Vacuum pump and method for producing a stator component for a stator of a vacuum pump

Abstract

The invention relates to a vacuum pump, in particular a turbomolecular pump, with a housing and at least one pump stage arranged in the housing, comprising a stator and a rotor rotating relative to the stator about an axis of rotation during operation and cooperating with the stator to effectively pump, wherein the stator has at least one stator component with a surface having a first part and a second part different from the first part, and wherein the second part of the surface is uncoated and has a thermal emissivity ε of at least 0.25, preferably at least 0.3, at 50°C.

Description

[0001] The invention relates to a vacuum pump, in particular a turbomolecular pump, comprising a housing and at least one pump stage arranged in the housing, which includes a stator and a rotor that rotates about an axis of rotation relative to the stator during operation and interacts with the stator to effectively pump. The invention further relates to a method for manufacturing a stator component for a stator of a vacuum pump, in particular a turbomolecular pump.

[0002] Depending on the type and quantity of gas being pumped, the rotor of a vacuum pump, especially a turbomolecular pump (TMP), heats up during operation. In many vacuum applications, pumping a large volume of gas causes the vacuum pump, particularly a turbomolecular pump, to operate at its limit because the rotor reaches the maximum temperature at which it can reliably withstand continuous stress. This rotor heating can negatively impact its service life and limit the maximum volume of gas that the vacuum pump can handle.

[0003] In principle, the heat generated can be transferred via thermal radiation from the rotor to the stator and from there outwards to a (possibly cooled) pump housing. However, improving heat dissipation from the rotor to a stator component requires increasing the temperature difference between the surfaces involved. The surface temperature of the stator component must therefore be as much lower as possible than that of the rotor. According to the physical principles of thermal radiation, a body can absorb or emit heat more efficiently the higher the thermal emissivity ε of its surface, i.e., the ratio of its actual radiative power to that of an ideal blackbody radiator.

[0004] The prior art proposes coating the surfaces of parts of the stator. Patent EP 2 775 148 B1 discloses stator components whose surfaces are partially coated with a nickel oxide layer or an aluminum oxide layer, thereby ensuring improved heat transfer through the stator. However, to achieve the necessary dimensional accuracy on certain stator surfaces, such as outer contact surfaces or the radial gap adjacent to the rotor and directly opposite the web tips, the oxide layer must be removed from the stator component after application, or the corresponding surface sections must be protected by masking before the oxide layer is applied.In both cases, the process is complex because, in addition to the two always necessary steps of primary forming and post-processing of the stator component, a coating process as well as further steps for the local removal or keeping away of the coating material must be carried out. Furthermore, coatings can detach from the underlying material over time, which can lead to a deterioration of the emissivity and contamination of the pump by detached particles. US 2015 / 0354577 A1 also describes stator disks made of an aluminum alloy whose surfaces are partially coated with an aluminum oxide layer. US 2020 / 040910 A1 also discloses a vacuum pump according to the prior art of the present invention.

[0005] The object of the invention is therefore to improve the cooling of a vacuum pump, in particular a turbomolecular pump, in the simplest possible way so that a rotor of the pump can be operated at a lower rotor temperature under otherwise identical conditions.

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

[0007] Such a vacuum pump, in particular a turbomolecular pump, with a housing and at least one pumping stage arranged in the housing, comprises a stator and a rotor rotating around an axis of rotation relative to the stator during operation and cooperating with the stator to effectively pump, wherein the stator has at least one stator component with a surface having a first part and a second part different from the first part.

[0008] According to the invention, the second part of the surface of the stator component is uncoated, and the second part of the surface has a manufacturing-related roughness in the range of 3 µm or more, preferably 5 µm or more, more preferably 10 µm or more, even more preferably 20 µm or more, particularly preferably 30 µm, most preferably 40 µm or more, most preferably 50 µm or more, expressed as mean roughness depth Rz according to DIN EN ISO 4287:2010-07, wherein the manufacturing-related roughness of the second part of the surface is not changed by separating post-processing, and wherein the first part of the surface has been subjected to post-processing by separating, in particular by machining.

[0009] In order to achieve the best possible vacuum-technical properties of the stator component, the roughness of the second part of the surface of the stator component is preferably 500 µm or less, more preferably 400 µm or less, even more preferably 300 µm or less, particularly preferably 250 µm or less, very preferably 200 µm or less, even more preferably 150 µm or less, and most preferably 100 µm or less. For example, the roughness of the second part of the surface of the stator component is in a range of preferably 3 µm to 500 µm, more preferably 5 µm to 400 µm, even more preferably 10 µm to 300 µm, particularly preferably 20 µm to 250 µm, most preferably 30 µm to 200 µm, even more preferably 40 µm to 150 µm, and most preferably 50 µm to 100 µm.However, it is understood that any other combinations of the aforementioned preferred upper and lower limits, not explicitly listed here, are also possible and that these combinations also represent preferred roughness ranges.

[0010] Alternatively, the above problem can be solved by the features of claim 4.

[0011] According to this alternative of the invention, the second part of the surface of the stator component is uncoated, and the second part of the surface has a coloration, wherein the coloration is obtained by adding at least one non-metallic inorganic coloring agent to a starting material used in the manufacture of the stator component, i.e. a metal or an alloy, and wherein the stator component is a Holweck stator of a Holweck pump stage or a spacer ring of a turbopump stage.

[0012] In an unclaimed embodiment, the second portion of the stator component's surface is uncoated and has a thermal emissivity ε of at least 0.25, preferably at least 0.3, at 50°C. A high emissivity at 50°C is advantageous because this temperature is within the range of the rotor's typical operating temperature. This results in particularly effective heat dissipation during operation.

[0013] The thermal emissivity ε of the second part of the surface is preferably at least 0.4, more preferably at least 0.5, particularly preferably at least 0.6, very preferably at least 0.7, even more preferably at least 0.8, and most preferably at least 0.9 at 50°C.

[0014] In particular, the thermal emissivity ε of the second component can be higher than that of the first component.

[0015] The thermal emissivity ε is a total emissivity over the infrared wavelength range from 0.78 µm to 1 mm.

[0016] The thermal emissivity ε of a heated object can be measured using a thermocouple and an infrared thermometer with adjustable emissivity. First, the actual surface temperature at a specific point on the heated object is determined using the thermocouple. Then, the surface temperature is measured with the infrared thermometer, initially set to an emissivity of 1. The emissivity setting on the infrared thermometer is then varied until the temperatures read by the thermocouple and the infrared thermometer match. This allows the actual thermal emissivity of a given heated object to be determined experimentally.

[0017] In a further, unclaimed embodiment, the second part of the surface of the stator component has a surface finish resulting from the manufacturing process and not altered by separating post-processing or coating.

[0018] Preferably, the manufacturing-related surface finish of the second part of the surface of the stator component is a roughness in the range of 3 µm or more, preferably 5 µm or more, more preferably 10 µm or more, even more preferably 20 µm or more, particularly preferably 30 µm, most preferably 40 µm or more, most preferably 50 µm or more, and / or a coloring, in particular wherein the coloring has been obtained by adding at least one coloring agent to a starting material used in the manufacture of the stator component.

[0019] In order to achieve the best possible vacuum-technical properties of the stator component, the roughness of the second part of the surface of the stator component is preferably 500 µm or less, more preferably 400 µm or less, even more preferably 300 µm or less, particularly preferably 250 µm or less, very preferably 200 µm or less, even more preferably 150 µm or less, and most preferably 100 µm or less. For example, the roughness of the second part of the surface of the stator component is in a range of preferably 3 µm to 500 µm, more preferably 5 µm to 400 µm, even more preferably 10 µm to 300 µm, particularly preferably 20 µm to 250 µm, most preferably 30 µm to 200 µm, even more preferably 40 µm to 150 µm, and most preferably 50 µm to 100 µm.However, it is understood that any other combinations of the aforementioned preferred upper and lower limits, not explicitly listed here, are also possible and that these combinations also represent preferred roughness ranges.

[0020] In the present disclosure, the term "roughness" shall be understood to mean a mean roughness depth Rz according to DIN EN ISO 4287:2010-07, unless expressly stated otherwise.

[0021] A stator component according to the invention, whose surface has an increased emissivity ε in at least its second section, can enhance heat transfer both from the rotor to the stator and from the stator to the housing. At the same time, the second section is uncoated, which improves the resistance and durability of the stator component compared to coated components. Furthermore, the stator component according to the invention is easy to manufacture because the second section can be left in the state it is in immediately after primary forming. Unlike in the prior art, the present invention allows a surface with increased emissivity to be obtained directly without any post-treatment being necessary.

[0022] Although the present invention offers several alternative ways of solving the problem it addresses, the features and embodiments designated as optional, preferred and / or advantageous always refer to all alternatives of the invention mentioned herein, unless expressly stated otherwise.

[0023] It is particularly preferred if the first portion of the stator component's surface has undergone post-processing, especially by cutting, particularly by machining. This makes the first portion especially suitable for forming those surfaces of a stator component where high dimensional accuracy is required. It is particularly advantageous if, in addition, the second portion is not post-processed by cutting, particularly by machining. This not only reduces the post-processing effort but also achieves a high surface roughness and, consequently, a high thermal emissivity of the second surface portion. This results in the significant advantage that a surface portion with increased emissivity is obtained as a direct result of manufacturing, without any further post-processing.In current technology, an increase in emissivity can only be achieved through a cumbersome post-treatment process in which a coating must be applied to the stator component.

[0024] Within the scope of the present invention, it is not fundamentally excluded to subject the second part of the surface to post-processing in addition to the first part, for example, post-processing by cutting, in particular by machining. However, it is preferred that the roughness of the second part of the surface does not fall below a value of 3 µm, more preferably 5 µm, even more preferably 10 µm, particularly preferably 20 µm, most preferably 30 µm, even more preferably 40 µm, and most preferably 50 µm.

[0025] Furthermore, within the scope of the present invention, it is also possible to perform a post-treatment of the second part of the surface, which leads to an increase in the roughness of the second part. Such roughening of the second part of the surface can be achieved, for example, by breaking out a support structure, laser structuring, grinding, or sandblasting, preferably by breaking out a support structure or laser structuring, and particularly preferably by laser structuring.

[0026] The term "breaking out a support structure" refers to the process of incorporating a support structure into at least one area of ​​the stator component to be roughened (i.e., at least part of the second surface area) during the initial forming of the stator component, particularly in additive manufacturing processes such as laser sintering or laser melting. This roughened area could, for example, be a groove in a Holweck stator. After the initial forming process, the support structure, which might be honeycomb-like, can be mechanically broken out of the second surface area of ​​the stator component, for example, manually. This method allows for the achievement of particularly high surface roughness.

[0027] Such a breaking away of support structures can also be considered part of the manufacturing process and is therefore not a post-treatment. In this case, the surface finish or roughness resulting from the breaking away is a manufacturing-related roughness.

[0028] Furthermore, it is advantageous if the first portion of the surface, in the assembled state of the pump stage, forms at least a partial contact, mating, or dimensioned surface relative to one or more other components of the vacuum pump. The first and second portions of the surface can thus have complementary or even mutually exclusive functions. While the second portion of the surface exhibits properties that ensure the highest possible emissivity, such as high roughness, the first portion can be designed, for example through machining, to meet the tolerances required at specific points in the vacuum pump and / or to provide a good fit and / or good heat transfer to pump components directly adjacent to the first portion.

[0029] Preferably, the stator component is a Holweck stator of a Holweck pump stage or a spacer ring of a turbopump stage. This improves heat dissipation in the Holweck pump stage, the turbopump stage, or both stages simultaneously, and reduces the risk of overheating of the respective rotors or a common rotor.

[0030] If the stator component is a Holweck stator, it is particularly preferred that the first portion of the surface forms the tips of the webs and / or the outer surface of the Holweck stator. In the pump's operating state, the tips of the webs between the slots of the Holweck stator border the radial gap between the rotor and stator, also known as the Holweck gap, and are therefore located directly opposite the rotor at a short distance. High dimensional accuracy is required at these points for the proper functioning of the Holweck pump stage. This high accuracy is also necessary on the outer surface of a Holweck stator for proper fitting into the pump housing and to ensure good heat transfer to surrounding parts of the pump housing, regardless of whether the contact surface is designed for press-fitting or screw mounting.It is therefore particularly preferred that the first part of the surface, which forms the web tips and / or the outer surface of the hollow stator, be machined by separating, in particular by machining.

[0031] If the stator component is a hollow stator, it is, alternatively or additionally to the above, particularly preferred that the second portion of the surface forms at least sections of the slots, and in particular the entire slots of the hollow stator. The slots do not have to meet the highest dimensional accuracy requirements and can therefore be used to optimize the emissivity of the hollow stator. For example, due to tolerances, it is possible to leave the surface of the hollow stator slots in a state with high manufacturing-related roughness in order to achieve a correspondingly high thermal emissivity.

[0032] If the stator component is a spacer ring of a turbopump stage, it is particularly preferred that the first portion of the surface forms the contact points with adjacent components. These adjacent components can be, for example, spacer rings, stator disks, or a pump housing. As previously explained using the example of hollow-core stators, high dimensional accuracy is required at such contact surfaces to ensure a precise fit and optimal heat transfer. Therefore, it is particularly preferred that the first portion of the surface, which forms the contact surfaces of the spacer ring with other parts of the pump, be machined, especially by cutting.

[0033] If the stator component is a spacer ring of a turbopump stage, it is, alternatively or additionally to the above, particularly preferred that the second portion of the surface forms at least sections of the inner diameter, in particular the entire inner diameter of the hollow stator. The inner diameter is subject to less stringent dimensional accuracy requirements and can therefore be used to optimize the emissivity of the spacer ring. Along the inner diameter of the spacer ring, it is possible, for example, to leave the surface with a high manufacturing-related roughness to achieve a correspondingly high thermal emissivity, due to tolerance limitations.

[0034] Preferably, the stator component is manufactured using a casting process, a sintering process, or an additive manufacturing process. These primary forming processes share the advantage of enabling the production of parts with high manufacturing-related roughness and a resulting high thermal emissivity. A further advantage of these processes is that they allow the incorporation of colorants into the material being formed.

[0035] Casting, i.e., filling a mold with molten material followed by solidification, is a particularly simple and cost-effective primary forming process for producing a stator component that meets vacuum engineering requirements. If the stator component is a casting, the advantage is that the material can be directly transformed from its formless liquid state into a near-net-shape form. A mold with a textured surface is preferably used, which advantageously allows for targeted control of the roughness of at least part of the surface of the cast stator component.

[0036] The casting process used in the present invention is not limited in principle, and the stator component can be produced, for example, by static casting (gravity or stationary casting) or, preferably, by dynamic casting (in particular centrifugal casting, low-pressure casting, or pressure casting). The stator component is particularly preferably produced by pressure casting. In this process, the molten metal is forced into a permanent mold under high pressure. This method offers the advantage of very precise contour reproduction. The pressure casting process can particularly preferably be a vacuum pressure casting process. This offers the advantage of achieving higher material quality because less air and other gases are trapped in the material, thus reducing the porosity of the casting and increasing its density and pressure tightness.Instead of completely liquefied materials, partially liquid or doughy materials can also be used as casting materials (so-called thixo- or rheo-casting).

[0037] If the stator component is a casting, a mold with a structured surface can preferably be used for its production in order to specifically influence the manufacturing-related roughness in the individual surface areas of the stator component, for example, to achieve the highest possible roughness in the grooves of a cast Holweck stator or along the inner diameter of a cast spacer ring of a turbopump stage through the local surface structure of the mold in the corresponding areas.

[0038] If a sintering process is used in the primary forming process, the stator component used in the vacuum pump according to the invention is manufactured from a powdery or granular material by applying a forming and sintering process. Here, the powder or granules serving as raw material are first compacted under pressure in a mold to form a green body. This unsintered compact does not yet possess any significant strength. Therefore, subsequent sintering is necessary to obtain a stator component suitable for vacuum applications. This consists of heat treatment under a protective gas (e.g., nitrogen, hydrogen) at a relatively high temperature, is predominantly a solid-state reaction, possibly in the presence of a small amount of liquid phase, and results in thermally activated mass transport. The result of sintering is the bonding of the individual material particles to form a cohesive sintered component with high strength.The pressing and sintering processes can be repeated if necessary, for example to achieve additional densification. If a high residual porosity (e.g., >12% by volume) remains in the stator component after sintering, this pore space can be filled in a further step with a molten material (e.g., a metal or alloy) that has a lower melting point than the sintered body.

[0039] The term additive manufacturing (also referred to as "3D printing") encompasses various primary forming techniques, all of which share the common feature that the manufacturing or shaping process involves the joining of volume elements, particularly layers. However, the production of the stator component used in the vacuum pump according to the invention is not limited to a specific type of additive manufacturing. Examples of variants usable in the present invention include: powder bed fusion (PBF), in particular laser sintering, laser melting, or electron beam melting; direct metal deposition (DMD); and direct energy deposition (DED).

[0040] Additive manufacturing processes can also encompass methods in which, starting with a mixture of a material powder (e.g., ceramic or metal) and a binder (e.g., polymer, wax, or adhesive), the actual additive manufacturing process produces only a green body, which is then transformed into the final product through post-treatment, such as conventional high-temperature treatment like debinding and sintering. The green body of a stator component used in the vacuum pump according to the invention can therefore be produced, for example, by extruding a material powder-binder mixture layer by layer (fused deposition modeling, FDM) or by so-called "binder jetting," in which a component is built up by applying a binder through a nozzle onto a layer of material powder.

[0041] If the stator component used in the vacuum pump of the present invention is manufactured by an additive manufacturing process, at least one powder material is preferably used for its production. The powder material can be solidified layer by layer by physical, in particular thermal, and / or chemical processes. The powder material can be shaped and compacted, resulting in at least an approximately homogeneous material. By building the component from a powder material, it can be manufactured near-net-shape or at least substantially true to the net-shape using an additive manufacturing process, which makes it possible to produce even complex components cost-effectively, with low material consumption and minimal waste.

[0042] The aforementioned specific casting processes, sintering processes and additive manufacturing processes are merely examples and do not constitute an exhaustive list of the casting, sintering and additive processes that may be used in the present invention.

[0043] In principle, any material that meets the vacuum technology requirements can be used to manufacture the stator component used in the vacuum pump according to the invention. For example, a metallic material, a ceramic material, a metal matrix composite (MMC), a plastic, or a plastic composite material can be used.

[0044] Metallic materials and metal matrix composites are preferred because, in addition to favorable mechanical properties and good machinability, they exhibit particularly high thermal conductivity, which has a beneficial effect on heat transfer from the stator component to the adjacent housing components. Examples of metals and alloys suitable as metallic materials include aluminum, aluminum alloys, iron alloys (e.g., steel or cast iron), titanium, titanium alloys, nickel, nickel alloys, magnesium alloys, copper, copper alloys, and cobalt alloys. If the stator component of the present invention is manufactured from a metallic material, aluminum, aluminum alloys, titanium, titanium alloys, or iron alloys are preferably used, with aluminum, aluminum alloys, or iron alloys being particularly preferred, and aluminum or aluminum alloys being most preferred.

[0045] In a preferred embodiment, the stator component is formed from a metallic material, in particular aluminium or an aluminium alloy, wherein the second part of the surface of the stator component has a roughness of 30 µm to 150 µm and an emissivity of 0.7 or more.

[0046] Metal matrix composites consist of a continuous matrix of a metal or alloy in which particles or fibers of a non-metallic material are discontinuously distributed. The non-metallic material distributed in the metal matrix is ​​an inorganic material, for example, a ceramic material (e.g., a carbide, oxide, nitride, or boride) or an elemental non-metal or metalloid (e.g., carbon, silicon). When the stator component of the present invention is manufactured from a metal matrix composite, the metal or alloy that forms the matrix is ​​referred to as...The metal matrix, preferably aluminum, an aluminum alloy, an iron alloy (e.g., steel or cast iron), titanium, a titanium alloy, nickel, a nickel alloy, a magnesium alloy, copper, a copper alloy, or a cobalt alloy, is used. Particularly preferably aluminum, an aluminum alloy, an iron alloy, titanium, a titanium alloy, a magnesium alloy, copper, or a copper alloy. Even more preferably aluminum, an aluminum alloy, titanium, a titanium alloy, or a magnesium alloy. Most preferably aluminum, an aluminum alloy, titanium, or a titanium alloy. A ceramic material, which may be oxide or non-oxide, can be used as the non-metallic material. Examples of preferred oxide ceramic materials are aluminum oxide and zirconium oxide. In particular, the ceramic material is non-oxide.Non-oxide ceramics, such as nitrides, carbides, or borides, offer several advantages, including high chemical and thermal stability and superior thermal conductivity compared to oxide ceramics. Particularly preferred non-oxide ceramics are the carbides, nitrides, silicides, or borides of aluminum, hafnium, lanthanum, molybdenum, tantalum, titanium, tungsten, zirconium, (in the case of carbides, nitrides, and silicides) boron, or (in the case of carbides, nitrides, and borides) silicon. Examples of preferred non-oxide ceramic materials include boron carbide, boron nitride, boron silicide (silicon boride), lanthanum hexaboride, molybdenum silicide, silicon carbide, silicon nitride, titanium boride, titanium carbide, titanium nitride, tungsten carbide, zirconium boride, and mixtures of two or more of the same. Boron carbide, silicon carbide, silicon nitride, titanium carbide, and mixtures of two or more of the same are preferred. Silicon carbide and silicon nitride are the most preferred materials.

[0047] In addition to the elemental nonmetals already mentioned above, such as Si or C, and the ceramic materials described above, other inorganic substances can also be used as non-metallic materials in the metal matrix composite, either alternatively or additionally. For example, metal oxides that are not among the common oxide ceramic materials can also be used, namely preferably chromium oxide, iron oxide, cobalt oxide, manganese oxide, nickel oxide and / or titanium oxide, more preferably chromium oxide, iron oxide, manganese oxide and / or nickel oxide, even more preferably iron oxide and / or nickel oxide, and particularly preferably iron oxide.

[0048] The incorporation of the non-metallic material into the metal matrix can preferably be carried out as preferably indicated below for the incorporation of coloring, non-metallic inorganic agents into a metallic material.

[0049] Different material combinations can also be incorporated into the stator component. For example, one area of ​​the component can be made of one material, while another area is made of a different material. A first area of ​​the component can be made of a first metal, e.g., aluminum, and a second area of ​​the component can be made of a second metal, e.g., titanium, whereby transitions between the first and second metals, e.g., aluminum-titanium transitions, with intermetallic bonding can form in the boundary region between the two areas.

[0050] If the material from which the stator component is formed is to have a color, this can preferably be achieved by adding at least one coloring agent to the material before the formation of a near-net-shape or true-to-net-shape form, in particular before the start of the primary forming process. The presence of this coloring agent causes the material to be discolored. Here, the term "coloring agent" is intended to refer both to dyes in the narrower sense, i.e., substances that are colored themselves, and to substances that only produce a color when in contact with the material.

[0051] The coloring of the stator component's surface by a coloring agent, as described in the present invention, need not necessarily result in an optically perceptible color impression, i.e., changes in the emission spectrum in the visible range (λ = 0.38 to 0.78 µm), but can also simply increase the absorption and emission capacity for infrared radiation. Infrared radiation is defined in particular as electromagnetic radiation with wavelengths between 0.78 µm and 1 mm. In the relevant temperature range (rotor temperatures up to approximately 110°C), virtually all thermal radiation is emitted in the infrared range. Nevertheless, it is of course possible that the coloring may also be visible to the naked eye, e.g., as a gray or black discoloration of the material.

[0052] The at least one coloring agent is a non-metallic inorganic substance that can withstand the stresses of the stator component's manufacturing process and does not impair the vacuum-operated suitability of the colored stator component, e.g., with regard to mechanical and thermal stability. Preferably, at least one elemental non-metal and / or at least one inorganic pigment and / or at least one ceramic material can be used as the coloring agent; more preferably, at least one ceramic material and / or at least one inorganic pigment. The ceramic material can be oxide or non-oxide. Examples of preferred oxide ceramic materials are aluminum oxide and zirconium oxide. In particular, the ceramic material is non-oxide. As mentioned above, non-oxide ceramics, such as nitrides, carbides, or borides, offer advantages compared to oxide ceramics.Preferably, those non-oxide ceramics can be used which have already been generally described as preferred in connection with metal matrix composites above.

[0053] For example, at least one metal oxide can be used as an inorganic pigment, preferably chromium oxide, iron oxide, cobalt oxide, manganese oxide, nickel oxide and / or titanium oxide, more preferably chromium oxide, iron oxide, manganese oxide and / or nickel oxide, even more preferably iron oxide and / or nickel oxide, particularly preferably iron oxide.

[0054] The coloring agent, a non-metallic inorganic material, in particular the at least one elemental non-metal, the at least one inorganic pigment, and / or the at least one ceramic material, is preferably incorporated into a metallic material, i.e., a metal or an alloy. The primary forming processes mentioned above, such as casting, sintering, or additive manufacturing, can preferably be used for this purpose. If the stator component is a casting, it is therefore preferably produced from a mixed casting compound that contains at least one liquefied metal and at least one coloring agent dispersed therein. This can be achieved in particular by stir casting.If the stator component is a sintered part, preferably the corresponding green body is pressed from a mixture of at least one metal powder or granules with a powder or granules containing at least one coloring agent, and / or a porous sintered body obtained after sintering, containing at least one coloring agent, is infiltrated with at least one molten metallic material. If the stator component is manufactured by an additive process, it is preferred that a powder or granules of at least one metallic material are mixed with a powder or granules containing at least one coloring agent and subjected to an additive process suitable for processing metal powders, such as laser sintering, laser melting, electron beam melting, direct metal powder spraying, or direct energy deposition.

[0055] The metallic material into which the at least one coloring agent can be incorporated according to the preferred methods mentioned above is preferably one of the metallic materials that have already been generally referred to above as preferred metal matrices in connection with metal matrix composites.

[0056] Typical emissivity values ​​of metals (provided the surface is not heavily oxidized or roughened) are in the range of ε ≈ 0.1–0.4, and significantly lower for polished surfaces. Non-metallic materials, on the other hand, can exhibit considerably higher thermal emissivity values ​​than metals, typically ε ≥ 0.6. Therefore, embedding non-metallic colorants in a metallic matrix allows the emissivity of the resulting composite material to be significantly increased compared to the purely metallic material, without sacrificing the advantages of the metal or alloy, such as favorable mechanical properties, good machinability, or high thermal conductivity.

[0057] Embedding a suitable colorant in the material offers the advantage that no post-treatment of the stator component's surfaces is necessary to increase the emissivity, as the material already exhibits the color immediately after initial forming, i.e., in its untreated state. Another important advantage is that an increase in emissivity can be achieved regardless of the surface roughness. This means that even on contact, mating, or dimensioned surfaces that have undergone machining, such as subtractive machining, an increased emissivity can be realized.Furthermore, it is possible to combine the two aforementioned possibilities for increasing the emissivity within a stator component, i.e., to manufacture a stator component from a material into which a coloring agent is incorporated, and additionally to leave those surfaces that are not contact, fitting or dimension surfaces in a state with manufacturing-related high roughness.

[0058] The object of the invention is also achieved by a method according to independent claim 8. This relates to a method for manufacturing a stator component for a stator of a vacuum pump, in particular a turbomolecular pump, which has a housing and at least one pump stage arranged in the housing, comprising the stator and a rotor rotating about an axis of rotation relative to the stator during operation and interacting with the stator to provide a pumping effect, wherein the stator component has a surface comprising a first portion and a second portion different from the first portion, wherein in the method the stator component is manufactured by primary forming, in particular casting, sintering or an additive process, and wherein the first portion of the surface is subsequently subjected to post-processing by cutting, in particular machining, wherein the primary forming gives the surface of the stator component a roughness,which is in the range of 3 µm or more, preferably 5 µm or more, more preferably 10 µm or more, expressed as average,

[0059] Roughness depth Rz according to DIN EN ISO 4287:2010-07, and where the second part of the surface is left unworked.

[0060] Through primary forming, the surface of the stator component (and / or, in an unclaimed embodiment, the second part of the surface through post-processing) acquires a roughness in the range of 3 µm or more, preferably 5 µm or more, more preferably 10 µm or more, even more preferably 20 µm or more, particularly preferably 30 µm, most preferably 40 µm or more, and most preferably 50 µm or more, which brings with it the advantages already mentioned above. As explained above, the post-processing of the second part, which may be carried out in an unclaimed embodiment, can be post-processing by cutting, in particular by machining.However, it is preferred that the roughness of the second part of the surface does not fall below a value of 3 µm, more preferably 5 µm, even more preferably 10 µm, particularly preferably 20 µm, very preferably 30 µm, even more preferably 40 µm, and most preferably 50 µm, after post-processing. As explained above, in an unclaimed embodiment, the second part of the surface can also be post-treated in a way that increases its roughness. Such roughening of the second part of the surface can be achieved, for example, by removing a support structure, laser structuring, grinding, or sandblasting, preferably by removing a support structure or laser structuring, and particularly preferably by laser structuring, wherein removing a support structure is defined as described above.

[0061] In an unclaimed embodiment, the second part of the surface of an aluminum stator component is treated by laser structuring, resulting in a roughness of 65 µm and an emissivity of 0.8.

[0062] Alternatively, the problem of the invention can also be solved by a method according to independent claim 11 directed thereto.This relates to a method for manufacturing a stator component for a stator of a vacuum pump, in particular a turbomolecular pump, which has a housing and at least one pump stage arranged in the housing, comprising the stator and a rotor rotating relative to the stator about an axis of rotation during operation and interacting with the stator to effectively pump, wherein the stator component has a surface having a first part and a second part different from the first part, wherein in the method the second part of the surface is provided with a coloring by adding at least one non-metallic inorganic coloring agent to at least one starting material used in the manufacture of the stator component, i.e. a metal or an alloy, wherein the stator component is a Holweck stator of a Holweck pump stage or a spacer ring of a turbopump stage.

[0063] The stator component is preferably manufactured using a casting process, a sintering process or an additive manufacturing process, which brings with it the advantages already mentioned above.

[0064] In each of the aforementioned methods according to the invention, it is also preferred that the first part of the surface is at least partially worked to form a contact, fitting or dimensioning surface relative to one or more other components of the vacuum pump, which brings with it the advantages already mentioned above.

[0065] In each of the aforementioned methods according to the invention, it is also preferred if the manufactured stator component is a Holweck stator of a Holweck pump stage or a spacer ring of a turbopump stage.

[0066] It is understood that the methods described herein can also be further developed in accordance with the embodiments and individual features described with regard to the devices, and vice versa.

[0067] The invention is described below by way of example with reference to advantageous embodiments and the accompanying figures. These show, schematically: Fig. 1 a perspective view of a turbomolecular pump, Fig. 2 a view of the underside of the turbomolecular pump of Fig. 1 , Fig. 3 a cross-section of the turbomolecular pump along the in Fig. 2 Section line AA shown, Fig. 4 a cross-sectional view of the turbomolecular pump along the in Fig. 2 Section line BB, Fig. 5 shows a cross-sectional view of the turbomolecular pump along the line shown in Fig. 2 Section line CC shown, Fig. 6, is a comparison of cross-sectional views of a conventional Holweck system ( Fig. 6A ) and a Holweck system that provides stator surfaces with increased emissivity ( Fig. 6B) exhibits, Fig. 7 a cross-sectional view of a Holweck area with Holweck stator sleeves, whose grooves have a manufacturing-related rough surface, Fig. 8 a detailed view of a section of the Holweck area of Fig. 7 Fig. 9 shows a cross-sectional view of turbopump stages with spacer rings whose inner diameter has a rough surface due to the manufacturing process; Fig. 10 shows a detailed view of a section of a turbopump stage. Fig. 9 , Fig. 11 a cross-sectional view of a Holweck area in which an inner Holweck rotor sleeve is separated from the motor compartment of the pump by a wall with increased thermal emissivity.

[0068] The in Fig. 1The turbomolecular pump 111 shown comprises a pump inlet 115 surrounded by an inlet flange 113, to which a receiver (not shown) can be connected in a manner known per se. The gas from the receiver can be drawn out of the receiver via the pump inlet 115 and conveyed through the pump to a pump outlet 117, to which a backing pump, such as a rotary vane pump, can be connected.

[0069] The inlet flange 113 forms a Fig. 1 The upper end of the housing 119 of the vacuum pump 111. The housing 119 comprises a lower part 121, to which an electronics housing 123 is attached laterally. The electronics housing 123 contains electrical and / or electronic components of the vacuum pump 111, e.g., for operating an electric motor 125 located in the vacuum pump (see also Fig. 3The electronics housing 123 has several connections 127 for accessories. In addition, a data interface 129, e.g. according to the RS485 standard, and a power supply connection 131 are located on the electronics housing 123.

[0070] There are also turbomolecular pumps that do not have such an attached electronics housing, but are connected to external drive electronics.

[0071] The housing 119 of the turbomolecular pump 111 has a flood inlet 133, in particular in the form of a flood valve, through which the vacuum pump 111 can be flooded. In the area of ​​the lower part 121, a purge gas connection 135, also referred to as a purge gas connection, is also arranged, through which purge gas can be supplied to protect the electric motor 125 (see e.g. Fig. 3The gas pumped by the pump can be introduced into the motor compartment 137, in which the electric motor 125 is housed in the vacuum pump 111. Two coolant connections 139 are also arranged in the lower part 121, one of which serves as an inlet and the other as an outlet for coolant that can be directed into the vacuum pump for cooling purposes. Other existing turbomolecular vacuum pumps (not shown) are operated exclusively with air cooling.

[0072] The lower side 141 of the vacuum pump can serve as a base, allowing the vacuum pump 111 to be operated standing upright on its underside 141. Alternatively, the vacuum pump 111 can be attached to a receiver via the inlet flange 113 and thus operated in a suspended position. Furthermore, the vacuum pump 111 can be designed to operate even when oriented differently than described. Fig. 1 As shown. It is also possible to implement embodiments of the vacuum pump in which the underside 141 can be arranged facing sideways or upwards instead of downwards. In principle, any angle is possible.

[0073] Other existing turbomolecular vacuum pumps (not shown), which are particularly larger than the pump shown here, cannot be operated in a standing position.

[0074] On the underside 141, which is in Fig. 2As shown, various screws 143 are arranged, by means of which components of the vacuum pump, not further specified here, are fastened to one another. For example, a bearing cover 145 is attached to the underside 141.

[0075] Mounting holes 147 are also arranged on the underside 141, via which the pump 111 can be attached to a support surface, for example. This is not possible with other existing turbomolecular vacuum pumps (not shown), which are particularly larger than the pump shown here.

[0076] In the Figs. 2 to 5 A coolant line 148 is shown, in which the coolant introduced and removed via the coolant connections 139 can circulate.

[0077] Like the sectional views of the Figs. 3 to 5 As shown, the vacuum pump comprises several process gas pumping stages for conveying the process gas present at the pump inlet 115 to the pump outlet 117.

[0078] A rotor 149 is arranged in the housing 119, which has a rotor shaft 153 rotatable about a rotation axis 151.

[0079] The turbomolecular pump 111 comprises several turbomolecular pump stages connected in series to provide pumping action. These stages have several radial rotor disks 155 attached to the rotor shaft 153 and stator disks 157 arranged between the rotor disks 155 and fixed in the housing 119. Each rotor disk 155 and an adjacent stator disk 157 form a turbomolecular pump stage. The stator disks 157 are held at a desired axial distance from each other by spacer rings 159.

[0080] The vacuum pump also includes Holweck pump stages arranged radially within one another and connected in series to effectively pump the pump. Other turbomolecular vacuum pumps exist (not shown) that do not have Holweck pump stages.

[0081] The rotor of the Holweck pump stages comprises a rotor hub 161 arranged on the rotor shaft 153 and two cylindrical Holweck rotor sleeves 163, 165 attached to and supported by the rotor hub 161, which are oriented coaxially to the axis of rotation 151 and are nested inside one another in a radial direction.

[0082] Furthermore, two cylindrical Holweck stator sleeves 167, 169 are provided, which are also oriented coaxially to the axis of rotation 151 and are nested inside each other in the radial direction.

[0083] The pump-active surfaces of the Holweck pump stages are formed by the outer surfaces, i.e., the radial inner and / or outer surfaces, of the Holweck rotor sleeves 163, 165 and the Holweck stator sleeves 167, 169. The radial inner surface of the outer Holweck stator sleeve 167 faces the radial outer surface of the outer Holweck rotor sleeve 163, forming a radial Holweck gap 171, and together they form the first Holweck pump stage following the turbomolecular pumps. The radial inner surface of the outer Holweck rotor sleeve 163 faces the radial outer surface of the inner Holweck stator sleeve 169, forming a radial Holweck gap 173, and together they form a second Holweck pump stage. The radial inner surface of the inner Holweck stator sleeve 169 lies opposite the radial outer surface of the inner Holweck rotor sleeve 165, forming a radial Holweck gap 175, and together they form the third Holweck pumping stage.

[0084] At the lower end of the Holweck rotor sleeve 163, a radially extending channel can be provided, through which the radially outer Holweck slot 171 is connected to the central Holweck slot 173. Furthermore, a radially extending channel can be provided at the upper end of the inner Holweck stator sleeve 169, through which the central Holweck slot 173 is connected to the radially inner Holweck slot 175. This connects the nested Holweck pump stages in series. A connecting channel 179 to the outlet 117 can also be provided at the lower end of the radially inner Holweck rotor sleeve 165.

[0085] The aforementioned pump-active surfaces of the Holweck stator sleeves 167, 169 each have several Holweck grooves spiraling around the axis of rotation 151 in the axial direction, while the opposite outer surfaces of the Holweck rotor sleeves 163, 165 are smooth and drive the gas forward in the Holweck grooves for the operation of the vacuum pump 111.

[0086] For the rotatable mounting of the rotor shaft 153, a rolling bearing 181 is provided in the area of ​​the pump outlet 117 and a permanent magnet bearing 183 is provided in the area of ​​the pump inlet 115.

[0087] In the area of ​​the rolling bearing 181, a conical injection nut 185 with an outer diameter increasing towards the rolling bearing 181 is provided on the rotor shaft 153. The injection nut 185 is in sliding contact with at least one wiper of a fluid reservoir. In other existing turbomolecular vacuum pumps (not shown), an injection screw may be provided instead of an injection nut. Since different designs are thus possible, the term "injection tip" is also used in this context.

[0088] The operating fluid reservoir comprises several stacked absorbent discs 187, which are impregnated with an operating fluid for the rolling bearing 181, e.g. with a lubricant.

[0089] During operation of the vacuum pump 111, the operating fluid is transferred by capillary action from the fluid reservoir via the wiper to the rotating injection nut 185 and, as a result of centrifugal force, is conveyed along the injection nut 185 in the direction of the increasing outer diameter of the injection nut 185 towards the rolling bearing 181, where it performs, for example, a lubricating function. The rolling bearing 181 and the fluid reservoir are enclosed in the vacuum pump by a trough-shaped insert 189 and the bearing cover 145.

[0090] The permanent magnet bearing 183 comprises a rotor-side bearing half 191 and a stator-side bearing half 193, each containing a ring stack of several axially stacked permanent magnet rings 195, 197. The ring magnets 195, 197 face each other, forming a radial bearing gap 199, with the rotor-side ring magnets 195 arranged radially outside and the stator-side ring magnets 197 radially inside. The magnetic field present in the bearing gap 199 induces magnetic repulsion forces between the ring magnets 195, 197, which result in the radial support of the rotor shaft 153. The rotor-side ring magnets 195 are supported by a support section 201 of the rotor shaft 153, which radially surrounds the ring magnets 195 on the outside.The stator-side ring magnets 197 are supported by a stator-side support section 203, which extends through the ring magnets 197 and is suspended from radial struts 205 of the housing 119. Parallel to the axis of rotation 151, the rotor-side ring magnets 195 are fixed by a cover element 207 coupled to the support section 201. The stator-side ring magnets 197 are fixed parallel to the axis of rotation 151 in one direction by a retaining ring 209 connected to the support section 203 and a retaining ring 211 also connected to the support section 203. A disc spring 213 may also be provided between the retaining ring 211 and the ring magnets 197.

[0091] Within the magnetic bearing, an emergency or catch bearing 215 is provided, which runs freely without contact during normal operation of the vacuum pump 111 and only engages when there is excessive radial deflection of the rotor 149 relative to the stator, in order to form a radial stop for the rotor 149 and thus prevent a collision between the rotor-side and stator-side structures. The catch bearing 215 is designed as an unlubricated rolling bearing and forms a radial gap with the rotor 149 and / or the stator, which causes the catch bearing 215 to be disengaged during normal pump operation. The radial deflection at which the catch bearing 215 engages is dimensioned to be large enough so that the catch bearing 215 does not engage during normal operation of the vacuum pump, and simultaneously small enough to prevent a collision between the rotor-side and stator-side structures under all circumstances.

[0092] The vacuum pump 111 comprises the electric motor 125 for rotating the rotor 149. The armature of the electric motor 125 is formed by the rotor 149, whose rotor shaft 153 extends through the motor stator 217. A permanent magnet arrangement can be arranged radially on the outside or embedded in the section of the rotor shaft 153 extending through the motor stator 217. A space 219 is arranged between the motor stator 217 and the section of the rotor 149 extending through the motor stator 217. This space comprises a radial motor gap through which the motor stator 217 and the permanent magnet arrangement can magnetically influence each other to transmit the drive torque.

[0093] The motor stator 217 is fixed in the housing within the motor compartment 137 provided for the electric motor 125. A purge gas, also known as a sealing gas, which can be, for example, air or nitrogen, can enter the motor compartment 137 via the purge gas connection 135. This purge gas protects the electric motor 125 from process gas, e.g., from corrosive components of the process gas. The motor compartment 137 can also be evacuated via the pump outlet 117, meaning that the vacuum pressure in the motor compartment 137 is at least approximately equal to that produced by the backing pump connected to the pump outlet 117.

[0094] Between the rotor hub 161 and a wall 221 bounding the engine compartment 137, a so-called labyrinth seal 223, which is known per se, can also be provided, in particular to achieve a better seal of the engine compartment 217 against the radially outside Holweck pump stages.

[0095] The pump described above is equipped with at least one stator component according to the invention, which interacts effectively with a rotor in a pumping stage and which has the features specified in one of the independent claims, in particular in a Holweck stator of a Holweck pumping stage and / or in a spacer ring of a turbomolecular stage. Advantageously, the pump can be equipped with several stator components according to the invention, in particular several Holweck stators in Holweck pumping stages and / or several spacer rings in turbopump stages. Particularly advantageous are all stator components that interact effectively with a rotor in pumping stages, in particular all Holweck stators of all Holweck pumping stages and / or all spacer rings of all turbomolecular stages of the pump described above, which are stator components designed according to the invention.

[0096] The Figs. 6a and 6bFigure 1 shows a comparison of schematic cross-sectional views of two differently designed Holweck systems. The rotor hubs 61 arranged on the rotor shafts 53 rotating about an axis 51 during operation, and the cylindrical Holweck rotor sleeves 63, 65 attached to the rotor hubs 61 and nested radially within one another, are found in the Holweck systems of Fig. 6a and Fig. 6b They are the same and can each be formed in the conventional manner. However, the cylindrical Holweck stator sleeves 67, 69 and 68, 70, which are also nested inside each other in the radial direction, differ from one another.

[0097] The in Fig. 6a The system shown contains conventional Holweck stator sleeves 67, 69, which do not exhibit an increased thermal emissivity anywhere.

[0098] The in Fig. 6bThe system shown, however, contains Holweck stator sleeves 68, 70 according to the present invention, whose dotted surfaces have a higher thermal emissivity compared to conventional sleeves 67, 69 and thus result in improved heat dissipation. This applies in Fig. 6b both the radial inner and outer surfaces of the inner Holweck stator sleeve 70 and the radial inner surface of the outer Holweck stator sleeve 68.

[0099] Specifically, the surfaces with increased thermal emissivity include the surfaces of the webs 681, including those of the respective web tips 683, and the grooves 685 located between the webs 681 on the radial inner surface of the outer Holweck stator sleeve 68, as well as the surfaces of the webs 701, 702, including those of the web tips 703, 704, and the grooves 705, 706 on the radial outer surface and the radial inner surface of the inner Holweck stator sleeve 70, and those channel-side stator surfaces 721, 741, 761 which form the channels 72, 74, 76. The radially extending channel 72 connects the first Holweck gap 71 with the second Holweck gap 73 and is bounded on one side by the lower end 631 of the outer Holweck rotor sleeve 63, and on the other side by a channel-side stator surface 721.The radially extending channel 74 connects the second Holweck slot 73 with the third Holweck slot 75 and is bounded on one side by the rotor hub 61 and on the other side by the surface 741 at the upper end of the inner stator sleeve 70. The radially extending channel 76 connects the third Holweck slot 75 with an outlet (not shown) and is bounded on one side by the lower end of the inner Holweck rotor sleeve 65 and on the other side by the channel-side stator surface 761.

[0100] In the Fig. 6b In the embodiment shown, in each of the three Holweck pump stages, the stator surface opposite the rotor surface has an increased thermal emissivity in its entirety, so that increased heat transport by thermal radiation from the rotor to the stator takes place over the entire Holweck gap 71, 73, 75.

[0101] As also from the Fig. 6bAs can be seen, the outer surface 689 of the outer stator sleeve 68 does not exhibit an increased thermal emissivity. Such an emissivity is not required at this point, since the outer surface 689 serves to fit into the (not shown) pump housing. Therefore, in the operating state of the pump, there is no gap through which heat transfer via radiation would have to occur; instead, the heat transfer takes place directly from the outer surface 689 to a housing part (not shown) immediately adjacent to it.

[0102] It is understood that other embodiments are also possible within the scope of the invention, which differ from the one described in Fig. 6b The schematically shown configuration of the Holweck system may differ. In particular, it is possible that not all stator surfaces shown in Fig. 6b are shown as dotted lines, but only a portion of these areas exhibits an increased thermal emissivity.

[0103] For example, it can be advantageous if—in addition to the contact surfaces of the stator component with other pump components—the web tips 681, 701, 704 and / or the channel-side Holweck stator surfaces 721, 741, 761 are not designed with an increased thermal emissivity, either entirely or partially. This is particularly useful if the increased thermal emissivity is to be achieved through high roughness, which could be detrimental to the high dimensional accuracy required to form a narrow Holweck gap 71, 73, 75 or channel 72, 74, 76 between the rotor and stator. The increase in thermal emissivity can then be limited, in particular, to those surfaces of the stator component where the requirements for dimensional accuracy are lower, for example, the surfaces of the grooves 685, 705, 706 of the Holweck stator sleeves 68, 70.

[0104] The Figs. 7 and 8Figure 1 shows such an embodiment. A Holweck area of ​​a turbomolecular pump is shown, in which the grooves 685, 705, 706 of the inner and outer Holweck stator sleeves 68, 70 have a rough surface due to the manufacturing process. Fig. 8 shows an enlarged section of the Holweck area of ​​the Fig. 7 at the lower end of the Holweck stator sleeves.

[0105] The irregularities of the groove surfaces are in the Figs. 7 and 8 For better illustration, the figures are greatly exaggerated and not shown to scale. In this embodiment, only the surfaces of the grooves 685, 705, and 706 exhibit a high manufacturing-related roughness and consequently a high thermal emissivity. All other surfaces of the grooves shown in the diagram have a high surface roughness. Figs. 7 and 8The stator components shown, i.e., among others, the web tips 683, 703, 704 of the inner and outer Holweck stator sleeves 68, 70 and the contact surfaces of the stator components to other pump parts, e.g., the outer shell surface 689 of the outer Holweck stator sleeve 68, are, however, smoothed by machining in order to be able to comply with the required tolerances and to ensure good heat transfer at the contact surfaces.

[0106] However, as particularly evident from the Fig. 7As can be seen, in the Holweck stages, the vast majority of the stator surface opposite the rotor sleeves is occupied not by the web tips 683, 703, 704, but by the slots 685, 705, 706. Machining of relatively small surface areas, such as the web tips 683, 703, 704, therefore does not significantly impair the heat radiation from the rotor to the stator. The differently shaped surfaces of the Holweck stator sleeves complement each other optimally to achieve the best possible heat dissipation from the rotor to the stator (via the rough slots 685, 705, 706) and subsequently from the stator to the housing (via the smooth outer surface 689).

[0107] Fig. 9shows several turbopump stages connected in series, each consisting of a rotor disk 55 attached to the rotor shaft 53 and a stator disk 57 adjacent to it, wherein the stator disks 57 are axially spaced apart from each other by spacer rings 59. Fig. 10 shows an enlarged view of a spacer ring 59 from the Fig. 9 .

[0108] Along the inner diameter of each spacer ring 59, an inner diameter surface 591 of the spacer ring 59 faces each rotor disk 55. The distance between the radially outer ends of the rotor disks 55 and the inner diameter surfaces 591 of the spacer rings 59 is so large that, due to tolerances, it is possible to use spacer rings 59 in which the entire inner diameter surface 591 has not been machined after primary forming. The entire inner diameter surface 591 of the spacer ring 59 is therefore unmachined, resulting in a high manufacturing-related roughness and consequently a high thermal emissivity. Since this, as in Fig. 9 As shown, this applies to all spacer rings 59 used, thus maximizing heat transfer by radiation from the rotor to the stator in all turbomolecular pumping stages of the pump.

[0109] As can be seen in particular from the enlarged illustration in Fig. 10As can be seen, the contact surfaces 599 of the spacer rings 59 with adjacent spacer rings 59, stator disks 57 and the housing 19 are smoothed by machining to achieve the required fit and to ensure good heat transfer, especially to the housing. The majority of the surfaces that are directly opposite the rotor disks 55 and can thus absorb the thermal radiation emitted by them, however, are, as shown Fig. 9 The surfaces 591, which have a high emissivity, are evidently covered by surfaces 591. The differently shaped surfaces of the spacer rings 59 thus complement each other optimally to achieve the best possible heat dissipation from the rotor to the stator (via the rough inner diameter surface 591) and subsequently from the stator to the housing (via the smooth contact surface 599).

[0110] Fig. 11Figure 1 shows a further embodiment in which a wall 22 delimiting the motor compartment 37 of the pump is designed as a stator component in accordance with the present invention. The in Fig. 11 The dotted surface 23 of the wall 22, facing the inner Holweck rotor sleeve 65, has a higher thermal emissivity than a conventional wall. This results in increased heat dissipation from the rotor by radiation across the gap 24, which separates the inner Holweck rotor sleeve 65 from the wall 22.

[0111] It goes without saying that the ones in the Figs. 6 to 11 The features shown can be combined with one another as desired. It is therefore possible, for example, and quite advantageous due to the resulting improved heat dissipation, to incorporate one or more Holweck stator sleeves 68, 70 within a turbomolecular pump as shown in the Fig. 6b , 7 or 8 shown, one or more spacer rings 59 as in the Fig. 9 or 10shown, and / or one or more walls 22 as in Fig. 11 shown how to install them together and use them simultaneously. Reference symbol list

[0112] 22 Wall 23 Surface 24 Gap 37 Motor compartment 51 Rotation axis 53 Rotor shaft 55 Rotor disk 57 Stator disk 59 Spacer ring 61 Rotor hub 63 Outer Holweck rotor sleeve 65 Inner Holweck rotor sleeve 67 Outer Holweck stator sleeve 68 Outer Holweck stator sleeve 69 Inner Holweck stator sleeve 70 Inner Holweck stator sleeve 71 Holweck gap 72 Channel 73 Holweck gap 74 Channel 75 Holweck gap 76 Channel 111 Turbomolecular pump 113 Inlet flange 115 Pump inlet 117 Pump outlet 119 Housing 121 Lower part 123 Electronics housing 125 Electric motor 127 Accessory connection 129 Data interface 131 Power supply connection 133 Flood inlet 135 Sealing gas connection 137 Engine compartment 139 Coolant connection 141 Underside 143 Screw 145 Bearing cover 147 Mounting hole 148 Coolant line 149 Rotor 151 Rotation shaft 153 Rotor shaft 155 Rotor disc 157 Stator disc 159 Spacer ring 161 Rotor hub 163 Holweck rotor sleeve 165 Holweck rotor sleeve 167 Holweck stator sleeve 169 Holweck stator sleeve 171 Holweck gap 173 Holweck gap 175 Holweck gap179 Connecting channel 181 Rolling bearing 183 Permanent magnet bearing 185 Injection nut 187 Washer 189 Insert 191 Rotor-side bearing half 193 Stator-side bearing half 195 Ring magnet 197 Ring magnet 199 Bearing gap 201 Support section 203 Support section 205 Radial strut 207 Cover element 209 Support ring 211 Mounting ring 213 Disc spring 215 Emergency or catch bearing 217 Motor stator 219 Gap 221 Wall 223 Labyrinth seal 591 Inner diameter surface 681 Web 683 Web tip 685 Groove 701 Web 702 Web 703 Web tip 704 Web tip 705 Groove 706 Groove 721 Channel-side Stator surface 741, channel-side stator surface 761, channel-side stator surface

Claims

1. A vacuum pump (111), in particular a turbomolecular pump, comprising a housing (19, 119) and at least one pump stage which is arranged in the housing (19, 119) and which comprises a stator and a rotor (149) which rotates relative to the stator about an axis of rotation (51, 151) during operation and cooperates with the stator in a pump-active manner, wherein the stator comprises at least one stator component comprising a surface which has a first portion and a second portion different from the first portion, wherein the second portion of the surface has a production-related roughness which is in the range of 3 µm or more, preferably 5 µm or more, more preferably 10 µm or more, expressed as a mean roughness depth Rz according to DIN EN ISO 4287:2010-07, characterized in that the second portion of the surface is uncoated, and in that the production-related roughness of the second portion of the surface is not changed by a cutting post-processing, and in that the first portion of the surface has been subjected to a post-processing by cutting, in particular a chip-forming processing.

2. A vacuum pump (111) according to claim 1, wherein the second portion of the surface has a coloring, in particular wherein the coloring has been obtained by adding at least one coloring agent to a starting material used in the production of the stator component.

3. A vacuum pump (111) according to one of the preceding claims, wherein the stator component is a Holweck stator (68, 70, 167, 169) of a Holweck pump stage or a spacer ring (59, 159) of a turbopump stage.

4. A vacuum pump (111), in particular a turbomolecular pump, comprising a housing (19, 119) and at least one pump stage which is arranged in the housing (19, 119) and which comprises a stator and a rotor (149) which rotates relative to the stator about an axis of rotation (51, 151) during operation and cooperates with the stator in a pump-active manner, wherein the stator comprises at least one stator component comprising a surface which has a first portion and a second portion different from the first portion, wherein the second portion of the surface is uncoated, and wherein the stator component is a Holweck stator (68, 70, 167, 169) of a Holweck pump stage or a spacer ring (59, 159) of a turbopump stage, characterized in that the second portion of the surface has a coloring, wherein the coloring has been obtained by adding at least one non-metallic inorganic coloring agent to a metallic starting material used in the production of the stator component, i.e. a metal or an alloy.

5. A vacuum pump (10) according to claim 4, wherein the first portion of the surface has been subjected to a post-processing, in particular a post-processing by cutting, in particular a chip-forming processing.

6. A vacuum pump (111) according to any one of the preceding claims, wherein the first portion of the surface in the assembled state of the pump stage at least regionally forms a contact surface, a fit surface or a dimensional surface relative to one or more other components of the vacuum pump (111).

7. A vacuum pump (111) according to any one of the preceding claims, wherein the stator component is produced by a casting process, a sintering process or an additive process.

8. A method for manufacturing a stator component for a stator of a vacuum pump (111), in particular a turbomolecular pump, which comprises a housing (19, 119) and at least one pump stage which is arranged in the housing (19, 119) and which comprises the stator and a rotor (149) which rotates relative to the stator about an axis of rotation (51, 151) during operation and cooperates with the stator in a pump-active manner, wherein the stator component comprises a surface which has a first portion and a second portion different from the first portion, wherein, in the method, the stator component is produced by primary shaping, in particular by casting, sintering or an additive process, and wherein the first portion of the surface is then subjected to a post-processing by cutting, in particular a chip-forming processing, wherein, through the primary shaping, the surface of the stator component obtains a roughness which is in the range of 3 µm or more, preferably 5 µm or more, more preferably 10 µm or more, expressed as a mean roughness depth Rz according to DIN EN ISO 4287:2010-07, wherein the second portion of the surface is left untreated.

9. A method according to claim 8, wherein, in the method, the second portion of the surface is provided with a coloring, in particular by adding at least one coloring agent to at least one starting material used in the production of the stator component.

10. A method according to claim 8 or 9, wherein the stator component is a Holweck stator (68, 70, 167, 169) of a Holweck pump stage or a spacer ring (59, 159) of a turbopump stage.

11. A method for manufacturing a stator component for a stator of a vacuum pump (111), in particular a turbomolecular pump, which has a housing (19, 119) and at least one pump stage which is arranged in the housing (19, 119) and which comprises the stator and a rotor (149) which rotates relative to the stator about an axis of rotation (51, 151) during operation and cooperates with the stator in a pump-active manner, wherein the stator component comprises a surface which has a first portion and a second portion different from the first portion, wherein, in the method, the second portion of the surface is provided with a coloring by adding at least one non-metallic inorganic coloring agent to at least one metallic starting material used in the production of the stator component, i.e. a metal or an alloy, wherein the stator component is a Holweck stator (68, 70, 167, 169) of a Holweck pump stage or a spacer ring (59, 159) of a turbopump stage.

12. A method according to claim 11, wherein the stator component is manufactured by a casting process, a sintering process or an additive process.

13. A method according to any one of the claims 8 to 12, wherein the first portion of the surface is at least regionally processed into a contact surface, a fit surface or a dimensional surface relative to one or more other components of the vacuum pump (111).

14. A vacuum pump (111) according to any one of the claims 1 to 7, wherein the stator component is obtained or can be obtained by a method according to any one of the claims 8 to 13.

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