Energy transmission device and an electrical machine with an energy transmission device

Abstract

Energy transmission device (6) for contactless transmission of electrical energy, comprising a primary coil device (7) and a secondary coil device (8) rotatably mounted about an axis of rotation (4) with respect to the primary coil device (7), wherein the primary coil device (7) has a primary yoke element (9), several primary leg elements (10, 11) and a primary winding (12) and the secondary coil device (8) has a secondary yoke element (13), several secondary leg elements (14, 15) and a secondary winding (16), wherein the primary yoke element (9) and / or the secondary yoke element (13) each consist of a laminated core, and wherein - viewed in longitudinal section with respect to the axis of rotation (4) - the primary yoke element (9) bears against at least one of the primary leg elements (10, 11) and / or the secondary yoke element (13) against at least one of the secondary leg elements (14, 15) along a butt edge (22, 23, 26, 27), where the butt edge (22,23,26,27) and / or its longitudinal center axis (24, 25, 28, 29) is inclined with respect to the axis of rotation (4), characterized in that - viewed in longitudinal section - the butt edge (22, 23, 26, 27) is stepped, and that the primary leg elements (10, 11) and / or the secondary leg elements (14, 15) each consist of a laminated core and have several laminated core parts (30) with a radially extending radial slot, wherein the laminated core parts (30) are arranged one another such that the radial slots of the several laminated core parts (30) are arranged circumferentially offset from one another.

Description

[0001] The invention relates to an energy transmission device for the contactless transmission of electrical energy, comprising a primary coil assembly and a secondary coil assembly rotatably mounted about an axis of rotation relative to the primary coil assembly, wherein the primary coil assembly has a primary yoke element, several primary leg elements, and a primary winding, and the secondary coil assembly has a secondary yoke element, several secondary leg elements, and a secondary winding, wherein the primary yoke element and / or the secondary yoke element each consist of a laminated core, and wherein—viewed in longitudinal section with respect to the axis of rotation—the primary yoke element rests against at least one of the primary leg elements and / or the secondary yoke element rests against at least one of the secondary leg elements along an abutting edge, wherein the abutting edge and / or its longitudinal center axis is inclined with respect to the axis of rotation. The invention further relates to an electric machine.

[0002] For example, the prior art document GB 1 337 815 A, which is considered to define the generic form of a transformer, describes a rotating transformer for a brushless synchronous motor, wherein at least one of the magnetic cores, which carries the rotor windings or the stator windings, is formed from a cylindrical element made of coiled magnetic strips, to the ends of which coaxial disks are attached. The disks and the respective cylindrical elements are bonded with an adhesive or formed with the respective windings in a mold using epoxy resin or another adhesive to create a solid structure. The disks consist of solid material or are laminated in a ring shape.

[0003] Further prior art documents include DE 199 53 583 C1, US 2012 / 0 092 117 A1, GB 989 634 A, US 3 522 520 A and US 3 270 308 A.

[0004] The electric machine serves, for example, to provide torque or to convert mechanical energy into electrical energy. For this purpose, it has a stator and a rotor, which is rotatably mounted relative to the stator. Depending on the type of electric machine, it may be necessary to supply electrical energy to the rotor. This is the case, for example, if the electric machine is designed as an electrically excited synchronous machine. However, other configurations of the electric machine are also possible. An energy transmission device is provided for energy transfer. The energy transmission device has, for example, at least one slip ring and a brush in contact with the slip ring. The slip ring is preferably arranged on the rotor, while the brush is located on the stator.Typically, several slip rings and corresponding brushes are provided.

[0005] The slip ring and brush are now designed in such a way that even when the rotor rotates relative to the stator, a sliding contact between them is maintained permanently, or at least almost permanently, allowing electrical energy to be transferred. However, such a conductive energy transfer device requires intensive maintenance. Furthermore, it is susceptible to contamination and changes in humidity, which can lead to unreliable electrical energy transfer.

[0006] For this reason, the energy transmission device is designed to be contactless, enabling the transfer of electrical energy between the stator and the rotor without physical contact. To this end, a primary coil assembly and a secondary coil assembly are provided. The primary coil assembly can alternatively be referred to as the primary active component, and the secondary coil assembly as the secondary active component. The primary coil assembly is preferably associated with and fixed to the stator of the electric machine. Conversely, the secondary coil assembly is preferably associated with and fixed to the rotor of the electric machine. When the rotor rotates relative to the stator, the secondary coil assembly rotates correspondingly with respect to the primary coil assembly. However, the energy transmission device can also be used in other applications, i.e., independently of the electric machine.

[0007] The object of the invention is to propose a contactless energy transmission device that is easy and inexpensive to manufacture and also has high mechanical strength.

[0008] According to the invention, this is achieved with an energy transfer device having the features of claim 1. It is provided that, viewed in longitudinal section, the butt edge is stepped, and that the primary leg elements and / or the secondary leg elements each consist of a laminated core and have several laminated core parts with a radially extending slot, wherein the laminated core parts are arranged one another such that the radial slots of the several laminated cores are offset from one another in the circumferential direction.

[0009] In principle, it is provided that the primary yoke element and / or the secondary yoke element each consist of a sheet metal package, and that - viewed in longitudinal section with respect to the axis of rotation - the primary yoke element rests on at least one of the primary leg elements and / or the secondary yoke element rests on at least one of the secondary leg elements along a butt joint, wherein the butt joint and / or its longitudinal center axis is inclined with respect to the axis of rotation.

[0010] The primary coil assembly comprises the primary yoke element, the primary leg elements, and the primary winding. The secondary coil assembly is essentially analogous in construction and accordingly comprises the secondary yoke element, the secondary leg elements, and the secondary winding. The primary and secondary coil assemblies are arranged such that when an alternating voltage is applied to the primary coil assembly, a corresponding alternating voltage is induced in the secondary coil assembly. The yoke elements, i.e., the primary yoke element and the secondary yoke element, as well as the leg elements, i.e., the primary leg elements and the secondary leg elements, serve to increase the efficiency of energy transfer between the primary and secondary coil assemblies.

[0011] Preferably, the primary leg elements are provided on both sides of the primary yoke element, so that one primary leg element is arranged on each of the opposite end faces of the primary yoke element. The primary yoke element and the primary leg elements can be arranged in a U-shape relative to each other, viewed in longitudinal section with respect to the axis of rotation, with the primary leg elements being connected to each other via the primary yoke element. Preferably, the primary leg elements are attached to each other exclusively via the primary yoke element and are otherwise spaced apart or separate from each other.

[0012] The primary winding is arranged between the primary leg elements, running around the primary yoke element and thus preferably completely encircling it in the circumferential direction with respect to the axis of rotation. In particular, the primary coil assembly has a plurality of windings, each winding of the primary coil assembly completely encircling the primary yoke element in the circumferential direction. The secondary coil assembly is fundamentally analogous to the primary coil assembly, so reference is made to the preceding descriptions.

[0013] In longitudinal section, each primary leg element has a free end facing away from the primary yoke element. Each secondary leg element also has such a free end, located on the side of the respective secondary leg element facing away from the secondary yoke element. The primary coil assembly and the secondary coil assembly are arranged relative to each other such that the free ends of the primary leg elements and the secondary yoke elements project towards each other. In particular, the free ends of the primary leg elements are aligned with the free ends of the secondary leg elements. Preferably, the arrangement of the primary yoke element and primary leg elements has the same axial dimensions as the arrangement of the secondary yoke element and secondary leg elements. In such an embodiment, these arrangements are preferably positioned in the same axial direction.

[0014] The primary yoke element, the secondary yoke element, or both consist of a laminated core, or a laminated core in each case. A laminated core is an arrangement of several sheets or laminations that are bonded together, for example, by welding. The sheets can be electrically insulated from one another. In this way, eddy currents in the primary or secondary yoke element can be at least partially avoided. The primary or secondary yoke element forms an iron core of the primary or secondary coil assembly, or at least a part thereof. The sheets can be made of electrical steel. By implementing the primary and / or secondary yoke element as a laminated core, excellent fatigue strength is achieved in the power transmission device and / or the electric machine.

[0015] Furthermore, to optimize the flow of magnetic flux in the primary and secondary coil assemblies, an inclined butt joint is provided. This butt joint is located between the primary yoke element and at least one of the primary leg elements, and / or between the secondary yoke element and at least one of the secondary leg elements. This means that the primary yoke element rests against the primary leg element along the butt joint, and vice versa. Therefore, the primary yoke element is not integrally formed with the primary leg elements, and / or the secondary yoke element is not integrally formed with the secondary leg elements. Rather, they initially exist as separate elements that must be joined together.

[0016] In general terms, there is a butt joint between the primary yoke element and each of the primary leg elements, as well as between the secondary yoke element and each of the secondary leg elements. At least one of these butt joints, preferably several, but especially all of them, are inclined with respect to the axis of rotation. This means that the butt joint and / or its longitudinal center axis, or an imaginary extension of the butt joint or the longitudinal center axis, forms an angle with the axis of rotation that is greater than 0° and less than 90°. An angle between 30° and 60°, between 35° and 55°, between 40° and 50°, or exactly 45° is particularly advantageous.

[0017] In longitudinal section, the longitudinal center axis of the butt joint is a straight line between a contact point furthest inwards in the radial direction, where the primary yoke element rests against the corresponding primary leg element or the secondary yoke element rests against the corresponding secondary leg element, and a contact point furthest outwards in the radial direction, where the corresponding yoke element rests against the corresponding leg element.

[0018] In a further embodiment of the invention, the primary leg elements and / or the secondary leg elements each consist of a sheet metal stack that abuts the primary yoke element or the secondary yoke element, respectively, along the butt joint. In this respect, not only the primary yoke element or the secondary yoke element consists of a sheet metal stack. Rather, primary leg elements, preferably each also consisting of a sheet metal stack, are assigned to the primary yoke element, which consists of the sheet metal stack. Additionally or alternatively, secondary leg elements, also each consisting of such a sheet metal stack, are assigned to the secondary yoke element, which consists of the sheet metal stack.As already explained, there are butt edges between the primary leg elements and the primary yoke element, and between the secondary leg elements and the secondary yoke element, at which a primary leg element or secondary leg element abuts the primary yoke element or the secondary yoke element, respectively.

[0019] In a preferred embodiment of the invention, the lamination stack of the primary yoke element and / or the secondary yoke element may be composed of several lamination stack parts, each of which abuts one of several lamination stack parts of the lamination stack of one of the primary leg elements or the secondary leg elements, respectively. The lamination stack parts may each comprise exactly one sheet or several sheets. If the lamination stack part consists of several sheets, it may also be referred to as a lamination stack. The several lamination stack parts that comprise the lamination stack preferably have different dimensions, particularly in longitudinal section with respect to the axis of rotation. In particular, lamination stack parts that are directly adjacent to one another have different dimensions, for example, in the axial direction.Due to the different dimensions of the multiple sheet metal package parts, the inclination of the butt joint can be achieved.

[0020] The individual sheets of the lamination stack can be arranged directly adjacent to each other in the radial direction in the case of the primary yoke element and / or the secondary yoke element. The sheets have their largest dimensions in the axial and circumferential directions, while their thickness in the radial direction is smaller than their dimensions in the axial and circumferential directions. In the case of the primary leg elements and / or the secondary leg elements, the lamination stack can have sheets that are arranged adjacent to each other in the axial direction. Their dimensions in the axial direction are smaller than their dimensions in the circumferential and radial directions.

[0021] The invention provides that, viewed in longitudinal section, the butt joint edge is stepped. A straight butt joint edge is achieved, for example, by forming a chamfer on the primary or secondary yoke element and on the primary or secondary leg element that abuts the primary or secondary leg element along the butt joint edge. In such a configuration, the butt joint edge coincides continuously with a straight line or its longitudinal center axis. According to the invention, the butt joint edge is stepped, i.e., it has a discrete profile. The step is preferably uniform, so that the longitudinal center axis of the stepped butt joint edge is straight or coincides with a straight line.As explained at the outset, the longitudinal center axis of the butt joint, viewed in longitudinal section, preferably corresponds to an imaginary line connecting the innermost contact point in the radial direction with the outermost contact point in the radial direction. The longitudinal center axis can, in principle, have any desired path between these points, but is preferably straight, which is achieved in particular by the uniform stepping of the butt joint.

[0022] In a preferred embodiment of the invention, the primary yoke element and / or the secondary yoke element are curved in the circumferential direction, in particular having a constant radius in the circumferential direction with respect to the axis of rotation. It is especially preferred that the primary yoke element and / or the secondary yoke element completely or at least largely encompass the axis of rotation in the circumferential direction, for example, at least 75%, at least 80%, at least 85%, at least 90%, or at least 95%. The curvature of the primary yoke element and / or the secondary yoke element in the circumferential direction can, in principle, be of any desired shape. Preferably, however, it is constant in the circumferential direction, so that the constant radius is achieved.

[0023] Typically, the primary yoke element associated with the stator is positioned further outwards in the radial direction than the secondary yoke element associated with the rotor. Accordingly, the primary yoke element preferably has a larger radius than the secondary yoke element. Alternatively, a reverse embodiment is of course also possible, in which the primary yoke element is positioned radially inwards and the secondary yoke element radially outwards.

[0024] In a further preferred embodiment of the invention, the primary leg elements and / or the secondary leg elements are annular in shape. The primary leg elements are arranged axially spaced apart from one another, particularly on opposite sides of the primary yoke element. The same applies to the secondary leg elements and their arrangement relative to the secondary yoke element. For example, the primary leg elements are flush with the primary yoke element on one side. This can be provided additionally or alternatively for the secondary leg elements relative to the secondary yoke element. The primary leg elements and / or the secondary leg elements are preferably annular in shape, i.e., they have a central recess when viewed in cross-section with respect to the axis of rotation.

[0025] The invention provides that the primary leg elements and / or the secondary leg elements have at least one radially extending slot. The radial slot is understood to be a radially extending slot that completely extends through at least one of the primary leg elements and / or the secondary leg elements in the radial direction. Additionally, the radial slot may extend completely through this at least one leg element in the axial direction as well. At the position of the radial slot, the respective leg element is thus interrupted in the circumferential direction.

[0026] Additionally, at least one of the primary leg elements and / or the secondary leg elements can have a comb structure. This is formed on the side of the primary leg elements facing away from the primary yoke element, or on the side of the secondary leg elements facing away from the secondary yoke element. The comb structure has a plurality of circumferentially spaced slots, which preferably extend completely through the respective leg element in the axial direction. The slots preferably extend in the radial direction, but only partially penetrate the respective leg element in this direction.

[0027] Circulating currents can be effectively prevented by means of the radial slot and / or the comb structure. The primary leg element and / or the secondary leg element consist of a laminated core comprising several laminated core sections, each of which has such a radial slot. The laminated core sections are arranged such that the radial slots of the several laminated core sections are offset from one another in the circumferential direction, in particular uniformly offset from one another. In this way, a particularly high mechanical strength of the primary leg elements and / or the secondary leg elements is achieved.

[0028] In a further embodiment of the invention, the primary winding and / or the secondary winding comprises a flat ribbon cable. The flat ribbon cable preferably has a width corresponding to the distance between the primary leg elements or the secondary leg elements. However, the width of the flat ribbon cable, relative to the distance between the primary leg elements or the secondary leg elements, is at least 75%, at least 80%, at least 85%, at least 90%, or at least 95%. The flat ribbon cable, for example, has a metal strip extending across its entire width. For example, the metal strip is applied to a carrier material, such as polyester or the like. The flat ribbon cable can also be referred to as a "Flat Flex Cable (FFC)."The flat ribbon cable is a multi-core cable, in which the multiple cores are arranged next to each other or parallel to each other.

[0029] Furthermore, in a preferred embodiment of the invention, a circuit board is arranged at the end face of the secondary coil assembly, the circuit board comprising a rectifier circuit connected to the secondary winding. The secondary coil assembly serves as a support for the circuit board. For example, the circuit board is attached to at least one of the secondary leg elements. The rectifier circuit serves to rectify the electric current supplied by the secondary coil assembly. The rectifier circuit is connected on one side to the secondary winding and on the other side to another electrical circuit, the latter being, for example, an excitation winding of the electric machine. Typically, the rectifier circuit is connected to both ends of the secondary winding.The secondary winding is led out between the secondary leg elements, for example through one of the secondary leg elements. The secondary winding preferably runs through the radial slot and / or a slot of the comb structure.

[0030] In a further embodiment of the invention, components of the rectifier circuit are supported radially against the secondary yoke element of the secondary coil assembly. The circuit board on which the rectifier circuit is arranged is attached to the secondary coil assembly. At least some components of the rectifier circuit are arranged on the side of the circuit board facing the secondary coil assembly. They preferably engage at least partially with the secondary coil assembly so that they can be supported radially against it. The components are supported by the secondary yoke element. In this way, high operational reliability is achieved even at high speeds of the power transmission device and / or the electric machine.

[0031] The invention further relates to an electric machine comprising a stator, a rotor rotatably mounted about an axis of rotation with respect to the stator, and an energy transmission device, in particular an energy transmission device according to the preceding embodiments, wherein the energy transmission device comprises a primary coil assembly associated with the stator and a secondary coil assembly associated with the rotor rotatably mounted about the axis of rotation with respect to the primary coil assembly, and wherein the primary coil assembly comprises a primary yoke element, several primary leg elements, and a primary winding, and the secondary coil assembly comprises a secondary yoke element, several secondary leg elements, and a secondary winding.It is provided that the primary yoke element and / or the secondary yoke element each consist of a sheet metal stack, and that – viewed in longitudinal section with respect to the axis of rotation – the primary yoke element abuts at least one of the primary leg elements and / or the secondary yoke element abuts at least one of the secondary leg elements along a butt joint, wherein the butt joint and / or its longitudinal center axis is inclined with respect to the axis of rotation. Furthermore, it is provided that – viewed in longitudinal section – the butt joint is stepped, and that the primary leg elements and / or the secondary leg elements each consist of a sheet metal stack and have several sheet metal stack parts with a radially extending radial slot, wherein the sheet metal stack parts are arranged one another such that the radial slots of the several sheet metal stack parts are offset from each other in the circumferential direction.

[0032] The advantages of such a design for the energy transmission device and the electric machine have already been mentioned. The energy transmission device and the electric machine can be further developed according to the above descriptions, and reference is made to these in that respect.

[0033] It is possible for the electric machine to be designed as an electrically excited synchronous machine. Such a design has already been mentioned above.

[0034] The invention is explained in more detail below with reference to the exemplary embodiments shown in the drawing, without limiting the invention. The drawing shows: Fig. 1. A longitudinal section view through a section of an electric machine with a power transmission device, and Fig. 2 an exploded view of a section of a secondary coil assembly of the energy transmission device, which is associated with a rotor of the electric machine.

[0035] The Fig. Figure 1 shows a longitudinal section through a portion of an electric machine 1, which has a stator 2 and a rotor 3. The rotor 3 is rotatably mounted about an axis of rotation 4 relative to the stator 2. The rotor 3 is arranged on a shaft 5 of the electric machine 1. The stator 2 and the rotor 3 are only partially shown. In particular, a power transmission device 6 is visible, which has a primary coil assembly 7 associated with the stator 2 and a secondary coil assembly 8 associated with the rotor 3. The primary coil assembly 7 has a primary yoke element 9, several primary leg elements 10 and 11, and a primary winding 12. The secondary coil assembly 8, on the other hand, has a secondary yoke element 13, secondary leg elements 14 and 15, and a secondary winding 16.The primary leg elements 10 and 11 are arranged on both sides of the primary yoke element 9, and the secondary leg elements 14 and 15 are arranged on both sides of the secondary yoke element 13.

[0036] In the longitudinal section shown here, the primary yoke element 9 and the secondary yoke element 13 run parallel to the axis of rotation 4, while the primary leg elements 10 and 11 and the secondary leg elements 14 and 15 are perpendicular to the axis of rotation 4. The primary leg elements 10 and 11 have free ends 17 and 18, and the secondary leg elements 14 and 15 have free ends 19 and 20. The primary coil assembly 7 and the secondary coil assembly 8 are arranged such that the free ends 17 and 19 and the free ends 18 and 20 project towards each other and are aligned with one another. The primary yoke element 9 forms a U-shaped arrangement with the primary leg elements 10 and 11. This is also the case for the secondary yoke element 13 with the secondary leg elements 14 and 15.

[0037] It can be seen that the primary yoke element 9 and the primary leg elements 10 and 11 each consist of a sheet metal stack, each sheet metal stack being composed of a plurality of sheets 21 (shown only by way of example). This is analogous for the secondary yoke element 13 and the secondary leg elements 14 and 15. The primary leg element 10 rests against the primary yoke element 9 along a butt edge 22. A butt edge 23 exists between the primary leg element 11 and the primary yoke element 9. These butt edges 22 and 23, or longitudinal center axes 24 and 25 of the butt edges 22 and 23, are inclined with respect to the axis of rotation 4, thus forming an angle with it in longitudinal section that is greater than 0° and less than 90°. The angle is particularly preferably 45°.

[0038] Similarly, butt edges 26 and 27 with longitudinal center axes 28 and 29 are located between the secondary yoke element 13 and the secondary leg elements 14 and 15. These are also inclined with respect to the axis of rotation 4. In the present case, the inclination of the butt edges 22, 23, 26, and 27 is achieved by forming chamfers on the primary yoke element 9, the primary leg elements 10 and 11, the secondary yoke element 13, and the secondary leg elements 14 and 15. According to the invention, a stepped profile of the butt edges 22, 23, 26, and 27 is provided. At the butt edges 22, 23, 26, and 27, the respective adjacent elements abut each other and are fastened to one another, for example, by a material bond.

[0039] The Fig.Figure 2 shows an exploded view of a section of the electric machine 1, in particular a section of the secondary coil assembly 8. It is evident that the secondary yoke element 13 is composed of several laminated core sections 30, each preferably consisting of several sheets 21. The secondary leg elements 14 and 15 also each have several laminated core sections 30, each of which in turn consists of several sheets 21.

[0040] It is evident that the lamination stack parts 30 have different dimensions. In particular, the lamination stack parts 30 of the secondary yoke element 13 are designed such that they have different dimensions in the axial direction, with the axial dimensions of the lamination stack parts 30 becoming smaller the greater their radial position relative to the axis of rotation 4. In contrast, the lamination stack parts 30 of the secondary leg elements 14 and 15 have radial dimensions that are larger the further the respective lamination stack part 30 is from the secondary yoke element 13 in the axial direction.

[0041] The free ends 19 and 20 facing away from the secondary yoke element 13 are aligned with each other. The dimensions of the lamination stack parts 30 of the secondary yoke element 13 and of the secondary leg elements 14 and 15 are selected such that a stepped profile of the butt edges 26 and 27 results. This allows for comparatively simple manufacturing. Naturally, the primary yoke element 9 and the primary leg elements 10 and 11 can be designed analogously. In this case, reference is made to the preceding descriptions. It is also evident that the secondary winding 16 is a flat ribbon cable and has axial dimensions corresponding to the axial distance between the secondary leg elements 14 and 15. The secondary winding 16 can be covered with an insulating element 31.

[0042] It should be noted again that the energy transfer device 6 described here in connection with the electric machine 1 can also be used separately from it. Accordingly, features relating to the electric machine 1 itself are not mandatory, but optional, for the energy transfer device 6.

Claims

[1] Energy transmission device (6) for contactless transmission of electrical energy, comprising a primary coil assembly (7) and a secondary coil assembly (8) rotatably mounted about an axis of rotation (4) with respect to the primary coil assembly (7), wherein the primary coil assembly (7) comprises a primary yoke element (9), several primary leg elements (10, 11) and a primary winding (12) and the secondary coil assembly (8) comprises a secondary yoke element (13), several secondary leg elements (14, 15) and a secondary winding (16), wherein the primary yoke element (9) and / or the secondary yoke element (13) each consist of a laminated core, and wherein – viewed in longitudinal section with respect to the axis of rotation (4) – the primary yoke element (9) is connected to at least one of the primary leg elements (10, 11) and / or the secondary yoke element (13) is connected to at least one of the secondary leg elements (14, 15) along a butt edge (22, 23, 26, 27) is located, with the buttress edge (22,23,26,27) and / or its longitudinal central axis (24, 25, 28, 29) is inclined with respect to the axis of rotation (4), , characterized by , that - viewed in longitudinal section - the butt edge (22,23,26,27) is stepped, and that the primary leg elements (10,11) and / or the secondary leg elements (14,15) each consist of a sheet metal stack and have several sheet metal stack parts (30) with a radially extending radial slot, wherein the sheet metal stack parts (30) are arranged such that the radial slots of the several sheet metal stack parts (30) are arranged circumferentially offset from each other. [2] Energy transmission device according to claim 1, characterized by , that the primary yoke element (9) and / or the secondary yoke element (13) are curved in the circumferential direction, in particular having a constant radius in the circumferential direction with respect to the axis of rotation (4). [3] Energy transmission device according to any of the preceding claims, characterized by, that the primary leg elements (10,11) and / or the secondary leg elements (14,15) are annular in shape. [4] Energy transmission device according to any of the preceding claims, characterized by that the primary winding (12) and / or the secondary winding (16) has a flat ribbon line or a flat ribbon cable. [5] Energy transmission device according to any of the preceding claims, characterized by , that a circuit board is arranged on the end face of the secondary coil assembly (8) which has a rectifier circuit connected to the secondary winding (16). [6] Energy transmission device according to claim 5, characterized by , that components of the rectifier circuit are supported in a radial direction on the secondary yoke element (9) of the secondary coil assembly (8). [7] Electric machine (1), comprising a stator (2), a rotor (3) rotatably mounted about an axis of rotation (4) with respect to the stator (2), and an energy transmission device (6) according to one or more of the preceding claims, wherein the energy transmission device (6) comprises a primary coil assembly (7) associated with the stator (2) and a secondary coil assembly (8) associated with the rotor (3) rotatably mounted about the axis of rotation (4) with respect to the primary coil assembly (7).

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