State monitoring device, pump, state monitoring program, state monitoring method, and frequency band setting method

Abstract

Monitor the state of the pump to be monitored, which appears as a periodic displacement of the position of the rotor. 【Solution means】The state monitoring device 4 according to the present invention monitors the state of the pump to be monitored based on detection signals output from a plurality of detection coils C1 to C4 that detect a magnetic flux change corresponding to the displacement of the position of the rotor with respect to the stator of the motor of the pump. The state monitoring device 4 includes an acquisition unit 420 that acquires at least one of a first composite signal and a second composite signal over time, a spectrum generation unit 421 that executes FFT processing on the signal acquired by the acquisition unit to generate a monitoring spectrum, a storage unit 43 that stores a monitoring frequency band preset for the monitoring target and a reference spectrum that is a comparison target of the monitoring spectrum, and a determination unit 425 that determines whether the state of the monitoring target corresponding to the monitoring frequency band is normal or abnormal based on a comparison between the latest monitoring spectrum and the reference spectrum in the monitoring frequency band.

Description

Technical Field

[0001] The present invention relates to a state monitoring device, a pump, a state monitoring program, a state monitoring method, and a frequency band setting method.

Background Art

[0002] Pumps are used for a relatively long period of time to pump liquids in factories, plants, etc. Therefore, a load is applied to the components of the pump, particularly the rotating components (e.g., bearings, etc.) for a long period of time. When these components are damaged, the operation of the pump stops. Therefore, monitoring the state of these components is important. As a device for monitoring the state of pump components, a device that electrically monitors the wear state of bearings is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The device disclosed in Patent Document 1 measures the change in magnetic flux during the rotation of the rotor using the detection signal of the detection coil attached to the end of the stator, thereby measuring the displacement of the positional relationship between the rotor and the stator in the radial and thrust directions caused by bearing wear. This displacement corresponds to the amount of bearing wear. Therefore, the device can accurately monitor the amount of bearing wear. The inventor of the present application has come up with the idea that by using this detection signal, it is possible to monitor not only the amount of bearing wear but also the state of a member (monitoring target) that appears as a periodic displacement (i.e., vibration) of the position of the rotor with respect to the stator.

[0005] An object of the present invention is to provide a condition monitoring device, a pump, a condition monitoring program, a condition monitoring method, and a frequency band setting method that can monitor the condition of a monitoring target of a pump that appears as a periodic displacement of the position of a rotor.

Means for Solving the Problems

[0006] A condition monitoring device according to an embodiment of the present invention is a condition monitoring device that monitors the condition of a monitoring target of a pump based on detection signals output from a plurality of detection coils that detect a magnetic flux change corresponding to a displacement of the position of a rotor with respect to a stator of a motor of the pump. The plurality of detection coils are attached to the stator so as to be able to detect the magnetic flux change corresponding to the displacement in the radial direction of the rotor, output a detection signal indicating the magnetic flux change, and include a pair of detection coils whose detection signals are combined. Each of the pair of detection coils is arranged at the same position in the thrust direction of the rotor and at different positions in the circumferential direction of the rotor, and at least one of a first combined signal obtained by combining the detection signals output from the pair of detection coils so as to obtain a difference and a second combined signal obtained by combining the detection signals output from the pair of detection coils so as to be superimposed is acquired over time by an acquisition unit, a spectrum generation unit that executes FFT processing on the signal acquired by the acquisition unit to generate a monitoring spectrum, a storage unit that stores at least one monitoring frequency band preset for the monitoring target and a reference spectrum that is a comparison target of the monitoring spectrum, and a determination unit that determines whether the condition of the monitoring target corresponding to the monitoring frequency band is normal or abnormal based on a comparison between the latest monitoring spectrum and the reference spectrum in the monitoring frequency band.

[0007] A condition monitoring device according to an embodiment of the present invention detects a magnetic flux change corresponding to a displacement of the position of a rotor with respect to a stator of a motor of a pump Ru 1 a plurality of detection coils onlyA state monitoring device that monitors the state of a monitoring target of the pump based on a detection signal output from . The detection coil is attached to the stator so as to be able to detect a magnetic flux change corresponding to the displacement of the rotor in the radial direction, outputs a detection signal indicating the magnetic flux change, and has an acquisition unit that acquires the detection signal over time, a spectrum generation unit that executes FFT processing on the detection signal acquired by the acquisition unit to generate a monitoring spectrum, a storage unit that stores at least one monitoring frequency band preset for the monitoring target and a reference spectrum that is a comparison target of the monitoring spectrum, and a determination unit that determines whether the state of the monitoring target corresponding to the monitoring frequency band is normal or abnormal based on a comparison between the latest monitoring spectrum and the reference spectrum in the monitoring frequency band.

[0008] A pump according to an embodiment of the present invention includes a motor including a rotor, a stator that rotates the rotor, and a rotating shaft that rotates together with the rotor, a bearing that supports the rotating shaft, at least one detection coil that detects a magnetic flux change corresponding to a displacement of the position of the rotor with respect to the stator, and the state monitoring device according to each of the above embodiments that monitors the state of a monitoring target of the pump based on a detection signal of the detection coil.

[0009] A state monitoring program according to an embodiment of the present invention causes a computer to function as the state monitoring device according to each of the above embodiments.

[0010] The state monitoring method according to an embodiment of the present invention is a state monitoring method executed by a state monitoring device that monitors the state of a monitoring target of the pump based on detection signals output from a plurality of detection coils that detect a magnetic flux change corresponding to a displacement of the position of a rotor with respect to a stator of a motor of the pump. The plurality of detection coils are attached to the stator so as to be able to detect the magnetic flux change corresponding to the displacement in the radial direction of the rotor, output a detection signal indicating the magnetic flux change, and include a pair of detection coils whose detection signals are combined. The state monitoring device includes a storage unit that stores at least one monitoring frequency band and a reference spectrum that are preset for the monitoring target. The state monitoring method includes: a signal acquisition step in which the state monitoring device acquires at least one of a first combined signal obtained by combining the detection signals output from the pair of detection coils so as to obtain a difference and a second combined signal obtained by combining the detection signals output from the pair of detection coils so as to be superimposed, over time; a monitoring spectrum generation step in which the state monitoring device executes FFT processing on the signal acquired in the signal acquisition step to generate a monitoring spectrum; and a determination step in which the state monitoring device determines whether the state of the monitoring target corresponding to the monitoring frequency band is normal or abnormal based on a comparison between the latest monitoring spectrum and the reference spectrum in the monitoring frequency band.

[0011] The frequency band setting method according to an embodiment of the present invention is a frequency band setting method for setting a monitoring frequency band of a monitoring target of the pump, which is executed by a state monitoring device that monitors the state of the monitoring target of the pump based on detection signals of at least one detection coil that detects a magnetic flux change corresponding to a displacement of the position of a rotor with respect to a stator of a motor of the pump. The detection coil is attached to the stator so as to be able to detect the magnetic flux change corresponding to the displacement in the radial direction of the rotor, and outputs a detection signal indicating the magnetic flux change. The frequency band setting method includes: a parameter acquisition step in which the state monitoring device acquires a parameter based on the specification of the monitoring target; a theoretical monitoring frequency band calculation step in which the state monitoring device calculates a theoretical monitoring frequency band for each monitoring target based on the parameter; a rotation component acquisition step in which the state monitoring device acquires a rotor rotation component frequency determined by the measured rotation speed of the rotor measured when the pump is operating; a correction value calculation step in which the state monitoring device calculates a correction value based on the rotor rotation component frequency determined by the set rotation speed of the rotor set for the pump and the rotor rotation component frequency determined by the measured rotation speed; and a correction step in which the state monitoring device corrects the theoretical monitoring frequency band with the correction value to calculate the monitoring frequency band.

Effect of the Invention

[0012] The present invention can monitor the state of a monitoring target of a pump that appears as a periodic displacement of the position of a rotor.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Embodiments for Carrying Out the Invention

[0014] Embodiments of a state monitoring device (hereinafter referred to as "this device"), a pump, a state monitoring program (hereinafter referred to as "this program"), a state monitoring method (hereinafter referred to as "this monitoring method"), and a frequency band setting method (hereinafter referred to as "this setting method") according to the present invention will be described below. In the following description, each drawing is referred to as appropriate. In each drawing, the same members and elements are denoted by the same reference numerals, and duplicate descriptions are omitted. Also, the dimensional ratios of the respective elements may be exaggerated for convenience of explanation and are not limited to the ratios shown in each drawing.

[0015] In the following description, a submersible pump is described as an example of the pump according to the present invention. The pump is attached to a storage tank in which a liquefied gas is stored, and pumps the liquefied gas from the storage tank to the outside. That is, the submersible pump is an example of the pump according to the present invention, and the liquefied gas is an example of the liquid to be handled in the present invention.

[0016] In the following description, "downward" is the direction of gravity, and "upward" is the opposite direction of downward.

[0017] ●Pump● ●Configuration of the pump First, the configuration of the pump according to the present invention will be described.

[0018] FIG. 1 is a cross-sectional view of the pump showing an embodiment of the pump according to the present invention. The figure shows a cross-section of the pump 1 cut along the axis of the rotating shaft 30 (described later). The figure shows some members in a non-cross-sectional view.

[0019] The pump 1 discharges the liquid to be handled stored in a storage tank (not shown; the same applies hereinafter) into the pump column C. The pump 1 is housed in the lower part of the pump column C extending from the ceiling of the storage tank into the storage tank and is immersed in the liquid to be handled. The configuration of the pump 1 is common to that of a known submersible pump except for the presence or absence of the present device 4. The pump 1 includes a housing 2, a motor unit 3, the present device 4, impellers 51, 52, and diffusers 61, 62. The pump 1 is an example of the pump according to the present invention.

[0020] The housing 2 houses the motor unit 3, the impellers 51, 52, and the diffusers 61, 62. The shape of the housing 2 is a substantially cylindrical shape along the vertical direction. The housing 2 is provided with a suction port 21 and a discharge port (not shown; the same applies hereinafter). The lower end portion of the housing 2 has a reduced diameter and forms the suction port 21.

[0021] The motor unit 3 is driven at a predetermined drive voltage and drive frequency to rotate the impellers 51 and 52. The motor unit 3 includes a rotating shaft 30, bearings 31 and 32, a rotor 33, and a stator 34.

[0022] The rotating shaft 30 rotates due to the rotation of the rotor 33 and transmits the rotational power to the impellers 51 and 52. The shape of the rotating shaft 30 is cylindrical along the vertical direction. The rotating shaft 30 is inserted through the rotor 33. The lower portion 30a of the rotating shaft 30 extends downward from the rotor 33.

[0023] In the following description, the "thrust direction" is the axial direction of the rotating shaft 30, the "radial direction" is the radial direction of the rotating shaft 30, and the "circumferential direction" is the circumferential direction of the rotating shaft 30.

[0024] The bearing 31 is disposed above the rotor 33 and rotatably supports the rotating shaft 30. The bearing 32 is disposed below the rotor 33 and rotatably supports the rotating shaft 30. The bearing 31 is, for example, a known rolling bearing including an inner ring 31a, an outer ring 31b, a plurality of rolling elements 31c, and a cage (not shown; the same applies hereinafter). The bearing 32 is, for example, a known rolling bearing including an inner ring 32a, an outer ring 32b, a plurality of rolling elements 32c, and a cage (not shown; the same applies hereinafter).

[0025] The rotor 33 rotates due to the rotating magnetic field generated in the stator 34. The shape of the rotor 33 is cylindrical. The rotor 33 includes a plurality (28 in the present embodiment) of rod-shaped rotor bars 33a embedded at equal intervals in the outer peripheral edge portion of the rotor 33 in the circumferential direction. When the bearings 31 and 32 are not worn, the rotor 33 is disposed at the initial position with respect to the stator 34. In the present embodiment, in the radial direction, the "initial position" is a position where the center of the stator 34 and the center of the rotor 33 coincide.

[0026] The stator 34 generates a rotating magnetic field for rotating the rotor 33. The shape of the stator 34 is substantially cylindrical. The stator 34 includes a stator core 34a and a plurality of motor windings 34b.

[0027] The stator core 34a holds the motor winding 34b. The shape of the stator core 34a is cylindrical. The stator core 34a includes a plurality of tooth portions 34c (see FIG. 4; the same applies hereinafter).

[0028] The tooth portion 34c forms a slot 34d (see FIG. 4; the same applies hereinafter) through which the motor winding 34b is inserted. In the circumferential direction, the tooth portions 34c are arranged at equal intervals on the inner peripheral edge of the stator core 34a. The motor winding 34b is inserted into the slot 34d and is connected to a power supply device (not shown) such as an inverter.

[0029] The present device 4 monitors the state of the object to be monitored by detecting a magnetic flux change corresponding to a periodic displacement (mechanical position change: i.e., vibration) in the position of the rotor 33 with respect to the stator 34. The specific configuration of the present device 4 will be described later.

[0030] The "object to be monitored" is an object (a component of the pump 1) whose state is monitored by the present device 4. The object to be monitored includes the rotating shaft 30 and a member (hereinafter referred to as the "displacement member") that is in contact with the rotating shaft 30 and whose position with respect to the stator 34 is periodically displaced in accordance with the rotation of the rotating shaft 30. The displacement members are, for example, the rotor 33, the bearings 31, 32, and the impellers 51, 52. More broadly, the object to be monitored includes a member whose state appears as a periodic displacement in the position of the rotor 33 in the radial direction. For example, when the object to be monitored vibrates and an abnormality (such as wear, breakage, foreign matter adhesion, or an increase in mechanical load) occurs in the object to be monitored, the vibration changes (such as a change in frequency or amplitude). When this vibration is transmitted to the rotor 33, the state appears as a periodic displacement in the position of the rotor 33 in the radial direction.

[0031] The "state" includes normal and abnormal.

[0032] When the rotor 33 rotates, the rotating shaft 30 periodically fluctuates (rotates) at the same rotational speed as that of the rotor 33. The rotating shaft 30 is supported by bearings 31 and 32, and the bearings 31 and 32 have a slight play in the radial direction. Also, although the shape of the rotating shaft 30 is cylindrical, it is not a true cylindrical shape without error. Therefore, when the rotating shaft 30 rotates, the positions of the rotating shaft 30 and the rotor 33 are slightly periodically displaced (vibrated) in the radial direction even if they are normal. Further, the position of the displacement member is periodically displaced in accordance with the rotation of the rotating shaft 30. This periodic displacement of the position appears as the vibration of the rotating shaft 30, that is, the periodic displacement of the position of the rotor 33 in the radial direction. Furthermore, in addition to the displacement member, among the components of the pump 1, the vibration of some components is transmitted to the rotor 33 via the rotating shaft 30 and appears as the periodic displacement of the position of the rotor 33 in the radial direction. Still further, not the components of the pump 1, but the cavitation and pressure fluctuations generated in the liquid to be handled are also transmitted to the rotor 33 via the impellers 51 and 52 and the rotating shaft 30 and appear as the periodic displacement of the position of the rotor 33 in the radial direction. The present device 4 can detect these periodic displacements (vibrations) as the periodic displacement of the position of the rotor 33 in the radial direction by the detection coils C1 to C4 (see FIG. 2).

[0033] The impellers 51 and 52 are attached to the lower part 30a of the rotating shaft 30. The impeller 51 is arranged adjacent to the upper direction of the suction port 21. The impeller 52 is arranged above the impeller 51.

[0034] The diffusers 61 and 62 are attached to the housing 2. The diffuser 61 is arranged between the impellers 51 and 52 and adjacent to them. The diffuser 62 is arranged above the impeller 52 and adjacent to the impeller 52.

[0035] ●Condition Monitoring Device● ●Configuration of the Condition Monitoring Device Next, the configuration of the present device 4 will be described. In the following description, FIG. 1 is referred to as appropriate.

[0036] FIG. 2 is a functional block diagram of the present apparatus 4 showing an embodiment of the present apparatus 4.

[0037] The present apparatus 4 includes four detection coils C1, C2, C3, C4, a connection part 40, signal processing parts 41a and 41b, a control part 42, a storage part 43, and a display part 44. The connection part 40, the signal processing parts 41a and 41b, and the control part 42 are realized by, for example, a microcomputer.

[0038] In the present invention, the motor part 3 may include the detection coils C1 to C4.

[0039] FIG. 3 is a schematic perspective view of the stator core 34a showing the arrangement of the detection coils C1 to C4. FIG. 4 is an enlarged perspective view of part A in FIG. 3.

[0040] The detection coils C1 to C4 detect a magnetic flux change corresponding to a displacement of the position of the rotor 33 with respect to the stator 34 in the radial direction (including a displacement of the positional relationship and a periodic displacement), and output a detection signal indicating the magnetic flux change. The shapes of the detection coils C1 to C4 are flat bobbin shapes. The detection coils C1 to C4 are attached to notches 34e formed at the upper and lower ends of the tooth parts 34c of the stator 34 so as to be able to detect a magnetic flux change corresponding to a displacement of the position of the rotor 33 in the radial direction.

[0041] In the circumferential direction, the detection coils C1 and C2 are attached at equal angular intervals to the upper ends of the tooth portions 34c (the same positions in the thrust direction). That is, the angular interval between the detection coils C1 and C2 in the circumferential direction is "180°", and the detection coil C1 is arranged to face the detection coil C2. In the circumferential direction, the detection coils C3 and C4 are attached at equal angular intervals to the lower ends of the tooth portions 34c. That is, the angular interval between the detection coils C3 and C4 in the circumferential direction is "180°", and the detection coil C3 is arranged to face the detection coil C4. That is, in the radial direction, the detection coils C1 and C3 are arranged to face the corresponding detection coils C2 and C4.

[0042] In the present invention, the detection coil C2 may be arranged at a position different from that of the detection coil C1. That is, for example, the angular interval between the detection coils C1 and C2 in the circumferential direction may be "90°". Here, the angular interval between the detection coils C1 and C2 in the circumferential direction is preferably "90°" or more, and more preferably "180°". When the angular interval between the detection coils C1 and C2 in the circumferential direction is "180°", as will be described later, the fundamental wave components of the respective detection signals are in opposite phases and cancel each other out. This relationship is similarly applicable to the detection coils C3 and C4. Also, the detection coils C3 and C4 may be arranged at positions different from those of the detection coils C1 and C2.

[0043] FIG. 5 is a schematic diagram showing an example of a detection signal.

[0044] The detection signals of the detection coils C1 to C4 include a waveform corresponding to the change in the main magnetic flux of the motor unit 3 (hereinafter referred to as the "fundamental wave component"), and a waveform corresponding to the change in the magnetic flux generated by the induced current flowing through the rotor bar 33a (hereinafter referred to as the "harmonic component"). The fundamental wave component is generated by the drive voltage of the drive power source of the motor unit 3, and its frequency is the same as the drive frequency of the drive voltage. The harmonic component is generated by the induced current flowing through the rotor bar 33a, and its frequency is determined by the drive frequency and the number of rotor bars 33a. That is, for example, under the following conditions (drive frequency: 60 Hz, number of rotor bars 33a: 28), each of the detection coils C1 to C4 detects a change in the magnetic flux due to the rotor bar 33a 28 times during one rotation of the rotor 33. Therefore, the frequency of the harmonic component is "60 Hz × 28 = 1.68 kHz". Thus, the frequency of the fundamental wave component is determined based on the drive frequency. The frequency of the harmonic component is determined based on the drive frequency and the number of rotor bars 33a. Here, the rotation speed of the motor unit 3 (rotor 33) is proportional to the drive frequency. Therefore, in other words, the frequency of the harmonic component is determined based on the rotation speed of the rotor 33 and the number of rotor bars 33a. The frequency of the harmonic component is an example of the rotor rotation component frequency in the present invention.

[0045] In the following description, FIGS. 1 to 3 are mainly referred to. The detection coils C1 to C4 detect the displacement of the position of the rotor 33 in the radial direction (including displacement of the positional relationship and periodic displacement) by detecting the change in magnetic flux corresponding to the displacement of the position of the rotor 33 in the radial direction. The detection coil C1 is electrically connected to the common path Lc1 and the detection coil C2. The detection coil C2 is electrically connected to the signal path L11 via the connection portion 50. The detection coils C1 and C2 are connected in series so that the difference between their detection signals can be obtained (so that the detection signals cancel each other out), and function as a pair of detection coils in the present invention. The detection coil C3 is electrically connected to the common path Lc2 and the detection coil C4. The detection coil C4 is electrically connected to the signal path L12 via the connection portion 50. The detection coils C3 and C4 are connected in series so that their detection signals are superimposed, and function as a pair of detection coils in the present invention. The detection coils C1 and C2 are an example of a pair of first detection coils in the present invention. The detection coils C3 and C4 are an example of a pair of second detection coils in the present invention.

[0046] The signal level of the harmonic component increases in the radial direction when the rotor 33 approaches the detection coils C1 to C4 and decreases when the rotor 33 moves away from the detection coils C1 to C4. On the other hand, the signal level of the fundamental wave component does not increase or decrease. Thus, the detection signals of the detection coils C1 to C4 have the characteristic of changing according to the displacement of the position of the rotor 33 in the radial direction. By using this characteristic of the detection signal, the present invention can monitor the state of the monitoring target that appears as the periodic displacement of the position of the rotor 33 in the radial direction.

[0047] Here, for example, when the rotor 33 approaches the detection coil C1, the increase amount of the signal level of the harmonic component of the detection coil C2 becomes larger as the angular interval between the detection coils C1 and C2 in the circumferential direction becomes smaller than "90°", and approaches the increase amount of the signal level of the harmonic component of the detection coil C1. On the other hand, the decrease amount of the signal level of the harmonic component of the detection coil C2 becomes larger as the angular interval between the detection coils C1 and C2 in the circumferential direction becomes larger than "90°", and approaches the increase amount of the signal level of the harmonic component of the detection coil C1. This relationship is similarly applied to the detection coils C3 and C4.

[0048] When the detection signals of the detection coils C1 and C2 are combined so as to obtain their difference (cancel each other out), in the combined signal (hereinafter referred to as "combined signal (S12)"), the fundamental wave component is canceled out. Also, the difference value of the signal levels of the harmonic components increases as the angular interval between the detection coils C1 and C2 in the circumferential direction approaches "180°". This difference value increases in response to the increase in the displacement amount. In the present embodiment, since the angular interval between the detection coils C1 and C2 in the circumferential direction is "180°", the apparatus 4 can detect the radial displacement amount of the position at the lower part of the rotor 33 based on this difference value. The method for detecting the radial displacement amount is well-known. Therefore, a detailed description thereof is omitted. Thus, the detection coils C1 and C2 output the detection signals that form the basis of the combined signal (S12). The combined signal (S12) is an example of the first combined signal in the present invention.

[0049] On the other hand, when the detection signals of the detection coils C3 and C4 are combined so as to be superimposed (added together), in the combined signal (hereinafter referred to as "combined signal (S34)"), the fundamental wave components are added together, and the signal level becomes approximately twice the signal level of the fundamental wave component of the detection signals. Also, the added value of the signal levels of the harmonic components becomes smaller as the angular interval between the detection coils C3 and C4 in the circumferential direction approaches "180°". Thus, the detection coils C3 and C4 output the detection signals that form the basis of the combined signal (S34). The combined signal (S34) is an example of the second combined signal in the present invention.

[0050] The connection part 40 is an interface to which the detection coils C2 and C4 are connected. The common paths Lc1 and Lc2, the detection coils C2 and C4, and the signal paths L11 and L12 are connected to the connection part 40. The common paths Lc1 and Lc2 are connected to the ground via the connection part 40.

[0051] The signal processing units 41a and 41b execute predetermined signal processing (for example, first filter processing, absolute value processing, second filter processing, envelope processing, differentiation processing, and A / D conversion processing) on each composite signal (S12, S34). The signal processing units 41a and 41b include, for example, a first filter circuit (for example, a band-pass filter or a low-pass filter), an absolute value circuit, a second filter circuit (for example, a low-pass filter), an envelope detection circuit, a differentiation processing, and an A / D conversion circuit. The signal processing unit 41a is connected to the signal path L11 and executes predetermined signal processing on the composite signal (S12). The signal processing unit 41b is connected to the signal path L12 and executes predetermined signal processing on the composite signal (S34).

[0052] Here, each composite signal (S12, S34) is a signal indicating a periodic displacement of the position. By performing differentiation processing on the signal, the signal after the differentiation processing becomes a signal indicating the speed. Further, by performing differentiation processing on the signal indicating the speed, the signal after the differentiation processing becomes a signal indicating the acceleration. Each signal has a vibration phenomenon and a frequency band that it is good at. Therefore, by performing these processes according to the phenomenon to be monitored, the state of the monitoring target can be monitored with higher accuracy.

[0053] The control unit 42 controls the operation of the entire apparatus 4. The control unit 42 includes, for example, a processor such as a CPU (Central Processing Unit) 42a, a volatile memory such as a RAM (Random Access Memory) 42b that functions as a working area of the CPU 42a, and a non-volatile memory such as a ROM (Read Only Memory) 42c that stores various information such as this program. The control unit 42 includes an acquisition unit 420, a spectrum generation unit 421, a first calculation unit 422, a second calculation unit 423, a correction unit 424, a determination unit 425, and a display control unit 426.

[0054] In the control unit 42, this program operates, and this program cooperates with the hardware resources of the apparatus 4 to realize the monitoring method described later. Further, by causing the processor (CPU 42a) constituting the control unit 42 to execute this program, this program causes the same processor to function as the acquisition unit 420, the spectrum generation unit 421, the first calculation unit 422, the second calculation unit 423, the correction unit 424, and the determination unit 425, and can cause the same processor to execute the monitoring method. Furthermore, by causing a computer to execute this program, this program can cause the computer to function as the apparatus 4.

[0055] Note that in the present invention, this program may be stored in the storage unit 43. Further, this program may be stored in a non-temporary storage medium (for example, a CD (Compact Disc), a DVD (Digital Versatile Disc), a USB (Universal Serial Bus) memory, etc.) in an installable file format or an executable file format, and provided to the apparatus 4 via a dedicated reading medium.

[0056] The acquisition unit 420 acquires each synthesized signal (S12, S34) after signal processing over time. The specific operation of the acquisition unit 420 will be described later.

[0057] The spectrum generation unit 421 executes FFT processing on the signal (synthesized signal (S12, S34)) acquired by the acquisition unit 420 to generate a monitoring spectrum. The specific operation of the spectrum generation unit 421 will be described later.

[0058] The "monitoring spectrum" indicates the intensity of each frequency component included in each synthesized signal (S12, S34). The monitoring spectrum includes a fundamental wave component, a high-frequency component, and a vibration component corresponding to the monitoring target (for example, a rotation frequency, etc.). The frequency resolution of the monitoring spectrum is appropriately changed by the spectrum generation unit 421 according to the monitoring target. That is, the resolution is appropriately set according to the monitoring target. By making the resolution of the monitoring spectrum variable in this way, for example, the resolution of the monitoring target for which it is desired to determine the positional deviation of the position (frequency) of the monitoring peak (described later) is set to a high resolution, and the resolution of the monitoring target for which such determination is not required is set to a low resolution, etc., so that the resolution can be used appropriately. As a result, the computational load is minimized, and the memory usage can be reduced. In the present embodiment, the monitoring spectrum includes a first monitoring spectrum generated based on the synthesized signal (S12) and a second monitoring spectrum generated based on the synthesized signal (S34).

[0059] FIG. 6(a) is a frequency characteristic diagram showing an example of the monitoring spectrum generated by the present apparatus 4, and (b) is a frequency characteristic diagram showing an example of a spectrum serving as a comparative example (hereinafter referred to as "comparative spectrum"). FIG. (a) shows the first monitoring spectrum. FIG. (b) shows the comparative spectrum obtained by executing FFT processing on the signal of the acceleration sensor attached to the pump 1.

[0060] As shown in FIG. 6(a), in the monitoring spectrum, the peak of the driving frequency (hereinafter referred to as "power peak") appears strongly. In particular, the power peaks of odd harmonics appear strongly, and the intensity of the power peaks of even harmonics is less than or equal to half of the intensity of the power peaks of odd harmonics. Also, as shown in FIGS. 6(a) and 6(b), in the monitoring spectrum, the power peaks of odd harmonics of the 11th order or higher also have sufficient intensity. On the other hand, in the comparison spectrum, the harmonics of the 11th order or higher are attenuated and do not have an extractable intensity. Also, there is no tendency in the intensity of the power peaks of odd and even harmonics. The phenomenon appearing in the monitoring spectrum is due to the fact that the monitoring spectrum is the combined signal of the two detection coils C1 and C2. In FIG. 6(a), "fb1" indicates the monitoring peak of the 7th harmonic of the rotation frequency of the rolling element 31c, and "fb2" indicates the monitoring peak of the 7th harmonic of the rotation frequency of the rolling element 32c. On the other hand, in FIG. 6(b), the monitoring peaks corresponding to "fb1" and "fb2" do not appear. Thus, in the monitoring spectrum, higher-order monitoring peaks with extractable intensity also appear, but in the comparison spectrum, the same monitoring peaks do not appear. In this device 4, by using the monitoring spectrum, it becomes possible to monitor the state of the monitoring target using higher-order harmonic monitoring peaks that cannot be realized by an acceleration sensor.

[0061] Here, most of the positions of the monitoring peaks appearing in the first monitoring spectrum are common to the positions of the monitoring peaks appearing in the second monitoring spectrum. However, the inventor of the present invention has discovered that some monitoring peaks appear only in either the first monitoring spectrum or the second monitoring spectrum. Also, the inventor of the present invention has discovered that the intensities of the monitoring peaks common to the first monitoring spectrum and the second monitoring spectrum are different. This is presumably due to the different methods of combining the combined signal (S12) and the combined signal (S34). This device 4 can monitor more various states of the monitoring target by using two types of combined signals (S12, S34).

[0062] In the following description, FIGS. 1 and 2 are mainly referred to. The first calculation unit 422 calculates a theoretical monitoring frequency band for each monitoring target based on parameters set based on the specifications of the monitoring target. A specific operation of the first calculation unit 422 will be described later. The first calculation unit 422 is an example of a theoretical frequency band calculation unit in the present invention.

[0063] The "parameters" are numerical values ​​included in the specifications of the monitored object, and are numerical values ​​required for calculating the theoretical monitoring frequency. For example, when the monitored object is the bearings 31, 32, the parameters are the outer diameter of the inner rings 31a, 32a, the inner diameter of the outer rings 31b, 32b, and the diameter, number, contact angle, and rotation frequency of the rolling elements 31c, 32c (or the rotation frequency of the rotating shaft 30). When the monitored object is the impellers 51, 52, the parameters are the number of blades, the rotation frequency, and the like. The parameters are set (input) in advance in the device 4, for example, before shipment of the pump 1, and are stored in the memory unit 43.

[0064] The "theoretical monitoring frequency" is a theoretical frequency indicating a periodic displacement of the position of the monitoring object. The theoretical monitoring frequency is, for example, the vibration frequency of the monitoring object when the rotor 33 rotates at a set rotation speed (described later). The theoretical monitoring frequency is calculated, for example, by inputting parameters into a known calculation formula. That is, for example, when the monitoring object is the bearing 31, the theoretical monitoring frequency is the inner ring rolling element passing frequency (inner ring pulse generating frequency), the outer ring rolling element passing frequency (outer ring pulse generating frequency), the rolling element rotation frequency, or the rolling element revolution frequency. When the monitoring object is a part of the bearing 31 (for example, the contact surface between the inner ring 31a and the rolling element 31c), the theoretical monitoring frequency is a frequency corresponding to that part (for example, the inner ring rolling element passing frequency). Also, for example, when the monitoring object is the impellers 51 and 52, the theoretical monitoring frequency is the rotation frequency of the impellers 51 and 52.

[0065] The "theoretical monitoring frequency band" is a predetermined range of frequency bands including the theoretical monitoring frequency. The theoretical monitoring frequency band is set, for example, in a range of ± several Hz (for example, ± 5 Hz) centered on the theoretical monitoring frequency. The theoretical monitoring frequency bands correspond to the monitoring targets, and the number of the theoretical monitoring frequency bands is, for example, equal to or greater than the number of the monitoring targets.

[0066] The second calculation unit 423 calculates a correction value based on the set rotation speed and the measured rotation speed of the rotor 33. The specific operation of the second calculation unit 423 will be described later. The second calculation unit 423 is an example of the correction value calculation unit in the present invention.

[0067] The "set rotation speed" is, for example, the rotation speed of the pump 1 set in the pump 1 (that is, the rotation speed of the rotor 33). The set rotation speed is, for example, preset based on the drive frequency and is stored, for example, in the storage unit 43.

[0068] The "measured rotation speed" is the rotation speed of the pump 1 (that is, the rotation speed of the rotor 33) measured when the pump 1 is actually operating (when the rotor 33 is rotating). Generally, in a pump 1 that operates by electromagnetic force, a phenomenon called "slip" occurs, where a speed difference occurs between the speed of the rotating magnetic field and the speed of the rotor 33. This "slip" increases as the rotation speed and load of the rotor 33 increase. When "slip" occurs, the measured rotation speed becomes smaller than the set rotation speed.

[0069] The "correction value" is a coefficient for correcting the theoretical monitoring frequency band to the actual monitoring frequency band in the pump 1 where "slip" occurs. The theoretical monitoring frequency is calculated on the premise that the rotor 33 is rotating at the set rotational speed. Therefore, when the rotor 33 is rotating at the measured rotational speed, the actual monitoring frequency is slightly lower than the theoretical monitoring frequency due to the influence of "slip". Therefore, in order to accurately monitor the state of the monitoring target when the pump 1 is operating (when "slip" occurs), correction is required to adjust the theoretical monitoring frequency to the actual monitoring frequency. The correction value is, for example, the ratio of the set rotational speed to the measured rotational speed. In the present embodiment, the correction value is the ratio of the rotor rotation component frequency determined by the set rotational speed (the calculated harmonic component: hereinafter referred to as "theoretical rotation component") to the rotor rotation component frequency determined by the measured rotational speed (the measured harmonic component: hereinafter referred to as "measured rotation component"). In other words, the measured rotation component is the rotor rotation component frequency when "slip" occurs. The monitoring spectrum includes harmonic components (rotor rotation components). Therefore, the present apparatus 4 can calculate the correction value by acquiring the frequency of the harmonic component (rotor rotation component frequency) when "slip" occurs based on the monitoring spectrum.

[0070] The correction unit 424 corrects the theoretical monitoring frequency band with the correction value to calculate the monitoring frequency band. The specific operation of the correction unit 424 will be described later.

[0071] The "monitoring frequency band" is a frequency band within a predetermined range including the actual monitoring frequency considering "slip". The monitoring frequency band is set, for example, in the range of ± several Hz centered on the monitoring frequency. The number of monitoring frequency bands is the same as the number of theoretical monitoring frequency bands.

[0072] As described above, the detection signals of the detection coils C1 to C4 include fundamental wave components. Also, in the pump 1, one rotating shaft 30 serves as both the motor shaft and the pump shaft. That is, in the pump 1, the configuration of the pump and the configuration of the motor are integrated. Therefore, the drive frequency of the drive power source appears strongly in the monitoring spectrum generated based on the detection signal. In the monitoring spectrum, the intensity of the peak of the monitoring frequency (hereinafter referred to as "monitoring peak") is weaker than the intensity of the peak of the drive frequency (hereinafter referred to as "power source peak"). Therefore, if the fundamental wave frequency of the monitoring peak is located within a predetermined frequency range centered on the fundamental wave frequency of the power source peak, the monitoring peak will be included in the power source peak. In this case, when the frequency resolution is set very high, the monitoring peak can be distinguished (extracted) from the source peak. However, as the frequency resolution is set higher, the processing time and load such as FFT analysis can increase. On the other hand, when the frequency resolution is set low, the monitoring peak cannot be distinguished (extracted) from the power source peak. Here, the interval (frequency) between the monitoring peak and the power source peak at the fundamental wave frequency increases in proportion to the order of the harmonic. Therefore, when the frequency resolution is set low, the monitoring frequency band of such a monitoring target may be set to a frequency band centered on (including) higher-order harmonics such that the interval becomes larger until the monitoring peak can be distinguished. That is, the monitoring frequency band is set based on the peak of the spectrum of the nth-order (n is an integer of 3 or more) harmonic of the monitoring peak, where the nth-order harmonic frequency of the monitoring peak is located outside the predetermined frequency range centered on the nth-order harmonic frequency of the power source peak. That is, for example, when the predetermined frequency range is "±b" Hz and the interval between the power source peak and the monitoring peak at the fundamental wave frequency is "a" Hz (a < b), the monitoring frequency band is exceptionally set to include the nth-order harmonic frequency that satisfies the relationship of "n × a > b".

[0073] FIG. 7 is a schematic diagram showing an exceptional monitoring frequency band used in the present apparatus 4. This figure shows that by satisfying the relationship of "n × a > b", at the nth-order harmonic frequency, the monitoring peak is separated from the power source peak and can be easily distinguished.

[0074] In the following description, Figure 2 is mainly referred to. The determination unit 425 determines whether the state of the monitoring target corresponding to the monitoring frequency band is normal or abnormal based on the comparison between the monitoring spectrum and the reference spectrum in the monitoring frequency band. The specific operation of the determination unit 425 will be described later.

[0075] The "reference spectrum" is a spectrum to be compared with the monitoring spectrum. The reference spectrum is, for example, any one of the monitoring spectra generated over time by the present apparatus 4 (spectrum generation unit 421). In the present embodiment, the reference spectrum is a monitoring spectrum generated when the state of the monitoring target is normal. The reference spectrum includes a first reference spectrum that is a comparison target for the first monitoring spectrum and a second reference spectrum that is a comparison target for the second monitoring spectrum.

[0076] The "determination based on comparison" is performed on at least one of the position, intensity, or shape of the monitoring peak.

[0077] The display control unit 426 controls the display of the display unit 44 based on the determination result of the determination unit 425. The specific operation of the display control unit 426 will be described later.

[0078] The storage unit 43 stores information necessary for the operation of the present apparatus 4 (for example, theoretical monitoring frequency band, monitoring frequency band, correction value, reference spectrum, etc.). The storage unit 43 is, for example, a non-volatile memory such as an EEPROM (Electrically Erasable Programmable Read-Only Memory) or a flash memory.

[0079] Figure 8 is a schematic diagram showing an example of the information (theoretical monitoring frequency band, monitoring frequency band) stored in the storage unit 43. The figure shows that the storage unit 43 stores a plurality of theoretical monitoring frequency bands and monitoring frequency bands. The figure shows, for example, that the theoretical monitoring frequency of the monitoring target "A" is "A2", and the theoretical monitoring frequency band of the monitoring target "A" is from "A1" to "A3".

[0080] Figure 9 is a schematic diagram showing an example of other information (correction value) stored in the storage unit 43. The figure shows that the theoretical rotation component is "X", the measured rotation component is "Y", and the correction value is "Z". The correction value "Z" is, for example, "Y / X".

[0081] In the following description, Figure 2 is mainly referred to. The display unit 44 displays the state of the monitoring target. The display unit 44 displays the state as "green (normal)" and "red (abnormal)" for each monitoring target, for example.

[0082] ● Operation of the pump Next, the operation of the pump 1 will be described below centering on the operation of the present device 4. In the following description, Figures 1 and 2 are referred to as appropriate.

[0083] Figure 10 is a flowchart showing an example of the operation of the present device 4.

[0084] The present device 4 executes an initial adjustment process (ST1), and then executes a state monitoring process (ST2).

[0085] ● Initial adjustment process Figure 11 is a flowchart showing an example of the initial adjustment process (ST1).

[0086] The "Initial Adjustment Process (ST1)" is a process executed to calculate the monitoring frequency band before the execution of the state monitoring process (ST2). The initial adjustment process (ST1) is executed, for example, before the shipment of the pump 1 or after the maintenance of the pump 1. That is, the initial adjustment process (ST1) is executed when the monitoring target is in a normal state. By executing the initial adjustment process (ST1) by the present device 4, the present device 4 can monitor the state of the monitoring target based on the monitoring frequency band corresponding to "slip". The initial adjustment process (ST1) is an example of the present setting method.

[0087] First, the acquisition unit 420 acquires each parameter of the monitoring target (ST11: Parameter Acquisition Step). As described above, the parameters are set in the present device 4 in advance and stored in the storage unit 43.

[0088] Next, the first calculation unit 422 calculates the theoretical monitoring frequency band for each monitoring target (ST12: First Calculation Step). As described above, the theoretical monitoring frequency is calculated based on the parameters and a known calculation formula. The first calculation unit 422 calculates a frequency band within a predetermined range centered on the calculated theoretical monitoring frequency as the theoretical monitoring frequency band. The calculated theoretical monitoring frequency band is stored in the storage unit 43, for example, in association with the monitoring target. At this time, the first calculation unit 422 also calculates a theoretical monitoring frequency band including the rotor rotation component frequency. The first calculation step is an example of the theoretical monitoring frequency band calculation step in the present invention.

[0089] Next, when the operation of the pump 1 is started, the acquisition unit 420 acquires the composite signals (S12, S34) when the pump 1 is operating (that is, when "slip" occurs) (ST13: Signal Acquisition Step). This acquisition is executed at a predetermined sampling frequency. The sampling frequency is set to be at least twice the rotor rotation component frequency (for example, 5 kHz). During the operation of the pump 1, a driving power supply is supplied to the motor unit 3, and the rotor 33, the rotating shaft 30, and the impellers 51, 52 are rotating at a predetermined rotational speed (measured rotational speed).

[0090] Next, the spectrum generation unit 421 executes FFT processing on the composite signal (S12) acquired by the acquisition unit 420 to generate a first monitoring spectrum, and executes FFT processing on the composite signal (S34) acquired by the acquisition unit 420 to generate a second monitoring spectrum (ST14: reference spectrum generation step). The first monitoring spectrum is stored in the storage unit 43 as a first reference spectrum, and the second monitoring spectrum is stored in the storage unit 43 as a second reference spectrum. In other words, the first reference spectrum and the second reference spectrum are the monitoring spectra acquired (initially) when the state of the monitoring target is normal among the monitoring spectra acquired over time.

[0091] Next, the second calculation unit 423 acquires the rotor rotation component frequency (i.e., the measured rotation component) based on at least one of the first reference spectrum and the second reference spectrum (ST15: rotation component acquisition step). As described above, the set rotation component can be calculated based on the drive frequency and the number of rotor bars 33a. The second calculation unit 423 acquires, for example, the frequency of the peak closest to the set rotation component as the measured rotation component in the theoretical monitoring frequency band centered on the calculated set rotation component.

[0092] Next, the second calculation unit 423 calculates a correction value based on the set rotation component and the measured rotation component (ST16: second calculation step). As described above, the correction value is the ratio of the set rotation component to the measured rotation component. The set rotation component is proportional to the set drive frequency, i.e., the set rotation speed. The measured rotation component is proportional to the actual drive frequency, i.e., the measured rotation speed. Therefore, the correction value is also the ratio of the set rotation speed to the measured rotation speed. The correction value is stored in the storage unit 43 in association with the set rotation component and the measured rotation component, for example. The second calculation step is an example of the correction value calculation step in the present invention.

[0093] Next, the correction unit 424 corrects the theoretical monitoring frequency band with the correction value to calculate the monitoring frequency band (ST17: correction step). The correction unit 424 calculates the monitoring frequency band corresponding to the theoretical monitoring frequency band, for example, by multiplying the theoretical monitoring frequency band by the correction value. The monitoring frequency band is associated with the monitoring target and stored in the storage unit 43.

[0094] ● State monitoring process FIG. 12 is a flowchart showing an example of the state monitoring process (ST2).

[0095] The "state monitoring process (ST2)" is a process for monitoring the state of the monitoring target during the operation of the pump 1. The state monitoring process (ST2) is an example of this monitoring method.

[0096] First, the acquisition unit 420 acquires each synthesized signal (S12, S34) after signal processing over time (ST21: signal acquisition step). Each synthesized signal (S12, S34) is acquired at a predetermined time interval (for example, once per hour).

[0097] Next, the spectrum generation unit 421 executes FFT processing on the synthesized signal (S12) acquired by the acquisition unit 420 to generate a first monitoring spectrum, and executes FFT processing on the synthesized signal (S34) acquired by the acquisition unit 420 to generate a second monitoring spectrum (ST22: monitoring spectrum generation step). The first monitoring spectrum and the second monitoring spectrum are stored in the storage unit 43.

[0098] FIG. 13(a) is a frequency characteristic diagram showing an example of the monitoring spectrum (second monitoring spectrum) generated by the present apparatus 4, and (b) is a frequency characteristic diagram showing an example of the comparison spectrum.

[0099] This figure shows that at the monitoring frequency (outer raceway passing frequency: about 128 Hz), the intensity of the peak of the second monitoring spectrum during abnormal times is higher than that during normal times. Also, this figure shows that the peak of the intensity of the second monitoring spectrum at the monitoring frequency varies in the same manner as the peak of the intensity of the comparison spectrum.

[0100] Next, the determination unit 425 acquires the spectrum of the monitoring frequency band (hereinafter referred to as the "individual monitoring spectrum") from the latest first monitoring spectrum and acquires the individual monitoring spectrum from the latest second monitoring spectrum (ST23). The individual monitoring spectrum is acquired for each monitoring target (monitoring frequency band).

[0101] Next, the determination unit 425 acquires the spectrum of the frequency band corresponding to the monitoring frequency band (hereinafter referred to as the "reference monitoring frequency band") from the first reference spectrum and acquires the individual reference monitoring spectrum from the second reference spectrum (ST24). The individual reference spectrum is acquired for each monitoring target (reference monitoring frequency band).

[0102] In the present invention, the individual reference spectrum may be acquired in advance and stored in the storage unit 43.

[0103] Next, the determination unit 425 compares the individual monitoring spectrum with the individual reference monitoring spectrum corresponding to the same individual monitoring spectrum for each monitoring target (monitoring frequency band) (ST25: comparison step). As described above, the comparison is performed for at least one of the intensity, position, or shape of the monitoring peak.

[0104] Next, the determination unit 425 compares the comparison result with a predetermined threshold value to determine, for example, whether the comparison result is within the predetermined threshold value (ST26: determination process). When the state of the monitoring target is abnormal, the intensity of the monitoring peak corresponding to the monitoring target fluctuates greatly. Therefore, when the amount of change in intensity is greater than the predetermined threshold value, the determination unit 425 can determine that "the state of the monitoring target is abnormal". Similarly, when the state of the monitoring target is abnormal, the position (frequency) of the monitoring peak corresponding to the monitoring target may vary. For example, when the monitoring targets are the rolling elements 31c and 32c, when a thrust load is applied to the rolling elements 31c and 32c, the contact angle of the rolling elements 31c and 32c changes, and the position of the monitoring peak fluctuates slightly. Therefore, when the amount of change in position is greater than the predetermined threshold value, the determination unit 425 can determine that "the state of the monitoring target is abnormal". Also, the FFT process is calculated using the average value over a specific period. Therefore, when "slip" changes continuously in response to addition, the shape of the monitoring peak (the shape of the spectrum) fluctuates (becomes dull). Here, the monitoring spectrum is a set of discrete values in units of resolution (for example, 1 Hz). Therefore, the shape of the monitoring peak can be recognized based on the magnitude relationship of the intensities before and after the monitoring peak. The determination unit 425 can recognize each shape as an area and compare them by calculating the integrated values of the individual monitoring spectrum and the individual reference monitoring spectrum. The predetermined threshold value is determined in advance and stored in the storage unit 43.

[0105] When the comparison result is within the predetermined threshold value ("Y" in ST26), the determination unit 425 determines that "the state of the monitoring target is normal", and the display control unit 426 causes the display unit 44 to display "normal" (ST27).

[0106] On the other hand, when the comparison result is greater than the predetermined threshold value ("N" in ST26), the determination unit 425 determines that "the state of the monitoring target is abnormal", and the display control unit 426 causes the display unit 44 to display "abnormal" (ST28).

[0107] ●Summary According to the embodiments described above, the present device 4 includes four detection coils C1 to C2, an acquisition unit 420, a spectrum generation unit 421, a determination unit 425, and a storage unit 43. The detection coils C1 to C4 include a pair of detection coils C1, C2 and a pair of detection coils C3, C4. The detection coils C1 and C2 are connected in series so that the difference between their detection signals can be obtained. The detection coils C3 and C4 are connected in series so that their detection signals are superimposed. The detection coils C1 to C4 are arranged at the same position in the thrust direction and at different positions in the circumferential direction. The detection coils C1 and C2 are arranged at positions different from those of the detection coils C3 and C4. The acquisition unit 420 acquires each composite signal (S12, S34) over time. The spectrum generation unit 421 performs FFT processing on the signals (each composite signal (S12, S34)) acquired by the acquisition unit 420 to generate a monitoring spectrum. The determination unit 425 determines whether the state of the monitoring target corresponding to the monitoring frequency band is normal or abnormal based on a comparison between the latest monitoring spectrum and the reference spectrum in the monitoring frequency band. The storage unit 43 stores the monitoring frequency band and the reference spectrum preset for the monitoring target. The monitoring spectrum includes a first monitoring spectrum and a second monitoring spectrum. The reference spectrum includes a first reference spectrum and a second reference spectrum. According to this configuration, the present device 4 can monitor the state of the monitoring target that appears as a periodic displacement of the position of the rotor 33 in the radial direction. Further, the monitoring spectrum is generated based on each composite signal (S12, S34). Therefore, higher-order harmonics that do not appear in the comparison spectrum also appear in the monitoring spectrum. Therefore, the present device 4 can realize state monitoring based on the monitoring peaks of higher-order harmonics that cannot be realized by an acceleration sensor by using the monitoring spectrum.

[0108] Also, according to the embodiments described above, the present apparatus 4 includes a first calculation unit 422, a second calculation unit 423, and a correction unit 424. According to this configuration, even if the theoretical monitoring frequency band is shifted from the actual monitoring frequency band due to "slip", the present apparatus 4 can monitor the state of the monitoring target by the monitoring frequency band with the correction by the correction value. In other words, the present apparatus 4 realizes the state monitoring of the monitoring target corresponding to "slip".

[0109] Furthermore, according to the embodiments described above, the acquisition unit 420 acquires a signal at a predetermined sampling frequency. The sampling frequency is set to be twice or more the rotor rotation component frequency. The second calculation unit 423 acquires a measured rotation component based on the monitoring spectrum, and calculates a correction value based on the set rotation component and the measured rotation component. According to this configuration, the present apparatus 4 can calculate the correction value easily and accurately.

[0110] Furthermore, according to the embodiments described above, the reference spectrum is the monitoring spectrum (first) acquired when the state of the monitoring target is normal among the monitoring spectra generated over time. The determination unit 425 determines the state based on at least one of the position, intensity, or shape of the monitoring peak in the monitoring frequency band. As described above, the monitoring target is a member whose state appears as a periodic displacement of the position of the rotor 33 in the radial direction. Therefore, the state of the monitoring target can be determined by the variation of the position, intensity, or shape of the monitoring peak. Therefore, the present apparatus 4 can easily monitor the state of the monitoring target by comparing the monitoring peaks.

[0111] Furthermore, according to the embodiments described above, the monitoring spectrum includes a power peak and a monitoring peak. When the fundamental frequency of the monitoring peak is within a predetermined frequency range centered on the fundamental frequency of the power peak, the monitoring frequency band of the object to be monitored is set based on the peak of the spectrum of the nth (n is an integer of 3 or more) harmonic frequency of the monitoring peak being outside the predetermined frequency range centered on the nth harmonic frequency of the power peak. According to this configuration, even if the monitoring peak is included in the power peak at the fundamental frequency, at the nth harmonic frequency, the monitoring peak is separated from the power peak and can be easily distinguished. As a result, the apparatus 4 can monitor the state of the object to be monitored even when the monitoring peak is included in the power peak at the fundamental frequency.

[0112] Furthermore, according to the embodiments described above, the apparatus 4 includes signal processing units 41a and 41b. The signal processing includes filter processing, absolute value processing, envelope processing, and differentiation processing. According to this configuration, in the monitoring spectrum, the monitoring peak is emphasized. Therefore, the monitoring accuracy of the state by the apparatus 4 is improved. Also, by performing differentiation processing according to the phenomenon to be monitored, the state of the object to be monitored can be monitored with higher accuracy.

[0113] Furthermore, according to the embodiments described above, the pump 1 includes a rotating shaft 30, bearings 31 and 32, a rotor 33, a stator 34, detection coils C1 to C4, and the apparatus 4. According to this configuration, the pump 1 can monitor the state of the object to be monitored by the apparatus 4.

[0114] ● Other Embodiments ● ● Detection Coils In the present invention, the number of the detection coils C1 to C4 is not limited to "4". That is, for example, the apparatus 4 may include only one of a set of detection coils C1 and C2 or a set of detection coils C3 and C4. Even with this configuration, the apparatus 4 can monitor the state of the object to be monitored based on the common monitoring peak.

[0115] Also, in the present invention, the apparatus 4 may be provided with only any one of the detection coils C1 to C4 (for example, the detection coil C1). In this case, in the initial adjustment process (ST1) and the state monitoring process (ST2), a detection signal is used instead of each composite signal (S12, S34). That is, the monitoring frequency band (theoretical monitoring frequency band, correction value) and the reference spectrum are set corresponding to the detection signal of the detection coil C1. The acquisition unit 420 acquires the detection signal of the detection coil C1 over time. The spectrum generation unit 421 executes FFT processing on the detection signal acquired by the acquisition unit 420 to generate a monitoring spectrum. The determination unit 425 determines whether the state of the monitoring target corresponding to the monitoring frequency band is normal or abnormal based on the comparison between the latest monitoring spectrum and the reference spectrum in the monitoring frequency band. In this configuration, it is difficult to monitor the state of some monitoring targets using the monitoring peaks of higher-order harmonics. However, the apparatus 4 can monitor the states of other monitoring targets excluding the monitoring target.

[0116] Furthermore, in the present invention, the positions of the detection coils C1 to C4 may be positions capable of detecting a magnetic flux change corresponding to the displacement of the position of the rotor 33 in the radial direction, and are not limited to the upper and lower ends of the stator 34. That is, for example, in the thrust direction, the detection coils C1 to C4 may be arranged at any position of the tooth portion 34c. Also, for example, the detection coils C3 and C4 may be arranged at the lower end of the tooth portion 34c.

[0117] Furthermore, in the present invention, the detection coils C1, C2 and the detection coils C3, C4 may not be connected in series. In this case, the apparatus 4 includes a synthesis circuit (for example, a subtraction circuit) that synthesizes the detection signals of the detection coils C1, C2 so that their difference can be obtained, and a synthesis circuit (for example, an addition circuit) that synthesizes the detection signals of the detection coils C3, C4 so that they are superimposed.

[0118] Furthermore, in the present invention, the configurations of the detection coils C1 to C4 may be different. That is, for example, the number of turns of the detection coils C1, C2 may be different from the number of turns of the detection coils C3, C4.

[0119] Furthermore, in the present invention, the detection coils C1 and C2 may be connected in series such that their detection signals are superimposed.

[0120] Furthermore, in the present invention, the detection coils C3 and C4 may be connected in series such that the difference between their detection signals is obtained.

[0121] ● Signal processing unit Furthermore, in the present invention, the apparatus 4 may not include the signal processing units 41a and 41b. In this case, the apparatus 4 includes an A / D conversion unit that converts each composite signal (S12, S34) into a digital signal. The acquisition unit 420 acquires each composite signal (S12, S34) converted into a digital signal.

[0122] Furthermore, in the present invention, the signal processing executed by the signal processing units 41a and 41b may be any processing capable of extracting a monitoring peak, and is not limited to the first filter processing, absolute value processing, second filter processing, envelope processing, differentiation processing, and A / D conversion processing.

[0123] Furthermore, in the present invention, the predetermined signal processing may be executed after A / D conversion.

[0124] Furthermore, in the present invention, the apparatus 4 may include only one of the signal processing unit 41a or the signal processing unit 41b.

[0125] ● Control unit Furthermore, in the present invention, the sampling frequency at which the acquisition unit 420 acquires a signal may be any frequency at which the second calculation unit 423 can acquire the rotor rotation component frequency.

[0126] Furthermore, in the present invention, the control unit 42 may not include the first calculation unit 422. In this configuration, the theoretical monitoring frequency is calculated in advance by an external device (for example, a computer) before the pump 1 is shipped and stored in the storage unit 43.

[0127] Furthermore, in the present invention, the control unit 42 may not include the second calculation unit 423 and the correction unit 424. In this configuration, the theoretical monitoring frequency band may be treated as the monitoring frequency band. The frequency range of this theoretical monitoring frequency band may be set relatively wide corresponding to "slip". Also, the monitoring frequency band may be calculated in advance by an external device before the pump 1 is shipped and stored in the storage unit 43.

[0128] Furthermore, in the present invention, the theoretical monitoring frequency band (monitoring frequency band) may be set in a range of ± several % centered on the theoretical monitoring frequency (monitoring frequency).

[0129] Furthermore, in the present invention, one monitoring frequency band may be set for one monitoring target, or a plurality of monitoring frequency bands may be set.

[0130] Furthermore, in the present invention, the correction value may be the ratio of the set rotation speed to the measured rotation speed, or the ratio of the drive frequency to the actually measured drive frequency.

[0131] Furthermore, in the present invention, the correction value may be updated at the timing when the monitoring spectrum is generated. In this case, the monitoring frequency band may be updated by the updated correction value. That is, the correction value may also be used in the state monitoring process (ST2).

[0132] Furthermore, in the present invention, when the numerator and denominator of the ratio of the correction values are reversed, the correction unit 424 may calculate the monitoring frequency band by dividing the theoretical monitoring frequency band by the correction value.

[0133] Furthermore, in the present invention, the reference spectrum may be any one of the monitoring spectra generated over time, and is not limited to the monitoring spectrum generated during the initial adjustment process (ST1).

[0134] Furthermore, in the present invention, the timing at which the reference spectrum is generated may be the timing at which the object to be monitored of the pump 1 is surely normal (for example, after the initial operation of the pump 1 or after the maintenance of the pump 1).

[0135] Furthermore, in the present invention, if a state other than normal and abnormal of the object to be monitored appears as a monitoring peak, the determination unit 425 may also determine the presence or absence of that state.

[0136] ● Pump Furthermore, in the present invention, the pump 1 may be any pump to which the detection coils C1 to C4 can be attached, and is not limited to a submerged pump.

[0137] Furthermore, in the present invention, the number of the impellers 51, 52 provided in the pump 1 is not limited to "2".

[0138] Furthermore, in the present invention, the bearings 31, 32 are not limited to rolling bearings.

[0139] ● Others Furthermore, in the present invention, the object to be monitored (content of abnormality) may be the rotor bar 33a (broken rotor bar 33a), the rotating shaft 30 (misalignment of the rotating shaft 30), or the motor unit 3 (insulation failure). Further, when the object to be monitored is the impellers 51, 52, the apparatus 4 may monitor the presence or absence of cavitation transmitted to the rotor 33 as the vibration of the impellers 51, 52 as the state of the impellers 51, 52.

[0140] Furthermore, in the present invention, the object to be monitored may be arbitrarily set according to the installation environment of the pump 1, and is not limited to the present embodiment. That is, for example, the object to be monitored may be only the rotating shaft 30 or only the displacement member.

[0141] ● Embodiments of the Present Invention ● Next, regarding the embodiments of the present invention grasped from the above-described embodiments, while referring to the terms and reference numerals described in each embodiment, the following will be described.

[0142] A first embodiment of the present invention is a state monitoring device (e.g., state monitoring device 4) that monitors the state of a monitoring target (e.g., rotating shaft 30, bearings 31, 32, rotor 33, impellers 51, 52) of a pump (e.g., pump 1) based on detection signals output from a plurality of detection coils (e.g., detection coils C1 to C4) that detect a magnetic flux change corresponding to a displacement of the position of a rotor (e.g., rotor 33) with respect to a stator (e.g., stator 34) of a motor (e.g., motor unit 3) of the pump. The plurality of detection coils are attached to the stator so as to be able to detect the magnetic flux change corresponding to the displacement in the radial direction of the rotor, and output a detection signal indicating the magnetic flux change. The state monitoring device includes a pair of the detection coils (e.g., detection coils C1, C2; detection coils C3, C4) whose detection signals are combined. Each of the pair of detection coils is arranged at the same position in the thrust direction of the rotor and at different positions in the circumferential direction of the rotor, and a first combined signal (e.g., combined signal (S12)) is combined so that the detection signals output from the pair of detection coils obtain a difference, and a second combined signal (e.g., combined signal (S34)) is combined so that the detection signals output from the pair of detection coils are superimposed. The state monitoring device has an acquisition unit (e.g., acquisition unit 420) that acquires at least one of them over time, a spectrum generation unit (e.g., spectrum generation unit 421) that executes FFT processing on the signal acquired by the acquisition unit to generate a monitoring spectrum, a storage unit (e.g., storage unit 43) that stores at least one monitoring frequency band preset for the monitoring target and a reference spectrum that is a comparison target of the monitoring spectrum, and a determination unit (e.g., determination unit 425) that determines whether the state of the monitoring target corresponding to the monitoring frequency band is normal or abnormal based on a comparison between the latest monitoring spectrum and the reference spectrum in the monitoring frequency band. According to this configuration, the present device can monitor the state of the monitoring target that appears as a periodic displacement of the position of the rotor in the radial direction.

[0143] The second embodiment of the present invention is as follows. In the first embodiment, a plurality of the detection coils include a pair of first detection coils (for example, detection coils C1 and C2) that function as a pair of the detection coils and output the detection signals that are the basis of the first composite signal, and a pair of second detection coils (for example, detection coils C3 and C4) that function as a pair of the detection coils and output the detection signals that are the basis of the second composite signal. The first detection coils are arranged at positions different from those of the second detection coils. The acquisition unit acquires the first composite signal and the second composite signal over time. The monitoring spectrum includes a first monitoring spectrum generated by performing the FFT process on the first composite signal and a second monitoring spectrum generated by performing the FFT process on the second composite signal. The reference spectrum includes a first reference spectrum that is a comparison target for the first monitoring spectrum and a second reference spectrum that is a comparison target for the second monitoring spectrum. It is a state monitoring device. According to this configuration, the present device can monitor the states of more types of monitoring targets by using two types of composite signals.

[0144] The third embodiment of the present invention is as follows. In the first or second embodiment, a theoretical monitoring frequency band calculation unit (for example, the first calculation unit 422) that calculates a theoretical monitoring frequency band for each monitoring target based on a parameter set based on the specifications of the monitoring target, a correction value calculation unit (for example, the second calculation unit 423) that calculates a correction value based on the set rotation speed of the rotor set for the pump and the measured rotation speed of the rotor measured when the pump is operating, and a correction unit (for example, the correction unit 424) that corrects the theoretical monitoring frequency band with the correction value to calculate the monitoring frequency band. It is a state monitoring device. According to this configuration, the present device realizes state monitoring of a monitoring target corresponding to "slip".

[0145] In a fourth embodiment of the present invention, in the third embodiment, the acquisition unit acquires the signal at a predetermined sampling frequency, and the sampling frequency is set to be at least twice the rotor rotation component frequency corresponding to a change in magnetic flux generated by the induced current flowing through the rotor bar (for example, rotor bar 33a) of the rotor. The correction value calculation unit acquires the rotor rotation component frequency determined by the measured rotation speed based on the monitoring spectrum, and calculates the correction value based on the theoretically determined rotor rotation component frequency determined by the set rotation speed and the rotor rotation component frequency determined by the measured rotation speed. This is a state monitoring device. According to this configuration, the present device can easily and accurately calculate the correction value.

[0146] In a fifth embodiment of the present invention, in the first embodiment, the reference spectrum is any one of the monitoring spectra generated over time, and the determination unit determines the state based on at least one of the position, intensity, or shape of the peak spectrum in the monitoring frequency band. This is a state monitoring device. According to this configuration, the present device can easily monitor the state of the monitoring target by comparing the monitoring peaks.

[0147] In a sixth embodiment of the present invention, in the first embodiment, the monitoring spectrum includes a power supply peak indicating the driving frequency of the driving power supply of the pump and a monitoring peak indicating the monitoring frequency determined for each monitoring target. When the fundamental wave frequency of the monitoring peak is located within a predetermined frequency range centered on the fundamental wave frequency of the power supply peak, the monitoring frequency band of the monitoring target is set based on the peak of the spectrum of the nth (n is an integer of 3 or more) harmonic frequency of the monitoring peak being located outside the predetermined frequency range centered on the nth harmonic frequency of the power supply peak. This is a state monitoring device. According to this configuration, the present device can monitor the state even for a monitoring target in which the monitoring peak is included in the power supply peak at the fundamental wave frequency.

[0148] The seventh embodiment of the present invention is, in the first embodiment, the monitoring target includes the rotating shaft of the motor (for example, the rotating shaft 30) and / or a displacement member (for example, the rotor 33, bearings 31, 32, impellers 51, 52) that abuts against the rotating shaft and whose position is periodically displaced in response to the rotation of the rotating shaft, and is a state monitoring device. According to this configuration, the present device can monitor the states of the rotating shaft, rotor, bearings, and impellers.

[0149] The eighth embodiment of the present invention is, in the first embodiment, a state monitoring device having a signal processing unit (for example, signal processing units 41a, 41b) that executes predetermined signal processing on at least one of the first composite signal and the second composite signal, and the acquisition unit acquires at least one of the first composite signal after the signal processing and the second composite signal after the signal processing over time. According to this configuration, the monitoring accuracy of the state by the present device is improved.

[0150] The ninth embodiment of the present invention is, in the eighth embodiment, a state monitoring device in which the signal processing includes filter processing, absolute value conversion processing, envelope processing, and differential processing. According to this configuration, the monitoring accuracy of the state by the present device is improved.

[0151] The tenth embodiment of the present invention is a state monitoring device (e.g., state monitoring device 4) for monitoring the state of a monitoring target (e.g., rotating shaft 30, bearings 31, 32, rotor 33, impellers 51, 52) of the pump based on a detection signal output from at least one detection coil (e.g., detection coil C1) that detects a magnetic flux change corresponding to a displacement of the position of a rotor (e.g., rotor 33) with respect to a stator (e.g., stator 34) of a motor (e.g., motor section 3) of the pump. The detection coil is attached to the stator so as to be able to detect the magnetic flux change corresponding to the displacement in the radial direction of the rotor, outputs the detection signal indicating the magnetic flux change, and an acquisition unit (e.g., acquisition unit 420) that acquires the detection signal over time, a spectrum generation unit (e.g., spectrum generation unit 421) that executes FFT processing on the detection signal acquired by the acquisition unit to generate a monitoring spectrum, a storage unit (e.g., storage unit 43) that stores at least one monitoring frequency band preset for the monitoring target and a reference spectrum that is a comparison target of the monitoring spectrum, and a determination unit (e.g., determination unit 425) that determines whether the state of the monitoring target corresponding to the monitoring frequency band is normal or abnormal based on a comparison between the latest monitoring spectrum and the reference spectrum in the monitoring frequency band. According to this configuration, the present device can monitor the state of the monitoring target that appears as a periodic displacement of the position of the rotor in the radial direction.

[0152] The eleventh embodiment of the present invention is a pump (e.g., pump 1) comprising a motor including a rotor (e.g., rotor 33), a stator (e.g., stator 34) that rotates the rotor, and a rotating shaft (e.g., rotating shaft 30) that rotates together with the rotor, bearings (e.g., bearings 31, 32) that support the rotating shaft, at least one detection coil (e.g., detection coils C1 to C4) that detects a magnetic flux change corresponding to a displacement of the position of the rotor with respect to the stator, and the state monitoring device (e.g., state monitoring device 4) according to claim 1 or 10 that monitors the state of a monitoring target of the pump based on a detection signal of the detection coil. According to this configuration, the pump can monitor the state to be monitored by this device.

[0153] A twelfth embodiment of the present invention is a state monitoring program that causes a computer to function as the state monitoring device described in the first or tenth embodiment. According to this configuration, the computer functions as the state monitoring device according to the present invention.

[0154] A 13th embodiment of the present invention is a state monitoring method (e.g., state monitoring process (ST2)) executed by a state monitoring device (e.g., state monitoring device 4) that monitors the state of a monitoring target (e.g., rotating shaft 30, bearings 31, 32, rotor 33, impellers 51, 52) of a pump (e.g., pump 1) based on detection signals output from a plurality of detection coils (e.g., detection coils C1 to C4) that detect a change in magnetic flux corresponding to a displacement in the position of a rotor (e.g., rotor 33) with respect to a stator (e.g., stator 34) of a motor (e.g., motor unit 3) of the pump. The plurality of detection coils are attached to the stator so as to be able to detect the change in magnetic flux corresponding to the displacement in the radial direction of the rotor, output a detection signal indicating the change in magnetic flux, and include a pair of the detection coils (e.g., detection coils C1, C2, detection coils C3, C4) whose detection signals are combined. The state monitoring device includes a storage unit (e.g., storage unit 43) that stores at least one monitoring frequency band preset for the monitoring target and a reference spectrum. The state monitoring method includes a signal acquisition step (e.g., signal acquisition step (ST21)) in which the state monitoring device acquires at least one of a first combined signal (e.g., combined signal (S12)) obtained by combining the detection signals output from a pair of the detection coils so as to obtain a difference and a second combined signal (e.g., combined signal (S34)) obtained by combining the detection signals output from a pair of the detection coils so as to be superimposed, over time; a monitoring spectrum generation step (e.g., monitoring spectrum generation step (ST22)) in which the state monitoring device executes FFT processing on the signal acquired in the signal acquisition step to generate a monitoring spectrum; and a determination step (e.g., determination step (ST26)) in which the state monitoring device determines whether the state of the monitoring target corresponding to the monitoring frequency band is normal or abnormal based on a comparison between the latest monitoring spectrum and the reference spectrum in the monitoring frequency band. According to this configuration, the present device can monitor the state of the monitoring target that appears as a periodic displacement in the position of the rotor in the radial direction.

[0155] The 14th embodiment of the present invention is a frequency band setting method (for example, initial adjustment process (ST1)) for setting a monitoring frequency band of a monitoring target (for example, a rotating shaft 30, bearings 31, 32, a rotor 33, impellers 51, 52) of the pump, which is executed by a state monitoring device (for example, state monitoring device 4) that monitors the state of the monitoring target based on detection signals output from a plurality of detection coils (for example, detection coils C1 to C4) that detect a magnetic flux change corresponding to a displacement of the position of a rotor (for example, rotor 33) with respect to a stator (for example, stator 34) of a motor (for example, motor section 3) of the pump. The detection coils are attached to the stator so as to be able to detect the magnetic flux change corresponding to the displacement in the radial direction of the rotor, and output the detection signal indicating the magnetic flux change. The frequency band setting method includes: a parameter acquisition step (for example, parameter acquisition step (ST11)) in which the state monitoring device acquires a parameter based on the specifications of the monitoring target; a theoretical monitoring frequency band calculation step (for example, first calculation step (ST12)) in which the state monitoring device calculates a theoretical monitoring frequency band for each monitoring target based on the parameter; a rotation component acquisition step (for example, rotation component acquisition step (ST15)) in which the state monitoring device acquires a rotor rotation component frequency determined by the measured rotation speed of the rotor measured when the pump is operating; a correction value calculation step (for example, second calculation step (ST16)) in which the state monitoring device calculates a correction value based on the rotor rotation component frequency determined by the set rotation speed of the rotor set in the pump and the rotor rotation component frequency determined by the measured rotation speed; and a correction step (for example, correction step (ST17)) in which the state monitoring device corrects the theoretical monitoring frequency band with the correction value to calculate the monitoring frequency band. According to this configuration, the present device realizes state monitoring of the monitoring target corresponding to "sliding".

Explanation of Signs

[0156] 1 Pump 3 Motor section (motor) 30 Rotating shaft (monitoring target) 31 Bearing (object to be monitored, displacement member) 32 Bearing (object to be monitored, displacement member) 33 Rotor (object to be monitored, displacement member) 34 Stator 4 Condition monitoring device 41a Signal processing unit 41b Signal processing unit 420 Acquisition unit 421 Spectrum generation unit 422 First calculation unit (theoretical monitoring frequency band calculation unit) 423 Second calculation unit (correction value calculation unit) 424 Correction unit 425 Judgment unit 43 Memory unit 51 Impeller (object to be monitored, displacement member) 52 Impeller (object to be monitored, displacement member) C1 Detection coil (first detection coil) C2 Detection coil (first detection coil) C3 Detection coil (second detection coil) C4 Detection coil (second detection coil)

Claims

1. 1. A status monitoring device that monitors a status of a pump based on detection signals output from a plurality of detection coils that detect magnetic flux changes corresponding to a displacement of a rotor position relative to a stator of a motor of the pump, comprising: The plurality of detection coils include a magnetic flux change detecting means for detecting the change in magnetic flux corresponding to the radial displacement of the rotor; outputting the detection signal indicative of the change in magnetic flux; A pair of the detection coils whose detection signals are combined; Including, The pair of detection coils are disposed at the same position in a thrust direction of the rotor and at different positions in a circumferential direction of the rotor, an acquisition unit that acquires, over time, at least one of a first composite signal obtained by combining the detection signals output from the pair of detection coils to obtain a difference, and a second composite signal obtained by combining the detection signals output from the pair of detection coils to be superimposed; a spectrum generating unit that performs an FFT process on the signal acquired by the acquiring unit to generate a monitoring spectrum; a storage unit that stores at least one monitoring frequency band that is preset for the monitoring target and a reference spectrum that is to be compared with the monitoring spectrum; a determination unit that determines whether the state of the monitoring target corresponding to the monitoring frequency band is normal or abnormal based on a comparison between the latest monitoring spectrum and the reference spectrum in the monitoring frequency band; It is made of Condition monitoring device.

2. The plurality of detection coils include a pair of first detection coils functioning as the pair of detection coils and outputting the detection signal on which the first composite signal is based; a pair of second detection coils that function as the pair of detection coils and output the detection signal that is the basis of the second composite signal; Including, The first detection coil is disposed at a position different from that of the second detection coil, The acquisition unit acquires the first composite signal and the second composite signal over time, The monitoring spectrum is a first monitoring spectrum generated by performing the FFT process on the first composite signal; a second monitoring spectrum generated by performing the FFT process on the second composite signal; and Including, The reference spectrum is a first reference spectrum to be compared with the first monitoring spectrum; a second reference spectrum to be compared with the second monitoring spectrum; Including, The condition monitoring device according to claim 1 .

3. a theoretical monitoring frequency band calculation unit that calculates a theoretical monitoring frequency band for each of the monitoring targets based on parameters set based on the specifications of the monitoring targets; a correction value calculation unit that calculates a correction value based on a set rotation speed of the rotor that is set in the pump and a measured rotation speed of the rotor that is measured while the pump is operating; a correction unit that corrects the theoretical monitoring frequency band with the correction value to calculate the monitoring frequency band; It is made of The condition monitoring device according to claim 1 or 2.

4. The acquisition unit acquires the signal at a predetermined sampling frequency, the sampling frequency is set to be equal to or greater than twice the frequency of a rotor rotation component corresponding to a change in magnetic flux generated by an induced current flowing through a rotor bar of the rotor, The correction value calculation unit acquiring the rotor rotation component frequency determined by the measured rotation speed based on the monitoring spectrum; calculating the correction value based on the theoretical rotor rotation component frequency determined by the set rotation speed and the rotor rotation component frequency determined by the measured rotation speed; The condition monitoring device according to claim 3.

5. the reference spectrum is any one of the monitoring spectra generated over time, The determination unit determines the state based on at least one of a position, an intensity, and a shape of a peak spectrum in the monitored frequency band. The condition monitoring device according to claim 1 .

6. The monitoring spectrum is A power supply peak indicating a drive frequency of a drive power supply for the pump; A monitoring peak indicating a monitoring frequency determined for each of the monitoring objects; Including, When the fundamental frequency of the monitoring peak is located within a predetermined frequency range centered on the fundamental frequency of the power supply peak, the monitoring frequency band of the monitoring target is set based on a peak of an n-th order harmonic spectrum in which an n-th order (n is an integer of 3 or more) harmonic frequency of the monitoring peak is located outside the predetermined frequency range centered on the n-th order harmonic frequency of the power supply peak. The condition monitoring device according to claim 1 .

7. The monitoring target is: A rotating shaft of the motor, and / or a displacement member that contacts the rotation shaft and whose position is periodically displaced in response to rotation of the rotation shaft; Including, The condition monitoring device according to claim 1 .

8. a signal processing unit that performs predetermined signal processing on at least one of the first composite signal and the second composite signal; and The acquisition unit acquires, over time, at least one of the first combined signal after the signal processing and the second combined signal after the signal processing. The condition monitoring device according to claim 1 .

9. The signal processing includes a filter process, an absolute value process, an envelope process, and a differentiation process. The condition monitoring device according to claim 8.

10. 1. A status monitoring device for monitoring a status of a pump based on a detection signal output from only one detection coil that detects a magnetic flux change corresponding to a displacement of a rotor position relative to a stator of a motor of the pump, comprising: The detection coil is a magnetic flux change detecting means for detecting the change in magnetic flux corresponding to the radial displacement of the rotor; outputting the detection signal indicative of the change in magnetic flux; An acquisition unit that acquires the detection signal over time; a spectrum generating unit that performs an FFT process on the detection signal acquired by the acquiring unit to generate a monitoring spectrum; a storage unit that stores at least one monitoring frequency band that is preset for the monitoring target and a reference spectrum that is to be compared with the monitoring spectrum; a determination unit that determines whether the state of the monitoring target corresponding to the monitoring frequency band is normal or abnormal based on a comparison between the latest monitoring spectrum and the reference spectrum in the monitoring frequency band; It is made of Condition monitoring device.

11. A motor including a rotor, a stator that rotates the rotor, and a rotating shaft that rotates together with the rotor; A bearing for supporting the rotating shaft; at least one sensing coil for detecting magnetic flux changes corresponding to displacement of the rotor relative to the stator; The state monitoring device according to claim 1 or 10, which monitors a state of a monitoring target of the pump based on a detection signal of the detection coil; It is made of pump.

12. A computer is caused to function as the condition monitoring device according to claim 1 or 10. Condition monitoring program.

13. 1. A condition monitoring method executed by a condition monitoring device that monitors a condition of a monitored object of a pump based on detection signals output from a plurality of detection coils that detect magnetic flux changes corresponding to a displacement of a position of a rotor relative to a stator of a motor of the pump, the method comprising: The plurality of detection coils include a magnetic flux change detecting means for detecting the change in magnetic flux corresponding to the radial displacement of the rotor; outputting the detection signal indicative of the change in magnetic flux; a pair of the detection coils whose detection signals are combined; Including, The condition monitoring device includes: a storage unit that stores at least one monitoring frequency band that is preset for the monitoring target and a reference spectrum; With The condition monitoring method includes: a signal acquisition step in which the state monitoring device acquires, over time, at least one of a first composite signal obtained by combining the detection signals output from the pair of detection coils to obtain a difference, and a second composite signal obtained by combining the detection signals output from the pair of detection coils to be superimposed; a monitoring spectrum generating step in which the state monitoring device performs an FFT process on the signal acquired in the signal acquiring step to generate a monitoring spectrum; a determination step in which the state monitoring device determines whether the state of the monitored object corresponding to the monitoring frequency band is normal or abnormal based on a comparison between the latest monitoring spectrum and the reference spectrum in the monitoring frequency band; Including, Condition monitoring methods.

Images