Impeller for a centrifugal compressor and centrifugal compressor

Abstract

A centrifugal compressor impeller having a hub (12) and at least one blade (15) provided on a hub face of the hub, wherein a hub-side end (16b) of a trailing edge (16) of the at least one blade is located radially outward of an outer peripheral portion (12e) of the hub and on either of a first line (L1) extending radially outward of the hub face of the hub or a second line (L2) extending radially outward of a back face of the hub.

Description

Technical Field

[0001] This disclosure relates to an impeller of a centrifugal compressor and a centrifugal compressor. Background Technology

[0002] Patent document 1 discloses a structure for improving the performance of a turbomachinery by suppressing two-dimensional flow in relation to a centrifugal compressor.

[0003] In this structure, the impeller has a hub plate and a plurality of blades arranged circumferentially spaced apart on one surface of the hub plate. The blades are formed by stacking multiple blade cross-sections in the blade spacing height direction of a reference impeller, where the blades, having a hub plate and blades orthogonal and composed of straight lines, are arranged as curved blades. During the stacking of the blade cross-sections in the blade spacing height direction, the tangential deflection and oscillation of the blade cross-section increase as at least one end face of the blade from the hub plate side end and the opposite end of the hub plate moves towards the middle of the spacing.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 5730649 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, in centrifugal compressors, reducing the impeller's outer diameter reduces its weight and inertia. For example, when using a centrifugal compressor in a turbocharger, reducing impeller inertia improves the turbocharger's response. However, in centrifugal compressors, there's a tendency for reducing the impeller's outer diameter to decrease the pressure ratio; therefore, suppressing this decrease in pressure ratio with a lightweight impeller is not easy.

[0009] Furthermore, in a centrifugal compressor, a portion of the compressed air, caused by the impeller's rotation, flows from the impeller outlet to the gap between the back of the impeller and the casing, creating a gap flow. If this gap flow increases, the efficiency of the centrifugal compressor decreases.

[0010] Patent document 1 does not disclose any insights for solving these problems in centrifugal compressors.

[0011] In view of the above, the purpose of this disclosure is to provide an impeller for a centrifugal compressor and a centrifugal compressor that can suppress the decrease in pressure ratio with low weight, thereby improving efficiency by suppressing interstitial flow.

[0012] Solution for solving the problem

[0013] To achieve the above objectives, the impeller of a centrifugal compressor according to at least one embodiment of the present disclosure includes a hub and at least one blade disposed on the hub surface, wherein,

[0014] The hub-side end of the trailing edge of at least one blade is located radially outward compared to the outer periphery of the hub.

[0015] And it lies on either a first line extending radially outward from the hub face of the hub, or a second line extending radially outward from the back face of the hub.

[0016] Invention Effects

[0017] According to this disclosure, an impeller for a centrifugal compressor and a centrifugal compressor are provided, which can suppress the decrease in pressure ratio with low weight, thereby improving efficiency by suppressing interstitial flow. Attached Figure Description

[0018] Figure 1 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 of a turbocharger 2 according to one embodiment.

[0019] Figure 2 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4A) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 shown.

[0020] Figure 3 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4B) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 shown.

[0021] Figure 4 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4C) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 shown.

[0022] Figure 5 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4D) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 shown.

[0023] Figure 6 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4E) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 shown.

[0024] Figure 7This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4F) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 shown.

[0025] Figure 8 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4G) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 shown.

[0026] Figure 9 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4H) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 shown.

[0027] Figure 10 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4I) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 shown.

[0028] Figure 11 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4J) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 shown.

[0029] Figure 12 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4K) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 shown.

[0030] Figure 13 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4L) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 shown.

[0031] Figure 14 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4M) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 shown.

[0032] Figure 15 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4N) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 shown.

[0033] Figure 16 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4O) according to one embodiment, showing... Figure 1An example of the detailed structure of the centrifugal compressor 4 shown.

[0034] Figure 17 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4P) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 shown.

[0035] Figure 18 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4Q) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 shown.

[0036] Figure 19 yes Figure 2 A partially enlarged view of the centrifugal compressor 4 (4A) shown. Detailed Implementation

[0037] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, and relative arrangements of the constituent components described as embodiments or shown in the drawings are not intended to limit the scope of the invention, but are merely illustrative examples.

[0038] For example, expressions indicating relative or absolute configurations such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric" or "coaxial" not only precisely indicate such configurations, but also indicate relative or displacement states with tolerances or degrees of achieving the same function by angle or distance.

[0039] For example, expressions indicating that things are "the same", "equal", and "homogeneous" are equal not only indicate a state of strict equality, but also indicate a state of difference where there is a tolerance or a degree of difference in the ability to achieve the same function.

[0040] For example, expressions representing shapes such as quadrilaterals or cylinders not only represent shapes in the strict geometric sense, but also, within the range that can achieve the same effect, shapes that include concave or convex parts or chamfered parts.

[0041] On the other hand, expressions such as “having,” “equipped with,” “possessing,” “including,” or “having” a constituent element are not exclusive expressions that exclude the existence of other constituent elements.

[0042] Figure 1 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 of a turbocharger 2 according to one embodiment.

[0043] like Figure 1As shown, the centrifugal compressor 4 includes an impeller 6, a housing 7 that houses the impeller 6, and a housing 10 that houses a bearing (not shown) that supports the impeller 6.

[0044] The impeller 6 includes a hub 12 and at least one blade 15 disposed on a hub surface 13 of the hub 12. In this embodiment, the impeller 6 includes a plurality of blades 15 disposed at intervals on the hub surface 13 in the circumferential direction of the impeller 6. Here, the hub surface 13 refers to the surface of the hub 12 opposite to the housing 7, which is a curved surface that is smoothly curved into a concave shape along the blades 15. Hereinafter, the circumferential direction of the impeller 6 will be referred to as "circumferential direction" only, the axial direction of the impeller 6 (the direction along the axis of rotation of the impeller 6) will be referred to as "axial direction" only, and the radial direction of the impeller 6 will be referred to as "radial direction" only.

[0045] The housing 7 includes a shroud 8 surrounding a plurality of blades 15 of the impeller 6 and a vortex portion 9 forming a vortex flow path 20 on the outer periphery of the impeller 6.

[0046] An airflow path 18 is formed between the impeller 6 and the shroud 8. Air (fluid) flowing into the airflow path 18 from the air inlet 5 of the centrifugal compressor 4 is compressed by the impeller 6 and flows through the diffuser path 19 on the downstream side of the airflow path 18 to the vortex path 20. The diffuser path 19 through which the air compressed by the impeller 6 flows is defined by the shroud side wall 50 of the housing 7 and the hub side wall 26 of the outer casing 10. A gap 22 is formed between the hub 12 of the impeller 6 and the outer casing 10.

[0047] like Figure 1 As shown, if the position closest to the shroud portion 8 on the trailing edge 16 of the blade 15 is designated as the shroud-side end 16a of the trailing edge 16, and the position closest to the hub 12 on the trailing edge 16 of the blade 15 is designated as the hub-side end 16b of the trailing edge 16, then the hub-side end 16b of the trailing edge 16 is located radially outward compared to the outer periphery 12e of the hub 12. In the illustrated configuration, the entire trailing edge 16 is located radially outward compared to the outer periphery 12e of the hub 12. Here, the outer periphery 12e of the hub 12 refers to the radially outward end of the hub 12, i.e., the portion connecting the hub surface 13 and the back surface 14 of the hub 12.

[0048] Figure 2 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4A) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 shown.

[0049] like Figure 2 As shown, if the line extending radially outward from the hub surface 13 of the hub 12 is designated as the first line L1 (first line), then the hub side end 16b of the rear edge 16 lies on the first line L1. Figure 2In the manner shown, the first line L1 is an imaginary straight line extending radially outward from the outer peripheral end 13a of the hub surface 13, along the tangential direction of the hub surface 13.

[0050] The blade 15 includes a blade root peripheral portion 24 that connects the hub-side end 16b of the trailing edge 16 to the outer periphery 12e of the hub 12. In the illustrated embodiment, the blade root peripheral portion 24 extends along a first line L1 such that it connects the hub-side end 16b of the trailing edge 16 and the outer periphery 13a of the hub surface 13. Furthermore, the trailing edge 16 is formed along the axial direction and extends parallel to the axial direction.

[0051] The housing 10 includes a hub sidewall 26 opposite to the outer periphery 24 of the blade root, a back sidewall 28 opposite to the back surface 14 of the impeller 6, and a stepped surface 30 extending along the axial direction to connect the hub sidewall 26 and the back sidewall 28. The stepped surface 30 is an opposing wall surface opposite to the outer periphery 12e of the hub 12. The outer periphery 24 of the blade root is formed along the hub sidewall 26 and extends parallel to the hub sidewall 26.

[0052] according to Figure 2 In the structure shown, the hub-side end 16b of the trailing edge 16 is located radially outward compared to the outer peripheral portion 12e (outer peripheral end of the hub 12). Therefore, compared to having... Figure 2 Compared to a structure with the same outer diameter of impeller 6 as shown, but with the radial position of the outer peripheral end 13a of the hub surface 13 extended to the radial position of the hub side end 16b of the trailing edge 16, it is possible to suppress the decrease in the pressure ratio of the centrifugal compressor 4 and reduce the weight of impeller 6. Furthermore, compared to a structure having the same outer diameter of impeller 6 as shown, but with the radial position of the outer peripheral end 13a of the hub surface 13 extended to the radial position of the hub side end 16b of the trailing edge 16, it is possible to suppress the decrease in the pressure ratio of the centrifugal compressor 4 and reduce the weight of impeller 6. Figure 2 Compared to a structure with the same outer diameter of hub 12, but with the radial position of the hub side end 16b of the trailing edge 16 reduced to the radial position of the outer peripheral end 13a of the hub surface 13, the pressure ratio of the centrifugal compressor 4 can be increased while suppressing the increase in impeller weight. This allows for the suppression of pressure ratio reduction in a lighter impeller. Furthermore, by reducing the outer diameter of hub 12, the diameter of gap 22 also decreases, thus suppressing gap flow and reducing gap losses.

[0053] Furthermore, the hub-side end 16b of the trailing edge 16 is located on the first line L1 that extends the hub surface 13 radially outward. Therefore, the blades 15 of the impeller 6 cover the gap 22 between the hub 12 and the housing 10. As the impeller 6 rotates, centrifugal force acts on the air near the inlet of the gap 22 (the gap between the outer periphery 12e of the hub 12 and the housing 10), which can further improve the effect of suppressing the flow of air into the gap 22.

[0054] Thus, based on the impeller 6 of the centrifugal compressor 4 (4A), the decrease in the pressure ratio of the centrifugal compressor 4 can be suppressed under low weight, and the efficiency of the centrifugal compressor 4 can be further improved by suppressing interstitial flow.

[0055] Figure 3 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4B) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 is shown. Figure 3 In the structure shown, unless otherwise specified, it is consistent with... Figure 2 The common reference numerals for the various structures shown are as follows: Figure 2 For structures that are identical as shown, explanations are omitted.

[0056] Figure 3 The structure shown is Figure 2 The difference in the structure shown is that the trailing edge 16 is inclined radially inward toward the hub 12 side. That is, in the impeller 6 of the centrifugal compressor 4 (4B), the trailing edge 16 extends in a straight line with an inclination relative to the axial direction, such that the shroud-side end 16a is located radially outward than the hub-side end 16b. The shroud portion 8 side of the trailing edge 16 protrudes radially outward compared to the hub 12 side of the trailing edge.

[0057] Figure 4 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4C) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 is shown. Figure 4 In the structure shown, unless otherwise specified, it is consistent with... Figure 2 The common reference numerals for the various structures shown are as follows: Figure 2 For structures that are identical as shown, explanations are omitted.

[0058] Figure 4 The structure shown is Figure 2 The difference in the structure shown is that the trailing edge 16 is inclined radially outward toward the hub 12 side. That is, in the impeller 6 of the centrifugal compressor 4 (4C), the trailing edge 16 extends in a straight line with an inclination relative to the axial direction, such that the shroud-side end 16a is located radially inward than the hub-side end 16b. The hub-side of the trailing edge 16 protrudes radially outward compared to the shroud-side of the trailing edge 16.

[0059] Figure 5 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4D) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 is shown. Figure 5 In the structure shown, unless otherwise specified, it is consistent with... Figure 2The common reference numerals for the various structures shown are as follows: Figure 2 For structures that are identical as shown, explanations are omitted.

[0060] Figure 5 The structure shown is Figure 2 The difference in the structure shown is that the trailing edge 16 is smoothly curved in a manner that moves radially outward from the shroud side end 16a toward the central portion 16c of the trailing edge 16, and radially inward from the central portion 16c toward the hub side end 16b of the trailing edge 16. That is, in the impeller 6 of the centrifugal compressor 4 (4D), the trailing edge 16 is smoothly curved such that the central portion 16c of the trailing edge 16 is located radially outward compared to both the shroud side end 16a and the hub side end 16b of the trailing edge 16.

[0061] exist Figures 3-5 In any of the centrifugal compressors 4 (4B-4D) shown, the hub-side end 16b of the trailing edge 16 is located radially outward compared to the outer periphery 12e (outer periphery end of the hub 12), and the hub-side end 16b of the trailing edge 16 lies on the first line L1 extending radially outward from the hub surface 13. Therefore, based on the... Figure 2 For the same reason shown, the reduction in the pressure ratio of the centrifugal compressor 4 can be suppressed with low weight, and the efficiency of the centrifugal compressor 4 can be improved by suppressing interstitial flow.

[0062] Furthermore, since the trailing edge 16 is located radially outward compared to the outer periphery 12e of the hub 12, an increase in total pressure is generated due to the expansion of the outer diameter of the impeller 6. Therefore, as Figures 3-5 As shown, by adjusting the shape of the portion of the blade 15 that protrudes more than the outer periphery 12e of the hub 12, the uneven total pressure distribution generated by the impeller 6 can be homogenized, suppressing stripping in the diffusion path 19. In particular, in Figure 3 The centrifugal compressor 4 (4B) shown and Figure 5 In the centrifugal compressor 4 (4D) shown, the reduction in the mass of the hub 12 results in a reduction in the centrifugal stress acting on the hub.

[0063] Figure 6 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4E) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 is shown. Figure 6 In the structure shown, unless otherwise specified, it is consistent with... Figure 3 The common reference numerals for the various structures shown are as follows: Figure 3 For structures that are identical as shown, explanations are omitted.

[0064] Figure 6 The structure shown is Figure 3The difference in the structure shown is that the outer periphery 12e of the hub 12 has a C-surface 32 formed in a manner that is radially outward compared to the hub surface 13 side and the rear surface 14 side. The C-surface 32 is formed as a plane and is inclined radially inward as it moves from the hub surface 13 side toward the rear surface 14 side. Furthermore, in Figure 6 In the structure shown, the stepped surface 30 of the housing 10 includes a C-surface 52 formed parallel to the C-surface 32. The C-surface 52 extends radially inward from the hub sidewall 26 toward the rear sidewall 28.

[0065] Figure 7 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4F) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 is shown. Figure 7 In the structure shown, unless otherwise specified, it is consistent with... Figure 3 The common reference numerals for the various structures shown are as follows: Figure 3 For structures that are identical as shown, explanations are omitted.

[0066] Figure 7 The structure shown is Figure 3 The difference in the structure shown is that the outer periphery 12e of the hub 12 has a concave R-surface 34 formed in a manner that is radially outward compared to the rear side 14. The R-surface 34 is smoothly curved and inclined radially inward as it moves from the hub side 13 toward the rear side 14. Additionally, in Figure 7 In the structure shown, the stepped surface 30 of the housing 10 includes a convex R-surface 54 formed parallel to the R-surface 34. The R-surface 54 is configured to be smoothly curved, extending radially inward from the hub sidewall 26 toward the rear sidewall 28.

[0067] exist Figure 6 The centrifugal compressor 4 (4E) shown and Figure 7 In any of the centrifugal compressors 4 (4F) shown, the hub-side end 16b of the trailing edge 16 is located radially outward compared to the outer periphery 12e (outer peripheral end of the hub 12), and the hub-side end 16b of the trailing edge 16 lies on the first line L1 extending radially outward from the hub surface 13. Therefore, based on the... Figure 2 For the same reason shown, the reduction in the pressure ratio of the centrifugal compressor 4 can be suppressed with low weight, and the efficiency of the centrifugal compressor 4 can be improved by suppressing interstitial flow.

[0068] In addition, Figure 6 The centrifugal compressor 4 (4E) shown and Figure 7In any of the centrifugal compressors 4 (4F) shown, the gap 22 between the outer periphery 12e of the hub 12 and the stepped surface 30 can be tilted in the opposite direction to the flow direction. As a result, the main flow in the airflow path 18 can be suppressed from entering the gap 22, the gap loss can be reduced, and thus the efficiency of the centrifugal compressor 4 can be improved.

[0069] Figure 8 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4G) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 is shown. Figure 8 In the structure shown, unless otherwise specified, it is consistent with... Figure 3 The common reference numerals for the various structures shown are as follows: Figure 3 For structures that are identical as shown, explanations are omitted.

[0070] Figure 8 The structure shown is Figure 3 The difference in the structure shown is that the hub side end 16b connecting the trailing edge 16 and the outer periphery 24 of the blade root of the outer periphery 12e of the hub 12 has a C-face edge 36. Figure 8 In the structure shown, the outer periphery 24 of the blade root includes a portion 35 extending radially inward from the hub-side end 16b of the trailing edge 16, and a C-face edge 36 connecting the radially inward end of the portion 35 and the outer periphery 12e. The C-face edge 36 is inclined radially inward as it moves away from the portion 35 along the axial direction, and connects to the boundary of the outer periphery 12e and the back surface 14.

[0071] In addition, Figure 8 In the structure shown, the stepped surface 30 of the housing 10 includes a C-surface 52 formed parallel to the C-surface edge 36, the C-surface 52 extending radially inward from the hub sidewall 26 toward the rear sidewall 28.

[0072] Figure 9 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4H) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 is shown. Figure 9 In the structure shown, unless otherwise specified, it is consistent with... Figure 3 The common reference numerals for the various structures shown are as follows: Figure 3 For structures that are identical as shown, explanations are omitted.

[0073] Figure 9 The structure shown is Figure 3 The difference in the structure shown is that the outer periphery 24 of the blade root of the connecting hub side end 16b of the trailing edge 16 and the outer periphery 12e of the hub 12 has a concave R-shaped edge 38. Figure 9In the structure shown, the outer periphery 24 of the blade root includes a portion 35 extending radially inward from the hub-side end 16b of the trailing edge 16, and a concave R-shaped edge 38 connecting the radially inward end of the portion 35 and the outer periphery 12e. The R-shaped edge 38 is smoothly curved radially inward as it moves away from the portion 35 along the axial direction, and connects to the boundary of the outer periphery 12e and the back surface 14.

[0074] In addition, Figure 9 In the structure shown, the stepped surface 30 of the housing 10 includes a convex R-surface 54 formed parallel to the R-surface edge 38. The R-surface 54 is configured to be smoothly curved, extending radially inward from the hub sidewall 26 toward the rear sidewall 28.

[0075] exist Figure 8 The centrifugal compressor 4 (4G) shown is as follows Figure 9 In any of the centrifugal compressors 4 (4H) shown, the hub-side end 16b of the trailing edge 16 is located radially outward than the outer periphery 12e (outer periphery end of the hub 12), and the hub-side end 16b of the trailing edge 16 is located on the first line L1 extending radially outward from the hub surface 13. Therefore, based on the... Figure 2 For the same reason shown, the reduction in the pressure ratio of the centrifugal compressor 4 can be suppressed with low weight, and the efficiency of the centrifugal compressor 4 can be improved by suppressing interstitial flow.

[0076] In addition, Figure 8 The centrifugal compressor 4 (4G) shown is as follows Figure 9 In any of the centrifugal compressors 4 (4H) shown, the gap 22 between the C-edge 36 or R-edge 38 of the outer periphery 24 of the blade root and the stepped surface 30 can be tilted in the opposite direction to the flow direction. As a result, the main flow in the airflow path 18 can be suppressed from entering the gap 22, the gap loss can be reduced, and thus the efficiency of the centrifugal compressor 4 can be improved. In addition, since no corner is generated at the outer periphery 24 of the blade root, stress concentration can be mitigated, thus the strength of the blade 15 relative to centrifugal stress can be improved.

[0077] Figure 10 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4I) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 is shown. Figure 10 In the structure shown, unless otherwise specified, it is consistent with... Figure 3 The common reference numerals for the various structures shown are as follows: Figure 3 For structures that are identical as shown, explanations are omitted.

[0078] Figure 10 The structure shown is Figure 3The difference in the structure shown is that the outer periphery 12e of the hub 12 has a C-surface 40 formed in a manner that is radially outward compared to the hub surface 13 side, on the back surface 14 side. The C-surface 40 is formed as a plane, inclined radially outward as it moves from the hub surface 13 side toward the back surface 14 side. Furthermore, in Figure 10 In the structure shown, the stepped surface 30 of the outer casing 10 is formed parallel to the C-surface 40. That is, the stepped surface 30 is also configured as a C-surface, extending radially outward from the hub sidewall 26 toward the rear sidewall 28. It should be noted that in the centrifugal compressor 4 (4I), the outer peripheral portion 12e may also have a concave R-surface that replaces the C-surface 40 or, together with the C-surface 40, slopes radially outward from the hub side 13 toward the rear side 14.

[0079] exist Figure 10 In the impeller 6 of the centrifugal compressor 4 (4I) shown, the hub-side end 16b of the trailing edge 16 is located radially outward than the outer periphery 12e of the hub 12, and the hub-side end 16b of the trailing edge 16 is located on the first line L1 extending radially outward from the hub surface 13. Therefore, based on the... Figure 2 For the same reason shown, the reduction in the pressure ratio of the centrifugal compressor 4 can be suppressed with low weight, and the efficiency of the centrifugal compressor 4 can be improved by suppressing interstitial flow.

[0080] Furthermore, depending on the internal flow conditions of the centrifugal compressor 4, peeling f may occur on the hub sidewall 26. In such cases, by employing methods such as... Figure 10 The inclined C-surface 40 and stepped surface 30 shown make the shape of the gap 22 inclined, which can reduce gap loss in the event of peeling f as described above.

[0081] Figure 11 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4J) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 is shown. Figure 11 In the structure shown, unless otherwise specified, it is consistent with... Figure 10 The common reference numerals for the various structures shown are as follows: Figure 10 For structures that are identical as shown, explanations are omitted.

[0082] Figure 11 The structure shown is Figure 10 The difference in the structure shown is that the hub side end 16b connecting the trailing edge 16 and the outer peripheral portion 24 of the blade root of the outer peripheral portion 12e of the hub 12 has a concave R-face edge 38. The R-face edge 38 is smoothly curved toward the radially inward as it moves away from the trailing edge 16 along the axial direction, and connects with the boundary of the outer peripheral portion 12e and the back surface 14.

[0083] In addition, Figure 11 In the structure shown, the stepped surface 30 of the housing 10 includes a convex R-surface 54 formed parallel to the R-surface edge 38. The R-surface 54 is configured to be smoothly curved, extending radially inward from the hub sidewall 26 side toward the rear sidewall 28 side.

[0084] exist Figure 11 In the impeller 6 of the centrifugal compressor 4 (4J) shown, the hub-side end 16b of the trailing edge 16 is located radially outward than the outer periphery 12e of the hub 12, and the hub-side end 16b of the trailing edge 16 is located on the first line L1 extending radially outward from the hub surface 13. Therefore, based on the... Figure 2 For the same reason shown, the reduction in the pressure ratio of the centrifugal compressor 4 can be suppressed with low weight, and the efficiency of the centrifugal compressor 4 can be improved by suppressing interstitial flow.

[0085] In addition, since the outer periphery 24 of the blade root has a concave R-shaped edge 38, no corner is generated in the outer periphery 24 of the blade root, thus alleviating stress concentration and improving the strength of the blade 15 relative to centrifugal stress.

[0086] In addition, since a portion of the blade 15 is disposed inside the gap 22, the centrifugal force accompanying the rotation of the blade 15 generates a force that causes fluid to be discharged from the gap 22 toward the outer peripheral side (i.e., the air flow path 18 side), which helps to reduce gap loss and axial force load.

[0087] It should be noted that in the centrifugal compressor 4 (4J), the outer peripheral portion 12e may also have a concave R-surface that, instead of the C-surface 40, or together with the C-surface 40, slopes radially outward from the hub surface 13 side toward the rear surface 14 side. Alternatively, instead of the case where the stepped surface 30 is formed by bending the R-surface into a convex shape, the stepped surface 30 may be formed by the C-surface.

[0088] Figure 12 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4K) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 is shown. Figure 12 In the structure shown, unless otherwise specified, it is consistent with... Figure 2 The common reference numerals for the various structures shown are as follows: Figure 2 For structures that are identical as shown, explanations are omitted.

[0089] like Figure 12 As shown, if the line extending radially outward from the hub surface 13 of the hub 12 is designated as the first line L1, then the hub side end 16b of the rear edge 16 lies on the first line L1. Figure 12In the manner shown, the first line L1 is a curved line that extends radially outward from the outer peripheral end 13a of the hub surface 13 and is continuous with the hub surface 13.

[0090] The blade 15 includes a blade root peripheral portion 24 that connects the hub-side end 16b of the trailing edge 16 to the outer periphery 12e of the hub 12. In the illustrated embodiment, the blade root peripheral portion 24 extends in a curved shape along the first line L1, connecting the hub-side end 16b of the trailing edge 16 and the outer periphery 13a of the hub surface 13. Furthermore, the trailing edge 16 extends in a straight line at an angle relative to the axial direction, with the shroud-side end 16a located radially outward compared to the hub-side end 16b.

[0091] The outer periphery 24 of the blade root is formed along the hub sidewall 26 and extends parallel to the hub sidewall 26. The hub sidewall 26 includes a curved portion 27 that bends along the outer periphery 24 of the blade root. The outer periphery 24 of the blade root is formed along the curved portion 27 and is formed parallel to the curved portion 27.

[0092] exist Figure 12 In the impeller 6 of the centrifugal compressor 4 (4K) shown, the hub-side end 16b of the trailing edge 16 is located radially outward than the outer periphery 12e of the hub 12, and the hub-side end 16b of the trailing edge 16 is located on the first line L1 extending radially outward from the hub surface 13. Therefore, based on the... Figure 2 For the same reason shown, the reduction in the pressure ratio of the centrifugal compressor 4 can be suppressed with low weight, and the efficiency of the centrifugal compressor 4 can be improved by suppressing interstitial flow.

[0093] Figure 13 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4L) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 is shown. Figure 13 In the structure shown, unless otherwise specified, it is consistent with... Figure 2 The common reference numerals for the various structures shown are as follows: Figure 2 For structures that are identical as shown, explanations are omitted.

[0094] exist Figure 13 In the structure shown, if the line extending radially outward from the back surface 14 of the hub 12 is designated as the second line L2, then the hub side end 16b of the trailing edge 16 lies on the second line L2. Figure 13 In the manner shown, the second line L2 is an imaginary line extending radially outward from the outer peripheral end 13a of the back surface 14, in a straight line along the tangential direction (radial) of the back surface 14.

[0095] The blade 15 includes a blade root peripheral portion 24 that connects the hub-side end 16b of the trailing edge 16 to the outer periphery 12e of the hub 12. In the illustrated embodiment, the blade root peripheral portion 24 extends along a second line L2 in a manner that connects the hub-side end 16b of the trailing edge 16 to the outer periphery 14a of the back surface 14.

[0096] exist Figure 13 In the structure shown, the outer shell 10 does not have Figure 2 The stepped surface 30 shown includes a hub sidewall surface 26 opposite to the outer periphery 24 of the blade root and a back sidewall surface 28 opposite to the back surface 14 of the impeller 6 and connected to the hub sidewall surface 26. The outer periphery 24 of the blade root is formed along the hub sidewall surface 26 and extends parallel to the hub sidewall surface 26.

[0097] according to Figure 13 In the structure shown, the hub-side end 16b of the trailing edge 16 is located radially outward compared to the outer periphery 12e of the hub 12. Therefore, compared to having... Figure 13 Compared to a structure with the same outer diameter of impeller 6 as shown, and where the radial position of the hub side end 16b of the trailing edge 16 coincides with the radial position of the outer peripheral end 13a of the hub surface 13, it is possible to suppress the decrease in the pressure ratio of the centrifugal compressor 4 and reduce the weight of impeller 6. Furthermore, compared to a structure having the same... Figure 13 Compared to a structure where the outer diameter of the impeller 6 is the same as the outer diameter of the hub 12, and the radial position of the hub side end 16b of the trailing edge 16 coincides with the radial position of the outer peripheral end 13a of the hub surface 13, the pressure ratio of the centrifugal compressor 4 can be increased while suppressing the increase in impeller weight. This allows for the suppression of pressure ratio reduction in a lightweight impeller. Furthermore, by reducing the outer diameter of the hub 12, the diameter of the gap 22 also decreases, thus suppressing gap flow and reducing gap losses.

[0098] Furthermore, the hub-side end 16b of the trailing edge 16 is located on the second line L2 that extends radially outward from the back surface 14. Therefore, as the impeller 6 rotates, centrifugal force acts on the air near the inlet of the gap 22 (the gap between the outer periphery 12e of the hub 12 and the housing 10), which further enhances the effect of suppressing the flow of air into the gap 22. In addition, since the gap 22 between the hub 12 and the housing 10 extends from the position of the outer periphery 12e of the hub 12 in the opposite direction to the mainstream airflow from the airflow path 18, the mainstream airflow from the airflow path 18 can be suppressed from entering the gap 22, which can further reduce gap loss.

[0099] In this way, the impeller 6 of the centrifugal compressor 4 (4L) can suppress the decrease in the pressure ratio of the centrifugal compressor 4 under low weight, and can improve the efficiency of the centrifugal compressor 4 by suppressing interstitial flow.

[0100] Figure 14This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4M) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 is shown. Figure 14 In the structure shown, unless otherwise specified, it is consistent with... Figure 13 The common reference numerals for the various structures shown are as follows: Figure 13 For structures that are identical as shown, explanations are omitted.

[0101] Figure 14 The structure shown is Figure 13 The difference in the structure shown is that the hub 12 has a convex R-shaped surface 42 that is smoothly curved in a way that connects the hub surface 13 and the outer peripheral portion 12e.

[0102] exist Figure 14 In the impeller 6 of the centrifugal compressor 4 (4M) shown, the hub-side end 16b of the trailing edge 16 is located radially outward compared to the outer periphery 12e (outer periphery end of the hub 12), and the hub-side end 16b of the trailing edge 16 is located on the second line L2 extending radially outward from the back surface 14. Therefore, based on the... Figure 13 For the same reason shown, the reduction in the pressure ratio of the centrifugal compressor 4 can be suppressed with low weight, and the efficiency of the centrifugal compressor 4 can be improved by suppressing interstitial flow.

[0103] In addition, since the hub 12 has a convex R-shaped surface 42 connecting the hub surface 13 and the outer peripheral portion 12e, the flow path area at the position of the outer peripheral portion 12e of the hub 12 can be suppressed from expanding sharply, thereby improving efficiency and performance.

[0104] Figure 15 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4N) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 is shown. Figure 15 In the structure shown, unless otherwise specified, it is consistent with... Figure 13 The common reference numerals for the various structures shown are as follows: Figure 13 For structures that are identical as shown, explanations are omitted.

[0105] Figure 15 The structure shown is Figure 13 The difference in the structure shown is that the hub 12 has an inner surface 44 that is continuous with the hub surface 13 and inscribed relative to the second line L2. Figure 15 In the structure shown, the inner part 44 is internally connected to the outer periphery 24 of the leaf root.

[0106] exist Figure 15Similarly, in the impeller 6 of the centrifugal compressor 4 (4N) shown, the hub-side end 16b of the trailing edge 16 is located radially outward compared to the outer periphery 12e (outer periphery end of the hub 12), and the hub-side end 16b of the trailing edge 16 is located on the second line L2 extending radially outward from the back surface 14. Therefore, based on the... Figure 13 For the same reason shown, the reduction in the pressure ratio of the centrifugal compressor 4 can be suppressed with low weight, and the efficiency of the centrifugal compressor 4 can be improved by suppressing interstitial flow.

[0107] In addition, since the hub 12 has an inner surface 44 that is continuous with the hub surface 13 and is inscribed relative to the second line L2, the flow path area at the outer periphery 12e of the hub 12 can be suppressed from expanding sharply, thereby improving efficiency and performance.

[0108] Furthermore, by reducing the angle between the mainstream flow in the airflow path 18 and the hub sidewall 26 of the housing 10, the entry of the mainstream into the gap 22 can be suppressed, thereby reducing gap loss. It should be noted that... Figure 15 In the structure shown, the outer periphery 12e of the hub 12 may also include a small R-surface.

[0109] Figure 16 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4O) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 is shown. Figure 16 In the structure shown, unless otherwise specified, it is consistent with... Figure 13 The common reference numerals for the various structures shown are as follows: Figure 13 For structures that are identical as shown, explanations are omitted.

[0110] Figure 16 The structure shown is Figure 13 The difference in the structure shown is that the back surface 14 of the impeller 6 has a concave curved surface 46. The curved surface 46 is smoothly curved and inclined radially inwards as it moves away from the outer periphery 12e of the impeller 6 along the axial direction. Additionally, in Figure 16 In the structure shown, the back sidewall 28 of the outer casing 10 is formed parallel to the curved surface 46. That is, the back sidewall 28 is configured to be smoothly curved as a convex surface, extending radially inward as it moves away from the hub sidewall 26 along the axial direction.

[0111] According to this structure, besides Figure 13 In addition to the effects of the structure shown, the back surface 14 of the impeller 6 has a curved surface 46, which can improve the strength of the hub 12 relative to centrifugal stress.

[0112] Figure 17This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4P) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 is shown. Figure 17 In the structure shown, unless otherwise specified, it is consistent with... Figure 16 The common reference numerals for the various structures shown are as follows: Figure 16 For structures that are identical as shown, explanations are omitted.

[0113] exist Figure 17 In the structure shown, with Figure 13 The difference in the structure shown is that the outer periphery 24 of the blade root has a curved edge 48 that is continuous with the curved surface 46. Furthermore, the second line L2 is an imaginary, curved line that extends radially outward from the outer periphery 14a of the back surface 14 and is continuous with the back surface 14; the hub-side end 16b of the trailing edge 16 lies on the second line L2. Additionally, the portion of the hub sidewall 26 opposite the curved edge 48 is configured to be smoothly curved as a convex surface in a manner parallel to the curved edge 48.

[0114] According to this structure, besides Figure 13 In addition to the effects of the structure shown, the back surface 14 of the impeller 6 has a curved surface 46, which can improve the strength of the hub 12 relative to centrifugal stress.

[0115] Figure 18 This is a schematic cross-sectional view along the axial direction of a centrifugal compressor 4 (4Q) according to one embodiment, showing... Figure 1 An example of the detailed structure of the centrifugal compressor 4 is shown. Figure 18 In the structure shown, unless otherwise specified, it is consistent with... Figure 16 The common reference numerals for the various structures shown are as follows: Figure 16 For structures that are identical as shown, explanations are omitted.

[0116] exist Figure 18 In the structure shown, the second line L2 is an imaginary, curved line that extends radially outward from the outer peripheral end 14a of the back surface 14 and is continuous with the back surface 14, and coincides with the first line L1 that extends radially outward from the hub surface 13. Therefore, the hub side end 16b of the trailing edge 16 is located on the second line L2 and on the first line L1.

[0117] According to this structure, besides Figure 16 In addition to the effects of the structure shown, it can suppress the rapid expansion of the flow path area at the outer periphery 12e of the hub 12, thereby improving efficiency and effectiveness.

[0118] In several implementations, for example, Figure 19As shown, when the width of the diffusion path 19 at the hub side end 16b of the trailing edge 16 is set to W1, and the distance along the axial direction between the hub side end 16b of the trailing edge 16 and the hub side wall 26 is set to W2, the centrifugal compressor 4 is configured to satisfy 0.20≥W2 / W1. Preferably, the centrifugal compressor 4 can satisfy 0.16≥W2 / W1.

[0119] As a result, with the rotation of the impeller 6, the centrifugal force is effectively applied to the air near the inlet of the gap 22 (the gap between the outer periphery 12e of the hub 12 and the outer casing 10), which can further improve the effect of suppressing the flow of air into the gap 22.

[0120] exist Figure 19 The structure shown is illustrated using the centrifugal compressor 4 (4A) described above as an example. However, in each of the centrifugal compressors 4 (4B to 4Q) described above, 0.20 ≥ W2 / W1 (more preferably 0.16 ≥ W2 / W1) can also be satisfied.

[0121] This disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0122] The contents described in the above embodiments can be understood, for example, as follows.

[0123] (1) The impeller (e.g., the impeller 6 described above) of at least one embodiment of the centrifugal compressor (e.g., the centrifugal compressor 4 (4A-4Q) described above) of the present disclosure includes a hub (e.g., the hub 12 described above) and at least one blade (e.g., the blade 15 described above) disposed on the hub surface (e.g., the hub surface 13 described above), wherein,

[0124] The hub-side end (e.g., hub-side end 16b) of the trailing edge (e.g., the trailing edge 16 described above) of at least one blade.

[0125] It is located radially outward compared to the outer periphery of the hub (e.g., the outer periphery 12e described above), and is located on either a first line extending radially outward from the hub face of the hub (e.g., the first line L1 described above) or a second line extending radially outward from the back face of the hub (e.g., the back face 14 described above) (e.g., the second line L2 described above).

[0126] According to the centrifugal compressor impeller described in (1) above, the hub-side end of the trailing edge is located radially outward compared to the outer periphery of the hub. Therefore, compared to a structure that maintains the outer diameter of the impeller and expands the radial position of the outer periphery of the hub surface to the radial position of the hub-side end of the trailing edge, it is possible to suppress the decrease in the pressure ratio of the centrifugal compressor and reduce the weight of the impeller. In addition, compared to a structure that reduces the outer diameter of the impeller and reduces the radial position of the hub-side end of the trailing edge to the radial position of the outer periphery of the hub surface, it is possible to increase the pressure ratio of the centrifugal compressor and suppress the increase in the weight of the impeller. In this way, it is possible to suppress the decrease in the pressure ratio in a low-weight impeller. Furthermore, by reducing the outer diameter of the hub, the diameter of the gap formed on the back side of the hub also becomes smaller, thus suppressing leakage flow (gap flow) into the gap and reducing losses caused by gap flow (gap loss).

[0127] Furthermore, the hub side of the trailing edge lies on either a first line extending radially outward from the hub face, or a second line extending radially outward from the back of the hub. Therefore, as the impeller rotates, centrifugal force acts on the air near the inlet of the aforementioned gap, further enhancing the effect of suppressing the inflow of gap flow.

[0128] Thus, according to the impeller of the centrifugal compressor described in (1) above, the reduction of the pressure ratio of the centrifugal compressor can be suppressed under low weight, thereby improving the efficiency of the centrifugal compressor by suppressing interstitial flow.

[0129] (2) In several embodiments, the impeller of the centrifugal compressor described in (1) above,

[0130] The hub side end of the rear edge is located on the first line.

[0131] According to the impeller of the centrifugal compressor described in (2) above, the reduction of the pressure ratio of the centrifugal compressor can be suppressed under low weight, thereby improving the efficiency of the centrifugal compressor by suppressing interstitial flow.

[0132] (3) In several embodiments, the impeller of the centrifugal compressor described in (2) above,

[0133] The rear edge guard side end (e.g., the guard side end 16a mentioned above) is located radially outward compared to the hub side end.

[0134] In a typical centrifugal compressor, the total pressure on the shroud side is more easily reduced compared to the total pressure on the hub side. Therefore, according to the structure described in (3) above, the uneven total pressure distribution generated by the impeller can be homogenized, suppressing the occurrence of stripping in the diffusion path. In addition, the reduction in mass of the portion near the outer periphery of the hub in the blades results in a reduction in the centrifugal stress acting on the hub.

[0135] (4) In several embodiments, the impeller of the centrifugal compressor described in (2) above,

[0136] The rear edge of the guard side is located radially inward than the hub side.

[0137] Depending on the internal flow state of the centrifugal compressor, there is a situation where the total pressure on the hub side is lower than the total pressure on the shroud side. Therefore, according to the structure described in (4) above, the uneven total pressure distribution generated by the impeller can be homogenized, and the occurrence of stripping in the diffusion path can be suppressed.

[0138] (5) In several embodiments, the impeller of the centrifugal compressor described in (2) above,

[0139] The central portion of the trailing edge (e.g., the central portion 16c described above) is located radially outward compared to the guard side end and the hub side end of the trailing edge.

[0140] Depending on the internal flow state of the centrifugal compressor, there is a situation where the total pressure in the central part of the trailing edge is lower than the total pressure on the hub side and the shroud side. Therefore, according to the structure described in (5) above, the uneven total pressure distribution generated by the impeller can be homogenized, and the occurrence of stripping in the diffusion path can be suppressed.

[0141] (6) In several embodiments, the impeller of the centrifugal compressor described in (2) above,

[0142] The outer periphery of the hub has a C-surface (e.g., C-surface 32 as described above) or a concave R-surface (e.g., R-surface 34 as described above) formed in such a way that the hub face side is located radially outward compared to the rear face side.

[0143] According to the centrifugal compressor impeller described in (6) above, the gap formed along the outer periphery of the hub can be tilted in the opposite direction to the mainstream flow direction of the centrifugal compressor. As a result, the mainstream flow into the gap can be suppressed, gap loss can be reduced, and thus the efficiency of the centrifugal compressor can be improved.

[0144] (7) In several embodiments, the impeller of the centrifugal compressor described in (2) above,

[0145] The at least one blade includes a blade root peripheral portion, which is the outer peripheral portion of the blade root connecting the hub side end of the trailing edge and the outer peripheral portion of the hub (e.g., the blade root peripheral portion 24 described above), having a C-face edge (e.g., the C-face edge 36 described above) or a concave R-face edge (e.g., the R-face edge 38 described above).

[0146] According to the centrifugal compressor impeller described in (7) above, the gap formed along the C-side or R-side edge of the outer periphery of the blade root can be tilted in the opposite direction to the mainstream flow direction of the centrifugal compressor. As a result, the mainstream flow into the gap can be suppressed, gap loss can be reduced, and thus the efficiency of the centrifugal compressor can be improved. In addition, since no corner is generated at the outer periphery of the blade root, stress concentration can be mitigated, thus the strength of the blade relative to centrifugal stress can be improved.

[0147] (8) In several embodiments, the impeller of the centrifugal compressor described in (2) above,

[0148] The outer periphery of the hub has a C-surface (e.g., the C-surface 40 described above) or a concave R-surface formed in such a way that the rear side is located radially outward compared to the hub face side.

[0149] Depending on the internal flow of the centrifugal compressor, there may be a situation where peeling f occurs on the hub side of the diffusion flow path. In such cases, by using the C-surface or concave R-surface described above (8) to tilt the shape of the gap along the outer circumferential surface of the hub, the gap loss in the case of peeling as described above can be reduced.

[0150] (9) In several embodiments, the impeller of the centrifugal compressor described in (8) above,

[0151] The at least one blade includes a blade root peripheral portion, which is the outer peripheral portion of the blade root connecting the hub side end of the trailing edge and the outer peripheral portion of the hub (e.g., the blade root peripheral portion 24 described above), having a C-face edge (e.g., the C-face edge 36 described above) or a concave R-face edge (e.g., the R-face edge 38 described above).

[0152] According to the centrifugal compressor impeller described in (9) above, since the outer periphery of the blade root has a C-shaped edge or a concave R-shaped edge, no corner is generated at the outer periphery 24 of the blade root, thus alleviating stress concentration and improving the strength of the blade relative to centrifugal stress.

[0153] In addition, since a portion of the blade is positioned inside the gap along the hub's dividing section, the centrifugal force accompanying the blade's rotation generates a flow that exits from the gap toward the outer periphery, which helps to reduce gap loss and axial force load.

[0154] (10) In several embodiments, the impeller of the centrifugal compressor described in (1) above,

[0155] The hub side end of the rear edge is located on the second line.

[0156] According to the impeller of the centrifugal compressor described in (10) above, the reduction of the pressure ratio of the centrifugal compressor can be suppressed under low weight, and the efficiency of the centrifugal compressor can be improved by suppressing interstitial flow.

[0157] (11) In several embodiments, the impeller of the centrifugal compressor described in (10) above,

[0158] The hub has a convex R-shaped portion (e.g., R-face 42 as described above) connecting the hub surface and the outer periphery.

[0159] According to the centrifugal compressor impeller described in (11) above, since the hub has a convex R-shaped surface connecting the hub surface and the outer periphery, it can suppress the rapid expansion of the flow path area at the outer periphery of the hub, thereby improving efficiency and performance.

[0160] (12) In several embodiments, the impeller of the centrifugal compressor described in (10) above,

[0161] The hub has an inner portion (e.g., the inner portion 44 described above) that is continuous with the hub surface and inscribed relative to the second line.

[0162] According to the centrifugal compressor impeller described in (12) above, since the hub has an inner surface that is continuous with the hub surface and is inscribed relative to the second line, it is possible to suppress the rapid expansion of the flow path area at the outer periphery of the hub, thereby improving efficiency and performance.

[0163] In addition, it can reduce the angle between the mainstream of the centrifugal compressor and the hub sidewall of the diffusion path, thereby suppressing the gap of the mainstream entering the back side of the impeller and reducing gap loss.

[0164] (13) In several embodiments, the impeller of the centrifugal compressor described in (10) above,

[0165] The back side of the hub has a concave curved surface (e.g., the curved surface 46 described above).

[0166] According to the centrifugal compressor impeller described in (13) above, since the back of the impeller has a curved surface, the strength of the hub relative to centrifugal stress can be improved.

[0167] (14) In several embodiments, the impeller of the centrifugal compressor described in (13) above,

[0168] The at least one blade includes a blade root peripheral portion, which is the outer peripheral portion of the blade root connecting the hub side end of the trailing edge and the outer peripheral portion of the hub (e.g., the blade root peripheral portion 24 described above), and has a curved edge (e.g., the curved edge 48 described above) that is continuous with the curved surface.

[0169] According to the centrifugal compressor impeller described in (14) above, since the back of the impeller has a curved surface, the strength of the hub relative to centrifugal stress can be improved.

[0170] (15) In several embodiments, the impeller of the centrifugal compressor described in (14) above,

[0171] The hub has an inner portion (e.g., the inner portion 44 described above) that is continuous with the hub surface and inscribed relative to the second line.

[0172] According to the centrifugal compressor impeller described above (15), since the hub has an inner surface that is continuous with the hub surface and is inscribed relative to the second line, it is possible to suppress the rapid expansion of the flow path area at the outer periphery of the hub, thereby improving efficiency and performance.

[0173] (16) The centrifugal compressor of at least one embodiment of the present disclosure comprises:

[0174] The impeller of any of the centrifugal compressors described in (1) to (15) above;

[0175] The sidewalls of the protective cover and the sidewalls of the hub define diffusion paths (e.g., diffusion path 19 described above) through which the fluid compressed by the impeller of the centrifugal compressor flows; wherein,

[0176] The width of the diffusion flow path at the hub side end of the trailing edge is set to W1.

[0177] When the distance along the axial direction between the hub side end of the rear edge and the hub side wall is set as W2, 0.20≥W2 / W1 is satisfied.

[0178] According to the centrifugal compressor described above (16), as the impeller rotates, the centrifugal force is effectively applied to the air near the inlet of the gap formed along the back of the impeller, which can further improve the effect of suppressing the flow from the gap to the gap.

[0179] (17) The centrifugal compressor of at least one embodiment of the present disclosure comprises:

[0180] The impeller of the centrifugal compressor described in (6) above;

[0181] The sidewalls of the shield and the sidewalls of the hub define diffusion paths (e.g., diffusion path 19 described above) through which the fluid compressed by the impeller of the centrifugal compressor flows.

[0182] The rear sidewall faces the rear side of the hub; wherein,

[0183] It also has opposing walls that connect the hub sidewall and the rear sidewall and are opposite to the outer peripheral surface of the hub. The opposing walls have a C-surface or a convex R-surface.

[0184] According to the centrifugal compressor described in (17) above, the gap between the outer periphery of the hub and the opposing wall can be tilted in the opposite direction to the flow direction. As a result, the mainstream inlet gap of the centrifugal compressor can be suppressed, the gap loss can be reduced, and thus the efficiency of the centrifugal compressor can be improved.

[0185] (18) The centrifugal compressor of at least one embodiment of the present disclosure comprises:

[0186] The impeller of the centrifugal compressor described in (7) above;

[0187] The sidewalls of the shield and the sidewalls of the hub define diffusion paths (e.g., diffusion path 19 described above) through which the fluid compressed by the impeller of the centrifugal compressor flows.

[0188] The rear sidewall faces the rear side of the hub; wherein,

[0189] It also has opposing walls that connect the hub sidewall and the back sidewall and are opposite to the outer periphery of the blade root. The opposing walls have a C-surface or a convex R-surface.

[0190] According to the centrifugal compressor impeller described in (18) above, the gap between the outer periphery of the blade root and the opposing wall can be tilted in the opposite direction relative to the flow direction. As a result, the mainstream inflow gap of the centrifugal compressor can be suppressed, gap loss can be reduced, and thus the efficiency of the centrifugal compressor can be improved.

[0191] (19) The centrifugal compressor of at least one embodiment of the present disclosure comprises:

[0192] The impeller of the centrifugal compressor described in (8) above;

[0193] The sidewalls of the shield and the sidewalls of the hub define diffusion paths (e.g., diffusion path 19 described above) through which the fluid compressed by the impeller of the centrifugal compressor flows.

[0194] The rear sidewall faces the rear side of the hub; wherein,

[0195] It also has opposing walls that connect the hub sidewall and the back sidewall and are opposite to the outer periphery of the hub. The opposing walls have a C-surface or a convex R-surface.

[0196] According to the centrifugal compressor impeller described in (19) above, the gap between the outer periphery of the hub and the opposing wall can be tilted in the opposite direction to the flow direction. As a result, the mainstream inlet gap of the centrifugal compressor can be suppressed, the gap loss can be reduced, and thus the efficiency of the centrifugal compressor can be improved.

[0197] (20) The centrifugal compressor of at least one embodiment of the present disclosure comprises:

[0198] The impeller of the centrifugal compressor described in any of (1) to (15) above;

[0199] A housing (e.g., housing 10 described above) that houses a bearing that provides shaft support for the impeller;

[0200] The at least one blade includes a blade root peripheral portion (e.g., the blade root peripheral portion 24 described above) connecting the hub side end of the trailing edge and the outer peripheral portion of the hub.

[0201] The outer periphery of the blade root extends parallel to the opposing wall surface in the outer shell that is opposite to the outer periphery of the blade root.

[0202] According to the centrifugal compressor described in (20) above, the outer periphery of the blade root extends parallel to the opposing wall surface in the casing that is opposite to the outer periphery of the blade root. Therefore, as the impeller rotates, the centrifugal force acts on the air near the inlet of the aforementioned gap, which can further improve the effect of suppressing the inflow of gap flow.

[0203] Explanation of reference numerals in the attached figures

[0204] 2. Turbocharger

[0205] 4. Centrifugal compressor

[0206] 5. Air Inlet

[0207] 6 Impeller

[0208] 7. Housing

[0209] 8. Protective Cover Section

[0210] 9. Vortex section

[0211] 10. Outer shell

[0212] 12-inch wheels

[0213] 12e Peripheral part

[0214] 13. Wheel hub surface

[0215] 13a Peripheral end

[0216] 14a Peripheral end

[0217] 14. Back

[0218] 15 blades

[0219] 16. Trailing edge

[0220] 16a Side of the protective cover

[0221] 16b wheel hub side end

[0222] 16c Central Department

[0223] 18 Airflow path

[0224] 19 Diffusion Flow Path

[0225] 20 Vortex Flow Path

[0226] 22 gap

[0227] 24. Outer periphery of leaf root

[0228] 26 Wheel hub sidewall

[0229] 27. Bend

[0230] 28. Back sidewall

[0231] 30-step surface (opposite wall)

[0232] 32 C side

[0233] 34 R side

[0234] 35 parts

[0235] 36 C face edge

[0236] 38 R face edge

[0237] 40 C side

[0238] 42 R face

[0239] 44 internal face

[0240] 46 curved surfaces

[0241] 48 Curved edge

[0242] 50 Sidewalls of the Protective Shield

Claims

1. An impeller for a centrifugal compressor, comprising a hub and at least one blade disposed on a hub surface of the hub, characterized in that, The hub-side end of the trailing edge of at least one blade is located radially outward compared to the outer periphery of the hub, and Located on a first line extending radially outward from the hub face of the hub, The shroud side end of the trailing edge of at least one blade is located radially outward compared to the outer periphery of the hub. The outer periphery of the hub has a C-surface or a concave R-surface formed in such a way that the back side is located radially outward compared to the front side of the hub.

2. The impeller of the centrifugal compressor as described in claim 1, wherein, The rear edge of the guard side is located radially outward compared to the hub side.

3. The impeller of the centrifugal compressor as described in claim 1, wherein, The rear edge of the guard side is located radially inward compared to the hub side.

4. The impeller of the centrifugal compressor as described in claim 1, wherein, The central portion of the rear edge is located radially outward compared to the side end of the rear edge guard and the side end of the wheel hub.

5. The impeller of the centrifugal compressor as described in claim 1, wherein, The at least one blade includes a blade root peripheral portion, which is the outer peripheral portion of the blade root connecting the hub side end of the trailing edge and the outer peripheral portion of the hub, and has a C-shaped edge or a concave R-shaped edge.

6. A centrifugal compressor comprising: The impeller of the centrifugal compressor as described in claim 1; The sidewalls of the shroud and the hub define a diffusion path through which the fluid compressed by the impeller of the centrifugal compressor flows; the centrifugal compressor is characterized in that... The width of the diffusion flow path at the hub side end of the trailing edge is set to W1. When the distance along the axial direction between the hub side end of the rear edge and the hub side wall is set as W2, 0.20≥W2 / W1 is satisfied.

7. A centrifugal compressor comprising: The impeller of the centrifugal compressor as described in claim 5; The sidewalls of the shield and the sidewalls of the hub define diffusion paths for the flow of fluid compressed by the impeller of the centrifugal compressor. The rear sidewall faces the rear side of the hub; the centrifugal compressor is characterized in that... It also has opposing walls that connect the hub sidewall and the back sidewall and are opposite to the outer periphery of the blade root. The opposing walls have a C-surface or a convex R-surface.

8. A centrifugal compressor comprising: The impeller of the centrifugal compressor as described in claim 1; The sidewalls of the shield and the sidewalls of the hub define diffusion paths for the flow of fluid compressed by the impeller of the centrifugal compressor. The rear sidewall faces the rear side of the hub; the centrifugal compressor is characterized in that... It also has opposing walls that connect the hub sidewall and the back sidewall and are opposite to the outer periphery of the hub. The opposing walls have a C-surface or a convex R-surface.

9. A centrifugal compressor, characterized in that, have: The impeller of the centrifugal compressor as described in claim 1; A housing that houses the bearings that provide shaft support for the impeller; The at least one blade includes a blade root outer periphery that connects the hub side end of the trailing edge and the outer periphery of the hub. The outer periphery of the blade root extends parallel to the opposing wall surface in the outer shell that is opposite to the outer periphery of the blade root.

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