DE102022121969A1 - Foil bearing, bearing arrangement and use of the foil bearing therein - Google Patents

Abstract

The invention relates to a foil bearing (1, 1') for supporting a rotating shaft (17), with a bearing bush (3) and one or more foils (5, 7, 31) arranged in the bearing bush (3), which are designed for this purpose , to extend circumferentially around the shaft (17) to be supported in such a way that when the shaft (17) rotates, an air cushion is built up which supports the shaft (17). It is proposed that the film bearing (1) has a number of air channels (15) for aerostatic support of the shaft (17), which extend continuously through the bearing bush (3) and the films (5, 7, 31).

Description

The present invention relates to a film bearing for supporting a rotating shaft, with a bearing bush and one or more films arranged in the bearing bush, which is or are designed to extend circumferentially around the shaft to be supported in such a way that when the shaft rotates an air cushion is built up that supports the wave.

Bearings of the type described above are well known. These bearings are generally used for the aerodynamic mounting of rapidly rotating shafts, for example in turbines or radial compressors, in order to be able to absorb radial forces with little friction and wear, even at several tens of thousands of revolutions per minute.

Aerodynamic bearings only work without wear when the rotating shaft has reached a predetermined speed, the so-called lift-off speed. Before this speed is reached, contact can occur between the shaft and the foils of the foil bearing, which leads to signs of wear over time. Therefore, conventional aerodynamic foil bearings are not well suited for applications in which frequent starting and stopping processes of the rotating shaft inevitably occur, because this significantly shortens the service life.

The invention was based on the object of improving a film bearing of the type described at the outset in such a way that the above disadvantages are mitigated as much as possible. In particular, the invention was based on the object of specifying a film bearing that can be operated with less wear without compromising the storage capacity at high speeds, and which at the same time can still be manufactured cost-effectively.

The invention solves the underlying problem with a film bearing according to claim 1. In particular, in a film bearing of the type described at the outset, the invention proposes that the film bearing has a number of air channels for aerostatic support of the shaft, which extend continuously through the bearing bushing and the Extend foils through.

The invention makes use of the knowledge that the air duct makes it possible to specifically blow in pressurized air through the bearing to the shaft and thereby support the shaft aerostatically when the bearing or the shaft mounted in the bearing has not yet reached the lifting speed has. The aerostatic support is only necessary until that event occurs. Once the lift-off speed is reached or exceeded, the film bearing according to the invention can then continue to be operated without aerostatic support thanks to the sufficiently strong air cushion. It was previously assumed that it would not be possible to combine aerostatic storage and aerodynamic storage in a single bearing because of the prejudice that introducing an air duct into the bearing would prevent the formation of the air cushion. However, it has turned out that this is not the case if it is possible to introduce the air in such a way that the effective surface is reached by the air. The effective surface is the surface of the rotating component, i.e. on the radial inside in the case of a radial bearing.

The fact that a continuous air duct runs through the bearing bush to the area where the shaft or the rotating component connected to the shaft and with which the bearing interacts is arranged in the assembled state, also ensures that The bearing air for aerostatic support arrives directly where it should go, namely into an annular gap in the interior of the bearing bush, which remains between the rotating component and the film or films.

The invention is advantageously further developed in that the bearing bush has a wall section which defines a bearing interior, the number of air channels each opening into the interior and, preferably in the area of the wall section as a radial through hole, are designed for blowing air into the bearing bush .

Preferably, the film bearing is a radial film bearing, and the number of air channels open into the interior in a radial direction. Alternatively, it is also possible to design the air channels as through passages, which are inserted into the bearing bush approximately in the axial direction, and are then deflected inside the bearing bush towards the interior of the bearing book, for example in the form of two blind holes opening into one another, which then form an angled one Form channel. However, the provision of a continuous radial channel in the form of a through hole has proven to be advantageous in terms of production technology.

The bearing bushing of the radial foil bearing consequently has a bushing wall delimited by an outer surface and an inner surface, which contains the wall section, and the through holes of the bearing bush extend from the outer surface to the inner surface through the bushing wall or the wall section into the interior of the bearing bush.

In a preferred embodiment, the films each have a number of through-holes, preferably radial ones, corresponding to the number of air channels, and the openings in the bearing bush and the through-holes are coaxially aligned with one another. This means that the number of continuous air channels from the bearing bush to the shaft is formed by a sequence of coaxial, adjacent passages. This also prevents the pressurized air conveyed through the air duct from pressing from the outside inwards against one or more foils in the interior of the bearing bush and pressing them against the shaft. The formation of the air cushion is promoted, and the films are kept away from the shaft or the corresponding rotating component that interacts with the bearing without wear, even in the operating mode of aerostatic support.

In a further preferred embodiment, the bearing bush and the immediately adjacent film or films lie against each other in the area of the mouths over the entire circumference of the through holes, preferably flat. This creates a gap-free seal between the film and the bearing bush on the one hand and between adjacent films on the other hand, which prevents or at least makes it more difficult for the blown-in pressurized air to escape to the side. This also promotes freedom from wear in the aerostatic operating mode as well as the formation of an air cushion for the aerodynamic operating mode.

In a further preferred embodiment, immediately adjacent films lie against each other in the area of the through-holes of the films over their entire circumference of the through-holes, preferably flat.

In a further preferred embodiment, a protuberance is formed around the through holes of the foils over their circumference, which extends to the adjacent mouth of the bearing bush, or through hole of an adjacent foil, preferably extends there, and particularly preferably over its entire circumference applied. This makes it even more difficult for air to escape from the sides. In the case of interlocking, the mechanical interlocking of the adjacent elements facilitates assembly and also promotes the coaxial alignment of the films relative to the mouth of the air duct.

In a further preferred embodiment, the bearing bushing and the immediately adjacent film or films adhere, and/or adjacent films adhere to one another in the area of the mouths or through holes, preferably by means of an adhesive.

In a further preferred embodiment, a sleeve element, preferably an elastically deformable sleeve element, extends from the mouth through the through holes in the films. The formation of an elastic sleeve element is advantageous because the films are pressed radially outwards during operation of the bearing due to the formation of the air cushion and are thereby pressed together in the radial direction. An elastic sleeve element can accommodate this movement and does not represent an obstruction to the air cushion during operation of the bearing.

In the foregoing, a number of such elements have been discussed abstractly with regard to the air ducts and through holes. A number is generally understood to mean a singular or a plural.

Particularly preferably, the film bearing has a plurality of air channels, particularly preferably three or more air channels, the air channels preferably being arranged evenly distributed over the circumference of the bearing bush. A uniform arrangement of the air channels over the circumference of the bearing bush ensures a uniform supply of pressurized air into the gap between the shaft and the foils, which promotes the supporting function.

In a further preferred embodiment, at least one innermost film extends over the entire circumference in the bearing bush. A cover film is preferably provided as the innermost film, and immediately adjacent thereto at least one spring film which extends over the entire circumference in the bearing bush, the spring film preferably being arranged adjacent to the inner surface of the bearing bush. One or more additional films can also be provided within the film structure.

The spring film is preferably designed as a wave or bump film, or as a cantilever film. The spring foil has the function of prestressing the foil structure in the radial direction against the shaft when the bearing is at a standstill, and of yielding in the radial direction as the speed of the shaft increases, so that a larger gap can form between the innermost foil and the shaft , in which the air cushion is created.

In a further preferred embodiment, the foils as foil segments of the foil bearing each extend over only part of the circumference in the bearing bush and overlap with each other nander such that the entire circumference of the bearing bush is lined with the foils, with the through holes of the foils each being arranged in the overlap area of adjacent foil segments.

This type of bearing is also known as leaf-type bearing. Arranging the through holes of the foils in the overlap area has the constructive advantage that the foils are already very close to one another due to their design principle, so that a smooth passage of the blown-in air radially inwards can be achieved without any special sealing measures.

In a further preferred embodiment of the film bearing, the films in the area of the through holes of the films or the mouth of the bearing bush are designed to rest against one another or to rest against the bearing bush in such a way that they are pressed against one another when pressurized air is applied to the number of air channels. This further restricts lateral escape of the injected bearing air, which further improves the efficiency of the support function in the aerostatic operating mode.

In a further preferred embodiment, the bearing bushing has a groove, preferably in an outer surface, which connects the air channels to one another in a fluid-conducting manner. This makes it possible to supply air to the bearing bush in a centralized manner via one or a small number of supply openings by not supplying the air channels directly, but instead supplying the groove with pressurized air, and then the pressurized air is distributed via the groove into the air channels.

The invention has been described above with reference to the foil bearing itself. In a further aspect, the invention also relates to a bearing arrangement for a compressor, in particular for a radial compressor of a fuel cell system of a commercial vehicle, with a bearing block, a film bearing with a bearing bush which is inserted into the bearing block, and a shaft mounted by means of the film bearing.

The invention solves the underlying problem in such a bearing arrangement in that the film bearing is designed according to one of the preferred embodiments described above, the film bearing preferably having a groove in the bearing bush, and the bearing block having one, preferably exactly one, air supply channel which is in the groove opens.

The air supply channel can also extend in the radial direction through the bearing block, but, like the air channel in the bearing bush, can also run in different directions. This also depends on the installation requirements of the bearing arrangement, for example in a compressor.

The bearing arrangement of the second aspect takes advantage of the same advantages as the foil bearing according to the first aspect. Preferred embodiments of the film bearing of the first aspect are at the same time preferred embodiments of the bearing arrangement and vice versa, which is why reference is made to the above statements to avoid repetition.

The invention also relates to the use of a film bearing, in particular according to one of the preferred embodiments described above, for supporting a shaft in a compressor, in particular in a bearing arrangement according to one of the embodiments described above, wherein the film bearing is optionally in a first, aerostatic, operating mode and /or is used in a second, aerodynamic, operating mode.

A particular advantage of the foil bearing according to the invention is evident in its use. One and the same foil bearing can be used for both aerostatic storage and aerodynamic storage. If both types of bearings are necessary or desired for supporting the shaft, it is not necessary to provide two different bearing arrangements, an aerostatic bearing arrangement and a separate aerodynamic bearing arrangement, but one and the same bearing can be used for both bearing tasks in different operating modes. This reduces the space required for storage, reduces the weight of the bearing arrangement and the compressor, and at the same time increases the service life of the foil bearing.

• 1 eine Querschnittsansicht durch ein Folienlager gemäß einem ersten Ausführungsbeispiel,
• 2 eine Detailansicht zu einem Folienlager gemäß 1,
• 3 eine Querschnittsansicht durch ein Folienlager gemäß einem zweiten Ausführungsbeispiel, und
• 4 eine Querschnittsansicht durch eine Lageranordnung gemäß einem bevorzugten Ausführungsbeispiel, geeignet zum Einsatz eines Lagers gemäß einer der 1 - 3.

The invention is described in more detail below with reference to the attached figures using preferred exemplary embodiments. Show here:

• 1 a cross-sectional view through a film bearing according to a first exemplary embodiment,
• 2 a detailed view of a foil warehouse according to 1 ,
• 3 a cross-sectional view through a film bearing according to a second exemplary embodiment, and
• 4 a cross-sectional view through a bearing arrangement according to a preferred Embodiment, suitable for using a bearing according to one of 1-3 .

The foil bearings shown in the figures and described below are each radial foil bearings. The invention also relates to axial foil bearings, in which the bearing air is not blown in in the radial direction, but in the axial direction, and supports the formation of the air gap between the running disk and the bearing foil(s). The principles described above in general and below in the specific figures can also be applied to those bearings according to the invention.

Having said that, it shows 1 a film bearing 1 designed as a radial film bearing, which has a bearing bush 3. Inside the bearing bush 3, a first film 5 is arranged as the innermost film and a second film 7 extending around it as a spring film is arranged. The two foils 5, 7 extend over the entire circumference inside the bearing bush 3. The bearing bush 3 has an outer surface 9, an inner surface 11 with an inner circumference 12, and a wall section 13 extending between the outer surface 9 and the inner surface 11 .

The film bearing 1 has a plurality of air channels 15 which extend continuously through the bearing bushing 3, the first film 5 and second film 7. Through the air channels 15, pressurized air L can be blown into an interior 18 inside the film bearing, past the films 5, 7 into an annular gap 19 between a shaft 17 to be stored and the cover film 5. The structure of the air channels 15 is in 2 shown in more detail.

2 the area of an opening 21 is shown for the bearing bush 3, which is as in 1 indicated, which can be the end of a through hole through the wall section 13. A through hole 23 of the second film 7 rests on the mouth 21 and is aligned coaxially with the mouth 21 in the direction of a radial axis R. The contact between the second film 7 and the mouth 21 preferably takes place between a protuberance 24 of the spring film 7 and an edge 25 of the mouth 21, over its entire circumference 22. As a result, incoming air L cannot flow unhindered laterally past the second film 7, but rather is at least largely conveyed through the second film 7. In the same way, the first film 5, designed as a cover film, lies closely against the second film 7 with a protuberance 26 of its through hole 27 coaxial to the radial axis R and also with its entire circumference 28. Incoming air L is thereby largely conveyed past the first film 5 into the inner annular gap 19.

Optionally, to further improve the flow guidance of the pressurized air L, a sleeve element 29 is arranged in the air duct 15, which extends from the area of the mouth 21 into the inner annular gap 19 and also passes through the through holes 23, 27 of the first and second foil 5,7 in order to make it even more difficult for the pressurized air L to flow out laterally. The sleeve element 29 is preferably made of an elastic material in order to be able to accommodate any compression movements of the foils, in particular the spring foil 7, during operation.

If the films are sufficiently deformable, the through holes can be arranged together by means of their protuberances, which can be produced, for example, by punching, and/or by means of an adhesive, but also without a sleeve element. A hermetic seal at the through-holes is not necessary; it has been found that it is sufficient if a majority of the blown-in air flows through the through-holes.

In 3 A foil bearing 1′ designed as a radial foil bearing is shown according to a second preferred exemplary embodiment. While the foil bearing 1 of the 1 and 2 was designed as a bump-type foil bearing, the foil bearing 1 'according to 3 designed as a leaf-type foil bearing. The foil bearing 1', like the foil bearing 1, has a bearing bushing 3 in which a shaft 17 is to be rotatably mounted. From the inner surface 11 of the bearing 1 'several films 31 extend as film segments, each of which only runs around a part of the circumference of the bearing bush 3, but each overlaps one another in an overlap area 33, so that in total the entire inner circumference of the bearing bush 3 is covered with films 31 is lined.

Also the foil bearing 1 'according to 3 has a plurality of air channels 15, which are distributed evenly over the inner circumference 12 of the bearing bush 3 and which run continuously from the outer surface 9 of the bearing bush 3 into an inner annular gap 19 between the shaft 17 and the bearing bush 3 or the foils 31 to be able to transport pressurized air past the foils 31 to the shaft 17, and to be able to aerostatically support the shaft 17 before it reaches its take-off speed.

The fact that the air channels 15 are arranged in the overlap area 33 between adjacent foils 31 ensures that they are elastically prestressed against the shaft 17 in the resting state Foils 31 lie close to one another, and the air L blown into the air duct 15 does not escape to the side, but can pass directly into the annular gap 19 between the shaft 17 and the foils 31. Depending on the length of the foils 31, it can be as in the exemplary embodiment shown 3 In addition, each film 31 has more than one through hole 35. The through hole 35 of the foils 31 are also aligned coaxially with the respective mouths 21 in the bearing bush 3.

4 shows an example of a bearing arrangement 100 for a compressor, in particular a radial compressor of a fuel cell system. The bearing arrangement 100 has a bearing block 39 which has one, preferably exactly one, air supply channel 41 for supplying pressurized air L. A bearing bush 3 is inserted into the bearing block 39 and is set up to receive one of the film bearings 1, 1 '. The bearing bushing 3 has a number of air channels 15, each of which has an opening 21 on the inner surface 11 of the bearing bushing 3 and which are designed to interact with corresponding air channels 15 of the film bearings 1, 1 'to bring pressurized air L into the interior of the film bearing 1, 1 'to initiate aerostatic support in a first operating mode intended for this purpose.

To distribute the pressurized air L, the bearing bushing 3 preferably has a groove 37 which extends circumferentially on the outer surface 9 of the bearing bushing 3 and connects the air channels 15 to one another in a fluid-conducting manner. In this way, it can be structurally easily ensured that the pressurized air L introduced into the air supply channel 41 is distributed circumferentially and can enter the air channels 15. In this way, when starting the rotational movement of the shaft 17 in a first operating mode, aerostatic support of the bearing can be carried out by supplying air, so that wear on the sensitive foils 5, 7, 31 is minimized. When the lift-off speed is reached, or when other operating criteria occur, the aerostatic support can be ended in a second operating mode because from that point on an air cushion forms between the shaft and the foils 5, 31, which carries the shaft 17.

As can be seen from the above explanations, the invention proposes a film bearing which is suitable for hybrid use in aerostatic and aerodynamic operation, and which is particularly suitable for minimizing wear in the start-up and run-down process compared to classic aerodynamic bearings.

Reference symbols (part of the description):

1, 1'

Foil bearing

3

Bearing bushing

5

Film: cover film

7

Foil: spring foil

9

Outer surface, bearing bush

11

Inner surface, bearing bush

12

inner circumference, bearing bush,

13

Wall section, bearing bush

15

Air duct

17

Wave

18

Warehouse interior

19

Annular gap

21

mouth

22

Circumference, mouth/through hole (spring foil)

23

Through hole, spring foil

24

Protuberance, spring foil

25

Edge

26

Protuberance, cover film

27

Through hole, cover film

28

Circumference, through hole (cover film)

29

sleeve element

31

Foil segment

33

Overlap area, segment foils

35

Through hole, segment film

37

Nut

39

bearing block

41

Air supply duct

100

Storage arrangement

L

pressurized air

R

Radial axis

Claims (16)

Foil bearing (1, 1') for supporting a rotating shaft (17), with a bearing bush (3) and at least one, preferably several foils (5,7,31) arranged in the bearing bush (3), which are designed for this purpose to extend circumferentially around the shaft (17) to be supported in such a way that when the shaft (17) rotates, an air cushion is built up which supports the shaft (17), characterized in that the film bearing (1) has a number of Air channels (15) for aerostatic support of the shaft (17), which extend continuously through the bearing bush (3) and the films (5, 7, 31). Foil bearing (1, 1') after Claim 1 , characterized in that the bearing bush (3) has a wall section (13) which defines a bearing interior (18), the number of air channels (15) each opening into the bearing interior (18), and for blowing in pressurized Air (L) is formed into the bearing bushing (3). Foil bearing after Claim 1 or 2 , wherein the film bearing is designed as a radial film bearing and the number of air channels (15) each open into the bearing interior (18) in the radial direction. Foil bearing (1, 1') according to one of the preceding claims, characterized in that the foils (5, 7, 31) each have a number of, preferably radial, through holes (23, 27, 35) corresponding to the number of air channels (15). , and that the mouths (21) in the bearing bush (3) and the through holes (23, 27, 35) of the foils (5, 7, 31) are coaxially aligned with one another. Foil bearing (1, 1') according to one of the preceding claims, characterized in that the bearing bush (3) and the immediately adjacent foil (7) or foils (31) in the area of the mouths (21) over the entire circumference (22) of their Through holes (23, 35) rest against each other, preferably flat. Foil bearing (1) according to one of the preceding claims, characterized in that immediately adjacent foils (5, 7, 31) in the area of the through holes (27, 35) of the foils (5, 31) over the entire circumference (28) of the through holes (27, 35) rest against each other, preferably flat. Film bearing (1) according to one of the preceding claims, characterized in that a protuberance (24, 26) is formed around the through holes (23, 27) of the films (7), which extends towards the adjacent mouth (21) of the bearing bush ( 3), or the through hole (27) of an adjacent film (5), extends towards, preferably extends into there, and more preferably rests there over the entire circumference (22, 28). Foil bearing (1) according to one of the preceding claims, characterized in that the bearing bush (3) and the immediately adjacent foil (7, 31) in the area of the mouths, and / or each adjacent foil (5, 7, 31), in the area the through holes (23, 27, 35) adhere to one another, preferably by means of an adhesive. Film bearing (1) according to one of the preceding claims, characterized in that the film bearing (1) has several, preferably 3 or more, air channels (15), the air channels (15) preferably being uniform over the inner circumference (12) of the bearing bush ( 3) are arranged distributed. Foil bearing (1) according to one of the preceding claims, characterized in that at least one innermost foil (5) extends over an entire inner circumference (12) of the bearing bush (3). Foil bearing (1). Claim 10 , characterized in that a cover film is provided as the innermost film (5), and immediately adjacent to it is a spring film (7), which extends over the entire inner circumference (12) of the bearing bush (3), the spring film (7) preferably being adjacent to the bearing bush (3) is arranged. Foil bearing (1') according to one of the Claims 1 until 10 , characterized in that the films (31) each extend over a part of the inner circumference (12) in the bearing bush (3) and overlap with one another in such a way that the entire inner circumference (12) of the bearing bush (3) is lined, whereby the through holes (35) of the films (31) are each arranged in an overlap area (33) of adjacent films (31). Foil bearing (1) according to one of the preceding claims, characterized in that the foils (5, 7, 31) are attached to one another in the area of the through holes (23, 27, 35) or in the area of the mouths (21) to the bearing bush ( 3) ensure that they are pressed against each other when pressurized air (L) is applied. Foil bearing (1, 1') according to one of the preceding claims, characterized in that the bearing bush (3) has a groove (37), preferably in an outer surface (9), which connects the air channels (15) to one another in a fluid-conducting manner. Bearing arrangement (100) for a compressor, in particular for a radial compressor of a fuel cell system of a commercial vehicle, with a bearing block (39), a film bearing (1, 1 ') with a bearing bush (3), which is inserted into the bearing block (39), and a shaft (17) mounted by means of the film bearing (1), characterized in that the film bearing (1) is designed according to one of the preceding claims, wherein before preferably the foil bearing (1). Claim 14 is formed, and the bearing block (39) has one, preferably exactly one, preferably radial, air supply channel (41) which opens into the groove (37). Use of a foil bearing (1) according to one of the Claims 1 until 14 in a bearing arrangement (100). Claim 15 , either in a first, aerostatic operating mode and / or in a second, aerodynamic operating mode.

Images