compressor

Abstract

To improve productivity. [Solution] The compressor comprises an impeller housing having a first housing 41 housing a first impeller 31 and a second housing 42 housing a second impeller 32, and an interstage housing 44 connected to the impeller housing and, together with the impeller housing, forming an interstage passage 60 for introducing fluid from the first impeller 31 to the second impeller 32. The interstage passage 60 has at least one curved passage 63. The curved passage 63 includes an inner circumferential wall surface 63a that curves on the inner side in a cross section passing through the center line CL of the curved passage 63, and an outer circumferential wall surface 63b that curves on the outer side in the same cross section. The inner circumferential wall surface 63a is formed in the impeller housing. The outer circumferential wall surface 63b is formed in the interstage housing 44. The distance between the outer circumferential wall surface 63b and the inner circumferential wall surface 63a is constant at each position along the extending direction of the center line CL.

Description

Technical Field

[0001] The present disclosure relates to a compressor.

Background Art

[0002] Patent Documents 1 to 3 disclose techniques related to compressors. As such a compressor, a multistage compressor having two or more compression stages is known. The multistage compressor includes, for example, a front-stage compression stage that sucks and compresses a fluid, and a rear-stage compression stage that further compresses the fluid compressed by the front-stage compression stage. In such a multistage compressor, generally, the front-stage compression stage and the rear-stage compression stage are connected by piping, and the fluid from the front-stage compression stage is introduced into the rear-stage compression stage through the flow path in the piping.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a configuration in which the front-stage compression stage and the rear-stage compression stage are connected by piping, man-hours for assembling the piping to these compression stages are required. Furthermore, in addition to the cost of the piping itself, a cost corresponding to the assembly man-hours is incurred, so the mass production cost tends to be high. Therefore, it is difficult to improve the productivity of the compressor with the above-described configuration.

[0005] The present disclosure describes a compressor capable of improving productivity.

Means for Solving the Problems

[0006] A compressor according to one embodiment of the present disclosure further compresses a fluid compressed by a first impeller with a second impeller. The compressor comprises an impeller housing having a first housing for housing a first impeller and a second housing for housing a second impeller, and an interstage component connected to the impeller housing and, together with the impeller housing, forming an interstage passage for introducing fluid from the first impeller to the second impeller. The interstage passage has at least one curved passage. The curved passage includes an inner circumferential side wall surface that curves on the inner side in a cross-section passing through the centerline of the curved passage, and an outer circumferential side wall surface that curves on the outer side in a cross-section. One of the inner circumferential side wall surface and the outer circumferential side wall surface is formed in the impeller housing. The other of the inner circumferential side wall surface and the outer circumferential side wall surface is formed in the interstage component. The distance between the inner circumferential side wall surface and the outer circumferential side wall surface in a direction perpendicular to the centerline is constant at each position along the centerline. [Effects of the Invention]

[0007] According to some aspects of this disclosure, a compressor capable of improving productivity is provided. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a cross-sectional view showing a compressor according to one embodiment. [Figure 2] Figure 2 is an enlarged cross-sectional view of the compression unit of the compressor shown in Figure 1. [Figure 3] Figure 3 is an enlarged cross-sectional view of a portion of the interstage flow path of the compression unit shown in Figure 1. [Figure 4] Figure 4(a) is a cross-sectional view of the interstage channel along the line A1-A1 in Figure 3. Figure 4(b) is a cross-sectional view of the interstage channel along the line A2-A2 in Figure 3. [Figure 5] Figure 5 is a cross-sectional view of the compression unit, showing the individual components of the compression unit as shown in Figure 2. [Figure 6] Figure 6 is an enlarged cross-sectional view of the compression unit according to the comparative example. [Figure 7]Figure 7(a) is an enlarged cross-sectional view of a portion of the compression unit according to Reference Example 1. Figure 7(b) is an enlarged cross-sectional view of a portion of the compression unit according to Reference Example 2. [Figure 8] Figure 8(a) is an enlarged cross-sectional view of a portion of the compression unit according to Reference Example 3. Figure 8(b) is an enlarged cross-sectional view of a portion of the compression unit according to Reference Example 4. [Figure 9] Figure 9 is an enlarged cross-sectional view of a part of the compression unit according to Modification 1. [Figure 10] Figure 10 is an enlarged cross-sectional view of a part of the compression unit according to Modification 2. [Modes for carrying out the invention]

[0009] A compressor according to one embodiment of the present disclosure further compresses a fluid compressed by a first impeller with a second impeller. The compressor comprises an impeller housing having a first housing for housing a first impeller and a second housing for housing a second impeller, and an interstage component connected to the impeller housing and, together with the impeller housing, forming an interstage passage for introducing fluid from the first impeller to the second impeller. The interstage passage has at least one curved passage. The curved passage includes an inner circumferential wall surface that curves on the inner side in a cross-section passing through the centerline of the curved passage, and an outer circumferential wall surface that curves on the outer side in a cross-section. One of the inner circumferential wall surface and the outer circumferential wall surface is formed in the impeller housing. The other of the inner circumferential wall surface and the outer circumferential wall surface is formed in the interstage component.

[0010] In the compressor described above, the interstage passage that introduces fluid from the first impeller to the second impeller is formed by the impeller housing and the interstage component. One of the inner and outer side walls of the curved passage of the interstage passage is formed in the impeller housing, and the other is formed in the interstage component. In other words, the inner and outer side walls of the curved passage are formed in separate housings. In this case, unlike when the inner and outer side walls are formed in a single housing, the formation of overhangs in each component can be avoided, making it possible to mold each component. This makes it possible to mold each component using die casting, which has a low manufacturing cost. Furthermore, in the above configuration, the process of separately preparing piping for the interstage passage and assembling it to the impeller housing can be eliminated, thus reducing assembly man-hours. Therefore, the above compressor makes it possible to improve productivity and suppress mass production costs.

[0011] In some embodiments, the boundary line indicating the boundary between the impeller housing and the interstage component in the above cross-section may have a first boundary line and a second boundary line between the inner circumferential side wall and the outer circumferential side wall. The first boundary line may extend so as to intersect a straight line connecting the starting end of the inner circumferential side wall and the starting end of the outer circumferential side wall. The second boundary line may extend so as to intersect a straight line connecting the end of the inner circumferential side wall and the end of the outer circumferential side wall. The second boundary line may be directly or indirectly connected to the first boundary line between the inner circumferential side wall and the outer circumferential side wall. In this case, it becomes possible to set the boundary line according to the shape of the inner circumferential side wall and the outer circumferential side wall, so there is no need to make adjustments such as changing the shape of the inner circumferential side wall and the outer circumferential side wall to match the boundary line. As a result, it is possible to avoid situations in which changes occur in each cross-section of the curved flow path due to changes in the shape of the inner circumferential side wall and the outer circumferential side wall. This makes it possible to suppress situations in which pressure loss occurs in the fluid flowing through the curved flow path and suppress the deterioration of compressor performance.

[0012] In some embodiments, the distance between the inner peripheral side wall surface and the outer peripheral side wall surface in a direction perpendicular to the center line may be constant at each position along the center line. In this case, it is possible to suppress a situation where a change in cross-sectional area occurs in each flow path cross-section of the bent flow path. Thereby, it is possible to suppress a situation where a pressure loss occurs in the fluid flowing through the bent flow path, and it is possible to suppress a deterioration in the performance of the compressor.

[0013] In some embodiments, in a cross-section perpendicular to the center line of the bent flow path, the inner peripheral side wall surface may extend linearly. The outer peripheral side wall surface may be curved so as to bulge from the inner peripheral side wall surface toward the side opposite to the inner peripheral side wall surface. In this case, die casting can be easily performed with the direction from the outer peripheral side wall surface toward the inner peripheral side wall surface as the blanking direction.

[0014] In some embodiments, the inter-stage component may be an inter-stage housing that is connected in series to the first housing via the second housing. The inner peripheral side wall surface may be formed in the second housing. The outer peripheral side wall surface may be formed in the inter-stage component. In this case, an inter-stage flow path can be easily formed by a simple operation of connecting the inter-stage housing, the second housing, and the first housing in series. Further, since the inner peripheral side wall surface and the outer peripheral side wall surface are formed separately in the second housing and the inter-stage component in this way, it becomes possible to perform blanking of the second housing and the inter-stage housing.

[0015] In some embodiments, the inter-stage component may be an inter-stage plate sandwiched between the first housing and the second housing. The inner peripheral side wall surface may be formed in the inter-stage component. The outer peripheral side wall surface may be formed in the first housing. In this case, an inter-stage flow path can be easily formed by using the inter-stage plate between the first housing and the second housing. Further, since the inner peripheral side wall surface and the outer peripheral side wall surface are formed separately in the inter-stage plate and the first housing in this way, it becomes possible to perform blanking of the inter-stage plate and the first housing.

[0016] In some embodiments, the first wall surface and the second wall surface may extend parallel to each other in a cross-section passing through the center line and may be formed in the impeller housing. In this case, by setting the direction in which the straight flow path extends as the die-cutting direction, it becomes possible to perform die-cutting of the impeller housing in which the straight flow path is formed. Therefore, even in the case of the inter-stage flow path having the curved flow path and the straight flow path as described above, it becomes possible to perform die-cutting of each component.

[0017] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the description of the drawings, the same reference numerals are assigned to the same elements, and duplicate descriptions are omitted as appropriate.

[0018] The compressor 1 shown in FIG. 1 is, for example, an in-line two-stage compressor. The compressor 1 includes a shaft 10, a compression unit 30, and a motor unit 50. The compression unit 30 includes a first impeller 31, a second impeller 32, and an impeller housing 33. The first impeller 31 and the second impeller 32 are attached to one end of the shaft 10. The first impeller 31 and the second impeller 32 are arranged such that, for example, their backs face each other with a gap therebetween. The first impeller 31 is arranged coaxially with the second impeller 32, for example. The first impeller 31 is located between the second impeller 32 and the motor unit 50, for example.

[0019] The impeller housing 33 includes a first housing 41 that houses the first impeller 31 and a second housing 42 that houses the second impeller 32. The second housing 42 is connected in series to the first housing 41 in the axial direction D1 in which the shaft 10 extends. The first impeller 31 and the first housing 41 constitute a low-pressure compression stage that sucks and compresses the fluid R. The second impeller 32 and the second housing 42 constitute a high-pressure compression stage that further compresses the fluid R compressed by the low-pressure compression stage.

[0020] The compression unit 30 further comprises an interstage plate 43 and an interstage housing 44. The interstage plate 43 and the interstage housing 44 are interstage components connected to the impeller housing 33. Together with the impeller housing 33, the interstage plate 43 and the interstage housing 44 form an interstage flow path 60 that introduces fluid R from the first impeller 31 of the low-pressure compression stage to the second impeller 32 of the high-pressure compression stage. The interstage plate 43 is a plate-shaped component sandwiched between the first housing 41 and the second housing 42. The interstage housing 44 is a housing component connected to the second housing 42 in the axial direction D1 from the opposite side from the first housing 41. The interstage housing 44 is connected in series with the first housing 41 in the axial direction D1 via the second housing 42 and the interstage plate 43. Therefore, the interstage housing 44, the second housing 42, the interstage plate 43, and the first housing 41 are connected in series with each other in the axial direction D1. The statement that each component is connected in series in the axial direction D1 means that each component is aligned in the axial direction D1 and that each component has a connecting surface that intersects in the axial direction D1. In this embodiment, the interstage plate 43, the first housing 41, and the second housing 42 are separately provided members. That is, the interstage plate 43, the first housing 41, and the second housing 42 are each independent and separate parts. The compression unit 30 is formed by integrating the interstage plate 43, the first housing 41, and the second housing 42. As means for integrating the interstage plate 43, the first housing 41, and the second housing 42, known fastening means such as screws or bolts and nuts, or known joining means such as welding or fusion joining can be used.

[0021] The motor unit 50 comprises a motor 51 and a motor housing 52. The motor 51 is a power source for driving the compression unit 30. The motor 51 is mounted on the other end of the shaft 10. Inside the motor housing 52, the shaft 10 is rotatably supported by bearings. The motor housing 52 houses the motor 51. The motor housing 52 is connected in series with the first housing 41 in the axial direction D1. The motor housing 52, the first housing 41, the interstage plate 43, the second housing 42, and the interstage housing 44 are each separate and independent parts, and their combination constitutes the housing of the compressor 1.

[0022] Figure 2 shows a magnified view of the compression unit 30. As shown in Figure 2, the first housing 41 includes an intake port 41a, a diffuser passage 41b, and a scroll passage 41c. The intake port 41a is an opening coaxial with the shaft 10 and communicates with the inside of the motor housing 52 (see Figure 1). Fluid R drawn in from the intake port of the motor housing 52 flows into the intake port 41a. The first impeller 31 is located behind the intake port 41a. The rotation of the first impeller 31 imparts kinetic energy to the fluid R. The scroll passage 41c is formed to surround the first impeller 31. The diffuser passage 41b is formed between the first impeller 31 and the scroll passage 41c. The diffuser passage 41b compresses the fluid R by converting the kinetic energy imparted to the fluid R into compression energy. The scroll passage 41c discharges the fluid R that has been compressed in the diffuser passage 41b.

[0023] The second housing 42 includes an inlet 42a, a diffuser passage 42b, a scroll passage 42c, and an outlet 42d. The inlet 42a is a coaxial opening with the inlet 41a of the first housing 41 and faces away from the inlet 41a. The inlet 42a is connected to the scroll passage 41c of the first housing 41 via an interstage passage 60. Thus, fluid R from the scroll passage 41c flows into the inlet 42a via the interstage passage 60. The second impeller 32 is located behind the inlet 42a. The rotation of the second impeller 32 imparts kinetic energy to the fluid R. The scroll passage 42c is formed to surround the second impeller 32. The diffuser passage 42b is formed between the second impeller 32 and the scroll passage 42c. The diffuser passage 42b further compresses the fluid R by converting the kinetic energy imparted to the fluid R into compression energy. The scroll channel 42c discharges the compressed fluid R to the outside through the discharge port 42d.

[0024] Next, the configuration of the interstage flow path 60 will be described in detail. In the following description, "upper" means the upper side of the vertical direction D2 when the compressor 1 is installed at the place of use, and "lower" means the lower side of the vertical direction D2. In this embodiment, when the compressor 1 is installed at the place of use, the shaft 10 is arranged to extend in the horizontal direction. Therefore, in this embodiment, the axial direction D1 is perpendicular to the vertical direction D2.

[0025] The interstage flow channels 60 include, for example, a curved flow channel 61, a straight flow channel 62, a curved flow channel 63, a straight flow channel 64, and a curved flow channel 65. These flow channels are formed on the same plane. That is, the centerlines CL of these flow channels are contained within the same plane. Here, the same plane may be, for example, a plane along the axial direction D1 and the vertical direction D2. The centerline CL of the interstage flow channels 60 may be a line passing through the centroid of each flow channel cross-section perpendicular to the extension direction of the interstage flow channels 60. Figure 2 shows a cross-section of the compression unit 30 when cut through a plane along the axial direction D1 and the vertical direction D2, passing through the centerline CL. In this embodiment, the curved flow channels 61, straight flow channels 62, curved flow channels 63, straight flow channels 64, and curved flow channels 65 constituting the interstage flow channels 60 are arranged in this order from upstream to downstream in the flow direction of the fluid R flowing through the interstage flow channels 60.

[0026] The straight channel 62 is located below the second impeller 32 and extends in the axial direction D1. For example, the straight channel 62 extends parallel to the shaft 10. The curved channel 61 is located below the first impeller 31 and extends in an arc between the outlet 41d of the scroll channel 41c and the straight channel 62. That is, the curved channel 61 extends below the outlet 41d of the scroll channel 41c and curves to connect with the straight channel 62 in the axial direction D1. The curved channels 63, 64, and 65 are located on the opposite side of the second impeller 32 from the first impeller 31 in the axial direction D1.

[0027] The straight channel 64 extends linearly in the vertical direction D2, above the straight channel 62 and below the shaft 10. The curved channel 63 is located on the opposite side of the curved channel 61 from the straight channel 62 in the axial direction D1. The curved channel 63 extends in an arc between the straight channel 62 and the straight channel 64. In other words, the curved channel 63 curves upward from the straight channel 62 and connects to the straight channel 64. The curved channel 65 is located on the opposite side of the curved channel 63 from the straight channel 62 in the vertical direction D2. The curved channel 65 extends in an arc between the straight channel 64 and the intake port 42a. In other words, the curved channel 65 curves upward from the straight channel 64 and connects to the intake port 42a in the axial direction D1.

[0028] The curved channels 61, 63, and 65, for example, have the same curvature. The curvature here may be based on the center line CL of each curved channel. In this embodiment, the "curved channel" is a continuous curved section of the interstage channel 60 represented by one curvature in the cross-section shown in Figure 2. The curved channels 61, 63, and 65 may have different curvatures. The curved channels 61, 63, and 65 may be directly connected to each other without a straight channel in between. As described later, the curved channels 61, 63, and 65 in this embodiment are formed by a combination of the first housing 41, the interstage plate 43, the second housing 42, and the interstage housing 44. In this embodiment, the curved channels 61, 63, and 65 consist only of curved sections in the cross-section shown in Figure 2. However, the curved channels 61, 63, and 65 are not limited to this form and may include, for example, channels extending in a straight line at the starting end, the ending end, or between the starting and ending ends of each curved channel.

[0029] The configuration of each channel in the interstage channel 60 will be described in more detail. The curved channel 61 includes an inner circumferential wall surface 61a that constitutes the inner circumferential wall surface of the curved channel 61, and an outer circumferential wall surface 61b that constitutes the outer circumferential wall surface of the curved channel 61. In the cross-section shown in Figure 2, the inner circumferential wall surface 61a and the outer circumferential wall surface 61b are represented as arc-shaped curves. The inner circumferential wall surface 61a is curved in an arc shape at its inner circumferential position, i.e., radially inward from the outer circumferential wall surface 61b. The outer circumferential wall surface 61b is curved in an arc shape at its outer circumferential position, i.e., radially outward from the inner circumferential wall surface 61a.

[0030] The outer peripheral wall surface 61b is, for example, arranged concentrically with the inner peripheral wall surface 61a and extends parallel to the inner peripheral wall surface 61a. The inner peripheral wall surface 61a may be the portion of the wall surface constituting the curved flow channel 61 that includes at least the arc-shaped curved portion on the inner side shown in Figure 2. The outer peripheral wall surface 61b may be the portion of the wall surface constituting the curved flow channel 61 that includes at least the arc-shaped curved portion on the outer side shown in Figure 2. The outer peripheral wall surface 61b may be the portion excluding the inner peripheral wall surface 61a. The starting end Pa of the inner peripheral wall surface 61a and the starting end Pb of the outer peripheral wall surface 61b are connected to the wall surface constituting the outlet 41d of the scroll flow channel 41c. In this specification, the starting end of a wall surface means one end of the wall surface located on the upstream side in the flow direction of the fluid R flowing through the interstage flow channel 60 in the cross-section shown in Figure 2. The term "end of a wall" refers to the other end of that wall located downstream in the direction of flow.

[0031] The curved channel 63 includes an inner circumferential wall surface 63a that constitutes the inner circumferential wall surface of the curved channel 63, and an outer circumferential wall surface 63b that constitutes the outer circumferential wall surface of the curved channel 63. In the cross-section shown in Figure 2, the inner circumferential wall surface 63a and the outer circumferential wall surface 63b are represented as arc-shaped curves. The inner circumferential wall surface 63a is curved in an arc shape at an inner circumferential position, i.e., radially inward from the outer circumferential wall surface 63b. The outer circumferential wall surface 63b is curved in an arc shape at an outer circumferential position, i.e., radially outward from the inner circumferential wall surface 63a. The outer circumferential wall surface 63b is arranged concentrically with the inner circumferential wall surface 63a and extends parallel to the inner circumferential wall surface 63a. The inner circumferential wall surface 63a may be a portion of the wall surface constituting the curved channel 63 that includes at least the arc-shaped curved portion on the inner circumferential side shown in Figure 2. The outer peripheral wall surface 63b may be the portion of the wall surface constituting the curved channel 63 that includes at least the outer arc-shaped curved portion shown in Figure 2. The outer peripheral wall surface 63b may be the portion excluding the inner peripheral wall surface 63a.

[0032] The curved channel 65 includes an inner circumferential wall surface 65a that constitutes the inner circumferential wall surface of the curved channel 65, and an outer circumferential wall surface 65b that constitutes the outer circumferential wall surface of the curved channel 65. In the cross-section shown in Figure 2, the inner circumferential wall surface 65a and the outer circumferential wall surface 65b are represented as arc-shaped curves. The inner circumferential wall surface 65a is curved in an arc shape at an inner circumferential position, i.e., radially inward from the outer circumferential wall surface 65b. The outer circumferential wall surface 65b is curved in an arc shape at an outer circumferential position, i.e., radially outward from the inner circumferential wall surface 65a. The outer circumferential wall surface 65b is arranged concentrically with the inner circumferential wall surface 65a and extends parallel to the inner circumferential wall surface 65a. The inner circumferential wall surface 65a may be the portion of the wall surface constituting the curved channel 65 that includes at least the arc-shaped curved portion on the inner circumferential side shown in Figure 2. The outer peripheral wall surface 65b may be the portion of the wall surface constituting the curved flow path 65 that includes at least the outer-circumferential arc-shaped curved portion shown in Figure 2. The outer peripheral wall surface 65b may be the portion of the wall surface excluding the inner peripheral wall surface 65a. The end P5a of the inner peripheral wall surface 65a and the end P5b of the outer peripheral wall surface 65b are connected to the wall surface constituting the intake port 42a.

[0033] The straight channel 62 includes a first wall surface 62a connected in axial direction D1 to the end P1a of the inner circumferential wall surface 61a and the start P2a of the inner circumferential wall surface 63a, and a second wall surface 62b connected in axial direction D1 to the end P1b of the outer circumferential wall surface 61b and the start P2b of the outer circumferential wall surface 63b. In the cross-section shown in Figure 2, the first wall surface 62a and the second wall surface 62b are represented as parallel straight lines extending in axial direction D1. The first wall surface 62a may be the portion of the wall surface constituting the straight channel 62 that corresponds to the inner circumferential wall surface 61a and the inner circumferential wall surface 63a. The second wall surface 62b may be the portion of the wall surface constituting the straight channel 62 that corresponds to the outer circumferential wall surface 61b and the outer circumferential wall surface 63b. The second wall surface 62b may be the portion of the wall surface excluding the first wall surface 62a.

[0034] The straight channel 64 includes a first wall surface 64a connected vertically in D2 to the end P3a of the inner circumferential wall surface 63a and the start P4a of the inner circumferential wall surface 65a, and a second wall surface 64b connected vertically in D2 to the end P3b of the outer circumferential wall surface 63b and the start P4b of the outer circumferential wall surface 65b. In the cross-section shown in Figure 2, the first wall surface 64a and the second wall surface 64b are represented as parallel straight lines extending vertically in D2. The first wall surface 64a may be the portion of the wall surface constituting the straight channel 64 that corresponds to the inner circumferential wall surface 63a and the inner circumferential wall surface 65a. The second wall surface 64b may be the portion of the wall surface constituting the straight channel 64 that corresponds to the outer circumferential wall surface 63b and the outer circumferential wall surface 65b. The second wall surface 64b may be the portion of the wall surface excluding the first wall surface 64a.

[0035] The area of ​​each channel cross-section of the interstage channel 60 is, for example, constant. That is, the area of ​​the channel cross-section of the interstage channel 60 at any position along the center line CL is set to be the same as the area of ​​the channel cross-section of the interstage channel 60 at any other position along the center line CL. Therefore, the cross-sectional areas of the straight channel 62, the straight channel 64, the curved channel 61, the curved channel 63, and the curved channel 65 are all the same. The statement that the cross-sectional areas of each channel are all the same is not limited to the case where the cross-sectional areas of each channel are strictly the same, but each channel's cross-sectional area may include a certain range of tolerance. A certain range of tolerance means, for example, the error in the cross-sectional area of ​​each channel within the range in which the pressure loss occurring in the fluid R flowing through each channel is acceptable.

[0036] Figure 3 shows a magnified view of the vicinity of the curved channel 63 of the interstage channel 60. When the cross-sectional area of ​​the curved channel 63 is constant, the distance between the outer circumferential side wall 63b and the inner circumferential side wall 63a is a constant distance d at each position along the extension direction of the center line CL. In other words, the distance between the outer circumferential side wall 63b and the inner circumferential side wall 63a at any position along the center line CL is the same as (i.e., a constant distance d) the distance between the outer circumferential side wall 63b and the inner circumferential side wall 63a at any other position along the center line CL. The distance between the outer circumferential side wall 63b and the inner circumferential side wall 63a refers to the distance between the outer circumferential side wall 63b and the inner circumferential side wall 63a in the direction perpendicular to the center line CL in the cross-section shown in Figure 3. The distance between the first wall surface 62a and the second wall surface 62b of the straight channel 62, the distance between the first wall surface 64a and the second wall surface 64b of the straight channel 64, the distance between the outer circumferential wall surface 61b and the inner circumferential wall surface 61a of the curved channel 61, and the distance between the outer circumferential wall surface 65b and the inner circumferential wall surface 65a of the curved channel 65 may also be a constant distance d at each position along the extension direction of the center line CL.

[0037] The shapes of the cross-sections of each channel in the interstage channel 60 are, for example, identical in shape to one another. Figure 4(a) shows the cross-sectional shape of the curved channel 63 in a plane perpendicular to the center line CL. As shown in Figure 4(a), the cross-sectional shape of the curved channel 63 is not circular, but U-shaped. The inner circumferential side wall surface 63a constituting the curved channel 63 extends in a straight line in the cross-section shown in Figure 4(a). Therefore, the inner circumferential side wall surface 63a constitutes a plane that extends in the direction along the center line CL and in the direction perpendicular to the center line CL. The outer circumferential side wall surface 63b curves in the cross-section shown in Figure 4(a) so as to bulge outwards from the inner circumferential side wall surface 63a. Therefore, the outer circumferential side wall surface 63b constitutes a curved surface that extends along the direction along the center line CL and is curved in the direction perpendicular to the center line CL.

[0038] The outer peripheral wall surface 63b includes, in the cross-section shown in Figure 4(a), an arc-shaped curved portion P11 that curves so as to bulge outwards from the inner peripheral wall surface 63a, and a pair of straight portions P12 and P13 that connect the curved portion P11 and the inner peripheral wall surface 63a. The pair of straight portions P12 and P13 extend linearly from both ends of the inner peripheral wall surface 63a in a direction perpendicular to the inner peripheral wall surface 63a and are connected to both ends of the curved portion P11. The pair of straight portions P12 and P13 extend, for example, parallel to each other. The curved channels 61 and 65 also have the same cross-sectional shape as the curved channel 63.

[0039] Figure 4(b) shows the cross-sectional shape of the straight channel 62 in a plane perpendicular to the center line CL. As shown in Figure 4(b), the straight channel 62 has the same cross-sectional shape as, for example, the curved channel 63. The first wall surface 62a constituting the straight channel 62 extends in a straight line in the cross-section shown in Figure 4(b). Therefore, the first wall surface 62a, like the inner circumferential side wall surface 63a, constitutes a plane that extends in the direction along the center line CL and in the direction perpendicular to the center line CL. The second wall surface 62b, in the cross-section shown in Figure 4(b), is curved so as to bulge outwards from the first wall surface 62a. Therefore, the second wall surface 62b, like the outer circumferential side wall surface 63b, constitutes a curved surface that extends along the direction along the center line CL and is curved in the direction perpendicular to the center line CL.

[0040] The second wall surface 62b includes, in the cross-section shown in Figure 4(b), an arc-shaped curved section P21 that curves so as to bulge outwards from the first wall surface 62a, and a pair of straight sections P22 and P23 that connect the curved section P21 and the first wall surface 62a. The pair of straight sections P22 and P23 extend linearly from both ends of the first wall surface 62a in a direction perpendicular to the first wall surface 62a and are connected to both ends of the curved section P21. The pair of straight sections P22 and P23 extend, for example, parallel to each other. The straight channel 64 also has the same cross-sectional shape as the straight channel 62.

[0041] As described above, the interstage flow channel 60 having the above configuration is formed by a combination of the first housing 41, the interstage plate 43, the second housing 42, and the interstage housing 44. In other words, the wall surface constituting the interstage flow channel 60 is formed separately for the first housing 41, the interstage plate 43, the second housing 42, and the interstage housing 44. In the cross-section shown in Figure 2, boundary lines L1, L2, and L3 are shown indicating the boundaries between the first housing 41, the interstage plate 43, the second housing 42, and the interstage housing 44. Boundary line L1 indicates the boundary between the first housing 41 and the interstage plate 43. Boundary line L2 indicates the boundary between the interstage plate 43 and the second housing 42. Boundary line L3 indicates the boundary between the second housing 42 and the interstage housing 44.

[0042] Boundary line L1 extends vertically D2 through the curved channel 61 of the interstage channel 60. Boundary line L1 includes boundary line L11, boundary line L12, and boundary line L13. Boundary line L11 extends vertically D2 between the starting end Pa of the inner circumferential side wall surface 61a and the starting end Pb of the outer circumferential side wall surface 61b. For example, boundary line L11 extends vertically D2 so as to be tangent to the starting end Pa of the inner circumferential side wall surface 61a. Boundary line L11 passes through the scroll channel 41c. The lower end of boundary line L11 is located, for example, between the inner circumferential side wall surface 61a and the center line CL.

[0043] Boundary line L13 extends vertically in D2 below boundary line L11 and offset from boundary line L11 in the axial direction D1. Boundary line L13 extends vertically in D2, for example, so as to be tangent to or passing through the end P1b of the outer peripheral wall surface 61b. The upper end of boundary line L13 is, for example, at the same position as the lower end of boundary line L11 in the vertical direction D2. Boundary line L12 connects the lower end of boundary line L11 and the upper end of boundary line L13 in the axial direction D1. Boundary line L12 extends axially in D1 between the end P1a of the inner peripheral wall surface 61a and the end P1b of the outer peripheral wall surface 61b, more specifically, between the end P1a of the inner peripheral wall surface 61a and the center line CL. Boundary line L12 may extend axially in D1 so as to be tangent to the end P1a of the inner peripheral wall surface 61a. As a result of setting such a boundary line L1, the entire portion of the inner circumferential wall surface 61a from its starting point Pa to its ending point P1a is positioned on one side of the boundary line L1. The entire portion of the outer circumferential wall surface 61b from its starting point Pb to its ending point P1b is positioned on the other side of the boundary line L1.

[0044] Boundary line L2 is located between boundary line L1 and boundary line L3 and extends vertically D2 through the straight channel 62 of the interstage channel 60. Boundary line L2 includes boundary line L21 and boundary line L22. Boundary line L21 extends parallel to boundary line L11 and boundary line L13 with a gap between them. Boundary line L21 extends vertically D2 through the scroll channel 42c. Boundary line L22 extends axially D1 from the upper end of boundary line L21 and connects to boundary line L11 of boundary line L1.

[0045] Boundary line L3 extends vertically in D2 so as to pass through the curved channels 63 and 65 of the interstage channel 60. Boundary line L3 includes boundary line L31 (first boundary line), boundary line L32 (second boundary line), boundary line L33, boundary line L34, and boundary line L35. Boundary line L31 extends vertically in D2 between the end P3a of the inner circumferential wall surface 63a and the end P3b of the outer circumferential wall surface 63b. For example, boundary line L31 extends vertically in D2 so as to be tangent to the end P3a of the inner circumferential wall surface 63a. The lower end of boundary line L31 is located, for example, between the inner circumferential wall surface 63a and the center line CL. Boundary line L31 extends vertically in D2 between the starting end P4a of the inner circumferential wall surface 65a and the starting end P4b of the outer circumferential wall surface 65b. For example, boundary line L31 extends vertically in the direction D2 so as to be tangent to the starting end P4a of the inner circumferential wall surface 65a. The lower end of boundary line L31 is located, for example, between the inner circumferential wall surface 63a and the center line CL. The upper end of boundary line L31 is located, for example, between the inner circumferential wall surface 65a and the center line CL.

[0046] Boundary line L33 extends vertically in D2 below boundary line L31 and offset from boundary line L31 toward boundary line L2 in the axial direction D1. Boundary line L33 extends vertically in D2, for example, so as to be tangent to or passing through the starting end P2b of the outer peripheral wall surface 63b. The upper end of boundary line L33 is, for example, at the same position as the lower end of boundary line L31 in the vertical direction D2. Boundary line L32 connects the lower end of boundary line L31 and the upper end of boundary line L33 in the axial direction D1. Boundary line L32 extends axially in D1 between the starting end P2a of the inner peripheral wall surface 63a and the starting end P2b of the outer peripheral wall surface 63b, more specifically between the starting end P2a of the inner peripheral wall surface 63a and the center line CL. The boundary line L32 may extend in the axial direction D1, for example, so as to be tangent to the starting end P2a of the inner circumferential side wall surface 63a.

[0047] Boundary line L34 extends vertically in D2 at a position above boundary line L31 and offset from boundary line L31 axially D1 toward boundary line L2. Boundary line L34 extends vertically in D2, for example, so as to be tangent to or passing through the end P5b of the outer peripheral wall surface 65b. The lower end of boundary line L34 is, for example, at the same position as the upper end of boundary line L31 in vertical direction D2. Boundary line L35 connects the upper end of boundary line L31 and the lower end of boundary line L34 axially in D1. Boundary line L35 extends axially in D1 between the end P5a of the inner peripheral wall surface 65a and the end P5b of the outer peripheral wall surface 65b, more specifically, between the end P5a of the inner peripheral wall surface 65a and the center line CL. Boundary line L35 may extend axially in D1 so as to be tangent to the end P5a of the inner peripheral wall surface 65a.

[0048] As a result of setting such a boundary line L3, the entire portion of the inner circumferential wall surface 63a from its starting point P2a to its ending point P3a is positioned on one side of the boundary line L3. The entire portion of the outer circumferential wall surface 63b from its starting point P2b to its ending point P3b is positioned on the other side of the boundary line L3. The entire portion of the inner circumferential wall surface 65a from its starting point P4a to its ending point P5a is positioned on one side of the boundary line L3. The entire portion of the outer circumferential wall surface 65b from its starting point P4b to its ending point P5b is positioned on the other side of the boundary line L3.

[0049] Figure 5 shows the state in which the first housing 41, the interstage plate 43, the second housing 42, and the interstage housing 44 are separated from each other at each boundary line L1, L2, and L3. As shown in Figure 5, boundary line L1 passing through the curved channel 61 separates the inner circumferential wall surface 61a and the outer circumferential wall surface 61b of the curved channel 61. As a result, the outer circumferential wall surface 61b located on one side of boundary line L1 (i.e., the entire portion of the outer circumferential wall surface 61b from the starting point Pb to the ending point P1b) is formed in the first housing 41. The inner circumferential wall surface 61a located on the other side of boundary line L1 (i.e., the entire portion of the inner circumferential wall surface 61a from the starting point Pa to the ending point P1a) is formed in the interstage plate 43. In other words, the inner circumferential wall surface 61a and the outer circumferential wall surface 61b that constitute the wall surface of the curved channel 61 are formed separately in the interstage plate 43 and the first housing 41, respectively.

[0050] The first housing 41 includes dividing surfaces S11a, S12a, and S13a formed by division at boundary line L1. Dividing surface S11a is a plane formed by division at boundary line L11 and extends in the vertical direction D2 in the cross-section shown in Figure 5. Dividing surface S13a is a plane formed by division at boundary line L13 and extends in the vertical direction D2 in the cross-section shown in Figure 5. Dividing surface S13a is offset, for example, from dividing surface S11a towards the straight flow channel 62 side in the axial direction D1. Dividing surface S12a is a plane formed by division at boundary line L12 and extends in the axial direction D1 in the cross-section shown in Figure 5. Dividing surface S12a connects dividing surfaces S11a and S13a in the axial direction D1. Dividing surface S12a is formed, for example, perpendicular to dividing surfaces S11a and S13a.

[0051] The interstage plate 43 includes dividing surfaces S11b, S12b, and S13b formed by division at boundary line L1. Dividing surface S11b is a plane formed by division at boundary line L11 and extends in the vertical direction D2 in the cross-section shown in Figure 5. Dividing surface S11b extends parallel to dividing surface S11a. Dividing surface S13b is a plane formed by division at boundary line L13 and extends in the vertical direction D2 in the cross-section shown in Figure 5. Dividing surface S13b is offset, for example, from dividing surface S11b towards the straight channel 62 in the axial direction D1. Dividing surface S12b is a plane formed by division at boundary line L12 and extends in the axial direction D1 in the cross-section shown in Figure 5. Dividing surface S12b connects dividing surface S11b and dividing surface S13b in the axial direction D1. The dividing surface S12b is formed perpendicular to, for example, the dividing surfaces S11b and S13b.

[0052] The boundary line L3, which passes through the curved channel 63 and the curved channel 65, separates the inner circumferential side wall surface 63a and the outer circumferential side wall surface 63b of the curved channel 63, and also separates the inner circumferential side wall surface 65a and the outer circumferential side wall surface 65b of the curved channel 65. As a result, the inner circumferential side wall surface 63a (i.e., the entire portion from the starting end P2a to the ending end P3a) and the inner circumferential side wall surface 65a (i.e., the entire portion from the starting end P4a to the ending end P5a) ​​located on one side of the boundary line L3 are formed in the second housing 42. The outer peripheral wall surface 63b (i.e., the entire portion of the outer peripheral wall surface 63b from its starting point P2b to its ending point P3b) and the outer peripheral wall surface 65b (i.e., the entire portion of the outer peripheral wall surface 65b from its starting point P4b to its ending point P5b) located on the other side of the boundary line L3 are formed in the inter-stage plate 43. In other words, the inner peripheral wall surface 63a and the outer peripheral wall surface 63b that constitute the wall surface of the curved channel 63 are formed separately in the second housing 42 and the inter-stage plate 43, respectively.

[0053] The second housing 42 includes dividing surfaces S31a, S32a, S33a, S34a, and S35a formed by division at boundary line L3. Dividing surface S31a is a plane formed by division at boundary line L31 and extends in the vertical direction D2 in the cross-section shown in Figure 5. Dividing surface S33a is a plane formed by division at boundary line L33 and extends in the vertical direction D2 in the cross-section shown in Figure 5. Dividing surface S34a is a plane formed by division at boundary line L34 and extends in the vertical direction D2 in the cross-section shown in Figure 5. Dividing surfaces S33a and S34a are offset, for example, from the dividing surface S31a toward the straight flow channel 62 side in the axial direction D1. Dividing surface S32a is a plane formed by division at boundary line L32 and extends in the axial direction D1 in the cross-section shown in Figure 5. The dividing surface S32a connects dividing surfaces S31a and S32a in the axial direction D1. The dividing surface S35a is a plane formed by the division at boundary line L35 and extends in the axial direction D1 in the cross-section shown in Figure 5. The dividing surface S35a connects dividing surfaces S31a and S34a in the axial direction D1. Dividing surfaces S32a and S35a are formed perpendicular to, for example, dividing surfaces S31a, S33a, and S34a.

[0054] The interstage housing 44 includes dividing surfaces S31b, S32b, S33b, S34b, and S35b formed by division at boundary line L3. Dividing surface S31b is a plane formed by division at boundary line L31 and extends in the vertical direction D2 in the cross-section shown in Figure 5. Dividing surface S33b is a plane formed by division at boundary line L33 and extends in the vertical direction D2 in the cross-section shown in Figure 5. Dividing surface S34b is a plane formed by division at boundary line L34 and extends in the vertical direction D2 in the cross-section shown in Figure 5. Dividing surfaces S33b and S34b are offset, for example, towards the straight flow channel 62 side in the axial direction D1 relative to dividing surface S31b. Dividing surface S32b is a plane formed by division at boundary line L32 and extends in the axial direction D1 in the cross-section shown in Figure 5. The dividing surface S32b connects dividing surfaces S31b and S32b in the axial direction D1. The dividing surface S35b is a plane formed by the division at boundary line L35 and extends in the axial direction D1 in the cross-section shown in Figure 5. The dividing surface S35b connects dividing surfaces S31b and S34b in the axial direction D1. Dividing surfaces S32b and S35b are formed perpendicular to, for example, dividing surfaces S31b, S33b, and S34b.

[0055] As described above, the inner and outer circumferential sidewalls constituting the curved passage are formed on separate parts. As a result, the shapes of each component constituting the housing of the compression unit 30 (i.e., the first housing 41, the interstage plate 43, the second housing 42, and the interstage housing 44) are such that they can be molded with the axial direction D1 as the mold-cutting direction. Here, "mold" refers to, for example, a casting mold. An annular sealing member such as an O-ring may be installed at the connection portion of the interstage passage 60 in each component. In this case, leakage of the fluid R flowing through the interstage passage 60 is suppressed.

[0056] <Effects and Effects> The effects and advantages of the compressor 1 according to this embodiment, as described above, will be explained along with the problems of the comparative example.

[0057] In the compressor compression unit 130 shown in Figure 6, the first housing 141, which houses the first impeller 131, and the second housing 142, which houses the second impeller 132, are connected by piping 170. Inside the piping 170, an interstage passage 160 is formed to introduce fluid R from the first impeller 131 to the second impeller 132. An interstage plate 143 is positioned between the first housing 141 and the second housing 142. In this configuration, where the piping 170 is connected to the first housing 141 and the second housing 142, the cost of the piping 170 itself is in addition to the cost of the assembly of the piping 170, which tends to increase mass production costs. Therefore, it is difficult to improve the productivity of the compressor with the compression unit 130.

[0058] Therefore, it is conceivable to form such interstage passages in the housing of the compression unit. This allows for the formation of interstage passages without the use of piping, thereby reducing mass production costs. Furthermore, if the housing can be formed by die-casting, which has low manufacturing costs, mass production costs can be reduced even further. However, in order to form the housing by die-casting, the housing must be in a shape that can be molded out. Considering the fluid flow path through the interstage passage connecting the low-pressure compression stage and the high-pressure compression stage, there are one or more bends in the passage. Such bends can be a factor that hinders the molding of the housing.

[0059] For example, Figure 7(a) shows a configuration in which an interstage flow channel 160 having a curved flow channel 163 is formed within the housing of a compression unit. When such a curved flow channel 163 exists, it is conceivable to divide the housing into two parts (for example, a second housing 242 and an interstage housing 244) at a position passing through the curved flow channel 163 in order to make the housing a shape that can be molded. For example, if the boundary line L103 indicating the boundary between the second housing 242 and the interstage housing 244 is set to extend linearly in the vertical direction D2 between the end P103a of the inner circumferential side wall surface 163a and the end P103b of the outer circumferential side wall surface 163b of the curved flow channel 163, the boundary line L103 intersects with the outer circumferential side wall surface 163b, dividing the outer circumferential side wall surface 163b into part P111 and part P112. As a result, the portion P111 of the outer peripheral wall surface 163b and the inner peripheral wall surface 163a are formed in the same second housing 242. In this case, since the overhang portion B1 is formed in portion P111, it is not possible to cut out the second housing 242 with the axial direction D1 as the cutting direction.

[0060] On the other hand, as shown in Figure 7(b), if the boundary line L203 indicating the boundary between the second housing 342 and the interstage housing 344 extends linearly in the vertical direction D2 so as to pass through the starting end P102a of the inner circumferential side wall surface 163a and the starting end P102b of the outer circumferential side wall surface 163b of the curved flow channel 163, then the inner circumferential side wall surface 163a and the outer circumferential side wall surface 163b are formed in the same interstage housing 344. In this case, since an overhang portion B2 is formed on the inner circumferential side wall surface 163a, it is not possible to die-cast the interstage housing 344 with the axial direction D1 as the die-casting direction. Therefore, with boundary lines L103 and L203 as shown in Figures 7(a) and 7(b), each component cannot be formed by die-casting.

[0061] In contrast, as shown in Figure 8(a), it is conceivable to set the boundary line L303, which indicates the boundary between the second housing 442 and the interstage housing 444, at the same position as the boundary line L103, and to ensure that the outer peripheral wall surface 263b of the curved flow path 263 is not divided by the boundary line L303. In other words, it is conceivable to adjust the shape of the outer peripheral wall surface 263b (degree of bending, etc.) so that the outer peripheral wall surface 263b does not extend beyond the boundary line L303. Specifically, it is conceivable to adjust the position of the starting end P202b of the outer peripheral wall surface 263b so that it is on the same side as the ending end P203b relative to the boundary line L303. In this case, the starting end P202b and ending end P203b of the outer peripheral wall surface 263b are located on one side of the boundary line L303, and the starting end P202a and ending end P203a of the inner peripheral wall surface 263a are located on the other side of the boundary line L303. In other words, the inner circumferential wall surface 263a and the outer circumferential wall surface 263b are formed separately as the second housing 442 and the inter-stage housing 444.

[0062] Consequently, unlike the case where the inner circumferential side wall surface 263a and the outer circumferential side wall surface 263b are formed in a single housing, no overhang is formed in either the second housing 442 or the inter-stage housing 444, so both the second housing 442 and the inter-stage housing 444 are shaped to be molded. Therefore, in the example shown in Figure 8(a), the second housing 442 and the inter-stage housing 444 can be formed by die-casting. However, in this example, due to the adjustment of the shape of the outer circumferential side wall surface 263b, the distance between the outer circumferential side wall surface 263b and the inner circumferential side wall surface 263a is not a constant distance d, but a distance d1 that is greater than distance d. In this case, a change occurs in the cross-sectional area of ​​the curved channel 263. Such a change in the cross-sectional area of ​​the curved channel 263 can affect the flow of the fluid R flowing through the curved channel 263.

[0063] Therefore, as shown in Figure 8(b), it is conceivable to shift the boundary line L3, which indicates the boundary between the second housing 42 and the interstage housing 44, in the axial direction D1. Figure 8(b) shows the same configuration as the compressor 1 according to the above-described embodiment. As described above, boundary line L31 of boundary line L3 extends vertically in the direction D2 between the end P3a of the inner circumferential wall surface 63a and the end P3a of the outer circumferential wall surface 63b. Boundary line L33 extends axially in the direction D1 between the starting end P2a of the inner circumferential wall surface 63a and the starting end P2a of the outer circumferential wall surface 63b and is connected to boundary line L31. Boundary line L32 extends downward from boundary line L33. When the second housing 42 and the interstage housing 44 are separated by such boundary line L3, the inner circumferential wall surface 63a and the outer circumferential wall surface 63b are formed separately for the second housing 42 and the interstage housing 44, similar to the example shown in Figure 8(a). In this case, since no overhang is formed on either the second housing 42 or the interstage housing 44, both the second housing 42 and the interstage housing 44 become die-castable. As a result, each component of the compression unit 30 can be molded using die casting, which has a low manufacturing cost, thus improving productivity. This allows for the reduction of mass production costs.

[0064] Furthermore, as shown in Figure 8(b), by setting a boundary line L3 that is shifted in the axial direction D1, it is not necessary to make adjustments such as changing the shape of the inner circumferential side wall surface 63a or the outer circumferential side wall surface 63b to match the boundary line L3. Therefore, the inner circumferential side wall surface 63a and the outer circumferential side wall surface 63b can be formed in separate housings, regardless of their respective shapes. As a result, it is possible to avoid situations in which changes occur in the cross-section of each flow path of the curved flow path 63 due to changes in the shape of the inner circumferential side wall surface 63a and the outer circumferential side wall surface 63b. In other words, the distance between the inner circumferential side wall surface 63a and the outer circumferential side wall surface 63b can be kept at a constant distance d. This suppresses pressure loss in the fluid R flowing through the curved flow path 63 and suppresses a decrease in the performance of the compressor 1.

[0065] In the embodiment described above, in a cross-section perpendicular to the center line CL of the curved flow path 63, the inner circumferential side wall surface 63a extends in a straight line, while the outer circumferential side wall surface 63b curves so as to bulge outwards from the inner circumferential side wall surface 63a. With this configuration, die casting of each component can be easily performed by setting the direction from the outer circumferential side wall surface 63b toward the inner circumferential side wall surface 63a as the demolding direction.

[0066] In the embodiment described above, the interstage housing 44 is connected in series to the first housing 41 via the second housing 42, forming the interstage flow path 60. In this configuration, the interstage flow path 60 can be easily formed by the simple operation of connecting the interstage housing 44, the second housing 42, and the first housing 41 in series.

[0067] In the embodiment described above, the interstage plate 43 is sandwiched between the first housing 41 and the second housing 42, forming the interstage flow path 60. In this configuration, the interstage flow path 60 can be easily formed using the interstage plate 43.

[0068] In the embodiment described above, the straight channel 62 includes a first wall surface 62a and a second wall surface 62b that extend linearly and parallel to each other. The first wall surface 62a and the second wall surface 62b are formed in the second housing 42. In this case, the second housing 42 can be molded using the axial direction D1 in which the straight channel 62 extends as the mold-cutting direction. Therefore, even in an interstage channel 60 having a curved channel 63 and a straight channel 62, it is possible to mold each component.

[0069] In the embodiments described above, the configuration of the curved channel 63 of the interstage channel 60 was mainly explained, but the other curved channels 61 and 65 can be explained similarly. The "curved channel" in this disclosure may be interpreted as any of the curved channels 61, 63, and 65. In the embodiments described above, the case in which the "straight channel" in this disclosure is applied to the straight channel 62 was explained, but the "straight channel" in this disclosure may also be applied to other straight channels 64. The "interstage channel" in this disclosure only needs to have at least one curved channel, and does not need to have a straight channel.

[0070] Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment.

[0071] <Example 1> In the example shown in Figure 9, the straight channel 64A connecting the curved channel 63A and the curved channel 65A extends in a direction inclined from the vertical direction D2. For example, the straight channel 64A extends in a direction that forms an acute angle with respect to the straight channel 62. Accordingly, the curved channel 65A is positioned offset from the curved channel 63A towards the intake port 42a in the axial direction D1. The boundary line L3A indicating the boundary between the interstage housing 44A and the second housing 42A has a boundary line L31A (second boundary line) instead of boundary line L31. Boundary line L31A extends upward from boundary line L33 (first boundary line), curves following the inner circumferential wall surface 63a so as to be in contact with the end P3a of the inner circumferential wall surface 63a, and then extends linearly along the first wall surface 64a to connect to boundary line L35.

[0072] Even when such an interstage flow channel 60A is formed, the boundary line L3A separates the second housing 42A from the interstage housing 44A, so that the inner circumferential wall surface 63a of the curved flow channel 63A, the first wall surface 64a of the straight flow channel 64A, and the inner circumferential wall surface 65a of the curved flow channel 65A are formed in the second housing 42A. Furthermore, the outer circumferential wall surface 63b of the curved flow channel 63A, the second wall surface 64b of the straight flow channel 64A, and the outer circumferential wall surface 65b of the curved flow channel 65A are formed in the interstage housing 44A. By forming the wall surface of each flow channel into two parts (i.e., the second housing 42A and the interstage housing 44A) in this way, each part can be made into a shape that can be cut out. Furthermore, similar to the embodiment described above, by shifting the boundary line L3A in the axial direction D1, each part can be made into a shape that can be cut out regardless of the shape of the wall surface of each flow channel. This suppresses the occurrence of cross-sectional area changes in the interstage flow path 60A, and also suppresses the occurrence of pressure loss in the fluid R flowing through the interstage flow path 60A. Therefore, even in the configuration shown in Figure 9, the same effects as in the embodiment described above can be obtained.

[0073] <Modification 2> In the example shown in Figure 10, the curved passage 63B is directly connected to the intake port 42a. As a result, the starting point P2a and ending point P3a of the inner circumferential wall surface 63a, and the starting point P2b and ending point P3b of the outer circumferential wall surface 63b are aligned in the same position in the vertical direction D2. The boundary line L3B indicating the boundary between the interstage housing 44B and the second housing 42B has a boundary line L31B instead of boundary line L31. Boundary line L31B extends vertically in the vertical direction D2 between the inner circumferential wall surface 63a and the outer circumferential wall surface 63b. The lower end of boundary line L31B is in the same position as the starting point P2a of the inner circumferential wall surface 63a in the vertical direction D2 and is connected to boundary line L33 (first boundary line). The upper end of boundary line L31B is in the same position as the ending point P3a of the inner circumferential wall surface 63a in the vertical direction D2 and is connected to boundary line L35 (second boundary line).

[0074] Even when such an interstage flow path 60B is formed, the boundary line L3B separates the second housing 42B and the interstage housing 44B, so that the inner circumferential side wall surface 63a of the curved flow path 63B is formed in the second housing 42B, and the outer circumferential side wall surface 63b of the curved flow path 63B is formed in the interstage housing 44B. By forming the wall surface of each flow path in this way, divided into two parts (i.e., the second housing 42B and the interstage housing 44B), each part can be made into a shape that can be molded. Furthermore, similar to the embodiment described above, by shifting the boundary line L3B in the axial direction D1, each part can be made into a shape that can be molded regardless of the shape of the wall surface of each flow path, thereby suppressing the occurrence of a change in cross-sectional area in the interstage flow path 60B and suppressing the occurrence of a pressure loss in the fluid R flowing through the interstage flow path 60B. Therefore, even in the configuration shown in Figure 10, the same effects as in the embodiment described above can be obtained.

[0075] This disclosure is not limited to the embodiments and modifications described above, and various other modifications are possible. For example, the embodiments and modifications described above may be combined with each other depending on the required purpose and effect. In the embodiments described above, a two-stage compressor was used as an example. However, the number of stages of the compressor is not limited to two, and may be three or more. In the embodiments described above, an example was described in which the interstage flow path 60 is composed of four parts: a first housing 41, a second housing 42, an interstage plate 43, and an interstage housing 44. However, it is not necessarily required to be formed by four parts. For example, the interstage plate does not need to extend downward until it reaches the interstage flow path, and the second housing may be directly connected to the first housing. In this case, the interstage flow path is formed by three parts: the first housing, the second housing, and the interstage housing. In the embodiments described above, piping for connecting the first housing and the second housing may be provided separately. In this case, the piping may be bypass-connected to the interstage flow path.

[0076] [Note] This disclosure includes the following components:

[0077] The compressor of the present disclosure is [1] "a compressor for further compressing a fluid compressed by a first impeller with a second impeller, comprising: an impeller housing having a first housing for housing the first impeller and a second housing for housing the second impeller; and an interstage component connected to the impeller housing and, together with the impeller housing, forming an interstage passage for introducing the fluid from the first impeller to the second impeller, wherein the interstage passage has at least one curved passage, the curved passage includes an inner circumferential side wall surface that curves on the inner side in a cross-section passing through the centerline of the curved passage, and an outer circumferential side wall surface that curves on the outer side in the cross-section, one of the inner circumferential side wall surface and the outer circumferential side wall surface being formed in the impeller housing, and the other of the inner circumferential side wall surface and the outer circumferential side wall surface being formed in the interstage component."

[0078] The compressor of the present disclosure is [2] "the compressor according to [1] above, wherein the boundary line indicating the boundary between the impeller housing and the interstage component in the cross section has a first boundary line and a second boundary line between the inner circumferential side wall surface and the outer circumferential side wall surface, the first boundary line extends so as to intersect a straight line connecting the starting end of the inner circumferential side wall surface and the starting end of the outer circumferential side wall surface, the second boundary line extends so as to intersect a straight line connecting the end of the inner circumferential side wall surface and the end of the outer circumferential side wall surface, and is directly or indirectly connected to the first boundary line between the inner circumferential side wall surface and the outer circumferential side wall surface."

[0079] The compressor of the present disclosure is [3] "the compressor according to [1] or [2] above, wherein the distance between the inner circumferential side wall surface and the outer circumferential side wall surface in a direction perpendicular to the center line is constant at each position along the center line."

[0080] The compressor of the present disclosure is [4] "the compressor according to any one of [1] to [3] above, wherein in a cross section perpendicular to the center line of the curved flow path, the inner circumferential side wall surface extends in a straight line, and the outer circumferential side wall surface is curved so as to bulge out from the inner circumferential side wall surface toward the opposite side from the inner circumferential side wall surface."

[0081] The compressor of the present disclosure is [5] "the compressor according to any one of [1] to [4] above, wherein the interstage component is an interstage housing connected in series to the first housing via the second housing, the inner circumferential side wall surface is formed on the second housing, and the outer circumferential side wall surface is formed on the interstage component."

[0082] The compressor of the present disclosure is [6] "the compressor according to any one of [1] to [4] above, wherein the interstage component is an interstage plate sandwiched between the first housing and the second housing, the inner circumferential side wall surface is formed on the interstage component, and the outer circumferential side wall surface is formed on the first housing."

[0083] The compressor of the present disclosure is [7] "the compressor according to any one of [1] to [6] above, wherein the interstage passage further comprises a straight passage extending linearly from the curved passage, the straight passage comprising a first wall surface connected to the inner circumferential wall surface and a second wall surface connected to the outer circumferential wall surface, the first wall surface and the second wall surface extending parallel to each other in the cross-section passing through the center line, and formed in the impeller housing." [Explanation of Symbols]

[0084] 1. Compressor 31 First Impeller 32. Second impeller 33 Impeller Housing 41 Housing 1 42, 42A, 42B Second Housing 43 Inter-stage plates (inter-stage components) 44, 44A, 44B Interstage housing (interstage component) 60,60A,60B Interstage flow path 61, 63, 63A, 63B, 65, 65A curved channel 61a, 63a, 65a Inner wall surface 61b, 63b, 65b Outer perimeter side walls 62, 64, 64A Straight channel 62a, 64a First wall 62b, 64b Second wall CL center line d,d1 distance L1,L2,L3,L3A,L3B,L11,L12,L13,L21,L22,L31A,L31B,L33,L34,L35 Boundary line P1a,P1b,P3a,P3b,P5a,P5b Termination Pa,Pb,P2a,P2b,P4a,P4b Starting end R fluid

Claims

1. A compressor that further compresses a fluid compressed by a first impeller using a second impeller, An impeller housing having a first housing for housing the first impeller and a second housing for housing the second impeller, The system includes an interstage component connected to the impeller housing, which together with the impeller housing forms an interstage passage for introducing the fluid from the first impeller to the second impeller, The interstage channel has at least one curved channel, The curved channel includes an inner circumferential wall surface that curves on the inner side in a cross-section passing through the center line of the curved channel, and an outer circumferential wall surface that curves on the outer side in the cross-section. One of the inner circumferential side wall surface and the outer circumferential side wall surface is formed in the impeller housing, The other of the inner circumferential side wall surface and the outer circumferential side wall surface is formed in the interstage component, A compressor in which the distance between the inner circumferential side wall surface and the outer circumferential side wall surface in a direction perpendicular to the center line is constant at each position along the center line.

2. In the cross-section, the boundary line indicating the boundary between the impeller housing and the interstage component has a first boundary line and a second boundary line between the inner circumferential side wall surface and the outer circumferential side wall surface. The first boundary line extends so as to intersect the straight line connecting the starting end of the inner circumferential side wall surface and the starting end of the outer circumferential side wall surface. The compressor according to claim 1, wherein the second boundary line extends so as to intersect a straight line connecting the end of the inner circumferential side wall surface and the end of the outer circumferential side wall surface, and is directly or indirectly connected to the first boundary line between the inner circumferential side wall surface and the outer circumferential side wall surface.

3. The compressor according to claim 1 or 2, wherein, in a cross section perpendicular to the center line of the curved flow path, the inner circumferential side wall surface extends in a straight line, and the outer circumferential side wall surface is curved so as to bulge outwards from the inner circumferential side wall surface on the opposite side.

4. The interstage component is an interstage housing connected in series to the first housing via the second housing, The inner circumferential side wall surface is formed in the second housing, The compressor according to any one of claims 1 to 3, wherein the outer peripheral wall surface is formed on the interstage component.

5. The interstage component is an interstage plate sandwiched between the first housing and the second housing, The inner circumferential side wall surface is formed in the interstage component, The compressor according to any one of claims 1 to 3, wherein the outer peripheral wall surface is formed in the first housing.

6. The interstage channel further comprises a straight channel extending linearly from the curved channel, The straight channel includes a first wall surface connected to the inner circumferential wall surface and a second wall surface connected to the outer circumferential wall surface. The compressor according to any one of claims 1 to 5, wherein the first wall surface and the second wall surface extend parallel to each other in the cross-section passing through the center line and are formed in the impeller housing.

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