Contactless energy transmission device, kit of parts for producing contactless energy transmission device, rotor of electric machine, electric machine and method for installing rotor

Abstract

The invention relates to a contactless energy transmission device (1) for a rotor (2) of an electric machine (3), in particular a separately excited synchronous machine in the drive train of a motor vehicle, comprising a hollow shaft (4) which can be coupled to the rotor (2) of the electric machine (3) in order to transmit torque, the contactless energy transfer device comprises an induction transformer (5) having a primary winding (6) which can be energized and a secondary winding (7) which is arranged at a distance from the primary winding and which can be coupled in an electrically conductive manner to the winding of the rotor (2). The secondary winding (7) of the induction transformer (5) is arranged within and fixed to the hollow shaft (4) for common rotation with the hollow shaft, while the primary winding (6) of the induction transformer (5) is positioned in the hollow shaft (4) in a non-rotatable manner relative to the hollow shaft.

Description

Technical Field

[0001] The invention relates to a contactless energy transmission device for a rotor of an electric machine, in particular a separately excited synchronous machine in the transmission system of a motor vehicle, the contactless energy transmission device comprising: a hollow shaft, which can be coupled to the rotor of the electric machine in a torque-transmitting manner; and an induction transformer, which has an energizable primary winding and a secondary winding spaced apart from the energizable primary winding, which can be electrically conductively coupled to the winding of the rotor. The invention also relates to a kit of parts for producing the contactless energy transmission device, a rotor of an electric machine and an electric machine. Background Art

[0002] Electric machines are increasingly being used to drive motor vehicles in order to create an alternative to internal combustion engines that require fossil fuels. Considerable efforts have been made to improve the suitability of electric drives for everyday use and also to be able to provide users with the driving comfort to which they are accustomed.

[0003] A detailed description of electric drives can be found in an article by Erik Schneider, Frank Fickl, Bernd Cebulski and Jens Liebold published in the German automobile magazine ATZ, Vol. 113, May 2011, pages 360 to 365, entitled: Hochintegrativ und Flexibel Elektrische Antriebseinheit für E-Fahrzeuge (Highly integrated and flexible electric drive unit for electric vehicles). The article describes a drive unit for an axle of a vehicle, which includes an electric motor. Such a drive unit is also referred to as an electric axle or an electrically operable drive train.

[0004] In addition to purely electrically operated drive trains, hybrid drive trains are also known. Such drive trains of hybrid vehicles generally include a combination of an internal combustion engine and an electric motor and enable, for example, a purely electric operating mode in urban areas that simultaneously allows both sufficient range and usability, especially when driving off-road. In addition, in certain operating situations, drive can also be provided simultaneously by the internal combustion engine and the electric motor.

[0005] When developing electric machines intended for electric axles or hybrid modules, there is a need to continuously increase the power density and efficiency of the electric machine while reducing the manufacturing costs, since the cost and weight of the vehicle will be determined to a large extent by the battery size. In this context, it is also known to design the electric machine as a separately excited synchronous machine (SESM). In this case, the electrical output for exciting the rotor windings must be transmitted to the rotor of the separately excited synchronous machine. For traction machines, contact transformers are usually used for this purpose. When these windings are energized, a magnetic field is generated, which combines with the magnetic field of the stator to generate torque. The strength of the rotor field can be adjusted by the intensity of the current supply. In this way, the machine behavior can always be adapted to the respective driving situation in the most efficient way possible.

[0006] A disadvantage of such contact transformers is the mechanical and electrical losses that occur in the contact between the stationary and rotating parts. Other disadvantages are the wear caused by the friction of the parts against each other, the eventual contamination caused by the wear and the relatively large installation space requirement.

[0007] As an alternative to such contact transformers, contactless, inductive transformers are also known, for example. An inductive transformer is usually a rotationally symmetrical transformer with an air gap, which comprises a primary winding and a secondary winding. Usually, an inductive transformer also has a core made of, for example, ferrite. Such a core can be made of one or more parts.

[0008] For example, all parts of the core can be attached to the fixed machine side of the motor, wherein the secondary side winding rotates inside the core. Alternatively, the core parts can be attached to the rotating part of the machine. In this case, the primary core part and the secondary core part are separated by an air gap. Taking into account all tolerances and operating conditions, the air gap must be large enough to ensure that the core parts do not contact each other. For this purpose, the rotary transformer part is usually combined or connected to another component for this purpose to provide a support that can withstand the rotation speed. Examples of such design variations can be found in DE 10 2017 214 776A1 or DE201210201826 A1. Summary of the invention

[0009] The object of the present invention is now to provide a contactless energy transmission device for the rotor of an electric machine, in particular a separately excited synchronous machine within the drive train of a motor vehicle, which contactless energy transmission device has a compact design and a high level of operating reliability even when transmitting high electrical powers.

[0010] This object is achieved by a contactless energy transmission device for the rotor of an electric motor, in particular a separately excited synchronous motor within the transmission system of a motor vehicle, the contactless energy transmission device comprising: a hollow shaft which can be connected to the rotor of the electric motor in a torque-transmitting manner; and an induction transformer having a primary winding which can be energized and a secondary winding which is spaced apart from the primary winding and can be conductively connected to the winding of the rotor, wherein the secondary winding of the induction transformer is arranged inside the hollow shaft and connected to the hollow shaft for rotation therewith, while the primary winding of the induction transformer is positioned in the hollow shaft in a torsionally rigid manner relative to the hollow shaft.

[0011] According to the invention, the inductive transformer is thus integrated into the interior of the hollow shaft. For this purpose, the secondary-side rotating part is inserted into the interior of the hollow shaft. The primary-side upright part is preferably arranged coaxially inside the secondary-side part. Thus, the inductive transformer can be dimensioned to be relatively long in the axial direction and relatively compact in the radial direction. Due to the particularly coaxial arrangement inside the hollow shaft and the design which is relatively long in the axial direction and relatively compact in the radial direction in combination with the radial air gap, a number of advantages can be achieved, which are explained in more detail below.

[0012] Firstly, the separately excited synchronous machine can be designed to be very compact in the axial direction, since no additional installation space needs to be provided for the transformer when using the available installation space in the hollow shaft.

[0013] The rotary transformer part with the secondary winding is supported by a hollow shaft at a fixed speed. The radially compact size of the secondary winding reduces its circumferential speed and therefore reduces the centrifugal forces acting on the secondary winding. This leads to reduced strength requirements for the materials used and components.

[0014] The radial separation between the primary and secondary windings of the induction transformer combined with a low tolerance chain for the rotor bearings enables the air gap between the primary and secondary transformer parts to be minimized, which facilitates reducing the size of the transformer components.

[0015] The relatively long axial direction and relatively compact radial direction dimensions also reduce stray flux components in the induction transformer, which also contributes to reducing the size of the transformer components.

[0016] Furthermore, the induction transformer can be positioned relatively far away from the rotor windings which heat up during operation, so that heating of the transformer by the rotor windings is avoided. The losses of the induction transformer can be further positively influenced if the hollow shaft is additionally cooled in a preferred manner, for example by a cooling fluid inside the hollow shaft.

[0017] Advantageous embodiments of the invention are specified in the dependent claims. The features listed individually in the dependent claims can be combined with one another in a technically meaningful manner and can define further embodiments of the invention. In addition, the features indicated in the claims are described and explained in more detail in the description, wherein further preferred embodiments of the invention are shown.

[0018] According to a likewise preferred embodiment of the invention, if the hollow shaft is made of an electrically conductive material, for example steel, the hollow shaft shields the induction transformer from surrounding components and systems and thus contributes to electromagnetic compatibility (EMC) with surrounding components and systems.

[0019] The hollow shaft can be formed in one piece or in several parts. If the hollow shaft is formed from several parts, these hollow shaft parts can only be joined together after the induction transformer has been combined.

[0020] The induction transformer can be integrated at any axial position inside the hollow shaft. For example, the induction transformer can be integrated in the region of the laminated rotor core or in the region of the rotor winding head.

[0021] According to the invention, it is provided that the secondary winding of the induction transformer is arranged inside the hollow shaft. Very preferably, the secondary coil is completely axially positioned inside the hollow shaft. However, it is also conceivable in principle that the secondary coil is only axially engaged in certain sections of the hollow shaft.

[0022] First, the individual elements of the claimed subject matter of the present invention are explained in accordance with their relevance or mentioned order in the claims, and then particularly preferred embodiments of the subject matter of the present invention are described.

[0023] The rotor is the rotating (rotating) part of the electric machine. The rotor comprises in particular a rotor shaft. The rotor shaft may be hollow, which on the one hand results in a reduced weight and on the other hand allows a lubricant or coolant to be supplied to the rotor body. Preferably, the hollow shaft of the contactless energy transmission device is a rotor shaft of a rotor of an electric machine, which rotor shaft is at least partially hollow.

[0024] In particular, the electric machine can be designed as a rotary machine. In particular, the rotary machine can be configured as a radial flux machine. A radial flux machine is characterized by the fact that the magnetic field lines in the air gap formed between the rotor and the stator extend in the radial direction. The gap between the rotor and the stator is called the air gap. In a radial flux machine, the air gap is a gap that has a circular cross section and whose radial width corresponds to the distance between the rotor body and the stator body.

[0025] In particular, the electric machine is intended for use within the drive train of a hybrid-drive motor vehicle or a fully electric-drive motor vehicle. In particular, the electric machine is dimensioned such that a vehicle speed of more than 50 km / h, preferably more than 80 km / h, and in particular more than 100 km / h can be achieved. The electric motor particularly preferably has an output of more than 50 kW, preferably more than 80 kW, and in particular more than 150 kW. Furthermore, it is preferred that the electric machine provides a speed of more than 8000 rpm, particularly preferably more than 12000 rpm, very particularly preferably more than 1500 rpm.

[0026] For the purposes of this application, a motor vehicle is a land vehicle that moves by machine power without the constraints of railway tracks. The motor vehicle may for example be selected from the group of: a passenger car, a truck, a scooter, a light motor vehicle, a motorcycle, a bus / coach or a tractor.

[0027] The inductive transformer can be arranged inside the hollow shaft. The hollow shaft can be formed in one piece or in several parts. Basically, it is conceivable that the hollow shaft is completely or only partially penetrated by an opening extending along the longitudinal extension of the hollow shaft. For example, it is also conceivable that the hollow shaft has a blind hole, into which the inductive transformer can then be inserted. The hollow shaft is preferably made of a metallic material, in particular steel.

[0028] The inductive transformer is configured such that an electrical output of preferably more than 1 kW, and particularly preferably more than 2 kW, can be transmitted at least temporarily without overloading the transformer electrically or thermally. Most preferably, the inductive transformer is configured to transmit an electrical output between 0.5 kW and 10 kW, preferably between 1 kW and 5 kW, particularly preferably between 2 kW and 4 kW.

[0029] The windings of the transformer are made of an electrically conductive but non-ferromagnetic material, such as copper or aluminum, and are electrically insulated from each other. Preferably, the windings are tangentially aligned around the hollow axis, thereby producing a cylindrical annular winding body with a diameter and a longitudinal extension in the axial direction. Most preferably, the windings are wound around and / or in an iron core made of a ferromagnetic material.

[0030] The winding can be formed from one or more electrical conductors having a circular cross section. It is also conceivable that the cross-sectional shape of the electrical conductors forming the winding is different from a circular shape, in particular a rectangular shape. Particularly preferably, the winding can be formed from insulating copper foils which can be wound around each other in a manner similar to a toilet paper roll.

[0031] According to a further advantageous improvement of the present invention, the number of windings of the primary winding can be greater than the number of windings of the secondary winding, which means that when electrical energy is transferred between the primary winding and the secondary winding, voltage conversion from a relatively high battery voltage to a lower rotor voltage can be achieved.

[0032] In this case, it is further preferred that a voltage between 40 V and 1500 V, preferably between 100 V and 1000 V, most preferably between 300 V and 850 V is applied to the primary winding. Furthermore, in this case, it is preferred that a voltage between 70 V and 500 V is applied to the secondary winding.

[0033] The primary core and / or the secondary core are made of a ferromagnetic material, preferably a ferrite material. The primary core and / or the secondary core can be designed in several parts. The respective core parts are preferably approximately rotationally symmetrical, but can contain elements and recesses for fixing or passing additional components.

[0034] Particularly preferably, the primary core and / or the secondary core each have an annular space shape. Most preferably, the primary core and / or the secondary core have a U-shaped cross-sectional profile with circumferential grooves. Preferably, the grooves of the U-shaped cross-sectional profiles of the primary core and the secondary core are oriented toward each other. It is also particularly preferred that the primary winding enters into the groove of the primary core and / or the secondary winding enters into the groove of the secondary core.

[0035] Preferably, the cylindrical annular secondary winding has a radial outer diameter of less than 500 mm, preferably less than 400 mm, particularly preferably less than 350 mm. Most preferably, the radial outer diameter of the cylindrical annular secondary winding is selected to be between 100 mm and 500 mm, preferably between 150 mm and 400 mm, most preferably between 200 mm and 350 mm. This allows the centrifugal forces acting during operation to be limited to an advantageous magnitude.

[0036] The axial length of the cylindrical annular secondary winding is preferably greater than 50%, preferably greater than 70%, of the radial outer diameter, in particular the diameter of the secondary winding. Such an "elongated" design of the winding has proven to be particularly advantageous for the energy transmission of the inductive transformer. In short, the flat and elongated design of the cylindrical annular secondary winding has proven to be particularly advantageous for the energy transmission characteristics of the inductive transformer.

[0037] It is further highly preferred that the axial length of the cylindrical annular primary winding is between 80% and 120% of the axial length of the cylindrical annular secondary winding, which may also contribute to good energy transfer between the windings.

[0038] Furthermore, it is advantageous if the two axial lengths of the cylindrical ring winding completely overlap axially, whereby the energy transfer between the primary winding and the secondary winding can be further optimized.

[0039] Furthermore, it may be advantageous if the primary core and the secondary core each form a surface adjacent to the air gap, via which the magnetic flux is conducted from one part to the other. Advantageously, the surface of the primary core adjacent to the air gap completely covers the surface of the secondary core adjacent to the air gap and / or the surface of the secondary core adjacent to the air gap completely covers the surface of the primary core adjacent to the air gap, wherein the energy transfer between the primary winding and the secondary winding can be further optimized.

[0040] The rectification electronics may preferably be connected between the secondary winding and the winding of the rotor, such that the secondary winding energizes the winding of the rotor via the interconnected rectification electronics.

[0041] The primary winding may be rotatably mounted and centered relative to the secondary winding, preferably by means of one or more rolling bearings. For this purpose, the rolling elements are arranged to roll between an inner ring and an outer ring of the rolling bearing.

[0042] The inner ring can be made of a metallic material and / or a ceramic material. In principle, it is conceivable to design the inner ring in one part or in multiple parts, in particular in two parts. The inner ring can have an inner ring groove. In particular, the cover gasket, the sealing gasket and / or the seal can be arranged in the inner ring groove, in particular in a force-fitting and / or form-fitting manner. Preferably, the inner ring groove is formed as a circumferential groove in the inner ring.

[0043] The outer ring can be made of a metallic material and / or a ceramic material. In principle, it is conceivable to form the outer ring in one part or in multiple parts, in particular in two parts. The outer ring can have an outer ring groove. In particular, the cover gasket, the sealing gasket and / or the seal can be arranged in the outer ring groove, in particular in a force-fitting and / or form-fitting manner. Preferably, the outer ring groove is formed as a circumferential groove in the outer ring.

[0044] Depending on the type of rolling bearing, the rolling elements have the shape of a sphere or a cylinder. Roller-shaped rolling elements are also called roller bearing elements, and spherical rolling elements are also called bearing balls. Roller-shaped rolling elements can be selected, for example, from the group consisting of symmetrical spherical rollers, asymmetrical spherical rollers, cylindrical rollers, needle rollers and / or tapered rollers.

[0045] Rolling elements can roll inside a rolling bearing, in particular on the inner ring raceway of an inner ring. For this purpose, the surface of the inner ring raceway can advantageously be designed to be correspondingly wear-resistant, for example by means of corresponding surface treatment methods and / or by applying corresponding additional material layers. The inner ring raceway can be designed to be flat or contoured. The contoured design of the inner ring raceway can be used, for example, to guide the rolling elements on the inner ring raceway. On the other hand, the flat form of the inner ring raceway can, for example, allow a certain axial displacement capability of the rolling elements on the inner ring raceway.

[0046] Rolling elements can roll inside the rolling bearing, in particular on the outer ring raceway of the outer ring. For this purpose, the surface of the outer ring raceway can advantageously be designed to be wear-resistant, for example, by means of a corresponding surface treatment method and / or by applying a corresponding additional material layer.

[0047] The outer ring raceway can be designed to be flat or contoured. The contoured design of the outer ring raceway can be used, for example, to guide the rolling elements on the outer ring raceway. On the other hand, the flat form of the outer ring raceway can, for example, allow the rolling elements to have a certain axial displacement capability on the outer ring raceway.

[0048] The rolling elements can be guided and spaced apart in a cage or by rolling element spacers. In principle, it is also conceivable to design a rolling bearing without a cage, which is also called a full-complement rolling bearing. In a full-complement rolling bearing, adjacent rolling elements can touch each other.

[0049] The rolling bearing may have a cage, wherein the cage guides the rolling elements. The cage is designed such that the rolling element balls and / or rolling element rollers are spaced apart from one another, so that, for example, friction and heating of the rolling elements are kept as low as possible. Furthermore, the cage holds the rolling element balls and / or rolling element rollers at a fixed distance from one another during rolling, whereby a uniform load distribution can be achieved. The cage may be formed in one piece or in several parts.

[0050] Rolling bearings can have seals in order to prevent lubricant from escaping from the rolling bearing or to prevent dust or moisture from entering the rolling bearing. For this purpose, the seals used can be provided with one or more sealing lips, which can bear against components of the rolling bearing. These seals are designed so that on the one hand they seal the bearing for as long as possible throughout the service life of the bearing and on the other hand the friction level caused by adjacent seals is not too high.

[0051] The invention also includes a method for assembling a rotor of an electric machine, in particular a separately excited synchronous machine within a drive train of a motor vehicle, the method comprising the following steps:

[0052] providing an inductive transformer having an energizable primary winding and a secondary winding spaced apart from the primary winding and conductively coupled to the winding of the rotor, and

[0053] providing a hollow shaft which can be coupled to the rotor of the electric machine in a torque-transmitting manner, and

[0054] Insert the induction transformer into the hollow shaft.

[0055] Furthermore, according to an equally advantageous embodiment of the invention, it can be provided that the rolling bearing has an inner ring and an outer ring, between which a plurality of rolling elements are accommodated, wherein the inner ring is connected to the hollow shaft for co-rotation, and the outer ring is connected to the lance for co-rotation. This is particularly capable of supporting a modular configuration of the rolling bearing and the hollow shaft. For this purpose, it is then further advantageous that the lance has a first barrel ring section, on the outer side surface of which the primary winding is arranged, and the lance also has a second barrel ring section coaxially arranged with the first barrel ring section, on the inner side surface of which the outer ring of the rolling bearing is arranged, wherein the diameter of the first barrel ring section is smaller than the diameter of the second barrel ring section. Furthermore, the present invention can also be further improved so that the rolling bearing, the hollow shaft, the lance and the induction transformer form a modular structural unit.

[0056] Preferably, a method for assembling a rotor of an electric machine, in particular a rotor of a separately excited synchronous machine within a drive train of a motor vehicle, may comprise the following steps:

[0057] Provide rotor shaft;

[0058] Provide non-contact energy transmission device;

[0059] Connecting the hollow shaft of the contactless energy transmission device to the rotor shaft;

[0060] Connect the secondary winding to the rotor winding.

[0061] The contactless energy transfer device may have rectification electronics connected to the secondary winding.

[0062] In a likewise preferred embodiment variant of the invention, it can also be provided that the contactless energy transmission device has rectifying electronics which are also arranged inside the hollow shaft and are connected to the hollow shaft for co-rotation therewith.

[0063] According to a further preferred development of the invention, it can also be provided that the rectifying electronic device has a circuit board on which the electronic components are arranged, wherein the circuit board has a substantially disk-shaped or circular disk-shaped or cylindrical ring-shaped contour.

[0064] In principle, it is also conceivable that the circuit board is not completely closed on its periphery or is composed of several sections. Therefore, it is also preferred that the contour of the circuit board is in the shape of a disk segment, a circular disk segment or a cylinder ring segment.

[0065] In addition, according to an equally advantageous embodiment of the present invention, it can be provided that the circuit board is connected to the hollow shaft in a material-bound, force-matched and / or form-fitting manner for co-rotation. Alternatively, the rectifier electronics can also be accommodated in a housing, the profile of which is roughly in the shape of a disk, a disk segment or a disk, a disk segment, a barrel ring or a barrel ring segment, and the housing is connected to the hollow shaft in a material-bound, force-matched and / or form-fitting manner for co-rotation. The housing can provide additional mechanical protection, chemical protection or electromagnetic protection for the rectifier electronics. The housing can be made, for example, of plastic or metal material. The housing can be designed as a single part or multiple parts.

[0066] The rectifying electronics can also be encapsulated in a non-conductive material.

[0067] Furthermore, the invention can be further developed such that a cooling fluid can flow through the hollow shaft so that when the contactless energy transmission device is in operation, the heat generated by the rectifying electronics can be dissipated by means of the cooling fluid, which is particularly advantageous for low-loss operation of the induction transformer.

[0068] The invention can also be implemented as a kit of parts for producing a contactless energy transmission device for a rotor of an electric machine, in particular a separately excited synchronous machine within the drive train of a motor vehicle. The kit of parts then comprises in particular:

[0069] an inductive transformer having a primary winding which can be energized and a secondary winding which is spaced apart from the primary winding and is conductively coupled to the winding of the rotor,

[0070] a hollow shaft which can be coupled to the rotor of the electric machine in a torque-transmitting manner,

[0071] • Rectification electronics which may be connected to the secondary winding which may be positioned inside the hollow shaft and which may be connected to the hollow shaft for common rotation therewith.

[0072] This allows to obtain the components required for producing the energy transmission device in a particularly convenient manner. The parts kit can be, for example, a packaging unit. In addition, the parts kit can be designed as a combination of separate storage containers for storing the individual components of the parts kit or corresponding component groups.

[0073] The invention may also include a method for assembling a rotor of an electric machine, in particular a separately excited synchronous machine within a drive train of a motor vehicle. The assembly process then comprises, for example, the following steps:

[0074] providing a hollow shaft which can be coupled to the rotor of the electric machine in a torque-transmitting manner, and

[0075] providing an inductive transformer having an energizable primary winding and a secondary winding spaced apart from the primary winding and conductively coupled to the winding of the rotor, and

[0076] Provide rectification electronics which can be connected to the secondary winding,

[0077] inserting the rectifying electronics into the hollow shaft so that the rectifying electronics are connected to the hollow shaft for common rotation,

[0078] • Connect the rectification electronics to the secondary winding of the induction transformer.

[0079] According to an advantageous embodiment of the invention, it can be provided that the primary winding and the secondary winding of the induction transformer are arranged coaxially with respect to one another inside the hollow shaft. This embodiment has the advantage that it enables particularly efficient transmission of electrical energy.

[0080] According to another further preferred development of the present invention, it can also be provided that the primary winding is arranged on a lance extending axially into the interior of the hollow shaft. The lance can be designed in particular as a hollow cylindrical shaft.

[0081] Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the lance has at least one cooling channel through which a cooling fluid can flow. The advantageous effect of this embodiment is based on the fact that it enables particularly good cooling of the primary winding.

[0082] According to another particularly preferred embodiment of the invention, it can be provided that the contactless energy transmission device has rectifying electronics which are also arranged inside the hollow shaft and connected to the hollow shaft for co-rotation with the hollow shaft. In principle, the rectifying electronics can be placed anywhere in or on the rotor. However, it is preferred that the rectifying electronics are also positioned inside the hollow shaft, since the conditions here are also more favorable for the rectifying electronics in terms of speed stability and thermal conditions.

[0083] Furthermore, the invention can be further developed in that the lance is mounted relative to the hollow shaft by means of a rolling bearing in the hollow shaft. This embodiment has the advantage that it allows a particularly tight tolerance and thus smaller annular gap to be formed between the primary coil and the secondary coil.

[0084] The object of the invention is also achieved by a kit of parts for producing a contactless energy transmission device for a rotor of an electric machine, in particular a separately excited synchronous machine within the drive train of a motor vehicle, the kit of parts comprising: an induction transformer having a primary winding which can be energized and a secondary winding which is spaced apart from the primary winding and can be electrically conductively coupled to the winding of the rotor,

[0085] A hollow shaft, which can be coupled to the rotor of the motor in a torque-transmitting manner, and the secondary winding of the induction transformer is arranged inside the hollow shaft and connected to the hollow shaft for rotation together with the hollow shaft; and a lance, which can be axially inserted into the interior of the hollow shaft, and the primary winding of the induction transformer is arranged on the lance.

[0086] The resulting advantage is in particular that the components of the contactless energy transmission device to be assembled can be provided in a particularly convenient manner. The parts kit can be, for example, a packaging unit. In addition, the parts kit can be designed as a combination of separate storage containers for storing individual components of the parts kit or corresponding component groups.

[0087] According to a further preferred embodiment of the subject matter of the invention, a rotor of an electric machine, in particular a separately excited synchronous machine within a drive train of a motor vehicle, can be provided, which comprises a contactless energy transmission device according to one of claims 1 to 7 .

[0088] Finally, the object of the invention is also achieved by an electric machine, in particular a separately excited synchronous machine within a drive train of a motor vehicle, comprising a rotor according to claim 8 . BRIEF DESCRIPTION OF THE DRAWINGS

[0089] The invention is explained in more detail below with reference to the accompanying drawings without limiting the general concept of the invention.

[0090] In the attached picture:

[0091] Figure 1 An electric machine with contactless energy transmission is shown in a schematic axial section,

[0092] Figure 2 A detailed view of a contactless energy transmission device is shown in axial section,

[0093] Figure 3 A kit of parts for producing a contactless energy transmission device for use in a rotor of an electric motor is shown,

[0094] Figure 4 A motor vehicle having an electric machine is shown in a block diagram,

[0095] Figure 5 An inductive transformer is shown in a perspective partial cross-sectional view,

[0096] Figure 6 A first embodiment of the arrangement of rectifying electronics in a hollow shaft is shown in axial section,

[0097] Figure 7 A second embodiment of the arrangement of rectifying electronics in a hollow shaft is shown in axial section,

[0098] Figure 8 A third embodiment of the arrangement of rectifying electronics in a hollow shaft is shown in axial section,

[0099] Fig. 9 A fourth embodiment of the arrangement of rectifying electronics in a hollow shaft is shown in an axial cross-section,

[0100] Fig.10 A fifth embodiment of the arrangement of rectifying electronics in a hollow shaft is shown in axial section,

[0101] Fig.11 A sixth embodiment of the arrangement of rectifying electronics in a hollow shaft is shown in axial section,

[0102] Fig.12 A detailed view of the contactless energy transmission inside a rolling bearing is shown in an axial section.

[0103] Fig.13 A kit of parts for producing a contactless energy transmission device for a rotor of an electric machine is shown. DETAILED DESCRIPTION

[0104] Figure 1 A contactless energy transmission device 1 for a rotor 2 of an electric motor 3 is shown. Figure 1 In the embodiment shown in FIG. 1 , the electric machine 3 is configured as a separately excited synchronous machine for a drive train 23 of a motor vehicle 24 , also as Figure 4 This is outlined by way of example.

[0105] The rotor 2, which is rotatably mounted in a cylindrical annular stator 22, has a hollow shaft 4, which is connected in a torque-transmitting manner to the rotor 2 of the electric machine 3. The rotor 2 also includes a laminated rotor stack 18, which is connected to the hollow shaft 4 for common rotation. The hollow shaft 4 thus forms the rotor shaft of the rotor 2.

[0106] An inductive transformer 5 is provided for energizing the rotor 2 , the inductive transformer 5 having a primary winding 6 which can be energized and a secondary winding 7 which is spaced apart from the primary winding and is electrically conductively connected to the winding of the rotor 2 .

[0107] As from Figure 1 It can be clearly seen that the secondary winding 7 of the induction transformer 5 is arranged inside the hollow shaft 4 and is connected to the hollow shaft for rotation therewith, while the primary winding 6 of the induction transformer 5 is positioned in the hollow shaft in a torsionally rigid manner relative to the hollow shaft 4 so that the secondary winding 7 rotates around the primary winding 6. The primary winding 6 and the secondary winding 7 of the induction transformer 5 are arranged coaxially with each other inside the hollow shaft 4. The primary winding 6 is arranged on a lance 8 extending axially into the interior of the hollow shaft 4.

[0108] from Figure 2 It can be clearly seen that the lance 8 can be designed in the shape of a cartridge ring and then has an axially extending cooling channel 10 through which a cooling fluid 9 can flow. This ensures that the heat generated at the primary winding 6 can be effectively dissipated. Figure 2 In the embodiment of the hollow shaft 4 shown in FIG. 4 , the hollow shaft is designed in two parts and comprises a first hollow cylindrical shaft section 4 a and a second hollow cylindrical shaft section 4 b , which are connected to one another for common rotation.

[0109] exist Figure 2 In the embodiment shown in the figure, the contactless energy transmission device 1 also has a rectifying electronic device 11, which can also be arranged inside the hollow shaft 4 and connected to the hollow shaft for rotation therewith. In principle, it is also conceivable to provide a seal between the hollow shaft 4 and the lance 8 in order to protect the induction transformer 5 from the ingress of dust and / or cooling fluid, which is not shown in the figure, however.

[0110] The laminated rotor core 18 of the rotor 2 is connected to the radially outer side surface of the hollow shaft 4 for common rotation. Thus, the rotor winding head 19 extends from the distal end surface of the laminated rotor core 18 in the axial direction.

[0111] Figure 2 It is also shown that the hollow cylindrical lance 8 can be mounted relative to the hollow shaft 4 by means of a rolling bearing 12 arranged in the hollow shaft 4 .

[0112] exist Figure 3In the figure, a kit of parts 21 for producing a contactless energy transmission device 1 for a rotor 2 of an electric machine 3, in particular a separately excited synchronous machine within the drive train of a motor vehicle, is shown. For example, the kit of parts 21 can be used to convert or equip the electric machine 3 from a contact power supply of the rotor 2 to a contactless power supply and to provide corresponding device components for this purpose.

[0113] The parts kit 21 comprises: an inductive transformer 5 having a primary winding 6 to which electricity can be supplied and a secondary winding 7 which is spaced apart from the primary winding and which can be electrically conductively coupled to the winding of the rotor 2; and a hollow shaft 4 which can be coupled to the rotor 2 of the electric motor 3 in a torque-transmitting manner. In doing so, the secondary winding 7 of the inductive transformer 5 is arranged inside the hollow shaft 4 and is connected to the hollow shaft for co-rotation with the hollow shaft. The parts kit 21 also comprises a lance 8 which can be axially inserted into the interior of the hollow shaft 4, on which the primary winding 6 of the inductive transformer 5 is arranged. This means, for example, that an existing hollow shaft can be replaced and replaced by the hollow shaft of the parts kit 21. Subsequently, the cylindrical ring-shaped lance 8 can then be inserted into the hollow shaft 4, wherein the primary winding 6 and the secondary winding 7 are then coaxially aligned with each other, as Figure 2 The assembled state of the lance 8 is shown in FIG. The rolling bearing 12 in the parts kit 21 is provided as an option for mounting the cylindrical ring lance 8 .

[0114] Figure 5 A detailed view of an induction transformer 5 is shown. A primary core 13 and a secondary core 14 can be seen, each of which has a toroidal spatial shape. Both the primary core 13 and the secondary core 14 have a U-shaped cross-sectional profile with circumferential grooves, wherein the grooves of the U-shaped cross-sectional profiles of the primary core 13 and the secondary core 14 are oriented toward each other.

[0115] The primary winding 6 is inserted into a groove of the primary core 13, and the secondary winding 7 is inserted into a groove of the secondary core 14. The primary core 13 and the secondary core 14 are made of a ferromagnetic material, preferably a ferrite material.

[0116] exist Figure 5 In the embodiment shown in , the number of windings of the primary winding 6 is greater than the number of windings of the secondary winding 7, so that when electrical energy is transferred between the primary winding 6 and the secondary winding 7, voltage conversion from a relatively high battery voltage to a lower rotor voltage can be simultaneously achieved.

[0117] The two axial lengths of the cylindrical ring windings 6 , 7 overlap axially almost completely, which allows an optimal and preferably loss-free energy transfer between the primary winding 6 and the secondary winding 7 .

[0118] Figures 6 to 11 Various possibilities for arranging the rectifying electronics 11 within the hollow shaft 4 are shown.

[0119] exist Figures 6 to 11 In all embodiments of the present invention, the contactless energy transmission device 1 is connected to the secondary winding 7 via rectifying electronics 11. The rectifying electronics 11 are each arranged inside the hollow shaft 4 and connected to the hollow shaft for co-rotation therewith.

[0120] like Figures 6 to 11 As shown in FIG. , the secondary winding 7 of the induction transformer 5 is preferably arranged inside the hollow shaft 4 and connected to the hollow shaft for rotation therewith, while the primary winding 6 of the induction transformer 5 is positioned in the hollow shaft in a torsionally rigid manner relative to the hollow shaft 4, which is however not shown in FIG. Figures 6 to 11 Not shown.

[0121] The rectifying electronics 11 has a printed circuit board 33 on which electronic components 34 are arranged.

[0122] exist Fig.10 In the embodiment of FIG. 4 , the circuit board 33 has a substantially disk-shaped or disk-segment-shaped contour, which extends substantially in the radial direction inside the hollow shaft 4 . Figure 8 A similar design is shown, in which, however, the printed circuit board 33 has a disk-shaped or disk-segment-shaped contour, so that the printed circuit board 33 can be penetrated and / or flowed through in the axial direction.

[0123] Fig. 9 Another possible arrangement of the printed circuit board 33 is shown, wherein the printed circuit board 33 has a cylindrical ring-shaped or cylindrical ring segment-shaped contour and extends within the hollow shaft 4 approximately in the axial direction.

[0124] Figure 6 , Figure 7 , Fig.11 A further embodiment of the rectifying electronics 11 is shown, in which the rectifying electronics 11 is accommodated in a housing 36 which in turn is connected to the hollow shaft 4 for co-rotation in a materially bonded, force-fitting and / or form-fitting manner. Fig.11 In an embodiment variant, the housing 36 has an approximately disk-shaped or disk-segment-shaped contour.

[0125] The housing 36 can also have a disk-shaped or disk-segment profile, as can also be seen in Figure 6 Thus, for example, the lance 8 or the cooling fluid 9 can pass through the housing 36. Figure 6 and Fig.11 In the embodiment, the housing extends substantially in the radial direction like a disk. In principle, the housing 36 can also extend in the axial direction, such as Figure 7In this embodiment, the housing has a cylindrical ring or a cylindrical ring segment-shaped contour.

[0126] If you can also Figures 6 to 11 As can be seen in the figure, the hollow shaft 4 is designed so that a cooling fluid 9 can flow through the hollow shaft, so that when the contactless energy transmission device 1 is in operation, the heat generated by the rectifying electronics 11 can be dissipated with the aid of the cooling fluid 9. For this purpose, the hollow shaft 4 also serves as a cooling channel 10, through which the cooling fluid 9 can be conveyed axially.

[0127] Fig.12 An embodiment of the invention is shown in which the hollow shaft 4 is mounted rotatably relative to a torsionally rigid connection structure 25 by means of rolling bearings 12. In the embodiment shown, the connection structure 25 is a lance 8. The secondary winding 7 of the induction transformer 5 is also arranged here inside the hollow shaft 4 and connected to the hollow shaft for rotation therewith, while the primary winding 6 of the induction transformer 5 is positioned in the hollow shaft in a torsionally rigid manner relative to the hollow shaft 4. In the embodiment shown, the primary winding 6 is arranged on the lance 8 extending axially into the interior of the hollow shaft 4.

[0128] The rolling bearing 12 has an inner ring 26 and an outer ring 27 between which a plurality of rolling elements 28 are accommodated, wherein the inner ring 26 is connected for common rotation to the hollow shaft 4 and the outer ring 27 is connected for common rotation to the lance 8 .

[0129] The lance 8 has a hollow cylindrical first barrel ring section 29, the primary winding 6 is arranged on the outer side surface of the first barrel ring section, and the lance 8 also has a second barrel ring section 30 arranged coaxially with the first barrel ring section 29, and the outer ring 27 of the rolling bearing 12 is arranged on the inner side surface of the second barrel ring section, wherein the diameter of the first barrel ring section 29 is smaller than the diameter of the second barrel ring section 30. The rolling bearing 12, the hollow shaft 4, the lance 8 and the induction transformer 5 form a modular structural unit 31.

[0130] even though Fig.12 Not shown in the figure, the contactless energy transmission device 1 can also have rectifying electronics 11 which are also arranged inside the hollow shaft 4 and connected to the hollow shaft for co-rotation therewith.

[0131] Fig.13Another possible kit of parts 21 for producing a contactless energy transmission device 1 for a rotor 2 of an electric machine 3 is shown. The kit of parts comprises an inductive transformer 5 having a primary winding 6 to which current can be supplied and a secondary winding 7 which is spaced apart from the primary winding and can be electrically conductively coupled to the winding of the rotor 2, and a hollow shaft 4 which can be coupled in a torque-transmitting manner to the rotor 2 of the electric machine 3. Furthermore, the kit of parts 21 has rectifying electronics 11 which can be connected to the secondary winding 7 which can be positioned inside the hollow shaft 4 and can be connected to the hollow shaft for co-rotation therewith.

[0132] For example, you can use Fig.13 The following method for assembling the rotor 2 of the electric machine 3 is performed using a kit of parts 21 known from the prior art. First, a hollow shaft 4 is provided, which can be coupled to the rotor 2 of the electric machine 3 in a torque-transmitting manner, and an inductive transformer 5 is provided, which has an energizable primary winding 6 and a secondary winding 7, which is spaced apart from the primary winding and can be electrically conductively coupled to the winding of the rotor 2. Rectification electronics 11, which can be coupled to the secondary winding 7, are also provided.

[0133] Then, the rectifying electronics 11 are inserted into the hollow shaft 4 so that they are connected to the hollow shaft 4 for common rotation. Finally, the rectifying electronics 11 can then be connected to the secondary winding 7 of the inductive transformer 5 .

[0134] The present invention is not limited to the embodiments shown in the drawings. Therefore, the above description should not be regarded as limiting, but should be regarded as illustrative. The attached claims should be understood to mean that the stated features exist in at least one embodiment of the present invention. This does not exclude the existence of other features. Where the claims and the above description define a "first" feature and a "second" feature, such naming is used to distinguish between two features of the same type without defining the order of precedence.

[0135] Reference numerals list

[0136] 1 Energy transmission device

[0137] 2 Rotors

[0138] 3 Motor

[0139] 4 Hollow shaft

[0140] 5 Transformer

[0141] 6 Primary Winding

[0142] 7 Secondary Winding

[0143] 8 Spear

[0144] 9 Cooling fluid

[0145] 10 Cooling channels

[0146] 11. Rectifier Electronic Devices

[0147] 12 Rolling bearings

[0148] 13 Primary core

[0149] 14 Secondary core

[0150] 15 Star Hat

[0151] 16 Rotor cover

[0152] 17 Shell structure

[0153] 18 Laminated rotor core

[0154] 19 Rotor winding head

[0155] 20 Rolling bearings

[0156] 21 Parts Kit

[0157] 22 Stator

[0158] 23 Powertrain

[0159] 24 Motor Vehicles

[0160] 25 Connection structure

[0161] 26 Inner Ring

[0162] 27 Outer Ring

[0163] 28 Rolling elements

[0164] 29 barrel ring section

[0165] 30 barrel ring section

[0166] 31 units

[0167] 32 Rotor shaft

[0168] 33 Circuit Board

[0169] 34 Electronic components

[0170] 35 Profile

[0171] 36 Housing

Claims

1. A contactless energy transmission device (1), the contactless energy transmission device being used for a rotor (2) of an electric motor (3), the electric motor being in particular a separately excited synchronous motor in a transmission system of a motor vehicle, the contactless energy transmission device comprising: a hollow shaft (4) which can be coupled to the rotor (2) of the electric motor (3) in a torque-transmitting manner, and an inductive transformer (5) having a primary winding (6) which can be energized and a secondary winding (7) which is spaced apart from the primary winding and can be electrically conductively connected to the winding of the rotor (2), It is characterized in that The secondary winding (7) of the induction transformer (5) is arranged inside the hollow shaft (4) and connected to the hollow shaft for rotation therewith, while the primary winding (6) of the induction transformer (5) is positioned in the hollow shaft in a torsionally rigid manner relative to the hollow shaft (4).

2. The contactless energy transmission device (1) according to claim 1, It is characterized in that The primary winding (6) and the secondary winding (7) of the induction transformer (5) are arranged coaxially with each other inside the hollow shaft (4).

3. The contactless energy transmission device (1) according to claim 1 or 2, It is characterized in that The primary winding (6) is arranged on a lance (8) extending axially into the interior of the hollow shaft (4).

4. The contactless energy transmission device (1) according to claim 3, It is characterized in that The lance (8) has at least one cooling channel (10) through which a cooling fluid (9) can flow.

5. The contactless energy transmission device (1) according to one of the preceding claims, It is characterized in that The contactless energy transmission device (1) has rectifying electronics (11), which are also arranged inside the hollow shaft (4) and connected to the hollow shaft for co-rotation with the hollow shaft.

6. The contactless energy transmission device (1) according to one of the preceding claims 3 to 5, It is characterized in that The lance (8) is mounted relative to the hollow shaft (4) by means of a rolling bearing (12) arranged in the hollow shaft (4).

7. The contactless energy transmission device (1) according to one of the preceding claims, It is characterized in that The axial extension of the secondary winding (7) is greater than 50% of the radial outer diameter of the secondary winding (6), preferably greater than 70% of the radial outer diameter of the secondary winding.

8. A kit of parts for producing a contactless energy transmission device (1) for a rotor (2) of an electric machine (3), in particular a separately excited synchronous machine within a drive train of a motor vehicle, the kit of parts comprising: an inductive transformer (5) having a primary winding (6) which can be energized and a secondary winding (7) which is spaced apart from the primary winding and can be electrically conductively connected to the winding of the rotor (2), a hollow shaft (4) which can be coupled to the rotor (2) of the electric machine (3) in a torque-transmitting manner, and the secondary winding (7) of the inductive transformer (5) is arranged inside the hollow shaft (4) and connected to the hollow shaft for co-rotation with the hollow shaft, and A lance (8) which can be axially inserted into the interior of the hollow shaft (4), the primary winding (6) of the induction transformer (5) being arranged on the lance.

9. A rotor (2) of an electric machine (3), in particular a separately excited synchronous machine within a drive train of a motor vehicle, comprising a contactless energy transmission device (1) according to one of claims 1 to 7.

10. An electric machine (3), in particular a separately excited synchronous machine within a drive train of a motor vehicle, comprising a rotor (2) according to claim 9.

11. A method for assembling a rotor (2) of an electric machine (3), in particular a separately excited synchronous machine in a drive train of a motor vehicle, the method comprising the following steps: providing an inductive transformer (5) having a primary winding (6) which can be energized and a secondary winding (7) which is spaced apart from the primary winding and can be electrically conductively coupled to the winding of the rotor (2), and providing a hollow shaft (4) which can be coupled to the rotor (2) of the electric machine (3) in a torque-transmitting manner, and • Insert the induction transformer (5) into the hollow shaft (4).

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