Brake system

Abstract

The invention relates to a brake system (1) of a motor vehicle (3) which can be electrically driven by an electric machine (2), said brake system (1) comprising a disc brake (4) having a brake disc (5) and a brake caliper (7) which can be frictionally connected to the brake disc (5) on an end face (6) thereof, the motor vehicle (3) has a brake disc (5) and the electric machine (2) has a rotor (8) which is coupled in a torque-transmitting manner to at least one wheel (9) of the motor vehicle (3), the disc brake (4) is accommodated in a brake housing (9) and the brake disc (5) of the disc brake (4) is connected in a torque-transmitting manner to the rotor (8) of the electric machine (2), the brake disc (5) has a hydraulic brake disc cooling system (10), in which a shell surface (11) of the brake disc (5) can be applied with a brake disc cooling fluid (12), which can be introduced through a fluid inlet (13) in the brake housing (9), and can be discharged from the brake housing through a fluid outlet (14) in the brake housing (9).

Description

Field of the Invention

[0001] The invention relates to a braking system for a motor vehicle that can be electrically driven by means of an electric motor, wherein the braking system comprises a disc brake having a brake disc and a brake caliper, the brake caliper being frictionally connectable to the brake disc at the end face of the brake disc, and the electric motor having a rotor that is torsionally coupled to at least one wheel of the motor vehicle. Background of the Invention

[0002] Electric motors are increasingly being used as drives in motor vehicles to provide an alternative to internal combustion engines that require fossil fuels. Considerable efforts have been made to improve the suitability of electric drives for everyday use and to also be able to offer users the driving comfort to which they are accustomed. A detailed description of electric drives can be found, for example, in an article by Erik Schneider, Frank Fickl, Bernd Cebulski, and Jens Liebold in the magazine ATZ, Volume 113, Pages 360 to 365, May 2011, entitled: Hochintegrativ und Flexibel Elektrische Antriebseinheit für E-Fahrzeuge [Highly integrative and flexible electric drive unit for electric vehicles]. The article describes a drive unit for a vehicle axle that includes an electric motor that is arranged coaxially with respect to a bevel gear differential.

[0003] Motor vehicles of this type with a hybrid or electric powertrain can not only accelerate but also brake by means of the electric motor. For example, during the braking process, the electric motor operates as a generator and the recovered energy is used to charge the battery. However, for safety reasons, an additional mechanical braking device is still required. This results in a more difficult installation space situation for drives close to the wheels, such as hub motors or electric axles.

[0004] In particular, vehicles that include an electric hub drive, i.e., a so-called electric wheel drive, typically use a brake with a plate to brake the vehicle. However, disc brakes with floating calipers, disc brakes with fixed calipers, drum brakes, and multi-disc brakes are also known.

[0005] For example, DE 10 2019 120 409 A1 discloses a braking device for a wheel hub drive assembly, wherein the braking mating part fixed relative to the circumferential direction has a cooling channel. The axially movable braking mating part is actuated via a brake cylinder. The braking mating part movable in the circumferential direction is designed as a plate-shaped carrier. SUMMARY OF THE INVENTION

[0006] The object of the present invention is to provide a braking system for a motor vehicle that can be electrically driven by means of an electric motor, and the braking system is improved in terms of its cooling.

[0007] This object is achieved by a braking system of a motor vehicle that can be electrically driven by means of an electric motor, the braking system comprising a disc brake having a brake disc and a brake caliper, the brake caliper being frictionally connectable to the brake disc at the end face of the brake disc, and the electric motor having a rotor that is torque-transmittingly coupled to at least one wheel of the motor vehicle, wherein the disc brake is accommodated in a brake housing, and the brake disc of the disc brake is torque-transmittingly connected to the rotor of the electric motor, and the brake disc has a hydraulic brake disc cooling system in which a brake disc cooling fluid can be applied to the shell surface of the brake disc and can be introduced through a fluid inlet of the brake housing and can be discharged from the brake housing via a fluid outlet of the brake housing.

[0008] The advantage of this is that a type of complementary brake is coupled to the electric motor, which can exert a braking effect on the wheel. In order to be able to exert a high braking torque to decelerate the motor vehicle without a reduction in braking performance due to heat, the braking system also has a fluid-based brake disc cooling system.

[0009] The preferred arrangement directly near the electric drive machine also means that the heat energy recovered from the braking process by the fluid-based brake disc cooling system and the heat energy generated near the potential heat dissipator do not need to be transported over a long distance through the vehicle, and transporting over a long distance through the vehicle is associated with losses.

[0010] First, now the individual elements of the subject matter claimed in the present invention are explained in the order in which they are mentioned in the claim group, and particularly preferred embodiments of the subject matter of the present invention are described below.

[0011] The braking system according to the present invention has a function of braking, for example, by frictionally connecting a brake shaft.

[0012] For this purpose, the braking system according to the invention is arranged in a brake housing. The brake housing encloses the braking system. The brake housing can also accommodate one or more brake actuators. The brake housing can also be part of a cooling system and is designed such that cooling fluid is fed to the braking system via the brake housing and / or heat can be dissipated to the outside via the housing surface. The brake housing also protects the braking system from external mechanical and / or chemical influences. In particular, the brake housing can be formed from a metallic material. Advantageously, the brake housing can be formed from a metallic casting material such as grey cast iron or cast steel. In principle, it is also conceivable for the brake housing to be made completely or partially from plastic. The brake housing can also be designed as one piece or several parts. The brake housing can also be designed completely or partially as part of the motor housing of an electric motor or as part of the transmission housing of a transmission coupled to the electric motor. Preferably, the brake housing and the motor housing or the transmission housing form a structural unit. For example, the brake housing can be bolted to the motor housing or the transmission housing. The brake housing is arranged in a rotationally fixed manner relative to the disc brake. The brake housing is preferably designed such that wear particles generated during braking cannot escape from the brake housing. This prevents unnecessary contamination of the environment by brake wear particles. By encapsulating the braking system in this way, the braking noise relative to the environment can also be reduced. Another advantageous aspect of this encapsulation is that the braking performance of the braking system is independent of the weather conditions outside the motor vehicle.

[0013] The braking system according to the invention includes a disc brake. The brake disc is the rotating part of the disc brake, and the brake caliper acts on the end face of the brake disc in a releasable manner in order to decelerate the rotational movement of the brake disc by means of frictional connection during the operation of the disc brake. The brake disc preferably has a brake disc body.

[0014] The brake disc can preferably be formed from cast metal, in particular grey cast iron, ductile cast iron or cast steel, and is then preferably machined by turning and / or milling. Carbon fiber-reinforced silicon carbide and / or carbon fiber-reinforced ceramic materials can also be used in order to achieve a particularly low brake disc weight. It is also conceivable that, in particular for the cost-effective provision of the brake disc, the brake disc is stamped out of sheet metal.

[0015] The brake disc preferably has a hollow cylindrical three-dimensional shape, the axial extension of which is significantly smaller than its diameter. The brake disc can be made from one or more parts. In the case of a multi-part brake disc, the individual brake disc elements can preferably be arranged in layers in the axial direction, thus forming a kind of sandwich construction.

[0016] The brake disc body is part of the brake disc, on which the brake caliper acts frictionally to reduce the rotational speed of the brake disc. The brake disc body can have a plurality of brake disc cooling channels, which can be used in particular to dissipate heat and / or brake wear particles from the brake disc body.

[0017] The braking system can also have a shaft connection. The shaft connection of the brake disc connects the brake disc body to the rotating shaft to be braked, also called the brake shaft. The shaft connection can be designed as a separate component, which is arranged in the torque flow between the brake disc body and the shaft to be braked, or can be designed as a connection between the brake disc body and the shaft to be braked. The shaft to be braked and the shaft connection can be formed as one piece, in particular integrally. In principle, it is also conceivable that the shaft connection and the brake disc body are designed as one piece. It is also preferable that the shaft to be braked, the shaft connection and the brake disc body are formed as one piece, in particular integrally. The shaft connection can also be established, for example, by means of an interlock, friction and / or integral connection between the shaft to be braked and the brake disc body. For example, the shaft connection can be made by means of a press fit, splines or welding.

[0018] The braking system according to the invention has a hydraulic brake disc cooling system. The hydraulic brake disc cooling system uses a brake disc cooling fluid to cool the brake disc. In this case, the brake disc cooling fluid can act on the brake disc at least segmentally and / or be guided through the brake disc. Preferably, the hydraulic brake disc cooling system is designed such that the brake disc cooling fluid cannot reach the friction surface between the brake caliper and the brake disc body.

[0019] For this purpose, the hydraulic brake disc cooling system can have at least one, but preferably a plurality of, brake disc cooling channels, through which the brake disc cooling fluid is guided.

[0020] It is also preferable that the hydraulic brake disc cooling system is connected to a brake disc cooling circuit, within which the frictional heat absorbed by the brake disc cooling fluid is dissipated from the disc brake and fed to a radiator, such as a heat exchanger.

[0021] In order to produce a frictional connection between the brake caliper and the brake disc, the brake caliper, in particular its brake caliper friction linings, is preferably axially pressed against the brake disc by means of a brake actuator.

[0022] The braking system may also have a brake actuator. In particular, the brake actuator has the function of enabling the brake, i.e., setting the brake into a friction operating state and an operating state of releasing from the frictional connection. In particular, the brake actuator can be actuated pneumatically, hydraulically, by an electric motor, mechanically, electromagnetically, or by any combination of these means. The brake actuator preferably has at least one linearly displaceable piston, which preferably can be displaced in the axial direction. Preferably, the brake actuator includes two linearly displaceable pistons, and more preferably, the pistons can be displaced towards each other.

[0023] The braking system according to the invention is provided for a motor vehicle that can be electrically driven by means of an electric motor. The electric motor in the sense of the present application is used to convert electrical energy into mechanical energy and / or convert mechanical energy into electrical energy, and the electric motor generally includes a stationary part called the stator or armature and a part called the rotor that can move relative to the stationary part. In connection with the present invention, the electric motor can be particularly designed as a rotating machine. In the case of such an electric rotating machine, in particular, a distinction is made between a radial flux machine and an axial flux machine. The radial flux machine is characterized by the fact that the magnetic field lines formed in the air gap between the rotor and the stator extend in the radial direction, while in the case of the axial flux machine, the magnetic field lines formed in the air gap between the rotor and the stator extend in the axial direction. In the context of the present invention, an electric motor is provided, in particular for use in the powertrain of a hybrid or fully electric motor vehicle. In particular, the electric motor is dimensioned such that a vehicle speed greater than 50 km / h, preferably greater than 80 km / h, and in particular greater than 100 km / h can be achieved. Particularly preferably, the output of the electric motor is greater than 30 kW, preferably greater than 50 kW, and in particular greater than 70 kW. It is also preferred that the electric motor provides a speed greater than 5000 rpm, particularly preferably greater than 10,000 rpm, and most preferably greater than 12,500 rpm.

[0024] The electric motor may have a housing, also called a motor housing. The motor housing encloses the electric motor. The motor housing may also accommodate the control and power electronics unit, and preferably also at least part of the braking system. The motor housing may also be part of a cooling system for the electric motor, and the motor housing is designed such that the cooling fluid is fed to the electric motor via the motor housing and / or heat can be dissipated outward via the motor housing surface. In addition, the motor housing protects the electric motor and any electronics from external mechanical and / or chemical influences. The motor housing of the electric motor can be particularly made of a metallic material. Advantageously, the motor housing can be formed from a metallic casting material such as gray cast iron or cast steel. In principle, it is also conceivable that the motor housing is made entirely or partially of plastic. The motor housing of the electric motor can also be designed as a single piece or several parts.

[0025] The rotor is the rotating part of the electric motor. In particular, the rotor includes a rotor shaft and one or more rotor bodies formed by a rotor laminated core and arranged on the rotor shaft in a rotationally fixed manner. The rotor shaft can be hollow, which on the one hand results in weight reduction and on the other hand also allows the supply of lubricant or coolant to the rotor body. In particular, the rotor shaft can be coupled to the brake shaft of the braking system.

[0026] Preferably, the electric motor can be coupled to a transmission, and the electric motor is designed to generate a driving torque for a motor vehicle. The driving torque is particularly preferably the main driving torque, such that the motor vehicle is driven only by this driving torque.

[0027] In particular, the electric motor and the transmission can be arranged in a common powertrain housing. Alternatively, of course, the electric motor can also have a motor housing, and the transmission can of course also have a transmission housing. Thus, then, a structural unit can be achieved by fixing the transmission relative to the electric motor. This structural unit is sometimes also referred to as an electric axle. The powertrain housing is preferably made of a metallic material, particularly preferably made of aluminum, gray cast iron or cast steel, especially by means of a one-piece forming process, such as casting or die-casting. However, in principle, the powertrain housing can also be formed of plastic. In particular, the powertrain housing can preferably have a can-like basic shape, such that the electric motor and the transmission can be inserted into the powertrain housing via the open end face of the powertrain housing.

[0028] The electric motor preferably has a motor housing and / or the transmission has a transmission housing, wherein then a structural unit can be achieved by fixing the transmission relative to the electric motor. The transmission housing is a housing for accommodating the transmission. The task of the transmission housing is to guide the existing shafts via bearings and to provide the wheel (possibly a cam disk) with the degrees of freedom required under all loads and to absorb the bearing forces and support torques without impeding the rotation of the wheel and possible path movements of the wheel. The transmission housing can be single-shell or multi-shell, i.e., non-separated or separated. In particular, the transmission housing should be able to suppress noise and vibration and safely absorb hydraulic fluid. The transmission housing is preferably made of a metallic material, particularly preferably aluminum, gray cast iron or cast steel, especially by means of a one-piece forming process, such as casting or die-casting.

[0029] In addition, the transmission can preferably be configured as a planetary transmission or include a planetary transmission. The planetary transmission can preferably have a sun gear, a plurality of planet gears and a ring gear. The plurality of planet gears mesh with the sun gear, are rotatably mounted in a planet gear carrier and rotate around the sun gear. The ring gear is arranged coaxially relative to the sun gear, and the planet gears roll in the ring gear.

[0030] The drive may also have a differential drive. The differential drive is a planetary drive including a driver and two output parts. The differential drive generally has the following function: driving two wheels of a motor vehicle such that the wheels can rotate at different speeds in a curve, but with the same driving force.

[0031] In order to implement different drive or operation modes for a motor vehicle, one or more disengaging clutches may be provided in the torque path between the electric motor and the wheels. For example, a disengaging clutch may be arranged between the output part of the electric motor and the input part of the drive, such that the electric motor can be disconnected from the drive, thereby allowing the motor vehicle to operate in a coasting mode. It is also conceivable to arrange the disengaging clutch between the output part of the drive and one or more wheels, which also enables the coasting mode of the motor vehicle to be achieved. Finally, the disengaging clutch may also be arranged between the input part of the braking system and the output part of the electric motor, which allows the braking system to be completely disconnected from the electric motor.

[0032] For the purposes of the present application, a motor vehicle is a land vehicle that is moved by engine power and is not restricted by railway tracks. The motor vehicle may be selected, for example, from the group consisting of passenger cars, trucks, mopeds, light motor vehicles, motorcycles, buses and coaches or tractors.

[0033] Advantageous embodiments of the invention are specified in the claims formulated as dependent claims. The features listed individually in the claims formulated as dependent claims can be combined with each other in a technically useful manner and can define other embodiments of the invention. Additionally, the features indicated in the claims are explained and described in more detail in the description, which discloses other preferred embodiments of the invention.

[0034] According to an advantageous embodiment of the invention, the housing surface of the brake disc may have a circumferential housing surface section having a plurality of fluid guiding elements protruding radially from and / or radially into the housing surface.

[0035] The advantage of this embodiment is that the cooling capacity can be optimized by means of a suitable fluid guide. The fluid guiding elements

[0036] may be designed, for example, as rods extending in the axial direction. In principle, a blade-like design of the fluid guiding elements is also conceivable. The fluid guiding elements may also have brake disc cooling channels through which brake disc cooling fluid can flow.

[0037] In particular, the brake disc cooling channels can extend radially through the brake disc, such that a spoke-like configuration of the brake disc cooling channels is formed in the brake disc. Preferably, the brake disc cooling fluid is conveyed radially outwards through the brake disc cooling channels by centrifugal force. The cross-section of the brake disc cooling channels can have any profile. However, for manufacturing reasons, a circular profile and a rectangular profile are generally preferred.

[0038] According to a further preferred further improvement of the invention, the brake disc can also have a first circumferential annular element that projects radially outwards from the housing surface and that engages, with a clearance, in a corresponding first groove of the brake housing, and / or the brake disc can also have a second circumferential annular element that projects radially outwards from the housing surface and that engages, with a clearance, in a corresponding second groove of the brake housing.

[0039] This can provide a non-contact sealing element that separates or seals the "wet space" from the friction surface of the brake disc body relative to the brake caliper, to which the brake disc cooling fluid can be applied.

[0040] Furthermore, according to an equally advantageous embodiment of the invention, the first annular element and the second annular element can be arranged on a first axial side in a manner spaced apart from a housing surface section that includes a plurality of fluid guiding elements, such that an optimized separation between the "wet space" and the friction surface of the disc brake can be achieved.

[0041] According to another particularly preferred embodiment of the invention, the brake disc can have a third circumferential annular element that projects radially outwards from the housing surface and that engages, with a clearance, in a corresponding third groove of the brake housing, and / or the brake disc can have a fourth circumferential annular element that projects radially outwards from the housing surface and that engages, with a clearance, in a corresponding fourth groove of the brake housing.

[0042] In particular, this enables the effect of a further optimized separation between the "wet space" and the friction surface to be achieved.

[0043] Furthermore, the invention can also be further improved such that the third annular element and the fourth annular element are arranged on a second axial side in a manner spaced apart from a housing surface section that includes a plurality of fluid guiding elements, which also contributes to a further improvement in the separation between the "wet space" and the friction surfaces on the two end faces of the brake disc body.

[0044] In an equally preferred embodiment of the present invention, the fluid inlet can also be arranged in the bottom region of the brake housing in the direction of gravity, and / or the fluid outlet can also be arranged in the head region of the brake housing in the direction of gravity.

[0045] On the one hand, this enables the brake disc cooling fluid to flow out of the "wet space" or the brake housing under the influence of gravity, and / or on the other hand, enables the brake disc cooling fluid to escape under the influence of centrifugal force when the brake disc rotates in the head region of the brake housing.

[0046] It can also be advantageous to further improve the present invention such that the fluid inlet and the fluid outlet are connected to a brake disc cooling circuit, through which the brake disc cooling fluid that can be heated in the braking system can be fed to a heat exchanger, so that optimal cooling of the disc brake and / or further utilization of the friction-related waste heat of the disc brake can be achieved.

[0047] According to another preferred embodiment of the subject matter of the present invention, the brake disc can be arranged in a rotationally fixed manner on a rotatably mounted brake shaft, which is coupled to the rotor shaft of the rotor in a torque-transmitting manner. Among other things, this allows the mechanical braking effect of the braking system to be supported by the generator mode of the electric motor. This also makes it conceivable to use the electric motor to drive a frictionally connected braking system, so that the resulting frictional heat can be dissipated via the brake disc cooling fluid and fed through the heat exchanger for further use, for example, to heat the passenger compartment of the vehicle.

[0048] Finally, the present invention can also be advantageously designed such that an actuable first brake cylinder and an actuable second brake cylinder are accommodated in the brake housing, the first brake cylinder frictionally connects the first brake caliper in the brake caliper and the second brake cylinder frictionally connects the second brake caliper in the brake caliper to one of the end faces of the brake disc in each case, or releases the frictional connection with one of the end faces of the brake disc in each case. This has the advantage that the common brake caliper of the disc brake can be dispensed with, or - in other words - the brake housing takes over the function of the brake caliper.

[0049] It can also be preferred that the first annular element and the second annular element are substantially the same. Highly preferably, the first annular element and / or the second annular element is designed to be integral with the brake disc.

[0050] It is also preferred that the third annular element and the fourth annular element are designed to be substantially the same, where again, particularly preferably, the third annular element and / or the fourth annular element is designed to be integral with the brake disc.

[0051] In this context, it is also advantageous that the first annular element and the second annular element form a first labyrinth seal with the corresponding first groove and second groove. Preferably, the third annular element and the fourth annular element can also form a second labyrinth seal with the corresponding third groove and fourth groove.

[0052] Furthermore, it is particularly preferred that the first labyrinth seal and the second labyrinth seal are arranged axially spaced apart and define an annular space through which the brake disc cooling fluid can flow. Thus, this annular space forms a wet space within the brake housing, which separates the brake disc cooling fluid from the friction contact between the brake disc body and the brake caliper. Preferably, a circumferential housing surface section with a plurality of fluid guiding elements is axially enclosed by the first labyrinth seal and the second labyrinth seal. The fluid inlet and fluid outlet of the brake housing preferably lead to the annular space.

[0053] In a further preferred embodiment of the braking system, the brake shaft is rotatably mounted relative to the brake housing by means of a rolling bearing assembly arranged in the brake housing. The brake shaft is preferably sealed relative to the brake housing by means of a brake shaft seal. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The invention will now be explained in more detail with reference to the drawings without limiting the general concept of the invention.

[0055] In the drawings:

[0056] Figure 1 A schematic block diagram view of an electrically drivable motor vehicle with a braking system is shown;

[0057] Figure 2 A schematic axial sectional view of a motor vehicle braking system coupled to an electric motor is shown;

[0058] Figure 3 An axial sectional view of a braking system with a disc brake is shown;

[0059] Figure 4 An axial sectional view shows the Figure 3 detailed view of the head region of a known braking system;

[0060] Figure 5 An axial sectional view shows the Figure 3 detailed view of the bottom region of a known braking system. DETAILED DESCRIPTION

[0061] Figure 1 A braking system 1 of a motor vehicle 3 is shown, which can be electrically driven by means of an electric motor 2.

[0062] The braking system 1 includes a disc brake 4 having a brake disc 5 and a brake caliper 7 which can be frictionally connected to the brake disc 5 at the end face 6 of the brake disc, as can be seen clearly in Figure 2 The electric machine 2 accommodated in the motor housing 52 has a rotor 8 which is coupled in a torque-transmitting manner to at least one wheel 51 of the motor vehicle 3. In the Figure 2 embodiment shown, a transmission 54 is arranged in the torque path between the electric machine and the wheel 51, and the transmission can be decoupled from the torque path via a disengaging clutch 53, so that for example a coasting mode of the motor vehicle 3 can be achieved.

[0063] The electric machine 2, the transmission 54 and the disc brake 4 form a structural unit which is also referred to as an axle driveline 55.

[0064] The disc brake 4 is accommodated in a brake housing 9, and the brake disc 5 of the disc brake 4 is connected in a torque-transmitting manner to the rotor 8 of the electric machine 2. Figure 2 It is clearly shown that actuation of the disc brake 4 thus generates a braking torque in the torque path from the electric machine 2 to the wheel 51, whereby the wheel can be braked. The braking torque is thus generated via the brake disc 5, and two brake calipers 7 can act on the faces of the brake disc so as to counteract the axial forces. The axial forces are generated by two hydraulically connected hydraulic brake cylinders 26, 27, each of the hydraulic brake cylinders constituting a brake actuator. The hydraulic brake cylinders 26, 27 are pressurized with hydraulic fluid via a brake fluid passage 42.

[0065] The brake disc 5 is arranged in a rotationally fixed manner on a rotatably mounted brake shaft 24 which is coupled in a torque-transmitting manner to the rotor shaft 25 of the rotor 8, as mentioned above. The brake shaft 24 is rotatably mounted relative to the brake housing 9 by means of a rolling bearing assembly 38 arranged in the brake housing 9 and is sealed relative to the brake housing 9 by means of a brake shaft seal 39. Speed and torque can be introduced into the disc brake 4 from the corresponding splines of the rotor shaft 25 via splines 43 incorporated in the brake shaft 24. The brake shaft 24 is guided by the rolling bearing assembly 38. On the side of the brake shaft 24 on which the splines 43 for introducing speed and torque are arranged, the braking system 1 is sealed relative to the environment by means of a radially acting brake shaft seal 39.

[0066] In a brake housing 9, an actuatable first brake cylinder 26 and an actuatable second brake cylinder 27 are received. The first brake cylinder 26 frictionally connects a first brake caliper in the brake caliper 7 and the second brake cylinder 27 frictionally connects a second brake caliper in the brake caliper 7 to one of the end faces 6 of the brake disc 5 in each case, or releases the frictional connection to one of the end faces 6 of the brake disc 5 in each case. In order to generate a braking torque, two opposing brake caliper friction linings 41 are thus each arranged at the end face 6 on a movable brake caliper body 40. The brake caliper friction linings 41 are located in the upper region as viewed along the axis of the brake shaft 24. The required displacement and axial force are generated by means of two hydraulic brake cylinders 26, 27 having seals 50 with a rectangular cross-section. The groove geometry in which the seal 50 is arranged with a rectangular cross-section is designed such that wear is self-adjusting. In the non-actuated state, the movable brake caliper body 40 is moved into a predetermined starting position by means of one or more spring elements 46 under spring force. In this case, the movable brake caliper body 40 is axially guided via pin-shaped guide elements 45, 47. End stops 48 are also formed in this region, and the end stops delimit the axial travel of the brake caliper body 40.

[0067] The brake disc 5 has a hydraulic brake disc cooling system 10 in which a brake disc cooling fluid 12 can be applied to the shell surface 11 of the brake disc 5 and can be introduced through a fluid inlet 13 of the brake housing 9 and discharged from the brake housing via a fluid outlet 14 of the brake housing 9. The fluid inlet 13 is arranged in the bottom region 20 of the brake housing 9 in the direction of gravity, and the fluid outlet 14 is arranged in the head region 21 of the brake housing 9 in the direction of gravity. The fluid inlet 13 and the fluid outlet 14 are connected to a brake disc cooling circuit 22, and the brake disc cooling fluid 12 that can be heated in the brake system 1 can be fed to a heat exchanger 23 via this brake disc cooling circuit. Water or a mixture of water and another substance (for example, a water-glycol mixture) is used as the brake disc cooling fluid 12 for heat dissipation.

[0068] The shell surface 11 of the brake disc 5 has a circumferential shell surface section 30 which has a plurality of fluid guiding elements 15 that project radially from the shell surface 11 and / or project radially into the shell surface 11. In the illustrated embodiment, the fluid guiding elements 15 are designed as rods extending in the axial direction. Compared with brake discs having an internal geometry known from the prior art, no holes are arranged in the end face 6 of the brake disc 5, so that the brake disc cooling fluid 12 cannot axially pass through the brake disc 5 in the direction of the friction-loaded outer surface of the brake disc 5.

[0069] Figures 3 to 5It is also clearly shown in combination that the brake disc 5 has a first circumferential annular element 16 which projects radially outwards from the housing surface 11 and which engages, with play, in a corresponding first groove 17 of the brake housing 9. Furthermore, the brake disc 5 has a second circumferential annular element 18 which projects radially outwards from the housing surface 11 and which engages, with play, in a corresponding second groove 19 of the brake housing 9.

[0070] As Figures 3 to 5 shown, the first annular element 16 and the second annular element 18 are arranged on the first axial side 33 in a spaced-apart manner from a housing surface section 30 which includes a plurality of fluid guiding elements 15.

[0071] Figures 3 to 5 It is also shown that the brake disc 5 has a third circumferential annular element 28 which projects radially outwards from the housing surface 11 and which engages, with play, in a corresponding third groove 29 of the brake housing 9, and / or finally, the brake disc 5 also has a fourth circumferential annular element 31 which projects radially outwards from the housing surface 11 and which engages, with play, in a corresponding fourth groove 32 of the brake housing 9. The third annular element 28 and the fourth annular element 31 are arranged on the second axial side 34 in a spaced-apart manner from a housing surface section 30 which includes a plurality of fluid guiding elements 15.

[0072] The first annular element 16 and the second annular element 18 are designed to be substantially identical and integral with the brake disc 5. This also applies to the third annular element 28 and the fourth annular element 31, which are also designed to be substantially identical and integral with the brake disc 5.

[0073] The first annular element 16 and the second annular element 18 together with the corresponding first groove 17 and second groove 19 form a first labyrinth seal 35, and the third annular element 28 and the fourth annular element 31 together with the corresponding third groove 29 and fourth groove 32 form a second labyrinth seal 36. The first labyrinth seal 35 and the second labyrinth seal 36 are arranged axially spaced apart and define an annular space 37 through which the brake disc cooling fluid 12 can flow. Thus, the annular space 37 can also be described as a "wet space". The circumferential housing surface section 30 which includes a plurality of fluid guiding elements 15 is axially enclosed by the first labyrinth seal 35 and the second labyrinth seal 36. The fluid inlet 13 and the fluid outlet 14 of the brake housing 9 lead to the annular space 37.

[0074] The brake disc cooling fluid 12 is fed into the annular space 37 via the distributor geometry 44 for fluid guiding and distribution of the brake disc 5. Two labyrinth seals 35, 36 are arranged in the brake disc 5 to prevent the fluid flow from flowing in the direction of the end face 6 of the brake disc 5.

[0075] At the lowest point of the brake disc 5 relative to the ground center, a collector geometry 49 is formed. The collector geometry is designed such that the inclined geometry guides the brake disc cooling fluid 12 in the direction of the fluid inlet 13 by means of gravity. Here, the annular elements 18, 31 protruding radially outward from the brake disc 5 protrude into the inclined part of the collector geometry 49.

[0076] The present invention is not limited to the embodiments shown in the drawings. Therefore, the above description should not be considered restrictive, but rather illustrative. The appended claims should be understood to mean that the stated features exist in at least one embodiment of the present invention. This does not exclude the existence of other features. In the case where the claims and the above description define a "first" feature and a "second" feature, such naming is used to distinguish between two features of the same type and does not define a priority order.

[0077] List of reference numerals

[0078] 1 Brake system

[0079] 2 Electric motor

[0080] 3 Motor vehicle

[0081] 4 Disc brake

[0082] 5 Brake disc

[0083] 6 End face

[0084] 7 Brake caliper

[0085] 8 Rotor

[0086] 9 Brake housing

[0087] 10 Brake disc cooling system

[0088] 11 Shell surface

[0089] 12 Brake disc cooling fluid

[0090] 13 Fluid inlet

[0091] 14 Fluid outlet

[0092] 15 Fluid guiding element

[0093] 16 Annular element

[0094] 17 Groove

[0095] 18 Ring element

[0096] 19 Groove

[0097] 20 Bottom region

[0098] 21 Head region

[0099] 22 Brake disc cooling circuit

[0100] 23 Heat exchanger

[0101] 24 Brake shaft

[0102] 25 Rotor shaft

[0103] 26 Brake cylinder

[0104] 27 Brake cylinder

[0105] 28 Ring element

[0106] 29 Groove

[0107] 30 Housing surface section

[0108] 31 Ring element

[0109] 32 Groove

[0110] 33 Side

[0111] 34 Side

[0112] 35 Labyrinth seal

[0113] 36 Labyrinth seal

[0114] 37 Annular space

[0115] 38 Rolling bearing assembly

[0116] 39 Brake shaft seal

[0117] 40 Brake caliper body

[0118] 41 Brake caliper friction lining

[0119] 42 Brake fluid passage

[0120] 43 Spline

[0121] 44 Distributor geometry

[0122] 45 Guide pin

[0123] 46 Spring element

[0124] 47 Guide element

[0125] 48 End stop

[0126] 49 Collector geometry

[0127] 50 Seal

[0128] 51 Wheel

[0129] 52 Motor housing

[0130] 53 Disengaging clutch

[0131] 54 Transmission

[0132] 55 Axle drive system.

Claims

1. A braking system (1) of a motor vehicle (3) that can be electrically driven by means of an electric machine (2), wherein, The brake system (1) includes a disc brake (4) having a brake disc (5) and a brake caliper (7) which can be frictionally connected to the brake disc (5) at the end face (6) of the brake disc, and the electric motor (2) has a rotor (8) which is torque-transmittingly coupled to at least one wheel (51) of the motor vehicle (3). It is characterized in that the disc brake (4) is received in a brake housing (9), and the brake disc (5) of the disc brake (4) is torque-transmittingly connected to the rotor (8) of the electric motor (2), and the brake disc (5) has a hydraulic brake disc cooling system (10) in which a brake disc cooling fluid (12) can be applied to the shell surface (11) of the brake disc (5) and can be introduced through a fluid inlet (13) of the brake housing (9) and can be discharged from the brake housing via a fluid outlet (14) of the brake housing (9).

2. The brake system (1) according to claim 1, It is characterized in that the shell surface (11) of the brake disc (5) has a circumferential shell surface section (30) which has a plurality of fluid guiding elements (15) protruding radially from and / or radially protruding into the shell surface (11).

3. The brake system (1) according to claim 1 or 2, It is characterized in that the brake disc (5) has a first circumferential annular element (16) which protrudes radially outward from the shell surface (11) and which engages in a corresponding first groove (17) of the brake housing (9) with a clearance, and / or the brake disc (5) has a second circumferential annular element (18) which protrudes radially outward from the shell surface (11) and which engages in a corresponding second groove (19) of the brake housing (9) with a clearance.

4. The brake system (1) according to claim 3, It is characterized in that the first annular element (16) and the second annular element (18) are arranged on a first axial side (33) in a spaced-apart manner from the shell surface section (30) having a plurality of fluid guiding elements (15).

5. The brake system (1) according to claim 3 or 4, It is characterized in that The brake disc (5) has a third circumferential annular element (28) that projects radially outward from the housing surface (11) and engages with a corresponding third groove (29) of the brake housing (9) with a clearance, and / or the brake disc (5) has a fourth circumferential annular element (31) that projects radially outward from the circumferential surface (11) and engages with a corresponding fourth groove (32) of the brake housing (9) with a clearance.

6. The brake system (1) according to claim 5, characterized in that the third annular element (28) and the fourth annular element (31) are arranged on the second axial side (34) in a spaced-apart manner from the housing surface section (30) having a plurality of fluid guiding elements (15).

7. The brake system (1) according to any one of the preceding claims, characterized in that the fluid inlet (13) is arranged in the bottom region (20) of the brake housing (9) in the direction of gravity, and / or the fluid outlet (14) is arranged in the head region (21) of the brake housing (9) in the direction of gravity.

8. The brake system (1) according to claim 7, characterized in that the fluid inlet (13) and the fluid outlet (14) are connected to a brake disc cooling circuit (22), and the brake disc cooling fluid (12) that can be heated in the brake system (1) can be fed to a heat exchanger (23) via the brake disc cooling circuit.

9. The brake system (1) according to any one of the preceding claims, characterized in that the brake disc (5) is arranged in a rotationally fixed manner on a rotatably mounted brake shaft (24), and the brake shaft is coupled to the rotor shaft (25) of the rotor (8) in a torque-transmitting manner.

10. The brake system (1) according to any one of the preceding claims, characterized in that a first actuable brake cylinder (26) and a second actuable brake cylinder (27) are accommodated in the brake housing (9), and the first brake cylinder (26) frictionally connects a first brake caliper in the brake caliper (7) and the second brake cylinder (27) frictionally connects a second brake caliper in the brake caliper (7) to one of the end faces (6) of the brake disc (5) in each case, or releases the frictional connection with one of the end faces (6) of the brake disc (5) in each case.

Images