Rotor, method for manufacturing a rotor, and axial flux machine

Abstract

The present invention relates to a rotor (1) for an electric axial flux machine (2) that can operate as a motor and / or as a generator, the rotor comprising a support (3), a plurality of magnet elements (4) and a plurality of flux conducting elements (5), the plurality of magnet elements being arranged against, on or in the support (3) and extending radially from the inside outwards, the magnet elements (4) being magnetized in the circumferential direction and arranged individually or in groups in series around the circumference in alternating opposite magnetization directions, the plurality of flux conducting elements conducting magnetic flux and being arranged against, on or in the support (3) and arranged around the circumference between the magnet elements (4). According to the invention, at least one conducting element (5) arranged between two magnet elements (4) is formed by a plurality of individual flux conducting elements (50), the individual flux conducting elements (50) being formed such that they conduct magnetic flux tangentially in the circumferential direction and block magnetic flux in the radial direction.

Description

Field of the Invention

[0001] The invention relates to a rotor for an electric axial flux machine which is capable of operating as a motor and / or as a generator, the rotor comprising a support, a plurality of magnet elements, and a plurality of flux conducting elements, the plurality of magnet elements being arranged against, on, or in the support and extending radially outwards from the inside, wherein the magnet elements are magnetized in the circumferential direction and are arranged in the circumferential direction in alternating opposite magnetization directions, either individually or in groups, one after the other, and the plurality of flux conducting elements conduct magnetic flux and are arranged against, on, or in the support and are arranged circumferentially between the magnet elements. The invention also relates to a method of manufacturing the rotor and an axial flux machine. Background of the Invention

[0002] A rotor for an axial flux machine is known from DE10 2013 218 829A1. In the case of such a rotor, a frame is formed by rotor laminations in which inserts are integrated. The rotor laminations have separate punchings for both the magnets and the inserts.

[0003] In particular, DE 10 2017 204 434 A1, DE 10 2005 053 119 A1, DE 10 2004038884A1, DE 10 2015 208 281 A1, DE 10 2017127 157A1 or WO 2018 / 015293A1 describe other configurations of rotors for axial flux machines or axial flux machines themselves. Summary of the Invention

[0004] The invention is based on the object of providing a rotor for an electric machine, a method of manufacturing the rotor, and an electrical axial flux machine which are improved in terms of the structural design of the rotor and the use of materials with respect to cost. Advantageously, the required installation space should at least be able to be retained or further reduced.

[0005] A rotor for an electric axial flux machine that can operate as a motor and / or as a generator according to the present invention, the rotor comprising a support and a plurality of magnet elements, the plurality of magnet elements being arranged against, on, or in the support and extending radially from the inside outwards, wherein the magnet elements are magnetized in the circumferential direction and are arranged individually or in groups in series around the circumference with alternating opposite magnetization directions. Additionally, the rotor comprises a plurality of flux conducting elements, the plurality of flux conducting elements being arranged against, on, or in the support and being circumferentially arranged between the magnet elements and conducting magnetic flux. According to the present invention, at least one flux conducting element arranged between two magnet elements is formed by a plurality of individual flux conducting elements, wherein the individual flux conducting elements are designed such that they conduct magnetic flux tangentially in the circumferential direction and substantially block magnetic flux in the radial direction. The advantage achieved is that inexpensive materials can be used for the flux conducting elements while maintaining a small installation space. Furthermore, an alternative design for the rotor of an axial flux machine is specifically described, the rotor of which previously needed to be equipped with flux conducting elements made of expensive SMC materials. All flux conducting elements are particularly preferably formed by a plurality of individual flux conducting elements.

[0006] For the purposes of the present invention, tangential conductivity and radial blocking are understood to mean that the individual flux conducting elements are implemented such that their conduction in the circumferential tangential direction is much better than their conduction in the radial direction. In particular, in the context of the present invention, blocking means that the conductivity ratio of the conductivity in the radial direction to the conductivity in the circumferential or tangential direction is between 1:2 and 1:100, particularly preferably between 1:50 and 1:100. These ratios depend to a large extent on the absolute operating point of the electric machine or the operating point of the flux conducting elements. In the case of strong magnetization, a ratio close to 1:100 will be used, while in the case of weak magnetization, a ratio close to 1:2 will be used.

[0007] In the different alternatives of "against the support", "on the support", or "in the support" mentioned above, the following statements are exemplary:

[0008] · "against the support": The support is formed, for example, by an inner hub body, wherein the magnets and the flux conducting elements are radially fastened, for example, by means of a ring (referred to as a cylindrical ring), to the outer side of the hub body and / or are radially held on the hub body.

[0009] · "on the support": The support has a disk-shaped region or a radially protruding strut or other protruding support element on which the magnetically active components are attached (for example, by gluing).

[0010] · "in the support member": The support member and the magnetically conductive element are arranged according to the described exemplary embodiment.

[0011] The axial flux type machine according to the present invention is characterized in that the magnetic flux generated in the air gap between the rotor and the stator extends in an axial direction substantially parallel to the rotational axis of the electric machine. In other words, the air gap expands in a plane perpendicular to the rotational axis of the rotor.

[0012] In a particularly preferred embodiment of the support member, the support member has an inner ring and an outer ring. The rotor can be rotatably fixed to the shaft via the inner ring, and the outer ring radially delimits the rotor towards the outside. The support member can be designed to have a base portion located between the inner ring and the outer ring. The inner ring and the outer ring are connected to each other via the base portion, and the base portion together with the radially outer ring surface of the inner ring and the radially inner ring surface of the outer ring has a receiving space that opens in the direction of the air gap for receiving the magnet elements and the flux conducting elements of the rotor.

[0013] The support member can also be designed as a hub structure that extends to the inner radius of the magnetic circuit and is designed to be equipped with attached permanent magnets and flux conductors. Then, a cylindrical annular band or another method (gluing, form-fitting) holds the attached permanent magnets and flux conductors in place.

[0014] In another embodiment of the support member, a support member without an outer ring and / or without a base portion is provided (effectively as a central hub portion, where the radially outwardly directed spokes have radially outwardly directed free ends without limiting an outer ring). The magnet elements and the flux conducting elements can be held radially inwards by gluing on the support member. Alternatively or in addition to gluing, the magnet elements and the flux conducting elements can also be mechanically fixed by claw elements, which are then supported by struts located on the inner hub-shaped support body.

[0015] According to an advantageous embodiment of the invention, it can be provided that the magnet element circumferentially arranged between two flux-conducting elements is designed to increase radially outwards in the body volume of the magnet element by increasing the axial and / or circumferential thickness of the magnet element from the inside outwards. In the case of flux-conducting elements made of stacked metal sheets or the like, the magnetic flux in the radial direction is severely limited due to the laminations, and there is hardly any compensation within the laminations between the rings, which become larger radially outwards. Therefore, it is advantageous to adjust the magnetic excitation according to the radial height by varying the dimensions of the magnet element in the radial direction. If the air gap between the stator and the rotor is divided into radially concentric rings (where the concentric rings are formed approximately by individual columns of circumferentially adjacent laminations), the air gap area of each ring increases with increasing radius. To ensure a constant magnetic flux density in the air gaps of the individual concentric rings, the magnetic excitation must increase in the radial direction (as the radius of the ring increases). The advantage of this configuration is that only as much magnetic material is used as is required for the desired homogeneous magnetic field strength within the air gap.

[0016] According to a further preferably alternative improvement of the invention, it can also be provided that the magnet element circumferentially arranged between two flux-conducting elements has a multi-part design and is formed by a plurality of individual magnet elements having different axial thicknesses, wherein this section achieves the advantage of reduced eddy currents within the magnet element. It can also be achieved that the same parts of the smaller magnet elements can be used for different configurations or applications or standardized parts can be used.

[0017] Furthermore, according to an equally advantageous embodiment of the invention, it can be provided that the flux-conducting element is in the form of laminations, in particular made of electrical steel sheets, which in turn means that inexpensive standard materials can be used and represents a cost-effective alternative to SMC materials.

[0018] According to another particularly preferred embodiment of the invention, it can be provided that the flux-conducting element is designed such that the flux-conducting element has an axial thickness greater than or equal to the axial thickness of the circumferentially adjacent magnet element. In this way, the advantages that can be achieved in particular are that specifically only the material required for the desired function needs to be used, and the cost, installation space, and weight can be further optimized.

[0019] Furthermore, the present invention can also be further modified such that a support member having a three-dimensional profile on the bottom side has a support disk on the bottom side, and the three-dimensional profile is designed to adapt to the axial thickness of the magnet element and / or the flux conducting element, so that the magnet element and the flux conducting element or a separate flux conducting element form an air gap over the entire radial extent of its stator-facing side, and the air gap has a constant axial spacing. The advantage of this configuration is that the resulting gradual change in the axial depth dimension of the support member enables savings in the electrical steel sheet material used, which is more expensive than the support member material. Materials having a high electrical resistivity, a high mechanical tensile strength, and a low specific density are preferably used as the support member material. Preferred materials for this purpose can be fiber-reinforced plastics or aluminum.

[0020] In an equally preferred embodiment of the present invention, it can also be provided that the base of the support member on its support disk is flat, so that a magnet element whose axial thickness varies in the radial direction can form an air gap over the entire radial extent of its stator-facing side, and the air gap has a varying axial spacing. This has the advantage of maximizing the distance between the magnet element and the stator without changing the axial length of the rotor. The advantage of maximizing the distance to the stator is that it reduces the eddy currents in the magnet element caused by the stator.

[0021] It can also be advantageous to further improve the present invention such that the support member has an outer support ring extending in the axial direction and an inner support ring extending in the axial direction, wherein the outer support ring has a polygonal cross-sectional shape on its radially inner ring surface and / or the inner support ring has a polygonal cross-sectional shape on its radially outer ring surface. The advantage that can be achieved in this way is that the torque transmission connection between the support member and the magnet element and the flux conducting element incorporated into the support member is formed by a structurally simple device.

[0022] In addition, the object of the present invention is achieved by a method for manufacturing a rotor for an axial flux type machine, the method comprising the following method steps:

[0023] - Providing a support member,

[0024] - Providing a magnet element and introducing the magnet element against, onto, or into the support member, and

[0025] - Introduce the flux conducting element into the receiving space formed between two magnet elements, wherein the flux conducting element arranged between the two magnet elements is formed by a plurality of individual flux conducting elements, and wherein the individual flux conducting elements are designed such that they conduct magnetic flux tangentially in the circumferential direction and block magnetic flux in the radial direction, and wherein the individual flux conducting elements are preferably formed by a plurality of stacked electrical steel sheets and the plurality of stacked electrical steel sheets are arranged to extend in the circumferential direction in their longitudinal extensions.

[0026] Furthermore, the object of the invention is achieved by an axial flux type machine having a rotor designed according to the invention.

[0027] The axial flux type machine is particularly preferably designed to be arranged in an H shape and includes, in addition to two rotors, a stator arranged centrally between the two rotors. Description of the Drawings

[0028] Without limiting the general concept of the invention, the invention will be explained in more detail below with reference to the drawings.

[0029] In the drawings:

[0030] Figure 1 A perspective view shown schematically shows an axial flux type machine according to the prior art, wherein the rotor is arranged between two stators.

[0031] Figure 2 Another axial flux type machine according to the prior art is shown arranged in an H shape in a perspective view shown schematically.

[0032] Figure 3 The rotor according to the first possible embodiment of the invention is shown in three different views. In the top view, the rotor is shown in an axial section passing through the axis of rotation in the region of the flux conducting element. In the middle view, the rotor is shown in a first perspective view. And in the bottom view, the rotor is shown in a second perspective view, wherein the parts of the support are not equipped with the magnet elements and the flux conducting elements shown schematically respectively.

[0033] Figure 4 The rotor according to Figure 2 is shown. In the left illustration, the rotor is shown in a perspective view with a partial axial section. And in the right illustration, the rotor is shown in an axial section passing through the axis of rotation in the region of the magnet element.

[0034] Figure 5The rotor in a second possible embodiment according to the present invention is shown in three different views. In the top view, the rotor is shown in an axial section passing through the axis of rotation in the region of the flux conducting element. In the middle view, the rotor is shown in a first perspective view. And in the bottom view, the rotor is shown in a second perspective view. Wherein, the parts of the support are not equipped with magnet elements and flux conducting elements respectively shown in schematic representation, and

[0035] Figure 6 shows a rotor according to Figure 5 In the top illustration, the rotor is shown in a perspective view with a partial axial section. And in the bottom illustration, the rotor is shown in an axial section passing through the axis of rotation in the region of the magnet element. Detailed description of the invention

[0036] Figure 1 An axial flux type machine according to the prior art is shown in a perspective view in schematic representation. In the basic structure of the axial flux type machine, the rotor 1 is arranged between two stators 6. The axial flux type machine 2 includes a rotor 1 which is here schematically shown without its support components but with magnet elements 4 and flux conducting elements 5 following one another alternately around the circumference. In the top illustration, the first stator 6 is shown from the inside in a plan view so that the individual stator coils of the stator 6 can be clearly seen. In each case, two adjacent stator coils are advantageously connected together, and three groups of stator coils each driven with an offset angle of 120 degrees produce a total of six adjacent stator coils. In the top illustration, if the first stator 6 is folded down 180 degrees and remains axially spaced from the rotor 1 while forming a first air gap 7, a uniform and compact axial flux type machine results in an "assembled" state. The bottom illustration shows a plan view of the remaining stator-rotor grouping, where the second stator 6 is arranged below the rotor 1 and is axially spaced by a second air gap 13.

[0037] Figure 2 The axial flux type machine 2 according to the prior art is shown in an H-shaped arrangement in a perspective view in schematic representation. In this case, the rotor 1 is axially arranged on both sides of a centrally arranged stator 6, and the stator has stator coils which are each separated by an air gap 7.

[0038] Figure 3The rotor 1 according to the present invention in a first possible embodiment is shown in three different views. In the top view, the rotor 1 is shown in an axial section passing through the axis of rotation in the region of the flux-conducting element 5. In the middle view, the rotor 1 is shown in a first perspective view, and in the bottom view, the rotor is shown in a second perspective view, wherein in the bottom view, the parts of the support 3 are not equipped with the magnet elements 4 and the flux-conducting elements 5. The rotor 1 includes a support 3 designed in the form of an annular disk, and a plurality of magnet elements 4 arranged in the support 3 and radially extending from the inside to the outside on the inner side of the support 3. The support 3 has an inner ring and an outer ring. The rotor can be rotatably fixed to the shaft via the inner ring, and the outer ring defines the rotor towards the outside in the radial direction. The support 3 forms a base portion between the inner ring and the outer ring. The inner ring and the outer ring are connected to each other via the base portion, and the base portion together with the radially outer ring surface of the inner ring and the radially inner ring surface of the outer ring forms a receiving space that is open in the direction of the air gap for receiving the magnet elements 4 and the flux-conducting elements 5 of the rotor 1.

[0039] The magnet elements 4 are magnetized in the circumferential direction along the direction of the arrow drawn in the magnet elements 4, and are shown separately in the exemplary embodiment. Each radial row of the magnet elements themselves is arranged in the circumferential direction with alternating opposite magnetization directions. In addition, a plurality of flux-conducting elements 5 that are circumferentially arranged between the magnet elements 4 and conduct magnetic flux are arranged in the support 3, wherein each flux-conducting element 5 is formed by a plurality of individual flux-conducting elements 50. Each flux-conducting element 50 of the flux-conducting element 5 arranged between two magnet elements 4 is designed as an individual electrical steel sheet having different sizes. The individual sheets are stacked in the radial direction with one behind the other to form a block.

[0040] The magnet elements 4 arranged circumferentially between two flux-conducting elements 5 are designed to become larger radially outwards in their body volume, wherein the axial and / or circumferential / tangential thickness of the magnet elements increases from the inside outwards. The drawing also clearly shows that the magnet elements 4 have a multi-part design and are formed by a plurality of individual magnet elements 40 having different axial thicknesses.

[0041] In accordance with Figure 3In an exemplary embodiment, the depth dimensions (dimensions in the axial direction) of both the flux conducting element 5 or the individual flux conducting elements 50 and the magnet element 4 or the individual magnet elements 40 vary according to the height in the radial direction. Thus, seen in cross-section, a stepped shape is formed, where the steps descend radially outwards from the inside. This is shown in the upper axial sectional view for the flux conducting element 5. The middle view shows the stacking direction of the flux conducting element 5 and the arrangement and magnetization direction of the magnet element 4. The individual magnet element 4 and the flux conducting element 5 are hidden in the lower view so that the adapted shape of the support 3 can also be seen. This is approximately dodecagonal at the inner radius, thus defining a receiving space for the magnet element 4 and the flux conducting element 5 in the radial direction as well as at the outer radius, such that the inner radius is adapted to the profile of the form lines of the magnet element 4 and the flux conducting element 5. The rear wall or bottom part of the support 3 is also adapted to the depth dimensions of the magnet element 4 and the flux conducting element 5. The drawing also shows that the flux conducting element 5 is designed such that the flux conducting element has an axial thickness substantially the same as the axial thickness of the individual magnet element 40 circumferentially adjacent to the magnet element 4, such that a uniform uninterrupted surface with the same air gap dimensions passing through the magnet element 4 and the flux conducting element 5 is formed towards the air gap.

[0042] Figure 4 shows a rotor 1 according to Figure 3 In the left illustration, the rotor is shown in a three-dimensional illustration with a partial axial section, and in the right illustration, the rotor is shown in an axial section passing through the axis of rotation in the region of the magnet element 4. In the illustration on the right, the variation in the depth dimension of the magnet element 4 or the different axial thicknesses of the individual magnet elements 40 according to the radial height can be clearly seen.

[0043] Figure 5 The rotor 1 according to the present invention in a second possible embodiment is shown in three different views. In the upper view, the rotor 1 is shown in an axial section passing through the axis of rotation in the region of the flux conducting element 5. The middle view shows the rotor 1 in a first three-dimensional illustration, and the bottom view shows a second three-dimensional illustration, where in the bottom view, the parts of the support 3 are not equipped with the magnet element 4 and the flux conducting element 5. In this embodiment, the base of the support 3 is flat on the support disk of the support, such that the magnet element 4 with an axially varying thickness can form an air gap 7 with a varying axial spacing over the entire radial extent on its side facing the stator 6. Figure 5 An exemplary embodiment is shown, where the variation in the depth of the magnet element 4 in the axial direction is not arranged at the rear side of the rotor 1 but at the side facing the air gap 7. For the rest, the statements made for the first exemplary embodiment apply to the individual components of the second exemplary embodiment.

[0044] The present invention is not limited to the embodiments shown in the drawings. Therefore, the above description should not be considered restrictive, but rather illustrative. The appended claims should be understood to mean that the specified features exist in at least one embodiment of the present invention. This does not exclude the existence of other features. If the patent claims and the above description define a "first" feature and a "second" feature, such designation is used to distinguish between two features of the same type, rather than to limit the order of arrangement.

[0045] Description of Reference Numerals

[0046] 1 Rotor

[0047] 2 Axial Flux Type Machine

[0048] 3 Support

[0049] 4 Magnet Element

[0050] 5 Flux Conducting Element

[0051] 6 Stator

[0052] 7 Air Gap

[0053] 30 Outer Ring of Support

[0054] 31 Inner Ring of Support

[0055] 40 Single Magnet Element

[0056] 50 Separate Flux Conducting Element.

Claims

1. A rotor (1) for an electric axial flux type machine (2) capable of operating as a motor and / or as a generator, the rotor comprising: - a support (3), - a plurality of magnet elements (4) arranged against, on or in the support (3) and extending radially outwards from the inside, wherein the magnet elements (4) are magnetized in the circumferential direction and are arranged individually or in groups in series around the circumference with alternating opposite magnetization directions, - and a plurality of flux conducting elements (5) for conducting magnetic flux, arranged against, on or in the support (3) and circumferentially arranged between the magnet elements (4), characterized in that, at least one flux conducting element (5) circumferentially arranged between two magnet elements (4) is formed by a plurality of individual flux conducting elements (50), wherein the individual flux conducting elements (50) are designed such that they conduct magnetic flux tangentially in the circumferential direction and block magnetic flux in the radial direction; the support (3) is flat on the base side of the support disk of the support such that the magnet elements (4) whose axial thickness varies in the radial direction can form an air gap on their side facing the stator (6) over the entire radial extension, the air gap having a varying axial spacing.

2. The rotor (1) according to claim 1, characterized in that, the magnet elements (4) circumferentially arranged between two flux conducting elements (5) are designed to increase radially outwards in the body volume of the magnet element due to an increase in the axial and / or circumferential tangential thickness of the magnet element from the inside outwards.

3. The rotor (1) according to claim 1 or 2, characterized in that, the magnet elements (4) circumferentially arranged between two flux conducting elements (5) have a multi-part design and are formed by a plurality of individual magnet elements (40) having different axial thicknesses.

4. The rotor (1) according to claim 1, characterized in that, the flux conducting elements (5) are in the form of laminated sheets.

5. The rotor (1) according to claim 1, characterized in that, the flux conducting elements (5) are designed such that they have an axial thickness greater than or equal to the axial thickness of the magnet elements (4) adjacent in the circumferential direction.

6. The rotor (1) according to claim 1, characterized in that, the support (3) has a three-dimensional profile on the support disk on the base side of the support, the three-dimensional profile being designed to accommodate the axial thickness of the magnet elements (4) and / or the flux conducting elements (5) such that the magnet elements (4) and the flux conducting elements (5) or the flux conducting elements (5) alone form an air gap (7) on their side facing the stator (6) over the entire radial extension, the air gap having a constant axial spacing.

7. The rotor (1) according to claim 1, characterized in that, The support member (3) has an outer support ring (30) extending in the axial direction and an inner support ring (31) extending in the axial direction, wherein the outer support ring (30) has a polygonal cross-sectional shape on its radially inner ring surface and / or the inner support ring (31) has a polygonal cross-sectional shape on its radially outer ring surface.

8. A method for manufacturing a rotor (1) designed according to any one of the preceding claims, The method comprising the following method steps: - providing a support member (3), - providing a magnet element (4) and introducing the magnet element (4) against, onto or into the support member (3), the support member (3) being flat on the base side of the support disk of the support member such that the magnet element (4) whose axial thickness varies in the radial direction can form an air gap on its side facing the stator (6) over the entire radial extent, the air gap having a varying axial spacing; and - Introduce the flux conducting element (5) into the receiving space (6) formed between two magnet elements (4), wherein, the flux conducting element (5) arranged between two magnet elements (4) is formed by a plurality of individual flux conducting elements (50), and wherein the individual flux conducting elements (50) are designed such that they conduct magnetic flux tangentially in the circumferential direction and block magnetic flux in the radial direction, wherein the individual flux conducting elements (50) are formed by a plurality of stacked electrical steel sheets and the plurality of stacked electrical steel sheets are arranged to extend in the circumferential direction in their longitudinal extent.

9. An axial flux type machine (2), characterized in that the axial flux type machine (2) has a rotor (1) according to any one of claims 1 to 7 preceding.

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