JP2006112235A - Motor pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor pump capable of preventing bearing wear and particle generation due to sliding even during idling.
A motor pump (10) includes a pump impeller (13), a motor rotor (21) having a permanent magnet (22) on the outer peripheral surface, and a motor stator (25) arranged on the outer periphery of the motor rotor. The axial center (AA line) of the stator core and the axial center (BB line) of the permanent magnet of the motor rotor are arranged at positions shifted in the axial direction. A thrust slide bearing 16 also serving as a liner ring is disposed between the outer peripheral portion of the suction mouth portion 13a of the pump impeller and the pump casing 14, and the slide bearing is provided with a spiral groove groove or a herringbone groove, A pressure bearing was constructed.
[Selection] Figure 1

Description

  The present invention relates to a motor pump equipped with a permanent magnet motor, and is suitable for non-particles (no generation of fine particles) suitable for pumping pure water, chemicals, etc. in an extremely clean environment such as a semiconductor manufacturing process. It relates to a motor pump.

Conventionally, an integral structure motor pump in which a pump impeller is fixed to one end of a motor rotor is known (see, for example, Patent Document 1). In such a motor pump, a motor stator that is can-sealed is arranged on the outer periphery of the motor rotor, a pump casing is arranged around the pump impeller, and the liquid sucked from the suction port of the pump casing is pressurized by the pump impeller. And is discharged from the discharge port of the pump casing.
Japanese Patent Application Laid-Open No. 5-219687

  For example, in a semiconductor manufacturing process, a motor pump having a structure that does not contaminate the liquid as much as possible is used for pumping pure water used for cleaning a semiconductor wafer, pumping various chemicals, and the like. In these motor pumps, a rotating body is generally supported by a sliding bearing, and the bearing is lubricated by a pump handling liquid, that is, a liquid to be pumped. However, during the pump operation, even when liquid is present, particles are generated due to bearing friction due to slight sliding of the bearing.

  Furthermore, when no liquid is present at the time of starting the pump, or when a liquid in which bubbles are mixed is sent, the motor pump is in an idle operation state or a state close to this. At this time, in the sliding bearing, the liquid as a lubricant does not exist or becomes insufficient, and sliding heat is generated, causing problems such as wear of the bearing or generation of a large amount of particles.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a motor pump that can prevent bearing wear and particle generation due to sliding of a rotating body even during idling of the motor pump. .

  The motor pump of the present invention includes a pump impeller disposed in a pump casing, a motor rotor having a permanent magnet integrally formed with the pump impeller on an outer peripheral surface, and a motor disposed on the outer periphery of the motor rotor. A motor pump including a stator, wherein an axial center of a stator core of the motor stator and an axial center of a permanent magnet of the motor rotor are arranged at positions shifted in the axial direction. Is.

  Here, a thrust slide bearing that also serves as a liner ring is disposed between the outer peripheral portion of the suction mouth portion of the pump impeller and the pump casing. The slide bearing is provided with a spiral groove groove or a herringbone groove, A pressure bearing is configured.

  According to the present invention, the axial center of the stator core of the motor stator and the axial center of the permanent magnet of the motor rotor are arranged at positions shifted in the axial direction, so that the bias force in the rotational axis direction is applied to the motor rotor. And can act on the pump impeller. By properly setting this bias force, even during pump operation and in pump operation in the absence of pump handling liquid, dynamic pressure due to liquid or air is formed by the spiral groove of the thrust slide bearing, etc. Since the hydrodynamic bearing is configured, the operation can be performed in a state where the sliding surfaces of the both bearing members configuring the hydrodynamic bearing are not in contact with each other.

  As a result, the generation of particles from the bearing can be prevented, and the gap between the impeller suction port and the pump casing can be minimized during pump operation. Obtainable. Further, even during the idling of the pump, it is possible to prevent problems such as generation of particles accompanying sliding of a bearing portion of a motor pump having a sliding bearing, and wear and damage of the bearing.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows an external appearance of a motor pump according to the present invention, and FIGS. 2 and 3 show details of the structure by sectional views. In addition, in each figure, the same code | symbol is attached | subjected to the member or element which has the same effect | action or function, and the overlapping description is abbreviate | omitted.

  The motor pump 10 of the present invention is a so-called non-particle pump suitable for, for example, pumping pure water or chemicals in a semiconductor manufacturing process, and the liquid contact portion is made of a resin material. Here, the pump casing 14 is made of a resin material, the pump impeller 13 is also made of a resin material such as Teflon (registered trademark), and a spiral fluid passage is formed therein. Therefore, the liquid sucked from the suction port 15 of the pump casing 14 enters the spiral flow path inside the pump impeller 13 from the suction mouth portion 13a of the pump impeller, and is pressurized by the rotation thereof, thereby being the impeller outlet portion. It is discharged from 13b.

  The motor pump 10 includes a pump unit 11 and a motor unit 12. In the pump unit 11, a pump impeller 13 is disposed in a pump casing 14. As will be described in detail later, a brushless DC motor including a permanent magnet type motor rotor 21 is disposed in the motor unit 12.

  The pump impeller 13 is fixed to the end surface of the motor rotor 21 made of resin such as Teflon (registered trademark), and the pump impeller 13 and the motor rotor 21 are integrally formed. A ring-shaped permanent magnet 22 and a rotor back yoke (iron core) 23 are embedded and disposed on the outer peripheral surface side of the motor rotor 21. As shown in FIG. 3, the ring-shaped permanent magnet 22 is magnetized to, for example, four poles.

  A resin rotor can 28 is disposed on the surface of the permanent magnet 22 embedded in the motor rotor 21 so that the surface of the permanent magnet 22 is not exposed. Thereby, also when pumping chemicals, such as an acid and an alkali, the problem of melt | dissolution of a permanent magnet material etc. can be prevented and contamination of a handling liquid can be prevented.

  A motor stator 25 is disposed on the outer periphery of the motor rotor 21 with a clearance X therebetween. The motor stator 25 is fixed to the motor frame 26 on the outer peripheral surface side, and a stator can 27 made of resin is disposed on the inner peripheral surface side. The motor stator 25 includes a stator core 25a made of an iron core and a coil 25b. When an alternating current is applied to the coil 25b of the motor stator 25, the motor rotor 21 having magnetic poles of four permanent magnets is rotationally driven by the space rotating magnetic field formed by the electromagnetic action of the motor stator 25. The integrally fixed pump impeller 13 is driven to rotate.

  As shown in FIG. 2, the axial center (AA line) of the stator core 25a of the motor stator 25 and the axial center (BB line) of the permanent magnet 22 of the motor rotor 21 are arranged at positions shifted in the rotational axis direction. ing. For this reason, a bias force toward the right side in the drawing in the direction of the rotation axis is generated in the motor rotor 21 and the pump impeller 13. Since this bias force is based on the magnetic attraction force between the iron core constituting the stator core 25a and the magnetic poles of the permanent magnet, this bias force always acts even if the coil 25b of the motor stator is not energized.

  In the motor pump 10, a thrust slide bearing that also serves as a liner ring is disposed between the outer peripheral end face of the suction mouth portion of the pump impeller and the pump casing. That is, as shown in FIG. 2, a thrust slide bearing 16 that also serves as a liner ring is disposed between the suction mouth portion 13 a outer peripheral end surface of the pump impeller 13 and the suction pipe 15 a outer peripheral end surface of the pump casing 14. ing. This thrust sliding bearing 16 is similarly provided on the rotating side impeller 13 side with a sliding bearing member 16a made of a non-metallic material such as ceramic (SiC or alumina) and on the fixed side pump casing 14 side. And a sliding bearing member 16b made of a non-metallic material such as ceramic (SiC or alumina), and the sliding surfaces face each other.

  A spiral groove groove or a herringbone groove is provided on the surface of the sliding bearing member 16a, a smooth surface is provided on the surface of the facing sliding bearing member 16b, and a hydrodynamic bearing is configured between the facing sliding surfaces. . That is, when the pump impeller 13 rotates, dynamic pressure due to air or liquid is generated by a spiral groove groove or the like provided on the sliding surface of the sliding bearing member. By this dynamic pressure, the sliding surfaces of the sliding bearing members 16a and 16b are brought into a non-contact state, and the thrust load directed to the right side in the drawing of the rotating body such as the pump impeller 13 is supported without sliding. Can do. The spiral groove groove or the like may be provided on the surface of the sliding bearing 16b, and the surface of the sliding bearing 16a may be a smooth surface.

  As shown in FIG. 2, the stator can 27 has a bottomed cylindrical shape in which the motor rotor 21 is inserted. A column 30 extending in the direction of the rotation axis is disposed on the bottom 27a of the stator can having a bottomed cylindrical shape, and a flange 30a of the column 30 is fixed to the bottom 27a of the stator can 27 by a screw 31. The support column 30 is made of a non-metallic material such as ceramic such as SiC or alumina, has two herringbone grooves on the circumference of the surface in the axial direction, and forms a hydrodynamic bearing.

  The radial sliding bearing portion 32 faces the sleeve 33 disposed on the inner peripheral surface of the motor rotor 21 with a slight clearance. Here, the sleeve 33 is also made of a non-metallic material such as SiC or alumina. Therefore, when the motor rotor 21 rotates, dynamic pressure is generated by air on the surface of the sliding bearing member such as a herringbone groove, and the inner peripheral surface of the sleeve 24 of the motor rotor 21 is supported in a non-contact manner with respect to the radial sliding bearing member 31. Is done.

  Therefore, in the motor pump 10, the motor rotor 21 integrated with the pump impeller 13 is rotatably supported in the radial direction by the radial sliding bearing portion 32, and provided on the outer peripheral end surface of the suction mouth portion of the pump impeller 13. Similarly, the thrust sliding bearing 16 is rotatably supported in the thrust direction. Since these bearings can be supported in a non-contact manner by dynamic pressure due to air or liquid, there is no problem of particle generation or damage to the bearings even during pump operation or during idling of the pump. Is possible.

  In the motor pump 10 of the present invention, as described above, the axial center (AA line) of the stator core 25a of the motor stator 25 and the axial center (BB line) of the permanent magnet 22 of the motor rotor 21 are in the rotational axis direction. Since the motor rotor 21 is disposed at a shifted position, a bias force is applied to the motor rotor 21 toward the right side in the axial direction. Thus, a liner ring mechanism that serves as a thrust slide bearing, that is, a shaft seal mechanism is formed between the outer peripheral end face of the suction mouth portion of the pump impeller and the pump casing.

  In this shaft seal mechanism, the sliding bearing member 16a serves as an impeller ring on the rotating body side, and the sliding bearing member 16b serves as a liner ring on the fixed side. That is, the clearance between the sliding surfaces of the sliding bearing members 16a and 16b is a dynamic pressure against the leakage path of the pump-handed liquid between the volute part 14a that is the high-pressure part and the suction mouth part 13a that is the low-pressure part. A shaft seal mechanism between the rotating side and the fixed side is configured with a minimum gap of only the gap caused by the rising by the bearing. Thereby, generation | occurrence | production of the particle from this bearing part can be prevented, the leakage from the clearance gap between an impeller inlet and a pump casing at the time of a pump operation can be minimized, and efficient pump performance can be obtained.

  That is, even when the pump handling liquid does not exist at the time of starting the pump or the like and the engine is in the idling state, the sliding bearing members 16a and 16b are both slipped by the dynamic pressure bearing mechanism with the appropriate bias force applied. The surface can be operated in a substantially non-contact state, thereby preventing bearing damage and particle generation in the idle operation state.

  The magnitude of the bias force is adjusted by the axial displacement between the axial center (AA line) of the stator core 25a and the axial center (BB line) of the permanent magnet 22 and the strength of the permanent magnet magnetic force. Is possible. By appropriately setting the bias force, the thrust sliding bearing 16 is provided with a spiral groove or the like between the bearing members 16a and 16b even in a pump operation in the absence of pump handling liquid, that is, in an idle operation state. By forming a dynamic pressure bearing by forming dynamic pressure with air or liquid, the sliding surfaces of both bearing members 16a and 16b are in a non-contact state and can be operated with a minimum leakage flow path. it can.

  Therefore, even when the motor pump is started in the absence of the pump handling liquid, or when the handling liquid is interrupted in some state during the pump operation and the pump is idling, the thrust slide bearing 16 is driven by the dynamic pressure of air. The thrust force on the pump impeller 13 side can be received in a non-contact state. Thereby, the problem of generation | occurrence | production of the particle | grains accompanying the sliding of the bearing part of the motor pump which has a sliding bearing, wear of a bearing, and damage at the time of pump idle operation can be prevented.

  The thrust force during the operation of the pump acts in the direction toward the right side in the figure. When a sufficient amount of liquid is present in the pump, liquid exists between the thrust slide bearings 16a and 16b, and the thrust force and bias force are generated between the thrust slide bearings 16a and 16b due to the levitation force of the dynamic pressure bearing. A slight gap is kept against. Thereby, it is possible to obtain a good shaft seal characteristic without generation of particles, and to obtain an efficient pump characteristic.

  The motor stator 25 is covered with a resin stator can 27, the permanent magnet 22 of the motor rotor 21 is similarly covered with a resin rotor can 28, and the pump impeller 13 itself is also made of resin. For this reason, by using a material having resistance to various chemicals such as Teflon (registered trademark) as the resin material, it is possible to transport various chemicals. Further, by using a resin material having high resistance to various chemical solutions, dissolution of the resin material in the pump handling liquid can be prevented, and particle contamination and chemical contamination can be prevented.

  In the above embodiment, an example of a non-particle pump in which the liquid contact portion is made of resin has been described. However, the gist of the present invention is also applied to a general motor pump driven by other types of brushless DC motors. Of course, it is applicable to.

  That is, although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea.

1 is a partially transparent perspective view showing an appearance of a motor pump according to an embodiment of the present invention. It is a longitudinal cross-sectional view along the rotating shaft of the motor pump of FIG. FIG. 3 is a transverse sectional view taken along line AA in FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Motor pump 11 Pump part 12 Motor part 13 Pump impeller 13a Suction mouse | mouth part 13b Impeller exit part 14 Pump casing 15 Suction port 15a Suction pipe 16 Thrust slide bearing 16a, 16b Thrust slide bearing member 17 Discharge port 21 Motor rotor 22 Permanent magnet 23 Back yoke (iron core)
24 Sleeve 25 Motor stator 25a Stator core 25b Coil 26 Motor frame 27 Stator can 27a Stator can bottom 28 Rotor can 30 Strut 30a Flange 31 Screw 32 Radial slide bearing 33 Sleeve X Clearance

Claims (6)

A motor pump comprising a pump impeller disposed in a pump casing, a motor rotor having a permanent magnet integrally formed with the pump impeller on an outer peripheral surface, and a motor stator disposed on the outer periphery of the motor rotor. There,
The motor pump, wherein the axial center of the stator core of the motor stator and the axial center of the permanent magnet of the motor rotor are arranged at positions shifted in the axial direction.   2. The motor pump according to claim 1, wherein a thrust slide bearing that also serves as a liner ring is disposed between an outer peripheral end face of the suction mouth portion of the pump impeller and the pump casing.   2. The motor pump according to claim 1, wherein the motor rotor has a hollow portion at the center of the rotation shaft, and a radial sliding bearing is disposed in the hollow portion.   4. The motor pump according to claim 2, wherein the sliding bearing is provided with a spiral groove groove or a herringbone groove to constitute a dynamic pressure bearing.   4. The motor pump according to claim 2, wherein the sliding bearing is made of a non-metal.   The pump impeller is made of resin, the motor rotor is made of resin, the permanent magnet is embedded in the resin, the outer peripheral surface of the permanent magnet is covered with resin, and the inner peripheral surface of the motor stator The motor pump according to claim 1, wherein the motor pump is coated with a resin.

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