JP2021099260A - Gas meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas meter capable of detecting replacement of a gas container. SOLUTION: In a gas meter 1 connected to the downstream of a switching valve 3 for switching a plurality of gas containers 2, a measurement flow path 101 through which gas flows and a pair of ultrasonic transmission / reception arranged upstream and downstream of the measurement flow path 101. A device (first ultrasonic transmitter / receiver 102, second ultrasonic transmitter / receiver 103), a propagation time measuring unit 111 that measures the propagation time of a pair of ultrasonic transmission / reception periods, and a propagation time measured by the propagation time measuring unit 111. A flow rate calculation unit 112 that calculates the gas flow rate based on the above, and a gas container replacement detection unit 114 that detects that the gas container 2 has been switched by the switching valve 3 when the propagation time changes by a predetermined value or more during a predetermined time. To be equipped with. [Selection diagram] Fig. 2

Description

The present disclosure relates to a gas meter that measures a gas flow rate using ultrasonic waves, and more particularly to a gas meter having a function of detecting replacement of a gas container.

Patent Document 1 discloses a gas measuring device that resets an integrated value of a gas remaining amount monitoring function. This gas measuring device includes a pressure regulator with an automatic switching function having a switching signal generating means for generating a switching signal in response to a switching operation at the time of gas container replacement, and gas combustion that consumes gas supplied from the pressure regulator. A measuring instrument for measuring the amount of gas used in the instrument and a configuration for resetting the integrated value of the gas remaining amount monitoring function by a signal from the pressure regulator are disclosed.

Japanese Unexamined Patent Publication No. 2001-174308

The present disclosure provides a gas meter capable of detecting replacement of a gas container without receiving a switching signal of the gas container from a pressure regulator having a switching function or the like.

The gas meter of the present disclosure is a gas meter connected to the downstream of a gas container, in which a measurement flow path through which gas flows, a pair of ultrasonic transmitters / receivers arranged upstream and downstream of the measurement flow path, and the pair of ultrasonic waves. A propagation time measuring unit that measures the propagation time of the transmission / reception period, a flow rate calculation unit that calculates the flow rate of the gas based on the propagation time measured by the propagation time measuring unit, and a propagation time measured by the propagation time measuring unit. It is provided with a gas container replacement detection unit that detects that the gas container has been replaced when the gas container changes by a predetermined value or more within a predetermined time. Detects that it has been replaced with a gas container.

The gas meter of the present disclosure can detect the replacement of the gas container by detecting the change in the composition of the gas due to the replacement from the almost empty gas container with the full gas container as the change in the propagation time.

A system diagram including a gas meter according to the first embodiment. Another system diagram including the gas meter in the first embodiment Block diagram of the gas meter according to the first embodiment (A) A graph showing a change in propagation time due to replacement of a gas container, and (b) a graph showing measurement timing of propagation time in the first embodiment. Graph showing the change of propagation time due to gas container replacement and gas stop when gas stops Graph showing change in propagation time when gas stops after gas container replacement Flow chart explaining the processing of the gas meter in the first embodiment

(Knowledge, etc. that was the basis of this disclosure)
When supplying gas from a gas container, a so-called LP gas cylinder, the capacity of gas that can be used is finite, so regular replacement of the gas container is essential to prevent gas shortage, and gas management companies It is necessary to replace the gas container efficiently.

Then, in order to efficiently replace the gas container, there is a gas meter having a function of monitoring the remaining amount of gas in the gas container (hereinafter referred to as a gas remaining amount monitoring function). In such a gas meter, the gas container is used. The remaining amount of gas in the gas container is estimated by integrating the amount of gas used after replacement, and when the remaining amount is low, the gas is exhausted by communicating with the gas container management company (hereinafter referred to as the gas company). I was able to replace the gas container before. In addition, the gas meter equipped with the gas remaining amount monitoring function is equipped with a manual switch that resets the integrated value for the gas remaining amount monitoring function, and when replacing the gas container, in order to reset the integrated value of the remaining amount monitoring. The operator had to operate the switch.

Also, since it is more efficient in terms of delivery to replace the gas after the remaining amount of gas becomes 0, if two gas containers are installed and the remaining amount of one gas container becomes almost 0, By providing a switching valve that automatically switches to a full gas container, it was also possible to respond by providing a grace period until replacement. However, in this case as well, a gas meter having a gas remaining amount monitoring function is used for the gas company to manage the replacement time of the gas container, and when the gas container is replaced, the integrated value of the remaining amount monitoring is reset. The operator had to operate the switch.

As described above, in order to effectively use the gas remaining amount monitoring function, the operator must manually reset the usage amount when replacing the gas container, and does not reset when replacing the gas container, or If I forgot to reset it, I couldn't monitor the remaining amount correctly.

Therefore, a method has been proposed in which a pressure regulator with a switching function having a function of emitting a signal when switching the gas container is used, and the integrated value of the gas remaining amount monitoring function of the gas meter is reset by the signal from the pressure regulator.

However, it is necessary to add a signal generation function and a communication function at the time of switching to the pressure regulator and to communicate with the gas meter, which increases the cost of the pressure regulator. Alternatively, the inventors have discovered a problem that it is necessary to provide a dedicated input terminal for the gas meter, and in order to solve the problem, they have constructed the subject matter of the present disclosure.

Hereinafter, embodiments will be described in detail with reference to the drawings. However, more detailed explanation than necessary may be omitted. For example, detailed explanations of already well-known matters or duplicate explanations for substantially the same configuration may be omitted.

It should be noted that the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.
(Embodiment 1)
Hereinafter, the first embodiment will be described with reference to FIGS. 1A to 6.
[1-1. Constitution]
FIG. 1A is a diagram showing an installed state of a gas meter according to the first embodiment of the present invention. As shown in the figure, FIG. 1A shows two gas containers 2, a switching valve 3 for switching the gas container 2, a gas meter 1, and a gas. It is composed of an appliance 4, and the gas is switched by a switching valve 3 and is supplied to the gas appliance 4 from the selected gas container 2 of the two gas containers 2 via the upstream pipe 5, the gas meter, and the downstream pipe 6. .. As the switching valve 3, there are one that detects pressure and automatically switches, and one that the operator manually switches.

FIG. 1B is a diagram showing another installation state of the gas meter according to the first embodiment of the present invention, and is different from FIG. 1A in that the operator replaces the gas container with the gas container 2 instead of the switching valve 3. The point of replacement is that the gas meter has the same function.

In the following description, of the two gas containers 2, the gas container 2 in which the remaining amount of gas is almost 0 will be referred to as an empty container 2a, and the gas container 2 filled with gas will be described separately from the full container 2b.

Further, the difference between FIGS. 1A and 1B is whether the gas container 2 is replaced automatically or manually by the switching valve 3, or the operator performs the replacement work. , Common.

FIG. 2 is a block diagram showing the configuration of the gas meter of the present embodiment. In the gas meter 1, the measurement flow path 101 through which the fluid to be measured flows, the first ultrasonic transmitter / receiver 102 and the second ultrasonic wave transmitter / receiver 102 installed in the measurement flow path 101 Transmission that drives the ultrasonic transmitter / receiver 103, the switching unit 104 that switches the transmission / reception of the first ultrasonic transmitter / receiver 102, the second ultrasonic transmitter / receiver 103, and the first ultrasonic transmitter / receiver 102 and the second ultrasonic transmitter / receiver 103. The unit 105, the receiving unit 106 that receives the received signal received by the ultrasonic transmitter / receiver on the receiving side and passes through the switching unit 104, the amplification unit 107 that amplifies the received signal to a predetermined amplitude, and the amplification unit 107 amplifies the received signal. It is provided with a reference comparison unit 108 for comparing the voltage of the received signal and the reference voltage.

Further, based on the comparison results of the reference voltage setting unit 109 and the reference comparison unit 108 that set the reference voltage to be compared by the reference comparison unit 108, and based on the results of the determination unit 110 and the determination unit 110 that determine the reference point for time measurement. , Propagation time measuring unit 111 that measures the propagation time of ultrasonic waves, flow rate calculation unit 112 that calculates the flow rate of the gas to be measured based on the propagation time measured by the propagation time measuring unit 111, and propagation time measuring unit 111. Gas container replacement detection unit 114 that detects replacement of gas container 2 based on propagation time, gas remaining amount monitoring unit 115 that monitors the remaining amount of gas container 2 by integrating the flow rate obtained by the flow rate calculation unit 112, gas A control consisting of a temperature detection unit 116 that detects the temperature of the gas, an external communication unit 117 that communicates with an external device such as a center device 7 operated by a gas company, and a microcomputer that controls the entire system. The means 113 is provided.

[1-2. motion]
Next, the operation of the gas container exchange detection unit 114 in the present embodiment will be described.

[1-2-1. Operation when gas is flowing continuously]
FIG. 3A is a diagram showing a change in the propagation time of ultrasonic waves due to replacement of the gas container 2 in a state where a constant flow rate of gas is flowing, and FIG. 3B is a diagram showing a measurement timing of the propagation time.

In FIG. 3A, the Td shown by the dotted line is the change in the propagation time (hereinafter referred to as the downstream propagation time Td) from the first ultrasonic transmitter / receiver 102 to the second ultrasonic transmitter / receiver 103, and is indicated by the alternate long and short dash line. Tu is the change in propagation time (hereinafter referred to as upstream propagation time Tu) from the second ultrasonic transmitter / receiver 103 to the first ultrasonic transmitter / receiver 102, and Tdu shown by the solid line is the downstream propagation time Td and upstream side. The average value of the propagation time Tu (hereinafter referred to as the average propagation time Tdu) is shown.

Further, in FIG. 3A, with respect to the downstream propagation time Td1 and the upstream propagation time Tu1 before the gas container replacement from the empty container 2a to the full container 2b, after the gas container replacement timing A, before the gas container replacement. The downstream propagation time Td2 and the upstream propagation time Tu2 are shortened by the respective propagation time differences ΔT1 and ΔT2, but this depends on the gas flow velocity. Therefore, the flow rate calculation unit 112 can obtain the flow rate of the gas by the propagation time differences ΔT1 and ΔT2, and multiply the obtained flow rate by the flow path cross-sectional area and the flow coefficient.

Further, when the empty container 2a is switched to the full container 2b, the propagation time of the ultrasonic wave is shortened by the change time t (t = Tu1-Tu2 = Td1-Td2 = Tdu1-Tdu2). This is due to the composition and sound velocity of the gas filled in the gas container 2. The LP gas filled in the gas container 2 is a multi-component mixed gas such as propane, butane, and propylene, and is discharged from the gas container in the order of propylene → propane → butane.

Therefore, when the amount of gas remaining in the gas container 2 decreases, the composition of the gas changes and the proportion of butane increases, and the proportion of butane having a larger molecular weight than propylene or propane increases, so that the average molecular weight of the gas increases. .. On the other hand, the speed of sound becomes slower as the average molecular weight of the gas increases.

Therefore, when the empty container 2a is switched to the full container 2b while the gas is flowing, the average molecular weight of the gas is switched to a smaller gas at the timing of the replacement of the gas container 2, and the sound velocity becomes faster. As shown, the propagation time of ultrasonic waves is shortened.

The time T1 from the replacement timing A of the gas container 2 to the change of the propagation time measured by the propagation time measuring unit 111 of the gas meter 1 is the flow rate of the gas and the length of the upstream pipe 5 between the gas container 2 and the gas meter 1. Although it is determined by the above, it does not affect the gas container replacement detection by the change time t in the gas container replacement detection unit 114. Further, the time T2 at which the change in the propagation time ends is determined by the flow rate of the gas.

Then, the gas container exchange detection unit 114 monitors the change time t of the average propagation time Tdu, and can detect that the gas container 2 has been exchanged if it is equal to or more than a predetermined value tc determined in advance.

Specifically, as shown in FIG. 3B, the propagation time measuring unit 111 has a propagation time (downstream side propagation time Td and upstream side propagation time Tu) at intervals of a predetermined sampling period Ts (for example, 2 seconds). ) Is measured (S1 to S10) to obtain the average propagation time (TduS1 to TduS10), and the gas container exchange detection unit 114 measures S1 and S6 and measurement S2 at intervals of a predetermined time Ta (for example, 10 seconds). While monitoring the change time t, which is the difference between the average propagation times TduS1 and TduS6, the average propagation times TduS2 and TduS7, ... When the change time t', which is the difference between TduS6, is equal to or greater than a predetermined value tc, it can be detected that the gas container 2 has been replaced.

Further, a method of sequentially comparing the average value of the average propagation time Tdu obtained by a plurality of measurements for each predetermined time Ta may be used. For example, the average value Tn of the three average propagation times (TduS1, TduS2, TduS3) obtained in the measurements S1 to S3 in FIG. 3 and the three average propagation times obtained in the measurements S6 to S8 separated by a predetermined time Ta. When the difference of the average value Tm of (TduS6, TduS7, TduS8) is equal to or larger than the predetermined value tc, it may be detected that the gas container 2 has been replaced. In this case, when a measurement error of the propagation time occurs due to noise or the like. However, it is possible to prevent erroneous judgment.

Further, the propagation time to be compared is not limited to the average propagation time Tdu, and may be the downstream propagation time Td obtained by each measurement or the upstream propagation time Tu. Further, it may be detected that the gas container 2 has been replaced when the change time t is equal to or greater than the predetermined value tc a plurality of times in succession for comparison for each Ta for a predetermined time.

The predetermined time Ta and the predetermined value tc can be appropriately set depending on the composition of the LP gas filled in the gas container 2 and the time T2. The propagation time differences ΔT1 and ΔT2 are also affected by the change in gas composition, but if they are sufficiently smaller than the propagation time (downstream propagation time Td, upstream propagation time Tu), ΔT1 = ΔT2 and the measured flow rate. Does not change.

[1-2-2. Operation when gas stops for a short time after replacing the gas container]
Next, a detection method by the gas container replacement detection unit 114 when the gas is stopped after the replacement of the gas container 2 by the operator or the switching valve 3 will be described.

In FIG. 4, the gas is stopped immediately after the gas container 2 is replaced, or after the gas container 2 is replaced while the gas is stopped, the gas is restarted at a larger flow rate than before the stop. It shows the change of the propagation time of the ultrasonic wave when the gas flows, and the downstream side propagation time Td and the upstream side propagation time Tu are the same in the gas stop period. In FIG. 4, the same reference numerals as those in FIG. 3 are the same as those in FIG. 3, and the description thereof will be omitted.

As shown in FIG. 4, when the gas container 2 is replaced at the replacement timing B of the gas container 2 before the gas is stopped and the gas in the full container 2b has not reached the gas meter yet, the gas flows again and the above-mentioned is performed after the time T4. As described above, the gas meter 1 detects a change in the propagation time due to a change in the composition of the gas. The propagation time difference ΔT1 after the stop is larger than the propagation time difference ΔT2 after the restart depending on the flow rate.

Further, FIG. 4 shows a change in the propagation time in a state where the stop period is short and the gas in the empty container 2a and the gas in the full container 2b are not mixed. In this case, the gas container replacement detection unit 114 uses FIG. The replacement of the gas container 2 can be detected by the method described above.

Further, when the downstream propagation time Td or the upstream propagation time Tu is used, it is necessary to consider the flow rate, but when the average propagation time Tdu is used, the flow rate of the gas is not changed. Therefore, by using the average propagation time Tdu, it is possible to detect the replacement of the gas container 2 even if the gas flow rate changes during the predetermined time Ta.

[1-2-3. Operation when gas stops for a long time after replacing the gas container]
FIG. 5 shows the propagation time of ultrasonic waves when the gas is stopped for a long time after the gas container 2 is replaced by the operator or the switching valve 3, and then the gas flows again at a flow rate larger than the flow rate before the stop. FIG. 5A shows a state in which the gas stop period is long and the propagation time changes as the gas in the empty container 2a and the gas in the full container 2b gradually mix with each other. FIG. 5 (b) shows a state in which the propagation time changes as the gas gradually mixes after the gas stops in the middle of the change in the gas composition due to the replacement of the gas container 2. In FIG. 5, the same reference numerals as those in FIG. 4 are the same as those in FIG. 4, and the description thereof will be omitted. The following description can be applied even when the same flow rate as before the stop or a smaller flow rate flows after the stop.

As shown in FIG. 5A, when the gas container 2 is replaced at the gas container replacement timing B before the gas is stopped, the gas in the full container 2b has not yet reached the gas meter 1 immediately after the gas is stopped. However, when the gas stop period is long, the composition of the gas in the gas meter 1 also changes, and the propagation time measured by the propagation time measuring unit 111 gradually changes and becomes shorter.

Therefore, in the above-mentioned detection by the predetermined time Ta (for example, 10 seconds), the change time t'is obtained in the propagation time measured immediately after the gas flow is restarted, and the gas container 2 is replaced. Nevertheless, there is a possibility that a change of a predetermined value tc or more cannot be detected. In the case of a change as shown in FIG. 5B, if the change time t ″ measured during the replacement can detect a predetermined value tc or more, the replacement of the gas container 2 can be detected.

Therefore, the gas container exchange detection unit 114 determines that the gas has stopped when the downstream propagation time Td measured by the propagation time measurement unit 111 for each sampling cycle Ts and the upstream propagation time Tu match, and stops the gas. The average propagation time Tdu1 obtained by the measurement before the time Tb of the determination is stored.

After that, the gas container exchange detection unit 114 monitors the downstream propagation time Td and the upstream propagation time Tu obtained for each sampling period Ts, and when the propagation time difference ΔT becomes a value corresponding to the gas flow rate equal to or higher than the predetermined flow rate. It is determined that the gas flow has resumed, and the change time t is calculated. The stop / restart of the gas flow may be determined based on the flow rate calculated by the flow rate calculation unit 112.

At this time, the time T4 is too short to measure in the sampling cycle Ts, or it may not be possible to measure, but the average propagation time Tdu1 stored at the stop time from the restart of the flow until the predetermined time Ta elapses. By comparing with the average propagation time Tdu2 obtained by the new measurement, the gas container 2 is replaced when the change time t becomes a predetermined value tc or more after the change of the propagation time due to the change in the composition of the gas is completed. Can be detected.

If the change time t does not exceed the predetermined value tc by the time the predetermined time Ta elapses, the detection method described with reference to FIG. 3 is based on the assumption that the gas container 2 was not replaced before or during the stop of the gas. Execute.

Further, even if the gas container 2 is replaced at the gas container replacement timing C after the gas is stopped, the same determination can be made. Further, this method is also applicable to the gas shutdown described in FIG.

Further, since the sound velocity of gas is affected by the temperature, the gas container replacement detection unit 114 corrects the propagation time measured by the propagation time measuring unit 111 using the temperature of the gas detected by the temperature detecting unit 116. You can also do it. Especially when the gas is stopped for a long time, the temperature of the gas may change during the stop, so the average propagation time Tdu1 stored at the time of the stop is corrected to the propagation time of the reference temperature based on the temperature of the gas at that time. The average propagation time Tdu2 measured after the gas flow is restarted is also corrected to the propagation time of the reference temperature based on the temperature of the gas at the time of measurement, the propagation time difference is obtained, and the predetermined value tc at the reference temperature is obtained. You may compare.

Further, since the predetermined value tc is affected by the temperature of the gas, the gas container exchange detection unit 114 corrects the predetermined value tc, which is the determination value of the change time of the propagation time, with the temperature of the gas to replace the gas container. Detection accuracy can be improved.

Further, the gas container replacement detection unit 114 calculates the pressure inside the gas container by a known formula using the propagation time measured by the propagation time measurement unit 111 and the temperature detected by the temperature detection unit 116, and the pressure inside the gas container is calculated. It can also be detected that the gas container has been replaced when the value changes by a predetermined value or more.

For example, the butane concentration of the gas can be calculated from the propagation time and the temperature based on a known formula, and the pressure inside the gas container can be calculated from the correlation between the butane concentration and the pressure inside the gas container 2. Therefore, the replacement of the gas container 2 can be detected by changing the pressure (increasing the pressure) when the gas container 2 is replaced from the empty container 2a to the full container 2b.

Further, the gas container replacement detection unit 114 detects that the gas container 2 has been replaced when the propagation time changes by a predetermined value or more and the pressure inside the gas container changes by a predetermined value or more, so that the detection accuracy is further improved. improves.

Further, if the gas container replacement detection unit 114 detects the replacement of the gas container 2 and the integrated value of the gas remaining amount monitoring unit 115 is reset, it is not necessary to manually reset the remaining amount of the gas container. Management can be performed reliably.

Further, when the gas container replacement detection unit 114 detects the replacement of the gas container 2, the external communication unit 117 notifies the center device 7 or the like, so that the gas company can schedule the delivery of the gas container 2. It can be used as a reference for determining priorities, etc. when assembling. Further, even though there is still a remaining amount of gas before the replacement of the gas container 2, it is not necessary to replace the gas container 2 in a probable manner, and the delivery efficiency is improved.

[1-2-5. A series of operation explanations using a flowchart]
Next, the operation of the gas container exchange detection unit 114 described above will be described with reference to the flowchart shown in FIG.

First, the propagation time measurement unit 111 determines whether or not it is a sampling period (S100), and if it is a sampling period (Yes in process 100), measures the propagation time (S101), obtains the average propagation time Tdu, and obtains the average propagation time Tdu in chronological order. Save (S102). If it is determined that the sampling cycle is not (No in process 100), the process is exited.

Next, it is determined whether or not the gas has stopped (S103), and in the case of the first stop determination (Yes in the process S103), the average propagation time Tdu stored before the time Tb is stored as Tdu1'(S104). If it is not the first stop determination (No in process S103), it is determined whether the gas is stopped (S105), if the gas stop is continued (Yes in process S105), if the process is exited and it is not stopped. (No in process 105), it is determined whether or not the gas flow has resumed (S106), and in the case of restart (Yes in process S106), it is determined whether or not Ta has elapsed from the restart (S108), and the predetermined time Ta is If it has not elapsed (No in process S108), Tdu1'stored at the time of stop determination is substituted as the previous average propagation time Tdu1 used for the calculation of the change time (S109).

When the gas flow is not restarted (No in process S106), Tdu (Ta) stored before a predetermined time Ta is substituted as the previous average propagation time Tdu1 used for calculating the change time (S107).

Then, the change time t is obtained (S110), it is determined whether or not it is equal to or greater than the predetermined value tc (S111), and if it is equal to or greater than the predetermined value (Yes in processing S111), it is determined that the gas container is replaced (S112).

Further, when the gas container is replaced, the integrated value of the gas remaining amount monitoring unit 115 is reset (S113), and the external communication unit 117 notifies the center device 7 or the like of the gas exchange detection to the gas company. Notify (S114).

The process S113 (reset the integrated value of the gas remaining amount monitoring unit 115) and the process S114 (notification to the center device 7 and the like) may be appropriately selected according to the installation situation.

[1-3. Effect, etc.]
As described above, in the present embodiment, the gas meter 1 includes a measurement flow path 101 through which gas flows and a pair of ultrasonic transmitters / receivers (first ultrasonic transmitter / receiver 102) arranged upstream and downstream of the measurement flow path 101. , The second ultrasonic transmitter / receiver 103), the propagation time measuring unit 111 that measures the propagation time of the pair of ultrasonic transmission / reception periods, and the flow rate that calculates the gas flow rate based on the propagation time measured by the propagation time measuring unit 111. It includes a calculation unit 112 and a gas container replacement detection unit 114 that detects that the gas container 2 has been replaced when the propagation time measured by the propagation time measurement unit 111 changes by a predetermined value or more during a predetermined time.

As a result, the gas container exchange detection unit 114 gas when the change time t of the propagation time (downstream side propagation time Td, upstream side propagation time Tu, average propagation time Tdu) changes by a predetermined value tc or more between the predetermined time Ta. It can be detected that the container 2 has been replaced.

Needless to say, it is possible to detect that the gas container 2 has been replaced by using the difference in sound velocity obtained from the propagation time instead of the change time t of the propagation time.

As in the present embodiment, the gas container exchange detection unit 114 determines the propagation time when it is determined that the gas has stopped based on the propagation time measured by the propagation time measuring unit 111, and thereafter after the gas flows. After a certain period of time, the propagation time is compared with the propagation time measured by the propagation time measuring unit 111, and when the value changes by a predetermined value or more, it is detected that the gas container 2 has been replaced.

As a result, the gas container replacement detection unit 114 can detect the replacement of the gas container 2 by the change in the propagation time even when the gas is stopped after the replacement of the gas container 2.

As in the present embodiment, the gas container replacement detection unit 114 has a temperature detection unit 116 that detects the temperature of the gas, and the gas container replacement detection unit 114 is measured by the propagation time measurement unit 111 based on the temperature detected by the temperature detection unit 116. Correct the propagation time.

As a result, since the sound velocity of the gas is affected by the temperature, the propagation time can be corrected by the temperature of the gas detected by the temperature detection unit 116, and the detection accuracy is improved.

As in the present embodiment, the gas container replacement detection unit 114 has a temperature detection unit 116 that detects the temperature of the gas, and the gas container replacement detection unit 114 corrects a predetermined value tk based on the temperature detected by the temperature detection unit 116.

As a result, since the predetermined value tc is affected by the temperature, it can be corrected by the temperature of the gas detected by the temperature detection unit 116, and the detection accuracy is further improved.

As in the present embodiment, the gas container exchange detection unit 114 has a temperature detection unit 116 that detects the temperature of the gas, and the propagation time measured by the propagation time measurement unit 111 and the temperature detection unit 116 detect the gas container replacement detection unit 114. The pressure inside the gas container is calculated based on the temperature, and when the propagation time changes by a predetermined value or more during a predetermined time and the pressure inside the gas container changes by a predetermined value or more, it is detected that the gas container 2 has been replaced.

As a result, the detection accuracy is improved by detecting the replacement of the gas container 2 by both the change in the propagation time and the change in the pressure inside the gas container.

As in the present embodiment, the gas meter 1 includes a measurement flow path 101 through which gas flows, and a pair of ultrasonic transmitters / receivers (first ultrasonic transmitter / receiver 102, second ultrasonic transmitter / receiver 102, second) arranged upstream and downstream of the measurement flow path 101. The ultrasonic transmitter / receiver 103), the propagation time measuring unit 111 that measures the propagation time of the pair of ultrasonic transmission / reception periods, and the flow rate calculation unit 112 that calculates the gas flow rate based on the propagation time measured by the propagation time measuring unit 111. The pressure inside the gas container is calculated based on the propagation time measured by the temperature detection unit 116 that detects the temperature of the gas, the propagation time measured by the propagation time measurement unit 111, and the temperature detected by the temperature detection unit 116, and the pressure inside the gas container. The gas container replacement detection unit 114, which detects that the gas container 2 has been replaced when the value changes by a predetermined value or more, is provided.

As a result, as described above, the replacement of the gas container 2 can be detected only by the pressure change accompanying the replacement of the gas container 2.

As in the present embodiment, the gas container 2 has a gas remaining amount monitoring unit 115 that integrates the flow rate calculated by the flow rate calculation unit 112 from the time of switching the gas container 2, and the gas container 2 is switched by the gas container replacement detection unit 114. When it is detected, the integrated value of the gas remaining amount monitoring unit 115 is reset.

As a result, when the gas container replacement detection unit 114 detects the replacement of the gas container 2, if the integrated value of the gas remaining amount monitoring unit 115 is reset, it is not necessary to manually reset the gas container. The amount can be managed reliably.

As in the present embodiment, the external communication unit 117 that communicates with the center device 7 is provided, and when the gas container exchange detection unit 114 detects that the gas container 2 has been exchanged, the external communication unit 117 notifies the external communication unit 117.

As a result, when the gas container replacement detection unit 114 detects the replacement of the gas container 2, the external communication unit 117 notifies the center device 7 or the like, so that the gas company can deliver the gas container 2 or the like. It can be used as a reference for determining priorities when creating a schedule. Further, it is not necessary to replace the gas container 2 in spite of the remaining amount of gas before the replacement, and the delivery efficiency is improved.

Further, after confirming to the operator whether or not the gas operator resets the integrated value of the gas remaining amount monitoring unit 115 after exchanging the gas container 2 (operating the switching valve 3 or exchanging work). If the gas container 2 is replaced but the reset is forgotten, the center device 7 gives a reset instruction to the gas meter 1 to deal with the false detection of the gas remaining amount monitoring unit 115. You can also do it.

Since the above-described embodiment is for exemplifying the technique in the present disclosure, various changes, replacements, additions, omissions, etc. can be made within the scope of claims or the equivalent scope thereof.

As described above, since the gas meter according to the present invention can detect the replacement of the gas container, it is possible to improve the efficiency of the gas container replacement, recovery, and the like.

1 Gas meter 2 Gas container 7 Center device 101 Measurement flow path 102 1st ultrasonic transmitter / receiver (ultrasonic transmitter / receiver)
103 Second ultrasonic transmitter / receiver (ultrasonic transmitter / receiver)
111 Propagation time measurement unit 112 Flow rate calculation unit 114 Gas container replacement detection unit 115 Gas remaining amount monitoring unit 116 Temperature detection unit 117 External communication unit

Claims (8)

In the gas meter connected to the downstream of the gas container,
The measurement flow path through which gas flows and
A pair of ultrasonic transmitters / receivers arranged upstream and downstream of the measurement flow path,
A propagation time measuring unit that measures the propagation time of the pair of ultrasonic transmission / reception periods,
A flow rate calculation unit that calculates the flow rate of the gas based on the propagation time measured by the propagation time measurement unit, and
A gas container replacement detection unit that detects that the gas container has been replaced when the propagation time measured by the propagation time measurement unit changes by a predetermined value or more during a predetermined time.
Gas meter equipped with. The gas container exchange detection unit is the propagation time measuring unit when it is determined that the gas has stopped based on the propagation time measured by the propagation time measuring unit, and a predetermined time after the gas flows. The gas meter according to claim 1, wherein the gas meter is compared with the measured propagation time, and when the gas container changes by a predetermined value or more, it is detected that the gas container has been replaced. It has a temperature detection unit that detects the temperature of the gas.
The gas meter according to claim 1 or 2, wherein the gas container replacement detection unit corrects the propagation time measured by the propagation time measuring unit based on the temperature detected by the temperature detecting unit. It has a temperature detection unit that detects the temperature of the gas.
The gas meter according to any one of claims 1 to 3, wherein the gas container replacement detection unit corrects the predetermined value based on the temperature detected by the temperature detection unit. It has a temperature detection unit that detects the temperature of the gas.
The gas container exchange detection unit calculates the pressure inside the gas container based on the propagation time measured by the propagation time measuring unit and the temperature detected by the temperature detecting unit, and determines the propagation time during a predetermined time. The gas meter according to any one of claims 1 to 4, wherein it is detected that the gas container has been replaced when the gas container changes by a value or more and the pressure inside the gas container changes by a predetermined value or more. In the gas meter connected to the downstream of the gas container,
The measurement flow path through which gas flows and
A pair of ultrasonic transmitters / receivers arranged upstream and downstream of the measurement flow path,
A propagation time measuring unit that measures the propagation time of the pair of ultrasonic transmission / reception periods,
A flow rate calculation unit that calculates the flow rate of the gas based on the propagation time measured by the propagation time measurement unit, and
A temperature detector that detects the temperature of the gas and
The pressure inside the gas container is calculated based on the propagation time measured by the propagation time measuring unit and the temperature detected by the temperature detecting unit, and the gas container is replaced when the pressure inside the gas container changes by a predetermined value or more. The gas container replacement detection unit that detects that the gas container has been replaced,
Gas meter equipped with. It has a gas remaining amount monitoring unit that integrates the flow rate calculated by the flow rate calculation unit from the time of switching the gas container.
The gas meter according to any one of claims 1 to 6, wherein when the gas container replacement detection unit detects that the gas container has been switched, the integrated value of the gas remaining amount monitoring unit is reset. .. Equipped with an external communication unit that communicates with the center device
The gas meter according to any one of claims 1 to 7, wherein when the gas container exchange detection unit detects that the gas container has been switched, the external communication unit notifies the gas container.

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