JP2021038744A - Vacuum pump - Google Patents

Abstract

To improve the controllability of displacement of a rotor, particularly enable further improved countering the vibration of the rotor, and/or improve the stability of control of a magnet bearing.SOLUTION: There is provided a second radial sensor assembly which identifies a displacement in a radial direction in a second axial region different from a first axial region.SELECTED DRAWING: Figure 8

Description

The present invention is a rotor that can be rotationally driven to exert a pumping action and first and second radial bearings for the rotor, preferably the first radial bearing is an active control type magnetic bearing. The second radial bearing is a vacuum pump, particularly a vacuum pump, comprising first and second radial bearings configured as passive magnetic bearings and a radial sensor assembly that identifies the radial displacement of the rotor. Regarding turbo molecular pumps.

Vacuum pumps in which the pump rotor is magnetically supported, especially turbo molecular pumps, are known. Magnetic bearings have many advantages, in particular magnetic bearings allow the pump to operate without friction and lubricants. In this case, on the inlet side, usually passive magnetic bearings, especially permanent magnet magnetic bearings, are used to fix the position of the rotor in the radial direction. At the rotor end on the opposite side, active-controlled magnetic bearings are often used to secure both the radial and axial positions of the rotor. Therefore, an oilless pump can be realized by a simple and low-cost means. Active control of magnetic bearings includes radial sensors that are placed, especially in the case of magnetic bearings. Depending on the displacement of the rotor as measured by the radial sensor, the electromagnets of the active magnetic bearings are driven and controlled to exert a force on the rotor in the opposite direction of the displacement.

An object of the present invention is to improve the control of the displacement of the rotor, in particular to better counter the vibration of the rotor, and / or the stability of the control of the magnetic bearing in the vacuum pump of the form described at the beginning. To improve.

The challenge is to use a vacuum pump with the characteristics of claim 1 to provide a second radial sensor assembly that identifies radial displacement, especially in a second axial region that is different from the first axial region. It is solved by being provided. This problem is also solved by the vacuum pump according to claim 2. In this vacuum pump, in particular, a first radial sensor assembly is axially associated with the first radial bearing and / or placed beside the first radial bearing. Preferably, and in principle irrespective of this, the second radial sensor assembly may not be axially associated with, for example, either the first radial bearing or the second radial bearing, and / Or it can be separated from both radial bearings.

The second radial sensor assembly in the second axial region, in combination with the first radial sensor assembly in the first axial region, allows the tilt of the rotor to be determined. Such tilt is represented by the first and second radial sensor assemblies determining different displacements of the rotor. The known tilt allows for better control of rotor displacement and better prevention of vibration.

The displacement is generally relative to the zero axis, which is the ideal rotation axis of the rotor. When there is a displacement, the rotor axis deviates from the zero axis.

For example, the second radial bearing can be configured as a magnetic bearing. According to one embodiment, the second radial bearing is configured as a passive magnetic bearing. For example, the second radial bearing can be configured as a permanent magnet bearing.

The first radial sensor assembly and / or the first axial region may be located, for example, beside the first radial bearing and / or adjacent to the first radial bearing. Therefore, for example, the displacement of the rotor in the first radial bearing can be measured with high accuracy.

According to one improved form, the axial distance a is defined by the axial distance between the axial center of the first radial sensor assembly and the axial center of the first radial bearing, and the second. The axial distance b is defined by the axial distance between the axial center of the radial sensor assembly and the axial center of the second radial bearing, and the ratio b / a is preferably at least 2. Is assumed to be at least 3.5, preferably at least 5, and even more preferably at least 7.

In general, the first axial region may correspond to the axial center of the first radial sensor assembly and / or the second axial region corresponds to the axial center of the second radial sensor assembly. Can be done.

According to another embodiment, a second axial region or a second radial sensor assembly is disposed between the first radial bearing and the second radial bearing. This allows a relatively large distance in the axial region of these radial sensor assemblies to be achieved while maintaining the compact configuration of the pump, which improves measurement accuracy.

Preferably, the distance c is defined by the axial distance between the axial center of the first radial bearing and the axial center of the second radial bearing, and the partial region of the axial center of the distance c. Has an axial length d, the second radial sensor assembly is located in a partial region with its axial center, and the ratio d / c is preferably 0.7, preferably 0.7. Is 0.5, preferably 0.4.

According to some embodiments, it can be assumed, for example, that a second axial region is located between the motor for the rotor and the second radial bearing. This also makes it possible to achieve high measurement accuracy with a compact configuration. For example, motors can be placed between radial sensor assemblies. According to some embodiments, a second radial sensor assembly may be placed on a component that defines the motor chamber and / or forms the motor housing. In general, for example, the second radial sensor assembly can be separated from the second radial bearing.

Alternatively or additionally, for example, at least one rotor element, preferably a plurality of rotor elements, may be provided between the second axial region in the axial direction and the second radial bearing. It can be assumed. The one or more rotor elements may preferably be the turbo rotor elements of a turbo molecular pump. In particular, the axial direction of the rotor element in which the second radial sensor assembly is located closest to and / or farthest from the second radial bearing on the outlet side with respect to the second radial bearing. It can be assumed that it is located behind. In general, preferably, the second radial sensor assembly can be located on the outlet side, eg, axially, with respect to one or more pump stages, especially the turbo stage.

In general, the vacuum pump can preferably be a turbo molecular pump, particularly a turbo molecular pump having a three-axis active magnetic shaft branch and a passive magnetic shaft branch.

For example, it can be assumed that a tilt control device is provided for the rotor. Therefore, the rotor can be controlled better, and various displacements along the rotor axis can be accurately minimized. A second radial sensor assembly and / or tilt controller allows the rotor to be dynamically controlled, as opposed to exclusively static control with only one radial sensor assembly.

According to one embodiment, the actuator system of the tilt control device is formed by a first radial bearing. That is, the force against the displacement is transmitted from the first radial bearing to the rotor shaft. To that end, the first radial bearing has, for example, an electromagnet. According to another embodiment, the actuator system of the tilt control device is formed exclusively by the first radial bearing. Therefore, the first radial bearing alone provides compensation for rotor tilt. This makes control more complex and eliminates the need for additional actuator systems that would require additional components. However, in principle, alternative or additionally, the actuator system of the tilt controller can also be formed, for example, by active thrust bearings. For example, the second radial bearing is passively configured and does not actively participate in tilt control.

The tilt control device may be configured to compensate, for example, by compensating for the tilt of the rotor by exerting impact and / or impact on the rotor. This provides an easily viable means of reducing the tilt of the rotor. Impact and / or impact effects can be provided, for example, exclusively in a single axial region and / or exclusively by the first radial bearing.

In some embodiments, a second radial bearing is located on the inlet side and / or a first radial bearing is located at the end of the rotor opposite the pump inlet and / or outlet. It is located on the side. In general, the second radial bearing may be located on the upper side and / or the first radial bearing may be located on the lower side, for example in a suitable operating position of the pump. However, especially in the context of split flow pumps, these radial bearings may be arranged, for example, in a horizontal plane.

According to some embodiments, for example, the thrust shaft support of the rotor is provided by a magnetic thrust bearing. This thrust bearing can be actively controlled, for example.

Each radial sensor assembly can, for example, detect radial displacement in two radial directions. The two radial directions can be, for example, right angles to each other. In general, each radial sensor assembly can have, for example, an inductive sensor system. Other sensor principles, such as capacitive sensors or optical sensors, are also feasible.

The present invention further comprises, in particular, a method of operating a vacuum pump, particularly a turbo molecular pump, according to the aforementioned embodiment, in which the rotor is pivotally supported by at least first and second radial bearings, the first radial bearing. , Actively controlled magnetic bearing. The first radial sensor assembly identifies the radial displacement of the rotor in the first axial region. The second radial sensor assembly identifies the radial displacement of the rotor in a second axial region that is different from the first axial region.

According to one embodiment, based on the measurements identified by the radial sensor assembly, the tilt of the rotor is compensated by impacting the rotor, for example, with an active controlled first radial bearing. ..

In general, all the features and embodiments described in relation to vacuum pumps can preferably be used to improve the way they operate and vice versa.

The present invention also relates to a method of calibrating a second radial sensor assembly of a vacuum pump of the aforementioned embodiment having the features described in the claims for a vacuum pump. This calibration method includes at least the following steps in which the rotor is displaced by a specific radius by the first radial bearing, the measurements are recorded by the second radial sensor assembly, and the second axial direction. The steps in which the actual displacement of the rotor in the region is known or identifiable depending on the displacement in the first axial region, and the measurements are associated with the actual displacement, thereby the pump. It has a step in which the displacement of the rotor in the second axial region can be estimated from the measured value of the second radial sensor assembly during operation.

Therefore, finally, calibration of the amplification factor of the measured value of the second radial sensor assembly is performed, which is performed by a particularly simple and reliable means.

According to some embodiments, the first radial bearing calibrates the first radial sensor assembly by a certain radius for the first time and / or prior to the displacement of the rotor. In doing so, for example, the rotor is pulled or displaced by the first radial bearing to a stopper or maximum value, which, for example, determines the amplification factor and / or offset of the sensor signal. The calibration of the first radial sensor assembly can be performed, for example, immediately before the calibration of the second radial sensor assembly, or at some point before that.

According to another embodiment, the rotor is radially displaced in more than one direction by the first radial bearing. Therefore, the second radial sensor assembly can be calibrated in multiple directions and by particularly simple means. Therefore, the control can be performed more accurately.

According to some embodiments, it is assumed that the rotor is displaced along a circular track by the first radial bearing. This allows for a particularly simple but accurate calibration of the second radial sensor assembly. The circular orbit can have, for example, a predetermined radius. The rotor can be displaced at a particular frequency along a circular trajectory. Specifically, the displacement along the circular orbit may also be referred to as "stirring motion".

According to one embodiment, it is assumed that the rotor does not rotate during calibration. For example, the rotor moves around the zero axis, for example, along a circular orbit. However, the rotor does not rotate, for example, in the circumferential direction, the rotor remains stationary or fixed. In general, the motor of the pump that drives the rotor can be turned off during calibration.

According to one embodiment, the actual displacement of the rotor in the second axial region can be calculated and specified based on the mechanical relationship, depending on the displacement in the first axial region. This particular basis may be, for example, the stiffness of the second thrust bearing, the inertia and geometry of the rotor, and the radius and frequency of shaft end displacement or excitation.

Depending on the calibration method, it is utilized, for example, that the mechanical relationships in the pump are well known, especially since the manufacturing accuracy is generally at a high level. Thus, the second radial sensor assembly can be precisely calibrated, for example, by comparing the known maximum displacement of the rotor with the measurements identified by the second radial sensor assembly, especially the voltage values.

This calibration method can also be referred to as dynamic calibration, unlike normal calibration of a single radial sensor assembly, which can also be referred to as static calibration.

Hereinafter, the present invention will be described with reference to the accompanying drawings based on preferred embodiments as examples.

The perspective view of the turbo molecular pump is shown. The bottom view of the turbo molecular pump of FIG. 1 is shown. The cross-sectional view of the turbo molecular pump along the cutting line AA shown in FIG. 2 is shown. The cross-sectional view of the turbo molecular pump along the cutting line BB shown in FIG. 2 is shown. The cross-sectional view of the turbo molecular pump along the cutting line CC shown in FIG. 2 is shown. The schematic diagram of the vacuum pump which concerns on this invention is shown. The radial sensor assembly is shown. Shows the displacement of the rotor during calibration.

The turbo molecular pump 111 shown in FIG. 1 has a pump inlet 115 surrounded by an inlet flange 113. A vacuum container (not shown) can be connected to the pump inlet 115 by a means known per se. The gas arriving from the vacuum vessel can be sucked from the vacuum vessel through the pump inlet 115 and pumped through the pump to the pump outlet 117. A pre-vacuum pump (eg, a rotary vane pump) may be connected to the pump outlet 117.

The inlet flange 113 forms the upper end of the housing 119 of the vacuum pump 111 in the direction of the vacuum pump of FIG. Housing 119 has a lower portion 121. An electronics housing 123 is arranged on the side of the lower portion 121. The electrical and / or electronic components of the vacuum pump 111 are housed within the electronics housing 123. These components are, for example, for operating an electric motor 125 arranged in a vacuum pump. The electronics housing 123 is provided with a plurality of connections 127 for accessories. In addition, a data interface 129 (eg, one conforming to the RS485 standard) and a current supply connection 131 are located in the electronics housing 123.

The housing 119 of the turbo molecular pump 111 is provided with a ventilation inlet 133, particularly in the form of a ventilation valve. The vacuum pump 111 can be ventilated through the ventilation inlet 133. A seal gas connection portion 135 (also referred to as a purge gas connection portion) is further arranged in the region of the lower portion 121. Through the seal gas connection portion 135, purge gas can be sent into the motor chamber 137 in order to protect the electric motor 125 (see, for example, FIG. 3) against the gas pumped by the pump. In the motor chamber 137, the electric motor 125 is housed in the vacuum pump 111. Two more coolant connecting portions 139 are arranged on the lower portion 121. In this case, one coolant connection is provided as an inlet for the coolant and the other coolant connection is provided as an outlet. The coolant can be introduced into the vacuum pump for cooling purposes.

Since the lower surface 141 of the vacuum pump can be used as a base, the vacuum pump 111 can be operated vertically on the lower surface 141. However, the vacuum pump 111 can also be fixed to the vacuum vessel via the inlet flange 113, so that it can be operated in a suspended state. Further, the vacuum pump 111 may be configured to operate even when it is oriented in a manner different from that shown in FIG. It is also possible to realize the form of a vacuum pump in which the lower surface 141 can be arranged sideways or upwards instead of downwards.

Various screws 143 are further arranged on the lower surface 141 shown in FIG. These screws secure the components of the vacuum pump, which are not specified here in detail, to each other. For example, the bearing cover 145 is fixed to the lower surface 141.

A fixing hole 147 is further arranged on the lower surface 141. The pump 111 can be fixed, for example, to the installation surface through the fixing holes 147.

2 to 5 show the coolant pipe 148. In the coolant pipe 148, the coolant introduced or derived via the coolant connecting portion 139 can be circulated.

As shown in the cross-sectional views of FIGS. 3-5, the vacuum pump has a plurality of process gas pump stages. These process gas pump stages are for pumping the process gas acting on the pump inlet 115 to the pump outlet 117.

A rotor 149 is arranged in the pump housing 119. The rotor 149 has a rotor shaft 153 that can rotate about the rotation axis 151.

The turbo molecular pump 111 has a plurality of pump stages connected in series with each other to exert a pumping action. These pump stages have a plurality of radial rotor disks 155 fixed to the rotor shaft 153 and a stator disk 157 arranged between the rotor disks 155 and fixed within the housing 119. In this case, one rotor disk 155 and one stator disk 157 adjacent thereto form one turbo molecular pump stage, respectively. The stator discs 157 are held by spacer rings 159 at desired axial spacing from each other.

The vacuum pumps also have Holbeck pump stages that are arranged in and out of each other in the radial direction and connected in series with each other to exert a pumping action. The rotor of the Holbeck pump stage has a rotor hub 161 located on the rotor shaft 153 and two cylindrical side surface Holbeck rotor sleeves 163,165 fixed to the rotor hub 161 and supported by the rotor hub 161. These Holbeck rotor sleeves 163 and 165 are coaxially oriented with respect to the axis of rotation 151 and are connected in and out of each other in the radial direction. Further, two Holbeck stator sleeves 167 and 169 having a cylindrical side surface are provided. These Holbeck stator sleeves 167,169 are similarly oriented coaxially with respect to the axis of rotation 151 and are connected to each other in and out of the radial direction.

The pumping surface of the Holbeck pump stage is formed by the sides, i.e., the radial inner and / or outer surfaces of the Holbeck rotor sleeves 163,165 and the Holbeck stator sleeves 167,169. The radial inner surface of the outer Holbæk stator sleeve 167 faces the radial outer surface of the outer Holbæk rotor sleeve 163, forming a radial Holbæk gap 171 and the Holbæk gap 171. At the same time, a first Holbek pump stage following the turbo molecular pump is formed. The radial inner surface of the outer Holbæk rotor sleeve 163 faces the radial outer surface of the inner Holbæk stator sleeve 169, forming a radial Holbæk gap 173, and this Holbæk gap 173. At the same time, a second Holbæk pump stage is formed. The radial inner surface of the inner Holbæk stator sleeve 169 faces the radial outer surface of the inner Holbæk rotor sleeve 165, forming a radial Holbæk gap 175, and this Holbæk gap 175. At the same time, a third Holbæk pump stage is formed.

The lower end of the Holbeck rotor sleeve 163 may be provided with a channel extending in the radial direction. Through this channel, the Holbæk gap 171 located on the outer side in the radial direction is connected to the central Holbæk gap 173. Further, the upper end of the inner Holbeck stator sleeve 169 may be provided with a channel extending in the radial direction. Through this channel, the central Holbæk gap 173 is connected to the Holbæk gap 175 located inward in the radial direction. As a result, a plurality of Holbeck pump stages connected to each other inside and outside are connected in series with each other. The lower end of the Holbeck rotor sleeve 165 located radially inward may further be provided with a connecting channel 179 leading to the outlet 117.

The surfaces of the Holbaek stator sleeves 163 and 165, each of which exerts the pumping action described above, have a plurality of Holbaek grooves extending in the axial direction while spirally orbiting around the rotation axis 151. On the other hand, the opposite sides of the Holbæk rotor sleeves 163,165 are smoothly formed and pump gas forward in the Holbæk groove for the operation of the vacuum pump 111.

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

In the area of the rolling bearing 181, a conical splash nut 185 is provided on the rotor shaft 153. It has an outer diameter that increases towards rolling bearing 181. The splash nut 185 is in sliding contact with at least one scraping member of the working medium reservoir. 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 rolling bearings 181 such as a lubricant.

During operation of the vacuum pump 111, the working medium is transmitted from the working medium storage to the rotating splash nut 185 via a scraping member by capillarity and along the splash nut 185 based on centrifugal force. , Splash nut 185 is pumped towards the rolling bearing 181 towards the increasing outer diameter. There, for example, the lubrication function is exerted. The rolling bearing 181 and the working medium storage portion are surrounded by a tank-shaped insert 189 and a bearing cover 145 in a vacuum pump.

The permanent magnet type magnetic bearing 183 has a bearing half portion 191 on the rotor side and a bearing half portion 193 on the stator side. They each have one ring stack, which consists of a plurality of rings 195,197 of permanent magnets stacked up and down in the axial direction. The ring magnets 195 and 197 face each other while forming a radial bearing gap 199. In this case, the ring magnet 195 on the rotor side is radially outward and the ring magnet 197 on the stator side is radial. It is located inside the direction. The magnetic field present in the bearing gap 199 causes a magnetic repulsive force between the ring magnets 195 and 197. The repulsive force provides radial support for the rotor shaft 153. The ring magnet 195 on the rotor side is supported by the support portion 201 of the rotor shaft 153. The support portion 201 surrounds the ring magnet 195 on the outer side in the radial direction. The ring magnet 197 on the stator side is supported by the support portion 203 on the stator side. The support portion 203 extends through a ring magnet 197 and is suspended on a radial support 205 of the housing 119. The ring magnet 195 on the rotor side is fixed by the cover element 207 connected to the support portion 203 in parallel with the rotation axis 151. The ring magnet 197 on the stator side is fixed by a fixing ring 209 coupled to the support portion 203 and a fixing ring 211 coupled to the support portion 203 in one direction parallel to the rotation axis 151. Further, a disc spring 213 may be provided between the fixing ring 211 and the ring magnet 197.

An emergency bearing or a safety bearing 215 is provided in the magnetic bearing. The emergency bearing or safety bearing 215 slips in a non-contact manner during normal operation of the vacuum pump and only engages when the rotor 149 is excessively displaced radially relative to the stator, thereby the rotor. Since the collision between the side structure and the stator side structure is prevented, a radial stopper with respect to the rotor 149 is formed. The safety bearing 215 is configured as a non-lubricated rolling bearing and forms a radial gap with the rotor 149 and / or the stator. This gap prevents the safety bearing 215 from engaging during normal pump operation. The radial displacement with which the safety bearing engages is sized sufficiently large that the safety bearing 215 does not engage during normal operation of the vacuum pump and is at the same time small enough so that the structure on the rotor side. Collision between the and the structure on the stator side is prevented in all situations.

The vacuum pump 111 includes an electric motor 125 that rotationally drives the rotor 149. The armature of the electric motor 125 is formed by a rotor 149. The rotor shaft 153 of the rotor 149 extends through the motor stator 217. Permanent magnet assemblies may be placed in portions of the rotor shaft 153 that extend through the motor stator 217, either radially outward or embedded. An intermediate chamber 219 is arranged between the motor stator 217 and the portion of the rotor 149 extending through the motor stator 217. The hollow chamber 219 has a motor gap in the radial direction. Through this motor gap, the motor stator 217 and the permanent magnet assembly transmit driving torque, so that they can magnetically influence each other.

The motor stator 217 is fixed in the motor chamber 137 provided for the electric motor 125 in the housing. Through the seal gas connection 135, the seal gas (also referred to as purge gas, which may be air or nitrogen, for example) can reach the inside of the motor chamber 137. Through the seal gas, the electric motor 125 can protect against the corrosive portion of the process gas, eg, the process gas. The motor chamber 137 can also be evacuated via the pump outlet 117. That is, the vacuum pressure realized by the pre-vacuum pump connected to the pump outlet 117 acts, at least approximately approximately, on the motor chamber 137.

A so-called labyrinth seal 223 known per se may be further provided between the rotor hub 161 and the wall portion 221 that defines the motor chamber 137. This achieves better sealing of the motor chamber 217, especially for the Holbeck pump stage located radially outward.

The vacuum pump according to the present invention according to FIG. 6 described below can be suitably improved by the individual characteristics of the vacuum pump described above.

FIG. 6 shows the vacuum pump 10 in a schematically significantly reduced view. The vacuum pump 10 has a rotor 12, which supports a plurality of turbo rotor discs 14 and can be rotationally driven by a motor 16 about a rotor axis 18 to a stator disc (not shown). The turbo rotor disc 14, which rotates relative to the other, causes a pumping action. In FIG. 6, the pumping action proceeds from top to bottom.

The rotor 12 is pivotally supported by a plurality of magnetic bearings. A first radial bearing 20 with respect to the rotor 12 is located at the outlet-side end of the rotor 12. 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 inlet side.

The first radial bearing 20 and the thrust bearing 22 are configured in an active control type. That is, these bearings can actively counter the radial or axial displacement of the rotor 12 from the ideal position of the rotor 12, for example via an electromagnet. Therefore, a radial sensor assembly 26 is arranged beside the radial bearing 20 so that the radial sensor assembly 26 allows the rotor 12 in the first axial region in two spatial directions perpendicular to the rotor axis 16. The radial displacement is measurable. Thrust sensor assemblies are provided as well, but are not shown.

The second radial bearing 24 is passively configured and does not have an actuator system that affects the rotor 12. Rather, the second radial bearing 24 has, for example, a plurality of permanent magnets on the rotor side and the stator side.

A second radial sensor assembly 28 is provided, which allows the displacement of the rotor 12 in the second axial region to be measured. In the present embodiment, the second radial sensor assembly is arranged not only between the first radial bearing 20 and the second radial bearing 24, but also between the motor 16 and the second radial bearing 24. ing. Therefore, the second radial sensor assembly 28 is fixed to the component 30 that defines the motor chamber 32 of the motor 16.

The first and second radial sensor assemblies 26, 28 are largely spaced apart from each other in the axial direction. Ideally, when these radial sensor assemblies measure different displacements of the rotor 12 in the corresponding axial region, the rotor 12 is tilted, i.e. the rotor axis 18 of the rotor 12 may also be referred to as the zero axis. It can be inferred that it is non-parallel to the rotor axis. As soon as the tilt is recognized, the active first radial bearing 20 can counter this tilt. Therefore, the first radial bearing 20 can exert an impact on the rotor 12, for example, to push the rotor 12 back to its upright position to some extent. This kind of control is comparable to that of an inverted pendulum. As the upper region of the rotor 12 begins to tilt, an impact is introduced into the rotor 12 on the lower side, which counteracts the tilt and, in the best case, causes the rotor 12 to stand upright, either directly or gradually. The rotor axis 18 is parallel to the zero axis. Moreover, for example, at the same time, not only the inclination is controlled, but also the radial position of the rotor is controlled as well. Tilt control and position control are particularly superposed on each other.

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.

The radial sensor assembly 34 has a ring-shaped board 36 to which a plurality of coils 38 are attached. The rotor whose displacement should be measured should have its rotor axis extending perpendicular to the plane through this ring. When the rotor is displaced, that is, slid along the plane of view in FIG. 7, this changes the interaction of the coils 38, resulting in a change in the measurement signal. That is, the displacement can be estimated from this measurement signal. In this case, two coils are provided on opposite sides of each other in each of the moving directions x and y.

FIG. 8 specifically shows a calibration method for the second radial sensor assembly 28 of, for example, the pump according to FIG. The rotor is here simply indicated by its rotor axis 18. The active first radial bearing 20 displaces the rotor to the stopper. At that time, the rotor axis 18 is inclined, that is, is oriented obliquely with respect to the zero axis 40. Displacements at the stoppers are known based on the mechanical relationships of the rotor system or can be identified alternative or additionally by, for example, the first radial sensor assembly 26. Of course, for the sake of concreteness, the displacement and tilt of the rotor axis 18 are shown with significant exaggeration.

The first radial sensor assembly 26 identifies, for example, the displacement 42 in the first axial region. At that time, the actual displacement 44 in the second axial region, that is, near the second radial sensor assembly 28, can be calculated based on the known mechanical relationships. In addition, the measurements are recorded by the second radial sensor assembly 28. The actual displacement 44 is associated with this. Therefore, since the amplification coefficient of the radial sensor assembly 28 is known, the displacement value can be estimated depending on the measured sensor voltage.

FIG. 8 further suggests a track 46, in which the rotor is moved along the track 46 by, for example, a first radial bearing 20 at a specific radius and a specific frequency for calibration purposes. Can be done. Therefore, all displacement directions of the radial sensor assembly 28 can be reliably calibrated.

In FIGS. 6 and 8, the first radial sensor assembly 26 is axially associated with the first radial bearing 20 and is located beside the first radial bearing 20. The second radial sensor assembly 28 is not axially associated with either the first radial bearing 20 or the second radial bearing 24, and instead is separated from both radial bearings 20, 24. It is arranged.

In FIG. 8, axial centers of the radial bearings 20 and 24 and the radial sensor assemblies 26 and 28 are suggested, respectively. A particular axial distance between these axial centers is associated with the letters a to d.

The axial distance a is defined by the axial distance between the axial center of the first radial sensor assembly 26 and the axial center of the first radial bearing 20. The axial distance b is defined by the axial distance between the axial center of the second radial sensor assembly 28 and the axial center of the second radial bearing 24. The ratio b / a is preferably at least 2, preferably at least 3.5, preferably at least 5, and preferably at least 7.

The distance c is defined by the axial distance between the axial center of the first radial bearing 20 and the axial center of the second radial bearing 24, in which case the axial central portion region of the distance c is defined. , Axial length d, in which case the second radial sensor assembly 28 is located within this partial region with its axial center, in which case the ratio d / c is preferably. Is 0.7, preferably 0.5, and preferably 0.4.

111 Turbo molecular 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 Ventilation inlet 135 Seal gas connection 137 Motor room 139 Coolant Connection 141 Bottom surface 143 Screw 145 Bearing cover 147 Fixing hole 148 Coolant piping 149 Rotor 151 Rotating axis 153 Rotor shaft 155 Rotor disk 157 Stator disk 159 Spacer ring 161 Rotor hub 163 Holbeck rotor sleeve 165 Holbeck rotor sleeve 167 169 Holbeck stator sleeve 171 Holbeck gap 173 Holbeck gap 175 Holbeck gap 179 Connection channel 181 Rolling bearing 183 Permanent magnet type magnetic bearing 185 Splash nut 187 Disc 189 Insert 191 Rotor side bearing half 193 Stator side bearing half 195 Ring Magnet 197 Ring magnet 199 Bearing gap 201 Support part 203 Support part 205 Radial support 207 Cover element 209 Support ring 211 Fixing ring 213 Countersunk spring 215 Emergency bearing or safety bearing 217 Motor stator 219 Intermediate chamber 221 Wall part 223 Labyrinth seal 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 40 Zero Axis 42 Displacement 44 Displacement 46 Circular Trajectory

Claims (15)

A rotor (12) that can be rotationally driven to exert a pumping action, and
The first and second radial bearings (20, 24) with respect to the rotor (12), the first radial bearing (20) is an active control type magnetic bearing, and the second radial bearing (20, 24). 24) includes first and second radial bearings (20, 24), which are configured as passive magnetic bearings.
A first radial sensor assembly (26) that identifies the radial displacement of the rotor (12) in the first axial region, and
A second radial sensor assembly (28) that identifies a radial displacement in a second axial region that is different from the first axial region.
A vacuum pump (10), particularly a turbo molecular pump. A rotor (12) that can be rotationally driven to exert pumping action,
The first and second radial bearings (20, 24) with respect to the rotor (12), and
Radius in the first radial sensor assembly (26) that identifies the radial displacement of the rotor (12) in the first axial region and in a second axial region that is different from the first axial region. A second radial sensor assembly (28) that specifies a displacement in the direction, wherein the first radial sensor assembly (26) is axially associated with the first radial bearing (20). And / or arranged beside the first radial bearing (20), the second radial sensor assembly (28) comprises the first radial bearing (20) and the second radial bearing (24). A first radial assembly (26) and a second radial sensor assembly (26) that are not axially associated with any of the) and / or are separated from both of the radial bearings (20, 24). 28) and
The vacuum pump (10), particularly according to claim 1. The axial distance a is defined by the axial distance between the axial center of the first radial sensor assembly (26) and the axial center of the first radial bearing (20).
The axial distance b is defined by the axial distance between the axial center of the second radial sensor assembly (28) and the axial center of the second radial bearing (24).
The ratio b / a is at least 2, preferably at least 3.5, preferably at least 5, and preferably at least 7.
The vacuum pump (10) according to claim 1 or 2. The second axial region is disposed between the first radial bearing (20) and the second radial bearing (24) and / or.
The distance c is defined by the axial distance between the axial center of the first radial bearing (20) and the axial center of the second radial bearing (24), and the axial direction of the distance c. The central partial region has an axial length d, the second radial sensor assembly (28) is located within the partial region with its axial center, and the ratio d / c is: It is preferably 0.7, preferably 0.5, and preferably 0.4.
The vacuum pump (10) according to any one of claims 1 to 3. The second axial region is located between the motor (16) for the rotor (12) and the second radial bearing (24) and / or.
At least one rotor element, preferably a plurality of rotor elements, preferably a turbo rotor element is provided between the second axial region and the second radial bearing (24) in the axial direction. Yes,
The vacuum pump (10) according to any one of claims 1 to 4. The vacuum pump (10) according to any one of claims 1 to 5, wherein a tilt control device is provided for the rotor (12). The vacuum pump (10) according to any one of claims 1 to 6, wherein the actuator system of the tilt control device is formed by the first radial bearing (20). The vacuum pump (10) according to claim 6 or 7, wherein the tilt control device is configured to compensate for the tilt of the rotor (12) by exerting an impact on the rotor (12). .. The second radial bearing (24) is arranged on the inlet side, and the first radial bearing (20) is arranged on the end of the rotor (12) opposite to the inlet of the pump. The vacuum pump (10) according to any one of claims 1 to 8. A method for calibrating the second radial sensor assembly (28) of the vacuum pump (10) according to any one of claims 1 to 9.
The rotor (12) is displaced by a specific radius (42) by the first radial bearing (20).
The measured value is recorded by the second radial sensor assembly (28).
The actual displacement (44) of the rotor (12) in the second axial region is known or identifiable depending on the displacement (42) in the first axial region.
The measured value is associated with the actual displacement (44), which allows the second axial region from the measured value of the second radial sensor assembly (28) during operation of the pump (10). The displacement of the rotor (12) in the above can be estimated.
A method of calibrating a second radial sensor assembly (28) of a vacuum pump (10). The method of claim 10, wherein the first radial sensor assembly is first calibrated. 10. The method of claim 10 or 11, wherein the rotor (12) is radially displaced in two or more directions by the first radial bearing (20). The method according to any one of claims 10 to 12, wherein the rotor (12) is displaced along a circular track (46) by the first radial bearing (20). The method according to any one of claims 10 to 13, wherein the rotor does not rotate during calibration. The actual displacement (44) of the rotor (12) in the second axial region is computationally identified based on mechanical relationships depending on the displacement (42) in the first axial region. The method according to any one of claims 10 to 14.

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