ELECTRIC MOTOR AND VACUUM PUMP

Description

[0001] The invention relates to an electric motor with the features according to the preamble of claim 1. The invention further relates to a vacuum pump according to the preamble of claim 13.

[0002] A common industrial design for electric motors is the multi-shaft electric motor, which serves to synchronously drive a number of shafts. A typical application, particularly for twin-shaft electric motors, is in pumps, where two counter-rotating displacement elements generate the pump's delivery rate. Examples include screw pumps, Roots or rotary lobe pumps, and screw compressors. In these pumps, the shafts rotate in opposite directions. The displacement elements, such as screw spindles, mesh as tightly as possible during rotation. However, they must not actually touch, as this would have negative effects during operation, such as increased wear, noise, and power consumption.Especially given the often high rotational speeds of such pumps, precise manufacturing, as well as accurate balancing and alignment of the moving components, is crucial. Due to the required tightness, the gap widths in the area of ​​the displacement elements are extremely small. Therefore, only minimal manufacturing tolerances are permitted, and there are high demands on the synchronization of the rotational movement of both shafts.

[0003] Several approaches for synchronizing both shafts are already known in the art. For example, the shafts can be mechanically coupled, such as by means of a gear drive. In this case, driving only one shaft is often sufficient, with the other shafts driven via the gearbox. However, a disadvantage of this approach is that the mechanical contact of the coupling components leads to the aforementioned problems, namely increased wear, operating noise, and power consumption. Besides the comparatively large space requirement, this solution often necessitates adequate lubrication, which in turn requires a reliable and durable seal to the pumping chamber. Due to the high design complexity, this approach is relatively expensive.

[0004] An alternative is a purely electronic control of the shaft speeds and their relative phase. However, particularly at high speeds, this requires very precise control with low latency. Aside from the need for sufficiently powerful control electronics, the design effort is comparatively high due to the complex sensor system required for each shaft.

[0005] The disadvantages of the aforementioned solutions are partially overcome by an approach that uses a motor in which both shafts are arranged in a common stator field. In this case, the stator field acts simultaneously on two rotor magnet assemblies, each connected to a separate shaft. Thus, both rotor magnet assemblies always experience any fluctuations in the stator field in the same way. This largely prevents corresponding wow and flutter.

[0006] Furthermore, the rotational movement of the shafts is coupled by an adjacent arrangement of the rotor magnet devices, which in this respect form a magnetic transmission.

[0007] To strengthen the coupling in such a magnetic transmission, WO 2004 / 031585 A1 proposes an additional pair of rotor magnet devices on the parallel shafts, which interact with each other in a corresponding manner.

[0008] In order to achieve an automatic and as precise as possible alignment of the rotor magnet devices to each other in the rest position, it is further proposed in EP 2 642 127 A1 that the rotor magnet devices orient themselves independently according to their interacting, complementary magnetic fields by means of free rotation on the shaft before they are firmly connected to the shaft.

[0009] The problem here, however, is that each rotor magnet assembly is subjected to two magnetic fields – the stator field and the magnetic field of the other rotor magnet assembly – which are essentially independent of each other. Since there are limits to the accuracy of adjustment in practice, a situation can arise where, with regard to the alignment of the shafts, the rest position relative to a static stator field does not exactly coincide with the rest position with respect to the magnetic interaction of the rotor magnet assemblies. The field strength of the stator field is generally higher than the coupling effect between the rotor magnet assemblies. Therefore, in the case described above, when the stator field is active, the two shafts are always offset by a certain angle of rotation relative to their rest positions.

[0010] Similar to the case of a tensioned spring, a tension exists between the rotor magnet assemblies in the form of a force that is transmitted to the shafts as a relative torque. This torque persists even with a changing stator field, i.e., when the shaft is driven. During pump operation, minor fluctuations in speed can, in this situation, develop into a superimposed torsional vibration that impairs the synchronous rotation of the shafts and can thus lead to significant malfunctions. Such torsional vibrations are particularly problematic in relatively small systems with relatively long shafts or in systems with only one bearing. Furthermore, plastics such as PEEK are frequently used in the manufacture of pump components due to their chemical resistance.Compared to metallic materials, however, plastics generally have a lower density and higher elasticity, which promotes the formation of vibrations in the material.

[0011] Since the rotation of the shafts cannot be individually controlled electronically in a shared stator field, alternative methods must be used to counteract the disruptive torsional vibration. For example, the amplitude of this torsional vibration can be limited by a normally non-contact, mechanical emergency running gear. Here, relative rotation of the shafts is stopped, for instance, by the contact of meshing gears. However, this leads to considerable noise and, due to gear wear, to increased maintenance requirements after a short time.

[0012] Damping torsional vibration by shifting the resonant frequency would also require, in particular, adjusting the mass of the components involved. However, this approach is not equally effective for all rotational speeds. Furthermore, an overly lightweight design leads to structural instability, while an overly robust design results in an undesirable increase in energy consumption.

[0013] Against this background, the present invention aims to provide an electric motor with two shafts in which the rotation of the shafts is synchronized particularly reliably and in which, in particular, the problems described above are avoided.

[0014] The aforementioned problem is solved by an electric motor with the features according to claim 1 and by a vacuum pump with the features according to claim 13.

[0015] The magnetic bias described above, in the form of a force acting between the rotor magnets of both shafts, can be compensated by at least one adjusting magnet device on each of the two shafts of the electric motor according to the invention. For this purpose, a counter-torque is generated between the two shafts by the magnetic interaction of the adjusting magnet device of one shaft with a complementary adjusting device of the other shaft. This counter-torque preferably acts as a corrective in that, with an active stator field, at least substantially no force acts between the rotor magnets that is based on an angular displacement relative to each other compared to their relative rest position.

[0016] The adjusting magnet device preferably has a similar structure to the rotor magnet devices. For example, the adjusting magnet device comprises at least one magnet whose magnetic poles can interact with the magnetic poles of a magnet in a complementary adjusting magnet device. However, the number, arrangement, and / or orientation of the magnets can vary. A ring-shaped, preferably equidistant, arrangement of magnets or magnetic poles around the shaft has proven particularly suitable.

[0017] With respect to relative rotation, the torque caused by the angular displacement corresponds to the deflection against a spring force in an oscillating system. If the resulting torque is close to zero, the system, even at high speeds, does not tend to develop a superimposed torsional vibration that, depending on resonance conditions, could escalate to a critical level. If the amplitude of such a torsional vibration becomes too large, the magnetic coupling between the rotor magnets can become misaligned, so that the synchronous operation of both shafts is no longer guaranteed. For example, in the case of a pump, this can lead to a collision of rotating displacement elements, which, in addition to increased wear and an increase in operating noise, can also result in pump failure in severe cases.

[0018] If relative fluctuations in speed between the shafts occur during operation, the adjusting magnet devices are rotated relative to each other. According to the invention, this causes an increase in the corrective force between the respective corresponding magnetic poles of the adjusting magnet devices, which counteracts the formation of a torsional vibration without wear.

[0019] The group of all components that rotate with the shaft during operation of the pump is collectively referred to as the "rotor" in connection with the present invention. This includes, in addition to the shaft itself, in particular the rotor magnet devices, adjusting magnet devices, any displacement elements and / or other components associated with the shaft that are connected to the shaft or other parts of the rotor in such a way that they rotate with the electric motor during operation.

[0020] The degree to which the two rotors are misaligned relative to each other with respect to their mutual magnetic interaction, i.e., rotationally displaced, depends primarily on the unavoidable tolerances in the manufacturing of the components and in the assembly of the electric motor. This degree can therefore hardly be predicted precisely. For this reason, at least one of the adjusting magnet devices is rotatably mounted on its corresponding shaft in such a way that it can be adjusted relative to the shaft by means of rotation. Alternatively or additionally, the adjustability of the adjusting magnet device can be expressed by allowing its rotational angular position relative to a complementary adjusting magnet device on the other shaft to be changed. Thus, a specific adjustment of the correction position of the adjusting magnet devices can be made on a case-by-case basis.

[0021] Although it is not strictly necessary for both interacting adjustment magnets of a complementary pair to be adjustable in the aforementioned manner, this is provided for in a preferred embodiment. This facilitates the adjustment of the correct compensating position of the adjustment magnet(s). Furthermore, it can improve the handling of the device, for example, if one of the adjustment magnets is difficult for a user to access due to structural conditions.

[0022] As in the case of the rotor magnet devices, the mutual interaction of the adjusting magnet devices preferably also achieves a coupling of the rotors according to the principle of a magnetic transmission. In addition to their compensating effect, for example to prevent superimposed torsional vibrations, the adjusting magnet devices thus also contribute to stable synchronization of the rotors.

[0023] The adjusting magnet devices can, in addition to the actual magnetically interacting components, i.e., one or more magnets, also include other elements that serve, for example, for attachment to the shaft, holding the magnets together, and / or, in particular, for adjustability in the form of rotation and / or axial displacement. The same applies to the rotor magnet devices.

[0024] The rotors of the electric motor or pump according to the invention can, in addition to the rotor magnet devices arranged in the stator field as part of the drive and the adjusting magnet devices, also have further rotor magnet devices outside the stator, which serve to further magnetically couple the rotors. According to the invention, a combined embodiment of an adjustable adjusting magnet device with a rigid rotor magnet device is also possible. A part that can be adjusted by rotation relative to the shaft preferably fulfills the aforementioned function of the adjusting magnet device, i.e., in particular the static and / or dynamic compensation of an unwanted relative torque between the rotors, while a part rigidly connected to the shaft serves only to reinforce the relative coupling of the rotors.

[0025] It is understood that multiple adjusting magnet devices can be provided for each shaft. The adjusting magnet devices of a shaft are designed differently, for example, by comprising a different number of magnets. This allows for a more precise adjustment of the compensating force or torque in some applications.

[0026] Preferably, at least one of the adjusting magnet devices of each shaft is arranged outside the stator. This prevents the adjusting magnet device from being subjected to any additional force from the stator field. The compensating function of the adjusting magnet device can therefore occur independently of the other forces acting on the rotor.

[0027] Functionally, a distinction must be made between a corrective force acting between the adjusting magnet devices and a coupling force acting between two complementary rotor magnet devices. This distinction is not contradicted by the fact that coupling also occurs through the interaction of complementary adjusting magnet devices. The corrective force results, in particular, from the targeted adjustment of a relative rotation angle between the adjusting magnet devices. During rotor rotation in operation, the corrective force between two adjusting magnet devices preferably behaves out of phase with the coupling force between two rotor magnet devices. A preload with respect to the coupling force can, for example, lead to an acceleration of the rotor's rotational motion, which is then dampened by the out-of-phase corrective force.

[0028] The coupling force nominally serves only to synchronize the rotors. The corrective force, therefore, primarily serves to compensate for errors in the magnitude, orientation, and / or phase of the coupling force. These errors can be either static or dynamic in nature. In the latter case, the compensation prevents, for example, the formation of a superimposed torsional vibration as described above.

[0029] In a preferred embodiment, the corrective force between the complementary adjusting magnet devices is greater than or equal in magnitude to the coupling force acting between two complementary rotor magnet devices. In this way, the compensating corrective force can have a particularly effective effect. Especially when the maximum achievable corrective force is significantly greater than the coupling force, relative speed fluctuations and superimposed torsional vibrations are rapidly damped, preferably before a torsional vibration builds up to a significant degree or the relative rotational displacement of the rotors relative to each other reaches a critical level.

[0030] In its simplest embodiment, a rotor magnet assembly and / or an adjustment magnet assembly of the electric motor according to the invention comprises only one magnet. However, an embodiment with a plurality of magnets is particularly preferred to ensure reliable coupling of the rotors in the case of rotor magnet assemblies and, furthermore, more precise adjustment in the case of adjustment magnet assemblies. The magnet(s) can be installed in or attached to the rotor magnet assembly or adjustment magnet assembly as a whole and / or constructed from individual parts, in the case of a multi-part embodiment, particularly by bonding. The manufacture of the corresponding components is thus possible in a simple and cost-effective manner. Sintered and / or polymer-bonded magnets are preferably used.

[0031] At least one of the rotor magnet assemblies and / or at least one of the adjustment magnet assemblies preferably comprises a magnetic multipole. Since each magnet itself already represents a dipole, the term "magnetic multipole" here refers to configurations comprising at least one magnetic quadrupole, i.e., embodiments in which at least four magnetic poles are provided. However, a higher-order magnetic multipole is particularly preferred, preferably an at least eightfold multipole, more preferably an at least twelvefold multipole, and most preferably an at least twenty-fourfold multipole. According to the invention, however, the number of magnetic poles is not limited. In principle, an n-fold multipole, in the sense of a multipole of any order, can be used. Depending on the number of poles of a rotor magnet assembly or...The adjusting magnet device allows for a correspondingly more precise coupling of the rotors or a finer adjustment of the adjusting magnet device to compensate for the tension described above.

[0032] It is understood that the rotor magnet assemblies and / or adjusting magnet assemblies of the electric motor according to the invention do not always have to have the same number of magnets or magnetic poles. However, complementary rotor magnet assemblies and adjusting magnet assemblies preferably correspond to each other in the number of their magnets or magnetic poles and / or their other configuration. In particular, an at least substantially identical or symmetrical configuration of the complementary rotor magnet assemblies and adjusting magnet assemblies of a pair is preferred.

[0033] With regard to minimizing design complexity, permanent magnets are particularly suitable for use in rotor magnet devices and / or adjustment magnet devices. Besides cost-effective iron magnets, neodymium magnets are especially preferred, as they are characterized by high remanence and are therefore particularly suitable for compact designs of rotor and adjustment magnet devices. Alternatively or additionally to permanent magnets, an adjustment magnet device can also incorporate an electromagnet. This allows not only the relative position of the adjustment magnet device to a complementary adjustment magnet device of the other rotor to be adjusted, but also the field strength and thus the corrective force.

[0034] Furthermore, the electromagnet design allows the adjusting magnet device to be switched on and off as needed. For example, in conjunction with electronic control of the electric motor, particularly with regard to speed, the electromagnetic effect of the adjusting magnet device can be activated to correct any fluctuations in speed or asynchrony. In particular, the occurrence of superimposed torsional vibration can thus be suppressed at an early stage, preferably before the vibration amplitude reaches a critical level that would disrupt proper operation.

[0035] With regard to the rotational movement, at least one of the adjusting magnet devices has a cylindrical base. The longitudinal axis of the cylinder runs parallel to the axis of rotation of the rotor shaft and preferably coincides with it. The magnetic poles of the adjusting magnet device can preferably be arranged equidistantly around the cylinder.

[0036] Alternatively or additionally, at least one of the adjusting magnet devices can deviate from a purely cylindrical shape, particularly by having a radially projecting, preferably ring-shaped, element or several such elements, preferably spaced axially apart. In principle, this allows the magnets or the position of the magnetic poles to be displaced radially further outwards, thus reducing the distance between the adjusting magnet devices of the two rotors without increasing the overall diameter of the adjusting magnet device, i.e., over its entire axial length. In this way, the moment of inertia of the adjusting device is kept comparatively low despite the outward displacement of the magnetic poles, and the risk of disruptive imbalances is reduced. This results in smoother rotor operation and improved controllability of the rotational movement.

[0037] A particularly preferred embodiment of the invention provides that two complementary adjusting magnet devices each have at least one radially projecting element, in particular an axial section, which projects at least partially radially from the respective shaft to such an extent that the corresponding areas of the complementary adjusting devices overlap at least partially in axial projection. This can be achieved, for example, by one or more disk-like structures of an adjusting magnet device, each of which engages in corresponding free spaces, preferably annular grooves, of the respective complementary adjusting magnet device. If the magnetic poles of the adjusting magnet devices are arranged radially outward in the corresponding areas, i.e., in particular in the disk-like structures, this results in a spatial interlocking of the magnetic poles of the complementary adjusting magnet devices with one another.In this case, the magnetic interaction no longer occurs solely via the opposing tangential surfaces of the adjusting magnet devices. Rather, the interlocked arrangement allows the magnetic poles to be introduced further into the field of their respective corresponding magnetic poles of the complementary adjusting magnet device. This strengthens the magnetic coupling between the adjusting magnet devices, and thus, in particular, the maximum achievable correction force. In the case of multiple, especially axially offset, radially projecting elements—for example, in the form of several parallel disk-like structures—a magnetic pole of one adjusting magnet device preferably penetrates the designated free space of the complementary adjusting magnet device in such a way that the magnetic field of two or more of the magnetic poles adjacent to the free space acts upon it, thereby further strengthening the coupling.

[0038] A higher degree of integration can be achieved by integrating at least one of the adjusting magnet devices, at least substantially, into the associated shaft. In this case, no or only minimal portions of the adjusting magnet device protrude beyond the mean radius of the shaft. This is particularly advantageous when the shafts are arranged close together. Especially in this case, but also independently of this, a corresponding integration of at least one rotor magnet device is also preferred. Integration of both an adjusting magnet device and a rotor magnet device need not be on the same shaft, but can also be provided on different shafts.

[0039] Another approach to compensating for errors in the coupling of the rotors via the rotor magnet devices can be achieved by making at least one of the adjusting magnet devices axially displaceable along its associated shaft. This allows, for example, a response to locally occurring imbalances in the axial direction or torsion of the rotor or shaft that occurs temporarily and / or periodically.

[0040] Alternatively or additionally, at least one of the rotor magnet devices arranged in the stator can be arranged to be axially displaceable and / or offset relative to the complementary rotor magnet device.

[0041] According to the invention, it is not strictly necessary for an adjusting magnet device to have only one group of magnets at a specific axial position, for example, in the form of a ring of magnets or magnetic poles arranged around the shaft. In a preferred embodiment, a plurality of axially offset magnets and / or magnetic groups associated with an adjusting magnet device can also be provided. Such an adjusting magnet device can thus also have a plurality of ring-shaped magnetic groups, wherein the various magnets or magnetic groups can be arranged both directly adjacent to one another and spaced apart from one another in the axial direction. Furthermore, different magnetic groups of an adjusting magnet device can also have different numbers of magnetic poles.Furthermore, the magnet groups are preferably adjustable independently of each other by adjusting their rotational angle relative to the complementary adjusting magnet device of the other shaft.

[0042] Smooth rotor operation is achieved through continuous magnetic interaction, particularly between two complementary adjusting magnet devices. In an adjusting magnet device with axially offset magnets, these magnets are rotated relative to each other around the shaft axis. A spiral or helical arrangement of identical magnetic poles around the shaft axis is particularly preferred. During rotor rotation, two magnetic poles of the complementary adjusting magnet devices initially interact with each other. As the rotation continues, these magnetic poles move away from each other, while the axially adjacent magnetic poles interact more strongly with each other.Due to the helical arrangement of the identical magnetic poles around the shaft axis, this sequence continues in the axial direction as the rotors rotate and begins again after a complete rotation.

[0043] A rotational adjustment of the adjusting magnet assembly relative to its associated shaft by a specific angle, to compensate for the disruptive effects described above, affects all magnetic poles equally, even in a helical arrangement. However, this avoids the periodic occurrence of peak values ​​in the corrective force acting between the adjusting magnet assemblies. The corrective force reaches its maximum when two complementary magnetic poles of the adjusting magnet assemblies reach their smallest distance from each other as a result of the rotation. If the rotation continues, the corrective force initially decreases again until the next pair of magnetic poles interacts. The periodic action of these force peaks can cause undesirable vibrations, leading to uneven rotor operation.A nearly continuous distribution of the corrective force acting between the magnetic poles of two complementary adjusting magnet devices over a part of the circumference of the adjusting magnet device, preferably over its entire circumference, can significantly reduce the aforementioned effect.

[0044] A helical arrangement of the magnetic poles is particularly preferred, in which the interaction of the first magnetic poles at one axial end of the adjusting magnet assembly connects as seamlessly as possible to the interaction of the last magnetic poles at the other axial end of the adjusting magnet assembly. For this purpose, the helix described by the magnetic poles preferably completes one full revolution or an integer number of revolutions around the rotor. In this case, the first and last pairs of magnetic poles of the adjusting magnet assembly behave as if they were directly adjacent and continued the helix. Thus, during rotation of the rotors, there is no significant interruption in the mutual coupling or in the effect of the corrective force between the adjusting magnet assemblies.

[0045] One or more of the adjusting magnet devices can be connected to the shaft by a suitable support device. For this purpose, the support device, which is preferably a sleeve made of aluminum, is arranged appropriately on the shaft. If an adjusting device is first manufactured on a support device and then slid onto the respective shaft or otherwise attached using this device, this significantly simplifies the overall design of the rotor or electric motor. In addition to cost-effective manufacturing, this also facilitates easier maintenance and repair. For these purposes, the adjusting magnet device can be easily removed from the shaft and repaired or replaced outside the electric motor.

[0046] A vacuum pump, which is driven by an electric motor according to the invention, also possesses its own inventive significance in the present case. The vacuum pump according to the invention is, in particular, a rotary lobe pump, a rolling piston or Roots pump, or a screw pump. Generally, the vacuum pump according to the invention has at least two displacement elements that are driven rotationally by the electric motor. However, the pump is not limited to a specific type of displacement element. A combination of different types of displacement elements, for example in the form of several downstream pump stages, is also possible.

[0047] The vacuum pump according to the invention is designed in particular for medium and low flow rates. Preferably, it has a pumping speed of less than 50 m³ / h.

[0048] In In a particular embodiment, at least one of the displacement elements has an additional rotor magnet device, so that magnetic coupling of the rotors also exists in the pumping chamber. Alternatively or additionally, the adjusting magnet device of the respective shaft or an additional adjusting magnet device on or in the displacement element of the shaft can be provided. This further reduces the degree of integration and thus the size of the pump. Furthermore, an additional coupling and / or adjustment option for compensating for misalignments of the rotational angle is implemented in the area of ​​the displacement elements where superimposed torsional vibrations or other fluctuations in speed or disturbances in the synchronous operation of both rotors have the most negative impact.

[0049] To detect the rotational position or rotational speed of a rotor, a corresponding detection device is preferably provided. In particular, the vacuum pump has a corresponding sensor circuit that interacts with a complementary encoder magnet of the rotor. In a particularly preferred embodiment, at least one of the adjustment magnet devices of a rotor comprises a magnet that fulfills the function of an encoder magnet in such an arrangement.

[0050] The invention is explained in more detail below with reference to exemplary embodiments. All features described and / or illustrated in the drawings constitute independent aspects of the invention, irrespective of their combination in the exemplary embodiments or the cross-references in the claims.

[0051] It shows. Fig. 1 a schematic sectional view of an electric motor according to the invention in the drive area, Fig. 2 one of the Fig. 1 corresponding representation of the electric motor of Fig. 1 in an alternative operating state, Fig. 3 a schematic longitudinal section of the electric motor according to the invention, Fig. 4A a cross-sectional view of two rotor magnet devices, Fig. 4B a cross-sectional view of two adjusting magnet devices, Fig. 5 a schematic top view of two rotors of a vacuum pump according to the invention, Fig. 6 a schematic longitudinal section of a vacuum pump according to the invention and Fig. 7 a schematic longitudinal section of a preferred embodiment of two adjusting magnet devices.

[0052] In Fig. 1 An electric motor 1 according to the invention with two shafts 2 is shown in a cross-sectional view. In this representation, the section plane runs perpendicular to the longitudinal or rotational axis of the shafts 2 in the area of ​​the actual electric motor drive, as shown in Fig. 3 The electric motor 1 is preferably designed as a two-shaft synchronous motor. The electric motor 1 is preferably designed as a two-shaft synchronous motor. The electric motor 1 is indicated by a dashed line I / II / IVA.

[0053] The shafts 2 run parallel and each carries a rotor magnet assembly 3, which is non-rotatably connected to the shaft 2. During operation of the electric motor 1, the rotor magnet assemblies 3 of both shafts serve to drive, in particular, counter-rotating movements of the shafts 2. In this case, they are arranged in a common stator 4, as shown in Fig. 1 und 2 shown. The stator 4 is designed to generate a magnetic field that interacts with the rotor magnet devices 3 and sets them into rotation in the sense of a drive when the stator field changes periodically accordingly.

[0054] In the operating state of the electric motor 1, both rotor magnet assemblies 3 are thus simultaneously affected by the magnetic field generated by the stator 4. This does not mean, however, that the shape of the magnetic field and / or the field strength must be identical at the locations of both rotor magnet assemblies 3. Rather, this can be configured differently depending on the application and the design. Nevertheless, when the stator 4 is switched on, i.e., in particular when it is electrically energized, both rotor magnet assemblies 3 experience the generated field simultaneously and synchronously with respect to any changes or fluctuations in the field. This ensures that no fluctuations in speed or differences in rotational speed of the two shafts 2 are to be expected.

[0055] The stator 4 has an interior space 5 in which the rotor magnet devices 3 are arranged. The magnetic field of the stator 4 is generated in the interior space 5 by means of a field generator 6, preferably by means of a plurality of field generators 6. The field generators 6 are, in particular, coils that generate a magnetic field when an electric current flows through them. The shape and local field strength of the magnetic field in the interior space 5 can be influenced by the number and arrangement of the field generators 6.

[0056] The stator interior 5 is formed, in particular, within a housing 7. The housing 7 can extend right up to the stator interior 5. However, an embodiment is also possible in which the housing 7 merely forms an outer enclosure for the moving and electrically conductive components and thus serves to protect a user. The stator interior 5 is ultimately formed by the arrangement of the field generators 6 and its shape is significantly influenced by this arrangement. Functionally, the stator interior 5 is the area surrounded by the field generators 6 in which the magnetic field for driving the rotor magnet devices 3 is generated. A cutout in the housing 7 adapted as precisely as possible to this area, as shown in the Fig. 1 und 2 However, as depicted, it can be advantageous with regard to thermal and / or electromagnetic shielding or noise reduction.

[0057] During operation of the electric motor 1, the rotor magnet devices 3 are set into rotation by a changing magnetic field of the stator 4. As previously described, the field of the stator 4 is generated in particular by field generators 6. If coils used as field generators 6 are constantly energized by a constant direct current, a static magnetic field is created in the stator interior 5, according to which the rotor magnet devices 3 align themselves with respect to their rotational position.

[0058] The rotor magnet assembly 3 comprises at least one magnet for interacting with the field of the stator 4. Accordingly, the rotor magnet assembly 3 each has at least two magnetic poles 8 – a magnetic north pole N and a magnetic south pole S. If an external field of sufficient strength is applied in the region of the rotor magnet assembly 3, the magnetic poles 8 align themselves with this field, causing the rotor magnet assembly 3 to rotate together with the shaft 2. A periodic change in the external field causes a further alignment of the magnetic poles 8, so that the rotational motion continues and can be maintained continuously.

[0059] In the absence of an external field, particularly the stator field, the interaction of the magnetic poles 8 of the two adjacent rotor magnet assemblies 3 becomes apparent. The rotor magnet assemblies 3 align themselves with respect to their rotational angle such that two different magnetic poles 8 of the two rotor magnet assemblies 3 face each other and are spaced as close together as possible, as shown in the illustration of Fig. 1 . This interaction results in a coupling effect between the rotor magnet devices 3 in the sense of a magnetic transmission.

[0060] In the presence of the magnetic field generated by the stator 4, both of the aforementioned interactions—i.e., the reaction of the magnets or magnetic poles 8 to the external field and the mutual coupling of the magnetic poles 8 of the complementary rotor magnet assemblies 3 to each other—occur simultaneously and in a competing manner. With a view to trouble-free operation, the manufacturing of the electric motor 1 generally aims to ensure that the alignment of the rotor magnet assemblies 3 with respect to the field of the stator 4 and with respect to the field of the magnetic poles 8 of the respective complementary rotor magnet assemblies 3 corresponds as closely as possible. In this case, even with an activated (static) stator field, the alignment of the rotor magnet assemblies 3 according to Fig. 1 to be expected.

[0061] However, due to manufacturing tolerances and the limited assembly accuracy in practice, the following often occurs: Fig. 2 The case shown occurs when a constant magnetic field is generated by the stator 4, for example by supplying it with a time-invariant direct current. Since the external field generated by the stator 4 is generally greater in magnitude than the coupling between the magnetic poles 8 of the rotor magnet assemblies 3, these primarily align themselves with the external field. If the respective rest positions of the rotor magnet assemblies 3 deviate from each other due to manufacturing processes, both with respect to the external field and with respect to the field of the other rotor magnet assembly 3, the Fig. 2 The case shown illustrates this. Here, the rotor magnet devices 3 assume a position that largely corresponds to the rest position with respect to the stronger magnetic field of the stator 4. However, this position represents a deflection from the rest position with respect to the mutual magnetic interaction of the rotor magnet devices 3. This imbalance persists even during the rotation of the rotor magnet devices 3 in a dynamically changing stator field, particularly when the field generators 6 are energized in a periodically changing manner.

[0062] The previously described deflection of the rotor magnet assemblies 3 from their rest position with respect to their mutual coupling results in a tension in the form of a resulting relative force, corresponding to the spring tension of a deflected mechanical spring. This force generates a relative torque between the rotor magnet assemblies 3 and the shafts 2. This can become problematic, particularly at high speeds of the electric motor 1, because the tension between the rotor magnet assemblies 3 and the shafts 2 creates an oscillating system. During operation of the electric motor 1, this can lead to a superimposed torsional vibration of the rotor magnet assemblies 3 and the shafts 2 relative to each other. As the amplitude of this superimposed torsional vibration increases, the coupling of the rotor magnet assemblies 3, and thus the synchronicity of the rotational motion of both shafts 2, deviates further and further from the desired range.This is particularly critical if the oscillating system or the superimposed torsional vibration reaches resonance at a specific rotational speed. In such a case, the resulting increase in the vibration amplitude can lead to a collision of components driven by the electric motor 1, or even their destruction.

[0063] The invention is based on the provision of at least one adjusting magnet device 9 on each of the two shafts 2. Preferably, two adjusting magnet devices 9 form a complementary pair.

[0064] The adjusting magnet devices 9 are arranged on the shaft 2 in addition to the rotor magnet devices 3, as shown in Fig. 3 This is illustrated by way of example. At least one of the adjusting magnet devices 9 is arranged, in particular, outside the stator 4. In the illustration of Fig. 3 This is visually illustrated by limiting the housing 7 in the axial direction to the area of ​​the rotor magnet devices 3. It is understood that the housing 7 can also enclose the adjusting magnet devices 9 as well as other parts of the electric motor 1.

[0065] The function of the adjusting magnet devices 9 is based on the fact that at least one of the adjusting magnet devices 9 can be adjusted by means of rotation relative to the associated shaft 2, or its angular position relative to the complementary adjusting magnet device 9 of the other shaft 2 can be changed. For this purpose, the adjusting magnet device 9 is attached to the shaft 2 in such a way that it rotates with the shaft 2, but its angular position relative to the shaft 2, and thus relative to the complementary adjusting magnet device 9 of the other shaft 2, can be changed and fixed in this changed position.

[0066] The representations of Fig. 4A und 4B The relative orientations of the rotor magnet devices 3 and the adjusting magnet devices 9 to each other are illustrated. This corresponds to... Fig. 4A the section through the rotor magnet devices 3 according to the in Fig. 2 The situation shown, but without the surrounding components of the stator 4 and the housing 7, is as follows. It is evident that the magnetic poles 8 of the two rotor magnet assemblies 3, which are closest to each other, are not in a position corresponding to their rest position due to their mutual attraction. In this rest position, the magnetic north pole N of the rotor magnet assembly 3 on the left, which is closest to the rotor magnet assembly 3 on the right, would be oriented as the reference magnet or reference magnet pole such that its center point represents the point closest to the right rotor magnet assembly 3. In this example, the aforementioned center point of the magnetic north pole N is geometrically related to the circumferential direction. Functionally, this is, in particular, the point at which the magnetic field lines emerge perpendicularly and / or with the highest density.The same applies accordingly to the magnetic south pole S of the other rotor magnet assembly 3. The rest position would ultimately correspond to that in . Fig. 1 shown alignment of the rotor magnet devices 3.

[0067] The in Fig. 4A The case of tension between the rotor magnet devices 3 shown, including its negative consequences described above, can be compensated for or at least reduced to an acceptable level by the adjusting magnet devices 9 provided according to the invention. A section through the Fig. 3 The illustrated adjusting magnet devices 9 according to the section plane IVB are in Fig. 4B shown. Compared to Fig. 4A It can be seen that the adjusting magnet devices 9 are also rotated by a certain relative angle with respect to the position corresponding to the rest position based on the magnetic poles 8 of the adjusting magnet devices 9. A certain corrective force F1 now acts between the adjusting magnet devices 9 in addition to the coupling force F2, which acts between the rotor magnet devices 3.

[0068] In the statically considered case of the in Fig. 4A The tension shown between the rotor magnet devices 3 is caused by the correction force F1, which generates a relative torque between the adjusting magnet devices 9. This torque opposes the resulting relative torque caused by the coupling force F2 due to the deflection of the rotor magnet devices 3 from their rest position. According to the illustration of Fig. 3 The rotor magnet devices 3 and the adjusting magnet devices 9 of a common shaft 2 are rotationally coupled to each other via the shaft itself. Ideally, the unwanted torque caused by the coupling force F2 and the counter-torque generated by the corrective force F1 via the adjusting magnet devices 9 largely cancel each other out with respect to the shaft 2.

[0069] The extent to which the in Fig. 4A The undesired tension between the rotor magnet devices 3 shown in the diagram cannot usually be predicted with sufficient accuracy. Therefore, the solution according to the invention allows the rotational angular position of the adjusting magnet devices 9 relative to each other to be adjusted in order to adapt the corrective force F1 or the resulting counter-torque to the specific application situation.

[0070] In the dynamic case, i.e., during the rotational movement of the shafts 2 while the electric motor 1 is operating, the superimposed torsional vibration described above can occur. If the amplitude, i.e., the relative rotation angle of the rotor magnet assemblies 3, increases as the torsional vibration builds up, the adjusting magnet assemblies 9 are also rotated more strongly relative to each other due to their coupling with the respective rotor magnet assemblies 3. Depending on the setting of the fundamental relative alignment of the complementary adjusting magnet assemblies 9, the corrective force F1, in the case of high amplitudes, causes a correspondingly increased torque between the shafts 2, acting in the opposite direction to the vibration, thereby damping the disruptive torsional vibration and bringing it to a standstill.

[0071] In the process described above, it is advantageous if the correction force F1 is greater than or at least equal to the coupling force F2. This is particularly relevant when comparing two pairs of complementary rotor magnet devices 3 and adjustment magnet devices 9. Alternatively or additionally, this condition can also apply to the sum of all occurring correction forces F1 and the sum of all occurring coupling forces F2 combined (if multiple adjustment magnet devices 9 and / or rotor magnet devices 3 are used).

[0072] Based on the comparison of Fig. 4A und 4B It becomes apparent that the rotor magnet devices 3 and the adjusting magnet devices 9 do not necessarily have to have the same number of magnetic poles 8. Rather, the respective number depends on how finely tuned the coupling between the rotor magnet devices 3 or the adjustability of the corrective effect of the adjusting magnet devices 9 is required in the specific application.

[0073] The rotor magnet devices 3 and / or the adjusting magnet devices 9 each comprise at least one magnet from which the magnetic poles 8 are provided. The magnet is preferably sintered and / or can be attached to the shaft 2 or a separate support device of the rotor magnet device 3 or adjusting magnet device 9 (not shown in detail for clarity) by gluing, pressing, shrinking, or other means that are materially, force-, and / or form-fit.

[0074] Particularly preferably, a rotor magnet assembly 3 and / or an adjustment magnet assembly 9 of the electric motor 1 according to the invention has a magnetic multipole. For the sake of simplicity, a magnetic quadrupole is shown here ( Fig. 1, 2 , 4A ) or an eightfold multipole ( Fig. 4B ) selected. In principle, however, it can be an n-fold multipole, i.e., a higher-order multipole, in which, according to the invention, there is no fundamental upper limit for the number of magnetic poles 8. An eight-fold multipole, more preferably a twelve-fold multipole, and most preferably a twenty-four-fold multipole, has proven to be a particularly suitable compromise between the required design effort and good functional performance. The aforementioned values ​​correspond in particular to lower limits for the preferred number of poles of the multipole.

[0075] The magnets of the rotor magnet devices 3 and / or the adjustment magnet devices 9 are, in particular, permanent magnets that generate a magnetic field independently of an external power supply and thus exert a coupling or corrective effect. In a preferred embodiment, however, the magnets of at least one rotor magnet device 3 and / or one adjustment magnet device 9 are designed as electromagnets, preferably having one or more contact brushes. Alternatively or additionally, such an electromagnet can also be designed for contactless operation, in particular by means of induction. Furthermore, induced eddy currents can also contribute to counteracting speed fluctuations. Thus, the strength of the corrective force F1 and / or the coupling force F2 can be influenced, in particular continuously, and / or the associated effect can be switched on and off as needed.It is understood that permanent magnets and electromagnets can also be provided in combination on a rotor magnet device 3 or adjustment magnet device 9 or on different rotor / adjustment magnet devices 3, 9.

[0076] A cylindrical shape is particularly advantageous for the adjusting magnet devices 9, but also for the rotor magnet devices 3, with regard to the rotational movement they perform during the operation of the electric motor 1. Accordingly, an adjusting magnet device 9 and / or a rotor magnet device 3 can have a cylindrical base. The axis of rotational symmetry of the cylinder is, in particular, parallel to, or coincides with, the longitudinal and rotational axis of the shaft 2, as shown in Fig. 3 depicted.

[0077] A generally cylindrical basic shape of the base body of the adjusting magnet devices 9 or rotor magnet devices 3 does not preclude the possibility of one or more elements projecting radially from a cylindrical basic shape, particularly in the form of disk-like structures. In this case, an overall rotationally symmetrical design with respect to the cross-section perpendicular to the axis of rotation is advantageous. Fig. 7 Figure 1 shows an exemplary embodiment of the adjusting magnet devices. In this case, the magnetic poles 8 are located in the radially outer region of the projecting elements.

[0078] By forming disk-like structures with intervening free spaces, in this case in the form of circumferential ring grooves, a spatial entanglement of the mutually assigned magnetic poles 8 is possible without the risk of a mechanical collision of components, even in the case of strong fluctuations in speed.

[0079] In In the preferred embodiment shown, a magnetic north pole N of one adjusting magnet assembly 9 is located between two magnetic south poles S of the complementary adjusting magnet assembly 9, and vice versa. The adjusting magnet assemblies 9 are thus more strongly coupled to each other than in the case of a merely opposite arrangement of the magnetic poles 8, i.e., without the entanglement shown here. This allows a greater corrective force to be exerted in the case of wow and flutter fluctuations between the shafts 2. As a result of the rotation of the adjusting magnet assemblies 9, the magnetic north poles N and south poles S alternately move to the position closest to each other, so that the Fig. 7 The relationship between the North Pole (N) and the South Pole (S) shown is periodically reversed.

[0080] It is understood that, contrary to the representation according to Fig. 7 An irregular or asymmetrical arrangement of projecting elements and corresponding clearances may also be provided. Furthermore, one or both adjusting magnet devices 9 may also have several separate, axially spaced disks, rings, or the like, which interact with each other in the manner described above.

[0081] Conversely, an adjustment magnet device 9 and / or a rotor magnet device 3 can alternatively or additionally be integrated into the shaft 2 to achieve the most compact design possible. For this purpose, the shaft 2 can have a correspondingly reduced diameter in the area of ​​the respective adjustment magnet device 9 or rotor magnet device 3, so that, as a result, no components of the adjustment magnet device 9 or rotor magnet device 3 protrude beyond the maximum radius of the shaft 2 in the relevant area.

[0082] Furthermore, it is by no means necessary that the adjusting magnetic devices 9 be in the Fig. 3 The adjusting magnets 9 are arranged close to the rotor magnet devices 3 as shown. A corresponding spacing along the axis of the shaft 2 is also possible according to the invention. In a particularly preferred embodiment, at least one of the adjusting magnet devices 9 can even be designed to be displaceable in the axial direction, i.e., along the shaft 2.

[0083] The sectional views of the Fig. 1, 2 , 4A und 4B This might suggest that the rotor magnet devices 3 or adjusting magnet devices 9 may have a plurality of magnets or magnetic poles 8 along their circumference, but have a constant structure in the axial direction. However, according to the invention, a design is also possible in which several magnets, in particular of different configurations, are provided in an adjusting magnet device 9. This can, in particular, be a sequence of magnets preferably arranged in a ring around the shaft 2, wherein the number of magnetic poles 8 of each ring can be different.

[0084] Furthermore, it is also possible to arrange not only magnets that are directly adjacent in the axial direction, but also to establish a spacing between axially offset magnets or, in particular, ring-shaped groups of magnets. This allows for consideration of structural conditions depending on the specific application.

[0085] Axially offset magnets can also be offset by different rotation angles. In particular, an inclined toothing of the magnets or magnetic poles 8 is possible, preferably in the form of a helical arrangement of the magnetic poles 8 around the shaft 2, resulting in an almost continuous effect of the correction force F1 with greater smoothness of operation.

[0086] Furthermore, by means of several axially offset and independently adjustable magnets or magnet groups of an adjusting magnet device 9, as well as by means of a plurality of adjusting magnet devices 9 on a shaft 2, it is also possible to react to disturbing phenomena other than pure torsional vibration. These include, for example, a superimposed bending vibration or a torsional vibration of the shaft 2.

[0087] The support device for magnets of the adjusting magnet assembly 9 or the rotor magnet assembly 3, and / or for the adjusting magnet assembly 9 or the rotor magnet assembly 3 itself, which is not shown in detail for the sake of simplicity, is designed in particular as a sleeve. Preferably, an aluminum sleeve is used. A particularly preferred embodiment is one in which a support device is provided that carries at least one of the adjusting magnet assemblies 9 as a whole, so that it can first be manufactured completely and then mounted onto the shaft 2 by means of the support device. In particular, one or more magnets, preferably in the form of bar magnets, can be inserted into the sleeve.

[0088] A support structure, particularly a sleeve-like one, can also serve as a heat sink to cool the magnets. Otherwise, in the case of permanent magnets, there is a risk of thermal demagnetization if the temperature rises too much during operation.

[0089] The electric motor 1 according to the invention is particularly suitable for driving a vacuum pump 10, such as those used in Fig. 6 This is illustrated by way of example. In such a vacuum pump 10, the electric motor 1, in particular as a two-shaft synchronous motor, serves to drive two rotors 11 which are in Fig. 5 The following are shown in a schematic top view. A rotor 11 of the vacuum pump 10 comprises, in addition to the shaft 2, at least one rotor magnet assembly 3, and an adjusting magnet assembly 9, in particular one or more displacement elements 12. In the example shown here, the displacement element 12 is designed as a screw for a screw pump. An exemplary non-compressive embodiment is shown, in which the screw has a constant pitch. It is understood that an embodiment with a variable pitch, particularly for compression, can also be provided. Furthermore, displacement elements 12 in the form of rotary or rolling pistons, or displacement elements 12 based on a comparable principle, are also possible.

[0090] According to the schematic exemplary representation of Fig. 6 In the vacuum pump 10 according to the invention, it is particularly provided that the two rotors 11 are driven by means of the electric motor 1 according to the invention. The previously described function of the adjusting magnet devices 9 is used here. In the case of the vacuum pump 10 shown here, the parallel rotors 11 run, on the one hand, in the area of ​​the drive-effective part of the electric motor 1, i.e., in particular in the stator 4, and / or a housing 7 of the electric motor 1.

[0091] Furthermore, the shafts 2 of the rotors 11 are extended such that they pass through a pump housing 13 and are rotatably mounted there. The displacement elements 12 are arranged in the front part of the pump housing 13. They interact in such a way that a pumped medium, for example, a fluid to be evacuated from an enclosed space, preferably a gas, is drawn into the pump housing 13 via a suction port 14 and transported further by the displacement elements 12. In the pumping direction beyond the displacement elements 12, the transported medium then leaves the pump housing 13 through an outlet port. In the example shown here, this outlet port is arranged perpendicular to the plane of the image and is therefore not shown in the present sectional view.

[0092] The displacement elements 12 preferably do not touch each other or the pump housing 13 during operation. Nevertheless, sufficient sealing between the displacement elements 12 and the pump housing 13 must be ensured. Therefore, extremely small gaps between the components involved are used. The problems described above, such as speed fluctuations, synchronization errors between the rotors 11, and especially the accumulation of superimposed torsional vibrations of the rotors 11, can thus quickly become critical for the operation of the vacuum pump 10.

[0093] In a particularly preferred embodiment, at least one of the displacement elements 12 can have an additional rotor magnet assembly 3. This allows the coupling between the two rotors 11 to be strengthened if the complementary displacement elements 12 additionally form a further magnetic transmission by means of corresponding rotor magnet assemblies 3.

[0094] Alternatively or additionally, a preferred embodiment may provide that one or more adjusting magnet devices 9 are integrated into the displacement elements 12. These may be one of the primary adjusting magnet devices 9 or an additional adjusting magnet device 9. The corrective effect of the adjusting magnet device 9 can thus act directly where negative consequences would first become apparent in the event of a malfunction of the aforementioned kind.

[0095] The electric motor 1 or the vacuum pump 10 may also have a control unit 15, in particular an electronic one, by means of which, for example, the rotational speed of the rotors 11, the strength and / or phase of the stator field, the flow rate of the vacuum pump 10, the noise level in the vicinity of the vacuum pump 10, the power consumption of the electric motor 1 and / or a temperature value can be recorded or monitored. Furthermore, it is also possible to regulate the aforementioned and / or other parameters by means of the control unit 15.

[0096] A suitable device can be provided to detect the rotational speed and / or the rotational position of one or both rotors 11. For this purpose, the vacuum pump 10 preferably has a corresponding sensor circuit, which is particularly integrated into the control unit 15. A sensor magnet can be read by means of the sensor circuit, which indicates to the sensor circuit or the control unit 15 a complete or partial rotation of the rotor. A corresponding sensor magnet is preferably integrated into at least one of the adjusting magnet devices 9, so that no additional component for monitoring the rotational movement needs to be added to the rotor 11. Particularly preferably, a magnet or a magnetic pole 8 of the adjusting magnet device 9 is perceived by the complementary sensor circuit as the sensor magnet. Bezugszeichenliste:

[0097] 1 Electric motor 2 Shaft 3 Rotor magnet assembly 4 Stator 5 Stator interior 6 Field generator 7 Housing 8 Magnetic pole 9 Adjustment magnet assembly 10 Vacuum pump 11 Rotor 12 Displacement element 13 Pump housing 14 Suction port 15 Control N magnetic north pole S magnetic south pole

Claims

1. Electric motor (1), in particular a two-shaft synchronous motor, preferably for operating a vacuum pump (10), with two rotor magnet devices (3) each arranged on parallel shafts (2), wherein, in the operating state of the electric motor (1), the rotor magnet devices (3) are arranged in a common stator (4) in such a way that they interact with each other for mutual coupling with regard to their rotational angular position, wherein, in addition to the rotor magnet devices (3), at least one adjusting magnet device (9) is arranged on each of the two shafts (2), characterized in that at least one of the adjusting magnet devices (9) can be adjusted by means of rotation relative to the associated shaft (2) and / or can be changed in the rotational angular position relative to a complementary adjusting magnet device (9) of the respective other shaft (2).

2. Electric motor according to claim 1, characterized in that at least one of the adjusting magnet devices (9) of each shaft (2) is arranged outside the stator (4).

3. Electric motor according to claim 1 or 2, characterized in that there is a correction force (F1) between the complementary adjusting magnet devices (9) which is greater than or equal in amount to a coupling force (F2) acting between two complementary rotor magnet devices (3).

4. Electric motor according to one of the preceding claims, characterized in that at least one of the rotor magnet devices (3) and / or at least one of the adjusting magnet devices (9) has one or more magnets, in particular sintered and / or bonded and / or pressed magnets.

5. Electric motor according to one of the preceding claims, characterized in that at least one of the rotor magnet devices (3) and / or at least one of the adjusting magnet devices (9) has a magnetic multipole, preferably an at least eightfold multipole, more preferably an at least 12-fold multipole, particularly preferably an at least 24-fold multipole.

6. Electric motor according to one of the preceding claims, characterized in that at least one of the adjusting magnet devices (9) comprises an electromagnet.

7. Electric motor according to one of the preceding claims, characterized in that at least one of the adjusting magnet devices (9) has a cylindrical base body and / or that at least one of the adjusting magnet devices (9) has one or more radially protruding elements.

8. Electric motor according to one of the preceding claims, characterized in that at least one of the adjusting magnet devices (9) is integrated into the shaft (2).

9. Electric motor according to one of the preceding claims, characterized in that at least one of the adjusting magnet devices (9) is axially displaceable along the shaft (2).

10. Electric motor according to one of the preceding claims, characterized in that at least one of the adjusting magnet devices (9) comprises a plurality of magnets arranged in an axially offset manner.

11. Electric motor according to claim 10, characterized in that the magnets of the adjusting magnet device (9) are rotated relative to each other about the shaft axis, in particular in such a way that a helical arrangement of identical magnetic poles (8) around the shaft axis results.

12. Electric motor according to one of the preceding claims, characterized in that a support device, in particular a sleeve, preferably an aluminum sleeve, for supporting at least one of the adjusting magnet devices (9) is arranged on the shaft (2).

13. Vacuum pump, in particular a rotary vane pump or screw pump, preferably with a pumping speed below 50 m3 / h, with at least one electric motor (1) for rotating at least two displacement elements (12), characterized in that the electric motor (1) is designed according to one of the preceding claims.

14. Vacuum pump according to claim 13, characterized in that at least one of the displacement elements (12) has an additional rotor magnet device (3) and / or one of the adjusting magnet devices (9) or an additional adjusting magnet device (9).

15. Vacuum pump according to claim 13 or 14, characterized in that at least one of the adjusting magnet devices (9) comprises a magnet which is designed as a transmitter magnet for interaction with a complementary sensor circuit.