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EP-4411156-B1 - AIR FOIL JOURNAL BEARING

EP4411156B1EP 4411156 B1EP4411156 B1EP 4411156B1EP-4411156-B1

Inventors

  • CHO, JINWOO
  • HWANG, WOONG
  • KIM, KYEONG DONG

Dates

Publication Date
20260506
Application Date
20221005

Claims (13)

  1. An airfoil journal bearing comprising: a bearing housing (321, 721) having an inner circumferential surface forming a hollow (3211, 7211) through which a rotation shaft (311, 711) is insertable; and an airfoil (322, 622, 722, 822) that, when the rotation shaft is inserted through the hollow, is between the inner circumferential surface of the bearing housing and an outer circumferential surface of the rotation shaft, wherein the airfoil comprises: a first foil region (A1) that, when the rotation shaft is inserted through the hollow, extends in a circumferential direction (R) of the rotation shaft in a range from 180 to 360 degrees around the rotation shaft, the first foil region having a first airfoil edge in a first axial direction (A) of the rotation shaft and a second airfoil edge in a second axial direction of the rotation shaft that is opposite to the first axial direction, a pair of second foil regions (A2) that, when the rotation shaft is inserted through the hollow, extend in in the circumferential direction in a range from 180 to 360 degrees around the rotation shaft, each second foil region comprising a plurality of elastic bumps (4221, 6221A, 6221B, 7221, 8221) in the circumferential direction of the rotation shaft on a surface of the respective second foil region, wherein: a first of the second foil regions (A21) of the pair of second foil regions extends from the first airfoil edge of the first foil region and a second of the second foil regions (A21) of the pair of second foil regions extends from the second airfoil edge of the first foil region, the first foil region, the second foil regions, and the plurality of elastic bumps of each second foil region are integrally formed together as one body, the first foil region has a smooth curved surface and a first width (t11) parallel to the axial direction of the rotation shaft, the pair of second foil regions have a second width (t21) and a third width (t22), respectively, the second width and the third width each being parallel to the axial direction of the rotation shaft, characterised in that the first width is greater than each of the second width and the third width.
  2. The airfoil journal bearing of claim 1, wherein each of the elastic bumps of the plurality of elastic bumps of each second foil region has a protruding shape that, when the rotation shaft is inserted through the hollow, extends from the outer circumferential surface of the rotation shaft toward the inner circumferential surface of the bearing housing.
  3. The airfoil journal bearing of claim 2, wherein each of the elastic bumps of the plurality of elastic bumps (4221, 6221B, 7221, 8221) of each second foil region is formed by cutting at least some of the surface of the respective second foil region.
  4. The airfoil journal bearing of claim 2, wherein each of the elastic bumps of the plurality of elastic bumps (6221A) of each second foil region is formed by embossing a part of the respective second foil region.
  5. The airfoil journal bearing of claim 2, wherein the plurality of elastic bumps of each second foil region are formed by pressing the surface of the respective second foil region in certain areas while not pressing the surface in other areas such that in each respective second foil region, the pressed areas of the surface have a greater curvature than the other areas of the surface.
  6. The airfoil journal bearing of claim 1, wherein: the airfoil has a first airfoil edge (322A, 622A, 722A, 822A) extending along the circumferential direction of the airfoil, the first airfoil edge connected to the bearing housing as a fixed edge, and the airfoil has a second airfoil edge (322B, 622B, 722B, 822B) opposite to the first airfoil edge, the second airfoil edge being a free edge.
  7. The airfoil journal bearing of claim 6, wherein: the bearing housing includes an insert groove (3212, 7212) in the inner circumferential surface of the bearing housing, and the airfoil includes, at the first airfoil edge, a first insert part (3220, 6220, 7220) that extends outwardly from the airfoil toward the inner circumferential surface of the bearing housing and is inserted into the insert groove.
  8. The airfoil journal bearing of claim 7, wherein: when the rotation shaft (711) is inserted through the hollow (7211), the airfoil (722) encloses, at least once, the outer circumferential surface of the rotation shaft, and the airfoil includes, at the second airfoil edge (722B), a second insert part (7223) that is inserted into the insert groove (7212) through a hole (7224) in or near the first insert part (7220).
  9. The airfoil journal bearing of claim 1, wherein the first foil region and the second foil regions each have a length in the circumferential direction of the rotation shaft, wherein the respective lengths are substantially the same for the first foil region and the second foil regions.
  10. The airfoil journal bearing of claim 1, wherein, when the rotation shaft (711) is inserted through the hollow (7211), the first foil region and the pair of second foil regions extend at least 360 degrees around the outer circumferential surface of rotation shaft.
  11. The airfoil journal bearing of claim 1, wherein the airfoil further comprises: a coating layer comprising a polytetrafluoroethylene (PTFE) material coated on an inner surface of the first foil region facing the outer circumferential surface of the rotation shaft.
  12. The airfoil journal bearing of claim 1, wherein the first foil region includes a third foil region (A3) having a plurality of elastic bumps (8221) that, when the rotation shaft is inserted through the hollow, extend in the circumferential direction of the rotation shaft.
  13. The airfoil journal bearing of claim 1, wherein the airfoil is formed from a single member by processing the single member to form the plurality of elastic bumps in each second foil region, and rolling the processed single member in a circumferential direction.

Description

1. Field The disclosure relates to an airfoil journal bearing. 2. Description of Related Art A mechanical device, such as a vacuum cleaner and a compressor, may include a motor for rotating a rotor. The mechanical device may include a bearing for supporting rotation of a rotation shaft while constantly maintaining a position of the rotation shaft during operation of the motor. A bearing may fix a rotation shaft in a predetermined position and rotate the rotation shaft while supporting a load generated from rotation of the rotation shaft. There are various types of bearings, such as a ball bearing, a journal bearing, a foil bearing, and the like. An airfoil journal bearing may support a load in a radial direction perpendicular to an axial direction of the rotation shaft. An airfoil journal bearing may include an airfoil for forming a fluid layer on the outer surface of the rotation shaft, and the airfoil may support a load of the rotation shaft not in contact with the rotation shaft through pressure of the fluid layer. A typical airfoil journal bearing, after separately forming a bump foil and a top foil, may have a structure assembled by stacking the bump foil and the top foil and inserting the stacked bump and top foils inside a bearing housing. In a typical structure, the bump foil and the top foil may be in separate forms, and thus, each component may need to be separately assembled and mounted to the bearing housing. Therefore, components may not be effectively managed and problems may be caused by defective assembly. In addition, a foil may be inserted, in a stacked state, into the bearing housing, and thus, thickness of the inserted foil may increase. Recently, miniaturized mechanical devices have been in demand to satisfy the desires of consumers. The demand for miniaturized mechanical devices may require miniaturization of accessories, such as a motor and a bearing. Accordingly, technology for manufacturing components in a simplified structure has been developed to minimize manufacturing tolerance and resolve an issue of a narrow assembly space. US 2014/376844 A1 discloses a wing foil bearing including one or more tab foil layers comprising a thin material with an array of tab shapes. US 2019/368543 A1 discloses a hybrid foil bearing comprising a bump foil extending along an inner face of a first portion of a bearing sleeve and a metal mesh extending along an inner face of a second portion of the bearing sleeve. KR 102 230 226 B1 discloses an air foil journal bearing comprising a bump foil having elastic bumps of corrugation shapes and a bent unit where one end part in the circumferential direction is bent to the outside in a radial direction. SUMMARY According to an aspect of the invention, an air foil journal bearing is provided according to claim 1. BRIEF DESCRIPTION OF THE DRAWINGS The above and other aspects, features, and advantages of certain embodiments of the present disclosure will be more apparent from the following detailed description, taken in conjunction with the accompanying drawings, in which: FIG. 1 is a perspective view illustrating a mechanical device according to an example embodiment;FIG. 2A is a perspective view illustrating a motor assembly according to an example embodiment;FIG. 2B is an exploded perspective view illustrating the motor assembly according to an example embodiment;FIG. 2C is a cross-sectional view illustrating the motor assembly according to an example embodiment;FIG. 3A is a perspective view illustrating an airfoil journal bearing supporting a rotation shaft, according to an example embodiment;FIG. 3B is a cross-sectional perspective view illustrating an airfoil journal bearing according to an example embodiment;FIG. 4A is a diagram illustrating an unfolded airfoil according to an example embodiment;FIG. 4B is a diagram illustrating a rolled airfoil according to an example embodiment;FIG. 5A is a cross-sectional view illustrating a first foil region in an airfoil journal bearing viewed from the axial direction, according to an example embodiment;FIG. 5B is a cross-sectional view illustrating a second foil region in an airfoil journal bearing viewed from the axial direction, according to an example embodiment;FIG. 6A is a diagram illustrating an unfolded airfoil according to an example embodiment;FIG. 6B is a diagram illustrating an unfolded airfoil according to another example embodiment;FIG. 7A is a cross-sectional view illustrating an airfoil journal bearing according to an example embodiment;FIG. 7B is a diagram illustrating an unfolded airfoil according to another example embodiment;FIG. 8A is a diagram illustrating an unfolded airfoil according to another example embodiment; andFIG. 8B is a diagram illustrating a rolled airfoil according to another example embodiment. DETAILED DESCRIPTION Hereinafter, example embodiments will be described in detail with reference to the accompanying drawings. When describing the example embodiments with reference to the