Method for wheel slip control on a wheel of a vehicle and control system for a friction brake system and an electric motor of a vehicle that can be operated in a recuperative mode

Abstract

The present invention relates to a control system and a method for wheel slip control on a wheel (16) of a vehicle by determining, during braking of the wheel (16) by means of a friction braking system (12) of the vehicle and simultaneously by means of an electric motor (14) of the vehicle operated in a recuperative mode, whether a speed deviation from a current speed (n, n) m ) of the wheel (16) or of the electric motor (14) from a predetermined target speed (n0, n 0m ) of the wheel (16) or of the electric motor (14) exceeds a predetermined limit value, and, if necessary, specifying at least one first target value (n0) with respect to a first target reduction of an amount of a friction braking torque (M) friction ) and at least one second target value (n 0m ) regarding a second target reduction of the magnitude of a generator braking torque (M motor) such that even if the sum of an amount of the first target reduction and an amount of the second target reduction is less than the amount of the friction braking torque (M friction ) and / or less than the magnitude of the generator braking torque (M motor ) is, the amount of the first target reduction is greater than zero and the amount of the second target reduction is greater than zero.

Description

[0001] The present invention relates to a method for controlling wheel slip on a wheel of a vehicle. The invention also relates to a control system for a friction braking system and an electric motor of a vehicle that can be operated in a recuperative mode, as well as a corresponding computer program and a storage medium. State of the art

[0002] A conventional approach for jointly controlling an electric motor of a vehicle that can be operated in a recuperative mode and simultaneously a friction brake system of the same vehicle is disclosed, for example, in DE 10 2011 075 968 A1. Disclosure of the invention

[0003] The present invention provides a method for wheel slip control on a wheel of a vehicle with the features of claim 1 and a control system for a friction brake system and an electric motor of a vehicle that can be operated in a recuperative mode with the features of claim 6. Advantages of the invention

[0004] The present invention provides advantageous possibilities for optimizing / shortening the braking distance of a vehicle decelerated by means of its friction braking system and its electric motor operating in a recuperative mode, by improving the control accuracy of the wheel slip control system performed during deceleration. Compared to purely hydraulic or purely motor-based / purely electric wheel slip control systems known from the prior art, the use of the present invention results in efficiency optimization by enabling greater energy recovery through increased recuperation efficiency. Since, compared to purely hydraulic wheel slip control, the use of the present invention results in fewer valve actuations and fewer post-sniffing cycles, NVH (noise, vibration, and harshness) problems are virtually eliminated during wheel slip control.Compared to conventional purely hydraulic wheel slip control, in which the pressure build-up gradients that can be achieved by means of the respective pump or plunger system are significantly limited, this conventional disadvantage is also eliminated when using the present invention.

[0005] As will become clear from the following description, the present invention can be implemented in a comparatively simple manner (essentially) solely by means of a corresponding design / programming of the respective control electronics of the vehicle in question. Therefore, the use of the present invention is also comparatively inexpensive and requires no additional hardware or sensors on the vehicle.

[0006] In an advantageous embodiment of the method, the at least one first target value, taking into account the speed deviation, and the at least one second target value, taking into account the speed deviation, are set such that even if the sum of the amount of the first target reduction and the amount of the second target reduction is less than the amount of the friction braking torque and / or less than the amount of the generator braking torque, the amount of the first target reduction is greater than or equal to 10% of the sum of the amount of the first target reduction and the amount of the second target reduction, and the amount of the second target reduction is greater than or equal to 10% of the sum of the amount of the first target reduction and the amount of the second target reduction.The embodiment described here thus implements a so-called "distributed wheel slip control" using the friction brake system as a hydraulic actuator and the electric motor, operating in its recuperative mode, as an electric actuator to jointly utilize the dynamics of the friction brake torque and the electric motor. Simultaneously, central setpoint generation for the "distributed wheel slip control" is possible, optionally at the wheel, axle, or vehicle level.

[0007] In particular, the at least one first target value, taking into account the speed deviation, and the at least one second target value, also taking into account the speed deviation, can be set such that even if the sum of the magnitude of the first target reduction and the magnitude of the second target reduction is less than the magnitude of the friction braking torque and / or less than the magnitude of the generator braking torque, the magnitude of the first target reduction is greater than or equal to 20% of the sum of the magnitude of the first target reduction and the magnitude of the second target reduction, and the magnitude of the second target reduction is greater than or equal to 20% of the sum of the magnitude of the first target reduction and the magnitude of the second target reduction. Such a "distributed wheel slip control" achieves an advantageous combination of hydraulic and electric wheel slip control.

[0008] As an advantageous further development, at least a third target value can be defined for another wheel of the axle on which the electric motor exerts its generator braking torque. This target value relates to a target increase in the magnitude of a friction braking torque exerted on the other wheel by means of the friction braking system, taking into account at least one second target value. The at least one electrically controllable component of the friction braking system is controlled with additional consideration of the at least one third target value. In this way, it can be ensured that the braking of the other wheel is not, or hardly, affected by the wheel slip control system implemented on the wheel of the same axle.

[0009] Preferably, when controlling the at least one electrically controllable component of the friction brake system, taking into account the at least one first setpoint and the electric motor, at least one first control signal is output to a first control unit of the at least one electrically controllable component of the friction brake system, and at least one second control signal is output to a second control unit of the electric motor, taking into account the at least one second setpoint. The friction brake torque is readjusted by means of the first control unit controlled by the at least one first control signal according to the at least one first setpoint, and the generator brake torque is readjusted by means of the second control unit controlled by the at least one second control signal according to the at least one second setpoint.In this way, the magnitude of the friction braking torque can be readjusted by means of the first control unit controlled by the at least one first control signal according to the at least one first setpoint, and the magnitude of the generator braking torque can be readjusted by means of the second control unit controlled by the at least one second control signal according to the at least one second setpoint.

[0010] The advantages described above are also guaranteed with a suitable control system for a friction braking system and an electric motor of a vehicle that can be operated in a recuperative mode.

[0011] The present invention further relates to a computer program comprising instructions that cause the control system described above and below to execute the method described above and below, and to a machine-readable storage medium on which the computer program is stored. Brief description of the drawings

[0012] Further features and advantages of the present invention are explained below with reference to the figures. They show: Fig. 1 a schematic representation of a first embodiment of the control system; Fig. 2 a schematic representation of a second embodiment of the control system; Fig. 3a to 3c a flowchart and coordinate systems to explain an embodiment of the method for wheel slip control on a wheel of a vehicle; and Fig. 4A and Fig. 4B Fourteen coordinate systems to explain the advantages of the method of Fig. 3a to 3c. Embodiments of the invention

[0013] Fig. Figure 1 shows a schematic representation of a first embodiment of the control system.

[0014] It is expressly pointed out that the control system 10a to 10c described below can be used on (almost) any vehicle equipped with a friction brake system 12 and an electric motor 14 that can be operated in a recuperative mode (for braking the vehicle). The friction brake system 12 does not refer to an electric motor that can be operated in a recuperative mode. The friction brake system 12 could, for example, be a hydraulic braking system of the vehicle. Although the term "electric motor" is used only in the singular below for the sake of clarity, the vehicle can also be equipped with several motor units encompassed by the electric motor 14, by means of which the vehicle can be braked in recuperative mode.The usability of the control system 10a to 10c described below is not limited to any specific friction brake system type of the friction brake system 12, to any particular motor type of the electric motor 14 that can be operated in a recuperative mode, and to any specific vehicle type / motor vehicle type.

[0015] The control system 10a to 10c comprises at least one electronic device 10a to 10c. By means of the at least one electronic device 10a to 10c of the control system 10a to 10c, wheel slip control for at least one wheel 16 of the vehicle is implemented under the influence of a friction braking torque M. friction non-zero and simultaneously under the influence of a generator braking torque M motor Non-zero is executable. Under the friction braking torque M friction This refers to a first braking torque applied to the wheel 16 by means of the friction braking system 12. This corresponds to the generator braking torque M. motorA second braking torque is meant, effected by the electric motor 14 on the wheel 16 and / or an axle of the vehicle equipped with the wheel 16. Although the usability of the at least one electronic device 10a to 10c of the control system 10a to 10c for wheel slip control is subsequently explained only in connection with the wheel 16, the at least one electronic device 10a to 10c can also be designed / programmed for wheel slip control on at least one other wheel of the vehicle, preferably on all wheels of the vehicle. The respective wheel slip control can be understood as ABS control, vehicle dynamics control, traction control and / or agility enhancement.

[0016] To execute the wheel slip control on the wheel 16, the at least one electronic device 10a to 10c of the control system 10a to 10c is designed and / or programmed such that, by means of the at least one electronic device 10a to 10c, it can be determined / is determined for the respective wheel 16 whether a speed deviation of a provided current speed n or n m of the wheel 16 or of the electric motor 14 from a predetermined or fixed target speed n0 or n 0m of the wheel 16 or of the electric motor 14 exceeds a predefined limit. The current rotational speed n of the wheel 16 can, for example, be provided by a (not shown) speed sensor to the at least one electronic device 10a to 10c of the control system 10a to 10c. Similarly, the current rotational speed n of the electric motor 14 can be provided by a (not shown) speed sensor. mto which at least one electronic device 10a to 10c of the control system 10a to 10c must be output.

[0017] If the speed deviation exceeds the specified limit, the amount of the friction braking torque M is / will be determined by means of at least one electronic device 10a to 10c. friction as well as an amount of the generator braking torque M motor Reducible / reduced. For this purpose, it is ensured by means of a design and / or programming of the at least one electronic device 10a to 10c that at least one first target value n0 with respect to a first target reduction of the magnitude of the friction braking torque M is achieved by means of the at least one electronic device 10a to 10c. friction taking into account the speed deviation and at least one second target value n 0m regarding a second target reduction of the magnitude of the generator braking torque M motortaking into account the speed deviation, the values ​​can be determined / are determined. Furthermore, the at least one electronic device 10a to 10c is additionally designed and / or programmed such that even if the sum of the amount of the first target reduction and the amount of the second target reduction is less than the amount of the friction braking torque M friction and / or smaller than the magnitude of the generator braking torque M motor is, the amount of the first target reduction is greater than zero and the amount of the second target reduction is greater than zero.

[0018] By means of the design and / or programming of the at least one electronic device 10a to 10c of the control system 10a to 10c, it is ensured that wheel slip control, which is executed at wheel 16 when the limit value is exceeded due to the speed deviation, is carried out partly by means of the friction brake system 12 due to the magnitude of the first target reduction being greater than zero, and simultaneously / additionally by means of the electric motor 14 due to the magnitude of the second target reduction being greater than zero. It is expressly pointed out here that this simultaneous / joint execution / action of the wheel slip control at wheel 16 using the actuators 12 and 14 also occurs if the sum of the magnitude of the first target reduction and the magnitude of the second target reduction is less than the magnitude of the friction brake torque M. friction and / or smaller than the magnitude of the generator braking torque M motorA conventional wheel slip control system could be implemented using only the friction brake system 12 (i.e., a so-called purely hydraulic wheel slip control system) and / or a conventional wheel slip control system could be implemented using only the electric motor 14 (i.e., a so-called purely motor-based wheel slip control system). As will become clear from the following description, this joint / simultaneous execution / action of the wheel slip control system using actuators 12 and 14 enables a more optimized wheel slip control system compared to the prior art, which can contribute in particular to shortening the vehicle's braking distance. Likewise, by jointly / simultaneously executing / action the wheel slip control system using both actuators 12 and 14, braking comfort for the vehicle's driver can be increased, especially by reducing noise.

[0019] The control system 10a to 10c described here, unlike the prior art, therefore does not rely primarily or preferably exclusively on wheel slip control by means of the friction brake system 12 or exclusively on means of the electric motor 14. Instead, preferably or always, both actuators 12 and 14 are actively used for wheel slip control, even if the respective wheel slip control could be implemented as a purely hydraulic wheel slip control or as a purely motor-based wheel slip control.

[0020] Preferably, the at least one electronic device 10a to 10c is designed and / or programmed such that even if the sum of the amount of the first target reduction and the amount of the second target reduction is less than the amount of the friction braking torque M friction and / or smaller than the magnitude of the generator braking torque M motoris, which includes at least one first target value n0 taking into account the speed deviation and at least one second target value n 0m Taking into account the speed deviation, the at least one electronic device 10a to 10c is set such that the amount of the first target reduction is greater than or equal to 10% of the sum of the amount of the first target reduction and the amount of the second target reduction, and the amount of the second target reduction is greater than or equal to 10% of the sum of the amount of the first target reduction and the amount of the second target reduction. In particular, it is also possible if the sum of the amount of the first target reduction and the amount of the second target reduction is less than the amount of the friction braking torque M. friction and / or smaller than the magnitude of the generator braking torque M motor is, which includes at least one first target value n0 taking into account the speed deviation and at least one second target value n0m Taking into account the speed deviation, the at least one electronic device 10a to 10c is used to determine such that the amount of the first target reduction is greater than or equal to 20% of the sum of the amount of the first target reduction and the amount of the second target reduction, and the amount of the second target reduction is greater than or equal to 20% of the sum of the amount of the first target reduction and the amount of the second target reduction. This allows the advantages of using both actuators 12 and 14 together to be utilized even more effectively.

[0021] After determining at least one first target value n0 with respect to the first target reduction of the magnitude of the friction braking torque M friction (with a non-zero value) and at least one second target value n 0m regarding the second target reduction of the magnitude of the generator braking torque M motor(with a non-zero value) are / will be sent by means of at least one electronic device 10a to 10c, taking into account at least one first target value n0, at least one first control signal 18 to a (not sketched) first control of at least one electrically controllable component of the friction brake system 12 and taking into account at least one second target value n 0m At least one second control signal 20 can be output to / is output to a (not shown) second control of the electric motor 14. In particular, the first control of the at least one electrically controllable component of the friction brake system 12 can be controlled by means of the at least one first control signal 18 such that the friction brake torque M frictionThe first control unit, triggered by the at least one first control signal 18, can be readjusted according to the at least one first setpoint n0. Preferably, the second control unit of the electric motor 14 can also be triggered by the at least one second control signal 20 such that the generator braking torque M motor by means of the second control controlled by the at least one second control signal 20 according to the at least one second setpoint n 0m The system is / will be newly adjusted. A reliable implementation of the wheel slip control at wheel 16, which is effected by both the friction brake system 12 and the electric motor 14, is thus ensured.

[0022] As an advantageous further development, the at least one electronic device 10a to 10c can additionally be designed and / or programmed such that, by means of the at least one electronic device 10a to 10c, for a (not shown) further wheel of the axle onto which the electric motor 14 applies its generator braking torque M motor This results in at least one third target value being definable / determined with respect to a target increase (non-zero) of the magnitude of a friction braking torque exerted on the other wheel by means of the friction braking system 12. If necessary, the determination of the at least one third target value is carried out by means of the at least one electronic device 10a to 10c, taking into account the at least one second target value n. 0mSubsequently, by means of at least one electronic device 10a to 10c, the at least one first control signal 18, taking into additional consideration of at least one third target value, can be output to the first control of the at least one electrically controllable component of the friction brake system 12. Thus, the second target reduction of the generator braking torque M can be achieved. motorThe braking force exerted on the axle equipped with wheel 16 and the other wheel can be compensated for by appropriately defining at least one third target value such that, despite the second target reduction (non-zero), the other wheel remains sufficiently braked. In particular, the at least one third target value can be defined such that, despite the second target reduction (non-zero), the other wheel is braked with a (nearly) constant total braking torque from the electric motor 14 (comprising the friction braking torque exerted on the other wheel by means of the friction braking system 12 and the generator braking torque M exerted on the axle by means of the electric motor 14) in a (nearly) constant total braking torque. motor ) is / is braked. In this way, an increase in the braking distance due to a decreasing braking of the other wheel attributable to the wheel slip control can be reliably prevented.

[0023] In the embodiment of the Fig. 1 The control system 10a to 10c has as its first electronic device 10a a slip target setting device 10a, by means of which it is possible to recognize when the speed deviation of the current speed n or n m of the wheel 16 or of the electric motor 14 from the target speed n0 or n 0m of the wheel 16 or of the electric motor 14 exceeds the specified limit value, and, if applicable, the at least one first target value n0 and the at least one second target value n 0mare / can be determined. Alternatively, the second electronic device 10b of the control system 10a to 10c and / or the third electronic device 10c of the control system 10a to 10c can also be designed / programmed to perform this function. The second electronic device 10b of the control system 10a to 10c is designed to control the first control of the at least one electrically controllable component of the friction brake system 12, taking into account the at least one first setpoint n0 provided by the first electronic device 10a and preferably also taking into account the current rotational speed n of the wheel 16. In the embodiment of the Fig. 1 is the at least one first target value n0, for example a target rotational speed / target wheel speed n0 of the wheel 16. The second electronic device 10b, the friction brake system 12 and the wheel 16 can together form a speed control loop 22 of the wheel 16.

[0024] The first electronic device 10a outputs at least one second setpoint n to the third electronic device 10c of the control system 10a to 10c. 0m out. In the embodiment described here, at least one second target size n 0m a target speed / target machine speed n 0m of the electric motor 14. Alternatively, at least one second target value n can be used. 0m This could also be the target rotational speed / target wheel speed n0 of wheel 16. The third electronic device 10c is then designed / programmed to take into account at least one second target value n 0m and possibly the current rotational speed n or n m The second control unit of the electric motor 14 is located at the wheel 16 or at the electric motor 14. The third electronic device 10c and the electric motor 14 can form a speed control loop 24 of the electric motor 14.

[0025] Both the speed control loop 22 of the wheel 16 and the speed control loop 24 of the electric motor 14 exhibit rapid dynamics. The second electronic device 10b and the third electronic device 10c can each also be referred to as speed controller devices 10b and 10c, respectively. As indicated by arrows 26 in Fig. As shown schematically in Figure 1, the second electronic device 10b and the third electronic device 10c can also be designed / programmed to communicate with each other. The in Fig. The schematically represented control architecture can be used both individually for each wheel and at the axle level.

[0026] Fig. Figure 2 shows a schematic representation of a second embodiment of the control system.

[0027] The in Fig. 2. Schematically represented control systems 10a to 10d show a further development of the embodiment of Fig. 1. A distribution control loop 10d is also included, which is interposed between the electronic devices 10b and 10c and the controls of the friction brake system 12 and the electric motor 14. The distribution control loop 10d comprises a central distribution controller 28, which regulates a manipulated variable distribution. This allows for the control of the in Fig. 1. The communication between electronic devices 10b and 10c, represented by arrows 26, can be omitted, as feedback of the controller outputs or controller states becomes unnecessary. Instead, a braking torque difference ΔM determined by the distribution controller 28 can be added to an output of the third electronic device 10c and subtracted from an output of the second electronic device 10b using operators 30a to 30c.

[0028] Regarding further properties of the tax system 10a to 10d of the Fig. 2 refers to the embodiment described above. Fig. 1 referred.

[0029] Fig. Figures 3a to 3c show a flowchart and coordinate systems to explain an embodiment of the method for wheel slip control on a wheel of a vehicle.

[0030] It is expressly pointed out that the procedure described below can be carried out on (essentially) any type of vehicle equipped with a friction braking system and an electric motor capable of operating in a regenerative mode (for braking the vehicle). The feasibility of the procedure described below does not require a specific type of friction braking system, a particular type of electric motor, or a specific type of vehicle.

[0031] The process, comprising steps S1 and S2, is executed while the wheel is being braked by the friction braking system and simultaneously by the electric motor operating in its recuperative mode. It is expressly noted that braking the wheel by the friction braking system and simultaneously by the electric motor means that the friction braking system generates a friction braking torque M. friction not equal to zero on the wheel and the electric motor a generator braking torque M motor effects other than zero on the wheel and / or an axle of the vehicle equipped with the wheel.

[0032] In the example of the Fig. 3a to 3c, a target total braking torque M is applied by a driver of the vehicle or by a cruise control system of the vehicle from a time t1. total 0 A value other than zero is requested. The requirement for the target total braking torque M total 0 A non-zero frictional braking torque M is generated from time t1 onwards. frictionnon-zero and a generator braking torque M motor a non-zero value, which also results in an actual total braking torque M. total as the sum of the friction braking torque M friction and the generator braking torque M motor is caused to the wheel. This is in the coordinate system of the Fig. 3b is shown, whose abscissa is the time axis t, while the ordinate of the coordinate system is used to determine the time axis. Fig. 3b the target total braking torque M total 0, the actual total braking torque M total , the friction braking torque M friction and the generator braking torque M motor are displayed.

[0033] In a process step S1 of the procedure described here, while the wheel is being braked by means of the friction braking system and simultaneously by means of the electric motor operated in its recuperative mode, it is determined whether a speed deviation of a current speed of the wheel or the electric motor from a predetermined target speed of the wheel or the electric motor exceeds a predetermined limit value.

[0034] If the speed deviation exceeds the specified limit, a process step S2 is executed. In the example of the Fig. In sections 3a to 3c, the rotational speed deviation exceeds the specified limit from time t2 (after time t1), which is why wheel slip control is initiated at that wheel from time t2. While the abscissa of the coordinate system of Fig. 3c the time axis t is, is by means of the ordinate of the coordinate system of the Fig. 3c indicates when the wheel slip control is inactive (state 0) and when the wheel slip control is active (state 1).

[0035] As shown by the coordinate system of the Fig. As can be seen in section 3b, to effect wheel slip control, both an amount of friction braking torque M are applied to the wheel. friction as well as an amount of the generator braking torque M motor This is achieved by reducing at least one initial target value with respect to a first target reduction of the magnitude of the friction braking torque M. friction taking into account the speed deviation and at least one second target value regarding a second target reduction of the magnitude of the generator braking torque M motor taking into account the speed deviation, such that even if the sum of the first target reduction and the second target reduction is less than the amount of the friction braking torque M frictionand / or smaller than the magnitude of the generator braking torque M motorThe first target reduction is greater than zero, and the second target reduction is greater than zero. Subsequently, at least one electrically controllable component of the friction brake system is controlled, taking into account the at least one first target value, and the electric motor is controlled, taking into account the at least one second target value. To control the at least one electrically controllable component of the friction brake system, taking into account the at least one first target value, and the electric motor, taking into account the at least one second target value, at least one first control signal, taking into account the at least one first target value, can be output to a first controller of the at least one electrically controllable component of the friction brake system, and at least one second control signal, taking into account the at least one second target value, can be output to a second controller of the electric motor.The friction braking torque M can then be determined. friction by means of the first control unit controlled by the at least one first control signal according to the at least one first setpoint and the generator braking torque M motor by means of the second control unit, which is controlled by at least one second control signal, is readjusted according to at least one second target value.

[0036] The coordinate system reveals the Fig. 3b also that during wheel slip control, i.e. between times t2 and t3, the actual total braking torque M total of the target total braking torque M total 0 is decoupled. During wheel slip control, the target total braking torque M applies. total 0 merely as the upper limit of the actual total braking torque M total .

[0037] As an optional further development of the procedure described here, in a process step S3 for another wheel of the axle onto which the electric motor applies its generator braking torque M total This results in at least one third target value being defined with respect to the target increase of the magnitude of a friction braking torque exerted on the other wheel by means of the friction braking system, taking into account at least one second target value. If necessary, in the (optional) process step S3, the at least one electrically controllable component of the friction braking system is also controlled, taking into account at least one third target value.

[0038] Fig. 4A and Fig. Figure 4B shows fourteen coordinate systems to illustrate the advantages of the method of Fig. 3a to 3c, where in the example of the coordinate systems of the Fig. 4Aa to 4Ag for wheel slip control, the procedure of Fig. 3a to 3c and in the comparison example of the coordinate systems of Fig. 4Ba to 4Bg implement a conventional purely hydraulic wheel slip control system, which is known to the applicant as internal prior art.

[0039] The wheel slip control systems shown as examples and comparison examples are each executed during braking with the same (not shown) target total braking torque profile at a vehicle speed of 200 kilometers per hour (km / h). In the coordinate systems of the Fig. 4A and Fig. 4B, where the abscissa is the time axis t, is used in the coordinate systems of... Fig. 4Aa and Fig. 4Ba represents the longitudinal acceleration ax and the lateral acceleration ay of the respective vehicle on the ordinate.

[0040] The ordinates of the coordinate systems of Fig. 4Ab and Fig. 4Bb exhibit a recuperation efficiency ε Fa front axle of the respective vehicle. In the coordinate systems of the Fig. 4Ac and Fig. 4Bc are represented by the ordinates as wheel slip η Fr a right wheel of the respective front axle and wheel slippage η F1 a left wheel of the respective front axle is displayed. Using the ordinates of the coordinate systems of the Fig. 4Ad and Fig. 4Bd represents a wheel-specific friction braking torque M applied to the right wheel of the respective front axle. friction Fr , a wheel-specific friction braking torque M exerted on the left wheel of the respective front axle friction FI , a front axle generator braking torque M applied (directly) to the respective front axle motor F and a recuperation limit R limit F reproduced the respective front axle.

[0041] The ordinates of the coordinate systems of Fig. 4Ae and Fig. 4Be exhibit a recuperation efficiency ε Ra rear axle of the respective vehicle. Wheel slippage η Rr a right wheel of the respective rear axle and wheel slippage η Rl The left wheel of each rear axle is determined using the ordinates of the coordinate systems of the Fig. 4Af and Fig. 4Bf is displayed. Using the ordinates of the coordinate systems of the Fig. 4Ag and Fig. 4Bg represents a wheel-specific friction braking torque M exerted on the right wheel of the respective rear axle. friction Rr , a wheel-specific friction braking torque M exerted on the left wheel of the respective rear axle friction Rl , a wheel-specific generator braking torque M exerted on the right wheel of the respective rear axle motor Rr , a wheel-specific generator braking torque M exerted on the left wheel of the respective rear axle motor Rl , and a recuperation limit R limit Rthe respective rear axle. (While the front axle generator braking torque M caused by the electric motor motor F (The force is applied directly to the respective front axle equipped with the front wheels; the rear wheels of the respective rear axle are braked wheel-specifically by means of the electric motor.)

[0042] As can be seen from a comparison of the coordinate systems of the Fig. 4A and Fig. 4B is recognizable by means of the procedure of Fig. 3a to 3d: The slip target (in contrast to conventional purely hydraulic wheel slip control) can be regulated much more precisely. This effect is particularly noticeable at the rear axle. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2011 075 968 A1

[0002]

Claims

[1] Method for controlling wheel slip on a wheel (16) of a vehicle comprising the steps: Determine, during braking of the wheel (16) by means of a friction braking system (12) of the vehicle and simultaneously by means of an electric motor (14) of the vehicle operated in a recuperative mode, such that the friction braking system (12) generates a friction braking torque (M) friction ) non-zero on the wheel (16) and the electric motor (14) a generator braking torque (M motor ) non-zero on the wheel (16) and / or an axle of the vehicle equipped with the wheel (16) cause a speed deviation from a current speed (n, n m ) of the wheel (16) or of the electric motor (14) from a predetermined target speed (n0, n 0m ) of the wheel (16) or of the electric motor (14) exceeds a predetermined limit (S1); and If the speed deviation exceeds the specified limit, reduce at least one amount of the friction braking torque (M). friction) and / or an amount of the generator braking torque (M motor ); characterized by the step - at least one first target value (n0) with respect to a first target reduction of the magnitude of the friction braking torque (M) friction ) taking into account the speed deviation and - at least one second target value (n 0m ) regarding a second target reduction of the magnitude of the generator braking torque (M motor ) taking into account the speed deviation such that even if the sum of an amount of the first target reduction and an amount of the second target reduction is less than the amount of the friction braking torque (M friction ) and / or less than the magnitude of the generator braking torque (M motor ) is, the amount of the first target reduction is greater than zero and the amount of the second target reduction is greater than zero; and Head to - at least one electrically controllable component of the friction brake system (12) taking into account at least one first target value (n0) and - of the electric motor (14) taking into account at least one second target value (n 0m ) (S2). [2] Method according to claim 1, wherein the at least one first target value (n0) is taken into account the speed deviation and the at least one second target value (n 0m ) taking into account the speed deviation, such that even if the sum of the amount of the first target reduction and the amount of the second target reduction is less than the amount of the friction braking torque (M friction ) and / or less than the magnitude of the generator braking torque (M motor) is, the amount of the first target reduction is greater than or equal to 10% of the sum of the amount of the first target reduction and the amount of the second target reduction, and the amount of the second target reduction is greater than or equal to 10% of the sum of the amount of the first target reduction and the amount of the second target reduction. [3] Method according to claim 2, wherein the at least one first target value (n0) is taken into account the speed deviation and the at least one second target value (n 0m ) taking into account the speed deviation, such that even if the sum of the amount of the first target reduction and the amount of the second target reduction is less than the amount of the friction braking torque (M friction ) and / or less than the magnitude of the generator braking torque (M motor) is, the amount of the first target reduction is greater than or equal to 20% of the sum of the amount of the first target reduction and the amount of the second target reduction, and the amount of the second target reduction is greater than or equal to 20% of the sum of the amount of the first target reduction and the amount of the second target reduction. [4] Method according to any one of the preceding claims, wherein - for another wheel of the axle onto which the electric motor (14) applies its generator braking torque (M motor ) causes at least a third target value with respect to a target increase of an amount of friction braking torque exerted on the further wheel by means of the friction braking system (12) taking into account the at least one second target value (n 0m ) is determined, and - wherein the at least one electrically controllable component of the friction brake system (12) is controlled taking into account the at least one third target value (S3). [5] Method according to one of the preceding claims, wherein when controlling the at least one electrically controllable component of the friction brake system (12) taking into account the at least one first setpoint (n0) and the electric motor (14) taking into account the at least one second setpoint (n 0m ) - at least one first control signal (18) taking into account the at least one first setpoint (n0) to a first control of the at least one electrically controllable component of the friction brake system (12) and - at least one second control signal (20) taking into account at least one second setpoint (n) 0m ) are output to a second control of the electric motor (14), and - the friction braking torque (M friction ) by means of the first control controlled by the at least one first control signal (18) according to the at least one first setpoint (n0) and - the generator braking torque (M motor ) by means of the second control controlled by the at least one second control signal (20) according to the at least one second setpoint (n 0m ) will be readjusted. [6] Control system (10a- 10d) for a friction brake system (12) and an electric motor (14) of a vehicle that can be operated in a recuperative mode, wherein at least one electronic device (10a-10d) of the control system (10a-10d) is designed and / or programmed such that, by means of the at least one electronic device (10a-10d), a friction braking torque (M) is applied to a wheel (16) of the vehicle by means of the friction braking system (12) for a wheel (16). friction ) non-zero and simultaneously under the influence of a generator braking torque (M) on the wheel (16) and / or an axle of the vehicle equipped with the wheel (16) by means of the electric motor (14). motor) non-zero can be determined whether there is a speed deviation of a provided current speed (n, n) m ) of the wheel (16) or of the electric motor (14) from a predetermined or fixed target speed (n0, n 0m ) of the wheel (16) or of the electric motor (14) exceeds a predetermined limit; wherein, if the speed deviation exceeds the specified limit, at least an amount of the friction braking torque (M) is applied by means of the at least one electronic device (10a-10d). friction ) and / or an amount of the generator braking torque (M motor ) are reducible; characterized by , that the at least one electronic device (10a- 10d) is additionally designed and / or programmed such that by means of the at least one electronic device (10a- 10d) - at least one first target value (n0) with respect to a first target reduction of the magnitude of the friction braking torque (M) friction) taking into account the speed deviation and - at least one second target value (n 0m ) regarding a second target reduction of the magnitude of the generator braking torque (M motor ) taking into account the speed deviation, such that even if the sum of the first target reduction and the second target reduction is less than the amount of the friction braking torque (M friction ) and / or less than the magnitude of the generator braking torque (M motor ) is, the amount of the first target reduction is greater than zero and the amount of the second target reduction is greater than zero, and by means of at least one electronic device (10a-10d) - taking into account at least one first target value (n0) at least one first control signal (18) to a first control of at least one electrically controllable component of the friction brake system (12) and - taking into account at least one second target size (n 0m ) at least a second control signal (20) to a second control of the electric motor (14) are spendable. [7] Control system (10a-10d) according to claim 6, wherein the at least one electronic device (10a-10d) is designed and / or programmed such that even if the sum of the amount of the first target reduction and the amount of the second target reduction is less than the amount of the friction braking torque (M friction ) and / or less than the magnitude of the generator braking torque (M motor ) is, which includes at least one first target value (n0) taking into account the speed deviation and at least one second target value (n 0m) taking into account the speed deviation by means of the at least one electronic device (10a-10d) such that the amount of the first target reduction is greater than or equal to 10% of the sum of the amount of the first target reduction and the amount of the second target reduction and the amount of the second target reduction is greater than or equal to 10% of the sum of the amount of the first target reduction and the amount of the second target reduction. [8] Control system (10a-10d) according to claim 7, wherein the at least one electronic device (10a-10d) is designed and / or programmed such that even if the sum of the amount of the first target reduction and the amount of the second target reduction is less than the amount of the friction braking torque (M friction ) and / or less than the magnitude of the generator braking torque (M motor ) is, which includes at least one first target value (n0) taking into account the speed deviation and at least one second target value (n0m ) taking into account the speed deviation by means of the at least one electronic device (10a-10d) such that the amount of the first target reduction is greater than or equal to 20% of the sum of the amount of the first target reduction and the amount of the second target reduction and the amount of the second target reduction is greater than or equal to 20% of the sum of the amount of the first target reduction and the amount of the second target reduction. [9] Control system (10a-10d) according to one of claims 6 to 8, wherein the at least one electronic device (10a-10d) is additionally designed and / or programmed such that, by means of the at least one electronic device (10a-10d), for a further wheel of the axle onto which the electric motor (14) applies its generator braking torque (M) motor) causes at least a third target value with respect to a target increase of an amount of friction braking torque exerted on the further wheel by means of the friction braking system (12) taking into account the at least one second target value (n 0m ) can be determined, and wherein the at least one first control signal (18) can be output to the first control of the at least one electrically controllable component of the friction brake system (12) by means of the at least one electronic device (10a-10d) taking into additional consideration the at least one third setpoint. [10] Control system (10a- 10d) according to one of claims 6 to 9, wherein - the first control of the at least one electrically controllable component of the friction brake system (12) by means of the at least one first control signal (18) and - the second control of the electric motor (14) by means of the at least one second control signal (20) are controllable in such a way that - the friction braking torque (M friction ) by means of the first control controlled by the at least one first control signal (18) according to the at least one first setpoint (n0) and - the generator braking torque (M motor ) by means of the second control controlled by the at least one second control signal (20) according to the at least one second setpoint (n 0m ) can be readjusted. [11] Computer program comprising instructions that cause the control system (10a-10d) according to one of claims 6 to 10 to execute the method according to one of claims 1 to 5. [12] Machine-readable storage medium on which the computer program according to claim 11 is stored.

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