Magnetic levitation device and centrifugal pump

Abstract

To propose a magnetic levitation device in which the position of a rotor can be determined reliably and with very high accuracy by magnetic field sensors, and a centrifugal pump with such a magnetic levitation device.SOLUTION: There is proposed a magnetic levitation device 1 for contactless magnetic levitation of a rotor 3 including a disk-shaped or ring-shaped magnetically effective core 31. The magnetic levitation device 1 includes a stator 2 which includes a plurality of coil cores 25. Each of the coil cores includes a longitudinal leg 26 extending from a first end 261 in an axial direction A to a second end 262, and a transverse leg 27 which is arranged at the second end 262 of the longitudinal leg and which extends in a radial direction perpendicular to the axial direction A, at least one concentrated winding 61 being provided at each longitudinal leg 26. The transverse legs 27 are arranged around a cup-shaped recess 211, and a plurality of magnetic field sensors for determining the position of the rotor 3 is arranged around the cup-shaped recess 211.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a magnetic levitation device described in the preamble of an 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 have very high requirements regarding 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 substance pumps or mixers in the semiconductor industry.

[0003] Such a magnetic bearing device is used in the biotechnological industry, for example, together with a bioreactor, in a centrifugal pump that transports a fluid, for example, into or out of a bioreactor, or in a mixing device that mixes fluids within a 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, for example, a wafer.

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

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

[0006] A characteristic peculiar to the temple structure is that the stator of the magnetic bearing device includes a plurality of coil cores, and each of the coil cores includes longitudinal legs that extend axially from a first end to a second end. Here, the axial direction refers to the direction defined by the desired rotation axis of the rotor supported by the magnetic bearing device. The desired rotation axis is the rotation axis around which the rotor rotates when the rotor is in an operating state, centered with respect to the stator, and in a non-inclined posture. In addition to the longitudinal legs, each coil core is provided with transverse legs that are arranged at the second end of the longitudinal legs and extend radially, usually inward. Here, the radial direction is perpendicular to the axial direction. The transverse legs thus extend substantially perpendicular to the longitudinal legs. Each coil core has an L shape, and the transverse legs form the short legs of the L shape. Then, the rotor to be supported is arranged between the transverse legs.

[0007] The fact that the plurality of longitudinal legs extending axially reminds one of the columns of a temple is the origin of the name of this structure.

[0008] In one design, the stator of the magnetic bearing device includes, for example, six coil cores that are circularly and equally spaced around the periphery of a cup-shaped recess into which the rotor can be inserted. The first ends of the longitudinal legs are usually circumferentially connected by a back iron that acts to conduct magnetic flux. The rotor to be supported includes a magnetically effective core, such as a permanent magnet disk or a permanent magnet ring, and is arranged between the radially inner ends of the transverse legs and rotates about the axial direction in an operating state. Here, the rotor is magnetically supported without contacting the stator.

[0009] In such a magnetic bearing device, it is not necessarily true that the magnetically effective core of the rotor needs to be designed by means of permanent magnets. Designs are also known in which the magnetically effective core of the rotor is designed by a method without permanent magnets, i.e., without permanent magnets. In this case, the magnetically effective core of the rotor is designed, for example, by a ferromagnetic method and is made of, for example, iron, nickel iron, cobalt iron, silicon iron, mu-metal, or another ferromagnetic material.

[0010] Furthermore, a design in which the magnetically effective core of the rotor includes both a ferromagnetic material and a permanent magnetic material is possible. For example, permanent magnets can be disposed or inserted into a ferromagnetic matrix. Such a design is advantageous, for example, when it is desired to reduce the cost of a large rotor by saving permanent magnetic materials.

[0011] The longitudinal legs carry the windings and generate the electromagnetic fields necessary to magnetically support the rotor in a non-contact manner. The windings are designed, for example, such that one concentrated winding is wound around each longitudinal leg, i.e., the coil axes of each concentrated winding all extend axially. Here, it is a typical template structure that the coil axes of the concentrated windings extend axially and the concentrated windings are not arranged in the radial plane in which the rotor or the magnetically effective core of the rotor is supported in the operating state.

[0012] It is possible to design such that exactly one concentrated winding is arranged on each longitudinal leg. In other designs, a plurality of, for example, exactly two concentrated windings are provided on each longitudinal leg. It is also possible to design such that the windings are provided so as to be wound around two circumferentially adjacent longitudinal legs, and thus both of these two adjacent longitudinal legs are located inside the concentrated winding.

[0013] It is very important that a reliable and safe non-contact magnetic bearing of a rotor can know the current position of the rotor in the radial plane with high accuracy in each case and can adjust the position of the rotor in the radial plane to a desired position. To determine the position of the rotor, for example, from WO 2014 / 036419, it is known to arrange a plurality of magnetic field sensors, such as Hall sensors, in a magnetic bearing device so as to be arranged around the magnetically effective core of the rotor. Then, the current position of the rotor is 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, that is, for example, the stator magnetic field, it is often very difficult to determine the exact position of the rotor in the radial plane from the signals of the magnetic field sensors.

Prior Art Documents

Patent Documents

[0014]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[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 magnetically effective core on a ring or disk, which can reliably and very accurately determine the position of the rotor by a magnetic field sensor starting from this state of the art. Furthermore, an object of the present invention is to propose a centrifugal pump provided with such a magnetic levitation device.

Means for Solving the Problems

[0016] The subject matter of the present invention that meets this object is characterized by the features of the independent patent claims.

[0017] Accordingly, according to the present invention, there is proposed a magnetic levitation device 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 including a plurality of coil cores, each of the coil cores including a longitudinal leg extending axially from a first end to a second end and a transverse leg disposed at the second end of the longitudinal leg and extending in a radial direction perpendicular to the axial direction, at least one concentrated winding being provided on each longitudinal leg, the winding surrounding each longitudinal leg, the stator having a cup-shaped recess into which the rotor can be inserted, the cup-shaped recess being disposed at an axial end of the stator, the transverse legs being disposed around the cup-shaped recess, and a plurality of magnetic field sensors for determining the position of the rotor being disposed around the cup-shaped recess. A ring-shaped holding device for the magnetic field sensors is provided, the ring-shaped holding device having a cavity for each magnetic field sensor, the cavity being bounded radially by an inner wall and an outer wall, the magnetic field sensor being pushable into the cavity, and the cavity being dimensioned such that the inner wall and the outer wall are disposed flat with respect to the magnetic field sensor.

[0018] By providing a ring-shaped holder having a cavity for each magnetic field sensor dimensioned such that the inner wall and the outer wall are disposed flat with respect to the magnetic field sensor, the position of each magnetic field sensor is known with extremely high accuracy. In particular, the position of the magnetic field sensor relative to the cup-shaped recess is known with high accuracy, which enables a very accurate determination of the position of the rotor in the cup-shaped recess. In particular, the position of each magnetic field sensor is defined only by the position of the cavity and does not depend, for example, on how the magnetic field sensor is soldered to a circuit board or adhered to a structure. Even if the position of the magnetic field sensor is determined by such a connection as soldering or adhesion, this generally results in inaccuracies in the placement, which has an adverse effect on the accuracy of determining the position of the rotor. In embodiments according to the present invention, the soldered or adhered connection does not affect the position of the magnetic field sensor, which results in a very high accuracy in determining the rotor position.

[0019] According to a preferred embodiment, the circuit board is arranged axially between the winding and the lateral leg, all the magnetic field sensors are arranged on the circuit board, and the holding device is designed to accommodate the circuit board. This has the advantage that all the magnetic field sensors can first be connected to the circuit board, whereby electrical connections for controlling the magnetic field sensors and receiving measurement signals are formed on the circuit board. Subsequently, the circuit board with the magnetic field sensors connected is then inserted into the holding device, and the magnetic field sensors are pushed into the cavity. Finally, the circuit board is firmly connected to the holding device, for example by means of screws and / or by a potting compound poured into the holding device.

[0020] Here, it is preferred that the holding device has an annular edge provided with a shoulder, the shoulder being arranged radially inside with respect to the edge, and the circuit board being arranged against the shoulder. This shoulder thereby forms a support for the circuit board so that the circuit board can be arranged in the holding device in a very simple manner.

[0021] Furthermore, it is preferred that the edge is designed to project axially beyond the circuit board. By this means, it is possible to pour a potting compound into the holding device, and the circuit board is completely covered by the embedding resin.

[0022] According to a preferred embodiment, the holding device has a separate notch for each coil core, the notch surrounding the coil core and accommodating the lateral leg of the coil core.

[0023] In this case, it is advantageous if each cavity is arranged between two adjacent notches with respect to the circumferential direction. This enables each magnetic field sensor to be arranged between two adjacent coil cores with respect to 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 therein 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 the operation of the magnetic levitation device, particularly in the region of the holding device in which the magnetic field sensor is disposed, strong and frequent temperature fluctuations can occur. The flexible potting compound is more resistant to such fluctuations. Therefore, 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 therein 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. Therefore, the second thermal potting compound has a higher hardness, particularly a higher Shore hardness D, than the first potting compound.

[0028] Regarding arranging the magnetic field sensor as accurately as possible, it is advantageous for separate guide elements that form the inner or outer walls defining the boundaries of the cavities to be provided for each cavity. Such separate guide elements can usually be manufactured with a much higher precision than the entire holding device, which is typically produced, for example, by injection molding. To form the cavity for the magnetic field sensor, the separate guide elements are axially inserted into the recesses in the holding device provided for this purpose, whereby the separate guide elements then form the inner or outer walls that define the boundaries of the cavity in the radial direction. Preferably, the separate guide elements are connected to the holding device in a form-locking manner, for example, by press-fitting.

[0029] Preferably, the stator has a containment can that forms the axial end region of the starter. The containment can has a cup-shaped recess into which the rotor can be inserted, and the containment can surrounds the holding device radially outward. In this preferred embodiment, the containment can is preferably designed as a separate containment can with a cup-shaped recess. For particular structural reasons, it is preferred that the containment can surrounds a second holding device radially outward. Based on this, the axial end region of the second holding device is arranged within the containment can and is completely surrounded by the containment can when viewed in the circumferential direction.

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

[0031] Furthermore, it is preferred that the containment can is 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 including a stator housing and a control housing arranged adjacent to each other in the axial direction. The stator housing is designed to accommodate a coil core in which concentrated windings are arranged, and the control housing is designed to accommodate a control unit for controlling the windings and supplying electrical energy to the windings for generating an electromagnetic field.

[0033] Preferably, the housing is designed such that a coil core with concentrated windings can be inserted into the stator housing in a first mounting direction in the axial direction and the control unit can be inserted into the control housing in a second mounting direction, where the first mounting direction is oriented in a direction opposite to the second mounting direction. The housing preferably 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 portion having a passage for electrical connection. Therefore, the housing is preferably designed integrally in the circumferential direction.

[0034] According to a particularly preferred embodiment, the stator of the magnetic levitation device is designed to generate a torque capable of magnetically driving a rotor without contact for rotation about the axial direction.

[0035] Furthermore, a centrifugal pump for transporting a fluid is proposed according to the present invention, which includes the magnetic levitation device according to the present invention and a rotor having a magnetically effective core, and the rotor can be inserted into a cup-shaped recess of a closed can, and the rotor is designed as a rotor of a centrifugal pump.

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

[0037] Hereinafter, the present invention will be described in more detail with reference to embodiments and also with reference to the drawings.

Brief Description of the Drawings

[0038]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Mode for Carrying Out the Invention

[0039] FIG. 1 shows a cross-sectional view of an embodiment of a magnetic levitation device according to the present invention, and the whole is 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] FIG. 2 shows, for better understanding, the perspective view of the embodiment of FIG. 1 in the form of an exploded perspective view, and the rotor 3 is not shown in FIG. 2. The magnetic levitation device 1 is designed according to the temple structure and includes a stator 2. The stator 2 includes a plurality of coil cores 25, here six coil cores 25. Each of the coil cores includes a longitudinal leg 26 extending in the axial direction A from a first end 261 to a second end 262, and a transverse leg 27 arranged perpendicular to the longitudinal leg 26 and extending in the radial direction perpendicular to the axial direction A. Each transverse leg 27 is bounded in the radial direction by an end face 271 that forms the pole of the associated coil core.

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

[0042] The magnetic levitation device 1 includes a housing 10, and the coil cores 25 are arranged within the housing 10.

[0043] FIGS. 3 and 4 show, for better understanding, further views of the stator 2 of the embodiment of the magnetic levitation device 1, and the housing 10 is not shown. FIG. 3 shows a perspective view of the stator 2 and the holding device 9 to be described in more detail. Further, FIG. 3 is provided with a back iron 22, and this back iron 22 connects all the first ends 261 of the longitudinal legs 26, that is, the lower ends 261 according to the illustration (FIG. 1), to each other and serves to conduct magnetic flux. The back iron 22 is preferably designed in a ring shape. FIG. 4 shows an exploded perspective view of the coil core 25 with the concentrated winding 61 arranged thereon and the holding device 9.

[0044] The housing 10 is preferably formed from a metallic material, such as aluminum or stainless steel. In order to further enhance the chemical resistance, the housing 10 can be provided with a coating, preferably a plastic coating formed 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 can also be formed from titanium or chrome steel.

[0045] The stator 2 further includes a confinement can 21 having a cup-shaped recess 211 (see also FIG. 11), and a rotor 3 to be levitated can be inserted into the cup-shaped recess 211 (see FIG. 1). The confinement can 21 forms one of the two axial ends of the stator 2 or the magnetic levitation device 1, and according to the illustration in FIG. 1, forms the upper axial end of the stator 2. A housing cover 11 for closing the housing 10 is disposed at the other axial end of the magnetic levitation device 1.

[0046] The confinement can 21 is firmly connected to the housing 10, for example, by a form-locking connection and / or by using an elastic seal 201. Preferably, the confinement can 21 is connected to the housing 10 in a gas-tight manner. The housing cover 11 is firmly connected to the housing 10, for example, by screws 111 (FIG. 1), and a sealing element 105 is selectively disposed 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 a gas-tight manner.

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

[0048] Preferably, the housing cover is formed from plastic. In applications particularly in highly chemically aggressive environments, chemically resistant plastics such as polypropylene are preferred.

[0049] The lateral legs 27 of the coil core 25 are arranged in the containment can 21 such that the end face 271 of the lateral legs 27 is arranged around the periphery of the cup-shaped recess 211.

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

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

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

[0053] Furthermore, a control unit 40 is provided for controlling the winding 61 and supplying electrical energy to the winding 61. The control unit 40 includes, in particular, power electronics for supplying the necessary current to the winding 61, for example an inverter of a rectifier. The control unit 40 is shown in FIGS. 1 and 2. Particularly preferably, the control unit 40 is also arranged inside the housing 10, for example below the first end 261 of the longitudinal leg 26 of the coil core 25 according to the illustration (FIG. 1). The control unit 40 is also preferably encapsulated in a thermally potted compound or coupled to the housing 10 and the back iron 22 and / or the coil core 25 of the 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 particularly recognized in FIGS. 1 and 2, the housing 10 preferably includes two regions that are separate from each other and arranged adjacent to each other with respect to the axial direction A. One region forms the stator housing 101, and the other region forms the control housing 102. The stator housing 101 of the housing 10 is designed to accommodate the coil core 25 in which the winding 61 is arranged, and the control housing 102 is designed to accommodate the control unit 40.

[0055] According to a preferred measure, the housing 10 includes an internally cylindrical cup 13 that is arranged radially inside the winding 61 in the internal space surrounded by the winding 61. The internal cup 13 is connected to the outer wall 15 of the housing 10 via a flange-like protrusion 14. The outer wall 15 forms the radially outer boundary of the housing 10. Particularly preferably, the internal cup 13 and the flange-like protrusion 14 are an integral part of the housing 10. The outer wall 15, the flange-like protrusion 14, and the internal cup 13 are integrally designed as a whole and preferably form an integral housing 10.

[0056] The inner cup 13 and the flange-shaped protrusion 14 separate the area of the housing 10 that forms the stator housing 101 from the area that forms the control housing 102.

[0057] The inner cup 13 connected to the flange-shaped protrusion 14 extends in the axial direction A from the radially inner edge of the flange-shaped protrusion 14 and is arranged radially inside the winding 61 and the back iron 22 in the inner space surrounded by the winding 61, as can be particularly recognized in FIG. 1. In terms of the radial direction, the inner cup 13 is arranged adjacent to the longitudinal leg 26 of the coil core 25 or the winding 61 arranged on the longitudinal leg, so that the inner cup 13 can absorb and dissipate the heat generated by the winding 61 and the coil core 25 particularly well. In terms of the axial direction A, the inner cup 13 extends substantially up to the cup-shaped recess 211 of the enclosure 21.

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

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

[0060] Along with exemplary features, some components of the control unit 40 are shown in FIG. 1. The control unit 40 includes, for example, an electronic component 42, such as an electronic substrate 41 provided with power electronics for controlling a winding 61. For example, the electronic substrate 41 can further include evaluation electronics for evaluating signals from sensors, such as magnetic field sensors, or can function as a communication interface. The circuit board 41 is preferably designed as an electronic print or a PCB (printed circuit board). Further, a connection cable 45 is provided, and the connection cable is connected to the electronic substrate 41 via a cable connection (not shown) or a plug. The connection cable 45 is drawn out from the housing 10 and serves, for example, to supply power to the magnetic levitation device 1. The connection cable 45 is drawn out from the housing 20 by a cable bushing 47 with a sealed design. Preferably, the cable bushing 47 is designed in a gas-tight state.

[0061] The electronic substrate 41 of the control unit 40 is connected to the winding 61 via a connection line (not shown), such as a cable, to control the winding and supply energy to the winding. It should be understood that a feed-through or an opening for passing the connection line is provided between the control housing 102 and the stator housing 101. Such a feed-through can be arranged, for example, in a flange-shaped protrusion 14 or an internal cup 13.

[0062] The electronic substrate 41 is preferably arranged directly on the flange-shaped projection 14, whereby the electronic substrate is arranged relative to the flange-shaped projection 14. In this way, it is possible to dissipate the heat generated in the control unit 40 particularly efficiently via the housing 10. Preferably, the main heat source in the control unit 40, for example, the circuit breaker for the winding 61, is arranged in the region of the electronic substrate 41 arranged 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 substrates, or plugs or connections. These are not shown in FIG. 1 for a clearer overview.

[0064] According to a particularly preferred embodiment, in addition to magnetically levitating the rotor 3 without contact, the stator 2 is designed such that torque can also be applied to the rotor 3 or the magnetically effective core 31 of the rotor 3, and this torque drives the rotor 3 to rotate about the desired axis of rotation. Here, the desired axis of rotation refers to the axis about which the rotor 3 rotates when the rotor 3 is in the operating state, centered with respect to the stator 2 and in a non-tilted posture, as shown in FIG. 1. This desired axis of rotation extends in the axial direction A, that is, in this preferred embodiment, the rotor 3 arranged in the containment can 21 of the stator 2 can be driven to rotate about the axial direction A. Usually, the desired axis of rotation coincides with the central axis of the stator 2 extending in the axial direction A.

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

[0066] It should be understood that the number of the six coil cores 25 is merely an example and is preferred. Of course, embodiments in which the stator 2 includes less than six coil cores 25, such as five, four, or three coil cores 25, or embodiments in which the stator 2 includes more than six coil cores 25, such as seven, eight, or nine coil cores 25, or even more coil cores 25 are also possible.

[0067] The rotor 3 includes a magnetically effective core 31 designed in a ring shape or a disk shape. According to the illustration in FIG. 1, the magnetically effective core 31 is designed as a ring and defines a magnetic center plane. Alternatively, the magnetically effective core 31 can also be designed as a disk. Usually, 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 the operating state, the magnetically effective core 31 is levitated in the radial plane E that stands vertically in the axial direction A. The radial plane is shown in FIG. 1 by a line E that stands vertically with respect to the axial direction A. Therefore, the radial plane E is a plane that stands vertically in the axial direction A and includes the line E.

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

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

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

[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 end face 271 arranged radially outside of the lateral leg 27 of the coil core 25 of the stator 2. Thus, the lateral leg 27 forms a plurality of stator poles, in this case six stator poles. The lateral leg 27 is arranged at the upper end of the longitudinal leg 26 in the radial plane E. Each lateral leg 27 extends radially towards 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 thus the lateral legs 27 arranged in the radial plane E are also located in the magnetic center plane. According to the illustration, the concentrated winding 61 is arranged 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 legs 26, that is, the lower ends 261 (FIG. 1) according to the illustration, are connected to each other by the 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 inwards along all first ends 261 of the longitudinal legs 26 (see, for example, FIG. 1).

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

[0075] In the operating state, these electromagnetic rotating fields are generated by these concentrated windings 61, and the electromagnetic rotating fields can apply an arbitrarily adjustable lateral force in the radial direction to the rotor 3, whereby 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, can be actively controlled or adjusted. Optionally, additional torque is generated on the rotor 3 by these electromagnetic rotating fields.

[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 a magnetic levitation force and, optionally, a 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 as a permanent magnet. For this purpose, the magnetically effective core 31 can include at least one permanent magnet, but can also include a plurality of permanent magnets, or, as in the embodiment described here, can be entirely composed of a permanent magnetic material such that the magnetically effective core 31 is a permanent magnet. The magnetically effective core 31 is magnetized, for example, in the radial direction.

[0078] These ferromagnetic or ferrimagnetic materials that are magnetically hard, i.e., have a high coercive force, are generally called permanent magnets. The coercive force is the magnetic field strength required to demagnetize the material. Within the framework of the present application, a permanent magnet is understood to be a component or material having a coercive force, more precisely a coercive force in a magnetic context exceeding 10000 A / m.

[0079] Embodiments are also possible in which the magnetically effective core 31 is designed without a permanent magnet, i.e., designed without a permanent magnet. The rotor 3 is, in this case, designed, for example, as a magnetoresistive rotor. The magnetically effective core 31 of the rotor 3 is, in this case, formed, for example, from a soft magnetic material. Suitable soft magnetic materials for the magnetically effective core 31 are, for example, ferromagnetic materials or ferrimagnetic materials, i.e., in particular iron, nickel iron, cobalt iron, silicon iron, 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 or inserted into a ferromagnetic matrix. Such embodiments are advantageous, for example, when it is desired to reduce the cost of a large rotor by saving permanent magnetic material.

[0081] Embodiments are also possible in which the rotor is designed according to the principle of a squirrel-cage rotor.

[0082] Both the ring-shaped back iron 22 and the coil core 25 of the stator 2 each function as a magnetic flux conducting element for conducting magnetic flux, and thus are formed from a soft magnetic material.

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

[0084] The coil core 25 and the back iron 22 can further consist of the granulates of the aforementioned materials that are pressed and subsequently sintered. The metal granulates are preferably embedded in a plastic matrix such that the metal granulates are at least partially insulated from each other, whereby eddy current losses can be minimized. Therefore, a soft magnetic composite material consisting of electrically insulated and compressed metal particles is also suitable for the stator. In particular, such soft magnetic composite materials, also referred to as SMC (Soft Magnetic Composites), can consist of iron powder particles coated with an electrical insulation 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, enabling the rotor 3 to be magnetically levitated without contacting the stator 2, and preferably, it can also be magnetically rotated without contacting about the axial direction A. In this case, it is particularly advantageous that the same winding 61 that magnetically levitates the rotor 3 also serves to generate torque on the rotor 3. Therefore, preferably, the three degrees of freedom of the rotor 3, i.e., the position and rotation in the radial plane E of the rotor, can be actively adjusted. Regarding the axial offset 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 magnetic reluctance, i.e., the axial offset of the core cannot be controlled. The magnetically effective core 31 of the rotor 3 is also passively magnetically stabilized regarding the remaining two degrees of freedom, i.e., 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 either passively magnetically levitated or passively magnetically stabilized (a total of three degrees of freedom) against inclination in the axial direction A, and can be actively magnetically levitated in the radial plane (two degrees of freedom).

[0086] As is generally the case, active magnetic levitation is also called magnetic levitation that can be actively controlled or regulated by an electromagnetic field generated, for example, by the concentrated winding 61, even within the framework of this application. Passive magnetic levitation or passive magnetic stabilization cannot be controlled or regulated. Passive magnetic levitation or passive magnetic stabilization is based on, for example, the magnetic restoring force that returns the rotor 3 back to the desired position when the rotor 3 is displaced from the desired position, i.e., for example, when the rotor is displaced 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, the generation of magnetic levitation and, optionally, the torque acting on the rotor are realized by an electromagnetic rotating field. In order to combine and generate the magnetic levitation force and the torque for rotating the rotor 3 about the axial direction A, on the one hand, as shown in FIG. 1, it is possible to arrange exactly one concentrated winding 61 on each longitudinal leg 26.

[0088] On the other hand, embodiments are also possible in which two different winding systems are provided in order to combine and generate the magnetic levitation force and the torque for rotating the rotor 3. For this purpose, for example, exactly two concentrated windings arranged adjacent to each other with respect to the axial direction A are respectively arranged on each longitudinal leg. 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 FIG. 1, with exactly one concentrated winding 61 provided for each coil - core 25, both the current value required for levitation and the current value required for torque generation are determined, for example, by the control unit 40 and added or superimposed, for example, by calculation using software. Then, the total current obtained as a result is applied to each concentrated winding 61.

[0090] The back iron 22 is shown separately from the coil core 25 in FIG. 3 for better understanding. The back iron 22 is substantially designed in a ring shape and, in the assembled state, extends radially inward along the first end 261 of the longitudinal leg 26 (see also FIG. 1). The back iron 22 is preferably designed with sheet metal. In the sheet metal embodiment, the back iron 22 is made up of a plurality of thin elements stacked axially parallel to each other. In this case, all the elements are substantially ring-shaped and are identically designed so that they all have the same thickness.

[0091] The back iron 22 has a plurality of flat portions 222 designed in a planar manner, i.e., without curvature, on its radially outer peripheral surface. In the assembled state of the stator 2, preferably one of the first ends 261 of the longitudinal legs 26 having a rectangular contour abuts against each of these flat portions 222. Due to the planar design of the flat portions 222, a wide contact surface is ensured between the back iron 22 and the longitudinal legs 26 of the coil core 25. As a result, magnetic flux is conducted particularly well or the magnetic resistance is very small at the transition between the back iron 22 and the longitudinal legs 26. The flat portions can also be arranged in separate segments 225, and the separate segments 225 are arranged in the grooves of the back iron 22. The grooves are dimensioned such that the separate segments 225 are flush with the rest of the back iron 22.

[0092] The number of flat portions 222 is the same as the number of coil cores 25, i.e., six flat portions 222 are provided here, and the flat portions are preferably evenly distributed along the outer periphery of the back iron 22.

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

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

[0095] According to a particularly preferred embodiment shown in FIG. 7, all the magnetic field sensors 8 are arranged on the circuit board 7 and are signal-connected to the circuit board 7 via the electrical connection portion 81, whereby all the magnetic field sensors 8 can 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, for example, to the control device 40.

[0096] The circuit board 7 is arranged in the axial direction A between one winding 61 and the other lateral leg portion 27. A holding device 9 is also shown in FIG. 7 and is designed to accommodate the circuit board 7. Preferably, the circuit board 7 can be attached to the holding device 9 by, for example, a plurality of screws 75 (see FIG. 9).

[0097] The circuit board 7 is preferably designed as an electronic print or a PCB (printed circuit board). The magnetic field sensor 8 and the electrical connection portion 81 are attached to the circuit board 7 by, for example, soldered connections. Further, such components used for controlling the magnetic field sensor and / or evaluating the measurement signals 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 arranged parallel to the radial plane E. As can be recognized in FIG. 7, the circuit board 7 is designed to have an opening 74 in the shape of a ring segment rather than as a closed ring, whereby the circuit board 7 has two ends when viewed in the circumferential direction. Preferably, the circuit board 7 is arranged radially inside with respect to the longitudinal legs 26 of the coil core 25, such that the magnetic field sensor 8 is arranged around the cup-shaped recess 211 of the containment can 21. Particularly preferably, the magnetic field sensors 8 are arranged equidistantly on the circuit board 7 with respect to the circumferential direction.

[0099] The circuit board 7 further comprises an electrical connection element 76 for connecting the circuit board 7 to the control device 40, whereby the control device 40 and the circuit board 7 can exchange voltage or current via the electrical connection element 76. The electrical connection element 76 is preferably designed as a flexible printed circuit. The electrical connection element 76 can of course also be designed in another way, for example as a cable, a cable bundle, or a 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 accurate mounting of the magnetic levitation device 1 and a very accurate positioning of the magnetic field sensor 8 with respect to the cup-shaped recess 211 in which the rotor 3 is arranged in the operating state.

[0101] The holding device 9 will be described with reference to a plurality of drawings. FIG. 5 shows the holding device 9 in a perspective view, and the viewing direction is from the direction of the first end 261 of the longitudinal leg 26. According to the illustration of FIG. 1, therefore, the viewing direction is directed towards the holding device 9 from below. FIG. 6 shows the holding device 9 in a perspective view, and the viewing direction is opposite to that of FIG. 5. According to the illustration of FIG. 1, therefore, the viewing direction of FIG. 6 is directed towards the holding device 9 from above. Both FIGS. 5 and 6 show the holding device 9 together with the circuit board 7 disposed in the holding device 9. FIG. 8 is a cross-sectional view of the holding device 9 into which the circuit board 7 is inserted. For better understanding, FIG. 9 also shows an enlarged view of detail I in FIG. 8.

[0102] The holding device 9 is designed to be substantially plate-shaped and ring-shaped, and includes a plurality of notches 91 for receiving the lateral legs 27 of the coil core 25. Exactly one notch 91 is provided for each lateral leg 27 such that the number of notches 91 is equal to the number of coil cores 25. The holding device 9 is inserted into the confinement can 21 (see FIG. 1) and extends axially A from the bottom of the confinement can 21 to the lower edge as shown in the illustration (FIG. 1) above the winding 61 in the axial direction A according to the illustration.

[0103] The holding device 9 is designed to be ring-shaped so that it can be disposed around the cup-shaped recess 211 of the confinement can 21, that is, the radially outer side of the cup-shaped recess 211 is surrounded by the holding device 9.

[0104] The holding device 9 has an axial edge region 92 with an outer diameter smaller than the remaining diameter of the holding device 9. According to the illustration in FIG. 6, this axial edge region 92 is the upper axial edge region. In the axial direction A, the axial edge region 92 ends at a protrusion 93 where the outer diameter of the second holding device 9 increases. The embodiment with the smaller-diameter axial edge region 92 and the protrusion 93 serves to ensure that the confinement can 21 can surround the holding device 9 radially outwardly. This can be recognized particularly in FIG. 1. The confinement can 21 has a radially outer edge 212 that surrounds the axial edge region 92 of the second holding device 9 in the assembled state. The radially outer edge 212 is designed to have a length in the axial direction A that extends up to the protrusion 93 at most.

[0105] The holding device 9 is preferably formed from plastic, particularly preferably plastic that can be produced by injection molding. The holding device 9 is thus preferably designed as an injection molded part. Plastics suitable for the production of the holding device 9 are, for example, acrylonitrile butadiene styrene (ABS), polyamide (nylon, PA), polypropylene (PP), or fiber-reinforced polypropylene.

[0106] The holding device 9 serves both as a holder for the circuit board 7 and as a holder for the magnetic field sensor 8 that can very precisely position the magnetic field sensor 8 relative to the cup-shaped recess 211 by means of that holder. For this purpose, cavities 95 bounded by an inner wall 951 and an outer wall 952 in the radial direction are provided in each holding device 9 for the respective magnetic field sensor 8, into which the magnetic field sensor 8 can be pushed, and the cavities 95 are dimensioned such that the inner wall 951 and the outer wall 952 are arranged flat against the magnetic field sensor 8. This can be recognized best in FIG. 9.

[0107] Here, it is a substantial aspect that the inner wall 951 and the outer wall 952 of the cavity 95 are arranged flat with respect to the magnetic field sensor 8. This is because it means that the position of the magnetic field sensor 8 with respect to the cup-shaped recess 211 is known with very high precision. The magnetic field sensor 8 is preferably designed in a rectangle. The cavity 95 is dimensioned such that the magnetic field sensor 8 can be completely inserted into the cavity 95 with respect to the axial direction A. Thus, the cavity 95 forms a pocket for the magnetic field sensor 8 that is at least as deep in the axial direction A as the extent of the magnetic field sensor 8 in the axial direction A. The width of this pocket in the radial direction, i.e., the distance measured in the radial direction between the inner wall 951 and the outer wall 952, is dimensioned to correspond to the extent of the magnetic field sensor 8 in the radial direction, whereby the magnetic field sensor 8 can be pushed into the cavity 95 in the axial direction, and thereby the inner wall 951 and the outer wall 952 of the cavity 95 are arranged flat with respect to the magnetic field sensor 8.

[0108] In this embodiment where the magnetic field sensor 8 is surrounded by the cavity 95 on three sides, on the one hand, the position of the magnetic field sensor 8 is known with very high precision, and on the other hand, the magnetic field sensor 8 arranged 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 the outer wall 952 slightly obliquely with respect to the axial direction such that the cavity 95 is slightly conical when viewed in the axial direction A, whereby the cavity 95 tapers upward with respect to the illustration in FIG. 9.

[0110] Furthermore, it is preferable that each magnetic field sensor 8 be arranged as close as possible to the cup-shaped recess 211. For this purpose, the inner diameter of the holding device 9 is dimensioned to be the same size as or only very slightly larger than the outer diameter DA (FIG. 11) of the cup-shaped recess 211 of the confinement can 21. Accordingly, in the assembled state, the wall portion of the holding device 9 that forms the inner wall 951 of the cavity 95 is arranged with respect to the cup-shaped recess 211 of the confinement can 21. When viewed in the radial direction, the inner wall 951 that defines the boundary of the cavity 95 is accordingly arranged between the cup-shaped recess 211 of the confinement can 21 and the magnetic field sensor 8, respectively.

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

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

[0113] In FIG. 9, an embodiment is shown in which a guide element 96 forms an outer wall 952 for the cavity 95. For better understanding, FIG. 10 further shows a perspective view of a separate guide element 96 of FIG. 9. Such separate guide elements 96 are provided for their respective cavities 95, and thus, in this embodiment, there are six such guide elements 96. The separate guide element 96 is a separate component that is simply pushed into the holding device 9 after the holding device 9 has been manufactured, i.e., it is separate from the holding device 9, thereby forming a cavity 95 for the magnetic field sensor 8. Since the guide element 96 is a separate component, it can be manufactured with very high precision, which is advantageous for the accuracy of the position of the magnetic field sensor 8. In addition, the separate guide element 96 makes it particularly easy to adapt the dimensions of the cavity 95 to the respective magnetic field sensors 8.

[0114] As can be best recognized in FIG. 9, each separate guide element 96 has an L-shaped profile. The separate guide element 96 has a bottom 961 (FIG. 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 an outer wall 952 that defines the boundary of the cavity 95. The side wall 962 includes two parallel guides 963, and when the guide element 96 is inserted into the holding device 9, the magnetic field sensor 8 is pushed between those guides 963. The two parallel guides 963 have a distance D1 from each other that corresponds to the corresponding extent of the magnetic field sensor 8, whereby the magnetic field sensor 8 can be pushed between the two guides 963 and is guided by the guides 963 in the process. The two guides 963 have a length L that is the extent of the guides 963 in the axial direction in the inserted state. The length L is dimensioned such that it is at least as large 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 already mentioned, the holding device 9 in the embodiments described herein is designed to be able to accommodate the circuit board 7 on which the magnetic field sensor 8 is disposed. For this purpose, the holding device 9 includes a ring-shaped edge 97 (FIG. 9) provided with a shoulder 98, and the shoulder 98 is disposed radially inwardly with respect to the edge 97. The shoulder 98 is designed and arranged such that the circuit board 7 can be disposed on the shoulder 98 and the circuit board 7 is disposed with respect to this shoulder 98. Optionally, the circuit board 7 can be attached to the shoulder 98, and thus to the holding device 9, by means of a plurality of screws 75. Preferably, the edge 97 is designed to project beyond the circuit board 7 with respect to the axial direction A. This has the advantage that a potting compound can be poured over the entire holding device 9 and the circuit board is completely covered by the potting compound.

[0116] FIG. 11 shows in cross-section the containment can 21 of the stator 2 of an embodiment of a magnetic levitation device, the cross-section being made in the axial direction A.

[0117] The containment can 21 having a cup-shaped recess 211 is preferably designed integrally. The containment can 21 is preferably formed from a plastic, particularly preferably a plastic that can be processed by injection molding. Thus, the containment can 21 is preferably designed as an injection molded part. Plastics suitable for the manufacture of the containment can 21 are, for example, acrylonitrile butadiene styrene (ABS), polyamide (nylon, PA), polypropylene (PP), polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane (PFA), polyvinyl chloride (PVC), polybutylene terephthalate (PBT), polyimide (PI), polyether ketone, polysuccinimide (PSI), polyphthalamide (PPA), or polyether ether ketone (PEEK).

[0118] The confinement can 21 includes a cup-shaped recess 211 into which the rotor 3 can be inserted and a radially outer edge 212 that surrounds the axial edge area 92 of the holding device 9 in the assembled state.

[0119] In the following, it will be explained how the magnetic levitation device can be assembled in a very simple manner. The assembly can be carried out, for example, as follows. The sensor substrate 7 on which the magnetic field sensors 8 are arranged and mounted is inserted into the holding device 9. For this purpose, 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. Optionally, the circuit board 7 is attached to the holding device 9 by screws 75.

[0120] Subsequently, the holding device 9 is completely filled with the first potting material 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. During the operation of the magnetic levitation device, particularly in the region of the holding device 9 in which the magnetic field sensors 8 are arranged, strong and frequent temperature fluctuations can occur. The flexible potting compound is more resistant to such fluctuations. Therefore, the flexible potting compound is preferred for filling the holding device 9.

[0121] Pass the coil core 25 through the notch 91 of the holding device 9 and the concentrated winding 61. Place the magnetic back iron 22 between the first ends 261 of the longitudinal legs 26. Insert the holding device 9, the back iron 22, and the coil core 25 with the concentrated winding 61 disposed thereon into the stator housing 101 of the housing 10 in a first mounting direction in the axial direction A (from the left according to the illustration in FIG. 2). In this step, pass the electrical connection element 76 through the stator housing 101 parallel to the longitudinal legs 26 of the coil core 25 and into the control housing 102.

[0122] When the holding device 9, the winding 61, the back iron 22, and the coil core 25 are disposed in the stator housing 101 of the housing 10, place the containment can 21 on the housing 10 and dispose the seal 201 between the containment can 21 and the housing 10 to connect to the housing 10 in a sealed state, preferably a hermetically sealed state.

[0123] Subsequently, pour a thermally conductive potting compound 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 excellent thermal conductivity in order to quickly and reliably dissipate the heat generated in the operating state into the housing, and the heat is then dissipated from the housing mainly by convection. As the second thermally conductive potting compound, for example, polyurethane, epoxy resin, acrylic resin, or polyester is suitable.

[0124] After pouring a second potting compound into the stator housing 101 of the housing 10, the control unit 40 is inserted into the control housing 102 of the housing 10 in a second mounting direction, which is opposite to the first mounting direction. Thus, according to the illustration in FIG. 2, the control unit 40 is inserted into the control housing 102 from the right side. An electrical connection element 76 is connected to the control unit 40.

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

[0126] Optionally, for example, in applications using highly corrosive, erosive or explosive fluids, a potting compound can also be poured into the control housing 102 of the housing 10. When also pouring into the control housing, this is done before the housing cover 11 is arranged on the housing 10 and firmly connected to the housing 10.

[0127] Furthermore, a centrifugal pump 100 is proposed according to the present invention, which includes a magnetic levitation device 1 and a rotor 3, and the magnetic levitation device 1 is designed according to the present invention. The magnetic levitation device 1 is designed to generate a torque acting on the rotor 3 that can drive the rotation of the rotor 3 about the axial direction A in addition to the non-contact magnetic levitation of the rotor 3.

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

[0129] The centrifugal pump 100 includes a pump unit 50 having a pump housing 51 including an inlet 52 and an outlet 53 for the fluid to be conveyed. The rotor 3 is disposed within the pump housing 51 and includes a plurality of vanes 54 for conveying the fluid. The pump unit 50 is designed such that the pump unit 50 can be inserted into the containment can 21 of the stator 2, whereby the magnetically effective core 31 of the rotor 3 is surrounded by the end face 271 of the lateral leg 27.

[0130] Since the rotor 3 is both a magnetically levitated rotor 3 and the rotor 3 of the centrifugal pump 100 by which the fluid is conveyed, it is an advantageous aspect that the rotor 3 is designed as an integral rotor. This embodiment as an integral rotor provides the advantages of a very compact and space-saving design.

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

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

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

[0134] The rotor 3 includes a plurality of vanes 54 for conveying a fluid. For example, in the embodiment described herein, a total of four vanes 54 are provided, and this number is an exemplary feature. The rotor 3 further includes a jacket 38, by which the magnetically effective core 31 of the rotor 3 is surrounded and preferably hermetically encapsulated, whereby the magnetically effective core 31 of the rotor 3 is not in contact with the fluid being conveyed. All vanes 54 are arranged on the jacket 38 and are equally spaced in the circumferential direction of the rotor 3. Each vane 54 extends radially outward and is connected to the jacket 38 in an anti-torque manner. The vanes 54 may be separate components that are later fixed to the jacket 38. Of course, it is also possible that all vanes 54 are an integral part of the jacket 38, i.e., the jacket 38 is designed as an integral part together with all vanes 54. The rotor 3 provided with the vanes 54 forms the wheel or impeller of the centrifugal pump 100, whereby one or more fluids are acted upon.

[0135] Depending on the terminology, it is preferred that the pump housing 51 of the pump unit 50, as well as the jacket 38 and the vanes 54, are formed from one or more plastics. Suitable plastics are 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, materials known under the trade name Teflon, polytetrafluoroethylene (PTFE), and perfluoroalkoxy polymer (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, for example, mixing devices for mixing fluid substances, for example, 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 contactless magnetic levitation of a rotor (3) including a disk-shaped or ring-shaped magnetically effective core (31), the magnetic levitation device having a stator (2) including a plurality of coil cores (25), each of the coil cores (25) having a longitudinal leg (26) extending from a first end (261) to a second end (262) in an axial direction (A), and a front end (263) disposed at the second end (262) of the longitudinal leg (26). and transverse legs (27) extending in a radial direction perpendicular to the axial direction (A), at least one concentrated winding (61) is provided on each of the longitudinal legs (26), the winding surrounding each of the longitudinal legs (26), and the stator (2) further has a cup-shaped recess (211) into which the rotor (3) can be inserted, the cup-shaped recess (211) being disposed at an axial end of the stator (2). a ring-shaped holding device (9) having a cavity (95) for each of the magnetic field sensors (8), the cavity being radially bounded by an inner wall (951) and an outer wall (952), the magnetic field sensors (8) being able to be pressed into the cavity (95), the cavity (95) being dimensioned so that the inner wall (951) and the outer wall (952) are positioned flat against the magnetic field sensors (8).

2. 2. The magnetic levitation device of claim 1, wherein a circuit board (7) is arranged between the winding (61) and the lateral leg (27) in the axial direction (A), all of the magnetic field sensors (8) are arranged on the circuit board, and the second holding device (9) is designed to accommodate the circuit board (7).

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

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

5. 5. The magnetic levitation device according to claim 1, wherein the holding device (9) has a separate notch (91) for each of the coil cores (25), the notch surrounding the coil core (25) and accommodating the lateral legs (27) of the coil core (25).

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

7. 3. The magnetic levitation device according to claim 1 or 2, wherein exactly six of said coil cores (25) are provided.

8. 3. A magnetic levitation device according to claim 1 or 2, comprising exactly six magnetic field sensors (8), preferably equally spaced around the circumference of the cup-shaped recess (211).

9. 4. The magnetic levitation device according to claim 2 or 3, 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. 3. The magnetic levitation device of claim 1, wherein a separate guide element (96) is provided for each cavity (95), the guide element forming the inner wall (951) and the outer wall (952) that define the boundary of the cavity (95).

11. 3. The magnetic levitation device of claim 1, wherein the stator (2) has a containment can (21) that forms an axial end of the stator (2), the containment can (21) has a cup-shaped recess (211) into which the rotor (3) can be inserted, and the containment can (21) radially surrounds the second holding device (9).

12. 3. The magnetic levitation device of claim 1, further 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 accommodate the coil core (25) having a concentrated winding (61) arranged thereon, and the control housing (102) is designed to accommodate a control unit (40) for controlling the winding (61) to generate an electromagnetic field and for supplying electrical energy to the winding (61).

13. 13. The magnetic levitation device of 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, the first mounting direction facing in a direction opposite to the second mounting direction.

14. 3. The magnetic levitation device according to claim 1 or 2, wherein the stator (2) is designed to generate a torque capable of magnetically driving the rotor (3) without contact for rotation about the axial direction (A).

15. A centrifugal pump for conveying a fluid, comprising a magnetic levitation device (1) according to claim 14 and a rotor (3) with a magnetically effective core (31), the rotor (3) being insertable into a cup-shaped recess (211) of a containment can (21), the rotor (3) being designed as the rotor (3) of the centrifugal pump.

Images