Anomaly detection device and anomaly detection method

Abstract

To enable an abnormality in an ultrasonic flowmeter to be detected earlier than before.SOLUTION: The present invention comprises: a received signal acquisition unit 401 and a received signal acquisition unit 402 for acquiring a received signal; a zero-cross point measurement unit 403 and a zero-cross point measurement unit 404 for measuring a time till a zero-cross point multiple times for each of a plurality of unit measurement steps; a time difference calculation unit 405 for calculating a time difference between measurement results from the zero-cross point measurement unit 403 and measurement results from the zero-cross point measurement unit 404; an average value calculation unit 406 for calculating the average value of time differences at a first-half zero-cross point; an average value calculation unit 407 for calculating the average value of time differences at a latter-half zero-cross point; a difference calculation unit 408 for calculating the absolute value of the difference between calculation results from the average value calculation unit 406 and calculation results from the average value calculation unit 407; and an abnormality detection unit 409 for comparing the absolute value of the difference calculated by the difference calculation unit 408 with a threshold so as to detect an abnormality in an ultrasonic flowmeter.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an abnormality detection device and an abnormality detection method for detecting an abnormality in an ultrasonic flowmeter. [Background technology]

[0002] 2. Description of the Related Art Conventionally, ultrasonic flowmeters are known that measure the flow rate of a fluid to be measured based on the difference in propagation time between ultrasonic waves transmitted and received by a pair of ultrasonic sensors. In such ultrasonic flowmeters, if the ultrasonic sensor that transmits and receives ultrasonic waves fails, there will be no significant change in the strength of the received signal or the TOF time, but an error may occur in the propagation time difference due to a change in the sensor characteristics. If the ultrasonic flowmeter continues to measure without detecting such an abnormality, an error will occur in the flow measurement, and there is a possibility that the measurement accuracy cannot be guaranteed.

[0003] In response to this, for example, Patent Document 1 discloses a method of issuing a warning when the strength of a received signal is outside a predetermined range or when the propagation time is too long. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4673950 Summary of the Invention [Problem to be solved by the invention]

[0005] However, while the conventional method disclosed in Patent Document 1 is effective as an indicator for detecting large changes in the received signal, it is insufficient as an indicator for early detection of abnormalities in the ultrasonic sensor.

[0006] The present invention has been made to solve the above-mentioned problems, and has an object to provide an abnormality detection device that can detect an abnormality in an ultrasonic sensor earlier than conventional devices. [Means for solving the problem]

[0007] The anomaly detection device according to the present invention includes a first received signal acquisition unit that acquires a received signal received by one of the ultrasonic sensors of the ultrasonic flowmeter, a second received signal acquisition unit that acquires a received signal received by the other ultrasonic sensor of the ultrasonic flowmeter, a first zero-cross point measurement unit that measures the time from the start of transmission to a zero-cross point a plurality of times for each of a plurality of unit measurement steps based on the acquisition results by the first received signal acquisition unit, a second zero-cross point measurement unit that measures the time from the start of transmission to a zero-cross point a plurality of times for each of a plurality of unit measurement steps based on the acquisition results by the second received signal acquisition unit, and the first zero-cross point measurement unit. the first average value calculation unit calculating an average value of the time differences at the first zero crossing points based on the calculation result by the time difference calculation unit; a second average value calculation unit calculating an average value of the time differences at the second zero crossing points based on the calculation result by the time difference calculation unit; a difference calculation unit calculating an absolute value of the difference between the calculation result by the first average value calculation unit and the calculation result by the second average value calculation unit; and an abnormality detection unit detecting an abnormality in the ultrasonic flowmeter by comparing the absolute value of the difference calculated by the difference calculation unit with a threshold value. Effect of the Invention

[0008] According to the present invention, since it is configured as described above, it becomes possible to detect an abnormality in the ultrasonic sensor earlier than in the past. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating a configuration example of an ultrasonic flowmeter according to a first embodiment. [Diagram 2] FIG. 2 is a diagram illustrating an example of the configuration of a calculation unit according to the first embodiment. [Diagram 3] FIG. 2 is a diagram for explaining zero crossing points. [Figure 4] 5 is a flowchart showing an example of an abnormality detection operation by a calculation unit in the first embodiment. [Diagram 5] FIG. 13 is a diagram for explaining the drift of the zero point in the time difference between the zero crossing points. [Figure 6] FIG. 4 is a diagram showing an example of various parameters used in a calculation unit in the first embodiment. [Figure 7] FIG. 11 is a diagram illustrating an example of the configuration of a calculation unit in the second embodiment. [Figure 8] 8A and 8B are diagrams showing an example of various parameters used in the calculation unit in the second embodiment, with FIG. 8A showing various parameters related to the forward direction and FIG. 8B showing various parameters related to the reverse direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Embodiment 1 FIG. 1 is a diagram showing a configuration example of an ultrasonic flowmeter according to a first embodiment. An ultrasonic flowmeter measures a fluid by using ultrasonic waves. This ultrasonic flowmeter includes a measuring tube 1, an ultrasonic sensor 2, an ultrasonic sensor 3, and a calculation unit 4, as shown in FIG.

[0011] The measuring tube 1 is a cylindrical member through which a fluid to be measured flows.

[0012] The ultrasonic sensor 2 is an ultrasonic transducer that is attached to the upstream side of the side wall of the measurement pipe 1 and transmits and receives ultrasonic waves between it and the ultrasonic sensor 3 inside the measurement pipe 1. That is, the ultrasonic sensor 2 transmits ultrasonic waves to the downstream side (ultrasonic sensor 3) inside the measurement pipe 1, and receives ultrasonic waves from the downstream side (ultrasonic sensor 3) as a reception signal.

[0013] The ultrasonic sensor 3 is an ultrasonic transducer that is attached to the downstream side of the side wall of the measurement pipe 1 and transmits and receives ultrasonic waves between it and the ultrasonic sensor 2 within the measurement pipe 1. That is, the ultrasonic sensor 3 transmits ultrasonic waves to the upstream side (ultrasonic sensor 2) within the measurement pipe 1, and receives ultrasonic waves from the upstream side (ultrasonic sensor 2) as a reception signal.

[0014] The positional relationship between the ultrasonic sensors 2 and 3 is designed according to the propagation paths of the ultrasonic waves transmitted and received by the ultrasonic sensors 2 and 3.

[0015] The calculation unit 4 calculates the flow rate of the fluid in the measuring pipe 1 based on the results of transmission and reception by the ultrasonic sensor 2 and the results of transmission and reception by the ultrasonic sensor 3. The calculation unit 4 also has a function of detecting an abnormality in the ultrasonic flowmeter based on the transmission and reception results by the ultrasonic sensor 2 and the transmission and reception results by the ultrasonic sensor 3 (function of an abnormality detection device).

[0016] As shown in FIG. 2, this calculation unit 4 includes a received signal acquisition unit (first received signal acquisition unit) 401, a received signal acquisition unit (second received signal acquisition unit) 402, a zero cross point measurement unit (first zero cross point measurement unit) 403, a zero cross point measurement unit (second zero cross point measurement unit) 404, a time difference calculation unit 405, an average value calculation unit (first average value calculation unit) 406, an average value calculation unit (second average value calculation unit) 407, a difference calculation unit 408, an abnormality detection unit 409, and a flow rate calculation unit 410.

[0017] Of the components of the calculation unit 4 shown in FIG. 2, the received signal acquisition unit 401, the received signal acquisition unit 402, the zero-cross point measurement unit 403, the zero-cross point measurement unit 404, the time difference calculation unit 405, the average value calculation unit 406, the average value calculation unit 407, the difference calculation unit 408 and the anomaly detection unit 409 constitute an anomaly detection device.

[0018] The calculation unit 4 is realized by a processing circuit such as an integrated circuit (IC) or a system large scale integration (LSI), or a central processing unit (CPU) that executes a program stored in a memory or the like.

[0019] The received signal acquisition unit 401 acquires the received signal received by the ultrasonic sensor 2 .

[0020] The received signal acquisition unit 402 acquires the received signal received by the ultrasonic sensor 3 .

[0021] The zero-crossing point measuring unit 403 measures the time from the start of transmission to the zero-crossing point multiple times based on the acquisition result by the received signal acquiring unit 401. The zero-crossing point measuring unit 403 performs the above process for each of the multiple received signals (each unit measurement step). As shown in FIG. 3, for example, a zero-cross point is a point where the strength of a received signal becomes zero after the strength of the received signal exceeds a threshold (threshold voltage) after reception starts. Usually, the zero-cross point is measured at a point between the reception start point of the received signal and the point where the received signal has a maximum amplitude. In FIG. 3, the upper part shows the transmission waveform of the ultrasonic wave, and the lower part shows the reception waveform of the ultrasonic wave (waveform of the received signal). In FIG. 3, reference numeral 31 indicates the reception start point, reference numeral 32 indicates the threshold, reference numeral 33 indicates the zero-cross point, and reference numeral 34 indicates the point where the received signal has a maximum amplitude. The number of zero-cross points at which the zero-cross point measuring unit 403 measures time in one unit measurement step is set in advance. The number of unit measurement steps is set in advance.

[0022] The zero-crossing point measuring unit 404 measures the time from the start of transmission to the zero-crossing point multiple times based on the acquisition result by the received signal acquiring unit 402. The zero-crossing point measuring unit 404 performs the above process for each of the multiple received signals (each unit measurement step). The number of zero crossing points at which the zero crossing point measuring section 404 measures time in one unit measurement step is set in advance, and the number of unit measurement steps is also set in advance.

[0023] The operations of the received signal acquisition units 401 and 402 and the zero-crossing point measurement units 403 and 404 can be realized by one circuit system. In other words, the above operations can be realized by switching the connection between the above circuits and the ultrasonic sensors 2 and 3 depending on whether transmission and reception is in the forward direction or the reverse direction.

[0024] Time difference calculation unit 405 calculates the time difference between the measurement result by zero cross point measurement unit 403 and the measurement result by zero cross point measurement unit 404. At this time, first, time difference calculation unit 405 calculates an average value by averaging the measurement results in each unit measurement step by zero cross point measurement unit 403 for each zero cross point. Similarly, time difference calculation unit 405 calculates an average value by averaging the measurement results in each unit measurement step by zero cross point measurement unit 404 for each zero cross point. Then, time difference calculation unit 405 calculates the difference between the above two average values ​​for each zero cross point, thereby calculating the time difference at each zero cross point.

[0025] Based on the calculation result by time difference calculation section 405, average value calculation section 406 calculates the average value of the time differences at the first half zero crossing points. In addition, the first half zero crossing point refers to one or more zero crossing points that are close to the reception start point when multiple zero crossing points that occur from the reception start point of the received signal to the point where the received signal has the maximum amplitude are arranged in chronological order.

[0026] Based on the calculation result by time difference calculation section 405, average value calculation section 407 calculates the average value of the time differences at the latter half zero crossing points. In addition, the latter zero crossing point refers to one or more zero crossing points that are farther from the reception start point when multiple zero crossing points that occur from the reception start point of the received signal to the point where the received signal has the maximum amplitude are arranged in chronological order, and is a zero crossing point that occurs after the first zero crossing point.

[0027] The difference calculation unit 408 calculates the absolute value of the difference between the average value calculated by the average value calculation unit 406 and the average value calculated by the average value calculation unit 407 .

[0028] The abnormality detection unit 409 detects an abnormality in the ultrasonic flowmeter by comparing the absolute value of the difference calculated by the difference calculation unit 408 with a threshold value. At this time, the abnormality detection unit 409 determines that no abnormality has occurred in the ultrasonic flowmeter when the absolute value of the difference is equal to or less than the threshold value, and determines that an abnormality has occurred in the ultrasonic flowmeter when the absolute value of the difference is greater than the threshold value. The threshold value is set in advance.

[0029] Flow rate calculation unit 410 calculates the flow rate of the fluid in measuring pipe 1 based on the calculation result by time difference calculation unit 405. As the operating principle of flow rate calculation unit 410, the conventional flow rate calculation principle can be adopted, and the explanation thereof will be omitted.

[0030] In the above description, the ultrasonic flowmeter is provided with the function of the anomaly detection device, but the present invention is not limited to this, and the anomaly detection device may be provided as a device separate from the ultrasonic flowmeter.

[0031] Next, an example of an anomaly detection operation by the calculation unit 4 (anomaly detection device) in the first embodiment shown in FIG. 2 will be described with reference to FIG. Here, the pair of ultrasonic sensors 2, 3 have a phenomenon in which the zero point of the time difference (propagation time difference) used in flow measurement drifts with temperature due to differences in sensor characteristics. If the fluctuation width of this drift is within a predetermined range, the measurement accuracy of the ultrasonic flowmeter is satisfied. Meanwhile, as shown in FIG. 5, when the time difference used in the above flow measurement is broken down into zero crossing points, it can be seen that the later the zero crossing point on the time axis, the greater the influence of temperature change. Therefore, if an ultrasonic sensor fails, the latter zero crossing point will fluctuate more than the first zero crossing point.

[0032] Therefore, the anomaly detection device according to the first embodiment monitors the time difference at the latter half zero crossing point and the time difference at the first half zero crossing point, and detects an anomaly when the difference becomes larger than the expected value under normal conditions. Note that, in flow measurement using an ultrasonic flowmeter, the time difference at each zero crossing point is used, so that an anomaly can be detected before the measurement accuracy cannot be guaranteed.

[0033] In the example of an abnormality detection operation by the calculation unit 4 in the first embodiment shown in FIG. 2, first, as shown in FIG. 4, the received signal acquisition unit 401 and the received signal acquisition unit 402 acquire a received signal (step ST401). That is, the received signal acquisition unit 401 acquires the received signal received by the ultrasonic sensor 2 . Similarly, the received signal acquisition unit 402 acquires the received signal received by the ultrasonic sensor 3 .

[0034] Next, zero-crossing point measuring section 403 and zero-crossing point measuring section 404 measure the time from the start of transmission to the zero-crossing point multiple times for each unit measurement step (step ST402). That is, the zero-crossing point measuring unit 403 measures the time from the start of transmission to the zero-crossing point multiple times for each unit measurement step, based on the results acquired by the received signal acquiring unit 401. Similarly, the zero-crossing point measuring unit 404 measures the time from the start of transmission to the zero-crossing point multiple times for each unit measurement step, based on the results acquired by the received signal acquiring unit 402 .

[0035] 3 shows a case where the zero-cross point measuring section 403 and the zero-cross point measuring section 404 measure the times of six zero-cross points in one unit measurement process. The number of unit measurement processes is, for example, 31.

[0036] The time of the m-th zero cross point in the k-th unit measurement step measured by the zero cross point measuring section 403 is represented as ZCm(k). Moreover, the time of the m-th zero cross point in the k-th unit measurement step measured by the zero cross point measuring section 404 is represented as inverse ZCm(k).

[0037] Next, time difference calculation unit 405 calculates the time difference (ZCmΔt) between the measurement result by zero-cross point measurement unit 403 and the measurement result by zero-cross point measurement unit 404 as shown in the following equation (1) (step ST403). At this time, first, time difference calculation unit 405 calculates an average value by averaging the measurement results in each unit measurement step by zero-cross point measurement unit 403 for each zero-cross point. Similarly, time difference calculation unit 405 calculates an average value by averaging the measurement results in each unit measurement step by zero-cross point measurement unit 404 for each zero-cross point. Then, time difference calculation unit 405 calculates the difference between the above two average values ​​for each zero-cross point, thereby calculating the time difference at each zero-cross point. ZCmΔt=(ΣReverse ZCm(k) / k)-(ΣOrder ZCm(k) / k) (1)

[0038] The flow rate calculation unit 410 can calculate the flow rate of the fluid in the measuring pipe 1 based on the calculation result by the time difference calculation unit 405. That is, the flow rate calculation unit 410 can calculate the flow rate of the fluid based on the time difference (Δt) calculated according to the following formula (2). Δt=ΣZCmΔt / m (2)

[0039] Next, average value calculation unit 406 calculates the average value of the time differences at the first zero crossing points based on the calculation result by time difference calculation unit 405 (step ST404). At this time, for example, average value calculation unit 406 calculates the average value (Δt1_2) of the time differences at the first and second zero crossing points as shown in the following formula (3). Note that, in order to reduce the variation and improve the accuracy of the abnormality determination, average value calculation unit 406 may calculate the final average value (Δt1_2_N) by performing N averaging, that is, by repeating the calculation of the above average value N times (multiple times) and averaging. N is a number sufficient to reduce the influence of random errors. Δt1_2=(ZC1Δt+ZC2Δt) / 2 (3)

[0040] Next, average value calculation unit 407 calculates the average value of the time differences at the latter zero crossing points based on the calculation result by time difference calculation unit 405 (step ST405). At this time, for example, average value calculation unit 407 calculates the average value (Δt5_6) of the time differences at the fifth and sixth zero crossing points as shown in the following formula (4). Note that, in order to reduce the variation and improve the accuracy of the abnormality determination, average value calculation unit 407 may calculate the final average (Δt5_6_N) by performing N averaging, that is, by repeating the calculation of the above average value N times (multiple times) and averaging. N is a number sufficient to reduce the influence of random errors. Δt5_6=(ZC5Δt+ZC6Δt) / 2 (4)

[0041] Next, difference calculation unit 408 calculates the absolute value of the difference between the average value calculated by average value calculation unit 406 and the average value calculated by average value calculation unit 407 (step ST406). At this time, in the above example, difference calculation unit 408 calculates the absolute value of the difference (abnormality determination value) by subtracting the average value of the time differences at the first and second zero crossing points from the average value of the time differences at the fifth and sixth zero crossing points, as shown in the following formula (5). This abnormality determination value is an index value for detecting an abnormality in the ultrasonic flowmeter. Abnormality judgment value = |Δt5_6_N-Δt1_2_N| (5)

[0042] Next, the abnormality detection unit 409 detects an abnormality in the ultrasonic flowmeter by comparing the absolute value of the difference calculated by the difference calculation unit 408 with a threshold value (step ST407). Here, the abnormality detection unit 409 determines that no abnormality has occurred in the ultrasonic flowmeter when the absolute value of the difference is equal to or smaller than the threshold value, and determines that an abnormality has occurred in the ultrasonic flowmeter when the absolute value of the difference is larger than the threshold value. The threshold value used by the anomaly detection unit 409 may be changed as appropriate depending on the flow rate, pressure, temperature, or the like of the fluid to be measured.

[0043] FIG. 6 shows an example of the values ​​of various parameters used in the calculation unit 4 in the first embodiment.

[0044] In the above, as an example, the calculation unit 4 detects an abnormality using Δt5_6 and Δt1_2. However, the present invention is not limited to this, and the calculation unit 4 may detect an abnormality using the time difference at other first-half zero crossing points and the time difference at the second-half zero crossing points. In other words, the number of zero crossing points used by the calculation unit 4, the number of zero crossing points included in the first-half zero crossing points, and the number of zero crossing points included in the second-half zero crossing points are not limited to the above example. In addition, the calculation unit 4 can reduce errors in the zero crossing points caused by the shift of the reference potential (0 point) and the change in the signal strength (slope) by taking the average of the rise-fall pairs (an even number of zero crossing points).

[0045] As described above, according to the first embodiment, the anomaly detection device includes a received signal acquisition unit 401 that acquires a received signal received by the ultrasonic sensor 2, a received signal acquisition unit 402 that acquires a received signal received by the ultrasonic sensor 3, a zero-cross point measurement unit 403 that measures the time from the start of transmission to the zero-cross point a plurality of times for each of a plurality of unit measurement steps based on the acquisition results by the received signal acquisition unit 401, a zero-cross point measurement unit 404 that measures the time from the start of transmission to the zero-cross point a plurality of times for each of a plurality of unit measurement steps based on the acquisition results by the received signal acquisition unit 402, and and the measurement result by the zero cross point measurement unit 404, an average value calculation unit 406 that calculates an average value of the time differences at the first half zero cross points based on the calculation result by the time difference calculation unit 405, an average value calculation unit 407 that calculates an average value of the time differences at the second half zero cross points based on the calculation result by the time difference calculation unit 405, a difference calculation unit 408 that calculates an absolute value of the difference between the calculation result by the average value calculation unit 406 and the calculation result by the average value calculation unit 407, and an abnormality detection unit 409 that detects an abnormality of the ultrasonic flowmeter by comparing the absolute value of the difference calculated by the difference calculation unit 408 with a threshold value. As a result, the abnormality detection device according to the first embodiment can detect an abnormality of the ultrasonic flowmeter earlier than the conventional one. Moreover, the abnormality detection device according to the first embodiment can detect an abnormality of the ultrasonic flowmeter in real time while the ultrasonic flowmeter is performing measurement.

[0046] Embodiment 2 In the anomaly detection device according to the first embodiment, it is possible to detect an anomaly in the ultrasonic flowmeter by using the time difference at the zero crossing points, but it is not possible to detect whether an anomaly has occurred in the ultrasonic sensor 2 or the ultrasonic sensor 3. Therefore, in the second embodiment, a configuration example that makes it possible to detect whether an anomaly has occurred in the ultrasonic sensor 2 or the ultrasonic sensor 3 will be described.

[0047] Fig. 7 is a diagram showing a configuration example of the calculation unit 4 in the second embodiment. In the calculation unit 4 in the second embodiment shown in Fig. 7, the average value calculation unit 406, the average value calculation unit 407, the difference calculation unit 408, and the anomaly detection unit 409 in the calculation unit 4 in the first embodiment shown in Fig. 2 are changed to an average value calculation unit (first average value calculation unit) 406b, an average value calculation unit (second average value calculation unit) 407b, a difference calculation unit 408b, and an anomaly detection unit 409b. The other configuration example of the calculation unit 4 in the second embodiment shown in Fig. 7 is the same as the configuration example of the calculation unit 4 in the first embodiment shown in Fig. 2, and the same reference numerals are used and only different parts will be described.

[0048] The average value calculation unit 406b calculates an average value (first average value) of the time of the first half zero cross point based on the measurement result by the zero cross point measurement unit 403. In this case, the average value calculation unit 406b first calculates an average value by averaging the measurement results in each unit measurement step by the zero cross point measurement unit 403 for each first half zero cross point. Then, the average value calculation unit 406b calculates the first average value by averaging the above average values. Furthermore, average value calculation section 406b calculates an average value (second average value) of the time of the first half zero cross point based on the measurement result by zero cross point measurement section 404. In this case, average value calculation section 406b first calculates an average value by averaging the measurement results in each unit measurement step by zero cross point measurement section 404 for each first half zero cross point. Then, average value calculation section 406b calculates the second average value by averaging each of the average values.

[0049] The average value calculation unit 407b calculates an average value (first average value) of the time of the latter zero crossing points based on the measurement results by the zero crossing point measurement unit 403. In this case, the average value calculation unit 407b first calculates an average value for each latter zero crossing point by averaging the measurement results in each unit measurement step by the zero crossing point measurement unit 403. Then, the average value calculation unit 407b calculates the first average value by averaging the above average values. Furthermore, average value calculation unit 407b calculates an average value (second average value) of the time of the latter zero crossing points based on the measurement results by zero crossing point measurement unit 404. In this case, first, average value calculation unit 407b calculates an average value for each latter zero crossing point by averaging the measurement results in each unit measurement step by zero crossing point measurement unit 404. Then, average value calculation unit 407b calculates the second average value by averaging the above average values.

[0050] Difference calculation unit 408b calculates the absolute value of the difference between the calculation result by average calculation unit 406b and the calculation result by average calculation unit 407b. At this time, difference calculation unit 408b calculates the absolute value of the difference between the first average value calculated by average calculation unit 406b and the first average value calculated by average calculation unit 407b as a first difference value. In addition, difference calculation unit 408b calculates the absolute value of the difference between the second average value calculated by average calculation unit 406b and the second average value calculated by average calculation unit 407b as a second difference value.

[0051] The abnormality detection unit 409b detects an abnormality in the ultrasonic flowmeter by comparing the first difference value and the second difference value calculated by the difference calculation unit 408b with a threshold value. At this time, the abnormality detection unit 409b determines that no abnormality has occurred in the ultrasonic flowmeter when the first difference value is equal to or less than the threshold value, and determines that an abnormality has occurred in the ultrasonic flowmeter (an abnormality has occurred in the forward direction) when the first difference value is greater than the threshold value. Furthermore, the abnormality detection unit 409b determines that no abnormality has occurred in the ultrasonic flowmeter when the second difference value is equal to or less than the threshold value, and determines that an abnormality has occurred in the ultrasonic flowmeter (an abnormality has occurred in the reverse direction) when the second difference value is greater than the threshold value. The threshold value is set in advance.

[0052] Here, for example, the average value calculation unit 406b calculates the average value (forward ZC1_2) of the times of the first and second zero crossing points as the first average value based on the measurement results by the zero crossing point measurement unit 403, as shown in the following equation (6). Similarly, average value calculation unit 406b calculates the average value (inverse ZC1_2) of the times of the first and second zero crossing points as a second average value based on the measurement results by zero crossing point measurement unit 404, as shown in the following equation (7). In addition, in order to reduce variation and improve the accuracy of abnormality judgment, the average value calculation unit 406b may calculate the final average values ​​(forward ZC1_2_N, reverse ZC1_2_N) by repeating the calculation of the first average value and the second average value multiple times and averaging them. Order ZC1_2={(Σorder ZC1(k) / k)+(Σorder ZC2(k) / k)} / 2 (6) Reverse ZC1_2={(ΣReverse ZC1(k) / k)+(ΣReverse ZC2(k) / k)} / 2 (7)

[0053] Next, for example, the average value calculation unit 407b calculates the average value (forward ZC5_6) of the times of the fifth and sixth zero crossing points as the first average value based on the measurement results by the zero crossing point measurement unit 403, as shown in the following equation (8). Similarly, the average value calculation unit 407b calculates the average value (inverse ZC5_6) of the times of the fifth and sixth zero crossing points as a second average value based on the measurement results by the zero crossing point measurement unit 404, as shown in the following equation (9). In addition, in order to reduce variation and improve the accuracy of abnormality judgment, the average value calculation unit 407b may calculate the final average values ​​(forward ZC5_6_N, reverse ZC5_6_N) by repeating the calculation of the first average value and the second average value multiple times and averaging them. Order ZC5_6={(Σ order ZC5(k) / k)+(Σ order ZC6(k) / k)} / 2 (8) Reverse ZC5_6={(ΣReverse ZC5(k) / k)+(ΣReverse ZC6(k) / k)} / 2 (9)

[0054] Next, for example, the difference calculation unit 408b calculates the absolute value of the difference between the first average value calculated by the average value calculation unit 406b and the first average value calculated by the average value calculation unit 407b as a first difference value (abnormality determination value (order)) as shown in the following equation (10). Similarly, the difference calculation unit 408b calculates the absolute value of the difference between the second average value calculated by the average value calculation unit 406b and the second average value calculated by the average value calculation unit 407b as a second difference value (abnormality determination value (inverse)) as shown in the following equation (11). Abnormality judgment value (order) = |Order ZC5_6_N - Order ZC1_2_N| (10) Abnormality judgment value (inverse) = |inverse ZC5_6_N - inverse ZC1_2_N| (11)

[0055] Next, the abnormality detection unit 409b compares the first difference value and the second difference value calculated by the difference calculation unit 408b with a threshold value, respectively, to detect an abnormality in the ultrasonic flowmeter.

[0056] Fig. 8 shows an example of various parameter values ​​used by the calculation unit 4 in embodiment 1. Fig. 8A shows an example of various parameter values ​​related to the forward direction, and Fig. 8B shows an example of various parameter values ​​related to the reverse direction.

[0057] In this way, the anomaly detection device according to embodiment 1 detects anomalies using the time difference at zero crossing points, whereas the anomaly detection device according to embodiment 2 detects anomalies using the time of zero crossing points. As a result, in addition to the effect according to embodiment 1, the anomaly detection device according to embodiment 2 can distinguish between the forward direction and the reverse direction for the ultrasonic sensors 2, 3 and therefore enables the operator to identify the ultrasonic sensor 2, 3 in which an abnormality is occurring.

[0058] As described above, according to the second embodiment, the anomaly detection device includes a received signal acquisition unit 401 that acquires a received signal received by the ultrasonic sensor 2, a received signal acquisition unit 402 that acquires a received signal received by the ultrasonic sensor 3, a zero-cross point measurement unit 403 that measures the time from the start of transmission to the zero-cross point a plurality of times for each of a plurality of unit measurement steps based on the acquisition results by the received signal acquisition unit 401, a zero-cross point measurement unit 404 that measures the time from the start of transmission to the zero-cross point a plurality of times for each of a plurality of unit measurement steps based on the acquisition results by the received signal acquisition unit 402, and The anomaly detection device according to the second embodiment includes an average value calculation unit 406b that calculates an average value of the time of the first half zero cross point based on the measurement result by the zero cross point measurement unit 403 and the measurement result by the zero cross point measurement unit 404, an average value calculation unit 407b that calculates an average value of the time of the second half zero cross point based on the measurement result by the zero cross point measurement unit 403 and the measurement result by the zero cross point measurement unit 404, a difference calculation unit 408b that calculates the absolute value of the difference between the calculation result by the average value calculation unit 406 and the calculation result by the average value calculation unit 407, and an anomaly detection unit 409b that detects an anomaly of the ultrasonic flowmeter by comparing the absolute value of the difference calculated by the difference calculation unit 408b with a threshold value. As a result, the anomaly detection device according to the second embodiment can detect an anomaly of the ultrasonic flowmeter earlier than the conventional one. Also, the anomaly detection device according to the second embodiment can detect an anomaly of the ultrasonic flowmeter in real time while the ultrasonic flowmeter is performing measurement.

[0059] It should be noted that, within the scope of the present invention, the embodiments may be freely combined, any component of each embodiment may be modified, or any component of each embodiment may be omitted. [Explanation of symbols]

[0060] 1 Measuring tube 2. Ultrasonic Sensor 3. Ultrasonic Sensor 4 Arithmetic section 401 received signal acquisition unit (first received signal acquisition unit) 402 received signal acquisition unit (second received signal acquisition unit) 403 Zero-crossing point measurement unit (first zero-crossing point measurement unit) 404 Zero-crossing point measurement unit (second zero-crossing point measurement unit) 405 Time Difference Calculation Unit 406, 406b Average value calculation unit (first average value calculation unit) 407, 407b Average value calculation unit (second average value calculation unit) 408,408b Difference calculation part 409,409b Anomaly detection section 410 Flow rate calculation section

Claims

1. a first reception signal acquisition unit that acquires a reception signal received by one of the ultrasonic sensors included in the ultrasonic flowmeter; a second reception signal acquisition unit that acquires a reception signal received by the other ultrasonic sensor of the ultrasonic flowmeter; a first zero-crossing point measurement unit that measures a time from a start of transmission to a zero-crossing point multiple times for each of multiple unit measurement steps based on an acquisition result by the first received signal acquisition unit; a second zero-crossing point measurement unit that measures a time from a start of transmission to a zero-crossing point multiple times for each of multiple unit measurement steps based on an acquisition result by the second received signal acquisition unit; a time difference calculation unit that calculates a time difference between a measurement result by the first zero cross point measurement unit and a measurement result by the second zero cross point measurement unit; a first average value calculation unit that calculates an average value of time differences at a first half zero crossing point based on a calculation result by the time difference calculation unit; a second average value calculation unit that calculates an average value of time differences at a second zero crossing point based on a calculation result by the time difference calculation unit; a difference calculation unit that calculates an absolute value of a difference between a calculation result by the first average value calculation unit and a calculation result by the second average value calculation unit; an abnormality detection unit that detects an abnormality in the ultrasonic flowmeter by comparing the absolute value of the difference calculated by the difference calculation unit with a threshold value; An anomaly detection device equipped with the above.

2. a first reception signal acquisition unit that acquires a reception signal received by one of the ultrasonic sensors included in the ultrasonic flowmeter; a second reception signal acquisition unit that acquires a reception signal received by the other ultrasonic sensor of the ultrasonic flowmeter; a first zero-crossing point measurement unit that measures a time from a start of transmission to a zero-crossing point multiple times for each of multiple unit measurement steps based on an acquisition result by the first received signal acquisition unit; a second zero-crossing point measurement unit that measures a time from a start of transmission to a zero-crossing point multiple times for each of multiple unit measurement steps based on an acquisition result by the second received signal acquisition unit; a first average value calculation unit that calculates an average value of a time of a first half zero cross point based on a measurement result by the first zero cross point measurement unit and a measurement result by the second zero cross point measurement unit; a second average value calculation unit that calculates an average value of a time of a second half zero cross point based on the measurement result by the first zero cross point measurement unit and the measurement result by the second zero cross point measurement unit; a difference calculation unit that calculates an absolute value of a difference between a calculation result by the first average value calculation unit and a calculation result by the second average value calculation unit; an abnormality detection unit that detects an abnormality in the ultrasonic flowmeter by comparing the absolute value of the difference calculated by the difference calculation unit with a threshold value; An anomaly detection device equipped with the above.

3. The first average value calculation unit calculates a final average value by repeating the calculation of the average value N times and averaging the results, The second average value calculation unit calculates a final average value by repeating the calculation of the average value N times and averaging the results.

3. The abnormality detection device according to claim 1 or 2.

4. A step in which a first reception signal acquisition unit acquires a reception signal received by one of the ultrasonic sensors included in the ultrasonic flowmeter; A step in which a second reception signal acquisition unit acquires a reception signal received by the other ultrasonic sensor of the ultrasonic flowmeter; a first zero-crossing point measuring unit measuring a time from a start of transmission to a zero-crossing point multiple times for each of multiple unit measurement steps based on an acquisition result by the first received signal acquiring unit; a second zero-crossing point measuring unit measuring a time from a start of transmission to a zero-crossing point multiple times for each of multiple unit measurement steps based on an acquisition result by the second received signal acquiring unit; A time difference calculation unit calculates a time difference between a measurement result by the first zero cross point measurement unit and a measurement result by the second zero cross point measurement unit; A first average value calculation unit calculates an average value of time differences at first zero crossing points based on a calculation result by the time difference calculation unit; A second average value calculation unit calculates an average value of time differences at a second zero crossing point based on a calculation result by the time difference calculation unit; A difference calculation unit calculates an absolute value of a difference between a calculation result by the first average value calculation unit and a calculation result by the second average value calculation unit; an abnormality detection unit detecting an abnormality in the ultrasonic flowmeter by comparing the absolute value of the difference calculated by the difference calculation unit with a threshold value; The anomaly detection method includes the steps of:

5. A step in which a first reception signal acquisition unit acquires a reception signal received by one of the ultrasonic sensors included in the ultrasonic flowmeter; A step in which a second reception signal acquisition unit acquires a reception signal received by the other ultrasonic sensor of the ultrasonic flowmeter; a first zero-crossing point measuring unit measuring a time from a start of transmission to a zero-crossing point multiple times for each of multiple unit measurement steps based on an acquisition result by the first received signal acquiring unit; a second zero-crossing point measuring unit measuring a time from a start of transmission to a zero-crossing point multiple times for each of multiple unit measurement steps based on an acquisition result by the second received signal acquiring unit; A first average value calculation unit calculates an average value of a time of a first half zero cross point based on a measurement result by the first zero cross point measurement unit and a measurement result by the second zero cross point measurement unit; A second average value calculation unit calculates an average value of a time of a latter zero cross point based on the measurement result by the first zero cross point measurement unit and the measurement result by the second zero cross point measurement unit; A difference calculation unit calculates an absolute value of a difference between a calculation result by the first average value calculation unit and a calculation result by the second average value calculation unit; an abnormality detection unit detecting an abnormality in the ultrasonic flowmeter by comparing the absolute value of the difference calculated by the difference calculation unit with a threshold value; The anomaly detection method includes the steps of:

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