WO2018149558A1

WO2018149558A1 - Method for operating a braking system, and braking system

Info

Publication number: WO2018149558A1
Application number: PCT/EP2018/050503
Authority: WO
Inventors: Jürgen Böhm; Paul Linhoff
Original assignee: Continental Teves Ag & Co. Ohg
Priority date: 2017-02-15
Filing date: 2018-01-10
Publication date: 2018-08-23
Also published as: DE102017202361A1

Abstract

The invention relates to a method for detecting a driver's wish to brake (PSoll) in a braking system comprising: at least two electrically operated wheel brakes (42-48); a simulator (14) for simulating a conventional brake pedal feel; a brake pedal (6) for actuating the simulator (14); a pedal travel sensor for measuring the pedal travel (XPedal) of the brake pedal (6); wherein the pedal travel (XPedal) is used to detect the driver's wish to brake (PSoll), and wherein the pedal foot force (FPedal) is measured and is used when the driver's wish to brake (PSoll, FSP) is detected, and wherein the detection of the driver's wish to brake comprises determining a driver brake request (PSoll ,FWE), wherein the driver brake request is detected using the maximum of the driver brake request (PSoll ,FWE) and at least one additional brake request (PSoll ,F_func1, PSol l ,F_func2).

Description

Method for operating a brake system and brake system

The invention relates to a method for driver braking request detection in a brake system, which comprises at least two electrically actuated wheel brakes, a simulator for simulating a conventional brake pedal feeling, a brake pedal for operating the simulator, a pedal travel sensor for measuring the pedal travel of the brake pedal, wherein for detecting the driver's brake wish the pedal travel is used, and wherein the pedal foot force is measured and used in the detection of the driver's brake request, and wherein the

Driver brake request capture the determination of a

Driver brake request includes. It also relates to a brake system.

In automotive technology, "brake-by-Wi re" -Bremsanlagen are becoming more widespread.Such brake systems often include an operable in addition to the driver operable master cylinder an electrically ("by-Wi re") controllable pressure supply device by means of which in the operating mode " Brake-by-Wi re "an actuation of the wheel brakes takes place.

In these brake systems, in particular electro-hydraulic brake systems with the operating mode "brake-by-wire", is the

Driver decoupled from the direct access to the brakes. When the pedal is actuated, a pedal decoupling unit and a simulator are usually actuated, whereby the driver's braking intention is detected by a sensor system. The Pedal Simulator is designed to give the driver as familiar a brake pedal feel as possible. The he took braking demand leads to the determination of a desired braking torque, from which then the sol lbremsdruck is determined for the brakes. The brake pressure is then actively built up by a pressure supply device in the brakes.

The actual braking therefore takes place by actively building up pressure in the brake circuits with the aid of a pressure supply unit. direction, which is controlled by a control unit. Due to the hydraulic decoupling of the brake pedal actuation from the pressure build-up, I have many functionalities such as ABS, ESC, TCS, hang-on assistance, etc. in such brake systems. comfortable for the driver.

The pressure supply device in brake systems described above is also used as an actuator or. designated hydraulic actuator. In particular, actuators are designed as linear actuators, in which a piston is axially displaced into a hydraulic pressure chamber for pressure build-up, which is built in series with a rotational-translation gear. The angle of the motor shaft of an electric motor is converted by the rotation-translation gear in an axial displacement of the piston.

From DE 10 2013 204 778 AI a "Brake-by-wire" -Bremsanlage for motor vehicles is known, which a brake pedal operable tandem master cylinder, the pressure chambers connected in each case via an electrically betätable Trennventi 1 separable with a brake circuit with two wheel brakes are, with the master cylinder hydraulically connected, on and off switchable simulation device, and an electrically controllable pressure supply device, which is formed by a cylinder-piston arrangement with a hydraulic pressure chamber whose piston is slidable by an electromechanical actuator includes, wherein the pressure-supplying device is connected via two eiektri sch actuatable Zuschaltventile with the intake valves of the wheel brakes.

In such brake systems is usually a mechanical or. Hydraulic fallback provided by the driver by muscle force on actuation of the brake pedal, the vehicle slow down or. can bring to a halt when the

During normal operation by a pedal decoupling unit, the hydraulic decoupling described above between brake pedal actuation and brake pressure build-up, this decoupling is canceled in the fallback so that the driver can move brake fluid directly into the brake circuits. In the case of recirculation is switched when no pressure build-up is possible with the help of the pressure-providing device.

In normal operation, the driver actuates a pedal imu lator in such a power brake system, this pedal operation is detected by pedal sensors and a corresponding Drucksol 1wert is determined for the linear actuator to actuation of the wheel brakes. A movement of the linear actuator from its rest position forward into the pressure chamber shifts brake fluid volume from the linear actuator via the open valves in the wheel brakes and thus increases a pressure build-up. In the opposite case, the movement of the linear actuator back in the direction of its rest position leads to a pressure reduction in the wheel brakes. The setting of a required system pressure is carried out with the aid of a suitable pressure regulator resp. a suitable pressure control system, in which, for example, the pressure regulator, a speed controller is subordinate. For the demand-driven and precise setting of the required pressures, a pressure-volume characteristic is stored in the brake system, which maps the ratio of volume and pressure so that the associated pressure can be determined for each volume and vice versa.

Upon actuation of the brake pedal to request a brake pressure, the driver is no longer directly connected to the brake system, but operates a pedal simulator having a suitable pedal characteristics, so that the driver from a sufficiently accurate dosage of the requested braking request is made possible. This pedal operation is detected by pedal sensors and determined therefrom a brake request of the driver corresponding Drucksol Iwert for the linear actuator to actuate the wheel brakes. It will be understood for this purpose usually the pedal position X i and the _Peda, generated by the force applied by the driver's pedal force, in the simulator pressure using a pressure sensor (Psimuiator), said Pe ^¬ dalposition and if necessary for security reasons. also the simulator pressure determined redundantly become . Thus, for the driver request detection, two physically independent information are available for the driver's control representing the driver's brake request for sol I value generation of the required brake force boosting by means of the linear actuator. Result and

Output size of a in the control and regulation unit or. ECU to be provided function unit "driver request detection" is determined on the basis of the driver pedal actuation set value for the boost pressure (target pressure in the linear actuator).

If a braking request is present, a movement of the linear actuator from its rest position to the front shifts the brake fluid volume from the linear actuator via the open valves to the wheel brakes and thus causes a build-up of pressure. In the opposite case, the movement of the linear actuator back in the direction of its rest position leads to a reduction in pressure in the wheel brakes. Because of the design-related inertia of the linear actuator, it must first be accelerated in order to carry out this movement, so that there is a difference between the setting of a print request on the basis of the brake request and its setting or setting. Implementation gives a certain dynamic delay. This can be considerable depending on the design of the linear actuator and the requirement for the dynamics of the braking process. Especially with schnei len pedal operations and the associated high dynamic pressure requirements, it is therefore important to capture the driver's desire as early as possible.

The invention is therefore an object of the invention to provide a method by which the driver's braking request is possible I detected early and accurate. In addition, a brake system should be specified, which allows early and precise driver braking request detection.

With regard to the method, this object is achieved in that the driver brake request detection is given by the maximum of the driver brake request and at least one additional brake request. Advantageous embodiments of the invention are the subject of the dependent claims.

The invention is based on the consideration that in brake-by-wire mode, the precise and possibly early detection of the driver's braking request is very important in order to be able to perform braking operations with active pressure build-up in a good manner

To be able to perform driver braking. In particular during emergency braking, early detection is important.

As has now been recognized, it is possible to detect the driver's braking desire as early and precisely as possible, by measuring how much the driver presses or presses the brake pedal. how much he pushes it. This means that the driver's pedal footing is measured. Particularly in simulators designed to not allow detection of a driver or simulator pressure signal, as is the case, for example, in a mechanical pedal simulator, the driver's foot force provides a useful signal for detecting the desired braking because a pressure signal is not available stands . By taking into account additional braking requirements, the driver 's braking request can be detected more quickly, for example by changing the response of the brake pedal or brake pedal. an actuation of the brake pedal, which could indicate an emergency braking, be parameterized by a Zusatzbremsanforderung. These supplemental brake requirements may advantageously account for the fact that the pedal operation by the driver is initially recognizable in the signal of a sensor measuring foot pedal 1.

A first additional brake request is preferably set to a value zero, if no pressure request is detected, and is set to a constant value as soon as a pedal actuation by the driver is reliably detected on the basis of the pedal force signal.

The first additional brake request is preferably set to zero when, during a predetermined time interval, based on the Pedal way no pedal operation is detected, a maximum request time is expired fen or the brake pedal is released again. The pedal operation is detected in this case when the pedal travel exceeds a predetermined pedal travel threshold value for a predetermined number of scanning steps.

Preferably, a second additional brake request is set to a value nul 1, unless a pressure request is detected and is set to a constant value as soon as a pedal actuation by the driver is reliably detected on the basis of the pedal force signal, the engine 1 is a predetermined pedal speed threshold value. A reliable recognition of the pedal operation is preferably carried out when during a predetermined period of time, the pedal force is greater than a predetermined pedal kraftschwel lenwert, said pedal force threshold lenwert is set so that it can be exceeded only at the fast pedal speed values faster than mentioned pedal speed threshold are.

This force threshold, represented by means of the pedal force threshold value, is preferably selected to be so high that it can only be exceeded in the event of a rapid pedal actuation, which then leads to the initiation of emergency braking.

The second Zusatzbremsanforderungs function is preferably set to nul 1, if during a predetermined time interval based on the pedal travel no pedal actuation is detected or a maximum request time has expired.

The driver brake request is preferably given by the product of a weighting factor having a first function, which depends on the pedal travel and / or the pedal speed, and a second contribution, which is given by the product of a weighting factor with a function that depends on the pedal kra ft , In a first preferred embodiment form, the brake system is designed to be electrohydraulic, wherein the wheel brakes are designed hydraulically, and wherein an electrohydraulic pressure supply device for brake pressure buildup at least one wheel brake, in which Hi 1 fe of an electric motor, a pressure piston is displaceable in a hydraulic pressure chamber.

Advantageously, in this case, the simulator on a hydraulic simulator simulator chamber, in which upon actuation of the brake pedal pressure medium from the main brake Zyl Indians is promoted.

In a further preferred embodiment, the brake system is designed to be electromechanical, the wheel brakes being designed as electromechanical wheel brakes.

Advantageously, the simulator is mechanically formed. This means that a pressure signal is not available to detect the driver's braking request. Therefore, the pedal travel signal and the pedal pedal signal are available for detecting the driver's braking request.

The invention also encompasses a method for a brake system, which comprises both hydraulic and electromechanical wheel brakes. For example, a brake circuit can be hydraulically designed, the other brake circuit electromechanical.

The term "electrically actuable wheel brakes" preferably means that the corresponding wheel brake for setting a desired one of a control and regulating unit

Wheel brake pressure resp. Radbremssol Idruckes can be electrically controlled. This applies to both hydraulic and electromechanical wheel brakes. The driver brake request or. Print requirements refer to

Within the scope of the application to an electrohydraulically designed brake system, a desired pressure or pressure is achieved. a print request for a target pressure. In the case of an electromechanically designed brake system, the driver brake request or denote. the pressure request a request for the application force with which the brake pads are pressed against the brake disc. The application force required to realize the driver's brake request is preferably determined separately for the front axle and the rear axle.

That the pedal foot power is used includes in particular their consideration in the calculation of the driver's brake request. It is effectively an input in a module that calculates the driver's brake.

The foot pedal force is preferably measured by means of a sensor or. Kra ftelementes, which is installed, for example, on the piston rod of the brake pedal module. As a result, taking into account the PedalüberSetzung, the force is detected with the driver via the brake pedal the pedal simulator operated. The driver brake request detection preferably includes the determination of a driver brake request, in which the pedal eg and the pedal foot force verv / ends.

With regard to the brake system, the abovementioned object is achieved according to the invention by means of a method described above. In particular, the brake system comprises a control and regulation unit, in which the method is implemented in hardware and / or software. In a first preferred embodiment, the brake system is formed electro-hydraulically with at least two, preferably four hydraulically ausgebi ldeten wheel brakes.

In a second embodiment, the brake system is electromechanically designed with at least two electromechanically designed wheel brakes. The advantages of the invention are, in particular, that the safety of the driver is increased by an early and precise detection of the driver's braking request in connection with additional braking requirements.

A game of the invention will be explained with reference to a drawing. Therein show in a highly schematic representation: FIG. 1 shows a brake system in a preferred embodiment;

FIG. 2 is a flow chart of a method in a first preferred embodiment; and

FIG. 3 is a flowchart of a method in a second preferred embodiment.

Identical parts are provided with the same reference numerals in all figures.

In FIG. 1 is an exemplary embodiment of a brake system 2 according to the invention shown. The brake system comprises a central brake cylinder 10 which can be actuated by an actuating or brake pedal 6, a simulation device 14 cooperating with the main brake cylinder 10, a pressure medium reservoir 18 assigned to the main brake cylinder 10 and under atmospheric pressure, an electrically controllable pressure supply device 20, which is formed by a cylinder-piston arrangement with a hydraulic pressure chamber 26 whose piston 32 is slidable by an electromechanical actuator, an electrically controllable pressure modulating ion device for setting wheel-individual

Brake pressures and an electronic control unit 40th

The unspecified Druckmoduiat ionsei direction comprises in accordance with hydraulically actuated wheel brakes 42, 44, 46, 48 and each operable wheel brake 42 to 48 an inlet valve 50, 52, 54, 56 and an exhaust valve 60, 62, 64, 66 which are interconnected in pairs via center ports hydraulically and connected to the wheel brakes 42 to 48. The input ports of the intake valves 50 to 56 are supplied by brake circuit supply lines 70, 72 with pressures derived in a "brake-by-wire" mode from a system pressure in a connected to the pressure chamber 26 of the pressure supply device 20 system pressure line 80. The brakes 42, 44 are connected to a first brake circuit 84, the brakes 46, 48 to a second brake circuit 88 hydraulically connected.

In each case, a check valve 1 90, 92, 94, 96 opening toward the brake circuit supply lines 70, 72 is connected in parallel to the inlet valves 50 to 56. In a fallback living mode, the brake circuit supply lines 70, 72 are acted upon by hydraulic lines 100, 102 with the pressures of the brake fluid from pressure chambers 120, 122 of the master cylinder 10. The output ports of the exhaust valves 60 to 66 are connected via a return line 130 to the pressure medium reservoir 18.

The main brake cylinder in the 10 we is in a housing 136 two successively arranged pistons 140, 142 which limit the hydraulic pressure chambers 120, 122. The pressure chambers 120, 122 are on the one hand in the piston 140, 142 formed radial bores and corresponding pressure equalization lines 150, 152 with the pressure fluid reservoir 18 in connection, the compounds by a relative movement of the pistons 140, 42 in the housing 136 can be shut off. The pressure chambers 120, 122 are on the other hand by means of the hydraulic i see lines 100, 102 with the aforementioned brake circuit supply lines 70, 72 in connection.

In the pressure equalization line 150 is a normally open Venti 1 160 included. The pressure chambers 120, 122 take unspecified return springs on which the pistons 140, 142 at position unopposed master cylinder 10 in a starting position. A piston rod 166 on which preferably the pedal force, taking into account the pedal translation or. a signal representing the pedal force is measured, the pivotal movement of the brake pedal 6 is coupled to the translational movement of the first master brake cylinder 140 or 140 as a result of a pedal actuation. PrimärkoIbens whose actuation path is detected by a, preferably redundant executed, displacement sensor 170. As a result, the corresponding piston travel signal is a measure of the brake pedal actuation angle. It represents a braking request of the driver.

In the connected to the pressure chambers 120, 122 line sections 100, 102 each have a separating valve 180, 182 arranged, which is ausgebi as an electrically operable, vorzugswei se normally open, 2/2 way valve. Through the isolation valves 180, 182, the hydraulic connection between see the

Pressure chambers 120, 122 of the main brake cyl inders 10 and the brake circuit supply lines 70, 72 are shut off. A pressure sensor 188 connected to the line section 102 detects the pressure built up in the pressure chamber 122 by displacing the second piston 142.

The simulation device 14 can be hydraulically coupled to the main brake cylinder 10 and, by way of example, essentially comprises a simulator chamber 190, a simulator spring chamber 194, and a simulator cylinder 198 separating the two chambers 190, 194. The simulator piston 198 is supported by a Simulator spring chamber 194 arranged elastic element (eg., A spring), which is vorteiihaf- terly biased on the housing 136 from. The simulator chamber 190 is connected by means of an electrically operable simulator valve 200 with the first pressure chamber 120 of the main brake cyl inders 10. Upon specification of a pedal force and open simulator valve 200, pressure medium flows from the master brake cylinder pressure chamber 120 into the simulator chamber 190. A check valve 210 arranged hydraulically in antiparallel to the simulator valve 1 200 makes it possible to independently of the switching state Simulatorventi ls 200 a largely unhindered backflow of the pressure medium from the simulator chamber 190 to the master cylinder pressure chamber 120. Other imple mentation and connections of the simulation device to the master cylinder 10 are conceivable.

The electrically controllable pressure supply device 20 is as a hydraulic Zyl inder-piston assembly or. a single-circuit electrohydraulic actuator is formed whose / which pressure piston 32, which delimits the pressure chamber 26, of a schematically indicated electric motor 220 with the interposition of a ebenfal ls schematically illustrated rotational translation gear, which is preferably designed as a ball screw (KGT) operable. One of the detection of the rotor position of the electric motor 220 serving, only schematically indicated rotor position sensor is designated by the reference numeral 226. In addition, a temperature sensor 228 may be used to sense the temperature of the motor winding.

The actuator pressure generated by the force of the piston 32 on the trapped in the pressure chamber 26 pressure medium actuator pressure is fed into the system pressure line 80 and with a preferably redundant pressure sensor 230 he summarizes. With open pressure switching valves 240, 242, the pressure medium enters the wheel brakes 42 to 48 for their actuation. By pushing forward and backward of the piston 32, when the pressure-relief valves 240, 242 are open, during normal braking in the "brake-by-wire" mode, a wheel brake pressure buildup and dismantling takes place for all the wheel brakes 42 to 48.

When pressure is reduced, the pressure medium previously displaced from the pressure chamber 26 into the wheel brakes 42 to 48 flows back into the pressure chamber 26 in the same way. On the other hand, during braking, wheel brake pressures that are different with the individual intake and exhaust valves 50 through 56, 60 through 66, respectively, flow (for example in the case of anti-skid control

(ABS control)) of the discharged via the exhaust valves 60 to 66 Pressure medium content in the pressure medium reservoir 18 and is thus initially no longer available to the pressure supply device 20 for actuating the wheel brakes 42 to 48.

In an alternative embodiment form, the brake system has four wheel brakes, in each of which in one, preferably floating caliper 254 two brake elements are arranged, on which j ewei ls is arranged with a brake pad, between which a brake disc is arranged. A pressure-already tel lungseinrichtung, which is designed as a linear actuator and dedicated in the j ewei 1 igen wheel brake builds brake pressure, has a hydraulic pressure chamber in which a pressure piston is moved as needed. In this case, the rotational movement of the motor shaft of an electric motor is converted by a rotation-translation gear in a translational movement of the pressure piston. For detecting the piston position, a preferably redundantly designed rotor blade sensor is provided.

In a further alternative embodiment form can be provided instead of a Druckbereit stel ment device an electromechanical shear linear actuator, wherein the rotarische movement of the motor shaft of an electric motor by a rotational-translation gear in a translational movement of a piston which is directly connected to a brake pad is converted , Instead of a brake pressure is then seen in this electromechanical wheel brake actuation by applying a predetermined clamping force with the

Brake pads are pressed against the brake disc. The brake system then preferably comprises two, more preferably four electromechanical wheel brakes of the type described.

In the control and regulation unit 40, a method, which is described below, implemented software and / or hardware.

A method in a first preferred embodiment is shown in FIG. 2 shown. In a block 280, a first driver brake request is calculated. For this purpose, the pedal travel X _Peda i is used as input. In a hydraulic simulator, a pressure signal from the simulator pressure can also be used in a known manner as a starting variable in the usual way. However, this signal is hereby replaced by the pedal foot force F _ped ai. The driver brake desires Psoii, PWE is calculated to

Psoll, FWE ⁼ Psoll, X + Psoll, F ⁼ λχ * fX (X _P edal V _Pe dal) + λρ * fp (F _Pe dal)

Where:

Psoii, x: Pedalwegbas-based target pressure component;

P _SOII , _F : pedal force-based target pressure component;

f x: Brake pressure value calculated based on pedal travel and if necessary. Pedal speed;

fP: Brake pressure setpoint function calculated based on the pedal force

λχ, λ _Ρ : weighting factors (= 0 ... 1) for f _x resp. f _P The weighting factors can be used, for example, to make a dependent of the driving vehicle speed V _Kfz lowering the brake pressure request at slow speeds. Another application is the different weighting of the Soildruckanteile P _K oii.x and Psoii, FZ. B. as a function of the pedal travel. Thus, it can be achieved, for example, that in the region of small pedal travel the brake pressure P _SOII , _{FE is determined} in detail on the basis of the pedal travel, while in the region of large pedal travel the target brake pressure P _SOII , _{FE is} predominantly pedal-based. The special definition and parameter selection for the brake pressure requirement by the driver is heavily vehicle and manufacturer 1 and thus application specific.

An initiated by the driver emergency braking by a quick pedal operation is here wesentl I based on

Evaluation of the pedal entry speed V _Peda i recognized, which is calculated in block 280 from the pedal travel X _Ped ai. If this signal exceeds a predefined threshold, due to the recognized emergency braking situation for P _SOII , _{FE set} the maximum target pressure.

In a block 282, another driver brake request is desired. a first additional brake request P _SOLL , _F funci calculated. Input ^¬ sizes for block 282 are the pedal stroke Xp _eda i and the pedal force

Fpedal ·

While in a slow operation of the brake pedal in wesentl only the static forces of the pedal simulator unit (spring force, frictional force) are overcome, the force to accelerate the Pedalsimulatoreinhei t in the signal F _Peda i is also measurable in a quick operation, which is characterized by a pronounced depending on Betätigungsgeschwindigkei t pronounced power surge.

To improve the response in the normal braking function, especially for large brake lining clearance, the Zusatzdruckan request Ps ₀ ii, F_funci from the value 0 (no

Pressure request) to a, preferably constant, pressure sol lwert P,> 0 bar set as soon as a pedal operation by the driver is reliably detected by the signal F _pedal . The starting point for this secure detection is initially the unactuated state (F _Pe dai = 0 and Xp _e dai = 0). A pedal actuation is then recognized if, in several successive controller loops, F _Peda i> Fi, where F; is a predetermined threshold. The threshold Fi should be set so that it differs significantly from the force in the unactuated state and is below the static forces mentioned above.

An activated pressure _request P _SOII , _{F f} u _nc i = Pi is withdrawn again if, after the end of a time Τ ·, no pedal actuation in the path signal (Xp _eda i> 0) can be established, a maximum request time T _{2 has} expired or

Brake pedal is released again. The determination of T ₂ is carried out so that after this time in each case a brake pressure _request P _SOII , _FE > 0 is expected. The preferred constant Pressure value P-, is set so that it leads to overcoming the pad clearance and applying the pads. A typical value for this is therefore P; = 1 ... 2 bar. To support and respond faster to a driver initiated by a schnei le pedal actuation emergency braking is further proposed that the pressure requirement

P _SO II, F func2 is set from the value 0 (no pressure request) to a maximum pressure setpoint P ₂ = Ps ₀ n, Max as soon as a corresponding rapid pedal actuation by the driver is reliably detected on the basis of the signal F _Pe . The starting point here too is the unactuated state (F _Peda i = 0 and X _Peda i = 0). The fast pedaling required for activation is recognized when Fp _eda i> F ₂ in several consecutive controller _loops , threshold F ₂ being set so that it can only be exceeded by those values F _Peda i that are due to give the above-mentioned power increase in a schnei len pedal operation. The exact definition of the threshold F ₂ depends on the design layout and design of the Pe dal simulator unit and is also anwendungsspezi ^¬ fish.

An activated pressure request P _SO II, F func2 = P ₂ = Psoii, Max is withdrawn again if after a time 3 no pedal operation in the path signal (X _Pe dai> 0) can be determined or a maximum request time T _{4 has} expired. In this case, the determination of Tj is carried out in such a way that in each case an emergency braking situation recognized by evaluation of the pedal entry speed V _Pe dai has been treated by predetermining P _SO II, F _W E = Ps _o ii, Max. After the time T ₄ has elapsed, this function is inactive in every case and can only be activated again if the unoperated state of the brake pedal has been determined by F _Peda i = 0 and X _Pe dai = 0. As a further deactivation condition, it can be monitored whether the brake pedal is released again before the time T _{4 has} expired. Since the value of T _{4 is} relatively small due to the above-mentioned determination, this condition essentially serves 1 to, a For example, due to disturbances in the force signal caused Fehlaus solution by P _SOII , _F func2 = Psoii, max back before the expiration of T ₄ again. The two in FIG. 2 marked printing requirements

P _S oii, F funci and P _S oii, F func2 represent Zusatzbremsanforderun ^¬ conditions, which take into account to a particular extent that the pedal operation by the driver first in the signal F _Peda i is recognizable. The driver brake request P _So ii now results in a block 290 due to a maximum value formation of the three Bremsdruckan requirements described above:

Psoll = MAX (Psoll, FWE, Psoll, F func / Psoll, F func2, 0). Due to the combination of these three pressure requirements by a maximum value formation act the two additional _{braking requirements detected} by the signal F _Ped ai pedal operation only until the normal driver _{request detection} (P _SOII , _FWE ) is the decisive for the resulting braking request (Psoii) signal. While the additional braking requirements in the pedal operation lead to an earlier reaction of the linear actuator and thus contribute to an improvement of the response, they are disabled when releasing the pedal and he t 0. In a brake system with electromechanical wheel brakes results for the respective wheel brake the resulting Specified value for the application force F _Sp , with which the brake pads are pressed against the brake disc, from the thus calculated brake request P _So ii (which in this case represents a pure arithmetic operation) by multiplication with a scaling factor A _sc , this factor A _sc is dependent on the special imple mentation and / or arrangement in the vehicle of the electromechanical wheel brake:

F _Sp = Asc * Psoii

In FIG. FIG. 3 shows a further preferred embodiment of the method, which is advantageously used in particular in a brake system 2 with a mechanical pedal simulator. Of the Driver's request is determined as in the prior art in block 280 from the Pedalweginformation and learns no further changes. The driver foot traffic information F _Peda i is only used in blocks 282, 284 for the two foot force-based additional brake requirements, or respectively. Functionality should. F f and UIlCl should be used F f unc2.

Claims

claims

A method for driver braking request detection (Psoii) i ⁿ a brake system, which includes

• at least two electrically operated wheel brakes

(42-48);

A simulator (14) for simulating a conventional brake pedal feel;

• a brake pedal (6) for operating the simulator (14);

A pedal travel sensor for measuring the pedal travel (X _Peda i) of the brake pedal (6),

wherein the pedal travel (X _Peda i) is used to detect the driver brake request (Psoii), and wherein the pedal foot force (F _Peda i) is measured and in the detection of the

Fahrerbremswunsches (Psoii _/ F _SP ) is used, and wherein the driver braking request detection, the determination of a

Driver braking request (P _S0 II, _FE ) includes,

characterized in that

the driver brake request detection is given by the maximum of the driver brake request (P _S0 II, _FE ) and at least one additional brake request

(P _S oii, F_funci, Psoii, F_f _U n _C 2) ·

The method of claim 1, wherein a first additional brake request (P _SO II, _F funci) is set to a value zero, if no pressure request is detected, and is set to a constant value as soon as a Pedalbe ^¬ actuation is reliably detected by the driver.

3. The method of claim 2, wherein the first additional brake request (P _S0 II, _F funci) is set to zero, if during a predetermined time interval no Pedalbe ^¬ actuation is detected, a maximum request time has expired or the brake pedal is released again. Method according to one of claims 1 to 3, wherein a second auxiliary braking request (P _S0II, _F f _U nc2) is set to a value of zero if no print request is detected, and is set to a constant value as soon as a pedal operation by the driver sure which is faster than a preset pedal speed threshold.

The method of claim 4, wherein the second additional brake request function (P _S0II , _F f _U nc2) is set to zero, if during a predetermined time interval, no pedal operation is detected or a maximum request ^¬ ment time has expired.

Method according to one of claims 1 to 5, wherein in the driver brake request (P _SOII , _FE ), the pedal travel (X _Ped ai) and the pedal foot force (F _Peda i) are used.

The method of claim 6, wherein the driver's braking request (P _soii, _FE) is given by the product of a weighting- ^¬ tung factor _(λ χ) having a first function which is dependent on the pedal travel (X _Peda i) and / or the pedal speed (dXpe _d ai / dt), and a second contribution given by the product of a weighting factor (λ _Ρ ) with a

Function that depends on the pedal force (F _Peda i).

Method according to one of claims 1 to 7, wherein the wheel brakes (42-48) are hydraulically formed, and wherein an electro-hydraulic pressure supply device (20) for braking pressure build-up of at least one wheel brake (42-48), in which by means of an electric motor (220, 290 ) a pressure piston (32, 286), in a hydraulic pressure chamber (26, 282) is displaceable.

9. The method of claim 8, wherein the simulator (14) has a hydraulic simulator chamber (190), in which upon actuation of the brake pedal (6) pressure medium from a with the brake pedal (6) operable master cylinder (10) is promoted.

10. The method according to any one of claims 1 to 7, wherein the

Wheel brakes (42-48) are designed as electromechanical wheel brakes.

11. The method of claim 10, wherein the simulator (14) is mechanically formed.

12. brake system (2) with means (40) for carrying out a method according to one of the preceding claims.

13. Brake system (2) according to claim 12, which comprises at least two hydraulic wheel brakes (42-48).

14. Brake system (2) according to claim 12, which comprises at least two electromechanical wheel brakes.