Contactless current-transmission device with liquid for an electrical drive machine, and electrical drive machine

Abstract

The invention relates to a current-transmission device (1) for an electrical drive machine (10) of a motor vehicle, with a primary part (2) and a secondary part (3) which is substantially sleeve-shaped overall and accommodated rotatably relative to the primary part (2), wherein the primary part (2) is arranged radially within the secondary part (3) and a contact element (4, 6) of the primary part (2) is coupled by means of a liquid (8) with a contact element (5, 7) of the secondary part (3) arranged at a spatial distance from the contact element (4, 6) of the primary part (2), and wherein the contact element (4, 6) of the primary part (2) and / or the contact element (5, 7) of the secondary part (3) are / is of annular design. The invention also relates to an electrical drive machine (10) comprising this current-transmission device (1).

Description

[0001] Contactless power transmission device with liquid for an electric drive machine; as well as electric drive machine

[0002] The invention relates to a power transmission device for an electric drive motor of a motor vehicle, such as a car, truck, bus, or other commercial vehicle, comprising a primary part and a substantially sleeve-shaped secondary part that is rotatably mounted relative to the primary part. The primary part is arranged radially within the secondary part, and a contact element of the primary part is (electrically) coupled by means of a fluid to a contact element of the secondary part that is spatially spaced from the contact element of the primary part. Furthermore, the invention relates to an electric drive motor having this power transmission device.

[0003] Generic power transmission devices are already well known in the art. For example, DE 11 2020 003 208 T5 discloses a generic power transmission device with a rotary bearing element mounted in a rotor shaft.

[0004] However, in these prior art designs, it has been found that the power transmission device required to ensure mutual contact between the contact elements over the longest possible operating period is relatively complex to maintain. This is due, among other things, to the fact that the volume of the co-rotating electrically conductive fluid typically decreases over the operating period. At the same time, however, depending on their relative rotational position, the contact elements are relatively far apart, which, however, requires a relatively large volume of fluid. As a result, after a certain period of operation, it is possible that electrical contact between the contact elements may be interrupted, depending on their rotational position and the condition of the electrically conductive fluid.

[0005] It is therefore an object of the present invention to provide a contactless power transmission device which has a high level of transmission reliability over the longest possible period of time, but at the same time is designed to be as spatially compact as possible.

[0006] This is achieved according to a first partial aspect of the invention in that the contact element of the primary part and / or the contact element of the secondary part are / is annular.

[0007] The annular design of at least one of the contact elements significantly reduces the likelihood of interrupted current transmission between the contact elements, as this at least one contact element is always in contact with the fluid, regardless of its rotational position. If both interacting contact elements are designed as rings, transmission reliability is significantly increased even further. At the same time, the ring shape of the contact elements makes them radially compact.

[0008] Further advantageous embodiments of the first partial aspect are claimed in the subclaims and explained in more detail below.

[0009] Accordingly, it is also advantageous if the contact element of the primary part and / or the contact element of the secondary part are / is axially fixed.

[0010] Furthermore, it is advantageous if a radial gap filled with the liquid between the contact element of the primary part and the contact element of the secondary part has a thickness (i.e. radial dimension) that is smaller than a thickness (i.e. radial dimension) of the contact element of the primary part and / or the contact element of the secondary part. A gap thickness of less than 1 mm, more preferably less than 300 μm, particularly preferably less than 200 μm has proven particularly suitable. This realizes a suitable compromise between a required liquid volume and a space-saving arrangement of the contact elements. The structure is thus made even more compact, particularly in its radial extent. For damage-free accommodation of the contact element of the primary part, it is also advantageous if it is radially elastically / resiliently supported.

[0011] It is also advantageous if the contact element of the primary part is supported radially from the inside by means of a wave spring. This ensures the elastic support of the contact element of the primary part in the most space-saving way possible. If the wave spring is used directly to secure the contact element of the primary part (to a base body of the primary part), the design is further simplified.

[0012] For a further optimized application, it is advantageous if the primary part and the secondary part each have several, preferably two, annular contact elements that are coupled in pairs by means of a fluid. Thus, the primary part preferably has a first contact element that interacts with a first contact element of the secondary part with the fluid interposed. The primary part has a second contact element, axially spaced from its first contact element, that interacts with a second contact element of the secondary part with the fluid interposed. The respective contact elements are then further connected to poles or terminals in the usual way.In this regard, it is also advantageous if the contact elements of the primary part are each connected to one of two poles of a power supply, whereas the contact elements of the secondary part are each connected to one of two terminals of a rotor winding / coil winding of the rotor.

[0013] If the primary part is essentially sleeve-shaped / tubular, the power transmission device is even more compact. In this regard, it has also proven advantageous if the primary part is mounted on a shaft section, which further simplifies the mounting of the primary part.

[0014] It has also proven advantageous if the primary part and the secondary part are supported rotatably relative to each other by means of a rolling bearing, with an inner ring of the rolling bearing being arranged on a radially outer side of the secondary part and an outer ring of the rolling bearing being accommodated in a support element connected to the primary part. This results in a compact arrangement of the rolling bearing, which enables the aforementioned support, and also in robust support of the two parts relative to each other.

[0015] For an axially compact design, it has also proven advantageous if the rolling bearing is arranged at least in sections at the same axial height with a first contact element of the primary part and a first contact element of the secondary part.

[0016] According to a further, second partial aspect of the invention, which is detached from the first partial aspect and can thus also be the subject of a separate (partial) application, the invention also relates to a power transmission device for an electric drive motor of a motor vehicle, having a primary part and a secondary part which is essentially sleeve-shaped as a whole and is rotatably received relative to the primary part, wherein the primary part is arranged radially within the secondary part and a contact element of the primary part is coupled by means of a liquid to a contact element of the secondary part which is spatially spaced from the contact element of the primary part, wherein the primary part and the secondary part are rotatably supported relative to one another by means of a rolling bearing,An inner ring of the rolling bearing is arranged on a radially outer side of the secondary part, and an outer ring of the rolling bearing is accommodated in a support element connected to the primary part. Thus, the primary part and secondary part are robustly supported relative to each other with means arranged as space-savingly as possible.

[0017] Further advantageous embodiments of the second partial aspect arise from the partial ideas of the first partial aspect and are listed again below for the sake of completeness:

[0018] Power transmission device according to the second aspect, wherein the contact element of the primary part and / or the contact element of the secondary part are / is annular. Power transmission device according to the second aspect, wherein the rolling bearing is arranged at least in sections at the same axial height as a first contact element of the primary part and a first contact element of the secondary part.

[0019] Power transmission device according to the second partial aspect, wherein the contact element of the primary part and / or the contact element of the secondary part are / is axially fixedly supported.

[0020] Power transmission device according to the second partial aspect, wherein a radial gap filled with the liquid between the contact element of the primary part and the contact element of the secondary part has a thickness that is smaller than a thickness of the contact element of the primary part and / or the contact element of the secondary part.

[0021] Power transmission device according to the second partial aspect, wherein the contact element of the primary part is supported radially elastically / resiliently.

[0022] Power transmission device according to the second partial aspect, wherein the contact element of the primary part is supported radially from the inside by means of a corrugated spring.

[0023] Power transmission device according to the second partial aspect, wherein the primary part and the secondary part each have a plurality of annular contact elements which are coupled in pairs by means of a liquid.

[0024] Power transmission device according to the second partial aspect, wherein the primary part as a whole is essentially sleeve-shaped.

[0025] The invention further relates to an electric drive machine for a motor vehicle, comprising a rotor and a current transmission device according to the invention, connected to a coil winding of the rotor, according to at least one of the previously described embodiments (of the first or second partial aspect). The drive machine is particularly preferably a separately excited synchronous machine. With regard to the aforementioned fluid used according to the invention (both with regard to the first partial aspect and the second partial aspect), it should be noted that it is preferably an electrically conductive fluid. The fluid itself is preferably electrically conductive and / or is mixed with electrically conductive additives, wherein it is then in turn electrically conductive as a liquid in its entirety. In principle, the electrically conductive fluid can be formed as a liquid metal or an ionic liquid or the like.Preferably, however, the electrically conductive liquid is in the form of a conductive oil or conductive grease. Although conductive oils and greases generally have a lower conductivity than, for example, liquid metal, they are less toxic and / or easier to handle. By adjusting the radial gap between the contact elements of the primary and secondary parts, losses in conductivity can be compensated for, thus enabling the technically sensible use of conductive oils and / or conductive greases. In particular, an electrically conductive liquid with an electrical conductivity at 25°C of greater than 10,000 nS / m, in particular greater than 30,000 nS / m, is used, such as oils or greases with conductive additives or other oil-free and / or grease-free liquids. These are particularly suitable for low-resistance applications.

[0026] For lower requirements on the transmission resistance, i.e. for higher transmission resistances, even conventional gear oils can be used due to the appropriate thickness of the radial gap between the contact elements of the primary part and the secondary part.

[0027] In an alternative embodiment, the electrically conductive fluid then has an electrical conductivity at 25°C of less than 500 nS / m, preferably less than 300 nS / m and in particular less than 100 nS / m or less than 50 nS / m. On the other hand, it is preferred that the electrical conductivity is greater than 1 nS / m, preferably greater than 5 nS / m and in particular greater than 10 nS / m. With this electrical conductivity, it is possible to use conventional gear oils, so that specially adapted fluids, in particular those with conductive additives, can be dispensed with. This is made possible by using a reduced annular gap width / thickness of the radial gap between the contact elements of the primary part and the secondary part. Thus, according to further embodiments, it is also possible to use non-conductive oil or non-conductive grease as the fluid.

[0028] The invention will now be explained in more detail below with reference to figures.

[0029] They show:

[0030] Fig. 1 is a longitudinal sectional view of a power transmission device according to the invention according to a preferred embodiment, wherein two contact element pairs of a primary part and a secondary part can be seen in more detail with regard to their design and arrangement,

[0031] Fig. 2 is a perspective view of the power transmission device according to Fig. 1 in a full view,

[0032] Fig. 3 is a cross-sectional view of the current transmission device in the area of ​​a pair of contact elements,

[0033] Fig. 4 a perspective view of the primary part in a full view,

[0034] Fig. 5 is a perspective view of the secondary part cut in the longitudinal direction,

[0035] Fig. 6 is a longitudinal sectional view of the current transmission device according to the invention, further illustrating a rolling bearing supporting the secondary part relative to the primary part,

[0036] Fig. 7 is an exploded view of the power transmission device with rolling bearing, sectioned in the longitudinal direction in Fig. 6,

[0037] Fig. 8 is a schematic longitudinal sectional view of an electric drive machine having the power transmission device of Figs. 1 to 7, and Fig. 9 is a side view of the complete drive machine according to Fig. 8.

[0038] The figures are merely schematic and serve solely to clarify the invention. The same elements are designated by the same reference numerals.

[0039] Based on Figures 8 and 9, a preferred area of ​​application of the current transmission device 1 according to the invention is the use in an electric drive machine 10 of a motor vehicle, which motor vehicle is designed either as a purely electrically or hybrid-powered motor vehicle.

[0040] The power transmission device 1 serves to supply an electrical power / an electrical current to a schematically indicated coil winding 21 of a rotatably mounted rotor 20 of the electric drive machine 10.

[0041] According to Figs. 8 and 9, the power transmission device 1 projects at least partially axially into a rotor shaft 24 of the rotor 20. In particular, a sleeve-shaped / tubular secondary part 3, explained in more detail below, is connected in a rotationally fixed manner to the rotor shaft 24. The electric drive machine 10 typically further comprises a stator 25, which is also entirely annular and is arranged radially outside the rotor 20.

[0042] It should be noted that the directions used herein, axial, radial, and circumferential, are relative to a rotational axis 26 of the rotor 20, which rotational axis 26 corresponds to a longitudinal axis of the power transmission device 1. Consequently, the axial / axial direction is understood to mean a direction along / parallel to the rotational axis 26, the radial / radial direction is understood to mean a direction perpendicular to this rotational axis 26, and the circumferential direction is understood to mean a direction along a circular line concentric with the rotational axis 26.

[0043] In conjunction with Figs. 1 to 5, the actual power transmission device 1 is illustrated in detail with respect to its primary part 2 and its secondary part 3. It can be seen that the primary part 2, arranged radially inside the secondary part 3, is entirely sleeve-shaped / tubular. The primary part 2 has, when viewed together with Figs. 1 and 4, an essentially sleeve-shaped / tubular base body 17, which is formed from a single piece of material. This base body 17 is naturally made of electrically non-conductive / insulating material. Lines 18a, 18b are accommodated / introduced into this base body 17, forming two separate poles. Both lines 18a, 18b are clearly visible in Fig. 4. The lines 18a, 18b protrude from the base body 17 to a side axially facing away from the rotor 20 and are further coupled to a power source during operation of the electric drive machine 10.Each line 18a, 18b has a circular segment-shaped contact region 19a, 19b in the base body 17, which extends in the circumferential direction of the base body. A first line 18a opens into a first contact region 19a, which is arranged in a first axial position of the base body 17 and is accessible / exposed radially outward with respect to the base body 17. A second line 18b has a second contact region 19b, which is arranged at a second axial position of the base body 17, axially spaced from the first contact region 19a, and is also exposed radially outward with respect to the base body 17. In this regard, it should also be noted that the contact regions 19a, 19b do not extend completely in the circumferential direction.

[0044] Furthermore, the primary part 2 has two contact elements 4 and 6, each of which is annular in shape. A first contact element 4 of the primary part 2 is electrically connected to the first contact region 19a. A second contact element 6 of the primary part 2, which is arranged axially spaced from the first contact element 4, is electrically connected to the second contact region 19b. It can be seen in Fig. 4 that the two contact regions 19a, 19b are arranged axially between the contact elements 4, 6 of the primary part 2.

[0045] Each contact element 4, 6 of the primary part 2 has an axially projecting contact nose 27a, 27b, with which it contacts the contact area 19a, 19b / rests thereon. The respective contact element 4, 6 of the primary part 2 thus extends completely in the circumferential direction. Each contact element 4, 6 of the primary part 2 is received radially from the outside on the base body 17. In this regard, when looking at Figs. 1 and 3 together, it is also apparent that the respective contact element 4, 6 of the primary part 2 is supported in the radial direction from the inside by a corrugated spring 9. As a result, the respective contact element 4, 6 of the primary part 2 is arranged / supported to a certain extent elastically / movably in the radial direction relative to the base body 17.

[0046] Furthermore, it can be seen that the contact elements 4, 6 of the primary part 2 are also firmly supported axially. The respective contact element 4, 6 of the primary part 2 is fixed to the base body 17 in the axial direction by means of the wave spring 9.

[0047] The secondary part 3, arranged radially outside the primary part 2, can again be clearly seen when looking at Figs. 1 and 5 together. The secondary part 3 has a sleeve-shaped / tubular base body 28, which accommodates several connections, namely two, forming two connecting lines 29a, 29b. A first connecting line 29a and a second connecting line 29b protrude from the base body 28 toward an axial side facing the rotor 20. The base body 28 is naturally made of electrically non-conductive / insulating material.

[0048] Each connecting line 29a, 29b is electrically connected to a contact element 5, 7 of the secondary part 3. The first connecting line 29a is electrically connected to a first contact element 5 of the secondary part 3, and the second connecting line 29b is electrically connected to a second contact element 7 of the secondary part 3.

[0049] Fig. 5 also shows that the contact elements 5, 7 of the secondary part 3 are essentially ring-shaped as a whole. For easier assembly, it is advantageous if they are slotted at a circumferential location. A metal / sheet metal sleeve 32 is preferably pressed / attached radially from the outside onto the base body 28.

[0050] It is also evident that the two annular contact elements 5, 7 of the secondary part 3 are preferably clamped axially fixed. According to Fig. 1, the first contact element 4 of the primary part 2 is arranged axially at the same height as a first contact element 5 of the secondary part 3 and thus form a matching first contact element pair. The first contact element 5 of the secondary part 3 here has a smaller axial width than the first contact element 4 of the primary part 2. The second contact element 6 of the primary part 2 is arranged axially at the same height as a second contact element 7 of the secondary part 3 and thus form a matching second contact element pair. The second contact element 7 of the secondary part 3 here has a smaller axial width than the second contact element 6 of the primary part 2.

[0051] Furthermore, it should be noted that a radial gap 11 is provided radially between the contact elements 4, 5; 6, 7 of the respective contact element pair, so that the contact elements 4, 5; 6, 7 of the respective contact element pair are arranged radially spaced and contactless with each other.

[0052] During operation, an electrically conductive fluid 8 is filled into the gap 11. In particular, the fluid 8 is preferably filled into a radial gap 23 between the primary part 2 and the secondary part 3, in which the contact elements 4, 5; 6, 7 are also arranged. The gap 23 is sealed on its two axially opposite sides by seals 30a and 30b. The sealing rings 30a, 30b are designed as radial shaft seals.

[0053] It can be seen that the gap 11 between the first contact element 5 of the secondary part 3 and the first contact element 4 of the primary part 2 has the same dimensions as the gap 11 between the second contact element 7 of the secondary part 3 and the second contact element 6 of the primary part 2. Each gap 11 is dimensioned to be as thin as possible. In this regard, it can be seen that each gap 11 has a smaller thickness / height in the radial direction than the respective contact element 4, 6 or 5, 7. The gap 11 is preferably less than 200 μm thick.

[0054] Thus, during operation, when the current is transmitted, the current is transmitted via the lines 18a, 18b and the pairs of contact elements 4, 5 and 6, 7 via the connecting lines 29a, 29b to the coil winding 21 of the rotor 20. Figures 6 and 7 clearly show that the primary part 2 and the secondary part 3 are mounted so as to be rotatable relative to one another via a special bearing arrangement. The primary part 2, which is fixed to the housing / stationary during operation, is connected by its base body 17 to a shaft section 22 or is fixedly held thereon. The shaft section 22 is also connected in a rotationally fixed manner to a support element 16. The support element 16 is pot-shaped as a whole and extends radially outwards from an area connected to the shaft section 22.

[0055] The support element 16 extends radially outward to such an extent that it ultimately terminates in an (axially extending) sleeve region 31. The sleeve region 31 is arranged radially outside the secondary part 3, spaced from the secondary part 3. A rolling bearing 12 is arranged between the sleeve region 31 and a radial outer side of the secondary part 3 or a support sleeve 34 of the secondary part 3. The support sleeve 34 is pressed / placed radially from the outside onto the base body 28 and the sheet metal sleeve 32.

[0056] The rolling bearing 12 is implemented here as a ball bearing. In particular, the rolling bearing 12 is even designed as a sensor bearing. The rolling bearing 12 has an inner ring 13, which is received directly on the radial outer side 15 of the secondary part 3 / is fixed thereto. An outer ring 14 of the rolling bearing 12, arranged radially outside the inner ring 13, is pressed into the sleeve area 31 / is firmly held therein. This ensures reliable radial and axial support of the primary part 2 relative to the secondary part 3 during operation.

[0057] It can be seen that the rolling bearing 12 is arranged in the axial direction at least in sections at the level of the first contact element 4 of the primary part and thus also of the first contact element 5 of the secondary part 3.

[0058] As can be seen again in Figs. 8 and 9, this power transmission device 1, including the bearing assembly, is housed in a housing component 33, which is designed as a flange here. For this purpose, the support element 16 is mounted in the component 33 in a radially fixed and axially movable manner.

[0059] In other words, according to the invention (particularly with regard to the first aspect), a contactless and thus wear-free transformer (current transmission device 1) is implemented, which establishes contact via contact elements 4 to 7. These create a targeted gap 11 between the primary part 2 and the secondary part 3, which is bridged by an electrically conductive liquid 8, whereby the currents can be transmitted reliably.

[0060] The structure of the contactless transformer is as follows: The primary-side, stationary part consists of an insulating sleeve (base body 17), connections (leads 18a, 18b), spring elements (wave spring 9), primary contact elements (first contact element 4 and second contact element 6 of the primary part 2), and electrical connectors (contact areas 19a, 19b). The secondary-side, rotating part consists of a steel sleeve (sheet metal sleeve 32), an insulating sleeve (base body 28), secondary contact elements (first contact element 5 and second contact element 7 of the secondary part 3), and connections (connecting leads 29a, 29b). Seals 30a, 30b and the electrically conductive fluid 8 are added during assembly of the module.

[0061] The function is as follows: The insulating sleeve acts as a support in the primary part 2. Two primary contact elements, representing the positive and negative poles, are spaced apart on this sleeve. These two contact elements are mounted radially elastically and axially fixed by spring elements (e.g., wave springs 9). The two poles are connected to the two terminals via elastic electrical connections. They also have anti-rotation features so that they can compensate for radial tolerances, but are otherwise connected to the support in a rotationally fixed manner.

[0062] The secondary part 3 contains a steel sleeve (sheet metal sleeve 32) that serves as a support, housing the insulating sleeve. Two secondary contact elements, representing the positive and negative poles, are spaced apart within this. These two contact elements are firmly attached to the insulating sleeve, and the tracks run parallel to the primary contact elements. The two poles are connected to the two terminals via electrical connections.

[0063] During assembly of the primary part 2 and the secondary part 3, an electrically conductive liquid 8 is poured in, and the resulting assembly is sealed with two seals 30a, 30b. Thus, the system can be used in wet and dry electric machines / electric drive units 10.

[0064] An advantage of the preferred embodiment is that the two primary contact elements are radially elastically mounted via spring elements, thus compensating for axial misalignments and tolerances between the primary and secondary parts. This ensures that the maximum permissible gap between the primary and secondary contact elements is maintained and limited.

[0065] The design allows for a certain axial offset between the primary and secondary parts. This allows for the axial play that must be provided for in a floating bearing arrangement to be compensated for in this configuration.

[0066] A further advantage of this system is that the contactless operation means there are no mechanical losses and therefore no wear. Compared to contact-based transformers, there is also no abrasion. The electrical losses are also reduced compared to conventional transformer types thanks to the electrically conductive fluid. Due to the reduction in mechanical and electrical losses, no active cooling is required. The electrically conductive fluid ensures that there is always contact between the primary and secondary contact elements. This system therefore has no negative impact on electromagnetic compatibility (EMC). Additional shielding for the transformer is not required. Due to its design, the transformer can be positioned away from the rotor windings, which become hot during operation, thus preventing the rotor windings from heating up the transformer.The design ensures secure electrical separation of the two poles, eliminating the need for encapsulation of the two poles. This reduces the axial installation space. The pole areas can also be separated by an additional seal, so that each pole forms its own contact area. The design also allows for the two poles to be separated. In this case, an assembly with just one pole can be created and installed twice in the electric motor. Sensors or electronics for processing or transmitting sensor signals, e.g., for determining rotor position, torque, or temperature, can be integrated into the assembly. The assembly can be built, tested, advertised, and sold as a standalone product.

[0067] The contactless transformer (particularly with regard to the second aspect) is combined with a bearing (rolling bearing 12) to form a self-contained assembly. The secondary-side, rotating part of the contactless transformer is inserted into the interior of the inner bearing carrier (support sleeve 34). This is firmly connected to the inner ring 13 of the bearing. The primary-side, stationary part is arranged coaxially inside the secondary-side part. The primary-side, stationary part is firmly connected to the outer ring 14 of the bearing.

[0068] The structure of the bearing-transmitter unit is as follows: The bearing unit consists of an outer bearing carrier (carrier element 16), the inner bearing carrier, the bearing, a further carrier element (shaft section 22, e.g. designed as an oil lance) for the primary part of the transmitter and the “conductive liquid transmitter”.

[0069] It works as follows: The bearing is extended by an inner and outer bearing carrier. The outer bearing carrier is attached to the outer ring of the bearing and accommodates the primary-side, stationary part of the transformer. The primary part of the transformer is attached to the outer bearing carrier via a support element (e.g. oil lance, which can also be used for oil feedthrough). The inner ring of the bearing is attached to the inner bearing carrier. The inner bearing carrier forms part of the multi-part rotor shaft and accommodates the secondary-side, rotating part of the transformer. Due to the arrangement inside the inner bearing carrier, the axially long but radially compact dimensions in conjunction with a radial gap in the transformer, and the design as a self-contained assembly, a number of the technical problems mentioned can be solved or reduced: No additional installation space is required.The installation space below the bearing is utilized, creating a compact bearing-transformer unit. The integrated contactless transformer also prevents the mechanical losses of the bearing-transformer unit from increasing. The rotating transformer section is supported at a fixed speed by the inner bearing carrier. The radially compact dimensions further alleviate the requirements regarding speed stability. Weight is reduced, as no additional components are required to accommodate the transformer. The radial separation between the primary and secondary transformer sections, combined with a tight tolerance chain for the rotor bearing, enables the gap in the transformer between the primary and secondary transformer sections to be minimized, which favors a minimization of the transformer components.The transformer is positioned away from the rotor windings, which become hot during operation, thus preventing the transformer from heating up due to the rotor windings. If the inner bearing carrier (rotor shaft) is cooled, e.g., by a fluid inside the rotor shaft, the transformer's losses can be efficiently dissipated. The radial tolerance chain is reduced because the connection is made directly to the bearing, meaning only the bearing clearance has an influence. The axial tolerance chain is reduced because the connection is made directly to the bearing, eliminating the axial clearance that must be provided for with a floating bearing.

[0070] If the inner bearing carrier (support sleeve 34) is made of an electrically conductive material, e.g. steel, it additionally shields the transformer from surrounding components and systems and thus contributes to electromagnetic compatibility (EMC) with surrounding components and systems.

[0071] Sensors or electronics for processing or transmitting sensor signals, e.g., for determining rotor position, torque, or temperature, can also be integrated into the assembly (power transmission device 1 with rolling bearing 12). This unit can be developed, constructed, and tested as a self-contained assembly.

[0072] List of reference symbols

[0073] Power transmission device

[0074] Primary part

[0075] Secondary part first contact element of the primary part first contact element of the secondary part second contact element of the primary part second contact element of the secondary part Liquid

[0076] Wave spring

[0077] drive machine

[0078] gap

[0079] Rolling bearings

[0080] inner ring

[0081] Outer ring

[0082] outside

[0083] Support element

[0084] Base body a first line b second line a first contact area b second contact area

[0085] rotor

[0086] Coil winding

[0087] Wave section

[0088] space

[0089] rotor shaft

[0090] stator

[0091] Rotation axis a first contact nose b second contact nose base body a first connecting lead b second connecting lead a first sealing ring b second sealing ring sleeve area sheet metal sleeve housing component support sleeve

Claims

Patent claims 1. A power transmission device (1) for an electric drive machine (10) of a motor vehicle, comprising a primary part (2) and a secondary part (3) which is substantially sleeve-shaped as a whole and is rotatably received relative to the primary part (2), wherein the primary part (2) is arranged radially inside the secondary part (3) and a contact element (4, 6) of the primary part (2) is coupled by means of a liquid (8) to a contact element (5, 7) of the secondary part (3) which is spatially spaced from the contact element (4, 6) of the primary part (2), characterized in that the contact element (4, 6) of the primary part (2) and / or the contact element (5, 7) of the secondary part (3) are / is annular.

2. Power transmission device (1) according to claim 1, characterized in that the contact element (4, 6) of the primary part (2) and / or the contact element (5, 7) of the secondary part (3) are / are axially fixedly received.

3. Power transmission device (1) according to claim 1 or 2, characterized in that a radial gap (11) filled with the liquid between the contact element (4, 6) of the primary part (2) and the contact element (5, 7) of the secondary part (3) has a thickness which is smaller than a thickness of the contact element (4, 6) of the primary part (2) and / or the contact element (5, 7) of the secondary part (3).

4. Power transmission device (1) according to one of claims 1 to 3, characterized in that the contact element (4, 6) of the primary part (2) is supported radially elastically / resiliently.

5. Power transmission device (1) according to one of claims 1 to 4, characterized in that the contact element (4, 6) of the primary part (2) is supported radially from the inside by means of a corrugated spring (9).

6. Power transmission device (1) according to one of claims 1 to 5, characterized in that the primary part (2) and the secondary part (3) each have a plurality of annular contact elements (4, 5; 6, 7) which are coupled in pairs by means of an electrically conductive liquid (8).

7. Power transmission device (1) according to one of claims 1 to 6, characterized in that the primary part (2) is essentially sleeve-shaped as a whole.

8. Power transmission device (1) according to one of claims 1 to 7, characterized in that the primary part (2) and the secondary part (3) are supported rotatably relative to one another by means of a rolling bearing (12), wherein an inner ring (13) of the rolling bearing (12) is arranged on a radial outer side (15) of the secondary part (3) and an outer ring (14) of the rolling bearing (12) is received in a carrier element (16) connected to the primary part (2).

9. Power transmission device (1) according to claim 8, characterized in that the rolling bearing (12) is arranged at least in sections at the same axial height with a first contact element (4) of the primary part (2) and a first contact element (5) of the secondary part (3).

10. Electric drive machine (10) for a motor vehicle, with a rotor (20) and a current transmission device (1) according to one of claims 1 to 9 connected to a coil winding (21) of the rotor (20).

Images