JP2010174670A - Motor pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor pump capable of enabling stable operation, by suppressing wobble of an impeller. <P>SOLUTION: The motor pump includes an impeller 1 in which a plurality of permanent magnets 5 are buried, a motor stator 6 for generating magnetic field that acts on the plurality of permanent magnets 5, a casing 2 having a suction port 13 and a discharge port 12, for accommodating the impeller 1 and a motor stator 6, and one bearing 10 for supporting the impeller 1. The discharge port 12 and the impeller 1 are arranged coaxially, and, a plurality of return blades 18 for directing liquid discharged from the impeller 1 to the discharge port 12 are arranged on back side of the impeller 1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a motor pump that rotates an impeller embedded with a permanent magnet by a magnetic field generated by a motor stator.

  As a conventional example of a motor pump that rotates an impeller embedded with a permanent magnet by a magnetic field generated by a motor stator, a pump described in Patent Document 1 is known. The motor pump described in Patent Document 1 includes an impeller with a permanent magnet embedded therein and a motor stator disposed opposite the impeller, and the impeller is rotated by a magnetic field generated by the motor stator. It is supposed to be. The impeller is accommodated in a casing and is rotatably supported by one spherical bearing. The spherical bearing is a so-called dynamic pressure bearing, and can support the impeller in a tiltable manner while rotatably supporting the impeller.

  Since this spherical bearing can tolerate the tilting of the impeller according to the load applied to the impeller, there is an advantage that no local load is applied to the spherical bearing. In addition, since the impeller is supported by only one spherical bearing, even if the casing or the impeller is deformed due to the temperature change of the liquid, there is no deviation of the shaft center between the bearings. There is no effect.

  However, the spherical bearing, on the other hand, has a problem that the rotation of the impeller tends to become unstable. That is, if the external force (liquid pressure) applied to the impeller is not uniform, the impeller fluctuates and the impeller vibrates. In particular, at the time of start-up or low-speed rotation, the impeller may be greatly inclined and contact the casing.

Japanese Patent No. 2544825

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a motor pump capable of suppressing stable wobbling of an impeller and enabling stable operation.

  In order to solve the above-described problems, an aspect of the present invention includes an impeller in which a plurality of permanent magnets are embedded, a motor stator that generates a magnetic field that acts on the plurality of permanent magnets, and an inlet and an outlet A motor pump including a casing for housing the impeller and the motor stator, and a bearing for supporting the impeller, wherein the discharge port and the impeller are arranged concentrically. A plurality of return vanes for guiding the liquid discharged from the impeller to the discharge port are arranged on the back side of the impeller.

In a preferred aspect of the present invention, the bearing has a radial surface that supports a radial load of the impeller and a thrust surface that supports a thrust load of the impeller, and the radial surface is an axis of the impeller. And the thrust surface is perpendicular to the axis of the impeller.
In a preferred aspect of the present invention, the suction port, the discharge port, and the impeller are arranged concentrically.

In a preferred aspect of the present invention, a uniform gap is formed between the outer peripheral surface of the magnet housing portion of the impeller in which the plurality of permanent magnets are embedded and the casing.
In a preferred aspect of the present invention, an annular taper channel having a diameter gradually increasing toward the discharge side is formed on the discharge side of the gap.
In a preferred aspect of the present invention, at least one return flow path is formed between the bearing and the casing to return a part of the liquid pressurized by the impeller to the liquid inlet of the impeller. It is characterized by.

  According to the present invention, since the discharge port and the impeller are arranged concentrically, the liquid discharged from the impeller forms a uniform flow toward the discharge port. Therefore, a uniform pressure from the liquid is applied to the outer peripheral portion of the impeller, and as a result, the impeller can be prevented from wobbling.

It is sectional drawing which shows the motor pump which concerns on one Embodiment of this invention. It is the figure which looked at the motor pump shown in FIG. 1 from the arrow II direction. It is the figure which looked at the return blade fixed to the side plate from the discharge side of FIG. It is a top view which shows the permanent magnet currently embed | buried under the impeller. It is a top view which shows a motor stator. It is the VI-VI sectional view taken on the line shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a sectional view showing a motor pump according to an embodiment of the present invention, and FIG. 2 is a view of the motor pump shown in FIG. The motor pump includes an impeller 1 in which a plurality of permanent magnets 5 are embedded, a motor stator 6 that generates magnetic force acting on the permanent magnets 5, and a casing 2 that houses the impeller 1 and the motor stator 6. And. The casing 2 is basically composed of a pump casing 2A that houses the impeller 1 and a motor casing 2B that houses the motor stator 6. The pump casing 2A and the motor casing 2B are fixed to each other by a plurality of connecting bolts 8 shown in FIG. An O-ring 9 as a seal member is provided between the pump casing 2A and the motor casing 2B.

  The impeller 1 is rotatably supported by a single bearing 10. This bearing 10 is a sliding bearing formed in an annular shape, and is disposed so as to surround a liquid inlet 1 a formed in the center of the front surface of the impeller 1. Here, the front surface of the impeller 1 is the surface on the suction side of the impeller 1, that is, the surface on the side where the liquid inlet 1 a is provided, and the rear surface of the impeller 1 is the front surface of the impeller 1. The opposite surface, that is, the discharge side surface of the impeller 1 is referred to.

  The bearing 10 has a radial surface 10 a that supports the radial load of the impeller 1 and a thrust surface 10 b that supports the thrust load of the impeller 1. The radial surface 10 a is parallel to the axis of the impeller 1, and the thrust surface 10 b is perpendicular to the axis of the impeller 1. Tilt of the impeller 1 is regulated by the bearing 10, and contact between the impeller 1 and the casing 2 is prevented. A spiral groove (not shown) is formed on the surface of the impeller 1 facing the radial surface 10a and the thrust surface 10b.

  The impeller 1 is formed of a nonmagnetic material that is slippery and difficult to wear. For example, a resin such as Teflon (registered trademark) or PPS (polyphenylene sulfide) or ceramic is preferably used. The pump casing 2 </ b> A and the motor casing 2 </ b> B can also be formed from the same material as the impeller 1.

  When the impeller 1 rotates, a fluid dynamic pressure is generated between the radial surface 10 a and the thrust surface 10 b and the impeller 1, whereby the impeller 1 is supported by the bearing 10 in a non-contact manner. The bearing 10 is made of a material having excellent wear resistance such as ceramic or carbon. In addition, you may provide the impeller 1 in the sliding contact member which opposes the radial surface 10a and the thrust surface 10b. In this case, the spiral groove is formed in the sliding contact member instead of the impeller 1. As with the bearing 10, the sliding contact member is preferably formed from a material having excellent wear resistance, such as ceramic or carbon.

  A discharge port 12 is formed in the pump casing 2A, and a suction port 13 is formed in the motor casing 2B. The liquid inlet 1 a of the impeller 1 communicates with the suction port 13. The suction port 13, the bearing 10, the impeller 1, and the discharge port 12 are arranged concentrically. That is, the center of the suction port 13 and the center of the discharge port 12 are located on the central axis Cr of the impeller 1. A plurality of return blades 18 are provided on the back side of the impeller 1. These return blades 18 are disposed between the substantially disk-shaped side plate 19 and the pump casing 2A.

  FIG. 3 is a view of the return blade fixed to the side plate as viewed from the discharge side of FIG. As shown in FIG. 3, the return blade 18 extends in a spiral shape toward the outer peripheral direction. By these return blades 18, the liquid discharged from the rotating impeller 1 is smoothly guided to the discharge port 12. In the present embodiment, since the impeller 1 and the discharge port 12 are arranged concentrically, the liquid forms a uniform flow from the outer periphery of the impeller 1 toward the discharge port 12 through the return blade 18. Therefore, the pressure of the liquid that acts on the impeller 1 is uniform over the entire circumference of the impeller, thereby preventing the impeller 1 from wobbling.

  FIG. 4 is a plan view showing the permanent magnet 5 embedded in the impeller 1. As shown in FIG. 4, the plurality of permanent magnets 5 are arranged in an annular shape, and S poles and N poles are alternately arranged. In the present embodiment, each permanent magnet 5 has a sector shape, and the number of permanent magnets 5 is eight (that is, eight poles). As shown in FIG. 1, an annular magnet yoke (magnetic body) 15 is embedded in the impeller 1 adjacent to the plurality of permanent magnets 5. The permanent magnet 5 is disposed on the suction side of the magnet yoke 15. The permanent magnet 5 and the motor stator 6 are arranged so as to face each other. The motor stator 6 is arranged on the suction side with respect to the impeller 1. The motor stator 6 is disposed in the motor casing 2 </ b> B, and a space in which the motor stator 6 is accommodated is closed by a motor cover 16.

  FIG. 5 is a plan view showing the motor stator 6. As shown in FIG. 5, the motor stator 6 has a stator core 6A having a plurality of teeth 6a and a stator winding 6B wound around these teeth 6a. The teeth 6a and the stator winding 6B are arranged in an annular shape. In this embodiment, the stator winding 6B is wound around each of the six teeth 6a, and the number of magnetic poles is six. The centers of the permanent magnets 5 arranged in a ring and the centers of the teeth 6a arranged in a ring coincide with each other. Further, the permanent magnet 5 and the motor stator 6 are arranged concentrically with the impeller 1, the bearing 10, the suction port 13, and the discharge port 12.

  Three lead wires 17 (see FIG. 2) are connected to the stator winding 6B, and the terminals of the lead wires 17 are connected to a drive circuit (not shown). This drive circuit is a device that controls the timing of the current supplied to each stator winding 6B using a switching element. More specifically, the drive circuit controls the timing of the current supplied to each stator winding 6B based on the position of the rotating permanent magnet 5. Examples of the method for detecting the position of the permanent magnet 5 include a method using a position sensor such as a Hall element, and a method using a counter electromotive force generated in the stator winding 6B without using a position sensor. The motor pump according to the present embodiment may employ either a sensor driving method using a position sensor or a sensorless driving method that does not use a position sensor.

  The drive circuit described above appropriately switches the application of a direct current to the stator winding 6B based on the position of the permanent magnet 5, whereby the permanent magnet 5, that is, the impeller 1 rotates. When the impeller 1 rotates, the liquid is introduced from the suction port 13 to the liquid inlet 1 a of the impeller 1. The liquid is pressurized by the rotation of the impeller 1 and discharged from the discharge port 12. While the impeller 1 is transferring the liquid, the back surface of the impeller 1 is pressed to the suction side (that is, toward the suction port 13) by the pressurized liquid. Since the bearing 10 is disposed on the suction side of the impeller 1, the bearing 10 supports the thrust load of the impeller 1 from the suction side. According to the structure which concerns on this embodiment, since the impeller 1 can be supported non-contactingly with the one bearing 10, the compact motor pump which does not generate | occur | produce a particle is realizable.

  A gap 20 is formed between the outer peripheral surface of the magnet housing portion (portion where the permanent magnet 5 is embedded) of the impeller 1 and the inner peripheral surface of the pump casing 2A. The size δ of the gap 20 is uniform in the circumferential direction and the axial direction of the impeller 1. That is, the gap 20 between the outer peripheral surface of the magnet housing portion of the impeller 1 and the portion of the inner peripheral surface of the pump casing 2A facing the outer peripheral surface of the magnet housing portion is uniform. 1 indicates the width of the gap 20 in the axial direction. In the gap 20, the dynamic pressure of the liquid generated by the rotation of the impeller 1 acts uniformly on the impeller 1 as a journal bearing (radial bearing). As a result, the impeller 1 rotates stably.

  6 is a cross-sectional view taken along line VI-VI in FIG. A plurality (four in FIG. 6) of return flow paths 22 are provided between the bearing 10 and the motor casing 2B. The return flow path 22 extends from the gap between the front surface of the impeller 1 and the motor casing 2 </ b> B to the liquid inlet 1 a of the impeller 1. Part of the liquid pressurized by the impeller 1 passes through the clearance 20 between the outer peripheral surface of the impeller 1 and the pump casing 2A, the clearance between the front surface of the impeller 1 and the motor casing 2B, and the return flow path 22. It passes in order and is returned to the liquid inlet 1a of the impeller 1.

  The return flow path 22 is provided to supply a sufficient liquid to the bearing 10. If there is not enough liquid between the bearing 10 and the impeller 1, the bearing 10 may be burned. In particular, when the liquid in the gap between the front surface of the impeller 1 and the motor casing 2 </ b> B is boiled due to heat generation or fluid friction of the motor stator 6, the liquid between the bearing 10 and the impeller 1 is exhausted. In the present embodiment, by providing the return flow path 22, a liquid flow is always formed in the gap between the front surface of the impeller 1 and the motor casing 2 </ b> B. Therefore, an increase in the temperature of the liquid is suppressed, and a sufficient liquid for supporting the impeller 1 can be supplied to the bearing 10.

  As shown in FIG. 1, a taper channel 23 is formed on the downstream side (discharge side) of the gap 20. The tapered flow path 23 has a shape in which the diameter gradually increases toward the discharge side. Since the liquid discharged from the impeller 1 has a rotational component, it is pressed against the inner peripheral surface of the pump casing 2A by centrifugal force. Therefore, by setting the flow path from the liquid outlet of the impeller 1 to the return blade 18 as the taper flow path 23, the liquid is forced to flow downstream by the action of centrifugal force and is smoothly guided to the return blade 18. .

  The motor pump according to the present embodiment is a so-called in-line type pump in which the suction port 12, the impeller 1, and the discharge port 12 are arranged concentrically. Since this type of pump can be relatively easily incorporated into an existing pipe or the like, it has a feature of wide application range. Further, since the impeller 1 and the discharge port 12 are arranged concentrically, the liquid discharged from the rotating impeller 1 forms a uniform flow and is discharged from the discharge port 12. Therefore, the external force acting on the impeller 1 from the outside in the radial direction is uniform over the entire circumference of the impeller 1 and the rotation of the impeller 1 is stabilized. Furthermore, in this embodiment, since the tilting of the impeller 1 is regulated by the bearing 10, the impeller 1 can be rotated more stably.

  The embodiment described above is described for the purpose of enabling the person having ordinary knowledge in the technical field to which the present invention belongs to implement the present invention. Various modifications of the above embodiment can be naturally made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Therefore, the present invention should not be limited to the described embodiments, but should be the widest scope according to the technical idea defined by the claims.

DESCRIPTION OF SYMBOLS 1 Impeller 2 Casing 5 Permanent magnet 6 Motor stator 8 Connecting bolt 9 O-ring 10 Bearing 12 Discharge port 13 Suction port 15 Magnet yoke 16 Motor cover 17 Lead wire 18 Return blade 19 Side plate 20 Clearance 22 Return channel 23 Tapered channel

Claims (6)

An impeller with a plurality of permanent magnets embedded therein;
A motor stator that generates a magnetic field acting on the plurality of permanent magnets;
A casing having a suction port and a discharge port, and housing the impeller and the motor stator;
A motor pump comprising one bearing for supporting the impeller,
The discharge port and the impeller are arranged concentrically,
A motor pump, wherein a plurality of return vanes for guiding the liquid discharged from the impeller to the discharge port are arranged on the back side of the impeller. The bearing has a radial surface that supports a radial load of the impeller, and a thrust surface that supports a thrust load of the impeller.
The radial surface is parallel to the axis of the impeller;
The motor pump according to claim 1, wherein the thrust surface is perpendicular to an axis of the impeller.   The motor pump according to claim 1, wherein the suction port, the discharge port, and the impeller are arranged concentrically.   2. The motor pump according to claim 1, wherein a uniform gap is formed between an outer peripheral surface of a magnet housing portion of the impeller in which the plurality of permanent magnets are embedded and the casing. .   5. The motor pump according to claim 4, wherein an annular taper passage having a diameter gradually increasing toward the discharge side is formed on the discharge side of the gap.   The at least one return flow path for returning a part of the liquid pressurized by the impeller to the liquid inlet of the impeller is formed between the bearing and the casing. The motor pump described in 1.

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