Impeller and pump device

Abstract

To provide an impeller and a pump device that have high reliability without decreasing pump efficiency even if a balance weight is provided.SOLUTION: An impeller 42 used in a pump device 1 comprises: shrouds 52 and 53; a blade 54 provided on the shrouds 52 and 53, and arranged asymmetrically with respect to a rotation center; and a balance weight 55 inserted into the shrouds 52 and 53.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an impeller and a pump device for pumping wastewater or the like. [Background technology]

[0002] A pump device that is installed underwater and used to pump wastewater, etc., is a centrifugal pump with an impeller housed in a spiral-shaped casing. In such a submersible pump, for example, as the impeller rotates, wastewater is sucked in through a suction port provided on the bottom surface of the casing and discharged from a discharge port provided on the side surface of the casing.

[0003] Submersible pumps used to transport such sewage and the like are required to be designed to reliably discharge the sewage contained in them in order to prevent malfunctions caused by foreign matter contained in the sewage getting caught in the rotating shaft, impeller, etc.

[0004] For this reason, a configuration in which one blade is provided between two shrouds is known. However, when a single blade is provided, the blade shape is asymmetric, which causes imbalance during rotation and leads to vibrations, etc. Therefore, a technology is known in which a balance weight is provided on the impeller to achieve mechanical balance.

[0005] For example, there is a technique for providing a balance weight by thickening a portion of the outer surface of one of the shrouds (see, for example, Patent Document 1), and a technique for recessing a portion of the shroud, covering the recess with a lid provided with a balance weight, and fixing it with a bolt (see, for example, Patent Document 2). Also known are a technique for providing a balance weight inside the mouth of the impeller (see, for example, Patent Document 3), and a technique for placing a balance weight in a recess in the shroud, holding the balance weight with a lid, and fixing the lid to the shroud by hooking the claws of the lid into the recess in the shroud (see, for example, Patent Document 4). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5133026 [Patent Document 2] Patent No. 5044105 [Patent Document 3] Patent No. 5276370 [Patent Document 4] JP 2010-14047 A Summary of the Invention [Problem to be solved by the invention]

[0007] For example, as in Patent Document 1, if unevenness occurs on the outer surface of the shroud, even if an inclined surface is provided, it will cause fluid resistance, and there is a risk of casting defects due to uneven wall thickness. In the technology of Patent Document 2, a cover and bolts are required to fix the balance weight, which increases the number of parts and leads to increased costs, and there is also a risk that the balance weight will come off if the bolts loosen, causing a loss of mechanical balance of the impeller.

[0008] In the technology of Patent Document 3, the positioning hole is formed at a 90-degree angle to the inner diameter shape of the mouth, so a slide is required for the mold. Also, since the balance weight is positioned only from the outer periphery, there is a risk that the balance weight will move during molding, and the mechanical balance may not be achieved as designed.

[0009] The technology of Patent Document 4 requires a lid to fix the balance weight, which increases the number of parts and increases costs. In addition, there is a risk that the lid may come off, causing the balance weight to come off and deteriorating the mechanical balance.

[0010] As described above, providing a balance weight on an impeller leads to increased fluid resistance and an increase in the number of parts. Furthermore, if the balance weight falls off or becomes misaligned, the mechanical balance will subsequently deteriorate, reducing the reliability of the impeller.

[0011] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide an impeller and a pump device that are highly reliable and suppress a decrease in pump efficiency even when a balance weight is provided. [Means for solving the problem]

[0012] According to one aspect of the present invention, an impeller includes a shroud, blades provided on the shroud and arranged asymmetrically with respect to a center of rotation, and a balance weight inserted into the shroud.

[0013] According to one aspect of the present invention, a pump device includes the above-mentioned impeller and a casing that houses the impeller. Effect of the Invention

[0014] According to the present invention, even if a balance weight is provided, a decrease in pump efficiency is suppressed, and an impeller and a pump device having high reliability can be provided. [Brief description of the drawings]

[0015] [Figure 1] 1 is an explanatory diagram showing, in partial cross section, the configuration of a pump device according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a perspective view showing a configuration of an impeller of the pump device. [Diagram 3] FIG. [Figure 4] FIG. 2 is a cross-sectional perspective view showing the configuration of the blades and the front shroud of the impeller. [Diagram 5] FIG. [Figure 6] FIG. 4 is a plan view showing the configuration of a rear shroud of the impeller. [Figure 7] FIG. 4 is a plan view showing the configuration of a front shroud of the impeller. [Figure 8] 4A to 4C are explanatory views showing an example of a manufacturing method of the impeller. [Figure 9] 4 is a flowchart showing an example of a method for manufacturing the impeller. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, a pump device 1 and an impeller 42 according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an explanatory diagram showing a configuration of a pump device 1 according to an embodiment of the present invention in a partial cross section, FIG. 2 is a perspective view showing the configuration of an impeller 42 of the pump device 1, and FIG. 3 is a perspective view showing the configuration of the impeller 42 from a different direction than that of FIG. 2. FIG. 4 is a cross-sectional perspective view showing the configuration of a blade 54 and a front shroud 53 of the impeller 42. FIG. 5 is a cross-sectional view showing the configuration of the impeller 42. FIG. 6 is a plan view showing the configuration of the rear shroud 52 of the impeller 42, and FIG. 7 is a plan view showing the configuration of the front shroud 53. FIG. 8 is an explanatory diagram showing an example of the manufacturing method of the impeller 42 after the shrouds 52 and 53 have been molded, and FIG. 9 is a flow chart showing an example of a manufacturing method of the impeller 42.

[0017] 1, the pump device 1 includes a motor 10, a shaft sealing device 11, a pump 12, and a connecting pipe 13. Such a pump device 1 is a so-called submersible sewage pump that is installed in a sewage tank, a sewer system, or the like, and pumps sewage containing foreign matter (such as sewage).

[0018] The motor 10 includes a motor casing 21, a stator 22, a rotor 23, and a rotating shaft 24. The motor 10 also has a plurality of bearings 25 that rotatably support the rotating shaft 24, and a power cable 26 that connects the stator 22 to an external power source or the like. The motor casing 21 is formed in a cylindrical shape with both ends closed, and one end face is fixed to the shaft seal device 11 with a bolt or the like.

[0019] The stator 22 is fixed to the inner surface of the motor casing 21. The stator 22 is formed so as to be able to rotate the rotor 23 by power supplied via a power cable 26. The rotor 23 is fixed to the rotating shaft 24 so as to be able to rotate the rotating shaft 24 in accordance with the rotation of the rotor 23.

[0020] The rotating shaft 24 protrudes from one end side of the motor casing 21, and is rotatably supported by the motor casing 21 via a bearing or other bearing 25. The rotating shaft 24 extends from the motor casing 21 in the direction of gravity when the pump device 1 is placed on an installation surface.

[0021] The shaft seal device 11 includes a seal casing 30 and a mechanical seal 31. The shaft seal device 11 provides a liquid-tight partition between the motor 10, the pump 12, and the rotating shaft 24.

[0022] The seal casing 30 is formed so as to be capable of housing the mechanical seal 31 therein. Such a seal casing 30 is formed in a cylindrical shape with both ends closed, and an insertion hole 33 into which the rotating shaft 24 is inserted is formed on both end faces. The seal casing 30 also forms an oil chamber 34 therein that can be filled with lubricating oil for the mechanical seal 31. For example, the seal casing 30 is made up of two components separated in the axial direction, and the oil chamber 34 is formed therein by assembling them together.

[0023] The mechanical seal 31 seals the gap between the seal casing 30 and the rotating shaft 24, thereby preventing the infiltration of sewage from the pump 12 and the infiltration of lubricating oil into the motor 10.

[0024] The pump 12 includes a casing 41 and an impeller 42. The casing 41 is a spiral casing that houses the impeller 42 therein, and defines a pump chamber 43 therein. The casing 41 is made up of a plurality of components, and the pump chamber 43 is defined therein by assembling the components.

[0025] The casing 41 includes a plurality of legs 48 for mounting the pump device 1 on an installation surface. The casing 41 also includes a suction opening 49 provided on the bottom surface and between the plurality of legs 48, and a discharge opening 50 provided on a part of the side surface. The casing 41 houses the impeller 42.

[0026] The suction opening 49 is formed to have approximately the same diameter as a suction port 58 (described later) of the impeller 42. The suction opening 49 may have a liner ring that rotatably supports the impeller 42.

[0027] The discharge opening 50 is formed such that its aperture (discharge diameter) allows passage of foreign matter having a particle size that can pass through the impeller 42. Specifically, the aperture of the discharge opening 50 is formed to be substantially the same diameter as foreign matter of a predetermined particle size that can pass through the impeller 42. Here, foreign matter of a predetermined particle size that can pass through the impeller 42 is, for example, a spherical solid object having the same diameter (predetermined particle size) as the aperture (discharge diameter) of the discharge opening 50 of the pump device 1.

[0028] 1 to 7, the impeller 42 is a closed non-clog impeller that is formed to be able to pass foreign matter of a predetermined particle size. Such an impeller 42 includes a back shroud 52 arranged on the shaft seal device 11 side, a front shroud 53 arranged opposite the back shroud 52 and arranged on the suction opening 49 side, and vanes 54 provided between these shrouds 52, 53. The impeller 42 also includes a balance weight 55 insert-molded inside at least one of the back shroud 52 and the front shroud 53.

[0029] The impeller 42 also has a suction port 58 provided in the front shroud 53 for sucking in a fluid, and a discharge port 59 formed by the rear shroud 52, the front shroud 53, and the blades 54 for discharging the sucked in fluid. In this impeller 42, the rear shroud 52, the front shroud 53, and the blades 54 are molded from a resin material. The rear shroud 52, the front shroud 53, and the blades 54 may be formed from an elastomer.

[0030] The resin material constituting the impeller 42 is, for example, a polyamide resin. The polyamide resin is preferably a low water-absorbent polyamide resin having more than 6 carbon atoms in one unit. The polyamide resin is preferably a semi-aromatic polyamide resin.

[0031] The rear shroud 52 is formed in a disk shape. An insertion hole 52a having a key groove into which the rotating shaft 24 can be inserted is formed at the center of the rear shroud 52. Note that the insertion hole 52a can, for example, be formed by inserting an insert member into the rear shroud 52, into which the rotating shaft 24 can be firmly fixed and in which a key groove is formed for improving strength, and into which the rotating shaft 24 can be fixed. When the impeller 42 is fixed to the rotating shaft 24, the rear shroud 52 is located above the front shroud 53 in the direction of gravity.

[0032] The front shroud 53 is formed in an annular plate shape. The front shroud 53 has an inlet 58 formed at its center. The inlet 58 protrudes, for example, in a cylindrical shape from the front surface side of the front shroud 53. The rear shroud 52 and the front shroud 53 are formed in a plate shape extending in a direction perpendicular to the axial direction along the center of rotation, or extending in a direction substantially perpendicular to the axial direction so as to be slightly inclined in the direction perpendicular to the axial direction.

[0033] The blade 54 is provided integrally between the rear shroud 52 and the front shroud 53. The blade 54 is provided asymmetrically with respect to the rotation center of the impeller 42. That is, the blade 54 is provided integrally on the mutually opposing surfaces of the rear shroud 52 and the front shroud 53 in the direction along the rotation shaft 24, and is arranged asymmetrically with respect to the rotation shaft 24. As shown in FIG. 2 and FIG. 3, the blade 54 includes a first blade 61, a second blade 62, and a third blade 63. The blade 54 also constitutes a connecting wall 64 that connects one end side of the first blade 61, an end portion of the second blade 62 on the suction port 58 side, and an end portion of the third blade 63 on the suction port 58 side.

[0034] For example, the first blade 61, the second blade 62, and the third blade 63 are curved in the longitudinal direction with different radii of curvature and extend from the radial direction toward the outer circumferential edge of the shrouds 52, 53. In addition, for example, the first blade 61, the second blade 62, and the third blade 63 are formed to have the same thickness.

[0035] One end (connecting wall 64) of the first blade 61 is disposed on the center side of the shrouds 52, 53 and on the periphery of the suction port 58 of the front shroud 53, and the other end is disposed on the outer periphery of the shrouds 52, 53. More specifically, the first blade 61 is disposed on the periphery of the suction port 58 from one end toward the center, and the portion from the center to the other end moves away from the suction port 58 and curves with a predetermined radius of curvature to extend to the outer periphery of the shrouds 52, 53. The first blade 61 is integrally formed with the second blade 62 and the third blade 63 by the connecting wall 64 formed by the end on one side.

[0036] The second blade 62 has one end on the suction port 58 side integrally formed with the first blade 61 on the suction port 58 side. The second blade 62 is provided between the suction port 58 and the first blade 61 with a gap between the first blade 61 and the second blade 62, and extends from the suction port 58 toward the outer circumferential edge side of the shrouds 52, 53. The second blade 62 has an end on the outer circumferential edge side of the shrouds 52, 53 spaced apart from the outer circumferential edge of the shrouds 52, 53. As a specific example, the second blade 62 is provided branching off from the inner circumferential surface of the connecting wall 64, in other words, from the inner circumferential surface on the central side of one end side of the first blade 61. The end of the second blade 62 on the first blade 61 side is disposed on the periphery of the suction port 58, and the other end side from the central side is away from the suction port 58 and curved with a predetermined radius of curvature. The second blade 62 is disposed opposite a part of the first blade 61 and an inner peripheral surface of the first blade 61 at a predetermined distance, with one end being integral with the first blade 61 and the other end being spaced apart from the first blade 61. The second blade 62 is disposed opposite the first blade 61 so that the internal flow path from the suction port 58 inside the impeller 42 changes at an approximately constant rate.

[0037] The third blade 63 is formed in an asymmetric shape with respect to each of the first blade 61 and the second blade 62. The third blade 63 is provided branching off from an end of the connecting wall 64, in other words, from the outer peripheral surface side of the end of the first blade 61 on the suction port 58 side. The third blade 63 extends from the suction port 58 toward the outer peripheral edge side of the shrouds 52, 53, and the end on the outer peripheral edge side of the shrouds 52, 53 is separated from the outer peripheral edge of the shrouds 52, 53.

[0038] The connecting wall 64 is provided between the rear shroud 52 and the front shroud 53, radially facing the third blade 63, and is constituted by the end portion of the first blade 61 on the suction port 58 side. The connecting wall 64 connects the first blade 61, the end portion of the second blade 62 on the suction port 58 side, and the end portion of the third blade 63 on the suction port 58 side along the edge of the suction port 58. In other words, the connecting wall 64 forms one flow path for the water sucked from the suction port 58 from between the ends of the second blade 62 and the third blade 63 on the suction port 58 side toward the outer circumferential edge of the shrouds 52, 53.

[0039] In the impeller 42 thus configured, the end of the third blade 63 on the suction port 58 side and the end of the second blade 62 on the suction port 58 side are integrally formed with the end side (connecting wall 64) of the first blade 61. With this configuration, the impeller 42 forms a flow path from the suction port 58 through the inner peripheral surface of one end side (connecting wall 64) of the first blade 61 and between the end of the third blade 63 toward the discharge port 59, and pumps water through the outer peripheral surface of the first blade 61 and the outer peripheral surface of the third blade 63 during rotation. That is, the impeller 42 configures a so-called 1.5-blade non-clog impeller with the first blade 61 and the third blade 63. In addition, the second blade 62 of the impeller 42 keeps the amount of change in the flow path cross-sectional area of ​​the flow path from the suction port 58 to the discharge port 59 approximately constant, suppressing excessive change in the flow path cross-sectional area.

[0040] The balance weight 55 is insert-molded into at least one of the rear shroud 52 and the front shroud 53 to improve the mechanical balance of the impeller 42. Specifically, the balance weight 55 is inserted into a portion of the rear shroud 52 and the front shroud 53 extending along a direction perpendicular or substantially perpendicular to the axial direction of the rear shroud 52 and the front shroud 53. The balance weight 55 is covered with a resin material forming the rear shroud 52 and the front shroud 53 into which it is inserted, and is held inside the rear shroud 52 and the front shroud 53. For example, the balance weight 55 is made of a material having a higher specific gravity than the material forming the rear shroud 52 and the front shroud 53. Specifically, when the impeller 42 is a non-clog impeller and is configured to use one blade 54, the impeller 42 has an asymmetric shape with respect to the rotation axis 24, and the mechanical balance is located at a position shifted from the center of rotation. For this reason, the balance weight 55 adjusts the mechanical balance of the impeller 42 so that the mechanical balance displaced from the center of rotation by the blades 54 becomes the center of rotation or approaches the center of rotation. For this reason, the number, position, shape, weight, etc. of the balance weights 55 are appropriately set according to the shape and material of the blades 54. In this embodiment, an example in which the balance weights 55 are provided on both the rear shroud 52 and the front shroud 53 will be described.

[0041] The balance weight 55 is integrally provided inside the rear shroud 52 and the front shroud 53, for example, by insert molding. The balance weight 55 is formed, for example, in a fan-shaped plate shape. For example, the balance weight 55 is formed of a metal material. Two or more, preferably three or more, positioning holes 551 are formed in the balance weight 55. The positioning holes 551 are, for example, through holes penetrating the balance weight 55. Note that the positioning holes 551 are preferably through holes, but for example, the positioning holes 551 may be bottomed holes. For example, when the positioning holes 551 are bottomed holes, the positioning holes 551 are provided on both main surfaces of the balance weight 55, and preferably, one or more positioning holes 551 are provided on one main surface side of the balance weight 55, and two or more positioning holes 551 are provided on the other main surface side of the balance weight 55. In this embodiment, an example will be described in which the balance weight 55 has three positioning holes 551 that are through holes.

[0042] In this embodiment, since the weight of the blades 54 of the impeller 42 is the heaviest at the connecting wall 64, for example, the balance weight 55 is disposed at a symmetrical or approximately symmetrical position to the connecting wall 64 around the central axis of the impeller 42.

[0043] 2 to 4, 6 and 7, the impeller 42 has openings 521 and 531, the same number as the positioning holes 551, and larger in diameter than the inner diameter of the positioning holes 551, at positions facing the positioning holes 551 of the rear shroud 52 and the front shroud 53. The openings 521 and 531 formed in the rear shroud 52 and the front shroud 53 are provided, for example, on both main surfaces of the rear shroud 52 and the front shroud 53. For example, when three positioning holes 551 are provided in the balance weight 55, one opening 521 and 531 are formed in one main surface of each of the shrouds 52 and 53, and two openings 521 and 531 are formed in the other main surface of each of the shrouds 52 and 53. Also, for example, of the three positioning holes 551 of the balance weight 55, the two openings 521 and 531 facing the positioning holes 551 at both ends are formed in the same main surface of each of the shrouds 52 and 53. The openings 521, 531 formed in the shrouds 52, 53 may be configured to be closed by attaching a cap or filling with a caulking agent.

[0044] For example, as shown in FIG. 8, in the positioning hole 551, the tip 202 of the positioning pin 200 that positions the balance weight 55 during the manufacture of the impeller 42 is placed, and the body 201 of the positioning pin 200 forms openings 521, 531 in each shroud 52, 53.

[0045] Next, a manufacturing method of the impeller 42 configured as above will be described with reference to Figures 8 and 9. In this embodiment, an example will be described in which the impeller 42 is manufactured by welding together a main plate 101 on which the rear shroud 52 and the blades 54 are integrally injection molded, and a sub-plate 102 on which the front shroud 53 is injection molded separately from the blades 54.

[0046] First, in preparation for injection molding, balance weights 55 are placed in a mold (step ST1). As a specific example, when molding the main plate 101 which is a molded product of the rear shroud 52 and the blades 54, and the sub-plate 102 which is a molded product of the front shroud 53, the balance weights 55 are placed and held in the mold so that the balance weights 55 are placed at predetermined positions of each shroud 52.

[0047] For example, the balance weight 55 is held by a positioning pin 200 provided in a mold. The positioning pin 200 has, for example, a cylindrical body 201 and a cylindrical tip 202 having a smaller diameter than the body 201 and the same diameter or slightly smaller diameter than the positioning hole 551 of the balance weight 55. The tip 202 of the positioning pin 200 is inserted into two positioning holes 551 from one main surface side of the balance weight 55, and the tip 202 of the positioning pin 200 is inserted into one positioning hole 551 from the other main surface side.

[0048] Also, for example, the end face of the positioning pin 200 on which the tip portion 202 of the body portion 201 is provided abuts against the main surface around the positioning hole 551 of the balance weight 55. As a result, the balance weight 55 is held by the positioning pin 200 from both main surface sides at a predetermined position in the mold. In addition, the positioning holes 551 at both ends in the arrangement direction of the three positioning holes 551 are held by the positioning pin 200 from one main surface side of each of the shrouds 52 and 53, and the central positioning hole 551 in the arrangement direction of the three positioning holes 551 is held by the positioning pin 200 from the other main surface side of each of the shrouds 52 and 53. As a result, the balance weight 55 is held by the positioning pin 200 in three axial directions perpendicular to each other in the mold, specifically, in the thickness direction of the balance weight 55 and the radial direction of the positioning hole 551. It is sufficient that the balance weight 55 has at least two positioning holes 551. In order to insert-mold the balance weight 55 inside the shrouds 52 and 53, at least two positioning pins 200 are inserted into the positioning holes 551 from one main surface side of the balance weight 55, thereby enabling the balance weight 55 to be held within the mold.

[0049] Next, the mold is clamped (step ST2), and resin is injected into the mold to perform injection molding of the main plate 101 and the sub-plate 102 (step ST3). The main plate 101 and the sub-plate 102 are manufactured in separate molds, for example, in separate processes. After injection molding, the molded main plate 101 and the sub-plate 102 are cooled (step ST4), the mold is opened (step ST5), and the main plate 101 and the sub-plate 102 are removed from the mold. When the mold is opened and the main plate 101 and the sub-plate 102 are released from the mold, the positioning pin 200 is retracted from each of the shrouds 52 and 53, as shown in FIG. 8. Here, resin is not supplied to the position where the body 201 of the positioning pin 200 that held the balance weight 55 is located, and therefore openings 521 and 531 are formed in each of the shrouds 52 and 53.

[0050] Through these steps, the main plate 101 and the sub-plate 102 are formed with the balance weights 55 arranged at predetermined positions on the rear shroud 52 and the front shroud 53. Next, the blades 54 of the main plate 101 and the front shroud 53 (sub-plate 102) are welded together by a method such as ultrasonic welding (step ST6). Through these steps, the impeller 42 is manufactured.

[0051] According to the impeller 42 and pump device 1 configured in this manner, the impeller 42 is made of a resin material, and the mechanical balance deviation caused by the asymmetrically arranged blades 54 can be eliminated by the balance weights 55 inserted into the rear shroud 52 and the front shroud 53. This enables the impeller 42 to have an improved mechanical balance, and the load applied to the bearing 25 due to the imbalance, such as a radial load, can be reduced, so that the pump device 1 can improve the life of the bearing 25.

[0052] Moreover, the impeller 42 is configured such that the balance weight 55 is disposed inside the rear shroud 52 and the front shroud 53 by insert molding. Therefore, no unevenness due to the balance weight 55 is generated on the main surfaces of the rear shroud 52 and the front shroud 53. Therefore, the impeller 42 can suppress the occurrence of fluid loss due to the unevenness of the rear shroud 52 and the front shroud 53. More specifically, the only unevenness generated in order to place the balance weight 55 on the rear shroud 52 and the front shroud 53 is the positioning openings 521, 531 and the positioning hole 551 for the balance weight 55. This reduces the effect of reducing fluid loss, and makes it possible to minimize the fluid loss of the impeller 42.

[0053] In addition, in order to further reduce the effect of openings 521 and 531, the impeller 42 can eliminate the effect of openings 521 and 531 with a simple configuration by attaching caps to the openings 521 and 531 or filling them with caulking agent, and can also eliminate fluid loss due to the balance weight 55.

[0054] As described above, in the pump device 1, by inserting the balance weight 55 into at least one of the rear shroud 52 and the front shroud 53 in order to balance the impeller 42, an increase in fluid resistance caused by the balance weight 55 can be prevented, and a decrease in pump efficiency can be suppressed.

[0055] Furthermore, by making the inner diameter of the openings of the rear shroud 52 and the front shroud 53 (i.e., the outer diameter of the body 201 of the positioning pin 200) larger than the inner diameter of the positioning hole 551 of the balance weight 55, the balance weight 55 can be pressed and held from both main surfaces. Since the balance weight 55 can be held firmly, it is possible to prevent the balance weight 55 from moving within the mold during injection molding, and the balance weight 55 can be positioned at a predetermined position. Therefore, it is possible to prevent the mechanical balance of the impeller 42 from deviating from the design value due to misalignment of the balance weight 55, and the impeller 42 can be molded with high precision.

[0056] Also, three positioning holes 551 are formed in the balance weight 55, and the positioning holes 551 at both ends and the central positioning hole 551 are held by positioning pins 200 from different main surface sides of the balance weight 55. This makes it possible to sandwich the balance weight 55 and stably hold its posture. Therefore, with as few positioning holes 551 and openings 521, 531 as possible, the balance weight 55 can be positioned in a more predetermined position.

[0057] In addition, since the impeller 42 is configured such that the balance weight 55 is inserted into the rear shroud 52 and the front shroud 53, even if a design change is made to the balance weight 55, the shape of the balance weight 55 can be changed without requiring modification of the mold.

[0058] Moreover, by making the inner diameter of the openings 521, 531 larger than the inner diameter of the positioning hole 551 of the balance weight 55, a part of the balance weight 55 can be visually confirmed from the openings 521, 531. Therefore, the impeller 42 can be visually inspected for forgetting to place the balance weight 55 during manufacture.

[0059] Furthermore, because the position of balance weight 55 provided on impeller 42 can be identified by openings 521 and 531, it becomes easy to separate balance weight 55 from the resin molded product when impeller 42 is disposed of.

[0060] In addition, since the balance weight 55 is configured to be insert-molded into at least one of the rear shroud 52 and the front shroud 53, no lid, bolts, or the like is required for fixing the balance weight 55 to the rear shroud 52 and the front shroud 53. Therefore, the impeller 42 can prevent an increase in the number of parts and an increase in the manufacturing process, thereby reducing the manufacturing cost.

[0061] Furthermore, the balance weight 55 is covered with the resin material forming the rear shroud 52 and the front shroud 53. Therefore, the balance weight 55 does not come off the rear shroud 52 and the front shroud 53, and does not move within the rear shroud 52 and the front shroud 53. This prevents the impeller 42 from being degraded in reliability due to the balance weight 55 coming off or moving, and also prevents subsequent mechanical imbalance from occurring due to the balance weight 55 coming off or moving. This allows the pump device 1 to achieve high reliability.

[0062] As described above, the impeller 42 and pump device 1 according to one embodiment of the present invention have high reliability and suppress a decrease in pump efficiency even when the balance weights 55 are provided by inserting the balance weights 55 into the rear shroud 52 and the front shroud 53.

[0063] The present invention is not limited to the above-described embodiment. For example, in the above-described example, the openings 521, 531 of the shrouds 52, 53 and the positioning hole 551 of the balance weight 55 are described as being round holes, but the present invention is not limited to this. For example, the openings 521, 531 of the shrouds 52, 53 and the positioning hole 551 of the balance weight 55 may be square holes or elliptical holes. In addition, the positioning hole 551 of the balance weight 55 is described as being a through hole and a bottomed hole, but the present invention is not limited to this. Any one of the positioning holes 551 may be a through hole and the remaining through holes may be bottomed holes.

[0064] In addition, the balance weight 55 is described as being provided with a positioning hole 551 for positioning during molding, but the positioning is not limited to a hole, and may be, for example, uneven. In addition, when the balance weight 55 has a positioning convex portion, a part of the balance weight 55, for example, the positioning convex portion, may be exposed to the plane of the main surface of the shrouds 52 and 53. For example, when a bottomed hole serving as a positioning hole is molded in the balance weight 55 by press processing, the other main surface side becomes a convex portion while the concave portion of the hole on one main surface side. In this case, in molding the shrouds 52 and 53 into which the balance weight 55 is inserted, for example, resin is injection molded in a state in which the tip of the convex portion of the balance weight 55 contacts the inner wall of the mold when the mold is closed. The plane around the convex portion is covered with resin, while the tip of the convex portion is not covered with resin, and a part of the balance weight 55 is exposed to the plane of the main surface of the shrouds 52 and 53. This allows the convex portion of the balance weight 55 to be visually recognized. In addition, since the convex portion of the balance weight 55 abuts against the shrouds 52, 53 around the convex portion in a direction perpendicular to the axial direction of the shrouds 52, 53, i.e., in a planar direction or approximately planar direction of the main surfaces of the shrouds 52, 53 including the radial and circumferential directions of the shrouds 52, 53, movement of the balance weight 55 in a planar direction can be further prevented.

[0065] Also, the number, shape, arrangement and material of the balance weights 55 are not limited to the above example, and can be set as appropriate. Also, the example in which the balance weight 55 is provided on at least one of the rear shroud 52 and the front shroud 53 by insert molding has been described, but the present invention is not limited to this. For example, the balance weight 55 may be made of a resin material having a higher specific gravity than the resin material forming the rear shroud 52, the front shroud 53 and the blades 54, and may be configured to be provided on at least one of the rear shroud 52 and the front shroud 53 by two-color molding.

[0066] Further, the impeller 42 has the blade 54 having the first blade 61, the second blade 62, and the third blade 63, but is not limited thereto. That is, the impeller 42 may have the blades 54 arranged asymmetrically, the mechanical balance of the structure excluding the balance weight 55 may be shifted from the rotation center of the impeller 42 due to the blades 54, and the balance weight 55 may adjust the shift in the mechanical balance of the impeller 42. For this reason, the blade 54 of the impeller 42 may be formed by the first blade 61 and the second blade 62 without the third blade 63, or may be a single blade curved at a predetermined curvature without the second blade 62 and the third blade 63. The thickness (width) of the blade 54 can be appropriately set according to the strength, etc., and may be formed to have a uniform thickness, or may be set to a thickness that varies depending on the position.

[0067] Further, the impeller 42 has been described as having a configuration including a rear shroud 52, a front shroud 53, and blades 54, but is not limited to this, and may be a so-called semi-open type that has a rear shroud 52 and blades 54 but does not have a front shroud 53.

[0068] In addition, the impeller 42 has been described as having three positioning holes 551 in the balance weight 55 and three openings 521, 531 in each of the shrouds 52, 53, but the present invention is not limited to this, and the number of positioning holes 551 and openings 521, 531 can be appropriately set as long as they are multiple, preferably three or more. Also, the same positioning hole 551 may be configured to hold the balance weight 55 from both main surfaces with positioning pins 200. However, in order to stably hold the balance weight 55, it is preferable to hold the balance weight 55 from both sides with positioning pins 200 and to hold the balance weight 55 with two or more positioning pins 200 on at least one main surface. Also, in order to prevent the mold from becoming complicated and the number of openings 521, 531 from increasing in each of the shrouds 52, 53, it is more preferable that the number of positioning holes 551 and openings 521, 531 is three.

[0069] In the above example, the balance weight 55 is made of a material having a higher specific gravity than the material forming the rear shroud 52 and the front shroud 53, but the present invention is not limited to this. For example, the balance weight 55 may be made of a material having a lower specific gravity than the rear shroud 52 and the front shroud 53, and when the mechanical balance is shifted from the center of rotation of the impeller 42 by the blades 54, the balance weight 55 having a lower specific gravity than the material of each shroud 52 may be disposed at the position of the mechanical balance shifted by the blades 54 to adjust the mechanical balance of the entire impeller 42. In this way, the balance weight 55 is formed from a material having a different specific gravity from that of the rear shroud 52 and the front shroud 53, and by shifting the mechanical balance of the rear shroud 52 or the front shroud 53 from the center of rotation in at least one of the rear shroud 52 and the front shroud 53, it is possible to offset the mechanical balance shift in the shrouds 52, 53 and the mechanical balance shift caused by the blades 54, thereby adjusting the mechanical balance of the impeller 42.

[0070] That is, the present invention is not limited to the above-mentioned embodiment, and various modifications can be made in the implementation stage without departing from the gist of the invention. In addition, the embodiments may be implemented in appropriate combination, and in that case, the combined effect can be obtained. Furthermore, the above-mentioned embodiment includes various inventions, and various inventions can be extracted by combinations selected from the multiple components disclosed. For example, if the problem can be solved and the effect can be obtained even if some components are deleted from all the components shown in the embodiment, the configuration from which the components are deleted can be extracted as an invention. [Explanation of symbols]

[0071] REFERENCE SIGNS LIST 1...pump device, 10...motor, 11...shaft seal device, 12...pump, 13...connecting pipe, 21...motor casing, 22...stator, 23...rotor, 24...rotating shaft, 25...bearing, 26...power cable, 30...seal casing, 31...mechanical seal, 33...insertion hole, 34...oil chamber, 41...casing, 42...impeller, 43...pump chamber, 48...leg, 49...suction opening, 50...discharge opening , 52... rear shroud (shroud), 52a... insertion hole, 53... front shroud (shroud), 54... blade, 55... balance weight, 58... suction port, 59... discharge port, 61... first blade, 62... second blade, 63... third blade, 64... connecting wall, 101... main plate, 102... sub-plate, 200... positioning pin, 201... body, 202... tip, 521... opening, 531... opening, 551... positioning hole.

Claims

1. A resin plate-shaped shroud; A vane is provided along a rotation axis of the shroud and is arranged asymmetrically with respect to the rotation axis; a balance weight made of a material having a specific gravity different from that of the shroud and inserted into and held inside the shroud; An impeller comprising:

2. The balance weight has a plurality of holes, The impeller of claim 1 , wherein the shroud has a plurality of openings opposite the plurality of holes.

3. The plurality of holes is two or more, The impeller according to claim 2 , wherein the opening faces the hole on one main surface side of the shroud.

4. The impeller of claim 2 , wherein the opening is larger in diameter than the hole.

5. the plurality of holes is three or more; The impeller according to claim 2 , wherein the plurality of openings face one or more of the holes on one main surface side of the shroud and face two or more of the holes on the other main surface side of the shroud.

6. An impeller according to any one of claims 1 to 5; A casing that houses the impeller; A pump device comprising:

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