MAGNETIC STORAGE DEVICE AND POSITIONING SYSTEM

Description

[0001] The present invention relates to a magnetic storage device and a positioning system.

[0002] A magnetic bearing device according to the preamble of claim 1 is known from publication 1 "Design of Novel Permanent Magnet Biased Linear Magnetic Bearing and its Application to High-Precision Linear Motion Stage", Sang-Ho Lee et al., and publication 2 "The High Precision Linear Motion Table With a Novel Rare Earth Permanent Magnet Biased Magnetic Bearing Suspension", Dong-Chul Han et al. Further related prior art is disclosed in US 2015 / 211575 A1, CN 109 690 099 A, and US 2020 / 248747 A1.

[0003] Publication 1 describes a magnetic bearing device comprising a stator and a rotor movable relative to the stator along a direction of motion. The magnetic bearing device is essentially composed of flux guides, magnets, and coils, and is configured such that when electrical energy is applied to the coils, it can exert a magnetic force on the rotor. This force fully compensates for the rotor's weight and thus acts as a lifting force. In particular, the current-carrying coils generate a magnetic field that interacts with the magnetic field generated by the magnets. The active elements (coils) are located in the rotor, which has the disadvantage that the cables required for the electrical power supply must be attached to the rotor and moved along with it when the rotor moves relative to the stator.Alternatively, wireless power transmission would have to be provided or energy storage elements would have to be integrated into the rotor, which would significantly increase the rotor's weight. Furthermore, with this configuration, the electrically induced heat input can only be dissipated via air and possibly via cables.

[0004] Publication 2 describes an XY table, which also incorporates part of the structure of the magnetic bearing device from Publication 1. However, in this case, the active elements (coils) are part of the stator, eliminating the need to supply electrical energy to the rotor. Disadvantages of this configuration include the significantly reduced travel and the change in the force application points relative to the rotor coordinate system during the rotor's movement. In particular, the force application points are position-dependent due to the geometric dimensions, resulting in position-dependent lever arms with respect to torque. This is detrimental to the control of such a system and also leads to position-dependent power consumption along the direction of movement.

[0005] Therefore, the invention is based on the objective of improving a magnetic bearing device according to the preamble of claim 1 in such a way that a simple and independent configuration of the runner, a sufficiently large dissipation of the electrically induced heat input and a position-independent control over a longer travel distance is achieved.

[0006] To solve this problem, the present invention provides a magnetic bearing device according to claim 1.

[0007] The problem is solved by arranging the coil device exclusively in the stator and by making the extension of the rotor in the direction of motion smaller than the extension of the stator in this direction, wherein the extension of the stator corresponds to the length of the coil bodies and the coil device has coil bodies arranged one above the other in a direction perpendicular to the direction of motion and the magnets are arranged in a plane perpendicular to the direction of action of the magnetic force between the coil bodies.

[0008] Because the active element (i.e., the coil assembly or its coil former) is part of the stator, no energy needs to be transferred to the rotor. The rotor is therefore a completely passive assembly, which can be minimized in size and weight. This allows for a reduction in the forces required for acceleration and movement, or for the achievement of higher accelerations. Overall, the power input required to move the rotor along the stator can be significantly reduced. Furthermore, there is virtually no magnetization reversal in the flux guides along the direction of movement, resulting in very low hysteresis losses in the flux guides.

[0009] Due to the arrangement of the coil assembly within the stator, heat input occurs exclusively within the stator. Since a high degree of thermal coupling can be achieved between the stator, as a stationary component, and an adjacent structure, particularly a housing, the heat input can be effectively dissipated from the stator.

[0010] The smaller extension of the rotor in the direction of movement, compared to that of the stator in the same direction, results in a lever arm length that is independent of position. Consequently, the power requirement is independent of the rotor's position, creating a more linear system from a systems theory perspective. Furthermore, this allows the rotor to be moved along the stator with significantly smaller changes in the resulting torques. As a result, the magnetic bearing device according to the invention enables the rotor to be moved along the stator with no, or virtually no, change in the force and torque constants, similar to a mechanical guide.

[0011] Because the coil device has coil bodies arranged one above the other in a direction perpendicular to the direction of movement, and the magnets are arranged in a plane perpendicular to the direction of action of the magnetic force between the coil bodies, magnetic fields can be generated that act selectively with each other or selectively against each other.

[0012] Advantageous further training is the subject of sub-claims.

[0013] It can be advantageous if the rotor's extension in the direction of motion is less than 3 / 4, preferably less than 1 / 2, more preferably less than 1 / 3, and particularly preferably less than or equal to 1 / 4, of the stator's extension in that direction. The advantages described above can be further enhanced by decreasing the rotor-to-stator extension ratio. Furthermore, various installation space requirements can be met by adjusting the extension ratio.

[0014] It can be advantageous if the rotor comprises at least two flux guides arranged on opposite sides of the stator and connected by an at least partially non-magnetic element. This configuration allows the rotor to surround the stator in the most compact design possible. Preferably, the connecting element is made of a non-magnetizable material to achieve a compact design. If a compact design is not critical, it can be advantageous to use a magnetizable material for the connecting element, provided that there is a sufficiently large distance to the stator to keep the flux in the intervening air gap low, thus resulting in no or only minimal attractive forces.It is conceivable to design the flux-conducting side part of the stator, which is closer to the connecting element, in an "E-shape" and to insert another coil within it. This would make it possible to generate a lateral force with a small air gap to the connecting element, which is made of a magnetizable material.

[0015] It can also be advantageous if each coil former of the coil assembly extends in its own plane (xy), preferably with the length of the magnets and flux guides of the stator in the direction of movement corresponding to the length of the parallel sections of each coil former. Having the magnets, flux guides, and parallel sections of the coil formers of the same length creates a homogeneous area, enabling a high degree of uniformity in the rotor's movement.

[0016] It can be advantageous if the magnets in the stator are each arranged between two flux guides. This arrangement prevents demagnetization of the magnets by the magnetic field generated by the coil assembly.

[0017] It can be advantageous if each coil body has an opening and a flux guide is arranged in the opening of each coil body.

[0018] It can be advantageous if each coil former is arranged between two parallel flux guides, preferably extending in the direction of motion, and preferably at least one of these flux guides has a coupling section at which it can be coupled to another structure, preferably a housing. In this configuration, the flux guide not only conducts the magnetic flux but also serves as a structural component for connecting the stator to a housing.

[0019] It can also be advantageous for the stator to have a central flux guide with a cross-shaped cross-section, with opposing sections of the central flux guide arranged in the openings of different coil formers. This configuration allows for targeted guidance of the magnetic flux while maintaining a compact design. However, other cross-sections for the central flux guide are also conceivable, such as those with a plate-like geometry. Such a cross-sectional geometry offers the advantage of significantly reduced manufacturing costs for the flux guide.

[0020] It can be advantageous if the magnets and / or the flux guides are made in one piece or in sections.

[0021] It can be practical if the magnetic bearing device includes a magnetic guide configured to keep the runner in a plane perpendicular to the magnetic force and in a

[0022] to move in a direction perpendicular to the direction of movement. By generating a magnetic lateral force that acts in the plane perpendicular to the direction of action of the magnetic lifting force and in a direction perpendicular to the direction of movement, positioning of the runner in this direction can be made possible.

[0023] It can be advantageous for the magnetic guide to include a guide runner that is connected to the runner, preferably via a non-magnetic material. This allows for the creation of an assembly on which both the magnetic lifting force and the magnetic lateral force act.

[0024] It can be advantageous if the magnetic guide has a coil assembly with a pair of coil formers extending in a plane, wherein the stator and the rotor are arranged in a direction perpendicular to this plane above the coil formers, and the guide rotor is arranged between the rotor and the coil formers, the guide rotor having permanent magnets which are preferably arranged in a Halbach array configuration. The coil assembly of the magnetic guide has multiple coil formers.

[0025] Configurations of the permanent magnets that differ from the Halbach array arrangement are also possible for the guide runner.

[0026] Furthermore, the present invention comprises a positioning system comprising at least one magnetic bearing device according to one of the preceding embodiments, a housing, and a platform, wherein the stator is coupled to the housing and the platform is coupled to the rotor. With such a positioning system, it is possible to position the platform relative to the stator without frictional losses.

[0027] It can be advantageous for the positioning system to also include a linear motor configured to move the platform relative to the housing in the direction of movement. Highly precise positioning of the platform can be achieved by selecting the appropriate control parameters for the linear motor and the magnetic bearing device.

[0028] It can be advantageous if the positioning system includes at least one electronic component with at least one sensor, preferably in the form of a sensor board. It is conceivable that the positioning system comprises further electronic components, such as a motor driver, a motor controller, and logic digital components. It can be advantageous for two or more electronic components to be arranged on a common circuit board or printed circuit board. This measure reduces power consumption, as no power losses occur via otherwise necessary leads or cables. Furthermore, the spatial integration of the electronic component(s) allows for a very compact design of the positioning system, thus eliminating the need for an external controller. Terms and definitions

[0029] The term "coil device" in its simplest form refers to a coil former whose windings are arranged concentrically and in a common plane. It also includes a coil former whose concentric windings extend in several different planes. In this case, the windings of a coil former can be embedded in a material, such as an epoxy resin. It is conceivable to connect or couple individual coil formers of the coil device electrically in parallel or in series.

[0030] The term "non-magnetic" describes both non-magnetizable and very weakly or not permanently magnetizable materials, and specifically excludes materials with permanent magnetic or ferromagnetic properties. Non-magnetizable materials include, for example, aluminum, while "magnetizable materials" include ferro- or paramagnetic materials such as iron or alkali metals. Brief description of the characters

[0031] Fig. 1 shows a perspective view of an embodiment of the magnetic bearing device according to the invention. Fig. 2 shows a cutaway perspective view of the embodiment according to Fig. 1 . Fig. 3 shows a perspective view of a further development of the embodiment of the magnetic bearing device according to Figure 1, which includes a magnetic guide in the form of a pair of coil bodies arranged side by side and a guide rotor. Fig. 4 shows a cutaway perspective view of the embodiment according to Fig. 3 . Fig. 5 shows a sectional view of the embodiment according to Fig. 4 . Fig. 6 shows a perspective view of a positioning system according to the invention. Fig. 7 The positioning system shows according to Fig. 6 , although the platform is not shown for illustrative purposes. Fig. 8 shows a rear view of the positioning system according to Fig. 6 , although for illustrative purposes the housing and stators are not shown. Detailed description of preferred embodiments

[0032] Preferred embodiments of the present invention are described in detail below with reference to the attached figures.

[0033] Fig. 1Figure 1 shows an embodiment of the magnetic bearing device 1 according to the invention in a perspective view. The magnetic bearing device 1 comprises a stator 2 and a rotor 3.

[0034] The stator 2 includes a coil assembly 4 with two separate and electrically unconnected coil formers 4-1, arranged one above the other in the z-direction and consequently in parallel xy-planes. The length of the coil formers 4-1 extends in the x-direction. The stator 2 further comprises three flux guides 6a, 6b, 6c made of magnetizable steel and four magnets 5 (only two of which are shown in the figures), the lengths of which also extend in the x-direction. Fig. 2It can be seen that two flow guide pieces 6b, 6c, as outer flow guide pieces 6b, 6c, flank the coil formers 4-1 such that the latter are located in the y-direction between the two outer flow guide pieces 6b, 6c. The third flow guide piece 6a, as central flow guide piece 6a, is arranged in the y-direction between the outer flow guide pieces 6b, 6c and in the z-direction between the coil formers 4-1. In the present embodiment, the central flow guide piece 6a has a cross-shaped cross-section and thus projects with opposing sections into the openings of the coil formers 4-1. One of the outer flow guide pieces 6c is also provided with a coupling section that extends along the flow guide piece 6c in the x-direction and enables connection to another structure, in particular a housing.The two magnets 5 are arranged in the y-direction between an outer flux guide piece 6b, 6c and the central flux guide piece 6a, and in the z-direction between the coil formers 4-1. The height of the flux guide pieces 6a, 6b, 6c in the z-direction is chosen such that the flux guide pieces 6a, 6b, 6c are flush with the upper and lower end faces of the coil formers 4-1, respectively. This forms two essentially flat main surfaces of the stator 2. Deviations from the flush alignment of the flux guide pieces 6a, 6b, 6c with the upper and lower end faces of the coil formers 4-1 are possible.Various end faces of the coil formers 4-1 are possible, whereby for certain applications a significant projection of the flux guides 6a, 6b, 6c beyond the end faces of the coil formers 4-1 is advantageous, for example in vacuum applications, in order to guide the magnetic flux through a kind of airlock, with magnetic return taking place within the vacuum, while the coil formers 4-1 and magnets 5 are arranged outside the vacuum. If the flux guides 6a, 6b, 6c project below the end faces of the coil formers 4-1, an E-shape can be chosen for the return path. It is also conceivable that only some of the flux guides 6a, 6b, 6c terminate with the end faces of the coil formers 4-1, and the return path is correspondingly complementary in shape.

[0035] The rotor 3 comprises two preferably identical flux guides 7 arranged on opposite sides of the stator 2, and an at least partially non-magnetic element connecting the two flux guides 7 (not shown). The rotor 3 is thus designed to encompass the stator 2. The flux guides 7 may also have coupling sections that allow connection to another structure, in particular a platform. Viewed in the y-direction, the flux guides 7 project beyond the stator 2 (see in particular the figure below). Fig. 5This results in only small restoring forces in the y-direction and allows for reduced power input into the magnetic bearing device for generating movement along the y-direction. Furthermore, the flux guide pieces 7 can have a special shape, for example an "E-shape," to provide translational restoring forces in the y-direction and rotational restoring forces around the z-axis. The length of the rotor 3 in the x-direction is significantly less than the length of the stator 2 in this direction. In the present embodiment, the length of the rotor in the x-direction is 1 / 4 of the length of the stator in this direction. However, the length ratio of rotor 3 to stator 2 in the x-direction is not limited to this value but can have any value, preferably less than 3 / 4.

[0036] In general, the flux guides 6a, 6b, 6c, 7 of the stator 2 and the rotor 3, as well as the magnets 5 of the stator 2, are not limited to the shapes shown in the figures, but can have any suitable shape, in particular shapes that simplify the integration of the stator 2 and the rotor 3 into higher-level structures (e.g., housing and platform). Furthermore, the flux guides 6a, 6b, 6c, 7 and magnets 5 can be formed either as a single piece or in sections. In particular, it is conceivable to construct the flux guides 6a, 6b, 6c, and 7 in layers or as a laminate, with alternating layers of magnetizable material and layers of electrically non-conductive material. The coil formers 4-1 are preferably wire coils. However, it is also possible to use foil coils or printed coils.

[0037] By applying electrical energy to the coil formers 4-1, the magnetic bearing device 1 can be controlled. The current-carrying coil formers 4-1 generate magnetic fields in the flux guides 6a, 6b, 6c, 7, which interact with the magnetic field generated by the magnets 5. In particular, these magnetic fields can interact with each other or against each other. If the magnetic field of the upper coil former 4-1 opposes the magnetic field of the magnets 5 in the upper part of the flux guides 6a, 6b, 6c, 7, then the magnetic field of the lower coil former 4-1 can reinforce the magnetic field of the magnets 5 in the lower part of the flux guides 6a, 6b, 6c, 7 by correctly selecting the control parameters (current direction).

[0038] By appropriately selecting the control parameters, a magnetic force (lifting force) can be exerted on the rotor 3, resulting in the formation of an air gap between the upper flux guide 7 of the rotor 3 and the upper main surface of the stator 2, as well as between the lower flux guide 7 of the rotor 3 and the lower main surface of the stator 2. In particular, the size of the air gap, i.e., the distance between the main surfaces of the stator 2 and the flux guides 7 of the rotor 3 in the z-direction, is adjustable by modifying the control parameters. This magnetic force, acting as a lifting force, is thus able to compensate for the weight of the rotor 3. With simultaneous stabilization of the rotor 3 with respect to its rotational degrees of freedom about the X and Y axes, the rotor 3 floats and can be moved frictionlessly relative to the stator 2 along the x-direction.

[0039] The travel distance of the rotor 3 is essentially determined by the length of the flux guides 6a, 6b, 6c and the magnets 5 of the stator 2. Due to the length ratio of rotor 3 to stator 2 in the x-direction described above, correspondingly large travel distances can be achieved. Furthermore, it is possible to connect several stators 2 in series along the x-direction and control them appropriately in order to further increase the travel distance of the rotor 3 in a continuous system.

[0040] The Figs. 3 to 5This shows a further development of the magnetic bearing device 1 according to the embodiment described above. This further development additionally includes a magnetic guide 8 configured to move the rotor 3 in the y-direction. In particular, a magnetic force (lateral force) is generated by means of the magnetic guide 8, which moves the rotor in the y-direction. This allows the position of the rotor 3 in the y-direction to be adjusted. The magnetic guide 8 comprises a coil device with a pair of coil formers 10, which are arranged in a common xy-plane below the rotor-stator assembly, and a guide rotor 9, which is arranged in the z-direction between the pair of coil formers 10 and the rotor-stator assembly. The guide rotor 9 is connected to the rotor 3 via a connecting element made of aluminum, which is not shown in the figures. However, the connecting element can be made of any other material.If, for example, magnetic coupling is desired to increase the flux in the lower flux guide 7, it can be advantageous to make the connecting element from a magnetizable material. Increasing the flux in the lower flux guide 7 can be advantageous to create an asymmetric force characteristic or an offset in the force characteristic for the magnetic bearing device 1, thus compensating for part of the weight force. In the present embodiment, this connection is preferably formed between the facing surfaces of the guide runner 9 and the lower flux guide 7 of the runner 3. Furthermore, the guide runner 9 comprises permanent magnets arranged in a Halbach array configuration, although other arrangements of the permanent magnets relative to each other are also conceivable. Depending on the application, the guide runner 9 can be magnetically coupled to or magnetically decoupled from the runner 3.

[0041] The Figs. 6 to 8 Figure 11 shows a positioning system 11 comprising four magnetic bearing devices 1 according to the embodiment described above, four magnetic guides 8, a housing 12, a platform 13, and a linear motor 14. However, it is conceivable to use mechanical guides or air bearings instead of magnetic guides. The housing 12 is designed as a rectangular plate, with the plate having a side wall on two opposite sides. Two magnetic bearing devices 1 are arranged one behind the other along each side wall. One of the outer flux guides 6c of the stator 3 of each magnetic bearing device 1 is attached to the corresponding side wall by means of its coupling section. The stator part (coil assembly) of a linear motor 14 is arranged in the center of the plate.

[0042] Platform 13 is coupled to each runner 3 of the four magnetic bearing devices 1. How Fig. 8 As shown, the platform 13 is coupled to both the lower and upper flow guide pieces 7 of each runner 3. The coupling to the upper flow guide pieces is achieved via recesses in the platform surface. The coupling to the lower flow guide pieces 7 is achieved via two connecting webs 15 located on the underside of the platform 13. Each connecting web 15 links the platform 13 to the lower flow guide pieces 7 of two runners 3 arranged one behind the other. Furthermore, the runner section (permanent magnets) of the linear motor 14 is located in the center of the platform 13.

[0043] The positioning system 11 described above enables 6D positioning of the platform 13 without friction losses. Furthermore, highly precise positioning of the platform 13 can be achieved by selecting the appropriate control parameters.

[0044] The number of magnetic bearing units 1 in the positioning system 11 is not limited to four and can be adjusted depending on the application or installation situation. In the simplest case, it is sufficient if the positioning system 11 includes one magnetic bearing unit 1. Reference symbol list

[0045] 1 Magnetic bearing device 2 Stator 3 Rotor 4 Coil device 4-1 Coil former 5 Magnet 6, 6a, 6b, 6c Stator flux guide 7 Rotor flux guide 8 Magnetic guide 9 Guide rotor 10 Magnetic guide coil former pair 11 Positioning system 12 Housing 13 Platform 14 Linear motor 15 Connecting bridge

Claims

1. Magnetic bearing device (1) comprising a stator (2) and a moving member (3) which are formed from at least one coil device (4) with a plurality of coil bodies (4-1), magnets (5), and / or flux guide members (6a-6c, 7), where said moving member (3) is movable relative to said stator (2) along a linear direction of motion (x) and said stator (2) and said moving member (3) are configured such that a magnetic force can be exerted upon said moving member (3) when electrical energy is applied to said coil device (4) in order to form an air gap between said stator (2) and said moving member (3), wherein said coil device (4) is arranged exclusively in said stator (2) and the extension of said moving member (3) in said direction of motion (x) is smaller than the extension of said stator (2) in this direction, where the extension of said stator (2) in said direction of motion (x) corresponds to the length of the coil bodies (4-1), wherein said coil device (4) comprises coil bodies (4-1) arranged one above the other in a direction orthogonal to said direction of motion (x), characterized in that said stator comprises said magnets (5), wherein said magnets (5) are arranged in a plane (xy) orthogonal to the direction of action of the magnetic force between the coil bodies (4-1).

2. Magnetic bearing device according to claim 1, characterized in that the extension of said moving member (3) in said direction of motion (x) is smaller than 3 / 4, preferably smaller than 1 / 2, preferably smaller than 1 / 3, particularly preferably smaller than or equal to 1 / 4, of the extension of said stator (2) in this direction.

3. Magnetic bearing device according to claim 1 or 2, characterized in that said moving member (3) comprises at least two flux guide members (7) which are arranged on oppositely disposed sides of said stator (2) and are connected to one another by an element that is non-magnetic at least in part.

4. Magnetic bearing device according to one of the preceding claims, characterized in that each coil body (4-1) extends in its own plane (xy), where the length of said magnets (5) and flux guide members (6) of said stator in said direction of motion (x) preferably corresponds to the length of the sections of each coil body (4-1) extending in parallel.

5. Magnetic bearing device according to one of the preceding claims, characterized in that said magnets (5) in said stator (2) are each arranged between two flux guide members (6a-6c).

6. Magnetic bearing device according to one of the preceding claims, characterized in that each coil body (4-1) comprises an opening and a flux guide member (6a) is arranged in said opening of each coil body (4-1).

7. Magnetic bearing device according to one of the preceding claims, characterized in that each coil body (4-1) is arranged between two flux guide members (6b, 6c) that extend in parallel and that preferably extend in said direction of motion (x), and preferably at least one of said flux guide members (6c) comprises a coupling section at which it can be coupled to a further structure, preferably to a casing (12).

8. Magnetic bearing device according to one of the preceding claims, characterized in that said stator (2) comprises a central flux guide member (6a) with a cross-shaped cross section in a plane perpendicular to said direction of motion (x) and oppositely disposed sections of said central flux guide member (6a) are arranged in the openings of different coil bodies (4-1).

9. Magnetic bearing device according to one of the preceding claims, characterized in that said magnets (5) and / or said flux guide members (6a-6c, 7) are formed integrally or in pieces.

10. Magnetic bearing device according to one of the preceding claims, characterized in that said magnetic bearing device (1) comprises a magnetic guide (8) which is configured to move said moving member (3) in a plane (xy) perpendicular to the magnetic force and in a direction (y) perpendicular to said direction of motion (x).

11. Magnetic bearing device according to claim 10, characterized in that said magnetic guide (8) comprises a guide moving member (9) which is connected to said moving member (3), preferably by way of non-magnetic material.

12. Magnetic bearing device according to claim 11, characterized in that said magnetic guide (8) comprises a coil device with a pair of coil bodies (10) which extends in a plane (xy), where said stator (2) and said moving member (3) are arranged in a direction (z) perpendicular to this plane (xy) above said pair of coil bodies (10) and said guide moving member (9) is arranged between said moving member (3) and said pair of coil bodies (10), where said guide moving member (9) comprises permanent magnets which are preferably arranged in the configuration of a Halbach array.

13. Positioning system (11), comprising at least a magnetic bearing device (1) according to one of the claims 1 to 12, a casing (12), and a platform (13), where said stator (2) is coupled to said casing (12) and said platform (13) is coupled to said moving member (3).

14. Positioning system according to claim 13, furthermore comprising a linear motor (14) which is configured to move said platform (13) relative to said casing (12) in said direction of motion (x).