Vacuum pump

Abstract

To improve cooling of a vacuum pump as simply and efficiently as possible to enable the vacuum pump to be reliably operated at the limits of thermal and output conditions.SOLUTION: A portion or the entire of the surface of a stator component is subjected to an oxidation treatment, and / or a portion or the entire of the surface of a rotor component is subjected to an oxidation treatment or a coating treatment with a nickel-containing material, the stator component and / or the rotor component comprising a metallic material containing at least one kind of metallic element, and a portion or the entire of the treated stator component surface has an outer layer comprising a compound of the metallic element produced by the oxidation treatment, and / or a portion or the entire of the treated rotor component surface has an outer layer comprising a compound of the metallic element produced by the oxidation treatment, or a portion or the entire of the treated rotor component surface has an outer layer formed by coating with a nickel-containing material and comprising nickel.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a vacuum pump, in particular a turbomolecular pump, comprising a housing and at least one pump stage arranged within the housing, the pump stage having a stator and a rotor which, during operation, rotates about an axis of rotation relative to the stator and interacts with the stator to provide a pumping action. [Background technology]

[0002] Depending on the type and amount of gas being pumped, the rotor of a vacuum pump, particularly a turbomolecular pump (TMP), heats up during operation. In many vacuum applications, pumping large amounts of gas causes the vacuum pump, particularly a turbomolecular pump, to operate at its thermal limit because the rotor reaches the maximum temperature it can reliably be subjected to when subjected to continuous load. Rotor heating can adversely affect its service life and limit the maximum amount of gas that can be pumped by the vacuum pump.

[0003] To operate turbomolecular pumps reliably, the maximum power consumption must currently be limited to prevent excessive thermal demands on the pump, or the rotor temperature must be determined by a sensor during operation and used as a control value. Under certain circumstances, the maximum permissible rotor temperature can nevertheless be reached, even though the maximum drive power of the motor has not yet been extracted.

[0004] Essentially, the generated heat is dissipated by thermal radiation from the rotor to the stator and from there outwards to the (optionally cooled) pump housing. However, improving heat transfer from the rotor to the stator components requires increasing the temperature difference between the relevant surfaces. Therefore, the surface temperature of the stator components must be as much lower as possible than that of the rotor. The physics of heat dissipation dictate that an object can absorb or emit heat better the higher the thermal emissivity ε of its surface, i.e., the ratio of the object's actual radiant power to the radiant power of an ideal black radiator. Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the present invention is therefore to improve the cooling of vacuum pumps, in particular turbomolecular pumps, as simply and efficiently as possible, so that the rotor of the pump has a lower rotor temperature under otherwise identical conditions, thereby enabling the vacuum pump to operate reliably at the limits of its thermal and power requirements. [Means for solving the problem]

[0006] This problem is solved by a vacuum pump according to claim 1.

[0007] Such a vacuum pump, in particular a turbomolecular pump, comprises a housing and at least one pump stage arranged within the housing, the pump stage having a stator and a rotor which, during operation, rotates about a rotation axis relative to the stator and interacts with the stator to provide a pumping action.

[0008] According to the invention, the stator comprises at least one stator component having a stator component surface, a portion of the stator component surface or the entire stator component surface having been treated by oxidation, and / or the rotor comprises at least one rotor component having a rotor component surface, a portion of the rotor component surface or the entire rotor component surface having been treated by oxidation or by coating with a nickel-containing material, the treated stator component and / or the treated rotor component comprises a metallic material containing at least one metallic element, and the portion of the treated stator component surface or the entire treated stator component surface has an outer layer comprising a compound of the metallic element formed by the oxidation treatment, and / or the portion of the treated rotor component surface or the entire treated rotor component surface has an outer layer comprising a compound of the metallic element formed by the oxidation treatment, or the portion of the treated rotor component surface or the entire treated rotor component surface has an outer layer formed by coating with a nickel-containing material and comprising nickel.

[0009] This means that the compound of the metal element is a compound of at least one metal element that is also contained in the metallic material.

[0010] In the present disclosure, the term "oxidation" is not limited to reaction with oxygen or the production of oxides, but should be understood in the usual sense common in the chemical arts to include all redox reactions in which a metal gives up electrons to an oxidant, thereby transitioning to a state having a higher oxidation number. For example, a metal may be oxidized to a metal sulfide. Moreover, preferably, oxidation is the reaction of a metal element to produce an oxygen compound, in particular an oxide, hydroxide, and / or oxyhydroxide of the metal element.

[0011] The oxidation treatment may in particular be anodic oxidation. Anodizing is understood to be an electrochemical treatment in which the stator or rotor part to be treated is brought into contact with an electrolyte solution and connected to a power supply, the stator or rotor part being connected as the anode (positive pole). Preferably, the oxidation treatment is the anodic oxidation of aluminum or an aluminum alloy, also known as "anodic oxidation" or "anodic oxidation process" (electrolytic oxidation of aluminum). The outer layer thus produced is therefore also called an "anodic oxide layer", and the material thus treated is also said to be "anodized".

[0012] The anodizing process is basically known to experts and usually involves a pretreatment of the metal material to clean and expose the metal surface (degreasing, deoxidizing, pickling), the actual anodization (i.e. anodization) to transform the aluminum surface into an outer layer consisting of aluminum oxide and / or aluminum hydroxide, and a post-treatment (optional coloring, compression to close the pores). Anodizing is usually carried out with a direct current, with the stator or rotor part connected as the anode. In this case, the electrolyte solution is typically an aqueous solution of an acid, such as sulfuric acid or oxalic acid.

[0013] Moreover, the method according to the present invention is not limited to anodizing or anodic oxidation of stator or rotor components. The stator or rotor components may also be subjected to other oxidation treatments, particularly coloring oxidation treatments, on their surfaces. Chemical metal coloring treatments are also called chemical metal coloring. This term refers to a method in which a metal or alloy surface reacts by chemical reaction with a dye, producing a colored metal compound, which may in particular be an oxide of the metal. The chemical reaction may be carried out using a coloring solution, in which the stator or rotor component is particularly immersed, or may involve a reaction with a gas (e.g., oxygen), a molten salt, or another dye. Preferably, separately machined, especially machined, surfaces are colored, since these react more quickly and have a more intensive coloring than other surfaces, such as unprocessed, rough, or molded surfaces. Furthermore, in this way, an increased emissivity can also be achieved advantageously on contact surfaces, mating surfaces, or dimensional reference surfaces that must be machined due to tolerances.

[0014] The coloring chemical treatment may be carried out on the surface of stator or rotor components containing copper, copper alloys, aluminum, aluminum alloys, iron alloys, magnesium alloys, nickel and / or nickel alloys as metallic materials.

[0015] Examples of coloring chemical treatments known per se and usable in the present invention are: the formation of sulfur compounds of copper on the surface of copper or copper alloys, for example by treatment with potassium sulfide, ammonium sulfide or sodium thioantimonate; the formation of copper oxygen compounds on the surface of copper or copper alloys, for example by treatment with molten salts consisting of alkali metal nitrites or alkali metal nitrates or by treatment with oxidizing solutions of potassium persulfate, potassium permanganate or potassium chlorate, the formation of oxygen compounds of iron on the surface of iron alloys, for example by heating the steel in air (so-called "bluing"), by treating the steel with molten salts consisting of alkali metal nitrites, alkali metal nitrates or alkali metal dichromates, or by treating it with hot, highly concentrated sodium hydroxide solutions containing simultaneously an oxidizing agent such as sodium nitrate or sodium nitrite (so-called blackening), the formation of colored oxygen compounds on the surface of aluminum or aluminum alloys by treatment with oxidizing solutions, for example sodium chromate or potassium permanganate (so-called modified Bauer Vogel Verfahren, MBV process), the formation of colored oxygen compounds on the surface of magnesium alloys by treatment with oxidizing solutions, for example sodium dichromate and manganese nitrate or copper nitrate, or The formation of sulfur compounds of nickel on the surface of nickel or nickel alloys, for example by treatment with sodium thioantimonate. Bluing and blackening, in particular blackening of iron alloys, are particularly preferred, since they produce extremely thin (<2 μm, preferably ≦1 μm and ≧0.6 μm) wear-resistant oxide layers without significantly changing the dimensions of the components, which is particularly advantageous when coloring contact surfaces, mating surfaces or dimensional reference surfaces.

[0016] The above list is merely exemplary in nature, and the coloring treatments that can be used in the present invention are not limited to the forms listed here.

[0017] The outer layer produced by the oxidation treatment differs from the natural oxide layer on the metal material as well as from a coating in the conventional sense.

[0018] On base metals such as aluminum or titanium, an oxide film naturally forms in air, which acts as a passivation layer and protects the underlying metal from further oxidation. However, this natural oxide layer is generally very thin, typically in the range of a few nanometers. Therefore, the natural oxide layer cannot provide a high thermal emissivity to the surface, nor does it have significant porosity to allow for dye storage.

[0019] In conventional coating methods, an additional layer of a different material is applied to a metal material. Because this additional layer is applied thickly over the entire surface, the dimensional accuracy of the coated component can be impaired. This is undesirable, particularly for contact surfaces, mating surfaces, and dimensional reference surfaces in vacuum pumps. For example, after the coating is applied, the component must be separately processed in an additional work step to locally remove the previously applied coating. Furthermore, such coatings can peel off over time due to a lack of intimate bonding with the underlying material, which can lead to a deterioration in the emissivity of the pump and contamination by the peeled particles.

[0020] Unlike natural air oxidation or conventional coating processes, oxidation treatment of metallic materials involves controlled chemical reactions that convert portions of the metallic material into one or more metal compounds under controlled conditions. In essence, the existing metal surface is modified. This oxidation of the material occurs from the surface of the workpiece to a depth of several micrometers or tens of micrometers, depending on the material and the process variables selected.

[0021] Such layers produced by oxidation treatment have advantages over both natural oxide layers produced by air contact and conventional coatings.

[0022] The layer produced by the oxidation process differs from natural oxide films in that it can significantly increase the thermal emissivity of the surface and, due to its porosity, can store pigments.

[0023] Furthermore, unlike conventional coatings, the layer produced by the oxidation treatment is only partially deposited on the untreated metal surface by growing the oxidized layer into the metal surface. Preferably, the outer layer may be deposited up to 50% of its total thickness, while growing into the metal material to 50% or more of its total thickness on the untreated metal surface. For example, the outer layer may be deposited one-third of its total thickness, while growing into the metal material to two-thirds of its total thickness on the untreated metal surface.

[0024] Surprisingly, it has been found that when all contact surfaces, mating or dimensional reference surfaces of the treated stator and / or rotor components are oxidized, and no portions of the outer layer are subsequently removed again (e.g., in view of required component tolerances or to improve mating and heat transfer), the rotor temperature itself in the vacuum pump can be significantly reduced.

[0025] At the same time, a slight increase in size of the stator or rotor parts, for example of a few micrometers, due to the oxidation treatment in certain places can have a positive effect, since, for example, the resulting slight narrowing of the radial Holweck gap can further increase the power performance of the vacuum pump without threatening dimensional stability.

[0026] As mentioned above, it has also been found that the dimensions of stator and rotor parts processed in accordance with the present invention do not change significantly, and therefore no adjustments to other parts of the vacuum pump are necessary in this regard, and therefore stator and rotor parts processed in accordance with the present invention can be assembled into the same pump housing and combined with the same pump components as corresponding unprocessed stator and rotor parts.

[0027] Oxidation treatments can slightly increase the roughness of the treated surface compared to the corresponding untreated surface. For example, the arithmetic mean roughness Ra or the mean roughness Rz can each increase by a few microns. For anodized aluminum surfaces, for example, an increase in Ra of up to 2 μm can be observed compared to untreated aluminum surfaces for typical layer thicknesses of 10 to 20 μm. This is advantageous, since an increase in surface roughness is usually accompanied by an increase in thermal emissivity. At the same time, a good fit can still be achieved for contact surfaces with other pump components, since only a moderate increase in roughness occurs.

[0028] Unlike conventional coatings, the outer layer produced by the oxidation process is also a component of the workpiece that is intimately bonded to the metallic material rather than being a dissimilar material that is subsequently applied, thereby avoiding spalling or peeling of the outer layer.

[0029] Finally, the outer layer produced by the oxidation treatment also has the advantage of providing effective corrosion protection.

[0030] An outer layer may be produced on a rotor component by coating it with a nickel-containing material according to the present invention. The outer layer thus produced contains nickel and also has the advantage of providing effective corrosion protection for the treated surface. Preferably, the nickel-containing outer layer also has an increased thermal emissivity ε (e.g., at least 0.3) at 50°C compared to an untreated surface, thereby contributing to improved rotor cooling.

[0031] The coating with the nickel-containing material may be, in particular, a nickel plating, and the treated rotor component may therefore be a nickel-plated rotor component. That is, the nickel-containing outer layer may comprise metallic nickel and be deposited on the rotor component surface in a conventional galvanic or currentless manner. This layer may consist essentially of pure metallic nickel, essentially free of other elements, except for unavoidable impurities. Furthermore, this layer may contain, in addition to nickel, other metals, such as zinc, and / or nonmetals, in particular phosphorus, oxygen, or sulfur. In particular, the layer may be deposited electrolessly ("chemical nickel") and / or may contain 3% to 14% by weight of phosphorus. Optionally, the outer layer comprising metallic nickel may additionally be passivated by methods conventional to experts.

[0032] The nickel-containing outer layer is preferably a black nickel layer. In addition to nickel, the black nickel layer also contains zinc and sulfur, particularly in the form of nickel sulfide and zinc sulfide, and may have a high thermal emissivity (e.g., ε≧0.5) at 50°C. The black nickel layer can be galvanically deposited on the component using a suitable commercially available electrolytic solution. The black nickel layer can be applied onto a first nickel layer previously deposited on the rotor component. The first nickel layer can be, for example, galvanically deposited nickel or currentlessly deposited nickel ("chemical nickel," typically containing 3% to 14% by weight of phosphorus).

[0033] Moreover, the nickel-containing outer layer may not contain metallic nickel and may be formed from a nickel compound, such as nickel oxide, and may be formed, for example, by physical vapor deposition (PVD) or chemical vapor deposition (CVD).

[0034] If the rotor component has an outer layer produced by coating with a nickel-containing material, the layer thickness of the nickel-containing outer layer thus produced is preferably 30 μm or less, more preferably 25 μm or less. The layer thickness is even more preferably 15 μm or more, more preferably 20 μm or more. In a possible embodiment, the layer thickness may have a tolerance of ±3 μm around 25 μm, i.e., the layer thickness may be between 22 μm and 28 μm in this embodiment.

[0035] The generated outer layer can cover substantially the entire surface of the stator or rotor component. However, even if an attempt is made to cover the surface of the stator or rotor component as completely as possible, it may be unavoidable, depending on the oxidation method selected, that at least a small portion of the surface of the treated stator or rotor component is not oxidized and therefore does not have an outer layer. In particular, it is conceivable that contact points necessary for the oxidation process (e.g., for establishing electrical contact during anodization) are not covered by the outer layer. The same applies to any coating of the rotor component with a nickel-containing material. Therefore, when the disclosure refers to the "entire" surface or the "entire" surface, this includes substantially the entire surface of the stator or rotor component, but is also understood to refer to a portion of the surface that, for technical reasons, is less than 100%. The treated portion of the surface of the stator or rotor component may be, for example, 90% or more, 95% or more, or 99% or more of the entire surface of the respective stator or rotor component.

[0036] It is desirable to treat the entire surface as much as possible, but if this is not possible for technical reasons in parts of the surface (for example because contact points must be provided for anodizing), preferably parts of the surface that do not participate in heat dissipation by radiation, i.e., for example the radially outer surface of the Holweck stator facing the housing or the radially outer end of the stator blade facing the housing, are left untreated and do not have an outer layer.

[0037] In the present disclosure, the term "treated stator component" refers to a stator component that has been treated by oxidation on part of its surface or on its entire surface. Conversely, in the present disclosure, the term "untreated stator component" refers to a stator component that has not been treated by oxidation on its surface. The terms "treated surface" and "untreated surface" used below should be interpreted accordingly.

[0038] In this disclosure, the term "treated rotor component" refers to a rotor component that has been treated by oxidation or coated with a nickel-containing material on a portion of its surface or on its entire surface. Conversely, in this disclosure, the term "untreated rotor component" refers to a rotor component that has not been treated by oxidation or coated with a nickel-containing material. The terms "treated surface" and "untreated surface" used hereinafter should be interpreted accordingly.

[0039] Thus, the vacuum pump according to the invention comprises at least one treated stator part, at least one treated rotor part, or a combination of at least one treated stator part and at least one treated rotor part. In this case, the treatment of the stator part is always by oxidation, while the treatment of the rotor part can be by oxidation or by coating with a nickel-containing material. Preferably, the vacuum pump according to the invention comprises at least one treated stator part.

[0040] The treated surface of the stator or rotor component preferably has a thermal emissivity ε of at least 0.3 at 50°C, more preferably at least 0.4, even more preferably at least 0.5, particularly preferably at least 0.6, even more particularly preferably at least 0.7, even more particularly preferably at least 0.8, and most preferably at least 0.9. A high emissivity at 50°C is advantageous because this temperature is within the normal operating temperature range of the rotor. This results in particularly effective heat dissipation during operation. The thermal emissivity ε is the total emissivity over the infrared wavelength range from 0.78 μm to 1 mm.

[0041] The thermal emissivity ε of a heated object can be measured using a thermal sensor and an infrared measuring instrument with adjustable emissivity. First, a contact-type thermal sensor is used to determine the actual surface temperature at one point on the heated object. The surface temperature is then detected using an infrared measuring instrument with an emissivity adjusted to 1. The emissivity of the infrared measuring instrument is then varied until the temperature output from the thermal sensor and the infrared measuring instrument match. This allows the actual thermal emissivity of each heated object to be determined.

[0042] Preferably, the entire surface of at least one stator component is treated, which simplifies manufacturing of the stator component, as it is not necessary to care about oxidizing only certain parts of the surface and excluding others.

[0043] However, it may be advantageous to treat only a portion of the surface of at least one rotor component, rather than the entire surface, especially if the rotor is not one-piece but multi-piece. For example, if the rotor component treated according to the present invention is a rotor blade to be attached to a rotor shaft for a multi-piece rotor, the inner diameter of the rotor blade is preferably not treated and therefore does not have an outer layer. Alternatively, the outer layer initially formed on the inner diameter can be removed again by localized post-processing. This has the advantage of improving the fit of the rotor blade to the rotor shaft. Furthermore, since the inner diameter is not involved in heat dissipation by radiation, an increase in emissivity at this point is not necessary.

[0044] If the rotor is not one piece but is constructed in multiple pieces, it may be even more advantageous if the rotor shaft is not treated.

[0045] In a one-piece rotor, the rotor shaft and the blades are made from one piece. This may be the case, for example, when the vacuum pump does not have a Holweck region.

[0046] A rotor constructed in one piece, particularly in a magnetically supported turbomolecular pump, may have a bell-shaped rotor assembly, whereby the magnetic bearings, and possibly also the drive motor of the rotor assembly, are housed in a hollow space within the bell-shaped rotor assembly. The bell-shaped rotor body may have an internal space whose cross-section increases in the axial direction, starting from the high-vacuum side of the rotor assembly perpendicular to the rotation axis. As the cross-section of the internal space of such a bell-shaped rotor body increases in the axial direction, the circumference of the rotor body also increases in the same direction. Based on the bell-shaped configuration of the rotor body, such a rotor assembly is also called a bell-shaped rotor. Outside the rotor body, a bell-shaped rotor usually has multiple pump stages equipped with rotor blades as pumping elements. The rotor blades, together with respective stator vanes (which are not components of the bell-shaped rotor), form each pump stage of the turbomolecular pump. A bell-shaped rotor is provided for each pump stage. Between the rotor blades of the bell-type rotor, there are intermediate chambers, and after the bell-type rotor is assembled to the turbomolecular pump, the stator blades are provided in the intermediate chambers. However, within the scope of this disclosure, a rotor configured as one piece is not necessarily configured as a bell-type rotor.

[0047] If the rotor is constructed as one piece rather than multiple pieces (though not necessarily as a bell rotor, for example), the entire surface of the rotor may be treated, which simplifies manufacturing of the rotor component, as there is no need to worry about treating certain portions of the surface and excluding others.

[0048] In principle, however, it is also conceivable within the scope of the present disclosure to locally remove the outer layer produced by the oxidation treatment again, if necessary, for example by a cutting method. For example, it may be advantageous to first treat a one-piece rotor over its entire surface and then completely or partially remove the outer layer produced thereby again, at least on selected contact, mating or dimensional reference surfaces, such as ball bearing seats, by post-processing.

[0049] However, the outer layer produced by oxidation of the metallic material grows largely within the surface of the metallic material and is only partially adhered to the untreated surface of the metallic material. This means that, in the assembled state of the vacuum pump, dimensional integrity with respect to other components can be guaranteed even if the entire surface of the stator component or rotor is treated and no subsequent removal of the outer layer is performed anywhere on the surface (for example, in the case of stator blades) or if subsequent removal of the outer layer is performed only on parts of the contact surfaces, mating surfaces or dimensional reference surfaces (for example, in the case of ball bearing seats in one-piece rotors). The fact that such post-processing only needs to be performed partially or not at all and yet the required component tolerances can still be met for the contact surfaces, mating surfaces or dimensional reference surfaces themselves again offers the advantage of simplifying the manufacturing method for the stator component or rotor.

[0050] That is, it has been found that, unexpectedly, effective rotor cooling is achieved in conjunction with stator components whose entire surfaces are treated and from whose contact, mating or dimensional reference surfaces no material is removed after oxidation treatment (which would otherwise normally be removed, e.g., to provide better fit and heat transfer at the contact surfaces).

[0051] The treated portion of the surface or the entire treated surface may be colored. This can be achieved by the compound of the metallic element itself being colored, or by the inclusion of a pigment, i.e., a colored substance different from the compound of the metallic element, in the outer layer. It is also conceivable to combine the described means for achieving coloring, i.e., to provide the outer layer with a colored compound of the metallic element that additionally contains a pigment.

[0052] The outer layer produced by oxidation, especially anodization, of a metal material, such as an anodized layer on an aluminum-based material, has a certain degree of porosity. This is advantageous because the resulting adsorption capacity can be utilized to introduce one or more dyes into the pores of the metal compound layer. The resulting coloring of the outer layer can be, for example, blackening. This is usually achieved by first immersing the part in a dye solution after applying the outer layer by oxidation (e.g., anodization), thereby allowing the dye particles to adsorb in the pores, followed by a compression treatment that closes the pores. The compression can be carried out by treatment with boiling water. The dyes that can be used for such coloring, especially blackening, can be both inorganic and organic. They are generally known to experts and are commercially available.

[0053] Suitable organic dyes include, for example, anionic anthraquinone dyes and azo dyes. Inorganic dyes can be used, particularly colored metal compounds, with metals such as chromium, copper, iron, nickel, and cobalt being examples. Examples include blue iron hexacyanoate and black cobalt sulfide. Water-soluble compounds or metal complexes, such as iron(III) ammonium oxalate solution, can be used to form a dip bath for coloring. Coloring can also be carried out in two stages; for example, the anodized object to be colored is first immersed in a cobalt(II) acetate solution and then in an ammonium sulfide solution, which produces black cobalt(II) sulfide in the pores.

[0054] The coloring can increase the desired effect of rotor cooling, since the coloring, in particular the blackening, of the outer layer can result in a further increase in the thermal emissivity compared to a stator component having a colorless, uncolored outer layer. A further advantage of colored or colored outer layers is that such stator or rotor components can already be distinguished purely visually from other, in particular untreated, stator or rotor components.

[0055] The stator component surface treated by oxidation can additionally be post-treated with a polymer, the polymer being preferably fluorinated, particularly preferably perfluorinated. Perfluorinated polymers can be derived from perfluoroolefin monomers. Examples of suitable perfluorinated polymers are polytetrafluoroethylene (PTFE, Teflon). (R) )

[0056] The treated stator component may be a Holweck stator of a Holweck pump stage of a vacuum pump or a stator vane of a turbomolecular pump stage of a vacuum pump.

[0057] Naturally, the treated surface of the Holweck stator absorbs in particular the thermal radiation emitted by the opposing Holweck rotor and therefore, due to the improved thermal emissivity of its surface (compared to the untreated surface of the Holweck stator made of the same metal material), results in increased heat dissipation, in particular across the radial Holweck gap, which allows for lower operating temperatures of the rotor.

[0058] Likewise, it goes without saying that the treated surfaces of the vanes in a turbomolecular pump stage absorb, in particular, the thermal radiation emitted by the rotor blades opposite them, and therefore, due to the improved thermal emissivity of their surfaces (compared to the untreated surfaces of the vanes made of the same metallic material), an increase in heat dissipation across the respective axial gaps is achieved, thereby enabling lower operating temperatures of the rotor.

[0059] The treated stator part may be a dome mounted in a Holweck stage, covering the motor and shielding it from the pump system. The dome surrounds the motor chamber as a wall, i.e., the dome may be wall 221 as shown in FIG. 3. Naturally, the treated surface of such a wall absorbs, in particular, the thermal radiation emitted by the opposing Holweck rotor, and therefore, due to its improved thermal emissivity (compared to the untreated surface of a wall made of the same metal material), an increased heat dissipation across each radial gap is achieved, which allows for a lower operating temperature of the rotor.

[0060] The treated rotor and / or stator parts may be labyrinth seals, which are typically mounted on motors and have a particularly large surface area for absorbing radiant heat due to the (purge gas) labyrinth contained therein. It goes without saying that the treated stator-side surface of such a labyrinth absorbs, in particular, the thermal radiation emitted from the opposing rotor hub, and therefore, due to its improved thermal emissivity (compared to the untreated surface of a labyrinth made of the same metal material), increases the heat dissipation across the respective axial and radial gaps, thereby enabling lower operating temperatures of the rotor. Alternatively or additionally, it may be advantageous to improve the heat dissipation in the region of the labyrinth seal if the rotor-side surface of the labyrinth is treated according to the invention.

[0061] The turbomolecular pump stage of the vacuum pump may have several rotor blades, in which case several rotor blades or all rotor blades of the turbomolecular pump stage are treated, which is advantageous because in this way the greatest possible amount of heat can be removed by radiation in the turbomolecular pump stage.

[0062] A Holweck pump stage of a vacuum pump has a radially outer Holweck stator and one or more radially inner Holweck stators, where either all Holweck stators are treated or only the radially outer Holweck stator is treated. In the present disclosure, a "radially outer" Holweck stator should be understood as the radially outermost Holweck stator of the vacuum pump. Correspondingly, a "radially inner" Holweck stator should be understood as all Holweck stators located further inward in the radial direction of the vacuum pump than the radially outer Holweck stator.

[0063] If all Holweck starters are treated, the advantage is obtained of particularly effective heat dissipation in the Holweck pump stages and therefore particularly effective rotor cooling.

[0064] However, it may be advantageous if only the radially outer Holweck stators are treated, while at the same time the radially inner Holweck stators or all of the radially inner Holweck stators are untreated. Even tighter tolerances must be maintained along the radially inner Holweck stators than along the radially outer Holweck stators. Although the outer layer produced by the oxidation treatment of the metallic material mostly grows into the surface and is only partially adhered, it may nevertheless be advantageous to omit the treatment on the radially inner Holweck stators, since the resulting absence of the outer layer ensures dimensional accuracy relative to adjacent parts and reliable operation of the pump.

[0065] Preferably, the vacuum pump may have at least one turbomolecular pump stage with a plurality of stator vanes and at least one Holweck pump stage with a radially outer Holweck stator and one or more radially inner Holweck stators, where in at least one turbomolecular pump stage, in particular all stator vanes are treated, and in at least one Holweck pump stage, in particular all Holweck stators are treated or only the radially outer Holweck stator is treated. At the same time, the surfaces of the plurality of stator vanes, in particular all stator vanes, and the surface of the at least one Holweck stator have increased emissivity, which in this embodiment allows for particularly effective and uniform heat removal and rotor cooling.

[0066] In another embodiment, the vacuum pump may have at least one turbomolecular pump stage having a plurality of stator vanes and at least one Holweck pump stage having a radially outer Holweck stator and one or more radially inner Holweck stators, wherein the stator vanes of the or each turbomolecular pump stage are untreated and only the radially outer Holweck stator of the or each Holweck pump stage is treated.

[0067] In another embodiment, the vacuum pump may have at least one turbomolecular pump stage comprising a plurality of stator vanes and at least one Holweck pump stage comprising a radially outer Holweck stator and one or more radially inner Holweck stators, wherein in the or each turbomolecular pump stage a plurality, in particular all, of the stator vanes are treated, and in the or each Holweck pump stage all Holweck stators are untreated.

[0068] In another embodiment, the vacuum pump may have at least one turbomolecular pump stage with a plurality of stator vanes, in which case at least one turbomolecular pump stage or each turbomolecular pump stage has a plurality of, in particular all, stator vanes treated, in which case the vacuum pump does not have a Holweck pump stage.

[0069] When a vacuum pump has turbomolecular pump stages with spacer rings for the stator vanes, preferably none of the spacer rings have a surface treated by oxidation. That is, when a vacuum pump has one or more treated stator vanes and / or at least one treated Holweck stator on the one hand and only untreated spacer rings on the other hand, unexpectedly, under the same conditions, a lower rotor temperature is achieved than in a vacuum pump with treated spacer rings of otherwise identical construction. Therefore, to achieve optimal radiation and rotor cooling, it is particularly preferred that several, in particular all, stator disks in a turbomolecular pump stage are treated, none of the spacer rings in a turbomolecular pump stage are treated, and at least one Holweck stator in a Holweck pump stage is treated, in particular, where the radially outer Holweck stator is treated or all Holweck stators are treated.

[0070] The terms "spacer ring" and "distance ring" are considered interchangeable in this disclosure.

[0071] It is also possible for the housing of the vacuum pump to be treated by oxidation on at least part of its surface, but it is preferred if the entire surface of the housing is left untreated.

[0072] When the vacuum pump has at least one stator part that has been treated by oxidation, the rotor that interacts with the stator to produce the pumping action may have a completely untreated surface, i.e., not treated by oxidation or otherwise coated, in which case preferably the entire surface of all rotor parts is untreated, which means that in this embodiment the rotating parts of the vacuum pump are not treated, and therefore only untreated rotating parts are provided.

[0073] Furthermore, the rotor, which interacts with the stator to produce a pumping action, may have a fully or partially treated surface, in particular at least one blade, although in multi-piece rotors the rotor shaft, and possibly the Holweck hub (if present) and the Holweck rotor (if present), preferably remain untreated. Furthermore, rotors with treated rotor parts may be used in vacuum pumps configured without Holweck stages, in which case the rotor shaft preferably remains untreated if the rotor is configured in a multi-piece configuration.

[0074] By "treated" surface of a rotor or rotor component is understood in the present disclosure a surface that has been subjected to an oxidation treatment or a nickel-containing coating in the manner described above for a stator component. The material of the rotor component whose surface is treated is preferably aluminum, an aluminum alloy, titanium or a titanium alloy.

[0075] In the present disclosure, an oxidized roller component surface is in particular a surface that has been treated by anodic oxidation ("anodization"). Preferably, the oxidized rotor component surface is additionally post-treated with a polymer, with the polymer being particularly preferably fluorinated, and more particularly preferably perfluorinated. The fluorinated polymer may be derived from a perfluoroolefin monomer. Examples of suitable fluoropolymers are polytetrafluoroethylene (PTFE, Teflon). (R) )

[0076] In a preferred embodiment, the treated rotor component is a blade made of aluminum, an aluminum alloy, titanium or a titanium alloy, the blade having a surface treated by anodizing, on which an oxide layer containing aluminum oxide or titanium oxide is produced, the oxide layer additionally being post-treated with a perfluorinated polymer.

[0077] The vacuum pump according to the present invention may have rotor blades and / or stator vanes that are optically dense when viewed in the axial direction. However, preferably, at least the first rotor blade and / or the first stator vane are not optically dense when viewed from the high vacuum side. Additionally, it may be advantageous if the second rotor blade and / or the second stator vane, respectively, are not optically dense. It may also be advantageous if the first three rotor blades and / or the first three stator vanes, respectively, are not optically dense. The term "optically dense" within the scope of this disclosure is understood to mean that there is no direct line of sight between the two sides of the rotor blade or stator vane, respectively, when viewed in the axial direction. This configuration is advantageous and can minimize backflow losses within the pump. The visual density can be adjusted, for example, with respect to the degree of overlap between the individual blades. When the blades are visually dense, there are no gaps between the blades when viewed in the axial direction.

[0078] The blades of the turbomolecular pump stage that are visible on the high vacuum side, i.e., the rotor blades and / or stator vanes of the turbomolecular pump stage that are visible in the observation direction from the high vacuum side, may remain at least partially untreated. The observation direction from the high vacuum side may be an axial observation direction. However, the observation direction from the high vacuum side is not limited to the axial direction and may include a viewing angle that deviates from the axial observation direction by an angle greater than 0° and less than 90°. Thus, the blades that are visible on the high vacuum side may also be understood as blades that remain visible at any viewing angle at any rotor position as viewed from the high vacuum side, and this may include blades that are not visible from the high vacuum side in the axial observation direction.

[0079] For example, the blades visible on the high vacuum side may remain untreated over their entire surface, including the side of the blade axially away from the high vacuum side and not visible therefrom. For example, the blades visible on the first and / or second high vacuum sides may remain untreated, and alternatively or additionally, the stator vanes visible on the first and / or second high vacuum sides may remain untreated. Similarly, all stator vanes visible on the high vacuum side and / or all blades visible on the high vacuum side may remain untreated. Preferably, at least one blade visible on the high vacuum side and / or at least one stator vane visible on the high vacuum side is treated, provided that the treated blade and / or vane visible on the high vacuum side is not the first blade or first vane, respectively, when viewed from the high vacuum side. For example, in a preferred embodiment, a first vane and / or first blade may be untreated, while a second vane and / or second blade, which may also be visible from the high vacuum side, is treated. In such an embodiment, all vanes or blades following the first treated vane or blade as viewed from the high vacuum side, i.e., the third, fourth, etc. vanes or blades, may also be treated.

[0080] The rotor blades and / or stator vanes visible on the high-vacuum side of a turbomolecular pump stage may be treated only on a portion of their surface. For example, the surfaces of these blades can be treated only on the side axially away from the high-vacuum side. Furthermore, the stator vanes visible on the high-vacuum side can also be treated over their entire surface, including the side of the stator vane axially facing the high-vacuum side and visible from there. Similarly, the rotor blades visible on the high-vacuum side can also be treated on their entire surface, including the side of the stator vane axially facing the high-vacuum side and visible from there. In this case, if the inner diameter of the rotor blade remains untreated, this is advantageous for a better fit to the rotor shaft in a multi-piece rotor. Alternatively, the outer layer initially formed on the inner diameter can be removed again by localized post-processing. For example, the first and / or second rotor blades visible on the high-vacuum side can be treated. In this case, alternatively or additionally, the first and / or second rotor blades visible on the high-vacuum side can be treated. Similarly, it is possible to treat all of the stationary vanes visible on the high vacuum side and / or all of the rotating blades visible on the high vacuum side.

[0081] If the blades and / or vanes visible on the high vacuum side are untreated, at least on the side facing the high vacuum side, the desorption process can be avoided and thus a lower pressure can be obtained. Furthermore, this reduces the heat radiation towards the recipient. Heat radiation warming of sensitive devices connected to the vacuum pump on the high vacuum side can adversely affect, for example, the measurement accuracy and is therefore undesirable.

[0082] In contrast, if the rotor blades and / or stator blades visible on the vacuum side are also at least partially treated on their side facing the high vacuum side, this has the advantage of improving the heat transfer from the rotor to the stator, which can also compensate for or overcompensate for any shortcomings in the desorption process or heat dissipation that may occur.

[0083] The compound of the metal element is preferably a compound of the metal element that constitutes the main component of the metallic material, i.e., the compound of the metal element is preferably a compound of the metal element from which the metallic material comprises at least 10 weight percent, preferably at least 25 weight percent, more preferably at least 50 weight percent, particularly preferably at least 75 weight percent, more particularly preferably at least 90 weight percent, and most preferably at least 95 weight percent.

[0084] Since the metal element contained in the compound of metal elements produced by the oxidation treatment is the same as the main component of the metal material, the outer layer is a component tightly bonded to the metal surface of the workpiece resulting from the transformation of the metal surface, which prevents the outer layer from peeling off and ensures that the outer layer grows mostly into the substrate.

[0085] The metallic material contains a metal element, which upon oxidation produces a metal compound from which an outer layer is produced on the treated surface, and the metal element may suitably be aluminum, iron, copper, magnesium, nickel or titanium.

[0086] The stator components comprise a metallic material, which is preferably aluminium, an aluminium alloy, iron, an iron alloy (e.g. steel or cast iron), copper, a copper alloy, magnesium, a magnesium alloy, nickel or a nickel alloy, titanium or a titanium alloy.

[0087] By "alloy" is meant a single-phase or multi-phase metallic material of two or more material systems consisting of two or more starting materials, at least one of which is a metal. The designation of the alloy group is according to the element with the greatest proportion, for example, an aluminum alloy is meant a metallic material in which aluminum is the base metal with the greatest proportion and one or more other alloying elements present in smaller proportions.

[0088] The compound of the metal element is preferably an oxygen compound or sulfur compound of the metal element, more preferably an oxygen compound of the metal element. The sulfur compound may in particular be a sulfide or sulfate. The oxygen compound is in particular an oxide, hydroxide and / or oxyhydroxide of the metal element. The oxide, hydroxide or oxyhydroxide of the metal element may exist as a hydrate. Particularly preferably, the compound of the metal element is an oxygen compound of aluminum, more particularly preferably aluminum oxide, aluminum hydroxide and / or aluminum oxyhydroxide.

[0089] The outer layer produced by the oxidation process may contain substantially a single compound of the metal element (i.e., for example, a single oxide), but may also contain multiple compounds of the metal element, such as an oxide and hydroxide of the metal element or multiple different oxides of the metal element. The metal may be present in multiple oxidation states simultaneously in the outer layer, for example, as iron(II) and iron(III) or copper(I) and (II).

[0090] Of course, the composition of the outer layer produced by oxidation depends not only on the type of oxidizing agent and the method parameters of the oxidation treatment, but also primarily on the composition of the metallic material. For example, oxidation of an alloy of two or more metals may result in the production of an outer layer containing compounds of both metals. However, it is possible that one of the alloying elements is relatively difficult to oxidize and therefore is present in the produced outer layer in a fully or partially unoxidized form. For example, anodizing an Al-Si alloy produces an anodic oxide layer containing, in addition to aluminum oxygen compounds, particles containing elemental silicon. Finally, it is possible that one or more alloying elements are removed from the material surface during the oxidation treatment. Therefore, the relative mass ratio of the alloying elements in the outer layer may differ from the relative mass ratio of the alloying elements in the untreated metallic material.

[0091] In any case, however, preferably, the main component by weight of the outer layer (e.g., at least 10 weight percent, at least 25 weight percent, at least 50 weight percent, at least 75 weight percent, or at least 90 weight percent) is formed by one or more compounds of the metal element that also forms the main component by weight of the metal material. The proportion by weight of this metal element in the metal material and the proportion by weight of the compound of this metal element in the outer layer are preferably at least 10 weight percent for each, more preferably at least 25 weight percent for each, even more preferably at least 50 weight percent for each, particularly preferably at least 75 weight percent for each, even more particularly preferably at least 90 weight percent for each, and most preferably at least 95 weight percent for each.

[0092] As already mentioned above, the outer layer formed during the oxidation treatment is, for the most part, grown into the metallic material. Therefore, the outer layer is only partially deposited on the untreated surface of the metallic material. The total thickness of the layer formed can be influenced by the choice of metallic material, the choice of the method used for the oxidation treatment, and the choice of method variables (e.g., treatment duration). The layer thickness is preferably adjusted so that the outer layer is deposited on the untreated surface of the metallic material to a thickness of 20 μm or less, preferably 10 μm or less, and even more preferably 7 μm or less. Therefore, dimensional accuracy relative to other components can be guaranteed even in areas with tight tolerances, such as the radial Holweck gap.

[0093] Preferably, the outer layer has a total thickness in the range of 15 μm to 30 μm, more preferably in the range of 20 μm to 25 μm.

[0094] In the present disclosure, "total thickness" is understood to be the sum of the thickness of the portion of the outer layer that is deposited against the untreated surface of the metal material and the thickness of the portion of the outer layer that is grown into the metal material against the untreated surface of the metal material.

[0095] The invention will now be described on the basis of exemplary advantageous embodiments with reference to the accompanying drawings. [Brief explanation of the drawings]

[0096] [Figure 1] FIG. 1 shows a perspective view of a turbomolecular pump. [Figure 2] FIG. 2 shows a bottom view of the turbomolecular pump of FIG. [Figure 3] 3 shows a cross-sectional view of the turbomolecular pump taken along the section line AA shown in FIG. 2. [Figure 4] 3 shows a cross-sectional view of the turbomolecular pump taken along the cutting line BB shown in FIG. 2. [Figure 5] 3 shows a cross-sectional view of the turbomolecular pump taken along the cutting line CC shown in FIG. 2. [Figure 6] 1 shows a schematic cross-sectional view of a conventional vacuum pump, not according to the invention, for comparison purposes. [Figure 7] 1 shows a schematic cross-sectional view of a vacuum pump according to the present invention according to a first embodiment. [Figure 8] 1 shows a schematic cross-sectional view of a vacuum pump according to the present invention according to a second embodiment. [Figure 8A] 2A shows a schematic cross-sectional view of a vacuum pump according to the present invention according to embodiment 2A. [Figure 9] 10 shows a schematic cross-sectional view of a vacuum pump according to the present invention according to Example 3. [Figure 10] 10 shows a schematic cross-sectional view of a vacuum pump according to the present invention according to Example 4. [Figure 10A] 4A shows a schematic cross-sectional view of a vacuum pump according to the present invention, according to Example 4A. [Figure 11] 5 shows a schematic cross-sectional view of a vacuum pump according to the present invention according to Example 5. [Figure 12] 10 shows a schematic cross-sectional view of a vacuum pump according to the present invention according to Example 6. [Figure 13] 10 shows a schematic cross-sectional view of a vacuum pump according to the present invention according to Example 7. [Figure 14] 10 shows a schematic cross-sectional view of a vacuum pump according to the present invention according to Example 8. [Figure 15] 4 shows the measured rotor temperature plot against rotor rotation speed for a pump according to the invention according to Example 4 and a pump not according to the invention according to the comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0097] The turbomolecular pump 111 shown in Figure 1 has a pump inlet 115 surrounded by an inlet flange 113. A recipient (not shown) may be connected to the pump inlet 115 in a manner known per se. Gas coming from the recipient can be drawn in from the recipient via the pump inlet 115 and pumped through the pump to a pump outlet 117. An auxiliary vacuum pump, such as a rotary vane pump, may be connected to the pump outlet 117.

[0098] The inlet flange 113 forms the upper end of a housing 119 of the vacuum pump 111 in the orientation of the vacuum pump according to Fig. 1. The housing 119 has a lower part 121. Arranged laterally on the lower part 121 is an electronics housing 123. The electronics housing 123 accommodates electrical and / or electronic components of the vacuum pump 111, for example for operating an electric motor 125 (see also Fig. 3) arranged in the vacuum pump. The electronics housing 123 is provided with a number of connections 127 for accessories. Furthermore, a data interface 129 (for example according to the RS485 standard) and a current supply connection 131 are arranged on the electronics housing 123.

[0099] There are also turbomolecular pumps that do not have this type of attached electronics housing, but are connected to external drive electronics.

[0100] The housing 119 of the turbomolecular pump 111 is provided with a ventilation inlet 133, particularly in the form of a ventilation valve. The vacuum pump 111 can be vented via the ventilation inlet 133. A seal gas connection 135 (also called a purge gas connection) is also arranged in the region of the lower part 121. A purge gas can be introduced into a motor chamber 137 via the seal gas connection 135 to protect the electric motor 125 (see, for example, FIG. 3 ) from the gas pumped by the pump. The electric motor 125 is accommodated in the motor chamber 137 of the vacuum pump 111. Two coolant connections 139 are also arranged in the lower part 121. One coolant connection serves as a coolant inlet and the other as an outlet. A coolant can be introduced into the vacuum pump for cooling purposes. The other turbomolecular vacuum pump present (not shown) is operated exclusively air-cooled.

[0101] The underside 141 of the vacuum pump can be used as a base, so that the vacuum pump 111 can be operated in a vertical position relative to the underside 141. Moreover, the vacuum pump 111 can be fixed to the recipient via the inlet flange 113 and thus operated in a suspended state, so to speak. Furthermore, the vacuum pump 111 can be configured so that it can be operated even when oriented in a different direction than that shown in FIG. 1. Vacuum pump configurations are also possible in which the underside 141 can be arranged not only facing downwards, but also facing sideways or upwards. In this case, any angle is conceivable in principle.

[0102] In particular, other turbomolecular vacuum pumps (not shown) that exist, which are larger than the pump shown, cannot be operated in a vertical position.

[0103] 2 further comprises various screws 143. These screws 143 secure components of the vacuum pump, not specifically identified here, to one another. For example, a bearing cover 145 is secured to the lower surface 141.

[0104] Further fastening holes 147 are arranged in the underside 141. Via the fastening holes 147, the pump 111 can be fixed, for example, to a mounting surface. This is not possible with other existing turbomolecular vacuum pumps (not shown), in particular those larger than the pump shown.

[0105] 2 to 5 show a coolant line 148 in which a coolant can be circulated, the coolant being introduced and withdrawn via the coolant connection 139.

[0106] As shown in the cross-sectional views of Figures 3-5, the vacuum pump has multiple process gas pumping stages for pumping process gas acting on a pump inlet 115 to a pump outlet 117.

[0107] A rotor 149 is disposed within the housing 119. The rotor 149 has a rotor shaft 153 that is rotatable about a rotation axis 151.

[0108] The turbomolecular pump 111 has a plurality of turbomolecular pump stages connected in series to provide a pumping action. Each turbomolecular pump stage has a plurality of radially extending rotor blades 155 fixed to the rotor shaft 153 and a plurality of stator vanes 157 arranged between the rotor blades 155 and fixed within the housing 119. In this case, each of a rotor blade 155 and an adjacent stator vane 157 forms a turbomolecular pump stage. The stator vanes 157 are held at a desired axial spacing from one another by spacer rings 159 .

[0109] The vacuum pump further comprises Holweck pump stages arranged radially inside and outside one another and connected in series to provide a pumping action. There are alternative turbomolecular vacuum pumps (not shown) that do not have Holweck pump stages.

[0110] The rotor of the Holweck pump stage includes a rotor hub 161 disposed on the rotor shaft 153 and two cylindrically sided Holweck rotor sleeves 163, 165 fixed to and supported by the rotor hub 161. The Holweck rotor sleeves 163, 165 are oriented coaxially with respect to the rotation axis 151 and engage radially with one another. Two cylindrically sided Holweck stator sleeves 167, 169 are also provided. The Holweck stator sleeves 167, 169 are likewise oriented coaxially with respect to the rotation axis 151 and engage radially with one another.

[0111] The pumping surfaces of the Holweck pump stages are formed by the side surfaces, i.e., the radially inner and / or outer surfaces of the Holweck rotor sleeves 163, 165 and the Holweck stator sleeves 167, 169. The radially inner surface of the outer Holweck stator sleeve 167 faces the radially outer surface of the outer Holweck rotor sleeve 163, forming a radial Holweck gap 171, and together with this outer surface forms the first Holweck pump stage following the turbomolecular pump. The radially inner surface of the outer Holweck rotor sleeve 163 faces the radially outer surface of the inner Holweck stator sleeve 169, forming a radial Holweck gap 173, and together with this outer surface forms the second Holweck pump stage. The radially inner surface of the inner Holweck stator sleeve 169 opposes the radially outer surface of the inner Holweck rotor sleeve 165, forming a radial Holweck gap 175, and together with this outer surface forms the third Holweck pump stage.

[0112] A radially extending channel may be provided at the lower end of the Holweck rotor sleeve 163. The radially outer Holweck gap 171 is connected to the central Holweck gap 173 via the channel. A further radially extending channel may be provided at the upper end of the inner Holweck stator sleeve 169. The central Holweck gap 173 is connected to the radially inner Holweck gap 175 via the channel. This allows multiple Holweck pump stages that engage with each other in series. A connecting channel 179 that leads to the exhaust port 117 may be provided at the lower end of the radially inner Holweck rotor sleeve 165.

[0113] The pumping surfaces of the Holweck stator sleeves 167, 169 each have a plurality of Holweck grooves that extend axially and spirally around the rotation axis 151. On the other hand, the opposing sides of the Holweck rotor sleeves 163, 165 are smoothly formed and pump gas for operating the vacuum pump 111 forward in the Holweck grooves.

[0114] For the rotatable support of the rotor shaft 153, a rolling bearing 181 is provided in the region of the pump outlet 117 and a permanent magnetic bearing 183 is provided in the region of the pump inlet 115.

[0115] In the region of the rolling bearing 181, the rotor shaft 153 is provided with a conical splash nut 185. The splash nut 185 has an outer diameter that increases towards the rolling bearing 181. The splash nut 185 is in sliding contact with at least one scraping element of the working medium reservoir. In other existing turbomolecular vacuum pumps (not shown), a splash screw may be provided instead of a splash nut. This allows for various configurations to be realised, so that the term "splash tip" is also used in this context.

[0116] The working medium reservoir comprises a number of absorbent discs 187 stacked one above the other, which are impregnated with a working medium, e.g., a lubricant, for the rolling bearings 181.

[0117] During operation of the vacuum pump 111, the working medium is transferred by capillary action from the working medium reservoir via the scraping element to the rotating splash nut 185 and is then forced by centrifugal force along the splash nut 185 towards the increasing outer diameter of the splash nut 185 towards the rolling bearing 181, where it performs, for example, a lubrication function. The rolling bearing 181 and the working medium reservoir are enclosed in the vacuum pump by a trough-like insert 189 and a bearing cover 145.

[0118] The permanent magnet type magnetic bearing 183 has a rotor-side bearing half 191 and a stator-side bearing half 193. Each of these has a ring stack, which consists of multiple rings 195, 197 of permanent magnets stacked one above the other in the axial direction. The ring magnets 195, 197 face each other, forming a radial bearing gap 199, with the rotor-side ring magnet 195 positioned radially outward and the stator-side ring magnet 197 positioned radially inward. The magnetic field present in the bearing gap 199 generates a magnetic repulsion force between the ring magnets 195, 197. This repulsion force provides radial support for the rotor shaft 153. The rotor-side ring magnet 195 is supported by a support portion 201 of the rotor shaft 153. The support portion 201 surrounds the ring magnet 195 radially outward. The stator-side ring magnet 197 is supported by a stator-side support portion 203. The support portion 203 extends through the ring magnet 197 and is suspended on radial struts 205 of the housing 119. A ring magnet 195 on the rotor side is fixed parallel to the rotation axis 151 by a cover element 207 connected to the support part 203. A ring magnet 197 on the stator side is fixed in one direction parallel to the rotation axis 151 by a fixing ring 209 connected to the support part 203 and a fixing ring 211 connected to the support part 203. A disc spring 213 may further be provided between the fixing ring 211 and the ring magnet 197.

[0119] An emergency or safety bearing 215 is provided within the magnetic bearing. During normal operation of the vacuum pump, the emergency or safety bearing 215 runs free and only engages if the rotor 149 is displaced excessively radially relative to the stator, thereby forming a radial stop for the rotor 149 so that collisions between rotor-side and stator-side structures are prevented. The safety bearing 215 is configured as a non-lubricated rolling bearing and forms a radial gap with the rotor 149 and / or the stator. This gap prevents the safety bearing 215 from engaging during normal pump operation. The radial displacement that the safety bearing 215 engages is dimensioned to be sufficiently large so that the safety bearing 215 does not engage during normal operation of the vacuum pump, and at the same time is sufficiently small so that collisions between rotor-side and stator-side structures are prevented under all circumstances.

[0120] The vacuum pump 111 includes an electric motor 125 that rotates a rotor 149. The rotor 149 forms an armature of the electric motor 125. A rotor shaft 153 of the rotor 149 extends through a motor stator 217. A permanent magnet assembly may be disposed radially outward or embedded in the portion of the rotor shaft 153 that extends through the motor stator 217. An intermediate chamber 219 is disposed between the motor stator 217 and the portion of the rotor 149 that extends through the motor stator 217, and the intermediate chamber 219 has a radial motor gap. Through the motor gap, the motor stator 217 and the permanent magnet assembly may magnetically interact to transmit a driving torque.

[0121] The motor stator 217 is fixed in the housing in a motor chamber 137 provided for the electric motor 125. A seal gas connection 135 allows a seal gas (also called purge gas, which may be, for example, air or nitrogen) to reach the motor chamber 137. The seal gas protects the electric motor 125 against process gases, for example corrosive parts of the process gas. The motor chamber 137 may be evacuated via the pump outlet 117, i.e., a vacuum pressure is applied to the motor chamber 137 at least approximately, which is achieved by an auxiliary vacuum pump connected to the pump outlet 117.

[0122] A so-called labyrinth seal 223, known per se, may further be provided between the rotor hub 161 and the wall 221 that defines the motor chamber 137. This achieves better sealing of the motor chamber 217, in particular with respect to the radially outer Holweck pump stages.

[0123] The aforementioned pump comprises at least one stator part according to the invention, which interacts with the rotor to provide pumping action in a pump stage, the stator part having the features set out in the dependent claims, in particular a Holweck stator in a Holweck pump stage and / or a stator vane in a turbomolecular pump stage. Alternatively or additionally, the aforementioned pump comprises at least one rotor part according to the invention, which interacts with the stator to provide pumping action in a pump stage, the rotor part having the features set out in the dependent claims, in particular a rotor blade in a turbomolecular pump stage. Advantageously, the pump may comprise a plurality of stator parts and / or rotor parts according to the invention, in particular a plurality of Holweck stators in a Holweck pump stage and / or a plurality of stator vanes in a turbomolecular pump stage and / or a plurality of rotor blades in a turbomolecular pump stage. Particularly preferably, a plurality of stator vanes of a turbomolecular pump stage, in particular all stator vanes of all turbomolecular pump stages, are stator components configured in accordance with the invention, and / or a plurality of rotor blades of a turbomolecular pump stage, in particular all rotor blades of all turbomolecular pump stages, are rotor components configured in accordance with the invention; moreover particularly preferably, additionally, at least the radially outer Holweck stators of all Holweck pump stages or all Holweck stators are stator components configured in accordance with the invention.

[0124] Furthermore, it is advantageous if the turbomolecular pump stage of the aforementioned pump does not have a spacer ring with a treated surface.

[0125] The materials of the rotating components of the vacuum pump are not limited within the scope of this disclosure. For example, rotor components may be made of metallic, ceramic, and / or composite materials.

[0126] The rotor may be constructed in one piece, in which case the rotor is made of a single rotor component and a single material (e.g., an aluminum alloy), in which case the term "rotor component" as used in this disclosure refers to the entire rotor, and the rotor is made of a single rotor component.

[0127] However, it may be advantageous for the rotor to be constructed in a multi-piece configuration, which in this disclosure should be understood as a rotor constructed from at least two separate rotor components. For example, in a multi-piece rotor, individual blades may be attached to a separately manufactured rotor shaft and / or a Holweck rotor sleeve may be attached to a separately manufactured Holweck hub.

[0128] The multi-piece rotor design has the advantage that the individual rotor components can be made of different materials. For example, ceramic blades can be attached to a metallic rotor shaft, or a composite Holweck rotor sleeve can be attached to an aluminum Holweck hub. On the other hand, the multi-piece rotor design offers the advantage of being able to freely select which rotor components are surface-treated and which remain untreated. Thus, for example, rotor designs can be realized in which some blades are treated while others remain untreated.

[0129] Of course, oxidation treatment can only be carried out if the rotor components are made of an oxidizable metallic material, this is not possible with rotors or rotor components made of ceramic or composite materials.

[0130] If the rotor component (or one-piece rotor) is formed from a metallic material, such as aluminum or an aluminum alloy, the rotor component (or one-piece rotor) may not have an outer layer, i.e., may not be subjected to an oxidation treatment, or may have an outer layer produced by an oxidation treatment or may have a nickel-containing coating.

[0131] 6 through 14 show a comparison of schematic cross-sectional views of several differently configured vacuum pumps having both turbomolecular and Holweck pumping stages.

[0132] The housing 19, the rotor shaft 52, and the Holweck rotor's Holweck hub 61, also referred to as the rotor hub, arranged on the rotor shaft 52, which rotates about the axis 51 during operation, do not have an outer layer in the vacuum pumps of Figures 6 to 13 and may be formed in a conventional manner, for example, from untreated aluminum alloy. The cylindrical-sided Holweck rotor sleeve 63 attached to the Holweck hub 61 does not have an outer layer in the vacuum pumps of Figures 6 to 13 and may be formed in a conventional manner, for example, from carbon fiber reinforced plastic (CFRP). However, the radially engaging, also cylindrical-sided Holweck stator sleeves 67, 69 or 68, 70, also referred to as Holweck stators for short, in Figures 6 to 13 differ from one another in terms of their surface characteristics. Furthermore, the stator vanes 57, 58, the spacer rings 59, 60, and the rotor blades 54, 55 differ from one another in terms of their surface characteristics in Figures 6 to 13.

[0133] The system shown in Figure 6 has conventional Holweck stator sleeves 67, 69 that do not have an outer layer and do not have any increased thermal emissivity. The Holweck stator sleeves 67, 69 may be made of, for example, a metallic material that has not been subjected to an oxidation treatment.

[0134] In contrast, the system shown in FIG. 8 includes Holweck stator sleeves 68, 70 according to the present invention, whose dotted surfaces have an outer layer 80 formed by an oxidation process, which includes a compound of metallic elements contained in the metallic material. Therefore, the outer layer 80 has an increased thermal emissivity compared to conventional Holweck stators 67, 69, resulting in improved heat dissipation. This applies to both the radially inner and outer surfaces of the inner Holweck stator 70 and the radially inner surface of the outer Holweck stator 68 in FIG. 8 , resulting in increased heat transfer from the rotor to the stator via the entire radial Holweck gaps 71, 73, respectively. That is, in the embodiment shown in FIG. 8 , each Holweck stator surface has an outer layer 80 formed by an oxidation process, resulting in increased thermal emissivity. This includes the radially inner and outer surfaces as well as the axially upper and lower end surfaces, i.e., the end faces of the Holweck stator sleeves 68, 70, as shown in FIG.

[0135] Of course, other embodiments are conceivable within the scope of the present invention that deviate from the Holweck system configuration shown diagrammatically in Figure 8. For example, it is conceivable that only some of the stator surfaces, rather than all of these surfaces shown dotted in Figure 8, have an outer layer 80 produced by an oxidation treatment.

[0136] In particular, it is conceivable that the radially inner Holweck stator sleeve 69 is not subjected to an oxidation treatment, as shown in Figure 10. This can be advantageous, since the presence of an outer layer 80 with particularly high dimensional accuracy, which is necessary for forming a particularly narrow Holweck gap 73 between the rotor and the stator, can be disadvantageous. In this case, the oxidation treatment and the creation of the outer layer 80 can remain limited to surfaces of other stator components with particularly lower dimensional accuracy requirements, such as the surface of the radially outer Holweck stator sleeve 68 and / or the surfaces of the stator blades 58.

[0137] In particular, as shown in Figures 8A and 10A, it is further conceivable to leave the first stator vane 57, seen from the high vacuum side, untreated, while all other stator vanes 58 are treated.

[0138] The vacuum pump shown in Figures 6 to 14 further comprises a plurality of turbomolecular pump stages connected in series, each of which comprises rotor blades 54, 55 attached to the rotor shaft 52 and stator vanes 57, 58 adjacent to the rotor blades 54, 55, the stator vanes 57, 58 being axially separated from each other by spacer rings 59, 60.

[0139] The spacer ring 59 is not oxidized in Figures 6 to 8 and 10 to 14 and therefore does not have an outer layer 80. The spacer ring 59 may be made of, for example, an untreated aluminum alloy.

[0140] 9, it is possible to use a spacer ring 60 that has been subjected to an oxidation treatment and has an outer layer 80. However, unexpectedly, it has been determined that a spacer ring 60 treated in this manner does not result in improved rotor cooling, even though the resulting thermal emissivity of the spacer ring 60 increases. Therefore, it is preferred that the spacer ring 59 remain untreated.

[0141] The untreated vane 57 of Figures 6, 7, 8A, 10A and 13 differs from the treated vane 58 of Figures 8-14.

[0142] 6 has a conventional vane 57 that does not have an outer layer 80 and does not have any increased thermal emissivity. The conventional vane 57 may be made of, for example, a metallic material that has not been subjected to an oxidation treatment.

[0143] 7 indeed shows a system in which there is only the stator vane 57, which likewise does not have an outer layer 80 and does not have increased emissivity. However, here, unlike the system of FIG. 6, the Holweck stator sleeves 68, 70 have surfaces with an outer layer 80 that have been treated by oxidation. The configuration shown in FIG. 7 is therefore a system in accordance with the present invention.

[0144] In contrast, the system shown in Figures 8-14 includes a stator vane 58 according to the present invention, whose dotted surfaces have an outer layer 80 formed by an oxidation treatment, which includes a compound of metallic elements contained in the metallic material. Thus, the stator vane 58 has an increased thermal emissivity compared to the conventional stator vane 57, resulting in improved heat dissipation. This applies to both the lower and upper surfaces of the treated stator vane in Figures 8-14, thereby increasing heat transfer by heat dissipation from the rotor to the stator throughout the entire axial gap 56. That is, in the embodiment shown in Figures 8-14, the entire treated surface of each stator vane 58 has an outer layer 80 formed by an oxidation treatment, resulting in increased thermal emissivity. This includes the axially upper and lower surfaces as well as the radially inner and outer end surfaces of the treated stator vane 58, as shown in Figures 8-14.

[0145] Of course, it is also possible to deviate from the configuration shown in Figures 8 to 14 in a system according to the invention (not shown) in which the surface of one or more vanes 58 is not treated entirely, but only partially, for example only on the side axially away from the high vacuum side (respectively below in the drawings).

[0146] Figures 8, 9, 10, 11, 12, and 14 show an embodiment in which each stator vane 58 has a treated surface with an outer layer 80. Moreover, rather than treating all of the stator vanes of a vacuum pump according to the present invention, it is also contemplated that one or more stator vanes 57 may be left untreated. Such a configuration is shown in Figures 8A, 10A, and 13, where, as viewed from the high vacuum side (the top side in Figures 8A, 10A, and 13), a first stator vane 57 remains untreated, while a second stator vane 58 is treated and visible from the high vacuum side. The remaining stator vanes 58 in Figures 8A, 10A, and 13 are similarly treated.

[0147] 11-14 illustrate an embodiment in which at least individual rotor components, in addition to stator components, have an outer layer 82 and a treated surface with increased emissivity. The outer layer 82 on the rotor components shown in FIGS. 11-14 may be produced by an oxidation process, as with the stator components, but is not limited to this. That is, unlike the outer layer 80 on the stator components, the outer layer 82 on the rotor components in this disclosure may be produced from a nickel-containing material.

[0148] 11 shows a vacuum pump in which all of the rotor blades 55 have been treated, in addition to all of the stator vanes 58 and all of the Holweck stator sleeves 68, 70. Here, the rotor blades 55 have been treated over their entire surface except for the inner diameter of the rotor blades 55. Leaving the inner diameter of the rotor blades 55 untreated helps the rotor blades 55 to fit better onto the rotor shaft 53, which is also untreated. The Holweck hub 61 and Holweck rotor sleeve 63 are also untreated in this embodiment.

[0149] 12 and 13, embodiments are also conceivable in which some rotor blades 55 and / or stator vanes 58 are treated while other rotor blades 54 and / or stator vanes 57 remain completely untreated. Preferably, at least one rotor blade and / or at least one stator vane visible on the high vacuum side is treated. That is, for example, the second rotor blade and / or second stator vane, respectively, may be treated and simultaneously visible from the high vacuum side (at least at viewing angles deviating from the axial direction). Furthermore, in this case, all vanes following the second stator vane and / or rotor blade, respectively, are also treated.

[0150] FIG. 12 shows a vacuum pump having the same structure as FIG. 11, except that, when viewed from the high vacuum side, the first rotor blade 54 is untreated, while the first stator blade 58 is treated over its entire surface and is visible from the high vacuum side.

[0151] FIG. 13 shows a vacuum pump having the same structure as FIG. 12, except that, as viewed from the high vacuum side, the first rotor blade 57 is also untreated, while the second stator blade 58 is treated over its entire surface and is visible from the high vacuum side.

[0152] The rotors shown in Figures 6 to 13 may have a one-piece structure or a multi-piece structure.

[0153] In contrast, FIG. 14 shows a rotor constructed in one piece. This rotor may be made entirely of, for example, a metallic material, in particular aluminum or an aluminum alloy. In the illustrated embodiment, the entire surface of the one-piece rotor has an outer layer 82 produced by oxidation or coating with a nickel-containing material. Unlike the embodiment of FIGS. 11 to 13, the outer layer 82 is not limited to the rotor blades 55 here, but also covers the Holweck hub 62, the Holweck rotor sleeve 64, and the rotor shaft 53. Although not shown in FIG. 14, the one-piece rotor may also be constructed as a bell-shaped rotor, i.e., have an inner space whose cross section perpendicular to the rotation axis increases axially from the high-vacuum side of the rotor assembly, with the outer circumference of the rotor body also increasing in the same direction.

[0154] The layer thicknesses of the outer layers 80, 82 are greatly exaggerated in Figures 7-14 for clarity and are not shown to scale.

[0155] 6-14 should not be construed as being limited to a single material, but may also include multiple materials within the rotor, stator, spacer ring, or housing. For example, the phrase "rotor material" should be understood to mean that the rotor shown may include rotor components made of various materials.

[0156] The term "viewing direction from the high vacuum side" in the schematic diagrams of Figures 8A, 10A, 12 and 13 should not be construed as being limited to the axial direction only: the viewing angle from the high vacuum side may deviate from the axial direction by more than 0° and less than 90°.

[0157] example In an embodiment hereinafter referred to as Example 2, a vacuum pump according to the present invention has the configuration shown in Figure 8. All of the stator vanes 58 and both Holweck stator sleeves 68, 70 are made of aluminum and have a blackened aluminum oxide layer 80 formed over their entire surfaces by anodizing.

[0158] This anodizing process involves pretreatment (degreasing, pickling, and deoxidization), actual anodizing (i.e., anodizing), and posttreatment (coloring and compaction). To achieve this, each stator blade 58 and Holweck stator sleeve 68, 70, previously manufactured from aluminum in a conventional manner, is first degreased and pickled in an alkaline bath. Subsequent immersion in a dilute acid solution removes any remaining alkaline residue and any existing natural oxide layer (produced by reaction with oxygen in the air) from the aluminum surface. After these pretreatment steps, the stator components are then anodized to a target overall outer layer thickness of 20 to 25 μm. For an overall outer layer thickness of 20 μm, the outer layer is 7 μm thick compared to the untreated aluminum surface. The anodized stator components with the aluminum oxide layer on their surfaces are then immersed in a solution of organic dye. The resulting porous aluminum oxide layer turns black due to the deposition of the dye in the pores. Finally, the stator part so colored is immersed in boiling water, which causes an increase in the volume of the aluminum oxide, resulting in the pores closing.

[0159] The outer layer 80 thus produced covers substantially the entire surface of each vane 58 and both Holweck stator sleeves 68, 70. Only the contact points necessary for carrying out the aforementioned anodization process (e.g., to establish electrical contact during anodization) are not covered by the outer layer 80. Whenever the "entire" surface or the "entire" surface is mentioned in this disclosure, this is also understood to mean, for technical reasons, a portion of the surface that is less than 100%. No post-treatment is carried out to remove part of the outer layer again.

[0160] In contrast, the spacer ring 59 , also made of aluminum, in Example 2 is not anodized and therefore does not have an outer layer 80 .

[0161] Similarly, the housing 19, rotor shaft 52, rotor blades 54, and Holweck hub 61 are made of aluminum, are not anodized, and therefore do not have layer 80. The rotor is constructed in multiple pieces and has a Holweck rotor sleeve 63, which is made of carbon fiber reinforced plastic (CFRP) (and therefore also does not have outer layer 82). This applies not only to Example 2 described here, but also to Examples 1, 2A, 3, 4, 4A, and the comparative example described below.

[0162] In another embodiment, hereinafter referred to as Example 2A, a vacuum pump according to the present invention has the same structure as described above for Example 2, except that the first stator vane 57, as viewed from the high vacuum side, is untreated and does not have an outer layer 80. The configuration of the vacuum pump according to Example 2A is shown in Figure 8A, where the high vacuum side is located at the top end of the illustrated pump in the drawing.

[0163] In another embodiment, hereinafter referred to as Example 1, a vacuum pump according to the present invention has the same structure as described above for Example 2, except that all of the stator vanes 57 are untreated and do not have an outer layer 80. That is, in Example 1, both Holweck stator sleeves 68, 70 have a blackened aluminum oxide layer 80 over their entire surface, which aluminum oxide layer 80 is produced by the anodizing method described above, but none of the stator vanes 57 are anodized. The configuration of the vacuum pump according to Example 1 is shown in Figure 7.

[0164] In another embodiment, hereinafter referred to as Example 3, a vacuum pump according to the present invention has the same construction as described above for Example 2, except that in addition to the entire surfaces of all stator vanes 58 and both Holweck stator sleeves 68, 70, the entire surface of spacer sleeve 59 is also anodized and blackened in accordance with the methods described above. The construction of a vacuum pump according to Example 3 is shown in Figure 9.

[0165] In another embodiment, hereinafter referred to as Example 4, a vacuum pump according to the present invention has the same structure as described above for Example 2, except that of both Holweck stator sleeves, only the radially outer Holweck stator sleeve 68 has a blackened aluminum oxide layer 80 produced by the anodizing method described above. That is, in Example 4, the entire surfaces of all stator vanes 58 and the entire surface of the radially outer Holweck stator sleeve 68 are anodized and blackened according to the method described above, while the radially inner Holweck stator sleeve 69 remains untreated and therefore does not have an outer layer 80. The configuration of a vacuum pump according to Example 4 is shown in Figure 10.

[0166] In another embodiment, hereinafter referred to as Example 4A, a vacuum pump according to the present invention has the same structure as described above for Example 4, except that the first stator vane 57, as viewed from the high vacuum side, is untreated and does not have an outer layer 80. The configuration of the vacuum pump according to Example 4A is shown in Figure 10A, where the high vacuum side is located at the top end of the illustrated pump in the drawing.

[0167] In another embodiment, hereinafter referred to as Example 5, the vacuum pump according to the present invention has the same structure as described above for Example 2, except that all blades 55 also have an aluminum oxide layer 82 formed by anodization. This is an electrolytic process using an external power source, with the blades to be treated connected as the anode, converting the surface of the aluminum material into aluminum oxide. The blades are immersed in a salt solution used as an electrolyte. Oxygen plasma generated in the electrolyte acts on the metal surface, forming a porous but adherent oxide layer on the treated part. While the oxide layer is not colored in Examples 5 to 8 described here, it can optionally be colored, particularly blackened. The oxide layer thus formed grows 50% into the substrate and 50% outward, based on its volumetric increase. Subsequently, the blades 55, which have been treated by the aforementioned oxidation, are post-treated by immersion in PTFE.

[0168] That is, in Example 5, not only the entire surfaces of all stator vanes 58 and both Holweck stator sleeves 68, 70, but also the surfaces of all rotor blades 55 are oxidized, with the inner diameter of each rotor blade 55 remaining untreated. Alternatively, the outer layer initially formed on the inner diameter can be removed again by localized post-treatment. The rotor shaft 52 and Holweck hub 61 remain completely untreated and therefore do not have an outer layer 82. The rotor is constructed in multiple pieces and has a Holweck rotor sleeve 63 made of carbon fiber reinforced plastic (CFRP) (and therefore also does not have an outer layer 82). The configuration of the vacuum pump according to Example 5 is shown in FIG. 11.

[0169] In another embodiment, hereinafter referred to as Example 6, the vacuum pump according to the present invention has the same structure as described above for Example 5, except that the first stator vane 54, as viewed from the high vacuum side, is untreated. That is, in Example 6, the entire surfaces of all stator vanes 58 and both Holweck stator sleeves 68, 70 are coated with a blackened aluminum oxide layer 80 produced by the anodizing method described in Example 2. Additionally, the surfaces of all blades 55, except for the first blade 54, as viewed from the high vacuum side, are also treated by the anodizing method described in Example 5 and post-treated with PTFE, with the inner diameters of the blades 55 being free of an outer layer 82. The absence of an outer layer 82 on the inner diameters of the blades 55 can be achieved by leaving the inner diameters untreated from the beginning, or by removing the outer layer 82 initially produced during the treatment of the blades 55 by localized post-treatment of the inner diameters. The rotor shaft 52 and Holweck hub 61 are left completely untreated and therefore do not have an outer layer 82. The rotor is of multi-piece construction and has a Holweck rotor sleeve 63 made of carbon fiber reinforced plastic (CFRP) (and therefore also without an outer layer 82). When viewed from the high vacuum side, the first stator vanes 58 are anodized and are visible from the high vacuum side. The construction of a vacuum pump according to Example 6 is shown in Figure 12, where the high vacuum side is located at the top of the illustrated pump in the drawing.

[0170] In another embodiment, hereinafter referred to as Example 7, a vacuum pump according to the present invention has the same structure as described above for Example 6, except that the first stator vane 57, viewed from the high vacuum side, is also untreated. In Example 7, the entire surfaces of both Holweck stator sleeves 68, 70, and additionally the entire surfaces of all stator vanes 58, viewed from the high vacuum side except for the first rotor blade 54 and the first rotor vane 57, and the surfaces of all rotor blades 55, are coated with aluminum layers 80, 82 produced by the oxidation method described in Example 2 (for the stator component) or Example 5 (for the rotor blades), respectively, except that the inner diameters of the rotor blades 55 do not have an outer layer 82, and the rotor blades 55 are further post-treated by immersion in PTFE. The absence of an outer layer 82 on the inner diameters of the rotor blades 55 can be achieved by leaving the inner diameters untreated from the beginning, or by removing the outer layer 82 initially produced during the treatment of the rotor blades 55 by local post-treatment of the inner diameters. The rotor shaft 52 and Holweck hub 61 are left completely untreated and therefore do not have an outer layer 82. The rotor is of multi-piece construction and has a Holweck rotor sleeve 63 made of carbon fiber reinforced plastic (CFRP) (and therefore also does not have an outer layer 82). Viewed from the high vacuum side, the second stator vanes 58 are anodized and blackened and are visible from the high vacuum side. The configuration of the vacuum pump according to Example 7 is shown in Figure 13, where the high vacuum side is located at the top of the illustrated pump in the drawing.

[0171] In another embodiment, hereinafter referred to as Example 8, a vacuum pump according to the present invention has a configuration as shown in FIG. 14. As in Example 5, in Example 8, the entire surfaces of both Holweck stator sleeves 68, 70 and all of the stator vanes 58 are coated with a blackened aluminum oxide layer 80 produced by the anodizing method described above. However, unlike Example 5, in Example 8, the rotor is formed from a single piece of aluminum and is coated on its entire surface with an aluminum oxide layer 82. The aluminum oxide layer 82 is produced by the oxidation method described in Example 5 and post-treated with PTFE. That is, in Example 8, the entire rotor is made of aluminum, and all accessible surfaces of the rotor shaft 53, rotor blades 55, Holweck hub 62, and Holweck rotor sleeve 64 are coated with the aluminum oxide layer 82. The configuration of the vacuum pump according to Example 8 is shown in FIG. 14.

[0172] Of course, in Examples 5 to 8, the outer layer 82 attached to the blades 55 or the entire one-piece rotor may alternatively be produced by coating with a nickel-containing material. Likewise, of course, in Examples 5 to 8, the outer layer 82 attached to the blades 55 or the entire one-piece rotor may alternatively be produced by anodizing, for example, by the anodizing method described in Example 2. That is, not only the treated stator component but also the treated rotor component may be anodized, and the stator component and the rotor component may then be treated by the same anodizing method.

[0173] In the comparative example, a vacuum pump not according to the invention has the structure shown in Figure 6. That is, neither the Holweck stator sleeves 67, 69 nor the stator vanes 57 are anodized. They therefore consist of untreated aluminum without an outer layer 80. The same applies to the spacer ring 59, the housing 19, the rotor shaft 53, the rotor blades 54 and the Holweck hub 61. As in Examples 1 to 7, the rotor is constructed in a multi-piece structure, with the Holweck rotor sleeve 63 consisting of carbon fiber reinforced plastic (CFRP) (and therefore also without an outer layer 82).

[0174] The effect of various surface treatments on heat dissipation was experimentally tested on a vacuum pump according to a comparative example and on vacuum pumps according to Examples 1 to 4. All of the vacuum pumps in the examples were identically dimensioned and differed only in which stator components had a blackened anodized layer 80. To determine the effect on heat dissipation, the same amount of gas was pumped through each of the vacuum pumps while the rotational speed was gradually increased and the rotor temperature, which depended on the rotor rotational speed, was measured using an infrared thermometer. The results of these tests are summarized in Table 1.

[0175] [Table 1]

[0176] Here, all examples according to the invention, i.e., when anodized and blackened stator components are used, show a reduction in rotor temperature compared to temperatures measured under otherwise identical test conditions in comparative examples (i.e., in rotors of conventional vacuum pumps having untreated stator components of otherwise identical structure).

[0177] A particularly strong reduction in rotor temperature, i.e., -11°C reduction, is seen in Example 2 when the radially outer Holweck stator sleeve 68, the radially inner Holweck stator sleeve 70, and all stator vanes 58 are anodized and blackened over their entire surfaces. However, unexpectedly, as shown in Example 3, the additional anodizing and blackening of the spacer ring 60 does not result in an even stronger effect, resulting in only a weak reduction of -6°C compared to the rotor temperature of the comparative example. The slight reduction in rotor temperature can be explained by the fact that the coated spacer ring 60 has increased emissivity, but at the same time has poorer heat transfer to the housing than the untreated spacer ring 59.

[0178] In Example 1, both Holweck stator sleeves 68, 70 are anodized and blackened, but the rotor blades 57 are not. A reduction in rotor temperature occurs compared to the comparative example, but is only -1°C, and therefore much less than in Example 2, in which an otherwise identical vacuum pump has additionally anodized and blackened stator blades 58.

[0179] In Example 4, all of the stator vanes 58 and the radially outer Holweck stator sleeve 68 are anodized and blackened over their entire surfaces, while the radially inner Holweck stator sleeve 69 remains untreated. This again results in a significant reduction in rotor temperature of -7°C compared to the comparative example. The plots of measured rotor temperature (y-axis) versus rotational speed (x-axis) for the vacuum pump according to the comparative example (dashed line) and the vacuum pump according to Example 4 (solid line) are shown in Figure 15. Based on this graph, it can be seen that differences in rotor temperature occur throughout the tested rotational speed range and increase towards higher rotational speeds.

[0180] The above examples show that, beyond expectations, in a vacuum pump according to the invention, the treated stator parts used are treated over their entire surface, without the outer layer at the contact, mating or dimensional reference surfaces being subsequently removed, but a significantly improved heat dissipation can be achieved compared to a vacuum pump having an untreated stator part of otherwise identical structure. [Explanation of symbols]

[0181] 19 Housing 51 Rotation axis 52 rotor shaft 53 rotor shaft 54 Moving blade 55 Moving blade 56 Axial clearance 57 Stator blade 58 Stator blade 59 Spacer ring 60 Spacer ring 61 Holbeck hub, rotor hub 62 Holbeck hub, rotor hub 63 Holbeck Rotor Sleeve 64 Holbeck Rotor Sleeve 67 Outer Holbeck Sterling Sleeve 68 Outer Holbeck Sterling Sleeve 69 Inner Holbeck Sterling Sleeve 70 Inner Holbeck Sterling Sleeve 71 Holbeck Gap 73 Holbeck Gap 80 outer layer 82 Outer layer 111 Turbomolecular pump 113 Intake flange 115 Pump intake 117 Pump exhaust port 119 Housing 121 Lower part 123 Electronics Housing 125 electric motor 127 Accessory Connection 129 Data Interface 131 Current supply connection 133 Ventilation intake 135 Seal gas connection 137 Motor Room 139 Coolant Connection 141 Bottom surface 143 Screw 145 Bearing cover 147 Fixed hole 148 Coolant line 149 Rotor 151 Rotation axis 153 rotor shaft 155 Moving blade 157 Stator blade 159 Spacer ring 161 rotor hub 163 Holbeck Rotor Sleeve 165 Holbeck Rotor Sleeve 167 Holbeck Sterling Sleeve 169 Holbeck Sterling Sleeve 171 Holbeck Gap 173 Holbeck Gap 175 Holbeck Gap 179 Connection Channels 181 Rolling bearings 183 Permanent magnet type magnetic bearing 185 Splash Nut 187 discs 189 Insert 191 Rotor side bearing half 193 Stator side bearing half 195 Ring Magnet 197 Ring Magnet 199 Bearing clearance 201 Support part 203 Support part 205 Radial Struts 207 Cover Elements 209 Support Ring 211 Fixing ring 213 Disc spring 215 Emergency bearings or safety bearings 217 Motor Stator 219 Intermediate Room 221 Wall 223 Labyrinth Seal

Claims

1. A vacuum pump, in particular a turbomolecular pump, a housing and at least one pump stage disposed within the housing; the pump stage includes a stator and a rotor that rotates relative to the stator about a rotational axis during operation and interacts with the stator to provide a pumping action; the stator has at least one stator component having a stator component surface, a portion of the stator component surface or the entire stator component surface being treated by oxidation, and / or the rotor has at least one rotor component having a rotor component surface, a portion of the rotor component surface or the entire rotor component surface being treated by oxidation or by coating with a nickel-containing material, the treated stator component and / or the treated rotor component comprises a metallic material containing at least one metallic element; a portion of the treated stator component surface or the entire treated stator component surface has an outer layer comprising compounds of metallic elements produced by the oxidation treatment; and / or a portion of the treated rotor component surface or the entire treated rotor component surface has an outer layer comprising a compound of a metal element produced by an oxidation treatment, or a portion of the treated rotor component surface or the entire treated rotor component surface has an outer layer comprising nickel formed by coating with a nickel-containing material.

2. 2. A vacuum pump according to claim 1, wherein the entire surface of at least one of the stator components is treated.

3. 3. A vacuum pump according to claim 1 or 2, wherein the treated rotor part is a rotor blade of a turbomolecular pump stage of the vacuum pump.

4. 4. A vacuum pump according to claim 1, wherein the turbomolecular pump stage has a plurality of rotor blades, and a plurality of the rotor blades or all of the rotor blades of the turbomolecular pump stage are treated.

5. 5. A vacuum pump according to any one of claims 1 to 4, wherein the treated stator part is a Holweck stator of a Holweck pump stage of a vacuum pump and / or a stator vane of a turbomolecular pump stage of a vacuum pump.

6. 6. A vacuum pump according to claim 5, wherein the turbomolecular pump stage has a plurality of stator vanes, and a plurality of or all of the stator vanes of the turbomolecular pump stage are treated.

7. 7. A vacuum pump according to claim 5 or 6, wherein the Holweck pump stage comprises a radially outer Holweck stator and one or more radially inner Holweck stators, and wherein all of the radially outer and inner Holweck stators are treated or only the radially outer Holweck stator is treated.

8. the vacuum pump comprises at least one turbomolecular pumping stage having a plurality of stator vanes and at least one Holweck pumping stage having a radially outer Holweck stator and one or more radially inner Holweck stators; In at least one turbomolecular pump stage or in each turbomolecular pump stage, all of the stator vanes are treated, or a plurality of the stator vanes are treated and one or more stator vanes are not treated; 8. A vacuum pump according to any one of claims 1 to 7, wherein in at least one or each Holweck pump stage all or only the radially outer Holweck stators of the Holweck stators are treated.

9. the vacuum pump includes at least one turbomolecular pump stage having a plurality of rotor blades; 9. A vacuum pump according to any one of claims 1 to 8, wherein in at least one or each turbomolecular pump stage all blades are treated or a number of blades are treated and one or more blades are untreated.

10. 10. A vacuum pump according to any one of claims 5 to 9, wherein the turbomolecular pump stages have spacer rings for the stator vanes, none of said spacer rings having a surface treated by oxidation.

11. 11. A vacuum pump according to claim 3, wherein at least one stationary vane of a turbomolecular pump stage visible from the high vacuum side of the vacuum pump and / or at least one rotating blade of a turbomolecular pump stage visible from the high vacuum side of the vacuum pump are treated.

12. 12. A vacuum pump according to any one of claims 1 to 11, wherein the metal element is aluminium, iron, copper, magnesium, nickel or titanium, and / or the metal material is aluminium, an aluminium alloy, iron, an iron alloy, copper, a copper alloy, magnesium, a magnesium alloy, nickel, a nickel alloy, titanium or a titanium alloy.

13. 13. The vacuum pump according to claim 1, wherein the compound of the metal element is an oxygen compound or a sulfur compound of the metal element.

14. 14. A vacuum pump according to any one of claims 1 to 13, wherein the outer layer is applied to an untreated surface of the metallic material in a thickness of 20 μm or less, preferably 10 μm or less, more preferably 7 μm or less.

15. 15. A vacuum pump according to any one of the preceding claims, wherein the outer layer produced by oxidation has a total thickness in the range of 15 to 30 μm, preferably in the range of 20 to 25 μm.

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