JP6029888B2 - Motor diagnostic device, method and program - Google Patents

Description

  The present invention relates to a motor diagnostic technique that focuses on wear generated in a fitting portion of a bearing constituting a motor.

In plants such as power plants, motor vibration data is recorded constantly or periodically. Based on the change in the level of recorded data and the change in frequency characteristics, the presence or absence of abnormality or deterioration occurring in the motor is detected at an early stage.
Furthermore, the trend of changes in the recorded data is analyzed, and the time for overhauling the motor is estimated. The determination of motor abnormality and deterioration is based on criteria such as the International Organization for Standardization (ISO) and standard values obtained from a plurality of measurement data, and the conditions for issuing an alarm and stopping operation are determined.

It is known that when the motor is abnormal or deteriorated, the vibration level changes and a characteristic change appears in the frequency characteristics. A change is observed in the frequency component of the vibration depending on an integral multiple of the motor rotation speed, the number of balls of the rolling bearing, and the like. And the change of these frequency components is monitored and the presence or absence of abnormality and deterioration is judged (for example, patent document 1).
Also, the presence or absence of abnormality or deterioration is determined by utilizing the fact that a change is observed in a specific frequency component in the current waveform of the motor.

JP 2009-109350 A

The above-described prior art is effective for determining abnormality or deterioration of a motor due to scratches on a rolling bearing, bending or missing of a rotating shaft, or damage to a rotor or a stator.
When these scratches, damages, etc. occur, the corresponding frequency component changes are immediately detected as changes in monitoring data such as vibrations and currents, so that the occurrence of an abnormality is determined early.

By the way, the fitting part between the rolling bearing and the housing in this motor has a loose dimension so that the rolling bearing can move in the axial direction in order to ensure the axial clearance of the rotating shaft that is thermally expanded and contracted.
If the fitting part gradually wears due to repeated thermal expansion and contraction, or if there is a poor installation (centering deviation) between the motor and the load device (for example, pump) connected to the motor, vibration of the motor's rotating shaft As the load increases, the load applied to the rolling bearing increases, and wear may occur in the fitting portion. As the wear of the fitting portion progresses, the rolling bearing becomes easy to move, so that the wear further proceeds.
When the wear of the fitting portion progresses, the rotor and stator of the motor may approach and seize.

However, such wear of the fitting portion of the motor bearing is difficult to find by monitoring the vibration and current in the above-described prior art.
At the time of overhauling the motor, the size of the fitting portion of the housing is measured to check whether there is abnormal wear. As described above, the wear of the fitting portion is found only by periodic disassembly and inspection.
However, even if there is no abnormality in the latest overhaul and inspection, there is a concern that during the operation, the wear of the fitting portion proceeds and a motor failure occurs.

  The present invention has been made in view of such circumstances, and can detect the progress of wear of the fitting portion of the bearing outer ring during operation of the motor, thereby preventing the occurrence of defects such as seizure. An object is to provide a motor diagnostic technique.

A rotating shaft that is rotatably supported by a housing via a bearing, a stator that is fixed to the housing, and a rotor that applies rotational torque to the rotating shaft by electromagnetic interaction with the stator. In the motor diagnosis apparatus for a motor to be operated, at least one of a displacement sensor for measuring a radial displacement amount of the rotating shaft of the motor and a magnetic flux sensor for measuring a leakage flux of the motor, the rotating shaft of the motor An input unit that inputs a continuous waveform signal reflecting both the actual rotation of the bearing and the rotation of the outer ring of the bearing, and a low frequency component having a frequency lower than the actual rotation of the motor is extracted from the waveform signal. And a wear determination unit that determines presence or absence of wear on the inner peripheral surface of the fitting portion of the housing and the outer peripheral surface of the outer ring of the bearing based on the low frequency component Characterized in that it comprises a.
Furthermore, a rotating shaft that is rotatably supported on the housing via a bearing, a stator that is fixed to the housing, and a rotor that applies a rotational torque to the rotating shaft by electromagnetic interaction with the stator. In the motor diagnostic device for a motor constituted by, an ultrasonic sensor for detecting an echo of an ultrasonic wave transmitted to a region including the fitting portion of the housing, and an eddy current generated in the region including the fitting portion are detected. An input unit that inputs a discrete waveform signal reflecting the rotation of the outer ring of the bearing that is linked to the movement of the rotation shaft of the motor from at least one of the eddy current sensors that performs, and the motor from the waveform signal An extraction unit that extracts a low frequency component observed at a time interval corresponding to a frequency lower than the actual rotation of the actual rotation, and a fitting portion of the housing based on the low frequency component A circumferential surface and the wear judgment unit for determining the presence or absence of wear on the outer peripheral surface of the outer ring of the bearing, characterized in that it comprises a.

  According to the present invention, there is provided a motor diagnosis technique capable of detecting the progress of wear of the fitting portion of the bearing outer ring during operation of the motor and preventing the occurrence of problems such as seizure.

The block diagram which shows embodiment of the motor diagnostic apparatus which concerns on this invention. Explanatory drawing of the rotational movement of the bearing in the wear | fitted fitting part. (A) is a graph which shows the low frequency component extracted from the waveform signal which the sensor observed in time series, (B) is a graph which shows the frequency spectrum of a waveform signal. (A) is a figure which shows the example of an observation of the waveform signal by an ultrasonic sensor, (B) is a graph which shows the timing when the echo wave from the outer ring inner peripheral surface of a bearing is observed. The block diagram which shows the example of mounting | wearing of the load part which makes the rotation balance of a motor imbalance.

(First embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
As shown in FIG. 1, the motor diagnostic apparatus 10 includes an input unit 11 that inputs a waveform signal 41 that reflects the movement of the rotating shaft 24 of the motor 20 from the sensor 40, and a frequency that is higher than the actual rotation of the motor from the waveform signal 41. And a wear determination unit 15 that determines the presence or absence of wear in the fitting portion 22 of the bearing 30 of the motor 20 based on the low frequency component.

  Further, the motor diagnostic device 10 inputs the dimensions of the fitting portion 22 (the outer diameter E of the outer ring 32 of the bearing 30 or the inner diameter D on the housing 21 side), the actual rotation frequency N of the motor, and the frequency F of the low frequency component. The calculation unit 16 for calculating the wear amount C in the fitting unit 22 is further provided.

  The motor 20 rotates on the rotating shaft 24 by electromagnetic interaction between a rotating shaft 24 rotatably supported by the housing 21 via a bearing 30, a stator 26 fixed to the housing 21, and the stator 26. And a rotor 25 for applying torque.

  The bearing (rolling bearing) 30 is configured so that the outer peripheral surface is in contact with the inner ring 34 that rotates integrally with the inner peripheral surface of the rotating shaft 24 fitted therein and the inner peripheral surface 23 of the fitting portion 22 on the housing 21 side. An outer ring 32 provided, a rolling element 31 that is supported by the inner ring 34 and the outer ring 32 and relatively rotates both with low friction, and a holder 33 that holds the plurality of arranged rolling elements 31 so as not to contact each other. Has been.

The fitting dimension between the inner peripheral surface 23 of the fitting portion 22 on the housing 21 side and the outer peripheral surface of the outer ring 32 is made looser than the fitting dimension between the outer peripheral surface of the rotating shaft 24 and the inner peripheral surface of the inner ring 34. Is set.
Thereby, when thermal expansion and contraction occurs in the axial direction of the rotating shaft 24, the bearing 30 is displaced relative to the housing 21, thereby releasing stress.

FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1 and illustrates a state in which the outer ring 32 of the bearing rotates and moves in the fitting portion 22 where the inner peripheral surface 23 is worn.
In a state in which a radial force is applied to the rotating shaft 24, the outer ring 32 is biased to contact one side of the housing 21 and forms a gap on the opposite side.
The outer ring 32 rotates the inner peripheral surface 23 of the fitting portion 22 by centrifugal force applied to the rotating shaft 24 by driving the motor.
When such a rotational movement of the outer ring 32 is repeated, wear of the inner peripheral surface 23 of the fitting portion 22 proceeds, and the gap widens. When the gap is formed, the outer ring 32 becomes easier to move, wear progresses at an accelerated rate, and the gap widens.
When the gap increases in this way, the distance between the rotor 25 and the stator 26 shown in FIG. 1 is narrowed, and both may come into contact with each other and burn.

In FIG. 1, the sensor 40 is exemplified by a displacement sensor 40 a that measures the amount of displacement in the radial direction of the rotating shaft 24 of the motor 20 and a magnetic flux sensor 40 b that measures the leakage flux of the motor 20. In the actual diagnosis, any one of the displacement sensor 40a and the magnetic flux sensor 40b may be installed.
Further, the sensor 40 is not limited to these, and may be appropriately employed as long as it detects a physical quantity reflecting the movement of the rotating shaft 24 of the motor 20.

The displacement sensor 40a includes, for example, a sensor that detects the reflected light of the laser beam irradiated on the outer peripheral surface of the rotating shaft 24 and measures the amount of displacement of the rotating shaft 24 in the radial direction from the change in the optical path length.
The displacement sensor 40a is preferably a non-contact type, but may be a contact type.
The magnetic flux sensor 40 b detects a change in density of the magnetic flux leaked to the outside of the housing 21 among the magnetic flux generated by the electromagnetic interaction between the stator 26 and the rotor 25.
Such a change in the density of the magnetic flux depends on the relative position change between the stator 26 and the rotor 25, and thus reflects the movement of the rotating shaft 24.

The input unit 11 inputs an analog waveform signal 41 output from the sensor 40 to the A / D conversion unit 12 and performs digital conversion. The digitally converted waveform signal 41 is recorded in the recording unit 13.
Note that the A / D conversion unit 12 and the recording unit 13 do not need to be disposed inside the motor diagnostic device 10 and may be integrated with the sensor 40.

The graph of FIG. 3A shows a low-frequency component that is extracted from the waveform signal 41 by the extraction unit 14 configured by, for example, a low-pass filter or the like and depends on the wear of the fitting unit 22. The graph in FIG. 3B shows the frequency spectrum of the waveform signal 41.
Thus, the waveform signal 41 recorded in time series in the recording unit 13 includes a low-frequency component that depends on the wear amount of the fitting unit 22 with the frequency N of the actual rotation of the motor 20 as a main component. .
The extraction unit 14 is not particularly limited as long as it can extract a low-frequency component having a frequency lower than the actual rotation of the motor 20 from the waveform signal 41, and extracts the low-frequency component from the result of Fourier transforming the waveform signal 41. May be.

  The wear determination unit 15 determines whether or not there is wear in the fitting unit 22 of the bearing 30 of the motor 20 based on whether or not the spectrum of the low frequency component is observed. And when abnormality determination is made, the display part 17 displays the alarm to that effect. From this alarm display, it is possible to determine whether or not the motor can be operated or whether or not an overhaul is required.

Here, when the inner diameter D of the fitting portion 22 on the housing 21 side and the outer diameter E of the outer ring 32 are set, a gap C (C = DE) between the housing 21 and the outer ring 32 is obtained.
In other words, the rotational speed R of the rotating shaft 24 (inner ring 34) per rotation of the outer ring 32 is expressed by equation (1). Furthermore, when the frequency N of the actual rotation of the motor 20 is assumed, the rotation frequency F of the outer ring 32 is expressed by equation (2). Further, the time T required for the outer ring 32 to make one rotation is expressed by equation (3). Then, equation (4) is derived from equations (1) and (2).

R = πD / πC = D / C (1)
F = N / R (2)
T = 1 / F (3)
C = D × F / N = E / (N / F-1) (4)

Here, the actual rotation frequency N of the motor 20 and the rotation frequency F of the outer ring 32 correspond to the frequency N of the main component of the waveform signal and the frequency (1 / T) of the low frequency component in the frequency spectrum (FIG. 3), respectively. ing. A gap C between the housing 21 and the outer ring 32 corresponds to the wear amount C of the fitting portion 22.
Here, for example, when D = 100 mm, C = 0.1 mm, and N = 50 Hz, F = 0.05 Hz from Expressions (1) to (3).
Thus, it can be seen that the rotation frequency F of the outer ring 32 is very low as compared with the actual rotation frequency N of the motor 20.

The calculation unit 16 calculates the dimensions of the fitting portion 22 (the outer diameter E of the outer ring 32 of the bearing 30 or the inner diameter D of the housing 21), the frequency N of the actual rotation of the motor, and the frequency F (1 / T) of the low frequency component. And the wear amount C in the fitting portion 22 is calculated based on the equation (4). The calculation formula for the wear amount C is not limited to the formula (4).
Here, since E (D) is determined from the bearing specifications and N is determined from the operating conditions, the wear amount C is calculated and displayed on the display unit 17 when the wear determination unit 15 determines F (<N). As described above, the wear amount of the fitting portion 22 is quantitatively derived while continuing the motor operation, so that it is possible to estimate the progress of wear and estimate the time when replacement is necessary.

  In addition to the displacement sensor 40a and the magnetic flux sensor 40b as described above, the sensor 40 is, for example, an ultrasonic sensor 40c (FIG. 4) for detecting an echo of an ultrasonic wave transmitted to a region including the fitting portion 22, An eddy current sensor (not shown) that detects eddy currents generated in the region including the portion 22 can be used.

FIG. 4A is a diagram illustrating an example of observation of a waveform signal by the ultrasonic sensor 40c.
The ultrasonic sensor 40c is installed outside the fitting portion 22 of the housing. When the inner peripheral surface of the fitting portion 22 is worn and a gap is generated, the outer ring 32 rotates and there is a gap immediately below the ultrasonic sensor 40c (upper side in FIG. 4A), and there is a gap immediately below the gap. If it does not exist (lower side in FIG. 4A) appears.

When there is a gap immediately below the ultrasonic sensor 40c as shown in the upper side of FIG. 4A, only the echo wave 43 from the inner peripheral surface of the fitting portion 22 of the housing is observed as the waveform signal 41c.
On the other hand, when there is no gap immediately below the ultrasonic sensor 40c as in the lower side of FIG. 4A, in addition to the echo wave 43 from the inner peripheral surface of the fitting portion 22, An echo wave 44 is also observed.

FIG. 4B shows the timing at which an echo wave 44 from the inner peripheral surface of the outer ring 32 of the bearing is observed. The interval T at which the echo wave 44 is observed corresponds to the time T required for the outer ring 32 to make one rotation on the inner peripheral surface of the fitting portion 22.
Thereby, the wear amount C of the fitting part 22 can be calculated | required based on said Formula (3) (4).

The eddy current sensor (not shown) is installed outside the fitting portion 22 of the housing, like the ultrasonic sensor 40c. And the eddy current which generate | occur | produces directly under an eddy current sensor fluctuates synchronizing with the outer ring | wheel 32 rotating the internal peripheral surface of the fitting part 22. FIG. Then, the period T of the waveform signal of the varying magnetic field excited in synchronization with this varying eddy current is derived.
And the wear amount C of the fitting part 22 can be calculated | required based on said Formula (3) (4).

FIG. 5 shows an example in which the load unit 27 is mounted to make the rotational balance of the motor unbalanced.
By providing such a load portion 27, the centrifugal force can be exerted more strongly in the radial direction of the rotating shaft 24, and the rotational movement of the outer ring 32 can be detected with higher sensitivity in the sensor 40, and the wear of the outer ring 32 can be detected with higher accuracy. Judgment is possible.

  According to the motor diagnostic device of at least one embodiment described above, it is possible to detect the wear of the fitting portion of the bearing outer ring without disassembling the motor and to quantitatively grasp the amount of wear. For this reason, it is possible to prevent malfunctions of the motor and to make the maintenance work more efficient by predicting the overhaul time.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

The components of the motor diagnostic device can also be realized by a computer processor and can be operated by a motor diagnostic program.
In this case, a waveform signal from the sensor 40 is input to a general-purpose computer, and the above-described wear determination and wear amount calculation are performed by a processor operated by a motor diagnosis program.

  DESCRIPTION OF SYMBOLS 10 ... Motor diagnostic apparatus, 11 ... Input part, 12 ... A / D conversion part, 13 ... Waveform signal recording part (recording part), 14 ... Low frequency component extraction part (extraction part), 15 ... Wear determination part (determination part) ), 16 ... Wear amount calculating section (calculating section), 17 ... Display section, 20 ... Motor, 21 ... Housing, 22 ... Fitting section, 23 ... Inner peripheral surface, 24 ... Rotating shaft, 25 ... Rotor, 26 ... Stator, 27 ... load section, 30 ... bearing, 31 ... rolling element, 32 ... outer ring, 33 ... retainer, 34 ... inner ring, 40 ... sensor, 40a ... displacement sensor (sensor), 40b ... magnetic flux sensor (sensor), 40c ... Ultrasonic sensor (sensor), 41 ... Waveform signal, 41c ... Waveform signal, 43 ... Echo wave from inner peripheral surface of fitting part, 44 ... Echo wave from inner peripheral surface of outer ring of bearing, E ... Outer ring , N ... actual rotation frequency of motor, F ... rotation frequency of outer ring (low frequency component of Wave number), C ... housing and the outer ring gap (wear amount), D ... housing side of the inner diameter of the fitting portion.

Claims (6)

A rotating shaft that is rotatably supported by a housing via a bearing, a stator that is fixed to the housing, and a rotor that applies rotational torque to the rotating shaft by electromagnetic interaction with the stator. In the motor diagnostic device for the motor to be used,
From at least one of a displacement sensor that measures the amount of displacement in the radial direction of the rotating shaft of the motor and a magnetic flux sensor that measures the leakage magnetic flux of the motor, the actual rotation of the rotating shaft of the motor and the interlocking with the actual rotation An input unit for inputting a continuous waveform signal reflecting both rotation of the outer ring of the bearing ;
An extraction unit for extracting a low frequency component having a frequency lower than the actual rotation of the motor from the waveform signal;
A motor diagnostic apparatus comprising: a wear determination unit that determines presence or absence of wear on an inner peripheral surface of the fitting portion of the housing and an outer peripheral surface of the outer ring of the bearing based on the low frequency component. A rotating shaft that is rotatably supported by a housing via a bearing, a stator that is fixed to the housing, and a rotor that applies rotational torque to the rotating shaft by electromagnetic interaction with the stator. In the motor diagnostic device for the motor to be used,
From at least one of an ultrasonic sensor that detects an echo of an ultrasonic wave transmitted to a region including the fitting portion of the housing and an eddy current sensor that detects an eddy current generated in the region including the fitting portion , An input unit for inputting a discrete waveform signal reflecting the rotation of the outer ring of the bearing interlocked with the movement of the rotating shaft of the motor;
An extraction unit for extracting a low frequency component observed at a time interval corresponding to a frequency lower than the actual rotation of the motor from the waveform signal;
A motor diagnostic apparatus comprising: a wear determination unit that determines presence or absence of wear on an inner peripheral surface of the fitting portion of the housing and an outer peripheral surface of the outer ring of the bearing based on the low frequency component. 3. The motor according to claim 1, further comprising a calculation unit that inputs a dimension of the fitting part, a frequency of the actual rotation, and a frequency of the low frequency component and calculates a wear amount in the fitting part. Diagnostic device.   The motor diagnostic apparatus according to any one of claims 1 to 3, wherein a load portion that makes the rotation balance of the rotation shaft of the motor unbalanced is provided. A rotating shaft that is rotatably supported by a housing via a bearing, a stator that is fixed to the housing, and a rotor that applies rotational torque to the rotating shaft by electromagnetic interaction with the stator. In the motor diagnosis method for the motor to be used,
The interlocking at least one sensor of the displacement sensor and the magnetic flux sensor for measuring the leakage flux of the motor for measuring the radial displacement of the rotating shaft of the motor, the actual rotation and to the rotation shaft of the motor Inputting a continuous waveform signal reflecting both rotation of the outer ring of the bearing ;
Extracting a low frequency component having a frequency lower than the actual rotation of the motor from the waveform signal;
Determining whether there is wear on the inner peripheral surface of the fitting portion of the housing and the outer peripheral surface of the outer ring of the bearing based on the low-frequency component. A rotating shaft that is rotatably supported by a housing via a bearing, a stator that is fixed to the housing, and a rotor that applies rotational torque to the rotating shaft by electromagnetic interaction with the stator. In the motor diagnosis method for the motor to be used,
From at least one of an ultrasonic sensor that detects an echo of an ultrasonic wave transmitted to a region including the fitting portion of the housing and an eddy current sensor that detects an eddy current generated in the region including the fitting portion , Inputting a discrete waveform signal reflecting the rotation of the outer ring of the bearing in conjunction with the movement of the rotating shaft of the motor;
Extracting a low frequency component observed at a time interval corresponding to a frequency lower than the actual rotation of the motor from the waveform signal;
Determining whether there is wear on the inner peripheral surface of the fitting portion of the housing and the outer peripheral surface of the outer ring of the bearing based on the low-frequency component.

Images