Foil bearing

Abstract

Bearing (1) comprising a rotor (3) and a bearing means (11), wherein the rotor (3) is rotatably mounted by means of the bearing means (11), characterized in that the rotor (3) and / or the bearing means (11) is provided with an anti-abrasive coating (13).

Description

[0001] R.416187

[0002] - 1 -

[0003] Description

[0004] title

[0005] Storage

[0006] The invention relates to a bearing with a rotor which is rotatably mounted.

[0007] State of the art

[0008] Plain and rolling bearings are often lubricated with oils or greases to reduce friction and wear. However, in some applications, this type of lubrication is undesirable to avoid contamination, unpleasant odors, or health hazards, for example, in semiconductor manufacturing, HVAC systems, or food processing. Air and hydrogen compressors in fuel cells also have stringent cleanliness requirements. Oil mist from lubricants would be carried by the gas flow into the fuel cell stack and damage it. Therefore, aerodynamic foil bearings, also known as gas or air bearings, are used. At high speeds, these bearings generate an aerodynamically load-bearing gas film between a rotating shaft and the bearing element. Lubrication to reduce friction is not required in this case.At low speeds, however, the shaft is in direct frictional contact with the bearing, and both parts can wear. This can be reduced by a coating. Polytetrafluoroethylene (PTFE) is frequently used as a coating material, specifically R.416187.

[0009] - 2 -

[0010] Solid lubricant is used. Due to an upcoming international regulation, a so-called "PFAS" ban, the use of PTFE may be prohibited or severely restricted in the future.

[0011] Foil bearings, in particular radial foil bearings, are known, for example, from German patent applications DE 10 2018 222 572 A1 and DE 10 2018 222 603 A1. Such foil bearings are used, for example, in an air compressor of a fuel cell system for the radial support of a rotor shaft of an electric motor drive of the air compressor.

[0012] Spring foils of such radial foil bearings are known, for example, from the subsequently published German application with the file number 102023206260.7.

[0013] Disclosure of the invention

[0014] The object of the invention is to improve a bearing according to the preamble of claim 1 with regard to its function, for example, in operation in a gas conveying device, particularly in an air compressor, where very high rotational speeds of, for example, one hundred thousand revolutions per minute can occur. A wear-resistant coating advantageously serves to protect against wear, in the case of a gas or air bearing, particularly at low rotational speeds, i.e., when the rotational speed is still too low for the formation of a load-bearing gas film and a metallic shaft or rotor can thus come into direct frictional contact with a metallic bearing element. Such contact would lead to severe wear and even to the spontaneous destruction of the bearing.

[0015] The measures listed in the dependent claims enable advantageous further developments and improvements of the bearing specified in the independent claim. R.416187

[0016] - 3 -

[0017] It is particularly advantageous to form a wear-resistant coating that is a polymer coating and contains a substance from the polyetherketone group.

[0018] With regard to temperature resistance, polyetherketones advantageously allow higher operating temperatures than, for example, PTFE, which means that previous limitations in the operating range, for example in electric air compressors for fuel cells, are less or no longer relevant.

[0019] This also makes it possible to do without the material PTFE, while maintaining essential required properties such as the flexibility of the film in film storage, chemical and thermal resistance, the possibility of initial smoothing of the surface in frictional contact, and the reduction of static friction when stationary.

[0020] Furthermore, many bearing dimensions can be retained when switching from PTFE to polyetherketones, as the coatings are externally similar. This simplifies the replacement of PTFE.

[0021] Further advantages, features and details of the invention will become apparent from the following description, in which various embodiments are described in detail with reference to the drawing.

[0022] Brief description of the drawing

[0023] It shows

[0024] Figure 1 shows a camp. R.416187

[0025] - 4 -

[0026] Description of the exemplary implementations

[0027] Figure 1 shows an exploded view of a bearing 1. The bearing comprises a bearing element 11, which supports a rotor, symbolically represented by the rotor axis or axis of rotation 3. The bearing element includes a foil or cover foil 5, which can alternatively be made up of multiple parts, a bearing bushing 7, and a spring foil 9. In the intended operation of the bearing 1, the foil 5 and the spring foil 9 are located within the bearing bushing 7, with the spring foil 9 positioned between the cover foil 5 and the bearing bushing 7. The cover foil 5 directly surrounds the rotor 3. At least on its side facing the rotor, the cover foil 5 has a wear-resistant coating 13. Alternatively or additionally to such a coating on the cover foil, the surface of the rotor, at least in the area of ​​the bearing, can also have a corresponding wear-resistant coating, not shown in detail.

[0028] The bearing shown in Figure 1 is designed as a foil bearing, specifically as a radial foil bearing. Here, the rotor is encased by one or more foil pieces forming the cover foil 5, which rest on a flexible corrugated or spring foil 9, which in turn is supported in the bearing bushing 7. The cover foil is coated at least on the contact surface with the shaft or rotor.

[0029] This wear-resistant coating 13 contains a plastic or polymer, preferably polyetherketone (PEK), and has a layer thickness of approximately 20 to 40 micrometers, preferably approximately 25 to 35 micrometers, and most preferably approximately 30 micrometers.

[0030] The polyetherketone can be used directly in this form as a material, or in modified form as polyetheretherketone (“PEEK”), as polyetherketoneketone C.PEKK”), as polyetheretheretherketone C.PEEEK”), as polyetheretherketoneketone C.PEEKK”), as polyetherketoneetherketoneketone C.PEKEKK”), or in other modifications belonging to the polyetherketone family of substances. R.416187

[0031] - 5 -

[0032] Optionally, substances that modify friction and / or wear can be added to the layer.

[0033] Other bearings, such as axial bearings, can also be equipped with such a wear protection coating 13.

[0034] The bearing according to the invention can be used in particular for gas compressors for fuel cells, for example in an electrically driven air compressor. Furthermore, the bearing can also be used in other air-bearing designs for rotating technical elements, including designs in which rotating technical elements are intermittently or continuously in frictional contact with the bearing element during intended continuous operation, but where no liquid or grease lubrication is provided.

Claims

R.416187 - 6 - Claims 1. Bearing (1) with a rotor (3) and a bearing means (11), wherein the rotor (3) is rotatably mounted by means of the bearing means (11), characterized in that the rotor (3) and / or the bearing means (11) is provided with a wear-resistant coating (13).

2. Bearing (1) according to claim 1 , characterized in that the wear protection coating (13) is a polymer coating.

3. Bearing (1) according to claim 2, characterized in that the polymer coating contains or consists of a polyetherketone.

4. Bearing (1) according to claim 3, characterized in that the polyetherketone is a polyetheretherketone, a polyetherketoneketone, a polyetheretheretherketoneketone, a polyetheretherketoneketone or a polyetherketoneetherketoneketone.

5. Bearing (1) according to one of the preceding claims, wherein the wear protection coating (13) has a layer thickness of approximately 20 to 40 micrometers, preferably of approximately 25 to 35 micrometers and most preferably of approximately 30 micrometers.

6. Bearing (1) according to one of the preceding claims, characterized in that it is designed as a radial bearing.

7. Bearing (1) according to one of the preceding claims, characterized in that the bearing means (11) has at least one foil (5, 9) for forming an air bearing of the rotor.

8. Bearing (1) according to claims 6 and 7, characterized in that the foil (5) is arranged within a bearing bushing (7) of the bearing means (11).

9. Bearing (1) according to claim 8, characterized in that a spring foil (9) of the bearing means (11) is clamped between the foil (5) and the bearing bushing (7).

10. Bearing (1) according to claim 7, 8 or 9, characterized in that the at least one foil (5) surrounds the rotor.

11. Bearing (1) according to one of claims 7 to 10, characterized in that the film (5) has the wear protection coating (13) at least on one side, in particular on a side facing the rotor. R.416187 - 7 - 12. Foil (5) of a bearing according to one of claims 7 to 11 for the rotatable mounting of a rotor (3), characterized in that it has the wear-resistant coating (13) at least on one side, in particular on a side facing the rotor.

13. Rotor (3) for a bearing (1) according to one of claims 1 to 11, characterized in that it is provided with a wear-resistant coating (13).

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