Electric machine with at least one fluid radial bearing and / or fluid axial bearing and surrounding elastic area, method for manufacturing and method for adapting the elastic area, and use of the electric machine

Abstract

The present invention relates to an electric machine in the form of an air compressor (1) with a cylindrical housing (2), wherein the housing (2) comprises at least one bearing plate (6) and a fluid bearing arrangement (8) with a rotatably mounted rotor (10) and at least one fluid radial bearing and / or fluid axial bearing (12, 12n), wherein the housing (2) and / or the at least one bearing plate (6) have at least one area of ​​reduced wall thickness (14) positioned such that an elastic zone (16) is formed around the at least one fluid radial bearing and / or fluid axial bearing (12, 12n) to compensate for vibrations. The invention further relates to a method for producing at least one area of ​​reduced wall thickness (14) and a method for adapting the elastic zone (16) to a simulated and / or measured required elasticity of the at least one fluid radial bearing and / or fluid axial bearing (12, 12n).The invention further relates to the use of the electric machine in the form of the air compressor (1) and the methods for compensating for manufacturing and / or assembly tolerances.

Description

Technical field

[0001] The present invention relates to an electric machine in the form of an air compressor with a cylindrical housing, wherein the housing comprises at least one bearing plate and a fluid bearing arrangement with a rotatably mounted rotor and at least one fluid radial bearing and / or fluid axial bearing. The housing and / or the at least one bearing plate has at least one area of ​​reduced wall thickness, which is positioned such that an elastic zone is created around the at least one fluid radial bearing and / or fluid axial bearing to compensate for vibrations. The invention further relates to a method for producing at least one area of ​​reduced wall thickness and a method for adapting the elastic zone to a simulated and / or measured required elasticity of the at least one fluid radial bearing and / or fluid axial bearing.The invention further relates to the use of the electric machine in the form of the air compressor and the methods for compensating for manufacturing and / or assembly tolerances. State of the art

[0002] DE 10 2018 201 162 A1 discloses a fuel cell system based on the principle that air is drawn in from the environment, pressurized to the necessary pressure in an air compressor, and ultimately supplied to the fuel cell stack for power generation. The air compressor comprises a stator and a rotor, the rotor being designed as a shaft with a compressor end and optionally a turbine end. The shaft is supported by at least one radial bearing, preferably by two radial bearings, which are preferably arranged at the two axial ends. In suitable air compressors, the shaft is additionally supported by at least one axial bearing.

[0003] Since high temperatures are used in such high-speed applications, and external power should be avoided as much as possible to ensure smooth operation even during power outages, the radial and axial bearings are designed as fluid bearings, also known as air bearings. In this design, the bearing between the rotor and stator consists of a thin fluid or air film. This film is able to absorb and dampen acting forces such as vibrations. Due to their low weight, air bearings are particularly well-suited for systems that are sensitive to corrosion and foreign particles, as they do not require oil, water, or other lubricants. Furthermore, as described, air bearings operate without contact, resulting in minimal abrasion and wear, which also makes them relatively low-maintenance.

[0004] However, the use of air bearings also presents the problem that they are extremely susceptible to asymmetrical external forces, such as imbalances, which can never be completely eliminated, and vibrations can only be absorbed to a certain extent. Furthermore, air bearings must be manufactured with extreme precision, as the narrow air gap allows for only minimal tolerances of approximately 10 µm. Besides the significant time investment, this also means increased manufacturing costs and, when installing such air bearings, considerable assembly effort.

[0005] CN 219420439 U discloses axial bearing discs for an air compressor, comprising an outer and an inner annular disc, the inner annular disc being located in the central recess of the outer annular disc. The inner annular disc has an axial hole in its center. Radial grooves extend from the center of the inner annular disc to where they meet the outer annular disc. The axial height of the inner annular disc is significantly greater than the height of the outer annular disc. The resulting recesses near the bearing disc fixing are intended to improve the fastening of the rotor shaft assembly.

[0006] The axial increase in the height of the inner ring disc, compared to a flatter design, requires more material, resulting in a heavier bearing disc that is detrimental to the low weight of the air bearings. Furthermore, while some flexibility can be achieved near the bearing disc's fixing point, vibrations in an air compressor also originate at other points, particularly in the housing and the attached end shields. The end shields essentially act as end caps at the first and second ends of the cylindrical housing and accommodate the rotor shaft ends. A uniform gap between the stator and rotor is crucial to compensate for movement and thermal expansion, making the end shields, and especially the connection between them and the housing, highly susceptible to external forces.

[0007] The demand for systems capable of compensating for externally acting forces on electric machines, particularly air compressors, such as vibrations and slight imbalances, is therefore immense. The aim is to create a system that provides sufficient elasticity to compensate for both axial and radial manufacturing and assembly tolerances, such as positional and / or angular tolerances. Furthermore, the system should be easy to manufacture and should not negatively impact the overall weight of the electric machine, especially the air compressor. Disclosure of the invention

[0008] According to the invention, an electric machine, in particular an air compressor, is proposed, comprising a cylindrical housing, wherein the housing includes at least one bearing plate at a first end and furthermore a fluid bearing arrangement. The fluid bearing arrangement comprises a rotatably mounted rotor and at least one fluid radial bearing and / or fluid axial bearing. The housing and / or the at least one bearing plate have at least one area of ​​reduced wall thickness, wherein the at least one area of ​​reduced wall thickness is positioned such that an elastic zone is created around the at least one fluid radial bearing and / or fluid axial bearing, designed and configured to compensate for vibrations.

[0009] An elastic region within the meaning of the invention is therefore a region that forms, in particular, in the immediate vicinity of the at least one fluid radial bearing and / or fluid axial bearing, and / or acts upon the immediate vicinity of the at least one fluid radial bearing and / or fluid axial bearing in order to mitigate and dampen vibrations that may arise in both the radial and axial directions. The vibrations need not necessarily originate locally at the at least one fluid radial bearing and / or fluid axial bearing itself, but can also develop in other areas of the electric machine, in particular the air bearing, due to external influences, and have negative effects on the at least one fluid radial bearing and / or fluid axial bearing.

[0010] According to the invention, a location of reduced wall thickness is understood to be a location where the wall thickness is reduced by up to 50%, preferably up to 70%, and particularly preferably up to 90%. Preferably, material recesses are present on both sides, but at certain locations, such as corners, edges, or bends within the electric machine, especially the air compressor, they may also be present on only one side. According to the invention, at least one such location is present on the housing and / or the at least one bearing shield; preferably, several locations of reduced wall thickness are present, which, depending on the component, can be arranged at regular intervals. Preferably, at least one location of reduced wall thickness, and preferably several such locations, are present in both the housing and the at least one bearing shield.In the case of multiple areas of reduced wall thickness, these can all exhibit the same degree of reduction, for example, all reduced by 30%. Alternatively, it is also possible that different degrees of reduction exist at the various locations, which can be the case particularly at points subjected to a certain mechanical stress, where an excessive reduction in wall thickness can be detrimental.

[0011] In preferred embodiments of the electric machine according to the invention, particularly the air compressor, the housing comprises a further bearing shield at its second end, wherein the further bearing shield has an additional area of ​​reduced wall thickness. The further bearing shield can have exactly one additional area of ​​reduced wall thickness, but preferably several such areas. A second bearing shield offers the advantage that, during repair or maintenance work, the interior of the machine, in particular the assembly around the rotor, can be accessed more easily. In suitable embodiments, a first bearing shield is attached to the drive side and the second bearing shield to the fan side.

[0012] In suitable embodiments of the electric machine according to the invention, in particular the air compressor, the at least one area of ​​reduced wall thickness exhibits a 100% reduction in wall thickness and is therefore designed as at least one cavity, which also forms the elastic region according to the invention. In cases where there are multiple areas of reduced wall thickness, all areas can be designed as multiple cavities. Alternatively, it is also possible that only individual areas are designed as cavities.

[0013] The at least one cavity, or the plurality of cavities, can in some embodiments include a closure element, in particular a plurality of closure elements, whereby even in this embodiment not all cavities necessarily have to include a closure element. The closure element serves to close the at least one cavity when locally high heat capacities and / or vibrations occur. This allows the vibration characteristics to be specifically adapted for operation. According to the invention, the closure element is designed as a cover, which is attached to the at least one cavity by welding, soldering, or bonding in such a way that a tight form fit and / or material bond is achieved.

[0014] In advantageous embodiments of the electric machine according to the invention, particularly the air compressor, the at least one cavity comprises a filler material. In the case of a plurality of cavities, each cavity can contain a filler material, or the filler material may be present only in some selected cavities. It is also possible for the cavities to each contain a different filler material. It is particularly preferred if the at least one cavity, or all cavities, filled with a filler material comprise a previously described closure element that prevents the filler material from escaping. According to the invention, the filler material can be a solid, a liquid, an emulsion, a suspension, and / or a gel. In this embodiment of the machine according to the invention, particularly the air compressor, it is advantageous to select materials for the filler that effectively dampen vibrations.The insulation is almost complete. It is important that materials are used that do not increase the overall weight of the electric machine, particularly the air compressor, and that tolerate high temperatures. Composite foam, natural rubber, silicone, glass wool, and silica fibers, for example, have proven to be particularly suitable materials. By using the filler, the vibration characteristics of the electric machine according to the invention can be adjusted even more precisely. For example, the filler is able to dampen vibrations or increase or decrease local heat capacities, so that heat flows can be manipulated in a targeted manner.

[0015] The at least one fluid radial bearing and / or fluid axial bearing comprises, in suitable embodiments, a radial bearing disc and / or axial bearing disc. It has proven advantageous if, in addition to the previously discussed areas of reduced wall thickness in the housing and / or the at least one bearing shield, the radial bearing disc and / or axial bearing disc also has at least one area of ​​reduced wall thickness. This at least one area of ​​reduced wall thickness further contributes to forming the elastic zone around the at least one fluid radial bearing and / or fluid axial bearing. In preferred embodiments, the at least one radial bearing disc and / or axial bearing disc can also have a plurality of areas of reduced wall thickness, whereby not all areas need to exhibit the same reduction in wall thickness.For areas of reduced wall thickness in the discs, a reduction in wall thickness of up to 50%, preferably up to 70% and particularly preferably up to 90%, is possible.

[0016] In the case of at least one area of ​​the disc with reduced wall thickness, it is also possible that this area exhibits a 100% reduction in wall thickness, meaning it is formed as at least one disc cavity. With multiple areas of reduced wall thickness, either all of these areas can be cavities, or alternatively, only some of them. When multiple areas of reduced wall thickness are present, it has proven advantageous for these areas to be distributed at regular intervals across the entire radial and / or axial bearing disc, particularly if the reductions in wall thickness are designed to ensure a uniform distribution and maintain the original center of gravity.

[0017] According to the invention, a method for producing at least one area of ​​reduced wall thickness, in particular a cavity, in the housing and / or the at least one bearing shield is further proposed. Alternatively or additionally, the method can also include producing a disc area of ​​reduced wall thickness, in particular a disc cavity, in the radial bearing disc and / or axial bearing disc. The method according to the invention comprises either inserting a cast core at the required locations in the housing and / or the at least one bearing shield and / or the radial bearing disc and / or axial bearing disc, or machining the housing and / or the bearing shield and / or the radial bearing disc and / or axial bearing disc at the required locations.In an alternative method according to the invention, a combination of both steps is also conceivable, i.e., both the insertion of a cast core at some of the required locations and the machining at other locations. Machining offers the advantage of extremely precise work while preserving the material's mechanical properties. Furthermore, machining requires minimal tooling and is therefore easy to automate. In contrast, casting with a core liner allows for optimal material utilization, as—unlike machining—there is very little material loss, making the use of a core liner the preferred method.

[0018] The invention also proposes a method for adapting the elastic range to a simulated and / or measured required elasticity of the at least one fluid radial bearing and / or fluid axial bearing. The method according to the invention for adapting the elastic range comprises providing at least one area of ​​reduced wall thickness, in particular a plurality of areas of reduced wall thickness, to the housing and / or the at least one bearing shield. In a suitable embodiment of the method according to the invention for adapting the elastic range, it comprises providing at least one cavity, in particular a plurality of cavities, to the housing and / or the at least one bearing shield.

[0019] Alternatively or additionally, the inventive method for adapting the elastic range to a simulated and / or measured required elasticity of the at least one fluid radial bearing and / or fluid axial bearing can also include the application of at least one disk area of ​​reduced wall thickness, in particular a plurality of disk areas of reduced wall thickness, to the radial bearing disk and / or axial bearing disk, in particular the application of at least one disk cavity, in particular a plurality of disk cavities.

[0020] In suitable embodiments, the areas or disk areas of reduced wall thickness, in particular the cavities or disk cavities, are obtained by a method according to the invention for producing at least one area of ​​reduced wall thickness, in particular a cavity.

[0021] Furthermore, the invention proposes a use of the electrical machine according to the invention, in particular the air compressor, as well as a use of the method according to the invention for producing at least one area of ​​reduced wall thickness, in particular a cavity. It also proposes a use of the method according to the invention for adapting the elastic range to a simulated and / or measured required elasticity of the at least one fluid radial bearing and / or fluid axial bearing, wherein all uses according to the invention serve to increase the compliance of the electrical machine according to the invention, in particular the air compressor, and to compensate for the manufacturing and / or assembly tolerances of the electrical machine according to the invention, in particular the air compressor.

[0022] All features and designs that have already been discussed for the electrical machine according to the invention, in particular the air compressor, can be transferred or applied analogously to the methods and uses according to the invention. Advantages of the invention

[0023] By providing at least one area of ​​reduced wall thickness in the housing and / or the at least one bearing shield in the electric machine, in particular in the air compressor, an elastic area can be created in the vicinity of the at least one fluid radial bearing and / or fluid axial bearing, which is able to mitigate and dampen radial and axial vibrations and thus compensate for them.

[0024] According to the invention, the elasticity is not only created locally in the area of ​​the at least one fluid radial bearing and / or fluid axial bearing, but, depending on the choice of positioning of the points of reduced wall thickness, can extend through the entire electrical machine, in particular the air compressor, in the housing and / or the at least one bearing shield.

[0025] This allows for increased compliance of the electric machine, particularly the air compressor, enabling greater manufacturing and / or assembly tolerances, such as positional and / or angular tolerances, when using air bearings. This can reduce manufacturing costs and assembly effort, especially for electric machines with a second end plate. It also results in a more robust electric machine with a longer service life.

[0026] In contrast to the prior art, the invention does not compromise lightweight construction, as material usage is further reduced. This is achieved through the inventive method for producing the reduced wall thickness at least at one point. The electric machine can thus be manufactured in a more resource-efficient manner, which, combined with its longer service life, also makes it more sustainable.

[0027] In embodiments of the machine according to the invention, in particular the air compressor according to the invention, in which an additional filler is used, this can help to dampen vibrations generated by external forces effectively or to almost completely isolate them.

[0028] The elastic area can also be further created or optimized by at least one point of reduced wall thickness in the radial bearing disc and / or axial bearing disc. Brief description of the drawings

[0029] Embodiments of the invention are explained in more detail with reference to the drawings and the following description.

[0030] They show: Fig. 1 a schematic perspective view and a schematic cross-sectional view of an electrical machine, in particular an air compressor; Fig. 2 a section of a schematic cross-sectional view of an electrical machine according to the invention, in particular an air compressor; Fig. 3 a further section of a schematic cross-sectional view of an electrical machine according to the invention, in particular an air compressor, and Fig. 4 a schematic top view of the first end of an electrical machine according to the invention, in particular an air compressor. Embodiments of the invention

[0031] In the following description of embodiments of the invention, identical or similar elements are designated by the same reference numerals, and repeated descriptions of these elements are omitted in individual cases. The figures represent the subject matter of the invention only schematically.

[0032] Fig. Figure 1 shows a perspective view on the left and a cross-sectional view on the right of an electric machine, in particular an air compressor 1. The electric machine, in particular the air compressor 1, comprises a cylindrical housing 2 with a bearing shield 6 at the first end 4. Inside the housing 2 is a fluid bearing arrangement 8, which has a rotatably mounted rotor 10 and, in the case of the embodiment shown, two fluid radial bearings 12, 12'.

[0033] Fig. Figure 2 shows a section of a schematic cross-sectional view of an electric machine according to the invention, in particular an air compressor 1. In the embodiment on the left side, the housing 2 has a location of reduced wall thickness 14, wherein this location of reduced wall thickness 14 is positioned such that, in the embodiment shown here, an elastic area 16 is created which extends to the area of ​​the two fluid radial bearings 12, 12' (see Figure 2). Fig. 1) has an effect and is designed and set up to compensate for vibrations (not shown).

[0034] The embodiment on the right side differs from that on the left side in that the wall thickness is reduced by 100%, and the housing 2 therefore has a cavity 22 which also forms an elastic area 16.

[0035] Fig. Figure 3 shows alternative configurations to the embodiments according to Fig. 2.

[0036] On the left side, the one already in Fig. 2 Cavity 22 shown in the housing 2 additionally a locking element 24.

[0037] In the embodiment on the right side, the cavity 22 is additionally filled with a filler 26, wherein the closure element 24 prevents the filler 26 from escaping from the cavity 22.

[0038] Fig. Figure 4 shows a schematic top view of the first end 4 of an electric machine according to the invention, in particular an air compressor 1. In the embodiment shown, the bearing shield 6 is shown, wherein this has a cavity 22 which is positioned such that an elastic area 16 is created which extends to the area of ​​the two fluid radial bearings 12, 12' (see Figure 4). Fig. 1) has an effect and is designed and set up to compensate for vibrations (not shown).

[0039] The embodiment on the right shows, indicatedly, a plurality of cavities 22, 22', ...22n in the bearing shield 6, wherein these are formed at regular intervals from each other and extend circularly over the bearing shield 6 (indicated).

[0040] The invention is not limited to the embodiments described here and the aspects highlighted therein. Rather, within the scope specified by the claims, a multitude of modifications are possible that fall within the bounds of what is considered skilled in the art. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2018 201 162 A1

[0002] CN 219420439

[0005]

Claims

[1] Electric machine, in particular air compressor (1), comprising a cylindrical housing (2), wherein the housing (2) comprises at least one bearing shield (6) at a first end (4), wherein the housing (2) further comprises a fluid bearing arrangement (8), wherein the fluid bearing arrangement (8) comprises a rotatably mounted rotor (10) and at least one fluid radial bearing and / or fluid axial bearing (12, 12n), wherein the housing (2) and / or the at least one bearing shield (6) have at least one location of reduced wall thickness (14), wherein the at least one location of reduced wall thickness (14) is positioned such that an elastic zone (16) is formed around the fluid radial bearing and / or fluid axial bearing (12, 12n), designed and configured to compensate for vibrations. [2] Electric machine, in particular air compressor (1), according to claim 1, wherein the housing (2) comprises a further bearing shield (20) at its second end (18), wherein the further bearing shield (20) has a further point of reduced wall thickness (14'). [3] Electric machine, in particular air compressor (1), according to claim 1 or 2, wherein the at least one location of reduced wall thickness (14) is designed as at least one cavity (22), in particular wherein a plurality of locations of reduced wall thickness (14, 14n) is designed as a plurality of cavities (22, 22n), designed and configured to form the elastic region (16). [4] Electric machine, in particular air compressor (1), according to claim 3, wherein the at least one cavity (22), in particular the plurality of cavities (22, 22n), comprises a closing element (24), in particular a plurality of closing elements (24, 24n), wherein the at least one closing element (24) is designed and configured to close the at least one cavity (22) when locally high heat capacities and / or vibrations occur. [5] Electric machine, in particular air compressor (1), according to at least one of claims 3 or 4, wherein the at least one cavity (22), in particular the plurality of cavities (22, 22n), comprises a filler (26), in particular wherein the filler (26) is prevented from escaping by the closure element (24) according to claim 4, wherein the filler (26) comprises a solid, a liquid, an emulsion, a suspension and / or a gel. [6] Electric machine, in particular air compressor (1), according to at least one of the preceding claims, wherein the at least one fluid radial bearing and / or fluid axial bearing (12, 12n) comprises a radial bearing disk and / or axial bearing disk (28, 28'), wherein the radial bearing disk and / or axial bearing disk (28, 28') has at least one disk area of ​​reduced wall thickness (30), in particular a plurality of disk areas of reduced wall thickness (30, 30n), wherein the disk area of ​​reduced wall thickness (30) is designed and configured to additionally form the elastic region (16). [7] Electric machine, in particular air compressor (1), according to claim 6, wherein the at least one disk location of reduced wall thickness (30) is designed as at least one disk cavity (32), in particular wherein a plurality of disk locations of reduced wall thickness (30, 30n) is designed as a plurality of disk cavities (32, 32n). [8] Method for producing a location of reduced wall thickness (14), in particular a cavity (22), in which housing (2) and / or the at least one bearing shield (6, 20), and / or comprising a disc area of ​​reduced wall thickness (30), in particular a disc cavity (32), in the radial bearing disc and / or axial bearing disc (28, 28') Insertion of a cast core at the required locations in the housing (2) and / or the at least one bearing shield (6, 20) and / or the radial bearing washer and / or axial bearing washer (28, 28') and / or Machining of the housing (2) and / or of the at least one bearing shield (6, 20) and / or of the radial bearing disc and / or axial bearing disc (28, 28') at the required locations. [9] Method for adapting the elastic range (16) to a simulated and / or measured required elasticity of the at least one fluid radial bearing and / or fluid axial bearing (12, 12n), comprising The provision of at least one location of reduced wall thickness (14), in particular a plurality of locations of reduced wall thickness (14, 14n), on the housing (2) and / or the at least one bearing shield (6, 20), in particular the provision of at least one cavity (22), in particular a plurality of cavities (22, 22n), and / or Attachment of at least one disc location of reduced wall thickness (30), in particular a plurality of disc locations of reduced wall thickness (30, 30n), to the radial bearing disc and / or axial bearing disc (28, 28'), in particular attachment of at least one disc cavity (32), in particular a plurality of disc cavities (32, 32n), in particular according to a method according to claim 8. [10] Use of the electric machine, in particular the air compressor (1), according to any one of claims 1 to 7 and / or the method according to claim 8 and / or the method according to claim 9 to increase the compliance of the electric machine, in particular the air compressor (1), and / or to compensate for manufacturing and / or assembly tolerances of the electric machine, in particular the air compressor (1).

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