Brake device for motor vehicle and electrically actuatable axle drive train

Abstract

The invention relates to a brake device (1) for an electrically operable axle drive train (2) of a motor vehicle (3). The brake device (1) is coupleable to a wheel (4) of a motor vehicle (3) such that actuation of the brake device (1) brakes the wheel (4), and the brake device (1) comprises a hydraulic disengagement system (5) comprising a central disengagement element (6) actuating a friction device (7) which is coupled to the wheel (4) of the motor vehicle (3) such that actuation of the brake device (1) brakes the wheel (4). The friction device can be converted into a braking operation state and a non-braking operation state. The central disengagement element (6) also has a central disengagement element housing (8) which comprises an annular central disengagement element piston chamber (9), the central disengagement element piston (11) is received in the central disengagement element piston chamber (9) in an axially displaceable manner by means of a hydraulic fluid (10) which can be supplied to the central disengagement element piston chamber (9), and wherein the central disengagement element (6) has at least one central disengagement element piston seal (12), the central disengagement element piston (11) has at least one central disengagement element piston seal which seals the central disengagement element piston (11) against the central disengagement element piston chamber (9), and the central disengagement element (6) and the friction device (7) are received in a brake housing (13) which is designed in two parts, the two parts comprise a pot-shaped first housing part (14) and a cover-shaped second housing part (15) which at least partially covers the pot-shaped first housing part (14). The pot-shaped first housing part (14) forms a central disconnect element housing (8) of the central disconnect element (6).

Description

Technical Field

[0001] The invention relates to a brake device for an electrically operable axle drive train of a motor vehicle, wherein the brake device can be coupled to a wheel of the motor vehicle so that actuation of the brake device brakes the wheel, wherein the brake device comprises a hydraulic disconnection system, the hydraulic disconnection system comprising a central disconnection element, the central disconnection element actuating a friction device so that the friction device can be switched into a braking operation state and a non-braking operation state, and the central disconnection element also has a central disconnection element housing, the central disconnection element housing comprising an annular central disconnection element piston chamber, in which the central disconnection element piston is received in a manner that it can be axially moved by a hydraulic fluid that can be supplied to the central disconnection element piston chamber, wherein the central disconnection element has at least one central disconnection element piston seal, the at least one central disconnection element piston seal sealing the central disconnection element piston relative to the central disconnection element piston chamber, and the central disconnection element and the friction device are received in the brake housing. The invention also relates to an electrically operable axle drive train of a motor vehicle. Background Art

[0002] Electric motors are increasingly being used to drive motor vehicles, creating an alternative to fossil fuel-intensive internal combustion engines. Considerable efforts have been made to improve the suitability of electric drives for everyday use and also to provide users with the driving comfort to which they are accustomed.

[0003] A detailed description of the electric drive can be found in an article by Erik Schneider, Frank Fickl, Bernd Cebulski and Jens Liebold published in the German automobile magazine ATZ, Vol. 113, May 2011, pages 360 to 365, entitled: Hochintegrativ und Flexibel Elektrische Antriebseinheit für E-Fahrzeuge [Highly Integrative and Flexible Electric Drive Unit for E-Vehicles]. The article describes a drive unit for an axle of a vehicle, which comprises an electric motor which is arranged concentrically and coaxially with respect to a bevel gear differential, wherein a switchable 2-speed planetary gear set is arranged in the drive train between the electric motor and the bevel gear differential and which is likewise positioned coaxially with the electric motor and the bevel gear differential or the spur gear differential. The drive unit is very compact and, due to the switchable 2-speed planetary gear set, allows a good compromise between gradeability, acceleration and energy consumption. Such a drive unit is also referred to as an electric axle or an electrically operable drive train.

[0004] There is a continuing need for an axle drive train that provides the driver or vehicle controller with a variety of different operating modes in order to provide the highest levels of energy efficiency, comfort and safety. Summary of the invention

[0005] The object of the present invention is therefore to provide a braking device for an electrically operable axle drive train of a motor vehicle, which has a structure that is as simple and cost-effective as possible. In addition, the object of the present invention is to achieve an electrically operable axle drive train for a motor vehicle, which axle drive train provides a plurality of different operating modes.

[0006] The object is achieved by a braking device for an electrically operable axle drive train of a motor vehicle, wherein the braking device can be coupled to a wheel of the motor vehicle so that actuation of the braking device brakes the wheel, wherein the braking device comprises a hydraulic disconnection system, the hydraulic disconnection system comprising a central disconnection element, the central disconnection element actuating a friction device so that the friction device can be switched into a braking operation state and a non-braking operation state, and the central disconnection element also has a central disconnection element housing, the central disconnection element housing comprising an annular central disconnection element piston chamber, the central disconnection element piston being able to be supplied to the central disconnection element by a hydraulic pressure that can be supplied to the central disconnection element The hydraulic fluid in the piston chamber of the central disconnect coupling element is received in the piston chamber of the central disconnect coupling element in an axially movable manner, wherein the central disconnect coupling element has at least one central disconnect coupling element piston seal, and the at least one central disconnect coupling element piston seal seals the central disconnect coupling element piston relative to the central disconnect coupling element piston chamber, and the central disconnect coupling element and the friction device are received in the brake housing, wherein the brake housing is designed as two parts, the two parts including a pot-shaped first housing part and a cover-shaped second housing part at least partially covering the pot-shaped first housing part, wherein the pot-shaped first housing part forms the central disconnect coupling element housing of the central disconnect coupling element.

[0007] This has the advantage that no separate central disconnecting element housing is required, which brings both cost advantages and assembly advantages. The pot-shaped housing part is preferably formed in one piece, so that it has no unnecessary sealing points and is therefore particularly suitable for wet-running friction devices, since appropriate sealing measures can be reduced to a minimum. In order to accommodate the central disconnecting element piston, the pot-shaped first housing part can, for example, have an annular circumferential groove, into which the central disconnecting element piston is guided in an axially displaceable manner.

[0008] In particular, the brake housing also prevents dust from the friction device from entering the environment, which helps to reduce the impact on the environment during operation of the brake device. In addition, the brake noise can be well suppressed by the housing.

[0009] The individual elements of the claimed subject matter of the invention will first be described in the order in which they are mentioned in the claims, after which particularly preferred embodiments of the subject matter of the invention will be described.

[0010] The central disconnecting and engaging element for actuating the brake device is preferably intended for use in a hydraulic disconnecting and engaging system. The hydraulic disconnecting and engaging system usually has an active cylinder, which transmits the pressure generated on the active cylinder to the slave cylinder, in this case to the central disconnecting and engaging element, via a hydraulic pressure line. In particular, the hydraulic pressure can also be provided by means of a power pack, which comprises a hydraulic pump and a hydraulic accumulator that can be acted upon by the hydraulic pump. In this case, the pressure chamber of the slave cylinder can also be hydraulically pressurized, for example by means of an electric motor, via the active cylinder controlled by the control unit or by a hydraulic pump optionally cooperating with a pressure accumulator. A power pack can be used in an advantageous manner, which in particular switches a plurality of pressure circuits via a central hydraulic pump and corresponding valves.

[0011] Therefore, the hydraulic disconnection system particularly preferably hydraulically actuates the friction device of the brake device by acting on the active cylinder.As explained, this can be achieved by means of an actuator controlled by a control unit or, for example, by manual actuation by the driver using a brake pedal.

[0012] The central disconnecting element can be used particularly preferably in a clutch system for a motor vehicle. The clutch system can have the following functions: to engage or disengage the drive side of a motor in a drive train of the vehicle in a shiftable manner and thus, for example, to be able to shift the transmission while driving and thus to be able to operate the drive motor in a preferred speed / torque range or to engage an electric motor or an internal combustion engine with the drive train or to engage an electric motor or an internal combustion engine into the drive train.

[0013] Within the meaning of the present application, a clutch system can also be a brake system in which at least a part of the torque-transmitting friction device is designed to be non-rotatable.

[0014] For the purposes of this application, a motor vehicle is a land vehicle that moves by machine power and is not constrained by railway tracks. The motor vehicle may for example be selected from the group of: a passenger car, a truck, a scooter, a light motor vehicle, a motorcycle, a bus / coach or a tractor.

[0015] The central disconnect coupling element according to the present invention has a central disconnect coupling element housing. The central disconnect coupling element housing has the function of receiving the various components of the central disconnect coupling element, in particular receiving the moving central disconnect coupling element piston and protecting these components from external mechanical or chemical influences. In addition, the central disconnect coupling element housing has the function of allowing simple assembly and fixation of the central disconnect coupling element in the transmission system. The central disconnect coupling element housing can be made into a one-piece or multi-piece type. The central disconnect coupling element housing can preferably be formed of plastic, metal material and / or ceramic material. The central disconnect coupling element piston chamber formed in the central disconnect coupling element housing is used to receive and guide the central disconnect coupling element piston, which is installed in the central disconnect coupling element housing in a linearly movable manner.

[0016] Preferably, the central breaking engagement element housing is formed integrally, in particular monolithically, with the pot-shaped first housing part.

[0017] The central disconnecting element also has a central disconnecting element piston. The central disconnecting element piston has the function of converting hydraulic pressure into a linear displacement of the central disconnecting element piston, wherein the effect of this function is that the clutch system can be converted from an engaged operating state into a disengaged operating state. The central disconnecting element can have an annular central disconnecting element piston or several central disconnecting element pistons (multi-piston disconnecting element).

[0018] In addition, the central disconnection element has at least one central disconnection element piston seal. The central disconnection element piston seal seals the central disconnection element piston guided for linear movement against the central disconnection element housing that receives the central disconnection element piston. The central disconnection element piston seal can be designed in particular as a sealing ring. It is particularly preferred that the central disconnection element piston seal is formed by an elastic material, particularly preferably a rubber-elastic material. The elastic material can preferably be composed entirely or partially of an elastomer, wherein the elastomer is preferably selected from the group of natural rubber vulcanizates and silicone rubber.

[0019] In hydraulic disconnect and engagement systems of motor vehicles, hydraulic fluids have the function of transferring energy in the form of pressure with as little loss as possible, for example within the brake system and / or clutch system of the vehicle. In addition to this primary purpose, the hydraulic fluids can also provide lubrication and corrosion protection, in particular, for moving parts and metal surfaces of the hydraulic disconnect and engagement system. In addition, the hydraulic fluids can also, in particular, remove impurities (for example due to wear), water and air, as well as waste heat.

[0020] According to another particularly preferred embodiment of the present invention, it can be provided that the central disconnection coupling element piston and / or the central disconnection coupling element housing are formed from plastic. This has the particular effect that the central disconnection coupling element can be manufactured in a cost-effective manner and is particularly designed to be weight-optimized.

[0021] Advantageous embodiments of the invention are specified in the dependent claims. The features listed individually in the dependent claims can be combined with one another in a technically meaningful manner and can define further embodiments of the invention. In addition, the features indicated in the claims are described and explained in more detail in the description, wherein further preferred embodiments of the invention are shown.

[0022] According to an advantageous embodiment of the invention, it can be provided that the brake housing has a shaft passing through it, which shaft is connected to the friction device of the brake device in a torque-transmitting manner, wherein the shaft is mounted relative to the pot-shaped first housing part by means of a first rolling bearing, and a first bearing seat of the first rolling bearing is formed on the pot-shaped first housing part. This design has the advantage that the system integration on the first housing part can also be further increased by providing the first housing part with a bearing seat for the first rolling bearing in addition to the central disconnect coupling element.

[0023] According to another further preferred improvement of the present invention, it can also be arranged that the shaft is mounted relative to the pot-shaped first housing part by means of a second rolling bearing, and the second bearing seat of the second rolling bearing is formed on the cover-shaped second housing part, which also helps to improve the system into the braking device.

[0024] Furthermore, according to an equally advantageous embodiment of the invention, it can be provided that the cover-shaped second housing part is formed by the motor housing of the electric machine. The advantageous effect of this embodiment is based on the fact that the provision of a separate cover for closing the pot-shaped first housing part can be omitted, which can also contribute to a cost-effective design of the brake device.

[0025] According to another particularly preferred embodiment of the present invention, it can be provided that the pot-shaped first housing part is formed from a metal sheet. This has the particular effect that the first housing part can be reshaped, which is particularly advantageous in terms of manufacturing technology.

[0026] Furthermore, the invention can be further developed in such a way that the friction device is designed as a multi-disk brake, in which a particularly advantageous braking effect of the brake device can be achieved.

[0027] The function of a multi-disc brake is to establish a releasable force-fit connection between the clutch input shaft and the clutch output shaft to support torque. The alternating inner and outer disks of the disk pack can be brought into force-fit or friction contact by axial displacement and compression of the corresponding friction linings of the inner and outer disks by means of the clutch engagement process, so that the inner disks rotate relative to the outer disks in a frictional manner around the common rotation axis of the corresponding disk pack, or are arranged so that the inner and outer disks cannot rotate relative to each other in the case of full friction engagement.

[0028] On the other hand, if the inner and outer plates are pushed axially away from each other by the disengagement process, there is no longer any force-fitting contact between the inner and outer plates, so that the inner and outer plates can rotate freely against each other, and therefore no rotation or braking torque is transmitted between the inner and outer plates.

[0029] In a possible design of such a multi-disc brake, the clutch input shaft can be connected torsionally rigidly to the outer disk carrier of the multi-disc clutch. All outer disks are then freely guided in the axial direction by means of the inner toothing of the outer disk carrier. The inner disks, which are also freely guided in the axial direction by the toothing of the inner disk carrier, are then arranged alternately between the outer disks. This means that all inner disks are connected torsionally rigidly to the clutch output shaft. When the multi-disc clutch is closed by actuating the central disconnecting engagement element, friction occurs between the outer and inner disks. The friction forces thus generated cause a force flow from the outer disk carrier to the inner disk carrier, which enables the torque to be transmitted from the clutch input shaft to the clutch output shaft. When the central disconnecting engagement element is not actuated, the inner and outer disks are separated, depending on the design, by the action of springs or, in the case of a wet-running multi-disc brake, by the flow of oil between the disks.

[0030] In connection with the present invention, the function of the multi-disc brake is to establish a releasable force-fit connection between the clutch input shaft and the clutch output shaft in order to support a rotational or braking torque.

[0031] A multi-disc brake generally comprises at least two inner disks and / or two outer disks. The inner disks are preferably arranged in a rotationally fixed manner on an inner disk carrier and the outer disks are preferably arranged in a rotationally fixed manner on an outer disk carrier. The inner disk carrier is in particular connected to the clutch output shaft and the outer disk carrier is in particular connected to the clutch input shaft, or the inner disk carrier is in particular connected to the clutch input shaft and the outer disk carrier is in particular connected to the clutch output shaft.

[0032] The inner and outer disks form a disk pack of a multi-disc brake. In the disk pack, a plurality of inner and outer disks are preferably arranged alternately with each other in the axial direction. The rotational or braking torque that can be transmitted between the inner and outer disks by the multi-disc brake can be adjusted by the number and design of the inner and outer disks.

[0033] The inner disk has the function of transmitting the torque from the outer disk to the inner disk carrier, in particular in a force-fitting or frictional manner. The inner disk can be designed in particular as a circular disk. The inner disk can be connected to the inner disk carrier of the multi-disk brake in a rotationally fixed manner. It can also be provided that the inner disk can be displaced in the axial direction relative to the inner disk carrier, for example by means of a corresponding toothing, in order to establish a frictional engagement with the outer disk.

[0034] The outer disk has the function of transmitting the torque from the inner disk to the outer disk carrier, in particular in a force-fitting or frictional manner. The outer disk can be designed in particular as a circular disk. The outer disk can be connected to the outer disk carrier of the multi-disk clutch in a rotationally fixed manner. It can also be provided that the outer disk can be displaced in the axial direction relative to the outer disk carrier, for example by means of corresponding toothing, in order to establish a frictional engagement with the inner disk. The outer disk carrier can be designed, for example, as an outer disk clutch cage.

[0035] The multi-disc brake may preferably comprise a spring. The spring has the task of moving the inner and outer discs into a predetermined position relative to each other using a spring force. Typically, this predetermined position corresponds to a "normally open" or "normally closed" operating state of the multi-disc brake, which means that when the central disconnect coupling element is not actuated, the inner and outer discs are pressed against each other by the spring or are released.

[0036] The multi-disc brake is operated via a central disengaging element. The central disengaging element has the function of enabling a braking process of the multi-disc brake. The braking process can in particular be an engagement and / or disengagement of the multi-disc brake. Since sometimes great forces may be required to engage or disengage the multi-disc brake, it can in particular be provided that the central disengaging element can be actuated by means of a hydraulic power assist.

[0037] Furthermore, the multi-disk brake may also have a switching piston which has the function of converting the engagement and disengagement processes determined by the central disengagement element into an axial displacement of the inner and / or outer disks in order to establish the frictional engagement when the multi-disk brake is engaged or to release the frictional engagement when the multi-disk brake is disengaged.

[0038] According to an advantageous embodiment of the present invention, it can be provided that the inner disk and / or the outer disk are designed as steel disks. According to another further preferred improvement of the present invention, it can also be provided that the inner disk and / or the outer disk have splines.

[0039] Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the inner disk is received in the inner disk carrier and / or the outer disk is received in the outer disk carrier.

[0040] In an equally preferred embodiment of the present invention, it can also be provided that the shaft has an axially extending first fluid channel and a second fluid channel branching from the first fluid channel and extending radially outward through the shaft, and the cooling fluid for cooling the friction device can enter the braking device at the outlet of the second fluid channel, wherein the pot-shaped first housing part has a first connecting opening for the cooling fluid to enter the first fluid channel of the shaft, and a second connecting opening for the cooling fluid to leave the braking device is also provided.

[0041] This means that the brake device can be cooled effectively. In addition, it is possible to design a brake device with a wet-running friction device. The dissipated heat can then be used within the vehicle, for example for temperature control in the passenger compartment.

[0042] The object of the present invention is also achieved by an electrically operable axle drive system of a motor vehicle, which includes: an electric motor having a stator and a rotor that can rotate relative to the stator to drive at least one wheel of the motor vehicle; and a braking device that can be connected to the wheel of the motor vehicle so that actuation of the braking device brakes the wheel, wherein the braking device is designed according to one of claims 1 to 7.

[0043] According to another preferred embodiment of the subject matter of the invention, it can be provided that the rotor of the electric machine and the shaft of the brake device extend coaxially to each other. Finally, the invention can also advantageously be designed such that the rotor of the electric machine is permanently connected to the shaft of the brake device in a torque-transmitting manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The invention is explained in more detail below with reference to the accompanying drawings without limiting the general concept of the invention.

[0045] In the attached picture:

[0046] Figure 1 A motor vehicle with an electric axle drive train and a brake device is shown in a schematic block diagram,

[0047] Figure 2 A schematic block diagram shows an axle drive train with a brake device.

[0048] Figure 3 The brake device is shown in an axial cross-section,

[0049] Figure 4 A detailed view of the central break-engagement element is shown in axial section. DETAILED DESCRIPTION

[0050] Figure 1A brake device 1 is shown in an electrically operable axle drive train 2 of a motor vehicle 3 , wherein the brake device 1 can be coupled to wheels 4 of the motor vehicle 3 , such that an actuation of the brake device 1 brakes the wheels 4 .

[0051] For this purpose, it can be Figure 2 As seen in FIG. 1 , the brake device 1 has a hydraulic disconnection system 5 comprising a central disconnection element 6 which actuates a friction device 7 so that it can be switched into a braking operation state and a non-braking operation state.

[0052] The central disconnecting element 6 has a central disconnecting element housing 8, which includes an annular central disconnecting element piston chamber 9, in which a central disconnecting element piston 11 is received in such a way that it can be axially moved by a hydraulic fluid 10 that can be supplied to the central disconnecting element piston chamber 9, wherein the central disconnecting element 6 has at least one central disconnecting element piston seal 12, which seals the central disconnecting element piston 11 relative to the central disconnecting element piston chamber 9, which is Figure 3 Clearly illustrated in the figure.

[0053] The central disconnecting engagement element 6 and the friction device 7 are accommodated in a brake housing 13, wherein the brake housing 13 is designed in two parts, comprising a pot-shaped first housing part 14 and a cover-shaped second housing part 15 which at least partially covers the pot-shaped first housing part 15. Figures 2 to 3 As shown in FIG. 1 , the cover-shaped second housing part 15 is formed by the motor housing 19 of the electric motor 20 . The pot-shaped first housing part 14 is formed from sheet metal and forms the central disconnecting coupling element housing 8 of the central disconnecting coupling element 6 .

[0054] The central disconnecting element piston chamber 9 of the central disconnecting element 6 is integrated into a one-piece pot-shaped first housing part 14 of the brake device 1. The first housing part 14 thus forms the central disconnecting element housing 8. The central disconnecting element piston chamber 9 is designed as a coaxial ring, in which the central disconnecting element piston 11 can be axially displaced. A plurality of through holes are arranged on the outer diameter of the pot-shaped first housing part 14, through which the first housing part 14 is connected to the cover-shaped second housing part 15 of the motor 20 by means of fastening screws 31. The fastening screws 31 absorb the axial forces acting during operation and transmit them to the second housing part 15 of the motor 20. An O-ring groove with a seal 32 is arranged in the second housing part 15 of the motor 20 near the fastening screws 31. This serves to seal the wet chamber of the brake device 1 relative to the environment.

[0055] The disk pack of the multi-disk brake is axially positioned and supported in the direction of the electric machine 20 by means of a cylindrical dome 42 which is integrated in the second housing part 15 of the electric machine 20. The outer surface of the cylindrical dome 42 supports the torque acting during operation via a counter-geometry arranged in the outer disk carrier 38 and transmits this torque to the second housing part of the electric drive machine 20. The outer disk carrier 38 is connected to the second housing part 15 of the electric machine 20 via fastening screws 33 and is axially fixed.

[0056] The brake housing 13 has a shaft 16 passing through the brake housing, which is connected to the friction device 7 of the brake device 1 in a torque-transmitting manner, wherein the shaft 16 is mounted relative to the pot-shaped first housing part 14 by means of a first rolling bearing 17, and a first bearing seat 18 of the first rolling bearing 17 is formed on the pot-shaped first housing part 14. In addition, the shaft 16 is mounted relative to the pot-shaped first housing part 14 by means of a second rolling bearing 21, and a second bearing seat 22 of the second rolling bearing 21 is correspondingly formed on the cover-shaped second housing part 15. The rotor 30 of the motor 20 and the shaft 16 of the brake device 1 extend coaxially with each other and the rotor 30 of the motor 20 is permanently connected to the shaft 16 of the brake device 1 in a torque-transmitting manner.

[0057] Figure 3 Also shown is a friction device 7 designed as a multi-disc brake. Figure 3 It can be seen that the shaft 16 has a first fluid channel 23 extending coaxially and a second fluid channel 24 branching from the first fluid channel and extending radially outward through the shaft 16, at the outlet 25 of which a cooling fluid 26 for cooling the friction device 7 can enter the brake device 1, wherein the pot-shaped first housing part 14 has a first connecting opening 27 for the cooling fluid 26 to enter the first fluid channel 23 of the shaft 16, and a second connecting opening 28 is also provided for the cooling fluid 26 to leave the brake device 1. This enables the fluid between the cooling fluid lines 40 to be transferred via the fluid channels 23, 24 to the inner diameter of the inner disk carrier 37. Bores are arranged in the inner disk carrier 37, through which the cooling fluid 26 can reach the disk pack of the multi-disk brake. The cooling fluid 26 reaches the inner wall of the pot-shaped first housing part 14 via the bores arranged in the outer disk carrier 38. From the inner wall, the cooling fluid 26 reaches the line 41, through which the cooling fluid 26 is discharged from the brake housing 13.

[0058] The shaft 16 of the brake device 1 is connected to the rotor shaft 34 of the motor 20 via a toothing 35 so that both speed and torque can be transmitted. The bearing of the shaft 16 of the brake device 1 is arranged in the motor housing 19 of the motor 20. In addition, a sliding belt 36 is arranged in the same component.

[0059] Figure 4 The reset mechanism of the central disconnecting element 6 is shown in detail. A support plate 45 for a preload spring 44 is arranged on the axially fixed and non-rotating outer disc carrier 38. A dome for locating the inner diameter of the preload spring 44 designed as a helical spring is arranged in the support plate 45. A cylindrical receiving part 43 for the preload spring 44 is arranged in the central disconnecting element piston 11. The geometry of the central disconnecting element piston 11 pressing on the disc pack of the multi-disc brake is interrupted in the area of ​​the cylindrical receiving part 43. The distance between the support plate 45, the preload spring 44 and the upper edge of the central disconnecting element piston 11 defines the maximum disconnecting stroke of the central disconnecting element piston 11. When actuated, in addition to the axial force required to generate the braking torque, the axial force required to overcome the spring force of the preload spring 44 must also be applied. If no axial force is required to generate the braking torque, the preload spring 44 pushes the central disconnecting element piston 11 away from the disc pack. In this case, a stop is integrated into the central disconnecting element piston 11 , which stop contacts the first housing part 14 at a defined distance and thus limits the maximum distance of the central disconnecting element piston 11 relative to the disc pack.

[0060] The terms "radial", "axial", "tangential" and "circumferential direction" used in this application always refer to the axis of rotation of the shaft of the braking device. The terms "left", "right", "above", "below", "above" and "below" are used here only to clarify the area of ​​the illustration currently described in the text. Later embodiments of the present invention may also be arranged in different ways. The present invention is also not limited to the embodiments shown in the accompanying drawings. Therefore, the above description should not be regarded as restrictive, but as illustrative. The attached claims should be understood to mean that the stated features are present in at least one embodiment of the present invention. This does not exclude the presence of other features. In the case where the claims and the above description define a "first" feature and a "second" feature, this naming is used to distinguish between two features of the same type without limiting the order of priority.

[0061] Reference numerals list

[0062] 1 Braking device

[0063] 2 Axle drive train

[0064] 3 Motor vehicles

[0065] 4 wheels

[0066] 5 Disconnect the engagement system

[0067] 6 Central disconnect coupling element

[0068] 7 Friction device

[0069] 8 Central disconnect coupling element housing

[0070] 9 Central disconnection engagement element piston chamber

[0071] 10 Hydraulic fluid

[0072] 11 Central disconnect element piston

[0073] 12 Central disconnection engagement element piston seal

[0074] 13 Brake housing

[0075] 14 Shell part

[0076] 15 Shell part

[0077] 16 Axis

[0078] 17 Rolling bearings

[0079] 18 Bearing seat

[0080] 19 Motor housing

[0081] 20 Motor

[0082] 21 Rolling bearings

[0083] 22 Bearing seat

[0084] 23 Fluid Channel

[0085] 24 Fluid Channels

[0086] 25 Exit

[0087] 26 Cooling fluid

[0088] 27 Connection opening

[0089] 28 Connection opening

[0090] 29 Stator

[0091] 30 Rotor

[0092] 31 Fastening screw

[0093] 32 Seals

[0094] 33 Fastening screw

[0095] 34 Rotor shaft

[0096] 35 teeth

[0097] 36 Slide belt

[0098] 37 Inner plate carrier

[0099] 38 outer disc carrier

[0100] 39 Pressure lines

[0101] 40 Cooling fluid lines

[0102] 41 Cooling fluid lines

[0103] 42 Barrel Dome

[0104] 43 Reception Department

[0105] 44 Preload Spring

[0106] 45 Support plate.

Claims

1. A braking device (1) for an electrically operable axle drive train (2) of a motor vehicle (3), wherein: The brake device (1) can be coupled to a wheel (4) of the motor vehicle (3) such that actuation of the brake device (1) brakes the wheel (4), wherein: The brake device (1) comprises a hydraulic disconnection and engagement system (5), the hydraulic disconnection and engagement system comprising a central disconnection and engagement element (6), the central disconnection and engagement element actuating a friction device (7) so that the friction device can be switched into a braking operation state and a non-braking operation state, and the central disconnection and engagement element (6) also has a central disconnection and engagement element housing (8), the central disconnection and engagement element housing comprising an annular central disconnection and engagement element piston chamber (9), a central disconnection and engagement element piston (11) being received in the central disconnection and engagement element piston chamber in a manner capable of axial movement by a hydraulic fluid (10) that can be supplied to the central disconnection and engagement element piston chamber (9), wherein the central disconnection and engagement element (6) has at least one central disconnection and engagement element piston seal (12), the at least one central disconnection and engagement element piston seal sealing the central disconnection and engagement element piston (11) relative to the central disconnection and engagement element piston chamber (9), and The central disconnecting engagement element (6) and the friction device (7) are received in a brake housing (13), It is characterized in that The brake housing (13) is designed in two parts, comprising a pot-shaped first housing part (14) and a cover-shaped second housing part (15) which at least partially covers the pot-shaped first housing part (15). The pot-shaped first housing part (14) forms the central disconnecting element housing (8) of the central disconnecting element (6).

2. The braking device (1) according to claim 1, It is characterized in that The brake housing (13) has a shaft (16) passing through the brake housing, which is connected to the friction device (7) of the brake device (1) in a torque-transmitting manner, wherein the shaft (16) is mounted relative to the pot-shaped first housing part (14) by means of a first rolling bearing (17), and a first bearing seat (18) of the first rolling bearing (17) is formed on the pot-shaped first housing part (14).

3. The braking device (1) according to claim 1 or 2, It is characterized in that The shaft (16) is mounted relative to the pot-shaped first housing part (14) by means of a second rolling bearing (21), and a second bearing seat (22) of the second rolling bearing (21) is formed on the cover-shaped second housing part (15).

4. Braking device (1) according to one of the preceding claims, It is characterized in that The cover-shaped second housing part (15) is formed by a motor housing (19) of an electric motor (20).

5. Braking device (1) according to one of the preceding claims, It is characterized in that The pot-shaped first housing part (14) is formed from a metal sheet.

6. Braking device (1) according to one of the preceding claims, It is characterized in that The friction device (7) is designed as a multi-disc brake.

7. Braking device (1) according to one of the preceding claims, It is characterized in that The shaft (16) has an axially extending first fluid channel (23) and a second fluid channel (24) branching from the first fluid channel and extending radially outward through the shaft (16), and a cooling fluid (26) for cooling the friction device (7) can enter the brake device (1) at an outlet (25) of the second fluid channel, wherein the pot-shaped first housing part (14) has a first connecting opening (27) for the cooling fluid (26) to enter the first fluid channel (23) of the shaft (16), and a second connecting opening (28) is also provided for the cooling fluid (26) to leave the brake device (1).

8. An electrically operable axle drive train (2) of a motor vehicle (3), the axle drive train comprising: an electric motor (20) having a stator (29) and a rotor (30) rotatable relative to the stator for driving at least one wheel (4) of the motor vehicle (3); and a braking device (1) connectable to the wheel (4) of the motor vehicle (3) such that actuation of the braking device (1) brakes the wheel (4), It is characterized in that The braking device (1) is designed according to one of the preceding claims.

9. The axle drive train (2) according to claim 8, It is characterized in that The rotor (30) of the electric motor (20) and the shaft (16) of the brake device (1) extend coaxially relative to each other.

10. Axle drive train (2) according to claim 8 or 9, It is characterized in that The rotor (30) of the electric motor (20) is permanently connected to the shaft (16) of the brake device (1) in a torque-transmitting manner.

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