Impeller of a bearingless motor pump

Abstract

In bearingless motors, the objective is to reduce the axial thrust experienced by the impeller from the fluid. [Solution] An impeller for a bearingless motor pump, comprising: a cylindrical impeller body having a first surface, a second surface opposite to the first surface, and an outer peripheral surface between the first surface and the second surface; an intake port provided on the first surface of the impeller body for drawing in fluid; one or more discharge ports provided on the outer peripheral surface of the impeller body for discharging the fluid drawn in from the intake port; and a rotor core provided on the impeller body, wherein a notch is provided on the outer peripheral surface of the impeller body along the circumferential direction of the impeller body.

Description

Technical Field

[0001] The present application relates to an impeller of a bearingless motor pump, a pump unit of a bearingless motor pump, and a bearingless motor pump.

Background Art

[0002] A magnetic bearing is a mechanical element that supports a rotating main shaft without contact, but a separate motor is required to rotate the rotating main shaft. In contrast, in a bearingless motor, by flowing an electric current through the coils of the stator, the rotor is rotated, and the rotationally symmetric magnetic field generated by the stator is made unbalanced to generate a magnetic support force for supporting the rotor. Since the rotor and stator of the bearingless motor are configured to have both magnetic support and rotation functions, it can be configured more space-saving compared to a magnetic bearing.

[0003] A bearingless motor pump using such a bearingless motor is described, for example, in the specification of Japanese Patent Application No. 2023-212932 (Patent Document 1). In the bearingless motor pump described in this document, a pump impeller (rotor) is attached to the rotor of the motor, and the position of the rotor in the plane orthogonal to the rotation axis (in-plane displacement, for example, positions in the x-axis and y-axis directions) is controlled.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In bearingless motor pumps, the force holding the rotor (impeller) position is weak in the uncontrolled direction of rotation (in other words, the rotor is susceptible to disturbances), and depending on the magnitude of the disturbance, the rotor may collide with the casing wall. There are various types of disturbances, but one example is the thrust force (thrust) caused by the fluid. The impeller is affected by the force from the fluid being sucked in and discharged by the bearingless motor pump, and it is possible that the impeller's position cannot be controlled, causing it to hit the wall and stop rotating. There are two types of thrust force caused by fluid: axial thrust (axial direction) and radial thrust (circumferential direction), but in bearingless motor pumps, it is necessary to reduce the influence of axial thrust corresponding to the uncontrolled direction.

[0006] The present invention aims to solve at least some of the problems described above. One of the objectives of the present invention is to reduce the axial thrust that the impeller receives from the fluid in a bearingless motor. [Means for solving the problem]

[0007] According to one aspect of the present invention, an impeller for a bearingless motor pump is provided, comprising: a cylindrical impeller body having a first surface, a second surface opposite to the first surface, and an outer peripheral surface between the first surface and the second surface; an intake port provided on the first surface of the impeller body for drawing in fluid; one or more discharge ports provided on the outer peripheral surface of the impeller body for discharging the fluid drawn in from the intake port; and a rotor core provided on the impeller body, wherein a notch is provided on the outer peripheral surface of the impeller body along the circumferential direction of the impeller body. [Brief explanation of the drawing]

[0008] [Figure 1] A cross-sectional view of a bearingless motor pump according to the first embodiment. [Figure 2A] A cross-sectional view of the pump unit according to the first embodiment. [Figure 2B] An upward perspective view of the impeller of a pump unit according to the first embodiment. [Figure 2C] A side view of the impeller of a pump unit according to the first embodiment. [Figure 2D] A downward perspective view of the impeller of a pump unit according to the first embodiment. [Figure 2E] An exploded perspective view of the impeller of a pump unit according to the first embodiment. [Figure 3A] A cross-sectional view of the pump unit according to the second embodiment. [Figure 3B] A downward perspective view of the impeller of a pump unit according to the second embodiment. [Figure 3C] An exploded perspective view of the impeller of a pump unit according to the second embodiment. [Figure 4A] An upward perspective view of the impeller of a pump unit according to the third embodiment. [Figure 4B] A side view of the impeller of a pump unit according to the third embodiment. [Figure 4C] A downward perspective view of the impeller of a pump unit according to the third embodiment. [Figure 5] A downward perspective view of the impeller of a pump unit according to the fourth embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. Note that the drawings are schematic in order to facilitate understanding of the features, and the dimensional ratios of each component may not be the same as those of the actual components.

[0010] (First Embodiment) Figure 1 is a cross-sectional view of a bearingless motor pump according to the first embodiment. Figure 2A is a cross-sectional view of a pump unit according to the first embodiment. Figure 2B is an overhead perspective view of the impeller of the pump unit according to the first embodiment. Figure 2C is a side view of the impeller of the pump unit according to the first embodiment. Figure 2D is a downward perspective view of the impeller of the pump unit according to the first embodiment. Figure 2E is an exploded perspective view of the impeller of the pump unit according to the first embodiment. A bearingless motor is a motor that combines the function of rotating a rotor with the function of magnetically supporting it. In other words, a bearingless motor is a motor in which the rotor is magnetically supported and rotated by a stator without separate bearings. A bearingless motor pump is a pump that uses a bearingless motor. In a bearingless motor pump, the rotor of the pump is connected to or integrated with the rotor of the motor.

[0011] The bearingless motor pump 1 (hereinafter also simply referred to as pump 1) according to this embodiment is a pump (for example, a centrifugal pump) driven by a bearingless motor, and as shown in Figure 1, comprises a pump unit 10 and a motor unit 70 as a drive unit that drives the pump unit 10.

[0012] The pump unit 10 comprises a pump casing 20 and an impeller 50 disposed within the pump casing 20. The pump casing 20 has a fluid inlet 21 for drawing in fluid, a fluid outlet 24 for discharging fluid, and an internal space 25 for housing the impeller 50. The fluid inlet 21 is located on the rotation axis A of the impeller 50 and opens upward. The fluid inlet 21 is connected to the internal space 25 via an inlet passage 22 extending in the direction of the rotation axis A. The rotation axis A is the central axis of the impeller 50 and refers to the axis on which the impeller 50 rotates when the impeller 50 is in operation, centered relative to the stator 71, and not tilted. The fluid outlet 24 opens toward the side of the pump casing 20. The fluid outlet 24 is connected to the internal space 25 via an outlet passage 23.

[0013] The internal space 25 of the pump casing 20 includes a first internal space 26 and a second internal space 27 that is provided continuously to the first internal space 26 and fluidly communicates with the first internal space 26. The second internal space 27 has a radial dimension smaller than the radial dimension of the first internal space 26. The second internal space 27 is provided in a protruding portion 41 that protrudes downward more than other portions of the pump casing 20. The protruding portion 41 of the pump casing 20 has a radial dimension smaller than other portions of the pump casing 20.

[0014] In this bearingless motor pump 1, an impeller 50 having a rotor core 55 is magnetically supported (magnetic levitation) by a stator 71 of a motor unit 70 and rotationally driven (magnetic drive), and discharges the fluid sucked from the fluid inlet 21 from the fluid outlet 24.

[0015] Each member of the pump unit 10 can be made of resin, metal, or other materials according to the application. Depending on the application, for example, when the bearingless motor pump 1 is used as a pump for biopharmaceuticals (a pump for transporting, for example, blood or other fluids for manufacturing biopharmaceuticals), it is preferable that each member of the pump unit 10 be made of one or more types of resin.

[0016] Such resins can employ one or more resins selected from polyethylene (PE), low-density polyethylene (LDPE), ultra-low-density polyethylene (ULDPE), ethylene vinyl acetate (EVA), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polypropylene (PP), polyurethane (PU), polyvinylidene fluoride (PVDF), acrylonitrile butadiene styrene (ABS), polyacrylic, polycarbonate (PC), polyether ether ketone (PEEK), or silicone. In many applications, polytetrafluoroethylene (PTFE) and perfluoroalkoxy polymer (PFA), materials known under the trade name Teflon (registered trademark), can also be selected as suitable resins.

[0017] The impeller 50 is configured such that the rotor (impeller) of the pump and the rotor of the motor are integrated, and is magnetically levitated and magnetically driven (magnetically rotated) by the stator 71 without passing through a main shaft supported by a bearing. The impeller 50 is configured as an integrated rotor that functions as both the rotor of the pump and the rotor of the motor. The bearingless motor pump 1 constituted by the integrated rotor provides a structural advantage in that it can be configured in a small size and with space savings. Note that the fact that the rotor (impeller) of the pump and the rotor of the motor are integrated does not necessarily mean that the entire impeller 50 is integrally formed. This includes cases where the entire impeller 50 (or the impeller main body 51 described later) is integrally formed, and cases where a plurality of members are connected to finally form the impeller 50 (or the impeller main body 51) into an integrated configuration.

[0018] As shown in FIGS. 2A to 2E, the impeller 50 includes a cylindrical impeller main body 51, a suction port 52 provided on the upper surface 56 of the impeller main body 51 for sucking fluid, one or a plurality of discharge ports 54 (a plurality of discharge ports 54 in this embodiment) provided on the outer peripheral surface 58 of the impeller main body 51 for discharging the fluid sucked from the suction port 52, and a rotor core 55 provided on the lower surface side (below the discharge port 54) of the impeller main body 51. Each discharge port 54 is connected to the suction port 52 via a discharge flow path 54A (FIGS. 2A, 2E) provided in the impeller main body 51.

[0019] As shown in FIG. 2E, the discharge flow path 54A connected to each discharge port 54 extends in a spiral shape from the radially inner side to the radially outer side. As shown in FIG. 2E, each discharge flow path 54A is formed between adjacent vanes 54C by a vane (blade part) 54C formed as a raised part that rises from the upper surface of the main board 51A of the impeller main body 51. The vane 54C constitutes a discharge flow path forming part. In this embodiment, the outer peripheral surface of the vane 54C constitutes a part of the outer peripheral surface 58 of the impeller main body 51. The upper surface of the main board 51A constitutes the bottom surface 54B of the discharge flow path 54A between the vanes 54C. In the configuration shown in FIGS. 2A to 2E, the bottom surface 54B of the discharge flow path 54A is the impeller 5 It extends to the outer surface 58 (discharge port 54) of 0.

[0020] In the impeller 50, fluid is drawn in through the suction port 52 and discharged through multiple discharge channels 54A from multiple discharge ports 54.

[0021] The rotor core 55 is a component that is magnetically supported and driven (rotated) by magnetic interaction with the stator 71, and the impeller 51 is magnetically supported and driven by the magnetic support and driving of the rotor core 55. In this embodiment, the rotor core 55 is embedded in the resin that constitutes the impeller body 51. In other embodiments, part or all of the rotor core 55 may not be covered by the resin that constitutes the impeller body 51. The rotor core 55 is made of a permanent magnet or other magnetic material with high coercivity of magnetic polarization, having multiple magnetic poles. The rotor core 55 may be a single ring-shaped component, or it may be made of multiple pieces arranged in a ring shape as a whole. The shape of the rotor core 55 is not limited to a ring shape, and may be other shapes such as a disc shape. The rotor core 55 may be configured in which a permanent magnet or other magnetic material with high coercivity of magnetic polarization is embedded in a non-magnetic material component.

[0022] The impeller body 51 can be a molded product made of, for example, resin. In this embodiment, the impeller body 51 is configured as a cylindrical member having an upper surface 56, a lower surface 57, and an outer peripheral surface 58 of the impeller 50. In this embodiment, as shown in Figure 2E, the impeller body 51 comprises a main plate (first part) 51A and a side plate (second part) 51B. In this embodiment, the main plate 51A is formed as a component constituting the main part of the impeller body 51 (a component on which the vanes 54C and rotor core 55 are arranged), and the side plate 51B is formed as a lid member that closes the upper side of the main plate 51A. The main plate 51A is provided with the lower surface 57 and outer peripheral surface 58 of the impeller 50 (impeller body 51), and a discharge channel 54A and a discharge port 54 are provided. The side plate 51B is provided with the upper surface 56 of the impeller 50 (impeller body 51) and the intake port 52.

[0023] The impeller body 51 is not limited to the above configuration and can be configured in any way. For example, the impeller body 51 may be made up of multiple components combined in a configuration other than that described above, or the entire body may be integrally molded. For example, the main plate 51A may be made up of multiple components combined. Also, the side plate 51B may be omitted. If the side plate 51B is omitted, the suction port 52 will be at the radially inner end of the discharge passage 54A between the vanes (blades) 54C.

[0024] As shown in Figures 2A to E, the outer circumferential surface 58 of the impeller body 51 is provided with notches or grooves 60 along the circumferential direction. The notches 60 are for adjusting the axial thrust (in this embodiment, an axial thrust acting from below to above) generated by the pressure difference between the fluid on the upper surface 56 side and the fluid on the lower surface 57 side of the impeller 50 when the impeller rotates. The notches 60 may be formed, for example, around the entire circumference of the outer circumferential surface 58 of the impeller body 51. The notches 60 may be formed, for example, below the discharge port 54 and adjacent to the discharge port 54. As shown in Figure 2A, the notches 60 have, for example, an inclined surface 62 that slopes downward from the radially inward to the radially outward side of the impeller body 51. In the example shown in Figure 2A, the notch 60 has a horizontal surface 61 extending perpendicular to the rotation axis A of the impeller body 51, and an inclined surface 62 that slopes downward from the radially inward to the radially outward direction of the impeller body 51.

[0025] In the example shown in Figure 2A, the horizontal plane 61 and the inclined surface 62 intersect at the bottom of the notch 60. However, the horizontal plane 61 and the inclined surface 62 may be connected via a vertical plane (not shown) extending in the direction of the rotation axis A. Furthermore, the inclined surface 62 may be made up of multiple inclined surfaces with different angles joined together. In addition, some or all of the surfaces constituting the notch 60 may be curved. It may also be a surface. For example, the above vertical surface may be a curved surface that protrudes horizontally and radially inward from the impeller body 51.

[0026] The motor unit 70 shown in Figure 1 is an electromagnetic rotary drive device and, together with the impeller 50 (rotor) of the pump unit 10, constitutes the bearingless motor pump 1. The motor unit 70 is equipped with a stator 71. The stator 71 is equipped with a plurality of stator cores 72 arranged in a circle so as to surround the impeller 50 in a plan view, and coils 76 wound around each stator core 72 below the impeller 50. Each stator core 72 is equipped with a longitudinal rim 73 and a transverse rim 74 connected to one end of the longitudinal rim 73, the tip (tip surface) of which constitutes the stator pole. The protruding portion 41 of the pump unit 10 (rotor core 55 of the impeller 50) is inserted into the center of the roughly circular space surrounded by the tips (tip surfaces) of the transverse rims 74. In addition, a stator yoke 75 made of magnetic material is provided at the lower end of the longitudinal rim 73. The motor unit 70 may include motor casings 78 and 80 that house the stator 71 (stator core 72, coil 76, stator yoke 75). The motor casings 78 and 80 may be filled with resin to further secure the stator 71 with the resin. The motor unit 70 may also include a control unit and / or power supply unit (not shown) for the bearingless motor pump 1.

[0027] During the assembly of the bearingless motor pump 1, the protruding portion 41 of the pump unit 10 (the rotor core 55 of the impeller 50) is inserted into the center of a roughly circular space surrounded by the tip (tip surface) of the lateral rim 74 of the motor unit 70, thereby attaching the pump unit 10 to the motor unit 70 and completing the bearingless motor pump 1.

[0028] In this bearingless motor pump 1, by passing an electric current through the coil 76, the rotor core 55 of the impeller 50 and the stator 71 magnetically support (magnetically levitate) and rotate (magnetically drive) the impeller 50. The rotation of the impeller 50 transports the fluid drawn in from the fluid inlet 21 and discharged from the fluid outlet 24. Furthermore, by passing an electric current through the coil 76, the radial position of the impeller 50 (rotor) (for example, in the x-axis and y-axis directions) is actively controlled. On the other hand, the position of the impeller 50 (rotor) in the direction of the rotation axis A (z-axis direction) is not controlled, and in these directions, the impeller 50 (rotor) is passively held by magnetic resistance (magnetic shear force and restoring torque). In this embodiment, the force holding the position of the impeller 50 (rotor) tends to be weak, and disturbances due to axial thrust in the z-axis direction, which is not actively controlled, are suppressed by providing a notch 60 in the impeller 50. The operation of the bearingless motor pump 1 (rotation and position control of the impeller 50) is controlled, for example, by a control unit (not shown).

[0029] Axial thrust in the direction of rotation axis A is generated by the difference between the fluid pressure on the upper surface 56 side of the impeller 50 (force acting on the upper surface 56 from the fluid) and the fluid pressure on the lower surface 57 side (force acting on the lower surface 57 from the fluid) (pressure difference between the upper and lower surfaces). For example, in an impeller 50 without a notch 60, the fluid pressure on the lower surface 57 side is greater than the fluid pressure on the upper surface 56 side, generating an axial thrust that raises the impeller 50 upward (from the lower surface 57 side to the upper surface 56 side). According to the impeller 50 of this embodiment, the fluid flow that exits the discharge port 54 of the impeller 50, hits the wall of the pump casing 20 (the part other than the outlet passage 23), and returns, hits the notch 60, and generates a downward axial force component. This downward axial thrust reduces the upward axial thrust that pushes the impeller 50 upward, maintaining the position of the impeller 50 in its normal position, or preventing or suppressing contact between the impeller 50 and the upper inner wall surface of the pump casing 20.

[0030] In a particularly preferred embodiment, the pump unit 10 may be designed as a disposable device for single use, and the stator 71 may be designed as a reusable device. It can be inserted into the motor unit 70. That is, the bearingless motor pump 1 comprises a pump unit 10 designed as a disposable device for single use and a stator 71 (or motor unit 70) designed as a reusable device for multiple uses. The pump unit 10 may also be designed as a disposable device for a predetermined number of uses, which is fewer than the number of uses of the reusable stator 71 (or motor unit 70).

[0031] (Second Embodiment) Figure 3A is a cross-sectional view of the pump unit according to the second embodiment. Figure 3B is a downward perspective view of the impeller of the pump unit according to the second embodiment. Figure 3C is an exploded perspective view of the impeller of the pump unit according to the second embodiment.

[0032] The bearingless motor pump 1 of this embodiment differs from the bearingless motor pump 1 of the first embodiment in that the impeller 50 is provided with a balance hole 59. Since the other structural aspects are the same as those of the first embodiment, only the differences from the first embodiment will be described below, and the similarities will be omitted.

[0033] In this embodiment, a balance hole 59 is provided that passes through the center of the impeller 50. The balance hole 59 is configured such that, for example, its central axis coincides with the rotation axis A. The balance hole 59 is formed concentrically with the suction port 52. As shown in Figure 3A, one end of the balance hole 59 opens into the center of the lower surface 57 of the impeller 50, and the other end of the balance hole 59 is in fluid communication with the suction port 52 and a plurality of discharge passages 54A. The opening on the lower surface 57 of the balance hole 59 also functions as a second suction port. In this impeller 50, fluid drawn in from the suction port 52 and the balance hole 59 is discharged from a plurality of discharge ports 54 via the plurality of discharge passages 54A. In order to suppress losses due to fluid leakage (reduction in pump efficiency) caused by providing the balance hole 59, it is preferable that the diameter of the balance hole 59 be selected to be smaller than the diameter of the suction port 52. However, the diameter of the balance hole 59 may be greater than or equal to the diameter of the suction port 52.

[0034] In this configuration, the balance hole 59 provides fluidic communication between the upper surface 56 and the lower surface 57 of the impeller 50, thereby reducing the pressure difference between the fluid on the upper surface 56 and the fluid on the lower surface 57. Therefore, in this configuration, the upward axial thrust acting on the impeller 50 can be reduced by the balance hole 59 in addition to the notch 60. By combining the notch 60 and the balance hole 59, the upward axial thrust acting on the impeller 50 can be effectively suppressed while suppressing an increase in the diameter of the balance hole 59 (while suppressing leakage loss due to the balance hole 59).

[0035] (Third embodiment) Figure 4A is an upper perspective view of the impeller of the pump unit according to the third embodiment. Figure 4B is a side view of the impeller of the pump unit according to the third embodiment. Figure 4C is a lower perspective view of the impeller of the pump unit according to the third embodiment.

[0036] The bearingless motor pump 1 of this embodiment differs from the bearingless motor pump 1 of the first embodiment in that a notch 60 is formed that penetrates the bottom surface 54B of the discharge passage 54A (and the bottom surface of the discharge port 54). The bottom surface of the discharge port 54 is the bottom surface of the discharge port 54, or the bottom surface near the discharge port 54, within the bottom surface 54B of the discharge passage 54A. The other structures are the same as in the first embodiment, so only the differences from the first embodiment will be described below, and the same aspects as in the first embodiment will not be described.

[0037] In this embodiment, as shown in Figures 4A to 4C, the notch 60 penetrates the bottom surface 54B of the discharge channel 54A (and the bottom surface of the discharge port 54) on the outer circumference of the impeller 50. In the first embodiment, as shown in Figures 2A to 2E, the bottom surface 54B of the discharge channel 54A extends to the outer circumference 58 of the impeller 50. On the other hand, in this embodiment, as is clear from comparing Figure 4B and Figure 2C, the notch 60 penetrates the bottom surface 54B of the discharge channel 54A on the outer circumference of the impeller 50, and it can be seen that there is no bottom surface 54B of the discharge channel 54A near the outer circumference 58 of the impeller 50. Note that if the notch 60 extends around the entire circumference of the impeller 50, as shown in Figure 4B, the portion of the vane 54C below the notch 60 will also have its thickness reduced by the thickness of the bottom surface 54B of the discharge channel 54A.

[0038] According to the third embodiment, in addition to the effects of the first embodiment, the dimensions of the notch 60 (width, especially the dimensions of the slope 62) can be made larger, which can further improve the effect of suppressing axial thrust. Furthermore, since the bottom surface 54B of the discharge passage 54A is generally considered to have little influence on the fluid flow, even if the bottom surface 54B is absent in the notch 60, it is considered that the effect on the performance of the impeller 50 (pump 1) will be small.

[0039] (Fourth Embodiment) Figure 5 is a downward perspective view of the impeller of the pump unit according to the fourth embodiment. The bearingless motor pump 1 of this embodiment is the bearingless motor pump 1 of the third embodiment, with a balance hole 59 provided in the impeller 50. In other words, the bearingless motor pump 1 of this embodiment is the bearingless motor pump 1 of the first embodiment, with a balance hole 59 provided in the impeller 50 as in the second embodiment, and a notch 60 formed through the bottom surface 54B of the discharge passage 54A (and the bottom surface of the discharge port 54) as in the third embodiment. According to this embodiment, in addition to the effects of the first embodiment, the effects of the second embodiment (axial thrust reduction effect due to the balance hole 59) and the effects of the third embodiment (effect of reducing and improving axial thrust due to the increased size of the notch 60) can be achieved.

[0040] (Other embodiments) (1) The specific configuration of the impeller 50 is not limited to the configuration described above, and the configuration of providing the notch in the above embodiment can be applied to any impeller configuration that does not have a main shaft supported by a bearing. (2) The specific configuration of the bearingless motor pump 1 is not limited to the configuration described above, and the configuration of providing a notch in the impeller can be applied to any bearingless motor pump configuration that has an impeller without a main shaft supported by a bearing. For example, the motor described above is a configuration called a temple motor, but the motor is not limited to a temple motor, and may be a general radial gap motor, for example. (3) In the above, the fluid inlet 21 of the pump 1 and the suction port 52 of the impeller 50 are arranged to open upward, but the fluid inlet 21 of the pump 1 and the suction port 52 of the impeller 50 may be configured to face downward, to the side, or in other directions.

[0041] The present invention can also be described in the following embodiments. These embodiments may be combined with each other.

[0042] [1] According to one embodiment, a bearingless motor pump impeller comprising: a cylindrical impeller body having a first surface, a second surface opposite to the first surface, and an outer peripheral surface between the first surface and the second surface; an intake port provided on the first surface of the impeller body for drawing in fluid; one or more discharge ports provided on the outer peripheral surface of the impeller body for discharging the fluid drawn in from the intake port; and a rotor core provided on the impeller body, the An impeller is provided, wherein a notch is provided on the outer surface of the impeller body along the circumferential direction of the impeller body. The outer surface of the impeller body does not have to be a smooth curved surface; for example, it may be an outer surface with steps, or any shape of outer surface located between the first and second surfaces. The one or more discharge ports may include multiple discharge ports. The impeller body may include multiple vanes. Discharge channels connected to the discharge ports may be formed between adjacent vanes, and discharge ports may be formed at the outer ends of adjacent vanes.

[0043] In this configuration, by providing a notch along the circumferential direction on the outer surface of the impeller, the axial thrust that the impeller receives from the fluid can be reduced. For example, by directing the fluid flow that returns after the fluid discharged from the impeller hits the casing to the notch, the axial thrust that the impeller receives from the fluid can be reduced. That is, the fluid that hits the notch generates an axial thrust in the opposite direction to the axial thrust (force that tries to move the impeller in the rotation axis direction) caused by the fluid pressure difference between the two end faces of the impeller without a notch (for example, between the upper and lower faces), thereby reducing the axial thrust acting on the impeller. As a result, the position of the impeller can be stabilized during operation, and contact between the impeller and the casing wall can be suppressed or prevented.

[0044] [2] In one embodiment, the notch may be adjacent to the discharge port on the second surface side of the discharge port in the rotation axis direction of the impeller.

[0045] In this configuration, the fluid discharged from the impeller can be effectively directed towards the notch as it returns after hitting the casing.

[0046] [3] In one embodiment, the notch may be formed between the discharge port and the rotor core in the direction of rotation of the impeller.

[0047] This configuration allows for the formation of a notch while avoiding the discharge port and rotor core, thereby improving the design flexibility of the notch depth dimension (dimension in the impeller diameter direction).

[0048] [4] In one embodiment, the notch may include an inclined surface that slopes toward the second surface from the radially inward side of the impeller toward the radially outward side.

[0049] In this configuration, when reducing the axial thrust toward the first surface of the impeller, the fluid flow hitting the inclined surface of the notch generates an axial thrust toward the second surface, thereby reducing the axial thrust acting on the impeller.

[0050] [5] In one embodiment, the notch may be formed to penetrate the bottom surface of the discharge port and the discharge channel connected to the discharge port.

[0051] This configuration allows for a larger notch width (dimension in the direction of the impeller's rotation axis), thereby increasing the effect of suppressing axial thrust.

[0052] [6] In one embodiment, the impeller body may further include a balance hole that opens on the second surface of the impeller body and is fluidly connected to the intake port and the one or more discharge ports.

[0053] In this configuration, the balance hole connecting the first and second surfaces reduces the pressure difference between the two end faces of the impeller. In other words, axial thrust can be reduced not only by the notch but also by the balance hole.

[0054] [7] In one embodiment, the impeller body further comprises a balance hole opening on the second surface of the impeller body and being fluidly connected to the intake port and the one or more discharge ports, wherein the notch is formed to penetrate the discharge port and the bottom surface of the discharge channel connected to the discharge port.

[0055] In this configuration, the balance hole connecting the first and second surfaces reduces the pressure difference between the two end faces of the impeller. That is, axial thrust can be reduced not only by the notch but also by the balance hole. Furthermore, the width of the notch (the dimension in the direction of the impeller rotation axis) can be increased, thereby increasing the effect of suppressing axial thrust.

[0056] [8] In one embodiment, the notch is formed continuously around the entire circumference of the impeller body.

[0057] This form allows for easy creation of notches.

[0058] [9] In one embodiment, the one or more discharge ports may include a plurality of discharge ports, and the plurality of discharge ports may be provided along the circumferential direction of the impeller body.

[0059] This configuration makes it possible to reduce the axial thrust acting on the impeller, which includes multiple discharge ports, from the fluid.

[0060]

[10] In one embodiment, a pump unit is provided comprising: an impeller of any of the above-mentioned types; and a pump casing having a fluid inlet for drawing in the fluid and a fluid outlet for discharging the fluid, and housing the impeller.

[0061] According to this configuration, a bearingless motor pump can be constructed by combining the pump unit with the stator (motor unit), thereby realizing a bearingless motor pump that exhibits the effects described above. Furthermore, since the pump unit is a separate unit from the stator (motor unit), the stator (motor unit) can be configured as a reusable device, while the pump unit can be configured as a disposable device used only once or for a predetermined number of times.

[0062]

[11] In one embodiment, a bearingless motor pump is provided, comprising: a pump unit having any of the above-mentioned impellers and a pump casing that houses the impeller and has a fluid inlet for drawing in the fluid and a fluid outlet for discharging the fluid; and a motor unit including a stator arranged to surround the impeller of the pump unit, which acts magnetically on the rotor core of the impeller to magnetically support the impeller and rotate the impeller.

[0063] This configuration makes it possible to realize a bearingless motor pump that achieves the effects described above.

[0064]

[12] According to one embodiment, the pump casing has an internal space for housing the impeller, the internal space having a first internal space provided on the fluid inlet side in the rotation axis direction of the impeller and having a first radial dimension, and a second internal space formed continuous with the first internal space and further away from the fluid inlet than the first internal space and having a second radial dimension smaller than the first radial dimension, and when the impeller is rotating, the suction port of the impeller is in the first internal space and at least a part of the notch is in the second internal space, and the impeller moves from the normal position in the rotation axis direction The notch may be configured such that when it is displaced toward the first internal space, the entire notch is exposed within the first internal space.

[0065] In this configuration, when the impeller is operating in its normal position, the fluid flow exiting the impeller's discharge port, hitting the casing, and returning does not directly hit the notch, thereby suppressing the generation of excessive axial thrust toward the second surface due to the notch. At the same time, when the impeller is displaced from its normal position toward the fluid inlet in the direction of rotation axis due to the axial thrust from the fluid, the fluid exiting the impeller's discharge port, hitting the casing, and returning directly hits the notch, thereby generating a sufficiently large axial thrust in the opposite direction to the axial thrust that displaces the impeller toward the fluid inlet.

[0066] While embodiments of the present invention have been described above, the embodiments of the invention described above are for the purpose of facilitating understanding of the present invention and do not limit it. The present invention can be modified and improved without departing from its spirit, and of course, the present invention includes equivalents thereof. Furthermore, any combination of embodiments and modifications is possible to the extent that at least some of the above-mentioned problems can be solved or at least some of the effects can be achieved, and any combination or omission of each component described in the claims and specification is possible.

[0067] All disclosures of Japanese Patent Application No. 2023-212932 (Patent Document 1), including the specification, claims, drawings, and abstract, are incorporated into this Application by reference. [Explanation of symbols]

[0068] 1. Bearingless motor pump (pump) 10 Pump Units 20 Pump casing 21 Fluid inlet 22 Inlet channel 23 Outlet channel 24 Fluid outlet 25 Interior space 26 1st interior space 27 Second interior space 41 Protrusion 50 Impeller 51 Impeller body 51A main plate 51B Side plate 52 Inlet 54 Discharge port 54A Discharge channel 54B Bottom 54C Vane (wing part) 55 Rotor Core 56 Top 57 Bottom side 58 Outer surface 59 Balance Hole 60 notches 61 horizontal plane 62 Slope 70 Motor Unit 71 Stator 72 Stator Cores 73 Longitudinal rim 74 Lateral Rim 75 York 76 coils 78, 80 Motor Casing

Claims

1. The impeller of a bearingless motor pump, A cylindrical impeller body having a first surface, a second surface opposite to the first surface, and an outer peripheral surface between the first surface and the second surface, The impeller body has a first surface provided with a suction port for drawing in fluid, One or more discharge ports are provided on the outer circumferential surface of the impeller body for discharging the fluid sucked in from the intake port, The rotor core provided on the impeller body, Equipped with, An impeller having a notch provided on the outer surface of the impeller body along the circumferential direction of the impeller body.

2. In the impeller according to claim 1, An impeller in which the notch is adjacent to the discharge port on the second surface side in the direction of rotation of the impeller.

3. In the impeller according to claim 2, An impeller in which the notch is formed between the discharge port and the rotor core in the direction of rotation of the impeller.

4. In the impeller according to claim 1, The impeller includes an inclined surface that slopes toward the second surface from the radially inward to the radially outward direction of the impeller.

5. In the impeller according to claim 1, An impeller in which the aforementioned notch is formed to penetrate the bottom surface of the discharge port and the discharge channel connected to the discharge port.

6. In the impeller according to claim 1, The impeller body further comprises a balance hole that opens on the second surface of the impeller body and is fluidly connected to the intake port and the one or more discharge ports.

7. In the impeller according to claim 1, The impeller body further comprises a balance hole that opens on the second surface of the impeller body and is fluidly connected to the intake port and the one or more discharge ports, An impeller in which the aforementioned notch is formed to penetrate the bottom surface of the discharge port and the discharge channel connected to the discharge port.

8. In the impeller according to claim 1, The aforementioned notch is formed continuously around the entire circumference of the impeller body, in an impeller.

9. In the impeller according to claim 1, The one or more discharge ports include a plurality of discharge ports, An impeller in which the plurality of discharge ports are provided along the circumferential direction of the impeller body.

10. It is a pump unit, An impeller according to any one of claims 1 to 9, A pump casing having a fluid inlet for drawing in the fluid and a fluid outlet for discharging the fluid, and housing the impeller, A pump unit equipped with the following features.

11. It is a bearingless motor pump, A pump unit comprising an impeller according to any one of claims 1 to 9, and a pump casing having a fluid inlet for drawing in the fluid and a fluid outlet for discharging the fluid, and housing the impeller, A motor unit including a stator arranged to surround the impeller of the pump unit, which acts magnetically on the rotor core of the impeller to magnetically support the impeller and rotate the impeller, A bearingless motor pump equipped with this feature.

12. In the bearingless motor pump according to claim 10, The pump casing has an internal space for housing the impeller, The internal space comprises a first internal space having a first radial dimension and provided on the fluid inlet side in the rotation axis direction of the impeller, and a second internal space formed continuous with the first internal space and further away from the fluid inlet than the first internal space, and having a second radial dimension smaller than the first radial dimension. A bearingless motor pump configured such that, when the impeller is rotating, the suction port and discharge port of the impeller are located within the first internal space and at least a portion of the notch is located within the second internal space when the impeller is in its normal position, and when the impeller is displaced from its normal position toward the first internal space along the axis of rotation, the entire notch is exposed within the first internal space.

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