Electric motor and vacuum pump

Abstract

The invention relates to an electric motor, in particular for a vacuum pump, having two magnetically coupled shafts. According to the proposed solution, a corrective force can be adjusted on each shaft by means of a calibration magnet arrangement, by which the negative effects due to errors in the magnetic coupling can be balanced.

Description

Technical Field

[0001] This invention relates to an electric motor having the features described in the preamble of claim 1. The invention also relates to a vacuum pump as described in the preamble of claim 13. Background Technology

[0002] One common industrial application of electric motors is the multi-axis electric motor, which drives multiple shafts synchronously. A typical application, particularly for electric motors with two shafts, is the pump, where two opposing rotating compression elements cause the pump's delivery power. This includes screw pumps, Roots pumps, or telescopic piston pumps, as well as screw compressors. In these pumps, the shafts run in opposite directions. The compression elements, such as the screw spindle, engage with each other as closely as possible during rotation. However, the compression elements should not actually touch, as this will negatively impact operation in the form of wear, noise development, and increased power consumption. Especially given the typically high rotational speeds of such pumps, precise manufacturing, balancing, and orientation of the moving parts are crucial. Due to the required sealing, the clearance width in the area of ​​the compression elements is dimensionally very small. Therefore, only small manufacturing tolerances are required, and there are high demands on the synchronicity of the rotational movements of the two shafts.

[0003] Different methods are known from the prior art for synchronizing two shafts. For example, the shafts can be mechanically coupled, for instance, by means of a gear transmission mechanism. In this case, it is usually sufficient to drive only one shaft, with the other shaft driven via a transmission mechanism. However, this approach has disadvantages, namely, increased wear, operating noise, and power consumption due to the mechanical contact of the components in the coupling link. In addition to the relatively large space requirements, this solution typically requires adequate lubrication, which in turn necessitates a safe and durable seal of the squeegee space (Schöpfraum). Due to the high structural cost, this method is relatively expensive.

[0004] One alternative is to electronically regulate the rotational speed and relative phase of the shafts. However, especially at high speeds, very precise regulation with low latency is required. Besides the correspondingly powerful regulating electronics, the structural cost is relatively high due to the intensive sensing equipment used for both shafts.

[0005] The drawbacks of the above solution are partially overcome by using a motor in which two shafts are arranged in a common stator field. Here, the stator field acts simultaneously on two rotor magnet devices, each connected to a shaft. Therefore, the two rotor magnet devices are always subjected to possible fluctuations in the stator field in the same manner. This largely avoids corresponding synchronization fluctuations.

[0006] Furthermore, the rotor magnet devices, through the coupling of the rotational motion of the shaft caused by the adjacent arrangement of the rotor magnet devices, thus form a magnetic drive mechanism.

[0007] The problem here is that the two magnetic fields (the stator field and the corresponding magnetic field of the other rotor magnet device) act substantially independently of each other on each rotor magnet device. Due to limitations in calibration accuracy in practice, it is possible that the resting position of the shafts relative to the static stator field does not perfectly coincide with the resting position of the rotor magnet devices relative to their magnetic interactions. The field strength of the stator field is typically higher than the coupling effect of the rotor magnet devices relative to each other. Therefore, when the stator field is activated, the two shafts in the above situation are always offset by a certain rotational angle relative to their resting positions relative to each other.

[0008] Corresponding to the case of a tensioned spring, there is tension in the rotor magnet assembly in the form of a force, which is transmitted to the shaft as a relative torque. This torque also exists when the stator field changes, i.e., when the shaft is driven. During pump operation, small synchronization fluctuations in this case can develop into superimposed torsional vibrations, which affect the synchronous rotation of the shaft and can therefore cause significant disturbances. Such torsional vibrations occur in a problematic manner, especially in relatively small devices with relatively long shafts or in systems with single-sided support. Furthermore, plastics (such as PEEK) are often used to manufacture pump components due to their chemical resistance. However, compared to metallic materials, plastics generally have lower density and higher elasticity, which is conducive to structural vibrations within the material.

[0009] Since the rotation of the shafts cannot be individually and electronically adjusted within a shared stator field, alternative solutions must be employed to combat disruptive torsional vibrations. For example, the amplitude of such torsional vibrations can be limited by a mechanical emergency transmission mechanism that operates together without contact under normal conditions. The relative rotation of the shafts is thus stopped, for example, by the contact of gears engaged with each other. However, this leads to significant noise development on the one hand, and increased maintenance costs after a short period due to gear wear on the other.

[0010] Damping torsional vibrations by shifting the resonant frequency will, in particular, require adapting the mass of the involved components. However, this method is not equally applicable to all rotational speeds. Furthermore, excessively lightweight structures are accompanied by structural instability, while excessively heavy structures lead to an undesirable increase in energy demand. Summary of the Invention

[0011] Against this backdrop, the object of the present invention is to provide an electric motor having two shafts in which the rotation of the shafts is synchronized in a particularly reliable manner and, in particular, avoids the aforementioned problems.

[0012] The above objective is achieved by an electric motor having the features of claim 1 and a vacuum pump having the features of claim 13.

[0013] By means of at least one calibration magnet device on each of the two shafts of the electric motor according to the invention, the aforementioned magnetic tension, which takes the form of a force acting between the rotor magnet devices of the two shafts, can be balanced. For this purpose, an anti-torque is generated between the two shafts through the magnetic interaction between the calibration magnet device of one shaft and the complementary calibration device of the corresponding other shaft. This anti-torque is preferably used here as a correction in the sense that, when the stator field is activated, at least substantially no force acting between the rotor magnet devices based on rotational angles relative to their relative rest positions acts between them.

[0014] The calibration magnet device preferably has a structure similar to that of the rotor magnet device. For example, the calibration magnet device includes at least one magnet whose poles can interact with the poles of a complementary calibration magnet device. However, the number, arrangement, and / or orientation of the magnets can vary individually. It has proven particularly suitable for magnets or poles to be arranged in a ring, preferably at equal intervals, around an axis.

[0015] Regarding relative rotation, the torque caused by the shift in rotational angle corresponds to the deflection against the spring force in a vibrating system. If the combined torque is almost zero, the system does not tend to develop superimposed torsional vibrations, even at high speeds, which can increase up to a critical range depending on resonance conditions. If the amplitude of such torsional vibrations is too large, the magnetic coupling between the rotor magnets may become out of sync, thus no longer ensuring synchronous operation of the two shafts. For example, in the case of a pump, this could cause collisions between the rotating compression elements, which, in addition to increased wear and operating noise, can lead to pump failure in severe cases.

[0016] If relative synchronization fluctuations occur between the shafts during operation, the calibration magnets rotate relative to each other. According to the invention, this results in an increase in the corrective force between the corresponding mutually associated magnetic poles of the calibration magnets, a force that resists torsional vibrations without wear.

[0017] In conjunction with this invention, the group of all components that rotate together with the shaft during pump operation is collectively referred to as the "rotor". In addition to the shaft itself, this also includes, in particular, rotor magnet devices, calibration magnet devices, possible compression elements and / or other components associated with the shaft, which are connected to other parts of the shaft or rotor such that the components rotate together with the electric motor during operation.

[0018] The degree to which the two rotors are tensioned relative to each other (i.e., rotated) with respect to their mutual magnetic interaction is essentially related to unavoidable tolerances in the manufacturing of the components and in the assembly of the electric motor. This degree is therefore almost impossible to predict accurately. For this reason, at least one calibration magnet in the calibration magnet assembly is rotatably fixed to the relevant shaft such that at least one calibration magnet can be adjusted relative to the relevant shaft by means of rotation. Alternatively or additionally, the adjustability of the calibration magnet can be expressed in that the calibration magnet can be varied in terms of its rotational angular position relative to the complementary calibration magnet of the corresponding other shaft. The specific calibration of the correction position of the calibration magnet can therefore be performed according to individual cases.

[0019] While it is not mandatory for the corresponding two interacting calibration magnet devices of a complementary pair to be adjustable in the manner described above, this is provided in the preferred embodiment. This allows for easy adjustment of the correct balance position of (multiple) calibration magnet devices. Furthermore, it supports the manipulation of the device, for example, if one of the calibration magnet devices is difficult for the user to reach due to structural realities.

[0020] In the case of a rotor magnet device, the mutual influence of the calibration magnet devices preferably also causes coupling of the rotor according to the principle of the magnetic drive mechanism. In addition to its balancing effect, the calibration magnet device also contributes to the stable synchronization of the rotor in this way, for example, to avoid the aforementioned superimposed torsional vibrations.

[0021] In addition to the components that actually interact magnetically (i.e., one or more magnets), the calibrating magnet device also includes other elements, such as those for fixing to the shaft, holding the magnets together, and / or especially for adjustment in the form of rotation and / or axial movement. The same applies to rotor magnet devices.

[0022] In addition to the rotor magnet assembly and calibration magnet assembly arranged as part of the drive in the stator field, the rotor of the electric motor according to the invention, or the rotor of a pump having the electric motor according to the invention, also has an additional rotor magnet assembly outside the stator for further magnetic coupling of the rotor. According to the invention, the adjustable calibration magnet assembly can also be implemented in combination with the rigid rotor magnet assembly. Preferably, the aforementioned function of the calibration magnet assembly, i.e., in particular the static and / or dynamic balancing of undesirable relative torques of the rotors relative to each other, can be satisfied by the portion adjustable relative to the shaft rotation, while the portion rigidly connected to the shaft is used only to enhance the relative coupling of the rotors.

[0023] It goes without saying that multiple calibration magnet devices can be provided for each axis. The calibration magnet devices for the axes are designed differently, for example, by including different numbers of magnets. Thus, in some applications, more precise adjustments for balancing forces or balancing torques can be made.

[0024] Preferably, at least one of the calibration magnet devices in each shaft is arranged outside the stator. Thus, the calibration magnet device is not subjected to additional forces generated by the stator field. The balancing function of the calibration magnet device can therefore be performed independently of the remaining forces acting on the rotor.

[0025] Functionally, a distinction should be made between the corrective force acting between the calibration magnet devices and the coupling force acting between the two complementary rotor magnet devices. This distinction is not contradictory to the coupling that also occurs due to the interaction of the complementary calibration magnet devices. The corrective force, in particular, causes a targeted adjustment of the relative rotational angle between the calibration magnet devices. As the rotor rotates during operation, the corrective force between the two calibration magnet devices preferably exhibits a phase shift relative to the coupling force between the two rotor magnet devices. Tension in the coupling force can, for example, cause an acceleration of the rotor's rotational motion, which is braked by the corrective force acting with the phase shift.

[0026] The coupling force is nominally used only for the synchronous rotor. Currently, the corrective force therefore functions particularly to balance errors in the coupling force's fluctuations, orientation, and / or phase. These errors can be both static and dynamic. In the latter case, the formation of superimposed torsional vibrations as explained above is prevented through balancing.

[0027] In a preferred embodiment, the corrective force between the complementary calibration magnet devices is greater than or equal in magnitude to the coupling force acting between the two complementary rotor magnet devices. In this way, the balanced corrective force can act in a particularly effective manner. In particular, when the maximum achievable corrective force is significantly greater than the coupling force, the relative synchronization fluctuations and the resulting superimposed torsional vibrations decay rapidly, preferably before the torsional vibrations increase significantly or before the rotational movement of the rotors relative to each other reaches a critical level.

[0028] The rotor magnet assembly and / or calibration magnet assembly of the electric motor according to the invention has only one magnet in its simplest embodiment. However, embodiments with multiple magnets are particularly preferred to ensure reliable coupling of the rotor in the case of the rotor magnet assembly and, furthermore, more accurate calibration in the case of the calibration magnet assembly. The one or more magnets can be integrally and / or, in the sense of a multi-piece embodiment, constituted as multiple individual components and installed or mounted on, especially bonded to, the rotor magnet assembly or calibration magnet assembly. Therefore, the corresponding components can be manufactured in a simple and cost-effective manner. Sintered and / or plastic-bonded magnets are preferred.

[0029] At least one rotor magnet device and / or at least one calibration magnet device in the rotor magnet assembly preferably include magnetic multipoles. Since each magnet is already a dipole, the term magnetic multipole currently refers to a design including at least one magnetic quadrupole, i.e., an embodiment in which at least four magnetic poles are provided. However, higher-order magnetic multipoles are particularly preferred, preferably at least eight-fold multipoles, more preferably at least twelve-fold multipoles, and particularly preferably at least 24-fold multipoles. However, according to the invention, there is no upper limit to the number of magnetic poles. Therefore, in principle, n-fold multipoles can be used in the sense of any order of multipole. Depending on the number of poles in the rotor magnet device or calibration magnet device, correspondingly more precise coupling of the rotor or finer adjustments to the calibration magnet device can be achieved to balance the aforementioned tensions.

[0030] It goes without saying that the rotor magnet assembly and / or calibration magnet assembly in the electric motor according to the invention need not always have the same number of magnets or poles. However, the rotor magnet assemblies or calibration magnet assemblies that are correspondingly complementary to each other preferably correspond to each other in the number and aspect of their magnets or poles / or in other design aspects. In particular, a design scheme in which a pair of complementary rotor magnet assemblies or calibration magnet assemblies that are at least substantially identical or symmetrical is preferred.

[0031] Considering the low structural cost, permanent magnets are particularly suitable for use in rotor magnet devices and / or calibration magnet devices. Besides cost-effective ferromagnets, neodymium-containing magnets are especially preferred, as they are characterized by high remanence and are therefore particularly suitable for compact implementations of rotor or calibration magnet devices. Alternatively to or added to the permanent magnet, the calibration magnet device may also have an electromagnet. This allows not only adjustment of the relative position of the calibration magnet device with respect to a complementary calibration magnet device of the corresponding other rotor, but also adjustment of the field strength and thus the correction force.

[0032] Furthermore, the design of the electromagnet allows the calibration magnet device to be switched on and off as needed, if necessary. For example, in conjunction with the electronic regulation of an electric motor, especially regarding speed, if synchronization fluctuations or asynchrony are determined, correction can be intervened by activating the electromagnetic action of the calibration magnet device. In particular, this allows for the suppression of superimposed torsional vibrations at an early stage, preferably before the vibration amplitude reaches a critical level, thus preventing normal operation from being disrupted.

[0033] Regarding rotational motion, at least one calibration magnet in the calibration magnet device has a columnar base. Here, the longitudinal axis of the column, in particular the axis of rotation parallel to the rotor axis, extends and preferably coincides with it. The magnetic poles of the calibration magnet device are preferably arranged equidistantly around the circumference of the column.

[0034] Alternatively or additionally, at least one of the calibration magnet devices in the calibration magnet assembly may also deviate from a purely cylindrical shape, particularly by having radially protruding, preferably annular, elements or multiple such elements, especially axially spaced elements. In principle, the position of the magnet or pole can therefore be further radially outward, reducing the distance between the calibration magnet devices of the two rotors without increasing the diameter of the calibration magnet devices overall, i.e., along the entire axial length. In this way, despite the further outward movement of the poles, the moment of inertia of the adjusting device remains relatively low, and the risk of disruptive imbalance is reduced. This results in smoother rotor operation and better controllability of the rotational motion.

[0035] A particularly preferred design of the invention is that the two complementary calibration magnet devices each have at least one radially projecting element, particularly an axial segment, which at least partially projects radially from the respective axis such that the corresponding regions of the complementary calibration devices at least partially overlap in their axial projections. This can be achieved, for example, by one or more disc-shaped structures of the calibration magnet devices, which are respectively engaged in the corresponding free space, preferably annular groove, of the respective complementary calibration magnet devices. If the magnetic poles of the calibration magnet devices are arranged radially outward in the corresponding regions (i.e., particularly in the disc-shaped structures), this results in the magnetic poles of the complementary calibration magnet devices spatially interleaving with each other. In this case, the magnetic interaction no longer occurs solely through the opposing tangential surfaces of the calibration magnet devices. Instead, the interleaved arrangement allows the magnetic poles to be further introduced into the field of the corresponding associated magnetic poles of the complementary calibration magnet devices. Thus, the magnetic coupling between the calibration magnet devices, i.e., particularly the maximum achievable correction force, is enhanced. In the case of multiple, especially axially offset, radially protruding elements (e.g., in the form of multiple parallel disk-shaped structures), the magnetic poles of the calibration magnet device preferably penetrate into the free space provided by the complementary calibration magnet device, such that the magnetic fields of the two or more magnetic poles adjacent to the free space act on them accordingly, thereby further enhancing the coupling.

[0036] Higher integration can be achieved by integrating at least one calibration magnet device into the relevant shaft. In this case, the calibration magnet device has no or at least only a small portion protruding beyond the center radius of the shaft in the region of the calibration magnet device. This is particularly advantageous when the shafts are arranged in close proximity. Especially in this case, but independently, the corresponding integration of at least one rotor magnet device is also preferred. The integration of not only the calibration magnet devices but also the rotor magnet devices need not be arranged on the same shaft; they can also be arranged on different shafts.

[0037] Another starting point for influencing the error balance in rotor coupling via the rotor magnet assembly is provided in such a way that at least one of the calibration magnet assemblies is axially movable along the relevant shaft. For example, this allows for a response to localized imbalances or temporary and / or periodic torsion of the rotor or shaft along the axial direction. Alternatively or additionally, at least one of the rotor magnet assemblies arranged in the stator may also be arranged to be axially movable and / or offset relative to a complementary rotor magnet assembly.

[0038] According to the present invention, a calibration magnet device does not necessarily need to 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 an axis. In a preferred embodiment, multiple axially offset magnets and / or magnet groups may also be provided, which are assigned to a calibration magnet device. Thus, such a calibration magnet device may also have multiple magnet groups arranged in a ring, wherein different magnets or magnet groups may be arranged either directly adjacent to each other or spaced apart from each other along the axial direction. Furthermore, different magnet groups of a calibration magnet device may also have different numbers of magnetic poles. Preferably, the magnet groups can also be adjusted independently of each other by adjusting their rotational angular position relative to the complementary calibration magnet device of the corresponding other axis.

[0039] Uniform rotor operation is achieved through continuous magnetic interaction, particularly between two complementary calibration magnet devices. For this purpose, in the case of calibration magnet devices with magnets axially offset from each other, these magnets rotate relative to each other about an axis. Particularly preferably, this results in a helical or spiral arrangement of corresponding identical magnetic poles around the axis. In this case, as the rotor rotates, the two magnetic poles of the relatively complementary calibration magnet devices interact first. If rotation continues, these magnetic poles will again move away from each other, while a stronger interaction occurs between axially adjacent magnetic poles. Due to the helical arrangement of corresponding identical magnetic poles extending around the axis, this sequence continues axially and restarts after one complete rotation.

[0040] The rotational adjustment of the calibration magnet device relative to the relevant axis at a specific rotational angle to balance the aforementioned interference effects can affect all magnetic poles, even in the case of a helical arrangement. However, this avoids the periodic occurrence of peak values ​​of the corrective force acting between the calibration magnet devices. The corrective force is at its maximum when the two complementary magnetic poles of the calibration magnet device reach their minimum relative distance due to rotation. If rotation continues, the corrective force first decreases again until the next pair of magnetic poles interacts with each other. The periodic action of the force peaks can cause undesirable vibrations, which lead to unstable operation of the rotor. The almost continuous distribution of the corrective force acting between the magnetic poles of the two complementary calibration magnet devices on a portion of the periphery of the calibration magnet device, preferably across its entire periphery, can significantly reduce the aforementioned effects.

[0041] A helical arrangement of the magnetic poles is particularly preferred, wherein the interaction of the first magnetic pole at one axial end of the calibration magnet device follows, as seamlessly as possible, the interaction of the last magnetic pole at the other axial end of the calibration magnet device. For this purpose, the helix around the rotor, described by the magnetic poles, preferably implements a complete loop or an integer number of loops. Thus, in this case, the first pair of magnetic poles and the last pair of magnetic poles of the calibration magnet device behave as if they were directly adjacent and the helix continues. Therefore, when the rotor rotates, there is no significant interruption in the mutual coupling or the application of corrective forces between the calibration magnet devices.

[0042] One or more calibration magnet devices can be connected to the shaft via corresponding carriers. For this purpose, the carrier (particularly preferably a sleeve made of aluminum) is arranged suitably on the shaft. If the calibration device is first manufactured on the carrier and then moved or otherwise positioned onto the corresponding shaft using that carrier, this significantly simplifies the overall structure of the rotor or electric motor. In addition to cost-effective manufacturing, this also results in easier maintenance and repair. For these purposes, the calibration magnet device can be removed from the shaft with minimal effort and repaired or replaced externally to the electric motor.

[0043] Currently, vacuum pumps with an electric motor according to the invention for driving also have their own inventive significance. The vacuum pump according to the invention is specifically, in particular, a rotary piston pump, a telescopic piston pump, a Roots pump, or a screw pump. Typically, the vacuum pump according to the invention has at least two compression elements driven by an electric motor. However, here, the pump is not limited to a specific type of compression element. Combinations of different types of compression elements, for example, combinations of compression elements in the form of multiple downstream pump stages, are also possible.

[0044] The vacuum pump according to the invention is particularly designed for medium and low delivery power. Preferably, the vacuum pump has a capacity of less than 50 m³ / s. 3 / h suction capacity.

[0045] In one particular design, at least one of the compression elements has an additional rotor magnet device, thus ensuring magnetic coupling of the rotors also exists in the suction space. Alternatively or additionally, a corresponding shaft calibration magnet device or an additional calibration magnet device may also be provided at or within the compression element of the shaft. This further reduces integration and thus the size of the pump. Furthermore, the possibility of additional coupling and / or calibration for balancing angular error positions through arrangement in the compression element region begins where the superimposed torsional vibrations or other synchronous fluctuations or disturbances during the synchronous operation of the two rotors have the strongest negative impact.

[0046] To detect the rotor's rotational position or speed, a corresponding detection device is preferably provided. In particular, the vacuum pump has a corresponding sensor circuit that interacts with a complementary transmitter magnet of the rotor. In a particularly preferred embodiment, at least one calibration magnet device in the rotor's calibration magnet device includes a magnet that, in such an arrangement, functions as a transmitter magnet. Attached Figure Description

[0047] The invention will now be explained in more detail with the aid of embodiments. All features described and / or illustrated in the drawings constitute independent aspects of the invention, regardless of their combination in the embodiments or references to the claims.

[0048] in: Figure 1 A schematic cross-sectional view of the electric motor according to the invention in the drive region is shown. Figure 2 It shows Figure 1 The corresponding Figure 1 The diagram shows the electric motor in alternative operating states. Figure 3 A schematic longitudinal section of an electric motor according to the present invention is shown. Figure 4A A cross-sectional view of the two rotor magnet devices is shown. Figure 4B Cross-sectional views of two calibration magnet devices are shown. Figure 5 A schematic diagram of the two rotors of the vacuum pump according to the present invention is shown in top view. Figure 6 A schematic longitudinal section of a vacuum pump according to the present invention is shown, and Figure 7 A schematic longitudinal section of a preferred embodiment of two calibration magnet devices is shown. Detailed Implementation

[0049] exist Figure 1 The diagram shows an electric motor 1 with two shafts 2 according to the present invention in cross-sectional view. In the current illustration, the cutting plane extends perpendicularly to the longitudinal or rotational axis of the shafts 2 in the region of the actual electric motor drive, as shown below. Figure 3 The dotted lines I / II / IVA are used to indicate this. The electric motor 1 is preferably constructed as a dual-shaft synchronous motor.

[0050] Shaft 2 extends parallel to each other and carries rotor magnet assemblies 3, which are connected to shaft 2 in an anti-rotational manner. During operation of the electric motor 1, the rotor magnet assemblies 3 on both shafts drive the shaft 2, specifically in opposite directions, rotational motion. Currently, the rotor magnet assemblies are arranged in a common stator 4, as shown... Figure 1 and2 As shown in the figure, the stator 4 is configured to generate a magnetic field that interacts with the rotor magnet device 3 and, in the sense of driving, causes it to rotate under the corresponding periodic changes of the stator field.

[0051] When the electric motor 1 is running, the two rotor magnet devices 3 appear to be affected by the magnetic field generated by the stator 4. However, this does not mean that the shape and / or strength of the magnetic field at the positions of the two rotor magnet devices 3 must be the same. Rather, this can be designed differently depending on the application and the structural configuration. Nevertheless, all changes or fluctuations in the field experienced by the two rotor magnet devices 3 when the stator 4 is energized (i.e., especially when the stator is powered on) are simultaneously and synchronously subjected to the generated field. This ensures that, in this respect, synchronous fluctuations or speed differences between the two shafts 2 are not expected.

[0052] The stator 4 has an internal space 5, in which the rotor magnet assembly 3 is arranged. Within the internal space 5, the magnetic field of the stator 4 is generated by a field generator 6, preferably by multiple field generators 6. The field generator 6 is particularly a coil that generates a magnetic field when current flows through it. The shape and local field strength of the magnetic field within the internal space 5 can be influenced by the number and arrangement of the field generators 6.

[0053] The stator internal space 5 is specifically constructed within the housing 7. Here, the housing 7 can extend into the stator internal space 5. However, it is also possible to implement an embodiment where the housing 7 is merely an outer covering for movable and conductive components and, in this respect, serves to protect the user. The stator internal space 5 is ultimately formed by the arrangement of the field generator 6 and is decisively influenced in its shape. Functionally, the stator internal space 5 is the region surrounded by the field generator 6, in which a magnetic field for driving the rotor magnet device 3 is generated. However, as... Figure 1 and Figure 2 As shown, the sections of housing 7 that are adapted as precisely as possible to this can be advantageous in terms of thermal and / or electromagnetic shielding or noise isolation.

[0054] When the electric motor 1 is running, the rotor magnet assembly 3 is placed in rotation due to the changing magnetic field of the stator 4. As described above, the field of the stator 4 is generated in particular by the field generator 6. If the coil used as the magnetic field generator 6 is circulated with a constant direct current in a constant manner, a static magnetic field is generated in the internal space 5 of the stator, according to which the rotor magnet assembly 3 is oriented about its rotational position.

[0055] For this purpose, the rotor magnet device 3 includes at least one magnet for interacting with the field of the stator 4. Accordingly, the rotor magnet device 3 has at least two magnetic poles 8 (magnetic north pole N and magnetic south pole S). If an external field of sufficient strength is now applied to the region of the rotor magnet device 3, the magnetic poles 8 will align according to the field, thereby causing the rotor magnet device 3 to rotate together with the shaft 2. Further alignment of the magnetic poles 8 by periodic changes in the external field allows the rotational motion to continue and be maintained continuously.

[0056] In the absence of an external field, especially a stator field, the interaction of the magnetic poles 8 of two adjacent rotor magnet devices 3 becomes apparent. The rotor magnet devices 3 are oriented with respect to their rotational angles such that the two distinct magnetic poles 8 of the two rotor magnet devices 3 face each other and are spaced as close as possible to each other, according to... Figure 1 The diagram illustrates this. This interaction causes coupling between the rotor magnet devices 3 in the sense of a magnetic transmission mechanism.

[0057] In the presence of a magnetic field generated by the stator 4, both of the aforementioned interactions (i.e., the response of the magnet or magnetic pole 8 to the external field and the mutual coupling of the magnetic poles 8 of the complementary rotor magnet device 3 relative to each other) occur in a competitive manner. Regarding interference-free operation, in principle, when manufacturing the electric motor 1, it is attempted to make the orientation of the rotor magnet device 3 according to the field of the stator 4 and the field of the magnetic poles 8 correspond as closely as possible to the corresponding complementary rotor magnet device 3. In this case, even when the (static) stator field is activated, it is expected that... Figure 1 The orientation of the rotor magnet device 3.

[0058] However, when the stator is energized by, for example, a time-invariant direct current, to generate a constant magnetic field in stator 4, manufacturing tolerances and practically limited assembly precision are required. Figure 2 The situation shown frequently occurs. 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 assembly 3, the rotor magnet assembly is oriented particularly according to the external field. If the corresponding rest positions of the rotor magnet assembly 3, on the one hand, with respect to the external field and on the other hand, with respect to the magnetic field of another rotor magnet assembly 3, are different from each other due to manufacturing, the following situation arises. Figure 2 The situation is illustrated here. The rotor magnet device 3 occupies a position that largely corresponds to a stationary position relative to the stronger magnetic field of the stator 4. However, this position is a deflection from the stationary position of mutual magnetic interaction between the rotor magnet device 3 and the stator 4. If the field generator 6 is energized in a particularly periodically varying manner, this imbalance continues in the dynamically changing stator field even as the rotor magnet device 3 rotates.

[0059] The deflection of the rotor magnet assembly 3 relative to its mutually coupled resting position generates tension in the form of a composite relative force, corresponding to the spring tension in the deflecting mechanical spring. This force generates a relative torque between the rotor magnet assembly 3 or the shaft 2. This can be particularly problematic at high speeds of the electric motor 1, i.e., due to the tension of the rotor magnet assemblies 3 relative to each other, forming an oscillating system. During the operation of the electric motor 1, superimposed torsional vibrations of the rotor magnet assembly 3 or the shaft 2 relative to each other can occur. As the amplitude of this superimposed torsional vibration increases, the synchronicity of the coupling of the rotor magnet assembly 3 and therefore the rotational motion of the two shafts 2 deviates further and further from the desired range. This is especially critical when the oscillating system or the superimposed torsional vibration resonates at a specific speed. In such a case, due to the increase in vibration amplitude, collisions or even damage to the components driven by the electric motor 1 can occur.

[0060] Here, the invention is employed by arranging at least one calibration magnet device 9 on each of the two axes 2. Each pair of calibration magnet devices 9 preferably forms a complementary and interacting pair.

[0061] Currently, the calibration magnet device 9 is attached to the rotor magnet device 3 and arranged on the shaft 2, as shown below. Figure 3 As exemplarily shown in the diagram. At least one calibration magnet device in the calibration magnet device 9 is here specifically arranged outside the stator 4. Figure 3 In the illustration, this is visually shown by confining the housing 7 in the axial direction to the area of ​​the rotor magnet assembly 3. It goes without saying, however, that the housing 7 could also enclose the calibration magnet assembly 9 and other parts of the electric motor 1.

[0062] The function of the calibration magnet device 9 is based on the following: at least one calibration magnet device in the calibration magnet device 9 can be adjusted by rotation relative to the relevant axis 2, or its rotational angular position relative to a corresponding complementary calibration magnet device 9 on another corresponding axis 2 can be varied. For this purpose, the calibration magnet device 9 is fixed on the axis 2 such that although it rotates along with the axis 2 when the axis 2 rotates, its rotational angular position relative to the axis 2 and therefore relative to the complementary calibration magnet device 9 on the other axis 2 can be varied and fixed in the changed position.

[0063] Figure 4A and Figure 4B The diagram illustrates the relative orientation of the rotor magnet assembly 3 and the calibration magnet assembly 9 with respect to each other. Here, Figure 4A Corresponding to according to Figure 2The diagram shows a cross-section of the rotor magnet assembly 3, but without the surrounding structures of the stator 4 and housing 7. It can be seen that the magnetic poles 8 of the two rotor magnet assemblies 3 closest to each other are not in a position corresponding to a stationary position resulting from their mutual attraction. In this stationary position, the magnetic north pole N of the rotor magnet assembly 3 currently arranged on the left, closest to the rotor magnet assembly 3 currently arranged on the right, is oriented as a reference magnet or reference pole such that its center point is 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 center point is particularly a point where the magnetic field lines appear perpendicular and / or with the highest density. This also applies accordingly to the magnetic south pole S of the other rotor magnet assembly 3. The stationary position ultimately corresponds to the rotor magnet assembly 3 in... Figure 1 The orientation shown.

[0064] exist Figure 4A The tension between the rotor magnet devices 3 shown (including their aforementioned negative consequences) can be compensated for, or at least reduced to an acceptable level, by the calibration magnet device 9 provided according to the invention. Figure 4B The diagram shows the passage through the IVB according to the cutting plane. Figure 3 A cross-section of the calibration magnet device 9 shown. (Comparison) Figure 4A It can be seen that the calibration magnet device 9 has also rotated by a certain relative angle relative to the position corresponding to the stationary position generated by the magnetic pole 8 of the calibration magnet device 9. In addition to the coupling force F2 acting between the rotor magnet devices 3, a certain correction force F1 now acts between the calibration magnet devices 9.

[0065] exist Figure 4A In the static observation of the tension between the rotor magnet devices 3 and each other, a relative torque is generated between the calibration magnet devices 9 by the corrective force F1. This relative torque is opposed to the resultant relative torque, which is caused by the coupling force F2 due to the deflection of the rotor magnet devices 3 relative to their rest positions. According to Figure 3 The diagram shows that the rotor magnet device 3 and the calibration magnet device 9, sharing a common shaft 2, are rotatably coupled to each other via this shaft. Ideally, the undesirable torque caused by the coupling force F2 and the counter-torque about shaft 2 generated by the corrective force F1 via the calibration magnet device 9 are substantially balanced.

[0066] Appear Figure 4A The degree of undesirable tension between the rotor magnet devices 3 and each other, as shown, is often difficult to predict accurately. Therefore, the solution according to the invention allows adjustment of the rotational angular position of the magnet devices 9 relative to each other so that the corrective force F1 or the resulting counter-torque is adapted to the respective application in each case.

[0067] Under dynamic observation, i.e., when shaft 2 rotates during the operation of electric motor 1, the aforementioned superimposed torsional vibrations may occur. If the amplitude (i.e., the relative rotation angle of the rotor magnet device 3) increases during the torsional vibration, the calibration magnet device 9 also twists more strongly relative to each other due to its coupling with the corresponding rotor magnet device 3. Based on the adjustment of the basic relative orientation of the complementary calibration magnet devices 9, the correction force F1 causes a correspondingly increased torque between shafts 2 in the case of high amplitude, pointing in the opposite direction to the vibration, thereby damping and suppressing the torsional vibration.

[0068] In the above process, it is advantageous that the correcting force F1 is greater than or at least equal to the coupling force F2 in magnitude. This can be understood in particular with respect to the comparison of two pairs of complementary rotor magnet devices 3 and calibration magnet devices 9. Alternatively or additionally, this condition may also apply to the sum of all occurring correcting forces F1 and the sum of all occurring coupling forces F2 (if multiple calibration magnet devices 9 and / or rotor magnet devices 3 are provided).

[0069] By comparison Figure 4A and Figure 4B It can be seen that the rotor magnet device 3 and the calibration magnet device 9 do not necessarily have the same number of magnetic poles 8. Rather, the corresponding number depends on how finely the coupling between the rotor magnet devices 3 or the corrective action of the calibration magnet device 9 should be adjusted in the specific application.

[0070] The rotor magnet assembly 3 and / or the calibration magnet assembly 9 each include at least one magnet, which provides magnetic poles 8. The magnets are preferably sintered and / or fixed to the shaft 2 or a separate, but not individually shown, support device of the rotor magnet assembly 3 or the calibration magnet assembly 9 by means of bonding, extrusion, shrinkage or other material fit, force fit and / or form fit.

[0071] Particularly preferably, the rotor magnet device 3 and / or calibration magnet device 9 of the electric motor 1 according to the invention have magnetic multipole. For simplicity, a magnetic quadrupole is currently shown. Figure 1 , Figure 2 , Figure 4A ) or eight-fold multipolar ( Figure 4B However, in principle, n-fold multipoles, i.e., higher-order multipoles, can be involved, where, according to the invention, there is no upper limit in principle for the number of magnetic poles 8. Octave multipoles, more preferably 12-fold multipoles, and particularly preferably 24-fold multipoles have proven to be particularly suitable trade-offs between the desired structural cost and good functional performance. The above values ​​here correspond in particular to the lower limit of the preferred number of poles for multipoles.

[0072] The magnets, particularly permanent magnets, of the rotor magnet device 3 and / or calibration magnet device 9 generate magnetic fields independently of an external energy supply and thus perform coupling or correction functions. However, in a preferred embodiment, the magnets of at least one rotor magnet device 3 and / or at least one calibration magnet device 9 are preferably constructed as electromagnets with one or more contact brushes. Alternatively or additionally, such electromagnets can also be constructed for contactless operation, particularly by means of inductive contactless operation. Furthermore, induced eddy currents also help to resist synchronization fluctuations. Therefore, the strength of the correction force F1 and / or coupling force F2 can be affected, particularly steplessly, and / or the associated effects can be switched on and off accordingly. It goes without saying that permanent magnets and electromagnets can also be combined at the rotor magnet device 3 or the calibration magnet device 9, or at different rotor magnet devices 3 / calibration magnet devices 9.

[0073] Especially for the calibration magnet device 9, but also for the rotor magnet device 3, the columnar shape is advantageous in terms of the rotational motion performed by the electric motor 1 during operation. Accordingly, the calibration magnet device 9 and / or the rotor magnet device 3 can have a columnar base. For example... Figure 3 As shown, the axis of rotational symmetry of the column is parallel to or coincides with the longitudinal axis and the axis of rotation of axis 2.

[0074] The basic columnar shape of the base of the calibration magnet device 9 or the rotor magnet device 3 does not preclude the possibility of incorporating one or more elements that protrude radially from the basic columnar shape, especially elements in the form of a disc-shaped structure. In this case, a design scheme that is generally rotationally symmetric about the cross-section perpendicular to the axis of rotation is advantageous. Figure 7 An exemplary embodiment of a calibration magnet device is shown. Here, in particular, the magnetic pole 8 is located in the radially outer region of the protruding element.

[0075] By constructing a disk-shaped structure (currently in the form of a surrounding annular groove) with free space between them, the magnetic poles 8 that are matched with each other can be spatially interleaved (Verschränkung) without the risk of mechanical collision of components even in the case of strong synchronous fluctuations.

[0076] In the preferred design shown, the magnetic north pole N of the calibration magnet 9 is located between the two magnetic south poles S of the complementary calibration magnet 9, and vice versa. The calibration magnets 9 are thus more strongly coupled to each other than when the magnetic poles 8 are arranged only opposite each other, i.e., without the staggered arrangement shown here. Therefore, a greater corrective force can be applied when synchronous fluctuations occur between the axes 2. Due to the rotation of the calibration magnet 9, the magnetic north pole N and magnetic south pole S are alternately positioned in the closest possible positions to each other, such that... Figure 7The conditions of the North Pole (N) and South Pole (S) shown in the diagram are periodically reversed.

[0077] It goes without saying that, according to Figure 7 Depending on the diagram, protruding elements and corresponding irregular or asymmetrical arrangements of free space can also be provided. Furthermore, one or two calibration magnet devices 9 can also have multiple separate, axially spaced disks, rings, etc., which interact with each other in the manner described above.

[0078] Conversely, alternatively or additionally, the calibration magnet device 9 and / or the rotor magnet device 3 can also be integrated into the shaft 2 to achieve the most compact possible structural form. For this purpose, the shaft 2 can have a correspondingly reduced diameter in the region of the respective calibration magnet device 9 or rotor magnet device 3, thus eliminating any components of the calibration magnet device 9 or rotor magnet device 3 extending beyond the maximum radius of the shaft 2 in the relevant region.

[0079] Furthermore, the calibration magnet device 9 does not need to be used in such a way as Figure 3 The arrangement shown is close to the rotor magnet device 3. According to the invention, corresponding intervals along the axis of shaft 2 are also possible. In a particularly preferred design, at least one calibration magnet device in the calibration magnet device 9 can even be movably constructed in the axial direction, i.e., along shaft 2.

[0080] Figure 1 , Figure 2 , Figure 4A and Figure 4B The cross-sectional view shows that although the rotor magnet device 3 or the calibration magnet device 9 may have a large number of magnets or poles 8 along its periphery, they have a constant structure in the axial direction. However, according to the invention, it is also possible to have a structure in which multiple, especially different, magnets are arranged in the calibration magnet device 9. These magnets can be, in particular, a series of magnets preferably arranged in a ring around the shaft 2, wherein the number of poles 8 in each ring can be different.

[0081] Furthermore, it is also possible to not only arrange directly adjacent magnets in the axial direction, but also to establish gaps between axially offset magnets or especially between groups of toroidal magnets. Thus, the structural practicality can be considered according to various application scenarios.

[0082] Furthermore, the axially offset magnets can also be offset at different rotation angles. Here, in particular, the helical teeth of the magnets or magnetic poles 8, preferably in the form of a helical toothed structure with the magnetic poles 8 arranged around the shaft 2, are possible, thereby allowing the almost continuous action of the corrective force F1 to occur with better quiet operation.

[0083] Furthermore, the multiple axially offset magnets or groups of magnets arranged in the calibration magnet device 9 and adjustable independently, as well as the multiple calibration magnet devices 9 on the shaft 2, can also respond to disturbances other than pure torsional vibrations. Such disturbances include, for example, superimposed bending or torsional vibrations of the shaft 2.

[0084] For simplicity, the support device for the magnet used in calibrating magnet device 9 or rotor magnet device 3, and / or the support device for calibrating magnet device 9 or rotor magnet device itself, which is not shown individually, is particularly constructed as a sleeve. Preferably, an aluminum sleeve is used. A particularly preferred design is one in which the support device serves as an integral support for at least one calibration magnet device in calibration magnet device 9, allowing the calibration magnet device to be manufactured entirely first and then mounted onto shaft 2 by means of the support device. In particular, one or more magnets, preferably in the form of rod-shaped magnets, can be pushed into the sleeve.

[0085] In particular, the sleeve-shaped support device can also be used as a cooling body for cooling the magnet. Otherwise, for example in the case of permanent magnets, there is a risk of thermal demagnetization if the temperature rises too much during operation.

[0086] The electric motor 1 according to the invention is particularly suitable for driving a vacuum pump 10, such as Figure 6 As exemplarily shown in the figure. In such a vacuum pump 10, an electric motor 1, particularly as a dual-shaft synchronous motor, is used to drive two rotors 11, which in Figure 5 The diagram is depicted in a schematic top view. The rotor 11 of the vacuum pump 10, in addition to the shaft 2, includes at least one rotor magnet device 3 and a calibration magnet device 9, and in particular, one or more compression elements 12. In the example shown here, the compression element 12 is configured as a screw for a screw pump. Here, an exemplary non-compression embodiment is shown, in which the screw has a constant pitch. It goes without saying that embodiments with variable pitch can also be provided, especially for compression. Furthermore, compression elements 12 in the form of, for example, rotating or rolling pistons, or compression elements 12 based on similar principles, are also possible.

[0087] Corresponding to Figure 6 The exemplary schematic diagram shows that, in particular, the vacuum pump 10 according to the invention is configured to drive two rotors 11 by means of an electric motor 1 according to the invention. Here, the function of the calibration magnet device 9 described above is used. In the case of the vacuum pump 10 shown here, the parallel rotors 11 extend, on the one hand, in the region of the driving part of the electric motor 1 (i.e., especially in the stator 4) and / or in the housing 7 of the electric motor 1.

[0088] Furthermore, the shaft 2 of the rotor 11 is extended such that it extends through the pump housing 13 and is rotatably supported there. A compression element 12 is arranged in the front portion of the pump housing 13. The compression elements there work together such that the transport medium, such as fluid to be extracted from the enclosed space, preferably gas, is drawn into the pump housing 13 via the suction pipe 14 and further transported by the compression element 12. In the transport direction on the other side of the compression element 12, the transported transport medium then exits the pump housing 13 through a discharge pipe. In the example shown here, this discharge pipe is arranged in a direction perpendicular to the image plane and is therefore not shown in the current cross-sectional view.

[0089] The compression elements 12 preferably do not contact each other or the pump housing 13 during operation. Nevertheless, it is still necessary to ensure a sufficient seal between the compression elements 12 and relative to the pump housing 13. Therefore, an extremely small gap is used between the involved components. The aforementioned problems, such as synchronization fluctuations, synchronization errors between rotors 11, and especially the increased superimposed torsional vibration of rotors 11, can thus act quickly in a manner critical to the operation of the vacuum pump 10.

[0090] In a particularly preferred embodiment, at least one of the compression elements 12 may have an additional rotor magnet device 3. Thus, the coupling between the two rotors 11 can be enhanced if the compression elements 12, which act complementaryly to each other, additionally form an additional magnetic drive mechanism through the corresponding rotor magnet device 3.

[0091] Alternatively or additionally, a preferred design may be that one or more calibration magnet devices 9 are integrated into the compression element 12. The calibration magnet devices may be one of the original calibration magnet devices 9 or additional calibration magnet devices 9. The corrective effect of the calibration magnet devices 9 can thus directly act on the point where, under the influence of the aforementioned interference, the negative consequences would be first noticeable.

[0092] The electric motor 1 or vacuum pump 10 may also have a controller 15, particularly an electronic controller, by means of which, for example, the rotational speed of the rotor 11, the strength and / or phase of the stator field, the delivery rate of the vacuum pump 10, the noise level in the environment surrounding the vacuum pump 10, the power consumption and / or temperature of the electric motor 1 can be detected or monitored. Furthermore, the controller 15 can also be used to adjust the above and / or other parameters.

[0093] To detect the rotational speed and / or rotational position of one or both rotors 11, appropriate devices can be provided. For this purpose, the vacuum pump 10 preferably has a corresponding sensor circuit, which is particularly integrated into the controller 15. The transmitter magnet can be read by means of the sensor circuit, indicating to the sensor circuit or controller 15 the full or partial rotation of the rotor. The corresponding transmitter magnet is preferably integrated into at least one calibration magnet device in the calibration magnet device 9, thus eliminating the need to add additional components to the rotor 11 for monitoring rotational motion. The magnet or pole 8 of the calibration magnet device 9 is particularly preferably sensed as a transmitter magnet by complementary sensor circuitry.

[0094] List of reference numerals 1. Electric motor 2-axis 3. Rotor magnet device 4. Stator 5. Stator internal space 6 Field Generator 7. Casing 8 magnetic poles 9. Magnet calibration device 10 Vacuum Pumps 11 Rotors 12 Extrusion Components 13 Pump casing 14 Suction Connector 15 Controllers N magnetic north pole S is the magnetic south pole.

Claims

1. An electric motor (1) for operating a vacuum pump (10), the electric motor having two rotor magnet assemblies (3) respectively arranged on a shaft (2), wherein, The rotor magnet devices (3) are arranged in a common stator (4) in such a way that the rotor magnet devices interact with each other about their rotational angular positions to couple with each other. Its features are, At least one calibration magnet device (9) is arranged on each of the two axes (2), wherein at least one of the calibration magnet devices (9) is adjustable by means of rotation relative to its respective axis (2) and / or is able to vary in rotational angular position relative to the complementary calibration magnet device (9) of the corresponding other axis (2), wherein at least one of the calibration magnet devices (9) is fixed on the axis (2) such that the calibration magnet device is able to vary in rotational angular position relative to the axis (2) and therefore relative to the complementary calibration magnet device (9) of the other axis (2) and is fixed in the changed position.

2. The electric motor according to claim 1, characterized in that, At least one calibration magnet device in the calibration magnet device (9) of each shaft (2) is arranged outside the stator (4).

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

4. The electric motor according to claim 1 or 2, characterized in that, At least one rotor magnet device (3) and / or at least one calibration magnet device (9) of the rotor magnet device (3) have one or more magnets.

5. The electric motor according to claim 1 or 2, characterized in that, At least one rotor magnet device in the rotor magnet device (3) and / or at least one calibration magnet device in the calibration magnet device (9) have magnetic multipole.

6. The electric motor according to claim 1 or 2, characterized in that, At least one of the calibration magnet devices (9) has an electromagnet.

7. The electric motor according to claim 1 or 2, characterized in that, At least one of the calibration magnet devices (9) has a columnar base, and / or at least one of the calibration magnet devices (9) has one or more radially protruding elements.

8. The electric motor according to claim 1 or 2, characterized in that, At least one of the calibration magnet devices (9) is integrated into the shaft (2).

9. The electric motor according to claim 1 or 2, characterized in that, At least one of the calibration magnet devices (9) is capable of moving axially along the axis (2).

10. The electric motor according to claim 1 or 2, characterized in that, At least one of the calibration magnet devices (9) includes a plurality of magnets arranged in an axial offset manner.

11. The electric motor according to claim 10, characterized in that, The magnets of the calibration magnet device (9) rotate relative to each other about the axis so that the same magnetic poles (8) are arranged in a spiral shape around the axis.

12. The electric motor according to claim 1 or 2, characterized in that, A support device is arranged on the shaft (2) for supporting at least one of the calibration magnet devices (9).

13. The electric motor according to claim 1, characterized in that, The electric motor (1) is a dual-axis synchronous motor.

14. The electric motor according to claim 1, characterized in that, The shaft (2) extends in parallel.

15. The electric motor according to claim 4, characterized in that, The magnet is sintered and / or bonded and / or extruded.

16. The electric motor according to claim 5, characterized in that, The magnetic multipole is at least an eight-fold multipole.

17. The electric motor according to claim 12, characterized in that, The supporting device is a sleeve.

18. A vacuum pump having at least one electric motor (1) for rotating at least two compression elements (12), Its features are, The electric motor (1) is constructed according to any one of the preceding claims.

19. The vacuum pump according to claim 18, characterized in that, At least one of the compression elements (12) has an additional rotor magnet device (3) and / or one of the calibration magnet devices (9) or an additional calibration magnet device (9).

20. The vacuum pump according to claim 18 or 19, characterized in that, At least one of the calibration magnet devices (9) includes a magnet configured as a transmitter magnet for interacting with complementary sensor circuitry.

21. The vacuum pump according to claim 18, characterized in that, The vacuum pump is a rotary piston pump or a screw pump.

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