DE102021211457A1 - Brake system for a motor vehicle and method for operating a brake system for a motor vehicle - Google Patents

Abstract

Brake system (1) for a motor vehicle, comprising: - a master brake cylinder (3) which can be actuated by a brake pedal (2), - a simulation device (4) which can be hydraulically connected to the master brake cylinder (3) by a simulator release valve (15), and - a pressure medium reservoir (9) under atmospheric pressure for storing a hydraulic pressure medium, wherein the pressure medium reservoir (9) can be switched on hydraulically by a simulator characterization valve (5) of the simulation device (4) and a method for operating the brake system (1), wherein the pressure medium reservoir ( 9) is switched on hydraulically by the simulator characterization valve (5) of the simulation device (4).

Description

The invention relates to a brake system for a motor vehicle according to the preamble of the independent device claim and a method for operating a brake system for a motor vehicle according to the preamble of the independent method claim.

From the WO 2011/029812 A1 discloses a braking system for actuating four hydraulically actuable wheel brakes, with an electrically controllable pressure modulation device with individual wheel inlet and outlet valves, a master brake cylinder that can be actuated by a brake pedal and is hydraulically connected to the pressure modulation device, a simulation device that is hydraulically connected to the master brake cylinder, a electrically controllable pressure supply device, which is also hydraulically connected to the pressure modulation device, and a pressure medium reservoir under atmospheric pressure. The brake system has a modular structure with a first module, which includes the master brake cylinder and the simulation device, a second module, which is formed by the pressure supply device, and a third module with, among other things, the inlet and outlet valves. The modules are assembled into a unit, which is assigned to the pressure medium reservoir.

From the DE 10 2014 212 536 A1 a brake system for actuating four hydraulically actuated wheel brakes is known, in which an electrically controllable pressure modulation device with wheel-specific inlet and outlet valves and an electrically controllable pressure supply device, which is hydraulically connected to the pressure modulation device. The pressure modulation device with its inlet and outlet valves represents a first structural electrohydraulic control and regulation unit.

The brake system also includes a master brake cylinder, a simulation device that can be connected hydraulically thereto and has an associated simulator release valve, with a check valve being connected antiparallel to the simulator release valve. The master brake cylinder, the simulation device and the pressure supply device are structurally combined to form a second structural electrohydraulic control and regulation unit, to which a pressure medium reservoir is assigned. The first and second electrohydraulic control and regulation units are connected to one another via hydraulic and electrical connecting lines.

The pressure medium reservoir feeds the master brake cylinder and the pressure supply device with hydraulic pressure medium via respective outlets and also has a return connection for the hydraulic pressure medium, which flows back from the wheel brakes via the outlet valves of the pressure modulation device.

The simulation device is hydraulically connected to a first chamber of the master brake cylinder. An effect of the simulation device on the master brake cylinder can be switched on or off by means of the simulator release valve arranged in between. When a pedal force is specified and the simulator release valve is activated, pressure medium flows from the master brake cylinder into the simulation device. This simulates a braking feel on the brake pedal. The check valve, which is arranged hydraulically antiparallel to the simulator release valve, enables the pressure medium to flow back largely unhindered from the simulation device to the first chamber of the master brake cylinder, regardless of the switching state of the simulator release valve.

As can be seen from this prior art, the master brake cylinder and the simulation device are located together in one structural unit. In principle, the installation space for this unit in the motor vehicle is tight. Therefore, this unit must be kept as small and light as possible. This unit is also intended for different vehicle types. If more braking power is required for a particular type of vehicle, or if a hard brake feel is desired, a larger brake master cylinder is usually fitted to the unit. However, this also means that a simulation device adapted to it must then be installed. There is usually no more space for these, which is why a smaller simulation device is used. This has the disadvantage that the entire pedal travel cannot be mapped due to the simulation device being too small.

In addition, according to customer requirements, different simulation devices with different characteristics must be available. This means that the unit on which it is based must always be adapted to the various simulation facilities. This increases the development effort and costs.

It is the object of the invention to provide a brake system for a motor vehicle in which the characteristics of a simulation device can be adjusted, and to provide a method for operating a brake system for a motor vehicle which enables an adjustable characteristic of a simulation device.

The object on which the invention is based is achieved with the features of the independent patent claims. Preferred embodiments emerge from the dependent claims.

• - einen Hauptbremszylinder, welcher durch ein Bremspedal betätigbar ist,
• - eine Simulationseinrichtung, welche hydraulisch durch ein Simulatorfreigabeventil dem Hauptbremszylinder zuschaltbar ist, und
• - einen unter Atmosphärendruck stehenden Druckmittelvorratsbehälter zur Bevorratung eines hydraulischen Druckmittels,

wobei der Druckmittelvorratsbehälter hydraulisch durch ein Simulatorcharakterisierungsventil der Simulationseinrichtung zuschaltbar ist.According to the invention, a brake system for a motor vehicle is provided, comprising:

• - a master brake cylinder, which can be actuated by a brake pedal,
• - A simulation device which can be switched on hydraulically by a simulator release valve to the master brake cylinder, and
• - a pressure medium reservoir under atmospheric pressure for storing a hydraulic pressure medium,

wherein the pressure medium reservoir can be switched on hydraulically by a simulator characterization valve of the simulation device.

The characteristic of the simulation device is advantageously changed by connecting the pressure medium reservoir to the simulation device. If the pressure medium reservoir is hydraulically connected to the simulation device, the pressure medium can flow from this into the pressure medium reservoir. Due to the reduced pressure medium, a lower pressure force acts in the simulation device, so that it has a different characteristic than that to which it was initially set. As a result, the characteristics of the simulation device can be changed during operation of the brake system. Consequently, different characteristics for different vehicle types can be achieved with one and the same simulation device, without a special simulation device having to be installed in the corresponding electro-hydraulic open-loop and closed-loop control unit for each vehicle type.

The simulation device preferably includes a simulator pressure chamber, to which the pressure medium reservoir is hydraulically connected when the simulator characterization valve is open. The master brake cylinder is preferably also hydraulically connected to the simulator pressure chamber when the simulator release valve is open. The simulator pressure chamber, in which the hydraulic pressure medium acts on a simulator piston, is connected to the pressure medium reservoir and the master brake cylinder. The simulator pressure chamber can be connected to the master brake cylinder via a connection and a pressure medium line and to the pressure medium reservoir via a connection and another pressure medium line. However, the simulator pressure chamber can also be connected to the master brake cylinder and the pressure medium reservoir via a single connection and a dividing pressure medium line. Essentially, a fluidic connection between the simulator release valve and the simulation device to the pressure medium reservoir must be possible, so that a hydraulic pressure prevailing there can be reduced to the pressure medium reservoir.

According to a preferred embodiment, the simulator characterization valve is designed as an analog switching valve. The simulator characterization valve is preferably designed to be closed when de-energized. In order to switch on the pressure medium reservoir of the simulation device, it is advisable to use a switching valve that is closed when de-energized. The simulator characterization valve is thus mainly closed and is opened when required.

According to an alternative embodiment, the simulator characterization valve is designed as a proportional valve. It is thus possible with the proportional valve to determine or change a volume flow of the hydraulic pressure medium from the simulation device into the pressure medium reservoir. A specific opening or flow cross-section can be set with the proportional valve. The opening cross section influences the volume or amount of pressure medium that flows into the pressure medium reservoir per period of time. Contrary to the analogue switchover valve, the proportional valve assumes a constant switching position. With the proportional valve, it is even possible to change the characteristics of the simulation device during a brake actuation by varying the opening cross section during this time.

According to a further preferred embodiment, the simulation device has a different characteristic curve when the simulator characterization valve is open than when the simulator characterization valve is closed. When the simulator characterization valve is closed, the simulation device has its usual effect, which follows a predetermined characteristic curve. If, on the other hand, the simulator characterization valve is open, the simulation device has a characteristic curve with a longer or softer course.

• - einen Hauptbremszylinder, welcher durch ein Bremspedal betätigbar ist,
• - eine Simulationseinrichtung, welche hydraulisch durch ein Simulatorfreigabeventil dem Hauptbremszylinder zuschaltbar ist, und
• - einen unter Atmosphärendruck stehenden Druckmittelvorratsbehälter zur Bevorratung eines hydraulischen Druckmittels,

wobei der Druckmittelvorratsbehälter hydraulisch durch ein Simulatorcharakterisierungsventil der Simulationseinrichtung zugeschaltet wird.The invention also relates to a method for operating a brake system for a motor vehicle, the brake system comprising the following:

• - a master brake cylinder, which can be actuated by a brake pedal,
• - A simulation device which can be switched on hydraulically by a simulator release valve to the master brake cylinder, and
• - a pressure medium reservoir under atmospheric pressure for storing a hydraulic pressure medium,

wherein the pressure medium reservoir is switched on hydraulically by a simulator characterization valve of the simulation device.

The method has the advantage that when the pressure medium reservoir is switched on, the simulation device follows a different characteristic than that to which it is initially set. Because the pressure medium flows into the pressure medium reservoir, the pressure force in the simulation device is reduced. This changes the characteristics of the simulation device during operation of the brake system.

When the brake pedal is actuated, a displacement signal and a pressure signal are preferably evaluated to form a force-displacement curve and this force-displacement curve is compared with a predetermined force-displacement characteristic, and if a deviation is determined, the simulator characterization valve is activated . If the brake pedal is pressed, a displacement sensor detects a displacement of the master brake cylinder piston. At the same time, a pressure sensor records the hydraulic pressure built up by the master brake cylinder piston. The signals from these two sensors are evaluated in an electronic control and regulation unit and processed into a force-displacement curve. At the same time, this currently running force-displacement curve is compared with a predetermined force-displacement characteristic. When the simulator characterization valve is closed, the current force-displacement curve runs in the manner in which the simulation device is initially set. However, if a different characteristic of the simulation device is desired, then the predetermined force-displacement characteristic differs from the actual force-displacement curve. Accordingly, if the current force-displacement curve deviates from the predetermined force-displacement characteristic, the simulator characterization valve is actuated or opened accordingly. The outflow of the hydraulic pressure medium into the pressure medium reservoir then causes the current force-displacement curve to approach the predetermined force-displacement characteristic.

According to a preferred embodiment, the simulator characterization valve is a proportional valve, with a volumetric flow from the simulation device to the pressure medium reservoir being set by the proportional valve when the brake pedal is actuated. A characteristic of the simulation device can be set with the aid of the proportional valve, which is in a continuous range between the closed and open simulator characterization valve. When the simulator characterization valve is fully open, the simulation device has a completely different effect than when the simulator characterization valve is closed. However, the proportional valve can also be used to set an effect that is within this range. In addition, the effect of the simulation device can also be changed by changing the volume flow during actuation of the brake pedal.

Further preferred embodiments of the invention result from the following description of an exemplary embodiment with reference to the figures.

• 1 eine beispielsgemäße Bremsanlage mit einem Simulatorcharakterisierungsventil, und
• 2 ein Kraft-Weg-Diagramm mit einer beispielsgemäßen Kraft-Weg-Kennlinie.

Show it:

• 1 an exemplary brake system with a simulator characterization valve, and
• 2 a force-displacement diagram with an exemplary force-displacement characteristic.

In the 1 shows the circuit diagram of an exemplary brake system 1 for a motor vehicle, which is operated with a hydraulic pressure medium. Brake system 1 comprises a brake master cylinder 3, which can be actuated by means of a brake pedal 2, a simulation device 4 which is hydraulically connected and interacts with the brake master cylinder 3, an electrically controllable pressure supply device 6 for generating hydraulic pressure and a pressure modulation device 7 for setting wheel-specific brake pressures on four wheel brakes 8a-8d, and a pressure medium reservoir 9.

In the present case, wheel brake 8a is assigned to the left front wheel VL, wheel brake 8b to the right front wheel VR, wheel brake 8c to the left rear wheel HL and wheel brake 8d to the right rear wheel HR, with left and right front wheels VL and VR being assigned to the front axle VA and left and right rear wheels HL and HR are assigned to the rear axle HA.

Simulation device 4, pressure supply device 6 and pressure modulation device 7 are combined to form a first electrohydraulic open-loop and closed-loop control unit 10, for example. Master brake cylinder 3 represents a second electrohydraulic control and regulation unit 11. First and second electrohydraulic control and regulation units 10 and 11 are individual structural units and can be arranged separately from one another in the motor vehicle.

Master brake cylinder 3 includes a master brake cylinder piston 32 which is coupled to brake pedal 2 via a piston rod 31 . At a Actuation of the brake pedal 2 by the vehicle operator moves the master cylinder piston 32 axially in a housing 35 . Housing 35 delimits a pressure chamber 34 with master brake cylinder piston 32, in which hydraulic pressure medium is located, whereby a single-circuit master brake cylinder 3 is represented. In addition, a restoring spring 33 is accommodated in the housing 35, which moves the unactuated master brake cylinder piston 32 into its initial position. Housing 35 is represented by the structural unit of the second electro-hydraulic control and regulation unit 11 .

A travel sensor 53 is provided on master brake cylinder 3 , which detects the actuation travel of master brake cylinder piston 32 . Displacement sensor 53 is arranged in the second electro-hydraulic control and regulation unit 11 . Travel sensor 53 is preferably a magnetic field sensor and detects a change in the magnetic field originating from master brake cylinder piston 32 for travel determination. The measured distance represents the driver's braking request. In addition, a first pressure sensor 55 is provided, which detects the pressure built up in the pressure chamber 34 of the master brake cylinder 3 as a result of a displacement of the master brake cylinder piston 32 . First pressure sensor 55 is arranged in first electrohydraulic control and regulation unit 10 .

Simulation device 4 includes a simulator piston 42 located in a simulator housing 41, which separates a simulator pressure chamber 45 and a simulator rear chamber 44 from one another. Simulator pressure chamber 45 is set up to hold hydraulic pressure medium and simulator rear chamber 44 is dry. Simulator pressure chamber 45 can be connected hydraulically to master brake cylinder 3 via a simulator release valve 15 . The hydraulic pressure medium presses on the simulator piston 42, which is supported on a simulator spring 43 arranged in the rear chamber 44 of the simulator.

The pressure modulation device 7 arranged in the first electrohydraulic control and regulating unit 10 comprises an inlet valve 18a-18d and an outlet valve 19a-19d for each hydraulically actuatable wheel brake 8a-8d, which are hydraulically interconnected in pairs via central connections and connected to wheel brakes 8a-8d. A check valve opening toward the brake supply line is connected in parallel to each of the inlet valves 18a-18d. Inlet valves 18a-18d of pressure modulator device 7 can be switched on or off from master brake cylinder 3 by a separating valve 14. Furthermore, a circuit separating valve 16 is provided, which can separate the inlet valves 18c and 18d of the rear axle HA from the inlet valves 18a and 18b of the front axle VA. Thus, when the circuit separating valve 16 is closed, no hydraulic connection is possible from the master brake cylinder 3 to the wheel brakes 8c and 8d of the rear axle HA. If, on the other hand, circuit separating valve 16 is open, these wheel brakes are also subjected to hydraulic pressure from master brake cylinder 3 .

Electrically controllable pressure supply device 6 is designed as a linear actuator. An electric motor 61 drives a piston 63 with the interposition of a rotation-translation gear 62, which pressurizes the hydraulic pressure medium in a pressure chamber 64. Pressure supply device 6 can be switched on via a hydraulic connection to the inlet valves 18a-d of pressure modulator device 7 in order to build up braking pressure at wheel brakes 8a-8d. For the precise control of piston 63, the rotor position of electric motor 61 is detected with a rotor position sensor 54. A sequence valve 17 is provided downstream of the pressure supply device 6 . When the sequence valve 17 is open, the wheel brakes 8a-8d are supplied with hydraulic pressure medium from the pressure supply device 6 via the pressure modulator device 7. A second pressure sensor 56 is arranged downstream of the switching valve 17 and upstream of the pressure modulation device 7 to measure the pressure provided by the pressure supply device 6 . The second pressure sensor 56 is arranged in the first electro-hydraulic open-loop and closed-loop control unit 10 .

Pressure medium reservoir 9 is assigned to the first electrohydraulic control and regulation unit 10 . Pressure medium reservoir 9 is under atmospheric pressure and serves as a store and as a compensating tank for the hydraulic pressure medium. Pressure medium reservoir 9 includes a level sensor 57. Level sensor 57 is used to detect the level or also functions as a level warning device. If necessary, this sensor can also be equipped with one, two or more switching states. Pressure medium reservoir 9 comprises a first connection 58 and a second connection 59, to each of which a pressure medium line is connected in order to supply the components of brake system 1 with the pressure medium and thus also pressure medium from the components can flow back into pressure medium reservoir 9. For this purpose, the pressure medium reservoir 9 is placed on the first electro-hydraulic control and regulation unit 10 so that the hydraulic pressure medium flows downwards.

A first electronic control and regulation unit 12 and a second electronic control and regulation unit 13 are also assigned to the first electrohydraulic control and regulation unit 10 . First electronic control and regulation unit 12 is used to control pressure modulation devices Device 7, ie the electrically operable inlet valves 18a-18b and the electrically operable outlet valves 19a-19d. The measurement signals from the first pressure sensor 55 and from the second pressure sensor 56 and from the level sensor 57 are preferably processed in the first electronic control and regulation unit 12 . Second electronic control and regulation unit 13 is used to control pressure supply device 6 and switching valves 14, 15, 16 and 17. The measurement signals from displacement sensor 53 and rotational position sensor 54 are preferably processed in second electronic control and regulation unit 13.

First, a first pressure medium line 21 leads from the master brake cylinder 3 to the simulator release valve 15 . A second pressure medium line 22 leads from the simulator release valve 15 to the simulation device 4 . Second pressure medium line 22 comprises a first line section 22a and a second line section 22b. First line section 22a leads to simulator release valve 15. Second line section 22b leads to an input side of an exemplary simulator characterization valve 5. From an output side of simulator characterization valve 5, a third pressure medium line 23 leads to the first connection 58 of pressure medium reservoir 9. In detail, simulator characterization valve 5 has a first line section 23a connected to the third pressure medium line 23, which serves as a main return line for the pressure medium. A second line section 23b branches off from the third pressure medium line 23 to the first connection 58 of the pressure medium reservoir 9 .

Furthermore, a third line section 23c leads from the third pressure medium line 23 to a return connection of the master brake cylinder 3. This is used to refill the pressure chamber 34 of the master brake cylinder 3 with hydraulic pressure medium. In addition, a throttle check valve device 28 is provided in the third pressure medium line 23 , the check valve of which opens in the direction of flow from the pressure medium reservoir 9 to the master brake cylinder 3 . Furthermore, the outlet valves 19a and 19b are connected to the third pressure medium line 23 via a fourth line section 23d in order to return pressure medium from the wheel brakes 8a and 8b to the pressure medium reservoir 9 .

Pressure modulation device 7 is connected to isolating valve 14 via a fourth pressure medium line 24 (brake supply line). Fourth pressure medium line 24 is divided by circuit valve 16 into a first line section 24a and a second line section 24b. Inlet valves 18a and 18b are connected to the first line section 24a. Inlet valves 18c and 18d are connected to the second line section 24b. In addition, the fourth pressure medium line 24 is connected to the sequence valve 17 via the second line section 24b. Second pressure sensor 56 is located on second line section 24b.

Pressure supply device 6 is connected to the sequence valve 17 via a fifth pressure medium line 25 . In detail, the fifth pressure medium line 25 is connected to an outlet of the pressure chamber 64 of the pressure supply device 6 . Inlet valves 18a-d of pressure modulator device 7 can be switched on by open switching valve 17 of pressure supply device 6, so that hydraulic pressure medium can be displaced in wheel brakes 8a-8d to build up brake pressure by actuating piston 64. When the circuit separating valve 16 is open, all four inlet valves 18a-18d of the wheel brakes 8a-8d are hydraulically connected to the pressure supply device 6, as a result of which a brake pressure is built up at the wheel brakes 8a-8d by means of the pressure supply device 6. When the circuit separating valve 16 is closed, only wheel brakes 8c and 8d of the rear axle HA are hydraulically connected to the pressure supply device 6 to build up brake pressure.

A sixth pressure medium line 26 (suction line) is provided for refilling the pressure chamber 64 of the pressure supply device 6 and leads from the second connection 59 of the pressure medium reservoir 9 to the pressure supply device 6 . This line is connected to a return connection from the pressure chamber 64 of the pressure supply device 6 . At this point there is also a spring-loaded check valve 27 which opens in the direction of the pressure supply device 6 . Hydraulic pressure medium can be sucked back in by moving the piston 63 back when the sequence valve 17 is closed. As a result, the pressure medium can flow from the pressure medium reservoir 9 into the pressure chamber 64 .

Conveniently, the second electro-hydraulic control and regulation unit 11 is arranged on a bulkhead of the motor vehicle. The first electro-hydraulic control and regulation unit 10 is not arranged on the bulkhead, but at another location in the engine compartment of the motor vehicle. First and second electrohydraulic control and regulation units 10 and 11 are then connected to one another via a first connecting line 51 and a second connecting line 52 . For this purpose, the first connection line 51 links a first line section 21a with a second line section 21b from the first pressure medium line 21. The first line section 21a is in the second electrohydraulic control and regulation unit 11 and the second line section 21b is in the first electrohydraulic control and regulation unit 10. In addition, the second connecting line 52 is linked third line section 23c with second line section 23b from third pressure medium line 23. The third line section 23c is in the second electrohydraulic control and regulation unit 11 and the second line section 23b is in the first electrohydraulic control and regulation unit 10.

If an actuation of brake pedal 2 is detected by travel sensor 53, isolating valve 14 is closed (energized) and simulator release valve (15) is opened (energized). This creates a pressure medium path from master brake cylinder 3 to simulation device 4 . The actuation of the master brake cylinder piston 32 shifts hydraulic pressure medium into the simulator pressure chamber 45 and acts there on the simulator piston 42 , which is supported on the simulator spring 43 . This simulates a brake feel on brake pedal 2. This means that when the brake pedal 2 is actuated, the vehicle operator is informed of a brake pressure build-up. Simulation device 4 follows a predetermined force-displacement characteristic. This is largely determined by the simulator spring 43. However, the actual brake pressure build-up is effected by pressure supply device 6. With the sequence valve 17 open, pressure supply device 6 transfers pressure medium via inlet valves 18a-18 from pressure modulator device 7 to wheel brakes 8a-8d.

However, because the characteristics of the simulation device 4 are predetermined and cannot be changed per se, this device cannot be used for different vehicle types in the sense of a modular system. Normally, a simulation device adapted to the vehicle type or the customer's requirements is always required 4.

In order to circumvent this problem, a simulator characterization valve 5 is provided as an example. Simulator characterization valve 5 is located parallel to simulator release valve 15 in a pressure medium path from simulation device 4 to pressure medium tank 9. While simulator release valve 15 is in a pressure medium path from pressure chamber 34 of master brake cylinder 3 to simulator pressure chamber 45 of simulation device 4, simulator characterization valve 5 is in a pressure medium path from simulator pressure chamber 45 of the simulation device 4 to the first connection 58 of pressure medium tank 9 is arranged. Simulator characterization valve 5 is preferably designed to be normally closed. It is controlled by the second electronic control and regulation unit 13 .

The provision of an additional pressure medium path from simulation device 4 to pressure medium tank 9 with the electrically switchable simulator characterization valve 5 located therein enables pressure medium to flow from simulator pressure chamber 45 into pressure medium tank 9 while brake pedal 2 is actuated and simulator release valve 15 is open. As a result of this measure, hydraulic pressure medium flows out of the simulator pressure chamber 45, as a result of which the characteristics of the simulation device 4 change.

In the 2 two force-displacement lines are shown schematically, which can be set with the exemplary simulator characterization valve.

The piston travel s of the master brake cylinder is plotted in millimeters [mm] on the x-axis. The foot force F in Newton [N] is plotted on the y-axis. A first characteristic curve is shown with K1 and a second characteristic curve with K2 for the characteristic of the simulation device. Characteristic curve K1 shows a curve with a closed simulator characterization valve and characteristic curve K2 shows a curve with a controlled simulator characterization valve that is fully open.

The force-displacement characteristic is usually divided into two sections. In a first section, the force-displacement characteristic is proportional and then increases progressively in a second section. The proportional section is created by a soft spring and the progressive section by a hard spring. This applies to both characteristic curves K1 and K2 shown. However, characteristic K2 is shifted to the right. This means that essentially the proportional section runs over a longer actuation path. I.e. the brake feel feels soft over a longer actuation path with characteristic K2. This other characteristic from the simulator is achieved by driving the simulator characterization valve 5 during a brake pedal application. By opening the simulator characterization valve, pressure medium escapes from the simulator pressure chamber, so that a lower force acts on the simulator piston. This makes the brake pedal feel softer.

A variable characteristic of the simulation device can be set in a range between the two characteristic curves K1 and K2 by proportional activation of the simulator characterization valve. This will thereby achieves that the opening cross-section of the simulator characterization valve is adjusted in a certain way. As a result, the volume flow of the hydraulic pressure medium from the simulator pressure chamber into the pressure medium reservoir can be regulated. This then leads to a different characteristic of the simulation device.

For example, when the brake pedal is actuated, the isolating valve is closed and the simulator release valve is opened. Actuation of the brake pedal shifts pressure medium into the simulation device. The second electronic control and regulation unit evaluates the signal from the travel sensor, which provides information about the driver's braking request or the travel distance of the master brake cylinder piston. At the same time, the second electronic control and regulation unit evaluates the signal from the first pressure sensor. The measured displacement signal and the measured pressure signal represent the actual force-displacement curve. This force-displacement curve is compared with a force-displacement characteristic stored in the second electronic control and regulation unit, which represents a desired characteristic of the simulation device. The second electronic control and regulation unit then controls the simulator characterization valve in such a way that the actual force-displacement curve follows the stored force-displacement characteristic. This is achieved by appropriately energizing the solenoid from the simulator characterization valve. Partially or also completely opening the simulator characterization valve reduces a pressure in the simulation device, which leads to a changed characteristic. The drained pressure medium then flows into the pressure medium reservoir.

This mode of operation makes it possible to represent different characteristics with a single simulation device. A normal, a sporty or a comfortable braking force characteristic can be set with one and the same simulation device. So it is not only possible to store a certain braking force characteristic for a vehicle type, but also different braking force characteristics can be stored in the electronic control and regulation unit for a vehicle type, which are then selected as required.

reference list

1

braking system

2

brake pedal

3

master cylinder

4

simulation facility

5

simulator characterization valve

6

print staging facility

7

pressure modulation device

8a-d

wheel brakes

9

pressure fluid reservoir

10

first electro-hydraulic control and regulation unit

11

second electro-hydraulic control and regulation unit

12

first electronic control and regulation unit

13

second electronic control and regulation unit

14

isolation valve

15

simulator release valve

16

circuit isolation valve

17

sequence valve

18a-d

intake valves

19a-d

exhaust valves

21

first pressure line

21a

first line section

21b

second line section

22

second pressure line

22a

first line section

22b

second line section

23

third pressure line

23a

first line section

23b

two line sections

23c

third line section

23d

fourth line section

24

fourth pressure medium line

24a

first line section

24b

second line section

25

fifth pressure line

26

sixth pressure medium line

27

check valve

28

Throttle check valve device

31

piston rod

32

master cylinder piston

33

return spring

34

pressure chamber

35

Housing

41

simulator housing

42

simulator piston

43

simulator spring

44

simulator rear chamber

45

simulator pressure chamber

46

piston space

47

first exit

48

second exit

49

Entry

51

first connection line

52

second connection line

53

displacement sensor

54

rotor position sensor

55

first pressure sensor

56

second pressure sensor

57

level sensor

58

first connection

59

second connection

61

electric motor

62

Rotation-translation gear

63

Pistons

64

pressure room

HA

rear axle

HL

back left

MR

back right

K1

first characteristic

K2

second characteristic

v.a

front axle

VL

front left

VR

front right

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• WO 2011029812 A1 [0002]
• DE 102014212536 A1 [0003]

Claims (9)

Brake system (1) for a motor vehicle, comprising: - a master brake cylinder (3) which can be actuated by a brake pedal (2), - a simulation device (4) which can be hydraulically connected to the master brake cylinder (3) by a simulator release valve (15), and - A pressure medium reservoir (9) under atmospheric pressure for storing a hydraulic pressure medium, characterized in that the pressure medium reservoir (9) can be switched on hydraulically by a simulator characterization valve (5) of the simulation device (4). Brake system (1) after claim 1 , characterized in that the simulation device (4) comprises a simulator pressure chamber (45) to which the pressure medium reservoir (9) is hydraulically connected when the simulator characterization valve (5) is open. Brake system (1) after claim 2 , characterized in that the master brake cylinder (3) is also hydraulically connected to the simulator pressure chamber (45) when the simulator release valve (15) is open. Brake system (1) according to one of Claims 1 until 3 , characterized in that the simulator characterization valve (5) is an analog switching valve. Brake system (1) according to one of Claims 1 until 3 , characterized in that the simulator characterization valve (5) is a proportional valve. Brake system (1) according to one of Claims 1 until 5 , characterized in that the simulation device (4) has a different characteristic curve when the simulator characterization valve (5) is open than when the simulator characterization valve (5) is closed. Method for operating a brake system (1) for a motor vehicle, the brake system (1) comprising the following: - a master brake cylinder (3) which can be actuated by a brake pedal (2), - a simulation device (4) which can be activated hydraulically by a simulator release valve (15) can be connected to the master brake cylinder (3), and - a pressure medium reservoir (9) under atmospheric pressure for storing a hydraulic pressure medium, characterized in that the pressure medium reservoir (9) is switched on hydraulically by a simulator characterization valve (5) of the simulation device (4). . procedure after claim 7 , characterized in that when the brake pedal (2) is actuated, a displacement signal and a pressure signal are evaluated to form a force-displacement curve and this force-displacement curve is compared with a predetermined force-displacement characteristic curve, and if a deviation is determined then the simulator characterization valve (5) is actuated. procedure after claim 7 or 8th , characterized in that the simulator characterization valve (5) is a proportional valve, wherein when the brake pedal (2) is actuated, a volume flow from the simulation device (4) to the pressure medium reservoir (9) is adjusted by the proportional valve.

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