JP3035876B2 - Canned motor pump - Google Patents

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. Usually, metal is used on the rotating side and carbon is used on the fixed side as the material of the plain bearing. Thrust generated from a pump or the like is divided into radial thrust and axial thrust according to the direction. The radial thrust is received by the bearing and the shaft sleeve, and the axial thrust is received by the bearing and the thrust plate. However, during operation of the canned motor pump, the shaft sleeve and the thrust plate, which are rotating parts, rotate while contacting the bearing on the fixed side, and thus have a disadvantage that the bearings and the like are worn. Also,
A part of the liquid flowing through the pump is circulated through the canned motor and the bearings for the purpose of lubricating the bearings and cooling the canned motors. Therefore, there is a disadvantage that the purity of the liquid is reduced.

In order to overcome these drawbacks, active magnetic bearings have recently been used as bearings for canned motor pumps. In this method, the position of the rotating body is detected by a displacement sensor that detects displacements in the radial and axial directions, and a magnetic force is applied to the rotating body by an electromagnet according to the amount of the displacement, thereby bringing the rotating body into a non-contact state. To keep. When a magnetic bearing is used, because of non-contact, abrasion unlike a sliding bearing does not occur. Even in the event of a power outage or electrical trouble, even if the rotating body falls down vertically due to its own weight,
A so-called touch-down bearing is provided to prevent the magnetic bearing, the displacement sensor, and the like from coming into contact with another.
Also in this method, for cooling the canned motor, the magnetic bearing and the displacement sensor, and for lubricating the touch-down bearing, respective annular gaps between the canned motor, the radial magnetic bearing and the radial displacement sensor, and the axial magnetic sensor. A part of the liquid flowing in the pump is circulated in the planar gaps between the bearing and the axial displacement sensor. Therefore, it is necessary to reliably protect the liquid contact surfaces of the canned motor, the magnetic bearing, and the displacement sensor from corrosion and wear in order to maintain their functions. As a method,
There is a so-called can cover used for protecting a motor portion of a conventional canned motor pump.

[0004]

However, since the conventional can-covering covers each of them individually, the number of welding points increases, workability is poor, and corrosion and wear are reduced. Has many defects that are considered to be the weakest, so there is a drawback that corrosion and wear are greatly anxious. In addition, for cooling the canned motor, the magnetic bearing and the displacement sensor, and for lubricating the touch-down bearing, the entire amount of the liquid flowing through the respective annular gaps and the planar gaps from the counter impeller side. In general, a system is used in which the pressure is lost in each of the annular gaps and the planar gaps. In addition, a device for reducing pressure loss, such as enlarging a planar gap, is required. However, enlarging the annular gap and the planar gap in this manner has the disadvantage that the magnetic force generated by the magnetic bearing is reduced and the sensitivity of the displacement sensor is also reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has an object to protect a magnetic pole of a radial magnetic bearing, a radial displacement sensor, and a motor stator at a distance from a circulating fluid and to increase a flow path (gap) of the circulating fluid. It is an object of the present invention to provide a canned motor pump capable of surely flowing a circulating fluid without using the same.

[0006]

In order to achieve the above-mentioned object, a canned motor pump according to the present invention comprises a radial magnetic bearing, a radial displacement sensor, and a radial touchdown bearing on both sides of a rotor and a stator of a canned motor. In each of the arranged canned motor pumps, the stator magnetic poles and radial displacement sensors of the radial magnetic bearings on the impeller side and the anti-impeller side are stored in the stator chamber together with the stator of the canned motor, and the stator magnetic poles and radials of these radial magnetic bearings are stored. A distance piece is interposed between adjacent two of the displacement sensor and the stator of the canned motor.

Further, in the canned motor pump of the present invention, the axial magnetic bearing, the axial touchdown bearing, and the axial displacement sensor are arranged on the counter impeller side, and the target and the counter impeller side of the radial displacement sensor on the counter impeller side. A high-pressure liquid is introduced into a space between the radial touch-down bearing and the flow of the liquid is divided into two paths, that is, an impeller side and an anti-impeller side.

[0008]

According to the present invention having the above-described structure, the magnetic poles of the radial magnetic bearing and the radial displacement sensor are stored in the stator chamber together with the stator of the canned motor by providing a distance piece therebetween.
By simply welding both ends of the stator cans, the magnetic poles of the radial magnetic bearing, the radial displacement sensor, and the motor stator can be completely protected from the liquid circulated for cooling them, and , Positioning in the axial direction is simplified. In addition, for cooling the canned motor, the magnetic bearing and the displacement sensor, and for lubricating the touch-down bearing, the circulating liquid is branched into two paths so that each annular gap and each planar gap are formed. Pressure loss, and it is no longer necessary to enlarge each annular gap and each planar gap, so that the magnetic force generated by the magnetic bearing does not decrease, and the sensitivity of the displacement sensor does not decrease. The liquid for cooling the canned motor, the magnetic bearing and the displacement sensor, and the lubrication for the touchdown bearing can be reliably flowed through the respective annular gaps and planar gaps.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the 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-like pump casing 1 is provided with a suction flange 2 and a discharge flange 3. The suction flange 2 has a suction port 2 a and the discharge flange 3 has a discharge port. 3a are formed. An impeller 5 is housed in the pump casing 1, and the impeller 5 is
Is fixed to and supported by the free end of the. The pump casing 1 is connected to the motor frame 10 via the impeller-side bracket 7.
It is connected to the. The motor frame 10 includes 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 frame body 11 on the side opposite to the impeller.

A stator can 1 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.
6 is fixed by welding to form a stator chamber Rs, in which stator magnetic poles 21 and 22 of the radial magnetic bearing, radial displacement sensors 23 and 24, and a motor stator 25 are stored. And magnetic pole 2
1, 22, displacement sensors 23, 24 and motor stator 2
5 is provided with cylindrical distance pieces 27, 28, 29, 30 between adjacent members.

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 disposed between the magnetic poles 36 and 3.
The rotor magnetic poles 39, 40 of the axial magnetic bearing are fixed to face each other.

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

A pipe 43 is provided between the vicinity of the discharge port 3a of the pump casing 1 and the side opposite to the impeller of the frame body 11, and high-pressure liquid discharged from the pump passes through the pipe 43 and the orifice a. It is supplied to the inside of the rotor chamber Rr. A pipe 44 is provided between the end cover 14 and the vicinity of the suction port 2a of the pump casing 1, and the high-pressure liquid supplied from the pipe 43 passes through an axial magnetic bearing to the orifice b and the pipe 44.
And is configured to return to the suction port 2a via the.

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

Thus, according to the present embodiment, the magnetic poles 21 and 22 of the radial magnetic bearing and the radial displacement sensor 23,
24 and a motor stator 25, and distance pieces 27, 28, 29 and 30 are provided between the motor stator 25 and the motor stator 25, and stored in a stator chamber _RS . For this reason, only by welding both ends of one stator can 16, the magnetic poles 21 and 22 of the radial magnetic bearing and the radial displacement sensor 23,
24 and the motor stator 25 can be completely protected from the liquid circulated for cooling them, and the number of welding points can be reduced. Further, by providing each of the distance pieces 27 to 30, positioning of the magnetic poles 21 and 22 of the radial magnetic bearing, the radial displacement sensors 23 and 24, and the motor stator 25 in the axial direction is simplified. Further, a high pressure is applied to the space between the target 34 of the radial displacement sensor 24 on the counter impeller side and the radial touchdown bearing 47 on the counter impeller side via the high pressure side pipe 43 from the vicinity of the pump discharge port 3a. Liquid, and branch from it into two paths, the impeller side and the anti-impeller side, so that the magnetic force generated by the magnetic bearing does not decrease and the sensitivity of the displacement sensor is improved. Without lowering, the liquid can flow through the annular gap and the planar gap for cooling the canned motor, the magnetic bearing and the displacement sensor, and for lubricating the touchdown bearing.

Here, the radial displacement sensor 2 on the side opposite to the impeller from the discharge section of the pump via the pipe 43 on the high pressure side.
4 shows that the high-pressure liquid is introduced into the space between the target 34 and the radial touch-down bearing 47 on the non-impeller side, and branches into two paths, that is, the impeller side and the non-impeller side. In order to explain the above, let's look at the magnitude relation of the pressure of each part. P1 is the discharge pressure of the pump, which is higher than any other pressure. P7 is the pump suction pressure, which is lower than any other pressure. P2 is smaller than P1 by the pressure loss of the orifice part a. P3 is smaller than P2 because of the pressure loss in the annular gap between the radial displacement sensor and the radial magnetic bearing on the side opposite to the impeller. P4 is smaller than P3 due to the pressure loss of the motor rotor 35. P5 is
It is smaller than P4 due to the pressure loss in the annular gap between the radial displacement sensor and the radial magnetic bearing on the impeller side. P6
Is smaller than P5 due to the pressure loss of the radial touchdown bearing 46 on the impeller side. P6 is substantially equal to P7 because the impeller 5 has the balance hole 5a. P8
Is smaller than P2 due to the pressure loss of the radial touchdown bearing 47 on the anti-impeller side. P9 communicates with the suction part of the pump through the low pressure side pipe 44, but the orifice part b
Is slightly higher than P7 because of the aperture.

From the pressure relationship described above, P1>P2> P
3>P4>P5>P6> P7, and P2>P8>P9>
At P7, the liquid that has passed through the high-pressure pipe 43 enters the space between the target 34 of the radial displacement sensor 24 on the counter impeller side and the radial touchdown bearing 47 on the counter impeller side, and , And branches into two paths: an impeller side, which is the second path, and an anti-impeller side, which is the second path. Therefore, for cooling the canned motor, magnetic bearing and displacement sensor,
In the first route, the liquid for lubricating the touchdown bearing is used for cooling the canned motor, the radial magnetic bearing and the radial displacement sensor, and for lubricating the radial touchdown bearing on the impeller side. The second path is used for cooling the axial magnetic bearing and the axial displacement sensor, and for lubricating the radial touchdown bearing on the side opposite to the impeller. Therefore, in order to cool the canned motor, the magnetic bearing and the displacement sensor, and to lubricate the touch-down bearing, the whole amount is put in from the counter impeller side and flows in one direction to the suction port side of the pump. In comparison, since the required total amount can be divided into two paths, the amount to one path is reduced, and the pressure loss of each annular gap and each planar gap is proportional to the square of the amount. Therefore, the object can be achieved much more efficiently without increasing the annular gap and the planar gap.
Next, look at axial thrust. From the pressure relationship in the first path, the sum of axial thrusts acting on the motor rotor 35, the rotor magnetic poles 31 and 32 of the radial magnetic bearing, the targets 33 and 34 of the radial displacement sensor, and the P6 portion on the impeller side is T1. T1 acts in the direction of the impeller. In the second path, the axial thrust acting on the disk 38 including the rotor magnetic poles 39 and 40 of the axial magnetic bearing is defined as T2. T2 acts in the direction opposite to the impeller. Therefore, T2 also has the advantage that axial thrust can be reduced because it acts to offset T1.

[0019]

As described above, according to the present invention,
By simply welding both ends of one stator can, the magnetic poles of the radial magnetic bearing, the radial displacement sensor, and the motor stator can be completely protected from the liquid circulated for cooling them, and The mutual positioning in the axial direction has been simplified.

Further, according to the present invention, the liquid circulating for cooling the canned motor, the magnetic bearing and the displacement sensor, and for lubricating the touch-down bearing are branched into two paths so that each annular gap and Since the pressure loss in each planar gap can be reduced, and it is no longer necessary to increase each annular clearance and each planar clearance, the magnetic force generated by the magnetic bearing does not decrease and the sensitivity of the displacement sensor also increases. Without lowering, the liquid for cooling the canned motor and the magnetic bearing and displacement sensor, and for lubricating the touchdown bearing,
It is possible to reliably flow into each annular gap and each planar gap.

[Brief description of the drawings]

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

[Explanation of symbols]

 Reference Signs List 1 pump casing 5 impeller 6 main shaft 10 motor frame 11 frame 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 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 43, 44 piping 46, 47, 48, 49 touchdown bearing

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-59-138797 (JP, A) JP-A-2-97713 (JP, A) JP-B-44-5729 (JP, B1) (58) Field (Int.Cl. ⁷ , DB name) F04D 13/06 F04D 29/04

Claims (2)

(57) [Claims] 1. 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. The stator magnetic pole of the bearing and the radial displacement sensor are stored in the stator chamber together with the stator of the canned motor, and a distance piece is placed at a location where any two of the stator magnetic pole of the radial magnetic bearing, the radial displacement sensor and the stator of the canned motor are adjacent. A canned motor pump that is interposed. 2. An axial magnetic bearing, an axial touch-down bearing, and an axial displacement sensor are disposed on the counter impeller side, and a target of the radial displacement sensor on the counter impeller side and a radial touch-down bearing on the counter impeller side. 2. A high-pressure liquid is introduced into the space between the two, and the flow of the liquid is branched into two paths, that is, an impeller side and an anti-impeller side.
The canned motor pump as described.