JP2009513411A - Electrohydraulic brake system for automobile - Google Patents

Abstract

【Task】
To provide a brake device operating in a brake-by-wire mode in which the risk of leakage into the vehicle interior is reduced as much as possible.
[Solution]
The present invention relates to an automobile electrohydraulic brake device that can be operated in a brake-by-wire operation mode, and a master cylinder (1) to which a wheel brake cylinder can be connected, and a brake pedal (3). A first piston (2) connected to the second piston (4) for operating the master cylinder (1), a third piston (5) that can be operated by the first piston (2), The one piston (2) and the third piston (5) are provided with at least one brake pedal characteristic simulation device (6, 7) that exerts a simulation force, and the simulation device is comfortable for the driver by operating in the by-wire mode. All three pistons (2, 4, 5) as well as passage simulation device in one housing giving pedal sensitivity 8) a valve arranged in the valve and operable by the third piston (5) to reduce the pressure of the hydraulic pressure source (9) to a value that the hydraulic pressure source (9) and the second piston (4) can act on The second piston (4) and the third piston (5) are provided with the device (10), and the second piston (4) and the third piston (5) are moved by the intermediate chamber (11) by the pressure acting on the second piston (4) by the third piston (5). The present invention relates to an automobile electrohydraulic brake device that is separated from each other so as to act in a direction opposite to the acting direction of (4). According to this invention, the valve element (13) of the valve device (10) is embodied so that both front surfaces are subjected to the action of pressure governing the intermediate chamber (11).

Description

  The present invention relates to an electrohydraulic brake device for an automobile that can be operated in a brake-by-wire operation mode, and is connected to a master cylinder to which a wheel brake cylinder can be connected and a brake pedal. There is provided at least one brake pedal characteristic simulation device including a first piston, a second piston that operates a master cylinder, and a third piston that can be operated by the first piston, and the first piston and the third piston exert a simulation force. The simulation device is provided in a by-wire mode to give the driver a comfortable pedal sensitivity, all three pistons and the passage simulation device are arranged in one housing, the hydraulic pressure source and the second piston The pressure of the hydraulic pressure source to the value that can act A valve device that can be actuated by a third piston in order to reduce the second piston and the third piston in a direction opposite to the direction of action of the second piston by the pressure exerted by the third piston on the second piston by the intermediate chamber The present invention relates to an automobile electrohydraulic brake device that is separated from each other.

  In automotive technology, brake-by-wire brake systems always find great popularity. In this brake system, the brakes are independently activated based on electronic signals without the driver's active assistance. This electronic signal can be output, for example, from an electronic stability program ESP or an interval adjustment (collision avoidance) system ACC. When driver actuation imposes this kind of independent actuation, the car driver will feel the brake pedal reaction. Because this reaction effect on the brake pedal is unusual or unpleasant for the driver, the driver does not operate the brake pedal as strongly as needed in this situation in road traffic critical situations. This is because the driver is confused by the reaction to the brake pedal caused by the brake operation.

EP-A-10788331 (Patent Document 1) describes an electrohydraulic brake device of the aforementioned kind. The valve device for reducing the pressure of the pressure source is formed as a slider valve that can be mechanically operated by a tilt lever in the case of a brake device known in advance, and the slider valve is movably guided in a hole provided in the housing. Yes. Since a hole to the atmosphere is formed to attach the slider and the pressure spring that biases the slider, there is a risk of leakage in this region that may be due to contamination of the vehicle interior.
European Patent Application No. 10788331

  The object of the present invention is therefore to provide a brake device of the kind described in which the risk of leakage into the vehicle interior is reduced as much as possible. In addition, the brake device has a simple configuration and can be manufactured at low cost.

  According to the present invention, this problem is solved by the fact that both front surfaces of the valve body of the valve device are subjected to the action of the pressure governing the intermediate chamber.

  Preferred embodiments of the invention are given in the dependent claims 2 to 36.

  Next, for example, embodiments of the present invention will be described in detail with reference to the accompanying schematic drawings. FIG. 1 shows the configuration of the braking device of the invention according to the first embodiment in a stationary state, and FIG. 2 shows the braking of the invention according to FIG. 1 during the pressure-holding phase of independent braking that is guided independently of the driver demand. FIG. 3 shows the brake system of the present invention according to FIG. 1 during the preferred “brake-by-wire braking” pressure holding phase, FIG. 4 shows the so-called hydraulic descent during loss of the electric current supply or FIG. FIG. 5 shows the brake device of the invention according to FIG. 1 in mode, FIG. 5 shows the brake device of the invention according to FIG. 1 in the loss of a pressure source or in so-called mechanical lowering mode, and FIG. FIG. 7 shows the configuration of the second embodiment of the invention, FIG. 7 shows the second embodiment of the brake device in a stationary state, and FIG. 8 shows this embodiment of the brake device in a stationary state. It shows the configuration of a fourth embodiment of the.

  FIG. 1 shows the brake device of the present invention in a stationary state. The brake device is fixedly connected to the first piston 2 via the operating rod 36. The brake pedal path can be detected by a path sensor 17. The first piston 2 is arranged in the third piston 5, and at this time, the hydraulic chamber 21 is arranged between the first and third pistons 5, and elastic elements 6, 7 forming a brake pedal characteristic simulation device. As a result, a connection occurs between the first piston 2 and the third piston 5.

  Further, a second piston 4 attached to the master cylinder 1 and capable of generating pressure is provided in the cylinder. The master cylinder 1 is connected to an unillustrated wheel brake of the vehicle via an electrohydraulic adjustment or control unit, schematically shown in the anti-lock system (ABS).

  The first piston 2, the second piston 4 and the third piston 5 are accommodated in one housing 8. There is an intermediate chamber 11 between the third piston 5 and the second piston 4 that is filled with a pressure medium. The control of the pressure in the intermediate chamber 11 takes place in a brake-by-wire operating mode (see FIG. 3) which is preferred for the following type: the driver moves the first piston 2 into the elastic element when the brake pedal 3 is activated. Move against the spring force of 6 and 7. The elastic elements 6 and 7 are formed so that a brake sensitivity corresponding to a usual brake pedal can be transmitted to the driver. This means that the resistance slowly increases with a small brake pedal path and increases disproportionately with a large brake pedal path. By actuating the brake pedal 3, the third piston 5 can also be moved in the direction of the second piston 4, so that the first valve device 10 is already activated after a very slight transition. The first valve device 10 is formed as a hydromechanical reinforcing valve in the illustrated example, and the valve has a valve body 13 biased in the direction toward the second piston 4 by a spring, and the role thereof is as follows. The second control edge described in the text. As shown in the drawing, the hydraulic coupling part 12 formed in the valve body 3 by the axial through-holes not shown in the drawing or formed alternately in the housing 8 is opposite to the intermediate chamber 11 of the valve body 13. It is possible to apply a regulated pressure in the intermediate chamber 11 to the front face. At this time, the valve body 13 cooperates with one actuating element formed as a radial protrusion 14 formed on the third piston 5 in the illustrated embodiment. If the third piston 5 moves slightly in the direction of the second piston 4, the valve body 13 moves very long until a connection between the intermediate chamber 11 and the hydraulic pressure source 9 is formed. This connecting portion is formed by a hydraulic pressure conduit 23 whose right control side in the drawing of the valve body 13 guides from the pressure source 9 or a conduit portion 33 branched from the pressure source 9 and a pressure medium passage 34 communicating with the intermediate chamber 11. Formed by opening a flow passage between. The hydraulic pressure source 9 is preferably formed by a high-pressure accumulator 19 loaded by a motor pump assembly 20. The motor pump assembly 20 comprises an electric motor 26 and a hydraulic pump 27, the suction side of which is connected to a pressure medium storage container 22 without pressure, while the pressure side of the pump is connected via the conduit 23. A high-pressure accumulator 19 is connected. In the conduit 23, a check valve 24 that opens to the high-pressure accumulator 19 is attached, and at this time, the pressure sensor 39 enables monitoring of the load state of the high-pressure accumulator 19. The high-pressure accumulator 19 assists the pump 27 especially when, for example, during rapid full braking, the pump 27 must be able to create a pressure that can be readily prepared based on its mass inertia in a short time. The intermediate chamber is pressurized by the connection between the high-pressure accumulator 19 and the intermediate chamber 11, whereby the second piston 4 generates pressure in the master cylinder 1 and the third piston 5 stops in the housing 8. Pressed in the direction of 35, the third piston hits the stopper before the brake is actuated. The second valve device 51 comprises a valve 15 connected to the high-pressure accumulator 19, a pressure generating valve connected in a non-energized state, and a valve 16 mounted in the pressure medium passage 34. In the illustrated embodiment, Since the separation valve 16 is opened without energizing energy, the pump 27 or the high-pressure accumulator 19 can be acted on via the coupling portion. The pressure sensor 18 can detect the pressure adjusted in the intermediate chamber 11. The energy energization of the separation valve 16 can be prevented from flowing out of the pressure medium from the intermediate chamber 11 by the valve device 10, while the pressure medium can be supplied to the intermediate chamber 11 by the energy energization of the pressure generating valve 15.

  In the non-operating state of the brake pedal 3 (see FIG. 1), the first piston 2 is pressed against the stopper 37 formed in the third piston 5 via the elastic elements 6 and 7.

  In the first operation mode in which the pressure holding phase is illustrated in FIG. 2 and is characterized by the braking process regardless of the driver's request, the operating pressure in the intermediate chamber 11 is newly calculated continuously by the control of the second valve device 52. It is adapted to the target pressure value. For this reason, the volumetric flow to the valve device 10 can be prevented by energizing the separation valve 16, and a reverse volumetric flow from the first valve device 10 through the separation valve 16 to the pressure generation in the intermediate chamber 11 is possible. Sex remains preserved. The higher operating pressure, which is electronically controlled by the pressure generating valve 15 and provides a hydraulic mechanical reinforcement valve to the valve device 10, is adjusted. Due to the electronically controlled pressure drop, the energization of the isolation valve 16 takes place temporarily, so that the pressure medium is in this mode of operation to the first valve device 10 which creates a connection to the pressure medium storage vessel 22. Can be released. This joint is formed by opening the flow passage between the pressure medium passage 34 and the hydraulic joint 38 that guides from the first valve device 10 to the pressure medium storage container 22 at the left control side of the valve body 13 in the drawing. Has been. This electronic brake pressure adjustment has the advantage that its transmission behavior can be freely selected within the dynamics given by the technical data of the high pressure accumulator, pressure generating valve and isolation valve. Therefore, the so-called jump function, that is, jump to a predetermined brake pressure value when contacting the brake pedal 3, brake auxiliary function, for example ASR (drive slip control), ESP (electronic stability program) and ACC (adaptive action control) Automatic brake actuation as required for is realized by software measures. For this purpose, the driver reference value in the form of brake pedal actuation, detected by a transition sensor, a power sensor or other type of sensor, is converted into wheel brake pressure from a calculation unit (not shown) by using an appropriate algorithm. This wheel brake pressure is realized in an independent power brake module and the next ABS hydraulic unit by an electronically controllable valve.

  In the second brake-by-wire operation mode, the pressure holding phase is illustrated in FIG. 3 and is characterized by an independent braking process guided by the driver's delay request. Is adjusted by appropriate control of the valves 15, 16 in response to a signal from the transition sensor 17 which detects the desire. In the pressure holding phase illustrated in FIG. 3, the pressure generating valve 15 remains unenergized while the isolation valve 16 is energized and held in its closed position. Furthermore, the brake-by-wire mode of operation in electrohydraulic brake devices is known and therefore need not be discussed in detail.

  In a third operating mode characterized by a loss of current supply or a so-called hydraulic drop mode (see FIG. 4), the solenoid valves 15 and 16 remain energized. As a result, the valve device 10, that is, the hydraulic mechanical reinforcing valve controls the operating pressure in the intermediate chamber 11 and reinforces the braking force. At that time, the pressure generation is controlled by the cooperation of the right control side in the drawing of the conduit portion 33 and the valve body 13. As long as the high-pressure accumulator 19 can be supplied with a pressure medium under pressure, the hydraulic reinforcement operates without electricity. There is a linear power reinforcement whose reinforcement factor is always given in advance by the ratio of the cross-section from the second piston 4 to the third piston 5.

  In a fourth operating mode characterized by a lack of hydraulic pressure in the pressure accumulator 19 or a so-called mechanical lowering mode (see FIG. 5), the brake device can be operated purely mechanically and the third piston 5 is guided by the brake pedal 3. Therefore, the operation of the master cylinder 1 is performed exclusively by muscle force. Since the communication of the conduit 50 connected to the hydraulic chamber 21 passes through the fixed packing 41 arranged in the housing 8, the hydraulic chamber 21 is closed by the relative movement of the third piston 5 with respect to the housing 8. Since the functions of the brake pedal characteristic simulation devices 6 and 7 are blocked by the closing, direct power transmission from the first piston 2 to the third piston 5 occurs.

  FIG. 6 shows a second embodiment according to the present invention, wherein the hydraulic chamber 21 is partially limited to the third piston 5 and partially to the second piston 4 by the first piston 2. A hydraulic joint between a portion 42 formed in the third piston 5 of the chamber 21 and a portion 43 formed in the second piston 4 is a hole 44 formed perpendicular to each other in the first piston 2. 45. At this time, the elastic element 6 or the compression spring 46 of the brake pedal characteristic simulation device is arranged outside the hydraulic chamber 21 (or 42) and remains dry. The second compression spring 47 that supports the action of the compression spring 46 supports the second piston 4 on the other hand on the first piston 2. The third compression spring 48 urges the third piston 5 against the operating direction of the brake device, and is supported by the installation surface 49 disposed in the housing 8.

  In the case of the third embodiment of the brake device according to the invention shown in FIG. 7, the valve device 10 is actuated by a lever or cross bar 31 which cooperates with the third piston 5. The horizontal bar 31 connected in power transmission with the valve body 13 is supported in the housing 8 and through a recess 53 formed in the third piston 5 in a stationary state, particularly with respect to the longitudinal axis of the third piston 5. It extends vertically and is supported by the type of two-armed lever in the protrusion 54 formed on the third piston 5 under the action of the spring 32.

  In the case of the third embodiment shown in FIG. 8 of the brake device according to the present invention, the motor pump assembly 20 is integrated with the electrohydraulic control adjustment unit 28. The suction side of the pump 27 is arranged between the housing 8 and the control or adjustment unit 28 and is supplied with pressure medium under atmospheric pressure via a first hydraulic coupling 50 leading to the pressure medium storage container 22. The pressure medium applied under high pressure from the pump 26 extends to the inside of the second hydraulic coupling portion 51 disposed between the control or adjustment unit 28 and the housing 8 and the housing 8 and is supplied to the pressure accumulator 19 through the coupling portion 52. Is done. At this time, a valve 25 that can be electrically connected, in particular, a 2/2 passage valve, is attached to the coupling portion 52, and the valve fulfills the function of a check valve that opens to the high-pressure accumulator 19 in the first connection state. In the connected state, the hydraulic coupling portion 51 is opened. In the open coupling 51, the control or regulating unit can be supplied with hydraulic energy from the high pressure accumulator 19 when the motor pump assembly 20 is inactive or not yet ready for operation. Given this feature, the electrically connectable valve 25 can be replaced with a check valve.

Further, the electrohydraulic control adjustment unit 28 includes a device 30 that returns the excess pressure medium volume generated in the antilock control operation to the master cylinder 1. The feedback device 30 which can be driven by the pressure transmitted from the motor pump assembly 20 and by the pressure present in the high-pressure accumulator 19 is formed by at least two low-pressure accumulators 30a, 30b, 40a, 40b, these low-pressure accumulators descending alternately. The pressure medium volume that receives or descends the pressure medium volume is pressed against the master cylinder 1 in the feedback direction by the action of the driving pressure. In the illustrated embodiment, two groups of low pressure accumulators 30a, 30b and 40a, 40b are provided, with each brake circuit I, II having a pair of low pressure accumulators 30a, 30b; Each of I and II is attached so that a low-pressure accumulator attached to one group a and group b can be substituted. The low pressure accumulators 30a, 30b and 40a, 40b are acted on the pressure transmitted from the motor pump assembly 20 on the side facing away from the low pressure connection portion, so that the brake circuit side pressure medium contained therein The volume can be returned to the master cylinder 1. At this time, both groups 30a, 30b and 40a, 40b operate periodically based on the theme:
-Return of the first group 30a, 40a,
・ Do not return,
-Return of the second group 30b, 40b,
・ Do not return.

  Pressure action is effected by means of a valve arrangement 29 attached to the motor pump assembly 20, at least one low pressure accumulator per brake circuit is included in the electrohydraulic control adjustment unit 28 at each point in time, not shown in detail. The pressure medium is controlled so as to accommodate the released pressure medium. In that case, the valve arrangement 29 consists in particular of four valves 53, 54, 55 and 56, which are in the form of an H-bridge connection, with the valve pair 53, 54 being connected to the first low-pressure reservoir group 30a, 40a, The valve pairs 55 and 56 are connected so as to be attached to the second low-pressure accumulator groups 30b and 40b. Switching the valves 53 and 55 causes the low-pressure accumulator group to act independently, while switching the valves 54 and 56 causes the low-pressure accumulator group to be connected to the pressure medium storage container 22, that is, atmospheric pressure by the hydraulic coupling 50. Yes.

  The control of all the valves and the electric motor 26 uses an electronic control unit (not shown) which forms a control or adjustment unit 28 and a component unit, and the control unit uses the sensors 17, 18 and 39 as input information. Provided with output signal.

The structure of the brake device of this invention by the 1st embodiment in a stationary state is shown. Fig. 2 shows the braking device of the present invention according to Fig. 1 during the pressure-holding phase of independent brake operation guided independently of the driver request. Fig. 2 shows the brake system of the present invention according to Fig. 1 during a preferred "brake-by-wire braking" pressure hold phase. 1 shows the brake device of the invention according to FIG. 1 during the loss of an electric current supply or in the so-called hydraulic lowering mode. FIG. 2 shows the braking device of the invention according to FIG. 1 during the loss of the pressure source or in the so-called mechanical lowering mode. The structure of the 2nd embodiment of this invention of the brake device in a stationary state is shown. 2 shows a second embodiment of the invention of the brake device in a stationary state. The structure of the 4th embodiment of this invention of the brake device in a stationary state is shown.

Explanation of symbols

1. . . . . Master cylinder . . . . First piston . . . . Brake pedal . . . . Second piston 5. . . . . Third piston 6. . . . . Elastic element 7. . . . . Elastic element 8. . . . . Housing 9. . . . . Hydraulic sensor 10. . . . Valve device 11. . . . Intermediate room 12. . . . Hydraulic coupling part 13. . . . Valve body 14. . . . Radial protrusion
15. . . . Solenoid valve 16. . . . Solenoid valve 17. . . . Transition sensor 18. . . . Pressure sensor 19. . . . High pressure accumulator 20. . . . Motor pump assembly 21. . . . Hydraulic chamber 22. . . . Pressure medium storage container 23. . . . Conduit 26. . . . Pump 28. . . . Electrohydraulic control adjustment unit 29. . . . Valve arrangement equipment 30. . . . Low pressure accumulator 40. . . . Low pressure accumulator 46, 47, 48. . . . Compression spring 52-56. . . . valve

Claims (36)

  An electrohydraulic brake device for an automobile that can be operated in a brake-by-wire operation mode, which is connected to a master cylinder (1) to which a wheel brake cylinder can be connected, and a brake pedal (3). A first piston (2), a second piston (4) that operates the master cylinder (1), a third piston (5) that can be operated by the first piston (2), and a first piston (2 ) And the third piston (5) are provided with at least one brake pedal characteristic simulation device (6, 7) which exerts a simulation force, which gives the driver a comfortable pedal sensitivity in the by-wire operating mode. All three pistons (2, 4, 5) and the passage simulation device are arranged in one housing (8). A hydraulic pressure source (9) and a valve device (10) operable by the third piston (5) to reduce the pressure of the hydraulic pressure source (9) to a value that the second piston (4) can act on. The second piston (4) and the third piston (5) are operated by the second piston (4) by the pressure applied by the third piston (5) to the second piston (4) by the intermediate chamber (11). In the electrohydraulic brake device for automobiles separated from each other so as to act in the direction opposite to the direction, both front surfaces of the valve body (13) of the valve device (10) have a pressure governing the intermediate chamber (11). An electrohydraulic brake device for an automobile characterized by being acted upon.   The one front surface of the valve body (13) is subjected to the action of pressure governing the intermediate chamber (11) via a hydraulic coupling part (12) provided in the housing (8). Brake device according to claim 1.   The brake device according to claim 1, wherein both front surfaces of the valve body (13) are communicated with each other in the valve body (13) through a long hole.   4. Direction of movement of the valve body (13) and the third piston (5) is equal when the valve device (10) is actuated by the third piston (5). Brake device according to claim 1.   5. A brake device according to claim 1, wherein the valve body (13) can be actuated directly by the third piston (5).   The third piston (5) is provided with a radial protrusion (14) cooperating in power transmission with the front face of the valve body (13) facing the intermediate chamber (11). The brake device described.   The valve body (13) cooperates with the third piston (5) and is supported in the housing (8) and is arranged in particular perpendicular to the longitudinal axis of the third piston (5) by means of a lever or a horizontal bar (31). The brake device according to any one of claims 1 to 4, wherein the brake device is operable.   8. The brake device according to claim 1, wherein the hydraulic pressure source (9) is formed by a high-pressure accumulator (19) that can be loaded by a motor pump assembly (20).   A second valve device (15, 16) that can be electrically operated by an electronic control unit is provided, and the pressure supplied into the intermediate chamber (11) can be influenced by the second valve device, and these second valve devices The brake device according to any one of claims 1 to 7, characterized in that is integrated in the housing (8).   The pressure sensor (39) is provided for monitoring the load condition of the high pressure accumulator (19), the output signal of which is supplied to the electronic control unit, and the control unit is integrated in the housing (8), Alternatively, the brake device according to any one of claims 1 to 9, wherein the brake device is integrally connected to the housing.   The pressure sensor (18) is provided for detecting the pressure that dominates in the intermediate chamber (11), the output signal of which is supplied to the electronic control unit, and the control unit is integrated in the housing (8). The brake device according to any one of claims 1 to 10, wherein the brake device is integrally connected to the housing.   The high pressure accumulator (19) is directly disposed in the housing (8), and the hydraulic connection (23) between the pressure surface of the pump (27) of the motor pump assembly (20) and the high pressure accumulator (19). The brake device according to any one of claims 8 to 11, characterized in that is formed by at least one hole provided in the housing (8).   13. The brake device according to claim 12, wherein a check valve (24) that opens to the high-pressure accumulator (19) is attached to the hydraulic connection part (23).   14. The brake device according to claim 1, wherein an electrohydraulic control or adjustment unit (28) of an anti-lock system (ABS) is connected to the master cylinder (1).   15. The electrohydraulic control or adjustment unit (28) is operated according to the reverse feed principle and comprises a device (30) for reverse feed from the excess pressure medium volume to the master cylinder (1). Brake device.   14. The brake device according to claim 1, wherein the motor pump assembly (20) is integrated in an electrohydraulic control or adjustment unit (28).   The pump (27) is supplied with a pressure medium under atmospheric pressure via a first hydraulic connection (50) arranged between the housing (8) and the control or adjustment unit (28), and the pump (27) The pressure medium delivered under pressure extends into the housing (8) of the hydraulic connection (23) via a second hydraulic connection (50) arranged between the control or adjustment unit (28) and the housing (8). 17. Brake device according to claim 16, characterized in that it is fed to a part (52) for guiding to a high-pressure accumulator (19).   18. Brake device according to claim 17, characterized in that a check valve (24) which opens to the high-pressure accumulator (19) is mounted in the part (52).   A valve (25), in particular a 2/2 passage valve, is mounted in the part (52), which can be electrically connected, fulfilling the function of a check valve that opens to the high-pressure accumulator (19) in the first switching position, 18. The brake device according to claim 17, wherein the hydraulic connecting part (51) is opened at the second switching position.   16. Brake device according to claim 15, characterized in that the device (30) for feeding back the excess pressure medium volume can be driven by the pressure generated by the motor pump assembly (9).   16. Brake according to claim 15, characterized in that the device (30) for feeding back the excess pressure medium volume can be driven by the pressure generated from the motor pump assembly (9) as well as by the pressure present in the high-pressure accumulator (19). apparatus.   The device (30) is formed by at least two low-pressure accumulators (30a, b; 40a, b), which receive alternating pressure medium volumes or reverse feed by the action of the pressure driven by the resulting pressure medium volume. The brake device according to claim 20 or 21, wherein the brake device is excluded in a direction.   The motor pump assembly (20) or the high-pressure accumulator (19) is connected to the electrically connectable valve (25) and cooperates with the valve arrangement body (29), and the valve arrangement body carries out alternately driven pressure or atmospheric pressure. The brake device according to any one of claims 20 to 22, wherein the brake device is provided in a low-pressure accumulator (30a, b; 40a, b).   24. Brake device according to claim 23, characterized in that the valve arrangement (29) is integrated in an electrohydraulic control or adjustment unit (28).   The brake pedal characteristic simulation device comprises at least one elastic element (6, 7), which elastic element damping force depends on the relative speed between the first piston (2) and the third piston (5). The brake device according to any one of claims 1 to 24, wherein a component is exerted.   The brake pedal characteristic simulation device includes at least one damping device, which damping device exerts a damping force component of the simulator force depending on the relative speed between the first piston (2) and the third piston (5). 26. A brake device according to claim 25, characterized in that:   27. Brake device according to claim 25 or 26, characterized in that the brake pedal characteristic simulation device (6, 7) comprises at least one component exerting a simulator force, "steel spring, elastomer body and friction joint".   The brake pedal characteristic simulation device (6, 7) is capable of being stopped so as to prevent movement of the first piston (2) relative to the third piston (5) in the direction of operation that exits beyond the current piston position. The brake device according to any one of claims 25 to 27, wherein the brake device is characterized in that   29. Brake device according to claim 28, characterized in that the brake pedal characteristic simulation device (6, 7) is stopped depending on the relative path of the third piston (5) with respect to the housing (8).   The brake pedal characteristic simulation device cooperates with a hydraulic chamber (21) defined in the third piston (5) by the first piston (2), and the hydraulic chamber is pressurized via another hydraulic coupling (50). 30. Brake device according to claim 29, characterized in that it is connected to the pressure medium storage container (22) and can be closed by relative movement of the third piston (5) with respect to the housing (8).   The brake pedal characteristic simulation device is characterized in that it can be stopped to prevent movement of the first piston (2) relative to the second piston (4) in the direction of operation in which it exits beyond the current piston position. The brake device according to any one of 25 to 27.   The brake pedal characteristic simulation device cooperates with the hydraulic chambers (42, 43, 44, 45) defined by the first piston (2) in the third piston (5) and in the second piston (4). 30. Brake device according to claim 29, characterized in that the chamber is connected to a pressureless pressure medium storage container (22) and can be closed by relative movement of the third piston (5) with respect to the housing (8).   The damping of the brake pedal characteristic simulation device (6, 7) or at least part of the damping is achieved by the hydraulic coupling (50) between the hydraulic chamber (42, 43, 44, 45) and the pressureless pressure medium storage container (22). The brake device according to any one of claims 30 to 32, wherein the brake device is achieved by appropriate dimension measurement.   Braking device according to claim 33, characterized in that the damping of the brake pedal characteristic simulation device (6, 7) is achieved by a damping device mounted in the hydraulic coupling (50).   The brake device according to claim 34, wherein the damping device comprises a hydraulic orifice and has a damping characteristic that depends on a return direction.   36. Brake device according to any one of claims 27 to 35, wherein the components exerting the simulator force are respectively arranged outside (dry) or inside (wet) of the hydraulic chamber (21).

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