Method for reducing pressure peaks in a hydraulic brake system and corresponding brake system

Abstract

The invention relates to a method for reducing pressure peaks in a hydraulic brake system comprising an electrically operated pressure building device (5). According to the invention, a drive resistance variable, in particular a torque, of the pressure building device (5) is measured, a speed variable of the pressure building device (5) is measured, and a quotient of the drive resistance variable and the speed variable is calculated (201), the quotient (201) determined in this way is monitored for the occurrence of a jump, and in the case of a determined jump, the speed requirement of the pressure building device (5) is reduced and / or a hydraulic valve (6, 122) is actuated to achieve a pressure reduction.

Description

Technical Field

[0001] The present invention relates to a method for reducing pressure peaks in a hydraulic braking system including an electrically operated pressurizing device. Background Technology

[0002] In modern braking systems, pressure actuation in the hydraulic system is achieved via an electrically operated pressurizing device, independent of driver intervention. In so-called brake-by-wire systems, pressure actuation is also performed by an electrically operated pressurizing device, even with driver-triggered braking intervention. In many operating conditions, the pressurizing device operates closed valves at least briefly, thus operating a highly rigid system. This is, for example, if the wheel brake inlet valve suddenly closes while the pressurizing device is effectively delivering a volume of pressure. As a result, pressure spikes of hundreds of bar levels can occur within milliseconds due to the significant inertia of the pressurizing device, negatively impacting the lifespan of hydraulic components.

[0003] To avoid this type of pressure spike, it is known to evaluate data from the system pressure sensors and intervene in wheel pressure regulation in the event of excessive pressure. Because braking systems typically need to have high redundancy, in order to ensure reliable braking even in the event of partial system failure, braking systems usually utilize multiple control units that communicate with each other via interfaces. However, because this type of communication involves large time delays, the regulation operation occurs somewhat too late to reliably prevent pressure spikes. Summary of the Invention

[0004] Therefore, the object of the present invention is to provide a method that can prevent pressure peaks even in highly redundant braking systems.

[0005] This objective is achieved by the method described in claim 1 for reducing pressure peaks in a hydraulic braking system comprising an electrically operated pressurizing device. The driving resistance variable of the pressurizing device, particularly the torque, and the speed variable of the pressurizing device are measured. The quotient of these two measured values ​​(i.e., the driving resistance variable and the speed variable) is calculated. It has been shown that in the case of a sudden change in (the quotient), the two measured values ​​change in opposite directions, and this effect is greatly amplified by forming the quotient according to the invention. If a sudden change in the determined quotient is subsequently detected, the change is shown at a particularly early stage and is particularly clear. In the case of a determined sudden change, the speed requirement of the pressurizing device is reduced and / or the hydraulic valve is operated to achieve a pressure reduction. As a result, the pressure peak is effectively suppressed from the outset.

[0006] In a preferred embodiment of the invention, the pressurizing device is configured as a linear actuator. This is a pressure supply device that can be hydraulically connected to a wheel brake and has a pressure piston that can be moved into a pressure chamber by an electric motor to provide system pressure for actively building pressure in the wheel brake. Here, the electric motor is typically connected to the piston via a rotary / translational transmission mechanism. The rotational speed of the motor can be measured as a speed variable. For this purpose, a rotor position sensor of the pressurizing device can be used, for example. The applied torque can be determined, for example, based on the power consumption of the motor, or alternatively, it can be measured by a sensor provided for this purpose.

[0007] In another preferred embodiment of the invention, a jump is identified if the absolute value of the calculated quotient exceeds a first threshold. This type of evaluation can be implemented in a particularly simple manner and is especially advantageous in cases of relatively imprecise measurements or in cases of high-noise measurements.

[0008] In a particularly preferred embodiment of the invention, the first threshold is from 1 mNm / rpm to 2 mNm / rpm, preferably 1.5 mNm / rpm. Here, the speed variable is selected as rotational speed and measured in revolutions per minute (rpm). Torque is measured in millinewtons (mNm).

[0009] In another preferred embodiment of the invention, the time curve of the quotient is stored, and a jump is identified if the gradient (slope) of the quotient calculated in the stored curve exceeds a second threshold. Gradient monitoring can be used as an alternative to or supplement to absolute value monitoring. To improve the accuracy of the method, the calculated quotient can be smoothed. For this purpose, time averaging can be performed, for example.

[0010] In a particularly preferred embodiment of the invention, the second threshold is from 0.1 Nm / rpm*sec to 0.3 Nm / rpm*sec, particularly 0.15 Nm / rpm*sec.

[0011] In another preferred embodiment of the invention, a jump is identified if the curvature of the quotient calculated in the stored curve exceeds a third threshold. Accordingly, the second derivative of the quotient over time is formed and monitored. This type of monitoring can detect jumps and thus reliably detect anticipated pressure spikes at particularly early stages, especially in the case of accurate, well-smooth measurements.

[0012] In another preferred embodiment of the invention, the actuation of the hydraulic valve causes it to open at least partially. In this way, hydraulic volume or braking fluid can flow out through the hydraulic valve, resulting in a minimization of pressure peaks.

[0013] In another preferred embodiment of the invention, the control of the hydraulic valve is performed by the same control unit also used to regulate the pressurization device. Specifically, the system pressure sensor for the braking system is located on a different control unit, rather than on the same control unit as the controllers for the hydraulic valve and the pressurization device. In this way, delays caused by communication between different control units are avoided, and monitoring can be performed particularly quickly.

[0014] In another preferred embodiment of the invention, the hydraulic valve is arranged between the pressurizing device and the unpressurized brake fluid reservoir or pressure medium storage container. Specifically, the hydraulic valve is arranged directly between these components. In this way, pressure reduction can be achieved particularly quickly once a pressure peak is detected.

[0015] In another preferred embodiment of the invention, the hydraulic valve includes at least one inlet valve for the wheel brake of the braking system. Here, instead of simply opening the inlet valve, the control current of the inlet valve is reduced. For redundancy reasons, the inlet valve is a normally open valve. That is, current is supplied to the inlet valve to close it and hold it in the closed position. The pressure difference from the high pressure on the side facing the pressurizing device to the low pressure on the side facing the wheel brake attempts to open the valve. The closing current counteracts this force and holds the valve in the closed position. However, depending on the set closing current, there is hydraulic pressure, so that the inlet valve is no longer held in a sealed manner and hydraulic volume can pass through. The closing current of the inlet valve is then reduced: specifically reduced to a value that still keeps the hydraulic valve closed during normal operation, but allows hydraulic volume to pass through at pressure values ​​corresponding to pressure peaks (100 bar to 300 bar).

[0016] Furthermore, this objective is achieved by a braking system for a motor vehicle, which is configured to perform one of the methods described above.

[0017] Other features, advantages, and possible applications of the invention also arise from the following description and drawings of exemplary embodiments. All features described and / or illustrated are individually and in any combination, and independently of their summary in the claims or their reference thereto, which are part of the subject matter of the invention. Attached Figure Description

[0018] Figure 1 A braking system according to a first embodiment of the present invention is schematically shown.

[0019] Figure 2 schematically shown Figure 1 The electronic architecture of the braking system,

[0020] Figure 3 A braking system according to a second embodiment of the present invention is illustrated schematically.

[0021] Figure 4 Exemplary measurement values ​​of the quotient according to the present invention are shown.

[0022] Figure 5 It shows Figure 4 The average derivative of an exemplary measurement. Detailed Implementation

[0023] Figure 1 The braking system of the illustrated motor vehicle includes four hydraulically actuated wheel brakes 8a-8d. The braking system includes: a master cylinder 2, actuated by means of an operating pedal or brake pedal 1; a stroke simulator or simulation device 3, which interacts with the master cylinder 2; a pressure medium storage container 4, which is at atmospheric pressure; an electrically controlled pressurization device 5; and brake pressure modulation valves for each wheel, which, according to the example, are configured as inlet valves 6a-6d and outlet valves 7a-7d. Furthermore, the braking system includes an electronic control adjustment system 12, which includes multiple control units for operating the electrically actuated components of the braking system.

[0024] According to this example, wheel brake 8a is assigned to the left front wheel (FL), wheel brake 8b is assigned to the right front wheel (FR), wheel brake 8c is assigned to the left rear wheel (RL), and wheel brake 8d is assigned to the right rear wheel (RR).

[0025] The master cylinder 2 has a master cylinder piston 15 within the housing 16 that defines a hydraulic pressure chamber 17, and constitutes a single-circuit master cylinder. The pressure chamber 17 receives a return spring 9, which positions the piston 15 in the initial position when the master cylinder 2 is not actuated.

[0026] The pressure chamber 17 is first connected to the pressure medium storage container 4 via a radial orifice constructed in the piston 15 and a corresponding pressure balancing line 41, wherein the radial orifice can be closed by the relative movement of the piston 17 within the housing 16. Secondly, the pressure chamber 17 is connected to the brake supply line 13 via a hydraulic line section (also referred to as the first supply line) 22, the inlet ports of the inlet valves 6a-6d being connected to this brake supply line. The pressure chamber 17 of the brake master cylinder 2 is thus connected to all inlet valves 6a-6d.

[0027] In this embodiment, no valve is provided in the pressure balancing line 41 or in the connection between the pressure chamber 17 and the pressure medium storage container 4, in particular no electrically or hydraulically actuated valve is provided and no check valve is provided.

[0028] Alternatively, a diagnostic valve (particularly normally open) may be included in the pressure balancing line 41 or between the brake master cylinder 2 and the pressure medium storage container 4, preferably in parallel connection of a normally open diagnostic valve and a check valve that closes toward the pressure medium storage container 4.

[0029] An isolation valve 23 is arranged between the supply line 22 connected to the pressure chamber 17 and the brake supply line 13, or the pressure chamber 17 is connected to the brake supply line 13 via a first supply line 22 having the isolation valve 23. The isolation valve 23 is configured as an electrically actuated, preferably normally open, 2 / 2-way valve. The isolation valve 23 allows the hydraulic connection between the pressure chamber 17 and the brake supply line 13 to be severed.

[0030] The piston rod 24 couples the pivoting motion of the brake pedal 1 caused by pedal actuation to the translational motion of the brake master cylinder piston 15. The actuation stroke of the brake master cylinder piston is detected by a displacement sensor 25, which preferably has a redundant configuration. As a result, the corresponding piston stroke signal is a measure of the brake pedal actuation angle. It represents the braking demand of the vehicle driver.

[0031] A pressure sensor 20 connected to the first supply line 22 detects the pressure built up in the pressure chamber 17 due to the displacement of the piston 15. This pressure value can also be evaluated to characterize or determine the braking demand of the vehicle driver. Alternatively, a force sensor 20 can be used to determine the braking demand of the vehicle driver.

[0032] According to this example, the simulation device 3 has a hydraulic construction and is hydraulically connected to the brake master cylinder 2. The simulation device 3 mainly includes, for example, a simulator chamber 29, a simulator rear chamber 30, and a simulator piston 31 that separates the two chambers 29 and 30 from each other. The simulator piston 31 is supported on the housing by an elastic element 33 (e.g., a simulator spring), which is arranged in the simulator rear chamber 30 (which is dry according to this example). According to this example, the hydraulic simulator chamber 29 is connected to the pressure chamber 17 of the brake master cylinder 2 by means of a preferably electrically actuated, preferably normally closed simulator activation valve 32.

[0033] For the hydraulically actuated wheel brakes 8a-8d, the braking system or brake unit system includes inlet valves 6a-6d and outlet valves 7a-7d, which are hydraulically connected in pairs via a center port and connected to the wheel brakes 8a-8d. Check valves (not shown in detail) opening toward the brake supply line 13 are each connected in parallel to the inlet valves 6a-6d. The outlet ports of the outlet valves 7a-7d are connected to the pressure medium storage container 4 via a common return line 14.

[0034] The electrically controllable pressure supply device 5 is configured as a hydraulic cylinder / piston assembly (or a single-loop, electro-hydraulic actuator (linear actuator)), the piston 36 of which can be actuated by an electric motor 35, schematically indicated, and a rotary / translational transmission mechanism 39 connected between the two, also schematically shown. The piston 36 defines a single pressure space 37 for the pressure supply device 5. A rotor position sensor, schematically indicated only, for detecting the rotor position of the electric motor 35, is indicated by reference numeral 44. This can be used to assess the current rotational speed.

[0035] A section of pipeline (also referred to as the second supply line) 38 is connected to the pressure space 37 of the electrically controlled pressurizing device 5. The supply line 38 is connected to the brake supply line 13 via an electrically actuated, preferably normally closed, sequence valve 26. The sequence valve 26 allows the hydraulic connection between the pressure space 37 of the electrically controlled pressure supply device 5 and the brake supply line 13 (and thus the inlet ports of the inlet valves 6a-6d) to be opened and closed in a controlled manner.

[0036] The actuator pressure generated by the force exerted by piston 36 on the pressure medium enclosed in pressure space 37 is supplied to the second supply line 38. In "brake-by-wire" operation, particularly in the fault-free state of the braking system, supply line 38 is connected to brake supply line 13 via sequence valve 26. In this way, during normal braking, wheel brake pressure build-up and pressure reduction occur in all wheel brakes 8a-8d due to the forward and rearward movement of piston 36.

[0037] When the pressure is reduced by the rearward movement of the piston 36, the pressure medium that was previously moved from the pressure space 37 of the pressure supply device 5 to the wheel brakes 8a-8d flows back into the pressure space 37 in the same manner.

[0038] Alternatively, different wheel braking pressures can be easily set for individual wheels using inlet valves 6a-6d and outlet valves 7a-7d. When the corresponding pressure decreases, a portion of the pressure medium discharged through outlet valves 7a-7d flows into the pressure medium storage container 4 via return line 14.

[0039] With sequence valve 26 closed, pressure medium can be replenished into pressure space 37 by the retraction of piston 36. This is because the pressure medium can flow from container 4 and enter the actuator pressure space or pressure space 37 via line 42 having a check valve 53 that opens in the flow direction to actuator 5. According to this example, in the unacted state of piston 36, pressure space 37 is additionally connected to pressure medium storage container 4 via one or more suction ports. When piston 36 is (fully) actuated in actuation direction 27, this connection between pressure space 37 and pressure medium storage container 4 is broken.

[0040] In the brake supply line 13, an electrically actuated normally open circuit isolation valve 40 is arranged. The brake supply line 13 can be divided into a first line section 13a and a second line section 13b by means of this isolation valve. The first line section (via isolation valve 23) is connected to the brake master cylinder 2, and the second line section (via sequence valve 26) is connected to the pressure supply device 5. The first line section 13a is connected to the inlet valves 6a and 6b of the wheel brakes 8a and 8b, and the second line section 13b is connected to the inlet valves 6c and 6d of the wheel brakes 8c and 8d.

[0041] With the circuit isolation valve 40 open, the braking system is a single-circuit design. By closing the circuit isolation valve 40, the braking system, particularly when controlled in a suitable manner, can be divided or split into two braking circuits I and II. Here, in the first braking circuit I, the master cylinder 2 (via the isolation valve 23) is connected only to the inlet valves 6a and 6b of the wheel brakes 8a and 8b of the front axle VA, and in the second braking circuit II, the pressure supply device 5 (with the sequence valve 26 open) is connected only to the wheel brakes 8c and 8d of the rear axle HA.

[0042] With the circuit isolation valve 40 open, the inlet ports of all inlet valves 6a-6d can be supplied with pressure via the pressure supply line 13, which in the first operating type (e.g., "brake-by-wire" operating type) corresponds to the braking pressure provided by the pressure supply device 5. In the second operating type (e.g., in the no-current standby operating type), the brake supply line 13 can be loaded with the pressure of the pressure chamber 17 of the master cylinder 2.

[0043] The braking system advantageously includes a level measuring device 50 for determining the level of the pressure medium in the pressure medium storage container 4. Identification of loop separation achieved by means of the loop isolation valve 40 is advantageously performed via the level measuring device 50.

[0044] According to this example, the hydraulic components (i.e., brake master cylinder 2, simulation device 3, pressure supply device 5, valves 6a-6d, 7a-7d, 23, 26, 40 and 32, and the hydraulic connection including brake supply line 13) are arranged together in a (single) hydraulic control unit 60 (HCU). The hydraulic control unit 60 is configured with an electronic control unit (ECU) 12 having multiple control units. The hydraulic control unit 60 and the electronic control unit 12 are preferably configured as a single unit (HECU).

[0045] The braking system includes a pressure sensor 19 or a system pressure sensor for detecting the pressure supplied by the pressure supply device 5. Here, viewed from the pressure chamber 37 of the pressure supply device 5, the pressure sensor 19 is arranged downstream of the sequence valve 26.

[0046] Figure 2 It shows Figure 1 The braking system control system 12 includes two separate control units 45 and 46, each designed to control and regulate a portion of the braking system. As the controller herein named, the motor control unit includes a motor controller 47 that regulates the motor 49 of the pressurization device. In addition to the valve controller 48 named, the valve control device 46 includes electronics for reading the system pressure sensor 50. The two control units can communicate with each other via an interface. If a regulation operation dependent on data from the pressure sensor 50 is to be performed to avoid pressure spikes, communication must be performed between the two control units 46 and 47 to allow intervention in the motor controller 47. This type of communication results in a delay, which means that pressure spikes cannot be prevented quickly enough. According to the invention, this method can be performed only on the motor control unit 45.

[0047] Figure 3 A braking system according to another preferred embodiment is shown. The braking system includes three modules 70, 72, and 74, each including a separate control and adjustment unit 80, 82, or 84. Module 70 includes a master cylinder 2 configured as a tandem master cylinder having a main chamber 90 and a secondary chamber 92, and a simulator or simulation device 3. The main chamber 90 can be connected to the simulator chamber 29 in a line-controlled mode by means of a simulator activation valve 32. The two chambers 90 and 92 of the master cylinder can be hydraulically connected to a pressure medium storage container 4a. A partition wall 100 in this container ensures that the pressure medium can still be used for the other braking circuit even if one of the two braking circuits I and II connected to chambers 90 and 92 leaks. The control and adjustment unit 80 of module 80 is mainly used to control valve 32.

[0048] The braking system includes a driver brake request detection device comprising a pedal travel sensor 25 and a pressure sensor 20 for measuring the pressure in the master cylinder. A second module 72 with a control adjustment unit 82 includes a pressure supply device 5 and two sequence valves 26a, 26b, the pressure space 37 of which is hydraulically connected to the wheel brakes via these two sequence valves. Furthermore, the second module includes a rotor position sensor 44 and a pressure sensor 20 for measuring the pressure in the master chamber 90. In online control mode, the two chambers 90, 92 can be hydraulically disconnected from the wheel brakes via isolation valves 23a, 23b, resulting in the driver removing brake fluid from the master chamber 90 and into the simulator chamber 29 when the simulator activation valve 22 is open.

[0049] The pressure chamber 37 is hydraulically connected to the pressure medium storage container 4b, from which the braking medium can be replenished, wherein the pressure medium is prevented from flowing back from the pressure chamber 37 into the container 4b by a check valve 120.

[0050] If isolation valves 23a and 23b are closed during online operation and the hydraulic connection between the master cylinder 2 and the wheel brakes 8a-d is disconnected, the excess brake volume can be delivered to container 4b via line 124 and the opening of discharge valve 122.

[0051] An intermediate wall 130 is disposed in the pressure medium storage container 4b, which defines two separate chambers when the filling liquid level drops below the height of the intermediate wall 130. A control and regulation unit 82 is used to actuate the pressure supply device 5 and valves 26a, 26b, 23a, 23b, and 122.

[0052] The third module 74, with control and adjustment unit 84, includes inlet valves 6a-d and outlet valves 7a-d for assigning brakes to the wheels. Pumps 140 and 142 are provided in each brake circuit, and the pumps can be hydraulically connected to the pressure supply device via pump sequence valves 160 and 162 in the suction path, respectively.

[0053] The pressure that can be established by the corresponding pumps 140 and 142 can be set by means of the relief valves 150 and 153. If the pumps 140 and 142 deliver too much volume and the pressure rises, the valves 150 and 152 are opened, and the pressure in the pump chamber can still be regulated by the valves 150 and 152 and their flow rates.

[0054] Furthermore, low-pressure accumulators 164 and 166 are respectively provided in each of the two braking circuits. Check valves 168 and 170 respectively prevent the pressurized medium from flowing out of the delivery circuits of pumps 140 and 142 along the outlet valves 7a-d. Control and regulating unit 84 is used to actuate pumps 140 and 142 and valves 67a-d, 7a-d, 160, 162, 150, and 152. In addition, module 74 includes a system pressure sensor 19.

[0055] Two pressure medium storage containers 4a and 4b are hydraulically connected to a common pressure medium storage container 4.

[0056] In this braking system, pressure supply device 5 is used to provide system pressure, while pumps 140 and 142 are specifically used to regulate operation and assist in pressure establishment through pressure supply device 5.

[0057] The three control and regulation units 80, 82, and 84 are connected to each other on the signal side, especially via the CAN bus.

[0058] The method according to the invention can then be advantageously implemented on the second control unit 82. This method regulates the linear actuator 5 and therefore specifically includes data from the rotor position sensor 44. If the ECU 2 82 determines a sudden change in the quotient of torque and speed, it can specifically open the discharge valve 122, which is controlled on the same circuit board. Therefore, the occurrence of pressure peaks is responded to very quickly.

[0059] Figure 4 An example illustrates the ratio of measured torque to rotational speed in a linear actuator. During normal operation (the initial range of the measured value), the ratio fluctuates around 0.5 mNm / rpm. Once the inlet valve is suddenly closed, the ratio rises sharply and exceeds a first threshold of 1.5 mNm / rpm. The system then assumes a pressure peak and initiates appropriate countermeasures.

[0060] Figure 5 The evaluation of the gradient 203 of the quotient is shown. The data is obtained through analysis of... Figure 4 The quotient is calculated by differentiation and then averaged over time. During normal operation, these values ​​fluctuate below the second threshold of 204. Once the inlet valve is closed, the gradient rapidly increases and exceeds the second threshold of 204, and the corresponding countermeasures are activated.

[0061] Therefore, the method according to the invention ensures that pressure peaks are reliably avoided even in redundant braking systems where the controller is divided into multiple control units, and thus extends the service life of hydraulic components.

[0062] List of reference numerals in the attached diagram:

[0063] 1. Brake pedal

[0064] 2 Brake master cylinder

[0065] 3. Simulation device

[0066] 4. Pressure medium storage container

[0067] 5. Pressurization device

[0068] 6a to d inlet valves

[0069] 7a to d outlet valves

[0070] 8a to d wheel brakes

[0071] 9. Return spring

[0072] 12 Control System

[0073] 13 Brake supply lines

[0074] 14 Return line

[0075] 16. Shell

[0076] 17 Pressure Chamber

[0077] 19 System pressure sensor

[0078] 20 Master cylinder pressure sensor

[0079] 22 First Supply Pipeline

[0080] 23 Isolation Valve

[0081] 24 Piston rod

[0082] 25 Displacement Sensors

[0083] 26 Sequence valve

[0084] 29 Simulator Chambers

[0085] 30 Simulator Rear Chamber

[0086] 31 Simulator Pistons

[0087] 32 Simulator Enable Valve

[0088] 33 Elastic elements

[0089] 35 Piston

[0090] 36 motors

[0091] 37 Pressure Space

[0092] 38 Supply lines

[0093] 39 Rotary / Translational Transmission Mechanism

[0094] 40-loop isolation valve

[0095] 41 Pressure balancing pipeline

[0096] 42 pipelines

[0097] 44 Rotor position sensor

[0098] 45 Motor control unit

[0099] 46 Valve Control Unit

[0100] 47 Motor Controller

[0101] 48 Valve Controller

[0102] 49 motors

[0103] 50 System pressure sensor module

[0104] 70 Module 1

[0105] 72 Module Two

[0106] 74 Module 3

[0107] 80 First Control Unit

[0108] 82 Second Control Unit

[0109] 84 Third Control Unit

[0110] 90 main chamber

[0111] 92 Secondary chambers

[0112] 120 Check Valve

[0113] 122 Discharge Valve

[0114] 124 pipeline

[0115] 130 Intermediate Wall

[0116] 140 First Pump

[0117] 142 Second Pump

[0118] 150 First relief valve

[0119] 152 Second relief valve

[0120] 160 First pump sequence valve

[0121] 162 Second pump sequence valve

[0122] 164 First Low-Voltage Accumulator

[0123] 166 Second Low-Voltage Accumulator

[0124] 168 First check valve

[0125] 170 Second check valve

[0126] 201 Torque / Speed

[0127] 202 First Threshold

[0128] 203 The derivative of the quotient

[0129] 204 Second Threshold

Claims

1. A method for reducing pressure peaks in a hydraulic braking system including an electrically operated pressurizing device (5), characterized in that, Measure the driving resistance variable of the pressurizing device (5), measure the speed variable of the pressurizing device (5), calculate the quotient (201) of the driving resistance variable and the speed variable, monitor whether the determined quotient (201) has a jump, and if a jump is found, reduce the speed requirement of the pressurizing device (5) and / or operate a hydraulic valve (6, 122) to reduce the pressure.

2. The method as described in claim 1, characterized in that, The pressurizing device (5) is configured as a linear actuator.

3. The method as described in claim 1 or 2, characterized in that, If the absolute value of the calculated quotient (201) exceeds the first threshold (202), a jump is identified.

4. The method as described in claim 3, characterized in that, The first threshold (202) is 1 mNm / rpm to 2 mNm / rpm.

5. The method as described in claim 1 or 2, characterized in that, The time curve of the quotient (201) is stored, wherein a jump is identified if the gradient (203) of the quotient (201) calculated in the stored curve exceeds a second threshold (204).

6. The method as described in claim 5, characterized in that, The second threshold (204) is 0.1 Nm / rpm. sec to 0.3 Nm / rpm sec.

7. The method as described in claim 1 or 2, characterized in that, The time curve of the quotient (201) is stored, wherein a jump is identified if the curvature of the quotient (201) calculated in the stored curve exceeds a third threshold.

8. The method as described in claim 1 or 2, characterized in that, The aforementioned operation of the hydraulic valve (122) causes it to open at least partially.

9. The method as described in claim 1 or 2, characterized in that, The control of the hydraulic valve (122) is performed by the same control unit that is also used to regulate the pressurization device.

10. The method as described in claim 1 or 2, characterized in that, The hydraulic valve (122) is arranged between the pressurizing device (5) and the unpressurized brake fluid reservoir (4).

11. The method as described in claim 1 or 2, characterized in that, The hydraulic valve includes at least one inlet valve (6) of the wheel brake (8) of the braking system, wherein the control current of the inlet valve (6) is reduced.

12. The method as described in claim 1 or 2, characterized in that, The driving resistance variable is torque.

13. A braking system for a motor vehicle, characterized in that, The braking system is configured to perform the method as described in any one of claims 1 to 12.

Images