Diagnostic device and diagnostic method

Abstract

The present invention addresses the problem of providing a technique whereby diagnosis relating to the state of a bearing can be easily performed. To this end, a monitoring device (200) according to one embodiment of the present invention is provided with: an acquisition unit (2001) that acquires measurement data of the rotational speed of a motor (100); a calculation unit (2003) that extracts a component of a monitoring frequency of the rotational speed of the motor (100) on the basis of the measurement data of the rotational speed of the motor (100) acquired by the acquisition unit (2001); and a diagnosis unit (2004) that performs a diagnosis relating to the state of the bearing (104) of the motor (100) on the basis of the component of the monitoring frequency extracted by the calculation unit (2003).

Description

Technical Field

[0001] The present invention relates to a diagnostic device and the like. Background Art

[0002] Conventionally, techniques for diagnosing the state related to a bearing have been known (see Patent Documents 1 and 2).

[0003] <Prior Art Documents>

[0004] <Patent Documents>

[0005] Patent Document 1: Japanese Patent No. 7040920

[0006] Patent Document 2: Japanese Patent No. 7270773 Summary of the Invention

[0007] <Problems to be Solved by the Invention>

[0008] However, for example, in Patent Document 1, a vibration sensor is required. Therefore, there may be a situation where a high-precision vibration sensor for detecting vibrations in a high-frequency band that generates vibrations of the bearing with high precision is required; as in the case where a rotating device is installed at a high place or in water, etc., depending on the installation location, the installation of the vibration sensor itself is difficult or impossible. In addition, for example, in Patent Document 2, the bearing damage is estimated by focusing on the mutual inductance of the motor. Therefore, it is necessary to set a reference that matches the electrical characteristics of the motor, etc., and as a result, the algorithm may become complex.

[0009] Therefore, in view of the above problems, an object of the present invention is to provide a diagnostic device that can easily perform a diagnosis related to the state of a bearing.

[0010] <Means for Solving the Problems>

[0011] To achieve the above object, in one embodiment of the present invention, a diagnostic device is provided that acquires measurement data of the rotational speed of a rotating device and performs a diagnosis related to the state of the bearing of the rotating device based on the acquired measurement data of the rotational speed.

[0012] In addition, in another embodiment of the present invention, a diagnostic method is provided in which a diagnostic device acquires measurement data of the rotational speed of a rotating device and performs a diagnosis related to the state of the bearing of the rotating device based on the acquired measurement data of the rotational speed.

[0013] <Effects of the Invention>

[0014] According to the above embodiment, a diagnosis related to the state of a bearing can be easily performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a diagram showing a first example of the structure of a monitoring system.

[0016] Figure 2 This is a diagram showing an example of the structure of a bearing.

[0017] Figure 3 This is a diagram showing an example of the structure of a monitoring device.

[0018] Figure 4 This is a functional block diagram showing a first example of the functional structure of a monitoring device.

[0019] Figure 5 This is a diagram showing an example of the state of vibration generated in a motor due to bearing damage and the change in rotational speed.

[0020] Figure 6 This is a diagram showing a specific example of the result of frequency analysis of the rotational speed of a motor.

[0021] Figure 7 This is a flowchart schematically showing a first example of a diagnostic method related to the state of a bearing based on a monitoring device.

[0022] Figure 8 This is a flowchart schematically showing a second example of a diagnostic method related to the state of a bearing based on a monitoring device.

[0023] Figure 9 This is a diagram showing a second example of the structure of a monitoring system.

[0024] Figure 10 This is a functional block diagram showing a second example of the functional structure of a monitoring device.

[0025] Figure 11 This is a diagram showing an example of the prediction result of the time change of the components of the monitoring frequency of the rotational speed of a motor.

[0026] Symbol Explanation

[0027] 1: Monitoring system

[0028] 100: Motor

[0029] 103: Rotating shaft

[0030] 103a, 103b: Rotating shaft parts

[0031] 104: Bearing

[0032] 104a, 104b: Bearings

[0033] 110: Load device

[0034] 120: Speed detector

[0035] 200: Monitoring device

[0036] 300: External device

[0037] 1041: Outer ring

[0038] 1042: Inner ring

[0039] 1043: Rolling element

[0040] 1044: Retainer

[0041] 2001: Acquisition unit

[0042] 2002: Storage unit

[0043] 2003: Arithmetic unit

[0044] 2003A: Average rotational speed arithmetic unit

[0045] 2003B: Monitoring frequency arithmetic unit

[0046] 2003C: Frequency analysis unit

[0047] 2003D: Monitoring frequency component extraction unit

[0048] 2004: Diagnosis unit

[0049] 2005: Notification unit

[0050] 2006: Storage unit

[0051] 2007: Transmission unit

[0052] 2008: Diagnosis reference setting unit

[0053] f ball : Rolling element flaw passing frequency

[0054] f cage : Retainer flaw passing frequency

[0055] f inner : Inner ring flaw passing frequency

[0056] f outer : Outer ring flaw passing frequency

[0057] f r : Rotational frequency. Detailed implementation manners

[0058] Hereinafter, the implementation manners will be described with reference to the drawings.

[0059] [First example of monitoring system]

[0060] Refer to Figures 1 to 3 , and a first example of the monitoring system 1 according to this embodiment will be described. Figure 1 is a diagram showing an example of the monitoring system 1. Figure 2 is a diagram showing an example of the structure of the bearing 104x. Figure 3 is a diagram showing an example of the structure of the monitoring device 200.

[0061] The monitoring system 1 monitors the state of the bearing 104 that supports the rotating shaft 103 of the electric motor 100 so as to be rotatable.

[0062] As Figure 1 shown, the monitoring system 1 includes a rotary electric motor 100, a load device 110, a speed detector 120, a monitoring device 200, and an external device 300.

[0063] The electric motor 100 rotationally drives the load device 110. The electric motor 100 is, for example, an induction motor. In addition, the electric motor 100 may also be a synchronous motor. The electric motor 100 includes: a rotor 101 disposed at the radial center; a stator 102 disposed to face the rotor 101 on the outer side in the radial direction of the rotor 101; a rotating shaft 103; and a bearing 104.

[0064] The rotating shaft 103 includes a rotating shaft portion 103a at one end connected to the load device 110 in the axial direction of the electric motor 100, and a rotating shaft portion 103b at the other end on the opposite side thereof.

[0065] The bearing 104 supports the rotating shaft 103 so as to be rotatable on the housing of the fixed portion of the electric motor 100. The bearing 104 includes a bearing 104a that supports the rotating shaft portion 103a, and a bearing 104b that supports the rotating shaft portion 103b. Hereinafter, any one of the bearings 104a and 104b may be collectively referred to as the bearing 104x.

[0066] As Figure 2 shown, the bearing 104x includes an outer ring 1041, an inner ring 1042, rolling elements 1043, and a retainer 1044.

[0067] In addition, Figure 2 , a deep groove ball bearing is illustrated as the bearing 104x, but other types of bearings such as tapered roller bearings may also be used.

[0068] The load device 110 is driven by the electric motor 100. The load device 110 is, for example, factory machinery or production equipment.

[0069] The speed detector 120 detects the rotational speed of the electric motor 100 and outputs a signal (rotational speed signal) 130 representing the rotational speed. The speed detector 120 is, for example, a rotary encoder or a resolver. The rotational speed signal 130 is taken into the monitoring device 200 via a given communication line. The given communication line is, for example, a one-to-one communication line or a local area network (LAN) in a factory or the like.

[0070] Based on the rotational speed signal 130 taken in from the speed detector 120, the monitoring device 200 monitors the state of the bearing 104.

[0071] The monitoring device 200 is, for example, a terminal device, a PLC (Programmable Logic Controller), an edge controller, an edge server, etc. installed inside or within the same site of the factory where the electric motor 100 and the load device 110 are installed. In addition, the monitoring device 200 may be built into a power conversion device such as an inverter device or a servo amplifier that supplies power to and drives the electric motor 100. In this case, the function of the monitoring device 200 may be integrated with the control circuit that controls the power conversion device, or may be built into the power conversion device separately from the control circuit. In addition, the monitoring device 200 may be a local server or a cloud server of a monitoring center installed at a location different from the site of the factory where the electric motor 100 and the load device 110 are installed.

[0072] The function of the monitoring device 200 is implemented by any hardware, or a combination of any hardware and software. For example, as Figure 3 shown, the monitoring device 200 includes an external interface 201, an auxiliary storage device 202, a memory device 203, a CPU 204, a high-speed arithmetic device 205, a communication interface 206, an input device 207, a display device 208, and a sound output device 209. These structural elements are connected by a bus BS2.

[0073] The external interface 201 functions as an interface for reading data from or writing data to the recording medium 201A. The recording medium 201A includes, for example, a floppy disk, a CD (Compact Disc), a DVD (Digital Versatile Disc), a BD (Blu-ray (registered trademark) Disc), an SD memory card, a USB memory, etc. Thereby, the monitoring device 200 can read various data used in processing through the recording medium 201A, save them to the auxiliary storage device 202, or install programs for implementing various functions.

[0074] In addition, the monitoring device 200 can also obtain various data or programs used in the processing from an external device (such as the external device 300) through the communication interface 206.

[0075] The auxiliary storage device 202 stores various installed programs and also stores files, data, etc. required for various processes. The auxiliary storage device 202 includes, for example, an HDD (Hard Disc Drive), an SSD (Solid State Disc), a flash memory, etc.

[0076] When an instruction to start a program is given, the memory device 203 reads out the program from the auxiliary storage device 202 and stores it. The memory device 203 includes, for example, a DRAM (Dynamic Random Access Memory) and an SRAM (Static Random Access Memory).

[0077] The CPU 204 executes various programs loaded from the auxiliary storage device 202 into the memory device 203 and implements various functions related to the monitoring device 200 according to the programs.

[0078] The high-speed arithmetic device 205 cooperates with the CPU 204 to perform arithmetic processing at a relatively high speed. The high-speed arithmetic device 205 includes, for example, a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), etc.

[0079] In addition, the high-speed arithmetic device 205 can also be omitted according to the speed of the required arithmetic processing.

[0080] The communication interface 206 is used as an interface for communicably connecting to an external device. Thus, the monitoring device 200 can communicate with external devices of the monitoring device 200, such as the speed detector 120 or the external device 300, through the communication interface 206. In addition, the communication interface 206 can also have various types of communication interfaces according to the communication method with the connected device, etc.

[0081] The input device 207 receives various inputs from the user.

[0082] The input device 207 includes, for example, an input device (hereinafter referred to as "mechanical input device") that accepts mechanical operation inputs from the user. The mechanical input device includes, for example, buttons, toggle keys, levers, keyboards, mice, touch panels installed on the display device 208, touch pads provided separately from the display device 208, and the like.

[0083] In addition, the input device 207 may also include a voice input device that can accept voice inputs from the user. The voice input device includes, for example, a microphone that can collect the user's voice.

[0084] In addition, the input device 207 may also include a gesture input device that can accept gesture inputs from the user. The gesture input device includes, for example, a camera that can capture the state of the user's gestures.

[0085] In addition, the input device 207 may also include a biological input device that can accept biological inputs from the user. The biological input device includes, for example, a camera that can obtain image data containing information related to the user's fingerprint or iris.

[0086] The display device 208 faces the user of the monitoring device 200 and displays an information screen and an operation screen. The display device 208 is, for example, a liquid crystal display or an organic EL (Electroluminescence) display.

[0087] The voice output device 209 faces the user of the monitoring device 200 and conveys various information by voice. The voice output device 209 is, for example, a buzzer, an alarm, a speaker, or the like.

[0088] The external device 300 is provided separately from the monitoring device 200 and is communicably connected to the monitoring device 200 via a given communication line. The external device 300 is, for example, a terminal device or a server device for managing the motors 100 that are dispersedly arranged in multiple factories.

[0089] The external device 300, for example, sends information (external information 310) required for the monitoring device 200 to monitor the state related to the bearing 104 to the monitoring device 200.

[0090] The external information 310 includes information related to the specifications of the bearing 104x (bearing specification information). For example, the specifications of the bearing 104x include, for example, the diameter (rolling element diameter) d of the rolling elements 1043, the pitch circle diameter D of the rolling elements 1043 disposed between the outer ring 1041 and the inner ring 1042, the contact angle α of the rolling elements 1043, and the number (number of rolling elements) Z of the rolling elements 1043. In addition, the external information 310 includes information related to the criteria for diagnosing the state of the bearing 104 (diagnostic criterion information). Information related to the criteria for determining the state of the bearing 104 includes, for example, information on thresholds for diagnosing the presence or absence of abnormalities in the bearing 104, etc.

[0091] In addition, the functions of the external device 300 can also be integrated into the monitoring device 200. That is, information corresponding to the external information 310 can be pre-registered in the monitoring device 200. In this case, the external device 300 can be omitted.

[0092] [First example of the functional structure of the monitoring device]

[0093] Next, with reference to Figures 4 to 6 , a first example of the functional structure of the monitoring device 200 according to the present embodiment will be described.

[0094] Figure 4 is a functional block diagram showing a first example of the functional structure of the monitoring device 200. Figure 5 is a diagram illustrating an example of the state of vibration and change in rotational speed generated in the motor 100 due to damage to the bearing 104x. Specifically, Figure 5 is a diagram illustrating the state of vibration and change in rotational speed generated in the motor 100 when damage DP such as scratches or peeling occurs in a circumferential portion of the contact surface of the inner ring 1042 of the bearing 104x with the rolling elements 1043. Figure 5 includes Figure 5 A to Figure 5 C. Figure 5 A schematically shows the operation of the bearing 104x accompanying the rotation of the motor 100, Figure 5 B shows the time change of the vibration state of the motor 100 accompanying the operation of the bearing 104x, Figure 5 C shows the time change of the rotational speed of the motor 100 accompanying the operation of the bearing 104x. Figure 6 is a diagram showing a specific example of the result of frequency analysis of the rotational speed of the motor 100. Figure 6 includes Figure 6 A to Figure 6 C. Figure 6 A shows an example of the frequency spectrum of the rotational speed of the motor 100 when the bearing 104 is normal. Figure 6B shows an example of the spectrum of the rotational speed of the motor 100 when damage has occurred in a circumferential part of the contact surface of the inner ring 1042 of the bearing 104x with the rolling elements 1043. Figure 6 C shows an example of the spectrum of the rotational speed of the motor 100 when damage has occurred in a circumferential part of the contact surface of the outer ring 1041 of the bearing 104x with the rolling elements 1043.

[0095] As Figure 4 shown, the monitoring device 200 includes an acquisition unit 2001, a storage unit 2002, an arithmetic unit 2003, a diagnosis unit 2004, and a notification unit 2005 as functional units. The functions of the acquisition unit 2001, the arithmetic unit 2003, the diagnosis unit 2004, and the notification unit 2005 are realized, for example, by loading a program installed in the auxiliary storage device 202 into the memory device 203 and executing it on the CPU 204. In addition, the function of the storage unit 2002 is realized, for example, by a specified storage area in the auxiliary storage device 202 or a storage device connected to the monitoring device 200.

[0096] The acquisition unit 2001 acquires information necessary for monitoring related to the state of the bearing 104.

[0097] For example, the acquisition unit 2001 acquires external information 310 received from an external device 300 through the communication interface 206.

[0098] In addition, the acquisition unit 2001 acquires measurement data (rotational speed data) of the rotational speed of the motor 100 based on the rotational speed signal received from the speed detector 120 through the communication interface 206.

[0099] In the storage unit 2002, external information 310 for diagnosing the state related to the bearing 104 is stored.

[0100] The arithmetic unit 2003 performs various operations based on the rotational speed data of the motor 100 acquired by the acquisition unit 2001, and outputs a feature quantity related to the state of the bearing 104.

[0101] For example, the arithmetic unit 2003 includes an average rotational speed arithmetic unit 2003A, a monitoring frequency arithmetic unit 2003B, a frequency analysis unit 2003C, and a monitoring frequency component extraction unit 2003D.

[0102] The average rotational speed arithmetic unit 2003A calculates the average rotational speed of the motor 100 during a certain period based on the rotational speed data for a certain period acquired by the acquisition unit 2001.

[0103] The monitoring frequency calculation unit 2003B calculates the monitoring frequency, which is the frequency of the rotational speed of the motor 100 to be monitored for diagnosing the state of the bearing 104.

[0104] For example, as Figure 5 shown in A, when there is a damage DP in a circumferential part of the contact surface of the inner ring 1042 with the rolling element 1043, as the inner ring 1042 rotates and the rolling element 1043 revolves with the rotation of the rotating shaft 103, the rolling element 1043 passes through the damaged DP part. Thus, as Figure 5 shown in B, vibration is generated, and due to the influence of this vibration, the rotational speed of the motor 100 fluctuates. The period during which the rolling element 1043 passes through the damaged DP part of the inner ring 1042, that is, the period during which the rotational speed of the motor 100 fluctuates due to the damage DP of the inner ring 1042, is determined by the rotational speed of the motor 100 and the specifications related to the structure of the bearing 104x. The frequency (inner ring scar passing frequency) f corresponding to this period inner is expressed by the following formula (1) using the rotational frequency f of the motor 100 r and the rolling element diameter d, pitch circle diameter D, contact angle α, and number of rolling elements Z of the bearing 104x.

[0105]

Formula 1

[0106]

[0107] In addition, when there are damages such as scars or spalls in a circumferential part of the contact surface of the outer ring 1041 with the rolling element 1043, as the outer ring 1041 rotates and the rolling element 1043 revolves with the rotation of the rotating shaft 103, the rolling element 1043 passes through the damaged part. Thus, vibration is generated, and due to its influence, the rotational speed of the motor 100 fluctuates. The period during which the rolling element 1043 passes through the damaged part of the outer ring 1041, that is, the period during which the rotational speed of the motor 100 fluctuates due to the damage of the outer ring 1041, is determined by the rotational speed of the motor 100 and the specifications related to the structure of the bearing 104x. The frequency (outer ring scar passing frequency) f corresponding to this period outer is expressed by the following formula (2) using the rotational frequency f of the motor 100 r and the rolling element diameter d, pitch circle diameter D, contact angle α, and number of rolling elements Z of the bearing 104x.

[0108]

Formula 2

[0109]

[0110] In addition, when there are damages such as scars or peeling on the rolling elements 1043, as the rotary shaft 103 rotates, the rolling elements 1043 rotate on their own axes. As a result, the damaged parts of the rolling elements 1043 pass through the outer ring 1041 and the inner ring 1042. Thereby, vibrations are generated, and due to this influence, the rotational speed of the motor 100 fluctuates. The period during which the damaged parts of the rolling elements 1043 pass through the outer ring 1041 and the inner ring 1042, that is, the period during which the rotational speed of the motor 100 fluctuates due to the damage of the rolling elements 1043, is determined by the rotational speed of the motor 100 and the specifications related to the structure of the bearing 104. The frequency (rolling element scar passing frequency) f corresponding to this period ball uses the rotational frequency f of the motor 100 r and the rolling element diameter d, pitch circle diameter D, contact angle α, and number of rolling elements Z of the bearing 104x, and is expressed by the following formula (3).

[0111]

Formula 3

[0112]

[0113] In addition, when there are damages such as scars or defects on the cage 1044, as the rotary shaft 103 rotates, the cage 1044 rotates (revolves), and as a result, the rolling elements 1043 pass through the damaged part of the cage. Thereby, vibrations are generated, and due to this influence, the rotational speed of the motor 100 fluctuates. The period during which the damaged part of the cage 1044 passes through the rolling elements 1043, that is, the period during which the rotational speed of the motor 100 fluctuates due to the damage of the cage 1044, is determined by the rotational speed of the motor 100 and the specifications related to the structure of the bearing 104. The frequency (cage scar passing frequency) f corresponding to this period cage uses the rotational frequency f of the motor 100 r and the rolling element diameter d, pitch circle diameter D, contact angle α, and number of rolling elements Z of the bearing 104x, and is expressed by the following formula (4).

[0114]

Formula 4

[0115]

[0116] Hereinafter, the inner ring scar passing frequency f inner , the outer ring scar passing frequency f outer , the rolling element scar passing frequency f ball and the cage scar passing frequency f cage are collectively referred to as the "scar passing frequency".

[0117] When damage occurs on the contact surface of the inner ring 1042 with the rolling elements 1043, regarding the rotational speed of the motor 100, sometimes at the inner ring scar passing frequency finner A peak is generated at the n-fold component (n: positive integer) of. For example, as Figure 6 shown in FIGS. A and 6B, in this example, peaks appear at the 1-fold component 601 and the 2-fold component 602 of the inner ring flaw passing frequency f inner .

[0118] In addition, when damage occurs at the contact surface of the inner ring 1042 with the rolling element 1043, with respect to the rotational speed of the motor 100, sometimes at the upper sideband wave component and the lower sideband wave component that are offset by an amount corresponding to the rotational frequency f inner with the n-fold component of the inner ring flaw passing frequency component f r as a reference, peaks are generated. For example, as Figure 6 shown in FIGS. A and 6B, in this example, peaks appear at the upper sideband wave component 603 and the lower sideband wave component 604 that are offset from the 1-fold component 601 of the inner ring flaw passing frequency f inner by the rotational frequency f r .

[0119] In addition, when damage occurs at the contact surface of the outer ring 1041 with the rolling element 1043, with respect to the rotational speed of the motor 100, sometimes a peak is generated at the n-fold component of the outer ring flaw passing frequency f outer . For example, as Figure 6 shown in FIGS. A and 6C, in this example, a peak is generated at the 2-fold component 605 of the outer ring flaw passing frequency f outer .

[0120] In addition, when damage occurs at the contact surface of the outer ring 1041 with the rolling element 1043, with respect to the rotational speed of the motor 100, sometimes at the upper sideband wave component and the lower sideband wave component that are offset by an amount corresponding to the rotational frequency f outer with the n-fold component of the outer ring flaw passing frequency f r as a reference, peaks are generated. For example, as Figure 6 shown in FIGS. A and 6C, in this example, peaks appear at the upper sideband wave component 606 and the lower sideband wave component 607 that are offset from the 2-fold component 605 of the outer ring flaw passing frequency f outer by the rotational frequency f r .

[0121] In addition, when damage occurs to the rolling element 1043, with respect to the rotational speed of the motor 100, sometimes a peak is generated at the n-fold component of the rolling element flaw passing frequency f ball . In addition, when damage occurs to the rolling element 1043, sometimes at the upper sideband wave component and the lower sideband wave component that are offset by an amount corresponding to the rotational frequency f ball with the n-fold component of the rolling element flaw passing frequency f r as a reference, peaks are generated.

[0122] In addition, when damage occurs in the retainer 1044, with respect to the rotational speed of the motor 100, sometimes a peak occurs at the n-fold component of the retainer scar passing frequency f cage In addition, when damage occurs in the retainer 1044, sometimes at the n-fold component of the retainer scar passing frequency f cage as a reference, peaks occur at the upper sideband wave component and the lower sideband wave component offset by an amount corresponding to the rotational frequency f r Accordingly.

[0123] Thus, when damage occurs in the bearing 104x, the influence of the damage appears at the n-fold component of the scar passing frequency and the sideband wave component offset by an amount corresponding to the rotational frequency f r Accordingly. Therefore, for example, the monitoring frequency calculation unit 2003B calculates, as the monitoring frequency, at least one of the n-fold component of the scar passing frequency in the range of N1 ≤ n ≤ N2 and the sideband wave component offset by an amount corresponding to the rotational frequency f r Accordingly, with respect to the calculated rotational frequency f

[0124] Specifically, the monitoring frequency calculation unit 2003B calculates the rotational frequency f r of the motor 100 over a certain period calculated by the average rotational speed calculation unit 2003A. Then, based on the calculated rotational frequency f r and the bearing specification information, the monitoring frequency calculation unit 2003B uses the above formulas (1) to (4) to calculate, as the monitoring frequency, the n-fold component of the scar passing frequency or the sideband wave component offset by an amount corresponding to the rotational frequency f r Accordingly.

[0125] The monitoring frequency calculation unit 2003B calculates the monitoring frequency for, for example, the inner ring scar passing frequency f inner , the outer ring scar passing frequency f outer , the rolling element scar passing frequency f ball and the retainer scar passing frequency f cage all. In addition, the monitoring frequency calculation unit 2003B may also calculate the monitoring frequency only for a part of the inner ring scar passing frequency f inner , the outer ring scar passing frequency f outer , the rolling element scar passing frequency f ball and the retainer scar passing frequency f cage Accordingly.

[0126] In addition, when the bearing specification information of the bearings 104a and 104b is different from each other, the monitoring frequency calculation unit 2003B can also calculate the monitoring frequency for each of the bearings 104a and 104b, or can calculate the monitoring frequency only for any one of them.

[0127] The frequency analysis unit 2003C performs a frequency analysis of the rotational speed data for a certain period acquired by the acquisition unit 2001, and outputs data on the spectral distribution of the rotational speed of the motor 100 as an analysis result. For example, the frequency analysis unit 2003C performs an FFT (Fast Fourier Transform) analysis on the rotational speed data for a certain period, and outputs data on the spectral distribution of the rotational speed of the motor 100 as an analysis result.

[0128] The monitoring frequency component extraction unit 2003D extracts the components of the monitoring frequency from the spectral distribution of the analysis result of the frequency analysis unit 2003C.

[0129] The diagnosis unit 2004 performs a diagnosis related to the state of the bearing 104 based on the output of the calculation unit 2003, specifically, based on the components of the monitoring frequency extracted by the monitoring frequency component extraction unit 2003D and the diagnosis reference information.

[0130] The diagnosis related to the state of the bearing 104 includes, for example, a diagnosis related to an abnormality of the bearing 104. Among the abnormalities of the bearing 104, in addition to the suddenly occurring abnormalities, it also includes the deterioration that develops relatively slowly. The diagnosis related to the abnormality of the bearing 104 includes, for example, a diagnosis of the presence or absence of an abnormality of the bearing 104. In addition, the diagnosis related to the abnormality of the bearing 104 can also include a diagnosis of the degree (abnormality degree) of the abnormality of the bearing 104.

[0131] The notification unit 2005 notifies the user of the diagnosis result of the diagnosis unit 2004.

[0132] The notification unit 2005 can notify the user of the diagnosis result regardless of the content of the diagnosis result, or can limit the notification of the diagnosis result to the case where the diagnosis result indicates a defective state of the bearing 104. The case where the diagnosis result indicates that the state of the bearing 104 is a defective state is, for example, the case where the diagnosis result indicates that the bearing 104 has an abnormality, the case where the diagnosis result indicates that the abnormality degree of the bearing 104 is relatively high with respect to a given reference, and the case where the diagnosis result indicates that there are signs of an abnormality of the bearing 104.

[0133] The notification unit 2005 notifies the user of the diagnosis result through, for example, the display device 208 and the sound output device 209. In addition, the notification unit 2005 may also notify the user of the diagnosis result through an indicator attached to the load device 110 or the motor 100. In this case, the notification unit 2005 outputs a notification instruction including the diagnosis result to the indicator of the load device 110 or the motor 100 through the communication interface 206. In addition, the notification unit 2005 may also output the diagnosis result outside the monitoring device 200 so that the diagnosis result can be confirmed on a terminal device (user terminal) used by the user. For example, the notification unit 2005 sends the diagnosis result to the portable terminal (such as a smart phone or a tablet terminal) used by the user through push notification via the communication interface 206. In addition, the notification unit 2005 may also send the diagnosis result to the user's email address or the account of the SNS (Social Networking Service).

[0134] In this way, in this example, the monitoring device 200 can perform diagnosis related to the state of the bearing 104 based on the rotational speed data of the motor 100. Thus, for example, it is not necessary to add a dedicated vibration sensor or the like for the diagnosis related to the state of the bearing 104, and the speed detector 120 used for the control of the motor 100 can be used in combination. Therefore, the monitoring system 1 can easily implement the diagnosis related to the state of the bearing 104, and as a result, the cost for the diagnosis function can be reduced.

[0135] In addition, since the rotational speed of the motor 100 changes every time vibration accompanied by an abnormality of the bearing 104 occurs, in this example, the monitoring system 1 can achieve the detection sensitivity of the change in the state of the bearing 104 at the same level as in the case of using a vibration sensor.

[0136] In addition, for example, when performing diagnosis related to the state of the bearing 104 using a vibration sensor, the accuracy of the diagnosis may be reduced due to the influence of interference vibration or resonance. In addition, for example, although there is a prior art that uses the electrical characteristic quantity of the motor 100 to perform diagnosis related to the state of the bearing 104, the accuracy of the diagnosis may be reduced due to the influence of the current high-order harmonic noise of the inverter.

[0137] In contrast, in this example, without being affected by interference vibration or resonance and high-order harmonic noise, the monitoring system 1 can perform the diagnosis related to the state of the bearing 104 more appropriately.

[0138] In addition, for example, when diagnosing the state of the bearing 104 using the electrical characteristic quantities of the electric motor 100, it is necessary to set diagnosis parameters and diagnosis criteria (such as thresholds) according to the electrical characteristics of the electric motor 100, which may complicate the algorithm.

[0139] In contrast, in this example, only the specifications related to the structure of the bearing 104 need to be considered, and the setting of the diagnosis criteria can be simplified. Therefore, from this perspective, the monitoring system 1 can also easily implement the diagnosis related to the state of the bearing 104.

[0140] [First Example of Diagnosis Method Related to State of Bearing]

[0141] Next, with reference to Figure 7 , a first example of the diagnosis method related to the state of the bearing 104 will be described.

[0142] Figure 7 is a flowchart schematically showing a first example of the diagnosis method related to the state of the bearing 104.

[0143] This flowchart is executed, for example, every given processing cycle during the operation of the electric motor 100.

[0144] As Figure 7 shown, in step S102, the acquisition unit 2001 acquires the rotational speed data of the electric motor 100 based on the latest rotational speed signal 130 for a certain period taken in from the speed detector 120.

[0145] When the processing of step S102 is completed, the monitoring device 200 proceeds to step S104.

[0146] In step S104, the average rotational speed calculation unit 2003A calculates the average rotational speed of the electric motor 100 during the latest certain period based on the latest rotational speed data for a certain period obtained by the processing of step S102.

[0147] When the processing of step S104 is completed, the monitoring device 200 proceeds to step S106.

[0148] In step S106, the monitoring frequency calculation unit 2003B calculates the monitoring frequency based on the calculation result of the processing in step S104 and the bearing specification information in the storage unit 2002.

[0149] When the processing of step S106 is completed, the monitoring device 200 proceeds to step S108.

[0150] In step S108, the frequency analysis unit 2003C performs frequency analysis on the rotational speed data for the latest fixed period obtained in step S102 and outputs the spectrum data.

[0151] When the processing of step S108 is completed, the monitoring device 200 proceeds to step S110.

[0152] In step S110, the monitoring frequency component extraction unit 2003D extracts the monitoring frequency components from the spectrum distribution data of the analysis result in step S108 based on the operation result of step S106.

[0153] When the processing of step S110 is completed, the monitoring device 200 proceeds to step S112.

[0154] In step S112, the diagnosis unit 2004 calculates the sum value SUM of the amplitude values of all the monitoring frequency components extracted in step S110.

[0155] When the processing of step S112 is completed, the monitoring device 200 proceeds to step S114.

[0156] In step S114, the diagnosis unit 2004 determines whether the sum value SUM calculated in step S112 is equal to or greater than the threshold value SUMth. The threshold value SUMth is pre-stored in the storage unit 2002 as diagnostic reference information. When the sum value SUM is equal to or greater than the threshold value SUMth, the diagnosis unit 2004 diagnoses that the bearing 104 is abnormal and proceeds to step S116. In other cases, it diagnoses that the bearing 104 is not abnormal and ends the current flowchart.

[0157] In step S116, the notification unit 2005 notifies the user that the bearing 104 is abnormal.

[0158] When the processing of step S116 is completed, the monitoring device 200 ends the processing of the current flowchart.

[0159] [Second Example of Diagnostic Method Related to Bearing Condition]

[0160] Next, referring to Figure 8 , a second example of the diagnostic method related to the condition of the bearing 104 will be described.

[0161] In this example, the description will focus on the parts different from the above first example, and sometimes the description of the same or corresponding content as the above first example will be omitted.

[0162] Figure 8 is a flowchart schematically showing a second example of the diagnostic method related to the condition of the bearing 104.

[0163] This flowchart is executed every given processing cycle during the operation of the electric motor 100, for example.

[0164] The processes of steps S202, S204, S206, S208, and S210 are the same as the processes of steps S102, S104, S106, S108, and S110 of the above Figure 7 and thus the description thereof is omitted.

[0165] When the process of step S210 is completed, the monitoring device 200 proceeds to step S212.

[0166] In step S212, the diagnostic unit 2004 initializes the counter C to "0".

[0167] When the process of step S212 is completed, the monitoring device 200 proceeds to step S214.

[0168] A series of processes of steps S214, S216, and S218 are performed in a given order for each of the components of a plurality of monitored frequencies extracted by the process of step S210.

[0169] In step S214, the diagnostic unit 2004 determines whether the amplitude A corresponding to the spectral value of the component of the monitored frequency of the object is equal to or greater than the threshold value Ath. The threshold value Ath is pre-stored in the storage unit 2002 as diagnostic reference information. The threshold value Ath can be the same for all of the components of the plurality of monitored frequencies, or at least some of them can be different from each other. When the amplitude A of the component of the monitored frequency of the object is equal to or greater than the threshold value Ath, the diagnostic unit 2004 proceeds to step S216, and in other cases, proceeds to step S218.

[0170] In step S216, the diagnostic unit 2004 increments the counter C by "1" (C = C + 1).

[0171] When the process of step S216 is completed, the monitoring device 200 proceeds to step S218.

[0172] In step S218, the diagnostic unit 2004 determines whether the determination in step S214 for all of the components of the monitored frequencies has ended. When the determination for all of the components of the monitored frequencies has ended, the diagnostic unit 2004 proceeds to step S220, and when it has not ended, returns to step S214 and performs the processes after step S214 for the next component of the monitored frequency of the object.

[0173] In step S220, the diagnosis unit 2004 determines whether the counter C is equal to or greater than the threshold value Cth. The threshold value Cth is pre-stored in the storage unit 2002 as diagnostic reference information. When the counter C is equal to or greater than the threshold value Cth, the diagnosis unit 2004 diagnoses that there is an abnormality in the bearing 104 and proceeds to step S222. Otherwise, the diagnosis unit 2004 diagnoses that there is no abnormality in the bearing 104 and ends the current flowchart.

[0174] The processing of step S222 is the same as that of step S116 described above Figure 7 and thus will not be described again.

[0175] When the processing of step S222 is completed, the monitoring device 200 ends the current flowchart.

[0176] [Second example of the monitoring system]

[0177] Next, a second example of the monitoring system 1 will be described with reference to Figure 9 .

[0178] In this example, the same or corresponding structures as those in the above first example ( Figure 1 ) are labeled with the same reference numerals, and the description will focus on the differences from the above first example.

[0179] As Figure 9 shown, the difference between this example and the above first example is that data (monitoring frequency component data) 320 regarding the monitoring frequency of the rotational speed data is sent from the monitoring device 200 to the external device 300.

[0180] The monitoring device 200, for example, sends the monitoring frequency component data 320 to the external device 300 each time it extracts the spectral value (amplitude value) of the monitoring frequency of the rotational speed of the motor 100 based on the latest rotational speed data for a certain period.

[0181] The external device 300 accumulates, for example, the history of the monitored frequency component data 320. Thereby, the external device 300 can analyze the temporal change of the components of the monitored frequency and predict future changes. For example, the external device 300 applies known statistical methods to generate a prediction model of the change of the monitored frequency component based on the history of the data of the monitored frequency components of the plurality of motors 100. In addition, the external device 300 may also use the history of the data of the monitored frequency components of the plurality of motors 100 as teacher data for supervised learning to generate a learned complete model for predicting the change of the monitored frequency component. Therefore, the external device 300 can distribute, for example, the prediction model for predicting the change of the monitored frequency component as the external information 310, or distribute the prediction result of the future change of the monitored frequency component as the external information 310 to the monitoring device 200.

[0182] [Second Example of the Functional Structure of the Monitoring Device]

[0183] Next, with reference to Figure 10 、 Figure 11 , a second example of the functional structure of the monitoring device 200 according to the present embodiment will be described.

[0184] In this example, the same or corresponding structures as those in the above first example ( Figure 4 ) are denoted by the same reference numerals, and the description will focus on the parts different from the above first example.

[0185] Figure 10 is a functional block diagram showing a second example of the functional structure of the monitoring device 200. Figure 11 is a diagram showing an example of the prediction result of the temporal change of the monitored frequency component of the rotational speed of the motor.

[0186] As Figure 10 shown, in this example, the difference from the above first example is that the monitoring device 200 includes a storage unit 2006, a transmission unit 2007, and a diagnostic reference setting unit 2008 as functional units.

[0187] In the storage unit 2006, the data of the monitored frequency components extracted by the monitored frequency component extraction unit 2003D is stored in a time-series accumulation manner.

[0188] The transmission unit 2007 sends the data of the monitored frequency components stored in the storage unit 2006 to the external device 300 through the communication interface 206. The transmission unit 2007 can send the data to the external device 300 each time new data of the monitored frequency components is saved in the storage unit 2006, or can send the data that is new compared to the previously sent part to the external device 300 through batch processing.

[0189] The diagnostic criterion setting unit 2008 sets diagnostic criteria for diagnosing based on the diagnosis related to the state of the bearing 104 by the diagnostic unit 2004.

[0190] For example, the diagnostic criterion setting unit 2008 sets a threshold value (such as the above-mentioned threshold value SUMth or threshold value Ath) for diagnosing the presence or absence of an abnormality in the bearing 104 based on the data of the component of the monitoring frequency in the initial state of the motor 100 stored in the storage unit 2006. The so-called initial state refers to, for example, the first operation after the motor 100 is shipped from the factory. Thus, the diagnostic unit 2004 can set diagnostic criteria such as threshold values according to the mechanical characteristics of each motor 100.

[0191] The acquisition unit 2001 acquires, for example, information (prediction result information) on the prediction result of the change in the component of the monitoring frequency of the rotational speed of the motor 100 as the external information 310. In addition, the acquisition unit 2001 may acquire a prediction model of the change in the component of the monitoring frequency of the rotational speed of the motor 100 from the external device 300 as the external information 310.

[0192] The prediction result information or the prediction model is stored in the storage unit 2002.

[0193] The diagnostic unit 2004 diagnoses, for example, in the same manner as the above first example, the presence or absence of an abnormality in the bearing 104 and the degree of the abnormality.

[0194] In addition, in this example, the diagnostic unit 2004 may also use the prediction result information or the prediction model to diagnose the remaining life of the bearing 104 or the presence or absence of a sign of an abnormality in the bearing 104.

[0195] For example, as Figure 11 shown, in this example, based on the time-series measurement data 1101 of the sum value SUM of the amplitude values of all the monitoring frequency components up to the current (time Tc), prediction data 1102 of the time change of the sum value SUM after the current is obtained.

[0196] The diagnostic unit 2004 can calculate the timing (time Td) when the threshold value SUMth reaches the threshold value SUMth according to the relationship between the prediction data 1102 and the threshold value SUMth. Therefore, the diagnostic unit 2004 can estimate the difference between the times Td and Tc as the remaining life of the bearing 104.

[0197] In addition, the diagnostic unit 2004 may also be the same as the second example of the above diagnostic method ( Figure 9)Similarly, based on the prediction data of the amplitude A of the components for each monitoring frequency, the remaining life is predicted. For example, the diagnosis unit 2004 predicts the remaining life for the components of each monitoring frequency and adopts, such as, the average value or the minimum value thereof as the remaining life of the bearing 104.

[0198] In addition, the diagnosis unit 2004 can also diagnose the presence or absence of signs of abnormality of the bearing 104 based on the rising slope of the prediction data 1102 of the time variation of the sum value SUM. Specifically, this is because when the rising slope of the prediction data 1102 of the time variation of the sum value SUM is relatively large with respect to a given reference, the diagnosis unit 2004 can reliably consider that the sum value SUM exceeds the threshold value SUMth.

[0199] In addition, the diagnosis unit 2004 can also, Figure 9 similar to the second example of the above diagnosis method, diagnose the presence or absence of signs of abnormality of the bearing 104 based on the prediction data of the amplitude A of the components for each monitoring frequency. For example, the diagnosis unit 2004 uses, such as, the average value or the maximum value of the rising slope of the prediction data of the amplitude A of the components for each monitoring frequency to diagnose the presence or absence of signs of abnormality of the bearing 104.

[0200] Thus, in this example, the monitoring system 1 can record the data of the components of the monitoring frequency of the rotational speed of the motor 100. Therefore, for example, the monitoring device 200 can use the data of the initial state of the motor 100 to set a diagnosis reference for diagnosing the state related to the bearing 104. As a result, the diagnosis reference can be set to match the individual mechanical characteristics of the motor 100.

[0201] In addition, in this example, the monitoring system 1 can predict the future time variation of the components of the monitoring frequency based on the history of the data of the components of the monitoring frequency of the rotational speed of the motor 100. Therefore, the monitoring system 1 can diagnose the remaining life of the bearing 104 or diagnose the presence or absence of signs of abnormality of the bearing 104.

[0202] [Other Embodiments]

[0203] Next, other embodiments will be described.

[0204] The above embodiments can be appropriately deformed or changed.

[0205] For example, in the above embodiments, the diagnosis unit 2004 can also, instead of the sum value SUM of the amplitudes A of the components of the monitoring frequency of the rotational speed of the motor 100, perform the diagnosis related to the state of the bearing 104 based on, such as, the maximum value or the average value of the amplitude A.

[0206] In addition, in the above-described embodiment or an example of its modification / variation, the functions of the external device 300 may also be integrated into the monitoring device 200.

[0207] In addition, in the above-described embodiment or an example of its modification / variation, the monitoring device 200 may also use, instead of frequency analysis, a filter or the like that extracts the component of the monitoring frequency of the rotational speed of the motor 100, thereby extracting the component of the monitoring frequency of the rotational speed of the motor 100.

[0208] In addition, in the above-described embodiment or an example of its modification / variation, the monitoring device 200 may also perform diagnosis related to the state of the bearing 104 based on time-series waveform data, using a known analysis method such as waveform counting, instead of the frequency component of the rotational speed of the motor 100.

[0209] In addition, in the above-described embodiment or an example of its modification / variation, the monitoring device 200 may also perform diagnosis related to the state of the bearing of the load device 110, instead of or in addition to the bearing 104 of the motor 100.

[0210] In addition, the same diagnostic method as in the above-described embodiment or an example of its modification / variation can also be used for diagnosis related to the state of the bearing of other rotating devices of a type different from the motor 100 or the load device 110.

[0211] [Operation]

[0212] Next, the operation of the diagnostic device, diagnostic method, and program according to the present embodiment will be described.

[0213] In the first mode of the present embodiment, the diagnostic device acquires measurement data of the rotational speed of the rotating device, and performs diagnosis related to the state of the bearing of the rotating device based on the acquired measurement data of the rotational speed. The diagnostic device is, for example, the above-described monitoring device 200. The rotating device is, for example, the above-described motor 100. The bearing is, for example, the above-described bearing 104.

[0214] In addition, in the first mode of the present embodiment, the following diagnostic method may also be executed: the diagnostic device acquires measurement data of the rotational speed of the rotating device, and performs diagnosis related to the state of the bearing of the rotating device based on the acquired measurement data of the rotational speed.

[0215] In addition, in the first mode of the present embodiment, a program may also be adopted, which causes the information processing device to acquire measurement data of the rotational speed of the rotating device, and to perform diagnosis related to the state of the bearing of the rotating device based on the acquired measurement data of the rotational speed. The information processing device is, for example, the above-described monitoring device 200.

[0216] Thus, a diagnostic device or an information processing device (hereinafter referred to as "diagnostic device etc.") can easily perform a diagnosis related to the state of the bearing of the rotating device by using the measurement data of the rotational speed of the rotating device.

[0217] In addition, in the second mode of the present embodiment, on the premise of the above first mode, the diagnostic device etc. can also perform a diagnosis related to the state of the bearing based on the frequency components of the acquired measurement data of the rotational speed.

[0218] Thus, the diagnostic device etc. can perform a diagnosis related to the state of the bearing of the rotating device based on the frequency components of the measurement data of the rotational speed.

[0219] In addition, in the third mode of the present embodiment, on the premise of the above second mode, the diagnostic device etc. can also perform a diagnosis related to the state of the bearing based on the result of the frequency analysis of the acquired measurement data of the rotational speed.

[0220] Thus, the diagnostic device etc. can perform a diagnosis related to the state of the bearing of the rotating device based on the frequency components of the measurement data of the rotational speed obtained from the result of the frequency analysis of the measurement data of the rotational speed.

[0221] In addition, in the fourth mode of the present embodiment, on the premise of the above second or third mode, the diagnostic device etc. can also perform a diagnosis related to the state of the bearing based on the frequency components of the monitoring object associated with a specific frequency indicating the damage of the bearing. The frequency components of the monitoring object are, for example, the components of the above monitoring frequency.

[0222] Thus, the diagnostic device etc. can focus on the possible damage in the bearing of the rotating device to perform a diagnosis related to the state of the bearing.

[0223] In addition, in the fifth mode of the present embodiment, on the premise of the above fourth mode, the specific frequency may also include at least one of a first frequency corresponding to the vibration generated in the rotating device due to the damage occurring in the inner ring of the bearing, a second frequency corresponding to the vibration generated in the rotating device due to the damage occurring in the outer ring of the bearing, a third frequency corresponding to the vibration generated in the rotating device due to the damage occurring in the rolling element of the bearing, and a fourth frequency corresponding to the vibration generated in the rotating device due to the damage occurring in the cage of the bearing. The first frequency is, for example, the above-mentioned inner ring scar passing frequency f inner . The second frequency is, for example, the above-mentioned outer ring scar passing frequency f outer . The third frequency is, for example, the above-mentioned rolling element scar passing frequency f ballIn addition, the fourth frequency is, for example, the frequency f at which the retainer flaw described above occurs. cage .

[0224] Accordingly, a diagnostic device or the like can perform diagnosis related to the state of the bearing by focusing on damage that may occur in at least one of the inner ring, outer ring, rolling elements, and retainer of the bearing of the rotating device.

[0225] In addition, in the sixth aspect of the present embodiment, on the premise of the fifth aspect described above, the first frequency, the second frequency, the third frequency, and the fourth frequency may also be defined based on the rotational frequency of the rotating device and the dimensional specifications of the bearing.

[0226] Accordingly, a diagnostic device or the like can easily determine a specific frequency indicating damage to the bearing. As a result, diagnosis related to the state of the bearing can be easily performed based on the frequency components of the monitoring target.

[0227] In addition, in the seventh aspect of the present embodiment, on the premise of any one of the fourth to sixth aspects described above, the frequency components of the monitoring target may also include at least one of a multiple component of the specific frequency and a sideband wave component that is offset by an amount corresponding to the rotational frequency of the rotating device with respect to the multiple component of the specific frequency.

[0228] Accordingly, a diagnostic device or the like can perform diagnosis related to the state of the bearing based on a multiple component of a specific frequency indicating damage to the bearing or a change in which a sideband wave component offset by an amount corresponding to the rotational frequency appears from the multiple component.

[0229] In addition, in the eighth aspect of the present embodiment, on the premise of any one of the fourth to seventh aspects described above, a diagnostic device or the like may also perform diagnosis related to an abnormality of the bearing based on the amplitude value of the frequency components of the monitoring target.

[0230] Accordingly, a diagnostic device or the like can perform diagnosis related to the state of the bearing of the rotating device based on the amplitude value (spectral value) of the frequency components of the monitoring target.

[0231] In addition, in the ninth aspect of the present embodiment, on the premise of the eighth aspect described above, a diagnostic device or the like may also diagnose that the bearing is abnormal when the amplitude value of the frequency components of the monitoring target is relatively higher than a given reference. The given reference is, for example, the above-described threshold Ath and threshold SUMth.

[0232] Accordingly, a diagnostic device or the like can diagnose whether there is an abnormality in the bearing of the rotating device.

[0233] In addition, in the tenth mode of the present embodiment, on the premise of the above-mentioned eighth mode, diagnosis related to the remaining life or abnormal signs of the bearing may also be performed based on the history of the amplitude values of the frequency components of the object to be monitored.

[0234] Thereby, a diagnostic device or the like can perform diagnosis related to the remaining life or abnormal signs of the bearing of the rotating device.

[0235] In addition, in the eleventh mode of the present embodiment, on the premise of any one of the above-mentioned first to tenth modes, a diagnostic device or the like may also notify the user of the diagnostic result related to the state of the bearing.

[0236] Thereby, a diagnostic device or the like can notify the user of the diagnostic result related to the state of the bearing of the rotating device.

[0237] As described above, the embodiments have been described in detail. The present invention is not limited to these specific embodiments, and various modifications / changes can be made within the scope of the gist described in the claims.

Claims

1. A diagnostic device, wherein: The diagnostic device acquires measurement data of a rotation speed of a rotating device, and performs diagnosis on a state of a bearing of the rotating device based on the acquired measurement data of the rotation speed.

2. The diagnostic device according to claim 1, wherein: The diagnostic device performs diagnosis on the state of the bearing based on the frequency component of the acquired measurement data of the rotation speed.

3. The diagnostic device according to claim 2, wherein: The diagnostic device performs diagnosis on the state of the bearing based on a result of frequency analysis of the acquired rotational speed measurement data.

4. The diagnostic device according to claim 2 or 3, wherein: The diagnostic device performs diagnosis on the state of the bearing based on a frequency component of a monitoring target associated with a specific frequency indicating damage to the bearing.

5. The diagnostic device according to claim 4, wherein: The specific frequency includes at least one of a first frequency, a second frequency, a third frequency and a fourth frequency, the first frequency being a frequency corresponding to the vibration generated in the rotating device due to damage in the inner ring of the bearing, the second frequency being a frequency of the vibration generated in the rotating device due to damage in the outer ring of the bearing, the third frequency being a frequency corresponding to the vibration generated in the rotating device due to damage in the rolling element of the bearing, and the fourth frequency being a frequency corresponding to the vibration generated in the rotating device due to damage in the retainer of the bearing.

6. The diagnostic device according to claim 5, wherein: The first frequency, the second frequency, the third frequency, and the fourth frequency are specified based on the rotation frequency of the rotating device and the size specifications of the bearing.

7. The diagnostic device according to claim 4, wherein: The frequency component to be monitored includes at least one of a multiple component of the specific frequency and a sideband wave component that is offset by an amount corresponding to the rotation frequency of the rotating device with respect to the multiple component of the specific frequency.

8. The diagnostic device according to claim 4, wherein: The diagnostic device performs diagnosis related to abnormality of the bearing based on an amplitude value of a frequency component of the monitoring target.

9. The diagnostic device according to claim 8, wherein: The diagnostic device diagnoses that an abnormality exists in the bearing when an amplitude value of the frequency component of the monitoring target is higher than a predetermined reference.

10. The diagnostic device according to claim 8, wherein: The diagnostic device performs diagnosis on the remaining life of the bearing or a sign of abnormality based on the history of the amplitude value of the frequency component of the monitoring target.

11. The diagnostic device according to any one of claims 1 to 3, wherein: The diagnostic device notifies a user of a diagnostic result related to the state of the bearing.

12. A diagnostic method, wherein: The diagnostic device acquires measurement data of a rotation speed of a rotating device, and performs diagnosis on a state of a bearing of the rotating device based on the acquired measurement data of the rotation speed.

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