Axle drive device for a motor vehicle, and motor vehicle

Abstract

The invention relates to an axle drive device (10) for a motor vehicle, comprising at least one integrated friction brake device (14) which is arranged in an interior (68) of an intermediate cover (62) which closes a transmission chamber (70), comprising an output shaft (24), and comprising an end cover (74) which is conically annular on the outer circumferential side at least in a partial region, is arranged coaxially with respect to the output shaft (24) which can be rotated relative to the end cover (74), extends along the output shaft (24), and closes the interior (68) of the intermediate cover (62), and comprising an actuating piston (34) which can be applied with a hydraulic fluid in order to hydraulically actuate the friction brake device (14) and which can thereby be moved in a movement direction and which directly delimits an actuating chamber (52), into which the hydraulic fluid can be introduced in order to apply the hydraulic fluid to the actuating piston (34), wherein the actuating chamber (52) and the actuating piston (34) are arranged on an inner circumference of the end cover (74), and the actuating piston (34) is in the form of an annular piston, with a direction of movement running in the axial direction of the output shaft (24).

Description

[0001] Mercedes-Benz Group AG

[0002] Axle drive device for a motor vehicle as well as motor vehicle

[0003] 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.

[0004] DE 102019 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.

[0005] 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 the motor vehicle can be braked in a particularly space-saving manner.

[0006] 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 6. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims.

[0007] A first aspect of the invention relates to an axle drive device for a motor vehicle, also referred to simply as a vehicle. This means that the motor vehicle, preferably designed as a motor vehicle, 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. The axle drive device has at least one integrated friction brake device, which can, for example, be designed as a disc brake device, i.e., as a disc brake. The friction brake device is arranged in an interior space of an intermediate cover that closes off a transmission compartment. The axle drive device has, for example, a housing comprising a first housing part and a second housing part.For example, the first housing part and the second housing part are designed 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 first housing part and the second housing part are prevented. The gear 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 intermediate cover is, for example, the second housing part. Considering only the first housing part, the first housing part has a first through-opening which, for example, opens at one end into the gear compartment and at the other end into the surrounding area of ​​the first housing part.The first through-opening, and thus the gearbox compartment, is at least partially, and in particular at least predominantly, and thus at least more than half, closed off by the intermediate cover, especially towards the environment. The feature that the friction brake device is arranged in the interior of the intermediate cover means, in particular, that the friction brake device is arranged radially within the intermediate cover and axially overlapping it. The interior is bounded, for example, by the intermediate cover, in particular by an inner circumferential surface of the intermediate cover, and in particular directly bounded, especially in the radial direction of the axle drive device towards the outside.

[0008] The axle drive unit also has an output shaft which is rotatable about an output shaft axis relative to the intermediate cover and also relative to the first housing part. This means, in particular, that at least a portion of the output shaft, whose axial direction coincides with the output shaft axis, is rotatable about the output shaft axis relative to the first housing part and relative to the intermediate cover. For example, a gearbox of the axle drive unit is arranged in the gearbox compartment, the axial direction of which coincides with the output shaft axis and thus with the axial direction of the output shaft. For example, the output shaft can be driven via the gearbox and is therefore rotatable about the output shaft axis relative to the first housing part and relative to the intermediate cover (second housing part).The axle drive assembly, whose radial direction is perpendicular to the output shaft's axis of rotation and thus perpendicular to the axial direction of the axle drive assembly, also has an end cover. For example, the end cover is a third housing part and thus also a sub-housing. The end cover is connected, for example, at least indirectly to the intermediate cover and to the first housing part, in particular in such a way that relative movements between the end cover and the intermediate cover and relative movements between the end cover and the first housing part are prevented. The intermediate cover and the end cover are also simply referred to as covers. The intermediate cover is also referred to as a side cover.

[0009] For example, a fully manufactured motor vehicle has at least one wheel, also simply referred to as a wheel. The wheel is a ground contact element by which the motor vehicle can be supported or is supported downwards against the ground in its vertical direction. The aforementioned wheel is also referred to as the first wheel. When the term "wheel" is used before and below, it refers to the first wheel unless otherwise specified. When the motor vehicle is driven along the ground while supported downwards in its vertical direction by the ground contact element, the ground contact element rolls along the ground, particularly directly.The vehicle wheel, for example, is rotatable about a wheel axis relative to the housing of the axle drive unit, so that the vehicle wheel rotates about the wheel axis relative to the housing, particularly when it rolls, especially directly, on the ground. In particular, the output shaft can be coupled to the vehicle wheel in a torque-transmitting manner, so that by driving the output shaft, the vehicle wheel can be driven by the output shaft. The output shaft can be driven, in particular via the transmission. For example, the axle drive unit has a drive motor by means of which, for example via the transmission, the output shaft can be driven and thus rotated about the output shaft axis relative to the housing. By driving the output shaft, the vehicle wheel can be driven by the output shaft and thus rotated about the wheel axis relative to the housing, thereby enabling the vehicle to be driven.The drive machine, for example, has a machine shaft via which it can provide drive torque to propel the vehicle wheel. With respect to the torque flow along which the respective drive torque can be transmitted from the machine shaft to the vehicle wheel to propel it, the transmission is located downstream of the machine shaft, the output shaft downstream of the transmission, and the vehicle wheel downstream of the output shaft. This allows the vehicle wheel to be driven by the output shaft and, via the output shaft, by the transmission, and vice versa. The drive machine is, for example, an electric motor. In principle, it would be conceivable for the wheel's axis of rotation to coincide with the output shaft's axis of rotation.Furthermore, it is conceivable that the wheel axis of rotation is spaced apart from the output shaft axis of rotation and runs parallel to the output shaft axis of rotation. It is conceivable that the instantaneous distance between the wheel axis of rotation and the output shaft axis varies depending on the current compression or rebound state of the ground contact element. It is also conceivable that the aforementioned part of the output shaft is a first shaft section of the output shaft. In this case, the output shaft can have a joint, also referred to as a universal joint, and a second shaft section, which is connected to the first shaft section, for example, via the joint, in a torque-transmitting and pivoting manner. The output shaft is thus, for example, a universal joint. The second shaft section can be connected to the vehicle wheel in a torque-transmitting or direct way.With respect to the aforementioned torque flow, the joint is located downstream of the first shaft section, the second shaft section downstream of the joint, and the vehicle wheel downstream of the second shaft section. The joint allows movements, particularly pivoting movements, of the second shaft section and thus, for example, of the vehicle wheel relative to the first shaft section, thereby permitting, for instance, compression and rebound movements of the vehicle wheel.

[0010] For example, the friction brake device can be used to brake, or slow down, the output shaft with respect to rotations around the output shaft's axis of rotation and relative to the housing. This, in turn, can brake, or slow down, the vehicle wheel with respect to rotations around the wheel's axis of rotation and relative to the housing. This allows the vehicle as a whole to be braked, or slowed down. For example, the vehicle wheel is permanently coupled, or connected, to the output shaft in a torque-transmitting manner. The friction brake device is, or forms, a friction brake by means of which the output shaft, and thus, for example, the vehicle wheel, can be braked by friction. In particular, the friction brake device is, or forms, a service brake of the vehicle.

[0011] The output shaft, or at least the aforementioned part of the output shaft, is rotatable around the output shaft axis relative to the first housing part, relative to the intermediate cover, and relative to the end cover.

[0012] The end cap has a conical ring shape on its outer circumference, at least in a portion of its circumference. Furthermore, the end cap is arranged coaxially with the output shaft, which is rotatable relative to the end cap.Because the end cap is formed in a conical ring shape on its outer circumference, at least in the aforementioned sub-area, the end cap is formed on its outer circumference in the form of a cone or conical ring, whose imaginary central axis, also referred to as the cone central axis, with respect to which the cone or conical ring is rotationally symmetrical, runs parallel to the output shaft axis of rotation and is spaced apart from the output shaft axis of rotation, or coincides with the output shaft axis of rotation, i.e., with the axial direction of the output shaft, whose radial direction is perpendicular to the output shaft axis of rotation and thus perpendicular to the axial direction of the output shaft.When the axial direction is mentioned below, unless otherwise specified, this refers to the axial direction of the output shaft and thus the axial direction of the axle drive unit, whose axial direction coincides with the axial direction of the output shaft. When the radial direction is mentioned before and below, unless otherwise specified, this refers to the radial direction of the axle drive unit and thus the radial direction of the output shaft, whose radial direction coincides with the radial direction of the axle drive unit.

[0013] The end cap extends at least along a portion of the output shaft's length. Furthermore, the end cap seals the interior of the intermediate cap. This means that, considering only the intermediate cap, it has a second through-opening that opens at one end into the interior of the intermediate cap and at the other into the surrounding area. For example, the output shaft penetrates the interior and the second through-opening, and thus the intermediate cap, axially, and in particular completely. The end cap seals the second through-opening, and thus the interior, at least partially, and in particular at least predominantly, and therefore at least more than halfway, especially towards the surrounding area of ​​the intermediate cap.The end cover is arranged coaxially to the output shaft, which is rotatable about the output shaft's axis of rotation relative to the end cover and relative to the intermediate cover, and extends in particular in the axial direction of the output shaft at least along the length of the output shaft.

[0014] The axle drive unit also features an actuating piston, which, when actuated, engages the friction brake. By actuating the friction brake, the output shaft, and thus, for example, the vehicle wheel, can be braked. In other words, by actuating the friction brake, braking of the output shaft, and therefore, in particular, the vehicle wheel, can be effected, with the friction brake being actuated by actuating the actuating piston. The actuating piston is also simply referred to as the piston.

[0015] The actuating piston is hydraulically actuated, and the friction brake device is hydraulically actuated by hydraulic actuation of the actuating piston. The piston can be pressurized with hydraulic fluid, particularly directly, for the hydraulic actuation of the friction brake device. By pressurizing the actuating piston with hydraulic fluid, particularly directly, the actuating piston and thus the friction brake device are hydraulically actuated, making the output shaft brakeable. By hydraulically actuating the actuating piston, the actuating piston can be moved in a direction of movement, particularly relative to the housing and, for example, relative to the output shaft. The actuating piston is a component of a hydraulic actuating device, which can be hydraulically actuated by hydraulically actuating the actuating piston.By hydraulically actuating the actuating device, the friction brake, also simply referred to as a braking device, can be hydraulically actuated, thereby allowing the output shaft and thus, for example, the vehicle wheel to be braked. For this purpose, the actuating piston directly defines an actuating chamber, which is, for example, another component of the actuating device. Hydraulic fluid can be introduced into the actuating chamber, allowing the actuating piston to be actuated, particularly directly, by hydraulic fluid and thus be hydraulically actuated.

[0016] In the axle drive device according to the invention, the actuating chamber and the actuating piston are arranged on an inner circumference of the end cover. This means, in particular, that the actuating chamber and the actuating piston are each arranged at least partially radially within the end cover and axially overlapping the end cover. Furthermore, the actuating piston is designed as an annular piston. This means that the actuating piston is annular in at least a portion of its length and thus designed as a ring, the central axis of which is rotationally symmetrical with respect to the ring, for example, running parallel to the output shaft axis of rotation, i.e., parallel to the axial direction, and spaced apart from the output shaft axis of rotation, i.e., the axial direction, or coinciding with the output shaft axis of rotation, i.e., the axial direction.Furthermore, according to the invention, the direction of movement is axial to the output shaft. The feature that the friction brake device is integrated, i.e., integrated into the axle drive unit, means that at least the actuation chamber and the actuation piston are arranged on the inner circumference of the end cap, i.e., radially within the end cap and axially overlapping with the end cap. This allows the friction brake device to be integrated into the axle drive unit in a particularly space-saving manner, thereby enabling the output shaft, and thus, for example, the vehicle wheel, to be braked in a particularly space-saving manner.

[0017] Conventionally, a braking device for braking a vehicle wheel requires a complex, and therefore space-intensive, installation, for example, inside the vehicle wheel. This can now be avoided by the invention. The invention enables a particularly space-saving arrangement of the friction brake device, and in particular of the actuation chamber and the actuating piston. Furthermore, a particularly advantageous centering of components of the axle drive system can be achieved. It is conceivable that the friction brake device could also be integrated in the described manner into an axle transmission, a differential transmission, or a chassis component such as an axle carrier. The aforementioned transmission is, for example, a differential transmission.

[0018] A further advantage of the invention is that, because the end cap is designed in a conical ring shape, it has a conical contour, at least in that portion of the end cap. This allows for a particularly high rigidity of the end cap to be achieved in a space-saving manner, enabling the end cap to be designed as a particularly rigid cap. Such high rigidity of the end cap is advantageous because, for example, the end cap directly defines the actuation chamber, in which a particularly high pressure of the hydraulic fluid, which may be contained at least temporarily, can prevail.The hydraulic fluid pressure in the actuating chamber, intended for the hydraulic actuation of the actuating piston and thus the friction brake device, can, for example, be in a range from 80 bar to 100 bar inclusive. Due to its high achievable stiffness, the end cover can advantageously withstand this high pressure without sustaining damage or undesirable deformation. The invention enables a space-saving overall arrangement, since the end cover (also referred to simply as the cover), the actuating chamber, and the actuating piston can be installed in a space outside the first housing part and, in particular, outside the intermediate cover. This space is specifically designed such that it adjoins the first housing part and, in particular, the intermediate cover in the axial direction.The invention also enables a particularly advantageous supply of hydraulic fluid to the actuating chamber. In other words, a particularly advantageous introduction of the hydraulic fluid into the actuating chamber can be achieved without a rotary feeder. For this purpose, for example, at least one supply channel through which the hydraulic fluid flows is located within the end cover, which opens, in particular directly, into the actuating chamber, so that the hydraulic fluid can be introduced into the actuating chamber via the supply channel. A rotary feeder of the hydraulic fluid into the actuating chamber can be avoided, thereby preventing excessive leakage resulting from the high pressure of the hydraulic fluid.Since, for example, high temperatures of up to several hundred degrees can occur at the friction brake device, in particular at least at one friction element of the friction brake device, a brake fluid is used as the hydraulic fluid, which differs, for example, from an oil used in the rest of the drive device for lubricating and / or cooling the rest of the axle drive device.

[0019] To achieve a particularly space-saving design, one embodiment of the invention provides that the output shaft has a tripod joint. Specifically, the tripod joint is the aforementioned joint, i.e., a shaft joint. For achieving a particularly compact and thus space-saving design, it has proven especially advantageous if the tripod joint is completely surrounded by the end cap in the circumferential direction of the output shaft, extending around the output shaft's axis of rotation and thus around the axial direction of the output shaft, and thus over 360 degrees, so that a central axis of the end cap coincides with a central axis of the output shaft. The central axis of the end cap is, for example, the aforementioned central axis of the cone or conical ring, and the central axis of the output shaft is, for example, the output shaft's axis of rotation.

[0020] A further embodiment of the invention is characterized by the provision of a sealing element, for example designed as a shaft seal, which is formed, for example, from an elastomer, in particular from rubber. The sealing element is arranged radially along the output shaft between a sleeve that rotates with the output shaft relative to the end cap and the end cap. For example, the sleeve is connected, at least indirectly, in particular directly, to the output shaft in a rotationally fixed manner, in particular permanently rotationally fixed, that is, at least to the aforementioned part of the output shaft. The sealing element is arranged radially inside the end cap and axially overlapping the end cap, and the sealing element is arranged radially outside the sleeve and axially overlapping the sleeve. The sleeve surrounds the tripod joint in the circumferential direction of the output shaft, in particular completely around and thus over 360 degrees.In particular, the sleeve is designed separately from the aforementioned part of the output shaft and is, in particular, permanently and rotationally fixed to the aforementioned part of the output shaft. Because the sealing element is arranged radially between the end cap and the sleeve, the end cap is sealed at least radially, i.e., in the radial direction, against the sleeve by means of the sealing element. For example, the sealing element is, in particular, permanently and rotationally fixed to the end cap, so that, for example, the output shaft, or at least that part of the output shaft, is rotatable about the output shaft's axis of rotation relative to the sealing element. For example, the sealing element, in particular a sealing lip of the sealing element, rests directly against an outer circumferential surface of the sleeve, which is rotatable about the output shaft's axis of rotation relative to the sealing element along with the output shaft, or at least with that part of the output shaft.As the output shaft, and thus the sleeve, rotates around the output shaft's axis of rotation relative to the end cap and the sealing element, the sealing element, particularly the sealing lip, slides directly along the outer circumferential surface of the sleeve. This allows for an effective, efficient, and space-saving seal. Specifically, because the end cap is sealed against the sleeve by means of the sealing element, the interior space of the intermediate cover (also referred to as the first interior space) is sealed, as is, for example, a second interior space of the end cap, particularly from the aforementioned environment of the axle drive unit.In this case, for example, the actuation chamber and the actuation piston are each at least partially arranged in the second interior space of the end cover, wherein, for example, the second interior space is limited, in particular directly limited, by the end cover, in particular by an inner circumferential surface of the end cover.

[0021] To enable the output shaft, and thus in particular the vehicle wheel, to be braked in a particularly space-saving manner, a further embodiment of the invention provides that the actuating piston has a step which forms an effective surface of the actuating piston. At least the effective surface directly delimits, for example, the actuating chamber, so that, for example, by introducing hydraulic fluid into the actuating chamber, the effective surface and thus the actuating piston can be directly actuated by the hydraulic fluid. For example, the effective surface extends in a plane that runs obliquely or perpendicular to the axial direction. This allows the actuating piston to be moved in the direction of movement, and thus in the axial direction, particularly relative to the housing and especially relative to the output shaft, by directly acting the effective surface with the hydraulic fluid, in order to actuate the friction braking device.

[0022] A second aspect of the invention relates to a motor vehicle, also referred to simply as a vehicle, and preferably designed as a motor vehicle, in particular as a passenger car, which has at least one drive unit according to the first aspect of the invention and can be driven by means of the axle drive unit, in particular electrically and most especially purely electrically. 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.

[0023] 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 single figure 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.

[0024] The drawing shows in the single Fig. 1 a partial schematic sectional view of an electric axle drive device of a motor vehicle, wherein a friction brake device, in this case designed as a friction disc brake device, is integrated into the electric axle drive device.

[0025] Fig. 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, 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 18.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.

[0028] 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, which is 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 the part of the shaft 24 in a torque-transmitting manner, and in particular in a rotational manner, such 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 manner, and in particular in a rotational manner. Thus, the second shaft section can rotate with the vehicle wheel about the wheel's axis of rotation relative to the housing 12.

[0029] 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.

[0030] The electric machine can drive the shaft 24 via its rotor, and in particular by means of the respective drive torque, as well as the brake disc element 20, 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.

[0031] In the embodiment shown in Fig. 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, and in particular rotationally fixed, manner by means of the toothing 46, 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.

[0032] 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, that is, in the axial direction relative to the housing 12 and, for example, also relative to the brake disc elements 16, 20, and 42. The brake assembly 14 also has a transmission element 54, which is separate from the piston 34 and separate from the brake disc elements 16, 20, and 42 and 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 relative to the housing 12. This means that the transmission element 54 is translationally movable, that is, displaceable, axially 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 effecting braking of the part 38 and therefore of 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.

[0033] 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.

[0034] 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.

[0035] In the embodiment shown in Fig. 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.

[0036] 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.

[0037] 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 centrally to the side cover, in particular such that at least part 38 runs centrally to 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. The brake disc element 20 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 arranged centrally on the toothing 46 and is thus axially displaceable relative to the shaft 24 and relative to the housing 12, but torque-transmitting, in particular rotationally fixed, to part 38, in particular to 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 forms 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.

[0038] 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 integrally with the side cover. However, in the embodiment shown in Fig. 1, the brake disc element 42 is formed 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.

[0039] 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.

[0040] 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. The side cover forms, that is, delimits, a receiving space 68, also referred to as an interior, in particular directly. 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, i.e., limited, 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 the housing space, to the outside, i.e., towards the surroundings 72 of the axle drive unit 10. The interior space 70 is formed, i.e., in particular directly limited, 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] The interior 70 of the housing 12 is a transmission compartment, also referred to as the transmission chamber. It is evident that the intermediate cover at least partially closes off the transmission compartment, particularly towards the surrounding area 72. Since the brake disc elements 16 and 22, and in this case also the brake disc element 42, are arranged in the receiving space 68 (interior of the intermediate cover), the brake assembly 14, also designed as a friction brake assembly and thus referred to as the friction brake assembly, is arranged in the receiving space 68, thereby integrating the brake assembly 14 into the axle drive assembly 10 in a space-saving manner.

[0046] To achieve particularly high rigidity of the end cover (housing part 74) in a space-saving manner, the end cover is formed with a conical ring shape on its outer circumference, at least in a partial area TB of the end cover. The end cover is arranged coaxially with the shaft 24, which is rotatable about the axis of rotation 26, also referred to as the output shaft axis, relative to the first housing part 60, relative to the intermediate cover (second housing part 62), and relative to the end cover (third housing part 74). This means that at least part 38 is rotatable about the axis of rotation 26 relative to the housing parts 60, 62, and 74.

[0047] As can be seen from Fig. 1, the end cover (third housing part 74) is arranged coaxially with the shaft 24, which is rotatable about the axis of rotation 26 relative to the end cover, in particular such that a central axis, with respect to which the conical ring-shaped section TB is rotationally symmetrical, coincides with the axis of rotation 26. Furthermore, the end cover extends along the output shaft (shaft 24). In addition, the receiving space 68 of the intermediate cover is at least partially closed off by the end cover, particularly towards the surroundings 72.

[0048] It is also evident that the piston 34, also referred to as the actuating piston, can be directly pressurized with hydraulic fluid for the hydraulic actuation of the brake device 14 and is thus movable in a direction of movement illustrated by arrow 88. Starting from the piston 34, the direction of movement extends towards the brake disc elements 16, 20, and 42 and away from the actuation chamber 52, which is directly delimited by the piston 34. The end cap also directly delimits the actuation chamber 52. To pressurize the piston 34 with hydraulic fluid and thus directly actuate it hydraulically, the hydraulic fluid can be introduced into the actuation chamber 52 via the hydraulic channel 50.

[0049] It can be seen that the actuation chamber 52 and the piston 34 are arranged on an inner circumference of the end cover, such that the actuation chamber 52 and the piston 34 are each arranged at least partially, in particular at least predominantly and thus at least to more than half, radially within the end cover and axially overlapping the end cover. Furthermore, the piston 34 is designed as an annular piston, the direction of movement of which, illustrated by arrow 88, runs in the axial direction of the shaft 24 and thus along the axis of rotation 26.

[0050] Within the scope of this disclosure, the feature "radially overlapping" is to be understood as follows: Two elements, in particular those that are essentially rotationally symmetrical, are arranged in a radially overlapping manner, in particular with respect to a common axis extending, for example, in the radial direction of the axle drive device and / or in the radial direction of the axle drive device, if they are each arranged at least partially in a region of identical radial coordinates, in particular identical angular coordinates, wherein the radial coordinates extend in the radial direction and in particular begin at the output shaft axis of rotation. The term "radial" refers to the radial direction. In other words, the term "radial" means the radial direction.

[0051] The feature "axially overlapping" means the following: Two elements are arranged axially overlapping with respect to a common axis, particularly one extending in the axial direction, and / or with respect to the axial direction of the axle drive device, if they are each arranged at least partially within a region of identical axial coordinates extending along the axial direction. Within the scope of this disclosure, the term "axial" refers to the axial direction. In other words, the term "axial" means the axial direction. Put another way, "axial" refers to the axial direction, and "radial" refers to the radial direction.

[0052] Within the scope of this disclosure, the feature that a first component is arranged radially inside a second component means that the first component is arranged in a region of smaller radii than the second component, particularly with respect to the output shaft axis of rotation, wherein said radii extend in a radial direction and, in particular, originate at the output shaft axis of rotation. Within the scope of this disclosure, the feature that a first component is arranged radially outside a second component means that the first component is arranged in a region of larger radii than the second component, particularly with respect to the output shaft axis of rotation, wherein said radii extend in a radial direction and, in particular, originate at the output shaft axis of rotation.

[0053] Within the scope of the present disclosure, the feature that two components are rotationally fixed to one another is understood to mean that the rotationally fixed components are arranged coaxially to one another and, in particular when the components are driven, rotate together or simultaneously about a common axis of rotation of the components, such as the axis of rotation of the output shaft, at an angular velocity, especially relative to a reference element such as the housing. In other words, two components are rotationally fixed to one another if they are arranged coaxially to one another, especially with respect to their axis of rotation or with respect to an axis of rotational symmetry, and if they are connected to one another in such a way that they always rotate at the same angular velocity.

[0054] The characteristic that two components are connected or coupled to each other in a torque-transmitting manner means that the components are coupled or connected in such a way that torques can be transmitted between them. If the components are connected or coupled in a rotationally fixed manner, they are also connected or coupled in a torque-transmitting manner. Two components connected in a torque-transmitting manner can therefore be connected in a rotationally fixed manner.Furthermore, it is conceivable that two torque-transmitting components are connected to each other via an intermediate transmission and / or coupling unit, so that torques can be transmitted between the components via the transmission and / or coupling unit, while the components are connected to each other in a torque-transmitting manner, whereby the components can be rotatable relative to each other.

[0055] The characteristic that two components are permanently connected or coupled in a torque-transmitting manner means that there is no switching element that can be toggled between a coupling state in which the components are connected or coupled in a torque-transmitting manner and a decoupling state in which no torque can be transmitted between the components via the switching element. Rather, the components are always and therefore permanently torque-transmitting, meaning they are connected or coupled in such a way that torque can be transmitted between them. Thus, for example, one component can be driven by the other, and vice versa.

[0056] The characteristic that two components are permanently connected or coupled to each other in a rotationally fixed manner means that a switching element is not provided which can be switched between a coupling state in which the components are connected or coupled in a rotationally fixed manner and a decoupling state in which the components are decoupled from each other and rotatable relative to each other, so that no torques can be transmitted between the components via the switching element, but rather the components are always, i.e., permanently connected or coupled to each other in a rotationally fixed manner.

[0057] Preferably, the joint 40 is a tripod joint. It can be seen that the joint 40 is completely surrounded by the end cap in the circumferential direction of the shaft 24, which extends around the axial direction of the shaft 24 and thus around the axis of rotation 26, such that a central axis of the end cap coincides with a central axis of the shaft 24. In particular, the central axis of the shaft 24 is the axis of rotation 26. The central axis of the end cap is, for example, the aforementioned central axis, with respect to which the conical ring-shaped section TB is rotationally symmetrical.

[0058] The axle drive unit 10 also comprises a sealing element 90, preferably at least partially formed from an elastomer, in particular from rubber, which is preferably designed as a shaft seal, in particular as a radial shaft seal. The sealing element 90 is arranged radially to the shaft 24 and thus to the axle drive unit 10 between a sleeve 92, which is rotatable with the shaft 24 about the axis of rotation 26 relative to the end cover, the intermediate cover, and the first housing part 60, and the end cover, so that the end cover is sealed against the sleeve 92 by means of the sealing element 90. The sleeve 92 surrounds the joint 40 in the circumferential direction of the shaft 24, in particular completely. For example, the sleeve 92 is formed separately from the part 38 and is, in particular, permanently and rotationally fixed to the part 38.Furthermore, the piston 34 has a step 94, which forms an effective surface 96 of the piston 34. In particular, the effective surface 96 directly delimits the actuation chamber 52.

[0059] To prevent excessively high temperatures of the piston 34 in the hydraulic fluid, for example, the transmission element 54 has a first groove and the piston 34 has a second groove. An intermediate element, separate from the transmission element 54 and the piston 34, is provided and arranged in the first and second grooves, connecting the transmission element 54 and the piston 34. This intermediate element is a thermally isolating compensating element by means of which the piston 34 is particularly advantageously thermally decoupled from the transmission element 54 and thus from the friction surfaces 18, 22, 30, and 44. The intermediate element is, for example, made of an elastomer and is designed, for example, as an O-ring, making it elastically deformable, particularly with rubber elasticity.For example, the inner diameter of the piston 34 at the location of the second groove is larger than the outer diameter of the transmission element 54 at that location by a radial offset that is the maximum permissible due to tolerances. To prevent excessive vibrations between the piston 34 and the transmission element 54, the intermediate element bridges a radial gap located at that point between the transmission element 54 and the piston 34. Furthermore, the intermediate element allows the piston 34 and the transmission element 54 to be joined together in a pre-assembly step.

[0060] The transmission element 54 has a projection extending axially from a base region of the transmission element 54 and away from the brake disc elements 16 and 20, in the outer circumferential surface of which the first groove is formed. The piston 34 has an inner circumferential surface radially facing the outer circumferential surface, which surrounds the outer circumferential surface and the first groove in the circumferential direction of the shaft 24 and thus the axle drive assembly 10. The second groove is formed in the inner circumferential surface. Furthermore, it is provided that a chamfer on the inner circumferential surface, widening axially towards the base region, adjoins the second groove at an end of the piston 34 that faces axially towards the base region.

[0061] By hydraulically actuating the piston 34, the piston 34 is axially displaceable and movable relative to the housing 12 and relative to the transmission element 54 in the direction of movement, and thus in the direction of the friction surfaces 18 and 22, under elastic deformation of the intermediate element. This allows an end face of the piston 34 to be displaced and thus moved into direct contact with a corresponding support surface of the transmission element 54. This means that, in an actuated state of the piston 34, the end face rests directly against the corresponding support surface, enabling a particularly advantageous force transmission between the piston 34 and the transmission element 54. The piston 34 can be moved from an unactuated state to an actuated state by hydraulically actuating the piston 34.In the actuated state of piston 34, the intermediate element is elastically deformed to a greater extent than in the unactuated state of piston 34, which occurs when the piston 34 is no longer supplied with hydraulic fluid. Thus, when the hydraulic actuation of piston 34 is terminated, at least partial elastic relaxation of the intermediate element is permitted, and this at least partial elastic relaxation of the intermediate element is also referred to as expansion.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, which is 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, to be axially displaced from the transmission element 54 and the support surface in a release direction opposite to the direction of movement. As a result, the end face is completely separated from the support surface in the unactuated state of the piston 34. Preferably, in the unactuated state of the piston 34, the piston 34 is completely separated from the transmission element 54, which is formed separately from the piston 34. This prevents undesirable, excessive heat transfer from the transmission element 54 to the piston 34.

[0062] 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 against the support surface and therefore 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, which is elastically deformed in the actuated state of the piston 34 and thereby at least or exclusively axially deformed, 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 and the support surface 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.

[0063] The brake assembly 14 has a spring element 85, which is designed as a solid body and thus as a mechanical spring element, i.e., a mechanical spring. The spring element 85 is 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. 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, 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 released or is released. This releases the brake assembly 14, which is also simply referred to 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, and 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, especially 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 amount. Even if the brake disc element 20 wears, the brake clearance remains at least essentially constant.

[0064] The intermediate element, which functions or is designed as a decoupling element, enables the simple and cost-effective connection of the piston 34, designed here as a ring brake piston, and the transmission element 54, designed here as a pressure plate, to form an assembly unit. During the joining process of the transmission element 54 to the piston 34, also referred to as joining, the intermediate element is radially compressed by means of the chamfer of the piston 34 until the intermediate element engages, or snaps into, the second groove of the piston 34, which is designed here as a detent groove. In the state of the intermediate element being positioned in the second groove, it is elastically deformed, particularly radially, and thus pre-stressed. For example, the first groove 78 is designed as an O-ring groove. The intermediate element, which is partially positioned in the grooves, 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 from the piston 34.

[0065] By introducing hydraulic fluid, for example oil, into the actuation chamber 52, a pressure, particularly oil pressure, increases 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, in the direction of movement and thus towards the transmission element 54. During this movement, the intermediate element is elastically deformed and compressed, so that its end face comes into direct contact with the support surface. 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 and the end face, and subsequently to the brake disc elements 16, 20, and 42.By ceasing the hydraulic actuation of piston 34, also known as releasing the brake, the pressure in the actuation chamber 52 drops again, causing piston 34 to move away from the transmission element 54. This allows the intermediate element to expand again. To ensure, for example, that the intermediate element expands not only radially but also axially, a shoulder, also referred to as a shoulder surface, is arranged in the first groove. This shoulder is formed, for example, by the groove base of the first groove. The shoulder is conical and thus follows an imaginary cone that widens axially, i.e., in the axial direction of the shaft 24 towards the friction surfaces 18 and 22. The shoulder ensures that when the intermediate element relaxes and thus expands, it is pushed away from the transmission element 54 or the support surface.Since the intermediate element is supported in the second groove 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 relaxes and thus expands, and by means of the intermediate element the piston 34 and the transmission element 54 can be advantageously thermally isolated from each other, i.e. decoupled.

[0066] Reference symbol list

[0067] 10 axle drive unit

[0068] 12 cases

[0069] 14 Brake system

[0070] 16 first brake disc element

[0071] 18 first friction surface

[0072] 20 second brake disc element

[0073] 22 second friction surface

[0074] 24 wave

[0075] 26 axis of rotation

[0076] 28 Double Arrow

[0077] 30 third friction surface

[0078] 32 Double Arrow

[0079] 34 pistons

[0080] 36 Double Arrow

[0081] Part 38

[0082] 40 joint

[0083] 42 third brake disc element

[0084] 44 fourth friction surface

[0085] 46 gear teeth

[0086] 48 teeth

[0087] 50 hydraulic channel

[0088] 52 Activity area

[0089] 54 Transmission element

[0090] 56 Cooling Structure

[0091] 58 Cooling Structure

[0092] 60 first housing part

[0093] 62 second housing part

[0094] 64 Case opening

[0095] 66 warehouses

[0096] 68 Recording room

[0097] 70 Interior

[0098] 72 surroundings

[0099] 74 third housing part

[0100] 76 Lid opening

[0101] 85 Spring element arrow

[0102] 90 Sealing element

[0103] 92 Sleeve

[0104] Level 94

[0105] 96 Effective area

[0106] TB sub-area

Claims

Mercedes-Benz Group AG Patent claims 1. Axle drive device (10) for a motor vehicle, comprising at least one integrated friction brake device (14) arranged in an interior space (68) of an intermediate cover (62) closing a transmission compartment (70), comprising an output shaft (24), and an end cover (74) with an outer circumferential conical ring shape at least in a partial area, which is arranged coaxially to the output shaft (24) rotatable relative to the end cover (74), extends along the output shaft (24) and closes the interior space (68) of the intermediate cover (62), and comprising an actuating piston (34) which can be actuated with hydraulic fluid for hydraulic actuation of the friction brake device (14) and is thereby movable in a direction of movement and directly delimits an actuating chamber (52) into which the hydraulic fluid can be introduced for actuating the actuating piston (34), wherein: - the actuation chamber (52) and the actuation piston (34) are arranged on an inner circumference of the end cover (74); and - the actuating piston (34) is designed as a ring piston, the direction of movement of which is in the axial direction of the output shaft (24).

2. Axle drive device (10) according to claim 1, characterized in that the output shaft (24) has a tripod joint (40).

3. Axle drive device (10) according to claim 2, characterized in that the tripod joint (40) is extended from the end cover (74) in the circumferential direction of the output shaft (24) is surrounded such that a central axis of the end cover (74) coincides with a central axis of the output shaft (24).

4. Axle drive device (10) according to claim 2 or 3, characterized in that a sealing element (90) is provided which is arranged in the radial direction of the output shaft (24) between a sleeve (92) which is rotatable with the output shaft (24) relative to the end cover (74) and which surrounds the tripod joint (40) in the circumferential direction of the output shaft (24) and the end cover (74), so that the end cover (74) is sealed against the sleeve (90) by means of the sealing element (90).

5. Axle drive device (10) according to one of the preceding claims, characterized in that the actuating piston (34) has a step (94) which forms an effective surface (96) of the actuating piston (34).

6. Motor vehicle, with an axle drive device (10) according to one of the preceding claims.

Images