Centrifugal compressor

Abstract

A centrifugal compressor (CC) is provided with: an intake passage (130) connected to an intake port; a compressor impeller (9) disposed in the intake flow path (130); a movable member that is a first movable member (210) that is provided on the intake port side of the compressor impeller (9) in the intake flow path (130) and that can move to a protruding position that protrudes into the intake flow path (130) and a retracted position that retracts from the intake flow path (130); a first end (216) that is an end on the compressor impeller (9) side of the inner peripheral surface (S3) of the movable member; a second end (217) that is an end on the intake port side of the inner peripheral surface (S3) of the movable member; and an extension section (218) that is provided between the first end section (216) and the second end section (217) and that extends in a direction corresponding to the direction of the rotation axis of the compressor impeller (9).

Description

Technical Field

[0001] The present disclosure relates to a centrifugal compressor. This application claims the benefit of priority based on Japanese Patent Application No. 2022-143038 filed on September 8, 2022, the contents of which are incorporated herein by reference. Background Art

[0002] The centrifugal compressor includes a compressor housing having an intake air path formed therein. A compressor impeller is disposed in the intake air path. When the flow rate of air flowing into the compressor impeller decreases, the air compressed by the compressor impeller flows back in the intake air path, causing a phenomenon called surge.

[0003] Patent document 1 discloses a centrifugal compressor in which a throttling mechanism is provided on a compressor housing. The throttling mechanism is arranged on the upstream side of the intake air relative to the compressor impeller. The throttling mechanism has a movable component. The movable component is configured to be movable between a protruding position protruding into the intake air path and a retreating position retreating from the intake air path. The throttling mechanism reduces the flow path cross-sectional area of ​​the intake air path by causing the movable component to protrude into the intake air path. When the movable component protrudes into the intake air path, the air flowing back in the intake air path is blocked by the movable component. Surge is suppressed by blocking the air flowing back in the intake air path.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: European Patent Application Publication No. 3530954 Summary of the invention

[0007] Problems to be solved by the invention

[0008] In a centrifugal compressor provided with a movable member to suppress surge, when a strong backflow of air occurs in the intake air passage, the movable member may not be able to sufficiently block the backflow of air. In this case, the efficiency of the centrifugal compressor decreases.

[0009] An object of the present disclosure is to provide a centrifugal compressor capable of suppressing a decrease in efficiency of the centrifugal compressor.

[0010] Solutions to Solve Problems

[0011] In order to solve the above-mentioned problems, the centrifugal compressor disclosed in the present invention comprises: an intake air flow path, which is connected to the intake port; a compressor impeller, which is arranged in the intake air flow path; a movable part, which is arranged in the intake air flow path at a position closer to the intake port side than the compressor impeller, and can be moved to a protruding position protruding into the intake air flow path and a retreating position retreating from the intake air flow path; a first end, which is the end of the compressor impeller side of the inner circumferential surface of the movable part; a second end, which is the end of the intake port side of the inner circumferential surface of the movable part; and an extension part, which is arranged between the first end and the second end and extends in a direction corresponding to the direction of the rotation axis of the compressor impeller.

[0012] The radius of curvature of the second end may also be larger than the radius of curvature of the first end.

[0013] The radius of curvature of the second end portion may be larger than the thickness of the movable member in the rotation axis direction.

[0014] A rounded portion may be formed between the second end portion and a surface of the movable member that faces the air inlet side.

[0015] The radial distance between the inner peripheral end of the surface of the movable member facing the air inlet side and the extending portion may be 80% or less of the thickness of the movable member in the rotation axis direction.

[0016] The radial distance between the inner peripheral end of the surface of the movable member facing the air inlet side and the extending portion may be equal to or greater than 20% of the thickness of the movable member in the rotation axis direction.

[0017] Effects of the Invention

[0018] According to the present disclosure, it is possible to suppress a decrease in the efficiency of the centrifugal compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic cross-sectional view of a supercharger according to an embodiment of the present disclosure.

[0020] Figure 2 yes Figure 1 Extraction diagram of the dotted part of .

[0021] Figure 3 This is an exploded perspective view of the components that make up the link mechanism.

[0022] Figure 4 yes Figure 2 Sectional view along line IV-IV.

[0023] Figure 5 This is the first diagram for explaining the operation of the link mechanism.

[0024] Figure 6 This is a second diagram for explaining the operation of the link mechanism.

[0025] Figure 7 This is the third diagram for explaining the operation of the link mechanism.

[0026] Figure 8 It is a schematic cross-sectional view showing the shape of the movable member in detail.

[0027] Fig. 9 yes Figure 8 Extraction diagram of the dotted part of .

[0028] Fig.10 It is a schematic cross-sectional view showing the shape of a movable member according to a modified example. DETAILED DESCRIPTION

[0029] Hereinafter, the embodiments of the present disclosure will be described with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values ​​shown in the embodiments are merely examples for easy understanding and do not limit the present disclosure unless otherwise specified. In addition, in this specification and the accompanying drawings, for elements having substantially the same function and structure, repeated descriptions are omitted by marking the same figure numbers, and elements that are not directly related to the present disclosure are omitted from the drawings.

[0030] Figure 1 1 is a schematic cross-sectional view of the supercharger TC. Figure 1 The arrow L direction shown is explained as the left side of the supercharger TC. Figure 1 The arrow R direction shown is described as the right side of the supercharger TC. The compressor housing 100 side described later in the supercharger TC functions as a centrifugal compressor CC. In the following, a case where the centrifugal compressor CC is driven by the turbine impeller 8 described later is described. However, this is not limited to this, and the centrifugal compressor CC can be driven by an engine not shown in the figure, or by an electric motor not shown in the figure. In this way, the centrifugal compressor CC can be assembled in a device other than the supercharger TC, or it can be a single body.

[0031] like Figure 1 As shown, the supercharger TC includes a supercharger body 1. The supercharger body 1 includes a bearing housing 2, a turbine housing 4, a compressor housing 100, and a connecting rod mechanism 200. The details of the connecting rod mechanism 200 will be described later. The turbine housing 4 is connected to the left side of the bearing housing 2 by a fastening bolt 3. The compressor housing 100 is connected to the right side of the bearing housing 2 by a fastening bolt 5.

[0032] A receiving hole 2a is formed in the bearing housing 2. The receiving hole 2a passes through the supercharger TC in the left-right direction. A bearing 6 is arranged in the receiving hole 2a. The bearing 6 is, for example, a fully floating bearing. However, the bearing 6 may also be another radial bearing such as a semi-floating bearing or a rolling bearing. A portion of the shaft 7 is arranged in the receiving hole 2a. The shaft 7 is rotatably supported by the bearing 6. A turbine impeller 8 is provided at the left end of the shaft 7. The turbine impeller 8 is rotatably accommodated in the turbine housing 4. A compressor impeller 9 is provided at the right end of the shaft 7. The compressor impeller 9 is rotatably accommodated in the compressor housing 100.

[0033] An air inlet 10 is formed in the compressor housing 100. The air inlet 10 opens on the right side of the supercharger TC. The air inlet 10 is connected to an air filter (not shown). A diffusion flow path 11 is formed between the bearing housing 2 and the compressor housing 100. The diffusion flow path 11 increases the pressure of the air. The diffusion flow path 11 is formed in an annular shape from the inner side of the radial direction (hereinafter referred to as the radial direction) of the compressor impeller 9 toward the outer side. The diffusion flow path 11 is connected to the air inlet 10 via the compressor impeller 9 on the inner side of the radial direction.

[0034] In addition, a compressor scroll flow path 12 is formed in the compressor housing 100. The compressor scroll flow path 12 is formed in an annular shape. The compressor scroll flow path 12 is located, for example, at a position radially outside the compressor impeller 9. The compressor scroll flow path 12 is connected to an air intake port and a diffuser flow path 11 of an engine (not shown). When the compressor impeller 9 rotates, air is sucked into the compressor housing 100 from the air intake port 10. The sucked air is pressurized and accelerated during the process of flowing between the blades of the compressor impeller 9. The pressurized and accelerated air is pressurized in the diffuser flow path 11 and the compressor scroll flow path 12. The pressurized air flows out from an exhaust port (not shown) and is guided to the air intake port of the engine.

[0035] As described above, the supercharger TC includes the centrifugal compressor CC. The centrifugal compressor CC includes the compressor housing 100, the compressor impeller 9, and the link mechanism 200 described later.

[0036] The turbine housing 4 is provided with an exhaust port 13. The exhaust port 13 opens on the left side of the supercharger TC. The exhaust port 13 is connected to an exhaust gas purification device (not shown). The turbine housing 4 is provided with a communication flow path 14 and a turbine vortex flow path 15. The turbine vortex flow path 15 is located radially outward of the turbine impeller 8. The communication flow path 14 is located between the turbine impeller 8 and the turbine vortex flow path 15.

[0037] The turbine scroll flow path 15 is connected to a gas inlet (not shown). Exhaust gas discharged from an exhaust manifold of an engine (not shown) is guided to the gas inlet. The communication flow path 14 connects the turbine scroll flow path 15 with the exhaust port 13. The exhaust gas guided from the gas inlet to the turbine scroll flow path 15 is guided to the exhaust port 13 via the communication flow path 14 and between the blades of the turbine impeller 8. The exhaust gas rotates the turbine impeller 8 during its circulation.

[0038] The rotational force of the turbine impeller 8 is transmitted to the compressor impeller 9 via the shaft 7. As described above, the air is pressurized by the rotational force of the compressor impeller 9 and is guided to the intake port of the engine.

[0039] Figure 2 yes Figure 1 The extracted image of the dotted part of Figure 1 as well as Figure 2 As shown, the compressor housing 100 includes a first housing component 110 and a second housing component 120. Figure 2 In FIG. 1 , the first housing member 110 is located on the right side of the second housing member 120. The second housing member 120 is connected to the bearing housing 2. The first housing member 110 and the second housing member 120 are connected.

[0040] like Figure 2 As shown, the first housing member 110 is substantially cylindrical. A through hole 111 is formed in the first housing member 110. The first housing member 110 has an end surface 112 on the side close to the second housing member 120. In addition, the first housing member 110 has an end surface 113 on the side away from the second housing member 120. The air inlet 10 is formed on the end surface 113. The through hole 111 extends from the end surface 112 to the end surface 113 along the rotation axis direction of the compressor impeller 9 (hereinafter referred to as the rotation axis direction). That is, the through hole 111 penetrates the first housing member 110 in the rotation axis direction.

[0041] The through hole 111 has a parallel portion 111a and a reduced diameter portion 111b. The parallel portion 111a is located closer to the end face 113 than the reduced diameter portion 111b. The inner diameter of the parallel portion 111a is substantially constant in the rotation axis direction. The reduced diameter portion 111b is located closer to the end face 112 than the parallel portion 111a. The reduced diameter portion 111b is continuous with the parallel portion 111a. The inner diameter of the portion of the reduced diameter portion 111b that is continuous with the parallel portion 111a is substantially equal to the inner diameter of the parallel portion 111a. The inner diameter of the reduced diameter portion 111b decreases as it moves away from the parallel portion 111a.

[0042] A notch 112a is formed on the end surface 112. The notch 112a is recessed from the end surface 112 toward the end surface 113. The notch 112a is formed on the outer periphery of the end surface 112. The notch 112a is, for example, substantially annular when viewed from the rotation axis direction.

[0043] In addition, a storage chamber AC is formed in the end surface 112. The storage chamber AC is formed in the first housing member 110 at a position closer to the air inlet 10 than the leading edge LE of the blade of the compressor impeller 9. The storage chamber AC includes a storage groove 112b, a bearing hole 112d, and a storage hole 115 (see Figure 3 ).

[0044] The receiving groove 112b is formed in the end surface 112. The receiving groove 112b is located between the notch 112a and the through hole 111. The receiving groove 112b is recessed from the end surface 112 toward the end surface 113. The receiving groove 112b is, for example, substantially annular when viewed from the rotation axis direction. The receiving groove 112b communicates with the through hole 111 radially inwardly.

[0045] A bearing hole 112d is formed in the wall surface 112c on the end surface 113 side of the storage groove 112b. The bearing hole 112d extends from the wall surface 112c toward the end surface 113 side along the rotation axis direction. Two bearing holes 112d are provided separately in the rotation direction (hereinafter referred to as the rotation direction or the circumferential direction) of the compressor impeller 9. The two bearing holes 112d are arranged at positions offset by 180 degrees in the rotation direction.

[0046] A through hole 121 is formed in the second housing member 120. The second housing member 120 has an end surface 122 on a side close to the first housing member 110. In addition, the second housing member 120 has an end surface 123 on a side away from the first housing member 110. The through hole 121 extends from the end surface 122 to the end surface 123 along the rotation axis direction. That is, the through hole 121 penetrates the second housing member 120 along the rotation axis direction.

[0047] The inner diameter of the end portion on the end face 122 side of the through hole 121 is substantially equal to the inner diameter of the end portion on the end face 112 side of the through hole 111. A shroud portion 121a is formed on the inner wall of the through hole 121. The shroud portion 121a is opposed to the compressor impeller 9 from the radially outer side. The outer diameter of the compressor impeller 9 increases as it is further away from the leading edge LE of the blade of the compressor impeller 9. The inner diameter of the shroud portion 121a increases as it is further away from the end face 122.

[0048] A storage groove 122a is formed in the end surface 122. The storage groove 122a is recessed from the end surface 122 to the end surface 123 side. The storage groove 122a is, for example, roughly annular when viewed from the rotation axis direction. The first housing member 110 is inserted into the storage groove 122a. The end surface 112 of the first housing member 110 abuts against the wall surface 122b on the end surface 123 side of the storage groove 122a. At this time, a storage chamber AC is formed between the first housing member 110 (specifically, the wall surface 112c) and the second housing member 120 (specifically, the wall surface 122b).

[0049] The intake flow path 130 is formed by the through hole 111 of the first housing member 110 and the through hole 121 of the second housing member 120. That is, the intake flow path 130 is formed in the compressor housing 100. The intake flow path 130 is connected to the intake port 10 on one side and to the diffuser flow path 11 on the other side. The intake port 10 and the diffuser flow path 11 are connected via the intake flow path 130. The intake port 10 side of the intake flow path 130 is set as the upstream side of the intake air, and the diffuser flow path 11 side of the intake flow path 130 is set as the downstream side of the intake air.

[0050] The compressor impeller 9 is disposed in the intake passage 130. The cross-sectional shape of the intake passage 130 perpendicular to the rotation axis direction is, for example, a circle centered on the rotation axis of the compressor impeller 9. However, the cross-sectional shape of the intake passage 130 is not limited thereto and may be, for example, an elliptical shape.

[0051] A sealant (not shown) is disposed in the notch 112a of the first housing member 110. The sealant suppresses the flow rate of air flowing through the gap between the first housing member 110 and the second housing member 120. However, the notch 112a and the sealant are not essential components.

[0052] Figure 3 FIG. 2 is an exploded perspective view of the components constituting the link mechanism 200. Figure 3 In the figure, only the first housing part 110 of the compressor housing 100 is shown. Figure 3 As shown, the link mechanism 200 includes a first housing member 110, a first movable member 210, a second movable member 220, a connecting member 230, and a rod 240. The link mechanism 200 is disposed on the intake port 10 side (upstream side) of the compressor impeller 9 in the rotation axis direction in the intake flow path 130.

[0053] The first movable member 210 is disposed in the storage groove 112b (specifically, the storage chamber AC). Specifically, the first movable member 210 is disposed between the wall surface 112c of the storage groove 112b and the wall surface 122b of the storage groove 122a in the rotation axis direction (see Figure 2 ). The first movable member 210 is formed of, for example, a resin material. For example, the first movable member 210 is formed by injection molding.

[0054] The first movable member 210 has a facing surface S1 facing the wall surface 112c of the storage groove 112b and a facing surface S2 facing the wall surface 122b of the storage groove 122a. The first movable member 210 has a main body B1. The main body B1 includes a bent portion 211 and an arm portion 212.

[0055] The curved portion 211 extends along the circumferential direction of the compressor impeller 9. The curved portion 211 is substantially in the shape of a semicircular arc. One end face 211a and the other end face 211b in the circumferential direction of the curved portion 211 extend parallel to the radial direction and the rotation axis direction. However, the one end face 211a and the other end face 211b may also be inclined relative to the radial direction and the rotation axis direction.

[0056] An arm portion 212 is provided on one end surface 211a of the curved portion 211. The arm portion 212 extends radially outward from an outer peripheral surface 211c of the curved portion 211. The arm portion 212 extends in a direction inclined with respect to the radial direction (specifically, a direction approaching the second movable member 220).

[0057] The second movable member 220 is disposed in the storage groove 112b (specifically, the storage chamber AC). Specifically, the second movable member 220 is disposed between the wall surface 112c of the storage groove 112b and the wall surface 122b of the storage groove 122a in the rotation axis direction (see Figure 2 ). The second movable member 220 is formed of, for example, a resin material. For example, the second movable member 220 is formed by injection molding.

[0058] The second movable member 220 has a facing surface S1 facing the wall surface 112c of the storage groove 112b and a facing surface S2 facing the wall surface 122b of the storage groove 122a. The second movable member 220 has a main body B2. The main body B2 includes a bent portion 221 and an arm portion 222.

[0059] The curved portion 221 extends along the circumferential direction of the compressor impeller 9. The curved portion 221 is substantially in the shape of a semicircular arc. One end face 221a and the other end face 221b in the circumferential direction of the curved portion 221 extend parallel to the radial direction and the rotation axis direction. However, the one end face 221a and the other end face 221b may also be inclined relative to the radial direction and the rotation axis direction.

[0060] An arm portion 222 is provided on one end surface 221a of the curved portion 221. The arm portion 222 extends radially outward from an outer peripheral surface 221c of the curved portion 221. The arm portion 222 extends in a direction inclined with respect to the radial direction (specifically, a direction approaching the first movable member 210).

[0061] The curved portion 211 is opposed to the curved portion 221 across the rotation center of the compressor impeller 9. That is, the curved portion 211 is opposed to the curved portion 221 across the intake air flow path 130. One end surface 211a of the curved portion 211 is opposed to the other end surface 221b of the curved portion 221 in the circumferential direction. The other end surface 211b of the curved portion 211 is opposed to one end surface 221a of the curved portion 221 in the circumferential direction. In the first movable member 210 and the second movable member 220, as described in detail later, the curved portions 211 and 221 can move in the radial direction.

[0062] The connecting member 230 is connected to the first movable member 210 and the second movable member 220. The connecting member 230 is located at a position closer to the air inlet 10 side than the first movable member 210 and the second movable member 220. The connecting member 230 is roughly arc-shaped. In the connecting member 230, a first bearing hole 231 is formed on one end side in the circumferential direction, and a second bearing hole 232 is formed on the other end side. The first bearing hole 231 and the second bearing hole 232 are open at the end surface 233 on the side of the first movable member 210 and the second movable member 220 in the connecting member 230. The first bearing hole 231 and the second bearing hole 232 extend in the direction of the rotation axis. Here, the first bearing hole 231 and the second bearing hole 232 are composed of non-through holes. However, the first bearing hole 231 and the second bearing hole 232 can also penetrate the connecting member 230 in the direction of the rotation axis.

[0063] A rod connection portion 234 is formed between the first bearing hole 231 and the second bearing hole 232 in the connecting member 230. The rod connection portion 234 is formed on an end surface 235 of the connecting member 230 on the opposite side to the first movable member 210 and the second movable member 220. The rod connection portion 234 protrudes from the end surface 235 in the direction of the rotation axis. The rod connection portion 234 is, for example, substantially cylindrical.

[0064] The rod 240 is substantially cylindrical in shape. A flat surface portion 241 is formed at one end of the rod 240, and a connecting portion 243 is formed at the other end of the rod 240. The flat surface portion 241 extends in a plane direction substantially perpendicular to the direction of the rotation axis. A bearing hole 242 is formed in the flat surface portion 241. The bearing hole 242 extends in the direction of the rotation axis. The connecting portion 243 has a connecting hole 243a. The actuator 250 (see Figures 5 to 7 The bearing hole 242 may be, for example, a long hole whose length in a direction perpendicular to the rotation axis direction and the axial direction of the rod 240 is longer than the length in the axial direction of the rod 240 .

[0065] In the rod 240, a rod large diameter portion 244 and two rod small diameter portions 245 are formed between the plane portion 241 and the connecting portion 243. The rod large diameter portion 244 is arranged between the two rod small diameter portions 245. The rod small diameter portion 245 on the plane portion 241 side of the two rod small diameter portions 245 connects the rod large diameter portion 244 and the plane portion 241. The rod small diameter portion 245 on the connecting portion 243 side of the two rod small diameter portions 245 connects the rod large diameter portion 244 and the connecting portion 243. The outer diameter of the rod large diameter portion 244 is larger than the outer diameters of the two rod small diameter portions 245.

[0066] The first housing member 110 has an insertion hole 114 formed therein. One end 114a of the insertion hole 114 is open to the outside of the first housing member 110. For example, the insertion hole 114 extends in a plane direction perpendicular to the rotation axis direction. The insertion hole 114 is located radially outward from the through hole 111. That is, the insertion hole 114 is located radially outward from the intake air path 130. The flat surface portion 241 side of the rod 240 is inserted into the insertion hole 114. The rod large diameter portion 244 is guided by the inner wall surface of the insertion hole 114. The movement of the rod 240 in directions other than the central axis direction of the insertion hole 114 is restricted.

[0067] A storage hole 115 is formed in the first housing member 110. The storage hole 115 opens at the wall surface 112c of the storage groove 112b. The storage hole 115 is recessed from the wall surface 112c toward the air inlet 10 side. The storage hole 115 is located on a side farther from the air inlet 10 than the insertion hole 114. The storage hole 115 is substantially arc-shaped when viewed from the rotation axis direction. The storage hole 115 extends longer than the connecting member 230 in the circumferential direction. The storage hole 115 is separated from the bearing hole 112d in the circumferential direction.

[0068] A communication hole 116 is formed in the first housing member 110. The communication hole 116 connects the insertion hole 114 and the storage hole 115. The communication hole 116 is formed in a substantially middle portion of the storage hole 115 in the circumferential direction. The communication hole 116 is, for example, a long hole extending substantially parallel to the extending direction of the insertion hole 114. The width of the communication hole 116 in the long side direction (specifically, the extending direction) is larger than the width of the communication hole 116 in the short side direction (specifically, the direction perpendicular to the extending direction). The width of the communication hole 116 in the short side direction is larger than the outer diameter of the rod connection portion 234 of the connection member 230.

[0069] The connecting member 230 is stored in the storage hole 115. In this way, the first movable member 210, the second movable member 220, and the connecting member 230 are arranged in the storage chamber AC formed in the first housing member 110. The circumferential length of the storage hole 115 is longer than the circumferential length of the connecting member 230. The radial width of the storage hole 115 is also larger than the radial width of the connecting member 230. Therefore, inside the storage hole 115, the connecting member 230 is allowed to move in the plane direction perpendicular to the rotation axis direction.

[0070] The rod connection part 234 is inserted into the insertion hole 114 from the communication hole 116. The plane part 241 of the rod 240 is inserted into the insertion hole 114. The bearing hole 242 of the plane part 241 faces the communication hole 116. The rod connection part 234 is inserted into and connected to the bearing hole 242. The rod connection part 234 is axially supported by the bearing hole 242.

[0071] Figure 4 yes Figure 2 IV-IV line cross-sectional view. Figure 4 As shown by the dashed line, the first movable member 210 includes a connecting shaft 213 and a rotating shaft 214. The connecting shaft 213 and the rotating shaft 214 extend from a facing surface S1 (see FIG. 1 ) of the first movable member 210 that faces the wall surface 112c. Figure 2 ) protrudes toward the rotation axis. Figure 4 In the figure, the connecting shaft portion 213 and the rotating shaft portion 214 extend to the back side of the paper. The rotating shaft portion 214 extends parallel to the connecting shaft portion 213. The connecting shaft portion 213 and the rotating shaft portion 214 are substantially cylindrical.

[0072] The outer diameter of the connecting shaft portion 213 is smaller than the inner diameter of the first bearing hole 231 of the connecting member 230. The connecting shaft portion 213 is inserted through the first bearing hole 231. The connecting shaft portion 213 is rotatably supported by the first bearing hole 231. The outer diameter of the rotating shaft portion 214 is smaller than the inner diameter of the bearing hole 112d of the first housing member 110. The rotating shaft portion 214 is inserted through the bearing hole 112d on the vertical upper side (i.e., the side close to the rod 240) of the two bearing holes 112d. The rotating shaft portion 214 is rotatably supported by the bearing hole 112d.

[0073] The second movable member 220 includes a connecting shaft 223 and a rotating shaft 224. The connecting shaft 223 and the rotating shaft 224 extend from a surface S1 (see FIG. 1 ) of the second movable member 220 that faces the wall surface 112c. Figure 2 ) protrudes along the direction of the rotation axis. Figure 4 In the figure, the connecting shaft portion 223 and the rotating shaft portion 224 extend to the back side of the paper. The rotating shaft portion 224 extends parallel to the connecting shaft portion 223. The connecting shaft portion 223 and the rotating shaft portion 224 are substantially cylindrical.

[0074] The outer diameter of the connecting shaft portion 223 is smaller than the inner diameter of the second bearing hole 232 of the connecting member 230. The connecting shaft portion 223 is inserted through the second bearing hole 232. The connecting shaft portion 223 is rotatably supported by the second bearing hole 232. The outer diameter of the rotating shaft portion 224 is smaller than the inner diameter of the bearing hole 112d of the first housing member 110. The rotating shaft portion 224 is inserted through the bearing hole 112d on the vertically lower side (i.e., the side away from the rod 240) of the two bearing holes 112d. The rotating shaft portion 224 is rotatably supported by the bearing hole 112d.

[0075] As described above, the link mechanism 200 is a four-link mechanism. The four links are the first movable member 210, the second movable member 220, the first housing member 110, and the connecting member 230. The link mechanism 200 is a four-link mechanism, so it is a limited linkage, has one degree of freedom, and is easy to control.

[0076] Figure 5is a first diagram for explaining the operation of the link mechanism 200. Figure 5 , Figure 6 as well as Figure 7 , a diagram showing the link mechanism 200 viewed from the air intake port 10 side. Figure 5 As shown, the end of the driving shaft 251 of the actuator 250 is connected to the connecting portion 243 of the rod 240 .

[0077] The actuator 250 is an electric actuator driven by electricity. The actuator 250 is, for example, an electric cylinder having a motor not shown. In this case, the rotational power of the motor is converted into power in the forward direction and transmitted to the drive shaft 251. As a result, the drive shaft 251 moves in the axial direction. When the rotational direction of the motor is switched, the moving direction of the drive shaft 251 is switched.

[0078] exist Figure 5 In the configuration shown, the first movable member 210 and the second movable member 220 abut against each other. Figure 2 as well as Figure 4 As shown, the radially inner portion of the first movable member 210, namely the protrusion 215, protrudes into the intake air path 130. The radially inner portion of the second movable member 220, namely the protrusion 225, protrudes into the intake air path 130. Figure 5 The positions of the first movable member 210 and the second movable member 220 in the state shown in FIG. 1 are referred to as protruding positions. In the protruding positions, the first movable member 210 and the second movable member 220 protrude into the intake air path 130.

[0079] like Figure 5 As shown, at the protruding position, the circumferential ends 215a and 215b of the protruding portion 215 abut against the circumferential ends 225a and 225b of the protruding portion 225. The protruding portion 215 and the protruding portion 225 form an annular hole 260. The inner diameter of the annular hole 260 is smaller than the inner diameter of the position where the protruding portions 215 and 225 protrude in the intake air flow path 130. The inner diameter of the annular hole 260 is smaller than the inner diameter of any position of the intake air flow path 130, for example.

[0080] Figure 6 This is a second diagram for explaining the operation of the link mechanism 200 . Figure 7 2 is a third diagram for explaining the operation of the link mechanism 200. The actuator 250 causes the rod 240 to move in a direction intersecting the rotation axis direction (in Figure 6 , Figure 7 In the vertical direction, the upper direction moves. Figure 6 as well as Figure 7 In the middle, rod 240 from Figure 5 The position shown is moved upward. Figure 6 Compared with the configuration of Figure 7The configuration of the rod 240 relative to Figure 5 The movement of the configuration is larger.

[0081] exist Figure 6 , Figure 7 When the rod 240 moves, the connecting member 230 moves upward via the rod connecting portion 234. At this time, the connecting member 230 is allowed to rotate with the rod connecting portion 234 as the rotation center. In addition, there is a slight play in the inner diameter of the bearing hole 242 of the rod 240 relative to the outer diameter of the rod connecting portion 234. Therefore, the connecting member 230 is slightly allowed to move in the plane direction perpendicular to the rotation axis direction.

[0082] As described above, the link mechanism 200 is a four-bar link mechanism. The connecting member 230, the first movable member 210, and the second movable member 220 exhibit one degree of freedom relative to the first housing member 110. Specifically, Figure 6 , Figure 7 In the embodiment, the connecting member 230 slightly rotates in the counterclockwise direction and slightly swings in the left and right directions within the above-mentioned allowable range.

[0083] The rotation shaft portion 214 in the first movable member 210 is axially supported by the first housing member 110. The rotation shaft portion 214 is restricted from moving in a plane direction perpendicular to the rotation axis direction. The connecting shaft portion 213 is axially supported by the connecting member 230. Since the movement of the connecting member 230 is allowed, the connecting shaft portion 213 is configured to be movable in a plane direction perpendicular to the rotation axis direction. As a result, Figure 6 , Figure 7 In the embodiment, along with the movement of the connecting member 230, the first movable member 210 rotates in the clockwise direction around the rotating shaft portion 214 as the rotation center.

[0084] Similarly, the rotation shaft portion 224 in the second movable member 220 is axially supported by the first housing member 110. The rotation shaft portion 224 is restricted from moving in a plane direction perpendicular to the rotation axis direction. The connecting shaft portion 223 is axially supported by the connecting member 230. Since the movement of the connecting member 230 is allowed, the connecting shaft portion 223 is provided to be movable in a plane direction perpendicular to the rotation axis direction. As a result, Figure 6 , Figure 7 In the embodiment, as the connecting member 230 moves, the second movable member 220 rotates in the clockwise direction around the rotating shaft portion 224 as the rotation center.

[0085] The first movable member 210 and the second movable member 220 are arranged according to Figure 6 , Figure 7 The protrusions 215 and 225 move radially outward from the protrusion position. Figure 7The position of the first movable member 210 and the second movable member 220 in the state shown in the figure is called the retracted position. In the retracted position, for example, the protrusions 215 and 225 are coplanar with the inner wall surface of the intake air path 130, or are located radially outward of the inner wall surface of the intake air path 130. In the retracted position, the first movable member 210 and the second movable member 220 are retracted from the intake air path 130. When moving from the retracted position to the protruding position, Figure 7 , Figure 6 , Figure 5 In this way, the positions of the first movable member 210 and the second movable member 220 are switched between the protruding position and the retracted position according to the rotation angle around the rotation shafts 214 and 224.

[0086] As described above, the first movable member 210 and the second movable member 220 are disposed in the intake air path 130 at a position closer to the intake port 10 than the compressor impeller 9. The first movable member 210 and the second movable member 220 are disposed in a manner covering the intake air path 130. In this way, the first movable member 210 and the second movable member 220 can move to a protruding position protruding into the intake air path 130 and a retracted position retracted from the intake air path 130. In the present embodiment, the first movable member 210 and the second movable member 220 move in the radial direction of the compressor impeller 9. However, this is not limited to this, and the first movable member 210 and the second movable member 220 may also rotate around the rotation axis of the compressor impeller 9. For example, the first movable member 210 and the second movable member 220 may also be shutter blades having two or more blades.

[0087] When the first movable member 210 and the second movable member 220 are located at the retracted position, they do not protrude into the intake flow path 130 , and thus it is possible to reduce the pressure loss of the air flowing in the intake flow path 130 .

[0088] In addition, if Figure 2 As shown, in the protruding position, the protruding portions 215 and 225 of the first movable member 210 and the second movable member 220 are disposed in the intake air path 130. When the first movable member 210 and the second movable member 220 are in the protruding position, the flow path cross-sectional area of ​​the intake air path 130 becomes smaller.

[0089] In the centrifugal compressor CC, as the flow rate of air flowing into the compressor impeller 9 decreases, the air compressed by the compressor impeller 9 may flow back in the intake air flow path 130. That is, the air compressed by the compressor impeller 9 may flow from the downstream side to the upstream side.

[0090] like Figure 2As shown, when the first movable member 210 and the second movable member 220 are in the protruding position, the protrusions 215 and 225 are located radially inward of the outermost diameter end of the leading edge LE of the compressor impeller 9. As a result, the air flowing back in the intake air path 130 is blocked by the protrusions 215 and 225. Therefore, the first movable member 210 and the second movable member 220 can suppress the backflow of the air in the intake air path 130.

[0091] In addition, since the flow path cross-sectional area of ​​the intake air path 130 is reduced, the flow velocity of the air flowing into the compressor impeller 9 increases. As a result, the generation of surging of the centrifugal compressor CC can be suppressed. That is, the centrifugal compressor CC of this embodiment can expand the working area of ​​the centrifugal compressor CC to the small flow side by forming a protruding position state.

[0092] As described above, the first movable member 210 and the second movable member 220 are configured as throttling members for throttling the intake air path 130. That is, in the present embodiment, the link mechanism 200 functions as a throttling mechanism for throttling the intake air path 130. The first movable member 210 and the second movable member 220 can change the flow path cross-sectional area of ​​the intake air path 130 by driving the link mechanism 200.

[0093] In the centrifugal compressor CC, when a strong backflow of air occurs in the intake air flow path 130, the backflow of air may not be sufficiently blocked by the movable components, namely the first movable component 210 and the second movable component 220. In this case, the efficiency of the centrifugal compressor CC is reduced. In this embodiment, the backflow of air is effectively suppressed by making an effort on the shape of the movable components, thereby effectively suppressing the reduction in the efficiency of the centrifugal compressor CC.

[0094] Below, refer to Figures 8 to 10 , the shape of the movable member for more effectively suppressing the backflow of air is described in detail. Figures 8 to 10 In FIG. 1 , only the first movable part 210 is shown as a movable part. Specifically, in Figures 8 to 10 , a cross section along the rotation axis of the compressor impeller 9 and passing through the curved portion 211 of the first movable member 210 is shown. However, the shape of the second movable member 220 is the same as that of the first movable member 210, and thus description thereof is omitted.

[0095] Figure 8 2 is a schematic cross-sectional view showing the details of the shape of the movable part. Figure 8As shown, a first end portion 216, a second end portion 217, and an extension portion 218 are formed on the inner circumferential surface S3 of the first movable member 210. The inner circumferential surface S3 is a surface between the opposing surface S1 and the opposing surface S2 in the surface of the protruding portion 215. The inner circumferential surface S3 connects the opposing surface S1 and the opposing surface S2. The opposing surface S1 and the opposing surface S2 extend in a direction orthogonal to the rotation axis of the compressor impeller 9.

[0096] The first end portion 216 is located on the compressor impeller 9 side of the inner peripheral surface S3 (at Figure 8 The first end 216 is an end portion (left side in the figure). The first end portion 216 is arranged on the inner circumferential surface S3 at a position closer to the compressor impeller 9 than the second end portion 217. The first end portion 216 has an annular shape centered on the rotation axis of the compressor impeller 9. The first end portion 216 has a first radius of curvature R1. The first end portion 216 has an arc shape with a radius of curvature of the first radius of curvature R1 in a cross section along the rotation axis of the compressor impeller 9. The first end portion 216 is equivalent to the R portion formed on the compressor impeller 9 side in the inner circumferential surface S3, i.e., the first R portion. The R portion is a portion having an arc shape in a cross section along the rotation axis of the compressor impeller 9.

[0097] The second end portion 217 is located on the air inlet 10 side of the inner peripheral surface S3 (at Figure 8 The second end 217 is arranged at a position on the inner circumferential surface S3 closer to the air inlet 10 than the first end 216. The second end 217 has a circular ring shape centered on the rotation axis of the compressor impeller 9. The second end 217 has a second curvature radius R2. The second curvature radius R2 is larger than the first curvature radius R1. In particular, Figure 8 In the example of , the second radius of curvature R2 is larger than the thickness T1 of the first movable member 210 in the rotation axis direction. The second end portion 217 has an arc shape having a curvature radius of the second radius of curvature R2 in a cross section along the rotation axis of the compressor impeller 9. The second end portion 217 corresponds to the R portion formed on the intake port 10 side of the inner circumferential surface S3, i.e., the second R portion.

[0098] The extension portion 218 is provided between the first end portion 216 and the second end portion 217. That is, the first end portion 216 and the second end portion 217 are connected by the extension portion 218. The extension portion 218 has a circular ring shape centered on the rotation axis of the compressor impeller 9. The extension portion 218 extends in a direction corresponding to the rotation axis direction of the compressor impeller 9. Figure 8In the example of , the extension direction of the extension portion 218 is the same direction as the rotation axis direction of the compressor impeller 9. However, the extension direction of the extension portion 218 may be inclined to a certain extent relative to the rotation axis direction of the compressor impeller 9. In this case, the extension direction of the extension portion 218 may also be a direction equivalent to the rotation axis direction of the compressor impeller 9. The extension portion 218 has a straight line shape extending in a direction equivalent to the rotation axis direction of the compressor impeller 9 in a cross section along the rotation axis of the compressor impeller 9.

[0099] The first end portion 216 connects the facing surface S2 and the extending portion 218. Figure 8 In the example of FIG. 2 , at the connection position between the first end portion 216 and the opposing surface S2, the tangent direction of the first end portion 216 is consistent with the extension direction of the opposing surface S2. However, at the connection position between the first end portion 216 and the opposing surface S2, the tangent direction of the first end portion 216 may be different from the extension direction of the opposing surface S2 to some extent.

[0100] exist Figure 8 In the example of FIG. 2 , at the connection position between the first end portion 216 and the extension portion 218, the tangent direction of the first end portion 216 is consistent with the extension direction of the extension portion 218. However, at the connection position between the first end portion 216 and the extension portion 218, the tangent direction of the first end portion 216 may be different from the extension direction of the extension portion 218 to some extent.

[0101] The second end portion 217 connects the facing surface S1 and the extending portion 218. Figure 8 In the example of FIG. 2 , at the connection position between the second end portion 217 and the facing surface S1 , the tangent direction of the second end portion 217 is different from the extending direction of the facing surface S1 . Fig. 9 yes Figure 8 The extracted image of the dotted part of Fig. 9 As shown, a rounded corner portion F1 having a small curvature radius is formed between the second end portion 217 and the facing surface S1. For example, the curvature radius of the rounded corner portion F1 may be the same as the first curvature radius R1 or may be smaller than the first curvature radius R1.

[0102] At the connection position between the second end portion 217 and the rounded corner portion F1, the tangent direction of the second end portion 217 is consistent with the tangent direction of the rounded corner portion F1. However, at the connection position between the second end portion 217 and the rounded corner portion F1, the tangent direction of the second end portion 217 may be different from the tangent direction of the rounded corner portion F1 to some extent. At the connection position between the rounded corner portion F1 and the opposing surface S1, the tangent direction of the rounded corner portion F1 is consistent with the extension direction of the opposing surface S1. However, at the connection position between the rounded corner portion F1 and the opposing surface S1, the tangent direction of the rounded corner portion F1 may be different from the extension direction of the opposing surface S1 to some extent. The rounded corner portion F1 may not be formed between the second end portion 217 and the opposing surface S1.

[0103] exist Figure 8 In the example of FIG. 2 , at the connection position between the second end portion 217 and the extension portion 218, the tangent direction of the second end portion 217 is consistent with the extension direction of the extension portion 218. However, at the connection position between the second end portion 217 and the extension portion 218, the tangent direction of the second end portion 217 may be different from the extension direction of the extension portion 218 to some extent.

[0104] As described above, the centrifugal compressor CC comprises: a first end 216, which is an end of the inner circumferential surface S3 of a movable component (the first movable component 210 in the above example) on the compressor impeller 9 side; a second end 217, which is an end of the inner circumferential surface S3 of the movable component on the air inlet 10 side; and an extension portion 218, which is arranged between the first end 216 and the second end 217 and extends in a direction corresponding to the direction of the rotation axis of the compressor impeller 9.

[0105] By providing the extension portion 218 between the first end portion 216 and the second end portion 217, the flow direction of the air flowing from the air intake port 10 toward the compressor impeller 9 can be guided along the rotation axis direction of the compressor impeller 9. Thus, the flow direction of the air flowing from the air intake port 10 toward the compressor impeller 9 can be suppressed from being excessively tilted radially inward as it approaches the compressor impeller 9. If the flow direction of the air flowing from the air intake port 10 toward the compressor impeller 9 is tilted as described above, the backflow area of ​​the air on the compressor impeller 9 side closer to the movable member (i.e., the area where the backflow of the air occurs) is easily expanded radially inward. Therefore, by guiding the flow direction of the air flowing from the air intake port 10 toward the compressor impeller 9 along the rotation axis direction of the compressor impeller 9, the backflow area of ​​the air on the compressor impeller 9 side closer to the movable member can be suppressed from expanding radially inward. Therefore, even if a strong backflow of air occurs in the intake air flow path 130, the backflow of the air can be fully blocked by the movable member, and the backflow of the air can be effectively suppressed. Therefore, it is achieved that the reduction in efficiency of the centrifugal compressor CC is effectively suppressed.

[0106] In particular, in the centrifugal compressor CC, the second curvature radius R2 which is the curvature radius of the second end portion 217 is larger than the first curvature radius R1 which is the curvature radius of the first end portion 216 .

[0107] By reducing the first curvature radius R1 of the first end portion 216, it is possible to suppress the air flowing back from the compressor impeller 9 toward the movable member from returning to the upstream side along the first end portion 216. That is, the air flowing back from the compressor impeller 9 toward the movable member can be effectively blocked by the opposing surface S2. From the viewpoint of effectively blocking the reverse air by the opposing surface S2, it is preferred that the first curvature radius R1 of the first end portion 216 is as small as possible. For example, the first curvature radius R1 is preferably less than 1 mm, and more preferably less than 0.1 mm. The first curvature radius R1 may also be 0 mm.

[0108] By increasing the second radius of curvature R2 of the second end portion 217, the air flowing from the air inlet 10 toward the compressor impeller 9 tends to flow along the second end portion 217. As a result, it is possible to suppress the air from peeling off at the second end portion 217, so that the position where the air is peeled off in the inner circumferential surface S3 of the movable component can be located further downstream. If the air is peeled off on the upstream side of the inner circumferential surface S3 of the movable component, the backflow area of ​​the air on the compressor impeller 9 side of the movable component tends to expand radially inward. Therefore, by setting the position where the air is peeled off in the inner circumferential surface S3 of the movable component to be further downstream, it is possible to suppress the backflow area of ​​the air on the compressor impeller 9 side of the movable component from expanding radially inward.

[0109] As described above, by making the curvature radius of the second end portion 217, i.e., the second curvature radius R2, larger than the curvature radius of the first end portion 216, i.e., the first curvature radius R1, the backflow of air can be sufficiently blocked by the movable member, and the backflow of air can be more effectively suppressed. Therefore, the reduction in efficiency of the centrifugal compressor CC can be more effectively suppressed.

[0110] In particular, in the centrifugal compressor CC, the radius of curvature of the second end portion 217, i.e., the second radius of curvature R2, is larger than the thickness T1 of the movable member (the first movable member 210 in the above example) in the direction of the rotation axis. As a result, the air flowing from the air inlet 10 toward the compressor impeller 9 is more likely to flow along the second end portion 217. Therefore, it is possible to further suppress the air from being separated at the second end portion 217, so that the position of the air separation in the inner peripheral surface S3 of the movable member can be located further downstream. Therefore, it is possible to further suppress the expansion of the backflow area of ​​the air on the compressor impeller 9 side of the movable member to the radial inner side.

[0111] In particular, in the centrifugal compressor CC, a fillet portion F1 is formed between the second end portion 217 and the surface (the opposing surface S1 in the above example) of the movable member (the first movable member 210 in the above example) facing the air inlet 10. Thus, compared with the case where the fillet portion F1 is not formed, it is possible to suppress the air from being separated at the connection position between the second end portion 217 and the opposing surface S1. Therefore, it is possible to appropriately set the position where the air is separated in the inner peripheral surface S3 of the movable member on the downstream side. Therefore, it is possible to appropriately suppress the expansion of the backflow area of ​​the air on the compressor impeller 9 side of the movable member to the radial inside.

[0112] In particular, in the centrifugal compressor CC, the radial distance D1 between the inner circumferential end E1 of the surface (the opposing surface S1 in the above example) of the movable member (the first movable member 210 in the above example) facing the air inlet 10 and the extension portion 218 is equal to or less than the upper limit value corresponding to the thickness T1 of the movable member in the rotation axis direction and equal to or greater than the lower limit value corresponding to the thickness T1 of the movable member in the rotation axis direction. However, for the above radial distance D1, only the upper limit value may be set, or only the lower limit value may be set.

[0113] If the above-mentioned radial distance D1 becomes too long, it will be difficult to guide the flow direction of the air flowing from the air inlet 10 toward the compressor impeller 9 along the direction of the rotation axis of the compressor impeller 9. Therefore, from the viewpoint of achieving the guidance of the flow direction of the air flowing from the air inlet 10 toward the compressor impeller 9 along the direction of the rotation axis of the compressor impeller 9, the upper limit value of the radial distance D1 is appropriately set. For example, the upper limit value of the radial distance D1 can be set to 80% of the thickness T1. By setting the above-mentioned radial distance D1 to less than the upper limit value (for example, less than 80% of the thickness T1), it is possible to appropriately achieve the guidance of the flow direction of the air flowing from the air inlet 10 toward the compressor impeller 9 along the direction of the rotation axis of the compressor impeller 9.

[0114] If the radial distance D1 described above becomes too short, the air on the upstream side of the inner circumferential surface S3 of the movable member is easily separated. Therefore, from the viewpoint of making the position where the air is separated in the inner circumferential surface S3 of the movable member further downstream, the lower limit value of the radial distance D1 is appropriately set. For example, the lower limit value of the radial distance D1 can be set to 20% of the thickness T1. By setting the radial distance D1 described above to a value greater than the lower limit value (for example, greater than 20% of the thickness T1), it is possible to appropriately achieve the position where the air is separated in the inner circumferential surface S3 of the movable member further downstream.

[0115] Fig.10 2 is a schematic cross-sectional view showing the shape of a movable part according to a modified example. Fig.10 In the modified example shown, Figure 8 Compared with the example of , the difference is that the groove 219 is added. Fig.10 As shown, in the modified example, a groove 219 is provided on the opposing surface S1 of the first movable member 210. The groove 219 is recessed from the opposing surface S1 toward the opposing surface S2. For example, the groove 219 is formed by extending in the circumferential direction at the curved portion 211. By forming the groove 219 in the movable member (for example, the first movable member 210), deformation caused by heat shrinkage when the movable member is molded by injection molding can be suppressed.

[0116] In particular, Fig.10 In the modified example shown, Figure 8 Similarly to the example, the second radius of curvature R2 is larger than the thickness T1 of the movable member (the first movable member 210 in the above example) in the direction of the rotation axis. Therefore, it is easy to increase the second radius of curvature R2 of the second end portion 217. As a result, compared with the case where the second radius of curvature R2 is smaller than the thickness T1, it is easy to make the inner circumferential surface S3 of the movable member closer to the groove portion 219 as a whole, and it is easy to make the radial distance between the inner circumferential surface S3 of the movable member and the groove portion 219 as a whole smaller. Therefore, it is possible to more effectively suppress deformation caused by heat shrinkage when the movable member is molded by injection molding.

[0117] The embodiments of the present disclosure are described above with reference to the accompanying drawings, but the present disclosure is of course not limited to the embodiments. It is obvious that those skilled in the art can think of various changes or modifications within the scope of the technical solution, and of course they are understood to belong to the technical scope of the present disclosure.

[0118] Explanation of symbols

[0119] 9—compressor impeller, 10—air inlet, 130—intake air path, 210—first movable component (movable component), 216—first end, 217—second end, 218—extension portion, 220—second movable component (movable component), CC—centrifugal compressor, D1—radial distance, E1—inner peripheral end, F1—rounded corner, S3—inner peripheral surface, T1—thickness.

Claims

1. A centrifugal compressor, characterized in that: have: an intake air flow path connected to the air intake port; a compressor impeller, disposed in the intake air path; a movable member provided at a position closer to the air inlet than the compressor impeller in the air intake passage, and capable of moving to a protruding position protruding into the air intake passage and a retracted position retracted from the air intake passage; a first end portion, which is an end portion of the inner peripheral surface of the movable member on the compressor impeller side; a second end portion, which is an end portion of the inner peripheral surface of the movable member on the air inlet side; as well as The extension portion is provided between the first end portion and the second end portion and extends in a direction corresponding to a rotation axis direction of the compressor impeller.

2. The centrifugal compressor according to claim 1, characterized in that: The second end portion has a greater radius of curvature than the first end portion.

3. The centrifugal compressor according to claim 2, characterized in that: The curvature radius of the second end portion is larger than the thickness of the movable member in the rotation axis direction.

4. The centrifugal compressor according to claim 3, characterized in that: A rounded portion is formed between the second end portion and a surface of the movable member that faces the air inlet side.

5. The centrifugal compressor according to any one of claims 2 to 4, characterized in that: A radial distance between an inner peripheral end of a surface of the movable member facing the air inlet side and the extending portion is equal to or less than 80% of a thickness of the movable member in the rotation axis direction.

6. The centrifugal compressor according to any one of claims 2 to 4, characterized in that: A radial distance between an inner peripheral end of a surface of the movable member facing the air inlet side and the extending portion is equal to or greater than 20% of a thickness of the movable member in the rotation axis direction.

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