Brake system for electrically drivable motor vehicle

Abstract

The invention relates to a brake system (1) for an electrically drivable motor vehicle (2), comprising an electric machine (3) having a rotor (4) which can be coupled in a torque-transmitting manner to a brake device (5) and to at least one vehicle wheel (6), the brake system (1) further comprising a service brake system (7) which is coupled in a torque-transmitting manner to the brake device (5) and to the at least one vehicle wheel (6). The invention relates to a service brake system (1) for applying a brake torque in a wheel-selective manner to vehicle wheels (6) of at least a first vehicle axle (8), the brake system (1) comprising a system controller (9) which, in the presence of an input brake signal (10), in particular depending on a current operating state of the motor vehicle (2), controls the brake torque in a wheel-selective manner to the vehicle wheels (6) of at least a first vehicle axle (8). A first control signal (11) representing a deceleration torque is transmitted to the brake device (5), and / or a second control signal (12) representing a deceleration torque is transmitted to the electric machine (3), and / or a third control signal (13) representing a deceleration torque is transmitted to the service brake system (7).

Description

Technical Field

[0001] The invention relates to a braking system for an electrically drivable motor vehicle, the braking system comprising an electric motor having a rotor which can be coupled to a braking device and at least one vehicle wheel in a torque-transmitting manner, wherein the braking system also comprises a service braking system for applying a braking torque in a wheel-selective manner to the vehicle wheels of at least a first vehicle axle. Background Art

[0002] Electric motors are increasingly used to drive motor vehicles to create an alternative to internal combustion engines that require fossil fuels. Great efforts have been made to improve the suitability of electric drives for everyday use and also to provide users with the driving comfort they are accustomed to. A detailed description of electric drives can be found by way of example in an article published by Erik Schneider, Frank Fickl, Bernd Cebulski and Jens Liebold in the German automobile magazine ATZ, Volume 113, May 2011, pages 360 to 365, the title of which is: Hochintegrativ und Flexibel Elektrische Antriebseinheit für E-Fahrzeuge [Highly Integrative and Flexible Electric Drive Unit for E-Vehicles (Highly Integrated and Flexible Electric Drive Unit for Electric Vehicles)]. The article describes a drive unit for an axle of a vehicle, the drive unit comprising an electric motor, which is arranged coaxially with a bevel gear differential.

[0003] Motor vehicles of this type with a hybrid or electrified drive train can not only accelerate but also brake with the aid of an electric machine. For example, during a braking process, the electric machine is operated as a generator and the recovered energy is used to charge the battery. However, for safety reasons, additional mechanical braking devices are still required. For drives close to the wheels, such as wheel hub motors or electric axles, this leads to more difficult installation space conditions.

[0004] In particular, vehicles comprising electric wheel hub drives, so-called electric wheel drives, usually use brakes with plate elements to brake the vehicle. However, disc brakes with floating calipers, disc brakes with fixed calipers, drum brakes and multi-disc brakes are also known.

[0005] For example, DE 10 2019 120 409 A1 discloses a braking device for a wheel hub drive assembly, in which the brake mating part fixed relative to the circumferential direction has a cooling channel. The axially movable brake mating part is actuated via a brake cylinder. The brake mating part that can move in the circumferential direction is designed as a plate-shaped carrier. Summary of the Invention

[0006] Therefore, an object of the present invention is to provide an optimized braking system for an electrically drivable motor vehicle.

[0007] This object is achieved by a braking system for an electrically drivable motor vehicle, the braking system comprising an electric motor having a rotor, the rotor being connectable in a torque-transmitting manner to a braking device and at least one vehicle wheel, wherein the braking system further comprises a service braking system for selectively applying a braking torque to the vehicle wheels of at least a first vehicle axle, and wherein the braking system has a system controller which, in the presence of an input braking signal, in particular depending on the current driving state of the motor vehicle, transmits a first control signal representing a deceleration torque to the braking device and / or transmits a second control signal representing a deceleration torque to the electric motor and / or transmits a third control signal representing a deceleration torque to the service braking system.

[0008] The advantage of this is that the best deceleration of the motor vehicle can be achieved depending on the driving state, in particular by using the braking device connected to the electric motor.

[0009] Depending on the operating state of the vehicle, an ideal braking can also be selected from parameters such as driving stability, thermal requirements, readiness for braking (pre-safety), and battery charge state. This complements the vehicle's ability to optimally utilize kinetic energy at any given time without compromising safety.

[0010] The braking system includes an electric motor. The braking device is intended for a motor vehicle that can be electrically driven by means of the electric motor. The electric motor, within the meaning of the present application, is used to convert electrical energy into mechanical energy and / or convert mechanical energy into electrical energy, and generally includes a stationary part known as the stator, columnar part or stationary anchor, and a part known as the rotor or runner that is arranged to be movable relative to the stationary part. In connection with the present invention, the electric motor can be particularly designed as a rotary machine. In the case of such an electric rotary machine, a distinction is made in particular between a radial flow machine and an axial flow machine. The radial flow 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 flow machine, the magnetic field lines extend in the axial direction in the air gap formed between the rotor and the stator. In the context of the present invention, the electric motor is particularly arranged for use in the driveline of a hybrid motor vehicle or a fully electric drive motor vehicle. In particular, the electric motor is dimensioned such that a vehicle speed of more than 50 km / h, preferably more than 80 km / h, and particularly more than 100 km / h can be achieved. The electric motor particularly preferably has an output of more than 30 kW, preferably more than 50 kW, and particularly more than 70 kW. In addition, it is preferred that the electric motor provides a speed of more than 5000 rpm, particularly preferably more than 10,000 rpm, very particularly preferably more than 12,500 rpm.

[0011] The electric motor can have a housing, which is also referred to as the motor housing. The motor housing encloses the electric motor. The motor housing can also accommodate the control and power electronics unit, and preferably can also accommodate at least a part of the braking system. The motor housing can also be part of a cooling system for the electric motor and can be designed such that the cooling fluid can be supplied to the electric motor via the motor housing and / or heat can be dissipated to the outside via the motor housing surface. In addition, the motor housing protects the electric motor and any electronics from external mechanical and / or chemical influences. In particular, the motor housing of the electric motor can be made of a metallic material. Advantageously, the motor housing can be formed from a metallic casting material such as gray cast iron or cast steel. In principle, it is also conceivable that the motor housing is formed entirely or partly from plastic. The motor housing of the electric motor can also be designed as one piece or several parts.

[0012] The rotor is the rotating (swirling) part of the electric motor. The rotor particularly includes a rotor shaft and one or more rotor bodies formed by a stack of rotor laminations that are arranged in a rotationally fixed manner on the rotor shaft. The rotor shaft can be hollow, which on the one hand results in weight reduction and on the other hand allows the supply of lubricant or coolant to the rotor body. In particular, the rotor shaft can be coupled to the brake shaft of the braking device.

[0013] The electric machine can preferably be coupled to a transmission which is designed to generate a drive torque for a motor vehicle. The drive torque is particularly preferably a main drive torque such that the motor vehicle is driven only by this drive torque.

[0014] In particular, it can be provided that the electric machine and the transmission are arranged in a common transmission housing. Alternatively, the electric machine can of course also have a motor housing and the transmission can of course also have a transmission housing, whereupon a structural unit can then be realized by fixing the transmission assembly relative to the electric machine. This structural unit is sometimes also referred to as an electric axle. The transmission housing is preferably formed from a metallic material, particularly preferably from aluminum, gray cast iron or cast steel, in particular by means of a one-piece forming process such as casting or die-casting. However, in principle, it will also be possible to form the transmission housing from a plastic material. The transmission housing can particularly preferably have a cup-shaped basic shape such that the electric machine and the transmission can be inserted into the transmission housing via the open end face of the transmission housing.

[0015] The electric machine preferably has a motor housing and / or the transmission has a transmission housing, whereupon the structural unit can then be realized by fixing the transmission relative to the electric machine. The transmission housing is a housing for accommodating the transmission. The transmission housing has the following tasks: guiding the existing shafts via bearings and giving the wheels (cam disks, where applicable) the degrees of freedom required under all loads without impeding the rotation and possible path movement of the wheels, and absorbing bearing forces and support torques. The transmission housing can be designed as a single-shell or multi-shell, i.e., non-separated or separated. In particular, the transmission housing should be able to suppress noise and vibration and safely absorb hydraulic fluid. The transmission housing is preferably formed from a metallic material, particularly preferably from aluminum, gray cast iron or cast steel, in particular by means of a one-piece forming process such as casting or die-casting.

[0016] 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 planet gears and a ring gear, the plurality of planet gears meshing with the sun gear, being rotatably mounted in a planet gear carrier, and the plurality of planet gears rotating around the sun gear, the ring gear being arranged coaxially relative to the sun gear, and the planet gears rolling in the ring gear.

[0017] The transmission can also have a differential transmission. The differential transmission is a planetary transmission having one drive and two outputs. The differential transmission generally has the following function: driving the two vehicle wheels of a motor vehicle such that the two vehicle wheels can rotate at different speeds during a turn but have the same driving force.

[0018] In order to implement different drive modes or operating modes for a motor vehicle, one or more disengaging clutches can be arranged in the torque path between the electric motor and the vehicle wheels. For example, a disengaging clutch can be arranged between the output of the electric motor and the input of the transmission, such that the electric motor can be disconnected from the transmission, thereby allowing the motor vehicle to operate in a coasting mode. It is also conceivable to arrange the disengaging clutch between the output of the transmission and one or more vehicle wheels, thereby also allowing the motor vehicle to operate in a coasting mode. Finally, the disengaging clutch can also be arranged between the input of the braking device and the output of the electric motor, which allows the braking device to be completely disconnected from the electric motor.

[0019] For the purposes of the present application, a motor vehicle is a land vehicle that is moved by machine power and is not restricted to railway tracks. The motor vehicle can be selected, for example, from the group consisting of passenger cars, trucks, scooters, light motor vehicles, motorcycles, buses / coaches or tractors.

[0020] For example, the system controller has, in particular, a wired signal input or a wireless signal input for receiving, in particular, electrical signals, such as sensor signals. In addition, the control unit preferably also has a wired signal output or a wireless signal output for transmitting signals, in particular electrical signals, to actuators of, for example, the braking device, the service braking system and / or the electric motor.

[0021] Open-loop control operations and / or closed-loop control operations can be performed within the system controller. Highly particularly preferably, the system controller comprises hardware that is designed to run software. The system controller preferably comprises at least one electronic processor for executing the program sequences defined in the software.

[0022] The system controller can also have one or more electronic memories in which the data contained in the signals transmitted to the control unit can be stored and read out again. In addition, the system controller can have one or more electronic memories in which data can be stored in a modifiable and / or non-modifiable manner.

[0023] The system controller may include a plurality of control units, which are particularly arranged to be spatially separated from each other. The control units are also referred to as electronic control units (ECUs) or electronic control modules (ECMs), and preferably have an electronic microcontroller, which is used to perform computational operations for processing data, particularly preferably using software to perform computational operations for processing data. The control units may preferably be interconnected with each other such that wired data exchange and / or wireless data exchange between the control units is possible. In particular, for example, the control units may also be interconnected with each other via a bus system such as a CAN bus or a LIN bus.

[0024] According to an advantageous embodiment of the invention, it may be provided that the system controller includes a central control device and a first control unit, which receives a first control signal from the central control device and controls the braking device at least with respect to its braking characteristics, and the system controller includes a second control unit, which receives a second control signal from the central control device and controls the electric motor at least with respect to its braking characteristics, and

[0025] the system controller includes a third control unit, which receives a third control signal from the central control device and controls the service braking system at least with respect to its braking characteristics.

[0026] The advantage of this design is that each module configured to generate braking torque can be controlled via its own control unit. In particular, this can reduce the computational power required by the central control device and also contribute to an improved distribution of computational power.

[0027] According to another preferred further improvement of the invention, it may also be provided that the system controller includes a third control unit, which receives a third control signal from the central control device and controls the service braking system at least with respect to its braking characteristics, and the system controller includes a fourth control unit, which receives a fourth control signal from the central control device, and transmits a first control signal representing the deceleration torque to the braking device and transmits a second control signal representing the deceleration torque to the electric motor, and the fourth control unit controls both the braking device and the electric motor at least with respect to the respective braking characteristics. This enables the control functions of the "electric motor / braking device" assembly to be bundled, which is particularly advantageous if the electric motor and the braking device form a structural unit.

[0028] Furthermore, according to a similar advantageous embodiment of the present invention, it can be provided that the system controller includes a fifth control unit that receives a fifth control signal from the central control device and transmits a third control signal representing the deceleration torque to the service brake system and controls the service brake system at least with respect to its braking characteristics. The system controller includes a fourth control unit that receives a fourth control signal from the third control unit and transmits a first control signal representing the deceleration torque to the braking device and a second control signal representing the deceleration torque to the electric motor, and the fourth control unit controls both the braking device and the electric motor at least with respect to their respective braking characteristics. The advantageous effect of this design is due to the fact that the distribution of the braking torque is largely carried out by the control unit assigned to the service brake system.

[0029] According to another particularly preferred embodiment of the present invention, it can be provided that the second control signal representing the deceleration torque sets the electric motor to the generator mode, so that the braking effect of the electric motor can be further improved.

[0030] In addition, the present invention can be further developed such that the system controller and the central control device and the control units form a structural unit. The advantage of this design is that a compact control unit can be provided for the braking system. In particular, one of the control units in the central control device and the control units, preferably all the control units, can be designed on a common circuit board.

[0031] In an equally preferred embodiment of the present invention, it can also be provided that the braking device is accommodated in a brake housing that forms a structural unit with the electric motor. This means that the increasing demand for reducing or completely avoiding the emissions of brake dust, which usually appears as particulate matter, can be met.

[0032] The braking device is preferably arranged in a brake housing. The brake housing encloses the braking device. The brake housing may also accommodate one or more brake actuators. The brake housing may also be part of a cooling system and may be designed such that cooling fluid can be supplied to the braking system via the brake housing and / or heat can be dissipated to the outside via the housing surface. The brake housing also protects the braking device from external mechanical and / or chemical influences. The brake housing may in particular be formed from a metallic material. Advantageously, the brake housing may be formed from a metallic casting material such as grey cast iron or cast steel. In principle, it is also conceivable to form the brake housing completely or partly from plastic. In addition, the brake housing may be designed as one piece or as several parts. The brake housing may also be designed completely or partly as part of the motor housing of an electric motor or as part of the transmission housing of a transmission coupled to the electric motor. Preferably, the brake housing and the motor housing or the transmission housing form a single structural unit. For example, the brake housing may be screwed to the motor housing or the transmission housing. The brake housing is preferably designed such that dust generated during braking cannot escape from the brake housing. This prevents unwanted contamination of the environment by brake dust. By encapsulating the braking system in this way, brake noise can also be reduced. Another advantageous aspect of this encapsulation is that the braking performance of the braking system is independent of the weather conditions outside the motor vehicle.

[0033] It may also be advantageous to develop the invention such that the fourth control unit forms a structural unit with the electric motor and / or the brake housing, which is particularly advantageous in terms of installation.

[0034] According to another preferred embodiment of the object of the invention, it may be provided that the braking device comprises one or more friction brakes, which are particularly selected from the group of multi-disc brakes, disc brakes and / or drum brakes.

[0035] The braking device may be designed as a disc brake. The brake disc is the rotating part of the disc brake, on the end face of which the brake shoes act releasably in order to decelerate the rotational movement of the brake disc by means of frictional connection during operation of the disc brake. The brake disc preferably has a brake disc body.

[0036] The brake disc may preferably be formed from cast metal, in particular grey cast iron, ductile cast iron or cast steel, and is then preferably machined by turning and / or milling. It is also possible to use silicon carbide reinforced with carbon fibres and / or ceramic materials reinforced with carbon fibres in order to achieve a particularly low brake disc weight. In particular for providing the brake disc in a particularly cost-effective manner, it is also conceivable to stamp out the brake disc from a sheet.

[0037] The brake disc preferably has a hollow cylindrical space shape, the axial extension of which is significantly smaller than its diameter. The brake disc can be made as a single part or several parts. In the case of a multi-disc brake disc, the individual brake disc elements can preferably be arranged in layers in the axial direction, thereby creating a sandwich structure.

[0038] The brake disc body is part of the brake disc, and the brake shoe acts frictionally on the brake disc body to reduce the rotational speed of the brake disc. The brake disc body can have a plurality of brake disc cooling channels, which can be specifically used to dissipate heat and / or brake dust from the brake disc body.

[0039] In addition, the braking device can have a shaft connection. The shaft connection of the brake disc connects the brake disc body to the rotating shaft to be braked, which is also called the brake shaft. The shaft connection can be designed as a separate component that is arranged in the torque flow between the brake disc body and the shaft to be braked, or the shaft connection can be designed as a connection between the brake disc body and the shaft to be braked. Therefore, the shaft to be braked and the shaft connection can be formed as one piece, especially integrally formed. In principle, it is also conceivable that the shaft connection and the brake disc body are designed as one piece. It is also preferable that the shaft to be braked, the shaft connection, and the brake disc body are formed as one piece, especially integrally formed. For example, the shaft connection can also be produced by means of form-fit locking, friction locking, and / or material locking between the shaft to be braked and the brake disc body. For example, the shaft connection can be made by means of a press fit, splines, or welding.

[0040] The disc brake can have a hydraulic brake disc cooling system. The hydraulic brake disc cooling system uses a brake disc cooling fluid to cool the brake disc. In this case, the brake disc cooling fluid can act at least partially on the brake disc and / or be fed through the brake disc. Preferably, the hydraulic brake disc cooling system is designed such that the brake disc cooling fluid cannot reach the friction surface between the brake shoe and the brake disc body.

[0041] For this purpose, the hydraulic brake disc cooling system can have at least one brake disc cooling channel, but preferably a plurality of brake disc cooling channels, in which the brake disc cooling fluid is guided.

[0042] It is also preferable that the hydraulic brake disc cooling system is connected to a brake disc cooling circuit, within which the frictional heat absorbed by the brake disc cooling fluid is dissipated from the disc brake and fed to a radiator, such as a heat exchanger. The brake disc cooling circuit can preferably form part of the brake cooling circuit of the thermal management system. Most preferably, the brake disc cooling circuit is the brake cooling circuit of the thermal management system.

[0043] To form a frictional connection between the brake shoe and the brake disc, the brake shoe, in particular by means of its brake lining, is preferably axially pressed against the brake disc by means of a brake actuator.

[0044] The function of a multi-disc brake is to form a releasable frictional engagement connection between the brake shaft and the connection structure, which is usually arranged in a non-rotatable manner for this purpose to support the braking torque. For this purpose, the alternately arranged inner and outer discs of the disc pack can be brought into non-form-fitting or frictional contact by means of an assembly process via their respective brake linings by axial displacement and compression, such that the inner discs are arranged to rotate in a frictionally engaged manner relative to the outer discs about the common axis of rotation of the corresponding disc pack, or in the case of full frictional engagement are arranged to be rotationally fixed relative to each other. On the other hand, if the inner and outer discs are axially pushed away from each other by a disengagement process, there is no longer any non-form-fitting contact between the inner and outer discs, such that the inner and outer discs can rotate freely relative to each other and thus no torque or braking torque is transmitted between the inner and outer discs.

[0045] A multi-disc brake typically comprises at least two inner discs and / or two outer discs. The inner discs are preferably arranged in a non-rotatable manner on an inner multi-disc carrier, and the outer discs are preferably arranged in a non-rotatable manner on an outer multi-disc carrier. The inner multi-disc carrier is preferably connected to the brake shaft, and the outer multi-disc carrier is preferably connected in a non-rotatable manner to the connection structure, or vice versa.

[0046] The inner and outer discs form the disc pack of the multi-disc brake. In the disc pack, a plurality of inner and outer discs are preferably arranged alternately in the axial direction. The torque or braking torque that can be transmitted by the multi-disc brake between the inner and outer discs can be adjusted by the number and design of the inner and outer discs.

[0047] The inner disc has the function of transmitting torque from the outer disc to the inner multi-disc carrier, in particular in a non-form-fitting or frictionally engaged manner. The inner disc can be designed in particular as an annular disc. The inner disc can be connected in a non-rotatable manner to the inner multi-disc carrier of the multi-disc brake. It can also be provided that the inner disc is axially displaced relative to the inner multi-disc carrier, for example by means of a corresponding toothing, to form a frictional connection with the outer disc.

[0048] The outer disc has the function of transmitting torque from the inner disc to the outer multi-disc carrier, in particular in a non-form-fitting or frictionally engaged manner. The outer disc can be designed in particular as an annular disc. The outer disc can be connected in a non-rotatable manner to the outer multi-disc carrier of the multi-disc clutch. It can also be provided that the outer disc is axially displaced relative to the outer multi-disc carrier, for example via a corresponding toothing, to form a frictional connection with the inner disc. For example, the outer multi-disc carrier can be designed as an outer disc clutch cage.

[0049] The disk pack can be accommodated in one or more multi-disk carriers and can in particular also be guided for linear movement. For this purpose, the inner disks can be accommodated in inner multi-disk carriers and the outer disks can be accommodated in outer multi-disk carriers. In order to form a linearly displaceable offset of the inner disks relative to the outer disks (or in order to form a linearly displaceable offset of the outer disks relative to the inner disks), the inner disks can be connected to the inner multi-disk carriers via internal spline teeth and / or the outer disks can be connected to the outer multi-disk carriers in a torque-transmitting manner via external spline teeth.

[0050] The multi-disk brake can preferably include a spring element. The spring element has the task of moving the inner and outer disks relative to one another to a predetermined position using spring force. This predetermined position typically corresponds to the "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 disks are pressed against one another or released by the spring element.

[0051] The multi-disk brake can also have a shift piston. The shift piston has the function of converting the engagement process or disengagement process specified by the brake actuator into an axial displacement of the inner and / or outer disks for the purpose of establishing a frictional connection during braking or releasing the frictional connection when the multi-disk brake is released.

[0052] In particular, the brake actuator has the function of actuating the braking device, i.e., setting the braking device into a frictionally engaged operating state and a released operating state from the frictional connection. In particular, the brake actuator can be actuated pneumatically, hydraulically, by an electric motor, mechanically, electromagnetically, or by any combination of these. The brake actuator is preferably configured as an electromechanical brake actuator.

[0053] Finally, the invention can also be advantageously designed such that the service brake system is designed to apply the braking torque in a wheel-selective manner to the vehicle wheels of a first vehicle axle and the vehicle wheels of a second vehicle axle, which further improves the braking performance of the braking system. Description of the Drawings

[0054] The invention is explained in more detail below with reference to the drawings without limiting the general concept of the invention.

[0055] In the drawings:

[0056] Figure 1 A braking system with an electric powertrain is shown in a schematic axial sectional view,

[0057] Figure 2 A first embodiment of the braking system is shown in a schematic block circuit diagram,

[0058] Figure 3The second embodiment of the braking system is shown in a schematic block circuit diagram.

[0059] Figure 4 The third embodiment of the braking system is shown in a schematic block circuit diagram. Detailed Embodiment

[0060] Figure 1 Shown is a braking system 1 for an electrically drivable motor vehicle 2, which braking system includes an electric machine 3 having a rotor 4, which rotor can be coupled in a torque-transmitting manner to a braking device 5 and at least one vehicle wheel 6. In Figure 1 the exemplary embodiment shown, the braking system 1 is integrated into the electric axle drivetrain 27 of the motor vehicle 2. The electric machine 3, the braking device 5 and the transmission device 25 form a single structural unit. For example, in order to enable the motor vehicle to coast, a disengaging clutch 24 is arranged between the vehicle wheel 6 and the electric machine 3.

[0061] The braking device 5 is configured as a wet-running multi-disc brake, which multi-disc brake is coupled to a brake cooling circuit 28, and heat can be dissipated from the braking device 5 by means of this brake cooling circuit. The braking device can be actuated by means of a brake actuator 26, which brake actuator is an electric motor connected to a spindle drive in the example shown. Figure 1 It is clearly shown that the braking device 5 is closed to immediately apply a deceleration torque to the rotor 4 of the electric machine 3 and to the vehicle wheel 6. The braking device 5 is accommodated in a brake housing 22, which brake housing forms a structural unit with the electric machine 3.

[0062] The braking system 1 also has a service braking system 7 for applying the braking torque in a wheel-selective manner to the vehicle wheels 6 of the first vehicle axle 8 and the vehicle wheels 6 of the second vehicle axle 23.

[0063] In this configuration, three different deceleration torques can thus act on one or more of the vehicle wheels 6: the deceleration torque generated by the braking device 5, the deceleration torque generated by the electric machine 3 and / or the deceleration torque generated by the service braking system 7. Depending on the driving situation and the deceleration requirement, these three available deceleration torques can be combined and applied in a controlled manner.

[0064] To control these deceleration torques, the braking system 1 has a system controller 9, which system controller, in the presence of an input braking signal 10, in particular according to the current driving state of the motor vehicle 2, transmits a first control signal 11 representing the deceleration torque to the braking device 5 and / or transmits a second control signal 12 representing the deceleration torque to the electric machine 3 and / or transmits a third control signal 13 representing the deceleration torque to the service braking system 7.

[0065] The second control signal 12 representing the deceleration torque sets the electric motor 3 to the generator mode.

[0066] Figure 2 Fig. 4 shows a first embodiment of the braking system 1, in which the system controller 9 comprises a central control device 20 and a first control unit 14, which receives a first control signal 11 from the central control device 20 and controls the braking device 5 at least with respect to its braking characteristics. The system controller 9 also has a second control unit 15, which receives a second control signal 12 from the central control device 20 and controls the electric motor 3 at least with respect to its braking characteristics. Finally, the system controller 9 also has a third control unit 16, which receives a third control signal 13 from the central control device 20 and controls the service braking system 7 at least with respect to its braking characteristics.

[0067] Thus, the central control device 20 receives an input braking signal 10 which should trigger the braking. Then, the central control device 20 distributes the requested deceleration torque, which is distributed to the braking device 5, the electric motor 3 and the service braking system 7. The distribution strategy is stored on the central control device 20. Depending on the boundary conditions, the central control device 20 determines what the respective shares of the total deceleration torque of the braking device 5, the electric motor 3 and the service braking system 7 are.

[0068] Figure 3 Fig. 5 shows an alternative form of the braking system 1, in which the system controller 9 comprises a third control unit 16, which receives a third control signal 13 from the central control device 20 and controls the service braking system 7 at least with respect to its braking characteristics. The system controller 9 also has a fourth control unit 17, which receives a fourth control signal 18 from the central control device 20 and transmits a first control signal 11 representing the deceleration torque to the braking device 5 and a second control signal 12 representing the deceleration torque to the electric motor 3, and the fourth control unit 17 controls both the braking device 5 and the electric motor 3 at least with respect to the respective braking characteristics.

[0069] Thus, the braking allocation is carried out, i.e. the central control device 20 distributes the requested vehicle braking torque into the torque generated by the regeneration of the electric motor 3 and the braking device 5 and the torque generated by the friction brakes of the service braking system 7. Then, the third control unit 16 distributes to the friction brakes associated with the service braking system 7, which are arranged on the vehicle wheels 6 of the motor vehicle 2. Then, the fourth control unit 17 distributes the requested regenerative braking torque to the electric motor 3 and the braking device 5. The distribution strategy is stored on the fourth control unit 17.

[0070] Figure 4A third variant of the braking system 1 is shown herein. Here, the system controller 9 has a fifth control unit 21 which receives a fifth control signal 19 from the central control device 20 and transmits a third control signal 13 representing the deceleration torque to the service braking system 7 and controls the service braking system 7 at least with respect to its braking characteristics. In addition, the system controller 9 has a fourth control unit 17 which receives a fourth control signal 18 from the fifth control unit 21 and transmits a first control signal 11 representing the deceleration torque to the braking device 5 and a second control signal 12 representing the deceleration torque to the electric motor 3, and the fourth control unit 17 controls both the braking device 5 and the electric motor 3 at least with respect to their respective braking characteristics.

[0071] Therefore, the braking distribution strategy between the regenerative braking torque (electric motor 3 and braking device 5) and the braking torque generated by the friction brake of the service braking system 7 is stored in the fifth control unit 21. Then, the fourth control unit 17 distributes the requested regenerative braking torque back to the electric motor 3 and the braking device 5. The corresponding distribution strategy is stored in the fourth control unit 17.

[0072] Figures 2 to 4 It is shown that the system controller 9 and the central control device 20 and the control units 14, 15, 16, 17, 21 form a structural unit. Of course, it will also be conceivable that the central control device 20 and the control units 14, 15, 16, 17, 21 are separate components. It may also be advantageous for the fourth control unit 17 to form a structural unit with the electric motor 3 and / or the brake housing 22.

[0073] The present invention is not limited to the embodiments shown in the drawings. Therefore, the above description should not be regarded as restrictive, but rather as illustrative. The appended claims should be understood to mean that the stated features exist in at least one embodiment of the present invention. This does not exclude the existence of other features. When the claims and the above description define a "first" feature and a "second" feature, such naming is used to distinguish between two features of the same type and does not define a priority order.

[0074] List of reference numerals

[0075] 1 Braking system

[0076] 2 Motor vehicle

[0077] 3 Electric motor

[0078] 4 Rotor

[0079] 5 Braking device

[0080] 6 Vehicle wheel

[0081] 7 Service braking system

[0082] 8 Vehicle axle

[0083] 9 System controller

[0084] 10 Input braking signal

[0085] 11 Control signal

[0086] 12 Control signal

[0087] 13 Control signal

[0088] 14 Control unit

[0089] 15 Control unit

[0090] 16 Control unit

[0091] 17 Control unit

[0092] 18 Control signal

[0093] 19 Control signal

[0094] 20 Control device

[0095] 21 Control unit

[0096] 22 Brake housing

[0097] 23 Vehicle axle

[0098] 24 Disengaging clutch

[0099] 25 Transmission

[0100] 26 Brake actuator

[0101] 27 Axle drive train

[0102] 28 Brake cooling circuit

Claims

1. A braking system (1) for an electrically drivable motor vehicle (2), the braking system comprising an electric machine (3) having a rotor (4), the rotor being torque-transmittingly connectable to a braking device (5) and at least one vehicle wheel (6), wherein, The braking system (1) further includes a service braking system (7) which is used to apply braking torque to the vehicle wheels (6) of at least a first vehicle axle (8) in a wheel-selective manner. It is characterized in that the braking system (1) includes a system controller (9) which, when there is an input braking signal (10), in particular according to the current driving state of the motor vehicle (2), transmits a first control signal (11) representing a deceleration torque to the braking device (5), and / or transmits a second control signal (12) representing a deceleration torque to the electric motor (3), and / or transmits a third control signal (13) representing a deceleration torque to the service braking system (7).

2. The braking system (1) according to claim 1, It is characterized in that the system controller (9) includes a central control device (20) and a first control unit (14). The first control unit receives the first control signal (11) from the central control device (20) and controls the braking device (5) at least with respect to the braking characteristics of the braking device, and the system controller (9) includes a second control unit (15). The second control unit receives the second control signal (12) from the central control device (20) and controls the electric motor (3) at least with respect to the braking characteristics of the electric motor, and the system controller (9) includes a third control unit (16). The third control unit receives the third control signal (13) from the central control device (20) and controls the service braking system (7) at least with respect to the braking characteristics of the service braking system.

3. The braking system (1) according to claim 1, It is characterized in that the system controller (9) includes a third control unit (16). The third control unit receives the third control signal (13) from the central control device (20) and controls the service braking system (7) at least with respect to the braking characteristics of the service braking system, and the system controller (9) includes a fourth control unit (17). The fourth control unit receives a fourth control signal (18) from the central control device (20), transmits the first control signal (11) representing a deceleration torque to the braking device (5) and transmits the second control signal (12) representing a deceleration torque to the electric motor (3), and the fourth control unit (17) controls both the braking device (5) and the electric motor (3) at least with respect to the corresponding braking characteristics.

4. The braking system (1) according to claim 1, It is characterized in that The system controller (9) includes a fifth control unit (21), which receives a fifth control signal (19) from the central control device (20) and transmits the third control signal (13) representing the deceleration torque to the service brake system (7), and the fifth control unit controls the service brake system (7) at least with respect to the braking characteristics of the service brake system, and The system controller (9) includes a fourth control unit (17), which receives a fourth control signal (18) from the fifth control unit (21), transmits the first control signal (11) representing the deceleration torque to the brake device (5), and transmits the second control signal (12) representing the deceleration torque to the electric motor (3), and the fourth control unit (17) controls both the brake device (5) and the electric motor (3) at least with respect to the corresponding braking characteristics.

5. The brake system (1) according to any one of the preceding claims, characterized in that, The second control signal (12) representing the deceleration torque sets the electric motor (3) to the generator mode.

6. The brake system (1) according to any one of the preceding claims, characterized in that, The system controller (9) and the central control device (20) and the control units (14, 15, 16, 17, 21) form a structural unit.

7. The brake system (1) according to any one of the preceding claims, characterized in that, The brake device (5) is received in a brake housing (22), and the brake housing and the electric motor (3) form a structural unit.

8. The brake system (1) according to any one of the preceding claims, characterized in that, The fourth control unit (17) and the electric motor (3) and / or the brake housing (22) form a structural unit.

9. The brake system (1) according to any one of the preceding claims, characterized in that, The brake device (5) includes one or more friction brakes, and the one or more friction brakes are particularly selected from the group consisting of multi-disc brakes, disc brakes, and / or drum brakes.

10. The brake system (1) according to any one of the preceding claims, characterized in that, The service brake system (7) is designed to apply braking torque to the vehicle wheels (6) of the first vehicle axle (8) and the vehicle wheels (6) of the second vehicle axle (23) in a wheel-selective manner.

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