WO2024022829A1

WO2024022829A1 - Method for controlling components of a secondary drive axle, which can be driven if necessary, of a motor vehicle driven using multiple axles

Info

Publication number: WO2024022829A1
Application number: PCT/EP2023/069377
Authority: WO
Inventors: Philipp Wagner; Philipp Beierer; Christopher Stroh; Klaus Negele
Original assignee: Man Truck & Bus Se
Priority date: 2022-07-26
Filing date: 2023-07-12
Publication date: 2024-02-01
Also published as: DE102022118650A1

Abstract

The invention relates to a method for controlling components of a secondary drive axle, which can be driven if necessary, of a motor vehicle driven using multiple axles. The motor vehicle (1) comprises a driven primary drive axle (2) and a secondary drive axle (10) which can be driven if necessary. The secondary drive axle is driven by means of at least one electric machine (12) as the drive source, wherein an operative connection between the at least one electric machine (12) and the wheels (11) of the secondary drive axle (11) can be selectively established or interrupted by means of a coupling device (13). The method has the step of actuating the at least one electric machine (12) and the coupling device (13) in order to produce at least one operating mode (100; 200; 300), in which the at least one electric machine (12) is operated at a rotational speed which is greater than null and no drive torque or substantially no drive torque or drag torque is generated on the secondary drive axle (10). The motor vehicle additionally comprises a controller for actuating the at least one electric machine (12) and the coupling device (13), said controller (5) being designed to carry out the method.

Description

Method for controlling components of a secondary drive axle, which can be driven as required, of a multi-axle driven motor vehicle

Description

The invention relates to a method for controlling components of a secondary drive axle of a multi-axle driven motor vehicle that can be driven as required. The invention further relates to such a multi-axle driven motor vehicle.

Electrically driven secondary drive axles are known from practice, particularly in the commercial vehicle sector. These are electrically driven axles (auxiliary axles) that only serve as traction support for a certain portion of a vehicle's mileage in order to support the primary drive axle when necessary. In contrast, the primary drive axle is always active when drive power needs to be provided.

Although the secondary drive axle only serves as traction support for a certain portion of the commercial vehicle's mileage, the high mileage in the commercial vehicle sector still places enormous demands on the service life of the engines and rolling bearings. This applies in particular to electrical machines for generating the drive power for electrically driven axles, since these usually have a higher speed level than internal combustion engines. Larger reduction ratios are therefore required to achieve the high torque required to drive commercial vehicles. In connection with the high mileage of commercial vehicles, the requirements for the service life of the electric machine and/or bearings become high and expensive, even if the electric machine is only used as traction support for a certain proportion of the commercial vehicle's mileage.

The invention is therefore based on the object of creating an improved technology for an electrically driven secondary drive axle if necessary.

These tasks are solved by methods and a motor vehicle with the features of the independent claims. Advantageous further developments are specified in the dependent claims and the description.

A first general aspect of the present disclosure relates to a method for controlling components of a secondary drive axle that can be driven as required multi-axle driven motor vehicle. Here, the motor vehicle comprises a driven first axle, preferably a permanently driven first axle, which is hereinafter referred to as the primary drive axle, and a second axle that can be driven if necessary, which is hereinafter referred to as the secondary drive axle.

The secondary drive axle represents a purely electrically driven additional axle, the drive power of which can be optionally switched on to provide additional drive power, which is provided in addition to the drive power of the primary drive axle. As already stated above, this is an electrically driven axle (auxiliary axle), which only serves as traction support for a certain portion of the vehicle's driving performance in order to support the primary drive axle if necessary. In contrast, the primary drive axle is always active when drive power needs to be provided.

The secondary drive axle is driven by at least one electric machine as a drive source, wherein an operative connection between the at least one electric machine and the wheels of the secondary drive axle can be selectively established or interrupted by means of a coupling device. By means of the coupling device, drive components of the electrically driven additional axle, in particular the at least one electric machine, can be decoupled from the co-rotating wheels when not in use in order to minimize wear and friction losses. It is advantageous to use simpler components without restricting the function. If, for example, one assumes that the secondary drive axle has a share of 20% of the total service life as active or standby, one can use significantly simpler components in terms of individual operating time with the same performance compared to a continuously running system.

The method includes controlling the at least one electric machine and the clutch device to implement at least one operating mode in which the at least one electric machine is operated at a speed greater than zero and generates no or substantially no drive torque or drag torque on the secondary drive axle.

Through this at least one operating mode, in phases in which the secondary drive axle is not intended to provide any drive power, an operating behavior of the drive components of the secondary drive axle is generated, which is rapid Enables the additional drive provided by the secondary drive axle to be switched on as needed and at the same time keeps wear and friction losses as low as possible.

According to a preferred embodiment, the at least one operating mode comprises a first operating mode in which the clutch device is opened (to interrupt the operative connection between the at least one electric machine and the wheels of the secondary drive axle) and in that the at least one electric machine is operated at a speed that is small and/or which lies in a range between 0 rpm and 100 rpm.

This first operating mode effectively avoids damage to e.g. B. Bearings that act on components of the secondary drive axle due to swelling, high-frequency static loads are avoided. At the same time, the power requirement for this operating mode is negligible compared to the vehicle's total energy consumption.

A “small” speed is understood to mean a speed > 0 rpm, which is sufficiently small to minimize drag or idling losses of the secondary drive axle if there is no operative connection between the at least one electric machine and the wheels of the secondary drive axle when the clutch device is open . Due to the speed > 0 rpm with the clutch device open at the same time, component damage due to static load can be avoided, which would otherwise occur at a speed = zero, e.g. B. stationary bearings may cause disproportionate damage (static point load on rolling elements). The low speed prevents component damage due to static loads. In this first operating mode, the at least one electric machine is deliberately kept in motion at a low speed, even though it is not intended to generate any drive power, in order to avoid possible bearing loads and damage that would otherwise occur when the electric machine is completely at rest.

Preferably, the first operating mode is used when the motor vehicle is moving and/or at a driving speed that is greater than a predetermined minimum speed. The predetermined minimum speed can, for example, have a value that is in a range between 5 km/h and 50 km/h.

In a further embodiment, the at least one operating mode may include a second operating mode in which the clutch device is opened (for interruption the operative connection between the at least one electric machine and the wheels of the secondary drive axle) and in that the at least one electric machine is operated at a speed that is adapted to a wheel speed of the secondary drive axle. In this second operating mode, due to the open clutch device, as in the first operating mode, there is no operative connection between the at least one electric machine and the wheels of the secondary drive axle. A speed of the electric machine that is adapted to the wheel speed is understood to mean a speed which - taking into account any existing step-up and/or step-down steps - enables the clutch device to close as smoothly as possible. Additionally or alternatively, a speed adapted to the wheel speed of the secondary drive axle can be understood to mean a speed that is similar to, but not necessarily the same as, the wheel speed of the secondary axle. At the “same” speed, it should preferably be ensured that the positive coupling, e.g. B. the claw clutch, can engage when activated and does not block (“hill on hill”). Accordingly, an input variable should preferably also record the relative rotation angle position of both coupling halves. This can be avoided by deliberately specifying a small differential speed so that, for example, the claw engages in a sufficiently short time without generating a “too large” switching shock (angular acceleration at the moment of engagement).

However, due to the adjusted speed, the additional drive provided by the secondary drive axle can be switched on more quickly than in the first operating mode. In contrast, the power requirement for this second operating mode is higher than in the first operating mode.

In a further embodiment, the at least one operating mode may include a third operating mode in which the clutch device is closed (for establishing the operative connection between the at least one electric machine and the wheels of the secondary drive axle) and in which the at least one electric machine is operated in a load-free operating mode becomes. In the third operating mode, the secondary drive axle generates no drive or recuperation power, but can be switched on particularly quickly at any time as required. The additional drive power provided by the secondary drive axle can be switched on even faster than in the second operating mode, but wear and efficiency losses in the third operating mode must be accepted. For example, the at least one electric machine can be de-energized in the load-free operating mode or can only be energized to compensate for internal bearing losses and/or the drag torque of the at least one electric machine.

The operating modes described above (first, second and third operating modes) are therefore characterized by the fact that in phases in which the secondary drive axle is not intended to provide any drive power, an operating behavior of the drive components of the secondary drive axle is generated in which, in particular, the electric machine is not at rest, i.e . H. whose speed is greater than zero in order to enable the additional drive provided by the secondary drive axle to be switched on quickly as required and/or at the same time to keep bearing loads and wear as low as possible.

The method for controlling the secondary drive axle, which can be driven as required, can further include two further operating modes, which are known per se from the prior art.

In a further optional operating mode, the clutch device is opened and the at least one electric machine is switched off, so that it is at rest and its speed is zero. This condition is optimal from an overall efficiency perspective when there is no additional traction requirement, as unnecessary drag torque is minimized. On the other hand, compared to the first operating mode, loads arise on z. B. stationary bearings etc., which may cause disproportionate damage to them. The use of this operating mode can be more advantageous than the first operating mode when driving very slowly because the possible bearing loads are low, while the use of the first operating mode can be more advantageous at higher driving speeds that are greater than the minimum speed mentioned above.

In a further operating mode, the clutch device is closed and a torque is applied to the wheels of the secondary drive axle, which is generated by the at least one electric machine, so that it can provide additional drive power or recuperation power.

Further structurally advantageous design variants of the secondary drive axle are described below.

The coupling device preferably comprises at least one positive coupling, more preferably a claw coupling. This enables great efficiency minimal installation space. The claw clutches can be engaged either when the machine is at a standstill or when the at least one electric machine is running up without load.

In a further embodiment, the at least one electric machine comprises only one electric machine, which is preferably in drive connection and/or can be brought to an input shaft of a differential gear of the secondary drive axle. Optionally, a reduction gear can be arranged between the electric machine and the input shaft and/or the wheels of the secondary drive axle.

The clutch device can include a clutch that is arranged between the electric machine and the differential gear of the secondary drive axle. In other words, a clutch is arranged directly on or as close as possible to the electrical machine. Advantageously, the entire axle can be coupled and uncoupled with a single coupling element. Another advantage is that the integration of the coupling close to the electric machine allows the combination with existing axis concepts, e.g. B. from the portfolio of conventional all-wheel drive axles, made easier because these i.e. d. R. do not have any integrated coupling elements for coupling and uncoupling.

Alternatively or additionally, the clutch device can comprise two clutches, each of which is arranged on one of two wheel drive shafts. The wheel drive shafts are drive shafts through which the wheels of the secondary drive axle are in drive connection with the differential gear. The clutches can be arranged on a wheel-side end region of the wheel drive shafts. A clutch is therefore advantageously arranged as close as possible to the wheel or wheel part or integrated into the wheel or wheel part. The advantage of this arrangement is that drag losses are minimized when the additional drive is decoupled. Due to the arrangement of the clutch close to the wheel, it is also advantageous to know the clutch status of the switching element at all times in order to avoid unwanted effects on the longitudinal dynamics, e.g. B. to avoid one-sided propulsion due to a coupling error.

In a further embodiment, the at least one electrical machine comprises two electrical machines. According to a possible embodiment variant of this, one of the two wheel sides of the secondary drive axle is driven by one of the two electric machines and the other of the two wheel sides is driven by the other of the two electric machines. Accordingly, there is no mechanical connection between the two sides of the wheel. For example, the two electric machines can each drive a wheel drive shaft via an angular gear assigned to the respective electric machine. The angular gear can be a reducing angular gear.

According to an alternative embodiment, the two electric machines can also act in parallel to drive an axle differential (differential gear) of the secondary axle, which is in drive connection with both wheel sides of the secondary drive axle and / or can be brought.

It is further emphasized that the at least one electrical machine, in particular an output shaft of the at least one electrical machine, is orthogonal to the secondary drive axis, parallel to the secondary drive axis, e.g. B. in front of or behind the secondary drive axle, or coaxial to the secondary drive axle, e.g. B. can be arranged to the left or right of a plane of symmetry of the secondary drive axle. Optionally, a reduction gear can be arranged between the electrical machines and an input shaft and/or the wheels of the secondary drive axle.

According to a further aspect of the disclosure, the clutch device may comprise two clutches, each of which is arranged between one of the two electric machines and the secondary drive axle. Advantageously, the entire secondary drive axle can be coupled and uncoupled using two individual clutches. For example, one of the clutches can be arranged between one of the electrical machines and a reduction gear of the secondary drive axle.

Alternatively or additionally, the clutch device can comprise two clutches, each of which is arranged on one of the two wheel drive shafts. Particularly preferably, the two clutches are each arranged at a wheel-side end region of one of the two wheel drive shafts and/or arranged as close as possible to the wheel or wheel part or integrated into the wheel or wheel part. The advantage of this design variant is the minimization of drag losses when the additional drive is decoupled.

A second general aspect of the present disclosure relates to a motor vehicle comprising a permanently driven primary drive axle and a secondary drive axle that can be driven as required. The secondary drive axle is driven by at least one electric machine as a drive source, with an operative connection between the at least one electric machine and the wheels of the secondary drive axle can be either established or interrupted by means of a coupling device. The motor vehicle further comprises a control device for controlling the at least one electric machine and the clutch device, wherein the control device is designed to carry out the method as described and disclosed herein.

Preferably, the term “control device” can refer to electronics (e.g. designed as a driver circuit or with microprocessor(s) and data memory) and/or a mechanical, pneumatic and/or hydraulic control which, depending on the training, carries out control tasks and/or or can take on control tasks and/or processing tasks. Even if the term “controls” is used here, it can also appropriately include or mean “rules” or “controls with feedback” and/or “processing”.

The vehicle is preferably a purely electrically powered motor vehicle. Accordingly, the primary drive axle can also be a purely electrically driven axle. The primary drive axle and the secondary drive axle are driven by different electric machines.

The motor vehicle can be a commercial vehicle, preferably a purely electrically powered commercial vehicle. A commercial vehicle is a vehicle that is designed and designed to transport people, transport goods or tow trailers. So the vehicle can e.g. B. be a truck, a tractor-trailer and/or a bus.

To avoid repetition, features disclosed purely in accordance with the device should also be considered disclosed in accordance with the method and should be claimable and vice versa. The aforementioned aspects and features according to the invention, in particular with regard to the design of the method for controlling the secondary drive axle, therefore also apply to the motor vehicle and the control device.

The previously described preferred embodiments and features of the invention can be combined with one another in any way. Further details and advantages of the invention are described below with reference to the accompanying drawings. Show it:

Figure 1 shows a schematic top view of a secondary drive axle and a control device according to an exemplary embodiment of the present disclosure; Figure 2 shows a highly schematic representation of a control device to illustrate a method according to an exemplary embodiment of the present disclosure;

Figures 3 to 5 each show a schematic top view of a secondary drive axle and a control device according to further exemplary embodiments of the present disclosure; and

Figure 6 shows a motor vehicle according to an exemplary embodiment of the present disclosure.

The embodiments shown in the figures are at least partially the same, so that similar or identical parts are provided with the same reference numerals and for their explanation reference is also made to the description of the other embodiments or figures in order to avoid repetitions.

Figure 1 shows a schematic top view of a secondary drive axle 10 and a control device 5 of a multi-axle driven motor vehicle. The motor vehicle will be described in more detail below in connection with Figure 6.

The secondary drive axle 10 represents a purely electrically driven additional axle, the drive power of which can optionally be switched on to provide additional drive power, which is provided in addition to the drive power of a primary drive axle.

In the exemplary embodiment shown in FIG. 1, the secondary drive axle 10 is driven by two electric machines 12 as a drive source. The electric machines 12 are arranged in the longitudinal direction of the vehicle on two opposite sides of the axle body 17 of the secondary drive axle 10. The secondary drive axle 10 is designed here as a rigid axle. The electrical machines 12 are each drivingly connected to an input shaft of an angular gear 15 via a reduction gear 14. In the present case, two such angular gears 15 are integrated into the secondary drive axle, each of which is connected in terms of drive technology to one of the two wheel drive axles 16. The angular gears are preferably reducing angular gears 15. Each of the two wheel sides of the secondary drive axle is therefore only driven by one of the two electric machines 12. Accordingly, there is no mechanical active connection between the two wheel sides of the secondary drive axle 10. In the example of Figure 1, the two electrical machines 12 are arranged orthogonally to the secondary drive axle 10. It goes without saying that the electrical machines 10 can alternatively be parallel to the secondary drive axle 10, e.g. B. in front of or behind the secondary drive axle 10, or coaxial to the secondary drive axle 10, z. B. can be arranged to the left or right of a plane of symmetry of the secondary drive axle 10.

According to an alternative embodiment variant (not shown), the two electric machines can also act in parallel to drive an axle differential (differential gear) of the secondary axle, which is in drive connection with both wheel sides of the secondary drive axle and / or can be brought.

Furthermore, a coupling direction 13 is provided, by means of which an active connection between the electrical machines 12 and the wheels 3 of the secondary drive axle 10 can be either established (clutch device 13 closed) or interrupted (clutch device 13 opened). In other words, by means of the coupling device 13, drive components of the electrically driven additional axle 10, in particular the electrical machines 12 and the reduction gears 14, can be decoupled from the co-rotating wheels 3 when not in use in order to minimize wear and friction losses.

1, the coupling device 13 comprises, for example, two couplings 13b, which are arranged at a wheel-side end region of one of the two wheel drive shafts 16 and/or are arranged as close as possible to the wheel 3 or wheel part or are integrated into the wheel or wheel part. The clutch actuator system of the clutch device 13 can be implemented mechanically, pneumatically, hydraulically, electrically or as a combination thereof. The clutches 13b are preferably designed here as claw clutches. The wheels 3 are articulated to the wheel drive shafts 16 via universal joints 18.

Furthermore, a control device 5 is provided, which is connected to the clutches 13b and the electrical machines 12 in terms of signaling via control lines (shown as dashed lines). The control device 5 is designed to control the electrical machines 12 and the clutches 13b, which will be explained in more detail below in connection with FIG. Figure 2 shows a highly schematic representation of the control device 5. A method for controlling the components of the secondary drive axle 10 is also explained based on Figure 2.

The method includes several operating modes, preferably the operating modes 100 - 500, which can be selected depending on the operating situation of the motor vehicle in order to adjust the operating state of the secondary drive axle 10, in particular to adjust the operating state of the electrical machines 12 and the clutch device 13 or the clutches 13b.

These operating modes 100 - 500 are stored in the control device 5. In other words, the control device 5 is set up in terms of programming to select one of the operating modes 100 - 500 according to previously stored criteria, depending on the operating situation of the motor vehicle, and to control the components of the secondary drive axle 10 according to the selected operating mode.

A special feature of the exemplary embodiment shown is that the selectable operating modes include at least one of the three operating modes 100, 200, and 300, preferably include all three operating modes 100, 200 and 300, in which phases in which the secondary drive axle is not intended to provide any drive power Operating behavior of the drive components of the secondary drive axle is generated, in which in particular the electrical machines 12 are not at rest, i.e. H. whose speed is greater than zero in order to enable the additional drive provided by the secondary drive axle 10 to be switched on quickly as required.

Preferably, a first operating mode 100 can be selected, according to which the control device 5 controls the clutch device 13 so that it is opened (to interrupt the operative connection between the electrical machines 12 and the wheels 3 of the secondary drive axle 0) and in that the electrical machines 12 with a Speed is operated which is small and/or which is in a range between 0 rpm and 100 rpm.

It has already been stated above that with this first operating mode 100, it is deliberately set in motion at a low speed even in operating phases in which the electrical machines 12 are not intended to generate any additional drive power for the motor vehicle in order to avoid possible bearing loads and damage that would otherwise occur when electrical machines 12 are completely at rest.

For example, the control device 5 can be designed to select or implement the first operating mode 100 when the motor vehicle is traveling at a speed that is greater than a predetermined minimum speed and when the secondary drive axle 10 is not intended to provide any additional drive or recuperation power.

Preferably, a second operating mode 200 can also be selected, according to which the control device 5 controls the clutch device 13 so that it is opened (to interrupt the operative connection between the electrical machines 12 and the wheels 3 of the secondary drive axle 0) and in that the at least one electrical machine is operated at a speed that is adapted to a wheel speed of the secondary drive axle.

For example, the control device 5 can be designed to select or implement the second operating mode 200 if the first operating mode 100 was previously set and z. B. based on further operating parameters it is determined that although the secondary drive axle 10 should not (yet) provide any additional drive or recuperation power, this has become more likely.

Preferably, a third operating mode 300 can also be selected, according to which the control device 5 controls the clutch device 13 so that it is closed (to establish the operative connection between the electrical machines 12 and the wheels 3 of the secondary drive axle 0) and in that the two electrical machines 12 operated in a load-free operating mode. For example, the electrical machines 12 can be de-energized in the load-free operating mode or can only be energized to compensate for internal bearing losses and/or the drag torque of the at least one electrical machine.

For example, the control device 5 can be designed to select or implement the third operating mode 300 if the first operating mode 200 has previously been set or, alternatively, to put the secondary drive axle 10 into a standby state in which a switch can be switched on as required as possible at any time Secondary drive axle generated additional drive torque or recuperation torque is possible.

The method for controlling the secondary drive axle, which can be driven as required, can further comprise two further, known operating modes 400 and 500, which are known per se from the prior art.

In a further optional operating mode 400, the clutch device 13 is opened and the electrical machines 12 are switched off or their speed is zero. This condition is optimal from an overall efficiency perspective when there is no additional traction requirement, as unnecessary drag torque is minimized. On the other hand, compared to the first operating mode, loads arise on z. B. stationary bearings etc., which can cause disproportionate damage to them. For example, the control device 5 can be designed to set this operating mode 400 when driving very slowly because the possible bearing loads are low here.

In a further operating mode 500, the clutch device 13 is closed and a torque is applied to the wheels 3 of the secondary drive axle, which is generated by the electric machines 12, so that they can provide additional drive power or recuperation power. For example, the control device 5 can be designed to set this operating mode 500 whenever an additional drive or recuperation torque is to be provided by the secondary drive axle 10 to support the primary drive axle.

The control device 5 is in signal connection with several sensors 13c, 3a, 12a, 15a, etc. in order to obtain operating data from them. Based on the operating data, the control device 5 can check whether the actual operating state of the electrical machines 12 and the clutch device 13 corresponds to the target operating state specified by the control device 5. For example, sensors 13c on the clutch(es) 13b report the clutch status back to the control device 5. Furthermore, data from a speed sensor 15a of an angular gear 15 or differential gear 19, from speed sensors 3a on the wheel parts 3 and from speed sensors 12a on the electric machine(s) 12 can be processed in the control device 5 and, in addition to other parameters, can serve as a control or regulation variable. which controls the actuator system of the clutch actuator(s) of the clutch device 13. This means that even while driving, careful switching on and off can be achieved by targeted speed adjustment of the electric machine(s) 12 Disengagement of the clutch element(s) can be realized. Particularly when the clutches 13b are arranged close to the wheel in FIG. B. to avoid one-sided propulsion due to a coupling error.

If you optionally combine the high control quality and control speed of electrical machines with other input variables, e.g. B. a route profile through GPS, acceleration sensors, environmental perception (visual recognition, temperature), vehicle status (e.g. current power requirement or acceleration request) as well as the operating modes described above, in particular the third operating mode, traction support can be implemented automated and highly dynamic, i.e. H. can intervene without delay.

Figures 3 to 5 show further exemplary embodiments that differ from the exemplary embodiment of Figure 1 only in the number of electrical machines 12 and/or the number and arrangement of the couplings of the coupling device 13, so that reference will only be made to these special features below.

The statements regarding the control device 5 and the method or the operating modes 100 to 500 apply analogously to those described in connection with FIG. 2, whereby instead of two electric machines 12 and two clutches in FIGS becomes.

In comparison to Figure 1, the special feature of the secondary drive axle 10 of Figure 3 is that a clutch 13a is arranged directly on or as close as possible to the electrical machine 12. The entire axle can advantageously be coupled and uncoupled with two clutches 13a.

Compared to FIG. 3, the special feature of the secondary drive axle 10 of FIG. 4 is that only one electric machine 12 (instead of two) is provided. Accordingly, only one clutch 13a is provided, which is arranged directly on or as close as possible to the electrical machine 12. The entire axle can advantageously be coupled and uncoupled with a coupling 13a. Another difference is that the electric machine 12 is in drive connection with both wheel sides of the secondary drive axle and/or can be brought via an axle differential 19 integrated into the secondary drive axle 10. In comparison to FIG. 4, the special feature of the secondary drive axle 10 of FIG.

Figure 6 shows a motor vehicle 1. The motor vehicle 1 is preferably as a commercial vehicle, e.g. B. a truck or a bus. For example, the truck can have a (e.g. loading) body or can be designed as a tractor-trailer vehicle, as shown in Figure 1.

The motor vehicle 1 has at least one energy storage device 6 for electrical energy. The motor vehicle 10 is preferably driven purely electrically. The energy storage 6 can be designed as a traction battery for providing electrical energy to drive the motor vehicle. The energy storage device 6 can preferably be attached to a vehicle frame of the motor vehicle 1. The vehicle frame can be designed, for example, as a grid frame or preferably as a ladder frame.

The motor vehicle comprises a permanently driven primary drive axle 2, and the secondary drive axle 10, which can be driven as required and which is driven by at least one electric machine as a drive source. The primary drive axle 2 represents the main drive axle. The secondary drive axle 10 can be designed as z. B. is shown in Figures 1 and 3 to 5. The secondary drive axle 10 represents an electrically driven additional axle, the drive power of which can optionally be switched on to provide additional drive power.

The secondary drive axle 10 can be, for example, a front axle (as shown in Figure 6) or a leading axle or trailing axle, either rigid or also steered. From a design perspective, the secondary axis can also be a structural copy of the primary axis, supplemented by the clutch function and control to implement the at least one operating mode, as described herein. The motor vehicle 1 further comprises the control device 5 for controlling the at least one electric machine 12 and the clutch device 13, the control device being designed to carry out the method as described above.

The invention is not limited to the preferred embodiments described above. Rather, a large number of variants and modifications are possible, which also make use of the inventive idea and therefore fall within the scope of protection. In particular, the invention also claims protection for the subject matter and features of the subclaims independently of the claims referred to. In particular, the individual features of independent claim 1 are each disclosed independently of one another.

Reference symbol list

1 motor vehicle, for example commercial vehicle

2 primary drive axle

3 wheels

3a wheel speed sensor

4 energy storage devices for electrical energy

5 control device

6 Electrical energy storage device

10 secondary drive axle

11 wheels

12 Electric Machine

12a E-machine speed sensor

13 coupling device

13a claw coupling

13b claw coupling

13c clutch sensor

14 reduction gears

15 angle gears

15a Speed sensor of the angular gear or differential gear

16 wheel drive shaft

17 axle bodies

18 universal joint

19 differential gears

100 First operating mode

200 Second operating mode

300 Third operating mode

400 Fourth operating mode

500 Fifth operating mode

Claims

Patent claims

1. Method for controlling components of a secondary drive axle of a multi-axle driven motor vehicle (1), which can be driven as required, the motor vehicle (1) comprising: a) a permanently driven primary drive axle (2), and b) a secondary drive axle (10) which can be driven as required and which has at least an electric machine (12) is driven as a drive source, wherein an operative connection between the at least one electric machine (12) and the wheels (11) of the secondary drive axle (11) can be selectively established or interrupted by means of a coupling device (13), the method a control of the at least one electric machine (12) and the clutch device (13) to realize at least one operating mode (100; 200; 300) in which the at least one electric machine (12) is operated at a speed greater than zero and no or Substantially no drive torque or drag torque is generated on the secondary drive axle (10).

2. The method according to claim 1, wherein the at least one operating mode comprises a first operating mode (100) in which the clutch device (13) is opened to interrupt the operative connection between the at least one electrical machine

(12) and the wheels (13) of the secondary drive axle (10) and in that the at least one electric machine (12) is operated at a speed that is in a range between 0 rpm and 100 rpm.

3. The method according to claim 2, wherein the first operating mode (100) is used when the motor vehicle is moving and at a driving speed that is greater than a predetermined minimum speed.

4. The method according to claim 3, wherein the predetermined minimum speed has a value which is in a range between 5 km/h and 50 km/h.

5. The method according to any one of the preceding claims, wherein the at least one operating mode comprises a second operating mode (200) in which the clutch device

(13) is opened to interrupt the operative connection between the at least one electric machine (12) and the wheels (13) of the secondary drive axle (10) and thereby the at least one electric machine (12) is operated at a speed that is adapted to a wheel speed of the secondary drive axle (10).

6. The method according to any one of the preceding claims, wherein the at least one operating mode comprises a third operating mode (300), in which the clutch device (13) is closed to establish the operative connection between the at least one electric machine (12) and the wheels (13). the secondary drive axle (10) and in that the at least one electrical machine (12) is operated in a load-free operating mode.

7. The method according to claim 6, wherein the at least one electrical machine (12) in the load-free operating mode a) is not energized, or b) is energized only to compensate for internal bearing losses and / or the drag torque of the at least one electrical machine (12).

8. The method according to any one of the preceding claims, wherein the coupling device (13) comprises at least one positive coupling, preferably a claw coupling (13).

9. The method according to any one of the preceding claims, wherein the at least one electrical machine (12) comprises only one electrical machine (12) which is in drive connection and/or can be brought to an input shaft of a differential gear (19) of the secondary drive axle (10), wherein a reduction gear (14) is preferably arranged between the electrical machine (12) and the input shaft.

10. The method according to claim 9, wherein the clutch device (13) comprises a clutch (13a) which is arranged between the electric machine and the differential gear of the secondary drive axle.

11. The method according to claim 9 or 10, wherein the wheels (11) of the secondary drive axle (10) are in drive connection with the differential gear (19) via one of two wheel drive shafts (16) and the coupling device (13) comprises two clutches (13b). , which are arranged on one of the two wheel drive shafts (16), preferably on a wheel-side end region of one of the two wheel drive shafts (16). 12. The method according to any one of claims 1 to 8, wherein the at least one electrical machine (12) comprises two electrical machines which are arranged on opposite sides of the secondary drive axle (10).

13. The method according to claim 12, wherein the clutch device (13) comprises two clutches (13a), each of which is arranged between one of the two electrical machines (12) and a reduction gear (15) of the secondary drive axle (10).

14. The method according to claim 12, wherein the wheels (11) of the secondary drive axle (10) are in drive connection with one of two reduction gears (15) via one of two wheel drive shafts (16) and the coupling device (13) comprises two clutches (13b). , which are each arranged on one of the two wheel drive shafts (16), are preferably arranged on a wheel-side end region of one of the two wheel drive shafts (16).

15. Motor vehicle (1), preferably purely electrically driven commercial vehicle, comprising a) a permanently driven primary drive axle (2), and b) a secondary drive axle (10) which can be driven as required and which is driven by at least one electric machine (12) as a drive source, wherein an operative connection between the at least one electric machine (12) and the wheels (11) of the secondary drive axle (10) can be selectively established or interrupted by means of a coupling device (13), and c) a control device (5) for controlling the at least one electric machine (12) and the coupling device (13), wherein the control device (5) is designed to carry out the method according to one of claims 1 to 14.