Impeller, pump device and method for manufacturing impeller

Abstract

To provide a small impeller which can secure a passage area, and to provide a pump device.SOLUTION: An impeller according to one embodiment of the invention includes: a shroud which extends intersecting with a direction of a rotation shaft; and blades each of which is disposed on one surface as seen in a first direction of the shroud, extends in a direction intersecting with the rotation shaft direction, and has a relief part, where a part at the shroud side is retreated in a direction away from the rotation shaft, at a rotation shaft side end part.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an impeller, a pump device, and a method for manufacturing an impeller. [Background technology]

[0002] As a means for pumping liquid, a pump device equipped with a motor and a pump driven by the motor is known. In such a pump device, the impeller housed in a pump chamber is rotated by the motor to increase the pressure of the liquid and pump it to the secondary side (see, for example, Patent Document 1). In an impeller in which parts such as a main plate, blades, and side plates are manufactured and integrally joined by laser welding or projection welding, it is necessary to design the impeller hub and the blades so that they do not interfere with each other, and the inlet diameter of the blades is restricted by the shape of the impeller hub. In recent years, there has been a demand for miniaturization of products, and it is desirable to shorten the axial length of the impeller, but it is difficult to ensure a sufficient flow passage area with the limited axial length and side plate length. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-61983 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide an impeller, a pump device, and a method for manufacturing an impeller that is small and capable of ensuring a large flow path area. [Means for solving the problem]

[0005] A pump device according to one aspect of the present invention includes a shroud extending in a direction intersecting with a rotation axis direction; an impeller including: a blade disposed on one surface of the shroud in the rotation axis direction, extending in a direction intersecting the rotation axis direction, and having a relief portion at an end portion on the rotation axis side where the shroud side is partially retracted in a direction away from the rotation axis; A rotating shaft fixed to the impeller; A pump casing that houses the impeller. The shroud includes a cylindrical impeller hub disposed around the rotating shaft, the end surface of the blade on the side of the rotation shaft has an inner end surface, and a relief surface inclined or curved in a direction away from the rotation shaft at a portion extending from an end portion of the inner end surface on the side of the shroud to the shroud, At least a portion of the blades has blade pieces that are inclined or curved with respect to the rotation axis direction and the extension direction or tangential direction of the shroud in a cross-sectional view, The relief surface is disposed at a position facing an outer surface of the impeller hub, The blade is configured to have a three-dimensional shape having a portion that is inclined or curved with respect to the rotation axis in a cross-sectional view taken along the rotation axis direction. The clearance surface is formed by a portion from the midpoint of the blade piece to the end portion on the first shroud side and an inner end face of the joining end piece. Effect of the Invention

[0006] According to the present invention, it is possible to provide an impeller, a pump device, and a method for manufacturing an impeller that are small and capable of ensuring a large flow path area. [Brief description of the drawings]

[0007] [Figure 1] 1 is a side view, partially in cross section, showing a configuration of a pump device according to a first embodiment of the present invention. [Diagram 2] FIG. [Diagram 3] FIG. 2 is a perspective view showing a configuration of an impeller of the pump device according to the embodiment. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6]FIG. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] FIG. [Figure 10] FIG. 4 is an explanatory diagram of design points of the inner end face of the impeller. [Figure 11] FIG. 4 is a cross-sectional view of an impeller as a comparative example. [Figure 12] FIG. 4 is a cross-sectional view of an impeller as a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] An impeller and a pump device according to an embodiment of the present invention will be described below with reference to Figs. 1 to 12. Fig. 1 is a side view showing the configuration of the pump device in partial cross section, and Fig. 2 is a side view of the pump device viewed from another direction. Fig. 3 is a perspective view of the impeller, and Figs. 4 and 5 are plan and bottom views of the impeller. Fig. 6 is a cross-sectional view of the impeller, and Figs. 7 and 8 are perspective views showing a part of the impeller. Fig. 9 is a perspective view of a blade. Fig. 10 is an explanatory diagram of the design points of the inner end face of the impeller, and Figs. 11 and 12 are cross-sectional views of an impeller as a comparative example. For the sake of explanation, the configuration is omitted appropriately in each figure.

[0009] 1, the pump device 1 is, for example, a multi-stage turbine pump. The pump device 1 includes a motor 11 and a one-stage or multi-stage pump section 12 having an impeller 30 connected to the motor 11. The pump device 1 is also connected to a control panel that houses an inverter and multiple control boards.

[0010] The motor 11 is connected to a control panel by a cable. The motor 11 is connected to a control board via multiple inverters, and the rotation speed is controlled by a control unit mounted on the control board.

[0011] The pump section 12 includes a rotating shaft 21 , a pump casing 22 , and an impeller 30 housed in the pump casing 22 .

[0012] The rotating shaft 21 (main shaft) is connected to the motor 11. The rotating shaft 21 is configured so that the impeller 30 of the pump section 12 can be fixed thereto. The rotating shaft 21 is journalled by a bearing member.

[0013] The pump casing 22 has a pump suction port and a pump discharge port, and houses a plurality of impellers 30. The pump casing 22 is made of, for example, stainless steel, and integrally comprises a small-diameter cylindrical suction section provided at the tip side of the rotating shaft 21, a housing section provided continuous with the suction section, and a cylindrical discharge section communicating with the outer periphery of the housing section and facing upward, thereby forming a predetermined flow path. A casing cover 23 is attached to the axial base end side of the pump casing 22. The motor 11 is fixed to the casing cover 23.

[0014] The impeller 30 is, for example, a closed-type pressed impeller. The impeller 30 includes a first shroud 31 which is a main plate, a second shroud 32 which is a side plate arranged opposite to the first shroud 31, and blades 33 disposed between the pair of shrouds 31, 32, and is formed to be able to pass a fluid.

[0015] The impeller 30 is a pressed impeller constructed by pressing a metal plate such as a steel plate to form a first shroud 31, a second shroud 32, and blades 33, and then joining the formed first shroud 31, second shroud 32, and blades 33 together by laser welding.

[0016] The impeller 30 is a three-dimensional impeller, and for example, the cross-sectional shape changes in the extension direction of the blades 33. For example, in the impeller 30, at least a part of the blades 33 has an extension direction or tangential direction in which a cross section along a first direction that is perpendicular to the extension direction of the blade and is the rotation axis direction is inclined with respect to the first direction and the extension direction or tangential direction of the shroud 31. In this embodiment, the extension direction of at least a part of the blades 33 is inclined with respect to the first direction and the extension direction of the shroud 31.

[0017] The first shroud 31 is configured in a disk shape. The first shroud 31 extends along a plane intersecting with the first direction. The first shroud 31 is flat and extends, for example, along a direction perpendicular to the first direction.

[0018] An impeller hub 31a is provided at the center of the first shroud 31. The impeller hub 31a is a cylindrical member integrally provided at the center of the shroud 31, and protrudes from the first shroud 31 in one and the other axial directions. The impeller hub 31a is disposed around the rotating shaft 21 and has an outer surface whose diameter is partially enlarged in the direction of the rotating shaft 21. For example, in this embodiment, at least a part of the impeller hub 31a is configured in a truncated cone shape whose outer diameter gradually enlarges toward the first shroud 31 side. An insertion hole 31b having a two-face width for positioning is formed at the center of the impeller hub 31a. The rotating shaft 21 is fixed to this insertion hole 31b. The outer diameter of the impeller hub 31a enlarges toward the first shroud 31 side. The impeller hub 31a may be configured integrally with the first shroud 31 or may be configured as a separate body. For example, an opening may be formed in the center of the first shroud 31, and a cylindrical impeller hub 31a may be provided in the opening.

[0019] The second shroud 32 is disposed opposite one side of the first shroud 31 in the first direction. The second shroud 32 has a circular outer shape in a plan view in the axial direction. The second shroud 32 has a circular suction mouth 32a that sucks in a fluid. An outer peripheral edge portion of the suction mouth 32a of the shroud 32 is rotatably supported inside the pump casing 22 via a liner ring.

[0020] The second shroud 32 is formed in a cylindrical shape in which the outer peripheral portion extends along a plane direction perpendicular to the first direction and the suction mouth 32a at the center portion extends along the first direction in a cross-sectional view along the first direction. The surface of the second shroud 32 on the other side in the first direction is welded and joined to the end face 33e of the blade 33.

[0021] The blade 33 is disposed on one surface of the first shroud 31 in the first direction, and extends in a direction intersecting the direction of the rotation shaft 21. One or more blades 33 are provided between the pair of shrouds 31, 32. One end of the blade 33 is disposed on the center side of the shrouds 31, 32, and the other end is disposed on the outer circumferential edge of the shrouds 31, 32.

[0022] The blade 33 is erected between one main surface of the first shroud 31 and the other main surface of the second shroud 32. The blade 33 is formed in a shape, for example, a spiral shape or an involute shape, in which the diameter from the center of the shrouds 31 and 32, i.e., the rotation center of the impeller 30, varies at each position in a plan view seen in the axial direction. Moreover, the blade 33 is formed in a three-dimensional shape having a portion inclined or curved with respect to the rotation shaft 21 in a cross-sectional view along the direction of the rotation shaft 21. The inclination angle of the blade piece 33a of the blade 33 with respect to the first direction increases toward the rotation center. The blade 33 guides the water sucked from the suction mouth 32a of the second shroud 32 by the rotation of the impeller 30 to the impeller discharge port 30b on the outer periphery side.

[0023] At least a portion of the inner circumference of the blade 33 includes a blade piece 33a formed in a plate shape whose extension direction or its tangent direction is inclined relative to a second direction, which is the shroud direction that extends radially perpendicular to the first direction and the rotation axis, a joint end piece 33b arranged on the first shroud 31 side, and a joint end piece 33c arranged on the second shroud 32 side, which are integrally connected to each other.

[0024] That is, the inner peripheral portion of the blade 33 is configured such that, in a cross-sectional view perpendicular to the extending direction of the blade 33 and along the first direction, the joint end pieces 33b, 33c have a smaller angle with respect to the first direction than the blade piece 33a. That is, the blade 33 includes the joint end pieces 33b, 33c which extend in a standing direction from one side surface of the shrouds 31, 32 and are joined to the shrouds 31, 32, and the blade piece 33a which is inclined or curved with respect to the joint end pieces 33b, 33c.

[0025] The blade piece 33a extends along the first direction at its outer circumferential end, and is twisted so that the inclination angle with respect to the first direction increases as it approaches the rotation shaft 21. Joint end pieces 33b, 33c are disposed continuously to both ends of the blade piece 33a, respectively.

[0026] A pair of joint end pieces 33b, 33c have end faces along the surfaces of the facing shrouds 31, 32. That is, the first joint end piece 33b and the second joint end piece 33c have joint end faces 33d, 33e along the surfaces of the facing first shroud 31 or second shroud 32. For example, the first joint end piece 33b and the second joint end piece 33c are configured to have a surface shape that can be easily welded to the facing shrouds 31, 32. For example, the thickness of the blade 33 and the angle between the shrouds 31, 32 and the joint end faces 33d, 33e are set so that the interval between the joint end faces 33d, 33e and the shrouds 31, 32 is within a predetermined value. Preferably, the maximum value of the gap formed between the surfaces of the shrouds 31, 32 and the joint end faces 33d, 33e is configured to be a predetermined interval, for example, 0.5 mm or less.

[0027] An end face 33d of a joint end piece 33b on one side of the blade 33 extends along a plane perpendicular to the first direction, has a surface conforming to the surface of the first shroud 31, and is welded to the first shroud 31. An end face 33e of a joint end piece 33c on the other side of the blade 33 has a surface conforming to the surface of the outer circumferential portion of the second shroud 32, i.e., extends along a plane perpendicular to the first direction, and is welded to the second shroud 32.

[0028] As an example in the present embodiment, the first joint end piece 33b and the second joint end piece 33c extend along an axial direction that is a direction perpendicular to the direction in which the first shroud 31 and the second shroud 32 extend.

[0029] The outer shape of the blade 33 is surrounded by an end face 33d joined to the first shroud 31, an end face 33e joined to the second shroud 32, an outer end face 33f connecting the end faces 33d, 33e on the outer circumferential edge side, an inner end face 33g extending from the end face 33e toward the first shroud on the outer circumferential edge side, and a relief face 33h connecting an end of the inner end face 33g on the first shroud 31 side and an inner end of the end face 33d. That is, the blade 33 has a shape in which a corner part on the first shroud 31 side is cut out. The blade 33 has a relief part 33i at an end part on the rotating shaft 21 side, which is one end side in the extension direction, where a part of the first shroud 31 on one axial side of the end face on the rotating shaft 21 side is retracted in a direction away from the rotating shaft 21 in the extension direction. That is, the end face of the blade 33 on the rotating shaft 21 side has an inner end face 33g, and a part of the inner end face 33g from the end of the inner end face 33g on the first shroud 31 side to the first shroud 31 has a flank face 33h that is inclined or curved in a direction away from the rotating shaft 21. The inner end face 33g is disposed in an inner region of the suction mouth 32a of the second shroud 32. That is, when the impeller 30 is viewed in the axial direction from the suction side, the inner end face 33g is disposed in a position where the inner end face 33g is visible within the suction mouth 32a of the shroud 32, and the outermost end of the inner end face 33g is disposed along the opening of the suction mouth 32a. As shown in FIG. 10, the inner end face 33g is designed, for example, from a design starting point at a position closer to the rotating shaft 21 than the intersection point of the impeller hub 31a with the first shroud 31, and is set along a slope from the design starting point to the mouth portion, i.e., the suction mouth 32a. In other words, a portion that is a certain distance away from the design starting point in the radial and axial directions becomes an end portion of the inner end surface 33g.

[0030] That is, for example, an impeller 230 formed by lost wax casting is shown in Fig. 12 as a comparative example. In the impeller 230 according to the comparative example, the design starting point is a position P0 on a circle having a diameter φD0, which is obtained by projecting the outer edge of the suction part side of the impeller hub 231a onto the first shroud 231, and the end face of the blade 233 is designed along a line connecting the design starting point to a position P2 of the opening inner edge of the suction mouth 32a (mouth part) of the second shroud 32. In the impeller 30 according to the present embodiment, the end face of the blade 33 is set using the same position as the impeller 230 formed by such lost wax casting as the design starting point, and a part of the first shroud 31 side is cut out so as to be partially evacuated, thereby avoiding interference between the blade 33 and the impeller hub 31a. 11, in another embodiment, the design starting point is a point on a circle of a small diameter φD0 close to the rotation axis, rather than a point P1 on a circle of a diameter φD1 that is the outermost surface position of the impeller hub 31a, or a point P1' on a circle of a diameter φD1' that secures a small gap outside P1 as the design starting point for the end face of the blade 33. In other words, the intersection point between a virtual line extending the inner end face 33g and the main surface of the first shroud 31 is located closer to the rotation axis than the inner end face 33g and the flank 33h of the blade 33. Furthermore, in this embodiment, the intersection point between a virtual line extending the inner end face 33g and the main surface of the first shroud 31 is located closer to the rotation axis than the intersection point between the outer surface of the impeller hub 31a that expands toward the first shroud 31 side and the first shroud 31.

[0031] For example, in this embodiment, the outer end faces 33f of the blade pieces 33a on the outer periphery side extend along the first direction, and are twisted so that the inclination angle with respect to the first direction increases as the blade pieces 33a approach the rotation shaft 21.

[0032] The clearance surface 33h is disposed at a position facing the expanding outer surface of the impeller hub 31a and is formed in a circular shape along the outer circumferential edge of the impeller hub 31a at a constant predetermined interval from the impeller hub 31a when viewed in the axial direction.

[0033] In this embodiment, an inner end face 33g is formed by the second joint piece 33c and an end face of a portion of the blade piece 33a on the second shroud 32 side up to the midpoint of the blade piece 33a. A clearance face 33h is formed by a portion from the midpoint of the blade piece 33a to the end of the blade piece 33a on the first shroud 31 side and the inner end face of the first joint piece 33b.

[0034] In the direction of the rotary shaft 21, the dimension of the clearance surface 33h is set to be equal to or greater than ⅓ and equal to or less than ½ of the entire length of the end surface of the blade 33 on the rotary shaft 21 side.

[0035] The impeller 30 is formed by joining a first shroud 31, a second shroud 32, and a blade 33, which are formed separately by, for example, pressing a steel plate, by welding. The manufacturing method of the impeller according to this embodiment includes a process of forming the first shroud 31, the second shroud 32, and the blade 33, respectively, and a process of joining and assembling the first shroud 31, the second shroud 32, and the blade 33 formed by pressing by laser welding. The impeller hub 31a is molded separately from the first shroud 31, and is joined to an opening formed in the first shroud 31 prior to a process of joining the shroud 31 and the blade 33. The blade 33 is formed into a predetermined shape by pressing a steel plate, in which one end in a first direction intersecting with the edge forming direction has a relief portion 33i retracted in the extension direction at an end face on one end side in the extension direction.

[0036] In the assembly process, first, the blades 33 are welded to the second shroud 32, and then the first shroud 31 provided with the impeller hub 31a and the second shroud 32 are arranged opposite each other with the blades 33 in between, and joined by laser welding to complete the impeller 30. At this time, one end face 33d of the blades 33 protruding from one side of the second shroud 32 faces and abuts against the surface of the first shroud 31 previously provided with the impeller hub 31a, and is joined by welding.

[0037] In the pump device 1, the impellers 30 are rotated by the rotation of the motor 11, and each impeller 30 sucks in a fluid from the suction mouth 32a, guides the fluid along a flow path formed between the blades 33 and the first and second shrouds 31 and 32, and discharges the fluid from an impeller discharge port 30b formed on the outer periphery of the impeller 30. The impeller 30 on the most primary side sucks in a fluid from the suction mouth 32a through the pump suction port. The fluid flowing out from the impeller discharge port 30b is guided by the pump casing 22 to the suction mouth 32a of the impeller 30 arranged on the secondary side. The fluid discharged from the impeller discharge port 30b of the impeller 30 arranged on the most secondary side is discharged from the pump discharge port.

[0038] According to the impeller 30 and the pump device 1 of this embodiment, the end of the blade 33 on the rotating shaft 21 side has a relief portion 33i where a part of the shroud side is retreated in a direction away from the rotating shaft 21, so that the flow passage area can be secured in a small size. That is, by forming a relief surface 33h by cutting out a part of the inner end face of the blade 33, it is possible to arrange the inner end face 33g in a position similar to that of the impeller 230 formed by lost wax casting as illustrated in FIG. 12. Therefore, the inlet area, that is, the diameter φD0 of the inner end of the part where the second joint end face 33d of the blade 33 is joined to the first shroud 31, can be reduced. That is, for example, when the shroud and the blades are manufactured by casting, the front and back shrouds and the blades are manufactured by bonding wax molds together, so that the inlet diameter φD0 of the blades can be made small to ensure the flow area. However, in a pressed impeller in which the shroud and the blades manufactured by pressing are welded together separately, it is necessary to design the blades with a diameter larger than the maximum diameter of the impeller hub so that the impeller hub and the blades do not interfere with each other. For this reason, the inlet of the blade depends on the shape of the impeller hub, and it was difficult to ensure the flow area. However, according to the above embodiment, by cutting out only a part of the end face of the blade 33 on the rotating shaft 21 side on the first shroud 31 side facing the impeller hub 31a to form the relief portion 33i, it is possible to ensure the flow area while maintaining the shape of the blade without significantly changing the design points of the blade 33. Therefore, it is not necessary to increase the shaft length W0 or the side plate length W1, and it is possible to reduce the size. Furthermore, by providing the relief portion 33i in the impeller 30, even if the outer surface of the impeller hub 31a on the first shroud 31 side is shaped to have an expanded diameter, the end face of the blade 33 can be designed along the end face leading to the opening inner edge of the suction mouth 32a of the second shroud 32 while maintaining the design point. Therefore, there is no need to reduce the diameter of the impeller hub 31a to match the position of the blade 33, and strength can be maintained. In addition, there is no need to increase the width W2 of the impeller discharge port 30b on the outer periphery, so manufacturing is easy and stress concentration can be suppressed. In addition, there is no need to significantly change the process because the number of blades can be maintained.

[0039] Furthermore, in the impeller 30, at least a portion of the blade 33 has a blade piece 33a that, when viewed in cross section, is inclined or curved with respect to a first direction and the extension direction or tangent direction of the shroud 31, and a joining end piece 33b that extends in a direction such that the inclination angle with respect to the direction perpendicular to the shroud 31 is smaller than that of the blade piece 33a and is joined to the shroud 31, making it easier to secure the welding area and facilitate manufacturing.

[0040] The present invention is not limited to the above embodiment. In the above embodiment, the pair of shrouds are flat plates extending in a direction perpendicular to the main shaft, and the pair of joint end pieces are joined to the pair of shrouds. However, the present invention is not limited to this. For example, as another embodiment, the joint end pieces 33b and 33c may not be provided. Even in this case, by retracting a part of the inner end face on the first shroud side, it is possible to prevent interference and ensure the flow passage area while maintaining the shape of the blade without significantly changing the design point of the blade 33.

[0041] In addition, in the above embodiment, an example has been described in which the impeller hub 31a is configured as a separate body from the first shroud 31, but the present invention is not limited to this, and the impeller hub 31a may be configured to be molded integrally with the first shroud 31. For example, the impeller hub 31a may be provided integrally with the first shroud 31 when the first shroud 31 is molded.

[0042] In the above embodiment, the impeller 30 is a closed type having the second shroud 32, but the present invention is not limited to this and may be, for example, an open type impeller.

[0043] In the above embodiment, the impeller 30 is formed by pressing a steel plate to form the first shroud 31, the second shroud 32, and the blades 33, and then laser welding the first shroud 31, the second shroud 32, and the blades 33. However, the present invention is not limited to this, and the impeller may be made of resin. For example, the first shroud 31, the second shroud 32, and the blades 33 may be formed by resin molding, and the first shroud 31, the second shroud 32, and the blades 33 may be joined and assembled by ultrasonic welding or vibration welding to form the impeller.

[0044] Alternatively, the impeller may be made of resin and formed by inserting an impeller hub, instead of pressing. That is, in a configuration in which the main shaft insertion part and the blades are separate, by cutting out and retracting a part of the end face of the blade, it is possible to avoid interference with the impeller hub while maintaining a small size. Note that, although the relief portion is formed on the blade side in the above embodiment, for example, a relief portion may be formed on the impeller hub side by cutting out a predetermined portion on the outer surface of the impeller hub where the blades are formed so as to be recessed toward the shaft center.

[0045] In addition, although a multi-stage pump device has been exemplified in the above embodiment, the number of impellers is not limited to the above. For example, a single stage is also possible. Furthermore, the number of blades provided on the impeller may be any number. Furthermore, although a turbine pump has been exemplified, the present invention is not limited to this and can be applied to various pump devices.

[0046] The present invention is not limited to the above-mentioned embodiment, and can be modified in various ways without departing from the gist of the present invention. The embodiments may be combined as appropriate, 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. The following is a description equivalent to the invention described in the claims of the original application. [1] A shroud extending in a direction intersecting with the rotation axis direction; an impeller comprising: a blade arranged on one side surface of the shroud in the rotational axis direction, extending in a direction intersecting the rotational axis direction, and having a recessed portion at an end portion on the rotational axis side where the shroud side is partially recessed in a direction away from the rotational axis. [2] The impeller described in [1], wherein the end face of the blade facing the rotating shaft has an inner end face along the rotating shaft, and a relief surface that is inclined or curved in a direction away from the rotating shaft from the shroud side end of the inner end face to the shroud. [3] The impeller according to [1] or [2], wherein the dimension of the relief surface in the direction of the rotation axis is greater than or equal to 1 / 3 and less than or equal to 1 / 2 of the overall length of the end face of the blade on the rotation axis side. [4] An impeller described in any of [1] to [3], wherein at least a portion of the blades are provided with blade pieces that, when viewed in cross section, are inclined or curved with respect to the rotation axis direction and the extension direction or tangent direction of the shroud, and joining end pieces that extend in a direction such that their angle with respect to the direction perpendicular to the shroud is smaller than that of the blade pieces and are joined to the shroud. [5] The impeller described in any one of [2] to [4], wherein the shroud has a cylindrical impeller hub arranged around the rotating shaft. [6] The impeller hub has an outer surface whose diameter increases in a portion in the rotation axis direction, The impeller described in [5], wherein the relief surface is disposed in a position opposite the expanding outer surface of the impeller hub. [7] An impeller as described in any of [1] to [6], comprising a pair of shrouds arranged opposite each other with the blade in between in the direction of the rotation axis, wherein at least one of the blades on the shroud side has a recessed portion in a direction away from the rotation axis. [8] The impeller described in any one of [1] to [7], wherein the shroud and the blades are formed by press-molding a steel plate. [9] The impeller described in any one of [1] to [7], wherein the shroud and the blades are formed by resin molding.

[10] [1] to [9], and an impeller according to any one of the above. A rotating shaft fixed to the impeller; and a pump casing that houses the impeller.

[11] forming a shroud; A step of pressing a metal plate to form a blade, in which one end of an end face of an end portion on one end side of an extension direction in a first direction intersecting the extension direction is retracted in the extension direction; disposing an end surface of one end of the blade in a first direction opposite to the shroud, and welding the end surface of the one end of the blade in the first direction to a surface of the shroud; A method for manufacturing an impeller comprising: [Explanation of symbols]

[0047] 1...pump device, 11...motor, 12...pump section, 21...rotating shaft, 22...pump casing, 23...casing cover, 30...impeller, 31...first shroud, 31a...impeller hub, 31b...insertion hole, 32...second shroud, 32a...suction mouth, 33...blade, 33a...blade piece, 33b...joint end piece, 33c...joint end piece, 33d...joint end surface, 33e...joint end surface, 33f...outer end surface, 33g...inner end surface, 33h...relief surface, 33i...relief portion.

Claims

1. A shroud extending in a direction intersecting with the rotation axis direction; an impeller including: a blade disposed on one surface of the shroud in the rotation axis direction, extending in a direction intersecting the rotation axis direction, and having a relief portion at an end portion on the rotation axis side where the shroud side is partially retracted in a direction away from the rotation axis; A rotating shaft fixed to the impeller; A pump casing that houses the impeller. The shroud includes a cylindrical impeller hub disposed around the rotating shaft, the end surface of the blade on the side of the rotation shaft has an inner end surface, and a relief surface inclined or curved in a direction away from the rotation shaft at a portion extending from an end portion of the inner end surface on the side of the shroud to the shroud, At least a portion of the blades has blade pieces that are inclined or curved with respect to the rotation axis direction and the extension direction or tangential direction of the shroud in a cross-sectional view, The relief surface is disposed at a position facing an outer surface of the impeller hub, The blade is configured to have a three-dimensional shape having a portion that is inclined or curved with respect to the rotation axis in a cross-sectional view taken along the rotation axis direction, The relief surface is formed by a portion from a midpoint of the blade piece to an end portion on the first shroud side and an inner end surface of the joining end piece.

2. A pump apparatus as described in claim 1, wherein the joining end piece is extended in a direction such that its angle with respect to a direction perpendicular to the shroud is smaller than that of the blade piece and joined to the shroud.

3. 3. The pump apparatus according to claim 1, further comprising: another shroud disposed opposite the shroud with the blades interposed therebetween in the direction of the rotation axis.

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