Magnetic levitation device and electromagnetic rotary drive mechanism

Abstract

To provide a magnetic levitation device with low eddy current losses.SOLUTION: A device of contactless magnetic levitation of a rotor 3, which has a disk-or ring-shaped core 31, includes a stator 2 with a cup-shaped recess, which is arranged at an axial end of the stator 2 and into which the rotor 3 can be inserted. The stator 2 has a plurality of coil cores 25, each of which has a longitudinal leg 26 and a magnetic pole piece 27. Each longitudinal leg 26 extends from a first end 261 in an axial direction A to a second end 262, and a contact surface 271 is arranged at the second end 262. Each magnetic pole piece 27 extends from the contact surface in a radial direction R to an end face 272. The radial direction R is perpendicular to the axial direction A, and the end faces 272 are arranged around the cup-shaped recess. At least one concentrated winding surrounds each longitudinal leg 26. Each magnetic pole piece 27 is made of transverse sheet metal elements 273, and the transverse elements 273 are stacked in the axial direction A.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a magnetic levitation device according to the preamble of the independent patent claim, and to an electromagnetic rotary drive mechanism equipped with such a magnetic levitation device. [Background technology]

[0002] Magnetic bearing devices for non-contact magnetic bearing of a rotor have the advantage that they do not require a mechanical bearing for the rotor. The rotor is supported or stabilized using the magnetic force generated by the stator of the magnetic bearing device. Due to the absence of a mechanical bearing, such magnetic bearing devices are particularly suitable for pumping, mixing, centrifuging or stirring devices in which very delicate substances are conveyed, such as blood pumps, or for which very high demands are made regarding purity, for example in the pharmaceutical or biotechnology industries, or in which destructive or aggressive substances that would destroy mechanical bearings very quickly are conveyed, such as pumps or mixers for slurries, sulfuric acid, phosphoric acid or other chemicals in the semiconductor industry.

[0003] In the biotechnology industry, such magnetic bearing devices are used, for example, in connection with bioreactors, for example in centrifugal pumps for transporting fluids into or out of bioreactors, or in mixing devices for mixing fluids within bioreactors. In the semiconductor industry, such magnetic bearing devices are not only used to transport aggressive or destructive substances, but also in rotating devices in which, for example, wafers are rotated.

[0004] It is also known to use magnetic bearing devices in viscometers.

[0005] A known advantage and design of the magnetic bearing device itself is the design of the temple structure, to which the present invention also relates.

[0006] A distinctive feature of the temple structure is that the stator of the magnetic bearing device has multiple coil cores, each with a longitudinal leg extending axially from a first end to a second end. Here, the axial direction refers to the direction defined by the desired axis of rotation of the rotor supported by the magnetic bearing device. The desired axis of rotation is the axis about which the rotor rotates in an operating state when the rotor is centered and not tilted relative to the stator. In addition to the longitudinal leg, each coil core also has a transverse leg, also called a pole shoe, which is located at the second end of the longitudinal leg in each case and extends radially, usually inward, perpendicular to the axial direction. Thus, the transverse leg extends approximately perpendicular to the longitudinal leg. Each coil core has an L-shape, with the transverse leg forming the shorter leg of the L. The rotor to be supported is then positioned between the transverse legs.

[0007] The longitudinal legs, extending axially and reminiscent of temple columns, give the structure its name.

[0008] In one design, the stator of a magnetic bearing device has, for example, six coil cores arranged equidistantly around a cup-shaped recess into which the rotor can be inserted. The first ends of the longitudinal legs are typically connected circumferentially by a back iron, which functions to transmit magnetic flux. The rotor to be supported comprises a magnetically effective core, such as a permanent magnetic disk or ring, disposed between the radially inner ends of the transverse legs, which rotates axially in operation, and the rotor is magnetically supported without contact with the stator.

[0009] For such magnetic bearing devices, the magnetically effective core of the rotor does not necessarily have to be designed in a permanent magnetic manner. Designs are also known in which the magnetically effective core of the rotor is designed in a non-permanently magnetic manner, i.e. without permanent magnets. In this case, the magnetically effective core of the rotor is, for example, designed in a ferromagnetic manner and is made, for example, of iron, nickel-iron, cobalt-iron, silicon-iron, mu-metal or another ferromagnetic material.

[0010] Furthermore, the magnetically effective core of the rotor can be designed to include both ferromagnetic and permanent magnetic materials. For example, permanent magnets can be disposed within or inserted into a ferromagnetic substrate. Such a design can be advantageous, for example, when it is desired to reduce the cost of large rotors by reducing the amount of permanent magnetic material.

[0011] The longitudinal legs carry windings to generate the electromagnetic fields required for the rotor's contactless magnetic bearing. For example, the windings are designed so that one concentrated winding is wound around each longitudinal leg, i.e., the coil axis of each concentrated winding extends axially in each case. Here, it is typical for a temple design that the coil axis of the concentrated windings extends axially and that the concentrated windings are not located in the radial plane in which the rotor or its magnetically active core is supported in operation.

[0012] In some designs, exactly one concentrated winding is located on each longitudinal leg. In other designs, several, for example exactly two, concentrated windings are provided on each longitudinal leg. In other designs, windings are wound around two circumferentially adjacent longitudinal legs, so that both of these two adjacent longitudinal legs are located within the interior space of the concentrated winding.

[0013] The coil cores of magnetic bearing devices known from the state of the art are usually designed with sheet metal, which means that several sheets of metal in the shape of the coil core are stacked circumferentially and insulated from each other.

[0014] The sheet metal design of the coil core blocks eddy currents associated with magnetic fields that extend in the direction of the sheet metal, i.e., fields that follow the longitudinal legs axially and the lateral legs radially.

[0015] For the magnetic fields emerging from the sheet metal of the longitudinal and lateral legs in the transverse, i.e. circumferential, direction, the sheet metal insulation is ineffective, and therefore these fields pass perpendicularly through the sheet metal, and eddy currents still occur.

[0016] In particular, for magnetic bearing devices with large magnetic gaps, defined as the distance between the end faces of the pole pieces and the magnetically effective core of the rotor in the radial direction, the orthogonal field components cannot be ignored, resulting in significant eddy current losses.

[0017] In the context of this application, a large magnetic gap means a magnetic gap that is greater than 1% of the diameter of the magnetically effective core in the radial direction, and in some cases the magnetic gap may be 5% or more of the diameter of the magnetically effective core in the radial direction. [Prior art documents] [Patent documents]

[0018] [Patent Document 1] European Patent Application Publication No. 4084304 Summary of the Invention [Problem to be solved by the invention]

[0019] Starting from this state of the art, the object of the invention is therefore to propose a magnetic levitation device for contactless magnetic levitation of a rotor with a disk-shaped or ring-shaped magnetically effective core, which has lower eddy current losses than the previous state of the art.

[0020] Furthermore, the object of the invention is to propose an electromagnetic rotary drive mechanism equipped with such a magnetic levitation device.

[0021] The subject matter of the invention which meets this object is characterized by the features of the independent patent claims. [Means for solving the problem]

[0022] According to the present invention, a magnetic levitation device is thus proposed for contactless magnetic levitation of a rotor having a disk-shaped or ring-shaped magnetically effective core, the magnetic levitation device comprising a stator with a cup-shaped recess arranged at its axial end, into which the rotor can be inserted, the stator having a plurality of coil cores, each of which has a longitudinal leg and a pole piece, each longitudinal leg extending axially from a first end to a second end, a contact surface arranged at the second end, each pole piece extending at least partially radially from the contact surface to an end face, the radial direction being perpendicular to the axial direction, the end face being arranged around the cup-shaped recess, at least one concentrated winding arranged on each longitudinal leg and surrounding the respective longitudinal leg, each pole piece being made of sheet metal transverse elements, the transverse elements being axially stacked.

[0023] Since the distance between adjacent pole pieces is particularly small, especially at their ends facing the cup-shaped recess, most eddy current losses occur in the pole pieces. The reason for this is that eddy current losses arise mainly from cross-fields, i.e., fields that penetrate the transverse elements at right angles. Such cross-fields have the potential to flow circumferentially from the pole pieces of a first coil core to the pole pieces of a second, adjacent coil core, especially with the small distance between the pole pieces. Due to the axially stacked transverse elements of the pole pieces, the cross-fields in the circumferential direction are blocked. This results in a dramatic reduction in eddy current losses.

[0024] This results in another important advantage: the end faces of the pole pieces can be arranged closer together in the circumferential direction, since the field flowing circumferentially from the pole piece of a first coil core to the pole piece of a second adjacent coil core flows parallel to the axially stacked transverse elements and thus does not generate any eddy current losses. In this way, for example, the passive stiffness and the active levitation force can be improved and / or a more compact structure of the stator is possible.

[0025] The attachment of the pole piece to the longitudinal leg can be performed using several possible joining methods. These include, among others, force-locking joining methods such as clamping or crimping, form-locking joining methods such as screwing or plugging, or material-locking connections such as gluing. The connection between the longitudinal leg and the pole piece can also be made via tongue and groove and / or plugs such as pins, sharp points or dovetails. In a preferred embodiment, the material-locking joining method is achieved by gluing.

[0026] According to one preferred embodiment, each longitudinal leg is made of a longitudinal element of sheet metal, the longitudinal elements being stacked in the circumferential direction of the stator.

[0027] According to a preferred embodiment, the transverse and / or longitudinal elements are made of electrical sheet metal.

[0028] According to a common definition, electrical sheet metal is understood to be a soft magnetic material for magnetic coils. Materials with low coercivity are usually called soft magnetic materials. Coercivity is the magnetic field strength required to remove magnetism from a material. Within the framework of this application, soft magnetic materials are understood to be materials with a coercivity, more precisely, with a magnetic polarization of less than 2,000 A / m.

[0029] There is also the possibility of using mu metal for the transverse and / or longitudinal elements.

[0030] According to a preferred embodiment, the contact surface is designed in a planar manner and is arranged on the surface of the longitudinal leg perpendicular to the radial direction, in which case the contact surface is particularly preferably arranged on the second end of the longitudinal leg.

[0031] According to a preferred embodiment, the end face of the pole piece is designed as a curved surface. It is particularly preferred that the end face is designed and arranged coaxially with respect to the cup-shaped recess. In other words, the end face of the pole piece is a section of a cylindrical surface, the central axis of which coincides with the central axis of the cup-shaped recess and the radius of which is greater than that of the cup-shaped recess, so that the end face does not protrude into the cup-shaped recess.

[0032] Furthermore, the end face is preferably designed to be wider in the circumferential direction than the maximum extension of the contact surface in the circumferential direction. This means that one of the two circumferentially extending edges of the end face is longer than one of the circumferentially extending edges of the contact surface. If the end face is designed as a curved surface, the length of one of the arcs of the section of the cylindrical surface in the radial plane is greater than the length of one of the circumferentially extending edges of the contact surface.

[0033] Such widening of the end faces in the circumferential direction has the advantage that magnetic function is facilitated, for example, passive stiffness and active levitation can be improved.

[0034] A further advantage arises in combination with the embodiment of the pole shoes with transverse elements: the end faces can be made considerably wider in the circumferential direction, i.e., their extension in the circumferential direction can be considerably greater than the end faces of coil cores known from the state of the art. Conversely, the distance between the two end faces of two adjacent coil cores can be significantly reduced. The reason for this is that the field emerging laterally from the pole shoes flows parallel to the axially stacked transverse elements, so no additional eddy currents are created.

[0035] According to a preferred embodiment, the end face has at least one slot extending in the axial direction, which means that the at least one slot can extend axially into the end face for any length.

[0036] According to one preferred embodiment, at least one slot extends from a first axial end of the pole piece to a second axial end of the pole piece, this extension thus being the maximum possible extension of the slot in the end face in the axial direction.

[0037] In one possible embodiment where the end face has two or more slots, one slot can extend axially from a first end of the pole piece and a second slot can extend in the opposite axial direction from the second slot to the first slot in the axial direction of the pole piece. In this case, each of the two slots can have an axial extension that is less than 50% of the axial extension of the end face. In other words, this means that the end face has two slots that do not meet in the center of the end face, and therefore there is at least one transverse element of the pole piece that is not captured by the slot.

[0038] Providing at least one slot in the end face of the coil core provides electrical insulation. This means that the at least one slot ensures that the path of eddy currents in the transverse elements of the pole pieces is interrupted and thus blocked. This prevents eddy currents arising from the magnetic field emerging from the transverse elements in the axial direction. As a result, only small eddy currents remain in the coil core, and overall eddy current losses in the coil core are dramatically reduced. It is advantageous here for the at least one slot to run parallel, or at least approximately parallel, to the path of the magnetic field in the transverse elements of the pole pieces so as not to block the path.

[0039] Several different methods can be used to create the slots: among others, these include mechanical processes such as milling, punching or cutting, whereby the latter also includes the use of laser and / or water jet cutters and / or wire erosion.

[0040] Furthermore, the radial extension of the at least one slot is preferably smaller than the radial extension of the pole piece. In a preferred embodiment, the radial extension of the at least one slot is 5-30% of the area of ​​the radial extension of the pole piece. The extension can also be more than 30% of the extension of the pole piece, for example 40%, 50%, or even 99%. A larger radial extension of the at least one slot is possible, especially in designs in which the at least one slot does not extend through all the transverse elements of the pole piece. In this case, it is even conceivable that 100% could be achieved.

[0041] According to a preferred embodiment, several slots are arranged parallel to one another in the end face, or at least approximately parallel, whereas in an advantageous embodiment several slots are arranged perpendicular to the end face.

[0042] An arrangement of several slots parallel to one another is advantageous because this means that they do not obstruct the path of the magnetic field, as they also run parallel, or at least approximately parallel, to the path of the magnetic field within the coil core.

[0043] According to one preferred embodiment, each coil core has a rounded portion at its upper axial end, which changes the direction of the coil core from axial to radial.

[0044] For example, in the case of an L-shaped coil core, the long part of the "L" is formed by the longitudinal legs, and the short part of the "L" is formed by the pole pieces, and the radially outer edges of the pole pieces are designed to extend in a radial plane circumferentially and be rounded when viewed from the cup-shaped recess. This embodiment has the advantage that it has lower eddy current losses and is easier to realize in terms of structure. This embodiment can be realized with all possible embodiments of the end faces and pole pieces or longitudinal legs.

[0045] According to a preferred embodiment, each coil core has a first lateral boundary surface and a second lateral boundary surface, and at least one of the first and second lateral boundary surfaces has at least one slot. Providing a slot in at least one of the two lateral boundary surfaces of the coil core provides electrical insulation. This means that the at least one slot ensures that the path of eddy currents in the coil core is interrupted and thus blocked. As a result, only small eddy currents remain in the coil core, and overall eddy current losses in the coil core are dramatically reduced. In this case, it is advantageous for the at least one slot to run parallel to, or at least approximately parallel to, the path of the magnetic field so as not to block it.

[0046] How far the at least one slot extends axially within the longitudinal leg toward the first end of the longitudinal leg can vary, with all lengths of the at least one slot being possible, from a small extension of 5% of the total axial length of the longitudinal leg to an extension toward the first end of the longitudinal leg.

[0047] At least one slot may have a rounded portion that changes the direction of the slot from radial to axial.

[0048] In some embodiments, at least one slot extends from the first lateral boundary surface to the second lateral boundary surface.

[0049] In other embodiments, the extension of at least one slot may be less than the distance from the second lateral boundary surface to the first lateral boundary surface when viewed in the circumferential direction of the stator.

[0050] In other words, at least one slot does not extend through the entire coil core in the circumferential direction of the stator. This means that at least one slot is not provided in all longitudinal elements of the sheet metal design of the coil core. This is advantageous because the majority of eddy currents occur primarily in longitudinal elements located directly at or close to the two lateral boundary surfaces. Thus, the paths of eddy currents in the coil core are interrupted by at least one slot at the location where they occur most frequently. This ensures a significant reduction in eddy current losses. Furthermore, this embodiment is advantageous for the stability of the coil core.

[0051] An embodiment is also possible in which several slots are provided that are arranged parallel to one another, where the arrangement of several slots parallel to one another is advantageous since they thereby extend parallel, or at least approximately parallel, to the path of the magnetic field in the coil core and therefore do not interfere with the path of the magnetic field.

[0052] The slots can be produced using several different methods: among others, these include mechanical processes such as milling, punching or cutting, whereby the latter also includes laser or water jet cutters.

[0053] According to one particularly preferred embodiment, a back iron is arranged at the first end, which connects the first ends of all the longitudinal legs, and the back iron is designed in a ring shape with metal strips extending from a radially inner starting point to a radially outer end, the strips forming several strip windings lying flat against each other in the radial direction.

[0054] According to one particularly preferred embodiment, the stator of the magnetic levitation device is designed to generate a torque capable of magnetically driving the rotor to rotate axially without contact.

[0055] Here, the stator is designed as a bearing and a drive stator, both of which are stators of an electric drive mechanism and of a magnetic levitation. The electrical windings of the stator can be used to generate a rotating magnetic field which, on the one hand, exerts a torque on the rotor, causing it to rotate about the desired axis of rotation, and, on the other hand, exerts a freely adjustable transverse force on the rotor, thereby actively controlling or adjusting its radial position.

[0056] Particularly for embodiments in which the magnetic levitation device is designed to generate torque, this embodiment with wider end faces is advantageous because the magnetic function is thus enhanced, for example, increased torque can be generated or the passive stiffness or active levitation force can be improved.

[0057] Furthermore, the present invention proposes an electromagnetic rotary drive mechanism designed as a temple motor, which comprises a magnetic levitation device according to the present invention as well as a rotor with a disk-shaped or ring-shaped magnetically effective core, which rotor can be inserted into a cup-shaped recess, and which rotor is designed as a rotor of the electromagnetic rotary drive mechanism.

[0058] Such electromagnetic rotary drives are also known as bearingless motors, a term that refers to an electromagnetic rotary drive in which the rotor is entirely magnetically levitated relative to the stator and does not have a separate magnetic bearing.

[0059] Further advantageous measures and embodiments of the invention are evident from the dependent claims.

[0060] In the following, the invention will be explained in more detail with reference to examples and with reference to the drawings. [Brief explanation of the drawings]

[0061] [Figure 1] 1 is a perspective view of a first embodiment of a magnetic levitation device according to the present invention; [Figure 2] FIG. 2 is a perspective view of a single coil core of the magnetic levitation device from Figure 1. [Figure 3] FIG. 3 is a perspective view of a first variant of the coil core from FIG. 2; [Figure 4] An enlarged view of the pole pieces of the coil core from Figure 3. [Figure 5] 3 is a perspective view of a second variant of the coil core from FIG. 2; [Figure 6] 1 is a perspective view of a second embodiment of a magnetic levitation device according to the present invention; [Figure 7] FIG. 7 is a perspective view of a single coil core of the magnetic levitation device from Figure 6. [Figure 8] FIG. 10 is a perspective view of a third embodiment of a magnetic levitation device according to the present invention. [Figure 9] 1 is a schematic cross-sectional view of one embodiment of a stator housing. DETAILED DESCRIPTION OF THE INVENTION

[0062] FIG. 1 shows a perspective view of an embodiment of a magnetic levitation device according to the invention, which is designated in its entirety by the reference number 1. The magnetic levitation device 1 is designed for contactless magnetic levitation of a rotor 3, which comprises a disk-shaped or ring-shaped magnetically active core 31. The magnetic levitation device 1 is designed according to a temple structure and comprises a stator 2. Normally, the stator 2 comprises a stator housing 21 (FIG. 9), which is not represented in FIG. 1 for the sake of a better overview. In a schematic cross-sectional view, FIG. 9 therefore illustrates one embodiment of the stator housing 21.

[0063] A cup-shaped recess 211 is provided at one axial end of the stator housing 21, into which the rotor 3 can be inserted. The rotor 3 is designed to rotate about a desired axis of rotation. This desired axis of rotation defines an axial direction A. Typically, the central axis of the stator 2 extends in the axial direction A and coincides with the desired axis of rotation. The desired axis of rotation specifies the axis about which the rotor 3 rotates in an operational state when the rotor 3 is centered and not tilted relative to the stator 2, as depicted in FIG. 1.

[0064] The stator 2 has a plurality of coil cores 25, six in this example, each of which has a longitudinal leg 26 and a pole piece 27. Each longitudinal leg 26 extends from a first end 261 in the axial direction A to a second end 262, with a contact surface 271 located at the second end 262, from which each pole piece 27 extends at least partially in the radial direction R to an end face 272, where the end face 272 faces the rotor 3 and is disposed around it. In other words, the pole pieces 27 of the coil cores 25 are disposed such that the end faces 272 of the pole pieces 27 are disposed around the cup-shaped recess 211. The coil cores 25 of the stator 2 are disposed equidistantly on a circular line, so that the end faces 272 surround the magnetically active core 31 of the rotor 3 when the rotor 3 is inserted into the cup-shaped recess 211.

[0065] In this embodiment, the contact surface 271 is designed in a planar manner and is arranged on the surface of the longitudinal leg 26 perpendicular to the radial direction R.

[0066] For better understanding, a perspective view of a single coil core 25 of the magnetic bearing device 1 from FIG. 1 is represented in FIG.

[0067] At least one concentrated winding 61 is arranged on each longitudinal leg 26, which surrounds the respective longitudinal leg 26. In other embodiments, two or more concentrated windings may be arranged on the longitudinal legs 26. For example, as depicted here in Fig. 1, there are embodiments in which exactly two concentrated windings 61a, 61b are provided in each of the longitudinal legs 26 in each case, each of which surrounds the respective longitudinal leg 26, in which the two windings 61a, 61b arranged on the same longitudinal leg 26 are arranged adjacent to each other with respect to the axial direction A.

[0068] The concentrated windings 61 function to generate an electromagnetic field that allows the rotor 3 to be magnetically levitated (FIG. 9) without contacting the cup-shaped recess 211.

[0069] In a first embodiment of the magnetic levitation device 1 according to the invention, represented in FIG. 1, the pole pieces 27 are made of transverse elements 273 of sheet metal, which are stacked in the axial direction A.

[0070] Due to the transverse elements 273 of the axially stacked pole pieces 27, the circumferentially flowing fields are propagated parallel to the sheet metal plane. In this way, eddy current losses are dramatically reduced.

[0071] This leads to another important advantage. Since the field flowing circumferentially from the pole piece 27 of a first coil core 25 to the pole piece 27 of a second adjacent coil core 25 does not result in any additional eddy current losses, the end faces 272 of the pole pieces 27 can be positioned closer to each other in the circumferential direction. This can improve, for example, the passive stiffness and active levitation, and / or allow for a more compact stator design. The pole pieces 27 can be attached to the longitudinal legs 26 using several possible joining methods. These include, among others, force-locking joining methods such as clamping or crimping, form-locking joining methods such as screwing or plugging, or material-locking connections such as adhesive bonding. It is also possible to connect the longitudinal legs 26 and the pole pieces 27 via tongue and groove joints and / or plugs such as pins, sharp points, or dovetail joints. In a preferred embodiment, the material-locking joining method is achieved by adhesive bonding.

[0072] Here, the end face 272 of the pole piece 27 is designed as a curved surface, which is arranged coaxially with respect to the cup-shaped recess 211. In this case, the end face 272 is designed to be wider in the circumferential direction than the maximum extension of the contact surface 271 in the circumferential direction. The circumferential direction refers to the direction that is perpendicular to the radial direction R and also perpendicular to the axial direction A.

[0073] Therefore, the end face 272 of the pole piece 27 can be considered as a section of a cylindrical surface, the central axis of which coincides with the central axis of the cup-shaped recess 211, which in this embodiment is the axis of the axial direction A, and its radius is larger than that of the cup-shaped recess 211, so that the end face 272 does not protrude into the cup-shaped recess 211.

[0074] In other words, one of the two edges 2721 or 2722 of the circumferentially extending end face 272 is longer than one of the edges 2711 or 2712 of the circumferentially extending contact surface. If the end face 272 is designed as a curved surface, the length of one of the arcs 2721 or 2722 of the cylindrical surface section in the radial plane is greater than the length of one of the edges 2711 or 2712 of the circumferentially extending contact surface 271. The radial plane is indicated in FIG. 1 by the line of the radial direction R, which is perpendicular to the axial direction A. The radial plane is the plane that is perpendicular to the axial direction A and encompasses the radial direction R. The radial plane is the plane in which the magnetically active core 31 of the rotor 3 is actively magnetically levitated between the end faces 272 of the stator 2 in the operating state. When the rotor 3 is not tilted and not deflected in the axial direction A, the magnetic center plane lies in a radial plane, which defines the xy plane of a Cartesian coordinate system with the z axis extending in the axial direction A.

[0075] The radial position of the magnetically effective core 31 or rotor 3 refers to the position of the rotor 3 in a radial plane.

[0076] In this embodiment, the longitudinal legs 26 are also made of sheet metal longitudinal elements 263 which are stacked in the circumferential direction of the stator 2 .

[0077] The longitudinal elements 263 and transverse elements 273 can be made of electrical sheet metal, which by common definition is understood to be a soft magnetic material for the magnetic core. There is also the possibility of using mu metal for the strips.

[0078] The number of vertical elements 263 and horizontal elements 273 in all examples and figures should be understood as purely exemplary: the numbers may be greater or even less than those shown.

[0079] According to a particularly preferred embodiment, the stator 2 is designed such that, in addition to contactless magnetic levitation of the rotor 3, it can also exert a torque on the rotor 3 or on the magnetically effective core 31 of the rotor 3, driving the rotor 3 to rotate about a desired axis of rotation. This means that in this preferred embodiment, the rotor 3 can be driven to rotate about an axial direction A.

[0080] The already mentioned widening of the end face 272 in the circumferential direction has the advantage that magnetic function is thus facilitated, for example, passive stiffness and active levitation can be improved. For embodiments in which the magnetic levitation device 1 is designed to generate torque, there is also the advantage that increased torque can be generated.

[0081] In this embodiment, the concentrated windings 61 a, 61 b ​​thus generate a rotating electromagnetic field that can be used to magnetically levitate the rotor 3 without contact with respect to the stator 2, and also to drive it to rotate about the axial direction A without contact.

[0082] It is understood that the number of six coil cores 25, while preferred, should be understood as merely illustrative. Of course, embodiments in which the stator 2 has fewer than six coil cores 25, for example, five, four, or three coil cores 25, or embodiments in which the stator 2 has more than six coil cores 25, for example, seven, eight, or nine coil cores 25, or any other number of coil cores 25, are also possible.

[0083] The rotor 3 comprises a magnetically effective core 31, which is designed in a ring- or disc-shaped manner. According to the representation in Fig. 1, the magnetically effective core 31 is designed as a ring and defines a magnetic center plane. Alternatively, the magnetically effective core 31 can be designed as a disc. Usually, in the case of a disc- or ring-shaped magnetically effective core 31, the magnetic center plane is the geometric center plane of the magnetically effective core 31 of the rotor 3, which is perpendicular to the axial direction A. In operation, the magnetically effective core 31 is levitated in a radial plane that is perpendicular to the axial direction A.

[0084] Only the magnetically effective core 31 of the rotor 3 is depicted in Figure 1, as this is sufficient for understanding the present invention. It will be understood that the rotor 3 may of course also comprise further components, such as an outer casing or encapsulation vessel, which are preferably made of plastic, or a metal or metal alloy, or a ceramic or ceramic material. Furthermore, the rotor 3 may also comprise blades for mixing, stirring or pumping fluids or other components.

[0085] When the rotor 3 is inserted into the cup-shaped recess 211 (FIG. 9), the rotor 3 and in particular its magnetically effective core 31 are surrounded by the radially outwardly arranged end faces 272 of the pole pieces 27 of the coil core 25 of the stator 2. The pole pieces 27 thus form a number of prominently visible stator poles, in this case six stator poles.

[0086] When the magnetically active core 31 of the rotor 3 is in its desired position during operation, the magnetically active core 31 is centered between the end faces 272 of the pole pieces 27. According to this expression, the concentrated windings 61 are disposed below a radial plane and are aligned with their coil axes extending in the axial direction A.

[0087] All first ends 262 of the longitudinal legs 26, i.e., lower ends 261 according to the representation (FIG. 1), are connected to one another by a back iron 28. The back iron 28 is preferably designed in a ring-shaped manner. Such an embodiment is possible in which the back iron 28 extends radially inward along all first ends 261 of the longitudinal legs 26 (see, for example, FIG. 1).

[0088] In order to generate the electromagnetic fields required for magnetic levitation of the rotor 3 and, optionally, for generating torque on the rotor 3, the longitudinal legs 26 of the coil core 25 carry windings designed as concentrated windings 61.

[0089] In operation, such rotating electromagnetic fields are generated by such concentrated windings 61 and can be used to exert arbitrarily adjustable radial transverse forces on the rotor 3, thereby actively controlling or adjusting the radial position of the rotor 3, i.e., its position in a radial plane perpendicular to the axial direction A. Optionally, these rotating electromagnetic fields are used to additionally provide a torque on the rotor 3.

[0090] The "magnetically active core 31" of the rotor 3 refers to that region of the rotor 3 that magnetically cooperates with the stator 2 for the generation of magnetic levitation forces, and optionally torque generation.

[0091] As already mentioned, the magnetically effective core 31 is designed in this embodiment in a ring-shaped manner. Furthermore, the magnetically effective core 31 is designed in a permanent magnetic manner. To this end, the magnetically effective core 31 comprises at least one permanent magnet, but may also comprise several permanent magnets, or, as in the embodiment described here, is entirely made of a permanent magnetic material, so that the magnetically effective core 31 is a permanent magnet. For example, the magnetically effective core 31 is magnetized in the radial direction.

[0092] Such ferromagnetic or ferrimagnetic materials are magnetically hard and have a high coercivity, and are typically called permanent magnets. Coercivity is the magnetic field strength required to remove magnetism from a material. Within the framework of this application, a permanent magnet is understood as a component or material that has a coercivity, more precisely, a coercivity of magnetic polarization greater than 10,000 A / m.

[0093] Such an embodiment is also possible in which the magnetically active core 31 is designed without permanent magnets, i.e. has no permanent magnets. The rotor 3 is then designed, for example, as a reluctance rotor. The magnetically active core 31 of the rotor 3 is then made, for example, of a soft magnetic material. Suitable soft magnetic materials for the magnetically active core 31 are, for example, ferromagnetic or ferrimagnetic materials, i.e., in particular iron, nickel-iron, cobalt-iron, silicon-iron, mu-metal.

[0094] Furthermore, embodiments are possible in which the magnetically effective core 31 of the rotor 3 comprises both ferromagnetic and permanent magnetic materials. For example, permanent magnets can be disposed or inserted into a ferromagnetic substrate. Such embodiments are advantageous, for example, when it is desired to reduce the cost of large rotors by saving permanent magnetic material.

[0095] An embodiment is also possible in which the rotor is designed according to the squirrel cage rotor principle.

[0096] The stator 2 is free of permanent magnets. Within the framework of the present application, the statement that the stator 2 is designed "without permanent magnets" should be understood to mean that the stator 2 does not comprise any permanent magnets that substantially contribute to the driving field for driving the rotation of the rotor 3 or for generating the magnetic levitation force of the rotor 3. Thus, the magnetic flux generated by the stator 2 for driving and levitating the rotor 3 does not include permanently magnetically excited magnetic flux.

[0097] Of course, the rotor 3 and / or stator 2 may also comprise other magnets or permanent magnets within the sensor that function, for example, to capture the angular position of the rotor or otherwise serve a purpose unrelated to generating magnetic flux for driving and levitating the rotor 3.

[0098] Thus, the phrase "no permanent magnets" refers only to the generation of magnetic flux by the stator 2 to drive and levitate the rotor 3. In other words, the stator 2 does not have any permanent magnets that contribute to the magnetic flux by which the rotor 3 is driven and magnetically levitated.

[0099] However, the magnetic flux for driving and levitating the rotor 3 comprises a permanent magnetic flux, which can then also simply be generated by the rotor 3 itself, which is the case when the rotor 3 itself is equipped with permanent magnets.

[0100] The ring-shaped back iron 28 can be made of a soft magnetic material, which is well suited to transmitting magnetic flux, and the coil core 25 of the stator 2 can also be made of a soft magnetic material.

[0101] Suitable soft magnetic materials for the coil core 25 and the back iron 28 are, for example, ferromagnetic or ferrimagnetic materials, i.e., in particular, iron, nickel-iron, cobalt-iron, silicon-iron, or mu-metal. In this case, a design as a stator sheet metal stack is preferred for the stator 2, in which the back iron 28 is designed from sheet metal, i.e., it is composed of several thin sheet metal elements, also called back iron elements 283, stacked parallel to one another in the axial direction A. All back iron elements 283 are designed identically, i.e., in this case, substantially ring-shaped and with the same thickness in each case. Thus, the back iron 28 itself is designed substantially ring-shaped and, in the assembled state, extends radially inward along the first end 261 of the longitudinal leg 26.

[0102] An embodiment is also possible in which a so-called tape-wound toroidal core is used as the back iron 28. This is a coiled strip 29. Such a design is realized in the third embodiment depicted in FIG.

[0103] Furthermore, the back iron 28 can be composed of pressed and then sintered particles of the above-mentioned materials. The metal particles are preferably embedded in a plastic matrix, so that they are at least partially insulated from one another, thereby minimizing eddy current losses. Thus, soft magnetic composites composed of electrically insulated, compressed metal particles are also suitable for the stator. Specifically, such soft magnetic composites, also designated as SMCs (soft magnetic composites), can be composed of iron powder particles coated with an electrically insulating layer. Such SMCs are then formed into the desired shape using a powder metallurgy process.

[0104] During operation of the magnetic levitation device 1, the magnetically active core 31 of the rotor 3 cooperates with the stator 2 in such a way that the rotor 3 can be magnetically levitated without contact with respect to the stator 2 and, preferably, can also be magnetically set to rotate about the axial direction A without contact. In this case, it is particularly advantageous that the same windings 61 that provide magnetic levitation of the rotor 3 also function to generate torque on the rotor 3. Preferably, three degrees of freedom of the rotor 3 can then be actively adjusted, i.e., its position in the radial plane and its rotation can be actively adjusted. With respect to its axial deflection from the radial plane of the axial direction A, the magnetically active core 31 of the rotor 3 is passively magnetically stabilized by reluctance forces, i.e., it cannot be controlled. The magnetically active core 31 of the rotor 3 is also passively magnetically stabilized with respect to the remaining two degrees of freedom, i.e., with respect to tilting with respect to a radial plane perpendicular to the axis of desired rotation. By cooperation of the coil core 25 and the magnetically active core 31, the rotor 3 is thus passively magnetically levitated or passively magnetically stabilized against tilt in the axial direction A (all three degrees of freedom), and actively magnetically levitated in the radial plane (two degrees of freedom).

[0105] As is common in that case, active magnetic levitation also refers within the framework of this application to something that can be actively controlled or regulated, for example by means of an electromagnetic field generated by concentrated windings 61. Passive magnetic levitation or passive magnetic stabilization is something that cannot be controlled or regulated. Passive magnetic levitation or passive magnetic stabilization is, for example, based on reluctance forces that return the rotor 3 to its desired position again when it is deflected from its desired position, i.e., when it is displaced or deflected, for example, in the axial direction A, or when it is tilted.

[0106] In contrast to conventional magnetic bearings, in magnetic levitation device 1, magnetic levitation, and optionally the generation of torque acting on the rotor, is achieved using a rotating electromagnetic field. With regard to the combined generation of magnetic levitation force and torque for rotation of rotor 3 about axial direction A, on the one hand, it is possible to place exactly one concentrated winding 61 on each longitudinal leg 26, as shown in FIG.

[0107] On the other hand, embodiments are also possible in which two different winding systems are provided for the combined generation of magnetic levitation forces and torque for rotating the rotor 3. For this purpose, for example, as depicted in Fig. 1, exactly two concentrated windings 61a, 61b are arranged in each case on each longitudinal leg 26, which are arranged adjacent to each other with respect to the axial direction A. One of the two windings 61a, 61b belongs to the first of the two winding systems, and the other belongs to the second of the two winding systems.

[0108] 8, with exactly one concentrated winding 61 on each coil core 25, for example, the values ​​of the current required for levitation and the current required for torque generation, determined in each case in the control unit, are added or summed by calculation, for example with the aid of software, and the resulting total current is then applied to the respective concentrated winding 61.

[0109] If the stator 2 of the magnetic levitation device 1 according to the present invention is designed to generate torque, the magnetic levitation device 1 is suitable for an electromagnetic rotary drive mechanism designed as a temple motor. The magnetic levitation device 1 according to the present invention may also be suitable for other devices such as centrifugal pumps, mixing devices for mixing flowable substances, e.g., stirring devices for mixing fluids in tanks, fans, or devices for supporting and rotating wafers in semiconductor manufacturing, for example.

[0110] Figure 3 is a perspective view of a first variant of the coil core 25 from Figure 2. One difference from the first variant is that the end face 272 has at least one slot 2724, which extends from the first axial end 274 of the pole piece 27 to the second axial end 275 of the pole piece 27. For further understanding, an enlarged view of the pole piece 27 of the coil core 25 from Figure 3 is represented in Figure 4.

[0111] The provision of at least one slot 2724 in the end face 272 of the coil core 25 provides electrical insulation. This means that the at least one slot 2724 ensures that the path of eddy currents in the transverse elements 273 of the pole pieces 27 is interrupted and thus obstructed. As a result, only small eddy currents remain in the coil core 25, and the overall eddy current losses in the coil core 25 are dramatically reduced. Here, it is advantageous for the at least one slot 2724 to extend parallel or approximately parallel to the path of the magnetic field in the transverse elements 273 of the pole pieces 27 so as not to obstruct it.

[0112] Several different methods can be used to create the slot 2724. These include, among others, mechanical processes such as milling, punching or cutting, whereby the latter also includes the use of lasers and / or water jet cutters and / or wire erosion.

[0113] In this variant of the coil core 25, several slots 2724, here five slots 2724, are arranged parallel to one another in the end face 272. The number of slots 2724 in all embodiments and figures should be understood as purely illustrative. The number may be greater or less than that shown. It is also possible that the slots 2724 may only be approximately parallel to one another, such as being inclined or curved relative to one another. Here, it is important that they follow the path of the magnetic flux field. This depends, inter alia, on the outer shape of the pole pieces 27 or transverse elements 273.

[0114] In this embodiment, the extension T of the slot 2724 in the radial direction R is less than the extension L of the pole piece 27 in the radial direction R.

[0115] In a preferred variant, the extension T of the at least one slot 2724 in the radial direction R lies within an area of ​​5 to 30% of the extension L of the pole piece 27 in the radial direction R. It is also possible for the extension T to have an extension of more than 30% of the extension L of the pole piece 27, for example 40%, or 50% or even more than 99% thereof.

[0116] For the embodiment of the coil core 25 depicted here, in which the end face 272 is designed as a curved surface, it applies that the extension T should be determined individually for each individual slot 2724, since the length L is different at each point on the edge 2722 due to the curvature. For this reason, the slots 2724 in this variant of the coil core 25 have different extensions T compared to each other.

[0117] Coil core 25 variations are also possible in which the slots 2724 all have the same extension T. This can be the case for coil cores 25 with curved end faces 272 as well as for coil cores 25 with non-curved end faces 272, as in the variation of coil core 25 in FIG. 2. Of course, it is also possible that slots 2724 may have different extensions T in the case of non-curved end faces 272.

[0118] Figure 5 shows a perspective view of a second variant of the coil core 25 from Figure 2. In the following description of the second variant of the coil core, only the differences from the first variant from Figures 3 / 4 are explained in more detail. The description of the first variant also applies in the same or similar way to the second variant. The same reference signs indicate the same or functionally equivalent features described with reference to the first variant.

[0119] A second variant of the coil core 25 has slots 2724 in the end face 272, which extend in the axial direction A but do not extend through all of the transverse elements 273. A first number of slots 2724 extend in the axial direction A from a first axial end 274 of the pole piece 27, and a second number of slots 2724 extend in the axial direction A from a second axial end 275 of the pole piece 27 opposite to the first number of slots 2724. In this case, the total extension TA of all slots 2724 in the axial direction A is in each case less than 50% of the extension SA of the end face 272 in the axial direction A. In other words, this means that the end face 272 has a first number of slots 2724 starting at a first axial end 274 and a second number of slots 2724 starting at a second axial end 275, such that the first number of slots 2724 and the second number of slots 2724 do not contact each other at the axial center AM of the end face 272, and therefore there will be at least one transverse element 273 of the pole piece 27 that is not captured by the slots 2724.

[0120] In this variant, it is even possible that the extension T of the at least one slot 2724 in the radial direction is equal to the extension L of the pole piece 27 in the radial direction R. FIG. 6 shows a perspective view of a second embodiment of the magnetic levitation device 1 according to the invention. For better understanding, a perspective view of an individual coil core 25 of the magnetic levitation device 1 from FIG. 6 is represented in FIG. 7. In the following description of the second embodiment of the magnetic levitation device 1, only the differences from the first embodiment from FIG. 1 will be explained in more detail. The explanation of the first embodiment also applies in the same or similar way to the second embodiment. The same reference signs indicate the same features or functionally equivalent features explained with reference to the first embodiment.

[0121] One difference is that each coil core 25 has a rounded portion 257 at its upper axial end 252, which changes the orientation of the coil core from the axial direction A to the radial direction R.

[0122] For example, in the case of an L-shaped coil core 25, the long part of the "L" is formed by the longitudinal leg 26, and the short part of the "L" is formed by the pole piece 27, and the radially outer edge 258 (FIGS. 1-3) of the pole piece 27 is designed to extend circumferentially in a radial plane and be rounded when viewed from the cup-shaped recess 211. This embodiment has the advantage that it has lower eddy current losses and is easy to realize in terms of structure. This embodiment can be realized with all possible embodiments of the end face 272 and the pole piece 27 or the longitudinal leg 26.

[0123] Each coil core 25 has a first side boundary surface 255 and a second side boundary surface 256, and at least one of the first side boundary surface 255 or the second side boundary surface 256 has at least one slot 254. In this embodiment, three slots 254 are arranged in each case on both the first side boundary surface 255 and the second side boundary surface 256. The slots 254 extend into the longitudinal legs 26. Providing the slots 254 on the two side boundary surfaces 255, 256 of the coil core 25 provides electrical insulation. This means that the slots 254 ensure that the path of eddy currents within the coil core 25 is interrupted and thus obstructed. As a result, only small eddy currents remain within the coil core 25, and eddy current losses in the coil core 25 are dramatically reduced overall.

[0124] In this embodiment, each of the slots 254 has a rounded portion 2541 that redirects the respective slot 254 from the radial direction R to the axial direction A. The slots 254 are arranged parallel to each other and parallel, or at least approximately parallel, to the path of the magnetic field in the coil core 25. This has the advantage that the slots 254 thereby do not block and / or interfere with the path of the magnetic field within the coil core 25.

[0125] In this embodiment, the extension of the slot 254 is shorter than the distance from the second lateral boundary surface 256 to the first lateral boundary surface 255 when viewed in the circumferential direction of the stator 2. In other words, the slot 254 does not penetrate all of the longitudinal elements 263 of the coil core 25, but only a certain number of them.

[0126] This is advantageous because the majority of eddy currents occur above all in the longitudinal elements 263, which are arranged directly or close to the two lateral boundary surfaces 255, 256. The paths of the eddy currents in the coil core 25 are thus interrupted by the slots 254 at the locations where they occur most frequently. This ensures that eddy current losses are significantly reduced. Furthermore, the incomplete penetration of the slots 254 through all the longitudinal elements 263 of the coil core 25 is advantageous for the stability of the coil core 25.

[0127] However, embodiments in which the slot 254 extends from the first lateral boundary surface 255 to the second lateral boundary surface 256 are also possible.

[0128] In this embodiment, the slot 254 does not extend over the entire extension of the longitudinal leg 26 in the axial direction A, but only partially, terminating before the upper axial end of the concentrated winding 61a.

[0129] Additionally, however, embodiments are also possible in which at least one slot 254 has a longer extension in the longitudinal leg 26 than in the embodiment depicted in Figure 7. One such possible embodiment is depicted in Figure 8.

[0130] 8 shows a perspective view of a third embodiment of the magnetic levitation device 1 according to the present invention. In the following description of the third embodiment of the magnetic levitation device 1, only the differences from the first and second embodiments from FIGS. 1 and 6 will be explained in more detail. The descriptions of the first and second embodiments also apply in the same or similar manner to the third embodiment. The same reference signs indicate the same features or functionally equivalent features described with reference to the first embodiment.

[0131] As already mentioned, one difference in the third embodiment is the extension of the slot 254 in the longitudinal leg 26, which is significantly longer than the extension of the slot 254 in the coil core 25 from the second embodiment. The maximum possible extension of the slot 254 in the longitudinal leg 26 terminates at the first end 261 of the longitudinal leg 26. Thus, it is possible that the slot 254 can have any extension length in the longitudinal leg 26.

[0132] A further difference of this embodiment of the magnetic levitation device 1 from the embodiments from FIGS. 1 and 6 is that the back iron 28 is designed differently. The back iron 28 is designed as a ring-shaped metal strip 29, which extends from a radially inner starting portion to a radially outer end 292. The strip 29 forms several strip windings 293, which lie flat against each other in the radial direction R. The longitudinal leg 26 is delimited at its first end 261 by an axial end face 265, on which the back iron 28 rests. The back iron 28 forms a circular ring, the radial width of which is equal to the radial width of the end face 265 of the longitudinal leg 26. This means that the radially inner starting portion 291 is flush with the radially inner inner surface 266 of the longitudinal leg 26 in the axial direction A, and the radially outer end 292 is flush with the radially outer outer surface 267 of the longitudinal leg 26 in the axial direction A.

[0133] Among other things, this has the advantage that there is more space within the stator 2, which can be used to install other components therein. In doing so, the stator 2 together with the stator housing can be made smaller and more compact, which increases the flexibility of use of the magnetic levitation device 1.

[0134] A further advantage of such an arrangement of the back iron 28 arises from the arrangement of the strip windings 293 of the tape-wrapped toroidal core strip 29. Due to the fact that the strip windings 293 are arranged perpendicular to the radial direction R, they have an orientation parallel to the path of the magnetic field in the longitudinal legs 26. As a result, the magnetic field from the longitudinal legs 26 enters the back iron 28 in the axial direction A, and thus parallel to the strip windings 293. This means that the magnetic field does not penetrate any of the strip windings 293 in the radial direction R, thereby avoiding eddy current losses.

[0135] Similarly, as already mentioned, here only one concentrated winding 61 is arranged in each case on each longitudinal leg 26 in the third embodiment.

[0136] It goes without saying that all the embodiments with their respective characteristics shown in the description of the drawings can be combined with one another in any way.

[0137] Furthermore, all of the shown embodiments of the coil core 25 can be designed in such a way that the space available for the rotor 3 within the magnetic levitation device 1 is increased. This is achieved by the particular outer shape of the coil core 25.

[0138] In the process, the coil core 25 is divided into an axially lower portion and an axially upper portion, which are arranged adjacent to each other in the axial direction A. The pole pieces 27 are arranged in the axially upper portion. For each coil core 25, the end face 272 of the pole piece 27 has a first radial distance from the axially lower portion of the associated longitudinal leg 26 and a second radial distance from the axially upper portion, the second distance being greater than the first distance. This means that each longitudinal leg 26 is designed such that the axially upper portion is radially displaced outward relative to the axially lower portion, thereby increasing the space available to the rotor 3 between the end faces 272 without risking direct transmission of magnetic flux between the longitudinal leg 26 and the magnetically effective core 31 of the rotor 3. Due to the fact that the axially upper portion is radially displaced outward relative to the axially lower portion, the distance between the longitudinal leg 26 and the end face 272, i.e., the second distance, increases in the region of the axially upper portion. In doing so, the distance between the magnetically effective core 31 and the longitudinal legs 26 of the rotor, particularly in the region of the upper axial portion, also increases.

[0139] Such a coil core 25 as just described is designed similarly to such a coil core illustrated in FIG. 3 of EP-A-4084304.

[0140] FIG. 9 shows a schematic cross-sectional view of one embodiment of the stator housing 21. In the embodiments in FIGS. 1, 6, and 8, this stator housing 21 is not depicted for reasons of a better overview. FIG. 9 is intended only to serve as an illustration to show what the internal encapsulation of the stator 2 required for operation of the magnetic levitation device 1 looks like. For this reason, the other components of the stator 2 are only depicted diagrammatically and should be understood as purely illustrative.

[0141] An embodiment of the stator housing 21 is also possible in which the cup-shaped recess 211 merges into a hole that extends centrally along the central axis of the stator 2 in the axial direction A through the entire stator housing 21 .

[0142] For example, during operation of the magnetic levitation device 1 in areas where chemically aggressive substances are used, it is important that the interior of the stator 2 is safely encapsulated and thus protected from these substances. To ensure that the rotor 3 can still be used, the stator housing 21 has a cup-shaped recess 211 into which the rotor 3 can be inserted.

Claims

1. 1. A magnetic levitation device for contactless magnetic levitation of a rotor (3) having a disk-shaped or ring-shaped magnetically effective core (31), the magnetic levitation device comprising a stator (2) disposed at an axial end of the stator (2) and provided with a cup-shaped recess (211) into which the rotor (3) can be inserted, the stator (2) having a plurality of coil cores (25) each having a longitudinal leg (26) and a magnetic pole piece (27), each longitudinal leg (26) extending from a first end (261) in an axial direction (A) a contact surface (271) disposed at said second end (262); each pole piece (27) extends from said contact surface (271) at least partially in a radial direction (R) from said contact surface (271) to an end face (272) disposed around said cup-shaped recess (211); and at least one concentrated winding (61) disposed on each longitudinal leg (26) and surrounding said respective longitudinal leg (26), A magnetic levitation device, characterized in that each pole piece (27) is made of transverse elements (273) of sheet metal, said transverse elements (273) being stacked in said axial direction (A).

2. 2. The magnetic levitation device of claim 1, wherein each longitudinal leg (26) is made of a longitudinal element (263) of sheet metal, said longitudinal elements (263) being stacked in the circumferential direction of said stator (2).

3. 3. The magnetic levitation device according to claim 1 or 2, wherein the transverse elements (273) and / or the longitudinal elements (263) are made of electrical sheet metal.

4. 4. A magnetic levitation device according to any one of claims 1 to 3, wherein the contact surface (271) is designed in a planar manner and is arranged on the surface of the longitudinal leg (26) perpendicular to the radial direction (R).

5. 5. A magnetic levitation device as claimed in any one of claims 1 to 4, wherein the end surface (272) of the pole piece (27) is designed as a curved surface, and the end surface (272) is designed and arranged coaxially with respect to the cup-shaped recess (211).

6. 6. A magnetic levitation device as claimed in any one of claims 1 to 5, wherein the end surface (272) is designed to be wider in the circumferential direction than the maximum extension of the contact surface (271) in the circumferential direction.

7. 7. The magnetic levitation device of claim 1, wherein the end face (272) has at least one slot (2724) extending in the axial direction (A).

8. 8. The magnetic levitation device of claim 7, wherein the at least one slot (2724) extends from a first axial end (274) of the pole piece (27) to a second axial end (275) of the pole piece (27).

9. 9. A magnetic levitation device as described in claim 7 or 8, wherein the extension (T) of said at least one slot (2724) in said radial direction (R) is shorter than the extension (L) of said pole piece (27) in said radial direction (R).

10. A magnetic levitation device as claimed in any one of claims 7 to 9, wherein several slots (2724) are arranged parallel, or at least approximately parallel, to one another on the end face (272).

11. 11. A magnetic levitation device as claimed in any one of claims 1 to 10, wherein each coil core (25) has a rounded portion (257) at its axial upper end (252) to change the direction of the coil core from the axial direction (A) to the radial direction (R).

12. 12. A magnetic levitation device as claimed in any one of claims 1 to 11, wherein each coil core (25) has a first lateral boundary surface (255) and a second lateral boundary surface (256), and at least one of the first lateral boundary surface (255) and the second lateral boundary surface (256) has at least one slot (254).

13. 13. A magnetic levitation device as claimed in any one of claims 1 to 12, wherein a back iron (28) is arranged at the first end (261) and connects the first ends (261) of all the longitudinal legs (26), the back iron (28) being designed in a ring shape with metal strips (29) extending from a radially inner starting point (291) to a radially outer end (292), the strips forming several strip windings (293) that lie flat and abut against each other with respect to the radial direction (R).

14. 14. The magnetic levitation device of any one of claims 1 to 13, wherein the stator (2) is designed to generate a torque capable of magnetically driving the rotor (3) to rotate about the axial direction (A) without contact.

15. 15. An electromagnetic rotary drive mechanism designed as a temple motor, characterized in that the electromagnetic rotary drive mechanism comprises a magnetic levitation device (1) according to claim 14 and a rotor (3) with a disk-shaped or ring-shaped magnetically effective core (31), the rotor (3) being insertable into a cup-shaped recess (211), the rotor (3) being designed as the rotor (3) of the electromagnetic rotary drive mechanism.

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