JP2012103060A - Ultrasonic gas meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic gas meter capable of preventing wasted man hours and transportation cost from being caused by reducing erroneous shutoff while protecting safety and measurement performance, and to provide a control method for the ultrasonic gas meter.SOLUTION: A μCOM 14 includes: an ultrasonic wave receiving error determination function which determines whether or not an ultrasonic signal is in a normal state where it is normally transmitted and received; a gain error determination function which determines whether or not the amplification degree for modifying the received ultrasonic signal is the normal state within a predetermined range; and a propagation time error determination function which determines whether or not the propagation time from transmission of the ultrasonic signal up to reception thereof is within a predetermined time range, and performs the closing operation of a gas shut-off valve 10 when the normal state is not determined.

Description

  The present invention relates to an ultrasonic gas meter.

  Currently, an ultrasonic gas meter using an ultrasonic flow velocity sensor has been proposed (for example, Patent Document 1). In the ultrasonic gas meter described above, an ultrasonic flow sensor is constituted by two acoustic transducers composed of, for example, piezoelectric transducers that operate at an ultrasonic frequency that are arranged at a predetermined distance in the gas flow path.

  Then, the ultrasonic signal generated by one transducer is received by the other transducer to measure the propagation time during which the ultrasonic signal propagates between the transducers, and the gas flow rate is intermittent based on the measured propagation time. The passage flow rate is obtained by multiplying the flow rate by the sectional area of the gas flow path and the intermittent time. Furthermore, an ultrasonic gas meter can be configured by displaying the integrated flow rate obtained by integrating the passing flow rate.

JP 2006-242658 A

  However, in ultrasonic gas meters, electronic circuits related to ultrasonic flow rate sensors and flow measurement functions are broken, negative pressure conditions in which the pressure in the meter flow path is negative, and mixing in which air enters the meter flow path. A gas state and a different gas state in which a different gas such as a helium gas different from the detection target enters the meter flow path are generated. In such a case, the safety of the ultrasonic gas meter cannot be maintained and accurate measurement cannot be performed, and the quality cannot be guaranteed.

  The present invention has been made to solve such conventional problems, and an object of the present invention is to provide an ultrasonic gas meter capable of protecting safety and measurement performance. .

  The ultrasonic gas meter according to the present invention includes a transmission unit that intermittently transmits an ultrasonic signal in a gas flow path, a reception unit that receives an ultrasonic signal, and a reception unit that receives the ultrasonic signal after the transmission unit transmits the ultrasonic signal. A first function for monitoring a propagation time until the ultrasonic signal is received by the means and determining whether the signal reaches a normal state within a predetermined time; and an amplification factor for amplifying the ultrasonic signal received by the receiving means A second function for determining whether the normal state is within a predetermined range, and the propagation time from when the ultrasonic signal is transmitted by the transmitting unit to when the ultrasonic signal is received by the receiving unit is within the predetermined time range A determination means having at least one of a third function for determining whether the state is normal, and a cutoff that shuts off the gas flow in the gas flow path by closing the shut-off valve when the determination means determines that the state is not normal Means and Characterized in that it comprises a.

  According to the ultrasonic gas meter of the present invention, the first function of monitoring the propagation time from when an ultrasonic signal is transmitted until it is received and determining whether the signal reaches a normal state within a predetermined time, and the reception A second function for determining whether the amplification level for amplifying the ultrasonic signal is within a predetermined range and a normal state in which the propagation time from when the ultrasonic signal is transmitted to when it is received is within the predetermined time range If it is determined that the state is not normal, the shut-off valve is closed to stop the flow of gas in the gas flow path. Here, failure of an electronic circuit related to the ultrasonic flow rate sensor and the flow measurement function, a negative pressure state in which the pressure in the meter flow path is negative, a mixed gas state in which air is mixed in the meter flow path, and If a different gas state such as helium gas that is different from the detection target enters the meter flow path, the ultrasonic signal may not reach within the predetermined time, or the amplification level may be outside the predetermined range. . Also, the propagation time may be out of the predetermined time range. Therefore, it is possible to protect safety and measurement performance by having at least one of the above three functions and closing the shut-off valve when an error occurs.

  In the ultrasonic gas meter according to the present invention, when the determining means determines that the shut-off means is not in a normal state, the shut-off valve is not closed when the measured pressure value after the determination is less than the threshold value. It is preferable to close the shut-off valve when the pressure measurement value is equal to or greater than the threshold value.

  According to the ultrasonic gas meter of the present invention, when it is determined that the state is not normal, the shutoff valve is not closed when the pressure measurement value after the determination is less than the threshold value. Here, in a situation where a negative pressure state or when the ultrasonic gas meter itself is removed from the pipe and becomes a mixed gas state, it is misidentified as an error although it is not an essential error. In many cases, the measured pressure value is less than a threshold value. For this reason, it is possible to reduce the frequency of erroneously shutting off the shut-off valve in an unrecoverable manner due to an error that is not an error, thereby avoiding inspection at a factory or the like. On the other hand, since the shutoff valve is closed when the measured pressure value after determination is equal to or greater than a predetermined value, the gas shutoff valve is shut off in an unrecoverable manner when quality cannot be guaranteed. Therefore, while protecting safety and measurement performance, it is possible to reduce false interruptions and prevent wasteful man-hours and transportation costs caused by inspection in a factory or the like.

  In addition, the ultrasonic gas meter of the present invention learns at least one of a gas consumption pattern indicating a tendency of gas consumption after a predetermined time has elapsed after first detecting a flow rate of a predetermined value or more, and a usage time for each flow rate category. Learning means for starting the operation, and the determination means does not perform a determination as to whether or not it is in a normal state before learning by the learning means is started and a flow rate equal to or higher than a specified value is first detected. It is preferable to perform a determination as to whether or not the flow rate is normal after learning is started and a flow rate equal to or greater than the specified value is first detected.

  Further, according to the ultrasonic gas meter of the present invention, before learning is started and before a flow rate equal to or higher than a specified value is detected for the first time, it is not determined whether or not it is in a normal state. After the flow rate exceeding the specified value is detected, a determination is made as to whether or not the flow rate is normal. For this reason, the determination as to whether or not it is in a normal state is started at an early stage. For example, a gas meter whose quality cannot be guaranteed can be determined at an early stage, for example, when water enters the flow path.

  In addition, the ultrasonic gas meter of the present invention learns at least one of a gas consumption pattern indicating a tendency of gas consumption after a predetermined time has elapsed after first detecting a flow rate of a predetermined value or more, and a usage time for each flow rate category. Learning means for starting the learning and ending the learning after the elapse of a specific time, and the determination means does not perform the determination as to whether or not the learning means is normal before the learning by the learning means is completed. After the completion, it is preferable to execute a determination as to whether or not the state is normal.

  In addition, according to the ultrasonic gas meter of the present invention, the determination as to whether or not the normal state is performed is not performed before the learning is completed, and the determination as to whether or not the normal state is performed after the learning is completed. Here, a mixed gas state or a different gas state occurs immediately after the installation of the gas meter. Further, since normal gas is used during the learning period, the mixed gas state and the different gas state are eliminated by learning. Therefore, before the learning is completed, the mixed gas state or the different gas state is resolved by performing the determination as to whether or not the normal state is performed after the learning is completed without performing the determination as to whether or not the normal state is reached. In this state, it can be determined whether or not it is in a normal state, and a situation in which the shut-off valve is closed due to an erroneous determination can be prevented.

  Further, in the ultrasonic gas meter according to the present invention, when the determination unit can acquire the adjustment pressure during learning by the learning unit, the determination unit determines whether or not the learning unit is in a normal state even before the learning by the learning unit is completed. It is preferable.

  Further, according to the ultrasonic gas meter of the present invention, when the adjustment pressure can be acquired during learning, it is determined whether or not it is in a normal state even before learning ends. Here, the adjustment pressure is acquired only after the gas flows to some extent. For this reason, it can be said that the mixed gas state and the different gas state are eliminated by the use of the gas. Therefore, when the adjustment pressure can be acquired, it is possible to determine a gas meter whose quality cannot be guaranteed earlier by determining whether or not it is in a normal state even before learning ends.

  In the ultrasonic gas meter of the present invention, it is preferable that the determination unit determines whether or not the initial state is normal.

  Further, according to the ultrasonic gas meter of the present invention, since it is determined whether or not it is normal from the initial state, it is determined whether or not it is normal from the time of shipment from the factory, for example, shipped from the factory. When an ultrasonic sensor or its internal circuit breaks down during transportation of the ultrasonic gas meter, the shut-off valve can be shut off to notify the failure when the gas meter is installed.

  According to the ultrasonic gas meter of the present invention, safety and measurement performance can be protected.

It is a lineblock diagram showing the ultrasonic gas meter concerning the embodiment of the present invention. FIG. 2 is a configuration diagram showing the inside of μCOM shown in FIG. 1. It is a flowchart which shows the control method of the ultrasonic gas meter which concerns on this embodiment. It is a flowchart which shows the control method of the ultrasonic gas meter when it is judged that it is effective in the process shown in FIG.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings. FIG. 1 is a configuration diagram illustrating an ultrasonic gas meter according to an embodiment of the present invention. The ultrasonic gas meter 1 shown in FIG. 1 includes two acoustic transducers (disposed by a distance L in the gas flow path and opposed to each other so as to form an angle θ with respect to the gas flow direction Y). (Transmission means, reception means) TD1, TD2.

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

  Each transducer TD1, TD2 is connected to a transmitter circuit 12 and a receiver circuit 13 via transducer interface (I / F) circuits 11a, 11b, respectively. The transmission circuit 12 transmits, in the form of a pulse burst, a signal for driving one of the transducers TD1 and TD2 to generate an ultrasonic signal under the control of the microcomputer (μCOM) 14.

  The receiving circuit 13 includes an amplifier 13a that receives signals from the other transducers TD1 and TD2 that have received the ultrasonic signal that has passed through the gas flow path and amplifies the ultrasonic signal to a predetermined intensity. The amplification degree of the amplifier 13a can be adjusted by the μCOM 14. Further, a display 15 and a return button 16 are connected to the μCOM 14.

  FIG. 2 is a block diagram showing the inside of the μCOM 14 shown in FIG. As shown in FIG. 2, the μCOM 14 includes a central processing unit (CPU) 14a that performs various processes according to a program, a ROM 14b that is a read-only memory that stores a program for processing performed by the CPU 14a, and various types of CPU 14a. A RAM 14c, which is a readable / writable memory having a work area used in the processing process, a data storage area for storing various data, and the like are incorporated. These are connected to each other by a bus line 14d.

  Further, the CPU 14a has a determination function (determination unit), an error blocking function (blocking unit), and a learning function (learning unit).

  The determination function includes three functions: an ultrasonic reception error determination function (first function), a gain error determination function (second function), and a propagation time error determination function (third function). These errors include transducers TD1 and TD2, I / F circuits 11a and 11b, transmitter circuit 12 and receiver circuit 13, etc., a negative pressure state in which the pressure in the meter flow path becomes negative, and air in the meter flow path. This occurs in a mixed gas state in which gas is mixed and in a different gas state in which a different gas such as helium gas different from the detection target enters the meter flow path.

  The ultrasonic wave reception error determination function monitors the propagation time from when an ultrasonic signal is transmitted by one transducer TD1, TD2 until the ultrasonic signal is received by the other transducer TD1, TD2, and within a predetermined time. This is a function for determining whether the signal reaches a normal state. The ultrasonic wave reception error determination function determines that the state is abnormal when the arrival time is not within the predetermined time, and determines that the state is normal when the arrival time is within the predetermined time. Here, the predetermined time is an initial value of 400 ms in the present embodiment.

  The gain error determination function is a function for determining whether or not the amplification degree (gain value) for amplifying the ultrasonic signals received by the other transducers TD1 and TD2 is within a predetermined range. The gain error determination function determines that it is in an abnormal state when the gain value is not within the predetermined range, and determines that it is in a normal state when the gain value is within the predetermined range. Here, the predetermined range is an initial value of 20 or more and 77 or less in the present embodiment.

  The propagation time error judgment function determines whether or not the propagation time from when an ultrasonic signal is transmitted by one transducer TD1 and TD2 to when the ultrasonic signal is received by the other transducer TD1 and TD2 is within a predetermined time range. It is a function to judge whether. The propagation time error determination function determines that the state is abnormal when the propagation time is not within the predetermined time range, and determines that the state is normal when the propagation time is within the predetermined time range. Here, the predetermined time range is 135 μs or more and 330 μs or less in the present embodiment.

  The error cutoff function is a function for closing the gas cutoff valve 10 to stop the gas flow in the gas flow path. This error shut-off function shuts off the gas shut-off valve 10 to an unrecoverable state for the reason that the quality of the ultrasonic gas meter 1 cannot be guaranteed when it is judged that the judgment function is not in a normal state. Thereby, the ultrasonic gas meter 1 which concerns on this embodiment can aim at protection about safety | security and measurement performance.

  However, the error cutoff function may cause the gas cutoff valve 10 to be erroneously shut off. In the ultrasonic gas meter 1 according to the present embodiment, the frequency of such erroneous interruption is also reduced. Details will be described below. For example, when a rubber hose is used for piping or depending on the temperature difference between day and night, a negative pressure state occurs in the ultrasonic gas meter 1. Specifically, if a rubber hose is used in a part of the gas pipe of a newly built house, the main plug is closed after the gas is supplied once, and if the gas is not supplied for a while, the gas remaining in the pipe It may be absorbed by the rubber hose and become a negative pressure state. Moreover, since the gas pressure changes by about 0.4 kPa due to a temperature change of 1 ° C., a negative pressure state occurs due to a temperature change from daytime to nighttime. More specifically, when the gas is used in a pipe using a rubber hose during the summer day and the valve is closed for several days after being used for a few days, when the temperature falls at night, the pressure drops below the atmospheric pressure and becomes -40 to 40 It may be about -60 kPa.

  In such a case, although there is no problem in the ultrasonic gas meter itself, the gas shutoff valve is erroneously shut off in a non-recoverable state due to the influence of the negative pressure state. In that case, the gas company will send a gas meter to the factory and carry out re-inspection, resulting in unnecessary man-hours and transportation costs.

  Similarly, in a state where the ultrasonic gas meter 1 is removed, a mixed gas state of the gas to be measured and air occurs. In these cases, the above error occurs, and the ultrasonic gas meter 1 is sent to the factory and reinspected.

  Therefore, in order to prevent erroneous interruption, the error interruption function reads a pressure measurement value from a pressure sensor (not shown) when the determination function determines that the state is not normal. When the measured pressure value is less than the threshold value, the error cutoff function determines that the negative pressure state or the ultrasonic gas meter 1 has been removed and is in a mixed gas state, and the gas cutoff valve 10 is closed. I won't let you. On the other hand, when the measured pressure value is not less than the threshold value, the error cutoff function does not determine the negative pressure state or the mixed gas state, but determines that it is an essential error and closes the gas cutoff valve 10.

  The learning function is a function for learning the usage state of the gas. This learning function is executed after a predetermined time (for example, 1 hour) has elapsed since the ultrasonic gas meter 1 is installed and a flow rate of a predetermined value (for example, 21 L / h) or more is detected for the first time. The contents learned here are a gas consumption pattern indicating a tendency of gas consumption and a gas usage time for each flow rate category.

  This learning function monitors the gas flow rate for 14 days (specific time) during learning, divides the 14 days into the first 3 days and the last 11 days, and sets the flow cutoff value for closing the gas cutoff valve 10. Set according to gas consumption pattern. The flow rate cutoff value includes a total flow rate cutoff value and an increased flow rate cutoff value. In addition, the learning function monitors the gas use time for each flow rate section, and sets the continuous use shut-off time for causing the gas shut-off valve 10 to be closed for each flow rate section. The learning function ends learning after 14 days.

  Further, in this embodiment, the propagation time error determination function determines whether or not the normal state is reached before learning by the learning function is started and a flow rate of a specified value (for example, 21 L / h) or more is first detected. After the learning by the learning function is started and a flow rate equal to or higher than a specified value (for example, 21 L / h) is first detected, it is determined whether or not it is in a normal state. For this reason, the determination as to whether or not the propagation time is in a normal state is started at an early stage. For example, a gas meter whose quality cannot be guaranteed can be determined at an early stage, for example, when water enters the flow path.

  In the present embodiment, only the propagation time error determination function is as described above. However, the present invention is not limited to this, and the same may be applied to the ultrasonic wave reception error determination function and the gain error determination function.

  Furthermore, in this embodiment, the gain error determination function does not execute the determination as to whether or not the learning function is in a normal state before learning by the learning function is finished, and is the normal state after the learning by the learning function is completed. Make a decision of no. Here, after the ultrasonic gas meter 1 is installed, a mixed gas state or a different gas state may be generated. However, the gas or the like in the ultrasonic gas meter 1 escapes through the gas appliance due to subsequent use of the gas. That is, the mixed gas state and the different gas state are eliminated by using the gas. Accordingly, the gain error determination function does not execute the determination as to whether or not the normal state is reached until the 14-day learning is completed, and the determination as to whether or not the gain error determination function is in the normal state is performed after the learning ends. In addition, it is possible to make an error determination at the stage where the different gas state is eliminated, and it is possible to prevent a situation where the shutoff valve is closed due to an erroneous determination.

  In addition, in the present embodiment, the gain error determination function executes a determination as to whether or not it is in a normal state even during learning when an adjustment pressure (for example, about 3 kPa) can be acquired from a signal from a pressure sensor during learning. To do. Here, the adjustment pressure is acquired only after the gas flows to some extent. For this reason, it can be said that the mixed gas state and the different gas state are eliminated by the use of the gas. Therefore, in the above case, it is possible to determine a gas meter whose quality cannot be guaranteed earlier by determining whether or not it is in a normal state.

  In the present embodiment, only the gain error determination function is as described above. However, the present invention is not limited to this, and the same may be applied to the ultrasonic wave reception error determination function and the propagation time error determination function.

  Further, in the present embodiment, the ultrasonic wave reception error determination function determines whether or not the normal state from the initial state. For this reason, it is determined whether or not it is in a normal state from the time of factory shipment. For example, during the transportation of the ultrasonic gas meter 1 shipped from the factory, the transducers TD1, TD2, I / F circuits 11a, 11b. When the transmission circuit 12, the reception circuit 13, etc. fail and an ultrasonic reception error occurs, the gas cutoff valve 10 is shut off. Thereby, the gas company can notify that the gas meter 1 is out of order when the gas meter is installed.

  In the present embodiment, only the ultrasonic wave reception error determination function is as described above. However, the present invention is not limited to this, and the same may be applied to the gain error determination function and the propagation time error determination function.

  Next, a detailed operation of the ultrasonic gas meter 1 according to the present embodiment will be described with reference to a flowchart. FIG. 3 is a flowchart showing the operation of the ultrasonic gas meter 1 according to this embodiment.

  As shown in FIG. 3, first, the CPU 14a enables the ultrasonic wave reception error determination function (S1). Thereby, the ultrasonic wave reception error determination function is effective from the initial state, and it is determined whether or not the ultrasonic wave reception error is in a normal state at the time of factory shipment and during the transportation of the ultrasonic gas meter 1. Therefore, when the transducers TD1 and TD2, I / F circuits 11a and 11b, the transmission circuit 12 and the reception circuit 13 and the like break down during transportation and an ultrasonic reception error occurs, the gas cutoff valve 10 is shut off. . Thereby, the gas company can know that the gas meter is out of order when the gas meter is installed.

  Next, the CPU 14a determines whether learning has started (S2). If it is determined that learning has not started (S2: NO), this process is repeated until it is determined that learning has started. On the other hand, when it is determined that learning has started (S2: YES), the CPU 14a determines whether or not a flow rate equal to or greater than a specified value has been generated after learning has started (S3).

  If it is determined that a flow rate greater than the specified value has not been generated after the start of learning (S3: NO), this process is repeated until it is determined that a flow rate greater than the specified value has been generated. When it is determined that a flow rate equal to or greater than the specified value has been generated after the start of learning (S3: YES), the CPU 14a validates the propagation time error determination function (S4). As a result, the determination as to whether or not the propagation time is in a normal state is started at an early stage. For example, a gas meter whose quality cannot be guaranteed can be determined at an early stage, for example, when water enters the flow path.

  Next, the CPU 14a determines whether or not the adjustment pressure has been acquired (S5). If it is determined that the adjusted pressure has been acquired (S5: YES), it can be said that the gas has flowed to some extent, and it can be said that the mixed gas state or the different gas state has been eliminated by the use of the gas. For this reason, the CPU 14a validates the gain error determination function (S7). Then, the process shown in FIG. 3 ends.

  When it is determined that the adjustment pressure has not been acquired (S5: NO), the CPU 14a determines whether the learning has been completed (S6). If it is determined that learning has not ended (S6: NO), the process proceeds to step S5. On the other hand, if it is determined that the learning has been completed (S6: YES), it is assumed that the mixed gas state or the different gas state has been eliminated, so the CPU 14a validates the gain error determination function (S7). Then, the process shown in FIG. 3 ends.

  FIG. 4 is a flowchart showing a control method of the ultrasonic gas meter 1 when it is determined to be effective in the processing shown in FIG. As shown in FIG. 4, first, the error determination function determines whether or not it is in a normal state (S11). In this processing, the effective one of the ultrasonic wave reception error determination function, gain error determination function, and propagation time error determination function executes error determination.

  That is, the ultrasonic reception error determination function determines whether or not the ultrasonic signal can be normally transmitted and received to determine whether or not it is in a normal state, and the gain error determination function determines that the gain value of the ultrasonic signal is within a predetermined range. It is determined whether or not it is normal. Further, the propagation time error determination function determines whether or not the propagation time of the ultrasonic signal is within a predetermined time range to determine whether or not it is in a normal state.

  When it is determined that the state is not normal (S11: NO), the CPU 14a increments the counter value (S12), and determines whether the counter value is equal to or greater than the error determination value (S13). Here, the error determination value is “100” in the case of an ultrasonic reception error, and “1800” in the case of a gain error and a propagation time error. These values are preferably variable.

  If it is determined that the counter value is not greater than or equal to the error determination value (S13: NO), the process proceeds to step S11. On the other hand, when it is determined that the counter value is equal to or greater than the error determination value (S13: YES), the error cutoff function determines whether or not the pressure measurement value is less than the threshold value (S14).

  When it is determined that the pressure measurement value is not less than the threshold value (S14: NO), the error cutoff function shuts off the gas cutoff valve 10 so that it cannot be restored (S15). Then, the process shown in FIG. 4 ends.

  Further, when it is determined that the pressure measurement value is less than the threshold (S14: YES) and when it is determined that the pressure is normal (S11: YES), the CPU 14a resets the counter value (S16). Thereafter, the process shown in FIG. 4 ends.

  In this way, according to the ultrasonic gas meter 1 according to the present embodiment, the propagation time from when an ultrasonic signal is transmitted to when it is received is monitored, and whether or not the signal reaches a normal state within a predetermined time. An ultrasonic reception error determination function for determining, a gain error determination function for determining whether the amplification level for amplifying the received ultrasonic signal is within a predetermined range, and a reception state after the ultrasonic signal is transmitted And at least one of a propagation time error determination function for determining whether the normal propagation state is within a predetermined time range, and when it is determined that the normal state is not normal, the shut-off valve is closed to operate the gas flow path. Stop the gas flow at. Here, transducers TD1 and TD2, I / F circuits 11a and 11b, transmitter circuit 12 and receiver circuit 13, etc., a negative pressure state in which the pressure in the meter flow path becomes negative, air is mixed in the meter flow path When a mixed gas state occurs and a different gas state such as helium gas different from the detection target enters the meter flow path, the ultrasonic signal does not reach within a predetermined time or the amplification degree is predetermined. Or out of range. Also, the propagation time may be out of the predetermined time range. Therefore, it is possible to protect safety and measurement performance by having at least one of the above three functions and closing the gas cutoff valve 10 when an error occurs.

  Further, when it is determined that the state is not normal, the gas cutoff valve 10 is not closed when the measured pressure value after the determination is less than the threshold value. Here, when it is in a negative pressure state or when the ultrasonic gas meter 1 itself is removed from the pipe and becomes a mixed gas state, a situation in which it is mistaken as an error although it is not an essential error In many cases, the measured pressure value is less than a threshold value. For this reason, although it is not an error, the frequency which misidentifies it as an error and erroneously shuts off the gas shut-off valve 10 so that it cannot be restored can be reduced, and inspection at a factory or the like can be avoided. On the other hand, when the measured pressure value after the determination is equal to or greater than the predetermined value, the gas shut-off valve 10 is closed. Therefore, if the quality cannot be guaranteed, the gas shut-off valve 10 is shut off in an unrecoverable manner. Therefore, while protecting safety and measurement performance, it is possible to reduce false interruptions and prevent wasteful man-hours and transportation costs caused by inspection in a factory or the like.

  In addition, before learning is started and the flow rate exceeding the specified value is detected for the first time, it is not determined whether the state is normal, and after learning is started and the flow rate exceeding the specified value is detected for the first time. Then, it is determined whether or not it is in a normal state. For this reason, the determination as to whether or not it is in a normal state is started at an early stage. For example, a gas meter whose quality cannot be guaranteed can be determined at an early stage, for example, when water enters the flow path.

  Further, before learning is completed, the determination as to whether or not it is in a normal state is not performed, and after learning is completed, the determination as to whether or not it is in a normal state is performed. Here, a mixed gas state or a different gas state occurs immediately after the installation of the gas meter 1 or the like. Further, since normal gas is used during the learning period, the mixed gas state and the different gas state are eliminated by learning. Therefore, before the learning is completed, the mixed gas state or the different gas state is resolved by performing the determination as to whether or not the normal state is performed after the learning is completed without performing the determination as to whether or not the normal state is reached. In this state, it can be determined whether or not it is in a normal state, and a situation in which the gas cutoff valve 10 is closed due to an erroneous determination can be prevented.

  Further, when the adjustment pressure can be acquired during learning, it is determined whether or not it is in a normal state even before learning ends. Here, the adjustment pressure is acquired only after the gas flows to some extent. For this reason, it can be said that the mixed gas state and the different gas state are eliminated by the use of the gas. Therefore, when the adjustment pressure can be acquired, it is possible to determine a gas meter whose quality cannot be guaranteed earlier by determining whether or not it is in a normal state even before learning ends.

  In addition, since it is determined whether or not it is normal from the initial state, it is determined whether or not it is normal from the time of shipment from the factory. For example, during the transportation of the ultrasonic gas meter 1 shipped from the factory, ultrasonic waves are transmitted. When the sensor or its internal circuit breaks down, the gas shut-off valve 10 can be shut off to notify the trouble when the gas meter is installed.

  As described above, the present invention has been described based on the embodiment, but the present invention is not limited to the above embodiment, and may be modified without departing from the gist of the present invention. For example, in the above embodiment, each value is not limited to the above value, and can be changed as appropriate.

  Furthermore, in the present embodiment, the determination function is composed of three functions of an ultrasonic wave reception error determination function, a gain error determination function, and a propagation time error determination function. Also good. That is, it is only necessary to execute at least one of the three functions.

  In addition, in this embodiment, the propagation time error determination function does not perform the determination as to whether or not the normal state before the learning by the learning function is started and the flow rate exceeding the specified value is first detected. After learning by function is started and a flow rate equal to or higher than a specified value is detected for the first time, a determination is made as to whether or not it is in a normal state. However, the present invention is not limited to the propagation time error determination function, and may be applied to an ultrasonic wave reception error determination function and a gain error determination function.

  Similarly, the gain error determination function does not execute the determination as to whether or not the normal state is obtained before the learning by the learning function is finished, and determines whether or not the normal state is obtained after the learning by the learning function is finished. Make a decision. However, the present invention is not limited to the gain error determination function, and may be applied to an ultrasonic wave reception error determination function and a propagation time error determination function.

  In addition, the ultrasonic wave reception error determination function determines whether or not the normal state from the initial state. However, the present invention is not limited to the ultrasonic wave reception error determination function, and may be applied to a gain error determination function and a propagation time error determination function.

DESCRIPTION OF SYMBOLS 1 ... Ultrasonic gas meter 10 ... Gas cutoff valve 11a, 11b ... Transducer I / F circuit 12 ... Transmission circuit 13 ... Reception circuit 13a ... Amplifier 14 ... μCOM
14a ... CPU (determination means, blocking means, learning means)
14b ... ROM
14c ... RAM
14d ... Bus line 15 ... Display 16 ... Return button TD1, TD2 ... Acoustic transducer (transmitting means, receiving means)

Claims (6)

Transmission means for intermittently transmitting ultrasonic signals in the gas flow path;
Receiving means for receiving the ultrasonic signal;
A first function for monitoring a propagation time from when the ultrasonic signal is transmitted by the transmitting unit to when the ultrasonic signal is received by the receiving unit, and determining whether the signal reaches a normal state within a predetermined time; A second function for determining whether the amplification level of the ultrasonic signal received by the receiving means is within a predetermined range and a normal state; and after the ultrasonic signal is transmitted by the transmitting means, the receiving means A determination unit having at least one of a third function for determining whether the propagation time until the ultrasonic signal is received is in a normal state within a predetermined time range;
A shut-off means for closing the shut-off valve to stop the gas flow in the gas flow path when the judgment means determines that the state is not normal;
An ultrasonic gas meter comprising: The shut-off means does not close the shut-off valve when the pressure measurement value after the judgment is less than the threshold when the judgment means determines that the normal state is not normal, and when the pressure measurement value after the judgment is greater than or equal to the threshold The ultrasonic gas meter according to claim 1, wherein the shut-off valve is closed. A gas consumption pattern indicating a tendency of gas consumption after elapse of a specified time after first detecting a flow rate equal to or greater than a predetermined value, and learning means for starting learning about at least one of the usage times for each flow rate category
The determination means does not perform a determination as to whether or not a normal state is detected before the learning by the learning means is started and a flow rate equal to or higher than a predetermined value is detected for the first time. 2. The ultrasonic gas meter according to claim 1, wherein a determination is made as to whether or not a normal state is detected after a flow rate greater than a specified value is detected. Start learning for at least one of the gas consumption pattern that shows the tendency of gas consumption after the elapse of a specified time after the first detection of a flow rate that is equal to or greater than a predetermined value, and the usage time for each flow rate category. Further comprising learning means for ending,
The determination means does not execute the determination as to whether or not it is in a normal state before the learning by the learning means ends, and executes the determination as to whether or not it is in a normal state after the learning by the learning means ends. The ultrasonic gas meter according to claim 1, wherein 5. The determination unit, when the adjustment pressure can be acquired during learning by the learning unit, executes a determination as to whether or not the learning unit is in a normal state even before the learning by the learning unit is completed. The ultrasonic gas meter according to 1. The ultrasonic gas meter according to claim 1, wherein the determination unit determines whether or not the initial state is a normal state.

Images