Vertical multistage pump

Abstract

To provide a vertical multistage pump that can improve the efficiency of the pump.SOLUTION: A vertical multistage pump comprises: a rotating shaft; a plurality of impellers fixed to the rotating shaft; an intermediate casing 31a housing the plurality of impellers; an upper casing 31b arranged on the upper side of the intermediate casing 31a, and in which a plurality of communication holes 31b1 are formed in a peripheral wall; an outer casing arranged on the outside in the radial direction of the intermediate casing 31a and the upper casing 31b, and forming an outside flow passage S3 communicating with the plurality of communication holes 31b1; and a guide plate 9 provided between an upper opening part 8a of the intermediate casing 31a and the plurality of communication holes 31b1. The guide plate 9 comprises a curved surface made convex on the upper side in the axial direction. An outer edge part 92 of the guide plate 9 extends toward lower ends of the plurality of communication holes 31b1. The guide plate 9 comprises a fixed structure 90 fixed to at least one of the intermediate casing 31a and the upper casing 31b.SELECTED DRAWING: Figure 2A

Description

[Technical Field]

[0001] The present invention relates to a vertical multi-stage pump. [Background technology]

[0002] Patent Document 1 discloses a vertical multi-stage pump that is installed midway through the piping of a fluid facility. This vertical multi-stage pump has a rotating shaft extending vertically, multiple impellers fixed to the rotating shaft, an intermediate casing that houses the multiple impellers, and an outer casing that is disposed radially outward of the intermediate casing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2017-531757 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for improvements in the performance of such vertical multi-stage pumps, such as the suction and discharge efficiency of the pump. In conventional pumps, the flow of fluid is obstructed in the flow path between the intermediate casing and the outer casing, making it difficult to improve the suction and discharge efficiency of the pump.

[0005] The present invention has been made in consideration of the above problems, and has an object to provide a vertical multi-stage pump that can improve the efficiency of the pump. [Means for solving the problem]

[0006] (1): A vertical multi-stage pump according to one embodiment of the present invention comprises a rotating shaft, a plurality of impellers fixed to the rotating shaft, an intermediate casing that houses the plurality of impellers, an upper casing that is arranged above the intermediate casing and has a plurality of communication holes formed in its peripheral wall, an outer casing that is arranged radially outward of the intermediate casing and the upper casing and forms an outer flow path that communicates with the plurality of communication holes, and a guide plate that is provided between an upper opening of the intermediate casing and the plurality of communication holes, wherein the guide plate has a curved surface that is convex axially upward, and the outer edge of the guide plate extends toward the lower ends of the plurality of communication holes, and the guide plate has a fixed structure that is fixed to at least one of the intermediate casing and the upper casing.

[0007] (2): A vertical multi-stage pump according to (1), wherein the fixed structure is an engaging portion provided on the inner edge of the guide plate and engaging with the upper opening, and the engaging portion has a plurality of insertion holes formed therein arranged in the circumferential direction, and the engaging portion is fixed to the intermediate casing by fixing members inserted into the insertion holes.

[0008] (3): A vertical multi-stage pump according to (1) or (2), wherein the fixed structure is a protrusion provided on the outer edge of the guide plate and protruding upward, the protrusion being disposed radially inward of a column portion between circumferentially adjacent communication holes, and the protrusion being fixed to the upper casing by a fixing member inserted into an insertion hole formed in the protrusion.

[0009] (4): A vertical multi-stage pump according to any one of (1) to (3), wherein the fixed structure is a tie rod extending axially in the outer flow path, the tie rod has a curved portion that curves radially inward in a portion above the intermediate casing, at least a portion of the curved portion is provided inside the upper casing, and the outer edge portion of the guide plate is pressed from above by the curved portion of the tie rod. [Effects of the Invention]

[0010] According to the above aspect of the present invention, the efficiency of the pump can be improved. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing the overall configuration of a vertical multi-stage pump according to a first embodiment. [Figure 2A] 1 is a cross-sectional view showing the configuration of a main part of a vertical multi-stage pump according to a first embodiment. [Figure 2B] FIG. 2B is an enlarged view of part IIB in FIG. 2A. [Figure 2C] 10A and 10B are diagrams showing a fixed structure and a fixed member according to a modified example of the first embodiment. [Figure 3] FIG. 6 is a cross-sectional view showing the configuration of a main part of a vertical multi-stage pump according to a second embodiment. [Figure 4] FIG. 10 is a cross-sectional view showing the configuration of a main part of a vertical multi-stage pump according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] (First embodiment) FIG. 1 is a cross-sectional view showing the overall configuration of a vertical multi-stage pump 1 according to a first embodiment. 1, the vertical multi-stage pump 1 has a motor section 10, a coupling section 20, and a pump section 30. The pump section 30 has a rotating shaft 2. In the following description, the direction in which the central axis O of the rotating shaft 2 extends is referred to as the axial direction, the direction perpendicular to the central axis O is referred to as the radial direction, and the direction circumferentially around the central axis O is referred to as the circumferential direction. The axial direction of the vertical multi-stage pump 1 coincides with the vertical direction, and the motor section 10, coupling section 20, and pump section 30 are arranged in this order from top to bottom. However, the axial direction does not have to coincide with the vertical direction.

[0014] The motor unit 10 is disposed above the pump unit 30 and is connected to the rotary shaft 2 via a coupling 3. The motor unit 10 is supported by the pump unit 30 via a bracket 21 of the coupling unit 20. The motor unit 10 rotates at a specified rotation speed. However, the motor unit 10 may be configured to be able to rotate at low or high speed (variable speed) even when powered by a commercial power source by using an inverter or the like, regardless of the specified rotation speed.

[0015] The coupling unit 20 has a bracket 21 that surrounds the coupling 3, and a guard member 22 that is attached to the bracket 21 and covers the coupling 3. The bracket 21 has a base 21a to which the motor unit 10 is attached, legs 21b that support the base 21a, and a lid 21c from which the legs 21b stand. The base 21a is formed in an annular shape centered on the central axis O.

[0016] The leg portions 21b are connected to the lower surface of the base portion 21a at intervals in the circumferential direction. A coupling 3 is arranged between the leg portions 21b. The guard member 22 is attached to the leg portions 21b so as to close the space between the leg portions 21b. The lid portion 21c is connected to the lower ends of the leg portions 21b and covers the upper part of the pump portion 30. The lid portion 21c is formed in a generally topped cylindrical shape centered on the central axis O, and has an insertion hole 23 formed in the center thereof through which the rotating shaft 2 is inserted.

[0017] A mechanical seal 24 is disposed in the insertion hole 23. The mechanical seal 24 seals the gap between the rotating shaft 2 and the insertion hole 23, preventing fluid from leaking from the pump section 30 to the outside through the insertion hole 23. A priming valve 21c1 and an air vent valve 21c2 are disposed radially outward of the insertion hole 23 in the lid section 21c. A plurality of impellers 4 are fixed to the rotating shaft 2 at intervals in the axial direction inside the pump section 30.

[0018] The impeller 4 has a main plate 5, a side plate 6, and a plurality of blades 7. The main plate 5 is formed in a circular plate shape centered on a central axis O, and is fixed to the rotary shaft 2. The side plate 6 is formed in an annular shape coaxial with the main plate 5, and is disposed with a gap therebetween. The main plate 5 and the side plate 6 are connected via a plurality of blades 7. The space surrounded by the main plate 5, the side plate 6, and the plurality of blades 7 forms a flow path that guides fluid radially. The side plate 6 forms an inlet 8 of the impeller 4.

[0019] The pump section 30 includes a cylindrical casing 31 that houses multiple impellers 4. The casing 31 defines a multi-stage pump chamber 30A inside, which pressurizes the fluid using the impellers 4. The casing 31 includes an intermediate casing 31a, an upper casing 31b disposed above the intermediate casing 31a, a lower casing 31c disposed below the intermediate casing 31a, and an outer casing 31d disposed outside the intermediate casing 31a and the upper casing 31b.

[0020] The intermediate casing 31a is formed into a cylindrical shape with a bottom by press-forming a steel plate or the like, and has an opening in the center of the bottom through which the rotary shaft 2 is inserted. The intermediate casings 31a are stacked in multiple tiers according to the number of impellers 4. A suction plate 33 is attached by welding to the underside of the bottom of the intermediate casing 31a. Return vanes 34 are also attached by welding to the underside of the suction plate 33. A liner ring 35 is attached to the inner wall of the bottom opening of the intermediate casing 31a to prevent fluid leakage around the suction port 8 of the impeller 4. The uppermost intermediate casing 31a has an upper opening 8a that communicates pressurized liquid with the upper casing 31b. In this embodiment, the upper opening 8a is the suction port 8 of the uppermost suction plate 33. Liquid is communicated from the upper opening 8a to the upper casing 31b.

[0021] The upper casing 31b is formed in a cylindrical shape with a bottom, similar to the intermediate casing 31a, and is stacked on top of the intermediate casing 31a. A plurality of communication holes 31b1 are formed in the peripheral wall of the upper casing 31b. In the example of FIG. 1, the communication holes 31b1 are circular, and a plurality of them are arranged side by side in the circumferential direction. The shape, arrangement, and number of the communication holes 31b1 are not limited, and they may be elliptical or polygonal, and a plurality of them may be arranged side by side in the circumferential and axial directions. For example, as shown in FIG. 2A, the communication holes 31b1 may each be rectangular, with the major axis extending circumferentially, and a plurality of them may be arranged side by side in the circumferential and axial directions. The interior of the upper casing 31b serves as a second communication space S2 that allows the liquid to communicate from the upper opening 8a to the communication hole 31b1.

[0022] Although details will be described later, in this embodiment, a guide plate 9 is disposed between the upper opening 8a of the intermediate casing 31a and the communication hole 31b1. The guide plate 9 is formed in an annular shape centered on the central axis O. The guide plate 9 is formed, for example, by press-forming a steel plate or the like.

[0023] The outer casing 31d is formed in a cylindrical shape that surrounds the radially outer sides of the intermediate casing 31a and the upper casing 31b. The outer casing 31d forms a third communication space S3 (also referred to as an outer flow path S3) that communicates with the communication hole 31b1 radially outward from the intermediate casing 31a and the upper casing 31b. The outer flow path S3 is a flow path through which liquid flows in an annular space that covers the intermediate casing 31a and the upper casing 31b when viewed from the axial direction. The upper parts of the upper casing 31b and the outer casing 31d are covered by a casing cover 31e disposed on the underside of the lid portion 21c.

[0024] The lower casing 31c forms a first communication space S1 that communicates with the suction port 8 at the lower end of the multistage pump chamber 30A, and also forms a fourth communication space S4 that communicates with the outer flow path S3 inside the outer casing 31d. The lower casing 31c has a first frame 31c1 that forms the first communication space S1 inside, and a second frame 31c2 that surrounds the outside of the first frame 31c1 and forms the fourth communication space S4 between itself and the first frame 31c1.

[0025] The first frame 31c1 is formed in a cylindrical shape (approximately dish-shaped) with a bottom and a flange 31c4 in which a communication hole 31c3 is formed. The communication hole 31c3 axially penetrates the flange 31c4, connecting the outer flow path S3 and the fourth communication space S4. The second frame 31c2 is formed in a cylindrical shape with a bottom and accommodates the first frame 31c1 in a nested manner. The outer edge of the flange 31c4 of the first frame 31c1 contacts the inner peripheral surface of the second frame 31c2, forming a gap (fourth communication space S4) between the outer peripheral surface of the first frame 31c1 and the inner peripheral surface of the second frame 31c2.

[0026] The lower casing 31c has a suction nozzle 36 extending horizontally and a discharge nozzle 37 also extending horizontally. The suction nozzle 36 penetrates and is joined to the peripheral wall of the second frame 31c2, and also penetrates and extends to the first communication space S1 through the peripheral wall of the first frame 31c1. The discharge nozzle 37 is disposed opposite the suction nozzle 36 across the central axis O. In other words, the suction nozzle 36 and the discharge nozzle 37 are disposed on the same straight line passing through the central axis O. The discharge nozzle 37 penetrates and is joined to the peripheral wall of the second frame 31c2, but does not penetrate and extends to the fourth communication space S4 through the peripheral wall of the first frame 31c1.

[0027] A pump base 32 is provided below the lower casing 31c. The pump base 32 is axially connected to the bracket 21 of the coupling unit 20 by casing bolts 32a and nuts 32b. A plurality of casing bolts 32a and nuts 32b are provided at intervals in the circumferential direction. By fastening the plurality of casing bolts 32a and nuts 32b, the multi-stage intermediate casing 31a, upper casing 31b, lower casing 31c, and casing cover 31e are clamped in the axial direction.

[0028] <Function of vertical multi-stage pump 1> In the pump section 30 configured as described above, when the impeller 4 rotates, fluid is sucked into the first communication space S1 of the lower casing 31c through the suction nozzle 36. The fluid sucked into the first communication space S1 is sucked into the first-stage impeller 4 through the suction port 8 at the lower end of the multistage pump chamber 30A and is pressurized. The fluid discharged from the first-stage impeller 4 passes through a flow path formed by the return vane 34 and the suction plate 33 and is guided to the suction side of the next-stage impeller 4.

[0029] After being pressurized in multiple stages by the multiple impellers 4, the fluid flows from the upper opening 8a into the second communication space S2 in the upper casing 31b. The fluid that flows into the second communication space S2 flows downward through the communication hole 31b1 and the outer flow path S3 formed on the outside of the upper casing 31b, and flows into the fourth communication space S4 via the communication hole 31c3. The fluid that flows into the fourth communication space S4 is discharged through the discharge nozzle 37 connected to the lower casing 31c. The discharge nozzle 37 is arranged in the same line as the suction nozzle 36, so it can be incorporated into the piping of fluid facilities in factories, etc.

[0030] In the pump section 30 of such a vertical multistage pump 1, the fluid that has flowed into the upper casing 31b is connected to the communication hole 31b1 in the upper portion, thereby changing the liquid flow path. When the fluid changes its flow path in this way, turbulence such as many swirling vortices occurs in the fluid. The turbulence may impede the flow of the fluid and cause fluid loss, which may reduce the suction and discharge performance of the vertical multistage pump 1. Here, the inventors discovered that by providing a guide plate 9 between the upper opening 8a and the communication hole 31b1, it is possible to adjust the direction of the liquid flow toward the outer flow path S3 in the second communication space S2, thereby improving the efficiency of the vertical multi-stage pump 1. The guide plate 9 will be described in detail below with reference to FIG. 2A.

[0031] <Guide plate> 2A is an enlarged view of a connection portion between the upper casing 31b and the intermediate casing 31a of the vertical multistage pump 1 according to the first embodiment. For ease of explanation, the rotating shaft, the outer casing, and the like are not shown. As shown in FIG. 2A, the guide plate 9 has an inner edge portion 91, an outer edge portion 92, and an intermediate portion 93. The inner edge portion 91 contacts the upper opening 8a. The outer edge portion 92 is located below the lower end of the communication hole 31b1 and above the upper opening 8a of the intermediate casing 31a. The outer edge portion 92 may be located at the same position as the lower end of the communication hole 31b1. The intermediate portion 93 is located between the inner edge portion 91 and the outer edge portion 92 and has a curved surface that is convex axially upward. In the cross-sectional view shown in FIG. 2A, the intermediate portion 93 has an arc-shaped curved surface that is convex toward the inside of the second communication space S2.

[0032] The guide plate 9 has a fixing structure 90 that fixes the guide plate 9 to the intermediate casing 31a or the upper casing 31b. In this embodiment, the fixing structure 90 is provided on an inner edge portion 91 of the guide plate 9, and is an engagement portion 91a that is formed by deforming the inner edge portion 91 of the guide plate 9 into an S-shape in cross section. More specifically, as shown in FIG. 2B, the inner edge portion 91 of the guide plate 9 is bent twice radially outward. This results in three overlapping metal plates at the engagement portion 91a. The three overlapping metal plates are, from the radially outer side, a first bent portion 91a1, a second bent portion 91a2, and a third bent portion 91a3. The first bent portion 91a1 is positioned radially outward of the upper opening 8a, and the upper opening 8a is inserted between the first bent portion 91a1 and the second bent portion 91a2.

[0033] The first bent portion 91a1 and the second bent portion 91a2 are connected to each other at the upper side of the first connecting portion 91c1. Therefore, the guide plate 9 can be easily positioned in the axial direction by inserting the upper opening 8a from below between the first bent portion 91a1 and the second bent portion 91a2 and bringing it into contact with the first connecting portion 91c1.

[0034] The engaging portion 91a is formed with an insertion hole 91h that passes through the engaging portion 91a in the radial direction. A plurality of the insertion holes 91h are provided in the engaging portion 91a and are aligned in the circumferential direction. In this embodiment, the insertion hole 91h is a hole that radially penetrates the second bent portion 91a2 and the third bent portion 91a3. The fixing member B is a male screw, and at least a portion of the insertion hole 91h is a female screw. The tip of the fixing member B presses against the inner circumferential surface of the upper opening 8a, thereby fixing the guide plate 9 to the upper opening 8a. In the example shown in FIG. 2B, the fixing member B is a male screw having a threaded shaft portion and a head portion provided at the end of the shaft portion. Note that the fixing member B may also be a set screw without a head portion.

[0035] The above-described method of fixing the guide plate 9 is merely an example and is not limited to the above-described method. For example, as shown in FIG. 2C , holes 8h may be formed in the upper opening 8a of the intermediate casing 31a at locations corresponding to the insertion holes 91h. In this case, the guide plate 9 is fixed to the intermediate casing 31a by the holes 8h and by a fixing member B inserted into the insertion holes 91h. In the example shown in FIG. 2C , the fixing member B is male-threaded and the holes 8h are female-threaded, so that the guide plate 9 is fixed to the upper opening 8a by the fixing member B. Alternatively, holes may be provided that penetrate the upper opening 8a, the first bent portion 91a1, the second bent portion 91a2, and the third bent portion 91a3. The fixing member B may be a metal rod, a wire, or a combination of a bolt and a nut. The intermediate casing 31a and the guide plate 9 may be joined by welding or adhesive, or may be fixed by press-fitting the engaging portion 91a of the guide plate 9 into the upper opening 8a. Alternatively, the intermediate casing 31a may have a protrusion formed thereon that fits into the insertion hole 91h instead of the hole 8h.

[0036] When the position of the guide plate 9 is fixed by the engaging portion 91a, the radial inside of the upper opening 8a is surrounded by the inner edge portion 91. As a result, the liquid discharged from the upper opening 8a is guided by the guide plate 9 and flows into the second communication space S2.

[0037] In this embodiment, the outer edge portion 92 of the guide plate 9 is connected to the boundary between the intermediate casing 31a and the upper casing 31b. More specifically, the end face of the upper end portion 31a1 of the intermediate casing 31a facing radially inward is in contact with the radially outer end face of the outer edge portion 92 of the guide plate 9. Here, the outer edge portion 92 of the guide plate 9 may be disposed above the upper end portion 31a1 of the intermediate casing 31a. The upper end portion 31a1 of the intermediate casing 31a and the outer edge portion 92 of the guide plate 9 may be fixed with a fixing member, or may be joined by welding, adhesive, or the like. The outer edge 92 of the guide plate 9 does not have to be in contact with the casing 31. More specifically, the outer edge 92 may be a free end that extends toward the lower end of the communication hole 31b1 but does not contact the casing 31. Even in such a case, the guide plate 9 formed from a metal plate has rigidity, so the guide plate 9 is unlikely to deform even in a flowing liquid and can guide the flow of the liquid in a desired direction.

[0038] In the guide plate 9, the inner edge portion 91 extends approximately parallel to the axial direction, the middle portion 93 has a curved surface that is convex upward, and the outer edge portion 92 extends approximately parallel to the radial direction toward the lower end of the communicating hole 31b1. As a result, the liquid discharged from the upper opening 8a is guided axially upward by the inner edge 91 into the second communication space S2, the flow is expanded by the middle portion 93 so that it flows radially instead of axially, and then directed toward the communication hole 31b1 by the outer edge 92. In this way, by adjusting the direction of the liquid flow in the second communication space S2, the guide plate 9 can prevent the occurrence of turbulence in the liquid flow that is likely to occur when the flow path is changed.

[0039] The vertical multi-stage pump 1 having the above-described configuration includes a rotating shaft 2, a plurality of impellers 4 fixed to the rotating shaft 2, an intermediate casing 31a accommodating the plurality of impellers 4, an upper casing 31b arranged above the intermediate casing 31a and having a plurality of communicating holes 31b1 formed in its peripheral wall, an outer casing 31d arranged radially outward of the intermediate casing 31a and the upper casing 31b and forming an outer flow path S3 communicating with the plurality of communicating holes 31b1, and a guide plate 9 provided between the upper opening 8a of the intermediate casing 31a and the plurality of communicating holes 31b1, the guide plate 9 having a curved surface that is convex axially upward, an outer edge portion 92 of the guide plate 9 extending toward the lower ends of the plurality of communicating holes 31b1, and the guide plate 9 having a fixing structure 90 fixed to at least one of the intermediate casing 31a and the upper casing 31b. According to this configuration, the guide plate 9 can prevent disturbances in the liquid flow that tend to occur when changing flow paths, thereby suppressing a decrease in the suction and discharge performance of the vertical multistage pump 1. Furthermore, performance can be improved simply by attaching the guide plate 9 to a conventional vertical multistage pump. In other words, no design changes are required other than to the attachment portion of the guide plate 9, which is advantageous because it reduces the cost of installing the guide plate 9. Furthermore, the guide plate 9 has a fixing structure 90 for fixing it to the casing 31, so it can be easily attached to the vertical multistage pump 1.

[0040] The fixed structure 90 is an engagement portion 91a that is provided on the inner edge portion 91 of the guide plate 9 and engages with the upper opening 8a, and the engagement portion 91a has a plurality of insertion holes 91h that are arranged circumferentially, and the engagement portion 91a is fixed to the intermediate casing 31a by a fixing member B that is inserted into the insertion holes 91h. According to this configuration, the guide plate 9 can be reliably fixed to the intermediate casing 31a by the engagement portion 91a provided on the inner edge portion 91 of the guide plate 9. Furthermore, since the upper opening 8a of the intermediate casing 31a engages with the engagement portion 91a, the liquid discharged from the intermediate casing 31a can be smoothly guided to the second communication space S2.

[0041] (Second embodiment) Next, a second embodiment of the present invention will be described. In the following description, the same or equivalent components as those in the above-described embodiment will be denoted by the same reference numerals, and the description thereof will be simplified or omitted.

[0042] 3 is an enlarged view of a connection portion between an upper casing 31b and an intermediate casing 31a of a vertical multistage pump 1 according to the second embodiment. For ease of explanation, the rotating shaft, outer casing, etc. are not shown. In this embodiment, the fixed structure 90 is a protrusion 92a that is provided on the outer edge 92 of the guide plate 9 and protrudes upward. The protrusion 92a is provided radially inside the pillar portion P between two circumferentially adjacent communication holes 31b1. A plurality of protrusions 92a are provided in the circumferential direction in accordance with the number of pillar portions P. Note that the number of protrusions 92a may be less than the number of pillar portions P.

[0043] The protruding portion 92a is formed with an insertion hole 92h that penetrates in the radial direction. A plurality of insertion holes 31h1 are formed in the upper casing 31b in correspondence with the positions and number of the insertion holes 92h. The upper casing 31b and the protruding portion 92a are fixed to each other by a fixing member B that passes through the insertion hole 92h and the insertion hole 31h1. In this embodiment, the fixing member B is a bolt that passes through the insertion hole 93h and the insertion hole 31h1 and a nut that fixes the bolt. The diameter of the opening of the inner edge portion 91 of the guide plate 9 is equal to or smaller than the diameter of the upper opening 8a, and the position of the inner edge portion 91 is fixed by fitting the inner edge portion 91 of the guide plate 9 radially inside the upper opening 8a.

[0044] According to the vertical multi-stage pump 1 having the above-described configuration, the fixed structure 90 is a protrusion 92a provided on the outer edge 92 of the guide plate 9 and protruding upward, the protrusion 92a being arranged radially inside the column portion P between circumferentially adjacent communicating holes 31b1, and the protrusion 92a is fixed to the upper casing 31b by a fixing member B inserted into an insertion hole 92h formed in the protrusion 92a. According to this configuration, the guide plate 9 can be reliably fixed to the upper casing 31b by the protrusions 92a provided on the outer edge 92 of the guide plate 9. Furthermore, since the protrusions 92a of the guide plate 9 are provided at positions that do not block the communication holes 31b1, the liquid in the second communication space S2 can be smoothly guided from the communication holes 31b1 to the third communication space S3.

[0045] (Third embodiment) Next, a third embodiment of the present invention will be described. In the following description, the same or equivalent components as those in the above-described embodiment will be denoted by the same reference numerals, and the description thereof will be simplified or omitted.

[0046] 4 is an enlarged view of a connecting portion between an upper casing 31b and an intermediate casing 31a of a vertical multistage pump 1 according to the third embodiment. For ease of explanation, the rotating shaft and other components are not shown. In this embodiment, the fixed structure 90 is a rod portion 94 having a tie rod 94a and a plate fixing portion 94b.

[0047] The tie rod 94a is a rod-shaped member extending axially through the third communication space S3. A lower end (not shown) of the tie rod 94a is fixed to the lower casing 31c. The tie rod 94a has a curved portion 94c that curves radially inward in a portion above the intermediate casing 31a. In the example shown in FIG. 4, the curved portion 94c that curves radially inward of the tie rod 94a constitutes the upper end 94a1 of the tie rod 94a. The curved portion 94c passes through a rod through-hole 31h2 formed in the pillar portion P of the upper casing 31b and extends to the second communication space S2. Therefore, the end face of the curved portion 94c faces radially inward. Note that the curved portion 94c may also pass through the communication hole 31b1 and extend to the second communication space S2. The tie rod 94a sandwiches the upper casing 31b and the multiple intermediate casings 31a, each including an impeller 4, between the curved portion 94c (upper end portion 94a1) and the lower end portion thereof. This allows the axial connection between the intermediate casings 31a and the upper casing 31b to be fixed by the tie rod 94a.

[0048] The plate fixing portion 94b is fixed to an end face of the curved portion 94c of the tie rod 94a. The plate fixing portion 94b is a cylindrical rod that extends in the axial direction. The plate fixing portion 94b has an upper first end 94b1 and a lower second end 94b2 in the axial direction. The first end 94b1 is fixed to the curved portion 94c of the rod portion 94, and the second end 94b2 contacts the outer edge portion 92 of the guide plate 9 and presses the outer edge portion 92 downward. As a result, the rod portion 94 fixes the position of the guide plate 9 so that the outer edge portion 92 of the guide plate 9 is located at the same position as the lower end of the communicating hole 31b1 or lower than the lower end of the communicating hole 31b1. That is, the curved portion 94c of the tie rod 94a presses the outer edge portion 92 of the guide plate 9 from above via the plate fixing portion 94b, thereby fixing the position of the guide plate 9. The plate fixing portion 94b is not limited to a cylindrical rod shape, but may be a metal plate extending in the circumferential and axial directions.

[0049] In this embodiment, the rod portion 94 has a tie rod 94a and a plate fixing portion 94b, but the plate fixing portion 94b is not an essential component and may be omitted. For example, the curved portion 94c of the tie rod 94a may directly press against the outer edge portion 92 of the guide plate 9 to fix the position of the outer edge portion 92. In this case, the positions of the curved portion 94c and the rod through hole 31h2 in the axial direction are adjusted so that the curved portion 94c of the tie rod 94a can press against the outer edge portion 92. The number of rod portions 94 may be one or more. Depending on the number of rod portions 94, one or more rod through holes 31h2 are provided in the upper casing 31b. In the present embodiment, the upper end 94a1 of the tie rod 94a is provided with a curved portion 94c that curves radially inward. However, the present invention is not limited to this example. For example, the tie rod 94a extending along the axial direction in the outer flow path S3 may have a branch portion. The tie rod 94a may have an upper end 94a1 extending upward and a curved portion 94c extending radially inward in a portion above the intermediate casing 31a. Even with this configuration, the curved portion 94c extending radially inward from the branch portion can press the outer edge portion 92 from above. The upper end 94a1 extending upward from the branch portion may be connected to the upper surface of the casing 31, or may be a free end that does not contact the casing 31.

[0050] The diameter of the opening of the inner edge portion 91 of the guide plate 9 is equal to or smaller than the diameter of the upper opening 8a, and the position of the inner edge portion 91 is fixed by fitting the inner edge portion 91 of the guide plate 9 radially inside the upper opening 8a.

[0051] In the vertical multi-stage pump 1 having the above-described configuration, the fixed structure 90 is a tie rod 94a extending axially in the outer flow path S3, and the tie rod 94a has a curved portion 94c that curves radially inward in a portion above the intermediate casing 31a, and at least a portion of the curved portion 94c is provided inside the upper casing 31b, and the outer edge portion 92 of the guide plate 9 is pressed from above by the curved portion 94c of the tie rod 94a.

[0052] According to this configuration, the rod portion 94 can securely fix the outer edge portion 92 of the guide plate 9 while fixing the stacked state of the intermediate casing 31a and the upper casing 31b. Since the tie rod 94a is a configuration that is also used in conventional vertical multi-stage pumps to fix the stacked state of multiple casings, the method of fixing the position of the guide plate 9 using the tie rod 94a can be easily applied to various vertical multi-stage pumps.

[0053] The technical scope of the present invention is not limited to the embodiments, and various modifications can be made without departing from the spirit of the present invention.

[0054] For example, the cross-sectional shape of the fixed structure 90 in the first embodiment is the S-shaped engaging portion 91a, but is not limited to the S-shaped engaging portion 91a. For example, the fixed structure 90 may not have the first bent portion 91a1 and the second bent portion 91a2, and may be fixed to the upper opening 8a by a fixing member B inserted into the insertion hole 91h.

[0055] Furthermore, in the first to third embodiments, only either the inner edge portion 91 or the outer edge portion 92 of the guide plate 9 is fixed to the casing by the fixing structure 90, but both the inner edge portion 91 and the outer edge portion 92 may be fixed to the casing by the fixing structure 90. For example, the position of the inner edge portion 91 may be fixed by the engaging portion 91a in the first embodiment, and the position of the outer edge portion 92 may be fixed by the protruding portion 92a in the second embodiment or the tie rod 94a in the third embodiment.

[0056] In addition, it is possible to replace the components in the above-described embodiments with well-known components as appropriate, without departing from the spirit of the present invention, and the above-described embodiments and variations may be combined as appropriate. [Explanation of symbols]

[0057] 1...vertical multistage pump, 2...rotating shaft, 4...impeller, 8a...upper opening, 9...guide plate, 31...casing, 31a...intermediate casing, 31b...upper casing, 31b1...communicating hole, 31c...lower casing, 31d...outer casing, 90...fixed structure, 91...inner edge portion, 91a...engagement portion, 92...outer edge portion, 92a...protruding portion, 93...intermediate portion, 94...rod portion, 94a...tie rod, 94a1...upper end portion, 94c...curved portion, B...fixed member, O...center axis, P...column portion, S1...first communicating space, S2...second communicating space, S3...outer flow path (third communicating space)

Claims

1. A rotation axis; A plurality of impellers fixed to the rotary shaft; an intermediate casing that houses the plurality of impellers; an upper casing disposed above the intermediate casing and having a plurality of communication holes formed in a peripheral wall; an outer casing disposed radially outward of the intermediate casing and the upper casing, the outer casing defining an outer flow passage communicating with the plurality of communication holes; a guide plate provided between the upper opening of the intermediate casing and the plurality of communication holes, the guide plate has a curved surface that is convex upward in the axial direction, and an outer edge portion of the guide plate extends toward lower ends of the plurality of communicating holes, The guide plate has a fixed structure fixed to at least one of the intermediate casing and the upper casing.

2. the fixed structure is an engagement portion that is provided on an inner edge portion of the guide plate and engages with the upper opening, The engaging portion is formed with a plurality of insertion holes arranged in a circumferential direction, The engaging portion is fixed to the intermediate casing by a fixing member inserted into the insertion hole. The vertical multi-stage pump according to claim 1.

3. the fixed structure is a protrusion provided on an outer edge of the guide plate and protruding upward, the protrusion is disposed radially inward of the column portion between circumferentially adjacent communication holes, The protrusion is fixed to the upper casing by a fixing member inserted into an insertion hole formed in the protrusion.

3. The vertical multi-stage pump according to claim 1 or 2.

4. the fixed structure is a tie rod extending along the axial direction in the outer flow passage, The tie rod has a curved portion that curves radially inward in a portion above the intermediate casing, and at least a portion of the curved portion is provided inside the upper casing, The outer edge portion of the guide plate is pressed from above by the curved portion of the tie rod.

3. The vertical multi-stage pump according to claim 1 or 2.

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