JP3548661B2 - Bearing wear monitoring device for canned motor - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a device for monitoring bearing wear from displacement of a rotor caused by bearing wear of a canned motor.
[0002]
[Prior art]
The canned motor is applied to one part of a plant as a pump motor, and high reliability is required. Therefore, a device for externally monitoring the wear state of the bearing supporting the rotor is indispensable.
6 and 7 show an example of a conventional bearing wear monitoring device.
The detection coils 2a and 2b wound in the longitudinal direction of the iron core teeth of the stator 1 opposed to each other by 180 degrees are connected so as to output the differential output, and the output is read by the voltmeter 3.
[0003]
In this case, the voltage induced in the detection coils 2a and 2b by the rotation of the rotor 4 is a voltage obtained by superimposing a harmonic voltage under the influence of the rotor groove 4a on a fundamental wave voltage synchronized with the power supply frequency. Are connected so that the outputs of the detection coils 2a and 2b provided in the differential are differential, the voltmeter 3 eliminates the fundamental wave voltage and displays the difference between the instantaneous values of the high-frequency voltage as the output voltage. . Then, as shown in FIG. 7, when the gap d1 between the stator 1 and the rotor 4 becomes large and the gap d2 becomes small (the rotor 4 is displaced in the radial direction) as shown in FIG. The voltmeter 3 displays the differential output with the increased harmonic voltage of the coil 2b.
[0004]
[Problems to be solved by the invention]
In the conventional bearing wear monitoring device, it is possible to monitor only the radial wear state of the bearing that caused the rotor 4 to be displaced in the radial direction, and it is possible to monitor the axial wear state of the bearing. There was a disadvantage that it could not be monitored.
In the canned motor pump, the direction of the load applied to the rotor shaft changes depending on the properties of the transport fluid, the fluid pressure, and the like. Therefore, it is desired to grasp the detailed wear state of the bearing.
[0005]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a bearing wear monitoring device for a canned motor that enables monitoring of bearing wear resulting from radial displacement and axial displacement of the rotor.
[0006]
[Means for Solving the Problems]
The invention of the present application is directed to a large loop coil having a figure-eight shape, which intersects at notched grooves provided at positions deviated from the longitudinal center of the stator core teeth and is installed so as to wind both end faces of the core teeth. A first detection coil composed of a small loop coil, and an iron core tooth 180 degrees opposite to the first detection coil, are relatively opposite to the installation positions of the large loop coil and the small loop coil of the first detection coil. And a second detection coil comprising a large loop coil and a small loop coil, which are installed in the embodiment, are connected so as to output a differential combined output, and an output display is connected to the differential output connection circuit. Thereby, the above object is achieved (the invention according to claim 1).
[0007] The invention of the present application is also directed to an axial displacement and a radial displacement of the rotor by adjusting the lengths of the large loop coil and the small loop coil of the first detection coil and the second detection coil. The object is achieved by enabling the detection sensitivity to be adjusted (the invention according to claim 2).
[0008]
[Action]
The invention according to claim 1 provides a differential output between a large loop coil and a small loop coil having a figure-eight shape of the first detection coil accompanying the axial displacement and the radial displacement of the rotor, and the differential output of the second detection coil. By detecting the differential combined output of the difference output between the large loop coil and the small loop coil, the wear of the bearing in the axial direction and the radial direction is monitored.
According to the second aspect of the invention, the axial and radial wear of the bearing is accurately monitored.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
First, a method of installing the detection coil on the iron core teeth of the stator will be described with reference to FIG. As shown in FIG. 1A, a notch groove 2b is formed at a point P2 (point deviated to the left in the figure) deviated from the center in the longitudinal direction of the iron core teeth 2a of the stator 1, and this notch groove 2b And a second detection coil C2 composed of a large loop coil C2L and a small loop coil C2S that are twisted in an eight-letter shape so as to wind around both end surfaces of the iron core teeth 2a (notched groove 2b) Each of the large and small loop coils C2L and C2S crossing each other is fixed with, for example, resin or the like).
[0010]
Then, as shown in FIG. 1 (B), the iron core tooth 1a 180 degrees opposite to the iron core tooth 2a on which the second detection coil C2 is installed is located at a position P1 relatively opposite to the installation position of the point P2. A first detection coil C1 composed of a large loop coil C1L and a small loop coil C1S twisted in a figure-eight shape in the same manner as the second detection coil C2 is installed in the provided notch groove 1b.
[0011]
FIG. 2 shows a connection diagram of the first and second detection coils C1 and C2. On the induction motor side, the first detection coil C1 (the combined output between the large loop coil C1L and the small loop coil C1S is a differential output). Output) and a second detection coil C2 (the combined output between the large loop coil C2L and the small loop coil C2S is a differential output) so as to output a differential output (the first detection coil C1). And the polarity is changed to connect the second detection coil C2), and the output display V is connected to this connection circuit.
[0012]
Next, detection when the rotor is displaced in the axial direction from the normal position (due to axial displacement of the bearing) will be described.
As shown in FIG. 3, when the rotor is displaced in the + direction (leftward) from the normal position 0, the induced voltage of the large loop coil C1L of the first detection coil C1 is not changed, and the induced voltage of the small loop coil C1S is not changed. As the voltage decreases, the output of the difference coil C1 increases as shown in FIG.
Further, since the induced voltage of the large loop coil C2L of the second detection coil C2 decreases and the induced voltage of the small loop coil C2S does not change, the output of the difference coil C2 decreases as shown in FIG.
Therefore, the differential combined output of the first and second detection coils C1 and C2 is shown as the output characteristic in FIG. 4, and this output is displayed on the output display V to detect the axial displacement of the rotor. , The axial wear of the bearing can be monitored.
Further, even when the rotor is displaced in the negative direction (rightward) in FIG. 3, the output characteristic of FIG. 4 showing the differential combined output accompanying the increase and decrease of the output of each of the first and second detection coils C1 and C2. Can be detected.
[0013]
Detection when the rotor is displaced in the radial direction from the normal position (due to the radial displacement of the bearing) will be described.
As shown in FIG. 3, when the rotor is displaced in the + direction (upward) from the normal position 0, the induced voltages of the large loop coil C1L and the small loop coil C1S of the first detection coil C1 both increase, and The output of the coil C1 increases as shown in FIG.
Further, the induced voltages of the large loop coil C2L and the small loop coil C2S of the second detection coil C2 both decrease, and the output of the difference C2 decreases as shown in FIG. Therefore, the differential combined output of the first and second detection coils C1 and C2 is shown as the output characteristic in FIG. 5, and this output is displayed on the output display V to detect the radial displacement of the rotor. , Can be monitored with radial wear of the bearing.
In addition, even when the rotor is displaced in the negative direction (downward) in FIG. 3, the detection is performed based on the output characteristics in FIG. 5 showing the differential combined output accompanying the increase and decrease in the output of the first and second detection coils C1 and C2. can do.
[0014]
【Example】
The detection sensitivity of the axial displacement and the radial displacement of the rotor can be adjusted by the ratio of the length of the large loop coil to the length of the small loop coil of each of the first and second detection coils. Are wound twice to increase the induced voltage and increase the output difference between the two coils, thereby enabling detection with high sensitivity.
Further, a notch groove is provided at the center of the iron core teeth of the stator, and a detection coil having a loop coil of the same length intersecting with the notch groove is installed at a position 180 degrees opposite to the iron core teeth, so that the axial direction of the rotor can be improved. Only displacement can be detected.
[0015]
【The invention's effect】
According to the first aspect of the present invention, it is possible to efficiently monitor the axial wear and the radial wear of the bearing, which cause the axial displacement and the radial displacement of the rotor, by using two sets of detection coils.
The invention according to claim 2 can accurately detect the axial displacement and the radial displacement of the rotor.
[Brief description of the drawings]
1A and 1B show a method of installing a detection coil on a core tooth of a stator. FIG. 1A is a perspective view, and FIG. 1B is a side sectional view.
FIG. 2 is a connection diagram of a detection coil.
FIG. 3 is a diagram illustrating detection of axial displacement and radial displacement of a rotor.
FIG. 4 is a diagram illustrating an axial displacement of a rotor and an output characteristic of a detection coil;
FIG. 5 is a diagram illustrating a radial displacement of a rotor and an output characteristic of a detection coil.
FIG. 6 is an explanatory view showing a conventional installation of a detection coil on a stator for detecting bearing wear.
FIG. 7 is an explanatory diagram of a detection circuit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Stator 1a Stator iron core teeth 1b, 2b Notch groove c1 First detection coil C1L Large loop coil C1S Small loop coil c2 Second detection coil C2L Large loop coil C2S Small loop coil

Claims (2)

An eight-shaped large loop coil and a small loop coil which intersect at notch grooves provided at positions deviated from the center in the longitudinal direction of the stator iron core teeth and are installed so as to wind both end surfaces of the iron core teeth. A first detection coil composed of: and the iron core teeth 180 degrees opposite to the first detection coil are installed in a manner that is relatively opposite to the installation positions of the large loop coil and the small loop coil of the first detection coil. And a second detection coil including a large loop coil and a small loop coil. The second detection coil is connected such that a differential combined output is output, and an output indicator is connected to the differential output connection circuit. Bearing monitoring device for canned motors. 2. The detection sensitivity of the axial displacement and the radial displacement of the rotor can be adjusted by adjusting the length of each of the large loop coil and the small loop coil of the first detection coil and the second detection coil. 4. The device for monitoring bearing wear of a canned motor according to claim 1.

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