GAS BEARING AND METHOD FOR PRODUCING SAME

Abstract

The invention relates to a gas bearing for contactlessly bearing a rotatable element (50). The gas bearing comprises: a housing (100) having an opening for receiving the rotatable element; and at least two sliding films (200), which are arranged on an interior (110) of the opening without overlap and which each have a first end portion (210) and a second end portion (220) for support on the housing (100). The sliding films (200) are designed to radially support the rotatable element relative to the housing (100) only by means of the first and second end portions (210, 220), the second end portion (220) providing frictional contact with the interior (110) and the first end portion (210) being fastened to the housing.

Claims

1. A gas bearing for supporting a rotatable element in a contact-free manner, comprising: a housing having an opening for receiving the rotatable element; and at least two sliding foils arranged without overlap on an inner side of the opening and each having a first end portion and a second end portion for support on the housing, wherein the sliding foils are configured to radially support the rotatable element relative to the housing only through the first and second end portions, wherein the second end portion provides frictional contact with the inner side and the first end portion is secured to the housing.

2. The gas bearing according to claim 1, wherein at least one of the sliding foils is formed multilayered and the individual layers are attached to the housing on a same side or on opposite sides.

3. A gas bearing for supporting a rotatable element in a contact-free manner, having the following features: a housing having an opening for receiving the rotatable element; and a plurality of multilayered sliding foils, wherein each multilayered sliding foil is arranged without overlapping an adjacent multilayered sliding foil on an inner side of the opening, and the individual layers of the multilayered sliding foils are all fixed to the housing with a first end portion, and the opposite second end portion forms a frictional contact with another layer of the multilayered sliding foil or with the housing; and wherein each layer of the multilayered sliding foils forms a circular segment in a radial section along a surface facing the rotatable element.

4. The gas bearing according to claim 3, wherein for increasing a coefficient of friction and/or friction work of the frictional contact at least one of the following features is formed: a coating of the second end portion and/or the inner side of the opening with a material that increases the coefficient of friction; the second end portion and/or the inner side of the opening comprises an increased roughness; the second end portion comprises a contour; the second end portion is angled in a radial cross-sectional view to form an increased contact angle for frictional contact relative to the inner side of the opening.

5. The gas bearing according to claim 3, wherein the opening in the housing deviates from a circular shape to increase a contact angle to the inner side compared to the circular shape.

6. The gas bearing according to claim 3, wherein, to increase the stiffness of at least one sliding foil, a thickness of the sliding foil varies between the first end portion and the second end portion to increase the supporting effect for radially acting forces.

7. The gas bearing according to claim 3, wherein the attachment of the first end portion to the housing comprises at least one of the following connections: a soldered connection, a welded connection, an adhesive connection, an at least partial insertion of the first end portion into a recess of the housing.

8. A rotor suspension, comprising: the gas bearing according to claim 3; and a rotatable element insertable into the opening of the housing such that sliding foils are arranged between the rotatable element and the housing to receive forces acting radially on the rotatable element relative to the housing and to form an air cushion with increasing rotational speeds.

9. The rotor suspension according to claim 8, wherein the at least two sliding foils are exchangeable, in order to select the at least two sliding foils with respect to their stiffness and depending on the rotatable element and the expected radial impacts.

10. A method for manufacturing a gas bearing for supporting a rotatable element in a contact-free manner, comprising: providing a housing having an opening for receiving a rotatable element; arranging at least two sliding foils extending in an arc-shaped manner single- or multilayered between a first end portion and a second end portion on an inner side of the opening without adjacent sliding foils overlapping, wherein relative to the housing the first end portion is tangentially immovable and the second end portion provides a frictional contact with the housing or another layer of a multilayered sliding foil; and inserting the rotatable element into the opening so that the at least two sliding foils are disposed between the rotatable element and the housing.

11. The method according to claim 10, wherein arranging the sliding foils comprises fixedly attaching the sliding foils to the housing or forming a releasable connection to the housing.

12. The gas bearing according to claim 1, wherein for increasing a coefficient of friction and/or friction work of the frictional contact at least one of the following features is formed: a coating of the second end portion and/or the inner side of the opening with a material that increases the coefficient of friction; the second end portion and/or the inner side of the opening comprises an increased roughness; the second end portion comprises a contour; the second end portion is angled in a radial cross-sectional view to form an increased contact angle for frictional contact relative to the inner side of the opening.

13. The gas bearing according to claim 1, wherein the opening in the housing deviates from a circular shape to increase a contact angle to the inner side compared to the circular shape.

14. The gas bearing according to claim 1, wherein, to increase the stiffness of at least one sliding foil, a thickness of the sliding foil varies between the first end portion and the second end portion to increase the supporting effect for radially acting forces.

15. The gas bearing according to claim 1, wherein the attachment of the first end portion to the housing comprises at least one of the following connections: a soldered connection, a welded connection, an adhesive connection, an at least partial insertion of the first end portion into a recess of the housing.

16. A rotor suspension, comprising: the gas bearing according to claim 1; and a rotatable element insertable into the opening of the housing such that sliding foils are arranged between the rotatable element and the housing to receive forces acting radially on the rotatable element relative to the housing and to form an air cushion with increasing rotational speeds.

17. The rotor suspension according to claim 16, wherein the at least two sliding foils are exchangeable, in order to select the at least two sliding foils with respect to their stiffness and depending on the rotatable element and the expected radial impacts.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0037] The exemplary embodiments of the present invention will be better understood on the basis of the following detailed description and the accompanying drawings of the different exemplary embodiments, which should, however, not be understood such that they limit the disclosure to the specific embodiments, but rather they merely serve for explaining and understanding.

[0038] FIG. 1 shows an air bearing according to an embodiment of the present invention.

[0039] FIGS. 2A-2D illustrate embodiments of the present invention that achieve a desired stability against radial impacts of the rotatable element relative to the housing by adjusting the frictional contact.

[0040] FIGS. 3A-3C show further embodiments of the sliding foils used.

[0041] FIGS. 4A-4D show embodiments for attaching the first end portion of the single- or multilayered sliding foils to the housing.

DETAILED DESCRIPTION

[0042] FIG. 1 shows an air bearing for supporting a rotatable element (in particular a high-speed rotor) in a contact-free manner according to an embodiment of the present invention. The air bearing comprises a housing 100 having an opening for receiving the rotatable element 50 and at least two sliding foils 200 (preferably three or four) arranged without overlap in a tangential direction on an inner side 110 of the opening. The sliding foils 200 are arc-shaped (not wave-shaped) and each comprise a first end portion 210 and a second end portion 220 for support on the housing 100. The sliding foils 200 are configured to radially support the rotatable element 50 relative to the housing 100 only through the first end portion 210 and the second end portion 220, wherein the rotatable element 50 contacts the sliding foil 200, for example, between the first end portion 210 and the second end portion 220.

[0043] The second end portion 220 provides frictional contact with the inner surface 110 of the opening and is thus movable relative to the housing. The first end portion 210 may be fixedly attached to the housing 100, or in positive contact with the housing 100 (e.g., engaging a groove or recess in the housing, see FIGS. 4A and 4B below; more complex attachments, e.g., L-shaped or T-shaped, are also conceivable, see FIGS. 4C and 4D below), such that relative movement along the inner surface 110 is not possible.

[0044] It will be appreciated that as long as the rotatable element 50 is not yet rotating relative to the housing 100, the rotatable element 50 is in contact with at least one (or all) of the sliding foils 200. However, as the rotational speed 50 increases, air is entrained between the sliding foils 200 and the rotatable element 50, forcing the sliding foils 200 away from the rotatable element 50 and creating an air cushion between the sliding foils 200 and the rotatable element 50. The adhesion of the air to the rotatable element 50 thus creates an air film or air cushion at very high speeds so that the rotatable element 50 lifts off the sliding foils 200. Typically, this effect only occurs at several 10,000 rpm or more than 100,000 rpm. These air bearings can be used, for example, for rotations of up to 200,000 rpm.

[0045] In order to provide reliable damping protection for impacts or radial movements of the rotatable element, the properties of the sliding foils 200, such as a prestress or geometries or the coupling to the housing 100, are important and must be set according to the application.

[0046] In the following, various measures are described that can be implemented in embodiments to achieve the desired damping protection.

[0047] FIGS. 2A to 2D show embodiments of the present invention that achieve a desired stability against radial impacts of the rotatable element 50 relative to the housing 100 by adjusting the frictional contact. For example, a high coefficient of friction between the sliding foil 200 and the housing 100 means that the sliding foils 200 are better able to dampen radial impacts, as higher friction makes it difficult for the sliding foils 200 to move relative to the housing 100.

[0048] In FIG. 2A, an embodiment is shown in which the second end portion 220 has, for example, a coating 221 that has the effect of increasing the coefficient of friction with respect to the housing 100. Similarly, it is possible for the inner side 110 of the housing to have a coating 111 that increases the coefficient of friction between the sliding foil 200 and the housing 100. The two coatings 221, 111 may also be matched to each other so as to achieve the highest possible friction or matched. The same effect can be achieved if an increased roughness of the surface is formed in the area of the coatings 111, 221.

[0049] FIG. 2B shows an embodiment of the sliding foils 200 in which the second end portions 220 have a surface structure/contour 222 adapted to increase friction between the sliding foil 200 and the inner side 110. For example, the surface structure 222 may include wave-shaped sections, indentations, tooth-like protrusions, or other structures that result in an increase in friction. It is also possible for the sliding foil 200 to be suitably thin, so that a sharp edge is formed at the end, resulting in high contact pressure and thus high friction.

[0050] FIG. 2C shows an embodiment of the present invention in which the second end portion 220 is angled relative to the remaining portion of the sliding foil 200. This results in the end of the sliding foil 200 forming a larger contact angle α with the inner side 110. The greater the contact angle α, the greater the force component acting perpendicularly on the inner side 110 during a radial impact. The contact angle can also be used to set the friction path. The vertical force component is relevant for the frictional force, so that the frictional force can be adjusted via an adapted chamfer of the second end portion 220.

[0051] FIG. 2D shows another embodiment of the air bearing in which the opening in the housing 100 is not circular—even though the rotatable element 50 still has a circular cross-section. According to this embodiment, the opening in the housing 100 is changed such that the intersection angle α between the second end portion 220 and the inner side 110 becomes larger or is adjusted to a desired value in order to change, in particular increase, the frictional force (or the force component essential thereto) or the frictional path compared to a circular opening.

[0052] Thus, the embodiments of FIGS. 2A to 2D can be used to adjust (especially increase) the coefficient of friction.

[0053] FIGS. 3A to 3C show further exemplary embodiments of the sliding foils 200, 300 used, which can also be used to better cushion radial impacts.

[0054] For this purpose, the exemplary embodiment of FIG. 3A uses sliding foils 300 having a plurality of layers, wherein all layers of the sliding foil 300 are arranged on top of each other and are fixed to the housing 100 on the same side, as an example, i.e., the first end portions 310 of the layers are all located on the same side along the tangential direction.

[0055] In FIG. 3B, an exemplary embodiment is shown in which at least one of the sliding foils 300 has multiple layers, wherein the individual layers are fixedly connected here to the housing 100 on opposite sides. Two layers are shown as an example. However, there can also be more than two layers, which are attached to the housing arbitrarily (e.g. alternately) on one side or the other (with respect to the tangential direction). The friction between the layers can in turn be adjusted via coating and/or a surface roughness.

[0056] FIG. 3C shows an exemplary embodiment of the present invention in which at least one sliding foil 200, 300 (singlelayered or multilayered) has a variable thickness so as to better cushion the radial impacts of the rotatable element 50 without the sliding foil 200, 300 coming into contact with the inner side 110 in a region between the end portions.

[0057] Only one sliding foil 200, 300 was shown here at a time. The other sliding foils were omitted for simplicity. They can be formed in a similar way. Combinations of the different sliding foils 200, 300 are also possible.

[0058] Furthermore, in these exemplary embodiments, the first end portions 210, 310 may be connected to the housing 100 by, for example, a welded contact, an adhesive contact, a soldered contact. It is also possible to slide the first end portions 210, 310 into corresponding grooves in the housing or to use rivet or screw connections as fasteners.

[0059] FIGS. 4A to 4D show embodiments for attaching the first end portion 210, 310 of the single- or multilayered sliding foils 200, 300 to the housing 100. In the exemplary embodiments shown, the first end portions 210, 310 of the sliding foils 200, 300 engage corresponding recesses, grooves, or indentations of the housing 100 to provide a firm hold of the sliding foils 200, 300 (or layers thereof) to the housing.

[0060] Here, there are various ways to form the recess in the housing 100. For example, it is possible for a circular recess to be formed as shown in FIG. 4A. Optionally, a square or quadrangular shape can also be selected, as shown in FIG. 4B. FIG. 4C shows an embodiment with an L-shaped engagement, and FIG. 4D shows an example of a T-shaped engagement with the housing 100. For both exemplary embodiments, the sliding foil 200, 300 can be inserted into the recess in the axial direction. After insertion, the sliding foil 200, 300 can be fixed accordingly (e.g. via a locking device). These recesses offer the advantage that the sliding foils 200, 300 can be easily exchanged, so that the sliding foils 200, 300 can be specifically selected according to the requirements.

[0061] Advantages of exemplary embodiments of the present invention can be summarized as follows: [0062] Bump foils, as used in conventional air bearings, can be omitted. Instead, single- or multilayered films 200, 300 are used. This makes production easier and saves costs. [0063] The bearing function is provided solely by a modified sliding foil 200, 300, wherein the modification is achieved by effectively increasing the rigidity of the foils. [0064] Similarly, the foils 200, 300 may be prestressed and thus pressed into the corresponding opening of the housing. This allows larger radial impacts to be absorbed. [0065] Damping of radial movements can be achieved by adjusting the friction between the foil 200, 300 and the housing 100. [0066] A defined interaction of the individual components results in better predictability.

[0067] The features of the invention disclosed in the description, the claims and the figures may be essential for implementing the invention both individually and also in any combination.

LIST OF REFERENCE NUMERALS

[0068] 50, 520 rotatable element/rotor
100 housing with opening
110 inner side of the opening
111, 221 coatings
200, 300 sliding foils (singlelayered or multilayered)
210, 310 first end portion of the sliding foils or of their layers
220, 320 second end portion of the sliding foils or of their layers
222 edge contours of the end portions
510 conventional housing
530 conventional top foils
540 conventional bump foils
532 foil attachment
α angle of impact of the second end portion on the housing