JP6087695B2 - Ultrasonic gas meter - Google Patents

Description

  The present invention provides a pair of ultrasonic waves that are arranged at predetermined intervals between an internal flow path through which a gas to be flow-measured flows and an upstream side and a downstream side of the internal flow path and alternately transmit ultrasonic waves. An ultrasonic flow rate measurement unit that includes a sound wave transmission / reception unit, amplifies a reception signal of each of the pair of ultrasonic transmission / reception units, and calculates a gas flow rate based on the amplified reception signal; A shut-off valve provided in the internal flow path and electrically switchable from a valve-opened state to a valve-closed state, and a shut-off valve for detecting the valve-opening return from the valve-closed state to the valve-opened state of the shut-off valve An abnormality is detected on the basis of the measurement information of the return detection means and the flow rate measurement means, and when the abnormality is detected, a shut-off process at the time of switching the shut-off valve to the closed state is executed, and the shut-off The shut-off valve is opened by valve return detection means. An ultrasonic type comprising control means configured to execute a return-time leakage determination process for determining whether or not gas leakage has occurred downstream from the shut-off valve when a return is detected; It relates to a gas meter.

Such an ultrasonic gas meter measures the flow rate of gas supplied to a gas demand destination such as a house, and measures the gas consumption at the gas demand destination. For example, when an abnormality in gas consumption at a gas demand destination is detected and the abnormality is detected, a shut-off process at the time of switching the shut-off valve to a closed state is executed to automatically supply the gas to the gas demand destination. It has a security function that blocks it automatically.
Then, when the abnormal shut-off process is performed and the gas supply is shut off, after the abnormality is resolved, an operation for returning the shut-off valve to the open state is performed artificially. Will be returned to the open state, but as the return of the shut-off valve is detected by the shut-off valve return detecting means, the presence or absence of gas leakage downstream from the shut-off valve is determined. It also has a security function that executes leak detection processing at return.

  By the way, as a flow rate measuring means for measuring a gas flow rate, there are a membrane type and an ultrasonic type. The membrane-type flow rate measuring means alternately feeds and discharges gas to and from a pair of measuring chambers partitioned by a diaphragm, converts the reciprocating motion associated therewith to rotate the rotating body, and rotates the rotating body. The gas flow rate is measured based on the detection of. On the other hand, the ultrasonic flow rate measurement means alternately transmits ultrasonic waves through a pair of ultrasonic transmission / reception means arranged at predetermined intervals on the upstream side and the downstream side of the internal flow path, The ultrasonic wave transmitted from the ultrasonic transmission / reception unit is driven so as to be received by the other ultrasonic transmission / reception unit, the propagation time of the ultrasonic wave from the upstream side to the downstream side and the ultrasonic wave from the downstream side to the upstream side. The propagation time is measured, and the gas flow rate is measured based on the measurement information.

As a conventional technique for the leakage determination process at the time of return, the following technique is disclosed in a film type gas meter provided with a film type flow rate measuring means.
That is, if the gas flow rate measured by the flow rate measuring unit exceeds the predetermined set flow rate for a predetermined set time after the shut-off valve return detection unit detects the open valve return, the gas leakage occurs. A leakage judgment process at the time of return for determining that occurrence has occurred is disclosed (see, for example, Patent Document 1).

JP 59-122819 A

By the way, in recent years, in order to reduce the size, weight, and accuracy of gas meters, ultrasonic gas meters equipped with ultrasonic flow rate measuring means have become widespread.
However, in such an ultrasonic gas meter, even if the return leakage determination process disclosed in Patent Document 1 described above is adopted as the return leakage determination process, gas leakage is appropriately prevented as described below. There is a possibility that a case where the determination cannot be made may occur, and the return leakage determination process disclosed in Patent Document 1 cannot be applied to the ultrasonic gas meter.

  That is, the leakage judgment process at the time of return is executed when an abnormality occurs at a gas customer where an ultrasonic gas meter is already installed and gas is consumed. It is also executed when an ultrasonic gas meter is installed in a gas supply pipe that supplies gas to a gas demanding party, such as at the time of installation or new installation. That is, since the installation of the ultrasonic gas meter is performed with the shut-off valve closed, the return leakage determination process is executed when the shut-off valve is opened and returned after the installation. When the ultrasonic gas meter is installed, the internal flow path of the ultrasonic gas meter is filled with air. When the shut-off valve is opened in such a state, the internal flow path is upstream. Since the gas flows from the air and the air in the internal flow channel is pushed downstream, the gas region and the air region coexist in the internal flow channel without sufficiently mixing the gas and air. (Hereinafter sometimes referred to as a gas / air phase coexistence state) can appear.

Since the acoustic impedance is different between the gas region and the air region, when a gas / air phase coexistence state appears in the internal flow path, a fault having different acoustic impedance appears in the internal flow path. And since the ultrasonic wave transmitted from each ultrasonic transmission / reception means is easily reflected by a tomography having different acoustic impedance, when a gas-air phase coexistence state appears in the internal flow path, the reception signal of each ultrasonic transmission / reception means is Compared to the case where gas alone, air alone, or a fluid in which they are sufficiently mixed (hereinafter, may be collectively referred to as “homogeneous fluid”) exist in the internal flow path. The amplification degree when the received signal of the ultrasonic transmission / reception means is amplified to a predetermined range is increased.
Accordingly, even if the received signal of each ultrasonic transmission / reception means is amplified to calculate the fluid flow rate, if the received signal is too small, the calculation error of the fluid flow rate increases, so the flow rate of the fluid flowing through the internal flow path Cannot be properly measured, and in such a return leakage determination process based on the fluid flow rate measurement information, it may not be possible to appropriately determine whether or not gas leakage has occurred.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an ultrasonic gas meter that can appropriately determine the presence or absence of gas leakage when the shut-off valve is opened again.

The characteristic configuration of the ultrasonic gas meter according to the present invention includes an internal flow path through which a gas to be flow-measured flows,
Provided with a pair of ultrasonic transmission / reception means that are arranged at predetermined intervals on the upstream side and the downstream side of the internal flow path and alternately transmit ultrasonic waves, and receive signals of the pair of ultrasonic transmission / reception means respectively An ultrasonic flow rate measuring means for measuring the gas flow rate by amplifying and calculating the gas flow rate based on the amplified received signal;
A shut-off valve provided in the internal flow path and electrically switchable from a valve-open state to a valve-closed state;
A shut-off valve return detecting means for detecting a return of the shut-off valve from the closed state to the open state;
An abnormality is detected based on the measurement information of the flow rate measuring means, and when the abnormality is detected, a shut-off process at the time of switching the shut-off valve to the closed state is executed, and the shut-off valve return detecting means A control means configured to execute a return-time leakage determination process for determining whether or not a gas leak has occurred downstream of the cutoff valve when a valve opening return of the cutoff valve is detected; With
The characteristic configuration is that a part of the internal flow path is configured by a plurality of parallel measurement flow paths,
Corresponding to each of the plurality of measurement flow paths, the flow rate measuring means is provided, and the control means is measured by a plurality of flow rate measurement means respectively provided in the plurality of measurement flow paths. Based on the fluid flow rate, the fluid flow rate is configured to detect the abnormality, and in the return leakage determination process, the fluid flow rate measured by the flow rate measurement unit whose amplification level of the received signal is equal to or less than a set amplification level. On the basis of the fluid flow rate of the internal flow path, to determine whether the gas leakage has occurred based on the determined fluid flow rate of the internal flow path ,
In the leakage judgment process at the time of return, when the amplification degree of the reception signals of all the plurality of flow rate measurement means is larger than the set amplification degree, the fluid flow rate of the internal flow path is zero. In view of this, it is determined whether or not the gas leakage has occurred .

According to the above characteristic configuration, the gas for flow rate measurement flows through a plurality of parallel measurement channels, and a plurality of measurement flows are provided by a plurality of flow rate measuring means provided in each of the plurality of measurement channels. The fluid flow rate of each flow path is measured, and an abnormality is detected by the control means based on the fluid flow rate measurement information of the plurality of flow rate measurement means. For example, the sum of the fluid flow rates measured by each of the plurality of flow rate measurement means is used as the gas flow rate of the internal flow path, and the presence / absence of an abnormality is determined based on the gas flow rate of the internal flow path.
Further, in the return leakage determination process, the control means obtains the fluid flow rate of the internal flow path based on the fluid flow rate measured by the flow rate measurement means whose received signal amplification is equal to or less than the set amplification degree, Based on the fluid flow rate of the internal flow path thus determined, it is determined whether or not gas leakage has occurred. For example, if a plurality of measurement channels are designed to have the same fluid flow rate, and the fluid flow rates of the measurement channels are the same, the flow rate of the received signal is equal to or less than the set amplification rate By correcting the sum of the fluid flow rates measured by the measuring means by the ratio of the number of flow rate measuring means whose received signal amplification is less than or equal to the set amplification level and the total number of flow rate measuring means, the fluid in the internal flow path A flow rate is required. Incidentally, the set amplification degree is a condition that is larger than the amplification degree at which the reception signal of the ultrasonic transmission / reception means is amplified by the flow rate measurement means when, for example, a homogeneous fluid exists between the pair of ultrasonic transmission / reception means. Thus, the value is appropriately set to a predetermined value.

In other words, by configuring a part of the internal flow path with a plurality of parallel measurement flow paths, the shut-off valve can be used when the internal flow path is filled with air, such as when an ultrasonic gas meter is installed. Even when gas flows from the upstream side into the internal flow path when opened, the gas / air phase coexistence between the pair of ultrasonic transmission / reception means is not established for all measurement flow paths. It is possible to have a measurement flow path in which a homogeneous fluid exists without the presence of an air phase between the ultrasonic transmission / reception means.
In this situation, for the measurement flow channel where the gas / air phase is not coexisting between the pair of ultrasonic transmission / reception means, the reception signal of each ultrasonic transmission / reception means has a normal size, and amplification for amplifying the reception signal The degree is equal to or less than the set amplification degree, and the fluid flow rate in the measurement channel is accurately calculated based on the reception signal thus amplified.
Then, based on the fluid flow rate of the measurement flow path that is accurately measured by the flow rate measuring means whose received signal amplification level is equal to or less than the set amplification level, the fluid flow rate of the internal flow path is obtained with high accuracy. Since it is determined whether or not gas leakage has occurred based on the fluid flow rate of the internal flow path determined with high accuracy, this determination can be made appropriately.
Further, in the leakage judgment process at the time of return, when the amplification level of the reception signals of all the plurality of flow rate measuring means is larger than the set amplification level, it is considered that the fluid flow rate of the internal flow path is zero, and the It is determined whether or not gas leakage has occurred on the downstream side.
In other words, if no gas leakage occurs downstream from the shutoff valve, the shutoff valve is opened and gas flows into the internal flow path from the upstream side, and fluid such as gas or air enters the internal flow path. After filling, the gas and air inside the plurality of measurement flow paths do not flow at all or almost downstream. Therefore, when the amplification level of the reception signals of all the plurality of flow rate measurement means is larger than the set amplification level, the gas and air inside the plurality of measurement flow paths are not flowing at all or almost downstream, Since it can be considered that all of the plurality of measurement flow paths are in the gas / air phase coexistence state, the fluid flow rate of the internal flow path can be regarded as zero.
Therefore, some of the measurement flow paths are in a gas / air phase coexistence state, all are in a gas / air phase coexistence state, or all are not in a gas / air phase coexistence state. Regardless of the state of being present, it is possible to appropriately determine the presence or absence of gas leakage when the shut-off valve is opened again.
Therefore, it is possible to provide an ultrasonic gas meter that can appropriately determine the presence or absence of gas leakage when the shut-off valve is opened again.

Further features of the ultrasonic gas meter according to the present invention are as follows:
In the leakage judgment process at the time of return, when the amplification degree of the reception signal of a part of the plurality of flow measurement means is equal to or less than the set amplification degree, the amplification degree of the reception signal Is a flow rate of fluid measured by the flow rate measuring means below the set amplification level, and each of the plurality of flow rate measurement means when the amplification levels of the received signals of all the plurality of flow rate measurement means are below the set amplification level. The correction is based on the ratio of the measured fluid flow rate, so that the fluid flow rate of the internal flow path is obtained.

According to the above characteristic configuration, when the amplification degree of the reception signal of a part of the plurality of flow rate measurement means is equal to or less than the set amplification level, the flow rate measurement means whose amplification level of the reception signal is equal to or less than the set amplification level To correct the fluid flow rate measured by the ratio of the fluid flow rate measured by each of the plurality of flow rate measurement means when the amplification of the received signals of all of the plurality of flow rate measurement means is less than or equal to the set amplification degree Thus, since the fluid flow rate of the internal flow path is obtained, the fluid flow rate of the internal flow path can be obtained accurately even if the ratio of the fluid flow rates in the plurality of measurement flow paths varies.
By the way, when the amplification degree of the reception signal of a part of the plurality of flow measurement means is equal to or less than the set amplification degree, the amplification degree of the reception signal is set to the set amplification degree when the fluid flow rate in the internal flow path is obtained. It is assumed that the fluid flow rate measured by the following flow rate measuring means is obtained by correcting the fluid flow rate in a plurality of predetermined measurement flow paths.
However, in this case, if the ratio of the fluid flow rates in the plurality of measurement channels varies with time, the accuracy of the obtained fluid flow rate in the internal channels may be reduced.
In short, according to this characteristic configuration, when the fluid flow rate measured by the flow rate measurement unit whose received signal amplification is equal to or less than the set amplification rate is corrected to obtain the fluid flow rate of the internal flow path, a plurality of flow rate measurement units are used. Since the correction is made based on the ratio of the fluid flow rates in the plurality of measurement channels actually measured, even if the ratio of the fluid flow rates in the plurality of measurement channels fluctuates over time, the fluid in the internal channel The flow rate can be obtained with high accuracy, and the presence or absence of gas leakage can be appropriately determined when the shut-off valve is opened again.

The characteristic configuration of the ultrasonic gas meter according to the present invention includes an internal flow path through which a gas to be flow-measured flows,
Provided with a pair of ultrasonic transmission / reception means that are arranged at predetermined intervals on the upstream side and the downstream side of the internal flow path and alternately transmit ultrasonic waves, and receive signals of the pair of ultrasonic transmission / reception means respectively An ultrasonic flow rate measuring means for measuring the gas flow rate by amplifying and calculating the gas flow rate based on the amplified received signal;
A shut-off valve provided in the internal flow path and electrically switchable from a valve-open state to a valve-closed state;
A shut-off valve return detecting means for detecting a return of the shut-off valve from the closed state to the open state;
An abnormality is detected based on the measurement information of the flow rate measuring means, and when the abnormality is detected, a shut-off process at the time of switching the shut-off valve to the closed state is executed, and the shut-off valve return detecting means A control means configured to execute a return-time leakage determination process for determining whether or not a gas leak has occurred downstream of the cutoff valve when a valve opening return of the cutoff valve is detected; With
The characteristic configuration is that a part of the internal flow path is configured by a plurality of parallel measurement flow paths,
Corresponding to each of the plurality of measurement channels, the flow rate measuring means is provided,
The control means is configured to detect the abnormality based on a fluid flow rate measured by a plurality of flow rate measurement means provided in each of the plurality of measurement flow paths, and the return leakage In the determination process, the fluid flow rate of the internal flow path is obtained based on the fluid flow rate measured by the flow rate measuring means whose amplification level of the received signal is equal to or less than the set amplification level, and the fluid flow rate of the internal flow path thus obtained is determined. To determine whether or not the gas leakage has occurred,
In the leakage judgment process at the time of return, when the amplification degree of the reception signal of a part of the plurality of flow measurement means is equal to or less than the set amplification degree, the amplification degree of the reception signal Is a flow rate of fluid measured by the flow rate measuring means below the set amplification level, and each of the plurality of flow rate measurement means when the amplification levels of the received signals of all the plurality of flow rate measurement means are below the set amplification level. The correction is based on the ratio of the measured fluid flow rate, so that the fluid flow rate of the internal flow path is obtained.

According to the above characteristic configuration, the gas for flow rate measurement flows through a plurality of parallel measurement channels, and a plurality of measurement flows are provided by a plurality of flow rate measuring means provided in each of the plurality of measurement channels. The fluid flow rate of each flow path is measured, and an abnormality is detected by the control means based on the fluid flow rate measurement information of the plurality of flow rate measurement means. For example, the sum of the fluid flow rates measured by each of the plurality of flow rate measurement means is used as the gas flow rate of the internal flow path, and the presence / absence of an abnormality is determined based on the gas flow rate of the internal flow path.
Further, in the return leakage determination process, the control means obtains the fluid flow rate of the internal flow path based on the fluid flow rate measured by the flow rate measurement means whose received signal amplification is equal to or less than the set amplification degree, Based on the fluid flow rate of the internal flow path thus determined, it is determined whether or not gas leakage has occurred. For example, if a plurality of measurement channels are designed to have the same fluid flow rate, and the fluid flow rates of the measurement channels are the same, the flow rate of the received signal is equal to or less than the set amplification rate By correcting the sum of the fluid flow rates measured by the measuring means by the ratio of the number of flow rate measuring means whose received signal amplification is less than or equal to the set amplification level and the total number of flow rate measuring means, the fluid in the internal flow path A flow rate is required. Incidentally, the set amplification degree is a condition that is larger than the amplification degree at which the reception signal of the ultrasonic transmission / reception means is amplified by the flow rate measurement means when, for example, a homogeneous fluid exists between the pair of ultrasonic transmission / reception means. Thus, the value is appropriately set to a predetermined value.
In other words, by configuring a part of the internal flow path with a plurality of parallel measurement flow paths, the shut-off valve can be used when the internal flow path is filled with air, such as when an ultrasonic gas meter is installed. Even when gas flows from the upstream side into the internal flow path when opened, the gas / air phase coexistence between the pair of ultrasonic transmission / reception means is not established for all measurement flow paths. It is possible to have a measurement flow path in which a homogeneous fluid exists without the presence of an air phase between the ultrasonic transmission / reception means.
In this situation, for the measurement flow channel where the gas / air phase is not coexisting between the pair of ultrasonic transmission / reception means, the reception signal of each ultrasonic transmission / reception means has a normal size, and amplification for amplifying the reception signal The degree is equal to or less than the set amplification degree, and the fluid flow rate in the measurement channel is accurately calculated based on the reception signal thus amplified.
Then, based on the fluid flow rate of the measurement flow path that is accurately measured by the flow rate measuring means whose received signal amplification level is equal to or less than the set amplification level, the fluid flow rate of the internal flow path is obtained with high accuracy. Since it is determined whether or not gas leakage has occurred based on the fluid flow rate of the internal flow path determined with high accuracy, this determination can be made appropriately.
Further, when the amplification degree of the reception signal of a part of the plurality of flow rate measurement means is equal to or less than the set amplification degree, the amplification factor of the reception signal is measured by the flow rate measurement means that is equal to or less than the set amplification degree. By correcting the fluid flow rate based on the ratio of the fluid flow rate measured by each of the plurality of flow rate measurement units when the amplification level of the reception signals of all the multiple flow rate measurement units is equal to or less than the set amplification level, Therefore, even if the ratio of the fluid flow rates in the plurality of measurement flow paths fluctuates, the fluid flow rate in the internal flow path can be obtained with high accuracy.
Therefore, it is possible to provide an ultrasonic gas meter that can appropriately determine the presence or absence of gas leakage when the shut-off valve is opened again.

By the way, when the amplification degree of the reception signal of a part of the plurality of flow measurement means is equal to or less than the set amplification degree, the amplification degree of the reception signal is set to the set amplification degree when the fluid flow rate in the internal flow path is obtained. It is assumed that the fluid flow rate measured by the following flow rate measuring means is obtained by correcting the fluid flow rate in a plurality of predetermined measurement flow paths.
However, in this case, if the ratio of the fluid flow rates in the plurality of measurement channels varies with time, the accuracy of the obtained fluid flow rate in the internal channels may be reduced.
In short, according to this characteristic configuration, when the fluid flow rate measured by the flow rate measurement unit whose received signal amplification is equal to or less than the set amplification rate is corrected to obtain the fluid flow rate of the internal flow path, a plurality of flow rate measurement units are used. Since the correction is made based on the ratio of the fluid flow rates in the plurality of measurement channels actually measured, even if the ratio of the fluid flow rates in the plurality of measurement channels fluctuates over time, the fluid in the internal channel The flow rate can be obtained with high accuracy, and the presence or absence of gas leakage can be appropriately determined when the shut-off valve is opened again.

Further features of the ultrasonic gas meter according to the present invention are as follows:
Each of the plurality of measurement flow paths is divided into a plurality of parallel divided flow paths in the flow path by the partition plate,
Each of the pair of ultrasonic transmission / reception means is provided so as to be able to transmit ultrasonic waves to the plurality of divided flow paths and receive ultrasonic waves from the plurality of divided flow paths.

According to the above characteristic configuration, each of the plurality of measurement flow paths is divided into a plurality of parallel divided flow paths in the flow path by the partition plate. A plurality of divided flow paths each having a large ratio (ratio of flow path width to height) can be formed into a multilayer flow path.
Then, the ultrasonic waves are alternately transmitted from the pair of ultrasonic transmission / reception means to the plurality of divided flow paths, and the ultrasonic waves alternately received by the pair of ultrasonic transmission / reception means are received by the pair of ultrasonic transmission / reception means. Based on the signal, the flow rate of the fluid flowing through the measurement channel is measured.
In other words, the flow state of the fluid flowing through each divided flow path can be made laminar by flowing the flow measurement target fluid through a plurality of divided flow paths each having a large aspect ratio. Measurement accuracy can be improved.
Accordingly, it is possible to more appropriately determine the presence or absence of gas leakage when the shut-off valve is opened again.

Further features of the ultrasonic gas meter according to the present invention are as follows:
A flow rate measurement unit is configured comprising a measurement flow channel forming body that forms the measurement flow channel and the pair of ultrasonic transmission / reception means,
An upstream connecting portion that can be connected in communication with an upstream flow path forming body that forms an upstream end portion of the internal flow path with respect to the measurement flow path in the internal flow path. A plurality of upstream headers and a downstream end of the measurement flow path forming body are connected to a downstream flow path forming body that forms a portion of the internal flow path downstream from the measurement flow path. A downstream header having a predetermined number of possible downstream connections is provided.

According to the above characteristic configuration, the upstream end of the measurement flow path forming body of each flow rate measurement unit communicates with the upstream connection of the upstream header, and the downstream end communicates with the downstream connection of the downstream header. In a connected form, a plurality of predetermined number of flow rate measurement units can be assembled to the ultrasonic gas meter.
That is, in such an ultrasonic gas meter, it is necessary to prepare various types of fluid flow rates having different upper limit values, that is, different flow rate measuring capabilities.
According to this characteristic configuration, the number of flow measurement units is determined according to the target flow measurement capability, and the upstream connection portion in the upstream header and the downstream in the downstream header corresponding to the number of flow measurement units By setting the number of the side connection portions, various ultrasonic gas meters having different flow rate measurement capabilities can be prepared.
And since it can respond to increase / decrease in flow measurement capability using the flow measurement unit of the same specification, various ultrasonic type gas meters in which flow measurement capability differs can be prepared, achieving cost reduction. In addition, since the flow rate measurement unit having the same specification is used, it is possible to cope with an increase or decrease in the flow rate measurement capability without reducing the flow rate measurement accuracy.
In short, it is possible to make various types of ultrasonic gas meters capable of appropriately determining whether or not there is a gas leak when the shut-off valve is opened again with different flow rate measuring capabilities while reducing the cost.

Longitudinal front view showing the overall schematic configuration of an ultrasonic gas meter Longitudinal left side view showing the overall schematic configuration of an ultrasonic gas meter Perspective view of the flow rate measurement unit and its surroundings in an ultrasonic gas meter Longitudinal front view of the flow rate measurement unit and its surroundings in an ultrasonic gas meter Cross-sectional plan view of flow measurement unit Block diagram showing control configuration of ultrasonic gas meter The figure which shows the flowchart of ultrasonic type gas meter control operation

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the ultrasonic gas meter is assembled by using a casing 1 having a gas inlet 2 and a gas outlet 3. It is connected in the middle of the gas supply pipe 4 that supplies the gas G to the customer. The flow rate of the gas G flowing through the gas supply pipe 4 is measured and the measured values are integrated, and the integrated value of the measured gas flow rate is displayed on the display unit 5 provided outside the casing 1. ing.

In the casing 1, one end is connected to the gas inlet 2 and the other end is connected to the gas outlet 3, and the internal flow path 20 through which the gas G to be flow-measured flows passes through the internal flow path 20. An ultrasonic flow rate measuring means M (hereinafter sometimes simply referred to as a flow rate measuring means M) for measuring the flow rate of the flowing gas G, a seismic sensor 6 and an electrical box 7 are provided.
As shown in FIG. 6, the electrical box 7 is provided with a control unit 8 (an example of a control unit) that controls the operation of the ultrasonic gas meter, a battery 9 for powering the ultrasonic gas meter, and the like. ing.
As shown in FIGS. 1, 2, and 6, the internal flow path 20 is provided with a shut-off valve 11 that can be electrically switched from an open state to a closed state, and the shut-off valve 11 in the internal flow path 20 is provided. Further, a pressure sensor 12 for detecting the pressure of the gas G is provided on the downstream side.
Further, as shown in FIGS. 2 and 6, the casing 1 is provided with a shutoff valve return detection means 13 for detecting the return of the shutoff valve 11 from the closed state to the open state.

The shut-off valve 11 is a unidirectional type that can be operated to return from the closed state to the open state. Since this unidirectional shut-off valve 11 is publicly known, detailed description and illustration thereof will be omitted and will be briefly described.
That is, the shut-off valve 11 is provided with a permanent magnet that attracts and holds the valve element at an open position that opens the flow path, a spring that returns the valve element to a closed position that closes the flow path, and a valve element that is positioned at the closed position. It comprises a valve operating shaft 11a (see FIG. 2) that can be pushed back to the open position against the force, and a coil that can generate a magnetic field that cancels the magnetic force of the permanent magnet.
That is, the shut-off valve 11 is a so-called self-holding solenoid, and can hold the valve body in the open position by the holding force of the permanent magnet in a non-energized state, and can be held in the open state. Further, by energizing the coil to weaken the attracting and holding force of the permanent magnet, the valve body can be pulled away from the open position by the urging force of the spring and held in the closed position, thereby holding the valve closed.

As shown in FIG. 2, this shut-off valve 11 is provided with its valve operating shaft 11a facing the front surface of the casing 1, and the shut-off valve 11 is formed on the front wall portion of the casing 1 from the outside of the casing 1 by an artificial operation. A valve opening return button 10 is provided so that the valve operating shaft 11a can be pushed.
Then, by pushing the valve opening return button 10, the valve operating shaft 11a is pushed, the valve body located at the closed position is pushed back to the open position side, and the shutoff valve 11 can be returned to the open state.
The shut-off valve return detection means 13 is configured to detect the return of the valve opening by detecting the movement of the shut-off valve 11 from the closed position to the open position.

  As shown in FIG. 1 and FIGS. 3 to 6, the flow rate measuring means M is disposed at a predetermined interval on the upstream side and the downstream side of the internal flow path 20 and alternately transmits ultrasonic waves. A pair of ultrasonic transmission / reception means 14 and a flow rate calculation means for driving each ultrasonic transmission / reception means 14 and amplifying a reception signal of each ultrasonic transmission / reception means 14 and calculating a gas flow rate based on the amplified reception signal 15. The pair of ultrasonic transmission / reception means 14 are disposed so as to face each other so that the ultrasonic waves transmitted from one ultrasonic transmission / reception means 14 can be received by the other ultrasonic transmission / reception means 14. Here, of the pair of ultrasonic transmission / reception means 14 provided on the upstream side of the internal flow path 20, the reference sign “u” indicating the upstream side is attached to the reference sign “14” indicating the ultrasonic transmission / reception means. The ultrasonic transmission / reception means 14u on the upstream side is provided on the downstream side of the internal flow path 20, and the reference numeral “d” indicating the downstream side is attached to the reference numeral “14” indicating the ultrasonic transmission / reception means, This is referred to as downstream ultrasonic wave transmitting / receiving means 14d.

As shown in FIGS. 1 and 3 to 5, in the present invention, a part of the internal flow path 20 is constituted by a plurality of parallel measurement flow paths 21, and each of the plurality of measurement flow paths 21. Corresponding to the above, a flow rate measuring means M is provided.
In this embodiment, the flow rate measurement unit U is configured to include a measurement flow channel forming body 30 that forms the measurement flow channel 21, a pair of ultrasonic transmission / reception means 14, and a flow rate calculation means 15.
Further, the upstream-side channel forming body 40 that forms the upstream-side channel portion 22, which is the upstream-side end portion 30 u of the measuring channel-forming body 30 in the internal channel 20 with respect to the measuring channel 21. The upstream header 42 provided with a predetermined number of upstream connection parts 41 that can be connected to each other, and the downstream end 30d of the measurement flow path forming body 30 downstream of the measurement flow path 21 in the internal flow path 20 A downstream header 52 having a predetermined number of downstream connection portions 51 that can be connected to a downstream flow path forming body 50 that forms a downstream flow path portion 23 that is a side portion is provided.

The internal flow path 20 and the flow path measurement unit U will be described in detail.
As shown in FIGS. 3 to 5, the measurement flow path forming body 30 of the flow path measurement unit U has a rectangular cross section perpendicular to the longitudinal direction (gas flow direction) and is constant in the longitudinal direction. A substantially square cylindrical measurement channel portion 30c having an inner peripheral surface, a substantially cylindrical upstream end portion 30u communicating with the upstream side of the measurement channel portion 30c, and the measurement channel The above-described downstream end portion 30d having a substantially cylindrical shape communicating with the downstream side of the portion 30c is provided.

  As shown in FIGS. 4 and 5, both ends in the width direction are airtight in the width direction both sides of the inner peripheral surface of the measurement flow path portion 30 c in the measurement flow path portion 30 c of the measurement flow path forming body 30. A plurality of (five in this embodiment) partition plates 31 that are in contact with each other are provided at equal intervals in the height direction, and the inside of the measurement flow channel portion 20c has the same width and height. It is divided into a plurality (six in this embodiment) of divided flow paths 21s. The aspect ratio (the ratio between the width and the height of the flow path) of each divided flow path 21s is set large so that the flow state of the flowing fluid can be laminarized.

As shown in FIGS. 1, 3, and 5, the upstream ultrasonic transmission / reception means 14 u has one of the plurality of divided flow paths 21 s in the width direction in the measurement flow path portion 30 c of the measurement flow path forming body 30. The ultrasonic waves can be transmitted substantially uniformly to the plurality of divided flow paths 21s toward the downstream side, and transmitted from the downstream ultrasonic transmission / reception means 14d described later. The ultrasonic waves that have passed through each of the plurality of divided flow paths 21s are provided so as to be received substantially evenly.
Further, the ultrasonic transmission / reception means 14d on the downstream side is placed on the side where the other end in the width direction of each of the plurality of divided flow paths 21s in the measurement flow path section 30c of the measurement flow path forming body 30 is positioned. The ultrasonic waves can be transmitted substantially uniformly to the plurality of divided flow paths 24 toward the upstream side, and the ultrasonic waves transmitted from the ultrasonic transmission / reception means 14u on the upstream side and passed through the plurality of divided flow paths 21s. Can be received substantially evenly.
That is, each of the plurality of measurement flow channels 21 is divided into a plurality of parallel divided flow channels 21 s in the flow channel by the partition plate 31, and each of the pair of ultrasonic transmission / reception means 14 is divided into the plurality of divided flow flows. The ultrasonic waves can be transmitted to the path 21s and the ultrasonic waves from the plurality of divided flow paths 21s can be received.
The flow rate calculation means 15 is provided on the outer peripheral portion of the measurement flow path portion 30 c in the measurement flow path forming body 30.

The maximum flow rate that can be measured by one flow path measurement unit U is set in advance, and in this embodiment, for example, is set to 10 m ³ / h (1 hour).
Then, the number of flow channel measurement units U to be provided is set according to the target maximum measurable gas flow rate so that the predetermined maximum gas flow rate can be measured. In this embodiment, the maximum measurable gas flow rate is set to 60 m ³ / h, and six flow path measurement units U are provided as shown in FIGS.

  As shown in FIG. 1, the upstream flow path forming body 40 that forms the upstream flow path portion 22 of the internal flow path 20 includes an inflow portion 43 and an upstream buffer portion 44 that are connected to communicate with each other. The downstream-side channel forming body 50 that forms the downstream-side channel portion 23 of the internal channel 20 includes a downstream-side buffer unit 54 and an outflow unit 53 that are connected to communicate with each other. A plurality of flow path measurement units U are connected in parallel between the upstream buffer unit 44 and the downstream buffer unit 54 via the upstream header 42 and the downstream header 52. And, by the inflow part 43, the upstream buffer part 44, the plurality of measurement flow path forming bodies 30, the downstream buffer part 54, and the outflow part 53, the upstream flow path part 22 is arranged in parallel from the upstream side to the downstream side. A plurality of measurement flow channels 21 and a downstream flow channel portion 23 are connected in series to form an internal flow channel 20.

As shown in FIG. 1, the gas inlet 2 and the gas outlet 3 are provided at predetermined intervals on the upper surface portion of the casing, and an approximately square cylindrical inflow portion 43 is connected to the gas inlet 2. A substantially cylindrical outlet 53 is connected to the gas outlet 3.
The upstream buffer unit 44 and the downstream buffer unit 54 are both substantially rectangular parallelepiped boxes, and the upstream buffer unit 44 and the downstream buffer unit 54 are arranged in such a manner that one side faces each other in the lateral direction. The portion 44 is connected in communication with the inflow portion 43 via its upper surface portion, and the downstream buffer portion 54 is connected in communication with the outflow portion 53 via its upper surface portion.

The upstream header 42 is provided on the side facing the downstream buffer 54 in the upstream buffer 44, and the downstream header 52 is provided on the side facing the upstream buffer 44 in the downstream buffer 54. Yes.
The upstream connection part 41 and the downstream connection part 51 are provided in the same number (six in this embodiment) as the number of the flow path measurement units U, respectively.
As shown in FIGS. 4 and 5, each upstream connection portion 41 is formed on the side surface of the upstream buffer portion 44 so as to be able to be inserted through the cylindrical upstream end portion 30 u of the measurement flow path forming body 30. A circular upstream connection hole 45 and a space between the outer peripheral portion of the upstream end 30u of the measurement flow path forming body 30 inserted through the upstream connection hole 45 and the upstream buffer section 44 are airtight. An upstream side sealing member 46 to be sealed is provided.
In addition, each downstream connection portion 51 has a circular downstream connection hole 55 formed on the side surface of the downstream buffer portion 54 so that the cylindrical downstream end portion 30d of the measurement flow path forming body 30 can be inserted. And the downstream side sealing member which seals between the outer peripheral part of the downstream edge part 30d of the flow-path formation body 30 for measurement inserted in the downstream connection hole 55, and the downstream buffer part 54 airtightly 56 etc. are comprised.

  1, 3, and 4, the downstream end 30 d of the measurement flow path forming body 30 of each flow path measurement unit U is connected to the downstream connection hole 55 of the downstream buffer section 54 upstream. In the state where the side end 30u is inserted into the upstream connection hole 45 of the upstream buffer section 44, the outer peripheral portion of the portion protruding from the upstream connection hole 45 in the upstream end 30u of the measurement flow path forming body 30 is provided. Then, the nut member 47 is tightened. Then, each flow rate measurement unit U is in a state where the upstream end of the measurement flow path forming body 30 communicates with the upstream buffer section 44 and the downstream end communicates with the downstream buffer section 54 in an airtight manner. 21 is provided between the upstream buffer unit 44 and the downstream buffer unit 54 in a posture in which the longitudinal direction of 21 is in a horizontal direction.

Next, the flow form of the fluid flowing through the internal flow path 20 configured as described above will be described.
The fluid flowing into the internal flow path 22 from the gas inlet 2 flows through the upstream flow path portion 22, flows through the plurality of parallel measurement flow paths 22, and then flows through the downstream flow path portion 23. And flows out from the gas outlet 3.
Each measurement flow path 22 is a multilayer flow path in which a plurality of divided flow paths 22s having a large aspect ratio are arranged in layers, and the fluid state of the fluid flowing through each divided flow path 22s is laminarized.
Then, ultrasonic waves are alternately transmitted from the pair of ultrasonic transmission / reception means 14 to the plurality of divided flow paths 22 s through which the fluid whose flow rate is to be measured flows in a laminar flow state, and the pair of ultrasonic transmission / reception means 14. Accordingly, the ultrasonic waves passing through the plurality of divided flow paths 22s are alternately received, and the fluid flow rate is measured based on the received signal, so that the accuracy of flow rate measurement can be improved.

Since the flow rate measuring means M is publicly known, a method in which the flow rate measuring means M measures the gas flow rate will be briefly described below.
The flow rate calculation means 15 drives the upstream ultrasonic transmission / reception means 14u and the downstream ultrasonic transmission / reception means 14d so as to alternately transmit ultrasonic waves, and the upstream ultrasonic transmission / reception means 14u and downstream ultrasonic waves. Based on the ultrasonic reception signal of each transmission / reception means 14d, the forward propagation time of the ultrasonic waves from the upstream ultrasonic transmission / reception means 14u to the downstream ultrasonic transmission / reception means 14d, and the downstream ultrasonic transmission / reception means The backward propagation time of the ultrasonic wave from 14d to the upstream ultrasonic wave transmitting / receiving means 14u is calculated.
Further, the flow rate calculation means 15 calculates the flow velocity of the fluid (gas G or the like) flowing through the measurement flow channel 21 based on the forward propagation time and the reverse propagation time, and the calculated flow velocity of the fluid. The fluid instantaneous flow rate is calculated by multiplying the cross-sectional area of the measurement channel 21.

When calculating the instantaneous flow rate of the fluid as described above, the flow rate calculation means 15 automatically amplifies the reception signals of the ultrasonic transmission / reception means 14u and 14d so as to have a magnitude within a predetermined range, An instantaneous flow rate of the fluid is calculated based on the amplified received signal.
Incidentally, when the measurement channel 21 is filled with the gas G (for example, 13A of city gas) and the fluid whose flow rate is to be measured is the gas G, the amplification degree (gain) of the reception signal of the ultrasonic transmission / reception means 14 Is about 42 to 46, for example. Also, when the measurement flow channel 21 is filled with air, such as when an ultrasonic gas meter is attached or replaced, and the fluid whose flow rate is to be measured is air, the amplification level of the received signal of the ultrasonic transmission / reception means 14 is For example, it is about 32-36.

Each of the plurality of flow rate calculation means 15 performs measurement of the instantaneous flow rate of such a fluid (for example, gas G) at a predetermined measurement cycle (for example, 2 seconds), and transmits the measured instantaneous flow rate to the control unit 8. It is configured as follows.
And the control part 8 calculates | requires the instantaneous flow volume of the internal flow path 20 by totaling the instantaneous flow volume transmitted from each of the several flow volume calculating means 15, and multiplies the measurement flow time to the instantaneous flow volume of the internal flow path 20. Thus, the periodic flow rate of the internal flow path 20 is obtained, the obtained periodic flow rates of the internal flow path 20 are integrated, and the integrated flow rate is displayed on the display unit 5.

By the way, when the shutoff valve 11 is opened and returned in a state where the internal flow path 20 is filled with air, such as when an ultrasonic gas meter is attached or replaced, the gas G is introduced from the upstream side of the internal flow path 20. Flows, and the air in the internal flow path 20 is forced to flow downstream. Therefore, between the upstream ultrasonic transmission / reception means 14u and the downstream ultrasonic transmission / reception means 14d in the measurement flow path 21. The gas-air phase coexistence state in which the gas G region and the air region coexist may appear without the gas G and air being sufficiently mixed.
As described above, when the gas / air phase coexistence state appears between the upstream ultrasonic transmission / reception means 14u and the downstream ultrasonic transmission / reception means 14d in the measurement channel 21, the gas G region and the air region Then, since the acoustic impedances are different, faults with different acoustic impedances appear in the measurement channel 21. Then, since the ultrasonic waves transmitted from the ultrasonic transmission / reception means 14u and 14d are easily reflected by the tomography having different acoustic impedances, the reception signals of the ultrasonic transmission / reception means 14u and 14d become small, and as a result, Amplification becomes larger than usual.
Therefore, the gas / air phase coexistence state can be detected based on the amplification degree of the reception signals of the ultrasonic transmission / reception means 14u and 14d. For example, when the degree of amplification is greater than 42 to 46, it can be detected that a gas-air phase coexistence state appears.

Next, the control operation of the control unit 8 will be described.
The control unit 8 detects an abnormality on the basis of the measurement information of the flow rate measuring means M, executes an abnormal-time cutoff process for switching the cutoff valve 11 to a closed state when the abnormality is detected, and returns the cutoff valve. When the detection means 13 detects that the shut-off valve is opened again, it is configured to execute a return-time leak determination process for determining whether or not a gas leak has occurred downstream from the shut-off valve 11. Yes.
Further, the control unit 8 is configured to execute the abnormal interruption process even when an abnormal vibration is detected by the seismic sensor 6.

In the present invention, the control unit 8 is configured to detect an abnormality based on the fluid flow rate measured by the plurality of flow rate measuring means M provided in each of the plurality of measurement flow paths 21, and In the return leakage determination process, the fluid flow rate of the internal flow path 20 is determined based on the fluid flow rate measured by the flow rate measurement means M whose received signal amplification is equal to or less than the set amplification level. It is configured to determine whether or not gas leakage has occurred based on the fluid flow rate of 20.
In addition, in the return leakage determination process, the control unit 8 regards that the fluid flow rate in the internal flow path 20 is zero when the amplification levels of the reception signals of all the plurality of flow rate measurement means M are larger than the set amplification level. Thus, it is configured to determine whether or not gas leakage has occurred.
Here, the set amplification degree Zs is larger than the amplification degree when the fluid whose flow rate is to be measured is gas G or air, and corresponds to a state where a gas-air phase coexistence state appears in the measurement channel 21. The amplification degree is set, and in this embodiment, for example, 50 is set.

  When the control operation of the control unit 8 is described, the control unit 8 obtains the instantaneous flow rate of the internal flow path 20 as described above based on the instantaneous flow rate transmitted from each of the plurality of flow rate calculation means 15, and the internal flow rate is determined. An abnormality is detected based on the instantaneous flow rate of the path 20. For example, the time during which the instantaneous flow rate in the internal flow path 20 becomes excessive or the state where the instantaneous flow rate in the internal flow path 20 is greater than zero, that is, the time during which the gas G continues to flow is abnormally long. It is configured to detect an abnormality based on detecting this.

  In the return leakage determination process, the control unit 8 determines the amplification level of the received signal when the amplification level of the reception signal in at least one of the flow rate calculation means 15 is equal to or less than the set amplification level. Is calculated based on the instantaneous flow rate transmitted from the flow rate calculation means 15 that is less than or equal to the set amplification degree, and the instantaneous flow rate of the internal flow path 20 is obtained, and gas leakage occurs based on the obtained instantaneous flow rate of the internal flow path 20. It is configured to determine whether or not.

Specifically, the control unit 8 sums up the instantaneous flow rates transmitted from all of the plurality of flow rate calculation units 15 when the amplification levels of the reception signals of all of the plurality of flow rate calculation units 15 are equal to or less than the set amplification level. The instantaneous flow rate of the internal flow path 20 is determined.
Further, when the amplification degree of the reception signal of some of the flow rate calculation means 15 among the plurality of flow rate calculation means 15 is equal to or less than the set amplification level, the control unit 8 determines that the amplification level of the reception signal is equal to or less than the set amplification level. The total of the instantaneous flow rates transmitted from the flow rate calculation means 15 is equal to or less than the set amplification level when the received signals of all the flow rate calculation means 15 at the time of abnormality determination causing the leakage determination process at the time of return are set. The instantaneous flow rate of the internal flow path 20 is obtained by performing correction based on the ratio of instantaneous flow rates transmitted from each of the plurality of flow rate calculation means 15.

  In other words, when the control unit 8 determines that the received signal amplification degree of a part of the flow rate measuring means M among the plurality of flow rate measuring means M is less than or equal to the set amplification degree in the return leakage determination process, the amplification of the received signal is performed. The fluid flow rate measured by the flow rate measuring means M whose degree is less than or equal to the set amplification degree is measured by each of the plurality of flow rate measurement means M when the amplification levels of the received signals of all the plurality of flow rate measurement means M are less than or equal to the set amplification degree. By correcting based on the ratio of the measured fluid flow rate, the fluid flow rate of the internal flow path 20 is obtained.

Further description will be given of the leakage determination process at the time of return.
The control unit 8 converts the instantaneous flow rate of the internal flow path 20 obtained for each measurement cycle and derives the flow rate Q per hour, and the average value of the flow rate Q per hour (hereinafter, Qave) is derived. Here, the flow rate Q per hour from the first time to the i-th time is defined as Q (1), Q (2), ..., Q (i).

  Qave = [Q (1) + Q (2) +,..., + Q (i)] / (i) (Equation 1)

  Then, when the flow rate average value Qave becomes larger than the leakage determination flow rate K during the flow rate determination setting time T1, the control unit 8 determines that gas leakage has occurred, and the flow rate determination setting time T1 In the meantime, if the state where the flow rate average value Qave is equal to or less than the leakage determination flow rate K continues, it is determined that no gas leakage has occurred. Here, the flow rate determination setting time T1 is set to, for example, 2 minutes, and the leakage determination flow rate K is set to a flow rate value per hour, for example, 50 liters / h.

Next, based on the flowchart shown in FIG. 7, the control operation in the return leakage determination process of the control unit 8 will be described.
An abnormality is detected based on the measurement information of the flow rate measuring means M by the control unit 8 when an abnormality occurs in the gas consumption at a gas demand destination where the gas meter G has already been installed and the gas G is consumed. If it does, the cutoff process at the time of abnormality will be performed, the cutoff valve 11 will be closed, and the information which shows that abnormality which may have gas leakage has occurred will be displayed on the display part 5. FIG. The resident of the gas demand destination checks the gas appliance and solves the problem, and then presses the valve opening return button 10 to return the shutoff valve 11 to open.
Also, when an operator of a gas company newly installs or replaces an ultrasonic gas meter, after installing the ultrasonic gas meter, press the valve opening return button 10 to return the shutoff valve 11 to open. Let

As shown in FIG. 7, when the shut-off valve return detecting means 13 detects that the shut-off valve 11 has returned to the open state, the control unit 8 waits for the set standby time to elapse and then starts a timer to measure. The measured pressure Pi of the pressure sensor 12 is read every cycle, and the measured pressure Pi is compared with a preset standard pressure Pn (steps # 1 to # 5).
When the measured pressure Pi becomes equal to or higher than the standard pressure Pn before the pressure determination set time T2 elapses (in the case of Yes in step # 4), the gas of the gas appliance connected to the gas supply pipe 4 at the gas demand destination Since it is considered that the stopper is closed, the return leakage determination process is continued. On the other hand, if the measured pressure Pi does not exceed the standard pressure Pn even after the set time T2 for pressure determination elapses (in step # 5). In the case of Yes), since there is a possibility that the gas plug of the gas demand destination is opened, the process proceeds to Step # 14, the shut-off valve 11 is switched to the closed state, and further, the display unit 5 indicates that an abnormality has occurred. Information to be displayed (hereinafter may be described as abnormality occurrence information) is displayed (step # 15).
Note that the set standby time is slightly longer than the time required for the standard pressure Pn to be applied downstream from the shutoff valve 11 by the gas G supplied after the shutoff valve 11 is opened. The time is set to 2 seconds, for example. The standard pressure Pn is set to a pressure slightly lower than the standard pressure applied by the supplied gas G, for example, 1 kPa, when there is no gas leakage downstream from the shut-off valve 11, and is used for pressure determination. The set time T2 is set to 90 seconds, for example.

  When it is determined in step # 4 that the measured pressure Pi is equal to or higher than the standard pressure Pn, the control unit 8 starts the timer and then derives the flow average value Qave and the derived flow average value for each set period. The process of comparing Qave with the leakage determination flow rate K is repeated (steps # 6 to # 11). Specifically, when the amplification factor Z of all the received signals of the plurality of flow rate calculation means 15 is larger than the set amplification factor Zs, the instantaneous flow rate of the internal flow path 20 is regarded as zero, and the flow rate Qi per hour. Is set to zero, and the flow rate average value Qave is derived. On the other hand, when the amplification degree Z of the reception signal of at least one flow rate calculation means 15 among the plurality of flow rate calculation means 15 is equal to or less than the set amplification degree Zs, the above is performed. Thus, the instantaneous flow rate of the internal flow path 20 is obtained and the flow rate Qi per hour is derived to derive the flow rate average value Qave.

  When the flow rate determination set time T1 elapses and the flow rate average value Qave is maintained to be equal to or less than the leakage determination flow rate K, it is determined that no gas leakage has occurred (Yes in step # 12). ), Information indicating that the shut-off valve 11 has been normally opened is displayed on the display unit 5 (step # 13), the process returns, and on the other hand, until the set time T1 for determining the flow rate elapses, When the flow rate average value Qave is larger than the leakage determination flow rate K and it is determined that the gas is leaking (in the case of No in step # 11), the process proceeds to step # 14, and the shutoff valve 11 is switched to the closed state. Further, the abnormality occurrence information is displayed on the display unit 5 (step # 15).

In the ultrasonic gas meter according to the present invention configured as described above, a part of the internal flow path 20 is configured by a plurality of parallel measurement flow paths 21, so that when the ultrasonic gas meter is installed, etc. Even when the gas G flows from the upstream side into the internal flow path 20 when the shutoff valve 11 is opened in a state where the internal flow path 20 is filled with air, a pair of the measurement flow paths 21 are paired. The measurement flow channel 21 in which a homogeneous fluid exists without the air phase coexisting state between the pair of ultrasonic transmission / reception units 14 is not formed between the ultrasonic transmission / reception units 14. Can exist.
In the return leakage determination process, the internal flow path 20 is based on the fluid flow rate of the measurement flow path 21 that is accurately measured by the flow rate measurement means M whose received signal amplification degree Z is equal to or less than the set amplification degree Zs. Is required with high accuracy.
Moreover, each of the plurality of measurement channels 21 is a multi-layered channel in which a plurality of divided channels 22s having a large aspect ratio are arranged in layers, and the flow state of the fluid flowing through each divided channel 22s is Since it is laminarized, the measurement accuracy of the fluid flow rate of the internal flow path 20 can be improved also by this.
Therefore, since it is determined whether or not gas leakage has occurred based on the fluid flow rate of the internal flow path 20 determined with high accuracy, the determination can be made appropriately.

Further, when the amplification factor Z of the received signals of all the plurality of flow rate measuring means M is larger than the set amplification factor Zs, the gas and air inside the plurality of measurement flow paths 21 flow completely or almost downstream. Therefore, it can be considered that all of the plurality of measurement flow paths 21 are in the gas / air phase coexistence state.
When the amplification factor Z of all the received signals of the plurality of flow rate measuring means M is larger than the set amplification factor Zs, it is considered that the fluid flow rate in the internal flow path 20 is zero, and whether or not gas leakage has occurred. Therefore, a part of the plurality of measurement flow paths 21 is in a gas / air phase coexistence state, all are in a gas / air phase coexistence state, or all are not in a gas / air phase coexistence state. It is possible to appropriately determine whether or not a gas leak has occurred regardless of whether or not a fluid is present.

[Another embodiment]
Next, another embodiment will be described.
(A) When the amplification level of the reception signal of a part of the flow rate measurement means M among the plurality of flow rate measurement means M is equal to or less than the set amplification level, the amplification level of the reception signal is obtained when obtaining the fluid flow rate in the internal flow path 20. May be obtained by correcting the fluid flow rate measured by the flow rate measuring means M having a predetermined amplification degree or less based on the ratio of the fluid flow rates in the plurality of predetermined measurement channels 21.
For example, when the fluid flow rates of all of the plurality of measurement flow channels 21 are configured to be the same, the number of flow rate measurement means M and the number of total flow rate measurement means M whose received signal amplification level is equal to or less than the set amplification level. The fluid flow rate of the internal flow path 20 is obtained by correcting with the ratio.

(B) In order to configure a part of the internal flow path 20 with the plurality of parallel measurement flow paths 21, in the above embodiment, the upstream flow path forming body 40 and the downstream flow path forming body 50 Although a plurality of flow rate measurement units U including separate measurement flow path forming bodies 30 are assembled, the plurality of measurement flow path forming bodies 30 are connected to the upstream flow path forming body 40 and the downstream flow path forming body. It is good also as a structure integrally connected to 50 in parallel.

(C) In the above embodiment, each of the plurality of measurement flow paths 21 is divided into the plurality of parallel divided flow paths 21 s in the flow path by the partition plate 31, but each of the plurality of measurement flow paths 21 is divided. It is good also as a structure which is not divided | segmented into several division | segmentation flow paths 21s.

(D) The number of installed flow channels 21 for measurement (in the above embodiment, the number of installed flow channel measurement units U) is not limited to the six illustrated in the above embodiment, but the target flow rate It can set suitably according to measurement capability.

(E) The present invention can be applied to various ultrasonic gas meters other than the ultrasonic gas meter whose flow measurement target is city gas such as 13A exemplified in the above embodiment. The present invention can be applied to a target ultrasonic gas meter.

  As described above, it is possible to provide an ultrasonic gas meter that can appropriately determine the presence or absence of gas leakage when the shutoff valve is opened again.

8 Control unit (control means)
11 shutoff valve 13 shutoff valve return detection means 14 ultrasonic transmission / reception means 20 internal flow path 21 measurement flow path 21s split flow path 30 measurement flow path forming body 30d downstream end 30u upstream end 31 partition plate 40 upstream Channel formation body 41 Upstream side connection part 42 Upstream header 50 Downstream side channel formation body 51 Downstream side connection part 52 Downstream header G Gas M Ultrasonic flow measurement means U Flow measurement unit

Claims (5)

An internal flow path through which gas for flow rate measurement flows,
Provided with a pair of ultrasonic transmission / reception means that are arranged at predetermined intervals on the upstream side and the downstream side of the internal flow path and alternately transmit ultrasonic waves, and receive signals of the pair of ultrasonic transmission / reception means respectively An ultrasonic flow rate measuring means for measuring the gas flow rate by amplifying and calculating the gas flow rate based on the amplified received signal;
A shut-off valve provided in the internal flow path and electrically switchable from a valve-open state to a valve-closed state;
A shut-off valve return detecting means for detecting a return of the shut-off valve from the closed state to the open state;
An abnormality is detected based on the measurement information of the flow rate measuring means, and when the abnormality is detected, a shut-off process at the time of switching the shut-off valve to the closed state is executed, and the shut-off valve return detecting means A control means configured to execute a return-time leakage determination process for determining whether or not a gas leak has occurred downstream of the cutoff valve when a valve opening return of the cutoff valve is detected; An ultrasonic gas meter comprising:
A part of the internal flow path is constituted by a plurality of parallel measurement flow paths,
Corresponding to each of the plurality of measurement channels, the flow rate measuring means is provided,
The control means is configured to detect the abnormality based on a fluid flow rate measured by a plurality of flow rate measurement means provided in each of the plurality of measurement flow paths, and the return leakage In the determination process, the fluid flow rate of the internal flow path is obtained based on the fluid flow rate measured by the flow rate measuring means whose amplification level of the received signal is equal to or less than the set amplification level, and the fluid flow rate of the internal flow path thus obtained is determined. To determine whether or not the gas leakage has occurred ,
In the leakage judgment process at the time of return, when the amplification degree of the reception signals of all the plurality of flow rate measurement means is larger than the set amplification degree, the fluid flow rate of the internal flow path is zero. regarded, the ultrasonic gas meter to determine whether the gas leakage has occurred. In the leakage judgment process at the time of return, when the amplification degree of the reception signal of a part of the plurality of flow measurement means is equal to or less than the set amplification degree, the amplification degree of the reception signal Is a flow rate of fluid measured by the flow rate measuring means below the set amplification level, and each of the plurality of flow rate measurement means when the amplification levels of the received signals of all the plurality of flow rate measurement means are below the set amplification level. The ultrasonic gas meter according to claim 1, wherein the ultrasonic gas meter is configured to obtain a fluid flow rate of the internal flow path by performing correction based on a ratio of measured fluid flow rates. An internal flow path through which gas for flow rate measurement flows,
Provided with a pair of ultrasonic transmission / reception means that are arranged at predetermined intervals on the upstream side and the downstream side of the internal flow path and alternately transmit ultrasonic waves, and receive signals of the pair of ultrasonic transmission / reception means respectively An ultrasonic flow rate measuring means for measuring the gas flow rate by amplifying and calculating the gas flow rate based on the amplified received signal;
A shut-off valve provided in the internal flow path and electrically switchable from a valve-open state to a valve-closed state;
A shut-off valve return detecting means for detecting a return of the shut-off valve from the closed state to the open state;
An abnormality is detected based on the measurement information of the flow rate measuring means, and when the abnormality is detected, a shut-off process at the time of switching the shut-off valve to the closed state is executed, and the shut-off valve return detecting means A control means configured to execute a return-time leakage determination process for determining whether or not a gas leak has occurred downstream of the cutoff valve when a valve opening return of the cutoff valve is detected; An ultrasonic gas meter comprising:
A part of the internal flow path is constituted by a plurality of parallel measurement flow paths,
Corresponding to each of the plurality of measurement channels, the flow rate measuring means is provided,
The control means is configured to detect the abnormality based on a fluid flow rate measured by a plurality of flow rate measurement means provided in each of the plurality of measurement flow paths, and the return leakage In the determination process, the fluid flow rate of the internal flow path is obtained based on the fluid flow rate measured by the flow rate measuring means whose amplification level of the received signal is equal to or less than the set amplification level, and the fluid flow rate of the internal flow path thus obtained is determined. To determine whether or not the gas leakage has occurred,
In the leakage judgment process at the time of return, when the amplification degree of the reception signal of a part of the plurality of flow measurement means is equal to or less than the set amplification degree, the amplification degree of the reception signal Is a flow rate of fluid measured by the flow rate measuring means below the set amplification level, and each of the plurality of flow rate measurement means when the amplification levels of the received signals of all the plurality of flow rate measurement means are below the set amplification level. by correcting on the basis of the ratio of the fluid flow rate measured, the ultrasonic gas meter that is configured to determine the fluid flow rate of the internal passage. Each of the plurality of measurement flow paths is divided into a plurality of parallel divided flow paths in the flow path by the partition plate,
Each of the pair of ultrasonic transmission / reception means is provided so as to be able to transmit ultrasonic waves to the plurality of divided flow paths and receive ultrasonic waves from the plurality of divided flow paths. The ultrasonic gas meter according to Item 1. A flow rate measurement unit is configured comprising a measurement flow channel forming body that forms the measurement flow channel and the pair of ultrasonic transmission / reception means,
An upstream connecting portion that can be connected in communication with an upstream flow path forming body that forms an upstream end portion of the internal flow path with respect to the measurement flow path in the internal flow path. A plurality of upstream headers and a downstream end of the measurement flow path forming body are connected to a downstream flow path forming body that forms a portion of the internal flow path downstream from the measurement flow path. The ultrasonic gas meter according to any one of claims 1 to 4, wherein a downstream header having a predetermined number of possible downstream connections is provided.

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