Impeller, method for manufacturing impeller, and magnetically-levitated pump

Abstract

An impeller of the present disclosure comprises: a resin body part having a disk-shaped base plate, and a plurality of vanes provided on the base plate at intervals in the circumferential direction and protruding to one side in the axial direction, each vane being formed with a thinned portion recessed from one surface on the one side in the axial direction of the vane to the other side in the axial direction; an embedded part embedded inside the thinned portion; and a resin top plate part provided on the one surface of the plurality of vanes. The plurality of vanes are integrally molded with the top plate part.

Description

Impeller, method for producing impeller, and magnetic levitation pump

[0001] The present disclosure relates to an impeller, a method for producing an impeller, and a magnetic levitation pump. This application claims priority based on Japanese Patent Application No. 2025-052966 filed on March 27, 2025, and incorporates all the content described in the said Japanese application by reference.

[0002] Generally, a magnetic levitation pump includes a housing, an impeller disposed in the housing, a rotating body that rotates together with the impeller, a magnetic bearing that supports the rotating body in a non-contact manner, and a motor that rotationally drives the rotating body (see, for example, Patent Document 1). FIG. 10 is a perspective view showing a conventional impeller 90 of a magnetic levitation pump. As shown in FIG. 10, the impeller 90 is made of resin, and includes a main body portion 91 and a top plate portion 92.

[0003] The main body portion 91 includes a disk-shaped base plate 93 and a plurality of blades 94 provided at intervals in the circumferential direction on the base plate 93. Each blade 94 is formed to be thicker in the vertical direction than the base plate 93. For this reason, each blade 94 is formed with a recessed thinning portion 95 that is recessed downward from the upper surface thereof. The top plate portion 92 is provided on the upper surface of each blade 94 of the main body portion 91. When manufacturing the impeller 90, after molding the main body portion 91 and the top plate portion 92 respectively by molds, the top plate portion 92 is welded to the upper surface of each blade 94 of the main body portion 91.

[0004] Japanese Unexamined Patent Publication No. 2020-128745

[0005] For the above-mentioned impeller 90, the step of welding the top plate portion 92 to the main body portion 91 and the step of removing the portion protruding outward in the radial direction during welding by cutting are required, so the productivity of the impeller 90 is low. Therefore, it is conceivable to integrally mold the main body portion 91 and the top plate portion 92. However, in that case, the thinning portion 95 of the blade 94 becomes a closed space, so the thinning portion 95 cannot be molded by a mold. If the main body portion 91 has blades 94 without the thinning portion 95, it can be molded integrally with the top plate portion 92, but sink marks (dents) are likely to occur on the blades 94.

[0006] This disclosure is made in view of these circumstances and aims to improve the productivity of impellers while suppressing the occurrence of sink marks on the blades.

[0007] (1) The impeller of the present disclosure has a disc-shaped base plate and a plurality of blades provided on the base plate at intervals in the circumferential direction and protruding to one side in the axial direction, and each blade has a resin body portion formed thereon that is recessed from one surface on the axial side of the blade toward the other side in the axial direction, an embedded portion embedded inside the material removal portion, and a resin top plate portion provided on one surface of the plurality of blades, and the plurality of blades are integrally molded with the top plate portion.

[0008] According to the impeller of this disclosure, since material-removing portions are formed on the blades of the main body, sink marks on the blades can be suppressed. Furthermore, since embedded portions are embedded inside the material-removing portions of the blades, the material-removing portions do not become enclosed spaces. As a result, the blades of the main body can be molded integrally with the top plate portion using a mold. Therefore, the process of welding the top plate portion to the main body portion and the process of removing the excess portion that protrudes during welding by cutting, as in the conventional method, are eliminated, and the productivity of the impeller can be improved.

[0009] (2) In the impeller described in (1), it is preferable that the embedded portion is made of a different material from at least one of the main body portion and the top plate portion. In this case, by using an embedded portion made of a material that is cheaper than at least one of the main body portion and the top plate portion, the impeller can be manufactured at a low cost.

[0010] (3) The method for manufacturing an impeller according to the present disclosure is a method for manufacturing an impeller according to (1) or (2) above, comprising in this order: a first step of manufacturing the embedded portion; a second step of obtaining an intermediate molded body in which the embedded portion and the top plate portion are integrated by insert molding the top plate portion with the embedded portion as a first insert part using a first mold; and a third step of obtaining an impeller in which the material-removing portion with the embedded portion embedded inside is formed on the blades and the top plate portion and the blades are integrated by insert molding the main body portion with the intermediate molded body as a second insert part using a second mold.

[0011] According to the impeller manufacturing method of this disclosure, in the third step, a material-removing portion is formed on the blades of the main body. This suppresses the occurrence of sink marks on the blades. Furthermore, since an embedded portion is embedded inside the material-removing portion of the blade, the material-removing portion does not become a closed space. As a result, by using a second mold, the main body can be insert-molded so that the blades of the main body and the top plate portion are integrated. Therefore, the process of welding the top plate portion to the main body portion and the process of removing the excess portion that protrudes during welding by cutting, as in the conventional method, is eliminated, and the productivity of the impeller can be improved.

[0012] (4) In the method for manufacturing the impeller according to (3), the first mold has a mold portion having a cavity surface formed for insert molding the top plate portion, and an insertion groove into which the embedded portion is inserted as the first insert part is formed opening to the cavity surface, and the embedded portion is preferably provided with a flange portion that contacts the cavity surface of the mold portion when the embedded portion is inserted into the insertion groove of the mold portion in the second step.

[0013] In this case, during the second step, with the embedded part inserted into the insertion groove of the mold, the flange of the embedded part contacts the cavity surface of the mold. This prevents molten resin from entering the insertion groove during insert molding of the top plate. As a result, it is possible to prevent the embedded part from lifting due to molten resin that has entered the insertion groove.

[0014] (5) The magnetic levitation pump of the present disclosure comprises a housing having an inlet and an outlet for the fluid to be transferred, an impeller as described in (1) or (2) disposed within the housing, a rotating body that rotates together with the impeller, a motor that rotates the rotating body, and a magnetic bearing that supports the rotating body in a non-contact manner. The magnetic levitation pump of the present disclosure provides the same effects as the impeller described above.

[0015] According to this disclosure, it is possible to improve the productivity of the impeller while suppressing the occurrence of sink marks on the blades.

[0016] This is a schematic cross-sectional view showing a magnetic levitation pump according to an embodiment of the present disclosure. This is a perspective view showing the impeller of the magnetic levitation pump. This is a cross-sectional view showing the impeller. This is a perspective view showing the main body of the impeller. This is a cross-sectional view showing the embedded part manufactured in the first step. This is an explanatory diagram showing the second step. This is an explanatory diagram showing the third step. This is a plan view of the fixed mold part and the sliding part of the second mold, viewed from the axial upper side. This shows a modified example of the embedded part and corresponds to the upper part of Figure 6. This is a perspective view showing the impeller of a conventional magnetic levitation pump.

[0017] Next, preferred embodiments will be described with reference to the attached drawings. [Overall Configuration] Figure 1 is a schematic cross-sectional view showing a magnetic levitation pump 1 according to an embodiment of the present disclosure. In Figure 1, the magnetic levitation pump 1 of this embodiment (hereinafter also simply referred to as "pump 1") consists of a centrifugal pump. Pump 1 comprises a housing 2, a rotating body 3, a motor 4, a pair of magnetic bearings 5, and an impeller 6.

[0018] Hereinafter, in this disclosure, the direction along the axis C of the pump 1 is the axial direction of the pump 1 and is simply referred to as the "axial direction." The upper side of Figure 1 (one side in the axial direction) is referred to as the "upper axial side," and the lower side of Figure 1 (the other side in the axial direction) is referred to as the "lower axial side." The direction perpendicular to the axis C is the radial direction of the pump 1 and is simply referred to as the "radial direction." The direction of rotation about the axis C is the circumferential direction of the pump 1 and is simply referred to as the "circumferential direction."

[0019] The housing 2 comprises a housing body 21, a first wall 25 provided on the axial upper side of the housing body 21, and a second wall 26 provided on the axial lower side of the housing body 21. The housing body 21 has an outer cylindrical wall 22, an inner cylindrical wall 23 disposed within the outer cylindrical wall 22, and a partition wall 24 integrally provided at the axial upper end of the inner cylindrical wall 23.

[0020] The outer cylindrical wall 22 and inner cylindrical wall 23 of the housing body 21 are each formed in a cylindrical shape with respect to axis C. The outer diameter of the inner cylindrical wall 23 is smaller than the inner diameter of the outer cylindrical wall 22. The partition wall 24 is formed in an annular shape. The inner circumferential end of the partition wall 24 is connected to the axially upper end of the inner cylindrical wall 23. The outer diameter of the partition wall 24 is approximately the same as the outer diameter of the outer cylindrical wall 22. The axially lower side surface of the outer circumference of the partition wall 24 is fixed in contact with the axially upper end surface of the outer cylindrical wall 22.

[0021] The second wall 26 is formed in a disc shape with axis C as its center. The outer diameter of the second wall 26 is approximately the same as the outer diameter of the outer cylinder wall 22. The axially lower end of the outer cylinder wall 22 and the axially lower end of the inner cylinder wall 23 abut and are fixed to the axially upper end face of the second wall 26. Within the housing 2, a stator 27 made of a cylindrical magnetic material is provided in the region partitioned by the outer cylinder wall 22, partition wall 24, inner cylinder wall 23, and second wall 26. The inner circumferential surface of the stator 27 is in contact with the outer circumferential surface of the inner cylinder wall 23. The material of the stator 27 may be a material other than a magnetic material.

[0022] The first wall 25 is formed in a disc shape with axis C as its center. The outer diameter of the first wall 25 is approximately the same as the outer diameter of the outer cylinder wall 22. The first wall 25 has a circular groove 25a that opens downward in the axial direction. Inside the housing 2, there is a housing space 28 that is partitioned by the groove 25a of the first wall 25 and the partition wall 24. The housing space 28 is in communication with the internal space of the inner cylinder wall 23 of the housing body 21.

[0023] A suction port 2a for drawing in the transfer fluid is formed in the central part of the upper axial side of the first wall 25. The suction port 2a is formed to penetrate from the upper axial end face of the first wall 25 to the bottom surface of the groove 25a. A discharge port 2b for discharging the transfer fluid is formed at a predetermined location in the circumferential direction of the first wall 25. The discharge port 2b is formed to penetrate from the outer circumferential surface of the first wall 25 to the inner circumferential surface of the groove 25a.

[0024] The rotating body 3 is arranged within the housing 2 so as to be rotatable about axis C. Most of the rotating body 3 is located in the internal space of the inner cylinder wall 23. The remaining portion of the rotating body 3, the axially upper end, is located in the housing space 28. The rotating body 3 has a cylindrical portion 31, a lid portion 32 that closes the axially upper opening of the cylindrical portion 31, and a tubular portion 33 located inside the cylindrical portion 31.

[0025] The cylindrical portion 31 is formed in the shape of a bottomed cylinder. The cylindrical portion 31 has a cylindrical body 311 and a bottom plate 312 provided on the axially lower side of the cylindrical body 311. The outer diameter of the cylindrical body 311 is smaller than the inner diameter of the inner cylindrical wall 23 of the housing body 21. A cylindrical flow path 7 through which the transferred fluid flows is formed between the cylindrical body 311 and the inner cylindrical wall 23. The bottom plate 312 is formed in the shape of an annular ring and closes the axially lower opening of the cylindrical body 311. A flow path 8 through which the transferred fluid flows is formed between the bottom plate 312 of the cylindrical portion 31 and the second wall 26 of the housing 2.

[0026] The lid portion 32 is formed in a disc shape and is fitted onto the axially upper end of the cylindrical portion 31. The lid portion 32 has a screw hole 321 that opens axially upward. The male screw portion 62 (described later) of the impeller 6 is screwed into the screw hole 321 of the lid portion 32 from the axially upper side. The lid portion 32 also has an insertion hole 322 that opens axially downward.

[0027] The pipe section 33 is a pipe through which the transferred fluid flows and is formed in a cylindrical shape. The axial upper end of the pipe section 33 is inserted into and fixed in the insertion hole 322 of the lid section 32. The axial lower end of the pipe section 33 is inserted into and fixed in the inner circumference of the bottom plate 312 of the cylindrical section 31. The axial lower opening of the pipe section 33 is in communication with the flow path 8.

[0028] Within the rotating body 3, a rotor 34 made of a cylindrical magnetic material is provided in the region partitioned by the cylindrical body 311, the bottom plate 312, the tubular section 33, and the lid section 32. The outer circumferential surface of the rotor 34 is in contact with the inner circumferential surface of the cylindrical body 311. The material of the rotor 34 may be a material other than a magnetic material.

[0029] The impeller 6 is located in the housing space 28 within the housing 2 and is mounted on the lid 32 of the rotating body 3. The impeller 6 is rotatable together with the rotating body 3 around axis C. When the impeller 6 rotates, the fluid being transferred flows into the impeller 6 from the suction port 2a of the housing 2, and due to the centrifugal force accompanying the rotation of the impeller 6, it flows out of the impeller 6 into the housing space 28 of the housing 2 and is discharged outside the housing 2 from the discharge port 2b of the housing 2. Details of the impeller 6 will be described later.

[0030] A portion of the transfer fluid that flows out from the impeller 6 into the housing space 28 of the housing 2 is not discharged from the discharge port 2b, but passes through the flow paths 7 and 8 between the housing 2 and the rotating body 3, and flows into the pipe section 33 from the axial lower side of the rotating body 3. The transfer fluid that has flowed into the pipe section 33 flows back into the impeller 6 from the axial upper opening of the pipe section 33. This circulation of a portion of the transfer fluid can suppress axial movement of the non-contact supported rotating body 3 and impeller 6.

[0031] Motor 4 rotates the rotating body 3. Motor 4 has a stator 41 provided in the housing 2 and a rotor 42 provided in the rotating body 3. The stator 41 is provided on the inner circumference side of the stator 27 inside the housing 2 and is in contact with the outer circumference surface of the inner cylinder wall 23. The rotor 42 is provided on the outer circumference side of the rotor 34 inside the rotating body 3, at a position radially opposite to the stator 41. The rotor 42 is in contact with the inner circumference surface of the cylindrical body 311 of the rotating body 3. When current is applied to the stator 41, a rotating magnetic field is generated, causing the rotor 42 to rotate together with the rotating body 3.

[0032] A pair of magnetic bearings 5 ​​support the rotating body 3 without contact with the housing 2. Each magnetic bearing 5 has a fixed magnetic portion 51 provided on the housing 2 and a rotating magnetic portion 52 provided on the rotating body 3.

[0033] The fixed magnetic part 51 is provided on the inner circumference side of the stator 27 within the housing 2 and is in contact with the outer circumferential surface of the inner cylinder wall 23. The rotating magnetic part 52 is provided on the outer circumference side of the rotor 34 within the rotating body 3, at a position radially opposite to the fixed magnetic part 51. The rotating magnetic part 52 is in contact with the inner circumferential surface of the cylindrical body 311 of the rotating body 3. Both the fixed magnetic part 51 and the rotating magnetic part 52 are formed in an annular shape using a permanent magnet or a magnetic material such as iron. Magnetic repulsion force is generated between the fixed magnetic part 51 and the rotating magnetic part 52 of each magnetic bearing 5, so that the rotating body 3 is supported without contact with the housing 2.

[0034] [Impeller Structure] Figure 2 is a perspective view showing the impeller 6. Figure 3 is a cross-sectional view showing the impeller 6. In Figures 2 and 3, the impeller 6 comprises a main body portion 60, a top plate portion 65, and a plurality of embedded portions 66. The main body portion 60 is made of resin. Specifically, since the main body portion 60 comes into contact with the transferred fluid, it is made of a resin material that is appropriate to the characteristics of the transferred fluid. In this embodiment, the main body portion 60 is made of, for example, tetrafluoroethylene perfluoroalkyl vinyl ether copolymer (PFA), which is a fluororesin.

[0035] Figure 4 is a perspective view showing the main body 60 of the impeller 6. In Figures 1 to 4, the main body 60 has a base plate 61, a male threaded portion 62, and a plurality of blades 63. The base plate 61 is formed in the shape of a disc. The base plate 61 has a larger diameter than the rotating body 3. The male threaded portion 62 is formed in the shape of a cylinder. The male threaded portion 62 is integrally provided concentrically with the base plate 61 on the outer surface 61a on the axial lower side of the base plate 61. The male threaded portion 62 protrudes axially downward from the outer surface 61a of the base plate 61. As described above, the male threaded portion 62 is screwed into the screw hole 321 of the lid portion 32 of the rotating body 3. A flow path hole 64 for the transfer fluid is formed to penetrate axially through the central part of the base plate 61 and the male threaded portion 62. The flow path hole 64 communicates with the axial upper opening of the pipe portion 33.

[0036] Multiple blades 63 are integrally provided on the axially upper inner surface 61b of the base plate 61, spaced apart in the circumferential direction. In this embodiment, four blades 63 are integrally provided on the inner surface 61b of the base plate 61, spaced equally apart in the circumferential direction. The multiple blades 63 are integrally molded with the top plate portion 65. Details will be described later.

[0037] Each blade 63 protrudes upward in the axial direction from the inner surface 61b of the base plate 61 and is formed to be thicker in the axial direction than the base plate 61. Each blade 63 is formed to gradually spread out in a fan shape from the radially inner side to the radially outer side of the base plate 61 in a plan view, for example, when viewed from above in the axial direction. The radially outer end of each blade 63 in this embodiment protrudes radially outward from the base plate 61.

[0038] Each blade 63 has a concave material-removing portion 63b formed therein. The material-removing portion 63b is formed by recessing from the axially upper end face (one surface) 63a of the blade 63 downwards in the axial direction. In this embodiment, the material-removing portion 63b is formed by recessing down to the inner surface 61b of the base plate 61. For example, in a plan view from the axially upper side, the material-removing portion 63b is formed to gradually spread out in a fan shape from the radially inner side to the radially outer side, in accordance with the shape of the blade 63.

[0039] The top plate portion 65 is formed in an annular shape. The top plate portion 65 is made of resin. Specifically, since the top plate portion 65 is in contact with the transported fluid, it is made of a resin material that is appropriate to the characteristics of the transported fluid. In this embodiment, the top plate portion 65 is made of the same PFA as the main body portion 60. The top plate portion 65 is provided on the end faces 63a of the multiple blades 63 in the main body portion 60. As described above, since the multiple blades 63 are molded integrally with the top plate portion 65, the end faces 63a of each blade 63 are in close contact with a part of the axially lower inner surface 65a of the top plate portion 65.

[0040] Multiple recesses 65b are formed on the inner surface 65a of the top plate portion 65, specifically at positions corresponding to the material removal portions 63b of each wing 63 on the inner surface 65a of the top plate portion 65. Although not shown in the illustration, each recess 65b is formed to gradually widen in a fan shape from the radially inward to the radially outward in a plan view taken from the axially downward side, in accordance with the shape of the material removal portion 63b.

[0041] The inner circumferential hole of the top plate portion 65 serves as an inlet 65c through which the transferred fluid flows into the impeller 6. Between the base plate 61 and the top plate portion 65, a flow path 67 is formed between adjacent blades 63 in the circumferential direction, through which the transferred fluid flows from the radially inner side to the radially outer side. The radially outer opening of each flow path 67 serves as an outlet 68 through which the transferred fluid flows out of the impeller 6.

[0042] As the impeller 6 rotates around axis C, the transfer fluid drawn in from the suction port 2a of the housing 2 flows into the impeller 6 through the inlet 65c of the impeller 6. Also, as described above, the transfer fluid flowing through the pipe section 33 of the rotating body 3 passes through the flow path hole 64 of the main body 60 and flows into the impeller 6. The transfer fluid that has flowed into the impeller 6 passes through the flow paths 67 between adjacent blades 63 due to the centrifugal force accompanying the rotation of the multiple blades 63, and flows out from the outlet 68 of the impeller 6 into the housing space 28 of the housing 2. The transfer fluid that has flowed out into the housing space 28 of the housing 2 is discharged outside the housing 2 from the discharge port 2b as described above.

[0043] Multiple embedded portions 66 are provided within the main body portion 60. Since the embedded portions 66 do not come into contact with the transferred fluid, they do not need to be made of a material that matches the characteristics of the transferred fluid. For this reason, it is preferable that the embedded portions 66 are made of a different material from the main body portion 60 and the top plate portion 65. In this embodiment, for example, the embedded portions 66 are made of an epoxy resin different from the resin material (PFA) of the main body portion 60 and the top plate portion 65.

[0044] The embedded portions 66 are embedded inside the recessed portion 63b for weight reduction of each blade 63. Each embedded portion 66 of the present embodiment is embedded inside the recessed portion 63b for weight reduction of the blade 63 and inside the recessed portion 65b of the top plate portion 65 corresponding to the recessed portion 63b for weight reduction. Each embedded portion 66 is formed in the same shape as the recessed portion 63b for weight reduction and the recessed portion 65b in a plan view seen from the upper side in the axial direction (see FIG. 8). Since the recessed portion 63b for weight reduction and the recessed portion 65b are molded integrally with the embedded portion 66, the embedded portion 66 is in close contact with the inner surface of the recessed portion 63b for weight reduction and the inner surface of the recessed portion 65b. Accordingly, the same number (four in this case) of embedded portions 66 as the number of recessed portions 63b for weight reduction are provided in the main body portion 60.

[0045] [Method of manufacturing impeller] Next, a method of manufacturing the impeller 6 of the present embodiment will be described with reference to FIGS. 5 to 8. The impeller 6 is manufactured in the order of a first step, a second step, and a third step. Each step will be described in detail below. <First step> In the first step, a plurality of embedded portions 66 are respectively manufactured. FIG. 5 is a cross-sectional view showing the embedded portion 66 manufactured by the first step. Since each embedded portion 66 of the present embodiment is made of resin as described above, it is molded by a mold (not shown).

[0046] <Second step> FIG. 6 is an explanatory view showing the second step. As shown in FIG. 6, in the second step, a first mold 70 is used. The first mold 70 includes a fixed mold portion (mold portion) 71 and a movable mold portion 72.

[0047] A cavity surface 71a and a plurality of insertion grooves 71b are formed on the upper side of the fixed mold portion 71 in the axial direction. Each of the insertion grooves 71b is formed to open to the cavity surface 71a. The number of the insertion grooves 71b is the same as the number of the embedded portions 66 (four in this case). In each insertion groove 71b, the embedded portion 66 is inserted as an insert component (first insert component). Each insertion groove 71b is formed such that, in a state where the embedded portion 66 is inserted, the end portion on the upper side in the axial direction of the embedded portion 66 is exposed.

[0048] The movable mold portion 72 is axially movable relative to the fixed mold portion 71. A cavity surface 72a is formed on the axially lower side of the movable mold portion 72. As shown in the middle section of Fig. 6, when the movable mold portion 72 moves axially downward, the cavity surface 71a of the fixed mold portion 71 and the cavity surface 72a of the movable mold portion 72 form a cavity 73 in which the top plate portion 65 is insert-molded. The movable mold portion 72 is formed with a passage 72b including a sprue, a runner and the like for supplying molten resin to the cavity 73.

[0049] When the first mold 70 is used, first, as shown in the upper section of Fig. 6, the embedded portions 66 are inserted as insert components into the respective insertion grooves 71b of the fixed mold portion 71. Next, as shown in the middle section of Fig. 6, with the movable mold portion 72 moved axially downward, molten resin is supplied into the passage 72b of the movable mold portion 72, and the cavity 73 is filled with the molten resin. Thereby, the top plate portion 65 is insert-molded, and as shown in the lower section of Fig. 6, an intermediate molded body 10 in which the plurality of embedded portions 66 and the top plate portion 65 are integrated is obtained.

[0050] <Third Step> Fig. 7 is an explanatory diagram showing the third step. As shown in Fig. 7, in the third step, a second mold 80 is used. The second mold 80 includes a fixed mold portion 81, a movable mold portion 82, and a plurality of slide portions 83.

[0051] A cavity surface 81a and insertion grooves 81b are formed on the axially upper side of the fixed mold portion 81. The insertion groove 81b is an annular groove formed opening to the cavity surface 81a. The intermediate molded body 10 is inserted as an insert component (second insert component) into the insertion groove 81b. At that time, the intermediate molded body 10 is inserted into the insertion groove 81b with each embedded portion 66 oriented axially upward. The insertion groove 81b is formed such that, in a state where the intermediate molded body 10 is inserted, the axially upper end surface of the intermediate molded body 10 (the inner surface 65a of the top plate portion 65) is exposed.

[0052] Figure 8 is a plan view of the fixed mold section 81 and the sliding section 83 as seen from the axial upper side. In Figures 7 and 8, the multiple sliding sections 83 are components for forming a flow path 67 (see Figure 3) within the main body 60 of the impeller 6. The multiple sliding sections 83 are arranged at equal intervals in the circumferential direction on the axial upper side of the fixed mold section 81. Each sliding section 83 is movable radially along the inner surface 65a of the top plate section 65 while the intermediate molded body 10 is inserted into the insertion groove 81b of the fixed mold section 81. Each sliding section 83 is positioned between adjacent embedded sections 66 in the circumferential direction by moving from the radial outer side to the radial inner side along the inner surface 65a of the top plate section 65.

[0053] The movable mold section 82 is movable in the axial direction relative to the fixed mold section 81. A cavity surface 82a is formed on the axially lower side of the movable mold section 82. As shown in the lower part of Figure 7, when the movable mold section 82 moves axially downward, the cavity surface 81a of the fixed mold section 81, the cavity surface 82a of the movable mold section 82, and the multiple sliding sections 83 form a cavity 84 into which the main body section 60 is insert molded. The movable mold section 82 has passages (not shown) including sprues and runners for supplying molten resin to the cavity 84.

[0054] When the second mold 80 is used, first, as shown in the upper part of Figure 7, the intermediate molded body 10 is inserted as an insert part into the insertion groove 81b of the fixed mold part 81. Next, as shown in the middle part of Figure 7, each of the multiple slide parts 83 moves from the radially outer to the radially inner along the inner surface 65a of the top plate part 65 of the intermediate molded body 10. As a result, each slide part 83 is positioned between adjacent embedded parts 66 in the circumferential direction of the intermediate molded body 10.

[0055] Next, as shown in the lower part of Figure 7, the movable mold section 72 is moved axially downward. In this state, molten resin is supplied to the passage of the movable mold section 72, and the cavity 84 is filled with molten resin. As a result, the main body section 60, which includes the base plate 61, the male screw section 62, and the multiple blades 63, is insert molded. At this time, a material-removing section 63b is formed in each blade 63 with an embedded section 66 embedded inside, and the multiple blades 63 and the top plate section 65 are integrated to obtain the impeller 6 shown in Figure 3.

[0056] [Effects] According to this embodiment, in the third step, a material-removing portion 63b is formed on each blade 63 of the main body 60. This suppresses the occurrence of sink marks on each blade 63. Furthermore, since an embedded portion 66 is embedded inside the material-removing portion 63b of each blade 63, the material-removing portion 63b does not become a closed space. As a result, by using the second mold 80, the main body 60 can be insert-molded so that each blade 63 of the main body 60 and the top plate portion 65 are integrated. Therefore, the process of welding the top plate portion 65 to the main body 60 and the process of removing the excess portion that protrudes during welding by cutting are eliminated, as in the conventional method, thus improving the productivity of the impeller 6. Furthermore, by embedding the embedded portion 66 inside the material-removing portion 63b of each blade 63, the rigidity of the main body 60 can be increased.

[0057] Each embedded portion 66 is made of an epoxy resin different from the resin material (PFA) of the main body portion 60 and the top plate portion 65. This allows the embedded portion 66 to be made of a less expensive material than the main body portion 60 and the top plate portion 65, thus enabling the impeller 6 to be manufactured at a lower cost.

[0058] [Modified Example of Embedded Part] Figure 9 shows a modified example of the embedded part 66, and corresponds to the upper part of Figure 6. As shown in Figure 9, in this modified example, a minute flange portion 69 is provided protruding from the side surface of each embedded part 66. The flange portion 69 is provided around the entire circumference of the side surface of the embedded part 66. In this embodiment, the flange portion 69 is molded integrally with the embedded part 66 in the first step. Note that the flange portion 69 may be provided separately from the embedded part 66.

[0059] In the second step, with the embedded portion 66 inserted into the insertion groove 71b of the fixed mold portion 71, the flange portion 69 contacts the cavity surface 71a of the fixed mold portion 71, sealing the gap between the embedded portion 66 and the insertion groove 71b. This prevents molten resin from entering the insertion groove 71b through the gap during insert molding of the top plate portion 65. As a result, it is possible to prevent the embedded portion 66 from floating upward in the axial direction due to molten resin entering the insertion groove 71b.

[0060] [Other] In this embodiment, the embedded portion 66 of the impeller 6 may be molded from the same resin material (PFA) as the main body portion 60 and the top plate portion 65. Furthermore, the embedded portion 66 is not limited to being made of resin, but may be made of metal, for example.

[0061] The main body 60 and the top plate 65 may be molded from different resin materials. In that case, the embedded portion 66 may be made from a material different from at least one of the main body 60 and the top plate 65. The number of impeller blades 63, material removal portions 63b, and embedded portions 66 of the impeller 6 is not limited to this embodiment.

[0062] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the claims, not in the sense described above, and is intended to include the meaning of equivalents to the claims and all modifications within the scope.

[0063] 1 Magnetic levitation pump 2 Housing 2a Inlet 2b Outlet 3 Rotating body 4 Motor 5 Magnetic bearing 6 Impeller 10 Intermediate molded body 60 Main body 61 Base plate 63 Blades 63a End face (one side) 63b Material removal section 65 Top plate 66 Recessed section 69 Flange section 70 First mold 71 Fixed mold section (mold section) 71a Cavity surface 71b Insertion groove 80 Second mold

Claims

1. An impeller comprising a disc-shaped base plate, and a plurality of blades provided on the base plate at circumferential intervals and projecting in one axial direction, wherein each blade has a resin body portion formed thereon, which is recessed from one surface of the blade on the axial side toward the other axial side, an embedded portion embedded inside the material-removing portion, and a resin top plate portion provided on one surface of the plurality of blades, wherein the plurality of blades are integrally molded with the top plate portion.

2. The impeller according to claim 1, wherein the embedded portion is made of a material different from at least one of the main body portion and the top plate portion.

3. A method for manufacturing an impeller according to claim 1 or claim 2, comprising in this order: a first step of manufacturing the embedded portion; a second step of obtaining an intermediate molded body in which the embedded portion and the top plate portion are integrated by insert molding the top plate portion with the embedded portion as a first insert part using a first mold; and a third step of obtaining an impeller in which the material-removing portion with the embedded portion embedded inside is formed on the blade and the top plate portion and the blade are integrated by insert molding the main body portion with the intermediate molded body as a second insert part using a second mold.

4. The method for manufacturing an impeller according to claim 3, wherein the first mold has a cavity surface formed for insert molding the top plate portion, and an insertion groove into which the embedded portion is inserted as the first insert part is formed opening to the cavity surface, and the embedded portion is provided with a flange portion that contacts the cavity surface of the mold portion when the embedded portion is inserted into the insertion groove of the mold portion in the second step.

5. A magnetic levitation pump comprising: a housing having an inlet and an outlet for a fluid to be transferred; an impeller according to claim 1 or claim 2 disposed within the housing; a rotating body that rotates together with the impeller; a motor that rotates the rotating body; and a magnetic bearing that supports the rotating body in a non-contact manner.

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