JP2018059482A - Centrifugal compressor and turbocharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a centrifugal compressor capable of suppressing occurrence of surging with deterioration of compression efficiency of compressing air suppressed, and provide a turbocharger.SOLUTION: When a movement member is moved in a radial direction to minimize a flow passage area of an inflow passage, pressure of air flowing into an impeller increases to suppress occurrence of surging. For example, in terms of suppression of deterioration of compression efficiency of compressing air and suppression of occurrence of surging, the movement member is configured to be moved to a position where the flow passage area is appropriate. Consequently, with deterioration of the compression efficiency of compressing air suppressed, occurrence of surging is suppressed.SELECTED DRAWING: Figure 1

Description

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

  The centrifugal compressor described in Patent Document 1 is a centrifugal compressor that compresses air by rotation of an impeller, and is provided in an introduction pipe that introduces air into the impeller, and the flow of air on the upstream side of the impeller And a regulating member that is displaced between a state in which the flow of air is regulated and a state in which the air flow is not regulated.

JP 2010-138765 A

  In a centrifugal charger for a turbocharger, when the flow rate of compressed air is reduced by an impeller that rotates at a predetermined rotational speed, the pressure on the outlet side of the centrifugal compressor increases. As a result, a part of the air flows backward from the impeller outlet through the gap between the impeller and the housing to the inlet side of the impeller. Due to the backflow, surge compression may occur in the centrifugal compressor.

  The subject of this invention is suppressing generation | occurrence | production of surging, after suppressing the fall of the compression efficiency which compresses air.

  The centrifugal compressor according to claim 1 of the present invention is disposed on the upstream side of the impeller in the air flow direction, and an impeller that rotates around the axis and compresses air flowing in from the axial direction and flows in the radial direction. A moving member that moves in the radial direction and changes a flow passage area of an inflow flow passage that guides air to the impeller, and the flow passage area is minimized when the moving member minimizes the flow passage area. Is smaller than the area of the entrance of the impeller.

  According to the above configuration, the rotating impeller compresses the air flowing into the impeller. The rotating impeller compresses the flowing air and flows it in the radial direction.

  When the flow rate of the compressed air compressed by the impeller is small, the compressed air that has flowed in the radial direction from the impeller is divided into air that continues to flow in the radial direction and air that is folded in the opposite direction and flows to the inflow channel side (separation). To do). Surging may occur due to the air flow in the opposite direction.

  Here, when the moving member is moved in the radial direction to minimize the channel area of the inflow channel, the channel area becomes smaller than the area of the inlet of the impeller. As a result, the pressure of the air flowing into the impeller increases, and the amount of air flowing in the reverse direction described above decreases. And generation | occurrence | production of surging is suppressed.

  Then, for example, the moving member is moved to a position where the flow path area is suitable from the viewpoint of suppressing a decrease in compression efficiency for compressing air and suppressing the occurrence of surging. Thereby, in a centrifugal compressor, generation | occurrence | production of surging can be suppressed, after suppressing the fall of the compression efficiency which compresses air.

  The centrifugal compressor according to claim 2 of the present invention is the centrifugal compressor according to claim 1, wherein the moving member is formed with a wall surface extending in the flow direction and facing the inflow channel. It is characterized by.

  According to the above configuration, the moving member is formed with the wall surface extending in the air flow direction and facing the inflow channel. Thereby, the air which goes to an impeller flows along a wall surface, and flows in into an impeller. For this reason, for example, the member that changes the channel area of the inflow channel that guides air to the impeller is a thin plate member whose plate surface faces the axial direction, and the pressure loss of the air toward the impeller is reduced. The rise can be suppressed.

  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 minimizes the flow passage area and the downstream portion of the flow direction on the wall surface. However, the wall surface is inclined with respect to the axial direction so as to approach the rotation center line of the impeller.

  According to the above configuration, the wall surface is inclined with respect to the axial direction so that the downstream portion of the wall surface in the air flow direction approaches the rotation center line of the impeller. For this reason, the pressure loss of the air toward the impeller compared to the case where the wall surface is inclined with respect to the axial direction so that the downstream portion of the wall surface in the air flow direction is away from the rotation center line of the impeller. Can be suppressed.

  A centrifugal compressor according to a fourth aspect of the present invention is the centrifugal compressor according to the second or third aspect, wherein the moving member minimizes the flow path area, and the wall surface is downstream in the flow direction. An end on the side of the impeller is located on the downstream side in the flow direction with respect to the end on the upstream side in the flow direction.

  According to the above configuration, in the state in which the moving member minimizes the flow path area, the end on the downstream side in the flow direction on the wall surface is in the flow direction with respect to the upstream end in the flow direction on the impeller. Located downstream. In other words, the wall surface extends to the portion where the channel area is narrowed by the impeller. For this reason, an increase in the pressure loss of the air toward the impeller can be suppressed as compared with the case where the wall surface does not extend to the portion where the flow path area is narrowed by the impeller.

  A turbocharger according to a fifth aspect of the present invention is a turbine unit having a rotating turbine rotor and a rotational force transmitted from the turbine rotor to an impeller by a flow of exhaust gas discharged from the engine, and is supplied to the engine The centrifugal compressor of any one of Claims 1-4 which compresses the air to perform, It is characterized by the above-mentioned.

  According to the said structure, a turbocharger can be efficiently supplied to an engine by providing the centrifugal compressor of any one of Claims 1-4.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of surging can be suppressed, after suppressing the fall of the compression efficiency which compresses air.

It is sectional drawing which showed the centrifugal compressor which concerns on 1st Embodiment of this invention. It is sectional drawing which showed the centrifugal compressor which concerns on 1st Embodiment of this invention. It is the front view which showed the centrifugal compressor which concerns on 1st Embodiment of this invention. It is the front view which showed the centrifugal compressor which concerns on 1st Embodiment of this invention. It is sectional drawing which showed the centrifugal compressor which concerns on 1st Embodiment of this invention. It is drawing which showed the evaluation prediction result of the centrifugal compressor which concerns on 1st Embodiment of this invention, and the centrifugal compressor which concerns on a comparison form with the graph. It is the block diagram which showed the turbocharger which concerns on 1st Embodiment of this invention. It is sectional drawing which showed the centrifugal compressor which concerns on the comparison form with respect to the centrifugal compressor which concerns on 1st Embodiment of this invention. It is sectional drawing which showed the centrifugal compressor which concerns on 2nd Embodiment of this invention. It is sectional drawing which showed the centrifugal compressor which concerns on 2nd Embodiment of this invention. It is sectional drawing which showed the centrifugal compressor which concerns on 3rd Embodiment of this invention. It is sectional drawing which showed the centrifugal compressor which concerns on 3rd Embodiment of this invention. It is sectional drawing which showed the centrifugal compressor which concerns on 4th Embodiment of this invention. It is sectional drawing which showed the centrifugal compressor which concerns on 4th Embodiment of this invention. It is sectional drawing which showed the centrifugal compressor which concerns on 5th Embodiment of this invention. It is the front view which showed the centrifugal compressor which concerns on 5th Embodiment of this invention.

<First Embodiment>
An example of a centrifugal compressor and a 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 connection 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 housing 24, the centrifugal compressor 30 includes a housing 50, and the connection unit 40 includes a housing 44 that connects the housing 24 and the housing 50.

  Further, the turbocharger 10 includes a rotating shaft 42 that passes through the housing 24, the housing 44, and the housing 50, and the axial direction of the rotating shaft 42 (the direction of arrow E in the figure: hereinafter simply “axial direction”). ) From one end side (right side in the figure) to the other end side (left side in the figure), the housing 24, the housing 44, and the housing 50 are fixed to each other by a fixture (not shown) and are arranged in this order.

[Turbine unit]
As shown in FIG. 7, the turbine unit 20 includes a housing 24 and a turbine rotor 22. The housing 24 has a hollow inside, and the turbine rotor 22 is disposed inside the housing 24. The turbine rotor 22 includes a rotor shaft portion 28 fixed to a portion on one end side in the axial direction of the rotating shaft 42, and a plurality of turbine blades 26 extending from the rotor shaft portion 28.

  Further, in the housing 24, the exhaust gas flowing through the exhaust passage 12 is placed inside the housing 24 in a portion outside the radial direction of the rotation shaft 42 with respect to the turbine rotor 22 (arrow D direction in the drawing: hereinafter simply “radial direction”). A spiral spiral flow path 24A is formed to flow in. Further, in the housing 24, an exhaust passage 24 </ b> B that exhausts exhaust gas to the outside of the housing 24 and exhausts it to the exhaust passage 12 at a portion outside the axial direction (opposite to the housing 44 side) with respect to the turbine rotor 22. Is formed.

  In this configuration, exhaust gas (an example of fluid) that has flowed into the housing 24 from the spiral flow path 24 </ b> A flows between the adjacent turbine blades 26. The exhaust gas rotates the turbine rotor 22 by pushing a plurality of turbine blades 26. Further, the exhaust gas that has rotated the turbine rotor 22 is discharged from the discharge passage 24B. Thus, the turbine rotor 22 is a so-called radial turbine rotor.

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

  In addition, the housing 44 is circulated so that the engine oil supplied to the support portion 44A flows into the housing 44 (not shown), and the exhaust port (not shown) discharges the engine oil from the housing 44. And have.

  In this configuration, the engine oil that has flowed into the 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 housing 50 and an impeller 32. The housing 50 has a hollow inside, and the impeller 32 is disposed inside the housing 50. The impeller 32 includes a rotation shaft portion 34 fixed to a portion on the other end side in the axial direction of the rotation shaft 42, and a plurality of impeller blades 36 extending from the rotation shaft portion 34.

  In addition, an inflow passage 80 that guides air flowing through the intake passage 14 to the impeller 32 is formed in a portion of the housing 50 on the outer side in the axial direction with respect to the impeller 32 (on the side opposite to the housing 44 side). Further, a spiral spiral flow path 54 (so-called scroll flow path) that allows air to flow out of the housing 50 and to be discharged to the intake passage 14 is formed in a portion radially outside the impeller 32 in the housing 50. Has been.

  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 turbine blades 26 are pushed and rotated by the exhaust gas flowing into the housing 24 from the spiral flow path 24A. The rotational force of the turbine rotor 22 is transmitted to the impeller 32 via the rotation shaft 42. The exhaust gas that has rotated the turbine rotor 22 inside the housing 24 is discharged from the discharge passage 24B.

  The impeller 32 rotates when the rotational force of the turbine rotor 22 is transmitted via the rotating shaft 42. The rotating impeller 32 compresses the air guided from the intake passage 14 by the inflow channel 80. The rotating impeller 32 causes compressed air to flow in the radial direction. Further, the compressed air that has flowed in the radial direction 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.

  As shown in FIG. 1, the centrifugal compressor 30 includes an impeller 32, a housing 50 in which the impeller 32 is disposed, a wall member 70 as an example of a moving member, and a rocker that swings the wall member 70. The moving part 90 is provided.

[Impeller]
As described above, the impeller 32 includes the rotary shaft portion 34 fixed to the portion on the other end side in the axial direction of the rotary shaft 42, and the plurality of impeller blades 36 extending from the rotary shaft portion 34. Yes.

  The rotating shaft portion 34 gradually becomes thinner toward the outer side in the axial direction (on the opposite side to the housing 44 side: the left side in the drawing). Further, as shown in FIG. 3, each impeller blade 36 extends outward in the radial direction while being curved from the rotating shaft portion 34 when viewed from the axial direction. As shown in FIG. 1, each impeller blade 36 is connected to a distal end edge 36A extending in the radial direction at an outer portion in the axial direction and a radially outer end portion of the distal end edge 36A to be curved. However, it has a curved edge 36B extending inward in the axial direction (housing 44 side: right side in the figure). Further, each impeller blade 36 has a base end edge 36C that is connected to the end of the curved edge 36B and extends in the axial direction.

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

〔housing〕
The housing 50 includes an introduction passage 52 through which air flowing into the impeller 32 flows, a diffusion passage 56 (so-called diffuser passage) through which compressed air compressed by the impeller 32 flows, and a spiral flow through which compressed air is discharged into the intake passage 14. And a passage 54. Further, the housing 50 has a housing portion 57 that houses the impeller 32.

  As shown in FIG. 3, the diffusion channel 56 is formed so as to surround the impeller 32 when viewed from the axial direction. As shown in FIG. 1, the diffusion flow path 56 is compressed by the rotating impeller 32, and compressed air that has flowed radially outward from the base end edge 36 </ b> C of the impeller blade 36 flows therethrough. .

  As shown in FIG. 3, 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 compressed air is supplied to the intake passage 14 at one end of the spiral flow path 54. A discharge port 54A for discharging is formed. The flow passage cross section of the spiral flow passage 54 is substantially circular as shown in FIG. The spiral flow path 54 is configured to discharge the compressed air that has passed through the diffusion flow path 56 to the intake passage 14.

  The introduction path 52 is an outer portion in the axial direction with respect to the impeller 32 in the housing 50 and is formed inside a cylindrical introduction portion 60 extending in the axial direction. The introduction path 52 has a cylindrical shape with the rotation center line C1 of the impeller 32 as the center. Further, in the introduction path 52, an attachment portion 62 to which the wall member 70 is attached is provided on the inner side in the axial direction (housing 44 side: right side in the drawing) and on the outer side in the radial direction with respect to the impeller 32. Is formed.

A recess 64 having an opening in the axial direction is formed between the introduction wall 52 </ b> A constituting the introduction path 52 and the mounting portion 62.
The accommodating part 57 is formed between the introduction path 52 and the diffusion flow path 56 in the air flow direction, and a gap 58 is formed between the wall surface of the accommodating part 57 and the impeller 32.

(Wall member)
As shown in FIG. 1, the wall member 70 is disposed in the introduction path 52. Further, as shown in FIG. 3, six wall members 70 are provided side by side in the circumferential direction (rotation direction) of the impeller 32 when viewed from the axial direction. Further, each wall member 70 has an arc shape centered on the rotation axis of the impeller 32 as viewed in the axial direction.

  As shown in FIG. 1, each wall member 70 has a triangular main body portion 72 cut along a plane through which the rotation center line C <b> 1 of the impeller 32 passes. Further, each wall member 70 is connected to a portion on the inner side in the axial direction and on the outer side in the radial direction in the main body portion 72, and is extended to the extending portion 74 extending inward in the axial direction and the mounting portion 62. And a shaft portion 82 to be attached. The shaft portion 82 is provided at the distal end portion of the extending portion 74. A space surrounded by the main body portions 72 of the six wall members 70 serves as an inflow channel 80 that guides air to the impeller 32. The inflow channel 80 has a circular shape when viewed from the axial direction.

  Furthermore, a wall surface 72 </ b> A that faces the inflow channel 80 is formed in the main body 72 of the wall member 70. The wall surface 72 </ b> A extends in the flow direction of air guided to the impeller 32. And the length (F1 in the figure) of the wall surface 72A in the cut surface cut by the plane through which the rotation center line C1 of the impeller 32 passes is larger than the length in the radial direction of the tip edge 36A of the impeller blade 36 (F2 in the figure). Have been long.

  Further, the shaft portion 82 is provided in an inner portion in the axial direction of the extending portion 74. As shown in FIG. 3, the shaft portion 82 is disposed in a central portion of the wall member 70 in the circumferential direction of the impeller 32, and extends in a tangential direction in contact with an arc constituting the main body portion 72. .

  In this configuration, the movement range of each wall member 70 is restricted by a restriction member (not shown), and the wall member 70 swings about the shaft portion 82. Each wall member 70 has a minimum position (see FIGS. 1 and 3) that minimizes the channel area of the inflow channel 80 and a maximum position (FIG. 2) that maximizes the channel area of the inflow channel 80. , See FIG. 4).

  In addition, the area of the part where the cut surface becomes the smallest in the cut surface obtained by cutting the inflow channel 80 in the direction orthogonal to the axial direction is the channel area. When the region surrounded by the wall member 70 (K2 in FIG. 1) is narrower than the region (K1 in FIG. 2) surrounding the tip edge 36A of the impeller blade 36 by the housing 50, the flow path area is This is the area of the region surrounded by the wall member 70. On the other hand, when the region surrounded by the wall member 70 (K3 in FIG. 2) is equal to or wider than the region (K1 in FIG. 2) surrounding the tip edge 36A of the impeller blade 36 by the housing 50, the flow path The area is the area of the region surrounding the tip edge 36 </ b> A of the impeller blade 36 by the housing 50.

  In the state where the wall member 70 is disposed at the maximum position, the area of the region surrounded by the wall member 70 is larger than the area of the region surrounding the tip edge 36 </ b> A of the impeller blade 36 by the housing 50. Further, the area of the region surrounded by the wall member 70 in a state where the wall member 70 is disposed at the minimum position is smaller than the area of the region surrounding the tip edge 36 </ b> A of the impeller blade 36 by the housing 50.

  Furthermore, in the state where the wall member 70 is disposed at the minimum position, the area of the region surrounded by the wall member 70 (flow path area, see K2 in FIG. 1) is the area of the entrance of the impeller 32 (K4 in FIG. 1). Compared to the reference). Here, the area of the entrance of the impeller 32 is an area of a circle drawn by the tip edge 36 </ b> A of the impeller blade 36 as viewed from the axial direction by rotating the impeller 32.

  Further, in the state where the wall member 70 is disposed at the minimum position, the portion of the wall surface 72A on the downstream side in the air flow direction has a rotation center line C1 of the impeller 32 as compared with the portion on the upstream side in the air flow direction. The wall surface 72A is inclined with respect to the axial direction (see FIG. 1).

  Furthermore, in the state where the wall member 70 is disposed at the minimum position, an end T1 on the downstream side in the air flow direction on the wall surface 72A is an end on the upstream side in the air flow direction in the rotation shaft portion 34 of the impeller 32. It is located on the inner side in the axial direction (downstream side in the air flow direction) with respect to the portion T2. In the wall surface 72 </ b> A, the downstream end T <b> 1 in the air flow direction is a portion located on the innermost side in the radial direction in a state where the wall member 70 is disposed at the minimum position. That is, the wall surface 72A of the wall member 70 is a range from the outer end in the axial direction of the wall member 70 to the end portion T1 in a state where the wall member 70 is disposed at the minimum position.

[Oscillating part]
As shown in FIG. 1, the swinging part 90 includes a link 92 having one end connected to the shaft part 82, a ring member 94 to which the other ends of all the links 92 are connected, and one end to the ring member 94. A connected rod 96 and an actuator 98 for moving the rod 96 are provided.

  One end of the link 92 is attached to the shaft portion 82 and extends outward from the shaft portion 82 in the radial direction.

  As shown in FIG. 3, the ring member 94 is disposed in a concave portion 64 (see FIG. 1) formed in the housing 50 so as to surround the wall member 70 disposed in the minimum position when viewed from the axial direction. ing. The other end of the link 92 is rotatably attached to a long hole (not shown) formed in the ring member 94.

  As shown in FIG. 1, the rod 96 extends in the axial direction, and the axially inner end of the rod 96 is attached to the ring member 94 (see FIG. 3).

  The actuator 98 is attached to the outer end of the rod 96 in the axial direction, and moves the rod 96 in the axial direction under the control of a control unit (not shown) described later.

  In this configuration, the actuator 98 moves the rod 96 in the axial direction, so that the ring member 94 moves in the axial direction. As a result, each of the links 92 swings about the respective shaft portion 82, so that each wall member 70 swings. That is, each wall member 70 is configured to move in the radial direction.

  The swinging wall member 70 is at the minimum position (see FIGS. 1 and 3), the maximum position (see FIGS. 2 and 4), and an intermediate position between the minimum position and the maximum position (see FIG. 5). It is supposed to move.

(Function)
Next, the operation of the centrifugal compressor 30 will be described in comparison with the operation of the centrifugal compressor 330 according to the comparative form. Further, an example of surging generated in the centrifugal compressors 30 and 330 and control of the centrifugal compressor 30 with respect to the actuator 98 will be described.

[Operation of centrifugal compressor]
First, with respect to the configuration of the centrifugal compressor 330 according to the comparative embodiment, portions different from the configuration of the centrifugal compressor 30 will be mainly described. Further, the operation of the centrifugal compressor 330 will be mainly described with respect to a portion different from the operation of the centrifugal compressor 30.

  As shown in FIG. 8, the centrifugal compressor 330 does not include a wall member and a swinging portion.

An inflow channel 380 that guides air to the impeller 32 is formed inside the introduction portion 360 of the housing 350 provided in the centrifugal compressor 330. The inflow channel 380 has a funnel shape with a diameter reduced toward the inner side in the axial direction.

  The flow passage area of the inflow passage 380 is the area of the region (K5 in FIG. 8) surrounding the tip edge 36A of the impeller blade 36 by the housing 350, and the tip edge 36A of the impeller blade 36 is changed by the housing 50 according to the embodiment. This is the same as the area of the surrounding region (K1 in FIG. 2).

  Next, the operation of the centrifugal compressors 30 and 330 when the flow rate of the compressed air discharged from the centrifugal compressor 330 is small will be described.

  When the flow rate of the compressed air discharged from the centrifugal compressor 330 is small, the pressure ratio of the centrifugal compressor 330 becomes larger than when the flow rate of the compressed air discharged from the centrifugal compressor 330 is large. Yes. The pressure ratio is a ratio P2 / P1 between the pressure P2 of the air flowing out from the impeller 32 of the centrifugal compressor 330 and the pressure P1 of the air flowing into the impeller 32.

  As shown in FIG. 8, the rotating impeller 32 flows through the inflow passage 380 along the axial direction toward the impeller 32 and compresses the air flowing in from the tip edge 36 </ b> A side of the impeller blade 36 (arrow L <b> 1). The rotating impeller 32 causes the compressed air to flow from the base end edge 36 </ b> C of the impeller blade 36 to the diffusion channel 56 outside in the radial direction.

  Further, the air flowing from the base end edge 36C of the impeller blade 36 to the radially outer diffusion flow path 56 is folded back in the opposite direction to the air flowing to the spiral flow path 54 (arrow L2) and the impeller blade 36 and the housing. 50 (divided) into air (arrow L3) flowing to the inflow channel 380 side through the gap 58 with respect to 50.

  Air compressed by the rotating impeller 32 and flowing through the diffusion flow path 56 toward the spiral flow path 54 (hereinafter referred to as “compressed air”) passes through the intake passage 14 and is supplied to the engine as compressed air for combustion. .

  When the flow rate of the compressed air discharged from the centrifugal compressor 330 is large, the pressure ratio of the centrifugal compressor 330 is smaller than when the flow rate of the compressed air discharged from the centrifugal compressor 330 is small. Become. For this reason, the backflow of the air which flowed from the base end edge 36C of the impeller blades 36 to the radially outer diffusion flow path 56 is suppressed.

  In addition, about the effect | action of the centrifugal compressor 30 in which the wall member 70 is arrange | positioned in the maximum position, it is the same as that of the centrifugal compressor 330 (refer FIG. 2).

  Next, the operation of the centrifugal compressor 30 when the flow rate of the compressed air discharged from the centrifugal compressor 30 in which the wall member 70 is disposed at the minimum position is small will be described.

  When the flow rate of compressed air discharged from the centrifugal compressor 30 is small, the pressure ratio of the centrifugal compressor 30 becomes larger than when the flow rate of compressed air discharged from the centrifugal compressor 30 is large. Yes.

  As shown in FIG. 1, the rotating impeller 32 flows in the inflow passage 80 along the axial direction toward the impeller 32, and compresses air (arrow M <b> 1) flowing in from the tip edge 36 </ b> A side of the impeller blade 36. The rotating impeller 32 causes the compressed air to flow from the base end edge 36 </ b> C of the impeller blade 36 to the diffusion channel 56 outside in the radial direction.

  Furthermore, the air that has flowed from the base end edge 36C of the impeller blade 36 to the radially outer diffusion flow path 56 is folded back in the opposite direction to the air (arrow M2) that flows toward the spiral flow path 54, and the impeller blade 36 and the housing. 50 (divided) into the air (arrow M3) flowing through the gap 58 to the inflow channel 80 side.

  Here, the channel area of the inflow channel 80 of the centrifugal compressor 30 in which the wall member 70 is disposed at the minimum position is smaller than the channel area of the centrifugal compressor 330.

  For this reason, the pressure of the air flowing to the impeller 32 side of the centrifugal compressor 30 in which the wall member 70 is disposed at the minimum position is higher than the pressure of the air flowing into the impeller 32 of the centrifugal compressor 330. Then, the pressure ratio of the centrifugal compressor 30 in which the wall member 70 is disposed at the minimum position is higher than the pressure ratio of the centrifugal compressor 330.

  Thereby, the amount of air (arrow M3) that flows back to the inflow channel 80 side is compared with the amount of air (arrow L3) that flows back to the inflow channels 80 and 380 when the centrifugal compressor 330 is used. And less.

[Surging]
Next, surging that occurs in the centrifugal compressors 30 and 330 will be described.

  Surging is an unstable phenomenon in which vibrations and the like occur in the centrifugal compressors 30 and 330. With regard to surging, surging occurs when a vibration meter is attached to the housings 50 and 350 and the amplitude reaches a predetermined threshold. Can be determined.

  When the centrifugal compressor 30 in which the wall member 70 is disposed at the minimum position is used, the surging limit when the centrifugal compressor 330 is used will be described.

  The vertical axis of the graph shown in FIG. 6 indicates the pressure ratio with the case where the centrifugal compressors 30 and 330 are used, and the horizontal axis indicates the flow rate of compressed air discharged from the centrifugal compressors 30 and 330 [g / sec]. Is shown. Note that the graph shown in FIG. 6 is not a graph based on an actual machine test, but a prediction graph created based on knowledge based on similar test results.

  A solid line G1 in the graph shown in FIG. 6 indicates 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 in which the wall member 70 is disposed at the minimum position is changed. The relationship between the flow rate and the pressure ratio is shown.

  On the other hand, the alternate long and short dash line J1 indicates the flow rate of the compressed air when the rotational speed of the impeller 32 is the same as that of the solid line G1 and the flow rate of the compressed air discharged from the centrifugal compressor 330 is changed. And the pressure ratio.

  Then, the flow rate of compressed air was gradually reduced to predict the flow rate of compressed air and the pressure ratio at which surging occurs. For the centrifugal compressor 30 in which the wall member 70 is disposed at the minimum position, surging occurs at the point g1, and for the centrifugal compressor 330, surging occurs at the point j1.

  A solid line G2 indicates a case where the centrifugal compressor 30 in which the wall member 70 is disposed at the minimum position is used and the rotational speed is increased as compared with the solid line G1. In the solid line G2, surging occurs at the point g2 where the flow rate of compressed air is the smallest. On the other hand, an alternate long and short dash line J2 indicates a case where the rotational speed of the impeller 32 is set to the same rotational speed as that of the solid line G2 and the centrifugal compressor 330 is used. In the alternate long and short dash line J2, surging occurs at the point j2 where the flow rate of the compressed air is the smallest.

  In addition, examinations similar to those for the solid lines G1 and G2 and the alternate long and short dash lines J1 and J2 were performed at other rotational speeds. When the centrifugal compressor 30 in which the wall member 70 is disposed at the minimum position is used, the flow rate and pressure ratio of compressed air that generates surging are predicted when the centrifugal compressor 330 is used.

  A broken line H1 in the graph is a surging limit line H1 (hereinafter, “limit line H1”) when the centrifugal compressor 30 in which the wall member 70 is disposed at the minimum position is used. Further, a broken line H2 in the graph is a surging limit line H2 (hereinafter, “limit line H2”) when the centrifugal compressor 330 is used.

  In the centrifugal compressor 30 in which the wall member 70 is disposed at the minimum position, surging does not occur in the area on the right side (the side with the larger flow rate) than the limit line H1 in the graph. In the centrifugal compressor 330, surging does not occur in the area on the right side (the larger flow rate side) of the limit line H2 in the graph.

  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 is reduced, as described above, the air flowing from the base end edge 36C of the impeller blade 36 to the radially outer diffusion flow path 56 is in the opposite direction to the air flowing to the spiral flow path 54 side. It divides into the air which turns and flows (refer FIG.1, FIG.2, FIG.8). Surging occurs due to the backflow of air.

  Here, when the limit line H1 and the limit line H2 in the graph shown in FIG. 6 are compared, the limit line H1 is located on the left side (the side where the air flow rate is small) as compared to the limit line H2. Accordingly, when the flow rate of the compressed air is small, in the centrifugal compressor 30 in which the wall member 70 is disposed at the minimum position, occurrence of surging is suppressed as compared with the case where the centrifugal compressor 330 is used. I understand.

  This is because when the centrifugal compressor 30 in which the wall member 70 is disposed at the minimum position is used, the amount of air that flows backward (arrow M3) is equal to the amount of air that flows backward (arrow L3) when the centrifugal compressor 330 is used. This is because it is smaller than the amount of).

[Example of actuator control]
Next, an example of control on the actuator 98 by the control unit will be described. Note that the control unit is a control unit for an automobile including the centrifugal compressor 30 and controls each device of the automobile.

  The automobile is provided with a map that defines the relationship between the pressure ratio of the centrifugal compressor 30, the flow rate of the compressed air discharged from the centrifugal compressor 30, and the position where the wall member 70 is disposed. When the pressure ratio and the flow rate are determined by this map, it is determined whether the wall member 70 is disposed at the minimum position, the maximum position, or the intermediate position between the minimum position and the maximum position. It is like that.

  Specifically, with regard to the centrifugal compressor 30, when the flow rate of the compressed air discharged from the centrifugal compressor 30 is large, if the wall member 70 is disposed at the minimum position, the compression efficiency for compressing air decreases. End up. Therefore, it is determined whether the wall member 70 is disposed at the minimum position, the maximum position, or the intermediate position from the viewpoint of suppressing occurrence of surging and suppressing a decrease in compression efficiency for compressing air. It has become.

  And a control part receives the information of the flow volume of compressed air from the air flow meter of an engine, and also receives the information of pressure ratio from the boost meter of an intake manifold of an engine. Then, the control unit controls the actuator 98 based on the received compressed air flow rate information, pressure ratio information, and the aforementioned map, and moves the wall member 70 to a suitable position.

(Summary)
As described above, the flow passage area of the inflow flow passage 80 of the centrifugal compressor 30 in which the wall member 70 is disposed at the minimum position is smaller than the flow passage area of the centrifugal compressor 330. Furthermore, in the state where the wall member 70 is disposed at the minimum position, the area of the region surrounded by the wall member 70 (flow path area, see K2 in FIG. 1) is the area of the entrance of the impeller 32 (K4 in FIG. 1). Compared to (see). Thus, in the centrifugal compressor 30 in a state where the flow rate of the compressed air discharged from the centrifugal compressor 30 is small and the wall member 70 is disposed at the minimum position, the air that flows backward to the inflow channel 80 side. The amount of can be reduced. In other words, the occurrence of surging can be suppressed.

  Further, from the viewpoint of suppressing the occurrence of surging and suppressing the decrease in compression efficiency for compressing air, the wall member 70 is moved to a suitable position to suppress the decrease in compression efficiency for compressing air. Thus, occurrence of surging can be suppressed.

  The wall member 70 is formed with a wall surface 72 </ b> A that extends in the air flow direction and faces the inflow channel 80. As a result, the air traveling toward the impeller 32 flows along the wall surface 72 </ b> A and flows into the impeller 32 from the tip edge 36 </ b> A side of the impeller blade 36. For this reason, for example, the member that changes the flow passage area of the inflow passage 80 that guides air to the impeller 32 is a thin plate member whose plate surface faces the axial direction. An increase in pressure loss can be suppressed.

  Further, in the state where the wall member 70 is disposed at the minimum position, the portion of the wall surface 72A on the downstream side in the air flow direction has a rotation center line C1 of the impeller 32 as compared with the portion on the upstream side in the air flow direction. The wall surface 72A is inclined with respect to the axial direction. For this reason, the pressure loss of the air toward the impeller blades 36 is smaller than that in the case where the wall surface is inclined so that the downstream portion of the wall surface 72A in the air flow direction moves away from the rotation center line C1 of the impeller 32. Can be suppressed.

  Further, in the state where the wall member 70 is disposed at the minimum position, an end T1 on the downstream side in the air flow direction on the wall surface 72A is an upstream end in the air flow direction on the rotating shaft portion 34 of the impeller 32. It is located on the inner side in the axial direction with respect to the portion T2. In other words, the wall surface 72 </ b> A of the wall member 70 extends to a portion where the flow passage area is narrowed by the rotation shaft portion 34. For this reason, as compared with the case where the wall surface 72A of the wall member 70 does not extend to the portion where the flow path area is narrowed by the rotating shaft portion 34, the increase in the pressure loss of the air toward the impeller blades 36 can be suppressed. it can.

  Moreover, generation | occurrence | production of surging can be effectively suppressed by the raise of a pressure loss being suppressed.

  In addition, the turbocharger 10 includes the centrifugal compressor 30 in which the occurrence of surging 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 2nd Embodiment, a different part from 1st Embodiment is mainly demonstrated.

  As shown in FIG. 9, the centrifugal compressor 130 according to the second embodiment includes a cylindrical cylindrical member 132 and a biasing member 134 that biases the cylindrical member 132 against the main body 72 of the wall member 70. I have.

  The cylindrical member 132 has a cylindrical shape centered on the rotation center line C <b> 1 of the impeller 32, and is disposed between the shaft portion 82 and the impeller 32 in the radial direction.

  Specifically, the mounting portion 62 of the housing 50 is formed with a recess 62A that is open on the outside in the axial direction. A cylindrical member 132 is disposed in the recess 62A.

  The urging member 134 is a compression spring and is disposed between the proximal end portion of the cylindrical member 132 and the bottom of the recess 62A. The urging member 134 urges the cylindrical member 132 toward the main body 72 so that the tip of the cylindrical member 132 contacts the main body 72 of the wall member 70 from the outside in the axial direction. .

  In this configuration, as shown in FIG. 9, the cylindrical member 132 that comes into contact with the main body 72 of the wall member 70 at the tip end portion is accommodated in the recess 62 </ b> A in a state where the wall member 70 is disposed at the minimum position. Yes.

  On the other hand, as shown in FIG. 10, the cylindrical member 132 maintains contact with the main body portion 72 by the urging force of the urging member 134 in a state where the wall member 70 is disposed at the maximum position. , And protrudes from the recess 62A. The air flowing along the wall surface 72 </ b> A of the wall member 70 does not enter the space between the main body portion 72 of the wall member 70 and the attachment portion 62.

<Third Embodiment>
Next, an example of a centrifugal compressor and a turbocharger according to a third embodiment of the present invention will be described with reference to FIGS. In addition, about 3rd Embodiment, a different part from 1st Embodiment is mainly demonstrated.

  As shown in FIG. 11, the mounting portion 162 of the centrifugal compressor 160 according to the third embodiment is formed with a convex portion 164 that protrudes toward the wall member 170. Further, the main body 172 of the wall member 170 of the centrifugal compressor 160 is formed with a concave portion 174 in which the convex portion 164 is accommodated in a state of being disposed at the minimum position. The wall member 170 is an example of a moving member.

  When viewed from the axial direction of the shaft portion 82, the peripheral surface of the convex portion 164 and the peripheral surface of the concave portion 174 have an arc shape centered on the shaft portion 82. And the peripheral surface of the recessed part 174 of the wall member 170 arrange | positioned in the minimum position and the peripheral surface of the convex part 164 come into contact.

  In this configuration, as shown in FIG. 11, the convex portion 164 formed on the attachment portion 162 is accommodated in the concave portion 174 of the main body portion 172 of the wall member 170 in a state where the wall member 170 is disposed at the minimum position. Has been.

  On the other hand, as shown in FIG. 12, a part of the convex portion 164 of the attachment portion 162 faces the inflow channel 80 in a state where the wall member 170 is disposed at the maximum position. . Thereby, in the state where the wall member 170 is disposed at the maximum position, air enters the space between the main body portion 172 and the mounting portion 162 of the wall member 170 as compared with the configuration of the first embodiment. It has come to suppress.

<Fourth embodiment>
Next, an example of a centrifugal compressor and a turbocharger according to a fourth embodiment of the present invention will be described with reference to FIGS. In addition, about 4th Embodiment, a different part from 1st Embodiment is mainly demonstrated.

  As shown in FIG. 13, a through hole 194 that penetrates the inside of the attachment portion 192 is formed in the attachment portion 192 of the centrifugal compressor 190 according to the fourth embodiment. Further, the wall member 200 of the centrifugal compressor 190 is formed with a through hole 196 that penetrates the inside of the main body 202 of the wall member 200. The wall member 200 is an example of a moving member.

  One opening of the through hole 194 formed in the attachment portion 192 faces the curved edge 36B of the impeller blade 36, and the other opening of the through hole 194 faces the main body portion 202 of the wall member 200.

  In addition, one opening of the through hole 196 formed in the main body 202 is opposed to the other opening of the through hole 194 of the mounting portion 192 in a state where the wall member 170 is disposed at the minimum position. The other opening of 196 is formed in the wall surface 202 </ b> A so as to face the inflow channel 80.

  In this configuration, when the flow rate of the compressed air discharged from the centrifugal compressor 190 is small and the wall member 200 is disposed at the minimum position, as shown in FIG. Part of the air flowing toward the path 80 enters the through hole 194 (see the arrow in the figure). The air that has entered the through hole 194 is discharged to the inflow channel 80 through the through hole 194 and the through hole 196.

  The air discharged to the inflow channel 80 merges with the air from the intake passage 14 through the inflow channel 80 toward the impeller 32. As a result, the amount of air flowing in from the tip edge 36 </ b> A side of the impeller blade 36 increases by the amount of the circulating flow passing through the through hole 196. For this reason, generation | occurrence | production of surging is suppressed because the flow velocity which flows in from the front end edge 36A side of the impeller blade | wing 36 increases.

  Further, as shown in FIG. 14, one opening of the through hole 196 formed in the main body portion 202 in the state where the wall member 200 is disposed at the maximum position is the other of the through hole 194 of the mounting portion 192. Does not face the opening.

<Fifth Embodiment>
Next, an example of a centrifugal compressor and a turbocharger according to a fifth embodiment of the present invention will be described with reference to FIGS. In addition, about 5th Embodiment, a different part from 1st Embodiment is mainly demonstrated.

(Constitution)
As shown in FIGS. 15 and 16, one wall member 70 among the wall members 70 provided in the centrifugal compressor 220 according to the fifth embodiment has a protruding portion 242 that protrudes into the inflow channel 80. Is formed. The protruding portion 242 has a plate shape, and the plate surface of the protruding portion 242 faces the circumferential direction of the rotating impeller 32. Further, the protruding portion 242 extends in the axial direction from one end to the other end of the wall surface 72A of the wall member 70 in the axial direction. Further, the protruding end 242A of the protruding portion 242 is along the rotation center line C1 of the impeller 32 in a state where the wall member 70 is disposed at the minimum position.

(Function)
Next, the operation of the centrifugal compressor 220 in a state where the flow rate of the compressed air discharged from the centrifugal compressor 220 is small and the wall member 70 is disposed at the minimum position will be described.

  As shown in FIG. 15, the rotating impeller 32 flows in the inflow channel 80 along the axial direction toward the impeller 32, compresses the air (arrow R <b> 1) flowing in from the tip edge 36 </ b> A side of the impeller blade 36, and The air flows from the base end edge 36C of the blade 36 to the diffusion channel 56 outside in the radial direction.

  The air that has flowed from the base end edge 36C of the impeller blade 36 to the radially outer diffusion flow path 56 is folded back in the opposite direction to the air flowing to the spiral flow path 54 (arrow R2), and the impeller blade 36 and the housing 50 Air (arrow R3) flowing through the gap 58 to the inflow channel 80 side (separated).

  Further, the air that has flowed back to the inflow channel 80 side flows spirally along the wall surface 72A of the wall member 70 as shown in FIG. 16 (arrow R4).

  Here, a protrusion 242 is formed on the wall surface 72 </ b> A of one wall member 70. For this reason, the air flowing spirally along the wall surface 72A of the wall member 70 hits (guides) the protrusion 242 and flows toward the rotation center of the impeller 32 as viewed from the axial direction (arrow M5).

  And the air which flowed to the rotation center side of the impeller 32 presses (pressurizes) the air (arrow R6) flowing to the impeller 32 side along the inflow channel 80 in the axial direction. As a result, the air flowing toward the impeller 32 is pressed (approached) to a portion of the inflow channel 80 opposite to the protruding portion 242. For this reason, the pressure of the air flowing into the impeller 32 increases, and the pressure ratio of the centrifugal compressor 220 decreases. In the centrifugal compressor 220, occurrence of surging is suppressed.

  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-described embodiment, the wall member 70 is formed with the wall surface 72A that extends in the air flow direction and faces the inflow channel 80, but the wall surface 72A that extends in the air flow direction is formed on the wall member. It does not have to be. However, in this case, the action that occurs when the wall surface 72A is formed on the wall member 70 does not occur.

  Further, in the above-described embodiment, the wall surface 72A in the state where the wall member 70 is disposed at the minimum position is such that the downstream portion of the wall surface 72A in the air flow direction is compared with the upstream portion of the air flow direction. Thus, it is inclined with respect to the axial direction so as to approach the rotation center line C1 of the impeller 32. However, the wall surface does not have to be inclined in this way. In this case, the action caused by inclining the wall surface 72A in this way does not occur.

  In the above-described embodiment, the wall surface 72A of the wall member 70 extends to a portion where the flow passage area is narrowed by the rotation shaft portion 34. The wall surface 72A of the member 70 may not extend. However, in this case, the action caused by the wall surface 72A of the wall member 70 extending to the portion where the flow path area is narrowed by the rotating shaft portion 34 does not occur.

  Moreover, in the said embodiment, although the wall member 70 is provided six along with the circumferential direction of the impeller 32 seeing from an axial direction, the number other than six may be sufficient.

  Further, although not particularly described in the above embodiment, there may be a plurality of stop positions of the wall member 70 between the minimum position of the wall member 70 and the maximum position of the wall member 70.

  Moreover, in the said embodiment, the wall member 70 moved to radial direction by rocking | fluctuating the wall member 70 centering on the axial part 82 extended in the tangential direction which contact | connects the circular arc of the main-body part 72 seeing from an axial direction. However, for example, the wall member may be moved in the radial direction by sliding the wall member in the radial direction or by swinging the wall member about the shaft portion along the axial direction.

DESCRIPTION OF SYMBOLS 10 Turbocharger 20 Turbine unit 22 Turbine rotor 30 Centrifugal compressor 70 Wall member (an example of a moving member)
72A Wall surface 80 Inflow channel 130 Centrifugal compressor 160 Centrifugal compressor 170 Wall member (an example of a moving member)
190 Centrifugal compressor 200 Wall member (an example of a moving member)
202A Wall 220 centrifugal compressor

Claims (5)

An impeller that rotates about an axis, compresses air flowing in from the axial direction, and flows in the radial direction;
A moving member that is disposed upstream of the impeller in the air flow direction, moves in the radial direction, and changes a flow passage area of an inflow passage that guides air to the impeller; and
In the state where the moving member minimizes the flow passage area, the flow passage area is smaller than the entrance area of the impeller.   The centrifugal compressor according to claim 1, wherein the moving member is formed with a wall surface extending in the flow direction and facing the inflow channel.   The wall surface is inclined with respect to the axial direction so that the downstream portion of the flow direction in the wall surface approaches the rotation center line of the impeller with the moving member having the flow path area minimized. The centrifugal compressor according to claim 2.   In the state in which the moving member minimizes the flow path area, the end on the downstream side in the flow direction on the wall surface is in the flow direction with respect to the end on the upstream side in the flow direction in the impeller. The centrifugal compressor according to claim 2, which is located downstream of the compressor. A turbine unit having a turbine rotor that rotates by the force of exhaust gas discharged from the engine;
The centrifugal compressor according to any one of claims 1 to 4, wherein a rotational force is transmitted from the turbine rotor to an impeller, and compresses air supplied to the engine.
Turbocharger with