Method for operating motor vehicle and corresponding motor vehicle

Abstract

The invention relates to a method for operating a motor vehicle (1) having at least one electric machine (3) by means of which a regenerative torque intended to decelerate the motor vehicle (1) is provided at least in short time and is set to a target value, and an operating element (7); an operating element (7) is provided, by means of which a predetermined value for the regenerative torque can be selected from a plurality of predetermined values, a target value is determined in a first regenerative operating mode depending on the predetermined value, and a target value is determined in a second regenerative operating mode depending on the driving speed of the motor vehicle (1), and if a predetermined value corresponding to a non-zero regenerative torque is selected at the operating element (7), the target value is determined. If yes, executing a first regeneration operation mode. According to the invention, if a predetermined value corresponding to the zero regenerative torque is selected on the operating element (7) and an accelerator pedal (8) of the motor vehicle (1) is additionally actuated, a transition from the first regenerative operating mode to the second regenerative operating mode is made. The invention also relates to a motor vehicle (1).

Description

Technical Field

[0001] The invention relates to a method for operating a motor vehicle, the motor vehicle having: at least one electric machine, by means of which a regenerative torque intended to decelerate the motor vehicle is provided at least temporarily and is set to a target value; and an operating element, by means of which a preset value for the regenerative torque can be selected from a plurality of preset values, wherein in a first regenerative operating mode the target value is determined as a function of the preset value, and in a second regenerative operating mode the target value is determined as a function of the driving speed of the motor vehicle, wherein the first regenerative operating mode is executed if a preset value corresponding to a non-zero regenerative torque is selected on the operating element. The invention also relates to a motor vehicle. Background Art

[0002] From document EP 3 150 423 A1, a regenerative braking control device for a vehicle is known, which is designed to operate a rotating electric motor, which is designed to drive wheels at a regeneration ratio corresponding to a selected regeneration level so as to obtain a regenerative braking force. The regenerative braking control device has: a selection part, which is manually operated to select a regeneration level from a plurality of set regeneration levels; and a control part, which is designed to perform control so that when a predetermined operation is performed at the selection part, the regeneration level at which the predetermined operation is not performed at the selection part is automatically changed to another regeneration level. Summary of the invention

[0003] The object of the present invention is to provide a method for operating a motor vehicle which has advantages over the prior art in that, in particular, a reliable and flexible regenerative operation of the motor vehicle is possible.

[0004] According to the invention, this object is achieved by a method for operating a motor vehicle having the features of claim 1. It is provided that a changeover from a first regenerative operating mode to a second regenerative operating mode occurs when a preset value corresponding to zero regenerative torque is selected on an operating element and an accelerator pedal of the motor vehicle is additionally actuated.

[0005] Advantageous embodiments of the invention with suitable developments are given in the dependent claims. It should be pointed out that the exemplary embodiments described in the description are non-limiting; rather, any modifications of the features disclosed in the description, the claims and the drawings are possible.

[0006] The motor vehicle has at least one electric machine, which is preferably part of a power unit of the motor vehicle. The power unit serves to drive the motor vehicle, and therefore to provide a drive torque intended to drive the motor vehicle. The electric machine is provided, for example, as a power unit of the power unit. In addition to the electric machine, the power unit may have one or more further power units, for example one or more further electric machines and / or an internal combustion engine. The one or more power units are at least temporarily coupled to at least one wheel axle of the motor vehicle in terms of drive technology. In this regard, the motor vehicle can be driven at least temporarily by means of the at least one electric machine.

[0007] The drive torque can be provided for accelerating the motor vehicle as well as for decelerating the motor vehicle. Thus, the driving speed of the motor vehicle can be increased or decreased by means of the power unit. In order to decelerate the motor vehicle, a regenerative torque is provided at least temporarily by means of the electric machine. A regenerative torque is to be understood as a drive torque generated by the electric machine and intended to decelerate the motor vehicle. This is accomplished by the electric machine converting the kinetic energy of the motor vehicle into electrical energy. Thus, the electric machine is used at least temporarily in the regenerative mode as a regenerative brake in order to decelerate the motor vehicle.

[0008] It should be noted that the motor vehicle does not have to be decelerated exclusively by means of the electric machine during the regenerative mode, but it can of course be arranged in this way. Rather, the motor vehicle can additionally be decelerated by means of the service brakes of the motor vehicle, for example by using the wheel brakes assigned to at least one axle, and / or by means of one of the other power units, if present. In other words, during the regenerative mode, the motor vehicle is decelerated at least partially or completely by means of the electric machine.

[0009] The regenerative torque provided by the electric machine during the regenerative operation is set to a target value. This is preferably achieved by means of corresponding control of the electric machine power electronics. Preferably, the regenerative torque is regulated or regulated to the target value. By correspondingly selecting the target value, the regenerative torque and thus the deceleration of the motor vehicle caused by the electric machine can be set.

[0010] The motor vehicle further comprises an operating element, by means of which a preset value for the regeneration torque can be selected from a plurality of preset values. Preferably, the plurality of preset values ​​respectively correspond to different regeneration torques, so that different preset values ​​for the regeneration torque can be selected at the operating element. In this regard, the deceleration caused during the regeneration operation can be set or selected by means of the operating element.

[0011] It is provided that at least one of the plurality of preset values ​​corresponds to zero regeneration torque. For example, the first preset value corresponds to zero regeneration torque, and the second preset value corresponds to a non-zero regeneration torque. Preferably, the second preset value corresponds to a regeneration torque greater than zero. Particularly preferably, the plurality of preset values ​​further include other preset values ​​corresponding to gradually increasing regeneration torques.

[0012] The operating element is arranged in the interior space of the motor vehicle and exists, for example, in the form of one or more switching rockers on the steering wheel of the motor vehicle and / or as a selection lever. Additionally or alternatively, the operating element exists in the form of a multifunctional screen, which is, for example, a component of an instrument panel and / or a driver assistance device. A preset value can be selected from a plurality of preset values ​​by correspondingly operating the operating element. For example, it is provided that a gradually increasing or decreasing preset value of the regenerative torque can be selected by gradually operating the operating element. In this regard, the preset value can be gradually increased starting from a first preset value corresponding to zero regenerative torque by gradually operating the operating element. Correspondingly, the preset value can gradually decrease starting from a second preset value or a higher preset value in the direction of the first preset value.

[0013] The regeneration operation is provided with at least two regeneration operation modes, namely, a first regeneration operation mode and a second regeneration operation mode. The regeneration operation mode is selected according to a preset value selected on the operating element. Obviously, it can also be provided that the regeneration operation can be turned off by means of the operating element, so that the regeneration operation is not performed at least temporarily in this respect.

[0014] In the first regeneration operating mode, it is provided that the target value is determined according to a preset value. In particular, the preset value is used as the target value in the first regeneration operating mode. For example, the target value is set in such a way that the regeneration torque provided by the electric machine is set or adjusted to a regeneration torque corresponding to the preset value. Therefore, in the first regeneration operating mode, the target value of the regeneration torque is predetermined by means of the operating element.

[0015] Therefore, in the first regenerative operating mode, the motor vehicle decelerates with a predetermined regenerative torque, which is in particular manually predetermined by the motor vehicle driver by means of an operating element. In the first regenerative operating mode, the following driving behavior is reproduced by setting the target value in relation to the preset value, that is, it is similar to the driving behavior of a motor vehicle with an internal combustion engine in towing operation. In such a motor vehicle, the internal friction torque of the internal combustion engine produces a braking effect and thus causes the deceleration of the motor vehicle in towing operation, which is also called engine braking. In electrically driven motor vehicles, in particular in motor vehicles that can only be driven electrically, there is no corresponding internal friction torque of the internal combustion engine. In the first regenerative operating mode, the braking effect is reproduced by means of an electric machine. Therefore, in the first regenerative operating mode, the driving behavior of the motor vehicle is similar to the driving behavior of a motor vehicle with an internal combustion engine in towing operation. In particular, the enhanced braking effect of the transmission brake is reproduced by gradually increasing the preset value accordingly by means of an operating element, which occurs for a motor vehicle with an internal combustion engine in towing operation when the transmission gradually downshifts.

[0016] It is provided that if a preset value corresponding to a non-zero regenerative torque is selected on the operating element, a first regenerative operating mode is executed. In particular, if a preset value corresponding to a regenerative torque greater than zero is selected on the operating element, the first regenerative operating mode is executed. Thus, in the first regenerative operating mode, the target value corresponds at least temporarily to a non-zero regenerative torque. This is particularly the case as long as the accelerator pedal of the motor vehicle is not actuated, i.e., in this respect, as long as the driver does not have an explicit desire to accelerate and / or brake.

[0017] In the second regeneration operating mode, however, it is provided that a target value is determined according to the driving speed of the motor vehicle. Therefore, in the second regeneration operating mode, the target value of the regeneration torque is determined independently of the preset value. Therefore, in the second regeneration operating mode, the regeneration torque is not manually predetermined, but is determined automatically. For example, the target value is set in such a way that the driving speed of the motor vehicle matches the driving speed of other vehicles traveling ahead and / or the route direction. The motor vehicle is preferably equipped with corresponding devices to identify other vehicles traveling ahead and / or the route direction. Matching the driving speed with the route direction should be understood in particular as reducing the driving speed if it is appropriate in view of the route direction. For example, in the second regeneration operating mode, when the motor vehicle approaches a curve, a road intersection and / or a closed residential area, the driving speed is reduced in advance. The information about the route direction required for this purpose is provided, for example, by the driving assistance device.

[0018] It has already been pointed out that in the first regenerative operating mode, the target value is set according to the preset value as long as the accelerator pedal is not actuated, that is, in this respect the driver has no explicit acceleration and / or braking desire. If the accelerator pedal is actuated, however, it is provided that the target value is no longer set according to the preset value. In particular, it is provided that when the accelerator pedal is actuated during the execution of the first regenerative operating mode, the first regenerative operating mode is interrupted at least briefly in order to set the drive torque and / or the braking force of the service brake as required according to the acceleration and / or braking desire of the driver. It is obvious that it can be provided here that the regenerative torque provided by the electric machine is additionally or alternatively used in order to generate the braking force.

[0019] If the accelerator pedal is actuated during the execution of the first regenerative operating mode and the first regenerative operating mode is thus interrupted, it can be provided that, once it is determined that the accelerator pedal is no longer actuated, a transition to the second regenerative operating mode or no longer regenerative operation is performed. Surprisingly, however, this approach is often considered undesirable by the driver. Therefore, it is provided that, once it is determined that the accelerator pedal is no longer actuated, the first regenerative operating mode is continued after the interruption. As long as a preset value corresponding to a non-zero regenerative torque is selected on the operating element and the accelerator pedal is not actuated, the first regenerative operating mode is continued.

[0020] According to the invention, it is provided that if a preset value corresponding to zero regenerative torque is selected on the operating element and the accelerator pedal of the motor vehicle is additionally actuated, a change is made from the first regenerative operating mode to the second regenerative operating mode. In particular, the accelerator pedal must be actuated at least briefly within a certain time period after the selection of the preset value corresponding to zero regenerative torque in order to change to the second regenerative operating mode. On the other hand, if the accelerator pedal is not actuated within a certain time period, the selection of the preset value is preferably canceled and the first regenerative operating mode is continued using the previously selected preset value instead.

[0021] Therefore, in order to switch to the second regenerative operating mode, it is not sufficient to simply select a preset value corresponding to zero regenerative torque on the operating element. Instead, the accelerator pedal must be additionally actuated in order to switch to the second regenerative operating mode. Conversely, in the first regenerative operating mode, it is also not sufficient to simply actuate the accelerator pedal in order to interrupt the first regenerative operating mode and switch to the second regenerative operating mode. Instead, in order to switch from the first regenerative operating mode to the second regenerative operating mode, a preset value corresponding to zero regenerative torque must be additionally selected on the operating element.

[0022] This allows for a particularly reliable and flexible regenerative operation. Thus, on the one hand, after a brief actuation of the accelerator pedal, the first regenerative operating mode is only continued if a preset value corresponding to zero regenerative torque is set on the operating element. This corresponds to the behavior desired by the driver, since, for example, after a brief acceleration or braking of the vehicle by actuation of the accelerator pedal, the first regenerative operation is continued and not terminated.

[0023] On the other hand, an unintentional changeover to the second regenerative operating mode is avoided if a preset value corresponding to zero regenerative torque is inadvertently selected on the operating element in the first regenerative operating mode. In this case, if a changeover is made to the second regenerative operating mode, this can lead to undesirable driving behavior, since the regenerative torque is no longer set in the second regenerative operating mode in relation to the preset value. Therefore, provision is made for a changeover to the second regenerative operating mode to take place only when the changeover is additionally determined by actuating the accelerator pedal.

[0024] An improved solution of the present invention provides that in the first regeneration operating mode, the target value is additionally set in relation to the driving speed. Therefore, it is provided that the target value is determined in relation to a preset value and in relation to the driving speed. In particular, the target value is increased in relation to the driving speed and exceeds the preset value. For example, it is provided that in the case of a first, smaller driving speed, which is preferably greater than zero, a smaller first target value is selected as the target value, and in the case of a second, larger driving speed, a larger second target value is selected as the target value. Preferably, at least the larger second target value is greater than the preset value. Of course, both the smaller first target value and the larger second target value may be correspondingly greater than the preset value. In other words, in the first regeneration operating mode, the regeneration torque has a speed-dependent component, which increases as the driving speed increases. This results in a particularly flexible regeneration operation, because at higher driving speeds, the braking effect of the regeneration operation is correspondingly greater.

[0025] Additionally or alternatively, it is provided that if the regenerative torque corresponding to the selected preset value is not sufficient to adapt the driving speed to the driving speed of the vehicle ahead and / or the route, the target value is increased by more than the preset value. In other words, the speed-dependent component of the regenerative torque is adjusted in advance to match the driving speed and / or the route of the vehicle ahead by more than the preset value. This results in a particularly efficient and reliable regenerative operation.

[0026] The improvement of the present invention provides that the target value is set in such a way that the driving speed is set to the target driving speed. When the target value is set additionally as a function of the driving speed, this is preferably set in the second regeneration operating mode and in the first regeneration operating mode. Alternatively, this is set only in the second regeneration operating mode. The target driving speed is to be understood as a driving speed that the motor vehicle should not exceed and / or should not fall below. The target value is set in such a way that the driving speed of the motor vehicle is set in the direction of the target driving speed or the driving speed of the motor vehicle is adjusted to the target driving speed.

[0027] Preferably, it is provided that the motor vehicle is decelerated by means of a regenerative torque provided by the electric machine when the driving speed is greater than the target driving speed. Particularly preferably, this is achieved exclusively by means of the regenerative torque. For this purpose, a target value is set accordingly in order to reduce the driving speed to the target driving speed, but not below the target driving speed. Conversely, it is preferably provided that the regenerative torque is reduced when the driving speed is less than the target driving speed. This applies in particular when the route has a downhill slope. In this way, a particularly reliable regenerative operation is achieved, because the driving speed is always adjusted in the direction of the target driving speed.

[0028] A refinement of the invention provides that the target driving speed is determined by a setting of the operating element and / or by the driver assistance device. The target driving speed can be set, for example, by means of the operating element and in this respect can be predetermined by the driver. For this purpose, the operating element has a setting that can be used to set the target driving speed. For example, the target driving speed can be freely selected on the operating element. Preferably, the operating element is designed to use the currently existing driving speed as the target driving speed. This enables a particularly flexible regeneration operation.

[0029] Additionally or alternatively, the target driving speed is determined by a driver assistance device. The driver assistance device, for example, has a corresponding data item in which the target driving speed is stored. The data item is, for example, map information of a navigation device. Additionally or alternatively, the driver assistance device has a traffic sign recognition device, which is designed to determine the target driving speed based on traffic signs arranged along the route. This enables a particularly reliable regeneration operation.

[0030] A further development of the invention provides that the inclination / pitch angle of the motor vehicle is determined and the target value is also set in dependence on the inclination angle. The inclination angle is understood in particular to be the inclination angle of the longitudinal center line of the motor vehicle arranged in the direction of travel, in particular relative to a geodetic coordinate system.

[0031] The inclination angle corresponds approximately to an upslope or downslope of the roadway on which the motor vehicle is moving. For example, a positive inclination angle corresponds to an upslope and a negative inclination angle corresponds to a downslope. Provision is made for the target value to be increased in the case of a positive inclination angle and / or for the target value to be reduced in the case of a negative inclination angle. Accordingly, the target value is increased in the case of a positive inclination angle or reduced in the case of a negative inclination angle. This enables a particularly flexible regenerative operation, since the braking action is adapted to the upslope or downslope.

[0032] The improvement of the invention provides that if the driving speed is greater than the target driving speed, the target value is determined in relation to other preset values ​​of the regeneration torque. Preferably, this is achieved in the case of a third regeneration operating mode, which can be set in combination with the first regeneration operating mode and / or the second regeneration operating mode or can be set independently of the first regeneration operating mode and the second regeneration operating mode.

[0033] In the third regeneration operating mode, if the driving speed exceeds the target driving speed, the target value is no longer determined according to the preset value and / or the driving speed, but is determined according to another preset value that is preferably greater than the preset value. Preferably, in the third regeneration operating mode, a greater regeneration torque is provided at least temporarily than in the first regeneration operating mode and / or in the second regeneration operating mode.

[0034] In particular, the third regeneration operating mode is executed after the target driving speed has been changed, in particular to a lower target driving speed, for example by means of an operating element and / or by a driver assistance device. The third regeneration operating mode is executed until the driving speed corresponds to the target driving speed. In other words, the third regeneration operating mode is executed in order to increase the regeneration torque briefly after the target driving speed has been changed so that it exceeds the regeneration torque provided in the first regeneration operating mode and / or the second regeneration operating mode.

[0035] Then, as long as the third regeneration operating mode is executed in combination with the first operating mode and the second operating mode, the first regeneration operating mode and / or the second regeneration operating mode is continued. Alternatively, the regeneration operation is terminated. This approach enables a particularly flexible regeneration operation, in which the driving speed is matched to the changed target driving speed in a particularly effective manner.

[0036] A refinement of the invention provides that the further preset value is selected from a plurality of preset values. For example, the further preset value can be selected from a plurality of preset values ​​on the operating element. Thus, at least two preset values ​​can be selected on the operating element, namely the preset value and the further preset value. The preset value and the further preset value can be selected independently of one another from a plurality of preset values. Additionally or alternatively, the further preset value can be freely selected.

[0037] The other preset value is preferably always greater than the preset value, as has been pointed out above. It can be seen from this that the preset value corresponding to zero regeneration torque cannot be selected as the other preset value. Therefore, the other preset value always corresponds to a regeneration torque greater than zero. This ensures that sufficient regeneration torque is always provided in the third regeneration operating mode in order to reduce the driving speed to the target driving speed.

[0038] A further development of the invention provides that a driving speed difference between the motor vehicle and the vehicle travelling ahead is determined, and the target driving speed is set as a function of the driving speed difference. The vehicle travelling ahead has already been mentioned above.

[0039] For example, the speed difference is determined with the aid of a driver assistance device. If the speed difference is greater than zero, i.e. the speed of the motor vehicle is greater than the speed of the vehicle ahead, the distance between the motor vehicle and the vehicle ahead is reduced accordingly. Accordingly, it is provided that the target speed is set so that a speed difference of zero occurs. Additionally or alternatively, the target speed is adjusted such that the distance is adjusted to a predetermined distance. In any case, as long as the speed difference is greater than zero, the target speed is selected to be different from the target speed determined by the setting of the operating element and / or the target speed determined by the driver assistance device.

[0040] On the other hand, if the speed difference is less than zero, i.e. the speed of the motor vehicle is less than the speed of the vehicle ahead, the target speed is set independently of the speed difference. In this case, for example, a target speed determined by the setting of the operating element and / or a target speed determined by the driver assistance device is used. This enables a particularly flexible regeneration operation.

[0041] A refinement of the invention provides that the target value is set as a function of the charge state of an energy storage device connected to the electric machine. The energy storage device is present, for example, as a power battery, by means of which electrical energy for the electric machine is provided or temporarily stored. Alternatively, in addition to the power battery, an energy storage device may also be present, for example in the form of a buffer storage device present as a capacitor.

[0042] During the regenerative operation, kinetic energy is converted into electrical energy by means of the electric machine. The electrical energy is at least partially, preferably completely, supplied to the energy accumulator. The state of charge of the energy accumulator indicates its capacity. It is therefore provided that the target value is set as a function of the capacity of the energy accumulator. For example, it is provided that the target value is adjusted in the direction of a zero value if it is determined based on the state of charge that the capacity of the energy accumulator is no longer sufficient to absorb the electrical energy provided by the electric machine. In particular, a target value of zero is used if the energy accumulator is fully charged. Preferably, in this case, the regenerative operation is terminated or at least briefly interrupted. This enables a particularly reliable regenerative operation.

[0043] The invention also relates to a motor vehicle, in particular for carrying out a method according to an embodiment of the present description, the motor vehicle having: at least one electric machine, by means of which a regenerative torque intended to decelerate the motor vehicle is provided at least temporarily and a target value is set; and an operating element, by means of which a preset value of the regenerative torque can be selected from a plurality of preset values, wherein the motor vehicle is designed and constructed such that in a first regenerative operating mode the target value is determined as a function of the preset value, and in a second regenerative operating mode the target value is determined as a function of the driving speed of the motor vehicle, wherein the first regenerative operating mode is executed if a preset value corresponding to a non-zero regenerative torque is selected on the operating element. It is provided that the motor vehicle is also designed and constructed such that a transition is made from the first regenerative operating mode to the second regenerative operating mode if a preset value corresponding to a zero regenerative torque is selected on the operating element and an accelerator pedal of the motor vehicle is additionally actuated.

[0044] The advantages of this embodiment of the motor vehicle have already been pointed out. The motor vehicle and the method for operating a motor vehicle can be developed according to the embodiments in the present description, so that reference is made to these embodiments in this regard.

[0045] The features and combinations of features described in the specification, in particular the features and combinations of features described in the following description of the figures and / or shown in the figures, can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the present invention. Therefore, embodiments that are not explicitly shown or explained in the specification and / or the figures, but are derived from or can be derived from the feature combinations of the described embodiments, are also considered to be covered by the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The invention is explained in greater detail below with reference to an exemplary embodiment shown in the drawing, without however restricting the invention.

[0047] in:

[0048] Figure 1 A schematic diagram of a motor vehicle is shown. DETAILED DESCRIPTION

[0049] Figure 1 A motor vehicle 1 is shown, which has a power unit 2 having an electric machine 3. The electric machine 3 is coupled to at least one axle 4 of the motor vehicle 1 for drive technology at least temporarily. In a regenerative mode, a regenerative torque is provided at least temporarily by means of the electric machine 3, which is intended to decelerate the motor vehicle 1. In this case, kinetic energy is converted into electrical energy by means of the electric machine 3. The electrical energy is preferably supplied to an energy storage device 5 connected to the electric machine 3.

[0050] The motor 3 is set or regulated to a target value during the regeneration operation by means of the controller 6. The motor vehicle 1 has at least one operating element 7 and at least one accelerator pedal 8. The operating element 7 is, for example, a switch rocker, a selector lever and / or a multifunction display arranged on the steering wheel. The drive torque provided by the power device 2 can be influenced by means of the accelerator pedal 8. Alternatively, the accelerator pedal 8 is provided as a brake pedal, which is present in addition to another accelerator pedal.

[0051] The preset value for the regenerative torque can be selected from a plurality of preset values ​​by means of the operating element 7. The plurality of preset values ​​include: a first preset value, which corresponds to zero regenerative torque; and at least one second preset value, which corresponds to a non-zero regenerative torque. Preferably, the preset value can be selected by stepwise manipulation of the operating element 7, wherein the preset value of the regenerative torque is gradually increased or decreased.

[0052] At least two operating modes are provided within the scope of the regeneration operation. In the first regeneration operating mode, the target value is determined according to a preset value. In the first regeneration operating mode, in particular, the target value is set or adjusted to a preset value. In this regard, in the first regeneration operating mode, the regeneration torque is set to a preset value selected by means of the operating element 7.

[0053] In the second regeneration operating mode, a target value is set as a function of the driving speed of the motor vehicle 1. In this regard, in the second regeneration operating mode, the regeneration torque is not set to a preset value. Instead, the target value is set automatically independently of the preset value. For example, the target value is set such that the driving speed is set to a target driving speed. For example, the target driving speed is determined as a function of the setting of the operating element 7. Additionally or alternatively, the target driving speed is determined by a driving assistance device not further shown. Preferably, the target driving speed is set as a function of the driving speed of the vehicle ahead and / or is matched to the route course.

[0054] The changeover between the first regeneration operating mode and the second regeneration operating mode occurs as a function of the preset value selected by means of the operating element 7. Thus, it is provided that the first regeneration operating mode is executed if a preset value corresponding to a non-zero regeneration torque is selected at the operating element 7.

[0055] It is further provided that if a preset value corresponding to zero regenerative torque is selected on the operating element 7 and the accelerator pedal 8 is additionally actuated, a transition from the first regenerative operating mode to the second regenerative operating mode occurs. Therefore, in order to transition to the second regenerative operating mode, it is not sufficient to select a corresponding preset value on the operating element 7. For this purpose, the accelerator pedal 8 must be additionally actuated at least briefly. In particular, it is provided that the selection of the preset value corresponding to zero regenerative torque on the operating element 7 is canceled if the accelerator pedal 8 is not actuated at least briefly within a defined time period after the selection of the preset value.

[0056] If the accelerator pedal 8 is operated during the regeneration operation, for example to brake or accelerate the motor vehicle, it can be provided that the regeneration operation is interrupted at least briefly. Subsequently, as soon as the accelerator pedal 8 is no longer operated, the regeneration operation is continued in the previously selected regeneration operation mode. Thus, after the regeneration operation is briefly interrupted due to the operation of the accelerator pedal 8 in the first regeneration operation mode, the first regeneration operation mode is still continued.

[0057] In addition, a third regeneration operating mode is provided. For this purpose, another preset value of the regeneration torque can be selected on the operating element 7, which corresponds to a higher regeneration torque than the preset value. If the driving speed exceeds the target driving speed, the third regeneration operating mode is executed. Here, the target value is determined according to another preset value. In particular, the target value is set to another preset value until the driving speed reaches the target driving speed. Then, the first regeneration operating mode or the second regeneration operating mode is switched. Alternatively, if the driving speed is less than the target driving speed, the regeneration operation is terminated.

[0058] List of reference numerals:

[0059] 1 Motor Vehicle

[0060] 2 Power equipment

[0061] 3 Motor

[0062] 4 Axles

[0063] 5 Accumulator

[0064] 6 Controller

[0065] 7 Operating elements

[0066] 8 Accelerator pedal

Claims

1. A method for operating a motor vehicle (1), the motor vehicle having: at least one electric machine (3), by means of which a regenerative torque is provided at least temporarily for decelerating the motor vehicle (1) and the regenerative torque is set to a target value; an operating element (7), by means of which a preset value for the regenerative torque can be selected from a plurality of preset values, in, In a first regeneration operating mode, the target value is determined according to a preset value, and in a second regeneration operating mode, the target value is determined according to the driving speed of the motor vehicle (1), wherein the first regeneration operating mode is executed if a preset value corresponding to a non-zero regeneration torque is selected on the operating element (7), The invention is characterized in that a change is made from the first regenerative operating mode to the second regenerative operating mode if a preset value corresponding to zero regenerative torque is selected on the operating element (7) and an accelerator pedal (8) of the motor vehicle (1) is additionally actuated.

2. The method according to claim 1, characterized in that In the first regeneration operating mode, the target value is additionally set as a function of the driving speed.

3. The method according to any one of the preceding claims, characterized in that The target value is set so that the traveling speed is set to the target traveling speed.

4. The method according to any one of the preceding claims, characterized in that The target driving speed is determined as a function of a setting of an operating element (7) and / or by a driver assistance device.

5. The method according to any one of the preceding claims, characterized in that The tilt angle of the vehicle (1) is determined, and a target value is set according to the tilt angle.

6. The method according to any one of the preceding claims, characterized in that If the driving speed is greater than the target driving speed, the target value is determined according to another preset value for the regenerative torque.

7. The method according to any one of the preceding claims, characterized in that The another preset value is selected from a plurality of preset values.

8. The method according to any one of the preceding claims, characterized in that A driving speed difference between a motor vehicle (1) and a vehicle traveling ahead is determined, and a target driving speed is set based on the driving speed difference.

9. The method according to any one of the preceding claims, characterized in that The target value is set according to the charge state of an energy storage device (5) connected to the motor (3).

10. A motor vehicle, in particular for executing a motor vehicle according to any one or more of the preceding claims, comprising: at least one electric motor (3) and an operating element (7), by means of which a regenerative torque is provided at least temporarily for decelerating the motor vehicle (1) and the regenerative torque is set to a target value; by means of the operating element a preset value for the regenerative torque can be selected from a plurality of preset values, wherein: The motor vehicle (1) is designed and constructed so that in a first regeneration operating mode a target value is determined according to a preset value, and in a second regeneration operating mode a target value is determined according to a driving speed of the motor vehicle (1), wherein the first regeneration operating mode is executed if a preset value corresponding to a non-zero regeneration torque is selected on an operating element (7), and the motor vehicle is also designed and constructed so that a transition is made from the first regeneration operating mode to the second regeneration operating mode if a preset value corresponding to a zero regeneration torque is selected on the operating element (7) and an accelerator pedal (8) of the motor vehicle (1) is additionally actuated.

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