Friction disc brake system for a motor vehicle and electric axle drive system for a motor vehicle

Abstract

The invention relates to a friction disc brake device (14) for a motor vehicle, comprising at least one first brake disc element (16) having at least one first friction surface (18), at least one second brake disc element (20) having at least one second friction surface (22), a piston (34) that can be actuated with hydraulic fluid and thereby hydraulically actuated, and a transmission element (54) formed separately from the piston (34), wherein the transmission element (54) and, via the transmission element (54), the first brake disc element (16) can be actuated by hydraulic actuation of the piston (34), thereby bringing the friction surfaces (28, 22) into frictional contact with each other to effect braking, and wherein the transmission element (54) has a first groove (78). The piston (34) has a second groove (80).In the grooves (78, 80) an intermediate element (82) is arranged, which is formed separately from the transmission element (54) and separately from the piston (34), via which the transmission element (54) and the piston (34) are connected to each other.

Description

[0001] The invention relates to a friction disc brake device for a motor vehicle according to the preamble of claim 1. Furthermore, the invention relates to an electric axle drive device for a motor vehicle.

[0002] DE 10 2019 100 738 B3 discloses an electric axle drive unit for a motor vehicle as known, comprising an electric motor, wherein a stator of the electric motor is fixedly mounted in a housing and a rotor of the electric motor, rotatably mounted relative to the stator, is rotaryally coupled or rotatably coupled to a wheel hub.

[0003] The object of the present invention is to create a friction disc brake device for a motor vehicle and an electric axle drive device for a motor vehicle, so that a particularly advantageous operation of the friction disc brake device can be realized.

[0004] This problem is solved by a friction disc brake device with the features of claim 1 and by an electric axle drive device with the features of claim 10. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims.

[0005] A first aspect of the invention relates to a friction disc brake device, also simply referred to as a disc brake device, friction brake device, or brake device, for a motor vehicle, also simply referred to as a vehicle. This means that the motor vehicle, preferably designed as a motor vehicle, in particular as a passenger car, has the friction disc brake device in its fully manufactured state. For example, the motor vehicle, in its fully manufactured state, has at least one vehicle wheel, also simply referred to as a wheel. The vehicle wheel is a ground contact element by means of which the motor vehicle can be supported or is supported downwards against a ground in the vertical direction of the vehicle.When the motor vehicle is driven along the ground while supported downwards by the ground contact element in the vehicle's vertical direction, the ground contact element rolls along the ground, particularly directly. The motor vehicle mentioned above is thus also disclosed within the scope of the present disclosure and may therefore be part of the invention. The vehicle wheel is rotatable, for example, about a wheel axis relative to a housing of the motor vehicle, particularly the friction disc brake assembly, so that the vehicle rotates about the wheel axis relative to the housing, particularly when it rolls along the ground, especially directly. For example, the friction disc brake assembly can be used to brake, i.e., slow down, the vehicle wheel with respect to rotations about the wheel axis and relative to the housing, thereby, for example, braking the motor vehicle as a whole.The friction disc brake system is or constitutes a friction brake by means of which, for example, the vehicle wheel can be braked by friction. In particular, the friction disc brake system is or constitutes a service brake of the motor vehicle.

[0006] The friction disc brake assembly comprises at least one first brake disc element, which has at least one first friction surface. The friction disc brake assembly also comprises at least one second brake disc element, which has at least one second friction surface. For example, it is provided that the second brake disc element, and thus the second friction surface, is rotatable about an axis of rotation relative to the housing. For example, the second brake disc element, and thus the second friction surface, is rotatable with the vehicle wheel and therefore rotatable about the axis of rotation relative to the housing.In particular, it is conceivable that the second brake disc element, and thus the second friction surface, is connected or connectable to the vehicle wheel in a torque-transmitting manner, especially in a rotationally fixed manner, and is therefore rotatable with the vehicle wheel when it rotates around the wheel axis relative to the housing, and thus rotatable around the axis of rotation relative to the housing.

[0007] For example, the first brake disc element, and thus the first friction surface, is fixed to the housing and therefore cannot rotate relative to the housing about the axis of rotation. It is conceivable that the friction surfaces face each other axially, that is, in the axial direction of the friction disc brake assembly, and are thus opposite each other. The axial direction of the friction disc brake assembly, also simply referred to as the brake assembly, whose radial direction is perpendicular to the axial direction of the brake assembly and thus perpendicular to the axis of rotation, coincides with the axis of rotation and therefore runs along the axis of rotation.When the axial direction is mentioned before and below, unless otherwise specified, this refers to the axial direction of the braking device (friction disc brake device), whose circumferential direction runs around the axial direction and thus around the axis of rotation, and lies in an imaginary plane that is perpendicular to the axial direction and thus perpendicular to the axis of rotation. When the radial direction is mentioned before and below, unless otherwise specified, this refers to the radial direction of the braking device (friction disc brake device). When the circumferential direction is mentioned before and below, unless otherwise specified, this refers to the circumferential direction of the braking device (friction disc brake device). Furthermore, the term "axial" refers to the axial direction. Accordingly, the term "radial" refers to the radial direction.In other words, the term "axial" refers to the axial direction, and the term "radial" refers to the radial direction. Put another way, the term "axial" refers to the axial direction and the term "radial" refers to the radial direction.

[0008] The friction disc brake assembly has a piston, which is also referred to as an actuating piston, and is designed separately from the brake disc elements, which are also simply called brake discs. Preferably, the piston is an annular piston, meaning it is ring-shaped at least in a partial section. The piston can be actuated with hydraulic fluid, particularly directly, and thus, in particular axially, hydraulically. For this purpose, the housing, for example, has a hydraulic channel through which the hydraulic fluid flows, and by means of which the hydraulic fluid flowing through the hydraulic channel can be introduced into an actuating chamber that is partially bounded by the piston and partially by the housing, particularly directly in each case. By introducing the hydraulic fluid into the actuating chamber, the piston can be actuated with the hydraulic fluid, particularly directly, and thus, in particular axially, in an actuating chamber.In particular, the actuation of the piston, especially axially, means that by applying hydraulic fluid to the piston, the piston can be moved, especially axially, relative to the housing.

[0009] The friction disc brake device has a transmission element that is separate from the piston and preferably also separate from the first brake disc element and, most preferably, also separate from the second brake disc element. The transmission element is also referred to as the actuating element. By means of the piston, the transmission element, and via the transmission element the first brake disc element, can be actuated by hydraulic actuation of the piston. This allows the friction surfaces to be brought into, in particular, direct, mutual frictional contact to effect braking, especially of the vehicle wheel. This mutual and preferably direct frictional contact between the friction surfaces generates the aforementioned friction, in particular between the friction surfaces, which allows, for example, the vehicle wheel to be braked, i.e., slowed down, especially relative to the housing.It is evident that the transmission element can be actuated by hydraulically actuating the piston and is thereby movable, particularly axially, relative to the housing. This movement of the transmission element relative to the housing, and preferably axially, allows the first brake disc element, and thus the first friction surface, to move, particularly axially, relative to the housing and especially in the direction of the second friction surface. This enables the friction surfaces to be brought into, in particular, direct, mutual frictional interaction, and thus into the aforementioned, in particular, direct, mutual frictional contact.Since, for example, the second brake disc element, and thus the second friction surface, can rotate with the vehicle wheel and is therefore rotatable around its axis of rotation relative to the housing, as well as relative to the first brake disc element and the first friction surface, friction is generated between the friction surfaces when the surfaces are in frictional contact and the second brake disc element rotates around its axis of rotation relative to the housing and the first friction surface. This friction allows the second brake disc element, and, for example, the vehicle via the second brake disc element, to be braked relative to the housing. Thus, the aforementioned braking, also referred to as deceleration, is to be understood as the braking of the second brake disc element relative to the housing, particularly with regard to the rotation of the second brake disc element around its axis of rotation relative to the housing.

[0010] To ensure particularly advantageous operation of the braking system, especially over extended periods of operation, so that, for example, the braking system can still effectively decelerate the vehicle wheel even after prolonged use, the invention provides that the transmission element has a first groove and the piston a second groove, wherein an intermediate element, separate from the transmission element and the piston, is arranged in the grooves, connecting the transmission element and the piston. In particular, the grooves are arranged in mutual overlap. For example, the intermediate element is partially located in the first groove and partially in the second groove. The intermediate element provides thermal separation between the transmission element and the piston.In other words, the intermediate element allows for advantageous thermal decoupling of the transmission element from the piston and vice versa, thus preventing excessive and undesirable heat transfer from the transmission element to the piston and subsequently from the piston to the hydraulic fluid (also known as brake fluid). Consequently, excessive temperature of the piston (also known as the brake piston) and the hydraulic fluid can be avoided, ensuring optimal functionality of the friction disc brake system, particularly with regard to braking performance, even over extended periods of operation and after very frequent braking.

[0011] By applying pressure to the piston, particularly directly, an actuating force can be generated, resulting from the pressure of the hydraulic fluid and acting axially on the piston. This actuating force, acting axially on the piston, makes the piston actuated and thus movable, particularly axially, relative to the housing. This actuating force, also simply referred to as force, can be transmitted, particularly exclusively, via the intermediate element from the piston to the transmission element, thereby making the transmission element actuated and thus movable, particularly axially, relative to the housing. This allows the friction surfaces to be brought into mutual, particularly direct, frictional contact, and in particular to be compressed, thus enabling braking, particularly of the vehicle wheel.The intermediate element is arranged between the piston and the transmission element, and thus between the piston and the first brake disc element, which makes the previously described thermal decoupling advantageously possible.

[0012] In particular, it is conceivable that the piston, the transmission element and the first brake disc element are movable, especially axially, relative to the housing, and in particular displaceable, i.e., slidable, wherein by hydraulic actuation of the piston the piston and, via the intermediate element, the transmission element and, via the transmission element, the first brake disc element are displaceable, especially axially, relative to the housing, in order to bring the friction surfaces into mutual frictional contact and thus effect braking.

[0013] Preferably, the friction disc brake system is a dry-running brake. This means that the friction surfaces are not immersed in a fluid such as oil, but run dry.

[0014] The piston, for example, is part of a hydraulic actuation device by means of which the first brake disc element, and thus the friction disc brake assembly, can be actuated to effect braking. The hydraulic actuation device can also include the hydraulic channel and, for example, the working chamber. Furthermore, any misalignment, such as that caused by tolerances, particularly between the piston and transmission element and / or between the piston and the first brake disc element, can be compensated for by means of the intermediate element, thereby enabling particularly efficient operation of the brake assembly.

[0015] Preferably, the friction disc brake system is integrated into an axle component of the motor vehicle. In other words, the motor vehicle, in its fully manufactured state, has the axle component into which the friction disc brake system is integrated. For example, the axle component could be an electric axle drive unit, a differential, or a chassis component.

[0016] One aspect of the invention is that, if no countermeasures are taken, a friction disc brake system, if designed as a dry-running brake system, can become very hot compared to wet-running brake systems, particularly during braking. If, for example, a friction disc brake system is integrated into the axle assembly, then, during driving and braking by means of the friction disc brake system, a sufficient amount of airflow may not reach the friction disc brake system to cool it. To prevent the resulting excessive heating of the hydraulic fluid, an intermediate element is provided by which the piston is advantageously thermally decoupled from the transmission element and thus from the friction surfaces, in which a large amount of heat can be generated during braking.

[0017] In order to thermally decouple the piston particularly advantageously from the transmission element and thus from the friction surfaces, one embodiment of the invention provides that the transmission element, particularly on its inner circumference, has a projection extending axially from a base region of the transmission element, in the outer circumferential surface of which the first groove is formed. The outer circumferential surface faces radially outwards. The piston has an inner circumferential surface facing radially towards the outer circumferential surface and extending radially inwards, which surrounds the outer circumferential surface and the first groove circumferentially, in particular completely and thus over 360°. The second groove is formed in the inner circumferential surface.

[0018] Preferably, the respective groove is an annular groove that extends completely around the circumference and thus over 360°.

[0019] A further embodiment of the invention is characterized in that a chamfer on the inner circumferential surface of the piston, widening axially towards the base region, adjoins the second groove at an end of the piston axially facing the base region. This allows, for example, the intermediate element to be mounted on the piston, and in particular in the second groove of the piston, in a particularly simple and therefore time- and cost-effective manner, such that, especially in a method for manufacturing the friction disc brake device, the intermediate element is moved in the axial direction relative to the piston, particularly translationally, and especially in the axial direction, and slides along the chamfer. Since the chamfer tapers axially towards the second groove, the intermediate element is radially compressed as it slides along the chamfer.By further axial and relative movement of the intermediate element relative to the piston, particularly translationally, the intermediate element can be moved into overlap with the second groove. The intermediate element can then relax radially, at least or exclusively partially, causing it to engage, lock into, or snap into the second groove. Typically, the intermediate element sits firmly in the second groove and thus securely on the piston, thereby enabling a simple and advantageous operation of the braking device.

[0020] In order to achieve a particularly advantageous thermal decoupling and thus a particularly advantageous operation of the braking device, it is further provided in the invention that the intermediate element, especially when considered on its own, is elastically deformable, for example, in a rubber-elastic manner.

[0021] It proved particularly advantageous if the intermediate element was made of an elastomer and therefore elastically deformable due to its material properties and / or geometric design. This allows for particularly advantageous thermal decoupling and ensures particularly advantageous actuation of the transmission element, and thus of the first brake disc element, by actuating the piston, thereby guaranteeing particularly advantageous operation of the braking system.

[0022] To achieve a particularly advantageous operation of the friction disc brake device, a further embodiment of the invention provides that, through hydraulic actuation of the piston, the piston is movable axially relative to the transmission element and in the direction of the friction surfaces, particularly translationally and relative to the housing, under elastic deformation of the intermediate element. This allows an end face of the piston, which, for example, terminates axially at the end face, to move axially into direct contact with a corresponding support surface of the transmission element. In this way, the piston interacts directly with the transmission element via the end face and the support surface, enabling the actuating force to be transmitted particularly advantageously from the piston to the transmission element and thus to the first brake disc element. This allows for a particularly advantageous braking action using the brake device.

[0023] Preferably, the piston is made of a metallic material, and preferably the transmission element is also made of a metallic material. If the end face is in direct contact with or against the support surface, this creates direct metallic contact between the piston and the transmission element, allowing the transmission element, and via it the first brake disc element, to be actuated particularly advantageously by means of the piston.

[0024] Furthermore, in this embodiment of the invention, it is provided that in the unactuated state of the piston, i.e., when the piston is not pressurized with hydraulic fluid or when no force intended or designed to actuate the piston acts on the piston, the end face is completely separated from the support surface. This prevents excessive, undesirable heat transfer from the transmission element to the piston, thus providing particularly advantageous thermal decoupling.

[0025] Thus, the transmission element is only in contact with the piston when it is pressurized, i.e., only during braking when the friction disc brake system is used. As soon as the pressure is released, so that the piston is no longer actuated, the piston is moved away from the transmission element, particularly axially, thereby moving the end face away from the support surface.The piston and thus the end face are moved away from the transmission element and thus from the support surface, particularly axially, for example, by or in such a way that during the aforementioned pressure relief, i.e., when the actuation of the piston is stopped, a relaxation of the intermediate element, which has been elastically deformed as a result of the actuation of the piston, is permitted, so that, for example, through the relaxation of the elastically deformable intermediate element, the piston and thus the end face can be moved away from the transmission element and thus from the support surface, particularly axially.

[0026] In order to achieve a particularly advantageous thermal decoupling and thus a particularly advantageous operation of the friction disc brake device, it is provided in a further embodiment of the invention that in the unactuated state of the piston the piston is completely separated from the transmission element.

[0027] Another embodiment is characterized by the fact that the intermediate element is designed as an O-ring, which allows for a particularly advantageous thermal decoupling.

[0028] Finally, it has proven particularly advantageous if a shoulder surface, also simply referred to as a shoulder, is arranged in at least or exactly one of the grooves, especially in the first groove. This shoulder surface is arranged, for example, in or on the bottom of the at least or exactly one groove, or is formed by the bottom of the at least or exactly one groove. The intermediate element is supported on the shoulder surface, in particular directly, the shoulder surface being conical and thus extending along an imaginary cone that widens axially towards the friction surfaces.This ensures, for example, that when the intermediate element can elastically relax again, this elastic relaxation, also known as expansion, does not occur exclusively radially, but at least partially, and in particular also axially. This expansion action of the intermediate element causes the piston, and thus its end face, to be pushed axially away from the transmission element and the impact surface. This guarantees particularly efficient operation.

[0029] It has proven particularly advantageous if the inner diameter of the piston in an axial region of the intermediate element has a radial gap to the outer diameter of the transmission element. This allows for the consideration of the maximum possible radial offset due to tolerances, and particularly advantageous thermal decoupling can be achieved.

[0030] Preferably, the transmission element is rigidly connected to the first brake disc element. For example, the transmission element is rigidly connected to the first brake disc element by means of a press fit.

[0031] It has also proven particularly advantageous if the transmission element is connected to the first brake disc element via a cooling structure arranged on its rear side. The rear side of the first brake disc element, for example, faces the transmission element, particularly axially. The cooling structure has, for example, at least one cooling channel through which a coolant flows. Preferably, the coolant is a cooling fluid, which can be, for example, an oil. Furthermore, the cooling fluid can comprise at least, and in particular predominantly, water. The first brake disc element and, for example, also the transmission element can be advantageously cooled by means of the coolant in order to prevent excessive heating of the piston and thus of the hydraulic fluid.For example, the first brake disc element, and thus in particular the cooling structure, is movable, especially axially, relative to the housing and, for example, also relative to the second brake disc element, and in particular displaceable.

[0032] In particular, it is conceivable that the aforementioned rear side of the first brake disc element is turned away from the first friction surface and especially also from the second friction surface, particularly axially.

[0033] A second aspect of the invention relates to an electric axle drive device for a motor vehicle. For example, the electric axle drive device is or comprises the aforementioned axle component. At least one friction disc brake device according to the first aspect of the invention is integrated into the axle drive device. Advantages and advantageous embodiments of the first aspect of the invention are to be regarded as advantages and advantageous embodiments of the second aspect of the invention, and vice versa.

[0034] It is evident that the intermediate element and / or the transmission element is / are bifunctional. The intermediate element or the transmission element enables the aforementioned advantageous thermal decoupling of the piston, and thus the hydraulic fluid, from the friction surfaces, and therefore from a location where a very high amount of heat can be generated during braking by the friction disc brake system. Furthermore, the intermediate element or the transmission element, particularly simultaneously, facilitates an advantageous force transmission, transferring the aforementioned actuating force from the piston to the first brake disc element. The friction disc brake system is therefore a very efficient brake with a high thermal load capacity.

[0035] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing. 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.

[0036] The drawing shows in: Fig. 1. A schematic sectional view of an electric axle drive unit of a motor vehicle, wherein a friction disc brake unit is integrated into the electric axle drive unit; and Fig. 2. Partially a schematic longitudinal sectional view of the friction disc brake assembly; and Fig. 3. Partially shown is another schematic longitudinal section view of the friction disc brake device.

[0037] In the figures, identical or functionally equivalent elements are provided with the same reference symbols.

[0038] Fig. Figure 1 shows a partial schematic longitudinal sectional view of an electric axle drive unit 10 of a motor vehicle, which is also simply referred to as the vehicle and can be driven, in particular purely electrically, by means of the electric axle drive unit 10. For example, the electric axle drive unit 10, also referred to as the electric drive module, has a vehicle axle of the motor vehicle. For example, the motor vehicle has exactly two vehicle axles, namely the aforementioned vehicle axle as the first vehicle axle and a second vehicle axle. The vehicle axles are arranged consecutively in the longitudinal direction of the motor vehicle and thus one behind the other. Each vehicle axle has exactly two vehicle wheels. The respective vehicle wheels of each vehicle axle are arranged on opposite sides of the motor vehicle in the transverse direction of the motor vehicle.The vehicle wheels of the motor vehicle are ground contact elements of the motor vehicle. Since, for example, the electric axle drive unit 10 comprises the first vehicle axle, the axle drive unit 10 also comprises the vehicle wheels of the first vehicle axle. For example, the vehicle wheels of the first vehicle axle can be driven electrically by means of the axle drive unit 10, and thus the motor vehicle can be driven electrically.

[0039] The axle drive unit 10 comprises a housing 12 and at least one electric machine (not visible in the figures), which is at least partially arranged in the housing 12. The electric machine has a stator and a rotor, which can be driven by means of the stator and is thus rotatable about a machine axis relative to the stator. The electric machine can provide drive torques via the rotor for, in particular, purely electric, driving of the vehicle wheels of the first vehicle axle. Furthermore, it is conceivable that at least or exactly one of the vehicle wheels of the first vehicle axle can be driven, in particular purely electric, by means of the electric machine and thus by means of the axle drive unit 10. When the vehicle wheels are mentioned below, unless otherwise specified, this refers to the vehicle wheels of the first vehicle axle.When the vehicle wheel is mentioned below, unless otherwise specified, this refers to the vehicle wheel that can be driven by means of the axle drive unit 10, that is, by means of the electric machine of the axle drive unit 10. Thus, the vehicle wheel can be driven by the rotor and is therefore rotatable about a wheel axis relative to the housing 12.

[0040] For example, the axle drive unit 10 has a gearbox, which can be at least partially arranged in the housing 12. The preceding and following descriptions of the vehicle wheel can readily be applied to the vehicle wheels of the first vehicle axle and vice versa. For example, the vehicle wheel can be driven by the rotor and thus by the electric machine via the gearbox. As will be explained in more detail below, a braking device 14 is integrated into the axle drive unit 10, by means of which braking can be effected, i.e., carried out. During or through braking, the vehicle wheel can be braked with respect to a rotation about the wheel axis and relative to the housing 12, i.e., its rotation can be stopped.In other words, when braking is carried out by means of the braking device 14, the vehicle wheel is thereby braked with respect to its rotation about the wheel axis and relative to the housing 12, i.e., slowed down, or at least decelerated. The braking device 14 is a friction disc brake device, as will be explained in more detail below. The braking device 14 has a first brake disc element 16 with a first friction surface 18. Furthermore, the braking device 14 has a second brake disc element 20 with a second friction surface 22. The axle drive device 10 has a shaft 24, for example, designed as a driveshaft, wherein at least a part of the shaft 24 is rotatable about an axis of rotation 26 relative to the housing 12 and also relative to the brake disc element 16, and thus relative to the direction 28.The brake disc element 20 of the brake assembly 14, whose axial direction coincides with the axis of rotation 26 and is illustrated by a double arrow 28, also has a third friction surface 30. The brake assembly 14, whose radial direction is perpendicular to the axial direction of the brake assembly 14 and thus perpendicular to the axis of rotation 26 and is illustrated by a double arrow 32, also has a piston 34, which is also referred to as the actuating piston. When the axial direction is mentioned before and below, this refers, unless otherwise specified, to the axial direction of the brake assembly 14.When the radial direction is mentioned before and below, unless otherwise specified, this refers to the radial direction of the braking device 14, whose circumferential direction is around the axial direction and thus around the axis of rotation 26, and lies in an imaginary plane perpendicular to the axial direction and thus perpendicular to the axis of rotation 26. The circumferential direction of the braking device 14 is illustrated by a double arrow 36. The term "axial" refers to the axial direction, and the term "radial" refers to the radial direction.

[0041] The aforementioned part of the shaft 24, which is designed, for example, as a driveshaft and is rotatable about the axis of rotation 26 relative to the housing 12 and relative to the brake disc element 16, is designated 38 and is, for example, a first shaft section of the driveshaft. The driveshaft, designed, for example, as a constant velocity joint, has a joint 40 through which the first shaft section (section 38) is articulated to a second shaft section of the driveshaft (not shown in the figures) and, in particular, is coupled for torque transmission.The brake disc element 20, and thus the friction surfaces 22 and 30, are connected, in particular permanently, to torque-transmitting and rotationally fixed, at least to the part of the shaft 24, so that at least the part 38 of the shaft 24 and the brake disc element 20, and thus the friction surfaces 22 and 30, are rotatable about the axis of rotation 26 relative to the housing 12 and also relative to the brake disc element 16 and thus relative to the friction surface 18. For example, the second shaft section is coupled, or can be coupled, to the vehicle wheel in a torque-transmitting and rotationally fixed manner. Thus, the second shaft section can rotate with the vehicle wheel about the wheel's axis of rotation relative to the housing 12.

[0042] At least part 38 of the shaft 24 and thus the brake disc element 20 are, especially when the vehicle wheel is rotated around the wheel axis relative to the housing 12, rotatable with the vehicle wheel and thus rotatable around the axis 26 relative to the housing 12 and also relative to the brake disc element 16.

[0043] The electric machine can drive the shaft 24 and the brake disc element 20 via its rotor, and in particular by means of the respective drive torque, thereby rotating at least part 38 of the shaft 24 and the brake disc element 20 about the axis of rotation 26 relative to the housing 12. As will be explained in more detail below, the braking device 14 can brake the shaft 24 and, via this, the vehicle wheel with respect to their respective rotations relative to the housing 12.

[0044] At the in Fig. In the embodiment shown in Figure 1, the brake device 14 has a third brake disc element 42 with a fourth friction surface 44. The brake disc elements 16 and 42, and thus the friction surfaces 18 and 44, are at least indirectly rotationally fixed to the housing 12 and are therefore not rotatable about the axis of rotation 26 relative to the housing 12. The brake disc element 16 is axially displaceable relative to the housing 12 and preferably also relative to the brake disc element 20 and, most preferably, also relative to the brake disc element 42. The brake disc element 20 is, for example, axially displaceable relative to the housing 12 and preferably also relative to the brake disc element 16 and, more preferably, relative to the brake disc element 42. For this purpose, a toothed connection 46 is provided, which is also referred to as a drive tooth.The brake disc element 20 is connected to the part 38 by means of the toothing 46 in a torque-transmitting manner, and in particular in a rotationally fixed manner, and is thus rotatable with the part 38 about the axis of rotation 26 relative to the housing 12. However, the toothing 46 allows axial displacements of the brake disc element 20 relative to the housing 12. For example, the piston 34 is also axially movable, and in particular displaceable, relative to the housing 12 and, for example, relative to the brake disc element 16, and preferably relative to the brake disc element 20 and relative to the brake disc element 42. The brake disc element 42 is rotationally fixed to the housing 12 and is therefore not rotatable about the axis of rotation 26 relative to the housing 12. Furthermore, it is preferably provided that the brake disc element 20 is axially fixed to the housing 12 and is therefore not axially movable relative to the housing 12.The brake disc element 16 is preferably connected to the housing 12 in a rotationally fixed manner and is therefore not rotatable about the axis of rotation 26 relative to the housing 12. For this purpose, for example, a second toothed section 48 is provided, which is referred to, for example, as a second drive tooth. Thus, for example, the brake disc element 16 is connected to the housing 12 in a rotationally fixed manner by means of the toothed section 48, whereby the toothed section 48, however, allows axial displacements and displacements relative to the housing 12, i.e., translational movements of the brake disc element 16.

[0045] In this case, the piston 34 is designed as an annular piston. The piston 34 can be actuated, particularly directly, with hydraulic fluid and thus hydraulically actuated. For this purpose, a hydraulic channel 50, through which the hydraulic fluid flows, runs within the housing 12. Furthermore, an actuation chamber 52, also referred to as the working chamber, is provided, which is partially and directly bounded by the housing 12 and partially and directly by the piston 34. The hydraulic channel 50 opens into the actuation chamber 52. This allows the hydraulic fluid flowing through the hydraulic channel 50 to be introduced into the actuation chamber 52, thereby enabling the piston 34 to be actuated, particularly directly, with the hydraulic fluid.By hydraulically actuating the piston 34, the piston 34 is axially movable, i.e., in an axial direction relative to the housing 12 and, for example, also relative to the brake disc elements 16, 20 and 42, i.e., displaceable.

[0046] The brake assembly 14 also includes a transmission element 54, which is separate from the piston 34 and separate from the brake disc elements 16, 20, and 42, and which is also referred to as an actuating element. By means of the hydraulic actuation of the piston 34 described above, the transmission element 54 can be actuated by means of the piston 34 and is thereby axially movable and relative to the housing 12, i.e., displaceable. This means that the transmission element 54 is axially movable, i.e., displaceable, relative to the housing 12 and, for example, also relative to the brake disc element 20 and, in particular, relative to the brake disc element 42.By actuating the transmission element 54, the first brake disc element 16 can be actuated by means of the transmission element 54 and thereby moved axially and relative to the housing 12 and preferably also relative to the brake disc element 20 and preferably relative to the brake disc element 42, i.e., displaced. For this purpose, the transmission element 54 is, for example, at least indirectly axially rigidly connected to the brake disc element 16, so that, for example, axially directed relative movements between the first brake disc element 16 and the transmission element 54 are prevented.It can be seen that by hydraulically actuating the piston 34, the transmission element 54 and, via the transmission element 54, the first brake disc element 16 can be actuated. This allows the friction surfaces 18 and 22, and in this case also the friction surfaces 30 and 44, to be brought into direct, mutual frictional contact, thus braking the part 38 and therefore the vehicle wheel relative to the housing 12. For example, the friction surface 18 is first moved axially towards the friction surface 22 and brought into direct frictional contact with it. Furthermore, the friction surface 30 is moved axially towards the friction surface 44 and brought into direct frictional contact with it.

[0047] It can be seen that the friction surfaces 18 and 22 are axially oriented towards each other, and the friction surfaces 30 and 44 are axially oriented towards each other.

[0048] A cooling structure 56 is arranged on the rear side R of the brake disc element 16, which faces axially away from the friction surface 18 and also from the friction surface 22. The transmission element 54, for example, is connected to the brake disc element 16 via this cooling structure, in particular such that axial relative movements between the transmission element 54 and the first brake disc element 16 are prevented. The cooling structure 56 has at least one or more cooling channels, which are also referred to as first cooling channels. A preferably liquid coolant can flow through each first cooling channel, thereby advantageously cooling the brake disc element 16 and, for example, also the transmission element 54.

[0049] At the in Fig. In the embodiment shown in Figure 1, a second cooling structure 58 is provided on a wide rear side R2 of the brake disc element 42, which faces axially away from both the friction surface 44 and the friction surface 30. The second cooling structure 58 has, for example, at least one or more second cooling channels. The respective second cooling channel can be permeated by the coolant, for example, thereby advantageously cooling the third brake disc element 42.

[0050] Shaft 24 is, for example, an output shaft of the axle drive unit 10. It is conceivable that the rotor and / or shaft 24 are arranged coaxially with the vehicle wheel, so that, for example, the machine axis of rotation and / or the axis of rotation 26 coincide with the wheel axis of rotation. In particular, the axle drive unit 10 can drive the vehicle wheel at its end face via shaft 24, which functions as a drive shaft.

[0051] The housing 12 comprises a first housing part 60 and a second housing part 62, wherein the housing part 62 is, for example, a first cover of the housing 12. The first cover is also referred to as a side cover. Considering only the housing part 60, the housing part 60 has a housing opening 64, which is at least partially closed by the housing part 62. The housing parts 60 and 62 are formed separately from one another and are connected to each other at least indirectly, and in particular directly, in such a way that relative movements between the housing parts 60 and 62 are prevented. In particular, the side cover is arranged on an end face, in particular an axial face, of the housing part 60. The shaft 24 is supported in the side cover, in this case by means of at least one bearing 66 designed as a rolling bearing, which in this case is a ball bearing.

[0052] The shaft 24, designed as an output shaft, therefore runs centered on the side cover, in particular such that at least part 38 runs centered on the side cover. In particular, at least part 38 is rotatably mounted in and on the housing part 62 (side cover) by means of the bearing 66, that is, rotatably mounted about the axis of rotation 26 relative to the housing 12.

[0053] The brake disc element 20 has a pad carrier disc, also referred to simply as a carrier disc, which is, for example, a base body of the brake disc element 20. The carrier disc is centered on the toothing 46 and is thus axially displaceable relative to the shaft 24 and the housing 12, but torque-transmitting, and in particular rotationally fixed, to the part 38, in particular the shaft 24. The carrier disc is provided, for example, with a first brake pad and a second brake pad, wherein, for example, the first brake pad forms the friction surface 22 and the second brake pad the friction surface 30. It can be seen that the friction surfaces 22 and 30 are arranged on axially opposite sides of the carrier disc, with the friction surfaces 22 and 30 pointing away from each other axially.

[0054] It is conceivable that the friction surface 44 is an outer surface of the side cover (housing part 62). Thus, it would be conceivable that the brake disc element 42 is formed as a single unit with the side cover. In the case of the Fig. In the embodiment shown in Figure 1, however, the brake disc element 42 is designed separately from the side cover and connected to the side cover (housing part 62), in particular in such a way that relative movements between the side cover and the brake disc element 42 are prevented. Since, for example, the cooling structure 58 is provided here, the brake disc element 42 is a cooled, in particular liquid-cooled, brake disc.

[0055] For example, the respective cooling structure 56, 58 is formed by or designed as a respective cooling plate. Since the aforementioned, preferably liquid, coolant can flow through the respective cooling channel and thus through the respective cooling plate, the cooling plate is a cooled, in particular liquid-cooled, cooling plate. The coolant can advantageously absorb heat via the respective cooling structure 56, 58, which is generated during the aforementioned braking process, also referred to as braking, by the friction surfaces 18, 22, 30 and 44 rubbing against each other.

[0056] The brake disc element 16 is a friction disc that is connected to the housing 12, particularly to the side cover, in a torque-transmitting and, in particular, rotationally fixed manner, but is axially displaceable relative to the housing 12 and thus relative to the side cover. In particular, the brake disc element 16 is centered relative to the side cover by means of the toothing 48.

[0057] The side cover forms, that is, directly delimits, a receiving space 68, also referred to as an interior. For example, the receiving space 68 is annular. The brake disc elements 16 and 22, and preferably also the brake disc element 42, are arranged in the receiving space 68, which is formed, that is, delimited, by the side cover. The side cover at least partially closes the housing opening 64 and thus an interior space 70 of the housing 12, also referred to as a housing chamber, to the outside, i.e., towards an environment 72 of the axle drive unit 10. The interior space 70 is formed, that is, directly delimited, by the housing part 60, with, for example, the transmission and the electric motor each being at least partially arranged in the interior space 70.

[0058] The side cover is an intermediate cover arranged axially between housing part 60 and a third housing part 74 of the housing 12. Housing part 74 is separate from housing parts 60 and 62 and is connected to them at least indirectly. Housing part 74 is connected to the side cover at least indirectly, in particular such that relative movements between the side cover and housing part 74 are prevented. Specifically, housing parts 60, 62, and 74 are connected to each other in pairs such that relative movements between them are prevented when considered as a pair. Housing part 74 is also referred to as the end cover. Looking at the side cover alone, it has an opening 76 through which the receiving chamber 68 is open to the outside and thus to the surroundings 72.The end cap at least partially closes off the cover opening 76 and thus the receiving chamber 68 to the outside and therefore to the surroundings 72. It is evident that the piston 34 is at least partially located within the end cap. In this case, the piston 34 is at least partially radially arranged within the end cap. Furthermore, the piston 34 is arranged to overlap the end cap axially, at least partially. It is also evident that the hydraulic channel 50 runs within the end cap, and that the direction of actuation 52 is directly limited, partly by the piston 34 and partly by the end cap.

[0059] It is also evident that the end cap is arranged radially overlapping with the brake disc elements 20, 16 and 42, so that the brake disc elements 16, 20 and 42 are at least partially covered axially to the environment 72 by the end cap.

[0060] By hydraulically actuating the piston 34, the hydraulically actuated piston 34 presses axially against the transmission element 54 and thus, via this element, indirectly against the brake disc element 16. The transmission element 54 is frustoconical in shape to achieve advantageous force transmission. Preferably, the transmission element 54 is made of stainless steel or ceramic to prevent excessive heat transfer from the transmission element 54 to the piston 34. The aforementioned stainless steel and ceramic exhibit lower thermal conductivity compared to conventional steel or aluminum.

[0061] By bringing the friction surfaces 18 and 22 and the friction surfaces 30 and 44 into direct, friction-fit contact, a braking torque can be generated, thereby braking the shaft 24 and, via this, the vehicle wheel relative to the housing 12. This process generates braking heat.

[0062] To avoid excessively high temperatures of piston 34 and the hydraulic fluid, it is particularly well shown that Fig. 2 and Fig. As can be seen in Figure 3, the transmission element 54 has a first groove 78 and the piston 34 has a second groove 80. An intermediate element 82 is provided, formed separately from the transmission element 54 and the piston 34 and arranged in the grooves 78 and 80, by means of which the transmission element 54 and the piston 34 are connected. The intermediate element 82 is a thermally separating compensating element by means of which the piston 34 can be thermally decoupled from the transmission element 54 and thus from the friction surfaces 18, 22, 30 and 44, which is particularly advantageous. In the embodiment shown in the figures, the intermediate element 82 is formed from an elastomer and is designed as an O-ring, which makes the intermediate element 82 elastically deformable, in particular with rubber elasticity.For example, the inner diameter of the piston 34 at the location of the groove 80 is larger than the outer diameter of the transmission element 54 at that location by a radial offset that is the maximum possible due to tolerances. To prevent excessive vibrations between the piston 34 and the transmission element 54, the intermediate element 82 bridges a radial gap located at that point between the transmission element 54 and the piston 34. Furthermore, the intermediate element 82 allows the piston 34 and the transmission element 54 to be joined together in a pre-assembly step.

[0063] Out of Fig. 2 and Fig. As can be seen particularly well in Figure 3, the transmission element 54 has a projection 84 extending axially from a base region G of the transmission element 54 and away from the brake disc elements 16 and 20, in the outer circumferential surface M1 of which the first groove 78 is formed. The piston 34 has an inner circumferential surface M2 facing radially towards the outer circumferential surface M1, which surrounds the outer circumferential surface M1 and the first groove 78 in the circumferential direction. The second groove 80 is formed in the inner circumferential surface M2. Furthermore, it is provided that a chamfer F of the inner circumferential surface M2, widening axially towards the base region G, adjoins the second groove 80 at an end E of the piston 34 facing axially towards the base region G.

[0064] Fig. Figure 2 shows an unactuated state of piston 34. Fig. Figure 3 shows the piston 34 in an actuated state, which is hydraulically actuated in this state. This means that the Fig. Figure 3 shows the actuated state of piston 34 resulting from the previously described hydraulic actuation of piston 34. The piston 34 can be moved from the actuated state to the unactuated state, for example, by ending the hydraulic actuation of piston 34.

[0065] Out of Fig. 2 and Fig.Figure 3 shows that, by hydraulically actuating the piston 34, the piston 34 is axially displaceable and thus movable relative to the housing 12 and relative to the transmission element 54, and in the direction of the friction surfaces 18 and 22, under elastic deformation of the intermediate element 82. This allows an end face SF of the piston 34 to be displaceable and thus movable in direct contact with a corresponding support surface AF of the transmission element 54. This means that, in the actuated state of the piston 34, the end face SF rests directly against the corresponding end surface AF, enabling a particularly advantageous force transmission between the piston 34 and the transmission element 54. In the actuated state of the piston 34, the intermediate element 82 is elastically deformed to a greater extent than in the unactuated state of the piston 34.When the hydraulic actuation of the piston 34 is terminated, this allows at least partial elastic relaxation of the intermediate element 82, which is also referred to as an expansion effect. In other words, when the hydraulic actuation of the piston 34 is terminated to release the actuated state of the piston 34, the intermediate element 82, which was initially elastically deformed in the actuated state of the piston 34, can at least partially relax and thus spring back. This allows the piston 34, and therefore its end face SF, to be axially displaced and thus moved away from the transmission element 54 and the support surface AF. As a result, in the unactuated state of the piston 34, the end face SF is completely separated from the support surface AF.Preferably, it is provided that in the unactuated state of the piston 34 the piston 34 is completely spaced away from the transmission element 54 which is formed separately from the piston 34, thereby avoiding an undesirable, excessive transfer of heat from the transmission element 54 to the piston 34.

[0066] The piston 34 and the transmission element 54 are preferably made of a metallic material. Thus, when the brake device 14 is actuated, the piston 34 presses with its axial end face SF against the support surface AF and thus against the transmission element 54, creating direct metallic contact between the piston 34 and the transmission element 54. After the brake is released, i.e., after the hydraulic actuation of the piston 34 has ceased, the intermediate element 82, which is elastically deformed at least or exclusively axially when the piston 34 is actuated, ensures that the piston 34 and the transmission element 54 move axially away from each other and thus separate at least slightly, such that the end face SF and the support surface AF are pushed axially away from each other and thus, in particular, completely separated from each other.This prevents excessive heat transfer from the hot transmission element 54 to the piston 34.

[0067] The brake assembly 14 has a spring element 85. The spring element 85 is designed as a solid body and thus as a mechanical spring element, i.e., as a mechanical spring. In the embodiment shown in the figures, the spring element 85 is designed as an annular cup spring. By hydraulically actuating the piston 34, the spring element 85 is elastically deformable, so that in the actuated state of the piston 34, the spring element 85 provides a spring force. By means of the spring force of the spring element 85, the brake disc element 20 can be displaced axially relative to the housing 12 as a result of the cessation of the hydraulic actuation of the piston 34, in particular into its initial position, whereby, for example, the frictional contact between the friction surfaces 30 and 44 and, for example, also between the friction surfaces 18 and 22 can be broken or is broken.This releases the brake assembly 14, also referred to simply as the brake, in particular completely. In this case, the spring element 85 is attached to a toothed carrier ring. During braking, i.e., during the hydraulic actuation of the piston 34, an outer, in particular the outermost, area of ​​the spring element 85 is elastically deformed, thereby providing the spring force to return the brake disc element 20, in particular to its initial position. If, for example, the brake disc element 20 wears, the spring element 85, in addition to its elastic deformation on the toothed carrier ring, is displaced axially towards the electric motor, i.e., towards the interior 70. As a result, the brake disc element 20 is always only returned by the elastic distance. Even if the brake disc element 20 wears, the brake clearance remains at least essentially constant.

[0068] It is evident that the intermediate element 82, which functions or is designed as a decoupling element, enables the piston 34, designed as a ring brake piston, and the transmission element 54, designed here as a pressure plate, to be joined together to form an assembly unit in a simple and cost-effective manner. During the joining process of the transmission element 54 with the piston 34, the intermediate element 82 is radially compressed by means of the chamfer F of the piston 34 until the intermediate element 82 engages, or snaps into, the groove 80 of the piston 34, which is designed here as a detent groove. In the state of the intermediate element 82 being arranged in the groove 80, it is elastically deformed, particularly radially, and thus pre-stressed. For example, the groove 78 is designed as an O-ring groove.The intermediate element 82, which is partially arranged in the grooves 78 and 80, results in a quasi-positive locking connection between the transmission element 54 and the piston 34. Very high forces are required to separate the transmission element 54 and the piston 34.

[0069] By introducing hydraulic fluid, for example oil, into the actuation chamber 52, a pressure, particularly oil pressure, is generated in the actuation chamber 52, which is, for example, an annular space. This pressure is caused by the hydraulic fluid. As a result, the piston 34 moves, particularly axially, towards the transmission element 54. During this movement, the intermediate element 82 is elastically deformed and thereby compressed and overpressed, so that the end face SF comes into direct contact with the support surface AF. An actuating force resulting from the pressure is then transmitted by the piston 34 directly to the transmission element 54 via the direct contact between the support surface AF and the end face SF, and subsequently to the brake disc elements 16, 20, and 42.By ceasing the hydraulic actuation of the piston 34, also known as releasing the brake, the pressure in the actuation chamber 52 drops again, causing the piston 34 to move away from the transmission element 54. This allows the intermediate element 82 to expand again. To ensure, for example, that the intermediate element 82 expands not only radially but also axially, a shoulder 86, also referred to as a shoulder surface, is arranged in the groove 78. This shoulder is formed, for example, by the groove base of the groove 78. The shoulder 86 is conical and thus follows an imaginary cone that widens axially towards the friction surfaces 18 and 22. The shoulder 86 causes the intermediate element 82 to be pushed away from the transmission element 54 or the support surface AF when the intermediate element 82 relaxes and thus expands.Since the intermediate element 82 is supported in the groove 80 of the piston 34, which is designed, for example, as a locking groove, the piston 34 and the transmission element 54 are separated from each other, especially when the intermediate element 82 relaxes and thus expands, and by means of the intermediate element 82 the piston 34 and the transmission element 54 can be advantageously thermally isolated from each other, i.e. decoupled. Reference symbol list 10 electric axle drive units 12 cases 14 Brake system 16 first brake disc element 18 first friction surface 20 second brake disc element 22 second friction surface 24 wave 26 axis of rotation 28 Double Arrow 30 third friction surface 32 Double Arrow 34 pistons 36 Double Arrow Part 38 40 joint 42 third brake disc element 44 fourth friction surface 46 gear teeth 48 teeth 50 hydraulic channel 52 Activity area 54 Transmission element 56 Cooling structure 58 Cooling structure 60 first housing part 62 second housing part 64 Case opening 66 warehouses 68 Recording room 70 Interior 72 surroundings 74 third housing part 76 lid openings 78 first groove 80 second groove 82 Intermediate element 84 Cantilever 85 spring element 86 Shoulder AF support surface F Phase G Basic area M1 outer circumferential surface M2 inner circumferential surface SF front surface QUOTES INCLUDED IN THE DESCRIPTION

[0000] 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

[0000] DE 10 2019 100 738 B3

[0002]

Claims

Friction disc brake device (14) for a motor vehicle, comprising at least one first brake disc element (16) having at least one first friction surface (18), at least one second brake disc element (20) having at least one second friction surface (22), a piston (34) that can be actuated with hydraulic fluid and thereby hydraulically actuated, and a transmission element (54) formed separately from the piston (34), wherein the transmission element (54) and the first brake disc element (16) can be actuated by means of the piston (34) by hydraulic actuation of the piston (34), whereby the friction surfaces (18, 22) can be brought into frictional contact with each other to effect braking, characterized in that: - the transmission element (54) has a first groove (78); - the piston (34) has a second groove (80);and- in the grooves (78, 80) an intermediate element (82) is arranged, which is formed separately from the transmission element (54) and separately from the piston (34), and via which the transmission element (54) and the piston (34) are connected to each other.; Friction disc brake device (14) according to claim 1, characterized in that: - the transmission element (54) has a projection (84) axially extending from a base region (G) of the transmission element (54), in the outer circumferential surface (M1) of which the first groove (78) is formed; and - the piston (34) has an inner circumferential surface (M2) radially facing the outer circumferential surface (M1) and surrounding the outer circumferential surface (M1) and the first groove (78) in the circumferential direction of the friction disc brake device (14), in which the second groove (80) is formed. Friction disc brake device (14) according to claim 2, characterized in that an axially expanding chamfer (F) of the inner circumferential surface (M2) of the piston (34) adjoins the second groove (80) at an end (E) of the piston (34) which is axially directed towards the base region (G), Friction disc brake device (14) according to one of the preceding claims, characterized in that the intermediate element (82) is elastically deformable. Friction disc brake device (14) according to claim 4, characterized in that the intermediate element (82) is made of an elastomer and is therefore elastically deformable. Friction disc brake device (14) according to claim 4 or 5, characterized in that: - by actuating the piston (34) the piston (34) is movable axially relative to the transmission element (54) and in the direction of the friction surfaces (18, 22) under elastic deformation of the intermediate element (82), whereby an end face (SF) of the piston (34) is movable axially in direct support position with a corresponding support surface (AF) of the transmission element (54); and - in the unactuated state of the piston (34) the end face (SF) is completely spaced away from the support surface (AF). Friction disc brake device (14) according to claim 6, characterized in that in the unactuated state of the piston (34) the piston (34) is completely spaced away from the transmission element (54). Friction disc brake device (14) according to one of the preceding claims, characterized in that the intermediate element (82) is designed as an O-ring. Friction disc brake device (14) according to one of the preceding claims, characterized in that a shoulder surface (86) is arranged in at least or exactly one of the grooves (78, 82) on which the intermediate element (82) is supported, wherein the shoulder surface (86) is conical and thus extends along an imaginary cone which widens axially towards the friction surfaces (18, 22). Electric axle drive device (10) for a motor vehicle, wherein at least one friction disc brake device (14) according to one of the preceding claims is integrated into the axle drive device (10).

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