Electric motors and vacuum pumps

Abstract

The present invention relates to an electric motor, in particular for a vacuum pump, with two magnetically coupled shafts. The proposed invention allows for the use of an adjusting magnet device to set a corrective force on each shaft, thereby compensating for the adverse effects caused by magnetic coupling inaccuracies.

Description

[Technical Field]

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

[0002] An example of an electric motor frequently used in industry is a multi-shaft electric motor, used to synchronously drive multiple shafts. Typical applications for electric motors with two shafts are pumps in which two displacement elements rotating relative to each other achieve the pump's output. These include screw pumps, Roots pumps, and screw compressors, among others. In these pumps, the shafts run in opposite directions. The displacement elements, e.g., screw spindles, engage with each other as closely as possible during rotational movement. However, they must not actually contact each other during this process, as this would have adverse effects on operation in the form of wear, noise generation, and increased power consumption. Therefore, particularly in view of the often high rotational speeds of such pumps, it is important to ensure precise manufacturing and accurate balancing and alignment of the moving components. Due to the required closeness, the gap width in the area of ​​the displacement elements is extremely small. As a result, only small manufacturing tolerances are assumed, and there are high requirements for the synchronization of the rotational movement of both shafts. Summary of the Invention [Problem to be solved by the invention]

[0003] Various approaches for synchronizing two shafts are already known from the prior art. For example, the shafts can be mechanically coupled, for example using gears. In this case, it is often sufficient to drive only one shaft, while the other shaft is driven through a gearbox. However, a drawback here is that the mechanical contact of the components of the coupling element causes the problems mentioned above, namely wear, operating noise, and increased power consumption. In addition to the relatively large space requirements, this solution also often requires moderate lubrication, which in turn requires a reliable and at the same time durable seal for the pump chamber. Due to the considerable design effort, this approach is relatively costly.

[0004] An alternative is a purely electronic control of the speeds of the shafts and their relative phases. However, very precise control with low latency times is required here, especially for high speeds. Besides a correspondingly powerful electronic control system, the design effort is relatively high due to complex sensor equipment for both shafts.

[0005] The drawbacks of the above solutions are partially overcome by using a motor in which both shafts are placed in a common stator field. Here, the stator field acts simultaneously on the two rotor magnet devices, each connected to a shaft. This means that both rotor magnet devices are always equally subjected to any fluctuations in the stator field. This largely avoids corresponding synchronous fluctuations.

[0006] Coupling of the rotational movement of the shaft is further achieved by adjacent arrangement of rotor magnet devices, which in this connection form a magnetic transmission.

[0007] However, the problem here is that the two magnetic fields, i.e., the stator magnetic field and the magnetic field of the other rotor magnet device, basically act independently of each other on each rotor device. Due to practical limitations in the precision of adjustment, a situation may arise here in which, with regard to shaft alignment, the rest position relative to the static stator magnetic field does not strictly correspond to the rest position of the rotor magnet devices with respect to their magnetic interaction with each other. The magnetic field strength of the stator magnetic field is usually higher than the coupling effect of the rotor magnet devices with each other. Therefore, when the stator magnetic field is effective, the two shafts in the above case are always offset by a certain rotation angle with respect to their rest positions relative to each other.

[0008] Similar to a tensioned spring, a tensile force exists between the rotor-magnet device in the form of a force transmitted to the shaft as a relative torque. This remains even when the stator magnetic field changes, i.e., when the shaft is driven. When the pump is operated under these conditions, superimposed rotational vibrations can result from slight synchronous fluctuations, which can impair the synchronous rotation of the shaft, i.e., lead to significant disturbances. Such rotational vibrations occur in a problematic manner, especially in systems with relatively long and relatively small shafts or systems with single-sided bearings. Furthermore, plastics such as PEEK are frequently used for the manufacture of pump components due to their chemical resistance. However, compared to metallic materials, plastics generally have a lower density and higher elasticity, which favors the generation of vibrations within the material.

[0009] In the case of a common stator field, the rotation of the shafts cannot be individually electronically controlled, so alternative possibilities must be resorted to to counteract destructive rotational vibrations. For example, the amplitude of this rotational vibration can be limited by a mechanical emergency gear that normally operates without contact. In this case, the relative rotation of the shafts is stopped, for example, by contact between the meshing gears. However, this leads, on the one hand, to considerable noise generation and, on the other hand, to increased maintenance needs due to short-term gear wear.

[0010] Furthermore, damping rotational vibrations by shifting the resonant frequency would require, among other things, adjusting the mass of the components involved. However, this approach is not equally effective at all speeds. In addition, designs that are too light are associated with structural instability, while designs that are too heavy lead to an undesirable increase in energy requirements. [Means for solving the problem]

[0011] Against this background, the invention is based on the problem of providing an electric motor with two shafts, in which the rotation of the shafts is particularly reliably synchronized and in particular the above-mentioned problems are avoided.

[0012] The above-mentioned problem is solved by an electric motor having the features of claim 1 as well as by a vacuum pump having the features of claim 13.

[0013] At least one adjusting magnet device on each of the two shafts of the electric motor according to the present invention can be used to compensate for the magnetic pulling force in the form of a force acting between the rotor magnet devices of both shafts as described above. For this purpose, a counter torque is generated between the two shafts by magnetic interaction between an adjusting magnet device of one shaft and a complementary adjusting device of the respective other shaft. This counter torque preferably acts as a corrective measure in the sense that, when the stator magnetic field is active, at least essentially no force acts between the rotor magnet devices, which is based on a shift in the rotation angle relative to one another compared to their relative rest position.

[0014] The adjusting magnet device preferably has a structure similar to that of the rotor magnet device. For example, the adjusting magnet device comprises at least one magnet, the magnetic poles of which can interact with the magnetic poles of the magnet of the complementary adjusting magnet device. However, the number, arrangement and / or orientation of the magnets can be individually different. In particular, an annular, preferably equidistant arrangement of magnets or magnetic poles around the shaft has proven to be particularly suitable.

[0015] In terms of relative rotation, the torque induced by the angular displacement corresponds to a deflection that counters the spring force in a system capable of vibrating. If the resulting torque is nearly zero, the system is less susceptible to superimposed rotational vibrations, even at high speeds, which can build up to critical limits depending on resonance conditions. If the amplitude of such rotational vibrations becomes excessively large, the magnetic coupling between the rotor-magnet devices can become asynchronous, so that synchronous operation of both shafts is no longer guaranteed. In the case of a pump, for example, this can lead to collisions of rotating displacement elements, which can lead to increased wear and operating noise, as well as, in severe cases, pump failure.

[0016] When relative synchronous fluctuations occur between the shafts during operation, the adjustment magnet devices rotate relative to each other, which, according to the invention, causes an increase in the corrective force between the respective magnetic poles of the adjustment magnet devices, counteracting the formation of rotational vibrations without wear.

[0017] The group of all components that rotate together with the shaft during operation of the pump is collectively referred to in the context of the present invention as the "rotor". In addition to the shaft itself, this also includes, in particular, the rotor magnet device, the adjusting magnet device, any replacement elements, and / or other components associated with the shaft that are connected to the shaft or other parts of the rotor so as to rotate together with the electric motor during operation.

[0018] The degree to which the two rotors are pulled relative to each other, i.e., rotationally displaced, in relation to their mutual magnetic interaction essentially depends on unavoidable tolerances in the manufacture of the components and in the assembly of the electric motor. This dimension can therefore hardly be predicted accurately. For this reason, at least one of the adjustment magnet devices is rotatably mounted on the associated shaft so that it can be adjusted relative to the latter by rotation. Alternatively or additionally, the adjustability of the adjustment magnet device can be expressed by the fact that its rotational angular position is variable relative to the complementary adjustment magnet device of the respective other shaft. That is, the specific adjustment of the correction position of the adjustment magnet device can be performed depending on the individual case.

[0019] Although it is not absolutely necessary that both interacting adjustment magnet devices of a complementary pair be adjustable in the above-described manner, this is provided in a preferred embodiment. This makes it easier to set the correct compensation position of the adjustment magnet devices. Furthermore, handling of the devices can be supported if one of the adjustment magnet devices is difficult for the user to reach, for example due to structural conditions.

[0020] As in the case of the rotor magnet devices, the mutual influence of the adjusting magnet devices preferably also couples the rotor according to the magnetic gear principle: in addition to their balancing effect, for example to avoid superimposed rotational vibrations as described above, the adjusting magnet devices also contribute in this way to stable synchronization of the rotor.

[0021] In addition to the actual magnetically interacting components, i.e., one or more magnets, the adjustment magnet device may also comprise further elements that contribute to the adjustability, for example, fastening to a shaft, cohesion of the magnets, and / or adjustability, especially in the form of rotation and / or axial displacement. The same applies to rotor magnet devices.

[0022] The rotor of an electric motor according to the invention or the rotor of a pump having an electric motor according to the invention can also have, in addition to the rotor magnet device and the adjusting magnet device arranged as part of the drive in the stator magnetic field, a further rotor magnet device outside the stator that contributes to a further magnetic coupling of the rotor. The invention also allows for combined designs of adjustable adjusting magnet devices and fixed (rigid) rotor magnet devices. In this case, the parts that are adjustable by rotation relative to the shaft preferably perform the above-mentioned function of the adjusting magnet device, i.e., in particular, static and / or dynamic compensation of undesired relative torques of the rotors relative to each other, while the parts fixedly connected to the shaft simply contribute to reinforcing the relative coupling of the rotors.

[0023] It is understood that several adjusting magnet devices can also be provided per shaft. In particular, the adjusting magnet devices of the shafts can be designed differently, for example by comprising a different number of magnets. In this way, a more precise setting of the compensation force or torque can be achieved in some applications.

[0024] Preferably, at least one of the adjusting magnet devices of each shaft is located outside the stator, which means that it is not subjected to any additional forces from the stator magnetic field, and its balancing function can therefore be performed independently of other forces acting on the rotor.

[0025] Functionally, a distinction must be made between the corrective forces acting between the adjusting magnet devices and the coupling forces acting between two complementary rotor magnet devices. This distinction does not contradict the fact that coupling also occurs due to the interaction of complementary adjusting magnet devices. The corrective forces result in particular from the specific setting of the relative rotation angle between the adjusting magnet devices. When the rotor rotates during operation, the corrective forces between the two adjusting magnet devices are preferably out of phase with the coupling forces between the two rotor magnet devices. An application of the coupling forces leads, for example, to an acceleration of the rotor's rotational movement, which is limited by the phase-shifted corrective forces.

[0026] Coupling forces typically only serve to synchronize rotors. Corrective forces therefore have the specific function of compensating for errors in the height, alignment, and / or phase of the coupling forces. These errors can be considered to be both static and dynamic in nature. In the latter case, this compensation prevents, for example, the formation of superimposed rotational vibrations as described above.

[0027] In a preferred embodiment, the corrective force between the complementary adjusting magnet devices is greater than or equal to the coupling force acting between the two complementary rotor magnet devices. In this way, the compensating corrective force can have a particularly effective effect. In particular, when the maximum achievable corrective force is significantly greater than the coupling force, the relative synchronous fluctuations and superimposed rotational vibrations preferably decay quickly before the rotational vibrations increase significantly or before the relative rotational displacement between the rotors reaches a critical level.

[0028] In the simplest embodiment, the rotor magnet device and / or adjusting magnet device of the electric motor according to the invention have only one magnet. However, embodiments with several magnets are particularly preferred, as this ensures a reliable coupling of the rotor in the case of the rotor magnet device and a more precise adjustment in the case of the adjusting magnet device. One or more magnets can be attached or mounted, in particular glued, to the rotor magnet device or adjusting magnet device as a whole and / or can consist of individual parts in the sense of a multi-part embodiment. Thus, the production of the corresponding components is possible in a simple and inexpensive manner. Preferably, sintered magnets and / or plastic-bonded magnets are used.

[0029] At least one of the rotor magnet devices and / or at least one of the adjustment magnet devices comprises a magnetic multipole. Since each magnet itself already represents a dipole, the term magnetic multipole in this specification refers to an embodiment with at least one magnetic quadrupole, i.e., an embodiment with at least four magnetic poles. However, magnetic multipoles of higher orders are particularly recommended, preferably at least octopoles, more preferably at least 12-pole, and particularly preferably at least 24-pole. However, according to the invention, there is no upper limit to the number of magnetic poles. In principle, n-multipoles can be used, meaning multipoles of any order. Depending on the number of magnetic poles of the rotor magnet device or adjustment magnet device, a correspondingly more precise rotor coupling or finer adjustment of the adjustment magnet device can be achieved, thereby compensating for the above-mentioned distortions.

[0030] It is understood that the rotor magnet devices and / or adjusting magnet devices of an electric motor according to the invention do not always have to have the same number of magnets or magnetic poles. However, rotor magnet devices and / or adjusting magnet devices that are complementary to each other preferably correspond to each other in the number of their magnets or magnetic poles and / or in other designs. In particular, at least substantially identical or symmetrical designs for a pair of complementary rotor magnet devices or adjusting magnet devices are preferred.

[0031] Permanent magnets are particularly suitable for use in rotor magnet devices and / or adjustment magnet devices due to the low design effort required. In addition to inexpensive iron magnets, neodymium-containing magnets are particularly preferred, as they are characterized by high remanence and are therefore particularly suitable for small-scale designs of rotor magnet devices and / or adjustment magnet devices. Instead of or in addition to permanent magnets, adjustment magnet devices can have electromagnets, which not only allow the relative position of the adjustment magnet device and the complementary adjustment magnet device of the respective other rotor to be adjusted, but also allow the magnetic field strength and therefore the corrective force to be set.

[0032] Furthermore, the design of the electromagnet allows the adjusting magnet device to be switched on and off as required, if and when necessary. For example, in connection with the electronic control of an electric motor, if a synchronous fluctuation or asynchronism, particularly with regard to speed, is detected, corrective measures can be carried out by switching on the electromagnetic effect of the adjusting magnet device. Thus, the occurrence of superimposed rotational vibrations in particular can be limited at an early stage, preferably before the vibration amplitude reaches a critical level that would prevent proper operation.

[0033] For rotational movement, at least one of the adjusting magnet devices has a cylindrical base body, where the longitudinal axis of the cylinder extends in particular parallel to, and preferably coincides with, the rotation axis of the rotor shaft. The magnetic poles of the adjusting magnet device can preferably be arranged equidistantly around the cylindrical barrel.

[0034] Alternatively or additionally, at least one of the adjusting magnet devices can deviate from a purely cylindrical shape, in particular by having radially protruding, preferably annular, elements or several such elements, in particular spaced apart from one another in the axial direction. Thus, in principle, it is possible to shift the position of the magnets or magnetic poles further outward in the radial direction and reduce the distance between the adjusting magnet devices of the two rotors without increasing the diameter of the adjusting magnet device as a whole, i.e., over its entire axial length. In this way, despite the magnetic poles being moved further outward, the moment of inertia of the adjusting device remains relatively low, reducing the risk of disturbance imbalance. As a result, the rotor runs more smoothly and the rotational movement becomes easier to control.

[0035] A particularly preferred embodiment of the present invention provides that two complementary adjusting magnet devices each have at least one radially protruding element, in particular an axial section, which at least partially radially protrudes from the respective shaft to such an extent that corresponding areas of the complementary adjusting magnet devices at least partially overlap in axial projection. This can be achieved, for example, by one or more disk-shaped structures of the adjusting magnet devices, each of which engages in a corresponding free space, preferably an annular groove, of the respective complementary adjusting magnet device. If the magnetic poles of the adjusting magnet devices are arranged radially outside the corresponding areas, i.e., in particular within the disk-shaped structures, the magnetic poles of the complementary adjusting magnet devices will spatially intertwine with each other. In this case, magnetic interaction no longer occurs exclusively through the opposing tangential surfaces of the adjusting magnet devices. Instead, the interlocking arrangement can further bring the magnetic poles into the magnetic field of the magnetic poles assigned to each complementary adjusting magnet device. This strengthens the magnetic coupling between the adjusting magnet devices, i.e., in particular the maximum achievable correction force. In the case of some, in particular axially offset radially protruding elements, for example in the form of several parallel disk-shaped structures, the magnetic poles of the adjustment magnet device preferably penetrate into the free space provided in the complementary adjustment magnet device, so that the magnetic fields of two or more of the magnetic poles adjacent to the free space act in each case, thereby further strengthening the coupling.

[0036] A higher degree of integration can be achieved by at least substantially integrating at least one of the adjustment magnet devices into the associated shaft, in which case, in the area of ​​the adjustment magnet device, no part of the adjustment magnet device, or at least only a small part of it, protrudes beyond the central radius of the shaft. This is particularly advantageous when the shafts are arranged closely adjacent. In this case, particularly, but independently of this, a corresponding integration of at least one rotor magnet device is also preferred. The integration of both the adjustment magnet device and the rotor magnet device does not have to be provided on the same shaft, but can also be provided on different shafts.

[0037] A further starting point for influencing the compensation of errors in the rotor coupling through the rotor magnet devices can be created by at least one of the adjusting magnet devices being axially displaceable along the associated shaft. In this way, it is possible to react, for example, to local axial imbalances or temporary and / or periodic rotor or shaft twists. Alternatively or additionally, at least one of the rotor magnet devices arranged on the stator can also be axially displaceable and / or offset relative to the complementary rotor magnet device.

[0038] According to the present invention, it is not absolutely necessary that the adjustment magnet device have only one magnet group at a specific axial position, for example in the form of a ring of magnets or magnetic poles arranged around the shaft. Rather, in preferred embodiments, there can be multiple axially offset magnets and / or magnet groups associated with the adjustment magnet device. Accordingly, such an adjustment magnet device can have multiple magnet groups arranged in a ring, where the various magnets or magnet groups can be both directly adjacent to each other in the axial direction and spaced apart from each other. Furthermore, different magnet groups of an adjustment magnet device can have different numbers of magnetic poles. Furthermore, the magnet groups are preferably adjustable independently of each other by adjusting their rotational angular positions relative to the complementary adjustment magnet device of the other shaft.

[0039] Smooth rotor operation is achieved in particular by continuous magnetic interaction between two complementary adjusting magnet devices. For this purpose, adjusting magnet devices with axially offset magnets rotate relative to one another around the shaft axis. In this case, a spiral or helical arrangement of identical magnetic poles around the shaft axis is particularly preferred. As the rotor rotates, the two magnetic poles of the mutually complementary adjusting magnet devices initially interact with one another. As the rotation continues, these magnetic poles move away from one another again, while axially adjacent magnetic poles interact more strongly. Due to the helical arrangement of identical magnetic poles around the shaft axis, this sequence continues axially as the rotor rotates and begins again after a complete rotation.

[0040] To compensate for the disturbance effects mentioned at the beginning, rotating the adjusting magnet devices by a certain rotation angle relative to the associated shaft also has the same effect on all magnetic poles in the spiral arrangement. However, in this way, periodic peaks of the corrective force acting between the adjusting magnet devices are avoided. The corrective force reaches a maximum when the two complementary magnetic poles of the adjusting magnet devices reach a minimum distance from each other as a result of rotation. If the rotation continues, the corrective force initially decreases again until the next magnetic pole pair interacts with each other. The periodic action of force peaks can cause undesirable vibrations and result in uneven rotation of the rotor. The above-mentioned effects can be significantly reduced by distributing the corrective force acting between the magnetic poles of the two complementary adjusting magnet devices almost continuously over a portion of the circumference of the adjusting magnet device, preferably over its entire circumference.

[0041] A spiral arrangement of the magnetic poles is particularly preferred, in which the interaction of the first magnetic poles at one axial end of the adjustment magnet device continues as seamlessly as possible from the interaction of the last magnetic poles at the other axial end of the adjustment magnet device. To this end, the spiral line traced out by the magnetic poles around the rotor makes one complete revolution or an integer number of revolutions. In this case, the first and last magnetic pole pairs of the adjustment magnet device behave as if they were directly adjacent, continuing the spiral. Therefore, there is no significant interruption in the interconnection or corrective force action between the adjustment magnet devices during rotor rotation.

[0042] One or more of the adjusting magnet devices can be connected to the shaft by a corresponding support device. For this purpose, the support device, which is particularly preferably an aluminum sleeve, is arranged on the shaft in a suitable manner. If the adjusting device is first manufactured on the support device and then pressed or otherwise attached to the respective shaft using the latter, this considerably simplifies the design of the rotor or electric motor as a whole. In addition to inexpensive production, this is also associated with easier maintenance and repair. For these purposes, the adjusting magnet device can be removed from the shaft with little effort and repaired or replaced outside the electric motor.

[0043] The invention also applies to a vacuum pump driven by an electric motor according to the invention. The vacuum pump according to the invention is in particular a rotary piston pump, a roots pump or a screw pump. Typically, the vacuum pump according to the invention has at least two displacement elements that are driven in rotation by an electric motor. However, the pump is not limited to a specific type of displacement element. It is also possible to combine different displacement elements, for example in the form of several downstream pump stages.

[0044] The vacuum pump according to the invention is especially designed for medium and low pumping speeds. Preferably, it has a pumping speed of 50 m 3 / h pumping speed.

[0045] In a special embodiment, at least one of the replacement elements has an additional rotor magnet device so that the rotor magnetic coupling is also present in the pump chamber. Alternatively or additionally, the respective shaft adjustment magnet device or additional adjustment magnet device can be provided on or in the shaft replacement element, thereby further increasing the integration and thus reducing the size of the pump. Furthermore, additional coupling and / or adjustment options for compensating for rotational angle misalignment are provided by locating the replacement element in the area where the superimposed rotational vibrations or other synchronous fluctuations or disturbances of the synchronous operation of both rotors have the greatest adverse effect.

[0046] It is preferred to provide a corresponding sensing device for detecting the rotational position or rotational speed of the rotor. In particular, the vacuum pump has a corresponding sensor circuit which interacts with a complementary transmitter magnet of the rotor. In a particularly preferred embodiment, at least one of the rotor's adjusting magnet devices comprises a magnet which performs the function of a transmitter magnet in such an arrangement.

[0047] The invention will be explained in more detail below using exemplary embodiments, in which each and every feature described and / or shown in the drawings constitutes an independent aspect of the invention, regardless of its combination in the exemplary embodiments or reference in the claims. [Brief explanation of the drawings]

[0048] [Figure 1] 1 is a schematic cross-sectional view of the drive section of an electric motor according to the invention; [Figure 2] 2A and 2B are views corresponding to FIG. 1 and illustrating the electric motor of FIG. 1 in different operating states; [Figure 3] 1 is a schematic longitudinal section through an electric motor according to the invention; [Figure 4A] FIG. 1 is a cross-sectional view of two rotor magnet assemblies. [Figure 4B] FIG. 1 is a cross-sectional view of two adjustment magnet devices. [Figure 5] 1 is a schematic diagram of two rotors of a vacuum pump according to the present invention; [Figure 6]1 is a schematic longitudinal sectional view of a vacuum pump according to the present invention; [Figure 7] FIG. 1 is a schematic longitudinal cross-sectional view of a preferred embodiment of a two-magnet adjustment device. DETAILED DESCRIPTION OF THE INVENTION

[0049] Figure 1 shows a cross-sectional view of an electric motor 1 according to the invention having two shafts 2. In this representation, the cross-sectional plane extends perpendicular to the longitudinal axis or rotation axis of the shafts 2 in the area of ​​the actual electric motor drive, as shown by the dash-dotted line I / II / IVA in Figure 3. The electric motor 1 is preferably designed as a two-shaft synchronous motor.

[0050] The shafts 2 run in particular parallel to one another and each carry a rotor magnet device 3 which is rotationally fixedly connected to the shaft 2. During operation of the electric motor 1, the rotor magnet devices 3 of both shafts serve in particular to drive the counter-rotational movement of the shafts 2. In this case, as shown in Figures 1 and 2, they are arranged on a common stator 4. The stator 4 is designed to generate a magnetic field which interacts with the rotor magnet devices 3 and which causes the rotor magnet devices 3 to rotate in a drive sense when there is a corresponding periodic change in the stator magnetic field.

[0051] Therefore, in the operating state of the electric motor 1, both rotor magnet devices 3 are equally affected by the magnetic field generated by the stator 4. Of course, this does not mean that the shape and / or strength of the magnetic field at the position of both rotor magnets 3 must be identical. Rather, this can be designed differently depending on the application. Nevertheless, when the stator 4 is turned on, i.e., in particular in the energized state, both rotor magnet devices 3 are simultaneously and synchronously affected by the generated magnetic field with respect to all changes or fluctuations of the magnetic field. This ensures that no synchronous fluctuations or speed differences of the two shafts 2 can be expected.

[0052] The stator 4 has a stator interior 5 in which the rotor magnet device 3 is arranged. In the stator interior 5, the magnetic field of the stator 4 is generated by a magnetic field generator 6, preferably by a plurality of magnetic field generators 6. The magnetic field generators 6 are in particular coils that generate a magnetic field when a current flows through them. The number and arrangement of the magnetic field generators 6 can influence the shape and local magnetic field strength of the magnetic field in the stator interior 5.

[0053] The stator interior 5 is formed in particular in a housing 7. The housing 7 can extend right up to the stator interior 5. However, embodiments are also possible in which the housing 7 merely serves as an outer casing for the moving and conductive components and thus serves to protect the user. The stator interior 5 is finally formed, and its shape is greatly influenced by the arrangement of the magnetic field generators 6. Functionally, the stator interior 5 is the area surrounded by the magnetic field generators 6 and where the magnetic fields that drive the rotor magnet device 3 are generated. However, as shown in Figures 1 and 2, a section of the housing 7 adapted as precisely as possible to this can be advantageous in terms of thermal and / or electromagnetic shielding or for sound insulation.

[0054] During operation of the electric motor 1, the rotor magnet device 3 is set into rotation by the changing magnetic field of the stator 4. As mentioned above, the magnetic field of the stator 4 is generated, inter alia, by a magnetic field generator 6. When a constant direct current flows through the coil used as the magnetic field generator 6, a static magnetic field is generated inside the stator 5, according to which the rotor magnet device 3 aligns itself with respect to its rotational position.

[0055] For this purpose, the rotor magnet devices 3 comprise at least one magnet for interacting with the magnetic field of the stator 4. Each of the rotor magnet devices 3 therefore has at least two magnetic poles 8, namely a magnetic north pole N and a magnetic south pole S. Now, when an external magnetic field of sufficient strength is applied in the area of ​​the rotor magnet device 3, the magnetic poles 8 align themselves according to this field, causing the rotor magnet device 3 to rotate together with the shaft 2. Periodic changes in the external magnetic field in each case further align the magnetic poles, so that the rotational movement continues and can be maintained continuously.

[0056] In the absence of an external magnetic field, in particular the stator magnetic field, the interaction of the magnetic poles 8 of two adjacently arranged rotor magnet devices 3 becomes apparent. The rotor magnet devices 3 align themselves with respect to their rotational angular position so that the two different magnetic poles 8 of the two rotor magnet devices 3 face each other and are spaced as close as possible according to the diagram in Figure 1. This interaction results in a coupling effect between the rotor magnet devices 3 in the sense of a magnetic gear.

[0057] In the presence of the magnetic field generated by the stator 4, both the above-mentioned interactions, i.e. the reaction of the magnets or magnetic poles 8 to the external magnetic field and the interconnection of the magnetic poles 8 of the complementary rotor magnet devices 3, occur competitively together. For disturbance-free operation, the manufacture of electric motors 1 typically aims to ensure that the alignment of the rotor magnet devices 3 with the magnetic field of the stator 4 corresponds as closely as possible to the alignment of the rotor magnet devices 3 with the magnetic field of the magnetic poles 8 of each complementary rotor magnet device 3. In this case, the alignment of the rotor magnet devices 3 as shown in Figure 1 is to be expected even when the (static) stator magnetic field is activated.

[0058] However, in practice, due to manufacturing tolerances and limited assembly accuracy, the case shown in FIG. 2 frequently occurs when the stator 4 generates a constant magnetic field, for example, by passing a DC current that does not change over time. Since the external magnetic field generated by the stator 4 is generally greater in magnitude than the coupling between the magnetic poles 8 of the rotor magnet devices 3, they are primarily aligned with the external magnetic field in this case. The case shown in FIG. 2 occurs when the rest positions of the rotor magnet devices 3, with respect to the external magnetic field on the one hand and the magnetic fields of the other rotor magnet devices 3 on the other hand, deviate from each other for manufacturing reasons. In this case, the rotor magnet devices 3 reach a position that approximately corresponds to the rest position with respect to the stronger magnetic field of the stator 4. However, this position represents a deviation from the rest position with respect to the magnetic interaction of the rotor magnet devices 3. Similarly, this imbalance persists during rotation of the rotor magnet devices 3 in a dynamically changing stator magnetic field, especially when the magnetic field generator 6 is energized in a periodically changing manner.

[0059] The above-described deflection of the rotor magnet devices 3 relative to their rest positions with respect to their interconnections results in a tensile force in the form of a resulting relative force equivalent to the spring tension in a deflected mechanical spring. This force generates a relative torque between the rotor magnet devices 3 or the shaft 2, respectively. This can be problematic in that a vibration system is formed due to the application of the mutual tensile force of the rotor magnet devices 3, especially at high speeds of the electric motor 1. During operation of the electric motor 1, this can result in superimposed rotational vibrations of the rotor magnet devices 3 or the shaft 2 relative to each other. As the amplitude of this superimposed rotational vibration increases, the coupling of the rotor magnet devices 3, and therefore the synchronization of the rotational movements of both shafts 2, increasingly deviates from the desired range. This can be particularly detrimental if the vibration system or the superimposed rotational vibration begins to resonate at a certain speed. The increase in vibration amplitude can in such cases result in a collision or destruction of the components driven by the electric motor 1.

[0060] Therefore, in the present invention, at least one adjusting magnet device 9 is arranged on each of the two shafts 2. The two adjusting magnet devices 9 preferably form a complementary cooperating pair.

[0061] The adjusting magnet devices 9 are arranged on the shaft 2 in addition to the rotor magnet devices 3, as exemplarily shown in Figure 3. At least one of the adjusting magnet devices 9 is arranged in particular outside the stator. In the illustration of Figure 3, this is made visually clear by the housing 7 being limited in the axial direction to the area of ​​the rotor magnet device 3. However, it is understood that the housing 7 can also surround the adjusting magnet device 9 as well as other parts of the electric motor 1.

[0062] The effectiveness 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 rotation relative to the associated shaft 2 or can be changed in terms of its rotational angular position relative to each complementary adjusting magnet device 9 of the respective other shaft 2. For this purpose, the adjusting magnet device 9, which itself also rotates during rotation of the shaft 2, is fastened to the shaft 2 in such a way that it can be changed in terms of its rotational angular position relative to the shaft 2 and thus relative to the complementary adjusting magnet devices 9 of the other shafts 2, and can be fixed in the changed position.

[0063] 4A and 4B show the relative orientation of the rotor magnet device 3 and the adjustment magnet device 9. Here, FIG. 4A corresponds to a cross section through the rotor magnet device 3 corresponding to the situation shown in FIG. 2, but does not include the housing 7 or other devices surrounding the stator 4. It can be seen that the magnetic poles 8 of the two rotor magnet devices 3 that 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 current left rotor magnet device 3 closest to the current right rotor magnet device 3 will be aligned as a reference magnet or reference pole, with its center point indicating the point closest to the right rotor magnet device 3. The center point of the mentioned magnetic north pole N is geometrically related to the circumferential direction in this example. Functionally, this is in particular the point where the magnetic field lines appear vertically and / or with the highest density. The same applies correspondingly to the magnetic south pole S of the other rotor magnet device 3. The rest position will ultimately correspond to the alignment of the rotor magnet devices 3 shown in FIG. 1.

[0064] The case of mutual pulling force application of rotor magnet devices 3 shown in Fig. 4A can be compensated for or at least reduced to an acceptable level by the adjustment magnet device 9 provided by the present invention, including its negative consequences as described above. Fig. 4B shows a cross section passing through the adjustment magnet device 9 shown in Fig. 3 according to the cross section plane IVB. Compared with Fig. 4A, it can be seen that the adjustment magnet device 9 is also rotated by a certain relative angle with respect to a position corresponding to the rest position due to the magnetic poles 8 of the adjustment magnet device 9. Here, in addition to the coupling force F2 acting between the rotor magnet devices 3, a certain corrective force F1 acts between the adjustment magnet devices 9.

[0065] When statically considering the mutual pulling force application of the rotor magnet devices 3 shown in Figure 4A, the corrective force F1 generates a relative torque between the adjustment magnet devices 9 that opposes the relative torque caused by the coupling force F2 as a result of the runout of the rotor magnet device 3 relative to its rest position. According to the illustration in Figure 3, the rotor magnet devices 3 and the adjustment magnet devices 9 of the common shaft 2 are rotationally coupled to each other through the common shaft. Ideally, the undesired torque caused by the coupling force F2 and the counter torque generated by the corrective force F1 by the adjustment magnet devices 9 thus largely balance each other with respect to the shaft 2.

[0066] The extent to which the application of undesirable pulling forces of the rotor magnet device 3 shown in Figure 4A occurs cannot generally be predicted with sufficient accuracy. The solution according to the invention therefore allows for adjustment of the rotational angle positions of the adjusting magnet devices 9 relative to one another in order to adapt the corrective force F1 or the counter torque caused thereby to the respective application conditions in each individual case.

[0067] When considered dynamically, i.e., when the shaft 2 rotates during operation of the electric motor 1, the formation of the above-mentioned superimposed rotational vibrations can occur. If the amplitude and therefore the relative rotation angle of the rotor magnet devices 3 increase in the course of this rotational vibration, the adjusting magnet devices 9 also rotate more strongly relative to each other due to their coupling with the respective rotor magnet devices 3. Depending on the basic relative arrangement of the complementary adjusting magnet devices 9, the corrective force F1 at high amplitudes will induce a correspondingly increased torque between the shafts 2 in the opposite direction to the vibrations, as a result of which the destructive rotational vibrations will be damped and completely weakened.

[0068] In the above procedure, it is advantageous if the correction force F1 is greater than or at least equal to the coupling force F2. This can be seen in particular by comparing two pairs of complementary rotor magnet devices and adjustment magnet devices 9. Alternatively or additionally, this condition can also apply to the sum of all resulting correction forces F1 together and to the sum of all resulting coupling forces F2 together (when multiple adjustment magnet devices 9 and / or rotor magnet devices 3 are provided).

[0069] 4A and 4B, it can be seen that the rotor magnet device 3 and the adjustment magnet device 9 do not need to have the same number of magnetic poles 8. Rather, the respective numbers depend on how finely the coupling between the rotor magnet devices 3 or the adjustment ability of the correction effect of the adjustment magnet device 9 is desired for a particular application.

[0070] Each of the rotor magnet device 3 and / or the adjustment magnet device 9 comprises at least one magnet, thereby providing a magnetic pole 8. The magnets are preferably sintered and / or may be attached to the shaft 2 or to a support device of a separate rotor magnet device 3 or adjustment magnet device 9, not shown in detail for clarity, by adhesive bonding, pressing, shrinking on or otherwise with the material, force locking, and / or form fitting.

[0071] Particularly preferably, the rotor magnet device 3 and / or the adjusting magnet device 9 of the electric motor 1 according to the invention have a magnetic multipole. For reasons of simplicity, we choose here the representation of a magnetic quadrupole (FIGS. 1, 2, 4A) or an octapole (FIG. 4B). However, in principle, an n-pole, i.e. a higher order multipole, is also possible, in which case, according to the invention, there is no fundamental upper limit to the number of magnetic poles 8. An octapole, more preferably a 12-pole, and particularly preferably a 24-pole, has proven to be a particularly good compromise between the required design effort and good functional effect. The above-mentioned values ​​correspond in particular to the lower limit of the preferred number of poles of the multipole.

[0072] The magnets of the rotor magnet device 3 and / or the adjusting magnet device 9 are, in particular, permanent magnets, which generate a magnetic field independently of an external power source and thus exert a coupling or corrective effect. However, in a preferred embodiment, at least one magnet of the rotor magnet device 3 and / or the adjusting magnet device 9 is designed as an electromagnet, preferably with one or more contact brushes. Alternatively or additionally, such electromagnets can also be designed for contactless operation, in particular by means of induction. Furthermore, the induced eddy currents can also contribute to counteracting synchronous fluctuations. Thus, the strength of the corrective force F1 and / or the coupling force F2 can, in particular, be continuously influenced and / or the associated effect can be switched on / off in each case. It is understood that permanent magnets and electromagnets can be provided in one rotor magnet device 3 or adjusting magnet device 9 or in combination in different rotor magnet devices 3 / adjusting magnet devices 9.

[0073] In particular for the adjustment magnet device 9, but also for the rotor magnet device 3, a cylindrical shape is advantageous with regard to the rotational movements they make during operation of the electric motor 1. The adjustment magnet device 9 and / or the rotor magnet device 3 can therefore have a cylindrical base body, in which case the axis of rotational symmetry of the cylinder is parallel to or coincides with the longitudinal axis of rotation of the shaft 2, as shown in particular in FIG.

[0074] The basic shape of the base body of the adjustment magnet device 9 or rotor magnet device 3, which is cylindrical on average, does not exclude the possibility of one or more elements protruding radially from the basic cylindrical shape, in particular in the form of a disk-like structure. In this case, a design that is approximately rotationally symmetrical with respect to a cross section perpendicular to the rotation axis is advantageous. Figure 7 shows an example of an embodiment of a corresponding adjustment magnet device. Here, in particular, the magnetic poles 8 are located in the radially outer areas of the protruding elements.

[0075] The formation of a disk-shaped structure with intervening free spaces, in this case in the form of circumferential annular grooves, allows the spatial interleaving of the associated magnetic poles 8 without risk of mechanical collision of the components even in the case of strong synchronous fluctuations.

[0076] In the preferred embodiment shown, one magnetic north pole N of each adjustment magnet device 9 is located between two magnetic south poles S of the complementary adjustment magnet device 9, and vice versa. In this way, the adjustment magnet devices 9 couple more tightly to each other than would be the case with a simple opposing arrangement of the magnetic poles 8, i.e., without the intertwining shown here. Therefore, a greater corrective force can be exerted in the event of a synchronous fluctuation between the shafts 2. As a result of the rotation of the adjustment magnet devices 9, the magnetic north poles N and the magnetic south poles S alternately move to their closest positions, so that the ratio of magnetic north poles N to magnetic south poles S shown in FIG. 7 is periodically reversed in each case.

[0077] It will be appreciated that irregular or asymmetric arrangements of protruding elements and corresponding free spaces may be provided, deviating from the description according to Figure 7. Furthermore, one or both of the adjustment magnet devices 9 may comprise a number of separate axially spaced disks or rings or the like which interact with each other in the manner described above.

[0078] Conversely, in order to achieve the most compact possible design, the adjusting magnet device 9 and / or the rotor magnet device 3 can alternatively or additionally be integrated into the shaft 2. For this purpose, the shaft 2 can be correspondingly reduced in diameter in the area of ​​the respective adjusting magnet device 9 or rotor magnet device 3, so that in said area no components of the adjusting magnet device 9 or rotor magnet device 3 protrude beyond the maximum radius of the shaft 2.

[0079] Furthermore, it is by no means necessary to arrange the adjusting magnet devices 9 close to the rotor magnet devices 3 in the manner shown in Figure 3. 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.

[0080] 1, 2, 4A and 4B may suggest that the rotor magnet device 3 or adjustment magnet device 9 has a plurality of magnets or poles 8 along its circumference, but of a constant design in the axial direction. However, the invention also allows for designs in which the adjustment magnet device 9 is provided with a plurality of magnets, in particular of different designs. In particular, this may be a series of magnets arranged preferably in rings around the shaft 2, whereby the number of poles 8 in each ring may be different.

[0081] Furthermore, it is possible not only to provide magnets directly adjacent in the axial direction, but also to provide magnets offset in the axial direction, or in particular to set the spacing of ring-shaped magnet groups, so that the construction requirements can be taken into account depending on the individual application.

[0082] The axially offset magnets can be offset by different rotation angles, in which case in particular an oblique interlocking of the magnets or poles 8 is possible, preferably in the form of a spiral arrangement of the poles 8 around the shaft 2, whereby a nearly continuous effect of the corrective force F1 occurs with greater running smoothness.

[0083] Furthermore, several axially offset and independently adjustable magnets or magnet clusters of adjusting magnet devices 9, as well as multiple adjusting magnet devices 9 on the shaft 2, can also be used to react to disturbance phenomena other than pure rotational vibrations. These include, for example, superimposed bending or torsional vibrations of the shaft 2.

[0084] The support device for the magnets of the adjusting magnet device 9 or rotor magnet device 3 and / or for the adjusting magnet device 9 or rotor magnet device 3 itself is not shown in detail for reasons of simplicity but is designed in particular as a sleeve. Preferably, an aluminum sleeve is used here. Particularly preferred is an embodiment in which a support device is provided that supports at least one of the adjusting magnet devices 9 as a whole so that it can first be completely manufactured and then attached to the shaft 2 using the support device. In particular, one or more magnets, preferably in the form of bar magnets, can be inserted into the sleeve.

[0085] The support device, especially a sleeve-like one, can further serve as a heat sink to cool the magnet, which would otherwise, in the case of a permanent magnet, be at risk of thermal demagnetization if the temperature rises too high during operation.

[0086] The electric motor 1 according to the invention is particularly suitable for driving a vacuum pump 10, as exemplarily shown in FIG. 6. In such a vacuum pump 10, the electric motor 1 serves to drive two rotors 11, which are shown in a schematic plan view in FIG. 5 as a two-shaft synchronous motor. In addition to the shaft 2, the rotor 11 of the vacuum pump 10 also includes at least one rotor magnet device 3 and one adjusting magnet device 9, in particular one or more displacement elements 12. In the example shown here, the displacement elements 12 are designed as screws for a screw pump. Here, a non-compressible embodiment is shown by way of example, in which the screws have a constant pitch. It will be understood that designs with variable pitch, in particular for compression, can also be provided. Displacement elements 12 in the form of, for example, rotating or rolling pistons, or based on a comparable principle, are also possible.

[0087] According to the schematic and exemplary representation of Fig. 6, a vacuum pump 10 according to the invention is provided, in particular for driving two rotors 11 by an electric motor 1 according to the invention, where the function of the above-mentioned adjusting magnet device 9 is used. 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 the housing 7 of the electric motor 1.

[0088] Furthermore, the shaft 2 of the rotor 11 extends through the pump housing 13 and is rotatably mounted therein. The displacement element 12 is arranged at the front of the pump housing 13. They cooperate there so that a pumping medium, for example a fluid, preferably a gas, to be evacuated from the sealed space, is sucked into the pump housing 13 through the suction port 14 and is further conveyed by the displacement element 12. In the conveying direction beyond the displacement element 12, the conveyed fluid then leaves the pump housing 13 through an outlet connector. In the example shown here, the outlet connector is arranged perpendicular to the image plane and is therefore not shown in the present cross-sectional view.

[0089] Preferably, the replacement elements 12 do not come into contact with each other or with the pump housing 13 during operation. Nevertheless, sufficient sealing must be ensured between the replacement elements 12 and relative to the pump housing 13. Therefore, very small gap distances are used here between the relevant components. The above-mentioned problems, with the occurrence of synchronization fluctuations, synchronization errors between the rotors 11, and especially with increasing overlapping rotational vibrations of the rotors 11, can therefore immediately have a significant impact on the operation of the vacuum pump 10.

[0090] In a particularly preferred embodiment, at least one of the replacement elements 12 can have an additional rotor magnet device 3. In this way, the coupling between the two rotors 11 can be strengthened, if each interacting complementary replacement element 12 further forms another magnetic gear with a corresponding rotor magnet device 3.

[0091] Alternatively or additionally, in a preferred embodiment, one or more adjusting magnet devices 9 may be integrated into the replacement element 12. This may be one of the primary adjusting magnet devices 9 or an additional adjusting magnet device 9. Corrective action by the adjusting magnet device 9 can thus act directly at the point where the negative consequences first become apparent in the event of a fault of the type mentioned above.

[0092] The electric motor 1 and / or the vacuum pump 10 may or may further comprise a control device 15, in particular an electronic control device, by means of which it is possible to detect and / or monitor, for example, the rotational speed of the rotor 11, the strength and / or phase of the stator magnetic field, the delivery flow rate of the vacuum pump 10, the noise level in the environment of the vacuum pump 10, the power consumption and / or temperature values ​​of the electric motor 1. Furthermore, it is also possible to control the above-mentioned and / or other parameters by means of the control device 15.

[0093] Respective devices can be provided for detecting the rotational speed and / or rotational position of one or both rotors 11. For this purpose, the vacuum pump 10 preferably has a corresponding sensor circuit, which is in particular integrated into the control device 15. The sensor circuit can be used to read out a sensor magnet, which indicates to the sensor circuit or the control device 15 a complete or partial rotation of the rotor. A corresponding transmitter magnet is preferably integrated into at least one of the adjusting magnet devices 9, so that no additional components need to be added to the rotor 11 for monitoring the rotational movement. Particularly preferably, the magnet or magnetic pole 8 of the adjusting magnet device 9 is recognized as a transmitter magnet by a complementary sensor circuit. [Explanation of symbols]

[0094] 1 electric motor 2 shafts 3 Rotor magnet device 4 Stator 5 Inside the stator 6. Magnetic Field Generator 7. Housing 8 magnetic poles 9. Adjustment magnet device 10. Vacuum pump 11 Rotor 12 Replaced Elements 13 Pump housing 14 Suction nozzle 15 Control Devices N magnetic north pole S magnetic south pole

Claims

1. An electric motor (1), in particular a two-axis synchronous motor, preferably for operating a vacuum pump (10), comprising two rotor magnet devices (3) respectively arranged on two parallel shafts (2), the rotor magnet devices (3) being arranged on a common stator (4) in the operating state of the electric motor (1) so as to interact with each other for mutual coupling with respect to rotational angular position, at least one adjusting magnet device (9) is arranged on each of the two shafts (2), and at least one of the adjusting magnet devices (9) is rotationally adjustable relative to the associated shaft (2) and / or has a variable rotational angular position relative to the complementary adjusting magnet device (9) of the respective other shaft (2) in order to compensate for the forces acting between the rotor magnet devices (3) of the parallel shafts (2) during operation of the electric motor (1) by applying a corrective force that is phase-shifted with respect to the coupling force between the rotor magnet devices (3) with respect to the rotational angular position; An electric motor (1) characterized in that:

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

4. 4. An electric motor according to claim 1, characterized in that at least one of the rotor magnet devices (3) and / or at least one of the adjusting magnet devices (9) comprises one or more magnets, in particular sintered and / or bonded and / or pressed magnets.

5. 5. Electric motor according to any one of claims 1 to 4, 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.

6. 6. Electric motor according to any one of claims 1 to 5, characterized in that at least one of the adjusting magnet devices (9) comprises an electromagnet.

7. At least one of said adjusting magnet devices (9) has a cylindrical base body, and / or At least one of the adjusting magnet devices (9) has one or more radially protruding elements.

7. An electric motor according to any one of claims 1 to 6.

8. 8. Electric motor according to any one of claims 1 to 7, characterized in that at least one of the adjusting magnet devices (9) is integrated into the shaft (2).

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

11. 11. An electric motor according to claim 10, characterized in that the magnets of the adjusting magnet device (9) are rotated relative to one another around the shaft axis, in particular so as to result in a spiral arrangement of identical magnetic poles (8) around the shaft axis.

12. 12. Electric motor according to any one of claims 1 to 11, characterized in that a support device, in particular a sleeve, for supporting at least one of the adjusting magnet devices (9) is arranged on the shaft (2).

13. In a vacuum pump, in particular a rotary lobe pump or a screw pump, having at least one electric motor (1) for rotating at least two displacement elements (12), The electric motor (1) is designed according to any one of claims 1 to 12. A vacuum pump characterized by:

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

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

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