JPH11324970A - Canned motor pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably support a rotor without contact by storing the stator magnetic poles in a stator chamber with a motor stator, and storing the radial displacement sensors in a radial bearing frame mounted separately from the stator chamber. SOLUTION: The stator magnetic poles 21, 22 of a radial magnetic bearing are stored in a stator chamber Rs with a motor stator 25, and the radial displacement sensors 23, 24 are stored in the radial bearing frames 51 mounted separately from the stator chamber 9 both sides of the stator chamber Rs. Thereby the radial, displacement sensors correctly detect the position of the rotor without hardly affected by the electromagnetic noise from the stator magnetic pole of the radial magnetic bearing and the motor stator, and the noise by the leaked magnetic flux, and further hardly affected by the eddy current generated on the stator can of a motor frame, the temperature of a coil of the stator magnetic pole of the radial magnetic bearing can be normally kept with the proper consumption of the electric current, and the rotor can be stably supported without contact.

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, plain bearings have been used as bearings for canned motor pumps. However, during the operation of the canned motor pump, the shaft sleeve and the thrust plate, which are rotating components, rotate while contacting the bearing on the fixed side, respectively, so that there is a disadvantage that the bearing and the like are worn. In order to overcome this drawback, magnetic bearings have recently been used as bearings for supporting the rotor of a canned motor pump.

FIG. 8 is a sectional view showing a general structure of a canned motor pump equipped with a conventional magnetic bearing. As shown in FIG. 1, a substantially cylindrical container-like 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 flange 3 is formed in the discharge flange 3. A spout 3a is formed. An impeller 5 is housed in the pump casing 1, and the impeller 5 is fixed to and supported by a free end of the main shaft 6. The pump casing 1 is connected to a motor frame 10 via an impeller bracket 7. The motor frame 10 includes a cylindrical frame main body 11 and a frame side plate 12 that closes an opening of the frame main body 11.
The intermediate cover 13 and the end cover 1
4 is fixed.

A stator can 16 is provided on the inner peripheral end of the frame main body 11 on the side opposite to the impeller and the inner peripheral end of the frame side plate 12.
Are fixed by welding to form a stator chamber Rs, in which stator magnetic poles 21, 22 of the radial magnetic bearing, radial displacement sensors 23, 24, and a motor stator 25 are stored. The stator poles 21 and 22, the displacement sensors 23 and 24, and the motor stator 25 are provided with cylindrical distance pieces 27, 28, 29 and 30 between adjacent members. The radial displacement sensors 23, 24 are provided with stator poles 21,
An inductive sensor that is provided adjacent to the sensor 22 and detects displacement of the rotating body by using a change in inductance is used as the displacement sensors 23 and 24.

On the other hand, on the main shaft 6, the rotor magnetic poles 31 and 32 of the radial magnetic bearing, the radial displacement sensor 23 and the radial displacement sensor 23 are located at positions corresponding to the stator magnetic poles 21 and 22 of the radial magnetic bearing.
The targets 33 and 34 of the radial displacement sensor are fixed at positions corresponding to 24, and the motor rotor 35 is fixed at positions corresponding to the motor stator 25.

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

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

The disk 38 mounted on the main shaft 6 is provided in the space defined by the intermediate cover 13 and the end cover 14 so as to face the rotor magnetic poles 39 and 40 of the axial magnetic bearing mounted on the disk 38 and the intermediate cover facing each. The rotor 13 is rotated without contact in the axial direction by the stator magnetic poles 36 and 37 of the axial magnetic bearing attached to the end cover 14 so that the motor rotor 35 is stabilized in the axial direction and is rotatable.

Also, radial touchdown bearings 46 and 47 are provided on the impeller-side bracket 7 and the intermediate cover 13.
Are provided respectively. Axial touchdown bearings 48 and 49 are provided on the intermediate cover 13 and the end cover 14, respectively.

As the radial displacement sensors 23 and 24 and the axial displacement sensor 41, those provided with an electromagnetic shield are also used.

[0011]

However, in a canned motor pump equipped with a conventional magnetic bearing,
The electromagnetic displacement and noise from the stator poles of the radial magnetic bearing and the stator of the canned motor, noise due to leakage magnetic flux, and the effect of eddy current generated in the stator can prevent the radial displacement sensor from detecting the exact rotor position. there were. In other words, it is detected that the position of the rotor detected by the radial displacement sensor is deviated from the center of the shaft more than the actual position of the rotor even though the rotor is not substantially deviated from the center of the shaft. That is the problem. As a result, in the control in the radial direction by the radial magnetic bearing, there is a disadvantage that an excessively large current is consumed more than necessary to generate a suction force for supporting the rotor around the shaft. Further, since an excessively large current flows through the coil of the stator magnetic pole of the radial magnetic bearing, the coil is burned.

In order to prevent the coil from burning, if the stator magnetic poles and the coil of the radial magnetic bearing are made larger so that a large attractive force can be generated even when the current is small, the rotor can be brought into a non-contact state. Although it can be supported near the center of the shaft, it becomes too large to be practical at all. In addition, the electromagnetic displacement and noise from the stator magnetic poles of the radial magnetic bearing and the stator of the canned motor, noise due to leakage magnetic flux, and the effect of eddy current generated in the stator can prevent the radial displacement sensor from accurately detecting the rotor position. The problem remains unresolved.

Also, in the radial displacement sensor provided with the electromagnetic shield, the influence of electromagnetic noise or leakage magnetic flux from the stator magnetic poles of the radial magnetic bearing and the stator of the canned motor and eddy current generated in the stator can is small. Although reduced, they still did not resolve these problems.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a radial displacement sensor is provided with electromagnetic noise from a stator magnetic pole of a radial magnetic bearing and a stator of a canned motor, noise due to leakage magnetic flux, and furthermore, a stator can. The rotor position can be accurately detected without being affected by the generated eddy currents, the current consumption is limited, and the temperature of the coils of the stator poles of the radial magnetic bearing is kept normal. It is an object of the present invention to provide a canned motor pump that can be stably supported.

[0015]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a canned motor in which a radial magnetic bearing, a radial displacement sensor, and a radial touchdown bearing are arranged on both sides of a rotor and a stator of a canned motor, respectively. In the motor pump, the stator magnetic poles of the two radial magnetic bearings are stored in a stator chamber together with the stator of the canned motor, and the radial displacement sensors are stored in radial bearing frames provided separately from the stator chamber on both sides of the stator chamber. It is characterized by having done. Further, the present invention provides a canned motor pump in which a radial magnetic bearing, a radial displacement sensor, and a radial touchdown bearing are arranged on both sides of a rotor and a stator of a canned motor, respectively, wherein the radial displacement sensor includes the radial displacement sensor. An orthogonal displacement sensor is used in which the direction of the magnetic field to be detected is orthogonal to the direction of the magnetic field of the stator magnetic pole of the radial magnetic bearing. Further, the present invention is characterized in that an insulating material is interposed between the radial displacement sensor and the radial magnetic bearing.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS. In the following embodiments, the basic structure of the canned motor pump itself is the same as that of the conventional example shown in FIG.

FIG. 1 is a sectional view showing the structure of the canned motor pump according to the first embodiment of the present invention. As shown in the figure, in this embodiment, the radial bearing frame 50 on the impeller side is disposed between the motor frame 10 and the impeller bracket 7. The radial bearing frame 50 includes a cylindrical frame main body 52 and a frame side plate 54 for closing the opening. A stator can 56 is provided at an inner peripheral end of the frame main body 52 on the impeller side and an inner peripheral end of the frame side plate 54. The radial displacement sensor 23 is fixed inside by welding and is housed therein. On the other hand, the radial bearing frame 51 on the side opposite to the impeller is disposed between the motor frame 10 and the intermediate cover 13. The radial bearing frame 51 includes a cylindrical frame main body 53 and a frame side plate 55 for closing an opening. An inner peripheral end of the frame main body 53 on the side opposite to the impeller and an inner peripheral end of the frame side plate 55 are provided with a stator can 57. Are fixed by welding, and the radial displacement sensor 24 is housed therein. That is, while storing the stator magnetic poles 21 and 22 of the radial magnetic bearing together with the motor stator 25 in the stator chamber Rs,
The radial displacement sensors 23 and 24 are housed in radial bearing frames 51 provided on both sides of the stator chamber Rs separately from the stator chamber Rs.

FIG. 2 is a diagram showing the radial displacement sensors 23 and 24 according to the first embodiment of the present invention.
Is an exploded perspective view, and FIG. 2B is a perspective view. As shown in the figure, the radial displacement sensors 23 and 24 are configured by attaching a coil 233 in a ring shape to a ring-shaped core 231.

In the above configuration, the frame side plates 12, 12a of the motor frame 10 and the radial bearing frame 5
The stator poles 21, 22 of the radial magnetic bearing and the motor stator 25
The effect of noise on the radial displacement sensors 23 and 24 due to electromagnetic noise and magnetic flux leaked from the sensor is considerably reduced. Further, since the stator can 16 of the motor frame 10 and the stator cans 56 and 57 of the radial bearing frames 50 and 51 are separately arranged, eddy current generated in the stator can 16 applied to the radial displacement sensors 23 and 24 is reduced. The effects are each reduced. For this reason, the position of the rotor can be detected quite accurately, and the temperature of the coils of the stator magnetic poles 21 and 22 of the radial magnetic bearing can be kept almost normal, with only appropriate current consumption.

FIG. 3 is a sectional view showing the structure of a canned motor pump according to a second embodiment of the present invention. FIG. 4 shows a radial displacement sensor 23 according to a second embodiment of the present invention.
FIG. 24A is an exploded perspective view, and FIG. 24B is a perspective view. This embodiment is different from the first embodiment in that the radial displacement sensors 23, 2
This is the structure of FIG. That is, this is an embodiment in which the radial displacement sensors 23 and 24 in the first embodiment shown in FIGS. 1 and 2 are replaced with orthogonal displacement sensors. The direction of the magnetic field of each of the stator magnetic poles 21 and 22 of the radial magnetic bearing is the radial direction, whereas the direction of the magnetic field that the orthogonal displacement sensor intends to detect is the axial direction. As described above, by configuring the magnetic field not to be in the same direction but in a right angle direction, electromagnetic noise and noise due to leakage magnetic flux from the stator magnetic poles 21 and 22 of the radial magnetic bearing and the motor stator 25 are reduced by the radial displacement. Sensor 2
It is hard to get into 3,24. Thus, in addition to the effects described with reference to FIG. 1, the effects of electromagnetic noise and noise due to leakage magnetic flux from the stator magnetic poles 21 and 22 of the radial magnetic bearing and the motor stator 25 are further reduced, and a more reliable effect is obtained.

FIG. 5 is a sectional view showing the structure of a canned motor pump according to a third embodiment of the present invention. This embodiment differs from the first embodiment shown in FIG. 1 in that the frame side plate 12 of the motor frame 10, the frame side plate 54 of the radial bearing frame 50 on the impeller side, and the frame side plate 12a of the motor frame 10 are opposite to the frame side plate 12a. The point is that insulating materials 58 and 59 are respectively inserted between the radial bearing frame 51 on the impeller side and the frame side plate 55.

By inserting the insulating materials 58 and 59 in this manner, the frame side plates 12 and 1 of the motor frame 10 are provided.
2a and radial displacement sensors 23 and 24 due to electromagnetic noise and leakage magnetic flux from the stator poles 21 and 22 of the radial magnetic bearing and the motor stator 25, which are transmitted slightly through the contact surfaces of the radial bearing frames 50 and 51 with the frame side plates 54 and 55. The effects of noise on the camera are almost completely eliminated. Further, the frame side plates 12, 12a of the motor frame 10 and the radial bearing frame 5
0, 51 leaks slightly through the contact surfaces with the frame side plates 54, 55, and is given to the radial displacement sensors 23, 24.
The influence of the eddy current from the stator can 16 of the motor frame 10 is almost completely eliminated. Therefore, the electromagnetic noise and the leakage magnetic flux from the stator magnetic poles 21 and 22 of the radial magnetic bearing and the motor stator 25 and the overcurrent from the stator can 16 of the motor frame 10 that affect the radial displacement sensors 23 and 24 are respectively reduced. It is possible to cut off almost completely, to accurately detect the position of the rotor, and to keep the temperature of the coils of the stator magnetic poles 21 and 22 of the radial magnetic bearing normal without consuming an appropriate current.

FIG. 6 is a sectional view showing the structure of a canned motor pump according to a fourth embodiment of the present invention. This embodiment is different from the second embodiment shown in FIG. 3 in that, similarly to the third embodiment of the present invention, the frame side plate 12 of the motor frame 10 and the frame side plate of the radial bearing frame 50 on the impeller side. 54 and motor frame 1
This is the point that insulating materials 58 and 59 are inserted between the frame side plate 12a and the frame side plate 55 of the radial bearing frame 51 on the side opposite to the impeller.

With such a configuration, the radial displacement sensors 23 and 24 are connected to the stator magnetic poles 2 of the radial magnetic bearing in the same manner as the effects described with reference to FIGS.
1, 2 and the motor stator 25, the rotor position can be detected more accurately without being affected by any noise due to the magnetic flux leakage, and the proper current consumption can be suppressed, and the stator magnetic poles 21 of the radial magnetic bearing can be detected. , 22 can be maintained at a normal temperature. Note that this insulating material 5
It is not necessary to constitute the parts 8 and 59 as separate parts, and the same effect can be obtained by coating the corresponding portions of the frame side plates 12, 12a, 54 and 55 with an insulating material by thermal spraying or the like.

FIG. 7 is a sectional view showing the structure of a canned motor pump according to a fifth embodiment of the present invention. This embodiment differs from the conventional canned motor pump shown in FIG. 8 in that the radial displacement sensors 23 and 24 are replaced with orthogonal displacement sensors (having the same structure as that shown in FIG. 4). Even if the radial displacement sensors 23, 24 are stored in the same stator chamber Rs as the motor frame 10, the radial displacement sensors 23, 24 are structurally different from the stator magnetic poles of the radial magnetic bearing as described in the second embodiment. The position of the rotor can be detected to some extent accurately without being largely affected by electromagnetic noise from the motor 21 and the motor stator 25 and noise due to magnetic flux leakage, which is practical.

[0026]

As described in detail above, the present invention has the following excellent effects. Since the stator magnetic poles of the radial magnetic bearing are stored in the stator chamber together with the stator of the canned motor, and the radial displacement sensors are stored in radial bearing frames provided separately from the stator chamber on both sides of the stator chamber. However, there is almost no influence of electromagnetic noise from the stator magnetic poles of the radial magnetic bearing and the motor stator or noise due to leakage magnetic flux, and almost no influence of eddy current generated in the stator can of the motor frame. The position can be detected, the temperature of the coil of the stator magnetic pole of the radial magnetic bearing can be kept normal, and the rotor can be stably supported in a non-contact manner, while consuming only appropriate current.

The use of an orthogonal displacement sensor in which the direction of the magnetic field to be detected by the radial displacement sensor is perpendicular to the direction of the magnetic field of the stator poles of the radial magnetic bearing is used as the radial displacement sensor. Thus, the accurate rotor position can be detected, the appropriate current can be consumed, and the temperature of the coil of the stator magnetic pole of the radial magnetic bearing can be kept normal.

By interposing an insulating material between the radial displacement sensor and the radial magnetic bearing, the above effects can be further improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a structure of a canned motor pump according to a first embodiment of the present invention.

FIGS. 2A and 2B are diagrams showing radial displacement sensors 23 and 24 according to the first embodiment of the present invention, wherein FIG. 2A is an exploded perspective view and FIG. 2B is a perspective view.

FIG. 3 is a sectional view showing a structure of a canned motor pump according to a second embodiment of the present invention.

FIGS. 4A and 4B are diagrams showing radial displacement sensors 23 and 24 according to a second embodiment of the present invention, wherein FIG. 4A is an exploded perspective view and FIG. 4B is a perspective view.

FIG. 5 is a sectional view showing a structure of a canned motor pump according to a third embodiment of the present invention.

FIG. 6 is a sectional view showing a structure of a canned motor pump according to a fourth embodiment of the present invention.

FIG. 7 is a sectional view showing a structure of a canned motor pump according to a fifth embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a general structure of a canned motor pump equipped with a conventional magnetic bearing.

[Explanation of symbols]

 Reference Signs List 1 pump casing 5 impeller 6 main shaft 10 motor frame 11 frame body 12, 12a 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 27, 28, 29, 30 distance Piece 31, 32 Rotor magnetic pole 33, 34 Target 35 Motor rotor 36, 37 Stator magnetic pole 38 Disk 39, 40 Rotor magnetic pole 41 Displacement sensor 42 Target 46, 47, 48, 49 Touchdown bearing 50, 51 Radial bearing frame 52, 53 Frame body 54, 55 Frame side plate 56, 57 Stator can 58, 59 Insulation

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H02K 11/00 H02K 11/00 Q (72) Inventor Nobuhiro Higaki 4-1-1 Motofujisawa, Fujisawa-shi, Kanagawa Prefecture Ebara Corporation Inside

Claims (3)

[Claims] 1. A canned motor pump in which a radial magnetic bearing, a radial displacement sensor, and a radial touchdown bearing are respectively disposed on both sides of a rotor and a stator of a canned motor. The radial displacement sensor is housed in a radial bearing frame provided separately from the stator chamber on both sides of the stator chamber, together with the stator. 2. A canned motor pump in which a radial magnetic bearing, a radial displacement sensor, and a radial touchdown bearing are arranged on both sides of a rotor and a stator of a canned motor, respectively, wherein the radial displacement sensor is provided as the radial displacement sensor. A canned motor pump using an orthogonal displacement sensor in which a direction of a magnetic field to be detected is orthogonal to a direction of a magnetic field of a stator pole of the radial magnetic bearing. 3. The canned motor pump according to claim 1, wherein an insulating material is interposed between the radial displacement sensor and the radial magnetic bearing.