JP2008128824A - Ultrasonic flow meter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic flow meter that will not cause wrong determination of equipment abnormalities and flow rate abnormalities, by speedily and accurately detecting a mixture of air and gas in fluid in a flow passage. <P>SOLUTION: The ultrasonic flowmeter has a pair of ultrasonic vibrators 110a, 110b installed separated by a fixed distance on the upstream side and on the downstream side of a gas flow passage 100c, in which a fluid to be measured flows; a time measurement means for measuring the propagation time of an ultrasonic signal which is transmitted and received between the pair of the ultrasonic vibrators; and a flow rate measurement means for measuring the flow rate of the fluid to be measured, based on the propagation time measured by the time measurement means. The ultrasonic flow meter includes a temperature sensor 160 for measuring the temperature in the gas flow passage 100c; a storing part 120 for storing, in advance, the propagation time data corresponding to the temperature of the fluid, when there is no mixture occurring in the fluid to be measured; and a mixture detection means for detecting whether a mixture is occurring in the fluid to be measured, based on the propagation time data stored by the storing part 120 and the propagation time measured by the time measurement means which corresponds to the temperature measured by the temperature sensor 160. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasonic flowmeter having a function of measuring the flow rate of gas and diagnosing the mixing of other fluids.

  Conventionally, a pair of ultrasonic transducers are provided at a certain distance on the upstream side and downstream side of the flow path, and the ultrasonic signal is transmitted and received between them repeatedly. 2. Description of the Related Art An ultrasonic flowmeter that obtains a flow rate based on a difference between a propagation integration time of a sound wave signal and a propagation integration time from a downstream side to an upstream side is known.

  In such a conventional ultrasonic flow measurement, by measuring in a state where a fluid other than gas is mixed in the flow path, an erroneous determination is made that a flow abnormality has occurred, and an ultrasonic flow meter device abnormality, etc. There has been a problem of misjudgment.

  In the ultrasonic flow meter described above, the flow path is filled with air when the ultrasonic flow meter is shipped from the factory, and when the ultrasonic flow meter is installed, the gas is installed by a gas instrument installed downstream of the ultrasonic flow meter. It is necessary to perform an operation of consuming the gas and filling the flow path with gas. In the state where air and gas are mixed while the flow path is filled with gas, the accurate flow velocity cannot be measured, and erroneous judgments such as abnormalities in ultrasonic flowmeter equipment are made from abnormal flow velocity measurements. There is a fear.

  Therefore, there is a flow rate measuring device that stops the determination of the flow rate abnormality while it can be determined that the air and gas are mixed (see, for example, Patent Document 1).

  FIG. 14 shows an electronic gas meter in which a flow rate measuring device disclosed in Patent Document 1 is incorporated. The illustrated electronic gas meter is configured as an ultrasonic type, and is arranged so as to be opposed to each other so as to be separated by a distance L in the gas flow path and at an angle θ with respect to the gas flow direction Y. There are two acoustic transducers TD1 and TD2.

  The two acoustic transducers TD1 and TD2 are composed of, for example, piezoelectric vibrators that operate at an ultrasonic frequency. The gas flow path is provided with a gas shut-off valve 10 that shuts off the gas flow path by closing the valve upstream of the two acoustic transducers TD1 and TD2.

  Next, the operation of the electronic gas meter having the configuration shown in FIG. 14 will be described. The μCOM 14 measures the gas flow rate at each sampling time using the two transducers TD1 and TD2, and performs an instantaneous flow rate measurement process of measuring the instantaneous flow rate by multiplying the measured gas flow rate by the cross-sectional area of the gas flow path.

  Assuming that the sound velocity is c and the gas flow velocity is v, the propagation speed of the ultrasonic signal from the transducer TD1 to the transducer TD2 is (c + v cos θ), and the propagation speed of the ultrasonic signal from the transducer TD2 to the transducer TD1 is (c− vcos θ). Therefore, when L and θ are known, the flow velocity v can be obtained by measuring the bidirectional transmission time of the ultrasonic signal.

  The instantaneous flow rate can be obtained by multiplying the gas flow velocity v by the cross-sectional area of the gas flow path.

  Further, the μCOM 14 performs a return process for confirming the return safety of the gas shut-off valve after the shipment mode is released. The electronic gas meter is set in a shipping mode in which the power consumption state is lower than normal and the gas shut-off valve 10 is in a closed state until the electronic gas meter is shipped from the factory and installed at the installation site. When the shipping mode canceling operation is performed by operating a magnet switch or the like, the μCOM 14 starts the above-described return processing. At that time, the μCOM 14 first functions as a mixture determination unit and a stop unit, and after the shipping mode release operation, based on the reception state of the ultrasonic signal and the instantaneous flow rate calculated by the ultrasonic signal, Until no mixing is detected, it is determined that a mixed state has occurred, and stop processing is performed to stop the determination of the flow rate abnormality.

  After exiting this stop process, the μCOM 14 functions as an abnormality determination unit and a return safety confirmation unit, restarts the determination of the flow rate abnormality, and performs the return safety confirmation process based on the flow rate abnormality determination. In this way, by providing a stop process, the instantaneous flow rate (= flow velocity) cannot be accurately measured. During the mixture of supply gas and air, it is determined that the flow rate is abnormal based on the measured flow rate, and the return safety confirmation process As a result, the gas shut-off valve 10 is not closed. Therefore, it is possible to prevent the gas shut-off valve 10 from being unable to be restored after the shipment mode is released even though the flow rate abnormality has not occurred.

  In performing the above-described stop process, two kinds of determinations are made. One is to perform measurement abnormality determination processing for transmission / reception of ultrasonic signals performed by the latest instantaneous flow rate measurement processing, and determine whether or not a measurement abnormality that cannot accurately measure the flow velocity has occurred. The abnormal measurement here refers to a case where, for example, even if the gain of a transmission ultrasonic signal is maximized, a phenomenon occurs in which an ultrasonic signal having a reception level exceeding a threshold cannot be received on the reception side.

  Another determination method is to determine whether or not the instantaneous flow rate fluctuates. Specifically, if the difference between the instantaneous flow rate obtained by the latest instantaneous flow rate measurement process and the instantaneous flow rate obtained by the previous instantaneous flow rate measurement process is less than or equal to a certain value, it is determined that there is no fluctuation and is constant. If the value is exceeded, it is determined that the value has fluctuated.

  If the measurement abnormality or flow rate fluctuation continues for a long time, the measurement abnormality or flow rate fluctuation does not occur due to the mixed gas, but the measurement is actually caused by the failure of the transducers TD1 and TD2. When it is determined that an abnormality has occurred, the process again shifts to the shipping mode, and the process ends.

  The above determination method is based on the fact that there is a high possibility that a state in which the flow velocity cannot be measured due to the mixture of supply gas and air.

  Next, a return safety confirmation process when the stop process described above is performed will be described. In this case, if the passage flow rate obtained by the latest passage flow rate measurement process is smaller than a predetermined value, it is determined that there is no abnormality in the flow rate, and the process is terminated without shutting off the gas cutoff valve 10.

  On the other hand, if the instantaneous flow rate is larger than a predetermined value, it is determined that a flow rate abnormality has occurred, and the gas shutoff valve 10 is shut off, and the process is terminated.

Even if an instantaneous flow rate greater than or equal to a predetermined value is not measured, if it takes a long time to confirm return safety, it is determined that a flow rate abnormality has occurred and the gas shut-off valve 10 is closed. The process ends.
JP 2005-189216 A

  However, the ultrasonic flow meter shown in FIG. 14 uses whether or not a measurement abnormality or a flow rate fluctuation continues for a certain time or more in determining the stop process when stopping the determination of the flow rate abnormality. Therefore, even if the measurement abnormality or flow rate fluctuation is not caused by the mixture of air, it may be erroneously determined that the air is mixed. Conversely, even if air is mixed, there is a possibility that it is erroneously determined that there is no abnormality if no continuous measurement abnormality or flow rate fluctuation is observed.

  Furthermore, a certain amount of time is required for judgment in order to see the duration of measurement abnormality and flow rate fluctuation.

  Further, regarding the return processing from the stopped state, since the return processing is performed using only the prescribed flow rate value and time as threshold values, there is a lack of reliability.

  The present invention solves the above-mentioned problems of the prior art, and an ultrasonic flowmeter that detects the mixture of air and gas in the fluid in the flow path quickly and accurately and does not cause erroneous determination of device abnormality or flow abnormality. It is an issue to provide.

  In order to solve the above problems, an ultrasonic flowmeter according to the present invention is a pair of the invention according to claim 1 that is installed at a certain distance from the upstream side and the downstream side of the flow path through which the fluid to be measured flows. An ultrasonic transducer, a time measuring unit for measuring a propagation time of an ultrasonic signal transmitted and received between the pair of ultrasonic transducers, and the object to be measured based on the propagation time measured by the time measuring unit. An ultrasonic flowmeter having a flow rate measuring means for measuring the flow rate of the fluid to be measured, the temperature measuring means for measuring the temperature in the flow path, and the fluid in the case where no mixture exists in the fluid to be measured Storage means for preliminarily storing propagation time data corresponding to the temperature; propagation time data stored by the storage means corresponding to the temperature measured by the temperature measurement means; and the propagation time measured by the time measurement means. And based It can the characterized in that it comprises a mixed detection means for detecting whether or not mixed into the fluid to be measured occurs.

  According to a second aspect of the present invention, there is provided a pair of ultrasonic transducers installed at a fixed distance on the upstream side and the downstream side of the flow path through which the fluid to be measured flows, and transmission / reception between the pair of ultrasonic transducers. An ultrasonic flowmeter having time measuring means for measuring a propagation time of the ultrasonic signal to be measured and flow rate measuring means for measuring the flow rate of the fluid to be measured based on the propagation time measured by the time measuring means. A temperature measuring means for measuring the temperature in the flow path; a storage means for preliminarily storing sound speed data corresponding to the temperature of the fluid when the fluid to be measured is not mixed; and the temperature measuring means Whether or not the fluid to be measured is mixed based on the sound speed data stored by the storage means corresponding to the temperature measured by the sound speed based on the sound speed based on the propagation time measured by the time measuring means. detection Characterized in that it comprises a mixed detection means that.

  According to a third aspect of the present invention, there is provided the first warning means according to the first or second aspect, further comprising a first warning means for giving a warning when occurrence of mixing is detected by the mixing detection means.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the voltage measuring unit measures the voltage level of the received signal of the ultrasonic signal transmitted and received between the pair of ultrasonic transducers. An abnormality detection unit that detects at least one of a device abnormality and a flow rate abnormality based on the voltage measurement unit and the flow rate measurement unit, and an abnormality when a device abnormality or a flow rate abnormality is detected by the abnormality detection unit. A second warning means for giving a warning according to the situation; and a stopping means for closing the shut-off valve and stopping the fluid to be measured when a device abnormality or a flow rate abnormality is detected by the abnormality detection means, and the abnormality The detection means detects at least one of an abnormality in the device and an abnormality in the flow rate only when no mixture is detected by the mixture detection means.

  According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the apparatus further comprises a return unit that opens the shut-off valve from the state in which the fluid to be measured is stopped by the stop unit and returns the flow rate measurement.

  A sixth aspect of the present invention includes the pressure detection means for detecting pressure according to any one of the first to fifth aspects, wherein the mixed detection means further includes pressure data detected by the pressure detection means. Based on this, it is detected whether or not mixing occurs in the fluid to be measured.

  A seventh aspect of the present invention includes, in any one of the first to sixth aspects, further comprising an odor detection means for detecting an odor, and the mixture detection means is further detected by the odor detection means. It is characterized in that it is detected whether or not mixing is occurring in the fluid to be measured based on odor data.

  The invention according to claim 8 is provided with the vibration detection means for detecting vibration in any one of claims 1 to 7, wherein the mixed detection means further includes the vibration data detected by the vibration detection means. Based on this, it is detected whether or not mixing occurs in the fluid to be measured.

  A ninth aspect of the present invention is the method according to any one of the first to eighth aspects, further comprising density detection means for detecting a density, wherein the mixed detection means further includes density data detected by the density detection means. Based on this, it is detected whether or not mixing occurs in the fluid to be measured.

  The invention according to a tenth aspect is the storage medium according to any one of the fourth to ninth aspects, wherein the storage unit further includes propagation time data and a temperature corresponding to a temperature when the flow path is filled with air. At least one of the corresponding sound speed data and the voltage level data of the reception signal of the ultrasonic signal is stored in advance, and the abnormality detection unit is stored in the storage unit even when the fluid to be measured is only air. It is characterized in that at least one of a device abnormality and a flow rate abnormality is detected based on the obtained data.

  An eleventh aspect of the present invention is that, in any one of the fourth to tenth aspects, the storage unit further includes propagation time data corresponding to a temperature when gas and air are mixed in the flow path. When at least one of sound velocity data corresponding to temperature and voltage level data of the reception signal of the ultrasonic signal is stored in advance, the abnormality detecting unit is configured when the fluid to be measured is a mixture of gas and air. Is also characterized in that at least one of an abnormality in the device and an abnormality in the flow rate is detected based on the data stored in the storage means.

  The invention according to claim 12 is the invention according to any one of claims 4 to 11, wherein the abnormality detecting means has an amplitude of voltage level data measured by the voltage measuring means smaller than a first specified value, Then, when it becomes larger than the 2nd specified value which is a value larger than a 1st specified value, it transfers to the mode which measures flow volume, It is characterized by the above-mentioned.

  A thirteenth aspect of the invention is characterized in that, in any one of the fifth to twelfth aspects, the return means returns the flow rate measurement by an external operation.

  A fourteenth aspect of the present invention is the method according to any one of the fifth to thirteenth aspects, wherein the abnormality detecting unit continues or continues every time a specified time has elapsed after the fluid to be measured is stopped by the stopping unit. The abnormality detection is performed, and the return means returns the flow rate measurement when no abnormality is detected by the abnormality detection means.

  A fifteenth aspect of the present invention is the electronic device according to any one of the fifth to fourteenth aspects, wherein the return means includes at least one of the pressure detection means, the odor detection means, the vibration detection means, and the concentration detection means. The flow rate measurement is restored when no abnormality is detected based on one means.

  According to the first aspect of the present invention, it is possible to detect whether or not the fluid to be measured is mixed based on the propagation time of the ultrasonic signal. Since it is only compared with the propagation time data stored in advance in the storage means, it is possible to detect the presence or absence of mixing quickly and accurately. Further, since the detection is performed based on the temperature measured by the temperature measuring means, it is possible to accurately detect the mixture corresponding to the propagation time that varies depending on the temperature.

  According to invention of Claim 2 of this invention, it can be detected whether mixing has generate | occur | produced in the to-be-measured fluid based on the speed of sound of an ultrasonic signal. Since the sound speed is used as a basis instead of the propagation time, the detection can be performed accurately without being influenced by the flow velocity factor. Thereafter, the same effect as in the case of claim 1 can be obtained.

  According to the invention described in claim 3 of the present invention, a warning is given when mixing is detected by the mixing detection means, so that it is possible to quickly cope with mixing.

  According to the invention described in claim 4 of the present invention, the apparatus abnormality or the flow rate abnormality is detected by the abnormality detecting means and the warning means is warned, so that these abnormalities can be dealt with quickly. In addition, when an abnormality is detected by the abnormality detection means, the stopping means stops the fluid to be measured, so gas can be prevented from flowing in and out in a measurement abnormal state, and dangers such as gas leaks can be avoided. can do.

  Furthermore, since abnormality detection is performed by the abnormality detection means only when no mixture is detected by the mixture detection means, it is possible to avoid misjudging a simple air mixture state as an equipment abnormality or a flow rate abnormality.

  According to the fifth aspect of the present invention, after the fluid to be measured is stopped by the stop unit, the flow rate can be measured again by opening the shut-off valve by the return unit.

  According to the sixth aspect of the present invention, by using the pressure detected by the pressure detection means for the determination of the mixture detection, the mixture can be detected more accurately.

  According to the seventh aspect of the present invention, the mixture can be detected more accurately by using the odor detected by the odor detection means for the determination of the mixture detection.

  According to the eighth aspect of the present invention, it is possible to detect the mixture more accurately by using the vibration detected by the vibration detecting means for the determination of the mixture detection.

  According to the ninth aspect of the present invention, it is possible to detect the mixture more accurately by using the concentration detected by the concentration detection unit for the determination of the mixture detection.

  According to the invention described in claim 10 of the present invention, by determining the criteria for judging the abnormality of the device using only air, the device detecting the abnormality of the device can be accurately detected even when the flow path is filled with only the air. be able to. For this reason, it is possible to determine an apparatus abnormality even in a state before installation.

  According to the eleventh aspect of the present invention, by determining the criteria for judging device abnormality according to the concentration, even when gas and air are mixed in the flow path, the device abnormality can be accurately detected by the abnormality detecting means. Can be detected. Therefore, it is possible to provide an ultrasonic flowmeter that does not cause an erroneous determination of an abnormality of the ultrasonic flowmeter even when air is mixed even after the work of filling the flow path with gas.

  According to the invention of claim 12 of the present invention, the voltage level measured by the voltage measuring means becomes smaller than the first specified value, and thereafter becomes larger than the second specified value which is a value larger than the first specified value. Since the flow rate is measured only when there is a mixture of air and gas, the anomaly detection means does not detect equipment anomalies, and can detect gas fullness and gas fullness. Only when the flow measurement can be started automatically.

  According to the thirteenth aspect of the present invention, after the fluid to be measured is stopped by the stopping means, the measurement of the flow rate is returned by an external operation. Therefore, the flow rate measurement can be returned only when safety is confirmed. it can.

  According to the fourteenth aspect of the present invention, after the fluid to be measured is stopped by the stopping means, the flow rate measurement is returned only when no abnormality is detected by the abnormality detecting means. Only flow measurement can be restored.

  According to the fifteenth aspect of the present invention, the flow rate measurement is restored only when no abnormality is detected based on at least one of the pressure detection means, the odor detection means, the vibration detection means, and the concentration detection means. The flow measurement can be returned after the safety check is performed more reliably.

  Hereinafter, embodiments of the ultrasonic flowmeter of the present invention will be described in detail with reference to the drawings.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of the first embodiment of the present invention, and FIG. 2 is a diagram showing details of the control unit of FIG.

  First, the configuration of the present embodiment will be described. As shown in FIG. 1, the ultrasonic flowmeter according to the present embodiment includes a gas inlet 100a, a gas flow path 100c, a gas outlet 100b, and an ultrasonic transducer. 110 a, ultrasonic transducer 110 b, storage unit 120, shut-off valve 130, display unit 140, temperature sensor 160, and control unit 200.

  The ultrasonic transducer 110a and the ultrasonic transducer 110b are installed at a certain distance from the upstream side and the downstream side of the gas flow channel 100c through which the fluid to be measured flows. Between the ultrasonic transducer 110a and the ultrasonic transducer 110b, the operation of transmitting and receiving ultrasonic waves to and from each other in the forward direction and the reverse direction of the fluid flow is repeatedly performed, and the difference in ultrasonic propagation integration time in each direction is performed. Based on the above, the flow rate is calculated.

  The storage unit 120 corresponds to the storage unit of the present invention and is connected to the control unit 200.

  The temperature sensor 160 corresponds to the temperature measurement means of the present invention, is connected to the control unit 200, detects the temperature of the gas in the gas flow path 100c, and sends it to the control unit 200 as temperature data.

  The control unit 200 measures the flow rate based on the propagation time obtained based on the ultrasonic signals transmitted and received from the ultrasonic transducers 110a and 110b. Further, the control unit 200 monitors the measured flow rate data, and when it is determined that an abnormality has occurred based on the flow rate data, the control unit 200 sends a control signal to the shutoff valve 130 to close the gas flow path 100c and shut off the gas. To do.

  The display unit 140 is an LED, an LCD, or the like, and normally displays a gas use integrated value in response to a control signal from the control unit 200, and when an abnormality such as gas leakage occurs, a message indicating that fact Is displayed.

  Next, the internal configuration of the control unit 200 will be described. As shown in FIG. 2, the control unit 200 includes a propagation time measurement unit 210, a flow rate measurement unit 220, a mixture detection unit 230, a first warning unit 240, a voltage measurement unit 250, an abnormality detection unit 260, a second warning unit 270, The stop unit 280 is configured.

  The propagation time measurement unit 210 corresponds to the time measurement unit of the present invention, and is connected to the ultrasonic transducers 110a and 110b, the flow rate measurement unit 220, and the mixed detection unit 230.

  The flow rate measurement unit 230 corresponds to the flow rate measurement unit of the present invention, and is connected to the propagation time measurement unit 210, the abnormality detection unit 260, and the display unit 140. The flow rate measuring unit 230 measures the flow rate of the fluid to be measured based on the propagation time measured by the propagation time measuring unit 210.

  The mixed detection unit 230 corresponds to the mixed detection unit of the present invention, and is connected to the storage unit 120, the temperature sensor 160, the propagation time measurement unit 210, the first warning unit 240, and the abnormality detection unit 260, respectively.

  The first warning unit 240 corresponds to the first warning unit of the present invention, and is connected to the mixed detection unit 230.

  The voltage measurement unit 250 corresponds to the voltage measurement unit of the present invention, and is connected to the ultrasonic transducers 110 a and 110 b and the abnormality detection unit 260.

  The abnormality detection unit 260 corresponds to the abnormality detection unit of the present invention, and is connected to the storage unit 120, the flow rate measurement unit 220, the mixed detection unit 230, the voltage measurement unit 250, the second warning unit 270, and the stop unit 280.

  The second warning unit 270 corresponds to the second warning unit of the present invention, and is connected to the abnormality detection unit 260 and the display unit 140. The stop unit 280 corresponds to the stop unit of the present invention, and is connected to the abnormality detection unit 260 and the shutoff valve 130.

  FIG. 3 is a flowchart showing the device abnormality determination process. The operation of the ultrasonic flowmeter according to the first embodiment will be described with reference to FIG. Here, the memory | storage part 120 hold | maintains the propagation time data or sound speed data for every temperature in the gas in case mixing does not occur beforehand. Note that the data stored in the storage unit 120 is not limited to the supplied gas, and may be data of the gas that is the main component. The sound speed data is not limited to the sound speed data to be held, such as an expression for deriving the sound speed based on the specific heat ratio, gas constant, and temperature, and an expression for deriving the sound speed based on the atmospheric pressure and density.

  First, an air mixing determination process is performed (S101). The propagation time measurement unit 210 measures the propagation time of the ultrasonic signal transmitted / received between the ultrasonic transducers 110 a and 110 b and transmits the measurement result to the mixed detection unit 230. At this time, not the propagation time but the measurement result of the sound speed obtained from the propagation time may be used. Assuming that the speed of sound is c, the flow velocity of gas flow is v, and the distance from the ultrasonic transducer 110a to the ultrasonic transducer 110b is L, the ultrasonic signal from the ultrasonic transducer 110a to the ultrasonic transducer 110b is The propagation time is L / (c + v), and the propagation time of the ultrasonic signal from the ultrasonic transducer 110b to the ultrasonic transducer 110a is L / (c−v). If the value of L is known, the speed of sound can be obtained based on these propagation times.

  Further, the temperature sensor 160 measures the temperature in the gas flow path 100 c and transmits the measurement result to the mixed detection unit 230.

  The mixture detection unit 230 detects the mixture of air in the gas flow path 100 c, and the measurement result of the propagation time or the speed of sound transmitted by the propagation time measurement unit 210 and the measurement of the temperature transmitted by the temperature sensor 160. The propagation time data or sound speed data held in the storage unit 120 corresponding to the result is compared, and it is detected whether or not air is mixed in the fluid to be measured in the gas flow path 100c. In the comparison, for example, when the measured propagation time or sound speed takes more time than the propagation time of the corresponding temperature held in the storage unit 120, or when the sound speed of the corresponding temperature is less than that, the air flows into the flow path 100c. Is determined to be mixed.

  For example, when comparing methane, which is a main component of city gas, with air, the sound velocity at 0 ° C. and 1 atm is about 430 m / s in methane and about 331 m / s in dry air. Accordingly, the speed of sound is slower when air is mixed with the gas flow path 100c than when the gas flow path 100c is filled only with gas.

The sound speed c can be expressed by the following equation.

Here, k is a specific heat ratio, p is atmospheric pressure, and ρ is density. Methane and air (dry) differ greatly in density. For example 0 ° C., density at 1atm is methane 0.72 kg / m ^3, since the air is 1.29 kg / m ^3, the difference comes to the value of the sound velocity c, as described above.

  When the mixture detection unit 230 detects the presence of air in the flow path 100c, the first warning unit 240 issues a warning (S103). The warning by the first warning unit 240 may be any type, and a warning may be displayed by displaying a message on the display unit 140 or a warning by sound or light. After the warning, the process returns to the mixture detection process (S101) again.

  When the mixture detection unit 230 does not detect the presence of air in the flow path 100c, the abnormality detection unit 260 detects at least one of an abnormality in the device and an abnormality in the flow rate (S105). Here, the storage unit 120 holds in advance at least one of voltage level data and flow rate data of a reception signal in the reference gas.

  When obtaining a device abnormality, the voltage measurement unit 250 measures the voltage level of the reception signal of the ultrasonic signal in the ultrasonic transducer 110 a or the ultrasonic transducer 110 b and transmits the measurement result to the abnormality detection unit 260. The abnormality detection unit 260 compares the transmitted voltage level measurement result with the voltage level data stored in the storage unit 120 to detect the presence or absence of an abnormality.

  When obtaining an abnormal flow rate, the propagation time measurement unit 210 measures the propagation time of the ultrasonic signals transmitted and received by the ultrasonic transducers 110 a and 110 b and transmits the measurement result to the flow rate measurement unit 220. The flow rate measurement unit 220 obtains the gas flow rate based on the propagation time measured by the propagation time measurement unit 210, and obtains the instantaneous flow rate by multiplying the obtained gas flow rate by the cross-sectional area of the gas flow path 100c. The flow rate measurement unit 220 further transmits the obtained flow rate measurement result to the abnormality detection unit 260. The abnormality detection unit 260 compares the transmitted flow rate measurement result with the flow rate data stored in the storage unit 120 to detect the presence or absence of an abnormality. If there is no abnormality, the process returns to the mixed detection process (S101) again.

  If an abnormality or flow rate abnormality is detected by the abnormality detection unit 260, the second warning unit 270 issues a warning, and the stop unit 280 closes the shut-off valve 130 to stop the inflow / outflow of gas as the fluid to be measured (S107). ).

  The warning by the second warning unit 270 may be any type, and a warning may be displayed by displaying a message on the display unit 140 or a warning by sound or light. Further, warnings may be given in stages according to the degree of abnormality. For example, a message may be displayed on the display unit 140 if the degree of abnormality is mild, an alarm is sounded if the level is moderate, and the shutoff valve 130 is closed via the stop unit 280 for the first time when the degree of severity is severe.

  As described above, according to the ultrasonic flowmeter according to the first embodiment of the present invention, it is possible to detect whether or not the fluid to be measured is mixed based on the propagation time or speed of sound of the ultrasonic signal. it can. When detecting the presence / absence of mixing based on the propagation time, since it is only compared with the propagation time data stored in advance in the storage unit 120, it is possible to detect the presence / absence of mixing quickly and accurately. Further, since the detection is performed based on the temperature measured by the temperature sensor 160, the detection of the mixture can be made accurate in response to the propagation time that varies depending on the temperature.

  When detecting the presence / absence of mixing based on the sound velocity, the detection can be accurately performed without being influenced by the element of the flow velocity because it is based on the sound velocity instead of the propagation time.

  Further, when the mixture is detected by the mixture detection unit 230, the first warning unit 240 gives a warning, so that it is possible to quickly cope with the mixture.

  In addition, since the abnormality detection unit 260 detects the device abnormality or the flow rate abnormality and the second warning unit 270 warns, it is possible to quickly cope with these abnormalities. In addition, when an abnormality is detected by the abnormality detection unit 260, the stop unit 280 stops the fluid to be measured, so that the inflow and outflow of gas in the state of measurement abnormality can be prevented, and there is a risk of gas leakage and the like. Can be avoided.

  Furthermore, since the abnormality detection unit 260 detects the abnormality only when the mixture detection unit 230 does not detect the mixture, it is possible to avoid erroneously determining a simple air mixture state as a device abnormality or a flow rate abnormality.

  Next, FIG. 4 is a block diagram of Embodiment 2 of the present invention. The difference from the configuration of the first embodiment is that a vibration sensor 150, an odor sensor 170, a pressure sensor 180, and a concentration sensor 190 are newly provided. The vibration sensor 150 corresponds to the vibration detecting means of the present invention and detects the vibration of the ultrasonic flowmeter. The odor sensor 170 corresponds to the odor detection means of the present invention and detects the odor in the gas flow channel 100c. The pressure sensor 180 corresponds to the pressure detection means of the present invention and detects the pressure in the gas flow path 100c. The concentration sensor 190 corresponds to the concentration detecting means of the present invention, and detects the concentration of the gas in the gas flow path 100c. These sensors are connected to the control unit 200 and further connected to the mixed detection unit 230 inside the control unit 200.

  Next, the operation of the ultrasonic flowmeter according to the embodiment 2 will be described. The basic operation is the same as that in the flowchart showing the device abnormality determination process in FIG. 3 described in the first embodiment. However, in the air mixing determination process (S101), the mixing determination is performed with reference to information from each sensor.

  The mixture determination process using each sensor will be specifically described. FIG. 5 is a diagram showing the relationship between measured values and specified values of pressure, odor level, vibration, and concentration. The memory | storage part 120 hold | maintains the predetermined value about each of a pressure, an odor degree, a vibration, and a density | concentration beforehand.

  FIG. 5A shows the pressure value measured by the pressure sensor 180 on the time axis. In FIG. 5A, two specified values are set as specified value A and specified value B, but the specified value may be one. When there is one specified value, the mixture detection unit 230 compares the pressure data in the gas flow path 100c measured by the pressure sensor 180 with the specified value set in the storage unit 120, and is equal to or less than the specified value. In the case of the pressure, it is determined that no gas is supplied.

  When two specified values are set, an upper limit value A1 and a lower limit value B1 are set to the specified values as shown in FIG. 5A, and the measured pressure data is within the specified values A1 and B1. It is also possible to detect mixing depending on whether or not.

  As described above, the mixture detection unit 230 further detects whether or not the measurement target fluid is mixed based on the pressure data detected by the pressure sensor 180.

  FIG. 5B shows the odor value measured by the odor sensor 170 on the time axis. As in the case of the pressure in FIG. 5A, when there is one specified value, the mixture detection unit 230 stores the odor data in the gas flow path 100 c measured by the odor sensor 170 and the storage unit 120. Comparison is made with the specified value set to, and if the odor is below the specified value, it is determined that no gas is supplied.

  When two specified values are set, an upper limit value A2 and a lower limit value B2 are set to the specified values as shown in FIG. 5B, and the measured odor data is within the specified values A2 and B2. It is also possible to detect mixing depending on whether or not.

  As described above, the mixture detection unit 230 further detects whether or not the measurement target fluid is mixed based on the odor data detected by the odor sensor 170.

  FIG. 5C shows the value of vibration measured by the vibration sensor 150 on the time axis. As in the case of pressure and odor, when the specified value is one, the mixed detection unit 230 sets the vibration data of the ultrasonic flowmeter measured by the vibration sensor 150 and the setting set in the storage unit 120. When the vibration exceeds the specified value, it is determined that the gas is not supplied before the flow meter is installed, and it is determined that air is mixed. In addition, the mixture detection unit 230 is set not to perform mixture detection based on vibration data after the flow meter is installed. By doing so, it is possible to prevent misjudgment due to vibration such as an earthquake after the installation of the ultrasonic flowmeter.

  Furthermore, as shown in FIG. 5 (c), it is possible to set two specified values and detect the mixture depending on whether or not the measured vibration data is within the range of the specified values A3 and B3. Thereby, it is possible to allow a certain amount of vibration even in an installation place where slight vibration continues.

  As described above, the mixture detection unit 230 further detects whether or not mixing occurs in the fluid to be measured based on the vibration data detected by the vibration sensor 150.

  FIG. 5D shows the density value measured by the density sensor 190 on the time axis. As in the case of pressure, odor, and vibration, when there is one specified value, the mixed detection unit 230 sets the concentration data in the gas flow path 100 c measured by the concentration sensor 190 and the storage unit 120. If the concentration is less than the specified value, it is determined that the gas is not supplied before the flow meter is installed, and it is determined that air is mixed.

  When two specified values are set, an upper limit value A4 and a lower limit value B4 are set to the specified values as shown in FIG. 5D, and the measured density data is within the specified values A4 and B4. It is also possible to detect mixing depending on whether or not.

  As described above, the mixture detection unit 230 further detects whether or not mixing occurs in the fluid to be measured based on the concentration data detected by the concentration sensor 190.

  As described above, according to the ultrasonic flowmeter according to the second embodiment of the present invention, it is possible to detect the mixture more accurately by providing the sensors.

  In addition, by not determining the device abnormality before installing the ultrasonic flow meter, it is possible to provide an ultrasonic flow meter that does not cause an erroneous determination of the device abnormality.

  Next, an ultrasonic flowmeter according to Example 3 of the present invention will be described. The configuration of this embodiment is the same as the configuration of Example 1 or Example 2.

  FIG. 6 is a flowchart in which a device abnormality determination using only air is added. The operation of the ultrasonic flowmeter according to the third embodiment will be described with reference to FIG. 3 is different from the flowchart of FIG. 3 in that when the fluid in the gas flow path 100c is only air, the device abnormality determination is performed.

  First, the air mixing determination process (S101) is the same as the flowchart of FIG. Here, the storage unit 120 holds in advance a reference value for each sensor that can detect whether the temperature is propagation time data or sound speed data for each temperature in the air or only air. When air mixing is detected in the air mixing determination process (S101), the mixing detecting unit 230 detects whether or not the fluid in the gas flow path 100c is only air based on the data in the storage unit 120. (S102). When the mixing detection unit 230 detects not only air but also gas mixing in the fluid in the gas flow path 100c, the first warning unit 240 issues a warning (S103), and the process returns to the air mixing determination process (S101).

  When the mixed detection unit 230 determines that the fluid in the gas flow path 100c is only air, the first warning unit 240 issues a warning (S104), and the abnormality detection unit 260 performs device abnormality determination (S105). . Here, a difference may be given between the warning (S103) by the first warning unit 240 when the mixture is detected and the warning (S104) by the first warning unit 240 when only air is detected. For example, it is possible to display the fact on the display unit 140, or to give a difference to the warning by sound or light.

  The storage unit 120 stores in advance at least one of the propagation time data corresponding to the temperature, the sound speed data corresponding to the temperature, and the voltage level data of the reception signal of the ultrasonic signal when the gas flow path 100c is filled with air. Hold. These data serve as abnormal equipment determination criteria configured based on the speed of sound in the air and the voltage level of the received signals of the ultrasonic signals of the ultrasonic transducers 110a and 110b.

  The abnormality detection unit 260 includes the voltage level of the reception signal of the ultrasonic signal measured by the voltage measurement unit 250, the flow rate data measured by the flow rate measurement unit 220, and the data that is the abnormal device determination standard held in the storage unit 120. Based on the above, at least one of a device abnormality and a flow abnormality is detected. In this way, the device abnormality determination (S105) can be performed even when the fluid in the gas flow path 100c is air.

  As described above, according to the ultrasonic flowmeter according to the form of the third embodiment of the present invention, even when the gas flow path 100c is filled with only air by determining the criteria for judging the abnormality of only the air, The abnormality detection unit 260 can accurately detect a device abnormality. For this reason, it is possible to determine an apparatus abnormality even in a state before installation.

  Next, an ultrasonic flowmeter according to Example 4 of the present invention will be described. The configuration of the present embodiment is the same as that of the second embodiment, and at least the density sensor 190 is provided.

  FIG. 7 is a flowchart in which device abnormality determination is performed in a state where gas and air are mixed. Further, FIG. 8 is a diagram showing a determination specified value for determining abnormality and how to determine it. The operation of the ultrasonic flowmeter according to the fourth embodiment will be described with reference to FIGS. 7 is different from the flowchart of FIG. 3 in that, when the fluid in the gas flow path 100c is a mixture of gas and air, the device abnormality is determined after warning.

  First, the mixing detection unit 230 performs the air mixing determination process (S101), and the first warning unit 240 issues a warning (S103a) when air is mixed as in the flowchart of FIG. After the warning, the abnormality detection unit 260 performs device abnormality detection (S105). Here, the storage unit 120 stores the propagation time data corresponding to the temperature, the sound speed data corresponding to the temperature, and the voltage level data of the reception signal of the ultrasonic signal when gas and air are mixed in the gas flow path 100c in advance. Hold at least one. These data serve as abnormal equipment judgment criteria configured based on the speed of sound in the air and the voltage level of the received signal of the ultrasonic signal transmitted and received by the ultrasonic transducers 110a and 110b.

  The abnormality detection unit 260 includes the voltage level of the reception signal of the ultrasonic signal measured by the voltage measurement unit 250, the flow rate data measured by the flow rate measurement unit 220, and the data that is the abnormal device determination standard held in the storage unit 120. Based on the above, at least one of a device abnormality and a flow abnormality is detected. In this way, the device abnormality determination (S105) can be performed even when the fluid in the gas flow path 100c is a mixture of gas and air.

  As shown in FIG. 8, the specified value, which is an abnormal equipment determination criterion stored in the storage unit 120, is determined at a constant interval according to the concentration. The concentration of the fluid in the gas flow channel 100c may be measured in any way, for example, there is a method using a concentration sensor 190. At this time, the concentration sensor 190 measures the concentration of the fluid in the gas flow path 100c. Therefore, the abnormality detection unit 260 can make a determination based on the density data measured by the density sensor 190. It is also possible to measure the concentration by detecting sound velocity data or flow velocity data based on the propagation time of ultrasonic signals transmitted and received by the ultrasonic transducers 110a and 110b.

  As described above, according to the ultrasonic flowmeter according to the embodiment 4 of the present invention, since the determination criterion for the device abnormality according to the concentration is determined, the fluid in the gas flow path 100c is only gas or only air. The abnormality detection unit 260 can accurately detect the device abnormality or the flow rate abnormality not only in the case but also in the case of being mixed. That is, it is possible to provide an ultrasonic flowmeter that does not cause an erroneous determination of an abnormality in the ultrasonic flowmeter even when air is mixed even after the gas flow path 100c is filled with gas.

  Next, an ultrasonic flowmeter according to Example 5 of the present invention will be described. The configuration of this embodiment is the same as the configuration of Example 1 or Example 2.

  FIG. 9 is a flowchart in which processing for shifting to the measurement mode is added based on the amplitude of the received signal. FIG. 10 is a diagram showing an example of the voltage level data of the reception signal of the ultrasonic signal, and FIG. 11 is a diagram showing how to define the prescribed value of the amplitude of the voltage level of the reception signal. The operation of the ultrasonic flowmeter according to the fifth embodiment will be described with reference to FIGS. 9, 10, and 11.

  In FIG. 9, first, a determination process is performed to determine whether or not the gas flow path 100c is filled with gas (S201). The reception waveform of the ultrasonic signal in the ultrasonic transducer 110a or 110b is as shown in FIG. The voltage measurement unit 250 measures the voltage level data of the nth wave (n is preset) of the received signal, and the abnormality detection unit 260 fills the gas based on the voltage level data measured by the voltage measurement unit 250. Is detected.

  When the voltage level data of the reception signal of the ultrasonic signal in the ultrasonic transducer 110a or 110b is measured in a state where air and gas are mixed in the gas flow path 100c, the voltage level measured as compared with the case of only air. The amplitude of the data is reduced. Further, the amplitude of the voltage level data of the reception signal of the ultrasonic signal in the ultrasonic transducer 110a or 110b in a state where the gas flow path 100c is filled with gas becomes larger than that in the mixed state of air and gas.

  FIG. 11 shows only the amplitude of the nth wave measured and graphed on the time axis. In FIG. 11, the inside of the gas flow path 100c is initially filled with air, and then gas is gradually injected and finally filled with gas. The amplitude of the n-th wave once becomes small when the gas is injected, and has a large amplitude when the gas flow path 100c is filled with the gas.

  Therefore, it is possible to detect gas fullness by determining a prescribed value as shown in FIG. Specifically, a first specified value A is determined to detect a mixed state of air and gas, and a second specified value B, which is a value larger than the first specified value, is further determined to detect gas fullness. In the abnormality detection unit 260, the amplitude of the voltage level data measured by the voltage measurement unit 250 becomes smaller than the first specified value A, and then becomes larger than the second specified value B which is a value larger than the first specified value. In this case, it is determined that the gas is full, and the flow shifts to a mode for measuring the flow rate (S203).

  The subsequent operation is the same as that of the fourth embodiment described with reference to FIG.

  As described above, according to the ultrasonic flowmeter according to the form of the fifth embodiment of the present invention, the voltage level measured by the voltage measuring unit 250 is smaller than the first specified value, and then larger than the first specified value. Since the flow rate is measured only when the value exceeds the second specified value which is a value, the abnormality detection unit 260 does not detect the device abnormality and detects the gas fullness when air and gas are mixed. In addition, the flow rate measurement can be automatically started only when gas fullness is detected.

  Next, FIG. 12 is a block diagram of the control unit 200 in Embodiment 6 of the present invention. The difference from the configuration of the first embodiment is that a return unit 290 is newly provided. The return unit 290 corresponds to the return means of the present invention, and opens the shutoff valve 130 from the state where the fluid to be measured is stopped by the stop unit 280 to return the flow rate measurement. Therefore, the return unit 290 is connected to the stop unit 280, the abnormality detection unit 260, and the shutoff valve 130.

  Next, the operation of the ultrasonic flowmeter according to the embodiment 6 will be described. FIG. 13 is a flowchart with the return process added. When the abnormality detection unit 260 finds a device abnormality in the ultrasonic flowmeter by the device abnormality determination process (S209), the stop unit 280 closes the shutoff valve 130 to shut off the gas, and performs a warning / stop process (S211). Up to this point, the operation is the same as that of the fifth embodiment described with reference to FIG.

  Thereafter, the return unit 290 performs a return process (S213). When it is confirmed that the return process is safe, the flow measurement is returned.

  There are several ways to confirm safety. For example, the return unit 290 recovers from the stopped state by operating a button installed outside the ultrasonic flowmeter, and restarts the flow measurement. In this case, the apparatus abnormality determination process (S215) by the abnormality detection unit 260 is not performed, and the measurement mode transition (S203) is performed.

  In addition, the abnormality detection unit 260 can perform device abnormality determination (S215) every specified time, and can return the flow rate measurement if no abnormality is found.

  In addition, even after the fluid to be measured is stopped by the stop unit 280, the abnormality detection unit 260 continues to execute the device abnormality determination process (S215), and returns the flow measurement if no device abnormality is found (S203). Is also possible.

  Furthermore, the abnormality detection unit 260 performs device abnormality determination processing (S215) based on information from various sensors, and uses it as at least one of the vibration sensor 150, the odor sensor 170, the pressure sensor 180, and the concentration sensor 190. On the basis of this, it is also possible to return the flow rate measurement when no abnormality is detected (S203).

  If an abnormality is detected by the device abnormality determination process (S215), the process returns to the warning / stop process (S211) again.

  As described above, according to the ultrasonic flowmeter according to the sixth embodiment of the present invention, after the stop unit 280 stops the fluid to be measured, the return unit 290 opens the shut-off valve, so the flow rate is measured again. be able to.

  In addition, after the stop unit 280 stops the fluid to be measured, the measurement of the flow rate can be returned by an external operation. Therefore, the flow rate measurement can be returned only when safety is confirmed.

  In addition, after the stop unit 280 stops the fluid to be measured, the flow rate measurement can be returned only when the abnormality detection unit 260 does not detect the abnormality. Therefore, the flow rate measurement is returned only when safety is confirmed. be able to.

  Furthermore, since the flow rate measurement is restored only when no abnormality is detected based on at least one of the vibration sensor 150, the odor sensor 170, the pressure sensor 180, and the concentration sensor 190, the flow rate measurement is performed after confirming safety more reliably. Can be restored.

  The ultrasonic flow meter according to the present invention can be used for an ultrasonic flow meter such as an ultrasonic gas meter capable of measuring a gas flow rate.

It is a block diagram of the ultrasonic flowmeter of the form of Example 1 of the present invention. It is a block diagram which shows the internal structure of the control part of Example 1 of this invention. It is a flowchart figure which shows the apparatus abnormality determination process of Example 1 of this invention. It is a block diagram of the ultrasonic flowmeter of the form of Example 2 of the present invention. It is a figure which shows the relationship between the measured value of a pressure, the odor degree, a vibration, and a density | concentration in Example 2 of this invention, and a defined value. It is a flowchart figure which shows the operation | movement of the form of Example 3 of this invention. It is a flowchart figure which shows the operation | movement of the form of Example 4 of this invention. It is a figure which shows the judgment specified value of the abnormality judgment in Example 4 of this invention, and how to determine it. It is a flowchart figure which shows the operation | movement of the form of Example 5 of this invention. It is a figure which shows one example of the voltage level data of the received signal of the ultrasonic signal of Example 5 of this invention. It is a figure which shows how to define the regulation value of the amplitude of the voltage level of the received signal of Example 5 of this invention. It is a block diagram which shows the internal structure of the control part of Example 6 of this invention. It is a flowchart figure which shows the operation | movement of the form of Example 6 of this invention. It is a block diagram which shows the structure of the conventional ultrasonic flowmeter.

Explanation of symbols

TD1 transducer (flow velocity measuring means)
TD2 transducer (flow velocity measuring means)
10 Gas shut-off valve 11a Transducer I / F circuit (flow velocity measuring means)
11b Transducer I / F circuit (flow velocity measuring means)
12 Transmission circuit (transmission means, flow velocity measurement means)
13 Receiving circuit (receiving means, flow velocity measuring means)
14 μCOM
DESCRIPTION OF SYMBOLS 15 Indicator 100a Gas inflow port 100b Gas outflow port 100c Gas flow path 110a Ultrasonic vibrator 110b Ultrasonic vibrator 120 Storage part 130 Shut-off valve 140 Display part 150 Vibration sensor 160 Temperature sensor 170 Odor sensor 180 Pressure sensor 190 Concentration sensor 200 Control Unit 210 Propagation Time Measurement Unit 220 Flow Rate Measurement Unit 230 Mixed Detection Unit 240 First Warning Unit 250 Voltage Measurement Unit 260 Abnormality Detection Unit 270 Second Warning Unit 280 Stop Unit 290 Return Unit

Claims (15)

A pair of ultrasonic transducers installed at a certain distance from the upstream side and downstream side of the flow path through which the fluid to be measured flows;
Time measuring means for measuring the propagation time of an ultrasonic signal transmitted and received between the pair of ultrasonic transducers;
An ultrasonic flowmeter having flow measurement means for measuring the flow rate of the fluid to be measured based on the propagation time measured by the time measurement means,
Temperature measuring means for measuring the temperature in the flow path;
Storage means for preliminarily storing propagation time data corresponding to the temperature of the fluid in the case where mixing is not generated in the fluid to be measured;
Whether the fluid to be measured is mixed based on the propagation time data stored by the storage unit corresponding to the temperature measured by the temperature measurement unit and the propagation time measured by the time measurement unit Mixed detection means for detecting
An ultrasonic flowmeter comprising: A pair of ultrasonic transducers installed at a certain distance from the upstream side and downstream side of the flow path through which the fluid to be measured flows;
Time measuring means for measuring the propagation time of an ultrasonic signal transmitted and received between the pair of ultrasonic transducers;
An ultrasonic flowmeter having flow measurement means for measuring the flow rate of the fluid to be measured based on the propagation time measured by the time measurement means,
Temperature measuring means for measuring the temperature in the flow path;
Storage means for preliminarily storing sound velocity data corresponding to the temperature of the fluid in the case where mixing is not generated in the fluid to be measured;
Mixing occurs in the fluid to be measured based on the sound speed data stored by the storage means corresponding to the temperature measured by the temperature measuring means and the sound speed based on the propagation time measured by the time measuring means. Mixed detection means for detecting whether or not,
An ultrasonic flowmeter comprising:   The ultrasonic flowmeter according to claim 1, further comprising a first warning unit that issues a warning when occurrence of mixing is detected by the mixing detection unit. Voltage measuring means for measuring a voltage level of a reception signal of an ultrasonic signal transmitted and received between the pair of ultrasonic transducers;
An abnormality detection means for detecting at least one of an abnormality of the apparatus and an abnormality of the flow rate based on the voltage measurement means and the flow rate measurement means;
A second warning means for giving a warning according to an abnormal situation when a device abnormality or a flow abnormality is detected by the abnormality detection means;
A stop unit that closes a shut-off valve and stops the fluid to be measured when a device abnormality or a flow rate abnormality is detected by the abnormality detection unit;
4. The apparatus according to claim 1, wherein the abnormality detection unit detects at least one of a device abnormality and a flow rate abnormality only when mixing is not detected by the mixing detection unit. 5. The described ultrasonic flowmeter.   5. The ultrasonic flowmeter according to claim 4, further comprising return means for opening the shutoff valve and returning the flow measurement from a state in which the fluid to be measured is stopped by the stop means. Pressure detecting means for detecting pressure,
6. The mixture detection unit according to claim 1, wherein the mixture detection unit further detects whether or not the measurement target fluid is mixed based on pressure data detected by the pressure detection unit. 1. The ultrasonic flowmeter according to item 1. Equipped with odor detection means for detecting odor,
7. The mixture detection unit according to claim 1, further comprising detecting whether or not mixing occurs in the fluid to be measured based on the odor level data detected by the odor level detection unit. The ultrasonic flowmeter according to any one of the above. Comprising vibration detecting means for detecting vibration;
The mixed detection unit further detects whether or not the mixed fluid is generated based on vibration data detected by the vibration detection unit. 1. The ultrasonic flowmeter according to item 1. A concentration detecting means for detecting the concentration;
9. The mixture detection unit according to claim 1, wherein the mixture detection unit further detects whether or not the measurement target fluid is mixed based on the concentration data detected by the concentration detection unit. 1. The ultrasonic flowmeter according to item 1. The storage means further includes at least one of propagation time data corresponding to a temperature when the flow path is filled with air, sound speed data corresponding to the temperature, and voltage level data of a reception signal of the ultrasonic signal. Remember in advance,
5. The abnormality detection unit detects at least one of an abnormality in a device and an abnormality in a flow rate based on data stored in the storage unit even when the fluid to be measured is only air. The ultrasonic flowmeter according to any one of claims 9 to 9. The storage means further includes at least one of propagation time data corresponding to temperature, sound velocity data corresponding to temperature, and voltage level data of a reception signal of the ultrasonic signal when gas and air are mixed in the flow path. Remember one in advance,
The abnormality detecting means detects at least one of an abnormality of a device and an abnormality of a flow rate based on data stored in the storage means even when the fluid to be measured is a mixture of gas and air. The ultrasonic flowmeter according to any one of claims 4 to 10.   The abnormality detecting unit is configured such that the amplitude of the voltage level data measured by the voltage measuring unit is smaller than a first specified value and then larger than a second specified value which is a value larger than the first specified value. The ultrasonic flowmeter according to any one of claims 4 to 11, wherein the flow rate is changed to a mode for measuring a flow rate.   The ultrasonic flowmeter according to any one of claims 5 to 12, wherein the return means returns the flow rate measurement by an external operation. The abnormality detecting means performs abnormality detection every time or continuously after the measured fluid is stopped by the stopping means,
The ultrasonic flowmeter according to any one of claims 5 to 13, wherein the return means returns the flow rate measurement when no abnormality is detected by the abnormality detection means.   The return means returns flow measurement when no abnormality is detected based on at least one of the pressure detection means, the odor detection means, the vibration detection means, and the concentration detection means. The ultrasonic flowmeter according to any one of claims 5 to 14.

Images