as well as a first transmission 4 and a second transmission 5, 5'. According to the example, the first motor 2 and the second motor 3 are arranged in a common housing 11. According to the example, the second transmission 5, 5' is composed of a transmission stage 5 upstream of the transmission and a multi-stage, power-shiftable transmission 5'. The first motor 2 and the first transmission 4 are assigned to the working drive 6 of the drive train 1, wherein, according to the example, the working drive 6 also has an ePTO interface 12 (electric power output interface). Conversely, the second motor 3 and the second transmission 5 are assigned to the travel drive 7 of the drive train 1, wherein the travel drive 7 also includes an output shaft 13. In addition, a transmission connection can be established between the first motor 2 and the travel drive 7 via a first clutch 8, wherein, according to the example, the transmission connection specifically extends from the first motor 2 to a position between the transmission stage 5 and the power-shiftable transmission 5'. This drive connection advantageously enables the travel drive 7 to be driven by the first electric motor 2 (which is actually associated with the working drive 6) during the shifting process of the second transmission 5. The second electric motor 3 can thus be decoupled from the travel drive 7 and a speed synchronization in the sense of an increase in the speed of the second electric motor 3 can be set or adjusted without a loss of traction in the travel drive 7. At the same time, the first electric motor can already synchronize or accelerate the clutch halves and the gears and shafts connected to the clutch halves. Accordingly, in the embodiment of the method according to the invention, it is not necessary to achieve speed synchronization by friction work, so that the corresponding clutch of the second transmission 5 can be designed to be smaller and more cost-effective than is common in the prior art.

[0046] Figure 2 The gear diagram is shown as an example. Figure 2 A further possible embodiment of the drive train 1 according to the invention of a working machine not shown in FIG. Figure 2 The drive train 1 comprises a first electric motor 2 and a second electric motor 3 which are arranged in a common housing 9. In addition, Figure 2The drive train 1 comprises a first transmission 4 and a second transmission 5, wherein the first electric motor 2 and the first transmission 4 are assigned to a working drive 6 of the drive train 1. The second electric motor 3 and the second transmission 5 are assigned to a travel drive 7 of the drive train 1. A drive connection can be established between the first electric motor 2 and the second transmission 5 by means of a first clutch 8, wherein, according to the example, a drive connection can be established from the first electric motor 2 to the shaft 14 of the second transmission 5. Thus, when the first clutch 8 is closed, the first electric motor 2 can drive the travel drive 7. According to the example, the second transmission 5 also comprises, for example, three second clutches 9, 9' and 9", and three shiftable gear stages of the second transmission 5 are provided by means of three different spur gear stages 10, 10', 10".

[0047] Figure 3A possible embodiment of the method for operating a drive train 1 of a working machine according to the invention is shown by way of example and schematically in the form of a flow chart. The first electric motor 2 of the drive train 1 drives a working drive 6 of the working machine via a first transmission 4, and the second electric motor 3 of the drive train 1 drives a travel drive 7 of the working machine via a second transmission 5. In method step 20, a shifting process from a higher gear of the second transmission 5 to a lower gear is initiated by the operator of the working machine. The initiation of the shifting process is carried out by actuating a corresponding shifting element of the working machine, in the example by a gear selector lever. In method step 21, a control device checks whether the first electric motor 2 assigned to the working drive 6 of the working machine 1 has sufficient power reserve to support the shifting process in addition to driving the working drive 6. This is the case, for example, because the working drive 6 is not currently driven. Therefore, in the following method step 22, a transmission connection is established between the first electric motor 2 and the travel drive 5, which is achieved by closing the first clutch 8. In step 23, the first clutch 8 is completely closed, and the first electric motor 2 and the second electric motor 3 transmit power to the travel drive 7, that is, drive the travel drive 7. In method step 24, the second electric motor 3 reduces the power it transmits to the travel drive 7, wherein at the same time, the first electric motor 2 increases the power it transmits to the travel drive 7. The increase in power transmitted by the first electric motor 2 corresponds exactly to the reduction in power transmitted by the second electric motor 3, thereby overcoming the power difference between the power requirement of the travel drive 7 and the power that can be provided by the second electric motor 3 during the shifting process. In the subsequent method step 25, the power transmitted by the second electric motor 3 to the travel drive 7 is reduced to zero by opening the corresponding clutch. At the same time, the first electric motor 2 further increases the power transmitted to the travel drive 7. The travel drive 7 is now driven only by the first electric motor 2. In step 26, the second electric motor 3 now starts the speed synchronization in the sense of the speed increase. According to the example, the speed increase is carried out in such a way that the maximum current is supplied to the second electric motor 3. As soon as the necessary speed increase is completed and the speed synchronization is reached, the clutch 9' of the second transmission 5, which is also involved in the shifting process, is closed. Thus, a transmission connection is established again between the second electric motor 3 and the travel drive 7. In method step 27, the first electric motor 2 reduces the power it transmits to the travel drive 7, while the second electric motor 3 increases the power it transmits to the travel drive 7 to the same extent. In this case, the reduction in power transmitted by the first electric motor 2 corresponds exactly to the increase in power transmitted by the second electric motor 3. The travel drive 7 thus receives a constant power supply. Finally, in method step 28, the first electric motor 2 no longer transmits any power to the travel drive 7. The travel drive 7 is again driven only by the second electric motor 3.The first clutch 8 is opened and thus the transmission connection between the first electric motor 2 and the second transmission 5 or the travel drive 7 is interrupted. The shifting process is thus completed. Since power is transmitted from the first electric motor 2 or the second electric motor 3 to the second transmission 5 or the travel drive 7 during the entire shifting process, the shifting process is carried out under load. The drive train 1 is thus power-shiftable.

[0048] Reference numerals list

[0049] 1 Drive system

[0050] 2 First motor

[0051] 3 Second motor

[0052] 4 First transmission

[0053] 5 Second transmission

[0054] 6 Job Driver

[0055] 7 Travel drive

[0056] 8 First Clutch

[0057] 9, 9', 9" Second clutch

[0058] 10, 10', 10" cylindrical gear stage

[0059] 11 Common Shell

[0060] 12 ePTO

[0061] 13 Output shaft

[0062] 14 Axis

[0063] 20 Importing the gear shift process

[0064] 21 Check power reserve

[0065] 22 Establishing the drive connection

[0066] 23 Fully close the first clutch

[0067] 24 Reduce the power of the second motor and increase the power of the first motor.

[0068] Machine power

[0069] 25 Further reduce the power of the second motor, further

[0070] Increase the power of the first motor

[0071] 26 Speed ​​synchronization of the second motor

[0072] 27 Reduce the power of the first motor and increase the power of the second motor.

[0073] Machine power

[0074] 28 Further reduce the power of the second motor, further

[0075] Increase the power of the first motor

Claims

1. A method for operating a drive train (1) of a working machine, in, The first motor (2) drives the working drive (6) of the working machine via the first transmission device (4). The second electric motor (3) drives the travel drive (7) of the working machine via a second transmission device (5), and wherein the speed of the second electric motor (3) is increased during a shifting process of the second transmission (5) from a higher gear stage to a lower gear stage, It is characterized in that During the shifting process, a transmission connection is established between the first electric motor (2) and the driving drive (7) via a first clutch (8), so that the driving drive (7) is driven by the first electric motor (2) during the shifting process, wherein the first electric motor (2) drives the driving drive (7) only within a certain range, so that a power difference between a power requirement of the driving drive (7) and a power that can be provided by the second electric motor (3) during the shifting process is overcome.

2. The method according to claim 1, It is characterized in that The shifting process is carried out under load.

3. The method according to claim 1, It is characterized in that The first electric motor (2) drives (24, 25, 27, 28) the travel drive (7) and the working drive (6) simultaneously during a gear shifting process.

4. The method according to any one of claims 1 to 3, It is characterized in that The power available from the first electric motor (2) is used to synchronize the clutch halves of the clutch (9, 9', 9") assigned to the lower gear stage.

5. The method according to any one of claims 1 to 3, It is characterized in that The power that the second electric motor (3) can provide is used to increase the rotation speed of the second electric motor (3).

6. The method according to any one of claims 1 to 3, It is characterized in that The first electric motor (2) drives the travel drive (7) only within a certain range, so that the power requirement of the working drive (6) can be fully met during the gear shifting process.

7. A drive system (1) for a working machine, the drive system comprising a first motor (2) and a second motor (3) and a first transmission device (4) and a second transmission device (5), in, The first electric motor (2) and the first transmission (4) are assigned to a working drive (6) of the working machine, and The second electric motor (3) and the second transmission (5) are associated with a travel drive (7) of the working machine. It is characterized in that A transmission connection can be established between the first electric motor (2) and the travel drive (7) via a first clutch (8), wherein the speed of the second electric motor (3) is increased during a shifting process of the second transmission (5) from a higher gear to a lower gear, and during the shifting process, a transmission connection is established between the first electric motor (2) and the travel drive (7) via the first clutch (8), so that the travel drive (7) is driven by the first electric motor (2) during the shifting process, and wherein the first electric motor (2) drives the travel drive (7) only within a certain range, so that a power difference between a power requirement of the travel drive (7) and a power that can be provided by the second electric motor (3) during the shifting process is overcome.

8. The drive train (1) according to claim 7, It is characterized in that The first electric motor (2) and the second electric motor (3) are arranged in a common housing (11).

9. The drive train (1) according to claim 7, It is characterized in that The second transmission device (5) can perform power shifting in multiple gear stages.

10. Drive train (1) according to any one of claims 7 to 9, It is characterized in that The working drive (6) comprises at least one hydraulic pump (12), the hydraulic power of which can be set via the pivot angle.

11. Drive train (1) according to any one of claims 7 to 9, It is characterized in that The drive train (1) is designed to carry out the method according to any one of claims 1 to 6.

12. A working machine comprising a drive train (1) according to any one of claims 7 to 11.

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