JP2016205271A - Centrifugal compressor and turbocharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a centrifugal compressor capable of suppressing occurrence of surging, and a turbocharger.SOLUTION: By closing a communication hole 60 with a closing member 66, backflowing force acting on compressed air having passed through a winding start part 54A on the side of a winding end part 54B is weakened. Consequently, when the closing member 66 is arranged at a closing position, occurrence of backflow is suppressed, and then occurrence of surging is suppressed.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a centrifugal compressor and a turbocharger.

  Patent Document 1 describes a centrifugal compressor having a scroll structure. In this centrifugal compressor, the height of the flow path connecting portion where the winding start and the winding end of the scroll structure intersect is the same as the height of the diffuser outlet.

JP2012-140900A

  However, since the winding start portion and the winding end portion side communicate with each other in the scroll-structure flow path (spiral flow path), a part of the air flowing through the scroll-structure flow path and going to the outlet is In some cases, surging may occur due to backflow in the portion (flow path connecting portion) where the end portion is in communication.

  The subject of this invention is suppressing generation | occurrence | production of surging in a centrifugal compressor.

  The centrifugal compressor according to claim 1 of the present invention rotates around an axis, compresses air flowing in from the axial direction, and flows it to the outside in the radial direction, a winding start portion, and a winding end from which air is discharged. A casing in which a spiral flow path is formed in which a spiral flow is made in communication with the part side through a communication hole, and the air flowed by the rotor blades outward in the radial direction is formed, and a closing member that closes the communication hole And.

  According to the above configuration, the winding start portion and the winding end portion side communicate with each other through the communication hole in the spiral flow path. And since a closing member closes this communicating hole, it is suppressed that the air which flows through a spiral flow path flows back in the vicinity of a communicating hole. By suppressing this backflow, it is possible to suppress the occurrence of surging in the centrifugal compressor.

  A centrifugal compressor according to a second aspect of the present invention is the centrifugal compressor according to the first aspect, wherein the closing member is between a closed position for closing the communication hole and an open position for opening the communication hole. It is possible to move.

  According to the above configuration, the closing member is movable between a closing position for closing the communication hole and an opening position for opening the communication hole. Thereby, a closing member can be appropriately moved to a closed position or an open position.

  A centrifugal compressor according to a third aspect of the present invention is the centrifugal compressor according to the second aspect, wherein the moving member that moves the closing member to the closed position and the open position, the pressure ratio, and the spiral flow path. And a controller that controls the moving member based on a flow rate of air flowing through the moving member and moves the closing member to the moving member.

  According to the above configuration, the control unit can control the moving member based on the pressure ratio and the flow rate of the air flowing through the spiral flow path.

  According to a fourth aspect of the present invention, there is provided a turbocharger comprising: a turbine unit having a turbine rotor that is rotated by a force of exhaust gas exhausted from an engine; and a rotational force transmitted from the turbine rotor to the rotor blades. The centrifugal compressor of any one of Claims 1-3 which compresses the air to supply, It is characterized by the above-mentioned.

  According to the said structure, the turbocharger is provided with the centrifugal compressor of any one of Claims 1-3. Thereby, generation | occurrence | production of the surging in a centrifugal compressor is suppressed, and compressed air can be efficiently supplied to an engine.

  According to the present invention, it is possible to suppress the occurrence of surging in a centrifugal compressor having a spiral flow path.

(A) (B) It is the expansion perspective view which showed a part of spiral flow path of the centrifugal compressor which concerns on 1st Embodiment of this invention. (A) (B) It is the enlarged plan view which showed a part of centrifugal compressor which concerns on 1st Embodiment of this invention. (A) (B) It is the enlarged plan view which showed a part of centrifugal compressor which concerns on 1st Embodiment of this invention. It is drawing which showed the surging limit of the centrifugal compressor which concerns on 1st Embodiment of this invention with the graph. It is the perspective view which showed the spiral flow path of the centrifugal compressor which concerns on 1st Embodiment of this invention. It is the top view which showed the centrifugal compressor which concerns on 1st Embodiment of this invention. It is the block diagram which showed the turbocharger which concerns on 1st Embodiment of this invention. It is the expansion perspective view which showed a part of spiral flow path of the centrifugal compressor which concerns on 2nd Embodiment of this invention. (A) (B) It is sectional drawing which showed the spiral flow path of the centrifugal compressor which concerns on 2nd Embodiment of this invention.

<First Embodiment>
An example of the centrifugal compressor and the turbocharger according to the first embodiment of the present invention will be described with reference to FIGS.

(overall structure)
As shown in FIG. 7, the turbocharger 10 according to the first embodiment includes a turbine unit 20, a centrifugal compressor 30, and a connecting unit 40 that connects the turbine unit 20 and the centrifugal compressor 30. . The turbine unit 20 is disposed in the middle of the exhaust passage 12 of an automobile engine (not shown), and the centrifugal compressor 30 is disposed in the middle of the intake passage 14 of the engine.

  The turbine unit 20 includes a turbine housing 24, the centrifugal compressor 30 includes a compressor housing 50 that is a casing, and the connection unit 40 includes a connection housing 44 that connects the compressor housing 50 and the compressor housing 50. . The turbine housing 24, the connecting housing 44, and the compressor housing 50 are fixed to each other by a fixture (not shown).

  In addition, the axial direction of the rotating shaft 42 described later (the direction of arrow C in the drawing: hereinafter simply referred to as “axial direction”) is the same as the arrangement direction of the turbine housing 24, the connecting housing 44, and the compressor housing 50. The turbine housing 24, the connecting housing 44, and the compressor housing 50 are arranged in this order from one end side in the axial direction (right side in the figure) to the other end side (left side in the figure).

[Turbine unit]
As shown in FIG. 7, the turbine unit 20 includes a turbine housing 24, and the turbine housing 24 is hollow inside. A turbine rotor 22 is disposed inside the turbine housing 24. The turbine rotor 22 includes a rotor shaft portion 28 that is fixed to a portion on one end side (right side in the drawing) of the rotating shaft 42 that is formed in a columnar shape, and a plurality of turbine blades that extend from the rotor shaft portion 28. 26. And between the adjacent turbine blades 26, exhaust gas (an example of fluid) discharged from the engine flows. The turbine rotor 22 and the rotating shaft 42 are integrally rotated within the turbine housing 24.

  Further, in the turbine housing 24, the exhaust gas flowing through the exhaust passage 12 is transferred to the turbine housing 24 in a portion outside the radial direction of the rotary shaft 42 with respect to the turbine rotor 22 (arrow D direction in the drawing: hereinafter simply “radial direction”). A spiral spiral flow path 24 </ b> A that flows into the interior is formed. Further, an exhaust passage 24 </ b> B that exhausts exhaust gas to the outside of the turbine housing 24 is formed in a portion of the turbine housing 24 that is axially outer (right side in the drawing) with respect to the turbine rotor 22.

  In this configuration, the exhaust gas flowing into the turbine housing 24 from the spiral flow path 24A presses the plurality of turbine blades 26 to rotate the turbine rotor 22 and is discharged from the discharge flow path 24B. That is, the turbine rotor 22 is a so-called radial turbine rotor.

[Connecting unit]
As shown in FIG. 7, the connection unit 40 includes a connection housing 44. And this connection housing 44 has the support part 44A which supports the rotating shaft 42 rotatably.

  Furthermore, the connection housing 44 has an inflow port (not shown) through which the circulating engine oil flows into the connection housing 44 and a discharge port (not shown) through which the engine oil is discharged from the connection housing 44. .

  In this configuration, the engine oil that has flowed into the connection housing 44 is supplied to the support portion 44A so that the rotating shaft 42 rotates smoothly.

(Centrifuge compressor)
As shown in FIG. 7, the centrifugal compressor 30 includes a compressor housing 50 as an example of a housing, and the compressor housing 50 has a hollow inside. An impeller 32 is disposed inside the compressor housing 50. The impeller 32 has a rotating shaft portion 34 fixed to the other end side (left side in the drawing) of the rotating shaft 42 and a plurality of impeller blades 36 extending from the rotating shaft portion 34. This impeller blade 36 is an example of a rotary blade.

  Further, in the compressor housing 50, an inflow passage 52 through which air flowing through the intake passage 14 flows into the compressor housing 50 is formed on the outer side (left side in the drawing) in the axial direction with respect to the impeller 32.

  Further, in the compressor housing 50, a spiral spiral flow path 54 (so-called scroll flow) that discharges compressed air compressed by the rotating impeller 32 to the outside of the compressor housing 50 is provided at a portion radially outside the impeller 32. Road) is formed.

  In this configuration, the air flowing into the compressor housing 50 from the inflow channel 52 is compressed by the rotating impeller blades 36 and discharged from the spiral channel 54 as compressed air.

  Details of the centrifugal compressor 30 will be described later.

(Operation of the overall configuration)
Next, the operation of the turbocharger 10 will be described.

  The exhaust gas flowing through the exhaust passage 12 flows into the turbine housing 24 from the spiral flow path 24 </ b> A and presses the turbine blades 26. As a result, the turbine rotor 22 rotates, and this rotation is transmitted to the impeller 32 via the rotating shaft 42. The exhaust gas that has rotated the turbine rotor 22 inside the turbine housing 24 is discharged from the discharge passage 24B.

  The impeller 32 that rotates when the rotation is transmitted through the rotation shaft 42 compresses the air that flows into the compressor housing 50 from the inflow passage 52 by the impeller blades 36. The compressed air compressed by the rotating impeller 32 flows through the spiral flow path 54 and is discharged to the intake passage 14. The compressed air discharged from the spiral flow path 54 is supplied to the engine as compressed air for combustion.

(Main part configuration)
Next, the centrifugal compressor 30 will be described.

  The centrifugal compressor 30 includes a compressor housing 50, an impeller 32 disposed inside the compressor housing 50, and a closing member 66 (see FIG. 1A) that closes the communication hole 60 formed in the compressor housing 50. I have.

[Impeller]
As shown in FIG. 7, the impeller 32 includes a rotating shaft portion 34 and a plurality of impeller blades 36 whose proximal end portions are connected to the rotating shaft portion 34.

  The rotating shaft portion 34 is tapered while reducing the rate of gradually decreasing toward the outer side in the axial direction (left side in the figure).

  Further, as shown in FIG. 6, the impeller blades 36 extend radially outward from the rotating shaft portion 34.

  As shown in FIG. 7, each impeller blade 36 includes a tip edge 36 </ b> A having an end surface facing outward in the axial direction at a tip side (air inflow side) portion of the impeller blade 36, and a tip edge 36 </ b> A. It has a curved edge 36B that is connected to the end portion and is curved toward the proximal end portion of the impeller blade 36. Further, each impeller blade 36 has a base end edge 36C that is connected to the end of the curved edge 36B and whose end face faces radially outward.

  In this configuration, the rotating impeller 32 compresses air flowing in from the tip edge 36A side of the impeller blade 36, and flows the compressed air from the base end edge 36C of the impeller blade 36 to the outside in the radial direction.

[Compressor housing]
As shown in FIG. 7, the compressor housing 50 includes an inflow channel 52, a diffusion channel 56 (a so-called diffuser channel), and a spiral channel 54.

  As shown in FIG. 6, the inflow channel 52 has a circular shape with the rotation shaft portion 34 as the center when viewed from the axial direction, and extends to the impeller 32 from the outside in the axial direction (front side in the drawing) with respect to the impeller 32. It is designed to guide the air. Thereby, the impeller 32 flows in air from the outer side in the axial direction.

  The diffusion channel 56 is formed so as to surround the impeller 32 when viewed from the axial direction, and guides the compressed air that has been compressed by the rotating impeller 32 and flowed outward in the radial direction to the spiral channel 54. . The flow path width (length in the axial direction) of the diffusion flow path 56 is constant as shown in FIG.

  As shown in FIG. 6, the spiral flow path 54 is formed in a spiral shape so as to surround the diffusion flow path 56 when viewed from the axial direction, and the cross section of the spiral flow path 54 is as shown in FIG. It is round.

  Specifically, as shown in FIG. 6, the spiral channel 54 is wound clockwise from the winding start portion 54 </ b> A having the smallest channel cross section in the spiral channel 54. It passes through 54A and extends linearly. The end portion extending linearly is the winding end portion 54 </ b> B of the spiral flow channel 54.

  Furthermore, the size of the cross-section of the spiral flow channel 54 gradually increases from the winding start portion 54A to the winding end portion 54B. And the spiral flow path 54 is open | released outside by the winding end part 54B.

  Further, the diameter of the cross section of the flow path of the winding start portion 54A is made larger than the flow path width of the diffusion flow path 56, and the diffusion flow path 56 has a rotational axis in the spiral flow path 54 as shown in FIG. It communicates with the portion of the base end side (right side in the figure) of 42 in the axial direction.

  FIG. 5 shows a spiral channel 54. As shown in FIG. 5, the wall on the winding end portion 54B side of the spiral flow path 54 is in contact with the winding start portion 54A. A circular communication hole 60 that allows the winding start portion 54A and the winding end portion 54B to communicate with each other is formed in the wall on the winding end portion 54B side of the spiral flow path 54.

  In this configuration, the compressed air flowing radially outward from the base end edge 36 </ b> C of the rotating impeller blade 36 flows into the spiral channel 54 through the diffusion channel 56, flows through the spiral channel 54, and flows through the spiral channel 54. 54 is discharged from the winding end portion 54B.

(Closing member)
As shown in FIG. 6, the closing member 66 is disposed in a portion on the winding end portion 54 </ b> B side in the spiral flow path 54 and closes the communication hole 60.

  Specifically, the closing member 66 includes a curved curved plate 66A along the wall surface of the spiral flow path 54, as shown in FIG. Further, the closing member 66 includes a support member 66 </ b> B having one end fixed to the curved plate 66 </ b> A and the other end exposed to the outside of the spiral channel 54 through the slit 62 formed on the wall surface of the spiral channel 54. .

  The slit 62 extends in the direction in which the compressed air flows in the spiral flow path 54 (the left-right direction in the drawing), and the support member 66B can move in the slit 62 in the direction in which the slit 62 extends. . Thereby, the closing member 66 can be moved between a closed position (see FIG. 1A) for closing the communication hole 60 and an open position (see FIG. 1B) for opening the communication hole 60. ing.

[Others]
As illustrated in FIG. 1A, the centrifugal compressor 30 includes a moving member 70 that moves the closing member 66 and a control unit 72 that controls the moving member 70.

  The moving member 70 is disposed outside the spiral flow path 54, and moves the other end of the supporting member 66B to move the closing member 66.

  The moving member 70 moves the closing member 66 to the closing position or the opening position under the control of the control unit 72. In addition, control with respect to the moving member 70 by the control part 72 is demonstrated with the effect | action mentioned later.

(Function)
Next, the operation of the centrifugal compressor 30 will be described.

  First, the surging limit of the centrifugal compressor 30 will be described.

  The vertical axis of the graph shown in FIG. 4 indicates the pressure ratio of air by the centrifugal compressor 30, and the horizontal axis indicates the flow rate [Kg / sec] of compressed air discharged from the winding end portion 54B of the centrifugal compressor 30. Yes.

  The broken line G1 in the graph shown in FIG. 4 indicates the flow rate and pressure ratio of the compressed air when the rotational speed of the impeller 32 is constant and the flow rate of the compressed air discharged from the centrifugal compressor 30 is changed (in the centrifugal compressor 30). It shows the relationship between the ratio P2 / P1) of the pressure P2 at the gas outlet and the pressure P1 at the inlet. Then, the flow rate of compressed air was gradually reduced, and the flow rate of compressed air and the pressure ratio at which surging occurred were detected. That is, the flow rate of compressed air was reduced until surging occurred. That is, in the broken line G1, surging has occurred at the point g1 where the flow rate of compressed air is the smallest. The occurrence of surging was judged visually.

  The broken line G2 has a higher rotational speed than the broken line G1, and the broken line G3 has a higher rotational speed than the broken line G2. In the broken line G2, surging occurs at the point g2 where the flow rate of compressed air is the smallest, and in the broken line G3, surging occurs at the point g3 where the flow rate of compressed air is the smallest.

  Further, the operation similar to the broken lines G1 to G3 is performed at other rotational speeds, and surging is performed when the closing member 66 is disposed at the closed position and when the closing member 66 is disposed at the open position. The flow rate and pressure ratio of the generated compressed air were determined.

  A solid line H1 in the graph is a surging limit line H1 (hereinafter referred to as “limit line H1”) when the closing member 66 is disposed at the closing position, and a solid line H2 in the graph is the opening position of the closing member 66. Is a surging limit line H <b> 2 (hereinafter “limit line H <b> 2”).

  When the closing member 66 is disposed at the closing position, the centrifugal compressor 30 can be used without generating surging in the area on the right side (the larger flow rate side) of the limit line H1 in the graph. . Further, when the closing member 66 is disposed at the open position, the centrifugal compressor 30 can be used without causing surging in the area on the right side of the limit line H2 in the graph.

  Here, when the limit line H1 and the limit line H2 are compared, by closing the communication hole 60 with the closing member 66, the surging is performed in the shaded range J in the graph as compared with the case where the closing member 66 is not used. It can be seen that the occurrence is suppressed.

  Next, the reason why surging occurs when the flow rate of the compressed air is reduced with the rotation speed of the impeller 32 being the same will be described.

  When the flow rate of the compressed air decreases, an excessive deceleration flow (the flow velocity decreases toward the downstream) from the winding start portion 54A to the winding end portion 54B of the spiral flow path 54, and the pressure at the winding start portion 54A is changed to the winding end portion 54B. Lower than the pressure at. As a result, a reverse flow (flow in a direction opposite to the flow direction) occurs on the winding end portion 54B side of the spiral flow path 54. Then, surging occurs due to the backflow.

  Here, when the closing member 66 is disposed at the open position, the winding start portion 54 </ b> A and the winding end portion 54 </ b> B are communicated with each other through the communication hole 60. For this reason, a backflow force acts from the winding end portion 54B side to the winding start portion 54A side. As a result, when the closing member 66 is disposed at the open position, backflow is more likely to occur than when the closing member 66 is disposed at the closed position (see FIG. 2A).

  Further, by closing the communication hole 60 with the closing member 66, the backflow force acting on the compressed air that has passed through the winding start portion 54A on the winding end portion 54B side is weakened. Thereby, when the closing member 66 is arrange | positioned in the closing position, generation | occurrence | production of a backflow is suppressed (refer FIG. 2 (B)).

  If the flow rate of the compressed air is increased, the flow increases from the winding start portion 54A to the winding end portion 54B of the spiral flow path 54, and the pressure at the winding start portion 54A becomes higher than the pressure at the winding end portion 54B. As a result, almost no backflow occurs on the winding end portion 54B side of the spiral flow path 54.

  Next, the compression efficiency in the case where the rotational speed of the impeller 32 is increased and the flow rate of the compressed air is increased will be described.

  As described above, when the flow rate of the compressed air is increased, the flow increases from the winding start portion 54A to the winding end portion 54B of the spiral flow path 54, and the pressure at the winding start portion 54A is higher than the pressure at the winding end portion 54B. Become.

  For this reason, on the winding end portion 54B side, the flow rate of the compressed air is increased, so that the frictional force generated between the spiral flow path 54 and the wall surface is increased. In particular, when the closing member 66 is disposed at the closing position, the flow of compressed air has a large angle of attack with respect to the distal end portion of the closing member 66, so that the effective area of the flow path on the winding end portion 54 </ b> B side. Since the speed of the compressed air increases due to the decrease, the frictional force generated between the spiral flow path 54 and the wall surface of the spiral flow path 54 increases, and the compression efficiency may decrease.

  Here, by disposing the closing member 66 in the open position and opening the communication hole 60, the compressed air flows on the winding end portion 54B side through the communication hole 60 to the winding start portion 54A side (FIG. 3B). Since the effective area of the flow path on the winding end portion 54B side is increased, the speed of the compressed air is reduced, so that the frictional force generated between the compressed air and the wall surface of the spiral flow path 54 is reduced and the compression is performed. It is suppressed that efficiency falls.

  As described above, when the flow rate of the compressed air is increased, the reduction of the compression efficiency is suppressed by arranging the closing member 66 at the open position.

  Here, in a state where the centrifugal compressor 30 is not in operation, for example, the closing member 66 is disposed at the open position. Further, the control unit 72 (see FIG. 1) stores in advance the graph shown in FIG. 4 as mapping data. When the centrifugal compressor 30 is operated, the control unit 72 monitors the flow rate and pressure ratio of the compressed air detected by an air flow sensor and a pressure sensor (not shown). When the flow rate of compressed air and the pressure ratio are in the hatched range K (range where surging is likely to occur) in the graph shown in FIG. 4, the control unit 72 moves the closing member 66 to the closing position (FIG. 1 ( A)). On the other hand, when the flow rate of compressed air and the pressure ratio are out of the hatched range K in the graph shown in FIG. 4, the control unit 72 maintains the state where the closing member 66 is disposed at the open position. (See FIG. 1B).

  And the control part 72 controls the moving member 70 by monitoring the flow volume and pressure ratio of compressed air, and moves the closing member 66 to a closed position or an open position.

(Summary)
As described above, the centrifugal compressor 30 includes the closing member 66 that closes the communication hole 60. Thereby, compared with the case where the communicating hole 60 is open | released, generation | occurrence | production of surging can be suppressed.

  Further, when the flow rate and pressure ratio of the compressed air are in the hatched range K in the graph shown in FIG. 4, the control unit 72 moves the closing member 66 to the closing position. On the other hand, when the flow rate of compressed air and the pressure ratio are out of the hatched range K in the graph shown in FIG. 4, the control unit 72 maintains the state where the closing member 66 is disposed at the open position. . Thereby, after suppressing generation | occurrence | production of surging, the fall of the compression efficiency at the time of a large flow volume can be suppressed.

  Further, in the turbocharger 10, the occurrence of surging in the centrifugal compressor 30 is suppressed, so that compressed air can be efficiently supplied to the engine.

Second Embodiment
Next, an example of a centrifugal compressor and a turbocharger according to the second embodiment of the present invention will be described with reference to FIGS. In addition, about the same member as 1st Embodiment, the same code | symbol is attached | subjected, the description is abbreviate | omitted, and a different part from 1st Embodiment is mainly demonstrated.

(Constitution)
As shown in FIG. 8, the closing member 106 of the centrifugal compressor 100 according to the second embodiment includes a curved plate 106 </ b> A along the wall surface of the spiral flow path 54. Further, the closing member 106 includes a support member 106 </ b> B having one end fixed to the curved plate 106 </ b> A and the other end exposed to the outside of the spiral channel 54 through the slit 110 formed in the wall surface of the spiral channel 54. .

  The curved plate 106A is formed to extend in the circumferential direction of the spiral flow path 54, and a circular through hole 107 is formed in the curved plate 106A. The slit 110 extends in the circumferential direction of the spiral flow path 54, and the support member 106 </ b> B can move inside the slit 110.

  Further, the centrifugal compressor 100 includes a moving member 108 that moves the closing member 106 in the circumferential direction of the spiral flow path 54 as shown in FIGS.

  In this configuration, the moving member 108 opens the closing member 106 through the closing position (see FIG. 9A) where the communication hole 60 is closed and the through hole 107 formed in the curved plate 106A. The position is moved between the positions (see FIG. 9B). The other operations in the second embodiment are the same as those in the first embodiment.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments can be taken within the scope of the present invention. This will be apparent to those skilled in the art. For example, in the above embodiment, the moving members 70 and 108 move the closing members 66 and 106, but the centrifugal compressors 30 and 100 may not include the moving members 70 and 108. In this case, the closing members 66 and 106 may be moved as appropriate.

  In the above-described embodiment, the moving members 70 and 108 move the closing members 66 and 106 to the closed position or the open position. However, the moving members 70 and 108 move to an intermediate position (half-open) between the closed position and the open position. You may let them.

  Moreover, in the said embodiment, although the control part 72 controlled the moving members 70 and 108 based on the pressure ratio and the flow volume of compressed air, the control part 72 controlled the moving members 70 and 108 based on other information. May be controlled.

DESCRIPTION OF SYMBOLS 10 Turbocharger 20 Turbine unit 22 Turbine rotor 30 Centrifugal compressor 36 Impeller blade | wing (an example of rotary blade)
50 Compressor housing (example of housing)
54 spiral flow path 54A winding start portion 54B winding end portion 60 communication hole 66 closing member 70 moving member 72 control unit 100 centrifugal compressor 106 closing member 108 moving member

Claims (4)

A rotating blade that rotates around an axis, compresses air flowing in from the axial direction, and flows it outward in the radial direction;
A casing having a spiral shape in which a winding start portion and a winding end portion side from which air is discharged are communicated with each other through a communication hole, and a spiral flow path is formed in which the air flowed by the rotary blades outward in the radial direction is formed. Body,
A closing member for closing the communication hole;
A centrifugal compressor.   The centrifugal compressor according to claim 1, wherein the closing member is movable between a closing position for closing the communication hole and an opening position for opening the communication hole. A moving member that moves the closing member to the closing position and the opening position;
A control unit that controls the moving member based on a pressure ratio and a flow rate of air flowing through the spiral flow path, and moves the closing member to the moving member;
The centrifugal compressor according to claim 2 provided with. A turbine unit having a turbine rotor that is rotated by a force through which exhaust gas discharged from the engine flows;
The centrifugal compressor according to any one of claims 1 to 3, wherein a rotational force is transmitted from the turbine rotor to the rotor blades to compress air supplied to the engine.
Turbocharger with

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