EP2704930A1

EP2704930A1 - Pedal travel simulator, actuating unit for a hydraulic brake system and brake system

Info

Publication number: EP2704930A1
Application number: EP12715076.1A
Authority: EP
Inventors: Alfred Eckert; Ronald Bayer; Johann Jungbecker; Stefan A. Drumm; Johannes GÖRLACH; Marco Besier; Lothar Schiel
Original assignee: Continental Teves AG and Co OHG
Current assignee: Continental Teves AG and Co OHG
Priority date: 2011-05-02
Filing date: 2012-04-11
Publication date: 2014-03-12
Also published as: CN103502066A; US20140144732A1; KR20140030227A; DE102012203099A1; WO2012150108A1

Abstract

The invention relates to a pedal travel simulator (4, 104) for the hydraulic connection to a pressure chamber (8) of a master brake cylinder (3) of a hydraulic brake system, in particular for motor vehicles, comprising a housing (5, 30, 105) and a simulator piston (18, 118) that is displaceably mounted in the housing, wherein the simulator piston delimits a first hydraulic simulator chamber (16, 116) together with the housing, which simulator chamber can accommodate pressurizing media, wherein an elastic restoring means (19, 119) acts on the simulator piston (18, 118), wherein the pedal travel simulator (4, 104) comprises a second hydraulic simulator chamber (26, 126) for accommodating pressurizing media, said simulator chamber being delimited by an elastically deformable membrane (32, 132). The invention further relates to an actuating unit for a hydraulic motor vehicle brake system of the "brake-by-wire" type and to a hydraulic motor vehicle brake system.

Description

Pedal travel simulator, operating unit for a hydraulic brake system and brake system

The invention relates to a pedal travel simulator according to the preamble of claim 1 and an actuating unit for a hydraulic automotive vehicle brake system and a hydraulic motor vehicle brake system with such Pe ^¬ dalwegsimulator.

There are known hydraulic vehicle brake systems, which are designed as power-brake systems and in addition to a muscle-operated master cylinder, are hydraulically connected to the wheel brakes and the pressure and volume for actuating wheel brakes, a further, electrically controllable pressure and Volumenbereitstel ^¬ lunge means include in a "Brake-by-wire" - operating mode which activates the wheel brakes Only in case of failure of the electrically controllable pressure and volume supply device is the brake system actuated by the muscular force of the driver (fallback mode). which gives the driver in the brake-by-wire mode a familiar brake pedal feel.

From WO 2011/029812 Al an electro-hydraulic brake system with a muscle-operated master cylinder is known, at the first pressure chamber, a hydraulic pedal travel simulator can be connected. The pedal travel simulator includes a simulator piston having a

Simulator chamber separates from a simulator spring chamber. The simulator chamber is hydraulically connectable to the first pressure chamber of the master cylinder. In the

Simulator spring chamber is arranged a simulator spring on which the simulator piston is supported. A disadvantage of the brake system is felt that the force-displacement characteristic generated during a driver operation due to frictional forces, stick-slip effects and / or biasing forces of the individual elements of the master cylinder and pedal travel simulator one or more discontinuities, i.

Force jumps, may have. These occur in particular at low pedal forces, ie in an area in which discontinuities in the pedal feel by the driver are perceived as particularly disturbing or unpleasant.

The present invention therefore has for its object to provide a pedal travel simulator, an actuating unit for a hydraulic automotive vehicle brake system or a hyd ^¬ raulische automotive vehicle brake system with such betae ^¬ actuating unit, which is / are the driver, low especially in pedal travel or pedal forces, a improved, in particular perceived as a continuous, force-displacement characteristic. The pedal travel simulator or the actuating unit is intended to give the driver a pleasant brake pedal feeling and in particular especially when "breaking free" of the simulator piston no

Force jump show, which is noticeable as an unwanted jerk on the brake pedal. Furthermore, the Pedalwegsimula ^¬ gate should be designed structurally simple and inexpensive to produce.

This object is achieved by a Pedalwegsi ^¬ mulator according to claim 1, an operating unit according to ^¬ claim 13 and a brake system according to claim 15.

The invention is based on the idea that the pedal travel simulator ^¬ comprises a second hydraulic simulator chamber for receiving pressure medium, which is bounded by an elas ^¬ shows deformable membrane. The second

Simulatorraum represents an additional, jerk-responsive ^¬ de pressure medium volume uptake, by which any leaps in the first limited by the simulator piston acted upon by the Rückstellmit ^¬ tel

Simulator space conditional force-displacement characteristic are sorted out.

Preferably, the first and the second simulator chamber being connected hyd ^¬ raulisch parallel so that the major portion of the force-displacement characteristic of the pedal travel simulator is contributed by the limited of the acted upon by the return means simulator piston first simulator chamber, which simply by appropriate design of the return ^¬ means is possible, and by the responsive Volu ^¬ men aufnehmdenden second simulator space, which may be designed to be correspondingly smaller, the pedal feel is optimized.

A deformation of the membrane is preferably spatially by at least one boundary contour of a membrane support body limited. To achieve a compact design of the membrane support body is formed in the simulator piston.

It is preferred that the maximum receiving volume of the second simulator space is defined by the boundary contour of the membrane support body or the simulator piston. In this way, the effect of the second simulator space as pressure medium receiving volume can be reduced to the range of small pressures, i. a response range of the force-displacement characteristic are limited.

The membrane support body (or the simulator piston) and the membrane advantageously limit a receiving space, which is reduced by the expansion / deformation of the membrane depending on the pressure until the membrane comes to rest against the boundary contour of the membrane support body. Advantageously, the receiving space is connected to atmospheric pressure. For this purpose, the receiving space itself may be directly connected to atmospheric pressure and / or via at least one connecting line with a space, e.g. the space in which the return means is arranged to be connected, which is connected to atmospheric pressure.

According to one embodiment of the invention, the elastic return means is arranged in a space which is bounded by the simulator piston and the housing and which is sealed off from the first simulator space, wherein this space is also connected to atmospheric pressure. For this purpose, the space itself may be directly connected to atmospheric pressure and / or be connected via at least one connecting line with the receiving space, which is connected to atmospheric pressure. Because the pedal-side surface of the master cylinder is also pressurized with atmospheric pressure. is so ensured that the function of the actuator is independent of the value of the prevailing atm ^¬ atmospheric pressure.

For a uniform force-displacement characteristic, the first and the second simulator space are preferably hydraulically connected to one another via at least one connecting line.

According to a preferred disclosed embodiment, the pedal travel simulator according to the invention comprises ge these two spatially separated ^¬ units, the first unit the first

Simulator space and the simulator piston and the second unit comprises the second simulator space and the elastically deformable membrane. For a compact construction, the two units are particularly preferably arranged in a common housing ^¬ Ge.

The two units are preferably connected in parallel hydraulically, in order to achieve the smoothing of force jumps when receiving pressure medium in the first simulator space.

Advantageously, the second unit comprises a hollow ^¬ space, in which the diaphragm and a diaphragm supporting body arranged at a boundary contour for the membrane, wherein the membrane separates the second simulator chamber by a receiving space which is arranged between the diaphragm support body and the membrane.

According to another preferred embodiment of the pedal travel simulator according to the invention, the second one is

Simulator space arranged in a cavity of the simulator piston. This allows the pedal travel simulator to be executed in a single unit. This is the second one Simulator space particularly preferably arranged in a restoring ^¬ medium opposite region of the simulator piston, whereby the arrangement of connecting channels between rooms simplifies and the space requirement is reduced.

The second simulator space is preferably bounded by the diaphragm arranged in the simulator piston and a piston end cover of the simulator piston. By a piston cap ^¬ the production of the pedal travel simulator is simplified. The assembly of the membrane and the Kolbenstirnde ^¬ cekel in the simulator piston is particularly preferably by pressing into the simulator piston.

The aforementioned hydraulic connection between the simulator spaces is preferably realized here by means of a connecting channel arranged in the piston end cover.

At the piston end cover a ^{Begrenzungskon ¬ structure} is preferably formed, on which the membrane in a

unactuated state of the pedal travel simulator is substantially present. The shaping of the limiting contour can influence the force-travel characteristic of the pedal travel simulator.

According to one embodiment of the invention is in the cavity of the simulator piston, a receiving space which is bounded by the membrane and a simulator piston formed in the boundary contour. The membrane can thus deform by the receiving space is reduced and the second simulator space is increased until the maximum recording volume of the second simulator space is reached when the Memb ^¬ ran to the limiting contour. In the simulator piston, at least one further connecting channel is preferably arranged, via which the receiving space is connected to a space accommodating the elastic return means in order to ensure a pressure equalization between receiving space and return means receiving space and the necessary connection for the function to the atmospheric pressure.

The invention also relates to an actuating unit for ei ^¬ ne hydraulic motor vehicle brake system of the type "brake-by-wire" with an actuated by means of a brake pedal master cylinder with at least one pressure chamber to the wheel brakes are hydraulically connected, and

a pedal travel simulator according to the invention and a hydraulic motor vehicle brake system with such a Betä ^¬ tigungseinheit.

According to a development of the operating unit or of the motor vehicle brake system is in the hydraulic Verbin ^¬ connection between the, for example, first, the pressure chamber of the master cylinder and the pedal travel simulator is provided a switching device, which of the "brake-by-wire" mode by their activation of the pressure chamber Master cylinder locks the first and second simulator room and outside the "brake-by-wire" mode by terminating the Akti ^¬ vation disconnected.

In order to enable an undamped release of the brake pedal in the "brake-by-wire" mode and emptying the simulator rooms in the unactuated state of the brake pedal, the switching device is preferably connected by an electrically controllable sequence valve and the Zuschaltventil pa ^¬ rallel switched, in the direction of the master cylinder opening check valve formed. The power is removed ^¬ sen fallback, the pedal travel is thus invalid, the connecting valve is advantageously performed normally closed.

An advantage of the invention is an inexpensive improvement of the brake pedal characteristics of an actuating unit for a hydraulic automotive vehicle brake system ^¬. The force-travel characteristic of known actuators, which is often criticized by drivers for small pedal travel as unsteady, is harmonized.

Further advantageous developments of the invention can be taken from the subclaims.

Other features, advantages and preferred embodiments of the invention will become apparent from the following description with reference to FIGS.

It show schematically

Fig. 1 shows an embodiment of an inventive

Actuator with a first embodiment ^¬ example of a Pedalwegsimula ^¬ sector invention,

2 a part of the pedal travel simulator of the first ^exemplary embodiment in exploded view,

3 shows a second exemplary embodiment of a pedal travel ^simulator according to the invention in an unactuated state, and Fig. 4 shows the exemplary pedal travel simulator of Fig. 3 in different states of actuation.

In Fig. 1, an exemplary Actuate the ^¬ supply unit 2 for a hydraulic Kraftfahrzeugbremsan ^¬ location of the type 'brake-by-wire "or hydraulic Fremdkraft- illustrated brake system very schematically. Actuator unit 2 comprises an operable by an actuating or brake pedal 1 dual-circuit master brake cylinder or tandem master cylinder 3 and a cooperating with the master brake cylinder 3 pedal travel simulator 4. master brake cylinder 3 comprises two in a housing 5 in tandem arrangement, pistons 6, 7 which two hydraulic pressure chambers 8, limit 9 in ei ^¬ ner exemplary motor vehicle brake system, the pressure chambers are provided. 8 , 9 on the one hand, in the piston 6, 7 are formed radial bores, and corresponding ^¬ Druckaus ^¬ equal lines 10, 11 not shown with a

Pressure medium reservoir in connection, which can be shut off by a relative movement of the pistons 8, 9 in the housing 5. On the other hand, the pressure chambers 8, 9 by means of hydraulic lines I, II, advantageously with the interposition of one, eg normally open, isolation valve per brake circuit and / or individual wheel-electrically controllable Druckmodulationsventilen (eg, an intake and exhaust valve per wheel), with the not ^{dargestell ¬} th wheel brakes of the brake system in conjunction. Preferably, each brake circuit I, II associated with two hydraulically actuated wheel brakes. Furthermore, the pressure chambers 8, 9 unspecified return springs, which position the pistons 6, 7 with unoperated master cylinder 3 in a starting position. A piston rod 12 couples the pivotal movement of the brake pedal 1 due to a Pedalbetä ^¬ actuating the translational motion of the first (Hauptzylin- der-) piston 6, the actuation of which is detected by a ^{vorzugswei ¬} se redundant displacement sensor 13. Since ^¬ by the corresponding Kolbenwegsignal is a measure of the brake pedal depression angle. It represents a brake ^¬ desire a vehicle driver.

The exemplary, not shown motor vehicle ^¬ brake system further comprises an electrically controllable

Pressure source which is hydraulically connected to the brake circuits or wheel brakes of the brake system. The electrically controllable pressure source is preferably designed as a hydraulic cylinder-piston arrangement or as a single-rotor electric-hydraulic actuator whose piston can be actuated by an electric motor with the interposition of a rotational-translational gear. In a normal brake ^¬ function of the brake system ("brake-by-wire" mode) is the master cylinder 3, and thus the driver, decoupled from the wheel brakes by closing the isolation valves and a Simulatorfreigabeventil 15 is activated, which the master cylinder 3, the pedal travel 4 The pedal travel simulator 4 which cooperates with the master brake cylinder 3 then gives the driver a pleasant pedal feel.

According to the example is the pedal travel simulator 4 through the elekt ^¬ driven simulator operable release valve 15 hydraulically connected to the first pressure chamber 8 of the master brake cylinder 3

coupled. But it is also possible that the two pressure chambers 8, 9 of the master cylinder are hydraulically connected to the Pedalwegsi ^¬ mulator or that in each case a pedal travel simulator to each of the two Druckräu- me is connected. By means of the simulator release valve 15, the pedal travel simulator 4 can be switched on or off. In a brake pedal operation and activated (open) simulator release valve 15 (for example in ( 'brake-by-wire "mode) pressure medium flows from the master cylinder pressure chamber 8 in at least one of the hydraulic simulator spaces 16 described below, 26 of Pedalwegsimula ^¬ tors. 4 the thereby generated pedal feel depends on the built-up in the simulator 4 back pressure and of the throttle properties of the activated simulator release valve 15th a hydraulically anti arranged in parallel to the simulator release valve 15 check valve 25 allows independent of the switching state of the simulator cut-off valve 15 and inde ^¬ gig of its throttle effect a largely unimpeded backflow of the pressure means of the simulator spaces 16, 26 8 to the master cylinder pressure chamber the resulting undamped releasing the brake pedal 1 is as pleasant emp ^¬ found. Without this feature, the impression of so-called "sticky" could brake.

According to the first exemplary embodiment of a pedal travel simulator illustrated in FIG. 1, the pedal travel simulator 4 is designed in two parts. A first unit 14 consisting We ^¬ sentlichen from a simulator chamber 16, a

Simulator spring chamber 17 and a two spaces 16, 17 from each other separating simulator piston 18, wherein

Simulator space 16 by means of the simulator release valve 15 with the pressure chamber 8 is connectable. By way of example, simulator piston 18 is guided in housing 5 and bounded by housing 5 simulator space 16 and simulator spring space 17.

Simulator piston 18 is supported by a in

Simulator spring 17 arranged elastic element 19 (eg a spring), which is advantageously biased is, on the housing 5 from. In the simulator unit 14 the generated force-path characteristic is (perceived by the driver Pe ^¬ dalcharakteristik, pedal force as a function of the pedal travel) substantially by the spring characteristic of the resilient member 19, but also for example by frictional forces of the simulator piston 18 or the piston 6, 7 , certainly. It has been shown that in the highly sensitive for the driver initial range of the pedal characteristics, ie at low pedal forces, when using the unit 14 alone certain discontinuities (force jumps) due to the on ^¬ speaking behavior of the simulator spring 19 (eg set too high spring preload), Friction of the simulator piston 18 in the housing 5 and stick-slip effects of the piston seal ^¬ ring 20 result.

Therefore, according to the first embodiment of pedal travel simulator 4 comprises a second unit 24, unit 24 represents ei ^¬ NEN smoothly responsive volume consumer, which is connected to the simulator circuit 21st Unit 24 leads to a smearing of the force jumps and thus to a perceived by the driver as a continuous force-displacement characteristic. Unit 24 comprises a second hydraulic simulator space 26 for receiving pressure medium, which is delimited by a deformable membrane 32.

As can be seen in FIG. 1, comprises essentially the simulator unit 24, a housing 30, which may also be integral with the housing 5, with ei ^¬ nem, for example cylindrical, hollow space defined by the resiliently deformable membrane 32 into two spaces 26, 27 is separated. The hydraulic simulator room 26 is hydraulically connected via line 22 to the simulator circuit 21, and thus also to the simulator room 16 of the unit 14. The simulator unit 24 is hydraulically connected in parallel as jerk-free responding volume consumers of the simulator unit 14 and integrated into the simulator circuit 21 which is connected to the master brake cylinder 3 via the simulator release valve 15 in the "brake-by-wire" mode of operation Suction volume receiving space 27 is connected via line 23 to the

Simulator spring chamber 17 of the unit 14 and its (not shown in Fig. 1) ventilation port with the atmosphere in conjunction. A simulator space 26 unilaterally limiting lid 33 allows the assembly of the unit 24. In receiving space 27, a membrane support body 31 is arranged, the inner contour 34 is suitable for at least partially abutment of the membrane 32. Membrane 32 and inner contour 34 of the membrane support body 31 are designed such that behave the receiving volume of the simulator space 26 and the associated simulator pressure according to the desired force-displacement characteristic. This behavior is achieved by the shaping design of the membrane 32 and the inner contour 34.

At the beginning of braking in the "brake-by-wire" mode, pressure medium displaced from the pressure chamber 8 is first received in the simulator hydraulic space 26 of the simulator unit 24, whereby the deformable diaphragm 32 expands more and more second simulator chamber 16, 26 taken when the external contour of the diaphragm 32 comes to bear against the inner contour 34 of the membrane support body 31., this is achieved maximum absorbable by volume consumer 24 pressure medium volume. There is no further volume increase by a ^¬ unit 24 longer possible. the displaced pressure medium is then only from the first simulator space 16 of

Simulator unit 14 was added. The force-way Characteristic is then determined in the following for increasing pedal travel through the simulator spring 19 of the unit 14. By integrating a jerk-responsive volume consumer 24 with a limited by an elastic membrane 32 simulator space 26 in the pedal travel 4, the often criticized by drivers unsteady force-travel characteristics of the operating unit 2 in the initial area (small pedal paths) is harmonized and thereby improved. The measures according to the invention are simple and inexpensive to produce.

The deformable membrane is preferably formed by an elastomeric membrane. Other membrane solutions, e.g. a metal membrane, however, are also conceivable.

Pedal travel simulator 4 can also be designed as an independent module.

In Fig. 2, the unit 24 of the pedal travel simulator 6 of Fig. 1 is shown in an exploded view. In a bore in the housing 30, the membrane support body 31, the elastically deformable membrane 32 and the cover 33 are successively arranged.

In Fig. 3, a second embodiment of a pedal ^¬ path simulator is shown schematically. The pedal travel ^{simulation ¬} tor is in an unactuated state. Pedal travel simulator 104 includes a housing 105 which receives a simulator piston 118 in a, for example stepped, bore.

Simulator piston 118 has, for example according to a smooth Zylin ^¬ the surface, which interacts with a housing-fixed sealing ring 120th Sealing ring 120 subdivides the bore into a first simulator space 116 and a simulator ^spring space 117, the simulator spring space 117 corresponding to the desired, advantageously progressive, force-displacement characteristic (simulator characteristic) corresponding non-linear

Simulator spring 119 receives. Simulator spring chamber 117 is connected to atmospheric pressure via a ventilation connection 140 and is filled either with air or with pressure medium (at atmospheric pressure = "depressurized.") Simulator space 116 can be connected via a hydraulic connection 141 to, for example, a brake pedal-actuated master brake cylinder, so that simulator space 116 In this case, the volume of the first simulator space 116 changes by displacing the simulator piston 118 relative to the housing 105. In its unpressurised rest position (pressure in the hydraulic port 141 is equal to the pressure in the ventilation port 140) Simulator flask 118 from

Simulator spring 119 frontally pressed against a stop in the housing 105. To avoid a "slack" pedal feel when releasing the brake pedal, the biasing force of

Simulator spring 119 usually chosen sufficiently large. This has the consequence that when pressing the brake pedal to ^¬ next pressure must be built, the force on the simulator piston 118, the biasing force of the

Simulator spring 119 and the static frictional force of the sealing ring 120 overcomes before the pedal travel 104 absorbs pressure medium volume in the simulator 116 space. This "breaking away" of the simulator piston 118 is noticeable in known Simula ^¬ tor brake systems as an undesirable jerk in the brake pedal.

In order to improve the response of the Pedalwegsimula ^¬ gate 104 and to prevent the breakaway effect described above is an additional in simulator piston 118, arranged smoothly responsive volume absorption. This is designed as a second simulator space 126 whose volume can be changed by the deformation of a membrane 132 made of an elastic material. The deformation of an elastic membrane 132 is practically

hysteresis-free, ie without causing the undesired jerk in Bremspe ^¬ dal. The deformable membrane is thus integrated according to the second embodiment in the simulator piston.

Membrane 132 separates in simulator piston 118

Simulator space 126 from a swallowing volume receiving space 127. receiving space 127 is depressurized, since it is connected via one or more ventilation channels 145 with the simulator spring chamber 117. The second simulator room 126 is connected to the first via at least one connection channel 146

Simulator room 116 connected.

By way of example, the attachment of the membrane 132 in the simulator piston 118 is effected by a in the front of the

Simulator piston 118 pressed-piston front cover 133, which limits the simulator space 126 together with the diaphragm 132. By pressing in the membrane 132 is fixed pressure-tight at its outer periphery annular. In piston end cap 133 with a housing 105 zusammenwir ^¬ kende stop surface 148 and the communication passage 146 from the first simulator chamber 116 are formed for the second simulator chamber 126th Furthermore, the piston end cover 133 to the second simulator space 126 toward a pin-shaped rotational contour 147, on which the diaphragm 132 in the unpressurized

(unactuated) state of the simulator 104 at least partially ^¬ rests, so that the volume of the second

Simulator space 126 in this state, the value zero or almost zero.

4 shows the example pedal travel simulator 104 in various states of actuation. If the pedal travel simulator 104 is actuated, the diaphragm 132 initially deforms, as shown in FIG. 4 a, ie pressure medium is received in the second simulator space 126. Membrane 132 moves into the pressureless receiving space 127, the filling volume (air or pressure medium) of which is displaced by the ventilation channels 145 leading to the simulator spring space 117. Thus, Fig. 4a shows the pedal travel simulator 104 in the transition phase of the soft start of the acquisition to Volumenauf ^¬ start running the simulator envelope 118.

Upon further actuation of the brake pedal, both the first and the second simulator space 116, 126 take up pressure medium. Accordingly, FIG. 4b shows the pedal ^{travelimulator} 104 with a moved simulator piston 118 with the diaphragm 132 not yet fully applied to a hollow contour 134 in the simulator piston 118.

When the volume of the receiving space 127, he ^¬ reaches the value zero or the Simulatoraum 126 has reached its maximum possible receiving volume, the membrane is applied to the corresponding hollow contour 134 in the simulator piston 118 132nd The simulator piston 118 thus acts in this embodiment as a membrane support body. A volume acquisition then takes place exclusively in the first simulator space 116 by moving the simulator piston 118. 104 of this was to ^¬ of the pedal travel at higher pressure is shown in Fig. 4c.

Desirable effect of gentle transition from unpressurized State of the simulator 104 to an operating state in which the stop surface 148 of the simulator piston 118 has detached from the housing 105 can be predetermined by the shape of the movement limiting contours 147, 134 for the diaphragm 132.

The arrangement of the second simulator space 126 for displaying the smoothly responding additional volume in the simulator piston 118 according to the second embodiment, in contrast to the first embodiment in the housing 105 no further bore for connecting the two simulator rooms needed.

By combining the rotary parts simulator piston 118, Schmiegekonturen 134, 147 and clamping the Ansprechmembran 132 according to the second embodiment in a ^¬ construction part, the design effort is also minimized.

The pedal travel simulator 104 according to the second exemplary embodiment is also preferably used in an operating unit or a hydraulic brake system of the "brake-by-wire" type, as explained in connection with FIG. 1. In this case, pedal travel simulator 104 is advantageously provided with an electromagnetically operable, in particular ^¬ sondere normally closed, simulator release valve to be switched ^¬ which is attached ^¬ arranged in a hydraulic connection between a pressure chamber of the master brake cylinder and the hyd ^¬ raulischen port 141 of the pedal travel 104th

Claims

Claims:

1. pedal travel simulator (4, 104) for hydraulic connection to a pressure chamber (8) of a master brake cylinder (3) of a hydraulic brake system, in particular for motor vehicles, a housing (5, 30, 105) and a displaceably mounted in the housing simulator piston (18 , 118), wherein the simulator piston with the housing delimits a first hydraulic simulator space (16, 116), which can receive pressure medium, wherein the simulator piston (18, 118) is acted upon by an elastic return means (19, 119), characterized in that the pedal travel simulator (4, 104) comprises a second hydraulic simulator space (26, 126) for receiving pressure medium, which is delimited by an elastically deformable membrane (32, 132).

2. pedal travel simulator according to claim 1, characterized in that a deformation of the membrane (32, 132) by at least one limiting contour (34, 134, 147) of a membrane support body (31, 118, 133) in particular of the simulator piston (118) is limited in space ,

3. pedal travel simulator according to claim 2, characterized in that the membrane support body (31, 118), in particular the simulator piston (118), and the membrane (32, 132) defining a receiving space (27, 127), which in particular is connected to atmospheric pressure.

4. pedal travel simulator according to claim 3, characterized in that the elastic return means (19, 119) in a space (17, 117) is arranged, which of the simulator piston (18, 118) and the housing (5, 105) Be is bordered and which opposite to the first

Simulator space (16, 116) is sealed (20, 120), wherein the space (17, 117) is connected to atmospheric pressure and / or via at least one connecting line (23, 145) with the receiving space (27, 127) is connected, which connected to atmospheric pressure.

Pedal travel simulator according to one of claims 1 to 4, characterized in that it comprises at least one Ver ^{¬ connecting line} (22, 146) through which the first and the second simulator space (16, 26, 116, 126) are hydraulically connected to each other.

Pedal travel simulator according to one of claims 1 to 5, characterized in that the pedal travel simulator (4) comprises two, in particular in a common housing (5) to ^¬ ordered, spatially separated units (14, 24), wherein the first unit (14) the first

Simulator space (16) and the simulator piston (18) and the second unit (24) the second simulator space (26) and the elastically deformable membrane (32).

Pedal path simulator according to one of claims 1 to 5, characterized in that the second simulator space (126) in a cavity of the simulator piston (118), in particular in the return means (119) against ^¬ overlying region of the simulator piston (118) is arranged.

A pedal travel simulator according to claim 7, characterized in that the second simulator space (126) of the arranged in the simulator piston (118) membrane (132) and a, in particular pressed, piston end cover (133) of the simulator piston (118) is limited.

9. pedal travel simulator according to claim 8, characterized in that in the Kolbenstirndeckel (133) a connec tion ^¬ duct (146) is arranged, via which the two ^¬ th simulator space (126) with the first simulator space (116) is hydraulically connected.

10. Pedalwegsimulator according to claim 8 or 9, characterized in that on the piston end cover a Be ^¬ boundary contour is formed, to which the membrane is applied in an unactuated state of the pedal travel substantially.

11. pedal travel simulator according to one of claims 7 to 10, characterized in that in the cavity of the simulator piston (118) is a receiving space (127), which of the membrane (132) and one in the

Simulator piston (118) formed boundary contour

(134) is limited.

12. pedal travel simulator according to claim 11, characterized in that the receiving space (127) via at least one in the simulator piston (118) arranged connecting channel (145) with a the elastic Rückstellmit ^¬ tel (119) receiving space (117) is connected.

13. Actuator for a hydraulic motor vehicle ^¬ brake system of the type "brake-by-wire" with

A master brake cylinder (3) which can be actuated by means of a brake pedal (1) and has at least one pressure chamber (8, 9), can be hydraulically connected to the wheel brakes (I, II), and A pedal travel simulator (4, 104) according to any one of claims 1 to 12, by which, in a brake-by-wire mode, in which the first and second simulator spaces (16, 26, 116, 126) are connected to the pressure space (8) of the main brake cylinder (3) are hydrau ^¬ cally connected one to the brake pedal (1) acting restoring force is simulated.

14. Actuator according to claim 13, characterized in that in the hydraulic connection between the pressure chamber (8) and the pedal travel simulator (4, 104), in particular the first and second simulator space (16, 26, 116, 126), a switching device (15 , 25) is provided, which in the "brake-by-wire" mode the master cylinder (3) the first and second

Simulatorraum switches on and outside the "brake-by-wire" mode disconnects the connection, in particular ^{¬ the} special switching device by an electrically controllable, in particular normally closed, Zuschaltventil (15) and the Zuschaltventil connected in parallel, in the direction of the master cylinder (3 ) opening check valve (25) is formed.

15. Hydraulic motor vehicle brake system, in a

So-called "brake-by-wire" mode of both the vehicle ^¬ leader and independent of the driver

can be controlled, preferably in the "brake-by-wire" - operated mode and can be operated in at least one fallback mode by the driver, with

A master brake cylinder (3) which can be actuated by means of a brake pedal (1) with at least one pressure Spaces (8, 9) to which wheel brakes are hydraulically connected,

• An electrically controllable pressure source, by means of which the wheel brakes can be acted upon with pressure, and which in particular with each of the wheel brakes ^¬ hydraulically connected, and

A pedal travel simulator (4, 104) according to any one of claims 1 to 12, by which in the brake-by-wire mode, in which the first and second simulator spaces (16, 26, 116, 126) are connected to the pressure space (8) of the master cylinder (3) are hydraulically connected ^¬ , the driver a pleasant brake pedal feeling is mediated.