PUMP AND METHOD FOR PRODUCE A SEAL

Description

[0001] The present invention relates to a pump, in particular a vacuum pump, comprising, for example, at least two conveying elements movable relative to one another and at least one seal arranged on one of the two conveying elements. According to the invention, a seal is applied at least partially to, in particular, at least one of the conveying elements. Furthermore, the invention relates to the use of components provided with a seal and at least one seal for the production of pumps, in particular vacuum pumps, as well as to a method for producing a seal.

[0002] Fluids such as greases or oils 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 design, this gap is filled by a fluid, usually oil or grease, during pump operation, 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. Some coatings (paints, anodized layers, etc.) in particular have defects. A disadvantage of such pumps is that the media pumped by the pump, such as gases or vapors, can react with the fluids used as a seal, which can particularly reduce the sealing effect.Another problem, especially with vacuum pumps, is contamination of the recipient by the fluids used.

[0003] For this reason, so-called dry solutions are preferred, especially for vacuum pumps, where the pumped media does not come into contact with fluids. Sliding or sliding seals made of chemically resistant materials, usually plastics, are generally used here. In a piston pump, for example, such seals are usually arranged on the piston. During operation, the seal rubs against the inner wall of a cylinder in order to seal the resulting pumping chamber as hermetically as possible. Another example of a pump that is usually operated dry, i.e. without fluid lubricant, is a scroll or spiral pump. Scroll pumps have crescent-shaped pumping chambers formed by a rotor with a spiral cross-section in engagement with a similar spiral stator, with the rotor being set in an orbiting motion by an eccentric drive.To seal the conveying chambers, seals are provided on each of the spiral faces, with the rotor face seal rubbing against the stator and vice versa.

[0004] The disadvantage of such sliding or sliding seals is that they are generally subject to severe wear due to the constant sliding friction and often have a limited service life. In particular, after a certain period of operation, the seals can become abrasive in the form of dust in the pump chamber. With increasing wear, the sealing effect of the sliding seal decreases, which reduces the achievable ultimate pressure.

[0005] To reduce wear, sliding or protective coatings can be provided, as described, for example, in EP 3 153 706 A1. Such seals can comprise an oxide layer formed by anodic oxidation in an acidic electrolyte, particularly containing oxalic acid, sulfuric acid, or mixtures thereof. These seals / protective layers also increase the corrosion and wear resistance of the base material. GB 433 367 A discloses first forming an aluminum oxide layer on the surface of parts made of aluminum or aluminum alloys and then impregnating this oxide layer with a solution of a chlorinated rubber.

[0006] There are very narrow gaps (a few 0.01 mm) between the crescent-shaped scoops. In the event of contact between the two components forming the scoop or of solid particles penetrating the scoop, the hard sliding and protective layer ensures a longer service life of the base material. However, it has been found that, due to their porous structure, such oxide layers cannot achieve the required ultimate pressures and gas tightness, or only after a longer running time (the so-called running-in period). Although tests have shown that, particularly with newly coated components, a bake-out process can achieve reduced running-in periods or improved ultimate pressures, there is still room for improvement with regard to the achievable ultimate pressures and a reduction in running-in periods.

[0007] Increased corrosion resistance is required not only for piston pumps and scroll pumps, but also for turbomolecular pumps. Turbomolecular pumps are vacuum pumps that have a rotor rotating around a rotational axis of the rotor shaft. Pump-active components can be made of a light metal, particularly aluminum, which is coated with an oxide layer to increase corrosion resistance, similar to the above-mentioned sliding or protective layers, as described, for example, in EP 3 153 706 A1.

[0008] During operation, the pumping components come into contact with the pumped medium, which can have a corrosive effect on the pumping components. This can then lead to electrolytic corrosion, which begins at the pores of components covered with a porous oxide layer.

[0009] It is therefore an object of the present invention to provide pumps with improved corrosion protection.

[0010] This object is achieved by a pump and by a method according to the independent claims.

[0011] 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 sealant, 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.

[0012] It has been found that in a pump according to the invention, the active pumping component is protected from corrosion due to the seal. In particular, electrolytic corrosion, which typically begins at the pores, is effectively prevented by the seal according to the invention. Due to the seal, this corrosion protection is available for various pump types, such as scroll pumps, turbomolecular pumps, or piston pumps.

[0013] The seal also performs other tasks. In scroll and piston pumps, the seal also acts as a sliding layer, thus fulfilling two functions: 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.

[0014] The oxide layer is preferably formed by anodic oxidation, particularly in an acidic electrolyte. The electrolyte preferably comprises 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 exhibit the aforementioned multifunctional properties with regard to lubrication and protection, provided the sealant, as described herein, is applied thereto.

[0015] 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 ultimate pressures than sliding layers as described, for example, in EP 3 153 706 A1 or 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 arranged horizontally to the layer, which connect the vertical pores to one another. In addition to the pores, such hard oxide layers have further defects, e.g. in the form of inclusions and cracks. Defects and pores represent microscopic channels through which gases can flow. Furthermore, substances, e.g. water, can outgas from these locations.This reduces the gas tightness, which has an undesirable effect on the achievable ultimate pressures. This means that, particularly with scroll pumps, the required ultimate pressures and gas tightness cannot be achieved or can only be achieved after a longer 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, outgassing of the enclosed media, e.g. coating residues, takes place. It has been found that the sealing allows the required ultimate pressures to be reached even faster, while at the same time maintaining a high level of wear protection. 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 sealing and a gas flow within the sealed layer, e.g.of the sliding layer, or outgassing therefrom is prevented or at least reduced. Compared with the seals or sliding layers from the aforementioned prior art, it is assumed that in the pump according to the invention, the pores of the oxide layer are at least partially filled with the sol-gel-based sealing material or with a fluorine-free polymer. This also seals cross-connections between vertical pores, i.e., the branches arranged horizontally to the layer. This achieves an even shorter running-in time than with the known sliding layers.

[0016] In contrast to the prior art, as described in EP 3 153 706 A1 or EP 3 940 234 A2, the polymer-based sealant is fluorine-free. "Fluorine-free" refers here to materials that contain essentially no fluorine. This means that although fluorine-containing compounds may be present in the form of impurities or other additives, they do not significantly alter the fundamental properties of the sealant, i.e., the improvement in corrosion protection. Preferably, "fluorine-free" refers here 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.

[0017] The present invention further 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 a voltage is applied to the pump-active part at least during one of steps A) to C).

[0018] The process according to the invention seals the porous oxide structure on the surface of a pump-active component, thereby protecting it from corrosion. Since the process according to the invention uses negative pressure, inclusions are removed from the pores of the oxide structure. This allows the sealing precursor to penetrate better and deeper into the pores. It also removes moisture from the oxide layer, further reducing wear on the sealed oxide layer.

[0019] The light metal workpiece is in particular an aluminum workpiece, e.g. made of one of the aluminum alloys mentioned herein.

[0020] By applying a voltage, the sealing precursors are transported into the pores of the oxide layer, achieving very deep penetration of the pores with the sealant. It is assumed that this penetration allows both horizontal pores and vertical branches to be sealed by the process according to the invention. The achievable final pressures and the required run-in times are therefore very low.

[0021] The present invention further relates to a pump having a pump-active component which is obtainable by the method according to the invention.

[0022] 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. Particularly preferably, the sealed oxide layer is provided at least on one tip seal. In this case, the seal is applied at least in some areas to at least one of the conveying elements designed as spiral elements. In spiral or scroll pumps, the present invention solves additional problems, such as shortening the run-in time while simultaneously achieving low achievable final pressures.

[0023] 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 movable within the cylinder. In this embodiment of the invention, the seal is applied at least partially 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. This shortens the tightness and running-in times.

[0024] According to a further preferred embodiment, the pump according to the invention is a turbomolecular pump, wherein the seal is applied at least partially to rotor disks and / or stator disks. With 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 occur. The improvement in corrosion resistance therefore improves the longevity of the turbomolecular pump according to this preferred embodiment of the invention.

[0025] The pump-active component is preferably formed from a lightweight metal material. The lightweight metal material is preferably an aluminum alloy, although the present invention is not limited thereto. Aluminum alloys of the 4000 series, 5000 series, and 6000 series have proven particularly suitable, with the aluminum alloys of the 6000 series being particularly preferred. Examples of aluminum alloys of the 6000 series are AlMgSi1 (EN AW-6082) and AlMgSi0.5 (EN AW-6060).

[0026] The surface of the pump-active component has an oxide layer. This oxide layer can be formed in various ways. Known methods for this include, for example, anodizing. 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.

[0027] In the pump according to the invention, the sealing layer thickness is preferably less than or equal to 5 µm, more preferably less than or equal to 3 µm, and even more preferably less than or equal to 1 µm. The sealing layer thickness can be influenced in the manufacturing 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 treatment of the pump-active component. This layer thickness can be determined, for example, using electron micrographs.

[0028] In the process 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 process according to the invention, these ions or ionic compounds can penetrate deep into the pores of the oxide layer, where they then provide the seal. Due to the deep penetration into the pores, even deep horizontal branches of the porous oxide layer are sealed.

[0029] 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 and 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 electrical voltage, thus enabling deep sealing. 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.

[0030] 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%.

[0031] The solution of step C) is preferably an aqueous solution, in particular an aqueous acrylate salt solution in the form of an ionogenic dispersion.

[0032] 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.

[0033] 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< , even 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< .

[0034] In the method according to the invention, it has proven advantageous to apply the voltage to the pump-active component using a direct current. This transports precursors of the sealant deep into the pores of the oxide layer to form the sealant there. Within the pores, the precursor compounds, e.g., an acrylate salt and / or a derivative thereof, are deposited or precipitated, so that the sealant forms within the pores. This leads to deep impregnation, which also seals horizontal branches of the porous structure.

[0035] 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 of 80°C to 300°C, in particular in the range of 100 to 230°C. During the heat treatment, the sealant forms from the precursors of the sealant. Furthermore, the heat treatment can reduce moisture in the porous layer of the pump-active component, which has a beneficial effect on tribological wear.

[0036] In a preferred variant of the present inventive method, the sealing precursor is precipitated in the pores during the electrochemical treatment. Particularly in sol-gel-based seals, the sealing precursors, i.e., a sol, first penetrate into the pores of the oxide layer. Precipitation then occurs simultaneously with the formation of the gel, i.e., the seal. Since the sol can penetrate very deeply into the pores, the sealing also occurs deep within the pores. This at least partially fills the pores and, in particular, seals horizontal branches.

[0037] 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 prepolymer and can penetrate deep into the pores of the oxide layer in the form of a solution or dispersion. Polymerization increases the size of the monomers or prepolymers, so that they seal within the pores and remain in the pores. Polymerization can also change the solubility of the monomers or prepolymers, so that they precipitate in the pores and cause deep sealing, even of horizontal branches in the porous structure of the oxide layer.

[0038] 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 production of the porous oxide layer. In principle, the production of the porous oxide layer can also already take place under negative pressure. Preferably, the pump-active component is exposed to the further process without further drying after the production of the oxide layer. If drying takes place after the production of the oxide layer, e.g., by anodizing, the pores can be closed by natural oxidation, which impairs the quality of the seal. Therefore, preferably, after the production of the oxide layer on the surface of the pump-active component, the further process is 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 generation of the oxide layer, e.g. by anodizing, and the further process.

[0039] The method according to the invention is preferably part of the manufacture of a pump, in particular a vacuum pump, as described herein.

[0040] According to a preferred variant of the present invention, the pump according to the invention with a pump-active component, which is obtainable by the method described herein, is a pump with all the details which are also described herein independently of the method according to the invention for pumps.

[0041] 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 electronics housing of the scroll pump. Fig. 3 shows the scroll pump in a perspective view, with selected elements cut out. 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, Fig. 5 visible side opposite side. Fig. 7 shows a clamping device for a spiral component. Figs. 8 and 9 each show an eccentric shaft with a counterweight of 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 portion of the spiral component of the Figs. 5 and 6 . Fig. 13 shows a cross-section of the spiral component through the spiral wall in an outer end area. Fig. 14 shows an air guide hood of the scroll pump of the Fig. 1in perspective view. Fig. 15 shows a sectional view of a forcing thread. 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 more magnified electron microscopic cross-sectional view of the oxide layer of Fig. 16 . Fig. 19 shows an electron microscopic view of the oxide layer of Figs. 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 underside 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. 22shown section line BB. Fig. 25 shows a cross-sectional view of the turbomolecular pump along the Fig. 22 shown section line CC.

[0042] 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).

[0043] The Fig. 1shows a vacuum pump designed as a scroll pump 20. This comprises a first housing element 22 and a second housing element 24, wherein the second housing element 24 has a pumping-active structure, namely a spiral wall 26. The second housing element 24 thus forms a stationary spiral component of the scroll pump 20. The spiral wall 26 interacts with a spiral wall 28 of a movable spiral component 30, wherein the movable spiral component 30 is 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.

[0044] 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 rotational axis, which transmits its eccentric deflection to the movable spiral component 30 via a further roller bearing 40. For sealing purposes, 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.

[0045] The scroll pump 20 includes 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 such that the cooling air flow essentially surrounds the entire pump housing, thus achieving good cooling performance.

[0046] 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.

[0047] The electronics housing 48 is in Fig. 2illustrated in more detail. It comprises a plurality of 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 such that different variants of the electronic components, in particular different assembly variants of a circuit board, can be arranged and / or encapsulated in the electronics housing 48. For certain variants, individual chambers 52 can also remain empty, i.e. have no electronic component. In this way, a so-called modular system for different pump types can be implemented in a simple manner.The potting material can in particular be thermally conductive and / or electrically insulating.

[0048] At a related Fig. 2 Formed on the rear side of the electronics housing 48 are a plurality of walls or ribs 54, which define a plurality of channels 50 for conducting a cooling air flow. The chambers 52 also enable particularly good heat dissipation from the electronic components arranged therein, particularly in conjunction with a thermally conductive encapsulation material, and toward the ribs 54. The electronic components can thus be cooled particularly effectively, and their service life is improved.

[0049] In Fig. 3the scroll pump 20 is shown in perspective as a whole, but with the air guide hood 46 hidden so that in particular the fixed spiral component 24 and the fan 44 are visible. A plurality of recesses 56 arranged in a star shape are provided on the fixed spiral component 24, 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 the first housing element 22 or the electronics housing 48. This arrangement is particularly advantageous because the pumping-active region of the pump 20 develops a high level of heat due to the compression during operation and is therefore primarily cooled here.

[0050] The pump 20 includes an integrated pressure sensor 60. This is arranged within the air guide hood 46 and screwed into the fixed spiral component 24. The pressure sensor 60 is connected via a cable connection (only partially shown) to the electronics housing 48 and a control device arranged therein. The pressure sensor 60 is integrated into the control system of the scroll pump 20. For example, the motor 34, which is Fig. 1 visible, depending on a pressure measured by pressure sensor 60. For example, when using 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 pressure sensor 60 measures a sufficiently low pressure. This protects the high-vacuum pump from damage.

[0051] Fig. 4shows the pressure sensor 60 and its arrangement on the stationary 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-active outer region between the spiral walls 26 and 28 of the stationary and movable spiral components 24 and 30, respectively. Thus, the pressure sensor measures a suction pressure of the pump. Alternatively or additionally, a pressure between the spiral walls 26 and 28 in a pumping-active region 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.

[0052] The pressure sensor 60 allows, for example by determining compression, in particular the detection of a wear condition of the pump-active components, in particular of a sealing element 64 also referred to as a tip seal. Furthermore, the measured suction pressure can also be used to control the pump (including the pump speed). For example, a suction pressure can be specified via software and a suction 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 for by increasing the speed. In this way, 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.

[0053] The pressure sensor 60 can be provided optionally, for example. Instead of the pressure sensor 60, a blind plug can be provided to close the channel 62. A pressure sensor 60 can then be retrofitted, for example, if necessary. 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.

[0054] The pressure sensor 60 is arranged in the cooling air stream of the fan 44. This also advantageously cools it. This also means that no special measures are required to increase the temperature resistance of the pressure sensor 60, allowing a more cost-effective sensor to be used.

[0055] In addition, the pressure sensor 60 is arranged in particular such that the external dimensions of the pump 20 are not increased by it and the pump 20 consequently remains compact.

[0056] In the Figs. 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 includes a base plate 66 from which the spiral wall 28 extends.

[0057] 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, among other things, several mounting recesses, for example for mounting the bearing 40 and the bellows 42, which are Fig. 1 are visible.

[0058] On the outside of the base plate 66, three retaining projections 68 are provided, spaced apart and evenly distributed over the circumference of the base plate 66. The retaining projections 68 extend radially outward. In particular, the retaining projections 68 all have the same radial height.

[0059] A first intermediate section 70 of the circumference of the base plate 66 extends between two of the retaining projections 68. This first intermediate section 70 has a greater radial height than a second intermediate section 72 and a third intermediate section 74. The first intermediate section 70 is arranged opposite an outermost 120° section of the spiral wall 28.

[0060] During the manufacture of the movable spiral component 30, the base plate 66 and the spiral wall 28 are preferably manufactured jointly from a solid material, ie the spiral wall 28 and the base plate 66 are formed in one piece.

[0061] For example, during finishing operations, 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 The side of the base plate 66 shown is machined, in particular the fastening recesses are created. In principle, the spiral wall 28 can also be machined from solid material within the scope of this clamping.

[0062] 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 engagement 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. 6shown side thereof. Thus, machining operations can be carried out from both sides during clamping, in particular at least a finishing operation of the spiral wall 28 and the introduction of fastening recesses.

[0063] The contour of the retaining projections 68 and the clamping pressure of the clamping device 76 are preferably selected such that no critical deformations of the spiral component 30 occur. The three retaining projections 68 are preferably selected such that the outer dimension, i.e., the maximum diameter of the spiral component 30, is not increased. This allows for savings in material and machining volume. 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 different from the number of retaining projections 68 on the movable spiral component 30.

[0064] On the eccentric shaft 32 of the Fig. 1 Two balancing weights 82 are mounted to compensate for any imbalance in the excited system. The area of ​​the Fig. 1 right-hand balance weight 82 is in Fig. 8Enlarged image. The counterweight 82 is screwed to the eccentric shaft 32.

[0065] A similar image section is in Fig. 9 shown for another scroll pump, which preferably belongs to 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.

[0066] The eccentric shafts 32, the counterweights 82 and the housing elements 22 are dimensioned such that only one specific type of the two types of counterweights 82 shown can be mounted on the eccentric shaft 32 at the respective mounting position shown.

[0067] The balancing weights 82 are in the Figs. 8 and 9 together with certain dimensions of the installation space provided for them, to clarify that the counterweight 82 of the Fig. 9cannot be mounted on the eccentric shaft 32 and vice versa. It is understood that the dimensions given are purely exemplary.

[0068] In Fig. 8 a distance between a mounting hole 84 and a shaft shoulder 86 9.7 mm. The counterweight 82 of the Fig. 8 is shorter in the corresponding direction, namely 9 mm long, so it can be installed without any problems. The counterweight 82 of the Fig. 9 has a longitudinal extension of 11 mm measured from the mounting hole. Thus, the counterweight 82 of the Fig. 9 not on the eccentric shaft 32 of the Fig. 8 cannot be mounted, since the shaft shoulder 86 collides with the counterweight 82 during an attempted mounting or since the counterweight 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. 9in both dimensions is greater than the distance between the fastening hole 84 and the shaft shoulder 86 in Fig. 8 , also prevents installation in the reverse direction. In addition, the dimension of 21.3 mm of the counterweight 82 of the Fig. 8 an inverted and consequently incorrect mounting orientation of the otherwise correct counterweight 82.

[0069] 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, the Fig. 9 collide with the housing shoulder 88, so that complete assembly would not be possible. Incorrect assembly is possible at first, but is reliably detected. If the counterweight 82 of the Fig. 8 on the eccentric shaft 32 of the Fig. 9the 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 bore 84.

[0070] The counterweights 82, in particular a motor-side counterweight 82, are generally designed to prevent confusion of the counterweight with those of other sizes during assembly and / or servicing. The counterweights are preferably attached using through-bolts. Similar counterweights of different pump sizes are particularly designed to prevent installation of the wrong counterweight due to adjacent shoulders on the shaft, the positions of the thread and through-hole of the counterweight, and shoulders within the housing.

[0071] 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. 3visible and arranged on the fixed spiral component 24.

[0072] 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-bore 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 bore 98 is also closed in the illustrations by a plug 102. Instead of the plug 102, a filter, for example, can also be provided, wherein the ballast gas can preferably be air and enters the valve 90 directly via the filter.

[0073] The operating handle 92 is fastened 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, Fig. 11only one is visible. The rotatable element 106 is rotatably attached to the second housing element 24 by a fastening screw (not shown) extending through a bore 110.

[0074] To actuate the valve 90, a torque applied manually to the actuating handle 92 is transmitted to the rotatable element 106, thus rotating it. Thus, the bore 98 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.

[0075] Bores 108 and 110 are closed by a cover 112. The sealing effect of the gas ballast valve 90 is based on axially compressed O-rings. When the valve 90 is actuated, a relative movement is exerted on the O-rings. If contaminants, such as particles, reach 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.

[0076] This cover 112 is secured via an interference fit of three centering elements. Specifically, the cover 112 has a plug-in pin (not shown) for each bore 108, which secures the cover 112 in the bores 108. The bores 108 and 110, as well as the fastening screws arranged therein, are thus protected from contamination. In particular, the ingress of contamination into the valve mechanism can be effectively minimized for the fastening screw (not shown) arranged in the bore 110, which allows rotational movement, thus improving the service life of the valve.

[0077] The plastic handle with an overmolded stainless steel base ensures good corrosion resistance while keeping manufacturing costs low. Furthermore, the plastic handle stays cooler due to limited heat conduction, making it easier to use.

[0078] For the fan 44, as used for example in the Fig. 1 and 3 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, for example, in the electronics housing 48. The speed is set in line with the power consumption. However, control is only permitted above a module temperature of 50 °C. If the pump enters temperature ranges of possible derating (temperature-related power reduction), the max. fan speed is automatically controlled. This control ensures that a minimum noise level is achieved when the pump is cold, that a low noise level - corresponding to the pump noise - prevails at ultimate pressure or at low load, that optimal cooling of the pump is achieved with a low noise level at the same time, and that the maximum cooling capacity is ensured before a temperature-related power reduction.

[0079] The maximum fan speed can be adjusted, especially depending on the situation. For example, it may be beneficial to reduce the maximum fan speed to ensure high water vapor tolerance.

[0080] 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.

[0081] The spiral wall 28 has, at its end facing away from the base plate 66 and towards a base plate of the fixed spiral component 24 (not shown here), a groove 114 for the insertion of 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. 4clearly 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.

[0082] The groove 114 is delimited outwardly and inwardly by two opposite side walls, namely 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.

[0083] 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°.

[0084] 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-active region of the spiral wall 28. In particular, the first spiral section 120 can at least substantially completely fill the non-pumping-active region of the spiral wall 28.

[0085] As it is in Fig. 5 As can be seen, the first intermediate section 70, which has a greater radial height than other intermediate sections 72 and 74, can preferably be arranged opposite the first spiral section 120 between two retaining projections 68. An imbalance introduced by the thicker side wall 118 can thus be compensated for by the greater weight of the first intermediate section 70.

[0086] To keep the system load on the bearings and other components low, the moving scroll component should generally have a low dead weight. For this reason, the scroll walls are 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 scroll wall thickness is, for example, a maximum of 0.17. However, due to the tip seal groove, the scroll wall tip is very sensitive to impacts during handling, such as during assembly or when changing the tip seal. Slight impacts, e.g. during transport, can push the side wall of the groove inwards, making it impossible to install the tip seal. To solve this problem, the groove has an asymmetrical wall thickness, in particular a local thickening of the scroll 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 coil, especially the last half, significantly reduces damage. At other parts of the component, thickening of the spiral wall is preferably not necessary, as the wall is protected by protruding elements of the component.

[0087] 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) that 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 shown, for example, in the Fig. 2 and3 visible. Connector 128 is connected to fan 44 via a cable not shown.

[0088] The plug connection 126, 128 is separated from the air flow 124 by a partition 130. The air flow 124, which may contain, for example, dust or similar contaminants, is thus kept away from the plug connection 126, 128. This protects the plug connection 126, 128 itself, while preventing contaminants from entering the electronics housing 48 through the opening provided for the socket 126 and reaching the control device and / or power electronics.

[0089] The air guide hood 46 is in Fig. 14shown separately and in perspective. Visible, among other things, is the partition 130 with the space defined behind it for the connector 128. The partition 130 includes a recess 132, designed here as a V-shaped notch, for passing a cable from the connector 128 to the fan 44.

[0090] For example, to save costs, inexpensive connectors without sealing (e.g., no IP protection) can be used, since the partition 130 ensures that the sucked-in air does not reach the electronics via the opening in the connector 126, 128. The fan cable is guided laterally through the partition 130 through the V-shaped notch 132. The notch 132 is laterally offset from the connector 126, 128, creating a labyrinth effect and thus further reducing 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. This creates less turbulence and backpressure for the fan 44.

[0091] The Fig. 15shows a contact area between the first housing element 22 and the second housing element or stationary 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. Sealing is provided by 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.

[0092] For maintenance purposes, for example to replace the sealing element 64, the second housing element 24 must be disassembled. In doing so, the transition fit 134 or the O-ring 136 may jam 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 it in further, the housing elements 22 and 24 are pressed away from one another.

[0093] 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 they are shown, for example, in the Fig. 1 and 3 For this purpose, the forcing thread 138 preferably has the same thread type as the fastening threads provided for the fastening screws 142.

[0094] 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 screwing the screw into the forcing thread 138, they collect in the countersink 140. This prevents such abrasion particles from, for example, preventing the housing elements 22 and 24 from fully engaging one another.

[0095] When assembling the fixed spiral component 24, the screws must be removed again, as otherwise a complete screwing (correct fit on the flat surface of the housing) of the fixed spiral component 24 to the first housing element 22 may be prevented. Leakage, misalignment and a reduction in pump performance may result. To avoid this assembly error, the air guide hood 46 has at least one, in particular additional, Fig. 14The dome 144 shown here only allows the air guide hood 46 to be mounted if the screws used for forcing, in particular the fastening screws 142, have been removed. This is because the air guide hood 46 with the dome 144 is designed in such a way that it would collide with the screw head of any forcing screw screwed into the forcing thread 138, so that the air guide hood 46 would not be fully mountable. In particular, the air guide hood 46 can only be mounted if the forcing screws are completely removed.

[0096] Fig. 16shows 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 spiral elements 26, 28 are arranged 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 buildup does not necessarily take place.The preferably fluorine-free seal 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, thereby improving the achievable final pressures and shortening the running-in time.

[0097] 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. Fig. 6 For example, the seal 150 (Tip Seals) shown is an acrylate-based fluorine-free polymer.

[0098] The pump according to the invention can comprise one or more of the features described above with reference to Figures 1 to 16 described features, wherein any combination of these features can be realized in a pump according to the invention.

[0099] 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. 19which shows an electron microscopic view of the oxide layer of Fig. 17 and Fig. 18 where the pores 160 appear as dark, vertical stripes, and very small defects 158 are visible 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 ramifications, can be seen. In Figures 17 to 19, only a few pores and defects are marked with reference symbols.

[0100] The effect of the sliding layer of the pump according to the invention is shown in Fig. 20This can be seen in the graph shown. The time in hours is plotted on the abscissa (x-axis), and the pressure in hPa is plotted on the ordinate. Under identical conditions, a negative pressure was generated using scroll vacuum pumps, and the development of the negative pressure was recorded over time.

[0101] In all lines A to D, a HiScroll type pump was used, the only difference being that in line A the conveying elements have no coating. In line B, the conveying elements have a coating as described in EP 3 153 706 A1, wherein a sulfuric acid electrolyte was used to produce the oxide layer, i.e. 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 described in EP 3 940 234 A2. 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 in line D was produced as described in the following example.

[0102] As can be seen from line A, although a low ultimate pressure can be achieved very quickly with uncoated pumping elements, this pressure is unstable due to wear on the pumping elements. A stable, yet relatively high ultimate pressure, even after a long run-in phase, can be achieved with an anodic coating on the pumping elements. This is clearly evident in line B. For the pump in line B, the test was interrupted after a short run-in period, and a seal was applied to the oxide layer. Upon resuming the test, it is noticeable that the pressure drops much more quickly and a significantly lower ultimate pressure is reached.Line C shows that although a lower ultimate pressure can be achieved with the fluorine-containing seal known from the prior art, a certain running-in phase is still necessary and there is the disadvantage of using fluorine-containing components which, due to their persistence 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 significantly lower ultimate pressure than in line B (until the test is interrupted), whereby the vacuum achieved is stable, unlike in line A. For lines B and C, a significantly longer running-in time is to be expected until the lower ultimate pressures are reached. With the sealing according to the invention, not only is an excellent achievable ultimate pressure achieved, but the running-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 running-in times, low final pressures and high corrosion and wear resistance.

[0103] However, the pump according to the invention can also be a turbomolecular pump as described in the Fig. 21 to 25 is generally described.

[0104] 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.

[0105] The inlet flange 113 forms the vacuum pump alignment according to Fig. 21the 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 housed in the electronics housing 123, e.g., for operating an electric motor 125 arranged in the vacuum pump (see also Fig. 23 ). Several connectors 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 connector 131 are arranged on the electronics housing 123.

[0106] There are also turbomolecular pumps that do not have such an attached electronics housing, but are connected to external drive electronics.

[0107] On the housing 119 of the turbomolecular pump 111, a flooding inlet 133, in particular in the form of a flooding valve, is provided, 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 is supplied to protect the electric motor 125 (see e.g. Fig. 23 ) can be admitted 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. Furthermore, two coolant connections 139 are arranged in the lower part 121, one of which serves as an inlet and the other as an outlet for coolant, which can be fed into the vacuum pump for cooling purposes. Other existing turbomolecular vacuum pumps (not shown) are operated exclusively with air cooling.

[0108] 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. However, the vacuum pump 111 can also be attached to a recipient via the inlet flange 113 and thus operated in a suspended position. Furthermore, the vacuum pump 111 can be designed so that it can also be operated when oriented in a different manner than in Fig. 21 As shown. Embodiments of the vacuum pump can also be realized in which the underside 141 is arranged facing either sideways or upwards, rather than downwards. In principle, any angle is possible.

[0109] Other existing turbomolecular vacuum pumps (not shown), which are particularly larger than the pump shown here, cannot be operated in an upright position.

[0110] On the underside 141, which is in Fig. 22As shown, various screws 143 are arranged, by means of which components of the vacuum pump (not further specified here) are fastened together. For example, a bearing cover 145 is attached to the underside 141.

[0111] Mounting holes 147 are also arranged on the underside 141, through which the pump 111 can be attached, for example, to a support surface. This is not possible with other existing turbomolecular vacuum pumps (not shown), which are particularly larger than the pump shown here.

[0112] 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.

[0113] 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.

[0114] A rotor 149 is arranged in the housing 119 and has a rotor shaft 153 rotatable about a rotation axis 151.

[0115] The turbomolecular pump 111 comprises several turbomolecular pump stages connected in series for pumping purposes, with several radial rotor disks 155 attached to the rotor shaft 153 and stator disks 157 arranged between the rotor disks 155 and secured 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.

[0116] The vacuum pump also includes Holweck pump stages arranged radially one inside the other and connected in series for pumping efficiency. Other turbomolecular vacuum pumps (not shown) exist that do not have Holweck pump stages.

[0117] The rotor of the Holweck pump stages comprises a rotor hub 161 arranged on the rotor shaft 153 and two cylindrical-shell-shaped Holweck rotor sleeves 163, 165 attached to and supported by the rotor hub 161, which are oriented coaxially to the rotational axis 151 and nested within one another in the radial direction. Furthermore, two cylindrical-shell-shaped Holweck stator sleeves 167, 169 are provided, which are also oriented coaxially to the rotational axis 151 and nested within one another in the radial direction.

[0118] The pumping surfaces of the Holweck pump stages are formed by the lateral 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 together with the latter forms the first Holweck pump 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 together with the latter forms a second Holweck pump 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 together forming the third Holweck pumping stage.

[0119] At the lower end of the Holweck rotor sleeve 163, a radially extending channel can be provided, via which the radially outer Holweck gap 171 is connected to the central Holweck gap 173. Furthermore, at the upper end of the inner Holweck stator sleeve 169, a radially extending channel can be provided, via which the central Holweck gap 173 is connected to the radially inner Holweck gap 175. This connects the nested Holweck pump stages in series. A connecting channel 179 to the outlet 117 can also be provided at the lower end of the radially inner Holweck rotor sleeve 165.

[0120] The above-mentioned pump-active surfaces of the Holweck stator sleeves 167, 169 each have a plurality of Holweck grooves extending 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.

[0121] 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.

[0122] In the area of ​​the rolling bearing 181, a conical spray nut 185 with an outer diameter increasing toward the rolling bearing 181 is provided on the rotor shaft 153. The spray nut 185 is in sliding contact with at least one wiper 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.

[0123] The operating fluid storage comprises several stacked absorbent discs 187, which are impregnated with an operating fluid for the rolling bearing 181, e.g. with a lubricant.

[0124] During operation of the vacuum pump 111, the operating fluid is transferred by capillary action from the operating fluid reservoir via the wiper to the rotating injection nut 185. As a result of centrifugal force, it is conveyed along the injection nut 185 in the direction of the increasing outer diameter of the injection nut 185 to the rolling bearing 181, where it fulfills a lubricating function, for example. The rolling bearing 181 and the operating fluid reservoir are enclosed in the vacuum pump by a trough-shaped insert 189 and the bearing cover 145.

[0125] The permanent magnet bearing 183 comprises a rotor-side bearing half 191 and a stator-side bearing half 193, each comprising a ring stack of several permanent magnet rings 195, 197 stacked one on top of the other in the axial direction. The ring magnets 195, 197 are arranged opposite one another, forming a radial bearing gap 199, with the rotor-side ring magnets 195 being arranged radially outward and the stator-side ring magnets 197 being arranged radially inward.

[0126] The magnetic field present in the bearing gap 199 creates magnetic repulsion forces between the ring magnets 195, 197, which effect 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 radially surrounds the ring magnets 195 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 support section 203 and a fastening ring 211 connected to the support section 203.A disc spring 213 may also be provided between the fastening ring 211 and the ring magnets 197.

[0127] Within the magnetic bearing, an emergency or backup bearing 215 is provided, which runs idle without contact during normal operation of the vacuum pump 111 and only engages upon excessive radial deflection of the rotor 149 relative to the stator, forming a radial stop for the rotor 149 to prevent collision of the rotor-side structures with the stator-side structures. The backup bearing 215 is designed as an unlubricated rolling bearing and forms a radial gap with the rotor 149 and / or the stator, causing the backup bearing 215 to be disengaged during normal pumping operation. The radial deflection at which the backup bearing 215 engages is large enough so that the backup bearing 215 does not engage during normal operation of the vacuum pump, yet small enough so that collision of the rotor-side structures with the stator-side structures is prevented under all circumstances.

[0128] 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 portion of the rotor shaft 153 extending through the motor stator 217. Between the motor stator 217 and the portion of the rotor 149 extending through the motor stator 217, an intermediate space 219 is arranged, 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.

[0129] The motor stator 217 is secured in the housing within the motor compartment 137 provided for the electric motor 125. A seal gas, also referred to as purge gas, which may be air or nitrogen, for example, can enter the motor compartment 137 via the seal gas connection 135. The seal gas can be used to protect the electric motor 125 from process gas, e.g., from corrosive components of the process 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 equal to the vacuum pressure created by the backing pump connected to the pump outlet 117.

[0130] 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.

[0131] The sealing of a porous oxide layer is described below as an example. It is understood that the following description serves only as an illustration and does not limit the invention in any way.

[0132] 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. A sulfuric acid electrolyte was used for the anodization at a bath temperature of 5 °C and a current density of 4 A / dm².

[0133] Subsequently, i.e. without intermediate drying, the component was subjected to 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 applied vacuum. The vacuum was naturally selected such that the sodium acrylate solution did 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 poled as an anode, with a direct voltage of 60 V and a current density of 2 A / dm2< 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.

[0134] The sodium acrylate solution was then removed, and the component was heat-treated at 100 to 180 °C. This polymerizes the acrylate, permanently sealing the pores.

[0135] In the exemplary process for producing the sealed surface, a film thickness of < 1 µm forms on the surface. Depending on the duration and current intensity, significantly thicker films can be achieved, i.e., up to 5 µm. Conversely, a very thin film thickness can also be achieved, i.e., the polymerization of the acrylate takes place primarily within the pores. The film thickness refers to an additional layer applied by the sealant to the porous surface previously formed by anodizing. List of reference symbols

[0136] to the Fig. 1 to 1620Scroll pump 22First housing element 24Second housing element / stationary scroll component 26Scroll wall 28Scroll wall 30Movable scroll component 32Eccentric shaft 34Motor 36Rolling bearing 38Eccentric pin 40Rolling bearing 42Bellows 44Fan 46Air guide hood 48Electronics housing 50Channel 52Channel 54Rib 56Recess 58Rib 60Pressure sensor 62Channel 64Seal element 66Base plate 68Retaining projection 70First intermediate section 72Second intermediate section 74Third intermediate section 76Clamping device 78Three-jaw chuck 80Recess 82Counterweight 84Mounting hole 86Shaft shoulder 88Housing shoulder 90Gas ballast valve 92Operating handle 94Plastic body 96Base element 98Bore 100Check valve 102Plug 104Fastening screw 106Rotatable element 108Bore 110Bore 112Cover 114Groove 116Inner side wall 118Outer side wall 120First spiral section 122Second spiral section 124Air flow 126Socket 128Plug 130Partition 132Recess 134Transition fit 136O-ring 138Forcing thread140Countersink 142Fastening screw 144Dom 150Seal 152Sliding layer 154Support to the Fig. 21 to 25: 111Turbomolecular pump 113Inlet flange 115Pump inlet 117Pump outlet 119Housing 121Lower section 123Electronics housing 125Electric motor 127Accessory connection 129Data interface 131Power supply connection 133Flood inlet 135Seal gas connection 137Motor compartment 139Coolant connection 141Underside 143Screw 145Bearing cover 147Mounting hole 148Coolant line 149Rotor 151Rotation axis 153Rotor shaft 155Rotor disc 157Stator disc 159Spacer ring 161Rotor hub 163Holweck rotor sleeve 165Holweck rotor sleeve 167Holweck stator sleeve 169Holweck stator sleeve 171Holweck gap 173Holweck gap 175Holweck gap 179Connecting channel 181Rolling bearing 183Permanent magnet bearing 185Injection nut 187Disc 189Insert 191Rotor-side bearing half 193Stator-side bearing half 195Ring magnet 197Ring magnet 199Bearing gap 201Support section 203Support section 205Radial strut 207Cover element 209Support ring 211Fastening ring 213Disc spring 215Emergency orFanglager 217Motorstator 219Zwischenraum 221Wandung 223Labyrinthdichtung.

Claims

1. A pump, in particular a vacuum pump, comprising a pump-active component having a coating, wherein the coating comprises an oxide layer having pores, which oxide layer is in particular formed by anodic oxidation in an acidic electrolyte, and a fluorine-free polymer-based and / or sol-gel-based sealing, and wherein the pores of the oxide layer are at least partly covered by the sealing and / or impregnated with the sealing and / or filled with the sealing.

2. A pump according to claim 1, wherein it is a spiral pump or scroll pump (20), in particular a spiral vacuum pump or scroll vacuum pump (20), comprising conveying elements formed as spiral elements (26, 28), wherein the sealing is at least regionally applied to at least one of the conveying elements formed as spiral elements (26, 28).

3. A pump according to claim 1, wherein it is a piston pump, in particular a piston vacuum pump, comprising at least one cylinder, which has an inner cylinder wall, and a piston movable in the cylinder, wherein the sealing is at least regionally applied to the inner cylinder wall and / or the piston.

4. A pump according to claim 1, wherein it is a turbomolecular pump (111), wherein the sealing is at least regionally applied to rotor disks (155) and / or stator disks (157).

5. A method of coating a pump-active component of a pump, comprising the following steps: Step A) providing the pump-active component composed of a light metal workpiece and having 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 polymerizable sealing precursor, in particular a 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 during at least one of the steps A) to C).

6. A method according to claim 5, wherein, in step C), the solution includes ions and / or ionic compounds.

7. A method according to claim 5 or 6, wherein at least one compound having functional groups from the families of the organic anions, such as of the 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 and aluminates, is included in the solution of step C).

8. A method according to at least one of the claims 5 to 7, wherein the voltage is successively increased during the treatment of the pump-active component.

9. A method according to at least one of the claims 5 to 8, wherein the voltage is between 50 and 300 V.

10. A method according to at least one of the claims 5 to 9, wherein the voltage is applied to the pump-active component using a direct current.

11. A method according to at least one of the 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.

12. A method according to at least one of the claims 5 to 11, wherein the sealing precursor is precipitated in the pores during the electrochemical treatment.

13. A method according to at least one of the claims 5 to 12, wherein the sealing precursor is polymerized in the pore.

14. A pump comprising a pump-active component which can be obtained in accordance with a method according to any one of the claims 5 to 13.

15. A pump according to claim 14, wherein the pump is a pump according to any one of the claims 1 to 4.