JP2012026822A - Gas shut-off device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the setting of a reference voltage for detecting an ultrasonic signal.SOLUTION: A gas shut-off device comprises: an upstream side transmitter/receiver 1 and a downstream side transmitter/receiver 2 for transmitting/receiving an ultrasonic signal; amplification means 5 for amplifying the received ultrasonic signal to a prescribed level; reference voltage comparison means 6 for detecting the amplified ultrasonic signal; reference voltage setting means 13 for setting a reference voltage to the middle wave of a reception wave as an initial set value in a case of adjusting a reference voltage, and for outputting it to the reference voltage comparison means 6; propagation time measurement means 15 for, when a prescribed reception wave is detected by the reference voltage comparison means 6, measuring the propagation time of the reception wave; and reference voltage arithmetic means 18 for calculating a time difference between the measured propagation time and the previous propagation time to determine whether or not it is equal to or more than a prescribed value by propagation time difference comparison means 16, for storing the reference voltage setting only by the prescribed number in reference voltage storage means 17 when the time difference is equal to or more than the prescribed propagation time difference, and for, when it reaches the stored number, calculating a reference value to be set in a case of measuring a flow rate so as to output it to the reference voltage setting means 13.

Description

  The present invention relates to a gas shut-off device, and more particularly to a gas shut-off device that performs flow rate measurement with ultrasonic waves and performs safety monitoring.

  Conventionally, as this type of gas shut-off device, there has been one as shown in FIGS. 3 and 4 (see, for example, Patent Document 1).

  The configuration of the gas shut-off device disclosed in Patent Document 1 will be briefly described with reference to FIGS. 3 and 4.

  An upstream transmitter / receiver 1 that transmits ultrasonic waves and a downstream transmitter / receiver 2 that receives ultrasonic waves are disposed in a flow path (not shown) through which the fluid to be measured flows. The switching unit 3 switches transmission / reception of the ultrasonic transducer (upstream transmitter / receiver 1 or downstream transmitter / receiver 2), and the ultrasonic transducer (upstream transmitter / receiver 1 or upstream) selected by the switching unit 3 on the transmission side. A transmission signal is sent from the transmission means 4 to the downstream transmitter / receiver 2), and the amplification means 5 receives the signal received by the ultrasonic transducer selected on the reception side by the switching means 3 with a gain according to an instruction from the control means 11. Amplify.

  The reference voltage comparing means 6 compares the signal amplified by the amplifying means 5 with the reference voltage, and the determination means 7 generates ultrasonic waves from the output of the reference voltage comparing means 6 and the signal amplified by the amplifying means 5. The arrival time of is determined. The repeater 8 counts the signal from the determiner 7 and outputs a repeat signal to the controller 11 a preset number of times.

  The time measuring means 9 measures the time when the preset number of times is counted by the repeating means 8, and the flow rate calculating means 10 calculates the flow rate from the time counted by the time measuring means 9. The control unit 11 receives signals from the flow rate calculation unit 10 and the repetition unit 8 and controls the operations of the transmission unit 4 and the amplification unit 5. The output width timer 12 measures the output time of the reference voltage comparator 6 and the reference voltage setting unit 13 sets the reference voltage of the reference voltage comparator 6.

Next, the operation of the configuration of the conventional gas cutoff device will be described. After the power is turned on, the control means 11 first performs gain adjustment and reference voltage setting as an initial setting operation. After adjusting the gain so that the signal first received by the ultrasonic transducer on the receiving side has a constant amplitude, the reference voltage setting means 13 sets the reference voltage to the lowest voltage in the setting range. After setting the lowest reference voltage, the control means 11 sets the number of repetitions of the repetition means 8 to one, operates the transmission means 4 and transmits an ultrasonic signal from the upstream side transceiver 1 upstream side transceiver 1 The transmitted ultrasonic signal propagates through the flow path, is received by the downstream transceiver 2, is amplified by the amplification means 5, and is output to the reference voltage comparison means 6 and the determination means 7. FIG. 4 shows the received signal after amplification. Here, the reference voltage comparing means 6 compares the output (received signal) of the amplifying means 5 with the reference voltage, and outputs an output signal to the output width measuring means 12 and the judging means 7 when the magnitude relationship is inverted. The output width timing means 12 starts timing when an output signal from the reference voltage comparison means 6 is input, and again, the output voltage of the reference voltage comparison means 6 until the time when the magnitude relationship between the output of the amplification means 5 and the reference voltage is reversed. The time Tw (output width) when the time is “L” is measured.

  The judging means 7 judges the first negative zero cross point at which the sign of the output of the amplifying means 5 changes from positive to negative as an ultrasonic arrival point, and outputs an output signal to the repeating means 8. The output width measuring means 12 outputs the measured output width to the reference voltage setting means 13. The reference voltage setting means 13 increases the reference voltage by one control unit (for example, 2 mV) in the variable range of the reference voltage.

  When the control means 11 inputs from the repetition means 8 that the set number of repetitions has been completed, the control means 11 operates the transmission means 4 again to transmit an ultrasonic signal from the upstream side transceiver 1, and the operations up to this point are performed. The process is repeated until the reference voltage setting unit 13 sets the maximum voltage within the reference voltage setting range. When the reference voltage setting means 13 finishes setting up to the maximum voltage of the reference voltage, the reference voltage setting means 13 has a plurality of outputs in which the output width measured by the output width timing means 12 when the reference voltage is changed from the minimum to the maximum greatly changes. The reference voltage is set at the midpoint between the inflection points of the inflection points having the maximum voltage. FIG. 4 is a diagram showing the value measured by the output width measuring means 12 when the reference voltage setting means 13 changes the reference voltage from the minimum to the maximum. Since the value measured by the output width measuring means 12 is the time width of the output signal of the reference voltage comparing means 6, it is near the peak voltage of each wave (1 wave, 2 waves, 3 waves,...) Of the received signal (FIG. 5). , When the reference voltage is present at p1, p2, p3..., The output width is minimum (corresponding to p1, p2, p3..., Tp1, Tp2, Tp3. .

  When the reference voltage is increased from the peak voltage and the peak voltage is exceeded, the output width measured by the output width measuring means 12 suddenly increases, and as shown in FIG. , Tp3... For example, when the reference voltage is near the peak p2 of the two waves and exceeds the peak voltage p2 of the two waves, the inflection point is Tp2. In this case, the reference voltage corresponding to the inflection point of the output width is a voltage near the peak voltage of each wave of the received signal. The interval between the inflection points (reference voltage interval) is the voltage difference between the peak voltages of the received signal waves.

  The voltage difference between the inflection points Tp1 and Tp2 is the peak voltage difference between one and two waves of the received signal, and the voltage difference between the inflection points Tp2 and Tp3 is the peak voltage difference between the two waves of the received signal and three waves. ing. In this way, there are multiple inflection points in the change in the waveform of voltage versus output width when the reference voltage is changed from minimum to maximum, and the two inflections with the widest voltage difference between the inflection points are present. If the reference voltage is set at the midpoint of the point (Vre, the midpoint of the peak voltage of 2 waves and 3 waves in FIG. 5), the voltage at the midpoint of the largest peak voltage difference of each wave of the received signal It becomes.

Japanese Patent No. 4013697

  However, in the gas cutoff device of the above conventional configuration, in order to obtain the maximum inflection point, it is necessary to obtain the maximum inflection point (reference voltage interval) by changing the reference voltage over the entire range from the minimum to the maximum. There is a drawback that it takes a lot of setting time, and the ultrasonic signal level starts from '0' in order to make the minimum setting. If it remains without being attenuated, the maximum inflection point cannot be calculated correctly, and when the minimum setting is made, it may start from the minus side slightly from the reception level of the ultrasonic signal. The received waveform detection on the plus side may be misjudged as an inflection point, and the reference voltage cannot be set for the received wave you want to set, resulting in large variations in propagation time and flow measurement accuracy. There is a problem of poor.

  The present invention solves the above-described problems, and provides a gas cutoff device that can set a reference voltage correctly even when another signal wave is superimposed on an ultrasonic reception signal and has high measurement accuracy.

In order to solve the above-described conventional problems, a gas cutoff device of the present invention includes a pair of transceivers that transmit and receive an ultrasonic signal, and a switching unit that switches one of the pair of transceivers to a reception side and the other to a transmission side. Transmitting means for outputting a transmission signal to the transceiver set on the transmission side by the switching means, amplification means for amplifying the ultrasonic signal received by the transceiver set on the reception side by the switching means, and the amplification A reference voltage comparing means for detecting the received wave by comparing the ultrasonic signal amplified by the reference voltage, a reference voltage setting means for adjusting and setting the reference voltage, and the received wave by the reference voltage comparing means. Propagation time measuring means for measuring the propagation time of the ultrasonic signal between the pair of transceivers when detecting the predetermined wave, and flow rate calculating means for calculating the instantaneous flow rate value from the propagation time measured by the propagation time measuring means And said An abnormality determining means for determining the presence or absence of an abnormality from the flow rate obtained by the quantity calculating means, and a blocking means for cutting off the gas supply when the abnormality determination is established by the abnormality determining means. The initial value of the reference voltage is larger than the peak voltage of the first wave, and the n-th wave before the n-th wave (n is an integer of 3 or more) serving as a reference for measuring the propagation time used in the flow rate calculation means. While setting the reference voltage to a value smaller than the peak voltage of one wave and gradually increasing this reference voltage, the time difference between the propagation time measured this time by the propagation time measuring means and the previously measured propagation time is greater than or equal to a predetermined value. The reference voltages at the time of becoming the first are sequentially stored, the plurality of stored reference voltages are regarded as the peak voltages of each wave of the received wave, and the nth wave is determined from the peak voltages of the (n−1) th wave and the nth wave. The reference voltage to detect One in which a constant.

  Even when the echo signal and the like are superimposed before the ultrasonic signal reaches the receiving side and is at a level that does not change from the first wave of the received wave, the received wave (for example, the second wave) is still higher. Since the initial reference voltage is set to the voltage that can be detected and the peak voltage of each received wave is measured, only the peak voltage of the necessary received wave can be reliably measured. Therefore, all received waveforms are measured from the first wave one by one. A reference for measurement to calculate and calculate the reference voltage from the reference voltage difference between the received wave required for setting the reference voltage and the received wave smaller than the required received wave without waste. Since it is set as a voltage, the time required for adjusting the reference voltage can be shortened, and a necessary reference voltage for detecting a corresponding wave of a necessary received wave accurately can be set easily and without being affected by an echo wave.

  The gas cutoff device of the present invention measures the peak value of each received wave by shifting, for example, one wave due to the influence of echo and self-excitation in measuring the received wave of the ultrasonic signal in a short time. It is possible to prevent the reference voltage from being set to another wave of the received wave by mistake.

Control block diagram of gas shutoff device in embodiment 1 of the present invention The figure which shows the ultrasonic reception waveform in the same Embodiment 1. Control block diagram of a conventional gas shut-off device The figure which shows the ultrasonic reception waveform in the same gas cutoff device Operation explanatory diagram of the gas shutoff device

The first invention is a pair of transceivers for transmitting and receiving ultrasonic signals, switching means for switching one of the pair of transceivers to the receiving side and the other to the transmitting side, and transmission / reception set on the transmitting side by the switching means A transmission means for outputting a transmission signal to a transmitter, an amplification means for amplifying an ultrasonic signal received by a transceiver set on the receiving side by the switching means, and an ultrasonic signal amplified by the amplification means as a reference voltage Reference voltage comparison means for comparing and detecting the received wave, reference voltage setting means for adjusting and setting the reference voltage, and the pair of transceivers when the predetermined wave of the received wave is detected by the reference voltage comparison means A propagation time measuring means for measuring the propagation time of the ultrasonic signal between, a flow rate calculating means for calculating an instantaneous flow rate value from the propagation time measured by the propagation time measuring means, and an abnormality from the flow rate obtained by the flow rate calculating means Whether or not And the abnormality determination means that,
A cutoff means for shutting off the gas supply when the abnormality judgment is established by the abnormality judgment means, wherein the reference voltage setting means has an initial value of the reference voltage larger than the peak voltage of the first wave at the time of adjustment, and the flow rate The reference voltage is set to a value smaller than the peak voltage of the (n-1) th wave before the nth wave (n is an integer of 3 or more) which is a reference for measuring the propagation time used in the arithmetic means, and this reference voltage is gradually increased. The reference voltage at the time when the time difference between the propagation time measured this time by the propagation time measurement means and the propagation time measured last time is equal to or greater than a predetermined value is sequentially stored. The voltage is regarded as the peak voltage of each wave of the received wave, and a reference voltage for detecting the nth wave is set from the peak voltages of the (n−1) th wave and the nth wave.

  Then, when a reference voltage adjustment instruction is issued by the measurement control means, the reference voltage setting means sets an initial setting value in the middle of a plurality of waves up to the maximum wave of the ultrasonic reception wave, and a necessary reception from the intermediate wave. Measure the peak position up to the wave. The reference received voltage is detected by the reference voltage comparison means, the propagation time of the received wave to the zero cross is measured by the propagation time measurement means, and the reception signal having the next highest peak value is detected by the propagation time difference comparison means. It is determined whether or not it has shifted to a wave, and if it has shifted, the difference in propagation time becomes large, and the reference voltage setting value at that time is stored in the reference voltage storage means. In this way, among the plural received waves of the ultrasonic signal, the peak voltage of the intermediate wave is searched and the peak value of the received wave having the next highest peak value is obtained, and both are stored. Finally, the reference voltage is calculated from the peak difference voltage and output to the reference voltage setting means as the reference voltage setting value at the time of measurement. Of the plurality of received waves, the received wave is different from the received wave that originally sets the reference voltage. Can be prevented from being set erroneously, and can be easily set in a short time and has high reliability.

  The second invention is a program for causing a computer to execute all or part of the means of the shut-off device of the first invention.

  And since it is a program, a part or all of the gas interruption | blocking apparatus of this invention can be easily implement | achieved using a microcomputer etc. Also, program distribution and installation can be simplified by recording on a recording medium or distributing a program using a communication line.

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

(Embodiment 1)
FIG. 1 is a diagram showing a control block diagram of the gas shut-off device according to Embodiment 1 of the present invention, and FIG. 2 is a received waveform diagram of the control device mounted on the gas shut-off device. The same number is attached | subjected to the equivalent to a prior art example.

  Although not shown, the gas shut-off device is installed in the garden of each household, and after passing through this gas shut-off device, it is piped to the place where various gas appliances used in each home are installed, and gas is supplied. The The internal configuration of the gas cutoff device includes a flow path and a control device. A flow path (not shown) is connected to a supply port for supplying gas to each gas appliance through an inlet-side flow path from an inlet of the gas shut-off device, through a flow path at the bottom, and through an outlet-side flow path. . An upstream transmitter / receiver 1 and a downstream transmitter / receiver 2 that transmit and receive an ultrasonic signal are attached to the flow path so as to face each other in the flow direction.

  FIG. 1 is a control block diagram of the control device. A pair of transceivers (upstream transceiver 1 and downstream transceiver 2), switching means 3, transmission means 4, amplification means 5, reference voltage setting means 13, measurement control means 14, propagation time measurement means 15, propagation time difference comparison The means 16, the reference voltage storage means 17, and the reference voltage calculation means 18 constitute a flow rate detection means. An upstream transceiver 1 that transmits or receives ultrasonic waves and a downstream transceiver 2 that also receives or transmits ultrasound can be switched between transmission and reception by switching means 3. Transmitting means 4 for outputting an ultrasonic signal is connected to the upstream transceiver 1 or the downstream transceiver 2, and the switching means 3 receives the ultrasonic signal via the upstream transceiver 1 or the downstream transceiver 2. Amplifying means 5 amplifies the maximum wave of the received signal up to a predetermined signal level.

  First, an ultrasonic signal is transmitted by the transmitter / receiver 1 by the transmitter 4 and received by the transmitter / receiver 2, and the received signal from the amplifier 5 is detected by the reference voltage comparator to detect a predetermined wave in the received signal. Then, the propagation time measuring means 15 measures the propagation time from the start of transmission to reception. Next, switching is performed by the switching means 3, and similarly, an ultrasonic signal is transmitted from downstream to upstream, and the propagation time is measured. And the propagation time of the ultrasonic wave of the upstream transmitter / receiver 1 and the downstream transmitter / receiver 2 is calculated | required for every predetermined period (for example, every 2 seconds).

  The measurement control means 14 issues a reference voltage setting instruction or the like in order to start the flow rate measurement. For example, it is started by a switch operation (not shown) or a notification by communication. Here, when a reference voltage adjustment request is received from the measurement control means 14 by operating a test switch or the like, the reference voltage setting means 13 outputs an initial reference voltage.

  On the other hand, when receiving the measurement start signal from the measurement control unit 14, the transmission unit 4 periodically outputs an ultrasonic transmission signal to, for example, the upstream side transceiver 1 and receives it by the downstream side transceiver 2. The received signal is amplified to a predetermined level by the amplifying means 5 and is always kept at a constant voltage level. The reference voltage comparison unit 6 compares the amplified ultrasonic signal from the amplification unit 5 with a reference voltage set value, and determines that a received wave has been detected if it is determined that the reference voltage set value is exceeded. The received ultrasonic signal gradually increases in amplitude level from the first wave and is usually up to the seventh wave level. The number of waves varies depending on the flow path system.

  Usually, there is a relationship of the peak value of the first wave <the peak value of the second wave <... <The peak value of the nth wave, and the initial value of the reference voltage is a value that can detect the second and subsequent waves. In this embodiment, the adjustment is started by setting an intermediate value between the peak value of the first wave and the peak value of the second wave, which is known in advance, using the actual machine.

  The propagation time measuring means 15 measures the propagation time from the start of transmission of the ultrasonic signal to the zero cross of the received wave when the reference voltage comparing means 6 detects the received wave. The propagation time difference comparison means 16 stores the measured propagation time in a time series, obtains a difference from the previous propagation time, determines whether a predetermined time difference or more is detected, and determines whether the predetermined difference or more is detected after the received wave. It is determined that n waves have been reached, and a detection signal is output.

  When the reference voltage storage unit 17 receives a detection signal with a difference in propagation time from the propagation time difference comparison unit 16, the reference voltage storage unit 17 stores the reference voltage setting value currently set by the reference voltage comparison unit 6. Since the reference voltage stored at this time corresponds to the peak voltage of each waveform, the reference voltage storage means 17 determines the reference voltage value and the first of the necessary received waves from the peak voltage of the second wave that sets the initial reference voltage. A reference voltage indicating a peak voltage up to n waves is stored.

  The reference voltage calculation means 18 outputs a storage completion signal when the required number of reference voltages are stored in the reference voltage storage means 17, and when the storage completion signal is detected, the reference voltage calculation means 18 and the peak value Pn of the last n-th wave are one before. The position to be set between the peak value Pn-1 of the (n-1) th wave is determined by calculation.

  For example, the final reference voltage value = Pn−1 + (Pn−Pn−1) × s (s: setting ratio) is obtained, and the obtained reference voltage value is output to the reference voltage setting means 13. Thereafter, when the flow rate is measured, the reference voltage of the final calculated value is set in the reference voltage comparison means 6 and an ultrasonic signal is received. When the final reference set value has been set, the measurement control unit 14 determines that the reference voltage adjustment has been completed. The set ratio S is a value determined in advance under conditions such as the type of gas and the actual machine.

The reference voltage setting unit 13 sets a reference voltage for each predetermined period, and the propagation time measured and obtained by the propagation time measuring unit 15 is converted into an instantaneous flow rate value by the flow rate calculating unit 20.

  The abnormality determination means 21 processes the obtained instantaneous flow rate, average flow rate, etc., and monitors the abnormalities of the equipment used. The abnormality determination means 21 stores a time limit value for use time corresponding to each flow rate region, a monitor determination value for the maximum use flow rate, or the like. For example, when a hose that supplies gas to a stove or the like is disconnected for some reason, an abnormally large flow rate is generated, but the total flow cutoff value for monitoring such a state and the maximum usage time for normal use of the instrument The usage time cutoff time limit that defines the usage time limit time corresponding to the case of use for a much longer time is stored. By comparing and determining the set value and the average flow rate value by the abnormality determination unit 21, the flow rate value does not exceed the maximum use flow rate value, or the use time of the appliance is set to the time limit for continuous use corresponding to the registered flow rate. Monitor whether it has exceeded.

  When the abnormality determining means 21 determines that an abnormality has been established, a cutoff signal is sent to the cutoff means 22 to stop the gas supply. In addition, the notification communication means 23 displays the shut-off state and the shut-off content on a liquid crystal display element or the like, and notifies the center of the gas company that is monitoring the safety of the gas by communication such as a telephone line.

  Next, the operation of the gas shut-off device configured as described above will be described.

  When starting the gas flow rate measurement, a reference voltage adjustment start instruction is received through the measurement control unit 14 through, for example, a switch called a test switch or a communication setting unit. Normally, when a signal is received from the measurement control means 14 through preparation, ultrasonic signal level adjustment is started. For example, when the upstream transmitter / receiver 1 receives a drive signal from the transmitter 4, the ultrasonic wave propagates through the flow path and reaches the downstream transmitter / receiver 2. The ultrasonic signal that has reached the downstream transceiver 2 is amplified to a predetermined level by the amplifying means 5 and adjusted so that the maximum wave of the received wave becomes a constant level, and then the process proceeds to reference voltage adjustment.

  In the reference voltage adjustment, first, the reference voltage is set to the received wave above the first wave of the received ultrasonic wave. As a result, even when the reverberation vibration of the ultrasonic wave is added to the received signal and the vibration exceeding the worst first wave is received without being attenuated, it is not necessary to detect the first wave, and a reference voltage exceeding the reference voltage is set. is doing. A reference voltage is set for the nth wave (midway wave) in the middle of the growing reception wave.

  For example, when the wave of the reception wave used as a reference for measuring the propagation time used for the flow rate calculation is the third wave, the first wave and the second wave are set as values that can detect the previous second wave. The intermediate value of the peak voltage is set to the initial value of the reference voltage.

  Next, the peak of the halfway wave is searched. When the received wave set with the reference voltage is detected by the reference voltage comparing means 6, the propagation time until the zero cross of the wave is measured by the propagation time measuring means 15. The propagation time difference comparison means 16 stores the previously measured propagation time, and obtains the propagation time difference from the currently measured propagation time. For the same halfway wave, the propagation time is almost the same and the difference is zero. When there is no propagation time difference, no completion signal is received from the reference voltage calculation means 18, so the reference voltage setting means 13 increases the reference voltage by about 1 tap (several mV). In this way, the reference voltage is gradually increased, and when the peak of the intermediate wave is exceeded, the propagation time difference comparison means 16 determines that the propagation time difference is equal to or greater than a predetermined time, and determines that the peak of the intermediate wave has been exceeded. The reference voltage thus stored is stored in the reference voltage storage means 17. The reference voltage is set to the next wave (n + 1 wave) after the halfway wave. Similarly, the reference voltage is increased and the peak value is searched. When the propagation time difference comparison unit 16 detects a predetermined time or longer again, the reference voltage storage unit 17 stores the reference voltage set at that time, assuming that the peak of the (n + 1) th wave is detected.

In this way, the reference voltage, that is, the peak voltage of each wave is sequentially stored, and when the number of stored reference voltages reaches a predetermined number, a storage completion signal is sent from the reference voltage storage means 17 to the reference voltage calculation means. 18 is output.

  That is, in the reference voltage storage means 17, when the predetermined number is two, the peak voltage of the intermediate wave (nth wave) and the peak voltage of the next wave (n + 1 wave), and when the predetermined number is three, the intermediate wave The peak voltages of the (n-th wave), the next wave (n + 1-th wave), and the next wave (n-th + 2nd wave) are stored. The reference voltage calculation means 18 multiplies the voltage difference between the peak voltage of the last wave and the peak voltage of the previous wave by the set ratio therebetween, and outputs the set reference voltage to the reference voltage setting means 13 as the adjustment completed. To do. This eliminates the need to detect the first wave, so that an optimum reference voltage can be searched and set in a short time.

  As shown in FIG. 3, the propagation time can be accurately measured if the propagation time can be accurately measured except for the minimum wave, and if the wave near the zero cross is relatively standing. Therefore, the final reference voltage setting value used at the time of measurement can be easily set in a short time by measuring the peak value of the wave and the previous wave.

  Next, the reference voltage is adjusted and the setting is completed by the reference voltage setting unit 13, and the instantaneous flow rate is calculated by the flow rate calculation unit 20 from the upstream propagation time and the downstream propagation time measured by the propagation time measurement unit 15. The abnormality determination means 21 obtains an average flow rate value for every predetermined number of instantaneous flow rates obtained by the flow rate calculation means 20. The abnormality determination means 21 stores a time limit value for use time corresponding to each flow rate region, a monitor determination value for the maximum use flow rate, or the like.

  For example, when a hose that supplies gas to a stove or the like is disconnected for some reason, an abnormally large flow rate is generated, but the total flow cutoff value for monitoring such a state and the maximum usage time for normal use of the instrument The usage time cutoff time limit that defines the usage time limit time corresponding to the case of use for a much longer time is stored. By comparing and determining the set value and the average flow rate value by the abnormality determination unit 21, the flow rate value does not exceed the maximum use flow rate value, or the use time of the appliance is set to the time limit for continuous use corresponding to the registered flow rate. Whether or not it has been exceeded is monitored, and if it is exceeded, a cutoff signal is sent to the cutoff means 22 to stop the gas supply.

  The notification communication means 23 displays the cutoff state and the cutoff content on a liquid crystal display element (not shown) or the like, and notifies the center of the gas company that is monitoring the safety of the gas by communication such as a telephone line. The gas company that has received the report can immediately take countermeasures such as replacing the gas shut-off device, and can quickly avoid abnormal conditions.

  As described above, when the reference voltage is set as an adjustment for measuring the flow rate, when the output of the amplifying unit 5 is superimposed on the received signal without any attenuation such as a reverberant signal, the search is performed from the 0 level of the received wave. Rather than searching, find the peak value from the midway wave to the wave you want to set, and find the reference voltage at the time of measurement from the peak value of the wave you want to set and the previous peak value. The reverberation signal must be detected as the first wave, but the first wave cannot be detected, and another wave is mistakenly detected as the first wave and is different from the wave originally intended to be set. It is possible to prevent the reception wave from being set, and the effect is extremely high.

  As described above, the gas cutoff device according to the present invention can be accurately set without being affected by reverberation or noise when setting the reference voltage for detecting the ultrasonic signal, and similarly, a flow rate measuring device such as a water meter. Applicable in general.

1 Upstream transmitter / receiver (transmitter / receiver)
2 Downstream transmitter / receiver (transmitter / receiver)
3 switching means 4 transmitting means 5 amplifying means 6 reference voltage comparing means 13 reference voltage setting means 14 measurement control means 15 propagation time measuring means 16 propagation time difference comparing means 17 reference voltage storage means 18 reference voltage calculating means 20 flow rate calculating means 21 abnormality determination Means 22 Blocking means

Claims (2)

A pair of transceivers for transmitting and receiving ultrasound signals;
Switching means for switching one of the pair of transceivers to the receiving side and the other to the transmitting side;
A transmission means for outputting a transmission signal to the transceiver set on the transmission side by the switching means;
Amplifying means for amplifying the ultrasonic signal received by the transceiver set on the receiving side by the switching means;
A reference voltage comparison means for detecting a received wave by comparing the ultrasonic signal amplified by the amplification means with a reference voltage;
Reference voltage setting means for adjusting and setting the reference voltage;
A propagation time measuring means for measuring a propagation time of an ultrasonic signal between the pair of transceivers when detecting a predetermined wave of the received wave by the reference voltage comparing means;
A flow rate calculating means for calculating an instantaneous flow rate value from the propagation time measured by the propagation time measuring means, an abnormality determining means for determining the presence or absence of an abnormality from the flow rate obtained by the flow rate calculating means,
A shut-off means for shutting off the gas supply when the abnormality judgment is established by the abnormality judging means,
The reference voltage setting means has an initial value of the reference voltage larger than the peak voltage of the first wave at the time of adjustment, and an nth wave (n is 3 or more) serving as a reference for measuring the propagation time used in the flow rate calculation means The propagation time measured this time by the propagation time measuring means and the previous measurement were made while gradually increasing this reference voltage while setting the value to be smaller than the peak voltage of the (n-1) th wave before the integer). The reference voltages at the time when the time difference from the propagation time becomes equal to or greater than a predetermined value are sequentially stored. The plurality of stored reference voltages are regarded as the peak voltage of each wave of the received wave, and the (n−1) -th wave and the n-th wave. A gas cutoff device that sets a reference voltage for detecting the nth wave from the peak voltage of the wave. A program for causing a computer to function as all or part of means of the gas shut-off device according to claim 1.