Pump device

Abstract

To provide a pump device capable of suppressing the residual of water after drain.SOLUTION: A pump device 1 includes a plurality of impellers 42, 62, and a plurality of casings 34, 41, 61 mutually laminated and having inner cylinder parts 51, 71, 81 storing the impellers 42, 62, outer cylinder parts 52, 72, 82 forming flow paths in spaces from the inner cylinder parts 51, 71, 81, and a plurality of ribs 53, 73, 83 formed between the inner cylinder parts 51, 71, 81 and the outer cylinder parts 52, 72, 82, respectively. In the casings 34, 41, 61 in the inner cylinder parts 51, 71, 81 of which reverse gradients are generated, a drain hole 39 is formed connecting the inner cylinder parts 51, 71, 81 and the outside.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] As a pump device for supplying water to super high-rise buildings, tower mansions, etc., a multistage pump having a plurality of impellers and a casing is known. Such a pump device, for example, has a double cylindrical casing, accommodates an impeller in the inner cylinder part, and forms a flow path through which water that has passed through a plurality of impellers flows between the inner cylinder part and the outer cylinder part (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Such a pump device, for example, is subjected to a performance test by passing water before shipment and then shipped after draining the water. However, if there is a portion with a reverse gradient such as a depression in the flowing water path formed inside the pump device, the drainage performance is poor and residual water may be generated. For this reason, even if the posture of the pump device is changed to a posture in which the axial direction of the rotating shaft is the gravity direction or a horizontal direction, the water may not drain. For this reason, there is a risk of water leakage during movement or installation after shipment. For this reason, there is a demand for a pump device capable of reducing residual water after draining.

[0005] Therefore, an object of the present invention is to provide a pump device capable of suppressing residual water after draining.

Means for Solving the Problems

[0006] According to one aspect of the present invention, a pump device includes a plurality of impellers, an inner cylinder portion that houses the impellers, an outer cylinder portion that forms a flow path between the inner cylinder portion, and a plurality of casings that are stacked on each other and have a plurality of ribs formed between the inner cylinder portion and the outer cylinder portion. A drain hole that connects the inner cylinder portion and the outside is formed in the casing where an inverse gradient occurs in the inner cylinder portion.

Effect of the Invention

[0007] According to the present invention, it is possible to provide a pump device that can suppress residual water after draining.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0009] Hereinafter, the configuration of a pump device 1 according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 6.

[0010] FIG. 1 is a schematic view showing a configuration of a pump device 1 according to an embodiment of the present invention in a partial cross section. FIG. 2 is a schematic view showing a configuration of the pump device 1 in a partial cross section from a direction rotated 90° around the rotation center of the main shaft 12. FIG. 3 is a plan view showing a configuration of a first pump casing 41 and a second pump casing 61 used in the pump device 1 in a partial cross section, and FIG. 4 is an explanatory view schematically showing a configuration of streamlined ribs 53, 73, 83 in the casings 34, 41, 61 where drain holes 39 are formed. FIG. 5 is a perspective view showing a configuration of partition plates 43, 63 used in the pump device 1 with a part omitted. FIG. 6 is a perspective view showing a configuration of a central casing 34 used in the pump device 1 with a part omitted.

[0011] As shown in FIGS. 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 vertical multi-stage pump in which the main shaft 12 extends in the gravitational direction.

[0012] As shown in FIGS. 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.

[0013] 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.

[0014] As shown in FIGS. 1 and 2, the main shaft 12 is configured to be rotatable by the motor 11. The main shaft 12 extends in the gravitational direction so as to be able to fix a plurality of impellers provided in the pump 13. The main shaft 12 is composed of, for example, a motor main shaft 21, a pump main shaft 22, and a shaft joint 23.

[0015] The pump main shaft 22 is disposed in the pump 13. The pump main shaft 22 is formed so as to be able to fix a plurality of impellers 42, 62 provided in the pump 13. The pump main shaft 22 is a part of the components of the pump 13.

[0016] The shaft joint 23 connects the motor spindle 21 and the pump spindle 22 so that the pump spindle 22 can rotate as the motor spindle 21 rotates.

[0017] As shown in FIGS. 1 and 2, the pump 13 has a plurality of pump sections each having an impeller and a casing. Specifically, the pump 13 includes a pump spindle 22, a flow path cover 31 forming a suction port 31a and a discharge port 31b, a first pump group 32A forming an upward flow, a second pump group 33A disposed above the first pump group 32A and forming a downward flow, a central casing 34 provided between the first pump group 32A and the second pump group 33A, a casing cover 35, a seal member 36, temporary assembly bolts 37, and main bolts 38. Further, in the casings of the pump sections in which a reverse gradient portion is generated inside among the first pump group 32A and the second pump group 33A of the pump 13, drain holes 39 are formed and closed by a sealing member 40 such as a plug. Further, between the main shaft 12 and the casing cover 35 of the pump 13 described later, a mechanical seal 22a is provided which includes a rotating ring fixed to the main shaft 12 and a fixed ring fixed to the casing cover 35 and which can rotate and slide and seals the gap between the main shaft 12.

[0018] As shown in FIG. 1, when the pump device 1 is installed on the installation surface G1 so as to be the vertical axis, the flow path cover 31 is located at the lowermost 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 lowermost first pump section 32. The discharge port 31b of the flow path cover 31 forms a flow path continuous with a first casing flow path 32a of the first pump group 32A described later. The suction port 31a and the discharge port 31b are provided at symmetric positions around the rotation center of the main shaft 12, that is, at intervals of 180°.

[0019] In addition, 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 portion 31d is a hole formed in the base 31c. The fixing portion 31d is arranged on the base 31c avoiding the suction port 31a and the discharge port 31b. The number of fixing portions 31d provided is the same as the number of main bolts 38. The plurality of fixing portions 31d are symmetrically arranged. As a specific example, the plurality of fixing portions 31d are, for example, equally spaced around an axis, or sets of the plurality of fixing portions 31d are arranged at symmetrical positions. The fixing portion 31d is a hole or the like capable of fixing the main bolt 38.

[0020] For example, the main bolt 38 has a male screw portion at its end, the fixing portion 31d has a female screw portion, and the main bolt 38 is screwed into the fixing portion 31d, so that the fixing portion 31d fixes the main bolt 38. Note that the fixing of the fixing portion 31d and the main bolt 38 may be configured such that the end of the main bolt 38 is press-fitted, or a head portion may be provided on the main bolt 38 and the fixing portion 31d may have a seat for receiving this head portion, or the end of the main bolt 38 may be configured as a rectangular column, and the fixing portion 31d may be a rectangular columnar bottomed hole to restrict the movement of the main bolt 38 in the axial direction and the circumferential direction.

[0021] In the first pump group 32A and the second pump group 33A, the housed impellers 42 and 62 are arranged in opposite directions to each other, so that the water pumping directions are set in opposite directions in the axial direction. That is, in the first pump group 32A, the water flow direction is upward, and in the second pump group 33A, the water flow direction is downward. The pump device 1 having such a first pump group 32A and a second pump group 33A is a so-called self-balancing type pump capable of reducing the thrust load.

[0022] The first pump group 32A is configured by stacking a plurality of first pump units 32. The first pump unit 32 pumps the water sucked from below upward. The first pump unit 32 includes 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.

[0023] As shown in FIG. 3, the first pump casing 41 includes an inner cylinder part (first inner cylinder part) 51, an outer cylinder part (first outer cylinder part) 52 that covers the inner cylinder part 51, and a plurality of ribs (first ribs) 53 that integrally connect the inner cylinder part 51 and the outer cylinder part 52. The first pump casing 41 has a plurality of openings 54 formed by a part of the outer peripheral surface of the inner cylinder part 51, a part of the inner peripheral surface of the outer cylinder part 52, and the surfaces facing each other in the circumferential direction of two adjacent ribs 53. The plurality of openings 54 are provided at equal intervals.

[0024] As shown in FIG. 3, the first pump casing 41 includes a storage part 41a that houses the first impeller 42 inside, a return flow path 41b formed from the outer peripheral side to the center side of the first pump casing 41 toward the storage part 41a, and a guide vane 41c disposed in the storage part 41a of the first pump casing 41 connected to the primary side.

[0025] The return flow path 41b has a plurality of return vanes 41d that guide water to the suction port of the first pump casing 41 on the secondary side. The return flow path 41b forms a continuous water flow that is continuous with the storage part 41a of the first pump casing 41 on the secondary side or the storage part 41a of the central casing 34.

[0026] Further, 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 each other vertically.

[0027] For example, as shown in FIG. 3, the outer cylinder part 52 of the first pump casing 41 has an engaging part (first engaging part) 52a at the upper end or the lower end, and a part to be engaged (first part to be engaged) 52b that engages with the engaging part 52a at the lower end or the upper end.

[0028] The engaging part 52a and the part to be engaged 52b are formed such that one can be inserted into the other. For example, the outer diameter of the engaging part 52a is the same as the inner diameter of the part to be engaged 52b, or is formed to be slightly smaller than the part to be engaged 52b, and the engaging part 52a is inserted into the part to be engaged 52b.

[0029] Further, the first pump casing 41 includes an opening spaced apart from the first impeller 42 by a predetermined gap and an opening in which the pump main shaft 22 is disposed. A liner 41e is provided at the inner peripheral edge of the opening facing the first impeller 42. Also, a water bearing 41f is disposed in an opening of any one of the plurality of first pump casings 41.

[0030] The lowermost first pump casing 41 has a plurality of holes 44 for inserting 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 symmetric positions on the outer peripheral surface of the first pump casing 41, and in this embodiment, two holes 44 are provided.

[0031] The first impeller 42 is formed of, for example, stainless steel, resin, or the like. As shown in FIG. 2, the first impeller 42 includes a discharge portion 42a provided on the outer peripheral side of the first impeller 42 and a suction portion 42b provided on one main surface side of the first impeller 42. The first impeller 42 is housed in the first pump casing 41 with the suction portion 42b facing downward in the axial direction. For example, the first impeller 42 has a pair of shrouds, and the outer peripheral edges of the pair of shrouds form the discharge portion 42a, and the suction portion 42b is formed at the center of one of the shrouds.

[0032] 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 partitions between the adjacent casings 34, 41 and the flow path cover 31, and forms an accommodation space for accommodating the first impeller 42 between the opposing first pump casings 41. Also, as shown in FIG. 5, the first partition plate 43 is disposed opposite to the shroud in which the suction portion 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.

[0033] The first plate portion 43a has an opening formed at the center thereof for disposing the suction portion 42b of the first impeller 42. The surface of the first plate portion 43a facing the shroud of the first impeller 42 is formed in a shape along the outer surface of the shroud. Further, on the surface of the first plate portion 43a opposite to the surface facing the first impeller 42 in the axial direction of the main shaft 12, a plurality of guide vanes 43b are integrally formed. For example, the surface of the first plate portion 43a where the plurality of guide vanes 43b are provided (i.e., the surface opposite to the surface facing the first impeller 42) has an outer peripheral edge and a central side protruding axially on the side opposite to the first impeller 42, and a concave portion 43c is formed between the adjacent guide vanes 43b, where the portion between the outer peripheral edge and the central side is recessed toward the first impeller 42 side.

[0034] Therefore, when the surface of the first plate portion 43a where the plurality of guide vanes 43b are provided is in an upward position in the gravitational direction, the concave portion 43c has an inverse gradient for water to accumulate. In this embodiment, in the posture where the main shaft 12 of the pump device 1 is in the gravitational direction, the suction portion 42b of the first impeller 42 faces downward, and the surface of the first plate portion 43a where the plurality of guide vanes 43b are provided is in a downward position in the weight direction. Therefore, when draining the water in the pump 13, water does not accumulate in the concave portion 43c.

[0035] The plurality of guide vanes 43b guide the water from the primary side to the suction portion 42b of the first impeller 42 disposed at the opening of the first plate portion 43a. For example, the plurality of guide vanes 43b of the first partition plate 43 provided between the adjacent first pump casings 41 face the plurality of return vanes 41d of the first pump casing 41, and together with the plurality of return vanes 41d, form a return flow path 41b.

[0036] The first pump group 32A constitutes a first casing flow path 32a in which a plurality of openings 54 communicate axially by laminating a plurality of first pump casings 41 and a central casing 34. Further, in the first pump group 32A, a flow path cover 31, a plurality of first pump casings 41, and a central casing 34 are laminated, and a first partition plate 43 is interposed 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. And in the first pump group 32A, a flow path for water pressurized by a plurality of first impellers 42 that is continuous with the first casing flow path 32a is formed in a plurality of inner cylinder portions 51.

[0037] The second pump group 33A is configured by laminating a plurality of second pump units 33. The second pump unit 33 pumps water sucked from above downward. The second pump unit 33 is configured to be able to pump water sucked from above downward. The second pump unit 33 includes 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. Here, as shown in FIG. 3, the second pump casing 61 has the same configuration as the first pump casing 41. That is, compared with 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 to the first pump casing 41 and the first impeller 42, so that the water pumping direction is set in the opposite direction. For this reason, in the multi-stage first pump group 32A, the lowermost stage in the water flow direction is the primary side and the uppermost stage is the secondary side, and in the multi-stage second pump group 33A, the uppermost stage in the water flow direction is the primary side and the lowermost stage is the secondary side.

[0038] As shown in FIG. 3, the second pump casing 61 includes an inner cylinder portion (second inner cylinder portion) 71, an outer cylinder portion (second outer cylinder portion) 72 that covers the inner cylinder portion 71, and a plurality of ribs (second ribs) 73 that integrally connect the inner cylinder portion 71 and the outer cylinder portion 72. The second pump casing 61 has a plurality of openings 74 formed by a part of the outer peripheral surface of the inner cylinder portion 71, a part of the inner peripheral surface of the outer cylinder portion 72, and the surfaces facing each other in the circumferential direction of two adjacent ribs 73. The plurality of openings 74 are provided at equal intervals. Note that the second pump casing 61 has the same configuration as the first pump casing 41. Therefore, the same drawing is used for explanation. However, since the direction of the impeller (second impeller 62) accommodated in the second pump casing 61 is different from that in the first pump casing 41, even though they have the same configuration, their detailed shapes and the positional relationships of the respective components are different.

[0039] As shown in FIG. 3, the second pump casing 61 includes a storage portion 61a that stores the second impeller 62 therein, a return flow path 61b formed from the outer peripheral side of the second pump casing 61 toward the center side of the storage portion 61a, and a guide vane 61c disposed in the storage portion 61a of the second pump casing 61 connected to the primary side.

[0040] The return flow path 61b has a plurality of return vanes 61d that guide water to the suction port of the second pump casing 61 on the secondary side. The return flow path 61b forms a continuous water flow that is continuous with the storage portion 61a of the second pump casing 61 on the secondary side or the storage portion 61a of the central casing 34.

[0041] Also, the second pump casing 61 is formed so as to be connectable to the second pump casing 61 and the central casing 34 adjacent to each other vertically.

[0042] For example, as shown in FIG. 3, the outer cylinder portion 72 of the second pump casing 61 has an engaging portion (second engaging portion) 72a at the upper end or the lower end, and a portion to be engaged (second portion to be engaged) 72b that engages with the engaging portion 72a at the lower end or the upper end.

[0043] The engaging portion 72a and the engaged portion 72b are formed such that one can be inserted into the other. For example, the outer diameter of the engaging portion 72a is the same as the inner diameter of the engaged portion 72b or slightly smaller than the inner diameter of the engaged portion 72b, and the engaging portion 72a is inserted into the engaged portion 72b.

[0044] Further, the second pump casing 61 includes an opening spaced apart from the second impeller 62 by a predetermined gap and an opening in which the pump main shaft 22 is disposed. A liner 61e is provided at the inner peripheral edge of the opening facing the second impeller 62.

[0045] The second impeller 62 is formed of, for example, stainless steel, resin, or the like. As shown in FIGS. 1 and 2, the second impeller 62 includes a discharge portion 62a provided on the outer peripheral side of the second impeller 62 and a suction portion 62b provided on one main surface side of the second impeller 62. The second impeller 62 is housed in the second pump casing 61 with the suction portion 62b facing upward in the axial direction. For example, the second impeller 62 has a pair of shrouds, and the outer peripheral edges of the pair of shrouds form the discharge portion 62a, and the suction portion 62b is formed at the center of one of the shrouds.

[0046] As shown in FIG. 2, the second partition plate 63 is 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, respectively. The second partition plate 63 partitions between the adjacent casings 34, 61 and the casing cover 35 and forms an accommodation space for accommodating the second impeller 62 between the opposing second pump casings 61. Further, as shown in FIG. 5, the second partition plate 63 is disposed opposite to the shroud in which the suction portion 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.

[0047] The second plate portion 63a has an opening formed at the center side for arranging the suction portion 62b of the second impeller 62. The surface of the second plate portion 63a facing the shroud of the second impeller 62 is formed in a shape along the outer surface of the shroud. Further, on the surface of the second plate portion 63a on the side opposite to the surface facing the second impeller 62 in the axial direction of the main shaft 12, a plurality of guide vanes 63b are integrally formed. For example, the surface of the second plate portion 63a where the plurality of guide vanes 63b are provided (i.e., the surface on the side opposite to the surface facing the second impeller 62) has the outer peripheral edge and the central side protruding axially on the side opposite to the second impeller 62, and a recess 63c is formed between the outer peripheral edge and the central side, which is recessed toward the second impeller 62 side, between adjacent guide vanes 63b.

[0048] Therefore, in the posture where the surface of the second plate portion 63a where the plurality of guide vanes 63b are provided is upward in the gravitational direction, the recess 63c has an inverse gradient for water to accumulate. In the present embodiment, since the suction portion 62b of the second impeller 62 faces upward in the posture where the main shaft 12 of the pump device 1 is in the gravitational direction, when draining the water in the pump 13, water accumulates in the recess 43c. That is, the recess 43c becomes a portion forming an inverse gradient arranged in the inner cylinder portion 71 of the second pump casing 61.

[0049] The plurality of guide vanes 63b guide the water from the primary side to the suction portion 62b of the second impeller 62 arranged at the opening of the second plate portion 63a. For example, the plurality of guide vanes 63b of the second partition plate 63 provided between adjacent second pump casings 61 face the plurality of return vanes 61d of the second pump casing 61, and together with the plurality of return vanes 61d, form a return flow path 61b.

[0050] The second pump group 33A forms a second casing flow path 33a in which a plurality of openings 54 communicate axially by laminating a plurality of second pump casings 61 and a central casing 34. Further, in the second pump group 33A, the central casing 34, a plurality of second pump casings 61, and a casing cover 35 are laminated, and a second partition plate 63 is 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. And in the second pump group 33A, a flow path for water pressurized by a plurality of second impellers 62, which is continuous with the second casing flow path 33a, is formed in a plurality of inner cylinder portions 71.

[0051] 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 settings for various design values such as blade diameter and suction diameter.

[0052] As shown in FIG. 6, the central casing 34 includes an inner cylinder portion (third inner cylinder portion) 81, an outer cylinder portion (third outer cylinder portion) 82 that covers the inner cylinder portion 81, and a plurality of ribs (third ribs) 83 that integrally connect the inner cylinder portion 81 and the outer cylinder portion 82. The central casing 34 is connected to the 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.

[0053] The central casing 34 houses the first impeller 42 and the second impeller 62 inside. Further, the central casing 34 constitutes an ascending flow path 34a that guides the water pumped upward from the housed first impeller 42 to the second casing flow path 33a, and a descending flow path 34b that guides the water pumped downward from the housed second impeller 62 to the first casing flow path 32a.

[0054] The inner cylinder part 81 has a plate part 81a that divides the center in the axial direction. The inner cylinder part 81 has a storage part 41a that stores the first impeller 42 provided on the lower side partitioned by the plate part 81a, and a storage part 61a that stores the second impeller 62 provided on the upper side. That is, the central casing 34 constitutes a part of the first pump part 32 and a part of the second pump part 33. Also, at the central part of the plate part 81a, a cylindrical lining part is provided that faces the sleeve provided on the pump main shaft 22 with a minute gap.

[0055] Also, as shown in FIG. 2, a water bearing 81b is provided in the lining part of the plate part 81a. The water 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.

[0056] The outer cylinder part 82 is continuously integrated with the inner cylinder part 81 by a plurality of ribs 83. The same number of the plurality of ribs 83 are formed at the same positions as the first pump casing 41 and the second pump casing 61. Such an outer cylinder part 82 is provided with a plurality of openings 91 that communicate with the upper side and the lower side of the inner cylinder part 81, which are partitioned by the plate part 81a of the inner cylinder part 81 and the plurality of ribs 83. The openings 91 are formed in the same number and the same shape as the openings 54, 74 of the first pump casing 41 and the second pump casing 61.

[0057] The outer cylinder part 82 has an engaging part (third engaging part) 82a or a engaged part (third engaged part) 82b that engages with the engaged part 52b or the engaging part 52a of the adjacent first pump casing 41, and an engaged part 82b or an engaging part 82a that engages with the engaging part 72a or the engaged part 72b of the adjacent second pump casing 61.

[0058] The engaging part 82a and the engaged part 82b are formed such that one can be inserted into the other. For example, the outer diameter of the engaging part 82a is the same diameter as the inner diameter of the engaged part 82b, or is formed to be slightly smaller in diameter than the engaged part 82b, and the engaging part 82a is inserted into the engaged part 82b.

[0059] The plurality of openings 91 each include a first opening 91a and a second opening 91b formed by partitioning in two in the circumferential direction.

[0060] In the first opening 91a, the lower side of the inner cylinder portion 81 partitioned by the plate portion 81a opens to the inner peripheral surface of the inner cylinder portion 81, and the upper side is closed with respect to the inner peripheral surface of the inner cylinder portion 81. The lower side of the first opening 91a that opens to the inner peripheral surface of the inner cylinder portion 81 is continuous with the storage portion 41a, and the upper side that is closed with respect to the inner peripheral surface of the inner cylinder portion 81 is continuous with the opening 74 of the second pump casing 61.

[0061] In the second opening 91b, the upper side of the inner cylinder portion 81 partitioned by the plate portion 81a opens to the inner peripheral surface of the inner cylinder portion 81, and the lower side is closed with respect to the inner peripheral surface of the inner cylinder portion 81. The upper side of the second opening 91b that opens to the inner peripheral surface of the inner cylinder portion 81 is continuous with the storage portion 61a, and the lower side that is closed with respect to the inner peripheral surface of the inner cylinder portion 81 is continuous with the opening 54 of the first pump casing 41.

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

[0063] Such a central casing 34 has an ascending flow path 34a in which the storage portion 41a of the inner cylinder portion 81 and the plurality of first openings 91a connect the secondary side of the first pump group 32A and the second casing flow path 33a of the second pump group 33A. Further, the central casing 34 has a descending flow path 34b in which the storage portion 61a of the inner cylinder portion 81 and the plurality of second openings 91b connect the secondary side of the second pump group 33A and the first casing flow path 32a of the first pump group 32A.

[0064] The casing cover 35 covers the uppermost second pump casing 61. The casing cover 35 forms a flow path that passes through the inside of the first impeller 42 from the suction port 31a of the flow path cover 31, and guides the water pumped up through 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 a first hole portion 35b into which the temporary assembly bolt 37 is inserted and a second hole portion 35c into which the main bolt 38 is inserted.

[0065] The first hole portion 35b is formed so as to be able to fix the temporary assembly bolt 37. For example, the inner peripheral surface of the first hole portion 35b is formed with an internal thread. The first hole portions 35b are provided in the same number as the temporary assembly bolts 37 and are arranged at symmetric positions.

[0066] The second hole portions 35c are provided in the same number as the main bolts 38. The plurality of second hole portions 35c are symmetrically arranged, for example, around the axis of the flange portion 35a.

[0067] The seal member 36 is, for example, an O-ring. By being compressed between the components, the seal member 36 prevents water inside the components from leaking. As a specific example, the seal member 36 is 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.

[0068] The temporary assembly bolt 37 has, for example, male thread portions 37a formed at both ends. One end is fixed by screwing into the first hole portion 35b of the casing cover 35, the other end is inserted into the hole portion 44 of the lowermost first pump casing 41, and is screwed with the nut 37b.

[0069] The temporary assembly bolt 37 is fastened to the first hole portion 35b and the nut 37b, and presses and fixes, for example, a plurality of first pump casings 41, which are central casings constituting at least the pump 13, the central casing 34, and a plurality of second pump casings 61 in a direction approaching each other. In the present embodiment, the temporary assembly bolt 37 fixes, for example, the plurality of first pump casings 41, the central casing 34, the plurality of second pump casings 61, and the casing cover 35. The temporary assembly bolt 37 has a length from the lowermost first pump casing 41 to the first hole portion 35b of the flange portion 35a of the casing cover 35. Note that the temporary assembly bolt 37 is used as a temporary fixture to temporarily fix each component when assembling the pump 13, but the pump device 1 may be configured without the temporary assembly bolt 37 as long as the pump 13 can be assembled and fixed.

[0070] There are a plurality of main bolts 38, and the number of main bolts 38 is set to be larger than that of the temporary assembly bolts 37. Also, the outer diameter of the main bolt 38 is set to be the same as that of the temporary assembly bolt 37 or larger than that of the temporary assembly bolt 37.

[0071] For example, male screw portions 38a are formed at both ends of the main bolt 38. One end is screwed into the fixing portion 31d of the base 31c of the flow path cover 31, and the other end is inserted into the second hole portion 35c of the casing cover 35 and screwed with the nut 38b.

[0072] For example, the main bolt 38 has a length from the base 31c of the flow path cover 31 to the second hole portion 35c of the flange portion 35a of the casing cover 35. By fastening the main bolt 38 to the second hole portion 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 and fixed in a direction approaching each other.

[0073] The drain hole 39 is formed in the casings 34, 41, 61 where a reverse gradient occurs inside the inner cylinder parts 51, 71, 81. Here, the reverse gradient is a recess that does not drain naturally in the direction of gravity in the posture of using the pump device 1. For example, it is a gradient in the direction opposite to the flow direction (flowing water direction) of the water flowing inside the casings 34, 41, 61 when the pump device 1 is driven. The drain hole 39 connects the internal space of the inner cylinder parts 51, 71, 81 where the reverse gradient occurs and the outside of the casings 34, 41, 61. In the example of the present embodiment, as shown by the two-dot chain line R in FIG. 1, a reverse gradient that is recessed in the direction of gravity is formed by the recess 63c of the second partition plate 63. Therefore, the drain hole 39 is provided in the second pump casing 41 in which a plurality of return vanes 61d that form the return flow path 61b are formed together with the plurality of guide vanes 63b of the second partition plate 63 where the reverse gradient occurs. Further, the drain hole 39 is provided at a position communicating with a space located above the reverse gradient when the pump device 1 is provided in a posture where the axial direction of the main shaft 12 is along the direction of gravity. Therefore, in the example of the present embodiment, the drain hole 39 is formed at a site where the return flow path 61b of the inner cylinder part 71, which is the space above the recess 63c of the second partition plate 63, is formed.

[0074] The drain hole 39 is a hole that penetrates the inner cylinder parts 51, 71, 81, the ribs 53, 73, 83, and the outer cylinder parts 52, 72, 82. For example, among the plurality of ribs 53, 73, 83 formed in the casings 34, 41, 61, the ribs 53, 73, 83 in which the drain hole 39 is formed are formed to have a width at least partially such that the drain hole 39 can have a predetermined inner diameter. Here, the predetermined inner diameter of the drain hole 39 is such that water does not stay in the drain hole 39 due to surface tension and water can pass through.

[0075] For example, as shown in FIG. 4, the ribs 53, 73, 83 in which the drain hole 39 is formed are formed in a streamline shape with respect to the flow direction of water in the flow paths (the first casing flow path 32a, the second casing flow path 33a, the ascending flow path 34a, the descending flow path 34b) formed between the inner cylinder parts 51, 71, 81 and the outer cylinder parts 52, 72, 82.

[0076] Further, the drain hole 39 is provided between the suction port 31a and the discharge port 31b around the rotation center of the main shaft 12. As a specific example, it is provided at a position that is out of phase by about 90° around the rotation center of the main shaft 12 with respect to the suction port 31a and the discharge port 31b that are arranged at 180° intervals. This is to prevent the suction port 31a and the discharge port 31b from interfering with the ground G2 when draining water from the drain hole 39 in a state where the pump device 1 is placed on the ground G2 with the main shaft 12 of the pump device 1 in a lateral orientation, that is, in a posture where the pump device 1 is laid down.

[0077] Such a drain hole 39 is used when draining the water in the pump 13 after the performance test before the shipment of the pump device 1, and then, at the time of shipment, it is hermetically sealed in an openable and closable manner by a sealing member 40 such as a plug. For this reason, the drain hole 39 is arranged so as to be displaced from the temporary assembly bolts 37 and the main bolts 38 around the rotation center of the main shaft 12 while ensuring the detachability of the sealing member 40. Note that the sealing member 40 is not limited to a plug, and may be a detachable one before shipment and a non-detachable one at the time of shipment.

[0078] The pump device 1 configured as described above has a drain hole 39 that connects the inner cylinder parts 51, 71, 81 to the outside of the casings 34, 41, 61 in at least the casings 34, 41, 61 having a portion or component with an inverse gradient inside, among the central casing 34, the first pump casing 41, and the second pump casing 61 having a double-casing structure as the pump 13. In this embodiment, the drain hole 39 is formed in the inner cylinder part 71 of the second pump casing 61 disposed above the second partition plate 63 that forms the return flow path 61b together with the second partition plate 63. As a result, after the water inside the pump 13 is drained in the gravitational direction after the drive of the pump device 1, by laying the pump device 1 down, the remaining water stored in the recess 63c of the second partition plate 63 having an inverse gradient can be drained from the drain hole 39. When the inverse gradient is formed by elements other than the recess 63c of the second partition plate 63, the same effect can be obtained by providing the drain hole 39 in the inner cylinder parts 51, 71, 81 of the casings 34, 41, 61 where this inverse gradient is formed. In this way, the pump device 1 can drain the water inside the pump 13 in both the vertical and horizontal postures, and can suppress the remaining water after draining even if there is an inverse gradient inside. Therefore, it is possible to suppress the leakage of the remaining water from the pump device 1 after shipment.

[0079] Further, by providing the drain hole 39 across the inner cylinder parts 51, 71, 81, the ribs 53, 73, 83, and the outer cylinder parts 52, 72, 82, it is possible to prevent the drain pipe forming the drain hole 39 from existing in the flow path between the inner cylinder parts 51, 71, 81 and the outer cylinder parts 52, 72, 82. Therefore, the pump device 1 can suppress an increase in the flow resistance of the flowing water between the inner cylinder parts 51, 71, 81 and the outer cylinder parts 52, 72, 82.

[0080] Also, by making the ribs 53, 73, 83 streamline-shaped, even when the shape of the ribs 53, 73, 83 where the drain hole 39 is arranged becomes large to ensure the strength when the drain hole 39 is formed, as shown in FIG. 4, the flow of water can be guided and an increase in the flow resistance can be suppressed. An example of the water flow direction in FIG. 4 is indicated by an arrow.

[0081] Moreover, by providing the drain holes 39, it is possible to facilitate the drainage of the water in the casings 34, 41, and 61 where an adverse gradient occurs. Therefore, even in the case of a self-balancing pump like the pump device 1 of the embodiment where an adverse gradient occurs and it is difficult to drain the water, the remaining water can be suppressed.

[0082] As described above, according to the pump device 1 according to an embodiment of the present invention, by forming the drain holes 39 in the inner cylinder parts 51, 71, and 81 where an adverse gradient occurs inside, it is possible to suppress the occurrence of remaining water after drainage.

[0083] Note that the present invention is not limited to the above-described embodiments. For example, in the above example, in order to make the self-balancing pump device 1, as a configuration having a plurality of impellers, the first impeller 42 and a plurality of second impellers 62 arranged in different directions have been described, but it is not limited to this. For example, the pump device 1 may have a configuration in which a plurality of impellers are arranged in the same direction.

[0084] Also, in the above example, the configuration in which the drain holes 39 are formed in at least any one of the ribs 53, 73, and 83 and the ribs 53, 73, and 83 in which the drain holes 39 are formed are streamlined in the water flow direction has been described. However, as long as the drain holes 39 can be formed, the ribs 53, 73, and 83 do not have to be streamlined, and a part of the ribs 53, 73, and 83 may protrude in a shape that enables the formation of the drain holes 39. Further, even if the drain holes 39 are formed, the thickness of the ribs 53, 73, and 83 may be increased so that the strength of the thickness between the inner surface of the drain holes 39 and the outer surface of the ribs 53, 73, and 83 can be sufficiently ensured. However, making the ribs 53, 73, and 83 in which the drain holes 39 are formed streamlined is advantageous from the viewpoint of fluid resistance. Also, the pump device 1 may have a configuration in which all the ribs 53, 73, and 83 are formed in a shape that can be formed, for example, streamlined, and the drain holes 39 are formed only in the ribs 53, 73, and 83 at desired positions.

[0085] Note that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist thereof at the implementation stage. Also, the respective embodiments may be implemented in appropriate combinations, and in such cases, the combined effects can be obtained. Furthermore, the above-described embodiments include various inventions, and various inventions can be extracted by combinations selected from a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiments, if the problems can be solved and the effects can be obtained, the configuration from which these constituent elements are deleted can be extracted as an invention.

Explanation of Signs

[0086] 1…Pump device, 11…Motor, 12…Spindle, 11a…Motor casing, 12…Spindle, 13…Pump, 21…Motor spindle, 22…Pump spindle, 22a…Mechanical seal, 23…Shaft joint, 31…Flow path cover, 31a…Suction port, 31b…Discharge port, 31c…Base, 31d…Fixing part, 32A…First pump group, 32…First pump part, 32a…First casing flow path, 33A…Second pump group, 33…Second pump part, 33a…Second casing flow path, 34…Central casing (casing), 34a…Ascending flow path, 34b…Descending flow path, 35…Casing cover, 35a…Flange part, 35b…First hole part, 35c…Second hole part, 36…Sealing member, 37…Temporary assembly bolt, 37a…Male thread part, 37b…Nut, 38…Main bolt, 38a…Male thread part, 38b…Nut, 39…Drain hole, 40…Sealing member, 41…First pump casing (casing), 41a…Storage part, 41b…Flow path, 41c…Guide vane, 41d…Vane, 41e…Liner lining, 41f…Submerged bearing, 42…First impeller (impeller), 42a…Discharge part, 42b…Suction part, 43…First partition plate, 44…Hole part, 51…Inner cylinder part (first inner cylinder part), 52…Outer cylinder part (first outer cylinder part), 52a…Engaging part (first engaging part), 52b…Engaged part (first engaged part), 53…Rib (first rib), 54…Opening, 61…Second pump casing (casing), 61a…Storage part, 61b…Flow path, 61c…Guide vane, 61d…Vane, 61e…Liner lining, 62…Second impeller (impeller), 62a…Discharge part, 62b…Suction part, 63…Second partition plate, 71…Inner cylinder part (second inner cylinder part), 72…Outer cylinder part (second outer cylinder part), 72a…Engaging part (second engaging part), 72b…Engaged part (second engaged part), 73…Rib (second rib), 74…Opening, 81…Inner cylinder part (third inner cylinder part), 81a…Plate part, 81b…Submerged bearing, 82…Outer cylinder part (third outer cylinder part), 82a…Engaging part (third engaging part), 82b…Engaged part (third engaged part), 83…Rib (third rib), 91…Opening part, 91a…First opening part, 91b…Second opening part, 92…Guide vane, G1…Installation surface, G2…Ground.

Claims

1. A plurality of impellers, an inner cylinder part that houses the impellers and forms a flow path, an outer cylinder part that houses the inner cylinder part and forms a flow path continuous with the flow path of the inner cylinder part between the outer cylinder part and the inner cylinder part, and a plurality of ribs formed between the inner cylinder part and the outer cylinder part, a plurality of casings stacked on each other, comprising: In the casing having a concave portion that is a reverse gradient in which water does not naturally drain in the gravitational direction and water accumulates, an openable and closable drain hole is formed that is continuous with the outside of the inner cylinder part and the outer cylinder part and drains the remaining water stored in the concave portion, a pump device.

2. The drain hole is formed across the inner cylinder part, the rib, and the outer cylinder part. The pump device according to claim 1.

3. The rib in which the drain hole is formed is formed in a streamline shape with respect to the flowing direction of the water flowing through the flow path. The pump device according to claim 2.

4. Comprising a flow path cover provided at the lowermost stage of the casing and having a suction port and a discharge port arranged symmetrically around the rotation center of the impeller, The drain hole is formed between the suction port and the discharge port around the rotation center. The pump device according to claim 2.

5. The plurality of impellers include a plurality of first impellers and a plurality of second impellers arranged in a direction different from that of the first impellers. The pump device according to any one of claims 1 to 4.

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