EP4390130A1 - Pump and method for forming seal - Google Patents

Abstract

The present invention relates to a pump, in particular a vacuum pump, comprising a pump-active component with a coating, wherein the coating comprises an oxide layer having pores, in particular formed by anodic oxidation in an acidic electrolyte, and a fluorine-free polymer-based and/or sol-gel-based seal, and wherein the pores of the oxide layer are at least partially covered by the seal and/or impregnated with the seal and/or filled with the seal. The present invention further relates to a method for sealing a porous oxide layer.

Description

The present invention relates to a pump, in particular a vacuum pump, which comprises, for example, at least two conveying elements that are movable relative to one another, at least one seal arranged on one of the two conveying elements. According to the invention, a seal is provided that is applied at least in some areas to at least one of the conveying elements. In addition, the invention relates to the use of components provided with a seal and at least one seal for producing pumps, in particular vacuum pumps, and also to a method for producing a seal.

Fluids such as grease or oil can generally be used to seal the delivery chamber of pumps, particularly vacuum pumps. A piston pump, for example, always has a gap between the delivery chamber and the piston. In a fluid-sealed or fluid-lubricated version, this gap is filled by a fluid, usually oil or grease, during operation of the pump, with the fluid acting as a seal between the piston and the delivery chamber. Furthermore, defects in the surface structure (cracks, holes, pores, etc.) can have a gap-forming effect. In particular, some coatings (paints, anodized layers, etc.) have defects. A disadvantage of such pumps is that the media conveyed by the pump, such as gases or vapors, can react with the fluids used as a seal, which can in particular reduce the sealing effect. Another problem, particularly with vacuum pumps, is contamination of the recipient by the fluids used.

For this reason, so-called dry solutions are preferred, especially for vacuum pumps, in which the media being pumped do not come into contact with fluids. In principle, sliding or sliding seals made of chemically resistant materials, usually plastics, are used. In a piston pump, for example, such seals are usually arranged on the piston. During operation, the seal rubs against an inner wall of a cylinder in order to seal the resulting pumping chamber as hermetically as possible. Another example of a pump that is also usually operated dry, i.e. without fluid lubricants, is a scroll or spiral pump. Scroll pumps have sickle-shaped pumping chambers that are formed by a rotor with a spiral cross-section in engagement with a similar spiral stator, with the rotor being set in an orbiting movement by an eccentric drive. To seal the pumping chambers, seals are provided on the front sides of the spiral, with the front seal of the rotor rubbing against the stator and vice versa.

The disadvantage of such sliding or grinding seals is that they are usually subject to very heavy wear due to the constant sliding friction and often have only a limited service life. In particular, after a certain period of operation, the seals in the pump chamber can become abrasive in the form of dust. As wear increases, the sealing effect of the grinding seal decreases, which reduces the achievable final pressure.

To reduce wear, sliding or protective layers can be provided, such as those used in EP 3 153 706 A1 Such seals can comprise an oxide layer formed by anodic oxidation in an acidic electrolyte, in particular containing oxalic acid, sulphuric acid or mixtures thereof. These seals/protective layers also increase the corrosion and wear resistance of the base material.

There are very narrow gaps (a few 0.01 mm) between the crescent-shaped scoop chambers. In the event of contact between the two components forming the scoop chamber or solid bodies penetrating the chamber, the hard sliding and protective layer ensures a longer service life for the base material. However, it has been found that such oxide layers, due to their porous structure, cannot achieve the required final pressures and gas tightness, or can only achieve them after a longer period of time (so-called running-in period). Tests have shown that, particularly with newly coated components, a heating process for the coated components can achieve reduced running-in periods or improved final pressures, but there is still a need for improvement in terms of the achievable final pressures and a reduction in running-in periods.

Increased corrosion resistance is not only required for piston pumps and scroll pumps, but also for turbomolecular pumps. Turbomolecular pumps are vacuum pumps that have a rotor that rotates around a rotational axis of the rotor shaft. Pump-active components can be made of a light metal, especially aluminum, that is provided with an oxide layer to increase corrosion resistance, similar to the above-mentioned sliding or protective layers, such as those used in EP 3 153 706 A1 are described.

During operation, the pump-active components come into contact with the pumped medium, which can have a corrosive effect on the pump-active components. This can then lead to electrolytic corrosion, which begins at the pores of components with a porous oxide layer.

It is therefore an object of the present invention to provide pumps with improved corrosion protection.

This object is achieved by a pump and by a method according to the independent claims.

The pump according to the invention is preferably a vacuum pump. The pump comprises a pump-active component with a coating, wherein the coating comprises a porous oxide layer and a fluorine-free polymer-based and/or sol-gel-based seal, and wherein the pores of the oxide layer are at least partially covered by the seal and/or impregnated with the seal and/or filled with the seal.

It has been found that in a pump according to the invention, the pump-active component is protected from corrosion due to the sealing. In particular, electrolytic corrosion, which typically begins at the pores, is effectively prevented with the sealing according to the invention. Due to the sealing, this corrosion protection is provided for different types of pumps, such as scroll pumps, turbomolecular pumps or piston pumps.

The seal also performs other tasks. In scroll and piston pumps, the seal also acts as a sliding layer, so that two functions are fulfilled: 1) Sliding layer/optimization of the tribological system. 2) Protective layer; protection of the base material from damage, wear and corrosion. Tests have shown that without a hard surface coating, especially on scroll pumps, the base material can be damaged within a very short time.

The oxide layer is preferably formed by anodic oxidation, in particular in an acidic electrolyte. The electrolyte preferably contains oxalic acid and/or sulfuric acid, with sulfuric acid being even more preferred. The oxide layer is preferably an anodized aluminum formed by electrolytic oxidation of aluminum. This oxide layer can have the above-mentioned multifunctional properties with regard to sliding and protective effects, provided that the sealant as described herein is applied thereto.

It has been found that a pump according to the invention with a sliding layer comprising an oxide layer and a seal, e.g. in the form of a fluorine-free polymer impregnation and/or sol-gel impregnation, enables lower final pressures than sliding layers, such as those used in EP 3 153 706 A1 or in EP 3 940 234 A2 The hard oxide layers applied for wear protection have pores, defects and thermally induced cracks. The pores are mainly arranged perpendicular to the layer, although there are also some branches within the layer that are arranged horizontally to the layer and connect the vertical pores to one another. In addition to the pores, such hard oxide layers have other defects, e.g. in the form of inclusions and cracks. Defects and pores represent microscopic channels through which gases can flow. Furthermore, substances such as water can outgas from these areas. This reduces the gas tightness, which has an undesirable effect on the achievable final pressures. This means that, particularly with scroll pumps, the required final pressures and gas tightness cannot be achieved or can only be achieved after a long period of operation. During the so-called running-in process, pores and defects are largely closed at relevant points by the wear of the seal. Furthermore, the enclosed media, e.g. coating residues, outgas. It has been found that the sealing allows the required final pressures to be reached even faster, while at the same time ensuring a high Wear protection is maintained. This can presumably be explained by the fact that in the pump according to the invention, pores contained in the oxide layer are closed by the seal and gas flow within the sealed layer, e.g. the sliding layer, or outgassing from it is prevented or at least reduced. In comparison with the seals or sliding layers from the above-mentioned prior art, it is presumed that in the pump according to the invention the pores of the oxide layer are at least partially filled with the sol-gel-based material of the seal or with fluorine-free polymer. This also seals cross connections between vertical pores, ie the branches arranged horizontally to the layer. This achieves an even shorter running-in time than with the known sliding layers.

In contrast to the state of the art, as in EP 3 153 706 A1 or in EP 3 940 234 A2 described, the polymer-based seal is fluorine-free. "Fluorine-free" describes materials that essentially contain no fluorine. This means that fluorine-containing compounds may be present in the form of impurities or other additives, but these do not significantly change the basic properties of the seal, i.e. the improvement in corrosion protection. Preferably, "fluorine-free" refers to a fluorine content of less than or equal to 100 ppm (= 100 µg/g). The fluorine content can be determined, for example, using X-ray fluorescence measurements.

Furthermore, the present invention relates to a method for coating a pump-active component of a pump. The method according to the invention comprises the following steps: Step A) providing the pump-active component from a light metal workpiece with a porous oxide layer on a surface, Step B) exposing the pump-active component to a negative pressure, Step C) contacting the porous oxide layer with a solution comprising at least one, in particular fluorine-free, polymerizable sealing precursor and/or at least one sol-gel-based sealing precursor, wherein at least during one of the steps A) to C) a voltage is applied to the pump-active part.

The method according to the invention seals the porous oxide structure on the surface of a pump-active component and thus protects it from corrosion. Since a negative pressure is used in the method according to the invention, inclusions are removed from the pores of the oxide structure. This allows the sealing precursor to penetrate better and deeper into the pores. On the other hand, moisture is removed from the oxide layer, which reduces wear on the sealed oxide layer even further.

The light metal workpiece is in particular an aluminium workpiece, e.g. made of one of the aluminium alloys mentioned herein.

By applying a voltage, the sealing precursors are transported into the pores of the oxide layer, so that the pores are very deeply penetrated by the seal. It is assumed that due to this penetration, both horizontal pores and vertical branches are sealed by the method according to the invention. The achievable final pressures and the required run-in times are therefore very low.

The present invention further relates to a pump with a pump-active component, which is obtainable by the method according to the invention.

According to a preferred embodiment of the present invention, the pump according to the invention is preferably a spiral or scroll pump, in particular a spiral or scroll vacuum pump, with conveying elements designed as spiral elements. The sealed oxide layer is particularly preferably provided at least in a tip seal. In this case, the seal is applied at least in regions to at least one of the spiral elements. designed conveying elements. In the case of spiral or scroll pumps, the present invention solves additional problems, such as shortening the run-in time while at the same time achieving low final pressures.

According to an alternative embodiment, the pump according to the invention is a piston pump, in particular a piston vacuum pump. The piston pump has at least one cylinder with an inner cylinder wall and a piston that can move in the cylinder. In this embodiment of the invention, the seal is applied at least in some areas to the inner cylinder wall and/or the piston. Similar to the embodiment of the scroll pump, the seal in the piston pump acts as a sliding layer for the pump-active components. The tightness and the running-in times are thereby shortened.

According to a further preferred embodiment, the pump according to the invention is a turbomolecular pump, wherein the seal is applied at least in some areas to rotor disks and/or stator disks. In conventional porous oxide layers on pump-active components, electrolytic corrosion begins at the pores of the oxide layer. Since the pores of this oxide layer are sealed in the present invention, electrolytic oxidation cannot take place either. The improvement in corrosion resistance therefore improves the longevity of the turbomolecular pump according to this preferred embodiment of the invention.

Preferably, the pump-active component is made of a light metal material. The light metal material is preferably an aluminum alloy, although the present invention is not limited to this. Aluminum alloys of the 4000 series, 5000 series and 6000 series have proven to be particularly suitable, with the aluminum alloys of the 6000 series being particularly preferred. Exemplary representatives for Aluminium alloys of the 6000 series are AIMgSi1 (EN AW-6082) and AlMgSi0.5 (EN AW-6060).

The surface of the pump-active component has an oxide layer. This oxide layer can be formed in different ways. Known methods for this include anodizing, for example. In the present invention, the pump-active component is preferably made of one of the aforementioned aluminum alloys, which is provided with an oxide layer by anodizing in an acid electrolyte. The acid electrolyte can be, for example, a sulfuric acid electrolyte or an oxalic acid electrolyte, whereby the electrolyte can also contain mixtures of these and other acids as well as other additives.

In the pump according to the invention, the layer thickness of the seal is preferably less than or equal to 5 µm, more preferably less than or equal to 3 µm, even more preferably less than or equal to 1 µm. The layer thickness of the seal can be influenced in the production process according to the invention by varying the concentration and type of precursor compound, e.g. an acrylate salt and/or a derivative thereof, by the current intensity and by the duration of the treatment of the pump-active component. This layer thickness can be determined, for example, by means of electron microscope images.

In the method according to the invention, it is preferred if the solution in step C) contains ions and/or ionic compounds. By applying a voltage during the method according to the invention, these ions or ionic compounds can penetrate deep into the pores of the oxide layer in order to then provide the seal there. Due to the deep penetration into the pores, even deep horizontal branches of the porous oxide layer are sealed.

According to Verner, in the process according to the invention, it is preferred that the solution of step C) contains at least one compound, i.e. a precursor compound for forming the seal, with functional groups from the families of organic anions, such as substituted acrylates and/or substituted acetates and/or substituted styrenes and/or substituted isocyanates and/or carboxyls and/or sulfonic acid and/or from the family of inorganic ions, such as silicates, aluminates. Substituted acrylates are particularly preferred. Via the carboxylic acid of the acrylate function, a polymerizable but ionic compound can be transported deep into the pores of the porous oxide layer with the aid of the electrical voltage, so that a deep seal is possible. The solution of step C) therefore particularly preferably comprises salts of acrylic acid and/or salts of acrylic acid derivatives. The salts of acrylic acid and/or acrylic acid derivatives can be dissolved or dispersed in the solution of step C). However, the present invention is not limited to acrylates and their derivatives.

The concentration of the compound having functional groups is preferably in the range of 1.0 to 25 wt.%, more preferably in the range of 3 to 20 wt.%, and even more preferably in the range of 5 to 15 wt.%.

The solution of step C) is preferably an aqueous solution, in particular an aqueous acrylate salt solution in the form of an ionogenic dispersion.

In the present invention, it has proven advantageous to gradually increase the voltage during the treatment of the pump-active component. The voltage is preferably between 40 and 300 V, in particular between 50 and 150 V.

The current density in the process according to the invention is preferably in the range of 0.25 to 20 A/dm ² , more preferably in the range of 0.5 to 15 A/dm ² , still more preferably in the range of 1.0 to 10 A/dm ² , most preferably in the range of 1.5 to 7.0 A/dm ² .

In the method according to the invention, it has been found to be advantageous to apply the voltage to the pump-active component using a direct current. This transports precursors of the seal deep into the pores of the oxide layer in order to form the seal there. The precursor compounds, e.g. an acrylate salt and/or a derivative thereof, are deposited or precipitated within the pores so that the seal forms within the pores. This leads to deep impregnation, which also closes horizontal branches of the porous structure.

According to a preferred embodiment of the method according to the invention, the pump-active component is heat-treated after completion of the electrochemical treatment. The heat treatment is preferably carried out at a temperature in the range from 80 °C to 300 °C, in particular in the range from 100 to 230 °C. During the heat treatment, the seal is formed from the precursors of the seal. Furthermore, due to the heat treatment, moisture in the porous layer of the pump-active component can be reduced, which has a beneficial effect on tribological wear.

In a preferred variant of the present inventive method, the sealing precursor is precipitated in the pores during the electrochemical treatment. In particular in the case of sol-gel-based seals, the sealing precursors, ie a brine, first penetrate into the pores of the oxide layer. Precipitation then occurs simultaneously with the formation of the gel, ie the seal. Since the brine can penetrate very deeply into the pores, the sealing also occurs deep in the pores. This at least partially fills the pores and in particular seals horizontal branches.

According to a further preferred variant of the present inventive method, the sealing precursor is polymerized in the pore. The sealing precursor is present, for example, as a monomer or as a prepolymer and can penetrate deep into the pores of the oxide layer in the form of a solution or dispersion. The polymerization increases the size of the monomers or prepolymers, so that they cause a seal within the pores and remain in the pores. The solubility of the monomers or prepolymers can also change due to the polymerization, so that they precipitate in the pores and cause a deep seal, even of horizontal branches in the porous structure of the oxide layer.

According to a further preferred variant of the present inventive method, in step B) the pump-active component provided in step A) is exposed to a negative pressure, i.e. the negative pressure is applied after the porous oxide layer has been produced. In principle, the porous oxide layer can also be produced under negative pressure. Preferably, the pump-active component is exposed to the further process without further drying after the oxide layer has been produced. If drying takes place after the oxide layer has been produced, e.g. by anodizing, the pores can be closed by natural oxidation, which impairs the quality of the seal. Therefore, after the oxide layer has been produced on the surface of the pump-active component, the further process is preferably carried out without further drying and/or storage. In other words, the sealing is preferably carried out wet-on-wet, i.e. only with an optional rinsing between the production of the oxide layer, e.g. by anodizing, and the further process.

The method according to the invention is preferably part of the manufacture of a pump, in particular a vacuum pump, as described herein.

According to a preferred variant of the present invention, the pump according to the invention with a pump-active component that is obtainable by the method described herein is a pump with all the details that are also described herein independently of the method according to the invention for pumps.

Fig. 1

zeigt eine Scrollpumpe in einer Schnittansicht.

Fig. 2

zeigt ein Elektronikgehäuse der Scrollpumpe.

Fig. 3

zeigt die Scrollpumpe in perspektivischer Ansicht, wobei ausgewählte Elemente freigestellt sind.

Fig. 4

zeigt einen in die Pumpe integrierten Drucksensor.

Fig. 5

zeigt ein bewegliches Spiralbauteil der Pumpe.

Fig. 6

zeigt das Spiralbauteil von einer anderen, der in Fig. 5 sichtbaren Seite gegenüberliegenden Seite.

Fig. 7

zeigt eine Einspannvorrichtung für ein Spiralbauteil.

Fig. 8 und 9

zeigen jeweils eine Exzenterwelle mit einem Ausgleichsgewicht von unterschiedlichen Scrollpumpen.

Fig. 10

zeigt ein Gasballastventil mit einem Betätigungsgriff in perspektivischer Ansicht.

Fig. 11

zeigt das Ventil der Fig. 10 in einer Schnittansicht.

Fig. 12

zeigt einen Teilbereich des Spiralbauteils der Fig. 5 und 6.

Fig. 13

zeigt einen Querschnitt des Spiralbauteils durch die Spiralwand in einem äußeren Endbereich.

Fig. 14

zeigt eine Luftleithaube der Scrollpumpe der Fig. 1 in perspektivischer Ansicht.

Fig. 15

zeigt ein Abdrückgewinde in einer Schnittdarstellung.

Fig. 16

zeigt eine Detaildarstellung der Spiral- oder Scrollpumpe aus Fig. 1.

Fig. 17

zeigt eine elektronenmikroskopische Querschnittsansicht einer Oxidschicht.

Fig. 18

zeigt eine stärker vergrößerte elektronenmikroskopische Querschnittsansicht der Oxidschicht von Fig. 16.

Fig. 19

zeigt eine elektronenmikroskopische Aufsicht auf die Oxidschicht von Fig. 16 und 17.

Fig. 20

zeigt die Entwicklung des Vakuums bei Einsatz einer Scrollpumpe mit unterschiedlich beschichteten bzw. unbeschichteten Förderelementen.

Fig. 21

zeigt eine perspektivische Ansicht einer Turbomolekularpumpe.

Fig. 22

zeigt eine Ansicht der Unterseite der Turbomolekularpumpe von Fig. 21.

Fig. 23

zeigt einen Querschnitt der Turbomolekularpumpe längs der in Fig. 22 gezeigten Schnittlinie A-A.

Fig. 24

zeigt eine Querschnittsansicht der Turbomolekularpumpe längs der in Fig. 22 gezeigten Schnittlinie B-B.

Fig. 25

zeigt eine Querschnittsansicht der Turbomolekularpumpe längs der in Fig. 22 gezeigten Schnittlinie C-C.

The invention is explained below merely by way of example with reference to the schematic drawings and the examples.

Fig.1

shows a scroll pump in a sectional view.

Fig.2

shows an electronic housing of the scroll pump.

Fig.3

shows the scroll pump in perspective view, with selected elements isolated.

Fig.4

shows a pressure sensor integrated into the pump.

Fig.5

shows a movable spiral component of the pump.

Fig.6

shows the spiral component of another, which in Fig.5 visible side opposite side.

Fig.7

shows a clamping device for a spiral component.

Fig. 8 and 9

each show an eccentric shaft with a counterweight from different scroll pumps.

Fig.10

shows a gas ballast valve with an operating handle in perspective view.

Fig. 11

shows the valve of the Fig.10 in a sectional view.

Fig. 12

shows a section of the spiral component of the Fig. 5 and 6 .

Fig. 13

shows a cross-section of the spiral component through the spiral wall in an outer end region.

Fig. 14

shows an air guide hood of the scroll pump of the Fig.1 in perspective view.

Fig. 15

shows a forcing thread in a sectional view.

Fig. 16

shows a detailed view of the spiral or scroll pump from Fig.1 .

Fig. 17

shows an electron microscopic cross-sectional view of an oxide layer.

Fig. 18

shows a higher magnification electron microscopic cross-sectional view of the oxide layer of Fig. 16 .

Fig. 19

shows an electron microscopic view of the oxide layer of Fig. 16 and 17 .

Fig. 20

shows the development of the vacuum when using a scroll pump with differently coated or uncoated conveying elements.

Fig. 21

shows a perspective view of a turbomolecular pump.

Fig. 22

shows a view of the bottom of the turbomolecular pump from Fig. 21 .

Fig. 23

shows a cross section of the turbomolecular pump along the Fig. 22 shown section line AA.

Fig. 24

shows a cross-sectional view of the turbomolecular pump along the Fig. 22 shown cutting line BB.

Fig. 25

shows a cross-sectional view of the turbomolecular pump along the Fig. 22 shown cutting line CC.

Although the present invention is not applicable to scroll pumps 20 as described in Fig. 1 to 16 shown as an example, it has proven to be very suitable for this purpose. In principle, the pump according to the invention can also be a turbomolecular pump (see the exemplary description based on the Fig. 21 to 25 ) or a piston pump (not shown in the figures).

The Fig.1 shows a vacuum pump designed as a scroll pump 20. This comprises a first housing element 22 and a second housing element 24, the second housing element 24 having a pump-active structure, namely a spiral wall 26. The second housing element 24 thus forms a fixed spiral component of the scroll pump 20. The spiral wall 26 interacts with a spiral wall 28 of a movable spiral component 30, the movable spiral component 30 being eccentrically excited via an eccentric shaft 32 to generate a pumping effect. A gas to be pumped is conveyed from an inlet 31, which is defined in the first housing element 22, to an outlet 33, which is defined in the second housing element 24.

The eccentric shaft 32 is driven by a motor 34 and supported by two roller bearings 36. It comprises an eccentric pin 38 arranged eccentrically to its axis of rotation, which transmits its eccentric deflection to the movable spiral component 30 via a further roller bearing 40. The movable spiral component 30 also has a Fig.1 left-hand end of a bellows 42, the right-hand end of which is attached to the first housing element 22. The left-hand end of the bellows 42 follows the deflection of the movable spiral component 30.

The scroll pump 20 comprises a fan 44 for generating a cooling air flow. An air guide hood 46 is provided for this cooling air flow, to which the fan 44 is also attached. The air guide hood 46 and the housing elements 22 and 24 are shaped in such a way that the cooling air flow essentially flows around the entire pump housing and thus achieves good cooling performance.

The scroll pump 20 further comprises an electronics housing 48 in which a control device and power electronics components for driving the motor 34 are arranged. The electronics housing 48 also forms a base for the pump 20. Between the electronics housing 48 and the first housing element 22, a channel 50 is visible through which an air flow generated by the fan 44 is guided along the first housing element 22 and also along the electronics housing 48, so that both are effectively cooled.

The electronics housing 48 is in Fig.2 It comprises several separate chambers 52. Electronic components can be encapsulated in these chambers 52 and are thus advantageously shielded. Preferably, the smallest possible amount of encapsulation material can be used when encapsulating the electronic components. For example, the encapsulation material can first be introduced into the chamber 52 and then the electronic component can be pressed in. Preferably, the chambers 52 can be designed so be designed so that different variants of the electronic components, in particular different assembly variants of a circuit board, can be arranged in the electronic housing 48 and/or can be encapsulated. For certain variants, individual chambers 52 can also remain empty, i.e. have no electronic components. In this way, a so-called modular system for different pump types can be implemented in a simple manner. The encapsulation material can in particular be designed to be heat-conducting and/or electrically insulating.

At a related Fig. 2 A number of walls or ribs 54 are formed on the rear side of the electronics housing 48, which define a number of channels 50 for conducting a cooling air flow. The chambers 52 also enable particularly good heat dissipation from the electronic components arranged in them, in particular in conjunction with a heat-conducting potting material, and towards the ribs 54. The electronic components can thus be cooled particularly effectively and their service life is improved.

In Fig.3 the scroll pump 20 is shown as a whole in perspective, but the air guide hood 46 is hidden so that the fixed spiral component 24 and the fan 44 in particular are visible. The fixed spiral component 24 has a plurality of recesses 56 arranged in a star shape, each of which defines ribs 58 arranged between the recesses 56. The cooling air flow generated by the fan 44 leads through the recesses 56 and past the ribs 58 and thus cools the fixed spiral component 24 particularly effectively. The cooling air flow first flows around the fixed spiral component 24 and only then around the first housing element 22 or the electronics housing 48. This arrangement is particularly advantageous because the pump-active area of the pump 20 develops a lot of heat due to the compression during operation and is therefore primarily cooled here.

The pump 20 comprises a pressure sensor 60 integrated therein. This is arranged inside the air guide hood 46 and screwed into the fixed spiral component 24. The pressure sensor 60 is connected to the electronics housing 48 and a control device arranged therein via a cable connection (only partially shown). The pressure sensor 60 is integrated into the control of the scroll pump 20. For example, the motor 34, which is in Fig.1 visible, depending on a pressure measured by the pressure sensor 60. For example, when using the pump 20 in a vacuum system as a backing pump for a high vacuum pump, the high vacuum pump can only be switched on if the pressure sensor 60 measures a sufficiently low pressure. In this way, the high vacuum pump can be protected from damage.

Fig.4 shows the pressure sensor 60 and its arrangement on the fixed spiral component 24 in a cross-sectional view. A channel 62 is provided for the pressure sensor 60, which here opens into a non-pumping outdoor area between the spiral walls 26 and 28 of the fixed or movable spiral components 24 and 30. The pressure sensor thus measures a suction pressure of the pump. Alternatively or additionally, for example, a pressure between the spiral walls 26 and 28 in a pumping active area can also be measured. Depending on the position of the pressure sensor 60 or the channel 62, intermediate pressures can also be measured, for example.

The pressure sensor 60 allows, for example by determining a compression, in particular a detection of a state of wear of the pump-active components, in particular of a sealing element 64 also referred to as a tip seal. Furthermore, the measured intake pressure can also be used to regulate the pump (including pump speed). For example, an intake pressure can be specified by software and an intake pressure can be set by varying the pump speed. It is also conceivable that, depending on the measured pressure, a pressure increase due to wear can be compensated by increasing the speed. This means that a tip seal change can be postponed or longer change intervals can be implemented. The data from the pressure sensor 60 can therefore generally be used, for example, to determine wear, to control the pump in a given situation, for process control, etc.

The pressure sensor 60 can be provided optionally, for example. Instead of the pressure sensor 60, a blind plug can be provided for closing the channel 62. A pressure sensor 60 can then be retrofitted if necessary, for example. Particularly with regard to retrofitting, but also generally advantageous, it can be provided that the pressure sensor 60 is automatically recognized when connected to the control device of the pump 20.

The pressure sensor 60 is arranged in the cooling air flow of the fan 44. This also advantageously cools it. This also means that no special measures need to be taken to increase the temperature resistance of the pressure sensor 60 and, consequently, a cost-effective sensor can be used.

In addition, the pressure sensor 60 is arranged in particular in such a way that the external dimensions of the pump 20 are not increased by it and the pump 20 consequently remains compact.

In the Fig. 5 and 6 the movable spiral component 30 is shown in different views. In Fig.5 the spiral structure of the spiral wall 28 is particularly clearly visible. In addition to the spiral wall 28, the spiral component 30 comprises a base plate 66 from which the spiral wall 28 extends.

A side of the base plate 66 facing away from the spiral wall 28 is in Fig.6 visible. On this side, the base plate includes several Fastening recesses, for example for fastening the bearing 40 and the bellows 42, which are in Fig.1 are visible.

On the outside of the base plate 66, there are three retaining projections 68 that are spaced apart and evenly distributed over the circumference of the base plate 66. The retaining projections 68 extend radially outwards. In particular, the retaining projections 68 all have the same radial height.

A first intermediate section 70 of the circumference of the base plate 66 extends between two of the holding projections 68. This first intermediate section 70 has a greater radial height than a second intermediate section 72 and than a third intermediate section 74. The first intermediate section 70 is arranged opposite an outermost 120° section of the spiral wall 28.

When manufacturing the movable spiral component 30, the base plate 66 and the spiral wall 28 are preferably manufactured together from a solid material, i.e. the spiral wall 28 and the base plate 66 are formed as one piece.

For example, during finishing machining, the spiral component 30 can be clamped directly to the holding projections 68. Within the scope of one and the same clamping, for example, the Fig.6 shown side of the base plate 66 are machined, in particular the fastening recesses are made. In principle, the spiral wall 28 can also be machined from the solid material within the scope of this clamping.

For this purpose, the spiral component 30 can be clamped, for example, with a clamping device 76 as shown in Fig.7 This has a hydraulic three-jaw chuck 78 for direct contact with the three retaining projections 68. In addition, the clamping device 76 has a continuous recess 80, through which a tool access to the spiral component 30, in particular to the Fig.6 shown side thereof. Thus, machining operations can be carried out from both sides during clamping, in particular at least a finishing machining of the spiral wall 28 and the introduction of fastening recesses.

The contour of the retaining projections 68 and the clamping pressure of the clamping device 76 are preferably selected so that no critical deformations of the spiral component 30 occur. The three retaining projections 68 are preferably selected so that the external dimension, i.e. the maximum diameter of the spiral component 30, is not increased. This allows material to be saved on the one hand and machining volume to be saved on the other. The retaining projections 68 are in particular designed and/or arranged at such an angular position that the screw connection of the corrugated bellows 42 is accessible. The number of screw connection points of the corrugated bellows 42 is preferably not equal to the number of retaining projections 68 on the movable spiral component 30.

On the eccentric shaft 32 of the Fig.1 Two balancing weights 82 are attached to compensate for any imbalance of the excited system. The area of the Fig.1 right-hand balance weight 82 is in Fig.8 shown enlarged. The balancing weight 82 is screwed to the eccentric shaft 32.

A similar image section is in Fig.9 for another scroll pump, preferably of the same series as pump 20 of the Fig.1 The Fig.9 The underlying pump has different dimensions and therefore requires a different balancing weight 82.

The eccentric shafts 32, the balancing weights 82 and the housing elements 22 are dimensioned such that at the mounting position shown only one certain type of the two shown types of balancing weights 82 can be mounted on the eccentric shaft 32.

The balancing weights 82 are in the Fig. 8 and 9 together with certain dimensions of the installation space provided for it, in order to clarify that the balancing weight 82 of the Fig.9 cannot be mounted on the eccentric shaft 32 and vice versa. It is understood that the dimensions given are purely examples.

In Fig.8 a distance between a mounting hole 84 and a shaft shoulder 86 9.7 mm. The balancing weight 82 of the Fig.8 is shorter in the corresponding direction, namely 9 mm long, so it can be installed without any problems. The balance weight 82 of the Fig.9 has a longitudinal extension of 11 mm measured from the mounting hole. Thus, the balancing weight 82 of the Fig.9 not on the eccentric shaft 32 of the Fig.8 cannot be mounted because the shaft shoulder 86 collides with the balance weight 82 during an attempted assembly or because the balance weight 82 of the Fig.9 not fully aligned with the eccentric shaft 82 of the Fig.8 Because the balance weight 82 of the Fig.9 in both dimensions is greater than the distance between mounting hole 84 and shaft shoulder 86 in Fig.8 , installation in the opposite direction is also prevented. In addition, the dimension of 21.3 mm of the balance weight 82 of the Fig.8 an inverted and consequently incorrect mounting orientation of the otherwise correct balancing weight 82.

In Fig.9 The distance in the longitudinal direction between the mounting hole 84 and a housing shoulder 88 is 17.5 mm. The counterweight 82 of the Fig.8 with its extension of 21.3 mm, when inserting the eccentric shaft 32 of the Fig.9 collide with the housing shoulder 88, so that complete assembly would not be possible. Incorrect assembly is initially possible, but reliably detected. If the balancing weight 82 of the Fig.8 on the eccentric shaft 32 of the Fig.9 the extension of 21.3 mm would collide with the shaft shoulder 86, which is arranged only at a distance of 13.7 mm from the fastening hole 84.

The balancing weights 82, in particular a motor-side balancing weight 82, are generally designed in such a way that confusion of the balancing weight with those of other sizes is avoided during assembly and/or servicing. The balancing weights are preferably attached using through-bolts. Similar balancing weights of different pump sizes are in particular designed in such a way that installation of the wrong balancing weight is prevented due to adjacent shoulders on the shaft, the positions of the thread and through-hole of the balancing weight and shoulders within the housing.

In the Figs. 10 and 11 a gas ballast valve 90 of the scroll pump 20 is shown. This is also shown in the overall view of the pump 20 in Fig.3 visible and arranged on the fixed spiral component 24.

The gas ballast valve 90 comprises an actuating handle 92. This comprises a plastic body 94 and a base element 96, which is preferably made of stainless steel. The base element 96 comprises a through-hole 98, which is provided on the one hand for connecting and introducing a ballast gas and on the other hand comprises a check valve 100. The hole 98 is also closed in the illustrations by means of a plug 102. Instead of the plug 102, a filter can also be provided, for example, wherein the ballast gas can preferably be air and enters the valve 90 directly via the filter.

The operating handle 92 is attached to a rotatable element 106 of the valve 90 by means of three fastening screws 104, which are arranged in a respective bore 108 and of which in the selected sectional view of the Fig. 11 only one is visible. The rotatable element 106 is rotatably attached to the second housing element 24 by means of a fastening screw (not shown) which runs through a bore 110.

To operate the valve 90, a torque applied manually to the operating handle 92 is transmitted to the rotatable element 106, thus rotating it. The bore 98 thus comes into communication with the interior of the housing. Three switching positions are provided for the valve 90, namely the Fig.10 shown, which is a locking position, and a position rotated to the right and to the left, in which the bore 98 is in communication with different areas of the interior of the housing.

The holes 108 and 110 are closed by a cover 112. The sealing effect of the gas ballast valve 90 is based on axially pressed O-rings. When the valve 90 is actuated, a relative movement is exerted on the O-rings. If contaminants, such as particles, get onto the surface of an O-ring, this poses the risk of premature failure. The cover 112 prevents contaminants and the like from penetrating the screws of the handle 92.

This cover 112 is attached via an interference fit of three centering elements. Specifically, the cover 112 has a plug-in pin (not shown) for each hole 108, with which the cover 112 is held in the holes 108. The holes 108 and 110 and the fastening screws arranged therein are thus protected from contamination. In particular, with the fastening screw (not shown) arranged in the hole 110, which allows a rotary movement, contamination can thus be prevented from entering the Valve mechanics can be effectively minimized and thus the service life of the valve can be improved.

The plastic handle with overmolded stainless steel base ensures good corrosion resistance while keeping manufacturing costs low. Furthermore, the plastic of the handle stays cooler due to the limited heat conduction and is therefore easier to use.

For the fan 44, as used for example in the Fig.1 and 3 is visible, a speed control is preferably provided. The fan is controlled by means of PWM depending on the power consumption and temperature of the power module, which is housed in the electronics housing 48, for example. The speed is set in line with the power consumption. However, control is only permitted when the module temperature is above 50 °C. If the pump enters temperature ranges of possible derating (temperature-related power reduction), the max. fan speed is automatically controlled. This control makes it possible to achieve a minimum noise level when the pump is cold, to ensure a low noise level at final pressure or at low load - corresponding to the pump noise, to achieve optimal cooling of the pump with a low noise level at the same time, and to ensure the maximum cooling capacity before a temperature-related power reduction.

The maximum fan speed can be adjusted, especially depending on the situation. For example, if a system has a high tolerance to water vapor, it may be useful to reduce the maximum fan speed.

In Fig. 12 the movable spiral component 30 is partially and opposite Fig.5 enlarged. A sectional view of the spiral component 30 along the Fig. 12 indicated line A:A is in Fig. 13 shown schematically and not to scale.

The spiral wall 28 has a groove 114 at its end facing away from the base plate 66 and facing a base plate of the fixed spiral component 24 (not shown here) for inserting a sealing element 64 (also not shown here), namely a so-called tip seal. The arrangement in the operating state is shown, for example, in Fig.4 clearly visible. According to a preferred embodiment of the pump according to the invention, a tip seal is provided which is in sliding contact with the sliding layer, ie the sealed oxide layer.

The groove 114 is delimited to the outside and to the inside by two opposite side walls, namely by an inner side wall 116 and an outer side wall 118. In a first spiral section 120, the outer side wall 118 is thicker than the inner side wall 116 in the first spiral section 120 and thicker than both side walls 116 and 118 in another, second spiral section 122.

The first spiral section 120 extends from Fig. 12 indicated place to the outer end of the spiral wall 28, as is also the case in Fig.5 is indicated. The first spiral section 120 extends here, for example, over approximately 163°.

The first spiral section 120 forms an outer end section of the spiral wall 28. The first spiral section 120 is arranged at least partially, in particular completely, in a non-pumping area of the spiral wall 28. In particular, the first spiral section 120 can at least substantially completely fill the non-pumping area of the spiral wall 28.

As it is in Fig.5 visible, preferably the first intermediate section 70 between two retaining projections 68, which has a greater radial height than other intermediate sections 72 and 74, the first spiral section 120 be arranged opposite one another. An imbalance introduced by the thicker side wall 118 can thus be compensated by the greater weight of the first intermediate section 70.

To keep the system load on the bearings and other components low, the moving spiral component should preferably have a low dead weight. The spiral walls are therefore generally very thin. Furthermore, thinner walls result in smaller pump dimensions (significant outer diameter). The side walls of the tip seal groove are therefore particularly thin. The ratio of the tip seal wall thickness to the total spiral wall thickness is, for example, a maximum of 0.17. However, due to the tip seal groove, the spiral wall tip is very sensitive to impacts during handling, such as during assembly or when changing the tip seal. Light impacts, e.g. during transport, can push the side wall of the groove inwards so that the tip seal can no longer be installed. To solve this problem, the groove has an asymmetrical wall thickness, in particular a local thickening of the spiral wall towards the outside. This area is preferably not pump-active and can therefore be manufactured with a larger tolerance. The one-sided thickening on the, particularly the last half, turn significantly reduces damage. At other parts of the component, it is preferably not necessary to thicken the spiral wall, since the wall is protected by protruding elements of the component.

In the Fig.1 The air guide hood 46 shown defines an air flow, as indicated by a dashed arrow 124. The fan 44 is connected to a control device in the electronics housing 48 via a cable (not shown) which runs through the air guide hood 46, and via a plug connection. This comprises a socket 126 and a plug 128. The socket 126 is mounted on the electronics housing 48 and/or attached to a circuit board arranged in the electronics housing 48. The socket 126 is also provided, for example, in the Fig.2 and 3 visible. The connector 128 is connected to the fan 44 via the cable not shown.

The plug connection 126, 128 is separated from the air flow 124 by a partition 130. The air flow 124, which may contain dust or similar contaminants, for example, is thus kept away from the plug connection 126, 128. This protects the plug connection 126, 128 itself on the one hand, and prevents contaminants from entering the electronics housing 48 through the opening provided for the socket 126 and reaching the control device and/or power electronics on the other.

The air guide hood 46 is in Fig. 14 shown separately and in perspective. Among other things, the partition wall 130 with the space defined behind it for the plug 128 is visible. The partition wall 130 comprises a recess 132, designed here as a V-shaped notch, for passing a cable from the plug 128 to the fan 44.

For example, to save costs, inexpensive connectors without sealing (e.g. no IP protection) can be used, since the partition 130 ensures that the air drawn in does not reach the electronics via the opening in the connector 126, 128. The fan cable is guided through the V-shaped notch 132 at the side through the partition 130. The notch 132 has a lateral offset to the connector 126, 128, which creates a labyrinth effect and thus further reduces the leakage of cooling air to the connector 126, 128. A partition 130 within the air guide hood 46 also improves the air flow into the channel 50 between the electronics housing 48 and the pump housing 22. There is less turbulence and back pressure for the fan 44.

The Fig. 15 shows a contact area between the first housing element 22 and the second housing element or fixed spiral component 24 in a schematic sectional view. The second housing element 24 is partially inserted into the first housing element 22 with a transition fit 134. A seal is provided by means of an O-ring 136. The transition fit 134 also serves, for example, to center the second housing element 24 relative to the first housing element 22.

For maintenance purposes, for example to replace the sealing element 64, the second housing element 24 must be dismantled. In doing so, it may happen that the transition fit 134 or the O-ring 136 jams if the second housing element 24 is not pulled out straight enough. To solve this problem, a forcing thread 138 is provided. Preferably, a second forcing thread can also be provided at least substantially radially opposite. To release the second housing element 24 as straight and guided as possible, a screw can be screwed into the forcing thread 38 until the screw protrudes from it and comes into contact with the first housing element 22. By screwing in further, the housing elements 22 and 24 are pressed away from each other.

For example, the fastening screws 142 provided for fastening the second housing element 24 to the first housing element 22 can be used for pressing, as shown for example in the Fig.1 and 3 For this purpose, the forcing thread 138 preferably has the same type of thread as the fastening thread provided for the fastening screws 142.

A countersink 140 is provided on the second housing element 22, which is associated with the forcing thread 138. If abrasion particles are discharged when the screw is screwed into the forcing thread 138, they collect in the recess 140. This prevents such abrasion particles from, for example, preventing the housing elements 22 and 24 from fully engaging one another.

When assembling the fixed spiral component 24, the screws must be unscrewed again, otherwise a complete screwing (correct fit on the flat surface of the housing) of the fixed spiral component 24 on the first housing element 22 may be prevented. Leakage, misalignment and a reduction in pump performance can be the result. To avoid this assembly error, the air guide hood 46 has at least one, in particular additional, Fig. 14 shown dome 144, which only allows the air guide hood 46 to be mounted when the screws used for forcing, in particular the fastening screws 142, have been removed again. This is because the air guide hood 46 with the dome 144 is designed in such a way that it would collide with a screw head of a forcing screw that might be screwed into the forcing thread 138, so that the air guide hood 46 could not be fully mounted. In particular, the air guide hood 46 can only be mounted when the forcing screws are completely removed.

Fig. 16 shows a schematic detail of the spiral or scroll pump 20 according to the previous figures, in the area where the seal 150 touches the carrier 154 in the form of the base plate 66, which is provided with the sliding layer 152, i.e. the sealed oxide layer. In particular, the arrangement of the spiral elements 26, 28 is such that the seal 150 is pressed against the carrier 154, in the form of the base plate 66. The seal is pressed against the base plate via the pressure difference between both sides of the spiral elements 26, 28. The seal 150 is connected to the spiral elements 26, 28 via an interface 151. The oxide layer and the sealing of the sliding layer 152 are not shown separately, since the sealing has penetrated into the pores and defects in the oxide layer and closes them. An additional layer structure does not necessarily take place. The preferably fluorine-free sealing not only promotes the dry lubrication properties of the sliding layer 152 and additionally reduces its wear, but also improves the gas-tightness of the sliding layer 152, which results in an improvement in the achievable final pressures and a shortening of the running-in time.

The supports 154, in the form of the base plate 66, and the spiral walls 26, 28 are each formed in one piece and consist of an aluminum alloy of the type AlMgSi. The oxide layer of the sliding layer 152 is an aluminum oxide layer produced by anodic oxidation in a sulfuric acid electrolyte. The sliding layer 152 is applied in particular to all surfaces of the spiral components 24, 30 facing the conveying chambers. In the Fig.6 For example, the seal 150 (Tip Seals) shown is an acrylate-based fluorine-free polymer.

The pump according to the invention can have one or more of the features described above with reference to the Figures 1 to 16 described features, whereby any combination of these features can be realized in a pump according to the invention.

In Fig. 17 is an electron micrograph of a cross-section showing an oxide layer 156 with a thickness of 39.08 µm, which is applied to a base plate 66. The scale in Fig. 17 shows a length of 10 µm. The oxide layer 156 has cracks 158 and defects 158, which impair the gas tightness. A further enlarged view is shown in Fig. 18 where the pore structure as well as the defects connecting the pores are visible. The scale in Fig. 18 shows a length of 200 nm. The porous structure of the oxide layer 156 can also be seen from Fig. 19 which shows an electron microscopic view of the oxide layer of Fig. 17 and Fig. 18 , with the pores 160 appearing as dark, vertical stripes, and very small defects 158 can be seen as dark spots that connect neighboring pores 160. The scale in Fig. 18 shows a length of 200 nm. Very small pores 160 as well as larger pores 160 as well as cracks 158 and their branches can be seen. In Figures 17 to 19, only a few pores and defects are marked with reference symbols.

The effect of the sliding layer of the pump according to the invention is based on the Fig. 20 shown graphs. The time in hours is plotted on the abscissa axis (X-axis), and the pressure in hPa on the ordinate axis. Under identical conditions, a negative pressure was generated using scroll vacuum pumps, and the development of the respective negative pressure was recorded over time.

All lines A to D were equipped with a HiScroll pump, the only difference being that the conveying elements in line A have no coating. In line B, the conveying elements have a coating as shown in EP 3 153 706 A1 described coating, whereby a sulphuric acid electrolyte was used to produce the oxide layer, ie an anodically produced oxide layer. Line C shows the development of the vacuum with a sealed sliding layer based on a fluorine-containing polymer, as in EP 3 940 234 A2 describe. Line D shows the development of the vacuum with a vacuum pump according to the invention, in which the oxide layer is additionally provided with a fluorine-free polymer-based seal based on acrylate. The sealing of the oxide layer of line D was produced as described in the following example.

As can be seen from line A, a low final pressure can be achieved very quickly with uncoated conveying elements, but this is not stable due to wear of the conveying elements. A stable, but even after A relatively high final pressure can be achieved after a long running-in phase if the conveying elements have an anodic coating. This is clear from line B. With the pump on line B, the test was interrupted after a short running time and a seal was applied to the oxide layer. When the test is continued, it is noticeable that the pressure drops much more quickly and a much lower final pressure is reached. Line C shows that a lower final pressure can be achieved with the fluorine-containing seal known from the prior art, but there is still the need for a certain running-in phase and the disadvantage of using fluorine-containing components which, due to their stability in nature, may not be ideal for environmental reasons. The sealed conveying elements as used in line D, i.e. in a pump according to the invention, enable a much lower final pressure than in line B (until the test is interrupted), whereby the vacuum achieved is stable, unlike in line A. With lines B and C, a much longer running-in period is to be expected until the lower final pressures are reached. With the sealing according to the invention, not only is an excellent final pressure achieved, but the run-in time is also significantly reduced. This illustrates the remarkable effects achieved by sealing the pore structure of the oxide layer in terms of short run-in times, low final pressures and high corrosion and wear resistance.

However, the pump according to the invention can also be a turbomolecular pump as described in the Fig. 21 to 25 is generally described.

In the Fig. 21 The turbomolecular pump 111 shown comprises a pump inlet 115 surrounded by an inlet flange 113, 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.

The inlet flange 113 forms the vacuum pump in the alignment according to Fig. 21 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 on the side. Electrical and/or electronic components of the vacuum pump 111 are housed in the electronics housing 123, e.g. for operating an electric motor 125 arranged in the vacuum pump (see also Fig. 23 ). Several connections 127 for accessories are provided on the electronics housing 123. In addition, a data interface 129, e.g. according to the RS485 standard, and a power supply connection 131 are arranged on the electronics housing 123.

There are also turbomolecular pumps that do not have such an attached electronics housing, but are connected to external drive electronics.

A flood inlet 133, in particular in the form of a flood valve, is provided on the housing 119 of the turbomolecular pump 111, via which the vacuum pump 111 can be flooded. In the area of the lower part 121, a sealing gas connection 135, which is also referred to as a purge gas connection, is also arranged, via which purge gas can be fed to protect the electric motor 125 (see e.g. Fig. 23 ) can be let into the motor compartment 137, in which the electric motor 125 is housed in the vacuum pump 111, before the gas delivered by the pump. In the lower part 121, two coolant connections 139 are also arranged, one of the coolant connections being provided as an inlet and the other coolant connection as an outlet for coolant that can be fed into the vacuum pump for cooling purposes. Other existing turbomolecular vacuum pumps (not shown) are operated exclusively with air cooling.

The lower side 141 of the vacuum pump can serve as a base so that the vacuum pump 111 can be operated standing on the underside 141. The vacuum pump 111 can also be attached to a recipient via the inlet flange 113 and thus operated in a hanging position. In addition, the vacuum pump 111 can be designed in such a way that it can also be put into operation when it is aligned in a different way than in Fig. 21 is shown. It is also possible to realize embodiments of the vacuum pump in which the underside 141 is not arranged facing downwards, but to the side or facing upwards. In principle, any angle is possible.

Other existing turbomolecular vacuum pumps (not shown), which are particularly larger than the pump shown here, cannot be operated in an upright position.

On the underside 141, which is in Fig. 22 As shown, various screws 143 are arranged, by means of which components of the vacuum pump (not further specified here) are fastened to one another. For example, a bearing cover 145 is fastened to the underside 141.

Mounting holes 147 are also arranged on the underside 141, via which the pump 111 can be attached to a support surface, for example. This is not possible with other existing turbomolecular vacuum pumps (not shown), which are in particular larger than the pump shown here.

In the Figures 22 to 25 a coolant line 148 is shown in which the coolant introduced and discharged via the coolant connections 139 can circulate.

As the sectional views of the Figures 23 to 25 show, the vacuum pump comprises several process gas pumping 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 a rotation axis 151.

The turbomolecular pump 111 comprises several turbomolecular pump stages connected in series with a pumping effect, with several radial rotor disks 155 attached 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 pump 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 arranged one inside the other in the radial direction and connected in series to pump with one another. There are other turbomolecular vacuum pumps (not shown) that do not have Holweck pump stages.

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 fastened to and supported by the rotor hub 161 and which are oriented coaxially to the rotation axis 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 rotation axis 151 and are nested in one another in the radial direction.

The pumping surfaces of the Holweck pump stages are formed by the shell surfaces, i.e. 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 opposite the radial outer surface of the outer Holweck rotor sleeve 163, forming a radial Holweck gap 171, and with this forms the first Holweck pumping stage following the turbomolecular pumps. The radial inner surface of the outer Holweck rotor sleeve 163 lies opposite the radial outer surface of the inner Holweck stator sleeve 169, forming a radial Holweck gap 173, and with this forms 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, forming a radial Holweck gap 175, and with this forms the third Holweck pumping stage.

A radially extending channel can be provided at the lower end of the Holweck rotor sleeve 163, via which the radially outer Holweck gap 171 is connected to the middle Holweck gap 173. In addition, a radially extending 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 above-mentioned pump-active surfaces of the Holweck stator sleeves 167, 169 each have a plurality of Holweck grooves running spirally around the rotation axis 151 in the axial direction, while the opposite lateral surfaces of the Holweck rotor sleeves 163, 165 are smooth and propel the gas in the Holweck grooves for operating the vacuum pump 111.

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

In the area of the roller bearing 181, a conical spray nut 185 with an outer diameter that increases towards the roller bearing 181 is provided on the rotor shaft 153. The spray nut 185 is in sliding contact with at least one scraper of a fluid reservoir. In other existing turbomolecular vacuum pumps (not shown), a spray screw can be provided instead of a spray nut. Since different designs are thus possible, the term "spray tip" is also used in this context.

The operating fluid storage comprises several absorbent disks 187 stacked on top of each other, which are impregnated with an operating fluid for the rolling bearing 181, e.g. with a lubricant.

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

The permanent magnet 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 magnet rings 195, 197 stacked on top of one another in the axial direction. The ring magnets 195, 197 lie opposite one another to form a radial bearing gap 199, with 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 repulsion forces between the ring magnets 195, 197, which cause a radial bearing of the rotor shaft 153. The rotor-side ring magnets 195 are supported by a support section 201 of the rotor shaft 153, which surrounds the ring magnets 195 radially on the outside. The stator-side ring magnets 197 are supported 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 rotor-side ring magnets 195 are fixed parallel to the rotation axis 151 by a cover element 207 coupled to the support section 201. The stator-side ring magnets 197 are fixed parallel to the rotation axis 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 disc spring 213 can also be provided between the fastening ring 211 and the ring magnets 197.

An emergency or safety bearing 215 is provided within the magnetic bearing, which runs idle without contact during normal operation of the vacuum pump 111 and only engages when there is an excessive radial deflection of the rotor 149 relative to the stator in order to form a radial stop for the rotor 149 so that a collision of the rotor-side structures with the stator-side structures is prevented. The safety bearing 215 is designed as an unlubricated roller bearing and forms a radial gap with the rotor 149 and/or the stator, which causes the safety bearing 215 to be disengaged during normal pumping operation. The radial deflection at which the safety bearing 215 engages is large enough so that the safety bearing 215 does not engage 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 is prevented under all circumstances.

The vacuum pump 111 comprises the electric motor 125 for rotating the rotor 149. The armature of the electric motor 125 is formed by the rotor 149, whose rotor shaft 153 extends through the motor stator 217. A permanent magnet arrangement can be arranged radially on the outside or embedded in 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 extending through the motor stator 217 there is an intermediate space 219 which comprises a radial motor gap, via which the motor stator 217 and the permanent magnet arrangement can magnetically influence each other to transmit the drive torque.

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 purge gas and which can be air or nitrogen, for example, can enter the motor 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 motor compartment 137 can also be evacuated via the pump outlet 117, i.e. the vacuum pressure in the motor compartment 137 is at least approximately the vacuum pressure caused by the forevacuum pump connected to the pump outlet 117.

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

The sealing of a porous oxide layer is described below by way of example. It is understood that the following description is for illustrative purposes only and does not limit the invention in any way.

A pump-active component of a scroll vacuum pump made of an aluminum alloy (EN AW-6082) was first anodized to create an oxide layer on the surface of this component. A sulfuric acid electrolyte at a bath temperature of 5 °C and a current density of 4 A/dm ² was used for the anodization.

Subsequently, i.e. without intermediate drying, the component was exposed to a negative pressure in a vacuum cell in order to remove residues and impurities from the pores of the oxide layer. The component was then treated with an aqueous 10 wt. % sodium acrylate solution under vacuum. The vacuum is naturally selected so that the sodium acrylate solution does not boil. The sodium acrylate is present as an ionogenic dispersion in the aqueous solution. During treatment with the sodium acrylate solution, the component is polarized as an anode, with a direct voltage of 60 V and a current density of 2A/dm ² applied. The treatment time in this example was 5 minutes. The current density (directed flow) discharges/deposits/precipitates the acrylate (particles)/ions in the pore and thus closes the pores of the oxide layer produced by anodization.

The sodium acrylate solution was then removed and the component was heat treated at 100 to 180 °C. This causes the acrylate to polymerize, permanently sealing the pores.

In the exemplary process for producing the sealed surface, a film thickness of < 1 µm is formed on the surface. Depending on the duration and current strength, significantly thicker films can be achieved, ie up to 5 µm are achievable. Conversely, a very low film thickness can also be achieved, ie the polymerization of the acrylate takes place essentially within the pores The film thickness refers to an additional layer of sealant applied to the porous surface previously formed by anodizing.

List of reference symbols

20

Scrollpumpe

22

erstes Gehäuseelement

24

zweites Gehäuseelement/feststehendes Spiralbauteil

26

Spiralwand

28

Spiralwand

30

bewegliches Spiralbauteil

32

Exzenterwelle

34

Motor

36

Wälzlager

38

Exzenterzapfen

40

Wälzlager

42

Wellbalg

44

Lüfter

46

Luftleithaube

48

Elektronikgehäuse

50

Kanal

52

Kammer

54

Rippe

56

Ausnehmung

58

Rippe

60

Drucksensor

62

Kanal

64

Dichtungselement

66

Grundplatte

68

Haltevorsprung

70

erster Zwischenabschnitt

72

zweiter Zwischenabschnitt

74

dritter Zwischenabschnitt

76

Einspannvorrichtung

78

Dreibackenfutter

80

Ausnehmung

82

Ausgleichsgewicht

84

Befestigungsbohrung

86

Wellenabsatz

88

Gehäuseschulter

90

Gasballastventil

92

Betätigungsgriff

94

Kunststoffkörper

96

Basiselement

98

Bohrung

100

Rückschlagventil

102

Stopfen

104

Befestigungsschraube

106

drehbares Element

108

Bohrung

110

Bohrung

112

Deckel

114

Nut

116

innere Seitenwand

118

äußere Seitenwand

120

erster Spiralabschnitt

122

zweiter Spiralabschnitt

124

Luftstrom

126

Buchse

128

Stecker

130

Trennwand

132

Ausnehmung

134

Übergangspassung

136

O-Ring

138

Abdrückgewinde

140

Senkung

142

Befestigungsschraube

144

Dom

150

Dichtung

152

Gleitschicht

154

Träger

to the Fig. 1 to 16

20

Scroll pump

22

first housing element

24

second housing element/fixed spiral component

26

Spiral wall

28

Spiral wall

30

movable spiral component

32

Eccentric shaft

34

engine

36

roller bearing

38

Eccentric pin

40

roller bearing

42

Corrugated bellows

44

Fan

46

Air duct hood

48

Electronic housing

50

channel

52

chamber

54

rib

56

Recess

58

rib

60

Pressure sensor

62

channel

64

Sealing element

66

Base plate

68

Holding projection

70

first intermediate section

72

second intermediate section

74

third intermediate section

76

Clamping device

78

Three-jaw chuck

80

Recess

82

Counterweight

84

Mounting hole

86

Wave heel

88

Housing shoulder

90

Gas ballast valve

92

Operating handle

94

Plastic body

96

Basic element

98

drilling

100

check valve

102

Plug

104

Fixing screw

106

rotating element

108

drilling

110

drilling

112

Lid

114

Groove

116

inner side wall

118

outer side wall

120

first spiral section

122

second spiral section

124

Airflow

126

Rifle

128

Plug

130

partition wall

132

Recess

134

Transitional fit

136

O-ring

138

Forcing thread

140

Reduction

142

Fixing screw

144

Cathedral

150

poetry

152

Sliding layer

154

carrier

111

Turbomolekularpumpe

113

Einlassflansch

115

Pumpeneinlass

117

Pumpenauslass

119

Gehäuse

121

Unterteil

123

Elektronikgehäuse

125

Elektromotor

127

Zubehöranschluss

129

Datenschnittstelle

131

Stromversorgungsanschluss

133

Fluteinlass

135

Sperrgasanschluss

137

Motorraum

139

Kühlmittelanschluss

141

Unterseite

143

Schraube

145

Lagerdeckel

147

Befestigungsbohrung

148

Kühlmittelleitung

149

Rotor

151

Rotationsachse

153

Rotorwelle

155

Rotorscheibe

157

Statorscheibe

159

Abstandsring

161

Rotornabe

163

Holweck-Rotorhülse

165

Holweck-Rotorhülse

167

Holweck-Statorhülse

169

Holweck-Statorhülse

171

Holweck-Spalt

173

Holweck-Spalt

175

Holweck-Spalt

179

Verbindungskanal

181

Wälzlager

183

Permanentmagnetlager

185

Spritzmutter

187

Scheibe

189

Einsatz

191

rotorseitige Lagerhälfte

193

statorseitige Lagerhälfte

195

Ringmagnet

197

Ringmagnet

199

Lagerspalt

201

Trägerabschnitt

203

Trägerabschnitt

205

radiale Strebe

207

Deckelelement

209

Stützring

211

Befestigungsring

213

Tellerfeder

215

Not- bzw. Fanglager

217

Motorstator

219

Zwischenraum

221

Wandung

223

Labyrinthdichtung

to the Fig. 21 to 25 :

111

Turbomolecular pump

113

Inlet flange

115

Pump inlet

117

Pump outlet

119

Housing

121

Bottom part

123

Electronic 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

Rotation axis

153

Rotor shaft

155

Rotor disc

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

Connecting channel

181

roller bearing

183

Permanent magnet bearings

185

Injection nut

187

disc

189

Mission

191

rotor-side bearing half

193

stator side bearing half

195

Ring magnet

197

Ring magnet

199

Bearing gap

201

Carrier section

203

Carrier section

205

radial strut

207

Cover element

209

Support ring

211

Mounting ring

213

Disc spring

215

Emergency or rescue camp

217

Motor stator

219

Space

221

Wall

223

Labyrinth seal

Claims (15)

Pump, in particular vacuum pump, comprising a pump-active component with a coating, wherein the coating comprises a porous oxide layer, in particular formed by anodic oxidation in an acidic electrolyte, and a fluorine-free polymer-based and/or sol-gel-based seal, and wherein the pores of the oxide layer are at least partially covered by the sealant and/or impregnated with the sealant and/or filled with the sealant. Pump according to claim 1,
wherein it is a spiral or scroll pump, in particular a spiral or scroll vacuum pump, with conveying elements designed as spiral elements, wherein the seal is applied at least in regions to at least one of the conveying elements designed as spiral elements. Pump according to claim 1,
wherein it is a piston pump, in particular a piston vacuum pump, with at least one cylinder with an inner cylinder wall and a piston movable in the cylinder, wherein the seal is applied at least partially to the inner cylinder wall and/or the piston. Pump according to claim 1,
which is a turbomolecular pump, wherein the seal is applied at least partially to rotor disks and/or stator disks. Method for coating a pump-active component of a pump, comprising the following steps; Step A) Providing the pump-active component from a light metal workpiece with a porous oxide layer on a surface, Step B) Expose the pump-active component to a negative pressure, Step C) contacting the porous oxide layer with a solution comprising at least one, in particular fluorine-free, polymerizable sealing precursor and/or at least one sol-gel-based sealing precursor, wherein a voltage is applied to the pump-active part at least during one of steps A) to C). Method according to claim 5,
wherein in step C) the solution contains ions and/or ionic compounds. Method according to claim 5 or 6,
wherein the solution of step C) contains at least one compound having functional groups from the families of organic anions, such as substituted acrylates and/or substituted acetates and/or substituted styrenes and/or substituted isocyanates and/or carboxyls and/or sulfonic acid and/or from the family of inorganic ions, such as silicates, aluminates. Method according to at least one of claims 5 to 7,
whereby the voltage is gradually increased during the treatment of the pump-active component. Method according to at least one of claims 5 to 8,
where the voltage is between 50 and 300 V. Method according to at least one of claims 5 to 9,
wherein the voltage is applied to the pump-active component using a direct current. Method according to at least one of claims 5 to 10,
wherein the pump-active component is heat treated after completion of the electrochemical treatment, preferably at 100 °C to 300 °C. Method according to at least one of claims 5 to 11,
whereby the sealing precursor is precipitated in the pores during the electrochemical treatment. Method according to at least one of claims 5 to 12,
whereby the sealing precursor is polymerized in the pore. Pump with a pump-active component, obtainable by a process according to one of claims 5 to 13. Pump according to claim 14,
wherein the pump is a pump according to one of claims 1 to 4.

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