WO2002038964A1

WO2002038964A1 - Motor pump

Info

Publication number: WO2002038964A1
Application number: PCT/JP2001/009680
Authority: WO
Inventors: Yoshio Miyake; Eiji Tsutsui
Original assignee: Ebara Corporation
Priority date: 2000-11-07
Filing date: 2001-11-06
Publication date: 2002-05-16
Also published as: AU2002211011A1; JP2002138990A

Abstract

A centrifugal (non-positive displacement) motor pump suitable for use in a small output area with extremely small water volume, rather simple in structure, and small in size, comprising a tubular motor stator (10), a motor rotor (20) having a permanent magnet (30), formed integral with an impeller (32), and disposed inside the motor stator (10), and a pump casing (44) fixed to the opening end part of a motor casing (12) so as to cover the impeller (32), wherein a dynamic pressure bearing (54) is formed between the front face of the impeller (32) and a spiral groove (52) provided in the internal surface of the pump casing (44) opposed to the front face of the impeller (32).

Description

Description Motor pump Technical field

The present invention relates to a motor pump, and more particularly, to a motor pump suitable for use in an area with a very small amount of water and a small output, using a motor having a permanent magnet on a motor rotor (for example, a DC brushless motor). Background art

In general, positive displacement pumps such as gear pumps and diaphragm pumps are used as pumps incorporated in various devices and used at flow rates of 1 liter or less per minute to several liters per minute. Many. This flow rate range is a region where the value of the specific speed N s is extremely small in the case of a centrifugal pump (non-positive displacement pump). Have difficulty. For example, if a centrifugal pump with a flow rate of 1 liter per minute and a head of 10 meters is designed at a rotation speed of 1200 rotations per minute, the value of the specific speed N s is 67 (mV In general, it is known that the efficiency of a centrifugal pump decreases significantly when the value of the specific speed N s becomes 70 or less. In this case, the impeller outer diameter is about 25 mm.

On the other hand, a gear pump requires two shafts and two sets of bearings to rotate two gears, and is more complicated and expensive than a centrifugal pump. In addition, diaphragm pumps are designed to repeatedly deform a non-metallic flexible diaphragm to send liquid. It is necessary to replace the diaphragm after about an hour of operation. For this reason, when the pump is used by being incorporated into various small devices, there is a problem that maintenance cost is excessively applied.

Therefore, there has been a strong demand for the development of a centrifugal motor pump, which is suitable for use in the area of very small water volume and small output, replacing the positive displacement motor pump.

Here, when the centrifugal pump is designed to rotate at higher speed, the specific speed of the larger value can be secured. That is, if a centrifugal pump with a flow rate of 1 liter per minute and a head of 10 meters is designed at a rotation speed of 1,800,000 revolutions per minute, the value of the specific speed Ns is 101 (m ^The pump efficiency can be expected to be improved to ³ min, m, and min.However, in this case, the outer diameter of the impeller is about 17 mm, and the entire impeller is extremely small, so that the axial thrust load can be supported. It becomes difficult to secure the mounting dimensions of the bearings and the flow area of the impeller suction part.

The present invention has been made in view of the above, and is suitable for use in an area with a very small amount of water and a small output, has a relatively simple structure, and can be made compact. It is intended to provide a pump.

According to a first aspect of the present invention, there is provided a motor rotor having a cylindrical shape, a motor rotor having a permanent magnet, being integrally formed with the impeller, and disposed inside the motor stator, and covering the impeller. And a pump casing fixed to the open end of the motor casing, wherein a dynamic pressure bearing is provided between a front surface of the impeller and a spiral groove provided on an inner surface of the pump casing facing the front surface of the impeller. It is characterized by comprising.

As a result, a dynamic pressure bearing (axia) is compactly attached to the end of the motor rotor. Bearing) can be provided, and the bearing structure is simplified. In addition, dynamic pressure bearings, which are a type of non-contact type bearings, can be expected to have extremely high durability and can also function as a liner, thus reducing the number of parts. Therefore, the design that enables high-speed rotation makes it possible to achieve longer pump life and higher productivity while reducing the size and efficiency of the pump. In this pump, most of the axial load is absorbed by the permanent magnet of the motor rotor and the magnetic attraction of the motor stator.However, a dynamic pressure bearing is used to reinforce the absorption of the axial load. . In a preferred aspect of the present invention, the spiral groove is provided on a bearing plate fixed to a pump casing.

According to a second aspect of the present invention, there is provided a motor stator having a cylindrical shape, a motor rotor having a permanent magnet, formed integrally with the impeller, and disposed inside the motor stator, and covering the impeller. And a pump casing fixed to the open end of the motor casing, the center hole provided in the shaft center of the motor rotor, and the pump casing protruding from the inner surface on the side opposite to the open end of the motor casing. It is characterized in that a radial bearing is formed between the fixed shaft and the fixed shaft.

This eliminates the need for a fixed shaft that penetrates through the suction section of the impeller in the axial direction. It is easy to secure the flow path area of the suction section of the impeller, and even when rotating at high speed. A high-efficiency pump can be realized without generating pumping.

In a preferred aspect of the present invention, the center hole communicates with a communication hole extending from a suction part of the impeller.

As a result, a flow of the handling liquid from the radial bearing portion toward the suction portion of the impeller is generated, and the handling liquid is applied, for example, to the ceramics on both the fixed side and the rotating side. It can be used for lubrication and cooling of the sliding part of the radial bearing part which is formed by applying a magnetic or Teflon resin coating, etc., and can surely lubricate and cool the sliding part. The structure in which the center hole communicates with the communication hole extending from the suction portion of the impeller can also be used as a so-called balance piston that reduces the axial load (axial thrust load) generated on the motor rotor.

According to a third aspect of the present invention, there is provided a motor rotor having a cylindrical shape, a permanent magnet, a motor rotor formed integrally with the impeller and disposed inside the motor stator, and covering the impeller. A pump casing fixed to the open end of the motor casing, extending along the axis of the motor stator, and extending between the motor casing and the pump casing. The suction port of the pump casing is provided at a position eccentric to the axis of the pump casing.

As a result, it is possible to prevent the flow path area of the suction portion of the impeller from being reduced due to the presence of the fixed shaft, and to substantially suppress the occurrence of air accumulation in the suction flow path.

In a preferred aspect of the present invention, when the fixed shaft is used so as to be horizontal with the ground, the axis of the suction port is located closer to the ground than the axis of the fixed shaft. It is configured as follows. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a sectional view of a motor pump according to a first embodiment of the present invention. FIG. 2 is a surface view of a bearing plate constituting the dynamic pressure bearing on a side facing the front of the impeller.

FIG. 3 is a sectional view of a motor pump according to a second embodiment of the present invention. FIG. 4 is a sectional view of a motor pump according to a third embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Next, an embodiment of the present invention will be described with reference to the drawings.

1 and 2, a motor pump shown in _c Figures 1 and 2 show a motor pump of the first embodiment of the present invention, have a cylindrical motor stator 1 0, the motor stator 1 Numeral 0 is integrally embedded in a cup-shaped motor casing 12 having one end closed and the other end opened, for example, by molding a polyester resin. A fixed shaft 14 protruding inward along the axial direction is integrally connected to the motor casing 12 on the inner surface of the motor casing 12 on the side opposite to the opening.

The resin mold of the motor stator 10 is, for example, first applied to the inner periphery of the motor stator 10 in a state where the outer peripheral portion of a silicon steel plate or the like is positioned in a mold, and then molded. It is applied to the outer periphery of the motor stator 10 with the inner periphery of the motor stator 10 positioned in the mold. When the strength of the motor casing 12 is not necessary as in the case of a pump with a low indentation pressure, the outer periphery of the motor stator 10 is not molded and painted. May be.

A substantially cylindrical motor rotor 20 is disposed inside the motor casing 12, and is disposed inside the motor rotor 20 along the axial direction from the side opposite to the opening of the motor casing 12. A center hole 22 is provided which extends to near the center of the motor rotor 20. By fitting the fixed shaft 14 into the center hole 22, a radial bearing portion 24 is formed between the inner peripheral surface of the center hole 22 and the outer peripheral surface of the fixed shaft 14. I have. The inner diameter of the center hole 22 is set to, for example, about 6 mm, and the outer diameter of the fixed shaft 14 is set to be slightly smaller than the inner diameter of the center hole 22, respectively. The ceramics A coating layer 26 is formed by a resin or Teflon resin coating, and a coating layer 28 is formed on the inner peripheral surface of the center hole 22 by a ceramic or Teflon resin coating. , 28 ensure the durability of the fixed shaft 14 and the center hole 22. Instead of the coating layers 26 and 28, for example, a tube made of Teflon having excellent slidability may be used.

With the configuration described above, the fixed shaft that penetrates the suction portion of the impeller 32 below in the axial direction is eliminated, and the flow path area at the suction portion of the impeller 32 is easily secured, and the rotation speed is high. Even without causing cavitation, a highly efficient pump can be realized.

The motor rotor 20 is made of, for example, a polyester resin. Inside the motor rotor 20, a ring-shaped permanent magnet 30 that rotates with the magnetic field generated by the motor stator 10 is provided at a position facing the motor stator 10. It is buried in one.

At the other end of the motor rotor 20 in the axial direction, a closed impeller 32 having a front shroud is integrally connected to the motor rotor 20. Further, a small communication hole 34 having a diameter of, for example, about 1.5 mm is provided in the motor rotor 20 to communicate the center hole 22 with the suction portion of the impeller 32.

As a result, a flow of the handling liquid from the radial bearing portion 24 toward the suction portion of the impeller 32 is generated, and this handling liquid is slid by the coating layers 26, 28 of the radial bearing portion 24. Used for lubrication and cooling of the moving part, it is possible to reliably lubricate and cool the sliding part. The structure in which the center hole communicates with the communication hole extending from the suction portion of the impeller is a so-called balance piston that reduces the axial load (axial thrust load) generated in the motor rotor 20. Can also be used.

At the open end of the motor casing 12, there is provided a pump casing 44 having a suction nozzle 40 and a discharge nozzle 42, and having a shape of a pump which covers the periphery of the impeller 32. It is attached via a plurality of bolts and the like. The pump casing 44 is made of, for example, a polyester resin, and an O-ring 46 is interposed between a contact portion between the motor casing 12 and the pump casing 44.

A bearing plate 50 made of, for example, stainless steel or Teflon resin is disposed at a position facing the front surface of the impeller 32 at the bottom of the pump casing 44 having a force-up shape. As shown in FIG. 2, a plurality of spiral grooves (spiral groups) 52 having a depth of about 0.01 mm are provided on the surface of the impeller 32 facing the front surface. This constitutes a dynamic pressure bearing 54 in which the impeller 32 is a rotary bearing and the bearing plate 50 is a fixed bearing. In other words, by the rotation of the impeller 32, the handled liquid moves to the inner peripheral side of the spiral groove 52 of the bearing plate 50, and the handled liquid that has lost its place acts to float the impeller 32, It is durable and can support axial loads without contact. In this example, an example is shown in which the bearing plate 50 is attached to the pump casing 44. However, the pump casing and the bearing plate may be integrally formed of the same material.

Thus, a compact dynamic bearing (axial bearing) 54 can be provided at the end of the motor rotor 20 and the bearing structure is simplified. Moreover, the dynamic pressure bearing 54, a type of non-contact bearing, can be expected to have extremely high durability and can also function as a liner, thus reducing the number of parts. Therefore, the pump is designed to be able to rotate at high speeds, while miniaturizing the pump and increasing its efficiency, while extending the service life of the entire pump and improving productivity. Can also be achieved.

In this motor pump, most of the axial load is absorbed by the permanent magnets 30 of the motor rotor 20 and the magnetic attraction of the motor stator 10, but the axial load is reinforced. For this purpose, a dynamic bearing 54 is provided. The motor in this motor pump is a DC brushless motor, and a current is supplied to the motor stator 10 from a power supply lead wire 56, and the motor is driven at a rotation speed of, for example, about 1800 rotations per minute. used.

According to the motor pump of this embodiment, when current is supplied to motor stator 10 from power supply lead wire 56, motor rotor 20 rotates, and suction from suction nozzle 40 of pump casing 44 is performed. The collected liquid is pressurized by an impeller 32 that rotates integrally with the motor rotor 20, and most of the pressure is discharged from the discharge nozzle 42 to the outside of the pump casing 44. A part of the treated liquid passes through the gap between the outer peripheral surface of the motor rotor 20 and the inner peripheral surface of the motor casing 12 after exiting from the impeller 32, and is guided to the radial bearing portion 24, where The sliding surface of the bearing portion 24 is lubricated and cooled, and then returns to the suction portion of the impeller 32 through the communication hole 34 of the shaft portion of the motor rotor 20. At this time, since a pressure lower than the discharge pressure of the impeller 32 acts on the end face of the motor rotor 20 on the side opposite to the impeller, the impeller 32 acting on the motor rotor 20 in the direction of The axial thrust load (axial load) is reduced. Further, a part of the liquid handled flows out of the impeller 32 and is guided to the dynamic pressure bearing 54, and after performing the bearing action as described above, returns to the suction portion of the impeller 32.

FIG. 3 is a diagram illustrating a motor pump according to a second embodiment of the present invention. In the motor pump shown in FIG. 3, one end of, for example, a ceramic rod member 60 is embedded in the inner surface of the motor casing 12 on the side opposite to the opening side so as to extend in the axial direction. The rod member 60 protrudes inward along the axis, and the rod member 60 constitutes a fixed shaft 14. Other configurations are the same as those of the first embodiment. According to the embodiment shown in FIG. 3, since the fixed shaft 14 is made of a ceramic or the like, sufficient strength can be provided as the fixed shaft.

FIG. 4 is a diagram showing a motor pump according to a third embodiment of the present invention. In the motor pump shown in FIG. 4, for example, a fixed shaft made of ceramic and having a detent portion 62a, for example, having a diameter of about 3 mm, is provided between the motor casing 12 and the pump casing 44. 6, and the fixed shaft 62 is passed through a through-hole 64 extending along the axis of the motor rotor 20 to form a radial bearing portion 66. The suction nozzle 40 of the pump casing 44 is located at a position eccentric to the axis 2 by a distance L. On the inner peripheral surface of the through hole 64 of the motor rotor 20, a coating layer 68 is formed by ceramic or Teflon resin coating to ensure durability. Other configurations are the same as those of the first embodiment.

If the suction nozzle 40 of the pump casing 44 is provided on the axis of the fixed shaft 62, it will be difficult to secure the suction passage area, and if the suction passage area is forcibly secured, Undesirable air pockets are created. However, according to this embodiment, such an adverse effect is caused by positioning the suction nozzle 40 of the pump casing 44 at a position eccentric from the axis of the fixed shaft 62 by the distance L. Can be prevented.

And, especially when the fixed shaft 62 is installed horizontally so that the fixed shaft 62 is in the horizontal direction, the shaft center of the suction nozzle 40 provided in the pump casing 44 is closer to the ground than the shaft center of the fixed shaft 62. Be level with the ground at the location. This reduces the flow passage area of the suction portion of the impeller 32 due to the presence of the fixed shaft 62. The amount of air trapped in the suction flow path can be substantially suppressed, and the handled liquid sucked from the suction nozzle 40 is released from the side periphery of the fixed shaft 62 and the impeller 3 It is led to the suction part of 2.

As described above, according to the present invention, it is suitable for use in an area with a very small amount of water and a small output, has excellent durability, has a simple structure, is compact, compact, and has high productivity and high-speed rotation. Designed centrifugal (non-positive displacement) pumps can be provided. Industrial applicability

INDUSTRIAL APPLICABILITY The present invention can be used for a motor pump used in a low output area with a very small amount of water, such as a flow rate range of 1 liter or less per minute to several liters.

Claims

The scope of the claims

1. A cylindrical motor stator,

A motor rotor having a permanent magnet, formed integrally with the impeller, and disposed inside the motor stator;

Pump casing fixed to the open end of the motor casing so as to cover the impeller,

A motor pump comprising a dynamic pressure bearing formed between a front surface of the impeller and a spiral groove provided on an inner surface of a pump casing facing the front surface of the impeller.

2. The motor pump according to claim 1, wherein the spiral groove is provided on a bearing plate fixed to a pump casing.

3. A cylindrical motor stator,

A radial bearing portion is formed between a center hole provided in the shaft center portion of the motor rotor and a fixed shaft fitted into the center hole protruding from the inner surface of the motor casing on the side opposite to the open end. A motor pump characterized by the above-mentioned.

4. The motor pump according to claim 3, wherein the center hole communicates with a communication hole extending from a suction portion of the impeller.

5. A cylindrical motor stator,

A pump casing fixed to an open end of the motor casing so as to cover the impeller;

A pump casing suction port is provided at a position which extends along the axis of the motor stator and is eccentric with respect to the axis of the fixed shaft extending between the motor casing and the pump casing. And a motor pump.

6. When the fixed shaft is installed so as to be horizontal with the ground, it is configured such that the axis of the suction port is located closer to the ground than the axis of the fixed shaft. The motor pump according to claim 5, characterized in that: