Driving dynamics system, vehicle and method for operating driving dynamics system

Abstract

The invention relates to a driving dynamics system for a vehicle, comprising: at least one wheel brake (RB1, RB2, RB3, RB4) for dissipative braking of one wheel of the vehicle; at least one brake unit (EMB, EHB) associated with the at least one wheel brake (RB1, RB2, RB3, RB4) and configured for generating a dissipative brake torque by means of the at least one wheel brake (RB1, RB2, RB3, RB4); at least one electric traction motor (TM1, TM2, TM3, TM4) which can be controlled to generate a regenerative braking torque for at least one wheel or axle of the vehicle; and a central control unit (M-ECU domain), which is configured to actuate the at least one brake unit (EMB, EHB) and the at least one electric traction motor (TM1, TM2, TM3, TM4) for a braking function in combination with one another such that a combined braking torque can be generated by means of the at least one brake unit (EMB, EHB) and the at least one electric traction motor (TM1, TM2, TM3, TM4). In this case, the braking function relates to a control situation in which the base braking torque and the adjusted additional braking torque are controlled and / or adjusted at the same time; wherein a base braking torque is optionally generated by means of the at least one braking unit (EMB, EHB) and an adjusted additional braking torque is generated by means of the at least one electric traction motor (TM1, TM2, TM3, TM4); or a base braking torque is generated by at least one electric traction motor (TM1, TM2, TM3, TM4) and an adjusted additional braking torque is generated by at least one braking unit (EMB, EHB); or the at least one brake unit (EMB, EHB) and the at least one electric traction motor (TM1, TM2, TM3, TM4) each jointly generate a base brake torque and an adjusted additional brake torque.

Description

Technical Field

[0001] The invention relates to a driving dynamics system (FDS) having one (multiple) electric traction motors and a powerful central computer, wherein the one (multiple) electric traction motors and brake modules (EMB, EHB) are synchronously controlled via the central computer, so that the one (multiple) traction motors and one (multiple) brake modules (EMB, EHB) are jointly controlled with respect to basic braking and control operating functions. The invention also relates to a vehicle having a driving dynamics system and a method for operating a driving dynamics system.

[0002] Preferably, the brakes and the electric traction motor are combined in a wheel module or an electric axle module, wherein the wheel brakes and the electric traction motor are actuated synchronously via a further wheel module controller or axle module controller. Background Art

[0003] The automotive industry is undergoing a process of disruptive change. In addition to the increasing market penetration of electric vehicles, automated driving is also progressing through different levels, starting with: Level 3 - Highly Automated Driving (HAD), Level 4 - Fully Automated Driving (FAD) and Level 5 - Autonomous Driving (AD), with each level placing higher demands on the systems for regulating driving dynamics.

[0004] From level 4 (FAD), at least two times, preferably three times redundancy is expected for sufficient system availability, for example in the case of a pedal sensor with a "two out of three" rule. In addition, redundant wheel-individualized brake torque control is required for automated driving from level 3 and especially from level 4. In level 5 (AD), the steering wheel and the brake and accelerator pedals are completely omitted if necessary and the vehicle is controlled only via a central computer. Since the driver can no longer intervene via the brake pedal or through the steering wheel in the event of a system failure, a fail-safe two- or three-fold redundancy is required with degradation of all core functions of the brakes (brake boost, ABS, vehicle stabilization) and steering.

[0005] Furthermore, a domain structure is introduced, which has a controller / domain for chassis control, which includes braking, electric drive, steering and optionally also damping. Through central control, the vehicle manufacturer takes over the responsibility for the above-mentioned units and can therefore also optimally utilize synergies. However, the vehicle manufacturer must also ensure the required redundancy, because new requirements must be met due to the transfer of responsibility from the driver of the vehicle to the manufacturer of the vehicle. Furthermore, autonomous vehicles of level 3-5 should not stop on the shoulder of the lane; at least a limp home mode is more desirable, even continued operation in the event of partial failure, because autonomous vehicles strive for a long service life.

[0006] As friction brake systems, electrohydraulic brake systems (EHB for short) or electromechanical brakes (EMB for short) as well as foundation brakes with brake pads and brake discs are available. The disadvantage of EMB compared to EHB is the higher cost, since an EMB is required for each wheel; however, the advantage of EMB is that it can be centrally controlled very simply, since a central driving dynamics control system FDS with ABS and ESP functions can be developed independently of the brake manufacturer and integrated into the domain and the application of electromechanical brakes is significantly simpler than electrohydraulic brakes. This applies in particular to standard ABS systems with open brake circuits, where very complex and adaptively learned pressure estimation models are required. The increasing spread of EMB is therefore not primarily driven by unit costs, but by lower application costs and simpler integration.

[0007] exist Figure 1a A typical vehicle architecture with an electric drive for SAE Level 3-4 is shown in Figure 1a This is known here: https: / / www.lsp-ias.com / our-world / chassis-control). In this case, for example, an electric friction brake system with a brake booster and an ESP unit is used according to WO 2019 / 214833 A1.

[0008] Furthermore, it is known from WO 2019 / 002475 A1 that the brake can be controlled as a pressure regulator centrally controlled via a central computer, i.e. a domain, so that the braking torque is determined in the central computer and the electrohydraulic brake is used only as a pressure regulator for implementing the desired braking torque or desired pressure.

[0009] Furthermore, WO 2020 / 165255 A1 discloses an electrohydraulic brake system in which, in the event of a failure or partial failure of the pressure supply device, braking is performed or supported via an electric traction motor and / or an electric parking brake.

[0010] Furthermore, a so-called combined brake is known from WO 2019 / 215278 A2, in which an electrohydraulic brake (EHB) is used at the front axle and an electromechanical brake (EMB) or a hydraulically assisted electromechanical brake (H-EMB) is used at the rear axle.

[0011] WO 2020 / 128081 is directed to an electric axle module in which a pressure regulator supplies pressure to hydraulic consumers, in particular hydraulic wheel brakes.

[0012] WO 2018 / 215397 A1 is devoted to the concept of a central control of an electric motor and an electrohydraulic brake, wherein the focus is on the shortest time to reach the locking pressure (English: time-to-lock, abbreviated: TTL). In addition, the function of the brake is only introduced via the electric traction motor by using a vehicle model depending on the driving situation.

[0013] WO 2021 / 037658 A1 provides a further concept for centrally controlling an electric traction motor and an electrohydraulic brake, namely centrally controlling the distribution of the electric braking force during simultaneous recuperation via an electric motor.

[0014] In the prior art, the overall optimization of driving dynamics control and cost reduction by using the synergistic effect of EMB or EHB in combination with an electric traction motor has not been fully investigated at all, because the brake-by-wire brake and the braking via the electric traction motor are considered as independent units, and the braking via the electric traction motor is limited to a deceleration of about 0.3 g for safety and liability reasons, in particular to avoid safety-critical driving situations. In addition, if the required regenerative energy for the energy sink is generated via the electric traction motor, the battery is technically limited in terms of energy absorption, in particular at a full battery state of charge (SOC). The synergistic effect potential of the joint use between drive motor and brake is very high, because electric drive motors are becoming more powerful and dynamic in the development of electric vehicles due to high-voltage technology (in particular 400 V or 800 V) and thus have the potential to contribute decisively to shortening the braking distance. In particular, the combined use of electric traction motors offers a very large potential for new innovative concepts in highly dynamic brake control processes, in particular ABS control.

[0015] Furthermore, the potential for improving the functionality by using different units simultaneously during acceleration and braking and for streamlining and reducing costs has not yet been investigated.

[0016] Furthermore, the application effort of brakes is currently characterized by very extensive application work, wherein in brake systems according to the prior art (EP 2 536 607 B1, EP 3 036 136 B1) with ABS control with pre-pressure control via a plunger and pressure build-up via an inlet valve and with time-controlled pressure release via an outlet valve, complex pressure models that must be adapted to each vehicle are required. Therefore, a large number of application engineers have been working on vehicle applications for all driving situations and friction coefficient conditions for many years. Summary of the invention

[0017] The object of the present invention is to provide a driving dynamics system (FDS) with a central control via a driving dynamics domain or a central computer and with a wheel module or a vehicle axle module with a plurality of brake units (electric traction motor, electrohydraulic pressure regulator (EHB) and / or electromechanical brake actuator (EMB)), wherein the synergy between the individual brake modules is used to the maximum extent for achieving the braking purpose. In this case, the overall cost, weight and thermal load of the components of the brake system should be minimized. At the same time, the braking distance should be minimized and driving stability should be ensured.

[0018] The wheel modules or axle modules should therefore preferably be controlled so that the corresponding wheels or vehicle axles only carry out the desired braking torque and the distribution of the braking torque to the wheels or axles is calculated in a central computer, where the core functions are also implemented, namely the anti-lock braking system ABS, anti-slip control ASR, electronic stability program / electronic stability control ESP / ESC, electric brake force distribution EBV and recuperation brake management. The control electronics of the wheel modules or axle modules also have the purpose of distributing the desired braking torque to the various brake units of the wheels or vehicle axles.

[0019] Furthermore, a method for controlling the vehicle in a highly dynamic braking operation (AEB emergency brake function and in particular subsequent ABS control operation) is to be provided for a vehicle with a corresponding driving dynamics system (FDS), which method is optimized with regard to the braking distance and by which the controllability in the driving situation (ABS operation on snow or ice) is optimized. Furthermore, the brake module is to be designed so that rapid application is possible and in particular can be automated.

[0020] Furthermore, the brake module is advantageously conceived so that interruptions in the control operation are avoided or prevented by re-delivering the hydraulic volume, as learned from EP 2 580 095 B1 and implemented on the market in two integrated brake systems (DE 10 2018 212 905 A1, DE 10 2019 204 016 A1), or by avoiding or preventing dead times in multi-path control methods, or by compensating for them by control interventions via the electric traction motor.

[0021] Furthermore, the brake module is advantageously designed such that a diagnosable valve device, in particular a normally open wheel valve (in a subsequent Figure 6a Indicated as MV 2k,1 MK 2k,2 , MV 2k,3 , MV 2k,4 ) and / or circuit isolation valves (in subsequent Figure 6b Indicated as MV 2k,TV), the wheel valves and / or circuit isolating valves are designed for bidirectional volume flow, that is to say, not only when pressure is built up but also when pressure is released, the wheel valves and / or circuit isolating valves are able to isolate the corresponding consumer by closing the valve device when the consumer leaks and continue to operate the system with one less consumer.

[0022] In the prior art (EP 3 036 136 B1), for example, a check valve is provided in parallel with the wheel inlet valve (represented as inlet valve 88 and check valve 92 in FIG. 1 of EP 3 036 136 B1), which is required so that the pressure in the wheel brake can be safely released in any case, especially when the ECU or the energy supply device fails.

[0023] The new design with a normally open valve device has a decisive advantage over this, and a failure of the wheel circuit can be clearly diagnosed, because there is no uncertainty as to whether the leakage is caused by the switching valve or the non-return valve. If a valve leakage or a failure of the hydraulic line to the wheel brake or multiple wheel brakes is diagnosed, for example by a method as described in WO 2018 / 011021 A1, the hydraulic circuit can be safely isolated by closing the valve and the braking system can continue to operate with only one less consumer. This has advantages over braking systems with typically two brake circuits and four wheel brakes (in the prior art, represented as black and white brake circuits (II) or diagonal brake circuits (X)), where two wheel brakes must be directly deactivated in the event of a fault. The advantages of the new valve device are considerable: namely, in the event of a fault, the deceleration that can be achieved with three wheel circuits instead of two wheel circuits is significantly higher, and it is also possible to maintain yaw torque intervention and steering intervention for ESP with three wheel circuits without performance loss. Furthermore, even in the event of a fault, a braking torque control using the four wheel brakes is possible if an electric drive motor is available for driving and braking the failed wheel and is integrated into the control.

[0024] Furthermore, the braking system should be designed in such a way that simple application of core functions is possible during development via central control, in particular due to the high computing power of a central computer or a domain computer, leading to automated application of the functions, and in particular also during vehicle operation via learning algorithms or artificial intelligence (AI) not only before the vehicle is put into operation for the first time, but also subsequently during operation for fault-free normal operation and for adaptation in the event of a fault.

[0025] In the AI ​​concept, a powerful central computer with sufficient performance can take over the tasks of the application engineer, which is not possible with a microcontroller according to the prior art, as is provided in known control and control units for brake systems, due to very limited power and limited memory. The central computer therefore receives the measurement data during vehicle operation, evaluates them and applies various functions, in particular the safety-critical functions ABS, ESP and AEB, during vehicle operation or when the vehicle is stationary, when the vehicle is not moving and the adaptation is therefore not time-critical.

[0026] Therefore, the adaptation is carried out in particular after the vehicle has been put into operation, when the vehicle is stationary. The preferred embodiment as a closed hydraulic system, in particular with pressure build-up and pressure release by means of a pressure supply unit via a bidirectional valve, has the great advantage that nonlinear relationships can be described by suitable sensors via characteristic diagrams (e.g., pressure-volume characteristic curves when the wheel brakes are heated up, the relationship between motor current and brake pressure, the relationship between brake pressure and / or deceleration). Furthermore, during operation, the characteristic diagrams can be adapted by detecting environmental influences, such as the air in the system or the heating of the wheel brakes.

[0027] Automatic application of the electrohydraulic brake system is also possible if non-linear relationships are depicted in the mathematical function or the characteristic diagram.

[0028] If the AI ​​concept is implemented consistently in the case of hydraulic brake systems (EHB), the advantages of a simply adjustable or controllable electromechanical brake (EMB) disappear and the advantages of the lower production costs of hydraulic brake systems come into play, since the disadvantages in the application costs largely disappear.

[0029] Furthermore, different solutions should be investigated depending on the electric drive architecture and the level of automated driving. Therefore, solutions are presented below for different architectures of the arrangement of the electric traction motor, which are Figure 1b It shows:

[0030] a) Electric traction motors TM1, TM2 at the rear axle HA or the front axle VA;

[0031] b) Electric traction motor TM1 at the rear axle HA and electric traction motor at the front axle VA

[0032] TM3;

[0033] c) two electric traction motors TM1 , TM2 at the rear axle HA for wheel-individualized torque regulation of the two wheels R1 , R2 ; and

[0034] d) Two electric traction motors TM1 , TM2 at the rear axle HA and an electric traction motor TM3 at the front axle VA.

[0035] Variants a) to d) can be combined as desired, with the most effective solutions b) and c) being important for further embodiments according to the invention.

[0036] In addition to the electric drive module, the following configurations of brake units should be investigated, which are Figure 2 c shows:

[0037] a) a central electrohydraulic brake (EHB-Z) with wheel-individualized braking torque control capability via solenoid valves for the four wheel brakes (R1, R2, R3, R4);

[0038] b) an axle module having an electrohydraulic brake (EHB-VA) with wheel-individualized braking torque control capability for two wheels (R1, R2) of the front axle (VA), optionally in combination with a hydraulic line to two wheel brakes (R3, R4) of the rear axle (HA) (see, for example, the detailed description below) Figure 6b and 6c );

[0039] c) an axle module having two wheels (R1,

[0040] R2; R3, R4) with wheel-individualized braking torque control via solenoid valves (EHB1, EHB2); and

[0041] d) A wheel module having an electromechanical brake (EMB1-EMB4) for each wheel (R1, R2, R3, R4) of the vehicle.

[0042] Furthermore, the different requirements of SAE levels 2-5 of automated driving should be taken into account in the design of the embodiments. Solutions are differentiated according to whether only a fail-safe solution is required for SAE level 2 and a fail-operable solution is required for SAE levels 3-5.

[0043] - The following priorities apply to brake systems:

[0044]

[0045] The following main requirements are defined based on the above-mentioned priorities, the duration and speed of autonomous driving operation (SAE Level 3-4), the time delay when the driver intervenes, and the assumption of responsibility by the vehicle manufacturer.

[0046]

[0047]

[0048] The object of the invention is achieved by a driving dynamics system FDS according to the independent claims, a vehicle having a driving dynamics system according to the independent claims and a method for operating a driving dynamics system according to the independent claims. Advantageous embodiments and developments of the invention are described in the dependent claims.

[0049] The driving dynamics system for a vehicle comprises, in particular, at least one wheel brake for dissipative braking of one wheel of the vehicle and at least one brake unit, which is associated with the at least one wheel brake and is configured to generate a dissipative braking torque by means of the at least one wheel brake. The driving dynamics system also comprises at least one electric traction motor, which can be controlled to generate a regenerative braking torque for at least one wheel or axle of the vehicle. The driving dynamics system also comprises a central control unit, which is configured to control at least one brake unit and at least one electric traction motor for a braking function that is combined with one another, so that a combined braking torque can be generated by means of at least one brake unit and at least one electric traction motor. In this case, the braking function is a control situation in which a basic braking torque and a regulated additional braking torque are controlled and / or regulated simultaneously. In this case, the basic braking torque is optionally generated by at least one brake unit and the regulated additional braking torque is generated by at least one electric traction motor; or the basic braking torque is generated by at least one electric traction motor and the regulated additional braking torque is generated by at least one brake unit; or at least one brake unit and at least one electric traction motor respectively jointly generate the basic braking torque and the regulated additional braking torque.

[0050] In one embodiment of the present invention, the braking function is selected from at least one of the following functions, preferably more than one:

[0051] Automatic emergency braking (AEB), in particular by means of EBV control, in particular with EBV control at the rear axle and the front axle of the vehicle, wherein the total braking torque is distributed to the rear axle and the front axle;

[0052] an anti-lock braking system (ABS), in particular with basic braking torque support via at least one traction motor (TM1, TM2, TM3, TM4);

[0053] -Electronic Stability Program (ESP);

[0054] - Electronic Brake-force Distribution (EBV);

[0055] - Anti-slip Regulation (ASR);

[0056] - Distance adjustment (Automatic Cruise Control, ACC);

[0057] - Recycling management, in particular for the recycling of individual axles or wheels;

[0058] - Foundation brakes with thermal management;

[0059] - yaw moment control in the event of wheel brake failure; and / or

[0060] -Yaw moment intervention control for steering support.

[0061] In particular, the central control unit may have a central computer, wherein the central computer preferably has redundant microcontrollers μC1 , μC2 , μC3 and / or a large memory, in particular in the order of magnitude of gigabytes.

[0062] In a further embodiment of the vehicle dynamics system, the brake unit comprises an electric drive and is designed as an electrohydraulic brake unit or as an electromechanical brake unit.

[0063] In one refinement, the brake unit is designed as an electrohydraulic brake unit with an electrically operated pressure supply unit, wherein a valve device is provided between the pressure supply unit and at least one wheel brake or a plurality of wheel brakes of the vehicle axle, wherein the valve device comprises a normally open wheel valve and / or a circuit isolation valve, wherein in the event of leakage of at least one wheel brake, the valve device is configured to isolate the wheel brake in question by closing the valve device, and the central control unit is configured to control at least one brake unit and / or at least one electric traction motor such that a braking torque is regulated at other wheels of the vehicle, in particular at at least three wheels. In this case, the wheel brakes of the axles of the vehicle, in particular the wheel brakes of the front axle, can be isolated, in particular, by means of the valve device.

[0064] In one development, the central control unit is coupled to at least one brake unit control unit of the brake unit.

[0065] In a further embodiment, the central control unit is configured to transmit the desired signal to a motor controller of at least one traction motor and to a brake unit controller of at least one brake unit during a braking function.

[0066] In one embodiment, the central control unit is further configured to actuate the at least one electric traction motor for regenerative braking of the vehicle during normal operation when the vehicle speed exceeds 80 km / h, wherein during regenerative braking, electronic brake force distribution (EBV function) is simultaneously implemented at the front axle and the rear axle of the vehicle, in particular 20% to 40% of the total braking torque acting on the rear axle of the vehicle and 60% to 80% of the total torque acting on the front axle of the vehicle.

[0067] In a refinement, the wheel brakes of the wheels of the vehicle are associated with their own brake units, wherein the brake units are particularly electromechanically configured. Here, in particular for each wheel in the two wheels, the brake units associated with the wheel brakes and the electric traction motor are integrated into the wheel module.

[0068] In one configuration, the wheel brakes of two wheels of the vehicle's axle are associated with a common brake unit. Here, the brake unit is particularly electrohydraulic, wherein in particular the two wheels of the rear axle are associated with a first brake unit and the two wheels of the front axle are associated with a second brake unit.

[0069] In this case, a central brake unit is associated with the wheel brakes of the four wheels of the vehicle, wherein the central brake unit is in particular of electrohydraulic design.

[0070] In one embodiment, the wheel brakes of the two wheels of a first axle of the vehicle, in particular the front axle, are associated with a common brake unit. In this case, the brake unit is in particular of electrohydraulic design. In particular, a wheel-individualized dissipated braking torque can be set in the wheel brakes of the first axle, in particular by means of a solenoid valve in the hydraulic circuit between the brake unit and the wheel brake. In particular, the brake unit can also be connected via a hydraulic circuit to the wheel brakes of the two wheels of a second axle, in particular the rear axle. In this case, in particular, a common, non-wheel-individualized dissipated braking torque can be set in the wheel brakes of the second axle.

[0071] In one embodiment, a first electric traction motor is associated with a first pair of two wheels of a first axle, in particular a rear axle, of the vehicle, and a second electric traction motor is associated with a second pair of wheels of a second axle, in particular a front axle, of the vehicle.

[0072] In one embodiment, a dedicated electric traction motor is each assigned to the first and second wheels of a first axle, in particular a rear axle, of the vehicle.

[0073] In a further development, the first and second wheels are each further associated with their own brake unit, wherein the respective brake unit is in particular of electromechanical design. In this case, in particular the electric traction motor and the respectively associated brake unit respectively associated with the first and second wheels are integrated into a wheel module respectively associated with the first or second wheel.

[0074] In another embodiment, a third electric traction motor is also associated with the third and fourth wheels of the second axle of the vehicle, in particular the front axle. In this case, in particular a common brake unit is associated with the third and fourth wheels. In this case, the common brake unit is in particular electrohydraulic. In this case, in particular the third electric traction motor and the common brake unit are integrated into an axle module associated with the second axle; or in particular a central brake module is provided, which is in particular electrohydraulic, wherein wheel-individualized braking torques can be generated for the first and second wheels and a common braking torque can be generated for the third and fourth wheels by means of the central brake module.

[0075] In one embodiment, the central control unit is configured to distribute the basic braking torque and the regulated additional braking torque to at least one brake unit and at least one electric traction motor as a function of the vehicle deceleration and / or as a function of the friction coefficient of the road surface. In this case, the electric brake unit and / or the at least one electric traction motor generate the regulated additional braking torque, especially at lower decelerations and / or lower friction coefficients, such as during ABS control on snow or ice or during deceleration in ABS braking operation. In this case, the electrohydraulic brake unit generates the regulated additional braking torque, especially at higher decelerations and / or higher friction coefficients, such as during braking on asphalt. In this case, in particular at medium decelerations and / or medium friction coefficients, one brake unit or traction motor generates the basic braking torque as a constant braking torque, and the other brake unit or traction motor generates the regulated additional braking torque.

[0076] In an improvement, the central control unit is configured to implement EBV regulation during automatic emergency braking, taking into account the braking torque gradients of at least one brake unit and of at least one electric traction motor so that a maximum braking torque is reached simultaneously at the front axle of the vehicle and at the rear axle of the vehicle, in particular the maximum braking torque before the wheels lock.

[0077] In one development, during regenerative braking, in particular when the battery of the vehicle is fully charged, at least one of the following strategies is used:

[0078] - Feeds regenerative energy back into the battery up to the limit of power consumption;

[0079] - field-oriented regulation (Id / Iq current regulation) of the electric traction motor so that the energy in the motor is dissipated internally;

[0080] - dissipating the energy obtained by the electric traction motor in generator mode, supplying the obtained energy to electrical consumers of the vehicle and / or warming up a fluid reservoir for use with a heat pump for cooling or heating; and / or

[0081] - Use of preferably electrical intermediate stores designed for pulsed power, such as supercapacitors or flywheel stores.

[0082] In one refinement, at least one electric traction motor is operated with an inverter, which is used to switch the winding of the at least one electric traction motor into a series or parallel connection of three branches of the field coil of the brushless motor. In particular, the inverter can be used to achieve a four-quadrant operation, i.e., quadrant 1 with positive speed and positive torque of the motor, quadrant 2 with positive speed and negative torque of the motor, quadrant 3 with negative speed and positive torque of the motor, and quadrant 4 with negative speed and negative torque of the motor.

[0083] In one embodiment, the central control unit is configured to carry out brake control according to a characteristic map, wherein the characteristic map describes in particular a pressure-volume characteristic when the wheel brakes are heated up, a relationship between motor current and brake pressure and / or a relationship between brake pressure and / or deceleration.

[0084] In another embodiment, the central control unit is configured to acquire sensor data during vehicle operation, in particular in a state after the vehicle is put into operation for the first time, for example, during driving operation or in a stationary state before or after driving operation, and to adapt the control of the brake function based on the acquired sensor data by means of artificial intelligence methods, in particular machine learning or neural networks. In this case, the artificial intelligence method can be implemented in particular by means of a computer of the central control unit. In particular, the adaptation is implemented in a safe state of the vehicle, in particular in a stationary state of the vehicle. In this case, a characteristic curve group is determined in particular based on the acquired sensor data, which characteristic curve group, for example, depicts a pressure-volume characteristic curve when the wheel brake is heated up, a relationship between the motor current and the brake pressure and / or a relationship between the brake pressure and / or the deceleration. In this case, in particular, if a deviation from the current characteristic curve group is detected, for example due to environmental influences, air in the system or due to heating of the wheel brake, the characteristic curve group can be adapted based on the sensor data and the artificial intelligence method.

[0085] Another driving dynamics system for a vehicle comprises: at least one electric traction motor, which can be controlled to generate a regenerative braking torque for at least one wheel or axle of the vehicle; and a central control unit, which is configured to control the at least one electric traction motor for a braking function. The central control unit is configured to control the at least one electric traction motor for a braking function when braking on a road surface with a low friction coefficient, in particular on snow, ice and / or wet road surfaces, at a low to moderate speed, in particular less than 0.5 m / s 2The central control unit is hereby configured in particular to implement the braking function by means of at least one traction motor of at least one axle of the vehicle, in particular by means of two traction motors of the rear axle of the vehicle.

[0086] A vehicle according to the invention comprises a driving dynamics system according to the above description or according to a dependent claim.

[0087] In a method for operating a vehicle dynamics system, wherein the vehicle dynamics system has at least one brake unit for generating a dissipative braking torque and at least one electric traction motor for generating a regenerative braking torque for at least one wheel or axle of a vehicle, and a central control unit for controlling the at least one brake unit and the at least one electric traction motor for a braking function, a combined braking torque is generated by means of the at least one brake unit and the at least one electric traction motor. In this case, the braking function is a control situation in which a basic braking torque and a regulated additional braking torque are controlled and / or regulated simultaneously. In this case, the at least one brake unit is optionally controlled to generate a basic braking torque and the at least one electric traction motor is controlled to generate a regulated additional braking torque; or the at least one electric traction motor is controlled to generate a basic braking torque and the at least one brake unit is controlled to generate a regulated additional braking torque; or the at least one brake unit and the at least one electric traction motor are controlled to jointly generate a basic braking torque and a regulated additional braking torque, respectively.

[0088] In particular, at least one electric traction motor for driving and braking an axle or a wheel of a vehicle has a slave controller at one or more axles or wheels of the vehicle.

[0089] In particular, the at least one brake unit or brake system is designed for a plurality of wheel brakes, a plurality of electrohydraulic brake modules or a plurality of electromechanical brake modules.

[0090] In this case, for example, a central vehicle model may be provided for control, with the aid of which the braking request to the wheel modules or axle modules may be calculated during a braking process taking into account the friction coefficient of the road surface, the vehicle speed and the weight distribution.

[0091] Furthermore, a braking control model and a characteristic curve family for synchronous braking torque control of at least one traction motor and a brake unit, in particular an EHB or an EMB, can be provided in the following sense: either at least one electric traction motor or a brake unit, in particular an EHB or an EMB, provides a basic braking torque, while dynamic braking torque control is performed jointly by at least one electric traction motor and a brake unit, in particular an EHB or an EMB, in particular by means of a regulated additional braking torque generated thereby.

[0092] Furthermore, sensor data of sensors can be used, wherein the sensor data are relevant for the realized core functions and are read into the central control unit. For example, sensor data of the following sensors can be provided: wheel speed sensors for the ABS function, yaw moment sensors for the ESP function, acceleration sensors and / or weight sensors for the EBV function and the balancing of the functional relationship between brake pressure / brake torque and deceleration of the vehicle, in particular in relation to the temperature of the brake disk(s) and / or sensors for the electric recuperation strategy or the emergency brake function (AEB).

[0093] For example, a central driving dynamics system can be used to optimize the use of at least one brake unit in different driving situations with regard to recuperation and maximization of braking power or brake control power. This is done in particular as a function of the braking situation, such as comfort braking or emergency braking, and the road surface, such as braking on asphalt, on snow or on ice, in the case of so-called friction coefficient jumps (μ-Sprung) or friction coefficient differences (μ-Split), and the availability of the brake unit. In particular, the costs of the brake caliper can be reduced by intelligent control via the driving dynamics system, in particular by minimizing and reducing the thermal load on the friction brake and / or selecting the appropriate type of friction brake used, such as a drum brake or a disk brake.

[0094] Thus, already in the first "architecture I", the hydraulic brake system (EHB-Z) for the wheels of the front and rear axles or the hydraulic brake system (EHB-VA) only for the front axle can be controlled via the central control unit as a brake unit together with at least one electric traction motor. In architecture I, a controller (M-ECU) is provided for each of the brake units EHB-Z or EHB-VA and the at least one electric traction motor of the respective axle. BM 、S-ECU TM,HA 、S-ECU TM,VA ), the controller has an interface to the central control unit. Central control unit M-ECU 域 Synchronously provide the desired signal to the above-mentioned controller (M-ECU BM 、S-ECU TM,HA 、S-ECU TM,VA ), wherein the desired signal is in particular a desired braking torque or includes the desired braking torque.

[0095] The described architecture can already open up a large potential for SAE level 2 brake systems with fail-safe operation without any changes to the installed brake system. Such a brake system can be, for example, a single-box brake system commonly found on the market, as described, for example, in DE 10 2018 212 905 A1, DE 10 2019 204 016 A1 or DE 10 2019 122 169 A1. For this purpose, a mechanical or hydraulic design of the brake system is not required, but only an extension via interfaces, such as a wheel-individual desired pressure interface or a wheel-individual desired torque interface. This is achieved by intelligent control of the brake units and the installed electric traction motors, which are integrated into a central control unit (domain) and at one or two vehicle axles or at two wheels of a vehicle axle.

[0096] Advantageously, as an alternative to the conventional brake system mentioned above, the brake unit (EHB) is further optimized so that the brake unit (EHB) is designed only as a wheel-individualized pressure regulator with a wheel control valve. Each of the hydraulically activated wheel brakes forms a separate wheel circuit and can be activated preferably by closing the preferably normally open wheel valve MV 2k To isolate. In addition, an EHB pressure regulator (EHB-1, EHB-VA) with a control valve only for the front axle and / or a pressure regulator (EHB-2) and / or a pressure regulator (EHB-Z) with a control valve for the rear axle can be provided as a brake unit, and additionally a brake circuit for the two wheels of the rear axle. In the above-mentioned solutions EHB-1 and EHB-2, the "architecture II" explained in the following paragraphs and figures is used.

[0097] In the embodiment for SAE level 4, the driver's request is no longer conventionally detected using an operating unit for detecting the driver's request, but rather using a piston-cylinder unit with preferably a piston and a hydraulic pressure chamber and a hydraulic connection to the brake circuit or via an electric pedal. The driver's request signal is redundantly read into the M-ECU 域 In SAE level 5, a pedal is no longer required. The modular design with an electric pedal has decisive advantages over the prior art, and can cover SAE levels 4 and 5 modularly and, by eliminating the hydraulic connection between the actuating unit and the pressure regulator, allows a particularly high degree of flexibility in the installation of the pressure regulator in the vehicle. In addition, noise sources are avoided, since the hydraulic pressure modulation noise is generated away from the front panel, so that no structure-borne sound is transmitted to the passenger compartment. This embodiment of the electrohydraulic brake system is Figures 6a to 6d Described in detail in.

[0098] The different specific embodiments of the brake unit (EHB) and architectures I to II explained above can therefore be implemented by means of a central vehicle model, with the aid of which functions (a) to (g) are implemented.

[0099] In the first advantageous function (a) foundation brake function, Minimizes heating of friction brakes , in that at least one electric motor is primarily used for braking. If a braking device is designed according to the prior art with a covering strategy (see for example Figure 1b ), the maximum pressure during the AMS fading test is used as the basis for the design dimensioning (see "Bremsenhandbuch (Brake Handbook)", 5th edition, Chapter 6.3.2, Figure 6.10). That is, for the AMS test, 10 consecutive brakings starting at 100 km / h are simulated. The wheel brakes of the front axle therefore heat up to 600° C. and the wheel brakes of the rear axle to approximately 500° C. The pedal force in a standard vacuum brake booster then increases by approximately 80%, that is, the brake system must be designed for a pressure that is 80% higher than the normal locking pressure for fading situations. With a corresponding safety reserve, the brake system is therefore typically designed for a maximum pressure of approximately 200 bar to 220 bar. Typical masking strategies do not have regenerative braking at higher speeds above 60 km / h ("Brake Handbook", Chapter 19.3.2, Figure 19.12); the potential of the braking power of the electric motor is therefore not fully utilized. The limits of regenerative braking in the speed range above 60 km / h are caused on the one hand by the limits of the volume absorption during the cover, for example by the volume absorption of the storage chamber of the ESP unit in a two-tank brake system with an electric continuous brake booster. On the other hand, the liability basis of the brake manufacturer and the extended legislation with respect to the regenerative braking operation are mentioned. In addition, the limits can be caused by the fact that the energy absorption capacity of the battery is limited, especially in the fully charged state.

[0100] In the case of a central FDS control, the potential of regenerative braking can be fully utilized. In addition, the heating of the friction brake and thus also the attenuation effect can be significantly reduced, since the braking energy no longer causes a significant heating of the friction brake. For example, at least one electric traction motor can be operated with an inverter, with which a four-quadrant operation is possible (quadrant 1: positive speed, positive torque; quadrant 2: positive motor speed, negative motor torque; quadrant 3: negative motor speed, positive motor torque; quadrant 4: negative motor speed, negative motor torque). Thus, at the rear axle of a mid-range vehicle (see the BMW i3 vehicle with a maximum braking torque of 2000 Nm at the rear wheels / 3000 Nm at the front wheels), an electric traction motor with an exemplary drive power of 130 kW with a torque of 250 Nm can also brake in the second quadrant with approximately the same torque and the same power. The generator braking torque of the electric traction motor is slightly higher here than the driving braking torque of the electric traction motor, since the losses in the motor and the transmission also have a braking effect, while they reduce the loss of drive torque during acceleration. Thus, with this design, approximately 60% to 70% of the braking energy can already be obtained at the rear axle by regenerative braking at a speed of 100 km / h. If such a motor is also installed at the front axle, a deceleration of approximately 50% can also be achieved at the front axle. During braking via the electric traction motor, one or more energy management strategies are followed, wherein the braking via the electric traction motor is limited in practice only via the torque limit in four-quadrant operation of the inverter by efficient selection or combination of strategies.

[0101] The following four basic strategies are available for energy management:

[0102] (1) Feedback into the battery up to the limit of the power consumption: This depends, among other things, on the energy absorption capacity of the battery, in particular on the current state of charge (SOC) of the battery.

[0103] (2) Field-oriented control (Id / Iq current control) of the electric motor, so that the energy in the electric traction motor is dissipated internally: The internal energy dissipation is limited by the resistance and eddy current losses of the field winding of the stator of the electric traction motor and the cooling possibility of the motor. Since water or oil cooling is provided in the electric traction motor and the temperature rise during the pulse load during the braking process, which is generally completed within 5-10 seconds during full braking, is also damped by the large thermal mass of the electric motor, the absorption of energy by the electric motor in pulse operation is relatively uncritical and can usually be fully utilized.

[0104] Furthermore, the cooling circuit of the electric traction motor can be led into a water tank which in turn is used by means of a heat pump for particularly efficient cooling and heating of the vehicle's interior. This makes it possible to use the energy "dissipated" in the traction motor, in particular with a heat pump efficiency of more than 300%.

[0105] (3) As a third option, the energy generated by the electric traction motor in generator mode can be used via wear-free eddy current brakes, such as those known from motor test benches, or another medium (e.g. water) can be heated similarly to a water heater. The heat generated can also advantageously be used via a heat exchanger for particularly efficient cooling or heating of the vehicle. Preferably, the energy of the electric traction motor or motors is directed to a heat sink.

[0106] (4) As a fourth option, an electrical intermediate storage device designed for pulsed power, such as a supercapacitor or a flywheel accumulator, can be provided. Supercapacitors or flywheel accumulators are particularly well suited for pulsed power and can absorb significantly higher peak powers than batteries. The energy temporarily stored in the supercapacitor or flywheel accumulator can be used after a braking process when accelerating the vehicle or can be used elsewhere in the vehicle.

[0107] By means of recuperation brake management with energy management, the heating of the friction brakes in the AMS test can be reduced by more than 50%, in particular even by up to 70% to 80%. This effect can be advantageously used to simplify the friction brakes at the front axle and to advantageously use cost-effective drum brakes with a simultaneously low weight at the rear axle. Alternatively, this effect can be used to design hydraulic brakes for significantly lower maximum brake pressures, for example 120 bar to 140 bar instead of 200 bar to 220 bar, which has a favorable effect on the costs of the brake system, since the pressure supply can be equipped with a smaller electric motor. In addition, the hydraulic volume of the pressure supply unit can be reduced.

[0108] Furthermore, the dynamics of automatic emergency braking (AEB) can be further improved by a suitable design of the interface between the driving dynamics system and the braking system in the second advantageous function (b) with an input for adjusting the electronic brake force distribution (EBV function), which has a significant effect on the braking distance, particularly at high vehicle speeds. If braking is carried out via an electric motor, the driving dynamics system must be ensured to meet legal requirements and vehicle safety, and driving stability (see above - priority 2) and steerability (see above table - priority 3) must be achieved. This means, for example, that the rear axle must not lock before the front axle and that the ABS must be activated when the wheels, especially the wheels of the front axle, lock. Therefore, the interface between the driving dynamics system and the braking system must be designed and the EBV function preferably controlled in such a way that the maximum braking torque (wheel lock limit) is reached at the front and rear axles almost simultaneously. Thus, as described below with reference to Figure 4It is explained that the time from the start of braking to the maximum deceleration (TTL time) can be reduced from 140 ms to 90 ms even in the case of an electric traction motor with an average power of 130 kW at the front and rear axles of a mid-range vehicle. At speeds above 100 km / h, this can lead to a reduction in the braking distance of several meters. If a reduction in the TTL time is not possible, for example due to chassis restrictions, the braking effect by the electric motor can also be used as an alternative, in order to implement the brake system more cost-effectively and in a smaller size. That is to say, the pressure supply of the brake unit can be driven by a motor with a lower torque and / or by a less powerful motor, if necessary also by a cost-effective commutator motor.

[0109] In a third advantageous function (c), axle-type recuperation can be realized via the electric motor. Here, too, the driving dynamics system is limited to accessing the solenoid valve of the brake unit (EHB) or a suitable interface to the brake unit (EHB) in order to intervene in the ABS operating state in critical fault situations. In the interaction between the brake unit (EHB) and the electric traction motor controlled by the driving dynamics system, the pressure release and pressure buildup via the inlet valve or isolating valve of the brake circuit to the front axle must be correspondingly adjusted for the cover. This can be done, for example, via PMW control of the inlet valve in the pressure buildup and, alternatively, via the MUX method via the inlet valve or isolating valve or via pressure release by means of an outlet valve.

[0110] The solution in the EHB-Z and EHB-VA brake units is simpler and significantly more flexible, as shown below: Figures 6a to 6d The description is simpler and significantly more flexible, in particular, if the wheel inlet valve is designed as a normally open solenoid valve MV designed for bidirectional volume flow. 2k (also additionally denoted as inlet / outlet valve) in order to be able to maintain pressure due to the lack of a non-return valve in the following situations: the pressure supply has a lower pressure level than the wheel brake and the hydraulic braking torque is to be maintained constantly in the recuperation strategy. Figure 9a In the implementation of EHB or Figure 6a-6d In the variant according to , there is no outlet valve or only some of the wheel brakes are provided, the pressure relief takes place only via the inlet / outlet valve, and in the variant according to Figures 6a to 6d as well as Figure 9b In the embodiment according to , there is a degree of freedom to release the braking torque via the inlet / outlet valve or via the outlet valve. This is advantageous in achieving very dynamic braking torque interventions. Figure 6b In the embodiment of the invention, the axle-specific recovery strategy is also less impaired, since the pressure release is selectively carried out via the inlet / outlet valve MV 2k,1-4Or outlet valves AV1-AV4. In the recuperation strategy via the driving dynamics system, the braking torque curve can be synchronized by the electric traction motor and the brake unit (EHB) to maximize the recuperation. If the recuperation via the electric traction motor is limited, for example in the fully charged state of the battery, the kinetic energy is dissipated via the brake unit (EHB); if the battery allows feeding, the recuperation is mainly via the electric traction motor. Therefore, the freedom of wheel individualization can also be easily realized with axle-type recuperation with X-braking force distribution.

[0111] In the case of an axle pressure regulator (EHB-1, EHB-2), preferably there is Figure 9a and 9b In the embodiment of the construction, the recovery strategy is very simple and does not require valve confirmation, because the braking torque build-up and braking torque release can be performed very accurately using the known PPC pressure regulation or pressure control.

[0112] In a fourth advantageous function (d), at least one electric traction motor is capable of generating a basic braking torque in controlled operation. This can be achieved by using modern high-power and high-torque traction motors (>200 Nm, <100 kW) and operating them at a high operating voltage (400 V, in particular 700 V to 900 V). Such a traction motor can be operated with high dynamic braking torque variations (typical value: 15000 Nm / s, 30000 Nm / s achievable), it can operate in four-quadrant operation and it is very dynamic in braking torque buildup and braking torque release. At low desired braking torques, the traction motor is more dynamic than a hydraulic brake unit (EHB). Depending on which torque is available over the total speed range (in Figure 3 In the case of a braking system with a maximum torque of 1000 Nm up to the maximum vehicle speed, the maximum pressure of the braking unit (EHB) can be reduced by the maximum torque. Since the new ASR control with the aid of electric traction motors has become possible (see ATZ 2 / 2014: "Regelalgorithmen fürRekuperation und Traktion bei Elektrofahrzeugen (Control algorithm for recuperation and traction in electric vehicles)"), high pressures are no longer required for ASR control compared to the earlier prior art, so that the maximum pressure of the braking unit (EHB) is determined by normal braking operation.

[0113] In the fifth advantageous function (e), at least one electric traction motor can be used to support the failure of the brake unit (EHB). Newer single-box brake systems, such as those shown in DE 10 2018 212 905 A1, are designed so that in the event of a failure of the pressure supply mechanism, the driver's foot force can only reach 0.3 m / s. 2The deceleration rate satisfies the requirement of 0.244 m / s 2 The minimum deceleration of the vehicle meets the ECE-13-H regulation requirements and also meets the regional requirements in China. If the brake unit (EHB) is connected to the driving dynamics system, the braking force in the event of a fault can be increased to 0.58 m / s by using the braking force of the electric drive motor, as proposed in WO 2020 / 165255 A1, for example. 2 In addition, driving stability functions comparable to a two-box brake system (iBooster+ESP-hev) can be implemented via the electric drive motors, for example the motor TM1 on the rear axle and the further motor TM3 on the front axle. This makes it possible to achieve SAE Class 2+ by integrating the brake unit (EHB) into the central control of the driving dynamics system.

[0114] If the brake system shown in WO 2020 / 165255 A1 is further developed so that the electric drive motor establishes a basic braking torque according to function (d) and the pressure supply mechanism is also partially redundant with redundant windings, for example in the following manner: the pressure supply mechanism is implemented as a 2×3-phase, (partially) redundant electronic device (DV1-ECU1, DV-ECU2) and a connection to two vehicle power supplies and / or energy supply devices (BN1, BN2) and data lines (DS1, DS2), then even in the event of a failure of the winding or power semiconductor of the motor end stage, which is the most common failure in EC motors, the pressure supply mechanism can be operated at half power or half torque. Therefore, in a preferred design for 140 bar to 160 bar, a pressure of 70 bar to 80 bar can still be established. Therefore, complete ABS regulation is also possible in the event of a partial failure of the pressure supply mechanism. Furthermore, if at least one traction motor is used in the fault situation to set the basic braking torque in order to generate the basic braking torque, an ABS operation with a maximum deceleration of, for example, 1 g to 1.4 g in particular can also be achieved.

[0115] Furthermore, if, in a single-tank brake system, as for example according to WO 2020 / 165255 A1, normally open inlet / outlet solenoid valves or switching solenoid valves designed for bidirectional volume flow (SV1-SV4 in FIG. 7 of WO 2020 / 165255 A1) are used between the pressure supply mechanism and the wheel brakes in both brake flow directions, that is, from the pressure supply mechanism to the wheel brakes and from the wheel brakes to the pressure supply mechanism, each wheel circuit can be safely diagnosed and isolated from the brake system in the event of a fault. This is not possible in the case of wheel inlet valves used in other cases in the prior art, because non-diagnosable and non-safely closable check valves (e.g., reference numerals 6a-6d in FIG. 1 of DE 10 2013 222 281 A1) are used in parallel with the inlet valves (e.g., reference numerals 50a-50b in FIG. 1 of DE 10 2013 222 281 A1). This makes it possible to operate a three-channel wheel pressure control system in the vehicle dynamics system even in the event of a fault, which enables, for example, vehicle stabilization functions similar to ESP functions and pressure maintenance in the wheel brake circuits. This in turn provides additional degrees of freedom in the braking torque control, in particular in wheel-individualized recuperation. This type of novel switching valve is preferably also described in detail below. Figures 6a to 6d and Figure 9a and Figure 9b The EHB solution according to the present invention is used.

[0116] In any case, a two-channel ABS function is provided at the front axle to ensure steerability according to priority level 3, if no bidirectionally acting normally open valve (switching solenoid valve MV 2k ), the described steerability can also be achieved. In this case, an isolating valve is provided between the front axle and the rear axle. Pressure regulation can alternatively be carried out via the MUX pressure regulation method with pressure buildup and pressure buildup via a switching valve, wherein the switching valve is preferably designed so that the valve seat of the solenoid valve is connected to the wheel brake in order to ensure that there is no brake pressure in the wheel brake. Optionally, an outlet valve can also be provided in order to carry out a pressure release via the outlet valve in the storage container as an alternative to the MUX pressure release. In this regard, it is also pointed out that Figure 9a and Figure 9b .

[0117] As a further alternative, a standard ABS control can be implemented, in which the pre-pressure is set via the pressure supply and a PWM-controlled pressure build-up via the switching valve and a time-controlled pressure release via the outlet valve are carried out. In this case, the valve seat is connected to the pressure supply in order to enable proportional control of the flow cross section. In this case, a normally open switching valve is particularly important in order to prevent the wheel brake from having a brake pressure in the event of a fault at high differential pressures.

[0118] In a sixth advantageous function (f), a yaw moment intervention can be performed for steering support by means of a desired value specification of the vehicle dynamics system. For this purpose, the pressure build-up and pressure release can be correspondingly regulated via an inlet valve (see, for example, reference numeral 11 of DE 10 2018 212 905 A1), so that the hydraulic braking force is modulated by the electric braking force. This can be done during the pressure build-up via PMW control of the inlet valve and during the pressure release alternatively via a MUX method via the inlet valve or an isolating valve or via a pressure release through an outlet valve.

[0119] The solution is based on Figure 6a and Figure 9a The solution with EHB-Z and EHB-VA is simpler, in particular if the wheel inlet valve is designed as a normally open inlet / outlet valve designed for bidirectional volume flow, so that due to the lack of a non-return valve, pressure can be maintained in the case where the pressure supply has a lower pressure level than the wheel brake and the hydraulic braking torque is to be kept constant in the recuperation strategy. In addition, there is a degree of freedom for releasing the braking torque via the bidirectional inlet / outlet valve with simultaneous return of the piston of the piston-cylinder unit of the pressure supply or via the outlet valve in the reservoir, which is advantageous for achieving very dynamic braking torque interventions.

[0120] In the seventh advantageous function (g), wheel-individualized braking torques can be generated for wheel-individualized recuperation by means of the desired value presetting of the vehicle dynamics system. For this purpose, the pressure build-up and pressure release must be regulated accordingly via the inlet valve (see reference numeral 11 of DE 10 2018 212 905 A1), so that the hydraulic braking force is modulated by the electric braking force. This can be done during the pressure build-up via PMW control of the inlet valve and during the pressure release alternatively via the MUX method via the inlet valve or the isolating valve or via the pressure release through the outlet valve.

[0121] According to the following detailed Figure 6a , Figure 6c and Figure 9a to Figure 9b The solution with EHB-Z and EHB-VA is simpler and significantly more flexible, especially if the wheel inlet valve is designed as a normally open inlet / outlet valve MV2k , so that due to the lack of a non-return valve the pressure can be maintained in the case where the pressure supply has a lower pressure level than the wheel brakes and the hydraulic braking torque is to be kept constant in the recuperation strategy. Figure 9a In the implementation of the brake unit (EHB) or Figures 6a to 6d In a variant of the invention, in which no outlet valves are provided at the wheel brakes or only at some of the wheel brakes, the pressure relief takes place exclusively via the inlet / outlet valves. Figures 6a to 6d as well as Figure 9b In the embodiment of the invention, there is a degree of freedom in releasing the braking torque via the inlet / outlet valve or via the outlet valve. This is particularly advantageous in the sense of maximizing recuperation in order to achieve a very flexible braking torque intervention. In the recuperation strategy via the driving dynamics system, the braking torque curves of the at least one electric traction motor and the brake unit (EHB) can be synchronized so that the recuperation is maximized. If the recuperation via the at least one electric traction motor is limited, for example when the battery is fully charged, the kinetic energy is dissipated via the brake unit (EHB); if the battery allows feeding, the recuperation is mainly via the electric traction motor.

[0122] In functions (e), (f) and (g), normally open and cost-effective inlet / outlet valves MV 2k This is important because it can avoid brake circuit failure and the wheel circuit can continue to operate even if the switching valve leaks. In this way, even if the switching valve leaks, four-channel wheel pressure control operation can be maintained or even if the wheel circuit is shut down, emergency steering or steering support can be performed using three-channel wheel pressure control operation, thereby simplifying the redundancy requirements of higher-level (SAE level 3-4) electric servo steering for automated driving. These functions (e) and (f) are particularly important for the overall cost of the main chassis control actuator, brake and steering device. If the electric servo steering is implemented completely redundantly, two steering actuators are required. In contrast, the brake can be used as an effective solution for meeting the SAE requirements of level 3-4 by function (f) as a redundant function for steering; it also has the advantage that units with different structures can be used for redundant steering functions, thereby eliminating product quality defects as a source of failure in steering units with the same structure. The steering function via the brake unit (EHB) can also be provided as a third fallback level for an already redundantly implemented electric servo steering EPS with two steering actuators or as a second fallback level for an EPS that is not redundant or is only partially redundant, for example with 2×3-phase steering actuators and redundant controllers. In addition, the steering unit (EHB) can support the steering at the second axle, where no EPS is provided, or also perform yaw moment interventions in addition to the steering interventions for stabilizing the vehicle, for example during μ-Split braking.

[0123] Thus, the SAE requirements for autonomous driving level 3 can also be met using the functions explained above with a hydraulic brake system having only one pressure supply. In order to meet SAE levels 4 and 5, the same is implemented according to Figure 6a and 6b All the prerequisites for the expansion according to the invention with a single-box brake system are met. If the pressure supply is designed redundantly and the electric traction motor plays a supporting role in the build-up of the braking torque as in function (b), an emergency brake function with a commercially typical dynamics of 150 ms can also be ensured. As a result, under normal circumstances, although the maximum dynamics of 90 ms of the solution according to the invention cannot be achieved, a TTL of 150 ms to 200 ms with reasonable losses can be achieved. This corresponds to the performance data of commercially typical brake boosters.

[0124] Similarly, brake systems for SAE levels 3 and 4 (see, for example, WO 2018233854A1) can only use the pressure dynamics of the ESP pump in the event of a brake booster failure, which according to current responsibility manuals only allows a pressure build-up of 450 ms to 50 bar. In the driving dynamics system, it is also possible to use the braking torque build-up dynamics of the electric traction motor to support the pressure build-up via the ESP pump. Depending on the power level of the electric traction motor, a TTL of approximately 150 ms to 250 ms can also be achieved for such a two-tank brake system with a weak ESP pump. The emergency braking function in the event of a failure is then equivalent or approximately equivalent to normal operation.

[0125] The integration of the brake system into the central control system, using the synergies and functional support described above, ultimately offers the potential to dispense with the hydraulic fallback level via the brake pedal (see FIGS. 6 to 7). Figure 6c ), and either introduce an electric pedal or completely dispense with the pedal. Thus, a brake system with only one pressure supply in a structural unit (single-tank brake system) with an FDS according to the invention has the potential to reach a capability for AD class 5.

[0126] In the second "architecture II", an axle module is provided instead of a hydraulic brake system that is centrally controlled via a domain. For example, the axle module has at least two brake modules selected from:

[0127] - electric drive motor,

[0128] - electromechanical brakes (EMB) for each wheel,

[0129] -Electrohydraulic pressure regulator for each axle (EHB-VA, EHB-HA),

[0130] There are wheel control valves for controlling the brake torque of two wheels of each axle.

[0131] For example, the axle module can include an electric drive motor, by means of which the wheels of the axle (VA, HA) can be driven and regeneratively braked, and an electromechanical brake unit (EMB) for each of the two wheels of the axle or a common electrohydraulic brake unit (EHB-VA, EHB-HA) for both wheels of the axle (VA, HA).

[0132] In the second embodiment, unlike the first embodiment, a controller (S-ECU) is provided for each axle. VA 、S-ECU HA ), which has a communication interface to a central control unit (M-ECU domain) and synchronously controls the selected brake modules of the axles. In contrast to normal operation of the brakes, synchronization is particularly advantageous for control operation, since the different delay times and time courses in the build-up of braking torque and the release of braking torque are optimally coordinated with one another by the different brake modules. In addition, responsibility issues are resolved with this structure, since the provider of the electric axle is then responsible for the overall drive and brake management. In this second embodiment, different variants are possible:

[0133] a) Electromechanical brake unit EMB in combination with an electric traction drive, particularly advantageously for the front axle of a vehicle (see Fig.12a );

[0134] b) An electromechanical brake unit EMB in combination with an electrohydraulic EHB pressure regulator with wheel control valves, particularly advantageously for the front axle (see Fig.12 b);

[0135] c) An electric traction motor for each wheel of the axle in combination with an electrohydraulic pressure regulator EHB with wheel-control valves, particularly advantageously for the rear axle (see Fig.12 c); and

[0136] d) Electric traction motors for the axles in combination with electrohydraulic pressure regulators EHB with wheel control valves, generally advantageously for the front and rear axles (see Fig.12 d)

[0137] The combination of an electric motor or an electromechanical brake unit EMB with an electrohydraulic brake unit EHB is particularly advantageous, since the advantages of both brake torque generators can be ideally combined:

[0138] a) Electrohydraulic brake units EHB are highly dynamic and insensitive to high braking torques during pressure release, whereas electric drive motors or electric brake units EMB have their greatest advantages at low braking torques in braking torque gradients. In addition, their costs increase in their designs for higher loads.

[0139] b) The electrohydraulic brake unit EHB is significantly more cost-effective than the electric brake unit EMB. Compared with a pressure regulator for the rear axle with wheel control valves for both wheel brakes, the costs in the case of an electric brake EMB are approximately twice as high. In the case of an electrohydraulic pressure regulator for the front axle with wheel control valves for both wheel brakes, the costs are only 10% higher, while in the case of an electromechanical brake EMB for the front axle the costs are a further 50% higher than in the case of the rear axle. The reason for the disproportionately higher costs of the electromechanical brake EMB is the higher braking torque that must be achieved for the front axle and the necessity of providing two motors for each wheel in premium cars or SUVs.

[0140] c) Electrohydraulic brake unit EHB as pressure regulator in the embodiment The combination of the PPC-Gen2 pressure regulation method described below with an electric traction motor or an electromechanical brake unit EMB can fully utilize the advantages of the new PPC-Gen2 pressure regulation with very precise brake torque regulation. Dead times in the PPC-Gen2 method, for example caused by partial multiplex pressure regulation operation, can be compensated by regulation via the traction motor or EMB, since such brake units are fully capable of achieving similar brake torque gradients.

[0141] The achievable pressure-torque gradient is shown in Figure 1. Fig.13a and 13 The typical braking torque gradients in b are explained further based on a powerful electric traction motor and with an EMB, EHB operated with AV / EV technology and PPC-Gen2 and are described in detail below.

[0142] Used as a hydraulic foundation principle Figure 9a and 9b The following is an implementation example further described in detail.

[0143] Functions (a)-(g) implemented in “Architecture I” can all also be performed in “Architecture II”, even with more degrees of freedom, since two pressure supplies with pressure control valves are available per axle, which are also preferably implemented redundantly.

[0144] In the third "Architecture III", wheel modules are provided instead of conventional electro-hydraulic EHB brake devices, wherein an electric traction motor and an electromechanical brake EMB are provided for each wheel module. Wheel modules with electric traction motors enable very great flexibility in platform design. This concept is extremely flexible and has more redundancy than conventional brake systems, because in the event of a failure of one wheel module, all core functions of the brake and brake regulation, vehicle stabilization and steering can still be performed using the remaining wheel modules. The disadvantage is the high cost, because an electric traction drive and an electromechanical brake unit EMB are required for each wheel. In addition, the electrical components are arranged in the area of ​​the unsprung mass and are thus subjected to high mechanical loads. Advantageously, the EMB can together depict the parking brake function, thereby reducing costs.

[0145] As explained in the first embodiment, the synchronous use of the electric traction motor and the electromechanical brake unit EMB via the vehicle dynamics system is advantageous, in particular if the braking power is distributed in the foundation brake function (see in particular function (a) of "Architecture 1" for this purpose). As a result, the fading effect can be suppressed or reduced by heating the friction brake, and in the emergency brake function AEB, the braking torques of the traction motor and the electromechanical brake unit EMB can be added (see function (b) of the first embodiment "Architecture 1").

[0146] In contrast to function (g) of "Architecture I", wheel-individualized recovery can also be realized more simply. Axle-individualized recovery (function (c) in "Architecture 1") is of course also conceivable.

[0147] The use of function (f) is decisive, in which a basic braking torque is generated in control mode via the traction motor and the braking torque is modulated in control mode by means of the electromechanical brake unit EMB. Alternatively, the basic braking torque can also be generated by the electromechanical brake unit EMB and the braking torque can be modeled by means of the electric traction motor. For critical driving situations (e.g. in μ-Sprung), a common braking torque can even be established or released simultaneously by means of the electromechanical brake unit EMB and the electric traction motor, so that a highly dynamic braking torque adaptation is available overall. If each wheel has a controller (M-ECU-wheel 1, M-ECU-wheel 2, M-ECU-wheel 3, M-ECU-wheel 4) for synchronous braking torque control of the EMB and the electric traction motor, a common control of the braking torque is thus easily possible. This also makes it possible to minimize the time lag when the braking torque changes.

[0148] The advantages of a coordinated braking torque reduction are great, since the technical challenges of the electromechanical brake EMB are posed especially at high braking torques, since the EMB tends to be tensioned more at high actuating torques and the separation process of the brake pads is more problematic and leads to high costs. The problems are significantly alleviated by applying the basic braking torque via the traction motor. In addition, the support function allows a considerable reduction in the costs of the electromechanical brake EMB, wherein the effect increases disproportionately with the actuating force or the braking torque. If, for example, 30% of the required basic torque is applied by the electric traction motor, the costs of the electromechanical brake EMB can be reduced by more than 30%, since the size of the electromechanical brake EMB can be relatively smaller. Due to the axle load distribution during braking (typically 60% to 70% of the load is at the front axle and 40% to 30% of the load is at the rear axle), it is advantageous if the electric traction motor of the front axle is implemented more strongly than the electric traction motor of the rear axle. This makes it possible to use common components of the electric brake unit EMB for the rear axle and the front axle, since the axle load distribution is compensated for by the higher braking power of the motor at the front axle during braking with a higher braking power.

[0149] The driving dynamics system with wheel modules is a solution that fully meets the requirements of SAE Level 5 due to redundancy. However, due to the high costs (four traction motors + four electromechanical brakes), this solution is more of a niche solution for specific applications from a chassis control point of view, but with other advantages over the higher costs, such as flexibility in the production and design of different vehicle concepts.

[0150] In another embodiment of the driving dynamics system, a special combination brake with a hydraulic brake (EHB-VR, EHB-VL) for the front axle with a pressure regulator for each wheel of the front axle and an electromechanical brake unit as an EMB module (EMB1, EMB2) at each wheel of the rear axle is provided, preferably with an integrated electronic parking brake, for example by redundantly implementing the electronics of EMB1, EMB2 or implementing a self-locking mechanism of the transmission of EMB1 and EMB2, for example by using a trapezoidal lead screw made of plastic. The electrohydraulic EHB-VR pressure regulator or EHB-VL pressure regulator can be implemented as a piston-cylinder unit without wheel control valves or simplified as a pump, in particular with a gear pump per pressure regulator. If a piston pump is used, for example a 2k pump of a standard ESP unit, at least one valve device is required for pressure release, while the gear pump takes over the function of the piston-cylinder unit and can both build up and release the braking torque.

[0151] "Architecture II" is particularly suitable for special combined brakes, where the pressure regulators of each axle are combined and controlled via the axle controller S-ECUVA and S-ECU HA The synchronization of functions a) to f) can be easily coordinated. However, other architectures are also conceivable in which the controller of each brake torque regulator is connected to the central control unit M-ECU. 域 The communication and central control unit transmits the desired braking torque to the control electronics of the brake torque regulators (EHB-VR, EHB-VL, EMB-HL, EMB-HR) of the wheel brakes and to at least one traction motor (TM1, TM2, TM3, TM4). The functions (a) to (g) of the driving dynamics system explained above can also be implemented independently of the selected architecture, wherein the greatest potential also lies in the cost and weight optimization of the friction brakes, for example by using drum brakes at the front axle and smaller disc brakes at the rear axle for the electromechanical brake unit EMB. It is therefore particularly advantageous to use the braking effect of the electric traction motor at the front axle for the combined brake.

[0152] The specific combined solution is better than a solution with an electrohydraulic brake unit EHB-1 or EHB-ZA with wheel control valves at the front axle and an electromechanical brake unit EMB at the rear axle (e.g. Figure 6c The specific combination solution, however, has the advantage of an additional degree of freedom in the positioning of the EHB-VR and EHB-VL modules close to the wheels and allows a simpler expansion than an electromechanical brake unit EMB at the front axle. In addition, the specific combination solution makes the manufacturer of the pressure regulating unit, in particular a new company, independent of the supplier of the solenoid valves and the required technology for pressure regulation with solenoid valves, which is firmly in the hands of established brake manufacturers.

[0153] Furthermore, the specific combined brake can be easily applied similarly to the electromechanical brake unit EMB. If a gear pump is used instead of the piston-cylinder unit, a solution can also be realized at reasonable cost. In particular, the cost reduction potential through the driving dynamics system and functions (a) to (g), as also explained below for further embodiments and structures, is also significant in this solution.

[0154] The following inventive object is to achieve great functional, redundancy and cost advantages by means of the vehicle dynamics control of architectures I to III and by means of a specific brake combination:

[0155] Improvements / Applications / New Features:

[0156] - Use of the electric traction motor in controlled operation during ABS operation, in particular on surfaces with a low coefficient of friction (snow, ice), to shorten the braking distance, where the greater braking torque gradient of the electric traction motor has advantages over known ABS systems with a storage chamber (see standard ESP systems with slow pressure release in the storage chamber).

[0157] - Use of the electric traction motor for ASR operation at start-up with torque regulation and motor speed regulation, instead of the known solution of braking the rear wheels by means of electrohydraulic brakes EHB.

[0158] - Increase the braking torque to 100ms instead of 150ms and reduce the braking distance accordingly

[0159] Improvement of the emergency braking function AEB, especially at high speeds and at the risk of an accident. - Combined yaw torque intervention for vehicle stabilization or steering using torque intervention, which is generated by means of the electric traction motor and by the braking torque of the electrohydraulic brake unit EHB.

[0160] - Combined braking intervention by the electric traction motor and the electrohydraulic brake EHB in control mode, for example in the case of dynamic changes in road conditions, such as μ-Sprung, where a rapid pressure release is required.

[0161] - Using an electrohydraulic brake unit EHB in a multiplex method with torque-controlled ABS control via the electric traction motor, thereby avoiding dead times in multiplex systems.

[0162] - Using the advantages of a closed hydraulic brake system for the rapid implementation of the core functions ABS and ESP and the automation of new software functions via a central OTA update, for example to enable a software update when transitioning from SAE Level 2 to SAE Level 3-5.

[0163] EBV control with a further electric traction motor at the rear axle and an electrohydraulic brake EHB at the front axle.

[0164] - Redundant ASR function via electric traction motor or electro-hydraulic brake unit EHB.

[0165] Advantages through cost reduction and weight reduction:

[0166] - The use of an electric traction motor for reducing the thermal load on the brake caliper during multiple braking (the so-called AMS fading test) and thus streamlining the electrohydraulic brake system, for example the electrohydraulic brake unit EHB is designed for a locking pressure and an additional 20% to 40% reserve, that is to say 120 bar to 140 bar instead of 200 bar to 200 bar, optionally for a pressure lower than the required locking pressure (60 bar to 80 bar) even when braking via the electric traction motor is successfully achieved using reliable energy management even with a full battery.

[0167] The use of an electric traction motor serves to reduce the thermal load on the brake calipers and enables the use of cost-effective drum brakes at the rear axle.

[0168] - Reduce dust and wear on the brake system by braking primarily with the aid of the electric traction motor.

[0169] - The electric brake unit EMB is streamlined by supporting the braking torque by an electric traction motor, in particular at the front axle of the vehicle, but also at the rear axle.

[0170] - Instead of a single box with a powerful EC motor, an electrohydraulic brake EHB with a simple 2-K pump with relatively low power is used and the emergency braking function within 150 ms is mapped by a corresponding power of the electric traction motor in combination with a standard ESP with TTL=500 ms.

[0171] - Smaller solenoid valves can be used by describing the highly dynamic pressure buildup with the aid of the electric traction motor.

[0172] Improvements through redundancy:

[0173] - Use of the electric traction motor for braking in the event of failure or partial failure of the brake system.

[0174] - Use of the electric traction motor for maintaining rapid emergency braking AEB with TTL=150ms even when the primary brake system fails.

[0175] - The electric traction motor is used to maintain the EBV function even if the brake circuit of the rear axle fails.

[0176] - Use of electric traction motor in case of brake circuit failure.

[0177] - Use of the electric traction motor when ESP fails.

[0178] - In the event of a steering failure, the steering intervention at the front axle is supported by using the electric traction motor or by yaw torque intervention at the rear axle.

[0179] - Redundant ASR function via electric traction motor or electro-hydraulic brake unit EHB. BRIEF DESCRIPTION OF THE DRAWINGS

[0180] In the following, the invention is described with the aid of a number of exemplary embodiments which are explained in detail with reference to the figures. Here, it is shown:

[0181] Figure 1a : The attenuation effect as the basis for the design of standard brake equipment during AMS testing;

[0182] Figure 1b : Using a masking strategy for regenerative braking without a driving dynamics system according to the prior art;

[0183] Figure 2a : Driving dynamics system "Architecture I": combination of hydraulic brake systems EHB-Z, EHB-VA and electric traction motors TM1, TM2, TM3;

[0184] Figure 2b : Driving dynamics system "Architecture I": hydraulic brake system combined with electric traction motor;

[0185] Figure 3 : A novel cover strategy using the driving dynamics system and one or more powerful electric traction motors;

[0186] Figure 4 : AEB time gain with braking via electric traction motor and electrohydraulic brake unit EHB with adapted EBV function;

[0187] Figure 5 : ABS control operation with electrohydraulic brake unit EHB and generation of basic braking torque via electric traction motor;

[0188] Figure 5a : Typical ABS time course with wheel speed, pressure and valve time during brake torque regulation with electrohydraulic brake unit EHB;

[0189] Figure 5b : With optimized ABS time course of wheel speed, pressure and valve time when utilizing the braking torque regulation of the electric traction motor;

[0190] Figure 5c : ABS regulation operation using the combination of electrohydraulic brake unit EHB and electric traction motor in μ-Sprung;

[0191] Figure 5d : ABS controlled operation in low μ conditions using an electrohydraulic brake unit EHB in combination with an electric traction motor at the rear axle;

[0192] Figure 6a : Concept A for the driving dynamics system “Architecture I”: EHB-Z for wheel-individualized control of the front and rear axles in combination with electric traction motors at the front and rear axles;

[0193] Figure 6b : Concept B for the driving dynamics system "Architecture I": EHB-Z with wheel-individualized control for the front axle combined with basic braking torque for the rear axle, ABS control at the rear axle by means of an electric traction motor;

[0194] Figure 6c : Concept B for the driving dynamics system "Architecture I": EHB-Z with wheel-individualized control for the front axle combined with basic brake torque for the rear axle, ABS control at the rear axle by means of an electromechanical brake unit EMB;

[0195] Figure 6d : Concept D for the driving dynamics system "Architecture I": EHB-VA for wheel-individualized control at the front axle, brake and ABS control at the rear axle using only the electric traction motor;

[0196] Figure 7a : 250kW motor characteristic curve family with high-power motor and power boost via the new RSP-4Q inverter;

[0197] Figure 7b : The structure of the new RSP-4Q inverter;

[0198] Figure 8 to Figure 8c : Normally open inlet / outlet valve MV for pressure build-up and pressure relief at high pressure gradients and brake pressures 2k ;

[0199] Figure 9a : With inlet / outlet valve MV 2k New pressure regulation (PPC-Gen-V1);

[0200] Figure 9b : With inlet / outlet valve MV 2k New pressure regulation (PPC-Gen2-V2);

[0201] Fig.10 : Driving dynamics system "Architecture II": with axle control electronics S-ECU VA and S-ECU HA Electric axle modules;

[0202] Fig.11a : Driving dynamics system "Architecture II": Electric axle module I with two electric brake units and one electric traction motor;

[0203] Fig.11b : Driving dynamics system "Architecture II": Electric Axle Module II with one electrohydraulic brake unit and two electric brake units;

[0204] Fig.11c : Driving dynamics system "Architecture II": Electric axle module III with an electrohydraulic brake unit and an electric traction motor;

[0205] Fig.11d : Driving dynamics system "Architecture II": Electric axle module IV with an electrohydraulic brake unit and two electric traction motors;

[0206] Fig.12 : Comparison of braking torque gradients and operating ranges of the electric traction motor TM, the electric hydraulic brake unit EHB, and the electric brake unit EMB;

[0207] Fig.12a : Decision heuristics with evaluation of characteristic curve families, core data and signals;

[0208] Fig.13 : Driving dynamics system "Architecture III": Wheel module with wheel control electronics for electric brake unit and electric traction motor; and

[0209] Fig.13a : Driving dynamics system "Architecture III": wheel module with four electric brake units and four electric traction motors. DETAILED DESCRIPTION

[0210] Figure 1d A typical simulation of the AMS test is shown, according to which the brake system is designed according to the prior art. In the simulation, 10 consecutive brakings starting at 100 km / h are simulated. If the so-called AMS fading test is used as the basis for measuring the maximum pressure (Brake Manual 5th edition, Chapter 6.3.2, Figure 6.10), the wheel brakes on the front axle typically heat up to about 600° C. and the wheel brakes on the rear axle to about 500° C. The pedal force in the case of a standard vacuum brake booster then increases by about 80%, i.e. the brake system must be designed for a pressure that is 80% higher for fading situations than is required for the normal locking pressure. Therefore, with a corresponding safety reserve, typical brake systems are designed for a maximum pressure of 200 bar to 220 bar.

[0211] Figure 1e The brake management with electrohydraulic brakes that is common in the current market with electric traction motors is shown. This process is described in detail, for example, in the 5th edition of the Brake Manual, chapters 19.3.2 and 19.3.3 and is available in Figure 1a The management is now expanded as the core concept of the present invention. Characteristically, at low vehicle speeds (region B), hydraulic braking is performed at the beginning of braking, while generator braking is gradually increased at speed v1 and gradually reduced up to speed v2; that is, hydraulic braking is performed at low vehicle speeds (v1<10 km / h, region B) and high vehicle speeds (v2>60 km / h, regions E2, D), respectively, and not regenerative braking. In addition, the available potential of regenerative braking is not fully utilized, for example, above the M between v1 and v2. max The braking torque of the brake is stronger and the regenerative braking in the speed range >v2. That is, although up to M max,TM A higher braking torque may be available, but this is not fully utilized in the speed range (region E1). This is usually technically conditional, for example when the brake system used is not designed for higher recuperation. This is limited, for example, in the system described in DE 10 2012 211 278 A1 by the fact that the storage chamber of the ESP-hev-unit can only absorb a limited volume, so that the coverage is limited.

[0212] Furthermore, at higher decelerations and speeds, safety aspects come into play: therefore, for example, no regenerative braking is performed in the case where, in the case of ABS, the braking torque of the electric traction motor could lead to wheel locking—the driving dynamics system according to the invention first implements a remedy by central control of the electric traction motor and the electrohydraulic brake unit. Therefore, in the masking strategy according to the prior art, no regenerative braking is provided in areas E1 and E2.

[0213] For the reasons mentioned, the potential for regenerative braking and optimization of the friction brakes is not fully utilized in the known systems for AMS fading situations, because AMS fading situations occur precisely at speeds from about 100 km / h and under full braking. There, pure hydraulic braking is used according to the prior art (see FIG. 1 ). If the braking power (M ) of the electric traction motor, which is exemplarily up to 30% in the AMS test, is taken over, el.TM,AMS ), the attenuation effect is significantly reduced, since the heating of the brake system is significantly lower. The brake system can then be designed for a significantly lower maximum pressure, for example 140 bar to 160 bar. The maximization of the vehicle dynamics control according to the invention has three effects with significant cost and weight savings: 1. Regeneration can be maximized, which increases the range of the electric vehicle and can be used to operate a heat pump,

[0214] 2. The friction brake can be simplified, for example through simpler cooling, lower wear and smaller brake discs, and cost-effective drum brakes can replace disc brakes. 3. The simplification of the electro-hydraulic brake is feasible, in particular by utilizing a smaller EC motor with a lower maximum torque, a wheel control valve design for a lower maximum pressure, a reduced weight of the electro-hydraulic brake unit EHB and a smaller volume of the pressure supply unit of the electro-hydraulic brake unit.

[0215] Figure 2 The electric traction motor (TM3) at the front axle and / or the electric traction motor (TM1, TM2) at the rear axle are shown with a plug-in Figure 2 The central control unit hereby takes over the brake torque control of the electric traction motors TM1, TM2, TM3 and the electrohydraulic brake units EHB-Z, EHB-VA for at least one of the following functions:

[0216] (A) foundation braking with thermal and energy management of the energy supplied and removed (electrical energy, thermal energy) by the traction motor;

[0217] (B) AEB with electronic brake force distribution (EBV);

[0218] (C) regenerative braking at multiple axles;

[0219] (D) ABS control with basic brake torque support and / or common brake torque control;

[0221] (E) Braking operation when the electro-hydraulic brake unit EHB-Z, EHB-VA fails;

[0222] (F) yaw moment intervention by means of wheel-individualized brake torque intervention; and / or

[0223] (G) Wheel-individualized braking torque intervention for wheel-individualized regenerative braking.

[0224] The vehicle dynamics system sends desired values ​​to various units, wherein the desired values ​​include in particular a desired braking torque or a desired braking pressure. For certain functions (e.g. the functions (C), (E), (F) described above), desired signals for pressure control or pressure regulation are also predefined, for example control signals for switching durations of solenoid valves for functions such as the opening time or the PWM frequency in throttle operation and / or for the pre-pressure of a pressure supply device for building up pressure or releasing pressure.

[0225] In addition, M-ECU 域Can also have an interface to a controller or autonomous driving M-ECU AD The vehicle can also be controlled by the camera and can evaluate additional information that is helpful for effective and predictive control. This is, for example, camera information about the road surface conditions (snow, ice, rain) or information about the environment (distance to pedestrians and / or other vehicles).

[0226] Figure 2a An exemplary configuration of a vehicle architecture of a driving dynamics system is shown, with hydraulic and signal lines between the units and sensors. A central control unit M-ECU preferably comprises three microcontrollers μC1, μC2, μC3 for implementing a 2-out-of-3 architecture 域 In particular, the redundant data lines communicate with the controller of the electro-hydraulic brake unit (M-ECU BM ) and the electric traction motor TM1 (optionally TM2) of the rear axle and the electric traction motor TM3 of the front axle communicate.

[0227] Central Control Unit M-ECU 域 In particular, it can have at least one very powerful microcontroller and a large memory (measured in the gigabyte range) in order to be able to implement automatic applications via artificial intelligence (AI) before the vehicle is put into operation for the first time and / or during vehicle operation. Alternatively, instead of the domain computer, it can also use the central computer or can use the typically larger resources of a central computer designed for processing multimedia data, in particular for applications via AI.

[0228] Central Control Unit M-ECU 域 Receiving wheel v R1 -v R4The data of the wheel speed sensors and preferably further sensor signals S1, S2, Si etc. The sensor signals S1, S2, Si can be provided by yaw moment sensors, acceleration sensors and / or weight sensors, which are important for the central control via the vehicle model, because they enable or at least simplify the optimization of the central control. Therefore, the weight sensor can be used advantageously in order to adapt the recovery strategy to the weight. The yaw moment sensor is helpful for driving dynamics interventions, such as torque vectoring or ESP yaw moment intervention, and the acceleration sensor is helpful in calibrating the relationship between the brake pressure of the hydraulic brake unit (EHB) and the obtained brake torque or the brake pressure and the obtained vehicle deceleration. It is also possible to use data from other sensors or autonomous driving systems, such as data from camera and lidar sensors, map material or data in interaction with the environment and other vehicles, for example in Car2X (V2x) or Car2Car (V2V) communication, in order to carry out traffic-specific braking torque interventions or target-oriented deceleration of the vehicle and to operate the vehicle at an adapted speed or early deceleration in the event of a fault, such as in the event of a partial failure with reduced maximum deceleration.

[0229] In addition, an electric servo steering EPS on the front axle and an electric parking brake (EPB1, EPB2) on the rear axle are advantageously provided for communication with the central domain. The engagement of the EPS enables coordinated driving dynamics interventions, such as torque vectoring, support for steering or electric servo steering of the vehicle in the event of EPS failure or partial failure, supplemented by ESP yaw torque intervention via the electrohydraulic brake unit EHB. In addition, the engagement of the electric parking brake EPB is advantageous because the parking brake can also perform dynamic braking functions or emergency functions in addition to ensuring a pure stationary state, as described, for example, in WO2020165255 A1.

[0230] Figure 2b An exemplary design of a further vehicle architecture of the driving dynamics system according to the invention is shown, which has an EHB-Z with hydraulic lines and signal lines between the brake unit and the sensor. A central control unit M-ECU preferably includes three microcontrollers μC1, μC2, μC3 for implementing a three-out-of-two architecture 域 In particular, via redundant data lines with two redundant controllers ECU1 EHB and ECU2 EHB Hydraulic brake unit (M-ECU BM ) controller and the electric traction motors TM1 and TM2 of the rear axle and the electric traction motor TM3 of the front axle. Figure 2bIn contrast, in the EHB-Z there is no integrated pedal and only hydraulic lines to the wheel brakes of the rear axle are provided and an electric traction motor is provided for each wheel of the rear axle, so that the electric traction motor performs the braking torque regulation and recuperation braking for the various functions ABS, ASR, ESP, while the electrohydraulic brake unit EHB-Z only provides the basic braking torque. Further details on the hydraulic layout of the EHB-Z are given in Figure 6b Shown in.

[0231] In the central control unit M-ECU 域 Middle receiving wheel v R1 -v R4 The data of the wheel speed sensors and preferably other sensor signals S1, S2, Si, etc. The sensor signals S1, S2, Si can be provided by yaw moment sensors, acceleration sensors and / or weight sensors, which are important for the central control via the vehicle model because they enable or at least simplify the optimization of the central control. Therefore, the weight sensor can be used advantageously in order to adapt the recovery strategy to the weight. The yaw moment sensor is helpful for driving dynamics interventions, such as torque vectoring or ESP yaw moment intervention, and the acceleration sensor is helpful in calibrating the relationship between the brake pressure in the hydraulic brake unit (EHB) and the obtained brake torque or the brake pressure and the obtained vehicle deceleration. It is also possible to use data from other sensors or autonomous driving systems, such as data from camera and lidar sensors, map material or data in interaction with the environment and other vehicles, for example in Car2X (V2x) or Car2Car (V2V) communication, in order to carry out traffic-specific braking torque interventions or target-oriented deceleration of the vehicle and to operate the vehicle at an adapted speed or early deceleration in the event of a fault, such as in the event of a partial failure with reduced maximum deceleration.

[0232] In addition, an electric servo steering EPS on the front axle and an electric parking brake (EPB1, EPB2) on the rear axle are advantageously provided for communication with the central domain. The engagement of the EPS enables coordinated driving dynamics interventions, such as torque vectoring or, in the event of a failure or partial failure of the EPS, supplementary ESP yaw torque interventions via the hydraulic brake unit EHB for steering or for support of the electric servo steering of the vehicle. In addition, the engagement of the electric parking brake EPB is advantageous because, in addition to ensuring a pure stationary state, the parking brake can also perform a dynamic braking function or an emergency function, as described, for example, in WO2020165255 A1.

[0233] Figure 3A masking strategy for the driving dynamics system is shown, which has full utilization of the braking force of the electric traction motor over the entire speed curve of the vehicle and up to the maximum braking torque of the electric traction motor used. Full utilization is possible in the driving dynamics system by: Figure 2a As shown, the central area has all the important information so that the braking effect can be adapted very quickly via the electric motor with minimal time delay in critical driving situations, such as during ABS control operation. New electric motors in high-voltage technology (>700 V) can increase or reduce the electric braking torque via the electric motor very dynamically at 10,000 Nm / s to 30,000 Nm / s. Therefore, in the case of ABS, the braking torque can be released almost as quickly as with hydraulic brakes (typically 1,000 bar / s to 2,000 bar / s = 20,000 Nm / s to 40,000 Nm / s) by the electric traction motor at the axle before the electrohydraulic brake unit EHB takes over the ABS control. The control strategy that jointly uses the electric traction motor and the electrohydraulic brake unit EHB in ABS operation is Figure 5a Continuing to explain in . Although the first control cycle is thus not completely optimal, there are no safety-critical situations where the vehicle would become unstable. Furthermore, in critical driving situations where automatic emergency braking (AEB) can be used, the disadvantages of the first control cycle can be overcompensated by shortening the TTL.

[0234] In the diagram, the torque-speed characteristic diagram of the electric drive motor of a plug-in hybrid or electric vehicle (e.g., the BMW i3) with a vehicle weight of 1365 kg has been used as an example. The electric traction motor has a maximum power of approximately 130 kW and a maximum torque of 250 Nm and acts with a transmission ratio of 9.5, which means that up to 2400 Nm of torque can be used at the axles of the vehicle for driving and for deceleration. If the maximum permissible vehicle weight of 1710 kg and a weight distribution of 40% at the rear axle and 60% at the front axle during braking with maximum deceleration are taken as the basis, an axle braking torque of 3400 Nm at the front axle and an axle braking torque of 2465 Nm at the rear axle are required. This makes it possible to brake the rear axle completely electrically up to a speed of approximately 70 km / h.

[0235] In the design point for the AMS fading test, approximately 50% of the braking power can be provided at the front axle at a speed of 100 km / h, and even close to 70% at the rear axle. This in turn means that the brakes are only subjected to half the friction power at the front axle and only 30% at the rear axle.

[0236] The high additional braking torque available over a wide speed range can be used to significantly reduce the heating of the friction brakes, in addition to the AMS test conditions at 100 km / h and also at high speeds, where a large amount of the kinetic energy of the friction brakes is absorbed. The latter is advantageous for sports vehicles, where very expensive ceramic brakes are typically used. In addition, the thermal load on the rear axle can be completely relieved in the speed range of up to 70 km / h; the rear axle can be very strongly unloaded, especially even in the critical AMS test. This allows the use of cost-effective drum brakes.

[0237] The central control unit of the vehicle dynamics system, which preferably also detects the weight of the vehicle, can then also increase braking via regenerative braking when the vehicle is lightly loaded, so that the recuperation strategy is adapted to the vehicle load.

[0238] The problem is the feasibility of the battery to absorb high pulse powers, especially in a high state of charge. For this special case, it is applicable not to feed power back into the battery, but to dissipate the power internally in the electric traction motor at least partially by means of intelligent field-oriented vector control (Id, Iq) so that no energy is re-directed. Alternatively, an additional resistor can be used, at which the heat can be dissipated. The heat generated via the resistor can then advantageously also be used to heat the vehicle or to cool the vehicle via a heat exchanger. The feasibility of energy management has already been described above in additional details.

[0239] If a special inverter is additionally used, by means of which the windings of the motor can be connected alternatively in series or in parallel (RSP-4Q inverter), additional torque assistance is possible at higher motor speeds or at higher vehicle speeds. This also makes it possible to increase the braking torque for generator braking at higher vehicle speeds and thus recover more kinetic energy. Alternatively, it is possible, for example, to Figure 4 As shown in , at high speeds the TTL time (English: Time-to-Lock) is further reduced, which can also be used advantageously to shorten the braking distance, since in addition to the hydraulic brake an additional electric braking is possible.

[0240] Figure 4 The diagram illustrates how the inventive control of the vehicle dynamics system can be used to implement the inventive function of emergency braking AEB (function B) by meaningfully adapting the EBV control in the context of shortening the braking distance in addition to the braking effect via the electric traction motor during electric emergency braking. Figure 4 In the example, the Figure 3The electric traction motor has power data (130 kW, 250 Nm, transmission ratio 9.5) and a torque gradient of 15000 Nm / s. In the electrohydraulic EHB system, a black-white brake circuit allocation is used, that is, a brake circuit for the front axle of the vehicle and a second brake circuit for the rear axle of the vehicle. Curve BM TM1-VA and BM TM2-HA The braking torque increase of the electric traction motor at the front axle VA or rear axle HA is shown, in particular with a braking torque gradient of 15000 Nm / s. This increase is taken into account for the electronic brake force distribution EBV, so that, as in Figures 6a to 6d It is further explained that the pressure profile of the advantageous hydraulic brake system is distributed to the front and rear axles so that the front and rear axles simultaneously reach their maximum braking torque, for example for a 1 g deceleration, while at the same time ensuring that the design priorities are taken into account (see table 1 of priorities).

[0241] In a simplified representation, the braking torque increases further after reaching the maximum braking torque (illustrated in the figure at, for example, 1 g) in order to illustrate a further braking torque profile over time and thus also the TTL for a higher deceleration (e.g. to 1.4 g for a sports vehicle). If an ABS situation occurs, typically at a deceleration of, for example, 1 g, the braking torque is sequentially reduced and followed by an ABS control operation, as described below with reference to Figure 5 , Figure 5a , Figure 5b , Figure 5c Further clarification.

[0242] Curve BM EHB-HA Here, the braking torque curve of the electrohydraulic brake for the rear axle is shown; curve BM HA,EHB+TM2-HA The sum of the braking torque curves of the electrohydraulic brakes for the rear axle and of the traction motor TM2 associated with the rear axle is shown.

[0243] In addition, the curve BM EHB-VA The curve BM shows the braking torque variation curve of the electrohydraulic brake for the front axle; VA,EHB+TM1-VA The sum of the braking torque curves of the electrohydraulic brakes for the front axle and the traction motor is shown.

[0244] As the upper horizontal line BLM-VA, the braking torque corresponding to the locking pressure for the front axle VA is plotted. As the lower horizontal line BLM-HA, the braking torque corresponding to the locking pressure for the rear axle HA is plotted.

[0245] The corresponding locking pressure is obtained at the point where the curve for the braking torque achieved by means of the brake units EHB-VA, TM1, EHB-HA, TM2 intersects the horizontal line BLM-VA, BLM-HA. The time until this point is reached is indicated as Time-to-Lock (TTL).

[0246] The TTL for the electrohydraulic brakes EHB-VA, EHB-HA alone is approximately 140 ms, whereas it is approximately 90 ms when the regenerative braking torque of the traction motors TM1, TM2 is additionally used. This means that the TTL can be reduced from 140 ms to 95 ms by the difference ΔT in the simulation by means of the control of the driving dynamics system, which has a significant effect on the braking distance. At a speed of 100 km / h, for example, these 45 ms correspond to a distance traveled of approximately 1 meter. This is already a significant improvement compared to the typical braking distance of 25 m with ABS braking.

[0247] This 1m improvement in braking distance is a very challenging goal for applications using ABS braking systems.

[0248] Figure 5 A further basic concept of the coordinated use of the braking torque of the electric traction motor and of the electrohydraulic brake unit is illustrated by means of a typical ABS control curve at high pressures on asphalt roads, ie in so-called “high μ situations”.

[0249] Since, as already explained above, traction motors are able to build up and release braking torque very quickly, the use of electric traction motors in ABS control is unproblematic.

[0250] exist Figure 5 A curve for the deceleration of the vehicle is shown in , and curves for the wheel speeds of the four wheels of the vehicle are also shown.

[0251] Advantageously, in ABS operation, the electric traction motor generates a basic braking torque VA, which Figure 5 An exemplary arrangement of an electric traction motor at the front axle is shown in FIG. This results in that the pre-pressure of the electrohydraulic brake unit EHB can be reduced to the basic braking torque of the electric traction motor. This results in that, as in Figure 4 It is explained that locking pressure can be generated quickly and the EHB pressure required for ABS regulation can be reduced.

[0252] This can be used to streamline the brake system, which usually has to generate a pre-pressure of 20% to 40% higher than the maximum wheel pressure. However, if 50% of the basic braking torque is generated via the electric traction motor, then instead of the typical design for 120 bar to 140 bar, only 70 bar to 80 bar pressure is required for ABS operation. In addition, in the case of regenerative braking (see above reference Figure 3 After the temperature rise of the brake system is significantly reduced by the implementation scheme of the brake system, the EHB design for 100 bar is sufficient for safe regulation operation.

[0253] exist Figure 5 , how the basic braking torque is provided by the electric traction motor at the front axle VA. The difference ΔP from the desired pre-pressure for the front axle VA is then relatively small. The pressure regulation for the two wheels of the front axle VA has correspondingly a small-amplitude variation, so that the electrohydraulic brake unit can be designed smaller.

[0254] This has a significant impact on the brake system, since on the one hand the pressure supply requires a smaller volume in order to provide the required fluid volume, and the electric motor of the electrohydraulic brake unit EHB can only generate 50% of the braking torque. In addition, the valve design of the hydraulic control unit HCU of the EHB can be adapted by using smaller or more cost-effective valves that can be designed for a significantly lower pressure resistance. The basic concept described can reduce the costs of the EHB by about 10%. In addition, the friction brake can be implemented significantly more cost-effectively, since the thermal load must be reduced and a lower braking torque must be transmitted to the brake pad. In the case of sports vehicles, expensive ceramic brakes can be replaced by significantly cost-effective grey cast iron brakes.

[0255] exist Figure 5a and 5b The figure shows the hysteresis of the ABS control with an electric traction motor relative to a standard ABS system. For this purpose, a comparative diagram illustrates the time course of the wheel speed of the wheel vR1.

[0256] Figure 5a The typical sequence at the beginning of a regulation cycle of pressure relief in ABS operation with a standard ESP system or a one-box system is shown for low coefficients of friction, for example on snow.

[0257] In the upper diagram, the wheel speed is plotted as a function of time t. In the lower diagram, the pressure is plotted as a function of time t (upper curve); in addition, the opening state of the valve is schematically shown over time t (lower curve).

[0258] After a time t0 due to the dead time of the system, the wheel locks, since the wheel speed v is equal to the reference speed vref After that, the outlet valve is opened for pressure release. Until the valve is opened, time t VM During this time period, the wheel speed continues to decrease by Δv1. Then, after the valve opening phase, a valve opening is performed for a duration of t ab The pressure is released, which is shown in simplified linear form. During this time period, the wheel speed continues to drop by Δv2 until the wheel stabilizes. The valve is then closed again. This is followed by a stepwise pressure build-up (not shown) in order to bring the wheel speed back to the reference speed v ref This is preferably done via a small, step-by-step pressure increase via the inlet valve at the level of the inlet.

[0259] Figure 5b Wheel ABS regulation via the traction motor is shown.

[0260] In the upper diagram, the wheel speed is plotted against the time t. In the lower diagram, the pressure is plotted against the time t.

[0261] If, in the ABS control described here with the traction motor, it is preferred to use a central control unit M-ECU with high resolution. 域 Wheel speed sensors with short delay times in data transmission can detect ABS situations characterized by wheel speed deviations from reference values ​​more quickly, especially due to the precise modeling of the vehicle model in the central computer. The delay time t0 is therefore shorter in the control of the driving dynamics system according to the invention, and the speed difference Δv is also smaller. In addition, since no valves are required in the ABS control with electric traction motors and the time lag of the torque change is negligibly small in the inverter of a high-power traction motor, the ABS can be controlled more quickly, especially in the case of larger braking torque gradients (see Fig.12 ) for low road friction coefficients without additional time lag t MV In the case of a braking torque release, the braking torque is released immediately after the start of deceleration t0. In addition, due to the higher resolution, an improved wheel acceleration control using the central control can be achieved, so that the desired wheel torque can be reached faster and also without overshoot. If this is followed by a deceleration, which also does not involve valve actuation, and in addition has a braking torque increase with the precision of the motor control using a torque and motor speed control cascade (in particular, therefore taking into account the torque / current of the electric motor of the pressure regulator, the position of the piston in the piston-cylinder system of the pressure regulator, and the actuation speed, i.e. the speed of adjustment of the piston of the pressure regulator), the reference speed v is reached again without fluctuations in the braking torque curve and also significantly faster. refDue to the lower deviation of the reference speed, the braking distance can be reduced in the ABS when controlling with an electric traction motor compared to a standard ABS system, at the same time as lower noise due to the low pressure fluctuations. From a different perspective, the same control quality can be achieved with a smaller braking torque gradient when controlling with the aid of a traction motor compared to the braking torque gradient of an electrohydraulic brake unit EHB, since the critical time lag t caused by the solenoid valve is omitted. vM Furthermore, the reaction time t0 can be reduced by a high-performance computer and by wheel speed sensors with a higher resolution, ie wheel locking can be detected earlier and corrective actions can be taken more quickly.

[0262] Figure 5c Further advantages according to the invention of the common braking torque modulation are shown in the control mode by way of example for a negative μ-Sprung, ie when the vehicle is driving from asphalt onto snow, for example.

[0263] exist Figure 5c In , the pressure or the corresponding braking torque at the front axle VA and at the rear axle HA is plotted as a function of time t. Here, the curves of the braking torque generated at the front axle and the rear axle by means of the traction motor and the total braking torque at the front axle and the rear axle are shown.

[0264] exist Figure 5c In the simplified example, it is assumed that the two wheels of the front axle have the same braking torque or the same brake pressure and that both the front axle and the rear axle have traction motors at the axles which contribute the basic braking torque to the total braking torque of the respective axle. brems,ges,Vrad or M brems,ges,Hrad , the braking torque of the traction motor M brems,TM,Vrad or M brems,TM,Hrad The hydraulic braking torque (not shown) of the electrohydraulic brake unit EHB of the front or rear wheels acts cumulatively. When releasing the braking torque, the braking torque M of the front axle can be released first without a time delay. brems,TM,Vrad , then, with the above-mentioned time lag t0, the pressure is released by the EHB. As a result, as soon as the EHB can release the pressure, the braking torque can be adapted very quickly and the gradient can be increased. This has a positive effect on the speed reduction of the front wheels, which is not shown. With a short time deceleration, the braking torque at the rear axle or the braking torque M brems,ges,Hrad release, which—as described above for the front axle—is initiated quickly by the electric traction motor without further time delay t0. brems,TM,Hrad benefited from it, so that the speed did not drop so sharply in this round.

[0265] Figure 5dThe approach according to the invention is shown for another control situation in which the vehicle is driven on a largely uniform road surface, for example a road surface with snow (so-called low μ situation).

[0266] Plot the braking torque M generated at the wheels, namely the right front wheel VR, the left front wheel VL, the right rear wheel HR and the right front wheel VR, in relation to time t. brems .

[0267] In this case, the front axle is advantageously controlled by means of the EHB, while a lower braking torque is obtained for the rear axle via the two traction motors TM1 and TM2, wherein the braking torque is explained below. Figure 6b or Figure 6d Based on the conception of.

[0268] Alternatively, the regulation can also be transferred to the drive concept, whereby at the rear axle Figure 6c The concept is provided with an electromechanical brake unit EMB and an electrohydraulic brake unit EHB at the front axle. The electric brake unit EMB has similar advantages to the traction motor, such as precise braking torque regulation and high braking torque gradients through torque regulation and acceleration regulation of the motor of the EMB. The electric brake EMB even outperforms the electric traction motor in the braking torque gradient (see Fig.12 In addition, the brake pad tensioning effect of the EMB is eliminated at low friction coefficients.

[0269] Figure 6a A hydraulic brake system is shown which is advantageous for connection to a driving dynamics system according to a first embodiment (“Architecture I”), which is used for four wheel brakes and has an electric traction motor TM1 at the rear axle of the vehicle and an electric traction motor TM2 at the front axle of the vehicle. In addition, the brake system can have a redundant pressure supply mechanism in the form of a piston-cylinder unit driven via an electric motor and a spindle drive. The pressure supply mechanism can be equipped with a current sensor i / U and an angle sensor a / U and optionally with a temperature sensor T / U for measuring the motor temperature of the EC motor. In addition, the piston-cylinder unit can have redundant phase connections, redundant electronic devices and / or redundant vehicle power supply connections BN1 and BN2 and a chassis-domain (M-ECU) for connection to a central controller. 底盘域 ) data lines DS1 and DS2 for communication. The brake system can also have an electric pedal with a sensor ECU and a sensor, in particular a force-travel sensor for detecting the pedal force based on the differential measurement principle (see US 13 / 883,192) transferred to the electric pedal concept. The sensor ECU can communicate with a central controller in the chassis domain.

[0270] Furthermore, it is possible to use a double-acting specific inlet / outlet valve (represented in simplified form as MV 2k ), wherein pressure can be built up or released by simultaneous advancement and retraction of the piston of the piston-cylinder unit. Alternatively, different connections of the valve can be provided, so that the cross section of the valve can be controlled by suitable energization either during pressure buildup or during pressure release. If, for example, the valve seat is connected to the wheel brake, different pressure gradients can be achieved during pressure release, so that pressure in multiple wheel brakes can be released simultaneously and with little noise. The pressure buildup then takes place simultaneously or in multiplexed fashion via the pressure supply unit via volume control.

[0271] If the valve seat is connected to the pressure supply mechanism, the pressure is built up via a classic pre-pressure control. For the latter method, outlet valves AV1-AV4 are advantageous, but are not mandatorily provided for pressure release. In addition, it is meaningful to use the outlet valves only in extreme cases, since the volume of the pressure supply mechanism is thereby lost in the storage container; in the case of relatively long regulation interventions, it is then necessary to withdraw the volume from the storage container by retracting the piston, see the regulation strategy according to EP 2580095B1. Therefore, the amount of volume released via the outlet valve should be set so that in order to avoid critical regulation interruptions, the braking process can be completely terminated and re-delivery is only necessary after the braking process has ended. Alternatively, the pressure supply mechanism can also be provided with a two-way piston for continuous delivery, as described in EP 3 145 771 B1, or the electric traction motor can take over the braking torque regulation during the interrupted time period.

[0272] This system solution has an inlet / outlet valve MV 2k Or the degree of freedom of optional pressure release via outlet valves. The use of outlet valves is therefore optional and 1 to 4 outlet valves can be selectively provided. The outlet valves here provide only one additional degree of freedom in the possibility of pressure release. It is meaningful to provide all wheels with outlet valves when the system is introduced, wherein the number of outlet valves is then gradually reduced during product maintenance.

[0273] Alternatively, the known multiplexing method at two wheel brakes can also be combined with a classic pressure control via inlet / outlet valves at two further wheel brakes. In this case, standard inlet valves or MV 2k The valve is used only for pressure build-up and pressure relief in the operation of the brake booster. In addition, the electric traction motor can be advantageously simplified (see Figure 5 ) for realizing an efficient masking strategy, wherein the electric traction motor can provide a basic braking torque in ABS operation and / or in the emergency braking function AEB (see Figure 4 ) is used to achieve faster TTL.

[0274] Furthermore, a targeted braking torque intervention is advantageously predefined via the domain as a desired value or desired value profile, which advantageously also determines the temporal profile of the braking torque increase or braking torque reduction in order to enable efficient synchronization with the braking torque profile of the electric traction motor. The intervention can be performed axle-individually or wheel-individually. The wheel-individual intervention is primarily used for yaw torque control, for example for torque vectoring intervention, which is advantageously also synchronized in time with the steering intervention of the electric servo steering EPS.

[0275] In addition, using MV 2k - The valve has the advantage of being able to diagnose failures in the turbine circuit and to be able to close the MV in the event of a fault 2k Thus, even in the event of a failure of the wheel circuit, a three-channel control operation is still possible, which can be used for ABS control, but also for yaw torque intervention for steering support or emergency steering in the event of a failure or partial failure of the electric servo steering.

[0276] Furthermore, the brake units are preferably designed redundantly, for example with redundant windings and electronics, so that the individual brake units can still operate even in the event of a partial failure. This allows double to triple redundancy of the brake function with high reliability. Even when the braking power is reduced, critical situations can still be controlled. If the pressure supply fails partially, 50% of the maximum braking torque can still be established with the reduced dynamics of 1×3 phases instead of 2×3 phases, that is to say approximately 70 bar in the design for 140 bar. This allows full ABS operation up to the locking pressure at both axles, since the electric traction motor can then provide a supporting torque at one or both axles.

[0277] The hydraulic brake system with the driving dynamics system described here has a very simple and cost-effective construction (few solenoid valves, reduced pressure supply) and meets all redundancy requirements of SAE Class 4, as explained above.

[0278] Figure 6b A second embodiment of an electrohydraulic brake unit EHB is shown, which has two electric traction motors TM1 and TM2 at the rear axle and one traction motor TM3 at the front axle. The traction motor TM3 can be omitted, wherein the two traction motors TM1 and TM2 are system-relevant and represent the plug-in Figure 2 Topology B.

[0279] From the pressure supply of the electrohydraulic brake unit EHB, only one hydraulic line leads to the two wheel brakes RB3 and RB4 of the rear axle, and only one cost-effective drum brake is advantageously used at the rear axle.

[0280] The electric traction motors TM1 and TM2 have a high power of more than 50 kW per wheel. The braking torque build-up and braking torque release are carried out dynamically. The traction motors TM1 and TM2 take over the braking torque regulation, while the EHB is only used to apply the basic braking torque for the rear axle in normal operation.

[0281] Adjust operation and Figure 5 The situation shown in FIG. 1 is similar, with the difference that the roles of the EHB and the traction motor are swapped and this time the EHB instead of the electric traction motor establishes the basic braking torque. On the front axle, on the other hand, the ABS control is performed via the EHB and the optional traction motor TM3 provides the basic braking torque. If the optional traction motor TM3 is used at the front axle, cost-effective drum brakes can also be used here.

[0282] In the first fault case, for example, if the hydraulic connection to the wheel brakes of the rear axle fails, the connection line is disconnected via the isolating valve and the traction motor completely takes over the control function there. Due to the power and speed of the traction motor, the deceleration of the rear axle is limited if necessary, but all safety-critical functions (μ-Sprung, ABS for low μ) can nevertheless be controlled very safely and steerability (priority level 3) is ensured by front axle pressure control and / or by actuation of the steering EPB via the driving dynamics system.

[0283] The speed of the vehicle is meaningfully limited in such a fault situation (for example in accordance with Figure 3 The fault case leads to a longer braking distance without speed limitation, but is otherwise not critical from a safety perspective.

[0284] If the electric traction motors TM1 and TM2 of the rear axle fail in the second fault situation, the ABS is axle-controlled via the pressure supply. Steering intervention is then preferably performed by the driving dynamics system via the activation of the EPS. If only one traction motor fails, steering intervention can also be performed via the still functioning traction motor.

[0285] Even in the event of a partial failure of the pressure supply, for example in the event of a winding failure of the electric motor, pressure regulation can still be maintained, albeit at a lower power, by taking over the second branch of the 2×3 phase with a regulation of 50% of the power. In this case, the traction motor at the rear axle can also take over anti-slip regulation (ASR) and torque vectoring or yaw torque intervention.

[0286] according to Figure 6b The embodiment of the hydraulic brake system is again better than in Figure 6aThe system shown in is simpler because fewer solenoid valves and hydraulic lines are provided and drum brakes can be used. Figure 6b The embodiments of also meet the redundancy requirements of SAE Level 4, as described above.

[0287] Figure 6c A third embodiment is shown with two electromechanical brakes EMB1 and EMB2 at the rear axle and one traction motor TM3 at the front axle.

[0288] The traction motor TM3 can be omitted, but the electric brake units EMB1 and EMB2 are important for the system and represent the plug-in Figure 2 Topology B and topology D. From the pressure supply mechanism of the EHB, only one hydraulic line leads to the two wheel brakes RB3 and RB4 of the rear axle. In particular, only cost-effective drum brakes can be used at the rear axle.

[0289] The electromechanical brake units EMB1 and EMB2 dynamically implement the braking torque build-up and braking torque release and take over the braking torque control in the process. The electrohydraulic brake EHB is used only to apply the basic braking torque for the rear axle in normal operation. The control operation is similar to the above-mentioned reference Figure 5 The explanation proceeds similarly, but with the difference that the effects of EHB and EMB are swapped and the EHB establishes the basic braking torque. On the front axle, on the other hand, the ABS control is performed via the EHB and the optional traction motor TM3 provides the basic braking torque. If the optional traction motor TM3 is used at the front axle, a cost-effective drum brake can also be used here.

[0290] In the first fault case, for example, when the hydraulic connection to the wheel brakes of the rear axle fails, the connection line is disconnected via the isolating valve and EMB1 and EMB2 completely take over the control functions at the individual wheels of the rear axle. This allows all safety-critical functions (μ-Sprung, ABS for low μ) to be controlled very safely by the EMB even without hydraulic support and steerability (priority level 3) is ensured by front axle pressure control and / or by actuation of the steering EPB via the driving dynamics system.

[0291] The electromechanical brake units EMB1 and EMB2 are sensibly designed for a locking brake torque with a small reserve for attenuation (20% reserve); the electromechanical brake units EMB1, EMB2 can also be advantageously designed for a braking torque below the locking limit (approximately 50% of the locking brake torque) for cost reasons. In normal operation, the braking torque for regulation can be safely achieved at maximum deceleration by means of EHB support without subjecting the drum brake to severe thermal loads. In the event of a hydraulic line failure, it is entirely acceptable that the rear axle can contribute less braking torque for overall deceleration than the front axle, since the effect on the extension of the braking distance is minimal. It is important that the regulating operation at low μ and μ-Sprung is dominant. Here, 50% of the locking torque is sufficient for safe driving operation.

[0292] If the electromechanical brake units EMB1 and EMB2 of the rear axle fail in the second fault situation, the ABS is axle-controlled via the pressure supply. A steering intervention is then preferably performed by the driving dynamics system via the activation of the EPS. If only one electromechanical brake unit EMB (EMB1 or EMB2) fails, a steering intervention can also be performed via the still active electromechanical brake unit EMB (EMB2 or EMB1).

[0293] Even in the event of a partial failure of the pressure supply, for example in the event of a winding failure of the electric motor, pressure regulation can still be maintained, albeit with reduced power, by the second branch of the 2×3 phase taking over the regulation of 50% of the torque. In addition, the electromechanical brake units EMB1 and EMB2 at the rear axle take over the anti-slip control (ASR) as well as the torque vectoring and / or yaw torque intervention.

[0294] according to Figure 6c The embodiment of the hydraulic brake system is Figure 6a The system shown in is simpler because fewer solenoid valves and hydraulic lines are provided and drum brakes can be used. Figure 6c The embodiments of also meet the redundancy requirements of SAE Level 4, as described above.

[0295] This solution is useful in situations where no electric traction motor is provided at the rear axle or neither at the rear axle nor at the front axle for intervention in generating a braking torque by means of the driving dynamics system, for example in hydrogen vehicles or hybrid vehicles, in which the electric motor is closely coupled to the internal combustion engine and is therefore not dynamic.

[0296] Figure 6d A fourth variant of an electrohydraulic brake unit EHB for integration into the vehicle dynamics system is shown, wherein only one electrohydraulic brake is provided for the front axle and, as already described, at the rear axle. Figure 6b As in the example, electric traction motors TM1 and TM2 are also provided for each wheel.

[0297] and Figure 6b Unlike the system of the traction motor, the rear axle is not supported by the basic braking torque via the EHB, that is, the traction motor is advantageously implemented with relatively higher power and can apply and dynamically adjust the braking torque up to the locking limit. This configuration is advantageous in sports cars or luxury vehicles with strong motorization, because the motor is strong enough and an electrohydraulic brake unit EHB for the rear axle is no longer required. In this arrangement, the friction brake is completely eliminated at the rear axle. The traction motors TM1 and TM2 take over multiple functions (ESP intervention, ASR intervention, ABS intervention, EBV brake torque regulation) and are controlled synchronously in time with the electrohydraulic brake unit EHB of the front axle via the driving dynamics system, that is, the brake torque target value is also synchronized with the change in time.

[0298] Figure 7a Two curves showing a motor torque-speed characteristic curve family, scaled with the transmission ratio for the speed of a vehicle weighing 1800 kg up to a maximum speed of 200 km / h, thus showing a motor torque-vehicle speed characteristic curve family. For 1 g=9.81 m / s 2 The braking torque for the deceleration is calculated with a weight distribution VA / HA of 65% / 35% and is shown as a dashed line for the braking torque of the front axle (upper horizontal line, dashed line) and the braking torque of the rear axle (lower horizontal line, dashed line). Figure 7a In the example denoted as "Mbrems_normal" in Figure 1, the typical design of a motor with a typical inverter is based on the typical design of the motor, since the electric traction motor is designed for constant power and is therefore primarily limited by the voltage from a certain point P1 of the power hyperbola. Also up to speed v2, a maximum braking torque can be generated at the rear axle by the electric traction motor in generator mode.

[0299] In order to be able to optimally utilize the braking torque of the traction motor for braking even at maximum speed, an inverter can advantageously be used, which enables the coils to be switched from a series connection of the coil windings to a parallel connection. This divides the inductance by half and, with the given voltage, a higher torque can be generated at the same speed; at the same time, the torque dynamics are also increased by 100%, which is very advantageous for highly dynamic braking torque control in ABS operation. In addition, the inverter should be designed in such a way that, similar to the 2×3-phase converter concept, operation is still possible even when one or more components (power semiconductors, coil windings) fail, in order to prevent a complete failure of the electric traction motor as a brake unit.

[0300] In other exemplary embodiments, other topologies known from the prior art and similar in function can also be used to achieve the functionalities required above. However, these usually have between 24 and more than 42 switching elements in order to achieve redundancy (2×3 phases) and the ability to switch between series and parallel connection during operation. These switching elements can also be used for the boost function.

[0301] Figure 7b A converter is shown which, in contrast to similar systems in the prior art, has only 18 switching elements instead of 30 to more than 40 switching elements and which, like a standard converter also for brushless motors, can also be operated in four-quadrant operation. The four quadrants result from positive or negative torque and positive or negative speed. Four-quadrant operation on the one hand A motor torque-assist operating mode is possible, in which the torque is temporarily increased by up to 100%, on the other hand This results in redundancy in the event of failure of one or more components (circuit breakers, coil windings).

[0302] A converter having the possibilities described above is always more complex than a three-phase standard converter, which typically has six switching elements, primarily due to the complexity in terms of wiring and components. Application for the vehicle dynamics system described here is particularly attractive in the following cases: Figure 6c In normal braking operation and in ABS control operation, only regenerative braking of the rear axle is possible, thereby achieving potentially significant cost and weight savings by omitting the friction brake. In addition, although redundancy of the converter is not absolutely necessary for SAE Class 2, it meets the requirements for SAE Class 3, since even in the event of a partial failure of the electric traction motor, control operation continues to be possible at the rear axle. SAE Class 3 also alternatively demonstrates that the inverter concept with 30 to 40 components according to the prior art is appropriate, since similar brake systems, for example two-box brake systems, are again significantly more complex than typical single-box brake systems for SAE Class 2.

[0303] The configuration of the novel converter according to the invention (designated as "RSP-4Q converter") described in detail below enables a converter with only 18 switching elements (a total of only six connecting switching elements and twelve supply switching elements) to be realized, which allows, during operation of the electric motor, a change from a series connection of the phases to a parallel connection of the phases and vice versa. In the parallel connection, twelve supply switching elements are activated, while in the series connection, six connecting switching elements and six of the twelve supply switching elements are activated. "Activation" here can be understood to mean that the switching elements are actuated in a clocked manner, while the other switching elements are, for example, in idle operation.

[0304] In addition, switching from series connection to parallel connection or vice versa is performed according to the failure of one or more operating elements. The operating elements can be understood to include but are not limited to switching elements, such as power supply switching elements and connecting switching elements, and / or coils of each phase. Through the design, it is possible in a simple manner to continue to operate the motor by switching from series connection to parallel connection when one or more operating elements fail.

[0305] exist Figure 7b The converter shown in , as described, for example, in WO 2021 / 179980, is connected to an electric motor 4 having six phases U, V, W, U′, V′, W′, which is depicted merely schematically with a circle and its connections.

[0306] Each phase U, V, W, U', V', W' has at least one coil 6. Two phases U, V, W, U', V', W' are combined into a branch line. Figure 7b 8 is shown by way of example by means of loops of the phases that respectively constitute the branch line. Each of the two phases U, V, W, U', V', W' of the branch line is electrically rotated 180 degrees relative to the other phase U, V, W, U', V', W' of the same branch line 8, i.e., is connected in reverse. The difference of the respectively reversely connected phases U', V', W' relative to the other phases U, V, W is indicated by a dotted line. Therefore, in the embodiment, phase U' is a phase reversely connected relative to U, phase V' is a phase reversed relative to phase V, and phase W' is a phase reversed relative to phase W.

[0307] The converter also has six switching units 10, which are indicated by dashed boxes. One switching unit 10 is associated with each phase U, V, W, U', V', W'. In addition, the switching units 10 of two phases U, V, W, U', V', W' of a branch each form a switching module. In the figure, the switching units 10 each form a switching module, so that according to Figure 7b The converter according to the present invention has three switching modules. Each switching unit 10 is connected to an element that applies a supply voltage to each phase U, V, W, U', V', W'. For this purpose, each switching unit 10 has two power supply switching elements 16. The power supply switching element 16 is configured as a MOSFET in the embodiment.

[0308] Depending on the operating mode of the electric motor 4 , two phases U, V, W, U′, V′, W′ of a branch are connected in parallel or in series. For this purpose, the converter 2 has a control unit which is configured to actuate the supply switching element 16 and the connecting switching element 20 .

[0309] In addition, the converter 2 has a safety unit (in Figure 7bThe safety unit is also denoted as a "breaker module" and is arranged between the motor 4 and the converter 2. The safety unit has a switching element (not shown) which is configured to preferably galvanically separate the motor 4 from the converter 2 in the event of a fault.

[0310] For reasons of simplicity, the RSP-4Q inverter described here is used for a control strategy with torque boost, as in Figure 7a However, in other embodiments, another inverter that enables switching of the inductance during operation may also be suitable, such as, for example, an inverter with switching between delta connection and star connection or another inverter, as is used, for example, in DE 11 2018 000 733 T5 or DE 11 2018 001 213 T.

[0311] Figure 8 A normally open inlet-outlet valve MV is shown which functions in both directions. 2k In an advantageous embodiment, the inlet-outlet valve is used to achieve Figure 6a To Figure Figure 6d The pressure regulation function in the EHB brake system or for Figure 9a and 9b Axle pressure regulator.

[0312] Figure 8 The specific valve MV required for the described embodiment is shown. 2k , the valve works safely in both flow directions. That is, even in the case of large flow rates, such as 100 cm 3 / s to 120cm 3 / s, or at large pressure differences across the valve, such as, for example, 160 bar to 220 bar, the functionality of the valve is also ensured. In particular, for the previously described ranges of the parameters in the valve MV 2k Make sure the valve does not close automatically.

[0313] Valve MV 2k In principle, it has a typical structure of a solenoid valve, which has a solenoid circuit EM1 with an armature 6, a valve actuator or valve tappet 7 and a valve seat 8 as well as a return spring 13. Figure 8 If the force addition device formed by the electromagnetic circuit EM2 is correspondingly configured, the return spring can be discarded.

[0314] The magnetic circuit EM1 is generated over the travel h (see Figure 8a ) Strong progressive force curve FM1 and the return spring 13 generates a progressive return force F over the stroke h RF Used to reset the armature.

[0315] Armature 6 Figure 8 The left part of the figure is coupled to a second force generating element, which forms a force adding device. The force adding device can be formed by a second electromagnetic circuit EM2 with an armature 6a, the switchable force F of the second electromagnetic circuit M2 The force F of the first magnetic circuit EM1 M1 Opposite effect.

[0316] As a more cost-effective alternative, a permanent magnet circuit can also be used as a passive force application device, which comprises a small permanent magnet 9 with a pole plate 10 .

[0317] F M2 The force and F M1 On the contrary, and in the case of an open valve, a relatively strong force acts with a strong desired drop in force over the travel h.

[0318] Force F M2 (See Figure 8b ) is always still large enough when the stroke end is reached to take over the usual armature return and thus optionally also replace the usual return spring 13.

[0319] Figure 8c The force source F is shown as a function of the current intensity M1 and F in the case of permanent magnets M2 The joint effect.

[0320] At the valve seat, in the closed valve position, if the pressure P2 is greater than the pressure P1 , the pressure difference P2 − P1 acts with a force FP directed in the direction of valve opening.

[0321] At the valve seat, in the open valve position, the described hydraulic pressure F can pull the valve open due to the volume flow Q through the valve without countermeasures. H Not only in the pressure build-up P auf When and also release the pressure P ab When the solenoid valve MV 2k How it is connected to the pressure supply DV and the wheel brake cylinders and how it works depending on the direction of the volume flow. This is the following Figure 9a and Figure 9b The basis for pressure regulation with a pressure supply device and a wheel brake is shown in FIG.

[0322] If the solenoid valve is in the open position, the force F H The Bernoulli effect acts according to the height of the volume flow Q. If the volume flow Q is very high, for example at high pressure differences, this can cause the valve to be closed only by the flow force FH This causes the valve to be closed and no longer able to be opened.

[0323] In order to avoid the above effect, the force F of the force application device M2 with force F H The opposite occurs and prevents the valve from closing even at large pressure differences that can occur during operation of the brake system.

[0324] Preferably, the additional force F M It is highest in the open position of the valve, which can be achieved, for example, by a permanent magnet circuit and acts over the entire stroke range and supports the restoring force F of the valve spring. RF , so that the valve is always returned to the open valve position when a volume flow Q flows through it, regardless of the valve position, ie, in particular also in the semi-closed state.

[0325] In a corresponding embodiment, the valve restoring spring 13 can also be omitted.

[0326] The valve must also be designed so that when the valve is energized by activating the magnetic circuit EM1, the main valve force F M1 Able to overcome two forces (F M2 +F RF ) so that the valve can be closed when power is turned on.

[0327] Large volume flows can occur, for example, in the case of wheel brakes, as is typical in wheel valve arrangements with inlet / outlet valves (for the described embodiments see Figure 6a-6d ), connected to the switching valve via the armature connection and the current supply to the ECU or the brake system fails at this moment, thereby preventing the pressure release via the outlet valve, because the outlet valve can be closed by the differential pressure and can no longer be opened because it is greater than the restoring force F of the valve spring. RF The remaining residual pressure blocks the valve. Valve tensioning can also occur when the wheel brake pressure is released with a very high pressure gradient, for example when the pressure is released by a very fast return movement of the piston of the pressure supply unit.

[0328] The normally open valve design is also important when the pressure supply is connected to the armature connection, see e.g. Figure 9a and Figure 9b , and very quickly build up pressure with the pressure supply unit. A fast pressure build-up is performed, for example, in automatic emergency braking (AEB) or in a multiplex method with a pressure change control via volume control / control of the pressure supply device instead of a pressure change control via a PWM-controlled volume flow throttling control of the inlet valve and a pre-pressure control.

[0329] The tensioning effect can be defined by a pressure difference in the regulation of the pressure supply unit or preferably by means of a throttle valve (not shown in the figures), wherein the throttle valve is arranged in the hydraulic line upstream of the armature connection of the valve connection.

[0330] Furthermore, it is alternatively conceivable to arrange a pressure relief valve hydraulically in parallel with the switching valve, which pressure relief valve opens at high differential pressures and thus limits the hydraulic pressure F acting by the Bernoulli effect. H , so no force addition device F is required M2 This simplifies the valve design, but limits the pressure dynamics via the hydraulic pressure supply.

[0331] If the braking torque change is regulated in parallel via the traction motor, such measures are not required, since the dynamic requirements on the hydraulic brake system are lower. Standard valves can then be used without the use of additional force devices and throttle valves or pressure relief valves.

[0332] In the event of a wheel circuit failure, the wheel circuit can be disconnected by closing the inlet valve SV arranged between the wheel brake and the pressure supply mechanism. Thus, a hydraulic brake system with n wheel circuits can be operated with one less wheel circuit, that is to say with n-1 wheel circuits. Thus, it is possible, for example, to replace a four-circuit brake system regulation with three circuits. Thus, after closing the inlet valve SV, in the event of a wheel circuit failure, a very high deceleration can always be achieved, and the yaw torque regulation or ESP function with three wheel brakes can also be maintained. The electric motor is available at the failed wheel circuit, which can then take over the brake torque regulation of the failed wheel brake so that the four-circuit brake torque regulation can continue to be maintained without or with only a few restrictions, for example, by the maximum brake torque of the traction motor.

[0333] The valve tappet 7 can also have a specific shape which provides a counteracting force by the hydraulic flow force and can reduce the tensioning force.

[0334] Figure 8c The electrical actuation of the valve via the current i is shown. The current intensity i1 is selected in the closed valve position such that F M1 Greater than F M2 In the closed position of the valve, the current can then be varied at current intensity i2 as a function of the hydraulic differential pressure P2-P1 across the valve. M2 For the reasons mentioned, in this position the valve is within the range of the usual spring forces, so that it can also be operated, for example, with current control or current regulation.

[0335] To keep the valve in the closed position, the differential force

[0336] F V,zu =FM1,zu -F M2,zu

[0337] It must be greater than the force FP resulting from the differential pressure P2 - P1 across the valve in the closed position.

[0338] Figure 9a The construction of a pressure regulator in the form of a piston-cylinder unit driven by an electric motor via a transmission is described, to which two wheel brakes R1 and R2 and optionally a further hydraulic consumer Vx are connected via hydraulic lines. The further hydraulic consumer Vx can be a further wheel brake or also a further hydraulic consumer, for example a hydraulic piston of a clutch (or clutches) or a further servo piston of a hydraulic servo steering or a vehicle axle. Preferably, the pressure regulator is also connected to a valve arrangement having a reservoir VB.

[0339] The pressure regulator is preferably for both controllers ECU1 EHB and ECU2 EHB In each case there are 2×3 phase connections, in which current sensors i / U and angle sensors α / U are provided, which are preferably also designed redundantly and which serve for high-precision PPC pressure control or pressure regulation via piston position or current.

[0340] At the outlet of the pressure supply, a pressure sensor p / U is preferably provided, which is mainly used for calibration purposes. However, pressure regulation or pressure control can also be performed without the pressure sensor, when a relationship between the EHB braking torque and the current or piston position is additionally established, for example by using an acceleration sensor or by balancing the vehicle deceleration by means of the braking torque or by means of the braking torque of the electric traction motors TM1-TM4.

[0341] A bidirectional inlet / outlet valve, designated here as "MV 2k -". Here, MV 2k The valve is operated so that both pressure build-up and pressure relief are possible via the solenoid valve, wherein the pressure change is particularly highly dynamic, ie with >1000 bar / s, preferably >2000 bar / s. The valve must be designed to be normally open according to the system specifications, ie according to the required maximum pressure and maximum volume flow.

[0342] Preferably, the method according to Figure 8 to Figure 8c Solenoid valve with a first soft ferromagnetic circuit EM1 and a second permanent magnet circuit EM2.

[0343] Alternatively, it is also possible to use a modified inlet valve of a standard ESP unit as MV2k , that is to say a solenoid valve that opens without current, without a second permanent magnet circuit EM2, with a standard valve opening cross section and an armature diameter of 6 mm, which can also be implemented as normally open in a classic design, in particular due to the lower maximum pressure occurring in current driving dynamics systems and therefore lower tensioning forces in the case of pressure changes with maximum pressure gradients.

[0344] If the inlet valve of the ABS / ESP unit is used as MV 2k The valve must then be designed in accordance with the pressure difference and the speed of pressure change, for example with a stronger magnetic circuit with a larger armature and / or a stronger return spring.

[0345] Alternatively, the pressure gradient and / or the pressure difference can be defined during the pressure buildup via software via regulation, so that a dynamic pressure buildup does not lead to a tensioning of the solenoid valve.

[0346] Since the pressure range is smaller in the control of the driving dynamics system described here than in a standard brake system and since the braking torque can also be built up via the electric traction motor, the MV- 2k The valve requirements are lower than in standard brake systems.

[0347] Regardless of the selected variant, for MV 2k Valve-specifically, the solenoid valve is designed without a parallel non-return valve or no non-return valve is arranged in parallel in the hydraulic line in the hydraulic connection between the wheel brakes R1 , R2 or the hydraulic consumer Vx and the pressure supply.

[0348] The aim is to be able to keep the pressure in the wheel brake constant while changing the pressure in the other wheel brake. This is a major difference from standard brake systems, where the pressure in one wheel brake can only be maintained by a pressure regulator via the pre-pressure; this greatly restricts the freedom in pressure regulation in standard brake systems and also greatly increases the difficulty of diagnosing wheel brake failures, not to mention that they cannot be diagnosed, because in the case of a wheel circuit failure it is not possible to identify whether the solenoid valve, the non-return valve or the hydraulic power is the cause.

[0349] If you use MV 2k -valve, the wheel brake can be safely isolated from the pressure supply mechanism regardless of the cause of failure. Therefore, it is possible to switch the electrohydraulic brake system EHB of the m circuit to the brake system of the m-1 circuit. Figure 9a A single-circuit EHB is obtained from a two-circuit EHB with two wheel brakes, or a two-circuit EHB is obtained from a three-circuit EHB with Vx.

[0350] exist Figure 6aIn the case shown in FIG. 1 , a three-circuit EHB is obtained from a four-circuit EHB. Figure 6b The EHB of two circuits is obtained from the EHB of three circuits.

[0351] The first configuration is characterized in that MV 2k The valve seat of the valve is connected to the circulation circuit and its armature chamber is connected to the pressure regulator.

[0352] This design allows innovative pressure regulation with bidirectionally acting inlet / outlet valves and forward and return movements of the piston of the piston-cylinder unit via current or piston control and simulated pressure gradient-controlled pressure release. In one embodiment, the pressure build-up takes place sequentially in a known multiplex method. Alternatively, dead times for the pressure build-up can be avoided by means of an electric traction motor via a braking torque gradient, which is possible when there is an electric traction motor for wheel-individualized drives. Alternatively, the braking torque build-up can also take place exclusively via the traction motor of the axle, which is possible in particular when both wheels have the same braking torque increase at the two wheels of the axle.

[0353] If a simulated pressure build-up is required and no electric traction motor is available for support, the pressure build-up can also be carried out simultaneously by time control of the valves, that is, a variable pre-pressure is preset by the piston and the same valve is closed earlier than a second valve. Pressure release is carried out in a simulated manner at multiple wheel brakes via piston control with the aid of a pressure-volume characteristic curve and PWM control of the valves or current regulation of the valves. That is, a variable flow cross section is set via the current so that different pressure release gradients can be achieved.

[0354] This regulation is otherwise expressed as PPC-Gen2-V1 (Second generation piston pressure control with valve connection V1: Inlet / outlet valve MV with valve seat at wheel brake 2k ).

[0355] Figure 9b Description: A motor driven by a transmission, with a MV 2k The structure of the pressure regulator of the piston-cylinder unit of the switching valve, the valve seat of the switching valve and the Figure 9a Differently connected to the hydraulic line leading to the pressure regulator and the armature chamber of the switching valve is connected to the wheel brake. In addition, an outlet valve is optionally provided.

[0356] This design makes it possible to implement a second pressure control variant PPC-Gen1-V2, which has a bidirectional inlet / outlet valve MV 2k and the forward and return movement of the piston of the piston-cylinder unit via current or piston control and the pressure build-up controlled by analog pressure gradients. MV 2k Valve design and Figure 9a The configuration shown in FIG. 1 is similar and can be transferred to PPC pressure regulation or pressure control and electronic device ECU1 with redundancy. EHB ECU2 EHB The same applies to the preferably redundant design of the motor and the sensors α / U, i / U.

[0357] In one embodiment, the known multiplexing method is used in sequence with a time delay Δt MUX Or pressure relief via timed control of the outlet valve, as is known from classic ABS systems.

[0358] However, in contrast to the prior art, the pressure release can also be carried out in an analog manner in the first wheel circuit (R2) via the inlet / outlet valve by means of piston control according to the pressure-volume characteristic curve, while in the second wheel circuit (R1') it is carried out via the outlet valve. This can avoid the time delay Δt MUX .

[0359] This allows very rapid pressure relief in critical driving situations, such as high μ or μ-Sprung. In another control state, such as low μ, that is, when adjusting for ice and snow, control can be performed using the known multi-path method. Thus, a combination of pressure relief methods can achieve very short braking distances in all driving situations.

[0360] The combination of pressure relief via an outlet valve and inlet / outlet valves has the additional advantage that normally open MVs designed for high pressure differences and volume flows do not have to be used. 2k -valve, because when the pressure is released MV 2k The valve does not have to be flowed through with a high flow rate, since the pressure relief takes place via the outlet valve with a high pressure gradient.

[0361] In addition, MV 2k The valve is thus further less stressed during pressure relief, since the electrohydraulic brake unit EHB for the vehicle dynamics system is designed for a maximum pressure of a maximum of 140 bar and, as in Figure 8a It is explained in the foregoing that the valve does not have to be resistant to a pressure of 160 bar to 220 bar. That is, a modified standard inlet valve of an ESP unit with a typical valve opening cross section, but without a parallel non-return valve, can be used in the described embodiment. The advantages of not having a parallel non-return valve are described above with reference to Figure 9a Described and similarly applicable to Figure 9b .

[0362] By means of an advantageous combination with an outlet valve, the pressure can be released quickly in all driving situations, thereby also significantly reducing the dynamic requirements on the drive motor of the pressure regulator. If the control is carried out in the MUX method in most operating states, the hydraulic brake circuit can be operated mainly in a closed brake circuit. This makes it possible to dispense with the critical re-delivery of the hydraulic flow in the control operation, which is typically used in open systems according to the prior art (DE 10 2018 212 905 A1), which are controlled according to the method described in EP 2 580 095 B1. The re-delivery of volume in open systems is increasingly considered critical, since interruptions of more than 100 ms can lead to critical driving situations.

[0363] Furthermore, the brake system integrated into the driving dynamics system described here can take over more functions besides pure ABS control operation, such as further brake torque interventions, such as torque vectoring interventions. As a result, hydraulic volume can be lost in the open circuit.

[0364] If the MV according to the invention is also used 2k -valve as a switching valve, it can be similar to the reference Figure 9a The described situation also diagnoses a turbine circuit failure and allows the turbine circuit to continue to be operated even at low leakage, which is not possible in systems according to the prior art with parallel nonreturn valves.

[0365] This adjustment is represented here as PPC-Gen2-V2 (Second generation piston pressure control with valve connection V2: Inlet / outlet valve MV with valve seat at the pressure supply 2k ).

[0366] Alternative to normally open solenoid valve MV 2k , it is also possible to use a standard inlet valve of an ABS / ESP unit which is designed according to the pressure difference and the speed of pressure change, for example with a stronger magnetic circuit and / or a stronger return spring. Since the pressure range of the vehicle dynamics system described here for regulation is smaller than that of a standard brake system, the requirements on the solenoid valve are lower.

[0367] As an alternative to a piston-cylinder unit with inlet / outlet valves, a simple pump can also be used, for example a double-piston pump in an ABS pump according to the prior art or a gear pump according to WO 2021 005151A1. In a double-piston pump, the pressure release is regulated via the outlet valve and the pressure build-up is regulated via the pre-pressure and PWM control of the inlet valve. If a gear pump is used, there are the same degrees of freedom as in the piston-cylinder unit, since the pressure can be selectively achieved via the outlet valve or via the gear pump by a change in the direction of rotation. This embodiment has cost advantages, but has disadvantages in terms of the accuracy of the brake torque regulation due to leakage in the gear pump.

[0368] Fig.10 An advantageous “architecture II” for a driving dynamics system of an electric axle is shown, in which a plurality of brake units are respectively active at the front axle and the rear axle.

[0369] Braking unit is used for wheel brake traction motor TM1, TM2, TM3, hydraulic pressure regulator EHB HA , EHB VA The central control unit takes over the control of the braking torque and sends the desired signal to the axle controller S-ECU. VA 、S-ECU HA Therefore, contacts similar to "Architecture I" preferably implement the following functions:

[0370] (A) Foundation braking with thermal management and energy flow management of traction motors;

[0371] (B) AEB with electronic brake force distribution (EBV);

[0372] (C) regenerative braking at multiple axles;

[0373] (D) ABS control with basic brake torque support and / or common brake torque control;

[0375] (E) Braking operation when the electro-hydraulic brake unit EHB-Z, EHB-VA fails;

[0376] (F) yaw moment intervention or wheel-individualized brake torque intervention; and / or

[0377] (G) Wheel-individualized braking torque intervention for wheel-individualized regenerative braking.

[0378] The vehicle dynamics system transmits a desired value, which includes in particular a braking torque or a braking pressure. For certain functions (e.g. the functions (C), (F), (G) described above), desired signals for pressure control or pressure regulation are also predefined, for example control signals for solenoid valves for functions such as switching duration of the opening time, PWM frequency or alternatively current curve when changing the pressure with a throttled valve cross section, and / or a prepressure for a pressure supply device for pressure build-up or pressure relief.

[0379] In addition, M-ECU 域 It can also have a controller or domain M-ECU for autonomous driving AD The interface of the vehicle control system can evaluate other information that is helpful for effective and predictive regulation. This is, for example, camera information about the road surface conditions (snow, ice, rain) or information about the environment (distance to pedestrians and / or other vehicles).

[0380] Reference Fig.11a A first embodiment of an axle module is described. In the example described, electric brake units EMB1 , EMB2 are provided at each wheel and, in addition, an electric traction motor TM1 is provided for the axle.

[0381] The axle S-ECU - axle controller communicates with the electric brake units EMB1, EMB2 and the electric traction motor TM1 and sends corresponding desired signals, so that the braking torque is preferably adjusted simultaneously by means of the electric brake units EMB1, EMB2 and the traction motor TM1. In this case, the braking torque is preferably also applied additively to the wheels in the regulating mode.

[0382] Thus, for example, a basic braking torque is preferably established using the traction motor TM1, which reduces the magnitude of the braking torque of the EMB module (see above with reference to Figure 5 In addition, the basic braking torque of the traction motor TM1 can also be reduced simultaneously with the EMB braking torque of the wheel brake, thereby enabling a higher braking torque gradient. This is particularly important in critical driving situations such as μ-Sprung (see above with reference to Figure 5b Description of the control situation). This can also be used advantageously to simplify the EMB module with a low maximum force and lower power of the drive motor of the EMB.

[0383] Reference Fig.11b A further embodiment is described. In this case, an electrohydraulic pressure regulator EHB is combined with an EMB module in the axle module, wherein the pressure regulator is preferably based on Figure 9a and 9b structure and enables individual adjustment of the wheels.

[0384] This allows wheel-individual adjustment to be carried out selectively via the EMB module or by means of the electrohydraulic brake unit EHB.

[0385] This allows for maximum freedom in the pressure regulation.

[0386] This also enables redundancy in wheel-specific pressure control, as required, for example, for SAE levels 4-5, so that the ABS control function can be implemented redundantly and also in two different designs of the brake torque regulator. This is particularly advantageous in meeting redundancy requirements.

[0387] Such an arrangement is conceived in particular for the front axle of an autonomously driven vehicle, where higher requirements must be met than at the rear axle, for example with regard to steerability and a large influence on the braking distance.

[0388] This bridge configuration can also be used to simplify steer-by-wire systems that typically have two steering actuators, wherein the steering actuators are also equipped with 2×3 phase windings. Steering can thus be simplified by the braking torque, since a safe, redundant steering can be ensured by the braking torque. This results in cost savings of up to 100 Euros in the steering process.

[0389] Alternatively, it is also conceivable to have a pressure regulator with only one hydraulic circuit at both wheel brakes, which, however, is not possible in Fig.11b . As an alternative to the piston-cylinder unit, a simple rotary pump in the form of a gear pump is also conceivable, by means of which pressure can be built up and released. In this embodiment, an axle-type braking torque can be applied. The hydraulic pressure regulator then acts in a supporting role in the control, similar to the traction motor, but due to the missing power limitation, the deceleration can also reach up to the locking pressure. This makes axle-type ABS functions possible, which is completely sufficient for regulating the rear axle when wheel-individualized control is implemented at the front axle.

[0390] If there is a rear axle Fig.11b system and with the front axle Fig.11a The system combination can realize three-channel ABS operation and yaw torque regulation.

[0391] Reference Fig.11c A further embodiment is described with an electrohydraulic brake unit EHB and two electric traction motors TM1 and TM2. In this case, one traction motor is provided for each wheel.

[0392] Alternatively, the electrohydraulic brake unit EHB is designed as shown for wheel-individual control, but the electrohydraulic brake unit EHB can also be conceived only as a single-circuit device.

[0393] The rear axle of the vehicle is expediently equipped with such a configuration and the electrohydraulic brake unit EHB is used for redundancy purposes for ABS and yaw torque control for stability intervention and steering intervention. At low μ, the ABS is controlled via the traction motor and supported by the EHB, while at high μ, the ABS is controlled via the EHB and supported by the traction motor. Anti-slip control is carried out exclusively via the traction motors TM1 and TM2. Such an axle is expediently equipped with cost-effective drum brakes.

[0394] Reference Fig.11d A further embodiment is described in which the traction motor TM1 is combined with an electrohydraulic brake unit EHB. Fig.11a , with the difference that the electric brake unit EMB is replaced in its function by an electrohydraulic brake unit EHB.

[0395] exist Fig.12 The maximum braking torque gradients as a function of vehicle deceleration for an exemplary maximum speed of 200 km / h are shown in FIG. 1 with the aid of the following exemplary designs: a typical brake unit single box (curve 1210), an ESP-standard with a storage chamber (curve 1220), an electric traction motor (curve 1240), an electric traction motor with an RSP-4Q inverter (curve 250), and a design for high braking torque gradients, preferably with a normally open MV 2k - Valve pressure regulator with PPC-2Gen-V1 or V2 pressure regulation (curve 1260).

[0396] Furthermore, a corresponding curve for "MUX2.0" is shown (curve 1230), wherein in MUX2.0, a second generation multiplexing method is integrated, as described, for example, in this specification (see also Figure 9a and 9b Description of the invention) Pressure regulation PPC-Gen2-V1 and PPC-Gen1-V2. In the system, normally open valves are used in particular and a distinction is made between different valve connections and pressure regulation methods. In PPC-Gen2-V1, the valve seat is connected to the wheel brake, in PPC-Gen2-V2, the valve seat is connected to the pressure supply unit. In both methods, bidirectional flow through the valve takes place and the pressure is changed in one direction of pressure change via volume regulation; in the other direction of pressure change, the pressure is optionally changed in a throttling manner or only via time control of the valve by means of regulation of the opening cross section of the valve. The second generation multiplexing method is distinguished from the first generation multiplexing method (MUX1.0) in that in the MUX1.0 method, the pressure is changed in both directions of pressure change only via volume control / volume regulation. In addition, pressure relief is achieved at the wheel brake via at least one outlet valve. This generally results in a higher pressure change gradient than when using a single tank and ESP.

[0397] Furthermore, three regions I to III are defined:

[0398] At a smaller deceleration Region I In the area I, the electric brake unit EMB and the electric traction motor can achieve particularly high braking torque gradients due to the principle. Standard ESP systems with a storage chamber have the smallest gradients, because the counterpressure acts in the storage chamber, while single-tank brake systems have the advantage of releasing the pressure into a reserve container. Therefore, in area I, where deceleration is important, typically for example for ABS control on snow and ice or in normal ACC braking operation, the electric brake unit EMB or the traction motor is preferably used for braking torque control.

[0399] exist Region III In the case of large decelerations, the electrohydraulic system (with pressure regulator, preferably PPC-Gen2 regulation, single box) again has great advantages and preferably takes over the ABS regulation.

[0400] in between Region II In this case, a sufficient braking torque gradient can be achieved with all the brake units. Preferably, the first braking torque regulator with a small braking torque gradient then supports the ABS control with a constant braking torque, while the ABS control is taken over by the more dynamic pressure regulator.

[0401] If the accumulated braking torque caused by the accumulation of the braking torque gradients of the two braking torque regulators over the total deceleration range is linearized, a high braking torque gradient can be ensured over the total deceleration range. Ideally, the preferred features are useful for streamlining the brake unit: thus, motors with low drive torque and power can be used for EMB and EHB and / or smaller control valves can be used. In particular, in this case, a cost-effective EHB pressure regulator with a trapezoidal lead screw can be realized, which is only suitable for a lower pressure range due to the lead screw load caused by the higher pressure.

[0402] If the pressure regulator with MUX control is operated sequentially, the dead time can be reduced in the control cycle by intervention in the brake torque of the other units, so that the MUX control, which loses its significance due to disadvantages in extreme cases (e.g. at high μ), becomes relevant again. This has the particular advantage that the brake system is then completely closed and the control can be described via a mathematical model. The complex pressure estimation model and application work, as is the case with ABS systems open for calibration, is then not necessary. Automatic application is therefore also possible.

[0403] Reference Fig.12aThe following describes by way of example how the desired braking torque for the wheel brakes of the front axle of the vehicle is determined by the control unit. 底盘控制 The vehicle model implemented in includes, for example, modeling data for weight distribution, friction coefficient of the road surface, tire condition and the effect of brake pressure on the deceleration of the vehicle. In particular, the following values ​​are transmitted to the controller M-ECU of the front axle: VA : Expected value M of the expected braking torque for the right front wheel soll,VR and the desired value M of the desired braking torque for the left front wheel soll,VL , the speed of the vehicle V Fzg , speed of the right front wheel V VR and the speed V of the left front wheel VL , the differential torque of the right front wheel ΔM soll,VR The differential torque ΔM between the left front wheel and soll,VL and the coefficient of friction of the road surface.

[0404] M-ECU controller on the axle VA In particular, an Mn characteristic curve diagram of the traction motor TM is stored, which describes the dependency of the deceleration achieved by the traction motor on the speed of the vehicle or the rotational speed of the traction motor, and another characteristic curve diagram is stored, which describes the relationship between the achievable braking torque gradient and the deceleration of the vehicle for available brake units or traction motors.

[0405] Based on the data, the controller M-ECU VA Determine the desired torque M of the first traction motor for the front axle soll,TM1 and the desired torque M of the second traction motor soll,TM2 , the desired torque M of the electromechanical brake unit for the first wheel soll,EMB,R1 and the desired torque M of the electromechanical brake unit for the second wheel soll,EMB,R2 and the desired torque M of the electrohydraulic brake unit for the first wheel soll,EHB,R1 and the desired torque M of the electrohydraulic brake unit for the second wheel soll,EHB,R2 In this case, the method is adapted to which brake unit is actually available.

[0406] Then, the desired braking torque M of the right front wheel is obtained from the value soll,brems,VR and the desired braking torque M of the left front wheel soll,brems,VL .

[0407] Similarly, the same method can be carried out for the rear axle or for all wheels of the vehicle.

[0408] Reference Fig.13An advantageous "architecture III" for a wheel module driving dynamics system is described, in which two brake units are active at each wheel. For example, traction motors TM1, TM2, TM3, TM4 and electric brake units EMB modules EMB1, EMB2, EMB3, EMB4 can be used as brake units for wheel braking.

[0409] The central control unit takes over the control of the braking torque and sends the desired signals to the controllers S-ECU for the individual wheels or axles. 轮1 、S-ECU 轮2 、S-ECU 轮3 、S-ECU 轮4 .

[0410] The following functions are preferably achieved by this, similar to Architectures I and II:

[0411] (A) Foundation braking with thermal management and energy flow management of traction motors;

[0412] (B) AEB with electronic brake force distribution (EBV);

[0413] (C) regenerative braking at multiple axles;

[0414] (D) ABS control with basic brake torque support and / or common brake torque control;

[0416] (E) Braking operation when the electric brake unit EHB-Z, EHB-VA fails;

[0417] (F) yaw moment intervention or wheel-individualized brake torque intervention; and / or

[0418] (G) Wheel-individualized braking torque intervention for wheel-individualized regenerative braking.

[0419] In implementing the function, according to the characteristic diagram, in particular the braking torque gradient, such as Fig.12 As shown in FIG, the braking torque is distributed to the electric traction motor and the EMB depending on the deceleration of the vehicle, wherein, in contrast to other architectures, the braking torque modulation is preferably performed by the electric brake unit EMB in all driving states, and only the basic braking torque is provided via the electric traction motor of the corresponding wheel, which is particularly used to streamline the electric brake unit EMB. This is preferably utilized more effectively when the wheel brakes warm up. In the event of a brake unit failure, the control operation is then taken over by the corresponding other brake unit, optionally with a limitation of the maximum achievable deceleration, but with fully redundant control functions at all wheels.

[0420] Reference Fig.13aAn exemplary embodiment of the architecture is described. In the wheel modules, electromechanical brakes EMB (EMB1-EMB4) are combined with electric traction motors (TM1-TM4) so ​​that one wheel module in each case forms an assembly and is respectively controlled via a wheel module controller (M-ECU-Wheel1 to M-ECU-Wheel4). The respective wheel module controller synchronizes the torque control of the electric traction motors in time and distributes the braking torque differently to the EMB and the traction motor TM depending on the driving situation, such as the friction coefficient or the speed.

[0421] Preferably, the traction motor and the EMB each have a further controller (ECU-EMB, ECU-TM) which contains in particular the output stage of the converter and the motor control and operates at a faster clock speed, while the decision heuristics and the characteristic diagram are preferably represented in the wheel module controller M-ECU-Wheel.

[0422] Furthermore, the wheel module controllers (M-ECU Wheel 1 to M-ECU Wheel 4) communicate with the central control unit (M-ECU Domain), where in particular the wheel speeds V R1 To V R4 and in particular further sensor signals S1 , S2 , Si.

[0423] It is conceivable that the wheel module controllers (ECU-Wheel 1 to M-ECU-Wheel 4) also detect the wheel speed V R1 To V R4 and sensor signals S1, S2, Si. The wheel module controller can also implement the functions of the central control unit (M-ECU domain) redundantly.

[0424] This makes it possible to selectively perform wheel-individualized regulation via the EMB module or the traction motor. This allows for maximum freedom in pressure regulation, but also redundancy in wheel-individualized pressure regulation, as required, for example, for SAE levels 4-5. In particular, the ABS regulation function can be implemented redundantly and also with two different structural forms of the brake torque regulator, which is particularly advantageous in terms of meeting redundancy requirements. Therefore, even in the event of a wheel module failure, a much safer and more reliable regulation with a short braking distance and the possibility of yaw moment regulation can always be achieved with three wheel modules. If either the electric brake unit EMB or the traction motor fails in the wheel module, the corresponding other, non-failed component takes over the regulation of the braking process.

[0425] This results in different design variants.

[0426] a) The electric brake unit EMB is designed to achieve a locking pressure so that in the event of a traction motor failure, braking with maximum deceleration is still possible via the electric brake unit EMB; however, a large reserve for attenuation (typically 100%) is omitted, that is, the electric brake unit EMB has only a small reserve, for example 20-40%, in addition to the maximum braking torque without heating.

[0427] b) The electric brake unit EMB and the electric traction motor TM are therefore designed so that the maximum deceleration is achieved by combining the braking torque of the EMB with the braking torque of the TM, and the friction brake is designed according to the maximum braking torque of the electromechanical brake unit EMB. In addition, as explained above with respect to "Architecture I", suitable precautions and control strategies are required so that braking via the regenerative braking torque of the traction motor does not cause battery damage, especially in the fully charged state. For example, the strategies here are: (1) feedback into the battery up to the limit of power consumption, (2) field-oriented regulation (Id / Iq current regulation) of the electric motor so that the energy in the motor is dissipated internally, (3) additional dissipation of energy obtained by the electric traction motor in generator operation, or (4) use of an electrical intermediate storage designed for pulsed power, such as a supercapacitor.

[0428] Variant b) is the preferred design because the greatest potential for reducing costs and weight exists here. However, in the first introduction scenario of the technology, variant a) can be meaningful in the sense of minimizing risks.

[0429] The two mentioned variants a) and b) provide sufficient safety for SAE Class 5, since the vehicle can be decelerated with high vehicle stability and even ABS operation, not only in the event of a failure of a component of a wheel module, but also in the event of a complete wheel module failure. The braking distance is only compromised at high speeds and decelerations.

[0430] The system described at present, in particular the driving dynamics system, and the vehicle and method can realize a large cost saving in the core part of the vehicle, namely braking and steering. In addition, it is possible to achieve a considerable saving in terms of weight, which in turn causes further cost saving.

[0431] By optimally utilizing the potential of regenerative braking by means of one or more electric traction motors, the dissipative braking system can be smaller in size, since it only has to apply a smaller portion of the total braking torque. Thus, the problem of fading when the friction brakes heat up excessively can likewise be reduced.

[0432] A: AD level 2

[0433] For example, if, as described above for FDS variant A1, the Figure 3 The basic braking function (function a) is optimized by the driving dynamics system and the central control and masking strategy, that is to say, for example, regenerative braking via the traction motor up to 51% at the front axle and up to 71% at the rear axle, so that the heating of the wheel brakes can be minimized.

[0434] This has two positive effects on costs: On the one hand, the brake system can be designed for lower pressures, which reduces the costs of the electrohydraulic brake unit EHB, and on the other hand, the dimensions of the basic brake can be significantly thinner. This can be achieved, for example, by smaller brake discs, smaller brake pads and also more cost-effective materials. Thus, cost-effective drum brakes can also be used both on the front axle and on the rear axle.

[0435] In FDS variant A2, for example, in order to simplify Figure 6b In the case of an electrohydraulic brake system, the traction motor can be configured at the rear axle in such a way that the torque can be generated wheel-individually, either by a traction motor with a torque vectoring module or preferably by distributing the power of the 130 kW motor to two electric traction motors TM1, TM2, each with 65 kW. The latter embodiment with two motors is advantageous because the dynamic braking torque can be varied independently of one another at the two wheels.

[0436] Furthermore, if, as explained above, the braking torque is synchronously adjusted via the vehicle dynamics system via the electric traction motor and the electrohydraulic brake module EHB, in which in particular one brake unit provides a basic braking torque and a second brake unit provides a regulated additional braking torque (depending on the Figure 5 The cost and weight of the system can be further significantly reduced if an adjustment strategy is adopted.

[0437] On the one hand, it can be especially based on Figure 6a The embodiment reduces the costs for the electrohydraulic brake unit EHB by fewer and more cost-effective valves and again lower maximum pressure and volume. Therefore, instead of a ball screw drive, a cost-effective trapezoidal screw can also be used. In addition, it is possible to use drum brakes not only at the front axle but also at the rear axle.

[0438] In FDS variant A3, for example, only one twin traction drive (TM1, TM2) with a power of, for example, 230 kW can be used at the rear axle in the third optimization step. Figure 7b The RSP-4Q inverter can be significantly expanded again according to the Figure 7a The operating range of the regenerative braking in the motor characteristic curve diagram.

[0439] This allows the rear axle to be decelerated over the entire vehicle speed range up to the maximum speed solely via the electric traction motors. If the control functions described above are also performed via the electric traction motors TM1 and TM2 , the basic brakes at the rear axle can be completely dispensed with.

[0440] In addition to this, no hydraulic lines to the rear axle and no regulating valves are then required, so that the electrohydraulic brake unit EHB only has to be designed for the front axle of the vehicle (see Figure 6c ). Here, a cost-effective trapezoidal thread can also be used.

[0441] B: AD Level 3-4

[0442] If, in variant B1 of a driving dynamics system with a two-box system (eg X-Boost 3 and ESP), a Figure 8 If the electrohydraulic brake system in FIG. 1 is integrated into the vehicle dynamics system as described, not only can the redundancy requirements of SAE Level 4 be met, but the electrohydraulic brake unit EHB can also be implemented more cost-effectively by reducing costs.

[0443] Furthermore, the costs and weight of the friction brakes can be reduced by brake support via the electric traction motor already in the basic brake function (a). Costs can be reduced still further by using cost-effective disc brakes, especially at the front axle, and drum brakes at the rear axle.

[0444] If, in a variant B2 of a driving dynamics system with a central EHB-Z, a control system according to Figure 6a Electrohydraulic brake system and the use of traction motors at both axles for support in the basic braking and control functions according to the control of the driving dynamics system described here, the redundant functions described above can be utilized in addition, as described above with reference to Figure 6a The functional redundancy level for AD classes 3-4 is achieved by the described embodiment with redundancy of the pressure supply device. It is also assumed here that the hydraulic brake system is implemented in a four-circuit manner and can still be operated in a three-circuit manner in the event of a failure.

[0445] C: AD Level 5

[0446] Variant C1 of the vehicle dynamics system with an electromechanical brake unit EMB is based on the third specific embodiment described above, in which a control ECU (S-ECU) is provided for each wheel module. 轮1 、S-ECU 轮2 、S-ECU 轮3 、S-ECU 轮4), which jointly regulates the torque of the drive motor and EMB. It is thereby possible to reduce various costs and weight both in the basic brake function and in the control mode via the vehicle dynamics system by simultaneous brake torque regulation.

[0447] In a first step, the EMB can be significantly downsized, since a lower maximum torque is required.

[0448] Compared to a two-box solution, the EMB described here is also significantly simpler to use and integrate into the central control of the vehicle dynamics system. Another advantage is independence from the brake manufacturer.

[0449] If an EMB is used in a wheel module according to the "Architecture III" of the driving dynamics system, the electric power steering EPS can also be optionally omitted, since steering is possible by means of different motor speeds via the wheel motors. Even in the FDS variant C2 with an EHB axle module with a piston-cylinder unit, the EHB can be significantly reduced, since a lower maximum torque can certainly be achieved. By means of joint braking with the aid of the traction motor and the EHB, the friction brake can also be implemented significantly more easily and cost-effectively. This allows the two pressure regulators to reach a lower cost level and also provide the redundancy required for SAE Class 5.

[0450] Further cost reductions are possible by using drum brakes.

[0451] If, in contrast to the above-mentioned Optimization 2, Variant C3 is used for the EHB of the rear axle with a simple pump (dual-piston pump, gear pump), it is possible to achieve the same control quality with a pump as with a piston-cylinder unit, although this is less critical at the rear axle. Furthermore, it is possible to generate only the basic torque with the pump and to generate the controlled additional braking torque with the traction motor(s) at the rear axle.

[0452] Here, too, the use of drum brakes at the rear axle can achieve further cost reductions.

[0453] In variant C4 with a central EHB-Z, suitability for AD classes 3-4 has already been investigated and even suitability for AD class 5 has been described. The actuation unit can therefore be omitted.

[0454] The use of drum brakes at the rear axle enables additional cost and weight reductions compared to an electromechanical brake unit EMB.

[0455] Overall, it was determined that the variants C2-C4 described here reach the cost level of an SAE Level 2 solution, but meet all redundancy requirements for SAE Level 5. The variants can therefore be classified as target-guided solutions for the highest extended level of autonomous driving.

[0456] Compared to the EMB variant, this solution has the great advantage that components produced in large quantities, for example for hydraulic pressure supplies or solenoid valves, are already available, so that a rapid series introduction is also possible without high capital costs.

[0457] Another example is described in addition:

[0458] In another example, a driving dynamics system (FDS) or an electric vehicle having central control utilizing a driving dynamics system (FDS) having one of FDS architectures I, II, or III includes:

[0459] at least one wheel brake (RB1 to RB4),

[0460] at least one electric traction motor (TM1, TM2, TM3, TM4) which serves not only for driving but also for braking the axles or wheels,

[0461] at least one braking device (EMB, EHB) for generating a braking torque(s) at one or more wheel brakes,

[0462] Central Computer (M-ECU 域 ), by means of which the central computer controls not only at least one electric traction motor (TM1 to TM4) but also at least one braking device (EHB, EMB) during braking via a control unit (M-ECU 域 、S-ECU 车桥 、S-ECU 车轮 ) are jointly controlled, and the desired signal is sent to the controller of one (or more) traction motors (TM1 to TM4) and the brake device (EHB, EMB) for implementation,

[0463] a central computer having: at least one of the core functions ABS, ESP, EBV, ASR, ACC, AEB, recuperation management with regenerative braking via electric traction motors at a plurality of axles and / or at least one of the core functions (A) to (G) being regulated or controlled via the central computer, wherein

[0464] During normal braking, braking is performed with the electric traction motors (TM1 to TM4) even at high vehicle speeds (>80 km / h), and when braking via the electric traction motors (TM1 to TM4) an EBV function (EBV = Electronic Brake Force Distribution at the front and rear axles) is simultaneously implemented, and / or

[0465] In control operation (e.g. ABS, ESP), a braking torque is generated by means of at least one traction motor (TM1 to TM4) and simultaneously at least one EHB or EMB, and braking torque regulation is performed at at least three wheels of the vehicle by means of a brake unit (EMB, EHB) and / or an electric traction motor (TM1 to TM4), so that the braking torque can be adjusted at the three wheels of the vehicle in each driving state.

Claims

1. A driving dynamics system for a vehicle, comprising: - at least one wheel brake (RB1, RB2, RB3, RB4) for dissipative braking of one wheel of the vehicle; - at least one brake unit (EMB, EHB) associated with the at least one wheel brake (RB1, RB2, RB3, RB4) and configured to generate a dissipative braking torque by means of the at least one wheel brake (RB1, RB2, RB3, RB4); - at least one electric traction motor (TM1, TM2, TM3, TM4) which can be controlled to generate a regenerative braking torque for at least one wheel or axle of the vehicle; as well as a central control unit (M-ECU domain) configured to control the at least one brake unit (EMB, EHB) and the at least one electric traction motor (TM1, TM2, TM3, TM4) for a braking function combined with one another, such that a combined braking torque can be generated by means of the at least one brake unit (EMB, EHB) and the at least one electric traction motor (TM1, TM2, TM3, TM4); It is characterized in that The braking function relates to a control situation in which a basic braking torque and a regulated additional braking torque are controlled and / or regulated simultaneously; wherein - optionally, the basic braking torque is generated by the at least one brake unit (EMB, EHB) and the regulated additional braking torque is generated by the at least one electric traction motor (TM1, TM2, TM3, TM4); or - generating the basic braking torque by means of the at least one electric traction motor (TM1, TM2, TM3, TM4) and generating the regulated additional braking torque by means of the at least one brake unit (EMB, EHB); or The at least one brake unit (EMB, EHB) and the at least one electric traction motor (TM1, TM2, TM3, TM4) respectively jointly generate the basic braking torque and the regulated additional braking torque.

2. The driving dynamics system according to claim 1, It is characterized in that The braking function is selected from one of the following functions: Automatic emergency braking (AEB), in particular by means of EBV control, in particular with EBV control at the rear axle and the front axle of the vehicle, wherein the total braking torque is distributed to the rear axle and the front axle; an anti-lock braking system (ABS), in particular with basic braking torque support via at least one traction motor (TM1, TM2, TM3, TM4); -Electronic Stability Program (ESP); - Electronic Brake-force Distribution (EBV); - Anti-slip Regulation (ASR); - Distance adjustment (Automatic Cruise Control, ACC); - Recycling management, in particular for the recycling of individual axles or wheels; - Foundation brakes with thermal management; - Yaw moment control in case of failure of wheel brakes (RB1, RB2, RB3, RB4); and / or -Yaw moment intervention control for steering support.

3. The driving dynamics system according to claim 1, It is characterized in that The brake unit (EMB, EHB) comprises an electric drive (M) and is designed as an electrohydraulic brake unit (EHB) or as an electromechanical brake unit (EMB).

4. The driving dynamics system according to claim 1, It is characterized in that The brake unit (EHB) is designed as an electrohydraulic brake unit (EHB) with an electrically operated pressure supply unit; wherein a valve device is provided between the pressure supply unit and at least one wheel brake (RB1, RB2, RB3, RB4) or a plurality of wheel brakes (RB1, RB2, RB3, RB4) of the axle (HA, VA); The valve arrangement comprises a normally open wheel valve (MV 2k,1 , M.K. 2k,2 , MV 2k,3 , MV 2k,4 ) and / or circuit isolation valve (MV 2k,TV ), wherein in the event of leakage of at least one wheel brake (RB1, RB2, RB3, RB4), the valve device is configured to isolate the wheel brake (RB1, RB2, RB3, RB4) concerned by closing, and the central control unit (M-ECU domain) is configured to control the at least one brake unit (EMB, EHB) and / or the at least one electric traction motor (TM1, TM2, TM3, TM4) so ​​that a braking torque regulation is performed at other wheels of the vehicle, in particular at at least three wheels; In particular, wheel brakes (RB1, RB2) of axles (VA) of the vehicle, in particular wheel brakes (RB1, RB2) of the front axle (VA), can be isolated by means of the valve device.

5. The driving dynamics system according to claim 1, It is characterized in that The central control unit (M-ECU domain) is coupled to at least one brake unit controller (S-ECU axle, S-ECU wheel) of the brake unit (EMB, EHB).

6. The driving dynamics system according to claim 1, It is characterized in that The central control unit (M-ECU domain) is configured to transmit the desired signal to the motor controller (ECU-TM1, ECU-TM2, ECU-TM3, ECU-TM4) of the at least one traction motor (TM1, TM2, TM3, TM4) and to the brake unit controller (S-ECU axle, S-ECU wheel) of the at least one brake unit (EHB, EMB) during the braking function.

7. The driving dynamics system according to any one of the preceding claims, It is characterized in that The central control unit (M-ECU domain) is further configured to control the at least one electric traction motor (TM1, TM2, TM3, TM4) for regenerative braking of the vehicle when the speed of the vehicle exceeds 80 km / h for braking in normal operation; wherein during the regenerative braking, electronic brake force distribution (EBV function) is implemented simultaneously at the front axle and the rear axle of the vehicle; In particular, 20% to 40% of the total braking torque acts on the rear axle of the vehicle and 60% to 80% of the total torque acts on the front axle of the vehicle.

8. The driving dynamics system according to claim 1, It is characterized in that The wheel brakes (RB1, RB2, RB3, RB4) of the wheels (R1, R2, R3, R4) of the vehicle are associated with their own brake units (EMB1, EMB2, EMB3, EMB4); in - in particular, the brake units (EMB1, EMB2, EMB3, EMB4) are of electromechanical design; in - In particular for each of two of said wheels (R1, R2, R3, R4), a brake unit (EMB1, EMB2, EMB3, EMB4) associated with said wheel brake (RB1, RB2, RB3, RB4) and an electric traction motor (TM1, TM2) are integrated into a wheel module.

9. The driving dynamics system according to claim 1, It is characterized in that A common brake unit (EHB1, EHB2) is associated with the wheel brakes (RB1, RB2, RB3, RB4) of two wheels (R1, R2, R3, R4) of an axle (HA, VA) of the vehicle; - In particular, the brake units (EHB1, EHB2) are of electrohydraulic design; wherein In particular, a first brake unit (EHB1) is associated with the two wheels (R1, R2) of the rear axle (HA) and a second brake unit (EHB2) is associated with the two wheels (R3, R4) of the front axle (VA).

10. The driving dynamics system according to claim 1, It is characterized in that The wheel brakes (RB1, RB2, RB3, RB4) of the four wheels (R1, R2, R3, R4) of the vehicle are associated with a central brake unit (EHB-VA); In particular, the central brake unit (EHB-VA) is of electrohydraulic design.

11. The driving dynamics system according to claim 1, It is characterized in that A common brake unit (EHB-VA) is associated with the wheel brakes (RB1, RB2) of two wheels (R1, R2) of a first axle (VA), in particular a front axle (VA) of the vehicle; - In particular, the brake unit (EHB-VA) is of electrohydraulic design; wherein - in particular in the wheel brakes (RB1, RB2) of the first axle (VA) a wheel-individualized dissipated braking torque can be set, in particular by means of a solenoid valve in a hydraulic line between the brake unit (EHB-VA) and the wheel brakes (RB1, RB2), wherein - in particular the brake unit (EHB-VA) can also be connected via hydraulic lines to the wheel brakes (RB1, RB2) of two wheels (R1, R2, R3, R4) of a second axle (HA), in particular a rear axle (HA); In particular, a common, non-wheel-individualized dissipated braking torque can be set in the wheel brakes (RB3, RB4) of the second axle (HA).

12. The driving dynamics system according to claim 1, It is characterized in that A first pair of two wheels (R1, R2) of a first axle (HA), in particular a rear axle (HA), of the vehicle is associated with a first electric traction motor (TM1), and a second pair of wheels (R3, R4) of a second axle (VA), in particular a front axle (VA), of the vehicle is associated with a second electric traction motor (TM3).

13. The driving dynamics system according to claim 1, It is characterized in that A first wheel (R1) and a second wheel (R2) of a first axle (HA), in particular a rear axle (HA) of the vehicle are each associated with a dedicated electric traction motor (TM1, TM2).

14. The driving dynamics system according to claim 14, It is characterized in that The first wheel (R1) and the second wheel (R2) are also associated with their own brake units (EMB1, EMB2); wherein in particular the respective brake units (EMB1, EMB2) are electromechanically designed; wherein In particular for the first wheel (R1) and the second wheel (R2), the respectively associated electric traction motor (TM1, TM2) and the respectively associated brake unit (EMB1, EMB2) are integrated into a wheel module respectively associated with the first wheel (R1) or the second wheel (R2).

15. The driving dynamics system according to claim 14 or 15, It is characterized in that Furthermore, a third electric traction motor (TM3) is commonly associated with the third wheel (R3) and the fourth wheel (R4) of the second axle (VA), in particular the front axle (VA) of the vehicle; - in particular the third wheel (R3) and the fourth wheel (R4) are associated with a common brake unit (EHB2); in particular the common brake unit (EHB2) is of electrohydraulic design; in particular the third electric traction motor (TM3) and the common brake unit (EHB2) are integrated into an axle module associated with the second axle (VA); or in particular - in particular a central brake module (EHB-Z) is provided, which is in particular of electrohydraulic design, wherein by means of the central brake module (EHB-Z) a wheel-individualized braking torque can be generated for the first wheel (R1) and the second wheel (R2) and a common braking torque can be generated for the third wheel (R3) and the fourth wheel (R4).

16. The driving dynamics system according to claim 1, It is characterized in that The central control unit (M-ECU domain) is configured to distribute the basic braking torque and the adjusted additional braking torque to the at least one brake unit (EMB, EHB) and the at least one electric traction motor (TM1, TM2, TM3, TM4) according to the vehicle deceleration and / or according to the friction coefficient of the road surface; wherein - the electric brake unit (EMB) and / or the at least one electric traction motor (TM1, TM2, TM3, TM4) generates the regulated additional braking torque, in particular in the case of lower decelerations and / or lower friction coefficients, for example in the case of ABS control on snow or ice or in the case of deceleration in ACC braking operation; in - in particular in the case of greater deceleration and / or greater friction coefficients, for example during braking on asphalt, the electrohydraulic brake unit (EHB) generates the regulated additional braking torque; in - In particular, at medium decelerations and / or medium friction coefficients, the brake unit (EHB, EMB) or the traction motor (TM1, TM2, TM3, TM4) generates the basic braking torque as a constant braking torque, and the further brake unit (EMB, EHB) or the traction motor (TM1, TM2, TM3, TM4) generates the regulated additional braking torque.

17. The driving dynamics system according to any one of the preceding claims, It is characterized in that The central control unit (M-ECU domain) is configured to implement EBV regulation during automatic emergency braking (AEB); wherein The braking torque gradients of the at least one brake unit (EMB, EHB) and of the at least one electric traction motor (TM1, TM2, TM3, TM4) are taken into account so that the maximum braking torque is reached simultaneously at the front axle (VA) of the vehicle and at the rear axle (HA) of the vehicle.

18. The driving dynamics system according to claim 1, It is characterized in that During the regenerative braking, in particular when the battery of the vehicle is fully charged, at least one of the following strategies is used: - Feeding back the regenerated energy into the battery up to the limit of power absorption; - field-oriented regulation (Id / Iq current regulation) of the electric traction motor so that the energy in the motor is dissipated internally; - dissipating the energy obtained by the electric traction motors (TM1, TM2, TM3, TM4) in generator mode, supplying the obtained energy to electrical consumers of the vehicle and / or warming up a fluid reservoir for use with a heat pump for cooling or heating; and / or - Use of electrical intermediate storage devices designed for pulsed power, such as supercapacitors.

19. The driving dynamics system according to claim 1, It is characterized in that The at least one electric traction motor (TM1, TM2, TM3, TM4) is operated by an inverter, wherein the inverter is used to switch the winding of the at least one electric traction motor (TM1, TM2, TM3, TM4) into a series connection or a parallel connection of three branches of the excitation coil of the brushless motor; - In particular, four-quadrant operation can be achieved with the aid of the inverter, namely having: quadrant 1 with positive rotational speed and positive torque of the electric motor, quadrant 2 with positive rotational speed and negative torque of the electric motor; quadrant 3 with negative rotational speed and positive torque of the electric motor, and quadrant 4 with negative rotational speed and negative torque of the electric motor.

20. The driving dynamics system according to any one of the preceding claims, It is characterized in that The central control unit (M-ECU domain) is configured to perform the brake control according to a characteristic curve group; wherein In particular, the characteristic diagram depicts a pressure-volume characteristic when the wheel brake is heated up, a relationship between motor current and brake pressure and / or a relationship between brake pressure and / or deceleration.

21. The driving dynamics system according to claim 1, It is characterized in that The central control unit (M-ECU domain) is configured to acquire sensor data during vehicle operation, in particular in a state after the vehicle is put into operation for the first time, for example during driving operation or in a stationary state before or after driving operation, and to adapt the control of the brake function based on the acquired sensor data by means of artificial intelligence methods, in particular machine learning or neural networks; wherein - In particular, the artificial intelligence method can be implemented by means of a computer of the central control unit (M-ECU domain); wherein - the adaptation is carried out in particular in a safe state of the vehicle, in particular in a stationary state of the vehicle; wherein - determining a characteristic diagram, in particular based on the acquired sensor data, which characteristic diagram depicts, for example, a pressure-volume characteristic curve when the wheel brake is heated up, a relationship between motor current and brake pressure and / or a relationship between brake pressure and / or deceleration; in In particular, if a deviation from a current characteristic map is detected, for example due to environmental influences, air in the system or due to a heating of the wheel brakes, the characteristic map can be adapted as a function of the sensor data and the artificial intelligence method.

22. A driving dynamics system for a vehicle, comprising: - at least one electric traction motor (TM1, TM2, TM3, TM4) which can be controlled to generate regenerative braking torque for at least one wheel or axle of the vehicle; and a central control unit (M-ECU domain) configured to control the at least one electric traction motor (TM1, TM2, TM3, TM4) for a braking function; It is characterized in that The central control unit (M-ECU domain) is configured to brake on a road surface with a low friction coefficient, in particular on snow, ice and / or wet road conditions, at a low to moderate speed, in particular less than 0.5 m / s 2 The deceleration rate implements the braking function; wherein in particular the central control unit (M-ECU domain) is configured to carry out the braking function by means of at least one traction motor of at least one axle of the vehicle, in particular by means of two traction motors of a rear axle of the vehicle.

23. A vehicle having a driving dynamics system according to any one of the preceding claims.

24. A method for operating a driving dynamics system, the driving dynamics system having: at least one brake unit (EMB, EHB) for generating a dissipative braking torque and at least one electric traction motor (TM1, TM2, TM3, TM4) for generating a regenerative braking torque for at least one wheel or axle of a vehicle; and a central control unit (M-ECU domain), the central control unit controlling the at least one brake unit (EMB, EHB) and the at least one electric traction motor (TM1, TM2, TM3, TM4) for a braking function, wherein in the method: - generating a combined braking torque by means of the at least one brake unit (EMB, EHB) and the at least one electric traction motor (TM1, TM2, TM3, TM4); in The braking function relates to a control situation in which a basic braking torque and a regulated additional braking torque are controlled and / or regulated simultaneously; in - optionally, controlling said at least one brake unit (EMB, EHB) to generate a basic braking torque and controlling said at least one electric traction motor (TM1, TM2, TM3, TM4) to generate said regulated additional braking torque; or - controlling the at least one electric traction motor (TM1, TM2, TM3, TM4) to generate the basic braking torque, and controlling the at least one brake unit (EMB, EHB) to generate the regulated additional braking torque; or - controlling the at least one brake unit (EMB, EHB) and the at least one electric traction motor (TM1, TM2, TM3, TM4) to jointly generate the basic braking torque and the regulated additional braking torque, respectively.

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