Bearing with integrated wireless power transfer device

Abstract

A bearing assembly includes an outer ring connectable with a housing, the outer ring having an outer ring raceway and a transmitting coil axially spaced from the outer ring raceway. The transmitting coil can be electrically connected to a battery and is configured to generate an electromagnetic field when a current flows therethrough. The inner ring can be arranged around a rotating shaft of the rotor and is provided with an inner ring raceway and a receiving coil which is spaced from the inner ring raceway in the axial direction. And the receiving coil is close to the transmitting coil and is in induction connection with the transmitting coil, so that current is generated in the receiving coil when the current flows through the transmitting coil. The receiving coil is connected with an electromagnetic coil of the motor rotor, so that current flows to the electromagnetic coil from the receiving coil. A plurality of rolling bodies are disposed between the outer ring raceway and the inner ring raceway to rotatably connect the outer ring and the inner ring together.

Description

Technical Field

[0001] The present invention relates to both a bearing and a power transmission device, and in particular to a power transmission device of a motor whose rotating shaft is supported by a bearing. Background Art

[0002] Electric motors are well known and include a stator and a rotor. The stator has one or more magnets, typically electromagnets; the rotor is arranged inside the stator, mounted or connected to a shaft (hereinafter also referred to as the "rotor shaft"), and includes one or more magnets. When the rotor magnets are electromagnetic coils (hereinafter also referred to as "rotor coils"), current or power must be supplied to these coils to generate the magnetic field required to interact with the corresponding magnetic field of the stator. Typically, power is supplied to the rotor coils via one or more fixed conductors and a rotatable conductor. The fixed conductor is electrically connected to a power source (for example, a battery), and the rotatable conductor is mounted on the shaft, electrically connected to the rotor coil, and contacted by the fixed conductor.

[0003] As the rotor shaft angularly displaces about its central axis, the rotatable conductors slide against the stationary conductors, continuously delivering current from the power source to the rotor coils. This sliding action causes both the stationary and rotatable conductors to wear, which can weaken or even completely cut off the power transmission between the conductors, thereby reducing or stopping the current flow to the rotor coils. Furthermore, debris or contaminants can accumulate or become lodged at the interfaces between the conductors, reducing or stopping the current flow to the rotor. Furthermore, the sliding contact between the conductors increases the frictional load on the rotor shaft.

[0004] Because of these potential issues, typical electric motors used in electric vehicles have rotors with permanent magnets, eliminating the need to supply current to the rotor. While this power supply system is relatively robust, the permanent magnets required to generate the torque needed to propel the electric vehicle are typically quite large, significantly adding weight to the vehicle. Furthermore, these large permanent magnets are often made from rare earth elements such as neodymium, terbium, and dysprosium, which can have harmful environmental impacts during mining, processing, and disposal. Summary of the Invention

[0005] In one aspect, the present invention is a bearing assembly having a power transmission device for transmitting power from a battery to an electric motor. The electric motor includes a housing, an external stator connected to the housing, and a rotor disposed within the stator. The rotor is mounted on a shaft, rotatable about a central axis passing through the shaft, and includes at least one electromagnetic coil. The bearing assembly includes an outer ring connectable to the housing and an inner ring disposed about the shaft. The outer ring has an outer raceway and a transmitting coil axially spaced from the outer raceway. The transmitting coil is electrically connectable to a battery and configured to generate an electromagnetic field when current flows therethrough. The inner ring has an inner raceway and a receiving coil axially spaced from the inner raceway. The receiving coil is positioned proximate to the transmitting coil and inductively coupled thereto. In this manner, when current flows through the transmitter coil, current is generated in the receiver coil. Furthermore, the receiver coil can be electrically connected to at least one electromagnetic coil on the rotor, allowing current to flow from the receiver coil to the electromagnetic coil. Furthermore, a plurality of rolling elements are disposed between the outer and inner raceways, rotatably coupling the outer and inner raceways, thereby connecting the rotor shaft to the housing.

[0006] On the other hand, the present invention is also a drive motor assembly ( / drive motor assembly / drive motor assembly) for an electric vehicle having at least one wheel. The motor assembly includes a motor, which is configured to drive the at least one wheel in a rotatable manner. The motor has a housing, an external stator connected to the housing, and a rotor located inside the stator. The rotor is mounted on a rotating shaft, can rotate around a central axis passing through the rotating shaft, and has at least one electromagnetic coil. The motor assembly further includes a battery and the bearing assembly with a power transmission device described in the previous paragraph. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The present invention will be better understood by reading the above summary and detailed description of preferred embodiments of the present invention in conjunction with the accompanying drawings. To illustrate the present invention, the drawings show presently preferred schematic embodiments of the present invention. However, it should be understood that the present invention is not limited to the precise arrangements and instrumentalities shown. In the following drawings:

[0008] Figure 1 A schematic diagram showing an overall electric vehicle including a bearing assembly with a power transmission device according to the present invention;

[0009] Figure 2 A block diagram showing certain electronics of the vehicle's drive system, illustrating an exemplary flow of power through the vehicle;

[0010] Figure 3 An axial cross-sectional view of a drive system including the bearing assembly of the present invention is shown, wherein the bearing assembly is assembled around a rotating shaft and connected to a housing of a motor;

[0011] Figure 4 yes Figure 3 A partially enlarged cross-sectional view of ; and

[0012] Figure 5 yes Figure 3 A further enlarged partial cross-sectional view. DETAILED DESCRIPTION

[0013] In the following description, certain terms are used for convenience only and are not intended to be limiting. The terms "upper" and "lower" are used to refer to reference directions in the accompanying drawings, and "inward," "inwardly," and "outwardly" refer to directions toward and away from a designated centerline or geometric center of the described components, respectively, with their specific meanings being apparent from the context of the description. In addition, the terms "connected" and "connected" are used herein to include both a direct connection between two components (without any other components intervening) and an indirect connection between two components (with one or more other components intervening). The terms include the words specifically mentioned above, their derivatives, and words of similar meaning.

[0014] Reference is now made in detail to the drawings, wherein like numerals are used to refer to like parts throughout. Figures 1 to 5 The bearing assembly 10 is shown with an integrated wireless power transmission device 11. The power transmission device 11 preferably transmits power from the battery (preferably a battery pack) 1 to the motor 2 via an electronic power inverter connected to the motor 2. The motor 2 is preferably a drive motor of a four-wheeled electric vehicle V, such as Figure 1 As shown, but it can also be any other suitable type of motor in other cases. The motor 2 has a housing 3, an external stator 4 connected to the housing 3, and a rotor 5 located inside the stator 4. The rotor 5 is mounted on a rotating shaft 6 and can rotate around a central axis A passing through the rotating shaft 6. CRotation. The rotor 5 has at least one, and preferably multiple, electromagnetic coils 7. Generally speaking, the bearing assembly 10 with the power transmission device 11 includes an outer ring 12 having a transmitter coil 14, an inner ring 16 disposed within the outer ring 12 and having a receiver coil 18, and a plurality of rolling elements 20 disposed between the inner and outer rings 16 and 12 to rotatably couple them. During the rotation of the inner ring 16, power is wirelessly transmitted from the transmitter coil 14 to the receiver coil 18, as described in detail below.

[0015] like Figures 3 to 5 As shown, an outer ring 12 is (can be) connected to the housing 3 and has an outer ring raceway 13. A transmitting coil 14 is connected to the outer ring 12 and is axially spaced from the outer ring raceway 13. The transmitting coil 14 is preferably electrically connected to the battery 1 via one or more electronic components (as described below) and is preferably configured to generate an electromagnetic field. An inner ring 16 is (can be) disposed about the shaft 6 and has an inner ring raceway 17. A receiving coil 18 is connected to the inner ring 16 and is axially spaced from the inner ring raceway 17. The receiving coil 18 is positioned adjacent to the transmitting coil 14 and is magnetically coupled to the transmitting coil 14. The receiving coil 18 is electrically connected to at least one electromagnetic coil 7 of the rotor 5 to receive a current generated in the coil 18, which preferably flows to the electromagnetic coil 7 via one or more electronic components described below.

[0016] Specifically, the transmitting coil 14 receives current and generates an electromagnetic field. This electromagnetic field induces a current in the receiving coil 18, a process known as "inductive coupling" and well known in the art of electronics. Therefore, further detailed explanation of coils 14 and 18 is unnecessary for the present invention. In a preferred application for an electric vehicle V, to provide sufficient current to the rotor 5, the transmitting coil 14 is configured (i.e., constructed, dimensioned, etc.) to transmit power within a power range of 100 watts (100 W) to 3 kilowatts (3 kW). Similarly, the receiving coil 18 is configured to receive power within a power range of 100 watts (100 W) to 3 kilowatts (3 kW). However, depending on the specific application of the bearing assembly 10, both coils 14 and 18 may also be configured to have significantly less or greater power transmission capabilities.

[0017] Furthermore, a plurality of rolling elements 20 are disposed between outer ring raceway 13 and inner ring raceway 17, rotatably connecting outer ring 12 and inner ring 16, thereby forming bearing 22. As shown, rolling elements 20 are preferably balls, but may alternatively be cylindrical rollers, tapered rollers, needle rollers, or any other suitable type of rolling element. Rolling elements 20 are conventionally made of steel, but may alternatively be formed of ceramic or other insulating materials to provide insulation between bearing raceways 13 and 17. Although not currently preferred, bearing rings 12 and 16 may alternatively be formed as components of a sliding bearing (as plain bearing rings), with the inner circumferential surface of outer ring 12 slidingly disposed about the outer circumferential surface of inner ring 16. In this case, transmitter coil 14 and receiver coil 18 are preferably disposed on plain bearing rings 12 and 16 (this structure is not shown).

[0018] Preferably, the outer ring 12 includes an annular body (hereinafter also referred to as the "outer ring body") 30. The outer ring body 30 has first and second axial ends 30a and 30b opposite to each other, an inner circumferential surface 32, and an outer circumferential surface 34 opposite to the inner circumferential surface 32. The outer ring raceway 13 extends radially outward from the inner circumferential surface 32 of the outer ring body 30. The transmitting coil 14 is either disposed directly on the inner circumferential surface 32 of the outer ring body 30 or, preferably, is disposed in an annular recess 36 extending radially outward from the inner circumferential surface 32 of the outer ring body 30. Furthermore, the outer circumferential surface 34 of the outer ring body 30 is slidably disposed in the inner bore 8 of the housing 3. For reasons explained later, the outer circumferential surface 34 has an annular groove 35 formed radially inward.

[0019] Similarly, the inner ring 16 includes an annular body (hereinafter also referred to as the "inner ring body") 40. The inner ring body 40 has first and second axial ends 40a and 40b that are opposite to each other, an inner circumferential surface 42, and an outer circumferential surface 44 that is opposite to the inner circumferential surface 42. The inner ring raceway 17 extends radially inward from the outer circumferential surface 44 of the inner ring body 40. The receiving coil 18 is either disposed directly on the outer circumferential surface 44 of the inner ring body 40 or, preferably, is disposed within an annular recess 45 that extends radially inward from the outer circumferential surface 44 of the inner ring body 40. Furthermore, the inner circumferential surface 42 of the inner ring body 40 defines an annular inner ring bore 46 for accommodating a portion of the rotating shaft 6. The inner ring 16 is preferably frictionally engaged with the rotating shaft 6.

[0020] Preferably, the axial length (not labeled) of the inner ring body 40 between its axial ends 40a and 40b is significantly greater than the axial length (not labeled) of the outer ring body 30 between its axial ends 30a and 30b. In this manner, an exterior mounting surface section (hereinafter referred to as "mounting surface section") 48 of the outer circumferential surface 44 of the inner ring body 40 extends between the second axial end 40b and the receiving coil 18. As described below, the mounting surface section 48 provides a mounting surface for certain electronic components connected to the receiving coil 18.

[0021] In a currently preferred embodiment, each of the transmitting coil 14 and the receiving coil 18 is annular in shape, and the receiving coil 18 is coaxially disposed within the transmitting coil 14. Specifically, the transmitting coil 14 includes an annular body 15 having an inner circumferential surface 15a, and the receiving coil 18 includes an annular body 19 having an outer circumferential surface 19a. The outer circumferential surface 19a of the receiving coil 18 is radially spaced apart from (or radially spaced apart from) the inner circumferential surface 15a of the transmitting coil 14 from the radially inner side. In this manner, an annular air gap GA is defined between the two circumferential surfaces 15a and 19a, as shown in FIG. Figure 5 In a preferred embodiment, the dimensions of the transmitting coil 14 and the receiving coil 18 are set so that the radial dimension d of the annular air gap GA is R In terms of value, it does not exceed five millimeters (5 mm), and, preferably, is about one millimeter (1 mm). With such a relatively small or narrow air gap GA, the power transmission device 11 can, as described above, transmit a relatively large amount of power with a relatively high efficiency, preferably an efficiency greater than 95%.

[0022] In another embodiment, the transmitter coil 14 and receiver coil 18 may still be annular but axially spaced apart, with axial end surfaces facing each other (not shown). Alternatively, the transmitter coil 14 and receiver coil 18 may be formed with angled surfaces facing each other, spaced apart both radially and axially. Furthermore, the transmitter coil 14 and receiver coil 18, as well as their supporting electronics, may be configured or arranged to provide bidirectional transmission of signals or data. For example, data collected by sensors may be transmitted from the rotor 5 to a non-rotating component (e.g., a motor controller, a vehicle computer, etc.) to provide information about the rotor 5 (e.g., temperature) to a vehicle control system (not shown). As another example, the vehicle control system (not shown) may provide instructions for adjusting the rectifier system (not shown) by sending data or commands from the transmitter coil 14 to the receiver coil 18. In this case, the receiver coil 18 is connected to the rectifier system. The scope of the present invention includes all of these disclosed configurations of coils 14, 18, as well as any other suitable configuration that can be disposed within (or on) bearing rings 12, 16 and that can perform the functions described herein.

[0023] Now see Figure 2 、 Figure 4 and Figure 5 The battery 1 provides direct current (DC), and the electromagnetic coils 7 of the rotor 5 preferably also require DC power. However, the transmitting coil 13 requires alternating current (AC) to generate AC power within the receiving coil 18. Therefore, the power transmission device 11 further includes a direct current (DC-to-AC) power converter 50 and an alternating current (AC-to-DC) power converter 52. The DC-to-AC power converter 50 is preferably mounted on the housing 3, while the AC-to-DC power converter 52 is preferably mounted on the inner ring 16. Specifically, the DC-to-AC power converter 50 is electrically connected to the battery 1 and the transmitting coil 14, for example, via wires 54. The wires 54 can be hard-wired or removably connected (e.g., a plug-and-socket connection). The DC-to-AC power converter 50 is configured to convert the DC power from the battery 1 into AC power, which is then transmitted to the transmitting coil 14. Preferably, the DC-AC power converter 50 is provided on a printed circuit board (PCB) 56 that is (can be) connected to the housing 3. Most preferably, the printed circuit board 56 is mounted on a retaining plate 60 of a bearing, as described below.

[0024] Furthermore, an AC-DC power converter 52 is preferably disposed on the mounting surface portion 48 of the inner ring 16 and is electrically connected to the receiving coil 18 and (can be) electrically connected to the at least one electromagnetic coil 7 of the rotor 5, for example, via wires 54 or any other suitable means. The AC-DC power converter 52 is configured to convert the alternating current generated in the receiving coil 18 into direct current that can be supplied to the electromagnetic coil 7. Preferably, the AC-DC power converter 52 is disposed on a printed circuit board (PCB) 58A, which is mounted on the inner ring 16, preferably on the mounting surface portion 48 of the inner ring 16. The PCB 58A is preferably formed as a "horseshoe-shaped" PCB with a rectifier system and is secured to the mounting surface portion 48 by an annular retainer 59A. The annular retainer 59A is engaged with the mounting surface portion 48, for example, by friction, threads, or a keyed fit. Furthermore, the AC-DC power converter 52 is electrically connected to the electromagnetic coil 7 by any suitable means, such as two wires 54 (only one of which is shown). The wires 54 may be hard-wired or removably connected (e.g., via detachable contacts). Furthermore, the bearing assembly 10 may include a second printed circuit board 58B disposed on the mounting surface 48 of the inner ring 16. The second printed circuit board 58B is retained by a second annular retainer 59B and serves to provide additional functionality for the bearing assembly 10.

[0025] Now see Figures 3 to 5 As mentioned above, the bearing outer ring 12 is preferably slidably disposed in the inner bore 8 of the housing 3 so as to allow the outer ring 12 to be displaced in the axial direction, thereby adapting to the thermal expansion of the rotating shaft 6 through adjustment. Specifically, the inner bore 8 has an inner circumferential surface 8a, and the housing 3 further includes a radial shoulder 3a extending radially inward from the inner bore 8. The bearing outer ring 12 is disposed in the inner bore 8 so that its outer circumferential surface 34 slidably abuts against the inner circumferential surface 8a of the inner bore 8. In addition, the housing 3 also preferably includes an annular retaining disk 60, which is connected to the radial end face 3b of the housing 3. The annular retaining disk 60 has a radial inner end 62 and can be disposed in the annular groove 35 of the outer ring body 30 to retain the outer ring 12 in the inner bore 8 of the housing 3 while allowing the outer ring 12 to be displaced axially, as shown in FIG. Figure 5 Preferably, the printed circuit board 50 is mounted on the retaining plate 60 by any suitable means, such as, for example, by one or more threaded fasteners 64 as shown.

[0026] Furthermore, the bearing assembly 10 further includes at least one biasing member 66 disposed within the inner bore 8 of the housing 3. The biasing member 66 has a first axial end 66a that abuts the housing radial shoulder 3a and a second axial end 66b that abuts the first axial end 30a of the outer ring 12. Each biasing member 66 is configured to apply an axial force toward the retaining plate 60 against the first axial end 30a of the outer ring body 30. In this manner, the bearing outer ring 12 is capable of limited axial displacement so that an appropriate preload is always established within the rolling elements 20. Preferably, the at least one biasing member 66 is a single wave spring (not shown), but in other cases, it may include multiple coil springs (as shown), a solid elastomeric member, or the like. Alternatively, however, the bearing outer ring 12 may be fixedly mounted within the housing inner bore 8, for example, by frictional engagement between the inner circumferential surface 8a of the inner bore 8 and the outer circumferential surface 34 of the bearing outer ring 12.

[0027] The bearing assembly 10 of the present invention offers numerous advantages over previously known motor bearings and power transmission devices for delivering current to a motor rotor. By incorporating the power transmission device 11 into the bearing assembly 10, power transmission components, such as the transmitter coil 14 and receiver coil 18, and power converters 50 and 52, are assembled simultaneously with the bearing 22 supporting the rotor shaft 6. This eliminates the need for separate assembly of the power components, reducing the axial space required for them. Furthermore, compared to power transmission using contact conductors, supplying power from the battery 1 to the rotor 5 via the wireless power transmission device 11 reduces frictional loads on the shaft 6 and significantly improves power transmission reliability and power density. Furthermore, the transmitter coil 14 and receiver coil 18 are enclosed within the bearing rings 12 and 16, providing a significant degree of protection for these components 14 and 18 while eliminating the need for separate housings.

[0028] The above describes in detail representative non-limiting embodiments of the present invention with reference to the accompanying drawings. This detailed description is only to teach those skilled in the art to implement further details of the preferred aspects of the present invention, and is not intended to limit the scope of the present invention.

[0029] In addition, the combination of features and steps disclosed in the above detailed description may not be necessary to implement the invention in the broadest sense, but are only particularly described for the purpose of teaching (representative embodiments of the invention). In addition, various features of the above representative embodiments and the various independent and dependent claims attached hereto may also be combined in ways not specifically enumerated to provide additional useful embodiments of the invention.

[0030] All features disclosed in the specification and / or claims are disclosed separately and independently for the purposes of original written disclosure and for the purposes of limiting the claimed subject matter, regardless of the combination of features in the examples and / or claims. Furthermore, all numerical ranges or representations of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purposes of original written disclosure and for the purposes of limiting the claimed subject matter. The present invention is not limited to the embodiments described above and may be varied within the scope of the appended claims.

Claims

1. A bearing assembly having a power transmission device for transmitting power from a battery to a motor, the motor having a housing, an external stator connected to the housing, and a rotor disposed within the stator. The rotor is mounted on a rotating shaft and is rotatable about a central axis passing through the rotating shaft. The rotor has at least one electromagnetic coil. The bearing assembly includes: an outer ring connectable to the housing, having an outer ring raceway and a transmitting coil axially spaced apart from the outer ring raceway, the transmitting coil being electrically connectable to a battery and configured to generate an electromagnetic field when current flows therethrough; an inner ring disposed within the outer ring, capable of being arranged around the rotating shaft and having an inner ring raceway and a receiving coil axially spaced apart from the inner ring raceway, such that the receiving coil is located adjacent to the transmitting coil and is inductively coupled to the transmitting coil such that current is generated in the receiving coil when current flows through the transmitting coil, and the receiving coil is electrically connectable to the at least one electromagnetic coil of the rotor such that current flows from the receiving coil to the electromagnetic coil; and A plurality of rolling elements disposed between the outer ring raceway and the inner ring raceway rotatably couple the outer ring and the inner ring, thereby coupling the rotating shaft to the housing.

2. The bearing assembly according to claim 1, wherein: The transmitting coil is annular and has an inner circumferential surface. The receiving coil is annular and is arranged inside the transmitting coil and has an outer circumferential surface. An annular air gap is defined between the inner circumferential surface of the transmitting coil and the outer circumferential surface of the receiving coil.

3. The bearing assembly according to claim 2, wherein: The transmitting coil and the receiving coil are each dimensioned such that the annular air gap has a radial dimension not exceeding a value of 5 mm.

4. The bearing assembly according to claim 1, wherein: The transmitting coil is configured to transmit an amount of electrical power ranging from 100 watts to 3 kilowatts, and the receiving coil is configured to receive an amount of electrical power ranging from 100 watts to 3 kilowatts.

5. The bearing assembly according to claim 1, wherein: The outer ring has an inner circumferential surface, the outer ring raceway extends radially outward from the inner circumferential surface of the outer ring, and the transmitting coil is arranged on the inner circumferential surface of the outer ring, or is arranged in an annular recess extending radially outward from the inner circumferential surface of the outer ring; The inner ring has an outer circumferential surface, the inner ring raceway extends radially inward from the outer circumferential surface of the inner ring, and the receiving coil is arranged on the outer circumferential surface of the inner ring or in an annular recess extending radially inward from the outer circumferential surface of the inner ring.

6. The bearing assembly according to claim 1, wherein: The bearing assembly further includes a DC-AC power converter mounted on the housing. The DC-AC power converter is electrically connectable to the battery and the transmitting coil, and is configured to convert DC power from the battery into AC power and then transmit the AC power to the transmitting coil.

7. The bearing assembly according to claim 6, wherein: The DC-AC power converter is arranged on a printed circuit board that can be connected to the housing.

8. The bearing assembly according to claim 1, wherein: The bearing assembly further includes an AC-DC power converter mounted on the inner ring, the AC-DC power converter being electrically connected to the receiving coil and also being electrically connectable to the at least one electromagnetic coil of the motor, and being configured to convert the AC power generated in the receiving coil into DC power that can be transmitted to the electromagnetic coil.

9. The bearing assembly according to claim 8, wherein: The AC-DC power converter is provided on a printed circuit board mounted on the inner ring.

10. The bearing assembly according to claim 1, wherein: The outer ring can be slidably disposed in the inner hole of the housing.

11. A drive motor assembly for an electric vehicle having at least one wheel, the motor assembly comprising: a motor configured to rotatably drive the at least one wheel, the motor comprising a housing, an external stator connected to the housing, and a rotor disposed within the stator, the rotor being mounted on a rotating shaft and rotatable about a central axis passing through the rotating shaft, and comprising at least one electromagnetic coil; Batteries; and A bearing assembly having a power transmission device for transmitting power from a battery to a motor, comprising: an outer ring connectable to the housing, having an outer ring raceway and a transmitting coil axially spaced apart from the outer ring raceway, the transmitting coil being electrically connectable to a battery and configured to generate an electromagnetic field when current flows therethrough; an inner ring disposed within the outer ring, arranged around the rotating shaft, and having an inner ring raceway and a receiving coil spaced axially from the inner ring raceway, such that the receiving coil is located adjacent to the transmitting coil and is inductively coupled to the transmitting coil such that current is generated in the receiving coil when current flows through the transmitting coil, and the receiving coil is electrically connectable to the at least one electromagnetic coil of the rotor such that current flows from the receiving coil to the electromagnetic coil; and A plurality of rolling elements disposed between the outer ring raceway and the inner ring raceway rotatably connect the outer ring and the inner ring so as to rotatably couple the rotating shaft to the housing.

12. The motor assembly according to claim 11, wherein: The transmitting coil is annular and has an inner circumferential surface. The receiving coil is annular and is arranged inside the transmitting coil and has an outer circumferential surface. An annular air gap is defined between the inner circumferential surface of the transmitting coil and the outer circumferential surface of the receiving coil.

13. The motor assembly according to claim 12, wherein: The transmitting coil and the receiving coil are each dimensioned such that the annular air gap has a radial dimension not exceeding a value of 5 mm.

14. The motor assembly according to claim 11, wherein: The transmitting coil is configured to transmit an amount of electrical power ranging from 100 watts to 3 kilowatts, and the receiving coil is configured to receive an amount of electrical power ranging from 100 watts to 3 kilowatts.

15. The motor assembly according to claim 11, wherein: The outer ring has an inner circumferential surface, the outer ring raceway extends radially outward from the inner circumferential surface of the outer ring, and the transmitting coil is arranged on the inner circumferential surface of the outer ring, or is arranged in an annular recess extending radially outward from the inner circumferential surface of the outer ring; The inner ring has an outer circumferential surface, the inner ring raceway extends radially inward from the outer circumferential surface of the inner ring, and the receiving coil is arranged on the outer circumferential surface of the inner ring or in an annular recess extending radially inward from the outer circumferential surface of the inner ring.

16. The motor assembly according to claim 11, wherein: The bearing assembly further includes a DC-AC power converter mounted on the housing. The DC-AC power converter is electrically connectable to the battery and the transmitting coil, and is configured to convert DC power from the battery into AC power and then transmit the AC power to the transmitting coil.

17. The motor assembly according to claim 16, wherein: The DC-AC power converter is arranged on a printed circuit board that can be connected to the housing.

18. The motor assembly according to claim 11, wherein: The bearing assembly further includes an AC-DC power converter mounted on the inner ring, the AC-DC power converter being electrically connected to the receiving coil and also being capable of being electrically connected to the at least one electromagnetic coil of the motor, and being configured to convert the AC power generated in the receiving coil into DC power that can be transmitted to the electromagnetic coil.

19. The motor assembly according to claim 18, wherein: The AC-DC power converter is provided on a printed circuit board mounted on the inner ring.

20. The motor assembly according to claim 11, wherein: The outer ring can be slidably disposed in the inner hole of the housing.

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