WO2024099705A1

WO2024099705A1 - Method and device for coupling an electric machine

Info

Publication number: WO2024099705A1
Application number: PCT/EP2023/078730
Authority: WO
Inventors: Jens Halbedel; Henry KRUEGER; Christian Karges
Original assignee: Bayerische Motoren Werke Aktiengesellschaft
Priority date: 2022-11-08
Filing date: 2023-10-17
Publication date: 2024-05-16
Also published as: DE102022129429A1

Abstract

A device for coupling a second electric machine to a wheel of a vehicle by means of a decoupling unit, while the vehicle is already being driven by a first electric machine. The device is configured to determine that the second electric machine is to be coupled to the wheel of the vehicle. The device is also configured to cause at least one presentation measure in response to the determination, by which the coupling of the second electric machine is made perceptible to a user of the vehicle.

Description

Method and device for coupling an electrical machine

The invention relates to a method and a corresponding device designed to couple an electrical machine to an axle of a motor vehicle.

An electrically powered motor vehicle may comprise one or more electrical machines that are permanently connected to an axle, e.g. the front axle or the rear axle, of the vehicle in order to drive the axle and thus the vehicle.

In a four-wheel drive vehicle, the two axles of the vehicle are typically each driven by a dedicated set of electrical machines. A decoupling unit can be arranged between at least one axle and the respective set of electrical machines in order to selectively decouple the set of electrical machines from the axle, e.g. if four-wheel operation is not required and/or desired to drive the vehicle.

The decoupling unit can have a dead time in order to couple the set of electrical machines to the axle and then to cause a drive torque on the axle. This dead time and the resulting, possibly smoothed, build-up of the additional drive or torque can be perceived by a user of the vehicle as uncomfortable and/or sluggish or unsporting.

This document deals with the technical task of efficiently increasing the comfort and/or sportiness of a vehicle when connecting an electric machine to the vehicle.

The problem is solved by each of the independent claims. Advantageous embodiments are described, among other things, in the dependent claims. It is pointed out that additional features of a patent claim dependent on an independent patent claim can form a separate invention without the features of the independent patent claim or only in combination with a subset of the features of the independent patent claim, which invention is independent of the combination of all features of the independent patent claim and can be made the subject of an independent claim, a divisional application or a subsequent application. This applies equally to technical teachings described in the description, which can form an invention independent of the features of the independent patent claims.

According to one aspect, a device for coupling a second electric machine by means of a decoupling unit (in particular by means of a clutch, e.g. by means of a claw clutch) to a wheel of a (motor) vehicle is provided. The vehicle can already be driven by a first electric machine driven. The first electric machine can be designed to drive a first axle of the vehicle and the second electric machine can be designed to drive a second axle of the vehicle (on which the at least one wheel of the vehicle to be driven is arranged). The first axle can be the front axle and the second axle can be the rear axle of the vehicle. Alternatively, the first axle can be the rear axle and the second axle can be the front axle.

The decoupling unit can be designed to decouple the second electric machine from the (driven) wheel, in particular from the second axle, in the open state. Furthermore, the decoupling unit can be designed to couple the second electric machine to the wheel, in particular to the second axle, in the closed state, so that the wheel and/or the second axle are driven by the second electric machine (if a torque is generated by the second electric machine).

The vehicle can thus have a (purely) electric all-wheel drive, in which the second electric machine can be decoupled from the second axle of the vehicle if necessary (by the decoupling unit) (in order to enable the vehicle to operate as efficiently as possible). On the other hand, the second electric machine can be coupled to the second axle again (e.g. to provide an increased drive torque of the vehicle).

The device is configured to determine that the second electric machine should be coupled to the wheel of the vehicle. For example, it can be recognized that an additional drive torque (in addition to the drive torque provided by the first electric machine) is required to drive the vehicle, which (after coupling) can be provided by the second electric machine. The vehicle can comprise a dedicated control element, in particular a shift paddle (on the steering wheel) and/or a kick-down pedal and/or a control knob or a control button (which enables the user, in particular the driver, of the vehicle to explicitly request the coupling of the second electric machine). The device can be set up to detect an actuation of the control element. It can then be determined based on the detected actuation that the second electric machine should be coupled to the wheel of the vehicle. Furthermore, the coupling of the second electric machine (via the (closed) decoupling unit) to the wheel of the vehicle can then be effected. By providing a dedicated control element for requesting the coupling of the second electric machine, a particularly convenient coupling of the second electric machine can be effected.

In particular, by providing a dedicated control and/or operating element, it can be made possible to transfer the coupling unit to the closed state (in order to couple the second electric machine to the wheel, in particular to the second axle) even before the user of the vehicle requests additional power via the vehicle's accelerator pedal (e.g. to initiate an overrun process). A torque and/or power build-up (by the second machine) can then be brought about without delay (in response to the actuation of the accelerator pedal).

The device can further be configured to effect at least one staging measure in response to the determination, by means of which the coupling of the second electric machine becomes perceptible to the user, in particular to the driver, of the vehicle.

For example, it can be determined at a detection point in time that the second electric machine should be coupled to the wheel (in particular to the second axle) of the vehicle. Furthermore, at a subsequent coupling At this point in time, the device can cause the second electric machine to be coupled to the wheel (in particular to the second axle) of the vehicle via the decoupling unit. This can be brought about by closing the decoupling unit.

The device can be configured to prepare the staging measure between the detection time and the coupling time in such a way that at the coupling time the coupling of the second electric machine becomes perceptible to the user of the vehicle, in particular by an additional vehicle acceleration and/or by an (additional and/or modified) noise and/or by an (additional and/or modified) graphic display.

The actual coupling of the second electric machine to the wheel, in particular to the second axle, of the vehicle can, for example, cause a basic acceleration and/or a basic jolt and/or a basic noise and/or a basic display. These can be designed in such a way that they are perceived by the user as relatively weak and/or disturbing and/or not at all. The at least one staging measure can be aimed at (at the coupling time)

• to cause a staging acceleration that exceeds the base acceleration (e.g. by 10% or more); and/or

• to cause a staging jolt that exceeds the base jolt (e.g. by 10% or more); and/or

• to create a staging noise that exceeds the base noise (e.g. by 10% or more);

• to create a staged display that differs from the basic display (e.g. through (additional and/or modified) animation and/or coloring and/or graphic elements of the display). The staging acceleration and/or the staging jolt and/or the staging noise and/or the staging display can be so strong that they are perceived by the user as a driving experience.

This makes it possible to create an explicit, additionally perceptible, staging of the coupling of the second electric machine, e.g. to increase the comfort of the vehicle in an efficient manner.

The device can be set up to cause, as part of a staging measure, that a torque produced by the first electric machine is reduced before the coupling time, in particular by a torque reserve. For example, a target torque can be provided by the first electric machine at the detection time. The device can cause the torque produced by the first electric machine (up to the coupling time) to be reduced to a reduced torque in order to generate a torque reserve. The reduced torque can be 5% or more below the target torque, for example.

The device can also be designed to cause the torque produced by the first electric machine to be increased again, in particular by the torque reserve, at the coupling point in time at which the coupling of the second electric machine takes place. In this way, a staging of the coupling of the second electric machine that is perceptible (as a driving experience) can be brought about in a particularly efficient manner.

The device can be set up to reduce the torque produced by the first electrical machine starting from the detection time up to the coupling time, in particular smoothly (and thus not perceptible to the user). Furthermore, the device can be set up to cause the torque produced by the first electrical machine at the coupling point is suddenly increased, especially by the torque reserve. This allows a particularly comfortable staging of the coupling.

Alternatively or additionally, the device can be set up to cause, as part of a staging measure, the speed of the second electric machine to be increased to an excessive speed before the coupling time, which is greater than the target speed of the second electric machine for the coupling. The target speed can depend on the current speed of the wheel of the vehicle.

The device can be configured to determine the current rotational speed of the wheel (at the time of detection). Based on this, the target rotational speed of the second electric machine for the coupling can be determined, e.g. so that the target rotational speed corresponds to the current rotational speed of the wheel (taking into account the gear ratio between the shaft of the second electric machine and the wheel axle of the wheel).

The second electric machine can be caused to be set (between the detection time and the coupling time) to an excessive speed that is, for example, 5% or more higher than the target speed.

In particular, the speed of the second electric machine can be increased to the excessive speed starting from the detection time up to the coupling time.

Furthermore, at the coupling time, the second electric machine can be coupled to the wheel of the vehicle via the decoupling unit. Due to the excessive speed of the second electric machine and due to the inertia of the shaft of the second electric machine, an effect perceptible to the user is achieved, in particular with regard to additional vehicle acceleration and/or with regard to a noise by means of one or more several loudspeakers and/or a graphic representation using one or more screens of a display operating concept of the vehicle. This can create a particularly comfortable and/or sporty staging of the coupling of the second electric machine.

The device can be set up to cause, as part of a staging measure, that a centrifugal force unit (e.g. a flywheel), in particular by the second electric machine, is driven before the coupling time. Furthermore, at the coupling time, the second electric machine and the driven centrifugal force unit can be coupled to the wheel of the vehicle via the decoupling unit, so that the driven centrifugal force unit produces an effect that is perceptible to the user, in particular in relation to additional vehicle acceleration and/or in relation to a noise by means of one or more loudspeakers and/or a graphic representation by means of one or more screens of a display operating concept of the vehicle. In this way, a particularly comfortable and/or sporty staging of the coupling can be achieved.

It should be noted that the one or more staging measures described in this document can be used in a corresponding manner to generate an additional (noticeable) deceleration of the vehicle (e.g. when the second electric machine is coupled to recuperate electrical energy from the kinetic energy of the vehicle).

The device can be set up in particular to determine that the second electric machine should be coupled to the wheel of the vehicle for recuperation. As part of a staging measure, it can then be ensured that before the coupling time the speed of the second electric machine is set to a reduced speed that is lower than the target speed of the second electric machine. The device can also be set up to cause the second electric machine to be coupled to the wheel of the vehicle via the decoupling unit at the coupling time, so that due to the reduced speed of the second electric machine and due to an inertia of a shaft of the second electric machine, an effect perceptible to the user is generated, in particular in relation to an additional vehicle deceleration and/or in relation to a noise by means of one or more loudspeakers and/or a graphic representation by means of one or more screens of a display operating concept of the vehicle. In this way, a particularly comfortable and/or sporty staging of the coupling can be achieved.

The device can be set up to determine the driving speed and/or the acceleration of the vehicle (e.g. the driving speed and/or the acceleration at the time of detection). The one or more staging measures can then be effected depending on the driving speed and/or the acceleration of the vehicle. In particular, the extent and/or the strength of the one or more staging measures, such as the level of the torque reserve of the first electric machine effected as part of a staging measure and/or the level of the excessive speed of the second electric machine effected as part of a staging measure, can be adjusted depending on the driving speed and/or the acceleration.

The device can be set up to bring about one or more staging measures if the driving speed is less than a speed threshold value and/or if the acceleration is less than an acceleration threshold value. Alternatively or additionally, the device can be set up not to bring about and/or to prevent one or more staging measures if the Driving speed is greater than the speed threshold value and/or when the acceleration is greater than the acceleration threshold value. Alternatively or additionally, the extent of the one or more measures, in particular the level of the torque reserve and/or the level of the excessive speed, can be reduced with increasing driving speed and/or with increasing acceleration and/or increased with decreasing driving speed and/or with decreasing acceleration.

The coupling of the second electric machine can therefore be initiated depending on the current driving speed and/or the current acceleration of the vehicle. This can, for example, further increase the comfort and/or driving experience of the vehicle.

Alternatively or additionally, the one or more staging measures can be implemented depending on one or more environmental conditions of the vehicle's surroundings. An example environmental condition is the coefficient of friction of the road on which the vehicle is driving. Alternatively or additionally, the one or more staging measures can be implemented or not implemented depending on data from a navigation system of the vehicle, e.g. depending on a type of road (such as motorway, country road, city street, play street, etc.) on which the vehicle is driving. In this way, for example, the comfort and/or driving experience of the vehicle can be further increased.

According to a further aspect, a (road) motor vehicle (in particular a passenger car or a truck or a bus or a motorcycle) is described which comprises the device described in this document.

According to a further aspect, a method for coupling a second electric machine by means of a decoupling unit (eg by means of a clutch) to at least one wheel of a (motor) vehicle, while the Vehicle is already driven by a first electric machine. The method includes determining that the second electric machine is to be coupled to the wheel of the vehicle. The method further includes, in response to the determining, effecting at least one staging action by which the coupling of the second electric machine becomes perceptible to a user of the vehicle.

According to a further aspect, a software (SW) program is described. The SW program can be configured to be executed on a processor (e.g. on a control unit of a vehicle) and thereby to carry out the method described in this document.

According to a further aspect, a storage medium is described. The storage medium can comprise a software program which is designed to be executed on a processor and thereby to carry out the method described in this document.

It should be noted that the methods, devices and systems described in this document can be used alone or in combination with other methods, devices and systems described in this document. Furthermore, any aspects of the methods, devices and systems described in this document can be combined with one another in a variety of ways. In particular, the features of the claims can be combined with one another in a variety of ways. Furthermore, features listed in brackets are to be understood as optional features.

The invention is described in more detail below using exemplary embodiments.

Figure 1 shows exemplary components of a vehicle;

Figure 2a shows an exemplary temporal progression of the rotational speed of an electrical machine during a coupling process; Figure 2b shows an exemplary temporal progression of the rotational and/or drive torque produced by an already coupled electrical machine during a coupling process of another electrical machine; and Figure 3 shows a flow chart of an exemplary method for coupling an electrical machine to an axle of a vehicle.

As stated at the beginning, the present document deals with increasing the comfort of a user when coupling an electric machine. In this context, Fig. 1 shows an exemplary vehicle 100 that includes a first electric machine 101 that is designed to drive a first axle 111 (e.g. the rear axle) of the vehicle 100. The first electric machine 101 can optionally be firmly coupled to the first axle.

The vehicle 100 further comprises a second electric machine 102, which is designed to drive a second axle 112 (e.g. the front axle) of the vehicle 100. Between the second electric machine 102 and the second axle 112, a decoupling unit 103 (e.g. a (claw) clutch) can be arranged, which is designed to selectively couple the second electric machine 102 to the second axle 112 or to decouple it therefrom.

The vehicle 100 may further comprise one or more control elements 104 that enable a user, in particular the driver, of the vehicle 100 to control the drive of the vehicle 100. Example control elements 104 are an accelerator pedal (e.g., a kick-down pedal) and/or a shift paddle.

The vehicle 100 shown in Fig. 1 is thus an all-wheel vehicle 100 in which all wheels of the vehicle 100 can be driven by one or more electric machines 101, 102 (indirectly via the axles 111, 112). In certain driving situations, it can be advantageous, particularly with regard to energy consumption, to decouple the second electric machine 102 from the second axle 112. This can be the case in particular if the first electric machine 101 can provide a sufficiently high torque to drive the vehicle 100 (e.g. during a steady highway journey).

A (control) device 110 of the vehicle 100 can detect and/or determine that the second electric machine 102 should be coupled to the second axle 112, e.g. to provide additional drive torque. The second electric machine 102 can then be activated and the speed of the second electric machine 102 can be adapted to the current driving speed of the vehicle 100 and/or to the current speed of the second axle 112. The second electric machine 102 can also be coupled to the second axle 112 via the decoupling unit 103 (in particular by closing the decoupling unit).

The coupling process caused by the decoupling unit 103 can have a certain dead time. This can lead to the torque caused by the second electric machine 102 being transmitted to the second axle 112 with a time delay and/or with a certain starting gradient (i.e., smoothed). This can be perceived as unpleasant by a user, in particular by the driver, of the vehicle 100. Furthermore, such a smoothed coupling of the second electric machine 102 requires the use of a relatively complex coupling within the decoupling unit 103, which is associated with additional costs and/or installation space and/or weight.

This document describes a method by which an active staging of the coupling process is effected, which is perceptible by the user, in particular by the driver, of the vehicle 100. As part of the staging, one or more staging measures can be effected, which at least partially lead to a structure perceptible to the driver. an additional rotational and/or drive torque (associated with the coupling process). This can increase comfort for the user. Furthermore, this can enable the use of a relatively cost-effective coupling, in particular a claw coupling, within the decoupling unit 103.

The (control) device 110 can, for example, recognize based on the actuation of a control element 104 of the vehicle 100 that the second electric machine 102 is to be coupled to the second axle 112. The control element 104 can, for example, be a shift paddle and/or a kick-down paddle. A control element 104 can thus be provided that explicitly enables the user of the vehicle 100 to initiate the coupling of the second electric machine 102.

As shown in Figures 2a and 2b, it can be recognized, for example, at a detection time 201 that the second electric machine 102 is to be coupled to the second axle 112. In response to this, the second electric machine 102 can be activated and accelerated (see Fig. 2a). In this case, for example, a target speed 211 can be determined for the second electric machine 102, which depends on the driving speed of the vehicle 100 and/or on the speed of the second axle 112. The target speed 211 can, for example, correspond to the speed of the second axle 112 (according to the gear ratio of an optional transmission of the decoupling unit 103).

As a staging measure, the second electric machine 102 can be accelerated to an excessive speed 212 that is higher than the target speed 211 before the coupling time 202 at which the coupling with the second axle 112 takes place. This is illustrated by the time profile 215 of the speed 210 shown in Fig. 2a (which shows the speed 210 of the second electric machine 102 as a function of time 200). The second electric machine 102 thus has an excessive speed 212 at the coupling time 202, which is above the target speed 211 by the offset value 213 (eg by 5% or more or by 10% or more). As a result, when the second electric machine 102 is coupled, an additional acceleration of the vehicle 100 is caused, which is perceived by the user of the vehicle 100 as a driving experience when the second electric machine 102 is switched on.

Alternatively or additionally, as a staging measure, a reduction in the torque produced by the first electric machine 101 on the first axle 111 can be effected prior to the coupling of the second electric machine 102, as shown by way of example in Fig. 2b. The first electric machine 101 produces a target torque 221, for example, prior to the coupling process (e.g. at the detection time 201). In response to the detection of the coupling of the second electric machine 102 to be effected, the torque 220 produced by the first electric machine 101 can be reduced to a reduced torque 222 (which is smaller than the target torque 221 (e.g. by 5% or more or by 10% or more) from the detection time 201 onwards.

By reducing the torque 220 produced by the first electric machine 101, an additional torque reserve 223 can be generated. At the coupling time 202, the torque 220 produced by the first electric machine 101 can be raised again to the target torque 221 in order to make the additional torque reserve 223 perceptible to the user of the vehicle 100 (as a driving experience). This is shown by way of example by the temporal progression 225 of the torque 220 in Fig. 2b.

Thus, within the framework of the coupling of the second electric machine 102, one or more staging measures can be effected in order to Comfort for the user of the vehicle 100. The one or more staging measures can be implemented depending on the current driving speed of the vehicle 100 (at the detection time 201). The extent of the one or more staging measures can be reduced as the driving speed increases. If necessary, the one or more staging measures can only be implemented if the driving speed of the vehicle 100 is less than a speed threshold. On the other hand, a smooth coupling of the second electric machine 102 can be implemented if the driving speed of the vehicle 100 is greater than the second speed threshold.

As already explained at the beginning, electric vehicles 100 typically do not have a coupling between the one or more electric motors 101, 102 and one or more wheels of the vehicle 100, but are directly coupled. In all-wheel drive vehicles 100, one or more electric motors 101, 102 can be installed on each axle 111, 112 and directly coupled to the respective driven axle 111, 112. This direct coupling allows a very dynamic design of the electric drive in relation to the torque build-up according to the driver's request (e.g. pedal request). For constant travel of the vehicle 100 (at a constant driving speed), one driven axle 111 in the vehicle 100 is typically sufficient, which is why the other axle 112 can be deactivated or even uncoupled due to efficiency advantages. This coupling and decoupling can take place in the background, preferably in a way that is not noticeable to the user and/or smoothed out in relation to the torque build-up or reduction.

The coupling or decoupling of an electric machine 102 via a decoupling unit 103 typically acts like a dead time during torque build-up. The result is a delayed and/or smoothed torque build-up in dynamic Accelerator pedal requirements compared to a system without a decoupling unit 103 or with a permanently closed decoupling unit 103.

In this document it is proposed (at least at driving speeds that are lower than a speed threshold value; and/or dependent on the driving speed and/or dependent on one or more external boundary conditions) not to conceal the dead time of the decoupling unit 103 by means of a delayed and/or smoothed torque build-up, but to deliberately stage the connection (i.e. closing) of the decoupling unit 103 by means of a specific torque build-up. The connection can thus be used as an emotionalizing means.

For this purpose, coupling and/or direct switching can be effected via user interaction on a control element 104 (e.g. on a shift paddle and/or on a kick-down pedal). The user can thus actuate the control element 104 to effect the coupling of the second electric machine 102.

Another example of a staging measure is to over-rev the uncoupled (second) electric motor 102 before coupling to use the moment of inertia as additional punch potential. When coupled, this generates an additional acceleration peak and/or an additional acoustic peak, which can be used for staging.

As a further exemplary staging measure, a centrifugal force unit (eg with a flywheel, such as a flywheel) can be driven in advance of the switching on of the second electric machine 102. The centrifugal force unit can be driven by the second electric machine 102, for example. The centrifugal force unit can then also be coupled when the second electric machine 102 is switched on in order to bring about additional acceleration, which can be used for staging. As a further exemplary staging measure, before the second (possibly rear) electric machine 102 is connected via the decoupling unit 103, the first (e.g. front) electric machine 102 can only provide a reduced torque 222 so that the torque potential 223 of the entire drive train felt by the user increases during coupling.

Fig. 3 shows a flow chart of a (possibly computer-implemented) method 300 for coupling a second electric machine 102 by means of a decoupling unit 103 to a wheel of a vehicle 100, while the vehicle 100 is already being driven by a first electric machine 101. The first electric machine 101 can be configured to drive one or more wheels on a first axle 111 of the vehicle 100. The second electric machine 102 can be configured to drive one or more wheels on a second axle 112 of the vehicle 100 when, in particular as soon as, the second electric machine 102 is coupled to the second axle 112, and thus to the one or more wheels on the second axle 112.

The method 300 includes determining 301 that the second electric machine 102 should be coupled to the wheel of the vehicle 100 (in order to drive the wheel). This can be detected, for example, based on the actuation of a control element 104 of the vehicle 100. The determining 301 can take place at a detection time 201.

Furthermore, the method 300 comprises, in response to the determining 301, the effecting 302 of at least one staging measure by which the coupling of the second electric machine 102 becomes perceptible for a user of the vehicle 100. In other words, an (additional) staging measure can be effected as part of the coupling process, which is perceptible for the user of the vehicle 100 (eg acoustically and/or as additional acceleration). By coupling the second electric machine 102 to the wheel, a basic jolt and/or a basic acceleration and/or a basic noise and/or a basic display can be caused (for example as a result of closing the decoupling unit 103). The at least one staging measure can be designed in such a way that the measure causes a jolt that goes beyond the basic jolt and/or an acceleration that goes beyond the basic acceleration and/or a noise that goes beyond the basic noise and/or a display that goes beyond the basic display. In this way, the coupling of the second electric machine 102 can be perceived by the user as a driving experience (and not as a disturbing effect).

The measures described in this document can increase the comfort of a user of a vehicle 100 when coupling an electric machine 102. Furthermore, a particularly efficient coupling or uncoupling of an electric machine 102 can be made possible (e.g. by using a claw coupling).

The present invention is not limited to the embodiments shown. In particular, it should be noted that the description and the figures are only intended to illustrate the principle of the proposed methods, devices and systems by way of example.

Claims

Expectations

1) Device (110) for coupling a second electric machine (102) by means of a decoupling unit (103) to a wheel of a vehicle (100), while the vehicle (100) is already driven by a first electric machine (101); wherein the device (110) is designed

- to determine that the second electric machine (102) is to be coupled to the wheel of the vehicle (100); and

- in response to the determination, to effect at least one staging measure by which the coupling of the second electric machine (102) becomes perceptible to a user of the vehicle (100).

2) Device (110) according to claim 1, wherein the device (110) is configured, as part of a staging measure,

- to cause a torque (220) produced by the first electric machine (101) to be reduced, in particular by a torque reserve (223), before a coupling time (202); and

- to cause the torque (220) produced by the first electric machine (101) to be increased again, in particular by the torque reserve (223), at the coupling time (202) at which the coupling of the second electric machine (102) takes place.

3) Device (110) according to claim 2, wherein the device (110) is configured to cause the torque (220) produced by the first electric machine (101) to be increased suddenly at the coupling time (202), in particular by the torque reserve (223).

4) Device (110) according to one of claims 2 to 3, wherein the device (110) is arranged to determine the torque (220) caused by the first electric machine (101) starting with a detection time (201) at which it is determined that the second electric machine (102) is to be coupled to the wheel of the vehicle (100), up to the coupling time (202), in particular continuously.

5) Device (110) according to one of the preceding claims, wherein the device (110) is set up, as part of a staging measure,

- to cause that before a coupling time (202) a speed

(210) of the second electric machine (102) is increased to an excessive speed (212) which is greater than a target speed (211) of the second electric machine (102); wherein the target speed

(211) depends on a current speed of the wheel of the vehicle (100); and

- to cause, at the coupling time (202), the second electric machine (102) to be coupled to the wheel of the vehicle (100) via the decoupling unit (103), so that due to the excessive speed (212) of the second electric machine (102) and due to an inertia of a shaft of the second electric machine (102), an effect perceptible to the user is generated, in particular with respect to additional vehicle acceleration and/or with respect to a noise and/or with respect to a graphic representation.

6) Device (110) according to claim 5, wherein the device (110) is configured to increase the rotational speed (210) of the second electric machine (102) to the excessive rotational speed (212) starting from a detection time (201) at which it is determined that the second electric machine (102) is to be coupled to the wheel of the vehicle (100) until the coupling time (202). ) Device (110) according to one of the preceding claims, wherein the device (110) is arranged

- to determine that the second electric machine (102) is to be coupled to the wheel of the vehicle (100) for recuperation;

- as part of a staging measure, to ensure that, before a coupling time (202), a rotational speed (210) of the second electric machine (102) is set to a reduced rotational speed which is lower than a target rotational speed (211) of the second electric machine (102); wherein the target rotational speed (211) depends on a current rotational speed of the wheel of the vehicle (100); and

- to cause the second electric machine (102) to be coupled to the wheel of the vehicle (100) via the decoupling unit (103) at the coupling time (202), so that due to the reduced speed of the second electric machine (102) and due to an inertia of a shaft of the second electric machine (102), an effect perceptible to the user is generated, in particular with regard to an additional vehicle deceleration and/or with regard to a noise and/or with regard to a graphic representation. ) Device (110) according to one of the preceding claims, wherein the device (110) is set up,

- to determine at a detection time (201) that the second electric machine (102) is to be coupled to the wheel of the vehicle (100);

- at a subsequent coupling time (202), to cause the second electric machine (102) to be coupled to the wheel of the vehicle (100) via the decoupling unit (103), in particular by closing the decoupling unit (103); and

- to prepare the staging measure between the detection time (201) and the coupling time (202) in such a way that at the coupling time (202) the coupling of the second electric machine (102) is perceptible to the user of the vehicle (100), in particular by an additional vehicle acceleration and/or by a noise and/or by a graphic representation. ) Device (110) according to one of the preceding claims, wherein

- the vehicle (100) comprises a control element (104), in particular a shift paddle and/or a kick-down pedal; and

- the device (110) is arranged

- to detect an actuation of the control element (104); and

- to determine based on the detected actuation that the second electric machine (102) should be coupled to the wheel of the vehicle (100). 0) Device (110) according to one of the preceding claims, wherein the device (110) is arranged,

- to determine a driving speed and/or an acceleration of the vehicle (100); and

- to effect the one or more staging measures as a function of the driving speed and/or the acceleration of the vehicle (100), in particular to adapt an extent of the one or more staging measures, such as the level of a torque reserve (223) of the first electric machine (101) effected as part of a staging measure and/or the level of an excessive speed (212) of the second electric machine (102) effected as part of a staging measure, as a function of the driving speed and/or the acceleration. ) Device (110) according to claim 10, wherein the device (110) is arranged

- to trigger one or more staging measures when the driving speed is less than a speed threshold and/or when the acceleration is less than an acceleration threshold; and/or

- not to trigger one or more staging measures if the driving speed is greater than the speed threshold and/or if the acceleration is greater than an acceleration threshold; and/or

- to reduce the extent of the one or more measures, in particular the level of the torque reserve (223) and/or the level of the excessive speed (212), with increasing driving speed and/or with increasing acceleration. ) Device (110) according to one of the preceding claims, wherein

- the first electric machine (101) is designed to drive a first axle (111) of the vehicle (100);

- the second electric machine (102) is designed to drive a second axle (112) of the vehicle (100); and

- the first axle (111) is a front axle and the second axle (112) is a rear axle, or the first axle (111) is a rear axle and the second axle (112) is a front axle. ) Device (110) according to one of the preceding claims, wherein the device (110) is set up, as part of a staging measure, to cause a centrifugal force unit, in particular by the second electric machine (102), to be driven before a coupling time (202); and - to cause the second electric machine (102) and the driven centrifugal force unit to be coupled to the wheel of the vehicle (100) via the decoupling unit (103) at the coupling time (202), so that the driven centrifugal force unit produces an effect that is perceptible to the user, in particular with regard to additional vehicle acceleration and/or with regard to a noise and/or with regard to a graphic representation. ) Method (300) for coupling a second electric machine (102) by means of a decoupling unit (103) to a wheel of a vehicle (100) while the vehicle (100) is already being driven by a first electric machine (101); wherein the method (300) comprises,

- determining (301) that the second electric machine (102) is to be coupled to the wheel of the vehicle (100); and

- in response to the determination (301), effecting (302) at least one staging measure by which the coupling of the second electric machine (102) becomes perceptible to a user of the vehicle (100).