MIXING APPARATUS AND SINGLE-USE APPARATUS FOR SAID MIXING APPARATUS

Abstract

A mixing apparatus for mixing or stirring substances includes a mixing tank for receiving the substances, a rotor arranged in the mixing tank with which a vane for mixing or stirring the substances can be driven to rotate about an axial direction, and a stator arranged outside the mixing tank and with which the rotor can be driven contactlessly magnetically to rotate about the axial direction in the operating state and is supported magnetically with respect to the stator. A bar extends in the axial direction and is rotationally fixed to the rotor, and a limiting element fixed with respect to the mixing tank cooperates with the bar, with the limiting element being configured such that the bar rotates with respect to the limiting element and with a tilt of the rotor being limited by a physical contact between the bar and the limiting element.

Claims

1. A mixing apparatus for mixing or stirring substances, comprising: a mixing tank for receiving the substances to be mixed or to be stirred; a rotor arranged in the mixing tank, and including at least one vane configured to mix and stir the substances, the vane configured to be can be driven to rotate about an axial direction; a stator arranged outside the mixing tank, and configured to contactlessly magnetically drive the rotor to rotate about the axial direction in the operating state, and to magnetically support the rotor with respect to the stator; a bar extending in the axial direction and rotationally fixed to the rotor; and a mechanical limiting element fixed with respect to the mixing tank and being configured to cooperate with the bar, the limiting element being configured and arranged such that the bar is capable of rotating with respect to the limiting element and a tilt of the rotor being at least limited by a physical contact between the bar and the limiting element.

2. The mixing apparatus in accordance with claim 1, wherein the stator is a bearing and drive stator configured to contactlessly magnetically drive the rotor in the operating state and contactlessly magnetically support the rotor at least radially with respect to the stator.

3. The mixing apparatus in accordance with claim 2, wherein the rotor is passively magnetically stabilized with respect to the axial direction.

4. The mixing apparatus in accordance with claim 1, wherein the limiting element is a tilt limitation such that the bar rotates free of contact with respect to the tilt limitation with a non-tilted rotor in the operating state and such that a tilt of the rotor is limited by a physical contact between the bar and the tilt limitation.

5. The mixing apparatus in accordance with claim 1, wherein the limiting element is a mechanical bearing for the bar.

6. The mixing apparatus in accordance with claim 5, wherein the mechanical bearing is a rolling bearing, a slide bearing, a fluid-lubricated bearing or a hydrodynamic bearing.

7. The mixing apparatus in accordance with claim 5, wherein the mechanical bearing is a pendulum bearing configured to take up tilts of the bar.

8. The mixing apparatus in accordance with claim 1, wherein the limiting element is arranged inwardly one of two axial limiting surfaces of the mixing tank.

9. The mixing apparatus in accordance with claim 1, wherein the bar is secured against a separation from the limiting element.

10. The mixing apparatus in accordance with claim 1, wherein the bar extends through the limiting element in the axial direction.

11. The mixing apparatus in accordance with claim 1, in wherein the bar has an end remote from the rotor and a terminating element configured to be received by the limiting element at the end remote from the rotor.

12. The mixing apparatus in accordance with claim 8, wherein the terminating element is capable of being introduced into the limiting element via a snap-in connection.

13. The mixing apparatus in accordance with claim 1, wherein the at least one vane includes a plurality of vanes provided at the bar.

14. The mixing apparatus in accordance with claim 1 further comprising a single-use apparatus configured for single use; and a reusable apparatus configured for multiple use, the single-use apparatus comprising the mixing tank, the rotor, the at least one vane, the bar, and the limiting element, the mixing tank being a plastic flexible mixing tank; and the reusable apparatus comprising the stator and a support tank configured to receive the mixing tank.

15. A single-use apparatus for a mixing apparatus, the mixing apparatus including a reusable apparatus configured for multiple use, and including a stator and a support tank, the single-use apparatus comprising: a plastic flexible mixing tank configured to receive substances to be mixed or stirred; a rotor arranged in the mixing tank and including at least one vane configured to mix and stir the substances, the vane configured to be driven to rotate about an axial direction; a bar extending in the axial direction and being rotationally fixedly connected to the rotor in the operating state; a limiting element fixed with respect to the mixing tank and configured to cooperate with the bar, the limiting element being configured and arranged such that the bar is capable of rotating with respect to the limiting element in the operating state and a tilt of the rotor is at least limited by physical contact between the bar and the limiting element, the single-use apparatus being configured for single use and configured to cooperate with the reusable apparatus by being insertable into the support tank of the reusable apparatus, and the rotor being drivable about the axial direction by the stator of the reusable apparatus contactlessly through a magnetic rotationally field and being magnetically supportable with respect to the stator.

16. The mixing apparatus in accordance with claim 2, wherein the rotor is passively magnetically stabilized against tilting with respect to the axial direction.

17. The mixing apparatus in accordance with claim 1, wherein the limiting element is a mechanical radial bearing for the bar.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The invention will be explained in more detail hereinafter with reference to the drawings.

[0043] FIG. 1 is a sectional representation of a first embodiment of a mixing apparatus in accordance with the invention;

[0044] FIG. 2 is an embodiment of the limiting element as a roller element bearing;

[0045] FIG. 3 is an embodiment of the limiting element as a slide bearing;

[0046] FIG. 4 is an embodiment of the limiting element as a pendulum bearing;

[0047] FIG. 5 is an embodiment of the limiting element as a pendulum slide bearing;

[0048] FIG. 6 is a section through the limiting element of FIG. 5 along the line VI-VI in FIG. 5;

[0049] FIG. 7 is a sectional representation of a second embodiment of a mixing apparatus in accordance with the invention;

[0050] FIG. 8 is a sectional representation of a third embodiment of a mixing apparatus in accordance with the invention;

[0051] FIG. 9 is a plan view of the limiting element of the third embodiment from the axial direction;

[0052] FIG. 10 is a sectional representation of a fourth embodiment of a mixing apparatus in accordance with the invention; and

[0053] FIGS. 11-14 are different variants for the embodiment of the limiting element, each in a perspective representation.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0054] FIG. 1 shows in a longitudinal sectional representation a first embodiment of a mixing apparatus in accordance with the invention which is designated as a whole by the reference numeral 1. Such mixing apparatus 1 can in particular be used in the pharmaceutical industry and in the biotechnological industry. The mixing apparatus in accordance with the invention is also specifically suitable for such applications in which a very high degree of purity or sterility of those components is key which come into contact with the substances to be mixed. The mixing apparatus 1 in accordance with the invention can also be designed as a bioreactor or as a fermentor. It is understood, however, that the invention is not restricted to those embodiments, but rather relates very generally to mixing apparatus by which media or substances can be mixed or stirred. These substances can in particular be fluids or solids, preferably powders. The mixing apparatus 1 in accordance with the invention is suitable for mixing or stirring liquids among one another and/or for mixing of at least one liquid with a powder or other solid and/or for mixing gases with liquids and/or solids.

[0055] In the first embodiment shown in FIG. 1, the mixing apparatus 1 comprises a mixing tank 2 for receiving the substances to be mixed or to be stirred that is stable in shape and that is preferably manufactured from a plastic. Examples for suitable plastics will be named further below. The mixing tank 2 can have a plurality of inlets and outlets for liquid, gaseous or solid substances or for the reception of probes or measuring sensors that are not shown in FIG. 1 for reasons of better clarity.

[0056] The mixing tank 2 has two axial limiting surfaces, namely a base 22 (at the bottom in the representation in FIG. 1) and a top 23 (at the top in the representation in FIG. 1).

[0057] A disk-shaped or ring-shaped rotor 3 is arranged in the mixing tank 2, at the base 22 thereof, and a plurality of vanes 6 can be driven by it to rotate about an axial direction A and mix or stir the substances in the mixing tank 2. A stator 4 having a plurality of coil cores 41 that carry the coils or windings 42 is provided outside the mixing tank and the rotor 3 can be contactlessly magnetically driven thereby in the operating state. The stator 4 is preferably designed as a bearing and drive stator by which the rotor 3 can be contactlessly magnetically driven in the operating state and can be contactlessly magnetically supported with respect to the stator 4. The stator 4 and the rotor 3 thus form an electromagnetic rotary drive that is preferably designed in accordance with the principle of a bearingless motor.

[0058] In a bearingless motor, the rotor 3 is contactlessly magnetically drivable and is contactlessly magnetically supportable with respect to the stator 4. For this purpose, the stator 4 is designed as a bearing and drive stator by which the rotor 3 can be driven contactlessly magnetically about a desired axis of rotation in the operating state—that is it can be set into rotation—and can be supported contactlessly magnetically with respect to the stator 4. That axis is called the desired axis of rotation about which the rotor 3 rotates in the operating state when the rotor 3 is in a centered and non-tilted position with respect to the stator 4. This desired axis of rotation defines the axial direction A, i.e. the axial direction A is the direction of the desired axis of rotation. The desired axis of rotation fixing the axial direction A typically coincides with the central axis of the stator 4. A direction perpendicular to the axial direction is called a radial direction.

[0059] The bearingless motor has in the meantime become sufficiently well-known to the skilled person so that a detailed description of its function is no longer necessary. The term bearingless motor means that the rotor 3 is supported completely magnetically, with no separate magnetic bearings being provided. The stator 4 is configured for this purpose as a bearing and drive stator; it is therefore both the stator of the electric drive and the stator of the magnetic support. The stator 4 in this respect comprises the windings 42 by which a magnetic rotational field can be generated which, on the one hand, exerts a torque on the rotor 3 which effects its rotation and which, on the other hand, exerts a shear force on the rotor 3 which can be set as desired so that its radial position—that is its position in the radial plane perpendicular to the axial direction A. can be actively controlled or regulated. At least three degrees of freedom of the rotor 3 can thus be actively regulated. The rotor 3 is at least passively magnetically stabilized, that is cannot be controlled, by reluctance forces with respect to its axial deflection in the axial direction A. The rotor 3 can also likewise be stabilized—depending on the embodiment—passively magnetically with respect to the remaining two degrees of freedom, namely tilts with respect to the radial plane perpendicular to the desired axis of rotation.

[0060] With a bearingless motor, unlike with classical magnetic bearings, the magnetic support and the drive of the motor is implemented via electromagnetic rotational fields whose sum, on the one hand, generates a drive torque on the rotor 3 as well as a transverse force that can be set as desired and with which the radial position of the rotor 3 can be regulated. These rotational fields can be generated either separately—that is using different coils—or the rotational fields can be generated by superposition by calculation of the required currents or voltages and then with the aid of a single coil system.

[0061] To position the rotor 3 in the mixing tank 2, the mixing tank 2 has at its base 22 a substantially cylindrical bucket 21 that extends outwardly as a bulge with respect to the mixing tank 2 and is arranged at the center of the base 22. The cylindrical bucket 21 is preferably stable in shape and produced from a plastic. The rotor 3 is arranged in the bucket 21.

[0062] The stator 4 is arranged such that it completely surrounds the bucket 21 in the peripheral direction so that the rotor 3 is arranged centrally between the stator poles 43 formed by the coil cores 41.

[0063] The rotor 3 comprises a magnetically effective core 31 that interacts with the stator 4 via magnetic fields to magnetically drive and support the rotor 3. In the present embodiment, the magnetically active core 31 of the rotor 3 is an annular permanent magnet whose magnetization is indicated in FIG. 1 by the two arrows without reference numerals. The magnetically effective core 31 includes a jacket 32 that comprises plastic.

[0064] In the following the magnetic center plane of the magnetically effective core 31 of the rotor 3 is called the magnetic rotor plane C. It is that plane perpendicular to the axial direction A in which the rotor 3 or the magnetically effective core 31 of the rotor 3 is supported in the operating state when the rotor 3 is not tilted. As a rule, the magnetic rotor plane C is the geometrical center plane of the magnetically effective core 31 of the rotor 3 that is disposed perpendicular to the axial direction A. That plane in which the rotor 3 is supported in the operating state is also called the radial plane. The radial plane defines the x-y plane of a Cartesian coordinate system whose z axis extends in the axial direction. If the rotor 3 is therefore not tilted, the radial plane coincides with the magnetic rotor plane C.

[0065] The bucket 21 has a depth in the axial direction that is somewhat larger than the extent of the magnetically effective core 31 of the rotor 3 in the axial direction A. The rotor 3 can thus be raised from the base of the bucket 21 by the magnetic forces on the activation of the electromagnetic rotary drive and can be brought into a centered position between the stator poles 43 where the rotor 3 can then rotate contactlessly with respect to the bucket 21.

[0066] The stator 4 is arranged in a substantially cylindrical separating can 5 that has a centrally arranged cut-out 51 that is likewise cylindrical at its upper side in accordance with the representation and that is dimensioned such that it can receive the bucket 21. In the assembled state, the bucket 21 of the mixing tank 2 is arranged coaxially with the separating can 5 or with the recess 51. The dimensions of the separating can 5 and of the bucket 21 are adapted to one another in this respect such that the separating can 5 tightly surrounds the bucket 21 in the assembled state and its jacket surface contacts the jacket surface of the bucket 21.

[0067] The separating can 5 is an integral component of a stator housing 52 or is fixedly connected to the stator housing 52 that receives the stator 4. The stator 4 in this embodiment is molded by a thermally conductive compound in the separating can 52 and is thus fixed in the separating can 52.

[0068] In the embodiment described here, the rotary drive formed by the stator 4 and the rotor 3 is designed as a so-called temple motor. What is characteristic in a design as a temple motor is that the stator 4 comprises a plurality of separate coil cores 41 of which each comprises a bar-shaped longitudinal limb that extends from a first end in the axial direction A up to a second end, with all the first ends—they are the lower ends in accordance with the representation in FIG. 1—being connected to one another by a reflux 44. In this respect, the reflux 44 comprises a plurality of segments of which each connects the respective first end of a coil core 41 to the first end of the adjacent coil core 41. In this respect, the individual coil cores 41 are preferably arranged such that they surround the rotor 3 in a circular manner and are arranged equidistant on this circle. In operation, the rotor 3 is contactlessly magnetically supported between the two ends of the coil cores 41 that have the radially inwardly directed stator poles 43. It is the longitudinal limbs of the coil cores 41 that are mutually aligned in parallel with one another, that extend in parallel with the axial direction A and that surround the rotor 3 that gave the temple motor its name because these parallel longitudinal limbs are reminiscent of the columns of a temple.

[0069] It is a further feature of the temple motor that the windings 42 of the stator 4 are each arranged around the longitudinal limbs of the coil cores 41 and are thus arranged outside the magnetic rotor plane C; beneath the magnetic rotor plane C in accordance with the representation. The windings 42 are preferably arranged beneath the magnetically effective core 31. The windings 42 are therefore not arranged in the plane in which the rotor 3 is driven and supported in the operating state. Unlike other electromagnetic rotary drives in which the windings of the stator are arranged such that the coil axes each lie in the magnetic rotor plane, that is in the plane in which the rotor is driven and supported, in the temple motor, the windings 42 of the stator 2 are arranged such that the axes of the windings 42 stand perpendicular on the magnetic rotor plane C and are thus aligned in parallel with the axial direction A.

[0070] It is naturally understood that the invention is not restricted to such embodiments as temple motors. Numerous other designs of the stator 4 are also possible. It is only essential that the rotor 3 can be contactlessly magnetically be driven to rotate about the axial direction in the operating state.

[0071] In accordance with the invention, the mixing apparatus 1 has a bar 8 extending in the axial direction A and a mechanical limiting element 9 that is fixed with respect to the mixing tank 2 and that cooperates with the bar 8 to at least limit a tilt of the robot 3 in the operating state. It is in this respect meant by a tilt of the rotor 3 that the magnetic rotor plane C of the rotor no longer stands exactly perpendicular on the axial direction A, but rather includes an angle different than 90° with it. This is equivalent to the fact that the magnetic rotor plane C and the radial plane in which the rotor 3 is supported are no longer congruent and are no longer parallel with one another, but rather include an angle different from zero with one another.

[0072] An axial tilt of the rotor 3 means that the non-tilted rotor 3 is displaced in the axial direction A without being tiled in so doing. In this case, the magnetic rotor plane C is parallel with the radial plane, but no longer congruent therewith.

[0073] The bar 8 extending in the axial direction A is rotationally fixedly connected to the rotor 3 and cooperates with the limiting element 9 fixed with respect to the mixing tank 2. Two different embodiments are generally possible in this respect.

[0074] In accordance with a first preferred embodiment, the limiting element 9 is configured as a tilt limitation 91. This means that the bar 8 rotates free of contact with respect to the tilt limitation 91 in the operating state with a non-tilted rotor 3—that is when the magnetic rotor plane C of the rotor 3 is perpendicular to the axial direction A. Only on a tilt of the rotor 3 does the bar 8 come into physical contact with the limiting element 9 configured as a tilt limitation 91, whereby the tilt of the rotor 3 is limited.

[0075] In accordance with a second preferred embodiment, the limiting element 9 is configured as a mechanical bearing 92 for the bar 8, in particular as a radial bearing. In this second preferred embodiment, the limiting element 9 is therefore a mechanical bearing 92 known per se so that there is also a contact between the limiting element 9 and the bar 8 supported by it with a non-tilted rotor 3.

[0076] The bar 8 can be produced in one piece and with a constant, non-variable length in the axial direction A both in the first and in the second preferred embodiment. It is, however, alternatively also possible that the bar 8 comprises a plurality of parts or segments arranged concentrically in one another, for example tubes that are displaceable relative to one another in the axial direction such that the bar can, like a telescopic antenna, be extended in its length or can be pushed together to the length of the individual parts or segments in a known manner.

[0077] In the first embodiment of the limiting element 9 as a tilt limitation 91, which is shown in FIG. 12, the bar 8 rotates with small clearance free of contact with respect to the limiting element 9 configured as a tilt limitation in the operating state with a non-tilted rotor 3 and a tilt of the rotor 3 is limited by a physical contact between the bar 8 and the limiting element 9.

[0078] In the first embodiment shown in FIG. 1, the cylindrically designed bar 8 is arranged at the center of the rotor 3 so that the axis of the bar 8 coincides with the axial direction A with a non-tilted rotor 3. The bar 8 extends through the total mixing tank 2 with respect to the axial direction A. The limiting element 9 is arranged inwardly disposed at the top 23 of the mixing tank, and indeed such that the center of the limiting element 9 is aligned with the center of the rotor 3. The limiting element 9 is designed as a sleeve here whose inner diameter ID is larger than the diameter D of the bar 8. On the assembly of the mixing apparatus 1, the bar 8 is introduced into the limiting element 9, with the length of the bar 8 and its diameter D being dimensioned such that there is a clearance S between the inner wall of the limiting element 9 and the bar 8. The bar 8 is dimensioned with respect to the axial direction A such that it is also received free of contact by the limiting element 9 in the axial direction A.

[0079] The rotor 3 is passively magnetically stabilized, i.e. not controllable, in the stator 4. This means that if a tilt of the rotor 3 occurs in the operating state, magnetic restoring forces are thereby invoked that effect a torque with respect to the axial direction A on the rotor 3 that moves the rotor 3 back into its non-tilted position. These magnetic restoring forces are typically reluctance forces that are generated by the tilt of the rotor 3. This passive magnetic stabilization of the rotor 3 against tilts should also not be influenced by the limiting element 9. The rotor 3 rotates contactlessly in the stator 4 in the operating state and the bar 8 also rotates contactlessly in the limiting element 9 configured as a tilt limitation 91 with a tilt-free rotor 3. If a tilt of the rotor 3 occurs in operation, it is first compensated by the passive magnetic stabilization of the rotor 3 that moves the rotor 3 back into its non-tilted position without there being any physical contact between the bar 8 and the limiting element 9.

[0080] Only when the tilt of the rotor 3 becomes too great or too strong does a physical contact between the limiting element 9 configured as a tilt limitation 91 and the bar 8 occur that then limits the maximum tilt of the rotor 3. A further increase in the tilt of the rotor 3 is prevented by this physical contact with the limiting element 9.

[0081] In this first preferred embodiment of the limiting element 9 as a tilt limitation 91, it is characteristic that the bar 8 can rotate contactlessly in the limiting element 9 with a non-tilted rotor 3 and on tilts of the rotor 3 that can be reversed by its passive magnetic support. Only when the tilt of the rotor 3 could become too large does the physical contact between the bar 8 and the limiting element 9 prevent a further increase in the tilt of the rotor 3.

[0082] The tilt limitation 91 is thus not a fully-fledged bearing for the rotor 3, but only a limit for the tilt of the rotor 3.

[0083] The clearance S between the bar 8 and the tilt limitation 91 is preferably dimensioned such that the bar 8 comes into contact with the tilt limitation 91 before the rotor 3 comes into physical contact with the wall or the base of the bucket 21. How much the rotor 3 can be tilted before such a contact with the bucket 21 comes about can be determined in a simple manner. The clearance S can then be selected such that a contact between the rotor 3 and the bucket 21 is reliably avoided.

[0084] The bar 8 is preferably also manufactured from plastic and can either be molded to the jacket 32 of the rotor 3 as an integral component or—as the representation in FIG. 1 shows—the bar 8 is manufactured as a separate component that is then plugged into a central opening of the rotor 3 such that the bar 8 is rotationally fixedly connected to the rotor 3. It is naturally also possible to adhesively bond or weld the bar 8 to the rotor 3. It is furthermore possible that the bar 8 comprises a metal, for example a stainless steel or aluminum. As already mentioned, the bar 8 can be configured in one piece with a non-variable length in the axial direction A or the bar 8 comprises a plurality of segments that are arranged concentrically in one another and that are movable relative to one another in the axial direction A so that the bar 8 can be pushed together or pulled apart in the manner of a telescope. The tilt limitation 91 preferably comprising plastic can be manufactured as a separate component and can then be fixed to the top 23 of the mixing tank 2, for example by welding or adhesive bonding. It is naturally also possible that the tilt limitation 91 is manufactured as an integral component of the top 23. The tilt limitation 91 can naturally also fully or partly comprise a metal material.

[0085] In the first embodiment shown in FIG. 1, a plurality of vanes 6 for mixing or stirring the substances are disposed in the mixing tank 2. The vanes 6 are preferably manufactured from plastic and are arranged at and fastened to the bar 8. In this respect, the vanes 6 are arranged at different levels with respect to the axial direction A so that the vanes 6 are distributed over the total mixing tank 2 in the axial direction A. A particularly homogeneous intermixing of the substances in the mixing tank 2 can hereby be implemented. Since the bar 8 having the vanes 6 fastened thereon is rotationally fixedly connected to the rotor 3, the vanes 6 can be driven to rotate about the axial direction A by the rotation of the rotor 3. The vanes 6 can be produced as separate components that are then connected to the bar 8, for example by welding or adhesive bonding, or the vanes 6 can be integral components of the bar 8.

[0086] Unlike the embodiment shown in FIG. 1, it is naturally also possible that all the vanes 6 are combined to form an impeller and one or more such impellers are disposed at the bar 8. It is furthermore possible, alternatively or additionally, to provide the vanes directly on the rotor 3 or directly on the jacket 32 of the rotor.

[0087] As already mentioned, in accordance with a second preferred embodiment, the limitation element 9 can also be configured as a mechanical bearing 92 that forms a fully-fledged bearing, in particular a fully-fledged bearing for the bar 8. In the following, only the differences will be explained for the first embodiment shown in FIG. 1 that result when the limiting element 9 in accordance with the second embodiment is a mechanical bearing 92. Otherwise the preceding explanations also apply in the same or in accordingly the same manner to this second preferred embodiment.

[0088] FIG. 2 shows in a very schematic representation a part of the top 23 of the mixing tank 2 with the fastening element 9 that is fastened thereto and that is configured as a mechanical bearing 92 as well as the end of the bar 8 that is supported by the mechanical bearing 92. It is preferred in this respect if the bearing 92 is primarily configured as a radial bearing and not as an axial bearing for the bar 8. The mechanical bearing 92 in accordance with FIG. 2 is configured as a roller element bearing that comprises, in a manner known per se, an inner bearing body 921 that is rotationally fixedly connected to the bar 8 such that the inner bearing body 921 rotates together with the bar 8, an outer bearing body 922 that is stationary with respect to the mixing tank 2, that is, for example, is fixed to the top 23, and a plurality of rolling elements 923 that are arranged between the inner bearing body 921 rotating in the operating state and the stationary outer bearing body 922. In this respect the rolling elements 923 can all have configurations known from roller element bearings. The rolling elements 923 can in particular be balls (ball bearings) or also cylindrical or conical or frustoconical rolling elements 923. The bar 8 is supported in a manner known per se by the mechanical bearing 92. Unlike the first preferred embodiment, the bar 8 is therefore constantly—also with a non-tilted rotor 3—in physical contact with the mechanical bearing 92 during operation.

[0089] There are naturally a number of variations with respect to the design of the mechanical bearing 92; it is also by no means necessary that the mechanical bearing 92 is designed as a roller element bearing. It is thus, for example, also possible to configure the mechanical bearing 92 as a slide bearing or as a fluid-lubricated bearing or as a hydrodynamic bearing.

[0090] FIG. 3 shows a particularly simple variant in which the mechanical bearing 92 is configured as a slide bearing. The bearing 92 is in this respect configured as a sleeve fixed to the cover 23 of the mixing tank 2 and receiving the end of the bar 8. In this respect, the inner diameter of the sleeve is substantially of the same size as the diameter of the bar 8 so that the bar 8 slides long the inner wall of the sleeve during operation. The axial end of the bar 8, more precisely its axial end surface, is in this respect not in contact with the sleeve, but only the jacket surface of the bar 8. The variant of the mechanical bearing 92 shown in FIG. 3 substantially corresponds in a design aspect to the limiting element 9 shown in FIG. 1, but with the clearance S between the sleeve of the bearing 92 and the bar 8 being zero or being at least almost zero in the embodiment shown in FIG. 3 so that a slide seal is realized. All the materials typical for slide seals are suitable as materials for the counter-moving partners, namely the sleeve of the bearing 92 and the bar 8; for instance, the sleeve of the bearing 92 and the bar 8 can, for example, be produced from a plastic, with different plastics naturally also being able to be used for both components 92, 8. The sleeve of the bearing 92 can, for example, be produced from the materials know under the brand name of Teflon, polytetrafluorotheylene (PTFE) or perfluoralkoxy polymers (PFA) that have good sliding or rubbing properties. However, other material pairs are also suitable, for example metal/polyethylene (PE) or other combinations of metal/plastic. In this respect, the bar 8 is then preferably produced from a metal and the sleeve of the bearing 92 from a plastic. Bearings or sleeves and bars that do not comprise fluoropolymers such as PTFE or PFA or do not comprise parts of these materials are particularly suitable when the mixing apparatus 1 or parts thereof should be sterilized using gamma rays.

[0091] In the second preferred configuration of the limiting element 9 as a mechanical bearing 92, it is in particular preferred if the mechanical bearing 92 is configured as a pendulum bearing that can additionally take up tilts of the bar 8. Pendulum bearings per se are known in numerous embodiments. As an example, FIG. 4 illustrates the basic design of an embodiment in which the mechanical bearing 92 is configured as a pendulum ball bearing, that is as a roller element bearing. The inner bearing body 921, that is rotationally fixedly connected to the bar 8 rotating in the operating state, is substantially cylindrical, whereas the inwardly disposed limitation surface of the stationary outer bearing body 922, that faces the inner bearing body 921, is curved, and in particular spherically curved. If now, a tilt of the bar 8 takes place, the rolling elements 923 configured as balls can roll off on the curved limitation surface of the outer bearing body 922 as is indicated by the arrows with the reference symbol P in FIG. 4. In this manner, the pendulum ball bearing can also take up or compensate tilt moments that are introduced into the bearing 92 by a tilt of the bar 8.

[0092] The rolling elements 923 can also alternatively be configured in a manner known per se in the form or rolls or cylinders in the configuration as a pendulum bearing. It is also preferred in the configuration of the mechanical bearing 92 as a slide bearing if the mechanical bearing 92 is configured as a pendulum bearing. In principle, all known embodiments of pendulum sliding bearings such as spherical slide bearings or joint slide bearings per se are suitable for this.

[0093] A particularly simple embodiment of the mechanical bearing 92 as a pendulum slight bearing is shown in a schematic representation in FIG. 5. In addition, FIG. 6 shows a section along the line VI-VI in FIG. 5.

[0094] In the embodiment shown in FIGS. 5 and 6, the limiting element 9 configured as a mechanical bearing 92 is arranged outwardly disposed at the top 23 of the mixing tank 2, that is outside the mixing tank 2. It is naturally understood that the limiting element 9 or the bearing 92 can in accordingly the same manner also be arranged inwardly disposed at the top 23 or at the base 22 of the mixing tank 2.

[0095] In the embodiment in accordance with FIG. 5 and FIG. 6, the outer bearing body 922 of the mechanical bearing 92 is configured as a disk 922′, for example as a circular disk 922′, that has an opening 925 at its center through which the bar 8 extends. The bar 8 in this embodiment itself forms the inner bearing body. In this respect, the opening 925 in the disk 922′ is dimensioned with respect to its diameter such that the bar 8 contacts the inwardly disposed boundary of the opening 925 so that a slide bearing is hereby realized. The boundary of the opening 925 is preferably configured in rounded form such as is shown in FIG. 5. This embodiment shown in FIG. 5 and FIG. 6 represents a simple pendulum bearing because the bar 8 can carry out tilt movements in the opening 925. The two counter-moving partners can also both be produced from plastic in the configuration as pendulum slide bearings 92 or one of the two counter-moving partners can be produced from metal and the other from plastic.

[0096] The disk 922′ is here attached to the outside of the mixing tank 2, namely to its top 23, and can, for example, be fastened to the top 23 of the mixing tank 2 by adhesive bonding or welding. So that no liquid or no gas can exit the mixing tank 2 along the bar 8 into the environment during operation, a closure cap 926 is disposed at the disk 922′ that is preferably manufactured from a plastic and that completely surrounds the end of the bar 8 at the top in accordance with the illustration. The closure cap 926 is connected to the disk 922′ in a fluid-tight manner, for example by adhesive bonding, welding or another otherwise sealing connection, e.g. a snap-in connection.

[0097] So that the bar 8 cannot slip out of the opening 925 during operation and is thus secured against a separation from the mechanical seal 92, the bar 8 preferably has, at its end remote from the rotor 3, a terminating element 91 whose diameter is larger than the diameter of the opening 925. In the assembly of the bar 8, this terminating element 81 can be moved through the opening 925 due to elastic deformations.

[0098] The now following explanations of further embodiments and variants of the invention apply in the same manner or in accordingly the same manner both to the first preferred embodiment in which the limiting element 9 is configured as a tilt limitation 91 and to the second preferred embodiment in which the limiting element 9 is configured as a mechanical bearing 92. Reference is therefore made in the following—apart from explicitly mentioned exceptions—generally to the limiting element 9, with this being able to be configured in each case both as a tilt limitation 91 and as a mechanical bearing 92.

[0099] FIG. 7 shows in a longitudinal section along the axial direction A a second embodiment of the mixing apparatus in accordance with the invention. In the following, only the differences from the above-described first embodiment will be looked at. The reference numerals in particular have the same meaning as has already been explained in connection with the first embodiment described above. It is understood that all the above explanations also apply in the same manner or accordingly in the same manner to the second embodiment.

[0100] The second embodiment shown in FIG. 7 is here configured as a bioreactor. Unlike the first embodiment, the rotor 3 and the stator 4 are arranged at the top 23 of the mixing tank 2 in the second embodiment. The bucket 21 is arranged at the center of the top 23 and is in turn configured—with respect to the mixing tank 2—outwardly as a protuberance. The separating can 5 having the stator 4 arranged therein is accordingly arranged outwardly on the top 23 so that its recess 51 receives or surrounds the bucket 21 with the rotor 3 arranged therein in accordingly the same manner as was already described for the first embodiment.

[0101] The limiting element 9 is fixed opposite the center of the rotor 3 at the base 22 of the mixing tank 2 such that the limiting element 9 can receive the end of the bar 8.

[0102] The mixing tank 2 is arranged in a foot 10 that gives the mixing tank 2 a secure standing.

[0103] Further components of the mixing apparatus 1 that can e.g. be provided in an embodiment as a bioreactor are now also shown with an exemplary character in FIG. 7. A feed 26 is thus provided that extends through the wall of the mixing tank 2 and through which substances can be introduced into the mixing tank 2. A gas feed 25 is furthermore provided that extends through the wall of the mixing tank 2 and through which a gas, for example oxygen, can be introduced into the mixing tank 2. A gas feed 24 having a gas filter is furthermore provided that extends through the wall of the mixing tank 2. Gases such as carbon dioxide that are generated during biological processes in the mixing tank 2 can be led out of the mixing tank via the gas drain line 24. A further leadthrough 27 is also provided that extends through the wall of the mixing tank 2 and that can be used for receiving probes 271 or measurement sensors with which parameters can be monitored during the mixing process, e.g. pH, temperature, pressure, concentrations, etc. A drain line 28 which extends through the wall of the mixing tank 2 and through which substances can be led off from the mixing tank 2 or by which the mixing tank 2 can be emptied is provided at the base 22 of the mixing tank 2. Further leadthroughs 29 can also be provided that can be used for different purposes.

[0104] FIG. 8 shows in a longitudinal section along the axial direction A a third embodiment of the mixing apparatus 1 in accordance with the invention. In the following, only the differences from the above-described embodiments will be looked at. The reference numerals in particular have the same meaning as has already been explained in connection with the embodiments described above. It is understood that all the above explanations also apply in the same manner or accordingly in the same manner to the third embodiment.

[0105] The third embodiment essentially differs from the first two embodiments in that the bar 8 does not extend through the total mixing tank 2 with respect to the axial direction A, but rather ends within the mixing tank 2, that is considerably spaced apart from its top 23.

[0106] The limiting element 9 is here disposed at and fixed to the base 22 of the mixing tank 2. For better understanding, FIG. 9 shows a plan view of the limiting element 9 of the mixing apparatus 1 shown in FIG. 8. The limiting element 9 comprises a central ring 93 for receiving the bar 8.

[0107] In this respect, in the case of the first preferred embodiment of the limiting element 9 as a tilt limitation 91, the inner diameter ID of the ring 93 is larger than the diameter D of the bar 8. On assembling the mixing apparatus 1, the bar 8 is led through the ring 93, with the diameter D of the bar being dimensioned such that the clearance S that is fixed by the difference of the inner diameter ID of the ring 93 and the diameter D of the bar 8 is present between the inner wall of the ring 93 and the bar 8. In this embodiment, the bar 8 therefore extends through the limiting element 9 in the axial direction A.

[0108] In the case of the second preferred embodiment of the limiting element 9 as a mechanical bearing 92, the inner diameter ID of the ring 93 is the same size or almost the same size as the diameter of the bar 8 so that the clearance S is zero or approximately zero. The ring 93 then forms a mechanical slide bearing 92 for the bar 8, preferably a fluid-lubricated slide bearing 92 that is lubricated by the process fluid or by one of the process fluids that is/are located in the mixing tank 2 in the operating state. It can be advantageous in this respect if a ring-shaped insert (not shown) is disposed in the ring 93 and is produced from a material particularly suitable for sliding friction, for example a plastic such as the already mentioned Teflon.

[0109] For both preferred embodiments, namely as a tilt limitation 91 or as a mechanical bearing 92, the limiting element 9 furthermore comprises a plurality of arms 94, four here, that start, equidistantly distributed, in each case at the radially outer margin of the ring 93 and extend from there first in the radial direction and then in the axial direction A up to the base 22 of the mixing tank 2 where they are each fixed. Depending on how long the bar 8 is, the arms 94 of the limiting element 9 can also be fixed to the top 22 of the mixing tank 2.

[0110] It is naturally also possible in such embodiments in which the bar 8 does not extend through the whole mixing tank 2 with respect to the axial direction A to design the limiting element 9 such that it receives an end of the bar 8 and is not fully penetrated by the bar 8.

[0111] FIG. 10 shows in a longitudinal section along the axial direction A a fourth embodiment of the mixing apparatus 1 in accordance with the invention. In the following, only the differences from the above-described embodiments will be looked at. The reference numerals in particular have the same meaning as has already been explained in connection with the embodiments described above. It is understood that all the above explanations also apply in the same manner or accordingly in the same manner to the fourth embodiment.

[0112] The fourth embodiment of the mixing apparatus 1 in accordance with the invention is specifically designed for applications with a single use. To ensure the purity or the sterility of those components of the mixing apparatus 1 which come into contact with the substances to be mixed or stirred, the fourth embodiment comprises a single-use apparatus which is designated as a whole by the reference numeral 20 and is configured for a single use and comprising a reusable apparatus which is designated as a whole by the reference numeral 60 and which is configured for permanent use, that is for multiple use. In this respect, the single-use apparatus 20 comprises those components which come into contact with the substances to be mixed during the mixing process. That is, in particular the mixing tank 2, the rotor 3, all the vanes 6, the bar 8 and the limiting element 9.

[0113] In this respect those components or parts are meant by the term “single-use apparatus” and other compound words having the element “single-use” such as single-use part, single-use component, etc. which are configured for single use, that is which are used only one single time as intended and are then disposed of. A new, previously unused single-use part then has to be used for a new application. In the design or configuring of the single-use apparatus 20, essential aspects are therefore that the single-use apparatus 20 can be manufactured as simply and economically as possible, causes few costs and can be manufactured from materials which are available as inexpensively as possible. Another important aspect is that the single-use apparatus 20 can be assembled in as simple a manner as possible with the reusable apparatus 60 to form the mixing apparatus 1. The single-use apparatus 20 should therefore be able to be replaced in a very simple manner without a high installation effort being required for this purpose. The single-use apparatus 20 should particularly preferably be able to be assembled with or separable from the reusable apparatus 60 without using tools.

[0114] It is also an important aspect that the single-use apparatus 20 can be disposed of as simply as possible after its use. Those materials are therefore preferred which bring about environmental pollution which is as low as possible, in particular also during their disposal.

[0115] In the design of the single-use apparatus 20, the mixing tank 2 is designed as a flexible mixing tank 2 that is manufactured from a plastic. The mixing tank 2 is preferably a flexible pouch, for example a plastic sack or a sack of a synthetic material, which can be folded together so that it takes up as little space as possible during storage. The mixing tank 2 in the fourth embodiment has a plurality of inlets or outlets 11 that, as described above, can be used, for example, for feeding and draining substances and gases or for the reception of probes or measurement sensors. In this respect, for example, hoses or hose-like continuations are provided at some of the inlets or outlets 11 in a manner known per se; they are manufactured from plastic and are welded to the mixing tank 2 such that substances can be fed or drained through these hoses. Other inlets or outlets 11 can also be designed as self-sealing passages in a manner known per se.

[0116] So-called sampling ports 111 can in particular be adhesively bonded or welded to the mixing tank 2. They are in this respect short hose-like plastic structures through which, for example, samples can be removed from the mixing tank 2. Each sampling port 111 is in this respect typically secured in a manner known per se by a clamp at its end projecting from the mixing tank 2 such that no unwanted substances can move through these sampling ports 111 into the interior of the mixing tank 2.

[0117] The gas drainage line 24 having the gas filter can also be provided at the mixing tank 2, with the gas filter also being configured for single use.

[0118] The cylindrical bucket 21 for the reception of the rotor 3 is preferably of stable shape and is produced from a plastic. However, it can also, for example, be designed in the form of a flexible hose or pouch composed of a plastic film. The limiting element 9, the bar 8 and all the vanes 6 are designed as stable in shape and are preferably produced from a plastic. The shape-stable parts that are fixed to the mixing tank 2, that is in particular the bucket 21 and the limiting element 9, can be connected to the flexible mixing tank 2 in a fluid-tight manner by adhesive bonding or welding. It is naturally also possible in the design for single use to manufacture the bar 8 and/or the limiting element 9 fully or partly from a metal material. The limiting element 9 can thus, for example, be a metal sleeve, e.g. of aluminum. The bar 8 can also comprise a metal material in the design for single use to ensure a greater stability, for example. Since both the limiting element 9 and the bar 8 are components of a very simple design, in particular with respect to their geometry, they can also be manufactured very inexpensively.

[0119] The reusable apparatus 60 comprises a stable-shape support tank 61 for receiving the mixing tank and comprises the stator 4. The support tank 61 has a plurality of feet 62 on which the support tank 61 stands at its base. At least one opening 12 is furthermore disposed in the base so that substances can be drained out of the mixing tank 2 or can be introduced into it. The substantially cylindrically designed support tank 61 is open at its upper side or optionally—as shown in FIG. 10—includes a removable cover 63 so that the mixing tank 2 can be introduced into the support tank 61 without problem. Windows 64 can furthermore be provided at the wall of the support tank 61 and an optical access to the mixing tank 2 is possible through them.

[0120] The substantially cylindrically designed separating can 5 and the stator housing 52 having the sensor 4 contained therein are centrally arranged at the base of the support tank 61. The separating can 5 is integrated in the stator housing 52 or is fixed thereto. The separating can 5 extends downwardly in accordance with the illustration in the direction of its cylinder axis such that it can coaxially receive the bucket 21 in the assembled state. The dimensions of the separating can 5 and of the bucket 21 are adapted to one another in this respect such that the recess 51 of the separating can 5 tightly surrounds the bucket 21 in the assembled state and its jacket surface contacts the jacket surface of the bucket 21.

[0121] The stator housing 52 having the separating can 5 is preferably fixed to the base of the support tank 61 by screws.

[0122] The stator 4 is arranged in the separating can 52 and is designed as a bearing and drive stator by which the rotor 3, in the operating state, can be driven contactlessly and can be magnetically contactlessly supported with respect to the stator 3.

[0123] The assembly of the single-use apparatus 20 and of the reusable apparatus 60 to form the mixing apparatus 1 is extremely simple and can be carried out fast and in particular without tools. For this purpose, the mixing tank 2 that is typically folded together for storage or is wound around the bar 8 and that has the rotor 3 located thereat, the limiting element 9 and the vanes 6 is removed from its packaging and is placed into the support tank 61 and the bucket 21 having the rotor 3 is inserted into the separating can 5. If the bar 8 is not yet connected to the rotor 3, the bar 8 is inserted into the rotor 3 and is then brought into active connection with the limiting element 9. The cover 63 is optionally placed on to close the support tank 61. The mixing apparatus 1 is then already ready for use. After use, the mixing tank 2 having the bucket 21, the bar 8, the limiting element 9 and the rotor 3 is simply pulled out of the support tank 61. The bucket 21 in this respect simply releases from the separating can 5. This particularly simple and problem-free connection or separation of the single-use apparatus 20 to or from the reusable apparatus 60 thus takes account of a substantial aspect of the embodiment for the single use.

[0124] It can in particular be advantageous in the design of the mixing tank 2 as a flexible mixing tank 2 if the limiting element 9 comprises a fixing 90 by which the limiting element can be fixed with respect to the reusable apparatus 60. In the embodiment shown in FIG. 10, this fixing 90 comprises a pin or a threaded pin that engages through a corresponding opening in the cover 63 of the reusable apparatus 60 and is then fixed to the cover 63 by a nut or of another suitable measure.

[0125] The rotor 3 can—as shown in FIG. 10—be designed with a permanent magnet as a magnetically effective core 31. It can, however, also in particular be advantageous in the design as a single part in dependence on the application to design the rotor 3 as free of permanent magnets, that is without permanent magnets and free of coils. The magnetically effective core 31 is then, for example, produced from a soft-magnetic material such as iron, nickel-iron or silicon-iron. This measure allows an inexpensive embodiment of the rotor 3 as a single-use part since in particular no rare earths such as neodymium or samarium or compounds or alloys thereof are necessary for the production of the rotor 3 which are frequently used for the manufacture of permanent magnets.

[0126] In such embodiments in which the rotor 3 is designed without permanent magnets, it is particularly preferred if one or more permanent magnets are provided in the stator 4 to generate a permanent magnetic premagnetization flux such that the total magnetic flux required for the drive and for the support does not have to be generated as an electromagnetic flux.

[0127] Since the components of the single-use apparatus 20, that is the mixing tank 2, the rotor 3, all the vanes 6, the bar 8, and the limiting element 9 are configured for single use, the parts produced from plastic should be manufactured from a commercial plastic that is as inexpensive as possible. A further substantial aspect is that the single-use apparatus 20 or its components has/have to be able to be sterilized for certain fields of application. In this respect, it is particularly advantageous if the single-use apparatus 20 can be gamma sterilized. In this type of sterilization, the element to be sterilized is acted on by gamma radiation. The advantage of the gamma sterilization, for example in comparison with steam sterilization, in particular lies in the fact that the sterilization can also take place through the packaging. It is common practice especially with single-use parts that the parts are brought into the packaging after their manufacture and are then stored for some time before they are delivered to customers. In such cases, the sterilization takes place through the packaging, which is not possible with a steam sterilization or another method.

[0128] The single-use apparatus 20, on the other hand, offers the great advantage due to its only single usability that no value has to be placed on a good cleaning capability of the single-use apparatus 20 in the construction because the single-use apparatus does not have to be cleaned when used as intended. It is furthermore not necessary as a rule that the single-use apparatus 20 or its components have to be sterilized more than once. This is in particular a great advantage with the gamma sterilization because the application of gamma radiation to plastics can result in degradations so that a multiple gamma sterilization can make the plastic unusable.

[0129] Since as a rule a sterilization at high temperatures and/or at a high (steam) pressure can be dispensed with for single-use parts, less expensive plastics can be used, for example those which cannot withstand high temperatures or which cannot be exposed to high temperature values and high pressure values a multiple of times.

[0130] When taking all these aspects into account, it is therefore preferred to use those plastics for the manufacture of the single-use apparatus 20 which can be gamma sterilized at least once. The materials should in this respect be gamma-stable for a dose of at least 40 kGy to allow a single-time gamma sterilization. In addition, no toxic substances should arise in the gamma sterilization. It is additionally preferred for all materials which come into contact with the substances to be mixed to satisfy USP Class VI standards.

[0131] The following plastics are, for example, preferred for the manufacture of the flexible mixing tank 2: Polyethylenes (PE), low density polyethylenes (LDPE), ultra low density polyethylenes (ULDPE), ethylene vinyl acetates (EVA), polyethylene terephthalates (PET), polyvinylchloride (PVC), polypropylenes (PP), polyurethanes (PU), silicones.

[0132] The following plastics are, for example, preferred for the manufacture of the bucket 21, of the bar 8, of the limiting element 8, of the vanes 6 and of the parts of the rotor 3 comprising plastic, that is e.g. the jacket 32: Polyethylenes (PE), polypropylenes (PP), low density polyethylenes (LDPE), ultra low density polyethylenes (ULDPE), ethylene vinyl acetates (EVA), polyethylene terephthalates (PET), polyvinylchloride (PVC), polyvinylidene fluorides (PVDF), acrylonitrile butadiene styrenes (ABS), polyacrylics, polycarbonates (PC).

[0133] These named plastic are inter alia also suitable for the manufacture of a shape-stable mixing tank 2 that is designed for multiple use.

[0134] Less suitable materials or even unsuitable materials for the manufacture of the plastic parts of the single-use apparatus 20 are, for example, the materials known under the trade name Teflon polytetrafluroethylenes (PTFE) and perfluooralkoxy polymers (PFA). There is namely the risk with these materials on gamma sterilization that hazardous gases arise such as fluorine which can then form toxic or harmful compounds such as hydrofluoric acid (HF).

[0135] If the mixing tank 2 is designed for multiple use, it can naturally also be manufactured from PTFE or PFA or also from a metal, for example from stainless steel or also from glass.

[0136] It is also preferred if the components comprising plastic can be manufactured by an injection molding process because this is a particularly inexpensive kind of manufacture.

[0137] Different variants for the design of the limiting element 9 that are suitable for all the above-described embodiments will be explained in the following by way of example with reference to FIGS. 11, 12 and 13. As already explained, the bar 8 and the limiting element 9 preferably cooperate such that the bar 8 is secured against a separation from the limiting element 9. In addition to the variant already described with the ring 93 of the limiting element 9 in which the bar 8 extends in the axial direction through the limiting element 9, FIGS. 11 to 13 show embodiments in which the limiting element 9 cooperates with the end of the bar 8 remote from the rotor 3.

[0138] In the variants shown in FIGS. 12 and 13, the limiting element 9 is designed in this respect such that the end of the bar 8 remote from the rotor 3 is received by the limiting element 9, whereas the variant shown in FIG. 11 corresponds to an embodiment in which the end of the bar 8 remote from the rotor 3 is designed such that it surrounds a part of the limiting element 9.

[0139] The variant of the limiting element 9 shown in FIG. 11 comprises a pin 95 that projects out of a base body 96 of the limiting element 9 in the axial direction A. This pin 95 has at its end remote from the base body 96 a spherical head 97 that is designed to cooperate with the bar 8. The end of the bar 8 cooperating with this pin 95 is hollow and comprises a tongue 82 at its end that bounds the opening of the bar 8 such that the passage formed by the tongue 82 is, on the one hand, larger than the diameter DS of the pin and, on the other hand, smaller than the diameter of the spherical head 97. The spherical head 97 can thus be introduced in the form of a snap-in connection into the end of the bar 8.

[0140] In the first preferred embodiment of the limiting element 9 as a tilt limitation 91, the diameter of the spherical head 97 is dimensioned such that the spherical head 97 is received free of contact in the end of the bar 8 after its introduction into the end of this bar 8 as long as the rotor 3 is not tilted or is oriented in a tilt that can be compensated by the passively magnetic support. The spherical head 97 only contacts the inner wall of the bar 8, rolls off thereon and thus limits the maximum possible tilt of the rotor 3 when the tilt of the rotor 3 becomes too strong or too large. The tilt of the root 3 is indicated by the double arrow without a reference numeral in FIG. 11.

[0141] In the second preferred embodiment of the limiting element 9 as a mechanical bearing 92, the diameter of the spherical head 97 is dimensioned such that the spherical head 97 constantly contacts the inner wall of the bar 8—that is also with a non-tilted rotor 3—after its introduction into the end of the bar 8 and thus cooperates with this inner wall in the form of a slide bearing.

[0142] The variants for the limiting element 9 shown in FIGS. 12 and 13 are variants in which the end of the bar 8 remote from the rotor 3 is received by the limiting element 9. In these two variants, the bar 8 has at its end remote from the rotor 3 the terminating element 81 that is designed for receiving the limiting element 9. In this respect, the active connection between the end of the bar 8 and the limiting element 9 is preferably implemented by a snap-in connection.

[0143] In the variant shown in FIG. 12, the terminating element 81 is frustoconical. This embodiment is in particular suitable for the first preferred embodiment of the limiting element 9 as a tilt limitation 91. The limiting element 9 then has a region designed as a claw 98 and having a central inlet opening 982 that is dimensioned such that the diameter of the inlet opening 982 is larger than the diameter D of the bar 8, but is smaller than the maximum diameter of the frustoconical terminating element 81. The claw 98 forms a conical surface 981 around the inlet opening 982 through which the terminating element 81 can be introduced into the limiting element 9. A cavity 99 is provided beneath the claw 98 and is designed such that the terminating element 81 can move contactlessly in the cavity 99 as long as the tilt of the rotor 3 does not exceed the predefinable limit value that is given by the capacity of the passively magnetic stabilization of the rotor 3. If this limit value is exceeded, the terminating element 81 comes into physical contact with the limiting element 9 and thus prevents a further increase in the tilt of the rotor 3. It is advantageous in this respect that the frustoconical terminating element 81 can roll off at the inner surface of the limiting element 9.

[0144] The variant shown in FIG. 13 shows an embodiment in which the terminating element 81 is designed as a spherical head. In the first embodiment of the limiting element 9 as a tilt limitation 91, the diameter of the spherical head 81 is dimensioned such that the spherical head 81 is received free of contact in the cavity 99 after its introduction into the claw 98 as long as the rotor 3 is not tilted or is oriented in a tilt that can be compensated by the passively magnetic support. The spherical head 81 only contacts the inner wall of the cavity 99, rolls off thereon and thus limits the maximum possible tilt of the rotor 3 when the tilt of the rotor 3 becomes too strong or too large. The tilt of the root 3 is indicated by the double arrow without a reference numeral in FIG. 13.

[0145] If the variant shown in FIG. 13 in accordance with the second preferred configuration of the limiting element 9 is configured as a mechanical bearing 92, the diameter of the spherical head 81 is dimensioned such that the spherical head 81 constantly contacts the wall of the cavity—that is also with a non-tilted rotor 3—after its introduction into the cavity 99 and thus cooperates with this wall in the form of a slide bearing.

[0146] The limiting element 9 that is preferably of stable shape can—as shown in FIG. 13—be connected to the mixing tank 2 by welding or adhesive bonding and can be fixed with respect thereto.

[0147] The variants shown in FIGS. 12 and 13 in particular provide the additional advantage that the displacement of the rotor 3 in the axial direction A is also limited by this design, and indeed both for upward displacements of the rotor 3 in the axial direction A and for downward displacements of the rotor 3 in the axial direction A.

[0148] FIG. 14 shows a variant that is in particular suitable for the second preferred configuration of the limiting element 9 as a mechanical bearing 92. This variant accordingly corresponds approximately to that shown in FIG. 13, wherein FIG. 14 specifically shows an embodiment as a slide bearing of plastic in which the terminating element 81 configured as a spherical head snaps into the claw 98 such that the axial clearance of the bar 8 is likewise restricted.