Braking device and electrically operated axle drive train of a motor vehicle

Abstract

Braking device (1) for an electrically operated axle drive train (2) of a motor vehicle (3), wherein the braking device (1) can be coupled to a vehicle wheel (4) of the motor vehicle (3) in such a way that actuation of the braking device (1) causes the vehicle wheel (4) to brake, wherein The brake device (1) comprises a hydraulic release system (5) with a central release bearing (6) which actuates a friction device (7) in such a way that the latter can be switched between a braking and a non-braking operating state, and the central release bearing (6) further comprises a central release bearing housing (8) with an annular central release bearing piston chamber (9) in which a central release bearing piston (11) is axially movably received by means of a hydraulic fluid (10) which can be supplied to the central release bearing piston chamber (9), wherein the central release bearing (6) has at least one central release bearing piston seal (12) which seals the central release bearing piston (11) against the central release bearing piston chamber (9), and the central release bearing (6) and the friction device (7) are received 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 second lid-shaped second housing part (15) which covers the first pot-shaped housing part (15) at least partially, wherein the first pot-shaped housing part (14) forms the central release housing (8) of the central release (6). characterized by the fact that the brake housing (13) is penetrated by a shaft (16) which is connected to the friction device (7) of the brake device (1) in a torque-transmitting manner, wherein the shaft (16) is supported relative to the cup-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 first cup-shaped housing part (14), and that the shaft (16) is supported 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 second lid-shaped housing part (15).

Description

[0001] The present invention relates to a braking device for an electrically operated axle drive train of a motor vehicle, wherein the braking device can be coupled to a vehicle wheel of the motor vehicle in such a way that actuation of the braking device causes the vehicle wheel to brake, wherein the braking device comprises a hydraulic release system with a central release bearing which actuates a friction device in such a way that the friction device can be switched between a braking and a non-braking operating state, and wherein the central release bearing further comprises a central release bearing housing with an annular central release bearing piston chamber in which a central release bearing piston is axially movably received by means of a hydraulic fluid which can be supplied to the central release bearing piston chamber, wherein the central release bearing has at least one central release bearing piston seal which seals the central release bearing piston against the central release bearing piston chamber.and the central release bearing and the friction device are housed in a brake housing. The invention further relates to an electrically operated axle drive train of a motor vehicle. Electric motors are increasingly being used in motor vehicles to provide alternatives to combustion engines that require fossil fuels. Considerable efforts have already been made to improve the everyday usability of electric drives and to offer users the familiar driving comfort.

[0002] A detailed description of an electric drive system can be found in an article in the journal ATZ, Volume 113, 05 / 2011, pages 360-365, by Erik Schneider, Frank Fickl, Bernd Cebulski, and Jens Liebold, entitled: "Highly Integrated and Flexible Electric Drive Unit for E-Vehicles." This article describes a drive unit for one axle of a vehicle, comprising an electric motor arranged concentrically and coaxially to a bevel gear differential. A switchable two-speed planetary gear set is located in the powertrain between the electric motor and the bevel gear differential, also positioned coaxially to the electric motor and the bevel or spur gear differential. The drive unit has a very compact design and, thanks to the switchable two-speed planetary gear set, allows for a good compromise between climbing ability, acceleration, and energy consumption.Such drive units are also referred to as e-axles or electrically operated drive trains.

[0003] With such axle drive trains, there is a continuing need to provide a variety of different operating modes for the driver or vehicle control system in order to offer maximum energy efficiency, comfort, and safety. A braking device according to the preamble of claim 1 is disclosed in US 2005 / 0279605 A1. Further prior art is disclosed in US 6415901 B1 and DE 102016105112 A1.

[0004] It is therefore an object of the invention to provide a braking device for an electrically operated axle drive train of a motor vehicle, which has the simplest and most cost-effective design possible. It is further an object of the invention to realize an electrically operated axle drive train for a motor vehicle that offers a variety of different operating modes.

[0005] This problem is solved by a braking device for an electrically operated axle drive train of a motor vehicle, wherein the braking device can be coupled to a vehicle wheel of the motor vehicle in such a way that actuation of the braking device causes the vehicle wheel to brake, wherein the braking device comprises a hydraulic release system with a central release bearing which actuates a friction device in such a way that it can be switched between a braking and a non-braking operating state, and wherein the central release bearing further comprises a central release bearing housing with an annular central release bearing piston chamber in which a central release bearing piston is axially movably received by means of a hydraulic fluid which can be supplied to the central release bearing piston chamber, wherein the central release bearing has at least one central release bearing piston seal which seals the central release bearing piston against the central release bearing piston chamber.and the central release bearing and the friction device are housed in a brake housing, the brake housing being designed in two parts, comprising a cup-shaped first housing part and a second lid-shaped second housing part, which covers the first cup-shaped housing part at least partially, the first cup-shaped housing part forming the central release bearing housing of the central release bearing.

[0006] This design offers the advantage of eliminating the need for a separate central release bearing housing, resulting in both cost and assembly benefits. The cup-shaped housing section is preferably molded in one piece, thus eliminating unnecessary sealing points and making it particularly suitable for wet friction systems, as the required sealing measures can be minimized. To accommodate the central release bearing piston, the first cup-shaped housing section can, for example, feature an annular groove in which the piston is guided for axial displacement.

[0007] The brake housing also prevents abrasion from the friction device from entering the environment, thus contributing to reduced environmental impact during brake operation. Furthermore, the housing effectively dampens brake noise.

[0008] First, the individual elements of the claimed subject matter of the invention are explained in the order in which they are mentioned in the claim set, and subsequently, particularly preferred embodiments of the subject matter of the invention are described.

[0009] The central release bearing for actuating the brake device is preferably designed for use in a hydraulic release system. A hydraulic release system typically has a master cylinder that transmits the pressure generated at the master cylinder to the slave cylinder, in this case a central release bearing, via a hydraulic pressure line. The hydraulic pressure can also be provided, in particular, by means of a so-called power pack, which consists of a hydraulic pump and a hydraulic pressure accumulator that can be pressurized by the hydraulic pump. In this case, a pressure chamber of the slave cylinder can also be hydraulically pressurized, for example, by a master cylinder controlled by an electric motor via a control unit, or by a hydraulic pump, optionally with the assistance of a pressure accumulator.Advantageously, a so-called powerpack can be used, which switches several pressure circuits via a central hydraulic pump and corresponding valves.

[0010] The hydraulic release system thus preferably actuates a friction device of a brake system hydraulically by applying pressure to the master cylinder. As explained, this can be done either by means of an actuator controlled by a control unit or, for example, by manual actuation by the driver using a brake pedal.

[0011] The central release bearing is particularly advantageous for use in a clutch system for motor vehicles. The clutch system can function to engage and disengage the driving engine side of a vehicle's drivetrain from the transmission side, thus enabling, for example, gear changes while driving and allowing the driving engine to operate within a preferred speed / torque range, or to engage and disengage an electric motor or an internal combustion engine from a drivetrain.

[0012] A clutch system within the meaning of this application can also be a brake system, in which case at least part of the torque-transmitting friction device is designed to be rotationally fixed.

[0013] For the purposes of this application, motor vehicles are defined as land vehicles that are moved by mechanical power and are not bound to railway tracks. A motor vehicle may be selected, for example, from the groups of passenger cars, trucks, mopeds, light vehicles, motorcycles, buses, or tractors.

[0014] A central release bearing has a central release bearing housing. The central release bearing housing serves to house components of the central release bearing, particularly the movable central release bearing piston, and to protect them from external mechanical or chemical influences. Furthermore, the central release bearing housing facilitates easy installation and securing of the central release bearing within the drivetrain. The central release bearing housing can be constructed from a single piece or multiple pieces. Preferably, the central release bearing housing can be made of a plastic, a metallic material, and / or a ceramic material. The central release bearing piston chamber formed within the central release bearing housing serves to accommodate and guide the central release bearing piston, which is mounted to move linearly within the housing.

[0015] Preferably, the central release housing is formed in one piece, in particular monolithically, with the first pot-shaped housing part.

[0016] The central release bearing also has a central release piston. The function of the central release piston is to convert hydraulic pressure into a linear displacement of the piston, thereby enabling the clutch system to be moved from an engaged to a disengaged operating state. The central release bearing can have one annular central release piston or multiple central release pistons (multi-piston release bearing).

[0017] Furthermore, the central release bearing has at least one central release bearing piston seal. The central release bearing piston seal seals the linearly guided central release bearing piston against the central release bearing housing that accommodates the central release bearing piston. The central release bearing piston seal can, in particular, be designed as a sealing ring. It is especially preferred that the central release bearing piston seal is made of an elastic, and preferably rubber-elastic, material. The elastic material can preferably consist entirely or partially of an elastomer, wherein the elastomers are preferably selected from the group of vulcanizates of natural rubber and silicone rubber.

[0018] In a motor vehicle's hydraulic release system, the hydraulic fluid's function is to transfer energy in the form of pressure with minimal loss, for example, within the vehicle's brake and / or clutch system. In addition to this primary function, the hydraulic fluid also provides lubrication and corrosion protection for the moving parts and metal surfaces of the hydraulic release system. Furthermore, it can dissipate contaminants (such as those from abrasion), water, air, and waste heat.

[0019] According to a further particularly preferred embodiment of the invention, the central release piston and / or the central release housing may be made of a plastic. This makes it possible, in particular, to achieve the effect that the central release can be manufactured cost-effectively and designed with a particularly optimized weight.

[0020] Advantageous embodiments of the invention are specified in the dependent claims. The features listed individually in the dependent claims can be combined in a technologically meaningful manner and can define further embodiments of the invention. Furthermore, the features specified in the claims are specified and explained in more detail in the description, which also presents further preferred embodiments of the invention.

[0021] According to the invention, the brake housing is penetrated by a shaft which is connected to the friction device of the brake assembly in a torque-transmitting manner. The shaft is supported relative to the cup-shaped first housing part by means of a first rolling bearing, and a first bearing seat for the first rolling bearing is formed on the first cup-shaped housing part. The advantage of this design is that the degree of system integration at the first housing part can be further increased by providing a bearing seat for a first rolling bearing in addition to the central release bearing.

[0022] According to a further preferred development of the invention, it can also be provided that the shaft is supported relative to the pot-shaped first housing part by means of a second rolling bearing, and a second bearing seat of the second rolling bearing is formed on the second lid-shaped housing part, which also contributes to improved system integration in the brake device.

[0023] Furthermore, according to another advantageous embodiment of the invention, the lid-like second housing part can be formed by the motor housing of an electric machine. The advantage of this embodiment is that it eliminates the need for a separate lid to close the first, pot-shaped housing part, which can also contribute to a more cost-effective design of the braking device.

[0024] According to a further particularly preferred embodiment of the invention, the first, pot-shaped housing part can be formed from a sheet metal part. This makes it possible, in particular, to achieve the effect that the first housing part can be reshaped, which is especially advantageous from a manufacturing perspective.

[0025] Furthermore, the invention can also be further developed in such a way that the friction device is designed as a lamellar brake, which makes it possible to achieve a particularly favorable braking effect of the braking device.

[0026] A multi-plate brake functions to create a releasable, friction-fit connection between a clutch input shaft and a clutch output shaft to support a torque. The alternating inner and outer plates of the disc pack can be brought into friction-fit or friction-fit contact by axial displacement and compression via their respective friction linings during an engagement process. This allows the inner plates to rotate relative to the outer plates around the common axis of rotation of the respective disc pack, or, in the case of complete frictional engagement, to be fixed against each other.

[0027] If, however, the inner and outer lamellae are pushed axially away from each other by a disengagement process, there is no longer any force-fit contact between the inner and outer lamellae, so that they can rotate freely against each other and consequently no rotational or braking torque is transmitted between the inner and outer lamellae.

[0028] In one possible embodiment of such a multi-plate clutch, the clutch input shaft can be rigidly connected to the outer plate carrier of the clutch. An internal toothing on the outer plate carrier then guides all outer plates for axial movement. The inner plates, also guided for axial movement by the toothing on the inner plate carrier, are arranged alternately between the outer plates. This rigidly connects all inner plates to the clutch output shaft. When the multi-plate clutch is engaged by actuating the central release bearing, friction is generated between the outer and inner plates. The resulting frictional forces transmit power from the outer plate carrier to the inner plate carrier, enabling torque transmission from the clutch input shaft to the clutch output shaft.When the central release mechanism is not actuated, the inner and outer plates separate, depending on the design, either through the action of a spring or – in the case of wet multi-plate brakes – through the oil flow between the plates.

[0029] In connection with the present invention, a multi-disc brake has the function of creating a releasable, friction-fit connection between a clutch input shaft and a clutch output shaft to support a rotational or braking torque.

[0030] A multi-plate brake typically consists of at least two inner and / or two outer plates. The inner plates are preferably arranged in a rotationally fixed manner on an inner plate carrier, and the outer plates are preferably arranged in a rotationally fixed manner on an outer plate carrier. The inner plate carrier is particularly connected to a clutch output shaft, and the outer plate carrier is particularly connected to a clutch input shaft, or vice versa.

[0031] The inner and outer plates form the plate pack of the multi-plate brake. Preferably, a plurality of inner and outer plates are arranged alternately relative to each other in the axial direction within the plate pack. The torque or braking force that can be transmitted by the multi-plate brake between the inner and outer plates can be adjusted by the number and design of the inner and outer plates.

[0032] The inner plates serve to transmit torque, particularly by frictional or force-fit, from the outer plates to the inner plate carrier. The inner plates can be designed as annular discs. They can be rotationally fixed to the inner plate carrier of the multi-plate brake. Furthermore, the inner plates can be displaced axially relative to the inner plate carrier, for example, via a corresponding toothed mechanism, to establish frictional engagement with the outer plates.

[0033] The outer plates serve to transmit torque, particularly by frictional or force-fit, from the inner plates to the outer plate carrier. The outer plates can be designed as annular discs. They can be rotationally fixed to the outer plate carrier of the multi-plate clutch. Furthermore, the outer plates can be displaced axially relative to the outer plate carrier, for example via a corresponding toothed mechanism, to establish frictional engagement with the inner plates. The outer plate carrier can, for example, be designed as an outer plate clutch basket.

[0034] The multi-plate brake may preferably include a spring. The spring's function is to move the inner and outer plates into a predefined position relative to each other. This predefined position typically corresponds to a "normally open" or "normally closed" operating state of the multi-plate brake, meaning that when the central release lever is not actuated, the inner and outer plates are either pressed against each other or released by the spring.

[0035] The multi-disc brake is actuated by the central release bearing. The central release bearing's function is to initiate a braking action of the multi-disc brake. This braking action can, in particular, involve engaging and / or disengaging the multi-disc brake. Since considerable force may be required to engage or disengage the multi-disc brake, the central release bearing may be designed to be actuated by means of hydraulic assistance.

[0036] Furthermore, the multi-disc brake can also have a switching piston. The switching piston's function is to convert the engagement and disengagement processes specified by the central release bearing into an axial displacement of the inner and / or outer plates for the purpose of establishing a frictional connection when engaging the clutch or releasing a frictional connection when disengaging the multi-disc brake.

[0037] According to an advantageous embodiment of the invention, the inner lamellae and / or the outer lamellae may be designed as steel lamellae. According to a further preferred embodiment of the invention, the inner lamellae and / or the outer lamellae may also have a splined connection.

[0038] Furthermore, according to an equally advantageous embodiment of the invention, it can be provided that the inner lamellae are received in an inner lamella carrier and / or the outer lamellae are received in an outer lamella carrier.

[0039] In a further preferred embodiment of the invention, it can also be provided that the shaft has an axially extending first fluid channel and a second fluid channel branching off from it and extending radially outwards through the shaft, at the outlet of which a cooling fluid can enter the brake device for cooling the friction device, wherein the first, cup-shaped housing part has a first connection opening for the inlet of the cooling fluid into the first fluid channel of the shaft, as well as a second connection opening for the outlet of the cooling fluid from the brake device.

[0040] This allows the brake system to be cooled effectively. Furthermore, it is possible to implement a wet friction brake system. The heat dissipated within the vehicle can then be used, for example, for air conditioning the passenger compartment.

[0041] The object of the invention is further achieved by an electrically operated axle drive train of a motor vehicle, comprising an electric machine with a stator and a rotatable rotor for driving at least one wheel of the motor vehicle, and a brake device that can be coupled to the wheel of the motor vehicle in such a way that actuation of the brake device causes the wheel of the vehicle to brake, wherein the brake device is designed according to one of claims 1-5.

[0042] According to a further preferred embodiment of the invention, the rotor of the electric machine and the shaft of the brake device may be arranged coaxially. Finally, the invention may also advantageously be implemented such that the rotor of the electric machine is permanently connected to the shaft of the brake device in a torque-transmitting manner.

[0043] The invention will now be explained in more detail with reference to figures, without limiting the general concept of the invention.

[0044] It shows: Fig. 1 a motor vehicle with an electric axle drive train and a braking device in a schematic block diagram, Fig. 2 an axle drive train with a brake device in a schematic block diagram, Fig. 3 a braking device in an axial section view, Fig. 4 A detailed view of the central release bearing in an axial section view.

[0045] The Fig. Figure 1 shows a braking device 1 in an electrically operated axle drive train 2 of a motor vehicle 3, wherein the braking device 1 can be coupled to a vehicle wheel 4 of the motor vehicle 3 in such a way that actuation of the braking device 1 causes the vehicle wheel 4 to brake.

[0046] For this purpose, the brake device 1 has, as shown in the Fig. 2 shows a hydraulic release system 5 with a central release bearing 6, which actuates a friction device 7 in such a way that it can be switched between a braking and non-braking operating state.

[0047] The central release bearing 6 has a central release bearing housing 8 with an annular central release bearing piston chamber 9, in which a central release bearing piston 11 is axially movably received by means of a hydraulic fluid 10 which can be supplied to the central release bearing piston chamber 9, wherein the central release bearing 6 has at least one central release bearing piston seal 12 which seals the central release bearing piston 11 against the central release bearing piston chamber 9, which can be clearly seen from the illustration of the Fig. 3 can be understood.

[0048] The central release bearing 6 and the friction device 7 are housed in a brake housing 13, the brake housing 13 being designed in two parts, comprising a cup-shaped first housing part 14 and a second lid-shaped second housing part 15, which at least partially covers the first cup-shaped housing part 15. As shown in the Fig. As shown in Figures 2-3, the lid-like second housing part 15 is formed by a motor housing 19 of an electric machine 20. The first pot-shaped housing part 14 is formed from a sheet metal part and thereby forms the central release housing 8 of the central release 6.

[0049] The central release piston chamber 9 of the central release bearing 6 is integrated into the one-piece, first cup-shaped housing part 14 of the brake device 1. The first housing part 14 thus forms the central release bearing housing 8. This central release piston chamber 9 is designed as a coaxial ring in which the central release bearing piston 11 is guided for axial displacement. Several through-holes are arranged on the outer diameter of the first cup-shaped housing part 14, through which the first housing part 14 is connected to the second, cover-like housing part 15 of the electric machine 20 by means of fastening screws 31. The fastening screws 31 absorb axial forces acting during operation and transmit them to the second housing part 15 of the electric machine 20. An O-ring groove with a seal 32 is arranged in the second housing part 15 of the electric machine 20 near the fastening screws 31.This serves to seal the wet room brake device 1 from the environment.

[0050] The multi-plate brake assembly is positioned and supported axially in the direction of the electric motor 20 by means of cylindrical domes 42, which are integrated into the second housing part 15 of the electric motor 20. The outer surface of the cylindrical domes 42, via the counter-geometry arranged in the outer plate carrier 38, absorbs the torque acting during operation and transmits it to the second housing part of the electric motor 20. The outer plate carrier 38 is connected to the second housing part 15 of the electric motor 20 and axially secured by fastening screws 33.

[0051] The brake housing 13 is penetrated by a shaft 16, which is connected to the friction device 7 of the brake assembly 1 in a torque-transmitting manner. The shaft 16 is supported relative to the cup-shaped first housing part 14 by means of a first rolling bearing 17, and a first bearing seat 18 for the first rolling bearing 17 is formed on the first cup-shaped housing part 14. The shaft 16 is further supported relative to the cup-shaped first housing part 14 by means of a second rolling bearing 21, and a second bearing seat 22 for the second rolling bearing 21 is correspondingly formed on the second cover-shaped housing part 15. The rotor 30 of the electric machine 20 and the shaft 16 of the brake assembly 1 are coaxial with each other, and the rotor 30 of the electric machine 20 is permanently connected to the shaft 16 of the brake assembly 1 in a torque-transmitting manner.

[0052] In the Fig. Figure 3 further shows that the friction device 7 is designed as a multi-disc brake. What the Fig. As can also be seen from Figure 3, the shaft 16 has a coaxially extending first fluid channel 23 and a second fluid channel 24 branching off from it and extending radially outwards through the shaft 16. A cooling fluid 26 can enter the brake device 1 at the outlet 25 of this second fluid channel 24 to cool the friction device 7. The first, cup-shaped housing part 14 has a first connection opening 27 for the inlet of the cooling fluid 26 into the first fluid channel 23 of the shaft 16, as well as a second connection opening 28 for the outlet of the cooling fluid 26 from the brake device 1. This enables the fluid transfer from the cooling fluid line 40 via the fluid channels 23 and 24 to the inner diameter of the inner plate carrier 37. Bores are arranged in the inner plate carrier 37 through which the cooling fluid 26 can pass into the plate pack of the multi-plate brake.The cooling fluid 26 reaches the inner wall of the first, pot-shaped housing part 14 via bores arranged in the outer fin carrier 38. From there, the cooling fluid 26 flows to the line 41, through which the cooling fluid 26 is discharged from the brake housing 13.

[0053] The shaft 16 of the brake device 1 is connected to the rotor shaft 34 of the electric machine 20 via a toothed connection 35 such that both speed and torque can be transmitted. The bearing for the shaft 16 of the brake device 1 is located in the motor housing 19 of the electric machine 20. A sliding belt 36 is also located in the same component.

[0054] In the Fig.Figure 4 shows the return mechanism of the central release bearing 6 in detail. The support plate 45 of the preload spring 44 is arranged on the axially stationary and non-rotating outer plate carrier 38. Domes for positioning the inner diameter of the preload spring 44, which is designed as a coil spring, are arranged in the support plate 45. A cylindrical receptacle 43 for the preload spring 44 is arranged in the central release bearing piston 11. The geometry with which the central release bearing piston 11 presses against the disc pack of the multi-disc brake is interrupted in the area of ​​the cylindrical receptacle 43. The distance between the support plate 45, the preload spring 44, and the upper edge of the central release bearing piston 11 defines the maximum release travel of the central release bearing piston 11. When actuated, in addition to the axial force required to generate the braking torque, the axial force to overcome the spring force of the preload springs 44 must also be applied.If no axial force is required to generate a braking torque, the preload spring 44 pushes the central release piston 11 away from the clutch pack. A stop is incorporated into the central release piston 11, which contacts the first housing part 14 at a defined travel, thus limiting the maximum distance of the central release piston 11 relative to the clutch pack.

[0055] The terms "radial," "axial," "tangential," and "circumferential direction" used in this application always refer to the axis of rotation of the brake device's shaft. The terms "left," "right," "above," "below," "above," and "below" serve only to clarify which areas of the figures are currently being described in the text. Later embodiments of the invention may be arranged differently. Furthermore, the invention is not limited to the embodiments shown in the figures. The foregoing description is therefore not to be considered limiting, but rather explanatory. The following claims are to be understood as meaning that a named feature is present in at least one embodiment of the invention. This does not preclude the presence of other features.If the patent claims and the preceding description define 'first' and 'second' feature, this designation serves to distinguish between two similar features without establishing a hierarchy. Reference symbol list 1 Brake device 2 axle drive train 3 Motor vehicle 4 vehicle wheels 5 Release system 6 Central release bearings 7 Friction device 8 Central release bearing housing 9 Central release piston chamber 10 Hydraulic fluid 11 Central release piston 12 Central release piston seal 13 brake housings 14 Housing part 15 Housing part 16 wave 17 rolling bearings 18 bearing seat 19 Engine housings 20 electric machine 21 rolling bearings 22 bearing seat 23 Fluid channel 24 Fluid channel 25 Exit 26 Cooling fluid 27 Connection opening 28 Connection opening 29 Stator 30 Rotor 31 Mounting screw 32 Seal 33 Mounting screw 34 Rotor shaft 35 toothing 36 sliding belt 37 internal slat carriers 38 outer slat carriers 39 Pressure line 40 Cooling fluid line 41 Cooling fluid line 42 cylindrical dome 43rd entry 44 Preload spring 45 Support plate

Claims

[1] Braking device (1) for an electrically operable axle drive train (2) of a motor vehicle (3), wherein the braking device (1) can be coupled to a vehicle wheel (4) of the motor vehicle (3) in such a way that actuation of the braking device (1) causes braking of the vehicle wheel (4), wherein the braking device (1) comprises a hydraulic release system (5) with a central releaser (6) which actuates a friction device (7) such that the latter can be transferred into a braking and non-braking operating state, and the central releaser (6) further comprises a central releaser housing (8) with an annular central releaser piston chamber (9) in which a central releaser piston (11) is accommodated so as to be axially movable by means of a hydraulic fluid (10) which can be supplied to the central releaser piston chamber (9), wherein the central releaser (6) has at least one central releaser piston seal (12) which seals the central releaser piston (11) against the central releaser piston chamber (9), and the central releaser (6) and the friction device (7) are accommodated in a brake housing (13), wherein the brake housing (13) is formed in two parts, comprising a pot-like first housing part (14) and a second cover-like second housing part (15) which covers the first pot-like housing part (15) at least in sections, wherein the first pot-like housing part (14) forms the central release housing (8) of the central release (6). characterized by , that the brake housing (13) is penetrated by a shaft (16) which is connected to the friction device (7) of the braking 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 first pot-shaped housing part (14), and that the shaft (16) is mounted relative to the pot-like 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 second cover-like housing part (15). [2] Braking device (1) according to claim 1, characterized by that the cover-like, second housing part (15) is formed by a motor housing (19) of an electrical machine (20). [3] Braking device (1) according to one of the preceding claims, characterized by that the first, pot-shaped housing part (14) is formed from a sheet metal. [4] Braking device (1) according to one of the preceding claims, characterized by that the friction device (7) is designed as a multi-disk brake. [5] Braking device (1) according to one of the preceding claims, characterized byin that the shaft (16) has an axially extending first fluid channel (23) and a second fluid channel (24) branching off from it and extending radially outwards through the shaft (16), at the outlet (25) of which a cooling fluid (26) for cooling the friction device (7) can enter the braking device (1), wherein the first, pot-shaped housing part (14) has a first connection opening (27) for the inlet of the cooling fluid (26) into the first fluid channel (23) of the shaft (16), and also provides a second connection opening (28) for the outlet of the cooling fluid (26) from the braking device (1). [6] Electrically operable axle drive train (2) of a motor vehicle (3), comprising an electric machine (20) with a stator (29) and a rotor (30) rotatable thereto for driving at least one vehicle wheel (4) of the motor vehicle (3), and a braking device (1) which can be coupled to the vehicle wheel (4) of the motor vehicle (3) in such a way that actuation of the braking device (1) causes braking of the vehicle wheel (4), characterized by that the braking device (1) is designed according to one of the preceding claims. [7] Axle drive train (2) according to claim 6, characterized by that the rotor (30) of the electric machine (20) and the shaft (16) of the braking device (1) run coaxially to one another. [8] Axle drive train (2) according to claim 6 or 7, characterized by that the rotor (30) of the electric machine (20) is permanently connected to the shaft (16) of the braking device (1) in a torque-transmitting manner.

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