Method for controlling a driving behaviour of a work machine
Patent Information
- Application Number
- EP2023806178
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-11-11
- Filing Date
- 2023-11-08
- Publication Date
- 2025-09-17
AI Technical Summary
Existing work machines, such as wheel loaders, face challenges in maintaining consistent driving behavior during braking, as the available braking torque from recuperation may not meet the desired torque, leading to inconsistent braking experiences and potential mechanical wear when relying solely on mechanical brakes.
A method that acquires driver commands and battery charging information to determine desired and maximum braking torques, using recuperation and mechanical brakes in a coordinated manner to ensure consistent braking, with the mechanical brake taking over when desired torque exceeds the maximum recuperation torque, and controlling the electric machine for recuperation to support braking when possible.
This method ensures homogeneous driving behavior by seamlessly switching between recuperation and mechanical braking, reducing mechanical wear and allowing for efficient energy use, regardless of the braking torque provided, and can operate effectively with batteries of varying states and capacities.
Smart Images
Figure 1.1
Abstract
Description
[0001] Method for controlling the driving behavior of a work machine
[0002] Technical area
[0003] The present invention relates to a method for controlling the driving behavior of a work machine. Furthermore, the present invention relates to a control device configured to carry out the method for controlling the driving behavior of the work machine. Furthermore, the present invention relates to a drive assembly having such a control device, as well as to a work machine having such a drive assembly.
[0004] State of the art
[0005] Vehicles with a recuperation function are known from the state of the art. This function automatically decelerates the vehicle using recuperation when the accelerator pedal is released. If the vehicle's brake pedal is applied slightly, braking is initially performed using recuperation. If the brake pedal is applied more forcefully, braking is performed using a mechanical vehicle brake.
[0006] Description of the invention
[0007] In a first aspect, the present invention relates to a method for controlling the driving behavior of a work machine. The work machine can be an agricultural machine, a construction machine, or a transport machine. For example, the construction machine is a wheel loader. The wheel loader can be an electrically driven wheel loader in which both the propulsion and a working device, for example a lifting frame, can be driven electrically. The lifting frame can be driven by means of a lifting hydraulic system, which can have a pump driven by an electric motor. The driving behavior of the work machine can be longitudinal and, alternatively or additionally, lateral acceleration of the work machine. The work machine has a battery, an electric machine for propelling the work machine, and a mechanical brake.The battery can be designed to power a working device of the machine in addition to propulsion. The battery can be a lithium-ion battery for storing electrical energy in the form of chemical energy.
[0008] The electric machine can have an electric motor, for example a synchronous motor or an asynchronous motor. The electric machine can be operated as a generator and as a motor. The electric machine can be configured to drive the work machine using energy from the battery, for example via a transmission. For example, a stepped transmission and alternatively or additionally a continuously variable transmission can be provided. The work machine can have exactly one electric machine or alternatively more than one electric machine for driving the work machine. For example, several electric machines can be provided for driving the work machine, wherein one electric machine can be provided for driving the work machine per driven wheel or alternatively per driven axle. The electric machine can have an inverter.The inverter can be configured to convert the battery's DC voltage into AC voltage for the electric machine. Alternatively or additionally, the inverter can be configured to convert the AC voltage provided by the electric machine into DC voltage for the battery. The electric machine is configured to charge the battery with a charging current by means of recuperation, for example, via the inverter. Kinetic energy can be converted into electrical energy by means of recuperation. This electrical energy can be stored in the battery in the form of stored chemical energy.
[0009] The mechanical brake can have a multi-disk brake, for example a wet multi-disk brake. The mechanical brake can be continuously adjustable. The mechanical brake can be configured to brake the forward movement of the work machine. The work machine can have exactly one or, alternatively, more than one mechanical brake for braking the forward movement of the work machine. Furthermore, the work machine can have a control device for executing the method described below for controlling the driving behavior of the work machine. The control device can be electronically connected to further control devices of the work machine as well as to the battery and the electric motor for propelling the work machine.
[0010] The method comprises a step of acquiring information relating to a travel command from a driver of the work machine. Acquiring the information may comprise receiving the information relating to the travel command. The information relating to the travel command from the driver of the work machine may be acquired using sensors of the work machine. The travel command may relate to a desired longitudinal acceleration and, alternatively or additionally, a lateral acceleration of the work machine. The travel command may comprise an active deceleration and, alternatively or additionally, an acceleration of the work machine. A desired deceleration may be counter to the current direction of travel of the work machine, for example, to a standstill, or even to reversal, i.e., to reversing the current direction of travel of the work machine. The driver's travel command may be acquired directly, for example, via a sensor coupled to a control element.Alternatively or additionally, the driver's driving command can also be recorded indirectly, for example by recording a parameter that has a clearly defined relationship to the driver's driving command.
[0011] The method further comprises a step of detecting information about a maximum charging current of the battery. Detecting the information about the maximum charging current of the battery can comprise receiving this information. The information about the maximum charging current of the battery can be detected using sensors of the work machine. Detecting can comprise actively querying the information about the maximum charging current of the battery. Detecting the information about the maximum charging current of the battery can comprise actively transmitting the information about the maximum charging current of the battery. Detecting can be time-controlled and, alternatively or additionally, event-controlled. Information about the maximum charging current of the battery can comprise an absolute value and, alternatively or additionally, a relative value of the maximum charging current of the battery. Information about the maximum charging current of the battery can comprise a maximum charging power of the battery.In this step, the maximum charging current can be measured directly or indirectly via a parameter that has a clearly defined relationship to the maximum charging current. The maximum charging current can depend on the battery type, the state of charge (i.e., the current capacity of the battery), environmental parameters such as the ambient temperature, and other parameters.
[0012] The method further comprises a step of determining information about a desired braking torque as a function of the acquired information about the driver's driving command. Determining information about a desired braking torque can comprise determining a desired braking torque in Newton meters. Determining information about the desired braking torque can comprise determining a desired negative acceleration of the work machine. The desired braking torque can then be determined based on the desired acceleration and further vehicle data, for example the mass of the vehicle. The method further comprises a step of determining information about a maximum braking torque of the electric machine as a function of the acquired information about the maximum charging current of the battery.Determining the information on the maximum braking torque can comprise determining a maximum braking torque in Newton meters. Determining the information on the maximum braking torque can comprise determining a maximum negative acceleration of the work machine. Determining the information on the maximum braking torque can comprise determining a matching charging current. The maximum braking torque can be determined such that this braking torque can be generated to the maximum by the electric machine by means of recuperation with the maximum charging current. The method further comprises a step of comparing the information on the desired braking torque with the information on the maximum braking torque. For example, the desired braking torque can be compared with the maximum braking torque. The absolute values of the desired and maximum braking torque can be compared with one another.
[0013] The method further comprises a step of sending a signal for controlling the mechanical brake if the desired braking torque is greater than the maximum braking torque. Alternatively, the method comprises a step of directly controlling the mechanical brake if the desired braking torque is greater than the maximum braking torque. The sending of the control signal can occur after the signal has been determined. The control of the mechanical brake can occur such that braking occurs with at least a fraction of the desired braking torque or, in particular, with the entire desired braking torque by the mechanical brake.
[0014] Using this method, the driving behavior of the work machine can be represented independently of the braking torque that can be provided by recuperation. If the desired braking torque cannot be provided by recuperation, braking is performed using the mechanical brake. This makes it possible to provide a homogeneous driving behavior in which the desired braking torque can be generated at least by means of the mechanical brake.
[0015] According to a further embodiment, the method can be characterized in that the method comprises controlling the electric machine for braking with a recuperation braking torque if the desired braking torque is greater than the maximum braking torque. In this case, the electric machine, in particular the inverter of the electric machine, can be controlled such that the recuperation braking torque can be controlled by means of a controllable resistor of the electric machine, in particular the inverter. Controlling the electric machine for braking with the recuperation braking torque can be controlling the electric machine for recuperation. According to this further embodiment, sending the signal for controlling the mechanical brake can further comprise sending a differential braking torque. The differential braking torque at the mechanical brake can be controllable via an adjustable pressure of the mechanical brake.The differential braking torque can be a difference between the desired braking torque and the regenerative braking torque. The regenerative braking torque can be less than or equal to the maximum braking torque. The control of the electric motor for recuperation and the transmission of the signal to control the mechanical brake can take place in parallel. The method can further comprise a step of controlling the electric motor for recuperation if the desired braking torque is less than or equal to the maximum braking torque. In addition, to control the electric motor for recuperation, if the desired braking torque is less than or equal to the maximum braking torque, the signal to control the mechanical brake can be sent. In this way, braking via recuperation can be additionally supported by braking via the mechanical brake.
[0016] A method for controlling the driving behavior of a work machine is shown, wherein consistent driving behavior of the work machine during braking is ensured, regardless of whether the signal is sent to activate the mechanical brake or the electric motor is activated for braking. If the desired braking torque is greater than the maximum braking torque, the work machine can be braked solely or primarily by actuating the mechanical brake. If the desired braking torque is less than or equal to the maximum braking torque, the work machine can be braked solely or primarily by actuating the electric motor for recuperation.When driving a work machine with such a method for controlling the driving behavior of the work machine, the driver cannot distinguish whether braking occurs due to the activation of the mechanical brake or due to the activation of the electric motor for braking, i.e. for recuperation. Consistent driving behavior can be achieved regardless of whether braking is carried out by the mechanical brake or by recuperation. Depending on whether enough charging current can be sent to the battery, the method decides whether and to what extent the mechanical brake and the electric motor are activated. The method for controlling the driving behavior of the work machine can be used to enable particularly resource-efficient driving behavior of the work machine.Even with desired braking torques that exceed the maximum braking torque, recuperation can occur to the extent permitted by the maximum braking torque, and thus the maximum battery charging current. At the same time, complete braking with the desired braking torque by the mechanical brake can be avoided. This also reduces mechanical wear on the mechanical brake.
[0017] According to a further embodiment, braking can be carried out with the
[0018] Differential braking torque can be achieved at a constant rate over time by sending the signal to activate the mechanical brake. For example, the differential braking torque can be approximately 80% of the desired braking torque. The mechanical brake can be controlled in such a way that it achieves this 80% of the desired braking torque at a constant rate over time. According to this further embodiment, braking with the recuperation braking torque can be achieved at a variable rate over time by controlling the electric motor. For example, the recuperation braking torque, through its relationship with the differential braking torque, can be approximately 20% of the desired braking torque. However, the temporal variability can be used to vary this approximately 20% upwards or downwards.
[0019] For example, during braking, the system can react to a change in the incline of the surface on which the machine is traveling. The signal to activate the mechanical brake can always be sent in such a way that the mechanical brake provides a constant differential braking torque. The electric motor for recuperation can then be controlled in such a way that it provides the recuperation braking torque at a variable time, allowing it to react dynamically to changing environmental parameters, such as the incline of the surface. This provides a method for controlling the driving behavior of the machine that is designed for various situations.
[0020] According to a further embodiment, the maximum charging current of the battery can depend on a state of the battery. The state of the battery can depend on external influences. The external influences can be, for example, temperature or pressure. The state of the battery can include the age of the battery. The state of the battery can include the state of charge of the battery. The state of the battery can include the maximum charging capacity of the battery. For example, in a newly produced battery stored at an optimal temperature, a relatively high maximum charging current can be present if the relative state of charge of the battery is low, for example, 10% of the maximum capacity of the battery. If the relative state of charge is high, for example, 80-90% of the maximum capacity of the battery, the maximum charging current can be lower.Alternatively, the charging current can be lower if the temperature is particularly low or high, or if the battery is particularly old. The method can therefore react to changing battery conditions, for example changing battery charge levels. The method can therefore also be used for work machines with batteries in sub-optimal conditions. The method can react dynamically to, for example, aged batteries, batteries in a sub-optimal temperature window or heavily charged batteries. The method can therefore be used for a wide range of work machines with batteries for propulsion and recuperation. This means that a work machine can be operated in a resource-saving manner even with old or relatively small batteries, i.e. with a low maximum capacity.Expensive oversizing of the battery is eliminated, as smaller batteries can also be used to generate similar driving behavior. Without the driving behavior control method, a battery with a larger capacity and thus a higher maximum charging current would otherwise be required to provide the same driving behavior across a wide range of charge states. With this method, an existing battery can be optimally utilized while simultaneously maintaining the same driving behavior.
[0021] According to a further embodiment, detecting information about the driving command can include detecting information about a pedal position and detecting information about a direction switch position. The pedal and the direction switch can be included in the work machine. In particular, the work machine can have only one pedal. Thus, one-pedal driving can be implemented together with the direction switch.
[0022] According to a further embodiment, the method can further comprise determining a desired direction of travel depending on the detected information regarding the position of the direction switch. The detected information regarding the position of the direction switch can comprise information regarding a desired direction of travel, i.e., the direction in which the driver wishes to travel. For example, the driver can operate the direction switch from forward to reverse, and the desired direction of travel can then be reverse. The desired direction of travel can comprise changing the position of the direction switch. The information regarding the position of the direction switch can be detected once at the beginning of the method for controlling the driving behavior. A specific position of the direction switch can be detected, and the method can be executed depending on this detected position of the direction switch.For example, a deceleration request from the driver can be detected such that a change in direction is detected by the direction switch. The information on the desired braking torque can be determined depending on the determined direction of travel request. Furthermore, the method according to the embodiment can comprise detecting information on a current direction of travel. The detection of the information on the current direction of travel can be dependent on detecting a current driving speed. According to the embodiment, the method can further comprise controlling the electric machine to accelerate the work machine in the direction of the desired direction of travel if the direction of the desired direction of travel and the current direction of travel are different.The electric motor can be controlled to accelerate the working machine after the signal to control the mechanical brake has been sent, and alternatively or additionally after the electric motor has been controlled for recuperation. The electric motor can be controlled to accelerate after braking by the electric motor and alternatively or additionally after braking by the mechanical brake.
[0023] This means that the process can also be used for reversing, i.e., changing the direction of travel from forward to reverse, and vice versa. The driver cannot distinguish whether the machine is decelerating through recuperation or through braking using the mechanical brake. The driving behavior is thus homogeneous, regardless of whether braking is applied mechanically or electrically.
[0024] According to a further embodiment, the method can further comprise determining a driving request depending on the detected information on the position of the pedal, which can include determining a driving speed. The detected information on the position of the pedal can comprise information on a driving request, i.e., how fast a driver wishes to travel in a particular direction. A driving request from the driver can be present, for example, when the driver stops pressing the pedal. Furthermore, the driving request can comprise pressing the pedal. The information on the position of the pedal can be detected once at the beginning of the method for controlling driving behavior. A specific position of the pedal can be detected, and the method can be executed depending on this detected position of the pedal.The information regarding the desired braking torque can be determined based on the specific driving requirement. The desired braking torque can be determined based on the specific driving speed. For example, a higher desired braking torque can be determined at higher driving speeds in the opposite direction to the current direction of travel. Alternatively or additionally, the desired braking torque can be determined based on the current driving speed of the work machine. For example, a higher desired braking torque can be determined at higher driving speeds.
[0025] Thus, a method is shown in which the driver actively specifies a direction of travel and a speed of travel, and in the process a desired braking torque can be indirectly determined. This allows the driver to influence the driving behavior of the work machine particularly easily using one-pedal driving. For example, while traveling forwards, the driver can change the position of the direction switch from forward to reverse and maintain the position of the pedal. The travel command therefore includes reversing the work machine from forward to reverse at the same absolute speed. Braking can occur automatically as a result of the process reversing the work machine. Active braking by the driver, for example via a brake pedal, is not necessary.The direction of travel can be determined by the direction switch, and the degree of pressing the pedal can be adjusted by the degree of absolute speed.
[0026] According to a further embodiment, the signal for controlling the mechanical brake can be sent to a vehicle control device for controlling the mechanical brake. The signal can be sent via a vehicle bus, such as CAN or Flexray. The vehicle control device can be separate from the control device that can execute the method.
[0027] A distinction can thus be made between the control devices, with one implementing the control of the mechanical brake and another implementing the control of the electric motor for recuperation. The responsibility for controlling the mechanical brake can thus be outsourced from the control unit that executes the method for controlling the driving behavior of the work machine. Thus, special safety requirements that may be provided for controlling the mechanical brake can be outsourced to another control unit, in this case the vehicle control device. Alternatively, the control device can directly execute the control of the mechanical brake to execute the method for controlling the driving behavior of the work machine.
[0028] In a second aspect, the present invention relates to a control device which is configured to carry out a method for controlling a driving behavior of a work machine according to one of the embodiments of the first aspect.
[0029] In a third aspect, the present invention relates to a drive assembly comprising an electric machine and a control device according to the second aspect of the invention. The electric machine may comprise an inverter.
[0030] In a fourth aspect, the present invention relates to a work machine with a battery, a mechanical brake, a vehicle control device for controlling the mechanical brake, and a drive group according to the third aspect of the invention. The work machine can be a construction or agricultural machine or a transport machine. The work machine can be an off-highway vehicle. The work machine according to this aspect of the invention can be configured to carry out the method according to an embodiment according to the first aspect of the invention, wherein the work machine can further be configured to carry out further mentioned steps, such as controlling the mechanical brake and braking by the electric machine and by the mechanical brake. Brief description of the figures
[0031] Figure 1 schematically shows a work machine according to an embodiment of the present invention.
[0032] Figure 2 shows schematically a drive group of the working machine according to the embodiment of Figure 1.
[0033] Figure 3 schematically shows steps of a method for controlling a driving behavior of the work machine from Figure 1.
[0034] Figure 4 shows characteristic curves of a battery of the working machine from Figure 1 .
[0035] Detailed description of embodiments
[0036] Figure 1 shows a schematic view of a work machine 2 according to an embodiment of the present invention. The work machine 2 has a drive group 18, a battery 4, a mechanical brake 8, a vehicle control device 16, a pedal 10, and a direction switch 12, as shown in Figure 2. The drive group 18 has a control device 14 and an electric machine 6. The pedal 10 and the direction switch 12 are electronically connected to the vehicle control device 16. The mechanical brake 8 is also electronically connected to the vehicle control device 16. The vehicle control device 16 is configured to control the mechanical brake 8 and to acquire information from the pedal 10 and the direction switch 12, via which the driver can input a driving command. The pedal 10 and the direction switch 12 send electronic signals to the vehicle control device 16.The vehicle control device 16 is electronically connected to the control device 14 of the drive group 18. The control device 14 is further electronically connected to the battery 4 and the electric machine 6. The electric machine 6 has an inverter, not shown in the figures, and is electrically connected to the battery 4. The electric machine 6 can be driven by means of the energy stored in the battery 4 and can recuperate energy into the battery 4. The control device 14 is configured to carry out the method described below with reference to Figures 3 and 4 for controlling the driving behavior of the work machine 2. In a first step S1, information relating to a driving command from a driver of the work machine 2 is acquired. In this step S1, information relating to a position of the pedal 10 is acquired in a step S1.1, and in a step S1.2 a detection of information about a position of the direction switch 12. The information about the position of the pedal 10 and the position of the direction switch 12 is detected by means of the vehicle control device 16 and transmitted to the control device 14, which reads it in.
[0037] In a further step S2, the method comprises recording information about the maximum charging current of the battery 4. The maximum charging current of the battery 4 depends on a state of charge of the battery 4. Figure 4 shows a charging or discharging power B of the battery 4 against a state of charge A of the battery 4. Curve C shows the charging power of the battery 4 as a function of the state of charge of the battery 4, and curve D shows the discharging power of the battery 4 as a function of the state of charge of the battery 4. Up to a value of the maximum state of charge of the battery for optimal charging power F, the charging power B of the battery 4 increases with increasing state of charge A. From this value F, the charging power B of the battery 4 decreases with increasing state of charge A above a value G, which characterizes the maximum state of charge of the battery 4 for charging by recuperation, to a value H, which characterizes the maximum state of charge of the battery 4 for charging.The value I denotes the maximum state of charge of the battery, approximately 100%. The states of charge G and H are each lower than the state of charge I. The curve of the discharge power D of battery 4 runs through small values of the state of charge of battery 4 close to zero and, starting at a value E, which denotes the minimum state of charge of battery 4 for discharge, increases with increasing state of charge, initially sharply and then more slowly, up to the maximum state of charge I.
[0038] In the step S2 of detecting information about the maximum charging current of the battery 4, the control device 14, in the present embodiment, queries the current charge level A of the battery 4. Depending on the current charge level, the maximum charging power B, and thus the maximum charging current of the battery 4, can be determined, for example, calculated, using the relationship shown in Figure 4. For this purpose, the relationships shown in Figure 4 are stored in a memory of the control device 14.
[0039] In a step S3.1, information relating to a desired braking torque is determined as a function of the information relating to the driver's driving command acquired in step S1. In the present embodiment, a desired braking torque is determined in Newton meters. Depending on the position of pedal 10 and the position of direction switch 12 acquired in step S1, a desired driving direction is determined in step S3.2 and a driving request is determined in step S3.3. The driving request can be a driving speed. The desired braking torque is determined in step S3.1 as a function of the desired driving direction determined in step S3.2 and the driving request determined in step S3.3. In a step S4, information relating to a maximum braking torque of electric machine 6 is determined.In the present embodiment, the maximum braking torque of the electric machine 6 is determined in Newton meters depending on the information from the context of Figure 4.
[0040] A comparison S5 then takes place between the braking torque determined in step S3.1 and the maximum braking torque determined in step S4. Consequently, the driver's desired braking torque is compared with the maximum braking torque provided by the electric machine 6.
[0041] If the desired braking torque is less than or equal to the maximum braking torque, the electric machine 6 is activated for recuperation in a step S7. For this purpose, for example, an inverter of the electric machine 6 can be activated accordingly. In this case, braking is carried out solely by the electric machine 6 by means of recuperation. If, however, the comparison step S5 shows that the desired braking torque is greater than the maximum braking torque, the method further comprises a step S6 of sending a signal to activate the mechanical brake 8. For example, the driver requests a greater braking torque than the electric machine 6 can provide by means of recuperation. The maximum braking torque can be small, for example, at high relative charge states A of the battery 4, as can be seen from Figure 4.In this case, the electric machine 6 is activated S7 for recuperation in order to further convert braking energy into electrical energy and protect the mechanical brake 8. In particular, the method of the present embodiment also utilizes the range of high relative states of charge A of the battery 4 between F and G, shown in Figure 4. In step S6, however, the control device 14 also activates the mechanical brake 8, which provides the difference between the desired braking torque and the maximum braking torque of the battery 4. The method thus makes it possible to use batteries with high relative states of charge and, at the same time, to maintain homogeneous driving behavior for the driver despite recuperation.
[0042] If, for example, the driver has requested a change of direction of travel via the direction switch 12, which is determined in step S3.2, after braking, which can be carried out by means of recuperation by the electric machine 6 and battery 4 as well as by the mechanical brake 8, the electric machine 6 is activated S9 to accelerate the work machine 2. The activation S9 takes place as a function of a step S8 in which it is determined whether the current and desired direction of travel are different.
[0043] Reference symbol
[0044] 2 working machines
[0045] 4 Battery
[0046] 6 electric machine
[0047] 8 mechanical brake
[0048] 10 Pedal
[0049] 12 direction switch
[0050] 14 Control device (of the drive group)
[0051] 16 Vehicle control device
[0052] 18 Drive group
[0053] 51 (Step) Recording information about a drive command
[0054] 51 .1 (Step) Acquiring information about a pedal position
[0055] 51 .2 (Step) Recording information on a position of the
[0056] Direction switch
[0057] 52 (Step) Collecting information on a maximum charging current
[0058] 53.1 (Step) Determining information about a desired braking torque
[0059] 53.2 (Step) Determining a desired direction of travel
[0060] 53.3 (Step) Determining a driving request
[0061] 54 (Step) Determining information on a maximum braking torque of the electric machine
[0062] 55 (Step) Compare the information on the desired braking torque with the information on the maximum braking torque
[0063] 56 (Step) Sending a signal to control the mechanical brake
[0064] 57 (Step) Control of the electric machine for recuperation
[0065] 58 (Step) Recording information about a current direction of travel
[0066] 59 (Step) Control of the electric machine to accelerate the
[0067] Work machine
[0068] A (Axis) Battery charge level
[0069] B (Axis) Charging or discharging power of the battery
[0070] C (curve) Battery charging power
[0071] D (curve) Battery discharge power
[0072] E (value) minimum battery charge level for discharge F (value) maximum battery charge level for optimal charging performance
[0073] G (value) maximum state of charge of the battery for charging by recuperation
[0074] H (value) maximum charge level of the battery for charging
[0075] I (value) maximum charge level of the battery
Claims
Patent claims 1. Method for controlling the driving behavior of a working machine (2), wherein the working machine (2) comprises a battery (4), an electric machine (6) for propelling the working machine (2) and a mechanical brake (8), wherein the electric machine (6) is configured to charge the battery (4) with a charging current by means of recuperation, and wherein the method comprises the steps: Acquiring (S1) information about a driving command from the driver of the working machine (2), acquiring (S2) information about a maximum charging current of the battery (4), determining (S3.1) information about a desired braking torque as a function of the acquired information about the driving command of the driver, determining (S4) information about a maximum braking torque of the electric machine (6) as a function of the acquired information about the maximum charging current of the battery (4), comparing (S5) the information about the desired braking torque with the information about the maximum braking torque, sending (S6) a signal to control the mechanical brake (8) if the desired braking torque is greater than the maximum braking torque.
2. Method according to claim 1, characterized in that the method comprises controlling (S7) the electric machine (6) to brake with a recuperative braking torque, and the sending (S6) of the signal to control the mechanical brake (8) comprises sending a differential braking torque if the desired braking torque is greater than the maximum braking torque, wherein the differential braking torque is a difference between the desired braking torque and the recuperative braking torque.
3. Method according to claim 2, characterized in that braking with the differential braking torque is carried out in a time constant manner by sending (S6) the signal to control the mechanical brake (8) and braking with the recuperation braking torque is carried out in a time variable manner by controlling (S7) the electric machine (6).
4. Method according to one of the preceding claims, characterized in that the acquisition (S1 ) of information relating to the driving command is an acquisition (S1.1 ) includes information on the position of a pedal (10) and the acquisition (S1.2) of information on the position of a direction switch (12).
5. Method according to claim 4, characterized in that the method comprises determining (S3.2) a desired direction of travel depending on the acquired information on the position of the direction switch and acquiring (S8) information on a current direction of travel, wherein controlling (S9) the electric machine (6) to accelerate the working machine (2) in the direction of the desired direction of travel takes place if the direction of the desired direction of travel and the current direction of travel are different.
6. Method according to claim 5, characterized in that determining (S3.3) a driving request as a function of the acquired information on the position of the pedal (10) includes determining a driving speed.
7. Method according to one of the preceding claims, characterized in that the sending (S6) of the signal for controlling the mechanical brake (8) to a vehicle control unit (16) for controlling the mechanical brake (8) is carried out.
8. Control device (14) which is configured to execute a method for controlling the driving behavior of a working machine (2) according to any one of claims 1 to 7.
9. Drive group (18) comprising an electric machine (6) and a control device (14) according to claim 8.
10. Working machine (2) comprising a battery (4), a mechanical brake (8), a vehicle control unit (16) for controlling the mechanical brake (8) and a drive group (18) according to claim 9.