JPH0688591A - Canned motor pump - Google Patents

Abstract

PURPOSE:To provide a canned motor pump that is able to reduce an air gap between a permanent magnet at the rotational side and another one at the fixed side and simultaneously to protect each bearing surface of these permanent magnets from abrasion and corrosion. CONSTITUTION:In a canned motor pump provided with both radial and axial bearings used with a permanent magnet each, four sheets 38, 40, 42 and 44 are attached to, or plated on each surface of these ring and surface clearance parts at least one side of these aforesaid bearings, and then four thin films 39, 41, 43 and 45 are formed and coated on these sheets 38, 40, 42 and 44 or each of their plated surfaces by means of thermal spraying.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a canned motor pump, and more particularly to a canned motor pump having a magnetic bearing for supporting a rotor.

[0002]

2. Description of the Related Art Conventionally, sliding bearings have been used as bearings for canned motor pumps. As the material of the slide bearing, metal is usually used on the rotating side and carbon is used on the stationary side. During operation of the canned motor pump, there has been a drawback that carbon is particularly worn because the rotating side parts rotate while contacting the fixed side parts. In order to overcome this drawback, radial bearings and axial bearings using permanent magnets, which are capable of maintaining non-contact between bearings, have begun to be used in place of slide bearings. In the conventional canned motor pump, a part of the liquid flowing in the pump is usually circulated for the purpose of cooling the canned motor and lubricating the bearing. Even in the case of canned motor pumps that use bearings that use permanent magnets,
Again, it is necessary to circulate some of the liquid to cool the canned motor.

For this reason, the surface of the permanent magnet bearing has to be subjected to some treatment against wear and corrosion in order to come into contact with the circulating liquid. As a processing method thereof, generally, there is a method of welding and covering a metal plate called a can similar to the canned motor. Next, an example of this method will be described with reference to FIGS.

FIG. 4 is a view showing an example in which the radial bearing is covered with a can. The permanent magnet 52 on the rotating side fitted in the yoke 51 is covered with a can 53. The fixed permanent magnet 55 fitted in the yoke 54 is also covered by the can 56. And the permanent magnets 52,
An air gap is formed between the 55 and the cans 53, 5
An annular gap is formed between the six.

FIG. 5 is a view showing an example in which the axial bearing is covered by a can. In the axial bearing, the permanent magnets 58, 59 on the rotating side fitted in the disk 57 are covered by cans 60, 61, respectively. In addition, fixed permanent magnets 62, 6 fitted in the yokes 66, 66.
Similarly, 3 is covered with cans 64 and 65. An air gap is formed between the permanent magnets 58 and 62 and between the permanent magnets 59 and 63, and the cans 60 and 6 are formed.
A planar clearance is formed between the four and the cans 61 and 65, respectively.

[0006]

In the conventional method shown in FIGS. 4 and 5, the liquid always passes through the gaps of the annular gap portion and the gaps of the planar gap portion at a certain flow rate, and only by the can. The can thickness has to be fairly thick as it must withstand wear and corrosion. The distance between the working surfaces of the permanent magnet on the rotating side and the permanent magnet on the fixed side by this method, the so-called air gap, is such that, in addition to the thickness of each can, the cans do not come into contact with each other during rotation. In order to do so, an annular gap and a planar gap between the cans are required. The larger the air gap, the smaller the acting force between the rotating permanent magnet and the stationary permanent magnet. That is, the larger the air gap, the larger the permanent magnet required. Since the acting force of a permanent magnet is generally said to decrease in proportion to the square of the air gap, if the air gap doubles, it will be four times as large as the same acting force. You will need a permanent magnet.

Instead of the can, there is also a process of directly depositing a thin film on the annular clearance surface and the planar clearance surface of the permanent magnet bearing by thermal spraying or the like. There is also a technique generally called a sealing treatment in which only the surface layer is filled. However, even in this sealing treatment, fine pinholes still exist although the number is small. Moreover, in the canned motor pump, since the liquid having a certain flow velocity passes through the surface thereof, there is a risk that the sealing agent on the surface may fall off due to peeling or the like. Therefore, this method cannot completely protect the surface of the permanent magnet from corrosion.

The present invention has been made in view of the above circumstances, and it is possible to reduce the air gap between the permanent magnet on the rotating side and the permanent magnet on the stationary side and to prevent the bearing surface of the permanent magnet from being worn or corroded. An object is to provide a canned motor pump that can be protected.

[0009]

In order to achieve the above-mentioned object, the canned motor pump of the present invention is a canned motor pump provided with a radial bearing and an axial bearing using a permanent magnet, and at least one of the bearings is A thin plate is attached or plated on the surfaces of the annular clearance and the planar clearance, and a thin film is formed on the surface of the thin plate or plating by thermal spraying to cover the surface.

[0010]

According to the present invention having the above-described structure, since the surfaces of the annular clearance and the planar clearance of the radial bearing and the axial bearing are covered with a thin plate, plating, or a thin film, the annular clearance and the planar clearance in the bearing are reduced. The air gap can be made smaller than that of the conventional one, and as a result, the size of the permanent magnet can be reduced. Further, the surface of the permanent magnet bearing can be completely protected from corrosion, the wear resistance and the corrosion resistance can be improved, and the reliability of the canned motor pump using the permanent magnet can be remarkably enhanced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a canned motor pump according to the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, a substantially cylindrical container-shaped pump casing 1 is provided with a suction flange 2 and a discharge flange 3, a suction port 2 a is formed in the suction flange 2, and a discharge port is formed in the discharge flange 3. 3a is formed. An impeller 5 is housed in the pump casing 1, and the impeller 5 has a main shaft 6
Fixed and supported at the free end of. The pump casing 1 is connected to the motor frame 10 via the impeller bracket 7.
It is connected to the. The motor frame 10 is composed of a cylindrical frame body 11 and frame side plates 12a and 12b that close both openings of the frame body 11, and the frame side plate 12b on the side opposite to the impeller has an anti impeller side bracket 13 and an end cover 14. Is fixed.

A stator can 16 is fixed by welding between the inner peripheral ends of the frame side plates 12a and 12b.
The stator chamber Rs is formed, and the motor stator 18 is stored in the stator chamber Rs.

Yokes 20 and 21 are fixed to the impeller-side bracket 7 and the counter-impeller-side bracket 13, respectively, and permanent magnets 22 and 23 on the fixed side of the radial bearing are fitted into the yokes 20 and 21, respectively. Has been. On the other hand, yokes 24 and 25 are fixed to the main shaft 6 at positions corresponding to the yokes 20 and 21, respectively.
Permanent magnets 26 and 27 on the rotating side of the radial bearing are fitted in these yokes 24 and 25, respectively. A motor rotor 28 is fixed to the main shaft 6 at a position corresponding to the motor stator 18.

Further, yokes 30, 31 are fixed to the non-impeller side bracket 13, and the yokes 30, 31 are fixed.
Permanent magnets 32 and 33 on the fixed side of the axial bearing are fitted in 31. A disk 35 fixed to the main shaft 6 is arranged between the permanent magnets 32 and 33, and the permanent magnets 32 and 33 are attached to the disk 35.
The permanent magnets 36, 37 on the rotating side of the axial bearing are fixed so as to face each other.

Next, the detailed structure of each part of the canned motor pump shown in FIG. 1 will be described with reference to FIGS. 2 is a diagram showing a detailed structure of the radial bearing on the impeller side. In FIG. 2, a thin hollow cylindrical thin plate 38 is formed on the outer peripheral surface of the permanent magnet 26 on the rotating side fitted in the yoke 24. It is fixed near both ends of the yoke 24 by welding or the like, or is thinly plated. And
The entire surface of the thin plate 38 or the outer peripheral surface of the plating layer,
A thin film 39 is deposited by thermal spraying or the like. Also the yoke 20
Similarly, with respect to the fixed permanent magnet 22 fitted in the same, a thin hollow cylindrical thin plate 40 is fixed to the inner peripheral surface of the permanent magnet 22 by welding or the like near both ends of the yoke 20, or , Is thinly plated. A thin film 41 is deposited by thermal spraying or the like over the entire inner surface of the thin plate 40 or the plated layer. The radial bearing on the side opposite to the impeller has the same structure as that shown in FIG.

FIG. 3 is a diagram showing the detailed structure of the axial bearing on the side opposite to the impeller. In the axial bearing of FIG. 3, the permanent magnet 3 on the rotating side fitted in the disk 35 is mounted.
On the surface of 6, 37, a thin annular disc thin plate 42 is fixed to the disc 35 by welding or the like, or
It is plated. Then, a thin film 43 is deposited on the entire surface of the thin plate 42 or the plating layer by thermal spraying or the like. Similarly, with respect to the fixed side permanent magnets 32 and 33, a thin annular disc thin plate 44 is welded or the like to the surfaces of the permanent magnets 32 and 33 fitted into the yokes 30 and 31, respectively. It is fixed on or plated. Then, the thin plate 4 or the plating layer is entirely covered with the thin film 4
5 is deposited by thermal spraying or the like.

In the examples shown in FIGS. 2 and 3, first, a plate far thinner than the conventional can is attached to the surface of the permanent magnet of the radial bearing or the permanent magnet of the axial bearing, or thin plating is applied, and further, The thin plate comb has a structure in which the surface of the plating layer is covered with a thin film of ceramic or the like. By doing so, the annular clearance and the planar clearance between the rotating side and the fixed side of the permanent magnet bearing are the same as the conventional one for safety, but the working surface of the rotating side permanent magnet and the fixed side permanent magnet is the same. It is possible to reduce the size of the permanent magnet by further reducing the air gap, which is the distance, and to completely protect the surface of the permanent magnet bearing from abrasion and corrosion. Therefore, first of all, paying attention to the fact that there is a type of plating that does not have pinholes among plate materials that do not have pinholes, and that ceramics that are extremely excellent in wear resistance and corrosion resistance even if the film thickness is thin. We paid attention to the fact that they can be sprayed on the plate material and the plating layer. For corrosion, a plate material or plating was used, and the plate material or plating layer was made as thin as possible to reduce the air gap. However, because it is thin, it is weak against wear, so in order to completely protect the plate or plated layer from wear, a film made of ceramic or the like, which has much better wear resistance than the plate or plated layer, is used. It covers the surface of the plating layer. In addition, ceramics and the like have extremely excellent corrosion resistance.

[0018]

As described above, according to the present invention, it is possible to make the air gap smaller without changing the annular clearance and the planar clearance in the radial bearing and the axial bearing from the conventional one. Therefore, the size of the permanent magnet can be reduced. Further, the surface of the permanent magnet bearing can be completely protected from corrosion, the wear resistance and the corrosion resistance can be improved, and the reliability of the canned motor pump using the permanent magnet can be remarkably improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the overall structure of an embodiment of a canned motor pump according to the present invention.

FIG. 2 is a sectional view showing a detailed structure of a radial bearing in the canned motor pump according to the present invention.

FIG. 3 is a sectional view showing a detailed structure of an axial bearing in the canned motor pump according to the present invention.

FIG. 4 is a sectional view showing a detailed structure of a conventional radial bearing.

FIG. 5 is a cross-sectional view showing a detailed structure of a conventional axial bearing.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Pump casing 5 Impeller 6 Main shaft 7 Impeller side bracket 10 Motor frame 11 Frame main body 12a, 12b Frame side plate 13 Anti-impeller side bracket 16 Stator can 18 Motor stator 20, 21, 24, 25, 30, 31 Yoke 22, 23, 26, 27, 32, 33, 36, 37 Permanent magnet 38, 40, 42, 44 Thin plate or plating layer 39, 41, 43, 45 Thin film

Claims (1)

[Claims] 1. A canned motor pump provided with a radial bearing and an axial bearing using a permanent magnet, and at least one of the bearings is provided with a thin plate or plated on the surfaces of the annular clearance and the planar clearance. A canned motor pump, characterized in that a thin film is formed on the surface of the thin plate or plating by thermal spraying and coated.