Thrust air bearing

Abstract

The present disclosure relates to a thrust air bearing supporting a rotating shaft, which has a plurality of foil units arranged in a ring shape, the foil unit having: a top foil portion; and a wave foil portion provided integrally with the top foil portion and arranged on the opposite side of the top foil portion in the circumferential direction forming the ring shape, the foil units being arranged so that the top foil portion overlaps the wave foil portion of the adjacent other foil unit.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a thrust air bearing. BACKGROUND

[0002] One example of a thrust air bearing is described in Patent Literature 1. This thrust air bearing is provided with a plurality of wave foils arranged at equal intervals on a thrust surface, and is also provided with a top foil arranged so as to overlap the wave foils. The wave foils and the top foil are individually fixed to the thrust surface by welding or the like.

[0003] Patent Literature 1: Japanese Patent Application Laid-Open No. 63-195412

[0004] In the conventional thrust air bearing, after the wave foils and the top foil are accurately positioned at prescribed positions, the wave foils and the top foil need to be individually welded or the like. Therefore, the installation of the wave foils and the top foil requires skill, and the yield can also be poor, which is not conducive to efficient manufacturing. SUMMARY

[0005] The present disclosure describes a thrust air bearing in which the installation of wave foils and a top foil is easy compared to a case in which the wave foils and the top foil are individually installed.

[0006] One embodiment of the present disclosure is a thrust air bearing that supports a rotating shaft, and is provided with a plurality of foil units arranged in a ring shape. The foil unit is provided with a top foil portion, and a wave foil portion that is provided integrally with the top foil portion and is arranged on the opposite side of the top foil portion in the circumferential direction in which the ring shape is formed. The foil units are arranged so that the top foil portion overlaps the wave foil portion of an adjacent other foil unit.

[0007] According to several embodiments of the present disclosure, the installation of the wave foil portion and the top foil portion becomes easy. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 is a cross-sectional view showing one example of a rotating machine provided with the thrust air bearing of the embodiment.

[0009] Figure 2 is a plan view of the thrust air bearing of the embodiment.

[0010] Figure 3 is a cross-sectional view along the line III-III of Figure 2

[0011] Figure 4 is a part of the thrust air bearing, and (a) is a perspective view showing a foil fixing portion, and (b) is a perspective view showing a foil unit.

[0012] Figure 5 is a perspective view of a base plate.

[0013] Figure 6 ​is an exploded perspective view showing a portion of a thrust air bearing.

[0014] Figure 7 is a sectional view showing a thrust air bearing provided in a rotary machine, (a) is a sectional view showing a portion of the thrust air bearing in an enlarged manner, and (b) is a sectional view taken along the line b-b of (a).

[0015] Figure 8 is a perspective view showing a base plate of a thrust air bearing according to another embodiment. DETAILED DESCRIPTION

[0016] One embodiment of the present disclosure is a thrust air bearing that supports a rotary shaft, and includes a plurality of foil units arranged in a ring shape. Each foil unit includes a top foil portion and a wave foil portion that is provided integrally with the top foil portion and is arranged on the opposite side of the top foil portion in the circumferential direction in which the ring shape is formed. The foil units are arranged such that the top foil portions overlap the wave foil portions of adjacent other foil units.

[0017] In one example, the thrust air bearing includes a plurality of foil units, and the top foil portion and the wave foil portion of each foil unit are provided integrally. That is, by mounting one foil unit, the top foil portion and the wave foil portion can be mounted without being misaligned. Further, by arranging the plurality of foil units while aligning them, the provision of all the top foil portions and the wave foil portions is completed. As a result, compared to a case in which the wave foil and the top foil are separately mounted, the mounting of the wave foil and the top foil becomes easy.

[0018] In some examples, a ring-shaped base plate that fixes the plurality of foil units and a foil fixing portion that fixes the foil units to the base plate can be further included. The foil unit can further include a fixing receiving portion that is provided between the top foil portion and the wave foil portion and is mounted to the base plate by the foil fixing portion.

[0019] In some examples, the foil unit can be mounted to the base plate in a detachable manner. In a case in which a failure occurs in the foil unit, the foil unit in which the failure has occurred can be removed from the base plate, and a new foil unit can be easily replaced.

[0020] In some examples, a positioning groove that accommodates the fixing receiving portion can be provided in the base plate, and the positioning groove can be provided so as to extend in the radial direction of the ring-shaped base plate. The fixing receiving portion can include a fitting protrusion that is fitted into the positioning groove and a receiving recess that receives the foil fixing portion on the opposite side of the fitting protrusion. The plurality of foil units need to be arranged in the circumferential direction as appropriate. The foil unit is positioned by the fixing receiving portion that is accommodated in the positioning groove, and the positioning groove is provided so as to extend in the radial direction of the ring-shaped base plate. As a result, the positional misalignment of the foil unit in a direction that intersects the radial direction, for example, in the circumferential direction, is suppressed.

[0021] In some examples, the bottom plate can also have an outer periphery and an inner periphery on the opposite side of the outer periphery in the radial direction. The positioning groove can be formed in a tapered shape in which the width in the circumferential direction of the bottom plate expands from an inner end portion near the inner periphery to an outer end portion near the outer periphery. The fitting protrusion can be formed in a tapered shape that fits into the tapered shape of the positioning groove, and is crimped to the positioning groove by the foil fixing portion. The fixing receiving portion has the fitting protrusion that fits into the tapered shape of the positioning groove in the radial direction, and the fitting protrusion is fitted into the tapered shape of the positioning groove. Therefore, when the fitting protrusion is crimped to the positioning groove by the foil fixing portion, the position is corrected at an appropriate position by the cooperation of the tapered shape of the fitting protrusion and the tapered shape of the positioning groove, and the positional deviation in the radial direction can be suppressed.

[0022] In some examples, the positioning groove can also have a bottom portion and a pair of side portions that stand from the bottom portion and are opposed in the circumferential direction. The pair of side portions can have a pair of inclined surfaces that are inclined in a manner such that the width in the circumferential direction expands the farther away from the bottom portion. The fitting protrusion can be inclined in a manner that fits into the pair of inclined surfaces, and is crimped to the inclined surfaces by the foil fixing portion. The inclined surfaces of the positioning groove are respectively provided at the pair of side portions that are opposed in the circumferential direction, and the fitting protrusion is inclined in a manner that fits into the pair of inclined surfaces. Therefore, when the fitting protrusion is crimped to the positioning groove by the foil fixing portion, the position is corrected at an appropriate position by the cooperation of the inclination of the fitting protrusion and the inclined surfaces of the positioning groove, and the positional deviation in the circumferential direction can be suppressed.

[0023] In some examples, the positioning groove can also have a bottom portion, and a gap between the bottom portion and the fitting protrusion, the gap extending in the radial direction. The gap can form a cooling flow path through which air can pass, and as a result, a heat dissipation function can be exerted.

[0024] In some examples, a bulging portion can be provided in the positioning groove, the bulging portion forming a gap region by being separated from the fitting protrusion in the circumferential direction. In the case where the fitting protrusion needs to be pulled out, the gap region is formed to make it easy to pull out.

[0025] In some examples, the bottom plate can also have an outer periphery and an inner periphery on the opposite side of the outer periphery in the radial direction. The positioning groove can have an insertion opening that is open at the outer periphery, and the fitting protrusion can be inserted from the insertion opening. The foil unit needs to be arranged such that the top foil portion overlaps the wave foil portion of another foil unit. As long as the above-described arrangement is made, the fitting protrusion of the foil unit can be inserted from the side that does not interfere with another foil unit and installed in the insertion opening, and thus the assembly of the thrust air bearing becomes easy.

[0026] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In addition, in the description of the drawings, the same reference numerals are attached to the same elements, and repetitive descriptions are omitted.

[0027] Figure 1An example of a rotating machine 1, such as an electric turbocharger, is shown. The rotating machine 1 has a turbine 2 and a compressor 3, and has an electric motor 5 that drives a rotating shaft 6 between the turbine 2 and the compressor 3. The turbine 2 has a turbine wheel 22 disposed in a turbine casing 21. The compressor 3 has a compressor wheel 32 disposed in a compressor casing 31. A motor casing 4 is disposed between the turbine casing 21 and the compressor casing 31, and the motor casing 4 has a stator 51 of the electric motor 5 fixed thereto.

[0028] The turbine wheel 22 is fixed to the rotating shaft 6 at the compressor wheel 32. Rotation of the turbine wheel 22 is transmitted to the compressor wheel 32 via the rotating shaft 6, and the compressor wheel 32 is driven in cooperation with the electric motor 5. The rotating shaft 6 has a rotor 52 fixed thereto that assists rotation of the rotating shaft 6 by cooperating with the stator 51. The rotating shaft 6 is rotatably supported by a plurality of bearings, at least one of which is a thrust air bearing 7 of an embodiment of the present disclosure. The configuration in which the rotating shaft 6 is supported by the thrust air bearing 7 is described.

[0029] The rotating shaft 6 has a thrust ring 61 disposed in a manner extending in a radial direction. In the present disclosure, the thrust ring 61 is disposed between the rotor 52 and the compressor wheel 32. The thrust ring 61 is disposed in a manner sandwiched between a pair of thrust air bearings 7. The thrust air bearings 7 have bearing surfaces 7a opposite the thrust ring 61, and back surfaces 7b opposite the bearing surfaces 7a with respect to the thrust ring 61 (see FIG. (a)). Figure 7

[0030] The pair of thrust air bearings 7 are arranged in a direction of an axis L of the rotating shaft 6. The pair of thrust air bearings 7 have a spacer 81 disposed therebetween for forming a gap that accommodates the thrust ring 61. The pair of thrust air bearings 7 are fastened together by a plurality of fastening bolts 82 in a manner sandwiching the spacer 81. The plurality of fastening bolts 82 are disposed at equal intervals in a circumferential direction CD of the thrust air bearings 7. The thrust air bearings 7 rotatably support the rotating shaft 6, respectively. In addition, the pair of thrust air bearings 7 cooperate to form an axial support configuration 70 that inhibits the thrust ring 61 from being displaced in the direction of the axis L.

[0031] In the following description, one of the pair of thrust air bearings 7, such as the thrust air bearing 7 closer to the rotor 52, is referred to as a first thrust air bearing 7, and the thrust air bearing 7 closer to the compressor wheel 32 is referred to as a second thrust air bearing 7. The back surface 7b of the first thrust air bearing 7 is supported by a member that forms the motor casing 4, and is positioned at a prescribed position (see FIG. (b)). Figure 7 ​The second thrust air bearing 7 is supported by a portion of a member that forms a portion of the compressor housing 31, and is positioned at a prescribed position. The first thrust air bearing 7 and the second thrust air bearing 7 have substantially the same configuration, and therefore, the first thrust air bearing 7 will be described as a representative.

[0032] As shown in FIG. 1, the thrust air bearing 7 has a ring-shaped bottom plate 71 that serves as a base, a plurality of foil units 9 mounted to the bottom plate 71, and a foil fixing portion 10 that fixes the foil units 9 to the bottom plate 71. A surface of the bottom plate 71 on which the plurality of foil units 9 are provided serves as a bearing surface 7a that opposes the thrust ring 61, and the opposite surface serves as a back surface 7b. Figure 2 Figure 3 As shown in FIG. 1, the thrust air bearing 7 has a ring-shaped bottom plate 71 that serves as a base, a plurality of foil units 9 mounted to the bottom plate 71, and a foil fixing portion 10 that fixes the foil units 9 to the bottom plate 71. A surface of the bottom plate 71 on which the plurality of foil units 9 are provided serves as a bearing surface 7a that opposes the thrust ring 61, and the opposite surface serves as a back surface 7b. Figure 6

[0033] The bottom plate 71 (see FIG. 2) is ring-shaped (annular), and has a substantially circular central hole CH through which the rotating shaft 6 is inserted. In the present disclosure, the radial direction RD of the bottom plate 71 refers to both the centrifugal direction and the direction opposite the centrifugal direction in a state in which the rotating shaft 6 is assumed to be inserted into the central hole CH with the axis L of the rotating shaft 6 as the center. For example, the radial direction RD refers to the direction orthogonal to the axis L. In addition, the circumferential direction CD of the bottom plate 71 refers to the direction in which the rotating shaft 6 rotates. In the present disclosure, it can be assumed that the outer shape of the bottom plate 71 is substantially circular. Therefore, the radial direction RD of the bottom plate 71 can also be described as the radial direction of the bottom plate 71, and the circumferential direction CD of the bottom plate 71 can also be described as the direction along the substantially circular outer shape of the bottom plate 71. Figure 5 The bottom plate 71 has an outer periphery 71a that forms a substantially circular outer shape, and an inner periphery 71b that is on the opposite side of the outer periphery 71a in the radial direction RD and that forms the central hole CH. The bottom plate 71 can be grasped as being divided into two regions in the radial direction RD, and for example, has an outer region 71x that is ring-shaped including the outer periphery 71a, and an inner region 71y that is ring-shaped including the inner periphery 71b. A step difference can also be formed between the outer region 71x and the inner region 71y. In the present disclosure, a step difference that falls from the outer region 71x into the inner region 71y is formed in the bearing surface 7a. A plurality of through holes 71c through which the fastening bolts 82 (see FIG. 3) are inserted are provided in the outer region 71x of the bottom plate 71. The plurality of foil units 9 are arranged in the inner region 71y of the bottom plate 71 in the circumferential direction CD.

[0034] Figure 1 A plurality of positioning grooves 72 and a plurality of through holes 73 for positioning the foil units 9 are provided in the inner region 71y of the bottom plate 71. The through holes 73 are formed so as to penetrate from the back surface 7b of the bottom plate 71 to the bottom portion 72a of the positioning grooves 72. The headless screws 19 (fastening portions) that fix the foil units 9 are inserted through the through holes 73 (see FIG. 4).

[0035] A plurality of positioning grooves 72 and a plurality of through holes 73 for positioning the foil units 9 are provided in the inner region 71y of the bottom plate 71. The through holes 73 are formed so as to penetrate from the back surface 7b of the bottom plate 71 to the bottom portion 72a of the positioning grooves 72. The headless screws 19 (fastening portions) that fix the foil units 9 are inserted through the through holes 73 (see FIG. 4). Figure 3 ​​​) is formed on the back surface 7b side of the through-hole 73. The head part 19a of the countersunk screw 19 is housed in the counterbore 71d. The countersunk screw 19 is inserted from the back surface 7b toward the through-hole 73.

[0036] The foil unit 9 (refer to Figure 4 Fig. (b) and Figure 6 ) is leaf-shaped (plate-shaped) having flexibility. In plan view, the inner region 71y of the bottom plate 71 is annular (circular ring-shaped). In plan view, the foil unit 9 is a shape in which the inner region 71y is equally divided in the circumferential direction CD. In addition, in the following description, the circumferential direction CD of the foil unit 9 refers to a direction substantially the same as the circumferential direction CD of the bottom plate 71, assuming that it is provided to the bottom plate 71. The foil unit 9 has a top foil part 91 on one side in the circumferential direction CD and a wave foil part 92 on the opposite side from the top foil part 91. In addition, a fixed receiving part 93 is provided between the top foil part 91 and the wave foil part 92. The fixed receiving part 93 integrally connects the top foil part 91 and the wave foil part 92.

[0037] The fixed receiving part 93 has a fitting protrusion 94 that is bent so as to protrude with respect to the top foil part 91 and the wave foil part 92. The fitting protrusion 94 is of a size and shape that is housed in the positioning groove 72 of the bottom plate 71. The foil unit 9 is positioned at a prescribed position of the bottom plate 71 by fitting the fitting protrusion 94 into the positioning groove 72. In the fixed receiving part 93, a receiving recess 95 into which the foil fixing part 10 is fitted is formed on the back surface side of the fitting protrusion 94, that is, on the opposite side of the fitting protrusion 94. In addition, a link hole 93a through which the shaft part 19b of the countersunk screw 19 is inserted is formed in the bottom plate part 93b that is the bottom of the receiving recess 95.

[0038] The foil fixing part 10 (refer to Figure 4 Fig. (a) and Figure 6 ) is of a size and shape that is housed in the receiving recess 95 and substantially fits into the receiving recess 95. A screw hole 11 into which the shaft part 19b of the countersunk screw 19 is screwed is formed in the foil fixing part 10. By screwing and fastening the countersunk screw 19 to the foil fixing part 10, the foil fixing part 10 is crimped to the receiving recess 95, sandwiching the fixed receiving part 93 between the receiving recess 95 and the positioning groove 72.

[0039] As shown in Figure 2 , a plurality of foil units 9 are arranged equally in the circumferential direction CD in the inner region 71y of the bottom plate 71 and are arranged as a whole so as to cover all or a part of the annular inner region 71y. If described specifically, the top foil part 91 of one foil unit 9 is arranged so as to overlap the wave foil part 92 of an adjacent other foil unit 9. In the present disclosure, for example, six (a plurality of) foil units 9 are arranged in an annular arrangement.

[0040] As shown in Figure 3 and Figure 6As shown, the wave foil portion 92 is a corrugated plate portion in cross section, and is arranged in a manner so as to follow the surface of the inner region 71y of the bottom plate 71. The top foil portion 91 is arranged on the wave foil portion 92. The top foil portion 91 is inclined in a manner so as to separate from the wave foil portion 92 at the front end portion 31b than the root portion 91a connected to the fixed receiving portion 93. In a case where one foil unit 9 provided to the bottom plate 71 is taken as a reference, the position of the wave foil portion 92 in the circumferential direction CD is on the front side in the rotation direction of the rotation shaft 6. In contrast, the position of the top foil portion 91 in the circumferential direction CD is on the rear side in the rotation direction.

[0041] Next, the positioning groove 72 of the bottom plate 71, the fixed receiving portion 93 of the foil unit 9, and the shapes of the foil fixing portion 10, and the fitting relationship will be described in further detail with reference to Figures 3-6

[0042] The bottom plate 71 is provided with a plurality of positioning grooves 72 in the same number as the set number of the foil units 9. The positioning groove 72 is provided in a manner so as to extend in the radial direction RD (centrifugal direction) of the annular bottom plate 71. The plurality of positioning grooves 72 are arranged at equal intervals in the circumferential direction CD. The positioning groove 72 has an inner end portion 72c close to the inner periphery 71b of the bottom plate 71, and an outer end portion 72d located on the opposite side in the radial direction RD from the inner end portion 72c and close to the outer periphery 71a of the bottom plate 71. In addition, the inner end portion 72c of the present disclosure reaches the inner periphery 71b of the bottom plate 71 and is open. The outer end portion 72d of the present disclosure reaches the boundary between the inner region 71y and the outer region 71x of the bottom plate 71. The positioning groove 72 is configured so that, in a plan view, the width of the outer end portion 72d is greater than the width of the inner end portion 72c, and becomes tapered in which the width in the circumferential direction CD expands from the inner end portion 72c to the outer end portion 72d.

[0043] The positioning groove 72 has a bottom portion 72a, and a pair of side portions 72b rising from the bottom portion 72a. The through hole 73 through which the shaft portion 19b of the countersunk screw 19 is inserted is communicated in the bottom portion 72a. The pair of side portions 72b (see Figure 5 ) are provided in opposition in the circumferential direction CD of the bottom plate 71, respectively extend in the radial direction RD, and are connected to the inner end portion 72c and the outer end portion 72d.

[0044] The side portion 72b (see Figure 3 ) of the present disclosure has a straight wall surface 72e rising substantially perpendicularly with respect to the bottom portion 72a, and an inclined surface 72f curved from the straight wall surface 72e and rising obliquely with respect to the straight wall surface 72e. The inclined surface 72f is connected to the surface of the wave foil portion 92 supporting the inner region 71y. The pair of inclined surfaces 72f are arranged in opposition to each other, and the pair of inclined surfaces 72f are inclined in a manner so as to be farther apart from each other the farther apart from the bottom portion 72a. For example, the pair of inclined surfaces 72f are inclined in a manner so as to expand the width of the circumferential direction CD of the bottom plate 71 the farther apart from the bottom portion 72a. ​

[0045] The fixing support portion 93 of the foil unit 9 is bent from the top foil portion 91 and the corrugated foil portion 92, and is formed into a generally trapezoidal shape in cross-section. For example, the fixing support portion 93 includes a base plate portion 93b and a pair of side plate portions 93c. The base plate portion 93b is opposite to the bottom 72a of the positioning groove 72. The pair of side plate portions 93c are bent from the base plate portion 93b and connected to the top foil portion 91 and the corrugated foil portion 92. The pair of side plate portions 93c are conical in shape in plan view, fitting into the positioning groove 72 (see reference). Figure 6 When the fixing bearing part 93 is fitted into the positioning groove 72, the outer surface portion that contacts the positioning groove 72 is the fitting protrusion 94, and the opposite, inner surface portion is the receiving recess 95.

[0046] The base plate portion 93b, viewed from above, has a conical shape consistent with the positioning groove 72, for example, it is a roughly isosceles triangle with two long sides and a short side of equal length. The apex of the base plate portion 93b is arranged along the inner end portion 72c of the positioning groove 72, and the short side portion is arranged along the outer end portion 72d of the positioning groove 72. A pair of side plate portions 93c are erected from the two long sides of the base plate portion 93b, and are inclined such that the distance between them increases as they move further away from the base plate portion 93b. The inclination angle of the side plate portions 93c is substantially the same as the inclination angle of the inclined surface 72f of the positioning groove 72. As a result, the outer side of the side plate portion 93c, i.e., a portion of the fitting protrusion 94, is inclined in a manner that it fits into the inclined surface 72f of the positioning groove 72. In addition, the base plate portion 93b of this disclosure is separated from the wall surface of the positioning groove 72.

[0047] The foil fixing part 10 is fitted into the receiving recess 95 of the fixing receiving part 93. The foil fixing part 10, when viewed from above, is approximately in the shape of an isosceles trapezoid, and includes: an inner end portion 10a provided along the inner end portion 72c of the positioning groove 72, an outer end portion 10b provided along the outer end portion 72d, and a pair of side portions 10c of equal length. When viewed from above, the pair of side portions 10c are conical, consistent with the pair of side plate portions 93c of the fixing receiving part 93, and are provided to abut against the pair of side plate portions 93c.

[0048] The foil fixing part 10 is shown in cross-section (see reference). Figure 3 For example, it is roughly in the shape of an isosceles trapezoid. Foil fixing part 10 (see reference) Figure 6 It includes: a lower surface portion 10d opposite to the base plate portion 93b of the fixed bearing portion 93, an upper surface portion 10e opposite to the lower surface portion 10d, and a pair of side portions 10c. The pair of side portions 10c are inclined such that their width increases as they move away from the lower surface portion 10d. The inclination angle of the side portions 10c is substantially the same as the inclination angle of the side plate portion 93c. As a result, the side portions 10c are inclined in a manner that fits into the side plate portion 93c.

[0049] likeFigure 3 As shown, when the fitting protrusion 94 is fitted into the positioning groove 72, a gap S is generated between the bottom 72a of the positioning groove 72 and the fitting protrusion 94. That is, the positioning groove 72 and the fitting protrusion 94 are formed with a size that allows for the generation of the gap S. As a result, when the fitting protrusion 94 is pressed by the foil fixing part 10, minor misalignments can be corrected, so that the fitting protrusion 94 is properly pressed against the side surface 10c of the positioning groove 72.

[0050] Furthermore, the gap S extends radially from the inner periphery 71b of the base plate 71 to the outer periphery 71a. This gap S forms a cooling flow path that allows air to pass through, thus enabling heat dissipation.

[0051] like Figure 2 as well as Figure 6 As shown, a bulge 72g is provided at the outer end 72d of the positioning groove 72. The bulge 72g is a groove communicating with the positioning groove 72. The bulge 72g is provided in a manner that it is separated from the fitting protrusion 94 in the circumferential direction CD, forming a gap region AR that is non-contact with the fitting protrusion 94. When it is necessary to remove the fitting protrusion 94, the fitting protrusion 94 can be easily removed by inserting a tool or the like into the gap region AR. Furthermore, by communicating this gap region AR with the gap S formed at the bottom 72a of the positioning groove 72, a cooling flow path that allows air to pass through is formed, thereby enabling heat dissipation. In addition, in this disclosure, the bulge 72g is communicating with the gap S.

[0052] Reference Figure 6 An example of the assembly method of the foil unit 9 relative to the base plate 71 will be described. Multiple foil units 9 are arranged in a ring on the inner region 71y of the base plate 71. Here, each of the multiple foil units 9 is temporarily placed by inserting a fixing support 93 into a positioning groove 72, thereby easily aligning the foil unit 9 in terms of direction, circumferential CD, and radial RD.

[0053] Next, the foil fixing part 10 is pressed into the receiving recess 95 of the foil unit 9, and the countersunk screw 19 is inserted from the back side 7b of the base plate 71 and screwed into the foil fixing part 10. By tightening the countersunk screw 19, the foil fixing part 10 is fitted into the receiving recess 95 in a way that opens the receiving recess 95 of the foil unit 9. As a result, the fitting protrusion 94 on the back side of the receiving recess 95 is pressed against the inclined surface 72f of the positioning groove 72 and properly fitted.

[0054] If the fastening of all the foil units 9 based on the flat head screws 19 and the foil fixing portion 10 is completed, the assembly of the foil units 9 with respect to the base plate 71 is completed. After the assembly of the foil units 9, the pair of the thrust air bearings 7 is disposed in the rotary machine 1 in a manner of being separated by the thrust ring 61. Here, the head portions 19a of the flat head screws 19 are respectively arranged on the back surfaces 7b of the pair of the thrust air bearings 7. The head portions 19a of the flat head screws 19 on the back surface 7b side of the first thrust air bearing 7 are arranged in a manner of being pressed by the motor housing 4 (refer to Figure 3 and Figure 7 (a) of FIG. 1). In addition, the head portions 19a of the flat head screws 19 on the back surface 7b of the second thrust air bearing 7 are arranged in a manner of being pressed by the compressor housing 31. As a result, loosening of the flat head screws 19, displacement of the foil units 9 from the base plate 71, and stable maintenance of the bearing function of the thrust air bearings 7 can be achieved.

[0055] Next, the function of supporting the rotary shaft 6 to be rotatable by the thrust air bearings 7 will be described with reference to Figure 7 (a) of FIG. 1. As shown in Figure 7 (a) of FIG. 1, the pair of the thrust air bearings 7 is arranged in a manner of sandwiching the thrust ring 61 fixed to the rotary shaft 6, thereby forming the shaft support structure 70. In a stationary state, i.e., a non-rotating state, the front end portions 91b of the top foil portions 91 of the foil units 9 are in contact with the thrust ring 61.

[0056] As shown in Figure 7 (b) of FIG. 1, when the rotary shaft 6 rotates, air pressure is applied to the top foil portions 91 from the root portions 91a side, thereby generating a wedge effect. By the wedge effect, the front end portions 91b of the top foil portions 91 are separated from the thrust ring 61 and are held. When the rotary shaft 6 attempts to displace in the direction of the axis L (thrust direction), the thrust ring 61 approaches the top foil portions 91 on one side. As a result, since the top foil portions 91 are cushioned by the undulating wave foil portions 92, displacement in the thrust direction of the rotary shaft 6 is suppressed.

[0057] The function and effect of the above-described thrust air bearings 7 will be described. The thrust air bearings 7 have a plurality of the foil units 9, and the top foil portions 91 of the foil units 9 are integrally provided with the wave foil portions 92. That is, by installing one foil unit 9, the top foil portions 91 and the wave foil portions 92 can be installed without displacement. Therefore, compared with the case where the wave foil and the top foil are separately installed, the installation of the wave foil portions 92 and the top foil portions 91 becomes easy. Moreover, by arranging the plurality of the foil units 9 in a row while arranging them in a predetermined position, the arrangement of all the top foil portions 91 and the wave foil portions 92 is completed.

[0058] Further, the foil unit 9 of the thrust air bearing 7 is detachable with respect to the bottom plate 71. As a result, in the case where the foil unit 9 has a failure, the failed foil unit 9 is removed from the bottom plate 71, and a new foil unit 9 can be easily replaced. For example, in a stationary state, the top foil portion 91 is in contact with the wave foil portion 92, and is separated when the rotating shaft 6 rotates. That is, the top foil portion 91 repeatedly performs contact and separation with respect to the wave foil portion 92, and thus plating or the like on the surface can be peeled off. In such a case, by the thrust air bearing 7, only the failed foil unit 9 can be replaced at the time of maintenance, and thus the efficiency is very high.

[0059] Further, the positioning groove 72 of the thrust air bearing 7 is provided so as to extend in the radial direction RD of the annular bottom plate 71. The fixed receiving portion 93 is provided with an engagement protrusion 94 that is engaged with the positioning groove 72. The foil unit 9 is positioned by the fixed receiving portion 93 that is housed in the positioning groove 72, and the positioning groove 72 is provided so as to extend in the radial direction RD. As a result, positional displacement in a direction that intersects the radial direction RD, for example, the circumferential direction CD, can be suppressed.

[0060] Further, the fixed receiving portion 93 of the foil unit 9 is provided with an engagement protrusion 94 that is engaged with the tapered positioning groove 72 in the radial direction RD. The engagement protrusion 94 is formed in a tapered shape that is engaged with the positioning groove 72. Thus, when the engagement protrusion 94 is crimped to the positioning groove 72 by the foil fixing portion 10, positional correction is performed at an appropriate position by the cooperation of the tapered shape of the engagement protrusion 94 and the tapered shape of the positioning groove 72, and positional displacement in the radial direction RD can be suppressed.

[0061] Further, the inclined surfaces 72f of the positioning groove 72 are respectively provided at a pair of side portions 72b that are opposed in the circumferential direction CD. The engagement protrusion 94 is inclined so as to be engaged with the pair of inclined surfaces 72f. Thus, when the engagement protrusion 94 is crimped to the positioning groove 72 by the foil fixing portion 10, positional correction is performed at an appropriate position by the cooperation of the inclination of the engagement protrusion 94 and the inclined surfaces 72f of the positioning groove 72, and positional displacement in the circumferential direction CD can be suppressed.

[0062] Further, a gap S is present between the bottom portion 72a of the positioning groove 72 and the engagement protrusion 94, and the gap S extends in the radial direction RD. By the gap S, a cooling flow path through which air passes can be formed, and as a result, a heat dissipation function can be exerted.

[0063] Further, a bulging portion 72g that forms a gap region AR is provided at the outer end portion 72d of the positioning groove 72, and in the case where the engagement protrusion 94 needs to be pulled out, the engagement protrusion 94 can be easily pulled out using the gap region AR.

[0064] Next, the operation of the present embodiment will be described with reference to the flowchart of FIG. 8. Figure 8A thrust air bearing 7 of another embodiment of the present disclosure will be described. The thrust air bearing 7 of the other embodiment has a configuration, elements, functions, and effects in common with the above-described thrust air bearing 7 of the embodiment. Specifically, only the configuration of the positioning groove 72A of the bottom plate 71A is different from the above-described thrust air bearing 7. Therefore, the common configuration, elements, functions, and effects will be described with the same reference numerals and detailed description will be omitted. Figure 8 The bottom plate 71A of the thrust air bearing 7 of the other embodiment will be mainly described, and the common configuration, elements, functions, and effects will be described with the same reference numerals and detailed description will be omitted.

[0065] The bottom plate 71A has an outer periphery 71a and an inner periphery 71b on the opposite side of the outer periphery 71a in the radial direction RD. The outer end portion 72d of the positioning groove 72A reaches the outer periphery 71a of the bottom plate 71A and is open, thereby forming an insertion port 72j. The fitting protrusion 94 of the foil unit 9 can be inserted from the insertion port 72j.

[0066] According to the other embodiment, since the fitting protrusion 94 of the foil unit 9 can be inserted from the side that does not interfere with the other foil units 9 and installed in the insertion port 72j, the assembly of the thrust air bearing 7 becomes easy.

[0067] The present disclosure is not limited to the above-described embodiments. For example, in the above-described embodiment, as one example of a rotating machine, the thrust air bearing provided to the turbocharger of the electrically assisted type was described, but the thrust air bearing can be widely applied to a thrust air bearing that rotatably supports a rotating shaft.

[0068] Explanation of Reference Numerals

[0069] 6...rotating shaft; 7...thrust air bearing; 71...bottom plate; 71A...bottom plate; 72j...insertion port; 71a...outer periphery; 71b...inner periphery; 72...positioning groove; 72A...positioning groove; 72a...bottom portion; 72c...inner end portion; 72d...outer end portion; 72f...inclined surface; 72g...bulge portion; 9...foil unit; 91...top foil portion; 92...wave foil portion; 93...fixed receiving portion; 94...fitting protrusion; 95...receiving recess; 10...foil fixing portion; AR...gap region; RD...radial direction; CD...circumferential direction; S...gap.

Claims

1. A thrust air bearing that is a thrust air bearing that supports a rotating shaft, characterized by comprising: a plurality of foil units arranged in a ring shape; a ring-shaped base plate that has the plurality of foil units fixed thereto; and a foil fixing portion that fixes the foil units to the base plate.

2. The thrust air bearing according to claim 1, characterized in that the foil fixing portion has a lower surface portion that opposes a base plate portion of the fixed receiving portion, an upper surface portion on the opposite side from the lower surface portion, and a pair of side surface portions that are inclined in a manner such that the width of the circumferential direction increases the farther away from the lower surface portion.

3. The thrust air bearing according to claim 1 or 2, characterized in that a positioning groove that houses the fixed receiving portion is provided in the base plate, the positioning groove is provided so as to extend in the radial direction of the ring-shaped base plate, and the fixed receiving portion has a fitting protrusion that fits into the positioning groove, and a receiving recess on the opposite side from the fitting protrusion into which the foil fixing portion fits.

4. The thrust air bearing according to claim 3, characterized in that the base plate has an outer peripheral edge, and an inner peripheral edge on the opposite side from the outer peripheral edge in the radial direction, the positioning groove is formed in a tapered shape in which the width of the circumferential direction of the base plate increases from an inner end portion that is close to the inner peripheral edge to an outer end portion that is close to the outer peripheral edge, and the fitting protrusion is formed in a tapered shape that fits into the positioning groove, and is crimped to the positioning groove by the foil fixing portion.

5. The thrust air bearing according to claim 4, characterized in that the positioning groove has a bottom portion, and a pair of side portions that stand up from the bottom portion and are opposed in the circumferential direction, the pair of side portions have a pair of inclined surfaces that are inclined in a manner such that the width of the circumferential direction increases the farther away from the bottom portion, and the fitting protrusion is inclined in a manner that fits into the pair of inclined surfaces, and is crimped to the inclined surfaces by the foil fixing portion.

6. The thrust air bearing according to claim 3, characterized in that the positioning groove has a bottom portion, and a gap is provided between the bottom portion and the fitting protrusion, the gap extending in the radial direction.

7. The thrust air bearing according to claim 3, characterized in that a bulge portion is provided in the positioning groove, the bulge portion being separated from the fitting protrusion in the circumferential direction so as to form a gap region.

8. The thrust air bearing according to claim 3, characterized in that the base plate has an outer peripheral edge, and an inner peripheral edge on the opposite side from the outer peripheral edge in the radial direction, and the positioning groove has an insertion opening that is open at the outer peripheral edge, and the fitting protrusion is capable of being inserted from the insertion opening.

9. A thrust air bearing that is a thrust air bearing that supports a rotating shaft, characterized by ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Possessing: a plurality of foil units arranged in a ring shape; a ring-shaped base plate on which the plurality of foil units are fixed; and a foil fixing portion that fixes the foil units to the base plate, the foil unit possesses: a top foil portion; and a wave foil portion that is provided integrally with the top foil portion and is arranged on the opposite side of the top foil portion in the circumferential direction in which the ring shape is formed; and a fixing receiving portion that is provided between the top foil portion and the wave foil portion and is mounted to the base plate by the foil fixing portion, the foil units are arranged in a manner in which the top foil portions overlap the wave foil portions of the other foil units adjacent thereto, a positioning groove that accommodates the fixing receiving portion is provided in the base plate, the positioning groove is provided so as to extend in the radial direction of the ring-shaped base plate, the fixing receiving portion possesses a fitting protrusion that fits into the positioning groove and a receiving recess on the opposite side of the fitting protrusion for fitting of the foil fixing portion, the base plate possesses an outer peripheral edge and an inner peripheral edge on the opposite side of the outer peripheral edge in the radial direction, the positioning groove is formed in a tapered shape in which the width in the circumferential direction of the base plate expands from an inner end portion close to the inner peripheral edge to an outer end portion close to the outer peripheral edge, the fitting protrusion is formed in a tapered shape that fits into the positioning groove and is crimped to the positioning groove by the foil fixing portion.

10. A thrust air bearing that is a thrust air bearing that supports a rotating shaft, characterized by Possessing: a plurality of foil units arranged in a ring shape; a ring-shaped base plate on which the plurality of foil units are fixed; and a foil fixing portion that fixes the foil units to the base plate, the foil unit possesses: a top foil portion; and a wave foil portion that is provided integrally with the top foil portion and is arranged on the opposite side of the top foil portion in the circumferential direction in which the ring shape is formed; and a fixing receiving portion that is provided between the top foil portion and the wave foil portion and is mounted to the base plate by the foil fixing portion, the foil units are arranged in a manner in which the top foil portions overlap the wave foil portions of the other foil units adjacent thereto, a positioning groove that accommodates the fixing receiving portion is provided in the base plate, the positioning groove is provided so as to extend in the radial direction of the ring-shaped base plate, the fixing receiving portion possesses a fitting protrusion that fits into the positioning groove and a receiving recess on the opposite side of the fitting protrusion for fitting of the foil fixing portion, the positioning groove possesses a bottom portion and a pair of side portions that stand from the bottom portion and are opposed in the circumferential direction, the pair of side portions possess a pair of inclined surfaces that are inclined in a manner in which the width in the circumferential direction expands the farther they are from the bottom portion, the fitting protrusion is inclined in a manner that fits into the pair of inclined surfaces and is crimped to the inclined surfaces by the foil fixing portion.

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