Diagnostic device

Abstract

[Problem] To provide a diagnostic device that can appropriately perform abnormality diagnosis by using vibrations.　[Solution] A vibration determination reference value computing means 6 of a diagnosis principal device 2 computes a vibration determination reference value (for example, a vibration level indicating the magnitude of vibration) on the basis of the measurement output of an acceleration sensor. An abnormality determination means 8 determines an abnormality if the vibration determination reference value exceeds a set upper-limit threshold for a predetermined period of time. An abnormality is also determined if the vibration determination reference value exceeds a base threshold for a predetermined period of time. Herein, the predetermined period of time for the base threshold is set longer than the predetermined period of time for the upper-limit threshold.

Description

diagnostic equipment

[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.

[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 an appliance detected during a first time period, which serves as a reference, is calculated. Similarly, the average value of vibrations of the appliance detected during a second time period, which is the subject of diagnosis, is calculated. As shown in Figure 13, diagnosis is performed by comparing an average value AV2 during the first time period with an average value AV3 during the second time period.

[0005] Patent Publication No. 2023-169717

[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.

[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 caused by the operation of a monitored object, 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 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, 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 predetermined 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 vibration decreases (for example, when the monitored equipment stops or the rotation speed decreases).

[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 vibrations during operation, characterized in that it acquires the vibrations of the monitored object, calculates a vibration judgment reference value based on the acquired vibrations, 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 predetermined 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) 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 in either case where the vibration judgment reference value exceeds an upper limit threshold value or where the vibration judgment reference value exceeds a base threshold value that is set based on the median value of vibrations due to normal operation 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) The diagnostic method of the present invention is a method for diagnosing a monitored object based on its vibrations, characterized in that it acquires the vibrations of the monitored object, calculates a vibration judgment reference value based on the acquired vibrations, and determines that the monitored object is abnormal in either case where the vibration judgment reference value exceeds an upper limit threshold value or where the vibration judgment reference value exceeds a base threshold value set based on the median value of vibrations due to normal operation 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 standard calculation means" corresponds to step ST12 in the embodiment.

[0036] In the embodiment, steps ST15, ST16 and steps ST55, ST56 correspond to the "abnormality determining means."

[0037] In the embodiment, step ST20 corresponds to the "determination result output means."

[0038] In the embodiment, steps ST6 to ST8 correspond to the "threshold value setting means."

[0039] The concept of "device" includes not only a device consisting of one computer, but also a device consisting of multiple computers connected via a network, etc. Therefore, when the means of the present invention (or a part of the means) is distributed across 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 source-format programs, compressed programs, encrypted programs, programs that work in conjunction with an operating system to perform their functions, and the like.

[0041] 1 is a functional configuration of a diagnostic device according to an embodiment of the present invention. FIG. 2 is an external view of the diagnostic main device 2. FIG. 3 is a hardware configuration of the diagnostic main device 2. FIG. 4 is a flowchart of the diagnostic program 42. FIG. 5 is a diagram showing a process of calculating an RMS value from a vibration acceleration waveform. FIG. 6 is a diagram for explaining threshold value setting. FIG. 7 is a flowchart of the diagnostic program 42. FIG. 8 is a diagram for explaining abnormality determination based on an upper limit threshold value. FIG. 9 is a diagram for explaining abnormality determination based on a base threshold value. FIG. 10 is a diagram showing an example in which a plurality of diagnostic main devices are connected to a higher-level device 50. FIG. 11 is a functional configuration of a diagnostic device according to a second embodiment. FIG. 12 is a flowchart of the diagnostic program 42. FIG. 13 is a diagram showing a conventional diagnostic method.

[0042] 1. First Embodiment 1.1 Overall Configuration Figure 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 diagnostic 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 for a first predetermined time. Since the reference value exceeds the upper threshold value for a 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 near 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 when the vibration determination reference value falls below the lower threshold for a second predetermined time. 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.

[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 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 the 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 teaching button 12, memory 32, A / D converter 34, non-volatile memory 36, and communication circuit 38 are connected to the CPU 30. 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 transmits 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 teaching mode is provided in which a threshold value is set based on actually measured vibration. 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. The CPU 30 acquires and records data from the acceleration sensor 4 and temperature sensor 5 from the A / D converter 34 (step ST1). In this embodiment, the output of the acceleration sensor 4 is recorded at a sampling rate of about 1 / 51200 seconds (which may be a predetermined sampling rate).

[0053] The CPU 30 performs a filtering process on the recorded data (acceleration waveform) from the acceleration sensor 4 to cut out frequency components below 10 Hz and frequency components above 20 kHz (step ST2). This is because vibrations caused by equipment operation are dominated by the frequency band between 10 Hz and 20 kHz. The filtered acceleration waveform is shown in Figure 5A.

[0054] The CPU 30 calculates the RMS value for 1000 msec (i.e., 1 sec) of the acceleration data (acceleration waveform) in Fig. 5A as the vibration judgment reference value (step ST3). Next, the CPU 30 shifts the RMS value back by 10 msec and calculates the RMS value for 1000 msec. By repeating this process, RMS values ​​are generated at 10 msec intervals.

[0055] 5B shows a plot of the RMS values ​​thus generated, which in this embodiment are plotted with a center point of 1000 mS, which is the range for which the RMS values ​​are generated.

[0056] The CPU 30 repeats the above process until the teaching period has elapsed (step ST4). The CPU 30 also records the temperature data at the time the RMS value was recorded. Therefore, when the teaching period has elapsed, the temperature data, acceleration data, and RMS value for that period are recorded.

[0057] Next, the CPU 30 obtains 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 ST5). Furthermore, the 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 ST6). The set base threshold value is schematically shown in FIG. 6. Note that, although the base threshold value is set above using the average value as the center value, it is also possible to set the base threshold value using the median value obtained by histogram analysis as the center value.

[0058] The CPU 30 also calculates the maximum acceleration RMS value within the period, and sets the upper acceleration threshold value by adding a margin (for example, 10% increase) to this maximum value (step ST7). Similarly, the CPU 30 calculates the minimum acceleration RMS value within the period, and sets the lower acceleration threshold value by adding a margin (for example, 10% decrease) to this minimum value (step ST8). These set values ​​are recorded in the non-volatile memory 36. Figure 6 shows a schematic diagram of the set upper and lower threshold values.

[0059] The threshold values ​​are set in this manner. Because the settings are based on actual measurements, appropriate values ​​are set that reflect the actual situation. It is also preferable to perform the teaching process when a part in the monitored device is replaced, or when the objects handled by the monitored device (for example, parts transported on a belt conveyor) change.

[0060] 7 shows a flowchart of the diagnostic program in the diagnostic mode. The CPU 30 acquires and records data from the acceleration sensor 4 and temperature sensor 5 via the A / D converter 34 (step ST11). In this embodiment, the output of the acceleration sensor 4 is recorded at a sampling rate of approximately 1 / 51200 seconds (which may be a predetermined sampling rate).

[0061] The CPU 30 performs a filtering process on the recorded data (acceleration waveform) of the acceleration sensor 4 to cut out frequency components below 10 Hz and frequency components above 20 KHz (step ST12).

[0062] In this embodiment, frequency components below 10 Hz and above 20 kHz are cut, i.e., frequency components between 10 Hz and 20 kHz are left as the inspection target. The inspection target band is preferably a frequency band that includes both normal vibrations of the target machine (in this embodiment, the main vibration under normal conditions is vibration caused by the rotation of the bearing) and abnormal vibrations that occur when an abnormality occurs (for example, when the bearing is damaged) and are superimposed on this normal vibration.

[0063] The reason for cutting frequency components below 10 Hz is that external vibrations such as earthquakes exist in a frequency band lower than the vibrations caused by the operation of the target machine, and these vibrations become noise in relation to the vibrations caused by the operation of the equipment. Therefore, if the vibrations caused by the target machine have a high frequency, cutting may be performed at frequencies higher than 10 Hz. Conversely, if the vibrations caused by the target machine have a low frequency, cutting may be performed at frequencies lower than 10 Hz.

[0064] The reason for cutting frequencies above 20 kHz is that most vibration components that occur during abnormal conditions are thought not to occur above 20 kHz, and that external vibrations caused by ultrasonic waves, radio waves, etc. occur in frequency bands above 20 kHz. Therefore, if vibrations that occur during abnormal conditions occur frequently at high frequencies, cutting may be performed at frequencies higher than 20 kHz. Conversely, if vibrations that occur during abnormal conditions occur frequently at low frequencies, cutting may be performed at frequencies lower than 20 kHz.

[0065] The CPU 30 calculates the RMS value for 1000 msec (i.e., 1 sec) of the filtered acceleration data (acceleration waveform) as a vibration judgment reference value (step ST13). Next, the CPU 30 shifts the data back 10 msec and calculates the RMS value for 1000 msec. By repeating this process, RMS values ​​are generated at 10 msec intervals. The CPU 30 records the temperature along with the RMS value.

[0066] Next, the CPU 30 determines whether the maximum value of the recorded temperatures exceeds the upper temperature threshold (step ST14). If it does, the CPU 30 determines that there is a temperature abnormality (step S18). 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.

[0067] Next, the CPU 30 determines whether the calculated RMS value has exceeded the acceleration upper limit threshold continuously for a first predetermined time (e.g., 3 seconds or more) (step ST15). As shown in Fig. 8, if the RMS value exceeds the upper limit threshold continuously for 3 seconds or more, it is determined that an abnormality has occurred (step ST19). 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 that an abnormality has occurred.

[0068] Similarly, the CPU 30 determines whether the calculated RMS value has been below the acceleration lower limit threshold continuously for a second predetermined time (e.g., 3 seconds or more) (step ST16). If the RMS value has been below the acceleration lower limit threshold continuously for 3 seconds or more, the CPU 30 determines that an abnormality has occurred (step ST19).

[0069] 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 ST17). As shown in C in Fig. 9, if the RMS value has continuously exceeded the base threshold value for 10 seconds or more, it is determined that an abnormality has occurred (step ST19). 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, it is highly likely that an abnormality is gradually progressing.

[0070] The CPU 30 transmits the above-mentioned determination result to the host device via the communication circuit 38 (step ST20). After completing the above-mentioned process, the CPU 30 again repeats the process from step ST11 onwards.

[0071] In this manner, abnormalities in the monitored equipment to which the acceleration sensor 4 and the temperature sensor 5 are attached can be diagnosed in real time.

[0072] 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.

[0073] (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.

[0074] (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.

[0075] (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.

[0076] (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.

[0077] (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.

[0078] (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.

[0079] (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.

[0080] (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.

[0081] (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.

[0082] (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.

[0083] (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).

[0084] (13) In the above embodiment, the explanation focuses on one diagnostic main unit 2. As shown in FIG. 10, multiple diagnostic main units 2a to 2n may be connected to a host unit 50. The acceleration sensors 4 and temperature sensors 5 of the multiple diagnostic main units 2a to 2n are attached to different locations on the same device to be diagnosed, or to different devices to be diagnosed. The host unit 50 receives the diagnostic results from the multiple diagnostic main units 2a to 2n and makes a comprehensive judgment to accurately determine whether an abnormality exists.

[0085] For example, if the acceleration sensors 4 and temperature sensors 5 of the diagnostic main units 2a to 2n are attached to 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 attached may have failed.

[0086] 10, the diagnostic main units 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 units 2a to 2n may be compared to determine that a diagnostic main unit 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.

[0087] Furthermore, if the main diagnostic device 2a is configured to detect vibrations in the vertical direction (first direction) and the main diagnostic device 2b is configured to detect vibrations in the horizontal direction (second direction), it can be estimated which vibration direction component is related to the part that has become abnormal.

[0088] (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.

[0089] (15) In the above embodiment, the acceleration waveform is filtered by software processing. However, a hardware filter may also be used.

[0090] In the above embodiment, the acceleration waveform between 10 Hz (lower limit) and 20 kHz (upper limit) is filtered and extracted, but the output from the acceleration sensor may be used as is without filtering.

[0091] (16) In the above embodiment, the RMS value is calculated for the acceleration waveform in the target range of 1000 mS. However, the RMS value may be calculated in a predetermined target range (for example, 500 mS).

[0092] (17) In the above embodiment, the RMS value is calculated by shifting the target range by 10 mS at a time, while overlapping the target range. However, the shift time may be a predetermined time (for example, 20 mS).

[0093] Alternatively, the RMS value may be calculated without overlapping the target ranges.

[0094] (18) In the above embodiment, an acceleration vibration sensor is attached to the housing to detect and diagnose vibrations of components that generate periodic vibrations during operation, such as rotating bearings. However, vibrations may be detected for components other than rotating bearings that generate periodic vibrations during operation, such as motors. Furthermore, vibrations may be detected for components that do not necessarily generate periodic vibrations during operation but generate random vibrations.

[0095] (19) The above-described embodiment and modifications can be implemented in combination with other embodiments and modifications thereof.

[0096] 2. Second Embodiment 2.1 Overall Configuration Figure 11 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.

[0097] The vibration judgment reference value calculation means 6 of the diagnostic 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 threshold, lower threshold, and base threshold, and determines whether or not there is an abnormality in the equipment based on the vibration judgment reference value.

[0098] 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 an upper threshold. Note that the upper threshold is preferably close to the maximum value of the device's vibration during normal operation.

[0099] 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.

[0100] 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.

[0101] The determination result output means 10 outputs the determination result made by the abnormality determination means 8 .

[0102] 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.

[0103] 2.2 Appearance and Hardware Configuration The appearance and hardware configuration are the same as those in the first embodiment shown in FIGS.

[0104] 2.3 Teaching Process The teaching process is the same as that shown in FIG. 4 in the first embodiment.

[0105] 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 that an abnormality has occurred. However, in this embodiment, if the upper threshold value is exceeded even temporarily, it is determined that an abnormality has occurred.

[0106] 12 shows a flowchart of the diagnostic program in the diagnostic mode. The CPU 30 takes in data from the acceleration sensor 4 and the temperature sensor 5, and for the acceleration sensor 4, it filters the data and calculates the RMS value (steps ST11, ST12, ST13).

[0107] Next, the CPU 30 determines whether the maximum value of the recorded temperatures exceeds the upper temperature threshold (step ST14). If it does, the CPU 30 determines that there is a temperature abnormality (step S18).

[0108] Next, the CPU 30 determines whether the calculated RMS value exceeds the upper acceleration threshold (step ST55). In FIG. 7, it determines that not only the entire period B but also the period A is abnormal (step ST19).

[0109] Similarly, the CPU 30 determines whether the calculated RMS value is below the acceleration lower limit threshold (step ST56), and if so, determines that an abnormality has occurred (step ST19).

[0110] 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 ST17). If the RMS value has exceeded the base threshold value for 10 seconds or more, as shown in C in Fig. 9, it is determined that an abnormality has occurred (step ST19). In other words, even if the RMS value does not exceed the upper 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.

[0111] The CPU 30 transmits the above-mentioned determination result to the host device via the communication circuit 38 (step ST20). After completing the above-mentioned process, the CPU 30 again repeats the process from step ST11 onwards.

[0112] In this manner, abnormalities in the monitored equipment to which the acceleration sensor 4 and the temperature sensor 5 are attached can be diagnosed in real time.

[0113] 2.5 Other (Modifications) (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.

[0114] (2) The above-described embodiment and modifications can be implemented in combination with other embodiments and modifications thereof.

Claims

1. A diagnostic device comprising: a vibration sensor that measures vibrations caused by the operation of a monitored object; a vibration judgment reference value calculation means that calculates a vibration judgment reference value based on the measurement output of said vibration sensor; anomaly judgment means that judges that the monitored object is abnormal not only when said vibration judgment reference value exceeds an upper threshold value for a first predetermined time period continuously, but also when said vibration judgment reference value is below a lower threshold value for a second predetermined time period continuously; and a judgment result output means that outputs the judgment result of said anomaly judgment means.

2. A diagnostic main device comprising: a vibration judgment reference value calculation means for calculating a vibration judgment reference value based on the measurement output of a vibration sensor that measures vibrations caused by the operation of the monitored object; an abnormality judgment means for judging 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; and a judgment result output means for outputting the judgment result of the abnormality judgment means.

3. A diagnostic program for realizing a diagnostic main device by a computer, which causes the computer to function as: vibration judgment reference value calculation means for calculating a vibration judgment reference value based on the measurement output of a vibration sensor that measures vibrations caused by the operation of the monitored object; abnormality judgment means for judging 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; and judgment result output means for outputting the judgment result of the abnormality judgment means.

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

5. A device or program according to any one of claims 1 to 3, wherein the abnormality determination means determines that the monitored object is abnormal even 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. A device or program according to any one of claims 1 to 3, wherein the abnormality determination means determines that the monitored object is abnormal even 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. A device or program according to any one of claims 1 to 3, wherein the upper and lower thresholds are set by threshold setting means based on a vibration judgment reference value calculated based on the measurement output of a vibration sensor in teaching mode.

8. A method for diagnosing a monitored object based on vibrations caused by its operation, comprising: acquiring vibrations of the monitored object; calculating a vibration judgment reference value based on the acquired vibrations; and determining 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.

9. A diagnostic device comprising: 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 said vibration sensor; anomaly judgment means that judges that the object to be monitored is abnormal in either case where said vibration judgment reference value exceeds an upper threshold value or where said vibration judgment reference value exceeds a base threshold value that is set based on the median value of vibrations due to normal operation for a predetermined period of time; and a judgment result output means that outputs the judgment result of said anomaly judgment means.

10. A diagnostic main device comprising: a vibration judgment reference value calculation means for calculating a vibration judgment reference value based on the measurement output of a vibration sensor that measures vibrations of the monitored object; an abnormality judgment means for judging that the monitored object is abnormal in either case where the vibration judgment reference value exceeds an upper threshold value or where the vibration judgment reference value exceeds a base threshold value set based on the median value of vibrations due to normal operation for a predetermined period of time; and a judgment result output means for outputting the judgment result of the abnormality judgment means.

11. A diagnostic program for realizing a diagnostic main device by a computer, which causes the computer to function as: vibration judgment reference value calculation means for calculating a vibration judgment reference value based on the measurement output of a vibration sensor that measures the vibration of the monitored object; abnormality judgment means for determining that the monitored object 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 based on the median value of vibration due to normal operation for a predetermined period of time; and judgment result output means for outputting the judgment result of the abnormality judgment means.

12. A device or program according to any one of claims 9 to 11, wherein the upper limit threshold and base threshold are set by threshold setting means based on a vibration judgment reference value calculated based on the measurement output of a vibration sensor in teaching mode.

13. A device or program according to any one of claims 9 to 11, wherein 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.

14. A device or program according to any one of claims 9 to 11, wherein the abnormality determination means determines that an abnormality has occurred when the vibration determination reference value falls below the base threshold value for a predetermined period of time, instead of or in addition to the vibration determination reference value exceeding the base threshold value for a predetermined period of time.

15. A device or program according to any one of claims 9 to 11, wherein 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 based on its vibrations, comprising: acquiring the vibrations of the monitored object; calculating a vibration judgment reference value based on the acquired vibrations; and determining that the monitored object is abnormal in either case where the vibration judgment reference value exceeds an upper threshold value or where the vibration judgment reference value exceeds a base threshold value set based on the median value of vibrations due to normal operation for a predetermined period of time.

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