Electric motor system and vehicle with the same

Abstract

Electric motor system (1) comprising: a housing (10); a drive shaft (20) rotatably mounted to rotate relative to the housing (10); an electric motor (30) installed in the housing (10) comprising a motor stator (31) attached to the housing (10) and a motor rotor (33) mounted on the drive shaft (20) to rotate relative to the motor stator (31);a brake arrangement (40) comprising a brake rotor (43) mounted on the drive shaft (20) within the housing (10) to rotate relative to the housing (10), the brake arrangement (40) further comprising a brake stator (41) with a brake pad (42) configured to be pressed against the brake rotor (43), the brake rotor (43) being adjacent to the motor rotor (33) to allow heat conduction from the brake rotor (43) to the motor rotor (33), the motor rotor (33) and the brake rotor (43) each having a contact surface extending around the drive shaft (20), the contact surface of the brake rotor (43) being adjacent to the contact surface of the motor rotor (33).

Description

Field of invention The present disclosure relates to an electric motor system and a vehicle comprising such an electric motor system, for example an electric vehicle or a hybrid vehicle. Background of the invention Electric and hybrid vehicles generally include at least one electric motor to generate torque to drive the vehicle's wheels. Typically, the electric motor is part of the vehicle's electric drive system, which may include other components to transmit torque from the electric motor to the vehicle's wheels, such as a transmission, drive shafts, and differentials. The vehicle may also include components for cooling the electric motor and other parts of the electric drive system, such as water cooling, air cooling, or oil cooling. To decelerate the vehicle, the motor can also be used as a generator to convert at least some of the vehicle's kinetic energy into electrical energy. The energy recovered in this way can be stored in the vehicle's battery.Conventional friction brakes are mounted on the vehicle's wheels to either supplement the braking force generated by the engine or to provide the entire braking force in the event of an engine failure. Examples of friction brakes include caliper brakes and disc brakes. From DE 10 2004 033 745 A1, an arrangement is known which comprises a housing, a drive shaft rotatably mounted to rotate relative to the housing, an electric motor installed in the housing and comprising a motor stator attached to the housing and a motor rotor mounted on the drive shaft to rotate relative to the motor stator, as well as a brake arrangement comprising a brake rotor mounted on the drive shaft inside the housing to rotate relative to the housing, wherein the brake arrangement also comprises a brake stator with a brake lining configured to be pressed against the brake rotor, the brake rotor being adjacent to the motor rotor. An objective of the present invention is to improve known electric motors and braking systems for electric and hybrid vehicles in a way that helps to reduce the weight and cost of such a motor and braking system. Furthermore, it is desirable to reduce the environmental impact of such systems, for example by reducing air pollution from brake abrasion particles. demolition The aforementioned objectives are achieved according to the present invention by an integrated electric motor system according to claim 1 and by a vehicle with such an electric motor system, such as an electric or hybrid vehicle. Various embodiments of the invention are set forth in the dependent claims and the following description. An electric motor system according to the invention comprises a housing and a drive shaft or axle rotatably mounted to rotate relative to the housing. The electric motor system includes an electric motor installed inside the housing. The electric motor comprises a motor stator attached to the housing and a motor rotor mounted on the drive shaft to rotate relative to the motor stator. The electric motor system also includes a brake assembly with a brake rotor mounted on the drive shaft inside the housing to rotate relative to the housing. The brake assembly further comprises a brake stator with a brake pad configured to be pressed against the brake rotor by means of a brake actuator. The brake rotor is adjacent to the motor rotor to facilitate heat transfer between them. In this way, frictional heat generated by applying the brakes is transferred from the brake rotor to the motor rotor, which then acts as a heat reservoir to store at least some of the braking energy and cool the brake rotor. The frictional heat generated by the brakes and transferred to the electric motor can be removed from the electric motor system in the same way—and in some cases, by the same cooling components—as the heat generated by the electric motor itself. As described in more detail below, the electric motor system may include components for cooling the electric motor system or may be connected to a cooling system for cooling the electric motor system. This cooling system may be part of the vehicle's powertrain cooling system. As described above, the electric motor of the electric motor assembly can be used as a generator to convert at least some of the vehicle's kinetic energy into electrical energy. The brake assembly can therefore be used primarily to supplement the braking force generated by the motor and can thus be smaller compared to conventional friction brakes in vehicles without regenerative braking. The inventors have found that it is therefore possible to integrate the brake assembly, or at least the brake rotor of the brake assembly, into the same housing as the electric motor without significantly increasing the dimensions of the housing used to house the motor alone.For example, it may be sufficient to enlarge the housing axially to accommodate the brake rotor in addition to the electric motor, since the brake rotor can have essentially the same diameter as the motor rotor. Furthermore, because the brake assembly can be used primarily to supplement the braking force of the electric motor, less frictional heat can be generated compared to the amount of frictional heat produced by conventional friction brakes in vehicles without regenerative braking. It is therefore often possible to use essentially the same cooling system that was previously used to cool the electric motor alone. Furthermore, since the brake rotor, which has a friction surface against which the brake pad is pressed for braking, is housed in the casing, any abrasion originating from the friction surface or from the brake pad pressed against the friction surface is generated within the casing and can therefore be completely or at least partially captured within the casing, thus reducing or preventing contamination of the air with the aforementioned abrasion. In some embodiments, the motor rotor and the brake rotor can each have a contact surface that extends around the drive shaft. The contact surface of the brake rotor can be adjacent to the contact surface of the motor rotor, thus enabling heat conduction from the contact surface of the brake rotor directly to the adjacent contact surface of the motor rotor. Both of these contact surfaces can be annular and each have an inner diameter and an outer diameter. In some embodiments, the inner diameters can be approximately the same (within a relative difference of 5%) or identical. In some examples, the contact surfaces are flat. In some examples, the contact surfaces are oriented perpendicular to a longitudinal axis of the drive shaft.To promote heat conduction, the contact surfaces are as large as possible. In some embodiments, the outer diameters of these contact surfaces are at least 90% or at least 95% of the inner diameter of a lateral housing inner wall region that radially surrounds the motor rotor and the brake rotor. In some embodiments, the inner diameters of the aforementioned contact surfaces are no more than a factor X larger than an outer surface of the drive shaft (for example, a surface of a rod-shaped body of the drive shaft), where X is less than 3, less than 2, or even less than 1.5. In some embodiments, the brake rotor and the motor rotor are connected to each other in a rotationally fixed manner. This allows torque generated by the electric motor to be transferred from the motor rotor to the brake rotor, thereby accelerating the rotation of the brake rotor, for example. Conversely, torque generated by the braking mechanism (when the brake pad is pressed against the rotating brake rotor) can be transferred to the motor rotor, thereby slowing its rotation, for example. The brake rotor and the motor rotor can be connected to each other by a weld, a solder joint, or an adhesive bond to create a rotationally fixed connection. In some embodiments, a rotationally fixed connection can be achieved by connecting the aforementioned contact surfaces by means of a weld, a solder joint, or an adhesive bond.Additionally or alternatively, the brake rotor and the motor rotor can be connected to each other by means of bolts. In such embodiments, the motor rotor and the brake rotor rotate at the same speed around the longitudinal axis of the drive shaft when they are rotating. In some embodiments, the motor rotor and the brake rotor can each comprise a central section, each of which has a central opening, the drive shaft passing through the respective central openings of the brake rotor and motor rotor central sections. For example, the motor rotor and brake central sections can form the respective contact surfaces of the motor rotor and brake rotor mentioned above. The central sections can extend radially outward relative to the drive shaft toward an inner housing wall. The central sections can be disc-shaped or annular. The central sections can have identical or approximately identical (up to a relative difference of 5%) outer diameters. In some embodiments, the motor rotor may have a peripheral part extending from an outer circumference of the central part of the motor rotor in a direction away from the brake rotor, for example, in an axial direction relative to the drive shaft. At least one permanent magnet of the motor rotor may be attached to the peripheral part of the motor rotor. In some embodiments, the peripheral part of the motor rotor may be cylindrical. In some embodiments, the motor rotor may be cup-shaped or drum-shaped. The permanent magnet of the motor rotor is typically located opposite the motor stator and a stator winding supported by the motor stator at a predetermined distance. In some embodiments, the brake rotor may include a peripheral portion extending from an outer diameter of the central portion of the brake rotor in a direction away from the motor rotor, for example, in an axial direction parallel to the drive shaft. The brake lining may be configured to be pressed against the peripheral portion, for example, against a friction surface on the peripheral portion of the brake rotor. In some embodiments, the peripheral portion of the brake rotor may be cylindrical. In some embodiments, the brake rotor may be cup-shaped or drum-shaped. In some embodiments, the brake assembly may be a drum brake assembly.The friction surface can be located on a radially inner surface of the peripheral part of the brake rotor, and the at least one brake pad can be configured to move in a radially outward direction (by means of an actuator of the brake assembly) to be pressed against the friction surface. In such embodiments, the brake assembly can be an internal shoe brake or an external shoe brake. In other embodiments, the brake assembly can be a disc brake assembly, for example, a partial disc brake or a full disc brake. In some embodiments, the peripheral part can be disc-shaped and extend radially from the central part of the brake rotor. In such embodiments, the actuator of the brake assembly can have one or more brake calipers to press the brake pads against the disc-shaped brake rotor. In some embodiments, the electric motor may have a first bearing arrangement that is radially arranged between the drive shaft and the motor rotor and configured to rotatably mount the motor rotor on the drive shaft. Alternatively or additionally, the first bearing arrangement may be at least partially aligned with the central openings of the motor rotor and the brake rotor. The first bearing arrangement may include a ball bearing. The first bearing arrangement may be configured to allow rotation of the drive shaft relative to the motor rotor and the brake rotor.The first bearing arrangement can be configured to allow axial movement (displacement) of the drive shaft, particularly relative to the rotor motor, brake rotor, brake stator, motor stator, motor stator carrier (described below) and the housing. In some embodiments, the drive shaft can comprise a rod-shaped body or main body extending from a first end part of the drive shaft to a second end part of the drive shaft, and a support part extending radially from the main body of the drive shaft. For example, the support part can be disc-shaped. The support part can have at least one first connecting element on a side facing the brake rotor. The brake rotor can have at least one second connecting element on a side facing the support part of the drive shaft.The drive shaft can be axially displaceable relative to the housing and relative to the brake rotor (and additionally relative to the motor rotor and the housing) between a first axial position in which the support part is adjacent to the brake rotor and a second axial position in which the support part is separated from the brake rotor, wherein the at least one first connecting element is configured to couple with the at least one second connecting element when the drive shaft is in the first axial position to establish a rotationally fixed connection between the drive shaft and the brake rotor. In embodiments in which the brake rotor and the motor rotor are connected to each other in a rotationally fixed manner, a rotationally fixed connection between the drive shaft and the brake rotor means that the drive shaft and the motor rotor are also connected to each other in a rotationally fixed manner.It is understood that in such embodiments, the displacement of the drive shaft between the first and second axial positions makes it possible to connect the electric motor and the brake assembly to the drive shaft in order to transmit torque to the drive shaft in order to accelerate (by means of the electric motor) the rotation of the drive shaft or (by means of the brake assembly) to decelerate the rotation of the drive shaft. For example, for each stop of the electric motor required when the motor's electric braking function is out of operation, the drive torque of the rotor can be reduced by pressing the brake pad against the friction surface of the brake rotor by means of the actuator of the brake assembly. In some embodiments, the electric motor may also include a stator carrier and a second bearing arrangement mounted on the drive shaft to rotatably support the stator carrier on the drive shaft. The stator carrier may be arranged radially between the motor stator and the drive shaft. The second bearing arrangement may also be arranged radially between the stator carrier and the drive shaft. The second bearing arrangement may include a ball bearing. The second bearing arrangement may be configured to allow axial movement (displacement) of the drive shaft, particularly relative to the motor rotor, brake rotor, brake stator, motor stator, motor stator carrier, and housing. In some embodiments, the motor stator carrier may be configured to cool the motor stator, for example, as described in more detail below. As mentioned above, in some embodiments the brake assembly may include at least one brake actuator coupled to the housing and configured to press the at least one brake pad against a friction surface of the brake rotor. The at least one actuator may, for example, include one or more electric motors or hydraulic power sources to selectively move the brake pads toward or away from the friction surfaces of the brake rotor. The actuator may have one or more drive elements, each connected to one of the at least one brake pads to move the brake pads relative to the friction surface of the brake rotor. Alternatively, the actuator may have a brake caliper to which the at least one brake pad is attached and which is configured to move the one or more brake pads relative to the friction surface of the brake rotor. A vehicle according to the invention comprises an electric motor system as described herein. The vehicle can be an electric vehicle or a hybrid vehicle. The motor system can be integrated into a drive system of the vehicle, as described above. The vehicle can include a cooling system configured to cool the electric motor system, thereby cooling both the electric motor and the brake assembly of the electric motor system. Detailed description In the following, embodiments of the present invention are described in more detail with reference to the figures, which show: Fig. 1 a perspective view of an embodiment of an electric motor system according to the invention, Fig. 2 a view of a cross-section through the embodiment shown in Fig. 1, and Fig. 2A a view of a cross-section through a part of the embodiment shown in Fig. 1 and Fig. 2 along the dashed line shown in Fig. 2. Figures 1, 2, and 2A show an embodiment of an electric motor system 1 according to the invention. The electric motor system 1 comprises a housing 10, a drive shaft or axle 20 which is rotatably mounted to rotate about a longitudinal axis (indicated by a thin dashed line in Figure 2) of the drive shaft 20 relative to the housing 10. The electric motor system 1 also comprises an electric motor 30 which is installed inside the housing 10. The electric motor 30 comprises a motor stator 31 which is attached to the housing 10, for example, by means of bolts. The motor stator 31 supports a stator winding 31' of the electric motor 30. The electric motor 30 also comprises a motor rotor 33 which is mounted on the drive shaft 20 to rotate relative to the motor stator 31. The motor rotor 33 carries permanent rotor magnets 33' of the electric motor 30. The electric motor system 30 also includes a brake assembly 40, which has a brake rotor 43 mounted inside the housing 10 on the drive shaft 20 to rotate relative to the housing 10. The brake assembly 40 also includes a brake stator 41 with a brake pad 42 configured to be pressed against a friction surface 43' of the brake rotor 43. The brake assembly includes a brake actuator 44, which is coupled to the housing 10 and configured to move the brake pad 42 relative to the housing 10 and relative to the brake rotor 43 and to press the brake pad 42 against the friction surface 43'. The brake assembly 40 also includes, for example, one or more electric motors 45 coupled to the brake actuator 44 to drive the brake actuator 44 to move the brake pad 42 towards or away from the friction surface 43' of the brake rotor 43. The brake rotor 43 is adjacent to and in contact with the motor rotor 33 to allow heat conduction from the brake rotor 43 to the motor rotor 44. In this way, frictional heat generated when the brake assembly is actuated is conducted from the brake rotor 43 to the motor rotor 33, which thus acts as a heat reservoir, storing at least some of the frictional heat generated when the brake pad 42 is pressed against the friction surface 43' of the brake rotor 43 as the latter rotates. The electric motor system 1 can also include a cooling arrangement, such as an oil bath (not shown). Alternatively or additionally, the electric motor system 1 can be connected to a cooling system of a vehicle's drive system (not shown), into which the electric motor system 1 may be integrated. Examples of cooling systems include water cooling systems, air cooling systems, and oil cooling systems. The latter can, for example, include an oil bath of the drive system. Thus, the frictional heat generated by the brake arrangement 40 and conducted to the electric motor 30 as described above can first be (temporarily) stored by the motor rotor 33 and then finally dissipated from the electric motor system 1 in the same way as the frictional heat generated by the electric motor itself, by means of the aforementioned cooling arrangements or cooling systems.For example, the heat generated by the brake assembly 40 and the electric motor 30 can be used to heat the driver / passenger compartment of the vehicle, for example by means of a heat exchanger of the vehicle. Since the brake rotor 43 and its friction surface 31 are housed in the casing 10, any abrasion originating from the friction surface 31' or the brake pad 42 is generated within the casing 10 and remains contained therein. In this way, contamination of the air with said abrasion can be avoided or at least reduced. In the exemplary embodiment, the housing 10 has several wall parts that enclose an interior of the housing, for example a cup-shaped first wall part 11, a cylindrical or annular second wall part 12, and a plate-shaped third wall part 13. The housing comprises a first opening 14 arranged in the first wall part 11 and a second opening 15 arranged in the third wall part 13, wherein the drive shaft 20 passes through the first opening 11, through the interior of the housing 10, and through the second opening 13. As shown in Fig. 2 and Fig. 2A, the brake actuator 44 is attached to an outer surface of the housing 10, for example, to a portion of the outer surface of the second wall section 12. As shown in Fig. 2A, the brake actuator 44 comprises a movable rod-shaped drive element 49, which extends through an opening in the wall section 12 into the interior of the housing 10, where a distal end of the drive element 49 is coupled to the brake pad 42. A proximal end of the drive element 49 is connected to the electric motor 45 of the brake assembly 40. When the brake assembly 40 is actuated to decelerate the rotational movement of the brake rotor 43, the electric motor 45 is activated to generate a force that is transmitted via the drive element 49 to the brake pad 42 to press the brake pad 42 against the friction surface 43' of the brake rotor 43. While in the illustrated embodiment the brake assembly 40 comprises only one brake pad 42, one brake actuator 44, and one electric motor 45, it would also be possible for the brake assembly 40 to comprise more than one brake pad 42, more than one brake actuator 44, and / or more than one electric motor 45. For example, two or more brake pads 42, brake actuators 44, and electric motors 45 could be distributed over the second wall section 12 of the housing 10 such that they are arranged around the brake rotor 43 on two or more opposite sides. As shown in Fig. 2, the motor rotor 33 and the brake rotor 43 each have a contact surface extending around the drive shaft 20. The contact surface of the brake rotor 43 adjoins the contact surface of the motor rotor 33, thus enabling heat conduction from the contact surface of the brake rotor 43 directly to the adjacent contact surface of the motor rotor 43. In this example, both contact surfaces are flat and annular, each with an inner diameter and an outer diameter. In this example, the inner and outer diameters are identical. The contact surfaces are oriented perpendicular to a longitudinal axis of the drive shaft and extend radially towards an inner wall of the housing 10.For example, the outer diameters of the aforementioned contact surfaces can be at least 90% or at least 95% of the inner diameter of a lateral housing inner wall region that radially surrounds the motor rotor 33 and the brake rotor 43. Furthermore, the inner diameters of the aforementioned contact surfaces can be less than a factor X larger than an outer surface of the drive shaft (for example, an outer surface of a rod-shaped body of the drive shaft), where X can be less than 3, less than 2, or even less than 1.5. In the example shown, the brake rotor 43 and the motor rotor 33 are connected to each other in a rotationally fixed manner. In this way, a torque generated by the electric motor 30 can be transmitted from the motor rotor 33 to the brake rotor 43, which can, for example, accelerate the rotational movement of the brake rotor 43. Furthermore, a torque generated by the brake assembly 40 (when the brake pad 42 is pressed against the rotating brake rotor 43) can be transmitted from the brake rotor 43 to the motor rotor 33, which can, for example, decelerate the rotational movement of the motor rotor 33, such as in cases where a braking function of the electric motor fails. To create the aforementioned rotationally fixed connection between the brake rotor 43 and the motor rotor 33, the brake rotor 43 can be connected to the motor rotor 33, for example, by means of a weld, a soldered connection, or an adhesive bond, such as by connecting the contact surfaces of the brake rotor 43 and the motor rotor 33 using such a connection. Alternatively or additionally, the brake rotor and the motor rotor can be connected to each other using bolts. In the present embodiment, the brake rotor 43 and the motor rotor 33 each have a central section 46, 36. Each of the central sections has a central opening, as shown in Fig. 2. The drive shaft 20 passes through the respective central openings of the central sections 46, 36 of the brake rotor 43 and the motor rotor 34. In this example, the central sections 46, 36 of the motor rotor 43 and the brake rotor 43 form the contact surfaces of the motor rotor 43 and the brake rotor 44. As shown in Fig. 2, the central sections 36, 46 are disc-shaped and extend radially outward relative to the drive shaft 20 toward an inner wall of the housing 10. In the example shown, the central sections 36, 46 have approximately identical inner and outer diameters. In the example shown, the motor rotor 33 has a peripheral part 37 that extends from an outer circumference of the central part 36 of the motor rotor 33 in an axial direction relative to the drive shaft 10, pointing away from the brake rotor 43. The at least one permanent magnet 33' of the motor rotor 33 is attached to the peripheral part 37 of the motor rotor 33, for example, on a radially inner surface of the peripheral part 37, facing the motor stator 31 and the stator winding 31' mounted thereon at a predetermined distance. In the embodiment shown, the peripheral part 37 of the motor rotor 33 has a cylindrical shape, so that the motor rotor 33 is cup-shaped. Similar to the motor rotor 33, the brake rotor 43 in the present embodiment also has a peripheral part 47 that extends from an outer circumference of the central part 46 of the brake rotor 43 in a direction away from the motor rotor 33 and in an axial direction parallel to the drive shaft 10. The friction surface 43' is arranged on a radially outer surface of the peripheral part 47, and the brake pad 42 is configured to be pressed against the peripheral part 47 in a radially inward direction by means of the brake actuator 44, which is driven by the electric motor 45 of the brake assembly 40. As mentioned above, in alternative embodiments the electric motor 45 can be replaced by a hydraulic motor or a hydraulic pressure source. In the embodiment shown, the peripheral part 47 of the brake rotor has a cylindrical shape, so that the brake rotor 43 is cup-shaped or drum-shaped.In the illustrated embodiment, the brake assembly 40 thus forms a drum brake assembly. In an alternative embodiment, the friction surface 43' can be arranged on a radially inner surface of the peripheral part 47, and the at least one brake lining 442 can then be configured to move in a radially outer direction. In such a configuration, the brake actuator 44 and / or the electric motor 45 of the brake assembly 40 can be arranged completely or at least partially within the housing 10. In alternative embodiments, the brake arrangement 40 can be configured as a disc brake arrangement. In such embodiments, the peripheral part 47 can be disc-shaped and extend radially from the central part 46 of the brake rotor 43, and the actuator can comprise a brake caliper on which the at least one brake pad 42 is attached as described above. In the exemplary embodiment shown, the electric motor system 1 comprises a first bearing arrangement 51, which is arranged radially between the drive shaft 10 and the motor rotor 33 and is configured to rotatably mount the motor rotor 33 on the drive shaft 10. The first bearing arrangement 51 also extends radially between the drive shaft 10 and the brake rotor 43 and is configured to rotatably mount the brake rotor 43 on the drive shaft 10 as well. The first bearing arrangement 51 is therefore located within the aforementioned central openings of the central sections 36, 46 of the motor rotor 31 and the brake rotor 46. In the illustrated embodiment, the first bearing unit 51 comprises a ball bearing. The first bearing arrangement is configured to allow rotation of the drive shaft 10 relative to the motor rotor 33 and the brake rotor 43.The first bearing arrangement 51 is also configured to allow axial movement (displacement) of the drive shaft 10 relative to the motor rotor 33, the brake rotor 43, the brake stator 41, the motor stator 31, the (above described) motor stator carrier 48 and the housing 10. In the exemplary embodiment shown, the drive shaft 10 comprises a rod-shaped body or main body 20' extending axially from a first end part 21 of the body 20' to a second end part 22 of the body 20'. The drive shaft 20 also comprises a support part 23 extending radially from the body 20'. In this example, the support part 23 is disk-shaped. The support part 23 includes at least one first connecting element 24 on a side facing the brake rotor 43. The brake rotor 43 includes at least one second connecting element 48 on a side facing the support part 23 of the drive shaft 20.As described above, the drive shaft 20 is axially displaceable, in particular relative to the brake rotor 43 (and additionally relative to the motor rotor 33 and the housing 10) between a first axial position (not shown), in which the support part is adjacent to and contacts the brake rotor, and a second axial position (as shown in Fig. 2), in which the support part 23 is separated from the brake rotor 43. The at least one first connecting element 24 is configured to connect to the at least one second connecting element 48 when the drive shaft 10 is in the first axial position. For example, the at least one first connecting element may have one or more projections or extensions extending in an (axial) direction from the support part 23 to the brake rotor 43. Furthermore, the at least one second connecting element 48 may have one or more holes or recesses in the brake rotor 43, arranged and configured to receive the aforementioned one or more projections or extensions of the at least one first connecting element 24 when the drive shaft 10 is in the first axial position.Alternatively or additionally, the at least one second connecting element 48 can have one or more projections or extensions extending in an (axial) direction from the brake rotor 43 to the support part 23. Furthermore, the at least one first connecting element 24 can have one or more holes or recesses in the support part 23, arranged and configured to receive the aforementioned one or more projections or extensions of the at least one second connecting element 48 when the drive shaft 10 is in the first axial position. In the first axial position, the drive shaft 10 and the brake rotor 43 are connected to each other in a rotationally fixed manner by the respective connection of the first and second connecting elements 24, 48. Since, in the present embodiment, the brake rotor 43 and the motor rotor 33 are permanently connected to each other in a rotationally fixed manner, a rotationally fixed connection between the drive shaft 20 and the brake rotor 43 implies that the drive shaft 20 and the motor rotor 33 are also connected in a rotationally fixed manner. However, in the second axial position, the drive shaft 10 and the brake rotor 43 are not connected in a rotationally fixed manner, so that the drive shaft 20 can rotate freely relative to the motor assembly 30 and the brake assembly 40. Thus, by moving the drive shaft between the first and the second axial position, it is possible to selectively couple the electric motor 30 and the brake assembly 40 to or decouple them from the drive shaft 10.In this way, the present embodiment includes a coupling mechanism. In the illustrated embodiment, the electric motor system 1 also comprises a (motor) stator carrier 38 and a second bearing arrangement 52, which is mounted on the drive shaft 20 to rotatably support the stator carrier 38 on the drive shaft 20. In the illustrated example, the stator carrier 38 is arranged radially between the motor stator 31 and the drive shaft 20. The second bearing arrangement 52 is located in a central opening of the stator carrier 38 and thus radially between the stator carrier 38 and the drive shaft 20. The second bearing arrangement 52 comprises, for example, a ball bearing. Similar to the first bearing arrangement 51, the second bearing arrangement 52 is configured to allow axial movement (displacement) of the drive shaft 20, particularly relative to the motor rotor 33, the brake rotor 43, the brake stator 41, the motor stator 31, the motor stator carrier 38, and the housing 10. In the example shown, the stator support 38 can include cooling elements, such as cooling channels or pipes (not shown), to guide a cooling medium, such as oil, water, or air, through the stator support 38, and connections (not shown) that are fluidically connected to the cooling channels. For example, the cooling channels can be connected via the connections to a reservoir for the cooling medium, such as an oil bath and / or a heat exchanger. As mentioned above, the electric motor system 1 can be integrated into a vehicle's drive system (not shown), such as a (pure) electric vehicle or a hybrid vehicle, to drive one or more of the vehicle's wheels. The drive system may include other components configured to transmit torque from the electric motor to one or more of the vehicle's wheels, such as a transmission, drive shafts, and differentials. The vehicle may be, for example, a car, a motorcycle, or a bicycle. The vehicle may include one or more of the electric system 1. As described above, the drive system can include a cooling system, and the electric motor system 1 can be coupled to the cooling system of the drive system to cool the electric motor system 1, thereby cooling both the electric motor 30 and the brake arrangement 40 of the electric motor system 1. The vehicle's cooling system can, for example, be coupled with a vehicle heat exchanger to utilize heat generated by the brake assembly 40 and the electric motor 30 for heating the vehicle's driver / passenger compartment. The vehicle can also include a drive control system (not shown) configured to control the drive system. In particular, the drive control system is configured to control the electric motor 30 and the brake assembly 40 integrated into the drive system of the electric motor system 1. Specifically, the drive control system can be configured to integrate various control functions or strategies, such as mixing, ABS control, and stabilization control. As explained above in connection with the embodiment shown, the present disclosure contains various aspects and corresponding advantages. In particular, braking energy in the form of frictional heat is transferred from the brake rotor 43 to the motor rotor 33, where it can be stored, at least partially or temporarily. The braking energy can be removed from and dissipated from the electric motor system 1, for example, by means of water / air / oil cooling of the electric motor system or of a drive system of the vehicle. For example, it is possible to use an oil bath of the vehicle's drive system to cool the electric motor system 1. The same oil bath can be used to heat the driver / passenger compartment, for example, by means of a heat exchanger. Furthermore, environmental pollution from abrasion of the brake assembly 40 is avoided or at least reduced.Furthermore, it is possible to choose between different types and versions of brakes, such as internal block brakes, external block brakes, partial disc brakes, and full disc brakes. It is also possible to implement various brake concepts, such as a dry brake or a brake immersed in the drive system's oil bath. Hydraulic or electric brake actuation can be implemented on one side of the housing 10 or on two or more (opposite) sides of the housing 10. It is also possible to implement mixing, ABS control, and stability control to regulate the drive system. Moreover, due to the integration of the brake into the drive system, it is possible to eliminate brake components mounted on or near the wheels (such as brake discs, calipers, etc.).Further advantages of the electric motor system therefore include weight reduction and cost savings due to the reduction of a number of parts. Reference symbol list: 1 electric motor system 10 housing 11 first wall element 12 second wall element 13 third wall element 14 first opening 15 second opening 20 drive shaft 20' rod-shaped body 21 first end part 22 second end part 23 support part 24 first connecting elements 30 electric motor 31 motor stator 31' stator winding 33 motor rotor 33' motor magnet 36 central part of the motor rotor 37 peripheral part of the motor rotor 38 motor stator support 40 brake assembly 41 brake stator 42 brake pad 43 brake rotor 43' friction surface 44 brake actuator 45 electric motor of the brake actuator 46 central part of the brake rotor 47 peripheral part of the brake rotor 48 second connecting elements 49 drive element 51 first bearing assembly 52 second bearing assembly

Claims

Electric motor system (1) comprising: a housing (10); a drive shaft (20) rotatably mounted to rotate relative to the housing (10); an electric motor (30) installed in the housing (10) comprising a motor stator (31) attached to the housing (10) and a motor rotor (33) mounted on the drive shaft (20) to rotate relative to the motor stator (31);a brake arrangement (40) comprising a brake rotor (43) mounted on the drive shaft (20) within the housing (10) to rotate relative to the housing (10), the brake arrangement (40) further comprising a brake stator (41) with a brake pad (42) configured to be pressed against the brake rotor (43), the brake rotor (43) being adjacent to the motor rotor (33) to allow heat conduction from the brake rotor (43) to the motor rotor (33), the motor rotor (33) and the brake rotor (43) each having a contact surface extending around the drive shaft (20), the contact surface of the brake rotor (43) being adjacent to the contact surface of the motor rotor (33). Electric motor system (1) according to claim 1, wherein the brake rotor (43) and the motor rotor (33) are connected to each other in a rotationally fixed manner. Electric motor system (1) according to one of the preceding claims, wherein the motor rotor (33) and the brake rotor (43) each have a central part (36, 46), wherein each of the central parts (36, 46) has a central opening, wherein the drive shaft (20) passes through the respective central openings of the central parts (36, 46) of the brake rotor (43) and the motor rotor (33). Electric motor system (1) according to claim 3, wherein the central parts (36, 46) extend relative to the drive shaft (20) in a radially outward direction towards an inner wall of the housing (10). Electric motor system (1) according to one of claims 3 or 4, wherein the central parts (36, b46) of the brake rotor (43) and the motor rotor (33) are disc-shaped or ring-shaped. Electric motor system (1) according to one of claims 3 to 5, wherein the central parts (36, 46) of the brake rotor (43) and the motor rotor (33) have approximately the same diameter. Electric motor system (1) according to one of claims 3 to 6, wherein the motor rotor (33) has a peripheral part (37) extending from an outer circumference of the central part (36) of the motor rotor (33) in a direction away from the brake rotor (43), wherein at least one rotor magnet (33') of the motor rotor (33) is attached to the peripheral part (37) of the motor rotor (33). Electric motor system (1) according to one of the preceding claims, wherein the brake rotor (43) comprises a peripheral part (47) extending from an outer circumference of the central part (46) of the brake rotor (43) in a direction away from the motor rotor (33), wherein the brake pad (42) is configured to be pressed against the peripheral area (47). Electric motor system (1) according to one of the preceding claims, further comprising a first bearing arrangement (51) which is arranged radially between the drive shaft (20) and the motor rotor (33) and is configured to rotatably mount the motor rotor (33) on the drive shaft (20). Electric motor system (1) according to claim 9, wherein the first bearing arrangement (51) is furthermore arranged radially between the drive shaft (20) and the brake rotor (43) and is configured to support the brake rotor (43) on the drive shaft (20). Electric motor system (1) according to one of the preceding claims, wherein the drive shaft (20) has a rod-shaped body (20') and a support part (23) extending radially from the body (20'), wherein the support part (23) has at least one first connecting element (24) on a side facing the brake rotor (43), wherein the brake rotor (43) has at least one second connecting element (48) on a side facing the support part (23) of the drive shaft (20), wherein the drive shaft (20) is axially displaceable relative to the brake rotor (43) between a first axial position in which the support part (23) adjoins the brake rotor (43) and a second axial position in which the support part (23) is separated from the brake rotor (43), wherein the at least one first connecting element (24) is configured toto connect with the at least one second connecting element (48) to create a rotationally fixed connection between the brake rotor (43) and the drive shaft (20) when the drive shaft (20) is in the first axial position. Electric motor system (1) according to one of the preceding claims, further comprising a motor stator carrier (38) arranged radially between the motor stator (31) and the drive shaft (20), and a second bearing arrangement (52) arranged radially between the motor stator carrier (52) and the drive shaft (20). Electric motor system (1) according to one of the preceding claims, wherein the brake arrangement (40) further comprises a brake actuator (44) which is connected to the housing (10) and configured to press the brake pad (42) against the brake rotor (43). Vehicle comprising an electric motor system (1) according to any one of the preceding claims.

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