EP3561306B1 - Vacuum pump - Google Patents

Description

The present invention relates to a vacuum pump, in particular a turbo-molecular pump, according to the preamble of claim 1. Such a pump is disclosed in US Pat DE 10 2005 052 792 A1 disclosed. Further prior art are the JP 2005-291040A , the EP 3 034 881 A1 and the US 2013/0129482 A1 .

Vacuum pumps are used under different operating conditions. One of these conditions can include, for example, strong, alternating magnetic fields that have a negative effect on an electronic control of the vacuum pump and can also pass through the pump into the environment. This can be the case, for example, when using vacuum pumps in conjunction with mass spectrometers or other recipients. This can be problematic in particular in environments in which there are comparatively strict regulations or guidelines in this regard and relatively low limit values must be adhered to.

It is an object of the invention, in the case of a vacuum pump of the type mentioned at the outset, to ensure its functionality and that the surroundings are not impaired, even under the influence of particularly strong electric and / or magnetic fields.

This object is achieved by a vacuum pump according to claim 1. This comprises at least one housing section and at least one shielding means, the shielding means on the housing section for electromagnetic shielding of an interior of the pump from an exterior of the pump is formed, wherein the shielding means is designed as a grid on an inlet flange and / or discharge flange and wherein the shielding means comprises copper and / or beryllium.

The fact that at least one shielding means is provided, the shielding means being formed on a housing section for electromagnetic shielding of an interior of the pump from an exterior of the pump, ensures that electrical and / or magnetic fields that occur outside the vacuum pump prevent the operation of the Do not interfere with the vacuum pump or affect the environment. In addition, electrical and / or magnetic fields that may possibly occur inside the vacuum pump are effectively shielded so that electronic functional elements outside the pump are not disturbed in their function by these fields.

According to claim 1, the shielding means comprises copper and / or beryllium, which have particularly good shielding properties, in particular because of their electrical conductivity.

In a further development, the housing section is a first housing section which comprises at least one interface for connecting the first housing section to a second housing section of the vacuum pump or to a connection component for the vacuum pump. The shielding means is provided at the interface. The connection component can, for example, form or comprise a recipient of the vacuum pump.

The shielding means can, for example, be formed exclusively on the first housing section or can be formed in one piece with the first housing section.

The shielding means can comprise an EMC seal. This allows large electrical contact surfaces and thus particularly good shielding to be achieved. The shielding means can alternatively or additionally be designed as a sheet metal element, in particular comprising copper. A material overlap can also be provided at the interface described above. Advantageously, no clearance fit, in particular a transition or interference fit, can be provided at the interface, i.e. such a clearance or transition or interference fit can be specifically prevented or reduced by the invention. This further improves the shielding effect.

As an alternative or in addition, the shielding means can have an, in particular metallic, coating for shielding. The shielding means can comprise, for example, a shielding tape, in particular adhesive tape, and / or a shielding film, for example a bag, which optionally essentially completely encloses the pump.

The interface can have a surface structure. In particular, a surface of the first housing section can have a surface structure which is designed to engage with a surface of the second housing section or the connection component.

In a further embodiment, the shielding means comprises a conductive paste and / or a conductive elastomer, which advantageously has metallic particles. In particular, an O-ring or another elongated sealing element, for example in the form of a sealing cord made of basically any material with metallic particles, can be provided as a shielding means. Generally the shielding means may comprise a plastic and / or in particular be easily deformable.

According to claim 1, the shielding means is designed as a grid on an inlet flange. As a result, the interior of the pump can be effectively shielded from an interior of a connected recipient, in which, for example, strong magnetic fields prevail. Alternatively or additionally, according to claim 1, the shielding means can be designed as a grid on an ejection flange. Through the grid, the inside of the pump can also be effectively shielded from external electromagnetic influences at the openings required for vacuum technology, such as inlet and discharge openings, which can be comparatively large.

According to claim 2 it is provided that the shielding means has at least one contact element for making electrical contact between the shielding means and the housing section. The contact element is designed to be resilient. In particular, the shielding means can be held on the housing section by the contact element or by a plurality of contact elements. Thus, in particular, no additional fastening means are necessary for fixing the shielding means. The shielding means can advantageously be held by a restoring force exerted by at least one contact element, in particular on an inner surface of an inlet or outlet flange.

In a further embodiment, at least two differently designed contact elements are provided. For example, one of the contact elements can be designed to hold the shielding means and another only to make electrical contact between the shielding means and the housing section. In principle, a contact element can have either a holding function and a contacting function or just a contacting function, for example.

It can also advantageously be provided that the various contact elements extend in different directions, in particular enclose an angle of more than 45 ° or at least run essentially perpendicular to one another.

Alternatively or additionally, at least one contact element can extend at an angle of more than 45 ° or at least essentially perpendicular to a main surface of the shielding means.

According to one embodiment, the shielding means has a plurality of sides and at least two contact elements, in particular a plurality of contact elements, are provided on each side. This makes it possible to ensure that several, in particular many, contact points formed by the contact elements are present between the shielding means and the housing section during operation, as a result of which the shielding is further improved. For example, more than four, in particular more than eight, contact elements can be provided on the shielding means, which contact elements in particular also hold the shielding means on the housing section.

As an alternative or in addition, the shielding means can be arranged in a recess of the housing section and / or be essentially flat. The shielding means can thus be attached and / or fastened to the housing section in a space-saving manner.

In a further development, the shielding means has a shielding area and a contact area, the contact area having a plurality of contact elements that are spaced apart from one another and protrude from the shielding area for contacting the shielding means with the housing section.

The shielding area can thereby be optimized with regard to its shielding function.

The shielding element can be manufactured and installed particularly easily if the shielding means is designed in one piece. For example, the shielding means can be produced by etching, punching and / or laser cutting. In particular, the shielding means can also be a bent part. A particularly simple and inexpensive production of the shielding means can thus be realized.

Further embodiments of the invention can be found in the claims, the description and the figures.

Fig. 1

eine perspektivische Ansicht einer Turbomolekularpumpe des Standes der Technik,

Fig. 2

eine Ansicht der Unterseite der Turbomolekularpumpe von Fig. 1,

Fig. 3

einen Querschnitt der Turbomolekularpumpe längs der in Fig. 2 gezeigten Schnittlinie A-A,

Fig. 4

eine Querschnittsansicht der Turbomolekularpumpe längs der in Fig. 2 gezeigten Schnittlinie B-B,

Fig. 5

eine Querschnittsansicht der Turbomolekularpumpe längs der in Fig. 2 gezeigten Schnittlinie C-C,

Fig. 6

eine perspektivische Detailansicht einer erfindungsgemäßen Vakuumpumpe

Fig. 7

eine vergrößerte Ansicht eines Ausschnitts der Fig. 6.

The invention is described below by way of example using advantageous embodiments with reference to the accompanying figures. Show it:

Fig. 1

a perspective view of a turbomolecular pump of the prior art,

Fig. 2

a view of the underside of the turbo molecular pump of FIG Fig. 1 ,

Fig. 3

a cross section of the turbo molecular pump along the in Fig. 2 shown section line AA,

Fig. 4

a cross-sectional view of the turbo molecular pump along the line in FIG Fig. 2 shown section line BB,

Fig. 5

a cross-sectional view of the turbo molecular pump along the line in FIG Fig. 2 shown section line CC,

Fig. 6

a perspective detailed view of a vacuum pump according to the invention

Fig. 7

an enlarged view of a portion of the Fig. 6 .

In the Fig. 1 The turbo molecular pump 111 shown comprises a pump inlet 115 which is surrounded by an inlet flange 113 and to which a recipient (not shown) can be connected in a manner known per se. The gas from the recipient can be sucked out of the recipient via the pump inlet 115 and conveyed through the pump to a pump outlet 117 to which a backing pump, such as a rotary vane pump, can be connected.

In the orientation of the vacuum pump, the inlet flange 113 forms according to FIG Fig. 1 the upper end of the housing 119 of the vacuum pump 111. The housing 119 comprises a lower part 121 on which an electronics housing 123 is arranged laterally. Electrical and / or electronic components of the vacuum pump 111 are accommodated in the electronics housing 123, for example for operating an electric motor 125 arranged in the vacuum pump. A plurality of connections 127 for accessories are provided on the electronics housing 123. In addition, a data interface 129, for example in accordance with the RS485 standard, and a power supply connection 131 are arranged on the electronics housing 123.

A flood inlet 133, in particular in the form of a flood valve, is provided on the housing 119 of the turbo molecular pump 111, via which the vacuum pump 111 can be flooded. In the area of the lower part 121 there is also a sealing gas connection 135, which is also referred to as a purging gas connection, via which purging gas is used to protect the electric motor 125 (see e.g. Fig. 3 ) can be brought into the engine compartment 137, in which the electric motor 125 in the vacuum pump 111 is accommodated, before the gas conveyed by the pump. in the Lower part 121 also has two coolant connections 139, one of the coolant connections being provided as an inlet and the other coolant connection being provided as an outlet for coolant, which can be fed into the vacuum pump for cooling purposes.

The lower side 141 of the vacuum pump can serve as a standing surface, so that the vacuum pump 111 can be operated standing on the lower side 141. The vacuum pump 111 can, however, also be attached to a recipient via the inlet flange 113 and can thus be operated in a suspended manner, as it were. In addition, the vacuum pump 111 can be designed in such a way that it can also be put into operation when it is oriented in a different way than in FIG Fig. 1 is shown. Embodiments of the vacuum pump can also be implemented in which the underside 141 cannot be arranged facing downwards, but facing to the side or facing upwards.

At the bottom 141, which in Fig. 2 is shown, various screws 143 are also arranged by means of which components of the vacuum pump not specified here are attached to one another. For example, a bearing cap 145 is attached to the underside 141.

Fastening bores 147 are also arranged on the underside 141, via which the pump 111 can be fastened to a support surface, for example.

In the Figures 2 to 5 a coolant line 148 is shown, in which the coolant introduced and discharged via the coolant connections 139 can circulate.

Like the sectional views of the Figures 3 to 5 show, the vacuum pump comprises several process gas pump stages for conveying the process gas present at the pump inlet 115 to the pump outlet 117.

A rotor 149 is arranged in the housing 119 and has a rotor shaft 153 rotatable about an axis of rotation 151.

The turbo-molecular pump 111 comprises several turbo-molecular pump stages connected in series with one another with several radial rotor disks 155 fastened to the rotor shaft 153 and stator disks 157 arranged between the rotor disks 155 and fixed in the housing 119. A rotor disk 155 and an adjacent stator disk 157 each form a turbomolecular one Pumping stage. The stator disks 157 are held at a desired axial distance from one another by spacer rings 159.

The vacuum pump also comprises Holweck pump stages which are arranged one inside the other in the radial direction and are connected in series with one another for effective pumping. The rotor of the Holweck pump stages comprises a rotor hub 161 arranged on the rotor shaft 153 and two cylinder-jacket-shaped Holweck rotor sleeves 163, 165 which are attached to the rotor hub 161 and carried by the latter, which are oriented coaxially to the axis of rotation 151 and nested in one another in the radial direction. Furthermore, two cylinder jacket-shaped Holweck stator sleeves 167, 169 are provided, which are also oriented coaxially to the axis of rotation 151 and, viewed in the radial direction, are nested one inside the other.

The active pumping surfaces of the Holweck pump stages are formed by the jacket surfaces, that is to say by the radial inner and / or outer surfaces, of the Holweck rotor sleeves 163, 165 and the Holweck stator sleeves 167, 169. The radial inner surface of the outer Holweck stator sleeve 167 lies on the radial outer surface of the outer Holweck rotor sleeve 163 with the formation of a radial Holweck gap 171 opposite and with this forms the first Holweck pump stage following the turbo molecular pumps. The radial inner surface of the outer Holweck rotor sleeve 163 faces the radial outer surface of the inner Holweck stator sleeve 169 with the formation of a radial Holweck gap 173 and forms with this a second Holweck pumping stage. The radial inner surface of the inner Holweck stator sleeve 169 lies opposite the radial outer surface of the inner Holweck rotor sleeve 165 with the formation of a radial Holweck gap 175 and with this forms the third Holweck pumping stage.

At the lower end of the Holweck rotor sleeve 163, a radially running channel can be provided, via which the radially outer Holweck gap 171 is connected to the central Holweck gap 173. In addition, a radially running channel can be provided at the upper end of the inner Holweck stator sleeve 169, via which the middle Holweck gap 173 is connected to the radially inner Holweck gap 175. As a result, the nested Holweck pump stages are connected in series with one another. A connecting channel 179 to the outlet 117 can also be provided at the lower end of the radially inner Holweck rotor sleeve 165.

The aforementioned pump-active surfaces of the Holweck stator sleeves 163, 165 each have a plurality of Holweck grooves running spirally around the axis of rotation 151 in the axial direction, while the opposite lateral surfaces of the Holweck rotor sleeves 163, 165 are smooth and the gas for operating the Drive vacuum pump 111 in the Holweck grooves.

For the rotatable mounting of the rotor shaft 153, a roller bearing 181 is provided in the area of the pump outlet 117 and a permanent magnetic bearing 183 in the area of the pump inlet 115.

In the area of the roller bearing 181, a conical injection molded nut 185 is provided on the rotor shaft 153 with an outer diameter that increases towards the roller bearing 181. The injection-molded nut 185 is in sliding contact with at least one stripper of an operating medium reservoir. The operating medium reservoir comprises several absorbent disks 187 stacked on top of one another, which are impregnated with an operating medium for the roller bearing 181, e.g. with a lubricant.

During operation of the vacuum pump 111, the operating medium is transferred by capillary action from the operating medium reservoir via the scraper to the rotating injection nut 185 and, as a result of the centrifugal force, is conveyed along the injection nut 185 in the direction of the increasing outer diameter of the injection nut 185 to the roller bearing 181, where it eg fulfills a lubricating function. The roller bearing 181 and the operating medium store are enclosed in the vacuum pump by a trough-shaped insert 189 and the bearing cover 145.

The permanent magnetic bearing 183 comprises a rotor-side bearing half 191 and a stator-side bearing half 193, each of which comprises a ring stack of several permanent magnetic rings 195, 197 stacked on top of one another in the axial direction. The ring magnets 195, 197 are opposite one another with the formation of a radial bearing gap 199, the rotor-side ring magnets 195 being arranged radially on the outside and the stator-side ring magnets 197 being arranged radially on the inside. The magnetic field present in the bearing gap 199 causes magnetic repulsive forces between the ring magnets 195, 197, which cause the rotor shaft 153 to be supported radially. The rotor-side ring magnets 195 are carried by a carrier section 201 of the rotor shaft 153 which surrounds the ring magnets 195 radially on the outside. The stator-side ring magnets 197 are carried by a stator-side support section 203 which extends through the ring magnets 197 and is suspended from radial struts 205 of the housing 119. The ring magnets 195 on the rotor side are parallel to the axis of rotation 151 by means of a cover element coupled to the carrier section 203 207 set. The stator-side ring magnets 197 are fixed parallel to the axis of rotation 151 in one direction by a fastening ring 209 connected to the carrier section 203 and a fastening ring 211 connected to the carrier section 203. A plate spring 213 can also be provided between the fastening ring 211 and the ring magnet 197.

An emergency or retainer bearing 215 is provided inside the magnetic bearing, which runs empty during normal operation of the vacuum pump 111 without contact and only comes into engagement with an excessive radial deflection of the rotor 149 relative to the stator to create a radial stop for the rotor 149 to form, since a collision of the rotor-side structures with the stator-side structures is prevented. The backup bearing 215 is designed as an unlubricated roller bearing and forms a radial gap with the rotor 149 and / or the stator, which has the effect that the backup bearing 215 is disengaged during normal pumping operation. The radial deflection at which the backup bearing 215 engages is dimensioned large enough that the backup bearing 215 does not come into engagement during normal operation of the vacuum pump, and at the same time small enough so that a collision of the rotor-side structures with the stator-side structures under all circumstances is prevented.

The vacuum pump 111 comprises the electric motor 125 for rotatingly driving the rotor 149. The armature of the electric motor 125 is formed by the rotor 149, the rotor shaft 153 of which extends through the motor stator 217. A permanent magnet arrangement can be arranged radially on the outside or embedded on the section of the rotor shaft 153 extending through the motor stator 217. Between the motor stator 217 and the section of the rotor 149 that extends through the motor stator 217, an intermediate space 219 is arranged, which comprises a radial motor gap over which the motor stator 217 and the permanent magnet arrangement for transmitting the drive torque can influence each other magnetically.

The motor stator 217 is fixed in the housing within the motor compartment 137 provided for the electric motor 125. A sealing gas, which is also referred to as a flushing gas and which can be air or nitrogen, for example, can enter the engine compartment 137 via the sealing gas connection 135. The electric motor 125 can be protected from process gas, e.g. from corrosive components of the process gas, via the sealing gas. The engine compartment 137 can also be evacuated via the pump outlet 117, i.e. in the engine compartment 137 there is at least approximately the vacuum pressure produced by the backing pump connected to the pump outlet 117.

A so-called and known labyrinth seal 223 can also be provided between the rotor hub 161 and a wall 221 delimiting the engine compartment 137, in particular in order to achieve better sealing of the motor compartment 217 with respect to the radially outside Holweck pump stages.

All the features of the vacuum pump described above can also be provided in the vacuum pump according to the invention described below, i.e. a vacuum pump according to the invention can in principle have any combination of features of the vacuum pump described above.

In Fig. 6 a vacuum pump 10 according to the invention is shown with a housing section which is designed as a so-called split-flow turbo-molecular pump. The vacuum pump 10 has an inlet flange 12 with two inlets 16. The two inlets 16 can be connected to different spaces of a recipient, for example in the form of a mass spectrometer, via the flange 12. The inlet flange 12 forms an interface for connecting the housing section the vacuum pump 10 with this recipient or alternatively, for example, with two recipients.

In each of the two inlets 16, a shielding means designed as a grid 20 is arranged. A respective grille 20 is flat and shields an interior of the pump 10 from an interior of the recipient or recipients.

In Fig. 7 is the right grid 20 of the Fig. 6 shown enlarged. The grid 20 comprises a grid structure 26 which is designed as a honeycomb structure. However, a different lattice structure, for example a rectangular structure, can also be provided. The lattice structure 26 is surrounded by an edge 28 from which a multiplicity of contact elements 22 and 24 extend. The contact elements 22 and 24 each form an electrical contact between the grille 20 and an inner wall 14 of the inlet flange 12.

The grid 20 has a shielding area and a contact area, the contact elements 22 and 24 being provided in the contact area which is formed by the edge area of the grid 20. The contact elements 22 and 24 are spaced from one another and protrude from the shielding area in order to make contact between the grid 20 and the housing section. The grid 20 is formed in one piece. Different types of contact elements are provided, namely a set of contact elements 22 and a set of contact elements 24.

A respective contact element 22, which is comparatively large and has a tab-like or tongue-like design, not only ensures contact, but also serves to hold the grid 20 in the inlet 16. The contact element 22 is designed as a tab or tongue which extends from the edge 28 essentially perpendicular to a main surface of the grid 20. The contact elements 22 are arranged in rows, the contact elements 22 extend parallel to one another in a row and have a spacing that is constant over the row.

The grid 20 is formed from a metallic material and a respective contact element 22 is bent into the in Fig. 7 Alignment shown brought. The contact element 22 is designed in such a way that it exerts a restoring force in the direction of the inner wall 14 and thus makes electrical contact with the grid on the one hand with this inner wall 14 and on the other hand holds it in a frictional manner on this inner wall 14. All of the contact elements 22 together produce a sufficiently high holding force to hold the grid 20 in the inlet 16. Since the contact elements 22 can be deflected independently of one another relative to the main surface of the grid 20, the grid 20 can adhere to any tolerances that may exist with regard to the dimensions of the opening forming the inlet 16 or with regard to the course of the inner wall 14 delimiting this opening with which the contact elements 22 cooperate, adapt.

A respective contact element 24, which is comparatively small, is also designed to be resilient, namely as a tab or tongue which extends from the edge 28 essentially parallel to the main surface of the grid 20 and essentially perpendicular to the inner wall 14. These contact elements 24 are only provided in the respective corner regions of the inlet flange 16 or of the grille 20, the inner wall 14 having a radius in a respective corner region. The grid 20 is recessed in the respective corner areas, the contact elements 24 remaining. The contact elements 24 of a corner region thus extend essentially in one plane, but are not parallel to one another, but rather extend in respective directions which preferably intersect at a center point of the radius.

The contact elements 24 are each dimensioned to be so long that when the grid 20 is inserted they are in Fig. 7 from above - through the inner wall 14 relative to the Main surface of the grid 20 are bent upwards and ensure contact is made by the restoring force resulting therefrom on the inner wall 14.

This pump according to the invention can be provided with further shielding means, as described, for example, in the introductory part.

List of reference symbols

10

Vacuum pump

12th

Inlet flange

14th

Inner wall

16

inlet

20th

Grid

22nd

Contact element

24

Contact element

26th

Lattice structure

28

edge

111

Turbo molecular pump

113

Inlet flange

115

Pump inlet

117

Pump outlet

119

casing

121

Lower part

123

Electronics housing

125

Electric motor

127

Accessory connection

129

Data interface

131

Power supply connection

133

Flood inlet

135

Sealing gas connection

137

Engine compartment

139

Coolant connection

141

bottom

143

screw

145

Bearing cap

147

Mounting hole

148

Coolant line

149

rotor

151

Axis of rotation

153

Rotor shaft

155

Rotor disk

157

Stator disc

159

Spacer ring

161

Rotor hub

163

Holweck rotor sleeve

165

Holweck rotor sleeve

167

Holweck stator sleeve

169

Holweck stator sleeve

171

Holweck gap

173

Holweck gap

175

Holweck gap

179

Connection channel

181

roller bearing

183

Permanent magnet bearings

185

Injection nut

187

disc

189

commitment

191

bearing half on the rotor side

193

stator-side bearing half

195

Ring magnet

197

Ring magnet

199

Bearing gap

201

Beam section

203

Beam section

205

radial strut

207

Cover element

209

Support ring

211

Fastening ring

213

Disc spring

215

Emergency or fishing camp

217

Motor stator

219

Space

221

Wall

223

Labyrinth seal

Claims (11)

1. A vacuum pump (10), in particular a turbomolecular pump, comprising at least one housing section; and
   at least one shielding means (20),
   wherein the shielding means (20) is formed at the housing section to electromagnetically shield an interior of the pump (10) with respect to an exterior of the pump (10), and
   wherein the shielding means (20) comprises copper and/or beryllium, characterized in that
   the shielding means is formed as a lattice (20) at an inlet flange (12) and/or an expulsion flange.
2. A vacuum pump (10) in accordance with claim 1,
   characterized in that
   the shielding means (20) has at least one resilient contact element (22, 24) for the electrical contacting of the shielding means (20) with the housing section.
3. A vacuum pump (10) in accordance with one of the preceding claims,
   characterized in that
   the housing section is a first housing section and comprises at least one interface for connecting the first housing section to a second housing section of the vacuum pump or to a connection component for the vacuum pump (10), with the shielding means (20) being provided at the interface.
4. A vacuum pump (10) in accordance with claim 2,
   characterized in that
   the shielding means (20) is held at the housing section by the contact element or by a plurality of contact elements (22).
5. A vacuum pump (10) in accordance with any one of the claims 2 to 4,
   characterized in that
   at least two differently formed contact elements (22, 24) are provided.
6. A vacuum pump (10) in accordance with claim 5,
   characterized in that
   the different contact elements (22, 24) extend in different directions, in particular enclose an angle of more than 45° or extend at least substantially perpendicular to one another.
7. A vacuum pump (10) in accordance with any one of the claims 2 to 6,
   characterized in that
   at least one contact element (22) extends at an angle of more than 45° or extends at least substantially perpendicular to a main surface of the shielding means (20).
8. A vacuum pump (10) in accordance with any one of the preceding claims,
   characterized in that
   the shielding means (20) is arranged in a recess of the housing section.
9. A vacuum pump (10) in accordance with any one of the preceding claims,
   characterized in that
   the shielding means (20) is substantially of an areal design.
10. A vacuum pump (10) in accordance with any one of the preceding claims,
    characterized in that
    the shielding means (20) has a shielding region and a contact region which has a plurality of contact elements (22, 24) which are spaced apart from one another and which project from the shielding region for the contacting of the shielding means (20) with the housing section.
11. A vacuum pump (10) in accordance with any one of the preceding claims,
    characterized in that
    the shielding means (20) is formed in one part.

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