Cover-equipped impeller, centrifugal compressor, and turbine

Abstract

To provide a cover-equipped impeller that is less subject to limitation by shape or size, and a centrifugal compressor and a turbine provided with the cover-equipped impeller.SOLUTION: A cover-equipped impeller 16 is configured to include a first split body 160 and a second split body 165 that are mechanically joined via a torque transmission section 172. The first split body 160 includes a first hub disc 161, a first cover disc 162, and a first blade section 163, integrally formed with one another. The second split body 165 includes a second hub disc 166, a second cover disc 167, and a second blade section 168, integrally formed with one another. The cover-equipped impeller 16 further comprises a hub-side sealing section 170 that provides sealing between the first hub disc 161 and the second hub disc 166, and a cover-side sealing section 171 that provides sealing between the first cover disc 162 and the second cover disc 167.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a covered impeller, a centrifugal compressor, and a turbine. [Background technology]

[0002] In manufacturing the impeller disclosed in Patent Document 1, the basic impeller and the auxiliary impeller ring are fitted together, and then the blades of both are aligned and the respective front and rear shrouds are integrated by welding.

[0003] In the manufacturing method of the shrouded impeller disclosed in Patent Document 2, blades of the inner diameter part and outer diameter part and a drive shaft hole through which the drive shaft is inserted are formed by machining. The fluid flow path in the impeller is formed by machining the blades. In this manufacturing method, the diameter part and outer diameter part are joined by diffusion bonding. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 52-144803 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-36444 Summary of the Invention [Problem to be solved by the invention]

[0005] However, it is believed that the technologies disclosed in Patent Documents 1 and 2 impose restrictions on the shape and size of the covered impeller. Specifically, with the technology disclosed in Patent Document 1, it is believed that it may be difficult to weld together the members on the inner surface side facing the fluid flow path, depending on the shape of the covered impeller to be manufactured.

[0006] Furthermore, the technology disclosed in Patent Document 2 attempts to join the outer diameter side part and the inner diameter side part by diffusion bonding, so it is thought that it would be difficult to manufacture a large-sized covered impeller.

[0007] The present invention has been made in consideration of the above problems, and has an object to provide a covered impeller that is less subject to restrictions due to shape and size, and a centrifugal compressor and turbine that include such a covered impeller. [Means for solving the problem]

[0008] A covered impeller according to one aspect of the present invention includes a first divided body and a second divided body, the second divided body being superimposed on the first divided body.

[0009] The first segment is integrally formed by a first hub disk, a first cover disk, and a first blade portion. The first hub disk is configured so that its outer peripheral surface gradually expands in diameter from a first end face on one side in the direction in which the rotation axis of the covered impeller extends to a second end face on the opposite side. The first cover disk has an inner peripheral surface that forms a first space between itself and the outer peripheral surface of the first hub disk, and surrounds the radially outer side of the first hub disk so that a first opening is formed between itself and the first hub disk on the one side. The first blade portion is connected to the outer peripheral surface of the first hub disk and the inner peripheral surface of the first cover disk, and is provided to circumferentially divide the first space.

[0010] The second segment is integrally formed by a second hub disk, a second cover disk, and a second blade portion. The second hub disk is configured so that its outer circumferential surface gradually expands in diameter from a third end face on one side in the direction in which the rotation axis extends to a fourth end face on the opposite side, and abuts against the second end face of the first hub disk. The second cover disk has an inner circumferential surface that forms a second space between itself and the outer circumferential surface of the second hub disk, and surrounds the radially outer side of the second hub disk so that a second opening is formed between itself and the second hub disk on the side of the second space opposite to the side that is continuous with the first space. The second blade portion is connected to the outer circumferential surface of the second hub disk and the inner circumferential surface of the second cover disk, and is provided to circumferentially divide the second space.

[0011] In the covered impeller according to this aspect, the side end of the first blade portion on the second segment side comes into contact with or is close to the side end of the second blade portion on the first segment side, thereby forming a single blade together with the second blade portion. Also, the end of the first cover disk on the second segment side comes into contact with or is close to the end of the second cover disk on the first segment side, thereby forming a single cover disk surrounding the single blade.

[0012] The covered impeller according to this aspect further includes a hub-side seal portion, a cover-side seal portion, and a torque transmission portion. The hub-side seal portion seals between the first hub disc and the second hub disc. The cover-side seal portion seals between the first cover disc and the second cover disc. The torque transmission portion mechanically joins at least one of the first hub disc and the second hub disc or the first cover disc and the second cover disc so as to transmit torque from the second segment to the first segment.

[0013] In the covered impeller according to the above aspect, the first segment and the second segment are mechanically joined by the torque transmission part. Therefore, the covered impeller according to the above aspect is less subject to restrictions due to shape and size compared to when shrouds are welded together as in Patent Document 1 or when parts are joined by diffusion bonding as in Patent Document 2. In other words, with the technology of Patent Document 1, depending on the shape of the covered impeller to be manufactured, it may be difficult to weld the members together on the inner surface side facing the fluid flow path.

[0014] Furthermore, when manufacturing a large-sized covered impeller with the technology of Patent Document 2, it is difficult to join the outer diameter side part and the inner diameter side part by diffusion bonding. In contrast, in the covered impeller according to the above embodiment, the first and second segments are joined by mechanical bonding, so it is less subject to the restrictions on shape and size that are present in the technologies of Patent Documents 1 and 2.

[0015] Furthermore, the covered impeller according to the above aspect employs a configuration in which the impeller is divided into a first segment and a second segment that are joined together. This allows the shapes of the first segment and the second segment to be set so that the first space and the second space, as well as the first blade portion and the second blade portion, can be easily processed. Therefore, the covered impeller according to the above aspect can avoid complicated work during manufacturing.

[0016] In the covered impeller according to the above aspect, the first blade portion and the second blade portion may be formed to have at least one of a positional relationship in which they are in contact with each other without any pressing force acting from one of the side ends of the first blade portion and the second blade portion to the other, and a positional relationship in which they are spaced apart so as to face each other with a gap of a predetermined dimension or less between the side ends.

[0017] In the covered impeller according to the above aspect, the first blade portion and the second blade portion are formed so that their side ends are in at least one of the contacting positional relationship and the spaced-apart positional relationship. Therefore, the covered impeller according to the above aspect can prevent deformation or damage to the first blade portion and the second blade portion due to the pressing force applied between the side ends of the first blade portion and the second blade portion. Furthermore, the covered impeller according to the above aspect can prevent performance loss due to a gap larger than a predetermined dimension being formed between the side ends of the first blade portion and the second blade portion.

[0018] In the covered impeller according to the above aspect, the predetermined dimension may be 1% of the outer diameter of the second blade portion.

[0019] In the covered impeller according to the above aspect, even when the side ends of the first blade portion and the second blade portion are arranged in the spaced-apart positional relationship, the gap between them is 1% or less of the outer diameter, which makes it possible to prevent performance impairment due to the gap between the side ends of the first blade portion and the second blade portion.

[0020] In the covered impeller according to the above aspect, of the side end portion of the first blade portion and the side end portion of the second blade portion, the side end portion located at least downstream in the flow direction of the fluid flowing along the one blade may be formed with a curved outer surface when viewed in cross section in the thickness direction of the blade portion located downstream.

[0021] In the covered impeller according to the above embodiment, the side end portion located at least downstream in the fluid flow direction (FL) is formed with a curved outer surface in cross section, so that even if the circumferential position is slightly misaligned during assembly, it is expected that there will be little loss of performance.

[0022] A centrifugal compressor according to one aspect of the present invention includes the covered impeller according to the above aspect, a casing, and a recovery unit. The casing houses the covered impeller. The recovery unit recovers gas discharged from the second opening due to rotation of the covered impeller.

[0023] The centrifugal compressor according to the above aspect includes the covered impeller according to the above aspect, and therefore can directly exert the effects of the covered impeller according to the above aspect.

[0024] A turbine according to one aspect of the present invention includes the covered impeller according to the above aspect, a casing, and an inlet portion, the casing housing the covered impeller, and the inlet portion allows gas to flow into the second opening.

[0025] The turbine according to the above aspect includes the covered impeller according to the above aspect, and therefore can directly exert the effects of the covered impeller according to the above aspect. [Effects of the Invention]

[0026] In each of the above aspects, it is possible to provide a covered impeller that is less subject to restrictions in terms of shape and size, and a centrifugal compressor and a turbine that include the covered impeller. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a perspective view showing a partial configuration of a centrifugal compressor according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing a configuration of a covered impeller included in the centrifugal compressor. [Figure 3] FIG. 3 is an enlarged cross-sectional view of part A in FIG. 2. [Figure 4] FIG. 4 is a cross-sectional view showing the configuration of a cross section taken along line IV-IV in FIG. [Figure 5] FIG. 10 is a cross-sectional view showing the configuration of the side end portions of the first blade portion and the second blade portion in a covered impeller according to a modified example. [Figure 6] FIG. 6 is a cross-sectional view showing the configuration of a turbine according to a second embodiment. [Figure 7] FIG. 10 is a cross-sectional view showing a modified example of the covered impeller. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the embodiments described below are merely illustrative of the present invention, and the present invention is not limited to the following embodiments except for the essential configuration.

[0029] [First embodiment] 1. Schematic configuration of centrifugal compressor 1 A schematic configuration of a centrifugal compressor 1 according to a first embodiment will be described with reference to Fig. 1. Note that Fig. 1 shows only a portion of the configuration of the centrifugal compressor 1.

[0030] As shown in Fig. 1, the centrifugal compressor 1 includes a covered impeller 16 and a gear case 10 that houses a mechanism that transmits a rotational driving force for rotating the covered impeller 16. A bull gear 11 and a pinion gear 12 are housed in a gear housing space 10a of the gear case 10. The bull gear 11 and the pinion gear 12 are arranged to mesh with each other.

[0031] A through hole is formed in the gear case 10. A gear shaft 12a of the pinion gear 12 is inserted into the through hole of the gear case 10. A covered impeller 16 is attached to the gear shaft 12a of the pinion gear 12 outside the gear case 10. The covered impeller 16 is housed in a space defined by the casing 13 and the casing cover 14.

[0032] The casing 13 and the casing cover 14 are configured to provide a space for accommodating the covered impeller 16, as well as a spiral-shaped recovery section (scroll section) 17 radially outward from the accommodating space. The casing 13 and the casing cover 14 are also configured to provide a diffuser between the space for accommodating the covered impeller 16 and the recovery section 17 in the radial direction, where the fluid discharged from the covered impeller 16 is decelerated and pressurized.

[0033] When the centrifugal compressor 1 is driven, the fluid to which kinetic energy is imparted by the rotation of the covered impeller 16 is discharged radially outward, decelerated and pressurized, and recovered in the recovery section 17 .

[0034] 2. Configuration of covered impeller 16 The configuration of the covered impeller 16 provided in the centrifugal compressor 1 will be described with reference to Fig. 2 and Fig. 3. Fig. 2 is a cross-sectional view showing the covered impeller 16 cut along a plane including its rotation axis Ax16. Fig. 3 is a cross-sectional view showing an enlarged view of part A in Fig. 2.

[0035] 2, the covered impeller 16 is attached to the gear shaft 12a of the pinion gear 12 using, for example, a tension bolt 18 and a nut 19. However, the method of attaching the covered impeller 16 to the gear shaft 12a is not limited to this.

[0036] The covered impeller 16 has a hub disk 16a, a cover disk 16b, and blades 16c. The covered impeller 16, which has the hub disk 16a, cover disk 16b, and blades 16c, is configured by combining a first divided body 160 and a second divided body 165 that are stacked together. The first divided body 160 is integrally formed with a first hub disk 161, a first cover disk 162, and first blade portions 163. The second divided body 165 is integrally formed with a second hub disk 166, a second cover disk 167, and second blade portions 168.

[0037] The hub disc 16a is composed of a first hub disc 161 of the first divided body 160 and a second hub disc 166 of the second divided body 165. The cover disc 16b is composed of a first cover disc 162 of the first divided body 160 and a second cover disc 167 of the second divided body 165. The blade 16c is composed of a first blade portion 163 of the first divided body 160 and a second blade portion 168 of the second divided body 165.

[0038] In the first divided body 160, each of the first hub disk 161, the first cover disk 162, and the first blade portion 163 is formed using a processing method such as cutting, EDM (Electrical Discharge Machining), metal shaping, etc. The same applies to the second divided body 165.

[0039] The first hub disc 161 has a cylindrical shape extending along the rotation axis Ax16. The outer circumferential surface 161c of the first hub disc 161 is configured so that the outer diameter gradually increases from one end face (first end face) 161a to the other end face (second end face) 161b in a cross section perpendicular to the rotation axis Ax16.

[0040] The inner circumferential surface 161d of the first hub disk 161 is configured so that the inner diameter is constant from the first end face 161a to the second end face 161b in a cross section perpendicular to the rotation axis Ax16. The portion of the first hub disk 161 that is surrounded by the inner circumferential surface 161d forms a through hole 161e. The through hole 161d of the first hub disk 161 is a hole through which the tension bolt 18 is inserted.

[0041] The first cover disk 162 has a cylindrical shape extending along the rotation axis Ax16. The first cover disk 162 surrounds the first hub disk 161 and forms a space (first space) 160a between the first cover disk 162 and the first hub disk 161. The outer diameter of the outer peripheral surface of the first cover disk 162 in a cross section perpendicular to the rotation axis Ax16 gradually increases from the first end face 161a side toward the second end face 161b side. The inner peripheral surface 162a of the first cover disk 162 is configured to surround the radial outside of the first hub disk 161, and is configured so that the inner diameter of the cross section perpendicular to the rotation axis Ax16 gradually increases from the first end face 161a side toward the second end face 161b side.

[0042] A first space 160a between the first hub disc 161 and the first cover disc 162 is open (first opening 160b) on the side of a first end face 161a of the first hub disc 161. The first opening 160b is open in a direction along the rotation axis Ax16.

[0043] 2 and 3, the first cover disk 162 has a protruding portion 162b that protrudes radially outward on the side opposite the first opening 160b in the direction in which the rotation axis Ax16 extends. The protruding portion 162b is formed to protrude in an annular shape around the entire circumference. A lower surface 162c of the protruding portion 162b (the surface facing the second cover disk 167) is formed to expand in a direction perpendicular to the rotation axis Ax16. A peripheral surface 162d that is formed along the direction in which the rotation axis Ax16 extends is connected to the radially inner side of the lower surface 162c.

[0044] 2 is connected to the outer peripheral surface 161c of the first hub disk 161 and the inner peripheral surface 162a of the first cover disk 162, and is provided so as to divide the first space 160a in the circumferential direction. One or more first blade portions 163 are provided in the circumferential direction.

[0045] The second hub disc 166 of the second divided body 165 has a circular plate shape with an opening at the center. The outer diameter of the outer peripheral surface 166c of the second hub disc 166 is configured to gradually increase from one end face (third end face) 166a to the other end face (fourth end face) 166b in a cross section perpendicular to the rotation axis Ax16. The outer peripheral surface 166c of the second hub disc 166 is configured so that the third end face 166a is approximately the same diameter as the outer diameter of the second end face 161b of the outer peripheral surface 161c of the first hub disc 161. The outer peripheral surface 166c of the second hub disc 166 is also formed to smoothly connect to the outer peripheral surface 161c of the first hub disc 161.

[0046] The inner circumferential surface 166d of the second hub disk 166 is configured so that the inner diameter is constant from the third end face 166a to the fourth end face 166b in a cross section perpendicular to the rotation axis Ax16. In the second hub disk 166, the portion surrounded by the inner circumferential surface 166d configures a through hole 166e. The through hole 166e of the second hub disk 166 is formed with the same diameter as the through hole 161d of the first hub disk 161. That is, in this embodiment, the tension bolt 18 is inserted through the through holes 161d and 166e, which are formed with the same diameter and are continuous with each other.

[0047] The second hub disk 166 is formed so that the entire circumference of the third end face 166a abuts against the second end face 161b of the first hub disk 161. That is, in the covered impeller 16, the first divided body 160 and the second divided body 165 are overlapped with each other, so that the first hub disk 161 and the second hub disk 166 form one hub disk 16a.

[0048] The second cover disk 167 has a cylindrical shape extending along the rotation axis Ax16. The second cover disk 167 surrounds the second hub disk 166 and forms a space (second space) 165a between the second cover disk 167 and the second hub disk 166. The outer diameter of the outer peripheral surface of the second cover disk 167 in a cross section perpendicular to the rotation axis Ax16 gradually increases from the third end face 166a side toward the fourth end face 166b side. The inner diameter of the inner peripheral surface 167a of the second cover disk 167 in a cross section perpendicular to the rotation axis Ax16 gradually increases from the third end face 166a side toward the fourth end face 166b side. The inner peripheral surface 167a of the second cover disk 167 is formed to smoothly connect to the inner peripheral surface 162a of the first cover disk 167.

[0049] The second space 165a between the second hub disk 166 and the second cover disk 167 is continuous with the first space 160a of the first divided body 160 and is open on the side opposite to the side continuous with the first space 160a (second opening 165b). The second opening 165b is open in a direction perpendicular to the rotation axis Ax16.

[0050] As shown in Figures 2 and 3, the second cover disk 167 has a protruding portion 167b formed on a portion of the second cover disk 167 closer to the first cover disk 167 in the direction in which the rotation axis Ax16 extends, and protruding along the direction in which the rotation axis Ax16 extends. The protruding portion 167b is formed in an annular shape around the entire circumference. In the covered impeller 16, the first cover disk 162 and the second cover disk 167 form a single hub disk 16b by overlapping the first divided body 160 and the second divided body 165. In this overlapping state, the protruding portion 167b is located inside the overhanging portion 162b.

[0051] A lower surface 162c of the overhanging portion 162b faces a surface 167c of the second cover disk 167 that is radially outer than the protruding portion 167b, with a gap therebetween in the direction in which the rotation axis Ax16 extends.

[0052] An upper surface 167e of the protrusion 167b (the surface on the first cover disk 162 side) is formed to expand in a direction perpendicular to the rotation axis Ax16. The upper surface 167e of the protrusion 167b faces a surface 162e of the first cover disk 162 that is radially inward of the overhanging portion 162b, with a gap therebetween, in the direction in which the rotation axis Ax16 extends.

[0053] Furthermore, a peripheral surface 167d formed along the direction in which the rotation axis Ax16 extends is connected to the radially outer side of the upper surface 167e of the protruding portion 167b. The peripheral surface 167d of the protruding portion 167b is formed so as to be in contact with the peripheral surface 162d of the protruding portion 167b of the first cover disk 162 over the entire circumference. That is, in the covered impeller 16, the overhanging portion 162b, which is the end of the first cover disk 162, and the protruding portion 167b, which is the end of the second cover disk 167, are in surface contact with each other.

[0054] The shapes of the protruding portion 162b of the first cover disc 162 and the protruding portion 167b of the second cover disc 167 shown in FIGS. 2 and 3 are merely examples, and various other shapes may be adopted.

[0055] 2 is connected to the outer peripheral surface 166c of the second hub disk 166 and the inner peripheral surface 167a of the second cover disk 167, and is provided to divide the second space 165a in the circumferential direction. The number of second blade portions 168 formed in the second segment 165 is the same as the number of first blade portions 163 formed in the first segment 160. In the covered impeller 16, the first segment 160 and the second segment 165 are overlapped, and the first blade portion 163 and the second blade portion 168 form one blade 16c. The one blade 16c is surrounded by one cover disk 16b.

[0056] The covered impeller 16 further includes a hub-side seal portion 170, a cover-side seal portion 171, and a torque transmission portion 172. The hub-side seal portion 170 is disposed in a recess provided in the second end face 161b of the first hub disk 161. An O-ring is used as the hub-side seal portion 170. However, seals of various shapes such as a C-seal, a leaf seal, or an omega seal may also be used. The hub-side seal portion 170 seals the gap between the second end face 161b of the first hub disk 161 and the third end face 166a of the second hub disk 166, thereby suppressing the movement of gas between the second end face 161b and the third end face 166a.

[0057] The cover-side seal 171 is disposed in a recess provided in the circumferential surface 167d of the protruding portion 167b of the second cover disk 167. An O-ring is used as the cover-side seal 171. However, various shapes such as a C-seal, a leaf seal, or an omega seal may also be used. The cover-side seal 171 seals the gap between the circumferential surface 162d of the protruding portion 162b of the first cover disk 162 and the circumferential surface 167d of the protruding portion 167b of the second cover disk 167, thereby suppressing the movement of gas at the boundary between the protruding portion 162b and the protruding portion 167b.

[0058] The torque transmission portion 172 mechanically joins at least one of the first hub disc 161 and the second hub disc 166 and the first cover disc 162 and the second cover disc 167 so as to be able to transmit torque from the second divided body 165 to the first divided body 160. In the present embodiment, as an example, the torque transmission portion 172 mechanically joins the first hub disc 161 and the second hub disc.

[0059] The torque transmission portion 172 may be, for example, a tooth coupling, a key, or a spline.

[0060] 3. Arrangement of the first blade portion 163 and the second blade portion 168 The arrangement of the first blade portion 163 and the second blade portion 163 will be described with reference to FIG.

[0061] The first blade portion 163 and the second blade portion 168 are arranged so that the side end portion 163a of the first blade portion 163 on the second divider 165 side is in contact with or close to the side end portion 168a of the second blade portion 168 on the first divider 160 side.

[0062] FIG. 3 shows a state in which a side end 163a of the first blade portion 163 and a side end 168a of the second blade portion 168 face each other with a gap G of a predetermined dimension or less therebetween.

[0063] However, the side end portions 163a of the first blade portions 163 and the side end portions 168a of the second blade portions 168 do not necessarily need to be disposed with the gap G therebetween, and may be in contact with each other over part or all of the circumferential direction. In other words, there may be a portion in the circumferential direction where the gap G=0. However, in the covered impeller 16 according to this embodiment, even when the gap G=0, no pressing force acts between the side end portions 163a and the side end portions 168a.

[0064] The dimension of the gap G is set to 1% or less of the outer diameter D168 (see FIG. 2) of the second blade portion 168. In other words, the upper limit value of the dimension of the gap G (the above-mentioned predetermined dimension) is 1% of the outer diameter D168 of the second blade portion 168.

[0065] By adopting the above-described arrangement, in the covered impeller 16, one blade 16c is configured from the first blade portion 163 and the second blade portion 168 as described above. Note that the covered impeller 16 may be additionally provided with a splitter blade in addition to the one blade 16c. In this case, the splitter blade does not necessarily need to be separated like the one blade 16c configured from the first blade portion 163 and the second blade portion 168.

[0066] 4. Positional relationship between openings 160b, 165b and side edges 163a, 168a The positional relationship between first opening 160b and second opening 165b and side end 163a of first blade portion 163 and side end 168a of second blade portion 168 will be described with reference to FIGS.

[0067] As shown in FIGS. 2 and 3, the side end 163a of the first blade portion 163 and the side end 168a of the second blade portion 168 are arranged to be inclined with respect to the rotation axis Ax16. As shown in FIG. 2, the side end 163a of the first blade portion 163 is arranged so that at least a portion thereof is visible when the first space 160a is viewed from the first opening 160b side. That is, the side end 163a of the first blade portion 163 is formed so that at least a portion thereof overlaps with the first opening 160b in the direction of the rotation axis Ax16. This makes it easier for a tool to reach the inside of the blank when creating the first divided body 160, making it easier to form the internal shape of the first divided body 160.

[0068] Furthermore, the side end portion 168a of the second blade portion 168 is arranged so that at least a portion thereof is visible when the second space 165a is viewed from the second opening portion 165b side. The side end portion 168a of the second blade portion 168 is formed so that at least a portion thereof overlaps with the second opening portion 165b in the radial direction (the direction perpendicular to the rotation axis Ax16). This makes it easier for a tool to reach the inside of the blank when creating the second divided body 165, and makes it easier to form the internal shape of the second divided body 165.

[0069] 5. Cross-sectional shapes of the side ends 163a, 168a of the blade portions 163, 168 The cross-sectional shapes of side end portion 163a of first blade portion 163 and side end portion 168a of second blade portion 168 will be described with reference to Figures 4 and 5. Figure 4 is a cross-sectional view showing the structure of the cross section taken along line IV-IV in Figure 3, and Figure 5 shows a modified example thereof.

[0070] 4, when the first blade portion 163 and the second blade portion 168 are viewed in cross section in the thickness direction, the side end portion 168a of the second blade portion 168 located downstream in the flow direction FL of the fluid flowing along one of the blades is formed with a curved outer surface. This makes it possible to suppress separation of the fluid at the side end portion 168a, and to suppress performance loss even if the circumferential positions of the first blade portion 163 and the second blade portion 168 are slightly misaligned during assembly.

[0071] On the other hand, in this embodiment, the outer surface of the side end 163a of the first blade portion 163 located upstream in the fluid flow direction FL is not curved but is rectangular. However, as shown in Fig. 5, both the side end 163a of the first blade portion 163 and the side end 168a of the second blade portion 168 may be formed with curved outer surfaces. In other words, it is sufficient that the outer surface of the side end 168a of the blade 168 located downstream in the fluid flow direction FL, out of the side end portions 163a, 168a of the blade portions 163, 168, is curved.

[0072] 4 and 5, in this embodiment, a circular shape is used as an example of the curved surface, but other shapes such as an elliptical shape may also be used. Also, it is possible to configure only the corners of the outer surfaces of the side ends 163a and 168a with rounded surfaces.

[0073] 6.Effects In the covered impeller 16 according to this embodiment, the first segment 160 and the second segment 168 are mechanically joined by the torque transmission portion 172. Therefore, the covered impeller 16 is less subject to shape and size restrictions than when shrouds are welded together as in Patent Document 1 or when parts are joined by diffusion bonding as in Patent Document 2. That is, with the technology of Patent Document 1, welding components together on the inner surface facing the fluid flow path can be difficult depending on the shape of the covered impeller to be manufactured. Furthermore, with the technology of Patent Document 2, it is difficult to join the outer diameter side part and the inner diameter side part by diffusion bonding when manufacturing a large-sized covered impeller. In contrast, with the covered impeller 16, the first segment 160 and the second segment 165 are joined by mechanical bonding, so the covered impeller 16 is less subject to shape and size restrictions like the technologies of Patent Documents 1 and 2.

[0074] Furthermore, the covered impeller 16 is configured to be divided into a first segment 160 and a second segment 165, which are joined together. This allows the shapes of the first segment 160 and the second segment 165 to be set so that the first space 160a and the second space 165b, as well as the first blade portion 163 and the second blade portion 168, can be easily processed. Therefore, the covered impeller 16 can avoid complicated work during manufacturing. Specifically, when attempting to construct a covered impeller using a single member, problems may arise, such as high processing costs and difficulty, and tools being unable to reach the blade portion or opening depending on the shape.

[0075] In contrast, the covered impeller 16 according to this embodiment employs a configuration in which the first division 160 and the second division 165 are assembled after the first division 160 and the second division 165 are formed, thereby eliminating the above-mentioned problems. Furthermore, the configuration of the covered impeller 16 according to this embodiment can also be used when the parts are large and complex.

[0076] In the covered impeller 16 according to this embodiment, the first blade portion 163 and the second blade portion 168 are formed so that the side ends 163a, 168a are in contact with or close to each other. The covered impeller 16 is configured so that when the side ends 163a, 168a are in contact with each other, no pressing force acts on them. The covered impeller 16 is also configured so that when the side ends 163a, 168a are close to each other, the gap G between them is equal to or smaller than a predetermined dimension.

[0077] By adopting the above-described configuration, the covered impeller 16 can suppress deformation and damage of the blade portions 163, 168 caused by the side ends 163a, 168a of the first blade portion 163 and the second blade portion 168 applying pressure to each other. Also, the covered impeller 16 can suppress performance loss caused by a gap larger than a predetermined dimension being formed between the side ends 163a, 168a of the first blade portion 163 and the second blade portion 168.

[0078] Furthermore, in the covered impeller 16 according to this embodiment, the upper limit (predetermined dimension) of the gap G between the side ends 163a, 168a is set to 1% of the outer diameter D168 of the second blade portion 168. Therefore, in the covered impeller 16, even if a gap G is formed between the side ends 163a, 168a of the first blade portion 168 and the second blade portion 168, performance impairment due to turbulence in the fluid flow in the gap G can be suppressed.

[0079] Furthermore, the centrifugal compressor 1 according to this embodiment includes the covered impeller 16 that can achieve the effects described above, and therefore can achieve the same effects as those described above.

[0080] [Second embodiment] A turbine 2 according to a second embodiment will be described with reference to FIG.

[0081] The turbine 2 according to this embodiment is a steam turbine that is driven by steam to serve as a power source for the centrifugal compressor 1, and is provided as a part of the centrifugal compressor 1.

[0082] As shown in Fig. 6, the turbine 2 is attached to the gear case 10 of the centrifugal compressor 1. A bull gear 11 and a pinion gear 12 are accommodated in the gear accommodating space 10a of the gear case 10. The configurations of the bull gear 11 and the pinion gear 12 are the same as those in the first embodiment.

[0083] A gear shaft 12a of the pinion gear 12 is inserted into each through-hole of the gear case 10. A covered impeller 16a is attached to the gear shaft 12a of the pinion gear 12 outside the gear case 10. The covered impeller 16a is housed in a space defined by the casing 13 and the casing cover 14.

[0084] Each of the covered impellers 16 provided in the turbine 2 has the same configuration as the covered impeller 16 in the first embodiment. Also, in this embodiment, as an example of a method for attaching the covered impeller 16a to the gear shaft 12a, the covered impeller 16a is attached using a tension bolt 18 and a nut 19. However, the method for attaching the covered impeller 16a to the gear shaft 12a is not limited to this.

[0085] The space defined by the casing 13 and the casing cover 14 has an inlet section 27 provided on the outer periphery thereof in addition to the space in which the covered impeller 16 is housed. The inlet section 27 is an area through which steam flows into the second opening 165b (see FIG. 2) of the covered impeller 16a.

[0086] In the turbine 2, the covered impeller 16a is rotated by the fluid flowing in from the second opening 165b, and the rotational energy thereof drives the covered impeller 16a of the centrifugal compressor 1 via the pinion gear 12 and the bull gear 11.

[0087] The turbine 2 according to this embodiment includes a covered impeller 16a having the same configuration as that of the first embodiment, and therefore can achieve the same effects as those of the first embodiment.

[0088] In the first embodiment, the side end 168a of the second blade portion 168 located downstream in the fluid flow direction FL is formed with a curved outer surface in cross section (see FIG. 4). In contrast, in the present embodiment, the fluid flow direction FL is the direction from the second opening 165b toward the first opening 160b, so the same effect as above can be achieved by forming the outer surface of at least the side end 163a of the first blade portion 163 in cross section as a curved surface. Of course, the configuration described using FIG. 5 can also be used.

[0089] It should be noted that the embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The present invention is not limited to the above-described embodiments, and various modifications and improvements are possible without departing from the spirit and scope of the present invention.

[0090] [Variations] In the first and second embodiments, the first lower surface 162c of the first cover disk 162 may be in contact with the surface 167c of the second cover disk 167 that is radially outer than the protruding portion 167b over the entire circumference. Similarly, the upper surface 167e of the protruding portion 167b of the second cover disk 167 may be in contact with the surface 162e of the first cover disk 162 that is radially inner than the protruding portion 162b over the entire circumference.

[0091] The cover-side seal portion 171 may be disposed in a recess provided in the peripheral surface 162d of the protruding portion 162b of the first cover disk 162. The hub-side seal portion 170 may be disposed in a recess provided in the third end face 166a of the second hub disk 166.

[0092] As shown in FIG. 7, the protruding portion 162b of the first cover disk 162 may be located radially inward of the protruding portion 167b of the second cover disk 167.

[0093] A structure similar to the covered impeller 16 used in the first embodiment can also be applied to a covered impeller of a centrifugal pump.

[0094] The turbine 2 of the second embodiment may be provided independently of the centrifugal compressor 1. A structure similar to the covered impeller 16a used in the turbine 2 can also be applied to other turbines such as gas turbines and hydraulic turbines. [Explanation of symbols]

[0095] 1. Centrifugal compressor 2 turbines 13 Casing 16 Impeller with cover 17 Recovery Department 27 Inlet 160 1st division body 161 First hub disc 162 1st Cover Disc 163 First Blade Section 163a Side edge 165 Second division body 166 Second hub disc 167 Second Cover Disc 168 Second Blade Section 168a Side edge 170 Hub side seal 171 Cover side seal 172 Torque transmission section

Claims

1. A covered impeller (16), a first divided body (160); a second divided body (165) that is superimposed on the first divided body (160); Equipped with The first divided body (160) a first hub disk (161) configured such that an outer peripheral surface (161c) gradually expands in diameter from a first end surface (161a) on one side in a direction in which a rotation axis (Ax16) of the covered impeller (16) extends to a second end surface (161b) on the opposite side; a first cover disk (162) having an inner peripheral surface (162a) that forms a first space (160a) between itself and the outer peripheral surface (161c) of the first hub disk (161), and surrounding the radially outer side of the first hub disk (161) so that a first opening (160b) is formed between itself and the first hub disk (161) on the one side; a first blade portion (163) connected to the outer peripheral surface (161c) of the first hub disk (161) and the inner peripheral surface (162a) of the first cover disk (162) and provided to divide the first space (160a) in the circumferential direction; are integrally formed by The second divided body (165) a second hub disk (166) configured such that an outer circumferential surface (166c) gradually increases in diameter from a third end surface (166a) on one side in the direction in which the rotation axis (Ax16) extends to a fourth end surface (166b) on the opposite side, and abutting against the second end surface (161b) of the first hub disk (161); a second cover disk (167) having an inner peripheral surface (167a) that forms a second space (165a) between itself and the outer peripheral surface (166c) of the second hub disk (166), and surrounding the radially outer side of the second hub disk (166) so that a second opening (165b) is formed between itself and the second hub disk (166) on the side of the second space (165a) opposite to the side that is continuous with the first space (160a); a second blade portion (168) connected to the outer peripheral surface (166c) of the second hub disk (166) and the inner peripheral surface (167a) of the second cover disk (167) and provided to divide the second space (165a) in the circumferential direction; are integrally formed by a side end (163 a) of the first blade portion (163) on the side of the second divided body (165) comes into contact with or is close to a side end (168 a) of the second blade portion (168) on the side of the first divided body (160), whereby the first blade portion (163) and the second blade portion (168) form one blade (16 c); an end (162b) of the first cover disk (162) on the side of the second divided body (165) contacts or comes close to an end (167b) of the second cover disk (167) on the side of the first divided body (160), thereby forming one cover disk (16b) surrounding one blade (16c); a hub-side seal portion (170) that seals between the first hub disk (161) and the second hub disk (166); a cover-side seal portion (171) that seals the gap between the first cover disk (162) and the second cover disk (167); a torque transmission portion (172) that mechanically connects at least one of the first hub disk (161) and the second hub disk (166) or the first cover disk (162) and the second cover disk (167) so as to be able to transmit torque from the second divided body (165) to the first divided body (160); The covered impeller (16) further comprises:

2. 2. The covered impeller (16) according to claim 1, wherein the first blade portion (163) and the second blade portion (168) are formed to have at least one of the following positional relationships: a positional relationship in which the first blade portion (163) and the second blade portion (168) are in contact with each other without any pressing force acting from one of the side end portions (163 a) of the first blade portion (163) and the side end portion (168 a) of the second blade portion (168 a) to the other side end portion; and a positional relationship in which the side end portions (163 a, 168 a) are spaced apart so as to face each other with a gap (G) of a predetermined dimension or less between them.

3. 3. The covered impeller (16) according to claim 2, wherein the predetermined dimension is 1% of the outer diameter (D168) of the second blade portion (168).

4. 4. The covered impeller (16) according to claim 1, wherein, of the side end (163 a) of the first blade portion (163) and the side end (168 a) of the second blade portion (168), the side end (168 a) located at least downstream in the flow direction (FL) of the fluid flowing along the one blade is formed with a curved outer surface when viewed in cross section in the thickness direction of the blade portion (168) located downstream.

5. A covered impeller (16) according to claim 1; a casing (13) that houses the covered impeller; a recovery section (17) that recovers gas discharged from the second opening (165b) by rotation of the covered impeller (16); A centrifugal compressor (1) comprising:

6. A covered impeller (16) according to claim 1; a casing (13) that houses the covered impeller (16); an inlet (27) for allowing gas to flow into the second opening (165b); A turbine (2).

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