DE102019204904B3 - Brake force generator and operating procedures - Google Patents

Abstract

A method for operating a brake force generator (13) for the automated generation of a brake pressure for a brake system (31) of a motor vehicle, comprising the following steps:
a) receiving a braking request (1),
b) Receiving an actual pressure (2) from at least one pressure sensor (18) with which a pressure in at least one chamber (15) of a plunger system (14) is monitored, an actual pressure gradient over time also being received in addition to an actual pressure (2) or is determined
c) Calculating a control signal (33) for controlling a brake drive (17) of the braking force generator (13) taking into account the braking request (1) and the actual pressure (2), a calculated control signal (33) being calculated so that an upper limit for a temporal actual pressure gradient is given, and
d) Output of the control signal (33) to the brake drive (17) for adapting the brake pressure in the chamber (15).

Description

State of the art

The device described here and the method described here include a hardware protection measure in a pedal-decoupled or pedal-less redundant brake system. The device described here and the method described here relate in particular to so-called “by wire” braking systems. The method and the device represent, in particular, a hardware protection measure, this hardware protection measure being achieved with the aid of pressure regulation.

More and more people are interested in being driven without having to drive a vehicle themselves. From the user's point of view, autonomous passenger transport enables significantly greater flexibility than buses and trains. At the same time, autonomous passenger transport promises considerable potential for cost savings compared to taxis.

However, autonomous passenger transport poses new challenges for vehicle manufacturers in terms of the design of braking systems. Today's motor vehicle brake systems are designed for control by a vehicle driver with constant hydraulic access to the braking force generation on the wheel. However, if the brake system fails, this ensures that the driver can still apply sufficient braking force to the wheels of the vehicle by pressing the brake pedal.

A challenge in the design of automated or autonomous or semi-autonomous brake systems and also with brake systems that are only controlled electrically ("bywire") is that these brake systems usually often have a rather unnatural braking behavior from the point of view of the normal user, which in particular As a result, automated brake systems cannot react at all, or react in an unusual or different way than conventional brake systems to unplanned increases in brake pressure. An unplanned increase in the brake pressure here also means, for example, an excessive increase in the brake pressure as a result of a request for brake pressure (brake request). In the case of a manual brake, which can be actuated by a user with a brake pedal, for example, there is usually a direct reaction to an unexpected or unexpectedly strong increase in brake pressure in that the user slightly releases the brake pedal again quite automatically. Such an automatism is usually not feasible or expensive to implement in an automated or an autonomous braking system.

In the DE 10 2014 200 071 A1 discloses a brake system for meeting the safety requirements of autonomous driving. In addition to a conventional brake-pedal-operated master brake cylinder, the brake system includes two electrically controllable pressure supply devices which can build up brake pressures on the wheel brakes independently of one another and thus a brake pressure build-up on the wheel brakes is carried out by means of the other pressure supply device if a pressure supply device is (partially or completely) fails.

Disclosure of the invention.

Against this background, a particularly advantageous operating method for a brake system and a particularly advantageous automated braking force generator for performing the method are to be described here.

1. a) Empfangen eines Bremswunsches (1),
2. b) Empfangen eines Istdrucks (2) von mindestens einem Drucksensor (18) mit welchem ein Druck in mindestens einer Kammer (15) eines Plungersystems (14) überwacht wird, wobei ein neben einem Istdruck (2) auch ein zeitlicher Istdruck-Gradient empfangen oder ermittelt wird,
3. c) Berechnen eines Ansteuerungssignals (33) zum Ansteuern eines Bremsantriebs (17) des Bremskrafterzeugers (13) unter Berücksichtigung des Bremswunsches (1) und des Istdrucks (2), wobei ein berechnetes Ansteuerungssignal (33) so berechnet wird, dass eine Obergrenze für einen zeitlichen Istdruck-Gradienten vorgegeben ist, und
4. d) Ausgabe des Ansteuerungssignals (33) an den Bremsantrieb (17) zum Anpassen des Bremsdrucks in der Kammer (15).

A method for operating a braking force generator ( 13 ) for the automated generation of brake pressure for a brake system ( 31 ) of a motor vehicle having the following steps:

1. a) Receiving a braking request ( 1 ),
2. b) Receiving an actual pressure ( 2 ) of at least one pressure sensor ( 18th ) with which a pressure in at least one chamber ( 15th ) a plunger system ( 14th ) is monitored, with an in addition to an actual pressure ( 2 ) an actual pressure gradient over time is also received or determined,
3. c) Calculating a control signal ( 33 ) to control a brake drive ( 17th ) of the braking force generator ( 13 ) taking into account the braking requirement ( 1 ) and the actual pressure ( 2 ), whereby a calculated control signal ( 33 ) is calculated in such a way that an upper limit is specified for an actual pressure gradient over time, and
4. d) Output of the control signal ( 33 ) to the brake drive ( 17th ) to adjust the brake pressure in the chamber ( 15th ).

A brake force generator for performing the method and for automatically generating hydraulic brake pressure for a brake system of a motor vehicle is described here, which has a plunger system with at least one chamber for receiving and pressing hydraulic fluid and a brake drive. The assembly including the associated secondary components is used as the braking force generator designated. The term “plunger system” primarily refers to the hydraulic components of the braking force generator. The brake drive is set up to change the volume of the at least one chamber of the plunger system and thereby cause a pressure build-up. The brake pressure generator also has at least one pressure sensor arranged on the at least one chamber for measuring a pressure build-up in the at least one chamber and for outputting a pressure value signal. The brake pressure generator also has a controller which is set up to control the brake drive for a pressure build-up in response to an electronic braking request and in response to an actual pressure which is measured with the pressure sensor.

So-called coupled brake systems or power-assisted brake systems are known today. Decoupled brake systems or power brake systems are also known. In auxiliary power brake systems, the tensioning forces required for braking are applied to the wheel brakes by the driver's foot force with the support of a brake booster. In an external power brake system, the required clamping forces are applied to the wheel brakes by stored compressed air, the stored compressed air being generated by a compressor or hydraulically. Such external power brake systems are widespread, for example, in trucks.

External power brake systems are regularly designed to be decoupled. This means that the brake pedal is decoupled from the actual brake and there is no direct (in particular mechanical) power transmission from the brake pedal to the wheel brake. Decoupled brake systems can also regularly be referred to as “by-wire” brake systems. “By wire” means as much as we do “telegraphically” or “wired”. This expresses that when the brake systems are decoupled, information that braking is to take place is transmitted from the brake pedal to the wheel brake, decoupled from the braking force. The braking force is generated on the basis of this information.

In such decoupled brake systems, so-called pedal feel simulators are also regularly used, which simulate a realistic pedal feel on the brake pedal so that the user receives feedback on the braking effect generated in the usual way. In the case of decoupled brake systems, both variants with only one pedal feel simulator and variants with several pedal feel simulators are conceivable and common.

In particularly widespread design variants, decoupled brake systems (also called “by-wire” brake systems as described above) are, however, also implemented in such a way that hydraulic penetration is still provided in the backup. In the event of a system failure, such design variants then behave like classic pedal-coupled brake systems. For this reason, a redundancy of the decoupling / the "by-wire" components is regularly dispensed with in such brake systems.

Such widespread brake systems are therefore not suitable for use in highly and fully autonomous vehicles (vehicles with a high degree of automation), because the additional safety due to the functionality of a classic auxiliary power brake system does not apply in a highly or fully autonomous operation . Therefore, in today's vehicles with a highly or fully autonomous function, an additional hydraulic brake unit must often be installed,

In some variants of vehicles with a high degree of automation (i.e. highly automated and autonomous vehicles), the driver can still be considered for at least a certain reaction time in order to manually apply braking in an emergency (in the event of a failure or partial failure of the vehicle for autonomous operation). This applies, for example, if the degree of automation of the vehicle is set up so that the driver must always be ready to react and can also perform emergency braking. If the driver can no longer be considered to perform an emergency braking because the degree of automation is too high and, in particular, reaction times that are too short would be necessary for the driver to intervene, all safety-relevant systems (such as brakes, steering, etc.) completely redundant (i.e. over your entire chain of effects). This is important because the vehicle must always be brought into a safe state in the event of a single fault in the (braking) system.

Brake systems for vehicles with a high degree of automation often present the designer with the particular challenge that very high pressures and high pressure gradients occur in such brake systems. High pressures and high pressure gradients place high loads on the braking system.

These high loads are usually produced in that the stiffness of the brake system is greatly increased by automatic actuation of valves for the autonomous actuation of the brake system. This challenge becomes encountered with the brake pressure generator described here.

The problem of increased rigidity of the braking system occurs in the same, but lessened form, in the area of ABS systems (anti-lock braking systems) and ESP systems (systems for electronic stability control) in pedal-coupled braking systems, because such systems usually also perform electronic braking interventions and here valves are switched without any significant delay, so that there is also a sudden change in the rigidity of the brake system. The resulting pressure increases / changes are almost unconsciously regulated by the coupled driver, who slightly reduces / adapts the actuation with constant pedal force.

The increased rigidity due to the switching of the valves has an effect in particular in connection with the fact that the volume drained into the storage chamber during an ABS control is conveyed back in the direction of the plunger chamber.

In this situation, the non-coordinated control and the inertia of the plunger of the brake pressure generator ensure that the plunger is advanced further, since the plunger does not notice that the ABS / ESP has closed the valves. Information on this can be provided by the ABS / ESP, but is then only available in the plunger system with a time delay due to the latency due to the transmission via a bus system and can therefore not be used for optimal control.

The brake pressure generator described here is, in particular, a module which is connected to hydraulic units which pass on the wheel brakes individually actuated with the brake force generator. The brake force generator can also be referred to as a brake pressure generator or a pressure generator. The brake force generator is (as already stated) an automated or autonomous brake force generator, which can be integrated in an autonomous system for operating the motor vehicle or in a “by wire” system.

The plunger system with the at least one chamber is usually a piston system in which a piston can be moved within the chambers in order to increase or decrease the volume of the chambers. Several chambers can be arranged one behind the other along an axis and can be operated (in particular pressed) together in the plunger system. The plunger system usually has a push rod which extends through at least one of the chambers. There is then preferably at least one chamber partition which separates several chambers from one another and the push rod is movably sealed in the chamber partition. A chamber through which the push rod runs can also be referred to as a “push rod chamber”. A pressure circuit of a brake system that is connected to such a chamber can be referred to as a “pressure rod circuit”.

The brake drive is preferably an electric drive motor, which usually generates a rotational movement which is converted into a linear movement via a spindle drive.

The regulator is a type of control device that receives a braking request from a higher-level control device or pedal and, taking into account the actual pressure recorded by the pressure sensor, generates a particularly suitable control signal for the brake drive. The braking request can be in the form of an (electronic) braking signal.

The brake force generator is particularly advantageous if the pressure sensor has a time resolution rate of less than 1 ms [milliseconds], preferably less than 0.2 ms and particularly preferably less than 0.1 ms.

With such a pressure sensor with a very fine temporal resolution, particularly fast regulation is possible with the aid of the controller. The controller is preferably designed so that it can process the corresponding signals from the pressure sensor at a correspondingly high speed.

The braking force generator is also advantageous if it has at least two chambers, with at least one pressure sensor being arranged on each chamber.

In a further advantageous embodiment variant, the braking force generator has at least two chambers, a pressure sensor being arranged on only one of these chambers.

If only one pressure sensor is provided for two or more chambers, then the chambers are preferably connected to one another in such a way that pressure equalization takes place between the chambers and the values recorded with only one pressure sensor can be used to obtain a pressure signal that is representative of both chambers is.

As already described above, the braking request in step a) is preferably received by a superordinate unit (superordinate control device and / or brake pedal). The actual pressure is received in step b) by the pressure sensor already described above.

The method is particularly advantageous if in step b) an actual pressure gradient over time is received or determined in addition to an actual pressure.

Such an actual pressure gradient can be calculated in the control device (and possibly also in a unit upstream of the control device) from the change in the actual pressure over time.

The method is also particularly advantageous if a calculated control signal is calculated in step c) in such a way that an upper limit for an actual pressure gradient over time is specified.

Specifying such an upper limit has technical reasons in particular because it normally makes no sense to use the controller to specify control signals for the brake drive that are intended to cause changes in the actual pressure that exceed a permissible level.

In addition, the method is particularly advantageous if a calculated control signal is calculated in step c) in such a way that an upper limit is specified for the actual pressure.

Actual pressures above a threshold are usually not possible or sensible because they would inevitably lead to the wheel brakes being blocked. The system is preferably designed in such a way that such actual pressures are not requested at all, that is to say that no control signals are determined in step c) which could request such actual pressures.

The method is preferably carried out with a braking force generator described.

A braking system with a braking force generator described is also particularly preferred here.

The braking force generator described here, the possible control strategy and appropriately set up braking systems make it possible to recognize the critical load change independently of data from the ESP but with the help of a highly sampled pressure sensor and to regulate the electromechanical actuator based on pressure in order to prevent further pressure oscillations. In this way, large vibration amplitudes that put a strain on the hardware can be avoided and the pressure control for an ABS system can be more harmonious. This prevents negative influences on the braking distance.

With the method described and the braking force generator described, it is possible to identify the critical load change at an early stage independently of data from an ESP system. Pressure-based control of the electromechanical actuator avoids large vibration amplitudes that put a strain on the hardware and guarantees better ABS pressure control.

The braking force generator described, the method described and the braking system described are particularly suitable for highly automated braking systems or as purely autonomous braking systems. Such brake systems preferably manage completely without the operation of a brake pedal by a user. The described braking force generator and the described method can, however, also be operated with a “by-wire” connected brake pedal, ie with a brake system which is operated by a user, but which has an electronic “by-wire” signal transmission from the described to the braking force generator . The brake force generator, the method and the brake system can, however, also be part of a brake system that also enables manual or conventional operation (for example, using a brake pedal). The pressure generator, the method and the braking system are particularly suitable for highly automated or even autonomous driving.

The described braking force generator with the pressure sensor and the described method can detect a critical (and undesired) load change in the hydraulic system during braking at the time of the deviation from the brake pressure to the actual pressure, in particular independently of data from an ESP system or the ABS system. Data from the ESP system or the ABS system primarily consider the effect of braking, namely in the case of the ESP system usually positive or negative accelerations of the vehicle (for example yaw rates) or in the case of the ABS system the locking of the vehicle's wheels . In order to accelerate the regulation further - if further acceleration is necessary - a pressure gradient can be extrapolated from the last available measured values in order to detect the deviation even earlier. This can also be realized within the framework of the method described.

The braking force generator described here and the method described here are particularly suitable for increased requirements, such as those that occur in the case of ABS control, for example. Here the rigidity of the brake system (of the entire hydraulic system) is suddenly increased by switching the valves As a result, there will be a pressure peak or a very rapid and strong deviation from the target pressure in the chambers of the plunger system, which will be detected very quickly by the pressure sensor.

• 1: ein klassisches Bremssystem,
• 2: ein vollautonomes Bremssystem,
• 3: ein kombiniertes Bremssystem,
• 4: einen typischen Bremsdruckverlauf,
• 5: eine Regelstrategie, und
• 6: einen mit Hilfe des beschriebenen Verfahrens verbesserten Bremsdruckverlauf.

The pressure generator, the brake system and the method are explained in more detail below with reference to the figures. It should be pointed out that the figures show only preferred exemplary embodiments to which the disclosure is not limited here. Show it:

• 1 : a classic braking system,
• 2 : a fully autonomous braking system,
• 3 : a combined braking system,
• 4th : a typical brake pressure curve,
• 5 : a control strategy, and
• 6th : a brake pressure curve improved with the aid of the method described.

1 , 2 and 3 show different braking systems 31 which are to be explained together here as far as they have common components. On differences between the braking systems 31 according to the individual figures is indicated.

The braking systems 31 each have a braking force generator 12 , 13 which is used to generate the initial braking force and via which the braking process can ultimately be triggered. The initial braking force is provided as pressure in hydraulic lines and applied to the individual wheel brakes 9 transfer. The hydraulic fluid required for this comes from a fluid supply container 11 , which is a reservoir of hydraulic fluids for the braking system 31 ready.

In a conventional motor vehicle for which the brake systems shown here 31 is provided, there are four wheel brakes 9 (one wheel brake for each wheel 9 ), each paired together to a hydraulic unit 22nd are connected, preferably each wheel brakes 9 from diagonally opposite wheels to a hydraulic unit 22nd are connected. The hydraulic units 22nd each include a high pressure switching valve 26th through which to the wheel brakes 9 flowing hydraulic fluid can be controlled as well as a pressure regulating valve 27 over what hydraulic fluid from the wheel brakes 9 can flow away. With the high pressure switching valves 26th and the pump 29 can the pressure on the wheel brakes 9 increase. With the pressure regulating valves 27 can the pressure on the wheel brakes 9 adjusted and reduced again. Between the hydraulic units 22nd and the wheel brakes 9 are then each still controllable inlet valves 24 and exhaust valves 25th for the individual wheel brakes 9 arranged. With the inlet valves 24 can be the pressure on the individual wheel brakes 9 individually limited and increased again up to the system pressure. With the exhaust valves 25th can be the pressure on the individual wheel brakes 9 can be reduced individually. The inlet valves 24 and the exhaust valves 25th enable, for example, individual control of the individual wheel brakes 9 for ESP maneuvers or ABS maneuvers. The hydraulic units 22nd each also include a low-pressure accumulator 23 in which of the wheel brakes 9 drained hydraulic fluid can be temporarily stored. The hydraulic fluid from the low-pressure accumulators 23 can with pumps 29 driven by a pump drive 30th are driven, are pressed again and the hydraulic units 22nd to build up brake pressure on the wheel brakes 9 then be made available again.

The variant according to 1 shows schematically a classic braking system 31 with a manual brake force generator 12 . The brake pressure is set with a brake pedal shown here as an example 16 in chambers 15th a plunger system 14th generated. A braking request 1 (this means a specification of a certain braking force) acts directly on the brake pedal.

The variant according to 2 shows schematically an automatically or automatically operated braking system 31 , in which the braking force with an automatic braking force generator 13 is built. This automatic braking force generator 13 also has a plunger system 14th with at least one chamber 15th , preferably with several chambers 15th (particularly preferred with two chambers 15th ), to build up the brake pressure. However, this is not done with the help of a brake pedal 16 generated, but with the help of a brake drive 17th , which is from a control signal 33 is controlled. According to the variant embodiment described here, 33 does not directly correspond to a braking request 1 as would usually be the case if the brake drive 17th would be controlled in the same way as that according to 1 illustrated brake pedal 16 , but the control signal 33 is controlled by a special regulator 19th or higher-level system. The braking request 1 is first to the controller 19th to hand over. The regulator 19th received to generate the control signal 33 except for the braking request 1 another actual pressure 2 , which from a pressure sensor 18th it is determined what the pressure in the chambers 15th of the plunger system 14th of the automatic braking force generator 13 records. That in the 3 shown braking system 31 is intended in particular for use in fully automated or fully autonomous vehicles, where manual access from a brake pedal to the brake system 31 no longer occurs, but a braking request 1 "Only" as a signal and not is transmitted mechanically. This in 2 The brake system shown is atypical in that it only has one chamber 15th exists. In order to obtain redundancy here, plunger systems are normally used in motor vehicles without additional braking force generators 14th with two chambers 15th required.

3 shows a combined braking system 31 , which has both a manual brake force generator 12 like him in 1 is shown as well as an automatic braking force generator 13 like him in 2 shown is combined with each other. Both braking force generators 12 , 13 are each via connection valves 28 to the hydraulic units 22nd connectable or from the hydraulic units 22nd separable. So it can be decided whether the braking force with the manual braking force generator 12 or with the automatic braking force generator 13 should be generated. A brake pressure simulator is also shown here as an example 21st , which can be used to the user of a motor vehicle with such a braking system 31 simulate a braking force. Such a brake pressure simulator 21st can on a brake pedal 16 be connected and is used to give the user a realistic braking feeling when there is no direct mechanical active relationship between the brake pedal and the brake pressure generated, because a brake pressure is "only" transmitted as a signal.

Embodiments of the present invention provide a multi-circuit, hydraulically closed brake system without mechanical and / or hydraulic access by the driver, in particular for a highly automated or autonomous vehicle, and a corresponding operating method, with the pressure generators used acting on all wheel brakes through the hydraulic connection via the hydraulic unit of the vehicle.

The in 2 and in 3 Brake drive shown 17th is usually an engine. For controlling this motor, for example, the motor current and the motor speed are relevant variables. In the case of emergency braking maneuvers in particular, the brake drive must 17th have a very high dynamic. This means that the brake drive 17th must be able to react very quickly to brake pressure requests. The pressure sensor signal relating to the actual pressure 2 from the pressure sensor 18th is therefore preferably read in at high frequency and into the controller 19th also evaluated at high frequency.

The usually occurring situation from which the braking force generator described here and the operating method described here become relevant is shown in 4th shown. This diagram is on the pressure axis 3 over the timeline 4th a braking request 1 plotted as it is usually specified by a user (or a system for autonomous / automated) driving. There is also an actual pressure 2 which up to a first deviation 34 (which is defined for example by a certain threshold) the braking request 1 exactly follows. The actual pressure increases from this threshold 2 usually in relation to the brake pressure 1 way too strong.

This phenomenon is associated with the in 5 the control strategy shown. In 5 is a brake pressure specification in the upper area 20th shown, for example, an ABS controller 35 includes, which a braking request 1 pretends, this usually takes place in that a brake pressure model pressure 40 (an ideal brake pressure determined with the help of an electronic model) is specified from which the brake request is made 1 is determined. This braking request 1 becomes the controller shown in the lower area 19th to hand over. The regulator 19th serves to control the brake drive, which is also shown schematically here 17th . The core element of the controller is addition 39 in which the one with the pressure sensor 18th measured actual pressure 2 and the desire to brake 1 are added to each other (or subtracted from each other) to form a control difference 41 to determine which of the regulator 19th to control the brake drive 17th can be used. The regulator 19th preferably comprises the sub-modules position control 36 (to check the current position of the brake drive 17th ), the speed control 37 (to check the current speed of the brake drive 17th ) as well as the current control 38 (to check the current brake drive 17th provided drive current). These three units can each receive (additional) input variables from the brake drive 17th get an ideal control of the drive 17th to achieve so that the actual pressure 2 as exactly as possible to the braking requirement 1 follows.

With normal partial braking, your pressure sensor value (actual pressure 2 measured with the pressure sensor 18th ) follow the nominal driver brake request (curve before the in 4th shown deviation 35 ).

The situation that arises with the braking force generator described and the method described when ABS control takes place is shown in FIG 6th clearly shown. That in the 6th The example shown also applies to the case of an ESP regulation.

In the 6th is the definition of the target pressure 43 as a control variable in the ABS maneuver using the procedure described here and using the one described here. In 6th three phases A, B and C of an ABS braking process with a braking force generator described are shown as an example. At the beginning of phase A, the pressure is monitored and the actual pressure measured by the pressure sensor 2 corresponds to the braking request. This is in the upper part of the diagram on the pressure axis 3 over the timeline 4th applied.

At a point in time at the transition from phase A to phase B or shortly before this transition, the described controller with the described pressure sensor detects the deviation 34 . Such a deviation can be caused, for example, by inlet valves, outlet valves, high-pressure switching valves or pressure regulating valves of a brake system. When such valves are closed, the rigidity of the hydraulic system changes suddenly.

From this point in time, there is a particular tendency for wheel brakes to apply with great braking force, so that the wheels tend to lock. Due to the fact that the usual sensors for monitoring the braking behavior in ESP or ABS control units only deliver signals when the braking effects on the acceleration behavior of the motor vehicle or on the braking effect of the brakes. This is the reason that a control unit for ESP or ABS only receives signals that can be used by a control system at the point in time of the transition from phase B to phase C. It is only from this point in time that the ESP control loop or the ABS control loop is closed because the ABS and ESP react much more slowly compared to the controller described here and compared to the method described here. In phase B, the actual pressure is increased further with a predefined (maximum) gradient in accordance with the driver brake request. However, this only happens up to a specified upper limit (for example a maximum of 180 bar). The predefined (maximum) gradient and the specified upper limit are permanently stored in the controller for the method described here.

From the point in time of the transition from phase B to phase C, the typical recurring fluctuation of the brake pressure occurs. This fluctuation is caused by control interventions by the ESP control unit or the ABS control unit. The corresponding target pressure 43 and the brake pressure model pressure specified by the ESP control unit or the ABS control unit are in the middle part of the 6th over the timeline 4th applied. In the lower part of the 6th the piston position of the plunger system which is set by the braking is shown, which predetermines or influences the volume of the chambers in the plunger system.

Claims (7)

A method for operating a brake force generator (13) for the automated generation of a brake pressure for a brake system (31) of a motor vehicle, comprising the following steps: a) receiving a braking request (1), b) receiving an actual pressure (2) from at least one pressure sensor (18) with which a pressure in at least one chamber (15) of a plunger system (14) is monitored, an actual pressure gradient over time also being received in addition to an actual pressure (2) or is determined c) Calculating a control signal (33) for controlling a brake drive (17) of the braking force generator (13) taking into account the braking request (1) and the actual pressure (2), a calculated control signal (33) being calculated so that an upper limit for a temporal actual pressure gradient is given, and d) Output of the control signal (33) to the brake drive (17) for adapting the brake pressure in the chamber (15). Method for operating a braking force generator (13) according to Claim 1 , a calculated control signal (33) being calculated in step c) in such a way that an upper limit for the actual pressure (2) is specified. Brake force generator (13) for the automated generation of hydraulic brake pressure for a brake system (31) of a motor vehicle, having a plunger system (14) with at least one chamber (15) for receiving and pressurizing hydraulic fluid and a brake drive (17) which is set up to to change the volume of the at least one chamber (15) of the plunger system (14) and thereby cause a pressure build-up, as well as with at least one pressure sensor (18) arranged on the at least one chamber (15) for measuring a pressure build-up in the at least one chamber ( 15) and for outputting a pressure value signal, as well as a controller (19) which is set up to carry out the method according to Claim 1 or 2 to control the brake drive (17) for a pressure build-up in response to an electronic braking request (1) and in response to an actual pressure (2) which is measured with the pressure sensor (18). Brake force generator (13) Claim 3 wherein the pressure sensor (18) has a temporal resolution rate of 1 ms [milliseconds], preferably less than 0.2 ms. Brake force generator (13) Claim 3 or 4th having at least two chambers (15), at least one pressure sensor (18) being arranged on each chamber (15). Brake force generator (13) Claim 3 or 4th , wherein having at least two chambers (15), a pressure sensor (18) being arranged on only one chamber (15). A braking system (31) for a motor vehicle comprising a braking force generator (13) according to one of the Claims 5 to 6th .

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