Volute and Centrifugal Compressor

Abstract

For the volute of a centrifugal compressor, when the flow path width of the diffuser flow path along the axial direction of the centrifugal compressor is defined as Ta, and the shortest distance from the connection position (i.e., the starting end position) of the inner peripheral surface of the scroll part forming the scroll flow path to the hub side flow path surface of the diffuser flow path to the imaginary circular arc tangent to the end position (i.e., the terminal position) on the opposite side of the inner peripheral surface from the starting end position is defined as Tb, and for the angular position around the scroll center in the scroll flow path, when the confluence position of the start and end of the winding of the scroll flow path is set to 60 degrees and the angular position is defined such that the angle gradually increases toward the downstream side of the scroll flow path, in the range of the angular position from 180 degrees to 360 degrees, the relationship Tb / Ta≥1.0 is satisfied.

Description

Technical Field

[0001] The present disclosure relates to a volute and a centrifugal compressor including the volute. Background Art

[0002] In a centrifugal compressor used in a compression section of a vehicle or marine turbocharger, etc., the rotation of an impeller is used to provide kinetic energy to a fluid and discharge the fluid radially outward, and the centrifugal force is used to increase the fluid pressure. For such a centrifugal compressor, high pressure ratio and high efficiency are required in a wide operating range, and various efforts have been made for this.

[0003] Generally, a centrifugal compressor includes a volute that houses the impeller in a rotatable manner. The volute includes a scroll portion that forms a spiral scroll flow path and a diffuser portion that forms a diffuser flow path for guiding the fluid that has passed through the impeller to the scroll flow path (for example, Patent Document 1).

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: International Publication No. 2018 / 179112 Summary of the Invention

[0007] Technical Problem to be Solved by the Invention

[0008] Figure 14 And Figure 15 are explanatory diagrams for explaining the shapes of the diffuser portion 04 and the scroll portion 05 of the volute 03 of the centrifugal compressor of the comparative example. As Figure 14 And Figure 15 show, the scroll portion 05 has an inner peripheral surface 051 that defines the scroll flow path 050. The inner peripheral surface 051 is formed in an arc shape that extends from the connection position with the hub-side flow path surface 042 of the diffuser flow path 040, that is, the start end position P01, in one direction UD side and extends to the end position on the side opposite to the start end position P01, that is, the terminal position P02. The volute 03 has a diffuser outlet flange portion 054, and the diffuser outlet flange portion 054 includes the inner peripheral surface 051 including the terminal position P02 and the shroud-side flow path surface 041 of the diffuser flow path 040. Since the fluid flowing into the scroll flow path 050 from the outlet of the diffuser flow path 040 has a swirling velocity component, a rotating flow SF that flows along the inner peripheral surface 051 toward the one direction UD side is formed. In such a scroll flow path 050, the rotating flow SF flowing along the inner peripheral surface 051 and the outlet flow DF of the diffuser flow path flowing into the scroll flow path 050 from the outlet of the diffuser flow path 040 converge on the downstream side of the diffuser outlet flange portion 054.

[0009] In the opinion of the present inventors, as Figure 14As shown, if the thickness T of the diffuser outlet flange portion 054, that is, the length T along the axial direction between the downstream end 043 of the shroud side flow surface 041 of the diffuser flow path 040 and the terminal position P02, is large, a low flow velocity region WA called wake may be generated at a position immediately downstream of the diffuser outlet flange portion 054 corresponding to the thickness T of the diffuser outlet flange portion 054. If the wake is large, the wake loss of the rotating flow SF increases, and thus the efficiency of the centrifugal compressor may decrease.

[0010] If, in order to suppress the wake loss, as Figure 15 shown, the thickness T of the diffuser outlet flange portion 054 is small, the difference in the flow angle between the rotating flow SF and the outlet flow DF of the diffuser flow path 040 becomes large. Therefore, due to the interference between the rotating flow SF and the outlet flow DF, at least a part of the outlet flow DF is blocked. If at least a part of the outlet flow DF is blocked, the resistance of the fluid flowing through the diffuser flow path 040 increases, and diffuser stall may be induced. If diffuser stall is induced, the efficiency of the centrifugal compressor drops extremely, and surge caused by the diffuser stall is induced, and the operating range of the centrifugal compressor may be reduced. In addition, if the thickness T of the diffuser outlet flange portion 054 is too small, a shortage of the diffuser outlet flange portion 054 may occur, which is not preferable.

[0011] In view of the above situation, an object of at least one embodiment of the present disclosure is to provide a volute and a centrifugal compressor capable of suppressing a decrease in the efficiency of the centrifugal compressor and a reduction in the operating range.

[0012] Technical solutions for solving technical problems

[0013] The volute of the present disclosure is a volute of a centrifugal compressor and includes:

[0014] a diffuser portion that forms the diffuser flow path of the centrifugal compressor; and

[0015] a scroll portion that forms the scroll flow path of the centrifugal compressor,

[0016] When the flow path width of the diffuser flow path along the axial direction of the centrifugal compressor is defined as Ta, and the shortest distance from the connection position (i.e., the start position) of the inner peripheral surface of the scroll portion to the hub side flow surface of the diffuser flow path to the imaginary circular arc tangent to the end position (i.e., the terminal position) on the opposite side of the start position on the inner peripheral surface is defined as Tb, and for the angular position around the scroll center in the scroll flow path, the angular position is defined such that the convergence position of the start and end of the winding of the scroll flow path is 60 degrees and the angle gradually increases toward the downstream side of the scroll flow path.

[0017] In the range where the angular position is from 180 degrees to 360 degrees, the relationship of Tb / Ta≥1.0 is satisfied.

[0018] The centrifugal compressor of the present disclosure includes the volute.

[0019] Effects of the Invention

[0020] According to at least one embodiment of the present disclosure, a volute and a centrifugal compressor are provided that can suppress a decrease in the efficiency of the centrifugal compressor and a reduction in the operating range. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is an explanatory diagram for explaining the structure of a turbocharger including a centrifugal compressor according to one embodiment.

[0022] Figure 2 It is a schematic cross-sectional view on the compressor side of a turbocharger including a centrifugal compressor according to one embodiment, and is a schematic cross-sectional view including the axis of the centrifugal compressor.

[0023] Figure 3 It is an explanatory diagram for explaining the shapes of the diffuser portion and the scroll portion of a volute according to one embodiment.

[0024] Figure 4 It is an explanatory diagram for explaining the shapes of the diffuser portion and the scroll portion of a volute according to one embodiment.

[0025] Figure 5 It is an explanatory diagram for explaining the shapes of the diffuser portion and the scroll portion of a volute according to one embodiment.

[0026] Figure 6 It is an explanatory diagram for explaining the shapes of the diffuser portion and the scroll portion of a volute according to one embodiment.

[0027] Figure 7 It is a schematic diagram of a scroll flow path in an axial view of a centrifugal compressor according to one embodiment.

[0028] Figure 8 It is an explanatory diagram for explaining a volute according to one embodiment, and is an explanatory diagram showing the relationship between the angular position and the distance ratio Tb / Ta in the scroll flow path.

[0029] Figure 9 It is an explanatory diagram for explaining the shapes of the diffuser portion and the scroll portion of a volute according to one embodiment.

[0030] Figure 10 It is an explanatory diagram for explaining a volute according to one embodiment, and is an explanatory diagram showing the relationship between the angular position and the crossing angle α in the scroll flow path.

[0031] Figure 11It is a schematic diagram of a scroll flow path under axial observation of a centrifugal compressor according to an embodiment.

[0032] Figure 12 It is an explanatory diagram for explaining the shapes of the diffuser part and the scroll part at the angular positions θ1 and θ2 of the volute according to an embodiment.

[0033] Figure 13 It is an explanatory diagram for explaining the shapes of the diffuser part and the scroll part at the angular positions θ3 and θ4 of the volute according to an embodiment.

[0034] Figure 14 It is an explanatory diagram for explaining the shapes of the diffuser part and the scroll part of the volute of the comparative example.

[0035] Figure 15 It is an explanatory diagram for explaining the shapes of the diffuser part and the scroll part of the volute of the comparative example. Detailed Embodiments

[0036] Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the constituent parts described as embodiments or shown in the drawings are not intended to limit the scope of the present disclosure thereto, but are merely illustrative examples.

[0037] For example, expressions indicating relative or absolute arrangements such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric", or "coaxial" not only strictly represent such arrangements, but also represent a state of relative displacement in such a manner that there are tolerances or angles and distances that can achieve the same function.

[0038] For example, expressions indicating a state where things are equal such as "identical", "equal", and "homogeneous" not only strictly represent an equal state, but also represent a state where there are tolerances or differences to the extent that the same function can be achieved.

[0039] For example, expressions indicating shapes such as a quadrilateral shape and a cylindrical shape not only represent shapes such as a quadrilateral shape and a cylindrical shape in a strictly geometric sense, but also represent shapes including concavo-convex portions, chamfered portions, etc. within a range where the same effect can be obtained.

[0040] On the other hand, the expression of "comprising", "including", or "having" a constituent element is not an exclusive expression that excludes the existence of other constituent elements.

[0041] It should be noted that for the same structure, the same reference numerals may sometimes be used and the description may be omitted.

[0042] (Centrifugal Compressor, Turbocharger)

[0043] Figure 1This is an explanatory diagram showing the structure of a turbocharger with a centrifugal compressor according to an embodiment. Figure 2 This is a schematic cross-sectional view showing the compressor side of a turbocharger with a centrifugal compressor according to an embodiment, and is a schematic cross-sectional view including the axis of the centrifugal compressor.

[0044] As Figure 1 , 2 shown, the centrifugal compressor 1 of some embodiments of the present disclosure includes an impeller 2 and a volute 3 configured to rotatably house the impeller 2. As Figure 2 shown, the volute 3 at least includes a diffuser portion 4 forming a diffuser flow path 40 of the centrifugal compressor 1 and a scroll portion 5 forming a scroll flow path 50 of the centrifugal compressor 1. The diffuser flow path 40 is a flow path for guiding the fluid that has passed through the impeller 2 to the spiral scroll flow path 50 provided around the impeller 2.

[0045] The centrifugal compressor 1 can be applied to, for example, automotive, marine, or power generation turbochargers 10, other industrial centrifugal compressors, blowers, etc. In the illustrated embodiment, the centrifugal compressor 1 is mounted on the turbocharger 10. As Figure 1 shown, the turbocharger 10 includes a centrifugal compressor 1, a turbine 11, and a rotating shaft 12. The turbine 11 includes a turbine rotor 13 mechanically connected to the impeller 2 via the rotating shaft 12 and a turbine housing 14 that rotatably houses the turbine rotor 13.

[0046] In the illustrated embodiment, as Figure 1 shown, the turbocharger 10 further includes a bearing 15 that rotatably supports the rotating shaft 12 and a bearing housing 16 configured to house the bearing 15. The bearing housing 16 is disposed between the volute 3 and the turbine housing 14 and is mechanically connected to the volute 3 and the turbine housing 14 by fastening members such as fastening bolts.

[0047] Hereinafter, for example, as Figure 1 shown, the axis CA of the centrifugal compressor 1, that is, the direction in which the axis of the impeller 2 extends, is set as the axial direction X, and the direction orthogonal to the axis CA is set as the radial direction Y. The upstream side in the suction direction of the centrifugal compressor 1 in the axial direction X, that is, the side where the fluid inlet 31 is located relative to the impeller 2 (left side in the figure) is set as the front side XF. In addition, the downstream side in the suction direction of the centrifugal compressor 1 in the axial direction X, that is, the side where the impeller 2 is located relative to the fluid inlet 31 (right side in the figure) is set as the rear side XR.

[0048] In the illustrated embodiment, as Figure 1As shown, the volute 3 is formed with a fluid inlet 31 for introducing a fluid (e.g., air) from the outside of the volute 3 and a fluid outlet 32 ​​for discharging the fluid that has passed through the impeller 2 and the vortex flow path 50 to the outside of the volute 3. The turbine housing 14 is formed with an exhaust gas inlet 141 for introducing exhaust gas into the interior of the turbine housing 14 and an exhaust gas outlet 142 for discharging the exhaust gas that has passed through the turbine rotor 13 to the outside of the turbine housing 14.

[0049] like Figure 1 As shown, the rotating shaft 12 has a length direction along the axial direction X. The rotating shaft 12 is mechanically connected to the impeller 2 on one side (front side XF) in the length direction, and is mechanically connected to the turbine rotor 13 on the other side (rear side XR) in the length direction. It should be noted that "along a certain direction" in the present disclosure includes not only a certain direction, but also a direction inclined relative to a certain direction.

[0050] The turbocharger 10 rotates the turbine rotor 13 using exhaust gas introduced into the interior of the turbine housing 14 through the exhaust gas inlet 141 from an exhaust gas generating device (not shown) (for example, an internal combustion engine such as an engine). Since the impeller 2 is mechanically connected to the turbine rotor 13 via the rotating shaft 12, it rotates in conjunction with the rotation of the turbine rotor 13. The turbocharger 10 compresses the fluid introduced into the interior of the volute 3 through the fluid inlet 31 by rotating the impeller 2, and delivers the fluid to the fluid supply destination (for example, an internal combustion engine such as an engine) through the fluid discharge port 32.

[0051] (impeller)

[0052] like Figure 2 As shown, the impeller 2 includes a hub 21 and a plurality of impeller blades 23 provided on an outer surface 22 of the hub 21. Since the hub 21 is mechanically fixed to one side of the rotating shaft 12, the hub 21 and the plurality of impeller blades 23 are provided in a manner capable of rotating integrally with the rotating shaft 12 around the axis CA of the impeller 2. The impeller 2 is configured to guide the fluid introduced from the front side XF in the axial direction X to the outside in the radial direction Y. In the illustrated embodiment, the plurality of impeller blades 23 are respectively arranged with intervals between each other in the circumferential direction around the axis CA. A gap (interval) is formed between the top ends 24 of the plurality of impeller blades 23 and the shroud surface 61 curved into a convex shape in a manner opposite to the top ends 24.

[0053] (Snail Shell)

[0054] In the illustrated embodiment, Figure 2 As shown, the volute 3 has an intake air path portion 7 forming an intake air path 70 for guiding the fluid from the outside of the volute 3 to the impeller 2, a shroud portion 6 having a shroud surface 61, and a vortex portion 5 forming the above-mentioned vortex flow path 50 for guiding the fluid passing through the impeller 2 to the outside of the volute 3.

[0055] An intake air flow path 70, a diffuser flow path 40, and a scroll flow path 50 are respectively formed inside the volute 3. The scroll flow path 50 is located radially outside with respect to the impeller 2. The intake air flow path portion 7 has an inner wall surface 71 that forms the intake air flow path 70 and extends along the axial direction X. The above-mentioned fluid inlet 31 is formed at the front side XF end of the inner wall surface 71. The scroll portion 5 has an inner peripheral surface 51 that forms the scroll flow path 50.

[0056] The diffuser portion 4 has: a shroud side flow surface 41 that forms the front side XF portion of the diffuser flow path 40; a hub side flow surface 42 that is disposed opposite to the shroud side flow surface 41 at a position rearward XR from the shroud side flow surface 41 and forms the rear side XR portion of the diffuser flow path 40. As Figure 2 shown in the cross-section along the axis CA, the shroud side flow surface 41 and the hub side flow surface 42 respectively extend in a direction intersecting (orthogonal in the illustrated example) with the axis CA.

[0057] The above-mentioned diffuser portion 4 is provided between the shroud portion 6 and the scroll portion 5. In the illustrated embodiment, the volute 3 forms an impeller chamber 60 for housing the impeller 2 inside it. The shroud surface 61 forms the front side XF portion of the impeller chamber 60. The volute 3 has an impeller chamber forming surface 33 that is located rearward XR with respect to the shroud surface 61 and forms the rear side XR portion of the impeller chamber 60.

[0058] The inlet of the diffuser flow path 40 communicates with the impeller chamber 60, and the outlet of the diffuser flow path 40 communicates with the scroll flow path 50. In the illustrated embodiment, the upstream end of the shroud side flow surface 41 is smoothly connected to the downstream end of the shroud surface 61. The upstream end of the hub side flow surface 42 is connected to the outer peripheral end of the impeller chamber forming surface 33 via a stepped surface 34, and the downstream end of the hub side flow surface 42 is smoothly connected to one end of the inner peripheral surface 51 of the scroll portion 5.

[0059] The fluid introduced into the inside of the volute 3 from the fluid inlet 31 flows rearward XR in the intake air flow path 70 and is then guided to the impeller 2 (impeller chamber 60). The fluid that has passed through the impeller 2 flows successively in the diffuser flow path 40 and the scroll flow path 50 and is then discharged to the outside of the volute 3 from the fluid outlet 32.

[0060] (Distance ratio Tb / Ta)

[0061] Figures 3 to 6 are respectively explanatory diagrams for explaining the shapes of the diffuser portion and the scroll portion of the volute of an embodiment. In Figures 3 to 6 it schematically shows a cross-section along the axis CA of the centrifugal compressor 1.

[0062] As Figures 3 to 6As shown, the flow path width of the diffuser flow path 40 along the axial direction X of the centrifugal compressor 1 is defined as Ta, and the shortest distance from the start end position P1, which is the connection position of the inner peripheral surface 51 of the scroll portion 5 and the hub side flow path surface 42 of the diffuser flow path 40, to the imaginary circular arc VC that is tangent to the end position P2, which is the end position on the opposite side of the start end position P1 in the inner peripheral surface 51, is defined as Tb. It should be noted that for the shortest distance Tb, the direction from the start end position P1 to the front side XF is set as positive, and the direction from the start end position P1 to the rear side XR is set as negative.

[0063] The start end position P1 is the rear end on the axial direction X in the inner peripheral surface 51 and is the position where the radius of curvature changes from infinite (a straight line) to finite. In addition, the end position P2 is located on the UD side in one direction relative to the start end position P1. Here, the one direction UD is the counterclockwise direction in the cross-section along the axis CA of the centrifugal compressor 1, centered on the center SC of the scroll flow path 50 (the direction that goes from the rear side XR to the front side XF in the circumferential direction around the center SC on the outer side in the radial direction Y and goes from the front side XF to the rear side XR in the circumferential direction around the center SC on the inner side in the radial direction Y), and the UD side in one direction is its downstream side.

[0064] In Figures 3 to 6 the illustrated embodiment, in the cross-section along the axis CA of the centrifugal compressor 1, the inner peripheral surface 51 includes a first circular arc portion 52 extending from the start end position P1 to the UD side in one direction and a second circular arc portion 53 formed on the UD side in one direction relative to the first circular arc portion 52 and including at least the end position P2. In Figures 3 to 6 it, the first circular arc portion 52 is indicated by a single-dot dash line. The first circular arc portion 52 is formed such that its radius of curvature R1 is constant from the upstream end to the downstream end in the one direction UD. In addition, the second circular arc portion 53 is formed such that its radius of curvature R2 is constant from the upstream end to the downstream end in the one direction UD. The imaginary circular arc VC is connected to the second circular arc portion 53 including the end position P2, and its radius of curvature R0 is the same as the radius of curvature R2. The second circular arc portion 53 is formed such that its upstream end is smoothly connected to the downstream end of the first circular arc portion 52 at the connection position P3 with the downstream end of the first circular arc portion 52.

[0065] It should be noted that the shape of the inner peripheral surface 51 is not limited to the illustrated embodiment. For example, the inner peripheral surface 51 may also be formed such that its radius of curvature continuously decreases as it goes to the UD side in one direction.

[0066] As Figures 3 to 6As shown, a diffuser outlet flange portion 54 is formed in the volute 3. The diffuser outlet flange portion 54 includes a second arc portion 53 (inner peripheral surface 51) including a terminal position P2 and a shroud side flow path surface 41 of the diffuser flow path 40. In the illustrated embodiment, the diffuser outlet flange portion 54 further includes an inner wall surface 55 having a length T along the axial direction X. One end of the inner wall surface 55 is connected to the downstream end of the second arc portion 53 at the terminal position P2, and the other end of the inner wall surface 55 is connected to the downstream end 43 of the shroud side flow path surface 41. It should be noted that in the illustrated embodiment, the inner wall surface 55 extends linearly along the axial direction in a cross section along the axis CA of the centrifugal compressor 1, but the inner wall surface 55 is not limited to this shape. The inner wall surface 55 may be curved convexly toward the radially outer side, for example. In addition, when the flow path width of the diffuser flow path 40 is not constant, as the flow path width Ta of the diffuser flow path 40, the flow path width at the outlet (communication port with the scroll flow path 50) 44 of the diffuser flow path 40 including the downstream end 43 of the shroud side flow path surface 41 may also be adopted.

[0067] As Figures 3 to 6 shown, the fluid flowing into the scroll flow path 50 from the outlet of the diffuser flow path 40 has a swirling velocity component, and thus a rotating flow SF flowing along the inner peripheral surface 51 toward one direction UD side is formed. Such a rotating flow SF flows along the first arc portion 52 and the second arc portion 53, and then, on the downstream side of the diffuser outlet flange portion 54, converges with the outlet flow DF of the diffuser flow path 40 flowing into the scroll flow path 50 from the outlet of the diffuser flow path 40.

[0068] The rotating flow SF flows along a virtual arc VC on the downstream side of the diffuser outlet flange portion 54. Figure 3 The cross-sectional shape of the volute 3 shown satisfies the condition of Tb / Ta = 1.0. Figure 4 The cross-sectional shape of the volute 3 shown satisfies the condition of Tb / Ta = 1.5. As Figure 3 、 Figure 4 shown, when Tb / Ta ≥ 1.0, the rotating flow SF on the downstream side of the diffuser outlet flange portion 54 can make the inclination angle with respect to the outlet flow DF gentle, and thus the interference between the rotating flow SF and the outlet flow DF at the converging portion can be effectively suppressed. It should be noted that as the value of Tb / Ta becomes larger than 1.0, the thickness T of the diffuser outlet flange portion becomes larger, and thus the possibility of generating a low flow velocity region WA called wake increases at the position immediately downstream of the diffuser outlet flange portion 54 in the scroll flow path 50. If the wake is large, the wake loss of the rotating flow SF increases, and thus the efficiency of the centrifugal compressor 1 may decrease. Therefore, in order to suppress the wake loss of the rotating flow SF, it is preferable that the value of Tb / Ta does not become too large compared to 1.0. The volute 3 preferably satisfies the relationship of Tb / Ta ≤ 1.75, and more preferably satisfies the relationship of Tb / Ta ≤ 1.60.

[0069] Figure 5 The cross-sectional shape of the volute 3 shown satisfies the condition of Tb / Ta = 0.5. Figure 6 The cross-sectional shape of the volute 3 shown satisfies the condition of Tb / Ta < 0. As Figure 5 and Figure 6 shown, as the value of Tb / Ta becomes smaller than 1.0, the degree of interference between the rotational flow SF on the downstream side of the diffuser outlet flange portion 54 and the outlet flow DF of the diffuser flow path 40 flowing into the vortex flow path 50 increases, and the degree of blockage of the outlet flow DF of the diffuser flow path 40 increases. In Figure 5 , the shroud side (front side XF) of the outlet flow DF is blocked by the rotational flow SF on the downstream side of the diffuser outlet flange portion 54, while in Figure 6 , the outlet flow DF is blocked from the shroud side to the hub side (rear side XR) by the rotational flow SF on the downstream side of the diffuser outlet flange portion 54. If at least the shroud side of the outlet flow DF is blocked, the resistance of the fluid flowing through the diffuser flow path 40 increases, and diffuser stall may be induced. If diffuser stall is induced, the efficiency of the centrifugal compressor 1 drops extremely, and surges caused by the diffuser stall are induced, and the operating range of the centrifugal compressor 1 may be reduced. In addition, as the value of Tb / Ta becomes smaller, the thickness T of the diffuser outlet flange portion 54 becomes smaller, but if the thickness T becomes too small, a deficiency of the diffuser outlet flange portion 54 may occur, which is not preferable. It should be noted that the adverse effect of the wake loss of the rotational flow SF on the efficiency of the centrifugal compressor 1 is smaller than the adverse effect of the blockage of the outlet flow DF on the efficiency of the centrifugal compressor 1. Therefore, regarding the value of Tb / Ta, it is preferably set to be larger than 1.0 rather than smaller than 1.0.

[0070] Figure 7 is a schematic view of a vortex flow path in an axial view of a centrifugal compressor according to an embodiment. As Figure 7 shown, regarding the angular position θ around the vortex center O in the above-mentioned vortex flow path 50, the angular position θ is defined such that the convergence position P of the start 501 and the end 502 of the winding of the vortex flow path 50 is 60 degrees and the angle gradually increases toward the downstream side of the vortex flow path 50 (the clockwise direction around the vortex center O in the figure). In addition, the range of the angular position θ from 60 degrees to 180 degrees is set as the upstream side range RU, and the range of the angular position θ from 180 degrees to 360 degrees is defined as the downstream side range RD. In addition, as Figure 7As shown, with respect to a cross-section in the case where the scroll flow path 50 is cut by a plane including the axis CA of the centrifugal compressor 1 at a circumferential position where the angular position is θ, the cross-sectional area of the scroll flow path 50 is set as A, and the distance from the scroll center O to the center SC in the cross-section of the scroll flow path 50 is set as R. The scroll flow path 50 is formed such that A / R increases as the angular position θ increases. In a certain embodiment, the scroll flow path 50 is formed such that the value of A / R increases at a constant slope in at least one of the upstream range RU and the downstream range RD.

[0071] Figure 8 It is an explanatory diagram of a volute for explaining an embodiment, and is an explanatory diagram showing the relationship between the angular position and the distance ratio Tb / Ta in the scroll flow path. In Figure 8 it, the above-mentioned angular position θ is set as the horizontal axis, and the above-mentioned distance ratio Tb / Ta is set as the vertical axis. It should be noted that, in Figure 8 the embodiment shown, as the angular position θ of the volute 3 increases, A / R increases, and correspondingly, Tb / Ta increases.

[0072] As Figure 8 shown, the volute 3 of some embodiments satisfies the relationship of Tb / Ta≥1.0 in the range where the above-mentioned angular position θ is from 180 degrees to 360 degrees, that is, the downstream range RD.

[0073] In the case of assuming that the value of Tb / Ta is too small (the case where the relationship of Tb / Ta<1.0 is satisfied), the outlet flow DF of the diffuser flow path 40 and the rotational flow SF in the scroll flow path 50 interfere with each other. As a result, the resistance of the fluid passing through the diffuser flow path 40 increases, and diffuser stall may be induced. If diffuser stall is induced, the efficiency of the centrifugal compressor 1 drops extremely, and surges caused by diffuser stall are induced, and the operating range of the centrifugal compressor 1 may be reduced. To avoid this situation, it is preferable to satisfy the relationship of Tb / Ta≥1.0. According to the above structure, the volute 3 satisfies the relationship of Tb / Ta≥1.0 in the range where the angular position θ is from 180 degrees to 360 degrees (downstream range RD), so in the above-mentioned downstream range RD, the interference between the outlet flow DF of the diffuser flow path 40 and the rotational flow SF in the scroll flow path 50 can be suppressed. Thereby, the blockage of the diffuser flow path 40 can be suppressed, and thus the efficiency drop and the reduction of the operating range of the centrifugal compressor 1 can be suppressed.

[0074] In some embodiments, as Figure 8 shown, the above-mentioned volute 3 satisfies the relationship of Tb / Ta≥0.5 in the range where the above-mentioned angular position θ is from 60 degrees to 180 degrees, that is, the upstream range RU.

[0075] In order to suppress the interference between the outlet flow DF of the diffusion flow path 40 and the rotating flow SF in the vortex flow path 50, it is preferable that Tb / Ta≥1.0 also in the range of the angular position θ of the volute 3 from 60 degrees to 180 degrees (upstream side range RU). However, the closer to the winding start 501 side of the vortex flow path 50, the smaller the cross-sectional area A of the vortex flow path 50. Therefore, in the upstream side range RU, it may be difficult to satisfy the relationship of Tb / Ta≥1.0. According to the above structure, in the range of the angular position θ from 60 degrees to 180 degrees (upstream side range RU), the relationship of Tb / Ta≥0.5 is satisfied. In this case, in the upstream side range RU, the interference between the outlet flow DF of the diffusion flow path 40 and the rotating flow SF in the vortex flow path 50 can be suppressed. Thereby, the blockage of the diffusion flow path 40 can be suppressed, and thus the efficiency reduction and the narrowing of the operating range of the centrifugal compressor 1 can be suppressed. It should be noted that in some embodiments, the above volute 3 may also be formed in such a way that the relationship of Tb / Ta≥1.0 is satisfied in the upstream side range RU and the downstream side range RD. In this case, the interference between the outlet flow DF and the rotating flow SF can be effectively suppressed.

[0076] In some embodiments, as Figure 8 shown, the above volute 3 satisfies the relationship of Tb / Ta≤1.75 in the range of the above angular position θ from 180 degrees to 360 degrees, that is, the downstream side range RD.

[0077] In the case where the value of Tb / Ta is assumed to be too large (the case where the relationship of Tb / Ta>1.75 is satisfied), along with the increase in the thickness T of the diffusion outlet flange portion 54, the above region WA expands and the wake loss increases. Therefore, the efficiency reduction of the centrifugal compressor 1 may be caused. According to the above structure, in the range of the angular position θ from 180 degrees to 360 degrees (downstream side range RD), the relationship of Tb / Ta≤1.75 is satisfied. In this case, in the downstream side range RD, the efficiency reduction of the centrifugal compressor 1 caused by the wake loss can be suppressed. It should be noted that in some embodiments, the above volute 3 satisfies the relationship of Tb / Ta≤1.75 in the upstream side range RU and the downstream side range RD. In this case, in the upstream side range RU and the downstream side range RD, the efficiency reduction of the centrifugal compressor 1 caused by the wake loss can be suppressed.

[0078] (Crossing angle α)

[0079] Figure 9 is an explanatory diagram for explaining the shapes of the diffusion portion and the vortex portion of the volute of an embodiment. As Figure 9As shown, the intersection angle between the imaginary tangent line VT that is tangent to the terminal position P2 on the inner peripheral surface 51 of the scroll portion 5 and the radial direction Y of the centrifugal compressor 1 is defined as α. It should be noted that two intersection angles are formed by the imaginary tangent line VT and the radial direction Y, and the smaller of the two intersection angles is set as the intersection angle α.

[0080] In some of the above embodiments, the distance ratio Tb / Ta is set as a parameter value related to the shape of the volute 3. However, in other embodiments, the intersection angle α can also be set as the above parameter value. If the intersection angle α increases, the inclination angle of the rotational flow SF on the downstream side of the diffuser outlet flange portion 54 with respect to the outlet flow DF increases correspondingly with the intersection angle α. If the above inclination angle increases, the degree of interference between the rotational flow SF and the outlet flow DF of the diffuser passage 40 increases, and the degree of blockage of the outlet flow DF of the diffuser passage 40 increases. Therefore, in order to suppress the blockage of the outlet flow DF, it is preferable to make the intersection angle α small. The volute 3 preferably satisfies the relationship of α ≤ 70°, and more preferably satisfies the relationship of α ≤ 50°.

[0081] Figure 10 It is an explanatory diagram of the volute for explaining an embodiment, and is an explanatory diagram showing the relationship between the angular position in the scroll passage and the intersection angle α. In Figure 10 it, the above angular position θ is set as the horizontal axis, and the above intersection angle α is set as the vertical axis. It should be noted that in the Figure 10 shown embodiment, the intersection angle α of the volute 3 decreases as the angular position θ increases.

[0082] As Figure 10 shown, the volute 3 of some embodiments satisfies the relationship of α ≤ 50° in the range of the above angular position θ from 180 degrees to 360 degrees, that is, the downstream range RD.

[0083] In the case where it is assumed that the intersection angle α is too large, the outlet flow DF of the diffuser passage 40 and the rotational flow SF in the scroll passage 50 interfere with each other. As a result, the resistance of the fluid passing through the diffuser passage 40 increases, and diffuser stall may be induced. If diffuser stall is induced, the efficiency of the centrifugal compressor 1 drops extremely, and surges caused by diffuser stall are induced, and the operating range of the centrifugal compressor 1 may be reduced. To avoid this situation, it is preferable to satisfy the relationship of α ≤ 50°. According to the above structure, the volute 3 satisfies the relationship of α ≤ 50° in the range of the angular position θ from 180 degrees to 360 degrees (downstream range RD). Therefore, in the downstream range RD, the interference between the outlet flow DF of the diffuser passage 40 and the rotational flow SF in the scroll passage 40 can be suppressed. As a result, the blockage of the diffuser passage 40 can be suppressed, and thus the efficiency drop and the reduction of the operating range of the centrifugal compressor 1 can be suppressed. It should be noted that this embodiment can be implemented independently.

[0084] In some embodiments, such as Figure 10 shown, in the upstream range RU where the angular position θ of the above-mentioned volute 3 ranges from 60 degrees to 180 degrees, the relationship of α ≤ 70° is satisfied.

[0085] In order to suppress the interference between the outlet flow DF of the diffuser passage 40 and the rotating flow SF in the scroll passage 50, it is preferable that in the range where the angular position θ of the volute 3 ranges from 60 degrees to 180 degrees (upstream range RU), the relationship of α ≤ 50° is also satisfied. However, the closer to the winding start 501 side of the scroll passage 50, the smaller the cross-sectional area A of the scroll passage 50. Therefore, in the upstream range RU, it is sometimes difficult to satisfy the relationship of α ≤ 50°. According to the above structure, in the range where the angular position θ ranges from 60 degrees to 180 degrees (upstream range RU), the relationship of α ≤ 70° is satisfied. In this case, in the upstream range RU, the interference between the outlet flow DF of the diffuser passage 40 and the rotating flow SF in the scroll passage 50 can be suppressed. Thus, the blockage of the diffuser passage 40 can be suppressed, and therefore the efficiency reduction and the narrowing of the operating range of the centrifugal compressor 1 can be suppressed. It should be noted that in some embodiments, the above-mentioned volute 3 may also be formed in such a way that the relationship of α ≤ 50° is satisfied in the upstream range RU and the downstream range RD. In this case, the interference between the outlet flow DF and the rotating flow SF can be effectively suppressed.

[0086] In some of the above embodiments, either the distance ratio Tb / Ta or the crossing angle α is set as a parameter value related to the shape of the volute 3, but in other embodiments, both the distance ratio Tb / Ta and the crossing angle α may be set as the above parameter values.

[0087] In some embodiments, in the downstream range RD where the angular position θ of the above-mentioned volute 3 ranges from 180 degrees to 360 degrees, the relationships of Tb / Ta ≥ 1.0 and α ≤ 50° are satisfied.

[0088] According to the above structure, in the range where the angular position θ of the volute 3 ranges from 180 degrees to 360 degrees (downstream range RD), not only the relationship of Tb / Ta ≥ 1.0 is satisfied but also the relationship of α ≤ 50° is satisfied. Therefore, compared with the case where only the relationship of Tb / Ta ≥ 1.0 is satisfied, in the downstream range RD, the interference between the outlet flow DF of the diffuser passage 40 and the rotating flow SF in the scroll passage 50 can be more effectively suppressed. Thus, the blockage of the diffuser passage 40 can be effectively suppressed, and therefore the efficiency reduction and the narrowing of the operating range of the centrifugal compressor 1 can be effectively suppressed.

[0089] In some embodiments, in the upstream range RU where the angular position θ of the above-mentioned volute 3 ranges from 60 degrees to 180 degrees, the relationships of Tb / Ta ≥ 0.5 and α ≤ 70° are satisfied.

[0090] According to the above structure, in the range where the angular position θ of the volute 3 is from 60 degrees to 180 degrees (the upstream side range RU), not only does it satisfy the relationship of Tb / Ta≥0.5, but also satisfies the relationship of α≤70°. Therefore, compared with the case where only the relationship of Tb / Ta≥0.5 is satisfied, in the upstream side range RU, the interference between the outlet flow DF of the diffuser passage 40 and the rotational flow SF in the scroll passage 50 can be more effectively suppressed. Thus, the blockage of the diffuser passage 40 can be effectively suppressed, and accordingly, the efficiency decline and the reduction of the operating range of the centrifugal compressor 1 can be effectively suppressed.

[0091] (Shape change in the circumferential direction of the scroll passage)

[0092] Figure 11 is a schematic diagram of the scroll passage of a centrifugal compressor in an axial view of an embodiment. As Figure 11 shown, the above-mentioned angular position θ includes the angular position θ1 and the angular position θ2 that is larger than the angular position θ1. Figure 12 is an explanatory diagram for explaining the shapes of the diffuser part and the scroll part at the angular positions θ1 and θ2 of the volute of an embodiment. In Figure 12 it schematically shows the volute 3 at the angular positions θ1 and θ2. In Figure 12 the inner peripheral surface 51 and the inner wall surface 55 of the scroll part 5 at the angular position θ1 are shown by solid lines, and the inner peripheral surface 51 and the inner wall surface 55 of the scroll part 5 at the angular position θ2 are shown by double-dot dash lines.

[0093] In some embodiments, as Figure 12 shown, when the length along the axial direction of the centrifugal compressor between the terminal position P2 and the downstream end 43 of the shroud side flow surface 41 of the diffuser passage 40 at the position where the angular position is θ1 is defined as T1, and the length along the axial direction between the terminal position P2 and the downstream end 43 of the shroud side flow surface 41 at the position where the angular position θ is θ2 which is larger than θ1 is defined as T2, the above-mentioned volute 3 satisfies the relationship of T1<T2. In the illustrated embodiment, the scroll passage 50 is formed such that the above-mentioned length T continuously or stepwise increases as it goes from the winding start 501 side to the winding end 502 side.

[0094] Generally, the length T along the axial direction of the centrifugal compressor 1 of the terminal position P2 and the downstream end 43 of the shroud side flow path surface 41 of the diffusion flow path 40 is set to be the same in the circumferential direction of the centrifugal compressor 1. However, in this case, if the shape is such that Tb / Ta and the crossing angle α satisfy the above relationships for each angular position θ, the shape on the winding end 502 side of the vortex flow path 50 becomes an inappropriate shape, which may lead to a decrease in the efficiency of the centrifugal compressor 1. According to the above structure, since the length T2 at the angular position θ2 is larger than the length T1 at the angular position θ1 for the volute 3, the vortex flow path 50 can be made into an appropriate shape for each angular position θ while maintaining the above relationships for Tb / Ta and the crossing angle α for each angular position θ. Thereby, a decrease in the efficiency of the centrifugal compressor 1 can be suppressed.

[0095] As Figure 11 shown, the above angular position θ includes the angular position θ3 and the angular position θ4 larger than the angular position θ3. Figure 13 is an explanatory diagram for explaining the shapes of the diffusion part and the vortex part at the angular positions θ3 and θ4 of the volute according to an embodiment. In Figure 13 , the volute 3 at the angular positions θ3 and θ4 is schematically shown. In Figure 13 , the inner circumferential surface 51, the inner wall surface 55, and the shroud side flow path surface 41 of the vortex part 5 at the angular position θ3 are represented by a one-dot chain line, and the inner circumferential surface 51, the inner wall surface 55, and the shroud side flow path surface 41 of the vortex part 5 at the angular position θ4 are represented by a solid line.

[0096] In some embodiments, as Figure 13 shown, when the length along the radial direction of the centrifugal compressor 1 from the axis CA of the centrifugal compressor 1 to the downstream end 43 of the shroud side flow path surface 41 of the diffusion flow path 40 at the position where the angular position θ is θ3 is defined as d1, and the length along the radial direction from the axis CA to the downstream end 43 of the shroud side flow path surface 41 at the position where the angular position θ is θ4 larger than θ3 is defined as d2, the above volute 3 satisfies the relationship of d1 > d2. In the illustrated embodiment, the diffusion flow path 40 is formed such that the length d along the radial direction of the centrifugal compressor 1 from the axis CA of the centrifugal compressor 1 to the downstream end 43 of the shroud side flow path surface 41 continuously or stepwise increases as going from the winding start 501 side to the winding end 502 side.

[0097] Generally, the length d along the radial direction of the centrifugal compressor 1 from the axis CA of the centrifugal compressor 1 to the downstream end 43 of the shroud-side flow surface 41 of the diffuser flow path 40 is set to be the same in the circumferential direction of the centrifugal compressor 1. However, in this case, if the shape is such that Tb / Ta and the crossing angle α satisfy the above relationships for each angular position θ, the shape of the winding end side of the scroll flow path 50 becomes an inappropriate shape, which may cause a decrease in the efficiency of the centrifugal compressor 1. According to the above structure, since the length d2 at the angular position θ4 is larger than the length d1 at the angular position θ3 in the volute 3, it is possible to maintain the above relationships of Tb / Ta and the crossing angle α for each angular position θ while making the scroll flow path 50 have an appropriate shape for each angular position θ. Thereby, a decrease in the efficiency of the centrifugal compressor 1 can be suppressed.

[0098] It should be noted that, in Figure 13 the embodiment shown, the above length T is the same at the angular positions θ3 and θ4, but the length T at the angular position θ4 may also be made larger than the length T at the angular position θ3 in the same manner as in some of the above embodiments.

[0099] The centrifugal compressor 1 of some embodiments includes the above volute 3. In this case, through the volute 3, interference between the outlet flow DF of the diffuser flow path 40 and the rotating flow SF in the scroll flow path 50 can be suppressed. Thereby, blockage of the diffuser flow path 40 can be suppressed, and thus a decrease in the efficiency of the centrifugal compressor 1 and a reduction in the operating range can be suppressed.

[0100] The present disclosure is not limited to the above embodiments, and also includes embodiments obtained by modifying the above embodiments and embodiments obtained by appropriately combining these embodiments.

[0101] The content described in some of the above embodiments can be understood as follows, for example.

[0102] 1) The volute (3) of at least one embodiment of the present disclosure is the volute (3) of the centrifugal compressor (1), and includes:

[0103] a diffuser portion (4) that forms the diffuser flow path (40) of the centrifugal compressor (1);

[0104] a scroll portion (5) that forms the scroll flow path (50) of the centrifugal compressor (1);

[0105] When the flow path width of the diffusion flow path (40) along the axis of the centrifugal compressor (1) is defined as Ta, and the shortest distance from the connection position (starting end position P1) of the inner peripheral surface (51) of the scroll part (5) to the hub side flow path surface (42) of the diffusion flow path (40) to the imaginary circular arc (VC) tangent to the end position (terminal position P2) on the side opposite to the starting end position (P1) in the inner peripheral surface (51) is defined as Tb, with respect to the angular position (θ) around the scroll center (O) in the scroll flow path (50), taking the confluence position (P) of the start of winding (501) and the end of winding (502) of the scroll flow path (50) as 60 degrees and defining the angular position (θ) in such a way that the angle gradually increases toward the downstream side of the scroll flow path (50),

[0106] (501) and the end of winding (502) is set to 60 degrees and the angular position (θ) is defined in such a way that the angle gradually increases toward the downstream side of the scroll flow path (50),

[0107] In the range (downstream side range RD) where the angular position (θ) is from 180 degrees to 360 degrees, the relationship Tb / Ta≥1.0 is satisfied.

[0108] In the case where it is assumed that the value of Tb / Ta is too small (the case where the relationship Tb / Ta<1.0 is satisfied), the outlet flow (DF) of the diffusion flow path and the rotational flow (SF) in the scroll flow path interfere. As a result, the resistance of the fluid in the diffusion flow path (40) increases, and diffusion stall may be induced. If diffusion stall is induced, the efficiency of the centrifugal compressor (1) drops extremely, and surges caused by the diffusion stall are induced, and the operating range of the centrifugal compressor (1) may be narrowed. To avoid this situation, it is preferable to satisfy the relationship Tb / Ta≥1.0. According to the structure of 1) above, the volute (3) satisfies the relationship Tb / Ta≥1.0 in the range (downstream side range RD) where the angular position (θ) is from 180 degrees to 360 degrees. Therefore, in the above downstream side range, the interference between the outlet flow (DF) of the diffusion flow path and the rotational flow (SF) in the scroll flow path can be suppressed. As a result, the blockage of the diffusion flow path (40) can be suppressed, and thus the decrease in the efficiency of the centrifugal compressor (1) and the narrowing of the operating range can be suppressed.

[0109] 2) In some embodiments, according to the volute (3) described in 1) above,

[0110] In the range (upstream side range RU) where the angular position (θ) is from 60 degrees to 180 degrees, the relationship Tb / Ta≥0.5 is satisfied.

[0111] According to the structure in 2) above, in the range of the angular position (θ) from 60 degrees to 180 degrees (the upstream range RU), the relationship of Tb / Ta ≥ 0.5 is satisfied. In this case, in the upstream range (RU), the interference between the outlet flow (DF) of the diffusion flow path and the rotational flow (SF) in the vortex flow path can be suppressed. Thereby, the blockage of the diffusion flow path (40) can be suppressed, and thus the efficiency decrease and the reduction of the operating range of the centrifugal compressor (1) can be suppressed.

[0112] 3) In some embodiments, according to the volute (3) described in 1) or 2) above,

[0113] In the range of the angular position (θ) from 180 degrees to 360 degrees (the downstream range RD), the relationship of Tb / Ta ≤ 1.75 is satisfied.

[0114] In the case where the value of Tb / Ta is assumed to be too large (the case where the relationship of Tb / Ta > 1.75 is satisfied), along with the increase in the thickness (T) of the diffusion outlet flange portion (54), the wake loss increases, and thus the efficiency decrease of the centrifugal compressor (1) may be caused. According to the structure in 3) above, in the range of the angular position (θ) from 180 degrees to 360 degrees (the downstream range RD), the relationship of Tb / Ta ≤ 1.75 is satisfied. In this case, in the downstream range (RD), the efficiency decrease of the centrifugal compressor (1) caused by the wake loss can be suppressed.

[0115] 4) In some embodiments, according to the volute (3) described in any one of 1) to 3) above,

[0116] In the case where the intersection angle of the imaginary tangent line (VT) tangent to the terminal position (P2) in the inner peripheral surface (51) of the vortex portion (5) and the radial direction (Y) of the centrifugal compressor (1) is defined as α,

[0117] In the range of the angular position (θ) from 180 degrees to 360 degrees (the downstream range RD), the relationship of α ≤ 50° is satisfied.

[0118] According to the structure in 4) above, the volute (3) in the range of the angular position (θ) from 180 degrees to 360 degrees (the downstream range RD) satisfies not only the relationship of Tb / Ta ≥ 1.0 but also the relationship of α ≤ 50°. Therefore, compared with the case where only the relationship of Tb / Ta ≥ 1.0 is satisfied, in the downstream range (RD), the interference between the outlet flow (DF) of the diffusion flow path and the rotational flow (SF) in the vortex flow path can be more effectively suppressed. Thereby, the blockage of the diffusion flow path (40) can be effectively suppressed, and thus the efficiency decrease and the reduction of the operating range of the centrifugal compressor (1) can be effectively suppressed.

[0119] 5) In some embodiments, for the volute (3) described in 4) above,

[0120] in the range (upstream side range RU) where the angular position (θ) is from 60 degrees to 180 degrees, the relationship α ≤ 70° is satisfied.

[0121] According to the structure of 5) above, in the range (upstream side range RU) where the angular position (θ) is from 60 degrees to 180 degrees, the relationship α ≤ 70° is satisfied. In this case, in the upstream side range (RU), interference between the outlet flow (DF) of the diffuser flow path and the rotational flow (SF) in the volute flow path can be suppressed. Thereby, blockage of the diffuser flow path (40) can be suppressed, and thus a decrease in the efficiency of the centrifugal compressor (1) and a reduction in the operating range can be suppressed.

[0122] 6) The volute (3) of at least one embodiment of the present disclosure is the volute (3) of a centrifugal compressor (1), and includes:

[0123] a diffuser portion (4) that forms the diffuser flow path (40) of the centrifugal compressor (1);

[0124] a volute portion (5) that forms the volute flow path (50) of the centrifugal compressor (1);

[0125] When the crossing angle of the imaginary tangent line (VT) tangent to the end position (P2), which is the opposite side of the starting end position (P1) of the connection position between the inner peripheral surface (51) of the volute portion (5) and the hub side flow path surface (42) of the diffuser flow path (40), with the radial direction (Y) of the centrifugal compressor (1) is defined as α, and for the angular position (θ) around the volute center (O) in the volute flow path (50), when the angular position (θ) is defined in such a way that the confluence position (P) of the start of winding (501) and the end of winding (502) of the volute flow path (50) is 60 degrees and the angle gradually increases toward the downstream side of the volute flow path (50),

[0126] in the range (downstream side range RD) where the angular position (θ) is from 180 degrees to 360 degrees, the relationship α ≤ 50° is satisfied.

[0127] In the case where the assumed crossing angle α is too large, the outlet flow (DF) of the diffuser flow path and the rotating flow (SF) in the scroll flow path interfere with each other. As a result, the resistance of the fluid in the diffuser flow path (40) increases, which may induce diffuser stall. If diffuser stall is induced, the efficiency of the centrifugal compressor (1) drops extremely, and surges caused by diffuser stall are induced, and the operating range of the centrifugal compressor (1) may be narrowed. According to the structure of the above 6), the volute (3) satisfies the relationship of α ≤ 50° in the range of the angular position (θ) from 180 degrees to 360 degrees (downstream range RD). Therefore, in the downstream range (RD), the interference between the outlet flow (DF) of the diffuser flow path and the rotating flow (SF) in the scroll flow path can be suppressed. Thereby, blockage of the diffuser flow path (40) can be suppressed, and thus a decrease in the efficiency of the centrifugal compressor (1) and a narrowing of the operating range can be suppressed.

[0128] 7) In some embodiments, for the volute (3) described in the above 6),

[0129] in the range of the angular position (θ) from 60 degrees to 180 degrees (upstream range RU), the relationship of α ≤ 70° is satisfied.

[0130] According to the structure of the above 7), in the range of the angular position (θ) from 60 degrees to 180 degrees (upstream range RU), the relationship of α ≤ 70° is satisfied. In this case, in the upstream range (RU), the interference between the outlet flow (DF) of the diffuser flow path and the rotating flow (SF) in the scroll flow path can be suppressed. Thereby, blockage of the diffuser flow path (40) can be suppressed, and thus a decrease in the efficiency of the centrifugal compressor (1) and a narrowing of the operating range can be suppressed.

[0131] 8) In some embodiments, for the volute (3) described in any one of the above 1) to 7),

[0132] when the length along the axial direction of the centrifugal compressor (1) between the terminal position (P2) at the position where the angular position (θ) is θ1 and the downstream end (43) of the shroud side flow surface (41) of the diffuser flow path (40) is defined as T1, and the length along the axial direction between the terminal position (P2) at the position where the angular position (θ) is θ2 which is larger than θ1 and the downstream end (43) of the shroud side flow surface (41) is defined as T2,

[0133] the relationship of T1 < T2 is satisfied.

[0134] Generally, the length (T) along the axial direction of the centrifugal compressor (1) from the terminal position (P2) to the downstream end (43) of the shroud-side flow surface (41) of the diffuser flow path (40) is set to be the same in the circumferential direction of the centrifugal compressor (1). However, in this case, if the shape is such that Tb / Ta and the crossing angle α satisfy the above relationship for each angular position (θ), the shape on the winding end (502) side of the scroll flow path (50) becomes an inappropriate shape, which may lead to a decrease in the efficiency of the centrifugal compressor (1). According to the structure of the above 8), the above length T2 at the angular position θ2 of the volute (3) is larger than the above length T1 at the angular position θ1. Therefore, while maintaining the above relationship between Tb / Ta and the crossing angle α for each angular position (θ), the scroll flow path (50) can be made into an appropriate shape for each angular position (θ). Thereby, a decrease in the efficiency of the centrifugal compressor (1) can be suppressed.

[0135] 9) In some embodiments, according to the volute (3) described in any one of the above 1) to 8),

[0136] When the length along the radial direction (Y) of the centrifugal compressor (1) from the axis (CA) of the centrifugal compressor (1) to the downstream end (43) of the shroud-side flow surface (41) of the diffuser flow path (40) at the position where the angular position (θ) is θ3 is defined as d1, and the length along the radial direction (Y) from the axis (CA) to the downstream end (43) of the shroud-side flow surface (41) at the position where the angular position (θ) is θ4 which is larger than θ3 is defined as d2,

[0137] the relationship d1 > d2 is satisfied.

[0138] Generally, the length (d) along the radial direction (Y) of the centrifugal compressor (1) from the axis (CA) of the centrifugal compressor (1) to the downstream end (43) of the shroud-side flow surface (41) of the diffuser flow path (40) is set to be the same in the circumferential direction of the centrifugal compressor (1). However, in this case, if the shape is such that Tb / Ta and the crossing angle α satisfy the above relationship for each angular position (θ), the shape on the winding end (502) side of the scroll flow path (50) becomes an inappropriate shape, which may lead to a decrease in the efficiency of the centrifugal compressor (1). According to the structure of the above 9), the above length d2 at the angular position θ4 of the volute (3) is larger than the above length d1 at the angular position θ3. Therefore, while maintaining the above relationship between Tb / Ta and the crossing angle α for each angular position (θ), the scroll flow path (50) can be made into an appropriate shape for each angular position (θ). Thereby, a decrease in the efficiency of the centrifugal compressor (1) can be suppressed.

[0139] 10) The centrifugal compressor (1) according to at least one embodiment of the present disclosure includes the volute (3) described in any one of 1) to 9) above.

[0140] According to the structure of the above 10), through the volute (3), it is possible to suppress the interference between the outlet flow (DF) of the diffuser flow path and the rotational flow (SF) in the scroll flow path. Thus, it is possible to suppress the blockage of the diffuser flow path (40), and therefore it is possible to suppress the efficiency reduction and the narrowing of the operating range of the centrifugal compressor (1).

[0141] Explanation of Reference Numerals

[0142] 1 Centrifugal compressor;

[0143] 2 Impeller;

[0144] 21 Hub;

[0145] 22 Outer surface;

[0146] 23 Impeller blade;

[0147] 24 Tip;

[0148] 3, 03 Volute;

[0149] 31 Fluid inlet;

[0150] 32 Fluid outlet;

[0151] 33 Impeller chamber forming surface;

[0152] 34 Step surface;

[0153] 4, 04 Diffusion part;

[0154] 40, 040 Diffusion flow path;

[0155] 41, 041 Shroud side flow path surface;

[0156] 42, 042 Hub side flow path surface;

[0157] 43, 043 Downstream end;

[0158] 5, 05 Scroll part;

[0159] 50, 050 Scroll flow path;

[0160] 51, 051 Inner peripheral surface;

[0161] 52 First arc part;

[0162] 53 Second arc part;

[0163] 54, 054 Diffusion outlet flange part;

[0164] 55 Inner wall surface;

[0165] 6 Shroud part;

[0166] 60 Impeller chamber;

[0167] 61 Shroud surface;

[0168] 7 Inlet air flow path part;

[0169] 70 Inlet air flow path;

[0170] 71 Inner wall surface;

[0171] 10 Turbocharger;

[0172] 11 Turbine;

[0173] 12 Rotating shaft;

[0174] 13 Turbine rotor;

[0175] 14 Turbine housing;

[0176] 141 Exhaust gas inlet;

[0177] 142 Exhaust gas outlet;

[0178] 15 Bearing;

[0179] 16 Bearing housing;

[0180] A Cross-sectional area;

[0181] CA Axis;

[0182] DF Outlet flow;

[0183] O Vortex center;

[0184] P Confluence position;

[0185] P1, P01 Starting position;

[0186] P2, P02 Terminal position;

[0187] P3 Connection position;

[0188] R0, R1, R2 Radius of curvature;

[0189] RD Downstream side range;

[0190] RU Upstream side range;

[0191] SF Rotating flow;

[0192] Ta Flow path width of diffusion flow path;

[0193] Tb Shortest distance;

[0194] UD One direction;

[0195] VC Imaginary circular arc;

[0196] VT Imaginary tangent;

[0197] WA Area;

[0198] X Axial direction;

[0199] XF Front side;

[0200] XR Rear side;

[0201] Y Radial direction.

Claims

1. A volute, which is the volute of a centrifugal compressor, is characterized in that, Comprising: A diffuser section that forms a diffuser flow path of the centrifugal compressor; A scroll section that forms a scroll flow path of the centrifugal compressor, When defining the flow path width of the diffuser flow path along the axial direction of the centrifugal compressor as Ta, and defining the shortest distance from the starting end position, which is the connection position between the inner circumferential surface of the scroll section and the hub side flow path surface of the diffuser flow path, to the imaginary circular arc tangent to the end position, which is the position on the inner circumferential surface opposite to the starting end position, as Tb, and defining the angular position around the scroll center in the scroll flow path such that the confluence position of the start and end of the winding of the scroll flow path is set to 60 degrees and the angle gradually increases towards the downstream side of the scroll flow path, In the range where the angular position is from 180 degrees to 360 degrees, the relationship Tb / Ta≥1.0 is satisfied, When defining the length along the axial direction of the centrifugal compressor between the end position and the downstream end of the shroud side flow path surface of the diffuser flow path at the position where the angular position is θ1 as T1, and defining the length along the axial direction between the end position and the downstream end of the shroud side flow path surface at the position where the angular position is θ2, which is larger than θ1, as T2, The relationship T1<T2 is satisfied.

2. The volute according to claim 1, In the range where the angular position is from 60 degrees to 180 degrees, the relationship Tb / Ta≥0.5 is satisfied.

3. The volute according to claim 1, In the range where the angular position is from 180 degrees to 360 degrees, the relationship Tb / Ta≤1.75 is satisfied.

4. The volute according to claim 1, When defining the crossing angle between the imaginary tangent line tangent to the end position on the inner circumferential surface of the scroll section and the radial direction of the centrifugal compressor as α, In the range where the angular position is from 180 degrees to 360 degrees, the relationship α≤50° is satisfied.

5. The volute according to claim 4, In the range where the angular position is from 60 degrees to 180 degrees, the relationship α≤70° is satisfied.

6. A volute, which is the volute of a centrifugal compressor, is characterized in that, Comprising: A diffuser section that forms a diffuser flow path of the centrifugal compressor; A scroll section that forms a scroll flow path of the centrifugal compressor; When defining the crossing angle between the imaginary tangent line tangent to the end position, which is the position opposite to the starting end position, on the inner circumferential surface of the scroll section and the radial direction of the centrifugal compressor as α, and defining the angular position around the scroll center in the scroll flow path such that the confluence position of the start and end of the winding of the scroll flow path is set to 60 degrees and the angle gradually increases towards the downstream side of the scroll flow path, In the range where the angular position is from 180 degrees to 360 degrees, the relationship α≤50° is satisfied, When the length along the axial direction of the centrifugal compressor from the terminal position at the position where the angular position is θ1 to the downstream end of the shroud side flow surface of the diffusion flow path is defined as T1, and the length along the axial direction from the terminal position at the position where the angular position is θ2 which is larger than θ1 to the downstream end of the shroud side flow surface is defined as T2, the relationship of T1 < T2 is satisfied.

7. The volute according to claim 6, in the range where the angular position is from 60 degrees to 180 degrees, the relationship of α ≤ 70° is satisfied.

8. The volute according to any one of claims 1 to 7, when the length along the radial direction of the centrifugal compressor from the axis to the downstream end of the shroud side flow surface of the diffusion flow path at the position where the angular position is θ3 is defined as d1, and the length along the radial direction from the axis to the downstream end of the shroud side flow surface at the position where the angular position is θ4 which is larger than θ3 is defined as d2, the relationship of d1 > d2 is satisfied.

9. A centrifugal compressor, comprising the volute according to any one of claims 1 to 8.

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