Fluid machine in which deformation of a buffer film in a film bearing is limited.

Abstract

Fluid machine (10) comprising: a rotary shaft (40); an actuating element (51, 52) configured to discharge fluid by rotation of the rotary shaft (40); a housing (11) accommodating the rotary shaft (40) and the actuating element (51, 52); and a foil bearing (20, 22) arranged in the housing (11) and rotatably supporting the rotary shaft (40), the foil bearing (20, 22) comprising: a bearing housing (71) with a cylindrical shape; a cover foil (72) arranged between an inner circumferential surface of the bearing housing (71) and the rotary shaft (40);and a buffer film (73) arranged between the inner circumferential surface of the bearing housing (71) and the cover film (72) and elastically supporting the cover film (72), characterized in that the bearing housing (71) has a projection (74a, 81) which extends inwards in a radial direction of the bearing housing (71) from the inner circumferential surface of the bearing housing (71), and the projection (74a, 81) has a stop surface (74d) which is configured to limit deformation of the buffer film (73) to an elastic range, so that it does not reach a plastic range by abutting an outer surface of the cover film (72) when the cover film (72) is displaced outwards in the radial direction of the bearing housing (71).

Description

BACKGROUND The present disclosure relates to a fluid machine. For example, JP 2015 - 183 568 A discloses a fluid machine with a foil bearing that rotatably supports a rotating shaft of the fluid machine. The foil bearing comprises a bearing housing, a cover foil, and a buffer foil. Furthermore, from JP S61-36726 U, an axial bearing is known comprising a bearing housing, a cover film, a buffer film, and a projection. The projection is arranged between the bearing housing and the buffer film and can abut the buffer film. Furthermore, DE 10 2014 226 840 A1 discloses a foil bearing for supporting a shaft, comprising a bearing housing, a bottom foil, a buffer foil, and a top foil arranged radially inside one another in that order, with the bearing housing positioned radially at the outermost point. Projections are also provided on the bearing housing for more precise positioning of the shaft. The fluid machine comprises a rotary shaft, an actuating element configured to deliver fluid upon rotation of the rotary shaft, and a housing that accommodates the rotary shaft and the actuating element. A foil bearing / foil slide bearing arranged within the housing and rotatably supporting the rotary shaft is disclosed, for example, in WO 2013 / 024674. The foil bearing comprises a cylindrical bearing housing, a cylindrical cover foil, and a cylindrical buffer foil / elastic foil / corrugated surface. The cover foil is positioned between an inner circumferential surface of the bearing housing and the rotary shaft, rotatably supporting the shaft without contacting it as the shaft rotates. The buffer foil is positioned between the inner circumferential surface of the bearing housing and the cover foil, providing elastic support for the cover foil. However, if the buffer film in such a fluid machine is compressed, for example by vibrations of the rotating shaft, to such an extent that it deforms beyond the elastic range and into the plastic range, the buffer film deforms plastically, potentially preventing the film bearing from rotating freely and thus rendering the rotating shaft inoperable. If the film bearing no longer allows the rotating shaft to rotate freely, the reliability of the fluid machine deteriorates. The present disclosure was made in view of the above circumstances and aims to provide a fluid machine that exhibits improved reliability. SUMMARY A fluid machine comprises a rotating shaft, an actuator configured to deliver fluid upon rotation of the shaft, a housing that accommodates the rotating shaft and actuator, and a foil bearing / foil slide bearing located within the housing that rotatably supports the rotating shaft. The foil bearing has a cylindrical bearing housing, a cover foil positioned between an inner circumferential surface of the bearing housing and the rotating shaft, and a buffer foil / elastic foil / sliding foil positioned between the inner circumferential surface of the bearing housing and the cover foil, providing elastic support for the cover foil. The bearing housing has a projection extending inward in a radial direction from the inner circumferential surface of the bearing housing.The projection has a stop surface configured to limit the deformation of the buffer film to an elastic range, so that it does not reach a plastic range by abutting an outer surface of the cover film when the cover film is displaced / shifted outwards in the radial direction of the bearing housing. Further aspects and benefits of the revelation will become apparent from the following description in conjunction with the accompanying drawings, which exemplify the principles of the revelation. BRIEF DESCRIPTION OF THE DRAWINGS The disclosure, its subject matter and advantages, are best understood by reference to the following description of the embodiments in conjunction with the accompanying drawings, in which: Fig. 1 is a side sectional view of a fluid machine according to an embodiment of the present disclosure; Fig. 2 is a perspective exploded view of a first foil bearing and a retaining element; Fig. 3 is a longitudinal sectional view of the first foil bearing and a rotating shaft; Fig. 4 is a longitudinal sectional view of the first foil bearing, the retaining element, and the rotating shaft; Fig. 5 is a detailed sectional view of a retaining groove and surrounding parts; Fig. 6 is a detailed sectional view of a rotating stop and the parts surrounding it; Fig. 7 is a detailed sectional view of the first foil bearing and the surrounding parts; Fig. 8 is a detailed sectional view of a second foil bearing and the surrounding parts; Fig.Figure 9 is a sectional view of projections according to another embodiment of the present disclosure; and Figure 10 is a sectional view of projections according to the prior art. DETAILED DESCRIPTION OF THE EXECUTION FORMS An embodiment of a fluid machine according to the present disclosure is described in the following sections with reference to Figures 1, 2, 3, 4, 5, 6, 7 to 8. A centrifugal compressor is mounted on a fuel cell vehicle. The centrifugal compressor corresponds to the fluid machine of the present embodiment. A fuel cell system for supplying the fuel cells with oxygen and hydrogen for power generation is mounted on the fuel cell vehicle. The centrifugal compressor then compresses the air containing the oxygen supplied to the fuel cells. The air corresponds to a fluid. As shown in Fig. 1, a centrifugal compressor 10 has a housing 11 which has a cylindrical shape. The housing 11 comprises a motor housing 12, a first compressor housing 13, a second compressor housing 14, a partition 15, a first intermediate housing 16, and a second intermediate housing 17. The motor housing 12, the first compressor housing 13, the second compressor housing 14, the partition 15, the first intermediate housing 16, and the second intermediate housing 17 are each made of metal, e.g., aluminum. The engine housing 12 has a cylindrical shape with a base and features a front wall 12a with a plate-like shape and a circumferential wall 12b that extends cylindrically from an outer circumference of the front wall 12a. The second intermediate housing 17 is connected to the engine housing 12 in such a way that an opening of the second intermediate housing 17 on the side of the circumferential wall 12b opposite the front wall 12a is closed. The front wall 12a and the circumferential wall 12b of the engine housing 12, together with the second intermediate housing 17, define an engine chamber 18. An inlet / intake hole 12h for drawing in air is formed in the circumferential wall 12b at a location / position near the front wall 12a. The inlet hole 12h communicates with the engine chamber 18. Therefore, air is drawn into the engine chamber 18 through the inlet hole 12h. The second intermediate housing 17 has a shaft entry hole 17a in a central / middle region of the second intermediate housing 17. The shaft entry hole 17a is circular. The second intermediate housing 17 has a first bearing retaining section 19, which is cylindrical in shape. The first bearing retaining section 19 is formed in the middle region of the second intermediate housing 17. An inner surface of the first bearing retaining section 19 is in contact with the shaft entry hole 17a. A central axis of the first bearing retaining section 19 coincides with a central axis of the shaft entry hole 17a. The first bearing retaining section 19 holds a first foil bearing 20, which corresponds to a foil bearing. The end wall 12a of the motor housing 12 has a second bearing support section 21, which has a cylindrical shape. The second bearing support section 21 is formed in a central region of the end wall 12a of the motor housing 12. The central axis of the first bearing support section 19 coincides with a central axis of the second bearing support section 21. The second bearing support section 21 holds a second foil bearing 22, which corresponds to the first foil bearing. Thus, the first foil bearing 20 and the second foil bearing 22 are arranged inside the housing 11. The foil bearing according to the embodiment comprises the first foil bearing 20 and the second foil bearing 22. The second intermediate housing 17 has a first chamber-forming recess 17b, which is formed in an outer surface of the second intermediate housing 17 on a side opposite the motor chamber 18. The first chamber-forming recess 17b is connected to the shaft entry hole 17a. The second intermediate housing 17 also has a plurality of connecting holes 23. The connecting holes 23 are located at positions near an outer circumference of the second intermediate housing 17. The connecting holes 23 extend through the second intermediate housing 17. The connecting holes 23 establish a connection between the motor chamber 18 and the first chamber-forming recess 17b. The first intermediate housing 16 is connected to the second intermediate housing 17 such that it closes an opening of the first chamber-forming recess 17b. The first intermediate housing 16 and the first chamber-forming recess 17b of the second intermediate housing 17 define a thrust bearing receiving chamber / thrust bearing receiving chamber 25. The first intermediate housing 16 has a shaft entry hole 16a in a central area of ​​the first intermediate housing 16. The shaft entry hole 16a is a circular hole. The first intermediate housing 16 has a plurality of connecting holes 16b. The connecting holes 16b are located near an outer circumference of the first intermediate housing 16. The connecting holes 16b extend through the first intermediate housing 16. The first intermediate housing 16 has a second chamber-forming recess 16c, which is formed in an outer surface of the first intermediate housing 16 on a side opposite the thrust bearing receiving chamber 25. The second chamber-forming recess 16c is connected to the shaft entry hole 16a. The connecting holes 16b establish a connection between the thrust bearing receiving chamber 25 and the second chamber-forming recess 16c. The first compressor housing 13 is cylindrical and has a first inlet 24 for drawing in air. The first inlet 24 is a circular hole. The first compressor housing 13 is connected to the first intermediate housing 16 in such a way that a central axis of the first inlet 24 coincides with a central axis of the shaft entry hole 16a. The first inlet 24 is connected to the second chamber-forming recess 16c. The partition 15 is connected to an end face of the first compressor housing 13 on a side opposite the first intermediate housing 16. The partition 15 is panel-shaped. The partition 15 has a circular through-hole 27 in a central region. The through-hole 27 extends through the partition 15 in a direction consistent with its thickness. The partition 15 is connected to the first compressor housing 13 in such a way that the central axis of the through-hole 27 coincides with the central axis of the first inlet 24. The first inlet 24 faces the partition 15 in the direction in which its central axis extends. Between the partition 15 and the first compressor housing 13, a first impeller chamber 28, a first outlet chamber 29, and a first diffuser flow channel 30 are formed. The first impeller chamber 28 corresponds to an impeller chamber and is connected to the first inlet 24. The first outlet chamber 29 extends around the central axis of the first inlet 24 on a circumference of the first impeller chamber 28. The first diffuser flow channel 30 establishes a connection between the first impeller chamber 28 and the first outlet chamber 29. The second compressor housing 14 is cylindrical and has a second inlet 32 ​​for drawing in air. The second inlet 32 ​​is a circular opening. The second compressor housing 14 is connected to an end face of the partition 15 on a side opposite the first compressor housing 13 in such a way that the central axis of the second inlet 32 ​​coincides with the central axis of the first inlet 24. The second inlet 32 ​​faces the partition 15 in the direction in which the central axis of the second inlet 32 ​​extends. Between the partition 15 and the second compressor housing 14, a second impeller chamber 33, a second outlet chamber 34, and a second diffuser flow channel 35 are formed. The second impeller chamber 33 corresponds to the first impeller chamber and is connected to the second inlet 32. The second outlet chamber 34 extends around the central axis of the second inlet 32 ​​on one circumference of the second impeller chamber 33. The second diffuser flow channel 35 connects the second impeller chamber 33 and the second outlet chamber 34. Therefore, the housing 11 comprises the first impeller chamber 28 and the second impeller chamber 33. The partition 15 separates the first impeller chamber 28 and the second impeller chamber 33. The first outlet chamber 29 is connected to the second inlet 32 ​​by a passage (not shown). The centrifugal compressor 10 has a rotating shaft 40 and an electric motor 41 that rotates the rotating shaft 40. The electric motor 41 is housed in the motor chamber 18. The rotating shaft 40 extends axially through the housing 11, passing through an inner surface of the second bearing section 21, the motor chamber 18, an inner surface of the first bearing section 19, the shaft entry hole 17a, the thrust bearing chamber 25, the shaft entry hole 16a, the first inlet 24, the first impeller chamber 28, the through-hole 27, the second impeller chamber 33, and the second inlet 32, in that order. Therefore, the rotating shaft 40 is positioned above the first impeller chamber 28 and the second impeller chamber 33 and is inserted through the through-hole 27.An axis L of the rotary shaft 40 coincides with the central axes of the first bearing support section 19, the second bearing support section 21, the shaft entry hole 17a, the shaft entry hole 16a, the first inlet 24, the through hole 27, and the second inlet 32. The rotary shaft 40 is thus housed / received in the casing 11. In the following description, the axial direction of the rotary shaft 40, in which the axis L of the rotary shaft 40 extends, can be referred to as the thrust direction, and the radial direction of the rotary shaft 40 can be referred to as the radial direction. The electric motor 41 comprises a stator 42 and a rotor 43. The stator 42 has a cylindrical core 44 and a coil 45 wound around the core 44. The core 44 is attached to an inner circumferential surface of the circumferential wall 12b of the motor housing 12. The rotor 43 is located within the core 44 in the motor chamber 18. The rotor 43 rotates integrally with the shaft 40. The rotor 43 has a core 43a attached to the shaft 40 and a plurality of permanent magnets (not shown) provided on the core 43a. The rotor 43 rotates by current supplied to the coil 45 under the control of an inverter (not shown), and the shaft 40 rotates integrally with the rotor 43. The centrifugal compressor 10 has a first impeller 51 and a second impeller 52, which correspond to actuating elements. The first impeller 51 and the second impeller 52 are made of aluminum, for example. The stiffness of the aluminum material from which the first impeller 51 and the second impeller 52 are formed is lower than the stiffness of the aluminum material from which the partition 15 is formed. The first impeller 51 and the second impeller 52 are connected to a first end section of the rotating shaft 40. The second impeller 52 is arranged closer to the first end section of the rotating shaft 40 than the first impeller 51. The first foil bearing 20 and the second foil bearing 22 are arranged closer to a second end section of the rotating shaft 40 than the first impeller 51 and the second impeller 52. The first impeller 51 is housed / mounted in the first impeller chamber 28. The first impeller 51 has a conical trapezoidal shape. The first impeller 51 is connected to the first end section of the rotating shaft 40. The second impeller 52 is housed / mounted in the second impeller chamber 33. The second impeller 52 has the shape of a conical trapezoid. The second impeller 52 is connected to the first end section of the rotating shaft 40. The rotating shaft 40, the first impeller 51, and the second impeller 52 are thus housed / mounted in the casing 11. The first foil bearing 20 and the second foil bearing 22 support / bearing the rotary shaft 40 so that it can rotate freely. The first foil bearing 20 and the second foil bearing 22 keep the rotary shaft 40 in rotatable contact with the rotary shaft 40 until the number of revolutions of the rotary shaft 40 reaches the number of sliding revolutions at which the rotary shaft 40 slides off the first foil bearing 20 and the second foil bearing 22 by actuation of the first foil bearing 20 and the second foil bearing 22. When the number of revolutions of the rotating shaft 40 reaches the number of sliding revolutions, the rotating shaft 40 slides away from the first foil bearing 20 and the second foil bearing 22 due to dynamic pressures generated between the rotating shaft 40 and the first foil bearing 20 and between the rotating shaft 40 and the second foil bearing 22, so that the first foil bearing 20 and the second foil bearing 22 rotatably support / support the rotating shaft 40 without contact with the rotating shaft 40.Thus, the first foil bearing 20 and the second foil bearing 22 are aerodynamic bearings that allow the rotating shaft 40 to rotate in the radial direction. A specific configuration of the first film support 20 of the present embodiment is described below. Since the configuration of the second film support 22 is identical to that of the first film support 20, a detailed description of the configuration of the second film support 22 is omitted. As shown in Figs. 2 and 3, the first foil bearing 20 comprises a bearing housing 71, a cover foil 72, and a buffer foil / elastic foil / corrugated foil 73. The bearing housing 71 has a cylindrical shape. The bearing housing 71 has a retaining groove 71a in an inner circumferential surface of the bearing housing 71. The retaining groove 71a extends in an axial direction of the bearing housing 71. The retaining groove 71a has a pair of side surfaces 71b that extend in the axial direction of the bearing housing 71. The pair of side surfaces 71b is continuous with the inner circumferential surface of the bearing housing 71. The pair of side surfaces 71b extends parallel to each other. The retaining element 71a has an outer surface 71c that extends in the axial direction of the bearing housing 71. The outer surface 71c connects the two edges of the pair of side surfaces 71b on a side opposite the inner circumferential surface of the bearing housing 71. One end of the retaining groove 71a is open axially to an end face of the bearing housing 71. Therefore, the pair of side faces 71b and the outer surface 71c are continuous with one end face of the bearing housing 71. The other end of the retaining groove 71a is not open axially to the other end face of the bearing housing 71, but is closed. Therefore, the other end of the retaining groove 71a extends radially along the bearing housing 71, forming a stepped surface 71e that is continuous with the inner circumferential surface of the bearing housing 71. The pair of side faces 71b and the outer surface 71c are connected to the stepped surface 71e. The cover sheet 72 has a substantially cylindrical shape. The cover sheet 72 is formed into this cylindrical shape, for example, by bending a flexible, strip-shaped metal plate made of stainless steel or the like, with one longer side extending in a circumferential direction and one shorter side extending in an axial direction. One end section of the cover sheet 72 in the circumferential direction, i.e., a fixed end section 72a, is bent outwards in a radial direction. The other end section of the cover sheet 72 in the circumferential direction, i.e., a free end section 72b, faces away from a base end section of the fixed end section 72a in the circumferential direction. Therefore, the cover sheet 72 has an incomplete ring shape, with a portion of it cut out. The cover sheet 72 is arranged inside the bearing housing 71, with the fixed end section 72a inserted into the retaining groove 71a. Therefore, a portion of the cover sheet 72 is inserted into the retaining groove 71a. The cover sheet 72 is arranged inside the bearing housing 71, with the fixed end section 72a being held in the retaining groove 71a by being inserted into the retaining groove 71a. A portion of the fixed end section 72a overlaps the stepped surface 71e in the axial direction of the bearing housing 71. The cover sheet 72 is arranged radially outside the rotating shaft 40. The cover sheet 72 rotatably supports the rotating shaft 40 without contacting it while the rotating shaft 40 rotates. The buffer film 73 has a substantially cylindrical shape. The buffer film 73 is formed into this cylindrical shape, for example, by bending a flexible, strip-shaped metal plate made of stainless steel or the like, with one longer side extending circumferentially and one shorter side extending axially. The thickness of the cover film 72 is substantially equal to that of the buffer film 73. One end section of the buffer film 73 in the circumferential direction, i.e., a fixed end section 73a, is bent outwards in a radial direction. The other end section of the buffer film 73 in the circumferential direction, i.e., a free end section 73b, faces away from a base end section of the fixed end section 73a in the circumferential direction.Therefore, the buffer film 73 has the fixed end section 73a and the free end section 73b and has an incomplete ring shape, with one part of it cut out. The buffer film 73 is arranged inside the bearing housing 71, with the fixed end section 73a inserted into the retaining groove 71a. Therefore, a portion of the buffer film 73 is inserted into the retaining groove 71a. The buffer film 73 is arranged inside the bearing housing 71, with the fixed end section 73a being held in the retaining groove 71a by being inserted into the retaining groove 71a. A portion of the fixed end section 73a overlaps with the stepped surface 71e in the axial direction of the bearing housing 71. The buffer film 73 is arranged between the inner circumferential surface of the bearing housing 71 and the cover film 72. Therefore, the buffer film 73 is arranged outside the cover film 72 in the radial direction. The buffer film 73 then elastically supports the cover film 72.The buffer film 73 has a plurality of bottom sections 73c that are in contact with the inner circumferential surface of the bearing housing 71. The bottom sections 73c extend along the inner circumferential surface of the bearing housing 71. The buffer film 73 also comprises a plurality of raised sections 73f that are in contact with an outer circumferential surface of the cover film 72, corresponding to an outer surface of the cover film 72. Each of the raised sections 73f projects in a direction away from the inner circumferential surface of the bearing housing 71 and is also arcuately curved so that it rises towards the outer circumferential surface of the cover film 72. The buffer film 73 has a corrugated shape in which the bottom sections 73c and the raised sections 73f are arranged alternately in the circumferential direction of the buffer film 73. The circumferential direction of the buffer film 73 coincides with the circumferential direction of the bearing housing 71.Therefore, the buffer film 73 has a configuration in which the bottom sections 73c and the raised sections 73f are arranged alternately from the fixed end section 73a of the buffer film 73 to the free end section 73b of the buffer film 73 in the circumferential direction of the bearing housing 71. The axial length of the cover film 72 is shorter than the axial length of the bearing housing 71. The axial length of the buffer film 73 is also shorter than the axial length of the cover film 72. An end section of the cover film 72 on one side of the same projectes axially from an end section of the buffer film 73 on the same side. This end section of the cover film 72 on one side extends further axially into the bearing housing 71 than the end section of the buffer film 73 on the same side, thus forming a non-overlap section 72d. The non-overlap section 72d is not overlapped by the buffer film 73 in the radial direction of the bearing housing 71. The cover sheet 72 has a cutout 72c at an end edge of the fixed end section 72a of the cover sheet 72 on one side of the cover sheet 72 in the axial direction. The cutout 72c has a first edge 721c extending from the end edge of the fixed end section 72a of the cover sheet 72 on one side of the cover sheet 72 in the axial direction of the cover sheet 72, and a second edge 722c that is continuous with the first edge 721c and extends outwards from the first edge 721c in the radial direction of the cover sheet 72. An edge of the second edge 722c on a side opposite the first edge 721c continues with an end edge of the fixed end section 72a of the cover sheet 72 on the radially outer side of the cover sheet 72. The length from the second edge 722c to the end edge of the fixed end section 72a of the cover film 72 on the other side of the cover film 72 in the axial direction is identical to the length of the buffer film 73 in the axial direction. The length of the fixed end section 72a of the cover film 72 from the second edge 722c to the end edge of the fixed end section 72a of the cover film 72 on the other side of the cover film 72 in the axial direction is identical to the length of the fixed end section 73a of the buffer film 73 in the axial direction of the buffer film 73. When the rotating shaft 40 is not rotating, the bottom sections 73c of the buffer film 73 are in contact with the inner circumferential surface of the bearing housing 71, and the raised sections 73f of the buffer film 73 are in contact with the outer circumferential surface of the cover film 72. When the rotating shaft 40 is rotating, the cover film 72 deforms elastically outwards in the radial direction, allowing air to enter a space between the rotating shaft 40 and the cover film 72, forming an air layer that generates dynamic pressure / stagnation pressure. Thus, the rotating shaft 40 is rotatably mounted through the cover film 72 via the air layer without touching the cover film 72. When the cover film 72 deforms elastically outwards in the radial direction due to the air layer formed between the rotating shaft 40 and the cover film 72, the raised sections 73f of the buffer film 73, which are in contact with the outer circumferential surface of the cover film 72, are pressed / pressed by the cover film 72, so that the buffer film 73 together with the cover film 72 deforms elastically outwards in the radial direction accordingly. In this way, the buffer film 73 elastically supports the cover film 72. The raised sections 73f are elastically deformed with the outward displacement of the cover film 72 in the radial direction of the bearing housing 71. As shown in Fig. 2 and Fig. 4, the centrifugal compressor 10 has a retaining element 74. The retaining element 74 has a main body 74a, a fixed section 74b, and a rotation stop 74c. The main body 74a has an annular shape. The outer diameter of the main body 74a is slightly smaller than the inner diameter of the bearing housing 71. The inner diameter of the main body 74a is larger than the outer diameter of the cover film 72. The thickness of the main body 74a is greater than that of the cover film 72 and the buffer film 73. As shown in Fig. 5, the fixed section 74b projects outwards from an outer circumferential surface of the main body 74a. The fixed section 74b is arranged in the retaining groove 71a. The fixed section 74b has a pair of contact surfaces 741b on both sides of the fixed section 74b in a circumferential direction of the main body 74a. The contact surfaces 741b extend along the respective side surfaces 71b of the retaining groove 71a. The fixed section 74b is pressed into the retaining groove 71a and fixed therein in a state in which the contact surfaces 741b are in contact with the respective side surfaces 71b of the retaining groove 71a. The retaining element 74 is arranged inside the bearing housing 71, with the fixed section 74b being pressed into and secured in the retaining groove 71a. In a state where the retaining element 74 is arranged within the bearing housing 71, as shown in Figs. 2 and 4, the outer circumferential surface of the main body 74a is in contact with the inner circumferential surface of the bearing housing 71 at one end of an opening of the bearing housing 71 on one side of the bearing housing 71 in the axial direction. The main body 74a is arranged at the opening of the bearing housing 71 on one side of the bearing housing 71 in the axial direction. Parts of the main body 74a are arranged at positions corresponding to all the respective raised sections 73f in the inner circumferential surface of the bearing housing 71, when viewed in the axial direction of the bearing housing 71. The main body 74a is therefore a projection that extends inwards from the inner circumferential surface of the bearing housing 71 in the radial direction of the bearing housing 71. The projection has a ring shape and extends over the entire circumference of the inner circumferential surface of the bearing housing 71.One of the parts of the main body 74a is arranged at a position corresponding to one of the raised sections 73f, which is located on one side near the free end section 73b of the buffer film 73 in the inner circumferential surface of the bearing housing 71, when viewed in the axial direction of the bearing housing 71. An inner circumferential surface of the main body 74a serves as a stop surface 74d, which is designed to limit deformation of the buffer film 73 to the elastic range, preventing it from entering the plastic range, by bearing against the outer circumferential surface of the cover film 72 when the cover film 72 is displaced radially outwards in the bearing housing 71. Therefore, the main body 74a has the stop surface 74d. The stop surface 74d is arcuate, extending along a contour of the cover film 72 when the cover film 72 is displaced. As shown in Fig. 5, part of the main body 74a is located on the radially outer side of the cover film 72 with respect to the first edge 721c of the cutout 72c. Most sections of the main body 74a are located on the radially outer side of the cover film 72 with respect to the end section of the outer circumferential surface of the cover film 72 on one side of the cover film 72 in the axial direction. One section of the main body 74a intersects / overlaps with the second edge 722c of the cutout 72c and with the fixed end section 73a of the buffer film 73 in the axial direction of the bearing housing 71, when viewed in the axial direction of the bearing housing 71. Therefore, one section of the main body 74a overlaps the part of the cover film 72 and the part of the buffer film 73 in the axial direction of the bearing housing 71. The main body 74a is arranged axially adjacent to / next to the buffer film 73.The main body 74a is arranged between an outer circumferential surface of the non-overlapping section 72d of the cover film 72 and the inner circumferential surface of the bearing housing 71. The outer circumferential surface of the non-overlapping section 72d of the cover film 72 corresponds to an outer surface of the non-overlapping section 72d. As shown in Fig. 2, the rotary stop 74c has the shape of an elongated quadrilateral prism extending from the fixed section 74b in the axial direction of the retaining element 74. Therefore, the rotary stop 74c is formed integrally with the main body 74a over the fixed section 74b. The rotary stop 74c has a pair of sandwich surfaces 741c on both sides of the rotary stop 74c in a circumferential direction of the main body 74a. The width between the pair of sandwich surfaces 741c is smaller than the width between the pair of contact surfaces 741b. One of the two sandwich surfaces 741c and one of the two contact surfaces 741b are flush with each other.As shown in Fig. 6, the sandwich surfaces 741c extend along the respective side surfaces 71b of the retaining groove 71a. The rotation stop 74c is inserted into the retaining groove 71a such that one of the two sandwich surfaces 741c is in contact with one of the two side surfaces 71b of the retaining groove 71a and the other of the two sandwich surfaces 741c is in contact with the fixed end section 72a of the cover film 72. The rotation stop 74c, inserted into the retaining groove 71a, is positioned between the fixed end section 72a of the cover film 72 and the fixed end section 73a of the buffer film 73, together with the other of the two side surfaces 71b of the retaining groove 71a. In other words, the rotary stop 74c, inserted into the retaining groove 71a, is positioned between the part of the cover film 72 and the part of the buffer film 73, interacting with the side surface 71b of the retaining groove 71a. Therefore, the centrifugal compressor 10 also has the rotary stop 74c, which is formed integrally with the main body 74a. As shown in Fig. 7, the retaining element 74, located in the bearing housing 71 of the first foil bearing 20, is arranged on a side of the bearing housing 71 opposite the electric motor 41. Therefore, the main body 74a of the retaining element 74, which projects from the inner circumferential surface of the bearing housing 71 of the first foil bearing 20, protrudes from a section of the inner circumferential surface of the bearing housing 71 on a side opposite the electric motor 41. As shown in Fig. 8, the retaining element 74, arranged within the bearing housing 71 of the second foil bearing 22, is positioned on a side within the bearing housing 71 opposite the electric motor 41. Therefore, the main body 74a of the retaining element 74, which projects from the inner circumferential surface of the bearing housing 71 of the second foil bearing 22, protrudes from the section of the inner circumferential surface of the bearing housing 71 on the side opposite the electric motor 41. Therefore, the main bodies 74a of the retaining elements 74 protrude from the sections of the respective inner circumferential surfaces of the bearing housing 71 of the first foil bearing 20 and the second foil bearing 22 on the respective sides opposite the electric motor 41. The projection of the main body 74a of the retaining element 74 from the inner circumferential surface of the bearing housing 71 is set to a value that limits deformations of the raised section 73f to the elastic range, preventing them from reaching the plastic range. Therefore, the main body 74a of the retaining element 74 limits the deformations of the raised section 73f to the elastic range, preventing them from reaching the plastic range. The projection of the main body 74a of the retaining element 74 from the inner circumferential surface of the bearing housing 71 is greater than the thickness T1 of the buffer film 73. The buffer film 73, for example, without the main body 74a, is set to have a spring constant at which the buffer film 73 is deformable from the elastic range into the plastic range. As shown in Fig. 1, the centrifugal compressor 10 has a disc-shaped support plate 75 which is provided on the rotating shaft 40. The support plate 75 projects from an outer circumferential surface of the rotating shaft 40. The support plate 75 is pressed / press-fitted into the outer circumferential surface of the rotating shaft 40. The support plate 75 rotates integrally with the rotating shaft 40. The support plate 75 is arranged in the axial bearing receiving chamber 25. An axial bearing 80 is arranged between the first intermediate housing 16 and the support plate 75, and another axial bearing 80 is arranged between the second intermediate housing 17 and the support plate 75. When the support plate 75 rotates as the rotating shaft 40 turns, dynamic pressures are generated between the support plate 75 and the respective axial bearings 80. This causes the support plate 75 to slide off the axial bearings 80, so that the axial bearings 80 rotatably support the support plate 75 without contacting it. The axial bearings 80 are therefore aerodynamic bearings that rotatably support the rotating shaft 40 in the thrust direction. In the centrifugal compressor 10, air is drawn into the motor chamber 18 through the inlet hole 12h. The air drawn into the motor chamber 18 flows through the connecting hole 23, the axial bearing receiving chamber 25, the connecting hole 16b, and into the second chamber-forming recess 16c to reach the first inlet 24. The pressure of the air drawn into the first inlet 24 increases due to the centrifugal force of the first impeller 51. The air is then directed from the first impeller chamber 28 into the first diffuser flow channel 30, and its pressure increases further in the first diffuser flow channel 30. The air flowing through the first diffuser flow channel 30 is expelled / released into the first outlet chamber 29. The air released into the first outlet chamber 29 flows from the first outlet chamber 29 through a channel (not shown) to reach the second inlet 32. The pressure of the air drawn into the second inlet 32 ​​increases due to the centrifugal force of the second impeller 52. The air is then guided from the second impeller chamber 33 into the second diffuser flow channel 35, where its pressure increases further. The air flowing through the second diffuser flow channel 35 is discharged into the second outlet chamber 34. The functionality of the embodiment is described below. For example, the cover film 72 can be displaced radially outwards in the bearing housing 71 due to oscillations / vibrations of the rotating shaft 40, and then the raised sections 73f of the buffer film 73, which are in contact with the outer circumferential surface of the cover film 72, can be excessively pressed through the cover film 72. In this case, the stop surface 74d of the main body 74a of the retaining element 74 abuts the outer circumferential surface of the cover film 72 / rests against it, thus limiting the deformations of the raised sections 73f of the buffer film 73 to the elastic range, so as not to reach the plastic range. In this way, even if, for example,The cover film 72 is displaced outwards in the radial direction of the bearing housing 71 due to the vibrations of the rotating shaft 40, the stop surface 74d of the main body 74a of the retaining element 74 abuts the outer circumferential surface of the cover film 72, thereby limiting the deformations of the raised sections 73f of the buffer film 73 to the elastic range in order not to reach the plastic range. Even if, for example, the cover film 72 and the buffer film 73 move axially on one side towards the opening of the bearing housing 71, the second edge 722c of the cover film 72 and the fixed end section 73a of the buffer film 73 abut / push against that one section of the main body 74a. This reduces the probability that the cover film 72 and the buffer film 73 will protrude axially from the opening of the bearing housing 71 on one side. Even if, for example, the cover film 72 and the buffer film 73 move axially towards an opening of the bearing housing 71 on the other side of the bearing housing 71, the fixed end section 72a of the cover film 72 and the fixed end section 73a of the buffer film 73 abut against the stepped surface 71e / lie against it. This reduces the probability that the cover film 72 and the buffer film 73 will emerge axially from the opening of the bearing housing 71 on the other side of the bearing housing 71. For example, the cover film 72 and the buffer film 73 can move in the circumferential direction of the bearing housing 71. In this case, too, the movements of the cover film 72 and the buffer film 73 in the circumferential direction of the bearing housing 71 are restricted, since the fixed end section 72a of the cover film 72 and the fixed end section 73a of the buffer film 73 are arranged between the side surface 71b of the retaining element 71a and the rotation stop 74c. The embodiment described above offers the advantageous effects described below. (1) For example, even if the cover film 72 is displaced outwards in the radial direction of the bearing housing 71 due to the vibrations of the rotating shaft 40, the stop surface 74d of the main body 74a of the retaining element 74 rests against the outer circumferential surface of the cover film 72, thereby limiting the deformation of the buffer film 73 to the elastic range and preventing it from reaching the plastic range. Since the probability of plastic deformation of the buffer film 73 is reduced, the probability that the first film bearing 20 and the second film bearing 22 will no longer rotatably support the rotating shaft 40 is also reduced. This increases the reliability of the centrifugal compressor 10.(2) The main body 74a is arranged between the outer circumferential surface of the non-overlapping section 72d of the cover sheet 72 and the inner circumferential surface of the bearing housing 71. The position of the main body 74a in the above configuration is suitable for the projection that extends inwards in the radial direction of the bearing housing 71 from the inner circumferential surface of the bearing housing 71. (3) The main body 74a of the retaining element 74 is arranged at the opening of the bearing housing 71, and one section of the main body 74a overlaps with the portion of the cover sheet 72 and the portion of the buffer sheet 73 in the axial direction of the bearing housing 71. In the above configuration, the portion of the cover sheet 72 and the portion of the buffer sheet 73 abut against / behind the one section of the main body 74a, even when the cover sheet 72 and the buffer sheet 73 move, for example, towards the opening of the bearing housing 71.Therefore, the main body 74a reduces the probability of the cover film 72 and the buffer film 73 escaping axially from the bearing housing 71. In other words, the main body 74a of the retaining element 74, which is configured to limit the deformation of the buffer film 73 to the elastic range so that it does not reach the plastic range, also acts as a stopper, preventing the cover film 72 and the buffer film 73 from escaping from the bearing housing 71. Since the main body 74a of the retaining element 74 reduces the probability of the cover film 72 and the buffer film 73 escaping from the bearing housing 71, the first film bearing 20 and the second film bearing 22 support / bearing the rotating shaft 40 stably / rotatably, which further increases the reliability of the centrifugal compressor 10.(4) The centrifugal compressor 10 further comprises the rotation stop 74c, which is formed integrally with the main body 74a of the retaining element 74 and is inserted into the retaining element 71a to be positioned between the portion of the cover film 72 and the portion of the buffer film 73, interacting with the side surface 71b of the retaining element 71a. In the above configuration, the portion of the cover film 72 and the portion of the buffer film 73 are inserted between the side surface 71b of the retaining groove 71a and the rotation stop 74c, even if, for example, there is a probability that the cover film 72 and the buffer film 73 might move in the circumferential direction of the bearing housing 71. This reduces the probability that the cover film 72 and the buffer film 73 will move in the circumferential direction of the bearing housing 71.This eliminates the need to provide a rotation stop as a separate element from the main body 74a of the retaining element 74, thus simplifying the configuration. Since the rotation stop 74c reduces the probability of the cover film 72 and the buffer film 73 moving in the circumferential direction of the bearing housing 71, the first film bearing 20 and the second film bearing 22 rotatably support the rotating shaft 40 in a stable manner, further increasing the reliability of the centrifugal compressor 10. (5) For example, if the rotating shaft 40 generates vibrations, the vibration amplitude of the rotating shaft 40 within the bearing housing 71 increases in a section farther from the electric motor 41. If the rotating shaft 40 generates vibrations, the amount of deformation of the buffer film 73 is likely to increase in a section farther from the electric motor 41.The main body 74a of the retaining element 74, however, projects from the section of the inner circumferential surface of the bearing housing 71 located on the side opposite the electric motor 41. Thus, the main body 74a of the retaining element 74 slightly limits the deformation of the buffer film 73 in a section further away from the electric motor 41 to the elastic range, preventing it from reaching the plastic range. Since the probability of plastic deformation of the buffer film 73 is reduced, the likelihood that the first film bearing 20 and the second film bearing 22 will no longer be able to rotatably support the rotating shaft 40 is also reduced. This increases the reliability of the centrifugal compressor 10.(6) The main bodies 74a of the retaining elements 74 project from the sections of the respective inner circumferential surfaces of the bearing housing 71 of the first foil bearing 20 and the second foil bearing 22, which are located on the respective sides opposite the electric motor 41. In the above configuration, the main bodies 74a of the retaining elements 74 slightly limit the deformations of the buffer foils 73 of the first foil bearing 20 and the second foil bearing 22 to the elastic range in the sections furthest from the electric motor 41, so that the plastic range is not reached, even if, for example, the rotating shaft 40 generates vibrations. As a result, the first foil bearing 20 and the second foil bearing 22 stably support / mount the rotating shaft 40, which further increases the reliability of the centrifugal compressor 10.(7) The portion of the main body 74a of the retaining element 74 is arranged at the positions corresponding to the respective raised sections 73f in the inner circumferential surface of the bearing housing 71. The above configuration easily limits the deformation of the buffer film 73 to the elastic range, so that the plastic range is not reached, in contrast to a case where, for example, the main body 74a is not arranged at the positions corresponding to the respective raised sections 73f in the inner circumferential surface of the bearing housing 71, but is arranged at positions corresponding to the respective bottom sections 73c. ​​(8) When the raised sections 73f of the buffer film 73 are pressed through the cover film 72, the pressed raised sections 73f are deformed, and the deformation is transmitted along the buffer film 73 in the circumferential direction of the bearing housing 71 from the fixed end section 73a as a starting point.The raised sections 73f are more easily deformed at the locations closer to the free end section 73b. However, the portion of the main body 74a of the retaining element 74 is positioned corresponding to the position of the raised sections 73f located on the side near the free end section 73b of the buffer film 73 in the inner circumferential surface of the bearing housing 71. In the configuration described above, even if, for example, the cover film 72 is displaced outwards in the radial direction of the bearing housing 71 due to vibrations of the rotating shaft 40, the deformations of the raised sections 73f at the positions on the side near the free end section 73b, where the deformations occur more easily, are simply limited to the elastic range by the main body 74a of the retaining element 74, so that they do not reach the plastic range.Since the probability of plastic deformation of the buffer film 73 is reduced, the probability that the first film bearing 20 and the second film bearing 22 will no longer rotatably support the rotating shaft 40 is also reduced. This increases the reliability of the centrifugal compressor 10. (9) The main body 74a of the retaining element 74 has a ring shape and extends over the entire circumference of the inner circumferential surface of the bearing housing 71. In this configuration, the main body 74a of the retaining element 74 limits the deformations of all raised sections 73f to the elastic range, so that the plastic range is not reached, thereby reducing the probability of plastic deformation of the buffer film 73 in a simple manner.This further reduces the probability that the first foil bearing 20 and the second foil bearing 22 will no longer be able to rotatably support the rotating shaft 40, thus further increasing the reliability of the centrifugal compressor 10. (10) Since the main body 74a of the retaining element 74 reduces the probability of plastic deformation of the buffer foil 73, the movement of the first impeller 51 and the second impeller 52 is reduced even if, for example, the rotating shaft 40 generates vibrations or the centrifugal compressor 10 itself generates vibrations. This eliminates the need to ensure a specific peak clearance between the first impeller 51 and the housing 11 and a specific peak clearance between the second impeller 52 and the housing 11 to prevent the outer circumference of the first impeller 51 from colliding with the housing 11 and the outer circumference of the second impeller 52 from colliding with the housing 11.This reduces the deterioration of the compression efficiency of the centrifugal compressor 10. The following modifications can be made to the embodiment described above. The embodiment described above and the following modifications can be combined, provided this does not lead to technical inconsistencies. As shown in Fig. 9, a plurality of projections 81 can extend radially inwards from portions of the inner circumferential surface of the bearing housing 71. The projections 81 are arranged axially at the opening of the bearing housing 71 on one side of the bearing housing 71. The projections 81 are arranged at positions that, viewed axially on the inner circumferential surface of the bearing housing 71, correspond to the associated raised sections 73f. The projections 81 are arranged axially adjacent to the buffer film 73. The projections 81 are arranged between the outer circumferential surface of the non-overlapping section 72d of the cover film 72 and the inner circumferential surface of the bearing housing 71. The embodiment shown in Fig. 9 has three projections 81 that protrude from the inner circumferential surface of the bearing housing 71. Therefore, in the embodiment shown in Fig. 9, a plurality of projections 81 protrude from the portions of the inner circumferential surface of the bearing housing 71 and are arranged at intervals in the circumferential direction. The end faces of the projections 81 in the projection direction correspond to stop surfaces 81d, which limit the deformation of the buffer film 73 by abutting the outer circumferential surface of the cover film 72 to the elastic range, so that it does not reach the plastic range when the cover film 72 is displaced outwards in the radial direction of the bearing housing 71. Therefore, each of the projections 81 has the stop surface 81d. The stop surface 81d of the projection 81 is arcuate so that it extends along the shape of the cover film 72 when the cover film 72 is displaced.A width H1 of each projection 81 in the circumferential direction of the bearing housing 71 is greater than a width H2 of each raised section 73f in the circumferential direction of the bearing housing 71. In the configuration described above, the stiffness of the projections 81 is increased compared to a case where, for example, the width H1 of each projection 81 in the circumferential direction of the bearing housing 71 is smaller than the width H2 of each raised section 73f in the circumferential direction of the bearing housing 71. Thus, the projections 81 effectively limit the deformations of the raised section 73f to the elastic range, preventing them from reaching the plastic range. Therefore, the first foil bearing 20 and the second foil bearing 22 stably support / support the rotating shaft 40, further increasing the reliability of the centrifugal compressor 10. As shown in Fig. 10, in the prior art the projections 81A are not arranged at the opening of the bearing housing 71 and do not overlap with parts of the cover film 72 and parts of the buffer film 73 in the axial direction of the bearing housing 71. Here, the projections 81A can be arranged between the inner circumferential surface of the bearing housing 71 and the associated raised section 73f. In this case, the projections 81A are not arranged adjacent to the buffer film 73 in the axial direction. As described above, the projections 81A need not be axially adjacent to the buffer film 73 and need not be arranged between the outer circumferential surface of the non-overlapping section 72d of the cover film 72 and the inner circumferential surface of the bearing housing 71.The end faces of the projections 81A in the projection direction correspond to stop surfaces 81D, which restrict the deformation of the buffer film 73 to the elastic range, so as not to reach the plastic range, by bearing against an outer circumferential surface of the buffer film 73, which corresponds to an outer surface of the buffer film 73 when the cover film 72 is displaced outwards in the radial direction of the bearing housing 71. Therefore, each of the projections 81A has the stop surface 81D. For example, the cover film 72 can be displaced outwards in the radial direction of the bearing housing 71 due to the vibrations of the rotating shaft 40, and then the raised sections 73f of the buffer film 73, which are in contact with the outer circumferential surface of the cover film 72, can be excessively pressed by the cover film 72. At this point, the stop surfaces 81D of the projections 81A rest against the outer circumferential surface of the buffer film 73, thus limiting the deformation of the buffer film 73 to the elastic range so as not to reach the plastic range. In this embodiment, the centrifugal compressor 10 does not need to have the rotation stop 74c.- In this embodiment, the main body 74a of the retaining element 74 can project from a section of the inner circumferential surface of the bearing housing 71 located on one side near the electric motor 41, instead of projecting from the section of the inner circumferential surface of the bearing housing 71 located on the side opposite the electric motor 41. - In this embodiment, the main body 74a of the retaining element 74 projects from the section of the inner circumferential surface of the bearing housing 71 located on the side opposite the electric motor 41, and can also project from the section of the inner circumferential surface of the bearing housing 71 located on the side near the electric motor 41.- In this embodiment, the main body 74a of the retaining element 74, which projects from the inner circumferential surface of the bearing housing 71 of the first foil bearing 20 or the second foil bearing 22, can project from the section of the inner circumferential surface of the bearing housing 71 that is located on the side near the electric motor 41. - In this embodiment, the main body 74a of the retaining element 74 need not project from the position corresponding to one of the raised sections 73f of the buffer foil 73, which is located on the side near the free end section 73b of the buffer foil 73 in the inner circumferential surface of the bearing housing 71, when viewed in the axial direction of the bearing housing 71. - In this embodiment, an annular projection corresponding to the main body 74a of the retaining element 74 can be formed integrally with the inner circumferential surface of the bearing housing 71.In other words, the centrifugal compressor 10 does not need to have the main body 74a of the retaining element 74 as a separate element from the bearing housing 71 in order for it to correspond to the annular projection. In this embodiment, the buffer film 73 does not need to have a cylindrical shape, but can, for example, have an arcuately curved plate shape. The centrifugal compressor 10 can have a configuration in which a plurality of buffer films 73, each having the arcuate plate shape, are arranged circumferentially along the inner circumferential surface of the bearing housing 71. In this embodiment, for example, two buffer films 73 can be arranged side by side in the axial direction of the bearing housing 71 between the inner circumferential surface of the bearing housing 71 and the cover film 72.The buffer films 73 adjacent to one another in the axial direction of the bearing housing 71 can be spaced apart from each other in the axial direction of the bearing housing 71. In this case, a section of the cover film 72 that overlaps with the space between the two buffer films 73 in the radial direction of the bearing housing 71 is a non-overlapping section that extends further in the axial direction of the bearing housing 71 than the two buffer films 73 and does not overlap with the buffer films 73 in the radial direction of the bearing housing 71. The projection that extends radially inwards from the inner circumferential surface of the bearing housing 71 can then be located between the outer circumferential surface of the non-overlapping section and the inner circumferential surface of the bearing housing 71.- In this embodiment, the projection extending radially inwards from the inner circumferential surface of the bearing housing 71 can be arranged at positions corresponding to the respective base sections 73c in the inner circumferential surface of the bearing housing 71, instead of at positions corresponding to the respective raised sections 73f. - In this embodiment, the centrifugal compressor 10 need not, for example, have the second impeller 52. - In this embodiment, the fluid compressed by the first impeller 51 and the second impeller 52 is not limited to air. The centrifugal compressor 10 can be used for any object and can compress any fluid. For example, the centrifugal compressor 10 can be used for an air conditioning system and can compress a refrigerant. Furthermore, the centrifugal compressor 10 can be attached to any object, in particular to a vehicle.- In this embodiment, the fluid machine can have a scroll compressor with a scroll mechanism as the actuating element, configured to expel the fluid by rotating the shaft. Alternatively, the fluid machine can also use a Roots pump with two rotors as the actuating element.

Claims

Fluid machine (10) comprising: a rotary shaft (40); an actuating element (51, 52) configured to discharge fluid by rotation of the rotary shaft (40); a housing (11) accommodating the rotary shaft (40) and the actuating element (51, 52); and a foil bearing (20, 22) arranged in the housing (11) and rotatably supporting the rotary shaft (40), the foil bearing (20, 22) comprising: a bearing housing (71) with a cylindrical shape; a cover foil (72) arranged between an inner circumferential surface of the bearing housing (71) and the rotary shaft (40);and a buffer film (73) arranged between the inner circumferential surface of the bearing housing (71) and the cover film (72) and elastically supporting the cover film (72), characterized in that the bearing housing (71) has a projection (74a, 81) which extends inwards in a radial direction of the bearing housing (71) from the inner circumferential surface of the bearing housing (71), and the projection (74a, 81) has a stop surface (74d) which is configured to limit deformation of the buffer film (73) to an elastic range, so that it does not reach a plastic range by abutting an outer surface of the cover film (72) when the cover film (72) is displaced outwards in the radial direction of the bearing housing (71). Fluid machine (10) according to claim 1, characterized in that the cover film (72) has a non-overlap section (72d) which extends further in the axial direction of the bearing housing (71) than the buffer film (73) and which is not overlapped by the buffer film (73) in the radial direction of the bearing housing (71), and the projection (74a, 81) is arranged in the axial direction next to the buffer film (73) and between an outer surface of the non-overlap section (72d) and the inner circumferential surface of the bearing housing (71). Fluid machine (10) according to claim 1 or 2, characterized in that the projection (74a, 81) is arranged at an opening of the bearing housing (71), and a section of the projection (74a, 81) overlaps with a part of the cover film (72) and a part of the buffer film (73) in the axial direction of the bearing housing (71). Fluid machine (10) according to claim 3, characterized in that the bearing housing (71) has a retaining groove (71a) in the inner circumferential surface of the bearing housing (71), the part of the cover film (72) and the part of the buffer film (73) are inserted into the retaining groove (71a), and the fluid machine (10) further comprises a rotation stop (74c) which is formed integrally with the projection (74a, 81) and is inserted into the retaining groove (71a) in order to be inserted between the part of the cover film (72) and the part of the buffer film (73) in conjunction with a side surface (71b) of the retaining groove (71a). Fluid machine (10) according to one of claims 1 to 4, characterized in that the fluid machine (10) has an electric motor (41) designed to rotate the rotating shaft (40), and the projection (74a, 81) protrudes from a section of the inner circumferential surface of the bearing housing (71) located on a side opposite the electric motor (41). Fluid machine (10) according to claim 5, characterized in that the foil bearing (20, 22) has a first foil bearing (20) and a second foil bearing (22) between which the electric motor (41) is arranged in an axial direction of the rotating shaft (40), and the projection (81) of both the first foil bearing (20) and the second foil bearing (22) projects from the section of the inner circumferential surface of the bearing housing (71) which is located on the side opposite the electric motor (41). Fluid machine (10) according to one of claims 1 to 6, characterized in that the buffer film (73) has a cylindrical shape, wherein the buffer film (73) comprises: a bottom section (73c) which is in contact with the inner circumferential surface of the bearing housing (71); and a raised section (73f) which is in contact with an outer circumferential surface of the cover film (72) and is elastically deformable with an outward displacement of the cover film (72) in the radial direction of the bearing housing (71), and the projection (81) is arranged at a position corresponding to the raised section (73f) in the inner circumferential surface of the bearing housing (71). Fluid machine (10) according to claim 7, characterized in that the buffer film (73) comprises: a fixed end section (73a) which is an end section of the buffer film (73) in a circumferential direction of the buffer film (73); and a free end section (73b) which is the other end section of the buffer film (73) in the circumferential direction of the buffer film (73); a plurality of the bottom sections (73c) and a plurality of the raised sections (73f) are arranged alternately in a circumferential direction of the bearing housing (71) starting from the fixed end section (73a) to the free end section (73b) of the buffer film (73); and the projection (81) is arranged at a position corresponding to the raised section (73f) which is located on one side near the free end section (73b) of the buffer film (73) in the inner circumferential surface of the bearing housing (71). Fluid machine (10) according to one of claims 1 to 6, characterized in that the projection (74a) has a ring shape, and the projection (74a) extends over an entire circumference of the inner circumferential surface of the bearing housing (71). Fluid machine (10) according to claim 7, characterized in that a plurality of the bottom sections (73c) and a plurality of the raised sections (73f) are arranged alternately in a circumferential direction of the bearing housing (71), a plurality of the projections (81) project in a circumferential direction of the bearing housing (71) at intervals from the sections of the inner circumferential surface of the bearing housing (71), and a width (H1) of each of the projections (81) in the circumferential direction of the bearing housing (71) is greater than a width (H2) of each of the raised sections (73f) in the circumferential direction of the bearing housing (71).

Images