Method for operating a drive train, drive train and working machine

Abstract

The invention relates to a method for operating a drive train of a machine, wherein the drive train comprises at least one first electric machine (60) with a first motor shaft (62) for driving a first axle arrangement (12). The method includes a step of detecting (600) an impending overspeed in the first electric machine (60). Furthermore, the method includes a step of activating (602) a protective measure for the first electric machine (60) in response to the impending overspeed. The invention also relates to a drive train and a machine.

Description

[0001] The present invention relates to a method for operating a drive train of a working machine. Furthermore, the invention relates to a drive train and a working machine. State of the art

[0002] A machine's drivetrain can provide both driving power at an output shaft and working power, for example, at a power take-off (PTO) shaft. Electrification can often significantly reduce the complexity of the drivetrain. Furthermore, it can considerably lower the environmental impact of operating the machine. Therefore, many conventionally powered machines are being retrofitted with an electrified drivetrain.

[0003] In electrified powertrains, the gear ratio spread is usually smaller than in internal combustion engines, since an electric motor can often operate efficiently across a wider speed range. Therefore, the transmission in electrified powertrains often lacks adjustable gear ratios or has only a few gears. This can, however, lead to excessively high speeds in the electric motor during deceleration. Description of the invention

[0004] A first aspect concerns a method for operating the drivetrain of a machine. The drivetrain can, for example, be designed to provide propulsion power for driving the machine. Alternatively or additionally, the drivetrain can optionally also provide work power, for example, for moving or otherwise operating the machine's various tools. The work power can be provided, for example, as mechanical work power at one or more power take-off shafts (PTOs). The work power can also be provided, for example, as hydraulic work power. The propulsion power can be provided, for example, at one or more driven axles. The machine can be, for example, an agricultural machine or a construction machine. An example of an agricultural machine is a tractor. An example of a construction machine is a wheel loader.The machine can be designed as a tractor. For example, a trailer can be coupled to the machine for pulling. The attachment can also be designed as a trailer.

[0005] The drive train comprises a first electric machine with a first motor shaft for driving a first axle assembly. The first electric machine can be a traction motor of the driven machine. An electric machine can be, for example, a synchronous motor or an asynchronous motor. The electric machine can, for example, convert electrical energy into mechanical energy. The electric machine can, for example, have only a motor shaft, which is set in rotation during operation. The electric machine can also be designed for recuperation. The drive train can include the first axle assembly. An axle assembly can include the first electric machine as a drive motor and an output shaft, which drives the driven machine. The drive train can include a first power take-off (PTO) drive.A power take-off (PTO) drive can consist of a drive motor and a power take-off shaft, which allows an implement to be driven. The drive train can then supply power to the implement.

[0006] The process includes a step for detecting an impending overspeed of the first electric motor. This overspeed detection can occur, for example, when the speed of the first electric motor exceeds a certain threshold, or optionally, when the acceleration also exceeds a certain threshold. The speed threshold can also be determined based on the acceleration. The overspeed can be a speed at which excessive wear or damage, such as motor failure, could occur.

[0007] Detection can be achieved, for example, using a detection device equipped with appropriate sensors. Detection can be analytical or performed using a machine learning model, which could, for instance, be a previously trained neural network. Overspeed can also be a limit set during testing or generally defined for other technical reasons. The threat of overspeed can mean that a certain speed will be exceeded with a minimum probability. Alternatively or additionally, the threat of overspeed can mean that the specified speed will be exceeded without any change in the driving conditions or intervention. Overspeed can be a threat, for example, when the machine is in a deceleration state. This can occur, for instance, when descending a slope.The likelihood of overspeeding increases, for example, with a trailer and, alternatively or additionally, a heavy load. Unlike an internal combustion engine, an electric motor can have a slight natural braking effect when de-energized. Furthermore, the drivetrain typically lacks a gearbox and instead uses a transmission with a fixed speed ratio, which may optionally include a differential function. Due to speed and torque requirements, as well as space constraints, the drivetrain is usually designed so that the usable speed range of the electric motor and the transmission ratio are just sufficient to meet these requirements and avoid operating the electric motor at excessively high speeds.

[0008] The method includes a step of activating a protective measure for the first electric motor in response to an impending overspeed. This prevents overspeed without limiting the performance of the drivetrain or requiring a different drivetrain design for potentially high-speed operating scenarios. The protective measure can, for example, include appropriate drivetrain control that prevents the first electric motor from accelerating and exceeding the overspeed limit. Activation of the protective measure can be performed by a control device. This control device can, for example, include an inverter that supplies power to the first electric motor. The control device can also be configured to control a service brake and / or the respective clutches.Optionally, additional control interventions can be made in response to the activation of the protective measure to stabilize the machine's movement. For example, steering interventions and, alternatively or additionally, braking of individual wheels can be performed to prevent a trailer pulled by the machine from skidding.

[0009] If the drive train includes additional electric motors, such as a power take-off (PTO) motor or a second electric motor for driving an axle assembly, these motors can also be equipped to detect an associated impending overspeed. For example, an implement can also cause a thrust condition on a PTO shaft or another electric motor configured as a traction motor. For each of these electric motors, a corresponding protective measure can then be implemented in response to the detection of its impending overspeed. The possible protective measures and detection methods for impending overspeed described here can also be used for these electric motors, where applicable.

[0010] In one embodiment of the method, the protective measure may include operating the first electric machine in a generator mode. In generator mode, an energy storage device can be charged. Regenerative braking is also possible in generator mode. This allows the first electric machine to cause a deceleration, thereby reducing the probability of exceeding the overspeed limit and simultaneously generating energy. Generator mode can also be activated if an overspeed is imminent, even if it was previously deactivated for other reasons.

[0011] In one embodiment of the method, the state of charge of an energy storage device in the drivetrain can be monitored when the first electric machine is operated in generator mode. This can be done, for example, by a monitoring device. The monitoring device can, for example, include a battery management system. From a certain state of charge, at least some of the electrical power generated by the generator mode can be dissipated as heat. For example, all the generated electrical power can be dissipated as heat. This allows the braking effect to be achieved by operating the electric machine in generator mode, even when the energy storage device is fully charged. For example, a brake chopper can be activated for this purpose.

[0012] In one embodiment of the method, the protective measure may include the application of a service brake to the drive train. The service brake can be applied, for example, only if the regenerative operation of the first electric machine is insufficient to prevent reaching or exceeding the overspeed limit. For instance, the service brake is applied when a thermal limit is reached in the brake chopper. Applying the service brake reliably prevents exceeding the overspeed limit.

[0013] In one embodiment of the method, the protective measure may involve opening an operative connection between the first electric machine and an output element of the first axle assembly. The output element may be, for example, a wheel, a chain, a differential, or generally an output shaft. The first electric machine can be decoupled. For example, a switching element may be opened or a gearbox may be switched to neutral. This terminates the thrust state of the first electric machine, reliably preventing overspeed. The operative connection is opened, for example, only if the regenerative operating mode and, alternatively or additionally, the service brake alone cannot prevent reaching or exceeding the overspeed.

[0014] In one embodiment of the method, the detection of impending overspeed can be based on at least one speed parameter. This speed can be the travel speed of the machine. Alternatively or additionally, the detection of impending overspeed can be based on an acceleration parameter. The acceleration can be the vehicle's acceleration or the acceleration of the first motor shaft. By considering the acceleration, exceeding the overspeed can be reliably predicted without protective measures. Alternatively or additionally, the detection of impending overspeed can be based on a derivative of the acceleration parameter. This derivative of the acceleration can be a jerk.By considering the derivative of acceleration, exceeding the overspeed limit without protective measures can be reliably predicted, for example, in conjunction with acceleration and speed as key parameters. Alternatively or additionally, the detection of impending overspeed can be based on a planned route as a key parameter. In this case, the key parameter can be complex information and not just a single value. Based on the planned route, accelerations of the machine and thus also of the first electric motor can be predicted, for example, due to a gradient along a section of the route. Alternatively or additionally, the detection of impending overspeed can be based on a load condition as a key parameter. The load condition can be the total vehicle weight. The load condition can also include the weight of a trailer and, alternatively or additionally, attachments.The load condition can reveal how effective a deceleration is and what forces are necessary to prevent overspeed. This allows for particularly accurate prediction of an impending overspeed and enables appropriate and timely activation of protective measures.

[0015] In one embodiment of the method, the impending overspeed can be detected when a speed threshold is exceeded. This speed threshold can be fixed or determined based on the previously described parameters. This allows for either simple or demand-based variable activation of the protective measure.

[0016] In one embodiment of the method, the impending overspeed can be detected by a prediction. This allows the protective measure to be taken particularly early, and even if the vehicle's condition changes, for example due to an increasing gradient, overspeed can still be reliably avoided.

[0017] In one embodiment of the method, the impending overspeed can be detected using a machine learning model. This model could, for example, be a previously trained artificial neural network. The parameters described above can be used as input data. A predicted rotational speed can be output as output data. The training data can be generated experimentally or artificially. The machine learning model can also operate using reinforced learning, thus eliminating the need for complex training.

[0018] A second aspect concerns a drive train. The drive train can be operated using the method described in the first aspect. The respective advantages and further features are detailed in the description of the first aspect, whereby embodiments of the first aspect also constitute embodiments of the second aspect and vice versa. The drive train comprises at least one first electric machine with a first motor shaft for driving a first axle assembly. The drive train includes a detection device designed to detect an impending overspeed in the first electric machine. Furthermore, the drive train includes a control device designed to activate a protective measure for the first electric machine in response to its impending overspeed.

[0019] The first axle assembly can include, in addition to the first electric motor with the first motor shaft, a first differential, a first output shaft, a second output shaft, a first output element, and a second output element. A differential can be configured to convert an input variable into an output variable. For example, the differential can convert speed to low or high. The differential can optionally be configured to provide different gear ratios. The differential can be configured to provide a differential function. The differential can have one input shaft and two output shafts. The output shafts can rotate at different speeds, for example, depending on a torque applied to the output shafts. The differential can transmit motor power from the first motor shaft to the two output shafts.The first and second output shafts can each form an output shaft or be rotationally fixed to it. An output element can be a component by which the drive train transmits drive power to a surface on which the machine stands. For example, output elements can be designed as wheels or as pinions to drive a track. The first and second output elements can be located on opposite sides of the machine. For example, the first output element can be a left wheel and the second output element a right wheel of a driven axle of the machine.

[0020] The first power take-off (PTO) drive can comprise a first PTO electric motor with a first PTO motor shaft and a first power take-off (PTO) shaft. The designation "PTO electric motor" can serve for identification purposes. The PTO electric motor can be designed like other electric motors. The PTO electric motor can be designed for lower power output than the first electric motor. The designation "PTO motor shaft" can also serve for identification purposes. The PTO motor shaft can be a motor shaft of a PTO electric motor. The PTO shaft can be a shaft at which power can be supplied externally by the machine. For example, the PTO shaft can protrude from the front or rear of the machine. The PTO shaft can be designed for connecting and driving an implement. The first PTO shaft can, for example, be located adjacent to the first axle assembly, in particular its first output shaft and its second output shaft.For example, the first axle assembly, with its first and second output shafts, can form a driven rear or front axle of the machine. Similarly, the first power take-off (PTO) shaft can form a rear or front PTO shaft of the machine. The first PTO generator can be positioned, for example, in front of or behind the first axle assembly in the longitudinal direction of the vehicle.

[0021] The first motor shaft can be mechanically connected to the first and second output shafts via the differential. This allows drive power from the first motor shaft to be distributed between the two output shafts via the differential. The first motor shaft can be arranged coaxially with the first output shaft and, alternatively or additionally, with the second output shaft. The first and second output shafts can be arranged coaxially with each other. The two output shafts can, for example, extend transversely across the vehicle. The first electric motor can thus form a coaxial axle drive, making the drive arrangement particularly compact and easy to integrate into the vehicle. The first output shaft can be mechanically connected to the first output element.This allows for a compact transmission of drive power to the ground and optionally provides an additional gear ratio in the connection between the first output shaft and the first output element. The first output shaft and the first output element can be arranged coaxially. The second output shaft can be mechanically connected to the second output element. This allows for a compact transmission of drive power to the ground and optionally provides an additional gear ratio in the connection between the second output shaft and the second output element. The second output shaft and the second output element can be arranged coaxially.

[0022] The first differential gear can include a first differential lock, a first planetary gear set with a first sun gear, a first planet carrier, and a first ring gear, and a second planetary gear set with a second sun gear, a second planet carrier, and a second ring gear. The planetary gear set can be designed compactly with few components to provide both a transmission from the first electric motor to the output of the driven machine and the differential function. The first differential lock can be configured to connect the two output shafts of the differential gear in a rotationally fixed manner. This allows for the integration of the differential lock with minimal effort. The first differential lock can, for example, be designed as a switching element by means of which the first and second output elements can be connected in a rotationally fixed manner. The first ring gear is permanently and rotationally fixed to the second sun gear.The two planetary gear sets can be stacked radially. The second planetary gear set can, for example, extend in the same axial range as the first planetary gear set. For instance, all rotating elements of the second planetary gear set can be arranged radially outside the first planetary gear set. This results in a very compact axial design, allowing the differential and the first electric motor to be arranged coaxially side-by-side in the longitudinal direction of the vehicle within the driven machine. The first ring gear and the second sun gear can, for example, be formed as a single piece. An internal toothing can form the first ring gear section, and an external toothing the second sun gear section. Each planetary gear set can, for example, have only one sun gear, one planet carrier, and one ring gear. For instance, the second planetary gear set can have only a single sun gear.The first motor shaft can, for example, be permanently and rotationally fixed to the input shaft of the differential gear.

[0023] The numbering of rotating elements can serve to assign them to a planetary gear set. For example, designating it as the second sun gear can uniquely identify it as belonging to the second planetary gear set. Generally, the numbering, and alternatively or additionally, the designation of components according to their assembly group, can serve this purpose.

[0024] The first PTO motor shaft can be mechanically connected to the first power take-off (PTO) shaft. For example, the first PTO motor shaft can be mechanically connected to the first PTO shaft via a spur gear stage and, alternatively or additionally, a bevel gear stage. The first PTO motor shaft can be connected to the first PTO shaft, for example, via a first PTO switching element. The first PTO switching element can be located, for example, in the longitudinal direction of the vehicle in front of or behind the first axle assembly. The first PTO switching element can be located, for example, in the longitudinal direction of the vehicle relative to the first axle assembly, and alternatively or additionally, the first motor shaft can be located on the side of the PTO motor or on the side of the PTO shaft. The first PTO switching element can be designed as a conventional switching element, for example, as a friction-fit or positive-locking coupling.The first PTO engine shaft and the first power take-off (PTO) shaft can be connected via a first PTO gearbox. The PTO gearbox can, for example, be designed to provide two gears for this connection. A connection between the first PTO engine shaft and the first PTO shaft can be referred to as the first PTO functional connection. For example, the first PTO functional connection can include shafts for torque transmission. The first PTO functional connection can be designed to transmit torque from the first PTO engine shaft to the first PTO shaft. The PTO engine shaft can, for example, extend transversely (e.g., orthogonally) or parallel to the first output shaft, the second output shaft, and alternatively or additionally to the first engine shaft.

[0025] The first power take-off (PTO) connection from the first PTO motor shaft to the first PTO shaft extends, for example, transversely to the first output shaft and, alternatively or additionally, transversely to the second output shaft between the first electric motor and the differential gear in an axial direction of the first output shaft. This arrangement allows the differential gear and the first electric motor to be well integrated into the machine, and the first PTO shaft to be located at an easily accessible point within the machine. For example, at least one connecting shaft of the first PTO connection extends orthogonally to the first output shaft and, alternatively or additionally, to the first motor shaft. This connecting shaft can, for example, extend in the longitudinal direction of the machine.The connecting shaft can, for example, extend centrally within the machine in the transverse direction of the vehicle, which may correspond to the axial direction of the first output shaft. For instance, the first differential gear can be located to the left of the connecting shaft and the first electric motor to the right. The first pivot connection, for example, intersects the first output shaft, the second output shaft, and, alternatively or additionally, a connection from the first motor shaft to the first differential gear in a top view of the machine. For example, the first pivot connection may be routed below the output shaft, passing alongside it. Due to the typically large diameters of output elements in machine tools, sufficient installation space and ground clearance can be ensured, resulting in a compact design.The axial extent of the first electric motor can be defined by its rotor and, alternatively or additionally, its stator. The first rotor and, alternatively or additionally, the first stator can be arranged transversely to the vehicle or along an axial extent of the output shaft on one side of the first power take-off connection, and the differential gear can be arranged on the opposite side of the power take-off connection, transversely to the vehicle or along an axial extent of the two output shafts. The first differential lock can, for example, be arranged on the side of the differential gear facing away from the first electric motor.

[0026] The second PTO motor shaft can be mechanically connected to a pump device. This pump device can, for example, supply pressure to the hydraulic system of the machine. The PTO motor can also drive the pump device, thus providing pressure to the hydraulic system. The drive train can also include additional electric motors to drive further pump devices. These additional pump devices can, for example, supply pressure to a steering system, hydraulic switching elements, and, alternatively or additionally, to transmission lubrication. The hydraulic system can also be supplied with pressure by a separate electric motor.

[0027] The first output shaft can be operatively connected to the first output element, for example, via a planetary gear set or a spur gear stage. This allows for a further gear ratio to be provided there. Similarly, the second output shaft can be operatively connected to the second output element via a planetary gear set or a spur gear stage. For example, such a planetary gear set can be arranged within the associated output element.

[0028] A rotationally fixed connection between two elements is understood to be a connection in which the two elements are essentially rigidly coupled to each other in all intended states. This also includes a friction-fit connection, in which intentional or unintentional slippage can occur. Permanently rotationally fixed elements can, for example, exist as permanently rotationally fixed individual components or as a single piece.

[0029] A connection between two elements via another element can mean that this additional element is involved in an indirect functional connection between the two elements. For example, this element can be positioned in the force flow between these two elements. A connection between two elements via two or more elements can mean that these additional elements are all involved in an indirect functional connection between the two elements. A switchable connection can, in one state, enable torque transmission between two elements, for example, through a rigid coupling, and, in another state, essentially interrupt this torque transmission. A corresponding switching element can be provided between the two elements for this purpose. If two elements can be connected in a rotationally fixed manner, these two elements can, for example, be connected to each other in a rotationally fixed manner via a switching element.If two elements can be mechanically connected, these two elements can, for example, be connected via a switching element for torque transmission.

[0030] A planetary gear set is configured, for example, as a negative planetary gear set or a positive planetary gear set. The sun gears, planet carriers, and ring gears of a planetary gear set constitute its rotating elements. Each planetary gear set can have one or more planet gears, which are rotatably mounted on the planet carrier. For example, the planet gears of a planetary gear set mesh with a sun gear and a ring gear of the same planetary gear set. Each planetary gear set can be free of elements other than those mentioned here. A rotational axis of a planetary gear set can correspond to a rotational axis of its rotating elements.

[0031] In one embodiment of the drivetrain, the drivetrain may include an all-wheel-drive switching element and a second axle assembly. The first motor shaft can be mechanically connected to the second axle assembly via the all-wheel-drive switching element. This allows a second axle, with, for example, two output elements, to be driven by the first electric motor. This enables the provision of all-wheel drive with minimal effort. An all-wheel-drive connection from the first motor shaft to the second output shaft can be established between the first electric motor and the differential gear in an axial direction of either the first or second output shaft.For example, a spur gear or bevel gear of the all-wheel drive connection can be arranged axially along the first output shaft between the first electric motor and the differential, either on the first or second output shaft. The all-wheel drive connection can include, for example, connecting shafts, spur gear stages, bevel gear stages, and, alternatively or additionally, the all-wheel drive shift element, for instance, to transmit torque from the first axle assembly to the second axle assembly. The all-wheel drive connection can be provided as an alternative to, or in addition to, the first PTO connection. Due to the typically large diameters of output elements in agricultural machinery, sufficient installation space and ground clearance can be ensured, resulting in a compact design.

[0032] In one embodiment of the drivetrain, the all-wheel drive connection may include a bevel gear stage and a spur gear stage. This allows for a simple transverse connection. A bevel gear stage can, for example, connect two shafts at an angle of 90° to each other.

[0033] A first bevel gear in the bevel gear stage can be permanently and rotationally fixed to the first motor shaft. A second bevel gear in the bevel gear stage can be permanently and rotationally fixed to a spur gear in the spur gear stage. The design of the connection can be simple. For example, the spur gear stage can pass below the first output shaft.

[0034] Alternatively, the first spur gear of the spur gear stage can be permanently and rotationally fixed to the first motor shaft. A second spur gear of the spur gear stage can be permanently and rotationally fixed to a bevel gear of the bevel gear stage. This design allows for a reduced operating speed at the bevel gear drive. It can also simplify assembly, for example, via journals on the second planet carrier. Furthermore, manufacturing the teeth of the first spur gear can be simpler, as the diameter can be smaller. The bevel gear stage, another spur gear stage, or a shaft can, for example, pass below the first output shaft.

[0035] In one embodiment of the drive train, the second axle assembly may comprise at least one of the following components, which may be designed in the same way as in the first axle assembly. For example, the second axle assembly may comprise a second electric motor with a second motor shaft, constructed and connected in the same way as the first electric motor. For example, the second axle assembly may comprise a second differential gear, constructed and connected in the same way as the first differential gear. For example, the second axle assembly may comprise a third output shaft, which has an axial length like the first output shaft. For example, the second axle assembly may comprise a fourth output shaft, which has an axial length like the second output shaft.For example, the axial length of both axle assemblies can be the same and can be selected modularly by choosing the two associated output shafts. The second axle assembly can have a similar or identical design to the first axle assembly. The aforementioned components can be modularly modifiable, for example, to adapt the track width and power output to different machine applications. For example, the second axle assembly can also include a second drive shaft, which can be designed and positioned like the first drive shaft in relation to the second axle assembly. The second drive shaft can be located at an end of the machine opposite the first drive shaft. The second drive shaft can be constructed and operatively connected like the first drive shaft.The second dispensing drive can have a second dispensing electric motor and a second power take-off shaft, which can be driven by the second dispensing electric motor.

[0036] The second axle arrangement can be similar to or identical to the first axle arrangement, but without, for example, an electric motor. The second axle arrangement can include a third output shaft, a fourth output shaft, and a second differential. These components can be designed like those of the first axle arrangement, allowing for the use of many identical parts. The first motor shaft can be mechanically connected to the third and fourth output shafts via the second differential using the all-wheel-drive shift element. The first motor shaft can also be mechanically connected or operatively coupled to an input shaft of the second differential. In a operatively coupled configuration, the all-wheel-drive shift element can be omitted, providing permanent all-wheel drive.

[0037] Alternatively, the second axle assembly features a second electric motor. This second electric motor can be designed like the first. For example, the same axle assembly can be modularly installed multiple times in the machine. For instance, a second motor shaft of the second electric motor is mechanically connected to the input shaft of the second differential. This allows for cost-effective provision of high drive power. The all-wheel drive connection can then be omitted. However, the all-wheel drive connection can still be provided for combined braking of both axle assemblies.

[0038] In one embodiment of the drivetrain, the all-wheel drive connection may pass the first output shaft and, alternatively or additionally, the second output shaft below the first output shaft. "Below" can be defined by the vehicle's vertical direction. Alternatively or additionally, the all-wheel drive connection may pass the first power take-off connection below the first power take-off connection.

[0039] In one embodiment of the drive train, the first axle assembly may have a modular design in which at least one of the following components is modularly interchangeable for adaptation to the driven machine. For each modularly interchangeable component, there may be, for example, at least two variants. The first output shaft and, alternatively or additionally, the second output shaft may be interchangeable, for example, to adapt to a different track width. The variants may therefore be of different lengths. The connection from the first output shaft to the first output element and, alternatively or additionally, the connection from the second output shaft to the second output element may be interchangeable. This allows for different gear ratios to be provided for adaptation to a different speed range of the driven machine. Furthermore, the connection may be steered or unsteered.This allows for the provision of a steered or unsteered axle. The first differential gear can be modularly interchangeable, for example, for different gear ratios. Similarly, the second axle assembly can have a modular design, with equivalent components that are modularly interchangeable to adapt to the machine being driven.

[0040] In one embodiment of the drivetrain, the first sun gear may be permanently and non-rotatably connected to the first motor shaft. The first sun gear may, for example, form the input shaft of the first differential. The first planet carrier may be permanently and non-rotatably connected to the first output shaft. The first planet carrier may, for example, form the first output shaft of the planetary gear set. The second planet carrier may be fixed to a stationary component, such as a vehicle frame or a transmission housing. The second ring gear may be permanently and non-rotatably connected to the second output shaft. The second ring gear may, for example, form the second output shaft of the planetary gear set.By selecting the appropriate gear ratio, it is easy to provide the same ratio for both output shafts of the differential, provided, for example, the machine is traveling straight ahead and both output shafts have the same slip. Furthermore, this allows for the easy integration of the first differential lock.

[0041] In one embodiment of the drive train, the differential lock may be designed to connect the first planet carrier to the second ring gear in a rotationally fixed manner.

[0042] In one embodiment of the drivetrain, the drivetrain may have a first service brake designed to brake the first output element. Alternatively or additionally, the drivetrain may have a second service brake designed to brake the second output element. This allows the output elements to be braked individually, enabling additional functions. For example, the two service brakes may be designed as disc brakes or drum brakes on the wheels. Similarly, a third service brake and a fourth service brake may be provided in the second axle arrangement, designed analogously to the first and second service brakes.

[0043] In one embodiment of the drivetrain, a central service brake may be provided, which is designed to brake the all-wheel drive connection between the first axle arrangement and the second axle arrangement. This allows all axles to be braked centrally together. This frees up more installation space between the output elements for other components. When the central service brake is applied, the all-wheel drive shift element can, for example, be automatically closed. The all-wheel drive shift element can also be automatically closed when the brakes are applied to individual service brakes at the output elements.

[0044] The powertrain can include an energy storage device for supplying power to the respective electric motors. The energy storage device can be located, for example, centrally in the vehicle's longitudinal direction. It can also be located, for example, in front of the first axle assembly in the vehicle's longitudinal direction. Finally, it can be located, for example, between the first and second axle assemblies in the vehicle's longitudinal direction. The energy storage device can be, for example, a battery or a fuel cell.

[0045] A third aspect concerns a working machine. The working machine has the drive train according to the first aspect. The drive train can be operated using the method described in the first aspect. The respective advantages and further characteristics can be found in the descriptions of the first and second aspects, respectively, whereby embodiments of the first aspect also constitute embodiments of the second and third aspects, and vice versa. The driving force of the working machine can be provided electrically via the drive train. Brief description of the characters Fig. Figure 1 schematically illustrates in a side view a first embodiment of a working machine with an electrified drive train. Fig. Figure 2 schematically illustrates in a top view a second embodiment of a working machine with an electrified drive train. Fig. Figure 3 schematically illustrates a differential gear. Fig. Figure 4 schematically illustrates a first embodiment of a drive train. Fig. Figure 5 schematically illustrates a second embodiment of a drive train. Fig. Figure 6 schematically illustrates an arrangement of components of a powertrain in a top view. Fig. Figure 7 schematically illustrates an arrangement of components of a powertrain in a side view. Fig. Figure 8 schematically illustrates a front axle of a drive train. Fig. Figure 9 schematically illustrates a modular structure of a powertrain. Fig. Figure 10 schematically illustrates a modular structure of a powertrain. Fig. Figure 11 schematically illustrates a third embodiment of a drive train. Fig. Figure 12 schematically illustrates a fourth embodiment of a drive train. Fig. Figure 13 schematically illustrates a fifth embodiment of a drive train. Fig. Figure 14 schematically illustrates a sixth embodiment of a drive train. Fig. Figure 15 schematically illustrates a method for operating the drive train of the working machine. Detailed description of embodiments

[0046] Fig. Figure 1 illustrates a first embodiment of a working machine designed as a tractor in a schematic side view. This working machine has two axles, each with wheels 10 attached to one end, which form output elements of a drive train. In the embodiment of Fig. Figure 1 shows a first, rear-mounted axle arrangement 12. A second axle arrangement 14 is shown at the front. Since a drive motor is arranged coaxially with the associated wheels 10 in the first axle arrangement 12 and optionally in the second axle arrangement 14, there is ample installation space 16 between the two axle arrangements 12, 14 in the longitudinal direction of the vehicle and above the second axle arrangement 14 for an energy storage device for the drive train.

[0047] In Fig. Figure 2 shows a second embodiment of the tractor-type work machine in a top view. This differs from the first embodiment by the additional all-wheel drive connection 18 between the first axle arrangement 12 and the second axle arrangement 14. This enables all-wheel drive. The first axle arrangement 12 can also drive the second axle arrangement 14, allowing a single drive motor to provide all-wheel drive. Furthermore, this enables central braking of all wheels 10.

[0048] In Fig. Figure 3 schematically illustrates a differential gear 20, which is used in the two axle arrangements 12 and 14 and enables a space-saving coaxial arrangement. The differential gear has an input shaft 22, a first output shaft 24, and a second output shaft 26, which are arranged coaxially to each other. The two output shafts 24 and 26 are operatively connected to opposing gears 10 on the driven machine. The input shaft 22 is driven by a drive motor, which, in the embodiments shown here, is permanently and rotationally fixed to the input shaft 22. The differential gear has a first planetary gear set 30 with a first sun gear 32, a first planet carrier 34, and a first ring gear 36, as well as a second planetary gear set 40 with a second sun gear 42, a second planet carrier 44, and a second ring gear 46.The first planet carrier 34 has two planet gears 38 rotatably mounted on it, which mesh with the first sun gear 32 and the first ring gear 36. The second planet carrier 44 has two planet gears 48 rotatably mounted on it, which mesh with the second sun gear 42 and the second ring gear 46. The first ring gear 36 is permanently and rotationally fixed to the second sun gear 42, with these being formed integrally by a hollow gear having internal and external teeth. The two planet gear sets 30, 40 are radially stacked, with the second planet gear set 40 arranged radially outside the first planet gear set 30. The second planet carrier 44 is fixed to a stationary component. The first planet carrier 34 forms the first output shaft 24 or is permanently and rotationally fixed to it. The second ring gear 46 forms the second output shaft 26 or is permanently and rotationally fixed to it.The first sun gear 32 forms the input shaft 22 or is permanently and rotationally fixed to it.

[0049] The differential gear 20 has a differential lock 50, which is designed as a friction-fit switching element. By means of the differential lock 50, the first planet carrier 34 and the second ring gear 46, and thus also the two output shafts 24, 26, can be connected to each other in a rotationally fixed manner.

[0050] Fig. Figure 4 schematically illustrates a first embodiment of a drive train for the previously discussed embodiments of a working machine. The drive train comprises the first axle arrangement 12. The first axle arrangement 12 comprises a first electric machine 60 with a first motor shaft 62, a first differential gear 20, which, like the one in Figure 4, Fig. The differential gear 20 shown in Figure 3 comprises a first output shaft 64, a second output shaft 66, a first output element 68, and a second output element 70. The first output element 68 forms the right rear wheel 10, and the second output element 70 forms the left rear wheel 10. The first motor shaft 62 is mechanically connected to the first output shaft 64 and the second output shaft 66 via the differential gear 20, with the first motor shaft 62 being permanently and rotationally fixed to the first sun gear 32. The first sun gear 32 is permanently and rotationally fixed to the first output shaft 64, and the second ring gear 46 is permanently and rotationally fixed to the second output shaft 66. The first motor shaft 62, the first output shaft 64, and the second output shaft 66 are arranged coaxially with each other.

[0051] The first output shaft 64 is mechanically connected to the first output element 68, in the illustrated embodiment via a further planetary gear 72 without a pivot. The second output shaft 66 is mechanically connected to the second output element 70, in the illustrated embodiment via a further planetary gear 72 without a pivot. The first output element 68 can be braked via a first service brake 74, which is connected to the associated planetary gear 72 and is designed as a disc brake. The second output element 70 can be braked via a second service brake 76, which is connected to the associated planetary gear 72 and is designed as a disc brake.

[0052] The powertrain of Fig. The 4 optionally features an all-wheel drive switching element 80 and also optionally an all-wheel drive effective connection 18. This allows the first motor shaft 62 to be mechanically switched and effectively connected to the second axle arrangement 14. The all-wheel drive switching element 80 is designed as a multi-plate clutch. The all-wheel drive effective connection 18 has a spur gear stage 84 and a bevel gear stage 82. A first bevel gear 86 of the bevel gear stage 82 is permanently and rotationally fixed to the first motor shaft 62. A second bevel gear 88 of the bevel gear stage 82 is permanently and rotationally fixed to a spur gear of the spur gear stage 84. The spur gear stage 84 has a gear 90 which meshes with a spur gear at one axial end and with another spur gear at the opposite axial end. This allows the all-wheel drive connection 18 to be easily guided along the first motor shaft 62 in the longitudinal direction of the vehicle to the second axle arrangement 14.The all-wheel drive connection 18 is arranged axially to the first axle assembly 12, and thus transversely to the vehicle, between the first electric motor 60 and the differential gear 20. The axial direction of the first axle assembly 12 corresponds to the axial direction of the first output shaft 64.

[0053] In Fig. Figure 4 does not show the second axle arrangement 14. One possible design of this second axle arrangement 14 is shown in Fig. 8 shown, which will be described later.

[0054] The drive train includes a first power take-off (PTO) drive. The PTO drive comprises a first PTO electric motor 92 with a first PTO motor shaft 94 and a first PTO shaft 96. The first PTO electric motor 92 is arranged longitudinally in front of the first axle assembly 12, and the first PTO shaft 96 is located behind the first axle assembly 12. This allows for efficient use of the available installation space. The first PTO shaft 96 protrudes from the rear of the machine for the connection of an implement. The first PTO motor shaft 94 is mechanically connected to the first PTO shaft 96 by a PTO coupling 98. The PTO coupling 98 has several spur gear stages, a planetary gear set 104, a PTO switching element 100, and connecting shafts. The PTO switching element 100 allows the first PTO electric motor 92 to be disconnected from the first PTO shaft 96.The first PTO electric motor 92 drives a main hydraulic pump 102 via spur gear stages, whereby the main hydraulic pump 102 can continue to operate even when the first PTO shaft 96 is to be stationary, thanks to the PTO switching element 100. The first PTO connection 98 extends from the first PTO motor shaft 94 to the first PTO shaft 96 orthogonally to the first axle assembly 12 and thus to the axial direction of the first output shaft 64 between the first electric motor 60 and the differential gear 20. This allows the first PTO connection 98 to pass through the axle assembly 12 in a space-saving manner.

[0055] The drive arrangement includes three additional electric motors 110, each of which drives an associated pump 112. This allows the control hydraulics, lubrication, and respective switching elements to be supplied with pressure independently of the drive power and work output.

[0056] The drive train includes a detection device 502. The detection device 502 is designed to detect an impending overspeed at the first electric motor 60 and, in some embodiments, at a second electric motor 60. In some embodiments, the detection device 502 is alternatively or additionally designed to detect an impending overspeed at the respective dispensing electric motors, such as the first dispensing electric motor 92. For this purpose, the detection device 502 detects the speed of the driven machine and its acceleration. In one embodiment, a planned route and, alternatively or additionally, a load condition are also taken into account, which can be entered into or transmitted to the detection device 502 for detection.In the case of the PTO electric machines 92, the impending overspeed can also be detected based on these parameters if a software-controlled ground-speed PTO function or a mechanical coupling for the ground-speed PTO function (which is not present in this embodiment) is activated. Alternatively, the speed and acceleration of the first PTO shaft 96 are recorded by a sensor.

[0057] Furthermore, the drive train includes a control device 500. The control device 500 is designed to activate a protective measure for the respective electric motors 60, which are configured as traction motors, and, if provided, the dispensing electric motor 92, in response to their respective impending overspeed. In the case of the electric motors 60 configured as traction motors, the electric motors 60 are initially operated in a generator mode. This charges an energy storage device of the drive train. It also results in a deceleration. During operation of the electric motors 60 in generator mode, the charge level of an energy storage device of the drive train is monitored by the control device 500, which is configured for this purpose as a monitoring device.From a certain charge level, at least some of the electrical power generated by the generator mode is dissipated as heat instead of being used to charge the energy storage device. If this is insufficient to prevent overspeed, the control device 500 can additionally actuate the service brake of the drive train, such as the service brake 74, 76, or 300. Alternatively or additionally, in the case of the first power take-off generator 92, the power take-off switching element 100 can be opened to disconnect the power take-off shaft 96.

[0058] Activating the protective measure can reduce driving stability when the machine is towing a trailer. The control device 500 can be configured to intervene to increase driving stability when the protective measure is activated. For example, individual wheels can be braked, and alternatively or additionally, a steering intervention can be performed.

[0059] The drivetrain and other embodiments can be combined accordingly with the one described in Fig. The procedures illustrated in Figure 15 are operated as follows. In step 600, an impending overspeed is detected in the first electric motor 60, the optionally provided second electric motor 60, and in the dispensing electric motors, such as the first dispensing electric motor 92. In step 602, in response to the detected impending overspeed, the protective measure is activated for the electric motor 60 or 92 in which the impending overspeed was detected.

[0060] In other embodiments, the overspeed is only detected in the first dispensing electric motor 92, the first electric motor 60 or the second electric motor 60 and then the protective measure is only activated for this electric motor 60, 92.

[0061] Fig. Figure 5 schematically illustrates a second embodiment of the drive train, which differs from the first embodiment only in the design of the all-wheel drive connection 18. Therefore, only these differences will be explained.

[0062] Specifically, the all-wheel drive connection 18 also features a spur gear stage 84 and a bevel gear stage 82, but these are connected differently. Instead of the bevel gear stage 82, the spur gear stage 84 is now directly connected to the first motor shaft 62. A first spur gear 120 of the spur gear stage 84 is permanently and rotationally fixed to the first motor shaft 62. A second spur gear 122 of the spur gear stage 84 is permanently and rotationally fixed to a bevel gear 124 of the bevel gear stage 82. This results in a lower rotational speed at the bevel gear stage 82 during operation.

[0063] The Fig. Figure 6 illustrates a possible spatial arrangement of the components of the drive assembly in a top view. Fig. Figure 7 illustrates the possible spatial arrangement of the components of the drive assembly in a side view. This spatial arrangement can be applied to all embodiments of the drive train and the driven machine. Arrow 154 illustrates in Fig. 6 and Fig. 7 each in a forward direction with the work machine. In Fig. 6 is part of a connection to the power take-off shaft 96, represented symbolically only by an arrow. Fig. 7 is part of the connection between the power take-off shaft 96 and the power take-off generator 92, represented symbolically only by an arrow. The power take-off generator 92 is in Fig. 7 is not shown. Likewise, in Fig. 7. The main hydraulic pump 102 is not shown. In Fig. 6 and Fig. Figure 7 does not illustrate the control device 500 or the detection device 502.

[0064] As can be seen, the all-wheel drive connection 18 and the PTO connection 98 are arranged in an axial direction of the first axle assembly 12 between the differential gear 20 and the first electric motor 60. The differential lock 50 is arranged on the side of the differential gear 20 facing away from the first electric motor 60, although a reverse arrangement is also possible. A connection 150 between the first output shaft 64 and the first output element 68, as well as a connection 150 between the second output shaft 66 and the second output element 70, can be modified modularly, as will be explained below. For example, the connection can be designed as a pivoted link instead of the rigid link shown so far.

[0065] In Fig. Figure 7 shows that both the all-wheel drive connection 18 and the PTO connection 98 pass an axis 160 of the first axle arrangement 12, which passes below a rotation axis of the first output shaft 64, the second output shaft 66, and the first engine shaft 62 in the vehicle's vertical direction. For the sake of simplicity, the following are shown in Fig. 7 not all shafts of the first axle arrangement 12 are shown.

[0066] Fig. Figure 8 schematically illustrates an embodiment of the second axle arrangement 14. As can be seen, the second axle arrangement 14 is almost identical to the first axle arrangement 12 according to Figure 8. Fig. 4. Identical components are therefore provided with the same reference numeral, even if they are designated differently for identification purposes. In this embodiment, no power take-off (PTO) drive is provided at the front, although a second PTO drive for a front PTO shaft can also be provided. The second axle assembly 14 also has a differential gear 20, which is referred to here as the second differential gear 20. In addition, the second axle assembly 14 has a second electric motor 60 with a second motor shaft 62. The two output elements 68, 70 are each mechanically connected to the second differential gear 20 via a planetary gear 72. The all-wheel drive connection 18 of the second axle assembly 14 also extends orthogonally between the second electric motor 60 and the differential gear 20 in the transverse direction of the vehicle.

[0067] The two output shafts 24, 26 of the differential 20 are permanently and rotationally fixedly connected to the two output shafts 64, 66 in the second axle arrangement 14. However, the two output shafts 64, 66 are not rigidly connected to the two output elements 68, 70, but rather articulated. For this purpose, a joint 160 is arranged in the rotationally fixed connection between the two output shafts 64, 66 and an input shaft 22 of the associated planetary gear 72. This joint 160 allows the output elements 68, 70, or the left front wheel and the right front wheel 10, to pivot about an axis of the joint 160 extending in the vertical direction of the vehicle. This enables steering at the front axle. No all-wheel drive switching element 80 is provided adjacent to the second axle arrangement 14, since one all-wheel drive switching element 80 is sufficient to connect the two axle arrangements 12, 14.

[0068] Fig. 9 and Fig. Figure 10 illustrates a modular structure. Fig. Figure 9 illustrates three variants of the first axle arrangement 12 and the second axle arrangement 14. In Fig. In a first variant 200, the two output shafts 64, 66 and, alternatively or additionally, the connection 150 to the output elements 68, 70 are axially shorter. This allows for a drive train with a narrow track gauge, while a central part 210 remains identical. In the middle of the Fig. Figure 9 shows a second variant 202, in which the two output shafts 64, 66 and, alternatively or additionally, the connection 150 to the output elements 68, 70 have a normal axial length. This allows a drive train with a normal track width to be provided, while a central part 210 remains identical. The track width in the first variant 200 is therefore narrower than in the second variant 202. The axial extent of the central part 210 remains the same. Below is in Fig. Figure 9 shows a third variant 204, which has the same track width as the second variant 202. However, the connection 150 to the output elements 68, 70 of the two output shafts 64, 66 each has a joint 160, as shown in the second axle arrangement 14 in Fig. 8. This allows for modular selection of which axles of the machine are steered. For example, rear axle steering can be provided as an alternative or in addition to front axle steering. To provide sufficient installation space for the joints 160, shorter output shafts 64, 66 from the first variant 200 can be used. This further reduces the number of component variants.

[0069] In Fig. Figure 10 illustrates how the modular design can be used in a work machine. A first axle arrangement 12 with a power take-off (PTO) drive and thus a power take-off shaft 96 is shown. This first axle arrangement 12 can optionally have the joints 160 for rear-wheel steering, which are therefore shown with dashed lines. The second axle arrangement 14 can be coupled to the first axle arrangement 12 via the optional all-wheel drive connection 18 and also has the joints 160.

[0070] In Fig. 11 is a narrow-gauge variant, or the first variant 200 of the first axle arrangement 12, shown schematically in detail as the third embodiment of the drive train. The third embodiment of the drive train differs from the first embodiment only in the design of the brake system and the length of the two output shafts 64, 66. Therefore, only these differences are explained, and otherwise the same reference numerals are used. Fig. Furthermore, the optional electric motors 110 and pumps 112 were not shown.

[0071] In the third embodiment, the two service brakes 74, 76 are omitted. Instead, the drivetrain has a central service brake 300, which is designed to brake the all-wheel drive connection 18 between the first axle arrangement 12 and the second axle arrangement 14. The all-wheel drive connection 18 is permanently connected to at least one of the two axle arrangements 12, 14, with the central service brake 300 acting on a corresponding shaft. Furthermore, when the central service brake 300 is activated, the all-wheel drive switching element 80 is automatically closed. As a result, the central service brake 300 acts on both the rear axle and the front axle and on all output elements 68, 70. The central service brake 300 requires less axial installation space for the two axle arrangements 12, 14, which allows the central part 210 to have the design of the wide track despite the narrower track width.

[0072] In Fig. Figure 12 schematically depicts a fourth embodiment of the drive train. This fourth embodiment differs from the first embodiment only in that the all-wheel drive connection 18 is omitted. Furthermore, both the first axle arrangement 12 and the second axle arrangement 14 are shown, along with their arrangement on a frame 400 of the machine (shown with dashed lines). In one embodiment, this frame 400 also forms a housing for the central part 210.

[0073] In Fig. Figure 13 schematically depicts a fifth embodiment of the drive train. This fifth embodiment differs from the first embodiment in the design of the first power take-off (PTO) connection 98. The PTO switching element 100 is now located on the side of the PTO electric motor 92, relative to the first axle assembly 12, rather than on the side of the PTO shaft 96. Furthermore, the number of spur gears connecting the PTO motor shaft 94 and the main hydraulic pump 102 has been reduced. A central gear of the connecting spur gear stage is permanently and rotationally fixed to an axle extending under the first axle assembly 12 in the longitudinal direction of the vehicle. This axle is no longer connected to the PTO shaft 96 via the planetary gear set 104, but rather via a simple spur gear stage.The axial position of the PTO switching element 100 at the rear of the vehicle's longitudinal axis allows for the placement of an oil tank in a front area. Component complexity can be reduced, as a hollow shaft design for the all-wheel drive connection 18 is no longer necessary. Furthermore, increased efficiency is possible due to the reduced number of gear engagements. Additionally, a lower gear ratio may allow for overspeeding of the PTO shaft 96.

[0074] Furthermore, in the fifth embodiment, the design of the planetary gear sets 72, each of which mechanically connects the two output elements 68, 70 to the second differential gear set 20, differs. Instead of a planetary gear set with planet gears with simple teeth, stepped planetary gear sets are now provided. The stepped planetary gear sets have a first tooth that meshes only with the sun gear. The stepped planetary gear sets have a second tooth that meshes only with the ring gear and which has a smaller effective diameter than the first tooth. With the same radial diameter, this design of the planetary gear set 72 can have a higher gear ratio. In addition, in the fifth embodiment, the all-wheel drive connection is the same as in the second embodiment. Fig. 5 trained.

[0075] In Fig.Figure 14 schematically illustrates a sixth embodiment of the drive train. The sixth embodiment differs from the fifth embodiment in the design of the operative connection between the PTO motor shaft 94 and the main hydraulic pump 102. In the sixth embodiment, this operative connection is not provided by three spur gears, with a central spur gear meshing with both a motor-side and a pump-side spur gear, as in the fifth embodiment. Instead, this operative connection is provided by four spur gears, with two spur gears meshing with each other and two of these spur gears, located centrally in the power flow, being permanently and rotationally fixed to each other. In the fifth embodiment, the number of spur gears is small, resulting in high efficiency in driving the main hydraulic pump 102.In the sixth embodiment, the radial installation space required for the functional connection to the main hydraulic pump 102 is small, and an axial offset can be easily provided. Furthermore, a high gear ratio for driving the main hydraulic pump 102 can be provided in this way, even with a small installation space requirement. Reference sign 10 front and rear wheels 12 first axle arrangement 14 second axle arrangement 16 construction space 18 All-wheel drive connection 20 Differential gears 22 Input wave 24 first output wave 26 second output wave 30, 40, 104 planetary gear set 32 first sun wheel 34 first planetary carrier 36 first ring gear 38 first planetary gears 42 second sun wheel 44 second planetary carrier 46 second ring gear 48 second planetary gears 50 Differential lock 60, 110 electric machine(s) 62 Motor shaft 64 first output shaft 66 second output shaft 68 first output element 70 second output element 72 planetary gears 74, 76, 300 Service brake 80 All-wheel drive switching element 82 bevel gear stage 84 Spur gear stage 86, 88, 124 bevel gear 90 gear 92 Tapping electric machine 94 PTO shaft 96 PTO 98 Tap connection 100 dispensing switch elements 102 Main hydraulic pump 112 pump(s) 120 first spur gear 122 second spur gear 150, 152 connection 154 Arrow 160 axles / joints 200, 202, 204 variant 210 Central part 400 frames 500 control device 502 Detection device 600 steps of detecting impending overspeed Step 602 of activating the protective measure

Claims

[1] Method for operating a drive train of a working machine, wherein the drive train comprises at least a first electric machine (60) with a first motor shaft (62) for driving a first axle arrangement (12) and wherein the method comprises at least the following steps: - Detection (600) of an impending overspeed in the first electric motor (60); and - Activating (602) a protective measure for the first electric machine (60) in response to the impending overspeed. [2] Method according to claim 1, characterized by , that the protective measure involves operating the first electric machine (60) in a generator operating mode. [3] Method according to claim 2, characterized by, that when the first electric machine (60) is operated in generator mode, the charge level of an energy storage device of the drive train is monitored and, from a certain charge level, the electrical power generated by the generator mode is at least partially dissipated as heat. [4] Method according to any one of the preceding claims, characterized by , that the protective measure includes the application of a service brake (74, 76, 300) of the drive train. [5] Method according to any one of the preceding claims, characterized by , that the protective measure comprises an opening of an operative connection of the first electric machine (60) with an output element of the first axis arrangement (12). [6] Method according to any one of the preceding claims, characterized by , that the detection of the impending overspeed is dependent on at least one of the following parameters: - A speed; - An acceleration; - A derivative of acceleration; - A planned route; and - A loading condition. [7] Method according to any one of the preceding claims, characterized by , that the impending overspeed is detected when a speed threshold is exceeded. [8] Method according to any one of the preceding claims, characterized by , that the impending overspeed is detected by a prediction. [9] Method according to any one of the preceding claims, characterized by that the impending overspeed is detected using a machine learning model. [10] Drive train of a working machine, wherein the drive train comprises at least a first electric machine (60) with a first motor shaft (62) for driving a first axle arrangement (12), a detection device (502) which is designed to detect (600) an impending overspeed in the first electric machine (60), and a control device (500) which is designed to activate (602) a protective measure for the first electric machine (60) in response to its impending overspeed. [11] Drive train according to claim 10, wherein the drive train comprises a first axle assembly (12) and a first power take-off (PTO) drive, wherein the first axle assembly (12) comprises the first electric motor (60) with the first motor shaft (62), a first differential gear (20), a first output shaft (64), a second output shaft (66), a first output element (68) and a second output element (70), wherein the first PTO drive comprises a first PTO electric motor (92) with a first PTO motor shaft (94) and a first PTO shaft (96), wherein the first motor shaft (62) is mechanically connected to the first output shaft (64) and the second output shaft (66) via the differential gear (20), wherein the first motor shaft (62) is arranged coaxially with the first output shaft (64), and wherein the first output shaft (64) is mechanically connected to the first output element (68). is interconnected,wherein the second output shaft (66) is mechanically operatively connected to the second output element (70), wherein the first differential gear (20) comprises a first differential lock (50), a first planetary gear set (30) with a first sun gear (32), a first planet carrier (34) and a first ring gear (36) and a second planetary gear set (40) with a second sun gear (42), a second planet carrier (44) and a second ring gear (46), wherein the first ring gear (36) is permanently rotationally fixed to the second sun gear (42) and the two planetary gear sets (30, 40) are radially stacked, wherein the first power take-off motor shaft (94) is mechanically operatively connected to the first power take-off shaft (96), wherein a first power take-off operative connection (98) from the first power take-off motor shaft (94) to the first power take-off shaft (96) extends transversely to the first output shaft (64) between the first electric machine (60) and the differential gear (20) extends in an axial direction of the first output shaft (64). [12] Powertrain according to claim 11, characterized by , that the drive train has an all-wheel drive switching element (80) and a second axle arrangement (14), wherein the first motor shaft (62) is mechanically connected to the second axle arrangement (14) by means of the all-wheel drive switching element (80), wherein an all-wheel drive connection (18) from the first motor shaft (62) to the second axle arrangement (14) is connected between the first electric motor (60) and the differential gear (20) in an axial direction of the first output shaft (64) to the first output shaft (64). [13] Powertrain according to claim 12, characterized by , that the second axle arrangement (14) has at least one of the following components: - A second electric machine (60) with a second motor shaft (62), which is constructed and connected in the same way as the first electric machine (60); - A second differential gear (20); - A third output shaft; and - A fourth output shaft. [14] Powertrain according to claim 12 or 13, characterized by , that the first sun gear (32) is permanently connected to the first motor shaft (62) in a rotationally fixed manner, the first planet carrier (34) is permanently connected to the first output shaft (64) in a rotationally fixed manner, the second planet carrier (44) is fixed to a stationary component, and the second ring gear (46) is permanently connected to the second output shaft (66) in a rotationally fixed manner. [15] Working machine with a drive train according to any one of claims 10 to 14, characterized by , that a driving force of the working machine can be provided electrically by means of the drive train.

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