Centrifugal compressor

Abstract

To provide a centrifugal compressor capable of suppressing influence of rotatably supporting a rotational shaft in a non-contact manner, in a radial foil bearing.SOLUTION: A centrifugal compressor has a seal member 100 that is provided at an axial end part of a radial foil bearing 20 and prevents fluid leakage from an impeller chamber to a motor chamber. The seal member 100 has: an annular plate part 101 into which a rotational shaft 40 is inserted, and which covers a radial outer periphery of a top foil 72 from a radial inner periphery to a radial outer periphery of a bearing housing part 18; and a locking part 102 which protrudes from the annular plate part 101 in an axial direction X toward the radial foil bearing 20, and is locked to an outer peripheral surface of the top foil 72.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a centrifugal compressor.

Background Art

[0002] A centrifugal compressor includes a rotating shaft, a motor that rotates the rotating shaft, an impeller that compresses a fluid by rotating integrally with the rotating shaft, and a housing that houses the rotating shaft and the impeller. The housing is formed with an impeller chamber that houses the impeller and a motor chamber that houses the motor. The centrifugal compressor also includes a radial foil bearing. The radial foil bearing is disposed between the impeller chamber and the motor chamber in the housing and supports the rotating shaft in a non-contact and rotatable manner. The radial foil bearing is fixed to a bearing housing portion provided in the housing. The bearing housing portion is disposed at a position between the impeller chamber and the motor chamber in the housing.

[0003] The radial foil bearing has a top foil and a bump foil. The top foil is disposed between the bearing housing portion and the rotating shaft and supports the rotating shaft in a non-contact state and rotatably when the rotating shaft rotates. The bump foil is disposed between the bearing housing portion and the top foil and elastically supports the top foil.

[0004] The centrifugal compressor has a sealing function for suppressing leakage of fluid from the impeller chamber, which is a high-pressure chamber having a higher pressure than the motor chamber, to the motor chamber. For example, in the electric turbo compressor described in Patent Document 1, a sealing portion that exhibits the above sealing function is provided on the top foil. The sealing portion is integrally formed on the top foil so as to extend in a flange shape radially outward from the top foil. The sealing portion is fitted into a recess formed in the housing. The sealing portion is located between the high-pressure chamber and the motor chamber.

[0005] And in the electric turbo compressor described in Patent Document 1, the pressure inside the high-pressure chamber is applied to the seal portion. Then, the seal portion is biased and seated in the recess. As a result, the seal portion seals between the motor chamber and the high-pressure chamber.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] By the way, in the seal portion described in Patent Document 1, when the seal portion is provided on the top foil, there is a risk that the shape of the top foil may change. If the shape of the top foil changes, it may affect the ability to rotatably support the rotating shaft in a non-contact state in the radial foil bearing, which is not preferable.

Means for Solving the Problems

[0008] A centrifugal compressor for solving the above problems includes a rotating shaft driven by a motor, an impeller that compresses fluid by rotating integrally with the rotating shaft, a housing that houses the rotating shaft and forms a motor chamber for housing the motor and an impeller chamber for housing the impeller, a radial foil bearing disposed inside the housing and rotatably supporting the rotating shaft between the impeller chamber and the motor chamber in the axial direction of the rotating shaft, and a seal member provided at an axial end of the radial foil bearing to suppress leakage of fluid from the impeller chamber to the motor chamber. The housing has a bearing housing portion to which the radial foil bearing is fixed. The radial foil bearing includes a top foil disposed between the bearing housing portion and the rotating shaft, and a bump foil disposed between the bearing housing portion and the top foil and elastically supporting the top foil. The seal member has an annular plate portion through which the rotating shaft passes and that covers a gap from a radially outer periphery of the top foil to a radially outer peripheral position from a radially inner peripheral position of the bearing housing portion, and a locking portion that projects in the axial direction of the rotating shaft from the annular plate portion toward the radial foil bearing and is locked to the radially outer periphery of the top foil.

[0009] According to this, since the annular plate portion of the seal member can cover the gap from the radially outer periphery of the top foil to the radially inner periphery of the bearing housing portion, the annular plate portion can suppress leakage of high-pressure fluid from the impeller chamber to the motor chamber. Further, since the seal member is locked to the radially outer periphery of the top foil by the locking portion, when the rotating shaft is displaced in the radial direction, the seal member is also displaced in the same direction together with the top foil. Thereby, even when the rotating shaft is displaced in the radial direction due to external excitation or the like, the gap from the radially outer periphery of the top foil to the radially inner periphery of the bearing housing portion can be covered, so that the annular plate portion can suppress leakage of high-pressure fluid from the impeller chamber to the motor chamber.

[0010] Further, the top foil and the seal member are configured as separate bodies. Therefore, for example, when a configuration for covering a gap is integrally formed on the top foil by bending the top foil, there is no longer a risk of the shape of the top foil changing due to providing the configuration for covering the gap. As a result, in the radial foil bearing, it is possible to suppress the influence on rotatably supporting the rotating shaft in a non-contact state.

[0011] In the centrifugal compressor, the bearing housing portion opens toward the impeller chamber and the motor chamber, and has a slit into which a fixed end of at least one of the top foil and the bump foil is inserted. The annular plate portion may cover an outer peripheral position of the slit along the radial direction of the bearing housing portion.

[0012] According to this, leakage of fluid from the impeller chamber to the motor chamber through the slit can be suppressed by the annular plate portion. In the centrifugal compressor, the locking portion may be formed as a plurality of locking pieces provided at intervals in the circumferential direction of the annular plate portion.

[0013] According to this, it becomes easy to create the locking portion on the seal member. In the centrifugal compressor, the bump foil has a plurality of bump foil portions arranged in the circumferential direction of the bearing housing portion. Each of the plurality of bump foil portions has a fixed end fixed to the bearing housing portion at one end in the circumferential direction of the bump foil portion, and a free end at the other end in the circumferential direction of the bump foil portion. The locking portion may be inserted between the fixed end and the free end of the adjacent bump foil portions in the circumferential direction.

[0014] According to this, for example, in the case where the locking portion is a cylindrical shape extending over the entire circumferential direction of the bearing housing portion, in order to lock the locking portion to the radially outer periphery of the top foil, it is necessary to provide a configuration for the cylindrical locking portion to avoid interference with the bump foil. However, by forming the locking portion as a locking piece, the locking portion can be locked to the radially outer periphery of the top foil by utilizing the gap between the fixed end and the release end. Therefore, unlike the case where the locking portion is formed as a cylindrical shape extending over the entire circumferential direction of the bearing housing portion, it is possible to lock the locking portion to the radially outer periphery of the top foil without requiring a configuration for avoiding interference between the locking portion and the bump foil.

[0015] In the centrifugal compressor, the seal member includes a top foil contact portion that contacts the axial end face of the top foil on the inner peripheral side of the locking portion in the radial direction of the seal member, and the top foil contact portion may extend between the radially outer peripheral position and the radially inner peripheral position of the top foil.

[0016] According to this, the top foil contact portion can suppress the leakage of fluid along the outer peripheral surface of the top foil. Thereby, the function of suppressing the leakage of high-pressure fluid from the impeller chamber to the motor chamber can be improved.

[0017] The locking portion is cylindrical, and a fitting groove into which the fixed end of the top foil to the bearing housing portion fits may be formed in the locking portion. According to this, for example, compared with the case where the locking portions are arranged at intervals in the circumferential direction, the locking area of the locking portion with respect to the radially outer periphery of the top foil can be increased. Therefore, the seal member can easily follow the top foil. Further, the fitting groove can avoid interference between the locking portion and the fixed end of the top foil to the bearing housing portion.

[0018] In the centrifugal compressor, the axial length of the top foil is longer than the axial length of the bump foil, and the locking portion may extend between the end face in the axial direction of the bump foil and the end face in the axial direction of the top foil and be locked to the outer peripheral surface of the top foil.

[0019] According to this, by adjusting the axial length of the bump foil, the locking portion can be locked to the radially outer periphery of the top foil.

Advantages of the Invention

[0020] According to this, in a radial foil bearing, the influence on rotatably supporting a rotating shaft in a non-contact state can be suppressed.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Best Mode for Carrying Out the Invention

[0022] (First Embodiment) Hereinafter, a first embodiment in which a centrifugal compressor is embodied will be described with reference to FIGS. 1 to 7. <Basic Configuration of Centrifugal Compressor 10> As shown in FIG. 1, the centrifugal compressor 10 includes a housing 11, a rotating shaft 40, two radial foil bearings 20, a first impeller 34 as an impeller, a second impeller 35 as an impeller, and a motor 39. Further, the centrifugal compressor 10 includes a seal member 100 provided on each radial foil bearing 20.

[0023] The centrifugal compressor 10 of the present embodiment is used as a centrifugal compressor that compresses air as a fluid containing oxygen supplied to the fuel cell of a fuel cell vehicle. The housing 11 is made of a metal material. Examples of the material of the housing 11 include aluminum. The housing 11 has a motor housing 12, a first impeller housing 13, a second impeller housing 14, a first plate 15, a second plate 16, and a third plate 17.

[0024] The motor housing 12 has a cylindrical peripheral wall 12a and a flat end wall 12b located at the first end of the peripheral wall 12a. The first plate 15 closes the second end of the motor housing 12. A motor chamber 51 is defined by the inner surface of the motor housing 12 and the first plate 15. The motor 39 is accommodated in the motor chamber 51. Therefore, a motor chamber 51 for accommodating the motor 39 is formed in the housing 11.

[0025] The first plate 15 has a bearing housing portion 18. A recess 15c is formed in an end face 15b of the first plate 15 on the side opposite to the motor housing 12. The bearing housing portion 18 provided on the first plate 15 extends cylindrically from the first plate 15 toward the motor 39. A recess 15d for the first shaft is formed in the first plate 15. The recess 15d for the first shaft is recessed from the recess 15c toward the bearing housing portion 18.

[0026] Also, the end wall 12b of the motor housing 12 has a bearing housing portion 18. The bearing housing portion 18 provided on the end wall 12b extends cylindrically from the end wall 12b toward the motor 39. A recess 12c for the second shaft is formed in the end wall 12b of the motor housing 12. The recess 12c for the second shaft is recessed from the end face of the end wall 12b toward the bearing housing portion 18.

[0027] The second plate 16 is connected to the first plate 15. A first shaft insertion hole 16a is formed in a central portion of the second plate 16. A thrust bearing accommodation chamber 52 is defined by an inner surface partitioning the recess 15c in the first plate 15 and the second plate 16.

[0028] The first impeller housing 13 is cylindrical and has a circular hole-shaped suction port 13a through which air is inhaled. The first impeller housing 13 is connected to the second plate 16. Between the first impeller housing 13 and the second plate 16, a first impeller chamber 13b, a discharge chamber 13c, and a first diffuser flow path 13d are formed.

[0029] The first impeller chamber 13b is formed in the housing 11. The first impeller chamber 13b communicates with the suction port 13a. The discharge chamber 13c extends around the first impeller chamber 13b around the axis of the suction port 13a. The first diffuser flow path 13d communicates the first impeller chamber 13b and the discharge chamber 13c. The first impeller chamber 13b communicates with the first shaft insertion hole 16a of the second plate 16.

[0030] The first impeller housing 13 has a first shroud surface 53a. The first shroud surface 53a cooperates with the second plate 16 to define the first impeller chamber 13b. The first shroud surface 53a is frustoconical in shape.

[0031] The third plate 17 is connected to the end wall 12b of the motor housing 12. A second shaft insertion hole 17a is formed in the central portion of the third plate 17. The second impeller housing 14 is cylindrical with a circular hole-shaped discharge port 14a through which air is inhaled. The second impeller housing 14 is connected to the end face of the third plate 17 on the side opposite to the motor housing 12. The discharge port 14a opens at the end face of the second impeller housing 14 on the side opposite to the third plate 17. Between the second impeller housing 14 and the third plate 17, a second impeller chamber 14b, a suction chamber 14c, and a second diffuser flow path 14d are formed.

[0032] The second impeller chamber 14b is formed in the housing 11. The second impeller chamber 14b communicates with the discharge port 14a. The suction chamber 14c extends around the second impeller chamber 14b and around the axis of the discharge port 14a. The second diffuser flow path 14d communicates the second impeller chamber 14b and the suction chamber 14c. The second impeller chamber 14b communicates with the second shaft insertion hole 17a.

[0033] The second impeller housing 14 has a second shroud surface 53b. The second shroud surface 53b cooperates with the third plate 17 to define the second impeller chamber 14b. The second shroud surface 53b is frustoconical in shape.

[0034] <Rotating shaft 40> The rotating shaft 40 is accommodated within the housing 11. The rotating shaft 40 is driven by the motor 39. A part of the rotating shaft 40 is located in the first impeller chamber 13b and the second impeller chamber 14b. Thereby, the rotating shaft 40 is accommodated within the first impeller housing 13 and the second impeller housing 14.

[0035] The rotating shaft 40 passes through these in the order of the first impeller chamber 13b, the first shaft insertion hole 16a, the recess 15c of the first plate 15, the recess 15d for the first bearing, the inside of the bearing housing portion 18 provided on the first plate 15, the motor chamber 51, the inside of the bearing housing portion 18 provided on the motor housing 12, the recess 12c for the second bearing, the second shaft insertion hole 17a, and the second impeller chamber 14b.

[0036] In the following description, the direction in which the axis SL of the rotating shaft 40 extends is referred to as the "axial direction of the rotating shaft 40". The direction in which the diameter of the rotating shaft 40 extends is referred to as the "radial direction of the rotating shaft 40". The axial direction of the rotating shaft 40 is also referred to as the axial direction X. The radial direction of the rotating shaft 40 is also referred to as the radial direction Y.

[0037] The rotating shaft 40 includes a disk-shaped support plate 33. The support plate 33 protrudes from the outer peripheral surface of the rotating shaft 40. The support plate 33 is press-fitted onto the outer peripheral surface of the rotating shaft 40. The support plate 33 rotates integrally with the rotating shaft 40. The support plate 33 is disposed in the thrust bearing housing chamber 52.

[0038] The support plate 33 is supported by a thrust bearing 80. <The first impeller 34> The first impeller 34 is made of metal. Examples of the material of the first impeller 34 include aluminum. The first impeller 34 is connected to the first end portion 30a of the rotating shaft 40. The first impeller 34 is an impeller that rotates integrally with the rotating shaft 40. The first impeller 34 is housed in the first impeller chamber 13b.

[0039] The first impeller 34 has a frustum of a cone shape. The first impeller 34 gradually decreases in diameter from the first rear surface 34a, which is the rear surface of the first impeller 34, toward the first tip surface 34b, which is the tip surface of the first impeller 34. The first rear surface 34a faces the second plate 16 in the axial direction X. From the first rear surface 34a to the first tip surface 34b, a first shroud surface 53a extends along the outer periphery of the first impeller 34. Thereby, the first shroud surface 53a covers the outer periphery of the first impeller 34. The first rear surface 34a faces the second plate 16 in the axial direction X. The first impeller 34 compresses air as a fluid by rotating integrally with the rotating shaft 40.

[0040] <The second impeller 35> The second impeller 35 is made of metal. Examples of the material of the second impeller 35 include aluminum. The second impeller 35 is connected to the second end portion 30b of the rotating shaft 40. The second impeller 35 is an impeller that rotates integrally with the rotating shaft 40. The second impeller 35 is housed in the second impeller chamber 14b.

[0041] The second impeller 35 has a frustum of a cone shape. The second impeller 35 gradually decreases in diameter from the second rear surface 35a, which is the rear surface of the second impeller 35, toward the second tip surface 35b, which is the tip surface of the second impeller 35. The second rear surface 35a faces the third plate 17 in the axial direction X. From the second rear surface 35a to the second tip surface 35b, a second shroud surface 53b extends along the outer periphery of the second impeller 35. Thereby, the second shroud surface 53b covers the outer periphery of the second impeller 35. The second impeller 35 compresses air as a fluid by rotating integrally with the rotating shaft 40.

[0042] <The first high-pressure passage 90 and the second high-pressure passage 91> The first high-pressure passage 90 is formed by being sandwiched between the first rear surface 34a and the first impeller-side end surface 16b of the second plate 16, and communicates with the first shaft insertion hole 16a. The second high-pressure passage 91 is formed by being sandwiched between the second rear surface 35a and the second impeller-side end surface 17b of the third plate 17, and communicates with the second shaft insertion hole 17a. Therefore, the first high-pressure passage 90 communicates the first diffuser flow path 13d and the first shaft insertion hole 16a. Also, the second high-pressure passage 91 communicates the second diffuser flow path 14d and the second shaft insertion hole 17a.

[0043] <Configuration of the Radial Foil Bearing 20> The radial foil bearings 20 are fixed to the respective bearing housing portions 18. Therefore, the two radial foil bearings 20 are disposed inside the housing 11. Also, one of the two radial foil bearings 20 rotatably supports the rotating shaft 40 between the first impeller chamber 13b and the motor chamber 51, and the other of the two radial foil bearings 20 rotatably supports the rotating shaft 40 between the second impeller chamber 14b and the motor chamber 51. The two radial foil bearings 20 have the same configuration.

[0044] The radial foil bearing 20 supports the rotating shaft 40 in a state of being in contact with the rotating shaft 40 until the rotational speed of the rotating shaft 40 reaches the floating rotational speed at which the rotating shaft 40 floats due to the radial foil bearing 20. When the rotating shaft 40 rotates, a dynamic pressure is generated between the rotating shaft 40 and the radial foil bearing 20. When the rotational speed of the rotating shaft 40 reaches the floating rotational speed, the generated dynamic pressure causes the rotating shaft 40 to float with respect to the radial foil bearing 20. Thereby, the radial foil bearing 20 rotatably supports the rotating shaft 40 in a non-contact state with respect to the rotating shaft 40.

[0045] Next, the specific configuration of the radial foil bearing 20 will be described. As shown in FIGS. 2 and 3, the radial foil bearing 20 has a top foil 72 and a bump foil 73. Each of the two radial foil bearings 20 is fixed inside the bearing housing portion 18. Therefore, the housing 11 has a bearing housing portion 18 to which the radial foil bearing 20 is fixed.

[0046] <bearing housing portion 18> Since the bearing housing portion 18 provided on the first plate 15 and the bearing housing portion 18 provided on the motor housing 12 have the same configuration, one of the bearing housing portions 18 will be described as an example.

[0047] The bearing housing portion 18 is cylindrical. The circumferential direction of the bearing housing portion 18 coincides with the circumferential direction of the radial foil bearing 20. In the following description, the circumferential direction of the radial foil bearing 20 and the bearing housing portion 18 is referred to as the circumferential direction B.

[0048] The axis of the bearing housing portion 18 coincides with the axis SL of the rotating shaft 40. Therefore, the axial direction X is also the axial direction of the bearing housing portion 18. The radial direction Y is also the radial direction of the bearing housing portion 18. An insertion hole 18h through which the rotating shaft 40 is inserted is formed in the bearing housing portion 18.

[0049] As shown in FIG. 1, the bearing housing portion 18 has a first end face 18A and a second end face 18B. The first end face 18A and the second end face 18B are end faces in the axial direction X of the bearing housing portion 18. The first end face 18A is an end face located on one side in the axial direction X of the bearing housing portion 18, and the second end face 18B is an end face located at the other end in the axial direction X of the bearing housing portion 18. The first end face 18A of the bearing housing portion 18 on the first plate 15 is an end face exposed in the first bearing recess 15d, and the first end face 18A of the bearing housing portion 18 on the motor housing 12 is an end face exposed in the second bearing recess 12c. The second end face 18B of each bearing housing portion 18 is an end face exposed in the motor chamber 51.

[0050] As shown in FIGS. 2 and 3, the inner peripheral surface 18g of the bearing housing portion 18 is a cylindrical surface that defines the insertion hole 18h. The first slit 18a, the second slit 18b, the third slit 18c, and the fourth slit 18d are formed in the inner peripheral surface 18g of the bearing housing portion 18. The first slit 18a, the second slit 18b, the third slit 18c, and the fourth slit 18d are arranged in the circumferential direction B of the bearing housing portion 18 in this order. The intervals in the circumferential direction B between the first slit 18a and the second slit 18b, between the second slit 18b and the third slit 18c, and between the third slit 18c and the first slit 18a are equal. Also, these intervals are larger than the interval in the circumferential direction B between the fourth slit 18d and the third slit 18c. Each of the first to fourth slits 18a to 18d is provided over the entire length in the axial direction X of the bearing housing portion 18. Each of the first to fourth slits 18a to 18d opens toward the first impeller chamber 13b or the second impeller chamber 14b at the first end face 18A of the bearing housing portion 18. Each of the first to fourth slits 18a to 18d opens toward the motor chamber 51 at the second end face 18B of the bearing housing portion 18.

[0051] <Top foil 72> The top foil 72 is cylindrical. The top foil 72 of the present embodiment is substantially cylindrical. The top foil 72 is located inside the bearing housing portion 18. The top foil 72 extends in the circumferential direction B inside the bearing housing portion 18. The top foil 72 is thin plate-shaped. Specifically, the top foil 72 is formed of a strip-shaped metal plate material made of a flexible metal such as stainless steel, for example. The top foil 72 is formed by bending this metal plate material into a cylindrical shape such that the longitudinal direction extends in the circumferential direction B of the bearing housing portion 18 and the short-side direction extends in the axial direction X.

[0052] At both ends of the top foil 72 in the circumferential direction B, top foil fixed ends 72a are provided. Each top foil fixed end 72a is formed by bending a metal plate outward in the radial direction Y of the top foil 72. Each top foil fixed end 72a is in the shape of a rectangular flat plate extending perpendicular to the circumferential direction B. The dimension of each top foil fixed end 72a in the axial direction X is the same as the dimension of the top foil 72 in the axial direction X. One top foil fixed end 72a is inserted into the first slit 18a, and the other top foil fixed end 72a is inserted into the fourth slit 18d. By inserting each top foil fixed end 72a into each slit 18a, 18d, the movement of the top foil 72 in the circumferential direction B is suppressed.

[0053] The top foil 72 is arranged outside the rotation axis 40 in the radial direction Y. Therefore, the top foil 72 is arranged between the bearing housing portion 18 and the rotation axis 40 in the radial direction Y. The top foil 72 faces the rotation axis 40 in the radial direction Y. The top foil 72 has a bearing surface 72s and a bump foil surface 72t. The bearing surface 72s is the inner surface in the radial direction Y, and the bump foil surface 72t is the outer surface in the radial direction Y. The bearing surface 72s faces the circumferential surface of the rotation axis 40, and the bump foil surface 72t faces the bump foil 73 described later.

[0054] <Bump foil 73> The bump foil 73 has three bump foil portions 73c divided in the circumferential direction B of the bearing housing portion 18. The three bump foil portions 73c constituting the bump foil 73 are also referred to as a plurality of bump foil portions 73c hereinafter. The circumferential dimensions of the plurality of bump foil portions 73c may be substantially the same as each other, or may be different from each other in part or in whole. The dimension of each bump foil portion 73c in the axial direction X is the same as the dimension of the top foil 72 in the axial direction X.

[0055] Each bump foil portion 73c includes a plurality of peak portions 81 and a plurality of valley portions 82. Each peak portion 81 contacts the bump foil surface 72t. Each valley portion 82 contacts the inner peripheral surface 18g of the bearing housing portion 18. The peak portions 81 and the valley portions 82 are alternately arranged in the circumferential direction B of the bearing housing portion 18.

[0056] The valley portion 82 protrudes away from the bump foil surface 72t in the radial direction Y and is arcuately curved so as to bulge toward the bearing housing portion 18. The peak portion 81 protrudes from the end of the valley portion 82 in the circumferential direction B toward the bump foil surface 72t and is arcuately curved so as to bulge toward the top foil 72. Each bump foil portion 73c elastically supports the top foil 72 as the peak portion 81 and the valley portion 82 extend in the circumferential direction B. The plurality of bump foil portions 73c may each have the same number of peak portions 81, or the number of peak portions 81 provided in some or all of them may be different from each other. The plurality of bump foil portions 73c may each have the same number of valley portions 82, or the number of valley portions 82 provided in some or all of them may be different from each other.

[0057] Each of the plurality of bump foil portions 73c has a fixed end 73d fixed to the bearing housing portion 18 at one end in the circumferential direction B of the bump foil portion 73c and a free end 73e at the other end in the circumferential direction B of the bump foil portion 73c. In each bump foil portion 73c, the end opposite to the fixed end 73d in the circumferential direction B is the free end 73e.

[0058] As shown in FIG. 3, the fixed end 73d of one of the three bump foil portions 73c is inserted into the first slit 18a together with one of the top foil fixed ends 72a. Counterclockwise, the fixed end 73d of the second bump foil portion 73c adjacent to the first bump foil portion 73c is inserted into the second slit 18b. Counterclockwise, the fixed end 73d of the third bump foil portion 73c adjacent to the second bump foil portion 73c is inserted into the third slit 18c. Therefore, the bearing housing portion 18 has the first to third slits 18a to 18c as slits into which the fixed ends 73d of the bump foil portions 73c forming the bump foil 73 are inserted. The fixed end 73d of the bump foil portion 73c is not inserted into the fourth slit 18d.

[0059] In the circumferential direction B, among two adjacent bump foil portions 73c, the fixed end 73d of one bump foil portion 73c and the free end 73e of the other bump foil portion 73c are adjacent to each other while being separated in the circumferential direction B.

[0060] A gap 83 is formed between the fixed end 73d of one bump foil portion 73c and the free end 73e of the other bump foil portion 73c among two adjacent bump foil portions 73c in the circumferential direction B. The gap 83 is formed regardless of the extension of the plurality of bump foil portions 73c. The gap 83 is a gap that penetrates the bump foil 73 in the radial direction Y, which is the direction from the top foil 72 toward the bearing housing portion 18. The gap 83 will be formed at three locations separated from each other in the circumferential direction B.

[0061] Each bump foil portion 73c is interposed between the inner peripheral surface 18g of the bearing housing portion 18 and the bump foil surface 72t of the top foil 72. Therefore, the bump foil 73 composed of a plurality of bump foil portions 73c is disposed between the inner peripheral surface 18g of the bearing housing portion 18 and the bump foil surface 72t of the top foil 72. Due to the interposition of the bump foil portion 73c, an annular gap S is formed between the inner peripheral surface 18g of the bearing housing portion 18 and the bump foil surface 72t of the top foil 72. Both ends in the axial direction X of the gap S are open at portions other than the bump foil portion 73c. The opening width W in the radial direction Y of this gap S changes according to the expansion and contraction of the bump foil portion 73c in the circumferential direction B and the eccentricity of the rotating shaft 40.

[0062] Next, the radial foil bearing 20 in a state where no load acts on the bearing surface 72s from the rotating shaft 40 will be described. As shown in FIG. 3, the state where no load acts on the bearing surface 72s from the rotating shaft 40 means a state where the rotating shaft 40 is not rotating and the entire bearing surface 72s in the circumferential direction B is in contact with the circumferential surface of the rotating shaft 40. Such a state where no load acts on the bearing surface 72s from the rotating shaft 40 is hereinafter referred to as a no-load state.

[0063] <No-load state> As shown in FIG. 3, in the no-load state, each peak portion 81 provided in each bump foil portion 73c locally contacts the bump foil surface 72t of the top foil 72. In the no-load state, the tip portion of the peak portion 81 in the protruding direction toward the top foil 72 contacts the bump foil surface 72t of the top foil 72. In the no-load state, each valley portion 82 provided in the bump foil portion 73c locally contacts the inner peripheral surface 18g of the bearing housing portion 18. In the no-load state, the tip portion of the valley portion 82 in the protruding direction toward the bearing housing portion 18 contacts the inner peripheral surface 18g of the bearing housing portion 18.

[0064] <First state> Next, the first state will be described. The first state refers to the state of the radial foil bearing 20 when the rotating shaft 40 rotates and floats from the bearing surface 72s.

[0065] As shown in FIGS. 4 and 5, in the first state, as the rotating shaft 40 rotates, the top foil 72 elastically deforms outward in the radial direction Y. As a result, an air film is formed between the peripheral surface of the rotating shaft 40 and the bearing surface 72s of the top foil 72, and thus hydrodynamic pressure is generated. Thereby, the radial foil bearing 20 rotatably supports the rotating shaft 40 in a non-contact state with respect to the top foil 72.

[0066] When the top foil 72 elastically deforms outward in the radial direction Y due to the air film between the rotating shaft 40 and the top foil 72, each peak portion 81 of the bump foil portion 73c in contact with the bump foil surface 72t of the top foil 72 is pressed by the top foil 72. As a result, the bump foil 73 elastically deforms outward in the radial direction Y together with the top foil 72. In this way, the top foil 72 is elastically supported by the bump foil 73. As the displacement of the top foil 72 outward in the radial direction Y occurs, each peak portion 81 and each valley portion 82 elastically deform. In the first state, a load acts uniformly on the entire bearing surface 72s from the rotating shaft 40 through the air film. Therefore, each peak portion 81 and each valley portion 82 elastically deform uniformly. In the first state, the opening width W in the radial direction Y in the gap S becomes narrower than the unloaded state due to the elastic deformation of the bump foil portion 73c. Let the distance between the inner peripheral surface 18g of the bearing housing portion 18 in the radial direction Y and the bump foil surface 72t be the first distance.

[0067] <Second State> Next, the second state will be described. As shown in FIGS. 6 and 7, the second state means the state of the radial foil bearing 20 in which the rotating shaft 40 approaches the inner peripheral surface 18g of the bearing housing portion 18 more than in the first state in a part in the circumferential direction B. In the second state, the state where the rotating shaft 40 approaches the bearing housing portion 18 more than in the first state means, for example, the case where the rotating shaft 40 is eccentric in the radial direction Y due to external excitation or the like, for example, the case where the rotating shaft 40 is displaced in the radial direction Y. In the bearing housing portion 18, the position where the rotating shaft 40 comes closest is defined as the approaching position P1. In the bearing housing portion 18, the side opposite to the approaching position P1 in the radial direction Y is defined as the separating position P2. The separating position P2 is the position where the rotating shaft 40 is most separated from the inner peripheral surface 18g of the bearing housing portion 18.

[0068] In the second state, at the approaching position P1, the peak portions 81 and the valley portions 82 are elastically deformed more greatly than in the first state. As a result, the contact range of the top foil 72 in the bump foil portion 73c with the bearing housing portion 18 is expanded more than in the first state. Further, along with the elastic deformation of each peak portion 81 and each valley portion 82, in the vicinity of the approaching position P1, the bump foil portion 73c is deformed so that the fixed end 73d and the free end 73e adjacent to each other in the circumferential direction B approach each other. As a result, at the approaching position P1, the bump foil surface 72t of the top foil 72 approaches the inner peripheral surface 18g of the bearing housing portion 18.

[0069] Conversely, in the second state, at the separating position P2, the peak portions 81 and the valley portions 82 are elastically deformed less than in the first state. As a result, the contact range of the top foil 72 in the bump foil portion 73c with the bearing housing portion 18 is reduced more than in the first state. Along with the elastic deformation of each peak portion 81 and each valley portion 82, in the vicinity of the separating position P2, the bump foil portion 73c is deformed so that the fixed end 73d and the free end 73e adjacent to each other in the circumferential direction B move away from each other. As a result, at the separating position P2, the bump foil surface 72t of the top foil 72 is separated from the inner peripheral surface 18g of the bearing housing portion 18.

[0070] In the second state, the opening width W in the radial direction Y at the gap S at the approaching position P1 is narrower than that in the first state. On the other hand, in the second state, the opening width W in the radial direction Y at the gap S at the separating position P2 is wider than that in the first state.

[0071] <Sealing member 100> As shown in FIG. 1, the centrifugal compressor 10 is provided at the axial end of the radial foil bearing 20 and has a sealing member 100 that suppresses the leakage of high-pressure air from each impeller chamber 13b, 14b to the motor chamber 51 through each radial foil bearing 20.

[0072] The sealing member 100 is formed by shaping a flexible metal plate material such as stainless steel. A shaft insertion hole 100a is formed in the central portion of the sealing member 100. The shaft insertion hole 100a penetrates the sealing member 100 in the axial direction X. The sealing member 100 is provided adjacent to each radial foil bearing 20 in the axial direction X. And a rotating shaft 40 is inserted through the sealing member 100.

[0073] The sealing member 100 adjacent to the radial foil bearing 20 fixed to the bearing housing portion 18 of the first plate 15 is provided on the first impeller chamber 13b side in the axial direction X with respect to the radial foil bearing 20. The sealing member 100 adjacent to the radial foil bearing 20 fixed to the bearing housing portion 18 of the motor housing 12 is provided on the second impeller chamber 14b side in the axial direction X with respect to the radial foil bearing 20. The shapes of the two sealing members 100 are the same.

[0074] As shown in FIG. 4, the sealing member 100 includes an annular plate portion 101, three locking portions 102, and a top foil contact portion 103. The annular plate portion 101 is in the form of a thin plate. The annular plate portion 101 is a portion on the outer peripheral side in the radial direction Y with respect to the locking surface 102a of the locking portion 102 in the seal member 100. Note that the locking surface 102a of the locking portion 102 will be described later. The outer diameter of the seal member 100 at the annular plate portion 101 is also the outer diameter of the seal member 100. The outer diameter of the annular plate portion 101 is smaller than the outer diameter of the bearing housing portion 18. Here, in the bearing housing portion 18, among the inner surfaces of the first to fourth slits 18a to 18d, the inner surface located on the outermost peripheral side in the radial direction Y of the bearing housing portion 18 is defined as the inner bottom surface 181. The inner bottom surface 181 of the bearing housing portion 18 provided in the motor housing 12 is located on the inner side in the radial direction Y with respect to the inner peripheral surface of the second bearing recess 12c. Also, the inner bottom surface 181 of the bearing housing portion 18 provided in the first plate 15 is located on the inner side in the radial direction Y with respect to the inner peripheral surface of the first bearing recess 15d.

[0075] A circle formed by connecting the inner bottom surfaces 181 of the first to fourth slits 18a to 18d in the circumferential direction B of the bearing housing portion 18 is defined as the first virtual circle C1. The diameter of the first virtual circle C1 is smaller than the outer diameter of the annular plate portion 101. Therefore, in the no-load state, the annular plate portion 101 covers the openings on the first end surface 18A side in the first to fourth slits 18a to 18d.

[0076] Also, the dimension in the radial direction Y from the inner peripheral surface 18g to the inner bottom surface 181 of the bearing housing portion 18 is defined as the depth D of the first to fourth slits 18a to 18d. The dimension of the annular plate portion 101 in the radial direction Y is larger than the sum of the opening width W of the gap S at the separation position P2 and the depth D when the rotation shaft 40 approaches any one of the first to fourth slits 18a to 18d and enters the second state.

[0077] Therefore, as shown in FIG. 6, the annular plate portion 101 is large enough to cover the outer peripheral positions of the first to fourth slits 18a to 18d along the radial direction Y of the bearing housing portion 18. Thus, the annular plate portion 101 is large enough to cover all of the first to fourth slits 18a to 18d regardless of whether it is in the no-load state, the first state, or the second state. And the annular plate portion 101 covers from the radial outer periphery of the top foil 72 to the radial outer peripheral position from the radial inner peripheral position of the bearing housing portion 18. That is, the annular plate portion 101 covers the gap S across the entire circumferential direction B regardless of whether it is in the no-load state, the first state, or the second state.

[0078] As shown in FIGS. 4 and 5, each locking portion 102 is a ridge protruding in the axial direction X from the annular plate portion 101 toward the radial foil bearing 20. Each locking portion 102 is formed by raising a part of the inner peripheral portion of the metal plate material. The seal member 100 is formed with a groove 103a formed by raising the locking portion 102 from the metal plate material. The three locking portions 102 are formed at equal intervals in the circumferential direction B. Therefore, the three locking portions 102 are formed as a plurality of locking pieces spaced apart in the circumferential direction of the annular plate portion 101.

[0079] The plate thickness of each locking portion 102 matches the plate thickness of the metal plate material forming the seal member 100. Each locking portion 102 includes a locking surface 102a on the inner peripheral side of the seal member 100 among both surfaces in the plate thickness direction of the locking portion 102. Let the circle connecting the locking surface 102a in the circumferential direction B be the second virtual circle C2. Although the second virtual circle C2 is shown in FIG. 4, since the second virtual circle C2 coincides with the bump foil surface 72t of the top foil 72, the second virtual circle C2 is shown by a broken line in FIG. 4. The diameter of this second virtual circle C2 is larger than the sum of the value of the diameter of the rotating shaft 40 and twice the value of the plate thickness of the top foil 72. And the locking surface 102a of each of the three locking portions 102 is locked to the bump foil surface 72t as the radial outer periphery of the top foil 72.

[0080] As shown in FIG. 3, each locking portion 102 is arranged by being inserted into a gap 83 between a fixed end 73d and a release end 73e adjacent to each other in the circumferential direction B, and is locked to a bump foil surface 72t located in the gap 83.

[0081] As shown in FIGS. 4 and 5, the top foil contact portion 103 is provided on the inner circumferential side of a locking surface 102a of the locking portion 102 in the radial direction Y of the seal member 100. The inner diameter of the seal member 100 at the radially inner circumferential end of the top foil contact portion 103 is larger than the diameter of the rotating shaft 40. The top foil contact portion 103 has a part of the circumferential direction B divided by three grooves 103a. In the top foil contact portion 103, the dimension from the locking surface 102a of the locking portion 102 in the radial direction Y to the tip of the top foil contact portion 103 is less than the plate thickness of the top foil 72. In any of the no-load state, the first state, and the second state, when the locking surface 102a of the locking portion 102 is locked to the bump foil surface 72t, the top foil contact portion 103 is arranged at a position where it can contact the axial end surface 72c of the top foil 72. The top foil contact portion 103 contacts the axial end surface 72c of the top foil 72, and the top foil contact portion 103 extends between the radially outer circumferential position and the radially inner circumferential position of the top foil 72.

[0082] [Operation of the First Embodiment] The operation of the first embodiment will be described. During the operation of the centrifugal compressor 10, the first impeller 34 rotates with the rotation of the rotating shaft 40, and air is taken into the first impeller chamber 13b from the suction port 13a. Then, after the air is compressed in the first diffuser flow path 13d, it flows into the discharge chamber 13c and the first high-pressure passage 90.

[0083] The air discharged from the discharge chamber 13c is supplied to a fuel cell stack (not shown). The exhaust gas of the fuel cell stack is inhaled into the intake chamber 14c. The exhaust gas of the fuel cell stack inhaled into the intake chamber 14c is discharged into the second impeller chamber 14b through the second diffuser flow path 14d. The second impeller 35 rotates due to the exhaust gas of the fuel cell stack discharged into the second impeller chamber 14b. The rotation of the second impeller 35 due to the exhaust gas of the fuel cell stack assists the rotation of the rotating shaft 40. The exhaust gas of the fuel cell stack discharged into the intake chamber 14c is discharged to the outside from the discharge port 14a.

[0084] During the operation of the centrifugal compressor 10, the radial foil bearing 20 supports the rotating shaft 40 in a non-contact state in the first state. The seal member 100 is urged toward the radial foil bearing 20 in the axial direction X under the high pressure of the first high-pressure passage 90 and the second high-pressure passage 91. As shown in FIG. 5, the annular plate portion 101 of the seal member 100 is pressed against the first end face 18A of the bearing housing portion 18 by this urging force. Thereby, the annular plate portion 101 seals between each of the high-pressure passages 90, 91 and the radial foil bearing 20, and the first to fourth slits 18a to 18d and the gap S formed in the bearing housing portion 18.

[0085] Also, due to the urging force, the top foil contact portion 103 is also urged toward the radial foil bearing 20. The top foil contact portion 103 contacts the axial end face 72c of the top foil 72 to seal between the locking surface 102a of the locking portion 102 and the bump foil surface 72t.

[0086] Also, as shown in FIGS. 6 and 7, in the operating state, when the centrifugal compressor 10 receives an external force due to external vibration or the like, the rotating shaft 40 may be eccentric and enter the second state. When the rotating shaft 40 is displaced in the radial direction Y, the top foil 72 also displaces following the rotating shaft 40. At this time, since the locking portion 102 is locked to the top foil 72, the seal member 100 also displaces in the same manner as the rotating shaft 40. By displacing the seal member 100 in the same manner as the rotating shaft 40, the sealing condition by the annular plate portion 101 and the top foil contact portion 103 can be maintained.

[0087] [Effects of the First Embodiment] The effects of the first embodiment will be described. (1-1) The seal member 100 is locked to the bump foil surface 72t of the top foil 72 by the locking portion 102. When the centrifugal compressor 10 receives an external force due to external vibration or the like, the seal member 100 displaces following the displacement of the rotating shaft 40 in the radial direction Y. Therefore, the annular plate portion 101 can maintain the state of covering the gap S. As a result, the centrifugal compressor 10 can suppress the leakage of high-pressure air from the first impeller chamber 13b to the motor chamber 51 via the first high-pressure passage 90 and the radial foil bearing 20, and the leakage of high-pressure air from the second impeller chamber 14b to the motor chamber 51 via the second high-pressure passage 91 and the radial foil bearing 20 by the seal member 100. As a result, the centrifugal compressor 10 does not need to be provided with a complicated configuration such as a labyrinth seal in the housing 11 in order to suppress the leakage of high-pressure air from each impeller chamber 13b, 14b to the motor chamber 51. In addition, since the leakage of high-pressure and high-temperature air can be suppressed, heat damage to the motor 39 can be reduced, and an increase in power consumption due to a decrease in the output of the motor 39 caused by heat damage can be suppressed.

[0088] (1-2) The seal member 100 is formed separately from the radial foil bearing 20. As a result, for example, unlike the case where the top foil 72 is bent to integrally form the seal member, there is no risk of the shape of the top foil 72 changing when providing the seal member. Consequently, in the radial foil bearing 20, it is possible to suppress the influence on rotatably supporting the rotating shaft 40 in a non-contact state.

[0089] (1-3) Each of the three locking portions 102 is inserted into the gap 83 between the bump foil portions 73c adjacent to each other in the circumferential direction B. Thereby, the locking portion 102 can be locked to the top foil 72 without changing the axial length X of the three bump foil portions 73c. That is, by utilizing the gap 83 between the fixed end 73d and the release end 73e adjacent to each other in the circumferential direction B, the locking portion 102 can be locked to the bump foil surface 72t of the top foil 72. For this reason, unlike the case where the locking portion 102 is formed in a cylindrical shape extending over the entire circumferential direction B of the bearing housing portion 18, the centrifugal compressor 10 can lock the locking portion 102 to the bump foil surface 72t of the top foil 72 without requiring a configuration for avoiding interference between the locking portion 102 and the bump foil 73. Also, the locking portion 102 can be locked to the bump foil surface 72t of the top foil 72 without interfering the seal member 100 with the top foil fixed end 72a and the fixed end 73d in the bump foil portion 73c.

[0090] (1-4) The locking portion 102 is three locking pieces formed separately in the circumferential direction of the annular plate portion 101. For this reason, it becomes easy to create the locking portion 102 in the seal member 100. (1-5) The top foil contact portion 103 of the seal member 100 is disposed to face the axial end face 72c of the top foil 72 in a state of being located on the inner circumference in the radial direction Y with respect to the bump foil surface 72t of the top foil 72. For this reason, the top foil contact portion 103 can suppress the leakage of the compressed air along the bump foil surface 72t of the top foil 72. Thereby, the leakage of the high-pressure air from each impeller chamber 13b, 14b to the motor chamber 51 can be further suppressed.

[0091] (1-6) The annular plate portion 101 is large enough to cover all of the first to fourth slits 18a to 18d regardless of whether it is in the no-load state, the first state, or the second state. For this reason, even in the radial foil bearing 20 in which the first to fourth slits 18a to 18d are provided in the bearing housing portion 18 in order to suppress the circumferential movement B of the top foil 72 and the bump foil portion 73c, the leakage of the high-pressure air from each impeller chamber 13b, 14b to the motor chamber 51 through the first to fourth slits 18a to 18d can be suppressed by the annular plate portion 101.

[0092] [Second Embodiment] Hereinafter, a second embodiment in which a centrifugal compressor is embodied will be described with reference to FIGS. 8 and 9. The main differences from the first embodiment are the number of slits in the bearing housing portion, the shape of the bump foil, the shape of the locking portion, and the presence or absence of the top foil contact portion. For this reason, detailed description of the same configuration as that of the first embodiment will be omitted.

[0093] As shown in FIG. 8, the radial foil bearing 20 of the second embodiment has a top foil 72 and a bump foil 110. Further, the centrifugal compressor 10 has a seal member 111.

[0094] On the inner peripheral surface 18g of the bearing housing portion 18, two slits 114 are formed. The two slits 114 are provided over the entire length of the bearing housing portion 18 in the axial direction X. Further, the two slits 114 are provided so as to be adjacent to each other in the circumferential direction B. The two slits 114 open toward the first impeller chamber 13b or the second impeller chamber 14b at the first end face 18A of the bearing housing portion 18. Also, the two slits 114 open toward the motor chamber 51 at the second end face 18B of the bearing housing portion 18.

[0095] The bump foil 110 is not divided like the three bump foil portions 73c of the first embodiment. The bump foil 110 includes one fixed end 110d and one free end 110e. The bump foil 110 is annular and interrupted only between the fixed end 110d and the free end 110e. The length of the bump foil 110 in the axial direction X is shorter than the length of the top foil 72 in the axial direction X. Let the difference between the length of the bump foil 110 in the axial direction X and the length of the top foil 72 in the axial direction X be "difference L".

[0096] One top foil fixed end 72a is inserted into one slit 114, and the other top foil fixed end 72a is inserted into the other slit 114. Also, the fixed end 110d of the bump foil 110 is inserted into one of the slits 114.

[0097] The seal member 111 has an annular plate portion 101 and a locking portion 112. The locking portion 112 is formed by bending the inner peripheral portion of an annular metal plate material. Specifically, the locking portion 112 is formed by drawing a metal plate material. The locking portion 112 is cylindrical. The locking portion 112 projects in the plate thickness direction of the annular plate portion 101, that is, in the axial direction X. The length of the locking portion 112 in the axial direction X is formed to be shorter than the difference L.

[0098] The inner diameter of the locking portion 112 is larger than the sum of the value of the diameter of the rotating shaft 40 and twice the value of the plate thickness of the top foil 72. The locking portion 112 has a pair of fitting grooves 113 formed in a part of the circumferential direction B. One of the fitting grooves 113 has the one top foil fixed end 72a and the fixed end 110d of the bump foil 110 fitted therein, and the other fitting groove 113 has the other top foil fixed end 72a fitted therein. And the locking portion 112 extends between the end face in the axial direction X of the top foil 72 and the end face in the axial direction X of the bump foil 110 and is locked to the bump foil surface 72t of the top foil 72.

[0099] [Effects of the Second Embodiment] The effects of the second embodiment will be described. In the second embodiment, it has the same effects as (1-1), (1-2), and (1-6) of the first embodiment and the following effects.

[0100] (2-1) The locking portion 112 of the seal member 111 is cylindrical, and the locking portion 112 is formed with fitting grooves 113 for avoiding interference with the top foil fixed end 72a. For example, compared with the case where the locking portions 112 are arranged at intervals in the circumferential direction B, the locking area of the locking portion 112 with respect to the bump foil surface 72t of the top foil 72 can be increased. Therefore, the seal member 111 is more likely to follow the top foil 72. Also, the fitting grooves 113 can avoid interference between the locking portion 112 and the top foil fixed end 72a.

[0101] [Modification Example] Note that the above embodiments can be implemented with the following modifications. The above embodiments and the following modification examples can be implemented in combination with each other within a technically non-conflicting range.

[0102] ○ As shown in Fig. 10, in the first and second embodiments, the bearing housing portion 18 may be formed of a cylindrical holding portion 182 and a bearing housing forming member 183 fixed to the inner peripheral surface of the holding portion 182. The bearing housing forming member 183 is cylindrical. The inner peripheral surface of the bearing housing forming member 183 forms the inner peripheral surface 18g of the bearing housing portion 18. In the first embodiment, first to fourth slits 18a to 18d are formed in the inner peripheral surface of the bearing housing forming member 183, and in the second embodiment, a slit 114 is formed in the inner peripheral surface of the bearing housing forming member 183. Also, a first end face 18A is formed by one end face in the axial direction of the bearing housing forming member 183, and a second end face 18B is formed by the other end face in the axial direction of the bearing housing forming member 183.

[0103] ○ In the second embodiment, the seal member 111 may have a top foil contact portion on the inner peripheral portion rather than the locking portion 112. ○ In the first embodiment, the seal member 100 may not have the top foil contact portion 103.

[0104] ○ In the first embodiment, the number of the locking portions 102 may be two or four or more. That is, the number of the locking portions 102 may be appropriately changed, or the dimensions in the circumferential direction B of each locking portion 102 may be adjusted according to the number of the locking portions 102.

[0105] ○ In the first embodiment, the length of the bump foil portion 73c in the axial direction X may be shorter than the length of the top foil 72 in the axial direction X. In this case, the locking portion 102 may not be inserted into the gap 83 between the adjacent bump foil portions 73c in the circumferential direction B, and the position where the locking portion 102 locks is arbitrary.

[0106] ○ In the first embodiment, the annular plate portion 101 may not be sized to cover the first to fourth slits 18a to 18d, and in the second embodiment, the annular plate portion 101 may not be sized to cover the slit 114.

[0107] ○ In the first embodiment, the bearing housing portion 18 may not have the first to fourth slits 18a to 18d formed therein. In this case, the top foil 72 does not have the top foil fixed end 72a, and the bump foil portion 73c does not have the fixed end 73d. Also, in the second embodiment, the bearing housing portion 18 may not have the slit 114 formed therein. In this case, the top foil 72 does not have the top foil fixed end 72a, and the bump foil 110 does not have the fixed end 110d. And each of the top foil 72, the bump foil portion 73c, and the bump foil 110 is fixed to the inner peripheral surface 18g of the bearing housing portion 18 by welding or the like. In this case, the outer diameters of the seal members 100 and 111 are smaller than those in the embodiment.

[0108] ○ The centrifugal compressor 10 may be configured not to include, for example, the second impeller 35. ○ The fluid compressed by the first impeller 34 and the second impeller 35 is not limited to air. As the fluid, for example, a refrigerant or a fluorocarbon in which a gaseous state and a liquid state are mixed may be used. Therefore, the fluid to be compressed by the centrifugal compressor 10 is arbitrary. For example, the centrifugal compressor 10 may be used in an air conditioner. In this case, the centrifugal compressor 10 may compress a refrigerant. The object to which the centrifugal compressor 10 is mounted is not limited to a vehicle and is arbitrary.

Description of Reference Numerals

[0109] 10... centrifugal compressor, 11... housing, 13b... first impeller chamber as impeller chamber, 14b... second impeller chamber, 18... bearing housing portion, 18a... first slit, 18b... second slit, 18c... third slit, 18d... fourth slit, 20... radial foil bearing, 34... first impeller as impeller, 35... second impeller, 39... motor, 40... rotating shaft, 51... motor chamber, 72... top foil, 72c... end face in axial direction, 73, 110... bump foil, 73c... plurality of bump foil portions, 73d... fixed end, 73e... free end, 100, 111... seal member, 101... annular plate portion, 102, 112... locking portion, 103... top foil abutting portion, 113... fitting groove, 114... slit.

Claims

1. A rotating shaft driven by a motor, an impeller that compresses fluid by rotating integrally with the rotating shaft, a housing that houses the rotating shaft and has a motor chamber for housing the motor and an impeller chamber for housing the impeller, a radial foil bearing disposed inside the housing and rotatably supporting the rotating shaft between the impeller chamber and the motor chamber in the axial direction of the rotating shaft, a seal member provided at an axial end of the radial foil bearing to suppress leakage of fluid from the impeller chamber to the motor chamber, and the housing has a bearing housing portion to which the radial foil bearing is fixed, the radial foil bearing has a top foil disposed between the bearing housing portion and the rotating shaft, and a bump foil disposed between the bearing housing portion and the top foil and elastically supporting the top foil, the seal member has an annular plate portion through which the rotating shaft is inserted and that covers from a radially outer periphery of the top foil to a radially outer periphery position from a radially inner periphery position of the bearing housing portion, and a locking portion that protrudes in the axial direction of the rotating shaft from the annular plate portion toward the radial foil bearing and is locked to the radially outer periphery of the top foil. A centrifugal compressor characterized by this.

2. The bearing housing portion opens toward the impeller chamber and the motor chamber and has a slit into which a fixed end of at least one of the top foil and the bump foil is inserted, and the annular plate portion covers an outer peripheral position of the slit along the radial direction of the bearing housing portion. The centrifugal compressor according to claim 1, characterized by this.

3. The centrifugal compressor according to claim 1 or claim 2, characterized in that the locking portion is formed as a plurality of locking pieces provided at intervals in the circumferential direction of the annular plate portion.

4. The bump foil has a plurality of bump foil portions arranged in the circumferential direction of the bearing housing portion. Each of the plurality of bump foil portions has a fixed end fixed to the bearing housing portion at one end in the circumferential direction of the bump foil portion, and a free end at the other end in the circumferential direction of the bump foil portion. The centrifugal compressor according to claim 3, wherein the locking portion is inserted between the fixed end and the free end of the bump foil portions adjacent to each other in the circumferential direction.

5. The seal member includes a top foil contact portion that contacts the axial end surface of the top foil on the inner circumferential side of the locking portion in the radial direction of the seal member. The centrifugal compressor according to claim 1 or claim 2, wherein the top foil contact portion extends between a radially outer peripheral position and a radially inner peripheral position of the top foil.

6. The locking portion is cylindrical, and a fitting groove into which a fixed end of the top foil to the bearing housing portion is fitted is formed in the locking portion. The centrifugal compressor according to claim 1, characterized in that.

7. The length of the top foil in the axial direction is longer than the length of the bump foil in the axial direction. The centrifugal compressor according to claim 6, wherein the locking portion extends between the end surface of the bump foil in the axial direction and the end surface of the top foil in the axial direction and is locked to the radially outer periphery of the top foil.

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