JP4081566B2 - Canned motor pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a canned motor pump, and more particularly to a canned motor pump including a bearing wear detector that can easily monitor the progress of radial and axial bearing wear using an electrical detection method. .
[0002]
[Prior art]
FIG. 11 is a cross-sectional view showing a general configuration of this type of canned motor pump. As shown in FIG. 11, the canned motor pump includes a pump part P and a motor part M. An impeller 2 is disposed inside the pump casing 1 of the pump portion P, and a casing cover 3 is fixed to an opening on the high pressure side of the pump casing 1. Further, the casing cover 3 is formed with a flow hole 4 for guiding a part of the pump-treated liquid whose pressure has been increased after passing through the impeller 2.
[0003]
One end of the rotor 5 is inserted into the casing cover 3, and a distance piece (sleeve) 6, a thrust plate 7 a, a shaft sleeve 8 a and an impeller 2 fitted to the rotor 5 are bolted to one end of the rotor 5. 22 is fixed. A thrust plate 7 b and a shaft sleeve 8 b are fixed to the other end of the rotor 5 by bolts 23.
[0004]
The rotor 5 is rotatably supported at both ends thereof via a pair of bearings 9a and 9b, and the rotor 10 of the motor part M is fixed substantially at the center thereof, and the bearing 9a is attached to the casing cover 3 at the end. Bearings 9b are mounted on the cover 11, respectively. Further, a through hole 14 penetrating in the axial direction is formed inside the rotor 5, and the through hole 14 penetrates the bolts 22 and 23 at both ends and opens on both sides.
[0005]
The stator 13 of the motor unit M is fitted to a motor frame 24, and frame side plates 25a and 25b are fitted to both ends of the motor frame 24. Further, the can 12a of the rotor 10 of the motor unit M and the can 12b of the stator 13 of the motor unit M protect the rotor 10 and the stator 13 from touching the pump-handed liquid, respectively. Further, two sets of inductive sensors S1 and S3, S2 and S4 are disposed on both end faces of the iron core of the stator 13.
[0006]
In the conventional canned motor pump, since the shaft sleeves 8a and 8b and the thrust plates 7a and 7b on the rotating side rotate while in contact with the bearings 9a and 9b on the fixed side during operation, The carbon bearings 9a and 9b are mainly worn, and the amount of wear increases with the operation time. As the wear amount of the bearings 9a and 9b increases with the operating time, the runout of the rotor 5 increases, and when the wear further proceeds, the can 12a of the rotor 10 and the can 12b of the stator 13 come into contact with each other. It will be damaged and will continue to be damaged. If the can 12b of the stator 13 is damaged, the pump handling liquid enters the stator 13 and causes the winding of the stator 13 to deteriorate, resulting in a fatal failure of the can motor body.
[0007]
In addition, since the canned motor pump has an integrated pressure vessel structure that does not have a shaft seal portion between the pump portion P and the motor portion M, it is impossible to visually observe the swing of the rotor 5 from the outside of the main body. Therefore, even if the bearings 9a and 9b are worn due to some cause such as long-term use or contamination of foreign matter, the change cannot be confirmed from the outside. Therefore, various detection means for detecting the wear state of the bearings 9a and 9b have been proposed.
[0008]
Among the detection means for detecting the wear state of the bearing that has been carried out so far, as the electrical detection means, as shown in FIG. 11 and FIG. 12 (a), two sets of both ends of the iron core of the stator 13 are provided. Inductive sensors S1 and S3, S2 and S4 are provided, and as shown in FIG. 12B, the inductive sensors S1 and S3 are arranged 180 degrees symmetrically. Similarly, the inductive sensors S2 and S4 are also 180 degrees symmetrical. There is a detection means having a configuration arranged in the above.
[0009]
This detecting means detects wear in the radial direction (radial direction A) of the bearings 9a and 9b by the induction type sensors S1 and S3, and S2 and S4, and wear in the axial direction (axial direction B) is detected by the induction type sensor S1. Detection is performed in S2, or S3 and S4. That is, the wear of the bearing in the radial direction A is caused by the difference between the induced voltages of the induction sensors S1 and S3 (differential output) and the difference between the induced voltages of the induction sensors S2 and S4 (differential output). This is done by detecting and displaying the larger one on a detector (not shown). Further, the wear of the bearing in the axial direction B is caused by the difference between the induced voltages of the induction sensors S1 and S2 (differential output) or the difference between the induced voltages of the induction sensors S3 and S4 (differential output). This is done by detecting.
[0010]
FIG. 13 shows an example of a processing circuit for signals output from the inductive sensors S1, S2, S3, S4. The configuration of this signal processing circuit includes input circuits 31 to 34 that receive the signals of the inductive sensors S1, S2, S3, and S4, differential amplifiers 35 to 38 for comparison, and offset adjustment circuits 39 to 42 after comparison. The determination circuit 43 calculates the position of the rotor 5 from each signal processing result, and the display circuit 44 displays the determination result. Accordingly, the outputs of the inductive sensors S1, S2, S3, and S4 are input to a comparison circuit unit for discriminating each output signal, and the rotor is determined by the outputs from the inductive sensors S1, S2, S3, and S4. The position of 5 is detected, and the wear state of the bearing is determined from the change in the position.
[0011]
FIG. 14 shows the principle of detecting the wear of the bearing in the radial direction A. As shown in FIG. 14, when the bearing is worn mainly in the upward direction, the rotor 5 moves upward, so that the upper gap δ1 in the radial direction is smaller than the lower gap δ2. The closer the rotor 10 is to the magnetic poles of the induction sensors S1, S2, S3, S4, the greater the induced voltage of each sensor. Therefore, the magnitude relationship between the induced voltages induced in each of the inductive sensors S1, S2, S3, S4 is
S1> S3 and S2> S4
It becomes. In addition, the magnitude relationship of the difference (differential voltage) in induced voltage induced in each of the inductive sensors S1 and S3 and S2 and S4 is
(S1-S3) <(S2-S4)
Thus, by displaying the differential output of (S2-S4) on the detector through a circuit, it is possible to detect the larger wear in the radial direction A of the bearing.
[0012]
FIG. 15 shows the principle of detecting the wear of the bearing in the axial direction B. When the end face of the bearing 9a on the impeller 2 side is worn, the rotor 5 moves in the direction of the impeller 2 as shown in FIG. 15, so that the magnetic poles of the induction sensors S1, S2, S3, S4 rotate. The size relationship of the overlapping lengths L1, L2, L3, and L4 along the axial direction with the outer peripheral surface of the end portion of the child 10 is as follows.
L1> L2 and L3> L4
The magnitude relationship of the induced voltages induced in each of the induction sensors S1, S2, S3, S4 is
S1> S2 and S3> S4
It becomes. Therefore,
(S1-S2) or (S3-S4)
The wear in the axial direction B of the bearing can be detected by comparing the differential outputs of the two by the circuit and displaying the larger one on the detector via the circuit.
[0013]
FIG. 16A shows the differential output with respect to the wear amount of the bearing in the radial direction A. FIG. Conventional example 1 in the figure shows a case where the load current of the motor is large or the operation point of the pump is considerably smaller than the maximum efficiency point, and conventional example 2 shows a case where the load current of the motor is small or the operation point of the pump is low. The case near the maximum efficiency point is shown. FIG. 16B shows the differential output with respect to the wear amount of the bearing in the axial direction B. FIG. Similarly to the radial direction A, Conventional Example 1 in the figure shows a case where the load current of the motor is large, and Conventional Example 2 shows a case where the load current of the motor is small.
[0014]
In either case, the differential output fluctuates due to changes in the load current of the motor or the operating point of the pump. In addition, as will be described later, the number of grooves Z of the motor rotor 10 due to the difference between the power supply frequency of the canned motor and the actual operating frequency, or the number Z of grooves of the motor rotor 10 due to the installation error of the induction type sensor, and the rotational frequency N2 of the canned motor pump There is another problem that the differential output of the sensor is also affected by the groove harmonic component that is the product of (Z × N2).
[0015]
As another electrical detection means, the wear state of the bearing is detected by using a winding having a search coil in the winding slot of the stator 13 or a canned motor having a special winding structure. There are detection means and the like.
[0016]
However, in this electrical detection means, the differential output of the sensor is also affected by changes in the load current of the motor, the operating point of the pump, and the groove harmonic components due to the aforementioned swell and inductive sensor mounting errors. There is a problem in that the wear state of the bearing is not accurately displayed.
[0017]
On the other hand, as an example of the mechanical detection means, a mechanical contact portion that is fixed to the end cover 11 at a constant distance from the rotor 5 at the shaft end on the side opposite to the impeller of the rotor 5, and this contact portion is a rotating body. There is a detection means having a function of exhausting gas enclosed inside by contact wear with the outside. In the case of such a detection means, the wear in the radial direction A of the bearing 9b on the anti-impeller side can be detected, but the wear in the radial direction A of the bearing 9a on the impeller 2 side can hardly be detected. Since the gas enclosed inside is released after the detection means is activated, it is necessary to replace the detection means itself together with the worn bearing, and there is a problem that the number of maintenance parts is inevitably increased.
[0018]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described circumstances. In a canned motor pump in which an impeller is fixed to one end of a rotor and the rotor is supported by bearings disposed on both sides of the impeller side and the opposite impeller side, It is an object of the present invention to provide a canned motor pump that can easily detect the progress of wear of bearings in the axial direction and the axial direction using an electrical detection method.
[0019]
[Means for Solving the Problems]
The invention according to claim 1 is a canned motor pump in which an impeller is fixed to one end of a rotor, and the rotor is supported by bearings arranged on both sides of the impeller side and the anti-impeller side. A notch is provided in a part of the end surface of the notch, and the notch And an iron core and a detection coil wound around the iron core, and the iron core around which the detection coil is wound extends toward the outer peripheral side of the stator in the radial direction and is bent and fixed in a U-shape. Heading toward the inner periphery of the rotor, it has a shield that absorbs the magnetic flux formed by the load current of the rotor A low-pass filter circuit in which a plurality of inductive sensors are arranged so that the detection surface of the sensor overlaps at least a part of the outer peripheral surface of the end of the rotor core along the axial direction and attenuates frequency components of several tens of Hz or more And the wear state of the bearing is monitored by detecting the position of the rotor from the output of the inductive sensor that has passed through a high-pass filter circuit that attenuates a frequency component of several Hz or less. It is a motor pump.
[0020]
As a result, the groove harmonic component and the undulation frequency component of the canned motor included in the output of each inductive sensor are attenuated, so that the output of the rotor is not affected by these effects and the rotor output is influenced by the respective outputs from the inductive sensor. The position is detected, and the wear state of the bearing can be determined from the change in the position.
[0021]
The invention according to claim 2 is characterized in that the inductive sensor is arranged such that the detection surface of the inductive sensor overlaps with the outer peripheral surface of the end of the rotor core about half along the axial direction. The canned motor pump according to claim 1. As a result, when the rotor is moved in the axial direction by the distance La due to wear of the end face of the bearing, a differential output corresponding to 2 × La, which is twice this distance, can be obtained.
[0022]
According to a third aspect of the present invention, the inductive sensor is arranged such that a detection surface of the inductive sensor overlaps with the outer peripheral surface of the end of the rotor core substantially along the entire axial direction. The canned motor pump according to claim 1. This is effective for a canned motor pump in which the magnetic flux at the end of the magnetic flux passing through the gap between the stator and the rotor formed by the stator windings is relatively large.
[0023]
The invention according to claim 4 is the canned motor pump according to any one of claims 1 to 3, further comprising a circuit that outputs only the maximum value of the output of the inductive sensor. As a result, a stable differential output can be obtained, the shake of the detector needle can be eliminated, and the wear state of the bearing can be accurately detected.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 4 show a canned motor pump according to a first embodiment of the present invention. The same or corresponding parts as those in the conventional example shown in FIGS. 11 to 13 are denoted by the same reference numerals. The duplicate description is omitted.
[0025]
That is, as shown in FIGS. 1 and 2 (a), the canned motor pump includes two sets of induction sensors S1 and S3, S2 and S4 having shielding structures on both end surfaces of the iron core of the stator 13. Is provided. As shown in FIG. 2B, the inductive sensors S1 and S3 are arranged symmetrically by 180 °, and similarly, the inductive sensors S2 and S4 are arranged symmetrically by 180 °. Thereby, the wear in the radial direction (radial direction A) of the bearings 9a and 9b is caused by the difference between the induced voltages of the inductive sensors S1 and S3 (differential output) and the induced voltages of the inductive sensors S2 and S4. Is detected by detecting the difference between the two (differential output) and the larger one is displayed on a detector (not shown), and wear in the axial direction (axial direction B) of the bearings 9a and 9b is induced. This is performed by detecting the difference between the induced voltages of the type sensors S1 and S2 (differential output) or the difference between the induced voltages of the induction type sensors S3 and S4 (differential output).
[0026]
FIG. 3 is a detailed view of a mounting portion of the inductive sensor S1 having a shielding structure, and the other inductive sensors S2, S3, and S4 have the same configuration. In FIG. 3, the inductive sensor S1 includes an iron core S1a and a detection coil S1b wound around the iron core S1a. The iron core S1a around which the detection coil S1b is wound further includes an outer periphery of the stator 13 in the radial direction. It has a shielding portion S1d that extends toward the side, bends in a U-shape, and again toward the inner peripheral side of the stator. Thereby, the part around which the detection coil S1b of the iron core S1a is wound is shielded by the shielding part S1d. The detection surface S1c of the iron core S1a around which the detection coil S1b is wound is disposed on substantially the same surface as the inner peripheral surface 13a of the stator 13. Inductive sensor S1 is arranged such that its detection surface S1c overlaps the outer peripheral surface of the end of the iron core of rotor 10 by a length L1o along the axial direction. This length L1o is about half of the entire length of the detection surface S1c of the inductive sensor S1. The inductive sensor S1 is disposed in the notch 13b on the end face of the stator 13.
[0027]
As shown in FIG. 2A, in the induction type sensors S2, S3, and S4, the end portions of the iron core of the rotor 10 are approximately L2o, L3o, and L4o that are about half the entire length of the detection surface. It arrange | positions so that it may overlap with an outer peripheral surface along an axial direction.
[0028]
With this configuration, the magnetic flux ΦR formed mainly by the load current of the end ring 10a of the rotor 10 is absorbed by the shielding portion S1d of the iron core S1a, and thereby the detection coil S1b is wound. The magnetic flux ΦR hardly enters the detection surface S1c in the vicinity. On the other hand, the magnetic flux ΦL at the end of the magnetic flux ΦS passing through the gap between the stator 13 and the rotor 10 formed by the winding of the stator 13 is formed so as to pass through the detection surface S1c of the inductive sensor S1. The amount of magnetic flux can be detected by the detection coil S1b. Therefore, the inductive sensor S1 is hardly affected by the magnetic flux ΦR formed mainly by the load current of the end ring 10a of the rotor 10, and is at the end of the magnetic flux ΦS passing through the gap between the stator 13 and the rotor 10. It becomes possible to detect the magnetic flux ΦL.
[0029]
Here, the magnetic flux ΦL at the end of the magnetic flux ΦS passing through the gap between the stator 13 and the rotor 10 formed by the winding of the stator 13 is the frequency of the power source of the canned motor pump (hereinafter referred to as the power supply frequency N0). On the other hand, the induced voltage detected by the detection coil S1b of the inductive sensor S1 has a component of the canned motor slip frequency (hereinafter referred to as slip frequency N1). According to experiments, the slip frequency N1 is several Hz or less, and increases as the load on the canned motor increases. Therefore, it is consistent with a generally known motor slip rate. For this reason, the frequency (henceforth the rotation frequency N2) which is rotating the actual canned motor pump is as follows.
(Rotation frequency N2) = (Power supply frequency N0) − (Slip frequency N1)
[0030]
The slip frequency N1 is a frequency determined by the load factor of the canned motor, and when there is no load at all,
(Slip frequency N1) = 0
It becomes. In the normal use range of the canned motor,
0 <(slip frequency N1) <(several Hz)
You can think of it.
[0031]
Due to this slip frequency N1, not only in the case of a worn bearing but also in the case of a bearing that is not normally worn, the regular gap (diameter gap in the radial direction A and end play in the axial direction B) is generated. It affects the needle of the detector (not shown). In other words, the differential output of the sensor has periodic fluctuations (hereinafter referred to as waviness) having a component of slip frequency N1 (several Hz or less), and the detector needle is normal even in a normal non-wearing bearing. Periodically reciprocates between a normal position and a somewhat worn position. Therefore, even in a bearing that is not normally worn, the detector needle swings as if it is worn to some extent.
[0032]
On the other hand, the differential output of the sensor is also affected by the groove harmonic component which is the product of the number of grooves Z of the rotor 10 and the rotational frequency N2 of the canned motor pump (Z × N2). Since the inductive sensors S1 and S3 are arranged 180 degrees symmetrically and the inductive sensors S2 and S4 are also arranged 180 degrees symmetrically, theoretically, for example, the bearings are completely worn by each pair of sensors. If not, the differential outputs will cancel each other, and if they are worn out, the differential outputs will increase. Here, since the number of grooves Z of the rotor 10 is generally about 20 to 30, the groove harmonic component has a very high frequency. That is, if the inductive sensor is not correctly mounted, the phase will shift, and even a slight phase shift will detect a component that is not originally a component due to wear of the bearing as a differential output.
[0033]
For this reason, in this embodiment, a low pass filter for attenuating groove harmonic components of several tens of Hz or more and a high pass filter for attenuating undulation components of several Hz or less are provided in the circuit.
[0034]
FIG. 4 shows a processing circuit for signals output from the inductive sensors S1, S2, S3, S4. The signal processing circuit includes input circuits 31 to 34 that receive signals from the inductive sensors S1, S2, S3, and S4, low-pass filter circuits 45 to 48 that attenuate groove harmonic components, and a differential amplifier for comparison. 35 to 38, high-pass filter circuits 49 to 52 for attenuating the swell component, offset adjustment circuits 39 to 42 after comparison, determination circuit 43 for calculating the rotor position from the respective signal processing results, and the determination result are displayed. The display circuit 44 is configured.
[0035]
Here, as shown in FIG. 5, the low-pass filter circuits 45 to 48 attenuate a frequency component of, for example, 70 Hz or more, and the high-pass filter circuits 49 to 52 attenuate, for example, a frequency component of 10 Hz or less. is there.
[0036]
As a result, the output of each inductive sensor S1, S2, S3, S4 passes through the low-pass filter circuits 45 to 48, the groove harmonic component is attenuated, and is input to the comparison circuit section for discriminating each output signal. Further, the swell component is attenuated through the high-pass filter circuits 49 to 52. Therefore, it is possible to detect the position of the rotor 5 based on the outputs of the induction sensors S1, S2, S3, and S4 and determine the wear state of the bearing from the change in the position.
[0037]
FIG. 6 shows the principle of detection of bearing wear in the radial direction A. As shown in FIG. 6, when the bearing is worn mainly in the upward direction, the rotor 5 moves upward, so that the upper gap δ1 in the radial direction is smaller than the lower gap δ2. The closer the rotor 10 is to the magnetic poles of the induction sensors S1, S2, S3, S4, the greater the induced voltage of each sensor. Therefore, the magnitude relationship between the induced voltages induced in each of the inductive sensors S1, S2, S3, S4 is
S1> S3 and S2> S4
It becomes. In addition, the magnitude relationship of the difference (differential voltage) in induced voltage induced in each of the inductive sensors S1 and S3 and S2 and S4 is
(S1-S3) <(S2-S4)
Thus, by displaying the differential output of (S2-S4) on the detector through a circuit, it is possible to detect the larger wear in the radial direction A of the bearing.
[0038]
FIG. 7 shows the principle of detecting the wear of the bearing in the axial direction B. Regarding the axial direction B, the overlapping lengths L1o, L2o, L3o, and L4o in the axial direction of the magnetic poles of the induction sensors S1, S2, S3, and S4 with the rotor 10 are located almost half of the magnetic poles. The differential output (S1-S2) or (S3-S4) has a greater change in the overlap length in the axial direction with respect to the movement amount in the axial direction B. That is, when the end face of the bearing 9a on the impeller 2 side is worn by the distance La and the rotor 5 moves by the distance La in the direction of the impeller 2, as shown in FIG. 7, the axial direction of the magnetic pole of the induction sensor S1 The overlapping length L1 with the rotor 10 and the overlapping length L2 with the rotor 10 in the axial direction of the magnetic poles of the induction type sensor S2 change as follows.
L1 = L1o + La, L2 = L2o−La
In the state where there is no wear of the bearing,
L1o = L2o
Therefore, the difference in overlap length between the inductive sensors S1 and S2 is
L1-L2 = 2 × La
It becomes.
[0039]
Accordingly, since the axial overlap lengths L1 and L2 of the magnetic poles of the induction type sensors S1 and S2 with the rotor 10 may be considered to be proportional to the induced voltage of the sensor, the differential output (S1-S2) is the original movement. Double the amount. As for the inductive sensors S3 and S4, the differential output is twice the original moving amount, as in the inductive sensors S1 and S2.
[0040]
FIG. 8 shows a mounting portion of the induction type sensor of the canned motor pump according to the second embodiment of the present invention, which extends the induction type sensors S1 and S2 over the entire lengths L1a and L2a of their detection surfaces. The rotor 10 is disposed so as to overlap the outer peripheral surface of the end of the iron core along the axial direction. Although not shown, the inductive sensors S3 and S4 are similarly arranged.
[0041]
In this embodiment, as described above, when the rotor 5 moves in the direction of the impeller 2 by the distance La, the overlapping length L1b with the rotor 10 in the axial direction of the magnetic pole of the induction sensor S1 and the induction The overlapping length L2b with the rotor 10 in the axial direction of the magnetic pole of the mold sensor S2 changes as follows.
L1b = L1a, L2b = L2a-La
In the state where there is no wear of the bearing,
L1a = L2a
Therefore, the difference in overlap length between the inductive sensors S1 and S2 is
L1b-L2b = La
It becomes.
[0042]
Therefore, the differential output (S1-S2) in the axial direction B itself is the same as the original movement amount, but is effective for a canned motor pump having a relatively large magnetic flux density ΦL.
[0043]
By configuring as described above, the wear state of the bearing can be judged almost without being affected by the groove harmonic component and the swell frequency component of the canned motor. Since the sensor rotates at a frequency different from N2 (hereinafter referred to as revolution), the differential output of the sensor fluctuates periodically. This differential output does not change irregularly, but stably and periodically repeats between a certain maximum value and a certain minimum value, as shown in FIGS. 9 (a) and 9 (b). In other words, at least the maximum value of the differential output does not change even by revolution, whereby the wear of the bearing can be accurately detected.
[0044]
FIG. 10 shows a signal processing circuit of a canned motor pump according to a third embodiment of the present invention, which includes means for eliminating the differential output fluctuation of the canned motor. The signal processing circuit includes input circuits 31 to 34 that receive signals from the inductive sensors S1, S2, S3, and S4, low-pass filter circuits 45 to 48 that attenuate groove harmonic components, and a differential amplifier for comparison. 35 to 38, high-pass filter circuits 49 to 52 for attenuating the swell component, offset adjustment circuits 39 to 42 after comparison, determination circuit 43 for calculating the rotor position from each signal processing result, maximum value of the determination result A peak hold circuit 53 for taking out only the signal, and a display circuit 44 for displaying only the maximum value.
[0045]
As a result, the output of each inductive sensor S1, S2, S3, S4 passes through the low-pass filter circuits 45 to 48, the groove harmonic component is attenuated, and is input to the comparison circuit section for discriminating each output signal. Then, the swell component is attenuated through the high-pass filter circuits 49 to 52. Further, only the maximum value of the differential output is detected by the peak hold circuit 53. Therefore, it is possible to detect the position of the rotor 5 based on the outputs of the induction sensors S1, S2, S3, and S4 and determine the wear state of the bearing from the change in the position.
With this configuration, only the maximum value of each differential output can be output to the detector, so that the detector needle is not shaken and is extremely stable.
[0046]
【The invention's effect】
As described above, according to the present invention, the progress of bearing wear can be easily and reliably detected using an electrical detection method without being substantially affected by the groove harmonic component of the canned motor and the frequency component of the swell. Can be monitored.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a canned motor pump according to a first embodiment of the present invention.
2A is an enlarged view showing the inductive sensor mounting portion of FIG. 1, and FIG. 2B is a side view thereof.
FIG. 3 is an enlarged view showing an inductive sensor having a shielding structure.
FIG. 4 is a processing circuit diagram showing a processing circuit of a bearing wear detector.
FIG. 5 is a graph for explaining the frequency attenuated by the filter.
FIG. 6 is a diagram showing an example of detection of bearing wear in the radial direction.
FIG. 7 is a diagram illustrating an example of detection of bearing wear in the axial direction.
FIG. 8 is a cross-sectional view showing an inductive sensor mounting portion of a canned motor pump according to a second embodiment of the present invention.
9A is a graph showing the relationship between the radial wear amount and the differential output, and FIG. 9B is a graph showing the relationship between the axial wear amount and the differential output.
FIG. 10 is a processing circuit diagram showing a processing circuit of a bearing wear detector of a canned motor pump according to a third embodiment of the present invention.
FIG. 11 is a cross-sectional view showing a conventional canned motor pump.
12A is an enlarged view showing the inductive sensor mounting portion of FIG. 11, and FIG. 12B is a side view thereof.
FIG. 13 is a processing circuit diagram showing a processing circuit of a conventional bearing wear detector.
FIG. 14 is a diagram showing an example of detection of conventional bearing wear in the radial direction.
FIG. 15 is a diagram showing a detection example of conventional bearing wear in the radial direction.
FIGS. 16A and 16B are diagrams showing examples of conventional bearing wear output, where FIG. 16A shows a radial wear amount, and FIG. 16B shows an axial wear amount.
[Explanation of symbols]
1 Pump casing
2 impeller
3 Casing cover
4 distribution holes
5 Rotor
6 Distance piece (sleeve)
7a, 7b Thrust board
8a, 8b Shaft sleeve
9a, 9b Bearing
10 Rotor
11 End cover
12a, 12b can
13 Stator
14 Through hole
22,23 volts
24 Motor frame
25a, 25b Frame side plate
S1, S2, S3, S4 Inductive sensor
δ1, δ2 clearance

Claims (4)

In a canned motor pump in which an impeller is fixed to one end of a rotor and the rotor is supported by bearings arranged on both sides of the impeller side and the opposite impeller side, a notch portion is formed on a part of the end surface of the stator core of the canned motor The notch has an iron core and a detection coil wound around the iron core, and the iron core around which the detection coil is wound extends radially toward the outer peripheral side of the stator. A plurality of inductive sensors having a shielding part that absorbs magnetic flux formed by the load current of the rotor and is bent again in a letter shape toward the inner periphery of the stator, and the detection surface of the sensor is the end of the rotor core It is arranged so as to overlap at least part of the outer peripheral surface of the unit along the axial direction, and is passed through a low-pass filter circuit that attenuates frequency components of several tens of Hz or more and a high-pass filter circuit that attenuates frequency components of several Hz or less. Said invitation Canned motor pump being characterized in that so as to monitor the wear state of the bearing from the output of the mold sensors to detect the position of the rotor.   2. The canned motor according to claim 1, wherein the inductive sensor is arranged such that a detection surface of the inductive sensor overlaps with an outer peripheral surface of an end portion of the rotor core about half along the axial direction. pump.   2. The cand according to claim 1, wherein the inductive sensor is arranged such that a detection surface of the inductive sensor overlaps with an outer peripheral surface of the end of the rotor core substantially along the entire axial direction. Motor pump.   The canned motor pump according to any one of claims 1 to 3, further comprising a circuit that outputs only a maximum value of an output of the inductive sensor.

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