Diagnostic device

Abstract

To provide a diagnostic device capable of properly performing abnormality diagnosis by vibration.SOLUTION: A vibration determination reference value calculation means 6 of a diagnostic main device 2 calculates a vibration determination reference value (for example, a vibration level indicating the magnitude of vibration) based on the measurement output of an acceleration sensor. An abnormality determination means 8 determines abnormality when the vibration determination reference value exceeds a set upper limit threshold value for a predetermined time. In addition, it is determined that there is an abnormality in which the base threshold value is exceeded for a predetermined time. Here, the predetermined time at the base threshold value is longer than the predetermined time at the upper limit threshold value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a diagnostic device that measures vibrations of a monitored object such as a device to detect abnormalities in the monitored object. [Background technology]

[0002] Vibrations from equipment that vibrates during operation, such as conveyor belts and manufacturing equipment, are measured, and based on the measurement results, a diagnosis is made as to whether the equipment is operating normally or abnormally. When an abnormality occurs in the operation of the equipment, the vibration increases, and this is used to diagnose whether an abnormality exists.

[0003] For example, a threshold value is determined in advance, and if the detected vibration exceeds this threshold value, it is diagnosed as abnormal.

[0004] Patent Document 1 also discloses the following diagnostic device. The average value of vibrations of a device detected during a first time period, which serves as a reference, is calculated. Similarly, the average value of vibrations of the device detected during a second time period, which is the subject of diagnosis, is calculated. As shown in Figure 12, diagnosis is performed by comparing an average value AV2 during the first time period with an average value AV3 during the second time period. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2023-169717 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the above-described conventional techniques have the following problems.

[0007] First, there was a problem in that the average value could not be calculated and a judgment could not be made until the specified period had elapsed. While the accuracy of the judgment could be increased by lengthening the specified period, this was a trade-off with the speed of the judgment. On the other hand, for example, if a threshold value was determined and a judgment was made using the instantaneous value of vibration, there was a possibility of an erroneous judgment being made due to momentary disturbances.

[0008] Secondly, when a threshold is set and an abnormality is judged when vibration exceeds this threshold, it is possible to respond to large changes in vibration, but it is difficult to detect the early stages of an abnormality where the vibration changes gradually.

[0009] SUMMARY OF THE INVENTION An object of the present invention is to provide a diagnostic device that solves at least one of the above problems and is capable of appropriately diagnosing abnormalities caused by vibrations. [Means for solving the problem]

[0010] The following are some independent features of the present invention, which do not necessarily need to be combined but can be combined in any desired manner.

[0011] (1)-(3) The diagnostic device according to the present invention comprises a vibration sensor that measures vibrations of an object to be monitored, a vibration judgment reference value calculation means that calculates a vibration judgment reference value based on the measurement output of the vibration sensor, an abnormality determination means that determines that the object to be monitored is abnormal not only when the vibration judgment reference value exceeds an upper threshold value for a first predetermined time period continuously, but also when the vibration judgment reference value is below a lower threshold value for a second predetermined time period continuously, and a determination result output means that outputs the determination result of the abnormality determination means.

[0012] An abnormality is determined to exist when the threshold value is continuously exceeded (or fallen below) for a specified period of time, which allows for quick determination and prevents erroneous determinations due to disturbances, etc. In addition, a determination is also made when the value falls below the lower threshold value, so it is possible to determine that an abnormality exists even when vibrations decrease (for example, when the monitored equipment stops).

[0013] (4) The diagnostic device according to the present invention is characterized in that the second predetermined time is equal to the first predetermined time.

[0014] Therefore, whether the vibration increases or decreases, the judgment can be made based on the same criteria.

[0015] (5) The diagnostic device according to the present invention is characterized in that the abnormality determination means determines that the monitored object is abnormal even when the vibration determination reference value exceeds a base threshold value set between the upper threshold value and the lower threshold value for a third predetermined time period.

[0016] Therefore, it is possible to monitor even abnormalities that progress gradually.

[0017] (6) The diagnostic device according to the present invention is characterized in that the abnormality determination means determines that the monitored object is abnormal even when the vibration determination reference value falls below a base threshold value set between the upper threshold value and the lower threshold value for a third predetermined time period.

[0018] Therefore, it is possible to monitor even abnormalities that progress gradually.

[0019] (7) The diagnostic device according to the present invention is characterized in that the upper threshold value and the lower threshold value are set by the threshold value setting means based on a vibration judgment reference value calculated based on the measurement output of the vibration sensor in the teaching mode.

[0020] Therefore, since the threshold value is set based on the actual measurement value, it is possible to set a more appropriate threshold value.

[0021] (8) The diagnostic method of the present invention is a method for diagnosing a monitored object based on its vibration, characterized in that it acquires the vibration of the monitored object, calculates a vibration judgment reference value based on the acquired vibration, and determines that the monitored object is abnormal not only when the vibration judgment reference value exceeds an upper threshold value for a first predetermined time period continuously, but also when the vibration judgment reference value is below a lower threshold value for a second predetermined time period continuously.

[0022] An abnormality is determined to exist when the threshold value is continuously exceeded (or fallen below) for a specified period of time, which allows for quick determination and prevents erroneous determinations due to disturbances, etc. In addition, a determination is also made when the value falls below the lower threshold value, so it is possible to determine that an abnormality exists even when vibrations decrease (for example, when the monitored equipment stops).

[0023] (9)-(11) A diagnostic device according to the present invention comprises a vibration sensor that measures vibrations of an object to be monitored, a vibration judgment reference value calculation means that calculates a vibration judgment reference value based on the measurement output of the vibration sensor, an abnormality determination means that determines that the object to be monitored is abnormal in both cases where the vibration judgment reference value exceeds an upper threshold value and where the vibration judgment reference value exceeds a base threshold value set between the upper threshold value and the lower threshold value for a predetermined period of time, and a determination result output means that outputs the determination result of the abnormality determination means.

[0024] Therefore, since an abnormality is determined not only based on the upper limit threshold value but also when the base threshold value is continuously exceeded for a predetermined period of time, it is possible to monitor abnormalities that gradually progress.

[0025] (12) The diagnostic device according to the present invention is characterized in that the upper threshold, the lower threshold and the base threshold are set by the threshold setting means on the basis of a vibration judgment reference value calculated based on the measurement output of the vibration sensor in the teaching mode.

[0026] Therefore, since the threshold value is set based on the actual measurement value, it is possible to set a more appropriate threshold value.

[0027] (13) The diagnostic device according to the present invention is characterized in that the abnormality determination means determines that an abnormality has occurred when the vibration determination reference value falls below a lower threshold value, instead of or in addition to when the vibration determination reference value exceeds an upper threshold value.

[0028] Therefore, even if the value falls below the lower threshold, it can be determined that an abnormality has occurred.

[0029] (14) The diagnostic device according to the present invention is characterized in that the abnormality determination means determines that an abnormality has occurred when the vibration determination reference value has exceeded the base threshold value for a predetermined period of time, or when the vibration determination reference value has fallen below the base threshold value for a predetermined period of time.

[0030] Therefore, it can be determined that an abnormality has occurred even if the value remains below the base threshold value for a predetermined period of time.

[0031] (15) The diagnostic device according to the present invention is characterized in that the abnormality determination means determines that an abnormality has occurred when the upper limit threshold is temporarily exceeded, or when the upper limit threshold is exceeded continuously for a predetermined period of time.

[0032] Therefore, an appropriate abnormality determination can be made.

[0033] (16) A diagnostic method according to the present invention is a method for diagnosing a monitored object based on its vibration, characterized in that the method acquires the vibration of the monitored object, calculates a vibration judgment reference value based on the acquired vibration, and judges that the monitored object is abnormal in either the case where the vibration judgment reference value exceeds an upper threshold value or the case where the vibration judgment reference value exceeds a base threshold value set between the upper threshold value and the lower threshold value for a predetermined period of time.

[0034] Therefore, since an abnormality is determined not only based on the upper limit threshold value but also when the base threshold value is continuously exceeded for a predetermined period of time, it is possible to monitor abnormalities that gradually progress.

[0035] In the present invention, the "vibration judgment criterion calculation means" corresponds to step ST12 in the embodiment.

[0036] In the embodiment, steps ST14, ST15 and steps ST54, ST55 correspond to the "abnormality determining means."

[0037] In the embodiment, step ST19 corresponds to the "determination result output means."

[0038] In the embodiment, steps ST5 to ST7 correspond to the "threshold setting means."

[0039] The concept of "device" includes not only what is constituted by one computer, but also what is constituted by multiple computers connected via a network, etc. Therefore, when the means of the present invention (or even a part of the means) is distributed among multiple computers, these multiple computers correspond to the device.

[0040] The term "program" is a concept that includes not only programs that can be executed directly by a CPU, but also programs in source format, compressed programs, encrypted programs, and programs that work in conjunction with an operating system to perform their functions. [Brief explanation of the drawings]

[0041] [Figure 1] 1 shows a functional configuration of a diagnostic device according to an embodiment of the present invention. [Figure 2] 1 shows the external appearance of the diagnostic main device 2. [Figure 3] 1 shows the hardware configuration of the diagnostic main device 2. [Figure 4]10 is a flowchart of the diagnostic program 42. [Figure 5] FIG. 10 is a diagram for explaining the setting of a threshold value. [Figure 6] 10 is a flowchart of the diagnostic program 42. [Figure 7] FIG. 10 is a diagram for explaining abnormality determination based on an upper limit threshold value. [Figure 8] FIG. 10 is a diagram for explaining abnormality determination based on a base threshold value. [Figure 9] FIG. 10 is a diagram showing an example in which a plurality of main diagnostic devices are connected to a higher-level device 50. [Figure 10] 10 is a functional configuration of a diagnostic device according to a second embodiment. [Figure 11] 10 is a flowchart of the diagnostic program 42. [Figure 12] FIG. 1 is a diagram illustrating a conventional diagnostic method. DETAILED DESCRIPTION OF THE INVENTION

[0042] 1. First embodiment 1.1 Overall structure Fig. 1 shows the functional configuration of a diagnostic device according to one embodiment of the present invention. An acceleration sensor 4, which is a vibration sensor, is attached to the equipment to be monitored. Therefore, the acceleration sensor 4 can measure and output the vibration of the equipment.

[0043] The vibration judgment reference value calculation means 6 of the diagnosis main device 2 calculates a vibration judgment reference value (for example, a vibration level indicating the magnitude of vibration) based on the measurement output of the acceleration sensor. The abnormality determination means 8 refers to the set upper and lower threshold values ​​and determines whether or not there is an abnormality in the equipment based on the vibration judgment reference value.

[0044] For example, when an abnormality occurs in a device, the amplitude of vibration often increases. Therefore, the abnormality determination means 6 determines that the device is abnormal if the vibration determination reference value exceeds the upper threshold value continuously for a first predetermined time. Since the reference value exceeds the upper threshold value continuously for the first predetermined time, there is no malfunction due to momentary noise, and since statistical values ​​are not used, it is possible to determine abnormalities in the early stages. It is preferable that the upper threshold value be close to the maximum value of the device's vibration during normal operation.

[0045] Furthermore, when the equipment is close to being stopped, the vibration amplitude often decreases. Therefore, the abnormality determination means 8 determines that the equipment is abnormal if the vibration determination reference value remains below the lower threshold for a second predetermined time. Therefore, it is possible to detect not only abnormalities during operation, but also abnormalities when the equipment is not in operation at all. It is preferable that the lower threshold be near the minimum value of the equipment's vibration during normal operation.

[0046] The determination result output means 10 outputs the determination result made by the abnormality determination means 8 .

[0047] As described above, in this embodiment, because upper and lower thresholds are set, it is possible to detect not only abnormalities during equipment operation, but also abnormalities such as when the equipment stops. Furthermore, because an abnormality is determined to have occurred if it continues for a predetermined period of time, there is no malfunction due to momentary noise, and because statistical values ​​are not used, it is possible to determine even the early stages of an abnormality.

[0048] 1.2 Appearance and hardware configuration Figure 2 shows the external appearance of the diagnostic main unit 2. Although not shown, it is provided with a terminal for inputting the measurement output from the acceleration sensor 4 and a terminal for outputting the judgment result. On the top surface, there is a cheating button 12 for executing a teaching mode, which is a mode for setting a threshold value. The diagnostic main unit 2 is placed near the equipment to be monitored, and receives the measurement output from the acceleration sensor 4 attached to the equipment.

[0049] 3 shows the hardware configuration of the diagnostic main unit 2. The CPU 30 is connected to the teaching button 12, memory 32, A / D converter 34, non-volatile memory 36, and communication circuit 38. The A / D converter 34 converts the measurement outputs from the acceleration sensor 4 and temperature sensor 5 into digital data. The communication circuit 38 is used to transmit the judgment result to a higher-level device or the like. Upon receiving the abnormality judgment, the higher-level device or the like performs abnormality response processing, such as stopping the equipment or turning on an abnormality lamp.

[0050] The non-volatile memory 36 stores an operating system 40 such as TRON and a diagnostic program 42. The diagnostic program 42 performs its functions in cooperation with the operating system 40. However, the diagnostic program 42 may function independently without the operating system 40.

[0051] 1.3 Teaching process In this embodiment, a cheating mode is provided in which a threshold value is set based on actually measured vibrations. When the teaching button 12 is pressed, the device enters teaching mode for a predetermined time (for example, 2 minutes).

[0052] 4 shows a flowchart of the diagnostic program in teaching mode. CPU 30 acquires and records data from acceleration sensor 4 and temperature sensor 5 from A / D converter 34 (step ST1). For the acquired acceleration, the RMS value is calculated in predetermined time units (for example, 0.5-second units) (step ST2). Since the sampling rate of A / D converter 34 is about 1 / 51200 seconds (which may also be a predetermined sampling rate), the RMS for 25600 samples is calculated.

[0053] The CPU 30 repeats the above process until the teaching period has elapsed (step ST3). Therefore, when the teaching period has elapsed, the temperature data, acceleration data, and RMS value during the period are recorded.

[0054] Next, CPU 30 acquires the maximum temperature value within the period, and sets the upper temperature threshold value by adding a margin (for example, 10%) to this maximum value (step ST4). Furthermore, CPU 30 calculates the average value of the acceleration RMS value within the period, and sets this average value as the base threshold value (step ST5). Figure 5 shows a schematic diagram of the set base threshold value.

[0055] The CPU 30 also calculates the maximum value of the acceleration RMS value within the period, and sets the upper acceleration threshold value by adding a margin (for example, a 10% increase) to this maximum value (step ST6). Similarly, the CPU 30 calculates the minimum value of the acceleration RMS value within the period, and sets the lower acceleration threshold value by adding a margin (for example, a 10% decrease) to this minimum value (step ST7). These set values ​​are recorded in the nonvolatile memory 36. Figure 5 shows a schematic diagram of the set upper and lower threshold values.

[0056] The threshold value is set in this manner. Since the setting is based on the actual measurement value, an appropriate value that suits the actual situation is set. It is also preferable to perform the teaching process when a part of the monitored device is replaced or when the object handled by the monitored device (for example, parts transported on a belt conveyor) changes.

[0057] 1.4 Diagnostic Processing 6 shows a flowchart of the diagnostic program in the diagnostic mode. CPU 30 acquires and records data from acceleration sensor 4 and temperature sensor 5 from A / D converter 34 (step ST11). For the acquired acceleration, the RMS value is calculated in 0.5-second increments (or between 0.1 and 1 second) (step ST12). Since the sampling rate of A / D converter 34 is approximately 1 / 51200 seconds, the RMS for 25,600 samples is calculated.

[0058] Next, the CPU 30 determines whether the maximum value of the recorded temperatures exceeds the upper temperature threshold (step ST13). If it does, the CPU 30 determines that there is a temperature abnormality (step S17). Because temperature does not change significantly instantaneously due to disturbances or the like, it is appropriate to determine whether the temperature exceeds the threshold. However, it may also be determined whether the temperature falls below the threshold.

[0059] Next, the CPU 30 determines whether the calculated RMS value has exceeded the acceleration upper limit threshold continuously for a first predetermined time (for example, 3 seconds or more) (step ST14). As shown in B in Fig. 7, if the RMS value exceeds the upper limit threshold continuously for 3 seconds or more, it is determined to be abnormal (step ST18). Note that, as shown in A, even if the RMS value exceeds the upper limit threshold, if it continues for less than 3 seconds, it is not determined to be abnormal.

[0060] Similarly, the CPU 30 determines whether the calculated RMS value has been below the acceleration lower limit threshold continuously for a second predetermined time (for example, 3 seconds or more) (step ST15). If the calculated RMS value has been below the acceleration lower limit threshold continuously for 3 seconds or more, it determines that an abnormality has occurred (step ST18).

[0061] Furthermore, the CPU 30 determines whether the calculated RMS value has continuously exceeded the base threshold value for a third predetermined time (preferably longer than the first and second predetermined times, e.g., 10 seconds or more) (step ST16). As shown in C in FIG. 8, if the RMS value has continuously exceeded the base threshold value for 10 seconds or more, it is determined to be abnormal (step ST18). In other words, even if the RMS value does not exceed the upper threshold value, if the RMS value has continuously exceeded the base threshold value for a long period of time, there is a high possibility that an abnormality exists.

[0062] The CPU 30 transmits the above-mentioned determination result to the higher-level device via the communication circuit 38 (step ST19). After completing the above-mentioned process, the CPU 30 again repeatedly executes the process from step ST11 onwards.

[0063] In this way, abnormalities in the monitored equipment to which the acceleration sensor 4 and the temperature sensor 5 are attached can be diagnosed in real time.

[0064] 1.5 Other (variations) (1) In the above embodiment, the diagnostic device calculates and sets the threshold value by itself using the vibration and temperature measured in the teaching mode. However, the threshold value may be calculated by another device, recorded, and set.

[0065] (2) In the above embodiment, the RMS value is used as the vibration determination reference value, but other representative values ​​such as a peak value or a crest factor may also be used.

[0066] (3) In the above embodiment, an abnormality due to vibration is determined using an upper threshold value, a lower threshold value, and a base threshold value. However, the determination may be made using only the upper threshold value and the lower threshold value without using the base threshold value. Also, the determination may be made using only one of the upper threshold value and the lower threshold value. For example, when an abnormality occurs in a press machine and there is a high possibility that vibration due to the press operation will no longer occur, only the lower threshold value may be used.

[0067] (4) In the above embodiment, the average value of the RMS values ​​in the teaching mode is used as the base threshold value. However, a value between the maximum and minimum values ​​other than the average value, such as the median value of the histogram, may also be used.

[0068] (5) In the above embodiment, the upper and lower threshold values ​​are set by providing margins for the maximum and minimum values. However, the maximum and minimum values ​​may be used as the upper and lower threshold values ​​as they are.

[0069] (6) In the above embodiment, an abnormality is determined when the RMS value exceeds the base threshold value for a predetermined period of time. However, instead of or in addition to this, an abnormality may be determined when the RMS value falls below the base threshold value for a predetermined period of time.

[0070] (7) In the above embodiment, the abnormality determination is sent to the host device without distinguishing whether the abnormality is determined based on the upper threshold, the lower threshold, or the base threshold. However, the abnormality determination may be sent to the host device with these distinctions made.

[0071] (8) In the above embodiment, both temperature-based and vibration-based abnormality determinations are performed. However, it is also possible to perform only one of these determinations.

[0072] (9) In the above embodiment, the determination result is transmitted to the host device for output. However, the determination result may be output by turning on an LED or displaying a warning.

[0073] (10) In the above embodiment, the acceleration sensor 4 is used as a vibration sensor, but other vibration sensors such as a speed sensor or a displacement sensor may also be used.

[0074] (11) In the above embodiment, the judgment result is transmitted to the host device only when an abnormality occurs. However, the judgment result may also be transmitted when the device is in a normal state. Furthermore, when transmitting the judgment result, the vibration RMS value and temperature may also be transmitted.

[0075] (12) In the above embodiment, the teaching mode is entered by pressing the teaching button 12. However, the teaching mode may also be entered by an external control signal (for example, a control signal from a higher-level device).

[0076] (13) In the above embodiment, the explanation has been given focusing on one diagnostic main device 2. As shown in FIG. 9, multiple diagnostic main devices 2a to 2n may be connected to a higher-level device 50. The acceleration sensors 4 and temperature sensors 5 of the multiple diagnostic main devices 2a to 2n are attached to different locations of the same device to be diagnosed, or to different devices to be diagnosed. The higher-level device 50 receives the diagnostic results from the multiple diagnostic main devices 2a to 2n and comprehensively evaluates them to accurately determine whether an abnormal state exists.

[0077] For example, if the acceleration sensors 4 and temperature sensors 5 of the diagnostic main units 2a to 2n are installed at different locations on a line conveyor, and abnormalities occur concentrated in multiple diagnostic main units 2d, 2e, and 2f at a specific location, it can be inferred that a device (such as a cooling blower) that operates in common at the locations where these three diagnostic main units 2d, 2e, and 2f are installed has failed.

[0078] 9, the diagnostic main devices 2a to 2n may be configured to transmit not only the diagnostic results but also the vibration RMS values, and the vibration RMS values ​​from each of the diagnostic main devices 2a to 2n may be compared to determine that a diagnostic main device with an abnormal value is abnormal. Alternatively, such a determination may be combined with the determination based on the threshold value described above to determine that an abnormality has occurred.

[0079] (14) In the above embodiment, one acceleration sensor 4 and one temperature sensor 5 are provided for one diagnostic main device. However, a plurality of acceleration sensors 4 and a plurality of temperature sensors 5 may be provided for one diagnostic main device. A plurality of locations can be monitored by a single diagnostic main device.

[0080] (15) The above-described embodiment and modifications can be implemented in combination with other embodiments and modifications thereof.

[0081] 2. Second embodiment 2.1 Overall structure Fig. 10 shows the functional configuration of a diagnostic device according to one embodiment of the present invention. An acceleration sensor 4, which is a vibration sensor, is attached to the equipment to be monitored. Therefore, the acceleration sensor 4 can measure and output the vibration of the equipment.

[0082] The vibration judgment reference value calculation means 6 of the diagnosis main device 2 calculates a vibration judgment reference value (for example, a vibration level indicating the magnitude of vibration) based on the measurement output of the acceleration sensor. The abnormality determination means 8 refers to the set upper limit threshold, lower limit threshold, and base threshold, and determines whether or not there is an abnormality in the equipment based on the vibration judgment reference value.

[0083] For example, when an abnormality occurs in a device, the amplitude of vibration often increases. Therefore, the abnormality determination means 8 determines that the device is abnormal when the vibration determination reference value exceeds the upper threshold. Note that the upper threshold is preferably close to the maximum value of the device's vibration during normal operation.

[0084] Furthermore, when the equipment is close to being stopped, the vibration amplitude often decreases. Therefore, the abnormality determination means 8 determines that the equipment is abnormal when the vibration determination reference value falls below the lower threshold. Therefore, it is possible to detect not only abnormalities during operation, but also abnormalities such as when the equipment is not in operation at all. It is preferable that the lower threshold be close to the minimum value of the equipment's vibration during normal operation.

[0085] Furthermore, if the vibration exceeds a base threshold set between the upper and lower thresholds for a predetermined period of time, the device is also determined to be abnormal. Even if the vibration does not exceed the upper or lower thresholds, if the vibration continues to increase for a predetermined period of time, there is a high possibility that an abnormality has occurred. Therefore, it is possible to detect abnormalities that gradually progress.

[0086] The determination result output means 10 outputs the determination result made by the abnormality determination means 8 .

[0087] As described above, in this embodiment, since an upper threshold, a lower threshold, and a base threshold are set, it is possible to detect an abnormality that progresses gradually.

[0088] 2.2 Appearance and hardware configuration The external appearance and hardware configuration are the same as those in the first embodiment shown in FIGS.

[0089] 2.3 Teaching process The teaching process is the same as that shown in FIG. 4 in the first embodiment.

[0090] 2.4 Diagnostic Processing In the first embodiment, if the upper threshold value is continuously exceeded for a predetermined time, or if the lower threshold value is continuously below for a predetermined time, it is determined to be abnormal. However, in this embodiment, if the upper threshold value is exceeded even temporarily, it is determined to be abnormal.

[0091] A flowchart of the diagnostic program in the diagnostic mode is shown in Fig. 11. Similarly, CPU 30 takes in data from acceleration sensor 4 and temperature sensor 5, and calculates the RMS value of acceleration sensor 4 (steps ST11 and ST12).

[0092] Next, the CPU 30 determines whether the maximum value of the recorded temperatures exceeds the upper temperature threshold (step ST13). If it does, the CPU 30 determines that an abnormality has occurred due to the temperature (step S17).

[0093] Next, the CPU 30 determines whether the calculated RMS value exceeds the upper acceleration threshold (step ST54). In Fig. 7, it is determined that not only the entire period B but also the period A is abnormal (step ST18).

[0094] Similarly, the CPU 30 determines whether the calculated RMS value is below the acceleration lower limit threshold (step ST55), and if it is below the acceleration lower limit threshold, determines that there is an abnormality (step ST18).

[0095] Furthermore, the CPU 30 determines whether the calculated RMS value has exceeded the base threshold value continuously for a predetermined time (for example, 10 seconds or more) (step ST16). If the RMS value has exceeded the base threshold value for 10 seconds or more, as shown in C in Fig. 8, it is determined that an abnormality has occurred (step ST18). In other words, even if the RMS value does not exceed the upper limit threshold value, if the RMS value has exceeded the base threshold value for a long period of time, there is a high possibility that an abnormality has occurred.

[0096] The CPU 30 transmits the above-mentioned determination result to the higher-level device via the communication circuit 38 (step ST19). After completing the above-mentioned process, the CPU 30 again repeatedly executes the process from step ST11 onwards.

[0097] In this way, abnormalities in the monitored equipment to which the acceleration sensor 4 and the temperature sensor 5 are attached can be diagnosed in real time.

[0098] 2.5 Other (variations) (1) In the above embodiment, if the RMS value exceeds (falls below) the upper (lower) limit of acceleration, it is determined to be abnormal. However, it may also be determined to be abnormal if the RMS value exceeds (falls below) the upper (lower) limit for a predetermined period of time.

[0099] (2) The above-described embodiment and modifications can be implemented in combination with other embodiments and modifications thereof.

Claims

1. a vibration sensor for measuring vibrations of a monitored object; a vibration judgment reference value calculation means for calculating a vibration judgment reference value based on the measurement output of the vibration sensor; an abnormality determination means for determining that the monitored object is abnormal not only when the vibration determination reference value exceeds an upper threshold value continuously for a first predetermined time but also when the vibration determination reference value is below a lower threshold value continuously for a second predetermined time; a determination result output means for outputting a determination result of the abnormality determination means; A diagnostic device comprising:

2. a vibration judgment reference value calculation means for calculating a vibration judgment reference value based on a measurement output of a vibration sensor that measures vibrations of the monitored object; an abnormality determination means for determining that the monitored object is abnormal not only when the vibration determination reference value exceeds an upper threshold value continuously for a first predetermined time but also when the vibration determination reference value is below a lower threshold value continuously for a second predetermined time; a determination result output means for outputting a determination result of the abnormality determination means; A diagnostic main unit equipped with the

3. A diagnostic program for realizing a diagnostic master device by a computer, the program comprising: a vibration judgment reference value calculation means for calculating a vibration judgment reference value based on a measurement output of a vibration sensor that measures vibrations of the monitored object; an abnormality determination means for determining that the monitored object is abnormal not only when the vibration determination reference value exceeds an upper threshold value continuously for a first predetermined time but also when the vibration determination reference value is below a lower threshold value continuously for a second predetermined time; a diagnostic program for causing the abnormality determining means to function as a determination result output means for outputting a determination result of the abnormality determining means;

4. In the device or program according to any one of claims 1 to 3, The second predetermined time is equal to the first predetermined time.

5. In the device or program according to any one of claims 1 to 3, The abnormality determination means determines that the monitored object is abnormal if the vibration determination reference value exceeds a base threshold value set between the upper threshold value and the lower threshold value for a third predetermined time period.

6. In the device or program according to any one of claims 1 to 3, The abnormality determination means determines that the monitored object is abnormal if the vibration determination reference value falls below a base threshold value set between the upper threshold value and the lower threshold value for a third predetermined time period.

7. In the device or program according to any one of claims 1 to 3, The apparatus or program is characterized in that the upper limit threshold value and the lower limit threshold value are set by threshold value setting means based on a vibration judgment reference value calculated based on the measurement output of a vibration sensor in a teaching mode.

8. A method for diagnosing a monitored object by its vibration, comprising: Acquire the vibration of the monitored object, Calculating a vibration judgment reference value based on the acquired vibration; A diagnostic method for determining that an object to be monitored is abnormal not only when the vibration judgment reference value exceeds an upper threshold value for a first predetermined time period, but also when the vibration judgment reference value falls below a lower threshold value for a second predetermined time period.

9. a vibration sensor for measuring vibrations of a monitored object; a vibration judgment reference value calculation means for calculating a vibration judgment reference value based on the measurement output of the vibration sensor; an abnormality determination means for determining that the object to be monitored is abnormal in both cases where the vibration determination reference value exceeds an upper threshold value and where the vibration determination reference value continues to exceed a base threshold value set between the upper threshold value and the lower threshold value for a predetermined period of time; a determination result output means for outputting a determination result of the abnormality determination means; A diagnostic device comprising:

10. a vibration judgment reference value calculation means for calculating a vibration judgment reference value based on a measurement output of a vibration sensor that measures vibrations of the monitored object; an abnormality determination means for determining that the object to be monitored is abnormal in both cases where the vibration determination reference value exceeds an upper threshold value and where the vibration determination reference value continues to exceed a base threshold value set between the upper threshold value and the lower threshold value for a predetermined period of time; a determination result output means for outputting a determination result of the abnormality determination means; A diagnostic main unit equipped with the

11. A diagnostic program for realizing a diagnostic master device by a computer, the program comprising: a vibration judgment reference value calculation means for calculating a vibration judgment reference value based on a measurement output of a vibration sensor that measures vibrations of the monitored object; an abnormality determination means for determining that the object to be monitored is abnormal in both cases where the vibration determination reference value exceeds an upper threshold value and where the vibration determination reference value continues to exceed a base threshold value set between the upper threshold value and the lower threshold value for a predetermined period of time; a diagnostic program for causing the abnormality determining means to function as a determination result output means for outputting a determination result of the abnormality determining means;

12. In any one of the devices or programs according to claims 9 to 11, The apparatus or program is characterized in that the upper limit threshold value and the base threshold value are set by threshold value setting means based on a vibration judgment reference value calculated based on the measurement output of a vibration sensor in a teaching mode.

13. In any one of the devices or programs according to claims 9 to 11, The abnormality judgment means judges that an abnormality has occurred when the vibration judgment reference value falls below a lower threshold value, instead of or in addition to when the vibration judgment reference value exceeds an upper threshold value.

14. In any one of the devices or programs according to claims 9 to 11, The abnormality judgment means judges that an abnormality has occurred when the vibration judgment reference value falls below the base threshold value for a predetermined period of time, instead of or in addition to the vibration judgment reference value exceeding the base threshold value for a predetermined period of time.

15. In any one of the devices or programs according to claims 9 to 11, The abnormality determination means determines that an abnormality has occurred when the upper limit threshold is temporarily exceeded, or when the upper limit threshold is exceeded continuously for a predetermined period of time.

16. A method for diagnosing a monitored object by its vibration, comprising: Acquire the vibration of the monitored object, Calculating a vibration judgment reference value based on the acquired vibration; A diagnostic method for determining that an object to be monitored is abnormal in any of the following cases: when the vibration judgment reference value exceeds an upper threshold value, when it is below a lower threshold value, or when it exceeds a base threshold value set between the upper threshold value and the lower threshold value for a predetermined period of time.

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