JP2017015035A - Fluid machinery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide fluid machinery which inhibits occurrence of cavitation of a closed type impeller with a simple structure and achieves excellent net positive suction head.SOLUTION: A vortex pump 10 is fluid machinery and includes: a rotary shaft 25 and an impeller 30 disposed in a casing 11. The impeller 30 includes: blades 31; a front shroud 37 disposed at one end side of the blades 31; and a rear shroud 40 disposed at the other end side of the blades 31. Each blade 31 has a protruding part 34 which protrudes inward from an opening part 38 side end part 38a of the front shroud 37.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a turbo fluid machine.

  A fluid machine (including a pump used for drainage, a generator used for power generation, and a pump turbine used for both drainage and power generation) includes a casing provided with a liquid flow path for flowing a liquid. In the casing, a rotating shaft is rotatably disposed and an impeller is disposed. The impeller is connected so as not to rotate relative to the rotation shaft.

  The impeller includes a plurality of blades extending radially outward from the base end portion on the rotating shaft side. In addition, the impeller includes a closed type in which shrouds are arranged at both front and rear ends of the vane plate in a direction in which the rotation axis extends, and an open type in which shrouds are arranged only at the rear end of the vane plate. The closed type impeller is an open type because it is easy to set the gap between the casing wall and the blade plate, there is no need for adjustment after being assembled to the casing, and there is little reduction in efficiency due to wear. Better than the impeller. Therefore, many closed-type impellers are used for pumps.

  However, since a closed-type impeller has a pressure difference between the first entrance / exit side, which is the base end side of the vane plate, and the second entrance / exit side, which is the tip end side of the vane plate, Cavitation is likely to occur on the edge side. When cavitation occurs, in the case of a pump, there is a disadvantage that the lift is lowered and the suction capacity (NPSH) is lowered. On the other hand, the open type impeller has an excellent NPSH (Net Positive Suction Head) compared to the closed type impeller by appropriately setting the gap between the impeller and the liquid flow path wall. . However, when the gap between the blade plate and the wall is increased by use, there is a problem that NPSH is inferior to the closed type impeller.

  Patent Document 1 discloses an impeller (runner of a water turbine) that can reduce the occurrence of cavitation by providing a through hole in a blade plate of a closed type impeller. However, it is very difficult to provide a through-hole in a blade plate whose front and rear ends are closed by a shroud.

JP-A-5-99115

  It is an object of the present invention to provide a fluid machine with a simple structure that suppresses the occurrence of cavitation in a closed impeller and is excellent in NPSH.

  The present invention includes a rotating shaft rotatably disposed in a casing, and an impeller disposed in the casing and connected to the rotating shaft, and the impeller includes a base end portion on the rotating shaft side. A plurality of blades having a distal end opposite to the base end extending radially outward from the base end, and an opening is formed on the base end side of the blade, A first shroud disposed on one end side of the vane plate in the direction in which the rotation shaft extends, and a second shroud disposed on the other end side of the vane plate in the direction in which the rotation shaft extends with a distance from the first shroud. A fluid machine including a shroud, wherein the blade has a protruding portion protruding from an end portion of the first shroud on the opening side.

  The impeller of this fluid machine is a closed type in which a first shroud and a second shroud are disposed at both ends of a blade plate. Therefore, it is easy (unnecessary) to set a gap between the wall of the casing and the blade, and adjustment after being assembled to the casing is unnecessary, so that assemblability and maintainability can be improved. In addition, the efficiency can be maintained because there is little decrease in efficiency due to wear. Further, since the pressures before and after the impeller, which is the direction in which the rotation shaft extends, are balanced by the first shroud and the second shroud, it is possible to prevent a large axial thrust from acting like an open impeller.

  Moreover, the impeller of this aspect is partially open type by providing a protruding portion that protrudes inwardly from the opening of the first shroud on the base end side of the blade plate. Therefore, when the base end side of the slats becomes negative pressure, the liquid in the arrangement space between the first shroud and the casing wall flows to the projecting part of the slats. Thereby, the pressure difference of the base end part side and front-end | tip part side of a slat can be reduced. Therefore, the generation of cavitation can be suppressed and the suction performance (necessary NPSH) can be improved without greatly changing the performance of the closed type impeller. Moreover, the protrusion part of a slat can be easily provided by processing the opening part of the surface 1st shroud.

  The protruding portion of the blade includes the entire base end portion from one end of the base end portion located on the first shroud side to the other end of the base end portion located on the second shroud side. According to this aspect, since the pressure difference between the base end portion side and the tip end portion side of the blade can be greatly reduced, the occurrence of cavitation can be reliably suppressed and the necessary NPSH can be improved.

  The casing includes a protector positioned on the first shroud side of the impeller at a distance from the protrusion of the impeller. According to this aspect, the liquid in the arrangement space can be reliably guided to the protruding portion of the blade. Moreover, since the protrusion part and protector exposed from the opening part can be processed easily, the flow rate of the liquid flowing from the arrangement space part to the protrusion part can be easily adjusted.

  A water passage formed between the protector and the edge of the opening includes a first portion extending in a radial direction of the impeller, and a first portion extending in an axial direction of the impeller continuously to the first portion. A stepped structure having two parts and a third part extending in the radial direction of the impeller continuously to the second part. According to this aspect, not only the flow rate of the liquid flowing from the arrangement space portion to the protruding portion, but also the flow direction of the liquid can be adjusted by the water flow portion having the first portion to the third portion.

  A labyrinth is provided between the protector and the first shroud. According to this aspect, the labyrinth forms a wide portion and a narrow portion in the cross-sectional area of the water flow portion. Therefore, the liquid flowing to the protruding portion is decelerated by the portion having the wide gap cross-sectional area, and the cavitation can be effectively eliminated by increasing the pressure.

  Since the impeller of the fluid machine of the present invention is a partially open type provided with a protruding portion that protrudes inwardly from the opening of the first shroud on the impeller, without greatly changing the performance of the closed impeller, The occurrence of cavitation can be suppressed and the required NPSH can be improved.

Sectional drawing of the single suction centrifugal vortex pump which is the fluid machine of 1st Embodiment. The front view which looked at the impeller from the front shroud side. The figure which shows the relationship between the liquid flow path of an impeller, and the pressure of a liquid. Sectional drawing which shows the casing and impeller of 2nd Embodiment. Sectional drawing which shows the casing and impeller of 3rd Embodiment. Sectional drawing which shows the casing and impeller of 4th Embodiment. Sectional drawing which shows the casing and impeller of 5th Embodiment. Sectional drawing of the double suction centrifugal vortex pump which is the fluid machine of 6th Embodiment. Sectional drawing of the double suction centrifugal centrifugal pump of 7th Embodiment. Sectional drawing which shows the case where an impeller is used for a generator.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows a turbo-type single-suction centrifugal centrifugal pump 10 that is a fluid machine according to a first embodiment of the present invention. The centrifugal pump 10 includes a casing 11 in which a volute passage 16 is formed. In the casing 11, a rotating shaft 25 is rotatably disposed and an impeller 30 connected to the rotating shaft 25 is disposed. In the present embodiment, a substantially closed impeller 30 is used, the occurrence of cavitation by the closed impeller 30 is suppressed, and the required NPSH is improved.

(Details of single suction centrifugal centrifugal pump)
The casing 11 of the centrifugal pump 10 includes a casing body 12 and a casing cover 13 fixed to the casing body 12. The casing body 12 is provided with a suction port 14 on the left side in FIG. The suction port 14 is a space having a circular cross section, and the axis extends along the direction Y in which the rotation shaft 25 extends. An arrangement space portion 15 in which the impeller 30 is arranged is provided at an end portion of the suction port 14. A volute passage 16 that is a liquid flow path for discharging the liquid sucked into the casing 11 to the downstream side is provided on the outer peripheral portion of the arrangement space portion 15. The volute passage 16 extends in a spiral shape along a plane extending in the orthogonal (radial) direction X with respect to the axis of the rotary shaft 25. The volute passage 16 communicates with the suction port 14 through the arrangement space portion 15. The casing body 12 is provided with a discharge port 17 that is an outlet of the volute passage 16 so as to be positioned on the upper side in FIG. Note that pipes (not shown) are connected to the suction port 14 and the discharge port 17, respectively.

  A rotating shaft 25 is rotatably disposed in the casing 11 so as to extend in the horizontal direction. One end of the rotating shaft 25 protrudes from the shaft hole 18 of the casing cover 13 into the arrangement space portion 15. A seal 19 is attached around the shaft hole 18 to maintain liquid tightness. A bearing case 20 is fixed to the outside of the casing cover 13. The rotating shaft 25 is rotatably supported by a bearing 21 fixed to the bearing case 20. A motor which is a driving means (not shown) is connected to the outer end of the rotating shaft 25 protruding from the bearing case 20.

  As shown in FIGS. 1 and 2, a circular impeller 30 is arranged in the casing 11 so as to be positioned in the arrangement space portion 15 when viewed from the direction Y in which the rotation shaft 25 extends. The impeller 30 is fixed so as not to rotate relative to the rotation shaft 25, and is rotated forward by the rotation of the rotation shaft 25, whereby the liquid is sucked from the suction port 14 and discharged from the discharge port 17.

(Details of impeller)
The impeller 30 includes a plurality of blade plates 31, a front shroud (first shroud) 37 disposed on the front side of the blade plate 31, and a rear shroud (second shroud) 40 disposed on the rear side of the blade plate 31. Is provided.

  The blade 31 includes a proximal end portion 32 on the rotating shaft 25 side and a distal end portion 33 on the opposite side to the proximal end portion 32. The blade 31 extends radially outward from the base end portion 32 in the radial direction X and is curved in the circumferential direction. The shape, posture, dimensions, number, arrangement, and the like of the blades 31 are set so that air bubbles are not generated when bubbles are sucked.

  The front shroud 37 is disposed at the front end (one end side) 31a of the blade 31 in the direction Y in which the rotation shaft 25 extends. The front shroud 37 is provided with an opening 38 so as to be concentric with the rotary shaft 25. The center of the front shroud 37 including the opening 38 is raised in a conical cylinder shape toward the suction port 14. The outer periphery of the front shroud 37 has a flat plate shape extending in a direction orthogonal to the direction Y in which the rotation shaft 25 extends.

  The rear shroud 40 is generally disc-shaped, and is disposed at the rear end (other end side) 31b of the blade 31 in the direction Y in which the rotation shaft 25 extends. Thereafter, the shroud 40 is located at a predetermined interval with respect to the front shroud 37. As shown in FIG. 1, a connecting portion 41 for connecting the rotating shaft 25 is provided at the center of the rear shroud 40. Further, the rear shroud 40 is provided with a cylindrical portion 42 that protrudes toward the casing cover 13 so as to be concentric with the connecting portion 41.

  The impeller 30 is formed with a plurality of cylindrical liquid flow paths 44 defined by adjacent blade plates 31, 31, a front shroud 37, and a rear shroud 40. In the impeller 30, an opening 38 on the base end portion 32 side of the vane plate 31 is an inflow port, and liquid is sucked from the opening 38. The tip 33 of the vane plate 31 of the liquid flow path 44 communicating with the opening 38 is an outlet, and the liquid is discharged radially outward through the liquid flow paths 44 by the centrifugal force generated by the rotation of the rotary shaft 25. The

  As shown in FIGS. 2 and 3, the vane plate 31 of the impeller 30 includes a protrusion 34 that protrudes inwardly from an end 38 a on the opening 38 side of the front shroud 37 when viewed from the front shroud 37 side. . The protrusion 34 is exposed from the opening 38 by, for example, notching and expanding the opening 38 of the existing front shroud 37. Thus, the protrusion 34 can be easily provided by processing the opening 38 of the front shroud 37 on the surface. Moreover, since the protrusion part 34 is exposed from the opening part 38, cleaning property is favorable.

  The base end portion 32 of the blade plate 31 is directed in the radial direction of the impeller 30 from the first end (one end) 32 a located on the front shroud 37 side toward the second end (other end) 32 b located on the rear shroud 40 side. X is inclined inward. The end portion 38a of the opening 38 is closer to the distal end portion 33 side of the blade plate 31 than the first end 32a of the base end portion 32 of the blade plate 31 located on the front side in the direction in which the rotating shaft 25 extends (outside in the radial direction X It is set so as to be located in the rear direction Y). Preferably, the inner edge of the opening 38 is set so as to be positioned closer to the distal end portion 33 of the blade 31 than an intermediate position between the first end 32a and the second end 32b of the base end 32 of the blade 31. Is done. More preferably, the inner edge of the opening portion 38 is set to be positioned closer to the distal end portion 33 side of the blade plate 31 than the second end 32b of the base end portion 32 of the blade plate 31 positioned away from the suction port 14. . And the diameter of the opening part 38 of this embodiment is set so that the whole base end part 32 which is the 1st end 32a of the base end part 32 from the 2nd end 32b may be included. That is, the protrusion 34 includes the entire base end portion 32.

  The impeller 30 thus configured is a closed type in which front and rear shrouds 37 and 40 are disposed at both ends of the blade plate 31. For this reason, it is easy (unnecessary) to set a gap between the wall 15a of the arrangement space portion 15 and the blade plate 31, and adjustment after assembling to the casing 11 is unnecessary, so that assemblability and maintainability can be improved. In addition, the efficiency can be maintained because there is little decrease in efficiency due to wear. Further, the front and rear shrouds 37 and the rear shroud 40 balance the pressures before and after the impeller 30 along the direction Y in which the rotating shaft 25 extends, so that it is possible to prevent a large axial thrust from acting like an open impeller. .

  As shown in FIGS. 1 and 3, a wear ring 46 is disposed between the rear shroud 40 and the casing cover 13 to partition the casing cover 13 and the discharge port 17 side. The wear ring 46 is made of a material having good sliding properties such as stainless steel, cast iron, bronze, and the like. Further, between the casing main body 12 and the front shroud 37, a protector 47 that partitions the suction space 14 side of the arrangement space portion 15 and the impeller 30 is arranged. This protector 47 is made of a material having good slidability like the wear ring 46.

  The protector 47 is arranged in a notch 49 provided in the inlet 48 of the arrangement space 15. By arranging the impeller 30 in the arrangement space portion 15, a gap having a set interval is formed between the wall 15 a of the arrangement space portion 15 and the front shroud 37. The protector 47 includes an end surface portion 50 that is located at a predetermined interval from the end portion 38 a of the opening 38 of the impeller 30. Between the end portion 38 a and the end surface portion 50 of the opening 38, a first water flow portion 54 that can inject the liquid in the arrangement space portion 15 toward the protruding portion 34 side of the blade 31 is formed. In addition, the protector 47 includes a facing surface portion 51 that is positioned at a set interval along the edge (front end 31 a) of the protruding portion 34 of the blade plate 31. Between the edge of this protrusion part 34 and the opposing surface part 51, the 2nd water flow part 55 which can pour the liquid of the arrangement | positioning space part 15 to the opening part 38 side via the 1st water flow part 54 is formed. . The cross-sectional area of the first water flow portion 54 and the cross-sectional area of the second water flow portion 55 are smaller than the cross-sectional area of the gap portion between the wall 15a of the arrangement space portion 15 and the front shroud 37. As a result, the liquid in the arrangement space 15 is poured into the protrusion 34 and the opening 38 with a predetermined pressure.

  Next, the pressure distribution from the inlet (opening 38) to the outlet when the liquid is drained by the impeller 30 will be described.

  As shown in FIG. 3, in the impeller 30, the pressure gradually decreases while the liquid reaches the base end portion 32 of the blade plate 31 from the opening 38. As shown by a broken line in FIG. 3, in the closed type impeller of the comparative example (conventional example) in which the blade plate 31 is not exposed from the opening 38, when the liquid reaches the first end 32 a of the base end portion 32, the pressure The descending slope of becomes steep. This steep pressure drop stops when it reaches the second end 32b of the base end portion 32, and reaches a minimum pressure at the second end 32b. When the liquid passes through the second end 32b of the base end portion 32 and reaches the liquid flow path 44, the pressure gradually increases. And it becomes maximum pressure in the exit part of the impeller 30. By increasing the difference between the minimum pressure and the maximum pressure, cavitation occurs on the base end portion 32 side of the blade 31 on the negative pressure side.

  The impeller 30 of this embodiment includes a protruding portion 34 that protrudes inward from the opening 38 of the front shroud 37 on the base end portion 32 side of the blade plate 31. In addition, a protector 47 facing the protruding portion 34 is disposed at the inlet portion 48 of the arrangement space portion 15. Therefore, the liquid existing between the impeller 30 and the wall 15a of the arrangement space portion 15 passes through the water passing portions 54 and 55 as shown by arrows in FIG. Water is poured into 32. This water injection increases the pressure on the inlet (base end portion 32) side of the blade 31 as shown by the solid line in FIG. Therefore, the pressure drop that occurs between the first end 32a and the second end 32b of the base end portion 32 of the blade 31 can be significantly suppressed.

  Thus, since the impeller 30 of this embodiment is a partially open type in which the base end portion 32 side of the blade plate 31 is protruded from the opening 38, the base end portion 32 side of the blade plate 31 has a negative pressure. As a result, the liquid in the arrangement space 15 is poured into the protrusion 34. In addition, the protruding portion 34 includes the entire base end portion 32 from the first end 32 a to the second end 32 b of the blade 31. Therefore, since the pressure difference between the base end portion 32 side and the tip end portion 33 side of the vane plate 31 can be greatly reduced, the occurrence of cavitation is suppressed without significantly changing the performance of the closed impeller 30, and the suction performance ( Necessary NPSH) can be improved.

  Further, the protector 47 arranged in the casing 11 can reliably inject the liquid in the arrangement space 15 into the protrusion 34. Further, by adjusting the cross-sectional area of the water flow portions 54 and 55 formed between the protector 47 and the impeller 30, the flow rate of the liquid flowing from the arrangement space portion 15 to the protruding portion 34 can be easily adjusted. In addition, since the adjustment of the liquid amount is performed by processing the protruding portion of the impeller 30, workability can be improved.

(Second Embodiment)
FIG. 4 shows the centrifugal pump 10 of the second embodiment. In this 2nd Embodiment, the 1st water flow part 54 formed between the protector 47 and the edge part 38a of the opening part 38 of the front shroud 37 is made into a stepped structure, From the arrangement | positioning space part 15, it is an impeller. This is different from the first embodiment in that the direction in which the liquid is poured into 30 is adjusted. Specifically, the first water flow portion 54 is continuous with the first portion 54a communicating with the arrangement space portion 15, the second portion 54b continuous with the end portion of the first portion 54a, and the end portion of the second portion 54b. A third portion 54c.

  The first portion 54 a is provided so as to extend along the radial direction of the impeller 30. The end portion of the first portion 54 a is located at a half thickness from the front surface side of the front shroud 37. The second portion 54 b is provided to extend in the axial direction of the impeller 30 by providing a step at the end 38 a of the opening 38 of the front shroud 37 and by providing a step at the protector 47. The end portion of the second portion 54 b is located on the rear side in the axial direction Y from the second end 32 b of the base end portion 32 of the blade plate 31. The third portion 54 c is provided so as to extend along the radial direction X of the impeller 30. The end of the third portion 54 c is located at the inlet of the liquid flow path 44 of the impeller 30. The portion of the blade 31 that is located on the front side in the axial direction Y from the third portion 54c is the protruding portion 34 similar to the first embodiment.

  The first water flow portion 54 is set such that at least the gap cross-sectional areas A1 and A3 of the first portion 54a and the third portion 54c are different from each other among the first portion 54a to the third portion 54c. The gap cross-sectional area is a cross-sectional area in a direction orthogonal to the liquid flow direction. Specifically, the gap cross-sectional area A1 of the first portion 54a is set smaller than the gap cross-sectional area A0 of the arrangement space portion 15. The gap cross-sectional area A2 of the second portion 54b is set to be substantially the same or smaller than the gap cross-sectional area A1 of the first portion 54a. The gap cross-sectional area A3 of the third portion 54c is set smaller than the gap cross-sectional area A0 of the arrangement space portion 15 and larger than the gap cross-sectional area A1 of the first portion 54a.

Thus, in the 1st water flow part 54 which set clearance gap cross-sectional area A1-A3, the fluid velocity V3 of the 3rd part 54c which is an exit is computable with the following formula | equation (1).

Further, a portion where cavitation occurs in the impeller 30 is a region Pc indicated by an ellipse in FIG. The pressure P3 applied to the cavitation region by the liquid flowing out from the third portion 54c of the first water flow portion 54 can be calculated by the following equation (2).

Then, the relationship among the arrangement space pressure P0, the first partial pressure P1, the third partial pressure P3, the rotation shaft ambient pressure P4, and the cavitation region pressure Pc is expressed by the following equation (3). The discharge pressure P in the volute passage 16 that is the outlet of the impeller 30 is higher than the arrangement space pressure P0.

  Therefore, in this 2nd Embodiment, the effect | action and effect similar to 1st Embodiment can be acquired, and generation | occurrence | production of cavitation can be suppressed significantly by the 1st water flow part 54 made into the step structure. That is, the flow direction of the liquid flowing out from the first water flow portion 54 can be adjusted so as to flow in the cavitation region that is the negative pressure surface of the blade plate 31. Thereby, since the pressure Pc in the cavitation region is increased by the pressure P3 of the liquid injected from the third portion 54c, the pressure difference between the proximal end portion 32 side and the distal end portion 33 side can be reduced. Therefore, since the occurrence of cavitation on the base end portion 32 side of the blade 31 can be significantly suppressed, erosion due to cavitation can be reduced.

(Third embodiment)
FIG. 5 shows the centrifugal pump 10 of the third embodiment. This third embodiment is different from the second embodiment in that a labyrinth 57 is provided on the wall that defines the first water flow portion 54 between the protector 47 and the front shroud 37. In detail, the 1st water flow part 54 of 3rd Embodiment is a stepped structure provided with the 3rd part 54c from the 1st part 54a similarly to 2nd Embodiment. Among these, the labyrinth 57 is provided on the end surface portion 50 of the protector 47 constituting the third portion 54c. The labyrinth 57 is formed by providing a plurality of cutout grooves extending in the circumferential direction in the intersecting direction with the water flow direction as the axis.

  In the third embodiment configured as described above, the same operations and effects as those of the second embodiment can be obtained, and cavitation can be effectively eliminated by the labyrinth 57. That is, due to the notch groove of the labyrinth 57, the third portion 54c of the first water flow portion 54 is formed with a portion having a wide gap cross-sectional area and a portion having a narrow gap. The flow of the liquid passing through the third portion 54c is decelerated by the notch groove portion of the labyrinth 57 having a wide gap cross-sectional area. Thereby, the pressure in the cavitation region can be increased and cavitation can be effectively eliminated. Moreover, leakage loss can be reduced by decelerating the flow to the protrusion 34.

(Fourth embodiment)
FIG. 6 shows the centrifugal pump 10 of the fourth embodiment. The fourth embodiment is different from the third embodiment in that a labyrinth 57 is provided on the wall of the protector 47 constituting the second portion 54b of the first water flow portion 54. In the fourth embodiment thus configured, substantially the same operations and effects as those of the third embodiment can be obtained.

(Fifth embodiment)
FIG. 7 shows a centrifugal pump 10 of the fifth embodiment. The fifth embodiment is different from the respective embodiments in that the entire first water flow portion 54 has a labyrinth structure. Specifically, the first water flow portion 54 has a stepped structure including the first portion 54a to the fifth portion 54e. Among them, the second portion 54b extending to the front side in the axial direction Y of the impeller 30 is formed by a notch groove 58a extending beyond the third portion 54c. Similarly, the 4th part 54d is comprised by the notch groove 58b extended to the front side of the axial direction Y of the impeller 30 exceeding the 5th part 54e. The first notch groove 58a extends in the direction intersecting the water passage direction in the third portion 54c, and the second notch groove 58b extends in the direction intersecting the water passage direction in the fifth portion 54e.

  In the fifth embodiment, the direction in which the liquid flows can be adjusted by the first water flow portion 54 having a stepped structure. Moreover, the flow to the protrusion part 34 is decelerated by the notch grooves 58a and 58b, so that the pressure in the cavitation region can be increased and the cavitation can be effectively eliminated. Therefore, the same operation and effect as the third embodiment can be obtained.

(Sixth embodiment)
FIG. 8 shows a double suction centrifugal vortex pump 60 that is a fluid machine of a sixth embodiment. In the centrifugal pump 60, a suction chamber 70 is formed inside the casing 61, and a discharge chamber 71 is formed at the center in the width direction of the suction chamber 70. In addition, a rotating shaft 72 is passed through the casing 61 in the width direction, and an impeller 80 is connected to the rotating shaft 72. The impeller 80 can suck liquid from both ends in the direction in which the rotating shaft 72 extends, and the base end portions 86A and 86B of the vane plate 85 are the openings 91 of the left and right shrouds 90 and 93, as in each embodiment. It protrudes from 94.

(Details of double suction centrifugal centrifugal pump)
The casing 61 of the centrifugal pump 60 includes a casing body 62 and a casing cover 66. The casing main body 62 includes a suction pipe projecting from one end side of the front and rear and a discharge pipe projecting from the other end side of the front and rear. A suction port 63 is formed at the tip of the suction pipe, and a discharge port 64 is formed at the tip of the discharge pipe.

  At the center in the width direction of the casing body 62, a pair of left and right lower partition walls 65, 65 are provided at a predetermined interval. Similarly, a pair of left and right upper partition walls 67 and 67 are provided at the center in the width direction of the casing cover 66 so as to be positioned above the lower partition walls 65 and 65. By assembling the casing cover 66 to the casing body 62, the lower partition walls 65, 65 and the upper partition walls 67, 67 are formed in an annular shape with a circular mounting hole 68 formed in the center. The regions on both the left and right sides of the partition walls 65 and 67 are spiral suction chambers 70 communicating with the suction ports 63. A region inside the partition walls 65 and 67 is a spiral discharge chamber 71 that communicates with the suction chamber 70 through the attachment hole 68 and communicates with the discharge port 64.

  In the casing 61, an impeller 80 is disposed in the mounting hole 68 so as to be located in the discharge chamber 71, and a rotating shaft 72 is disposed so as to penetrate the impeller 80. At both left and right ends of the casing 61, mechanical seals 73 that rotatably support the rotary shaft 72 are arranged. As the rotating shaft 72 rotates, the impeller 80 rotates forward, sucks liquid from the suction port 63, and flows into the suction chamber 70. The impeller 80 sucks the liquid in the suction chamber 70 from both sides, sends the liquid to the discharge chamber 71 that is a liquid flow path, and discharges it from the discharge port 64.

(Details of impeller)
The impeller 80 of the sixth embodiment includes a connecting portion 82 for connecting to the rotating shaft 72, a plurality of blade plates 85 projecting radially from the connecting portion 82, and a left shroud disposed on one end side of the blade plate 85. (First shroud) 90 and right shroud (second shroud) 93 disposed on the other end side of vane plate 85 are provided.

  The connecting portion 82 includes a raised portion 83 that protrudes substantially in an isosceles triangle shape in order to guide the liquid sucked from both sides to the outlet. The vane plate 85 is integrally formed with the connecting portion 82 and protrudes from the outer peripheral portion of the raised portion 83. The slat 85 includes a pair of base end portions 86 </ b> A and 86 </ b> B on the right and left sides by a central raised portion 83. The distal end portion 87 of the vane plate 85 protrudes radially outward from the base end portions 86A and 86B.

  The left shroud 90 is disposed at the left end of the blade 85 in the direction in which the rotation shaft 72 extends. The left shroud 90 is provided with a first opening 91 so as to be concentric with the rotating shaft 72. The right shroud 93 is disposed at the right end of the blade 85 in the direction in which the rotation shaft 72 extends. The right shroud 93 is provided with a second opening 94 so as to be concentric with the rotating shaft 72.

  A plurality of cylindrical liquid flow paths 96 defined by adjacent blades 85, 85, a left shroud 90, and a right shroud 93 are formed in the both suction type impellers 80. In the impeller 80, the openings 91 and 94 on the base end portions 86 </ b> A and 86 </ b> B side of the blade plate 85 are inflow ports, and liquid is sucked from the openings 91 and 94. Further, the tip end 87 side of the vane plate 85 of the liquid channel 96 is an outflow port, and the liquid is discharged radially outward through each liquid channel 96 by the centrifugal force generated by the rotation of the rotating shaft 72.

  When viewed from the left shroud 90 side, the vane plate 85 of the impeller 80 includes a protruding portion 88 that protrudes inward from an end portion of the left shroud 90 on the first opening 91 side. The protrusion 88 protrudes inward from the end portion of the right shroud 93 on the second opening 94 side as viewed from the right shroud 93 side. The protruding portion 88 is exposed from the ends of the openings 91 and 94 by, for example, notching and expanding the openings 91 and 94 of the existing shrouds 90 and 93.

  The first opening 91 includes the entire base end portion 86A from one end of the base end portion 86A located on the left shroud 90 side to the second end of the base end portion 86A located on the connecting portion 82 (right shroud 93 side). Diameter. Similarly, the second opening 94 has a base end portion 86B from one end of the base end portion 86B located on the right shroud 93 side to the second end of the base end portion 86B located on the connecting portion 82 (left shroud 90 side). The diameter includes the whole. That is, the protrusion 88 includes the entire first base end portion 86A and the entire second base end portion 86B.

  In the mounting hole 68 formed by the lower partition wall 65 and the upper partition wall 67, protectors 98A and 98B that partition the suction chamber 70 and the suction chamber 70 are arranged. The protectors 98A and 98B are made of the same material as in the first embodiment. A first water passage 101 is formed between the protectors 98A and 98B and the left and right shrouds 90 and 93. The illustrated 1st water flow part 101 is provided with the 3rd part from the 1st part like the 2nd embodiment. Further, a second water passage portion 102 is formed between the protectors 98 </ b> A and 98 </ b> B and the edge of the protruding portion 88. The second water passage portion 102 injects the liquid between the wall of the arrangement space portion 100 that is the center side of the discharge chamber 71 and the shrouds 90 and 93 to the openings 91 and 94 via the first water passage portion 101. Is possible.

  The impeller 80 and the centrifugal pump 60 of the sixth embodiment thus configured can obtain the same operations and effects as those of the first embodiment. That is, since the impeller 80 is a partially open type in which the base end portions 86A and 86B of the blade plate 85 are exposed from the openings 91 and 94 provided in the pair of shrouds 90 and 93, the base end portions 86A and 86B. When the side becomes negative pressure, the liquid in the arrangement space 100 is poured into the protrusion 88. Therefore, the pressure difference between the base end portions 86A and 86B and the tip end portion 87 side of the vane plate 85 can be greatly reduced, so that the occurrence of cavitation is suppressed without significantly changing the performance of the closed impeller 80, and suction is performed. Performance (necessary NPSH) can be improved.

(Seventh embodiment)
FIG. 9 shows a centrifugal pump 60 of the seventh embodiment. The seventh embodiment is different from the sixth embodiment in that a partition plate portion 104 that partitions the liquid flow channel 96 left and right is provided at the center in the width direction of the impeller 80. Specifically, the partition plate portion 104 is provided so as to protrude from the top portion of the raised portion 83 of the connecting portion 82 to the tip portion 87 of the blade plate 85. In the seventh embodiment thus configured, the same operations and effects as in the sixth embodiment can be obtained.

  In addition, the fluid machine of this invention is not limited to the structure of the said embodiment, A various change is possible.

  For example, in each embodiment, the protrusions 34 and 88 of the blades 31 and 85 are formed so that the entire base end portions 32, 86A, and 86B are exposed from the openings 38, 91, and 94. 32, 86A, 86B may be exposed at least one end, and preferably more than half of the base end portions 32, 86A, 86B may be exposed. In each embodiment, separate protectors 47, 98A, and 98B are disposed in the casings 11 and 61. However, the protectors 47, 98A, and 98B may be integrally formed with the casings 11 and 61. Moreover, the structure of the 1st water flow parts 54 and 101 and the 2nd water flow parts 55 and 102 which pour the liquid of the arrangement | positioning space parts 15 and 100 to the protrusion parts 34 and 88 can also be changed as desired.

  In each of the above embodiments, the fluid machine of the present invention has been described by taking the centrifugal pumps 10 and 60 used for drainage as an example. However, the fluid machine includes a generator used for power generation, and both drainage and power generation. It may be a pump turbine used in the above. In addition, when using any impeller 30 and 80 of each embodiment as a runner of a water wheel, the front-end | tip parts 33 and 37 side of the impeller 30 and 80 becomes an inflow port, and the base end part 32 of the impeller 30 and 80, 86A, 86B side becomes an outflow port. That is, the liquid inlet / outlet is reversed between the pump and the water wheel.

  Moreover, when the impeller 30 of 1st Embodiment to 5th Embodiment is used for a water wheel, as shown with the broken line in FIG. 10, the diameter and inclination | tilt angle of the base end part 32 which are the protrusion parts 34 of the blade board 31 are set. By adjusting, the head, the flow rate and the output can be adjusted. The processing for adjusting the blade 31 can be easily performed because the base end portion 32 is exposed from the opening 38. Further, since there is a limit to the processing of the blade 31, the inner diameter is adjusted by cutting the protector 47 up to the processing line 105 shown by a one-dot chain line in FIG. 10. Thereby, the effect | action and effect similar to the process of the blade 31 can be acquired by adjusting the space | interval (gap sectional area of the 2nd water flow part 55) of the protector 47 and the edge of the protrusion part 34. FIG. The processing of the protector 47 can be easily performed in a state where the impeller 30 is not assembled. Of course, the same operation and effect can be obtained by using the impeller 80 of the sixth embodiment and the seventh embodiment as well for the water wheel.

DESCRIPTION OF SYMBOLS 10 ... Centrifugal pump 11 ... Casing 12 ... Casing main body 13 ... Casing cover 14 ... Suction port 15 ... Arrangement space part 16 ... Volute passage 15a ... Wall 17 ... Discharge port 18 ... Shaft hole 19 ... Seal 20 ... Bearing case 21 ... Bearing 25 ... Rotary shaft 30 ... Impeller 31 ... Blade 31a ... Front end (one end)
31b ... rear end (other end)
32 ... Base end portion 32a ... First end 32b ... Second end 33 ... Tip end portion 34 ... Projection portion 37 ... Front shroud 38 ... Opening portion 38a ... End portion 40 ... Rear shroud 41 ... Connecting portion 42 ... Cylindrical portion 44 ... Liquid Flow path 46 ... Wear ring 47 ... Protector 48 ... Inlet part 49 ... Notch part 50 ... End face part 51 ... Opposite face part 54 ... First water flow part 54a ... First part 54b ... Second part 54c ... Third part 54d ... Third part 4 part 54e ... 5th part 55 ... 2nd water flow part 57 ... Labyrinth 58a, 58b ... Notch groove 60 ... Centrifugal pump 61 ... Casing 62 ... Casing main body 63 ... Suction port 64 ... Discharge port 65 ... Lower partition wall 66 ... Casing cover 67 ... Upper partition wall 68 ... Mounting hole 70 ... Suction chamber 71 ... Discharge chamber 72 ... Rotating shaft 73 ... Mechanical seal 80 ... Impeller 82 ... Connection part 83 ... Raised part 85 ... Blades 86A, 86B ... Base end portion 87 ... Tip portion 88 ... Projection portion 90 ... Left shroud 91 ... First opening portion 93 ... Right shroud 94 ... Second opening portion 96 ... Liquid flow path 98A, 98B ... Protector 100 ... Arrangement Space portion 101 ... first water passage portion 102 ... second water passage portion 104 ... partition plate portion 105 ... processing line

Claims (5)

A rotating shaft rotatably disposed in the casing;
An impeller disposed in the casing and connected to the rotating shaft,
The impeller is
A plurality of blades having a base end portion on the rotating shaft side and a tip end portion on the opposite side of the base end portion extending radially outward from the base end portion;
An opening is formed on the base end side of the blade, and a first shroud disposed on one end of the blade in a direction in which the rotation shaft extends;
A second shroud disposed at a distance from the first shroud on the other end side of the blade in the direction in which the rotating shaft extends;
The said blade is a fluid machine which has the protrusion part which protruded from the edge part by the side of the said opening part of a said 1st shroud.   The protrusion of the blade includes the entire base end portion from one end of the base end portion located on the first shroud side to the other end of the base end portion located on the second shroud side. Item 2. The fluid machine according to Item 1.   3. The fluid machine according to claim 1, wherein the casing includes a protector positioned on the first shroud side of the impeller at a distance from the protruding portion of the impeller.   A water passage formed between the protector and the edge of the opening includes a first portion extending in a radial direction of the impeller, and a first portion extending in an axial direction of the impeller continuously to the first portion. The fluid machine according to claim 3, wherein the fluid machine has a stepped structure having two parts and a third part extending in a radial direction of the impeller continuously to the second part.   The fluid machine according to claim 3 or 4, wherein a labyrinth is provided between the protector and the first shroud.

Images