JP7182729B2 - impeller and pump equipped with the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to an impeller and a pump having the same.

2. Description of the Related Art There is known a pump provided with a magnetic bearing that non-contactly supports the load of a rotor provided with an impeller of a pump device by magnetic force, and a drive unit that drives the rotor by magnetic force (see, for example, Patent Document 1). In this pump, a bearing magnet is provided on the outer circumference of the rotor, and a magnetic core as a stator member is arranged on the inner circumference of the housing facing the bearing magnet to form a magnetic bearing.

JP 2006-226390 A

However, the conventional pump disclosed in Patent Document 1 employs magnetic bearings instead of mechanical bearings, so that the rotor is supported by magnetic levitation in a non-contact state. Therefore, depending on the load of the pump and the type of fluid transferred, the bearing mechanism is directly affected by the fluid, causing the impeller to shift in the axial direction (axial thrust) or tilt in the radial direction (radial direction). (radial thrust), the rotor may be damaged together with the impeller, or a so-called step-out may occur.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an impeller capable of reducing axial thrust and radial thrust, and a pump having the impeller.

An impeller according to the present invention is an impeller provided at one axial end side of a cylindrical rotor body and constituting a rotor together with the rotor body, wherein a blade support is provided at one axial end side of the rotor body. an impeller base having a surface; and a plurality of curved surfaces extending from the radially inner side to the outer side of the blade supporting surface in the direction opposite to the rotation direction of the rotor on the blade supporting surface of the impeller base. and the impeller base of the plurality of blades are provided on the opposite side in the axial direction, cover the outer peripheral side portions of the plurality of blades, and cover the inner peripheral side portions of the plurality of blades in the center an annular plate-shaped front shroud having an exposed hole formed therein, wherein the front shroud is characterized in that the inner diameter of the hole is larger than the outer diameter of the impeller base.

A pump according to the present invention includes a rotor including a cylindrical rotor body, an impeller provided at one axial end of the rotor body, a magnetic bearing that supports the rotor by magnetic force, and a rotor that rotates. and a pump mechanism including the impeller, wherein the pump mechanism defines a rear casing that forms an accommodation space that accommodates the rotor body and an accommodation space that accommodates the impeller. the impeller includes an impeller base provided on one end side in the axial direction of the rotor body and having a blade support surface; A plurality of blades provided so as to extend curvedly in a direction opposite to the rotational direction of the rotor from the radially inner side to the outer side of the rotor, and the impeller base of the plurality of blades are provided on the opposite side in the axial direction an annular plate-shaped front shroud provided to cover the outer peripheral side portions of the plurality of blades and having a hole formed in the center for exposing the inner peripheral side portions of the plurality of blades; The front shroud is characterized in that the inner diameter of the hole is larger than the outer diameter of the impeller base.

In one embodiment of the invention, the inner diameter of the front shroud hole is 110% to 135% of the outer diameter of the impeller base.

In another embodiment of the present invention, the impeller base has an R surface on the outer peripheral edge on the blade supporting surface side.

In still another embodiment of the present invention, the plurality of blades are arranged on a surface opposite to the blade support surface of the portion of the front shroud located inside the hole so as to face the rotational direction. It has a sloping first tapered portion.

In still another embodiment of the present invention, the plurality of blades have a second tapered portion on the blade support surface side surface that is inclined in the direction opposite to the rotation direction.

In yet another embodiment of the present invention, the impeller base is cylindrical and has a plurality of lateral holes that allow the inner peripheral portion and the outer peripheral portion to communicate with each other.

According to the present invention, axial thrust and radial thrust can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal cross-sectional view schematically showing the overall configuration of a pump provided with an impeller according to one embodiment of the invention, with a part cut away; It is the perspective view which notched one part which shows roughly the rotor containing the same impeller. It is a top view which shows the same impeller roughly. 4 is a cross-sectional view taken along line AA' of FIG. 3; FIG. 4 is a cross-sectional view taken along line BB' of FIG. 3; FIG. It is a rear view which shows the same impeller roughly. FIG. 2 is a partially enlarged longitudinal sectional view of FIG. 1;

Hereinafter, impellers and pumps having the same according to embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the following embodiments do not limit the invention according to each claim, and not all combinations of features described in the embodiments are essential to the solution of the invention. do not have. In addition, in the following embodiments, the same or corresponding components are denoted by the same reference numerals, and redundant explanations are omitted. In addition, in the embodiments, there are cases where the scales and dimensions of each component are shown in a state that does not correspond to the actual ones, and where some components are omitted.

FIG. 1 is a longitudinal cross-sectional view, partially cut away, schematically showing the overall configuration of a pump equipped with an impeller according to an embodiment of the present invention.
As shown in FIG. 1, a pump 100 according to the present embodiment is used as a magnet pump for fluid transfer, and includes a rotor 120, a magnetic bearing 110 that supports the rotor 120 by magnetic force without contact, and the rotor 120. It has a magnetic coupling type drive mechanism 130 that drives to rotate, and a pump mechanism that includes an impeller 190 that is attached to one end side of the rotor 120 in the axial direction. The pump 100 also includes a controller 210 as a control unit that controls at least the entire pump mechanism.

In the following description, the rotation axis (Z-axis) direction of the rotor 120 is the Z-axis direction (also referred to as the axial direction or Z direction), and the radial direction of the rotor 120 is the X-axis direction and the Y-axis direction (radial direction, X direction and the Y direction), the direction of rotation about the X axis is called the Θ direction, and the direction of rotation about the Y axis is called the Φ direction. In the Θ direction and Φ direction, the direction of rotation indicated by the arrow in the figure is the + (plus) side, and the opposite side is the - (minus) side. It is also assumed that the X-axis, Y-axis and Z-axis are orthogonal to each other. Also, the right side of the paper is the front side of the pump 100, and the left side is the rear side. Furthermore, regarding the Z-axis direction, the front side is the + (plus) side and the rear side is the - (minus) side.

First, the overall configuration of the pump 100 will be described. The pump 100 is formed in a cylindrical shape as a whole and has a front casing 141 on one side (front side) in the Z-axis direction. The front casing 141 defines a pump chamber A1, which is a circular housing space for housing the impeller 190, and has a cylindrical suction port 151 communicating with the pump chamber A1 at the front central portion. The front casing 141 also has a discharge port 152 on its side surface that communicates with the pump chamber A1.

A rear casing 142 is connected to the rear end of the front casing 141 in a sealed state with an O-ring (not shown), for example. The rear casing 142 forms an enclosed space A including the pump chamber A1 together with the front casing 141. As shown in FIG. In addition, the rear casing 142 forms a cylindrical space (receiving space) A2 protruding rearward.

The radially outer side (peripheral side) of the rear casing 142 on the rear side is covered with a cylindrical housing 143 . A motor housing 134a having a rear cover 154 attached to the rear side thereof is connected to the rear side of the housing 143, and a pump base 153 that supports the pump 100 is provided below them.

The closed space A accommodates the rotor 120 in a floatable state (non-contact support). The rotor 120 is made entirely of a non-magnetic material such as a resin material. An annular bearing/driven portion 121 as a main body is integrally formed. Details of the impeller 190 will be described later. Alternatively, the bearing/driven portion 121 of the rotor 120 may be manufactured first, and the impeller 190 may be manufactured with respect to this bearing/driven portion 121 by secondary molding. It may be integrally formed by providing a screw mechanism that can be combined and adopting a detachable and integrally configurable structure. The impeller 190 of the rotor 120 is accommodated in the pump chamber A1 inside the front casing 141, and constitutes a pump mechanism together with the pump chamber A1.

On the other hand, the rear casing 142 has a cylindrical projection projecting rearward from its central portion, and the bearing/driven portion 121 of the rotor 120 is housed in a cylindrical space A2 inside the cylindrical projection. A flanged cylindrical stator base 144 is provided inside the housing 143 . The stator base 144 supports the bearing stator 112 of the magnetic bearing 110 to be described later between the rear casing 142 and the rear casing 142 .

A magnetic bearing 110 that supports the rotor 120 by magnetic force is provided on the outer peripheral side of the bearing/driven portion 121 of the rotor 120 . A drive mechanism 130 for driving the rotor 120 is provided on the inner peripheral side of the bearing/driven portion 121 of the rotor 120 .

The magnetic bearing 110 includes a ring-shaped bearing rotor member 111 made of a magnetic material mounted on the outer peripheral side of the bearing/driven portion 121 of the rotor 120, and a bearing rotor member 111, for example, outside the bearing rotor member 111 in the radial direction. and a bearing stator 112 arranged at a predetermined interval.

The bearing rotor member 111 includes, for example, a bearing magnet 113 made of a neodymium magnet formed in an annular shape, and concentrically with the bearing magnet 113, and axially sandwiching both end surfaces of the bearing magnet 113 in the axial direction (Z-axis direction). and a pair of yokes 114 and 115 made of annular electromagnetic soft iron arranged in a manner.

The bearing magnet 113 is magnetized so that, for example, the north pole and the south pole face each other in the axial direction and have the same pole over the entire circumferential direction. The bearing magnet 113 supplies bias magnetic flux (not shown) to a magnetic circuit formed by a bearing stator core 117 of the bearing rotor member 111 and the bearing stator 112, which will be described later.

On the other hand, a plurality of bearing stators 112 are arranged, for example, at four locations in the circumferential direction of the bearing rotor member 111 at angles of 90°. Of these bearing stators 112, for example, a pair of bearing stators 112 opposed in the X-axis direction controls the position of the rotor 120 in the X-axis direction and the angle in the Φ direction under the control of the controller 210, A pair of bearing stators 112, which are in contact with each other, controls the Y-axis position and the angle of the rotor 120 in the .theta.-direction. These bearing stators 112 also control the height of the rotor 120 in the Z-axis direction.

Displacement sensors (not shown) capable of detecting displacement of the bearing rotor member 111 in the radial direction and each rotational direction are provided on the stator base 144 and form an angle of 45° with the bearing stator 112 (that is, the X-axis). and the Y-axis direction at an angle of 45°).

These displacement sensors include, for example, eddy current sensors, but are not limited to this, and various sensors can be employed. Also, the number of bearing stators 112 is not limited to the number described above, and various forms such as 6, 8, 10, 12, and 16 may be employed. In addition, although illustration is omitted, the displacement sensor is provided, for example, on the stator base 144 or the like so as to face the bearing/driven portion 121 in the axial direction, together with the displacement sensor described above. Various sensors capable of detecting rotational displacement are also included. Note that the arrangement mode and number of the displacement sensors and the like are not limited to this, and various forms can be adopted.

In the case of the pump 100 of this embodiment, the impeller 190 is arranged on one side (front side) of the rotor 120. Therefore, when the rotor 120 is tilted with respect to the Z axis, it rotates at a position close to the impeller 190 on the Z axis. The rotor 120 is tilted about the center. For this reason, although not shown, if a displacement sensor is arranged, for example, at a position away from the impeller 190, preferably at a position in the center of the bearing/driven portion 121 in the Z-axis direction, the displacement sensor can detect the rotor Since it is possible to detect the position of 120 in the X-axis direction and the angle in the Φ direction, and the position in the Y-axis direction and the angle in the Θ direction, it is possible to sufficiently control the inclination of the rotation axis by two-axis control. .

The bearing stator 112 has a bearing stator core 117 made of a magnetic material such as laminated electromagnetic steel sheets, and a bearing coil 118 wound around the bearing stator core 117 . The longitudinal cross-sectional shape of the bearing stator core 117 is, for example, substantially C-shaped (U-shaped) with an open end on the bearing rotor member 111 side.

Specifically, the bearing stator core 117 has a vertical cross-sectional shape that extends, for example, in the Z-axis direction perpendicular to the facing direction (radial direction) with the bearing rotor member 111, and serves as a first portion around which the bearing coil 118 is wound. , a pair of second portions extending toward the bearing rotor member 111 from both end portions of the first portion in the Z-axis direction and then approaching each other in the Z-axis direction; and a pair of third portions extending toward the bearing rotor member 111 side. In other words, the bearing stator core 117 has a C-shaped vertical cross-section that should originally extend linearly toward the bearing rotor member 111 from both ends in the Z-axis direction of the first portion around which the bearing coil 118 is wound. It can be said that it has a pair of hook-shaped portions at the open end portion of and has a shape in which the portions on the open end side are close to each other.

With such a shape, as shown in the figure, the length of the bearing coil 118 in the Z-axis direction is longer than the distance between the facing surfaces in the Z-axis direction of the pair of third portions on the open end side of the bearing stator core 117 . It is possible to make it larger. That is, the distance between the tips of the open ends can be made smaller than the length of the wound portion of the bearing coil 118 in the Z-axis direction. In addition, the width of the open end side of the bearing stator core 117, that is, the distance between the facing surfaces in the Z-axis direction of the pair of third portions and the surface on the opposite side is smaller than the original length of the bearing stator core 117 in the Z-axis direction. It has a size approximately equal to the length of the bearing rotor member 111 in the Z-axis direction.

The drive mechanism 130 includes a driven magnet 131 as an annular driven member mounted on the inner peripheral side of the bearing/driven portion 121 of the rotor 120, and a driven magnet 131, for example, and a predetermined magnet inside the driven magnet 131 in the radial direction. and a drive magnet 132 as a drive unit arranged with a gap therebetween.

Further, the driving mechanism 130 has a motor shaft 133 to which the driving magnet 132 is attached to the tip portion and rotatably supported by a bearing 135, and a driving motor 134 that drives the motor shaft 133 to rotate. In this embodiment, the driven magnet 131 and the driving magnet 132 are composed of, for example, neodymium magnets magnetized to have two or four radial poles. Also, in this embodiment, the drive magnet 132 and the motor shaft 133 are shown to have substantially the same diameter, but they do not necessarily have to have the same diameter.

The controller 210 detects the displacement of the rotor 120 in each direction and each rotation direction based on detection signals from various sensors including the displacement sensor described above, and adjusts the bearing coil 118 of the bearing stator 112 of the magnetic bearing 110 accordingly. finely control the current flowing through the As a result, the position of the rotor 120 in the X-axis direction, the angle in the Φ direction, the position in the Y-axis direction, the angle in the Θ direction, and the height in the Z-axis direction are controlled in real time to correct the rotational position.

The controller 210 processes signals from, for example, a driver board 211 equipped with a MOS-FET for driving the bearing coil 118 of the magnetic bearing 110, a CPU board 212 for controlling the operations of the magnetic bearing 110 and the drive mechanism 130, and various sensors. It also includes an encoder board 213 that controls a magnetic encoder (not shown).

Note that the controller 210 is arranged on the rear side of the stator base 144 . A cooling fan 169 as a rotating blade is attached to the motor shaft 133 of the drive motor 134 on the rear side of the controller 210 . These controller 210 and cooling fan 169 are arranged inside the housing 143 .

Next, the impeller 190 of the rotor 120 of the pump 100 will be explained.
2 is a partially cutaway perspective view schematically showing the rotor 120 including the impeller 190, FIG. 3 is a top view schematically showing the impeller 190, and FIG. 4 is a sectional view taken along line AA' of FIG. 5 is a cross-sectional view taken along the line BB' of FIG. 3, and FIG. 6 is a rear view schematically showing the impeller 190. As shown in FIG.
The impeller 190 of the rotor 120 includes an impeller base 191 , a plurality of blades 192 and a front shroud 193 .

The impeller base portion 191 is a thin flanged cylindrical member made of a non-magnetic material such as a resin material that can be integrally connected to the bearing/driven portion 121 as the rotor body. As shown in the figure, the impeller base 191 may be detachably attached to the bearing/driven portion 121 by screw portions 191a and 121a, or may be integrally attached to the bearing/driven portion 121 by secondary molding or the like. It may be a configuration.

The impeller base 191 has an annular blade support surface 191b on the front shroud 193 side. The plurality of blades 192 extend in a curved shape in a direction opposite to the direction of rotation of the rotor 120 indicated by arrows in FIGS. Thus, for example, five are provided here. An annular plate-shaped front shroud (front side plate) 193 is provided on the front side (front side) of the plurality of blades 192 opposite to the impeller base portion 191 in the Z-axis direction.

The front shroud 193 covers the outer peripheral side portions of the plurality of blades 192 from the front side, and has a circular center hole (hole) 193a in the central portion. The inner peripheral side portions of the plurality of blades 192 are exposed from the center hole 193a. The inner diameter D2 of the center hole 193a is larger than the outer diameter T2 of the impeller base portion 191 . This is to secure a flow path area for transfer fluid that is sucked from the suction port 151 of the pump 100, passes through the center hole 193a and moves to the rear casing 142 side. In order to further secure this flow passage area, the impeller base 191 has a rounded surface 191c on the outer peripheral edge of the blade support surface 191b, as shown in FIG.

The plurality of blades 192 has a first tapered portion 194 that is inclined in the direction of rotation on the surface of the portion located inside the center hole 193a (see FIG. 5). In addition, the plurality of blades 192 has a second tapered portion 195 that is inclined in the direction opposite to the direction of rotation on the back surface of the portion arranged on the back side (rear side) of the front shroud 193 (see FIG. 5). .

In other words, the first tapered portion 194 is formed by a tapered surface that descends obliquely in the rotational direction from an upstream end portion 192a on the front side of the portion exposed from the center hole 193a of the blade 192 in the rotational direction. . In other words, the second taper portion 195 is a taper that rises obliquely in the direction opposite to the rotation direction from the downstream end portion 192b in the rotation direction on the back side of the portion formed on the back side of the front shroud 193 of the blade 192. It consists of faces.

As shown in FIG. 4, when the impeller base 191 is connected to the bearing/driven portion 121, the inner space of the rotor 120 (the inner space A3 of the bearing/driven portion 121: see FIG. 4) and the front A plurality of side holes (horizontal holes) 191d are formed to communicate with the accommodation space (pump chamber A1) of the casing 141. As shown in FIG. These side holes 191d have a hole shape such as a circular, elliptical, or flat elliptical shape, and extend radially from the center of the rotation axis of the rotor 120 through the impeller base 191. There are four.

Next, the action of the pump 100 having the impeller 190 configured in this manner will be described.
In the case of a pump in which the rotor is supported by magnetic bearings, it is difficult to mechanically restrict the movement of the rotor, which causes problems such as axial movement and inclination of the rotor. When the suction port 151 is located in front of the pump chamber A1 as in the pump 100 of the present embodiment, the pressure of the pump chamber A1 on the side of the suction port 151 decreases due to the suction of the transfer fluid. If the impeller 190 is of an open type without the front shroud 193, the rotor 120 moves largely to the + side (forward side) in the axial direction and also tilts in the radial direction. Also in the case of the closed type in which shrouds are provided on both sides of the blades 192 and the semi-open type in which the rear shrouds are provided on the rear side of the blades 192, the rotor 120 moves to the + side in the axial direction.

In this respect, according to the pump 100 of the present embodiment, the impeller 190 adopts a semi-open type in which an annular front shroud 193 is provided in front of the blades 192. A pressure drop caused by an increase in the flow velocity of the fluid generates a force that tends to move the rotor 120 toward the rear casing 142 side. Therefore, this force is balanced with the forward moving force due to the pressure drop on the suction port 151 side, and the rotor 120 can be prevented from moving in the axial direction. In addition, tilting of the rotor 120 can be prevented by the inertial action of the front shroud 193 when it rotates.

Here, if the inner diameter D2 of the center hole 193a of the front shroud 193 is smaller than the outer diameter T2 of the impeller base portion 191, the passage cross-sectional area of the transfer fluid transferred from the suction port 151 of the pump 100 to the rear casing 142 side is ensured. Therefore, the pressure on the suction port 151 side does not decrease, and the amount of movement of the rotor 120 in the negative (rear) direction in the axial direction becomes too large, and the rotor 120 may come into contact with the rear casing 142 .

On the other hand, if the inner diameter D2 of the center hole 193a of the front shroud 193 is extremely larger than the outer diameter T2 of the impeller base 191, a sufficient decompression effect cannot be obtained on the rear surface side of the front shroud 193, and the rear casing of the rotor 120 cannot be obtained. The movement to the 142 side and the tilt prevention function are deteriorated.

According to experiments conducted by the present inventors regarding this point, the inner diameter D2 of the center hole 193a of the front shroud 193 is 110% or more and 135% or less, preferably 113% or more and 120%, of the outer diameter T2 of the bearing/driven portion 121. It turned out that it is desirable to be formed so that it may become as follows.

Further, the decompression effect on the rear surface side of the front shroud 193 also changes depending on the outer diameter D1 of the front shroud 193 . According to experiments conducted by the inventors, it was found that the smaller the outer diameter D1 of the front shroud 193, the greater the inclination of the rotor 120. FIG. This is probably due to the fact that the transfer fluid has the highest flow velocity and the lowest pressure in the vicinity of the discharge port 152 . This is because if the outer diameter D1 of the front shroud 193 is not sufficiently large with respect to the pump chamber A1, it is difficult to balance the pressure in the vicinity of the discharge port 152 . According to experiments by the present inventors, the outer diameter (outer diameter of the impeller 190) D1 of the front shroud 193 is 85% or more and less than 100% of the inner diameter T1 of the housing space (pump chamber A1) of the front casing 141. It was found that it is desirable to form the thickness preferably to be 90% or more and 94% or less.

The movement of the rotor 120 in the axial direction can also be adjusted by adjusting the angles of the first tapered portion 194 and/or the second tapered portion 195 formed on the blades 192 . That is, when the first tapered portion 194 and/or the second tapered portion 195 are inclined at inclination angles η1 and η2 with respect to the rotation direction as shown in FIG. Since the propulsive force toward the side is generated, the rotor 120 moves to the negative side in the axial direction. According to experiments by the present inventors, the first tapered portion 194 is formed, for example, so that the inclination angle η1 with respect to the surface (horizontal plane) of the front shroud 193 is in the range of 15° to 30°. is desirable. Further, it is desirable that the second tapered portion 195 is formed so that the angle of inclination η2 with respect to the rear surface (horizontal plane) of the front shroud 193 is in the range of 15° to 30°. However, the first tapered portion 194 and/or the second tapered portion 195 may not be provided when fine adjustment of the rotor 120 in the axial direction is unnecessary.

Further, if a side hole 191d penetrating laterally of the impeller base portion 191 corresponding to the back side of the impeller 190 is provided, there is an effect of suppressing the movement of the impeller 190 toward the front casing 141 side (positive axial direction). That is, the flow of transfer fluid generated by the impeller 190 is discharged from the discharge port 152, and as indicated by the arrow in FIG. (accommodation space) including A2).

The flow of transfer fluid that has flowed from the pump chamber A1 to the rear casing 142 side passes through the outer peripheral side of the bearing/driven portion 121 in the cylindrical space A2, passes through the inner space A3 of the bearing/driven portion 121, and flows through the impeller 190. By forcefully pulling out from the side hole 191 d provided on the back side, the effect of lowering the pressure of the rotor 120 on the back side (rear side) of the impeller 190 is produced. On the rear side, the pressure-receiving area multiplied by the internal pressure near the bottom surface of the rear casing 142 (the bottom surface of the cylindrical space A2) moves the impeller 190 toward the front casing 141 (positive axial direction). becomes. Therefore, by lowering the pressure on the rear side of the impeller 190 through the side holes 191d, it is possible to suppress the amount of movement in the positive axial direction.

Although the embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. This novel embodiment can be embodied in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

For example, in the above-described embodiment, the impeller 190 has four side holes 191d each having a circular, elliptical or flattened elliptical shape, and has five blades 192. Since various forms can be taken depending on the type of fluid, the design performance of the pump 100, etc., the number, shape, and arrangement are not limited to the above. Further, in the above embodiment, the impeller 190 of the rotor 120 supported by magnetic bearings has been described as an example, but the rotors supported by mechanical bearings are also applicable. Even in this case, there is an effect that unnecessary loads in the axial direction and inclination are not generated.

100 pump 110 magnetic bearing 120 rotor 121 bearing/driven part (rotor body)
130 drive mechanism 190 impeller 191 impeller base 191b blade support surface 191d side hole 192 blade 193 front shroud 193a center hole 194 first tapered portion 195 second tapered portion 210 controller

Claims (10)

An impeller provided at one axial end side of a cylindrical rotor body supported in a non-contact manner by the magnetic force of a magnetic bearing, and constituting a rotor together with the rotor body,
an impeller base having a blade supporting surface provided on one end side of the rotor body in the axial direction;
a plurality of blades provided on the blade support surface of the impeller base so as to extend in a curved shape from the radially inner side to the outer side of the blade support surface in a direction opposite to the rotational direction of the rotor;
A hole provided on the opposite side of the impeller base of the plurality of blades in the axial direction, covering the outer peripheral side portion of the plurality of blades, and exposing the inner peripheral side portion of the plurality of blades at the center and an annular plate-shaped front shroud formed with
The front shroud has an inner diameter of the hole larger than an outer diameter of the impeller base,
The impeller is a semi-open type in which the plurality of blades on the blade supporting surface side of the front shroud are exposed,
The impeller base portion is formed in a cylindrical shape, and the inner peripheral portion and the outer peripheral portion are radially communicated in the radial direction at a position near the blade support surface to flow transfer fluid from the inner peripheral portion to the outer peripheral portion. An impeller characterized by having a plurality of lateral holes. The impeller according to claim 1, wherein the inner diameter of the hole of the front shroud is 110% to 135% of the outer diameter of the impeller base. 3. The impeller according to claim 1, wherein the impeller base has an R surface on the outer peripheral edge on the blade supporting surface side. The plurality of blades have a first tapered portion that is inclined in the direction of rotation on a surface opposite to the blade supporting surface of a portion of the front shroud that is arranged inside the hole. The impeller according to any one of claims 1 to 3, characterized by: 5. The plurality of blades according to any one of claims 1 to 4, wherein the plurality of blades have a second tapered portion on the blade supporting surface side surface that is inclined in a direction opposite to the rotation direction. impeller. a rotor including a cylindrical rotor body and an impeller provided at one axial end of the rotor body;
a magnetic bearing that supports the rotor by magnetic force;
a drive mechanism that drives the rotor to rotate;
a pump mechanism including the impeller;
A pump comprising
The pump mechanism is
A casing having a rear casing forming a housing space for housing the rotor main body and a front casing forming a housing space for housing the impeller,
The impeller is
an impeller base provided on one end side of the rotor body in the axial direction and having a blade supporting surface;
a plurality of blades provided on the blade support surface of the impeller base so as to extend in a curved shape from the radially inner side to the outer side of the blade support surface in a direction opposite to the rotational direction of the rotor;
A hole provided on the opposite side of the impeller base of the plurality of blades in the axial direction, covering the outer peripheral side portion of the plurality of blades, and exposing the inner peripheral side portion of the plurality of blades at the center and an annular plate-shaped front shroud formed with
The front shroud has an inner diameter of the hole larger than an outer diameter of the impeller base,
The plurality of blades directly face the rear casing,
An inner peripheral gap is provided between the inner peripheral side of the rotor body and the rear casing,
An outer peripheral side gap communicating with a space between the front shroud and the rear casing is provided between the outer peripheral side of the rotor body and the rear casing,
A cylindrical space is provided between the other end of the rotor body in the axial direction and the bottom surface of the rear casing, and communicates the inner peripheral gap and the outer peripheral gap,
The impeller base is formed in a cylindrical shape with an inner space communicating with the inner peripheral gap, and the inner peripheral portion and the outer peripheral portion are radially communicated with each other in the radial direction at a position in the vicinity of the blade support surface to form the inner peripheral space. A pump comprising a plurality of lateral holes that allow transfer fluid to flow from the outer circumference of the pump . 7. The pump according to claim 6, wherein the inner diameter of the hole of the front shroud is 110% to 135% of the outer diameter of the impeller base. 8. The pump according to claim 6, wherein the impeller base has an R surface on the outer peripheral edge on the blade supporting surface side. The plurality of blades have a first tapered portion that is inclined in the direction of rotation on a surface opposite to the blade supporting surface of a portion of the front shroud that is arranged inside the hole. The pump according to any one of claims 6 to 8, characterized by: 10. The plurality of blades according to any one of claims 6 to 9, wherein the blade supporting surface has a second tapered portion that is inclined in a direction opposite to the direction of rotation. pump.

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