JP7493761B2 - Multi-stage pump - Google Patents

Description

The present invention relates to a multi-stage pump having multiple impellers and casings.

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). A multi-stage pump has a pump section with multiple stages. The pump section is formed by an impeller and a pump casing.

JP 2014-74359 A

The above-mentioned multi-stage pump has multiple pump stages, but if the casings of these multiple pump stages have 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 to prevent assembly defects.

Therefore, the present invention aims to provide a multi-stage pump that is easy to assemble and prevents assembly defects.

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, a convex portion provided on the plurality of casings, and a concave portion provided on the plurality of casings that engages with the convex portion of an adjacent casing around the axis , the plurality of casings having an inner tube portion, an outer tube portion covering the inner tube portion, and a plurality of ribs that integrally connect the inner tube portion and the outer tube portion, the openings between the adjacent ribs form a casing flow path that communicates in the axial direction, the plurality of ribs of the adjacent casings are disposed at positions facing each other in the axial direction, the convex portion is a columnar protrusion provided on the outer peripheral surface of the outer tube portion, and the concave portion is a columnar depression provided on the outer peripheral surface of the outer tube portion.

The present invention provides a multi-stage pump that is easy to assemble and prevents assembly defects.

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; FIG. 2 is a perspective view showing the configuration of a first pump casing and a second pump casing used in the multi-stage pump. 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. 4 is a plan view showing a configuration of a secondary side in a fluid flow direction of a first pump casing and a second pump casing used in the multi-stage pump; FIG. FIG. 2 is a perspective view showing the configuration of the first pump casing and the second pump casing in the same embodiment, partially in cross section. FIG. 2 is a cross-sectional view showing the configuration of a first impeller and a second impeller used in the multi-stage pump. FIG. 2 is a perspective view showing the configuration of a central casing used in the multi-stage pump. FIG. 2 is a perspective view showing the configuration of the central casing in partial cross section. FIG. 11 is an explanatory diagram showing an example of a relationship between convex portions and concave portions of each casing in the second embodiment. FIG. 13 is an explanatory diagram showing an example of a relationship between convex portions and concave portions of each casing in the third embodiment. FIG. 13 is an explanatory diagram showing an example of a relationship between convex portions and concave portions of each casing in the fourth embodiment. FIG. 13 is an explanatory diagram showing an example of a relationship between convex portions and concave portions of each casing in the fifth embodiment. FIG. 11 is a side view, partially in cross section, showing the configuration of a multi-stage pump according to another embodiment of the present invention. FIG. 2 is a partial cross-sectional view illustrating the configuration of a pump casing of the pump.

The configuration of the multi-stage pump 1 according to the first embodiment of the present invention will be described below with reference to Figures 1 to 12.

1 is a cross-sectional view showing the configuration of a multi-stage pump 1 according to one 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 in a partial 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 in a partial cross section. 9 to 12 are explanatory diagrams showing the relationship between the convex portions 52c, 72c, and 82c and the concave portions 52d, 72d, and 82d provided on the casings 41, 34, and 61 in the second to fifth embodiments, respectively.

As shown in FIG. 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.

As shown in FIG. 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.

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 bearings within the motor casing.

As shown in FIG. 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 that multiple impellers provided in the pump 13 can be fixed to the main shaft 12. The main shaft 12 is configured, for example, by a motor main shaft 21, a pump main shaft 22, and a shaft coupling 23.

The pump main shaft 22 is disposed in the pump 13. The pump main shaft 22 is formed so that multiple impellers 42, 62 provided in the pump 13 can be fixed. The pump main shaft 22 is one of the components of the pump 13.

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 accordance with the rotation of the motor main shaft 21.

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 path 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 is 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 the gap between the main shaft 12 and the mechanical seal 22a. As shown in FIG. 1, the intake port 31a of the flow path cover 31 forms a flow path to the first pump section 32 at the lowest stage. The discharge port 31b of the flow path cover 31 forms a flow path that is continuous with the first casing flow path 32a (described later) of the first pump group 32A.

In addition, the impellers 42, 62 of the first pump group 32A and the second pump group 33A are arranged facing in opposite directions, so that the water pumping directions are set in opposite directions 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.

The first pump group 32A is formed by stacking multiple first pump units 32. The first pump units 32 pump water upwards by pressure. The first pump units 32 include a first pump casing 41 and a first impeller 42 that is fixed to the pump main shaft 22 and housed in the first pump casing 41.

As shown in Figures 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 that covers the inner cylinder portion 51, and a plurality of ribs (first ribs) 53 that integrally connect 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 portion of the outer peripheral surface of the inner cylinder portion 51, a portion of the inner peripheral surface of the outer cylinder portion 52, and the circumferentially opposing surfaces of two adjacent ribs 53. The multiple openings 54 are provided at equal intervals.

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 passage 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.

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

The first pump casing 41 is also formed so that it can be connected to the vertically adjacent first pump casings 41, the central casing 34, and the flow path cover 31.

2 to 5, the outer tube portion 52 of the first pump casing 41 has an engaging portion (first engaging portion) 52a at the upper or lower end, and an engaged portion (first engaged portion) 52b at the lower or upper end that engages with the engaging portion 52a. Also, as shown in FIGS. 2 to 5, the outer tube portion 52 of the first pump casing 41 includes, for example, a convex portion 52c and a concave portion 52d formed at a predetermined position in the circumferential direction. 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 adjacent first pump casings 41 face each other in the axial direction when adjacent first pump casings 41 are assembled, in other words, a position where they are in the same position in the circumferential direction.

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 slightly smaller than the engaged portion 52b, and the engaging portion 52a is inserted into the engaged portion 52b.

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

The recess 52d is provided on the outer peripheral surface of the outer tube portion 52. For example, the recess 52d is a rectangular columnar depression provided in the engaged portion 52b, and as a specific example, a notch provided across the outer peripheral surface and the inner peripheral surface of the engaged portion 52b.

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

These multiple first pump casings 41 are connected in the axial direction by aligning the positions of the convex portions 52c and concave portions 52d of adjacent outer tube portions 52 in the circumferential direction, and inserting the engaging portions 52a into the engaged portions 52b, so that the engaging portions 52a and engaged portions 52b engage in the axial direction, and the convex portions 52c and concave portions 52d engage in the circumferential direction. This allows the multiple first pump casings 41 to be connected at predetermined positions in the axial and circumferential directions.

The first pump casing 41 also has an opening that is 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 peripheral edge of the opening that faces the first impeller 42. In addition, an underwater bearing 41f is disposed in one of the openings of the multiple first pump casings 41.

The first impeller 42 is made of, for example, stainless steel or resin. As shown in Figs. 1 and 6, the first impeller 42 has a discharge portion 42a provided on the outer periphery of the first impeller 42 and a suction portion 42b provided on one main surface 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.

The first pump group 32A is configured by stacking a plurality of first pump casings 41 and a central casing 34 to form a first casing flow path 32a in which a plurality of openings 54 are connected in the axial direction.

The second pump group 33A is formed 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 top stage is the secondary side in the water flow direction, and in the multi-stage second pump group 33A, the top stage is the primary side and the bottom stage is the secondary side in the water flow direction.

2 to 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 circumferentially opposing surfaces of two adjacent ribs 73. 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. For this reason, the same drawings will be used for the explanation. However, the second pump casing 61 differs from the first pump casing 41 in the orientation of the impeller (second impeller 62) that it houses, so even if they have the same configuration, their detailed shapes and the positional relationship of each component are different.

As shown in Figures 2 to 5, the second pump casing 61 has a storage section 61a that stores the second impeller 62 therein, a return flow passage 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.

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

The second pump casing 61 is also formed so that it can be connected to the vertically adjacent second pump casings 61 and the central casing 34.

2 to 5, the outer tube portion 72 of the second pump casing 61 has an engaging portion (second engaging portion) 72a at the upper or lower end, and an engaged portion (second engaged portion) 72b at the lower or upper end that engages with the engaging portion 72a. Also, as shown in FIGS. 2 to 5, the outer tube portion 72 of the second pump casing 61 includes, for example, a convex portion 72c and a concave portion 72d formed at a predetermined position in the circumferential direction. 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 adjacent second pump casings 61 face each other in the axial direction when adjacent second pump casings 61 are assembled, in other words, a position where they are in the same position in the circumferential direction.

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 engaged portion 72b, and the engaging portion 72a is inserted into the engaged portion 72b.

The protrusion 72c engages with a recess 72d provided on the outer tube portion 72 of the adjacent second pump casing 61, restricting the circumferential movement of the second pump casing 61. For example, the protrusion 72c is provided on the outer peripheral surface of the outer tube portion 72. For example, the protrusion 72c is a rectangular columnar protrusion formed integrally with the outer peripheral surface of the outer tube portion 72.

The recess 72d is provided on the outer peripheral surface of the outer tube portion 72. For example, the recess 72d is a rectangular columnar depression provided in the engaged portion 72b, and as a specific example, a notch provided across the outer peripheral surface and the inner peripheral surface of the engaged portion 72b.

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

These multiple second pump casings 61 are connected in the axial direction by aligning the positions of the convex portions 72c and concave portions 72d of adjacent outer tube portions 72 in the circumferential direction and inserting the engaging portions 72a into the engaged portions 72b, so that the engaging portions 72a and engaged portions 72b engage in the axial direction and the convex portions 72c and concave portions 72d engage in the circumferential direction. As a result, the multiple second pump casings 61 are connected at predetermined positions in the axial and circumferential directions.

The second pump casing 61 also has an opening that is 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 that faces the second impeller 62.

The second impeller 62 is formed of, for example, stainless steel or resin. As shown in FIG. 6, the second impeller 62 has 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.

The second pump group 33A is configured by stacking multiple second pump casings 61 and a central casing 34 to form a second casing flow path 33a in which multiple openings 74 are connected in the axial direction.

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 they may have different numbers. In addition, the first pump group 32A and the second pump group 33A may have different design values such as blade diameter and suction diameter.

As shown in Figs. 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 that covers the inner cylinder portion 81, and a plurality of ribs (third ribs) 83 that integrally connect 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 top and the second pump portion 33 at the bottom. 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.

The central casing 34 houses the first impeller 42 and the second impeller 62 inside. The central casing 34 also constitutes an ascending flow passage 34a, which is 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 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.

The inner cylinder 81 has a plate 81a that defines the center in the axial direction. The inner cylinder 81 has a storage section 41a that houses the first impeller 42 provided on the lower side defined by the plate 81a, and a storage section 61a that houses the second impeller 62 provided on the upper side. In other words, the central casing 34 constitutes a part of the first pump section 32 and a part of the second pump section 33. In addition, a cylindrical liner ring section is provided in the center of the plate 81a, which faces a sleeve provided on the pump main shaft 22 via a small gap.

As shown in FIG. 1, the liner ring portion of the plate portion 81a is provided with an underwater bearing 81b. 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.

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.

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 a predetermined position in the circumferential direction, for example, at the upper and lower ends. Here, the predetermined position is a position where the convex portion 82c and the concave portion 82d provided on the outer cylinder portion 82 of the central casing 34 engage with the convex portion 52c or the concave portion 52d of the outer cylinder portion 52 of the adjacent first pump casing 41, and the convex portion 72c or the concave portion 72d of the outer cylinder portion 72 of the second pump casing 61, and when the adjacent first pump casing 41 and second pump casing 61 are assembled, the ribs 53, 73, and 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 in the same position in the circumferential direction.

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 engaged portion 82b, and the engaging portion 82a is inserted into the engaged portion 82b.

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

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 tube portion 52 of the adjacent first pump casing 41, and restricts the circumferential movement of the central casing 34 and the first pump casing 41. The recess 82d is provided on the outer peripheral surface of the outer tube portion 82. For example, the protrusion 82c is a rectangular columnar depression provided in the engaged portion 82b, and as a specific example, a notch provided across the outer peripheral surface and inner peripheral surface of the engaged portion 82b.

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

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 adjacent first pump casing 41 and the protrusion 72c of the outer cylinder portion 72 of the adjacent second pump casing 61 with the protrusion 82c and the recess 82d in the circumferential direction, engages the engaging portion 82a with the engaged portion 72b of the second pump casing 61, engages the engaged portion 82b with the engaging portion 52a of the first pump casing 41, engages the protrusion 82c with the recess 72d, and engages the recess 82d with the protrusion 52c. As a result, 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.

Each of the multiple openings 91 includes a first opening 91a and a second opening 91b, which are formed by dividing the openings into two in the circumferential direction.

The first opening 91a opens to the inner peripheral surface of the inner cylinder 81 at the lower side of the inner cylinder 81 defined by the plate portion 81a, and closes to the inner peripheral surface of the inner cylinder 81 at the upper side. The first opening 91a opens to the inner peripheral surface of the inner cylinder 81 at the lower side and continues to the storage portion 41a, and closes to the inner peripheral surface of the inner cylinder 81 at the upper side and continues to the opening 74 of the second pump casing 61.

The second opening 91b is open to the inner peripheral surface of the inner cylinder 81 at the upper side thereof, which is partitioned by the plate portion 81a, and is closed to the inner peripheral surface of the inner cylinder 81 at the lower side. The second opening 91b is continuous with the storage portion 61a at the upper side thereof, which opens to the inner peripheral surface of the inner cylinder 81, and continuous with the opening 54 of the first pump casing 41 at the lower side thereof, which is closed to the inner peripheral surface of the inner cylinder 81.

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

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

The casing cover 35 covers the second pump casing 61 at the top stage. 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 second pump section 33 at the top stage.

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 water from leaking out.

Next, the relationship between the shapes of the convex portions 52c, 72c, 82c and the concave portions 52d, 72d, 82d provided on the first pump casing 41, the second pump casing 61, and the central casing 34, respectively, will be explained using the following first to fifth examples.

[First Example]
In a first embodiment, the convex portions 52c, 72c, and 82c provided on the first pump casing 41, the second pump casing 61, and the central casing 34, respectively, have the same shape, and the concave portions 52d, 72d, and 82d provided on the first pump casing 41, the second pump casing 61, and the central casing 34, respectively, have the same shape and are formed so as to be able to engage with each of the convex portions 52c, 72c, and 82c.

By setting the convex portions 52c, 72c, 82c and the concave portions 52d, 72d, 82d in this manner, the circumferential positions of the first pump casing 41, the second pump casing 61, and the central casing 34 can be determined. This makes it easy to align the circumferential positions of the ribs 53, 73, 83, for example.

[Second Example]
9, for example, the convex portions 52c provided on the first pump casing 41 have the same shape. For example, the convex portions 72c, 82c provided on the central casing 34 and the second pump casing 61 have the same shape and are different in shape from the convex portion 52c provided on the first pump casing 41. For example, the convex portion 52c and the convex portions 72c, 82c have different circumferential widths (thicknesses), and for example, the convex portion 52c is set to be thinner than the convex portions 72c, 82c.

The recesses 52d, 82d of the first pump casing 41 and the central casing 34 have the same shape and are formed to be able to engage with the protrusions 52c. In addition, the recesses 72d of the second pump casing 61 have the same shape and are formed to be able to engage with the protrusions 72c, 82c, but have a different shape from the recesses 52d, 82d provided in the first pump casing 41 and the central casing 34. For example, the recesses 52d, 82d and the recess 72d have different circumferential widths (thickness), and for example, the recesses 52d, 82d are set to be thinner than the recess 72d.

By setting the convex portions 52c, 72c, 82c and the concave portions 52d, 72d, 82d in this manner, the circumferential positions of the first pump casing 41, the second pump casing 61, and the central casing 34 can be determined. This makes it possible to easily align the circumferential positions of, for example, each rib 53, 73, 83. In addition, the first pump casing 41 and the central casing 34 engage with each other via the convex portions 52c and the concave portions 52d, 82d, and the second pump casing 61 and the central casing 34 engage with each other via the convex portions 72c, 82c and the concave portion 72d. This prevents the first pump casing 41 from being mistakenly used as the second pump casing 61, or other assembly defects between the first pump casing 41 and the second pump casing 61.

[Third Example]
As a third embodiment, as shown in Fig. 10, in addition to the relationship between the convex portions 52c, 72c, 82c and the concave portions 52d, 72d, 82d of the second embodiment, the number of the convex portions 52c and the concave portions 52d, 82d in the circumferential direction is different from the number of the convex portions 72c, 82c and the concave portions 72d in the circumferential direction. For example, the convex portion 52c of the first pump casing 41, the concave portion 52d of the first pump casing 41, and the concave portion 82d of the central casing 34 are provided in the circumferential direction, and the convex portion 72c of the second pump casing 61, the convex portion 82c of the central casing 34, and the concave portion 72d of the second pump casing 61 are provided in the circumferential direction. With this configuration, the same effects as the second embodiment can be achieved, and further, the identifiability is improved, so that assembly defects can be prevented.

[Fourth Example]
11, in a fourth embodiment, the convex portions 52c, 72c, 82c and the concave portions 52d, 72d, 82d of the first pump casing 41, the second pump casing 61 and the central casing 34 are set to have different shapes, for example, different thicknesses, for each stage. For example, when the first pump casing 41 on the primary side in the water flow direction is set to the lowest stage as the casing located at the lowest position and the second pump casing 61 on the primary side in the water flow direction is set to the highest stage as the casing located at the highest position, the convex portions 52c, 72c, 82c and the concave portions 52d, 72d, 82d are set to become gradually thicker from the lowest stage to the highest stage.

By setting the convex parts 52c, 72c, 82c and the concave parts 52d, 72d, 82d in such a relationship, the circumferential positions of the first pump casing 41, the second pump casing 61, and the central casing 34 can be determined. This makes it possible to easily align the circumferential positions of the ribs 53, 73, 83, for example. In addition, the first pump casing 41, the central casing 34, and the second pump casing 61 are set to convex parts 52c, 72c, 82c and concave parts 52d, 72d, 82d of different widths in sequence, so that convex parts and concave parts of the same dimensions engage with each other. This prevents the first pump casing 41 from being mistakenly used as the second pump casing 61, or other assembly errors between the first pump casing 41 and the second pump casing 61. In addition, even if the pump casings 41, 61 of the first pump group 32A and the second pump group 33A are different in shape, assembly errors can be prevented.

[Fifth Example]
In the fifth embodiment, as shown in FIG. 12, in addition to the relationship between the convex portions 52c, 72c, 82c and the concave portions 52d, 72d, 82d of the fourth embodiment, the number of the convex portions 52c, 72c, 82c and the concave portions 52d, 72d, 82d is different for each stage. For example, the number of the convex portions of the pump casing on the lower stage side is set to be the same as the concave portions of the pump casing on the next stage, and the number of the convex portions and the concave portions is set to be increased by one for each stage. For example, the first pump casing 41 of the first stage, which is the lowest stage, has one convex portion 52c, the first pump casing 41 of the second stage has two convex portions 52c, and one concave portion 52d. Also, the first pump casing 41 of the third stage has three convex portions 52c, and two concave portions 52d. In this way, the number of the convex portions is set to be the same as the number of stages, and the number of the concave portions is set to be one less than the number of stages, depending on the number of stages of the casing. Such a configuration achieves the same effects as the fourth embodiment, and further makes it possible to identify in which row each casing is placed, or prevents misassembly, thereby preventing assembly errors.

Next, the operation of the multi-stage pump 1 will be described. 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.

When the first impeller 42 rotates, water is sucked into the suction portion 42b of the first impeller 42, and the water sucked into the first impeller 42 is pressurized and discharged from the discharge portion 42a of the first impeller 42. In this way, the water sucked into 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 in sequence, and is pumped from the suction port 31a of the flow path cover 31 to the upward flow path 34a of the central casing 34.

The water pumped to the ascending flow passage 34a is then 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 in 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 way, the water sucked in through the suction section 62b of the second impeller 62 passes through the second impeller 62 in sequence, via the interior of the second impeller 62 and the second pump casing 61, and is pumped downward from the lowermost second pump section 33 to the descending flow passage 34b of the central casing 34.

The water pumped to the descending flow passage 34b is then guided through the first casing flow passage 32a to the outlet 31b of the flow passage cover 31 and discharged from the outlet 31b.

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 convex portions 52c, 72c, 82c and concave portions 52d, 72d, 82d that engage with each other in the circumferential direction. With this configuration, the circumferential (axial) positions of each casing 41, 34, 61 can be aligned to a predetermined position. Therefore, each rib 53, 73, 83 can be aligned in the circumferential direction.

The ribs 53, 73, 83 divide each casing flow path 32a, 33a into multiple 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.

In addition, the ribs 53, 73, 83 divide each casing flow passage 32a, 33a into multiple sections around the axis (circumferential direction), and 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. Part of the energy of the reduced flow velocity is converted into pressure energy, and the pump head is increased. In this way, the multi-stage pump 1 can improve the pump efficiency by converting part of the flow velocity energy into pressure energy by the ribs 53, 73, 83. In addition, 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.

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, with continuous openings 54, 74. In other words, the first casing flow path 32a and the second casing flow path 33a are formed without requiring any other parts of the first pump casing 41 and the second pump casing 61.

Furthermore, by configuring the convex portions 52c, 72c, 82c and the concave portions 52d, 72d, 82d as in the first to fifth embodiments described above, it is possible to prevent incorrect assembly of the casings 41, 34, 61. Therefore, the multi-stage pump 1 is easy to assemble and can prevent assembly defects.

As described above, the multi-stage pump 1 according to one embodiment of the present invention is easy to assemble and prevents assembly defects.

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 a first pump group 32A that forms an upward flow, a second pump group 33A that forms a downward flow, and a central casing 34 provided between the first pump group 32A and the second pump group 33A, but is not limited to this. 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 portions 52c, 72c and the concave portions 52d, 72d on the pump casings 41, 61. Even in such a configuration, the shape and number of the convex portions 52c, 72c and the concave portions 52d, 72d can be changed in the pump casings 41, 61, as in the first to fifth embodiments described above.

In the above example, the first to fifth examples are given as specific examples of the shape and number of the protrusions 52c, 72c and the recesses 52d and 72d, but the present invention is not limited to these. In other words, the shape and number of the protrusions 52c, 72c and the recesses 52d and 72d can be set as appropriate as long as the configuration can prevent circumferential alignment and assembly defects of the casings and can improve identifiability.

In the above example, the engaging portion 52a, 72a, 82a and the convex portion 52c, 72c, 82c are provided above each casing 41, 34, 61, and the engaged portion 52b, 72b, 82b and the concave portion 52d, 72d, 82d are provided below each casing 41, 34, 61, but this is not limited to the above. The first pump casing 41 at the bottom may be configured not to have a concave portion 52d, and the second pump casing 61 at the top may be configured not to have a convex portion 72c. As another example, the convex portion 52c may be provided above the first pump casing 41 and the concave portion 52d below, the concave portion 72d may be provided above the second pump casing 61 and the convex portion 72c below, and only the concave portion 82d may be provided above and below the central casing 34.

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.

In the above example, the convex portions 52c, 72c, and 82c are rectangular columns formed integrally with the outer peripheral surfaces of the casings 41, 61, and 34, but are not limited thereto. For example, the convex portions 52c, 72c, and 82c may be pins embedded in the casings 41, 61, and 34, or may be provided on the end surfaces of the casings 41, 61, and 34. Similarly, the concave portions 52d, 72d, and 82d may be appropriately set as long as they can engage with the convex portions 52c, 72c, and 82c. When the convex portions 52c, 72c, and 82c are pins, the concave portions 52d, 72d, and 82d may be holes into which the pins can be inserted.

In the above example, the multistage pump 1 is described as a vertical multistage pump, but is not limited thereto. For example, as in the multistage pump 100 according to another embodiment shown in FIG. 13, the multistage pump 100 may be a horizontal multistage pump in which the main shaft 12 (pump main shaft 22) extends in a direction perpendicular to the direction of gravity. As shown in FIG. 13, for example, the horizontal multistage pump 100 has a plurality of casings 141 stacked on top of each other, and an impeller 42 is housed in each casing 141. For example, as shown in FIG. 14, 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 posture in which the multistage 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. For this reason, the multistage pump 100 can arrange the casing 141 in the same posture so that the drain port 141a is in the same position around the axis by engaging the convex portions 52c and concave portions 52d. Furthermore, even if the casing 141 has an elliptical shape in the axial direction, alignment is easy. Therefore, the multi-stage pump 100 is easy to assemble and assembly defects can be prevented, similar to the multi-stage pump 1 described above.

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.
The following provides a description equivalent to the invention described in the original claims of this application.
[1] A main shaft,
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;
A multi-stage pump.
[2] The multi-stage pump according to [1], wherein the convex portions and the concave portions are set to have different shapes or numbers for each of the plurality of casings.
[3] The plurality of casings are formed in different shapes,
The multi-stage pump according to [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.
[4] 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;
The multi-stage pump according to any one of claims [1] to [3], 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.
[5] 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,
The multi-stage pump described in [4], 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 configured by an opening formed by a portion of the outer circumferential surface of the second inner cylinder portion, a portion of the inner circumferential surface of the second outer cylinder portion, and circumferentially opposing surfaces of two adjacent second ribs.
[6] 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 to form the upward flow path and the downward flow path;
The multi-stage pump according to [5],

1, 100...multistage 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 path cover, 31a...suction port, 31b...discharge port, 32A...first pump group, 32...first pump section, 32a...first casing flow path, 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 section , 52a...engaging 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...engaging portion, 72b...engaged portion, 72 c...protruding portion, 72d...recessed 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...protruding portion, 82d...recessed 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 port.

Claims (7)

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
the plurality of casings each have an inner cylinder portion, an outer cylinder portion covering the inner cylinder portion, and a plurality of ribs integrally connecting the inner cylinder portion and the outer cylinder portion, and openings between adjacent ones of the ribs form a casing flow passage that communicates in the axial direction;
The ribs of the adjacent casings are provided at positions facing each other in the axial direction,
the protrusion is a columnar protrusion provided on an outer circumferential surface of the outer cylinder portion,
The recess is a columnar depression provided on an outer peripheral surface of the outer cylinder portion . The multi-stage pump according to claim 1, wherein the convex portions and the concave portions are set to different shapes or numbers for each of the multiple casings. 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. 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;
4. The multi-stage pump according to claim 1, 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. 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;
5. The multi-stage pump according to claim 4, 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 defined 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. 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 to form the upward flow path and the downward flow path;
The multi-stage pump according to claim 5 . the casing has an engaged portion formed at one end and an engaging portion formed at the other end and adapted to be inserted into the engaged portion of another casing;
The multi-stage pump according to claim 1 , wherein the recess is provided in the engaged portion.