JP7113303B2 - gas shutoff device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a gas cutoff device that measures a gas flow rate and monitors whether or not its use is safe.

Conventionally, gas shutoff devices of this type measure the gas flow rate, and when the measured gas flow rate deviates from the normal operating conditions, shut off the gas with a built-in shutoff valve and then restore, that is, cancel the shutoff. A method for confirming leakage in the event of leakage has been disclosed (see, for example, Patent Literature 1).

If the gas hose is cut off due to an abnormally large flow rate (total flow cutoff), or if the gas appliance such as a stove is used for a long time beyond the normal usage time and is cut off (use time cutoff), the gas hose will be disconnected. Until the disconnection factor is corrected by fixing the disconnection or closing the cock of the gas appliance, the raw gas in the piping will naturally escape, so immediately after opening the shutoff valve again by the return operation, There is a pressure difference with the downstream side, and a large flow rate flows until the gas pressure in the downstream side pipe, which has decreased, reaches the supply pressure. After that, when the pressure becomes uniform, the measured flow velocity becomes zero or a value close to zero.

However, if for some reason the shut-off factor is not improved and the shut-off valve is opened by performing the return operation, the flow rate becomes close to zero for a while after a large flow, but the valve of the gas appliance downstream of the pipe is opened. Therefore, when the gas is completely filled, the flow rate starts to increase gradually, and a phenomenon occurs in which the flow rate returns to the flow rate in the gas supply state immediately before the cutoff.

The leakage confirmation method described in Patent Document 1 utilizes this phenomenon to determine leakage. is detected, and if the flow rate at this time exceeds a predetermined level, it is determined that there is a leak.

JP 2006-118762 A

However, in the above-described conventional configuration, the predetermined time for detecting the flow rate after recovery is fixed at the time learned when the gas cutoff device in each customer's house is installed, so the piping state due to equipment changes in each customer's house and environmental factors. This predetermined time becomes excessive for the piping state of each customer's house and requires extra time for the restoration operation, or the predetermined time is insufficient for the piping state of each customer's house and the piping is in progress. There was a problem that the flow rate generated when the gas filled with gas was erroneously determined as a leak and a cutoff output was generated.

The present invention is intended to solve the above-mentioned conventional problems. After the gas shutoff device detects an abnormality and shuts off the gas, the shutoff is canceled by a reset operation and the gas is leaked when the valve is opened. It is an object of the present invention to provide a gas shut-off device that quickly makes a determination and monitors whether or not the state of use of a gas appliance is safe.

In order to solve the above conventional problems, the gas cutoff device of the present invention comprises a flow path through which a fluid to be measured flows, a flow rate measuring means for measuring the flow rate of the fluid to be measured flowing through the flow path, and shutting off the flow path. an abnormality determining means for blocking the flow path with the blocking means when the flow rate obtained by the flow rate measuring means is determined to be abnormal; a restoring means for canceling the blocking by the blocking means; and the restoring means After the disconnection is released, the flow rate change rate calculation means for obtaining the flow rate change rate from the flow rate measured by the flow rate measurement means, and the flow rate change rate calculated by the flow rate change detection means is judged to be equal to or less than a predetermined judgment value. Then, when the flow rate measured by the flow rate measuring means is equal to or higher than a predetermined flow rate, it is determined that there is a leak, and the blocking means blocks the flow path.

As a result, the problem that the return operation takes extra time, and the problem that the judgment value is insufficient for the piping state of each customer's house and the flow rate generated when the piping is filled with gas is mistakenly judged as a leak and shut off. Therefore, it is possible to make a leak judgment suitable for the piping condition due to equipment changes in each customer's house and environmental factors. Therefore, it is possible to make a judgment and improve usability.

According to the gas cutoff device of the present invention, there are problems that the time from the restoration means to the leakage judgment is excessive or insufficient, and the judgment value is insufficient for the piping state of each customer's house. There is no problem of erroneously judging the flow rate generated when gas fills the pipe as a leak and shutting it off. Since the time required for leak judgment can be optimized according to the piping, the judgment can be made without requiring more time than necessary, and usability can be improved.

1 is a control block diagram of a gas cutoff device according to Embodiment 1 of the present invention; Diagram for explaining the principle of flow rate measurement in flow rate measurement means Graph for explaining leakage determination in Embodiment 1 of the present invention Flowchart for explaining leakage determination in Embodiment 1 of the present invention Control block diagram of gas cutoff device according to Embodiment 2 of the present invention Graph for explaining the judgment value determination method in Embodiment 2 of the present invention Graphs for explaining the determination value determination method of another example of Embodiment 2 of the present invention Graphs for explaining the determination value determination method of another example of Embodiment 2 of the present invention

A first invention is a flow path through which a fluid to be measured flows, a flow rate measuring means for measuring the flow rate of the fluid to be measured flowing in the flow path, a blocking means for blocking the flow path, and the flow rate measuring means. Abnormality determining means for blocking the flow path with the blocking means when the flow rate is determined to be abnormal; restoring means for canceling blocking by the blocking means; a flow rate change rate calculation means for obtaining a flow rate change rate from the measured flow rate; When the flow rate is equal to or higher than a predetermined flow rate, it is determined that there is a leak, and the blocking means blocks the flow path. Issues such as the problem that it takes extra time for the recovery operation, and the problem that the judgment value is insufficient for the piping state of each consumer's house and the flow rate generated when the piping is filled with gas is mistakenly judged as a leak and shut off. Instead, it is possible to make leak judgments that are suitable for changes in the facilities of each consumer and the state of piping due to environmental factors.In addition, the time required for leak judgment can be optimized according to the piping, so judgments can be made without taking more time than necessary. Usability can be improved.

In a second aspect, in particular, in the first aspect, it comprises a judgment value setting means for setting the judgment value, and the judgment value setting means is the flow rate measured by the flow rate measuring means and/or the flow rate change rate. The determination value is set according to the flow rate change rate calculated by the calculation means, and the determination value can be optimized according to the piping state.

A third invention is characterized in that, particularly in the second invention, the judgment value setting means sets the judgment value according to the maximum flow rate immediately after the shutoff is canceled by the recovery means. .

A fourth aspect of the invention is particularly characterized in that, in the second aspect, the judgment value setting means sets the judgment value according to the rate of change in the flow rate immediately after the shutoff is canceled by the recovery means. be.

A fifth aspect of the invention is particularly characterized in that, in the second aspect, the judgment value setting means sets the judgment value according to a rate of change in the flow rate for a predetermined time after the shutoff is canceled by the return means. It is something to do.

A sixth aspect of the invention is particularly characterized in that, in the second aspect, the judgment value setting means sets the judgment value according to the flow rate when the abnormality judgment means judges an abnormality and the interruption means shuts off the flow. It is something to do.

According to a seventh invention, in particular, in the first to sixth inventions, there is provided a time measuring means for measuring time after the shutoff is canceled by the restoring means, and the leakage determination means measures a predetermined time with the time measuring means. If the flow rate change rate calculated by the flow rate change rate calculation means does not become equal to or less than the judgment value by the time the flow rate change rate is calculated, it is judged to be abnormal and the flow path is blocked by the blocking means.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.
It should be noted that the present invention is not limited by this embodiment.

(Embodiment 1)
FIG. 1 shows a control block diagram of a gas cutoff device according to an embodiment of the present invention. A blocking means 3 for blocking the flow path 1, an abnormality determination means 4 for blocking the flow path by the blocking means 3 when the flow rate obtained by the flow rate measuring means 2 is determined to be abnormal, and a return for canceling the blocking by the blocking means 3. means 5, flow rate change rate calculation means 6 for obtaining the change rate of the flow rate measured by the flow rate measurement means 2 after the interruption is canceled by the return means 5, and the change rate obtained by the flow rate change rate calculation means 6 is a predetermined judgment. After the flow rate measured by the flow rate measuring means 2 is determined to be within the value 9, it is determined that there is a leak and the flow path 1 is blocked by the blocking means 3 .

FIG. 2 shows an example of the flow rate measuring means 2. Hereinafter, the principle of flow rate measurement using ultrasonic waves will be described with reference to FIG.

The flow rate measuring means 2 includes a first ultrasonic transmitter/receiver 2a, a second ultrasonic transmitter/receiver 2b, a control circuit 2c and an arithmetic circuit 2d.

Let V be the velocity of the fluid flowing through the flow path 1, C be the velocity of sound in the fluid, and θ be the angle between the direction of flow of the fluid and the propagation direction of the ultrasonic wave until the ultrasonic wave is reflected by the lower surface 1a. Also, let L be the effective length of the propagation path of the ultrasonic wave propagating between the first ultrasonic transmitter/receiver 2a and the second ultrasonic transmitter/receiver 2b.

The control circuit 2c controls transmission of ultrasonic waves from the first ultrasonic transmitter/receiver 2a and reception of ultrasonic waves by the second ultrasonic transmitter/receiver 2b. The propagation time t1 required for the ultrasonic waves transmitted from the first ultrasonic transmitter/receiver 2a to reach the second ultrasonic transmitter/receiver 2b is expressed by the following formula.

t1=L/(C+V cos θ) (1)
The control circuit 2c controls transmission of ultrasonic waves from the second ultrasonic transmitter/receiver 2b and reception of ultrasonic waves by the first ultrasonic transmitter/receiver 2a. The propagation time t2 for the ultrasonic waves transmitted from the second ultrasonic transmitter/receiver 2b to reach the first ultrasonic transmitter/receiver 2a is given by the following formula.

t2 = L/(C-V cos θ) (2)
Eliminating the sound velocity C of the fluid from the equations (1) and (2), the following equation is obtained.

V = (L/(2cosθ)) × ((1/t1)-(1/t2)) (3)
As can be understood from the equation (3), if L and θ are known, the flow velocity V can be obtained by the control circuit 2c measuring the propagation times t1 and t2. The calculation circuit 2d calculates the flow velocity V. FIG.

Further, the arithmetic circuit 2d calculates the flow rate Q by multiplying the flow velocity V by the cross-sectional area S of the flow path 1 and the coefficient k, as shown in the following equation. Note that the cross-sectional area S is known, and the coefficient k is a correction coefficient obtained by testing.

Q = k x V x S (4)
In the above example, the so-called V-pass type flow rate measurement principle was explained, but this is just an example. Measurement principles called so-called Z pass method and I pass method may be used.

It is not essential that the flow rate measuring means 2 be ultrasonic. A known measuring instrument can be used as long as it can measure the flow rate of the fluid flowing through some of the partial flow paths. A known meter may be, for example, a thermal flow sensor that measures flow rate using heat transfer by flow. Since these are publicly known, their description is omitted.

With the configuration described above, the flow rate measuring means 2 can measure the flow rate of the fluid flowing through the flow path 1, and performs measurement at regular intervals, for example, every two seconds.

Abnormality determining means 4 determines whether or not there is an abnormal use condition from the flow rate of the gas obtained by the flow rate measuring means 2 . For example, it detects an abnormally high flow rate that occurs when a hose that supplies gas to a gas appliance such as a stove comes off for some reason, monitors the usage time of a gas appliance, and measures the maximum usage that is assumed to be used normally. It detects whether the time has passed or not, and monitors whether any abnormal usage conditions have occurred.

When an abnormality is detected by the abnormality determination means 4, the interruption means 3 shuts off the flow path 1 to stop the gas supply, thereby ensuring safety.

The return means 5 is for releasing the blockage of the flow path 1, which has been detected as abnormal by the abnormality determination means 4 and blocked by the blocking means 3, and giving a return instruction to make the gas usable again. etc.

The flow rate change rate computing means 6 computes the flow rate change rate from the flow rate detected last time by the flow rate measuring means 2 and the flow rate detected this time after the shutoff is canceled by the return means 5 .

Leak judgment means 7 compares the rate of change in flow rate with judgment value 9 by means of flow rate change rate calculation means 6, and after judging that it is within the judgment value, the flow rate measured by flow rate measurement means 2 is judged whether or not it is equal to or less than a predetermined flow rate. If the flow rate is not equal to or less than the predetermined flow rate, it is determined that leakage has occurred, and the flow path 1 is blocked again by the blocking means 3 .

The notification means 8 displays the content of the abnormality on a liquid crystal display element or the like (not shown) when the abnormality determination means 4 determines that the gas usage condition is abnormal or when the leakage determination means 7 determines that there is a leakage. At the same time, a notification is sent to the center that monitors gas safety through a telephone line or the like.

Next, the operation of this embodiment will be described using the graph of time and the flow rate measured by the flow rate measuring means 2 shown in FIG.

Fig. 3 detects an abnormality such as a disconnection of a hose during use of a gas appliance that exceeds the maximum judgment flow rate, which is set to be larger than the expected flow rate for normal use of the gas appliance, and shuts off the gas. , is a graph showing the change in gas flow rate when the shutoff is canceled by the return operation and the pipe from which the gas has escaped is filled with gas. Indicates when insufficient and leakage occurs.

First, when some abnormality is detected in the flow rate measured by the flow rate measuring means 2 (in this case, when the maximum determination flow rate is exceeded), first, the flow path 1 is blocked by the blocking means 3 (blocking A).

After that, the blocking factor is removed, for example, if the gas hose is disconnected, the gas hose is reconnected, and the return means 5 is operated to release the blocking by the blocking means 3 to open the flow path 1.例文帳に追加

After shutting off, the gas in the pipe naturally escapes until the cause of the abnormality is improved, so immediately after the shutting off, there is a pressure difference between the upstream side (supply side) and the downstream side of the shutting off means 3, and the pressure drops. Gas flows until the gas pressure in the downstream piping reaches the pressure on the supply side. After that, when the cause of the abnormality is improved, the gas flow rate detected by the flow rate measuring means 2 gradually decreases as indicated by the solid line, and when the pressure becomes uniform, it decreases to near zero. The time it takes to drop to near zero depends on the installation environment such as the length of the pipe after the meter.

Therefore, in the present embodiment, after the interruption is canceled, the leakage determining means 7 determines whether or not the flow rate change rate detected by the flow rate change rate calculating means 6 is equal to or less than the determination value. If it is determined that the rate of change in the flow rate is below a predetermined value and is stable, and if the flow rate measured by the flow rate measuring means 2 does not exceed the predetermined flow rate, the cause of the abnormality is eliminated and there is no leakage. I judge.

Conversely, if the cause of the abnormality is not eliminated and leakage occurs, a gas flow rate that asymptotically approaches the leak flow rate q is detected as indicated by the dotted line, and the leakage determination means 7 detects a change in the flow rate. If the rate is determined to be equal to or less than the judgment value, the flow rate measured by the flow rate measuring means 2 is greater than or equal to the predetermined flow rate, so it is determined that leakage has occurred for some reason, and the cutoff means 3 again cuts off the flow path. 1 is blocked (block B).

In addition, in the case of shutoff exceeding the maximum judgment flow rate due to disconnection of the gas hose, etc., if the return operation is performed without improving the cause of the abnormality, the gas exceeding the maximum judgment flow rate will flow at the same time as the interruption is released, causing an abnormality. When the determination means 4 detects an abnormality, the shutdown is executed again (shutoff C).

Next, the processing of the leakage determining means 7 in this embodiment will be described using the flowchart of FIG. It should be noted that the interruption processing by the interruption means 3 due to the judgment of abnormality by the abnormality judgment means 4 is performed by a different process, and the processing in the leakage judgment means 7 will be mainly described here.

First, the flow rate is measured by the flow rate measuring means 2 (S001), and the presence or absence of a return operation F, which will be described later, is determined. For example, it is determined whether or not there is an interruption (S003), and if it is during interruption, it is determined whether or not the reset switch has been operated (S004). A return operation F for indicating that the return operation is in progress is set (S005), a monitoring timer for monitoring the time of the return operation process is started (S006), and the interruption by the interruption means 3 is canceled (S007).

Next, the flow rate change rate calculation means 6 calculates the flow rate change rate from the previous flow rate value and the current flow rate value measured by the flow rate measurement means 2 (S008), and determines whether or not the rate of change is equal to or less than a predetermined judgment value. (S009), if it is below, it is judged that the flow rate has stabilized, the flow rate measured this time is compared with the judgment flow rate for judging leakage (S011), and if it is below the judgment flow rate, there is no leakage (S012), the return operation is terminated (S013), and when the flow rate exceeding the determination flow rate is measured, it is determined that leakage has occurred (S014) and the shutoff is performed again (S015). .

If the flow rate change rate is not equal to or less than a predetermined value in step S009, it is determined that the flow rate is not stable, and it is further determined whether or not the time measured by the monitoring timer has exceeded the monitoring time (S010). If not exceeded, the process is terminated, and if exceeded, it is determined that the flow rate is not stable, it is determined that an unpredictable abnormality has occurred, and shutoff is performed again (S015).

If no leakage is detected in the normal state by the above processing, it can be determined that the blocking factor has been eliminated, and the flow path 1 can be opened so that the gas appliance can be used normally.

After detecting an abnormality during use of the gas appliance and shutting it off in this way, a different slope (rate of change) is used according to the pipe to judge whether or not there is a gas leak after the restoration means 5 restores the shutoff means 3. By doing so, the time required for the leak determination can be optimized according to the piping, so the determination can be made without requiring more time than necessary, and usability can be improved.

(Embodiment 2)
FIG. 5 shows a control block diagram of a gas cutoff device according to Embodiment 2 of the present invention. Components having the same reference numerals as those of Embodiment 1 have the same structure and functions, and the description thereof is omitted. A difference from the first embodiment is that a judgment value setting means 10 for determining a judgment value 9 to be compared with the flow rate change rate calculated by the flow rate change rate calculation means 6 is provided.

In the first embodiment, the determination value of the rate of change in the flow rate was described as a preset value, but in the second embodiment, the determination value setting means 10 sets the maximum A judgment value is determined according to the flow rate.

Fig. 6 shows an example of the difference in the maximum flow rate immediately after the disconnection is released by the return operation and the change in the flow rate after that depending on the presence or absence of leakage. Since it takes time to stabilize, if the determination value is the same, if the maximum flow rate immediately after disconnection is released is large, it takes time to stabilize, which is not preferable. Therefore, the decision value setting means 10 sets the decision value to a larger value as the maximum flow rate immediately after the disconnection is released is larger in order to perform the leak decision at an early stage.

It is also effective to determine this determination value according to the rate of change in the flow rate immediately after the shutoff is canceled by the return means 5 .

Fig. 7 shows an example of the flow rate change depending on the presence or absence of leakage when the maximum flow rate immediately after the release of the cutoff is the same, but the rate of change in the flow rate is different. If the flow rate change rate immediately after is small, it takes time to stabilize. Therefore, if the determination value is the same, if the initial gradient is small, it takes time to stabilize, which is not preferable. Therefore, the determination value setting means 10 sets the determination value to a larger value as the rate of change in the flow rate immediately after the disconnection is released is smaller. In this case, it is possible to determine the judgment value not only by the rate of change in the flow rate immediately after the disconnection is released, but also by the magnitude of the gradient for a certain period of time.

Also, this judgment value can be determined according to the magnitude of the flow rate at the time of interruption.

Fig. 8 shows an example of the reason for shutting down (difference in flow rate at shutting down) and flow rate change after shutting down. The solid line until shutting down is when the maximum judgment flow rate is exceeded, and the dotted line is normally assumed to be a gas appliance. It shows the case of continuous use over time. As shown in the figure, the greater the flow rate at the time of shutoff, the greater the pressure drop, so the maximum flow rate immediately after the shutoff is released also increases. Therefore, it can be seen that it is preferable to increase the determination value as the flow rate at the time of interruption increases.

Although the above determination method does not take into account the time from shutoff to unblocking, the longer the time it takes to restore, the more the pressure in the pipe will drop. It is also useful to make a correction to increase the judgment value as much as possible.

As described above, according to the present invention, the presence or absence of leakage can be determined at an early stage by obtaining the rate of change in the flow rate after the disconnection is canceled and comparing it with the determination value set by the determination value setting means 10 in consideration of the piping situation. .

It should be noted that the determination value setting in the determination value setting means 10 was described as setting the maximum flow rate immediately after disconnection, the flow rate change rate, the flow rate at the time of disconnection, etc., but the maximum flow rate immediately after disconnection, the flow rate change It is also possible to set the rate, the flow rate at the time of interruption, etc. in combination.

As described above, the gas shut-off device according to the present invention uses a membrane type sensor, an ultrasonic sensor, a hot wire sensor, a fluidic sensor, etc. to detect gases such as various gas mediums, LP gas, city gas, and hydrogen gas flowing in a pipe. It can be applied to applications such as water meters for measuring liquids such as water using ultrasonic sensors and the like.

REFERENCE SIGNS LIST 1 flow path 2 flow rate measuring means 3 shutoff means 4 abnormality determination means 5 recovery means 6 flow rate change rate calculation means 7 leakage determination means 8 notification means 9 determination value 10 determination value setting means

Claims (6)

a channel through which the fluid to be measured flows;
a flow rate measuring means for measuring the flow rate of the fluid to be measured flowing through the channel;
a blocking means for blocking the flow path;
Abnormality determination means for blocking the flow path with the blocking means when the flow rate obtained by the flow rate measuring means is determined to be abnormal;
a return means for canceling the blocking by the blocking means;
Flow rate change rate calculation means for obtaining a flow rate change rate from the flow rate measured by the flow rate measurement means after the shutoff is canceled by the return means;
After the flow rate change rate calculated by the flow rate change rate calculation means is determined to be equal to or less than a predetermined judgment value, if the flow rate measured by the flow rate measurement means is equal to or greater than a predetermined flow rate, it is determined that there is a leak, and the cutoff means determines the a leakage determination means for blocking the flow path;
A judgment value setting means for setting the judgment value,
The judgment value setting means sets the judgment value based on the flow rate measured by the flow rate measuring means and/or the flow rate change rate calculated by the flow rate change rate calculation means after the interruption is released. The gas cutoff device, wherein the leakage judgment means judges that the flow rate change calculated by the flow rate change rate calculation means is equal to or less than a predetermined judgment value. 2. The gas cutoff device according to claim 1 , wherein said judgment value setting means sets said judgment value according to the maximum flow rate in a predetermined time after said shutoff is canceled by said return means. 2. The gas shutoff device according to claim 1 , wherein said determination value setting means sets said determination value in accordance with a rate of change in flow rate in a predetermined time after said shutoff is released by said return means. 2. The gas shutoff device according to claim 1 , wherein said determination value setting means sets said determination value according to a rate of change in flow rate for a predetermined time after said shutoff is released by said reset means. 2. The gas cutoff device according to claim 1 , wherein said judgment value setting means sets said judgment value according to a flow rate when said abnormality judgment means judges an abnormality and said interruption means shuts off the gas. Having a timer that measures the time after the shutdown is canceled by the return means,
When the flow rate change rate calculated by the flow rate change rate calculating means does not become equal to or less than the decision value before the predetermined time is measured by the timing means, the leakage determination means determines that there is an abnormality, and causes the cutoff means to The gas shutoff device according to any one of claims 1 to 5 , which shuts off a passage.

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