Method for braking a vehicle and control device for a vehicle brake system - Patents.com

Abstract

A method for autonomously braking a vehicle by means of a brake system is described, in which a brake torque can be generated at the wheels by means of a hydraulic brake arrangement and by means of an electric machine linked to the wheels. The hydraulic brake arrangement includes a wheel brake and a brake booster linked to a pedal and hydraulically connected to the wheel brake. Ambient data is detected, a target deceleration of the vehicle is determined on the basis of the detected ambient data, and the target deceleration is compared with a first predetermined limit value. If the target deceleration is smaller than the first limit value, a brake torque is generated at the wheels of the vehicle according to the target deceleration by the electric machine. Otherwise, the generation of a brake torque according to the target deceleration is performed at least in part by the hydraulic brake arrangement, for example by means of a brake booster, by generating a brake pressure at the wheel brakes.

Description

[Technical field]

[0001] The present invention relates to a method for braking a vehicle, in particular a road vehicle such as a passenger car, and to a control device for a vehicle braking system. [Background technology]

[0002] Hydraulic braking systems in modern vehicles typically have an electrohydraulic brake booster linked to the pedal, which, when the pedal is actuated, boosts the actuation force applied to the pedal by means of an electric drive in order to generate brake pressure at the wheel brakes by means of a piston. The brake booster can also be operated independently of the actuation of the pedal in order to generate or modify the brake pressure at the wheel brakes. Due to the mechanical link between the input rod of the brake booster and the pedal, the actuation of the brake booster usually leads to a movement of the pedal that is not caused by the driver. When a high brake pressure is generated by the brake booster, this leads to a high force at the pedal.

[0003] Furthermore, regenerative or regenerative braking methods are known, in which, in fully or partly electrically driven vehicles, an electric machine linked to each wheel of the vehicle acts as a generator to generate a braking torque on the one hand and to convert the kinetic energy of the vehicle into electrical energy on the other hand.

[0004] Patent document 1 describes a method for autonomously braking a vehicle, in which surrounding data, in particular in the form of distance data, is detected by a distance sensor and a braking force is generated by the wheel brakes if the distance data indicates that the distance to objects around the vehicle is shorter than a threshold value. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 8,694,222 Summary of the Invention

[0006] The invention provides a method for braking a vehicle having the features of claim 1, a method for braking a vehicle having the features of claim 7 and a control device for a brake system having the features of claim 10.

[0007] Preferred embodiments and developments emerge from the further dependent claims and from the description with reference to the drawing figures.

[0008] In a first aspect of the invention, a method for autonomously braking a vehicle by means of a braking system capable of generating a braking torque at a wheel by means of a hydraulic braking arrangement and by means of an electric machine linked to the wheel, the hydraulic braking arrangement comprising a wheel brake, a brake booster linked to a pedal and hydraulically connected to the wheel brake, and a brake pressure control arrangement with a pressure generating device hydraulically connected to the wheel brake, operable independently of the brake booster to generate a brake pressure at the wheel brake. The method according to this aspect of the invention comprises detecting surrounding data representative of the distance of the vehicle relative to other objects around the vehicle, e.g. other traffic participants or obstacles, determining a target deceleration of the vehicle based on the detected surrounding data, comparing the target deceleration with a predetermined first limit value, and if the target deceleration is smaller than the first limit value, generating a braking torque at the wheels of the vehicle in accordance with the target deceleration, preferably only by operation of the electric machine as a generator, and if the target deceleration is greater than or equal to the first limit value, generating a braking torque at the wheels of the vehicle in accordance with the target deceleration, optionally in addition to operation of the electric machine as a generator, at least partly by generation of a brake pressure at the wheel brakes by a hydraulic brake installation.

[0009] The idea behind this aspect of the invention is to carry out so-called functional braking, i.e. braking which is carried out autonomously without pedal actuation by the driver, by regenerative braking by the electric machine, if the limit value for the target deceleration to be achieved of the vehicle has not been reached, and only when the limit value has been reached or exceeded is the hydraulic brake system additionally utilized.

[0010] This has the advantage that for many functional braking situations the hydraulic brake system and in particular the brake booster does not have to be operated, and therefore the number of situations in which pedal movements take place without driver intervention is also reduced.

[0011] In some embodiments, it may be provided that the brake pressure at the wheel brakes is at least partially generated by a pressure generating device. For example, the brake pressure control facility may be configured for wheel-specific modification of the brake pressure, for example for implementing ABS or ESP functions. The pressure generating devices required for this, for example in the form of pumps or plungers, can be used for the pressure generation at the wheel brakes independently of the brake booster. This has the advantage that even in the case of functional braking, in which a target deceleration is required that is greater than or equal to a limit value, the operation of the brake booster is not necessarily required, and thus pedal movements that may occur in other braking situations are avoided.

[0012] In some embodiments, the method can additionally comprise: determining a brake torque generation dynamics characteristic quantity, which is representative of the dynamics with which the brake torque has to be generated, with reference to the ambient data; and comparing the brake torque generation dynamics characteristic quantity with a second predetermined limit value, whereby the brake pressure at the wheel brakes is generated at least partially by the brake booster if the brake torque generation dynamics characteristic quantity is greater than the second limit value. The brake torque generation dynamics characteristic quantity essentially characterizes the required speed or the required time gradient of the generation of the brake torque. If the brake torque has to be generated very quickly, for example in cases such as emergency braking, this can be done in an efficient manner by the brake booster.

[0013] In some embodiments, it may be provided that the brake pressure at the wheel brakes is at least partially generated by the brake booster only if the brake torque generation dynamics characteristic variable is greater than a second limit value, and accordingly the brake booster is utilized only if the pressure generating device of the brake pressure control arrangement is not able to generate the required brake torque with the required dynamics or the required gradient.

[0014] In some embodiments, it may be provided that the brake torque at the wheels of the vehicle is generated by operation of the electric machine as a generator according to the target deceleration only if the brake torque generation dynamics characteristic quantity is smaller than or equal to the second limit value, i.e. in particular in cases where the target deceleration is smaller than the first limit value, the brake pressure generation is performed by the brake booster and / or by the pressure generating device of the brake pressure control arrangement, i.e. when the brake torque generation dynamics characteristic quantity is greater than the second limit value.

[0015] In some embodiments, the pedal may be intended to be linked to an input rod of a brake booster having several sub-parts, which are spring-coupled to one another and the brake pressure at the wheel brakes is at least partly generated by the brake booster. The spring-link can generally be embodied by an elastically deformable element arranged between two sub-parts of the input rod, for example between the rod parts, for example via a spring, an elastic block, a pneumatic cylinder or in a similar manner. In this way, when the brake booster is utilized for brake pressure generation, there is the advantage that the pedal movement is reduced, in particular the forces acting at the pedal can be reduced by the spring action.

[0016] In a second aspect of the invention, a method for autonomously braking a vehicle by means of a brake system is intended, in which a brake torque can be generated at the wheels by a hydraulic brake arrangement and by an electric machine linked to the wheels, the hydraulic brake arrangement comprising wheel brakes and a brake booster linked to a pedal and hydraulically connected to the wheel brakes, the pedal being linked to an input rod of the brake booster having a number of sub-members which are coupled to one another by a spring action. The method according to this aspect of the invention comprises: detecting surrounding data representative of the distance of the vehicle to other objects in the vehicle's surroundings; determining a target deceleration of the vehicle on the basis of the detected surrounding data; comparing the target deceleration with a first predetermined limit value; generating a brake torque at the wheels of the vehicle by the electric machine according to the target deceleration if the target deceleration is smaller than the first limit value; and generating a brake torque at the wheels of the vehicle according to the target deceleration by at least partly generating a brake pressure at the wheel brakes by the brake booster if the target deceleration is greater than or equal to the first limit value.

[0017] The idea behind this embodiment of the invention is to perform functional braking, i.e. braking autonomously without the driver's pedal action, by regenerative braking of the electric machine, if the limit value for the target deceleration of the vehicle to be achieved has not been reached, and only when the limit value has been reached or exceeded, to additionally use a brake booster, the input rod of which is connected to the pedal via an elastically deformable element, for example via a spring, an elastic block, a pneumatic cylinder or in a similar manner. This reduces the number of situations in which the brake booster is used for functional braking, which reduces the frequency of pedal movements without driver intervention. If the brake booster is nevertheless used for brake pressure generation, this has the advantage that the pedal movements are reduced, in particular the force acting on the pedal can be reduced by the spring-actuated link.

[0018] In some embodiments, the method may comprise: determining a brake torque generation dynamics characteristic quantity representative of the dynamics with which a brake torque has to be generated with reference to ambient data; and comparing the brake torque generation dynamics characteristic quantity with a pre-determined second limit value, such that a brake torque is generated at the wheels of the vehicle by operation of the electric machine as a generator in accordance with the target deceleration only if the brake torque generation dynamics characteristic quantity is less than or equal to the second limit value. The brake torque generation dynamics characteristic quantity has already been described above.

[0019] In a third aspect of the present invention, a control device for a braking system of a vehicle comprises a sensor interface set up for connection with a sensor system for receiving from the sensor system ambient data representative of a distance of the vehicle relative to other objects in the vehicle's surroundings, a first output interface for connection with an electric machine operable as a motor and generator linked to a wheel of the vehicle, and a second output interface for connection with a hydraulic brake installation of the braking system having a brake booster linked to a pedal and hydraulically connected to the wheel brakes, set up for generating brake pressure in the wheel brakes, the control device being set up for generating and outputting control signals on the output interface based on the ambient data, thereby instructing the braking system to perform a method according to the first or second aspect of the present invention.

[0020] The control device may in particular be an electronic control device and may include a processor, for example in the form of one or more CPUs, ASICs, FPGAs, etc., and a data storage device, in particular a non-volatile data storage device, for example in the form of a flash memory, SD memory, hard disk, etc. The data storage device is readable by the processor and may store software executable by the processor to output control signals to the output interface on the basis of ambient data. Naturally, the control device does not necessarily have to be embodied by a single structural unit, but the functionality may be distributed among different control devices of the brake system or of the vehicle, in particular among different processors and data storage devices.

[0021] The first limit value mentioned above may in particular be 0.3 g, where g is 9.81 m / s 2 This corresponds to the value of the gravitational acceleration.

[0022] Any features or advantages stated herein in connection with one embodiment of the invention also apply to each other embodiment of the invention.

[0023] The invention will now be described with reference to the figures of the drawings, which show: [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a schematic block diagram of a vehicle having a brake system with a control device according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram illustrating a method according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] In the drawings, unless otherwise stated, the same reference numbers represent the same components or components with the same functions.

[0026] 1 shows a schematic block diagram of a vehicle 200, in particular a road vehicle such as a passenger car. As shown in FIG. 1, the vehicle 200 comprises a number of wheels 202, a sensor system 210, an electric machine 220 and a brake system 100.

[0027] In FIG. 1, purely by way of example, a two-track vehicle 200 with four wheels 202 is shown, with two wheels 202 mounted on one axle. The electric machine 220 may be, for example, a three-phase machine. In general, the electric machine 220 can operate as a motor and as a generator. As shown by way of example in FIG. 1, the electric machine 220 may be kinematically linked to the wheels 202 of one axle. Alternatively, all wheels 202 of the vehicle 200 may be linked to the electric machine 220. As a further alternative, each wheel 202 may be linked to its own electric machine 220. In general, the electric machine 220 is kinematically linked to at least one wheel 202 of the vehicle 200. When the machine 220 operates as a motor, it drives the respective wheels 202. When the machine 220 operates as a generator, it brakes or generates a braking torque at the respective wheels 202.

[0028] The sensor system 210 may comprise one or more sensors 211 set up to detect surrounding data. The surrounding data represents in particular the distance of the vehicle 200 to objects in the surroundings of the vehicle 200, for example to other traffic participants, roadway divisions, signs, houses or other obstacles. The sensor system 210 may comprise as sensors 211, for example, radar sensors, lidar sensors, ultrasonic sensors, optical sensors or similar sensors. Thus, the sensor system 210 may in particular comprise a distance sensor, which is preferably capable of detecting distance in a time-resolved manner, so that the surrounding data may also represent the time variation of the distance.

[0029] The brake system 100 includes a control device 6 and a hydraulic brake equipment 150. As shown in FIG. 1 as an example, the hydraulic brake equipment 150 includes a wheel brake 1, an electrohydraulic brake booster (BKV) 4, and a brake pressure control equipment 5 for each wheel 202.

[0030] The BKV4 has an input rod 41 kinematically linked to a pedal 3 that can be manually operated by the vehicle driver. The BKV4 includes an electric drive (not shown) that amplifies the operating force applied to the input rod 41 via the pedal 3 to slide a piston (not shown) in a cylinder (not shown). The cylinder is connected via a hydraulic line to the wheel brake 1, whereby the movement of the piston causes a change in the brake pressure in the wheel brake 1. The BKV4 can also be operated independently of the operation of the pedal 3 to generate or generally change the brake pressure in the wheel brake 1. In such a case, the pedal 3 is also pulled out or retracted together by the input rod 41 of the BKV4.

[0031] As shown diagrammatically in Fig. 1, the pedal 3 is coupled to an input rod 41, which has a number of sub-members linked together via an elastic member, for example in the form of a spring 35 as shown in Fig. 1. This has the advantage that the force exerted on the pedal 3 is reduced or limited when the BKV 4 is actuated without manual operation of the pedal 3.

[0032] The brake pressure control arrangement 5 comprises a pressure-generating device 50 which is hydraulically connected to at least one of the wheel brakes 1. In particular, the pressure-generating device 50 is hydraulically connected in parallel to the BKV 4. The brake pressure control arrangement 5 can further comprise a switchable input valve 51 and a switchable output valve 52. As shown purely diagrammatically and in a highly simplified manner in FIG. 1, the input valve 51 can be arranged in a hydraulic path connecting a pressure output of the pressure-generating device 50 with the respective wheel brake 1, and the output valve 52 can be arranged in a hydraulic path connecting an intake connection of the pressure-generating device 50 with a point located between the wheel brake 1 and the input valve 51. By operating the pressure-generating device 50 and opening and closing the valves 51, 52 in the appropriate way, the brake pressure control arrangement 5 can carry out wheel-individual brake pressure modifications, for example to carry out ABS or ESP functions.

[0033] The control device 6 may in particular be an electronic control device and may have a processor (not shown), for example in the form of one or more CPUs, ASICs, FPGAs, etc., and a data storage device (not shown), in particular a non-volatile data storage device, for example in the form of a flash memory, SD memory, hard disk, etc. The data storage device is readable by the processor and may store software executable by the processor to output output signals on the basis of input signals. Naturally, the control device does not necessarily have to be embodied by a single structural unit, but may have its functionality distributed among different control devices of the brake system 100 or the vehicle 200, in particular among different processors and data storage devices.

[0034] As symbolically shown in Fig. 1, the control device 6 has a sensor interface 63, a first output interface 64 and a second output interface 65. The interfaces 63, 64, 65 can be configured, for example, as wired interfaces, for example as bus interfaces, in particular as a CAN bus interface, or as wireless interfaces, for example as WiFi, NFC, etc. The interfaces 63, 64, 65 can be produced as physically or structurally separated interfaces. However, it is also conceivable that several of the interfaces 63, 64, 65 are combined into a single physical interface, for example into one bus connection.

[0035] 1, the sensor interface 63 is connected in signal conducting fashion to the sensor system 210, so that the control device 6 receives ambient data detected by the sensor system 210 at the sensor interface 63. The first output interface 64 is connected in signal conducting fashion to the electric machine 220, e.g. to the power electronics (not shown) of the electric machine 220. The second output interface 65 is further connected in signal conducting fashion to the BKV 4 and the brake pressure control arrangement 5, in particular to the pressure generating device 50 and optionally also to the valves 51, 52.

[0036] The control device 6 is set up to generate control signals based on the ambient data and output them at the output interfaces 64, 65 to instruct the brake system 100 to perform a method M of braking the vehicle 200, for example as shown in FIG. 2 and described below with reference to the vehicle 200 of FIG. 1.

[0037] In the method sequence diagrammatically shown in Fig. 2, in a first step M1, ambient data is detected by a sensor system 210. For example, a sensor 211 can detect the distances to objects in the vehicle's surroundings in a time-resolved manner.

[0038] In step M2, based on the detected surrounding data, the control device 6 determines a target deceleration of the vehicle 200. This may include, for example, determining a braking torque that must be applied to the wheels 202 in order for the distance of the vehicle 200 to objects in its surroundings to not be smaller than a predetermined minimum distance. The target deceleration corresponds to a negative acceleration of the vehicle 200 that is to be achieved by application of a braking torque to the wheels 202.

[0039] In step M3, the control device 6 compares the target deceleration with a first predetermined limit value, which may be, for example, 0.3 g, where g is 9.81 m / s 2 If the comparison in step M3 indicates that the target deceleration is less than the first limit value, as shown in FIG. 1 by the symbol "-", the method (M) can proceed directly to step M6 or, as shown by way of example in FIG. 1, to optional step M4.

[0040] In optional step M4, the control device 6 determines a brake torque generation dynamics characteristic quantity with reference to the surrounding data. The brake torque generation dynamics characteristic quantity represents the dynamics with which a brake torque must be generated in order to achieve the target deceleration within a predefined time span. For example, the brake torque generation dynamics characteristic quantity can be formed by a gradient of the brake torque generation, which gradient can be determined, for example, depending on the gradient of the surrounding data. That is, if the distance of the vehicle 200 to the object, which is represented by the surrounding data, is changing rapidly, this may require a rapid brake torque generation, which is represented by a high value of the brake torque generation dynamics characteristic quantity.

[0041] From step M4, the method proceeds to step M5 in which the control device 6 compares the brake torque production dynamics characteristic quantity with a second predetermined limit value. If the brake torque production dynamics characteristic quantity is less than or equal to the second limit value, as indicated by the symbol "-" in Figure 2, the method M proceeds to step M6.

[0042] In step M6, the control device 6 outputs a control signal at the first output interface 64 instructing the electric machine 220 to switch to or maintain generator operation in order to generate a braking torque pursuant to a target deceleration at the wheels 202 of the vehicle 200 linked to the electric machine 220. Optionally, it may be intended that a braking torque is generated by operation of the electric machine 220 as a generator only if the braking torque generation dynamics characteristic quantity is less than or equal to a second limit value.

[0043] If in step M3 it is determined that the target deceleration is greater than or equal to the first limit value, as indicated by the symbol "+" in Figure 2, the method proceeds to step M7. Similarly, if in optional step M5 it is determined that the brake torque production dynamics characteristic quantity is greater than a second limit value, as indicated in Figure 2 by the symbol "+" attached to the decision block symbolizing step M5, the method proceeds to step M7.

[0044] In step M7, the control device 6 outputs a control signal at the second output interface 65 to instruct the hydraulic brake installation 150 to generate a braking torque at the wheels 202 of the vehicle 200 according to the target deceleration at least in part by generating a braking pressure at the wheel brakes 1. In general, it may be intended that at least one or both of the pressure generating device 50 and the BKV4 are controlled by the control device 6 to generate a braking pressure at the wheel brakes 1.

[0045] In a first alternative of the invention, in step M7, if the input rod 41 of the brake booster 4, to which the pedal 3 is linked, has several sub-parts linked together by spring action, the brake pressure at the wheel brake 1 is generated exclusively by the BKV 4. In this way, a simple control of the system 100 is achieved. At the same time, the force generated at the pedal 3 can be reduced and a highly dynamic brake pressure generation can be achieved. In this method alternative, it may be provided that, as an option, the brake torque at the wheels 202 of the vehicle 200 linked to the electric machine 220 is generated according to the target deceleration by the operation of the electric machine 220 as a generator only if it is determined in step M5 that the brake torque generation dynamics characteristic quantity is less than or equal to a second limit value.

[0046] In a second alternative of the invention, it is provided that in step M7, at least one or both of the pressure generating device 50 and the BKV4 are controlled by the control device 6 in order to generate the brake pressure at the wheel brake 1. For example, it may be provided that the brake pressure at the wheel brake 1 is generated at least partially, optionally entirely, by the pressure generating device 50, in particular if it has been determined in step M5 that the brake torque generation dynamics characteristic quantity is less than or equal to the second limit value, but it has been determined in step M3 that the target deceleration is greater than or equal to the first limit value. This avoids the operation of the BKV4 and reduces the frequency of situations in which the pedal 3 moves without driver intervention. As an alternative or in addition to the pressure generation by the brake pressure control facility 5, in step M7, the brake pressure at the wheel brake 1 can be generated at least partially by the BKV4, in particular if it has been determined in step M5 that the brake torque generation dynamics characteristic quantity is greater than the second limit value. Optionally, it may be intended that the BKV4 only intervenes if the brake torque production dynamics characteristic variable is greater than a second limit value, thereby still limiting the use of the BKV4 to a few situations, in particular those where a highly dynamic brake pressure production is required.

[0047] Also in the second alternative of the present invention, it may be considered that the braking torque of the wheels 202 of the vehicle 200 is generated in step M6 by the operation of the electric machine 220 as a generator in accordance with the target deceleration only if the braking torque generation dynamics characteristic variable is less than or equal to the second limit value.

[0048] Regardless of whether method M is carried out based on the first or second alternative, when braking pressure is generated at wheel brake 1 by hydraulic brake equipment 150 in step M6, operation of electric machine 220 as a generator can be performed in order to partially generate the braking torque required to achieve the target deceleration.

[0049] Furthermore, the control device 6 can optionally receive the deceleration potential of the electric machine 220 as an input signal at the first output interface 64, for example from the power electronics of the electric machine 220. The deceleration potential can be defined by characteristic quantities which represent the braking torque currently deliverable by the electric machine 220 and the dynamics with which the deliverable braking torque can be generated. In steps M3 and M5, the control device 6 can further determine whether the deceleration potential of the electric machine 220 is in each case sufficient to achieve the target deceleration or to generate a braking torque with the required dynamics. If one of these conditions checked in steps M3 and M5 is not fulfilled, i.e. if the electric machine 220 cannot deliver the required braking torque or cannot deliver the required braking torque with the required dynamics, the method M proceeds to step M7.

[0050] Although the invention has been described above by way of example with reference to examples, the invention is not limited thereto but can be modified in various ways, in particular combinations of the above-described examples are also conceivable. [Explanation of symbols]

[0051] 1 Wheel brake 3 Pedals 4 Brake booster 5 Brake pressure control equipment5 6. Control device 41 Input rod 50 Pressure generating device 64 First power interface 65 Second Output Interface 100 Brake System 150 Hydraulic brake equipment 200 vehicles 210 Sensor System 202 Wheels 220 Electrical Machinery M method M1 Detection M2 Judgment M3 Comparison M4 Judgment M5 Comparison M6 Generation M7 Generation

Claims

1. A method (M) for autonomously braking a vehicle (200) by means of a braking system (100) capable of generating a brake torque at a wheel (202) by means of a hydraulic brake arrangement (150) and by means of an electric machine (220) linked to said wheel (202), said hydraulic brake arrangement (150) comprising a wheel brake (1), a brake booster (4) linked to a pedal (3) and hydraulically connected to said wheel brake (1), and a brake pressure control arrangement (5) comprising a pressure generating device (50) hydraulically connected to said wheel brake (1) and operable independently of said brake booster (4) for generating a brake pressure at said wheel brake (1), said method comprising the steps of: - detecting (M1) surrounding data representative of the distance of the vehicle (200) relative to other objects in the surroundings of the vehicle (200); determining (M2) a target deceleration of the vehicle (200) based on the detected surrounding data; A comparison (M3) of the target deceleration with a first predetermined limit value; generating (M6) a braking torque at the wheels (202) of the vehicle (200) according to a target deceleration by operation of the electric machine (220) as a generator if the target deceleration is less than a first limit value; The method (M) includes, when the target deceleration is greater than or equal to a first limit value, generating (M7) a brake torque at the wheel (202) of the vehicle (200) in accordance with the target deceleration by at least partially generating a brake pressure at the wheel brake (1) by the hydraulic brake equipment (150).

2. 2. The method (M) of claim 1, wherein the braking pressure at the wheel brake (1) is at least partially generated by the pressure generating device (50).

3. a brake torque production dynamics characteristic quantity representative of the dynamics in which a brake torque must be produced is determined (M4) with reference to the surrounding data; The brake torque production dynamics characteristic quantity is compared (M5) with a second predetermined limit value, 3. The method (M) according to claim 1 or 2, characterized in that the brake pressure at the wheel brake (1) is at least partly generated by the brake booster (4) if the brake torque generation dynamics characteristic variable is greater than a second limit value.

4. 4. The method (M) according to claim 3, wherein the brake pressure at the wheel brake (1) is at least partly generated by the brake booster (4) only if the brake torque generation dynamics characteristic variable is greater than a second limit value.

5. 5. The method (M) according to claim 3 or 4, wherein a braking torque at the wheels (202) of the vehicle (200) is generated by operation of the electric machine (220) as a generator in accordance with a target deceleration only if the braking torque generation dynamics characteristic value is less than or equal to a second limit value.

6. 10. The method (M) according to claim 9, wherein the pedal (3) is linked to an input rod (41) of the brake booster (4) having at least two partial members, the partial members being connected to one another by spring action, and the brake pressure at the wheel brakes (1) is at least partly generated by the brake booster (4).

7. A method (M) for autonomously braking a vehicle (200) by means of a braking system (100) capable of generating a braking torque at a wheel (202) by means of a hydraulic brake arrangement (150) and by means of an electric machine (220) linked to said wheel (202), said hydraulic brake arrangement (150) comprising a wheel brake (1) and a brake booster (4) linked to a pedal (3) and hydraulically connected to said wheel brake (1), said pedal (3) being linked to an input rod (41) of said brake booster (4) having at least two partial members, said partial members being coupled to one another by spring action, said method comprising the steps of: - detecting (M1) surrounding data representative of the distance of the vehicle (200) relative to other objects in the vehicle's surroundings; determining (M2) a target deceleration of the vehicle (200) based on the detected surrounding data; A comparison (M3) of the target deceleration with a first predetermined limit value; generating (M6) a braking torque at the wheels (202) of the vehicle (200) according to the target deceleration by the electric machine (220) if the target deceleration is less than a first limit value; and generating (M7) a brake torque at the wheel (202) of the vehicle (200) in accordance with the target deceleration, when the target deceleration is greater than or equal to a first limit value, at least in part by the brake booster (4) generating a brake pressure at the wheel brake (1).

8. a brake torque production dynamics characteristic quantity representative of the dynamics in which a brake torque must be produced is determined (M4) with reference to the surrounding data; The brake torque production dynamics characteristic quantity is compared (M5) with a second predetermined limit value, 8. The method (M) of claim 7, wherein a braking torque is generated at the wheels (202) of the vehicle (200) in accordance with a target deceleration by operating the electric machine (220) as a generator only if the braking torque generation dynamics characteristic value is less than or equal to a second limit value.

9. The first limit is 0.3 g, where g is 9.81 m / s ２ 13. The method according to claim 1, wherein the acceleration of gravity corresponds to a value of

10. A control device (6) for a brake system (100) of a vehicle (200), comprising: a sensor interface (63) set up for connection to a sensor system (210) for receiving from the sensor system (210) surrounding data representative of the distance of the vehicle (200) relative to other objects in the vehicle's surroundings; a first output interface (64) for connection to an electric machine (220) operable as a motor and a generator, linked to the wheels (202) of said vehicle (200); a second output interface (65) for connection to a hydraulic brake installation (150) of said braking system (100) set up to generate brake pressure at wheel brakes (1), said hydraulic brake installation (150) having a brake booster (4) linked to a pedal (3) and in hydraulic connection with said wheel brakes (1), The control device (6) is set up to generate control signals based on ambient data and output them at the output interface (64, 65) to instruct the braking system (100) to perform the method according to any one of the preceding claims.

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