Rotary atomizer

Abstract

The invention relates to a rotary atomizer (1) for atomizing a coating material (e.g., paint) with a rotor (2, 5) having a rotating magnet (5) and a stationary magnetic sensor (6) for detecting the polarity reversals of the magnetic field of the magnet (5) as it rotates with the rotating rotor (2, 5), wherein the magnetic sensor (6) is arranged within a detection range around the magnet (5) so that the magnetic sensor (6) can detect the rotating polarity reversals of the magnetic field. The invention provides that only electrically poorly conductive materials with a high specific electrical resistance of more than 1 Ω·mm are located within the detection range around the rotating magnet (5). 2 / m, 0.5 Ω·mm 2 / m or 0.1 Ω·mm 2 / m, to avoid interfering induced currents in the detection range, and / or that only electrically conductive materials with a low specific electrical resistance of less than 1 Ω·mm are located outside the detection range around the rotating magnet (5). 2 / m, 0.5 Ω·mm 2 / m or 0.1 Ω·mm 2 / m.

Description

Technical field of the invention

[0001] The invention relates to a rotary atomizer for atomizing a coating agent, in particular for atomizing paint for painting motor vehicle body components. Background of the invention

[0002] In modern paint shops for painting automotive body components, rotary atomizers are most commonly used as application devices. When using such rotary atomizers, it is desirable to determine the rotational speed and direction of rotation in order to enable speed control.

[0003] From DE 102 37 128 A1, a rotary atomizer is known which makes it possible to monitor the rotational speed and direction of rotation during operation. For this purpose, the known rotary atomizer has a rotating reflector disk which is scanned by an optical sensor. However, a disadvantage of this optical speed detection is its susceptibility to interference from contamination of the reflector disk.

[0004] Furthermore, it is known from the prior art to determine the rotational speed of a rotary atomizer acoustically by recording the operating noise of the rotary atomizer in order to derive the rotational speed from it. However, this acoustic speed detection is also susceptible to interference. For example, the background noise occurring during the operation of a rotary atomizer in a paint shop can interfere with the acoustic speed measurement.

[0005] Finally, from DE 10 2021 101 028 A1, it is known to measure the rotational speed of a rotary atomizer using a Wiegand sensor (pulse wire sensor) that detects the reversals of polarity of a rotating magnetic disk. However, this type of rotational speed measurement using a Wiegand sensor is also susceptible to interference, and the technical and physical reasons for this susceptibility have not yet been fully understood. Description of the invention

[0006] The invention is therefore based on the objective of improving the speed detection in a rotary atomizer.

[0007] This problem is solved by a rotary atomizer according to the invention and the main claim.

[0008] The rotary atomizer according to the invention initially comprises, in accordance with known rotary atomizers, a rotatably mounted rotor which rotates around a rotational axis at a specific speed during operation. In a preferred embodiment of the invention, the rotor has an atomizer shaft which has a mounting point at its distal end for a bell-shaped disc, for example in the form of a screw connection for screwing the bell-shaped disc onto the atomizer shaft.

[0009] Furthermore, the rotary atomizer according to the invention, in accordance with the rotary atomizers with a Wiegand sensor described above as prior art, also has a magnet (e.g., a magnetic disc) which rotates with the rotor and has several magnetic poles distributed around its circumference, thus exhibiting a change of poles in the circumferential direction.

[0010] Furthermore, the rotary atomizer according to the invention also includes a magnetic sensor (e.g. Wiegand sensor) for detecting the reversals of the magnetic field of the magnet that occur with the rotating rotor, wherein the magnetic sensor is arranged within a detection range around the magnet so that the magnetic sensor can detect the reversals of the magnetic field.

[0011] The invention is based on the newly acquired technical and physical insight that the rotating polarity reversals of the magnetic field in the materials of the rotary atomizer lead to eddy currents and induce opposing magnetic fields that interfere with the rotational speed measurement by the magnetic sensor (e.g., Wiegand sensor). Thus, at the location of the magnetic sensor (e.g., Wiegand sensor), a useful signal originating from the rotating magnet's polarity reversals is superimposed with a noise signal generated by the induced opposing magnetic fields.

[0012] The invention therefore provides that these disruptive eddy currents and opposing magnetic fields are reduced in order to reduce the susceptibility to interference of the speed detection.

[0013] In the rotary atomizer according to the invention, therefore, only electrically poorly conductive materials with a high specific electrical resistance of more than 1 Ω·mm are preferably located within the detection range around the rotating magnet. 2 / m, 0.5 Ω·mm 2 / m or 0.1 Ω·mm 2 / m to avoid interfering induced currents in the detection range.

[0014] Outside the detection range, however, electrically conductive materials with a low specific electrical resistance of less than 1 Ω·mm can also be present in the rotary atomizer according to the invention. 2 / m, 0.5 Ω·mm 2 / m or 0.1 Ω·mm 2 / m have.

[0015] The rotary atomizer according to the invention is therefore preferably characterized by a material mix, wherein the material mix within the detection range around the rotating magnet consists of electrically poorly conductive materials (e.g. ρ > 0.1 Ω·mm). 2 / m) while outside the detection range around the rotating magnet electrically conductive materials (e.g. ρ 0.1 Ω·mm) 2 / m) can be provided, as is the case with conventional rotary atomizers.

[0016] The aforementioned electrically poorly conductive materials could be, for example, plastic, stainless steel or titanium; however, the invention is not limited to these examples with regard to electrically poorly conductive materials.

[0017] In the preferred embodiment of the invention, the stationary magnetic sensor is spatially separated from the rotating magnet by an air gap, wherein the air gap can have a gap width of at least 0.1 mm, 0.5 mm, 1 mm, 2 mm, 5 mm or 10 mm. The air gap completely prevents the induction of currents and opposing fields in the region of the air gap, since air is electrically insulating.

[0018] Regarding the design of the rotating magnet, there are various possibilities within the scope of the invention, two of which are described below.

[0019] In one embodiment of the invention, the magnet is shaped as a magnetic disk, the magnetic disk being arranged coaxially to the axis of rotation and rotating with the rotor of the rotary atomizer. For example, the magnetic disk can be pressed onto the atomizer shaft, to name just one example. The magnetic sensor is preferably located axially proximal to the magnetic disk and is separated from the magnetic disk in the axial direction by the aforementioned air gap. In this embodiment, the magnetic field in the air gap thus runs essentially axially. The length of the magnetic disk in the axial direction is significantly smaller than the radius of the magnetic disk. Furthermore, it should be noted that the at least one magnet is preferably embedded in an end face of the magnetic disk. In an arrangement of the magnetic sensor in the proximal direction in front of the magnetic disk (i.e.,(on the side of the painting robot and on the side facing away from the bell plate) the at least one magnet is then also embedded in the proximal end face of the magnetic disc.

[0020] In another embodiment of the invention, the rotating magnet is shaped as a magnetic sleeve, which can, for example, be pressed onto the atomizer shaft. The magnetic sensor (e.g., a Wiegand sensor) is radially separated from the rotating magnetic sleeve by the aforementioned air gap. In this embodiment, the magnetic field in the air gap between the rotating magnetic sleeve on the one hand and the stationary magnetic sensor on the other is therefore essentially radial. Consequently, in this embodiment, the magnetic sensor is preferably arranged radially outside the magnetic sleeve. Regarding the design of such a magnetic sleeve, it should be noted that the magnetic sleeve is hollow and has a radial thickness that is significantly smaller than the axial length and / or the radius of the magnetic sleeve.

[0021] In a preferred embodiment of the invention, the magnetic sensor is arranged in an annular space extending circumferentially. For example, the annular space can extend around the entire circumference of the axis of rotation. However, in the preferred embodiment of the invention, the annular space consists of at least one elongated slot that is curved circumferentially and extends only over a portion of its circumference. The magnetic sensor is arranged in the elongated slot, preferably centrally with respect to the circumferential direction, so that the magnetic sensor is surrounded on both sides by the elongated slot in the circumferential direction. Furthermore, it should be noted that the magnetic sensor preferably does not completely fill the annular space (e.g., the elongated slot) in the radial direction, but leaves a radially internal clearance.

[0022] The annular space (e.g., elongated hole) is preferably filled with an electrically insulating material, which largely prevents the induction of eddy currents and opposing magnetic fields near the magnetic sensor, since eddy currents cannot form in the electrically insulating material. Filling the annular space (e.g., elongated hole) with an electrically insulating material is also advantageous to prevent air turbulence within the annular space, which could otherwise occur in a hollow annular space and lead to mechanical power losses. For example, the electrically insulating material in the annular space could be plastic.

[0023] Furthermore, the invention comprises another inventive concept of independent, patentable significance. The disruptive eddy currents and opposing magnetic fields can also be reduced by using a laminated core consisting of numerous sheets that are electrically insulated from one another, so that no eddy current can flow across the sheets. Such laminated cores are already known from transformers and therefore do not need to be described in detail. For example, the laminated core can contain more than 10, 20, 50, or 70 sheets that are electrically insulated from one another.

[0024] In this case, it is possible that the magnetic sensor (e.g. Wiegand sensor) is at least partially located in the laminated core, for example in an axial bore in the laminated core.

[0025] Furthermore, it should be mentioned that the individual laminations of the laminated core preferably lie in a plane containing the rotational axis of the rotary atomizer. The individual laminations are thus preferably arranged circumferentially with respect to the rotational axis. The entire laminated core is therefore preferably arranged in a ring shape and coaxially with the rotational axis of the rotor. Furthermore, at least some of the laminations of the laminated core may be slotted to optimally suppress disruptive eddy currents. The laminations can, for example, be made of a so-called mu-metal, such mu-metals being known from the prior art. Generally, it should be mentioned that the adjacent laminations of the laminated core can each be separated by an air gap, which can also be filled with an electrically insulating material.Furthermore, it should be mentioned that the laminated core is preferably arranged within the detection range around the magnet.

[0026] As mentioned above, the invention aims to minimize interference with speed measurement caused by induced opposing fields. The magnetic field generated by the rotating magnet produces a useful signal with a maximum first magnetic field strength. Conversely, the interfering counter-magnetic field generated by the induced currents produces an interference signal with a second maximum magnetic field strength at the location of the magnetic sensor. The interference suppression measures according to the invention preferably enable a reduction of the second maximum magnetic field strength (interference signal) of the interfering counter-magnetic field to 30%, 20%, 10%, 5%, or even just 2% of the first maximum magnetic field strength of the useful signal generated by the rotating magnet. As a result, the design measures according to the invention improve the useful signal / interference signal ratio in magnetic speed measurement.

[0027] Furthermore, it should be mentioned that various orientations and arrangements of the magnetic sensor within the rotary atomizer are possible within the scope of the invention. For example, the magnetic sensor can be elongated and aligned with its longitudinal axis parallel to the rotational axis of the rotary atomizer. Alternatively, the magnetic sensor can be elongated and aligned with its longitudinal axis radially with respect to the rotational axis of the rotary atomizer.

[0028] With the aforementioned axial alignment of the magnetic sensor parallel to the rotation axis of the rotary atomizer, various arrangements of the magnetic sensor are possible. For example, the magnetic sensor can be positioned axially proximal to the magnetic disk, so that the annular air gap separates the magnetic sensor from the magnetic disk in the axial direction. Alternatively, the magnetic sensor can partially overlap the magnetic disk in the axial direction and be positioned radially outside the magnetic disk at its circumference. In this case, the annular air gap separates the magnetic sensor from the magnetic disk in the radial direction.

[0029] In the aforementioned radial orientation of the magnetic sensor, the invention also provides various possibilities for its arrangement. For example, the magnetic sensor can be arranged axially proximal to the magnetic disk, so that the air gap separates the magnetic sensor from the magnetic disk in the axial direction. In this case, the magnetic sensor then overlaps the magnetic disk in the radial direction. Alternatively, the radially oriented magnetic sensor can also be arranged radially outside the magnetic disk on its circumference, so that the air gap separates the magnetic sensor from the magnetic disk in the radial direction.

[0030] As mentioned above, the magnetic sensor is preferably a Wiegand sensor, as is known from the prior art (e.g., DE 10 2021 101 028 A1). Such Wiegand sensors are also referred to as pulse wire sensors and do not need to be described in more detail, as they are known from the prior art. However, the invention is not limited to a Wiegand sensor with regard to the type of magnetic sensor.

[0031] Furthermore, it should be noted that the rotor preferably incorporates the magnetic sensor as a separate component that is rotationally fixed to the rotor. For example, the magnetic sensor (e.g., a magnetic disc or magnetic sleeve) can be pressed onto the atomizer shaft, to name just one example.

[0032] Furthermore, it should also be mentioned that the rotary atomizer may have a compressed air turbine to drive the rotor, as is the case with conventional rotary atomizers.

[0033] In the preferred embodiment of the rotary atomizer according to the invention, the rotating magnet has several pairs of magnetic north poles and magnetic south poles alternately around its circumference, for example two, three or four pairs of magnetic poles.

[0034] Regarding the aforementioned detection range around the magnet, it should be noted that the detection range along the axis of rotation preferably extends over an axial dimension that can be in the range of 5 mm to 5 cm. In the radial direction, however, the detection range preferably has a radial dimension that can be in the range of 5 mm to 3 cm.

[0035] As mentioned earlier, it is desirable to detect not only the rotational speed but also the direction of rotation in a rotary atomizer. In the rotary atomizer according to the invention, the distribution of the magnetic poles around the circumference of the rotor is therefore preferably not rotationally symmetrical, in order to detect both the rotational speed and the direction of rotation. With a rotationally symmetrical arrangement of the magnetic poles, the pulse sequence supplied by the magnetic sensor contains no information about the direction of rotation of the rotary atomizer. This is different with a non-rotationally symmetrical arrangement of the magnetic poles in the rotor, since the pulse sequence supplied by the magnetic sensor then also contains information about the direction of rotation of the rotary atomizer.

[0036] Furthermore, it should be generally mentioned that the rotary atomizer according to the invention is preferably designed for atomizing paint during the painting of motor vehicle body components. However, the invention is not limited to paints with regard to the coating material to be atomized, but can also be implemented with other types of coating materials. Moreover, the rotary atomizer according to the invention is suitable not only for coating motor vehicle body components, but also for coating other types of components.

[0037] Finally, the invention also includes the novel use of a rotary atomizer according to the invention for atomizing paint, particularly for painting automotive body components. The paint can be, for example, wet paint (liquid paint) or powder paint. Furthermore, it should be noted that the invention is not limited to automotive body components with regard to the components to be painted, but is also suitable for painting other types of components.

[0038] Other advantageous embodiments of the invention are characterized in the dependent claims or are explained in more detail below together with the description of the preferred embodiments of the invention with reference to the figures. Brief description of the drawings Fig. Figure 1A shows a sectional view through a rotary atomizer according to the invention. Fig. Figure 1B shows an enlarged detail view from Fig. 1A. Fig. Figure 2 shows a perspective view of a magnetic disk used in the rotary atomizer according to the invention for speed detection. Fig. Figure 3 shows an axial rear view of the rotary atomizer according to the invention. Fig. Figure 4 shows a magnetic sleeve as an alternative to the magnetic disc according to Fig. 2. Fig. Figure 5 shows a cross-sectional view through a modified rotary atomizer with a laminated core to minimize disruptive eddy currents. Fig. Figure 6 shows an axial rear view of the rotary atomizer according to Fig. 5. Fig. Figure 7 shows a schematic representation of a modified magnetic disk with a non-rotationally symmetric arrangement of the magnetic poles in order to also enable detection of the direction of rotation. Fig. Figures 8-10 show various modifications according to the invention with different arrangements of the magnetic sensor. Detailed description of the drawings

[0039] The exemplary embodiment of a rotary atomizer 1 according to the invention, as shown in the drawings, will now be described below, wherein Fig. Figure 1A shows a sectional view of part of the rotary atomizer 1.

[0040] Thus, the rotary atomizer 1 initially has a conventional atomizer shaft 2, which is part of a rotor and rotates around a rotational axis 3 during operation (see Fig. 3, Fig. 5 and Fig. 6) rotates. The atomizer shaft 2 is driven in the conventional manner by a compressed air turbine, which is not shown for the sake of simplicity.

[0041] The atomizer shaft 2 is rotatably mounted within an atomizer housing 4 in a conventional manner, although the bearings for the atomizer shaft 2 are not shown.

[0042] A magnetic disk 5 is pressed onto the atomizer shaft 2, which has several magnetic north poles N and magnetic south poles S distributed around its circumference, as can be seen in particular from Fig. 2 is evident.

[0043] The rotational speed is measured by a Wiegand sensor 6, which is located in the atomizer housing 4, with the Wiegand sensor 6 being separated from the magnetic disk 5 by an air gap 7. The magnetic field generated by the magnetic disk 5 passes through this air gap 7. B→ so essentially axial, i.e. parallel to the axis of rotation 3 of the atomizer shaft 2. As the atomizer shaft 2 rotates with the magnetic disk 5, the direction of the magnetic field continuously changes. B→ in the air gap 7, i.e., polarity reversals occur in the air gap 7, which are detected by the Wiegand sensor 6 in the conventional manner.

[0044] Furthermore, it should be mentioned that the Wiegand sensor 6 is arranged within a detection range 8 around the magnetic disk 5 so that it can detect the polarity changes generated by the rotating magnetic disk 5 in the air gap 7. The detection range 8 is shown here only schematically to facilitate understanding of the invention. In reality, the detection range 8 does not have a circular or spherical shape.

[0045] The air gap 7 has a gap width b = 10 mm in the axial direction. This is advantageous because, due to the electrically insulating effect of the air, no eddy currents or opposing magnetic fields can be induced within the air gap 7, thus largely preventing interference with the speed measurement.

[0046] Furthermore, it should be mentioned that the Wiegand sensor 6 is arranged in the atomizer housing 4 in an elongated hole 9 which extends circumferentially, as shown from Fig. As can be seen in Figure 3, the Wiegand sensor 6 is arranged centrally within the elongated hole 9 with respect to its circumference, so that it is surrounded on both sides by the elongated hole 9. Furthermore, it should be noted that the Wiegand sensor 6 does not completely fill the elongated hole 9 radially, but leaves a radial clearance 10 on its inner side. The arrangement of the Wiegand sensor 6 within the elongated hole 9 is advantageous because no interfering induction currents or opposing fields can be induced within the elongated hole 9, thus also reducing the susceptibility of the speed measurement to interference. It should also be noted that the elongated hole 9 can be filled with an electrically insulating material, such as plastic. This is advantageous to prevent air turbulence within the elongated hole 9, which would lead to mechanical power losses.

[0047] Fig. Figure 4 shows an alternative to the magnetic disc 5 according to Fig. 2 a magnetic sleeve 11, which can, for example, be pressed onto an atomizer shaft. The magnetic sleeve 11 also has several magnetic north poles N and magnetic south poles S distributed around its circumference in order to generate pole reversals when rotating, as is also the case with the magnetic disk 5 according to Fig. 2 is the case. However, the associated Wiegand sensor is preferably arranged radially on the outside and separated from the magnetic sleeve 11 by an air gap. In this variant with the magnetic sleeve 11, the magnetic field in the air gap between the magnetic sensor and the magnetic sleeve 11 runs essentially in a radial direction.

[0048] Fig. Figure 5 shows a modification of a rotary atomizer 1 according to the invention, which largely corresponds to the embodiment described above, so that reference is made to the preceding description to avoid repetition, with the same reference numerals being used for corresponding details.

[0049] A special feature of this modified embodiment is that a laminated core 12 is arranged in the atomizer housing 4, which has numerous sheets 13 distributed around the circumference, as shown in particular by Fig. As can be seen in Figure 6, the adjacent laminations 13 are each separated from one another by an air gap 14. The laminated core 12 thus prevents eddy currents from flowing in the circumferential direction, since the adjacent laminations 13 are insulated from each other. The laminated core 12 therefore also contributes to avoiding the disruptive eddy currents that are generated when the magnetic disk 5 rotates. The Wiegand sensor 6 is arranged in an axial bore 15 that passes through the laminated core 12. Furthermore, it is evident from Fig. Figure 6 shows that the individual sheets 13 of the sheet stack 12 each lie in a plane that contains the axis of rotation 3 of the rotary atomizer 1. In the sectional view according to Fig. 6 the individual sheets 13 thus run in a radial direction.

[0050] Furthermore, it shows Fig. 7 a modification of the magnetic disk 5 according to Fig. 2, where the same reference numerals are used for corresponding details, so that, to avoid repetition, reference is first made to the preceding description. Fig. 2 is referred to.

[0051] A special feature of this embodiment is that the magnetic north poles N and the magnetic south poles S are not arranged rotationally symmetrically around the circumference of the magnetic disk 5. This offers the advantage that not only is rotational speed measurement possible, but also the direction of rotation. Due to the non-rotationally symmetrical arrangement of the magnetic north poles N and the magnetic south poles S, the pulse sequence supplied by the magnetic sensor contains not only information about the rotational speed, but also information about the direction of rotation of the rotary atomizer.

[0052] The invention is not limited to the preferred embodiments described above. Rather, the invention also includes variants and modifications that likewise make use of the inventive concept and therefore fall within the scope of protection. In particular, the invention also claims protection for the subject matter and the features of the dependent claims independently of the respective referenced claims and especially also without the features of the main claim. The invention thus comprises various aspects of the invention that enjoy independent protection. This applies in particular to the idea of ​​using a laminated core in a rotary atomizer to minimize eddy currents. The idea of ​​using a laminated core in a rotary atomizer to avoid eddy currents is therefore also realizable within the scope of the invention without the specific arrangement of electrically poorly or highly conductive materials within or between the laminated core and the atomizer.outside the detection range.

[0053] Finally, the Fig. 8-10 different variations according to the invention with different arrangements of the magnetic sensor 6. These variations largely correspond to the embodiments described above, so that, to avoid repetition, reference is made to the preceding description, using the same reference numerals for corresponding details.

[0054] In the embodiment according to Fig. 8 the magnetic sensor 6 is elongated and its longitudinal axis is aligned parallel to the rotational axis 3 of the rotor, as is also the case in the embodiment according to Fig. 1A is the case. In the embodiment according to Fig. In 1A, however, the magnetic sensor 6 is arranged axially proximal to the magnetic disk 5, whereas in this embodiment, the magnetic sensor 6 partially overlaps the magnetic disk 5 axially and is arranged radially outside the magnetic disk 5 at its circumference. The air gap 7 is therefore annular and separates the magnetic sensor 6 from the magnetic disk 5 in the radial direction.

[0055] At Fig. In figure 9, the magnetic sensor 6 is also elongated. However, in this case, the magnetic sensor 6 is radially aligned with its longitudinal axis relative to the axis of rotation 3. The magnetic sensor 6 is arranged radially outside the magnetic disk 5 on its circumference and separated from the magnetic disk 5 in the radial direction by the annular air gap 7.

[0056] Finally, it also shows Fig.10. The magnetic sensor 6 is arranged in a radial orientation with respect to the rotation axis 3 of the rotor. However, the magnetic sensor 6 is arranged axially proximal to the magnetic disk 5 and partially overlaps the magnetic disk 5 in the radial direction. The annular air gap 7 thus separates the magnetic sensor 6 from the magnetic disk 5 in the axial direction. Advantages of the invention

[0057] The following is a brief summary of some of the advantages of the invention. • The invention enables interference-resistant detection of rotational speed and direction of rotation in a rotary atomizer, which in turn enables reliable control and leads to shorter downtimes. • Furthermore, the invention enables higher signal reserves for more stable control. • Furthermore, the speed detection is less sensitive to disruptive external influences. • In addition, the rotary atomizer according to the invention has a higher efficiency and thus has lower air consumption across all operating points due to lower eddy current losses or lower air eddy current losses. • Finally, the design features (e.g., air gap, elongated hole) allow for a lighter construction of the rotary atomizer. Reference symbol list 1 rotary atomizer 2 atomizer shaft 3 Rotation axis of the rotor 4 atomizer housings 5 magnetic discs 6 Wiegand sensor 7 Air gap between the magnetic disk and the Wiegand sensor 8 Detection range 9 elongated holes for mounting the Wiegand sensor 10 Radial clearance on the inside of the Wiegand sensor 11 Magnetic sleeve 12 sheet metal packages 13 sheets 14 air gaps between the adjacent sheets of the sheet metal stack 15 Axial bores in the sheet metal package for mounting the Wiegand sensor b Gap width of the air gap between the magnetic disk and the Wiegand sensor N Magnetic North Poles S Magnetic South Poles Magnetic field in the air gap QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 102 37 128 A1

[0003] DE 10 2021 101 028 A1 [0005, 0030]

Claims

[1] Rotary atomizer (1) for atomizing a coating agent, in particular for atomizing paint for painting motor vehicle body components, with a) a rotatably mounted rotor (2, 5, 11) which rotates around a rotational axis (3) at a specific speed during operation, b) a magnet (5, 11) which rotates with the rotor (2, 5, 11) and has a plurality of magnetic poles (N, S) distributed over the circumference and thus a pole change in the circumferential direction, and c) a magnetic sensor (6) arranged in a fixed position in the rotary atomizer (1) for detecting the pole changes of the magnetic field rotating with the rotating rotor (2, 5, 11) (B→) of the magnet (5, 11), wherein the magnetic sensor (6) is arranged within a detection range (8) around the magnet (5, 11), so that the magnetic sensor (6) detects the circulating pole changes of the magnetic field (B→) can detect, characterized by , d) that within the detection range (8) around the rotating magnet (5, 11) there are only electrically poorly conductive materials with a high specific electrical resistance of more than 1 Ω·mm 2 / m, 0.5 Ω·mm 2 / m or 0.1 Ω·mm 2 / m to avoid disturbing induction currents in the detection area, and / or e) that only outside the detection range (8) around the rotating magnet (5, 11) there are electrically highly conductive materials with a small specific electrical resistance of less than 1 Ω·mm 2 / m, 0.5 Ω·mm 2 / m or 0.1 Ω·mm 2 / m. [2] Rotary atomizer (1) according to claim 1, characterized by a combination of materials a) the electrically poorly conductive materials within the detection range (8) around the rotating magnet (5, 11) and b) the electrically highly conductive materials outside the detection range (8) around the rotating magnet (5, 11). [3] Rotary atomizer (1) according to one of the preceding claims, characterized by that the electrically poorly conductive material within the detection range (8) around the rotating magnet (5, 11) is plastic, stainless steel or titanium. [4] Rotary atomizer (1) according to one of the preceding claims, characterized by , a) that the stationary magnetic sensor (6) is spatially separated from the rotating magnet by an air gap, and b) that the air gap preferably has a gap width (b) of at least 0.1 mm, 0.5 mm, 1 mm, 2 mm, 5 mm or 10 mm. [5] Rotary atomizer (1) according to claim 4, characterized by , a) that the magnet (5) is shaped as a magnetic disc (5), b) that the magnetic sensor (6) is axially separated from the magnetic disc (5) by the air gap (7), c) that the magnetic field (B→) in the air gap (7) runs essentially axially, d) that the magnetic sensor (6) is preferably arranged proximally in the axial direction with respect to the magnetic disc (5), e) that the magnetic disc (5) is preferably arranged coaxially to the rotation axis (3). [6] Rotary atomizer (1) according to claim 4, characterized by , a) that the magnet (11) is shaped as a hollow magnet sleeve (11), b) that the magnetic sensor is radially separated from the magnetic sleeve (11) by the air gap, c) that the magnetic field in the air gap is essentially radial, d) that the magnetic sensor is preferably arranged radially outside the magnetic sleeve (11). [7] Rotary atomizer (1) according to one of the preceding claims, characterized by , a) that the magnetic sensor (6) is arranged at least partially in an annular space (9) which extends in the circumferential direction, b) that the annular space (9) optionally extends over the entire circumference around the axis of rotation (3), c) that the annular space (9) optionally has at least one elongated hole (9) which extends only over part of the circumference around the rotation axis (3), d) that the magnetic sensor (6) is optionally arranged centrally in the elongated hole (9) with respect to the circumferential direction, so that the magnetic sensor (6) is surrounded by the elongated hole (9) on both sides in the circumferential direction, e) that the magnetic sensor (6) optionally does not completely fill the annular space (9) in the radial direction, but leaves a free space (10) radially inside. [8] Rotary atomizer (1) according to one of the preceding claims, characterized by , a) that the annular space (9) is at least partially filled with an electrically insulating material, b) that the electrically insulating material in the annular space (9) is preferably plastic, c) that the electrically insulating material in the annular space (9) preferably has a specific electrical resistance which is greater than 10 3 Ω mm 2 / m, 10 4 Ω mm 2 / m, 10 5 Ω mm 2 / m, 10 6 Ω mm 2 / m, 10 7 Ω mm 2 / m, 10 8 Ω mm 2 / m. 10 9 Ω mm 2 / m or 10 10 Ω mm 2 / m. [9] Rotary atomizer (1) according to one of the preceding claims, characterized by a laminated core (12) with numerous laminations (13) to reduce eddy current losses caused by the circulating pole changes of the magnetic field (B→) of the rotating magnet (5, 11). [10] Rotary atomizer (1) according to claim 9, characterized by , a) that the magnetic sensor (6) is arranged at least partially in the laminated core (12), and / or b) that the magnetic sensor (6) is arranged in an axial bore (15) in the laminated core (12). [11] Rotary atomizer (1) according to claim 9 or 10, characterized by , a) that the individual sheets (13) of the laminated core (12) are each flat and each lie in a plane containing the axis of rotation (3), and / or b) that the individual sheets (13) are arranged distributed over the circumference with respect to the axis of rotation (3), and / or c) that the laminated core (12) is arranged in a ring shape and coaxially to the rotational axis (3) of the rotor (2, 5, 11), and / or d) that at least some of the sheets (13) of the laminated core (12) are slotted, and / or e) that the sheets (13) consist of a mu-metal, and / or f) that the adjacent sheets (13) of the laminated core (12) are each separated by an air gap (14), and / or g) that the laminated core (12) is preferably arranged within the detection range (8) around the magnet (5, 11). [12] Rotary atomizer (1) according to one of the preceding claims, characterized by , a) that the magnetic field generated by the rotating magnet (5, 11) as a useful signal (B→) has a first maximum magnetic field strength at the location of the magnetic sensor (6), b) that the counter magnetic field generated by the induction currents as an interference signal has a second maximum magnetic field strength at the location of the magnetic sensor (6), and c) that the second maximum magnetic field strength of the interference signal at the location of the magnetic sensor (6) is at most 30%, 20%, 10%, 5% or 2% of the first maximum magnetic field strength of the useful signal. [13] Rotary atomizer (1) according to one of the preceding claims, characterized by that the magnetic sensor (6) is elongated and is aligned with its longitudinal axis parallel to the rotation axis (3) of the rotor. [14] Rotary atomizer (1) according to claim 13, characterized by , a) that the magnetic sensor (6) is arranged proximally in front of the magnetic disc (5) in the axial direction and is separated from the magnetic disc (5) in the axial direction by the air gap (7), and / or b) that the magnetic field (B→) runs essentially axially in the air gap (7), and / or c) that the magnetic sensor (6) is arranged at least partially within the maximum diameter of the magnetic disc (5). [15] Rotary atomizer (1) according to claim 13, characterized by , a) that the magnetic sensor (6) at least partially overlaps with the magnetic disc (5) in the axial direction, and / or b) that the magnetic sensor (6) is arranged radially outside the magnetic disc (5) and is separated from the magnetic disc (5) in the radial direction by the annular air gap (7), and / or c) that the magnetic field (B→) in the air gap (7) runs substantially radially, and / or d) that the magnetic disc (6) is magnetized around its circumference. [16] Rotary atomizer (1) according to one of claims 1 to 12, characterized by that the magnetic sensor (6) is elongated and is aligned with its longitudinal axis radially with respect to the rotation axis (3) of the rotor. [17] Rotary atomizer (1) according to claim 16, characterized by , that a) that the magnetic sensor (6) is arranged on the circumference of the magnetic disc (5) radially outside the magnetic disc (5) and in axial overlap with the magnetic disc (5) and is separated from the magnetic disc (5) in the radial direction by the annular air gap (7), and / or b) that the magnetic field (B→) in the air gap (7) runs substantially radially, and / or c) that the magnetic disc (6) is magnetized around its circumference. [18] Rotary atomizer (1) according to claim 16, characterized by , that a) that the magnetic sensor (6) is arranged proximally in front of the magnetic disc (5) in the axial direction and is separated from the magnetic disc (5) in the axial direction by the air gap (7), and / or b) that the magnetic field (B→) in the air gap (7) runs essentially axially. [19] Rotary atomizer (1) according to one of the preceding claims, characterized by , a) that the magnetic sensor (6) is a Wiegand sensor (6), and / or b) that the rotor (2, 5, 11) has the magnetic sensor (6) as a separate component which is connected in a rotationally fixed manner to the rotor (2, 5, 11), and / or c) that the rotor (2, 5, 11) has an atomiser shaft (2) which has at its distal end a mounting option for a bell cup, in particular in the form of a screw thread for screwing the bell cup onto the atomiser shaft, and / or d) that the rotary atomizer (1) has a compressed air turbine to drive the rotor (2, 5, 11), and / or e) that the rotating magnet (5, 11) has several pairs of magnetic north poles (N) and magnetic south poles (S) alternating over its circumference, in particular more than two, three or four pairs, and / or f) that the detection range (8) around the magnet (5, 11) along the rotation axis (3) has an axial extension which is at most 5 cm, 3 cm, 2 cm, 1 cm and / or at least 1 mm, 2 mm, 3 mm, 4 mm or 5 mm, and / or g) that the detection range (8) around the magnet (5, 11) in the radial direction with respect to the rotation axis (3) has a radial extension which is at most 3 cm, 2 cm, 1 cm, 5 mm and / or at least 1 mm, 2 mm, 3 mm, 4 mm or 5 mm, and / or h) that the distribution of the magnetic poles (N, S) over the circumference of the rotor (2, 5, 11) is not rotationally symmetrical in order to be able to detect both the speed and the direction of rotation of the rotor (2, 5, 11), and / or i) that the magnetic sensor (6) can only detect the rotational speed within the detection range (8), but not outside the detection range (8). [20] Use of a rotary atomizer (1) according to one of the preceding claims for atomizing liquid or powder paint, in particular when painting motor vehicle body components.

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