Wheel brake for a motor vehicle

Abstract

The invention relates to a wheel brake (10) for a motor vehicle, comprising a first brake element (12) having a first friction surface (14), and a brake disc (20) as a second brake element, rotatably mounted on a wheel carrier (18) about an axis of rotation (16) or mounted and rotatable about the axis of rotation (16) relative to the first brake element (12), which is displaceable along the axis of rotation (16) relative to the first brake element (12) and has a second friction surface (28) facing the first friction surface (14) along the axis of rotation (16) and a third friction surface (32) facing away from the first friction surface (14) and the second friction surface (28) along the axis of rotation (16), which faces away from the first friction surface (16) and the second friction surface (28) along the axis of rotation (16) and faces a fourth friction surface (36) of a third brake element (64) of the wheel brake (10). is,whose third brake element (34) can be moved towards the second brake element and the first friction surface (14) by actuating the wheel brake (10) along the axis of rotation (16).

Description

The invention relates to a wheel brake for a motor vehicle. DE 2 018 557 A1 describes a device for indicating wear of a friction lining as known. The object of the present invention is to create a particularly advantageous wheel brake for a motor vehicle. This problem is solved by a wheel brake with the features of claim 1. Advantageous embodiments with expedient further developments of the invention are specified in the dependent claim. The invention relates to a wheel brake designed as a friction brake, and in particular as a disc brake, for a motor vehicle, also referred to simply as a vehicle, which is preferably a car, especially a passenger car. This means that the motor vehicle, in its fully manufactured state, has the wheel brake. The wheel brake is also simply referred to as a brake or braking device.The wheel brake has a first brake element, which has a first friction surface. The first brake element is, for example, a first brake disc, which has the first friction surface. The wheel brake also has a second brake disc, which is a second brake element of the wheel brake. The brake disc (second brake element) is rotatable about an axis of rotation on a wheel carrier and is rotatable about the axis of rotation relative to the first brake element and, in particular, also relative to the wheel carrier.It is conceivable that, in the fully manufactured state of the motor vehicle, a vehicle wheel of the motor vehicle is rotatably mounted on the wheel carrier about the axis of rotation, also referred to as the wheel axis, relative to the wheel carrier, for example via a wheel hub that is non-rotatably connected to the vehicle wheel, which is rotatably mounted on the wheel carrier about the axis of rotation relative to the wheel carrier, for example via a wheel bearing designed, for example as a rolling bearing. For example, the brake disc, which is specifically designed separately from the wheel hub, is connected to the wheel hub in a rotationally fixed manner and thus to the vehicle wheel in a rotationally fixed manner, whereby the brake disc is rotatable about the axis of rotation relative to the wheel carrier and relative to the first brake element. In particular, the brake disc (second brake element) can be connected to the wheel hub in a rotationally fixed manner, at least indirectly. The brake disc is displaceable along the axis of rotation and thus in the axial direction of the wheel brake relative to the first brake element, and in particular also relative to the wheel carrier and especially relative to the wheel hub; it is therefore translationally movable. The axial direction of the wheel brake coincides with the axis of rotation. When the axial direction is mentioned before and after, unless otherwise specified, this refers to the axial direction of the wheel brake, whose radial direction is perpendicular to the axial direction and thus perpendicular to the axis of rotation. When the radial direction is mentioned before and after, unless otherwise specified, this refers to the radial direction of the wheel brake. The brake disc has a second friction surface facing the first friction surface along the axis of rotation. The brake disc also has a third friction surface facing away from both the second and first friction surfaces along the axis of rotation. For example, the second brake element is a pad carrier disc, which may have a support element that carries two brake pads of the pad carrier disc. In this case, for example, one of the brake pads forms the second friction surface, and a second of the brake pads forms the third friction surface. In particular, the brake pads are positioned axially from a side of the support element facing away from the first surface. The third friction surface faces away from the first and second friction surfaces along the axis of rotation, and faces a fourth friction surface of a third brake element of the wheel brake along the axis of rotation. The third brake element can be moved towards the second brake element and the first friction surface, particularly translationally, by actuating the wheel brake along the axis of rotation, in particular by hydraulic means. This allows the second friction surface to be brought into contact with the first friction surface, in particular direct and / or frictional contact, and the fourth friction surface to be brought into contact with the third friction surface, in particular direct and / or frictional contact, to brake the vehicle wheel and thus the motor vehicle.In other words, by actuating the wheel brake, particularly hydraulically, the third brake element is moved translationally along the axis of rotation towards the second brake element and the first friction surface, so that the fourth friction surface is brought into contact with the third friction surface, and the third brake element and the second brake element are moved translationally along the axis of rotation towards the first friction surface, thereby bringing the second friction surface into contact with the first friction surface. Put another way, the fourth friction surface is pressed against the third friction surface and the second friction surface against the first friction surface, and the second brake element, and in particular the second friction surface and the third friction surface, are compressed between the first friction surface and the fourth friction surface along the axis of rotation.This allows the vehicle wheel to be braked or slowed down, and thus at least its rotation around the axis of rotation and relative to the wheel carrier can be slowed down, thereby allowing the vehicle to be braked or slowed down. The second brake element has a friction surface area, also referred to as the brake pad contact area, since the second and third friction surfaces are located within this area. Furthermore, the second brake element has a coupling area extending radially inwards, and thus towards the axis of rotation, from the friction surface area. This coupling area allows the second brake element to be, or at least indirectly, rotationally fixed to the vehicle wheel, particularly the wheel hub. The second brake element also has a structure arranged radially between the friction surface area and the coupling area. This structure is flexible and thus elastically deformable in the axial direction of the wheel brake and is elastically deformed when the wheel brake is actuated, particularly when the brake is applied.During braking, i.e., during application of the wheel brake, the structure undergoes axial, and in particular purely elastic, deformation. This creates a continuous relationship between the actuating force applied to the wheel brake and the actuating path by which the second brake element is moved translationally along the axis of rotation. The elastic deformation of the structure returns to its original state after the actuation ceases; in other words, the elastically deformed structure springs back after the wheel brake is applied, particularly independently, thus eliminating the need for a separate return spring. This allows for a particularly space-saving, lightweight, and cost-effective design of the wheel brake. Furthermore, it enables particularly advantageous metering of the wheel brake, which is also simply referred to as a brake.The background of the invention is, in particular, that as soon as the third brake element is axially pushed onto the second brake element at the start of a braking process, and thus the fourth friction surface is axially pushed onto the third friction surface, a friction process begins, especially between the third brake element and the second brake element. Consequently, a torque is transmitted between the second brake element and the wheel hub, and thus, for example, to an output shaft provided for driving the wheel hub and the vehicle wheel, which can oppose the axial displacement of the second brake element. To increase the braking torque, however, the second brake element must be moved further axially, in particular to bring the second friction surface into contact with the first friction surface.Since static friction effects can occur, poor modulation can result if no countermeasure is taken, particularly in the range of low braking torques. This can now be avoided by the invention, eliminating the need for a separate return spring. This allows for particularly good modulation of the wheel brake in a space-saving, cost-effective, and weight-efficient manner. In particular, the wheel brake is a preferably dustproof braking device arranged in an interior space of the vehicle wheel, also referred to as the wheel interior, which, for example, has the first brake element as the first brake disc, the second brake element as the second brake disc and the third brake element, which, for example, is designed as a pressure plate and / or as a third brake disc. The coupling area is a force transmission area through which the aforementioned torque transmission takes place. The axial direction coincides with an actuation direction in which, when the wheel brake is applied, the third brake element and, in particular, the second brake element are moved towards the first wheel surface. The structure is flexible along or in the actuation direction, and thus elastically deformable, which allows for particularly precise modulation. Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment and from the drawings. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention. The drawing shows in: Fig. 1 a partial schematic sectional view of a wheel brake of a motor vehicle; and Fig. 2 a partial schematic and perspective rear view of the wheel brake. In the figures, identical or functionally equivalent elements are provided with the same reference symbols. Fig. 1 shows a partial schematic sectional view of a wheel brake 10 of a motor vehicle, designed as a friction brake and, in this case, as a disc brake. The wheel brake 10 is also simply referred to as a brake or braking device. The wheel brake 10 has a first brake element 12, which has a first friction surface 14. The wheel brake 10 also has a brake disc 20, which is rotatable about an axis of rotation 16, also referred to as the wheel axis, relative to a wheel carrier 18 and is, in this case, mounted on a wheel carrier 18. This disc is a second brake element of the wheel brake 10. The wheel carrier 18 has a shock absorber mount 22, to which a shock absorber can be attached or is attached. The wheel carrier 18 can be supported, or is supported, against a body of the motor vehicle via the shock absorber.The brake disc 20 (second brake element) is a pad carrier disc which has a carrier element 23 and brake pads supported by the carrier element 23, namely a first brake pad 24 and a second brake pad 26. The brake pad 24 forms a second friction surface 28 facing the first friction surface 14 along the axis of rotation 16 and thus in the axial direction of the wheel brake 10. The axial direction of the wheel brake 10 coincides with the axis of rotation 16 and is illustrated by a double arrow 30. The brake pad 26 forms a third friction surface 32, which points away from the friction surfaces 14 and 28 along the axis of rotation 16, and is thus facing away from them. The wheel brake 10 has a third brake element 34, which has a fourth friction surface 36. The friction surface 32 faces the friction surface 36 along the axis of rotation 16, wherein the friction surface 36 faces the friction surface 14 along the axis of rotation 16. The brake disc 20 is displaceable along the axis of rotation 16 relative to the first brake element 12 and relative to the wheel carrier 18, and thus transiently movable. The third brake element 34 can be moved towards the brake disc 20 and the friction surface 14 along the axis of rotation 16 by actuating the wheel brake 10, in particular hydraulically, so that by actuating the wheel brake 10, the brake element 34, in particular the friction surface 36, can be pressed along the axis of rotation 16 against the brake disc 20, in particular the friction surface 32, and the brake disc 20, in particular the friction surface 28, can be pressed along the axis of rotation 16 against the brake element 12, in particular the friction surface 14. This allows the friction surface 28 to be brought into contact with the friction surface 14 and the friction surface 36 into contact with the friction surface 32, thereby braking a vehicle wheel 38 of the motor vehicle and the motor vehicle itself. The system includes a wheel hub 40, also referred to simply as a hub, which is rotatably mounted on the wheel carrier 18 about the axis of rotation 16 relative to the wheel carrier 18 via a wheel bearing 42 designed as a rolling bearing. The wheel hub 40 has a flange 44, also referred to as an output flange, to which the vehicle wheel 38 is non-rotatably connected. The vehicle wheel 38 has a wheel disc 46, also referred to as a wheel bowl, a rim 48, a hump 50, and a rim flange 52. In particular, the wheel disc 46, and thus the vehicle wheel 38, is bolted to the flange 44 and thereby non-rotatably connected to the flange 44 and the wheel hub 40. The brake element 34 is designed, for example, as a pressure plate.It can be seen that the brake element 34 and the brake disc 20 are displaceable along the axis of rotation 16 relative to the wheel carrier 18 and relative to the brake element 12, wherein the brake element 12 is fixed to the wheel carrier 18 in a rotationally fixed manner and, in particular, also immovably attached to the wheel carrier 18 along the axis of rotation 16. The brake disc 20 is connected to the vehicle wheel 38 in a rotationally fixed manner, so that by applying the wheel brake 10 the vehicle wheel 38 can be braked, and thus its rotations about the axis of rotation 16 relative to the wheel carrier 18 can at least be slowed down. The wheel hub 40 has a centering seat 54 by means of which the wheel disc 46 and thus the vehicle wheel 38 are positioned, in particular centered, relative to the wheel hub 40. A drive shaft 56 is also provided, comprising a first shaft section 58, a second shaft section 60, and a joint 62. The shaft sections 58 and 60 are articulated together by means of the joint 62. The wheel hub 40 is rotationally fixed to the shaft section 60 by means of a central screw 64. The drive shaft 56 can be driven by a motor of the vehicle, allowing the shaft section 60 to rotate about the axis of rotation 16 relative to the wheel carrier 18. This enables the vehicle wheel 38 to be driven and thus rotated about the axis of rotation 16 relative to the wheel carrier 18, so that the axis of rotation 16 is also referred to as the wheel axis of rotation. A cover cap is designated 66. A drive shaft boot is designated 68. It can be seen that the friction surface 14 is a counter-running surface for the friction surface 28. A drive element 70, separate from the vehicle wheel 38 and the wheel hub 40, is provided and is rotationally fixed to both. The brake disc 20, also separate from the drive element 70, is rotationally fixed to the drive element 70 and is displaceable along the axis of rotation 16 relative to the drive element 70. For this purpose, the drive element 70 has a drive tooth 72 by means of which the brake disc 20 is rotationally fixed to the drive element 70. A seal 74, in this case designed as a radial shaft seal, is also provided. The hub of the brake disc 20, which in this case is designed as a pad carrier disc, is designated 76. The wheel brake 10 has a piston 78, in this case designed as a stepped piston and also referred to as an actuating piston or brake piston, and a pressure chamber 80 delimited by the piston 78, into which hydraulic fluid can be introduced. This allows the piston 78 to be actuated, in particular directly, by the hydraulic fluid, thereby enabling the wheel brake 10 to be actuated, in particular hydraulically. By acting upon the piston 78 with the hydraulic fluid, the piston 78 is transiently movable, and thus displaceable, along the axis of rotation 16 relative to the wheel carrier 18 and relative to the brake element 12 in the direction of the brake element 12.This displacement of the piston 78 is transmitted via a transmission element 82 to the brake element 34, which is thereby displaceable along the axis of rotation 16 relative to the brake element 12 and relative to the wheel carrier 18 such that the brake element 34 can be transiently moved onto the brake disc 20 and the friction surface 14, and consequently the friction surface 28 can be brought into contact with the friction surface 14 and the friction surface 36 into contact with the friction surface 32. This allows the vehicle wheel 38 to be braked. A return groove, designed in particular for returning the brake disc 20 and thus the brake element 34 and the piston 78, is designated 84. The wheel brake 10 now also has a housing 86. The housing 86 has the brake element 12 as a first housing part 88 and a second housing part 90, which is formed separately from the housing part 88 and is connected to the housing part 88, in particular directly, especially by screws. The housing 86 also has a receiving area 92, also referred to as a receiving space, in which the brake disc 20 and the brake element 34 are each at least partially received. In this case, the friction surfaces 14, 28, 36 and 32 are each at least partially, in particular at least predominantly and thus at least more than half or completely, received in the receiving space. The housing 86 seals the receiving space and the wheel brake 10 from their surroundings, thereby preventing excessive corrosion of the brake elements, especially on the friction surfaces 14, 28, 32 and 36. The housing 86 also has through-openings 94 and 96 (Fig. 2). The through-openings 94 are arranged on a first side of the housing 86, the first side of which is visible in Fig. 2. The through-openings 96 are arranged on a second side of the housing 86, radially opposite the first side, and are therefore not visible in Fig. 2. Each through-opening 94, 96, also simply referred to as an opening, opens at one end into the receiving space and at the other end into a surrounding area 98 of the housing 86, particularly when considering only the housing 86. In the embodiment shown in the figures, each opening is continuous in the radial direction, particularly when considering only the respective opening. From Fig. 1 and Fig. 2 it is particularly evident that each opening is assigned a respective closing element 100, which can be moved relative to the housing 86 by heating the housing 86 and thus by thermal activation from a closed position S (Fig. 1) which closes the respective assigned through-opening 94, 96 to an open position O (Fig. 2) which at least partially releases the respective assigned through-opening 94, 96. Preferably, the vehicle wheel 38 is a vehicle wheel of a vehicle axle configured as a front axle of the motor vehicle. Since the drive shaft 56 has the joint 62, the drive shaft 56 is designed as a cardan shaft. Since the vehicle wheel 38 can be driven via the drive shaft 56, the vehicle wheel 38 is a driven vehicle wheel. The wheel carrier 18 is guided by axle links (not shown). The wheel hub 40 is rotatably mounted on the wheel carrier 18 by means of the wheel bearing 42, which in this case has two angular contact ball bearings in an O-arrangement. In particular, the wheel disc, and thus the vehicle wheel 38, is bolted to the flange 44 of the wheel hub 40 by means of wheel bolts. The wheel brake 10, also referred to as the braking device, is designed as an inverted disc brake and is arranged in a wheel chamber 102 of the vehicle wheel 38. For example, the wheel brake 10 has an outer geometry that is at least partially cylindrical. The drive element 70 is clamped between the flange 44 and the wheel disc by friction. The drive element 70, which is top-shaped and preferably designed as a milled metallic component, has the drive teeth 72 on its radial outer surface. The brake disc 20, which has brake pads 24, 26 on both sides and is designed, for example, as a metallic pad carrier disc, meshes with the drive teeth 72 with its toothed hub 76. For example, the brake disc 20 has a plane-parallel contact surface on its radial outer surface.Since the hub 76 is toothed, it has a toothed section located on an inner radius of the hub 76, which serves to transmit force to the driver 70. The axially flexible return groove 84 is formed in the brake disc 20, particularly with force flow between a brake pad contact and a force transmission point. Preferably, the housing part 88 and / or the housing part 90 is made of an aluminum alloy. The housing 86, in particular the housing part 90, is connected, in particular directly, to the wheel carrier 18, in particular by bolting. The housing 86 serves as the base component of the braking device. This base component absorbs the axial forces acting on the counter-running surface (friction surface 14) during braking and transfers them to the wheel carrier 18. The housing 86, in particular the housing part 90, has internal locking teeth 104 by means of which the brake element 34 is rotationally fixed to the housing 86, in particular via housing part 90. A guide element 106, for example designed as a guide plate, is provided on the housing 86, in particular on the housing part 90, along which the brake element 34 can be displaceably guided along the axis of rotation 16.The present axially movable brake element 34, designed as a pressure plate, is inserted into the housing 86. The brake element 34 has a toothed section on its radial outer circumference that corresponds to the locking toothing 104, by means of which it is rotationally fixed to the housing 86. This fixes the brake element 34 relative to the housing 86 in the circumferential direction, which runs around the axis of rotation 16 and thus around the axial direction. Housing part 88 is a cover forming the counter-running surface, which is screwed to housing part 90, for example. This seals the receiving chamber and thus the brake assembly, particularly from the outside. The cover carries the seal 74 on its inner diameter, the sealing lip of which runs against a cylindrical outer surface of the driver 70. The piston 78, for example, is part of an actuator, also known as an actuator, actuating actuator, or actuating actuator, arranged coaxially to the axis of rotation 16. This actuator actuates the brake element 34, designed as a brake disc, in the region of its inner diameter. For this purpose, the housing 86, for example, forms a hydraulic cylinder arranged coaxially to the wheel's axis of rotation (axis of rotation 16). The piston 78, designed, for example, as a stepped piston, is arranged within the hydraulic cylinder. The pressure chamber 80 is formed between the housing 86 and the stepped piston. This pressure chamber can be hydraulically actuated by introducing hydraulic fluid into the pressure chamber 80. The actuator is thus designed as a hydraulic ring-shaped stepped piston with a corresponding cylinder and is arranged coaxially to the brake elements 12 and 34, the brake disc 20, and the vehicle wheel 38.Because the brake element 34 is only subjected to pressure in the region of its inner diameter, it can be supported in the region of its outer diameter by the axially flexible brake disc 20 against the counter-running surface. To brake the vehicle wheel 38, pressurized hydraulic fluid is introduced into the pressure chamber 80. This causes the piston 78 to move axially away from the wheel carrier 18 and towards the friction surface 14. Via the transmission element 82, which acts as a thermal break, the piston 78, by applying pressure in the region of its inner diameter, first moves the brake element 34, designed as a pressure plate, towards the brake disc 20 and subsequently the disc against the counter-running surface. The brake element 34, which is fixed in the circumferential direction, and the counter-running surface (friction surface 14), which is also fixed in the circumferential direction, brake the brake disc 20 and thus the vehicle wheel 38.During braking, the heat is primarily released in the opposing friction surfaces. The openings, and thus the receiving space and the wheel brake 10 designed as a friction brake, are closed to the outside by the closing elements 100, which are designed, for example, as leaf spring elements. For example, each closing element 100 is inserted into its corresponding opening. This prevents excessive corrosion in the receiving space. The housing 86, preferably made of aluminum, thus has the openings as air inlet and air outlet openings. For example, the through-openings 94 are or function as inlet openings through which air can be introduced into the receiving chamber. For example, the through-openings 96 function as outlet openings through which the air can be discharged from the receiving chamber. The outlet openings are also referred to as discharge openings or vent openings. Thus, the inlet openings, which are also referred to as entry openings, are the aforementioned air inlet openings, and the outlet openings are the aforementioned air outlet openings. In a new condition, the wheel brake 10 has sealing elements 100, designed, for example, as steel leaf spring elements, pressed into the openings in such a way that the sealing elements 100 close the openings watertight. The leaf spring elements are under preload.Since the preferably electrically powered vehicle normally decelerates exclusively through recuperation, the wheel brake 10, designed as a friction brake, is not normally actuated. Light braking, for example for testing purposes, can be performed without thermally activating and thus opening the sealing elements 100, which function as or form a seal. The resulting heat is dissipated to the environment on an outer surface of the housing 86, in particular the cover. Normally, the brake remains sealed throughout the vehicle's entire service life, meaning the sealing elements 100 remain in the closed position S. For example, in an emergency, if the recuperation system fails, the wheel brake 10 is actuated and becomes hot during heavy braking.In this case, the aluminum housing 86 of the wheel brake 10 heats up and expands more than the steel leaf spring elements pressed into the openings. This releases the leaf spring elements to move into their respective open position O, thus opening the openings. Therefore, during heavy braking, especially emergency braking, the brake is cooled internally, i.e., within the receiving chamber, by air, as air can flow into the receiving chamber through the inlet openings. Since humid air may enter the receiving chamber and pass through the brakes, the openings remain open after a single activation, i.e., after the locking elements 100 have been opened once. The emergency braking event is stored, for example, in a control unit. The brake can then be checked during the next vehicle maintenance.If it is in good working order, during maintenance only the openings are closed, for example by moving the locking elements 100, in particular again, into their closed positions S relative to the housing 86. It can be seen that the brake disc 20 has a friction surface area B1 in which the brake pads 24 and 26, and thus the friction surfaces 28 and 32, are arranged. The brake disc 20 also has a coupling area B2 extending radially inwards towards the wheel brake 10, onto the friction surface area B1. In this coupling area, for example, the hub 76 and, in particular, the aforementioned toothing of the brake disc 20 are arranged, which interacts with the drive teeth 72, thereby connecting the brake disc 20 to the drive hub 70 in a rotationally fixed manner. Thus, the brake disc 20 is connected to the drive hub 70 in a rotationally fixed manner via the coupling area B2, so that the brake disc 20 is indirectly connected to the vehicle wheel 38 and the wheel hub 40 in a rotationally fixed manner via the coupling area B2. The brake disc 20 also has a structure ST, which is arranged radially along the wheel brake between the friction surface area B1 and the coupling area B2. In the axial direction of the wheel brake 10, and thus along the axis of rotation 16, the structure ST is designed to be flexible and therefore elastically deformable. The coupling area B2, and thus the toothing arranged therein, serves to transmit force from the brake disc 20 to the drive element 70. The structure ST is arranged in a force flow between the friction surface area B1 and the aforementioned force transmission point, i.e., the coupling area B2. In the embodiment shown in the figures, the structure ST is formed by the axially flexible restoring groove 84. In an alternative embodiment, for example, the housing part 90 is designed as a ring anchor comprising an inner ring, an outer ring, and several, in particular exactly four, spokes by which the inner ring is connected to the outer ring. The ring anchor is, for example, screwed to the wheel carrier 18. The ring anchor can function as a basic component of the wheel brake 10, also referred to as a braking device. The ring anchor can absorb the axial forces acting on the counter-running surface during braking and transfer them to the wheel carrier 18. The outer ring of the ring anchor has, for example, the locking teeth 104 on a radial inner surface.The axially movable brake element 34 can be inserted into the ring anchor, in particular as an axially movable pressure plate, which has on its radial outer circumference four corresponding teeth to the ring anchor or its fixing toothing, by means of which the pressure plate can be connected to the ring anchor in a rotationally fixed manner. The wheel brake 10 is closed by the cover forming the counter-running surface, which is, for example, screwed to the ring anchor. On its inner circumference, the cover carries the radial shaft seal ring, whose sealing lip runs sealingly on the cylindrical outer surface of the driver 70. The actuator is arranged coaxially with the axis of rotation 16 and actuates the third brake element 34 in the region of its inner diameter. For example, the inner ring of the ring anchor supports the hydraulic cylinder, which is arranged coaxially with the axis of rotation 16 and may include a stepped piston. A pressure chamber 80, which can be hydraulically actuated, can be formed between the ring anchor and the stepped piston. The actuator is thus designed as a hydraulic ring-shaped stepped piston with a corresponding cylinder and is arranged coaxially with the brake components and the vehicle wheel 38. Because the brake element 34 is actuated exclusively in the region of its inner diameter, it can be supported in the region of its outer diameter by the axially flexible brake disc 20 against the counter-running surface. To apply the brakes, hydraulic fluid is introduced into the pressure chamber 80. This causes the piston 78 to move axially away from the wheel carrier 18 and towards the friction surface 14. The piston 78, via the transmission element 82, moves the brake element 34, by applying pressure in the area of ​​its inner diameter, initially towards the brake disc 20. Since the brake disc 20 rotates in contrast to the stationary pressure plate, friction now occurs between the brake disc 20 and the brake element 34 (pressure plate). The brake disc 20 transmits a torque to the drive teeth 72 and thus to the drive pin 70. The brake disc 20 is axially fixed in the teeth of the drive pin 70 due to the static friction that occurs there.If the brake disc 20 is now moved further by means of the piston 78 until it contacts the opposing running surface (friction surface 14), the hub 76 of the brake disc 20 remains axially stationary relative to the drive 70, so that the axial displacement of the brake disc 20 only occurs in a radially outer area adjoining the structure ST in a radial direction, which is, for example, the friction surface area B1 or includes the friction surface area B1, particularly because the structure ST, in this case the restoring groove 84, generates only very small axial forces. The restoring groove 84 is deformed axially by approximately 0.05 mm, for example.When, at the end of the braking process, a force acting axially on the brake elements by means of the piston 78 is reduced, particularly to zero, the return groove 84, also referred to simply as a bead, can deform back automatically and spring back, thereby lifting the brake disc 20 from the counter-running surface. The groove thus acts as a return element. Since there is no longer any axial force acting between the pressure plate and the brake disc 20, there is also no longer any torque acting between the teeth of the brake disc 20 and the drive teeth 72 of the drive pin 70. The hub 76 of the brake disc 20 is therefore axially displaced relative to the drive pin 70. Therefore, if wear has occurred, the hub 76 can assume a new axial position after the braking process. The circumferentially fixed pressure plate and the equally fixed counter-friction surface brake the brake disc 20 and thus the vehicle wheel 38. During braking, the heat is primarily released in the counter-friction surfaces. The heat is dissipated to the environment on the outside of the cover. Since the pressure plate extends through the ring anchor in four openings, it can also effectively dissipate the braking heat to the environment. In a conventional disc brake, the cylindrical brake disc is braked from the outside. Its circular axial side surfaces serve, among other things, to dissipate heat to the environment. However, they cannot dissipate heat completely because they are partially covered on the outside by the brake caliper. In contrast, the wheel brake 10 is an inverted disc brake, which is braked from the inside. Therefore, the entire outer surface is available for heat dissipation. Preferably, the vehicle wheel 38 is a vehicle wheel of a front axle of the motor vehicle. QUOTES INCLUDED IN THE DESCRIPTION This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature DE 2 018 557 A1

[0002]

Claims

Wheel brake (10) for a motor vehicle, comprising a first brake element (12) having a first friction surface (14), and a brake disc (20) as a second brake element, rotatable about an axis of rotation (16) on a wheel carrier (18) or mounted and rotatable about the axis of rotation (16) relative to the first brake element (12), which is displaceable along the axis of rotation (16) relative to the first brake element (12) and has a second friction surface (28) facing the first friction surface (14) along the axis of rotation (16) and a third friction surface (32) facing away from the first friction surface (14) and the second friction surface (28) along the axis of rotation (16), which faces away from the first friction surface (16) and the second friction surface (28) along the axis of rotation (16) and faces a fourth friction surface (36) of a third brake element (64) of the wheel brake (10),the third brake element (34) of which can be moved along the axis of rotation (16) towards the second brake element and the first friction surface (14) by actuating the wheel brake (10), whereby the second friction surface (28) can be brought into contact with the first friction surface (14) and the fourth friction surface (36) can be brought into contact with the third friction surface (32) for braking the motor vehicle, wherein the second brake element has a friction surface area (B1) in which the second friction surface (28) and third friction surface (32) are arranged, a coupling area (B2) via which the second brake element is or can be coupled at least indirectly rotationally fixed to a vehicle wheel (38) of the motor vehicle which is or is to be rotatably mounted on the wheel carrier (18) about the axis of rotation (16) relative to the wheel carrier (18), and a radially arranged between the friction surface area (B1) and the coupling area (B2) of the wheel brake (10).The wheel brake (10) has a structure (ST) that is flexible in the axial direction. Wheel brake (10) according to claim 1, characterized in that the structure (ST) has at least or exactly one groove (84).

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