JP6619303B2 - Gas shut-off device - Google Patents

Description

  The present invention relates to a gas shut-off device that shuts off a gas supply when it is determined that condensation has occurred in a measurement flow path that measures a gas flow rate using ultrasonic waves.

  The gas shut-off device generally includes a flow rate measuring unit that measures the gas flow rate and a shut-off unit that shuts off the gas supply. A typical example of the gas flow rate measurement method is an ultrasonic method. In the ultrasonic flow measurement means, a pair of ultrasonic transmitters / receivers are provided in the measurement flow path, and the ultrasonic propagation time is measured by switching between these transmission and reception, and the gas flow rate is calculated from the propagation time. Yes.

  When dew condensation occurs in the measurement flow path, accurate measurement of the gas flow rate is hindered, and it becomes necessary to cut off the gas supply. Therefore, conventionally, a method for determining the occurrence of condensation in the measurement channel has been proposed. For example, Patent Literature 1 discloses a flow rate measuring device that determines whether or not a gain value (amplification degree, amplification factor) has increased by a period correction determination unit during a predetermined period. The period correction determination unit detects whether or not the gain value has increased in a short period of time, thereby detecting a sudden increase in gain value due to condensation before reaching the alarm level or the cutoff level.

JP 2012-193966 A

  By the way, in the flow rate measuring means by the ultrasonic method, if the gas type is changed with the liberalization of the gas, there is a possibility that the amplification degree is significantly increased as in the case of dew condensation. In the gas shut-off device, it is necessary to prevent the gas supply from being erroneously shut off by erroneously determining the occurrence of condensation even if the amplification level is increased in a short period of time by changing the gas type.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a gas shut-off device that can effectively avoid the risk of misjudging a change in gas type as occurrence of condensation. To do.

  In order to solve the above-described problems, a gas cutoff device according to the present invention transmits and receives a pair of ultrasonic transceivers installed on the upstream side and the downstream side of a measurement channel, and the pair of ultrasonic transceivers. Switching means for switching, and amplification means for adjusting and amplifying the signal amplification degree so that the received ultrasonic signal has an amplitude within a predetermined range in the ultrasonic transmitter / receiver set on the receiving side by the switching means And an ultrasonic wave transmitted from one of the ultrasonic transceivers is measured by a propagation time measuring means for measuring a propagation time until the other ultrasonic transceiver is received, and the propagation time measuring means. A flow rate calculation means for calculating a gas flow rate from a propagation time and when the amplification degree adjusted by the amplification means changes beyond a determination value set according to the propagation time, dew condensation occurs in the measurement channel. Occurs In which the determining a configuration that includes a condensation determining means.

  In the present invention, with the above configuration, there is an effect that it is possible to provide a gas cutoff device capable of effectively avoiding the possibility of erroneously determining the change of the gas type as the occurrence of condensation.

It is a block diagram which shows the structural example of the gas cutoff apparatus which concerns on Embodiment 1 of this invention. (A) is a schematic diagram explaining an example of determining operation of a zero cross point from a received signal in the gas shut-off device shown in FIG. 1, and (B) is a schematic diagram explaining an example of adjusting an amplification degree by an amplifying unit. It is. In the gas cutoff device shown in FIG. 1, it is a schematic diagram explaining the determination value of the amplification degree for dew condensation determination accompanying the difference in propagation time. It is a flowchart which shows an example of the dew condensation determination in the gas cutoff device shown in FIG. It is a block diagram which shows the structural example of the gas cutoff apparatus which concerns on Embodiment 2 of this invention. It is a flowchart which shows an example of the dew condensation determination in the gas cutoff device shown in FIG. It is a flowchart which shows the other example of the dew condensation determination shown in FIG. It is a flowchart which shows an example of the dew condensation determination in the gas cutoff device which concerns on Embodiment 3 of this invention.

  A typical gas shut-off device according to the present invention includes a pair of ultrasonic transmitters / receivers installed on an upstream side and a downstream side of a measurement channel, switching means for switching transmission / reception of the pair of ultrasonic transmitters / receivers, In the ultrasonic transmitter / receiver set on the receiving side by the switching unit, an amplifying unit that adjusts and amplifies the amplitude of the signal so that the received ultrasonic signal has an amplitude within a predetermined range; and the ultrasonic transmitter / receiver A propagation time measuring means for measuring a propagation time until an ultrasonic wave transmitted from one of the devices is received by the other ultrasonic transceiver; and a gas flow rate from the propagation time measured by the propagation time measuring means. When the flow rate calculating means to be calculated and the amplification degree adjusted by the amplifying means have changed beyond a determination value set according to the propagation time, condensation has occurred in the measurement flow path. judge, And exposure determination unit, a Configurations which comprises a.

  According to the above configuration, not only the amplification degree of the received signal by the amplification means is greatly increased but also exceeds the determination value of the amplification degree set according to the propagation time of the ultrasonic wave, It is determined that condensation has occurred. Large changes in the degree of amplification can occur not only when condensation occurs in the measurement channel, but also when the gas type is changed. The degree of increase is small. Since the propagation time of ultrasonic waves varies with different gas types, an upper limit value of amplification is set for the propagation time, and this upper limit value is a judgment value for distinguishing changes in gas types or occurrence of condensation. Used as This makes it possible to distinguish between the occurrence of dew condensation and the change in gas type, thereby effectively avoiding the possibility of misjudging the change in gas type as the occurrence of dew condensation.

  The gas shut-off device having the above-described configuration further includes temperature measuring means for measuring the gas temperature in the measurement flow path, and the determination value is set according to the propagation time and the gas temperature. May be.

  In the gas shut-off device having the above configuration, a plurality of the determination values may be set in association with a plurality of predetermined ranges of the propagation time set in advance.

  In the gas shut-off device having the above-described configuration, the amplification degree and the propagation time used by the dew condensation determination unit are predetermined values that are set based on one measurement value or a first predetermined time, respectively. The configuration may be an average value of a plurality of measurement values measured within the measurement time.

  Further, the gas shut-off device having the above-described configuration further includes at least one of a shut-off means for shutting off the gas and a notifying means for notifying the occurrence of dew condensation. When it is determined that condensation has occurred, at least one of the blocking means and the notification means may be configured to operate at a second predetermined time.

  Hereinafter, typical embodiments of the present invention will be described with reference to the drawings. In the following description, the same or corresponding elements are denoted by the same reference symbols throughout the drawings, and redundant description thereof is omitted.

(Embodiment 1)
[Configuration of gas shut-off device]
First, a typical configuration of the gas cutoff device according to the first embodiment will be specifically described with reference to FIG.

  As shown in FIG. 1, the gas cutoff device according to the first embodiment includes a pair of ultrasonic transmitters / receivers 2 and 3 installed in the measurement channel 1, a flow rate measurement unit 20, a control unit 21, and a cutoff unit. Means 22 and notification means 23 are provided. The flow rate measuring unit 20 includes a switching unit 4, a transmission unit 5, a reception unit 6, an amplification unit 7, a reference comparison unit 8, a reference voltage setting unit 9, an arrival point determination unit 10, a propagation time measurement unit 11, a flow rate calculation unit 12, And dew condensation determination means 13. The specific configurations of the measurement channel 1, the ultrasonic transceivers 2 and 3, the flow rate measuring unit 20, the control unit 21, the blocking unit 22, and the notification unit 23 are not particularly limited, and a known configuration is preferably used. it can.

  The measurement flow path 1 is provided in a part of the gas pipe 30 and includes an installation surface 1a that is a top surface (upper surface) and an opposing surface 1b that is a bottom surface (lower surface) that faces the installation surface 1a. Yes. The ultrasonic transmitters / receivers 2 and 3 are both installed on the installation surface 1a which is the same side surface of the measurement flow path 1. The first ultrasonic transmitter / receiver 2 is located on the upstream side and the first ultrasonic transmitter / receiver 2 on the downstream side. Two ultrasonic transceivers 3 are located. Therefore, in this embodiment, the ultrasonic transmitters / receivers 2 and 3 are arranged by the V-path method.

  As shown in FIG. 1, the ultrasonic waves are transmitted from the upper installation surface 1a toward the lower facing surface 1b, and reflected by the facing surface 1b toward the installation surface 1a. Therefore, the installation surface 1a is an ultrasonic transmission surface or reception surface (transmission / reception surface), and the opposing surface 1b is an ultrasonic reflection surface. In the ultrasonic transmission / reception example shown in FIG. 1, the ultrasonic transmitter / receiver 2 is on the transmission side and the ultrasonic transmitter / receiver 3 is on the reception side, but transmission / reception is switched by the switching means 4 as will be described later.

  An arrow P1 shown in FIG. 1 is a propagation path of an ultrasonic wave (transmission wave) transmitted from the transmission-side ultrasonic transmitter / receiver 2 and reaches the opposing surface 1b, and an arrow P2 indicates that the transmission wave is reflected by the opposing surface 1b. It is a propagation path until it becomes a reflected wave and reaches the ultrasonic transceiver 3 on the receiving side. The transmission wave forms an angle θ with respect to the gas flow direction V.

  The switching unit 4 switches one of the ultrasonic transceivers 2 and 3 to the transmission side and the other to the reception side. The transmission means 5 transmits ultrasonic waves from the ultrasonic transceivers 2 and 3 switched to the transmission side by the switching means 4. The reception unit 6 causes the ultrasonic transmitters / receivers 3 and 2 switched to the reception side by the switching unit 4 to receive the reflected waves of the ultrasonic waves. The amplifying means 7 adjusts the amplification level (gain) of the received signal and amplifies it so that the received ultrasonic signal (received signal) has an amplitude within a predetermined range in the receiving side ultrasonic transceivers 2 and 3. To do.

  The reference comparison means 8 compares the received signal amplified by the amplification means 7 with a preset reference voltage. The reference voltage setting unit 9 outputs a reference voltage based on the output of the amplification unit 7 to the reference comparison unit 8. The arrival point determination means 10 determines the arrival point of the ultrasonic wave from the output of the reference comparison means 8 and the reception signal amplified by the amplification means 7. The propagation time measurement unit 11 measures the propagation time of the ultrasonic wave from the output of the arrival point determination unit 10. The flow rate calculation means 12 calculates the gas flow rate from the propagation time measured by the propagation time measurement means 11.

  The condensation determination means 13 determines that condensation has occurred in the measurement flow path 1 when the amplification degree adjusted by the amplification means 7 has changed beyond a determination value set according to the propagation time. (Condensation determination is performed). Details of the condensation determination will be described later. The control unit 21 controls the flow rate measurement operation and the dew condensation determination operation by the flow rate measurement unit 20 having the above-described configuration, and controls the shutoff operation of the gas pipe 30 by the shutoff unit 22. The shut-off means 22 shuts off the gas supply in the gas pipe 30 under the control of the control means 21.

  The notification unit 23 notifies the occurrence of condensation under the control of the control unit 21. The notification means 23 may be configured to notify not only the occurrence of condensation but also the interruption of gas supply accompanying this, and in addition to the occurrence of condensation and interruption of gas supply, other abnormalities are notified. It may be configured to. The notification means 23 may be in the form of notifying the abnormality by providing a display, a light emitting element, a sound alarm device, or the like in the gas shut-off device, or for a gas user or a gas supply company. It may be in the form of reporting by communication means, or in the form of reporting using the Internet. In addition, since the notification unit 23 is not an essential component of the gas cutoff device, for example, a known display device, light emitting device, or sound alarm device may be added as the notification unit 23.

  In the gas shut-off device having the above configuration, the flow rate measurement by the flow rate measurement unit 20 under the control of the control unit 21 will be described. The control means 21 operates the transmission means 5 in response to the start of the flow rate measurement, and transmits ultrasonic waves from one of the ultrasonic transceivers 2 and 3, for example, the first ultrasonic transceiver 2 and measures the propagation time. The means 11 is operated to start timing. A transmission wave (arrow P1) from the first ultrasonic transmitter / receiver 2 propagates through the gas in the measurement channel 1, is reflected by the facing surface 1b to become a reflected wave (arrow P2), and the second ultrasonic wave Received by the transceiver 3.

  The received ultrasonic signal (reception signal) is output to the amplifying means 7 via the receiving means 6. The amplifying means 7 adjusts the amplification degree (gain) of the received signal under the control of the control means 21 and amplifies the received signal waveform to have a constant amplitude. A method for adjusting the amplification degree will be described later.

  The reception signal amplified by the amplification means 7 is output to the reference comparison means 8, the reference voltage setting means 9, and the arrival point determination means 10. The reference voltage setting unit 9 generates a reference voltage having a predetermined ratio with respect to the peak voltage of the output of the amplification unit 7 and outputs the reference voltage to the reference comparison unit 8. The reference comparison means 8 compares the output (amplified received signal) of the amplification means 7 with the output (reference voltage) from the reference voltage setting means 9 and outputs the comparison result to the arrival point determination means 10. The arrival point determination means 10 determines a zero-cross point, which will be described later, as an ultrasonic arrival point and outputs it to the propagation time measurement means 11. The propagation time measuring means 11 measures the time from the start of time measurement to the arrival point as the propagation time.

  The control means 21 switches the transmission / reception of the ultrasonic transmitters / receivers 2 and 3 by the switching means 4, transmits the ultrasonic waves from the second ultrasonic transmitter / receiver 3, and the first ultrasonic transmitter / receiver 2 in the same manner as described above. While receiving, the propagation time measuring means 11 measures the propagation time. Then, the series of ultrasonic transmission / reception operations described above are repeated a preset number of times. The measured propagation time is output to the flow rate calculation means 12, and the flow rate value is calculated. In addition, since the well-known method can be used suitably for the calculation method of a flow value, concrete description is abbreviate | omitted.

[Adjustment of amplification degree]
Next, with respect to a representative example of a method for adjusting the amplification degree in the amplification means 7 and the condensation determination based on the amplification degree, together with the arrival point determination method by the arrival point determination means 10, FIGS. This will be specifically described with reference to FIG.

  As shown in FIG. 2A, the waveform of the received signal A (output of the amplified signal) has a plurality of peaks, but the arrival point determination means 10 usually identifies the number of waves from reception. Then, in the wave, the “first negative zero cross point p” at which the sign of the reception signal A changes from positive to negative is determined as the arrival point. In the present embodiment, the zero cross point p of the fourth wave is determined.

  The reference voltage setting means 9 sets a voltage value that is the midpoint of the peak voltage values of the third wave and the fourth wave of the received signal A as the reference voltage D in order to determine the zero-cross point p of the fourth wave. The reference comparison unit 8 compares the received signal A with the reference voltage D, and outputs the output signal to the arrival point determination unit 10 at the time when the magnitude relationship is reversed, as indicated by the signal output timing t in FIG. B is output. The arrival point determination means 10 determines the first negative zero-cross point p shown in FIG. 2A as an ultrasonic arrival point, and outputs an output signal C to the propagation time measurement means 11.

  Here, the reception signal A is amplified by the amplification means 7 so as to have a constant amplitude. For example, as shown in FIG. 2B, the amplifying means 7 has a maximum voltage value (peak value) of the fourth wave of the received signal A within a predetermined voltage range (between the lower limit R1 and the upper limit R2 of the voltage range). The amplification degree (gain value, amplification factor) is adjusted so as to enter.

  In FIG. 2B, the solid line received signal A0 is in a predetermined voltage range, but the long broken line received signal A1 has a maximum voltage value lower than the lower limit R1 of the voltage range, and the short broken line received signal. A2 has a maximum voltage value that exceeds the upper limit R2 of the voltage range. In such a case, the amplifying means 7 adjusts the amplification degree so that the maximum voltage value falls within a predetermined voltage range under the control of the control means 21. If the received signal is A1, the gain is increased, and if the received signal is A2, the gain is decreased. Such an adjustment operation of the amplification degree is performed for each flow rate measurement.

  By the way, when the temperature of the measurement channel 1 is lower than the gas temperature, condensation may occur in the measurement channel 1. For example, the gas shut-off device provided with the flow rate measuring means 20 is installed on the ground, but the gas pipe 30 on the upstream side is often buried in the ground. The underground gas pipe 30 is in an environment where there is little temperature change even in the winter and is warmer than the outside air. However, if the gas shut-off device is in an environment exposed to the outside air, the flow rate measuring means 20 and the measurement flow provided therein are provided. Road 1 may get cold.

  As described above, when a temperature difference occurs in the gas flow path between the upstream side and the downstream side, and the gas is wet, dew condensation occurs in the measurement flow path 1. If water (condensation water) generated by condensation is present in the measurement flow path 1, the degree of amplification will be significantly higher than usual. Since dew condensation occurs due to the inflow of moist gas, the degree of amplification increases rapidly in units of hours or days. However, if the gas type is changed, there is a possibility that the amplification degree is significantly increased as in the case of condensation. With the liberalization of gas, it is necessary for the gas shutoff device to assume that the gas type to be measured changes due to the adjustment of heat quantity or diversification of raw material suppliers.

  Here, it is clear that the increase in amplification when condensation occurs can be distinguished from the increase in amplification by changing the gas type, as schematically shown in FIG. 3, based on the propagation time of ultrasonic waves. It was.

  In the graph shown in FIG. 3, the vertical axis represents the amplification degree (gain value), and the horizontal axis represents the ultrasonic wave propagation time. For example, there are five types of gas i, gas i, gas ii, gas iii, gas iv and gas v, and the propagation time of each of these gas types is 0 to t1 seconds (predetermined range Pi). T1 to t2 seconds (predetermined range P-ii), t2 to t3 seconds (predetermined range P-iii), t3 to t4 seconds (predetermined range P-iv), and t4 seconds or more (predetermined range Pv) Let's enter.

  In the amplifying means 7, d0 is set as the initial value of the amplification factor at the time of shipment, but the upper limit values of the amplification factors in the gases iv are different. Further, the upper limit values (determination values) of the amplification degrees in the gases i to v are d5, d4, d3, d2, and d1, respectively, and d5> d4> d3> d2> d1> d0. In the example shown in FIG. 3, the propagation time becomes longer in the order of gases iv, and the upper limit value of the amplification degree decreases. Accordingly, the amplification degree-propagation time graph has a descending step shape. If this is an approximate curve, the long broken line graph of FIG. 3 is obtained.

  When the gas type is changed in the gas cutoff device, for example, when the gas type is changed from the initial gas type to the gas ii, the propagation time tx is assumed to fall within the range of t1 to t2. In this case, even if the degree of amplification increases in units of hours or days, the upper limit value d4 or less (basically the approximate curve or less) is obtained (for example, the position of the white circle symbol). On the other hand, if condensation occurs, even if the propagation time is the same tx, the amplification level increases until it exceeds the upper limit d4 (for example, a black circle symbol).

  That is, even when the propagation time is within the same range, when dew condensation occurs, the degree of amplification greatly exceeds the assumed upper limit value when the gas type is changed. Accordingly, the dew condensation determination means 13 of the flow rate measurement means 20 determines a determination value (FIG. 3) in which the amplification degree adjusted by the amplification means 7 is set according to the propagation time (in the range of t1 to t2 in FIG. 3, for example). Then, for example, when it changes exceeding the upper limit d4), it is determined that condensation has occurred in the measurement channel 1. As described above, a plurality of determination values may be set in association with a plurality of predetermined ranges (in FIG. 3, predetermined ranges Pi to Pv) of the propagation time set in advance (see FIG. 3). 3, the upper limit value d5 to d1).

[Dew condensation determination]
Next, a typical example of the condensation determination by the condensation determination means 13 will be specifically described with reference to FIG.

  First, the dew condensation determination unit 13 acquires the amplification degree changed by the amplification unit 7 (step S11) and also acquires the propagation time measured by the propagation time measurement unit 11 (step S12). Then, it is determined whether or not the acquired amplification degree exceeds an amplification degree determination value set for the acquired propagation time (step S13). If the amplification degree does not exceed the determination value (NO in step S13), the condensation determination is terminated.

  If the degree of amplification exceeds the determination value (YES in step S13), the condensation determination means 13 determines that condensation has occurred in the measurement channel 1 (step S14), and ends the condensation determination. If condensation occurs, the gas flow rate cannot be measured accurately. When the gas flow rate cannot be measured accurately, it is necessary to shut off the gas supply. Therefore, if the dew condensation determination unit 13 determines that the dew condensation has occurred, the control unit 21 operates the blocking unit 22 to supply the gas. In addition to blocking, the notification means 23 notifies the occurrence of condensation.

  As described above, in the present embodiment, not only the amplification degree (gain value) of the received signal by the amplifying means 7 is greatly increased, but also the amplification degree determination value set in accordance with the propagation time of the ultrasonic wave is set. If it exceeds, it is determined that condensation has occurred in the measurement channel 1. A large change in the degree of amplification can occur not only when condensation occurs in the measurement flow path 1 but also when the gas type is changed. However, when the gas type is changed, amplification is greater than when condensation occurs. The degree of increase in degree becomes smaller. Since the propagation time of ultrasonic waves varies with different gas types, an upper limit value of amplification is set for the propagation time, and this upper limit value is a judgment value for distinguishing changes in gas types or occurrence of condensation. Used as This makes it possible to distinguish between the occurrence of dew condensation and the change in gas type, thereby effectively avoiding the possibility of misjudging the change in gas type as the occurrence of dew condensation.

(Embodiment 2)
In the first embodiment, the dew condensation determination means 13 sets a plurality of determination values for distinguishing the change of the gas type or the occurrence of the dew condensation based on the propagation time that differs depending on the gas type. 2, a plurality of determination values are set based on the propagation time and the gas temperature in the measurement channel 1. An example of such a configuration will be specifically described with reference to FIGS.

  As shown in FIG. 5, the gas shutoff device according to the present embodiment is similar to the gas shutoff device according to the first embodiment, and a pair of ultrasonic transceivers 2 and 3 installed in the measurement channel 1. The flow rate measuring means 20, the control means 21, the blocking means 22, and the notification means 23 are provided. The flow rate measuring means 20 includes a switching means 4, a transmitting means 5, a receiving means 6, an amplifying means 7, and a reference comparison. In addition to means 8, reference voltage setting means 9, arrival point determination means 10, propagation time measurement means 11, flow rate calculation means 12, and dew condensation determination means 13, temperature measurement means 14 that measures the gas temperature in the measurement channel 1. It has.

  The temperature measuring means 14 may be any means as long as it can measure the gas temperature in the measurement flow path 1 and output it to the dew condensation determining means 13, and its specific configuration is not particularly limited. As the temperature measuring means 14, for example, various known temperature sensors can be suitably used. Since a plurality of determination values are set according to the propagation time and the gas temperature, the dew condensation determination unit 13 acquires the propagation time from the propagation time measurement unit 11 and the gas temperature from the temperature measurement unit 14. The determination value set for the propagation time and the gas temperature is compared with the amplification degree adjusted by the amplification means 7. If the amplification degree has changed beyond the determination value, it is determined that condensation has occurred in the measurement channel 1.

  The gas temperature should just be set to the some range according to the use condition or use environment, etc. of a gas cutoff device. Examples of the range of the gas temperature include, for example, less than −10 ° C. (predetermined range T−i), −10 ° C. or more and less than + 20 ° C. (predetermined range T-ii), + 20 ° C. or more and less than + 40 ° C. (predetermined range T -Iii), + 40 ° C. or higher (predetermined range T-iv), and the like, but are not particularly limited. As the plurality of determination values, for example, with respect to the propagation time of the predetermined range Pi (0 to t1 seconds) described in the first embodiment, the predetermined ranges Ti, T-ii, T-iii, and T A configuration in which upper limit values d51, d52, d53, and d54 are set for each of -iv can be given. The plurality of determination values may be tabulated and stored in a storage unit (not shown) (for example, provided in the control unit 21) so that the dew condensation determination unit 13 can refer to it in a timely manner.

  Next, a typical example of the condensation determination by the condensation determination unit 13 will be specifically described with reference to FIG.

  As shown in FIG. 6, the dew condensation determination unit 13 first acquires the amplification degree changed by the amplification unit 7 (step S21), acquires the propagation time from the propagation time measurement unit 11 (step S22), and further the temperature. The gas temperature is acquired from the measuring means 14 (step S23). Then, it is determined whether or not the amplification degree determined to be equal to or greater than the initial value exceeds a determination value set for the acquired propagation time and gas temperature (step S24).

  If the degree of amplification does not exceed the determination value (NO in step S24), the condensation determination is terminated. If the degree of amplification exceeds the determination value (YES in step S24), the dew condensation determination means 13 determines that dew condensation has occurred in the measurement flow path 1 (step S25), and ends the dew condensation determination. When the dew condensation determination unit 13 determines the occurrence of dew condensation, the control unit 21 operates the blocking unit 22 to block the gas supply and causes the notification unit 23 to notify the occurrence of dew condensation.

  Since the speed of sound can change due to a change in temperature, if the gas temperature changes due to the influence of outside air, for example, in the measurement channel 1, the speed of sound of the ultrasonic wave propagating in the gas also changes, and the propagation time can also change. Within the range of room temperature, changes in propagation time due to changes in gas temperature are often negligible. However, depending on the usage environment of the gas shut-off device or the specific gas type that can be changed, it may be preferable to consider the change in propagation time due to the change in gas temperature in the dew condensation determination. Thus, as in the present embodiment, by setting a plurality of determination values for the propagation time and the gas temperature, it is possible to realize even better dew condensation determination.

  Note that the dew condensation determination in the present embodiment may include a step of determining whether or not the amplification degree changed by the amplifying unit 7 is equal to or higher than the initial value. Specifically, as shown in FIG. 7, the dew condensation determination means 13 acquires the amplification degree changed by the amplification means 7 (step S21), and determines whether this amplification degree is equal to or greater than the initial value. (Step S26). If it is not equal to or greater than the initial value (NO in step S26), the condensation determination is terminated. If it is equal to or greater than the initial value (YES in step S26), the condensation determination after the acquisition of the propagation time (step S22) is performed. The subsequent dew condensation determination is the same as the flow shown in FIG.

  In the flow rate measuring unit 20, as long as the gas flow rate is measured, the propagation time measuring unit 11 acquires the ultrasonic wave propagation time. However, the measurement of the gas temperature by the temperature measuring unit 14 is not essential for the measurement of the gas flow rate. If the condensation determination is terminated when the acquired amplification degree is less than the initial value in the condensation determination means 13, there is no need to acquire the gas temperature, so that the frequency measurement of the gas temperature by the temperature measurement means 14 can be reduced. it can. If it is determined whether or not the amplification degree is equal to or higher than the initial value, the determination value can be set as a value added to the initial value, not as an absolute value as an upper limit of the amplification degree. In this case, only the added value can be classified and tabulated based on the propagation time and gas temperature.

(Embodiment 3)
In the first and second embodiments, the dew condensation determination means 13 uses a single measured value for the propagation time used in the dew condensation determination (propagation time and gas temperature in the second embodiment). In this case, an average value of measured values measured a plurality of times within a predetermined time starting from a predetermined time is used as the propagation time (and gas temperature). An example of such a configuration will be specifically described with reference to FIG.

  As shown in FIG. 8, first, the dew condensation determination means 13 acquires the amplification degree, the propagation time, and the gas temperature from the predetermined time (step S31), and determines whether or not the predetermined measurement time has elapsed. (Step S32). If it has not elapsed (NO in step S32), the dew condensation determination means 13 repeats acquisition of the amplification degree, propagation time, and gas temperature (return to step S31). If it has elapsed (YES in step S32), an average value of the measured values of the amplification degree, the propagation time, and the gas temperature acquired within the measurement time is calculated (step S33).

  If these average values are obtained, the condensation determination means 13 determines whether or not the average value of the amplification degree determined to be equal to or higher than the initial value exceeds the determination value set for the average value of the propagation time and the gas temperature. Is determined (step S34). If the average value of the degree of amplification does not exceed the determination value (NO in step S34), the dew condensation determination is terminated. If the average value of the degree of amplification exceeds the determination value (YES in step S34), the dew condensation determination means 13 determines that dew condensation has occurred in the measurement flow path 1 (step S35) and ends the dew condensation determination. To do. When the dew condensation determination unit 13 determines the occurrence of dew condensation, the control unit 21 operates the blocking unit 22 to block the gas supply and causes the notification unit 23 to notify the occurrence of dew condensation.

  In the present embodiment, the average value is an average value of a plurality of measurement values (acquired values) measured within a predetermined measurement time set with a predetermined time as a starting point. Moreover, the control means 21 can control the interruption means 22 and the notification means 23 to operate at a predetermined time. Although a specific predetermined time can be set as appropriate, a time belonging to a midnight time zone can be set as the first predetermined time serving as a starting point for obtaining the average value. As the second predetermined time for operating 23, a time belonging to the morning or morning time zone can be set.

  Condensation is likely to occur at night when the outside air temperature usually decreases. Here, especially at midnight, since the gas user is often asleep, it is assumed that the amount of gas used is very small. In addition, it is assumed that gas supply companies are usually closed at midnight. Therefore, the dew condensation determination means 13 uses a first predetermined time belonging to the midnight time zone as a starting point, and provides a plurality of measurement values (acquired values) for the amplification degree, the propagation time, and the gas temperature within a predetermined measurement time. By acquiring and calculating an average value and determining condensation, the condensation determination can be performed at a more suitable timing.

  In addition, by setting the second predetermined time as a time belonging to the morning or morning time zone, the control means 21 is cut off in anticipation of the time zone when the gas user wakes up and the gas supplier starts business. The means 22 and the notification means 23 are operated. Therefore, it is possible to avoid a situation in which the gas supply is shut off and the occurrence of condensation is notified in a time zone in which the gas user or the gas supply company cannot respond.

  In this way, by using an average value of a plurality of measurement values as the propagation time (and gas temperature), it is possible to effectively suppress misjudgment derived from propagation time (or measurement variation of gas temperature). As a result, it is possible to determine the condensation more accurately. Further, by calculating an average value of amplification degree and propagation time (and gas temperature) starting from a predetermined time, the dew condensation determination can be performed at a suitable timing.

  Here, in the present embodiment, the average value is calculated for all of the amplification degree, propagation time, and gas temperature. However, as long as the configuration does not require the use of the gas temperature as in the first embodiment. The average value of the measured values may be calculated for the amplification degree and the propagation time. The average value may be calculated using a measurement value measured a plurality of times starting from a predetermined time, and the number of measurement values is not particularly limited.

  In the first and second embodiments and the third embodiment, the ultrasonic transmitters / receivers 2 and 3 installed in the measurement channel 1 are in a V-path method as illustrated in FIG. 1 or FIG. is set up. However, the present invention is not limited to this, and the ultrasonic transceivers 2 and 3 may be installed by a Z-pass method or the like.

  It should be noted that the present invention is not limited to the description of the above-described embodiment, and various modifications are possible within the scope shown in the scope of the claims, and are disclosed in different embodiments and a plurality of modifications. Embodiments obtained by appropriately combining the technical means are also included in the technical scope of the present invention.

  The present invention can be widely used in the field of gas shut-off devices and the like that require dew condensation determination, and in particular, can be suitably used in the field of gas shut-off devices that can respond to changes in gas types.

DESCRIPTION OF SYMBOLS 1 Measurement flow path 1a Installation surface 1b Opposite surface 2 Ultrasonic transmitter / receiver 3 Ultrasonic transmitter / receiver 4 Switching means 5 Transmitting means 6 Receiving means 7 Amplifying means 8 Reference comparison means 9 Reference voltage setting means 10 Arrival point determination means 11 Propagation time measurement Means 12 Flow rate calculation means 13 Condensation determination means 14 Temperature measurement means 20 Flow rate measurement means 21 Control means 22 Shut-off means 23 Notification means 30 Gas pipe

Claims (5)

A pair of ultrasonic transceivers installed on the upstream side and downstream side of the measurement channel,
Switching means for switching between transmission and reception of the pair of ultrasonic transceivers;
In the ultrasonic transmitter / receiver set on the receiving side by the switching means, amplification means for adjusting and amplifying the signal amplification degree so that the received ultrasonic signal has an amplitude within a predetermined range;
A propagation time measuring means for measuring a propagation time until the ultrasonic wave transmitted from one of the ultrasonic transceivers is received by the other ultrasonic transceiver;
A flow rate calculating means for calculating a gas flow rate from the propagation time measured by the propagation time measuring means;
Dew condensation determination means for determining that dew condensation has occurred in the measurement flow path when the amplification degree adjusted by the amplification means has changed beyond a determination value set according to the propagation time; ,
It is characterized by having,
Gas shut-off device. Furthermore, a temperature measuring means for measuring the gas temperature in the measurement channel is provided,
The determination value is set according to the propagation time and the gas temperature,
The gas cutoff device according to claim 1. A plurality of determination values are set in association with a plurality of predetermined ranges of the propagation time set in advance, respectively,
The gas cutoff device according to claim 1 or 2. The amplification degree and the propagation time used in the dew condensation determination unit are each measured once or measured multiple times within a predetermined measurement time set starting from a first predetermined time. It is an average value of values,
The gas cutoff device according to any one of claims 1 to 3. Furthermore, it comprises at least one of a shut-off means for shutting off the gas and a notifying means for notifying the occurrence of condensation,
When it is determined by the condensation determination means that condensation has occurred in the measurement flow path, at least one of the blocking means and the notification means operates at a second predetermined time,
The gas cutoff device according to any one of claims 1 to 4.

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