Brake system and electric axle drive train of motor vehicle

Abstract

The invention relates to a brake system (1) of a motor vehicle (3) that can be electrically driven by means of an electric machine (2), the brake system (1) having a plate brake (4) with a plurality of inner friction plates (5) and a plurality of outer friction plates (6), which can be brought into frictional engagement by means of a brake actuator (7), and the electric machine (2) having a rotor (8), which can be brought into frictional engagement by means of the brake actuator (7). The disc brake (4) is accommodated in a brake housing (9), and the inner friction plate (5) or the outer friction plate (6) is connected to the rotor (8) of the electric machine (2) in a torque-transmitting manner, and wherein the inner friction plate (5) and the outer friction plate (6) are connected to the rotor (8) of the electric machine (2) in a torque-transmitting manner. A wear sensor (11) is provided on at least one of the inner friction plate (5) or the outer friction plate (6), by means of which wear of the friction lining (12) on one of the inner friction plate (5) or the outer friction plate (6) can be detected.

Description

Technical Field

[0001] The invention relates to a braking system for a motor vehicle that can be electrically driven by means of an electric motor, wherein the braking system has a multi-disk brake with a plurality of inner friction plates and a plurality of outer friction plates that can be brought into frictional engagement by means of a brake actuator, and the electric motor has a rotor that is coupled to at least one wheel of the motor vehicle in a torque-transmitting manner. The invention also relates to an electric axle drivetrain for a motor vehicle. Background Art

[0002] In motor vehicles, electric motors are increasingly being used for the drive in order to provide an alternative to internal combustion engines that consume fossil fuels. Considerable efforts have been made to improve the everyday usability of electric drives and to provide the user with the driving comfort that is customary. A detailed description of electric drives is given in the article by Erik Schneider, Frank Fickl, Bernd Cebulski and Jens Liebold in the journal ATZ, 113th year, May 2011, pages 360 to 365, entitled “Hochintegrativ und Flexibel Elektrische Antriebseinheit für E-Fahrzeuge”. In the article, a drive unit for an axle of a vehicle is described, which drive unit comprises an electric motor arranged coaxially with a bevel gear differential.

[0003] Such motor vehicles with hybrid or electrified drivetrains can not only be accelerated but also braked by means of the electric machine. During braking, the electric machine is operated as a generator and the recovered energy is used, for example, to charge a battery. However, for safety reasons, a further mechanical brake system is still required. In the case of drives close to the wheels, such as wheel hub motors or electric axles, this results in difficult installation space conditions.

[0004] In particular, in the case of vehicles with electric wheel hub drives, so-called electric wheel drives, brakes with friction disks are usually used to brake the vehicle. However, brakes designed as disk brakes with floating calipers, disk brakes with fixed calipers, drum brakes and multi-disk brakes are also known.

[0005] For example, DE 10 2019 120 409 A1 discloses a brake device for a wheel hub drive, wherein a brake pair fixed relative to the circumferential direction has a cooling channel. The axially movable brake pair is actuated via a brake cylinder. The brake pair movable in the circumferential direction is configured as a friction lining carrier.

[0006] There is also an increasing demand to reduce or completely avoid the emission of brake wear products which usually occur as fine dust. Summary of the invention

[0007] It is therefore an object of the present invention to provide an improved brake system having a high braking torque, a high operational safety and low brake dust emissions.

[0008] The object is achieved by a braking system for a motor vehicle that can be electrically driven by an electric motor, wherein the braking system has a disk brake with multiple inner friction plates and multiple outer friction plates, the multiple inner friction plates and multiple outer friction plates can be placed in friction fit by means of a brake actuator, and the electric motor has a rotor, which is coupled to at least one wheel of the motor vehicle in a torque-transmitting manner, wherein the disk brake is accommodated in a brake housing and the inner friction plates or the outer friction plates are connected to the rotor of the electric motor in a torque-transmitting manner, and a wear sensor is arranged on at least one of the inner friction plates or the outer friction plates, with the aid of which the wear of the friction lining at one of the inner friction plates or the outer friction plates can be detected.

[0009] This achieves the advantage that the brake wear from the disk brake can be retained in the brake housing, which directly contributes to reducing the environmental burden. The brake system according to the invention also has the advantage that the unsprung masses of the wheels can be reduced. It is also possible to increase the steering angle of the corresponding wheel by omitting the brake provided at the wheel.

[0010] In addition, the wear sensor does not need to open the brake housing to check the wear limit of the friction lining, which also reduces the risk of accidental brake dust escape. In addition, the user can be informed early that the brake lining needs to be replaced before the braking force is lost.

[0011] The brake system according to the invention has the function of braking the wheel to be braked of a motor vehicle by means of frictional engagement. The disk brake can be implemented in particular based on the functional principle of a dry or wet disk brake. In this case, the disk brake is arranged in the powertrain of the motor vehicle at a distance from the wheel. Preferably, the disk brake is coupled to the rotor of the electric machine.

[0012] The function of a multi-disk brake is to establish a releasable, friction-locking connection between a brake shaft and a mounting structure for supporting a braking torque, which is usually provided in a rotationally fixed manner. For this purpose, the inner and outer friction disks of a friction disk set, which are arranged alternately with one another, can be brought into force-locking or friction-locking contact via their respective friction linings by means of a joining process, by means of axial displacement and pressing, so that the inner friction disks can rotate relative to the outer friction disks with friction about the common axis of rotation of the corresponding friction disk set or are arranged in a rotationally fixed manner when they are completely friction-locked with one another. If, on the other hand, the inner and outer friction disks are axially separated from one another by means of a disconnection process, there is no longer a force-locking contact between the inner and outer friction disks, so that they can rotate freely relative to one another and therefore no torque or braking torque is transmitted between the inner and outer friction disks.

[0013] A disk brake is usually composed of at least two inner friction disks and / or two outer friction disks. The inner friction disks are preferably arranged in a rotationally fixed manner on the inner friction disk carrier and the outer friction disks are preferably arranged in a rotationally fixed manner on the outer friction disk carrier. The inner friction disk carrier is particularly preferably connected to the brake shaft and the outer friction disk carrier is particularly connected to a rotationally fixed attachment structure, or vice versa.

[0014] The inner friction plate and the outer friction plate form a friction plate pack of the multi-plate brake. In the friction plate pack, a plurality of inner friction plates and outer friction plates are preferably arranged alternately with each other in the axial direction. The torque or braking torque that can be transmitted between the inner friction plates and the outer friction plates by the multi-plate brake can be set by the number and design of the inner friction plates and the outer friction plates.

[0015] The inner friction plate has the function of transmitting the torque, in particular force-fitting or friction-fitting, from the outer friction plate to the inner friction plate carrier. The inner friction plate can be designed in particular as a circular ring-shaped disk. The inner friction plate can be connected to the inner friction plate carrier of the multi-plate brake in a rotationally fixed manner. It can also be provided that the inner friction plate can be moved in the axial direction relative to the inner friction plate carrier, for example via a corresponding toothing, in order to establish a friction fit with the outer friction plate.

[0016] The outer friction plate has the function of transmitting the torque, in particular force fit or friction fit, from the inner friction plate to the outer friction plate carrier. The outer friction plate can be designed in particular as a circular ring-shaped disk. The outer friction plate can be connected to the outer friction plate carrier of the multi-plate clutch in a rotationally fixed manner. It can also be provided that the outer friction plate can be moved relative to the outer friction plate carrier in the axial direction, for example via a corresponding toothing, in order to establish a friction fit with the inner friction plate. The outer friction plate carrier can be designed, for example, as an outer multi-plate clutch housing.

[0017] The friction plate group can be accommodated in one or more friction plate carriers and can in particular also be guided in a linearly movable manner. For this purpose, the inner friction plate can be accommodated in the inner friction plate carrier and the outer friction plate can be accommodated in the outer friction plate carrier. In order to form a linearly movable offset of the inner friction plate relative to the outer friction plate (or vice versa), the inner friction plate can be connected to the inner friction plate carrier via an inner splice toothing in a torque-transmitting manner and / or the outer friction plate can be connected to the outer friction plate carrier via an outer splice toothing in a torque-transmitting manner.

[0018] The multi-disk brake can preferably include a spring element. The spring element has the task of moving the inner and outer friction plates relative to each other into a predefined position in a manner that causes a spring force. Typically, the predefined position corresponds to a "normally open" or "normally closed" operating state of the multi-disk brake, which means that when the brake actuator is not actuated, the inner and outer friction plates are pressed or released relative to each other by the spring element.

[0019] Furthermore, the multi-disk brake can also have a switching piston. The switching piston has the function of converting the engagement or disengagement process predetermined by the brake actuator into an axial displacement of the inner and / or outer friction disks in order to establish a friction fit during braking or to release the friction fit when the multi-disk brake is released.

[0020] The disc brake is preferably arranged in a brake housing. The brake housing surrounds the disc brake. In addition, the brake housing can also accommodate one or more brake actuators. In addition, the brake housing can also be a component of a cooling system and be configured so that a cooling fluid can be supplied to the brake system via the brake housing and / or heat can be led outwardly via the housing surface. In addition, the brake housing protects the complementary brake from external mechanical and / or chemical influences. The brake housing can be formed in particular by a metal material. In an advantageous manner, the brake housing can be formed by a metal casting material such as gray cast iron or cast steel. In principle, it is also conceivable that the brake housing is completely or partially composed of plastic. It is also feasible that the brake housing is implemented in one piece or in multiple pieces. The brake housing can also be completely or partially configured as a part of the motor housing of the motor or the transmission housing of the transmission coupled to the motor. Preferably, the brake housing and the motor housing or the transmission housing form a structural unit. For this purpose, the brake housing can be screwed, for example, with the motor housing or the transmission housing. Preferably, the brake housing is implemented so that the wear generated during braking cannot leak from the brake housing. Undesirable environmental burdens due to brake wear can thus be avoided. Furthermore, the braking noise relative to the environment can also be reduced by such an encapsulation of the brake system.Another advantageous aspect of the encapsulation is that the braking performance of the brake system is independent of the weather conditions outside the motor vehicle.

[0021] The brake actuator has in particular the function of activating the actuator, i.e. placing it in a friction-locking operating state and in a friction-released operating state. The brake actuator can be actuated for this purpose in particular pneumatically, hydraulically, by an electric motor, mechanically, electromagnetically or in any combination thereof. The brake actuator is preferably configured as an electromechanical brake actuator.

[0022] The brake system according to the invention is preferably provided for a motor vehicle that can be electrically driven by means of an electric motor. The motor in the sense of the present application is used to convert electrical energy into mechanical energy and / or vice versa, and generally comprises a fixed part called a stator, a stator or an anchor and a part called a rotor or a rotating part and arranged movably relative to the fixed part. In the context of the present invention, the motor can be configured in particular as a rotary machine. In such electric rotary machines, a distinction is made in particular between radial flux machines and axial flux machines. Here, the radial flux machine is characterized in that the magnetic field lines extend in the radial direction in the air gap formed between the rotor and the stator, while in the case of the axial flux machine, the magnetic field lines extend in the axial direction in the air gap formed between the rotor and the stator. The motor is designed in the context of the present application in particular for use in the powertrain of a hybrid or fully electric motor vehicle. In particular, the size of the motor is determined so that a vehicle speed of more than 50 km / h, preferably more than 80 km / h and in particular more than 100 km / h can be achieved. Particularly preferably, the motor has a power greater than 30 kW, preferably greater than 50 kW and in particular greater than 70 kW. It is also preferred that the motor provides a rotational speed greater than 5000 rpm, particularly preferably greater than 10000 rpm, and most particularly preferably greater than 12500 rpm.

[0023] The electric motor can have a housing, which is also referred to as a motor housing. The motor housing encloses the electric motor. In addition, the motor housing can also accommodate control and power electronics, and preferably can also accommodate at least a part of the brake system. In addition, the motor housing can also be a component of a cooling system for the electric motor and be configured so that a cooling fluid can be supplied to the electric motor via the motor housing and / or heat can be led outwardly via the motor housing surface. In addition, the motor housing protects the electric motor and, if necessary, the electronic devices present from external mechanical and / or chemical influences. The motor housing of the electric motor can be formed in particular from a metal material. In an advantageous manner, the motor housing can be formed from a metal casting material, such as gray cast iron or cast steel. In principle, it is also conceivable that the motor housing is completely or partially composed of plastic. It is also feasible that the motor housing of the electric motor is implemented in one piece or in multiple pieces.

[0024] The rotor is the rotating (rotating) part of the electric machine. The rotor comprises in particular a rotor shaft and one or more rotor bodies formed by a rotor lamination stack and arranged in a rotationally fixed manner on the rotor shaft. The rotor shaft can be hollow, which on the one hand results in weight savings and on the other hand allows lubricants or coolants to be supplied to the rotor body. The rotor shaft can be coupled in particular to a brake shaft of a complementary brake.

[0025] The electric machine and / or the multi-disk brake can preferably be coupled to a transmission which is designed in particular to generate a drive torque for the motor vehicle. The drive torque is particularly preferably a main drive torque, so that the motor vehicle is driven solely by the drive torque.

[0026] In particular, it can be provided that the electric motor and / or the disk brake and the transmission are arranged in a common powertrain housing. Alternatively, it is of course also possible that the electric motor has a motor housing and the transmission has a transmission housing, wherein a structural unit can then be produced via the fixing of the transmission relative to the electric motor. The structural unit is sometimes also referred to as an axle. The powertrain housing is preferably made of a metal material, particularly preferably of aluminum, gray cast iron or cast steel, in particular by means of a forming method such as casting or die casting. In principle, however, it is also possible to form the powertrain housing from plastic. The powertrain housing can particularly preferably have a pot-shaped basic shape, so that the electric motor and the transmission can be inserted into the powertrain housing via the open end side of the powertrain housing.

[0027] Preferably, the electric motor has a motor housing and / or the transmission has a transmission housing, wherein a structural unit can then be formed via the fixing of the transmission relative to the electric motor. The transmission housing is a housing for accommodating the transmission. The housing has the following tasks, respectively guiding the existing shaft via bearings and providing the wheel (possibly a cam disk) with the required degrees of freedom under all loads, which degrees of freedom allow, without hindering its rotation and possible trajectory movement, as well as absorbing bearing forces and supporting moments. The transmission housing can be single-shell or multi-shell, that is to say, not separated or separated. In particular, the transmission housing should also be able to not only attenuate noise and vibrations but also to reliably accommodate hydraulic fluids. The transmission housing is preferably made of a metal material, particularly preferably of aluminum, gray cast iron or cast steel, in particular by means of a forming method such as casting or die casting.

[0028] Furthermore, the transmission can preferably be configured as a planetary transmission or include a planetary transmission. The planetary transmission can preferably have: a sun gear and a plurality of planetary gears meshing with the sun gear and rotatably supported in a planetary gear carrier, the planetary gears rotating around the sun gear; and a ring gear arranged coaxially with the sun gear, in which the planetary gears roll.

[0029] The transmission can also have a differential transmission. A differential transmission is a planetary transmission with a drive element and two driven elements. The differential transmission usually has the function of driving two wheels of a motor vehicle so that the two wheels can rotate at different speeds but with the same traction in a bend.

[0030] In order to realize different drive modes or operating modes for the motor vehicle, one or more disconnect clutches can be provided in the torque path between the electric machine and the wheels. The disconnect clutch can be arranged, for example, between the output of the electric machine and the input of the transmission, so that the electric machine can be decoupled from the transmission, thereby enabling a freewheeling operation of the motor vehicle. It is also conceivable to arrange a disconnect clutch between the output of the transmission and one or more wheels, thereby likewise enabling a freewheeling operation of the motor vehicle. Finally, it is also possible to arrange a disconnect clutch between the input of the brake system and the output of the electric machine, thereby enabling the brake system to be completely decoupled from the electric machine.

[0031] Land vehicles that move by mechanical force are considered motor vehicles in the sense of this application, which do not rely on tracks. Motor vehicles can be selected from passenger cars (PKW), trucks (LKW), scooters, light motor vehicles, motorcycles, buses (KOM) or tractors, for example.

[0032] Advantageous embodiments of the present invention are described in the dependent claims. The features listed individually in the dependent claims can be combined with each other in a technically meaningful manner and can define other embodiments of the present invention. In addition, the features described in the claims are precisely expressed and explained in detail in the description, wherein other preferred embodiments of the present invention are shown.

[0033] According to an advantageous design of the present invention, it can be proposed that the wear sensor is arranged on the axially outermost inner friction plate or outer friction plate. The advantage of the design is that the wiring distance and thus the signal transmission distance can be kept short. The arrangement is also conducive to installation-friendly replacement of the wear sensor.

[0034] According to another preferred development of the invention, provision can also be made for the wear sensor to be arranged on the outermost inner friction plate or outer friction plate on the axial end side opposite the shift piston, which likewise brings advantages in terms of installation.

[0035] Furthermore, according to an equally advantageous embodiment of the invention, it can be provided that the wear sensor is fixed in a recess which is formed in one of the inner friction plate or the outer friction plate, thereby achieving a high degree of system integration and also facilitating relatively simple installation.

[0036] According to another particularly preferred embodiment of the present invention, it can be provided that the wear sensor comprises a first signal cable and a second signal cable, which extend at least partially through the recess in the axial direction, wherein the electrically conductive ends of the signal cables terminate in a common radial plane, which has an axial spacing a from the friction surface of the corresponding inner friction plate or outer friction plate accommodating the wear sensor, so that after the friction surface is axially worn to the radial plane, the circuit between the first signal cable and the second signal cable is closed. This makes it possible to realize a wear sensor that can be manufactured cost-effectively and operates reliably.

[0037] Furthermore, the invention can also be developed in that the first signal cable and the second signal cable are fixed in the recess by means of a potting compound, which can also contribute to cost-effective production.

[0038] In a likewise preferred embodiment variant of the invention, provision can also be made for the wear sensor to be arranged outside the running surface of the friction lining. This makes it possible for the wear sensor to be arranged outside areas that are particularly subject to thermal loads.

[0039] It can also be advantageous to develop the invention in such a way that the multi-disk brake is designed as a wet-running multi-disk brake. This can achieve the advantage that, for example, a corresponding fluid in the brake cooling circuit can be used for heat dissipation. In this context, it is particularly advantageous if the brake cooling circuit is integrated into a thermal management system of the motor vehicle.

[0040] According to another preferred embodiment of the subject matter of the invention, it can be provided that the wear sensor is arranged on a rotationally rigid outer friction plate, which is accommodated in a likewise rotationally rigid outer friction plate carrier, wherein the outer friction plate carrier has a through-opening through which the first signal cable and the second signal cable pass. This makes it possible to provide a reliable and cost-effective cable guidance.

[0041] The object of the present invention can also be achieved by an electric axle drivetrain of a motor vehicle, wherein the electric axle drivetrain includes an electric motor having a rotor coupled to a transmission, and the transmission together with the electric motor forms a structural unit, wherein the electric axle drivetrain also includes a braking system according to any one of the above claims 1 to 9 and the brake housing together with the electric motor forms a structural unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The invention will be explained in more detail below with reference to the accompanying drawings without limiting the general concept of the invention.

[0043] The accompanying drawings show:

[0044] Figure 1 A motor vehicle with a brake system is shown in a schematic block diagram.

[0045] Figure 2 An electric drive train with a brake system is shown in a schematic axial section.

[0046] Figure 3 Detailed view of a multi-disk brake in axial section

[0047] Figure 4 Detailed view of the wear sensor in the outer friction plate in an axial section

[0048] Figure 5 A cross-sectional view showing the inner and outer friction plates. DETAILED DESCRIPTION

[0049] Figure 1 A brake system 1 is shown in a motor vehicle 3 which is electrically drivable by means of an electric machine 2 . The brake system has a brake cooling circuit 41 which is coupled to a heat exchanger 40 .

[0050] Figure 2 An electric axle drive train 20 of a motor vehicle 3 is shown, which comprises an electric machine 2 having a rotor 8 coupled to a transmission 21. The transmission 21 together with the electric machine 2 forms a structural unit 23. The electric axle drive train 20 also comprises a brake system 1, whose brake housing 9 together with the electric machine 2 forms a structural unit 24.

[0051] As from Figure 2 It is also apparent that the brake system 1 has a multi-disk brake 4 with a plurality of inner friction disks 5 and a plurality of outer friction disks 6 which can be brought into frictional engagement by means of a brake actuator 7 .

[0052] The electric motor 2 accommodated in the motor housing 52 also has a rotor 8, which has a rotor shaft 36 and is coupled to at least one wheel 10 of the motor vehicle 3 in a torque-transmitting manner. The wheel 10 can be decoupled from the electric motor 2 by means of a separating clutch 37. The multi-disk brake 4 is accommodated in a brake housing 9 and the inner friction plate 5 or the outer friction plate 6 is connected to the rotor 8 of the electric motor 2 in a torque-transmitting manner. A wear sensor 11 is provided on at least one of the inner friction plate 5 or the outer friction plate 6, by means of which the wear of the friction lining 12 on one of the inner friction plate 5 or the outer friction plate 6 can be detected. This is based on Figure 3-Figure 5 Elaborate in detail.

[0053] exist Figure 3In the embodiment shown in FIG. 1 , the wear sensor 11 is arranged on the axially outermost outer friction plate 6 at the axial end side opposite the switching piston 13. Here, the wear sensor 11 is fixed in a recess 14 formed in the axially outermost outer friction plate 6. Figure 3 It can also be seen that the wear sensor 11 is arranged on the rotationally rigid outer friction plate 6, which is accommodated in a likewise rotationally rigid outer friction plate carrier 25, wherein the outer friction plate carrier 25 has a through-opening 26, which is penetrated by the first signal cable 15 and the second signal cable 16. The friction plate pack formed by the inner friction plate 5 and the outer friction plate 6 and the fixed outer friction plate carrier 25 are axially supported at the axial side. The signal cables 15, 16 are guided through the through-opening 26 to a signal processing unit (not shown) outside the brake housing 9. The inner friction plate 5 is coupled to the inner friction plate carrier 28 in a rotationally rigid manner.

[0054] Figure 4 It is shown that the wear sensor 11 comprises a first signal cable 15 and a second signal cable 16, which extend at least partially in the axial direction through the recess 14, wherein the electrically conductive ends of the signal cables 15, 16 terminate in a common radial plane 17, which has an axial spacing a from the friction surface 18 of the corresponding outer friction plate 6 accommodating the wear sensor 11, so that the circuit between the first signal cable 15 and the second signal cable 16 is closed after the axial friction surface 18 is worn to the radial plane 17. The first signal cable 15 and the second signal cable 16 are fixed in the recess 14 by means of a potting compound 19.

[0055] Figure 4 In Figure a, the inner friction plate 5 and the outer friction plate 6 are shown in a new state, wherein the friction lining 12 is not worn. Figure 4 The maintenance state is shown in Figure b of . Here, the friction lining 12 is worn until the wear limit.

[0056] In the embodiment shown, the outer friction plate 6 is designed as a steel friction plate, in which a recess 14 for accommodating the wear sensor 11 is provided, and a first signal cable 15 and a second signal cable 16 are located in the recess. The two signal cables 15, 16 are arranged at a defined distance relative to each other. The two signal cables 15, 16 are shielded from external influences via an insulating member 27. The signal cables 15, 16 are made of a material with high electrical conductivity. On the side of the outer friction plate 6 facing the inner friction plate 5, the signal cables 15, 16 are fixed by means of a potting compound 19. The inner friction plate 5 is configured as a friction plate. The upper boundaries of the potting compound 19 and the sides of the signal cables 15, 16 facing the friction plate are at the same height. There is a potential difference between the signal cables 15, 16.

[0057] The height of the potting compound 19 and the signal cables 15, 16 relative to the surface of the outer friction lining 6 is selected so that a distance a is obtained. In the new state of the friction lining 12, the distance a represents the wear allowance of the friction lining 12. The air gap formed by the distance a insulates the signal cables 15, 16 from the steel carrier of the inner friction lining 5. As a result, a current flow between the first signal cable 15 and the second signal cable 16 is not possible.

[0058] In the maintenance state, i.e. when the wear margin is completely exhausted, the spacing a=0. In this state, the signal cables 15, 16 are in direct contact with the steel carrier of the inner friction plate 5. In the operating state, the steel carrier of the inner friction plate 5 acts as an electrical conductor. As a result, a current flow between the first signal cable 15 and the second signal cable 16 is possible.

[0059] exist Figure 5 6 shows the positioning of the wear sensor 11 on the outer friction lining 6. Here, the wear sensor 11 is positioned so that it is arranged outside the running surface of the friction lining 12.

[0060] The present invention is not limited to the embodiments shown in the drawings. The above description should therefore not be considered restrictive, but illustrative. The following claims should be understood as the presence of the features proposed in at least one embodiment of the present invention. This does not exclude the presence of other features. If the claims and the above description define a "first" feature and a "second" feature, this naming is used to distinguish between two features of the same type without defining a priority order.

[0061] Reference numerals list

[0062] 1 Braking system

[0063] 2 Motor

[0064] 3 Motor vehicles

[0065] 4-disc brake

[0066] 5 Inner friction plate

[0067] 6 External friction plate

[0068] 7 Brake actuator

[0069] 8 Rotor

[0070] 9 Brake housing

[0071] 10. Wheel

[0072] 11 Wear sensor

[0073] 12 Friction lining

[0074] 13 Switching piston

[0075] 14 recess

[0076] 15 Signal cable

[0077] 16 Signal Cable

[0078] 17 Radial plane

[0079] 18 Friction surface

[0080] 19 potting compound

[0081] 20 Axle Powertrain

[0082] 21 Transmission

[0083] 23 units

[0084] 24 units

[0085] 25 Outer friction plate carrier

[0086] 26 Through opening

[0087] 27 Insulation

[0088] 28 Inner friction plate carrier

[0089] 36 Rotor shaft

[0090] 37 Separate clutch

[0091] 40 Heat Exchanger

[0092] 41 Brake cooling circuit

[0093] 52 Motor housing

Claims

1. A brake system (1) for a motor vehicle (3) which can be electrically driven by means of an electric motor (2), wherein the brake system (1) has a plate brake (4) with a plurality of inner friction plates (5) and a plurality of outer friction plates (6), which can be brought into frictional engagement by means of a brake actuator (7), and the electric motor (2) has a rotor (8) which is coupled to at least one wheel (10) of the motor vehicle (3) in a torque-transmitting manner, It is characterized in that The disk brake (4) is accommodated in a brake housing (9) and the inner friction plate (5) or the outer friction plate (6) is connected to the rotor (8) of the motor (2) in a torque-transmitting manner, and a wear sensor (11) is provided on at least one of the inner friction plate (5) or the outer friction plate (6), by means of which the wear of the friction lining (12) on one of the inner friction plate (5) or the outer friction plate (6) can be detected.

2. The brake system (1) according to claim 1, It is characterized in that The wear sensor (11) is arranged on the axially outermost inner friction plate (5) or outer friction plate (6).

3. The brake system (1) according to claim 1 or 2, It is characterized in that The wear sensor (11) is arranged on the outermost inner friction plate (5) or outer friction plate (6) located on the axial end side opposite to the switching piston (13).

4. The brake system (1) according to any one of the preceding claims, It is characterized in that The wear sensor (11) is fixed in a recess (14) which is formed in one of the inner friction plate (5) or the outer friction plate (6).

5. The brake system (1) according to claim 4, It is characterized in that The wear sensor (11) comprises a first signal cable (15) and a second signal cable (16), wherein the first signal cable and the second signal cable extend at least partially in an axial direction through the recess (14), wherein the electrically conductive ends of the signal cables (15, 16) terminate in a common radial plane (17), and the common radial plane has an axial distance a from a friction surface (18) of a corresponding inner friction plate (5) or outer friction plate (6) accommodating the wear sensor (11), so that after the friction surface (18) is axially worn to the radial plane (17), the circuit between the first signal cable (15) and the second signal cable (16) is closed.

6. The brake system (1) according to claim 4 or 5, It is characterized in that The first signal cable (15) and the second signal cable (16) are fixed in the recess (14) by means of a potting compound (19).

7. Braking system (1) according to any one of the preceding claims, It is characterized in that The wear sensor (11) is arranged outside the working surface of the friction lining (12).

8. Braking system (1) according to any one of the preceding claims, It is characterized in that The disk brake (4) is designed as a wet-running disk brake (4).

9. Braking system (1) according to any one of the preceding claims, It is characterized in that The wear sensor (11) is arranged on a torsion-resistant outer friction plate (6), and the torsion-resistant outer friction plate is accommodated in a likewise torsion-resistant outer friction plate carrier (25), wherein the outer friction plate carrier (25) has a through opening (26), and the through opening is penetrated by the first signal cable (15) and the second signal cable (16).

10. An electric axle drive train (20) of a motor vehicle (3), comprising an electric machine (2) having a rotor (8) coupled to a transmission (21), wherein the transmission (21) together with the electric machine (2) forms a structural unit (23), It is characterized in that The electric axle drive (20) further comprises a brake system (1) according to any one of the preceding claims, and the brake housing (9) together with the electric machine (2) forms a structural unit (24).

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