Magnetic levitation device and pump unit

Abstract

We provide a magnetic levitation device for non-contact magnetic levitation of a rotor. [Solution] The magnetic levitation device 1 comprises a stator 2 extending in the axial direction A and having a cup-shaped recess into which a rotor 3 can be inserted. The stator has a plurality of coil cores, each of which has connecting legs 26 and pole pieces 27. Each connecting leg extends from a first end 261 to a second end 262, with the first end in contact with a back iron 28. Each pole piece 27 has a second contact surface 271 that contacts the second end 262 of the connecting leg, extends radially R from the second contact surface to the end face, and all end faces are positioned around the cup-shaped recess. A concentrated winding 61 is arranged on each connecting leg, and the winding surrounds each connecting leg, each connecting leg extending diagonally with respect to the axial direction A, so that the second end of each connecting leg is at a smaller distance from the cup-shaped recess in the radial direction R than the first end 261.

Description

[Technical Field]

[0001] The present invention relates to a magnetic levitation device according to the preamble of an independent claim, and to a pump unit comprising such a magnetic levitation device. [Background Art]

[0002] Magnetic levitation devices for contactless magnetic levitation of a rotor are advantageous because they do not require mechanical bearings for the rotor. The rotor is levitated or stabilized by magnetic forces generated by a stator of the magnetic levitation device. Due to the absence of mechanical bearings, such magnetic levitation devices are particularly suitable for pumping devices, mixing devices, centrifugal separation devices or stirring devices. These devices are used when conveying very sensitive substances, such as for example blood pumps, or are used when very high purity is required, for example in the pharmaceutical or biotechnology industries, or are used when conveying abrasive or corrosive substances that would destroy mechanical bearings very quickly, such as for example pumps or mixers for slurries, sulfuric acid, phosphoric acid or other chemical substances in the semiconductor industry.

[0003] In the biotechnology industry, such magnetic levitation devices are used for example in connection with bioreactors, for example in the case of centrifugal pumps for conveying fluid into and out of bioreactors, or in the case of mixing devices for mixing fluid within bioreactors. In the semiconductor industry, such magnetic levitation devices are used not only for conveying corrosive or abrasive substances, but also for example in rotating devices used for rotating wafers.

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

[0005] An advantageous configuration known for magnetic levitation devices is the configuration in a temple structure. Such a magnetic levitation device is illustrated in Figure 1. The reference numerals in Figure 1 are enclosed in quotation marks to clarify that these components belong to the prior art.

[0006] A characteristic feature of the temple structure is that the stator 2' of the magnetic levitation device 1' has multiple coil cores 25', each coil core 25' having a longitudinal leg 26' extending from a first end 261' in the axial direction A' to a second end 262'. In this example, the axial direction A' means the direction defined by the desired axis of rotation of the rotor 3' levitated by the magnetic levitation device 1'. The desired axis of rotation is the axis of rotation that the rotor 3' rotates around when it is in an operating state where the rotor 3' is centered and not tilted relative to the stator 2'. In addition to the longitudinal leg 26', each coil core 25' has a transverse leg 27', also called a pole leg, which in each example is located at the second end 262' of the longitudinal leg and usually extends in an inward radial direction R', which is perpendicular to the axial direction A'. Thus, the transverse leg 27' extends approximately perpendicular to the longitudinal leg 26'. Each coil core 25' is L-shaped, and the lateral legs 27' form short L-shaped legs. In this case, the rotor 3' to be levitated is positioned between the lateral legs 27'.

[0007] The name of this structure comes from the fact that the multiple vertical legs 26' extending in the axial direction A' resemble the pillars of a temple.

[0008] In a configuration illustrated in Figure 1, the stator 3' of the magnetic levitation device 1' has, for example, six coil cores 25', which are arranged in a circular pattern at equal intervals around a cup-shaped recess (not explicitly illustrated in Figure 1), and the rotor 3' may be inserted into the cup-shaped recess. The first ends of the longitudinal legs are connected circumferentially by back irons 28', which typically serve to conduct magnetic flux. The rotor 3' to be levitated comprises a magnetically active core 31', for example, a permanent magnetic disk or a permanent magnetic ring, which is positioned between the radially inward ends of the transverse legs 27' and rotates about an axial direction A' in the operating state, and the rotor 3' levitates magnetically in a non-contact manner relative to the stator 2'.

[0009] In the case of such a magnetic levitation device 1', the rotor's magnetoactive core 31' does not necessarily have to be a permanent magnetic design. Designs are also known in which the rotor's magnetoactive core 31' is designed without permanent magnets, i.e., without permanent magnets. In that case, the rotor's magnetoactive core 31' is, for example, a ferromagnetic design and is made of, for example, iron, nickel-iron, cobalt-iron, silicon-iron, mu-metal, or another ferromagnetic material.

[0010] Furthermore, it is possible to design the rotor's magnetically active core 31' to include both ferromagnetic and permanent magnetic materials. For example, a permanent magnet can be placed or inserted within the ferromagnetic body. Such a design is advantageous, for example, when it is desirable to reduce costs by saving permanent magnetic material in the case of large rotors.

[0011] The vertical legs 26' hold the windings 61' in order to generate the electromagnetic field necessary for the non-contact magnetic levitation of the rotor 3'. The windings 61' are designed such that, for example, concentrated windings 61' are wound around each vertical leg 26', i.e., in each case, the coil axis of each concentrated winding 61' extends in the axial direction A'. In this case, in the temple structure, the coil axis of the concentrated windings 61' extends in the axial direction A', and typically the concentrated windings 61' are not located in the radial plane R' on which the rotor 3' or the rotor's magnetically active core 31' levitates in the operating state.

[0012] It is also possible to design the system so that each vertical leg 26' has exactly one concentrated winding 61'. In other designs, each vertical leg 26' has several concentrated windings 61', for example, exactly two concentrated windings 61'. It is also possible to design the system so that windings 61' are wound around two circumferentially adjacent vertical legs 26', resulting in both adjacent vertical legs 26' being located inside the concentrated winding 61'.

[0013] The aforementioned temple structure enables the proven magnetic levitation device 1' known from prior art, but there is still room for improvement. In the case of magnetic levitation devices 1' in temple structures, it is difficult to design them to be sufficiently compact. The operation of magnetic levitation devices 1' in temple structures requires vertical legs 26' and concentrated windings 61'. However, these also define the spatial extent of the device. Therefore, it is not possible to easily use such magnetic levitation devices 1' in applications where there is little space for them due to spatial constraints, for example. Conversely, this means that magnetic levitation devices 1' in temple structures cannot be designed to be compact enough to operate reliably in some applications, or they can only be designed at great expense.

[0014] The non-compact nature of the magnetic levitation device 1' also leads to the need for large amounts of material to fabricate its individual components. Consequently, the overall weight and cost of device 1' increase, which may make it unsuitable for some application areas.

[0015] Furthermore, designing a magnetic levitation device 1' with more than six coil cores 25' in a temple structure is often difficult. If the size of the rotor 3' or magnetically active core 31' cannot be changed, for example, it is difficult to insert two more coil cores 25' around the cup-shaped recess 211'. Moreover, due to the limited available space, the vertical legs 26' are placed very close to each other, which can lead to stray flux and thus large iron losses. A further problem that can lead to large iron losses is that the structure of the vertical legs 26' creates long magnetic paths. However, these long magnetic paths are undesirable because the resulting losses must ultimately be dissipated in the form of heat, and therefore reduce the efficiency of the magnetic levitation device in the temple structure. [Overview of the project] [Problems that the invention aims to solve]

[0016] Therefore, the object of the present invention is to propose a magnetic levitation device that is more compact and highly efficient for non-contact magnetic levitation of a rotor having a disk-shaped or ring-shaped magnetically active core, based on the prior art.

[0017] Furthermore, an object of the present invention is to propose a pump unit having such a magnetic levitation device.

[0018] The subject matter of the present invention, which satisfies this objective, is characterized by the features of the independent claims. [Means for solving the problem]

[0019] Accordingly, according to the present invention, a magnetic levitation device is proposed for non-contact magnetic levitation of a rotor having a disc-shaped or ring-shaped magnetically active core, the magnetic levitation device comprising a stator that extends axially and has a cup-shaped recess, the cup-shaped recess being located at the axial end of the stator into which the rotor can be inserted. The stator has a plurality of coil cores, each of which has connecting legs and pole pieces, each connecting leg extending from a first end to a second end, the first end of which abuts against a back iron. Each pole piece has a second contact surface that abuts against the second end of the connecting leg, each pole piece extending radially from the second contact surface to an end face, the radial direction being perpendicular to the axial direction. All end faces are located around the cup-shaped recess, and at least one concentrated winding is located on each connecting leg, the winding surrounding each connecting leg. Each connecting leg extends obliquely to the axial direction, so that the second end of each connecting leg is at a smaller radial distance from the cup-shaped recess than the first end.

[0020] In other words, the connecting leg has a range that extends radially inward. That is, the connecting leg is oriented in a direction that is neither parallel nor perpendicular to the axial direction. That is, the axis of the connecting leg makes an angle greater than 0° and less than 90° with respect to the axial direction. The angle is preferably between 20° and 60°. The axis of the connecting leg that makes this angle with respect to the axial direction preferably extends from a first center point of the first contact surface of the connecting leg to a second center point of the second contact surface of the connecting leg, the second contact surface being positioned on the contact surface of the pole piece.

[0021] This configuration of the magnetic levitation device enables the realization of a compact magnetic levitation device. Similarly, it is advantageous that a larger number of coil cores can be arranged around the cup-shaped recess than in the temple motor known from the prior art. This ensures that the coil cores cover a wider area of ​​the rotor surface facing the end faces of the pole pieces in the circumferential direction. Thus, an improvement in the magnetic flux conductivity of the magnetic field is achieved.

[0022] In the context of the present application, the term "cup-shaped recess" is understood to mean a recess similar in shape to a cup. That is, the cup-shaped recess has at least one diameter in the radial direction. The outer contour of the cup-shaped configuration may be designed as a cylinder, a cone, or a combination of the two shapes. The cup-shaped recess can have both a closed base and an open base, or can have no base at all. It goes without saying that the cup-shaped recess can also have smaller shaped portions such as openings or depressions.

[0023] In a preferred embodiment, the back iron connects the first ends of all connecting legs.

[0024] The back iron ensures magnetic flux conductivity in the magnetic levitation device.

[0025] In a preferred embodiment, the back iron is designed as a component.

[0026] In a preferred embodiment, the back iron has a plurality of segments, which are preferably produced in a laminated manner from axially stacked back iron elements.

[0027] The number of segments is preferably 12. However, embodiments with a smaller number, for example 6 or 8, or a larger number, for example 16 or 20, are also possible.

[0028] Segmentation of the back iron is particularly advantageous during manufacturing. The segments, as well as the connecting legs and pole pieces arranged thereon, can be manufactured individually and finally assembled to form the entire magnetic levitation device.

[0029] The laminated configuration of the segments reduces overcurrent loss in the magnetic levitation device.

[0030] Back iron can also be manufactured using a lamination method, rather than being composed of segments, by stacking back iron elements in the axial direction.

[0031] In a preferred embodiment, all segments of the back iron are positioned in contact with each other.

[0032] In a preferred embodiment, all segments of the back iron are arranged in contact with each other without any gaps between them.

[0033] Each segment has a first segment end and a second segment end in the circumferential direction. In a preferred embodiment, the segment has a first shape at the first segment end and a second shape at the second segment end, and the first and second shapes are complementary shapes. In other words, the first shape is the male shape and the second shape is the female shape.

[0034] This means that both shapes are designed such that the end of the first segment can be connected to the end of the second segment of the first adjacent segment in a shape-fitting manner, and the end of the second segment can be connected to the end of the first segment of the second adjacent segment in a shape-fitting manner. Thus, the first and second shapes are designed as two connected geometric shapes. In other words, the first shape is the male shape and the second shape is the female shape.

[0035] According to a preferred embodiment, the first and second shapes have circular, semicircular, or elliptical designs. However, other geometric shapes are also possible.

[0036] These embodiments offer a degree of flexibility when joining individual segments together, resulting in the advantage that, for example, individual segments can be moved relative to each other as needed. This also makes it easier to replace individual segments.

[0037] In a preferred embodiment, the first and second shapes have stepped shapes in the axial direction, and the steps at the end of the first segment and the end of the second segment are complementary to each other.

[0038] In a preferred embodiment, each segment has a bore and / or a curved portion that penetrates the segment axially.

[0039] The bores can serve to secure the magnetic levitation device to a base, such as a housing, using fastening means such as screws or rivets. The location of the bores is one example, and it is understood that they can also be located at other positions on the segment. Curves in the back iron are advantageous, for example, when the magnetic levitation device is installed in a very narrow (tightly mating) housing. These can be used, for example, as feedthroughs for cables, or to better disperse the casting compound so that it flows around the entire stator.

[0040] In a preferred embodiment, the back iron bottom surface and the back iron surface are positioned within a plane perpendicular to the axial direction.

[0041] In a preferred embodiment, the segments form a back iron and a continuous and / or composite ring that is perpendicular to the axial direction A.

[0042] In a preferred embodiment, the back iron has an axial upper surface to which the first end of the connecting leg is positioned. In other words, the connecting leg is positioned on the back iron. That is, the first contact surface at the first end of the connecting leg extends in the radial plane, and the axial upper surface of the back iron is in the same radial plane.

[0043] In a preferred embodiment, the back iron has a radially inner surface, and the first end of the connecting leg is positioned on this radially inner surface. In other words, the connecting leg is positioned on the radially inner surface or surface of the back iron. That is, the first contact surface at the first end of the connecting leg mainly extends in a plane perpendicular to the radial direction and is the first contact surface with respect to the radially inner surface of the back iron.

[0044] In a preferred embodiment, the stator has 12 coil cores, and the rotor has multiple rotor poles, preferably 8 rotor poles, with the rotor poles configured in 4 pole pairs.

[0045] In embodiments where the back iron is not segmented, all 12 coil cores are placed on a single back iron. The number of 12 stator poles should be understood as merely an example, and the number of stator poles may be more or less than 12.

[0046] In embodiments with segmented back irons, this preferably means that there are also 12 segments in the back iron on which 12 coil cores are arranged. In other words, in this example, it is preferable that the coil cores always form a unit together with the segments, and that this unit is arranged circumferentially to form a back iron on which the coil cores are arranged.

[0047] However, it is equally possible to place two or more coil cores on the back iron segments. Therefore, for example in this embodiment, it is also possible to form a stator having 12 coil cores by using six segments, each with two coil cores placed on it.

[0048] In a preferred embodiment, the back iron bottom surface and the back iron surface are each positioned in a plane perpendicular to the axial direction.

[0049] In a preferred embodiment, the segments form a back iron and a continuous and / or composite ring that is perpendicular to the axial direction A.

[0050] The number of coil cores and rotor poles may be less than or more than the aforementioned 12 coil cores or 8 rotor poles. Similarly, the number of coil cores per segment may be more than or less than the aforementioned 2 coil cores.

[0051] In a preferred embodiment, at least one of the concentrated windings has a conical design.

[0052] In this example, the conical winding can be of any type known to those skilled in the art from the prior art, such as a stepped conical winding. Similarly, any winding technique known from the prior art means a technique in which high compactness and high filling density are simultaneously achieved with good productivity through a layered structure. These include, for example, wire cross-sectional configurations such as orthocyclic windings, round wires, flat wires, or rectangular wires, and the positioning of the start and end of the winding. Thus, the winding strands can be routed in series or parallel, and can be twisted together as an option. Corresponding insulating means, such as coil holders and insulating layers, are also obvious.

[0053] Furthermore, it is preferable that at least one concentrated winding has a lower end and an upper end, the lower end facing the first end of the connecting leg and the upper end facing the second end of the connecting leg, and that at least one concentrated winding has a first outer diameter at the lower end and a second outer diameter at the upper end, with the first outer diameter being larger than the second outer diameter.

[0054] This is advantageous because it provides a flat surface for the stator at its axial end. Without a conical configuration of concentrated windings, no flat surface exists because the axial range of at least one concentrated winding is higher than the range of the pole piece surface when viewed axially. In other words, the highest axial point of a concentrated winding must not exceed the highest axial point of a pole piece. These two points can, at most, lie on the same radial plane.

[0055] In other words, the stator housing surrounding the stator has a flat surface at the axial upper end of the stator. To put it another way, the axial upper surface of the stator housing lies within a radial plane. This is advantageous for a magnetic levitation device because it allows for better interaction between the stator and the rotor. The rotor, or magnetoactive core, has a radial center plane that coincides with the radial center plane of the pole pieces. That is, the axial position of the rotor when it is inserted into a cup-shaped recess is defined by the axial position of the pole pieces. The configuration of the magnetic levitation device according to the present invention allows for an axial offset between the pole pieces or pole piece surface and the back iron or back iron surface. As a result of this offset, the rotor is levitated to its maximum extent axially above the axial upper surface of the stator housing, i.e., further axially away from the second end of the stator. This maximum axial levitation of the rotor allows for a more compact rotor configuration, resulting in improved stability of rotor levitation within the stator.

[0056] This is particularly advantageous when the magnetic levitation device is intended to levitate a rotor having at least one blade. Such a rotor is used, for example, in applications such as a fluid pump and / or mixer. In such applications where the rotor has maximum levitation, at least one blade can have a smaller axial range, thereby preventing a force acting strictly upward in the axial direction on the blade or rotor. As a result, the tilt moment is reduced, and good and reliable levitation of the rotor is ensured.

[0057] In the case of centrifuges, rotary filters, or cross-flow fans, it is possible to co-levitate the rotor at both ends using two magnetic levitation devices according to the present invention, or a combination of one magnetic levitation device and another according to the present invention. In these applications as well, the rotor can be advantageously made shorter as a result of the magnetic levitation devices according to the present invention, which further advantageously increases the bending resonance frequency of the rotor and displaces it from the operating frequency range.

[0058] Furthermore, this conical configuration with at least one concentrated winding is advantageous for miniaturizing magnetic levitation devices. As a result, the coil core can be arranged more flexibly. For example, the individual pole pieces and their connecting legs, as well as the windings placed on them, can be positioned closer to each other, thereby ensuring improved magnetic flux conductivity between the stator and rotor.

[0059] In a preferred embodiment, the pole pieces are made from a soft magnetic material.

[0060] In this case, the pole pieces are preferably made from electrolytic metal sheets. By general definition, electrolytic metal sheets are understood to mean soft magnetic materials for magnetic cores. Soft magnetic materials are usually referred to as materials with low coercive field strength. Coercive field strength is the magnetic field strength required to demagnetize a material. In the context of this application, soft magnetic materials are understood to mean materials with a coercive field strength of less than 2,000 A / m, or more precisely, a coercive field strength of magnetic polarization. Further preferred soft magnetic materials are, for example, ferromagnetic or ferrimagnetic materials, i.e., iron, nickel-iron, cobalt-iron, silicon-iron, or mu-metals.

[0061] Similarly, connecting legs and back irons can also be fabricated from soft magnetic materials.

[0062] In a preferred embodiment, the pole pieces are manufactured by stacking pole elements, which are stacked in the axial direction.

[0063] Furthermore, each connecting leg is preferably manufactured using a stacking method from elements, and the elements are preferably stacked in the circumferential direction of the stator.

[0064] One of the advantages of a laminated structure is that it can reliably reduce eddy current losses in each component (back iron, connecting legs, pole pieces).

[0065] Because the distance between adjacent pole pieces, especially at their ends facing the cup-shaped recesses, is particularly small, most of the eddy current losses occur in the pole pieces. The magnetic field is initially generated radially in the pole piece. Eddy currents are effectively reduced by stacking the elements of each component. The magnetic field of two adjacent pole pieces in the circumferential direction of the stator also originates from there in the circumferential direction. Therefore, the stacking of each element must be selected so that it is also possible to effectively prevent circumferential overcurrents. In the case of pole pieces, this is ideally possible by stacking the pole elements axially. Similarly, as an alternative, pole pieces can be made from soft magnetic composite (SMC) material. This guarantees a similar effect. Overall, these embodiments lead to a significant reduction in eddy current losses. This brings about an even more important advantage. The magnetic field flowing circumferentially from the pole piece of the first coil core to the adjacent pole piece of the second coil core flows parallel to the axially stacked pole elements and therefore does not produce eddy current losses, so the end faces of the pole pieces can be positioned remarkably close to each other in the circumferential direction. Therefore, for example, passive stiffness and active levitation can be improved, and / or a more compact stator configuration can be achieved.

[0066] By changing the orientation of the stacked configuration between individual components (back iron, connecting legs, pole pieces), we can similarly ensure a further reduction in eddy current losses across the entire magnetic levitation device.

[0067] In a preferred embodiment, the back iron elements are stacked axially (i.e., axially stacked), in which case the connecting legs positioned on the back iron have circumferentially stacked elements, and the pole pieces positioned above them have axially stacked pole elements. This change in arrangement and orientation ensures that losses in the magnetic levitation device are reduced.

[0068] Elements with connecting legs stacked circumferentially have the advantage of lower losses and reduced magnetoresistance compared to elements with connecting legs stacked axially. This is because, in the case of elements stacked circumferentially, the magnetic field does not need to pass through the stacking plane in the axial direction. Conversely, when connecting legs are stacked axially, the magnetic field must flow axially through the boundary between adjacent stacking planes, resulting in losses and increased magnetoresistance.

[0069] Furthermore, the pole pieces and / or connecting legs can also be fabricated from powder composite materials, particularly soft magnetic powder composite materials. In this case, these materials, called "soft magnetic composites (SMC)" in English, can be high-purity iron powder with a specific surface coating. In this case, the specific surface coating is electrically insulating. SMCs are primarily known for their applications in conducting high-frequency magnetic fields (frequency >> 1 kHz). However, their applications at lower frequencies are not known to date. Lower frequencies refer to frequencies below 65 Hz.

[0070] A further advantage of soft magnetic powder composites is their excellent three-dimensional flux conductivity, high electrical resistance and high permeability, and therefore virtually no eddy current losses. Specifically, this three-dimensional flux conductivity ensures that soft magnetic powder composites are suitable for use in pole pieces and / or connecting legs without generating high eddy current losses during the process.

[0071] Because soft magnetic powder composites have relatively high hysteresis losses, in some embodiments, soft magnetic powder composites are used to fabricate pole pieces and / or connecting legs. As a result, a balance is found between reducing eddy current losses in areas where eddy current losses are particularly large and avoiding undesirable effects of the powder composite on the magnetic circuit.

[0072] The attachment of the pole pieces to the connecting legs and the attachment of the connecting legs to the back iron can be carried out by several possible types of joints. These include, among others, pressure-fit type joints such as clamps or crimps, shape-fit type joints such as screw-ins or push-ins, or material-bonding connections such as adhesive bonding or welding. Similarly, it is also possible to create connections via tongue-and-groove connections and / or plug connections, such as pin, prong, or dovetail joints. In preferred embodiments, material-bonding type joints are carried out by bonding. This has the advantage of not causing excessive stress on the powder composite material compared to clamps or screw-ins. In addition, press-fit and shape-fit type joints have the advantage of being less susceptible to defects resulting from, for example, aging or defects in adhesive bonding.

[0073] In a preferred embodiment, the end face of the pole piece is designed as a curved surface. Here, it is particularly preferred that the curve or roundness of the end face is designed to be coaxial with the cup-shaped recess. In other words, the end face of the pole piece is a segment of a cylindrical surface, the central axis of this cylinder coincides with the central axis of the cup-shaped recess, the radius of this cylinder is greater than the radius of the cup-shaped recess, and as a result the end face does not protrude into the cup-shaped recess.

[0074] In a preferred embodiment, the end face is designed to be wider in the circumferential direction than the maximum circumferential extent of the contact surface. 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 segment in the radial plane of the cylindrical surface is longer than the length of one of the circumferentially extending edges of the contact surface.

[0075] Widening the end face in the circumferential direction in this way has the advantage of promoting magnetic functionality. For example, passive stiffness and active levitation can be improved.

[0076] In a more preferred embodiment, the end face is designed to be narrower in the circumferential direction than the maximum circumferential extent of the contact surface. This means that one of the two circumferentially extending edges of the end face is shorter than one of the circumferentially extending edges of the contact surface.

[0077] In a preferred embodiment, the end face has a shape transition, preferably a rounded or stepped, at the edge that constitutes the transition to the pole piece surface. In other words, the edge located at the axial upper end of the end face of the pole piece, and similarly representing the radially inner edge of the pole piece surface, has a shape transition. On the other hand, the shape transition can be understood as meaning that the transition from the end face to the pole piece surface has a radius at the edge. It can also be said that the edge is missing. If the pole piece is constructed in a stacked manner from pole elements stacked in the axial direction, the pole piece can similarly have a shape transition. In this case, the shape transition can also be understood as meaning that, in addition to the shape transition described above, at least one of the pole elements located at the axial upper end of the pole piece has a smaller radial range than the other pole elements. In other words, this at least one pole element is set back relative to the other pole elements when viewed radially from the rotor, i.e., it is further from the rotor than the other pole elements.

[0078] According to a preferred embodiment, the end face has at least one slot extending in the axial direction. In other words, at least one slot can extend in the axial direction for any length on the end face.

[0079] Furthermore, it is preferable that some of the slots are arranged parallel or nearly parallel to each other at the end face.

[0080] Arranging multiple slots parallel to each other has the advantage that the slots are also parallel to, or at least nearly parallel to, the path of the magnetic field, and as a result the slots do not block the magnetic field.

[0081] Furthermore, it is preferable that at least one slot extends from the surface of the pole piece to the bottom surface of the pole piece. Therefore, this range represents the maximum possible axial range of the slot at the end face.

[0082] In a possible embodiment where the end face has two or more slots, one slot may extend axially from the bottom surface of the pole piece, and a second slot may extend axially from the surface of the pole piece opposite the first slot. In this example, the axial extent of each of the two slots may be less than 50% of the axial extent of the end face. In other words, the end face has two slots that do not touch each other in the center of the end face, and therefore at least one pole element of the pole piece is located there, and this pole element is not captured by the slot.

[0083] Introducing at least one slot on the end face of the pole piece provides electrical insulation. That is, at least one slot ensures that the path of eddy currents within the pole element is interrupted, and therefore sealed. Eddy currents generated by the axially generated magnetic field from the pole element can thus be prevented or reduced. As a result, only a small amount of eddy current remains within the pole piece, and the overall eddy current loss of the pole piece is significantly reduced.

[0084] Slots can be fabricated in various ways. These include, among other things, mechanical methods such as milling, punching, or cutting, and cutting methods may also include the use of laser cutting and / or water jet cutting and / or wire electrical discharge machining (EDM).

[0085] In a particularly preferred embodiment, the stator of the magnetic levitation device is designed to generate torque, which allows the rotor to be magnetically driven in a non-contact manner for rotation around the axial direction.

[0086] Here, the stator is configured as a bearing and drive stator, being both an electrically driven stator and a magnetically levitated stator. The electric windings of the stator can generate a rotating magnetic field, which on the one hand provides the rotor with torque that causes rotation around a desired axis of rotation, and on the other hand provides the rotor with an arbitrarily adjustable lateral force so that the radial position of the rotor can be actively controlled or adjusted.

[0087] In particular, with respect to embodiments in which the magnetic levitation device is designed to generate torque, a configuration with a wider end face is advantageous because it consequently enhances magnetic functionality. For example, it may be possible to generate a large torque or improve passive stiffness or active axial force.

[0088] In a preferred embodiment, the magnetic levitation device comprises several sensors for determining the rotor position and / or the rotor rotation angle. Preferably, the sensors are positioned between every other stator pole. Sensors may also be positioned at other locations on the magnetic levitation device. The number of sensors is preferably 4 to 8, but the magnetic levitation device may have more or fewer sensors.

[0089] According to a preferred embodiment, the magnetic levitation device is designed as an electromagnetic rotary drive, or as a mixing device, or as a centrifuge, or as a cross-flow fan, or as a rotary filter, or as a viscometer.

[0090] In other words, the magnetic levitation device according to the present invention can be configured or used for various fluid transport units as described above. In this example, the fluid transport unit comprises a rotor, which supplies energy to the fluid by rotation and moves the fluid.

[0091] Furthermore, the present invention proposes an electromagnetic rotary drive, also called a coupling motor, which comprises a magnetic levitation device according to the present invention and a rotor having a disk-shaped or ring-shaped magnetically active core, the rotor of which can be inserted into a cup-shaped recess, and the rotor is designed as a rotor for an electromagnetic rotary drive.

[0092] Such electromagnetic rotary drives are also known as "bearing-free motors." In this context, the term "bearing-free motor" refers to an electromagnetic rotary drive in which there are no separate magnetic bearings, and the rotor is completely magnetically levitated relative to the stator.

[0093] Furthermore, the present invention proposes a pump unit for a magnetic levitation device according to the present invention, the pump unit comprising a rotor, and the pump unit comprising a pump housing having an inlet and an outlet for the fluid to be conveyed. The rotor is located within the pump housing and has a plurality of blades for conveying the fluid. The pump housing partitions the pump chamber and has a cover portion and a base portion. The base portion has a cylindrical or conical cup for receiving the rotor, which can be inserted into a cup-shaped recess of a stator.

[0094] Further advantageous means and embodiments of the present invention will become apparent from the dependent claims.

[0095] The present invention will be described in more detail below with reference to exemplary embodiments and drawings. [Brief explanation of the drawing]

[0096] [Figure 1] This is a perspective view of a magnetic levitation device using a temple structure known from prior art. [Figure 2] This is a perspective view of a first exemplary embodiment of the magnetic levitation device according to the present invention. [Figure 3] Figure 2 is a schematic cross-sectional view of an exemplary embodiment. [Figure 4] This is a schematic cross-sectional view of an exemplary embodiment from Figure 2, which has a stator housing. [Figure 5] This is a perspective view of the segment with the coil core arranged and the concentrated winding from Figure 2. [Figure 6] This is a schematic cross-sectional view of the segment in which the coil core is located and the concentrated winding from Figure 5. [Figure 7] This is a perspective view of a second embodiment of a segment in which a coil core is arranged. [Figure 8] This is a perspective view of a third embodiment of a segment in which a coil core is arranged. [Figure 9] This is a plan view of a second exemplary embodiment of the magnetic levitation device according to the present invention. [Figure 10] Figure 9 shows a schematic cross-sectional view of a second exemplary embodiment. [Figure 11] A perspective view of a further embodiment of the polar segment. [Figure 12] This is a cross-sectional view showing a pump unit inserted into a magnetic levitation device according to the present invention. [Figure 13] This is a perspective cross-sectional view showing a mixing unit inserted into a magnetic levitation device according to the present invention. [Figure 14] This is a schematic diagram of the wiring for controlling and adjusting the magnetic levitation device according to the present invention. [Modes for carrying out the invention]

[0097] As previously described, Figure 1 shows a perspective view of a magnetic levitation device 1' with a temple structure known from the prior art.

[0098] Figure 2 shows a perspective view of a first exemplary embodiment of a magnetic levitation device according to the present invention, and is collectively indicated by reference numeral 1. Figure 3 shows a schematic cross-sectional view of the first exemplary embodiment from Figure 2. The magnetic levitation device 1 is designed for non-contact magnetic levitation of a rotor 3 having a disk-shaped or ring-shaped magnetically active core 31. The magnetic levitation device 1 comprises a stator 2. The stator 2 typically comprises a stator housing 21 (Figure 4), which is not shown in Figure 2 for clarity. Thus, Figure 4 shows a schematic cross-sectional view of an exemplary embodiment from Figure 2 having the stator housing 21. Figure 4 is intended only to show the internal sealing of the stator 2 necessary for the operation of the magnetic levitation device 1. For this reason, other components of the stator 2 are shown schematicly only and should be understood as merely illustrative.

[0099] For example, during the operation of the magnetic levitation device 1 in an area where chemically corrosive substances are used, it is important that the inside of the stator 2 is reliably sealed and thus protected from these substances. Nevertheless, so that a rotor 3 may be used, the stator housing 21 has a cup-shaped recess 211 at its axial end into which the rotor 3 can be inserted.

[0100] The portion of the stator housing 21 adjacent to the concentrated winding 61 at the upper axial end AE1 of the stator 2, and the portion of the stator housing 21 facing the cup-shaped recess 211, are manufactured from a low-loss material, particularly preferably from a non-conductive or slightly conductive material such as plastic. The other portions of the stator housing 21 are preferably manufactured from a material with good thermal conductivity, such as aluminum.

[0101] The stator housing 21 is preferably hermetically sealed, or, depending on the design of the housing 21, is already designed to be hermetically sealed during manufacturing so that no substances harmful to the inside of the magnetic levitation device 1 can come into contact with the stator 2. Exemplary embodiments may also include the housing 21 having a chemically durable or resistant coating, such as one or more polymer coatings.

[0102] The stator housing 21 may also be provided with a cooling device to cool the magnetic levitation device 1, particularly the stator 2, and thus protect the stator 2 from overheating.

[0103] The stator housing 21 can be used to fix the stator 2 in a predetermined position on one side, and to fill on the other side with a cast compound that contributes to temperature control of the stator 2 or the magnetic levitation device 1.

[0104] The electronic equipment for operating the magnetic levitation device 1 may be located inside, i.e., inside the stator housing 21, or it may be located entirely or partially outside, for example, in separate electronic components. The electronic components may be located away from the magnetic levitation device 1 and connected via one or more cables, or they may be mounted on the outer wall of the housing 21, for example. In particular, the electronic equipment may include not only all components for rotor levitation and driving, but also components for, for example, sensor technology.

[0105] The rotor 3 is designed to rotate around a desired axis of rotation. This desired axis of rotation defines the axial direction A. The central axis of the stator 2, which extends in the axial direction A, typically corresponds to the desired axis of rotation. In this example, the desired axis of rotation refers to the axis around which the rotor 3 rotates when it is in an operating state where it is in a central and non-tilted position relative to the stator 2, as shown in Figure 2.

[0106] The stator 2 has a plurality of coil cores 25, in this case 12 coil cores, each coil core having connecting legs 26 and pole pieces 27. Each connecting leg 26 extends from a first end 261 to a second end 262. The first end 261 abuts against the back iron 28. In this exemplary embodiment, the back iron 28 has several segments 281, in this case 12 segments 281, an axial upper surface 281, and a radial inner surface 283. The number of segments 281 in this exemplary embodiment is for illustrative purposes only. The back iron 28 may also contain more or fewer segments 281 than 12. In a preferred exemplary embodiment, the number of coil cores 25 is equal to the number of segments 281, since a coil core 25 is always located on each segment 281.

[0107] In this first exemplary embodiment, the back iron 28, or segment 281, is manufactured in a laminated manner from back iron elements 286 stacked in the axial direction A.

[0108] In this first exemplary embodiment, the first end 261 of the connecting leg 26 is positioned on the radially inner surface 283. Embodiments are also possible in which the first end 261 of the connecting leg 26 is positioned on the axially upper surface 281 (Figures 9 and 10).

[0109] Each pole piece 27 has a second contact surface 271 that abuts against the second end 262 of the connecting leg 26. Each pole piece 27 extends radially R perpendicular to the axial direction A from the second contact surface 271 to the end face 272, with all end faces 272 positioned around the cup-shaped recess 211.

[0110] There is an intermediate space between adjacent pole pieces 27, and at least one sensor is introduced within at least one intermediate space. However, some intermediate spaces may also have at least one sensor, and as a result, in some exemplary embodiments, at least one sensor is placed within each intermediate space. At least one sensor is provided to measure rotor characteristics, such as rotor position, and / or stator characteristics, such as temperature. For this purpose, the following types of sensors, in particular Hall sensors, eddy current sensors, optical sensors, capacitive sensors, and temperature sensors can be used. Combinations of the aforementioned sensors may also be provided. In all the exemplary embodiments shown, the sensors are not illustrated for clarity.

[0111] In the exemplary embodiment shown in Figure 2, the end faces 272 of each pole piece 27 are designed as curved surfaces. The curvature of the end faces 272 is designed to be coaxial with the cup-shaped recess 211. In other words, the end faces 272 of the pole pieces 27 are segments of a cylindrical surface, the central axis of this cylinder coincides with the central axis of the cup-shaped recess 211, and the radius of this cylinder is greater than the radius of the cup-shaped recess 211, so that the end faces 272 do not protrude into the cup-shaped recess 211. However, exemplary embodiments in which the end faces 272 are not curvatured are also possible.

[0112] Furthermore, in the first exemplary embodiment, the end face 272 is designed to be wider in the circumferential direction than the maximum circumferential range of the contact surface 271. This means that one of the two circumferentially extending edges 2721, 2722 (Figure 5) of the end face 272 is longer than one of the circumferentially extending edges 2711, 2712 (Figure 5) of the contact surface 271. If the end face 272 is designed as a curved surface, the length of one of the arcs of the segment in the radial plane of the cylindrical surface is longer than the length of one of the circumferentially extending edges 2711, 2712 (Figure 5) of the contact surface 271.

[0113] Widening the end face 272 in the circumferential direction in this way is advantageous because it promotes magnetic functionality. For example, it can improve passive rigidity and active levitation.

[0114] However, exemplary embodiments are also possible in which the end face 272 is designed to have the same width as the maximum extent of the contact surface 271 in the circumferential direction.

[0115] The back iron segments 281 are arranged adjacent to each other on a circular line, so that when the rotor 3 is inserted into the cup-shaped recess 211, the pole pieces 27 or their end faces 272 connected to the segments 281 via the connecting legs 26 surround the magnetically active core 31 of the rotor 3.

[0116] Each connecting leg 26 extends diagonally with respect to the axial direction A, and as a result, the second end 262 of each connecting leg 26 is located at a smaller distance from the cup-shaped recess 211 in the radial direction R than the first end 261.

[0117] In other words, the connecting leg 26 has a range that extends radially inward. That is, the connecting leg 26 is oriented in a direction that is neither parallel nor perpendicular to the axial direction A. That is, the axis AV of the connecting leg (Figure 6) makes an angle α with the axial direction A that is greater than 0° and less than 90°. The angle α is preferably between 30° and 80°, and particularly preferably between 45° and 75°. The axis AV of the connecting leg 26 that makes an angle α with respect to the axial direction A preferably extends from the first center point of the first contact surface 263 of the connecting leg 26 to the second center point of the second contact surface 265 (Figure 6) of the connecting leg 26, and the second contact surface 265 is positioned on the contact surface 271 of the pole piece 27.

[0118] Furthermore, this means that the second end 262 of the connecting leg 26 is at a smaller distance from the cup-shaped recess 211 than the first end 261.

[0119] Here, comparing the prior art in Figure 1 with the first exemplary embodiment of the magnetic levitation device 1 in Figure 2, it is immediately apparent that the magnetic levitation device 1 is configured to be much more compact, particularly with respect to the axial direction A. A further advantage is that in the magnetic levitation device 1 according to the present invention, many more coil cores 25 can be arranged around the cup-shaped recess 211. This ensures that the coil cores 25 cover a wider area of ​​the rotor 3 facing the end face 272 of the pole piece 27 in the circumferential direction. Thus, an improvement in the magnetic flux conductivity of the magnetic field is achieved.

[0120] At least one centralized winding 61 is located on each connecting leg 26, and this winding surrounds each connecting leg 26.

[0121] The concentrated winding 61 plays a role in generating an electromagnetic field, which allows the rotor 3 to magnetically levitate within the cup-shaped recess 211 (Figure 4) in a non-contact manner.

[0122] In this exemplary embodiment, the concentrated winding 61 has a conical design.

[0123] For better understanding, Figure 5 shows a perspective view, and Figure 6 shows a schematic cross-sectional view of the segment 281 on which the coil core 25 is located and the concentrated winding 61 of the first exemplary embodiment from Figure 2. In other words, a concentrated winding 61 of a conical design is understood to mean a winding 61 in which at least one concentrated winding 61 has a first outer diameter WA1 at a first radial end 611 and a second outer diameter WA2 at a second radial end 612, and the first outer diameter WA1 is greater than the second outer diameter WA2.

[0124] This is advantageous because a flat surface of the stator 2 is obtained at the axial end of the stator 2. If there is no conical configuration of the concentrated winding 61, the axial A range of at least one concentrated winding 61 will be higher than the range of the pole piece surface 273 of the pole piece 27 (Figures 5 and 6) when viewed from the axial A, so no flat surface exists. In other words, the highest point of the axial A of the concentrated winding 61 must not exceed the highest point of the axial A of the pole piece 27. These two points can at most lie on the same radial plane.

[0125] In other words, the stator housing 21 surrounding the stator 2 has a flat surface at the axial upper end of the stator 2. To put it another way, the axial upper surface 212 (Figure 4) of the stator housing 21 lies within the radial plane. This is advantageous for the magnetic levitation device 1 because it allows for better interaction between the stator 2 and the rotor 3. The rotor 3, or magnetoactive core 31, has a radial center plane RM1 that coincides with the radial center plane RM2 of the pole pieces 27 in the stationary position. This ensures that the levitation of the rotor 3 is well and reliably guaranteed.

[0126] Furthermore, this conical configuration of at least one concentrated winding 61 is advantageous for miniaturizing the magnetic levitation device. As a result, the coil core 25 can be arranged more flexibly. For example, the individual pole pieces 27 and their connecting legs 26, as well as the windings 61 placed on them, can be positioned closer to each other, thereby ensuring improved magnetic flux conductivity between the stator 2 and the rotor 3.

[0127] In this exemplary embodiment of the magnetic levitation device 1, all components (back iron 28 or segment 281, connecting legs 26, and pole pieces 27) are constructed in a stacked manner from elements (264, 275, 286).

[0128] Here, segment 281 is manufactured in a stacking manner from back iron elements 286, which are stacked in the axial direction A. Connecting legs 26 are manufactured in a stacking manner from elements 264, which are stacked in the circumferential direction of the stator 2. Pole pieces 27 are manufactured in a stacking manner from pole elements 275, which are stacked in the axial direction A.

[0129] In all exemplary embodiments and figures, the number of elements (264, 275, 286) should be understood as illustrative only. The actual number may be greater or less than the number shown.

[0130] By changing the orientation of the stacked configuration between individual components (26, 27, 28, or 281), a reduction in eddy current losses across the entire magnetic levitation device is ensured.

[0131] The elements 264 of the connecting legs 26 stacked in the circumferential direction have the advantage of lower losses and reduced magnetic resistance compared to the case where the elements 264 of the connecting legs 26 are stacked in the axial direction A. This is because, in the case of elements 264 stacked in the circumferential direction, the magnetic field does not need to pass through the stacking planes in the axial direction A, and insulation between the stacking planes is not required in each case. Conversely, when the connecting legs 26 are stacked in the axial direction A, the magnetic field needs to flow in the axial direction A through the boundary between adjacent stacking planes, resulting in losses and increased magnetic resistance.

[0132] The stacking orientation of each element (264, 275, 286) is based on this exemplary embodiment. It is also possible to have different stacking orientations for each element (264, 275, 286) for all components (26, 27, 28, or 281). However, it is preferable that the orientation changes at the transition from one component (26, 27, 28, or 281) to the component (26, 27, 28, or 281) placed on top of it.

[0133] One of the advantages of a laminated configuration is that its design ensures a reduction in eddy current losses in each component (26, 27, 28, or 281).

[0134] Because the distance between adjacent pole pieces 27, especially the distance at their ends facing the cup-shaped recess 211, is particularly small, most of the eddy current loss occurs in the pole pieces 27. The magnetic field is initially generated radially A in the pole pieces 27. Eddy currents are effectively reduced by stacking the elements of each component (26, 27, 28). The magnetic fields of two circumferentially adjacent pole pieces 27 of the stator 2 also originate from them circumferentially. The stacking of each element (264, 275, 286) must be selected so as to effectively prevent the generation of magnetic fields and associated eddy currents in the circumferential direction. In the case of pole pieces 27, this is ideally achieved by stacking the pole elements 275 axially A. Similarly, as an alternative, the pole pieces 27 can be made from a soft magnetic composite (SMC). This guarantees a similar effect. Overall, these embodiments lead to a significant reduction in eddy current loss. As a result, as can be seen in Figure 2, the pole pieces 27 can be positioned much closer to each other in the circumferential direction of the stator 2, and thus, compared to the temple motor in Figure 1, it becomes possible to arrange several coil cores 25, in this case 12 coil cores 25.

[0135] In a preferred embodiment, the pole pieces 27 are made from a soft magnetic material. In this example, the pole pieces 27 and / or segments 281 and / or connecting legs 26 are preferably made from electrometallic sheet metal. The definition of electrometallic sheet metal has already been explained in the previous section. Similarly, mu-metal can be used to fabricate elements 264, 275, and 286.

[0136] Soft magnetic materials more suitable for the coil core 25 and back iron 28 are, for example, ferromagnetic or ferrimagnetic materials, i.e., iron, nickel iron, cobalt iron, silicon iron, or mu-metal.

[0137] In other exemplary embodiments, the pole pieces 27 and / or connecting legs 26 may be made from powder composite materials, particularly soft magnetic powder composite materials (SMC). The definition and advantages of this material have already been described in the previous section.

[0138] In a particularly preferred configuration, the stator 2 is designed to exert torque on the rotor 3 or its magnetically active core 31, in addition to providing non-contact magnetic levitation for the rotor 3, thereby driving the rotor 3 to rotate around a desired axis of rotation. That is, in this preferred embodiment, the rotor 3 can be driven to rotate around the axial direction A.

[0139] As already mentioned, widening the end face 272 in the circumferential direction has the advantage of consequently enhancing magnetic functionality. For example, passive stiffness and active levitation force can be improved. In embodiments in which the magnetic levitation device 1 is designed to generate torque, there is an additional advantage of being able to generate a larger torque.

[0140] Therefore, in this configuration, the concentrated winding 61 generates an electromagnetic rotating magnetic field, and this electromagnetic rotating magnetic field allows the rotor 3 to be magnetically levitated relative to the stator 2 in a non-contact manner, and at the same time, to be driven in a non-contact manner for rotation around the axial direction A.

[0141] The rotor 3 comprises a magnetotactic core 31 having a ring-shaped or disk-shaped configuration. According to the example in Figure 3, the magnetotactic core 31 is designed as a ring, defining a magnetic center plane. Several individual magnets 311 (Figure 2) are arranged on the magnetotactic core. This is a so-called quad-pole rotor 3. Needless to say, in other exemplary embodiments, rotors 3 with a number of pole pairs other than quad-pole, such as a unipolar rotor 3, may be used.

[0142] In the exemplary embodiment of the four-pole rotor 3 shown herein, the pole pieces 27 are preferably designed in a stacked configuration where they are stacked axially. When the magnetic levitation device 1 is operating, and the switching between the individual magnets 311 of the rotor 3 occurs at a specific pole piece 27, i.e., as shown in the detailed diagram AS marked in Figure 2, the magnetic field enters the pole piece 27 at a first point and is generated again from the same pole piece 27 at a second point where it has been displaced circumferentially. This magnetic flux conduction is possible with low loss only when the pole pieces 27 are stacked axially. A pole element 275 stacked circumferentially would, in this case, be working against the path of the magnetic field during pole switching, leading to significant losses.

[0143] When a soft magnetic material (SMC) is used as the material for the pole pieces 27, the same advantages as those described above can be obtained. Similarly, SMC is also very suitable for use in the 4-pole pair rotor 3.

[0144] Alternatively, the magnetically active core 31 may also be designed as a disk. In principle, for a disk-shaped or ring-shaped magnetically active core 31, the magnetic center plane is the geometric center plane perpendicular to the axial direction A of the magnetically active core 31 of the rotor 3. In operation, the magnetically active core 31 levitates within a radial plane perpendicular to the axial direction A.

[0145] For the sake of understanding the present invention, only the magnetically active core 31 of the rotor 3 is shown in Figure 2. Needless to say, the rotor 3 may also include further components such as a casing or capsule made of, for example, preferably plastic, or metal, or metal alloy, or ceramic or ceramic material. Furthermore, the rotor 3 may also include blades for mixing, stirring, or pumping fluid or other components.

[0146] When the rotor 3 is inserted into the cup-shaped recess 211 (Figure 4), the rotor 3, in particular the magnetically active core 31 of the rotor 3, is surrounded by the end faces 272 located radially outward from the pole pieces 27 of the coil core 25 of the stator 2.

[0147] 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.

[0148] To generate the electromagnetic field necessary for the magnetic levitation of the rotor 3, and optionally to generate torque in the rotor 3, the connecting legs 26 hold the windings designed as a concentrated winding 61.

[0149] These concentrated windings 61 generate an electromagnetic rotating magnetic field that, in operation, can exert a radially adjustable lateral force on the rotor 3, thereby allowing the radial position of the rotor 3, i.e., the position of the rotor 3 in the radial plane perpendicular to the axial direction A, to be actively controlled or adjusted. Optionally, these electromagnetic rotating magnetic fields additionally impart torque to the rotor 3. The tilt of the rotor 3 can be passively stabilized by ring-shaped or disc-shaped embodiments of the rotor 3. The diameter of the magnetoactive core 31 of the rotor 3 is preferably at least twice the core height of the magnetoactive core 31, where the core height specifies the range of the magnetoactive core in the axial direction A.

[0150] The "magnetically active core 31" of the rotor 3 refers to the region of the rotor 3 that magnetically interacts with the stator 2 for the generation of magnetic levitation force and, optionally, for torque formation.

[0151] As already mentioned, in this exemplary embodiment, the magnetically active core 31 has a ring-shaped configuration and has several individual magnets 311 arranged on the magnetically active core 31. However, exemplary embodiments are also possible in which the magnetically active core 31 does not have individual magnets 311 arranged on it. In that case, the magnetically active core 31 can be made entirely of a permanent magnetic material, and as a result, the magnetically active core 31 becomes a permanent magnet. The magnetically active core 31 is magnetized, for example, in the radial direction.

[0152] Permanent magnets are also commonly called hard magnetic materials, i.e., ferromagnetic or ferrimagnetic materials, that have high coercivity. Coercivity is the magnetic field strength required to demagnetize a material. In the context of this application, a permanent magnet is understood to mean a substance or material having a coercivity greater than 10,000 A / m, or more precisely, a coercivity of magnetic polarization.

[0153] Preferably, the stator 2 and rotor 3 have a predetermined combination of poles. The number of poles of the stator 2 corresponds to the number of stator poles 25, and the number of poles of the rotor 3 corresponds to the number of magnetic poles, in particular the number of permanent magnets. Preferred combinations of stator poles and magnetic poles are given by the following number of pairs in particular. [Table 1]

[0154] Embodiments are also possible in which the magnetically active core 31 is designed without permanent magnets, i.e., without permanent magnets. In that case, the rotor 3 is designed, for example, as a magnetoresistive rotor. In that case, the magnetically active core 31 of the rotor 3 is made of, for example, a soft magnetic material. Suitable soft magnetic materials for the magnetically active core 31 are, for example, ferromagnetic or ferrimagnetic materials, i.e., iron, nickel-iron, cobalt-iron, silicon-iron, and mu-metal.

[0155] Furthermore, embodiments are also possible in which the magnetically active core 31 of the rotor 3 includes both a ferromagnetic material and a permanent magnetic material. For example, a permanent magnet can be placed or inserted into the ferromagnetic body. Such embodiments are advantageous, for example, when it is desirable to reduce costs by saving permanent magnetic material in the case of a large rotor.

[0156] It is also possible to implement a design in which the rotor is constructed according to the principle of a squirrel-cage rotor.

[0157] In contrast, the stator 2 does not contain permanent magnets. In the context of this application, this statement that the stator 2 is designed "without permanent magnets" is intended to be understood as meaning that the stator 2 does not have permanent magnets that substantially contribute to the driving magnetic field for driving the rotation of the rotor 3 or for generating the magnetic levitation force of the rotor 3. Therefore, the magnetic flux generated by the stator 2 for driving and levitating the rotor 3 does not consist of permanent magnetic excitation flux.

[0158] Naturally, the rotor 3 and / or stator 2 may also be equipped with other magnets or permanent magnets, for example, in sensors that serve to detect the angular position of the rotor, or sensors that serve purposes unrelated to the generation of magnetic flux for driving and the levitation of the rotor 3.

[0159] Therefore, the statement "does not contain permanent magnets" relates only to the generation of magnetic flux for driving and the levitation of the rotor 3 by the stator 2. In other words, the stator 2 does not have permanent magnets that contribute to the magnetic flux that magnetically drives and levitates the rotor 3.

[0160] However, while it is possible for the magnetic flux for driving and levitating the rotor 3 to be a permanent magnetic flux, in that case, this permanent magnetic flux is generated solely by the rotor 3 itself. This applies when the rotor 3 itself is equipped with a permanent magnet.

[0161] During the operation of the magnetic levitation device 1, the magnetoactive core 31 of the rotor 3 interacts with the stator 2 in such a manner that the rotor 3 can levitate magnetically relative to the stator 2 in a non-contact manner, and preferably, can also rotate magnetically about the axial direction A in a non-contact manner. In this example, it is particularly advantageous that the same winding 61 used to provide magnetic levitation to the rotor 3 also plays a role in generating torque in the rotor 3. Preferably, in this case, the three degrees of freedom of the rotor 3, namely its position in the radial plane and its rotation, can be actively adjusted. With respect to its axial deflection from the radial plane in the axial direction A, the magnetoactive core 31 of the rotor 3 is passively stabilized magnetically, i.e., in a non-operational manner, by magnetoresistive force. The magnetoactive core 31 of the rotor 3 is also passively stabilized magnetically with respect to the remaining two degrees of freedom, namely its inclination with respect to the radial plane perpendicular to the desired axis of rotation. Therefore, the rotor 3 is passively magnetically levitated or passively magnetically stabilized in the axial direction A and against inclination (a total of 3 degrees of freedom) by interaction of the coil core 25 of the magnetically active core 31, and actively magnetically levitated in the radial plane (2 degrees of freedom).

[0162] As is generally customary, and in the context of this application, active magnetic levitation refers to levitation that can be actively controlled or regulated by an electromagnetic field generated, for example, by the concentrated winding 61. Passive magnetic levitation or passive magnetic stabilization refers to levitation that cannot be actuated or regulated. Passive magnetic levitation or stabilization is based on a magnetoresistive force that returns the rotor 3 to its desired position if it is deflected from its desired position, i.e., if it is displaced or deflected in the axial direction A, or if it is tilted.

[0163] In the magnetic levitation device 1, unlike conventional magnetic bearings, magnetic levitation and the generation of torque acting on the rotor (optionally) are achieved by an electromagnetic rotating magnetic field. In order to generate a combination of magnetic levitation force and torque for rotating the rotor 3 around the axial direction A, it is possible to precisely position one concentrated winding 61 on each connecting leg 26, as shown in Figure 2.

[0164] On the other hand, an embodiment is also possible in which two different winding systems are provided to generate a combination of magnetic bearing force and torque for rotating the rotor 3. For this purpose, for example, in each example, two precisely adjacent concentrated windings are arranged on each connecting leg 26. That is, one of the concentrated windings is positioned closer to the first end 261 of the connecting leg 26, and the other is positioned closer to the second end 262. One of these two windings belongs to the first winding system of the two winding systems, and the other belongs to the second winding system of the two winding systems.

[0165] In the embodiment shown in Figure 2, each connecting leg 26 is provided with exactly one concentrated winding 61. For example, the values ​​for the current required for levitation and the current required for torque generation, determined by the control unit in each case, are calculated, i.e., added or superimposed, for example using software. The resulting total current is then applied to each concentrated winding 61.

[0166] When 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 electromagnetic rotary drives. Similarly, the magnetic levitation device 1 according to the present invention can also be suitable for other devices such as centrifugal pumps, mixing devices for mixing fluids, stirring devices for mixing fluids in a tank, centrifuges, viscosity sensors, rotary filters, fans, or devices for transferring and rotating wafers in semiconductor manufacturing, for example.

[0167] Figure 7 shows a perspective view of a second embodiment of segment 281 in which the coil core 25 is located. In the following description of the second embodiment of segment 281, only the differences from the first embodiment from Figures 2 to 6 will be described in detail. The description relating to the first embodiment applies similarly or analogously to the second embodiment. The same reference numerals indicate the same or functionally equivalent features described relating to the first embodiment. The main difference in this embodiment is that the connecting leg 26 has a portion 263b that extends radially R rather than obliquely in front of the second end 262. Thus, the connecting leg 26 has a first portion 263a that extends obliquely, i.e., its central axis TA1 makes an angle α greater than 0° and less than 90° with respect to the axial direction A. The angle is preferably between 20° and 80°, and particularly preferably, the angle α is between 45° and 75°. Furthermore, the connecting leg 26 has a second portion 263b, and its central axis TA2 is perpendicular to the axial direction A.

[0168] This second embodiment is advantageous, for example, when it is desired to make the diameter of the rotor 3 or similarly the diameter of the cup-shaped recess 211 smaller than in the first embodiment, but without changing the external mass of the magnetic levitation device.

[0169] Figure 8 shows a perspective view of a third embodiment of segment 281 in which the coil core 25 is located. In the following description of the third embodiment of segment 281, only the differences from the first and second embodiments from Figures 2-6 and 7 will be described in detail. The descriptions relating to the first and second embodiments apply similarly or analogously to the third embodiment. The same reference numerals indicate the same or functionally equivalent features described with respect to the first and second embodiments.

[0170] In the third embodiment, the main difference is that the first portion 263a extends radially R, and the second portion 263b extends obliquely. That is, the central axis TA1 of the first portion 263a is perpendicular to the axial direction A, and the second portion 263b has a central axis TA2 that makes an angle α with the axial direction A, where the angle α is greater than 0° and less than 90°. The angle is preferably between 20° and 80°, and particularly preferably between 30° and 60°.

[0171] The third embodiment is advantageous, for example, when seeking to realize a magnetic levitation device 1 that is compact in the axial direction A. As a result of this arrangement, the entire magnetic levitation device 1 can have a flatter configuration in the axial direction A. Rather, in the third embodiment, at least one concentrated winding 61 (not shown in Figure 8) does not need to be of a conical design, and in this third embodiment, the concentrated winding 61 can have a rectangular shape because it encloses only the first portion 263a of the connecting leg 26. Therefore, in this embodiment, the stator 2 or stator housing 21 can have a flat surface 212 without the need to adapt the shape of the concentrated winding 61, and thus all the advantages of a flat surface 212 of the stator housing 21 described in the previous description are achieved.

[0172] Figure 9 is a plan view of a second exemplary embodiment of the magnetic levitation device 1 according to the present invention, and Figure 10 is a schematic cross-sectional view of the second exemplary embodiment from Figure 9. In the following description of the second exemplary embodiment of the magnetic levitation device 1, only the differences from the first exemplary embodiment from Figure 2 will be described in detail. The description relating to the first exemplary embodiment applies similarly or analogously to the second exemplary embodiment. The same reference numerals refer to the same or functionally equivalent features described relating to the first exemplary embodiment.

[0173] The main difference from the first exemplary embodiment is that the first end 261 of the connecting leg 26 is positioned on the axial upper surface 282 of the back iron 28. Furthermore, the back iron 28 is not divided into segments 281 here. The back iron 28 also has a hexagonal shape.

[0174] In this exemplary embodiment, the back iron 28 is preferably designed as a tape-wound toroidal core. Tape-wound toroidal cores are typically used in transformers and inductors. Since this tape-wound toroidal core is a metal tape that is wound like adhesive tape, the fabrication of the tape-wound toroidal core is very simple. This means that the tape-wound toroidal core has several tape windings. Thus, it becomes possible to fabricate a more cost-effective magnetic levitation device 1.

[0175] Furthermore, using a tape-wound toroidal core as the back iron 28 in this exemplary embodiment is advantageous because it can thereby avoid eddy current losses.

[0176] Since the tape windings are positioned perpendicular to the radial direction R, the magnetic field is transmitted from the connecting leg 26 through the axial direction A to the back iron 28, and is therefore parallel to the tape windings. This means that the magnetic field does not penetrate the tape windings in the radial direction R, and as a result, eddy current losses are avoided.

[0177] In a second exemplary embodiment, six coil cores 25 are arranged on the back iron 28. Ideally, the number of coil cores 25 is equal to the number of n-sided polygons representing the outline of the back iron 28. However, embodiments in which the back iron 28 has a ring-shaped configuration are also possible.

[0178] On the back iron 28, connecting legs 26 are positioned at a first end 261 that is flush with the radially inner surface 283 and the radially outer surface 284. In this case, the connecting legs 26 extend diagonally radially inward to a second end 262 where the pole pieces 27 are positioned. Thus, in this exemplary embodiment, a compact magnetic levitation device 1 is also realized. As a result of positioning the coil core 25 on the axial upper surface 282 of the back iron 28, the back iron 28 does not have any further range in the radial R beyond the range of the coil core 25, so the magnetic levitation device 1 is also more compact in terms of its range in the radial R.

[0179] The concentrated winding 61 is also conical in this case, as well, to ensure the already described advantages of the flat surface 212 (Figure 4) of the stator housing 21.

[0180] Figure 11 is a perspective view of a further embodiment of the pole piece 27.

[0181] One difference in this embodiment is that the end face 272 has a shape transition portion 2723, which is designed as a step, at the edge portion 2722 (Figure 7) that constitutes the transition portion to the pole piece surface 273. In other words, the edge portion 2722 located at the axial upper end of the end face 272 of the pole piece 27, and similarly constituting the radially inner edge of the pole piece surface 273, has a shape transition portion 2723.

[0182] Since the pole piece 27 is designed in a stacking manner from pole elements 275 stacked in the axial direction A, the shape transition section 2723 is designed such that at least one of the pole elements 275 located at the axial upper end of the pole piece 27 has a smaller range in the radial direction R than the other pole elements 275. In other words, this at least one pole element 275 is set back relative to the other pole elements 275 when viewed radially R from the rotor 3, i.e., it is at a greater distance from the rotor 3 than the other pole elements 275.

[0183] However, the shape transition portion 2723 can similarly be understood to mean that the transition portion from the end face 272 to the pole surface 273 has a radius at the edge portion 2721. Therefore, the edge portion 2721 can also be in a missing state.

[0184] A further difference in this embodiment is that the end face 272 has several slots 2724 extending in the axial direction A.

[0185] A first number of slots 2724, more precisely four, extend axially A from the pole piece bottom surface 274, and a second number of slots 2724, similarly four, extend axially A from the pole piece surface 273 opposite the first number of slots 2724. The two numbers of slots 2724 do not touch each other at the center of the end face 272, and as a result, some pole elements 275 are not captured by the slots 2724. However, embodiments in which the slots 2724 extend over all pole elements 275 are also possible. The number of slots 2724 in this embodiment should be understood as merely illustrative and can be more or less.

[0186] In this embodiment, the slots 2724 are arranged parallel or nearly parallel to each other at the end face 272. Arranging multiple slots 2724 parallel to each other is advantageous because it ensures that the slots are also parallel or at least nearly parallel to the path of the magnetic field, and as a result, the slots do not block the magnetic field.

[0187] Introducing slots 2724 to the end face 272 of the pole piece 27 provides electrical insulation. That is, the slots 2724 ensure that the path of eddy currents within the pole element 275 is interrupted, and therefore sealed. Eddy currents generated by the magnetic field generated axially A from the pole element 275 can thus be prevented. As a result, only a small amount of eddy currents remain within the pole piece 27, and the overall eddy current loss of the pole piece 27 is significantly reduced.

[0188] Slot 2724 can be manufactured in various ways. These include, among other things, mechanical methods such as milling, punching, or cutting, and cutting may also include the use of laser cutting and / or water jet cutting and / or wire electrical discharge machining (EDM).

[0189] Figure 12 shows a cross-sectional view of the magnetic levitation device according to the present invention with a pump unit inserted inside.

[0190] A pump unit 300 is inserted into the magnetic levitation device 1 from the first exemplary embodiment (Figure 2) in Figure 12, and the pump unit 300 comprises a rotor 3. Needless to say, the pump unit 300 can also be inserted into the magnetic levitation device 1 from the second exemplary embodiment (Figure 9). The pump unit 300 comprises a pump housing 310 having an inlet 311 and an outlet 312 for the fluid to be conveyed. The rotor 3 is located inside the pump housing 310 and has a plurality of blades 32 for conveying the fluid. The pump housing 310 partitions the pump chamber 313. Furthermore, the pump housing 310 has a cover portion 314 and a base portion 315, the base portion 315 having a cylindrical cup 316 for receiving the rotor 3. Thus, the cup 316 is inserted into a cup-shaped recess 211 of the stator 2.

[0191] Based on this diagram, it becomes clear why the offset between the back iron 28 or back iron surface 285 and the pole piece 27 or pole piece surface 273 is advantageous.

[0192] The pump unit 300 can be inserted into the cup-shaped recess 211 in a tightly fitting manner, resulting in a flat surface 22 of the stator housing 21. Furthermore, as a result of the offset between the pole piece 27 and the back iron 28, the rotor 3 can be levitated to its maximum extent axially above A relative to the axial upper surface 22 of the stator housing 21, i.e., further axially A away from the second end AE2 of the stator 2. As a result of this maximum levitation of the rotor 3 in axial A, the rotor 3 can be configured more compactly, and consequently, the stability of the rotor 3's levitation within the stator 2 is improved.

[0193] More precisely, when the pump unit 300 or rotor 3 is used as a fluid mixer, the blades 32 can have a smaller range in the axial direction A, thereby preventing forces acting strictly upward in the axial direction A on the blades 32. As a result, the tilt moment is reduced, and the levitation of the rotor 3 is well and reliably ensured.

[0194] Figure 13 shows a perspective cross-sectional view of the magnetic levitation device according to the present invention with the mixing unit 400 inserted inside.

[0195] In Figure 13, a mixing unit 400 is inserted into a magnetic levitation device 1 according to the present invention, and the mixing unit 400 comprises a rotor 3. The mixing unit 400 typically comprises a mixing vessel 410 (partially shown here) having an inlet and outlet (not shown here, but the inlet and outlet are often combined) for the substance to be mixed, such as a fluid. The rotor 3 is positioned inside the mixing vessel 410 and has a plurality of blades 32 for mixing the substance. At the axial lower end of the mixing vessel 410, the mixing vessel 410 has a cylindrical cup 411 for receiving the rotor 3. Thereafter, the cup 411 is inserted into a cup-shaped recess 211 of the stator 2.

[0196] Based on the representation in this diagram, it becomes clear why the offset between the back iron 28 or back iron surface 285 and the pole piece 27 or pole piece surface 273 is advantageous.

[0197] The mixing unit 400 can be inserted into the cup-shaped recess 211 in a tight-fitting manner so as to achieve a flat surface 22 of the stator housing 21. Furthermore, as a result of the offset V between the pole piece 27 and the back iron 28, the rotor 3 can be levitated to its maximum extent above axial A relative to the axial upper surface 22 of the stator housing 21, i.e., further away axially A from the second end AE2 of the stator 2. As a result of the rotor 3 being levitated to its maximum extent axially A, the rotor 3 can be designed to be more compact, and consequently, the stability of the rotor 3's levitation within the stator 2 is improved.

[0198] More precisely, when the mixing unit 400 or rotor 3 is used as a fluid mixer, the blades 32 can have a smaller range in the axial direction A, thereby preventing forces acting on the blades 32 further upward in the axial direction A. As a result, the tilt moment is reduced, and the levitation of the rotor 3 is ensured to be good and reliable.

[0199] Figure 14 shows a schematic diagram of the wiring for controlling and adjusting the magnetic levitation device 1 according to the present invention. a) shows a 6-phase winding arrangement, and b) shows a 12-phase winding arrangement.

[0200] The winding arrangement in a) comprises a first three-phase winding set 500 and a second three-phase winding set 501, where the two winding sets 500 and 501 are electrically isolated from each other and are designed to together form a six-phase wiring system. In this example, each winding set comprises six windings 61.

[0201] Each winding set 500, 501 is preferably designed as a star connection and has respective star points 502 to which the associated windings 61 are connected to each other.

[0202] Furthermore, each winding set 500, 501 comprises, in each case, two windings 61 connected in series, which form a single phase, resulting in one series winding for each phase. The windings 61 are connected in a preferred orientation to ensure a specified magnetic polarity and a symmetrical magnetic field distribution within the system.

[0203] In a preferred embodiment, the two windings connected in series are wired with opposing polarities, i.e., the two windings have opposing winding directions.

[0204] The winding arrangement in b) includes four independent 3-phase winding sets 600, 601, 602, and 603, which together form a 12-phase system.

[0205] Each of the four winding sets 600, 601, 602, and 603 is preferably designed as a star connection, and in each case has its own star point 604, at which three related windings 61 are electrically connected to one another. The star points 604 of the individual winding sets 600, 601, 602, and 603 are particularly preferably electrically isolated from one another, resulting in a total of four independent star points 604.

[0206] Each winding set 600, 601, 602, and 603 has three windings 61, and in each example, one winding 61 is provided for each phase.

[0207] Needless to say, all exemplary embodiments shown in the description of the drawings can be combined with one another in any form, each with its own features and components.

Claims

1. A magnetic levitation device for non-contact magnetic levitation of a rotor (3) having a disc-shaped or ring-shaped magnetic active core (31), wherein the magnetic levitation device comprises a stator (2) extending in the axial direction (A) and having a cup-shaped recess (211), the cup-shaped recess (211) being located at the axial end of the stator (2) into which the rotor (3) can be inserted, the stator (2) having a plurality of coil cores (25), each of the plurality of coil cores (25) having connecting legs (26) and pole pieces (27), each connecting leg (26) extending from a first end (261) to a second end (262) In a magnetic levitation device, the first end (261) of the pole piece (27) extends in a manner in which the pole piece (27) abuts against the back iron (28), and each pole piece (27) has a second contact surface (271) that abuts against the second end (262) of the connecting leg (26), and each pole piece (27) extends radially (R) from the second contact surface (271) to an end face (272), the radial direction (R) being perpendicular to the axial direction (A), all end faces (272) being arranged around the cup-shaped recess (211), and at least one concentrated winding (61) being arranged on each connecting leg (26), the winding surrounding each of the connecting legs (26), A magnetic levitation device characterized in that each connecting leg (26) extends obliquely with respect to the axial direction (A), and as a result, the distance of the second end (262) of each connecting leg (26) from the cup-shaped recess (211) in the radial direction (R) is smaller than that of the first end (261).

2. The magnetic levitation device according to claim 1, wherein the back iron (28) connects the first ends (261) of all the connecting legs (26).

3. The magnetic levitation device according to claim 1 or 2, wherein the back iron (28) has several segments (281), and the segments (281) are preferably manufactured in a stacking manner from back iron elements (286) stacked in the axial direction (A).

4. The magnetic levitation device according to claims 1 to 3, wherein the back iron (28) has an axial upper surface (282), and the first end (261) of the connecting leg (26) is positioned on the axial upper surface (282).

5. The magnetic levitation device according to claims 1 to 3, wherein the back iron (28) has a radially inner surface (283), and the first end (261) of the connecting leg (26) is positioned on the radially inner surface (283).

6. The magnetic levitation device according to any one of claims 1 to 5, wherein the at least one concentrated winding (61) is of a conical design.

7. The magnetic levitation device according to claim 6, wherein the at least one concentrated winding (61) has a lower end (611) and an upper end (612), the lower end (611) facing the first end (261) of the connecting leg (26), the upper end (612) facing the second end (262) of the connecting leg (26), and the at least one concentrated winding (61) has a first outer diameter (WA1) at the lower end (611) and a second outer diameter (WA2) at the upper end (612), the first outer diameter (WA1) being greater than the second outer diameter (WA2).

8. The magnetic levitation device according to any one of claims 1 to 7, wherein the pole piece (27) is made from a soft magnetic material.

9. The magnetic levitation device according to any one of claims 1 to 8, wherein the pole pieces (27) are manufactured in a stacking manner from pole elements (275), the pole elements (275) are stacked in the axial direction (A), and / or each connecting leg (26) is manufactured in a stacking manner from elements (264), the elements (264) are stacked in the circumferential direction of the stator (2).

10. The magnetic levitation device according to any one of claims 1 to 9, wherein the end face (272) of the pole piece (27) is designed as a curved surface, and the end face (272) is preferably rounded, and the rounding is designed coaxially with respect to the cup-shaped recess (211).

11. The magnetic levitation device according to any one of claims 1 to 10, wherein the end face (272) is designed to be wider in the circumferential direction than the maximum circumferential range of the second contact surface (271).

12. The magnetic levitation device according to any one of claims 1 to 11, wherein the end face (272) has a rounded edge (2722) that represents a transition portion to the pole surface (273).

13. The magnetic levitation device according to any one of claims 1 to 12, wherein the stator (2) is designed to generate torque, and by the torque, the rotor (3) can be magnetically driven in a non-contact manner for rotation about the axial direction (A).

14. The magnetic levitation device according to claim 13, which is designed as an electromagnetic rotary drive, a mixing device, a centrifuge, a cross-flow fan, a rotary filter, or a viscometer.

15. A pump unit for a magnetic levitation device (1) according to any one of claims 1 to 14, wherein the pump unit (300) comprises the rotor (3), the pump unit (300) has a pump housing (310) having an inlet (311) and an outlet (312) for a fluid to be transported, the rotor (3) is located within the pump housing (310), and the rotor (3) has a plurality of blades (32) for transporting the fluid. A pump unit having a pump housing (310) that partitions a pump chamber (313), the pump housing (310) having a cover portion (314) and a base portion (315), the base portion (315) having a cylindrical cup (316) for receiving the rotor (3), the cup (316) being insertable into the cup-shaped recess (211) of the stator (2) of the magnetic levitation device (1) according to any one of claims 1 to 14.

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