JPH0688592A - Canned motor pump - Google Patents

Abstract

PURPOSE:To provide a canned motor pump that is able to reduce an air gap between a magnetic bearing and a displacement sensor and simultaneously to protect each surface of the magnetic bearing and this sensor from abrasion and corrosion. CONSTITUTION:In a canned motor pump provided with an active type magnetic bearing for both radial and axial bearings, sheets 43, 47 and 49 are attached to each surface of those of ring and surface clearance partsin at least one among magnetic poles 31, 32 of the radial magnetic bearing, targets 33, 34 of a radial dispalcement sensor, rotor magnetic poles 39, 40 and stator magnetic poles 36, 37 of the axial magnetic bearing, an axial displacement sensor 41 and its target 42, and then thin films 44, 48 and 50 are formed and coated on each surface of these films 43, 47 and 49 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, an active magnetic bearing has begun to be adopted instead of a slide bearing, in which the bearings can maintain a non-contact state. 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 the canned motor pump using the magnetic bearing, it is still necessary to circulate a part of the liquid for cooling the canned motor, the magnetic bearing and the displacement sensor.

For this reason, the surfaces of the magnetic bearing and the displacement sensor have 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. 6 and 7.

FIG. 6 is a view showing an example in which the radial magnetic bearing is covered with a can. The stator magnetic pole 51 of the radial magnetic bearing is covered with a can 52. Also, the rotating shaft 53
The rotor magnetic pole 54 of the radial magnetic bearing fixed to is also covered by the can 55. An air gap is formed between the magnetic poles 51 and 54, and an annular gap is formed between the cans 52 and 55.

FIG. 7 is a view showing an example in which the axial magnetic bearing is covered by a can, and the stator magnetic poles 56, 57 of the axial magnetic bearing are covered by cans 58, 59, respectively. In addition, the disk 61 fixed to the rotary shaft 53
The rotor magnetic poles 62 and 63 of the axial magnetic bearing are attached to the rotor magnetic poles 62 and 63, and these rotor magnetic poles 62 and 63 are covered by cans 64 and 65, respectively. Air gaps are formed between the magnetic poles 56 and 62 and between the magnetic poles 57 and 63, respectively, and between the cans 58 and 64 and the can 5 respectively.
Planar gaps are formed between 9 and 65, respectively.

[0006]

In the conventional method shown in FIGS. 6 and 7, the liquid always passes through the annular gap and the planar gap at a certain flow rate, and the can alone must withstand abrasion and corrosion. The thickness of the can has to be quite thick because it must be done. The distance of the working surface between the stator pole of the magnetic bearing and the rotor pole of the magnetic bearing by this method,
In addition to the thickness of each can, the so-called air gap needs an annular gap and a planar gap between the cans so that the cans do not come into contact with each other even during rotation. The larger the air gap, the smaller the acting force exerted by the stator poles of the magnetic bearing on the rotor poles of the magnetic bearing. That is, the larger the air gap, the larger the magnetic bearing required. Since the acting force of the magnetic bearing is generally said to decrease in proportion to the square of the air gap, if the air gap doubles, the same acting force will be produced.
A magnetic bearing four times larger is required. Similarly, regarding the displacement sensor, the distance between the displacement sensor and the target of the displacement sensor, that is, the so-called air gap, in addition to the thickness of each can, prevents the cans from coming into contact with each other during rotation. An annular gap and a planar gap between the cans are required for the purpose. The larger the air gap, the lower the output of the displacement sensor with respect to the displacement. The larger this air gap, the larger the displacement sensor and target required.

The present invention has been made in view of the above circumstances, and it is possible to reduce the air gap between the magnetic bearing and the displacement sensor and protect the surfaces of the magnetic bearing and the displacement sensor from wear and corrosion. An object is to provide a canned motor pump.

[0008]

In order to achieve the above-mentioned object, a canned motor pump of the present invention is a canned motor pump using active magnetic bearings for a radial bearing and an axial bearing, and a rotor magnetic pole of the radial magnetic bearing, At least one of the target of the radial displacement sensor, the rotor magnetic pole and the stator magnetic pole of the axial magnetic bearing, the axial displacement sensor and the target thereof is attached with a thin plate on the surface of the annular clearance and the planar clearance, and It is characterized in that a thin film is formed on the surface by thermal spraying and coated.

[0009]

According to the present invention having the above-described structure, the annular gap and the planar gap between the stator magnetic pole of the magnetic bearing and the rotor magnetic pole of the magnetic bearing, and the annular gap and the planar gap between the displacement sensor and the target of the displacement sensor. Since the surface of the is covered with a thin plate and a thin film, these annular gaps and planar gaps are the same as the conventional ones for safety, but it is possible to make the air gap smaller, resulting in a magnetic bearing and a displacement sensor. Can be small. Further, the surfaces of the magnetic bearing and the displacement sensor 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 magnetic bearing can be significantly improved.

[0010]

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 a frame side plate 12 that closes an opening of the frame body 11, and an intermediate cover 13 and an end cover 14 are fixed to the side of the frame body 11 opposite to the impeller.

A stator can 1 is provided at the inner peripheral edge of the frame body 11 on the side opposite to the impeller and the inner peripheral edge of the frame side plate 12.
6 is fixed by welding to form a stator chamber Rs, and the stator magnetic poles 21 and 22 of the radial magnetic bearings, the radial displacement sensors 23 and 24, and the motor stator 25 are housed in the stator chamber Rs. And magnetic pole 2
1, 22, displacement sensors 23, 24 and motor stator 2
5, cylindrical distance pieces 27, 28, 29, 30 are arranged between adjacent members.

On the other hand, on the main shaft 6, rotor magnetic poles 31, 32 of the radial magnetic bearings, radial displacement sensors 23, 23 are provided at positions corresponding to the stator magnetic poles 21, 22 of the radial magnetic bearings.
Targets 33 and 34 of the radial displacement sensor are fixed at positions corresponding to 24, and a motor rotor 35 is fixed at a position corresponding to the motor stator 25.

The intermediate cover 13 and the end cover 14
The stator poles 36 and 37 of the axial magnetic bearing.
Are arranged to face each other. And the stator pole 3
A disc 38 fixed to the main shaft 6 is arranged between 6 and 37, and the magnetic poles 36 and 3 are attached to the disc 38.
The rotor magnetic poles 39, 40 of the axial magnetic bearing are fixed so as to face the magnetic poles 7, respectively.

An axial displacement sensor 41 is arranged on the end cover 14, and a target 42 of the axial displacement sensor is fixed to the axial end of the main shaft 6 so as to face the displacement sensor 41.

Next, the detailed structure of each part of the canned motor pump shown in FIG. 1 will be described with reference to FIGS. FIG. 2 is a diagram showing a detailed structure of the radial magnetic bearing on the impeller side. In FIG. 2, a thin hollow cylindrical shape is formed on the outer peripheral surface of the rotor magnetic pole 31 of the radial magnetic bearing on the impeller side fitted in the yoke. The thin plate 43 is fixed near both ends of the yoke by welding or the like. Then, a thin film 44 is deposited on the entire outer peripheral surface of the thin plate 43 by thermal spraying or the like.
Further, the outer peripheral surface of the rotor magnetic pole 32 of the radial bearing on the side opposite to the impeller has the same structure as that of FIG.

FIG. 3 is a view showing the detailed structure of the radial displacement sensor on the impeller side. In FIG. 3, the target 33 of the radial displacement sensor on the impeller side fitted in the yoke is shown.
A thin hollow cylindrical thin plate 45 is fixed to the outer peripheral surface of the yoke near both ends of the yoke by welding or the like. A thin film 46 is formed on the entire outer peripheral surface of the thin plate 45 by thermal spraying or the like. Since the outer peripheral surface of the target 34 of the radial displacement sensor on the side opposite to the impeller also has the same configuration as that of FIG. 3, detailed drawings are omitted.

FIG. 4 is a diagram showing a detailed structure of the axial magnetic bearing on the side opposite to the impeller. In the axial bearing of FIG. 4, the outer magnetic poles 39, 40 of the axial magnetic bearing fitted in the disk 38 are provided on the outer surfaces thereof. A thin circular disk-shaped thin plate 47 is fixed to the disk 38 by welding or the like. A thin film 48 is formed on the entire surface of the thin plate 47 by thermal spraying or the like. Similarly, with respect to the stator magnetic poles 36 and 37 of the axial magnetic bearing, a thin circular disk-shaped thin plate 47 is welded to the outer surfaces of the stator magnetic poles 36 and 37 of the axial magnetic bearing fitted to the yokes by welding or the like. It is fixed. A thin film 48 is formed on the entire outer surface of the thin plate 47 by thermal spraying or the like.

FIG. 5 is a view showing the detailed structure of the axial displacement sensor on the side opposite to the impeller.
On the outer surface of the target 42 of the axial displacement sensor, a thin annular disc 49 is fixed to the yoke or the like by welding or the like. And the thin plate 49
A thin film 50 is formed on the entire surface of the substrate by thermal spraying or the like.

In the example shown in FIGS. 2 to 5, the rotor magnetic pole of the radial magnetic bearing, the target of the radial displacement sensor,
A structure in which a thin plate much thinner than the conventional can is attached to the surface of the stator magnetic pole and rotor magnetic pole of the axial magnetic bearing, the axial displacement sensor and its target, and the surface of the thin plate is covered with a thin film such as ceramic. It is what By doing so, the air gap can be reduced without changing the annular gap and the planar gap, as compared with the conventional can, and
The wear resistance and corrosion resistance can be remarkably improved.
In this case, attention was paid to a plate material having no pinhole as the thin plate, and as the thin film, attention was paid to the fact that a ceramic or the like having excellent abrasion resistance and corrosion resistance even if the film thickness is thin can be sprayed onto the plate material. For corrosion, a plate material was used, and the plate material 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 from wear, it is necessary to cover the surface of the plate with a film such as ceramics, which has much better wear resistance than the plate. is there. In addition, ceramics and the like have extremely excellent corrosion resistance.

[0020]

As described above, according to the present invention, the annular gap and the surface gap between the stator magnetic pole of the magnetic bearing and the rotor magnetic pole of the magnetic bearing, and the annular gap and the surface between the displacement sensor and the target of the displacement sensor. The air gap can be the same as the conventional one for safety, but the air gap can be made smaller, and as a result, the magnetic bearing and the displacement sensor can be downsized. Further, the surfaces of the magnetic bearing and the displacement sensor 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 magnetic bearing can be significantly 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 magnetic bearing in the canned motor pump according to the present invention.

FIG. 3 is a sectional view showing a detailed structure of a radial displacement sensor in the canned motor pump according to the present invention.

FIG. 4 is a sectional view showing a detailed structure of an axial magnetic bearing in the canned motor pump according to the present invention.

FIG. 5 is a sectional view showing a detailed structure of an axial displacement sensor in the canned motor pump according to the present invention.

FIG. 6 is a sectional view showing a detailed structure of a conventional radial magnetic bearing.

FIG. 7 is a cross-sectional view showing a detailed structure of a conventional axial magnetic bearing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pump casing 5 Impeller 6 Main shaft 10 Motor frame 11 Frame main body 12 Frame side plate 13 Intermediate cover 14 End cover 16 Stator can 21,22 Stator magnetic pole 23,24 Radial displacement sensor 25 Motor stator 31,32 Rotor magnetic pole 33,34 Target 35 Motor rotor 36, 37 Stator magnetic pole 38 Disk 39, 40 Rotor magnetic pole 41 Axial displacement sensor 42 Target 43, 45, 47, 49 Thin plate 44, 46, 48, 50 Thin film

Claims (1)

[Claims] 1. A canned motor pump using active magnetic bearings as radial bearings and axial bearings,
At least one of the rotor magnetic pole of the radial magnetic bearing, the target of the radial displacement sensor, the rotor magnetic pole and the stator magnetic pole of the axial magnetic bearing, and the axial displacement sensor and its target, on the surface of the annular clearance and the planar clearance. A canned motor pump characterized in that a thin plate is attached, and a thin film is formed on the surface of the thin plate by thermal spraying to cover the thin plate.