Compressor casing and centrifugal compressor

Abstract

The compressor casing has: a cover surface; a front side inner peripheral surface formed on the front side in the axial direction of the cover surface and located on the outer side in the radial direction compared with the front end of the cover surface; at least one protrusion protruding from the front side inner peripheral surface toward the inner side in the radial direction; a rear end of the at least one protrusion configured to be connected to the front end of the cover surface, the at least one protrusion being provided in a plate shape and having an inclined leading edge extending obliquely with respect to the axis of the impeller from the front end of the protrusion toward the rear side when sectioned along the axis of the impeller.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a compressor casing for rotatably housing an impeller of a centrifugal compressor, and a centrifugal compressor provided with the compressor casing. BACKGROUND

[0002] A centrifugal compressor used in a compressor section of a vehicle or a marine turbocharger and the like discharges fluid (for example, air) to the outer side in the radial direction by applying kinetic energy to the fluid by rotation of an impeller, and obtains a pressure rise of the fluid by centrifugal force. In this centrifugal compressor, it is required to achieve a high pressure ratio and high efficiency in a wide operating range, and various efforts have been made for this.

[0003] For example, at a low flow rate at which the suction flow rate of the centrifugal compressor is small, an unstable phenomenon called surge in which the fluid violently vibrates in the flow direction of the fluid occurs. If surge occurs, reverse flow in which the flow of air introduced from the intake port flows in the opposite direction occurs near the shroud surface, and due to this reverse flow, the efficiency of the centrifugal compressor is reduced.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT DOCUMENTS

[0006] Patent Document 1: Japanese Patent No. 6279524 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] In Patent Document 1, a scheme is disclosed in which the above-mentioned reverse flow is guided to the inner side in the radial direction by a plate-shaped protruding portion, and the air flowing toward the impeller side is pressurized, thereby suppressing the reverse flow.

[0009] In order to achieve high efficiency of the centrifugal compressor, it is necessary to suppress the pressure loss of the working fluid flowing in the compressor casing as much as possible.

[0010] In view of the above, an object of at least one embodiment of the present disclosure is to provide a compressor casing capable of improving the efficiency of a centrifugal compressor, and a centrifugal compressor provided with the compressor casing.

[0011] TECHNICAL SOLUTION FOR SOLVING THE PROBLEMS

[0012] The compressor casing of the present disclosure is a compressor casing for rotatably housing an impeller of a centrifugal compressor, characterized by comprising:

[0013] a shroud surface including a surface opposed to a leading end of an impeller blade of the impeller with a prescribed gap;

[0014] a front side inner peripheral surface formed on the front side in the axial direction of the cover and located radially outward from the front end of the cover;

[0015] at least one protrusion protruding from the front side inner peripheral surface toward the inner side in the radial direction;

[0016] a rear end of the at least one protrusion is connected to the front end of the cover,

[0017] the at least one protrusion is provided in a plate shape and has an inclined leading edge that extends obliquely with respect to the axis of the impeller from the front end of the protrusion toward the rear side in a cross-sectional view along the axis of the impeller.

[0018] The centrifugal compressor of the present disclosure is provided with the compressor casing.

[0019] Effects of the Invention

[0020] According to at least one embodiment of the present disclosure, it is possible to provide a compressor casing that improves the efficiency of a centrifugal compressor and a centrifugal compressor provided with the compressor casing. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is an explanatory diagram for explaining the configuration of a turbocharger provided with the centrifugal compressor of one embodiment.

[0022] Figure 2 is a schematic cross-sectional view schematically showing the compressor side of the turbocharger provided with the centrifugal compressor of one embodiment, and is a schematic cross-sectional view including the axis of the centrifugal compressor.

[0023] Figure 3 is an explanatory diagram for explaining the compressor casing of the first embodiment.

[0024] Figure 4 is a schematic cross-sectional view schematically showing the A-B line section in Figure 3

[0025] Figure 5 is an explanatory diagram for explaining a modification example of the compressor casing of the first embodiment.

[0026] Figure 6 is an explanatory diagram for explaining a modification example of the compressor casing of the first embodiment.

[0027] Figure 7 is an explanatory diagram for explaining the compressor casing of the second embodiment.

[0028] Figure 8 is an explanatory diagram for explaining a modification example of the compressor casing of the second embodiment.​

[0029] Figure 9 is a explanatory view for explaining a modification example of the compressor casing of the second embodiment.

[0030] Figure 10 is a explanatory view for explaining the compressor casing of the third embodiment.

[0031] Figure 11 is a schematic view schematically showing a state in the vicinity of the pinch surface of the compressor casing shown in FIG. 8 from the rear side in the axial direction. Figure 10 DETAILED DESCRIPTION

[0032] Hereinafter, several embodiments of the present disclosure will be described with reference to the drawings. Note that the size, material, shape, relative arrangement, and the like of the constituent components described as the embodiments or shown in the drawings are not intended to limit the scope of the present disclosure to them, but are mere illustrative examples.

[0033] For example, expressions such as "a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric", or "coaxial" indicating relative or absolute arrangement do not strictly indicate such an arrangement, but also indicate a state of relative displacement with a tolerance or an angle or a distance that can achieve the same degree of function.

[0034] For example, expressions such as "the same", "equal", and "homogeneous" indicating the equal state of things do not only indicate a strictly equal state, but also indicate a state in which there is a difference within a tolerance or a difference that can achieve the same degree of function.

[0035] For example, expressions such as "quadrilateral shape" or "cylindrical shape" indicating shape do not only indicate a geometrically strict quadrilateral shape or a cylindrical shape, but also include shapes with a concave-convex portion or a chamfer portion within a range in which the same effect can be obtained.

[0036] In addition, expressions such as "provided with", "including", and "having" one constituent element are not exclusive expressions that exclude the existence of other constituent elements.

[0037] Note that the same reference signs are assigned to the same constituent components, and the description is omitted.

[0038] (Centrifugal compressor, turbocharger)

[0039] Figure 1 is a explanatory view for explaining the configuration of the turbocharger provided with the centrifugal compressor of one embodiment. Figure 2 is a schematic cross-sectional view schematically showing the compressor side of the turbocharger provided with the centrifugal compressor of one embodiment, and is a schematic cross-sectional view including the axis of the centrifugal compressor. ​

[0040] The centrifugal compressor 1 of several embodiments of the present disclosure has a Figure 1 , Figure 2 impeller 2 and a compressor casing 3 that rotatably houses the impeller 2.

[0041] The centrifugal compressor 1 can be applied, for example, to a turbocharger 10 for a motor vehicle, a ship, or power generation, or other industrial centrifugal compressors, blowers, and the like. In the illustrated embodiment, the centrifugal compressor 1 is mounted on the turbocharger 10. The turbocharger 10 has, as shown in Figure 1

[0042] In the illustrated embodiment, as shown in Figure 1 , the turbocharger 10 further has a bearing 15 that rotatably supports the rotating shaft 12, and a bearing casing 16 that houses the bearing 15. The bearing casing 16 is disposed between the compressor casing 3 and the turbine casing 14, and is mechanically connected to the compressor casing 3 and the turbine casing 14 with a connecting member (e.g., a connecting bolt or the like).

[0043] Hereinafter, for example, as shown in Figure 1 , the axis CA of the centrifugal compressor 1, i.e., the direction in which the axis of the impeller 2 extends, is defined as the axial direction X, and the direction orthogonal to the axis CA is defined as the radial direction Y. The upstream side in the axial direction X, i.e., the side (left side in the drawing) on which the intake port 31 is located with respect to the impeller 2, in the intake direction (main flow direction) of the centrifugal compressor 1 is defined as the front side XF. Also, the opposite side of the front side XF in the axial direction X, i.e., the downstream side (right side in the drawing) in the intake direction of the centrifugal compressor 1 is defined as the rear side XR.

[0044] In the illustrated embodiment, as shown in Figure 1 , the compressor casing 3 is formed with an intake port 31 for introducing fluid (e.g., air) from the outside to the inside of the compressor casing 3, and a discharge port 32 for discharging fluid that has passed through the impeller 2 to the outside of the compressor casing 3. The turbine casing 14 is formed with a turbine-side inlet port 141 for introducing working fluid (e.g., exhaust gas) that rotates the turbine rotor 13 from the outside to the inside of the turbine casing 14, and a turbine-side discharge port 142 for discharging working fluid that has passed through the turbine rotor 13 to the outside of the turbine casing 14.

[0045] As shown in Figure 1 ​As shown, the rotating shaft 12 has a length direction along the axial direction X. The impeller 2 is mechanically connected to one side of the rotating shaft 12 in the length direction (front side XF), and the turbine rotor 13 is mechanically connected to the other side of the rotating shaft 12 in the length direction (rear side XR).

[0046] The turbocharger 10 uses a working fluid introduced into the interior of the turbine housing 14 through the turbine-side inlet 141 to rotate the turbine rotor 13. Examples of this working fluid include exhaust gas generated by an exhaust gas generating device (e.g., an internal combustion engine such as an engine), which is not shown in the figure. The impeller 2 is mechanically connected to the turbine rotor 13 via a rotating shaft 12, and thus rotates in conjunction with the rotation of the turbine rotor 13. The turbocharger 10 compresses the fluid introduced into the interior of the compressor housing 3 through the intake port 31 by rotating the impeller 2, and delivers it to the object to which the compressed fluid is supplied (e.g., an internal combustion engine such as an engine) through the outlet 32.

[0047] (impeller)

[0048] like Figure 2 As shown, the impeller 2 includes a hub 21 and a plurality of impeller blades 23 disposed on the outer surface 22 of the hub 21. The hub 21 is mechanically fixed to one side of the rotating shaft 12, and thus the hub 21 and the plurality of impeller blades 23 are supported so as to be able to rotate integrally with the rotating shaft 12 about the axis CA of the impeller 2. The impeller 2 is configured to be housed in the compressor housing 3 and to guide fluid introduced from the forward side XF in the axial direction X to the outward side in the radial direction Y.

[0049] In the illustrated embodiment, the outer surface 22 of the hub 21 is formed in a concave-bending shape, with the distance from the axis CA of the impeller 2 increasing as it moves from the front side XF toward the rear side XR. Each of the plurality of impeller blades 23 is spaced apart from each other in the circumferential direction about the axis CA. The shroud 4 includes a convex-bending surface 41 formed with the distance from the axis CA of the impeller 2 increasing as it moves from the front side XF toward the rear side XR. The tip (blade-side end) 24 of the impeller blade 23 is located on the opposite side of the connection portion (hub-side end) of the outer surface 22 of the hub 21. A gap G (void) is formed between the surfaces 41 that are convexly curved in a manner opposite to the tip 24.

[0050] (Compressor casing)

[0051] In the illustrated implementation, such as Figure 2 As shown, the compressor housing 3 includes a cover portion 33 including the aforementioned cover surface 4, an intake inlet portion 34 forming an intake inlet passage 50 for the centrifugal compressor 1, a diffuser portion 35 forming a diffuser flow passage 60 for the centrifugal compressor 1, and a vortex portion 36 forming a vortex flow passage 360 ​​for the centrifugal compressor 1.

[0052] The suction gas introduction passage 50 is a flow passage for guiding the suction gas (e.g., air or the like) introduced from the suction port 31 of the compressor casing 3 toward the impeller blades 23. The diffuser passage 60 is a flow passage for guiding the fluid that has passed through the impeller 2 toward the scroll-shaped scroll passage 360 provided around the impeller 2. The scroll passage 360 is a flow passage for guiding the fluid that has passed through the impeller 2 and the diffuser passage 60 toward the outside of the compressor casing 3 through the discharge port 32 (see Figure 1 ).

[0053] The suction gas introduction passage 50 and the scroll passage 360 are formed in the inside of the compressor casing 3, respectively. The suction gas introduction portion 34 has a front side inner peripheral surface 5 that forms the suction gas introduction passage 50. The front side inner peripheral surface 5 is formed on the front side XF in the axial direction of the cover surface 4 and is located on the outer side in the radial direction Y compared to the front end 42 (front side XF end) of the cover surface 4. Also, the above-mentioned suction port 31 is formed on the front end of the suction gas introduction portion 34.

[0054] The scroll passage 360 is formed so as to surround the periphery of the impeller 2 housed in the compressor casing 3 on the outer side in the radial direction Y with respect to the impeller 2. The scroll portion 36 has a flow passage wall surface 361 that forms the scroll passage 360.

[0055] Also, in the illustrated embodiment, as shown in Figure 2 , the compressor casing 3 forms the above-mentioned diffuser passage 60 by being combined with other components (in the illustrated example, the bearing casing 16). The diffuser passage 60 is formed by the diffuser surface 6 and the surface 161 of the bearing casing 16 that opposes the diffuser surface 6. Further, in some other embodiments, the diffuser passage 60 can be formed in the inside of the compressor casing 3.

[0056] The above-mentioned cover portion 33 is provided between the suction gas introduction portion 34 and the diffuser portion 35. The outlet of the suction gas introduction passage 50 communicates with the inlet of the diffuser passage 60, and the outlet of the diffuser passage 60 communicates with the inlet of the scroll passage 360. The fluid introduced into the inside of the compressor casing 3 through the suction port 31 is transported to the impeller 2 after flowing toward the rear side XR in the suction gas introduction passage 50. The fluid transported to the impeller 2 is discharged to the outside of the compressor casing 3 after sequentially flowing through the diffuser passage 60 and the scroll passage 360 from the discharge port 32 (see Figure 1 ).

[0057] At a low flow rate at which the flow rate of the suction gas (the flow rate of the main flow MF that flows into the suction gas introduction passage 50 through the suction port 31 and flows toward the impeller 2) of the centrifugal compressor 1 is small, an unstable phenomenon called surging in which the fluid violently vibrates in the flow direction of the fluid can occur. If surging occurs, a reverse flow RF that flows in the opposite direction to the main flow MF, i.e., toward the front side XF in the axial direction X, can occur near the cover surface 4, and there is a possibility that the efficiency of the centrifugal compressor 1 will decrease.

[0058] Figure 3 This is an explanatory diagram used to illustrate the compressor housing of the first embodiment. Figure 4 It is a schematic representation Figure 3 A schematic cross-sectional view of the AB line section in the diagram.

[0059] like Figure 3 As shown, in some embodiments, the compressor housing 3 includes: a shroud 4, which includes a surface 41 that is opposite to the front end 24 of the impeller blade 23 of the impeller 2 with a predetermined gap G; a front side inner peripheral surface 5, which is formed on the front side XF in the axial direction of the shroud 4 and is located on the outer side in the radial Y direction compared with the front end 42 of the shroud 4; and at least one protrusion 7 that protrudes from the front side inner peripheral surface 5 toward the inner side in the radial Y direction.

[0060] The rear end 71 (rear XR end) of the protrusion 7 is configured to connect with the front end 42 of the cover 4. The protrusion 7 has... Figure 3 In the cross-sectional view shown along the axis CA of the impeller 2, the inclined leading edge 73 extends obliquely from the front end 72 of the protrusion 7 toward the rear side XR relative to the axis CA of the impeller 2.

[0061] like Figure 4 As shown, the protrusion 7 is formed in a plate shape. In the illustrated embodiment, the protrusion 7 has a first surface 75 and a second surface 76 located downstream of the impeller 2 in the rotational direction RD compared to the first surface 75. The first surface 75 and the second surface 76 extend along the axial direction X and radial direction Y of the impeller 2, respectively. It should be noted that, as shown, at least one protrusion 7 may include a plurality of protrusions 7 arranged with circumferential spacing (two in the illustrated example)

[0062] According to the above configuration, the compressor housing 3 has at least one protrusion 7 that protrudes radially inward from the inner peripheral surface 5 on the front side. As described above, at low flow rates with low intake flow of the centrifugal compressor 1, a backflow RF is generated near the shroud 4. The backflow RF is given a rotational direction component pointing in the rotation direction RD of the impeller 2 due to the rotation of the impeller 2, and thus has a strong centrifugal effect. The backflow RF with such centrifugal effect flows along the inner peripheral surface 5 on the front side while rotating in the rotation direction RD and collides with the protrusion 7 (first surface 75). By causing the backflow RF to collide with the protrusion 7, the backflow RF can be suppressed. The protrusion 7 is positioned near the leading edge 25 of the impeller 2 in the axial X direction, which has a high effect on suppressing the backflow RF. According to the above configuration, since the rear end 71 of the protrusion 7 is connected to the front end 42 of the shroud 4, the protrusion 7 is located near the leading edge 25 in the axial X direction, which can effectively suppress the backflow RF. By suppressing the aforementioned backflow RF, the surge flow in the low-flow-side working region can be reduced, thereby improving the efficiency of the centrifugal compressor 1.

[0063] Furthermore, according to the above configuration, the protrusion 7 is plate-shaped and has an inclined leading edge 73 that extends obliquely from the front end 72 of the protrusion 7 toward the rearward side XR relative to the axis CA of the impeller 2 in a cross-sectional view along the axis CA of the impeller 2. In this case, compared to the case where the leading edge 73A of the protrusion 7 extends in a direction orthogonal to the axis CA of the impeller 2, it is less likely to obstruct the flow of the mainstream MF introduced into the impeller 2, and thus collision loss of the mainstream MF caused by collision with the protrusion 7 can be suppressed. As a result, pressure loss of the mainstream MF introduced into the impeller 2 (especially pressure loss in the high-flow-rate working area) can be effectively suppressed, thereby improving the efficiency of the centrifugal compressor 1.

[0064] In some implementations, such as Figure 3 As shown, the aforementioned protrusion 7 has an inner edge 74 extending from the rear end of the inclined leading edge 73 toward the rearward side XR and connecting with the front end 42 of the cover 4. The inner edge 74 is located on the outer side in the radial Y direction compared to the front end 24A on the leading edge 25 of the impeller 2. Such a protrusion 7 with an inner edge 74 can suppress the collision between the mainstream MF flowing in the radial Y direction of the intake guide passage 50 and the protrusion 7, and can effectively suppress the pressure loss of the mainstream MF introduced into the impeller 2.

[0065] Figure 5 This is an explanatory diagram used to illustrate a modified example of the compressor housing of the first embodiment.

[0066] In some implementations, such as Figure 3 , Figure 5 As shown, the aforementioned front inner circumferential surface 5 includes a conical surface 51 that expands in diameter from the front end 42 of the aforementioned cover surface 4 towards the front XF, and an axial surface 53 that extends from the front end 52 of the conical surface 51 towards the front XF along the axial direction X. The aforementioned protrusion 7 extends at least throughout the entire axial direction X of the conical surface 51.

[0067] exist Figure 3 In the illustrated embodiment, the protrusion 7 is provided on both the conical surface 51 and the axial surface 53. Figure 5 In the embodiment shown, the protrusion 7 is provided only on the conical surface 51 in the inner peripheral surface 5 on the front side.

[0068] According to the above configuration, the inner peripheral surface 5 on the front side of the compressor housing 3 includes a conical surface 51 that expands in diameter from the front end 42 of the shroud 4 toward the front side XF, thereby suppressing the loss due to the sharp contraction of the mainstream airflow MF introduced into the impeller 2. A counterflow RF having a rotational direction component pointing toward the rotational direction RD of the impeller 2 flows along the conical surface 51 toward the front side XF. The aforementioned protrusion 7 extends at least throughout the entire axial direction X of the conical surface 51, thus effectively suppressing the counterflow RF flowing along the conical surface 51.

[0069] In some implementations, such asFigure 5 As shown, the aforementioned protrusion 7 is only provided on the conical surface 51 in the inner peripheral surface 5 on the front side. In this case, the counterflow RF, which has a rotational direction component pointing towards the impeller 2, flows along the conical surface 51 on the front side XF. By providing the aforementioned protrusion 7 on the conical surface 51, the counterflow RF flowing along the conical surface 51 can be effectively suppressed. Furthermore, by providing the aforementioned protrusion 7 only on the conical surface 51 on the inner peripheral surface 5 on the front side, that is, not on the axial surface 53 in the inner peripheral surface 5 on the front side, the collision loss of the main flow MF caused by the collision with the protrusion 7 can be suppressed.

[0070] In some embodiments, the aforementioned protrusion 7 is along... Figure 3 , Figure 5 In the cross-sectional view of the axis CA of the impeller 2 shown, the length L parallel to the axis of the protrusion 7 changes in the radial direction. A counterflow RF, having a rotational component pointing towards the rotational direction RD of the impeller 2, flows forward XF along the conical surface 51. In this case, by appropriately positioning the protrusion 7 within a suitable range to suppress the counterflow RF flowing along the conical surface 51, collision losses of the main flow MF caused by collisions with the protrusion 7 can be suppressed, and the counterflow RF can be effectively suppressed.

[0071] exist Figure 3 , Figure 5 In the illustrated embodiment, the length L is configured to increase as it moves outward in the radial direction. In this case, collision loss of the main MF caused by collision with the protrusion 7 can be effectively suppressed.

[0072] Figure 6 This is an explanatory diagram used to illustrate a modified example of the compressor housing according to the first embodiment. In some embodiments, the compressor housing 3 may include a protrusion 7 with a length L constant in the radial direction. That is, in some embodiments, the protrusion 7... Figure 6 In the cross-sectional view shown along the axis CA of the impeller 2, the length L parallel to the axis of the protrusion 7 is constant in the radial direction.

[0073] Figure 7 This is an explanatory diagram used to illustrate the compressor housing of the second embodiment. Figure 8 and Figure 9 These are explanatory diagrams used to illustrate a modified example of the compressor housing in the second embodiment. Figure 7 The diagram schematically shows the state of the compressor housing 3's cover 4 and front inner circumferential surface 5 as viewed from the radial inner side of the impeller 2.

[0074] like Figure 3 , Figure 5 , Figure 8 , Figure 9As shown, in some embodiments, the compressor housing 3 includes: a shroud 4, which includes a surface 41 that faces the impeller blade 23 of the impeller 2 with a predetermined gap G; a front-side inner peripheral surface 5, which is formed on the axial front side XF of the shroud 4 and is located radially outward compared to the front end 42 of the shroud 4; and at least one protrusion 7 that protrudes radially inward from the front-side inner peripheral surface 5. Figure 7 As shown, the protrusion 7 is formed in the shape of a plate, and the rear end 71 of the protrusion 7 is configured to be located upstream of the front end 72 of the protrusion 7 in the rotation direction RD of the impeller 2.

[0075] It should be noted that in the above embodiments, the rear end 71 of the protrusion 7 is configured to be located at the same position in the rotation direction RD of the impeller 2 relative to the front end 72 of the protrusion 7.

[0076] In the illustrated embodiment, the rear end 71 of the protrusion 7 is configured to connect with the front end 42 of the cover 4. The protrusion 7 is configured to form a straight line from the front end 72 to the rear end 71.

[0077] According to the above configuration, the rear end 71 of the protrusion 7 is positioned upstream of the impeller 2 in the rotation direction RD compared to the front end 72 of the protrusion. Therefore, the protrusion 7 can pre-apply rotation to the mainstream MF introduced into the impeller 2 along the inner circumferential surface 5 of the front side in a direction opposite to the rotation direction RD of the impeller 2. By pre-applying this rotation to the mainstream MF, the relative inflow velocity of the mainstream MF introduced into the impeller 2 can be increased. By increasing the relative inflow velocity of the mainstream MF, the surge flow in the low-flow-side operating region can be reduced, thereby improving the efficiency of the centrifugal compressor 1.

[0078] It should be noted that this embodiment can be combined with the above-described embodiments, or it can be implemented independently. For example, it can be relative to... Figure 3 , Figure 5 The protrusion 7 with the inclined leading edge 73 shown in this embodiment can also be applied relative to... Figure 8 , Figure 9 The protrusion 7 shown has a leading edge 73A extending radially inward from the front end 72 of the protrusion 7 to the inner side. This embodiment applies.

[0079] In some implementations, such as Figure 3 , Figure 5 As shown, the protrusion 7 is integrally formed with the front side inner peripheral surface 5 (e.g., conical surface 51) by cutting or casting.

[0080] According to the above configuration, the protrusion 7 is integrally formed with the front side inner circumferential surface 5 by machining or casting. In this case, compared with the case where the protrusion 7, which is separately manufactured with the front side inner circumferential surface 5, is fixed to the front side inner circumferential surface 5 by welding or bolting, the surface roughness of the front side inner circumferential surface 5 can be improved. By improving the surface roughness of the front side inner circumferential surface 5, the pressure loss of the mainstream MF introduced into the impeller 2 can be reduced.

[0081] It should be noted that in some implementation methods, such as Figure 8 , Figure 9 As shown, the protrusion 7 can be manufactured separately from the front side inner peripheral surface 5.

[0082] In the above embodiments, the protrusion 7 is provided on the upstream side of the impeller 2. However, by providing such a protrusion 7 on the downstream side of the impeller 2, the backflow on the downstream side of the impeller 2 can be suppressed, thereby improving the efficiency of the centrifugal compressor 1.

[0083] Figure 10 This is an explanatory diagram used to illustrate the compressor housing of the third embodiment. Figure 11 This is a schematic representation of the view from the rear side along the axial direction. Figure 10 A schematic diagram of the area near the compression surface of the compressor housing.

[0084] like Figure 10 As shown, in some embodiments, the compressor housing 3 includes: a shroud 4, which includes a surface 41 that faces the impeller blade 23 of the impeller 2 with a predetermined gap G; a diffuser surface 6, which is located axially on the back side 26 (back side XR) of the impeller 2 compared to the rear end 43 of the shroud 4, and includes a radial surface 61 extending along the radial direction Y and a constricting surface 63 connecting the inner end 62 of the radial surface 61 to the rear end 43 of the shroud 4; and at least one diffuser-side protrusion 8 that protrudes from the constricting surface 63 toward the axially positioned back side 26 (back side XR) of the impeller 2.

[0085] The diffuser-side protrusion 8 is located on the hub surface 22A side (front side XF) of the impeller 2 in the axial direction compared to the radial surface 61. The inner end 81 of the diffuser-side protrusion 8 is connected to the rear end 43 of the cover surface 4.

[0086] In the illustrated embodiment, the diffuser side protrusion 8 has a... Figure 10 In the cross-sectional view along the axis CA of the impeller 2 shown, there is a diffuser-side inclined leading edge 82 that extends obliquely to the rearward side XR from the inner end 81 of the diffuser-side protrusion 8 and relative to the axis CA of the impeller 2, and a rearward side edge 83 that extends outward radially Y from the outer end of the diffuser-side inclined leading edge 82 and whose outer end 84 is connected to the inner end 62 of the radial surface 61.

[0087] like Figure 11As shown, the diffuser side protrusion 8 is formed in a plate shape. In the illustrated embodiment, the diffuser side protrusion 8 has a first surface 85 and a second surface 86 located downstream of the impeller 2 in the rotational direction RD compared to the first surface 85. The first surface 85 and the second surface 86 extend along the axial direction X and radial direction Y of the impeller 2, respectively. It should be noted that, as shown, at least one diffuser side protrusion 8 may include a plurality of diffuser side protrusions 8 arranged with circumferential spacing (two in the illustrated example).

[0088] According to the above configuration, the compressor housing 3 has at least one diffuser-side protrusion 8 protruding from the contraction surface 63 toward the rear side 26 (rear side XR) of the impeller 2 in the axial direction. This diffuser-side protrusion 8 suppresses the backflow RF2, which has a rotational direction component pointing toward the rotational direction RD of the impeller 2, generated near the contraction surface 63. This suppresses the rotational pressure loss of the mainstream MF located downstream of the impeller 2. By suppressing the backflow RF2, rotational stall at the inlet of the diffuser path 60 in the low-flow-side operating region can be suppressed, thereby improving the efficiency of the centrifugal compressor 1.

[0089] The impeller 2 in the centrifugal compressor 1 is located downstream, resulting in a non-uniform velocity distribution. The aforementioned diffuser-side protrusion 8 acts as a vortex simulator to suppress boundary layer stripping. Therefore, the efficiency of the centrifugal compressor 1 can be improved not only when rotational stall occurs at the inlet of the diffuser flow path 60, but also at the normal operating point of the centrifugal compressor 1.

[0090] It should be noted that this embodiment can be combined with the above-described embodiments or implemented independently. For example, the compressor housing 3 can have the above-described protrusion 7 and the above-described diffuser-side protrusion 8. In this case, rotational stall at the upstream and downstream sides of the impeller 2 can be suppressed, and thus, due to the superimposed effect of the protrusion 7 and the diffuser-side protrusion 8, the efficiency of the centrifugal compressor 1 can be effectively improved.

[0091] In some implementations, such as Figure 10 As shown, the aforementioned diffuser side protrusion 8 is integrally formed with the aforementioned diffuser surface 6 (e.g., shrinkage surface 63) by cutting or casting.

[0092] According to the above configuration, the diffuser side protrusion 8 is integrally formed with the diffuser surface 6 by machining or casting. In this case, compared with the case where the diffuser side protrusion 8, which is manufactured separately from the diffuser surface 6, is fixed to the diffuser surface 6 by welding or bolting, the surface roughness of the diffuser surface 6 can be improved. By improving the surface roughness of the diffuser surface 6, the pressure loss of the main flow current MF after passing through the impeller 2 can be reduced.

[0093] It should be noted that, in some other embodiments, the aforementioned diffuser side protrusion 8 may be manufactured separately from the aforementioned diffuser surface 6.

[0094] Centrifugal compressor 1 in some embodiments, such as Figure 1 , Figure 2 As shown, the compressor housing 3 described above is provided. In this case, the pressure loss of the working fluid flowing inside the compressor housing 3 can be effectively suppressed, thereby improving the efficiency of the centrifugal compressor 1.

[0095] This disclosure is not limited to the above-described embodiments, but includes embodiments that are modified based on the above-described embodiments and embodiments that appropriately combine these embodiments.

[0096] The content described in the above embodiments can be understood, for example, as follows.

[0097] 1) The compressor housing (3) of at least one embodiment of the present disclosure is a compressor housing for rotatably housing the impeller (2) of the centrifugal compressor (1), and includes:

[0098] The cover (4) includes a surface (41) that is opposite to the front end (24) of the impeller blade (23) of the impeller with a predetermined gap (G);

[0099] The front inner circumferential surface (5) is formed on the front side of the cover (4) in the axial direction and is located on the outer side in the radial direction compared with the front end (42) of the cover (4);

[0100] At least one protrusion (7) protrudes from the inner peripheral surface (5) on the front side toward the radially inner side;

[0101] The rear end (71) of the at least one protrusion (7) is configured to connect with the front end (42) of the cover (4).

[0102] The at least one protrusion (7) is plate-shaped and has an inclined leading edge (73) that extends obliquely from the front end (72) of the protrusion (7) toward the rearward side relative to the axis of the impeller in a cross-sectional view along the axis (CA) of the impeller (2).

[0103] According to configuration 1) above, the compressor housing has at least one protrusion projecting radially inward from the inner circumference of the front side. By causing the backflow to collide with the protrusion, backflow can be suppressed. The protrusion's placement near the leading edge of the impeller further enhances its backflow suppression effect. According to configuration 1) above, the rear end of the protrusion is connected to the front end of the casing, thus placing the protrusion near the leading edge axially, effectively suppressing backflow. By suppressing the backflow, surge flow in the low-flow-side operating region can be reduced, thereby improving the efficiency of the centrifugal compressor.

[0104] Furthermore, according to the configuration described in 1) above, the protrusion is plate-shaped and has an inclined leading edge that extends obliquely from the front end of the protrusion toward the rearward side relative to the impeller axis in a cross-sectional view along the impeller axis. In this case, compared to the case where the leading edge of the protrusion extends in a direction orthogonal to the impeller axis, it is less likely to obstruct the mainstream flow introduced into the impeller, thus suppressing the collision loss of the mainstream caused by collision with the protrusion. As a result, the pressure loss of the mainstream introduced into the impeller (especially the pressure loss in the high-flow-rate working region) can be effectively suppressed, thereby improving the efficiency of the centrifugal compressor.

[0105] 2) In some embodiments, based on the compressor housing (3) described in 1) above,

[0106] The front inner circumferential surface (5) includes a tapered surface (51) that expands in diameter from the front end (42) of the cover (4) toward the front side and an axial surface (53) that extends axially from the front end (52) of the tapered surface (51) toward the front side.

[0107] The at least one protrusion (7) extends at least throughout the entire axial extension of the conical surface (51).

[0108] According to configuration 2) above, the inner circumferential surface of the compressor housing on the front side includes a conical surface that expands in diameter from the front end of the shroud to the front side, thereby suppressing the sharp contraction loss of the mainstream airflow introduced into the impeller. A counterflow with a rotational component pointing in the direction of impeller rotation flows along the conical surface to the front side. The aforementioned protrusion extends at least throughout the entire axial direction of the conical surface, thus effectively suppressing the counterflow flowing along the conical surface.

[0109] 3) In some embodiments, based on the compressor housing (3) described in 2) above,

[0110] In a cross-sectional view along the axis of the impeller, the length (L) of the at least one protrusion (7) parallel to the axis varies in the radial direction.

[0111] According to the configuration described in 3) above, in a cross-sectional view along the impeller axis, the length of the protrusion parallel to the axis varies radially. The counterflow flows forward along the conical surface. In this case, by appropriately configuring the protrusion within a suitable range to suppress the counterflow flowing along the conical surface, it is possible to suppress the collision loss of the main flow caused by collisions with the protrusion, and to effectively suppress the counterflow.

[0112] 4) In some embodiments, based on the compressor housing (3) described in any one of 1) to 3) above,

[0113] The at least one protrusion (7) is configured such that the rear end (71) of the protrusion is located upstream of the impeller in the direction of rotation (RD) compared to the front end (72) of the protrusion.

[0114] According to the configuration in 4) above, the rear end of the protrusion is positioned upstream of the impeller in the direction of rotation compared to the front end of the protrusion. Therefore, the protrusion allows for pre-rotation of the mainstream flow introduced into the impeller along the inner circumference of the front side in the opposite direction to the impeller's rotation. By pre-applying this rotation to the mainstream flow, the relative inflow velocity of the mainstream flow introduced into the impeller can be increased. By increasing the relative inflow velocity of the mainstream flow, the surge flow in the low-flow-side operating region can be reduced, thereby improving the efficiency of the centrifugal compressor.

[0115] 5) In some embodiments, based on the compressor housing (3) described in any one of 1) to 4) above,

[0116] The at least one protrusion (7) is integrally formed with the front side inner peripheral surface (5) by cutting or casting.

[0117] According to the configuration described in 5) above, the protrusion is integrally formed with the front side inner circumferential surface by machining or casting. In this case, compared to the case where the protrusion, which is manufactured separately from the front side inner circumferential surface, is fixed to the front side inner circumferential surface by welding or bolting, the surface roughness of the front side inner circumferential surface can be improved. By improving the surface roughness of the front side inner circumferential surface, the pressure loss of the main flow introduced into the impeller can be reduced.

[0118] 6) In some embodiments, based on the compressor housing (3) described in any one of 1) to 5) above,

[0119] The front inner circumferential surface (5) includes a conical surface (51) that expands in diameter from the front end of the cover towards the front side and an axial surface (52) that extends axially from the front end of the conical surface towards the front side.

[0120] The at least one protrusion (7) is provided only on the conical surface (51) on the inner circumferential surface (5) of the front side.

[0121] According to the configuration described in 6) above, the counterflow flows along the conical surface on the front side. By providing the aforementioned protrusion on the conical surface, the counterflow flowing along the conical surface can be effectively suppressed. Furthermore, by providing the aforementioned protrusion only on the conical surface of the inner circumferential surface of the front side, that is, not providing the protrusion on the axial surface of the inner circumferential surface of the front side, the collision loss of the main flow caused by collision with the protrusion can be suppressed.

[0122] 7) In some embodiments, based on the compressor housing (3) described in any one of 1) to 6) above, it further comprises:

[0123] The diffuser surface (6) is located axially on the back side (26) of the impeller (2) compared to the rear end (43) of the cover surface (4), and includes a radial surface (61) extending along the radial direction and a tightening surface (63) connecting the inner end (62) of the radial surface (61) to the rear end (43) of the cover surface (4);

[0124] At least one diffuser-side protrusion (8) protrudes from the tightening surface (63) toward the back (26) side of the impeller (2) in the axial direction;

[0125] The at least one diffuser-side protrusion (8) is located on the hub surface (22A) side of the impeller (2) in the axial direction compared to the radial surface (61), and

[0126] The inner end (81) of the at least one diffuser side protrusion (8) is connected to the rear end (43) of the cover (4).

[0127] According to the configuration described in 7) above, the compressor housing has at least one diffuser-side protrusion protruding axially from the constriction surface towards the rear side (rear side) of the impeller. This diffuser-side protrusion suppresses backflow with a rotational component that points towards the impeller's rotational direction and occurs near the constriction surface. This suppresses the rotational pressure loss of the mainstream flow downstream of the impeller. By suppressing this backflow, rotational stall at the inlet of the diffuser path in the low-flow-rate operating region can be suppressed, thereby improving the efficiency of the centrifugal compressor.

[0128] In a centrifugal compressor, the impeller's downstream position creates a non-uniform velocity distribution. The aforementioned diffuser-side protrusion acts as a vortex simulator to suppress boundary layer stripping. Therefore, the efficiency of the centrifugal compressor can be improved not only when rotational stall occurs at the inlet of the diffuser path, but also at the compressor's normal operating point.

[0129] 8) The compressor housing (3) of at least one embodiment of this disclosure is a compressor housing for rotatably housing the impeller (2) of the centrifugal compressor (1), and includes:

[0130] The cover (4) includes a surface (41) that is opposite to the front end (24) of the impeller blade (23) of the impeller with a predetermined gap (G);

[0131] The diffuser surface (6) is located axially on the back side (26) of the impeller (2) compared to the rear end (43) of the cover surface (4), and includes a radial surface (61) extending along the radial direction and a tightening surface (63) connecting the inner end (62) of the radial surface (61) and the rear end (43) of the cover surface (4);

[0132] At least one diffuser-side protrusion (8) protrudes from the tightening surface (63) toward the back (26) side of the impeller (2) in the axial direction;

[0133] The at least one diffuser-side protrusion (8) is located on the hub surface (22A) side of the impeller (2) in the axial direction compared to the radial surface (61), and

[0134] The inner end (81) of the at least one diffuser side protrusion (8) is connected to the rear end (43) of the cover (4).

[0135] According to the configuration described in 8) above, the compressor housing has at least one diffuser-side protrusion protruding axially from the constriction surface towards the rear side (rear side) of the impeller. This diffuser-side protrusion suppresses backflow with a rotational component that points towards the impeller's rotational direction and occurs near the constriction surface. This suppresses the rotational pressure loss of the mainstream flow downstream of the impeller. By suppressing this backflow, rotational stall at the inlet of the diffuser path in the low-flow-rate operating region can be suppressed, thereby improving the efficiency of the centrifugal compressor.

[0136] In a centrifugal compressor, the impeller's downstream position creates a non-uniform velocity distribution. The aforementioned diffuser-side protrusion acts as a vortex simulator, thus suppressing boundary layer stripping. Therefore, the efficiency of the centrifugal compressor can be improved not only when rotary stall occurs at the inlet of the diffuser path, but also at the compressor's normal operating point.

[0137] 9) In some embodiments, based on the compressor housing (3) described in 7) or 8) above,

[0138] The at least one diffuser side protrusion (8) is integrally formed with the diffuser surface (6) by cutting or casting.

[0139] According to the configuration described in 9) above, the diffuser side protrusion is integrally formed with the diffuser surface by machining or casting. In this case, compared to fixing the diffuser side protrusion, which is manufactured separately from the diffuser surface, to the diffuser surface by welding or bolting, the surface roughness of the diffuser surface can be improved. By improving the surface roughness of the diffuser surface, the pressure loss of the main flow after passing through the impeller can be reduced.

[0140] 10) The centrifugal compressor (1) of at least one embodiment of the present disclosure includes the compressor housing (3) described in any one of 1) to 9) above.

[0141] Based on the above configuration (10), the pressure loss of the working fluid flowing inside the compressor housing can be effectively suppressed, thereby improving the efficiency of the centrifugal compressor.

[0142] Explanation of reference numerals in the attached figures

[0143] 1. Centrifugal compressor;

[0144] 2. Impeller;

[0145] 21 hubs;

[0146] 22 outside;

[0147] 22A hub surface;

[0148] 23 Impeller blades;

[0149] 24, 24A front end;

[0150] 25 leading edge;

[0151] 26. Back side;

[0152] 3. Compressor housing;

[0153] 31 air intakes;

[0154] 32 discharge outlets;

[0155] 33 covers;

[0156] 34. Inhalation inlet section;

[0157] 35 diffuser section;

[0158] 36 vortex sections;

[0159] 360° vortex flow path;

[0160] 361 flow path wall;

[0161] 4. Cover;

[0162] 41 sides;

[0163] 42 front end;

[0164] 43 rear end;

[0165] 5. Front inner circumferential surface;

[0166] 50 Inhalation Inlet Path;

[0167] 51 cone surface;

[0168] 52 front end;

[0169] 53 Axial plane;

[0170] 6. Diffuser surface;

[0171] 60 diffusion flow path;

[0172] 61 radial surfaces;

[0173] 62 Inner end;

[0174] 63 Shrinking surface;

[0175] 7 convex part;

[0176] 71 rear end;

[0177] 72 front end;

[0178] 73, 73A leading edge;

[0179] 74 Inner edge;

[0180] 75 First page;

[0181] 76. Second page;

[0182] 8. Diffusion side protrusion;

[0183] 81 Inner end;

[0184] 82 leading edge;

[0185] 83 rear lateral edge;

[0186] 84 outer end;

[0187] 85 First page;

[0188] 86 Second page;

[0189] 10 turbochargers;

[0190] 11 turbines;

[0191] 12 rotating axes;

[0192] 13 turbine rotors;

[0193] 14. Turbine casing;

[0194] 141 Turbine side inlet;

[0195] 142 turbine side exhaust outlet;

[0196] 15 bearings;

[0197] 16 bearing housing;

[0198] 161 sides;

[0199] CA axis;

[0200] G-gap;

[0201] MF is the mainstream;

[0202] RD rotation direction;

[0203] RF and RF2 reverse current;

[0204] X-axis;

[0205] XF (axial) front side;

[0206] XR (axial) rear side;

[0207] Y-radial.

Claims

1. A compressor housing for rotatably housing the impeller of a centrifugal compressor, characterized in that, have: A cover surface, which includes a surface that is opposite to the front end of the impeller blades of the impeller with a predetermined gap; The front inner circumferential surface is formed on the axial front side of the cover and is located radially outward compared to the front end of the cover. At least one protrusion that protrudes from the inner periphery of the front side toward the inner side of the radial direction; The rear end of the at least one protrusion is configured to connect with the front end of the cover surface. The at least one protrusion is configured as a plate and has an inclined leading edge that, in a cross-sectional view along the axis of the impeller, extends obliquely from the front end of the protrusion toward the rearward side relative to the axis of the impeller. The front inner circumferential surface includes a tapered surface that expands in diameter from the front end of the cover towards the front side and an axial surface that extends axially from the front end of the tapered surface towards the front side. The at least one protrusion extends throughout the entire axial length of at least the conical surface.

2. The compressor housing according to claim 1, In a cross-sectional view along the axis of the impeller, the length of the at least one protrusion relative to the axis varies in the radial direction.

3. The compressor housing according to claim 1, The at least one protrusion is configured such that the rear end of the protrusion is located upstream of the impeller in the direction of rotation compared to the front end of the protrusion.

4. The compressor housing according to claim 1, The at least one protrusion is integrally formed with the front side inner circumferential surface by cutting or casting.

5. The compressor housing according to claim 1, The front inner circumferential surface includes a tapered surface that expands in diameter from the front end of the cover towards the front side and an axial surface that extends axially from the front end of the tapered surface towards the front side. The at least one protrusion is provided only on the conical surface on the inner circumferential surface of the front side.

6. The compressor housing according to claim 1, further comprising: A diffuser surface, which is located axially on the back side of the impeller relative to the rear end of the shroud, and includes a radial surface extending along the radial direction and a contraction surface connecting the inner end of the radial surface to the rear end of the shroud. At least one diffuser-side protrusion protrudes from the tightening surface onto the rear side of the impeller in the axial direction; The at least one diffuser-side protrusion is located on the hub side of the impeller in the axial direction compared to the radial surface, and The inner end of at least one diffuser side protrusion is connected to the rear end of the cover.

7. A compressor housing for rotatably housing the impeller of a centrifugal compressor, characterized in that, have: A cover surface, which includes a surface that is opposite to the front end of the impeller blades of the impeller with a predetermined gap; A diffuser surface, which is located axially on the back side of the impeller relative to the rear end of the shroud, and includes a radially extending radial surface and a contracting surface connecting the inner end of the radial surface to the rear end of the shroud. At least one diffuser-side protrusion is formed as a plate having a first surface and a second surface located downstream of the impeller in the direction of rotation of the impeller compared to the first surface, protruding from the constriction surface onto the rear side of the impeller in the axial direction; The at least one diffuser-side protrusion is located on the hub side of the impeller in the axial direction compared to the radial surface, and The inner end of at least one diffuser side protrusion is connected to the rear end of the cover.

8. The compressor housing according to claim 6 or 7, The at least one diffuser side protrusion is integrally formed with the diffuser surface by cutting, machining, or casting.

9. A centrifugal compressor comprising a compressor housing according to any one of claims 1 to 8.

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