An electric rotating machine

Abstract

An electric rotating machine (400) comprising a stator (404) and a rotor (100) rotatable in relation to the stator (404). The rotor (100) comprises a rotor shaft (102) configured to rotate together with the rotor (100) about an axis of rotation (104). The rotor shaft (102) comprises a shell (126) and an inner section (128). The shell (126) houses the inner section (128). The rotor shaft (102) forms an internal compartment (122) for guiding a cooling fluid. The internal compartment (122) is formed between the inner section (128) and the shell (126). The electric rotating machine (400) comprises a discharge arrangement (600) for discharging an electrical charge and / or a voltage from the rotor shaft (102). The discharge arrangement (600) comprises a first contact device (602) for direct or indirect electrical contact with a second contact device (604). The first contact device (602) is rotatable in relation to the second contact device (604). The inner section (128) is electrically connected to the rotor shaft (102). The first contact device (602) comprises a portion of the inner section (128).

Description

[0001] AN ELECTRIC ROTATING MACHINE

[0002] Technical field

[0003] Aspects of the present invention relate to an electric rotating machine.

[0004] Background

[0005] In general, an electric rotating machine comprises a stator and a rotor rotatable about an axis of rotation in relation to the stator. In general, at least one of the rotor and stator may be provided with one or more windings, one or more permanent magnets, or one or more other elements interacting with the stator or rotor. In general, electric rotating machines are equipped with a fluid system for cooling one or more of the rotor and stator, since during operation of the electric rotating machine one or more of the rotor and stator may be heated to such a degree that cooling is advisable. The fluid system may guide a cooling fluid, such as oil, or any other fluid, in one or more channels or compartments to cool one or more of the rotor and stator. Further, some electric rotating machines are equipped with arrangements for grounding the rotor shaft so as to discharge electrical charge from the rotor shaft.

[0006] Summary

[0007] The inventors of the present invention have found drawbacks in conventional electric rotating machines. For example, some conventional electric rotating machines do not provide a sufficiently efficient or sufficiently adequate grounding of the rotor shaft. For some conventional electric rotating machines, there is limited space for installations and equipment regarding the grounding of the rotor shaft, which may be the case in vehicles.

[0008] An object of the invention is to provide a solution which mitigates or solves the drawbacks and problems of conventional solutions.

[0009] The above and further objects are solved by the subject matter of the independent claim. Further advantageous embodiments of the invention can be found in the dependent claims. According to a first aspect of the invention, the above mentioned and other objects are achieved with an electric rotating machine comprising a stator and a rotor rotatable in relation to the stator, wherein the rotor comprises a rotor shaft configured to rotate together with the rotor about an axis of rotation in relation to the stator, wherein the rotor shaft comprises a shell and an inner section, wherein the shell houses the inner section, wherein the shell and the inner section are configured to rotate together with the rotor shaft, wherein the rotor shaft forms an internal compartment for guiding a cooling fluid, wherein the internal compartment is formed between the inner section and the shell, wherein the electric rotating machine comprises a discharge arrangement for discharging an electrical charge and / or a voltage from the rotor shaft, wherein the discharge arrangement comprises a first contact device for direct or indirect electrical contact with a second contact device, wherein the first contact device is rotatable in relation to the second contact device, wherein the inner section is electrically connected to the rotor shaft, and wherein the first contact device comprises a portion of the inner section.

[0010] An advantage of the electric rotating machine according to the first aspect is an improved discharging of electrical charge and / or voltage from the rotor shaft. An advantage of the electric rotating machine according to the first aspect is an improved grounding of the rotor shaft by way of the innovative discharge arrangement. By way of the innovative discharge arrangement, an advantage of the electric rotating machine according to the first aspect is an improved grounding of any bearing currents caused by induced voltage in the rotor shaft, which are disclosed in more detail in the detailed description hereinbelow. An advantage of the electric rotating machine according to the first aspect is a flexible and / or modular discharge arrangement for the grounding of the rotor shaft and / or of any bearing currents, which can be adapted to different designs of the electric rotating machine and to different designs of surrounding structures and / or apparatuses. An advantage of the electric rotating machine according to the first aspect is a less bulky discharge arrangement for the grounding of the rotor shaft and / or of any bearing currents. An advantage of the electric rotating machine according to the first aspect is an increased reliability and / or durability of the discharge arrangement in relation to conventional solutions. An advantage of the electric rotating machine according to the first aspect is a robust discharge arrangement for the grounding of the rotor shaft and / or of any bearing currents, for example robust against vibrations and geometrical misalignments, for example during assembly and service, but also during operation. An advantage of the electric rotating machine according to the first aspect is a facilitated service and maintenance of the discharge arrangement for the grounding of the rotor shaft and / or of any bearing currents.

[0011] For some embodiments, it may be defined that the first contact device is, or consists of, a portion of the inner section.

[0012] According to an advantageous embodiment of the electric rotating machine according to the first aspect, the first contact device is rotatable about the axis of rotation in relation to the second contact device. An advantage of this embodiment is a further improved discharging of electrical charge and / or voltage from the rotor shaft. An advantage of this embodiment is a further improved grounding of the rotor shaft and / or of any bearing currents.

[0013] According to a further advantageous embodiment of the electric rotating machine according to the first aspect, the inner section has an outer surface, wherein the first contact device comprises a contact surface for the electrical contact with the second contact device, wherein the contact surface of the first contact device comprises a portion of the outer surface of the inner section.

[0014] According to another advantageous embodiment of the electric rotating machine according to the first aspect, the axis of rotation extends through the contact surface of the first contact device. An advantage of this embodiment is a further improved discharging of electrical charge and / or voltage from the rotor shaft. An advantage of this embodiment is a further improved grounding of the rotor shaft and / or of any bearing currents.

[0015] According to yet another advantageous embodiment of the electric rotating machine according to the first aspect, the first contact device comprises a recess formed by the inner section, wherein the first contact device is configured to receive and accommodate at least a portion of the second contact device in the recess of the first contact device. An advantage of this embodiment is a further improved discharging of electrical charge and / or voltage from the rotor shaft. An advantage of this embodiment is a further improved grounding of the rotor shaft and / or of any bearing currents. An advantage of this embodiment is a further improved reliability, durability and / or robustness of the discharge arrangement in relation to conventional solutions. An advantage of this embodiment is an even less bulky discharge arrangement for the grounding of the rotor shaft and / or of any bearing currents.

[0016] According to still another advantageous embodiment of the electric rotating machine according to the first aspect, the recess opens in a direction in parallel to the axis of rotation. An advantage of this embodiment is a further improved reliability, durability and / or robustness of the discharge arrangement in relation to conventional solutions.

[0017] According to an advantageous embodiment of the electric rotating machine according to the first aspect, the inner section comprises a first end portion and a second end portion, wherein the inner section has a longitudinal extension extending from the first end portion to the second end portion, wherein the longitudinal extension of the inner section extends in a direction in parallel to the axis of rotation, and wherein the first contact device comprises a portion of the first end portion.

[0018] An advantage of this embodiment is a further improved discharging of electrical charge and / or voltage from the rotor shaft. An advantage of this embodiment is a further improved grounding of the rotor shaft and / or of any bearing currents. An advantage of this embodiment is a further improved reliability, durability and / or robustness of the discharge arrangement in relation to conventional solutions.

[0019] According to a further advantageous embodiment of the electric rotating machine according to the first aspect, the discharge arrangement comprises one or more bearings attached to the first contact device, wherein the one or more bearings of the discharge arrangement is / are configured to at least partially support the second contact device. An advantage of this embodiment is a further improved discharging of electrical charge and / or voltage from the rotor shaft. An advantage of this embodiment is a further improved grounding of the rotor shaft and / or of any bearing currents. An advantage of this embodiment is a further improved reliability, durability and / or robustness of the discharge arrangement in relation to conventional solutions.

[0020] According to another advantageous embodiment of the electric rotating machine according to the first aspect, the discharge arrangement comprises the second contact device, wherein the second contact device comprises an electrically conductive and elongated grounding device having a longitudinal extension extending in a direction in parallel to the axis of rotation. An advantage of this embodiment is a further improved discharging of electrical charge and / or voltage from the rotor shaft. An advantage of this embodiment is a further improved grounding of the rotor shaft and / or of any bearing currents. An advantage of this embodiment is a further improved reliability, durability and / or robustness of the discharge arrangement in relation to conventional solutions.

[0021] According to still another advantageous embodiment of the electric rotating machine according to the first aspect, the discharge arrangement comprises the second contact device, wherein the second contact device comprises an electrically conductive contact member for the electrical contact with the first contact device, wherein at least the contact member is movable in a direction in parallel to the axis of rotation in relation to the first contact device, and wherein the discharge arrangement comprises a biasing arrangement for urging the contact member in a direction toward the first contact device. An advantage of this embodiment is a further improved discharging of electrical charge and / or voltage from the rotor shaft. An advantage of this embodiment is a further improved grounding of the rotor shaft and / or of any bearing currents. An advantage of this embodiment is a further improved reliability, durability and / or robustness of the discharge arrangement in relation to conventional solutions.

[0022] According to yet another advantageous embodiment of the electric rotating machine according to the first aspect, the electric rotating machine comprises a casing housing at least the rotor and the discharge arrangement, wherein the discharge arrangement is configured to discharge an electrical charge and / or a voltage from the rotor shaft to a first section of the casing via the first and second contact devices. An advantage of this embodiment is a further improved discharging of electrical charge and / or voltage from the rotor shaft. An advantage of this embodiment is a further improved grounding of the rotor shaft and / or of any bearing currents.

[0023] According to an advantageous embodiment of the electric rotating machine according to the first aspect, the first contact device is electrically connectable to the first section of the casing via the second contact device.

[0024] According to a further advantageous embodiment of the electric rotating machine according to the first aspect, the electric rotating machine comprises one or more bearings for supporting the rotor shaft.

[0025] According to another advantageous embodiment of the electric rotating machine according to the first aspect, the rotor comprises an annular outer section for electromechanical interaction with the stator, wherein the annular outer section is attached to the rotor shaft and configured to rotate together with the rotor shaft, and wherein the inner section is electrically connected to the annular outer section.

[0026] According to a second aspect of the invention, the above mentioned and other objects are achieved with a vehicle comprising one or more electric rotating machines according to any one of the embodiments disclosed above or below. Advantages of the vehicle according to the second aspect and its embodiments correspond to advantages of the electric rotating machine according to the first aspect and its embodiments mentioned above or below.

[0027] The vehicle may be a wheeled vehicle, i.e. a vehicle having wheels. The vehicle may for example be a bus, a tractor vehicle, a heavy vehicle, a truck, or a car. The tractor vehicle, and / or the truck, may, or may be configured to, haul, or pull, a trailer. However, other types of vehicles are possible. The vehicle may be referred to as a motor vehicle. The vehicle may be an electric vehicle, EV, for example a hybrid vehicle or a hybrid electric vehicle, HEV, or a battery electric vehicle, BEV. Thus, a hybrid electric vehicle, HEV, and a battery electric vehicle, BEV, are versions, or examples, of an electric vehicle, EV. The electric vehicle, EV, may comprise one or more electric motors or electrical machines. The vehicle may comprise a combustion engine. For some embodiments, the vehicle may include only a combustion engine for the propulsion of the vehicle.

[0028] The vehicle may comprise a powertrain. The powertrain may be configured in accordance with any one of the embodiments disclosed below. The powertrain of the vehicle may comprise one or more of the group of: a combustion engine; an electric battery cell unit; an electric battery arrangement; and an electric battery pack.

[0029] The above-mentioned features and embodiments of the electric rotating machine and the vehicle, respectively, may be combined in various possible ways providing further advantageous embodiments.

[0030] Further advantageous embodiments of the electric rotating machine and the vehicle according to the present invention and further advantages with the embodiments of the present invention emerge from the detailed description of embodiments. Brief Description of the Drawings

[0031] Embodiments of the invention will now be illustrated, for exemplary purposes, in more detail by way of embodiments and with reference to the enclosed drawings, where similar references are used for similar parts, in which:

[0032] Figure 1 is a schematic diagram of a conventional electric rotating machine;

[0033] Figure 2 is a schematic sectional side view of an embodiment of the electric rotating machine according to the first aspect of the invention;

[0034] Figure 3 is an enlargement of a region of the electric rotating machine of figure 2;

[0035] Figure 4 is a schematic party sectional side view of the electric rotating machine of figure 2 connected to parts of a propulsion system of a vehicle;

[0036] Figure 5 is a schematic perspective view of an embodiment of the rotor of an embodiment of the electric rotating machine according to the first aspect of the invention provided with an annular outer section for electromechanical interaction with the stator;

[0037] Figure 6 is a schematic perspective view of the annular outer section of figure 5;

[0038] Figure 7 is a schematic diagram illustrating an embodiment of a fluid cooling system for cooling one or more of the rotor and stator of an embodiment of the electric rotating machine according to the first aspect of the invention; and Figure 8 is a schematic diagram of an embodiment of the vehicle according to the second aspect of the invention.

[0039] Detailed Description

[0040] Figure 1 schematically illustrates a conventional electric rotating machine 700 in order to schematically illustrate bearing currents already mentioned above. In conventional electric rotating machines having a rotor 712, which includes a rotor shaft 705, and stator 714 housed in a casing 716, and where the rotor shaft 705 of the electric rotating machine 700 is supported by two bearings 702, 704, bearing currents occur when there is an induced voltage on the rotor shaft 705 that is high enough to overcome the breakdown voltage on the bearing lubricant. In general, said breakdown voltage is greater than 50 V. Said induced voltage on the rotor shaft 705 will either cause an electric current to flow directly from the rotor shaft, through one of the bearings, then through the casing of the electric rotating machine 700, and then into ground or cause electric currents to circulate from one side of the rotor shaft 705, through one of the bearings, through the casing of the electric rotating machine, through the other opposite bearing, and then back to the rotor shaft. These induced electric currents through the bearings are called bearing currents. The bearing currents wear down the inner and outer races of the bearing and eventually cause the races to fail. During operation of the electric rotating machine, the bearing currents result in defects in the bearing race, for example in the form of “fluting”, “frosting”, or “pitting”, i.e., the formation of different kinds of small cavities in the bearing races, and as a consequence, the bearing rotation will no longer be smooth. Other negative effects of bearing currents are degrading or aging of the bearing lubricant because of sparks produced by the unsmooth bearing rotation, and increased noise from the bearing operation. Said circulation of the electric currents may be avoided by replacing 702 one of the two bearings 702, 704 with a so called hybrid bearing 702, as illustrated in figure 1 . A hybrid bearing 702 may, for example, have balls made of a ceramic material, and thus in general block any bearing current through the hybrid bearing 702, thereby making the side with the hybrid bearing 702 to an insulated side 706 (non-driving end / power take-off, NDE / PTO) of the electric rotating machine 700. However, at the grounded side 708 (driving end, DE) of the conventional electric rotating machine 700, which has an electrically conductive bearing 704, negative bearing currents still arise, such as in the form of capacitive-type currents 710 schematically illustrated in figure 1 . One of the objects of embodiments of the present invention is to avoid or mitigate said capacitive-type currents. The dotted line 718 in figure 1 represents a conventional output and returning electric current via a PWM VFD inverter / converter 720. Conventionally, the rotor shaft 705 may be connected to a gearbox 722.

[0041] With reference to figures 2 to 6, aspects of embodiments of the electric rotating machine 400 according to the first aspect of the invention are schematically illustrated.

[0042] With reference to figures 2 and 3, the electric rotating machine 400 comprises a stator 404 and a rotor 100 rotatable in relation to the stator 404. The rotor 100 comprises a rotor shaft 102 configured to rotate together with the rotor 100 about an axis of rotation 104 in relation to the stator 404. The rotor shaft 102 comprises a shell 126 and an inner section 128. The shell 126 houses the inner section 128. The shell 126 and the inner section 128 are configured to rotate together with the rotor shaft 102. The rotor shaft 102 forms, or comprises, an internal compartment 122, for example an annular internal compartment 122, such as an annular gap 124, for guiding a cooling fluid. The internal compartment 122 is formed between the inner section 128 and the shell 126. The electric rotating machine 400 comprises a discharge arrangement 600 for discharging, or dissipating, an electrical charge and / or a voltage from the rotor shaft 102. The discharge arrangement 600 comprises a first contact device 602 for direct or indirect electrical contact with a second contact device 604. The first contact device 602 is rotatable in relation to the second contact device 604. The inner section 128 is electrically connected to the rotor shaft 102. The first contact device 602 comprises a portion of the inner section 128.

[0043] For some embodiments, it may be defined that the first contact device 602 is, or consists of, a portion of the inner section 128. For some embodiments, it may be defined that the first contact device 602 is configured for direct electrical contact with the second contact device 604.

[0044] For some embodiments, it may be defined that the first contact device 602 is configured for indirect electrical contact with the second contact device 604. For some embodiments, the first contact device 602 may comprise one or more intermediate contact elements for direct or indirect electrical contact with the second contact device 604. The one or more intermediate contact elements may be configured to be positioned between said portion of the inner section 128 and the second contact device 604. For some embodiments, it may be defined that the one or more intermediate contact elements is / are electrically connected to the said portion of the inner section 128. For some embodiments, it may be defined that the one or more intermediate contact elements is / are direct or indirect attached to said portion of the inner section 128. For some embodiments, the intermediate contact element may be formed as a cup or socket, for example for receiving and accommodating at least a portion of the second contact device 604. The one or more intermediate contact elements may be made of an electrically conductive material, such as a material comprising or consisting of a metal or a metal alloy, for example aluminum, or any other metal, metal alloy or material.

[0045] With reference to figures 2 and 3, for some embodiments, it may be additionally defined that the first contact device 602 makes, or is configured to make, physical or mechanical contact with the second contact device 604. For some embodiments, the discharge arrangement 600 may be described, or referred to, as a low impedance path arrangement, a grounding contact arrangement, or a grounding arrangement. The discharge arrangement 600 provides grounding of the rotor shaft 102 and / or of any bearing currents mentioned above.

[0046] With reference to figures 2 and 3, for some embodiments, the first contact device 602 may be rotatable about the axis of rotation 104 in relation to the second contact device 604.

[0047] With reference to figures 2 and 3, for some embodiments, it may be defined that the inner section 128 has an outer surface 114, that the first contact device 602 comprises a contact surface 606 for the electrical contact with the second contact device 604, and that the contact surface 606 of the first contact device 602 comprises, or is (or consists of), a portion of the outer surface 114 of the inner section 128. For some embodiments, it may be defined that the axis of rotation 104 extends through the contact surface 606 of the first contact device 602.

[0048] With reference to figure 3, for some embodiments, the first contact device 602 may comprise a recess 608, or compartment, or depression, formed by the inner section 128. The first contact device 602 may be configured to receive and accommodate at least a portion of the second contact device 604 in the recess 608 of the first contact device 602. For some embodiments, it may be defined that the recess 608 opens in a direction 112 in parallel to the axis of rotation 104. For some embodiments, it may be defined that the inner section 128 has an outer surface 114 and that the inner section 128 forms, or comprises, the recess 608 of the first contact device 602 at the outer surface 114 of the inner section 128. With reference to figure 2, for some embodiments, it may be defined that the inner section 128 comprises a first end portion 106 and a second end portion 108, that the inner section 128 has a longitudinal extension 110 extending from the first end portion 106 to the second end portion 108, and that the longitudinal extension 110 of the inner section 128 extends in a direction 112 in parallel to the axis of rotation 104. For some embodiments, it may be defined that the first contact device 602 comprises a portion of the first end portion 106. For some embodiments, it may be defined that the first contact device 602 is, or consists of, a portion of the first end portion 106.

[0049] With reference to figure 3, for some embodiments, the discharge arrangement 600 may comprise one or more bearings 610 attached to the first contact device 602. The one or more bearings 610 of the discharge arrangement 600 may be configured to at least partially support the second contact device 604.

[0050] For some embodiments, the discharge arrangement 600 may comprise the second contact device 604.

[0051] With reference to figure 3, for some embodiments, the second contact device 604 may comprise an electrically conductive and elongated grounding device 612 having a longitudinal extension 614 extending in a direction 112 in parallel to the axis of rotation 104. For some embodiments, the electrically conductive and elongated grounding device 612 may be referred to, or described, as a grounding pin.

[0052] With reference to figure 3, for some embodiments, the second contact device 604 may comprise an electrically conductive contact member 616 for the electrical contact, such as the direct or indirect electrical contact, with the first contact device 602. At least the contact member 616 is movable in a direction 112 in parallel to the axis of rotation 104 in relation to the first contact device 602. The discharge arrangement 600 may comprise a biasing arrangement 618 for urging, or forcing, the contact member 616 in a direction toward the first contact device 602. The biasing arrangement 618 may comprise a spring, such as helical spring, or any other spring. One or more of the elongated grounding device 612 and contact member 616 may be made of aluminum, or a metal alloy including aluminum, or any other electrically conductive material. With reference to figures 2 and 4, for some embodiments, it may be defined that the electric rotating machine 400 comprises a casing 440 housing at least the rotor 100 and the discharge arrangement 600. The discharge arrangement 600 may be configured to discharge an electrical charge and / or a voltage from the rotor shaft 102 to a first section 442 of the casing 440 via the first and second contact devices 602, 604. One or more of the first section 442 and casing 440 may be grounded. For some embodiments, the casing 440 may be referred to as a casing of a propulsion system, to which the electric rotating machine 400 belongs or is associated with. For some embodiments, it may be defined that the first contact device 602 is electrically connectable, or connected, to the first section 442 of the casing 440 via the second contact device 604.

[0053] With reference to figures 2 and 4, for some embodiments, it may be defined that the electric rotating machine 400 comprises one or more bearings 406a; 406b for supporting the rotor shaft 102, for example two more bearings 406a; 406b, such as two bearings 406a, 406b. A non-driving end (NDE) 450 of the electric rotating machine 400 may be electrically insulated, for example by providing the one 406a of the two more bearings 406a; 406b at the non-driving end (NDE) 450 as a hybrid bearing 406a, which, for example, may include bearing balls made of a ceramic material. The driving end (DE) 452 of the electric rotating machine 400 may be grounded by way of the discharge arrangement 600.

[0054] With reference to figures 2 and 4, for some embodiments, the discharge arrangement 600 may be described as a grounding arrangement for electrically connecting the rotor shaft 102 to a first section 442 of the casing 440 by a low impedance path in order to equalize the voltage potential of the rotor shaft 102. For some embodiments, the first section 442 of the casing 440 may be described, or defined, as a casing component of a propulsion system, to which the electric rotating machine 400 belongs or is associated with. The first section 442 of the casing 440 may be grounded.

[0055] With reference to figure 2, for some embodiments, the electrically conductive and elongated grounding device 612 may extend inside a hollow shaft 454 of an oil pump 456 of the propulsion system. For some embodiments, the electrically conductive and elongated grounding device 612 may extend through the bearing 462 of a gearbox.

[0056] Having a configuration of a propulsion system as disclosed in figure 4, where the electric rotating machine 400 is fitted between an input shaft 458 on the driving end (DE) 452 and a power take-off (PTO) 460 for auxiliary systems on the non-driving end (NDE) 450, there is limited space for conventional equipment regarding the grounding of the rotor shaft 102 and for contact with the rotor shaft 102, for example in vehicles, since the power take-off (PTO) 460 and the input shaft 458 block axial access to the rotor shaft 102 from both ends. Embodiments of the innovative discharge arrangement 600 overcome the issues regarding limited space and space constraints.

[0057] It is to be understood that the second contact device 604 may be designed or structured in several other ways different from what is illustrated in figures 2 and 3 and that the first contact device 602 may be designed or structured in several other ways different from what is illustrated in figures 2 and 3.

[0058] With reference to figure 2, for some embodiments, the shell 126 of the rotor shaft 102 may be described as an outer shell. The inner section 128 may be cylindrical or tubular and / or may have a cylindrical surface. For some embodiments, the inner section 128 may be described as an inner element, member, structure or insert. For some embodiments, the inner section 128 may have an outer surface 114, and the shell 126 may have an inner surface, wherein the internal compartment 122 may be formed between the outer surface 114 of the inner section 128 and the inner surface of the shell 126. The inner surface of the shell 126 may be described to face the axis of rotation 104. The outer surface 114 of the inner section 128 may be described to face away from the axis of rotation 104. It may be defined that the inner section 128 is made of an electrically conductive material, such as a material comprising or consisting of a metal or a metal alloy, for example aluminum, or any other metal, metal alloy or material.

[0059] As schematically illustrated in figures 1 , 5 and 6, the rotor 100 may include an annular outer section 250, or annular rotor core, for electromechanical (or magnetic) interaction with the stator 404. The annular outer section 250 may be attached to the rotor shaft 102 and configured to rotate together with the rotor shaft 102. The inner section 128 may be electrically connected to the annular outer section 250. For some embodiments, the annular outer section 250 may comprise one or more elements 258 for the electromechanical (or magnetic) interaction with the stator 404. For some embodiments, each element 258 may be a permanent magnet. Further, the embodiment of the annular outer section 250 is also schematically illustrated in isolation in figure 6. The annular outer section 250 may be mounted to the rotor shaft 102 in several conventional manners.

[0060] With reference to figure 1 , the stator 404 may include one or more stator windings, or one or more other elements interacting with the rotor 100. The one or more stator windings may include one or more end windings. The stator 404 may be annular. The stator 404 may surround the rotor 100. It may be defined that the stator 404 is spaced from the rotor 100 to form a gap 410 between the stator 404 and the rotor 100, such as an annular gap 410. The rotor 100 may include one or more permanent magnets. Thus, the electric rotating machine 400 may be a permanent magnet, PM, machine. However, for alternative embodiments, the electric rotating machine 400 be configured for and operate according to other electrical operation schemes for electric rotating machines. For example, for alternative embodiments, the rotor 100 may include one or more rotor windings, or one or more other elements interacting with the stator 404. Various conventional electrical operation schemes for conventional electric rotating machines are known to the skilled person and are thus not discussed herein in further detail.

[0061] With reference to figure 7, the electric rotating machine 400 may include, or be connected / connectable to, a fluid cooling system 420 for cooling one or more of the rotor 100 and stator 404. The cooling fluid of the fluid cooling system 420 may comprise or consist of one or more of the group of: a liquid; a gas; and a gas mixture. The liquid may comprise or consist of an oil or an oil mixture. Thus, a cooling fluid of the fluid cooling system 420 may be an oil or an oil mixture. With reference to figures 2 and 7, the fluid cooling system 420 may include the internal compartment 122 of the rotor shaft 102 and additional channels (not illustrated) for guiding a cooling fluid, for example to and from the stator 404 and / or the rotor 100. The fluid cooling system 420 may include one or more conduits 426, or lines, for guiding a cooling fluid, for example to or from the rotor 100 and / or stator 404. The fluid cooling system 420 may include a fluid collector and provider 428, for example a fluid collecting tray or vessel, or a fluid sump. For some embodiments, the fluid collector and provider 428 may be fluidly connected to the rotor 100 and / or stator 404 via a heat exchanger 430.

[0062] With reference to figure 8, an embodiment of the vehicle 500 according to the second aspect of the invention is schematically illustrated. The vehicle 500 includes one or more electric rotating machines 400 according to any one of the embodiments disclosed above or below. The one or more electric rotating machines 400 may comprise one or more electric motors 402 and / or one or more electric generators 402. For example, the one or more electric motors 402 may be configured for propelling the vehicle 500. For example, one or more electric generators 402 may be configured for charging one or more electrical battery arrangements 506 and / or one or more electric battery packs 510 of the vehicle 500.

[0063] With reference to figure 8, the vehicle 500 is illustrated as a tractor vehicle. However, in other embodiments, the vehicle 500 may, for example, be a bus, a truck, a heavy truck or a car. Other types of vehicles are also possible. The vehicle 500 may be an electric vehicle, EV, for example a hybrid vehicle or a hybrid electric vehicle, HEV, or a battery electric vehicle, BEV.

[0064] With reference to figure 8, the vehicle 500 may be a wheeled vehicle, i.e. a vehicle 500 having wheels 502. Only the wheels 502 on the left-hand side of the vehicle 500 are visible in figure 8. It is to be understood that the vehicle 500 may have fewer or more wheels than what is shown in figure 8. The vehicle 500 may comprise a powertrain 504, for example configured for one of an EV, HEV and BEV. The vehicle 500 may be configured to hold or carry, or may include, one or more electrical battery arrangements 506 including two or more electric battery cells 508. The vehicle 500 may be configured to hold or carry, or may include, one or more electric battery packs 510 including two or more electric battery cells 508 and / or including two or more electrical battery arrangements 506, which may be referred to as modules. The electrical battery arrangement 506 and / or the electric battery pack 510 may, for example, be attachable to a chassis 512 of the vehicle 500. It is to be understood that the vehicle 500 may include further units, components, such as electrical and / or mechanical components, a combustion engine 514 and other devices required for a vehicle 500, such as for an EV, HEV or BEV.

[0065] With reference to figure 8, it may be defined that the powertrain 504 and / or the one or more electric rotating machines 400 is / are configured to propel, or drive, the vehicle 500. It may be defined that the powertrain 504 includes the electrical battery arrangement 506 and / or the electric battery pack 510. The one or more electric rotating machines 400 may be located at locations different from what is illustrated in figure 8, for example in connection with the combustion engine 514, for example acting as an electric generator.

[0066] With reference to figure 8, the vehicle 500 may include a vehicle electrical system 516. It may be defined that the vehicle electrical system 516 is configured for direct current. It may be defined that vehicle electrical system 516 is a vehicle high voltage system 516. It may be defined that the vehicle high voltage system 516 is configured for a high voltage, such as a voltage above 60 V, for example above 400 V, or above 450 V, such as above 650 V. For example, the vehicle high voltage system 516 may be configured for a voltage up to 1500 V and / or for a voltage above 1500 V. The electric power, or the electric current, for example the direct current, of the vehicle electrical system 516 may be transferred at a high voltage, for example at one or more of the voltages levels mentioned above. The vehicle electrical system 516 may be configured to transfer the electric power, or the electric current, at a high voltage, for example at one or more of the voltages levels mentioned above. The vehicle electrical system 516 may be configured to transfer direct current.

[0067] With reference to Figure 8, the vehicle electrical system 516 may be electrically connected, or connectable, to one or more electrical battery arrangements 506 and / or one or more electric battery packs 510. It may be defined that the electrical battery arrangement 506 and / or the electric battery pack 510 is / are configured for high voltage, for example for one or more of the voltages levels mentioned above. The vehicle electrical system 516 may be configured to electrically connect the electrical battery arrangement 506 and / or the electric battery pack 510 to the powertrain 504 of the vehicle 500. The vehicle electrical system 516 may be configured to electrically connect the electrical battery arrangement 506 and / or the electric battery pack 510 to the one or more electric rotating machines 400 of the vehicle 500. It may be defined that the vehicle electrical system 516 is configured to transfer the electric power, or the electric current, for example between the one or more electric rotating machines 400 (and / or the powertrain 504) and the electrical battery arrangement 506 and / or the electric battery pack 510.

[0068] It is to be understood that embodiments of the electric rotating machine 400 may be applied to configurations, structures, or apparatuses different from a vehicle 500.

[0069] The present invention is not limited to the above-described embodiments. Instead, the present invention relates to, and encompasses all different embodiments being included within the scope of the independent claim.

Claims

1. Claims1. An electric rotating machine (400) comprising a stator (404) and a rotor (100) rotatable in relation to the stator (404), wherein the rotor (100) comprises a rotor shaft (102) configured to rotate together with the rotor (100) about an axis of rotation (104) in relation to the stator (404), wherein the rotor shaft (102) comprises a shell (126) and an inner section (128), wherein the shell (126) houses the inner section (128), wherein the shell (126) and the inner section (128) are configured to rotate together with the rotor shaft (102), wherein the rotor shaft (102) forms an internal compartment (122) for guiding a cooling fluid, wherein the internal compartment (122) is formed between the inner section (128) and the shell (126), wherein the electric rotating machine (400) comprises a discharge arrangement (600) for discharging an electrical charge and / or a voltage from the rotor shaft (102), wherein the discharge arrangement (600) comprises a first contact device (602) for direct or indirect electrical contact with a second contact device (604), wherein the first contact device (602) is rotatable in relation to the second contact device (604), wherein the inner section (128) is electrically connected to the rotor shaft (102), and wherein the first contact device (602) comprises a portion of the inner section (128).

2. An electric rotating machine (400) according to claim 1 , wherein the first contact device (602) is rotatable about the axis of rotation (104) in relation to the second contact device (604).

3. An electric rotating machine (400) according to claim 1 or 2, wherein the inner section (128) has an outer surface (114), wherein the first contact device (602) comprises a contact surface (606) for the electrical contact with the second contact device (604), wherein the contact surface (606) of the first contact device (602) comprises a portion of the outer surface (114) of the inner section (128).

4. An electric rotating machine (400) according to claim 3, wherein the axis of rotation (104) extends through the contact surface (606) of the first contact device (602).

5. An electric rotating machine (400) according to any one of the claims 1 to 4, wherein the first contact device (602) comprises a recess (608) formed by the inner section (128), and wherein the first contact device (602) is configured to receive and accommodate at least a portion of the second contact device (604) in the recess (608) of the first contact device (602).

6. An electric rotating machine (400) according to claim 5, wherein the recess (608) opens in a direction (112) in parallel to the axis of rotation (104).

7. An electric rotating machine (400) according to any one of the claims 1 to 6, wherein the inner section (128) comprises a first end portion (106) and a second end portion (108), wherein the inner section (128) has a longitudinal extension (110) extending from the first end portion (106) to the second end portion (108), wherein the longitudinal extension (110) of the inner section (128) extends in a direction (112) in parallel to the axis of rotation (104), and wherein the first contact device (602) comprises a portion of the first end portion (106).

8. An electric rotating machine (400) according to any one of the claims 1 to 7, wherein the discharge arrangement (600) comprises one or more bearings (610) attached to the first contact device (602), and wherein the one or more bearings (610) of the discharge arrangement (600) is / are configured to at least partially support the second contact device (604).

9. An electric rotating machine (400) according to any one of the claims 1 to 8, wherein the discharge arrangement (600) comprises the second contact device (604), and wherein the second contact device (604) comprises an electrically conductive and elongated grounding device (612) having a longitudinal extension (614) extending in a direction (112) in parallel to the axis of rotation (104).

10. An electric rotating machine (400) according to any one of the claims 1 to 9, wherein the discharge arrangement (600) comprises the second contact device (604), wherein the second contact device (604) comprises an electrically conductive contact member (616) for the electrical contact with the first contact device (602), wherein at least the contact member (616) is movable in a direction (112) in parallel to the axis of rotation (104) in relation to the first contact device (602), and wherein the discharge arrangement (600) comprises a biasing arrangement (618) for urging the contact member (616) in a direction toward the first contact device (602).

11. An electric rotating machine (400) according to any one of the claims 1 to 10, wherein the electric rotating machine (400) comprises a casing (440) housing at least the rotor (100) and the discharge arrangement (600), and wherein the discharge arrangement (600) is configured to discharge an electrical charge and / or a voltage from the rotor shaft (102) to a first section (442) of the casing (440) via the first and second contact devices (602, 604).

12. An electric rotating machine (400) according to claim 11 , wherein the first contact device (602) is electrically connectable to the first section (442) of the casing (440) via the second contact device (604).

13. An electric rotating machine (400) according to any one of the claims 1 to 12, wherein the electric rotating machine (400) comprises one or more bearings (406a, 406b) for supporting the rotor shaft (102).

14. An electric rotating machine (400) according to any one of the claims 1 to 13, wherein the rotor (100) comprises an annular outer section (250) for electromechanical interaction with the stator (404), wherein the annular outer section (250) is attached to the rotor shaft (102) and configured to rotate together with the rotor shaft (102), and wherein the inner section (128) is electrically connected to the annular outer section (250).

15. A vehicle (500) comprising one or more electric rotating machines (400) according to any one of the claims 1 to 14.

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