Electrical machinery

Abstract

The present invention relates to an electric machine (1) comprising a stator (2) and a rotor (3) rotatably mounted relative to the stator (2). The rotor (3) includes a rotor shaft (4) and a rotor body (5) rotatably fixed to the rotor shaft (4). The rotor shaft (4) has hydraulic fluid channels (6) extending axially and capable of being filled with a hydraulic fluid (16), and a first radial fluid channel (7) extending radially outward from the hydraulic fluid channel (6). At least one annular disk-shaped cover element (10) is rotatably fixed to the rotor body (5) on an axial end face (9) of the rotor body (5), the cover element (10) forming, together with the axial end face (9) of the rotor body (5), at least one first cooling passage (18) open on both sides, the first cooling passage (18) being hydraulically connectable to the first radial fluid passage (7) so that the working fluid (16) can be conveyed radially, in a centrifugally assisted manner, out of the working fluid passage (6) of the rotor shaft through the radial fluid passage (7) and the first cooling passage (18).

Description

[Technical field]

[0001] The present invention relates to an electric machine comprising a stator and a rotor rotatably mounted relative to the stator, the rotor including a rotor shaft and a rotor body connected in a rotatably fixed manner to the rotor shaft, the rotor shaft having hydraulic fluid passages extending in an axial direction and capable of being filled with a working fluid, a first radial fluid passage extending radially outward from the hydraulic fluid passages, at least one annular disk-shaped cover element connected to the rotor body in a rotatably fixed manner on an axial end face of the rotor body, the cover element forming, together with the axial end face of the rotor body, at least one first cooling passage open on both sides, the first cooling passage being hydraulically coupleable to the first radial fluid passage, so that the working fluid can be transported radially out of the working fluid passages of the rotor shaft and through the radial fluid passages and the first cooling passage in a centrifugally assisted manner. [Background technology]

[0002] Electric motors are increasingly being used to drive motor vehicles, creating an alternative to fossil fuel-hungry internal combustion engines. A great deal of effort has already been made to improve the suitability of electric drives for everyday use and to be able to offer users the driving comfort to which they are accustomed.

[0003] Permanently excited synchronous machines are used in many of these electromobility applications. Such permanently excited synchronous machines typically include an energized stator and a permanently excited rotor. The rotor typically consists of a shaft, balance plates, a laminated rotor core, and magnets. The magnets are typically fixed within the laminated rotor core.

[0004] The performance of a rotating electrical machine depends, among other things, on the heat generated during operation, since increased heat reduces the efficiency of the machine. It is also known that so-called hot spots can occur in rotating electric machines. Hot spots are areas in the rotor and / or stator that generate the most heat during operation of the electric machine.

[0005] Commonly used methods for cooling the rotors and stators of electric machines include cooling the rotor radially from the inside using a centrifugal coolant (the coolant flows along the end faces of the rotor) and cooling the stator radially from the outside using a coolant and the dissipation of the coolant, and therefore the heat absorbed by the coolant.

[0006] Due to the trend towards ever higher speeds of electric machines in the field of electromobility, rotor stacks generally require a lateral interference fit, which does not usually allow for a coolant supply to the stack. The high speeds of modern electric drives in the vehicle field also mean that suction effects associated with centrifugal forces occur in the radial coolant channels, which can result in uncontrolled distribution of the working fluid in the cooling system of the corresponding electric machine. The uncontrolled and undesired distribution of the working fluid resulting from such suction effects can result in insufficient cooling capacity in thermally critical areas of the electric machine. This leads to reduced efficiency of the electric machine and even thermal damage or failure of the electric machine. Summary of the Invention [Problem to be solved by the invention]

[0007] It is therefore an object of the present invention to provide an electric machine which reduces or completely eliminates these drawbacks and which is able to provide controlled and reliable cooling of the rotor even at high speeds. [Means for solving the problem]

[0008] This object is achieved by means of the measures set forth in the independent claims. Advantageous further embodiments are specified in the dependent claims. According to one aspect, an electric machine includes a stator and a rotor rotatably mounted relative to the stator, the rotor including a rotor shaft and a rotor body connected in a rotatably fixed manner to the rotor shaft, the rotor shaft having hydraulic fluid passages, the hydraulic fluid passages extending axially and capable of being filled with a hydraulic fluid, a first radial fluid passage extending radially outward from the hydraulic fluid passages, at least one annular disk-shaped cover element connected to the rotor body in a rotatably fixed manner on an axial end face of the rotor body, the cover element forming, together with the axial end face of the rotor body, at least one first cooling passage open on both sides, the first cooling passage capable of being hydraulically coupled to the first radial fluid passage. Thus, the working fluid can be conveyed in a centrifugally assisted manner out of the working fluid flow passages of the rotor shaft and radially through the radial fluid flow passages and the first cooling flow passages, the first radial fluid flow passages having a first flow cross section and a second flow cross section formed radially above the first flow cross section, the first flow cross section and the second flow cross section having a ratio of 1:1.5 to 1:25, 5% to 75%, preferably 15 to 25%, of the second flow cross section of the first radial fluid flow passage being partially covered in the axial direction by the rotor body, the second flow cross section opening into a first storage chamber arranged radially between the rotor shaft and the first cooling flow passages, the volume of the first radial fluid flow passage having a ratio of 0.5:1 to 3:1 to the volume of the first storage chamber.

[0009] This configuration of the hydraulic cooling paths on the rotor of the electric machine according to the invention makes it possible to reliably prevent the occurrence of suction effects at high speeds.

[0010] The axial overlap of the second flow cross section of the first radial fluid passage by the rotor body may improve wetting of the rotor body, especially at high speeds.

[0011] In the context of the present invention, the terms "axial" and "radial" always refer to the axis of rotation of the rotor.

[0012] First, each element of the claimed subject matter of the present invention will be described in the order in which it appears in the claims, and then particularly preferred embodiments of the present subject matter will be described below.

[0013] An electric machine is used to convert electrical energy into mechanical energy and / or vice versa and generally comprises a fixed part called the stator or armature and a part called the rotor, arranged movably relative to the fixed part. This electric machine is in particular intended for use in the drive train of a hybrid or fully electric vehicle. In particular, the electric machine is dimensioned such that vehicle speeds of more than 50 km / h, preferably more than 80 km / h, in particular more than 100 km / h can be achieved. The electric motor particularly preferably has a power output of more than 30 kW, preferably more than 50 kW, in particular more than 70 kW. Furthermore, it is preferred that the electric machine provides a speed of more than 5,000 rpm, particularly preferably more than 10,000 rpm, very particularly preferably more than 12,500 rpm.

[0014] The electric machine according to the invention is configured in particular as a radial flux machine, in particular for use in a drivetrain of a motor vehicle, which in the context of the present application is understood to mean all the components in the motor vehicle which generate the power for driving the motor vehicle and transfer said power via the wheels to the road.

[0015] The stator of the electric machine is preferably cylindrically constructed and preferably consists of electrical laminations which are electrically insulated from one another, constructed in layers and packaged to form a laminated core.

[0016] The rotor is the rotating (spinning) part of the electric machine. It comprises a rotor shaft and one or more rotor bodies arranged in a rotationally fixed manner on the rotor shaft. The rotor shaft may be hollow, which reduces weight while allowing lubricant or coolant to be supplied to the rotor bodies.

[0017] A rotor body in the context of the present invention is understood to mean a rotor without a rotor shaft, which is therefore composed in particular of the laminated rotor core, the magnetic elements introduced into the pockets of the laminated rotor core or fixed circumferentially thereto, and any axial cover parts present to close the pockets.

[0018] The rotor body may comprise one or more laminated rotor cores, also called stacks. A laminated rotor core is understood to mean a number of laminated individual layers or rotor plies, typically made from electrical sheet metal, stacked one on top of the other and packaged to form a stack, which is called a laminated rotor core. The individual layers may be held together, as a laminated core, by gluing, welding or screwing.

[0019] The electric machine may further comprise a cooling system, which is used to dissipate heat generated by electrical losses in the electric machine. Such a cooling system may have cooling channels in the rotor (rotor cooling channels) and / or in the stator (stator cooling channels), through which a corresponding cooling medium or working fluid is guided in order to dissipate heat. For this purpose, the cooling system may in particular have one or more pumps which move the cooling medium through the cooling system, preferably in a closed circuit.

[0020] In electric machines, the working fluid has the function of dissipating heat as efficiently as possible from heated areas of the electric machine, avoiding undesired overheating of these areas. In addition to this main purpose, the working fluid can also provide lubrication and corrosion protection for the metal surfaces of the moving parts of the electric machine and for the cooling system. Furthermore, it can dissipate impurities (e.g. due to wear), water and air, among others.

[0021] The working fluid is preferably a liquid. It may in particular be an oil. However, in principle it is also conceivable to use an aqueous working fluid, for example an emulsion.

[0022] Furthermore, the electric machine can preferably be provided for use in a hybrid module for a motor vehicle, in which the structural and functional elements of the hybridized drivetrain can be preconfigured in a spatial and / or structural combination, such that the hybrid module can be integrated in a particularly simple manner into the drivetrain of the motor vehicle. In particular, the electric machine and a clutch system, in particular a clutch system with a separating clutch for engaging and / or disengaging the electric machine from the drivetrain, can be present in the hybrid module.

[0023] In particular, the electric machine can also be preferably provided for use in an electric axle drivetrain in a drivetrain of a motor vehicle, the electric axle drivetrain of the motor vehicle comprising an electric machine and a transmission, the electric machine and the transmission forming a structural unit, also called an E-axle.

[0024] According to an advantageous embodiment of the invention, the rotor shaft has hydraulic fluid channels extending in the axial direction and capable of being filled with a hydraulic fluid, a first radial fluid channel and an axially spaced second radial fluid channel extending radially outward from the hydraulic fluid channel, on an axial end face of the rotor body at least one annular disk-shaped cover element is connected to the rotor body in a rotatably fixed manner, and the cover element forms, together with one of the axial end faces of the rotor body, at least one cooling channel open on both sides, which cooling channel can be hydraulically coupled to one of the radial fluid channels, so that the rotor has at least one corresponding first cooling channel and at least one second cooling channel, Thus, the working fluid can be transported radially from the working fluid flow passage of the rotor shaft and through the radial fluid flow passages and the cooling flow passages by centrifugal force, the second radial fluid flow passage having a third flow cross section and a fourth flow cross section formed radially above the third flow cross section, the third flow cross section and the fourth flow cross section having a ratio of 1:1.5 to 1:25, 5% to 75%, preferably 15 to 25%, of the fourth flow cross section of the second radial fluid flow passage is partially covered in the axial direction by the rotor body, and the fourth flow cross section opens into a second storage chamber arranged radially between the rotor shaft and the second cooling flow passage, and the volume of the first radial fluid flow passage can also have a ratio of 0.5:1 to 3:1 with respect to the volume of the first storage chamber.

[0025] The advantage of this configuration is that the configuration of the hydraulic system ensures that suction effects are avoided, allowing the working fluid to be evenly distributed between the two hydraulic paths for cooling the rotor body.

[0026] The number of cooling channels between the cover element and the rotor body particularly preferably corresponds to the number of pole pairs, very particularly preferably to twice the number of pole pairs, in order to achieve the most symmetrical possible cooling capacity over the circumference of the stator body. The cooling channels are preferably of identical design and extend along radial straight lines. Furthermore, the cooling channels are preferably arranged equidistantly over the circumference of the rotor body.

[0027] The cover elements are preferably made from high strength aluminum to provide sufficient strength.

[0028] According to a further preferred development of the invention, the first cooling channel can have a flow cross-section that corresponds to 0.5-1.5 of the first flow cross-section of the first radial fluid channel. Furthermore, according to an equally advantageous embodiment of the invention, the second cooling channel can have a flow cross-section that corresponds to 0.5-1.5 of the third flow cross-section of the second radial fluid channel. These measures also help to prevent the occurrence of undesirable suction effects.

[0029] The cooling channel or channels can be formed in particular in the end face of the annular disk-shaped cover element facing the rotor body and are particularly preferably introduced into the cover element by embossing. The end face of the annular disk-shaped cover element facing away from the rotor body can in particular be of planar design, so that for example development of sensor functions requiring a planar sensor target design can be made. For example, the cover element can be made of aluminum and has pocket-like recesses arranged equidistantly in the circumferential direction, which are detected by an incremental sensor as the rotor rotates and processed as a rotor position signal.

[0030] According to a further particularly preferred embodiment of the invention, at least one of the cover elements can have an outlet channel extending in the axial direction, in this way the effect can be achieved in particular that the axially exiting working fluid can be directed towards the stator winding overhangs which are arranged radially above the outlet channel and which can usually be subject to high thermal loads, improving the cooling of the entire electric machine. It is particularly preferred that the outlet channel is located essentially in the center of the magnetic pocket present in the rotor body.

[0031] Furthermore, the invention can be further developed such that the outlet flow passage has a flow cross-section corresponding to 50-300% of the first flow cross-section of the first or second radial fluid flow passage, thereby further suppressing undesirable suction effects.

[0032] In a variant of an equally preferred embodiment of the invention, at least one of the cover elements can have a chamfer on its radially inner side, so that there is a funnel-shaped transition between one of the cooling channels and the corresponding reservoir. This also supports a uniform supply of the working fluid to the hydraulic cooling paths of the rotor, since it has been shown that the undesirable suction effect is further reduced by the funnel-shaped transition. The chamfer also guides the working fluid towards the rotor body, which has a beneficial effect on cooling. In one possible embodiment of the invention, the chamfer can extend radially completely through the reservoir, thus forming a ring-shaped reservoir wall.

[0033] It may also be advantageous to further develop the invention so that the rotor operates at speeds of up to 12,000-18,000 rpm, with the hydraulic system operating particularly efficiently and safely in these speed ranges to reduce or avoid undesirable suction effects.

[0034] According to a further preferred embodiment of the subject matter of the present invention, the working fluid flow path of the rotor shaft may have a third radial fluid flow path which extends radially outward and is arranged axially outside the rotor body within the rotor shaft, thereby enabling cooling of further components in the electric machine, in particular outside the rotor body.

[0035] Finally, the invention can also be advantageously implemented in such a way that at least one of the storage chambers has a radially outer contour that is convex in cross section and curves radially outward, which has proven to be an effective measure for reducing or avoiding undesirable suction effects.

[0036] The invention is explained in more detail below with reference to the drawings, without limiting the general concept of the invention. [Brief description of the drawings]

[0037] [Figure 1] 1 shows an electric machine in axial section; [Diagram 2] 1 shows a rotor of an electric machine in axial section; [Diagram 3] 1 shows a detailed view of an axial section of the area surrounding the reservoir of the rotor. [Figure 4] A cross-sectional view of the rotor is shown. [Diagram 5] 1 shows a schematic block diagram of a vehicle with a hybrid and fully electric drivetrain; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] 1 shows an electric machine 1 comprising a stator 2 and a rotor 3 rotatably mounted relative to the stator 2. The rotor 3 has a rotor shaft 4 and a rotor body 5 connected to the rotor shaft 4 in a rotatably fixed manner.

[0039] As is clear from Figure 2, the rotor shaft 4 has hydraulic fluid channels 6 which extend axially and can be filled with a hydraulic fluid 16, from which first radial fluid channels 7 extend radially outward. At both axial end faces 9 of the rotor body 5, annular disk-shaped cover elements 10 are connected in a rotatably fixed manner to the rotor body 5. The hydraulic fluid 16 can be conveyed by means of a hydraulic pump (not shown) through a hydraulic system which will be described below.

[0040] Together with the axial end face 9 of the rotor body 5, the cover element 10 forms at least one first cooling passage 18 open on both sides, which can be hydraulically coupled to the first radial fluid passage 7 so that the working fluid 16 can be transported radially out of the working fluid passage 6 of the rotor shaft and through the radial fluid passage 7 and the first cooling passage 18 in a centrifugally assisted manner.

[0041] As shown in the detailed view of Fig. 3, the first radial fluid passage 7 has a first flow cross section 12 and a second flow cross section 13 formed radially above the first flow cross section 12. The first flow cross section 12 and the second flow cross section 13 have a ratio of 1:1.5 to 1:25, and 15 to 25% of the second flow cross section 13 of the first radial fluid passage 7 is partially covered in the axial direction by the rotor body 5. The second flow cross section 13 opens into a first storage chamber 17 arranged radially between the rotor shaft 4 and the first cooling passage 18, and the volume of the first radial fluid passage 7 has a ratio of 0.5:1 to 3:1 to the volume of the first storage chamber 17.

[0042] 2, starting from the hydraulic fluid flow passage 6, a first radial fluid flow passage 7 and a second radial fluid flow passage 8 axially spaced apart from the first radial fluid flow passage 7 extend radially outward. Here too, the cover element 10 together with a corresponding axial end face 9 of the rotor body 5 forms at least one cooling passage open on both sides, which can be hydraulically coupled to the radial fluid flow passage 8, so that the rotor 3 has at least one corresponding first cooling passage 18 and at least one second cooling passage 19.

[0043] Thus, the working fluid 16 can be transported radially out of the working fluid passage 6 of the rotor shaft 4 by centrifugal force through the radial fluid passages 7, 8 and the cooling passages 18, 19. Similar to the first radial fluid passage, the second radial fluid passage 8 also has a third flow cross section 14 and a fourth flow cross section 15 formed radially above the third flow cross section 14, the third flow cross section 14 and the fourth flow cross section 15 having a ratio of 1:1.5 to 1:25, and 15 to 25% of the fourth flow cross section 15 of the second radial fluid passage 8 is partially covered in the axial direction by the rotor body 5. The fourth flow cross section 12 opens into a second storage chamber 24 arranged radially between the rotor shaft 4 and the second cooling passage 19, the volume of the second radial fluid passage 8 having a ratio of 0.5:1 to 3:1 to the volume of the second storage chamber 24.

[0044] The cover elements 10 each have an axially extending outlet channel 20 with a flow cross-section 21 which corresponds to 50-300% of the first flow cross-section 12, 14 of the first or second radial fluid channel 7, 8. This allows the working fluid 16 to be discharged out of the rotor 2 onto the end windings of the stator 2 and to cool the latter accordingly, as can be clearly seen from Figure 1. The cooling channels 18, 19 can in particular be embossed in the cover element 10 so that machining can be omitted.

[0045] As is evident from FIG. 2, the two hydraulic paths starting from the first and third flow cross sections 12, 14 to the respective outlet passages 20 are essentially of identical design.

[0046] It can also be easily seen from FIG. 3 that the first cooling passage 18 has a flow cross-section that is 0.5 to 1.5 of the first flow cross-section 12 of the first radial fluid passage 7, and the second cooling passage 19 has a flow cross-section that corresponds to 0.5 to 1.5 of the third flow cross-section 14 of the second radial fluid passage 8.

[0047] Each cover element 10 has a chamfer 23 on its radially inner side 22 such that there is a funnel-shaped transition between one of the cooling channels 18,19 and the corresponding storage chamber 17,24.

[0048] The hydraulic fluid flow passages 6 of the rotor shaft 4 also have a third radial fluid flow passage 25 extending radially outward and arranged axially within the rotor shaft 4 outside the rotor body 5. The third radial fluid flow passage 25 is provided in particular for cooling other components of the electric machine 1.

[0049] Figure 4 is a cross-sectional view of the rotor 3 seen from figure 2. Four cooling channels 18, 19 can be seen which are circumferentially offset from one another by 90° and extend radially outward from the rotor shaft 4, each opening into an outlet channel 20. This cross-sectional view clearly shows that each of the storage chambers 17, 24 has a radially outer contour 26 which is convex in cross-section and curved radially outward.

[0050] The electric machine 1 is particularly intended for use in a hybrid or fully electric drivetrain 28 of a motor vehicle 27, as shown by way of example in Fig. 5. In the upper illustration of Fig. 5 a hybrid module 30 with the electric machine 1 is integrated into the drivetrain 28, and in the lower illustration an electric axle drivetrain 29 with the electric machine 1 is integrated into the drivetrain 28 of the corresponding motor vehicle 27.

[0051] The present invention is not limited to the illustrated embodiments. Therefore, the above description should not be considered as limiting, but rather as exemplary. The following claims should be understood as meaning that the specified features are present in at least one embodiment of the present invention. This does not exclude the presence of additional features. Where the claims and the above description define a "first" and a "second" feature, this designation serves to distinguish two features of the same type, without defining a priority order. [Explanation of symbols]

[0052] 1 Electrical machinery 2 Stator 3 Rotor 4 rotor shaft 5 Rotor body 6 Hydraulic fluid flow path 7 First radial fluid flow passage 8 Second radial fluid flow passage 9 End face 10 Cover Elements 12 First flow section 13 Second flow section 14 Third flow section 15 Fourth flow section 16 Working Fluid 17 First Storage Room 18 First cooling channel 19 Second cooling channel 20 Outlet Channel 21 Flow Section 22 Side 23 Chamfering 24 Second Storage Room 25 third radial fluid flow passage 26 Radial Contour 27 Automobiles 28 Drivetrain 29 Electric Axle Drivetrain 30 Hybrid Module

Claims

1. An electric machine (1) comprising a stator (2) and a rotor (3) rotatably mounted relative to the stator (2), the rotor (3) comprising a rotor shaft (4) and a rotor body (5) connected in a rotatably fixed manner to the rotor shaft (4), the rotor shaft (4) having hydraulic fluid channels (6) extending in an axial direction and capable of being filled with a hydraulic fluid (16), a first radial fluid channel (7) extending radially outward from the hydraulic fluid channel (6), at least one annular disk-shaped cover element (10) being arranged in the axial direction of the rotor body (5), 1. An electric machine (1), comprising: a cover element (10) connected to said rotor body (5) in a rotatably fixed manner on an end face (9) and forming, together with said axial end face (9) of said rotor body (5), at least one first cooling channel (18) open on both sides, said first cooling channel (18) hydraulically connectable to said first radial fluid channel (7) so that said working fluid (16) can be conveyed in a centrifugally assisted manner out of said working fluid channel (6) of the rotor shaft and in said radial direction through said radial fluid channel (7) and said first cooling channel (18), the first radial fluid flow passage (7) has a first flow cross-section (12) and a second flow cross-section (13) formed in the radial direction above the first flow cross-section (12), the first flow cross-section (12) and the second flow cross-section (13) having a ratio of 1:1.5 to 1:25, 5% to 75% of the second flow cross-section (13) of the first radial fluid flow passage (7) is partially covered in the axial direction by the rotor body (5), the second flow cross-section (13) opens into a first storage chamber (17) arranged in the radial direction between the rotor shaft (4) and the first cooling channel (18), and a volume of the first radial fluid flow passage (7) has a ratio of 0.5:1 to 3:1 with respect to a volume of the first storage chamber (17).

2. The rotor shaft (4) has a hydraulic fluid flow passage (6) extending in the axial direction and capable of being filled with a hydraulic fluid (16), a first radial fluid flow passage (7) and a second radial fluid flow passage (8) spaced apart in the axial direction from the first radial fluid flow passage (7) extending radially outward from the hydraulic fluid flow passage (6), and at least one annular disk-shaped cover element (10) is fixed in a rotatable manner on the axial end face (9) of the rotor body (5). The cover element (10) is connected to the rotor body (5) and is connected to one of the axial end faces (9) of the rotor body (5) to form at least one cooling channel (19) open on both sides, the cooling channel (19) being hydraulically connectable to one of the radial fluid channels (7, 8), so that the rotor (3) has at least one corresponding first cooling channel (18) and at least one second cooling channel (19), so that the working flow a second radial fluid flow passage (8) having a third flow cross section (14) and a fourth flow cross section (15) formed in the radial direction above the third flow cross section (14), the third flow cross section (14) and the fourth flow cross section (15) having a ratio of 1:1.5 to 1:25, the second flow cross section (8) being capable of conveying a body (16) out of the working fluid flow passage (6) of the rotor shaft and through the radial fluid flow passages (7, 8) and the cooling flow passages (18, 19) by centrifugal force, the second radial fluid flow passage (8) having a third flow cross section (14) and a fourth flow cross section (15) formed in the radial direction above the third flow cross section (14), the third flow cross section (14) and the fourth flow cross section (15) having a ratio of 1:1.5 to 1:25, 2. An electric machine according to claim 1, characterized in that 5% to 75% of the fourth flow cross section (15) of the radial fluid flow passage (8) is partially covered in the axial direction by the rotor body (5) and the fourth flow cross section (12) opens into a second storage chamber (24) arranged in the radial direction between the rotor shaft (4) and the second cooling channel (19), and the volume of the second radial fluid flow passage (8) has a ratio to the volume of the second storage chamber (24) of 0.5:1 to 3:

1.

3. 3. The electric machine (1) according to claim 2, characterized in that the second cooling channel (19) has a flow cross-section that corresponds to 0.5 to 1.5 of the third flow cross-section (14) of the second radial fluid channel (8).

4. 4. An electric machine (1) according to claim 1, characterized in that the first cooling channel (18) has a flow cross-section which corresponds to 0.5 to 1.5 of the first flow cross-section (12) of the first radial fluid channel (7).

5. 5. Electric machine (1) according to any one of the preceding claims, characterized in that at least one of the cover elements (10) has an outlet channel (20) extending in the axial direction.

6. At least one of the cover elements (10) has an outlet flow passage (20) extending in the axial direction, 3. The electric machine (1) according to claim 2, characterized in that the outlet flow passage (20) has a flow cross-section (21) which corresponds to 50 to 300% of the first flow cross-section (12) of the first radial fluid flow passage (7) or the third flow cross-section (14) of the second radial fluid flow passage (8).

7. 7. An electric machine (1) according to claim 1, characterized in that at least one of the cover elements (10) has a chamfer (23) on its radially inner side (22) such that there is a funnel-shaped transition between one of the cooling channels (18, 19) and the corresponding storage chamber (17, 24).

8. An electric machine (1) according to any one of the preceding claims, characterized in that the rotor (3) operates at a maximum speed of 12,000 to 18,000 rpm.

9. 9. An electric machine (1) according to claim 1, characterized in that the hydraulic fluid flow paths (6) of the rotor shaft (4) comprise a third radial fluid flow path (25), the third radial fluid flow path (25) extending radially outward and arranged in the rotor shaft (4) in the axial direction outside the rotor body (5).

10. 10. An electric machine (1) according to any one of claims 1 to 9, wherein at least one of the storage chambers (17, 24) has a radially outer contour (26), characterized in that the radially outer contour (26) is convex in cross section and curves radially outward.

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