Brake pedal simulator for a braking system and braking system

Abstract

Brake pedal simulator (3) for a brake system (1), wherein the brake pedal simulator (3) has a simulator housing (102, 104) within which a simulator chamber (106) is formed, wherein an elastic element (108) is arranged in the simulator chamber (106), which separates a receiving chamber (110) from a return chamber (112) within the simulator chamber (106) and is designed to deform elastically towards the return chamber (112) when the receiving chamber (110) is pressurized, wherein the receiving chamber (110) has an inlet (114) for connection with a brake actuation unit (2) of the brake system (1), characterized in that the elastic element (108) is disc-shaped and the simulator housing (102, 104) has a funnel-shaped recess (120) in the region of the return chamber (112) for receiving the elastic element (108) when pressure is applied exhibits deformation of the elastic element (108) in the direction of the rear chamber (112).

Description

The invention relates to a brake pedal simulator according to the preamble of claim 1 and to a brake system according to claim 11."Brake-by-wire" brake systems are becoming increasingly widely used in automotive engineering. Such brake systems often comprise, in addition to a master brake cylinder that can be actuated by the vehicle driver, an electrically ("by-wire") actuatable pressure provision device, by means of which actuation of the wheel brakes takes place in the "brake-by-wire" operating mode.In these brake systems, in particular electrohydraulic brake systems with the "brake-by-wire" operating mode, the driver is decoupled from direct access to the brakes. When the pedal is actuated, a pedal decoupling unit and a brake pedal simulator are usually actuated, the driver's braking request being detected by a sensor system. The brake pedal simulator serves to give the driver the most familiar and comfortable feeling of the brake pedal. The detected braking request leads to the determination of a setpoint braking torque, from which the setpoint braking pressure for the brakes is determined. The brake pressure is then actively built up by a pressure provision device in the brakes.The actual braking thus takes place by active pressure build-up in the brake circuits with the aid of a pressure provision device which is controlled by a control and regulating unit. Due to the hydraulic decoupling of the brake pedal actuation from the pressure build-up, many functionalities such as ABS, ESC, TCS, slope driving aid, etc. can be implemented comfortably for the driver in such brake systems.The brake pedal simulator in such a brake system simulates the hydraulic back pressure at the driver's brake pedal during braking. The force-travel characteristic curve of the brake pedal simulator can be adapted to the characteristic curve of a brake booster in order to still give the driver the brake feel of a conventional brake system. This characteristic curve is characterized by the travel of the piston rod and the required foot force.The desired force-travel characteristic curve is often generated by a combination of a plurality of elastically deformable elements, the dimensions and arrangement of which are adapted such that the restoring force caused when the elements are deformed follows the desired force-travel characteristic curve. As elastic elements, steel springs, rubber bodies or the like are usually used, which have to be manufactured with high precision and arranged in the brake pedal simulator in order to ensure the desired functionality.DE 10 2012 203 099 A1 describes, by way of example, such a pedal travel simulator having a housing and a simulator piston mounted displaceably in the housing, wherein the simulator piston together with the housing delimits a first hydraulic simulator chamber which can accommodate pressure medium. The simulator piston is acted upon by an elastic restoring means. Furthermore, the pedal travel simulator comprises a second hydraulic simulator chamber for receiving pressure medium, which is bounded by an elastically deformable diaphragm.In contrast, the objective technical object of the present application is to provide an improved brake pedal simulator and an improved brake system having a simplified structure.This object is achieved with the brake pedal simulator according to claim 1 and with the brake system according to claim 11. Advantageous embodiments are specified in the dependent claims 2 to 10.In a first aspect, the invention relates to a brake pedal simulator for a brake system, wherein the brake pedal simulator has a simulator housing, within which a simulator chamber is formed. An elastic element is arranged in the simulator chamber, which separates a receiving chamber from a rear chamber within the simulator chamber and is designed to deform elastically in the direction of the rear chamber when the receiving chamber is pressurized. The receiving chamber has an inlet for connection to a brake actuating unit of the brake system. According to the invention, it is provided that the elastic element is disk-shaped and the simulator housing has a funnel-shaped formation in the region of the rear chamber for receiving the elastic element when the elastic element is deformed in the direction of the rear chamber.By the interaction of a disk-shaped elastic element with the funnel-shaped formation of the rear chamber, an arrangement is created with few components, by means of which an effort-travel characteristic curve that can be formed by appropriate design of the funnel shape can be provided. If, during a braking maneuver, the receiving chamber is pressurized by the brake fluid of the brake system, the elastic element deforms in the direction of the rear chamber. As long as the elastic element does not abut on the funnel-shaped formation of the housing, the elastic element only brings about a slight restoring force on the brake fluid. The corresponding course of the force-displacement characteristic curve corresponds to the course which would be expected in a classic brake system as long as the brake pads do not yet bear against the brake disc of the brake system. However, as the deformation of the elastic member increases, the restoring force applied from the elastic member to the brake fluid increases exponentially from a certain point. On the one hand, the elastic element rests via surfaces that become increasingly larger on the funnel-shaped formation of the housing and is consequently compressed into itself. On the other hand, the tension of the elastic member increases more and more in the radial direction of the disk shape.The exact course of the force-displacement characteristic curve can be formed on the one hand by the design of the elastic element, for example its thickness, diameter and material quality, and on the other hand by the shape of the funnel-shaped formation.A further advantage of the brake pedal simulator according to the invention is that no metallic elements are displaced in the simulator, so that contact noises when metallic elements meet are avoided. Furthermore, the complexity of the design is significantly reduced compared to known simulators having a multiplicity of elastic elements, which simultaneously benefits the overall height of the brake pedal simulator.According to a preferred embodiment, the desired force-displacement characteristic curve is achieved in that a wall gradient of the funnel-shaped formation varies along an axis perpendicular to the elastic element. For example, the funnel shape may initially have relatively flat walls which run almost parallel to the disk shape, so that the elastic element comes into rapid contact with the surfaces of the funnel shape upon an initial application of a force in the direction of the rear chamber. Subsequently, in order to prevent an excessively large increase in the restoring force caused by the elastic member, the pitch of the funnel shape along the axis perpendicular to the elastic member may further increase, so that the tension of the elastic member may further increase in the radial direction of the disk shape and the elastic member may be less strongly compressed therein in the axial direction. In this case, both discrete regions can be provided in which the funnel shape has a uniform gradient and continuous profiles of the gradient of the funnel shape.In this case, the simulator housing according to a preferred embodiment is composed of two housing parts, wherein the elastic element is held between the housing parts in a force-fitting and / or form-fitting manner. For example, the elastic element can be clamped between the housing parts during the mounting of the housing parts to one another.Preferably, the rear chamber is formed exclusively between the elastic element and one of the housing parts, wherein the funnel-shaped formation is also formed in this housing part. In this way, the characteristic of the simulator, i.e. the generated force-displacement characteristic curve, can be changed by replacing this housing part with a housing part having a differently configured funnel-shaped formation.In order to obtain a defined zero position of the brake pedal simulator or of the elastic element, it is provided according to a further embodiment that the elastic element is prestressed in the radial direction of the disk shape. This prestress is preferably generated during the mounting of the elastic element between the housing parts.According to a preferred embodiment, it is further provided that an electrically actuatable actuator device is arranged in or on the simulator housing, which is designed to bring about an adjustable prestress of the elastic element in the axial and / or radial direction of the disk shape. This makes it possible, by appropriate actuation of the actuator device, to change the force-travel characteristic curve of the brake pedal simulator without the brake pedal simulator having to be disassembled. For example, different characteristics of the force-displacement characteristic curve can thus also be realized for different driving modes of a vehicle, for example sport or comfort mode. In this case, the actuator device can both subject the elastic element to a permanently constant prestress and can change the prestress depending on the situation during operation of the brake pedal simulator.A particularly simple and simultaneously precisely controllable variant of such an actuator device is provided according to one embodiment in that the actuator device has an electromagnet with a coil and a ferromagnetic armature, wherein the armature is fastened to the elastic element and the coil is fastened in or on the simulator housing. By appropriate energization of the coil, an electromagnetic force can thus be exerted on the armature, which force brings about a prestress of the elastic element by the fastening of the coil to the housing on the one hand and the armature to the elastic element on the other hand. The type of prestressing can be determined by appropriate positioning of the armature and of the coil relative to one another.According to one embodiment, a particularly robust construction is achieved in that the anchor is connected to the elastic element in a form-fitting manner.It is particularly advantageous if the anchor according to a further embodiment is cast at least in sections into the elastic element, whereby a particularly robust connection is produced between anchor and elastic element. For this purpose, the anchor can have a T-shaped formation, for example, at its end facing the elastic element, wherein the T-shape is completely cast into the elastic element.According to a further embodiment, the armature is at least partially rod-shaped, wherein the coil has a recess in which the rod-shaped portion of the armature is guided. This allows more precise control of the prestress of the elastic element, since at all times the guidance of the armature determines how the force exerted by the armature on the elastic element is directed.A particularly maintenance-friendly design of the brake pedal simulator is achieved according to a further embodiment in that the coil is arranged outside the rear chamber, wherein the simulator housing has a guide opening in the region of the rear chamber, through which the armature is guided into the coil. Preferably, the coil is enclosed in a further housing which is fastened to the simulator housing. For servicing the coil, the brake pedal simulator per se does not have to be disassembled, which is advantageous in particular when fastening the elastic element under prestress between the housing halves.In a further aspect, the invention relates to a brake system having a brake actuating unit which can be actuated by a brake pedal and a brake pedal simulator as has been described above.Preferred exemplary embodiments are explained in more detail below with reference to the figures. The following are shown: FIG. 1 is a circuit diagram of a brake system, FIG. 2 shows a detailed view of a brake pedal simulator, FIG. 3 shows a simulation of the behavior of the brake pedal simulator when pressure is applied, FIG. 4 shows a detailed view of the funnel-shaped recess of the rear chamber, and FIG. 5 shows a detailed view of a further variant of a brake pedal simulator.In the following, features that are similar or identical to one another are identified by the same reference numerals.FIG. 1 shows an exemplary embodiment of a brake system 1 according to the invention on the basis of a circuit diagram. The brake system 1 comprises a master brake cylinder 2 as a brake actuation unit, which can be actuated by means of an actuation or brake pedal 1 a, a brake pedal simulator 3 which interacts with the master brake cylinder 2, a pressure medium storage container 4 which is assigned to the master brake cylinder 2 and is at atmospheric pressure, an electrically controllable pressure provision device 5, which is formed by a cylinder-piston arrangement having a hydraulic pressure chamber 37, the piston 36 of which can be displaced by an electromechanical actuator, an electrically controllable pressure modulation device for setting wheel-specific brake pressures, and an electronic control and regulating unit 12.The pressure modulation device, which is not designated in more detail, comprises, for example, an inlet valve 6 a- 6 dand an outlet valve 7 a- 7 d, respectively, for the hydraulically actuatable wheel brakes 8, 9, 10, 11, which are hydraulically connected together in pairs via central connections and are connected to the wheel brakes 8, 9, 10, 11. The input connections of the inlet valves 6 a- 6 dare supplied with pressures by means of brake circuit supply lines 13 a, 13 b, which pressures are derived from a system pressure, which is present in a system pressure line 38 connected to the pressure chamber 37 of the pressure provision device 5, in a "brake-by-wire" operating mode. The brakes 8, 9 are hydraulically connected to a first brake circuit 27, and the brakes 10, 11 are hydraulically connected to a second brake circuit 33.A check valve 50 a- 50 dis connected in parallel with the inlet valves 6 a- 6 d, opening toward the brake circuit supply lines 13 a, 13 b. In a fallback operating mode, the brake circuit supply lines 13 a, 13 bare acted upon by the pressures of the pressure chambers 17, 18 of the master brake cylinder 2 via hydraulic lines 22 a, 22 b. The outlet connections of the outlet valves 7a-7d are connected to the pressure medium reservoir 4 via a return line 14b.The master brake cylinder 2 has in a housing 21 two pistons 15, 16 arranged one behind the other, which delimit the hydraulic pressure chambers 17, 18. The pressure chambers 17, 18 are connected on the one hand to the pressure medium reservoir 4 via radial bores formed in the pistons 15, 16 and corresponding pressure compensation lines 41 a, 41 b, wherein the connections can be shut off by a relative movement of the pistons 17, 18 in the housing 21. The pressure chambers 17, 18 are on the other hand connected by means of the hydraulic lines 22 a, 22 bto the already mentioned brake circuit supply lines 13 a, 13 b.The pressure compensation line 41a contains a normally open valve 28. The pressure chambers 17, 18 receive restoring springs, not designated in any more detail, which position the pistons 15, 16 in a starting position when the master brake cylinder 2 is not actuated. A piston rod 24 couples the pivoting movement of the brake pedal 1 aas a result of a pedal actuation to the translatory movement of the first master brake cylinder piston 15, the actuation travel of which is detected by a travel sensor 25, which is preferably of redundant design. As a result, the corresponding piston travel signal is a measure of the brake pedal actuation angle. It represents a braking request of the vehicle driver.In each of the line sections 22 a, 22 bconnected to the pressure chambers 17, 18, a separating valve 23 a, 23 bis arranged, which is designed as an electrically actuatable, preferably normally open, 2 / 2-way valve. The hydraulic connection between the pressure chambers 17, 18 of the master brake cylinder and the brake circuit supply lines 13 a, 13 bcan be shut off by the isolation valves 23 a, 23 b. A pressure sensor 20 connected to the line section 22 bdetects the pressure built up in the pressure chamber 18 by displacement of the second piston 16.The brake pedal simulator 3 shown only schematically in FIG. 1 is hydraulically couplable to the pressure chamber 17 of the master brake cylinder 2. When a pedal force is preset and the simulator valve 32 is open, pressure medium flows from the master cylinder pressure chamber 17 into the simulator chamber 29, and a nonreturn valve 34, which is arranged hydraulically antiparallel to the simulator valve 32, permits a largely unimpeded return flow of the pressure medium from the simulator chamber 29 to the master cylinder pressure chamber 17, regardless of the switching state of the simulator valve 32, and other embodiments and connections of the pedal simulator to the master cylinder 2 are conceivable. The brake pedal simulator 3 is preferably constructed as described in connection with FIG. 2 or 5.The electrically controllable pressure provision device 5 is designed as a hydraulic cylinder-piston arrangement or a single-circuit electrohydraulic actuator, the pressure piston 36 of which, which delimits the pressure chamber 37, can be actuated by an electric motor 35 which is indicated schematically, with the interposition of a rotation-translation gear which is likewise illustrated schematically. A rotor position sensor, which is used to detect the rotor position of the electric motor 35 and is indicated only schematically, is denoted by the reference symbol 44. In addition, a temperature sensor for sensing the temperature of the motor winding may also be used.The actuator pressure generated by the force effect of the piston 36 on the pressure medium enclosed in the pressure chamber 37 is fed into the system pressure line 38 and detected with a pressure sensor 19, which is preferably designed redundantly. When the sequence valves 26 a, 26 bare open, the pressure medium reaches the wheel brakes 8, 9, 10, 11 for actuation thereof. By pushing the piston 36 forward and backward, with the cut-off valves 26 a, 26 bopen, during normal braking in the brake-by-wire operating mode, a wheel brake pressure build-up and decrease takes place for all wheel brakes 8, 9, 10, 11.In contrast, during braking with wheel brake pressures that are different for each wheel and controlled with the aid of the inlet and outlet valves 6 a- 6 d, 7 a- 7 d(e.g. during anti-lock control (ABS control), the pressure medium portion discharged via the outlet valves 7 a- 7 dflows into the pressure medium reservoir 4 and is thus initially no longer available to the pressure provision device 5 for actuating the wheel brakes 8, 9, 10, 11. A re-suction of pressure medium into the pressure chamber 37 is possible by a return movement of the piston 36 with closed switch-on valves 26 a, 26 bvia a re-suction line 56, into which a non-return valve 58 is connected, which prevents the return flow of pressure medium from the pressure chamber into the pressure medium storage container 4.FIG. 2 shows a detailed view of the brake pedal simulator 3 indicated only schematically in FIG. 1, the brake pedal simulator 3 essentially comprising a simulator housing formed by two housing parts 102 and 104, within which a simulator chamber 106 is formed. A disc-shaped elastic element 108 of thickness D is clamped between the housing parts 102 and 104, which preferably consists of an elastomer. For a secure fastening of the elastic element 108, it can be provided that the elastic element 108 forms a positive fit (not shown) with the housing parts 102 and 104 in its edge regions. The effective diameter d of the elastic element 108, which contributes to the elastic behavior of the elastic element 108, extends over the region of the elastic element 108 that is not clamped between the housing parts 102 and 104.The elastic element 108 has a prestress in the radial direction of the elastic element, as a result of which the elastic element 108 remains in a defined rest position without application of a force perpendicular to its disk shape. FIG. 2 illustrates just this non-exposed rest position of the elastic element 108.The simulator chamber 106 is divided into a receiving chamber 110 and a back chamber 112 by the elastic member 108. The receiving chamber 110 is formed between the elastic element 108 and the upper housing part 106, wherein an inlet 114 is formed in the upper housing part 102, via which inlet the receiving chamber 110 can be connected to the brake actuating unit 2 of the brake system 1.In the region of the rear chamber 112, the housing part 104 delimiting the rear chamber 112 has an opening 116, through which the rear chamber 112 is connected to the environment. Consequently, atmospheric pressure always prevails within the back chamber 112 in the embodiment shown. Alternatively, the back chamber 112 can also be filled with a brake fluid. The shape of the rear chamber is thereby essentially defined by the elastic element 108 on the one hand and a funnel-shaped formation 120 of the inner wall 118 of the housing part 104 on the other hand. The inclination of the funnel shape changes along an axis 122 perpendicular to the elastic element 108When the brake pedal 1 ais operated, the brake fluid located in the master cylinder 2 (see FIG. 1 ) serving as brake actuation unit is pressurized with a pressure which occurs likewise also in the receiving chamber 110 on account of the connection between brake actuation unit 2 and receiving chamber 110 via the inlet 114. Due to the pressure difference thus arising between receiving chamber 110 and rear chamber 112, elastic element 108 is acted upon by a force in the direction of rear chamber 112. As a result, the elastic element 108 deforms in the direction of the receiving chamber, whereby tensile and compressive stresses arise within the elastic element 108, which counteract the pressure generated by actuation of the brake pedal 1 aand cause the desired force-travel characteristic curve for the actuation of the brake pedal 1 a. At the same time, the volume of the accommodation chamber 110 increases, so that the brake pedal 1 acan be displaced along the operation direction.A simulation of the behavior of the elastic element 108 of the brake pedal simulator 3 when the receiving chamber 110 is pressurized is shown in FIG. 3 for different pressures for the geometry of the funnel-shaped formation 120 shown in FIG. 2.In FIG. 3 a), the receiving chamber was subjected to only a low pressure. As a result, the elastic member 108 is only slightly deformed toward the back chamber 112. In this case, a tensile stress is produced in the center of the elastic element 108 on the side of the rear chamber 112, while a compressive stress is produced on the opposite side. Furthermore, a slight compressive stress likewise prevails at the edges of the elastic element 108, that is to say in the regions in which the elastic element 108 adjoins the housing parts 102 and 104, in the region of the rear chamber 112. In this case, the elastic element 108 bears only slightly against the inner wall 118 of the rear chamber 112, with the result that the restoring force generated by the elastic element 108 substantially results from the tensile and compressive stresses mentioned. For a deformation of the elastic element 108 along the axis 122, only a comparatively low force is necessary in this region, so that only a low counterpressure acts on the brake pedal 1 a. This corresponds to that region of the actuation travel of the brake pedal, via which only the clearance of the wheel brake is overcome and consequently only slight counterforces are to be expected when the pedal 1 ais actuated.In FIG. 3 b), the pressure prevailing in the receiving chamber 110 has been increased compared to the situation discussed above by a further actuation of the brake pedal 1 a. The consequence of this is that the elastic element 108 has been displaced further in the direction of the rear chamber 112 and rests over wide surfaces on the inner wall 118 of the rear chamber 112. A further deformation due to a movement of the elastic element 108 in the direction of the rear chamber 112 is only possible to a slight extent, so that a correspondingly large counterforce is generated in the receiving chamber in the event of a further increase in pressure. In comparison with a classic brake system, this corresponds to that region of the displacement travel of the brake pedal 1 a, in which the brake pads of a wheel brake already bear on the brake disc. Consequently, an exponentially increasing counterforce would be expected with a further actuation of the brake pedal, since from this point in time any further displacement of the brake pedal 1 ain the actuation direction can only be achieved by a compression of the brake linings or a deformation of the corresponding elements of the wheel brake.In FIG. 3 c), the pressure in the receiving chamber has now been increased to such an extent that the elastic element 108 rests over its entire surface on the inner wall 118 of the funnel-shaped formation 120. In the event of a further increase in pressure of the receiving chamber 110, an increase in the volume of the receiving chamber 110 can only still take place by a compression of the elastic element 108 against the inner wall 118. Consequently, a very large force must be applied for a small displacement of the brake pedal 1 afrom this time.Effectively, a different profile of the force-displacement characteristic curve of the brake pedal simulator 3 is thus generated for different pressure ranges. While only a slight restoring force prevails in the case of small displacement movements, the restoring force increases increasingly during the further course of a displacement of the brake pedal 1 a. As the elastic element 108 continues to bear further against the inner wall 118 of the return chamber 112, the restoring force finally increases exponentially over the displacement path.The specific profile of this force-displacement characteristic curve is essentially defined by the design of the elastic element (thickness, diameter, material) and by the specific shape of the funnel-shaped formation.For this purpose, the housing part 104 is again shown separately in FIG. 4, on the inner surface of which, that is to say the inner wall 118 of the subsequent rear chamber 112, the funnel-shaped formation 120 is formed. In the embodiment shown in FIG. 4, the formation 120 essentially has four regions, which each have different wall slopes relative to the axis 122. By selecting the ranges and the corresponding wall slopes, the force-travel characteristic curve of the brake pedal simulator 3 can be influenced in the desired manner. In addition to the illustrated course of the wall slope with discrete regions of different slopes, the wall slope can also change continuously over the entire length of the inner wall 118.FIG. 5 shows a further variant of a brake pedal simulator 3, the structure of which is largely identical to the brake pedal simulator 3 described above with reference to FIG. 2. However, the brake pedal simulator 3 of FIG. 5 differs in that an electrically actuatable actuator device is arranged on the simulator housing or the lower housing part 104. According to the example, this is essentially composed of an armature 202 fastened to the elastic element 108 and a coil 204 fastened to the housing part 104. The rod-shaped armature 202 is made of a ferromagnetic material and is embodied in a T-shaped manner at its upper end 206. The T-shape is embedded, for example cast, in the elastic element 108 and produces a positive connection between the anchor 202 and the elastic element 108. The coil 204 is supported in a separate housing 208 which, in turn, is secured to the housing portion 104.If the coil 204 is energized, it generates a magnetic field which, depending on the polarity, either repels the ferromagnetic armature 202 in the direction of the receiving chamber 110 or attracts it in the direction of the recess 210 of the coil 204. Effectively, when the coil 204 is energized, a force is thus exerted on the elastic element 108, which force can either reinforce or reduce a deformation of the elastic element 108 due to a pressurization. Consequently, with this arrangement, a biasing of the elastic member 108 can be caused, by which the force-displacement characteristic generated by the brake pedal simulator 3 can be influenced.In order to ensure reliable operation of the actuator device, the armature 202 is guided in a guide opening 212 which is formed in the region of the rear chamber 112 in the housing part 104. Together with the guidance of the armature 202 in the recess 210 of the coil, tilting of the armature 202 can thus be effectively prevented.

Claims

Brake pedal simulator (3) for a brake system (1), wherein the brake pedal simulator (3) has a simulator housing (102, 104), within which a simulator chamber (106) is formed, wherein an elastic element (108) is arranged in the simulator chamber (106), separates a receiving chamber (110) from a rear chamber (112) within the simulator chamber (106) and is designed to deform elastically in the direction of the rear chamber (112) when the receiving chamber (110) is pressurized, wherein the receiving chamber (110) has an inlet (114) for connection to a brake actuating unit (2) of the brake system (1), characterized in that the elastic element (108) is of disc-shaped design and the simulator housing (102, 102, 102, 104) in the region of the rear chamber (112) have a funnel-shaped formation (120) for receiving the elastic element (108) upon deformation of the elastic element (108) in the direction of the rear chamber (112).Brake pedal simulator (3) according to Claim 1, characterized in that a wall gradient of the funnel-shaped formation (120) varies along an axis (122) perpendicular to the elastic element (108).Brake pedal simulator (3) according to Claim 1 or 2, characterized in that the simulator housing (102, 104) is composed of two housing parts (102, 104), the elastic element (108) being held between the housing parts (102, 104) in a force-fitting and / or form-fitting manner.Brake pedal simulator (3) according to one of the preceding claims, characterized in that the elastic element (108) is prestressed in the radial direction of the disc shape.Brake pedal simulator (3) according to one of the preceding claims, characterized in that an electrically actuatable actuator device (202, 204) is arranged in or on the simulator housing (102, 104), said actuator device being designed to bring about a regulable prestress of the elastic element (108) in the axial and / or radial direction of the disc shape.Brake pedal simulator (3) according to Claim 5, characterized in that the actuator device (202, 204) has an electromagnet having a coil (204) and a ferromagnetic armature (202), the armature (202) being fastened to the elastic element (108) and the coil (204) being fastened in or to the simulator housing (102, 104).Brake pedal simulator (3) according to Claim 6, characterized in that the armature (202) is connected in a positively locking manner to the elastic element (108).Brake pedal simulator (3) according to Claim 7, characterized in that the armature (202) is cast at least in sections into the elastic element (108).Brake pedal simulator (3) according to one of Claims 6 to 8, characterized in that the armature (202) is of rod-shaped design at least in sections, the coil (204) having a recess (210) in which the rod-shaped section of the armature (202) is guided.Brake pedal simulator (3) according to one of Claims 6 to 9, characterized in that the coil (204) is arranged outside the rear chamber (112), the simulator housing (102, 104) having, in the region of the rear chamber (112), a guide opening (212), through which the armature (202) is guided into the coil (204).Brake system (1) having a brake actuating unit (2) which can be actuated by a brake pedal (1a) and a brake pedal simulator (3) according to one of the preceding claims.

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