JP7209054B2 - how to run a vacuum pump - Google Patents

Description

The present invention relates to a method of operating a vacuum pump and to a vacuum pump comprising a controller arranged to carry out such a method.

Many types of vacuum pumps, such as turbomolecular pumps and/or vacuum pumps with Siegbahn pump stages, have rotors with active magnetic bearings. Since active magnetic bearings are non-contact and lubrication-free, normal operation of such vacuum pumps with active magnetic bearings is almost wear-free and maintenance-free.

However, due to common operating loads, such as electrical, mechanical, thermal and/or electrochemical and/or corrosive effects, and/or mainly due to the pump medium and/or auxiliary medium and introduced from the ambient atmosphere. General component deterioration, due to build-up or blockage of material, acts to limit the useful life of vacuum pumps with active magnetic bearings.

Furthermore, all forms of operational trouble can limit the service life of vacuum pumps with active magnetic bearings. Such operating troubles are, for example, a loss of supply voltage or a shock or persistent mechanical external influence acting beyond the permissible range. These effects may result, for example, from earthquakes, collisions, vibrations, resonance events, or electric, magnetic or other high energy fields or radiation. Furthermore, operational troubles due to process influences can occur. Process influences cause sudden changes in the flow rate of the medium to be pumped and/or the auxiliary medium, for example during venting, venting or at process start or process stop. Such operating troubles can, in many cases, lead to overloading and/or failure of the active magnetic bearings of the vacuum pump.

In such cases of overload or failure of active magnetic bearings, a secondary mechanical bearing system is usually provided. The secondary mechanical bearing system engages only the rotor or corresponding stator of the vacuum pump in normal operation and only engages the rotor and stator when the active magnetic bearings are inoperative or in trouble. It does not form a positive mechanical contact, whereupon this contact still permits rotation of the rotor relative to the stator of the vacuum pump. During periods of overload or failure of the active magnetic bearing assembly, the secondary mechanical bearing system ensures emergency bearing support and adequate centering of the rotor within the stator. Secondary mechanical bearing systems are also commonly known as emergency bearings, safeguarding bearings, protection bearings, landing bearings, support bearings, contact bearings or safety bearings. That last term is used below. The operating state of the emergency bearing using one or more safety bearings is hereinafter referred to as safety bearing operation.

Safety bearings are usually hard-loaded on the side of or to the stator and are completely stopped during normal operation. Moreover, the safety bearings may be hard-loaded on the side of or on the rotor and rotate completely with the rotor during normal operation of the vacuum pump. In the above context, "completely stopped" and "completely co-rotating" respectively mean that all components of the safety bearing move substantially relative to each other during normal operation without the effect of loads on the bearing. and thus does not fulfill the role of the rotary bearing during normal operation.

Safety bearings for vacuum pumps are generally not designed for continuous operation. Rather, the service life of the safety bearing during operation is typically only minutes to hours. Therefore, safety bearings for vacuum pumps are said to be only "time durable". Even if the safety bearing is configured as a full ball bearing, the safety bearing does not have sufficient durability to operate continuously within the structural space provided. Furthermore, the operation of vacuum pumps with safety bearings has the requirement that the safety bearings be kept free of lubricants, or at least free of organic and/or volatile lubricants. Safety bearings are therefore operated without lubricant or are wetted, impregnated or soaked with small amounts of special inorganic dry lubricants such as graphite or molybdenum disulfide.

In known methods of operating vacuum pumps, on the one hand, attempts are made to delay or prevent the initiation of safety bearing operation or the failure of active magnetic bearings as much as possible by various measures. Then, in order to prevent potential later troubles, process limiting measures such as for example ventilation gas quantity limitation or ventilation gas quantity control should be carried out, for example by calibrating the working range of the safety bearing. operating conditions can be optimized by or by the identification of expected conditions.

On the other hand, in known methods of operating a vacuum pump, after the start of safety bearing operation or when an active magnetic bearing fails, for example by venting an auxiliary medium braking the rotor of the vacuum pump through the entire vacuum system, or by power regeneration, by electrical braking by direct short-circuiting of the vacuum pump motor, or by deriving the dynamic braking energy generated in the vacuum pump motor to a provided load resistance. It is set to return to normal operation or shut down as quickly as possible.

The object of the present invention is to ensure that the safety bearing operation, including the period from the uncontrolled onset of trouble with the vacuum pump until the vacuum pump resumes normal operation or begins to stop, causes as little wear as possible on the safety bearings. The object of the present invention is to provide a method for operating a vacuum pump configured as follows.

This task is solved by a method with the features of claim 1 .

The method is set up to operate a vacuum pump having a rotor, a stator, actively controlled magnetic bearings for the rotor, and safety bearings for the rotor. According to the method, first a set of operating settings for the vacuum pump is provided, the set of operating settings comprising at least one operating state of the vacuum pump to be achieved during a trouble event. Furthermore, a trouble event is detected, in which the rotor moves away from the spatial area set for the rotor with respect to the stator, causing wear on the safety bearings.

Based on detected trouble events, a wear increment for the safety bearing is estimated and the wear increment is added to a variable for total safety bearing wear. Based on the set of operational settings for the vacuum pump and based on variables for total wear of the safety bearings, it is finally determined whether to implement measures to stabilize the rotor.

The operating state of the vacuum pump to be achieved in the event of a trouble and included in the set of operating setpoints may, for example, be a stalled state of the rotor of the vacuum pump which is to be achieved as quickly as possible, or Conversely, the vacuum may be maintained by stabilizing the rotor to return to normal operation with rotation within a given spatial region. In addition, the set of operating settings may include other operating conditions between these extremes, namely between stopping the rotor and maintaining vacuum with the rotor stabilized.

Trouble events can be detected, for example, using at least one sensor. A sensor is configured to monitor the spatial orientation of the rotor. In particular, magnetic bearing position sensors can be used, where two pairs of such position sensors are arranged perpendicular to each other radially with respect to the axis of rotation of the rotor such that a single pair or A further pair of position sensors are arranged axially, ie along the axis of rotation of the rotor. Alternatively or additionally, a vibration sensor and/or an acceleration sensor may be used to detect vacuum pump trouble events.

Variables for wear increment and total wear of a safety bearing can be specifically quantified as a percentage of the allowable wear of the safety bearing, where the total allowable wear is based on empirical values is considered fully worn and must be replaced during maintenance of the vacuum pump. The measurements of the aforementioned sensors can be used to determine the wear increment, and the measurements may be assigned the wear increment based on a calibrated table. For example, magnetic bearing position sensor measurements may represent the duration and strength of contact between the rotor and the safety bearing, and the duration and strength of contact between the safety bearing and the rotor may be the total allowable wear. may be assigned to the wear increment as a percentage of

The means for stabilizing the rotor include, in particular, that the rotor is returned by means of active magnetic bearings to a set spatial position or target position, which remains in normal operation of the vacuum pump. and can be checked, for example, by a magnetic bearing position sensor. This new stabilization is also referred to as "restabilization" of the rotor, as the measure results in a new stabilization of the rotor that was already stabilized before the trouble event.

When judging or deciding whether or not to implement measures to stabilize the rotor, the method "intermediates" between a set of operating setpoints for the vacuum pump and a variable for the total wear of the safety bearings. is done. For example, if the operation of a vacuum pump is set to always maintain a vacuum, then if the variable for total wear of the safety bearings is below a predetermined threshold, the rotor will be stabilized during a trouble event. You can always do what you can to make it happen. Conversely, when the variable for total wear reaches this threshold, the measures to stabilize the rotor are not carried out, but instead the rotor is stopped so that the operational safety of the vacuum pump is not compromised. can be determined. Conversely, even if the operating condition to be achieved is a stop of the vacuum pump rotor, the total wear is calculated based on the expected wear increase during a full stop operation until the vacuum pump rotor stops. appears to increase excessively, it may be decided to first implement measures to stabilize the rotor.

Safety bearing wear can therefore be minimized by a "broker" between a set of operational settings and variables for total wear. This is because this intermediation achieves a compromise between normal operation with rotor stabilization and full shutdown operation of the rotor of the vacuum pump until shutdown. Based on minimizing the wear of the safety bearings, the period of time between needing replacement of the safety bearings during maintenance of the vacuum pump can be maximized.

Advantageous developments of the invention are described in the dependent claims, the description and the drawings.

The vacuum pump can be shut down when it is determined that the measures to stabilize the rotor are not to be performed. Without means for stabilizing the rotor, reliable operation of the vacuum pump can no longer be guaranteed. Thus, a shutdown of the vacuum pump or rotor to a stop is provided, although the total wear of the safety bearings is increased based on a full stop motion of the rotor. Moreover, the shutdown of the vacuum pump avoids possible damage to the vacuum pump outside the safety bearings, in the region of the pumping elements, such as stator discs and rotor discs.

According to one embodiment, it is additionally checked whether the means for stabilizing the rotor were successful. If the means for stabilizing the rotor have failed, after a predetermined waiting time it can be decided whether to perform a new means for stabilizing the rotor. Other wear increments may then be specified, which are added to the variables for the total safety bearing wear.

The decision to implement a new rotor stabilization measure can similarly be based on a set of operating settings for the vacuum pump and on variables for total safety bearing wear. Thus, if the means for stabilizing the rotor fails, the means are repeated iteratively in this embodiment, with the waiting time between stabilization attempts increasing with the number of iterations. Repeated attempts to stabilize the stator can further minimize wear on the safety bearings. This is because, in general, the stabilization of the rotor of the vacuum pump increases the probability that it will return to normal operation again without contacting the safety bearing.

This can be especially important when there is only a brief trouble event that initially prevents the rotor from stabilizing. After the trouble event ends, measures to stabilize the rotor may succeed with a much higher probability than during the trouble event. In doing so, it can be checked, in particular, whether the trouble event initially detected and assigned to the wear increment continues, ie during and/or after the means for stabilizing the rotor. Depending on this check, further, when the set of operating settings for the vacuum pump includes more than one operating state to be achieved, among the sets of operating settings for the vacuum pump: One operating state can be selected.

When judging or deciding whether to carry out a new measure for stabilizing the rotor, there is additionally a probability for a new stabilization of the rotor depending on the current speed of rotation of the rotor and/or other operating parameters of the vacuum pump. A characteristic map containing Characteristic maps may be empirically based as well.

In addition, the vacuum pump can be shut down and/or an error notification can be output when the variable for total safety bearing wear exceeds a predetermined threshold. The threshold may depend on the expected life of the safety bearing. The recording of the wear by means of variables for total wear thus makes it possible to ensure the timely replacement of potentially defective safety bearings.

Wear increment values may be estimated based on experimental data and/or empirical values. In this case, the estimation of the wear increment value is based on measurements of at least one sensor, determined in particular during a trouble event. Thereby, the value of the wear increment may depend on the strength of the trouble event as reflected in the sensor's experimental data, for example.

The wear increment value can also be estimated depending on the rotation speed of the rotor when the trouble event begins and/or depending on the installation attitude of the vacuum pump. In this case, the value of the wear increment can be in particular proportional to the square of the rotational speed of the rotor. Therefore, since the rotational energy of the rotor is also proportional to the square of the number of rotations of the rotor, the value of the wear increase amount can increase in proportion to the rotational energy of the rotor. Overall, therefore, depending on the speed of rotation of the rotor and the installation position of the vacuum pump, different evaluations of trouble events are made when wear is recorded.

According to another embodiment, the wear increment may comprise at least two parts. The first part of which may be based on the initial acceleration of the safety bearing when the trouble event begins, while the second part may be based on the rotor stalling during rotor stabilization or until the rotor stops. It may be based on expected safety bearing wear during operation. Furthermore, the amount of wear increase upon successful rotor stabilization may additionally include a third portion that may be based on the stopping action of the safety bearing after rotor stabilization. Each of the three portions can likewise have different values depending on the course of the means for stabilizing the rotor. Based on the three parts of the wear increment, the trouble event and its effect on the wear of the safety bearing can be evaluated in detail.

A set of operating settings for a vacuum pump may comprise at least two operating states of the vacuum pump to be achieved in the event of a trouble, these operating states being maintaining a vacuum within the vacuum pump and maintaining the vacuum pump. Including with shutdown. In this case, the operating conditions to be achieved in the event of a trouble can be prioritized by the user of the vacuum pump and/or by a learning algorithm. Thus, not only can at least two operating states to be achieved in the event of a trouble event be set, but these operating states can be dynamically evaluated by the user of the vacuum pump and/or by a learning algorithm, whereby preferably The operating state to be achieved is adapted to the respective operating mode of the vacuum pump or of the vacuum installation in which the vacuum pump is present.

According to another embodiment, the estimated wear increment for the safety bearings based on detected trouble events can be updated during the means of stabilizing the rotor or during shutdown of the vacuum pump. The updated wear increment may be added to the variable for total safety bearing wear in place of the previously estimated wear increment. An initial estimate of the wear increment is therefore adapted to the course of the means that cause the rotor to stabilize or the vacuum pump to shut down. This allows the actual wear of the safety bearing to be recorded in a more accurate manner by the variable for total wear.

According to yet another embodiment, the safety bearing may have multiple bearing points. According to the method, in this case, respective wear increments for each bearing location can be identified and added to each variable for total wear at each bearing location. Thus, in this embodiment, a more detailed record of the wear of the safety bearing per bearing location within the safety bearing is provided rather than for the safety bearing as a whole. A shutdown of the vacuum pump and/or an error notification can then be output when at least one of the variables for total wear at one of the bearing locations exceeds a predetermined threshold.

A further object of the invention is a vacuum pump comprising a rotor, a stator, an actively controlled magnetic bearing for supporting the rotor and a safety bearing for the rotor. The vacuum pump further comprises at least one means for detecting a trouble event, during which the rotor moves away from the spatial area set with respect to the stator with respect to the rotor, causing wear on the safety bearings. Furthermore, the vacuum pump comprises a controller and a memory, which contains variables for the total wear of the safety bearings. The controller is configured to carry out the method as described above.

Therefore, the advantages and disclosures mentioned above regarding the method and its embodiments according to the invention also reasonably apply to the vacuum pump according to the invention.

The memory containing the variables for the total wear of the safety bearing is therefore directly assigned to the safety bearing, i.e. the memory forms a unit with the safety bearing and the unit is used during maintenance of the vacuum pump. can be exchanged with The memory may be integrated in the safety bearing or may form a separate device, which on the other hand for example forms a unit spatially with the safety bearing. Moreover, in both cases the memory is a separate unit with respect to the control device by which the operation of the vacuum pump and in particular the magnetic bearings of the rotor is controlled, a separate unit with respect to the maintenance of the vacuum pump. , should be treated independently of the safety bearings and the memory of the total wear variables.

The memory can thus provide a record of the wear of the safety bearing, for example over the total service life of the safety bearing and independently of the rest of the control electronics of the vacuum pump. In this case, the memory only makes it possible to add the wear increment for the safety bearing to the variable for the total safety bearing wear, otherwise the variable for the total safety bearing wear becomes may be configured to remain unchanged in between.

At least one means for detecting a trouble event may comprise a sensor configured to obtain the spatial attitude of the rotor and/or a vibration sensor and/or an acceleration sensor attached to the stator. Such sensors can be used to provide early clues that a trouble event is about to begin. This applies in particular when the sensor is mounted as a vibration sensor and/or an acceleration sensor on the stator of the vacuum pump.

Furthermore, the vacuum pump may be a turbomolecular pump or a vacuum pump with Siegbahn pump stages, in which case the rotor is journalled by actively controlled magnetic bearings.

The invention will now be described on the basis of advantageous embodiments as examples with reference to the attached drawings.

1 schematically shows a turbomolecular pump in perspective view; FIG. 2 schematically shows the turbomolecular pump of FIG. 1 in a bottom view; FIG. 3 schematically shows a cross-sectional view of a turbomolecular pump along section line AA shown in FIG. 2; 3 schematically shows a cross-sectional view of a turbomolecular pump along section line BB shown in FIG. 2; 3 schematically shows a cross-sectional view of the turbomolecular pump along the section line CC shown in FIG. 2; 1 schematically shows a vacuum pump with actively controlled magnetic bearings; Fig. 4 schematically shows a radial sensor assembly; Fig. 3 schematically shows a flow chart of a method for operating a vacuum pump according to the invention;

The turbomolecular pump 111 shown in FIG. 1 has a pump inlet 115 surrounded by an inlet flange 113 . A recipient, not shown, can be connected to the pump inlet 115 in a manner known per se. Gases coming from the recipient can be drawn from the recipient via pump inlet 115 and pumped through the pump to pump outlet 117 . An auxiliary vacuum pump, such as a rotary vane pump, can be connected to the pump outlet 117 .

Inlet flange 113 forms the upper end of housing 119 of vacuum pump 111 in the vacuum pump orientation of FIG. Housing 119 has a lower portion 121 . An electronics housing 123 is arranged laterally in the lower part 121 . The electronics housing 123 accommodates the electrical and/or electronic components of the vacuum pump 111, for example for actuating an electric motor 125 arranged in the vacuum pump (see also FIG. 3). Electronics housing 123 is provided with a plurality of connections 127 for accessories. Furthermore, a data interface 129 (eg according to the RS485 standard) and a current supply connection 131 are arranged in the electronics housing 123 .

There are also turbomolecular pumps that are connected to external drive electronics without having an electronics housing of this kind attached.

The housing 119 of the turbomolecular pump 111 is provided with a vent inlet 133, particularly in the form of a vent valve. The vacuum pump 111 can be vented through the vent inlet 133 . A sealing gas connection 135 (also referred to as a purge gas connection) is additionally arranged in the region of the lower part 121 . Via seal gas connection 135, a purge gas is fed into motor chamber 137 to protect electric motor 125 (see, eg, FIG. 3) against gas being pumped by the pump. An electric motor 125 is housed in the vacuum pump 111 within the motor chamber 137 . Two coolant connections 139 are additionally arranged in the lower part 121 . In this case, one coolant connection is provided as an inlet for the coolant and the other coolant connection as an outlet. A coolant can be introduced into the vacuum pump for cooling purposes. Another turbomolecular vacuum pump present (not shown) is operated exclusively air-cooled.

Since the lower surface 141 of the vacuum pump can be used as a base, the vacuum pump 111 can be operated vertically with respect to the lower surface 141 . Moreover, the vacuum pump 111 may be fixed to the recipient via an inlet flange 113, so that it can be operated in a suspended state, so to speak. Further, vacuum pump 111 may be configured to operate when oriented in other orientations than shown in FIG. A vacuum pump configuration in which the lower surface 141 may be arranged sideways or upwards rather than downwards is also feasible. In this case, in principle, any angle can be realized.

Other existing turbomolecular vacuum pumps (not shown), which are in particular larger than the one shown, cannot be operated vertically.

Various screws 143 are further arranged on the underside 141 shown in FIG. By means of these screws 143 the components of the vacuum pump, not specified here in detail, are fixed together. For example, a bearing cover 145 is secured to the bottom surface 141 .

A fixing hole 147 is further arranged in the lower surface 141 . Via the fixing holes 147, the pump 111 can be fixed, for example, to an installation surface. This is not possible, especially with other existing turbomolecular vacuum pumps (not shown) which are larger than the one shown.

Coolant line 148 is shown in FIGS. In the coolant line 148 the coolant introduced and discharged via the coolant connection 139 can be circulated.

As shown in the cross-sectional views of FIGS. 3-5, the vacuum pump has multiple process gas pumping stages. The process gas pump stage is for pumping the process gas acting on the pump inlet 115 to the pump outlet 117 .

A rotor 149 is disposed within the housing 119 . Rotor 149 has a rotor shaft 153 rotatable about axis of rotation 151 .

The turbomolecular pump 111 has a plurality of turbomolecular pump stages connected together in series for pumping action. The turbomolecular pump stage has a plurality of radial rotor discs 155 fixed to the rotor shaft 153 and a stator disc 157 positioned between the rotor discs 155 and fixed within the housing 119 . In this case, one rotor disk 155 and one adjacent stator disk 157 each form a turbomolecular pump stage. The stator discs 157 are held at a desired axial distance from each other by spacer rings 159 .

The vacuum pump further comprises Holweck pump stages arranged radially in and out of each other and connected in series with each other to exert a pumping action. There are other turbomolecular vacuum pumps (not shown) that do not have Holweck pumping stages.

The rotor of the Holweck pump stage has a rotor hub 161 arranged on the rotor shaft 153 and two cylindrical-sided Holweck rotor sleeves 163 , 165 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 radially engage each other inwardly and outwardly. In addition, two Holweck stator sleeves 167, 169 are provided which are shaped like cylinders. The Holweck status sleeves 167, 169 are similarly oriented coaxially with respect to the axis of rotation 151 and radially engage each other inwardly and outwardly.

The pumping surfaces of the Holweck pump stages are formed by the lateral surfaces, namely 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. , forming 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 , forming the second Holweck pump stage. The radially inner surface of the inner Holweck stator sleeve 169 faces the radially outer surface of the inner Holweck rotor sleeve 165, forming a radial Holweck gap 175, and together with this outer surface. , forming the third Holweck pump stage.

The lower end of the Holweck rotor sleeve 163 may be provided with radially extending channels. Via channels, the radially outer Holweck gap 171 is connected to the central Holweck gap 173 . In addition, the upper end of the inner Holweck Stator sleeve 169 may be provided with radially extending channels. Via channels, the central Holweck gap 173 is connected to the radially inner Holweck gap 175 . Thereby, a plurality of Holweck pump stages that engage one another in and out are connected in series with one another. The lower end of the radially inner Holweck rotor sleeve 165 may further be provided with a connecting channel 179 leading to the air outlet 117 .

The pumping surfaces of the Holweck sleeves 167 , 169 each have a plurality of axially extending Holweck grooves spiraling around the axis of rotation 151 . On the other hand, the opposite sides of the Holweck rotor sleeves 163, 165 are smoothly formed and forward the gas for operation of the vacuum pump 111 in the Holweck grooves.

A roller bearing 181 is provided in the region of the pump outlet 117 and a permanent magnetic magnetic bearing 183 is provided in the region of the pump inlet 115 for the rotatable support of the rotor shaft 153 .

A conical splash nut 185 is provided on the rotor shaft 153 in the region of the rolling bearing 181 . Splash nut 185 has an outer diameter that increases toward rolling bearing 181 . Splash nut 185 is in sliding contact with at least one scraping member of the working medium reservoir. In another existing turbomolecular vacuum pump (not shown), instead of the splash nut, a splash screw may be provided. Since various configurations can be realized thereby, the term "splash tip" is also used in the above context.

The working medium reservoir has a plurality of absorbent discs 187 stacked one above the other. These discs 187 are impregnated with a working medium for the rolling bearing 181, for example a lubricant.

During operation of the vacuum pump 111, the working medium is transferred by capillary action from the working medium reservoir through the scraping member to the rotating splash nut 185 and, on the basis of centrifugal force, along the splash nut 185. , towards the increasing outer diameter of the splash nut 185 towards the rolling bearing 181 . There, for example, a lubricating function is fulfilled. The rolling bearing 181 and the working medium reservoir are enclosed in the vacuum pump by a trough-shaped insert 189 and a bearing cover 145 .

The permanent magnet magnetic bearing 183 has a rotor-side bearing half 191 and a stator-side bearing half 193 . These each have a ring stack consisting of a plurality of rings 195, 197 of permanent magnets axially stacked 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 radially outward and the stator side ring magnet 197 radially outward. placed on the inside. A magnetic field present in the bearing gap 199 causes a magnetic repulsion between the ring magnets 195,197. The repulsive force realizes radial bearing of the rotor shaft 153 . The rotor-side ring magnet 195 is supported by a support portion 201 of the rotor shaft 153 . The support portion 201 surrounds the ring magnet 195 radially outward. The stator-side ring magnet 197 is supported by the stator-side support portion 203 . Support portion 203 extends through ring magnet 197 and is suspended on radial struts 205 of housing 119 . Parallel to the axis of rotation 151 , a rotor-side ring magnet 195 is fixed by means of a cover element 207 connected to the support part 203 . The stator-side ring magnet 197 is fixed in one direction parallel to the rotation axis 151 by a fixing ring 209 connected to the support part 203 and a fixing ring 211 connected to the support part 203 . Further, a disc spring 213 may be provided between the fixed ring 211 and the ring magnet 197 .

An emergency or safety bearing 215 is provided within the magnetic bearing. The emergency or safety bearing 215 idles contactlessly during normal operation of the vacuum pump and engages only when the rotor 149 is excessively displaced radially relative to the stator, thereby providing rotor side A radial stop for the rotor 149 is formed so that the structure is prevented from colliding with the structure on the stator side. Safety bearing 215 is configured as a non-lubricated rolling bearing and forms a radial clearance with rotor 149 and/or stator. The clearance prevents the safety bearing 215 from engaging during normal pump operation. The radial displacement at which the safety bearing 215 engages is dimensioned sufficiently large so that it does not engage during normal operation of the vacuum pump and at the same time sufficiently small so that the structure on the rotor side and stator-side structures are prevented under all circumstances.

The vacuum pump 111 has an electric motor 125 that drives the rotor 149 to rotate. The armature of electric motor 125 is formed by rotor 149 . Rotor shaft 153 of rotor 149 extends through motor stator 217 . A permanent magnet assembly may be positioned radially outwardly or embedded in the portion of rotor shaft 153 that extends through motor stator 217 . An intermediate chamber 219 is positioned between the motor stator 217 and the portion of the rotor 149 that extends through the motor stator 217 . Intermediate 219 has radial motor clearance. Through the motor gap, the motor stator 217 and the permanent magnet assembly can magnetically interact to transmit drive torque.

The motor stator 217 is secured within the housing within a motor chamber 137 provided for the electric motor 125 . Via the seal gas connection 135 a seal gas (also called purge gas, which can be air or nitrogen, for example) can reach into the motor chamber 137 . Via the sealing gas, the electric motor 125 can be protected against process gases, eg corrosive parts of the process gas. Motor chamber 137 may also be evacuated via pump outlet 117 . Thus, the motor chamber 137 is at least approximately subjected to the vacuum provided by the auxiliary vacuum pump connected to the pump outlet 117 .

A so-called labyrinth seal 223 known per se may also be provided between the rotor hub 161 and the wall 221 defining the motor chamber 137 . This achieves in particular a better sealing of the motor chamber 217 with respect to the radially outwardly located Holweck pump stages.

The exemplary turbomolecular pump 111 described above and shown in FIGS. 1-5 has a passive permanent magnet magnetic bearing 183 and a safety bearing 215 . The method according to the invention, an example of which is shown in FIG. 8, relates to a vacuum pump with active magnetic bearings or actively controlled magnetic bearings in the rotor, to which for example the safety bearing 215 (see FIG. 3) ), FIG. 6 additionally shows such a vacuum pump 10 with active magnetic bearings, which will be explained below. . This vacuum pump 10 may include all the features of the vacuum pump 111 described above, with the exception of the components for journaling the rotor 149 .

FIG. 6 shows the vacuum pump 10 in a highly simplified schematic diagram. The vacuum pump 10 has a rotor 12 which supports a plurality of turborotor discs 14 and is rotatable about a rotor axis 18 by a motor 16 so that the stator discs (not shown) are driven. A turbo rotor disk 14 rotating relative to it produces a pumping action. In FIG. 6, the pumping action proceeds from top to bottom.

The rotor 12 is supported by a plurality of magnetic bearings. A first radial bearing 20 for the rotor 12 is arranged at the end of the rotor 12 on the exhaust side. A thrust bearing 22 is arranged at the same rotor end. A second radial bearing 24 is arranged at the end of the rotor 12 on the intake port side.

The first radial bearing 20 and the thrust bearing 22 are of actively controlled design. In essence, these bearings can actively oppose radial or axial displacement of the rotor 12 from its ideal position, eg, via electromagnets. For this purpose, a radial sensor assembly 26 is arranged beside the radial bearing 20, with which the radial sensor assembly 26 detects, in two spatial directions perpendicular to the rotor axis 16, the rotor 12 in a first axial region. Radial displacement can be measured. A thrust sensor assembly is also provided, but is not shown here for simplicity.

The second radial bearing 24 is designed passively, ie has no actuators that influence the rotor 12 . Rather, the second radial bearing 24 has a plurality of permanent magnets, for example on the rotor side and the stator side.

A second radial sensor assembly 28 is provided by which displacement of the rotor 12 in a second axial region can be measured. In this embodiment, a second radial sensor assembly 28 is positioned between the first radial bearing 20 and the second radial bearing 24 as well as between the motor 16 and the second radial bearing 24 . there is To that end, the second radial sensor assembly 28 is secured to a component 30 defining a motor chamber 32 of the motor 16 .

The first radial sensor assembly 26 and the second radial sensor assembly 28 are axially separated from each other by a large distance. If these radial sensor assemblies measure different displacements of the rotor 12 in corresponding axial regions, the rotor 12 is tilted, i.e. the rotor axis 18 of the rotor 12 is ideal, which may also be referred to as the zero axis. can be assumed to be non-parallel to the rotor axis. As soon as a tilt is recognized, the active first radial bearing 20 can counteract it. To that end, the first radial bearing 20 can, for example, impact the rotor 12 in order to push the rotor 12 back to its upright position to some extent. This type of control is comparable to that of an inverted pendulum. When the upper region of the rotor 12 begins to tip, a shock is introduced into the rotor 12 on the underside, which counteracts the tipping and in the best case causes the rotor 12 to move directly or gradually into its upright position. , the rotor axis 18 is parallel to the zero axis. Moreover, for example, at the same time not only the tilt is controlled, but also the radial position of the rotor 12 as well. Tilt control and position control are in particular superimposed on each other.

To avoid contact between the rotor 12 and the stator, not shown, in the event of failure of the active magnetic bearings, for example, the radial bearings 20, 24 and the thrust bearing 22 are provided with safety bearings, not shown, for example in FIG. Each is provided with a safety bearing 215 as shown.

An exemplary radial sensor assembly 34 is shown in FIG. One or both of the first and second radial sensor assemblies 26, 28 may be configured accordingly.

Radial sensor assembly 34 has a ring-shaped board 36 with a plurality of coils 38 mounted thereon. The rotor whose displacement is to be measured extends through this ring and its rotor axis should extend perpendicular to the drawing plane. If the rotor is displaced, i.e. sliding along the drawing plane in FIG. 7, this changes the induced voltage in the coil 38 and causes a change in the measurement signal. The displacement can thus be inferred from this measurement signal. In this case, two coils are provided on opposite sides in each movement direction x, y.

For vacuum pumps, such as for example the vacuum pumps 10, 111 shown in FIGS. 1 to 6, in principle various bearing configurations with different aspects and arrangements of the active magnetic bearings are possible. A 5-axis active magnetic bearing can be implemented, which has full active control and contactless journaling of the rotor 12, 149 except for the axis of rotation. Furthermore, permanent magnet magnetic bearings in which one or two bearing axes and/or one axial or one of the two radial two-axis bearing planes act passively rather than actively , and may consist of a contact point plain bearing or of a rolling bearing, for example a ball bearing. Passively acting permanent magnet magnetic bearings typically also have a safety bearing (see safety bearing 215 in FIG. 3), whereas they do not have contact plain or rolling bearings. There are many things. In the following, the term "safety bearing" always means all possible different possible configurations of safety bearings acting on a single, three, four or five axes.

The safety bearings 215 of the vacuum pumps 10, 111 have a plurality of spatially separated bearing points. The bearing locations are configured as single row full ball bearings or as pairs, i.e. full ball bearing pairs in an O- or X-arrangement which are aligned or selected relative to each other with a minimum bearing clearance. there is Single-row ball bearings are used, inter alia, for purely radially acting bearing locations. When the requirements for durability and/or low bearing loads of the safety bearing 215 are low, single row ball bearings are preferred for purely axial bearing locations or bearing locations with combined radial and axial action. can also be used. The high demands on axial bearing locations or bearing locations with combined radial and axial action can be met by the use of matched ball bearing pairs.

The components of ball bearings are made of various materials. The inner and outer rings of ball bearings are made of steel, special steel or special high grade tempered steel for use in rolling bearings. The rolling elements may likewise consist of special high grade tempered steel or ceramic materials. The optionally present bearing cage may likewise consist of a special high-grade tempered steel or a wear-resistant plastic with self-lubricating properties, with or without a fiber content to improve strength. . In all cases, the steel components may be hardened in parts or by parts, completely or intensively on individual surfaces, by various types of heat treatments.

Full ball bearings do not have guide elements for the rolling elements, such as bearing cages or other forms of rolling element spacers. Ball bearings are loaded with as many balls as possible. A special loading notch in the bearing ring wall can assist the ball loading operation. The higher the number of possible rolling elements for the design with bearing cage, the higher the absolute load capacity of the bearing can be achieved for a given design size. Furthermore, bearing cages are usually not robust enough to withstand high accelerations of the bearings without failure during use.

The safety bearing 215 is rigidly clamped at or to the stator and is completely stopped during normal operation of the vacuum pump 10,111. Moreover, the safety bearing 215 may alternatively be hard-fastened on the side of or to the rotor 149 and can rotate completely with the rotor 149 during normal operation of the vacuum pump 10,111. "Complete stop" and "Complete co-rotation" respectively mean that all components of the safety bearing 215 are in relative motion relative to each other during normal operation of the vacuum pumps 10, 111 and in the absence of bearing loads. means that you rarely do

Whether the safety bearing 215 is tightened on the rotor side or on the stator side, the other freely rotatable half of the safety bearing 215 is arranged with a gap to the other side. , contact is formed between the safety bearing 215 and the contact surfaces on the stator only when the rotor 12, 149 is displaced beyond what is typical in normal operation of active magnetic bearings, thus displacing the mechanical An emergency bearing is formed which limits the Only during safety bearing operation does rotation between the inner and outer races of the safety bearing 215 occur, which causes wear of the safety bearing 215 . The play that remains between the contact surfaces is called safety bearing play. Safe bearing play is usually regarded as the absolute overall play of the system within one motion axis or one motion plane. In a radial bearing this is the absolute difference between the diameters of the two contact surfaces and not the difference between the two radii, this is the actual circumferential direction acting around the contact surfaces on average during normal operation. will represent the absolute gap size of This likewise applies to thrust bearings where there is a corresponding linear dimension between the contact surfaces.

During operation of the active magnetic bearings 20, 22, parasitic entrainment can cause the freely rotatable half of the safety bearing 215 to automatically start rotating with the freely spaced counterpart of the safety bearing 215. There is Parasitic entrainment can be caused, for example, by electromagnetic interactions between the halves of the safety bearing 215, or in narrow gaps when the speed or speed difference between the halves of the safety bearing 215 is very large. Caused by gas friction. In the case of a safety bearing 215 fixed to and rotating with the rotor 12, 149, the parasitic entrainment would be reversed and the free rotatable half of the safety bearing 215 would be Looking at it, it appears to be stopped on the stator side.

This is accompanied by unnecessary wear of the safety bearings 215 as the undesired co-rotation continues to occur. To counteract this unwanted wear, the freely rotatable half of the safety bearing 215 is acted upon such that undesired co-rotation is inhibited or substantially prevented. This action can be effected, for example, by mechanically contacting, electromagnetically acting damping elements, or by unique bearings, for example clamp-mounted rolling elements or intentionally non-circularly constructed or imperfect bearing elements. done by configuration.

Unlike undesired co-rotation, in the event of magnetic bearing trouble or failure, a displacement of the rotor 12, 149 beyond a predetermined range of motion will occur. This displacement is spatially limited by the contact between the freely rotatable half of the safety bearing 215 and the counterpart. The sliding and static friction effects result in a very rapid and almost complete equalization of the rotational speeds of the free-running half of the safety bearing 215 and its counterpart. The resulting emergency bearing prevents extensive damage to the vacuum pump 10, 111 due to unwanted contact between the rotor and stator elements. The vacuum pumps 10, 111 are in safe bearing operation.

Depending on the type of trouble, safe-bearing operation is terminated by restarting the active magnetic bearings, or the pump maintains safe-bearing operation until the rotor 12, 149 stops. Restarting an active magnetic bearing is also referred to as restarting, restarting or restabilizing. The process of stopping, decelerating or slowing down the rotor 12, 149 during safety bearing operation, and in particular from the operating speed of the vacuum pump 10, 111 to stationary, is generally referred to as full stop operation. be done. When re-stabilization occurs during safety bearing operation before the rotor 12, 149 comes to a stop, this is referred to as a partial stop operation with specified initial and final speeds. A partial stop operation takes place, for example, from the operating speed of the vacuum pumps 10, 111 to a restabilization speed which is lower than, but substantially the same as, the operating speed. All these processes involve periods of varying length between the start and end of safety-bearing motion, also referred to as runtime in safety-bearing motion.

The type of trouble is detected by observation of additional sensors at the surface of the vacuum pump 10, 111, inside the vacuum pump 10, 111 or in the vicinity of the vacuum pump 10, 111, e.g. can be determined in detail by one or more vibration sensors and/or acceleration sensors. When a trouble event is detected in the stator of the vacuum pump 10,111 using such a sensor, the beginning of the trouble is the position signal of the radial sensor assembly 26,28 relative to the rotor 12,149 in the active magnetic bearing. It can be recognized earlier than by monitoring alone. Mechanical troubles are usually either equipment-side or stator-side and result in spatial stator displacements. As displacement begins, the rotor 12, 149 follows the stator with a position lag due to the active magnetic bearings as a stabilized gyro. A rapid, full-circumference recognition of the externally acting accelerations and motions of the stator can be used by active magnetic bearings, on the one hand, to optimize bearing control. On the other hand, this knowledge makes it possible to predict the safety bearing wear that will occur and the duration of the trouble.

A possible cause for trouble with magnetic bearings is loss of supply voltage. In this case, safe bearing operation can be avoided or delayed in various ways. On the one hand, the vacuum pump 10, 111 or the active magnetic bearing element or control may include an energy storage, e.g. It may have a battery and/or an accumulator and/or a capacitor. On the other hand, the drives provided in the vacuum pumps 10, 111 may be configured not only to be able to drive, but also to generate electricity. Rotational energy is thereby converted back into electrical energy, which in turn enables the emergency supply of active magnetic bearings.

If one safety means or a combination of various such safety means exists, the safety bearing will not operate until the last safety means fails. However, since the rotor 12, 149 cannot be driven any further upon loss of supply voltage, the rotor 12, 149 is either actively journaled free or dynamically braked to stop motion until it stops. Such stopping motion of the rotors 12, 149 may last from a few seconds to several hours, depending on the quality and maintenance of the vacuum within the vacuum pumps 10, 111 and configuration caused by, for example, eddy currents and magnetic reversal losses. It depends on the degree of electromagnetic losses of the element, the energy consumption of the active magnetic bearings and the optional active damping with additional load resistance. Safe bearing operation is introduced when all safety means for maintaining the voltage supply of the active magnetic bearing fail before the rotor 12, 149 stops. This generally results in partial re-stabilization without the possibility of attempting to re-stabilize to medium to low speeds of less than 15% to 20% of the final speed until the rotor 12, 149 comes to a stop. It is performed as a stop action.

The wear of the safety bearing 215 that occurs during safety bearing operation depends on a number of factors, of which the operating time and number of revolutions of the rotor 12, 149 during safety bearing operation constitute the major influencing factors. Another influencing factor is the relative velocity between the freely rotatable half of the safety bearing and its counterpart at the start of the safety bearing motion, i.e. at the moment of contact of the safety bearing halves. . This is because, at the moment of contact, an immediate and sudden acceleration of the safety bearing takes place. During extremely short periods of acceleration, the free-rotating half of the safety bearing 215 and its counterpart together with the rotor 12,149 are in a chaotic and unstable phase of operation.

For significant simplification, this operating phase can be divided into a number of steps. First, the contact partner entrains the free-running ring of the safety bearing 215 , which then entrains the rolling elements of the safety bearing 215 . Meanwhile, the respective relative movement with sliding friction is established between all the elements: the counterpart, the free-running ring of the safety bearing, the rolling elements of the safety bearing 215 and the fixed ring of the safety bearing 215. takes place between Following this, all elements reach a stable operating state. In this operating state, a largely non-chaotic rolling of the elements and thus their intended functioning takes place. Various frictional conditions, peel forces and load capacity load peaks occur during short-term chaotic operating conditions between elements within the safety bearing as well as between the safety bearing and its counterpart. The load capacity is higher the higher the acceleration that occurs.

Even after reaching a stable operating state of safety bearing operation, some chaotic behavior remains. This is because the rotor 12, 149 is free to move within the safety bearing play that necessarily exists during safety bearing operation, and can displace its position within the safety bearing 215 or its point of contact at any time. is. This is typically done by the various natural modes of motion and gyroscopic forces of the rotor 12,149, as well as the safety bearing 215 and rotor 12,149 relative to the geometric, e.g., inertial, main axis of the rotor 12,149. It is also the result of the mechanical axis of rotation being displaced by the safety bearing play during safety bearing operation of the system consisting of. within the range of motion of the safety bearing play, randomly, depending on the configuration and/or installation orientation of the vacuum pump 10, 111, i.e. depending on the position of the center of gravity of the rotor 12, 149 relative to the safety bearing position, and/or Depending on the spatial orientation of the rotor 12, 149 with respect to gravity, there will be varying frequencies of tilting, rocking or generally chaotic random displacement of the rotor within the safety bearing 215 .

The safety bearing play causes, depending on the configuration and/or installation orientation of the vacuum pump 10, 111, the free-running half of the safety bearing 215 and its counterpart to temporarily or permanently Mutual rolling is also caused. In the field of rotary bearing technology, this phenomenon is known when the bearing point is designed incorrectly. There, such a configuration is referred to as a rotating shaft with a clearance fit in the inner ring and a circumferential load. In this case, the number of rotations of the free-running ring or free-running half of the safety bearing 215 does not match the number of rotations of the rotor 12, 149 and deviates slightly. This is because the rolling relative to each other exerts an additional transmission ratio.

In addition, elastic deformation of the safety bearing 215, rotor 12, 149 and stator due to high operating loads during all phases of safety bearing operation can also occur as an additional influencing factor and enhance the various effects described above. The natural frequency of such deformations should be chosen such that the deformations do not cause resonance and thus damage to the vacuum pump 10, 111 components. Dynamically induced deformations may also lead to unexpected and undesired points of contact between the rotor 12, 149 and stator in some cases, which are subject to purely static tolerances in a series of dimensions. , in any case they have sufficient play or spacing with respect to each other, but in the dynamic case they can form contact points and lead to damage to the components of the vacuum pump 10, 111. .

Since the safety bearing 215 is not designed to operate continuously, and the service life of the safety bearing 215 during safety bearing operation is typically only minutes to hours, safety bearing operation is possible. should be maintained for the shortest possible time. Any safety bearing operation results in wear of the safety bearing 215 not only between the contact surfaces but also within the safety bearing 215 between the individual elements, namely the rolling elements and the inner and outer rings. In the extreme case, the vacuum pump 10, 111 is no longer operable after a severe trouble event already associated with safety bearing operation and must be repaired during the next start-up.

FIG. 8 shows an operating vacuum pump 10, 111 (see FIGS. 1-6) having actively controlled magnetic bearings 20, 22 supporting rotors 12, 149 and corresponding safety bearings 215. 1 shows a schematic block diagram of the method according to the invention, set up as follows. The method may also be used in other vacuum pumps with actively controlled magnetic bearings and safety bearings. For example, the method may be used in a vacuum pump with Siegbahn pump stages.

Method 300 begins at 301 by detecting a trouble event. During a trouble event, the rotor 12, 149 moves out of the spatial extent set for the rotor 12, 149 relative to the stator in normal operation. Trouble events are detected by magnetic bearing position sensors 26, 28, for example. Magnetic bearing position sensors 26 , 28 obtain the radial and axial position of rotor 12 , 149 .

A trouble event can cause wear to the safety bearing 215 . Thus, at 310, the method estimates a wear increment 315-1 assigned to the detected trouble event. The estimated wear increment 315 can be estimated based on measurement data from the magnetic bearing position sensors 26, 28, for example. The magnetic bearing position sensors 26,28 indicate how far the rotor 12,149 has deviated from its set position for this normal operation. Wear increment 315-1 is estimated based on these measurement data and empirical values assigned to these measurements.

Wear increment 315 - 1 is then transmitted to memory 320 . The memory 320 has a variable for the total wear of the safety bearing 215 and is therefore set to record the wear of the safety bearing 215 . Therefore, the memory 320 belongs to the vacuum pump 10, 111 and may be arranged beside the safety bearing 215 (see FIG. 3).

Wear increment 315 - 1 is added or added to variable 325 for total safety bearing 215 wear. A variable 325 for the total wear of the safety bearings 215 is initialized at zero when the vacuum pump 10, 111 is installed or started. Variables 325 for wear increment 315 - 1 and total safety bearing 215 wear are each expressed as a percentage of the maximum allowable wear of safety bearing 215 . At maximum allowable wear, maintenance of the vacuum pumps 10, 111 with replacement of the safety bearings 215 is required. In other words, variables 325 for wear increment 315 - 1 and total wear of safety bearing 215 each relate to a percentage of the total life of safety bearing 215 .

The method further provides a set 330 of operating settings for the vacuum pumps 10,111. The set of operating settings 330 includes the operating conditions of the vacuum pump 10, 111 to be achieved upon occurrence of the trouble event detected at 310. FIG. Operating states to be achieved are, for example, "make sure the vacuum is maintained" and "stop the rotor of the turbomolecular pump as quickly as possible". Moreover, the set of operating settings 330 for the vacuum pumps 10, 111 should be classified between "extreme conditions", i. It may include other operating states of the pump 10, 111 to be achieved.

At 340, the controller of the vacuum pump 10, 111, housed within the electronics housing 123 (see FIGS. 1-3), informs that a trouble event has been detected with the rotor 12, 149 of the vacuum pump 10, 111. is obtained from step 310 . Additionally, the controller obtains a variable 325 for the total safety bearing 215 wear from the memory 320 and a set 330 of operating settings for the vacuum pumps 10, 111 at 340 . At 340 , there is also a “brokerage” between the variable 325 for the total safety bearing 215 wear and the set 330 of operating set points for the vacuum pumps 10 , 111 . Specifically, based on the value of variable 325 for the total wear of safety bearing 215, which set 330 of operational settings should be implemented, i.e., which set 330 of operational conditions have been achieved for the existing trouble event. to be determined. Based on the selected operating conditions to be achieved, it is further determined at 350 whether to implement measures to stabilize the rotor 12,149. Such means include the rotors 12, 149 being returned to their predetermined spatial positions for normal operation of the vacuum pumps 10, 111 again by means of active magnetic bearings.

If it is determined at 350 that the measures to stabilize the rotor 12, 149 should not be performed, the vacuum pump 10, 111 is shut down at 360, with a full stop operation of the rotor 12, 149 until it stops. is done. Another wear increment 315-2 is identified at 360 for full stop operation of the rotor 12,149. Another wear increment 315-2 depends on the number of rotations of the rotor at the start of the dead stop operation and empirical values for wear during the dead stop operation. The wear increment for full stop operation 315-2 is transmitted to memory 320 and added to variable 325 for total safety bearing 215 wear in place of estimated wear increment 315-1. Therefore, the estimated wear increment 315-1 is updated by the wear increment 315-2 identified for the complete shutdown, where, for example, the wear increment 315-2 and the wear increment 315-1 The difference between is added to the variable 325 for total safety bearing 215 wear.

At 350, if it is determined that measures to stabilize the rotor 12, 149 are to be performed, the measures are actually performed. Therefore, the measures should result in the aforementioned "restabilization" of rotors 12, 149 that were stable prior to the trouble event detected at 310. At 370 it is checked whether the means of stabilizing or restabilizing the rotor 12, 149 were successful. When applicable, the vacuum pumps 10, 111 are returned to normal operation at 380, as the rotors 12, 149 are again in the desired spatial position for normal operation.

If it is determined at 370 that stabilization of rotor 12, 149 was not successful, then at 390 it is determined whether the means to stabilize rotor 12, 149 should be performed again before the method returns to 340. for a specific waiting time. Concurrently, at 390, an updated wear increment 315-3 is identified. The updated wear increment 315-3 is assigned to the attempt to stabilize the failed rotor 12,149. Similar to wear increment 315-2, updated wear increment 315-3 is added to variable 325 for total vacuum pump 10, 111 wear instead of estimated wear increment 315-1. At that time, likewise only the difference between the wear increment 315-3 and the wear increment 315-1 is used later, ie the estimated wear increment 315-1, for the total wear of the vacuum pumps 10, 111. After being pre-added to the variable 325, it can be added to the variable 325 for the total wear of the vacuum pump 10,111.

After a waiting period at 390, steps 340 to 380 are repeated, first determining at 340 whether another new attempt to stabilize rotor 12, 149 should be made. When method steps 340 to 380 are executed anew, additionally it is checked whether the trouble event detected in 310 is still present. When this is not the case, the probability of successful stabilization of rotor 12, 149 is greatly increased. Therefore, in this case, at 350 it is determined that stabilization of the rotor 12, 149 should be performed. However, if rotor 12, 149 fails to stabilize again, which is determined at 370, steps 390, 340, 350, 370 can be repeated iteratively, whereupon the waiting time at 390 is Each failed attempt to stabilize 12,149 is lengthened.

Additionally, the wear record for the safety bearings 215 in the memory 320, ie the variable 325 for the total wear of the vacuum pumps 10, 111, indicates the operating set point for the turbomolecular pump, as suggested by the arrow 395. It is possible to influence the set 330 . For example, during a trouble event, the prioritization between operating states to be achieved for the vacuum pump 10,111 can be changed based on the value of the variable 325 for total wear of the vacuum pump 10,111. In this case, the set 330 of operating settings for the vacuum pump 10, 111, in addition to the operating conditions themselves to be achieved, 340 and 340 and It also includes values for prioritization between these operating states available at 350 .

The recording of wear for safety bearing 215 is detailed below based on numerical examples of variable 325 for wear increment 315-1 and total wear. The numbers are typical for vacuum pumps 10, 111 which are turbomolecular pumps. However, the values may vary depending on the type of vacuum pump and may take values other than those stated.

As previously mentioned, variables 325 for wear increment 315 - 1 and total safety bearing 215 wear are each related to a percentage of the total useful life of safety bearing 215 . The wear record is such that a variable 325 for the total wear of the safety bearing 215 is first initialized to zero, followed by a wear increment 315- It is done so that it is incremented by one. An error notification is output when the variable 325 for total safety bearing 215 wear reaches a value of 100%. A value of 100% for total wear therefore corresponds to the expected service life of the safety bearing 215 .

When the variable 325 for the total wear of the safety bearings 215 reaches this 100% value, e.g. In order to record the wear of the bearing 215 as completely as possible, it continues to be increased by the wear increment 315-1 until the vacuum pump 10, 111 is stopped. Thereby, the variable 325 may assume a value greater than 100%, eg 130%, when the vacuum pump 10, 111 is stopped.

And vice versa, it is possible to initialize the variable 325 for the total wear of the safety bearing 215 with a value of 100%. In this case, variable 325 is decremented by wear increment 315-1 for each trouble event. An error notification is output when variable 325 reaches a value of 0% in this "negative counting method" of wear increments. For a complete wear record, variable 325 may take a negative value, eg -30%, until vacuum pump 10, 111 shuts down, corresponding to the previous example.

As seen in FIG. 8, different process or method steps 310, 360, 390 result in different wear increments 315-1, 315-2, 315-3. For example, in step 360, the operating speed of the vacuum pump 10, 111, i.e., the complete stop operation from the reachable end speed of the vacuum pump 10, 111 to the stop state, while maintaining the vacuum, increases the wear by 41%. yields quantity 315-2. This wear increment 315-2 is simply composed of two components. The first component results from the initial acceleration of the free-running portion of the safety bearing 215 and is 1% in this example, while the second component is the actual acceleration of the rotor 12, 149 in safety bearing operation up to standstill. It arises from the stopping motion and is 40% in this example. However, when the time of the stop motion of the rotor 12, 149 can be halved, for example by venting the vacuum installation in which the vacuum pump 10, 111 is present or by dynamic braking of the vacuum pump 10, 111, to a first approximation wear The increment 315 is also halved to a value of approximately 20%. In this case, the full stopping motion of the rotor results in a wear increment 315-2 of 21% when the two components are summed.

The trouble event that results in safe bearing operation at step 310 (see FIG. 8) can be short term or persistent. If the trouble event disappears after a short period of time, a full kill-stop operation of rotor 12, 149 will not be performed. This is because an immediately following attempt to re-stabilize the active magnetic bearings and rotor 12, 149 may be immediately successful. In such cases of very short safety bearing operation with restabilization, the wear increment 315-3 typically consists of three components. The first component again results from the initial acceleration of the safety bearing 215 and is 1%, while the second component results from the actual process of restabilization and is about 1.5% wear increment 315 -3. The third component relates to the free stopping motion of the safety bearing 215 until it stops, with a value resulting in a wear increment 315-3 of about 0.5%. Therefore, infrequently occurring short-term troubles involving short-term safety bearing operation of a few seconds duration generally account for 3% of resulting in a wear increase of 315-3.

If this initial attempt to re-stabilize the rotor 12, 149 is unsuccessful, e.g., based on continuing trouble, further or other forms of wear increment 315- 3 is produced. When an unsuccessful re-stabilization attempt is followed by a full stop motion of the rotor 12, 149, this full stop motion will have a wear increment 315-2, depending on the duration until the rotor stops, as previously described. yields values of 20% to 40% for On the other hand, however, the value for the stopping movement of the safety bearing 215 after the end of restabilization does not occur, since this stopping movement does not take place. In summary, therefore, during longer lasting troubles, an unsuccessful restabilization attempt is followed by venting the vacuum pump 10, 111 from operating speed to shutdown. The wear increment 315-2 for longer lasting troubles where full stop motion is performed has the following components: i) 1% based on the acceleration of the safety bearing 215; 5% and iii) 20% based on a quick full shutdown operation with venting of the vacuum pumps 10,111. Therefore, in total, the wear increment 315-2 is 22.5% in this example.

Moreover, instead of a complete stop operation with venting of the vacuum pumps 10, 111, after a predetermined period of time or when the vacuum pumps 10, 111 fall below a predetermined rotation speed during the gradual stop operation, restabilization Another trial of conversion may be performed. The predetermined period is, for example, 2 minutes, 1 minute or 0.5 minutes from the start of the safety bearing operation, while the predetermined speed is, for example, half the operating speed. A new attempt to re-stabilize the rotor 12, 149 may be successful. This is because the trouble is tapering off in the meantime or the rotor 12, 149 can be better restabilized based on the lower gyroscopic forces when the low rpm is maintained. Regardless of the success of the new restabilization, the new stabilization is accompanied by another value of wear increment 315-2 or 315-3, for example 0.9%. If both restabilization attempts failed, the trouble detected at 310 (see FIG. 8) would result in an overall increase in wear of 23.4% instead of 22.5%, which is equivalent to a single re-stabilization attempt. A previous example with a stabilization trial followed by a complete shut down operation of the vacuum pumps 10, 111 was identified. In contrast, a successful second re-stabilization attempt does not produce a value for partial stop operation from half operating speed of the rotor 12, 149 to stop, which is a wear increment of about 6%. leading to a reduction of 315-3. However, a value is added for the free stopping motion of the safety bearing 215, which is approximately 0.2% based on the already reduced speed of the rotor 12,149. If the first restabilization attempt fails after the trouble and the second restabilization attempt succeeds, the resulting wear increment 315-3 totals about 17.6%.

The values of the wear increments 315-1, 315-2, 315-3 are based on the operating parameters of the vacuum pumps 10, 111, for example, the current rotation speeds of the rotors 12, 149 of the vacuum pumps 10, 111 and the vacuum pumps 10, 111 and the condition of the safety bearing 215. As noted above, at the operating speed of the vacuum pumps 10, 111, the value of the restabilization trial for the wear increment 315-3 is about 1.5%, while at half the operating speed, the corresponding The value is only about 0.9%. The value of the initial acceleration when entering safety bearing operation is approximately 1.0% at the operating speed of the vacuum pumps 10, 111 and 0.4% at half operating speed. For the free stop action of the safety bearing 215, the values are approximately 0.5% at the operating speed of the vacuum pumps 10, 111 and 0.2% at half operating speed.

In addition, the type of trouble event detected in method step 310 of FIG. is allowed. Thus, the type of trouble event affects the values for the wear increments 315-1, 315-2 that occur during initial acceleration of the safety bearing and the probability of a successful restabilization. Initial safety bearing contact tends to progress slowly when the motion regime is slowly increasing or at least continuously steady and possibly sustained. This gives the safety bearing 215 more time to complete the initial acceleration when the bearing load is lower. On the other hand, when the motion regime is chaotic and impulsive, with high gradients and possibly sign changes, the reaction of active magnetic bearings is also complex, corresponding to a chaotic overview. . In this case, initial safety bearing contact tends to occur randomly during strong impacts, correspondingly leading to quick safety bearing contact with high load capacity. This causes increased wear increments 315-1, 315-2, 315-3 compared to troubles followed by slow rotor 12, 149 and stator non-chaotic mutually approaching motion regimes. .

Approximately, the wear increments 315-1, 315-2, 315-3 are assumed to depend primarily on the rotational energy of the rotors 12, 149 and secondarily on their rotational speed. In particular, the values for the wear increments 315-1, 315-2, 315-3 can be determined by various processes depending on the respective number of revolutions of the rotor 12, 149 and/or directly at that time. It can be specified depending on the respective rotational energy present or the loss of rotational energy that occurs over a given period of time due to safety bearing operation. The amount of energy extracted from or supplied to the rotor 12, 149 in ways other than through safe bearing operation may be considered. Such an amount of energy is, for example, the drive energy to the drive of the rotor 12, 149 and/or the braking energy from the drive of the rotor 12, 149, or the respectively existing known vacuum pressure and/or flowing gas. is a hypothetical calculated value based on the rotor 12, 149 gas friction that occurs.

The values for the wear increments 315-1, 315-2, 315-3 caused by the initial acceleration of the safety bearings at the onset of trouble with safety bearing operation are the number of revolutions and/or revolutions of the rotor 12, 149 as parameters. It can be inferred as a rare event with energy. In the other processes mentioned above that occur after the onset of trouble and continue for some period of time, this period, the rotor rpm at the beginning and end of the period, and possibly the course of the rotor rpm over the period, are the wear increments. It is a calculation factor of values for 315-1, 315-2, 315-3. For example, the known period of free motion stoppage of the safety bearing 215 after the end of the trouble is used to estimate the respective remaining relative number of rotations or number of rotations of the safety bearing 215 . Adapted reduced wear increment 315- by taking into account the required acceleration and thus the speed difference between the safety bearing and the mating side when multiple troubles with safety bearing operation occur in quick succession. 1, 315-2, 315-3 can be identified. Values for wear increments 315-1, 315-2, 315-3 caused by processes having sufficiently long durations of minutes rather than seconds are obtained using the rotational speed and/or rotational energy of rotors 12, 149 as parameters. and then there is a time- and/or speed-dependent calculation formula for the wear increments 315-1, 315-2, 315-3, in which the respective process It is integrated over a period and/or speed range.

The processes responsible for the wear increments 315-1, 315-2, 315-3, in various ways, are the rotational speed and/or rotational energy of the rotor 12, 149 and safety bearing 215 components and/or the currently generated depending on the bearing load applied. The process can be performed, for example, on the starting and ending speeds, or on the course of the speed of each component, and the bearing loads acting during it and/or the rotational energy present, as well as the values of these parameters during the respective process. Depends on the sequential course.

The respectively present bearing load, in a simplified manner, likewise depends primarily on the rotational energy and thus secondarily on the rotational speed. Depending on the configuration and/or installation orientation, there may typically be different bearing load or partial bearing load relationships between different bearing locations. For example, the cantilever bearing of the rotor 12, 149, which has a center of gravity outside of all bearing locations in all installation orientations of the vacuum pump 10, 111, among other things, allows the axis of rotation of the rotor 12, 149 to be largely in space. , at least two mutually spaced bearing locations in the direction of the axis of rotation of the rotor 12, 149, acting in opposite directions. bearing forces can be generated.

Knowing the geometrical parameters of the rotor 12, 149 and stator of the vacuum pump 10, 111, such as the distance from the bearing location, the center of gravity, the mass moment of inertia and the natural frequencies and/or bending critical modes, the It is possible to identify the relationship between the wear increments 315-1, 315-2, 315-3. Furthermore, knowing the orientation of the vacuum pumps 10, 111 in space, ie the direction of gravity acting on the components of the vacuum pumps 10, 111, the wear increments 315-1, 315-2, 315-3 can be calculated. can be adapted accordingly. This is because, for example, in a particular orientation there may be a higher or lower individual bearing point load relative to the standard orientation.

When the wear of the safety bearing 215 is expected to vary significantly at each different bearing location, the safety bearing wear can alternatively be calculated for each individual bearing location rather than using a single variable 325 for total wear. , is determined and recorded for each bearing location direction of action, and even for each bearing location partial segment. For example, when the axis of rotation is arranged horizontally in space during safety bearing operation, the fixed bearing points can be subjected to high radial loads and the wear associated therewith, whereas axial loads and the associated wear is minimal. This is because the rotor weight does not create an axial load bearing for this spatial orientation of the vacuum pumps 10,111.

By means of active position detection of all axes of the active magnetic bearing (see FIGS. 6 and 7), a one It is further possible to identify one or more initial contact points. Depending on the sequence, different wear increments can be identified and recorded for each bearing location. The locally limited wear increment of the bearing ring running surface is spatially resolved for the first contact position, which always remains the same on the circumference of the fixed side of the safety bearing 215, and thus for the first direction of action of full load capacity. can be stored as

Such storage of the wear increment 315 and the resulting total wear for each safety bearing 215, associated with the bearing location and/or bearing axis, can be communicated directly to the user or can be communicated directly to the user, or by calculation based on a formula, to the total wear value. Alternatively, it may be recalculated into multiple partial wear values. For example, considering pure maximum or minimum values, only the maximum or minimum of all wear values per safe axis, i.e. the worst or best of all partial values, can be defined and communicated as total wear. . Additionally, the total wear can be calculated and communicated in a more balanced manner by weighting the various partial values.

An error message and/or a safe shutdown of the vacuum pump when threshold values for wear are exceeded are correspondingly based not only on the height of the total wear, but also on the individual partial values or one of the partial values. or solely on the basis of the individual partial values or one of the partial values. The internal storage of the various part values generally allows a service technician, upon inspection of the vacuum pump 10, 111 at a later point in time, to select only those elements which have actually worn and/or which have been subjected to the greatest amount of wear. Allows replacement, adjacent or normal range-exposed components to be more closely controlled, thereby optimizing the quality and efficiency of inspection or maintenance.

When the supply voltage of the vacuum pumps 10, 111 is lost, the aforementioned emergency supply can ensure continued operation of the active magnetic bearings, at least for a limited period of time. Loss of supply voltage possibly disturbs or prevents storage of each wear increment 315-1, 315-2, 315-3 in memory 320. FIG. However, the aforementioned loss of supply voltage can be recognized in time, illustratively by observing the onset of supply voltage drop prior to an intermediate storage, e.g. a capacitor, secured against backflow of energy by a diode. . When activation of the emergency supply is possible, e.g. by means of a power supply, activation can take place immediately after the loss of supply voltage. In this case, no safety bearing action occurs.

During emergency supply, or already at the onset of loss of supply voltage, the remaining number of revolutions of the rotor 12, 149 or other operating parameters, such as the remaining charge of the emergency battery, may be It is no longer sufficient to maintain the supply and active magnetic pivoting. To eliminate such a situation, at any point during the loss of operation, the partial switch-off of the electrical load not required for the active magnetic bearing, such as the remaining revolutions or the current generation feedback voltage, etc. It can be done depending on the parameters. Electrical loads considered for partial switching off are, for example, interface modules or accessory components. The order, and thus the importance, of the individual elements can be determined a priori or dynamically based on operating parameters. For example, an interface module can be switched off later when it has an active data connection.

Any possibility of delaying the failure of the active magnetic bearing is exploited, before the loss of emergency supply, the orderly switch-off of the active magnetic bearing, e.g. , 149 and/or final storage of wear increments 315-1, 315-2, 315-3. In this case, for the rest of the stopping motion of the rotor 12, 149, the dynamically adapted wear increment based on preset or known operating parameters is stored even before the actual end of the stopping motion. Or at least stored in a non-volatile buffer memory so that final storage can be done later on reuse or restoration of the supply voltage.

The control of the vacuum pump 10, 111 or of the active magnetic bearing also determines whether a previous switch-off of the active magnetic bearing with the rotor 12, 149 at rest has taken place each time the supply voltage is restored. I can check. To that end, a data identifier may be provided in a non-volatile memory in which during normal operation of the active magnetic bearing assembly when the rotor 12, 149 is in stationary operation, a first A value of 1 is assigned. The data identifier is reset to a second value each time the rotor begins to rotate. When the data identifier does not have its original value upon restoration of the supply voltage, it is probable that the last shutdown did not occur in normal operation.

When the operating parameters of the vacuum pumps 10, 111 are continuously or at least regularly stored in a non-volatile manner at specific time intervals, after a loss of the supply voltage, the wear increments 315-1, 315-2, 315-3 can be calculated and added in memory 320 to the variable 325 for total wear. However, this process places high demands on the memory 320, which must store data non-volatile on the one hand and always or at least very frequently on the other hand. Therefore, the expected service life of the memory 320 is sufficient so that it does not limit the overall service life of the vacuum pump 10, 111 more severely than safety bearing wear or deterioration of other components of the vacuum pump 10, 111. must be long.

When performing method 300, for each of the aforementioned processes involved in safety bearing wear, each individual partial wear increment may be stored in memory 320 as directly as possible. Thus, at any point in time, the current state of total safety bearing wear is stored and can be communicated. This means that when a complete loss of supply voltage occurs in addition to the actual safety bearing operation, for example, the user may undesirably troubleshoot by emergency shutdown of the installation and then possibly the full operation of the rotor 12,149. It is also advantageous when there is not enough time left or not enough energy left to store the current wear increment.

The iterative execution of method steps 340, 350, 370 and 390 of FIG. 8 will now be detailed on the basis of an example. Repeated execution of these method steps corresponds to repeated execution of restabilization attempts, during which the waiting time occurring at step 390 increases with each iteration.

The controller of the vacuum pump 10, 111 additionally has two counters that are used in controlling the repeated execution of restabilization attempts. A first counter determines the waiting time 390 between two restabilization attempts, while a second counter counts the number of restabilization attempts after detection of a trouble event (step 310 in FIG. 8). Get the numbers that reflect. During normal operation of the vacuum pumps 10, 111, ie unless a trouble event occurs, the first and second counters are initially initialized to zero.

A first pump-specific value is assigned to the first counter. At the start of each restabilization attempt, the first pump-specific value is multiplied by the current value of the second counter and assigned to the first counter. A second counter reflects the number of restabilization attempts, thereby progressively increasing the period or delay between restabilization attempts, as will be discussed in more detail below.

The first pump eigenvalue is, for example, in the range of 10 to 99, and is 10 in this numerical example. Thus, in this example, the waiting time between restabilization attempts is progressively increased by a multiple of 10 after the second restabilization attempt.

After incrementing, the first counter is decremented by 1 every second, and in principle a restabilization attempt is made only when the first counter is equal to zero. The first counter thereby controls the delay or waiting time 390 between restabilization attempts.

As soon as a trouble event is detected at 310 (see FIG. 8), the controller attempts to perform a restabilization attempt after each short period of time, eg, every second. However, since each restabilization attempt is performed only when the first counter is equal to zero, each restabilization attempt can be delayed by the first counter.

The second counter is initialized at 0 and is assigned the product of the first pump-specific value and the value of the second counter, so that the first counter Still equal to 0 after a stabilization attempt. Therefore, a second restabilization attempt can be made immediately after the first restabilization attempt.

Following this, the second counter is incremented by a second pump-specific value, which for example ranges from 1 to 9, and is 1 in this numerical example. Thus, in this example, the second counter counts restabilization attempts after a trouble event and is therefore equal to 1 after the first restabilization attempt.

If the first re-stabilization attempt is successful, the vacuum pump 10, 111 goes into normal operation, with the first counter and the second counter being set to zero again. However, if the first restabilization attempt fails, a second restabilization attempt is made after one second. This is because the first counter is still equal to zero. At the start of the second restabilization attempt, in the present example, the first counter is first assigned the value 10, ie the current value 1 of the second counter is multiplied by the first pump-specific value 10, followed by A second counter is incremented to two.

If the second re-stabilization attempt is successful, the vacuum pump resumes normal operation while the first and second counters are set to zero again. However, if the second restabilization attempt fails, the waiting time before the third stabilization attempt is 10 seconds. This is because the value 10 of the first counter is decremented by 1 every second and only when the first counter is equal to 0 again does the next restabilization attempt take place.

When the trouble event still continues after 10 seconds, a third restabilization attempt is made, with the first counter being assigned a value of 20 and the second counter increasing to the third restabilization attempt. fails, you get the value 3. Otherwise, both counters are equal to 0 again.

After the third unsuccessful restabilization attempt, the first counter equals 0 and it takes 20 seconds before a further restabilization attempt can be made. Thus, the waiting time 390 between two further restabilization attempts is extended by a number of seconds corresponding to the first pump eigenvalue for each unsuccessful restabilization attempt. In other words, new restabilization attempts become “unattractive” with each failed restabilization attempt.

A particular set of operating settings 330 (see FIG. 8) for the vacuum pump 10, 111 is used when repeatedly performing the plurality of restabilization trials described above. Set 330 includes, for example, the operating settings "keep vacuum pump running" and "progressively delay re-stabilization attempts". Correspondingly, re-stabilization attempts are performed repeatedly to first prevent full stop motion of the rotor 12, 149, and the waiting time between re-stabilization attempts is Longer with each failed attempt.

A set of operating setpoints, alternatively or additionally to one or more static operating setpoints, e.g. "avoid safety bearing operation as long as possible, keep period of safety bearing operation as short as possible" 330 may include a plurality of sets of operational settings or rules that are dynamically adaptable and responsive to operating conditions. These operating set values may be fixed in advance, or may be changed according to the operating state of the vacuum pumps 10, 111 or the priority set by the user. Additionally, operating settings can be implemented and adapted by adaptive or self-learning algorithms.

At the start of safety bearing operation, the hold and progress of trouble events are unknown for the controls of the vacuum pumps 10, 111 or the controls of the active magnetic bearings. However, it is known what wear increment 315-2 would occur in the worst case of a complete stop motion of rotors 12,149. Additionally, as previously described, the additional wear increment 315-3 caused by each restabilization attempt can be estimated. The type and severity of trouble that caused safe bearing operation can also be known based on sensor data.

The set of operating settings 330, for example user settings, also include the possibility of venting the vacuum pumps 10, 111 and thus rapid external braking or energy feedback to the installation voltage supply. or even dynamic braking of the rotor 12, 149 without or via a built-in load resistor. Some of the set of operating settings 330 may also be set by the user directly or by the nature of the vacuum equipment in which the vacuum pump 10, 111 is located. For example, conflicting setpoints "keep vacuum pump running" or "minimize safety bearing wear" may be included, and these setpoints may be set by the user and/or the vacuum equipment or vacuum pump 10, 111 are prioritized according to their current operating conditions.

For the operating setpoint "always keep the vacuum pump running", rather than typically stopping the drive of the rotor 12, 149 in safety bearing operation as is normal, for example, interrupting a process batch and resulting To avoid subsequent costs, it may be reasonable to keep the rotor at operating speed as long as necessary. In addition, the facility controller optionally sets the time for bringing the pre-vacuum pump to operating speed and/or opening the valve slider of the pre-vacuum pump toward the vacuum facility and at the same time shutting off the corresponding vacuum pump. This ensures a stable and maintained vacuum pressure within the vacuum system. When a trouble event persists, the operational setpoint "Always keep the vacuum pump running" becomes less important after a certain period of time and other operational setpoints, such as "Stop equipment and vacuum pumps as quickly as possible", become less important. have a higher priority.

The operating setpoint "stop the vacuum pump as quickly as possible" assumes that no restabilization takes place. Instead, the safety bearing action, and thus the rotational energy that can be extracted from the rotor 12, 149, maximizes the braking effect on the rotor 12, 149, allowing the vacuum pump 10, 111 to stop, at the expense of safety bearing wear. possible in the shortest possible time.

In addition to the above operating setpoints, which constitute extreme examples, there are several other operating setpoints, such as "re-stabilize as quickly as possible" or "rotor speed while minimizing safety bearing wear." is possible to maintain at least half of However, in the absence of special peripheral conditions, an "optimized standard condition" is typically set for the set of operating settings 330, the primary goal of which is low safety bearing wear. The details of such a set of operational settings 330 are described below.

When a trouble event occurs, it is first checked whether the trouble event continues or has been resolved. A restabilization attempt is made when the trouble event can no longer be recognized. The rule then applies that the wear increment of a restabilization attempt 315-3 must be less than the wear increment of a potential full stop motion 315-2. When the rotation speed of the rotor 12, 149 is already very low, for example while the vacuum system is switched off and accidentally the vacuum pump 10, 111 is already moved before it stops, the full stop operation of the rotor 12, 149 is safe. More favorable with respect to bearing wear. In contrast, a restabilization attempt, at very low speeds, can again lead to further trouble events with safe bearing operation, which can lead to further wear increments 315-1, 315-2, 315 -3 is generated.

When restabilization is not successful, the less time that has passed since the previous attempt, the higher the probability that the next attempt will also fail. This is because, for example, the trouble event has not yet subsided, or the rotor 12, 149 has too much rotational energy in an unfavorable installation position of the vacuum pump 10, 111, and therefore the active magnetic bearing This is because stabilization by existing means cannot be carried out. In both cases, it is preferable to wait for the end of the trouble event or to wait for a decrease in rotational speed or rotational energy.

Trouble termination is actively detected using, for example, the sensors described above. Furthermore, it is possible to wait for the rotational speed and thus the rotational energy to decrease, for example by a predetermined value or a value specified as part of the operating rotational speed. Additionally, a wait time 390 during a restabilization attempt can be set or specified depending on the operating speed. One or a combination of the foregoing events triggers a new restabilization attempt which, in turn, indicates that the expected wear increment 315-3 at this point is 0 for the rest of the stopping motion of the rotor 12,149. can be performed only when the wear increase amount 315-2 is smaller than . Alternatively, a restabilization attempt is triggered immediately by the operating conditions of the vacuum installation or upon a corresponding request by the user.

10 Vacuum Pump 12 Rotor 14 Turbo Rotor Disk 16 Motor 18 Rotor Axis 20 First Radial Bearing 22 Thrust Bearing 24 Second Radial Bearing 26 First Radial Sensor Assembly 28 Second Radial Sensor Assembly 30 Components 32 Motor Chamber 34 Radial sensor assembly 36 board 38 coil 111 turbomolecular pump 113 inlet flange 115 pump inlet 117 pump outlet 119 housing 121 lower part 123 electronics housing 125 electric motor 127 accessory connection 129 data interface 131 current supply connection 133 vent intake Mouth 135 Seal gas connection 137 Motor chamber 139 Coolant connection 141 Lower surface 143 Screw 145 Bearing cover 147 Fixing hole 148 Coolant line 149 Rotor 151 Rotation axis 153 Rotor shaft 155 Rotor disk 157 Stator disk 159 Spacer ring 161 Rotor hub 163 Holder Beck rotor sleeve 165 Holweck rotor sleeve 167 Holweck stator sleeve 169 Holweck stator sleeve 171 Holweck gap 173 Holweck gap 175 Holweck gap 179 Connection channel 181 Rolling bearing 183 Permanent magnet 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 gap 201 support part 203 support part 205 radial strut 207 cover element 209 support ring 211 fixing ring 213 disc spring 215 emergency or safety bearing 217 Motor Stator 219 Intermediate Chamber 221 Wall 223 Labyrinth Seal 300 Method of Operating Vacuum Pump 310 Trouble Events Detected 315-1 Estimated Wear Growth 315-2 Initialized Wear Growth 315-3 Initialized Wear Growth 320 memory 325 variable for total safety bearing wear 330 set operating setpoints for vacuum pump 340 mediation between variable for total wear and set of operating setpoints 350 rotor stabilization?
360 Vacuum pump shutdown 370 Stabilization successful?
380 Normal operation of vacuum pump 390 Standby time 395 Arrow

Claims (15)

It has a rotor (12, 149), a stator, actively controlled magnetic bearings (20, 22) for journaling the rotor (12, 149), and a safety bearing (215) for the rotor (12, 149). In a method of operating a vacuum pump (10, 111), comprising:
The method is
A set (330) of operating settings for the vacuum pump (10, 111) is provided, the set (330) of operating settings for the vacuum pump (10, 111) to be achieved in the event of at least having one operating state,
A trouble event is detected, and when the trouble event occurs, the rotor (12, 149) moves away from the spatial area set for the rotor (12, 149) with respect to the stator, and wear occurs in the safety bearing (215). occur,
estimating a wear increase amount (315-1) for the safety bearing (215) based on the detected trouble event;
Adding the wear increment (315-1) to the variable (325) for the total wear of the safety bearing (215),
Stabilize the rotor (12, 149) based on a set (330) of operating settings for the vacuum pump (10, 111) and based on a variable (325) for the total wear of the safety bearings (215) determine whether to carry out the means,
Having a method. 2. A method according to claim 1, wherein the vacuum pump (10, 111) is shut down when it is determined not to carry out the means for stabilizing the rotor (12, 149). checking if the means for stabilizing the rotor (12, 149) were successful; then, if the means failed, after a predetermined waiting time (390), the means for stabilizing the rotor (12, 149). At that time, another wear increase amount (315-2, 315-3) is specified, and another wear increase amount (315-2, 315-3) is set to the safety bearing (215) 3. The method of claim 1 or 2, adding to the variable (325) for the total wear of the . 4. Any of claims 1 to 3, wherein the variable (325) for the total wear of the safety bearings (215) exceeds a certain threshold, shutting down the vacuum pump (10, 111) and/or outputting an error notification. or the method described in paragraph 1. Method according to any one of claims 1 to 4, wherein the values of the wear increments (315-1, 315-2, 315-3) are estimated on the basis of experimental data and/or on the basis of empirical values. . Claim 5, wherein the value of the wear increment (315-1, 315-2, 315-3) is estimated based on measurements of at least one sensor (26, 28) identified during the trouble event. The method described in . The value of the wear increment (315-1, 315-2, 315-3) depends on the rotation speed of the rotor (12, 149) when the trouble event begins and/or the vacuum pump (10, 111) 7. The method according to any one of claims 1 to 6, estimating depending on the installation attitude of the . The wear increment (315-1, 315-2, 315-3) includes at least two parts, the first of which is based on the initial acceleration of the safety bearing (215) when the trouble event begins. , the second part is the expected safety bearing (215 ), the method according to any one of claims 1 to 7. The set (330) of operating settings for the vacuum pump (10, 111) has at least two operating states of the vacuum pump (10, 111) to be achieved in the event of a trouble, the operating states being the vacuum 9. A method according to any one of the preceding claims, comprising maintaining a vacuum in the pump (10, 111) and shutting down the vacuum pump (10, 111). 10. Method according to claim 9, wherein the operating conditions to be achieved in the event of a trouble are prioritized by the user of the vacuum pump (10, 111) and/or by a learning algorithm. The amount of wear increase (315-1) for the safety bearing (215), estimated based on the detected trouble event, during the means for stabilizing the rotor (12, 149) or the vacuum pump (10, 111 ) and replaces the previously estimated wear increment (315-1) with the updated wear increment (315-2, 315-3), which is the total of the safety bearing (325). 11. The method of any one of claims 1 to 10, adding to a variable (325) for wear. The safety bearing (215) has a plurality of bearing points, and the method identifies respective wear increments (315-1, 315-2, 315-3) for each bearing point and 12. A method according to any preceding claim, further comprising adding to each variable (325) for total wear. In the vacuum pump (10, 111),
a rotor (12, 149);
a stator;
actively controlled magnetic bearings (20, 22) for supporting the rotor (12, 149);
a safety bearing (215) for the rotor (12, 149);
at least one means for detecting a trouble event, wherein when the trouble event the rotor (12, 149) moves away from the spatial region set for the rotor (12, 149) with respect to the stator, a safe at least one means for detecting a trouble event in which wear occurs in the bearing (215);
a controller;
a memory (320) containing a variable (325) for the total wear of the safety bearing (215);
with
A vacuum pump (10, 111), the controller being configured to perform the method according to any one of claims 1 to 12. The memory (320) can only add the wear increment for the safety bearing (215) to the variable (325) for the total wear of the safety bearing (215); 14. The vacuum pump (10, 111) of claim 13, configured to keep the variable (325) for total wear of the safety bearing (215) unchanged during the total service life of the safety bearing (215). At least one means for detecting a trouble event comprises sensors (26, 28) configured to detect the spatial position of the rotor (12, 149) and/or vibration and/or acceleration sensors mounted on the stator. 15. A vacuum pump (10, 111) according to claim 13 or 14, comprising.

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