JP5847628B2 - Gas shut-off device - Google Patents

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, there has been a gas shut-off device of this type as shown in FIG. 5 (see, for example, Patent Document 1).

  The configuration of the gas cutoff device of Patent Document 1 will be briefly described with reference to FIG. In FIG. 5, a first ultrasonic transducer 2 that transmits ultrasonic waves and a second ultrasonic transducer 3 that receives ultrasonic waves are arranged in the flow direction 1 at an angle θ in the flow direction. 5 is a transmission means to the first ultrasonic transducer 2, 4 is a switching means for switching between transmission and reception of the first ultrasonic transducer 2 and the second ultrasonic transducer 3, and 6 is an ultrasonic transducer on the receiving side. Amplifying means 7 amplifies the received signal, and 7 is a signal blocking means for passing and blocking the received signal of the ultrasonic transducer on the receiving side. The signal that has passed through the signal blocking means 7 is compared with the reference voltage by the comparison means 8, and is output to the repetition means 9 as a zero cross detection signal at the next zero cross point where the magnitude relationship is inverted.

  The repeater 9 counts the reception of the zero cross detection signal from the comparator 8, counts the preset number of times, and outputs the signal from the comparator 8 to the controller 12. Reference numeral 10 denotes a first timing unit that counts the time counted in advance by the repetition unit 9, and 11 denotes a pipe size and a flow state according to the time counted by the first timing unit 10. The flow rate calculating means for calculating the flow rate. 13a is a second time measuring means for measuring a preset time by receiving a signal from the control means 12, 13b is a third time measuring means for measuring the time difference between the signals of the comparing means 8 and the second time measuring means 13a, and 13c. Is a fourth timing means for receiving the signal of the second timing means 13a and re-counting the time counted by the third timing means 13b, and the second timing means 13a, the third timing means 13b, and the fourth timing means 13c A blocking control means 13 for controlling the blocking means is configured. A control unit 12 receives signals from the flow rate calculation unit 11 and the repetition unit 9 and controls operations of the transmission unit 5 and the cutoff control unit 13.

  Next, the operation of the configuration of the conventional gas cutoff device will be described.

  First, when the flow rate measurement is started, the control unit 12 operates the transmission unit 5 to transmit an ultrasonic signal from the ultrasonic transducer 2 and outputs a time measurement start signal to the second time measurement unit 13a. The second time measuring means 13a starts measuring time in response to the time measuring start signal, measures two preset times (constant times t0 and t1 in FIG. 6), and ends each time measurement (points A and B in FIG. 6). Then, a timing start signal is output to the fourth timing means 13c and the third timing means 13b.

  The third time measuring means 13b measures the time Ct1 from the time measurement start signal from the second time measuring means 13a (point B in FIG. 6) to the input of the signal from the comparison means 8 (point C in FIG. 6), After the time is measured, the time Ct1 is transferred to the fourth time measuring means 13c.

  The fourth timing means 13c starts timing from the timing start signal (point A in FIG. 6) from the second timing means 13a and cuts off the signal at a time point (point D in FIG. 6) that has been measured for a preset time Ct0. The signal is output to the means 7, and the signal blocking means 7 is switched from the blocking state to the passing state, and is returned to the blocking state after a predetermined time has elapsed.

  On the other hand, the ultrasonic signal transmitted from the first ultrasonic transducer 2 propagates through the flow path 1, is received by the second ultrasonic transducer 3, is amplified by the amplification means 6, and is sent to the signal blocking means 7. Entered. When the signal blocking means 7 is switched from the blocking state to the passing state by the blocking control means 13 as described above, the received signal of the second ultrasonic transducer 3 amplified by the amplifying means 6 is input to the comparing means 8, and the reference voltage And is repeatedly output to the means 9 as a zero cross detection signal at the next zero cross point where the magnitude relationship is inverted. The zero cross detection signal is counted by the repeating means 9 and then input to the control means 12.

  Then, the control unit 12 operates the transmission unit 5 again to transmit the ultrasonic signal from the ultrasonic transducer 2 and outputs the time measurement start signal to the second time measurement unit 13a again. Accordingly, in FIG. 6, from the point C of the zero-crossing detection signal of the comparison means 8, the second time measuring means 13a starts counting the fixed times t0 and t1 again, and the fourth time measuring means at the points A 'and B' in FIG. A timing start signal is output to 13c and the third timing means 13b. The fourth time measuring means 13c measures the time Ct1 transferred from the third time measuring means 13b, and the third time measuring means 13b measures the time Ct2 until the signal of the comparison means 8 (point C 'in FIG. 6) is input. To do.

  That is, the 4th time measuring means 13c time-measures the time which the 3rd time measuring means 13b of the last operation | movement measured. Such an operation is repeated n times set in advance, and the time between them is measured by the time measuring means 10. Then, the first ultrasonic transducer 2 and the second ultrasonic transducer 3 are switched by the switching unit 4, the above-described operation is performed, and the time at that time is measured by the time measuring unit 10.

  Then, the flow rate value is obtained by the flow rate calculation means 11 from these two time differences in consideration of the size of the flow path and the flow state. The timing at which the signal blocking means 7 is switched from the blocking state to the passing state by operating as described above is determined based on the time counted by the third time counting means 13b one time before the repeated operation, and the value is compared with the comparing means 8 The time is shorter by the time difference (t1−t0) between the times t0 and t1 measured by the second timing means 13a than the zero cross detection signal.

  That is, if the zero cross detection signal of the comparison means 8 is output at the same timing as the previous time (the output of the dotted comparison means 8 in FIG. 6), the signal cut-off means 7 is cut off before the time t1-t0 of the output. Switch to the passing state. The timing of the zero-crossing detection signal of the comparison means 8 fluctuates due to the flow rate change of the fluid pipe line and the flow rate change due to the temperature. However, the repeated operation interval during the repeated operation is usually a short time of several hundred μs. The flow rate change and the temperature change are small, and the output fluctuation t2 of the comparison means 8 is also small. Therefore, the timing of the zero cross detection signal hardly fluctuates.

  Here, if the time difference between the times t0 and t1 timed by the second time measuring means 13a is set to a value slightly larger than the maximum change width of the output fluctuation t2 of the comparing means 8, the signal cutoff means 7 is cut off before the reception signal arrives. The period from the reception signal waiting state of the comparison means 8 to the arrival of the reception signal can be set to a short time, the period affected by noise is shortened, and the influence of noise is reduced. .

Japanese Patent No. 3473591

  However, when the gas shut-off device having the above-mentioned conventional configuration is installed in the market or after it is installed, the gas consumer can replace the water heater with a new large combustion amount when moving in, or newly install new equipment. When it is necessary to remove the air in the gas pipe, it is necessary to replace it with the used gas. At that time, the gas is replaced with the original gas using a small flow rate device such as a gas table installed in each customer's house. However, because of the small flow rate, it takes a long time to replace the gas in the pipe.

  During this gas replacement, the ultrasonic measuring unit of the gas shut-off device is in a mixed state for a long time with air or a used gas (for example, 13A city gas). At this time, the ultrasonic signal is a slow medium (air) with a different propagation speed of the medium. The propagation time may vary depending on the state of the medium for each measurement, such as passing through a fast medium (for example, city gas such as 13A) or measuring a slow air state from a city gas having a fast propagation speed.

  Therefore, when the measurement is suddenly performed from a medium with a long propagation time to a medium with a short propagation time, the medium is suddenly changed because the signal blocking means is determined based on the long propagation time of the third time measuring means measured immediately before. When the gas has a high propagation speed, the ultrasonic signal has reached, but the signal cutoff means is still in the cutoff state, so the propagation time cannot be measured, and as a result, the correct flow rate cannot be measured (for example, every measurement is positive) There is a problem that a negative flow rate fluctuation occurs, various safety judgments are made with an abnormal flow rate value, erroneous blockage occurs, or abnormal integration is erroneously performed.

  The present invention solves the above-described problem, and provides a highly reliable and easy-to-use gas shut-off device that does not cause false shut-off and mis-integration even if a mixed state with different gases occurs in a gas flow path. .

  In order to solve the above-described conventional problems, a gas cutoff device of the present invention is arranged along a flow of a flow path, and a pair of transceivers for transmitting and receiving an ultrasonic signal, and switching for switching between transmission and reception of the pair of transceivers Means, transmission means for driving the transceiver set on the transmission side by the switching means, reception means for receiving an ultrasonic signal from the transceiver set on the reception side by the switching means, and the reception Driven by the signal detection control means for controlling the detection start time of the reception signal from the means, the amplitude determination means for judging whether or not the reception signal from the reception means is at a predetermined ultrasonic signal level, and the transmission means Propagation time measuring means for measuring the time until the signal is detected by the amplitude determining means, flow rate calculating means for calculating an instantaneous flow rate from the measurement value of the propagation time measuring means, and instantaneous flow rate obtained by the flow rate calculating means A signal for determining a correction time for advancing the signal detection start time of the signal detection control means when the flow rate change determination means determines that there is a flow fluctuation. An average flow rate is calculated from a detection calculation unit, a time measurement unit that counts time based on a calculation result of the signal detection calculation unit, and outputs a signal detection start signal to the signal detection control unit, and an instantaneous flow rate obtained by the flow rate calculation unit. An average flow rate calculating means to be obtained; an abnormality determining means for determining presence / absence of an abnormality from the average flow rate calculated by the average flow rate calculating means; and a blocking means for cutting off gas supply when the abnormality determination is established by the abnormality determining means. It is provided.

  And when the gas shut-off device is installed or when the gas pipe work is in a mixed state with the air or the original supply gas in the gas pipe or the gas shut-off device, the measured flow rate exceeds the predetermined value. When the presence or absence of flow rate change is monitored and positive or negative flow rate fluctuations greater than or equal to a predetermined value are detected, the signal detection calculation means obtains a time during which the propagation time of all the mixed media can be detected, and the signal detection control means promptly Since signal detection is started, the flow rate can be obtained from the normally received ultrasonic signal, the erroneous determination due to the abnormal flow rate due to the occurrence of the mixed state in the gas supply pipe can be avoided, and there is a problem of erroneous interruption It is highly reliable and can be safely monitored.

  The gas shut-off device of the present invention has a flow measuring unit of the gas shut-off device for a long time when purging the air in the gas pipe at the time of installation, particularly when performing gas replacement using a small combustion amount instrument held by a gas consumer. Although the mixed state with the medium other than the original gas used continues for a long time, when the detection is started, that is, when the flow rate fluctuation state is detected, the signal detection control means can detect both together with the propagation time of the medium before and after the replacement. The signal detection start control is performed at an early stage, and after a predetermined period (predetermined number of times) when the flow rate fluctuation has subsided and the original supply gas has been replaced, the time is switched to the signal detection control time before receiving the noise signal for noise suppression. Since the flow rate value is abnormal depending on the condition and the measurement control that is not affected by noise is performed in the normal condition after the mixed condition is resolved, the instrument abnormality can be monitored and integrated normally, and erroneous shut-off and error accumulation are performed. It is possible to prevent.

Control block diagram of gas shutoff device in embodiment 1 of the present invention Control block diagram of gas cutoff device in embodiment 2 Control block diagram of gas cutoff device in embodiment 3 Control block diagram of gas cutoff device in embodiment 4 Control block diagram of a conventional gas shut-off device Operation explanatory diagram of a conventional gas shut-off device

  1st invention is set along the flow of a flow path, and is set to the transmission side by a pair of transmitter / receiver which transmits / receives an ultrasonic signal, the switching means which switches transmission / reception of a pair of said transmitter / receiver, and the said switching means. The transmission means for driving the transceiver, the reception means for receiving the ultrasonic signal from the transceiver set on the reception side by the switching means, and the time for starting detection of the reception signal from the reception means are controlled. Signal detection control means, amplitude determination means for determining whether or not the received signal from the reception means is at a predetermined ultrasonic signal level, and drive from the transmission means until signal detection by the amplitude determination means Propagation time measuring means for measuring time, flow rate calculating means for calculating an instantaneous flow rate from the measurement value of the propagation time measuring means, and determining whether or not there is a flow fluctuation more than a predetermined value from the instantaneous flow rate obtained by the flow rate calculating means Flow A change determination means, a signal detection calculation means for determining a correction time for advancing the signal detection start time of the signal detection control means when the flow rate change determination means determines that there is a flow fluctuation, and a calculation result of the signal detection calculation means A time measurement unit that counts time based on the output signal and outputs a signal detection start signal to the signal detection control unit, an average flow rate calculation unit that calculates an average flow rate from an instantaneous flow rate that is calculated by the flow rate calculation unit, and an average flow rate calculation unit An abnormality determination unit that determines whether there is an abnormality from the obtained average flow rate, and a blocking unit that blocks gas supply when the abnormality determination is established by the abnormality determination unit.

  According to the above invention, when the gas shut-off device is installed or when the gas pipe construction is performed, the flow measuring unit of the gas pipe or the gas shut-off device is in a mixed state with air or the original supply gas. The flow rate may fluctuate abnormally greatly. If the flow rate reaches a predetermined value or more, or if the flow rate changes to the minus side and a flow rate that exceeds the predetermined value is detected, all of the mixed media are detected by the signal detection calculation means. The signal detection start time is obtained with a correction value that can detect the propagation time, and the signal detection control means controls the start of signal detection at an early stage, so the propagation time suddenly becomes faster or shorter depending on the medium type, for example, due to the mixed state. In addition, the flow rate can be obtained from the ultrasonic signal that is normally received, the erroneous determination due to the abnormal flow rate caused by the mixed state in the gas supply pipe can be avoided, and the erroneous shut-off No, reliable, can be performed safely security monitoring without the gas company is unnecessary dispatch due erroneous cutoff.

  A second invention is set on the transmission side by a pair of transmitters / receivers that are arranged along the flow of the flow path and that transmits / receives ultrasonic signals, a switching unit that switches transmission / reception of the pair of transmitters / receivers, and the switching unit. The transmission means for driving the transceiver, the reception means for receiving the ultrasonic signal from the transceiver set on the reception side by the switching means, and the time for starting detection of the reception signal from the reception means are controlled. Signal detection control means, amplitude determination means for determining whether or not the received signal from the reception means is at a predetermined ultrasonic signal level, and drive from the transmission means until signal detection by the amplitude determination means Propagation time measuring means for measuring time, flow rate calculating means for calculating an instantaneous flow rate from the measurement value of the propagation time measuring means, and determining whether or not there is a flow fluctuation more than a predetermined value from the instantaneous flow rate obtained by the flow rate calculating means Flow From the results of the change determination means, the signal detection initial correction means for returning the signal detection start time of the signal detection control means to the initial set value when the flow rate change determination means determines that there is a flow fluctuation, and the signal detection initial correction means Time measurement means for counting time and outputting a signal detection start signal to the signal detection control means, average flow calculation means for obtaining an average flow rate from the instantaneous flow rate obtained by the flow rate calculation means, and average obtained by the average flow rate calculation means An abnormality determination unit that determines presence / absence of abnormality from the flow rate, and a blocking unit that blocks supply of gas when abnormality determination is established by the abnormality determination unit.

  According to the above invention, when the gas shut-off device is installed or when the gas pipe construction is performed, the flow measuring unit of the gas pipe or the gas shut-off device is in a mixed state with air or the original supply gas. When the flow rate change over a predetermined value is monitored by the flow rate, and the flow rate fluctuation over the predetermined value is detected, the signal detection initial correction means can detect the initial value, that is, the initial value that can detect all the propagation time including the medium other than the gas used Since the signal detection control means controls the signal detection start in a short period of time, it is possible to reliably detect the ultrasonic signal regardless of the mixed state, so that the flow rate can be obtained accurately, and due to the occurrence of the mixed state in the gas supply pipe It is possible to avoid misjudgment due to abnormal flow rate, and there is no problem of erroneous shut-off, high reliability, and safe maintenance without unnecessary dispatch by the gas company due to false shut-off etc. Perform the view.

  According to a third aspect of the present invention, a pair of transmitters / receivers that are arranged along the flow of the flow path and that transmits / receives an ultrasonic signal, a switching unit that switches transmission / reception of the pair of transmitters / receivers, and the switching unit are set on the transmission side The transmission means for driving the transceiver, the reception means for receiving the ultrasonic signal from the transceiver set on the reception side by the switching means, and the time for starting detection of the reception signal from the reception means are controlled. Signal detection control means, amplitude determination means for determining whether or not the received signal from the reception means is at a predetermined ultrasonic signal level, and drive from the transmission means until signal detection by the amplitude determination means A flow time measuring means for measuring time, a flow rate calculating means for calculating an instantaneous flow rate from a measurement value of the propagation time measuring means, and a flow rate determination for performing a flow rate output when a flow rate of a predetermined value or more is detected by the flow rate calculating means. And a signal detection calculation means for obtaining a correction time for advancing the signal detection start time of the signal detection control means upon detection of a flow rate presence state by the flow rate determination means, and a time based on the calculation result of the signal detection calculation means And a time measurement means for outputting a signal detection start signal to the signal detection control means, an average flow rate calculation means for obtaining an average flow rate from an instantaneous flow rate obtained by the flow rate calculation means, and an average obtained by the average flow rate calculation means An abnormality determination unit that determines presence / absence of abnormality from the flow rate, and a blocking unit that blocks supply of gas when abnormality determination is established by the abnormality determination unit.

  According to the above invention, when the gas shut-off device is installed or when the gas pipe construction is performed, the flow measuring unit of the gas pipe or the gas shut-off device is in a mixed state with air or the original supply gas. If there is a flow rate change of more than a predetermined value depending on the flow rate, and only the flow rate fluctuation less than the predetermined value is detected, if the flow rate determination means establishes the flow rate, all the media that are mixed by the signal detection calculation means The signal detection start time is obtained by a correction value that can detect the propagation time of the signal, and the signal detection control means controls the signal detection start at an early stage.For example, the propagation time may suddenly become faster or shorter depending on the medium type. The flow rate can be obtained from the ultrasonic signal that is normally received, the erroneous determination due to the abnormal flow rate due to the mixed state occurrence in the gas supply pipe can be avoided, and if the error is interrupted Cormorant problem is not, high reliability, can be performed safely security surveillance without gas operators to unnecessary spending due to incorrect cut-off.

  4th invention is arrange | positioned along the flow in a flow path, a pair of transmitter / receiver which transmits / receives an ultrasonic signal, the switching means which switches transmission / reception of a pair of said transmitter / receiver, and sets to the transmission side by the said switching means Transmitting means for driving the transmitted / received transmitter, receiving means for receiving the ultrasonic signal from the transceiver set on the receiving side by the switching means, and time for starting detection of the received signal from the receiving means Signal detection control means for controlling the signal, amplitude determination means for determining whether or not the received signal from the reception means is at a predetermined ultrasonic signal level, driving by the transmission means, and signal detection by the amplitude determination means A flow time measurement means for measuring a time until a flow rate, a flow rate calculation means for calculating an instantaneous flow rate from a measured value of the propagation time measurement means, and a flow rate with an output when a flow rate of a predetermined value or more is detected by the flow rate calculation means When a flow rate presence state is detected by the determination unit and the flow rate determination unit, the signal detection initial correction unit which returns the signal detection time of the signal detection control unit to an initial set value, and the time is counted from the output of the signal detection initial correction unit. A time measuring means for outputting a signal detection start signal to the signal detection control means, an average flow rate calculating means for obtaining an average flow rate from an instantaneous flow rate obtained by the flow rate calculating means, and an abnormality from the average flow rate obtained by the average flow rate calculating means An abnormality determining means for determining the presence or absence of gas and a blocking means for blocking the supply of gas when the abnormality determination is established by the abnormality determining means.

  According to the above invention, when the gas shut-off device is installed or when the gas pipe construction is performed, the flow measuring unit of the gas pipe or the gas shut-off device is in a mixed state with air or the original supply gas. If the flow rate is detected by the flow rate determining means when the flow rate change of less than the predetermined value is detected and the flow rate is determined to be established, it is determined that the flow rate measurement unit may be in a mixed state Then, in order to enable the signal detection control means to detect the signal at the initial value time, the signal detection control means is changed to the initial value time that can detect the propagation time including all the mixed media by the signal of the display flow rate determination means and the signal detection control means at an early stage. Therefore, even if the propagation time suddenly increases or decreases depending on the medium type, the flow rate can be obtained from the normally received ultrasonic signal, It is possible to avoid misjudgment due to abnormal flow rate due to mixed state occurrence, and there is no malfunction of erroneous shutoff, high reliability, and safety monitoring can be performed safely without causing gas operators to unnecessarily dispatch due to false shutoff etc. Yes.

  A fifth invention is a program for causing a computer to execute all or part of the means of the shut-off device according to any one of the first to fourth inventions.

  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 control block diagram of the gas shutoff device according to Embodiment 1 of the present invention. The same number is attached | subjected to the equivalent to FIG.

  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. The flow path is connected to a supply port for supplying gas to each gas appliance through the inlet side flow path from the inlet of the gas shut-off device, through the flow path at the bottom, and through the outlet side flow path.

  FIG. 1 is a control block diagram of the gas cutoff device. A pair of transmitters / receivers (upstream transmitter / receiver 16 and downstream transmitter / receiver 17) for transmitting and receiving an ultrasonic signal are attached facing the flow direction of the flow path in the gas cutoff device. Then, the intermittent control means 14 drives the flow rate detection means 15 every few seconds (for example, every 2 seconds), and periodically measures the flow rate.

  The flow rate detection means 15 includes an upstream transceiver 16, a downstream transceiver 17, a switching means 18, a transmission means 19, a reception means 20, a signal detection control means 22, an initial setting means 21, an amplitude determination means 23, a propagation time measurement means. 24, signal detection calculation means 27, and time measurement means 28. The upstream side transceiver 16 and the downstream side transceiver 17 that transmit or receive ultrasonic waves can be switched between transmission and reception by a switching means 18.

  The upstream transmission / reception device 16 or the downstream transmission / reception device 17 is connected to transmission means 19 for outputting an ultrasonic signal, and the switching device 18 transmits the ultrasonic signal via the upstream transmission / reception device 16 or the downstream transmission / reception device 17. Received by the receiving means 20.

  Here, when transmission of the ultrasonic signal is started by the upstream side transmitter / receiver 16 by the transmission unit 19, the time measurement starts by the propagation time measuring unit 24 and is received by the downstream side transmitter / receiver 17 after propagating in the flow path. The signal detection control means 22 blocks the detection of the ultrasonic signal until the time set by the initial setting means 21.

  This initial setting means 21 sets the time for which the detection of the ultrasonic signal is cut off to a short control time so as to enable measurement assuming not only air and gas types originally used but also all gas types. . On the other hand, the signal detection control means 22 controls the detection start time with the initial set value until the first propagation time is obtained. After the time set by the initial setting means 21 has elapsed, the signal detection control means 22 enters a detection start state, and the received ultrasonic signal passes through the signal detection control means 22 and is input to the amplitude determination means 23. When the amplitude determination means 23 determines whether the amplitude is equal to or greater than a predetermined level and detects an ultrasonic signal of a predetermined level or higher, the propagation time measurement means 24 completes the time until the detection signal (propagation time downstream). Ask.

  Next, transmission / reception is switched by the switching means 18 and similarly an ultrasonic signal is transmitted from the downstream to the upstream, and the propagation time to the downstream side is obtained in the same manner as the propagation time to the downstream side.

  The above operation is repeated a predetermined number of times by the intermittent control means 14, and the upstream and downstream propagation times are measured. The signal detection control means 22 returns to the signal cutoff state after a predetermined time has elapsed. Then, the propagation time measured by the intermittent control means 14 and obtained by the propagation time measurement means 24 is converted into an instantaneous flow rate by the flow rate calculation means 25.

  The instantaneous flow rate obtained by the flow rate calculation means 25 is determined by the flow rate change determination means 26 for the presence or absence of flow rate fluctuations greater than a predetermined value. When there is no flow rate fluctuation more than a predetermined value, the signal detection calculation means 27 obtains the signal detection start time from the obtained upstream propagation time, the propagation time shorter than the downstream propagation time, and the preset first signal detection correction value. . The first signal detection correction value is about several μs, and is a correction value for starting control of the signal detection control means 22 before the amplitude determination means 23 detects a signal so as not to erroneously detect noise.

  The time obtained by the signal detection calculating means 27 is counted by the time measuring means 28, and when this time has elapsed, the signal detection control means 22 outputs a signal for controlling the detection start. Once the propagation time is obtained, the detection start time of the signal detection control means 22 is set based on the propagation time at the previous measurement.

  After the gas shut-off device is installed, the air in the gas pipe is replaced with the equipment of the gas consumer. However, when a small flow rate equipment such as a gas table is used, a considerable time is required for the gas replacement. During this time, the flow rate measurement unit of the gas shut-off device is in a mixed gas state with air or supply gas (for example, city gas 13A), and the instantaneous flow rate value measured in the mixed gas state fluctuates greatly, and the positive and negative fluctuation flow rates And continue for a long time.

  When the flow rate change determining means 26 detects a flow rate that is equal to or higher than a predetermined flow rate due to a change in the instantaneous flow rate, the flow rate change determining means 26 determines a mixed gas state with a different gas and outputs a fluctuation detection signal to the signal detection calculating means 27. In this case, the instantaneous flow rate may be positive or negative. The signal detection calculation unit 27 obtains the signal detection start time in the mixed gas state from the propagation time of the previous measurement and the preset second signal detection correction value. This second signal detection correction value is a value that can measure the propagation time in the originally used gas (the propagation speed in the medium is fast) or in a medium with a slow propagation speed.

  At the time of detecting the flow fluctuation due to the mixed state, the obtained signal detection start time is output to the time measuring means 28 and counted. The signal cut-off time of the signal detection control means 22 is controlled to be short, and the original ultrasonic signal is surely detected regardless of what medium is in the mixed state to determine the propagation time.

  On the other hand, the instantaneous flow rate value obtained by the flow rate calculation unit 25 is input to the average flow rate calculation unit 29, and a predetermined number of instantaneous flow rate values are collected and calculated as an average flow rate value. The obtained average flow rate value is output to the abnormality determining means 30.

  Then, the abnormality determination means 30 performs time monitoring of the used appliance at the obtained average flow rate, or monitors whether there is an abnormality than the currently used flow rate of the used appliance. The abnormality determination means 30 stores an initial value such as a time limit value for use time corresponding to each flow rate region or a monitor determination value for the maximum use flow rate. For example, when the 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 condition and the maximum use time of the appliance normally 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 30, the flow rate value does not exceed the maximum use flow rate value, or the use time of the appliance is set to the continuous use time limit corresponding to the registered flow rate. Monitor whether it has exceeded. When the abnormality determination means 30 determines that an abnormality is established, a cutoff signal is sent to the cutoff means 31 to stop the gas supply. Further, the instantaneous flow rate obtained by the flow rate calculation means 25 is integrated as a use amount by the integration means 32. The notification communication means 33 displays the cutoff state, the cutoff content, and the integrated value 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. The gas shut-off device is installed in a newly built house, or a new large-sized device is installed or replaced. Replace the air in the piping with the supply gas. At this time, a small flow rate instrument such as a gas table may be used. When the pipe length from the gas shut-off device to the gas instrument is long like a detached house, it takes a long time to replace the gas.

  When flow measurement is performed under such conditions in the pipe, the following phenomenon may occur. Over time, in the flow path, different gases such as supply gas and air are mixed due to convection and the like, and the vicinity of the upstream transmitter / receiver 16 and the downstream transmitter / receiver 17 in the gas shutoff device also takes longer time. It becomes a mixed state. The ultrasonic wave transmitted by the upstream side transceiver 16 or the downstream side transceiver 17 propagates in the mixed gas, and propagates in the gas having a fast propagation time every time measured by the intermittent control means 14. If so, the case of propagating in the air with a slow propagation time occurs discontinuously.

  When the inside of the gas pipe is only air, the propagation time is slower and the propagation time is measured by the propagation time measuring means 24 as compared with the original supply gas (for example, city gas such as 13A). The flow rate detecting means 15 is periodically driven by the intermittent control means 14. First, the upstream transceiver 16 is driven by the transmission means 19 and is received by the downstream transceiver. The receiving means 20 amplifies the received signal and outputs it to the signal detection control means 22. The signal detection control unit 22 stops signal detection until the time obtained by the signal detection calculation unit 27 elapses. Since the initial time is set until the first upstream / downstream propagation time is obtained, the signal detection stop is released early. When the next measurement time elapses, the signal detection stop time is shorter than the propagation time. When the time measuring unit 28 counts up, the signal detection control unit 22 starts detection, and outputs an ultrasonic signal received thereafter to the amplitude determination unit 23. The amplitude determination means 23 determines whether the ultrasonic signal has an amplitude grown above a predetermined level. When an ultrasonic signal having an amplitude of a predetermined level or more is detected, it is determined that reception is completed, and a completion notification is sent to the propagation time measuring means 24. For the obtained propagation time, the flow rate calculation means 25 determines the instantaneous flow rate.

  Even if the replacement is started, if the gas shut-off device is only air, the instantaneous flow rate obtained by the flow rate calculation unit 25 is monitored by the flow rate change determination unit 26, and a stable flow rate state is obtained. The signal detection calculation means 27 obtains the signal detection start time from the propagation time in the air medium and the first signal detection correction value. The obtained time is counted by the time measuring means 28, and when it has elapsed, a detection start signal is output to the signal detection control means 22. When the signal detection control means 22 receives the signal detection start, the signal detection control means 22 outputs the received ultrasonic signal to the amplitude determination means 23, and when detecting the ultrasonic signal having a predetermined amplitude or more, the propagation time measurement means 24 determines that the propagation time measurement is completed. Then, it is also output to the flow rate calculation means 25.

  As the gas replacement proceeds, the supply gas gradually enters the gas shut-off device, and the air and the supply gas flow while being mixed. When an ultrasonic signal is transmitted in such a state, the ultrasonic wave reaches the receiving-side transceiver while passing through the supply gas or air, or the air and the supply gas alternately appearing during propagation. At this time, if the medium suddenly passes through the supply gas having a different density from a medium having a low propagation speed such as air, the propagation time is short and the propagation time is shortened.

  Here, since the signal detection control means 22 is controlled by the time obtained from the long propagation time measured in the previous air state, the signal detection control means 22 still receives and receives an ultrasonic signal having a predetermined amplitude level or more in the signal detection stopped state. Thereafter, the signal detection control means 22 starts detection, but the ultrasonic signal has already attenuated, and if it happens that noise or the like having a predetermined amplitude or more occurs, the propagation time is erroneously measured to obtain the instantaneous flow rate. Since the propagation time is measured in such a state, the flow rate obtained by the flow rate calculation means 25 is not stable and varies not only on the plus side but also on the minus side.

  When such a flow rate fluctuation signal is input to the flow rate change determination unit 26, the mixed gas state is determined and a flow rate change detection signal is output to the signal detection calculation unit 27. The signal detection calculation means 27 obtains a signal detection control time from the propagation time obtained in the previous measurement and the second signal detection correction value. As a result, since the second signal detection correction value including the supply gas is a value capable of detecting a short propagation time, the signal detection control means 22 starts signal detection at an early stage. An ultrasonic signal can always be detected even if the propagation time measured by the mixed gas state changes. When the apparatus is used to sufficiently replace the supply pipe with the supply gas and the state of switching to the supply gas is detected by the flow rate change determination means 26, the correction value in the signal detection calculation means 27 returns to the normal correction value and is calculated. To do. Once the flow rate fluctuation is detected, the flow is stabilized.

  On the other hand, the average flow rate calculation means 29 calculates the instantaneous flow rate obtained by the flow rate calculation means 25 as an average flow rate value for each predetermined number. At the same time, the use amount is integrated by the integration means 32 for the instantaneous flow rate. As for the obtained average flow rate, the abnormality determining means 30 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 the hose that supplies gas to the stove or the like is disconnected for some reason, an abnormally large flow rate occurs. To monitor such a situation, the total flow cutoff value or the normal use of the instrument is used as an initial setting value. A time limit for shutting down the use time that defines a time limit for use time corresponding to a case where the use time is much longer than the maximum use time is stored. When the average flow rate is monitored and determined to be abnormal, the shut-off means 31 is driven to stop the supply gas.

  As described above, the piping state and piping conditions differ depending on each gas customer, and if the supply gas having different density and the other gas (for example, air and city gas 13A) are once mixed and continued, an abnormal flow rate change occurs. In order to change the signal cutoff time of the signal detection control means 22 by detecting the change in flow rate and changing the correction value, it is ensured even if the propagation state suddenly becomes faster or shorter depending on the medium type due to the mixed state. An ultrasonic signal can be captured, and an abnormal flow rate is prevented, so that it is not accidentally interrupted or integrated with an abnormal flow rate. Since the gas shut-off device operates normally, safety and reliability are extremely high, and there is an effect that the gas business operator is not required to be activated due to erroneous shut-off and is highly usable.

  Note that the configuration used in the present embodiment is an example, and the usage pattern is not limited to the present embodiment.

(Embodiment 2)
FIG. 2 is a control block diagram of the gas cutoff device according to Embodiment 2 of the present invention. The same components as those in FIG. 1 are denoted by the same reference numerals.

  FIG. 2 is a control block diagram of the shut-off device. Reference numeral 34 denotes a signal detection initial correction means, which is usually a first signal detection correction value (a correction value for starting control of the signal detection control means 22 before the amplitude determination means 23 detects a signal so as not to erroneously detect noise). The initial set value is set as the signal detection correction time.

  Next, the operation of the gas shut-off device configured as described above will be described. The gas shut-off device is installed in a newly built house, or a new large-sized device is installed or replaced. Replace the air in the piping with the supply gas. At this time, a small flow rate instrument such as a gas table may be used. When the pipe length from the gas shut-off device to the gas instrument is long like a detached house, it takes a long time to replace the gas.

  When flow measurement is performed under such conditions in the pipe, the following phenomenon may occur. Over time, in the flow path, different gases such as supply gas and air are mixed due to convection and the like, and the vicinity of the upstream transmitter / receiver 16 and the downstream transmitter / receiver 17 in the gas shutoff device also takes longer time. It becomes a mixed state. The ultrasonic wave transmitted by the upstream side transceiver 16 or the downstream side transceiver 17 propagates in the mixed gas, and propagates in the gas having a fast propagation time every time measured by the intermittent control means 14. If so, the case of propagating in the air with a slow propagation time occurs discontinuously.

  When the inside of the gas pipe is only air, the propagation time is slower and the propagation time is measured by the propagation time measuring means 24 as compared with the original supply gas (for example, city gas such as 13A). The flow rate detecting means 15 is periodically driven by the intermittent control means 14. First, the upstream transceiver 16 is driven by the transmission means 19 and is received by the downstream transceiver. The receiving means 20 amplifies the received signal and outputs it to the signal detection control means 22. The signal detection control unit 22 stops signal detection until the time obtained by the signal detection initial correction unit 34 elapses. Since the initial time is set until the first upstream / downstream propagation time is obtained, the signal detection stop is released early. When the next measurement time elapses, the signal detection stop time is shorter than the propagation time. When the time measuring unit 28 counts up, the signal detection control unit 22 starts detection, and outputs an ultrasonic signal received thereafter to the amplitude determination unit 23. The amplitude determination means 23 determines whether the ultrasonic signal has an amplitude grown above a predetermined level. When an ultrasonic signal having an amplitude of a predetermined level or more is detected, it is determined that reception is completed, and a completion notification is sent to the propagation time measuring means 24. For the obtained propagation time, the flow rate calculation means 25 determines the instantaneous flow rate.

  Even if the replacement is started, if the gas shut-off device is only air, the instantaneous flow rate obtained by the flow rate computing means 25 is monitored by the flow rate change judging means 26, and a stable flow rate state is obtained. The signal detection initial correction means 34 obtains the signal detection start time from the propagation time in the air medium and the first signal detection correction value. The obtained time is counted by the time measuring means 28, and when it has elapsed, a detection start signal is output to the signal detection control means 22. When the signal detection control means 22 receives the signal detection start, the signal detection control means 22 outputs the received ultrasonic signal to the amplitude determination means 23, and when detecting the ultrasonic signal having a predetermined amplitude or more, the propagation time measurement means 24 determines that the propagation time measurement is completed. Then, it is also output to the flow rate calculation means 25.

  As the gas replacement proceeds, the supply gas gradually enters the gas shut-off device, and the air and the supply gas flow while being mixed. When an ultrasonic signal is transmitted in such a state, the ultrasonic wave reaches the receiving-side transceiver while passing through the supply gas or air, or the air and the supply gas alternately appearing during propagation. At this time, if the medium suddenly passes through the supply gas having a different density from a medium having a low propagation speed such as air, the propagation time is short and the propagation time is shortened. Since the signal detection control means 22 is controlled by the time obtained from the long propagation time measured in the previous air state, the signal detection control means 22 still reaches and receives the ultrasonic signal having a predetermined amplitude level or more in the signal detection stopped state. After that, the signal detection control means 22 starts detection, but if the ultrasonic signal has already attenuated and it happens that noise or the like exceeds a predetermined amplitude, the propagation time is erroneously measured and the instantaneous flow rate is obtained. Since the propagation time is measured in such a state, the flow rate obtained by the flow rate calculation means 25 is not stable and varies not only on the plus side but also on the minus side.

  Such a flow rate fluctuation signal is inputted to the flow rate change judging means 26, but it is judged as a mixed gas state, and a flow rate fluctuation detection signal is outputted to the signal detection initial correcting means 34. In this case, the signal detection initial correction means 34 outputs the initial set value to the time measurement means 28 as the signal detection control time. As a result, since the initial correction value including the supply gas is a value capable of detecting a short propagation time, the signal detection control means 22 starts signal detection early. An ultrasonic signal can always be detected even if the propagation time measured by the mixed gas state changes. When the apparatus is used to sufficiently replace the supply pipe with the supply gas and the state of switching to the supply gas is detected by the flow rate change determination means 26, the correction value in the signal detection initial correction means 34 is the normal first signal. Return to the detection correction value. Once the flow rate fluctuation is detected, it is performed until it stabilizes.

  On the other hand, the average flow rate calculation means 29 calculates the instantaneous flow rate obtained by the flow rate calculation means 25 as an average flow rate value for each predetermined number. At the same time, the use amount is integrated by the integration means 32 for the instantaneous flow rate. As for the obtained average flow rate, the abnormality determining means 30 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 the hose that supplies gas to the stove or the like is disconnected for some reason, an abnormally large flow rate occurs. To monitor such a situation, the total flow cutoff value or the normal use of the instrument is used as an initial setting value. A time limit for shutting down the use time that defines a time limit for use time corresponding to a case where the use time is much longer than the maximum use time is stored. When the average flow rate is monitored and determined to be abnormal, the shut-off means 31 is driven to stop the supply gas.

  In this way, the piping state and piping conditions differ depending on each gas customer, and once the supply gas having a different density and other gas (for example, air and city gas 13A) are mixed, the flow rate is detected and an initial correction value is obtained. Since the signal cut-off time of the signal detection control means 22 is varied by switching to the above, even if the mixed state occurs and the propagation time suddenly increases or decreases depending on the medium type, the ultrasonic signal can be reliably captured, Therefore, there is no possibility of accidental shut-off or erroneous accumulation with an abnormal flow rate. Since the gas shut-off device operates normally, safety and reliability are extremely high, and there is an effect that the gas business operator is not required to be activated due to erroneous shut-off and is highly usable.

(Embodiment 3)
FIG. 3 is a control block diagram of the gas cutoff device according to Embodiment 3 of the present invention. The same number is attached | subjected to the equivalent to FIG.1, FIG.2 and FIG.5.

  FIG. 3 is a control block diagram of the shut-off device. Reference numeral 35 denotes a flow rate determining means. If any minute flow rate flows due to the instantaneous flow rate obtained by the flow rate calculating means 25, it is determined that the flow rate is present, and a flow rate display signal is output to the display unit of the notification communication means 33. When the display is turned off, output is performed. Also, when the ultrasonic measuring unit is in a mixed state with a different gas, the flow rate change determining means 26 can detect only a flow rate fluctuation less than a predetermined flow rate depending on the piping state of the gas consumer, and there is a display output depending on the mixed gas state. When the flow amount of the level flows, a correction value output signal capable of further early control of the signal detection start is output to the signal detection calculation means 27.

  Next, the operation of the gas shut-off device configured as described above will be described. The gas shut-off device is installed in a newly built house, or a new large-sized device is installed or replaced. Replace the air in the piping with the supply gas. In some cases, a small flow rate device such as a gas table is used, and when the pipe length from the gas shut-off device to the gas device is long like a detached house, it takes a long time to replace the gas.

  When flow measurement is performed under such conditions in the pipe, the following phenomenon may occur. Over time, in the flow path, different gases such as supply gas and air are mixed due to convection and the like, and the vicinity of the upstream transmitter / receiver 16 and the downstream transmitter / receiver 17 in the gas shutoff device also takes longer time. It becomes a mixed state. The ultrasonic wave transmitted by the upstream side transceiver 16 or the downstream side transceiver 17 propagates in the mixed gas, and propagates in the gas having a fast propagation time every time measured by the intermittent control means 14. If so, the case of propagating in the air with a slow propagation time occurs discontinuously.

  When the inside of the gas pipe is only air, the propagation time is slower and the propagation time is measured by the propagation time measuring means 24 as compared with the original supply gas (for example, city gas such as 13A). The flow rate detecting means 15 is periodically driven by the intermittent control means 14. First, the upstream transceiver 16 is driven by the transmission means 19 and is received by the downstream transceiver. The receiving means 20 amplifies the received signal and outputs it to the signal detection control means 22. The signal detection control unit 22 stops signal detection until the time obtained by the signal detection calculation unit 27 elapses. Since the initial time is set until the first upstream / downstream propagation time is obtained, the signal detection stop is released early. When the next measurement time elapses, the signal detection stop time is shorter than the propagation time. When the time measuring unit 28 counts up, the signal detection control unit 22 starts detection, and outputs an ultrasonic signal received thereafter to the amplitude determination unit 23. The amplitude determination means 23 determines whether the ultrasonic signal has an amplitude grown above a predetermined level. When an ultrasonic signal having an amplitude of a predetermined level or more is detected, it is determined that reception is completed, and a completion notification is sent to the propagation time measuring means 24. For the obtained propagation time, the flow rate calculation means 25 determines the instantaneous flow rate.

  Even if the replacement is started, if the gas shut-off device is only air, the instantaneous flow rate obtained by the flow rate calculation unit 25 is monitored by the flow rate change determination unit 26, and a stable flow rate state is obtained. The signal detection calculation means 27 obtains the signal detection start time from the propagation time in the air medium and the first signal detection correction value. The obtained time is counted by the time measuring means 28, and when it has elapsed, a detection start signal is output to the signal detection control means 22. When the signal detection control means 22 receives the signal detection start, the signal detection control means 22 outputs the received ultrasonic signal to the amplitude determination means 23, and when detecting the ultrasonic signal having a predetermined amplitude or more, the propagation time measurement means 24 determines that the propagation time measurement is completed. Then, it is also output to the flow rate calculation means 25.

  As the gas replacement progresses, the supply gas (for example, city gas 13A) gradually enters the gas shut-off device and flows while the air and the supply gas are mixed. When an ultrasonic signal is transmitted in such a state, the ultrasonic wave reaches the receiving-side transceiver while passing through the supply gas or air, or the air and the supply gas alternately appearing during propagation. At this time, if the medium suddenly passes through the supply gas having a different density from a medium having a low propagation speed such as air, the propagation time is short and the propagation time is shortened. Since the signal detection control means 22 is controlled by the time obtained from the long propagation time measured in the previous air state, the signal detection control means 22 still reaches and receives the ultrasonic signal having a predetermined amplitude level or more in the signal detection stopped state. After that, the signal detection control means 22 starts detection, but if the ultrasonic signal has already attenuated and it happens that noise or the like exceeds a predetermined amplitude, the propagation time is erroneously measured and the instantaneous flow rate is obtained. Since the propagation time is measured in such a state, the flow rate obtained by the flow rate calculation means 25 is not stable and varies not only on the plus side but also on the minus side.

  The flow rate fluctuation state at this time varies depending on the installation state and piping state of each gas consumer. The flow rate change determining means 26 may not reach the predetermined flow rate for determining the abnormal mixing state even if the flow rate fluctuation is detected, but if the flow rate is less than the predetermined flow rate, the flow rate determining means 35 may determine that the flow rate is present. . If the flow rate determining means 35 determines that there is a flow rate, the display unit of the notification communication means 33 displays the flow rate present, and if the flow rate is detected, it is determined that there is a possibility of a mixed gas state and the flow rate fluctuation detection signal is signal-detected and calculated. It outputs to the means 27. The signal detection calculation means 27 obtains a signal detection control time from the propagation time obtained in the previous measurement and the second signal detection correction value. As a result, since the second signal detection correction value including the supply gas is a value capable of detecting a short propagation time, the signal detection control means 22 starts signal detection at an early stage. An ultrasonic signal can always be detected even if the propagation time measured by the mixed gas state changes. When the apparatus is used to sufficiently replace the supply pipe with the supply gas and the state of switching to the supply gas is detected by the flow rate change determination means 26, the correction value in the signal detection calculation means 27 returns to the normal correction value and is calculated. To do. Once the flow rate fluctuation is detected, it is performed until it stabilizes.

  On the other hand, the average flow rate calculation means 29 calculates the instantaneous flow rate obtained by the flow rate calculation means 25 as an average flow rate value for each predetermined number. At the same time, the use amount is integrated by the integration means 32 for the instantaneous flow rate. As for the obtained average flow rate, the abnormality determining means 30 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 the hose that supplies gas to the stove or the like is disconnected for some reason, an abnormally large flow rate occurs. To monitor such a situation, the total flow cutoff value or the normal use of the instrument is used as an initial setting value. A time limit for shutting down the use time that defines a time limit for use time corresponding to a case where the use time is much longer than the maximum use time is stored. When the average flow rate is monitored and determined to be abnormal, the shut-off means 31 is driven to stop the supply gas.

  In this way, the piping state and piping conditions differ depending on each gas consumer, and the flow rate changes once the supply gas having a different density and the other gas (for example, 13A of air and city gas) are mixed. Even if the presence / absence determination means 35 determines that there is a possibility of a mixed gas state even in the case of a minute flow rate with a flow rate level, the signal detection start correction value is switched and the signal cutoff time of the signal detection control means 22 is varied. Even if the propagation time suddenly becomes faster or shorter depending on the type of medium, it is possible to reliably capture an ultrasonic signal and prevent an abnormal flow rate. It is not integrated with the flow rate. Since the gas shut-off device operates normally, safety and reliability are extremely high, and there is an effect that the gas business operator is not required to be activated due to erroneous shut-off and is highly usable.

(Embodiment 4)
FIG. 4 is a diagram showing a control block diagram of the gas cutoff device according to Embodiment 4 of the present invention. 1, 2, 3, and 5 are denoted by the same reference numerals.

  FIG. 4 is a control block diagram of the shut-off device. Reference numeral 34 denotes a signal detection initial correction means. The initial detection value of the signal detection control means 22 and the first signal detection correction value (the signal detection control means 22 before the signal is detected by the amplitude determination means 23 so as to prevent erroneous detection of noise). Correction value for starting control) is stored. Reference numeral 35 denotes a flow rate determining means. If any minute flow rate flows due to the instantaneous flow rate obtained by the flow rate calculating means 25, it is determined that the flow rate is present, and a flow rate display signal is output to the display unit of the notification communication means 33. When the display is turned off, output is performed. Also, when the ultrasonic measuring unit is in a mixed state with a different gas, the flow change determination means 26 can detect only a flow rate fluctuation less than a predetermined flow rate according to the piping state of the gas customer. When a flow of a certain level flows, signal detection correction output is performed to the signal detection initial correction means 34.

  Next, the operation of the gas shut-off device configured as described above will be described. The gas shut-off device is installed in a newly built house, or a new large-sized device is installed or replaced. Replace the air in the piping with the supply gas. In some cases, a small flow rate appliance such as a gas table is used, and the length of the pipe from the gas shut-off device to the gas appliance varies depending on the detached house or apartment house, and it takes a long time to replace the gas.

  When flow measurement is performed under such conditions in the pipe, the following phenomenon may occur. Over time, in the flow path, different gases such as supply gas and air are mixed due to convection and the like, and the vicinity of the upstream transmitter / receiver 16 and the downstream transmitter / receiver 17 in the gas shutoff device also takes longer time. It becomes a mixed state. The ultrasonic wave transmitted by the upstream side transceiver 16 or the downstream side transceiver 17 propagates in the mixed gas, and propagates in the gas having a fast propagation time every time measured by the intermittent control means 14. If so, the case of propagating in the air with a slow propagation time occurs discontinuously.

  When the inside of the gas pipe is only air, the propagation time is slower and the propagation time is measured by the propagation time measuring means 24 as compared with the original supply gas (for example, city gas such as 13A). The flow rate detecting means 15 is periodically driven by the intermittent control means 14. First, the upstream transceiver 16 is driven by the transmission means 19 and is received by the downstream transceiver. The receiving means 20 amplifies the received signal and outputs it to the signal detection control means 22. The signal detection control unit 22 stops signal detection until the time set by the signal detection initial correction unit 34 elapses. Until the very first upstream / downstream propagation time is measured, the signal detection start setting time is the initial value, so that the signal detection stop is released early. When the next measurement time elapses, the signal detection stop time (propagation time-first signal detection correction time) obtained based on the propagation time is obtained. When the time measuring unit 28 counts up, the signal detection control unit 22 starts detection, and outputs an ultrasonic signal received thereafter to the amplitude determination unit 23. The amplitude determination means 23 determines whether the ultrasonic signal has an amplitude grown above a predetermined level. When an ultrasonic signal having an amplitude of a predetermined level or more is detected, it is determined that reception is completed, and a completion notification is sent to the propagation time measuring means 24. For the obtained propagation time, the flow rate calculation means 25 determines the instantaneous flow rate.

  Even if the replacement is started, if the gas shut-off device is only air, the instantaneous flow rate obtained by the flow rate computing means 25 is monitored by the flow rate change judging means 26, and a stable flow rate state is obtained. The signal detection initial correction means 34 obtains the signal detection start time from the propagation time in the air medium and the first signal detection correction value. The obtained time is counted by the time measuring means 28, and when it has elapsed, a detection start signal is output to the signal detection control means 22. When the signal detection control means 22 receives the signal detection start, the signal detection control means 22 outputs the received ultrasonic signal to the amplitude determination means 23, and when detecting the ultrasonic signal having a predetermined amplitude or more, the propagation time measurement means 24 determines that the propagation time measurement is completed. Then, it is also output to the flow rate calculation means 25.

  As the gas replacement progresses, the supply gas (for example, city gas 13A) gradually enters the gas shut-off device and flows while the air and the supply gas are mixed. When an ultrasonic signal is transmitted in such a state, the ultrasonic wave reaches the receiving-side transceiver while passing through the supply gas or air, or the air and the supply gas alternately appearing during propagation. At this time, if the medium suddenly passes through the supply gas having a different density from a medium having a low propagation speed such as air, the propagation time is short and the propagation time is shortened. Since the signal detection control means 22 is controlled by the time obtained from the long propagation time measured in the previous air state, the signal detection control means 22 still reaches and receives the ultrasonic signal having a predetermined amplitude level or more in the signal detection stopped state. After that, the signal detection control means 22 starts detection, but if the ultrasonic signal has already attenuated and it happens that noise or the like exceeds a predetermined amplitude, the propagation time is erroneously measured and the instantaneous flow rate is obtained. Since the propagation time is measured in such a state, the flow rate obtained by the flow rate calculation means 25 is not stable and varies not only on the plus side but also on the minus side.

  The flow rate fluctuation state at this time varies depending on the installation state and piping state of each gas consumer. The flow rate fluctuation level of the flow rate change determining means 26 may not reach a predetermined flow rate that is determined to be the most abnormal mixed state. However, even when the flow rate is lower than the predetermined flow rate, a mixed gas state may occur. That is, the flow rate value obtained in the mixed gas state may be the displayed flow rate level. Accordingly, in such a case, a display with a flow rate is displayed, and when the flow rate is detected, it is determined that there is a possibility of a mixed gas state, and a flow rate fluctuation detection signal is output to the signal detection initial correction means 34. The signal detection initial correction means 34 switches to the initial signal detection start time. As a result, the signal detection time of the initial value including the supply gas is a value that can be detected even with a short propagation time of most gas types, so the signal detection control means 22 starts signal detection early. An ultrasonic signal can always be detected even if the propagation time measured by the mixed gas state changes. When the apparatus is used to sufficiently replace the inside of the supply pipe with the supply gas and the state of switching to the supply gas is detected by the flow rate change determination means 26, the correction value in the signal detection initial correction means 34 returns to the normal correction value. Calculate. Once the flow rate fluctuation is detected, it is performed until it stabilizes.

  On the other hand, the average flow rate calculation means 29 calculates the instantaneous flow rate obtained by the flow rate calculation means 25 as an average flow rate value for each predetermined number. At the same time, the use amount is integrated by the integration means 32 for the instantaneous flow rate. As for the obtained average flow rate, the abnormality determining means 30 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 the hose that supplies gas to the stove or the like is disconnected for some reason, an abnormally large flow rate occurs. To monitor such a situation, the total flow cutoff value or the normal use of the instrument is used as an initial setting value. A time limit for shutting down the use time that defines a time limit for use time corresponding to a case where the use time is much longer than the maximum use time is stored. When the average flow rate is monitored and determined to be abnormal, the shut-off means 31 is driven to stop the supply gas.

  In this way, the piping state and piping conditions differ depending on each gas consumer, and the flow rate changes once the supply gas having a different density and the other gas (for example, 13A of air and city gas) are mixed. Even if the presence / absence determination unit 35 determines that there is a possibility of a mixed gas state even in the case of a minute flow rate with a flow rate level, the signal detection time is switched to the initial value and the signal cutoff time of the signal detection control unit 22 is made variable. Even if the propagation time suddenly becomes faster or shorter depending on the medium type, it is possible to reliably capture the ultrasonic signal and prevent abnormal flow rates. Therefore, it is not accumulated at abnormal flow rate. Since the gas shut-off device operates normally, safety and reliability are extremely high, and there is an effect that the gas business operator is not required to be activated due to erroneous shut-off and is highly usable.

  As described above, the gas shut-off device according to the present invention is intended to prevent measurement abnormality due to different media in the supply pipe at the time of installation, and similarly measures the flow rate of a water meter or the like that is a mixture of liquid and gas. It can be applied to all devices.

16 Upstream transmitter / receiver (transmitter / receiver)
17 Downstream transmitter / receiver (transmitter / receiver)
DESCRIPTION OF SYMBOLS 18 Switching means 19 Transmission means 20 Reception means 22 Signal detection control means 23 Amplitude determination means 24 Propagation time measurement means 25 Flow rate calculation means 26 Flow rate change determination means 27 Signal detection calculation means 28 Time measurement means 29 Average flow rate calculation means 30 Abnormality determination means 31 Blocking means 34 Signal detection initial correction means 35 Flow rate existence judging means

Claims (2)

A pair of transceivers arranged along the flow path and transmitting and receiving ultrasonic signals;
Switching means for switching transmission / reception of the pair of transceivers;
Transmission means for driving the transceiver set on the transmission side by the switching means;
Receiving means for receiving an ultrasonic signal from the transceiver set on the receiving side by the switching means;
Signal detection control means for controlling the detection start time of the received signal from the receiving means;
Amplitude determining means for determining whether or not a received signal from the receiving means has a predetermined ultrasonic signal level;
Propagation time measuring means for measuring the time from the start of driving by the transmitting means until signal detection by the amplitude determining means;
A flow rate calculating means for calculating an instantaneous flow rate from a measurement value of the propagation time measuring means;
A flow rate determining means for performing a flow rate output when detecting a flow rate of a predetermined value or more from the flow rate calculation means;
Signal detection calculation means for obtaining a correction time for advancing the signal detection start time of the signal detection control means when detecting the flow existence state by the flow existence judgment means,
Time measuring means for counting time based on the calculation result of the signal detection calculating means and outputting a signal detection start signal to the signal detection control means;
Average flow rate calculating means for obtaining an average flow rate from the instantaneous flow rate obtained by the flow rate calculating means;
An abnormality determining means for determining the presence or absence of an abnormality from the average flow rate obtained by the average flow rate calculating means;
A gas shut-off device comprising: a shut-off means for shutting off the gas supply when the abnormality judgment is established by the abnormality judgment means. A pair of transceivers arranged along the flow in the flow path for transmitting and receiving ultrasonic signals;
Switching means for switching transmission / reception of the pair of transceivers;
Transmission means for driving the transceiver set on the transmission side by the switching means;
Receiving means for receiving an ultrasonic signal from the transceiver set on the receiving side by the switching means;
Signal detection control means for controlling the time for starting detection of the received signal from the receiving means;
Amplitude determining means for determining whether or not a received signal from the receiving means has a predetermined ultrasonic signal level;
Propagation time measuring means for measuring the time from the start of driving by the transmitting means until signal detection by the amplitude determining means;
A flow rate calculating means for calculating an instantaneous flow rate from a measurement value of the propagation time measuring means;
A flow rate determining means for performing a flow rate output when detecting a flow rate of a predetermined value or more from the flow rate calculation means;
Signal detection initial correction means for returning the signal detection time of the signal detection control means to an initial set value when the flow existence determination means detects the flow existence state,
Time measuring means for counting time from the output of the signal detection initial correcting means and outputting a signal detection start signal to the signal detection control means;
Average flow rate calculating means for obtaining an average flow rate from the instantaneous flow rate obtained by the flow rate calculating means;
An abnormality determining means for determining the presence or absence of an abnormality from the average flow rate obtained by the average flow rate calculating means;
A gas shut-off device comprising: a shut-off means for shutting off the gas supply when the abnormality judgment is established by the abnormality judgment means.

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