Axle drive device for a motor vehicle as well as motor vehicle

Abstract

The invention relates to an axle drive device (10) for a motor vehicle, with at least one integrated friction brake device (14), which is arranged in an inner area (68) of a cover (62) closing a drive compartment (70) and has at least one brake disc (16, 42) which has a first splined connection (47) on its outer circumference (AU1) which engages in a corresponding second splined connection (48) provided on an inner circumferential side (I) of the cover (62), whereby the brake disc (16, 42) is connected to the cover (62) in a rotationally fixed manner.

Description

[0001] The invention relates to an axle drive device for a motor vehicle, in particular for a car. Furthermore, the invention relates to a motor vehicle with at least one such axle drive device.

[0002] DE 10 2019 100 738 B3 discloses an electric axle drive unit for a motor vehicle, 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 an axle drive device for a motor vehicle and a motor vehicle with at least one such axle drive device, so that a particularly advantageous braking system can be implemented in a particularly space-saving manner.

[0004] This problem is solved by an axle drive device with the features of claim 1 and by a motor vehicle with the features of claim 7. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims.

[0005] A first aspect of the invention relates to an axle drive device for a motor vehicle, also simply referred to as a vehicle. This means that the motor vehicle, preferably designed as a motor car, in particular as a passenger car, in its fully manufactured state, has the axle drive device and can be driven by means of the axle drive device, in particular electrically and, most especially, purely electrically. For example, the motor vehicle in its fully manufactured state has at least or exactly two axles arranged consecutively in the longitudinal direction of the motor vehicle, namely a first axle and a second axle. Each axle is also simply referred to as an axle and has at least or exactly two wheels. The wheels of each axle are also referred to as wheels.The wheels of each vehicle axle are arranged on opposite sides of the vehicle in the transverse direction. The vehicle wheels are ground contact elements by which the vehicle can be supported or is supported downwards against the ground in its vertical direction. When the vehicle is driven along the ground while supported downwards by these ground contact elements, the ground contact elements roll along the ground, particularly directly. The axle drive system can, for example, drive at least or exactly one of the wheels of one of the vehicle axles. In particular, it is conceivable that the axle drive system can drive the wheels of the same vehicle axle, especially simultaneously.The vehicle wheel, in particular the respective one, that can be driven by means of the axle drive unit is also simply referred to as the drive wheel. For example, the axle drive unit has a drive motor by means of which the vehicle wheel can be driven, in particular via an output shaft of the axle drive unit. This means that the drive motor can drive the output shaft, whereby the drive wheel can be driven by driving the output shaft.

[0006] For example, the axle drive assembly has a housing, also referred to as a housing assembly, wherein the output shaft is rotatable about an output shaft axis of rotation relative to the housing assembly. Thus, for example, the drive motor can drive the output shaft, also simply referred to as the shaft, and thereby rotate it about the output shaft axis of rotation relative to the housing. By driving the output shaft, the drive wheel can be driven by means of the output shaft and thereby rotated about a wheel axis of rotation relative to the housing. It is conceivable that the wheel axis of rotation coincides with the axis of rotation. Furthermore, it is conceivable that the wheel axis of rotation is inclined to the axis of rotation, or that the wheel axis of rotation is parallel to the wheel axis of rotation and spaced apart from the axis of rotation.

[0007] The characteristic that the output shaft is rotatable about its axis of rotation relative to the housing means that at least a portion of the output shaft is rotatable about its axis of rotation relative to the housing. This portion of the output shaft could, for example, be a first shaft section, which might include a second shaft section and a joint, also known simply as a universal joint. The shaft sections are articulated together via the universal joint.

[0008] The axle drive unit has at least one integrated friction brake device. The friction brake device is referred to as a brake device, brake, or friction brake. For example, the friction brake device is or forms a service brake of the motor vehicle. By means of friction braking, the output shaft can be slowed down by friction as it rotates around its axis of rotation relative to the housing. This, in turn, slows down the rotation of the vehicle wheel around its axis of rotation relative to the housing. This, in turn, slows down the vehicle as a whole.

[0009] For this purpose, the friction brake assembly has at least one brake disc, which is also referred to as the first brake disc. Whenever the brake disc is mentioned before and below, this refers, unless otherwise specified, to the first brake disc. The first brake disc is also referred to as the first brake disc element or brake disc element. The brake disc is arranged in an interior area, also referred to as the interior or receiving area, of a cover that closes off a drive compartment of the axle drive assembly. This means, in particular, that the interior area is bounded by the cover, especially by an inner circumferential surface of the cover, and in particular directly. Most importantly, the friction brake assembly is arranged directly within the interior area of ​​the cover.The aforementioned drive compartment is, for example, bounded by the housing assembly, in particular by an inner circumferential surface of the housing assembly, and in particular directly bounded. For example, the housing assembly comprises a first housing part and a second housing part, wherein the first housing part and the second housing part are, for example, designed separately from one another and connected to each other, in particular such that relative movements between the first housing part and the second housing part are prevented. The drive compartment is, for example, bounded by the first housing part, in particular by an inner circumferential surface of the first housing part, and in particular directly bounded. The aforementioned drive machine, designed, for example, as an electric machine, is, for example, arranged in the drive compartment.Alternatively or additionally, a gearbox is arranged in the drive compartment, for example, via which the output shaft of the drive motor can be driven and thus rotated about the output shaft's axis of rotation (axis of rotation) relative to the housing. In particular, the gearbox is, for example, a differential gear. The second housing part is, for example, the aforementioned cover, which could be an intermediate cover. It is conceivable that the inner area of ​​the cover connects to the drive compartment axially, that is, in the axial direction of the axle drive unit. When the axial direction is mentioned before and in the following, unless otherwise specified, this refers to the axial direction of the axle drive unit, whose radial direction is perpendicular to the axial direction and thus perpendicular to the axis of rotation.The axial direction of the axle drive coincides with the axis of rotation. When the radial direction is mentioned before and after, this refers, unless otherwise specified, to the radial direction of the axle drive. "Axial" here means the axial direction, and "radial" means the radial direction.

[0010] The brake disc of the friction brake assembly, whose axial direction coincides with the axial direction of the axle drive assembly, has a first splined connection on its outer circumference, which faces outwards in the radial direction. This first splined connection engages with a corresponding second splined connection provided on an inner circumferential side of the cover, thereby connecting the brake disc of the friction brake assembly, whose radial direction coincides with the radial direction of the axle drive assembly, to the cover in a rotationally fixed, and in particular permanently rotationally fixed, manner. This allows for a space-saving, weight-efficient, and cost-effective, rotationally fixed connection of the brake disc to the cover and thus to the housing assembly as a whole, enabling a particularly compact design.

[0011] In order to brake the output shaft and thus the vehicle wheel in a particularly space-saving manner, one embodiment of the invention provides that the friction brake device comprises a first brake disc, a second brake disc, and a pad disc arranged, in particular axially, between the first and second brake discs, wherein the second brake disc is axially fixed to the cover, i.e., axially fixed within the cover. This means that the second brake disc is connected to the cover in such a way that axial relative movements between the second brake disc and the cover are prevented. Thus, a particularly advantageous braking mechanism can be implemented in a space-saving manner, by which the shaft and thus the vehicle wheel can be braked.

[0012] It has proven particularly advantageous to integrate a cooling plate into the second brake disc on a side facing away from the first brake disc and the pad disc, also referred to as the rear side. The cooling plate forms or comprises a cooling structure, which, for example, has at least one cooling channel through which a coolant, particularly a liquid, flows. By means of the coolant flowing through the cooling channel, the second brake disc, and thus the friction brake assembly, can be cooled effectively and efficiently in a particularly space-saving manner, resulting in particularly advantageous braking performance.

[0013] For example, particularly by actuating the friction brake device, especially hydraulically, the first brake disc can be displaced axially relative to the housing, the second brake disc, and the pad disc, and thereby moved towards the pad disc and the second brake disc. This allows the pad disc to be displaced axially relative to the housing and the second brake disc, and thus moved towards the second brake disc. This brings the second brake disc and the pad disc, and the first brake disc and the pad disc, into direct, frictional contact, thereby enabling the pad disc, and consequently the output shaft and the vehicle wheel, to be braked.The brake pad is, for example, permanently connected to the output shaft, or at least to the aforementioned part of the output shaft, in a rotationally fixed manner, so that the brake pad can rotate around the axis of rotation relative to the first brake disc and relative to the second brake disc.

[0014] Preferably, the second brake disc is connected to the cover in a rotationally fixed manner and thus to the housing assembly. For this purpose, the second brake disc, for example, has a third splined connection, particularly on its second outer circumference, which engages, for example, with the second splined connection or with a fourth splined connection, thereby connecting the second brake disc to the cover and thus to the housing in a rotationally fixed manner. In particular, the fourth splined connection can, for example, be arranged on the inner circumferential side of the cover or on another inner circumferential side of the cover.

[0015] To achieve particularly advantageous cooling in a space-saving manner, a further embodiment of the invention provides that the cooling plate has a contact surface with the cover extending in a radial direction, i.e., in the radial direction of the axle drive unit. This allows, for example, heat to be dissipated particularly advantageously, thus preventing excessive temperature of the friction brake unit. Alternatively or additionally, it is conceivable that the aforementioned cooling channel is partially and directly bounded by the cooling plate and partially and directly by the cover, so that particularly effective and efficient cooling can be achieved in a space-saving manner.

[0016] A further embodiment of the invention is characterized in that the first brake disc is arranged to be axially displaceable within the cover. This means, for example, that the first and second splined connections allow translational relative movements in the axial direction between the first brake disc and the housing assembly, and thus between the first brake disc and the cover, so that the friction brake assembly can be actuated particularly advantageously and in a space-saving manner, especially hydraulically. The first brake disc is axially displaceable, particularly relative to the housing assembly, and preferably relative to the brake pad and the second brake disc, by means of a hydraulically actuated actuating element. The actuating element is arranged in an end cap.For example, the actuating element can be pressurized with hydraulic fluid, particularly directly, and thus hydraulically actuated, thereby enabling hydraulic actuation of the braking device. As previously described, this allows the first brake disc to move towards the pad disc, and subsequently the pad disc towards the second brake disc, thus bringing the pad disc into direct, frictional contact with both the second and first brake discs. This allows the pad disc, and via the pad disc the output shaft, to be effectively braked, thereby effectively braking the vehicle wheel.

[0017] The actuating element is preferably a piston, which may preferably be designed as an annular piston. By, in particular directly, applying hydraulic fluid to the actuating element, it can be moved relative to the housing in a direction of movement. This allows the actuating element to actuate the first brake disc and thereby move the first brake disc in the direction of movement relative to the housing and preferably also relative to the second brake disc and relative to the pad disc, thus enabling the first brake disc to move towards the pad disc and the second brake disc.As a result, the first brake disc can displace the pad disc in the direction of movement relative to the housing and relative to the second brake disc, thus moving it towards the second brake disc. This allows the pad disc to come into direct, frictional contact with both the second and the first brake discs. This enables the friction disc, and via the friction disc, the output shaft and the vehicle wheel, to be braked effectively, efficiently, and in a space-saving manner.

[0018] The end cover, for example, is a third housing part of the housing. The housing parts are designed separately from one another and connected in such a way that relative movements between the housing parts are prevented when viewed in pairs. For example, at least a portion of the aforementioned cover is arranged in the axial direction of the axle drive unit between the first housing part and the end cover (third housing part), so that, for example, the cover is a so-called intermediate cover.

[0019] Looking at the first housing part alone, for example, the drive compartment, and thus the first housing part, has a housing opening that, when viewed from this perspective, leads at one end into the drive compartment and at the other end into the surrounding area. For example, the housing opening, and thus the drive compartment, is at least partially closed by the cover (intermediate cover), particularly towards the surrounding area. Looking at the cover alone, for example, the inner area of ​​the cover, and thus the cover itself, has a cover opening that leads at one end into the inner area of ​​the cover and at the other end into the surrounding area. In this case, for example, the cover opening, and thus the inner area of ​​the cover, is at least partially closed by the end cap, particularly towards the surrounding area.

[0020] Finally, it has proven particularly advantageous if the cover forms a counter plate for the friction braking device. This allows the braking system described above to be implemented in a particularly space-saving manner.

[0021] A second aspect of the invention relates to a motor vehicle, also referred to simply as a vehicle, and preferably designed as a motor car, in particular as a passenger car, which has at least one axle drive device according to the first aspect of the invention. 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.

[0022] 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.

[0023] 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.

[0024] In the figures, identical or functionally equivalent elements are provided with the same reference symbols.

[0025] 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.

[0026] 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.

[0027] 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; that is, it is 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.

[0028] The brake disc element 20 can also be referred to as a pad disc and has a pad carrier disc, also simply referred to as a carrier disc, which is, for example, a base body of the brake disc element 20. The carrier disc is provided, in particular, with the first brake pad and the second brake pad, wherein, for example, the first brake pad forms the friction surface 22 and a second brake pad forms a third 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.

[0029] The axle drive assembly 10 has a shaft 24, for example, a driveshaft, wherein at least a portion 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 18. An axial direction of the brake disc element 20 coincides with the axis of rotation 26 and is illustrated by a double arrow 28. 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 an actuating piston. When the axial direction is mentioned before and after, 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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 in a torque-transmitting manner, and in particular in a rotationally fixed manner, by means of the toothing 46, and is thereby 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 42 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.

[0034] 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.

[0035] 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 element 18 is first moved axially towards the friction surface 22 and moved into direct frictional contact with it. Furthermore, the friction surface 30 is moved axially towards the friction surface 44 and moved into direct frictional contact with it.

[0036] 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.

[0037] 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.

[0038] At the in Fig. In the embodiment shown in Figure 1, a second cooling structure 58 is provided on a further 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.

[0039] 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.

[0040] 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.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.

[0041] The carrier disc of the brake disc element 20 is arranged centrally on the toothing 46 and is therefore axially displaceable relative to the shaft 24 and relative to the housing 12, but torque-transmitting, in particular rotationally fixed, connected to the part 38, in particular the shaft 24.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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 actuation chamber 52 is directly bounded partly by the piston 34 and partly by the end cap.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] The brake device 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 a ring 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.

[0056] By means of the spring force of the spring element 85, the brake disc element 20 is axially displaceable 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, thereby releasing, for example, the frictional contact between the friction surfaces 30 and 44 and, for example, also between the friction surfaces 18 and 22. This releases, in particular completely, the brake device 14, also simply referred to as the brake. 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 and thereby provides the spring force to return the brake disc element 20, in particular to its initial position.For example, if the brake disc element 20 wears down, 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. This means that the brake disc element 20 is always only reset by the elastic distance. Even if the brake disc element 20 wears down, the brake clearance remains essentially constant.

[0057] 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, also referred to as joining, 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 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.

[0058] 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.

[0059] The receiving chamber 68 is also referred to as the interior and is an internal area of ​​the housing part 62, which at least partially closes off the housing opening 64 and thus the interior space 70, also referred to as the drive chamber, from the surroundings 72. The braking device 14, also referred to as and designed as a friction braking device, is arranged, in particular directly, in the internal area (receiving chamber 68) of the first cover (housing part 62).

[0060] It can be seen that brake disc element 16 is a first brake disc and brake disc element 42 is a second brake disc of the brake assembly 14. Brake disc element 20 is a pad disc of the brake assembly 14.

[0061] Out of Fig.As can be seen in Figure 1, the first brake disc (brake disc element 16) has a first splined connection 47 on its outer circumference AU1, which engages with the corresponding splined connection 48, designed as a second splined connection and provided on an inner circumferential surface I of the housing part 62. This connects the brake disc element 16 (first brake disc) to the housing part 62 and thus to the housing 12 in a rotationally fixed manner. The splined connection 47 and the splined connection 48, also referred to as a drive connection, allow the first brake disc to be displaced axially in the direction of the axle drive assembly 10 and relative to the housing 12, so that it can be moved towards the brake disc element 20 and the brake disc element 41, as described above.

[0062] The second brake disc (brake disc element 42) has a third splined connection 49 on its second outer circumference AU2, which engages with the corresponding splined connection 48, thereby permanently connecting the brake disc element 42 to the housing part 62 and thus to the housing 12. The second brake disc, i.e., the brake disc element 41, is axially fixed to the housing part 62 and thus to the housing 12. It is also evident that the pad disc (brake disc element 20) is arranged axially between the first brake disc element 16 and the brake disc element 42. The brake disc elements 16 and 42 are, in particular permanently, rotationally fixed to the housing part 62 and thus to the housing 12, whereby the pad disc (brake disc element 20) is rotatable about the axis of rotation 26 relative to the housing 12 and thus relative to the brake disc elements 16 and 42, at least with part 38.

[0063] For example, the respective cooling plate forming the cooling structure 56, 58 is integrated into the respective brake disc element 16, 42, specifically on the respective rear side R, R2 facing away from the pad disc in the axial direction. The cooling plate forming the cooling structure 58, for example, has a contact surface with the housing part 62 extending radially in the direction of the axle drive unit 10. As previously explained, the first brake disc is arranged to be axially displaceable in the housing part 62 and can be axially displaced by means of the piston 34. Thus, the piston 34 is a hydraulically actuated actuating element located in the housing part 74. Furthermore, it is provided, for example, that the housing part 62 forms a counter plate for the brake assembly 14. 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 47 first splined connection 48 teeth 49 third splined connection 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 AU1 External circumference AU2 External circumference I Inner circumference side 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

Axle drive device (10) for a motor vehicle, with at least one integrated friction brake device (14) which is arranged in an inner area (68) of a cover (62) closing a drive compartment (70) and has at least one brake disc (16, 42) which has a first splined connection (47) on its outer circumference (AU1) which engages in a corresponding second splined connection (48) provided on an inner circumferential side (I) of the cover (62), whereby the brake disc (16, 42) is connected to the cover (62) in a rotationally fixed manner. Axle drive device (10) according to claim 1, characterized in that the friction brake device (16) has at least one brake disc (16, 42) as the first brake disc (16), a second brake disc (42) and a pad disc (20) arranged between the brake discs (16, 42), wherein the second brake disc (42) is axially fixed to the cover (62). Axle drive device (10) according to claim 2, characterized in that a cooling plate is integrated into the second brake disc (42) on a side (R2) facing away axially from the first brake disc (16) and the pad disc (20). Axle drive device (10) according to claim 3, characterized in that the cooling plate has a contact surface extending in a radial direction with the cover (62). Axle drive device (10) according to one of claims 2 to 4, characterized in that the first brake disc (16) is arranged axially displaceable in the cover (62) and is axially displaceable by a hydraulically actuated actuating element (34) arranged in a final cover (74). Axle drive device (10) according to one of the preceding claims, characterized in that the cover (62) forms a counter plate of the friction brake device (14). Motor vehicle, with an axle drive device (10) according to one of the preceding claims.

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