Friction disc brake system for a motor vehicle

Abstract

The invention relates to a friction disc brake device (28) for a motor vehicle, comprising a lining disc (34) arranged coaxially to at least a part (20) of an output shaft (16) and axially between a first brake disc (30) and a second brake disc (32) of the friction disc brake device (28), wherein an interior space (44) of the friction disc brake device (28) is surrounded by a housing (36) through which the output shaft (16) penetrates. The first brake disc (30) and the second brake disc (32) are rotationally fixed to the housing (36) at their respective outer circumferences. The lining disc (34) is rotationally fixed to the output shaft (16) via a support element (51) and thereby indirectly.The support element (51) has several air passage openings (66) on its circumference, through which a first sub-space (T1) of the interior (44), in whose first sub-space (T1) the first brake disc (30) is arranged, and a second sub-space (T2) of the interior (44), in whose second sub-space (T2) the second brake disc (32) is arranged, are fluidically connected to each other.

Description

[0001] The invention relates to a friction disc brake device for a motor vehicle.

[0002] The state of the art includes DE 198 23 025 A1.

[0003] The object of the present invention is to create a particularly advantageous friction disc brake device for a motor vehicle.

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

[0005] The invention relates to a friction disc brake device, also referred to simply as a brake, braking system, friction brake, friction brake assembly, or disc brake device, for a motor vehicle, also referred to simply as a vehicle. In particular, the friction disc brake device is integrated into a housing of the motor vehicle, especially an axle component of the motor vehicle. The axle component is, for example, an axle drive device, in particular an electric axle drive device, or an axle transmission, also referred to as a differential or differential gear, or a chassis component such as an axle carrier. When the braking system is mentioned above and below, unless otherwise specified, this refers to the friction disc brake device according to the invention. In particular, the friction disc brake device is or constitutes a service brake of the motor vehicle.For example, the friction disc brake assembly is integrated into the axle component by being at least partially arranged within the housing of the axle component and thus integrated into the housing. The brake assembly (friction disc brake assembly) has a housing assembly, which can, for example, be part of the housing. The friction disc brake assembly is arranged coaxially to at least part of an output shaft of the motor vehicle, in particular the axle component, and has a friction disc arranged axially between a first brake disc of the friction disc brake assembly and a second brake disc of the friction disc brake assembly, which is also referred to as a counter-rotating disc. In particular, the brake discs and the friction disc are each at least partially arranged within the housing assembly.In this process, an interior space of the friction disc brake assembly, also referred to as the receiving space, is surrounded by the housing assembly and thereby, in particular directly, bounded by the housing assembly, especially by an inner circumferential surface of the housing assembly. The housing assembly, in particular the interior space, is penetrated by the output shaft, which is also referred to as the shaft, side shaft, or drive shaft. At least the portion of the output shaft is rotatable about an axis of rotation relative to the housing assembly of the friction disc brake assembly, the axial direction of which coincides with the axis of rotation. When the axial direction is mentioned before and below, this refers, unless otherwise specified, to the axial direction of the friction disc brake assembly. "Axial" means the axial direction of the friction disc brake assembly, the radial direction of which is perpendicular to the axial direction and thus perpendicular to the axis of rotation.When the radial direction is mentioned before and below, unless otherwise specified, this refers to the radial direction of the friction disc brake assembly. "Radial" means the radial direction of the friction disc brake assembly, whose circumferential direction runs around the axis of rotation and extends in an imaginary plane perpendicular to the axis of rotation and thus perpendicular to the axial direction.

[0006] The first brake disc and the second brake disc are connected to the housing assembly at their respective outer circumferences in a rotationally fixed manner, so that the pad disc (also referred to as the pad carrier disc) and at least part of the output shaft are rotatable about the axis of rotation relative to the housing assembly and relative to the brake discs. In particular, part of the output shaft is or forms a shaft section of the output shaft and / or a joint section of the output shaft. The pad disc is connected to the output shaft, i.e., at least to part of the output shaft, via a carrier element and thus indirectly, and is rotatable with at least part of the output shaft about the axis of rotation relative to the brake discs and relative to the housing assembly. The carrier element has several air passage openings on its outer circumference, through which a first sub-compartment of the interior and a second sub-compartment of the interior are fluidically connected to each other.The first brake disc is arranged in the first compartment, and the second brake disc is arranged in the second compartment. In particular, the compartments are separated from each other by the support element, especially by a wall of the support element, so that, for example, the interior space is divided into the compartments by the support element, especially by the wall of the support element. The air passage openings, designed as through-openings, are arranged in the wall, which is penetrated, in particular completely, by the air passage openings.

[0007] At least when the friction disc brake assembly, also simply referred to as a brake, is in its open (i.e., unactuated) state, air circulation can develop due to the air passage openings. The background of the invention is, in particular, that integrated friction brakes, such as the friction disc brake assembly according to the invention, become hotter than wet-running friction brakes, especially when they are designed to run dry. Furthermore, because the friction disc brake assembly is integrated into the housing, the airflow from driving does not readily reach the friction disc brake assembly. The air passage openings enable the described internal air circulation, which has a cooling and balancing effect, particularly in that the two brake discs can reach different temperatures.Air circulation allows for heat equalization between brake discs, thus preventing excessively high temperatures in the friction disc brake system.

[0008] In an advantageous embodiment of the invention, it is provided that the brake discs each have at least one air guide channel, which extends from a respective inner circumference to a respective outer circumference of the respective brake disc.

[0009] In an advantageous embodiment of the invention, it is provided that the air guide channels extend radially from a respective inner circumference to a respective outer circumference of the respective brake disc.

[0010] In an advantageous embodiment of the invention, it is provided that the brake discs are connected to the housing assembly in a rotationally fixed manner at their respective outer circumference via a respective splined connection.

[0011] In particular, because the air guide channels extend radially, an internal air circulation can form even when the friction disc brake device is in operation, thus preventing excessively high temperatures in the friction disc brake device.

[0012] The respective splined connection has, for example, sufficient play at least locally, so that air ingress into the respective air duct and air outlet from the respective air duct are advantageously possible.

[0013] The aforementioned wall is, or forms, for example, a so-called hub shell, which, due to the air passage openings penetrating it, is a perforated hub shell. These air passage openings function, for example, as air guides, which create or promote and maintain a torus-shaped airflow, thereby reducing, minimizing, or even preventing excessive temperature differences within the friction disc brake assembly.

[0014] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0015] The drawing shows in: Fig. 1. Partial schematic longitudinal sectional view of a friction disc brake assembly; and Fig. 2. Partially shown is another schematic longitudinal section view of the friction disc brake device.

[0016] In the figures, identical or functionally equivalent elements are provided with the same reference symbols.

[0017] Fig. Figure 1 shows a partial schematic longitudinal section of an axle drive unit 10 of a motor vehicle, also referred to simply as a vehicle. The axle drive unit 10 has a housing 12, which defines an interior space 14. For example, a drive motor of the axle drive unit 10 is arranged in the interior space 14, the drive motor being an electric motor. The motor vehicle has, for example, a vehicle axle, also referred to simply as an axle, which has at least or exactly two vehicle wheels. The vehicle wheels, also referred to simply as wheels, are arranged on opposite sides of the motor vehicle in the transverse direction. The axle drive unit 10 has a shaft 16, which is also referred to as an output shaft, drive shaft, or side shaft and is designed in this case as a cardan shaft.The drive motor can drive at least one of the vehicle wheels, particularly in the vicinity of the other vehicle wheel, via shaft 16. The vehicle wheels are the ground contact elements of the motor vehicle. A bellows is designated 18.

[0018] The shaft 16, designed here as a cardan shaft, comprises a first shaft section 20, a second shaft section 22, and a joint 24, which is designed, for example, as a tripod joint, i.e., a constant velocity joint. The shaft sections 20 and 22 are articulated to each other via the joint 24. At least the shaft section 20 is rotatable about an axis of rotation 26 relative to the housing 12 of the axle drive unit 10, the axial direction of which coincides with the axis of rotation 26.

[0019] The axle drive unit 10 has a brake unit 28 whose axial direction coincides with the axis of rotation 26 and thus with the axial direction of the axle drive unit 10. The brake unit 28, whose radial direction is perpendicular to the axis of rotation 26 and thus perpendicular to the axial direction of the brake unit 28, is also referred to as a friction disc brake unit and is designed as a friction disc brake unit. Where the radial direction is mentioned before and below, this refers, unless otherwise specified, to the radial direction of the brake unit 28. Where the axial direction is mentioned before and below, this refers, unless otherwise specified, to the axial direction of the brake unit 28."Axial" refers to the axial direction, and "radial" refers to the radial direction of the braking device 28, whose circumferential direction runs around the axis of rotation 26 and extends in an imaginary plane that is perpendicular to the axial direction and perpendicular to the axis of rotation 26.

[0020] The brake assembly 28 has a pad disc 34, also referred to as a carrier disc or pad carrier disc, arranged coaxially to the shaft 16 and axially between a first brake disc 30 and a second brake disc 32. The brake discs 30 and 32 and the pad disc 34 are components of the brake assembly 28. Each brake disc 30, 32 has a friction surface R1, R2, respectively. The pad disc 34 has a friction surface R3 corresponding to friction surface R1 and a friction surface R4 corresponding to friction surface R2. The brake assembly 28 has a housing assembly 36. The housing 12 has a first housing part 38 and a second housing part 40, wherein the housing parts 38 and 40 are formed separately from one another and are connected to each other by means of at least one screw connection 42. The housing parts 38 and 40 are, or form, the housing assembly 36.The housing assembly 36 defines a receiving space 44 of the brake assembly 28, also referred to as the interior, in which the brake discs 30 and 32 and the friction disc 34 are arranged. It can be seen that the receiving space 44 of the friction disc brake assembly, also referred to as the interior, is surrounded by the housing assembly 36. The shaft 16 penetrates the housing assembly 36. The brake discs 30 and 32 are non-rotatably connected to the housing assembly 36 and thus to the housing 12. For this purpose, each brake disc 30, 32 is non-rotatably connected to the housing assembly 36 at its respective outer circumference.

[0021] The lining disc 34 is connected to the shaft part 20 and thus to the shaft 16 in a rotationally fixed manner via a support element 51 of the brake device 28, so that the lining disc 34, the support element 51 and the shaft part 20 can be rotated together about the axis of rotation 26 relative to the housing device 36, relative to the housing 12 and relative to the brake discs 30 and 32.

[0022] By actuating the brake device 28, particularly hydraulically, the friction surfaces R1 and R3 and the friction surfaces R2 and R4 can be brought into direct, mutual, friction-fit contact, whereby the friction disc 34 and thus the shaft section 20 can be braked, i.e., slowed down, for rotation about the axis of rotation 26 and relative to the housing device 36. The shaft 16 can be connected to or is connected to at least one vehicle wheel in a torque-transmitting manner, so that at least one vehicle wheel can be driven by the drive motor via the shaft 16.At least one or exactly one vehicle wheel is rotatable about a wheel axis relative to the housing assembly 36 and the housing 12. When at least one or exactly one vehicle wheel rotates about the wheel axis relative to the housing assembly 36, the shaft section 20, the support element 51, and the friction disc 34 are rotatable with the vehicle wheel about the axis of rotation 26 relative to the housing assembly 36 and relative to the brake discs 30 and 32. Consequently, by braking, i.e., by braking the friction disc 34 and thus the shaft section 20, the shaft 16 can be slowed down, i.e., braked. This slows down the rotation of at least one or exactly one vehicle wheel about the wheel axis relative to the housing assembly 36, i.e., brakes it, thus at least reducing its speed. As a result, the entire vehicle can be braked, i.e., slowed down.

[0023] The brake disc 32 is rotationally fixed and axially fixed to the housing assembly 36. The brake pad 34 is rotationally fixed to the shaft section 20 and is therefore rotatable about the axis of rotation 26 relative to the brake discs 30 and 32 and relative to the housing assembly 36, whereby the brake pad 34 is axially movable relative to the housing assembly 36 and also relative to the brake disc 32, i.e., it is displaceable. The brake disc 30 is rotationally fixed to the housing assembly 36, but the brake disc 30 is axially displaceable relative to the housing assembly 36, relative to the brake disc 32, and also relative to the brake pad 34. By actuating the brake device 28, in particular hydraulically, the brake disc 30 and thus the friction surface R1 can be moved axially towards the friction surface R3 and thus the pad disc 34, whereby the pad disc 34 and thus the friction surface R4 can be moved axially towards the friction surface R2 and thus the brake disc 32.This allows the friction surfaces R1 and R3 and the friction surfaces R2 and R4 to be brought into direct, mutual, friction-fit contact, thereby braking the shaft 16 and, via this, the vehicle's degree of travel.

[0024] The respective friction surfaces R3, R4 are formed, for example, by a respective friction lining provided on the friction disc 34. For example, the brake disc 32 is designed as a friction plate.

[0025] The respective brake disc 30, 32 is connected to the housing part 38 and thus to the housing assembly 36 in a rotationally fixed manner via a drive toothing 48. For example, the housing part 38 is a side cover, also referred to as an intermediate cover. For example, the housing part 40 is an end cover. For example, the friction disc 34 is connected to the support element 51 in a rotationally fixed manner via a drive toothing 46. A ring cup spring 50 is also provided, which is elastically deformed by actuating the brake device 28 and thereby provides a spring force, at least when the brake device 28 is actuated, by means of which the friction disc 34 can be reset, allowing the friction surface R4 to be axially moved away from the friction surface R2. A bearing designed as a rolling bearing is designated 52, wherein the shaft 16 is rotatably mounted on the housing assembly 36 by means of the bearing 52.

[0026] The brake assembly 28 also includes a piston 54, also referred to as an actuating piston, which is designed, for example, as a ring piston. An actuating chamber 56 is also provided, which is partially and directly bounded by the piston 54 and partially and directly by the housing part 40 (end cap). Hydraulic fluid can be introduced into the actuating chamber 56, allowing the piston 54 to be directly actuated by the hydraulic fluid. This enables the piston 54 to be moved axially towards the brake disc 30 via a transmission element 58, thereby moving the friction surface R1 towards the friction surface R3, and thus the friction surface R4 towards the brake disc 32 and the friction surface R2. This allows the vehicle wheel to be braked.A radial shaft seal is designated 60, wherein the housing part 40 is sealed against the side shaft or against a sleeve 62 of the side shaft by means of the radial shaft seal. For example, the sleeve 62 is rotationally fixed to the shaft part 20.

[0027] The support element 51 has a wall 64 designed as a solid body, which forms a so-called hub pot. The hub pot divides the receiving space 44, also referred to as the interior, into a first sub-space T1 and a second sub-space T2, wherein the brake disc 30 is arranged in sub-space T1 and the brake disc 34 in sub-space T2. In this case, air passage openings 66 are formed in the wall 64, which, as shown in Fig. 1. As illustrated by arrows, air can flow through them. Thus, they illustrate in Fig. 1 The arrows represent an airflow, also referred to as air circulation or designed as air circulation, in which air flows through the air openings 66. It can be seen that the sub-spaces T1 and T2 of the interior (receiving space 44) are fluidically connected to each other via the air openings 66.

[0028] It is evident that the intermediate cover, designated as the side cover, at least partially closes off the receiving chamber 14, particularly towards the surroundings 68 of the axle drive unit 10. The brake unit 28 is located in the intermediate cover. The housing part 40 is the aforementioned, particularly annular, end cover, which at least partially closes off the receiving chamber 44, particularly towards the surroundings 68. It is evident that the piston 54 is located in the end cover and is thus integrated into it.

[0029] Each brake disc 30, 32 has at least one air guide channel L1, L2, which extends from its respective inner circumference to its respective outer circumference. Multiple air guide channels L1, L2 are conceivable, extending, for example, radially from the respective inner circumference to the respective outer circumference of the respective brake disc 30, 32. The drive toothing 48 is, for example, a first splined connection into which a corresponding second splined connection of the respective brake disc 30, 32 engages, thereby connecting the respective brake disc 30, 32 to the housing assembly 36 in a rotationally fixed manner.

[0030] The friction surface R1 is axially movable, while the friction surface R2 is axially fixed. Thus, the brake disc 30 is axially movable, as is the pad disc 34, while the brake disc 32 is axially fixed. If no countermeasures are taken, the brake discs 30 and 32 will be cooled to varying degrees and can therefore reach different temperatures during braking. These temperatures can be transferred to the pad carrier disc (pad disc 34). If the brake discs 30 and 32 have different temperatures, and these temperatures differ excessively, the pad disc 34 can warp, which can lead to the pad disc 34 braking more strongly on its hotter side at an inner radius and on its cooler side at an outer radius. This can result in an uneven pressure distribution, which can lead to excessive wear and localized excessive stress.This can now be avoided. The air passage openings 66 enable the aforementioned air circulation. The hub thus functions as an air conveying and air guiding device, which, for example, initiates and maintains an at least substantially torus-shaped airflow, thereby preventing excessive temperature differences between the brake discs 30 and 32. This results in at least substantially uniform temperature exposure, so that the pad disc 34 runs almost without distortion and parallel to the surface, even under high loads. This leads to at least substantially uniform surface pressure, which prevents excessive wear.

[0031] The axle drive unit 10 is also referred to as a drive module, particularly an electric one, and is arranged, for example, with its output shafts coaxially to the vehicle wheels. The drive module drives the vehicle wheels by means of its output shafts, also referred to as drive shafts, one of which is the shaft 16. The drive module has a side cover on its end face. The shaft 16 is supported in the side cover by means of the bearing 52, which is designed, for example, as a radial groove ball bearing. The shaft 16, also referred to as the drive shaft, therefore runs centered on the side cover. The shaft 16 has the joint 24 as a universal joint. Radially on the outside of the joint 24, the hub cup, which has air passage openings 66 and is therefore perforated, is arranged with the drive teeth 46, wherein, for example, the respective air passage opening 66 can be produced as a bore and thus by machining.In particular, the hub is permanently and rotationally fixed to the joint 24 or to its joint part formed by the shaft section 20. The friction disc 34 is arranged axially displaceably but torque-transmitting and thus rotationally fixed on the drive teeth 46. The friction disc 34 interacts with the friction surface R2 for braking. The brake disc 30 is arranged on the other side of the friction disc 34. The brake disc 30 is arranged rotationally fixed and thus torque-transmitting but axially displaceable and centered in the side cover by means of the drive teeth 48. The brake assembly 28 is covered and thus closed by the end cover. The piston 54, designed as a hydraulically actuated annular piston, is integrated into the end cover.During braking, the hydraulically actuated ring piston presses axially against the brake disc 30 and presses it against the pad disc 34, which in turn presses the pad disc against the brake disc 32, which acts as a friction plate.

[0032] This is an actuation of the brake disc 30, which generates a braking torque on the friction surfaces R1-4. The resulting brake heat from the deceleration is generated, at least substantially, in or on the friction surfaces R1-4. Since the brake disc 32 is connected to the side cover, at least substantially, over its entire surface, brake heat from the brake disc 32 can be efficiently transferred to the side cover and thus to the housing assembly 36 via thermal conduction.

[0033] The air guide channels L1 and L2 are preferably arranged radially and / or designed as bores and thus manufactured by machining. The air guide channels L1 and L2 are therefore air guide channels or air guide bores. The air passage openings 66 of the hub top, designed, for example, as air conveying bores, function as an air conveying device and as an air passage between two axially opposite sides of the friction disc 34 and thus between the partial spaces T1 and T2. The friction disc 34, with its closed hub, serves as an air guide. This ensures that air must flow through the air passage openings 66 in the area within the inner radius of the friction disc 34, and thus the air is conveyed via the air passage openings 66 when the friction disc 34 rotates. The air is conveyed radially outwards by a centrifugal blower function that is established.From here, the air flows along the inner radius of the brake disc 30 into the air guide channels L1 integrated into it. In the region of its outer radius, the air leaves the brake disc 30 and flows axially towards the brake disc 34. The air then flows radially inwards through the air guide channels L2 of the brake disc 32 and back towards the air conveying device. Overall, an internal, at least substantially torus-shaped airflow is established in the receiving chamber 44. The air in the receiving chamber 44, and thus inside the brake assembly 28, is circulated. Depending on the temperature difference, energy transfer takes place in the air guide channels L1 and L2 of the brake discs 30 and 32 between the respective brake discs 30 and 32 and the air flowing through them. This leads to intensive heat exchange between the individual components within the brake assembly 28, particularly between the brake disc 30 and the brake disc 32.Temperature differences between these two components are equalized. As a result, the brake pad 34 is exposed to at least approximately the same temperature on both sides, so that the brake pad 34 does not warp due to temperature even during heavy braking.

[0034] Looks especially good Fig. Figure 2 shows the shaft section 20, to which the support element 51, which is formed separately from the shaft section 20, is connected in a rotationally fixed manner. Particularly well seen from Fig. 2 The air passage openings 66 of the hub pot, and thus of the support element 51, are also recognizable. Reference symbol list 10 axle drive unit 12 cases 14 Interior 16 wave 18 bellows 20 shaft part 22 shaft part 24 joint 26 axis of rotation 28 Brake system 30 brake disc 32 brake disc 34 coating disc 36 Housing design 38 Housing part 40 Housing part 42 screw connection 44 Recording Room 46 Drive gear 48 Drive teeth 50 ring pot springs 51 Support element 52 Storage 54 pistons 56 Activity area 58 Transmission element 60 Radial shaft seal 62 Sleeve 64 wall 66 Air passage opening L1 Air duct L2 air duct T1 subspace T2 sub-area R1 -4 friction surface QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 198 23 025 A1

[0002]

Claims

Friction disc brake device (28) for a motor vehicle, comprising a lining disc (34) arranged coaxially to at least a part (20) of an output shaft (16) and axially between a first brake disc (30) and a second brake disc (32) of the friction disc brake device (28), wherein: - an interior space (44) of the friction disc brake device (28) is surrounded by a housing device (36) which is penetrated by the output shaft (16); - the first brake disc (30) and the second brake disc (32) are connected to the housing device (36) at their respective outer circumferences in a rotationally fixed manner; - the lining disc (34) is connected to the output shaft (16) in a rotationally fixed manner via a support element (51) and thereby indirectly;and- the support element (51) has several air passage openings (66) on its circumference, through which a first sub-space (T1) of the interior (44), in the first sub-space (T1) of which the first brake disc (30) is arranged, and a second sub-space (T2) of the interior (44), in the second sub-space (T2) of which the second brake disc (32) is arranged, are fluidically connected to each other.; Friction disc brake device (28) according to claim 1, characterized in that the brake discs (30, 32) each have at least one air guide channel (L1, L2) which extends from a respective inner circumference to a respective outer circumference of the respective brake disc (30, 32). Friction disc brake device (28) according to claim 2, characterized in that the air guide channels (L1, L2) extend radially from a respective inner circumference to a respective outer circumference of the respective brake disc (30, 32). Friction disc brake device (28) according to one of the preceding claims, characterized in that the brake discs (30, 32) are connected to the housing device (36) in a rotationally fixed manner at their respective outer circumference via a respective splined connection.

Images