Impeller, centrifugal pump

Abstract

To provide an open-type impeller which, when provided in a centrifugal pump, can increase the pump head and improve the efficiency.SOLUTION: An impeller (3) has a circular main plate (32), and a plurality of blades (33) arranged on a surface of the main plate (32). A side of the blades (33) opposite to the main plate (32) is opened. At least one of the blades (33) has at least one protrusion (40) in the side opposite to the main plate (32).SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an impeller provided in a centrifugal pump or the like for transferring a fluid.

Background Art

[0002] In recent years, attention has been focused on technologies that mimic and utilize the diverse functions of living organisms, so-called biomimetics. And Nature Technology (registered trademark) is known as an example of manufacturing that employs such biomimetic technologies in electrical products and the like.

[0003] As a pump for transferring a fluid, a centrifugal pump is known. A centrifugal pump includes a casing and an impeller disposed inside the casing. The impeller has a closed type in which blades are sandwiched between a main plate and a shroud, an open type in which the blades are exposed without a shroud, and the like.

[0004] Patent Document 1 discloses a configuration in a closed-type impeller in which a plurality of convex portions or a plurality of concave portions for generating turbulent flow in the flowing fluid are provided on the inner surface of the shroud to reduce flow separation and improve pump efficiency.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Since the technology disclosed in Patent Document 1 is premised on a configuration having a shroud, it cannot be applied to an open-type impeller without a shroud.

[0007] In addition, an open impeller is disposed inside a casing in which an opening for introducing a fluid is formed, with the blade side facing the opening. A discharge passage is provided on one side in the radial direction of the impeller in the casing. When the impeller is rotated, fluid is introduced into the casing through the opening, and the fluid is guided to the discharge passage through the gap between the impeller and the casing.

[0008] At this time, the exposed blades collide with the flow of the fluid heading toward the discharge passage, and large vortices called edge vortices are formed at the edges of the blades. The edge vortices increase fluid friction, deteriorate the flow, and reduce the head. In addition, the edge vortices cause energy loss and reduce the efficiency. Therefore, in the case of an open impeller, it is necessary to take measures against edge vortices.

[0009] One aspect of the present invention aims to realize an open impeller that can improve the head and efficiency when provided in a centrifugal pump.

Means for Solving the Problems

[0010] In order to solve the above problems, an impeller according to one aspect of the present invention includes a circular main plate and a plurality of blades disposed on the surface of the main plate. The opposite side of the plurality of blades from the main plate is open, and it is an impeller that transfers fluid by rotating in the front side in the rotation direction around a rotation axis. At least one of the plurality of blades has at least one convex portion protruding in the axial direction of the rotation axis from a top surface located on the opposite side of the blade from the main plate, and a portion of the convex portion located on the front side in the rotation direction has a shape that protrudes toward the front side in the rotation direction when viewed from the axial direction of the rotation axis. The impeller according to another aspect of the present invention includes a circular main board and a plurality of blades disposed on the surface of the main board. The opposite side of the plurality of blades from the main board is open, and it is an impeller that transfers fluid by rotating in the forward rotation direction around the rotation axis. At least one of the plurality of blades has at least one convex portion protruding in the axial direction of the rotation axis from the top surface located on the opposite side of the blade from the main board. The portion of the convex portion located on the rear side in the rotation direction is a surface that is convex toward the rear side in the rotation direction when viewed from the axial direction of the rotation axis. When viewed from the axial direction of the rotation axis, the central side end portion or the peripheral end portion in the radial direction of the portion of the convex portion located on the rear side in the rotation direction is located on the central side of the top surface in the circumferential direction of the rotation axis. The impeller according to still another aspect of the present invention includes a circular main board and a plurality of blades disposed on the surface of the main board. The opposite side of the plurality of blades from the main board is open. At least one of the plurality of blades has a plurality of convex portions on the opposite side of the main board. The plurality of convex portions are arranged along the extending direction of the blade, and the distance between the adjacent convex portions along the extending direction of the blade is shorter on the peripheral side of the blade than on the central side of the rotation of the blade. The impeller according to still another aspect of the present invention includes a circular main board and a plurality of blades disposed on the surface of the main board. The opposite side of the plurality of blades from the main board is open, and it is an impeller rotatable around the rotation axis. At least one of the plurality of blades has a plurality of convex portions on the opposite side of the main board. The plurality of convex portions are arranged along the extending direction of the blade. The convex portion located on the peripheral side in the radial direction of the rotation axis of the blade has a smaller area of the convex portion when rotationally projected onto the meridian plane than the convex portion located on the central side in the radial direction of the rotation axis of the blade. The impeller according to still another aspect of the present invention includes a circular main plate and a plurality of blades disposed on the surface of the main plate. The side of the plurality of blades opposite to the main plate is open, and the impeller is rotatable about a rotation axis. Among the plurality of blades, each of the blades adjacent to each other in the circumferential direction of the rotation axis has at least one convex portion on the side opposite to the main plate, and the convex portions provided on the plurality of blades adjacent to each other in the circumferential direction of the rotation axis are not located on the same circumference centered on the rotation axis. The impeller according to still another aspect of the present invention includes a circular main plate and a plurality of blades disposed on the surface of the main plate. The side of the plurality of blades opposite to the main plate is open, and the impeller is rotatable about a rotation axis. At least one of the plurality of blades has at least one convex portion protruding from the top surface located on the side opposite to the main plate to one side in the axial direction of the rotation axis, and a protection portion located at the center side end portion in the radial direction of the rotation axis and including a surface facing the center side in the radial direction of the rotation axis, and protruding to the one side in the axial direction more than the top surface. The protection portion has a width along the circumferential direction of the rotation axis larger than the width along the circumferential direction of the convex portion, or a height larger than the height of the convex portion.

Advantages of the Invention

[0011] According to one aspect of the present invention, when provided in a centrifugal pump, the head can be increased and the efficiency can be improved.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 8

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Figure 10

Figure 11

Figure 12

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Figure 14

Figure 15

Mode for Carrying Out the Invention

[0013] Hereinafter, embodiments according to one aspect of the present disclosure will be described with reference to the drawings. In this embodiment, an impeller mounted on a centrifugal pump for transferring a liquid as a fluid is illustrated, but it is not limited thereto, and the fluid may be a gas.

[0014] 〔Embodiment 1〕 Hereinafter, one embodiment of the present invention will be described in detail.

[0015] (1. Schematic Configuration of Centrifugal Pump) FIG. 1 is a perspective view of a pump unit 1 of a centrifugal pump including an impeller 3 according to the present embodiment. FIG. 2 is a partial cross-sectional view of the pump unit 1. In FIGS. 1 and 2, an arrow Y1 indicates the flow of fluid. The centrifugal pump includes a pump unit 1 that feeds the fluid shown in FIG. 1, and a motor unit (not shown) that drives the pump unit 1. The centrifugal pump sucks in fluid from an introduction opening 23 provided on the lower surface of the pump unit 1, and discharges the sucked fluid from a discharge opening 26a formed on the upper surface of the side portion of the pump unit 1. The motor unit is installed on the upper surface of the pump unit 1 on the side opposite to the lower surface where the introduction opening 23 is located.

[0016] The motor unit includes, for example, a motor case, a stator and a rotor housed inside the motor case. As shown in FIG. 1, the pump unit 1 includes a pump case 2 in which an introduction opening 23 and a discharge opening 26a are formed, and the motor case of the motor unit is fixed to the pump case 2. In the motor unit, the rotor rotates based on power supply to the stator, and the rotating shaft rotates together with the rotor. The rotating shaft is provided so as to protrude toward the pump unit 1 side, and transmits a rotational force to the pump unit 1 side.

[0017] (2. Configuration of Pump Unit) As shown in FIG. 2, the pump unit 1 includes the above-described pump case 2 and an impeller 3 housed inside the pump case 2. The pump case 2 includes a pump chamber 21 that rotatably houses the impeller 3. In FIG. 2, an axis passing through the center of rotation of the impeller 3 is indicated by a dashed-dotted line X. The impeller 3 has a substantially disk shape that is flat in the axial direction. Correspondingly, the pump chamber 21 also forms a substantially circular space that is flat in the axial direction.

[0018] The pump case 2 includes a shaft insertion hole 22 that communicates with the pump chamber 21. The tip of the rotating shaft protruding from the motor unit is inserted into the shaft insertion hole 22. The tip of the rotating shaft reaches the pump chamber 21, supports the impeller 3 disposed in the pump chamber 21, and is connected so as to rotate integrally with the impeller 3.

[0019] Further, the pump case 2 is provided with an introduction opening 23 for introducing fluid into the pump chamber 21 on the side axially opposite to the shaft insertion hole 22 of the pump chamber 21. The introduction opening 23 is formed in a partition wall 24 that partitions the side axially opposite to the shaft insertion hole 22 in the pump chamber 21. The impeller 3 is rotatably disposed in the pump chamber 21 with a gap from the partition wall 24 of the pump case 2. A gap G is formed between the impeller 3 and the partition wall 24. In the example of FIG. 2, the introduction opening 23 is coaxial with the shaft insertion hole 22 and is provided coaxially with the impeller 3.

[0020] Furthermore, the pump case 2 is provided with a discharge flow path 26 for discharging fluid from the pump chamber 21 on one side in the direction perpendicular to the axis of the pump chamber 21. The outlet of the discharge flow path 26 is the aforementioned discharge opening 26a, and the fluid is discharged from the pump unit 1 through the discharge opening 26a. Note that the discharge flow path 26 is connected via a device that receives the feeding of the fluid and piping (not shown) or the like.

[0021] (3. Schematic Configuration of Impeller) FIG. 3 is a bottom view of the impeller 3 according to the present embodiment. In other words, FIG. 3 is a plan view of the impeller 3 as viewed from the introduction opening 23 shown in FIG. 2. FIG. 4 is a perspective view of the impeller 3 according to the present embodiment. FIG. 4 shows a state where the bottom side is directed upward.

[0022] The impeller is made of, for example, a resin material. As shown in FIGS. 3 and 4, the impeller 3 has a circular main board 32 and, for example, eight impeller blades 33 of the same shape on the surface which is one surface in the thickness direction of the main board 32. The impeller 3 is a so-called open-type impeller in which the side opposite to the main board 32 of the plurality of impeller blades 33 is open.

[0023] The plurality of impeller blades 33 are arranged side by side at equal intervals in the circumferential direction. A groove flow path 34 for allowing fluid to pass through is formed between adjacent impeller blades 33. The plurality of impeller blades 33 are curved convexly in the counterclockwise direction indicated by the arrow Y2. The plurality of impeller blades 33 have a top surface 33a on the side opposite to the main board 32, and a plurality of convex portions 40 are formed on the top surface 33a. Details of the top surface 33a of the impeller blade 33 provided with the plurality of convex portions 40 will be described later.

[0024] At approximately the center of the main board 32, a D-shaped connecting hole 35 into which the tip of the rotating shaft of the motor unit described above is fitted is provided. Thus, when the rotating shaft rotates due to the rotational drive of the motor unit, the impeller 3 rotates integrally. In this embodiment, the connecting hole 35 is directly formed in the main board 32. However, for example, a cylindrical connecting member may be formed of a metal material or the like and assembled to the approximate center of the main board 32 so as not to rotate relative to each other.

[0025] (4. Operation of the Centrifugal Pump) When the impeller 3 rotates based on the rotational drive of the motor unit, as shown in FIGS. 1 and 2, the fluid is introduced into the pump chamber 21 from the introduction opening 23. The impeller 3 having the shape shown in FIGS. 3 and 4 rotates counterclockwise. The centrifugal force generated by the rotation of the impeller 3 is transmitted to the fluid introduced into the pump chamber 21, and the fluid is sent from the radially inner side (center side) to the radially outer side (peripheral side) of the impeller 3. The fluid sent toward the radially outer side enters the discharge flow path 26 through the gap G below the impeller 3 and is discharged from the discharge opening 26a.

[0026] Hereinafter, the flow of the fluid sent to the radially outer side through each groove flow path 34 is referred to as "centrifugal flow". Also, the flow of the fluid flowing from the gap G toward the discharge flow path 26 is referred to as "discharge flow".

[0027] (5. Detailed Configuration of the Top Surface of the Blades) The configuration of the top surface 33a of the blade 33 will be described with reference to FIGS. 3 and 4. As shown in FIGS. 3 and 4, each of the plurality of blades 33 has, for example, five convex portions 40 of the same shape on its respective top surface 33a.

[0028] As described above, when the impeller 3 rotates, the fluid introduced into the pump chamber 21 is sent radially outward through each groove flow path 34 based on the centrifugal force of the impeller 3 and is discharged from the discharge opening 26a through the discharge flow path 26. The flow of the fluid in the pump chamber 21 includes the centrifugal flow flowing through each groove flow path 34 and the discharge flow flowing toward the discharge flow path 26.

[0029] Since the impeller 3 is of an open type, the plurality of blades 33 rotate while colliding with the discharge flow in the gap G. Therefore, in a configuration where the convex portion 40 is not provided on the top surface 33a, an edge vortex, which is the large vortex described above, is generated in the gap G. The edge vortex disturbs the fluid flow, reduces the head, and also loses energy, thereby reducing the efficiency.

[0030] In the impeller 3, in order to suppress the generation of such an edge vortex, a plurality of convex portions 40 are provided on the top surface 33a. By providing the convex portion 40 on the top surface 33a, small vortices are generated around the convex portion, and the generation of the edge vortex is suppressed by these small vortices. In other words, by generating small vortices by the convex portion 40, the large edge vortex can be subdivided. Thereby, it is possible to suppress the reduction of the head and the energy loss due to the edge vortex generated in the gap G, and improve the head and the efficiency.

[0031] In addition, in the present embodiment, a configuration in which all of the plurality of blades 33 have a plurality of convex portions 40 on the top surface 33a is illustrated. However, any configuration may be used as long as at least one of the plurality of blades 33 has at least one convex portion 40 on the side opposite to the main plate 32 (on the top surface 33a). Thereby, the edge vortex can be subdivided as compared with a configuration in which the convex portion 40 is not provided on the top surface 33a.

[0032] However, preferably, all of the plurality of blades 33 have a plurality of convex portions 40 on the top surface 33a. As the number of the blades 33 provided with the convex portion 40 increases, and as the number of the convex portions 40 provided on one blade 33 increases, the edge vortex can be effectively subdivided.

[0033] Further, in a configuration in which a plurality of convex portions 40 are provided on the top surface 33a, preferably, as shown in FIGS. 3 and 4, the convex portions 40 are arranged in a plurality along the extending direction of the blade 33. By arranging them in this way, it is possible to suppress the generation of the edge vortex from the center side to the peripheral side of the rotation of the blade 33.

[0034] Further, although not shown in the drawings, the convex portion 40 is preferably provided at least on the peripheral side of the blade 33. This is because the speed of the blade 33 during rotation increases as it moves away from the center of rotation of the impeller, and the energy loss due to the edge vortex becomes large on the peripheral side of the blade 33 away from the center of rotation. By providing the convex portion 40 at least on the peripheral side of the blade 33, generation of the edge vortex can be suppressed on the peripheral side of the blade 33 where the energy loss is large, and the energy loss can be effectively suppressed.

[0035] (6. Preferred Shape of Convex Portion) As described above, regardless of its shape, the convex portion 40 provided on the top surface 33a can suppress the generation of the edge vortex compared to a configuration where the convex portion 40 is not provided on the top surface 33a. For example, as shown in FIGS. 3 and 4, the blade 33 has a front surface 33b located on the front side in the rotation direction (arrow Y2) and a rear surface 33c located on the rear side in the rotation direction. As the convex portion 40, even if it is a prismatic shape continuous with the front surface 33b and the rear surface 33c, the edge vortex can be subdivided. However, when the convex portion 40 is a prismatic shape having an edge, the vortex generated by the collision between the convex portion 40 and the discharge flow becomes large, and the energy lost is larger than that of a shape without an edge.

[0036] Therefore, in the present embodiment, as shown in FIGS. 3 and 4, the convex portion 40 is formed in a cylindrical shape. That is, the convex portion 40 has both a curved surface convex toward the front surface 33b and a curved surface convex toward the rear surface 33c when viewed from the direction of the axis passing through the center of rotation (viewed from the introduction opening 23 shown in FIG. 2). By adopting such a shape, the discharge flow colliding with the convex portion 40 easily passes along the curved surface of the convex portion 40, and the vortex generated by the collision between the convex portion 40 and the discharge flow is small (smaller than in the case of a prismatic shape), and the energy lost can be reduced.

[0037] In addition, in the present embodiment, the convex portion 40 is cylindrical, but the convex portion 40 may have a curved surface that protrudes toward at least one of the front surface 33b and the rear surface 33c. Thereby, compared with the configuration in which the convex portion 40 is prismatic, the energy loss due to the collision between the convex portion 40 and the discharge flow can be reduced.

[0038] That is, in the gap G, the discharge flow contacts the front surface 33b of the blade 33 on the upstream side of the discharge flow and contacts the rear surface 33c of the blade 33 on the downstream side of the discharge flow. Therefore, even if the convex portion 40 is provided so as to have a curved surface that protrudes toward either the front surface 33b or the rear surface 33c, it is possible to facilitate the discharge flow to pass through on the upstream side or the downstream side of the discharge flow.

[0039] However, preferably, it is a configuration having both a curved surface that protrudes toward the front surface 33b and a curved surface that protrudes toward the rear surface 33c. Thereby, in the gap G, it is possible to facilitate the discharge flow to pass through both on the upstream side and the downstream side of the discharge flow.

[0040] Furthermore, in the present embodiment, as shown in FIG. 4, the convex portion 40 is formed in a tapered shape in a direction away from the top surface 33a (a direction away from the main board 32). By adopting such a shape, the contact area between the top surface of the convex portion 40 and the discharge flow can be reduced. Thereby, the fluid friction resistance due to the shear flow generated between the top surface 33a of the blade 33 and the partition wall 24 can be reduced. As a result, the efficiency of the centrifugal pump can be further improved. Note that the tapered convex portion 40 may be a cone or a pyramid.

[0041] (7. Protective part) Furthermore, in the impeller 3, as shown in FIGS. 3 and 4, each of the plurality of blades 33 has a protective portion 36 that is larger than any of the convex portions 40 provided thereon at the center side of rotation on each top surface 33a. The protective portion 36 preferably has a width along the circumferential direction of a circle centered on the center of rotation that is larger than any of the convex portions 40. Also, the protective portion 36 preferably has a height that is higher than any of the convex portions. However, it may have the same height as the highest convex portion 40. The radially outer surface of the protective portion 36 is a surface along a circle centered on the center of rotation.

[0042] By providing such a protective portion 36, the convex portions 40 that are radially outside the protective portion 36 are prevented from being worn by the centrifugal flow that flows from the center side (radially inner side) of rotation toward the peripheral side (radially outer side). Thereby, the convex portions 40 can be protected and the life of the impeller 3 can be extended.

[0043] In addition, in the present embodiment, a configuration in which the protective portion 36 is provided on all the blades 33 provided with the convex portions 40 is illustrated. However, any configuration in which the protective portion 36 is provided on at least one of the blades 33 provided with the convex portions 40 may be used. Thereby, the life of the impeller 3 can be extended as compared with a configuration in which the protective portion 36 is not provided on any of the blades 33 provided with the convex portions 40. However, preferably, the protective portion 36 is provided on all the blades 33 provided with the convex portions 40.

[0044] 〔Embodiment 2〕 Another embodiment of the present invention will be described below. For convenience of explanation, members having the same functions as those described in the above embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

[0045] FIG. 5 is a bottom view of the impeller 3A according to the present embodiment and a partially enlarged view thereof. As shown in FIG. 5, in the impeller 3A according to the present embodiment, a plurality of convex portions 40A having the same shape are arranged on each top surface 33a of the plurality of blades 33 instead of the plurality of convex portions 40 having the same shape. This is different from the impeller 3.

[0046] The convex portion 40A is tapered and has a conical shape with a cut tip. And the top surface of the cut cone is offset toward the front side surface 33b in plan view. That is, in the convex portion 40A, the axis connecting the center of the bottom surface connected to the top surface 33a and the vertex on the side opposite to the bottom surface (in the case where the convex portion 40A is a cone) or the center of the top surface is inclined toward the front side in the rotation direction.

[0047] With such a shape, as shown in the figure of reference numeral 701 in FIG. 7, when the impeller 3 rotates, the peripheral surface of the convex portion 40A on the front side in the rotation direction of the convex portion 40A becomes a wall that rises at a steep angle toward the fluid. Therefore, the force for scraping the fluid in the impeller 3A becomes stronger, and the head of the pump can be increased. Such an impeller 3A is suitable for a pump with a large head. FIG. 7 is a diagram showing the relationship between the inclination of the peripheral surface of the convex portion on the front side in the rotation direction and the fluid coming toward the peripheral surface.

[0048] 〔Embodiment 3〕 Other embodiments of the present invention will be described below. For the sake of convenience of explanation, members having the same functions as the members described in the above embodiment are given the same reference numerals, and the description thereof will not be repeated.

[0049] FIG. 6 is a bottom view of the impeller 3B according to the present embodiment and a partially enlarged view thereof. As shown in FIG. 6, in the impeller 3B according to the present embodiment, a plurality of convex portions 40B having the same shape are arranged on the top surface 33a of each of the plurality of blades 33, instead of the plurality of convex portions 40 having the same shape. This is different from the impeller 3.

[0050] The convex portion 40B is tapered and has a conical shape with a cut tip. And the top surface of the cut cone is offset toward the rear side surface 33c in plan view. That is, in the convex portion 40B, the axis connecting the center of the bottom surface connected to the top surface 33a and the vertex on the side opposite to the bottom surface (in the case where the convex portion 40B is a cone) or the center of the top surface is inclined toward the rear side in the rotation direction.

[0051] By adopting such a shape, as shown in the diagram of reference numeral 702 in FIG. 7, when the impeller 3 rotates, the circumferential surface on the front side in the rotation direction at the convex portion 40B becomes a wall with a gentle slope with respect to the flow. Therefore, the vortices generated at the convex portion 40B are weak, and the energy loss due to the convex portion 40B can be reduced. Such an impeller 3B is suitable for a pump with a low head.

[0052] 〔Embodiment 4〕 Another embodiment of the present invention will be described below. For the sake of convenience of explanation, members having the same functions as those described in the above embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

[0053] FIG. 8 is a bottom view of the impeller 3C according to the present embodiment and a partially enlarged view thereof. As shown in FIG. 8, in the impeller 3C according to the present embodiment, a plurality of convex portions 40C are arranged on the top surfaces 33a of the plurality of blades 33 instead of the plurality of convex portions 40 having the same shape. This is different from the impeller 3.

[0054] The convex portion 40C is tapered and has a conical shape with a cut tip. And the top surface of the cut cone is biased in the extending direction of the blade 33 in plan view, that is, radially outward or radially inward of the blade 33, and the interval (distance) between the adjacent convex portions 40C in the extending direction of the blade 33 is varied. In the present embodiment, the interval between the adjacent convex portions 40C in the extending direction is shorter on the peripheral side of the blade 33 than on the central side of the rotation of the blade 33.

[0055] It is easier to break the edge vortices when the interval between the convex portions 40C is narrower than wider. Therefore, by adopting such a shape, the generation of edge vortices can be effectively suppressed on the peripheral side of the blade 33 where the energy loss is large, and the energy loss can be effectively suppressed.

[0056] In this embodiment, the direction of the tapered convex portion 40C is adjusted to vary the interval (distance) between adjacent convex portions 40C. However, the convex portions may be cylindrical, prismatic, or conical or pyramidal without an inclined axis, and the configuration may be such that the arrangement positions of the convex portions are changed to vary the interval.

[0057] FIG. 9 is a bottom view of a 3D impeller of a modified example according to this embodiment and a partially enlarged view thereof. As shown in FIG. 9, in the 3D impeller of the modified example, a plurality of convex portions 40D are arranged on the top surfaces 33a of the respective plurality of blades 33 instead of the plurality of convex portions 40 of the same shape. This is different from the impeller 3.

[0058] All of the plurality of convex portions 40D are tapered, have a conical shape with a cut tip, and the top surface is offset toward the center side (inner side in the radial direction) of the rotation of the blade 33 in a plan view. And, although the areas of the top surfaces of the plurality of convex portions 40D are all the same, the area of the bottom surface connected to the top surface 33a gradually decreases from the center side to the peripheral side of the rotation of the blade 33. Further, the interval (distance) between adjacent convex portions 40D in the extending direction of the blade 33 gradually narrows from the center side to the peripheral side of the rotation of the blade 33.

[0059] By adopting such a shape, on the peripheral side of the blade 33 where energy loss is large, the convex portions 40D are densely arranged to effectively suppress the generation of edge vortices, and the energy loss can be effectively suppressed.

[0060] [Embodiment 5] Another embodiment of the present invention will be described below. For the sake of convenience of explanation, members having the same functions as the members described in the above embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

[0061] FIG. 10 is a bottom view of an impeller 3E according to this embodiment and a partially enlarged view thereof. As shown in FIG. 10, in the impeller 3E according to this embodiment, a plurality of convex portions 40E are arranged on the top surfaces 33a of the respective plurality of blades 33 instead of the plurality of convex portions 40 of the same shape. This is different from the impeller 3.

[0062] The plurality of convex portions 40E are all tapered columnar shapes. And the plurality of convex portions 40E are formed smaller than the center side of the rotation of the blade 33 on the peripheral side of the blade 33.

[0063] More specifically, the plurality of convex portions 40E gradually become smaller from the center side to the peripheral side of the rotation of the blade 33. Specifically, the plurality of convex portions 40E have the same height, and the area of the bottom surface gradually becomes smaller from the center side to the peripheral side of the rotation of the blade 33. Further, the intervals (distances) between the adjacent convex portions 40E in the extending direction of the blade 33 are arranged so as to gradually become wider from the center side to the peripheral side of the rotation of the blade 33.

[0064] By adopting such a shape, in the blade 33, the Reynolds numbers on the peripheral side and the center side of the rotation can be made closer to each other. Thereby, the effect of suppressing the generation of edge vortices by the vortices generated by the convex portions 40E (the effect of subdivision) can be made uniform from the center side to the peripheral side of the rotation of the blade 33.

[0065] The Reynolds number is a dimensionless number that characterizes the flow generated by a convexity. The Reynolds number is obtained by the square root of the projected area of the convexity × the fluid velocity around the convexity ÷ the kinematic viscosity coefficient of the fluid. The fluid velocity around the convexity is approximated by the required discharge volume in the centrifugal pump ÷ (the diameter of the impeller × the distance of the gap G). Therefore, in other words, "the convex portion is small" means "the average width in the radial direction of the convex portion when rotationally projected onto the meridian plane is small", and strictly speaking, "the area of the convex portion rotationally projected onto the meridian plane including the height of the convex portion is small".

[0066] 〔Embodiment 6〕 Another embodiment of the present invention will be described below. For the sake of convenience of explanation, members having the same functions as the members described in the above embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

[0067] FIG. 11 is a bottom view of the impeller 3F according to the present embodiment and a partially enlarged view thereof. As shown in FIG. 11, in the impeller 3F according to the present embodiment, a plurality of convex portions 40 provided on a plurality of blades 33 adjacent to each other in the rotation direction are provided so as not to be located on the same circumference centered on the center of rotation. This is different from the impeller 3. In the present embodiment, the blades 33 having five convex portions 40 and the blades 33 having four convex portions 40 are alternately arranged in the circumferential direction.

[0068] When a plurality of convex portions 40 provided on the blades 33 adjacent to each other in the rotation direction are located on the same circumference centered on the center of rotation, the flow passing through between the convex portions 40 of the blade 33 located on the front side in the rotation direction also passes through between the convex portions 40 of the next blade 33 located on the rear side in the rotation direction. Therefore, the effect of the convex portion 40 contributing to the scraping of the fluid is small.

[0069] On the other hand, by adopting the above-described shape, the flow passing through between the convex portions 40 of the blade 33 located on the front side in the rotation direction collides with the convex portions 40 of the next blade 33 located on the rear side in the rotation direction. As a result, the effect of the convex portion 40 contributing to the scraping of the fluid is increased, and the head of the pump can be increased.

[0070] In addition, small vortices generated by the convex portions 40 of the blade located on the front side in the rotation direction are reversed by colliding with the convex portions 40 of the next blade 33 located on the rear side in the rotation direction. As a result, the effect of suppressing the generation of edge vortices by the small vortices generated around the convex portion 40 is improved, and the generation of edge vortices can be more effectively suppressed.

[0071] [Embodiment 7] Other embodiments of the present invention will be described below. For the sake of convenience of explanation, members having the same functions as the members described in the above embodiments are denoted by the same reference numerals, and the description thereof will not be repeated.

[0072] FIG. 12 is a bottom view of the impeller 3G according to the present embodiment and a partially enlarged view thereof. As shown in FIG. 12, in the impeller 3G according to the present embodiment, a groove portion 50 extending along the direction of the axis passing through the center of rotation is provided on the peripheral surface 33d of the plurality of blades 33. This is different from the impeller 3. The peripheral surface 33d is a surface located on the peripheral side of the blade 33.

[0073] In FIGS. 12 and 13, the arrow Y3 indicates the direction in which the fluid flows through the outer peripheral portion of the impeller 3 as viewed from the impeller 3. Y3 is opposite to the rotation direction of the impeller 3G indicated by the arrow Y2, and is also referred to as the reverse rotation direction.

[0074] With such a configuration, when the impeller 3 rotates, a vortex is generated in the groove portion 50, and the fluid friction between the peripheral surface 33d of the blade 33 and the fluid can be reduced by the vortex generated in the groove portion 50. As a result, the efficiency of the centrifugal pump can be further improved.

[0075] In the present embodiment, a configuration in which all of the plurality of blades 33 have the groove portion 50 on the peripheral surface 33d is illustrated, but a configuration in which at least one of the peripheral surfaces 33d of the plurality of blades 33 has the groove portion 50 may be used. Thereby, the fluid friction between the peripheral surface 33d of the blade 33 and the fluid can be reduced as compared with a configuration in which no groove portion 50 is provided on the peripheral surface 33d.

[0076] However, preferably, all of the plurality of blades 33 have the groove portion 50 on the peripheral surface 33d. As the number of the blades 33 provided with the groove portion 50 increases, the fluid friction between the peripheral surface 33d of the blade 33 and the fluid can be reduced.

[0077] Note that the groove portion 50 only needs to extend along the direction of the axis passing through the center of rotation, and does not necessarily reach the top surface 33a of the blade 33. Further, in FIGS. 12 and 13, a V-groove having a V-shaped cross section is illustrated as the groove portion 50, but a U-shaped or the like may be used.

[0078] (1. Preferred shape of groove portion) Here, the preferable shape of the groove portion 50 will be described with reference to FIGS. 12 and 14. As shown in the enlarged view of FIG. 12, the groove portion 50 has a first groove wall 50a on the front side and a second groove wall 50b on the rear side. The first groove wall 50a on the front side is the groove wall located on the front side in the rotation direction of the impeller 3G indicated by the arrow Y2. The second groove wall 50b on the rear side is the groove wall located on the rear side in the rotation direction of the impeller 3G indicated by the arrow Y2.

[0079] <Preferred condition 1> When the angle formed by the flow on the outer peripheral portion indicated by the reverse rotation direction Y3 and the first groove wall 50a is α, and the angle formed by the flow on the outer peripheral portion indicated by the reverse rotation direction Y3 and the second groove wall 50b is β, it is preferable that α > β. In other words, the angle α is the angle formed by the first groove wall 50a and the reverse rotation direction Y3, and the angle β is the angle formed by the second groove wall 50b and the reverse rotation direction Y3.

[0080] FIG. 14 is a diagram for explaining the relationship between the angle α, the angle β, and the turning component in the groove portion. As shown in the diagram of reference numeral 1401 in FIG. 14, in the groove portion 51 that satisfies the relationship of α > β, the turning component generated in the second groove wall 51b on the rear side is stronger than the turning component generated in the first groove wall 51a on the front side. Therefore, in such a groove portion 51, vortices are more likely to rotate.

[0081] On the other hand, in the groove portion 52 that satisfies the relationship of α ≤ β, the turning component generated in the second groove wall 52b on the rear side is equal to or less than the turning component generated in the first groove wall 52a on the front side. Therefore, in such a groove portion 52, vortices are less likely to rotate.

[0082] Therefore, by forming the groove portion 50 so as to satisfy the relationship of α > β like the groove portion 51, the effect of reducing fluid friction due to the vortices generated in the groove portion 50 can be enhanced.

[0083] <Preferred condition 2> Also, it is preferable that α ≤ 90 degrees. As shown in the figure of reference numeral 1402 in FIG. 14, in the groove portion 53 satisfying the relationship of α ≤ 90 degrees, the vortex generated in the groove portion 53 flows out along the first groove wall 53a in the flow direction of the fluid on the outer peripheral portion of the impeller indicated by the arrow Y3. Therefore, the energy loss due to the vortex generated in the groove portion 53 is small.

[0084] On the other hand, in the groove portion 54 satisfying the relationship of α > 90 degrees, the vortex generated in the groove portion 54 flows out along the first groove wall 54a in the direction opposite to the flow direction of the fluid on the outer peripheral portion of the impeller indicated by the arrow Y3. Therefore, the energy loss due to the vortex generated in the groove portion 54 is large.

[0085] Therefore, by forming the groove portion 50 so as to satisfy the relationship of α ≤ 90 degrees like the groove portion 53, the energy loss due to the vortex generated in the groove portion 50 can be suppressed.

[0086] <Preferred Condition 3> Also, it is preferable that β ≤ 90 degrees. As shown in the figure of reference numeral 1403 in FIG. 14, in the groove portion 55 satisfying the relationship of β ≤ 90 degrees, the swirling component generated in the second groove wall 55b on the rear surface side becomes large, and a strong vortex can be formed.

[0087] On the other hand, in the groove portion 56 satisfying the relationship of β > 90 degrees, the swirling component generated in the second groove wall 56b on the rear surface side becomes small, and it is difficult to form a vortex.

[0088] Therefore, by forming the groove portion 50 so as to satisfy the relationship of β ≤ 90 degrees like the groove portion 55, the effect of reducing fluid friction due to the vortex generated in the groove portion 50 can be enhanced.

[0089] FIG. 15 is a bottom view of the impeller 3H according to a modification of the present embodiment. As shown in FIG. 15, in the impeller 3H of the modification, a plurality of convex portions 40 and protective portions 36 are not provided on the top surfaces 33a of the plurality of blades 33. This point is different from the impeller 3G.

[0090] In such a configuration, the edge vortices cannot be subdivided, but the vortices generated in the groove portion 50 can reduce the fluid friction between the peripheral surface 33d of the blade 33 and the fluid. As a result, the efficiency of the centrifugal pump can be further improved.

[0091] 〔Summary〕 The impeller according to Embodiment 1 of the present invention has a circular main plate and a plurality of blades arranged on the surface of the main plate, and is an impeller in which the side of the plurality of blades opposite to the main plate is open, and at least one of the plurality of blades has at least one convex portion on the side opposite to the main plate.

[0092] According to the above configuration, small vortices are generated around the convex portion provided on the blade, and the generation of large edge vortices can be suppressed. As a result, when provided in a centrifugal pump, the decrease in head and energy loss due to large vortices generated in the gap can be suppressed, and the head and efficiency can be improved.

[0093] The impeller according to Embodiment 2 of the present invention is, in Embodiment 1, the plurality of blades have a front surface located on the front side in the rotation direction and a rear surface located on the rear side in the rotation direction, and the convex portion may have a curved surface that protrudes toward at least one of the front surface or the rear surface when viewed in the direction of the axis passing through the center of rotation.

[0094] According to the above configuration, the fluid that collides with the convex portion can easily pass along the curved surface, and the energy lost due to the collision between the convex portion and the fluid can be reduced.

[0095] The impeller according to Embodiment 3 of the present invention is, in Embodiment 1 or 2, the convex portion may be formed in a tapered shape in a direction away from the main plate.

[0096] According to the above configuration, the contact area between the top surface of the convex portion and the fluid can be reduced, and the fluid friction resistance due to the shear flow generated between the blade and the casing can be reduced. As a result, the performance of the pump can be further improved.

[0097] In the impeller according to Aspect 4 of the present invention, in the above Aspect 3, the axis connecting the center of the bottom surface and the vertex on the side opposite to the bottom surface or the center of the top surface of the convex portion may be inclined toward the front side in the rotation direction.

[0098] According to the above configuration, the peripheral surface of the convex portion on the front side in the rotation direction stands in the way of the fluid. Therefore, the force for scraping the fluid is strengthened, contributing to an increase in the head of the pump. It is suitable for a pump with a large head.

[0099] In the impeller according to Aspect 5 of the present invention, in the above Aspect 3, the axis connecting the center of the bottom surface and the vertex on the side opposite to the bottom surface or the center of the top surface of the convex portion may be inclined toward the rear side in the rotation direction.

[0100] According to the above configuration, the peripheral surface of the convex portion on the front side in the rotation direction quickly flows the fluid backward. Therefore, the force for scraping the fluid is weak, but the vortex generated in the convex portion is weak, and the energy loss due to the convex portion is small. It is suitable for a pump with a small head.

[0101] In the impeller according to Aspect 6 of the present invention, in any of the above Aspects 1 to 5, the convex portion may be provided at least on the peripheral edge side of the blade.

[0102] According to the above configuration, generation of a large vortex is suppressed on the peripheral edge side of the blade where energy loss is large. Thereby, energy loss can be effectively suppressed.

[0103] In the impeller according to Aspect 7 of the present invention, in any of the above Aspects 1 to 5, a plurality of the convex portions may be arranged along the extending direction of the blade.

[0104] According to the above configuration, generation of a large vortex is suppressed from the center side to the peripheral edge side of the rotation of the blade. Thereby, energy loss due to the tip vortex can be suppressed.

[0105] The impeller according to aspect 8 of the present invention, in the above aspect 7, the distance between the convex portions adjacent to each other in the extending direction of the blade may be shorter on the peripheral side of the blade than on the rotation center side of the blade.

[0106] According to the above configuration, convex portions are densely provided on the peripheral side of the blade where energy loss is large, and generation of large vortices is suppressed. Thereby, energy loss can be effectively suppressed.

[0107] The impeller according to aspect 9 of the present invention, in the above aspect 7 or 8, the convex portion may be smaller on the peripheral side of the blade than on the rotation center side of the blade.

[0108] According to the above configuration, the Reynolds number can be made closer on the peripheral side and the rotation center side of the blade. Thereby, the effect of suppressing the generation of large vortices (the effect of subdivision) can be made uniform from the rotation center side to the peripheral side of the blade.

[0109] The impeller according to aspect 10 of the present invention, in any one of the above aspects 1 to 9, at least one of the blades having the convex portion may have a protection portion larger than any of the convex portions provided on the blade on the rotation center side most in the blade.

[0110] According to the above configuration, the protection portion can suppress the convex portion from being worn by the centrifugal flow flowing from the radially inner side to the radially outer side, and can protect the convex portion.

[0111] The impeller according to aspect 11 of the present invention, in any one of the above aspects 1 to 10, the convex portion is provided on at least a plurality of the blades adjacent to each other in the rotation direction, and the convex portions provided on the plurality of the blades adjacent to each other in the rotation direction may be configured not to be located on the same circumference centered on the rotation center.

[0112] According to the above configuration, the flow passing through the convex portion of the blade located on the front side in the rotational direction collides with the blade located on the rear side in the rotational direction. Thereby, the convex portion contributes to the scraping out of water, and the pump efficiency can be increased. Further, the small vortex generated at the convex portion of the blade located on the front side in the rotational direction is reversed by colliding with the blade located on the rear side in the rotational direction. Thereby, the effect of suppressing the generation of large vortices by the small vortices generated around the convex portion is enhanced.

[0113] The impeller according to Aspect 12 of the present invention is, in any of the above Aspects 1 to 11, wherein the plurality of blades have a peripheral surface located on the peripheral side, and at least one of the plurality of blades may have a groove portion extending along the direction of the axis passing through the center of rotation on at least a part of the peripheral surface.

[0114] According to the above configuration, the fluid friction between the peripheral surface of the blade and the fluid can be reduced by the vortices generated in the groove portion provided on the peripheral surface of the blade. As a result, the performance of the pump can be further improved.

[0115] The impeller according to Aspect 13 of the present invention is, in the above Aspect 12, wherein the groove portion has a first groove wall on the front side surface side and a second groove wall on the rear side surface side, and when the angle formed by the first groove wall and the reverse rotation direction is α and the angle formed by the second groove wall and the reverse rotation direction is β, α>β may be satisfied.

[0116] According to the above configuration, the swirling component generated at the second groove wall on the rear side surface side becomes stronger than the swirling component generated at the first groove wall on the front side surface side, and vortices are likely to rotate in the groove portion. Thereby, the effect of reducing the fluid friction by the vortices generated in the groove portion can be enhanced.

[0117] The impeller according to Aspect 14 of the present invention is, in the above Aspect 12, wherein the groove portion has a first groove wall on the front side surface side, and when the angle formed by the first groove wall and the reverse rotation direction is α, α≦90 degrees may be satisfied.

[0118] According to the above configuration, the outflow angle of the vortex generated in the groove portion faces the flow direction of the fluid on the outer peripheral portion of the impeller, and the energy loss is small. Thereby, the energy loss due to the vortex generated in the groove portion can be suppressed.

[0119] In the impeller according to Embodiment 15 of the present invention, in the above Embodiment 12, the groove portion has a second groove wall on the rear surface side, and when the angle formed by the second groove wall and the reverse rotation direction is β, β may be β ≤ 90 degrees.

[0120] According to the above configuration, the swirling component generated on the second groove wall on the rear surface side becomes large, and a strong vortex can be formed. Thereby, the effect of reducing fluid friction due to the vortex generated in the groove portion can be enhanced.

[0121] The impeller according to Embodiment 16 of the present invention has a circular main plate and a plurality of blades arranged on the surface of the main plate, and is an impeller in which the opposite side of the plurality of blades from the main plate is open, and the plurality of blades have a peripheral surface located on the radially outer side, and at least one of the plurality of blades has a groove portion extending along the direction of the axis passing through the center of rotation on at least a part of the peripheral surface.

[0122] According to the above configuration, the fluid friction between the peripheral surface of the blade and the fluid can be reduced by the vortex generated in the groove portion provided on the peripheral surface of the blade. As a result, the performance of the pump can be further improved.

[0123] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. Furthermore, by combining the technical means disclosed in each embodiment, new technical features can be formed.

[0124] Note that this disclosure includes a technical idea focused on the small fin of tuna and the scale of carp. That is, this invention relates to bionics.

Explanation of Signs

[0125] 1 Pump section 2 Pump case 3, 3A, 3B, 3C, 3D, 3E, 3F, 3G, 3H Impellers 21 Pump chamber 22 Shaft insertion hole 23 Inlet opening 24 Partition wall 26 Discharge flow path 26a Discharge opening 32 Main board 33 Blade 33a Top surface 33b Front side surface 33c Rear side surface 33d Peripheral surface 34 Groove flow path 36 Protection part 40, 40A, 40B, 40C, 40D, 40E Protrusions 50 Groove part 50a First groove wall 50b Second groove wall Center of X rotation Y2 Rotation direction Y3 Reverse rotation direction

Claims

1. A impeller comprising a circular main board and a plurality of blades disposed on the surface of the main board, wherein the side of the plurality of blades opposite to the main board is open, and the impeller rotates forward in the rotational direction about a rotation axis to transfer fluid, at least one of the plurality of blades has at least one convex portion protruding in the axial direction of the rotation axis from a top surface located on the side of the blade opposite to the main board, a portion of the convex portion located on the front side in the rotational direction has a shape that is convex toward the front side in the rotational direction when viewed from the axial direction of the rotation axis. The impeller is as described above.

2. When viewed from the axial direction of the rotation axis, a central side end portion in the radial direction of the rotation axis or a peripheral side end portion in the radial direction of the rotation axis of the portion of the convex portion located on the front side in the rotational direction is located on the central side of the top surface in the circumferential direction of the rotation axis. The impeller according to claim 1.

3. A impeller comprising a circular main board and a plurality of blades disposed on the surface of the main board, wherein the side of the plurality of blades opposite to the main board is open, and the impeller rotates forward in the rotational direction about a rotation axis to transfer fluid, at least one of the plurality of blades has at least one convex portion protruding in the axial direction of the rotation axis from a top surface located on the side of the blade opposite to the main board, a portion of the convex portion located on the rear side in the rotational direction is a surface that is convex toward the rear side in the rotational direction when viewed from the axial direction of the rotation axis, When viewed from the axial direction of the rotation axis, a central side end portion in the radial direction of the rotation axis or a peripheral end portion in the radial direction of the rotation axis of the portion of the convex portion located on the rear side in the rotational direction is located on the central side of the top surface in the circumferential direction of the rotation axis. The impeller is as described above.

4. The impeller according to any one of claims 1 to 3, wherein the convex portion is formed in a tapered shape in a direction away from the main board.

5. The impeller according to claim 4, wherein an axis connecting the center of the bottom surface and the vertex on the side opposite to the bottom surface or the center of the top surface is inclined toward the front side in the rotational direction.

6. The impeller according to claim 4, wherein an axis connecting the center of the bottom surface and the vertex on the side opposite to the bottom surface or the center of the top surface is inclined toward the rear side in the rotational direction.

7. at least one of the plurality of blades has a plurality of the convex portions, The impeller according to any one of claims 1 to 6, wherein the plurality of convex portions are arranged along the extending direction of the blade.

8. A impeller comprising a circular main board and a plurality of blades disposed on a surface of the main board, wherein an opposite side of the plurality of blades from the main board is open, at least one of the plurality of blades has a plurality of convex portions on a side opposite to the main board, the plurality of convex portions are arranged along a direction in which the blade extends, an impeller in which a distance between the convex portions adjacent to each other in the extending direction of the blade is shorter on a peripheral side of the blade than on a central side of the rotation of the blade.

9. A impeller comprising a circular main board and a plurality of blades disposed on a surface of the main board, wherein an opposite side of the plurality of blades from the main board is open and the impeller is rotatable about a rotation axis, at least one of the plurality of blades has a plurality of convex portions on a side opposite to the main board, the plurality of convex portions are arranged along a direction in which the blade extends, a convex portion located on a peripheral side in a radial direction of the rotation axis of the blade has a smaller area of the convex portion when rotationally projected onto a meridian plane than a convex portion located on a central side in the radial direction of the rotation axis of the blade.

10. A impeller comprising a circular main board and a plurality of blades disposed on a surface of the main board, wherein an opposite side of the plurality of blades from the main board is open and the impeller is rotatable about a rotation axis, among the plurality of blades, each of the blades adjacent to each other in a circumferential direction of the rotation axis has at least one convex portion on a side opposite to the main board, the convex portions provided on the plurality of blades adjacent to each other in the circumferential direction of the rotation axis are not located on the same circumference centered on the rotation axis.

11. A impeller comprising a circular main board and a plurality of blades disposed on a surface of the main board, wherein an opposite side of the plurality of blades from the main board is open and the impeller is rotatable about a rotation axis, at least one of the plurality of blades, has at least one convex portion protruding from a top surface located on a side opposite to the main board to one side in an axial direction of the rotation axis, and a protective portion located at a central side end portion in a radial direction of the rotation axis and including a surface facing a central side in the radial direction of the rotation axis, the protective portion protruding more to the one side in the axial direction than the top surface, the protective portion has a width along a circumferential direction of the rotation axis larger than a width along the circumferential direction of the rotation axis of the convex portion, or a height larger than a height of the convex portion.

12. A pump case in which an introduction opening and a discharge opening are formed, The impeller according to any one of claims 1 to 11, which is housed in the pump case and discharges the fluid sucked from the introduction opening by rotational drive from the discharge opening; A centrifugal pump comprising: a motor that rotationally drives the impeller.

Images