Centrifuge with a rotor for receiving a product for centrifuging

0001The invention relates to a centrifuge having an intended for receiving centrifugation material Rotor assembly comprising at least a bearing and to a drive device by means of a rotor shaft rotatably mounted, wherein at least a portion of the rotor assembly magnetic forces act.

0002The rotor arrangement is the practice of a rotor head, which the centrifuge product receives, and a rotor part in the formation of a bearing, for example, as wave- or hollow shaft-like member and is formed adjacent to a superconducting magnet stator is arranged.

0003From DT 23 14 436 A1 a storage and damping device is to stabilize Rotor motion rapidly revolving centrifuge known that without a mechanical connection requiring between rotor and ambient, the rotor at deviations from the desired Rotational axis back into this. In this static feedback forces between Rotor and around by a magnet system and at least one damping device generated, the required attenuation not only on magnetic forces but partially or completely via mechanical hydraulic or hydropneumatic forces on the Rotor occurs.

0004As problematic it proves that the damping devices not only via magnetic forces but also have mechanical and hydraulic or hydropneumatic forces the rotor can be coupled so that a relatively high technical effort is to be expected.

0005Furthermore, from the US 51 96 748 a laminate structure for a superconducting bearing known mated with said at least two magnets with opposite polarity on an axis are achieved with a high stiffness due to a high Flussdichtegradienten becomes. The structure is housed within a hollow cylinder made of superconducting material.

0006Furthermore, from DE 42 32 869 A1 a superconducting bearing unit and method known its operation, the bearing unit has a fixed to a rotating shaft of the permanent magnet and having secured a superconducting body at its periphery of a housing is surrounding the permanent magnet. The superconducting body is designed such that it at upward moving rotary shaft can be cooled until he superconducting a reached state, so that the rotary shaft during operation in a state of equilibrium between their weight and the accompanying parts and due to the pinning Effect occurring force is held, the superconductor by the permanent magnet and the Body is caused.

0007Proved to be problematic, the relatively complicated commissioning, the Rotating shaft must be raised first, that the top of the permanent magnet with the underside of the superconductor body is provided for in contact. subsequently is supplied, so that the body becomes superconductive a coolant. This is therefore a relatively costly commissioning of the described arrangement.

0008The object of the invention is to provide a centrifuge, in which the rotor during the Centrifuging magnetically spaced-contact in one or two superconducting magnetic bearings and smoothly rotates. Further to the high in an active control technology Requirements through the use of passive superconducting magnetic bearings minimized will.

0009In addition to at speeds up to 180,000 U / min high bearing stiffness, good Damping characteristics, a low-vibration, low drive power and a favorable Balance tolerances are achieved. The attenuation should be independent of frequency.

0010The object is achieved in that the rotor assembly at least one permanent magnet configuration comprises that in a predetermined distance to at least one passive superconducting magnet stator disposed adjacent, wherein the permanent magnet configuration and the magnet stator forming a magnetic bearing at least.

0011Especially advantageous proves that active on a relatively complex control storage can be dispensed with; Moreover, the storage can be a relatively robust operation for lab and production.

0012Advantageous embodiments of the centrifuge are indicated in claims 2 to 25th

0013In a preferred embodiment of the invention emerge from the permanent configuration exiting Field lines at least approximately perpendicular to at least one adjacent surface a magnetic stator a.

0014In an advantageous embodiment of the invention the rotor axis includes with respect to a horizontal plane an angle in the range of 0 to 90 °.

0015In a preferred embodiment of the invention, the rotor assembly includes at least one annular or cylindrical permanent magnet configuration, which seen in the radial direction is disposed adjacent to at least a passive, superconducting magnet stator.

0016In a first advantageous embodiment of the invention, the magnet stator surrounding at least partly the permanent magnet configuration of the rotor assembly.

0017In a second advantageous embodiment, surrounds the permanent magnet configuring the Rotor assembly the magnet stator.

0018The rotor assembly preferably comprises at least one permanent magnet configuration, seen in the axial direction to at least one passive superconducting magnet stator is adjacent; it is in an advantageous embodiment the permanent magnet configuration mounted on a rotor axle extending along the undulating part or as part of formed rotor assembly along the rotor axis, wherein at least a plurality of magnetic bearings a stator the wavy part at least partially surrounds.

0019In a further advantageous embodiment of the centrifuge is the permanent magnet configuration mounted in a hollow shaft-shaped part of the rotor assembly or as hollow wavy Part of the rotor assembly is formed, said hollow wavy with multiple magnetic bearings Part surrounding at least a stator.

0020In addition, a combination is possible, wherein the rotor arrangement comprises at least one has permanent configuration, viewed in the radial direction to a magnet stator is disposed adjacent and has at least one permanent configuration in the axial is at least adjacent seen toward a magnet stator.

0021In a preferred embodiment, the stator is of the centrifuge with a connected Cooling unit provided; Here, the stator is viewed from the drive shaft at least in Part designed as a hollow cylinder. Preferably, the stator comprises a monolithic hollow cylinder from schmelztexturiertem YBaCuO superconductor material, where this material below a temperature of 92 K or -181 ° C becomes superconductive. The stator has also polycrystalline melt textured Much domain material for the production of damping properties the magnetic bearing on.

0022In an advantageous embodiment, the stator has damping rings of copper, aluminum or their base alloys; It is possible, the cushioning rings between the superconductors arranging a stator or engage in the superconductor.

0023The stator is preferably directly integrated in the centrifuge housing chiller for cooling the superconductor connected below its critical transition temperature. It is however, also possible to the required superconducting temperature by evaporation of a Liquid with a low boiling point - for example by evaporation of liquid nitrogen to generate - at -196 ° C.

0024In an advantageous embodiment the superconducting stator is viewed from the rotor axis from formed at least in part as a hollow cylinder or ring, said at least one Stator at least one segment or sector-opening.

0025The permanent magnet configuration is preferably configured annular or cylindrical and coaxially to the rotor axis.

0026Advantageously, the permanent magnet configuration is as a ring-shaped or cylindrical Permanent magnet or a group of coaxial rings or hollow cylinders formed, the directly or with a different material than liner radially into one another and / or axially adjacent are joined.

0027In a further advantageous embodiment of the centrifuge is the permanent magnet configuration composed of axially magnetized rings which are stacked in the axial direction, wherein like poles lie on one another and generate a high local flux density in the radial direction.

0028In addition, there is provided in another embodiment of the centrifuge that the permanent configuration comprises at least two annular permanent magnets concentrically in a plane are arranged, wherein the inner circumference of an outer ring the outer periphery an inner ring touches, this can nested permanent magnet rings seen in the radial direction an equal or alternating axial magnetization exhibit.

0029In one advantageous embodiment, the permanent configuration is as a part of a rotor cup educated.

0030The permanent magnet configuration can also cylindrical of only a single annular or Permanent magnets are made.

0031In a further preferred embodiment, the stator has at least one cylindrical Aluminum or copper-finger with attached hollow cylinder of superconductor material on, whereby the drive shaft with their internal permanent magnet magnet magnetic is stably supported.

0032In a first preferred embodiment of the centrifuge rotor, a rotor housing on which is arranged at an upper end of a drive shaft having a vertical rotation axis is, wherein the drive shaft at least one pair of axially disposed annular or cylindrical shaped Permanent magnets contains. The permanent magnets are preferably arranged along the rotation axis spaced from each other, which seen in the radial direction of at least a passive superconducting magnetic bearings are surrounded as a stator.

0033In a preferred embodiment, the drive shaft for the rotor of a hollow shaft is made of a Material, preferably a material of high tensile strength such as alloys formed on the basis of aluminum, titanium, steel, or carbon fiber, with a ratio of tensile strength to density in the range of 10⁶ Pa cm³/ G to 3 x 10⁹ Pa cm³/ G is provided.

0034The drive shaft is preferably provided in this embodiment with permanent magnets, which produce a radial flux distribution and layered axially either in groups with River collectors are arranged or have radially magnetized rings.

0035In a preferred embodiment, the permanent magnet configuration also serves as a Bearing component and the drive of the rotor by an outer stator.

0036However, it is also possible for a non-contact drive device on the basis of an induction machine use.

0037In a further advantageous embodiment, the stator has Kryomagnetlager in which Copper damping rings between superconducting cylinders the rotating permanent magnet face, said about speed-dependent eddy currents, an additional bearing isolator both through the copper rings and the HTS neighboring areas due to heating is produced. The width of the gap between the annular permanent magnet of the rotor drive shaft and the stator is in the range of 1 to 5 mm.

0038The drive shaft for the rotor has at its lower end, a mechanical emergency bearing which with too little force to the magnetic effect a trouble-free start-up or braking allows the drive shaft and the rotor.

0039In a further preferred embodiment of the invention the rotor housing is at a disposed upper end of a drive shaft with a vertical rotor axis, wherein the drive shaft at least two annular or cylindrical permanent magnets, the axial seen in the direction of distance also axially arranged passive superconducting magnet are disposed; here is in contrast to the first preferred embodiment, the magnetic effect achieved no longer radially but by axially acting forces.

0040The passive superconducting magnets in a practical embodiment partly in the form of a ring or cylinder, a - possibly lockable - gap in each of the superconducting magnet is provided, through which the drive shaft together with is the permanent magnet inserted. The distance between the permanent magnets corresponding to each other substantially corresponds to the spacing of the superconducting magnet, the axial minimum distance between the permanent magnet and superconducting magnet in the range of 1 to 5 mm lies.

0041Especially advantageous has proven to be the upper bearing by extending the distance to make soft between permanent magnet and superconducting magnet, so that even a large residual unbalance of the rotor (compared to the prior art) unproblematic is.

0042In a third preferred embodiment of the invention the rotor at its warehouse for or drive end facing a hollow cylinder on which at least one of its inside includes annular or cylindrical permanent magnets, the at least one superconducting Magnet stator surrounds disposed along the rotor axis. The superconducting Magnet is connected with a cold finger, the one in a preferred embodiment on is cooling unit connected. The hollow cylinder is on its outer side with a metallic provided rotor structure of an induction motor as a prime mover.

0043In a preferred embodiment of the invention according to FIG 6, the cold finger a along the rotor axis upwardly extending bolt 41 of a material of high linear Thermal expansion - to the relief camps - preferably made of aluminum and steel; by the the superconductor outgoing cooling the bolt retracts from the relief camps once the superconductor has fixed the rotor magnetic.

0044In a preferred fourth embodiment of the invention, the rotor in the lower housing part annular permanent magnets, which on its upper side or underside with each homopolar permanent magnet disposed adjacent. The annular permanent magnets thus form a structural unit with the rotor. Below the rotor is axially symmetric to the annular permanent magnet, a likewise largely axial-symmetric arranged superconducting magnet stator, which on its upper side a having a flat surface which is directed towards the rotor base. The concentric and coplanar arranged the annular permanent magnets are in an axial direction, ie parallel to the rotor axis magnetized, wherein the field lines nearly perpendicular to the underlying magnet stator enter. Due to the effect of the superconducting magnet stator, the rotor with The aid of the annular permanent magnets at a distance above the magnetic-floating stator maintained, so that a substantially smooth mounting is possible.

0045The drive is in this case also without contact, for example, by design of the Rotor housing as the rotor of an induction machine.

0046In a further preferred embodiment of the invention, the rotor housing at its Bottom at least two concentric and coaxial annular permanent magnets on which are magnetized in each case opposite poles axially on its upper side; this means, that the magnetization seen in the radial direction in each case on the upper edges or Lower edges of the permanent magnet configuration changes. Again hovers as a permanent magnet configuration formed underside of the rotor above a superconductor cooled Magnetic stator having a planar surface and, preferably, disk-shaped is trained.

0047For low-rise centrifuges as desktop devices, it has proven to be expedient, an embodiment with high bearing capacity and tilting stiffness of the rotor, which otherwise only with a is to achieve double-spaced bearings to use. It consists of superconducting Stator of a flat ring YBCO from 100 to 400 mm in diameter and one or more flat concentrically arranged inside or outside the current permanent magnet rings, which support the rotor.

0048In the following the subject matter of the invention based on the Figures Figure 1 is explained in more detail to the 7th

0049Figure 1 schematically shows a rotor of a vertically arranged at one end Drive shaft is mounted, the spaced apart with the aid of permanent magnets in two mutually Magnetic bearings is performed;

0050Figure 2 shows a cross section through the drive shaft in its lower bearing, also a Part of the superconductive magnetic bearing is recognizable.

0051Figures 3a, 3b show different configurations of the permanent magnets on the Drive shaft with in the axial direction and without flux collector in different Intervals are arranged.

0052Figure 4 shows schematically an additional centrifuge bearings with axial and radial relief camps for unbalanced rotors.

0053Figure 5 illustrates a centrifuge bearings with removable side rotor is, in the axial Direction seen alternately arranged permanent magnets and superconducting magnets are.

00546 shows a centrifuge having outer permanent magnets a superconducting magnet surround.

0055Figure 7 shows an arrangement with an annular located in the region of the bottom of the rotor Arrangement of concentric and coplanar permanent magnets arranged with the axial magnetization, which fall together with an underlying superconducting Magnet stator form a frictionless magnetic bearings.

0056Figure 8 shows a similar arrangement as shown in FIG. 7 In contrast, However adjacent ring upper edges or ring-lower edges each formed with opposite polarity.

0057Figure 9 shows schematically a device-related configuration for magnet assembly of FIG. 8

0058According to Figure 1, the rotor 1 is fixed to the upper end of a vertically extending drive shaft 2, wherein the drive shaft 2 in two axially spaced apart bearings 3 and 4 are rotatably is arranged. Between the bearings 3 and 4, a driving device 5 is provided.

0059Each of the two magnetic bearings 3, 4 consists of the arranged on the drive shaft 2 ring- or cylindrical permanent magnets 6, 7, 8, 9 of the bearing 3, as well as 11, 12, 13, 14 of Bearing 4, wherein the permanent magnets in each of the two bearings 3, 4 at a predetermined distance are surrounded by at least one passive superconducting stator.

0060Between the permanent magnets 6 and 7, 7 and 8, 8 and 9 and 11 to 12, 12 and 13, 13 and 14 is respectively a high permeability plate 16 for guiding the magnetic flux installed such that the supplied flow through the gap 17 between stator 19 and rotor 1 perpendicularly enters the wall of the superconductor. The ring-shaped permanent magnet 6 to 9 and 11 to 14 are made of SmCo or NdFeB and produce in a stable superconductor Rotor position relative to the displacement in the axial or radial direction. caused contrast the anchored in the superconducting stator 19 during rotation of radial magnetic flux about the longitudinal axis 21 virtually no resistance. The permanent magnets 6 to 9 and 11 to 14 are due of occurring at high speeds dynamic forces with high-strength carbon fiber and Prepregharzen reinforced.

0061Advantageously, the YBCO hollow cylinder texture is layered magnetic configurations the permanent magnets on the drive shaft 2 in the manner in which maximum force formation introduced, wherein a combination of the same and / or opposite poles arranged magnetic rings the absolute values, as well as the gradient of the magnetic flux in the radial direction increase.

0062Based on Figure 2 is cross-sectional to the drive axis along a through line AA (Figure 1) indicated Level of development of magnetic bearings 4 recognizable. The centrifuge has a bearing Stator 20 includes a superconductor which purpose good thermal insulation by means in a Vacuum up to the outside around the evacuated vessel 25 is; to support the the rotor facing hollow-cylindrical inner wall 23 of the stator opposite the superconductor supported by spacers 24 having low thermal conductivity. Furthermore, in the housing 25 of the stator 20 provided charcoal areas 26 on a copper base Housing 25 and are disposed. Through the use of activated carbon is the insulation vacuum produced during cooling by a cryopump effect. Within the stator 20 is the drive shaft 2 seen, one of the permanent magnets - for example magnet 13 - in Cross section is shown. The drive shaft is constructed as a hollow shaft and runs in the superconducting Rings or cylinders of the stator 20th

0063According to Figure 3a, the permanent magnets 6 to 9 or magnetic bearings 3, 4 layered without distance mutually adjacent, said in the lead of the field lines a relatively weak anchoring in practical values ​​of the air gap of 52 mm in the superconductor of the stator 19 results. Only in the vicinity of the magnet stator superconductor of about 20.5 mm results in the formation high forces. Only through a layered arrangement of Permanent magnets 6 to 9 with intervening spacers 24 as a high-permeability Slices of each 1 to 2 mm thickness for guiding the magnetic flux is shown in FIG 3b the flow or are the magnetic field lines on the gap between the stator 19 and and the permanent magnet of the drive shaft 2 perpendicular introduced into the Supraleiterwandung. Because by increasing and guiding the magnetic flux on the side of the permanent magnets and the radial orientation of current-carrying crystallographic AB planes of the superconductor a highly stable magnetic interaction is created, can by reducing the Air gap to 1 to 2 mm by precision machining of the stator 19 and the bearing stiffness so that the positional accuracy of the rotor can be increased at all speeds on.

0064In figure 3a and the subsequent 3b respectively, an arrow C, the radial, crystallographic preferential C-direction (texture in the stator) in such a way that the current-carrying crystallographic AB planes in the cylinder wall are so particularly high shielding or magnetic forces are achieved.

0065Thus, the highly permeable discs 16 between the annular permanent magnets fitted with a thickness in the range of 1 to 2 mm for guiding the magnetic flux in such a way that the magnetic flux across the gap between stator and rotor perpendicular to the Statorleiterwandung enters. According to Figure 3b occurs due to the use of highly permeable discs 16 between the permanent magnets 6, 7, 8, 9 or 11 to 14, the magnetic flux substantially perpendicular to the inner wall 23 of the stator 19 and 20, respectively, so that a radial alignment of the permanent magnets of the drive shaft 2 of the rotor together with a highly stable magnetic interaction occurs between being by reducing the air gap the permanent magnet of the drive shaft 2 (rotor 1) and stator 19 or 20 to 1 to 2 mm by precision machining of the stator storability and thus the position accuracy the rotor can be increased at all speeds on.

0066Figure 4 schematically shows a longitudinal section through the rotor 1 and drive shaft 2, whereby the lower end 29 of the drive shaft 2 is in a bearing 30 with runflat tires. A Such an arrangement is particularly useful for an unbalanced rotor due to uneven loading during the starting process of interest. The emergency bearing 30 occurs only in the Initial phase of the centrifugation process in action, while the drive shaft 2 during slightly normal rotor run in centrifugation distinguishes them from emergency bearings 30, so that a contact-free guidance of the drive shaft 2 is possible.

0067According to Figure 5 is the rotor 1 at the top of a along a vertical axis 10 extending Drive shaft 2 is mounted, wherein provided along the drive shaft two magnetic bearings 3 ', 4' are each one integral with the drive shaft 2. Permanent magnets 6 ', 11 'exhibit. The drive shaft 2 is perpendicular to its rotation axis 10 in a housing 25 ' be introduced, which are each provided with a superconducting magnet stator along the axis 10 , wherein the two magnetic stators 19 ', 20' each have a sector-shaped opening or , 32 having slit 31 for the lateral introduction of the drive shaft second The superconducting magnet stators 19 ', 20' by a similar cooling device as already based Figure 2 described is cooled. However, it is also possible here for cooling the heat of evaporation a refrigerant with a low boiling point such as nitrogen to use. The distances of the permanent magnets 6 ', 11' corresponding to the spacing of the superconducting Magnetic stators 19 ', 20', wherein after introduction of the drive shaft 2, the housing 25 'by Closing a second housing part is not shown here is locked in place so that the drive shaft 2 continues even when ineffective magnetic storage in a low-friction guide. To improve the emergency running is still at the lower end of the drive shaft 2 a bearing is provided, as for example known from the description of FIG 4 is.

0068In Figure 6, a rotor is shown with a so-called external rotor, wherein the rotor 1 'at its the lower end is provided with a hollow cylinder 34 which at least on its inner side having an annular or cylindrical permanent magnet 35; the hollow cylinder - trained permanent magnet 35 surrounds a along the rotor axis 10 arranged superconducting Magnet stator 36, which is connected mechanically at its upper end 37 in a Emergency bearing 38 of the rotor 1 'protrudes. In this case, a cold finger along a rotor axis upwardly extending pin 41 high of a material linear thermal expansion - Preferably made of aluminum and steel - on the emergency bearings; through the superconductor Outgoing cooling pulls the pin 41 from the relief camps back once the Superconductor rotor has a magnetic coupling. On the outer periphery of the hollow cylinder 34 a rotor structure for the contactless drive according to the principle of the induction machine is provided, wherein the stator of the induction machine is denoted by numeral 40th The actual cooling device 28 is not shown for a better overview, it corresponds However, essentially the basis described in Figure 2 device.

0069According to Figure 7, the stator of the centrifuge a disc-shaped superconducting magnet stator 51, which is connected to a cooling device within the centrifuge housing. Above the superconducting magnet stator 51 is a permanent magnet configuration from three nested annular permanent magnets 52, 53, 54 shown, which to one another are arranged coaxially and co-planar with their magnetization axially to the rotor axis runs. The upper edges of the respective permanent magnets are the same pole magnetized, so that for example at the top edge of the north pole and always at the bottom always prevails the south pole. The permanent magnet configuration 55 is an integral Part of the bottom of the only schematically indicated rotor housing. As can Figure 7 is seen, contact the field lines in the same direction direction from the permanent magnet configuration in the direction of the magnetic stator from which the disk-shaped surface 58 is cut nearly perpendicularly by the field lines.

00708 shows a similar embodiment as shown in Figure 7, but here the axially magnetized annular permanent magnets 62, 63, 64 with their top edges respectively are polarized opposite poles, so that, for example, permanent magnet 62 has a north pole, the adjacent thereto permanent magnet 63 a south pole and the adjacent turn this Permanent magnet 64 has a north pole has at its upper edge. The thus opposite of the permanent configuration 65 outgoing field line intersect the surfaces 58 of the Magnet stator 51 also almost in a vertical angle. Again, the rotor housing only schematically indicated, wherein the concentric and coplanar arranged arranged annular permanent magnets in the bottom of the rotor housing are.

0071However, it is also possible in the embodiments according to FIG 7 and 8, a permanent-magnet configuration to form the severable or detachable arranged relative to the rotor housing is.

0072Figure 9 schematically shows in longitudinal section a rotor assembly having a magnetic bearing configuration according to Figure 8, after which the annular permanent magnet configuration 65 with is the bottom of the rotor housing 56. Beneath the permanent magnet configuration is disposed the magnet stator 51st