Multistage pump

Abstract

To provide a multistage pump capable of preventing defective assembly while actualizing easy assembly.SOLUTION: A multistage pump 1 including a main shaft 12, a plurality of impellers 42, 62 provided on the main shaft 12, a plurality of casings 41, 61, 34 storing the impellers 42, 62 and layered on one another, protruded parts 52c, 72c, 82c provided on the plurality of casings 41, 61, 34, and recessed parts 52d, 72d, 82d provided in the plurality of casings 41, 61, 34 for engaging with the protruded parts 52c, 72c, 82c around the axis. The protruded parts 52c, 72c, 82c and the recessed parts 52d, 72d, 82d provided on and in any neighboring casings 41, 61, 34, out of the plurality of casings 41, 61, 34, are different in at least one of the peripheral width, the axial length, the radial width, the outer shape, and the peripheral position and the number.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a multi-stage pump having multiple impellers and casings. [Background technology]

[0002] A technology using a multi-stage pump is known as a water supply device for supplying water to skyscrapers, tower apartments, etc. (see, for example, Patent Document 1). The multi-stage pump has a pump section with multiple stages. The pump section is formed by an impeller and a pump casing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-74359 A Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned multi-stage pump has multiple pump stages, but if the casings of these multiple pump stages include different or similar shapes, mistakes in the assembly order or direction may occur, resulting in an assembly that differs from the design intent and may result in assembly defects. For this reason, there is a demand for a multi-stage pump that can be easily assembled in order to prevent assembly defects.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a multi-stage pump that can be easily assembled and that can prevent assembly defects. [Means for solving the problem]

[0006] In one aspect of the invention, a multi-stage pump comprises a main shaft, a plurality of impellers mounted on the main shaft, a plurality of casings that house the impellers and are stacked on one another, convex portions provided on the plurality of casings, and concave portions provided on the plurality of casings that engage with the convex portions of adjacent casings around the axis, and the convex portions and the concave portions provided on any adjacent casings among the plurality of casings differ in at least one of circumferential width, axial length, radial width, external shape, circumferential position, and number. Effect of the Invention

[0007] According to the present invention, it is possible to provide a multi-stage pump that can be easily assembled and that can prevent assembly defects. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing, in partial cross section, the configuration of a multi-stage pump according to an embodiment of the present invention; [Diagram 2] 2 is a perspective view showing the configurations of a first pump casing and a second pump casing used in the multi-stage pump. FIG. [Diagram 3] 4 is a plan view showing the configuration of the primary side in the fluid flow direction of a first pump casing and a second pump casing used in the multi-stage pump. FIG. [Figure 4] 4 is a plan view showing the configuration of the secondary side in the fluid flow direction of a first pump casing and a second pump casing used in the multi-stage pump. FIG. [Diagram 5] 2 is a perspective view showing the configuration of a first pump casing and a second pump casing of the first embodiment, partially in cross section; FIG. [Figure 6] 2 is a cross-sectional view showing the configuration of a first impeller and a second impeller used in the multi-stage pump. FIG. [Figure 7] FIG. 2 is a perspective view showing the configuration of a central casing used in the multi-stage pump. [Figure 8] FIG. 2 is a perspective view showing the configuration of the central casing in partial cross section. [Figure 9]FIG. 4 is an explanatory diagram showing an example of the relationship between convex portions and concave portions used in each casing of the multi-stage pump. [Figure 10] FIG. 4 is an explanatory diagram showing an example of the relationship between convex portions and concave portions used in each casing of the multi-stage pump. [Figure 11] FIG. 11 is a side view, partially in cross section, showing the configuration of a multi-stage pump according to another embodiment. [Figure 12] FIG. 2 is a partial cross-sectional view illustrating the configuration of a pump casing of the multi-stage pump. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the configuration of a multi-stage pump 1 according to a first embodiment of the present invention will be described with reference to FIGS.

[0010] FIG. 1 is a cross-sectional view showing a configuration of a multi-stage pump 1 according to an embodiment of the present invention, partially seen from the side. FIG. 2 is a perspective view showing the configuration of a first pump casing 41 and a second pump casing 61 used in the multi-stage pump 1, and FIG. 3 and FIG. 4 are plan views showing the configuration of the primary side and the secondary side in the fluid flow direction of the first pump casing 41 and the second pump casing 61 used in the multi-stage pump 1, respectively. FIG. 5 is a perspective view showing the configuration of the first pump casing 41 and the second pump casing 61, partially in cross section. FIG. 6 is a cross-sectional view showing the configuration of the first impeller 42 and the second impeller 62 used in the multi-stage pump 1. FIG. 7 is a perspective view showing the configuration of a central casing 34 used in the multi-stage pump 1, and FIG. 8 is a perspective view showing the configuration of the central casing 34, partially in cross section. FIG. 9 and FIG. 10 are explanatory views showing an example of the relationship between the convex parts 52c, 72c, 82c and the concave parts 52d, 72d, 82d provided in each casing 41, 34, 61, respectively.

[0011] 1, the multi-stage pump 1 includes a motor 11, a main shaft 12, and a pump 13. For example, the multi-stage pump 1 is a vertical multi-stage pump in which the main shaft 12 extends in the direction of gravity.

[0012] 1, the motor 11 includes a motor casing 11a, a stator provided in the motor casing 11a, and a rotor rotated by the stator. The motor 11 also includes a motor main shaft 21.

[0013] The motor main shaft 21 is fixed to the rotor. The motor main shaft 21 rotates with the rotation of the rotor. The motor main shaft 21 is supported by a bearing in the motor casing.

[0014] 1, the main shaft 12 is configured to be rotatable by the motor 11. The main shaft 12 extends in the direction of gravity so as to be capable of fixing a plurality of impellers provided in the pump 13. The main shaft 12 is configured, for example, by a motor main shaft 21, a pump main shaft 22, and a shaft coupling 23.

[0015] The pump main shaft 22 is disposed in the pump 13. The pump main shaft 22 is formed so that a plurality of impellers 42, 62 provided in the pump 13 can be fixed to the pump main shaft 22. The pump main shaft 22 is one of the components of the pump 13.

[0016] The shaft coupling 23 connects the motor main shaft 21 and the pump main shaft 22 so that the pump main shaft 22 can rotate in conjunction with the rotation of the motor main shaft 21 .

[0017] As shown in FIG. 1, the pump 13 has a plurality of pump sections each having an impeller and a casing. Specifically, the pump 13 includes a pump main shaft 22, a flow passage cover 31 that forms an intake port 31a and an exhaust port 31b, a first pump group 32A that forms an upward flow, a second pump group 33A that is disposed above the first pump group 32A and forms a downward flow, a central casing 34 provided between the first pump group 32A and the second pump group 33A, and a casing cover 35. In addition, the pump 13 includes a mechanical seal 22a between the main shaft 12 and a casing cover 35 of the pump 13, which will be described later, and which allows a rotating ring fixed to the main shaft 12 and a fixed ring fixed to the casing cover 35 to rotate and slide, and seals a gap between the main shaft 12 and the mechanical seal 22a. As shown in FIG. 1, the intake port 31a of the flow passage cover 31 forms a flow passage to the first pump section 32 at the lowest stage. The discharge port 31b of the flow passage cover 31 forms a flow passage that is continuous with a first casing flow passage 32a (to be described later) of the first pump group 32A.

[0018] In addition, the first pump group 32A and the second pump group 33A have the impellers 42, 62 arranged facing in opposite directions to each other, so that the water pumping directions are set in opposite directions to each other in the axial direction. That is, the first pump group 32A has an upward water flow direction, and the second pump group 33A has a downward water flow direction.

[0019] The first pump group 32A is configured by stacking a plurality of first pump sections 32. The first pump sections 32 pump water sucked from below upward. The first pump section 32 includes a first pump casing 41 and a first impeller 42 fixed to the pump main shaft 22 and housed in the first pump casing 41.

[0020] 2 to 5, the first pump casing 41 includes an inner cylinder portion (first inner cylinder portion) 51, an outer cylinder portion (first outer cylinder portion) 52 covering the inner cylinder portion 51, and a plurality of ribs (first ribs) 53 integrally connecting the inner cylinder portion 51 and the outer cylinder portion 52. The first pump casing 41 has a plurality of openings 54 formed by a part of the outer circumferential surface of the inner cylinder portion 51, a part of the inner circumferential surface of the outer cylinder portion 52, and circumferentially opposing surfaces of two adjacent ribs 53. The multiple openings 54 are provided at equal intervals.

[0021] As shown in Figures 3 and 5, the first pump casing 41 has a storage section 41a that stores the first impeller 42 therein, a return flow path 41b formed from the outer periphery of the first pump casing 41 toward the center of the storage section 41a, and a guide vane 41c arranged in the storage section 41a of the first pump casing 41 connected to the primary side.

[0022] The return flow passage 41b has a plurality of return vanes 41d that guide water to the suction port of the secondary-side first pump casing 41. The return flow passage 41b forms a water flow that is continuous with the storage section 41a of the secondary-side first pump casing 41 or the storage section 81a of the central casing 34.

[0023] Further, the first pump casing 41 is formed so as to be connectable to the first pump casings 41, the central casing 34, and the flow path cover 31 adjacent thereto in the vertical direction.

[0024] For example, as shown in Fig. 2 to Fig. 5, the outer cylinder portion 52 of the first pump casing 41 has an engaging portion (first engaging portion) 52a at an upper end or a lower end, and an engaged portion (first engaged portion) 52b that engages with the engaging portion 52a at an upper end or a lower end. Also, as shown in Fig. 2 to Fig. 5, the outer cylinder portion 52 of the first pump casing 41 includes a convex portion 52c and a concave portion 52d formed at a predetermined position in the circumferential direction, for example. Here, the predetermined position is a position where the convex portion 52c and the concave portion 52d engage with each other and the ribs 53 of the adjacent first pump casings 41 face each other in the axial direction when the adjacent first pump casings 41 are assembled together, in other words, a position where the ribs 53 are at the same position in the circumferential direction.

[0025] The engaging portion 52a and the engaged portion 52b are formed so that one can be inserted into the other. For example, the outer diameter of the engaging portion 52a is formed to be the same as the inner diameter of the engaged portion 52b or to be slightly smaller than the inner diameter of the engaged portion 52b, and the engaging portion 52a is inserted into the engaged portion 52b.

[0026] The protrusion 52c engages with a recess 52d provided in the outer tubular portion 52 of the adjacent first pump casing 41, and restricts circumferential movement of the first pump casing 41. For example, the protrusion 52c is provided on the outer circumferential surface of the outer tubular portion 52. For example, the protrusion 52c is a columnar protrusion formed integrally with the outer circumferential surface of the outer tubular portion 52.

[0027] The recess 52d is provided on the outer circumferential surface of the outer tube portion 52. For example, the recess 52d is a columnar depression provided in the engaged portion 52b, specifically, a notch provided across the outer circumferential surface and the inner circumferential surface of the engaged portion 52b.

[0028] Such a convex portion 52c and concave portion 52d may be provided in one or more.

[0029] Such a plurality of first pump casings 41 are engaged in the axial direction at the engaging portions 52a and the engaged portions 52b by aligning the positions of the convex portions 52c and the concave portions 52d of the adjacent outer cylinder portions 52 in the circumferential direction and inserting the engaging portions 52a into the engaged portions 52b, and are engaged in the circumferential direction at the convex portions 52c and the concave portions 52d. In this way, the plurality of first pump casings 41 are connected at predetermined positions in the axial and circumferential directions.

[0030] The first pump casing 41 also has an opening separated from the first impeller 42 by a predetermined gap and an opening in which the pump main shaft 22 is disposed, and a liner ring 41e is provided on the inner periphery of the opening facing the first impeller 42. In addition, a submerged bearing 41f is disposed in one of the openings of the multiple first pump casings 41.

[0031] The first impeller 42 is formed of, for example, stainless steel, resin, etc. As shown in Figures 1 and 6, the first impeller 42 has a discharge portion 42a provided on the outer periphery side of the first impeller 42 and a suction portion 42b provided on one main surface side of the first impeller 42. The first impeller 42 is housed in the first pump casing 41 with the suction portion 42b facing downward in the axial direction.

[0032] The first pump group 32A includes a plurality of first pump casings 41 and a central casing 34 stacked together to define a first casing flow passage 32a in which a plurality of openings 54 communicate with each other in the axial direction.

[0033] The second pump group 33A is configured by stacking a plurality of second pump sections 33. The second pump section 33 pumps water sucked from above downward. The second pump section 33 includes a second pump casing 61 and a second impeller 62 fixed to the pump main shaft 22 and housed in the second pump casing 61. Here, as shown in FIG. 2, the second pump casing 61 has the same configuration as the first pump casing 41. That is, the second pump section 33 has the second pump casing 61 and the second impeller 62 arranged in the opposite direction to the first pump casing 41 and the first impeller 42, compared to the first pump section 32, so that the water pumping direction is set in the opposite direction. Therefore, in the multi-stage first pump group 32A, the lowest stage is the primary side and the highest stage is the secondary side in the water flow direction, and in the multi-stage second pump group 33A, the highest stage is the primary side and the lowest stage is the secondary side in the water flow direction.

[0034] As shown in FIG. 2 to FIG. 5, the second pump casing 61 includes an inner cylinder portion (second inner cylinder portion) 71, an outer cylinder portion (second outer cylinder portion) 72 that covers the inner cylinder portion 71, and a plurality of ribs (second ribs) 73 that integrally connect the inner cylinder portion 71 and the outer cylinder portion 72. The second pump casing 61 has a plurality of openings 74 formed by a part of the outer peripheral surface of the inner cylinder portion 71, a part of the inner peripheral surface of the outer cylinder portion 72, and the surfaces of two adjacent ribs 73 that face each other in the circumferential direction. The plurality of openings 74 are provided at equal intervals. The second pump casing 61 has the same configuration as the first pump casing 41. Therefore, the same drawings will be used for the explanation. However, the second pump casing 61 is different from the first pump casing 41 in the orientation of the impeller (second impeller 62) that is accommodated therein, and therefore, even if the configuration is the same, the detailed shape and the positional relationship of each component are different.

[0035] As shown in Figures 2 to 5, the second pump casing 61 includes a storage section 61a for storing the second impeller 62 therein, a return flow path 61b formed from the outer periphery of the second pump casing 61 toward the center of the storage section 61a, and a guide vane 61c arranged in the storage section 61a of the second pump casing 61 connected to the primary side.

[0036] The return flow passage 61b has a plurality of return vanes 61d that guide water to the suction port of the secondary-side second pump casing 61. The return flow passage 61b forms a water flow that is continuous with the storage section 61a of the secondary-side second pump casing 61 or the storage section 81a of the central casing 34.

[0037] Further, the second pump casing 61 is formed so as to be connectable to the second pump casings 61 and the central casing 34 adjacent thereto in the vertical direction.

[0038] For example, as shown in Fig. 2 to Fig. 5, the outer cylinder portion 72 of the second pump casing 61 has an engaging portion (second engaging portion) 72a at the upper end or the lower end, and an engaged portion (second engaged portion) 72b that engages with the engaging portion 72a at the lower end or the upper end. Also, as shown in Fig. 2 to Fig. 5, the outer cylinder portion 72 of the second pump casing 61 includes a convex portion 72c and a concave portion 72d formed at a predetermined position in the circumferential direction, for example. Here, the predetermined position is a position where the convex portion 72c and the concave portion 72d engage with each other and the ribs 63 of the adjacent second pump casings 61 face each other in the axial direction when the adjacent second pump casings 61 are assembled together, in other words, a position where the ribs 63 are at the same position in the circumferential direction.

[0039] The engaging portion 72a and the engaged portion 72b are formed so that one can be inserted into the other. For example, the outer diameter of the engaging portion 72a is formed to be the same as the inner diameter of the engaged portion 72b or slightly smaller than the inner diameter of the engaged portion 72b, and the engaging portion 72a is inserted into the engaged portion 72b.

[0040] The protrusion 72c engages with a recess 72d provided in the outer tubular portion 72 of the adjacent second pump casing 61, and restricts circumferential movement of the second pump casing 61. For example, the protrusion 72c is provided on the outer circumferential surface of the outer tubular portion 72. For example, the protrusion 72c is a columnar protrusion formed integrally with the outer circumferential surface of the outer tubular portion 72.

[0041] The recess 72d is provided on the outer circumferential surface of the outer tube portion 72. For example, the recess 72d is a columnar depression provided in the engaged portion 72b, specifically, a notch provided across the outer circumferential surface and the inner circumferential surface of the engaged portion 72b.

[0042] Such a convex portion 72c and concave portion 72d may be provided in one or more.

[0043] Such a plurality of second pump casings 61 are engaged in the axial direction at the engaging portions 72a and the engaged portions 72b by aligning the positions of the convex portions 72c and the concave portions 72d of adjacent outer cylinder portions 72 in the circumferential direction and inserting the engaging portions 72a into the engaged portions 72b, and are engaged in the circumferential direction at the convex portions 72c and the concave portions 72d. In this way, the plurality of second pump casings 61 are connected at predetermined positions in the axial and circumferential directions.

[0044] In addition, the second pump casing 61 has an opening separated from the second impeller 62 by a predetermined gap, and an opening in which the pump main shaft 22 is disposed, and a liner ring 61e is provided on the inner peripheral edge of the opening facing the second impeller 62.

[0045] The second impeller 62 is formed of, for example, stainless steel or resin. As shown in Fig. 6, the second impeller 62 includes a discharge portion 62a provided on the outer periphery of the second impeller 62 and a suction portion 62b provided on one main surface of the second impeller 62. The second impeller 62 is housed in the second pump casing 61 with the suction portion 62b facing upward in the axial direction.

[0046] The second pump group 33A includes a plurality of second pump casings 61 and a central casing 34 stacked together to define a second casing flow passage 33a in which a plurality of openings 74 communicate with each other in the axial direction.

[0047] In this embodiment, the first pump group 32A and the second pump group 33A have the same number of first impellers 42 and second impellers 62, but the numbers may be different. Furthermore, the first pump group 32A and the second pump group 33A may have different design values ​​such as blade diameter, suction diameter, etc.

[0048] 7 and 8, the central casing 34 includes an inner cylinder portion (third inner cylinder portion) 81, an outer cylinder portion (third outer cylinder portion) 82 covering the inner cylinder portion 81, and a plurality of ribs (third ribs) 83 integrally connecting the inner cylinder portion 81 and the outer cylinder portion 82. The central casing 34 is connected to the first pump portion 32 at the uppermost stage and the second pump portion 33 at the lowermost stage. In other words, the central casing 34 is connected to the secondary side of the first pump group 32A and the secondary side of the second pump group 33A. The central casing 34 has a different shape from the first pump casing 41 and the second pump casing 61.

[0049] The central casing 34 houses therein the first impeller 42 and the second impeller 62. The central casing 34 also constitutes an ascending flow passage 34a which is a part of the first flow passage 101 that guides water pressure-fed upward from the housed first impeller 42 to the second casing flow passage 33a, and a descending flow passage 34b which is a part of the second flow passage 102 that guides water pressure-fed downward from the housed second impeller 62 to the first casing flow passage 32a.

[0050] The inner cylinder 81 has a plate portion 81a that defines the center in the axial direction. The inner cylinder 81 has a storage portion 41a that stores the first impeller 42 provided on the lower side defined by the plate portion 81a, and a storage portion 61a that stores the second impeller 62 provided on the upper side. That is, the central casing 34 constitutes a part of the first pump portion 32 and a part of the second pump portion 33. In addition, a cylindrical liner ring portion that faces a sleeve provided on the pump main shaft 22 with a small gap therebetween is provided in the center of the plate portion 81a.

[0051] 1, an underwater bearing 81b is provided on the liner ring portion of the plate portion 81a. The underwater bearing 81b is inserted, for example, from the high pressure side to the low pressure side of the first pump group 32A or the second pump group 33A.

[0052] The outer cylinder portion 82 is integrally connected to the inner cylinder portion 81 by a plurality of ribs 83. The plurality of ribs 83 are formed in the same number and at the same positions as the first pump casing 41 and the second pump casing 61. Such an outer cylinder portion 82 has a plurality of openings 91 that are defined by the plate portion 81a of the inner cylinder portion 81 and the plurality of ribs 83 and communicate with the upper and lower sides of the inner cylinder portion 81. The openings 91 are formed in the same number and shape as the openings 54, 74 of the first pump casing 41 and the second pump casing 61.

[0053] The outer cylinder portion 82 has an engaging portion (third engaging portion) 82a or an engaged portion (third engaged portion) 82b that engages with the engaged portion 52b or the engaging portion 52a of the adjacent first pump casing 41, and an engaged portion 82b or an engaging portion 82a that engages with the engaging portion 72a or the engaged portion 72b of the adjacent second pump casing 61. The outer cylinder portion 82 of the central casing 34 includes a convex portion 82c and a concave portion 82d formed at predetermined positions in the circumferential direction, for example, at the upper and lower ends. Here, the specified position is a position where the convex portion 82c and the concave portion 82d provided on the outer tube portion 82 of the central casing 34 engage with the convex portion 52c or the concave portion 52d of the outer tube portion 52 of the adjacent first pump casing 41, and the convex portion 72c or the concave portion 72d of the outer tube portion 72 of the second pump casing 61, and when assembled with the adjacent first pump casing 41 and second pump casing 61, the ribs 53, 73, 83 of the first pump casing 41, the second pump casing 61 and the central casing 34 face each other in the axial direction, in other words, are at the same position circumferentially.

[0054] The engaging portion 82a and the engaged portion 82b are formed so that one can be inserted into the other. For example, the outer diameter of the engaging portion 82a is formed to be the same as the inner diameter of the engaged portion 82b or slightly smaller than the inner diameter of the engaged portion 82b, and the engaging portion 82a is inserted into the engaged portion 82b.

[0055] The protrusion 82c engages with, for example, a recess 72d provided in the outer cylinder portion 72 of the adjacent second pump casing 61, and restricts circumferential movement of the central casing 34 and the second pump casing 61. For example, the protrusion 82c is provided on the outer circumferential surface of the outer cylinder portion 82. For example, the protrusion 82c is a columnar protrusion formed integrally with the outer circumferential surface of the central casing 34.

[0056] The recess 82d is provided, for example, in the engaged portion 82b which is the lower end side of the central casing 34. The recess 82d engages, for example, with a protrusion 52c provided on the outer cylinder portion 52 of the adjacent first pump casing 41, and restricts circumferential movement of the central casing 34 and the first pump casing 41. The recess 82d is provided on the outer circumferential surface of the outer cylinder portion 82. For example, the protrusion 82c is a columnar depression provided in the engaged portion 82b, specifically, a notch provided across the outer circumferential surface and inner circumferential surface of the engaged portion 82b.

[0057] Such convex portion 82c and concave portion 82d may be provided in one or more.

[0058] The central casing 34 having such an outer cylinder portion 82 aligns the positions of the recess 52d of the outer cylinder portion 52 of the first pump casing 41 and the protrusion 72c of the outer cylinder portion 72 of the second pump casing 61, the protrusion 82c and the recess 82d in the circumferential direction, the engaging portion 82a engages with the engaged portion 72b of the second pump casing 61, the engaged portion 82b engages with the engaging portion 52a of the first pump casing 41, the protrusion 82c engages with the recess 72d, and the recess 82d engages with the protrusion 52c. Thus, the central casing 34 is connected to the first pump casing 41 and the second pump casing 61 at predetermined positions in the axial and circumferential directions.

[0059] Each of the plurality of openings 91 includes a first opening 91a and a second opening 91b that are formed by dividing the opening 91 into two in the circumferential direction.

[0060] The first opening 91a is configured such that a lower side of the inner cylinder portion 81 defined by the plate portion 81a opens to the inner circumferential surface of the inner cylinder portion 81, and an upper side is closed to the inner circumferential surface of the inner cylinder portion 81. The lower side of the first opening 91a that opens to the inner circumferential surface of the inner cylinder portion 81 continues to the storage portion 41a, and an upper side that is closed to the inner circumferential surface of the inner cylinder portion 81 continues to the opening 74 of the second pump casing 61.

[0061] The second opening 91b opens to the inner circumferential surface of the inner cylinder portion 81 at an upper side thereof defined by the plate portion 81a, and closes to the inner circumferential surface of the inner cylinder portion 81 at a lower side thereof. The second opening 91b is continuous with the storage portion 61a at an upper side thereof that opens to the inner circumferential surface of the inner cylinder portion 81, and closes to the inner circumferential surface of the inner cylinder portion 81 at a lower side thereof that continues to the opening 54 of the first pump casing 41.

[0062] The central casing 34 also includes guide vanes 92 disposed in the storage sections 41a and 61a. The guide vanes 92 guide the water discharged from the first impeller 42 and the second impeller 62 from the storage sections 41a and 61a to the first opening 91a and the second opening 91b.

[0063] In the central casing 34, the storage section 41a of the inner cylinder 81 and the multiple first openings 91a form an upward flow passage 34a that connects the secondary side of the first pump group 32A and the second casing flow passage 33a of the second pump group 33A. In addition, in the central casing 34, the storage section 61a of the inner cylinder 81 and the multiple second openings 91b form a downward flow passage 34b that connects the secondary side of the second pump group 33A and the first casing flow passage 32a of the first pump group 32A.

[0064] The casing cover 35 covers the uppermost second pump casing 61. The casing cover 35 forms a flow path that guides the water pumped from the suction port 31a of the flow path cover 31 through the first impeller 42 and via the upward flow path 34a of the central casing 34 and the second casing flow path 33a to the second impeller 62 of the uppermost second pump section 33.

[0065] In addition, the spaces between adjacent first pump casings 41, between the first pump casing 41 and the central casing 34, between the central casing 34 and the second pump casing 61, between adjacent second pump casings 61, between the first pump casing 41 and the flow path cover 31, and between the second pump casing 61 and the casing cover 35 are sealed with sealing members such as O-rings to prevent internal water from leaking.

[0066] Next, examples of the configurations of the convex portions 52c, 72c, 82c and the concave portions 52d, 72d, 82d thus provided on the first pump casing 41, the second pump casing 61 and the central casing 34, respectively, will be described below.

[0067] The convex portions 52c, 72c, 82c provided on the first pump casing 41, the second pump casing 61 and the central casing 34, respectively, are different in shape and / or number, and the recessed portions 52d, 72d, 82d provided on the first pump casing 41, the second pump casing 61 and the central casing 34, respectively, are different in shape and / or number and are formed so as to be engageable with the corresponding convex portions 52c, 72c, 82c.

[0068] The convex portions 52c of the multiple first pump casings 41 may be the same or different in shape and / or number. The convex portions 72c of the multiple second pump casings 61 may be the same or different in shape and / or number.

[0069] The different shapes of the convex portions 52c, 72c, 82c and the concave portions 52d, 72d, 82d mean, for example, that at least one of the circumferential width (thickness), axial length (height), radial width (thickness), external shape of the protrusions (convex portions) and depressions (concave portions), such as rectangular cylinder, cylindrical, polygonal cylinder, polygonal pyramid, cone, polygonal truncated pyramid, truncated cone, irregular cylinder, etc., and the circumferential positions provided on each casing 41, 61, 34 are different, and that the convex portions and concave portions can engage with each other in combinations other than the paired convex portions and concave portions, or that even if the convex portions can be inserted into the concave portions, there will be a movement (displacement) in the circumferential direction, and it will be possible to visually confirm that the combination of the convex portions and concave portions is not correct. In this way, the convex portions 52c, 72c, 82c and the concave portions 52d, 72d, 82d can be appropriately varied, for example, in terms of circumferential width (thickness), axial length (height), radial width (thickness), external shape, and circumferential position and number provided on each casing 41, 61, 34, so that only corresponding casings 41, 61, 34 can be assembled together.

[0070] Specifically, the convex portions 52c and the concave portions 52d formed on the first pump casings 41 of the first pump group 32A may have the same shape and number, or may have different shapes and / or numbers. The convex portions 72c and the concave portions 72d formed on the second pump casings 61 of the second pump group 33A are set to have a different shape and / or number from the convex portions 52c and the concave portions 52d formed on the first pump casing 41 in order to prevent the first pump casing 41 from being mistakenly used for the second pump group 33A. Moreover, the convex portions 72c and the concave portions 72d formed on the second pump casings 61 of the second pump group 33A may have the same shape and number, or may have different shapes and / or numbers. The convex portions 82c and concave portions 82d formed in the central casing 34 are set to a shape and number corresponding to the convex portions 52c or concave portions 52d of the first pump casing 41 and the concave portions 72d or convex portions 72c of the second pump casing 61 so as to be engageable with the adjacent first pump casing 41 and second pump casing 61.

[0071] For example, Fig. 9 shows an example in which the circumferential width (thickness), axial length (height, depth), radial width (thickness), outer shape and number of the protrusions 52c, 72c, 82c and the recesses 52d, 72d, 82d are the same, but the circumferential positions at which they are provided on the casings 41, 61, 34 are different. For example, Fig. 9 shows an example in which the casings 41, 61, 34 are provided with two protrusions 52c, 72c, 82c and two recesses 52d, 72d, 82d spaced apart by 90° in the circumferential direction, and an example in which the protrusions 52c, 72c, 82c and two recesses 52d, 72d, 82d are provided with two protrusions 52c, 72c, 82c and two recesses 52d, 72d, 82d spaced apart by 180° in the circumferential direction. As shown in FIG. 9, the convex portions 52c, 72c, 82c and the concave portions 52d, 72d, 82d can be engaged with each other when arranged at 90° intervals and when arranged at 180° intervals, but cannot be engaged with each other when arranged at 90° intervals or 180° intervals.

[0072] 10 shows an example in which the circumferential width (thickness), radial width (thickness) and outer shape of the convex portions 52c, 72c, 82c and the concave portions 52d, 72d, 82d are the same, but the axial length (height, depth) and number are different. For example, FIG. 10 shows an example in which the convex portions 52c, 72c, 82c and the concave portions 52d, 72d, 82d are provided one at a time in the circumferential direction (shown in the upper part of FIG. 10) and an example in which the convex portions 52c, 72c, 82c and the concave portions 52d, 72d, 82d are provided two at a time in the circumferential direction and are lower in height than the example in which one is provided (the convex portion and the concave portion in the upper example of FIG. 10) (shown in the lower part of FIG. 10). As shown in FIG. 10, the protrusions 52c, 72c, 82c and the recesses 52d, 72d, 82d can be engaged with each other when one is provided and when two are provided, but cannot be engaged with each other when one is provided and when two are provided.

[0073] As described above, the first pump casing 41, the second pump casing 61, and the central casing 34 have different shapes and / or numbers of the convex parts 52c, 72c, 82c provided thereon, so that the corresponding casings can be engaged with each other and non-corresponding casings can be prevented from engaging with each other. This makes it possible to prevent improper assembly of the first pump casing 41, the second pump casing 61, and the central casing 34, such as erroneously using the first pump casing 41 as the second pump casing 61. In addition, the non-corresponding convex parts 52c, 72c, 82c and concave parts 52d, 72d, 82d do not engage with each other, or even if they do engage, the casings 41, 61, 34 move, so that it is easy to visually determine whether or not an assembly error has occurred.

[0074] Next, a description will be given of the operation of the multi-stage pump 1. In the multi-stage pump 1, when the motor main shaft 21 rotates due to the drive of the motor 11, the pump main shaft 22 connected via the shaft coupling 23 rotates. As the pump main shaft 22 rotates, the first impeller 42 and the second impeller 62 fixed to the pump main shaft 22 rotate accordingly.

[0075] As the first impeller 42 rotates, water is sucked in through the suction portion 42b of the first impeller 42, and the pressure of the water sucked in inside the first impeller 42 is increased, causing the water to be discharged from the discharge portion 42a of the first impeller 42. In this manner, the water sucked in through the suction portion 42b of the first impeller 42 passes through the inside of the first impeller 42 and the first pump casing 41, and then passes through the first impeller 42, and is pumped from the suction port 31a of the passage cover 31 to the upward passage 34a of the central casing 34.

[0076] Next, the water pumped to the upward flow passage 34a is guided to the uppermost second pump section 33 via the second casing flow passage 33a and the casing cover 35. The water guided to the uppermost second pump section 33 is sucked through the suction section 62b of the rotating second impeller 62, is pressurized within the second impeller 62, and is discharged from the discharge section 62a of the second impeller 62. In this manner, the water sucked through the suction section 62b of the second impeller 62 passes through the interior of the second impeller 62 and the second pump casing 61, sequentially passes through the second impeller 62, and is pumped downward from the lowermost second pump section 33 to the downward flow passage 34b of the central casing 34.

[0077] The water pumped to the descending flow passage 34b is guided to the discharge port 31b of the flow passage cover 31 via the first casing flow passage 32a, and is discharged from the discharge port 31b.

[0078] According to the multi-stage pump 1 configured in this manner, the stacked first pump casings 41, the central casing 34, and the second pump casings 61 are provided with the convex portions 52c, 72c, 82c and the concave portions 52d, 72d, 82d that engage with each other in the circumferential direction. With this configuration, the circumferential (axial) positions of the casings 41, 34, 61 can be aligned to predetermined positions. Therefore, the ribs 53, 73, 83 can be aligned in the circumferential direction.

[0079] The ribs 53, 73, 83 divide each of the casing flow paths 32a, 33a into a plurality of sections around the axis (circumferential direction). Therefore, in the multi-stage pump 1, the ribs 53, 73, 83 face each other in the axial direction, and the presence of the ribs 53, 73, 83 in the direction of water flow in the first flow path 101 and the second flow path 102 can be suppressed, thereby suppressing an increase in flow path resistance, etc. Therefore, the multi-stage pump 1 can prevent assembly defects caused by the presence of the ribs 53, 73, 83 in the direction of water flow in the first flow path 101 and the second flow path 102.

[0080] Furthermore, the ribs 53, 73, 83 divide each of the casing flow passages 32a, 33a into a plurality of sections around the axis (circumferential direction), and thus the swirl component of the flow velocity of the water passing through the first casing flow passage 32a and the second casing flow passage 33a is reduced by the ribs 53, 73, 83. A part of the energy of the reduced flow velocity is converted into pressure energy, and the head of the pump is increased. In this way, the multi-stage pump 1 can improve the pump efficiency by converting a part of the flow velocity energy into pressure energy by the ribs 53, 73, 83. Furthermore, the strength of the pump 13 can be improved by using the first pump casing 41, the second pump casing 61, and the central casing 34 having the ribs 53, 73, 83.

[0081] Further, the first casing flow path 32a and the second casing flow path 33a are formed by stacking a plurality of first pump casings 41 and a plurality of second pump casings 61, respectively, and have continuous openings 54, 74. That is, the first casing flow path 32a and the second casing flow path 33a are formed without requiring any other components than the first pump casing 41 and the second pump casing 61.

[0082] Furthermore, by configuring the convex portions 52c, 72c, 82c and the concave portions 52d, 72d, 82d as described above, it is possible to prevent incorrect assembly of the casings 41, 34, 61. Therefore, the multi-stage pump 1 is easier to assemble, and assembly defects can be prevented.

[0083] As described above, according to the multi-stage pump 1 according to one embodiment of the present invention, assembly is easy and assembly defects can be prevented.

[0084] The present invention is not limited to the above-mentioned embodiment. For example, in the above-mentioned example, the pump 13 of the multi-stage pump 1 is described as having the first pump group 32A that forms an upward flow, the second pump group 33A that forms a downward flow, and the central casing 34 provided between the first pump group 32A and the second pump group 33A, but is not limited thereto. For example, the multi-stage pump 1 may be configured to have only the first pump group 32A or only the second pump group 33A. Even in such a configuration, the multi-stage pump 1 may be configured to provide the convex parts 52c, 72c and the concave parts 52d, 72d on the pump casings 41, 61. Even in such a configuration, the shapes and numbers of the convex parts 52c, 72c and the concave parts 52d, 72d of the pump casings 41, 61 can be changed.

[0085] In the above-mentioned example, specific examples of the shape and number of the protrusions and recesses of each casing are different in at least one of the circumferential width (thickness), axial length (height), radial width (thickness), outer shape, and circumferential position and number of the casings 41, 61, and 34, but are not limited to this. In other words, any configuration can be appropriately set as long as it can prevent assembly errors of each casing or improve identifiability. Furthermore, the different shapes or numbers of protrusions and recesses may be provided on adjacent casings among the multiple casings to prevent assembly errors. In the above example, the engaging portions 52a, 72a, 82a and the convex portions 52c, 72c, 82c are provided above the casings 41, 34, 61, and the engaged portions 52b, 72b, 82b and the concave portions 52d, 72d, 82d are provided below the casings 41, 34, 61, but the present invention is not limited to this. The first pump casing 41 at the bottom may not have the concave portion 52d, and the second pump casing 61 at the top may not have the convex portion 72c. As another example, the first pump casing 41 may have the convex portion 52c above and the concave portion 52d below, the second pump casing 61 may have the concave portion 72d above and the convex portion 72c below, and the central casing 34 may have only the concave portion 82d above and below.

[0086] Similarly, as another example, a convex portion 52c may be provided below the first pump casing 41 and a concave portion 52d may be provided above it, a concave portion 72d may be provided below the second pump casing 61 and a convex portion 72c may be provided above it, and only a convex portion 82c may be provided above and below the central casing 34.

[0087] In the above example, the protrusions 52c, 72c, 82c are columnar and integrally formed on the outer circumferential surface of each casing 41, 61, 34, but are not limited thereto. For example, the protrusions 52c, 72c, 82c may be keys or pins embedded or fitted in each casing 41, 61, 34, or may be provided on the end surface of each casing 41, 61, 34. Similarly, the recesses 52d, 72d, 82d may be appropriately set as long as they can engage with the protrusions 52c, 72c, 82c, and when the protrusions 52c, 72c, 82c are keys or pins, the recesses 52d, 72d, 82d may be key grooves or holes into which the keys or pins can be inserted.

[0088] In the above-mentioned example, the multi-stage pump 1 is described as a vertical multi-stage pump, but the multi-stage pump 1 is not limited thereto. For example, as in the multi-stage pump 100 according to another embodiment shown in Figs. 11 and 12, the multi-stage pump 100 may be a horizontal multi-stage pump in which the main shaft 12 (pump main shaft 22) extends in a direction perpendicular to the direction of gravity. As shown in Figs. 11 and 12, for example, the horizontal multi-stage pump 100 has a plurality of casings 141 stacked, and an impeller 42 is housed in each casing 141. For example, as shown in Fig. 12, the casing 141 is formed in an elliptical shape when viewed in the axial direction, and a drain port 141a is provided on the lower end side in the position in which the multi-stage pump 1 is installed. The casing 141 has, for example, one or more convex portions 52c and concave portions 52d that are engaged with each other. Therefore, in the multi-stage pump 100, by engaging the convex portion 52c and the concave portion 52d, the casing 141 can be arranged in the same posture so that the drain port 141a is at the same position around the axis. Also, even if the casing 141 has an elliptical shape in the axial direction, alignment is easy. Thus, the multi-stage pump 100 is easy to assemble and assembly defects can be prevented, similar to the multi-stage pump 1 described above.

[0089] The present invention is not limited to the above-mentioned embodiment, and can be modified in various ways without departing from the gist of the present invention. The embodiments may be combined as appropriate, and in that case, the combined effect can be obtained. Furthermore, the above-mentioned embodiment includes various inventions, and various inventions can be extracted by combinations selected from the multiple components disclosed. For example, if the problem can be solved and the effect can be obtained even if some components are deleted from all the components shown in the embodiment, the configuration from which the components are deleted can be extracted as an invention. [Explanation of symbols]

[0090] Reference Signs List 1, 100... multi-stage pump, 11... motor, 11a... motor casing, 12... main shaft, 13... pump, 21... motor main shaft, 22... pump main shaft, 23... shaft coupling, 22a... mechanical seal, 31... flow passage cover, 31a... suction port, 31b... discharge port, 32A... first pump group, 32... first pump section, 32a... first casing flow passage, 33A... second pump group, 33... second pump section , 33a...second casing passage, 34...central casing, 34a...ascending passage, 34b...descending passage, 35...casing cover, 41...first pump casing, 41a...storage section, 41b...return passage, 41c...guide vane, 41d...return vane, 41e...liner ring, 41f...underwater bearing, 42...first impeller, 42a...discharge section, 42b...suction section, 51...inner cylinder section, 52...outer cylinder portion, 52a...engagement portion, 52b...engaged portion, 52c...projection portion, 52d...recessed portion, 53...rib, 54...opening, 61...second pump casing, 61a...storage portion, 61b...return flow passage, 61c...guide vane, 61d...return vane, 61e...liner ring, 62...second impeller, 62a...discharge portion, 62b...suction portion, 71...inner cylinder portion, 72...outer cylinder portion, 72a...engagement portion, 72b...engaged portion, 7 2c...convex portion, 72d...concave portion, 73...rib, 74...opening, 81...inner cylinder portion, 81a...plate portion, 81b...underwater bearing, 82...outer cylinder portion, 82a...engaging portion, 82b...engaged portion, 82c...convex portion, 82d...concave portion, 83...rib, 91...opening, 91a...first opening, 91b...second opening, 92...guide vane, 101...first flow path, 102...second flow path, 141...casing, 141a...drain outlet.

Claims

1. The main axis and A plurality of impellers provided on the main shaft; A plurality of casings that house the impellers and are stacked on one another; A protrusion provided on each of the plurality of casings; a recess provided on each of the plurality of casings and adapted to engage with the protrusion of an adjacent casing around an axis; Equipped with A multi-stage pump, wherein the convex portions and the concave portions provided on any adjacent casings among the plurality of casings differ in at least one of circumferential width, axial length, radial width, outer shape, circumferential position, and number.

2. The plurality of casings are formed in different shapes, The multi-stage pump according to claim 1 , wherein the convex portions and the concave portions are formed in different shapes or in different numbers for each of the plurality of casings having different shapes.

3. The plurality of casings include a plurality of first pump casings that are stacked to define a first casing flow path around the periphery, the first casing flow path allowing flow from above to below; a plurality of second pump casings having a shape different from that of the first pump casings, the second pump casings being arranged above the plurality of first pump casings and stacked to form a second casing flow path around the first pump casings, the second casing flow path flowing upward from the secondary side of the first pump casing; 3. The multi-stage pump according to claim 2, further comprising: a central casing having a shape different from that of the first pump casing and the second pump casing, the central casing constituting an ascending passage connecting the first pump casing in the uppermost stage and the second casing passage, and a descending passage connecting the second pump casing in the lowermost stage and the first casing passage.

4. the first pump casing has a first inner cylinder portion, a first outer cylinder portion covering the first inner cylinder portion, and a plurality of first ribs integrally connecting the first inner cylinder portion and the first outer cylinder portion, and the first casing flow path is defined by an opening formed by a part of an outer circumferential surface of the first inner cylinder portion, a part of an inner circumferential surface of the first outer cylinder portion, and circumferentially opposing surfaces of two adjacent first ribs; 4. The multi-stage pump according to claim 3, wherein the second pump casing has a second inner cylinder portion, a second outer cylinder portion covering the second inner cylinder portion, and a plurality of second ribs integrally connecting the second inner cylinder portion and the second outer cylinder portion, and the second casing flow path is formed by an opening formed by a portion of an outer circumferential surface of the second inner cylinder portion, a portion of an inner circumferential surface of the second outer cylinder portion, and circumferentially opposing surfaces of two adjacent second ribs.

5. The central casing comprises: a third inner cylinder portion having a plate portion defining a center in an axial direction; A third outer cylinder portion covering the third inner cylinder portion; a plurality of third ribs integrally connecting the third inner cylinder portion and the third outer cylinder portion; a plurality of openings that are partitioned by the plate portion and the plurality of third ribs, and that are open on one side of an upper side or a lower side and closed on the other side, thereby constituting the upward flow path and the downward flow path; The multi-stage pump of claim 4 .

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