Radial foil bearing having carrier foil-fastening of carrier foil in outer ring by means of curved hooks

Abstract

The invention relates to a radial foil bearing (1) comprising at least one top foil (2) and at least one bump foil (3), the top foil (2) and the bump foil (3) being formed one above the other in the radial direction (9) and the foils (2, 3) forming at least one arc-shaped section (6) of the radial foil bearing (1) in the circumferential direction (10), wherein there is a first arc-shaped section (6a) consisting of a first top foil (2a) and a first bump foil (3a) which are firmly connected to one another at a common end, the first arc-shaped section (a) being firmly arranged on the carrier foil (4), a second arc-shaped section (6b) consisting of a second top foil (2b) and a second bump foil (3b) which are firmly connected to one another at a common end is arranged on the carrier foil (4), and the two arc-shaped sections (6a, 6b) are arranged one behind the other on the carrier foil (4) such that, when the carrier foil (4) is rolled up, a first arc-shaped section (6a, 6b) having the two arc-shaped sections (6a, 6b) is produced. The invention relates to a radial foil bearing (1), comprising a tubular carrier (7) comprising at least one carrier foil (4) (6a, 6b) and forming a radial foil bearing (1), the carrier foil (4) having, in the unrolled state, at a delimiting surface (19) thereof extending in the longitudinal direction of the carrier foil (4), at least one web (11) projecting from the delimiting surface (19), after the carrier foil (4) has been rolled into the tubular carrier (7), the at least one web is used as an orientation means for angularly inserting the tubular carrier (7).

Description

Technical Field

[0001] Radial foil bearings are designed for aerodynamically supporting shafts, wherein a load-bearing gas / air cushion is formed between the shaft and the radial foil bearing. The operating principle is similar to that of a hydrodynamic plain bearing, but with the following difference: the shaft is supported by the radial foil bearing via the air cushion and not by the liquid cushion of a hydrodynamic plain bearing. Both operating principles have the following in common: a first rotational direction of the shaft causes the formation of a load-bearing cushion.

[0002] Foil bearings differ from conventional aerodynamic bearings in the flexible, elastic arrangement between the rotating shaft and the stationary housing component. This feature allows the bearing to be less rigid than conventional air bearings, but to adapt to geometric air gap changes due to, for example, misalignment of the bearing seat or different thermal expansions of the shaft and housing, thereby achieving higher operational reliability in many applications.

[0003] In order to form a load-bearing air cushion, a radial foil bearing usually has a top foil in contact with the stationary shaft and a bump foil arranged radially between the top foil and the outer ring of the bearing, which is elastically compressible in the radial direction. In principle, a radial foil bearing therefore has two foils in contact with each other and an outer ring that carries the foil so that the radial foil bearing can be accommodated in a housing. The outer ring can also be formed in one piece by a housing, into which the foil of the radial foil bearing is inserted.

[0004] If the shaft is set into rotational motion relative to the radial foil bearing, the gap present in the air gap defined by the idle state is compressed. From a certain rotational speed of the shaft, an air cushion is formed between the top foil and the shaft, on which the shaft can slide. The foil pack with its bump foils and its radial spring action ensures that vibrations of the shaft or fluctuations in the air pressure in the radial direction of the bearing are not affected, so that the air cushion remains load-bearing. Background Art

[0005] A variety of foil bearing designs are known in the prior art. In addition to radial foil bearings, there are also axial foil bearings that can provide axial load-bearing capacity. The arrangement of the foils of the bearing and their geometrical design are diverse and can be adapted to any application.

[0006] US2015 / 292552A and US2011 / 052110A respectively show the construction of radial foil bearings. Summary of the invention

[0007] The object of the present invention is to provide an improved radial foil bearing.

[0008] The radial foil bearing according to the present invention has multiple, preferably three, arcuate segments, wherein there is a first arcuate segment consisting of a first top foil and a first wave foil firmly connected to each other at a common end, wherein the first arcuate segment is firmly arranged on a carrier foil, wherein a second arcuate segment consisting of a second top foil and a second wave foil firmly connected to each other at a common end is arranged on the carrier foil, wherein the two arcuate segments are successively placed on the flat carrier foil, so that when the carrier foil is rolled up, a tubular carrier having two arcuate segments is produced and forms a radial foil bearing.

[0009] The carrier foil is preferably formed from a thin (<0.5 mm) steel strip of stainless spring steel sheet, which can be bent into a circular shape by hand or with the aid of auxiliary equipment.

[0010] The arc segments are formed by a top foil and a bump foil which are firmly connected to each other at the ends. Subsequently, the arc segments are placed successively on the carrier foil, wherein two consecutive arc segments are spaced apart from each other, so that when the carrier foil which has been flatly unrolled so far is rolled up to form a tubular carrier, the end of one arc segment overlaps the subsequent end of the subsequent arc segment to a small extent, abuts against each other or is slightly spaced apart from each other. Thus, at least two arc segments are provided in order to characterize their successive arrangement on the carrier foil, wherein three consecutive arc segments can advantageously be provided for the function of the bearing.

[0011] Here, the previously flat carrier foil is wound around the arc segment so that the carrier foil has wrapped around and surrounds the arc segment. Thus, after forming the tubular carrier, the carrier foil follows the foils formed by the top foil and the corrugated foil in the radial direction.

[0012] The arc-shaped section is connected firmly to the carrier foil indirectly and / or directly at the end.

[0013] In order to place the arc segment securely on the carrier foil with the ends at which the two foils are connected to each other and to fasten them, the carrier foil has a positioning means, for example in the form of a recess, which can be placed against or aligned with the ends of the arc segment. Advantageously, the positioning means are designed as holes in the strip-shaped carrier foil so that they are easily accessible for tools to align the arc segment with the positioning means.

[0014] This has the advantage according to the invention that the radial foil bearing can be inserted directly into a bearing receiving hole, for example, of a compressor housing as a component consisting of an arc segment and a supporting foil, or can be connected to a bearing outer ring sleeve as a self-supporting unit consisting of an arc segment and a supporting foil, which can then be installed in the unit.

[0015] The radial foil bearing according to the invention can therefore preferably be used for oil-free and rapidly rotating rotor supports, for example in fuel cell compressors, electric superchargers or turbochargers, wherein the design of the radial foil bearing according to the invention enables mass production that is as cost-effective as possible and furthermore provides the possibility of a modular construction that covers different requirements for the implementation of the radial foil bearing in a unit assembly.

[0016] Within the scope of the present invention, the carrier foil in the unrolled state has at least one web protruding from the boundary surface at its boundary surface extending in the longitudinal direction of the carrier foil, which web serves as an orientation means for angularly correct insertion of the tubular carrier after the carrier foil has been rolled into a tubular carrier.

[0017] Here, the boundary surface is not that face of the carrier foil on which the arcuate segments are fastened or placed. Instead, the boundary surface is that face of the flat, unfolded carrier foil which, after the carrier foil is rolled up, forms a quasi-circular end face of the tubular carrier. Thus, in the flat, unfolded state of the carrier foil, the boundary surface is directional for the maximum length of the foil. Thus, successive arcuate segments can be seen along the extension of the boundary surface.

[0018] Advantageously, a plurality of tabs are formed by the carrier foil. A single tab according to the invention of the carrier foil is already the minimum requirement. After the tubular carrier and the outer ring have been mounted, at least one tab engages in a receptacle of the outer ring that is matched to each tab, whereby the tubular carrier is angularly correctly oriented and held within the outer ring. Particularly preferably, a coupling pair consisting of a tab and a receptacle is present on each end face of the outer ring, with each pair of tabs and receptacles ensuring angularly correct orientation. This not only ensures anti-twist resistance between the tubular carrier and the outer ring, but also prevents the tubular carrier from axially moving away from the outer ring during operation of the radial foil bearing.

[0019] In an advantageous embodiment of the invention, at least one web protrudes in the axial direction beyond the axial extent of the arc-shaped section.

[0020] Furthermore, the invention proposes that the tubular carrier is inserted into the outer ring. The outer ring is also formed in one piece by the housing, rather than being present as a separate component. Clearly, the configuration of the outer ring as a separate component or as a component inherent in the housing has the features according to the invention.

[0021] The tubular carrier is bent out / rolled / curved from the flat carrier foil. This is done with the aid of an additional tool, which brings the flat carrier foil into the shape of the tubular carrier. The shape of the tubular carrier can be kept in place with the aid of an additional tool until the tubular carrier is pushed into the outer ring or without additional tools, wherein a material is selected for the carrier foil that allows the plastic state to be assumed.

[0022] Here, in another design, at least one web is configured to protrude in the axial direction beyond the axial dimension of the outer ring limited by its end face. At least one web of the tubular support installed in the outer ring is therefore accessible from the outside to be bent into the receiving portion of the outer ring.

[0023] Alternatively, before the tubular support is installed in the outer ring, at least one tab can be bent in a hooked manner. In this case, the hooked tab is locked in the receiving portion provided for this purpose after successful installation and the tubular support is fixed in the outer ring.

[0024] In a particularly advantageous embodiment, at least one tab is engaged in a radial direction into a corresponding receptacle of the outer ring designed for at least one tab. At least one tab is bent radially outwards after the tubular support has been successfully assembled into the outer ring so that it can be engaged in the receptacle. At least one tab is preferably bent into a hook at an angle of approximately 90° so that the circumferential edge of the bent tab together with the circumferential boundary of the receptacle can achieve anti-twist and the inner surface of the tab can achieve axial fixation in two directions. At least one tab can be bent out on an already flat support foil, which is then bent into a tubular support. Subsequently, a tubular support with the bent tab is already present.

[0025] If a plurality of webs and associated receptacles are provided on the end face of the outer ring, the functions of axial fixing of the tubular carrier in the outer ring and anti-twist protection of the tubular carrier relative to the outer ring can be associated separately from one another with the joint pairs formed by the webs / recesses. Thus, at least one joint pair for axial fixing has more play in the circumferential direction than the joint pair for anti-twist protection.

[0026] Advantageously, the functional distribution described can compensate for possible shape inaccuracies of the tubular carrier, for example due to non-full-surface contact between the tubular carrier and the inner side of the outer ring. The introduction of the shaft compensates for such shape errors, wherein the shaft presses the carrier foil outwardly onto the inner side of the outer ring via the top foil and the bump foil.

[0027] This can be achieved by means of a joint pair with increasing clearance in the circumferential direction, since there is no circumferential contact - the fixing of the circumferential degree of freedom is preferably undertaken by a single joint pair per end face of the outer ring. As a result, the installation forces for the split shaft are reduced, the bearing play is optimized, and the preload of the bump foil is not unreasonably overused. In addition, the friction torque and the acceleration speed are also reduced when the shaft is started. This in turn has a positive impact on the service life of the top foil and thus also the radial foil bearing.

[0028] Advantageously, the receptacle is recessed into the material at the end face of the outer ring. This saves axial installation space and protects the webs of the carrier foil from damage during handling and assembly.

[0029] In another embodiment of the invention, the receptacle is not only recessed at the end face but also recessed into the material at the outer side of the outer ring. Advantageously, the bent tab engages in the axially and radially recessed receptacle and fixes the tubular support in the axial direction. In addition, the tubular support is now better placed on the inner circumferential surface of the outer ring, so that the less dimensionally stable tubular support has the precise shape accuracy of the more dimensionally stable outer ring. As a result, the wedge-shaped gap geometry required for the function between the top foil and the shaft is ensured despite the shape tolerances caused by the manufacture of the support. In addition, the minimum inscribed circle diameter is not exceeded, thereby ensuring or simplifying the splicing of the shaft.

[0030] The bent web is joined to the radially set back receptacle or the receptacle widening in such a way that no part of the web penetrates into the envelope describing the outer side and does not hinder the installation of the outer ring into the receptacle opening of the housing. The web in the receptacle is therefore bent inwards not only towards the outer side but also towards the end face without protrusions.

[0031] The embodiment according to the invention is particularly preferred in which one of the at least one web engages in a radial direction in a corresponding receptacle of the outer ring provided for the at least one web and orients the tubular carrier in an angularly correct manner within the outer ring. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The advantageous embodiments of the present invention are described in detail in the following drawings. The drawings show:

[0033] Figure 1 A first view showing a flatly unfolded carrier foil having a plurality of arc-shaped segments mounted thereon,

[0034] Figure 2 Show Figure 1 A second view of the flatly unfolded carrier foil in FIG.

[0035] Figure 3The carrier foil and the outer ring of the carrier rolled into a tube before being joined together are shown,

[0036] Figure 4 Shows the carrier piece that is spliced ​​into the outer ring to form a radial foil bearing,

[0037] Figure 5 Show according to Figure 4 A radial foil bearing having a web engaging in a receptacle of an outer ring,

[0038] Figure 6 Show according to Figure 5 A top view of the end face of a radial foil bearing, and

[0039] Figure 7 Show Figure 5 A variation of the receiving portion of the outer ring in. DETAILED DESCRIPTION

[0040] Figure 1 The first view of the flatly unfolded carrier foil 4 is shown, which specifically has a plurality of arc sections 6 mounted thereon. The carrier foil 4 has a main extension direction transverse to the subsequent axial direction 8 after the carrier foil 4 is rolled into a tubular carrier 7. The arc sections 6 are triple 6a, 6b and 6c and are successively fastened to the carrier foil 4. The arc sections already have a pre-bent profile consistent with the subsequent circumferential direction 10 after the carrier foil 4 is rolled into a tubular carrier 7. Each arc section 6a, 6b or 6c has a top foil 2a, 2b or 2c respectively and has a wave foil 3a, 3b or 3c respectively. The splice 11 according to the present invention is composed of a single material of the carrier foil 4 and extends flatly from the limit surface 19 that limits the carrier foil 4 just as the carrier foil 4 is flatly unfolded. The limit surface 19 extends along the above-mentioned main extension direction and limits the carrier foil 4 on both sides. No arc-shaped section 6 is arranged on the boundary surfaces 19 which form the webs 11 and project from the extent of the respective boundary surface 19 .

[0041] Figure 2 Show Figure 1 A second view of the flatly unfolded carrier foil in FIG. Figure 1 In addition to the description, the bump foils 3a, 3b and 3c can be observed. From it, it can be seen that each bump foil 3a, 3b, 3c has a middle slit, which however does not divide the bump foil itself into two independent parts.

[0042] Figure 3The carrier foil 4 and the outer ring 5 are shown rolled up into a tubular carrier 7 before being joined together. By rolling up the carrier foil 4, the arc segments 6 are arranged successively in the circumferential direction 10 and form the functionally important part of the radial foil bearing 1. The tubular carrier 7 itself maintains its tubular shape or is maintained in the tubular shape by a tool not shown here. The outer ring 5 should accommodate the tubular carrier 7 and resist damage when the radial foil bearing 1 is inserted into the receiving hole of the housing. First, the tubular carrier 7 and the outer ring 5 are coaxially aligned with respect to the center axis 15, but have an axial spacing from each other. It can be clearly seen that the boundary surface 19 now forms a circular shape in its extension, and the web 11 extends from the circular shape in the axial direction 8.

[0043] The outer ring 5 has a receiving bore adapted to the tubular carrier 7 and is designed as a sleeve or ring without a base by means of an outer side 18 concentric therewith. A plurality of receptacles 12 are arranged on its end faces 16, 17 axially delimiting the outer side 18, which are each recessed in the axial direction into the material of the outer ring 5 and form a type of "pocket" for the webs 11. Each end face 16 and 17 has three receptacles 12, even though the third receptacle 12 remains covered by the outer ring 5 itself on the rear side of the outer ring in this view. The number of receptacles 12 thus corresponds to the number of webs 11.

[0044] Figure 4 The tubular carrier 7 is shown, which is inserted into the outer ring 5, in order to form the radial foil bearing 1. The radial foil bearing 1 is now present in the form of a matching tubular carrier 7 which is inserted into the outer ring 5. The webs 11 are oriented at an angle relative to the corresponding receptacles 12, so that the subsequently bent webs 11 can engage in their matching and associated receptacles 12. The tubular carrier 7 is now rotated relative to the outer ring 5 in the circumferential direction 10 in order to calibrate the angularly correct orientation relative to one another.

[0045] Figure 5 Show according to Figure 4 A radial foil bearing 1 is shown, which has a web 11 that engages in a receptacle 12 of an outer ring 5. A tool (not shown here) bends the web 11 away from its initial position relative to the axial direction 8 at an angle, so that the web 11 engages in the receptacle 12 as a hook in the radial direction relative to the center axis 15 - each web 11 engages in its receptacle 12 provided for this purpose. The depth of each receptacle 12 in the axial direction 8 is dimensioned so that the bent web 11 is completely immersed in its receptacle 12, without a part of the web 11 protruding from the end face 16 or 17 or the outer side 18.

[0046] Figure 6 Show according to Figure 5The top view of the end face of the radial foil bearing 1 is shown in FIG. The top view is shown along the circumferential direction 10 relative to the previous Figure 5 The view is rotated so that the special tab 11 with its special receiving portion 12 returns to the 8 o'clock position - at Figure 5 , the special engagement pair is located at the 11 o'clock position. The special web 11 and its special receptacle 12 have a small gap, so that the engagement pair can be referred to as an oriented engagement pair consisting of an orientation web 13 and its orientation receptacle 14. The oriented engagement pair determines the angular position between the outer ring 5 and the tubular support 7, while the remaining engagement pair consisting of web 11 and receptacle 12 at the end face 16 and the engagement pair on the opposite end face 16 or 17 assume the axial determination of the tubular support 7 in the outer ring 5. The two other engagement pairs on the visible end face 16 or 17 have a circumferential spacing between the web 11 and its receptacle 12 that is larger than the circumferential spacing of the oriented engagement pairs.

[0047] Figure 7 Show Figure 5 . The pocket-shaped receptacle 12 of the previous figures is widened by the region on the outer side 18 that is recessed into the material of the outer ring 5 so that the bent-over web 11 can surround the outer ring 5. In addition to the axial fixation along the axial direction 8 and the center axis 15, radial fixation of the tubular support 7 is also assumed in the described manner, so that the tubular support 7 remains centered in the receiving opening of the outer ring 5. During operation of the radial foil bearing 1, the bent-over web 11 is also advantageous in order to support the support foil 4 more securely on the outer ring 5 and thus to almost minimize any radial play between the tubular support 7 and the outer ring 5.

[0048] Description of Reference Numerals

[0049] 1Radial foil bearing

[0050] 2 top foils

[0051] 2a First top foil

[0052] 2b Second top foil

[0053] 2c Third top foil

[0054] 3 wave foil

[0055] 3a First wave foil

[0056] 3b Second wave foil

[0057] 3c Third Wave Foil

[0058] 4 Carrier foil

[0059] 5 Outer Ring

[0060] 6 arc segments

[0061] 6a The first arc segment

[0062] 6b Second arc segment

[0063] 6c The third arc segment

[0064] 7 Tubular support

[0065] 8 Axial direction

[0066] 9 Radial direction

[0067] 10 Circumferential direction

[0068] 11 splice

[0069] 12 Accommodation

[0070] 13 Directional splices

[0071] 14 directional accommodation portion

[0072] 15 Central Axis

[0073] 16 End face

[0074] 17 End face

[0075] 18 Outer side

[0076] 19 limit interface

Claims

1. A radial foil bearing (1), comprising at least one top foil (2) and at least one bump foil (3), wherein the top foil (2) and the bump foil (3) are constructed to overlap in a radial direction (9) and the foils (2, 3) form at least one arc segment (6) of the radial foil bearing (1) in a circumferential direction (10), wherein there is a first arc segment (6a) consisting of a first top foil (2a) and a first bump foil (3a) firmly connected to each other at a common end, A first arc segment (6a) is firmly arranged on a carrier foil (4), on which a second arc segment (6b) consisting of a second top foil (2b) and a second corrugated foil (3b) firmly connected to each other at a common end is arranged, and the two arc segments (6a, 6b) are placed successively on the carrier foil (4), so that when the carrier foil (4) is rolled up, a tubular carrier (7) with the two arc segments (6a, 6b) is produced and the radial foil bearing (1) is formed, It is characterized in that The carrier foil (4) has, in the unrolled state, at its boundary surface (19) extending in the longitudinal direction of the carrier foil (4), at least one tab (11) projecting from the boundary surface (19), the at least one tab being used as an orientation means for inserting the tubular carrier (7) at the correct angle after the carrier foil (4) has been rolled into the tubular carrier (7).

2. The tubular support (7) according to claim 1, characterized in that The at least one web (11) protrudes in a radial direction (8) beyond an axial dimension of the arc-shaped section (6).

3. A radial foil bearing (1) according to any one of the preceding claims, characterized in that The tubular carrier (7) is inserted into the outer ring (5).

4. The radial foil bearing (1) according to claim 3, characterized in that The at least one web (11) protrudes in an axial direction (8) beyond an axial dimension of the outer ring (5) which is defined by its end faces (16, 17).

5. The radial foil bearing (1) according to claim 4, characterized in that The at least one web (11) engages in a radial direction (9) in a corresponding receptacle (12) of the outer ring (5) which is provided for the at least one web (11).

6. The radial foil bearing (1) according to claim 5, characterized in that The receptacle (12) is recessed into the material at the end faces (16, 17) of the outer ring (5).

7. The radial foil bearing (1) according to claim 5 or 6, characterized in that: The receptacle (12) is recessed into the material on the outer side (18) of the outer ring (5).

8. The radial foil bearing (1) according to any one of claims 4 to 7, characterized in that One of the at least one web (11) engages in a radial direction (9) in a corresponding receptacle (12) of the outer ring (5) provided for the at least one web (11) and aligns the tubular support (7) in an angularly correct manner within the outer ring (5).

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