Vacuum pump

Abstract

To provide a vacuum pump that operates as quietly as possible, the vacuum pump comprising: a stator; a rotor; a bearing unit having at least one electromagnetic bearing for supporting the rotor relative to the stator in a non-contact manner; at least one distance sensor configured to measure a distance between the rotor and the stator during operation; and a control unit configured to take countermeasures based on a distance measurement value provided from the distance sensor.SOLUTION: A vacuum pump 111 has at least one motion sensor 235, in particular an acceleration sensor or an angular velocity sensor. The motion sensor is configured to detect motion, in particular vibration, of the vacuum pump, and provide at least one motion measurement value based on the detected motion. A control unit 233 is further configured to take into account the motion measurement value provided by the motion sensor when taking countermeasures.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a vacuum pump, in particular a turbomolecular vacuum pump, comprising a stator, a rotor rotatable about a rotation axis relative to the stator, a bearing unit having at least one electromagnetic bearing supporting the rotor in a contactless manner relative to the stator, at least one distance sensor configured to measure the distance between the rotor and the stator during operation, and a control unit configured to take countermeasures based on distance measurements provided by the distance sensor. [Background technology]

[0002] Such vacuum pumps are basically known and are usually used to evacuate the recipient by means of a rotor that rotates during operation of the vacuum pump. During operation, the position of the rotor relative to the stator is regularly detected by means of a distance sensor and is permanently readjusted by a control unit connected to the distance sensor on the basis of the detected distance measurements. This can be done, for example, by appropriately energizing the coils of the electromagnetic bearing. The rotor is held at a distance relative to the stator by the electromagnetic attraction forces that are generated in the process. In principle, it is also conceivable to hold the rotor at a distance relative to the stator by means of electromagnetic repulsion forces. In this case, however, the electromagnetic forces act not only on the rotor but also on the remaining parts of the vacuum pump according to the reaction principle. This causes the entire vacuum pump to move. Furthermore, the motor used to drive the rotor also generates a force that drives the vacuum pump during operation of the vacuum pump.

[0003] Such movements of the vacuum pump, and in particular the vibrations caused thereby, can have a detrimental effect on the quiet operation of the vacuum pump and can be transmitted to the recipient connected to the vacuum pump, which is undesirable especially in vibration-sensitive applications, for example the movements of the vacuum pump can cause image disturbances in the case of electron microscopes. Summary of the Invention [Problem to be solved by the invention]

[0004] It is therefore an object of the present invention to provide a vacuum pump which operates as quietly as possible. [Means for solving the problem]

[0005] This problem is solved by a vacuum pump, a vacuum system and a method according to the independent claims.

[0006] The idea underlying the invention is to detect the movement of the vacuum pump or the movement caused by the vacuum pump by means of a movement sensor and, taking into account the detected movement, to take countermeasures to reduce the movement of the vacuum pump, thereby improving the quiet operation of the vacuum pump.

[0007] The movement detected by the movement sensor preferably relates to the movement of the vacuum pump as a whole, in particular not including the detection of the movement of individual moving parts of the vacuum pump, such as the rotor.

[0008] By detecting background motion when the vacuum pump is not in operation, in particular when the rotor is at rest, the motion sensor can distinguish between motion of the vacuum pump and background motion that is not caused by the vacuum pump itself. This can be done, for example, before or after the vacuum pump is turned on. Background motion, in particular periodic background motion, can be calculated from the totality of detected motions, thereby identifying the motion of the vacuum pump.

[0009] Preferably, the vacuum pump is a three-shaft, preferably five-shaft, vacuum pump in which the rotor is electromagnetically supported. In a three-shaft support, the rotor is electromagnetically supported both in the direction of its longitudinal or rotational axis and in the direction of two axes oriented perpendicular to each other and perpendicular to the longitudinal axis of the rotor in a first plane. In a five-shaft support, the rotor is additionally electromagnetically supported in the direction of two axes oriented perpendicular to each other and perpendicular to the longitudinal axis of the rotor in a second plane, the second plane being spaced apart in the direction of the longitudinal axis of the rotor in relation to the first plane. A five-shaft, rotor-supported vacuum pump is also referred to as a fully magnetically supported vacuum pump.

[0010] Preferably, the distance between the rotor and the stator in the direction of at least one of the bearing axes is monitored. At least one distance sensor can thus detect the axial distance between the rotor and the stator in a direction parallel to the rotor longitudinal axis. Additionally or alternatively, at least one distance sensor may be provided for detecting the radial distance between the rotor and the stator perpendicular to the rotor longitudinal axis. In particular, a radial distance sensor may be associated with each of two axes oriented orthogonally to the rotor longitudinal axis in one plane. A particularly accurate measurement of the radial rotor displacement can be achieved in that two distance sensors are respectively arranged on opposite sides of the rotor in each of two axes oriented orthogonally to the rotor longitudinal axis in one plane.

[0011] Preferably, two distance sensors for detecting radial distances are positioned spaced apart from each other in the direction of the rotor longitudinal axis, thereby detecting the tilt of the rotor.

[0012] Further advantageous configurations of the invention can be seen from the dependent claims, the description and the drawings.

[0013] The countermeasures taken by the control unit may consist in varying the rotational speed of the rotor, which makes it possible to avoid resonant frequencies that excite vibrations.

[0014] Additionally or alternatively, the countermeasure may consist in returning the rotor to a normal position or to a tolerance range which at least includes the normal position, the tolerance range being preferably determined by a preset or predefinable minimum tolerance distance value and a preset or predefinable maximum tolerance distance value.

[0015] Returning the rotor to its normal position or tolerance range can be achieved, for example, by a proper current flow through the coils of the bearing unit.

[0016] Preferably, the return of the rotor to the normal position is performed by minimizing the motion measurements. In other words, the rotor is brought to the normal position for particularly quiet operation by minimizing the motion values ​​measured by the motion sensors. When the rotor is in this position, only small or in the best case no restoring forces are required to hold the rotor in the normal position. This is noticeable in a reduction of the motion of the vacuum pump as a whole. Since the rotor rotates in the normal position for particularly quiet operation, this may also be referred to as rotor balancing.

[0017] The distance sensor can perform a monitoring function in the rotor balance described above. In particular, based on a comparison of the distance measurement currently measured by the distance sensor with a reference distance value representing the normal position, it is possible to recognize whether the rotor is approaching, moving away from or already in the normal position. When the rotor is in the normal position, the measured distance measurement and the reference distance value are identical.

[0018] The vacuum pump movement can be minimized in particular by repeatedly detecting the movement measurements and comparing the currently detected movement measurements with a predefinable maximum movement value. It may then be provided, if necessary, to repeatedly detect the measured distance values ​​and compare the detected distance measurements with a reference distance value representative of the rotor's normal position. One of the aforementioned countermeasures is taken, i.e. continued, until the movement measurements are smaller than the predefinable maximum movement value and / or the detected distance measurements are closer to the reference distance value than the previously detected distance measurements or until the detected distance measurements match the reference distance value.

[0019] Corresponding to the above-mentioned measures, the control unit basically tries to return the rotor to its normal position. In order to reduce the movements of the vacuum pump, the countermeasures may consist in, in particular, in allowing a stronger deviation of the rotor from its normal position within a tolerance range. In this case, the electromagnetic bearings, since their operation is relatively small, exert relatively small restoring forces on the rotor and the rest of the vacuum pump, in particular the housing, so that the movements of the vacuum pump as a whole are relatively small.

[0020] In this case, repeated detection of the motion measurement and comparison of the detected motion measurement with a predefinable maximum motion value may be performed in order to minimize the vacuum pump motion, with the countermeasures being continued until the detected motion measurement reaches or falls below the maximum motion value.

[0021] To protect the vacuum pump, repeated detection of distance measurements and comparison of the detected distance measurements with a minimum and / or maximum distance value may further be provided. If the minimum distance value is reached or falls below, or if the maximum distance value is reached or exceeded, countermeasures are taken solely on the basis of the distance value. The distance measurements are thus used to monitor whether the rotor is within an acceptable tolerance range. This avoids damage to the vacuum pump, for example due to a strong rotor displacement that would cause the rotor to come into contact with the stator. On the other hand, if the rotor is within the tolerance range, the introduction of countermeasures taking into account the distance value to minimize the movement is ignored.

[0022] To detect the vacuum pump motion, the motion sensor may be configured to detect the displacement magnitude and / or the direction of the motion, and thus the motion measurements may include the displacement magnitude and / or the direction of the motion.

[0023] Based on the detected direction of movement, the countermeasure may consist in inducing a movement of the vacuum pump in a direction opposite to the detected direction of movement by displacing the rotor. The induced opposite movement ideally has a displacement strength of the same magnitude as the detected movement strength. In general, the movement of the vacuum pump can be reduced or completely cancelled by the opposite movement based on the correct displacement of the rotor.

[0024] Advantageously, the control unit may generate a motion pattern, in particular a periodic motion pattern, based on the detected motion measurements and displace the rotor in such a way that the opposing motion generated by the precisely displaced rotor minimizes or completely cancels the motion of the vacuum pump by destructive interference, as in active noise cancellation.

[0025] Of course, the displacement of the rotors to produce motion in the opposite directions will be within acceptable tolerances.

[0026] To measure the vacuum pump motion, a motion sensor is preferably attached or attachable to the vacuum pump, in particular to any stator-side component of the vacuum pump, where the motion sensor may be attached or attachable inside, in particular in the vacuum area, or outside the vacuum pump.

[0027] A particularly suitable mounting location for the motion sensor is the connection point of the vacuum pump, by means of which the vacuum pump can be connected to another vacuum device, such as a recipient or another vacuum pump. Motion measurement at this point is particularly advantageous, since as little motion should be transmitted from here to another vacuum device as possible. An exemplary connection point of the vacuum pump is the inlet flange.

[0028] Additionally or alternatively, the motion sensor may be provided on a substrate, in particular on an existing substrate in the vacuum pump, such as a substrate supporting a control device of the vacuum pump. Preferably, an existing substrate may be retrofitted with the motion sensor. The substrate may be integrated into a vacuum feedthrough.

[0029] Preferably, a number of motion sensors are provided that are spaced apart from one another to detect the movement of the vacuum pump at various locations, the motion sensors being capable of measuring movement in the same or different directions.

[0030] As the motion sensor, any sensor from the group of known motion sensors may be used. According to one particularly simple and inexpensive realization, the motion sensor can detect the motion in one spatial direction. In order to detect the vacuum pump motion more comprehensively, the motion sensor can detect the motion in several spatial directions, in particular in three spatial directions oriented orthogonally to each other. The motion sensor may also include an inertial sensor, such as an acceleration sensor or an angular velocity sensor. In this case, the motion of the vacuum pump is obtained by integrating the acceleration measurements detected by the inertial sensor.

[0031] The motion sensor may be constructed as a micro-electromechanical system (MEMS) at low cost.

[0032] The invention also relates to a vacuum system comprising a vacuum pump as described above and a vacuum appliance, the vacuum pump being vacuum-technically connected to the vacuum appliance and a movement sensor being attached or attachable to the vacuum appliance, so that movements caused by the vacuum pump can be detected where they are to be avoided, i.e. in the vacuum appliance, for example a recipient to be evacuated or another vacuum pump, in particular of the type described above.

[0033] Thus, the movements of the vacuum pump can advantageously be minimized so that no or at most negligible movements occur in the vacuum equipment connected to the vacuum pump.

[0034] A motion sensor attached or attachable to another vacuum device may be provided in addition to or instead of a motion sensor attached or attachable to the vacuum pump.

[0035] The communication between the motion sensor and the control unit can be wired or wireless.

[0036] If the other vacuum equipment is a vacuum pump also having a rotor, then one or more motion sensors can be used to recognize resonance phenomena between the vacuum pumps and to suppress them by taking one of the countermeasures mentioned above, in particular by adapting at least one rotor rotation speed and / or reducing rotor vibrations by precisely controlling the electromagnetic bearings.

[0037] The invention further relates to a method for operating a vacuum pump as described above or for operating a vacuum system as described above.

[0038] The invention will now be described on the basis of exemplary advantageous embodiments with reference to the accompanying drawings, in which: FIG. [Brief description of the drawings]

[0039] [Figure 1] 1 shows a schematic perspective view of a turbomolecular vacuum pump known in the prior art; [Diagram 2] A schematic diagram showing a bottom view of the turbomolecular pump of FIG. [Diagram 3] 3 shows a schematic cross-sectional view of the turbomolecular vacuum pump along the section line AA shown in FIG. 2. [Figure 4] 3 shows a schematic cross-sectional view of the turbomolecular vacuum pump along the section line BB shown in FIG. 2; [Diagram 5] 3 shows a schematic cross-sectional view of the turbomolecular vacuum pump along the section line CC shown in FIG. 2; [Figure 6] 6 shows a schematic cross-sectional view of a turbomolecular vacuum pump according to one embodiment of the turbomolecular vacuum pump shown in FIGS. 1 to 5, together with a first attachment point for a motion sensor according to the present invention; FIG. [Figure 7] 7 shows a schematic cross-sectional view of the turbomolecular vacuum pump of FIG. 6 together with a second mounting point for a motion sensor according to the invention; [Figure 8] 7 shows a schematic cross-sectional view of the turbomolecular vacuum pump of FIG. 6 together with a third mounting point for a motion sensor according to the invention; [Figure 9] 7 shows a schematic cross-sectional view of the turbomolecular vacuum pump of FIG. 6 connected to a recipient, together with a fourth attachment point for a motion sensor according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] Since the known vacuum pump described in connection with Figures 1 to 5 is similar to the vacuum pump according to the invention shown in Figures 6 to 9, except for the rotor bearing, the characteristics described in connection with Figures 1 to 5 also apply in principle to the vacuum pump shown in Figures 6 to 9.

[0041] Fig. 1 shows a vacuum pump in the form of a turbomolecular vacuum pump 111, which will hereinafter also be referred to as turbomolecular pump 111 for short or simply vacuum pump 111. The turbomolecular pump 111 shown in Fig. 1 has a pump inlet 115 surrounded by an inlet flange 113, to which a recipient 225 may be connected in a manner known per se (Fig. 9). Gas coming from the recipient can be sucked from the recipient via the pump inlet 115 and pumped through the pump to a pump outlet 117, to which an auxiliary vacuum pump, for example a rotary vane pump, may be connected.

[0042] The inlet flange 113 forms the upper end of a housing 119 of the vacuum pump 111 in the orientation of the vacuum pump according to Fig. 1. The housing 119 has a lower part 121, on which an electronics housing 123 is arranged laterally. In the electronics housing 123, electrical and / or electronic components of the vacuum pump 111 are accommodated, for example for operating an electric motor 125 (see also Fig. 3) arranged in the vacuum pump. The electronics housing 123 is provided with a number of connections 127 for accessories. Furthermore, a data interface 129 (for example according to the RS485 standard) and a current supply connection 131 are arranged in the electronics housing 123.

[0043] There are also turbomolecular pumps that do not have this type of attached electronics housing, but are connected to external drive electronics.

[0044] A ventilation inlet 133, in particular in the form of a ventilation valve, is provided in the housing 119 of the turbomolecular pump 111. Via the ventilation inlet 133, the vacuum pump 111 can be vented. In the region of the lower part 121, a sealing gas connection 135 (also called purge gas connection) is also arranged. Via the sealing gas connection 135, a purge gas can be fed into a motor chamber 137 in order to protect the electric motor 125 (see, for example, FIG. 3) against the gas pumped by the pump. In the motor chamber 137, the vacuum pump 111 accommodates the electric motor 125. In the lower part 121, two coolant connections 139 are also arranged. In this case, one coolant connection is provided as an inlet for the coolant and the other coolant connection is provided as an exhaust. A coolant can be introduced into the vacuum pump for cooling purposes. The further turbomolecular vacuum pump present (not shown) is operated exclusively air-cooled.

[0045] The underside 141 of the vacuum pump can be used as a base, so that the vacuum pump 111 can be operated vertically with respect to the underside 141. Moreover, the vacuum pump 111 can be fixed to the recipient 225 via the inlet flange 113 and thus operated in a suspended state, so to speak (FIG. 9). Moreover, the vacuum pump 111 can be configured so that it can be operated even when oriented in a different direction than that shown in FIG. 1. Vacuum pump configurations are also feasible in which the underside 141 can be arranged not only facing downwards, but sideways or upwards. In this case, in principle, any angle is conceivable.

[0046] In particular, other turbomolecular vacuum pumps (not shown) that are present and are larger than the pump shown cannot be operated in a vertical position.

[0047] Various screws 143 are further arranged on the underside 141 shown in Fig. 2. By means of these screws 143, components of the vacuum pump, not specified in detail here, are fixed to one another. For example, a bearing cover 145 is fixed to the underside 141.

[0048] Fastening holes 147 are furthermore arranged in the underside 141. Via the fastening holes 147, the pump 111 can be fixed, for example, to a mounting surface. This is not possible with other existing turbomolecular vacuum pumps (not shown), in particular those larger than the pump shown.

[0049] 2 to 5 show a coolant line 148. In the coolant line 148 a coolant can be circulated which is introduced and discharged via the coolant connection 139.

[0050] As shown in the cross-sectional views of Figures 3 to 5, the vacuum pump has multiple process gas pumping stages for pumping process gas acting on a pump inlet 115 to a pump exhaust 117.

[0051] A rotor 149 is arranged within the housing 119. The rotor 149 has a rotor shaft 153 rotatable about a rotation axis 151, which in this case corresponds to a longitudinal axis 151 of the rotor 149. The terms rotation axis 151 and rotor longitudinal axis 151 are used synonymously below.

[0052] The turbomolecular pump 111 has a number of turbomolecular pump stages connected in series to provide a pumping action. The turbomolecular pump stages have a number of radially extending rotor blades 155 fixed to the rotor shaft 153 and a number of stator vanes 157 arranged between the rotor blades 155 and fixed within the housing 119. In this case, each of the rotor blades 155 and the adjacent stator vanes 157 forms one turbomolecular pump stage. The stator vanes 157 are held at a desired axial distance from each other by spacer rings 159.

[0053] The vacuum pump further comprises Holweck pump stages arranged radially inside and outside one another and connected in series to provide a pumping action. There are alternative turbomolecular vacuum pumps (not shown) that do not comprise Holweck pump stages.

[0054] The rotor of the Holweck pump stage comprises a rotor hub 161 arranged on the rotor shaft 153 and two Holweck rotor sleeves 163, 165 with cylindrical flanks fixed to and supported by the rotor hub 161. The Holweck rotor sleeves 163, 165 are oriented coaxially with respect to the axis of rotation 151 and engage one another radially. Two Holweck stator sleeves 167, 169 with cylindrical flanks are further provided. The Holweck stator sleeves 167, 169 are likewise oriented coaxially with respect to the axis of rotation 151 and engage one another radially.

[0055] The pumping surfaces of the Holweck pump stages are formed by the lateral surfaces, i.e. by the radially inner and / or outer surfaces of the Holweck rotor sleeves 163, 165 and the Holweck stator sleeves 167, 169. The radially inner surface of the outer Holweck stator sleeve 167 faces the radially outer surface of the outer Holweck rotor sleeve 163, forming a radial Holweck gap 171, and together with this outer surface forms the first Holweck pump stage following the turbomolecular pump. The radially inner surface of the outer Holweck rotor sleeve 163 faces the radially outer surface of the inner Holweck stator sleeve 169, forming a radial Holweck gap 173, and together with this outer surface forms the second Holweck pump stage. The radially inner surface of the inner Holweck stator sleeve 169 opposes the radially outer surface of the inner Holweck rotor sleeve 165 while forming a radial Holweck gap 175, and together with this outer surface forms the third Holweck pump stage.

[0056] The lower end of the Holweck rotor sleeve 163 may be provided with a radially extending channel, through which the radially outer Holweck gap 171 is connected to the central Holweck gap 173. The upper end of the inner Holweck stator sleeve 169 may be provided with a further radially extending channel, through which the central Holweck gap 173 is connected to the radially inner Holweck gap 175. In this way, the multiple mutually interlocking Holweck pump stages are connected in series with each other. The lower end of the radially inner Holweck rotor sleeve 165 may be further provided with a connecting channel 179 leading to the exhaust port 117.

[0057] The pumping surfaces of the Holweck stator sleeves 167, 169 each have a number of Holweck grooves extending in the axial direction and spiraling around the rotation axis 151, while the opposing sides of the Holweck rotor sleeves 163, 165 are smoothly formed and pump the gas for the operation of the vacuum pump 111 forward in the Holweck grooves.

[0058] For the rotatable support of the rotor shaft 153, a rolling bearing 181 is provided in the area of ​​the pump outlet 117 and a permanent magnetic bearing 183 is provided in the area of ​​the pump inlet 115.

[0059] In the region of the rolling bearing 181, the rotor shaft 153 is provided with a conical splash nut 185. The splash nut 185 has an outside diameter that increases towards the rolling bearing 181. The splash nut 185 is in sliding contact with at least one scraping member of the working medium reservoir. In other existing turbomolecular vacuum pumps (not shown), instead of a splash nut, a splash screw may be provided. Since various configurations are thereby possible, the term "splash tip" is also used in the above context.

[0060] The working medium reservoir comprises a number of absorbent discs 187 stacked one above the other, which are impregnated with a working medium for the rolling bearings 181, for example a lubricant.

[0061] During operation of the vacuum pump 111, the working medium is transferred by capillary action from the working medium reservoir via the scraping element to the rotating splash nut 185 and is then forced by centrifugal force along the splash nut 185 towards the increasing outer diameter of the splash nut 185 towards the rolling bearing 181, where it fulfills, for example, a lubrication function. The rolling bearing 181 and the working medium reservoir are enclosed in the vacuum pump by a trough-like insert 189 and a bearing cover 145.

[0062] The permanent magnetic bearing 183 has a rotor-side bearing half 191 and a stator-side bearing half 193. Each of these has a ring stack, which consists of several rings 195, 197 of permanent magnets stacked axially one above the other. The ring magnets 195, 197 face each other forming a radial bearing gap 199, with the rotor-side ring magnet 195 arranged radially outward and the stator-side ring magnet 197 arranged radially inward. The magnetic field present in the bearing gap 199 induces a magnetic repulsion between the ring magnets 195, 197. This repulsion provides a radial support for the rotor shaft 153. The rotor-side ring magnet 195 is supported by a support part 201 of the rotor shaft 153. The support part 201 surrounds the ring magnet 195 radially outward. The stator-side ring magnet 197 is supported by a support part 203 on the stator side. The support part 203 extends through the ring magnet 197 and is suspended on radial struts 205 of the housing 119. Parallel to the axis of rotation 151, the ring magnet 195 on the rotor side is fixed by a cover element 207 connected to the support part 201. The ring magnet 197 on the stator side is fixed in one direction parallel to the axis of rotation 151 by a fixing ring 209 connected to the support part 203 and a fixing ring 211 connected to the support part 203. Between the fixing ring 211 and the ring magnet 197, a disc spring 213 may further be provided.

[0063] An emergency or safety bearing 215 is provided in the magnetic bearing. During normal operation of the vacuum pump 111, the emergency or safety bearing 215 runs free without contact and only engages if the rotor 149 is displaced too far radially relative to the stator, thus forming a radial stop for the rotor 149, so that a collision between the rotor-side and stator-side structures is prevented. The safety bearing 215 is configured as a non-lubricated rolling bearing and forms a radial gap together with the rotor 149 and / or the stator. The gap ensures that the safety bearing 215 is not engaged during normal pump operation. The safety bearing 215 engages during radial displacement, which is dimensioned to be sufficiently large so that the safety bearing 215 is not engaged during normal operation of the vacuum pump and at the same time is sufficiently small so that a collision between the rotor-side and stator-side structures is prevented in all circumstances.

[0064] The vacuum pump 111 has an electric motor 125 which drives a rotor 149 in rotation. The armature of the electric motor 125 is formed by the rotor 149. A rotor shaft 153 of the rotor 149 extends through a motor stator 217. A permanent magnet assembly may be arranged radially outwardly or embedded in the portion of the rotor shaft 153 which extends through the motor stator 217. An intermediate chamber 219 is arranged between the motor stator 217 and the portion of the rotor 149 which extends through the motor stator 217, the intermediate chamber 219 having a radial motor gap. Through the motor gap, the motor stator 217 and the permanent magnet assembly may magnetically interact to transmit a driving torque.

[0065] The motor stator 217 is fixed in the housing in a motor chamber 137 provided for the electric motor 125. Via a seal gas connection 135, a seal gas (also called purge gas, which can be, for example, air or nitrogen) can reach the motor chamber 137. Via the seal gas, the electric motor 125 can be protected against process gases, for example against corrosive parts of the process gas. The motor chamber 137 can be evacuated via the pump outlet 117, i.e. a vacuum pressure acts in the motor chamber 137, which is realized at least approximately by an auxiliary vacuum pump connected to the pump outlet 117.

[0066] A so-called labyrinth seal 223, known per se, may furthermore be provided between the rotor hub 161 and the wall 221 which defines the motor chamber 137. This in particular achieves better sealing of the motor chamber 217 with respect to the radially outer Holweck pump stages.

[0067] In the following, a vacuum pump 111 (FIGS. 6 to 8) or a vacuum system (FIG. 9) comprising a vacuum pump 111 and a recipient 225 according to the invention will be described.

[0068] Unlike the vacuum pump 111 described in relation to Figures 1 to 5, the rotor 149 of the vacuum pump 111 shown in Figures 6 to 9 is supported in a non-contact manner not by a rolling bearing 181 and a permanent magnetic bearing 183, but by a number of electromagnetic bearings 229a, 229b, 220c which form a bearing unit 227.

[0069] More precisely, the rotor 149 of the vacuum pump 111 shown in Figures 6 to 9 is electromagnetically supported along five axes. A first electromagnetic bearing 229a is used to axially support the rotor 149 in the direction of the longitudinal axis 151 of the rotor 149. A second electromagnetic bearing 229b is used to support the rotor 149 in the radial direction in the direction of two axes oriented perpendicular to each other and perpendicular to the roller longitudinal axis 151 in a first plane E1. Additionally, a third electromagnetic bearing 229c is used to support the rotor 149 in the radial direction in the direction of two axes oriented perpendicular to each other and perpendicular to the roller longitudinal axis 151 in a second plane E2. As is clear based on Figures 6 to 9, the first plane E1 is located parallel to and spaced apart from the second plane E2 in the direction of the rotor longitudinal axis 151. As can further be seen with reference to Figures 6 to 9, the rotor longitudinal axis 151 or the axis of rotation 151 is oriented perpendicular to the two planes E1, E2.

[0070] The position and rotational speed of the rotor 149 is controlled by appropriately energizing the coils 231 of the electromagnetic bearings 229a, 229b, 229c. In particular, the electromagnetic bearings 229a, 229b, 229c hold the rotor 149 at a distance relative to the stator 150 by electromagnetic forces during operation of the vacuum pump 111.

[0071] The distance between rotor 149 and stator 150 is detected by a distance sensor, which is not further shown in the drawings. More precisely, the distance between rotor 149 and stator 150, i.e. the position of rotor 149 relative to stator 150, is regularly detected by the distance sensor during operation of vacuum pump 111 and is permanently readjusted on the basis of the distance measurements detected by the distance sensor by a control unit 233 connected to the distance sensor. In so doing, the electromagnetic forces acting on rotor 149 also act on the remaining parts of vacuum pump 11 according to the reaction principle and are measurable as an undesired movement of the vacuum pump outwards.

[0072] At least one motion sensor 235 is provided to measure the movement of the vacuum pump 111 and provides a motion measurement based on the detected movement of the vacuum pump 111 .

[0073] The motion sensor 235 is configured to detect, among other things, the magnitude of displacement and / or the direction of motion of the motion, such that the motion measurements include the magnitude of displacement and / or the direction of motion.

[0074] 6-9 show various advantageous mounting points for the motion sensor 235. FIG.

[0075] 6, the motion sensor 235 is mounted as close as possible to the rotor 149 on the stator side of the vacuum pump 111. By being close to the rotor 149, the motion sensor 235 can be particularly good at detecting motion caused by restoring forces.

[0076] 7, the motion sensor 235 is mounted on a board (not shown) located between the electronics housing 123 and the housing 119. In particular, this may be an existing board that electrically connects the controller 233, for example housed in the electronics housing 123, to the bearing unit 227. The board may be integrated into or configured as a vacuum feedthrough. Advantageously, the vacuum pump 111 can be retrofitted with the motion sensor 235 using an existing board.

[0077] Since the movement of the vacuum pump 111 towards another vacuum device, such as the recipient 225, is transmitted to the vacuum device at the connection point, it is particularly advantageous to detect the movement of the vacuum pump at this point, i.e. before the movement is transmitted to the vacuum device. Thus, in the embodiment shown in FIG. 8, the movement sensor 235 is attached to the inlet flange 113 of the vacuum pump 111.

[0078] Additionally, the motion sensor 235 may be attached or attachable to the recipient 225 in a vacuum system having the vacuum pump 111 and the recipient 225. Such an attachment of the motion sensor 235 is shown in FIG.

[0079] In all embodiments shown in Figures 6 to 9, the movement sensor 235 is communicatively connected to the control unit 233. More precisely, the movement sensor 235 provides the control unit 233 with movement measurements based on the detected movement. This is indicated diagrammatically in Figures 6 to 9 by an arrow pointing from the movement sensor 235 to the control unit 233.

[0080] Based on the motion measurements provided by the motion sensor 235 and the distance measurements provided by the distance sensor, the control unit 233 takes countermeasures to reduce the motion of the vacuum pump 111. This is shown diagrammatically in Figures 6 to 9 by the arrows starting near the control device 233 and ending near the bearings 229a, 229b, 229c.

[0081] For example, the countermeasure of the control unit 233 may consist in, for example, changing the rotational speed of the rotor 149. Additionally or alternatively, the control unit 233 may return the rotor 149 to a normal position in which it rotates quietly, or to a tolerance range that at least includes the normal position.

[0082] The movement minimization can be achieved, for example, by repeatedly detecting the movement measurements and comparing them with a predefinable maximum movement value. At the same time, the measured distance values ​​may additionally be detected repeatedly and compared with a reference distance value representing the normal position of the rotor 149. At least one of the countermeasures is taken, i.e. continued, until the movement measurements are smaller than the maximum movement value and / or the detected distance measurements are closer to the reference distance value than the previously detected distance measurements or optimally coincide with the reference distance value. In this way, the rotor 149 does not move away from its normal position as much as possible, so that little or optimally no restoring forces are required to return the rotor 149, which is noticeable in particular in a vacuum pump 111 with a quiet rotation, i.e. low movement, as a whole.

[0083] Alternatively to the above-described motion minimization, the motion of the vacuum pump 111 may be minimized by repeatedly detecting the motion measurements as in the above-described method and comparing them with a predefinable maximum motion value. However, unlike in the above-described method, the rotor 149 is not forced to return to its normal position. Rather, the control unit 233 allows a relatively large deviation of the rotor 149 from its normal position within a tolerance range between a minimum and a maximum allowable distance value. This results in a relatively small movement of the bearings 229a, 229b, 229c, which in turn results in smaller restoring forces acting on the rotor and the rest of the vacuum pump 111, in particular the housing 119 of the vacuum pump 111, and therefore a smaller motion of the vacuum pump 111 overall.

[0084] In this method, the distance sensor is used to monitor that the rotor does not deviate from the tolerance range. For this purpose, the distance measurement is repeatedly detected and compared with a minimum and / or a maximum distance value. If the rotor 149 is in danger of deviating from the tolerance range, i.e. when the minimum distance value is reached or falls below or the maximum distance value is reached or exceeded, countermeasures are taken exclusively based on the distance value. The countermeasures then consist in particular in returning the rotor 149 to its normal position again in order to protect the vacuum pump 111.

[0085] According to another advantageous embodiment, based on the detected direction of movement, the countermeasures may consist in inducing a movement of the vacuum pump 111 in the opposite direction to the detected direction of movement by a displacement of the rotor 149. The induced opposite movement ideally has a displacement strength of the same magnitude as the detected movement strength. Overall, in this case, the movement of the vacuum pump 111 can be reduced or completely counteracted by a reverse movement based on a precise displacement of the rotor 149. [Explanation of symbols]

[0086] 111 Turbomolecular pump 113 Intake flange 115 Pump Inlet 117 Pump exhaust port 119 Housing 121 Lower part 123 Electronics Housing 125 Electric Motor 127 Accessory connection 129 Data Interface 131 Current supply connection 133 Ventilation Intake 135 Seal gas connection 137 Motor Room 139 Coolant Connection 141 Bottom surface 143 Screw 145 Bearing cover 147 Fixed hole 148 Coolant Line 149 Rotor 150 stator 151 Rotation axis 153 rotor shaft 155 Moving blade 157 Stator blade 159 Spacer ring 161 rotor hub 163 Holbeck Rotor Sleeve 165 Holbeck Rotor Sleeve 167 Holbeck Sterling Sleeve 169 Holbeck Sterling Sleeve 171 Holbeck Gap 173 Holbeck Gap 175 Holbeck Gap 179 Connection Channels 181 Rolling bearings 183 Permanent magnet type magnetic bearing 185 Splash Nut 187 Disc 189 Insert 191 Rotor side bearing half 193 Stator side bearing half 195 Ring Magnet 197 Ring Magnet 199 Bearing clearance 201 Support part 203 Support part 205 Radial Struts 207 Cover Elements 209 Support Ring 211 Fixing ring 213 Disc spring 215 Emergency or safety bearings 217 Motor Stator 219 Intermediate Room 221 Wall 223 Labyrinth Seal 225 Recipient 227 Bearing Unit 229a, 229b, 229c Electromagnetic bearings 231 Coil 233 Control Unit 235 Motion Sensor

Claims

1. A vacuum pump (111), in particular a turbomolecular vacuum pump (111), comprising: A stator (150); a rotor (149) rotatable about a rotation axis (151) relative to the stator (150); a bearing unit (227) having at least one electromagnetic bearing (229a, 229b, 229c) that supports the rotor (149) in a non-contact manner relative to the stator (150); at least one distance sensor configured to measure a distance between the rotor (149) and the stator (150) during operation; a control unit (233) configured to take countermeasures based on distance measurements provided by the distance sensor, the vacuum pump (111) comprises at least one motion sensor (235), in particular an acceleration sensor or an angular velocity sensor, the motion sensor (235) being configured to detect a motion, in particular a vibration, of the vacuum pump (111) and to provide at least one motion measurement based on the detected motion, The control unit (233) is further configured to take into account the motion measurements provided by the motion sensor (235) when taking countermeasures.

2. 2. The vacuum pump (111) of claim 1, wherein one countermeasure consists in returning the rotor (149) to a normal position, whereby returning the rotor (149) to the normal position is performed by minimizing a motion measure.

3. 2. The vacuum pump (111) of claim 1, wherein one countermeasure consists in allowing deviation of the rotor from a normal position to reduce movement of the vacuum pump (111).

4. 2. The vacuum pump (111) of claim 1, wherein the motion measurements include a direction of motion of the vacuum pump, and one countermeasure is to cause a displacement of the rotor (149) to cause a motion of the vacuum pump (111) in a direction opposite to the detected direction of motion.

5. A vacuum pump (111) according to any one of claims 1 to 4, wherein one countermeasure consists in varying the rotational speed of the rotor (149).

6. 6. The vacuum pump (111) according to any one of the preceding claims, wherein the motion sensor (235) is attached or attachable to the vacuum pump (111), in particular at a connection point leading to other vacuum equipment.

7. 7. A vacuum system comprising a vacuum pump (111) and a vacuum device according to any one of claims 1 to 6, wherein the vacuum pump (111) is vacuum-technically connected to the vacuum device, and the motion sensor (235) is attached or attachable to the vacuum device.

8. A method for operating a vacuum pump (111), in particular according to any one of claims 1 to 6, or a vacuum system, in particular according to claim 7, comprising said vacuum pump (111) and a vacuum device, The vacuum pump (111) comprises a stator (150), a rotor (149) rotatable about a rotation axis (151), a bearing unit (227) having at least one electromagnetic bearing (229a, 229b, 229c) for supporting the rotor (149) in a non-contact manner relative to the stator (150), at least one distance sensor for measuring a distance between the rotor (149) and the stator (150) during operation, and a control unit (233); the vacuum pump (111) or the vacuum equipment has a motion sensor (235), in particular an acceleration sensor or an angular velocity sensor, by means of which a motion of the vacuum pump (111) or a motion of the vacuum equipment caused by the vacuum pump (111) is detected, The method is: - providing distance measurements by said distance sensor; - providing at least one movement measurement by said movement sensor (235); - taking countermeasures by said control unit (233) based on distance measurements and taking into account movement measurements.

9. The countermeasures are: - returning said rotor (149) to its normal position, and / or - varying the rotational speed of said rotor (149); The method of claim 8 , comprising:

10. - repeatedly detecting movement measurements; - comparing the detected movement measure with a configurable maximum movement value; and - continuing the countermeasures until the detected movement measurement reaches or falls below the maximum movement value; The method of claim 8 or 9, further comprising:

11. - repeatedly detecting distance measurements; - comparing the detected distance measurements with reference distance values ​​representative of the normal position of said rotor (149); and continuing the countermeasures until the detected distance measurement is closer to the reference distance value than the previously detected distance measurement or until the detected distance measurement matches the reference distance value; The method of claim 10 further comprising:

12. - repeatedly detecting distance measurements; - comparing the detected distance measurement with a minimum and / or maximum distance value, and - taking countermeasures based exclusively on the measured distance values ​​when a minimum distance value is reached or falls below the minimum distance value or when a maximum distance value is reached or exceeds the maximum distance value; The method of claim 10 further comprising:

13. - detecting the direction of movement using said movement sensor (235); and - displacing the rotor (149) so as to cause a movement of the vacuum pump (111) in a direction opposite to the detected direction of movement; The method of claim 8 , comprising:

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