JP5531993B2 - Flow measuring device - Google Patents

Description

  The present invention relates to a flow rate measuring device that detects, in an initial stage, that condensation occurs in a gas passage in a flow rate measuring device and measurement accuracy deteriorates.

  Conventionally, this type of flow rate measuring device is described in the prior art document as a configuration described in Patent Document 1.

  FIG. 5 shows a conventional flow rate measuring device described in Patent Document 1. As shown in FIG.

  As shown in FIG. 5, the conventional flow rate measuring device includes a signal detection unit 11, a flow rate calculation unit 12, an abnormal flow rate determination unit 13, a valve drive unit 14, a valve 15, a sensor output correction unit 16, a sensor abnormality determination unit 17, and a notification. Part 18. The role is described below.

  In addition to outputting the flow rate signal a, the signal detector 11 indicates whether or not the flow rate signal a and the gain value are appropriate for the gas flow rate passing through the gas passage based on the corrected gain value f. An appropriate signal e is output. The flow rate calculation unit 12 calculates the flow rate b using the flow rate signal a of the signal detection unit 11. The abnormal flow rate determination unit 13 compares the flow rate b of the flow rate calculation unit 12 with a determination value held in advance, and outputs a valve closing signal c if abnormal. The valve drive unit 14 outputs the valve drive signal d if there is a valve closing signal c of the abnormal flow rate determination unit 13 or the sensor abnormality determination unit 17. The valve 15 closes the gas passage based on the valve drive signal d of the valve drive unit 14. The sensor output correction unit 16 controls (corrects) the gain value of the ultrasonic wave and outputs the gain value f when the gain appropriate signal e of the signal detection unit 11 is not appropriate. When the sensor abnormality determination unit 17 exceeds the first predetermined value or falls below the third predetermined value, the sensor abnormality determination unit 17 outputs the first alarm signal g1 that is not accompanied by the output of the valve closing signal c, and is higher than the first predetermined value. When the second predetermined value is exceeded or when it falls below a fourth predetermined value lower than the third predetermined value, a second alarm signal g2 accompanied by the output of the valve closing signal c is output. The notification unit 18 notifies the outside based on the first alarm signal g1 or the second alarm signal g2 of the sensor abnormality determination unit 17.

  Moreover, the ultrasonic wave output from the transmission side sensor of the ultrasonic flow measuring device is received by the reception side sensor. The received waveform is shown in FIG. In FIG. 7A, the first zero cross point after the signal level of the received waveform exceeds the threshold value V is measured as the reception point. The propagation time T is measured by measuring the time from transmission to reception. In addition, the gain value is corrected each time so that the maximum peak of the received waveform falls between the peak upper limit value VH and the peak lower limit value VL, which are preset values, and the third wave of the received waveform always has the V level for the first time. I try to exceed.

  Here, since the correction of the gain value cannot be performed physically without limitation, when the limit of the allowable range that can be corrected is approached, an alarm is issued to alert the user. When the limit point is reached, no further correction of the gain value is possible, so the gas passage is closed to ensure security and measurement performance.

That is, as shown in FIG. 7 (d), the flow rate measuring device has an alarm level (first predetermined value) that does not involve closing of the gas passage and a shut-off level (second predetermined value) at which the gas passage is closed by the valve closing signal c. Is provided to monitor the correction of the gain value. There are a plurality of factors that increase (increase) the gain value. First, it is a well-known fact that the reception waveform (reception waveform in FIG. 7A) decreases as the passage speed (flow velocity) of the gas flowing through the gas passage increases. It is. Some are due to aging. For example, as shown in FIGS. 7B and 7C, dust (z), which is dust or dust mixed during gas piping work, adheres to the mesh (w), thereby receiving an ultrasonic waveform. It is a factor that attenuates. As shown in FIG. 7B, the mesh (w) means that the ultrasonic wave passes through the side surface of the flow path when the ultrasonic sensor (v) is installed at an angle θ with respect to the central axis of the gas passage. (This mesh (w) prevents the measurement accuracy from being lowered due to vortices generated by the gas passing through the opening.) To be installed).

  On the other hand, a flow path dividing plate (x) is incorporated in the gas passage as shown in FIG. 7 (b) or FIG. 7 (c) in order to stabilize the gas flow. As shown in FIG. 7C, the flow path dividing plate (x) is installed so as not to interfere with transmission / reception of the ultrasonic sensor (v), and is configured by providing a plurality of plates. This has the function of smoothing and stabilizing the gas flow.

JP 2005-315717 A

  However, when the temperature of the flow measuring device is lower than the temperature of the gas in winter, etc., that is, the gas pipe installed upstream from the flow measuring device is buried in the ground, so even compared with winter. In contrast to a warm environment, the flow measuring device may be exposed to the outside air and cooled down. When moisture is mixed in the gas in an environment where such a temperature difference occurs, the wet gas flows into the cold flow rate measuring device and condensation occurs. For example, the case where the rainwater etc. which were not able to be extracted at the time of gas piping construction remain, and the gas which was originally dried has absorbed the water | moisture content etc. are mentioned. As shown in FIG. 7 (c), if a large amount of condensed water (y) is generated on the upper and lower surfaces of each of the flow dividing plates (x), the passage area of the gas passage is reduced. As a result, the gain value increases as described above.

  As shown in Fig. 7 (d), the dust gradually adheres to the mesh, so the gain value gradually increases in units of months (or years), whereas condensation occurs due to the inflow of wet gas. Therefore, the gain value increases rapidly in units of time (or days) and the passage area decreases, thereby causing instrumental error (deterioration of measurement accuracy) as shown in FIG. In the system in which gas flows from the left to the right in FIG. 8, the instrumental error is the inside of the gas passage of the flow rate measuring device in which moisture is included in the gas by a humidifier and sufficiently cooled in the cooling device. Condensation (including flow dividing plate) is generated, moisture in the gas that has not been fully condensed by the dehumidifier is removed, and accurate gas usage is performed with a reference device that is not affected by condensation due to the loss of gas moisture When the amount is measured, the difference (deviation) between the amount of gas used measured by the reference device and the amount of gas used measured by the flow measurement device is assumed to be a ratio.

This is because when the flow rate measuring device counts the amount of gas used, as shown in FIG. 7B, if the sound velocity in the stationary gas is c and the gas flow velocity is v, the ultrasonic wave in the forward direction of the flow The propagation speed is (c + v). When the distance between the ultrasonic sensors facing each other is L, and the angle θ between the ultrasonic wave propagation axis and the central axis of the gas passage, the time T that the ultrasonic wave reaches is:
T = L / (c + vCOSθ) (1)
From the equation (1), v = (L / Tc) / COSθ (2)
If L and θ are known, the flow velocity v can be obtained by measuring T.

From this flow velocity v, the gas usage amount Q can be calculated by assuming that the passage area is S and the correction coefficient is K.
Q = KSv (3)
It becomes. The flow rate measuring device does not obtain the passage area S each time the gas usage amount Q is measured, but holds it as a constant known value. For this reason, actually, even if the passage area S is reduced due to the dew condensation water, the flow measuring device cannot be detected. Therefore, the gas usage amount Q is obtained based on a constant passage area S of the same size, and as a result, the gas usage amount Q increases as the flow velocity v increases (because the passage area S is a known constant value). As a result, instrumental error will occur.

  From the above, if condensed water is generated on the flow dividing plate, it causes instrumental error and counts the amount of gas used more than the actual amount of gas used. Had the problem of being done.

  In the present invention, the gas user can always detect himself / herself by detecting an abnormality within the allowable error range even when condensed water is generated in the gas passage (flow path dividing plate) of the flow measuring device in winter. An object of the present invention is to provide a flow rate measuring device capable of paying an appropriate gas fee based on the amount used by the.

In order to solve the above-described conventional problem, in the flow rate measuring device of the present invention, a period correction determination unit determines whether there is a gain value greater than or equal to a predetermined value and an increase during a predetermined period, and the period correction determination unit If the rate of increase of the value is greater than or equal to the predetermined value, the flow path is shut off if it continues for a predetermined number of times. The reference value is updated at

  As a result, it is possible to avoid the fact that the gain value has not been detected until it reaches the alarm level or the cutoff level.

  The flow rate measuring device of the present invention can determine whether or not the gain value has increased by a predetermined value or more during a predetermined period, and can determine whether or not the gain value has increased in a short period. Therefore, by making it possible to detect a sudden increase in the gain value due to condensed water before reaching the alarm level or shut-off level, it is possible to detect the occurrence of instrumental error due to condensed water at an early stage, and within the range of allowable instrumental error. It is possible to measure the amount of gas used, and to calculate an appropriate gas charge. In addition, since it is not necessary to change the alarm level or the cutoff level, the reliability of the system can be improved without impairing convenience and economy.

Functional block diagram of a flow rate measuring device according to Embodiments 1, 2, and 3 of the present invention Flowchart in Embodiment 1 of the present invention Flowchart in Embodiment 2 of the present invention Flowchart in Embodiment 3 of the present invention Functional block diagram of a conventional flow measurement device (A) Determination schematic diagram of period correction determination unit of Embodiment 1 of the present invention, (b) Determination schematic diagram of period correction determination unit of Embodiment 2 of the present invention, (c) Embodiment 3 of the present invention Schematic of determination by the period correction determination unit (A) Reception waveform diagram of ultrasonic waves to be transmitted / received, (b) Outline diagram of measurement unit in conventional flow rate measurement device, (c) Outline diagram of measurement unit in conventional flow rate measurement device, (d) Condensation and dust generation (E) Gain value time characteristic diagram when condensation occurs System diagram of an experimental device for measuring instrumental error

In the first invention, when a reception waveform of a propagation wave transmitted and received by a pair of ultrasonic sensors provided in a flow path is detected and amplified so that the maximum peak of the reception waveform falls within a predetermined range. A signal detection unit that outputs a gain value; a flow rate calculation unit that calculates a flow rate by measuring a propagation time of the propagation wave of the signal detection unit; a notification unit that notifies an alarm to the outside; and the gain value A sensor abnormality determination unit that outputs an alarm signal to the notification unit when the alarm level exceeds a preliminarily held alarm level, and is determined in advance when the gain value does not exceed the alarm level in the sensor abnormality determination unit. A period correction determination unit that determines whether or not there is an abnormality by determining whether or not an increase rate of the gain value within a predetermined time is equal to or greater than a predetermined value, and includes a blocking unit that blocks the flow path , Said period supplement The determination unit is configured to block the flow path when the increase rate of the gain value is equal to or greater than a predetermined value in the determination, and when the increase rate of the gain value is equal to or greater than the predetermined value. If it does not occur repeatedly, the reference value is updated without blocking the flow path .

  According to this, it becomes possible for the period correction determination unit to detect a sudden increase in the gain value before reaching the alarm level or the cutoff level. As a result, it is possible to ensure safety and at the same time not impair the convenience and economy of the flow rate measuring device.

In a second aspect of the invention, particularly in the first aspect of the invention, the sensor abnormality determination unit causes the blocking unit to block the flow path when the gain value exceeds a blocking level higher than the alarm level. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows a functional block diagram of a flow rate measuring apparatus according to Embodiment 1 of the present invention.

  In FIG. 1, the flow rate measuring apparatus according to the first embodiment includes a signal detection unit 11, a flow rate calculation unit 12, an abnormal flow rate determination unit 13, a valve drive unit 14, a valve 15, a sensor output correction unit 16, a sensor abnormality determination unit 17, and a notification. The unit 18 and the period correction determination unit 19 are described below.

  The signal detection unit 11 corresponds to the gas flow rate passing through the gas passage based on a correction gain value F such that the maximum peak of the received waveform falls between the peak upper limit value VH and the peak lower limit value VL, which are preset values. Then, an appropriate gain signal E indicating whether the flow rate signal A and the gain value F are appropriate is output. Specifically, if the maximum peak of the received waveform is between VH and VL, it is determined to be appropriate.

The flow rate calculation unit 12 calculates the flow rate B using the flow rate signal A of the signal detection unit 11. Specifically, as described above, the gas usage amount Q is obtained by multiplying the flow velocity v by the coefficient of the passage area S and the correction coefficient K.

  The abnormal flow rate determination unit 13 compares the determination value stored in advance using the flow rate B of the flow rate calculation unit 12 and outputs a valve closing signal C if abnormal. For example, when the flow rate B exceeds the maximum amount of gas that can be passed per unit time Q1 allowed by the flow measurement device, or when a small amount of gas usage Q2 continues to flow and exceeds the allowable time There is a case.

  The valve drive unit 14 outputs a valve drive signal D using the valve closing signal C from the abnormal flow rate determination unit 13, the sensor abnormality determination unit 17, or the period correction determination unit 19. The valve 15 closes the gas passage using the valve drive signal D.

  The sensor output correction unit 16 determines whether or not the appropriate gain signal E of the signal detection unit 11 is appropriate, and corrects and outputs the gain value F to an appropriate value when the appropriate gain signal E is not appropriate. For example, as described above, correction may be performed so that the maximum peak of the received waveform falls between VH and VL.

  The sensor abnormality determination unit 17 outputs an alarm signal G if the gain value F of the sensor output correction unit 16 exceeds the alarm level held in advance. Thereby, it is possible to notify the gas supplier and the gas user that the correction amount of the gain value F has increased before reaching the cutoff level.

  Further, if the gain value F exceeds the pre-held cutoff level, the valve closing signal C is output. As the blocking level, the determination value of the blocking level may be set as high as possible in consideration of convenience and economy within a range in which security and measurement performance can be ensured. For example, when the normal normal gain value correction amount is 40, the cutoff level determination value can be set to 100.

  When the notification unit 18 receives the warning signal G from the sensor abnormality determination unit 17, the notification unit 18 issues a warning to the outside. For example, the notification unit 18 may be configured to display an LCD or LED provided on a flow rate measuring device, or may be configured to notify a gas user or a gas supplier by wired communication, wireless communication, an Internet line, or the like.

  The period correction determination unit 19 checks the increase amount of the gain value F of the sensor output correction unit 16 within a predetermined period as shown in FIG. 6A, and determines whether or not the increase amount is equal to or greater than a predetermined value. . If the gain value F increases beyond a predetermined value, the valve closing signal C is output, and if the gain value F does not increase above the predetermined value, the valve closing signal C is not output and the reference value is updated during a predetermined period. The increase determination of the gain value F equal to or greater than the predetermined value is performed again. For the predetermined period, a method of periodically changing the starting point may be used. Further, monitoring for a predetermined period may be performed from the time when the microcomputer controlling the flow rate measuring device starts after resetting, or monitoring for the predetermined period may be started from the time when a certain gain value is reached. The reference value is a gain value at the start of monitoring. Next, when the amount of gas used is within a predetermined value, it is determined whether or not the gain value F has increased by a certain value or more. If the gain value F increases beyond a predetermined value, the valve closing signal C is output, and if the gain value F does not increase above the predetermined value, the valve closing signal C is not output and the reference value is updated during a predetermined period. The increase determination of the gain value F equal to or greater than the predetermined value is performed again. In addition, it is good also as a structure which alert | reports using a communication means or a display means instead of outputting the valve closing signal C. Further, the increase determination may be performed depending on whether or not the gain value F when the gas is not used is increased by a certain value or more.

  As described above, in the present embodiment, the period correction determination unit 19 can detect an abrupt increase in the gain value F before reaching the alarm level or the cutoff level. The convenience and economics can be maintained.

  FIG. 2 shows a flowchart of the first embodiment. The period correction determination unit 19 acquires, as an initial reference value, the gain value F when the microcomputer that controls the flow rate measuring device is reset and activated (processing S01). The gain value after a lapse of a certain time from the startup may be used as the reference value.

  Next, the flow rate calculation unit 12 calculates the flow rate using the gas flow rate signal acquired in the signal detection unit 11 (processing S02). The flow rate calculation unit 12 obtains a gas usage amount from the flow rate calculated in the process S02 (process S03).

  Next, the abnormal flow rate determination unit 13 compares the flow rate calculated by the flow rate calculation unit 12 with a determination value held in advance to determine whether there is an abnormality (processing S04). If it is determined that there is an abnormality, the process proceeds to process S13, and if it is determined that there is no abnormality, the process proceeds to process S05. As the determination value, it is desirable to use the maximum amount Q of gas that can be passed per unit time allowed by the flow rate measuring device. Note that the process S04 is not limited to this configuration, and measures the time that the flow rate of a certain value or more has continued, and determines that the measured time exceeds a predetermined allowable time as an abnormality. It is good also as composition to do.

  If it is determined in step S04 that there is no abnormality, the sensor output correction unit 16 corrects the gain value F (step S05). For example, as described above, the maximum peak of the received waveform is corrected so as to be between VH and VL.

  Next, the sensor abnormality determination unit 17 determines whether the gain value F exceeds a predetermined cutoff level (for example, 100). If the gain value F exceeds the cutoff level, the process proceeds to step S13. If the gain value F does not exceed the cutoff level, the process proceeds to process S07 (process S06).

  The sensor abnormality determination unit 17 determines whether the gain value F exceeds a predetermined alarm level (for example, 80) (process S07). If the gain value F exceeds the alarm level, the process proceeds to process S08. If the gain value F does not exceed the alarm level, the process proceeds to step S09.

  When it is determined by the sensor abnormality determination unit 17 that there is an abnormality, the notification unit 18 issues a warning to the outside (processing S08), and proceeds to processing S09. The notification unit 18 may have a form in which an LCD or LED is provided on the flow measurement device and displays it, or makes a report (regardless of wired / wireless) to a gas user or a gas supplier by public communication means or dedicated communication means. Form may be sufficient. Moreover, you may report via an internet line etc.

  The period correction determination unit 19 determines whether a predetermined period (for example, one week) has elapsed from a predetermined starting point (processing S09). If the predetermined period has elapsed, the process proceeds to step S10. If the predetermined period has not elapsed, the process proceeds to process S02. Moreover, the method of changing a starting point regularly may be used. The starting point may be the time when the microcomputer controlling the flow rate measuring device starts after resetting, or may be the time when a certain gain value is reached.

  When the predetermined period has elapsed in the process S09, the period correction determination unit 19 determines an increase in the gain value F equal to or greater than the predetermined value (process S10). If there is an increase in the gain value F greater than or equal to the predetermined value, the process proceeds to step S13, and if there is no increase in the gain value F greater than or equal to the predetermined value, the process proceeds to step S11. Note that, in steps S09 to S10, it is determined whether or not there is a gain increase of a predetermined value or more within a predetermined period. However, when the amount of gas used is within a predetermined value or when no gas is used. A configuration may be used in which it is checked whether the gain value F is increased by a predetermined value or more.

  If the predetermined period has not elapsed in the process S09, the time counter for the predetermined period is cleared and the process proceeds to the process S12 (process S11). Then, the reference value is updated (process S12), and the process proceeds to process S02.

  In the process S13, the valve drive unit 14 outputs the valve drive signal D, and the valve 15 closes the gas passage. In addition, although it was set as the structure which drives a valve in this Embodiment, it is good also as a structure which alert | reports using a communication means or a display means.

  In the above flow, an increase in gain value equal to or greater than a predetermined value is determined after a predetermined period has elapsed. However, if the order of the processing in steps S09 and S10 is reversed, the predetermined value is increased when there is a predetermined increase in gain. It can be configured to determine whether or not a period of time or more has elapsed.

(Embodiment 2)
FIG. 1 is a functional block diagram of a flow rate measuring apparatus according to Embodiment 2 of the present invention.

  In FIG. 1, the flow rate measuring device according to the second embodiment includes a signal detection unit 11, a flow rate calculation unit 12, an abnormal flow rate determination unit 13, a valve drive unit 14, a valve 15, a sensor output correction unit 16, a sensor abnormality determination unit 17, and a notification. Unit 18 and period correction determination unit 29. Since the configuration other than the period correction determination unit 29 is the same as that of the first embodiment, the description thereof is omitted. The role of the period correction determination unit 29 will be described below.

  The period correction determination unit 29 uses the gain value F of the sensor output correction unit 16 to determine whether or not the gain value F is greater than or equal to a predetermined value during a predetermined period, as shown in FIG. 6B. If there is a gain increase greater than a predetermined value, the number of times is counted. Then, if a gain increase of a predetermined value or more occurs continuously for a predetermined number of times, it is determined as abnormal and a valve closing signal C is output. If an increase of the gain value F of a predetermined value or more does not occur continuously for a predetermined number of times, C does not output, updates the reference value, and repeats the continuous determination of an increase in gain value F that is greater than or equal to a predetermined value during a predetermined period.

  As described above, in the present embodiment, the period correction determination unit 29 detects a predetermined number of consecutive increases in the gain value F, thereby ensuring safety and at the same time impairing the convenience and economy of the flow rate measuring device. Therefore, it is possible to expedite detection of dew condensation that occurs during the predetermined period. It should be noted that by making the magnitude of the predetermined period and the gain increase / decrease determination value small, it is possible to make a determination with higher safety.

  FIG. 3 shows a flowchart of the second embodiment. Since the operations with the same processing numbers as those in the flowchart of the first embodiment other than those described below are the same, the description thereof will be omitted.

  The period correction determination unit 29 determines whether a predetermined period (for example, one week) has elapsed from a predetermined starting point (processing S09). If the predetermined period has elapsed, the process proceeds to step S10. If the predetermined period has not elapsed, the process proceeds to process S02.

  When the predetermined period has elapsed in the process S09, the period correction determination unit 29 determines an increase in the gain value F equal to or greater than the predetermined value (process S10). If there is an increase in the gain value F greater than or equal to the predetermined value, the process proceeds to step S14, and if there is no increase in the gain value F greater than or equal to the predetermined value, the process proceeds to process S11.

When it is determined in process S10 that the gain value F has increased by a predetermined value or more, the period correction determination unit 29 counts the number of times the gain value F has increased by a predetermined value or more. Then, it is determined whether or not the count number has reached a predetermined number (step S14). If the predetermined number has been reached, the process proceeds to step S13, and if the predetermined number has not been reached, the process proceeds to step S11.

  In step S11, the time counter for a predetermined period and the counter for the predetermined number of times are cleared, and the process proceeds to step S12.

  In the above flow, an increase in gain value equal to or greater than a predetermined value is determined after a predetermined period has elapsed. However, if the order of the processing in steps S09 and S10 is reversed, the predetermined value is increased when there is a predetermined increase in gain. It can be configured to determine whether or not a period of time or more has elapsed.

(Embodiment 3)
FIG. 1 is a functional block diagram of a flow rate measuring apparatus according to Embodiment 3 of the present invention.

  In FIG. 1, the flow rate measurement device according to the third embodiment includes a signal detection unit 11, a flow rate calculation unit 12, an abnormal flow rate determination unit 13, a valve drive unit 14, a valve 15, a sensor output correction unit 16, a sensor abnormality determination unit 17, and a notification. Unit 18 and a period correction determination unit 39. Except for the period correction determination unit 39, it is the same as that of the first embodiment, and a description thereof will be omitted. The role of the period correction determination unit 39 will be described below.

  The period correction determination unit 39 uses the gain value F of the sensor output correction unit 16 as shown in FIG. 6C and after the first predetermined period (for example, one week) has elapsed and the second predetermined period (for example, The presence / absence of an increase in the gain value F greater than or equal to a predetermined value is determined a predetermined number of times (e.g., three times) every day. If the gain value F increases by a predetermined number or more, a valve closing signal C is output. If there is no increase in the gain value F exceeding the predetermined value even once, the reference value is updated without outputting the valve closing signal C, and the gain value exceeding the predetermined value is passed after the first predetermined period and every time the second predetermined period elapses. Redo the determination of the predetermined number of increases in F.

  As described above, in the present embodiment, the period correction determination unit 39 determines the continuous determination period according to the second embodiment by determining the predetermined number of times based on the combination after the first predetermined period and the second predetermined period. Further shortening is possible.

  FIG. 4 shows a flowchart of the third embodiment. Since the operations with the same processing numbers as those in the flowchart of the first embodiment are the same, the description thereof is omitted.

  The period correction determination unit 39 determines whether a predetermined period (for example, one week) has elapsed from a predetermined starting point (processing S09). If the predetermined period has elapsed, the process proceeds to step S15. If the predetermined period has not elapsed, the process proceeds to step S02. In step S09, it is determined whether the predetermined period has elapsed. If the predetermined period has elapsed, the process proceeds to process S15. If the predetermined period has not elapsed, the process proceeds to process S02.

  The process S15 determines whether or not a second predetermined time (for example, one day) has elapsed. If the second predetermined time has elapsed, the process proceeds to the process S10, and if the second predetermined time has not elapsed. The process proceeds to process S02. Note that the measurement starting point of the second predetermined time may be the time when the first predetermined time has elapsed.

  As described above, by monitoring the gain value F in the first to third embodiments, it is possible to detect an instrumental error, which is a deterioration in measurement accuracy due to condensation, at an acceptable initial stage, and at the same time guaranteeing safety, the flow rate is guaranteed. It is possible to prevent the convenience and economy of the measuring device from being impaired. Furthermore, in Embodiments 2 to 3, when condensation occurs during a predetermined period, the presence or absence of condensation can be detected earlier.

  The present invention specializes in gain value changes due to condensation in gas flow measurement using ultrasonic waves, but is not limited to this and is applicable if there is a phenomenon that can be determined by changes in gain values. Is possible.

DESCRIPTION OF SYMBOLS 11 Signal detection part 12 Flow rate calculation part 13 Abnormal flow rate determination part 14 Valve drive part 15 Valve (blocking part)
16 Sensor output correction unit 17 Sensor abnormality determination unit 18 Notification unit 19, 29, 39 Period correction determination unit

Claims (2)

A signal that outputs a gain value when a received waveform of a propagation wave transmitted and received by a pair of ultrasonic sensors provided in a flow path is detected and amplified so that the maximum peak of the received waveform falls within a predetermined range. A detection unit;
A flow rate calculation unit that calculates a flow rate by measuring a propagation time of the propagation wave of the signal detection unit;
A notification unit that issues a warning to the outside,
A sensor abnormality determination unit that outputs an alarm signal to the notification unit when the gain value exceeds an alarm level held in advance;
Presence or absence of abnormality by determining whether or not the increase rate of the gain value within a predetermined time is greater than or equal to a predetermined value when the gain value does not exceed the alarm level in the sensor abnormality determination unit A period correction determination unit for determining
A blocking portion for blocking the flow path;
The period correction determination unit shuts off the flow path when the increase rate of the gain value is equal to or greater than a predetermined value in the determination, and the gain value increase rate is equal to or greater than the predetermined value. A flow rate measuring device that updates a reference value without blocking the flow path if the case does not continuously occur a predetermined number of times . The flow rate measurement device according to claim 1 , wherein the sensor abnormality determination unit causes the blocking unit to block the flow path when the gain value exceeds a blocking level higher than the alarm level.