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

Abstract

The present invention monitors the state of a monitored portion of a pump, the state appearing as periodic displacement of a rotor position.　A state monitoring device 4 according to the present invention monitors the state of a monitored portion of a pump 1 on the basis of detection signals output from a plurality of detection coils C1-C4 that detect magnetic flux changes corresponding to displacement of the position of a rotor 33 relative to a stator 34 of a motor 3 of the pump. The state monitoring device 4 comprises: 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 performs FFT processing on the signal acquired by the acquisition unit to generate a monitored spectrum; a storage unit 43 that stores a monitored frequency band that is preset for the monitored portion and a reference spectrum to be compared with the monitored spectrum; and a determination unit 425 that determines whether the state of the monitored portion corresponding to the monitored frequency band is normal or abnormal on the basis of comparison between the latest monitored spectrum and the reference spectrum in the monitored frequency band.

Description

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

[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.

[0002] Pumps are used for relatively long periods to pump liquids in factories, plants, etc. Therefore, load is applied to the components of the pump, especially the rotating components (e.g., bearings), over a long period. 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).

[0003] Japanese Patent No. 7138817

[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 a 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 state monitoring device, a pump, a state monitoring program, a state monitoring method, and a frequency band setting method that can monitor the state of a pump monitoring target that appears as a periodic displacement of the position of the rotor.

[0006] A state monitoring device in one embodiment of the present invention monitors the state of a pump based on detection signals output from a plurality of detection coils that detect a change in magnetic flux corresponding to the displacement of the rotor position relative to the stator of the pump motor, wherein the plurality of detection coils include a pair of detection coils that are mounted on the stator so as to be able to detect the change in magnetic flux corresponding to the displacement of the rotor in the radial direction, and that output the detection signals indicating the change in magnetic flux, and the detection signals are synthesized, and 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 outputs from the pair of detection coils The system comprises: an acquisition unit that acquires at least one of a first combined signal, which is synthesized so as to obtain a difference between the detection signals, and a second combined signal, which is synthesized so as to superimpose the detection signals output from a pair of detection coils, over time; a spectrum generation unit that generates a monitoring spectrum by performing FFT processing on the signals acquired by the acquisition unit; a storage unit that stores at least one monitoring frequency band that is set in advance for the monitored object, and a reference spectrum that is used for comparison with the monitoring spectrum; and a determination unit that determines whether the state of the monitored object corresponding to the monitoring frequency band is normal or abnormal based on a comparison of the latest monitoring spectrum and the reference spectrum in the monitoring frequency band.

[0007] A state monitoring device in one embodiment of the present invention is a state monitoring device that monitors the state of a pump based on a detection signal output from only one detection coil that detects a change in magnetic flux corresponding to the displacement of the rotor position relative to the stator of the pump motor, wherein the detection coil is attached to the stator so as to be able to detect the change in magnetic flux corresponding to the displacement of the rotor in the radial direction, and the device includes an acquisition unit that outputs the detection signal indicating the change in magnetic flux and acquires the detection signal over time, a spectrum generation unit that performs 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 set in advance for the monitoring object and a reference spectrum to be compared with the monitoring spectrum, and a determination unit that determines whether the state of the monitoring object corresponding to the monitoring frequency band is normal or abnormal based on a comparison of the latest monitoring spectrum and the reference spectrum in the monitoring frequency band.

[0008] A pump in one embodiment of the present invention comprises a motor having 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 change in magnetic flux corresponding to the displacement of the rotor's position relative to the stator; and a state monitoring device according to each of the above embodiments that monitors the state of the object being monitored by the pump based on the detection signal from the detection coil.

[0009] The status monitoring program in one embodiment of the present invention causes a computer to function as a status monitoring device as described in each of the above embodiments.

[0010] A state monitoring method in one embodiment of the present invention is a state monitoring method performed by a state monitoring device that monitors the state of a pump based on detection signals output from a plurality of detection coils that detect a change in magnetic flux corresponding to the displacement of the rotor position relative to the stator of the pump motor, wherein the plurality of detection coils include a pair of detection coils that are mounted on the stator so as to be able to detect the change in magnetic flux corresponding to the displacement of the rotor in the radial direction and output the detection signals indicating the change in magnetic flux, and the detection signals are synthesized, and the state monitoring device includes a storage unit that stores at least one monitoring frequency band and a reference spectrum that are set in advance for the pump, and the state The state monitoring method includes: a signal acquisition step in which the state monitoring device acquires at least one of a first combined signal, which is obtained by combining the detection signals output from a pair of detection coils so as to obtain a difference, and a second combined signal, which is obtained by combining the detection signals output from a pair of detection coils so as to superimpose, over time; a monitoring spectrum generation step in which the state monitoring device performs 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 monitored object corresponding to the monitoring frequency band is normal or abnormal based on a comparison of the latest monitoring spectrum and the reference spectrum in the monitoring frequency band.

[0011] A frequency band setting method in one embodiment of the present invention is a frequency band setting method for a monitored target, which is performed by a state monitoring device that monitors the state of the monitored target of the pump, based on the detection signals of each of at least one detection coils that detect a change in magnetic flux corresponding to the displacement of the rotor position relative to the stator of the pump motor, wherein the detection coil is mounted on the stator so as to be able to detect the change in magnetic flux corresponding to the displacement of the rotor in the radial direction and outputs the detection signal indicating the change in magnetic flux, and the frequency band setting method comprises a parameter acquisition step in which the state monitoring device acquires parameters based on the specifications of the monitored target, The state monitoring device includes a theoretical monitoring frequency band calculation step of calculating a theoretical monitoring frequency band for each monitored object based on the parameters; a rotation component acquisition step of the state monitoring device acquiring 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 of the state monitoring device calculating 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 of the state monitoring device correcting the theoretical monitoring frequency band with the correction value to calculate the monitoring frequency band.

[0012] This invention allows monitoring of the state of the pump's target, which manifests as a periodic displacement of the rotor's position.

[0013] This is a cross-sectional view of the pump, showing an embodiment of the pump according to the present invention. This is a functional block diagram of a condition monitoring device, showing an embodiment of the condition monitoring device according to the present invention. This is a schematic perspective view of the stator core of the pump, showing the arrangement of the detection coil of the condition monitoring device. This is an enlarged perspective view of part A in Figure 3. This is a schematic diagram showing an example of the detection signal of the detection coil. (a) This is a frequency characteristic diagram showing an example of a monitoring spectrum generated by the condition monitoring device, and (b) This is a frequency characteristic diagram showing an example of a comparison spectrum. This is a schematic diagram showing an exceptional monitoring frequency band used in the condition monitoring device. This is a schematic diagram showing an example of information stored in the memory unit of the condition monitoring device. This is a schematic diagram showing an example of another piece of information stored in the memory unit. This is a flowchart showing an example of the operation of the condition monitoring device. This is a flowchart showing an example of an initial adjustment process included in the operation. This is a flowchart showing an example of a condition monitoring process included in the operation. (a) This is a frequency characteristic diagram showing an example of a monitoring spectrum generated by the condition monitoring device, and (b) This is a frequency characteristic diagram showing an example of a comparison spectrum.

[0014] Embodiments of the condition monitoring device (hereinafter referred to as "the device"), pump, condition monitoring program (hereinafter referred to as "the program"), condition monitoring method (hereinafter referred to as "the monitoring method"), and frequency band setting method (hereinafter referred to as "the setting method") according to the present invention are described below. In the following description, the drawings will be referenced as appropriate. In each drawing, the same reference numerals are used for the same members and elements, and redundant explanations are omitted. In addition, the dimensional ratios of each element may be exaggerated for the sake of explanation, and are not limited to the ratios shown in each drawing.

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

[0016] In the following explanation, "downward" refers to the direction of gravity, and "upward" refers to the opposite direction of downward.

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

[0018] Figure 1 is a cross-sectional view of 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). Some components are shown in non-cross-sectional view.

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

[0020] The housing 2 houses the motor unit 3, impellers 51 and 52, and diffusers 61 and 62. The shape of the housing 2 is substantially cylindrical along the vertical direction. The housing 2 is provided with an inlet 21 and an outlet (not shown; the same applies hereinafter). The lower end of the housing 2 is tapered in diameter, forming the inlet 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 comprises 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 rotational power to the impellers 51 and 52. The rotating shaft 30 has a cylindrical shape that is aligned vertically. The rotating shaft 30 is inserted through the rotor 33. The lower part 30a of the rotating shaft 30 extends downward from the rotor 33.

[0023] In the following explanation, "thrust direction" refers to the axial direction of the rotation axis 30, "radial direction" refers to the radial direction of the rotation axis 30, and "circumferential direction" refers to the circumferential direction of the rotation axis 30.

[0024] Bearing 31 is positioned above the rotor 33 and rotatably supports the rotating shaft 30. Bearing 32 is positioned below the rotor 33 and rotatably supports the rotating shaft 30. Bearing 31 is a known rolling bearing comprising, for example, an inner ring 31a, an outer ring 31b, a plurality of rolling elements 31c, and a cage (not shown; the same applies hereinafter). Bearing 32 is a known rolling bearing comprising, for example, 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 rotor 33 is cylindrical in shape. The rotor 33 is equipped with a plurality (28 in this embodiment) of rod-shaped rotor bars 33a embedded at equal intervals in the outer peripheral edge of the rotor 33 in the circumferential direction. When the bearings 31 and 32 are not worn, the rotor 33 is positioned in its initial position relative to the stator 34. In this embodiment, the "initial position" in the radial direction is the 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 that rotates the rotor 33. The stator 34 has a substantially cylindrical shape. The stator 34 comprises a stator core 34a and a plurality of motor windings 34b.

[0027] The stator core 34a holds the motor windings 34b. The stator core 34a has a cylindrical shape. The stator core 34a is provided with a plurality of teeth 34c (see Figure 4; the same applies hereafter).

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

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

[0030] The "monitoring target" is the object (component of the pump 1) whose state is monitored by this device 4. The monitoring target includes the rotating shaft 30 and members that are in contact with the rotating shaft 30 and whose position relative to the stator 34 is periodically displaced in accordance with the rotation of the rotating shaft 30 (hereinafter referred to as "displacement members"). Displacement members include, for example, the rotor 33, bearings 31, 32 and impellers 51, 52. More broadly, the monitoring target includes members whose state manifests as a periodic displacement of the rotor 33 in the radial direction. For example, when the monitoring target is vibrating, if an abnormality occurs in the monitoring target (e.g., wear, damage, foreign matter adhesion, increased mechanical load, etc.), the vibration changes (e.g., change in frequency, change in amplitude, etc.). When this vibration is transmitted to the rotor 33, its state manifests as a periodic displacement of the rotor 33 in the radial direction.

[0031] "State" includes both normal and abnormal.

[0032] The rotating shaft 30 rotates periodically at the same rotational speed as the rotor 33 when the rotor 33 rotates. The rotating shaft 30 is supported by bearings 31 and 32, which have a slight amount of play in the radial direction. The rotating shaft 30 is cylindrical, but not a perfect cylinder without any errors. Therefore, when the rotating shaft 30 rotates, the positions of the rotating shaft 30 and the rotor 33 are slightly and periodically displaced (vibrated) in the radial direction, even if they are functioning normally. The position of the displacement member is also periodically displaced in accordance with the rotation of the rotating shaft 30. This periodic displacement of position manifests as vibration of the rotating shaft 30, that is, as periodic displacement of the rotor 33 in the radial direction. Furthermore, vibrations of some of the components of the pump 1, in addition to the displacement member, are transmitted to the rotor 33 via the rotating shaft 30 and manifest as periodic displacement of the rotor 33 in the radial direction. Furthermore, cavitation and pressure fluctuations occurring in the fluid being handled, rather than in the components of the pump 1, are also transmitted to the rotor 33 via the impellers 51 and 52 and the rotating shaft 30, and appear as periodic displacements of the rotor 33 in the radial direction. This device 4 can detect these periodic displacements (vibrations) as periodic displacements of the rotor 33 in the radial direction using detection coils C1 to C4 (see Figure 2).

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

[0034] The diffusers 61 and 62 are attached to the housing 2. Diffuser 61 is positioned between the impeller 51 and the impeller 52, adjacent to them. Diffuser 62 is positioned above the impeller 52, adjacent to the impeller 52.

[0035] ●Status Monitoring Device● ●Configuration of the Status Monitoring Device Next, the configuration of this device 4 will be explained. In the following explanation, Figure 1 will be referred to as appropriate.

[0036] Figure 2 is a functional block diagram of the device 4, showing an embodiment of the device 4.

[0037] The device 4 comprises four detection coils C1, C2, C3, and C4, a connection unit 40, signal processing units 41a and 41b, a control unit 42, a storage unit 43, and a display unit 44. The connection unit 40, signal processing units 41a and 41b, and the control unit 42 are implemented, for example, by a microcomputer.

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

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

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

[0041] In the circumferential direction, detection coils C1 and C2 are mounted at equal angular intervals on the upper end of the tooth portion 34c (at the same position in the thrust direction). That is, the angular interval between detection coils C1 and C2 in the circumferential direction is 180°, and detection coil C1 is positioned to face detection coil C2. In the circumferential direction, detection coils C3 and C4 are mounted at equal angular intervals on the lower end of the tooth portion 34c. That is, the angular interval between detection coils C3 and C4 in the circumferential direction is 180°, and detection coil C3 is positioned to face detection coil C4. That is, in the radial direction, detection coils C1 and C3 are positioned to face their corresponding detection coils C2 and C4.

[0042] In the present invention, the detection coil C2 may be arranged at a position different from 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 have opposite phases and cancel each other out. This relationship is similarly applicable to the detection coils C3 and C4. Further, the detection coils C3 and C4 may be arranged at positions different from 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 waveforms corresponding to changes in the main magnetic flux of the motor unit 3 (hereinafter referred to as "fundamental wave components"), and waveforms corresponding to changes in the magnetic flux generated by the induced current flowing through the rotor bar 33a (hereinafter referred to as "harmonic components"). The fundamental wave component is generated by the drive voltage of the drive power supply 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 magnetic flux due to the rotor bar 33a 28 times while the rotor 33 makes one rotation. 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 rotational 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 rotational 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, Figures 1 to 3 will be primarily referenced. Detection coils C1 to C4 detect the displacement of the rotor 33 in the radial direction by detecting changes in magnetic flux corresponding to the displacement of the rotor 33 in the radial direction (including displacement of positional relationship and periodic displacement). Detection coil C1 is electrically connected to the common path Lc1 and detection coil C2. Detection coil C2 is electrically connected to the signal path L11 via the connection part 50. Detection coils C1 and C2 are connected in series so that the difference between their detection signals is obtained (so that the detection signals cancel each other out), and function as a pair of detection coils in the present invention. Detection coil C3 is electrically connected to the common path Lc2 and detection coil C4. Detection coil C4 is electrically connected to the signal path L12 via the connection part 50. 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. Detection coils C1 and C2 are examples of a pair of first detection coils in the present invention. Detection coils C3 and C4 are examples of a pair of second detection coils in the present invention.

[0046] The signal level of the harmonic component increases in the radial direction as the rotor 33 approaches the detection coils C1 to C4, and decreases as 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 from the detection coils C1 to C4 have the characteristic of changing according to the displacement of the rotor 33 in the radial direction. By using this characteristic of the detection signal, the present invention makes it possible to monitor the state of the object being monitored, which appears as a periodic displacement of the rotor 33 in the radial direction.

[0047] Here, for example, when the rotor 33 approaches the detection coil C1, the amount of increase in the signal level of the harmonic component of the detection coil C2 increases as the angular interval between the detection coils C1 and C2 in the circumferential direction becomes smaller than "90°", and approaches the amount of increase in the signal level of the harmonic component of the detection coil C1. On the other hand, the amount of decrease in the signal level of the harmonic component of the detection coil C2 increases as the angular interval between the detection coils C1 and C2 in the circumferential direction becomes larger than "90°", and approaches the amount of increase in the signal level of the harmonic component of the detection coil C1. This relationship is similarly applicable 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 an 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 of detecting the radial displacement amount is well-known. Therefore, a detailed description thereof will be 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 overlap (be added), in the combined signal (hereinafter referred to as "combined signal (S34)"), the fundamental wave components are added, 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 decreases 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 section 40 is the interface to which detection coils C2 and C4 are connected. Common paths Lc1 and Lc2, detection coils C2 and C4, and signal paths L11 and L12 are connected to the connection section 40. Common paths Lc1 and Lc2 are connected to ground via the connection section 40.

[0051] The signal processing units 41a and 41b perform predetermined signal processing (for example, first filtering, absolute value conversion, second filtering, envelope processing, differentiation, and A / D conversion) on each combined signal (S12, S34). The signal processing units 41a and 41b include, for example, a first filter circuit (for example, a bandpass filter or a lowpass filter), an absolute value conversion circuit, a second filter circuit (for example, a lowpass filter), an envelope detection circuit, differentiation processing, and an A / D conversion circuit. The signal processing unit 41a is connected to the signal path L11 and performs predetermined signal processing on the combined signal (S12). The signal processing unit 41b is connected to the signal path L12 and performs predetermined signal processing on the combined signal (S34).

[0052] Here, each composite signal (S12, S34) is a signal indicating periodic displacement of position. By performing differential processing on these signals, the resulting signal becomes a signal indicating velocity. Furthermore, by performing differential processing on the velocity signal, the resulting signal becomes a signal indicating acceleration. Each signal has its own strengths in handling vibration phenomena and frequency bands. Therefore, by performing these processes according to the phenomenon being monitored, the state of the monitored object can be monitored with higher precision.

[0053] The control unit 42 controls the operation of the entire device 4. The control unit 42 includes, for example, a processor such as a CPU (Central Processing Unit) 42a, volatile memory such as a RAM (Random Access Memory) 42b that functions as a work area for the CPU 42a, and non-volatile memory such as a ROM (Read Only Memory) 42c that stores various information such as the 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 runs and works in cooperation with the hardware resources of the device 4 to realize the monitoring method described later. Furthermore, by causing the processor (CPU 42a) constituting the control unit 42 to execute this program, the program causes the processor to function as an acquisition unit 420, a spectrum generation unit 421, a first calculation unit 422, a second calculation unit 423, a correction unit 424, and a determination unit 425, thereby causing the processor to execute the monitoring method. Moreover, by causing a computer to execute this program, the program can cause the computer to function as the device 4.

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

[0056] The acquisition unit 420 acquires each combined 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 performs FFT processing on the signal (composite 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 contained in each composite signal (S12, S34). The monitoring spectrum includes the fundamental wave component, high-frequency components, and vibration components corresponding to the monitored object (e.g., rotation frequency). The frequency resolution of the monitoring spectrum is appropriately changed by the spectrum generation unit 421 according to the monitored object. That is, the resolution is set appropriately according to the monitored object. By making the resolution of the monitoring spectrum variable in this way, it becomes possible to use different resolutions, for example, by setting a high resolution for monitored objects where it is necessary to determine the positional shift (frequency) of the monitoring peak (described later), and a low resolution for monitored objects where such determination is not necessary. As a result, the computational load is minimized, and memory usage can be reduced. In this embodiment, the monitoring spectrum includes a first monitoring spectrum generated based on the composite signal (S12) and a second monitoring spectrum generated based on the composite signal (S34).

[0059] Figure 6(a) is a frequency response diagram showing an example of a monitoring spectrum generated by the device 4, and (b) is a frequency response diagram showing an example of a comparative spectrum (hereinafter referred to as the "comparative spectrum"). Figure 6(a) shows the first monitoring spectrum. Figure 6(b) shows the comparative spectrum obtained by performing FFT processing on the signal from the acceleration sensor attached to the pump 1.

[0060] As shown in Figure 6(a), the monitoring spectrum shows a strong peak at the drive frequency (hereinafter referred to as the "power peak"). In particular, the power peaks of odd harmonics are strongly present, while the intensity of the power peaks of even harmonics is less than half that of the power peaks of odd harmonics. Also, as shown in Figures 6(a) and 6(b), the monitoring spectrum also shows sufficient intensity for the power peaks of odd harmonics of the 11th order and above. On the other hand, in the comparison spectrum, harmonics of the 11th order and above are attenuated and do not have sufficient intensity to be extracted. Furthermore, no trend is observed 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 a composite signal from two detection coils C1 and C2. In Figure 6(a), "fb1" shows the monitoring peak of the 7th harmonic of the rotation frequency of the rolling element 31c, and "fb2" shows the monitoring peak of the 7th harmonic of the rotation frequency of the rolling element 32c. On the other hand, no monitoring peaks corresponding to "fb1" and "fb2" appear in Figure 6(b). Thus, while higher-order monitoring peaks with extractable intensity appear in the monitoring spectrum, similar monitoring peaks do not appear in the comparison spectrum. In this device 4, by using the monitoring spectrum, it becomes possible to monitor the state of the target object using higher-order harmonic monitoring peaks that cannot be achieved with an acceleration sensor.

[0061] Here, the positions of most of the monitoring peaks appearing in the first monitoring spectrum are the same as the positions of the monitoring peaks appearing in the second monitoring spectrum. However, the inventors of the present invention have discovered that some monitoring peaks appear in only one of the first or second monitoring spectra. Furthermore, the inventors of the present invention have discovered that the intensities of monitoring peaks common to the first and second monitoring spectra are different. This is presumed to be due to the different methods of combining the combined signal (S12) and the combined signal (S34). By using two types of combined signals (S12, S34), the device 4 can monitor the state of a wider variety of monitoring targets.

[0062] In the following description, Figures 1 and 2 will be the primary references. The first calculation unit 422 calculates the theoretical monitoring frequency band for each monitored object based on parameters set according to the specifications of the monitored object. The 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] "Parameters" are numerical values ​​included in the specifications of the monitored object and are necessary for calculating the theoretical monitoring frequency. For example, if the monitored object is a bearing 31 or 32, the parameters may include the outer diameter of the inner rings 31a and 32a, the inner diameter of the outer rings 31b and 32b, and the diameter, number, contact angle, and rotational frequency of the rolling elements 31c and 32c (or the rotational frequency of the rotating shaft 30). Also, if the monitored object is an impeller 51 or 52, the parameters may include the number of blades and the rotational frequency. For example, the parameters are set (input) into this device 4 in advance before the pump 1 is shipped and stored in the memory unit 43.

[0064] The "theoretical monitoring frequency" is a theoretical frequency that indicates the periodic displacement of the position of the monitored object. The theoretical monitoring frequency is, for example, the vibration frequency of the monitored object when the rotor 33 is rotating at a set rotational 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 monitored object is a bearing 31, the theoretical monitoring frequency is the inner ring rolling element passing frequency (inner ring pulse generation frequency), the outer ring rolling element passing frequency (outer ring pulse generation frequency), the rolling element rotation frequency, or the rolling element revolution frequency. When the monitored 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 the frequency corresponding to that part (for example, the inner ring rolling element passing frequency). Also, for example, when the monitored objects are impellers 51 and 52, the theoretical monitoring frequency is the rotational frequency of the impellers 51 and 52.

[0065] The "theoretical monitoring frequency band" is a predetermined frequency band that includes the theoretical monitoring frequency. The theoretical monitoring frequency band is set, for example, within a range of ± several Hz (for example, ± 5 Hz) centered on the theoretical monitoring frequency. Each theoretical monitoring frequency band corresponds to a monitored object, and the number of such bands is, for example, greater than or equal to the number of monitored objects.

[0066] The second calculation unit 423 calculates a correction value based on the set rotational speed and measured rotational 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 a correction value calculation unit in the present invention.

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

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

[0069] The "correction value" is a coefficient used to correct the theoretical monitoring frequency band to the actual monitoring frequency band in pump 1 where "slip" is occurring. The theoretical monitoring frequency is calculated assuming that the rotor 33 is rotating at a set rotational speed. Therefore, the actual monitoring frequency when the rotor 33 is rotating at a measured rotational speed is slightly smaller than the theoretical monitoring frequency due to the effect of "slip". For this reason, in order to accurately monitor the state of the monitored object when pump 1 is operating (when "slip" is occurring), it is necessary to correct the theoretical monitoring frequency to match the actual monitoring frequency. The correction value is, for example, the ratio of the set rotational speed to the measured rotational speed. In this embodiment, the correction value is the ratio of the rotor rotation component frequency determined by the set rotational speed (calculated harmonic component: hereinafter referred to as "theoretical rotation component") to the rotor rotation component frequency determined by the measured rotational speed (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" is occurring. The monitoring spectrum includes harmonic components (rotor rotation components). Therefore, the device 4 can calculate a 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 a 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 predetermined frequency range that includes the actual monitoring frequency, taking "slip" into account. For example, the monitoring frequency band is set within a range of ± a few 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 mentioned above, the detection signals from detection coils C1 to C4 include a fundamental wave component. In addition, in pump 1, one rotating shaft 30 serves as both the motor shaft and the pump shaft. That is, in pump 1, the pump configuration and the motor configuration are integrated. Therefore, the drive frequency of the drive power supply strongly appears 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 supply 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 supply peak, the monitoring peak will be included in the power supply peak. In this case, if the frequency resolution is set very high, the monitoring peak can be distinguished (extracted) from the power supply peak. However, as the frequency resolution is set higher, the processing time and load for FFT analysis and other processes may increase. On the other hand, if the frequency resolution is set low, the monitoring peak cannot be distinguished (extracted) from the power supply peak. Here, the interval (frequency) between the monitoring peak and the power supply peak at the fundamental frequency increases proportionally to the order of the harmonic. Therefore, when the frequency resolution is set low, the monitoring frequency band for such a monitored object should be set to a frequency band centered on (containing) high-order harmonics such that the interval increases until the monitoring peak becomes distinguishable. In other words, the monitoring frequency band is set based on the peak of the nth harmonic spectrum where the nth harmonic frequency (n is an integer of 3 or more) of the monitoring peak is located outside a predetermined frequency range centered on the nth harmonic frequency of the power supply peak. For example, when the predetermined frequency range is "±b" Hz and the interval between the power supply peak and the monitoring peak at the fundamental frequency is "a" Hz (a < b), the monitoring frequency band is exceptionally set to include the nth harmonic frequency that satisfies the relationship "n × a > b".

[0073] Figure 7 is a schematic diagram showing the exceptional monitoring frequency band used in this device 4. The figure shows that, by satisfying the relationship "n × a > b", the monitoring peak can be easily separated from the power peak at the nth harmonic frequency.

[0074] In the following explanation, Figure 2 will be the primary reference. The determination unit 425 determines whether the state of the monitored object corresponding to the monitored frequency band is normal or abnormal based on a comparison of the monitored spectrum and the reference spectrum in the monitored frequency band. The specific operation of the determination unit 425 will be described later.

[0075] The "reference spectrum" is a spectrum used for comparison with the monitoring spectrum. The reference spectrum is, for example, one of the monitoring spectra generated over time by the device 4 (spectrum generation unit 421). In this embodiment, the reference spectrum is a monitoring spectrum generated when the state of the monitored object is normal. The reference spectrum includes a first reference spectrum used for comparison with the first monitoring spectrum and a second reference spectrum used for comparison with the second monitoring spectrum.

[0076] "Comparison-based judgment" is performed on at least one of the following: location, intensity, or shape of the monitored 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 memory unit 43 stores information necessary for the operation of the device 4 (for example, theoretical monitoring frequency band, monitoring frequency band, correction value, reference spectrum, etc.). The memory unit 43 is a non-volatile memory such as EEPROM (Electrically Erasable Programmable Read-Only Memory) or flash memory.

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

[0080] Figure 9 is a schematic diagram showing an example of other information (correction value) stored in the memory 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 explanation, Figure 2 will be the primary reference. The display unit 44 displays the status of the monitored object. For example, the display unit 44 displays the status of each monitored object using "green (normal)" and "red (abnormal)".

[0082] ●Pump Operation Next, the operation of pump 1 will be explained below, focusing on the operation of this device 4. Figures 1 and 2 will be referred to as appropriate in the following explanation.

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

[0084] The device 4 performs an initial adjustment process (ST1), and then performs a status 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 performed to calculate the monitoring frequency band before the execution of the status monitoring process (ST2). The initial adjustment process (ST1) is performed, for example, before the pump 1 is shipped or after maintenance of the pump 1. In other words, the initial adjustment process (ST1) is performed when the monitored object is in a normal state. By performing the initial adjustment process (ST1), the device 4 can monitor the state of the monitored object based on the monitoring frequency band corresponding to "slip". The initial adjustment process (ST1) is an example of this setting method.

[0087] First, the acquisition unit 420 acquires each parameter of the monitored device (ST11: parameter acquisition step). As mentioned above, the parameters are pre-set in the device 4 and stored in the storage unit 43.

[0088] Next, the first calculation unit 422 calculates a theoretical monitoring frequency band for each monitored object (ST12: first calculation step). As described above, the theoretical monitoring frequency is calculated based on 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, associated with the monitored object. At this time, the first calculation unit 422 also calculates a theoretical monitoring frequency band that includes 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, the pump 1 starts operating, and the acquisition unit 420 acquires a composite signal (S12, S34) when the pump 1 is operating (i.e., when "slip" is occurring) (ST13: signal acquisition step). This acquisition is performed at a predetermined sampling frequency. The sampling frequency is set to more than twice the rotor rotation component frequency (for example, 5 kHz). While the pump 1 is operating, the motor unit 3 is supplied with power, and the rotor 33, rotating shaft 30, and impellers 51, 52 rotate at a predetermined rotational speed (measured rotational speed).

[0090] Next, the spectrum generation unit 421 performs FFT processing on the composite signal (S12) acquired by the acquisition unit 420 to generate a first monitoring spectrum, and then performs 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 the first reference spectrum, and the second monitoring spectrum is stored in the storage unit 43 as the second reference spectrum. In other words, the first reference spectrum and the second reference spectrum are the monitoring spectra acquired over time that were acquired (first) when the state of the monitored object was normal.

[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 in the theoretical monitoring frequency band centered on the calculated set rotation component as the measured 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, for example, in association with the set rotation component and the measured rotation component. 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 a 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 by multiplying the theoretical monitoring frequency band by a correction value, for example. The monitoring frequency band is associated with the monitoring target and stored in the storage unit 43.

[0094] ●Status monitoring process Figure 12 is a flowchart showing an example of the status monitoring process (ST2).

[0095] "Status monitoring process (ST2)" is a process that monitors the status of the monitored object while pump 1 is operating. Status monitoring process (ST2) is an example of this monitoring method.

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

[0097] Next, the spectrum generation unit 421 performs FFT processing on the composite signal (S12) acquired by the acquisition unit 420 to generate a first monitoring spectrum, and then performs FFT processing on the composite 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] Figure 13(a) is a frequency response diagram showing an example of a monitoring spectrum (second monitoring spectrum) generated by the device 4, and (b) is a frequency response diagram showing an example of a comparison spectrum.

[0099] The figure shows that at the monitoring frequency (outer wheel rolling element passing frequency: approximately 128 Hz), the intensity of the peak in the second monitoring spectrum during abnormal conditions is higher than the intensity during normal conditions. Furthermore, the figure shows that the peak intensity of the second monitoring spectrum at the monitoring frequency fluctuates similarly to the peak intensity of the comparison spectrum.

[0100] Next, the determination unit 425 acquires the spectrum of the monitoring frequency band (hereinafter referred to as "individual monitoring spectrum") from the latest first monitoring spectrum and acquires the individual monitoring spectrum from the latest second monitoring spectrum (ST23). An 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 (hereinafter referred to as the "individual reference monitoring spectrum") and acquires the individual reference monitoring spectrum from the second reference spectrum (ST24). An individual reference spectrum is acquired for each monitoring target (reference monitoring frequency band).

[0102] In this invention, individual reference spectra 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 individual monitoring spectrum for each monitored target (monitoring frequency band) (ST25: comparison step). As described above, the comparison is performed on at least one of the following: intensity, position, or shape of the monitoring peak.

[0104] Next, the determination unit 425 compares the comparison result with a predetermined threshold and determines, for example, whether the comparison result is within the predetermined threshold (ST26: determination process). When the state of the monitored object is abnormal, the intensity of the monitoring peak corresponding to that monitored object fluctuates significantly. Therefore, the determination unit 425 can determine that "the state of the monitored object is abnormal" when the amount of fluctuation in intensity is greater than the predetermined threshold. Similarly, when the state of the monitored object is abnormal, the position (frequency) of the monitoring peak corresponding to that monitored object may fluctuate. For example, when the monitored objects are rolling elements 31c and 32c, if 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, the determination unit 425 can determine that "the state of the monitored object is abnormal" when the amount of fluctuation in position is greater than the predetermined threshold. Furthermore, the FFT processing is calculated using the average value over a specific period. Therefore, when the "slip" changes continuously in response to the load, the shape of the monitoring peak (the shape of the spectrum) fluctuates (becomes blunted). Here, the monitoring spectrum is a set of discrete values ​​in units of resolution (e.g., 1 Hz). Therefore, the shape of the monitoring peak can be recognized based on the relative magnitudes of the intensities before and after the monitoring peak. The determination unit 425 can recognize each shape as an area by calculating the integral value of the individual monitoring spectrum and the individual reference monitoring spectrum, and compare them. A predetermined threshold value is determined in advance and stored in the storage unit 43.

[0105] When the comparison result is within a predetermined threshold ("Y" in ST26), the determination unit 425 determines that "the state of the monitored object is normal," and the display control unit 426 displays "Normal" on the display unit 44 (ST27).

[0106] On the other hand, when the comparison result is greater than a predetermined threshold ("N" in ST26), the determination unit 425 determines that "the state of the monitored object is abnormal," and the display control unit 426 displays "abnormal" on the display unit 44 (ST28).

[0107] ●Summary According to the embodiment described above, the device 4 comprises 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 and C2, and a pair of detection coils C3 and 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 different positions from the detection coils C3 and C4. The acquisition unit 420 acquires each combined signal (S12, S34) over time. The spectrum generation unit 421 performs FFT processing on the signals acquired by the acquisition unit 420 (each combined signal (S12, S34)) to generate a monitoring spectrum. The determination unit 425 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. The storage unit 43 stores the monitoring frequency band and the reference spectrum that are pre-set for the monitored object. 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. With this configuration, the device 4 can monitor the state of the monitored object, which appears as a periodic displacement of the rotor 33 in the radial direction. The monitoring spectrum is generated based on each composite signal (S12, S34). Therefore, the monitoring spectrum also contains higher-order harmonics that do not appear in the comparison spectrum. Thus, by using the monitoring spectrum, the device 4 can achieve state monitoring based on monitoring peaks of higher-order harmonics, which cannot be achieved with an acceleration sensor.

[0108] Furthermore, according to the embodiment described above, the device 4 comprises a first calculation unit 422, a second calculation unit 423, and a correction unit 424. With this configuration, even if the theoretical monitoring frequency band is out of sync with the actual monitoring frequency band due to "slip," the device 4 can monitor the state of the monitored object in the same monitoring frequency band by correcting it with a correction value. In other words, the device 4 realizes state monitoring of the monitored object that is compatible with "slip."

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

[0110] Furthermore, according to the embodiments described above, the reference spectrum is the monitoring spectrum acquired (first) when the state of the monitored object is normal, from 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 mentioned above, the monitored object is a component whose state appears as a periodic displacement of the position of the rotor 33 in the radial direction. Therefore, the state of the monitored object can be determined by the fluctuation of the position, intensity, or shape of the monitoring peak. Accordingly, the device 4 can easily monitor the state of the monitored object by comparing the monitoring peaks.

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

[0112] Furthermore, according to the embodiments described above, the device 4 includes signal processing units 41a and 41b. The signal processing includes filtering, absolute value conversion, envelope conversion, and differentiation. With this configuration, the monitored peaks are enhanced in the monitored spectrum. Therefore, the accuracy of state monitoring by the device 4 is improved. In addition, by performing differentiation processing according to the phenomenon to be monitored, the state of the monitored object can be monitored with higher accuracy.

[0113] Furthermore, according to the embodiment described above, the pump 1 comprises a rotating shaft 30, bearings 31 and 32, a rotor 33, a stator 34, detection coils C1 to C4, and the device 4. With this configuration, the pump 1 can monitor the state of the object being monitored by the device 4.

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

[0115] Furthermore, in the present invention, the device 4 may be equipped with only one of the detection coils C1 to C4 (for example, detection coil C1). In this case, in the initial adjustment process (ST1) and the state monitoring process (ST2), the detection signal is used instead of the combined signals (S12, S34). That is, the monitoring frequency band (theoretical monitoring frequency band, correction value) and the reference spectrum are set in accordance with 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 generates a monitoring spectrum by performing FFT processing on the detection signal acquired by the acquisition unit 420. The determination unit 425 determines whether the state of the monitored target corresponding to the monitoring frequency band is normal or abnormal based on a comparison of 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 monitored targets using the monitoring peaks of higher harmonics. However, the device 4 can monitor the state of other monitored targets excluding the monitored target.

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

[0117] Furthermore, in the present invention, the detection coils C1, C2 and C3, C4 do not have to be connected in series. In this case, the device 4 includes a combining circuit (for example, a subtraction circuit) that combines the detection signals of the detection coils C1 and C2 so as to obtain their difference, and a combining circuit (for example, an addition circuit) that combines the detection signals of the detection coils C3 and C4 so as to superimpose them.

[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 and C2 may be different from the number of turns of the detection coils C3 and 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 so as to obtain the difference between their detection signals.

[0121] ●Signal Processing Unit Furthermore, in the present invention, the device 4 does not necessarily have to include signal processing units 41a and 41b. In this case, the device 4 includes an A / D conversion unit that converts each combined signal (S12, S34) into a digital signal. The acquisition unit 420 acquires each combined signal (S12, S34) that has been converted into a digital signal.

[0122] Furthermore, in the present invention, the signal processing performed by the signal processing units 41a and 41b is not limited to first filtering, absolute value conversion, second filtering, envelope processing, differentiation, and A / D conversion processing, as long as it is a process that can extract the monitored peak.

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

[0124] Furthermore, in the present invention, the device 4 may be comprised of either the signal processing unit 41a or the signal processing unit 41b, or both.

[0125] ●Control Unit Furthermore, in the present invention, the sampling frequency at which the acquisition unit 420 acquires the signal is a 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 does not necessarily have to include the first calculation unit 422. In this configuration, the theoretical monitoring frequency is calculated in advance before the pump 1 is shipped, for example, by an external device (for example, a computer), and stored in the storage unit 43.

[0127] Furthermore, in the present invention, the control unit 42 does not necessarily have to 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 to correspond to the "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 within a range of ± a few percent centered on the theoretical monitoring frequency (monitoring frequency).

[0129] Furthermore, in the present invention, one monitoring frequency band may be set for one monitored object, or multiple monitoring frequency bands may be set.

[0130] Furthermore, in the present invention, the correction value may be the ratio of the set rotational speed to the measured rotational 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 a 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 at a time when the object being monitored by pump 1 is reliably functioning normally (for example, after the initial operation of pump 1, or after maintenance of pump 1).

[0135] Furthermore, in the present invention, the determination unit 425 may also determine whether a state other than normal or abnormal for the monitored object is present or absent if it appears as a monitoring peak.

[0136] ●Pump Furthermore, in the present invention, the pump 1 may be any pump to which 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 impellers 51 and 52 provided in the pump 1 is not limited to "2".

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

[0139] ●Furthermore, in the present invention, the object to be monitored (the nature of the abnormality) may also be the rotor bar 33a (rotor bar 33a breakage), the rotating shaft 30 (misalignment of the rotating shaft 30), or the motor unit 3 (insulation failure). Also, when the object to be monitored is the impeller 51, 52, the device 4 may monitor the presence or absence of cavitation transmitted to the rotor 33 as vibration of the impeller 51, 52 as the state of the impeller 51, 52.

[0140] Furthermore, in the present invention, the object to be monitored can be arbitrarily set according to the installation environment of the pump 1, and is not limited to this 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 Invention● Next, embodiments of the invention as understood from the embodiments described above will be described below, with reference to the terms and reference numerals described in each embodiment.

[0142] A first embodiment of the present invention is a condition monitoring device (e.g., condition monitoring device 4) that monitors the state of a monitored object of a pump (e.g., a rotating shaft 30, bearings 31, 32, rotor 33, impellers 51, 52) 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 the displacement of the rotor (e.g., rotor 33) relative to the stator (e.g., stator 34) of the motor (e.g., motor unit 3) of a pump (e.g., pump 1), wherein the plurality of detection coils include a pair of detection coils (e.g., detection coils C1, C2, detection coils C3, C4) that are mounted on the stator so as to be able to detect the change in magnetic flux corresponding to the displacement of the rotor in the radial direction, and that output the detection signals indicating the change in magnetic flux, and the detection signals are synthesized, and each 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. The state monitoring device comprises: an acquisition unit (e.g., acquisition unit 420) that 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 detection coils 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 detection coils to superimpose, over time; a spectrum generation unit (e.g., spectrum generation unit 421) that performs 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 pre-set for the monitoring target and a reference spectrum to be compared with 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 of the latest monitoring spectrum and the reference spectrum in the monitoring frequency band. With this configuration, the device can monitor the state of the monitoring target, which appears as a periodic displacement of the rotor position in the radial direction.

[0143] A second embodiment of the present invention is a state monitoring device in which, in the first embodiment, the plurality of detection coils include a pair of first detection coils (e.g., detection coils C1, C2) that function as a pair of detection coils and output the detection signal that forms the basis of the first composite signal, and a pair of second detection coils (e.g., detection coils C3, C4) that function as a pair of detection coils and output the detection signal that forms the basis of the second composite signal, wherein the first detection coils are arranged at positions different from 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 processing on the first composite signal and a second monitoring spectrum generated by performing the FFT processing on the second composite signal, and the reference spectrum includes a first reference spectrum that is the basis of the first monitoring spectrum and a second reference spectrum that is the basis of the second monitoring spectrum. With this configuration, the device can monitor the state of a wider variety of monitoring targets by using two types of composite signals.

[0144] A third embodiment of the present invention is a condition monitoring device comprising: a theoretical monitoring frequency band calculation unit (e.g., a first calculation unit 422) that calculates a theoretical monitoring frequency band for each monitored object based on parameters set according to the specifications of the monitored object in the first or second embodiment; a correction value calculation unit (e.g., a second calculation unit 423) that calculates a correction value based on the set rotational speed of the rotor set for the pump and the measured rotational speed of the rotor measured when the pump is operating; and a correction unit (e.g., a correction unit 424) that corrects the theoretical monitoring frequency band with the correction value to calculate the monitoring frequency band. With this configuration, the device realizes condition monitoring of the monitored object corresponding to "slip".

[0145] A fourth embodiment of the present invention is a state monitoring device in which, in the third embodiment, the acquisition unit acquires the signal at a predetermined sampling frequency, the sampling frequency being set to at least twice the rotor rotation component frequency corresponding to the change in magnetic flux generated by the induced current flowing through the rotor bar (e.g., rotor bar 33a) of the rotor, and 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 theoretical rotor rotation component frequency determined by the set rotation speed and the rotor rotation component frequency determined by the measured rotation speed. With this configuration, the device can easily and accurately calculate the correction value.

[0146] A fifth embodiment of the present invention is a state monitoring device in which, in the first embodiment, the reference spectrum is 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. With this configuration, the device can easily monitor the state of the object being monitored by comparing the monitoring peaks.

[0147] A sixth embodiment of the present invention is a state monitoring device in which, in the first embodiment, the monitoring spectrum includes a power peak indicating the drive frequency of the pump's power supply and a monitoring peak indicating a monitoring frequency determined for each monitored object, and when the fundamental frequency of the monitoring peak is located within a predetermined frequency range centered on the fundamental frequency of the power peak, the monitoring frequency band of the monitored object is set based on the peak of the spectrum of the nth harmonic (where n is an integer of 3 or more) whose nth harmonic frequency of the monitoring peak is located outside the predetermined frequency range centered on the nth harmonic frequency of the power peak. With this configuration, the device can monitor the state of a monitored object even if its monitoring peak is included within the power peak at its fundamental frequency.

[0148] A seventh embodiment of the present invention is a condition monitoring device in which, in the first embodiment, the monitored object includes the rotating shaft of the motor (e.g., rotating shaft 30), and / or a displacement member (e.g., rotor 33, bearings 31, 32, impellers 51, 52) that abuts against the rotating shaft and whose position is periodically displaced in accordance with the rotation of the rotating shaft. With this configuration, the device can monitor the condition of the rotating shaft, rotor, bearings, and impeller.

[0149] An eighth embodiment of the present invention is a state monitoring device in which, in the first embodiment, a signal processing unit (for example, signal processing units 41a, 41b) performs predetermined signal processing on at least one of the first combined signal and the second combined signal, and the acquisition unit acquires at least one of the first combined signal after signal processing and the second combined signal after signal processing over time. With this configuration, the accuracy of state monitoring by the device is improved.

[0150] A ninth embodiment of the present invention is a state monitoring device in which, according to the eighth embodiment, the signal processing includes filtering, absolute value conversion, envelope conversion, and differentiation. With this configuration, the accuracy of state monitoring by the device is improved.

[0151] A tenth embodiment of the present invention is a condition monitoring device (e.g., condition monitoring device 4) that monitors the state of a monitored object of the pump (e.g., a rotating shaft 30, bearings 31, 32, rotor 33, impellers 51, 52) based on a detection signal output from at least one detection coil (e.g., detection coil C1) that detects a change in magnetic flux corresponding to the displacement of the rotor (e.g., rotor 33) relative to the stator (e.g., stator 34) of the motor (e.g., motor unit 3) of the pump (e.g., pump 1), wherein the detection coil is mounted on the stator so as to be able to detect the change in magnetic flux corresponding to the displacement of the rotor in the radial direction and outputs the detection signal indicating the change in magnetic flux. The state monitoring device comprises: 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 performs 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 pre-set for the monitoring target and a reference spectrum to be compared with 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 of the latest monitoring spectrum and the reference spectrum in the monitoring frequency band. With this configuration, the device can monitor the state of the monitoring target, which appears as a periodic displacement of the rotor position in the radial direction.

[0152] An eleventh embodiment of the present invention is a pump (e.g., pump 1) comprising: a motor having 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 change in magnetic flux corresponding to the displacement of the rotor's position relative to the stator; and a state monitoring device (e.g., state monitoring device 4) according to the first or tenth embodiment that monitors the state of the object being monitored in the pump based on the detection signals from the detection coils. With this configuration, the state of the object being monitored in the pump can 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 a state monitoring device according to the first or tenth embodiment. With this configuration, the computer functions as a state monitoring device according to the present invention.

[0154] A thirteenth embodiment of the present invention is a state monitoring method (e.g., state monitoring process (ST2)) performed by a state monitoring device (e.g., state monitoring device 4) that monitors the state of a monitored object (e.g., a 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 the displacement of the rotor in the radial direction of the rotor, and outputting the detection signals indicating the change in magnetic flux, with the detection signals being synthesized, and the state monitoring device includes at least one monitoring frequency band preset for the monitored object, a reference spectrum, and The state monitoring method includes a storage unit (for example, storage unit 43) for storing information, and comprises: a signal acquisition step (for example, signal acquisition step (ST21)) in which the state monitoring device acquires at least one of a first combined signal (for example, combined signal (S12)) obtained by combining the detection signals output from a pair of detection coils so as to obtain a difference, and a second combined signal (for example, combined signal (S34)) obtained by combining the detection signals output from a pair of detection coils so as to superimpose, over time; a monitoring spectrum generation step (for example, monitoring spectrum generation step (ST22)) in which the state monitoring device performs FFT processing on the signal acquired in the signal acquisition step to generate a monitoring spectrum; and a determination step (for example, determination step (ST26)) 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 of the latest monitoring spectrum and the reference spectrum in the monitoring frequency band. With this configuration, the device can monitor the state of the object being monitored, which manifests as a periodic displacement of the rotor's position in the radial direction.

[0155] A fourteenth embodiment of the present invention is a frequency band setting method (e.g., initial adjustment process (ST1)) for setting a monitoring frequency band for a monitored object (e.g., rotating shaft 30, bearings 31, 32, rotor 33, impeller 51, 52) of a pump (e.g., pump 1), which is performed by a condition monitoring device (e.g., condition monitoring device 4) that monitors the state of the monitored object (e.g., rotating shaft 30, bearings 31, 32, rotor 33, impeller 51, 52) of the pump, 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 the displacement of the rotor in the radial direction, and output the detection signal indicating the change in magnetic flux, and the frequency band setting method is performed by the condition monitoring device which obtains parameters based on the specifications of the monitored object (e.g., The frequency band setting method includes: a parameter acquisition step (ST11); a theoretical monitoring frequency band calculation step (for example, a first calculation step (ST12)) in which the state monitoring device calculates a theoretical monitoring frequency band for each monitored object based on the parameters; a rotation component acquisition step (for example, a 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, a 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 for the pump and the rotor rotation component frequency determined by the measured rotation speed; and a correction step (for example, a 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. With this configuration, the device realizes state monitoring of a monitored object corresponding to "slip".

[0156] 1 Pump 3 Motor section (motor) 30 Rotating shaft (monitoring target) 31 Bearing (monitoring target, displacement member) 32 Bearing (monitoring target, displacement member) 33 Rotor (monitoring target, displacement member) 34 Stator 4 State 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 Storage unit 51 Impeller (monitoring target, displacement member) 52 Impeller (monitoring target, 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

A condition monitoring device that monitors the state of a pump based on detection signals output from a plurality of detection coils that detect changes in magnetic flux corresponding to the displacement of the rotor position relative to the stator of the pump motor, Multiple detection coils, Attached to the stator so as to be able to detect the magnetic flux change corresponding to the displacement of the rotor in the radial direction, The detection signal indicating the magnetic flux change is output, A pair of detection coils on which the detection signals are synthesized, Includes, Each of the pair of detection coils is positioned at the same location in the thrust direction of the rotor and at different locations in the circumferential direction of the rotor. An acquisition unit acquires at least one of the following over time: a first combined signal obtained by combining the detection signals output from a pair of detection coils so as to obtain a difference, and a second combined signal obtained by combining the detection signals output from a pair of detection coils so as to superimpose them. A spectrum generation unit performs 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 pre-set for the monitored object and a reference spectrum to be compared with the monitored spectrum, A determination unit that determines whether the state of the monitored target corresponding to the monitoring frequency band is normal or abnormal based on a comparison of the latest monitoring spectrum and the reference spectrum in the monitoring frequency band, Having, Condition monitoring device. 　 Multiple detection coils, A pair of first detection coils that function as a pair of detection coils and output the detection signal which forms the basis of the first composite signal, A pair of second detection coils that function as a pair of detection coils and output the detection signal which forms the basis of the second composite signal, Includes, The first detection coil is positioned differently from the second detection coil. The acquisition unit acquires the first combined signal and the second combined signal over time, The aforementioned monitoring spectrum is The first monitoring spectrum generated by performing the FFT processing on the first composite signal, The second monitoring spectrum is generated by performing the FFT processing on the second composite signal, Includes, The aforementioned reference spectrum is The first reference spectrum to be compared with the first monitoring spectrum, The second reference spectrum to be compared with the second monitoring spectrum, including, The status monitoring device according to claim 1. 　 A theoretical monitoring frequency band calculation unit calculates a theoretical monitoring frequency band for each monitored target based on parameters set according to the specifications of the monitored target, A correction value calculation unit calculates a correction value based on the set rotational speed of the rotor set for the pump and the measured rotational speed of the rotor 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, Having, A condition monitoring device according to claim 1 or 2. 　 The acquisition unit acquires the signal at a predetermined sampling frequency, The sampling frequency is set to be at least twice the rotor rotation component frequency corresponding to the change in magnetic flux generated by the induced current flowing through the rotor bar of the rotor. The correction value calculation unit, Based on the monitoring spectrum, the rotor rotation component frequency determined by the measured rotation speed is obtained, The correction value is calculated 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 status monitoring device according to claim 3. 　 The reference spectrum is one of the monitoring spectra generated over time. 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. The status monitoring device according to claim 1. 　 The aforementioned monitoring spectrum is The power supply peak indicating the drive frequency of the power supply for the pump, A monitoring peak indicating a monitoring frequency determined for each of the aforementioned monitored targets, Includes, 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 monitored target is set based on the peak of the spectrum of the nth harmonic (where n is an integer of 3 or more) whose nth harmonic frequency of the monitoring peak is located outside the predetermined frequency range centered on the nth harmonic frequency of the power supply peak. The status monitoring device according to claim 1. 　 The aforementioned monitored targets are: The rotating shaft of the aforementioned motor, and / or, A displacement member that contacts the rotating shaft and whose position is periodically displaced in accordance with the rotation of the rotating shaft, including, The status monitoring device according to claim 1. 　 A signal processing unit that performs predetermined signal processing on at least one of the first combined signal and the second combined signal, It has, The acquisition unit acquires at least one of the first combined signal after signal processing and the second combined signal after signal processing over time. The status monitoring device according to claim 1. 　 The aforementioned signal processing includes filtering, absolute value conversion, envelope conversion, and differentiation. The status monitoring device according to claim 8. 　 A condition monitoring device that monitors the state of a pump based on a detection signal output from only one detection coil that detects a change in magnetic flux corresponding to the displacement of the rotor position relative to the stator of the pump motor, The detection coil is Attached to the stator so as to be able to detect the magnetic flux change corresponding to the displacement of the rotor in the radial direction, The detection signal indicating the magnetic flux change is output, An acquisition unit that acquires the aforementioned detection signal over time, A spectrum generation unit performs 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 pre-set for the monitored object and a reference spectrum to be compared with the monitored spectrum, A determination unit that determines whether the state of the monitored target corresponding to the monitoring frequency band is normal or abnormal based on a comparison of the latest monitoring spectrum and the reference spectrum in the monitoring frequency band, Having, Condition monitoring device. 　 A motor comprising a rotor, a stator that rotates the rotor, and a rotating shaft that rotates together with the rotor, A bearing that supports the aforementioned rotating shaft, At least one detection coil for detecting a change in magnetic flux corresponding to the displacement of the rotor's position relative to the stator, A state monitoring device according to claim 1 or 10, which monitors the state of the pump to be monitored based on the detection signal of the detection coil, Having, pump. The computer is made to function as a status monitoring device according to claim 1 or 10. Status monitoring program. 　 A condition monitoring method performed by a condition monitoring device that monitors the state of a pump based on detection signals output from a plurality of detection coils that detect changes in magnetic flux corresponding to the displacement of the rotor position relative to the stator of the pump motor, the condition of the pump being monitored, Multiple detection coils, Attached to the stator so as to be able to detect the magnetic flux change corresponding to the displacement of the rotor in the radial direction, The detection signal indicating the magnetic flux change is output, A pair of detection coils on which the detection signals are synthesized, Includes, The aforementioned status monitoring device is A storage unit that stores at least one monitoring frequency band and a reference spectrum that are pre-set for the monitored target. Equipped with, The aforementioned status monitoring method is: The state monitoring device performs a signal acquisition step of acquiring at least one of the following over time: a first combined signal obtained by combining the detection signals output from a pair of detection coils so as to obtain a difference, and a second combined signal obtained by combining the detection signals output from a pair of detection coils so as to superimpose them. The state monitoring device performs an FFT process on the signal acquired in the signal acquisition step to generate a monitoring spectrum in the monitoring spectrum generation step, The condition monitoring device performs a determination step of determining whether the state of the monitored object corresponding to the monitoring frequency band is normal or abnormal based on a comparison of the latest monitoring spectrum and the reference spectrum in the monitoring frequency band. including, Status monitoring method.

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