Radial foil bearing having carrier foil for fastening foil group to carrier foil by means of curved hooks

Abstract

The invention relates to a radial foil bearing (1) comprising at least one cover foil (2) and at least one corrugated foil (3), the cover foil (2) and the corrugated 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 a first arc-shaped section (6a) is present, which consists of a first cover foil (2a) and a first corrugated foil (3a) which are fixedly connected to one another at a common end (12a), the first arc-shaped section (6a) is fixedly arranged on the carrier foil (4), and a second arc-shaped section (6b) is arranged on the carrier foil (4), the invention relates to a radial foil bearing (1) comprising a carrier foil (4) having a second arc-shaped section (6a, 6b), which consists of a second cover foil (2b) and a second corrugated foil (3b), which are fixedly connected to one another at a common end (12b), and the two arc-shaped sections (6a, 6b) are placed on the carrier foil (4) so as to follow one another, such that when the carrier foil (4) is rolled up, a tubular carrier (7) having the two arc-shaped sections (6a, 6b) is produced and forms the radial foil bearing (1), wherein the fastening of the cover foil (2a, 3a) and the corrugated foil (2b, 3b) of the arc-shaped sections (6a, 6b) to the carrier foil (4), which is present in the unrolled state thereof, is formed by means of at least one web (11) of the carrier foil (4), which web surrounds the corresponding arc-shaped section (6a, 6b).

Description

Technical Field Background Art

[0001] Radial foil bearings are provided for aerodynamically supporting the shaft, wherein a load-bearing gas cushion is formed between the shaft and the radial foil bearing. The mode of operation is similar to that of a hydrodynamic plain bearing, but the difference is that the shaft is supported by the radial foil bearing via an air cushion and not by a liquid cushion as in a hydrodynamic plain bearing. The common point of both modes of operation is that the rotational movement of the shaft causes the formation of the 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. Due to these features, foil bearings, although less rigid than conventional air bearings, can nevertheless adapt to geometric air gap changes caused by misalignment errors, for example due to different thermal expansions of the bearing seat or shaft and housing, thereby achieving in practice a higher operational reliability in many applications.

[0003] In order to form a load-bearing air cushion, radial foil bearings usually have a cover foil in contact with the stationary shaft and a corrugated foil arranged radially between the cover foil and the outer ring of the bearing, which can be elastically compressed 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, whereby the foil bearing can be accommodated in a housing. The outer ring can also be formed in one piece by the 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 air present in the air gap defined by the stationary state is compressed. Starting from a certain rotational speed of the shaft, an air cushion is formed between the cover foil and the shaft, on which the shaft can slide. The foil pack with its corrugated foil and its radial spring action ensures that fluctuations in the air pressure or vibrations of the shaft in the radial direction do not damage the bearing, so that the air cushion remains load-bearing.

[0005] Foil bearings are known in the prior art in a variety of designs. In addition to radial foil bearings, there are also axial foil bearings that can be designed with axial load-bearing capacity. The arrangement of the foils of the bearings and their geometrical design are varied and are adapted to each application.

[0006] US 2015 / 292 552 A and US 2011 / 052 110 A respectively show the construction solutions of radial foil bearings. Summary of the invention

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

[0008] The radial foil bearing according to the present invention has a plurality of, preferably three, arcuate segments, wherein there is a first arcuate segment, which is composed of a first cover foil and a first corrugated foil fixedly connected to each other at a common end, wherein the first arcuate segment is fixedly arranged on a carrier foil, wherein a second arcuate segment is arranged on the carrier foil, wherein the second arcuate segment is composed of a second cover foil and a second corrugated foil fixedly connected to each other at a common end, wherein the two arcuate segments are placed one behind the other on the flat carrier foil, so that when the carrier foil is rolled up, a tubular carrier with two arcuate segments is produced and the tubular carrier constitutes a radial foil bearing.

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

[0010] The arcuate segments are formed by the cover foil and the corrugated foil which are fixedly connected to each other at the ends. The arcuate segments are then placed one behind the other on the carrier foil, wherein two arcuate segments following one another are spaced apart from one another, so that after rolling up the carrier foil which has been flattened out to form the tubular carrier, the ends of the arcuate segments either overlap to a small extent with the following ends of the following arcuate segments, abut one another, or are slightly spaced apart from one another. Thus, at least two arcuate segments are provided in order to characterize that the arcuate segments follow one another on the carrier foil, wherein for the function of the bearing, three arcuate segments following one another can advantageously be provided.

[0011] Here, the previously flat carrier foil is wound around the arcuate section so that the carrier foil wraps around the arcuate section. Thus, after forming the tubular carrier, the carrier foil follows the foils formed by the cover foil and the corrugated foil in the radial direction and abut against each other.

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

[0013] In order to reliably place and fasten the arc segment with the ends at which the two foils are connected to each other on the carrier foil, the carrier foil has a tab that can come into contact and / or align with the ends of the arc segment. Advantageously, the tab is formed at the edge of the strip-shaped carrier foil so that it is easily accessible for tools so that the tab can be bent over and the arc segment is fixed to the carrier foil.

[0014] This has the advantage according to the invention that the radial foil bearing can be inserted directly into a bearing receiving bore, for example a bearing receiving bore of a compressor housing, as an assembly consisting of an arc segment and a carrier foil, or can be connected as a self-retaining unit consisting of an arc segment and a carrier foil to a bearing outer ring sleeve which can then be installed in a complete set. In addition, welding the arc segment to the carrier foil can be omitted, thereby also eliminating the disadvantage of temperature input that causes warping.

[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 boosters or turbochargers, wherein the design according to the invention of the radial foil bearing allows for mass production that is as cost-effective as possible and furthermore provides the possibility of a modular construction in order to meet different requirements with regard to the realization of radial foil bearings in complete plant components.

[0016] Within the scope of the present invention, the carrier foil in an unrolled state has at least one web extending from the boundary surface at its boundary surface extending in the longitudinal direction of the carrier foil, and the web is bent over at the common end of the corrugated foil and the cover foil of the arc segment, so that it can be used as a fastening part for the arc segment.

[0017] In this case, the boundary surface is not the surface of the carrier foil on which the arcuate segments are fastened or placed. Rather, the boundary surface is the surface of the flatly unfolded carrier foil which, after the carrier foil is rolled up, forms a quasi-circular end surface of the tubular carrier. Thus, in the flatly unfolded state of the carrier foil, the boundary surface is directional with respect to the maximum length of the foil. Thus, the extension of the following boundary surface results in arcuate segments that follow one another.

[0018] Advantageously, a plurality of tabs are formed from the carrier foil. At least a single tab according to the invention of the carrier foil is already required. After the arc segment has been placed on the carrier foil, at least one tab surrounds the end of the arc segment. Alternatively, the tab according to the invention can be formed from one of the foils of the arc segment and surround the carrier foil after the tab has been successfully bent, so that the arc segment is firmly fixed on the carrier foil.

[0019] In an advantageous embodiment of the present invention, at least one web protrudes in the axial direction beyond the axial dimension of the arcuate section or the carrier foil before bending. After bending the web, no part of the web any longer exceeds the axial limiting dimension of the arcuate section or the carrier foil.

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

[0021] The tubular carrier is bent out / wrapped / curved from the state of a 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 maintained with the aid of an additional tool until the tubular carrier is pushed into the outer ring, or can be done without additional tools by selecting a material for the carrier foil that allows it to assume a plastic state.

[0022] In one embodiment of the invention, at least one web lies on a common end of the cover foil and the corrugated foil of the arc-shaped section.

[0023] Another embodiment of the present invention provides that each arc-shaped section is fastened to the carrier foil by two oppositely disposed webs.

[0024] In a development of the invention, orientation means are respectively provided on the carrier foil and the arc-shaped segment, which determine the position for fastening the arc-shaped segment to the carrier foil in an aligned manner with respect to one another.

[0025] In particular, each arc segment advantageously has two orientation means, which reliably align the arc segment to the carrier foil so that after the carrier foil has been rolled up with the arc segment fastened thereto into a tubular carrier, no part of the arc segment protrudes beyond the axial limiting dimension of the carrier foil. During the installation of the foil, a tool engages in the orientation means, which tool aligns the foils relative to one another—then at least one tab of the carrier foil is bent over, wherein the connection assumes the function of reliably aligning the foils relative to one another.

[0026] Alternatively, in one embodiment of the invention, each arc segment can be fastened to the carrier foil by means of two tabs, and the tabs reliably align the arc segment to the carrier foil, so that after the carrier foil is rolled up into a tubular carrier together with the arc segment fastened thereto, no part of the arc segment protrudes beyond the axial limiting dimension of the carrier foil, and no arc segment slides after rolling up, so that the function of the radial foil bearing is no longer guaranteed. Advantageously, the tabs for fastening are pre-bent in a certain position so that they engage in corresponding receptacles of the cover foil and the corrugated foil when the fastening is not yet completed. Only then are the tabs placed in the end position for fastening the foil in a loss-proof manner, and the fastening is then completed. In this alternative, a separate orientation mechanism can be omitted. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The advantageous embodiments of the present invention are described in detail in the following drawings. The drawings show:

[0028] Figure 1 In a first view, a flatly unfolded carrier foil is shown with a plurality of arc segments mounted thereon.

[0029] Figure 2 In the second view, the carrier foil is shown in the figure unfolded flatly.

[0030] Figure 3 shows the rolled-together carrier foil and the outer ring as a tubular carrier before joining,

[0031] Figure 4 A tubular carrier is shown joined into an outer ring to form a radial foil bearing,

[0032] Figure 5 The flatly unfolded carrier foil is shown as an individual component,

[0033] Figure 6 The corrugated foil is shown as a single component,

[0034] Figure 7 The cover foil is shown as a single component,

[0035] Figure 8 An arrangement for assembly with aligned individual components is shown in an exploded view, and

[0036] Fig. 9 A detail view showing the fastening of the arcuate segments to the carrier foil is shown. DETAILED DESCRIPTION

[0037] Figure 1In the first view, a flatly unfolded carrier foil 4 is shown with a plurality of arc segments 6 mounted thereon. After the carrier foil 4 is rolled into a tubular carrier 7, the carrier foil 4 has a main extension direction transverse to the subsequent axial direction 8. The arc segments 6 are triple present with 6a, 6b and 6c and are fastened to the carrier foil 4 following each other. After the carrier foil 4 is rolled into a tubular carrier 7, the arc segments already have a pre-bent profile consistent with the subsequent circumferential direction 10. Each arc segment 6a, 6b or 6c has a cover foil 2a, 2b or 2c and a corrugated foil 3a, 3b or 3c. The tabs 11 according to the present invention are composed of a single material of the carrier foil 4 and, for example, surround the common end 12a of the arc segment 6a. A plurality of tabs 11 exist in pairs so that the corresponding arc segments 6a, 6b or 6c are fastened to the carrier foil 4. The boundary surfaces 19 extend along the above-mentioned main extension direction and delimit the carrier foil 4 on both sides. The arcuate sections 6 are not arranged on the boundary surfaces 19; the boundary surfaces 19 form tabs 11 which, in the unbent state, extend from the extension of the corresponding boundary surface 19, as in Figure 5 As can be seen more clearly in .

[0038] Figure 2 In the second view, Figure 1 In addition to the flattened carrier foil Figure 1 In addition to the description, the corrugated foils 3a, 3b and 3c can be observed. The observation shows that each corrugated foil 3a, 3b and 3c has a central slit, however the slit does not divide the corrugated foil itself into two independent parts.

[0039] Figure 3 The rolled-up carrier foil 4 and the outer ring 5 are shown as a tubular carrier 7 before being joined to one another. By rolling up the carrier foil 4, the arcuate sections 6 are arranged one behind another in the circumferential direction 10 and form a functionally important part of the radial foil bearing 1. The tubular carrier 7 maintains its tubular shape itself or is retained by a tool not shown here. The outer ring 5 is to accommodate the tubular carrier 7 and protect the tubular carrier 7 from damage when the radial foil bearing 1 is inserted into the receiving opening of the housing. Firstly, the tubular carrier 7 and the outer ring 5 are aligned coaxially with respect to each other in alignment with the center axis 15, but at an axial spacing relative to each other. It can be clearly seen that the limiting surface 19 now forms a circle in its extension. The orientation means 13, 14, which are designed as circular openings, are arranged in Figure 8 The outer ring 5 has a receiving hole suitable for the tubular carrier 7 and is formed with an outer surface concentric with the receiving hole as a bottomless sleeve.

[0040] Figure 4The tubular carrier 7 engaging into the outer ring 5 is shown to form the radial foil bearing 1 . The radial foil bearing 1 is now present in a manner completed by means of the tubular carrier 7 engaging into the outer ring 5 .

[0041] Figure 5 The flatly unfolded carrier foil 4 is shown as an individual component. The webs 11 protrude from the boundary surface 19 delimiting the carrier foil 4 just as flatly as the carrier foil 4 is unfolded flatly. The boundary surface 19 extends along the main extension direction mentioned above and delimits the carrier foil 4 on both sides. The arc segments 6 are not arranged on the boundary surface 19, which forms the webs 11 and protrudes from the extension of the respective boundary surface 19. An orientation device 13 is arranged between two opposite webs 11, which are intended to fasten one of the arc segments to the carrier foil 4 at the same time, by means of which the arc segment to be mounted or its individual components can be aligned with the carrier foil 4.

[0042] Figure 6 A corrugated foil 3 is shown as a single component. Each corrugated foil 3 is pre-pressed into an arc and forms an arc segment together with a suitable cover foil. Here, the subsequent circumferential direction 10 has been predetermined. The corrugated foil 3 also has two orientation mechanisms 14, which are arranged at the common end 12 formed after the assembly with the suitable cover foil is completed. For the flexible functionality of the radial foil bearing during operation, the area around the common end 12 is not important. The area accommodates functional elements for fastening and alignment and is correspondingly non-flexibly configured. Therefore, there is a pair of recesses 16 in the area of ​​the common end 12 in the alignment portion of the orientation mechanism 14 at the edge side of the corrugated foil 3, and the tabs 11 of the carrier foil 4 can be engaged in this pair of recesses.

[0043] Figure 7 The cover foil 2 is shown as a separate component. Each cover foil 2 is pre-pressed into an arc and forms an arc segment together with a suitable corrugated foil. Here, the subsequent circumferential direction 10 has been predetermined. The cover foil 2 also has two orientation devices 14, which are arranged at the common end 12 formed after the assembly with the suitable corrugated foil. For the flexible functionality of the radial foil bearing during operation, the area around the common end 12 is not important. The area accommodates functional elements for fastening and alignment and is correspondingly non-flexibly configured. Therefore, there is a pair of recesses 17 in the area of ​​the common end 12 in the alignment portion of the orientation device 14 at the edge side of the cover foil 2, and the tabs 11 of the carrier foil 4 can be engaged in this pair of recesses.

[0044] Figure 8 The arrangement for assembly with aligned individual components is shown in the exploded view. The individual components are - according to Figure 5 - Carrier foil 4, - According to Figure 6 of - at least one corrugated foil 3 and - according to Figure 7 - at least one cover foil 2, wherein three pairs of cover foil 2 and corrugated foil 3 are present one after another and each pair is prepared to form an arc segment 6. In the following, the explanation is limited to one pair 2a and 3a to form an arc segment 6a, because each arc segment 6 is identical to each arc segment 6 and is only arranged in a plurality one after another on the carrier foil 4.

[0045] according to Figure 6 and Figure 7 , the cover foil 2a and the corrugated foil 3a have an orientation mechanism 14 and recesses 16, 17. The orientation mechanisms 14 of the two foils 2a, 3a overlap in that the cover foil 2a is placed above the corrugated foil 3a - the alignment above the orientation mechanisms 14, 13 is represented in the diagram by means of a narrow elongated cylinder, which itself does not form an independent component. At the same time, the orientation mechanisms 14 of the foils 2a, 3a overlap with the orientation mechanism 13 of the carrier foil 4. Each cylinder represented fictitiously here orients the orientation mechanism 14 of the cover foil 2a, the orientation mechanism 14 of the corrugated foil 3a and the orientation mechanism 13 of the carrier foil 4 in alignment with each other. This also ensures that the webs 11 can be joined into their corresponding recesses 17 and 16, which can also be linked via a stacked arrangement. After the foils 2 a , 3 a have been positioned, they lie against one another with their common end 12 and form an arc-shaped section 6 a standing upright on the carrier foil 4 .

[0046] Fig. 9 A detailed view of the fastening of the arc segment 6a to the carrier foil 4 is shown. Figure 8 As explained in , the arcuate section 6a is present in a manner supplemented by means of the cover foil 2a and the corrugated foil 3a, and the common end 12a rests on the carrier foil 4. The aligned arrangement of the orientation means 13, 14 can be clearly seen, which causes the recesses 16, 17 to also be aligned with each other, so that the corresponding webs 11 can be bent, can pass through the recesses 16, 17, and in the region of the common end 12a rest on the free surface of the cover foil 2a, at least the arcuate section 6a is secured to the carrier foil 4 in a captive manner.

[0047] Reference numerals list

[0048] 1 Radial foil bearing

[0049] 2 Covering foil

[0050] 2a First cover foil

[0051] 2b Second cover foil

[0052] 2c Third cover foil

[0053] 3 Corrugated foil

[0054] 3a First corrugated foil

[0055] 3b Second corrugated foil

[0056] 3c Third corrugated foil

[0057] 4 Carrier foil

[0058] 5 Outer Ring

[0059] 6 Ring sections

[0060] 6a First annular segment

[0061] 6b Second ring segment

[0062] 6c Third ring segment

[0063] 7 Tubular carrier

[0064] 8 Axial direction

[0065] 9 Radial direction

[0066] 10 Circumferential direction

[0067] 11. Splice

[0068] 12a Common end

[0069] 12b Common end

[0070] 12c Common end

[0071] 13 Orientation mechanism (carrier foil)

[0072] 14 Orientation mechanism (ring segment / corrugated foil / cover foil)

[0073] 15 Central axis

[0074] 16 Blank space (corrugated foil)

[0075] 17 Blank space (cover foil)

[0076] 18-

[0077] 19 limit interface

Claims

1. A radial foil bearing (1), comprising at least one cover foil (2) and at least one corrugated foil (3), wherein the cover foil (2) and the corrugated foil (3) are arranged one above the other 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), which is composed of a first cover foil (2a) and a first corrugated foil (3a) fixedly connected to each other at a common end (12a), and the first arc segment (6a) is connected to the first cover foil (2a) and the first corrugated foil (3a) fixedly connected to each other at a common end (12a). An arc segment (6a) is fixedly arranged on a carrier foil (4), a second arc segment (6b) is arranged on the carrier foil (4), the second arc segment is composed of a second cover foil (2b) and a second corrugated foil (3b) which are fixedly connected to each other at a common end (12b), and the two arc segments (6a, 6b) are placed one behind the other on the carrier foil (4), so that when the carrier foil (4) is rolled up, a tubular carrier (7) with two arc segments (6a, 6b) is produced and the tubular carrier forms the radial foil bearing (1), It is characterized in that The fastening of the cover foil (2a, 3a) and the corrugated foil (2b, 3b) of the arcuate segments (6a, 6b) to the carrier foil (4) in its unrolled state is formed by means of at least one web (11) of the carrier foil (4), which surrounds the corresponding arcuate segment (6a, 6b).

2. The radial foil bearing (1) according to claim 1, characterized in that The at least one web (11) protrudes in the axial direction (8) beyond the axial dimension of the arc-shaped segment (6) and subsequently fastens the arc-shaped segment (6a, 6b) in an enclosing manner by bending in opposite axial directions.

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. A radial foil bearing (1) according to any one of the preceding claims, characterized in that The at least one web (11) lies on a common end (12a, 12b) of the cover foil (2a, 2b) and the corrugated foil (3a, 3b) of the arc-shaped section (6a, 6b).

5. A radial foil bearing (1) according to any one of the preceding claims, characterized in that Each arc-shaped segment (6a, 6b) is fastened to the carrier foil (4) via two oppositely disposed webs (11).

6. A radial foil bearing (1) according to any one of the preceding claims, characterised in that Orientation means (13, 14) are respectively provided on the carrier foil (4) and the arcuate segments (6a, 6b), which determine positions for fastening the arcuate segments (6a, 6b) on the carrier foil (4) in an aligned manner.

7. The radial foil bearing (1) according to claim 6, characterized in that Each arcuate segment (6a, 6b) has two orientation mechanisms (13, 14), which reliably align the arcuate segments (6a, 6b) with the carrier foil (4), so that after the carrier foil (4) is rolled into the tubular carrier (7) together with the arcuate segments (6a, 6b) fastened thereto, no part of the arcuate segments (6a, 6b) protrudes beyond the axial limiting dimensions of the carrier foil (4).

8. A radial foil bearing (1) according to any one of the preceding claims, characterised in that Each arcuate segment (6a, 6b) is fastened to the carrier foil (4) by means of two tabs (11), and the tabs (11) reliably align the arcuate segments (6a, 6b) to the carrier foil (4), so that after the carrier foil (4) is rolled into the tubular carrier (7) together with the arcuate segments (6a, 6b) fastened thereto, no part of the arcuate segments (6a, 6b) protrudes beyond the axial limiting dimensions of the carrier foil (4).

9. A radial foil bearing (1) according to any one of the preceding claims, characterised in that At least one of the cover films (2a, 2b) is coated.

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