Pump device

Abstract

To provide a pump device which can reduce residual water after water drainage.SOLUTION: A pump device 1 includes: a plurality of impellers 62 having a shroud 622 with an inclination part 622a inclined with respect to a rotational center, and a plurality of blades 623 provided on the shroud 622; a plurality of casings 61 housing the impellers 62 and stacked on top of each other; and a partitioning panel 63 provided between adjacent casings 61 and having an inclined surface facing the inclination part 622a. In a position where the rotational center of the impeller 62 is along the gravity center direction, a top face of the partitioning panel 63 does not include a reverse-gradient where water is not naturally drained in the gravity center direction but is formed as a plane or a gradient.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a pump device having a plurality of impellers and a casing. [Background technology]

[0002] Multi-stage pumps having multiple impellers and casings are known as pump devices that supply water to skyscrapers, tower apartment buildings, etc. Such pump devices are known to have, for example, a double-cylindrical casing, with an impeller housed in the inner cylindrical portion and a flow path formed between the inner cylindrical portion and the outer cylindrical portion through which water flows after passing through the multiple impellers (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-011600 Summary of the Invention [Problem to be solved by the invention]

[0004] Such pump devices undergo performance testing by passing water through them before shipping, and are then shipped after draining the water with the rotating shaft aligned with the direction of gravity. However, if the water channel formed inside the pump device has a recess or other reverse-gradient portion, drainage may be poor, resulting in residual water. For this reason, even if the pump device is reoriented so that the axial direction of the rotating shaft is aligned with the direction of gravity or horizontally, water may not drain. If residual water remains, there is a risk of water leaking during transportation or installation after shipping. Furthermore, if gaps are provided between components in the flow path to drain the water, vortices are generated, resulting in energy loss. For this reason, there is a demand for a pump device that is less susceptible to energy loss and can reduce residual water after draining.

[0005] Furthermore, when the impeller inside the casing rotates, the water present between the casing or partition plate and the outer surface of the impeller shroud rotates in conjunction with the rotation of the impeller shroud, forming a vortex. At this time, the larger the gap between the casing or partition plate and the impeller, the larger the vortex will be, but the larger the vortex, the more energy will be wasted to maintain it, and the greater the disc friction loss will be.

[0006] In order to reduce this disc friction loss, it is effective to reduce the gap between the casing or partition plate and the impeller shroud, and to do so, it is necessary to shape the casing or partition plate so that it follows the shape of the impeller shroud. Therefore, it is necessary to incline the surfaces of the casing or partition plate that face the inclined portion of the impeller shroud along the inclination of the impeller shroud, but if a portion of the casing or partition plate is inclined, it will create a portion with a reverse gradient, such as a depression that will cause residual water.

[0007] Therefore, an object of the present invention is to provide a pump device that can suppress residual water after draining. [Means for solving the problem]

[0008] According to one aspect of the present invention, a pump device includes a shroud having an inclined portion inclined toward the center of rotation, and a plurality of impellers having a plurality of blades provided on the shroud, a plurality of casings stacked on top of each other to house the impellers, and a partition plate provided between adjacent casings and having an inclined surface facing the inclined portion, wherein when the center of rotation of the impeller is in an orientation along the direction of gravity, the upper surface of the partition plate is formed flat or sloped and does not include a reverse slope that prevents natural drainage in the direction of gravity. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a pump device that can suppress residual water after draining. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram showing, in partial cross section, the configuration of a pump device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic diagram showing the configuration of the pump device, with a partial cross section. [Figure 3] FIG. 2 is a plan view showing, in partial cross section, the configuration of a casing used in the pump device. [Figure 4] FIG. 2 is an enlarged cross-sectional view showing the configuration of a casing, an impeller, and a partition plate of the pump device. [Figure 5] FIG. 2 is a perspective view showing the configuration of a partition plate used in the pump device. [Figure 6] FIG. 2 is a perspective view showing a configuration of a central casing used in the pump device, with some parts omitted. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, the configuration of a pump device 1 according to one embodiment of the present invention will be described with reference to FIGS.

[0012] FIG. 1 is a schematic diagram showing, in partial cross section, the configuration of a pump device 1 according to one embodiment of the present invention. FIG. 2 is a schematic diagram showing, in partial cross section, the configuration of the pump device 1 from a direction rotated 90° around the rotation center of the main shaft 12. FIG. 3 is a plan view showing, in partial cross section, the configurations of a first pump casing 41 and a second pump casing 61 used in the pump device 1. FIG. 4 is a cross-sectional view showing, in enlarged form, the configurations of a second casing 61, a second impeller 62, and a second partition plate 63 of the pump device 1. FIG. 5 is a perspective view showing, in partial omission, the configurations of the partition plates 43 and 63 used in the pump device 1. FIG. 6 is a perspective view showing, in partial omission, the configuration of a central casing 34 used in the pump device 1.

[0013] As shown in Figures 1 and 2, the pump device 1 includes a motor 11, a main shaft 12, and a pump 13. For example, the pump device 1 is a multi-stage pump provided with a plurality of pumps 13. When the pump device 1 drains water from inside, the main shaft 12 is oriented in the direction of gravity. In this embodiment, the pump device 1 is, for example, a vertical pump in which the main shaft 12 extends in the direction of gravity, but it may also be a horizontal pump as long as the main shaft 12 is oriented in the direction of gravity when draining water.

[0014] 1 and 2, 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.

[0015] The motor main shaft 21 is fixed to the rotor. The motor main shaft 21 rotates as the rotor rotates. The motor main shaft 21 is supported by bearings within the motor casing.

[0016] 1 and 2, the main shaft 12 is configured to be rotatable by the motor 11. The main shaft 12 extends in the direction of gravity so as to be able to fix a plurality of impellers provided in the pump 13. The main shaft 12 is configured by, for example, a motor main shaft 21, a pump main shaft 22, and a shaft coupling 23.

[0017] The pump main shaft 22 is disposed in the pump 13. The pump main shaft 22 is formed so that a plurality of impellers 42, 62 provided in the pump 13 can be fixed to the pump main shaft 22. The pump main shaft 22 is one of the components of the pump 13.

[0018] 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 .

[0019] 1 and 2, pump 13 has multiple pump sections, each including an impeller and a casing. Specifically, pump 13 includes pump main shaft 22, flow path cover 31 that defines suction port 31a and discharge port 31b, first pump group 32A that defines an upward flow, second pump group 33A that is disposed above first pump group 32A and defines a downward flow, a central casing 34 disposed between first pump group 32A and second pump group 33A, casing cover 35, seal member 36, temporary assembly bolts 37, and main bolts 38. Furthermore, first pump group 32A and second pump group 33A of pump 13 are formed by components that do not include any internally inclined portions, but are formed by internally flat or inclined portions. In addition, between the main shaft 12 and the casing cover 35 of the pump 13, which will be described later, a mechanical seal 22a is provided, 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 them and the main shaft 12.

[0020] As shown in Fig. 1, when the pump device 1 is installed on an installation surface G1 so that the axis of the pump device 1 is vertical, the flow path cover 31 is located at the lowest part of the pump 13. As shown in Figs. 1 and 2, the suction 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 a first casing flow path 32a (described later) of the first pump group 32A. The suction port 31a and the discharge port 31b are provided at symmetrical positions around the rotation center of the main shaft 12, i.e., at 180° intervals.

[0021] Furthermore, the flow path cover 31 has a base 31c for installation on the installation surface G1, and has a plurality of fixing portions 31d for fixing the main bolts 38 to the base 31c. For example, the fixing portions 31d are holes formed in the base 31c. The fixing portions 31d are arranged on the base 31c to avoid the suction port 31a and the discharge port 31b. The number of fixing portions 31d is the same as the number of main bolts 38. The plurality of fixing portions 31d are arranged symmetrically. As a specific example, the plurality of fixing portions 31d are arranged at equal intervals around the axis, or a set of the plurality of fixing portions 31d is arranged at symmetrical positions. The fixing portions 31d are holes or the like to which the main bolts 38 can be fixed.

[0022] For example, main bolt 38 has a male threaded portion at its end, and fixing portion 31d has a female threaded portion, and main bolt 38 is screwed into fixing portion 31d, thereby fixing main bolt 38. Note that fixing of fixing portion 31d and main bolt 38 may be configured such that the end of main bolt 38 is press-fitted, or such that main bolt 38 is provided with a head portion and fixing portion 31d has a seat for receiving this head portion, or such that the end of main bolt 38 is configured in a rectangular column shape and fixing portion 31d is a rectangular column-shaped hole with a bottom, thereby restricting movement of main bolt 38 in the axial and circumferential directions.

[0023] The first pump group 32A and the second pump group 33A have their housed impellers 42, 62 arranged in opposite directions, so that the water is pumped in opposite directions in the axial direction. That is, the water flows upward in the first pump group 32A, and downward in the second pump group 33A. The pump device 1 having such first pump group 32A and second pump group 33A is a so-called self-balancing pump that can reduce thrust load.

[0024] The first pump group 32A is formed by stacking multiple first pump units 32. The first pump units 32 pump water upward by pressure. The first pump units 32 include a first pump casing 41, a first impeller 42 fixed to the pump main shaft 22 and housed in the first pump casing 41, and a first partition plate 43.

[0025] 3, the first pump casing 41 includes an inner cylindrical portion (first inner cylindrical portion) 51, an outer cylindrical portion (first outer cylindrical portion) 52 that covers the inner cylindrical portion 51, and a plurality of ribs (first ribs) 53 that integrally connect the inner cylindrical portion 51 and the outer cylindrical portion 52. The first pump casing 41 has a plurality of openings 54 that are formed by a portion of the outer peripheral surface of the inner cylindrical portion 51, a portion of the inner peripheral surface of the outer cylindrical portion 52, and circumferentially opposing surfaces of two adjacent ribs 53. The plurality of openings 54 are provided at equal intervals.

[0026] As shown in Figure 3, the first pump casing 41 has a storage section 41a that stores the first impeller 42 therein, a return flow path 41b formed from the outer periphery of the first pump casing 41 toward the center of the storage section 41a, and guide vanes 41c arranged in the storage section 41a of the first pump casing 41 connected to the primary side.

[0027] The return flow passage 41b has a plurality of return vanes 41d that guide water to the suction port of the secondary-side first pump casing 41. The return flow passage 41b forms a water flow that is continuous with the storage section 41a of the secondary-side first pump casing 41 or the storage section 41a of the central casing 34.

[0028] The first pump casing 41 is formed so as to be connectable to the first pump casing 41, the central casing 34, and the flow path cover 31 that are adjacent to it in the vertical direction.

[0029] For example, as shown in FIG. 3, 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.

[0030] 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 inner diameter of the engaged portion 52b, and the engaging portion 52a is inserted into the engaged portion 52b.

[0031] The first pump casing 41 also has an opening separated from the first impeller 42 by a predetermined gap, and an opening in which the pump main shaft 22 is disposed, and a liner ring 41e is provided on the inner peripheral edge of the opening facing the first impeller 42. Furthermore, an underwater bearing 41f is disposed in one of the openings of the multiple first pump casings 41.

[0032] The lowest first pump casing 41 has a plurality of holes 44 for inserting the temporary assembly bolts 37. For example, the holes 44 are provided on the outer peripheral surface of the first pump casing 41. As a specific example, the plurality of holes 44 are provided at symmetrical positions on the outer peripheral surface of the first pump casing 41, and in this embodiment, two holes 44 are provided.

[0033] The first impeller 42 is made of, for example, stainless steel or resin. As shown in Fig. 2, the first impeller 42 has a discharge port 42a provided on the outer periphery of the first impeller 42 and a suction port 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 port 42b facing downward in the axial direction. For example, the first impeller 42 has a pair of shrouds, and the outer peripheries of the pair of shrouds form the discharge port 42a, and the suction port 42b is formed in the center of one of the shrouds.

[0034] As shown in Fig. 2, the first partition plate 43 is provided between the flow path cover 31 and the first pump casing 41, between adjacent first pump casings 41, and between the first pump casing 41 and the central casing 34. The first partition plate 43 separates the adjacent casings 34, 41 and the flow path cover 31, and forms an accommodation space between the first partition plate 43 and the opposing first pump casing 41 to accommodate the first impeller 42. As shown in Fig. 5, the first partition plate 43 is disposed opposite the shroud in which the suction port 42b of the first impeller 42 is formed. The first partition plate 43 includes a first plate portion 43a and a plurality of guide vanes 43b provided on one main surface of the first plate portion 43a.

[0035] An opening where the suction port 42b of the first impeller 42 is disposed is formed on the central side of the first plate portion 43a. The surface of the first plate portion 43a that faces the shroud of the first impeller 42 is formed in a shape that follows the outer surface of the shroud. Note that, when a portion of the surface of the first plate portion 43a that faces the shroud of the first impeller 42 on the central side faces the first impeller 42, a portion of the first plate portion 43a that is radially outward from the portion that faces the first impeller 42 is formed flat, for example, along a radial direction perpendicular to the axial direction of the main shaft 12. Furthermore, a plurality of guide vanes 43b are formed integrally on a surface of the first plate portion 43a opposite the surface that faces the first impeller 42 in the axial direction of the main shaft 12. For example, the surface of the first plate portion 43a on which the multiple guide vanes 43b are provided (i.e., the surface opposite to the surface facing the first impeller 42) is formed flat along the radial direction (horizontal direction) perpendicular to the axial direction of the main shaft 12, or is inclined so that the thickness of the first plate portion 43a decreases from the outer peripheral edge side toward the center side in the radial direction.

[0036] Therefore, when the surface of the first plate portion 43a on which the guide vanes 43b are provided faces upward in the direction of gravity, the upper surface of the first plate portion 43a is flat along the horizontal direction or slopes, and does not include any portion with a reverse slope. Furthermore, when the surface of the first plate portion 43a on which the guide vanes 43b are provided faces downward in the direction of gravity, the upper surface of the first plate portion 43a is flat along the horizontal direction on the radially outer side, and slopes along the inclined surface of the first impeller 42 on the radially central side, which faces the first impeller 42. In this embodiment, when the pump device 1 is oriented such that the main shaft 12 faces the direction of gravity, the suction port 42b of the first impeller 42 faces downward, and the surface of the first plate portion 43a on which the guide vanes 43b are provided faces downward in the direction of gravity.

[0037] The guide vanes 43b guide water from the primary side to the suction port 42b of the first impeller 42 arranged at the opening of the first plate portion 43a. For example, the guide vanes 43b of the first partition plate 43 provided between adjacent first pump casings 41 face the return vanes 41d of the first pump casing 41 and form a return flow path 41b together with the return vanes 41d.

[0038] The first pump group 32A has a plurality of first pump casings 41 and a central casing 34 stacked together to form a first casing flow path 32a in which a plurality of openings 54 are axially connected. The first pump group 32A also has a flow path cover 31, a plurality of first pump casings 41, and a central casing 34 stacked together, with first partition plates 43 interposed between the flow path cover 31 and the first pump casings 41, between adjacent first pump casings 41, and between the first pump casings 41 and the central casing 34. The first pump group 32A has a plurality of inner cylindrical portions 51 within which a flow path for water whose pressure is increased by a plurality of first impellers 42 is formed, which is continuous with the first casing flow path 32a.

[0039] The second pump group 33A is formed by stacking multiple second pump units 33. The second pump units 33 pump water sucked in from above downward. The second pump units 33 are configured to be able to pump water sucked in from above downward. The second pump units 33 include a second pump casing 61, a second impeller 62 fixed to the pump main shaft 22 and housed in the second pump casing 61, and a second partition plate 63. As shown in FIG. 3 , the second pump casing 61 has the same configuration as the first pump casing 41. That is, compared to the first pump unit 32, the second pump unit 33 has the second pump casing 61 and the second impeller 62 arranged in the opposite direction relative to the first pump casing 41 and the first impeller 42, thereby setting the water pumping direction in the opposite direction. Therefore, in the multi-stage first pump group 32A, the lowest stage in the water flow direction is the primary side and the highest stage is the secondary side, and in the multi-stage second pump group 33A, the highest stage in the water flow direction is the primary side and the lowest stage is the secondary side.

[0040] As shown in FIG. 3 , the second pump casing 61 includes an inner cylindrical portion (second inner cylindrical portion) 71, an outer cylindrical portion (second outer cylindrical portion) 72 that covers the inner cylindrical portion 71, and a plurality of ribs (second ribs) 73 that integrally connect the inner cylindrical portion 71 and the outer cylindrical portion 72. The second pump casing 61 has a plurality of openings 74 formed by a portion of the outer peripheral surface of the inner cylindrical portion 71, a portion of the inner peripheral surface of the outer cylindrical 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. Therefore, the second pump casing 61 will be described using the same drawings. However, because the orientation of the impeller (second impeller 62) housed in the second pump casing 61 is different from that of the first pump casing 41, the detailed shape and the positional relationship of each component differ even though the second pump casing 61 and the first pump casing 41 have the same configuration.

[0041] As shown in Figure 3, the second pump casing 61 has a storage section 61a that stores the second impeller 62 therein, a return flow path 61b formed from the outer periphery of the second pump casing 61 toward the center of the storage section 61a, and a guide vane 61c arranged in the storage section 61a of the second pump casing 61 connected to the primary side.

[0042] The return flow passage 61b has a plurality of return vanes 61d that guide water to the suction port of the secondary-side second pump casing 61. The return flow passage 61b forms a water flow that is continuous with the storage section 61a of the secondary-side second pump casing 61 or the storage section 61a of the central casing 34.

[0043] The second pump casing 61 is formed so as to be connectable to the second pump casing 61 and the central casing 34 adjacent thereto in the vertical direction.

[0044] For example, as shown in FIG. 3, 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.

[0045] 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.

[0046] The second pump casing 61 also has an opening separated from the second impeller 62 by a predetermined gap, and an opening in which the pump main shaft 22 is disposed, and a liner ring 61e is provided on the inner peripheral edge of the opening facing the second impeller 62.

[0047] The second impeller 62 is made of, for example, stainless steel or resin. As shown in Figures 1 and 2, the second impeller 62 has a discharge port 62a provided on the outer periphery of the second impeller 62 and a suction port 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 port 62b facing upward in the axial direction. For example, the second impeller 62 has a pair of shrouds, and the outer peripheries of the pair of shrouds form the discharge port 62a, and the suction port 62b is formed in the center of one of the shrouds.

[0048] As shown in Fig. 2, the second partition plates 63 are provided between adjacent second pump casings 61, between the second pump casing 61 and the central casing 34, and between the second pump casing 61 and the casing cover 35. The second partition plates 63 separate the adjacent casings 34, 61 and the casing cover 35, and form an accommodation space between the opposing second pump casing 61 to accommodate the second impeller 62. As shown in Fig. 5, the second partition plate 63 is disposed opposite the shroud in which the suction port 62b of the second impeller 62 is formed. The second partition plate 63 includes a second plate portion 63a and a plurality of guide vanes 63b provided on one main surface of the second plate portion 63a.

[0049] An opening in which suction port 62b of second impeller 62 is disposed is formed on the central side of second plate portion 63a. A surface of second plate portion 63a facing the shroud of second impeller 62 is formed in a shape that follows the outer surface of the shroud. Note that when a part of the inner center side of the surface of second plate portion 63a facing the shroud of second impeller 62 faces second impeller 62, a part of second plate portion 63a radially outward from the part facing second impeller 62 is formed flat along, for example, a radial direction perpendicular to the axial direction of main shaft 12. Further, a plurality of guide vanes 63b are formed integrally on a surface of second plate portion 63a opposite to the surface facing second impeller 62 in the axial direction of main shaft 12. For example, the surface of the second plate portion 63a on which the multiple guide vanes 63b are provided (i.e., the surface opposite to the surface facing the second impeller 62) is formed flat along the radial direction perpendicular to the axial direction of the main shaft 12, or is inclined so that the thickness of the second plate portion 63a decreases from the outer peripheral edge side toward the center side in the radial direction.

[0050] Therefore, when the surface of the second plate portion 63a on which the guide vanes 63b are provided faces upward in the direction of gravity, the upper surface of the second plate portion 63a is flat or sloped in the horizontal direction, and does not include any portion with a reverse slope. In this embodiment, when the pump device 1 is in an orientation in which the main shaft 12 faces the direction of gravity, the suction port 62b of the second impeller 62 faces upward, so the upper surface of the second plate portion 63a extends in the horizontal direction or slopes. When water is drained from the pump 13, water does not accumulate on the second plate portion 63a but moves downward in the direction of gravity. In other words, the upper surface of the second plate portion 63a does not have a reverse slope, which would cause water to accumulate without naturally draining in the direction of gravity.

[0051] The guide vanes 63b guide water from the primary side to the suction port 62b of the second impeller 62 disposed at the opening of the second plate portion 63a. For example, the guide vanes 63b of the second partition plate 63 provided between adjacent second pump casings 61 face the return vanes 61d of the second pump casing 61 and form a return flow path 61b together with the return vanes 61d.

[0052] Next, a specific example of the configuration of the second plate portion 63a, which is a component that is provided inside the inner cylinder 71 of the pump casing 61 of the second pump group 33A and does not have a reverse gradient, will be described with reference to FIG.

[0053] For example, second impeller 62 includes first shroud 621, second shroud 622, and a plurality of blades 623. First shroud 621 is formed in a disk shape, and has a boss at its center that is fixed to main shaft 12. Second shroud 622 is disposed opposite first shroud 621 with a predetermined gap therebetween in the axial direction. Second shroud 622 has suction port 62b formed on its central side. Second shroud 622 also has at least a sloped portion 622a that slopes from the outer circumferential edge side toward suction port 62b side, away from first shroud 621.

[0054] The plurality of blades 623 are arranged at equal intervals in the circumferential direction of the second impeller 62. The plurality of blades 623 are integrally fixed to the first shroud 621 and the second shroud 622 by welding or the like.

[0055] In the second impeller 62, the outer circumferential edges of the first shroud 621 and the second shroud 622 form a discharge port 62a.

[0056] The second plate portion 63a of the second partition plate 63 is formed in an annular plate shape and has a facing portion 63c facing the second shroud 622. The facing portion 63c is formed in a shape that allows it to face the second shroud 622 with a predetermined gap therebetween. As a specific example, the surface of the facing portion 63c facing the inclined portion 622a is inclined at the same inclination angle as or an approximate inclination angle to the inclination of the inclined portion 622a.

[0057] 4, in the axial direction of main shaft 12, the dimension from the end of suction port 62b of second shroud 622 to the lower end of the surface (the surface on which multiple blades 623 are provided) facing first shroud 621 is defined as H1, and the maximum dimension (thickness) of second plate portion 63a is defined as H2. In this case, thickness H2 of second plate portion 63a is set to be, for example, equal to or greater than dimension H1 from the end of first shroud 621 to the lower end of the surface facing first shroud 621 (H1≦H2).

[0058] In this way, since dimension H2 is greater than or equal to dimension H1, the upper surface of the second partition plate 63 is higher than the suction port 62b of the second impeller 62, and therefore, when the pump device 1 is operating, water flows smoothly from the upper surface of the second partition plate 63 to the suction port 62b of the second impeller 62.

[0059] The liner ring 61e is formed, for example, in an annular shape with a rectangular cross section. As shown in Fig. 4, the liner ring 61e is disposed, for example, in a stepped portion 63d on the inner peripheral edge portion of the opposing portion 63c of the second partition plate 63, and faces the outer periphery of the cylindrical portion forming the suction port 62b of the second shroud 622 of the second impeller 62. As a specific example, the liner ring 61e is fixed by a stopper 61f that fits into the stepped portion 63d of the second partition plate 63. The stopper 61f is formed, for example, in an annular shape with an L-shaped cross section, and the horizontally extending wall surface of the stopper 61f sandwiches the liner ring 61e with the stepped portion 63d in the axial direction, and the axially extending wall surface of the stopper 61f fits into the stepped portion 63d and sandwiches the liner ring 61e in the horizontal direction, thereby fixing the liner ring 61e to the stepped portion 63d. For example, a minute gap is formed between the outer circumferential surface of the cylindrical portion that forms the suction port 62b of the second impeller 62 and the inner circumferential surface of the liner ring 61e.

[0060] The second pump group 33A has a plurality of second pump casings 61 and a central casing 34 stacked together to form a second casing flow path 33a in which a plurality of openings 54 are axially connected. The second pump group 33A also has a central casing 34, a plurality of second pump casings 61, and a casing cover 35 stacked together, with second partition plates 63 interposed between the central casing 34 and the second pump casings 61, between adjacent second pump casings 61, and between the second pump casings 61 and the casing cover 35. The second pump group 33A has a plurality of inner cylindrical portions 71 within which flow paths for water pressurized by a plurality of second impellers 62 are formed, which are continuous with the second casing flow path 33a.

[0061] 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, and the first pump group 32A and the second pump group 33A may have different design values such as blade diameter and suction diameter.

[0062] 6, the central casing 34 includes an inner cylindrical portion (third inner cylindrical portion) 81, an outer cylindrical portion (third outer cylindrical portion) 82 that covers the inner cylindrical portion 81, and a plurality of ribs (third ribs) 83 that integrally connect the inner cylindrical portion 81 and the outer cylindrical portion 82. The central casing 34 is connected to the uppermost first pump portion 32 and the lowermost second pump portion 33. 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.

[0063] The central casing 34 houses the first impeller 42 and the second impeller 62. The central casing 34 also defines an ascending flow path 34a that guides water pressure-fed upward from the housed first impeller 42 to the second casing flow path 33a, and a descending flow path 34b that guides water pressure-fed downward from the housed second impeller 62 to the first casing flow path 32a.

[0064] The inner cylindrical portion 81 has a plate portion 81a that defines the center in the axial direction. The inner cylindrical portion 81 has a storage portion 41a that houses the first impeller 42 and is provided on the lower side defined by the plate portion 81a, and a storage portion 61a that houses the second impeller 62 and is provided on the upper side. In other words, the central casing 34 constitutes a part of the first pump portion 32 and a part of the second pump portion 33. In addition, a cylindrical liner ring portion is provided in the center of the plate portion 81a, facing a sleeve provided on the pump main shaft 22 with a small gap between them.

[0065] 2, an underwater bearing 81b is provided on the liner ring portion of the plate portion 81a. The underwater bearing 81b is inserted, for example, from the high-pressure side to the low-pressure side of the first pump group 32A or the second pump group 33A.

[0066] The outer cylindrical portion 82 is integrally connected to the inner cylindrical portion 81 by a plurality of ribs 83. The plurality of ribs 83 are formed at the same positions and in the same number as those of the first pump casing 41 and the second pump casing 61. The outer cylindrical portion 82 has a plurality of openings 91 that are defined by the plate portion 81a of the inner cylindrical portion 81 and the plurality of ribs 83 and communicate with the upper and lower sides of the inner cylindrical 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.

[0067] The outer tube 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 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 engaged portion 72b of the adjacent second pump casing 61.

[0068] The engaging portion 82a and the engaged portion 82b are formed so that one can be inserted into the other. For example, the outer diameter of the engaging portion 82a is formed to be the same as the inner diameter of the engaged portion 82b or slightly smaller than the inner diameter of the engaged portion 82b, and the engaging portion 82a is inserted into the engaged portion 82b.

[0069] Each of the plurality of openings 91 includes a first opening 91a and a second opening 91b formed by dividing the opening 91 into two in the circumferential direction.

[0070] The first opening 91a is open to the inner circumferential surface of the inner tubular portion 81 at a lower side of the inner tubular portion 81 defined by the plate portion 81a, and is closed off from the inner circumferential surface of the inner tubular portion 81 at an upper side. The first opening 91a is continuous with the storage portion 41a at its lower side that opens to the inner circumferential surface of the inner tubular portion 81, and is closed off from the inner circumferential surface of the inner tubular portion 81 at its upper side that is continuous to the opening 74 of the second pump casing 61.

[0071] The second opening 91b is open to the inner circumferential surface of the inner cylindrical portion 81 at an upper side thereof defined by the plate portion 81a, and is closed off from the inner circumferential surface of the inner cylindrical portion 81 at a lower side thereof. The second opening 91b is continuous with the storage portion 61a at an upper side thereof that opens to the inner circumferential surface of the inner cylindrical portion 81, and is closed off from the inner circumferential surface of the inner cylindrical portion 81 at a lower side thereof that is continuous with the opening 54 of the first pump casing 41.

[0072] The central casing 34 also includes guide vanes 92 arranged in the storage portions 41a and 61a. The guide vanes 92 guide the water discharged from the first impeller 42 and the second impeller 62 from the storage portions 41a and 61a to the first opening 91a and the second opening 91b.

[0073] In the central casing 34, the storage section 41a of the inner cylindrical portion 81 and the multiple first openings 91a form an ascending flow path 34a that connects the secondary side of the first pump group 32A and the second casing flow path 33a of the second pump group 33A. In addition, the storage section 61a of the inner cylindrical portion 81 and the multiple second openings 91b form a descending flow path 34b that connects the secondary side of the second pump group 33A and the first casing flow path 32a of the first pump group 32A.

[0074] The casing cover 35 covers the uppermost second pump casing 61. The casing cover 35 forms a flow path that guides water pumped from the suction port 31a of the flow path cover 31 through the first impeller 42, via the ascending flow path 34a of the central casing 34 and the second casing flow path 33a, to the second impeller 62 of the uppermost second pump section 33. As shown in FIG. 2, the casing cover 35 has, for example, a flange portion 35a. As shown in FIG. 2, the flange portion 35a has first hole portions 35b into which temporary assembly bolts 37 are inserted and second hole portions 35c into which main bolts 38 are inserted.

[0075] The first hole portions 35b are formed so as to be able to fix the temporary assembly bolts 37. For example, the first hole portions 35b have female threads formed on the inner peripheral surfaces thereof. The first hole portions 35b are provided in the same number as the temporary assembly bolts 37 and are arranged at symmetrical positions.

[0076] The number of second holes 35c provided is the same as the number of main bolts 38. The second holes 35c are, for example, arranged symmetrically with respect to the axis of the flange portion 35a.

[0077] The seal members 36 are, for example, O-rings. The seal members 36 are compressed between the components to prevent water from leaking between the components. Specific examples of the seal members 36 include those provided 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.

[0078] The pre-assembled bolt 37 has, for example, male threaded portions 37a formed on both ends, one end of which is fixed by screwing into the first hole portion 35b of the casing cover 35, and the other end of which is inserted into the hole portion 44 of the lowest first pump casing 41 and screwed into the nut 37b.

[0079] The temporary assembly bolts 37 are fastened to the first holes 35b and the nuts 37b to press and secure, for example, at least the first pump casings 41, the central casing 34, and the second pump casings 61, which are central casings constituting the pump 13, toward each other. In this embodiment, the temporary assembly bolts 37 secure, for example, the first pump casings 41, the central casing 34, the second pump casings 61, and the casing cover 35. The temporary assembly bolts 37 have a length from the lowest first pump casing 41 to the first holes 35b in the flange portion 35a of the casing cover 35. Note that the temporary assembly bolts 37 are used to temporarily secure the components as a temporary assembly when assembling the pump 13. However, the pump device 1 may be configured without the temporary assembly bolts 37 as long as the pump 13 can be assembled and secured.

[0080] The number of main bolts 38 provided is greater than the number of temporary assembly bolts 37. The main bolts 38 have an outer diameter that is equal to or larger than the outer diameter of the temporary assembly bolts 37.

[0081] The main bolt 38 has, for example, male threaded portions 38a formed on both ends, one end of which is threaded into the fixed portion 31d of the base 31c of the flow path cover 31, and the other end of which is inserted into the second hole portion 35c of the casing cover 35 and threaded into a nut 38b.

[0082] The main bolt 38 has a length, for example, from the base 31c of the flow path cover 31 to the second hole 35c of the flange portion 35a of the casing cover 35. When the main bolt 38 is fastened to the second hole 35c and the nut 38b, the flow path cover 31, the plurality of first pump casings 41, the central casing 34, the plurality of second pump casings 61, and the casing cover 35 are pressed toward each other and fixed in place.

[0083] In the pump device 1 configured in this manner, at least the surfaces of the first pump section 32 and the second pump section 33 that become the upper surfaces during drainage are either flat and extend horizontally, or sloped to allow natural drainage. As a result, when the main shaft 12 of the pump device 1 is oriented in the direction of gravity, a reverse gradient that prevents natural drainage and causes water to accumulate is not formed inside the first pump section 32 and the second pump section 33. Therefore, the pump device 1 that drains water with the main shaft 12 oriented in the direction of gravity can prevent water from remaining inside, thereby suppressing leakage of residual water from the pump device 1 after shipment. Furthermore, the pump device 1 does not need to be oriented diagonally or sideways to promote drainage of residual water, and water can be easily drained while upright, making the draining process easier.

[0084] Furthermore, by configuring the first pump section 32 and the second pump section 33 so that they do not have a reverse gradient shape, the shape of the flow channel can be prevented from becoming uneven, thereby reducing the flow resistance of the flow channel from the inner tube sections 51, 71 in the first pump group 32A and the second pump group 33A to the outer tube sections 52, 72.

[0085] In addition, since the second plate portion 63a has an inclined surface facing the inclined portion 622a formed on the second shroud 622 of the second impeller 62, the gap with the second impeller 62 can be reduced without the upper surface having a reverse slope, which makes it possible to reduce disc friction loss, which is energy loss caused by vortices that occur in the gap with the second impeller 62.

[0086] Furthermore, by making the second partition plate 63 separate from the second casing 61, even if the second plate portion 63a of the second partition plate 63 is thick, it is less likely that voids will form during molding, and even if voids do form, it is possible to prevent water from leaking from the inner cylindrical portion 71 to the external second casing flow path 33a, for example.

[0087] As described above, according to the pump device 1 of one embodiment of the present invention, when the direction along the rotation center of the impeller 42, 62 is the direction of gravity, the upper surfaces of the partition plates 43, 63, which are components within the casing 41, 61, are shaped so as not to include a reverse slope, thereby preventing residual water from being generated after draining.

[0088] The present invention is not limited to the above-described embodiment. For example, to achieve a self-balancing pump device 1, a configuration has been described in which the multiple impellers include a first impeller 42 and multiple second impellers 62 arranged in different directions, but the present invention is not limited to this. For example, the pump device 1 may be configured such that the multiple impellers are arranged in the same direction. Furthermore, in the above example, the pump device 1 is an example of a vertical pump, but the present invention is not limited to this and can be applied to a pump in which the extension direction of the main shaft, i.e., the direction along the center of rotation of the impeller, is aligned with the direction of gravity when draining water.

[0089] In addition, in the above example, the second impeller 62 and second partition plate 63 of the second pump section 33 were explained using Figure 4, but since the above-mentioned first pump section 32 has a configuration similar to that of the second pump section 33, but the orientations of the impellers 42, 62 are different, Figure 4 and the above explanation can be read as an explanation of the first pump section 32.

[0090] The present invention is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the spirit of the invention. Furthermore, the embodiments may be implemented in appropriate combinations, in which case the combined effects can be obtained. Furthermore, the above-described embodiments include various inventions, and various inventions can be extracted by combining selected elements from the disclosed elements. For example, if the problem can be solved and the desired effect can be obtained even if some elements are deleted from all elements shown in the embodiments, the configuration from which these elements are deleted can be extracted as an invention. [Explanation of symbols]

[0091] 1...pump device, 11...motor, 12...main shaft, 11a...motor casing, 12...main shaft, 13...pump, 21...motor main shaft, 22...pump main shaft, 22a...mechanical seal, 23...shaft coupling, 31...flow path cover, 31a...suction port, 31b...discharge port, 31c...base, 31d...fixing part, 32A...first pump group, 32...first pump section, 32a...first casing flow path, 33A...second pump group, 33...second pump section, 33a...second casing flow path, 34...central casing (casing), 34a...upward flow path, 34b...downward flow path, 35...casing cover, 35a...flange portion, 35b...first hole portion, 35c...second hole portion, 36...sealing member, 37...temporarily assembled bolt, 37a...male thread portion, 37b...nut, 38...main bolt, 38a...male thread portion, 38b...nut, 40...sealing member, 41...first pump casing (casing), 41a...storage portion, 41b...flow path, 41c...guide vane, 41d...vane, 41e...liner ring, 41f...underwater bearing, 42...first impeller (impeller), 42a...discharge port, 42b...suction port, 4 3...first partition plate, 44...hole portion, 51...inner cylinder portion (first inner cylinder portion), 52...outer cylinder portion (first outer cylinder portion), 52a...engaging portion (first engaging portion), 52b...engaged portion (first engaged portion), 53...rib (first rib), 54...opening, 61...second pump casing (casing), 61a...storage portion, 61b...flow path, 61c...guide vane, 61d...vane, 61e...liner ring, 61f...stop plate, 62...second impeller (impeller), 62a...discharge port, 62b...suction port, 63...second partition plate, 63a...second plate portion, 63b...guide vane, 63c...opposing portion, 63d...step portion, 71...inner cylinder portion (second inner cylinder portion), 72...outer cylinder portion (second outer cylinder portion), 72a...engaging portion (second engaging portion), 72b...engaged portion (second engaged portion), 73...rib (second rib), 74...opening, 81...inner cylinder portion (third inner cylinder portion), 81a...plate portion, 81b...underwater bearing, 82...outer cylinder portion (third outer cylinder portion), 82a...engaging portion (third engaging portion), 82b...engaged portion (third engaged portion), 83...rib (third rib), 91...opening, 91a...first opening, 91b...second opening, 92...guide vane, G1...installation surface.

Claims

1. a shroud having an inclined portion inclined relative to a rotation center formed therein, and a plurality of impellers having a plurality of blades provided on the shroud; a plurality of casings stacked one on top of the other, each casing housing the impeller; a partition plate provided between adjacent casings, the partition plate having an inclined surface facing the inclined portion; Equipped with A pump device in which, when the center of rotation of the impeller is aligned with the direction of gravity, the upper surface of the partition plate is formed flat or sloped and does not include a reverse slope that prevents natural drainage in the direction of gravity.

2. The casing and the partition plate are formed separately, The pump device according to claim 1 , wherein the partition plate has an annular plate portion and a plurality of guide vanes.

3. 3. The pump device according to claim 1, wherein the plurality of impellers includes a plurality of first impellers and a plurality of second impellers arranged in a direction different from that of the first impellers.

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