Magnetic levitation devices and centrifugal pumps

Abstract

A proposal for a magnetic levitation device that can reliably and with very high precision determine the position of a rotor using a magnetic field sensor, and a centrifugal pump equipped with such a magnetic levitation device. [Solution] The rotor 3 has a stator 2 including a plurality of coil cores 25, and a plurality of magnetic field sensors for determining the position of the rotor 3 are arranged around a cup-shaped recess 211. A ring-shaped retaining device 9 is provided for the magnetic field sensors, and the ring-shaped retaining device has a cavity for each magnetic field sensor, the cavity is bounded radially by an inner wall and an outer wall, the magnetic field sensor can be pressed into the cavity, and the cavity is sized such that the inner wall and outer wall are flush with respect to the magnetic field sensor.

Description

Technical Field

[0005] , ,

[0006]

[0001] The present invention relates to a magnetic levitation device described in the preamble of the independent patent claim and a centrifugal pump provided with such a magnetic levitation device.

Background Art

[0002] A magnetic bearing device that magnetically supports a rotor in a non-contact manner has the advantage of not requiring a mechanical bearing for the rotor. The rotor is supported or stabilized by the magnetic force generated by the stator of the magnetic bearing device. Such a magnetic bearing device is particularly suitable for pump transfer, mixing, centrifugation, or stirring devices, such as blood pumps, where substances that are very susceptible to influence are transported, for pump transfer, mixing, centrifugation, or stirring devices that are very demanding in terms of purity, such as in the pharmaceutical or biotechnological industries, or for pump transfer, mixing, centrifugation, or stirring devices that transport abrasive or erosive substances that would very quickly destroy mechanical bearings, such as slurries, sulfuric acid, phosphoric acid, or other chemical substances in semiconductor industry pumps or mixers.

[0003] Such a magnetic bearing device is used in the biotechnological industry, for example, together with a bioreactor, in a centrifugal pump that transports fluid into or out of the bioreactor, or in a mixing device that mixes fluid within the bioreactor. Such a magnetic bearing device is used not only in the semiconductor industry for transporting highly erosive or abrasive substances, but also in a rotating device that rotates a wafer, for example.

[0004] It is also known to use a magnetic bearing device in a viscometer.

[0005] An advantageous, known per se design of the magnetic bearing device is the template structure design, and the present invention also relates to the template structure.

[0006] A characteristic feature of the temple structure is that the stator of the magnetic bearing device comprises multiple coil cores, each of which has a longitudinal leg extending axially from a first end to a second end. Here, the axial direction refers to the direction defined by the desired axis of rotation of the rotor supported by the magnetic bearing device. The desired axis of rotation is the axis around which the rotor rotates when the rotor is in operation, centered with respect to the stator and not tilted. Each coil core, in addition to its longitudinal leg, has a transverse leg located at the second end of the longitudinal leg, which extends radially, usually inward, and where the radial direction is perpendicular to the axial direction. The transverse leg thus extends substantially perpendicular to the longitudinal leg. Each coil core has an L-shape, and the transverse leg forms a shorter leg of the L. The rotor to be supported is then positioned between the transverse legs.

[0007] The name of this structure comes from the fact that its multiple longitudinal legs, extending axially, resemble the pillars of a temple.

[0008] The stator of a magnetic bearing device, in one design, comprises six coil cores arranged in a circular and evenly spaced configuration around a cup-shaped recess into which a rotor can be inserted. The first ends of the longitudinal legs are typically circumferentially connected by back irons that act to conduct magnetic flux. The rotor to be supported comprises a magnetically effective core, such as a permanent magnetic disk or permanent magnetic ring, positioned between the radially inward ends of the lateral legs, and rotating axially in operation, where the rotor is magnetically supported without contact with the stator.

[0009] It is not necessarily true that the magnetically effective core of the rotor in such magnetic bearing devices must be designed using permanent magnet techniques. Designs are known in which the magnetically effective core of the rotor is designed using techniques that do not involve permanent magnets, i.e., without permanent magnets. In this case, the magnetically effective core of the rotor is designed using ferromagnetic techniques, for example, and is made of iron, nickel-iron, cobalt-iron, silicon-iron, mu-metal, or another ferromagnetic material.

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

[0011] The longitudinal legs support the windings and generate the electromagnetic field necessary to magnetically support the rotor in a non-contact manner. The windings are designed such that, for example, one concentrated winding is wound around each longitudinal leg, i.e., the coil axis of each concentrated winding is axially extended. Here, the coil axis of the concentrated winding is axially extended, and the concentrated winding is not positioned in the radial plane in which the rotor or the magnetically effective core of the rotor is supported in operation, which is a typical temple structure.

[0012] It is possible to design the system to have exactly one concentrated winding at each longitudinal leg. In other designs, multiple concentrated windings, for example, exactly two, are provided at each longitudinal leg. It is also possible to design the system so that the winding is wound around two circumferentially adjacent longitudinal legs, and so that both of these two adjacent longitudinal legs are located inside the concentrated winding.

[0013] It is crucial that a reliable and safe non-contact magnetic bearing for the rotor can accurately determine the rotor's current position in the radial plane in each case and adjust its position in the radial plane to a desired location. To determine the rotor's position, it is known, for example from International Publication 2014 / 036419, to place multiple magnetic field sensors, such as Hall sensors, on the magnetic bearing device so as to be positioned around the rotor's magnetically effective core. The rotor's current position is then determined as accurately as possible from the signals of the magnetic field sensors. However, since the magnetic field sensors also detect all magnetic fields at each position, i.e., the stator magnetic field, it is often very difficult to determine the rotor's precise position in the radial plane from the signals of the magnetic field sensors. [Prior art documents] [Patent Documents]

[0014] [Patent Document 1] International Publication No. 2014 / 036419 [Overview of the Initiative] [Problems that the invention aims to solve]

[0015] Therefore, an object of the present invention is to propose a magnetic levitation device for non-contact magnetic levitation of a rotor having a ring-shaped or disk-shaped magnetically effective core, which can reliably and with very high precision determine the rotor's position by a magnetic field sensor. Furthermore, an object of the present invention is to propose a centrifugal pump equipped with such a magnetic levitation device. [Means for solving the problem]

[0016] The subject matter of the present invention, which satisfies this objective, is characterized by the features of the independent patent claims.

[0017] Accordingly, according to the present invention, a magnetic levitation device is proposed for non-contact magnetic levitation of a rotor including a disk-shaped or ring-shaped magnetically effective core, the magnetic levitation device having a stator comprising a plurality of coil cores, each of which includes a longitudinal leg extending axially from a first end to a second end and a transverse leg located at the second end of the longitudinal leg and extending radially perpendicular to the axial direction, each longitudinal leg having at least one concentrated winding, the winding surrounding each longitudinal leg, the stator having a cup-shaped recess into which a rotor can be inserted, the cup-shaped recess located at the axial end of the stator, the transverse leg being located around the cup-shaped recess, and a plurality of magnetic field sensors for determining the position of the rotor being located around the cup-shaped recess. A ring-shaped retaining device is provided for the magnetic field sensors, the ring-shaped retaining device having a cavity for each magnetic field sensor, the cavity being defined radially by an inner wall and an outer wall, the magnetic field sensor being able to be pressed into the cavity, and the cavity being sized such that the inner and outer walls are flush with respect to the magnetic field sensor.

[0018] By providing a ring-shaped holder having cavities for each magnetic field sensor, with inner and outer walls dimensioned to be flush with the magnetic field sensor, the position of each magnetic field sensor can be known with extremely high precision. In particular, the position of the magnetic field sensor relative to the cup-shaped recess is known with high precision, which allows for very accurate determination of the rotor position in the cup-shaped recess. In particular, the position of each magnetic field sensor is defined solely by the position of the cavity and does not depend, for example, on how the magnetic field sensor is soldered to the circuit board or bonded to the structure. Even if the position of the magnetic field sensor is determined by such connection as soldering or bonding, this generally results in inaccuracies in placement, which adversely affects the accuracy of determining the rotor position. In embodiments of the present invention, since the soldered or bonded connection does not affect the position of the magnetic field sensor, this results in very high precision in determining the rotor position.

[0019] In a preferred embodiment, the circuit board is positioned axially between the windings and the lateral legs, all magnetic field sensors are arranged on the circuit board, and the retaining device is designed to house the circuit board. This has the advantage that all magnetic field sensors can be connected to the circuit board first, thereby forming electrical connections on the circuit board for controlling the magnetic field sensors and receiving measurement signals. Subsequently, the circuit board with the magnetic field sensors connected is then inserted into the retaining device, and the magnetic field sensors are pushed into the cavity. Finally, the circuit board is securely connected to the retaining device, for example, by screws and / or by a potting compound poured into the retaining device.

[0020] Here, it is preferable that the holding device has a ring-shaped edge with a shoulder, the shoulder being positioned radially inward with respect to the edge, and the circuit board being positioned relative to the shoulder. This shoulder thus forms a support for the circuit board, allowing the circuit board to be positioned in the holding device in a very simple manner.

[0021] Furthermore, it is preferable that the edges are designed to protrude beyond the circuit board in the axial direction. This means that potting compound can be poured into the retaining device, and the circuit board is completely covered with the embedding resin.

[0022] According to a preferred embodiment, the retaining device has separate notches for each coil core, the notches encircling the coil core and accommodating the lateral legs of the coil core.

[0023] In this case, it is advantageous that each cavity is positioned between two adjacent notches in the circumferential direction. This allows each magnetic field sensor to be positioned between two adjacent coil cores in the circumferential direction.

[0024] According to a particularly preferred embodiment, exactly six coil cores are provided in the magnetic levitation device.

[0025] The magnetic levitation device preferably includes exactly six magnetic field sensors preferably arranged at equal intervals around the cup-shaped recess.

[0026] In a preferred embodiment, the holding device is filled with a first potting compound such that the circuit board is completely covered by the potting compound. The first potting compound is particularly preferably a flexible potting compound. In the context of the present application, a flexible potting compound means a potting compound having a Shore hardness D of less than 40. For example, silicone or polyurethane is suitable as the first potting compound.

[0027] According to a particularly preferred embodiment, the coil core with the winding disposed thereon is arranged within a housing into which a second potting compound is poured, and the second potting compound is a thermally conductive potting compound. This second thermally conductive potting compound is a hard thermal potting compound, such as an epoxy resin. As a result, the first potting compound and the second potting compound are different from each other. During operation of the magnetic levitation device, particularly in the region of the holding device in which the magnetic field sensor is disposed therein, strong and frequent temperature fluctuations can occur. The flexible potting compound is more resistant to such fluctuations. Thus, the flexible potting compound is preferably poured into the holding device and is more flexible than the hard potting compound poured into the housing. In particular, the second potting compound surrounding the coil core and the winding disposed thereon preferably has particularly good thermal conductivity in order to dissipate as efficiently as possible the heat generated, for example, the heat generated by copper losses and iron losses. To achieve a high thermal conductivity, a filler having good thermal conductivity, such as graphite powder, carbon fiber, carbon nanotubes, aluminum oxide powder, boron nitride powder or other ceramic powders, is preferably added to the second thermal potting compound. These fillers improve the thermal conductivity but also result in a higher hardness of the cured potting compound. Thus, the second thermal potting compound has a higher hardness, particularly a higher Shore hardness D, than the first potting compound.

[0028] With regard to positioning magnetic field sensors as accurately as possible, it is advantageous to provide separate guide elements for each cavity that form an inner or outer wall defining the cavity boundary. Such separate guide elements are usually easier to manufacture with much higher precision than the entire holding device, which is typically manufactured by, for example, injection molding. To form a cavity for a magnetic field sensor, a separate guide element is inserted axially into a recess in the holding device provided for this purpose, thereby the separate guide element then forms an inner or outer wall defining the cavity boundary in the radial direction. Preferably, the separate guide element is connected to the holding device in a shape-locking manner, for example, by press-fitting.

[0029] Preferably, the stator has a confinement can that forms the axial end of the starter, the confinement can has a cup-shaped recess into which the rotor can be inserted, and the confinement can surrounds the retaining device radially outward. In this preferred embodiment, the confinement can is preferably designed as a separate confinement can having a cup-shaped recess. Particularly for structural reasons, it is preferable that the confinement can surround the second retaining device radially outward. In this base, the axial end region of the second retaining device is located within the confinement can and is completely surrounded by the confinement can when viewed circumferentially.

[0030] Preferably, the retaining device is formed from plastic. For example, the retaining device is designed as an injection-molded part manufactured by an injection molding method.

[0031] Furthermore, it is preferable that the containment can be formed from plastic. The containment can can also be designed as an injection-molded part.

[0032] According to a preferred embodiment, the magnetic levitation device has a housing that includes a stator housing and a control housing arranged adjacent to each other in the axial direction, the stator housing being designed to house a coil core in which concentrated windings are arranged, and the control housing being designed to house a control unit for controlling the windings for generating an electromagnetic field and supplying electrical energy to the windings.

[0033] Preferably, the housing is designed so that a coil core with concentrated windings can be inserted into the stator housing in a first axial mounting direction and a control unit can be inserted into the control housing in a second mounting direction, where the first mounting direction is opposite to the second mounting direction. Preferably, the housing has two regions separated from each other, one region forming the stator housing and the other region forming the control housing. For example, these two regions can be separated from each other by a wall having, for example, a passage for electrical connections. Thus, the housing is preferably designed as a single unit with respect to the circumferential direction.

[0034] In a particularly preferred embodiment, the stator of the magnetic levitation device is designed to generate torque that can magnetically drive the rotor without contact for rotation around the axial direction.

[0035] Furthermore, the present invention proposes a centrifugal pump for transporting fluids, comprising a magnetic levitation device and a rotor having a magnetically effective core, wherein the rotor can be inserted into a cup-shaped recess of a containment can, and the rotor is designed as the rotor of a centrifugal pump.

[0036] Further advantageous measures and embodiments of the present invention are evident from the dependent claims.

[0037] The present invention will be described in more detail below with reference to examples and drawings. [Brief explanation of the drawing]

[0038] [Figure 1] This is a cross-sectional view of one embodiment of the magnetic levitation device according to the present invention. [Figure 2] This is a perspective view of the embodiment shown in Figure 1 in an oblique exploded view. [Figure 3] This is a perspective view of the stator and retaining device. [Figure 4] This is an exploded perspective view of the coil core, windings, and retaining device. [Figure 5] This is a perspective view of the retaining device from the direction of the first end of the longitudinal leg of the coil core. [Figure 6] This is the same as Figure 5, but viewed from the opposite direction. [Figure 7] This is an exploded perspective view of a circuit board equipped with a holding device and a magnetic field sensor. [Figure 8] This is a cross-sectional view of a holding device into which a circuit board has been inserted. [Figure 9] This is a detail of Figure 8 in the enlarged view. [Figure 10] Figure 9 is a perspective view of the guide element. [Figure 11] This is a cross-sectional view of the stator's containment chamber. [Figure 12] This is a schematic cross-sectional view of an embodiment of the centrifugal pump according to the present invention in an axial cross-sectional view. [Modes for carrying out the invention]

[0039] Figure 1 shows a cross-sectional view of one embodiment of the magnetic levitation device according to the present invention, the entire device being denoted by reference numeral 1. The magnetic levitation device 1 is designed to magnetically levitate a rotor 3 having a disk-shaped or ring-shaped magnetically effective core 31 in a non-contact manner.

[0040] Figure 2, for better understanding, also shows an exploded perspective view of the embodiment of Figure 1, and the rotor 3 is not shown in Figure 2. The magnetic levitation device 1 is designed according to a temple structure and comprises a stator 2, which comprises a plurality of coil cores 25, in this case six coil cores 25, each of which comprises a longitudinal leg 26 extending axially A from a first end 261 to a second end 262, and a transverse leg 27 positioned perpendicular to the longitudinal leg 26 and extending radially perpendicular to axial A. Each transverse leg 27 is bounded radially by an end face 271 that forms the pole of the associated coil core.

[0041] At least one concentrated winding 61, in this embodiment just one concentrated winding 61, is provided on each longitudinal leg 25, surrounding each longitudinal leg 26.

[0042] The magnetic levitation device 1 includes a housing 10, and a coil core 25 is located inside the housing 10.

[0043] Figures 3 and 4 show further diagrams of the stator 2 of an embodiment of the magnetic levitation device 1 for better understanding, with the housing 10 not shown. Figure 3 shows a perspective view of the stator 2 and retaining device 9, which will be described in more detail. Furthermore, Figure 3 shows a back iron 22, which connects all the first ends 261 of the longitudinal legs 26, i.e., the lower ends 261 according to the illustration (Figure 1), to each other and works to conduct magnetic flux. The back iron 22 is preferably designed in a ring shape. Figure 4 shows an exploded perspective view of the coil core 25 with the concentrated windings 61 located therein, and the retaining device 9.

[0044] The housing 10 is preferably formed from a metallic material, such as aluminum or stainless steel. To further enhance chemical resistance, the housing 10 can be coated, preferably with a plastic coating made from a highly chemically resistant plastic. Examples of such plastics include PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy polymer), ECTFE (ethylene chlorotrifluoroethylene), ETFE (ethylene tetrafluoroethylene), epoxy resin (polyepoxy), PPA (polyphthalamide), and PE (polyethylene). Depending on the intended application, the housing 10 may also be formed from titanium or chromium steel.

[0045] The stator 2 further includes a containment can 21 (see also Figure 11) having a cup-shaped recess 211 into which a rotor 3 to be levitated can be inserted (see Figure 1). The containment can 21 forms one of the two axial ends of the stator 2 or the magnetic levitation device 1, the upper axial end of the stator 2 as shown in Figure 1. A housing cover 11 that closes the housing 10 is located at the other axial end of the magnetic levitation device 1.

[0046] The containment can 21 is securely connected to the housing 10, for example, by a form-locking connection and / or by an elastic seal 201. Preferably, the containment can 21 is connected to the housing 10 in an hermetically sealed manner. The housing cover 11 is securely connected to the housing 10, for example, by screws 111 (Figure 1), and a sealing element 105 is optionally positioned between the housing cover 11 and the housing 10. The sealing element 105 can be designed in particular as a flat seal. Preferably, the housing cover 11 is connected to the housing 10 in an hermetically sealed manner.

[0047] Particularly preferably, the housing 10, together with the containment can 21 and the housing cover 11, forms an hermetically sealed housing in which the other components of the stator 2 are sealed in an hermetically sealed state. Preferably, the housing 10 is filled with a potting compound with high thermal conductivity, such as epoxy resin, so that the components placed inside the housing 10 are surrounded by the potting compound. In this way, the overall thermal resistance is reduced and vibrations are dampened.

[0048] Preferably, the housing cover is made of plastic. Chemical-resistant plastics such as polypropylene are preferred, especially for applications in chemically corrosive environments.

[0049] The lateral legs 27 of the coil core 25 are positioned inside the containment can 21 such that the end faces 271 of the lateral legs 27 are positioned around the cup-shaped recess 211.

[0050] The coil cores 25 of the stator 2 are arranged at equal intervals on a circular line, so that when the rotor 3 is inserted into the cup-shaped recess 211, the end faces 271 surround the magnetically effective core 31 of the rotor 3. Just one concentrated winding 61 is provided at each longitudinal leg 26, surrounding the longitudinal legs 26.

[0051] In other embodiments, two or more concentrated windings can be arranged on the longitudinal leg 26. For example, there is an embodiment in which exactly two concentrated windings are provided on each longitudinal leg 26, each surrounding its respective longitudinal leg 26, and the two windings located on the same longitudinal leg 26 are arranged adjacent to each other with respect to the axial direction A.

[0052] The concentrated winding 61 works to generate an electromagnetic field that allows the rotor 3 to be magnetically levitated without contact within the cup-shaped recess 211 of the containment can 21.

[0053] Furthermore, a control unit 40 is provided to control the winding 61 and supply electrical energy to the winding 61. The control unit 40 includes, in particular, power electronics, such as a rectifier inverter, which supplies the required current to the winding 61. The control unit 40 is shown in Figures 1 and 2. Particularly preferably, the control unit 40 is also located inside the housing 10, for example, below the first end 261 of the longitudinal leg 26 of the coil core 25 as shown (Figure 1). The control unit 40 is also preferably enclosed in a thermal potting compound or coupled to the coil core 25 of the housing 10 and the back iron 22 and / or stator 2. Preferably, the control unit 40 includes an electronic circuit board 41 on which various electronic components 42 are arranged.

[0054] As can be seen particularly in Figures 1 and 2, the housing 10 preferably includes two separate regions adjacent to each other with respect to the axial direction A, one region forming the stator housing 101 and the other region forming the control housing 102. The stator housing 101 of the housing 10 is designed to house the coil core 25 on which the windings 61 are arranged, and the control housing 102 is designed to house the control unit 40.

[0055] In a preferred manner, the housing 10 includes an internal cup 13 that is substantially cylindrical in shape, and the internal cup 13 is positioned radially inward relative to the windings 61 in an internal space surrounded by the windings 61. The internal cup 13 is connected to the outer wall 15 of the housing 10 via a flange-like projection 14. The outer wall 15 forms the radially outer boundary of the housing 10. Particularly preferably, the internal cup 13 and the flange-like projection 14 are integral parts of the housing 10. The outer wall 15, the flange-like projection 14 and the internal cup 13 are designed as a whole to form a single unit, preferably an integrated housing 10.

[0056] The internal cup 13 and flange-shaped projection 14 separate the area of ​​the housing 10 where the stator housing 101 is formed from the area where the control housing 102 is formed.

[0057] The internal cup 13, connected to the flange-like projection 14, extends axially A from the radially inner edge of the flange-like projection 14, as particularly evident in Figure 1, and is positioned radially inward relative to the winding 61 and the back iron 22 within the internal space surrounded by the winding 61. With respect to the radial direction, the internal cup 13 is positioned adjacent to the longitudinal legs 26 of the coil core 25 or the winding 61 located on the longitudinal legs, thereby enabling the internal cup 13 to absorb and dissipate heat generated by the winding 61 and the coil core 25 particularly well. With respect to the axial direction A, the internal cup 13 extends substantially to the cup-shaped recess 211 of the containment can 21.

[0058] As can be seen particularly in Figure 2, the stator housing 101 of the housing 10 is designed to have an internal space having a substantially circular or ring-shaped cross-sectional area perpendicular to the axial direction A. This is preferable because it allows the stator housing 101 to accommodate the ring-shaped back iron 22, along with the coil core 25 arranged around the back iron 22. The control housing 102 of the housing 10 is designed to have an internal space having a substantially rectangular or square cross-sectional area perpendicular to the axial direction A. This is preferable because it allows the control housing 102 to be particularly well suited to accommodating the electronic circuit board 41 of the control device 40, which is preferably designed to be rectangular or square. In particular with respect to manufacturing, the design of the circuit board 41 is rectangular or square, much simpler than, for example, a round design.

[0059] In this embodiment of the stator housing 101 and control housing 102, the axial end of the stator 2 through which the containment can 21 closes the housing 10 has a substantially circular cross-section, thereby giving the containment can 21 a round or circular ring-shaped design. In contrast, the axial end of the stator 2 through which the housing cover 11 closes the housing 10 has a substantially rectangular or square cross-section, thereby giving the housing cover 11 a rectangular or square design.

[0060] Figure 1 shows some components of the control unit 40, along with illustrative features. The control unit 40 includes, for example, an electronic circuit board 41 on which power electronics for controlling electronic components 42, such as windings 61. For example, the electronic circuit board 41 may further include evaluation electronics for evaluating signals from sensors, such as magnetic field sensors, or it may function as a communication interface. The circuit board 41 is preferably designed as an electronic print or PCB (printed circuit board). Furthermore, a connecting cable 45 is provided, which is connected to the electronic circuit board 41 via a cable connector (not shown) or plug. The connecting cable 45 is routed out of the housing 10 and serves, for example, to supply power to the magnetic levitation device 1. The connecting cable 45 is routed out of the housing 20 by a sealed cable bushing 47. Preferably, the cable bushing 47 is designed to be hermetically sealed.

[0061] The electronic circuit board 41 of the control unit 40 is connected to the windings 61 via connecting wires (not shown), such as cables, to control the windings and supply energy to them. It should be understood that a feedthrough or opening is provided between the control housing 102 and the stator housing 101 for the connecting wires to pass through. Such a feedthrough may be located, for example, in a flange-like projection 14 or an internal cup 13.

[0062] Preferably, the electronic substrate 41 is placed directly on the flange-shaped projection 14, thereby positioning the electronic substrate relative to the flange-shaped projection 14. In this way, heat generated in the control unit 40 can be dissipated particularly efficiently through the housing 10. Preferably, the main heat source in the control unit 40, for example, the circuit breaker for the winding 61, is located in the region of the electronic substrate 41 that is positioned relative to the flange-shaped projection 14.

[0063] The internal space of the internal cup 13, that is, the space surrounded by the internal cup 13, can be used for further electronic components, electronic circuit boards, or plugs or connectors. These are not shown in Figure 1 for a clearer overview.

[0064] In a particularly preferred embodiment, the stator 2 is designed not only to magnetically levitate the rotor 3 in a non-contact manner, but also to apply torque to the rotor 3 or its magnetically effective core 31, which drives the rotor 3 to rotate around a desired axis of rotation. Here, the desired axis of rotation is the axis around which the rotor 3 rotates when the rotor 3 is in operation, centered relative to the stator 2 and not tilted, as shown in Figure 1. This desired axis of rotation extends in the axial direction A, i.e., in this preferred embodiment, the rotor 3, located within the containment can 21 of the stator 2, can be driven to rotate around the axial direction A. Typically, the desired axis of rotation coincides with the central axis of the stator 2, which extends in the axial direction A.

[0065] In this embodiment, the concentrated winding 61 thus generates an electromagnetic rotation field that can magnetically levitate the rotor 3 without contact with the stator 2 and drive it to rotate without contact around the axial direction A.

[0066] The number of coil cores 25, while preferred, should be understood as merely one example. Of course, embodiments are also possible in which the stator 2 has fewer than six coil cores 25, for example, five, four, or three, or in which the stator 2 has more than six coil cores 25, for example, seven, eight, or nine, or even more coil cores 25.

[0067] The rotor 3 comprises a magnetically effective core 31, designed in the shape of a ring or a disk. As shown in Figure 1, the magnetically effective core 31 is designed as a ring, defining a magnetic center plane. Alternatively, the magnetically effective core 31 can also be designed as a disk. Typically, in the case of a disk-shaped or ring-shaped magnetically effective core 31, the magnetic center plane is the geometric center plane of the magnetically effective core 31 of the rotor 3, perpendicular to the axial direction A. In operation, the magnetically effective core 31 is levitated in a radial plane E that stands perpendicular to the axial direction A. The radial plane is shown in Figure 1 by a line E that stands perpendicular to the axial direction A. Therefore, the radial plane E is a plane that stands perpendicular to the axial direction A and contains line E.

[0068] The radial plane E is the plane in which, in the operating state, the magnetically effective core 31 of the rotor 3 is actively magnetically levitated between the end faces 271 of the stator 2. When the rotor 3 is not tilted and is not deflected in the axial direction A, the magnetic center plane lies in the radial plane E. The radial plane E defines the zy-plane of the Cartesian coordinate system, whose z-axis extends in the axial direction A.

[0069] The radial position of the magnetically effective core 31 or rotor 3 refers to the position of the rotor 3 in the radial plane E.

[0070] To understand the present invention, only the magnetically effective core 31 is shown in the rotor 3 in Figure 1. It should be understood that the rotor 3 may, of course, include further components such as a jacket or encapsulating container, preferably formed from plastic, metal, alloy, or ceramic or ceramic material. Furthermore, the rotor 3 may also include vanes (see, for example, Figure 12) or other components for mixing, stirring, or pumping fluids.

[0071] When the rotor 3 is inserted into the cup-shaped recess 211 of the containment can 21, the rotor 3, and in particular the magnetically effective core 31 of the rotor 3, is surrounded by the radially outward-facing end faces 271 of the lateral legs 27 of the coil core 25 of the stator 2. Thus, the lateral legs 27 form a plurality of pronounced stator poles, in this case six stator poles. The lateral legs 27 are located at the upper ends of the longitudinal legs 26 in the radial plane E. Each lateral leg 27 extends radially toward the rotor 3.

[0072] When the magnetically effective core 31 of the rotor 3 is in the desired position during operation, the magnetically effective core 31 is centered between the end faces 271 of the lateral legs 27, and therefore the lateral legs 27, which are positioned in the radial plane E, are also positioned in the magnetic center plane. As shown in the figure, the concentrated winding 61 is positioned below the radial plane E and is aligned such that the coil axis of the concentrated winding extends in the axial direction A.

[0073] All first ends 261 of the longitudinal leg 26, i.e., the lower end 261 as shown in the figure (Figure 1), are connected to one another by a back iron 22. The back iron 22 is preferably designed in a ring shape. Embodiments are possible in which the back iron 22 extends radially inward along all first ends 261 of the longitudinal leg 26 (see, for example, Figure 1).

[0074] To generate the electromagnetic field required for the magnetic levitation of the rotor 3, and the electromagnetic field required to selectively generate torque on the rotor 3, the longitudinal legs 26 of the coil core 25 carry windings designed as concentrated windings 61.

[0075] In operation, these electromagnetic rotating fields are generated by these concentrated windings 61, and these electromagnetic rotating fields can apply an arbitrarily adjustable lateral force in the radial direction to the rotor 3, thereby allowing the radial position of the rotor 3, i.e., the position of the rotor 3 in the radial plane E perpendicular to the axial direction A, to be actively controlled or adjusted. Selectively, these electromagnetic rotating fields generate additional torque on the rotor 3.

[0076] The "magnetically effective core 31" of the rotor 3 refers to the region of the rotor 3 that magnetically interacts with the stator 2 in order to generate magnetic levitation and selectively generate torque.

[0077] As already mentioned, in this embodiment, the magnetically effective core 31 is designed in a ring shape. Furthermore, the magnetically effective core 31 is designed to be a permanent magnet. For this purpose, the magnetically effective core 31 may contain at least one permanent magnet, but may also contain multiple permanent magnets, or, as in the embodiment described herein, may be composed entirely of a permanent magnetic material so that the magnetically effective core 31 is a permanent magnet. The magnetically effective core 31 is, for example, magnetized radially.

[0078] These ferromagnetic or ferrimagnetic materials, which are magnetically rigid, i.e., possess high coercivity, are generally called permanent magnets. Coercivity is the magnetic field strength required to demagnetize a material. Within the framework of this application, a permanent magnet is understood to be a component or material that possesses coercivity, more precisely, coercivity in a magnetic context exceeding 10,000 A / m.

[0079] Embodiments are also possible in which the magnetically effective core 31 is designed without permanent magnets, i.e., without permanent magnets. In this case, the rotor 3 is designed, for example, as a magnetoresistive rotor. In this case, the magnetically effective core 31 of the rotor 3 is formed from, for example, a soft magnetic material. Suitable soft magnetic materials for the magnetically effective core 31 are, for example, ferromagnetic or ferrimagnetic materials, i.e., iron, nickel-iron, cobalt-iron, silicon-iron, and mu-metal.

[0080] Furthermore, embodiments are possible in which the magnetically effective core 31 of the rotor 3 includes both a ferromagnetic material and a permanent magnetic material. For example, a permanent magnet can be disposed of or inserted into a ferromagnetic substrate. Such embodiments are advantageous, for example, when it is desirable to reduce the cost of a large rotor by saving on permanent magnetic material.

[0081] It is also possible to implement a rotor that is designed according to the principle of a cage rotor.

[0082] Both the ring-shaped back iron 22 and the coil core 25 of the stator 2 function as magnetic flux conducting elements that conduct magnetic flux, and are therefore formed from a soft magnetic material.

[0083] Suitable soft magnetic materials for the coil core 25 and back iron 22 are, for example, ferromagnetic or ferrimagnetic materials, i.e., iron, nickel iron, cobalt iron, silicon iron, or mu-metal. In this case, it is preferable that the stator 2, including the coil core 25 and back iron 22, is designed from sheet metal, i.e., as a stator sheet laminate consisting of multiple stacked thin sheet metal elements.

[0084] The coil core 25 and back iron 22 may further consist of pressed and subsequently sintered granules of the aforementioned materials. The metal granules are preferably embedded in a plastic matrix such that they are at least partially insulated from one another, thereby minimizing eddy current losses. Therefore, soft magnetic composites consisting of electrically insulated and compressed metal particles are also suitable for stators. In particular, such soft magnetic composites, also known as SMCs (Soft Magnetic Composites), may consist of iron powder granules coated with an electrically insulating layer. These SMCs are then formed into the desired shape in a powder metallurgy process.

[0085] During the operation of the magnetic levitation device 1, the magnetically effective core 31 of the rotor 3 interacts with the stator 2, allowing the rotor 3 to be magnetically levitated without contact with the stator 2, and preferably, to be magnetically rotated without contact around the axial direction A. In this case, it is particularly advantageous that the same winding 61 that thereby magnetically levitates the rotor 3 also works to generate torque in the rotor 3. Therefore, preferably, the three degrees of freedom of the rotor 3, namely the position and rotation of the rotor in the radial plane E, can be actively adjusted. With respect to the axial deviation of the core 31 from the radial plane E in the axial direction A, the magnetically effective core 31 of the rotor 3 is passively magnetically stabilized by magnetoresistive force, i.e., the axial deviation of the core cannot be controlled. The magnetically effective core 31 of the rotor 3 is also passively magnetically stabilized with respect to the remaining two degrees of freedom, namely the inclination with respect to the radial plane E perpendicular to the desired axis of rotation. Therefore, due to the interaction between the magnetically effective core 31 and the coil core 25, 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), and actively magnetically levitated in the radial plane (2 degrees of freedom).

[0086] As is generally the case, active magnetic levitation is also referred to in the framework of this application as magnetic levitation that can be actively controlled or regulated by an electromagnetic field generated, for example, by a concentrated winding 61. Passive magnetic levitation or passive magnetic stabilization is not controllable or regulated. Passive magnetic levitation or passive magnetic stabilization is based on a magnetic resistance force that returns the rotor 3 to the desired position, for example, when the rotor 3 is deviated from the desired position, i.e., when the rotor is misaligned or deviated in the axial direction A, or when the rotor is tilted.

[0087] In the magnetic levitation device 1, in contrast to conventional magnetic bearings, magnetic levitation and the generation of torque that selectively acts on the rotor are achieved by an electromagnetic rotating field. To generate a combination of magnetic levitation force and torque that rotates the rotor 3 around the axial direction A, it is possible to place just one concentrated winding 61 on each longitudinal leg 26, as shown in Figure 1.

[0088] On the other hand, an embodiment is also possible in which two distinct winding systems are provided to generate a combination of magnetic levitation force and torque for rotating the rotor 3. For example, two concentrated windings, positioned adjacent to each other with respect to the axial direction A, are respectively located at the longitudinal legs. One of these two windings belongs to the first of the two winding systems, and the other belongs to the second of the two winding systems.

[0089] In the embodiment shown in Figure 1, in which each coil core 25 has exactly one concentrated winding 61, the current value required for levitation and the current value required for torque generation are both determined, for example, by the control unit 40 and added or superimposed by calculations, for example, using software. The resulting total current is then applied to each concentrated winding 61.

[0090] For better understanding, the back iron 22 is shown separately from the coil core 25 in Figure 3. The back iron 22 is designed to be substantially ring-shaped and, in the assembled state, extends radially inward along the first end 261 of the longitudinal leg 26 (see also Figure 1). The back iron 22 is preferably designed from sheet metal. In the sheet metal embodiment, the back iron 22 consists of several thin elements stacked parallel to each other in the axial direction. In this case, all elements are designed to be substantially ring-shaped and identical in thickness.

[0091] The back iron 22 has a plurality of flat sections 222 on its radially circumferential surface, which are designed to be planar, i.e., not curved. When the stator 2 is assembled, one first end 261 of the longitudinal legs 26, which preferably have a rectangular profile, is in contact with each of these flat sections 222. The planar design of the flat sections 222 ensures a wide contact surface between the back iron 22 and the longitudinal legs 26 of the coil core 25, resulting in particularly good conduction of magnetic flux or very low magnetic resistance at the transition between the back iron 22 and the longitudinal legs 26. The flat sections may also be arranged in separate segments 225, which are positioned in grooves of the back iron 22. The grooves are dimensioned so that the separate segments 225 are flush with the rest of the back iron 22.

[0092] The number of flat sections 222 is the same as the number of coil cores 25, that is, there are preferably six flat sections 222, and the flat sections are preferably distributed at equal intervals along the outer circumference of the back iron 22.

[0093] Furthermore, one or more vents or vent recesses 223 can be provided in the back iron 22, extending completely through the back iron 22 in the axial direction A. Air can escape through the vent recesses 223, for example, when filling the housing 20 with a thermally conductive potting compound.

[0094] The magnetic levitation device 1 includes a plurality of magnetic field sensors 8 (see also Figure 7) arranged around the cup-shaped recess 211 when the magnetic levitation device 1 is assembled, in order to determine the current position of the rotor 3 within the cup-shaped recess 211. The magnetic field sensors 8 are sensors that can measure magnetic fields. In particular, the following sensor types are suitable as magnetic field sensors 8: Hall sensors, magnetoresistive sensors, or GMR sensors (GMR: giant magnetoresistance). Using the magnetic field sensors 8, the current position of the rotor 3 within the cup-shaped recess 211 of the containment can 21 or in the radial plane E can be determined by a method known to itself.

[0095] According to a particularly preferred embodiment shown in Figure 7, all magnetic field sensors 8 are arranged on a circuit board 7 and are signal-connected to the circuit board 7 via electrical connection parts 81, thereby allowing all magnetic field sensors 8 to be controlled via the circuit board 7, and the signals measured by the magnetic field sensors 8 can be received and processed via the circuit board 7 or transmitted to, for example, a control device 40.

[0096] The circuit board 7 is positioned between one winding 61 and the other lateral leg 27 with respect to the axial direction A. The retaining device 9 is also shown in Figure 7 and is designed to house the circuit board 7. Preferably, the circuit board 7 can be attached to the retaining device 9 by, for example, a number of screws 75 (see Figure 9).

[0097] The circuit board 7 is preferably designed as an electronically printed circuit board (PCB). The magnetic field sensor 8 and the electrical connection 81 are attached to the circuit board 7, for example, by soldered connections. Furthermore, such components used for controlling the magnetic field sensor and / or evaluating the measurement signal determined by the magnetic field sensor 8 can be provided on the circuit board 7.

[0098] The circuit board 7 is designed to be substantially ring-shaped and is positioned parallel to the radial plane E. As can be seen in Figure 7, the circuit board 7 is designed to have ring-segment-shaped openings 74 rather than being a closed ring, so that the circuit board 7 has two ends when viewed circumferentially. Preferably, the circuit board 7 is positioned radially inward with respect to the longitudinal legs 26 of the coil core 25, so that the magnetic field sensors 8 are positioned around the cup-shaped recesses 211 of the containment can 21. Particularly preferably, the magnetic field sensors 8 are positioned equally spaced on the circuit board 7 with respect to the circumferential direction.

[0099] The circuit board 7 further comprises an electrical connection element 76 that connects the circuit board 7 to the control device 40, thereby allowing the control device 40 and the circuit board 7 to exchange voltage or current via the electrical connection element 76. The electrical connection element 76 is preferably designed as a flexprint. The electrical connection element 76 can, of course, also be designed in other ways, such as a cable, cable bundle, or flat ribbon cable.

[0100] As already mentioned, the magnetic levitation device 1 further includes a holding device 9. The holding device 9 provides a particularly simple but precise mounting of the magnetic levitation device 1, and highly precise positioning of the magnetic field sensor 8 relative to the cup-shaped recess 211 in which the rotor 3 is positioned in operation.

[0101] The retaining device 9 is described below with reference to several drawings. Figure 5 shows the retaining device 9 in a perspective view, viewed from the direction of the first end 261 of the longitudinal leg 26. As shown in Figure 1, the viewing direction is therefore directed from below towards the retaining device 9. Figure 6 shows the retaining device 9 in a perspective view, viewed in the opposite direction to the viewing direction in Figure 5. As shown in Figure 1, the viewing direction in Figure 6 is therefore directed from above towards the retaining device 9. Both Figures 5 and 6 show the retaining device 9 together with the circuit board 7 placed inside it. Figure 8 is a cross-sectional view of the retaining device 9 with the circuit board 7 inserted. For better understanding, Figure 9 also shows an enlarged view of detail I in Figure 8.

[0102] The retaining device 9 is designed to be substantially plate-shaped and ring-shaped and includes a number of notches 91 for receiving the lateral legs 27 of the coil core 25. There is exactly one notch 91 for each lateral leg 27, such that the number of notches 91 is equal to the number of coil cores 25. The retaining device 9 is inserted into the containment can 21 (see Figure 1) and extends from the bottom of the containment can 21 axially A to the lower edge shown in Figure 1, which is positioned above the windings 61 axially A as shown.

[0103] The retaining device 9 is designed in a ring shape so that it can be positioned around the cup-shaped recess 211 of the containment can 21, i.e., the cup-shaped recess 211 is surrounded radially outward by the retaining device 9.

[0104] The retaining device 9 has an axial edge region 92 having an outer diameter smaller than the rest of the retaining device 9. As shown in Figure 6, this axial edge region 92 is the upper axial edge region. With respect to axial A, the axial edge region 92 terminates at a projection 93 where the outer diameter of the second retaining device 9 increases. Embodiments with smaller diameter axial edge regions 92 and projections 93 serve to ensure that the containment can 21 can surround the retaining device 9 radially outward. This can be seen particularly in Figure 1. The containment can 21 has a radially outer edge 212 that surrounds the axial edge region 92 of the second retaining device 9 in its assembled state. The radially outer edge 212 is designed to have a length with respect to axial A that extends up to the projection 93.

[0105] The retaining device 9 is preferably formed from plastic, particularly preferably from a plastic that can be lowered by injection molding. The retaining device 9 is therefore preferably designed as an injection-molded part. Suitable plastics for the manufacture of the retaining device 9 are, for example, acrylonitrile butadiene styrene (ABS), polyamide (nylon, PA), polypropylene (PP), or fiber-reinforced polypropylene.

[0106] The holding device 9 acts as both a holder for the circuit board 7 and a holder for the magnetic field sensor 8, which allows the magnetic field sensor 8 to be positioned very precisely in the cup-shaped recess 211. For this purpose, a cavity 95 is provided in each holding device 9 for each magnetic field sensor 8, with its boundary defined radially by an inner wall 951 and an outer wall 952, allowing the magnetic field sensor 8 to be pressed into the cavity 95, which is dimensioned such that the inner wall 951 and outer wall 952 are flush with the magnetic field sensor 8. This is best seen in Figure 9.

[0107] In this substantial embodiment, the inner wall 951 and outer wall 952 of the cavity 95 are positioned flat with respect to the magnetic field sensor 8. This is because the position of the magnetic field sensor 8 relative to the cup-shaped recess 211 is known with very high precision. The magnetic field sensor 8 is preferably designed to be rectangular. The cavity 95 is dimensioned so that the magnetic field sensor 8 can be fully inserted into the cavity 95 with respect to axial A. Thus, the cavity 95 forms a pocket for the magnetic field sensor 8, which is at least the same depth with respect to axial A as the extension of the magnetic field sensor 8 in axial A. The width of this pocket in the radial direction, i.e., the radially measured distance between the inner wall 951 and the outer wall 952, is dimensioned to correspond to the radial extension of the magnetic field sensor 8, thereby allowing the magnetic field sensor 8 to be pushed into the cavity 95 axially, thereby positioning the inner wall 951 and outer wall 952 of the cavity 95 flat with respect to the magnetic field sensor 8.

[0108] In this embodiment, the magnetic field sensor 8 is surrounded by the cavity 95 on three sides, so that on the one hand, the position of the magnetic field sensor 8 can be determined with very high precision, and on the other hand, the magnetic field sensor 8 located in the cavity 95 is also very well protected.

[0109] To facilitate the insertion of the magnetic field sensor 8 into the cavity 95 during assembly, it may be advantageous to design the inner wall 951 and / or outer wall 952 at a slight angle with respect to the axial direction such that the cavity 95 is designed to be slightly conical when viewed in axial direction A, thereby causing the cavity 95 to taper upward with respect to the illustration in Figure 9.

[0110] Furthermore, it is preferable that each magnetic field sensor 8 be positioned as close as possible to the cup-shaped recess 211. For this purpose, the inner diameter of the retaining device 9 is sized to be the same as or only slightly larger than the outer diameter DA (Figure 11) of the cup-shaped recess 211 of the containment can 21. Thus, in the assembled state, the wall portion of the retaining device 9 that forms the inner wall 951 of the cavity 95 is positioned relative to the cup-shaped recess 211 of the containment can 21. Viewed radially, the inner wall 951 that defines the boundary of the cavity 95 is therefore positioned between the cup-shaped recess 211 of the containment can 21 and the magnetic field sensors 8, respectively.

[0111] Since the magnetic field sensors 8 are preferably arranged at equal intervals on the circuit board 7 with respect to the circumferential direction, the six cavities 95 for the six magnetic field sensors 8 are also preferably arranged at equal intervals with respect to the circumferential direction of the holding device 9. Particularly preferably, exactly one cavity 95 is placed between two adjacent notches 91 in the circumferential direction. In the assembled state, each magnetic field sensor 8 is therefore placed between two adjacent coil cores 25 in the circumferential direction.

[0112] With respect to the highest possible accuracy of the position of the magnetic field sensor 8 relative to the cup-shaped recess 211, it is preferable to provide separate guide elements 96 for each cavity 95, forming an inner wall 951 or an outer wall 952 that defines the boundary of the cavity 95.

[0113] Figure 9 shows an embodiment in which guide elements 96 form an outer wall 952 for the cavity 95. For better understanding, Figure 10 further shows a perspective view of a separate guide element 96 of Figure 9. Since such separate guide elements 96 are provided for each cavity 95, there are therefore six such guide elements 96 in this embodiment. The separate guide elements 96 are separate components, i.e., separate from the retaining device 9, and are only pressed into the retaining device 9 after the retaining device 9 is manufactured, thereby forming the cavity 95 for the magnetic field sensor 8. Since the guide elements 96 are separate components, they can be manufactured with very high precision, which is advantageous for the precision of the position of the magnetic field sensor 8. In addition, the separate guide elements 96 make it particularly easy to fit the dimensions of the cavity 95 to each magnetic field sensor 8.

[0114] As can be best seen in Figure 9, each separate guide element 96 has an L-shaped profile. Each separate guide element 96 has a bottom 961 (Figure 10) that forms the short leg of the L and a side wall 962 that forms the long leg of the L. The bottom 961 of the guide element 96 also forms the bottom of the cavity 95. The side wall 962 of the guide element 96 forms the outer wall 952 that defines the boundary of the cavity 95. The side wall 962 includes two parallel guides 963, and the magnetic field sensor 8 is pushed between those guides 963 when the guide element 96 is inserted into the holding device 9. The two parallel guides 963 have a distance D1 from each other that corresponds to the corresponding extension of the magnetic field sensor 8, thereby allowing the magnetic field sensor 8 to be pushed between the two guides 963 and guided by the guides 963 in the process. The two guides 963 have a length L which is the axial extension of the guide 963 in the inserted state. The length L is sized to be at least the same as the corresponding dimension of the magnetic field sensor 8 so that the magnetic field sensor 8 does not protrude beyond the guide element 96 with respect to the axial direction A.

[0115] As previously mentioned, the retaining device 9 in the embodiment described herein is designed to accommodate a circuit board 7 on which a magnetic field sensor 8 is located. For this purpose, the retaining device 9 includes a ring-shaped edge 97 (Figure 9) on which a shoulder 98 is provided, the shoulder 98 being positioned radially inward with respect to the edge 97. The shoulder 98 is designed and positioned so that the circuit board 7 can be placed on the shoulder 98 and is positioned relative to this shoulder 98. Selectively, the circuit board 7 can be attached to the shoulder 98 and, by extension, the retaining device 9 by a number of screws 75. Preferably, the edge 97 is designed to protrude beyond the circuit board 7 with respect to the axial direction A. This has the advantage that potting compound can be poured over the entire retaining device 9 and the circuit board is completely covered by the potting compound.

[0116] Figure 11 shows a cross-sectional view of the stator 2 containment can 21 of an embodiment of a magnetic levitation device, with the cross-section created in the axial direction A.

[0117] The containment can 21, which has a cup-shaped recess 211, is preferably designed as a single unit. The containment can 21 is preferably formed from plastic, particularly preferably from a plastic that can be processed by injection molding. Therefore, the containment can 21 is preferably designed as an injection-molded part. Suitable plastics for the manufacture of the containment can 21 include, for example, acrylonitrile butadiene styrene (ABS), polyamide (nylon, PA), polypropylene (PP), polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), polyvinyl chloride (PVC), polybutylene terephthalate (PBT), polyimide (PI), polyether ketone, polysuccinimide (PSI), polyphthalamide (PPA), or polyetheretherketone (PEEK).

[0118] The containment can 21 includes a cup-shaped recess 211 into which the rotor 3 can be inserted, and a radial outer edge 212 that surrounds the axial edge area 92 of the retaining device 9 when assembled.

[0119] The following describes how a magnetic levitation device can be assembled in a very simple manner. Assembly can be carried out, for example, as follows: Insert the sensor board 7, on which the magnetic field sensors 8 are positioned and mounted, into the holding device 9. To do this, each of the magnetic field sensors 8 is first pushed into one of the cavities 95, and the circuit board 7 is placed on the shoulder 98 of the holding device 9. Selectively, the circuit board 7 is attached to the holding device 9 by screws 75.

[0120] Next, the first potting compound is poured completely into the holding device 9 so that the circuit board 7 is completely covered by the first potting compound. The first potting compound is preferably a flexible potting compound. A flexible potting compound means a potting compound having a Shore hardness D of less than 40. For example, silicone or polyurethane is suitable as the first potting compound. Strong and frequent temperature fluctuations can occur during the operation of the magnetic levitation device, especially in the area of ​​the holding device 9 where the magnetic field sensor 8 is located. A flexible potting compound is more resistant to such fluctuations. Therefore, a flexible potting compound is preferred for pouring into the holding device 9.

[0121] The coil core 25 is passed through the notch 91 and concentrated winding 61 of the retaining device 9. The magnetic back iron 22 is positioned between the first ends 261 of the longitudinal legs 26. The coil core 25, with the retaining device 9, back iron 22, and concentrated winding 61 positioned, is inserted into the stator housing 101 of the housing 10 in the first mounting direction in the axial direction A (from the left as shown in Figure 2). In this step, the electrical connection element 76 is passed through the stator housing 101 into the control housing 102 parallel to the longitudinal legs 26 of the coil core 25.

[0122] Once the retaining device 9, winding 61, back iron 22, and coil core 25 are positioned within the stator housing 101 of the housing 10, the containment can 21 is placed on the housing 10 and the seal 201 is placed between the containment can 21 and the housing 10, thereby connecting them to the housing 10 in a sealed, preferably hermetically sealed, state.

[0123] Next, a thermally conductive potting compound is poured into the housing 10 of the magnetic levitation device 1. Preferably, a second potting compound that is sufficiently thermally conductive and different from the first potting compound is used for this purpose. The second thermally conductive potting compound is preferably harder than the first potting compound. The second thermal potting compound should have particularly good thermal conductivity to quickly and reliably dissipate the heat generated in the operating state into the housing, which is then dissipated from the housing mainly by convection. Suitable second thermally conductive potting compounds include, for example, polyurethane, epoxy resin, acrylic resin, or polyester.

[0124] After pouring the second potting compound into the stator housing 101 of housing 10, the control unit 40 is inserted into the control housing 102 of housing 10 in a second mounting direction, the second mounting direction being opposite to the first mounting direction. The control unit 40 is therefore inserted into the control housing 102 from the right side, as shown in Figure 2. The electrical connection element 76 is connected to the control unit 40.

[0125] When the control unit 40 is positioned in the control housing 102 of the housing 10, the housing cover 11 is positioned on the housing 10 and connected to the housing 10 in a sealed state, preferably an airtight seal, and the sealing element 105 is positioned between the housing 11 and the housing 10. The housing cover 11 is attached to the housing 10 by, for example, a number of screws 111 (Figure 1).

[0126] Selectively, for example, in applications using highly corrosive, highly erosive, or explosive fluids, the potting compound can also be poured into the control housing 102 of the housing 10. If the control housing is also poured, this is done before the housing cover 11 is placed on the housing 10 and securely connected to the housing 10.

[0127] Furthermore, the present invention proposes a centrifugal pump 100 for transporting fluids, characterized in that the centrifugal pump 100 includes a magnetic levitation device 1 and a rotor 3, and the magnetic levitation device 1 is designed in accordance with the present invention. The magnetic levitation device 1 is designed to generate a torque acting on the rotor 3 that drives the rotation of the rotor 3 about the axial direction A, in addition to non-contact magnetic levitation of the rotor 3.

[0128] Figure 12 is a schematic cross-sectional view in the axial direction A, showing an embodiment of the centrifugal pump according to the present invention, the whole of which is indicated by reference numeral 100. For a deeper understanding and a clearer overview, the housing 10 and the containment can 21 are not shown in Figure 12.

[0129] The centrifugal pump 100 includes a pump unit 50 comprising a pump housing 51 including an inlet 52 and an outlet 53 for the fluid to be conveyed, and a rotor 3 located within the pump housing 51 and including a plurality of vanes 54 for conveying the fluid. The pump unit 50 is designed so that it can be inserted into the containment can 21 of the stator 2, thereby surrounding the magnetically effective core 31 of the rotor 3 with the end faces 271 of the lateral legs 27.

[0130] Since the rotor 3 is both the rotor 3 for magnetic levitation and the rotor 3 of the centrifugal pump 100 through which the fluid is transported, it is advantageous for the rotor 3 to be designed as an integrated rotor. This embodiment as an integrated rotor offers the advantages of a very compact and space-saving design.

[0131] The stator 2 is housed in a housing 10 (not shown in Figure 12), which is preferably designed as a sealed housing 10 together with the containment can 21. The control unit 40 is also preferably housed in the housing 10, but not necessarily. The housing 10 is preferably filled with a potting compound, such as epoxy resin, acrylic resin, polyester, or polyurethane, so that all components housed within the housing 10 are surrounded by the potting compound.

[0132] The pump unit 50 is positioned in a cup-shaped recess 211 of the containment can 21 (not shown in Figure 12), so that the rotor 3 located within the pump housing 51 is surrounded by this cup-shaped recess 211, and the magnetically effective core 31 of the rotor 3 is positioned between the lateral legs 27 of the coil core 26.

[0133] The pump housing 51 is preferably secured to the housing 20 by a plurality of screws (not shown).

[0134] The rotor 3 includes a plurality of vanes 54 for conveying fluid. For example, in the embodiment described herein, there are a total of four vanes 54, and this number is an exemplary feature. The rotor 3 further includes a jacket 38, which surrounds and preferably seals the magnetically effective core 31 of the rotor 3 so that the magnetically effective core 31 of the rotor 3 does not come into contact with the fluid being conveyed. All the vanes 54 are located in the jacket 38 and are spaced equally apart with respect to the circumferential direction of the rotor 3. Each vane 54 extends radially outward and is connected to the jacket 38 in a torque-preventing manner. The vanes 54 may be separate components that are later fixed to the jacket 38. Of course, it is also possible that all the vanes 54 are an integral part of the jacket 38, i.e., the jacket 38 is designed as a single unit with all the vanes 54. The rotor 3, equipped with vanes 54, forms the wheel or impeller of the centrifugal pump 100, through which one or more fluids are applied.

[0135] Depending on the terminology, the pump housing 51 and jacket 38 and vanes 54 of the pump unit 50 are preferably formed from one or more plastics. Suitable plastics include polyethylene (PE), low-density polyethylene (LDPE), ultra-low-density polyethylene (ULDPE), ethylene vinyl acetate (EVA), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polypropylene (PP), polyurethane (PU), polyvinylidene fluoride (PVDF), acrylonitrile butadiene styrene (ABS), polyacrylic polycarbonate (PC), polyether ether ketone (PEEK), or silicone. For many applications, polytetrafluoroethylene (PTFE), known by the trademark name Teflon, and perfluoroalkoxy polymers (PFA) are also suitable as plastics.

[0136] The magnetic levitation device 1 according to the present invention is also suitable for devices other than centrifugal pumps, such as mixing devices for mixing fluids, stirring devices for mixing fluids in a tank, fans, or devices for supporting and rotating wafers in semiconductor manufacturing, for example.

Claims

1. A magnetic levitation device for non-contact magnetic levitation of a rotor (3), comprising a disk-shaped or ring-shaped magnetically effective core (31), wherein the magnetic levitation device has a stator (2) comprising a plurality of coil cores (25), each of which has a longitudinal leg (26) extending axially (A) from a first end (261) to a second end (262), and a frontal portion positioned at the second end (262) of the longitudinal leg and The stator (2) includes transverse legs (27) extending radially perpendicular to the axial direction (A), and at least one concentrated winding (61) is provided on each of the longitudinal legs (26), the winding surrounding each of the longitudinal legs (26), the stator (2) further has a cup-shaped recess (211) into which the rotor (3) can be inserted, the cup-shaped recess (211) is located at the axial end of the stator (2) A magnetic levitation device for non-contact magnetic levitation of a rotor (3), wherein the lateral legs (27) are arranged around the cup-shaped recess (211), and a plurality of magnetic field sensors (8) for determining the position of the rotor (3) are arranged around the cup-shaped recess (211), wherein a ring-shaped holding device (9) having a cavity (95) for each of the magnetic field sensors (8) is provided for the magnetic field sensors (8), the cavity being defined radially by an inner wall (951) and an outer wall (952), the magnetic field sensors (8) being able to be pushed into the cavity (95), and the cavity (95) being sized such that the inner wall (951) and the outer wall (952) are positioned flat with respect to the magnetic field sensors (8).

2. The magnetic levitation device according to claim 1, wherein a circuit board (7) is positioned between the winding (61) and the lateral legs (27) with respect to the axial direction (A), all of the magnetic field sensors (8) are positioned on the circuit board, and the second holding device (9) is designed to house the circuit board (7).

3. The magnetic levitation device according to claim 2, wherein the holding device (9) has a ring-shaped edge (97) on which a shoulder (98) is provided, the shoulder (98) is arranged radially inward with respect to the edge (97), and the circuit board (7) is arranged relative to the shoulder (98).

4. The magnetic levitation device according to claim 3, wherein the edge portion (97) is designed to protrude beyond the circuit board (7) in the axial direction (A).

5. The magnetic levitation device according to any one of claims 1 to 4, wherein the holding device (9) has separate notches (91) for each of the coil cores (25), the notches enclosing the coil cores (25) and accommodating the lateral legs (27) of the coil cores (25).

6. The magnetic levitation device according to claim 5, wherein each of the cavities (95) is located between two adjacent notches (91) in the circumferential direction.

7. A magnetic levitation device according to any one of claims 1 to 6, wherein exactly six of the coil cores (25) are provided.

8. A magnetic levitation device according to any one of claims 1 to 7, comprising exactly six magnetic field sensors (8) preferably arranged at equal intervals around the cup-shaped recess (211).

9. The magnetic levitation device according to any one of claims 2 to 8, wherein the holding device (9) is filled with a first potting compound such that the circuit board (7) is completely covered by the potting compound.

10. A magnetic levitation device according to any one of claims 1 to 9, wherein a separate guide element (96) is provided for each of the cavities (95), the guide elements forming the inner wall (951) and the outer wall (952) that define the boundaries of the cavities (95).

11. The magnetic levitation device according to any one of claims 1 to 10, wherein the stator (2) has a confinement can (21) that forms the axial end of the stator (2), the confinement can (21) has a cup-shaped recess (211) into which the rotor (3) can be inserted, and the confinement can (21) surrounds the second holding device (9) radially outward.

12. A magnetic levitation device according to any one of claims 1 to 11, comprising a housing (10) including a stator housing (101) and a control housing (102) arranged adjacent to each other with respect to the axial direction (A), wherein the stator housing (101) is designed to house the coil core (25) in which concentrated windings (61) are arranged, and the control housing (102) is designed to house a control unit (40) for controlling the windings (61) for generating an electromagnetic field and supplying electrical energy to the windings (61).

13. The magnetic levitation device according to claim 12, wherein the housing (10) is designed so that the coil core (25) on which the concentrated winding (61) is arranged can be inserted into the stator housing (101) in a first mounting direction in the axial direction (A), and the control unit (40) can be inserted into the control housing (102) in a second mounting direction, and the first mounting direction is oriented in the opposite direction to the second mounting direction.

14. The magnetic levitation device according to any one of claims 1 to 13, wherein the stator (2) is designed to generate torque that can magnetically drive the rotor (3) without contact for rotation about the axial direction (A).

15. A centrifugal pump for transporting a fluid, wherein the centrifugal pump comprises a magnetic levitation device (1) as described in claim 14 and a rotor (3) having a magnetically effective core (31), wherein the rotor (3) can be inserted into a cup-shaped recess (211) of a containment can (21), and the rotor (3) is designed as the rotor (3) of the centrifugal pump.

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