JP6998439B2 - Molecular vacuum pump - Google Patents

Description

The present invention comprises at least one molecular pump stage and one intermediate port, through which the gas can be transferred from the inlet to the outlet of the molecular vacuum pump, with the pump stage being one pump direction and the like. It relates to a molecular vacuum pump having one passage cross section lateral to the pump direction and an intermediate port located within the pump stage or downstream of the pump stage.

The passage cross section is an open surface in the pump stage within the cross section measured at selected points along the pump direction. That is, the passage cross section is particularly composed of the sum of the openings in the cross section through which the gas particles to be transferred can pass. For rotor actuated molecular vacuum pumps, the passage cross section extends perpendicular to the rotor axis, especially with respect to the cross section at selected points along the rotor axis.

An object of the present invention is to improve the discharge of gas existing in an intermediate port in such a vacuum pump, and / or to reduce the backflow of gas in a direction opposite to the pump direction starting from the intermediate port. Is.

The challenge is to place a preferably static blocking element in front of the intermediate port, especially in the pump direction, by the molecular vacuum pump with the features according to claim 1, which causes the passage cross section to be localized. It is solved by being reduced to.

The blocking element is a structurally simple method that reduces the backflow of gas to the area upstream of the intermediate port in the direction opposite to or in the direction of the pump starting from the intermediate port and present in the intermediate port. The pumping action against is improved. In particular, it has been found to be advantageous if the breaking element is a static element and / or is located in the stator of the pump. This is because structural changes are generally significantly more complex, especially based on dynamic forces in the rotor. That is, the present invention can be realized by modifying an existing pump without the need to change its rotor. However, basically, the blocking element can also be placed, for example, in the rotor.

The blocking element is placed especially just before the intermediate port. Thus, the blocking element can provide an advantageous guiding and / or shielding action for the gas or particle and / or give the particle a priority direction that extends at least in the pumping direction component. In general, the blocking element can constitute, for example, a guide and / or a shielding element.

The passage cross section of the pump stage is particularly one or more stator elements—especially in the case of turbo molecular pump stages—that is, one or more disposed upstream of the breaking element, especially in the pump direction. It is defined by the stator element. The pump stage can essentially have a passage cross section that changes along its axial spread. What is decisive is the local shrinkage before the intermediate port.

The local shrinkage or reduction of the passage cross-section is particularly formed such that the compression of the pump stage is locally increased in front of the intermediate port. In this case, the suction capacity can certainly be reduced locally in this area. However, for at least certain applications, this is justified in view of the improved pumping action for the gas present in the intermediate port. In general, the invention is particularly suitable for compression critical applications that do not require particularly high suction capacity at the main inlet, such as leak detectors.

The cross section of the passage is only reduced by the blocking element according to the invention, but not completely blocked. That is, the blocking element can cover, for example, a part of the cross section of the passage. Therefore, it remains possible to transfer the gas to the next pump stage via the pump stage next to the shutoff element. That is, the reduced passage cross section specifically connects the pump stage to the axial region of the intermediate port and / or to another pump stage specifically arranged in series downstream of the intermediate port and / or the pump stage. ..

In general, the intermediate port can be located, for example, particularly axially, within the pump stage, between a first portion of the pump stage and a second portion located downstream in series with the pump stage. .. Optionally, the intermediate port can be located, for example, especially axially downstream of the pump stage and especially upstream of the second pump stage arranged downstream in series. That is, the pump stage or the portion of the pump stage can generally be connected in particular in series. The pump stage or portion specifically comprises a rotor or rotor portion located on a common rotor shaft.

The passage cross section is particularly composed of an open area of cross section through the rotor of the pump within the area of the pump stage. In the case of a turbomolecular pump or a turbomolecular pump stage, the passage cross section of the turbostator disk is limited, for example, in the radial outward direction by the radial outer boundary of the turbostator blade. In this case, inwardly, the passage cross-section is limited by the radial inner boundaries of the turbostator blades, i.e., the so-called blade base. The passage cross section comprises an open portion separated by a blade in the circumferential direction. The same applies to turbo rotors or turbo rotor discs. In the case of a Holbeck pump, the cross section of the passage is restricted, for example, outward or inward by the bottom of each of the plurality of Holbeck grooves. In the opposite direction, i.e. inward or outward, the passage cross-section is restricted by the Holbeck rotor. The aisle cross section comprises an open portion separated by a web in the circumferential direction, the web separating the Holbeck groove. In general, the passage cross-sections in the Holbeck pump stage particularly substantially correspond to the sum of the cross-sections of the Holbeck grooves.

In particular, the aisle cross-section is at least 20%, in particular, with respect to the cross-sectional area of the aisle cross-section of the pump stage before and / or after the intermediate port-especially upstream stator disk in the case of turbo molecular pumps-due to the blocking element. It can be reduced by 30%.

The intermediate port of the multi-stage molecular pump is also referred to as, for example, an "interstage port", and the molecular pump provided with such an intermediate port is also referred to as a "split flow vacuum pump".

In particular, the cross section of the passage can be asymmetric locally, especially with respect to the rotor axis of the pump stage, due to the blocking element. For example, the cutoff element can be arranged on the side of the intermediate port of the rotor shaft of the pump stage such that the cutoff element blocks a greater proportion of the passage cross section than on the side opposite the intermediate port of the rotor. Generally preferably, the blocking element can be located on the side of the intermediate port of the rotor shaft. For example, the cutoff element can only be placed in the partial angle region with respect to the rotor axis, especially associated with the intermediate port. The blocking element can block the passage cross section in the region located between the rotor shaft and the intermediate port, especially in the radial direction. In general, the placement of the blocking element at the intermediate port causes, in addition to the reduced backflow from the intermediate port, a reduction in the probability that gas molecules will flow out of the upstream pump stage through the intermediate port.

For example, it can be attempted that the blocking element is opaquely formed at least within the circumferential portion associated with the intermediate port, particularly substantially only within this circumferential portion. The region radially opposed to the intermediate port may be particularly free from the blocking element, or the joint furnace cross section may be free. Within the region radially facing the intermediate port, the stator can be formed, especially in a transparent manner, generally like a "normal" stator. Generally preferably, the blocking element can extend over at least the angular region of the intermediate port and / or the circumferential region that coincides up to 180 °. Within this circumferential portion, the passage cross-section can be completely or particularly partially blocked by the blocking element.

The shape of the blocking element can be changed, for example. Therefore, different performances can be set for the backflow from the intermediate port and the pump stage in the pump direction, depending on the shape selected.

According to one embodiment, it is contemplated that the blocking element is formed as a wall and / or a continuous surface element and / or extends laterally with respect to the pump direction. This constitutes a structurally simple possibility of achieving the benefits of the present invention. The breaking element can extend vertically and / or laterally, especially with respect to the pump direction and / or the rotor axis. The face element or wall can be placed, for example, parallel to the boundary of the intermediate port and / or diagonally or perpendicular to the rotor axis.

In some embodiments, the blocking element extends radially only over a portion of the passage cross section of the pump stage, which is particularly adjacent, especially upstream and after the local reduction. / Or regarding the cross section of the passage downstream. In particular, the blocking elements can extend, for example, only over a radial portion of the passage cross section, each with less compression than the other. The radial region freed from the blocking element has a particularly high compression, but in some cases a slight suction capacity. High compression encourages slight regurgitation, otherwise the blocking element also reduces regurgitation. In particular, the blocking element can cover the inner part in the radial direction and / or not the outer part in the radial direction. For example, it can be combined with a blocking element in another circumferential region or part of the same blocking element that extends over the entire radial width.

According to one embodiment, the pump stage is a turbo molecular pump stage. The turbo molecular pump stage may include, for example, one or more turbo rotor discs and / or one or more turbo stator discs. The intermediate port can be located, for example, downstream of the last turbostator disk or turborotor disk in the pump direction of the turbomolecular pump stage, especially the pump stage. Optionally, the intermediate port can be located, for example, at an axially high position on one turbo rotor disk, or merge into such a location, i.e., generally within the pump stage.

According to one embodiment, it is contemplated that the blocking element is formed as part of a turbostator disc. Basically, the blocking element can be attached directly to, for example, a stator disc, in particular a partial stator disc, and / or axially attached to such a disc. Axial attachment means that the blocking element is located in at least partially the same axial region as the stator disk or partial stator disk. In particular, the cutoff element can replace a portion of the turbostator disk on the side of the intermediate port. In terms of cross-section and axial height of the blocking element, for example, a stator blade can be provided on one side of the rotor shaft, especially opposite to the intermediate port, but on the other side of the intermediate port of the rotor shaft. Is provided with a blocking element, and is not particularly provided with a stator blade.

The blocking element can be formed as a sheet metal according to a structurally simple embodiment. Turbo stator discs are often similarly formed as sheet metal portions, and blocking elements can generally be manufactured or formed similar to turbostator discs, but are not specifically provided with separate blades.

In the advanced form, the blocking element is intended to define a blade base specifically for the inner inside of some or all of the turbostator discs. In particular, the blade base diameter defined by the blocking element can be larger than the blade base diameter of the upstream rotor disk and / or stator disk, especially by at least 20%.

The blocking element can be formed, for example, in a petri dish and / or funnel shape, in particular a partial ring shape, a partial petri dish shape and / or a partial funnel shape, and the term "partial" is particularly centered on the rotor shaft. Refers to the angle area to be. Such blocking elements can be specifically placed between two spaced disc packs and / or pump stages.

Another embodiment contemplates that the pump stage is a Holbeck pump stage.

The blocking element can preferably be formed as at least one Holbeck groove or a side wall of a Holbeck passage. In general, the blocking element can extend perpendicular to, for example, a groove or passage, pump direction or rotor axis. In the following, for the sake of simplicity, only the Holbeck groove will be referred to, but it is understood that each feature is generally valid for the Holbeck passage as well.

According to the evolution, it is intended that at least one web that laterally restricts the Holbeck groove will have a gap for the intermediate port in the area downstream of the intermediate port in the pump direction. That is, the web does not reach the intermediate port, especially in the direction opposite to the pump direction, that is, it does not have a total height at least in its radial direction, and the web edge is separated from it. The voids facilitate gas entry from the intermediate port of the Holbeck pump stage to the downstream portion of the intermediate port in the pump direction by providing good conductance for the gas.

For other developments, it is contemplated that at least one web that laterally restricts the Holbeck groove will have a gap for the intermediate port in the region upstream of the blocking element in the pump direction. This void allows the gas particles to be transferred to reach the next Holbeck groove from one Holbeck groove along the blocking element. Therefore, the Holbeck groove with the blocking element is not blocked in the pump direction in the sense of a dead end, but the pumping action of the Holbeck groove in the region upstream of the blocking element causes the particles to pass through the void to the next Holbeck groove. It can be further utilized by being able to reach and be pumped further there. Thus, in particular, the probability that each particle will reach the intermediate port from the Holbeck groove through between the blocking element and the Holbeck rotor is reduced, thereby avoiding cross-flow from the main inlet or Holbeck groove to the intermediate port. To. The gap connects a particularly blocked groove with the next groove in the direction of rotation of the Holbeck rotor, which also provides a corresponding gap to the next groove until it reaches the groove passing through the intermediate port. be able to.

Basically, an intermediate port can have its boundaries extending across multiple Holbeck grooves and / or attached to multiple Holbeck grooves. In an advantageous embodiment, an intermediate port is provided with its boundary attached to only one Holbeck groove. In this case, the attachment is seen at the point where the intermediate port joins the Holbeck groove. The intermediate port is basically configured in the Holbeck stator by the groove bottom opening there. In this case, the bottom of the Holbeck groove attached to the intermediate port is open. The opening extends over a plurality of Holbeck grooves if the intermediate port is attached multiple times, and extends into only one Holbeck groove if the intermediate port is attached once. The boundary of the intermediate port can be provided, in particular, only within one Holbeck groove. However, it is also possible that, essentially, the boundary extends into the web area and / or the web has a horizontal notch that defines the boundary.

Optionally or additionally, the intermediate port can be oriented, for example, at least one boundary and / or one longitudinal spread parallel to one Holbeck groove. Basically, the intermediate port can be oriented with at least one boundary perpendicular and / or parallel to the rotor axis.

In a preferred embodiment, the intermediate port has its boundaries attached to at least one first Holbeck groove and not to the next at least one second Holbeck groove in the direction of rotation of the Holbeck rotor. It is intended that the web between the first and second Holbeck grooves will be provided with a notch connecting the intermediate port to the second Holbeck groove. The notch can be placed specifically adjacent to and / or within the axial region of the intermediate port. For example, the blocking element can be formed as a lateral wall of the first Holbeck groove. In particular, the particles are free to enter the first Holbeck groove in the pump direction from the intermediate port. The blocking element blocks the entry of particles into the first Holbeck groove, especially in the direction opposite to the pump direction. The notch allows the particles to enter the Holbeck groove of 2 particularly freely, especially with moving components in the pump direction at least.

One of the first Holbeck grooves or generally Holbeck grooves bordered by the intermediate port is generally opposite to the direction of rotation of the Holbeck rotor, generally by at least the web in the axial region of the intermediate port. In the direction it can be separated from the next, especially the third Holbeck groove.

In general, a plurality of intermediate ports may be provided in one pump stage or between a plurality of pump stages, particularly between Holbeck pump stages and / or turbomolecular pump stages or between these pump stages. In general, the pump can preferably include a plurality of particularly different types of pump stages connected in series.

More generally, the pump can include a pump active rotor portion upstream of the intermediate port with respect to the pump direction and a pump active rotor portion downstream with respect to the pump direction, in particular both rotor portions are coupled to the same rotor shaft. And / or can be connected in series. In general, a vacuum pump can include, for example, only one rotor shaft, in particular all pump stages and pump stage portions can be driven by this rotor shaft and / or connected in series.

In general, the intermediate port preferably opens into the axial region, especially the pump housing, over which the pump stage or pump stage portion upstream of the intermediate port is the pump stage or pump stage downstream of the intermediate port. It is connected in series with the part. This axial region can be, for example, an intermediate stage region or an axial region within one pump stage, eg, an axial region of a turbo rotor disk. In general, the transfer of gas can be carried out, in particular, over the axial region and / or the intermediate stage region where the intermediate port opens. In particular, the blocking element is passed by gas in the pump direction through the remaining passage cross section.

According to another embodiment, it is contemplated that the blocking element and / or the stator element located at the intermediate port and with the blocking element is manufactured by a production process, particularly 3D printing. This allows for sufficiently free and appropriate formation of the blocking element in view of its blocking action, so that the advantages of the present invention can be effectively achieved by simple means. The production manufacturing method is understood as the manufacturing or modeling of parts by joining volume elements, for example, by stratification. Preferably, the production method is such that the component is at least one of stereolithography, laser melting, laser sintering, selective laser sintering, layer lamination, extrusion, fused deposition modeling, thin film lamination or 3D printing. Including being manufactured by laser.

Hereinafter, the present invention will be exemplified by an advantageous embodiment associated with the accompanying drawings.

Perspective view of turbo molecular pump Lower view of the turbo molecular pump of FIG. Cross-sectional view of the turbo molecular pump along the cutting line AA shown in FIG. Cross-sectional view of the turbo molecular pump along the cutting line BB shown in FIG. Cross-sectional view of the turbo molecular pump along the cutting line CC shown in FIG. Conventional turbomolecular pump with intermediate port Spacer ring for turbo molecular pump Turbo molecular pump according to one embodiment of the present invention Turbo molecular pump according to another embodiment Plan view of a normal turbo stator disc Top view of breaking element for turbo molecular pump stage Plot of compression of turbostator disk depending on radial position One embodiment of the blocking element Known Holbeck pump stage stator Holbeck pump stage stator according to one embodiment of the present invention Holbeck pump stage stator according to another embodiment

The turbo molecular pump 111 shown in FIG. 1 has a pump inlet 115 surrounded by an inlet flange 113, to which, as is well known per se, a recipient (not shown) can be connected. Gas from the recipient is drawn from the recipient through the pump inlet 115 and can be transferred through the pump to the pump outlet 117, to which a preliminary vacuum pump, such as a rotary vane pump, is connected. be able to.

The inlet flange 113 constitutes the upper end of the housing 119 of the vacuum pump 111 when the vacuum pump is oriented according to FIG. The housing 119 has a lower portion 121, and an electronic device housing 123 is arranged next to the lower portion. The electrical and / or electronic components of the vacuum pump 111 are housed in the electronic device housing 123, for example, to operate the electric motor 125 arranged in the vacuum pump. The electronic device housing 123 is provided with a plurality of ports 127 for accessories. In addition, for example, a data interface 129 and a power supply port 131 according to the RS485 standard are arranged in the electronic device housing 123.

The housing 119 of the turbo molecular pump 111 is provided with a filling inlet 133 in the form of a filling valve, and the vacuum pump 111 can fill the filling through the filling inlet. Furthermore, in the region of the lower portion 121, a seal gas port 135, which is also called a scavenging gas port, is arranged, and the scavenging gas is transferred from the gas transferred by the pump through the scavenging gas port to the electric motor 125 (see, for example, FIG. 3). The electric motor 125 can be introduced into the motor space 137-in which the electric motor 125 is housed in the vacuum pump 111-to protect. Furthermore, two coolant ports 139 are arranged in the lower portion 121, one of these coolant ports is provided as an inlet for the coolant, and the other coolant port is provided as an outlet for the coolant. This coolant can be introduced into the vacuum pump for cooling.

Since the lower side 141 of the vacuum pump can be used as a stand surface, the vacuum pump 111 can be operated while standing on the lower side 141. However, the vacuum pump 111 may be fixed to the recipient via the inlet flange 113 and thereby operated in a suspended state to some extent. In addition, the vacuum pump 111 can be configured to operate even when oriented differently than that shown in FIG. It is also possible to realize an embodiment of a vacuum pump in which the lower side 141 can be arranged sideways or oriented so as to face up instead of facing down.

Further, various bolts 143 are arranged on the lower side 141 illustrated in FIG. 2, and these bolts fix the parts of the vacuum pump, which are not further specified here, to each other. For example, the bearing cover 145 is fixed to the lower side 141.

In addition, a fixing hole 147 is arranged on the lower side 141, and the pump 111 can be fixed to, for example, a mounting surface through these fixing holes.

FIGS. 2 to 5 show a cooling agent line 148, in which a cooling agent introduced and derived can be circulated through the cooling agent port 139.

As shown in the cross-sectional views of FIGS. 3-5, the vacuum pump has a plurality of process gas pump stages for transferring the process gas present at the pump inlet 115 to the pump outlet 117.

A rotor 149 is arranged in the housing 119, and the rotor includes a rotor shaft 153 that can rotate about a rotation shaft 151.

The turbo molecular pump 111 has a plurality of radial rotor disks 155 fixed to the rotor shaft 153 and a stator disk 157 disposed between the rotor disks 155 and fixed to the housing 119, effectively in series with the pump. It has multiple turbo molecular pump stages interposed in it. In this case, the rotor disk 155 and the adjacent stator disk 157 each form one turbo molecular pump stage. The stator discs 157 are held by spacer rings 159 at desired axial spacing from each other.

In addition, the vacuum pumps are radially spaced from each other and have Holbeck pump stages effectively interspersed with each other in the pump. The rotor of the Holbeck pump stage has one rotor hub 161 located on the rotor shaft 153 and two cylinder shell shaped Holbeck rotor sleeves 163, 165 fixed to and supported by the rotor hub 161. These Holbeck rotor sleeves are coaxially oriented with respect to the rotation shaft 151 and are nested with each other in the radial direction. Further, two cylinder shell-shaped Holbeck stator sleeves 167 and 169 are provided, and these Holbeck stator sleeves are also coaxially oriented with respect to the rotation shaft 151 and are nested with each other when viewed in the radial direction. Has been done.

The pump active surface of the Holbeck pump stage is composed of shell surfaces, i.e., radial inner and / or outer surfaces, Holbeck rotor sleeves 163,165 and Holbeck stator sleeves 167,169. The radial inner surface of the outer Holbeck stator sleeve 167 faces the radial outer surface of the outer Holbeck rotor sleeve 163 while forming a radial Holbeck gap 171 with this radial outer surface of the turbomolecular pump. It constitutes the first Holbeck pump stage that follows. The radial inner surface of the outer Holbeck rotor sleeve 163 faces the radial outer surface of the inner Holbeck stator sleeve 169, forming a radial Holbeck gap 173, and together with this radial outer surface, a second Holbeck pump. Make up the steps. The radial inner surface of the inner Holbeck stator sleeve 169 faces the radial outer surface of the inner Holbeck rotor sleeve 165 while forming a radial Holbeck gap 175, along with this radial outer surface of the third Holbeck pump. Make up the steps.

At the lower end of the Holbeck rotor sleeve 163, a radially extending passage can be provided that connects the Holbeck gap 171 located radially outward by its intervention to the central Holbeck gap 173. In addition, a radially extending passage can be provided at the upper end of the inner Holbeck stator sleeve 169 to connect the central Holbeck gap 173 to the radial inwardly located Holbeck gap 175 by its intervention. .. As a result, the Holbeck pump stages nested in each other are interposed in series with each other. Further, a connecting passage 179 to the outlet 117 can be provided at the lower end of the Holbeck rotor sleeve 165 located inward in the radial direction.

The pump-active surfaces of the Holbeck stator sleeves 163 and 165 each include a plurality of Holbeck grooves spirally extending axially about the rotation shaft 151, but the opposite shells of the Holbeck rotor sleeves 163 and 165. The surface is formed smooth and propels the gas for operating the vacuum pump 111 in the Holbeck groove.

In order to rotatably bearing the rotor shaft 153, a rolling bearing 181 is provided in the region of the pump outlet 117 and a permanent magnet bearing 183 is provided in the region of the pump inlet 115.

In the area of rolling bearing 181 the rotor shaft 153 is provided with a conical spray nut 185 having an outer diameter that increases towards rolling bearing 181. The spray nut 185 is in sliding contact with at least one wiper of the working medium accumulator. The working medium accumulator has a plurality of hygroscopic discs 187 stacked one above the other, and these discs absorb a working medium for the rolling bearing 181 such as a lubricant.

During operation of the vacuum pump 111, the working medium is transmitted from the working medium accumulator to the rotating spray nut 185 via the wiper by capillary action, and due to centrifugal force, the outer diameter of the spray nut 185 along the spray nut 185. Is transferred towards the rolling bearing 181 in the increasing direction, where the working medium satisfies, for example, the lubrication function. The rolling bearing 181 and the working medium accumulator are surrounded by a tub-shaped insert 189 and a bearing cover 145 in a vacuum pump.

The permanent magnet bearing 183 has a bearing half body 191 on the rotor side and a bearing half body 193 on the stator side, and these bearing half bodies consist of a plurality of permanent magnet rings 195 and 197 stacked vertically vertically, respectively. It has one ring stack. The ring magnets 195 and 197 face each other while forming a radial bearing gap 199, the ring magnet 195 on the rotor side is arranged on the outer side in the radial direction, and the ring magnet 197 on the stator side is arranged on the inner side in the radial direction. ing. The magnetic field present in the bearing gap 199 causes a magnetic repulsive force between the ring magnets 195 and 197 that causes the radial bearing of the rotor shaft 153. The ring magnet 195 on the rotor side is supported by a carrier portion 201 of the rotor shaft 153, which surrounds the ring magnet 195 from the outside in the radial direction. The stator-side ring magnet 197 is supported by a stator-side carrier portion 203, which extends through the ring magnet 197 and is suspended by a radial brace 205 of the housing 119. Parallel to the rotation shaft 151, the ring magnet 195 on the rotor side is fixed by a cover element 207 connected to the carrier portion 203. The ring magnet 197 on the stator side is fixed in one direction in parallel with the rotation shaft 151 by a fixing ring 209 coupled to the carrier portion 203 and a fixing ring 211 coupled to the carrier portion 203. In addition, a disc spring 213 can be provided between the fixed ring 211 and the ring magnet 197.

An emergency or safety bearing 215 is provided within the magnetic bearing, which idles without contact during standard operation of the vacuum pump 111, with the rotor 149 relative to the stator being excessive. Only when radially displaced to engage to form a radial stopper for the rotor 149. This is because the collision between the structure on the stator side and the structure on the rotor side is prevented. The safety bearing 215 is formed as an unlubricated rolling bearing and, together with the rotor 149 and / or the stator, constitutes a radial gap that causes the safety bearing 215 to be released during standard pump operation. The radial displacement in which the safety bearing 215 engages is large enough so that the safety bearing 215 does not engage during standard operation of the vacuum pump, while at the same time colliding between the structure on the stator side and the structure on the rotor side. Is set small enough to prevent under all circumstances.

The vacuum pump 111 has an electric motor 125 for rotationally driving the rotor 149. The anchor of the electric motor 125 is composed of a rotor 149, and the rotor shaft 153 of the rotor extends through the motor stator 217. A permanent magnet device can be arranged in the portion of the rotor shaft 153 extending through the motor stator 217 on the outer side in the radial direction or embedded in the portion. An intermediate space 219 is arranged between the motor stator 217 and the portion of the rotor 149 extending through the motor stator 217, the intermediate space having a radial motor gap through which the motor The stator 217 and the permanent magnet device can be magnetically affected to transmit the drive torque.

The motor stator 217 is fixed in the housing in the motor space 137 provided for the electric motor 125. Through the seal gas port 135, a seal gas, also called scavenging gas, which can be, for example, air or nitrogen, can reach into the motor space 137. Through the seal gas, the electric motor 125 can be protected from the process gas, for example, the corrosive action component of the process gas. The motor space 137 can also be evacuated through the pump outlet 117, i.e., the inside of the motor space 137 is at least largely dominated by the vacuum pressure generated by the preliminary vacuum pump connected to the pump outlet 117.

In addition, it is well known between the rotor hub 161 and the wall 221 that defines the motor space 137, in particular to achieve good sealing of the motor space 217 for the Holbeck pump stage located radially outward. The so-called labyrinth seal 223 can be provided.

The pumps and systems described below are illustrated in a partially significantly schematic simplification. They can advantageously be implemented with the individual or multiple features of the pump for practical implementation.

FIG. 6 shows a vacuum pump 20 formed as a turbo molecular vacuum pump. The schematic shows a rotor shaft 22 in which a plurality of turbo rotor discs 24 are coupled and rotate together with the turbo rotor discs 24 here about a vertical rotor axis during operation. A turbo stator disc 26 is provided between the turbo rotor discs 24. Both of these give rise to the transfer of gas along the pump direction 28, indicated here by the arrow.

The vacuum pump 20 has an intermediate port 30 which is simplified here and is shown as an arrow. The intermediate port 30 is located approximately at one axial height position of the turbo rotor disk 24, i.e., is open to that axial or effective region.

FIG. 6 does not show the turbo stator disk 26 downstream of the intermediate port 30 in the pump direction. However, it can be seen that the turbo stator disc 26 can also be provided there.

A known stator disk 24 is arranged upstream of the intermediate port 30 in the pump direction 28. Although the pump 20 is transferred in the pump direction 28, it is possible to some extent that the gas particles present in the intermediate port 30 move in the direction opposite to the pump direction 28 after entering the vacuum pump 20. In this case, the particles may pass through the turbostator disk 26 upstream of the intermediate port 30, or may basically pass through another turborotor disk 24 and a turbostator disk 26. Therefore, some backflow 32 is generated here, as indicated by the arrows.

FIG. 7 shows a spacer ring 34 that can be provided, for example, to support two turbostator discs 26 apart from each other. The spacer ring 34 comprises a notch 36 that defines a boundary for one of the intermediate inlets, eg, the intermediate inlet 30 or one of the intermediate inlets described below.

It is an object of the present invention to reduce the backflow 32. In general, gas should be discharged from intermediate port 30 as well as possible and / or should not flow back. In this case, it may not be desirable to change the structure of the rotor, especially the turbo rotor disk 24. If possible, the existing rotor structure should be sustainable. The present invention specifically seeks an approach that increases the internal compression between the intermediate port and the main inlet, i.e., the first inlet in the pump direction, and in particular makes structural changes in static components.

Evaluation of the measurements showed that the distribution of inflows had a significant effect on further backflow. Mostly, for the types of intermediate ports discussed here, the gas flows radially with respect to the rotor disk, as in FIG. For example, if the stator disk located upstream is covered by a blocking element, such as a partial petri dish, especially a semi-Petri dish or a partial ring, especially a half-ring, within the angular region associated with the intermediate port, significantly less gas will flow back. Can be guided downstream in the turbo disc pack. Such an approach is illustrated in FIGS. 8, 9 and 11.

In FIG. 8, the vacuum pump 20 formed as a turbo molecular pump is shown in the same representational form as in FIG. 6, with reference numerals being used accordingly. A blocking element 38 is provided upstream of the intermediate port 30 in the pump direction 28. It is formed, for example, as a continuous surface or wall and extends only over the partial angular region of the rotor shaft 22. A turbostator disk 26 is provided in the remaining partial angle region of the axial region.

The blocking element 38 prevents backflow 32 as shown in FIG. The movement of the particles is indicated by the arrow 40 here. Such particles that initially move from the intermediate port 30 in the direction opposite to the pump direction 28 collide with the blocking element 38 and cannot move any further in the direction opposite to the pump direction 28. After withdrawal from the blocking element 38, each particle basically has a statically distributed direction of travel, which extension is particularly extended with a component at least in the pump direction 28. That is, the blocking element 38 reduces the probability that each particle will move in the vacuum pump 20 in the direction opposite to the pump direction.

The turbostator disk 26 is formed permeable in the axial direction, i.e., in the pump direction, and yet does not allow the particles to fly exactly axially, but between the stator blades where the axial transfer of gas is positioned. It is formed as it is possible through. That is, the turbo stator disk 26 has a passage cross section. The passage cross section of the turbostator disk 26 is here constant over the axial spread of the only turbomolecular pump stage 41, except for the axial region where the cutoff element 38 is located. The blocking element 38 is formed opaque and / or closed, thus reducing the passage cross-section of the pump stage in the pump direction 28 within the locally restricted axial region, i.e. just before the intermediate port 30. do.

It should be noted that the breaking element 28 is shown here significantly thicker than the turbo stator disc 26. However, this is used, for example, for distinguishable representations. In practice, the blocking element 38 can be formed, for example, as a particularly thin sheet metal, especially thinner than the stator disc 26.

The vacuum pump 20 of FIG. 9 includes two axially spaced disc packs constituting a first turbo molecular pump stage 42 and a second turbo molecular pump stage 44. Between the pump stages 42 and 44, there is an intermediate stage region 46 in which the intermediate port 30 opens. Unlike in FIG. 8, the intermediate port 30 is here, exemplary, not in the turbo rotor disk 24, but in the free space between the pump stages 42 and 44. This is advantageous in view of the conductance and suction capacity at the intermediate port 30, and may be used especially when a large effective suction capacity is desired and / or where the conductance within the region of the intermediate port 30 should be high. can.

In this case, the blocking element 38 can be oriented obliquely with respect to the rotor shaft or shaft and / or the pump direction 28, for example with respect to the longitudinal section. Basically, the blocking element 38 can act as a guide element, especially as a guide plate. Therefore, the particles can be guided in the pump direction 28 particularly advantageously.

For example, the cutoff element 38 according to FIG. 8 or FIG. 9 is arranged, for example, on the side of the rotor shaft or the intermediate port 30 of the rotor shaft 22 and / or in the angular region with respect to the rotor shaft associated with the intermediate port 30. Can be formed as a partial ring, especially a half ring.

FIG. 10 typically shows, for example, one of the upper turbostator discs 26 in FIGS. 8 and 9 or one of the three illustrated turbostator discs 26 in FIG. The turbo stator disc 26 is shown. The turbo stator disk 26 of FIG. 10 is shown in plan view, and the gaze direction extends parallel to the pump direction and the rotor axis. The turbostator disk 26 has a plurality of turbostator blades 48 distributed and arranged around the turbostator disc 26, and particles of gas to be transferred can pass between the turbostator blades 48. Thus, the intermediate space between the turbo stator blades 48 constitutes the passage cross section, provided that the intermediate space is not only configured here by the free area between the visible stator blades 48, but here. Then, due to the angle of attack of the invisible stator blade 48, it partially extends below or above the stator blade 48.

In FIG. 11, a viewpoint similar to that in FIG. 10 is selected and the turbostator disc 26 is seen, but the turbostator disc here fills only the partial angle region. The remaining partial angle region is shielded by the blocking element 38. An intermediate port 30 is shown and a blocking element 38 is provided upstream of the intermediate port 30 in the pump direction. That is, the pump direction here extends towards the gaze person.

The blocking element 38 is formed as a continuous surface element, for example, a sheet metal. The blocking element constitutes a partial ring in this embodiment, which here schematically extends over about 180 ° around the rotor axis.

The blocking element 38 itself has no passage cross section or is formed impermeable. Therefore, the passage cross section of the pump stage is reduced locally in the axial region illustrated herein, i.e., to an angular region where the blocking element 38 is not exemplary or shielded.

As can be better seen in FIG. 11, the passage cross section is here particularly locally asymmetric with respect to the rotor axis. On the side of the intermediate port 30 of the rotor shaft, the blocking element 38 blocks a larger proportion of the passage cross section than on the side opposite the intermediate port 30 of the rotor. The angular region covered by the blocking element 38 is particularly arranged such that the intermediate port 30 is at least substantially centered in the angular region.

The blocking element 38 according to FIG. 11 can be formed, for example, in relation to the vertical section according to FIG. 8 or FIG. In particular, the blocking element 38 can be formed, for example, as a flat surface element and / or extend perpendicular to the rotor axis. Optionally, the blocking element 38 can be tapered, eg, in a partial funnel and / or a partial dish, in particular as a semi-funnel or semi-dish. In general, the blocking element 38 can be formed, in particular, in a partial ring shape.

Essentially, the blocking element 38 can cover, for example, a standard turbostator disc as in FIG. 10 or otherwise replace a corresponding cross-sectional area. In the latter case, a partial stator disk 26 is provided in particular, and the partial stator disk is particularly axially attached to the cutoff element 38 and / or the cutoff element.

Another approach to reducing backflow is to use a stator disk within the section, which has a particularly high compression and thus has a sealing effect. In FIG. 12, the compression process for a typical turbostator disk is qualitatively plotted along the radial spread of each turbostator blade. The horizontal axis represents the radius R at the position in the radial direction, and the vertical axis represents the compression K. Here, the curve illustrated by the simplified straight line indicates that the compression K is maximum in the radial outer region 49.

For example, only the radial outer region 49 of the stator disk can be used. This region contains only particles with very large momentum, but is a region with high compression. In contrast, regions located inwardly in the radial direction have lower compression, especially due to their lower peripheral speed. That is, preferably, only high compression is allowed by utilizing a predetermined radial region.

The relationship shown in FIG. 12 is utilized in the embodiment of FIG. Here, the blocking element 38 covers a region inside the rotor blade 48 in the radial direction, where it is assumed that the stator disk 26 is otherwise configured as shown in FIG. However, basically, the stator blade 48 does not need to extend into the radial region of the blocking element 38. Rather, here advantageously the cutoff element 38 provides a passage cross section with an inner diameter that is locally greater than the passage cross section of the other passage cross section of the pump stage or the upstream turbo rotor disk or turbo stator disk. It should be shown to be scaled down to a surface. That is, the blocking element 38 effectively defines, in this embodiment, the inner diameter of the passage cross section and the respective blade base 51 between the turbostator blades 48.

This embodiment also reduces the backflow of gas particles from the intermediate port 30. To reduce backflow, in FIGS. 8, 9 and 11, the blocking elements 38 are arranged specifically "in the path" of the particles, respectively, but here, especially even if they extend directly above the intermediate port. , The passage cross-section with low compression is shielded, or only the passage cross-section with high compression is left. The high compression itself causes the low probability that the particles will pass through the passage cross section in the direction opposite to the pump direction. The less compressed region, i.e. the inner region in the radial direction, has a relatively high probability of passage of particles, but is shielded by the blocking element 38.

Typically, the blade bases of individual turbo rotor discs and turbostator discs in the pump stage and / or the blade bases of a pair of rotor discs and stator discs associated with each other have similar diameters. In particular, the blade base diameters are, i.e., substantially the same or similar. Basically, the cross section of the passage in the pump stage is often similar. This is especially useful because the discs have about the same suction capacity. For applications that simply or primarily require high compression and / or low suction capacity, it is preferable to use only the radial outer region 49 of the stator disc. This is, by way of example, the embodiment of FIG. Basically, for this purpose it is possible to simply cover an existing stator disk, for example as illustrated in FIG. Optionally, a stator disk can be provided in which the stator blade extends only over the desired radial region. In general, the particularly effective blade base diameter of the stator disk upstream of the intermediate port 30 is preferably significant and can differ from other particularly upstream stator disk and / or rotor disk blade base diameters of this stator disk.

In FIG. 14, the Holbeck pump stage 50 is shown simplified as the Holbeck stator 52 is conceptually unfolded and shown as a flat surface. The Holbeck stator 52 has a plurality of Holbeck grooves 54, which are laterally restricted by the web 56 and separated from each other. The Holbeck rotor, not particularly the Holbeck sleeve, which is not shown here, rotates relative to the Holbeck stator 52 in the direction of rotation 58 indicated by the arrow. That is, the Holbeck rotor moves over the stator 52 from right to left in this idealized view. As a result, a pumping action is generated along the pumping direction 28.

An intermediate port 30 is provided in the Holbeck pump stage 50, and the intermediate port is formed in the Holbeck stator 52 as a notched, particularly milled, elongated hole. The intermediate port 30 is located downstream of the first portion in the pump direction 28 of the Holbeck pump stage 50 and upstream of the second portion in the pump direction 28 of the pump stage 50.

Although the Holbeck pump stage 50 causes the transfer of gas along the pump direction 28, to the first portion of the Holbeck pump stage 50 starting from the intermediate port 30, and thus the pump direction 28. It is basically possible for gas particles to move in the opposite direction. That is, the pump stage 50 of FIG. 14 has a risk of backflow 32 to be avoided, similar to that of FIG.

For this purpose, the Holbeck pump stage 50 of FIG. 15 comprises a breaking element 38. Other than that, similarly illustrated elements with the same reference numerals are appropriately configured. The pump direction 28 and the rotation direction 58 extend according to the arrows in FIG.

The blocking element 38 is formed here as a side wall, which blocks the plurality of Holbeck grooves 54, i.e., the Holbeck groove to which the intermediate port 30 is attached at its boundary. Therefore, the movement of particles to the portion of the Holbeck groove 54 upstream of the intermediate port 30 in the direction opposite to the pump direction 28 starting from the intermediate port 30 is effectively restricted.

Basically, the blocking element 38 can be formed, for example, as a horizontal web and / or the Holbeck groove 54 directly adjacent to the intermediate port 30 can be blocked from the intermediate port 30.

The blocking element 38 significantly reduces the probability of particles flowing back directly from the intermediate port 30 in the direction opposite to the pump direction 28. Particularly and generally, a turbomolecular pump stage can be provided upstream of the Holbeck pump stage 50. Therefore, the blocking element 38 in the Holbeck pump stage 50 reduces the risk of backflow to the turbomolecular pump stage. One of the effects is, for example, an increase in the pressure ratio between the intermediate port and the next port in the direction opposite to the pump direction 28. This may be, for example, an intermediate port in the turbo molecular pump stage or after the turbo molecular pump stage, or may be essentially the main inlet.

The passage cross section of the pump stage 50 is composed of the sum of the cross sections of the Holbeck groove 54 for a given axial region. The Holbeck grooves 54 or some of their cross-sections are blocked by a blocking element 38. In contrast, the remaining Holbeck grooves remain open. In this regard, it is noted that FIGS. 14-16 show the unfolded Holbeck stator 52, particularly only partially, and preferably are provided with another Holbeck groove 54 and a web 56. I want to. These figures are rather concentrated in the region of the intermediate port 30, which region does not need to extend specifically over the entire Holbeck stator 52.

The blocking element 38 specifically blocks the passage cross section in the angular region with respect to the rotor axis associated with the intermediate port 30.

The intermediate port 30 is, in this embodiment, oriented at least one of its boundaries and its longitudinal extent perpendicular to the rotor axis. Other orientations, such as orientation perpendicular to the web 56, are also possible.

Within the region 60 downstream of the intermediate port 30 in the pumping direction 28, the plurality of webs 56 have a gap for the intermediate port 30, i.e., rather than reaching the intermediate port 30, a region 60 characteristic here. It ends with a certain interval for the intermediate port 30 that matches the width of. The voids or free regions 60 allow for facilitated inflow of gas from the intermediate port 30 to the downstream portion of the Holbeck groove 54 due to the increased conductance. This also improves the pumping action as well as the risk of backflow and is advantageously complemented by the action of the blocking element 38.

Within region 60, especially the Holbeck web, is properly removed just below the intermediate port. Thereby, the suction capacity to be achieved there is increased by increasing the inflow area to the downstream portion of the intermediate port of the Holbeck pump stage 50.

In addition, the plurality of webs 56 are provided with a gap 62 for the blocking element 38 in an area upstream of the blocking element 38. That is, the web 56 does not reach the blocking element 38 in the pump direction 28, or ends at a certain interval with respect to the blocking element. The gap portion 62 constitutes a connection portion between the Holbeck groove 54 blocked by the blocking element 38 and the next Holbeck groove 54 in the rotation direction 58 of the Holbeck rotor 52.

The blocking element 38 here extends over a plurality of Holbeck grooves 54 so that all Holbeck grooves 54 blocked by the blocking element 38 are connected to an unobstructed or free Holbeck groove 54. , A large number of voids 62 are provided. That is, the Holbeck groove 54 blocked by the blocking element 38 does not form a dead end, and the particles transferred by the Holbeck groove flow out to the continuous Holbeck groove 54, where they can be further pumped. In this way, in particular, the loss of suction capacity that may arise from the blocking element 38 can be compensated, at least in part.

In particular, in combination, the blocking element 38, the voids in the region 60 and the voids 62 simultaneously increase the suction capacity at the intermediate port 30 and are opposite the direction from the intermediate port 30 to the high vacuum side, i.e. the pump direction 28. It causes a particularly significant reduction in directional backflow.

FIG. 16 shows another embodiment of the Holbeck pump stage 50 with a plurality of Holbeck grooves 54 laterally restricted or separated by a web 56. The pump direction 29 and the rotation direction 58 of the Holbeck rotor (not shown here) are indicated by arrows and extend according to FIGS. 14 and 15.

The embodiment of FIG. 16 has two intermediate ports 30, which are similarly arranged and formed, so that what is described below is limited to the left side of the intermediate port 30 illustrated herein. However, it can be seen that basically one or more intermediate ports 30 like this can be provided and the number selected here is exemplary.

The intermediate port 30 is attached to only one Holbeck groove 54 in this embodiment. That is, the boundary does not extend over the plurality of Holbeck grooves 54. In this case, the intermediate port 30 is advantageously arranged with its boundary substantially parallel to the Holbeck groove 54.

A cutoff element 38 is provided upstream of the intermediate port 30 in the pump direction 28, which limits backflow along the Holbeck groove 54. Since the Holbeck groove 54 is connected to the next Holbeck groove 54 in the rotation direction 58 via the gap portion 62 of the web 56 that restricts the groove 54 from the side, the gas particles are blocked by the blocking element 38 and are intermediate. Instead of reaching the dead end from the Holbeck groove 54 to which the port 30 is attached, the particles are discharged by the next Holbeck groove 54.

The movement of gas particles is shown here schematically by dotted arrows. From the intermediate port 30, particles can, on the other hand, flow into a portion downstream of the intermediate port 30 of the Holbeck groove 54-where the intermediate port 30 is attached. The web 56 arranged between the Holbeck groove 54 and the next Holbeck groove 54 in the direction of rotation 58 includes a notch 64 that connects the Holbeck groove 54 to each other. That is, on the other hand, each particle can reach the next Holbeck groove 54 in the rotation direction 58 from the intermediate port 30. Therefore, the intermediate port 30 is countered by low conductance, facilitating the inflow of gas into the Holbeck pump stage 50.

In principle, the goal is, in particular, to reduce the probability of inflows and immediate re-spills through the same intermediate port 30. The more obliquely the intermediate port 30 is arranged, the lower the probability that the particles will leave the intermediate port 30 again immediately after colliding with the rotating Holbeck sleeve. This is because the width of the passage is smaller than that of the intermediate port according to FIG. 14 or 15. Besides the tilt of the intermediate port, it is advantageous that the web has been removed in the desired transport direction. In the left half of FIG. 16, arrows indicate that a large number of particles take a path in the direction of the pump. The particles either move directly into the associated Holbeck groove 54 or move into the adjacent Holbeck groove 54 via a priority direction after collision with the Holbeck sleeve. At the upper right of each intermediate port 30, the blocking element 38 prevents the particles from being transported towards the high vacuum side. The void 62 is advantageously used because the particles can reach into the adjacent Holbeck groove 54 from the Holbeck groove 54 blocked by the blocking element 38 and thus transfer in the pump direction can be maintained.

In general, it is possible to form the blocking element 38 in a modifiable manner in order to achieve particularly selectively different performance with respect to backflow.

In particular, the Holbeck stator 52 of FIGS. 15 and 16 has a very complex shape and can therefore be manufactured by 3D printing or generally by a production process, preferably in a particularly simple manner. Basically, the remaining stators and / or blocking elements introduced here can also be manufactured by a production process such as 3D printing.

111 Turbo Molecular Pump 113 Inlet Flange 115 Pump Inlet 117 Pump Outlet 119 Housing 121 Bottom 123 Electronic Equipment Housing 125 Electric Motor 127 Accessory Port 129 Data Interface 131 Power Supply Port 133 Filling Water Inlet 135 Sealed Gas Port 137 Motor Space 139 Coolant Port 141 Lower 143 Bolt 145 Bearing Cover 147 Fixing Hole 148 Coolant Line 149 Rotor 151 Rotating Shaft 153 Rotor Shaft 155 Rotor Disc 157 Stator Disc 159 Spacer Ring 161 Rotor Hub 163 Holbeck Rotor Sleeve 165 Holbeck Rotor Sleeve 167 Holbeck Stator Sleeve 169 Hol Beck stator sleeve 171 Holbeck gap 173 Holbeck gap 175 Holbeck gap 179 Connection passage 181 Rolling bearing 183 Permanent magnet bearing 185 Spray nut 187 Disc 189 Insert 191 Rotor side bearing half body 193 Stator side bearing half body 195 Ring magnet 197 Ring magnet 199 Bearing gap 201 Carrier part 203 Carrier part 205 Radial brace 207 Cover element 209 Support ring 211 Fixed ring 213 Countersunk spring 215 Emergency or safety bearing 217 Motor stator 219 Intermediate space 221 Wall 223 Labyrinth seal 20 Vacuum pump 22 Rotor shaft 24 Turbo rotor disk 26 Turbo stator disk 28 Pump direction 30 Intermediate port 32 Backflow 34 Intermediate port 36 Notch / boundary 38 Blocking element 40 Particle movement 41 Turbo molecular pump stage 42 First pump stage 44 Second pump stage 46 Intermediate Stage area 48 Turbo stator blade 49 Area 50 Holbeck pump stage 51 Blade base 52 Holbeck stator 54 Holbeck groove 56 Web 58 Rotation direction 60 Region / Void part 62 Void part

Claims (7)

It has at least one molecular pump stage (41, 42, 50) and one intermediate port (30), through which the gas can be transferred from the inlet to the outlet of the molecular vacuum pump (20) and the pump stage. (41, 42, 50) has one pump direction (28) and one passage cross section laterally to this pump direction (28), with an intermediate port in the pump stage (41, 50) or A static cutoff element (38) is placed downstream of the pump stage (42) and in front of the intermediate port (30) in the pump direction (28), which causes the passage cross section to be localized locally. In the reduced molecular vacuum pump (20)
The pump stage is a Holbeck pump stage (50), the blocking element (38) is formed as a side wall of at least one Holbeck groove (54), and the Holbeck groove (54) is laterally restricted. And / or at least one web (56) separating adjacent Holbeck grooves (54) from each other in the region upstream of the blocking element (38) in the pumping direction (28), a gap (38) with respect to the blocking element (38). 62) The molecular vacuum pump (20). The cutoff element (38) is located on the side of the intermediate port (30) of the rotor shaft (22) of the pump stage, and / or the shape of the cutoff element (38) can be changed. The molecular vacuum pump (20) according to claim 1. The molecular vacuum pump (20) according to claim 1 or 2 , wherein the blocking element (38) extends radially only over a portion of the passage cross section of the pump stage. At least one web (56) that laterally limits the Holbeck groove (54) and / or separates adjacent Holbeck grooves (54) from each other is located in the area downstream of the intermediate port (30) in the pump direction (28) (60). The molecular vacuum pump (20) according to any one of claims 1 to 3 , wherein the intermediate port (30) is provided with a gap portion. The intermediate port (30) has its boundaries attached to only one Holbeck groove (54) and / or the intermediate ports (30) have at least one boundary and / or one longitudinal extension. The molecular vacuum pump (20) according to any one of claims 1 to 4 , wherein the molecular vacuum pump (20) is oriented parallel to at least substantially one Holbeck groove (54). The intermediate port (30) is provided with its boundary in at least one first Holbeck groove (54) and in the next at least one second Holbeck groove (54) in the direction of rotation of the Holbeck rotor. The claim is characterized in that the web (56) between the first and second Holbeck grooves is provided with a notch connecting the intermediate port (30) to the second Holbeck groove (54). The molecular vacuum pump (20) according to any one of 1 to 5 . The stator element (26, 52) disposed at the cutoff element (38) and / or the intermediate port (30) and with the cutoff element (38) is characterized by being manufactured by a production process, i.e. , 3D printing. The molecular vacuum pump (20) according to any one of claims 1 to 6 .

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