JP2018205220A - Gas shutoff device - Google Patents

Abstract

To provide a shutoff device with which it is possible to optimize a restoration safety confirmation time.SOLUTION: A gas shutoff device of the present invention comprises: flow rate measurement means 2 for measuring a flow path 1 and a flow rate; shutoff means 3 for blocking the flow path 1; abnormality determination means 4 for blocking the flow path with the shutoff means 3 when it is determined that the flow rate obtained by the flow rate measurement means 2 is abnormal; restoration means 5 for removing blocking by the shutoff means 3; flow rage change rate computation means 6 for finding a flow change rate from the flow rates measured by the flow rate measurement means 2 after blocking is removed by the restoration means 5; and leakage determination means 7 for determining that there is leakage and blocking the flow path 1 with the shutoff means 3 when the flow rate measured by the flow rate measurement means 2 is greater than or equal to a prescribed flow rate after it is determined that the flow change rate computed by the flow change rate computation means 6 is smaller than or equal to a prescribed determination value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a gas shut-off device that measures a gas flow rate and monitors whether or not the usage state is safe.

  Conventionally, as this type of gas shut-off device, the gas flow rate is measured, and when the measured gas flow rate deviates from the normal use state, the gas is shut off by a built-in shut-off valve, and then the return, that is, the shut-off is released. A leakage confirmation method is disclosed (for example, see Patent Document 1).

  When the gas hose is shut off at an abnormally large flow rate due to disconnection of the gas hose (total flow rate cutoff), or when a gas appliance such as a stove is shut off for a long time exceeding the normal usage time (usage time cutoff), Since the raw gas in the piping naturally escapes until the disconnection factor is improved by correcting the disconnection or closing the cock of the gas appliance, the upstream side of the isolation valve is A large flow rate flows until the gas pressure in the downstream pipe, which has decreased due to a pressure difference from the downstream side, reaches the supply pressure. Thereafter, when the pressure becomes uniform, the measured flow velocity becomes zero or a value close to zero.

  However, if the shut-off valve is opened without any improvement of the shut-off factor for some reason, and the shut-off valve is opened, the flow rate will be once near zero after a large flow, but the plug of the gas appliance downstream of the pipe will open. Therefore, when the gas is filled, the flow rate gradually starts to increase, and a phenomenon of returning to the flow rate in the gas supply state immediately before the shut-off occurs.

  The leak check method described in Patent Document 1 uses this phenomenon to perform leak determination. After detecting and shutting off an abnormality, the shutoff is released by the return means and the plug is opened. When the flow rate at this time is a predetermined flow rate or more, it is determined that there is a leak.

JP 2006-118762 A

  However, in the conventional configuration, since the predetermined time for detecting the flow rate after the return is fixed at the time when the gas shut-off device at each customer's house is learned at the time of installation, the piping state due to equipment changes at each customer's house and environmental factors This is a problem in which the predetermined time is excessive with respect to the piping state of each customer's house and the return operation takes extra time, or the predetermined time is insufficient for the piping state of each customer's house and the pipe is being piped. There is a problem that the flow rate generated when the gas is filled is erroneously determined to be leakage, and a cutoff output is generated.

  The present invention solves the above-mentioned conventional problems, and when a gas shut-off device detects an abnormality and shuts off the gas, the gas leaks whether there is no use of the gas when the shut-off is released by opening the shut-off operation. An object of the present invention is to provide a gas shut-off device that makes a quick determination and monitors whether or not the use state of a gas appliance is safe.

In order to solve the above-described conventional problems, a gas shutoff device according to the present invention includes a flow path through which a fluid to be measured flows, a flow rate measurement unit that measures a flow rate of the fluid to be measured through the flow path, and the flow path. A shut-off means that shuts off the flow path when the flow rate determined by the flow-rate measuring means is abnormal, a return means that releases the shut-off by the shut-off means, and a return means After the interruption is released, the flow rate change rate calculating means for obtaining the flow rate change rate from the flow rate measured by the flow rate measuring means, and the flow rate change rate calculated by the flow rate change detecting means are determined to be equal to or less than a predetermined determination value. After that, when the flow rate measured by the flow rate measuring unit is equal to or higher than a predetermined flow rate, the flow rate measuring unit is configured to include a leakage determining unit that determines leakage and blocks the flow path by the blocking unit.

  As a result, a problem that requires extra time for the return operation, a problem that the judgment value is insufficient with respect to the piping state of each customer's house, and the flow rate generated when the gas fills the piping is erroneously determined as leakage and shut off It is possible to make a leak judgment suitable for the piping condition due to equipment changes at each customer's house and environmental factors, and the time required for the leak judgment can be optimized according to the pipe, so it takes more time than necessary. It is possible to make a judgment and improve usability.

  According to the gas shut-off device of the present invention, the time from the return means to the leakage determination is excessive or insufficient, and the problem that requires extra time for the return operation, the determination value is insufficient for the piping state of each customer's house. The flow rate generated when the gas fills the piping is not determined to be leaked and shut off, and it is possible to make a leak determination suitable for the piping status due to equipment changes at each customer's house and environmental factors. Since the time required for leak determination can be optimized according to the piping, it can be determined without requiring more time than necessary, and usability can be improved.

FIG. 1 is a control block diagram of the gas cutoff device according to Embodiment 1 of the present invention. Diagram for explaining the principle of flow measurement in the flow measurement means The graph for demonstrating the leak determination in Embodiment 1 of this invention Flowchart for explaining leakage determination in Embodiment 1 of the present invention Control block diagram of gas cutoff device of embodiment 2 of the present invention The graph for demonstrating the judgment value determination method in Embodiment 2 of this invention Graph for explaining a determination value determination method according to another example of Embodiment 2 of the present invention Graph for explaining a determination value determination method according to another example of Embodiment 2 of the present invention

  1st invention calculated | required with the flow path through which the to-be-measured fluid flows, the flow measurement means to measure the flow volume of the to-be-measured fluid which flows through the said flow path, the interruption | blocking means to interrupt | block the said flow path, and the said flow measurement means When the flow rate is determined to be abnormal, the abnormality determining means for blocking the flow path by the blocking means, the returning means for releasing the blocking by the blocking means, and the flow measuring means after the blocking is released by the returning means The flow rate change rate calculating means for obtaining the flow rate change rate from the measured flow rate, and the flow rate change rate calculated by the flow rate change rate calculating means is determined to be equal to or less than a predetermined determination value, and then measured by the flow rate measuring means. When the flow rate is equal to or higher than a predetermined flow rate, it is determined that there is a leakage and the leakage determination unit that blocks the flow path by the blocking unit, so that the time from the return unit to the leakage determination is excessive or insufficient. For return operation There is no problem that requires a long time, the judgment value is insufficient for the piping state of each customer's house, and the problem that the flow rate generated when the gas fills the pipe is erroneously determined as leakage and shut off, Leakage detection suitable for piping changes due to equipment changes and environmental factors at each customer's house can be performed, and furthermore, the time required for leakage detection can be optimized according to the piping, so it can be judged without taking more time than necessary, improving usability can do.

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

  The third invention is characterized in that, in particular, in the second invention, the judgment value setting means sets the judgment value according to the maximum flow rate immediately after the shutoff is released by the return means. .

  The fourth invention is characterized in that, in particular, in the second invention, the determination value setting means sets the determination value according to a flow rate change rate immediately after the shutoff is released by the return means. is there.

  A fifth invention is characterized in that, in particular, in the second invention, the judgment value setting means sets the judgment value according to a flow rate change rate for a predetermined time after the interruption is released by the return means. To do.

  A sixth invention is characterized in that, in particular, in the second invention, the determination value setting means sets the determination value according to a flow rate when the abnormality determination means makes an abnormality determination and is blocked by a blocking means. To do.

  In a seventh aspect of the invention, in particular, in the first to sixth aspects of the invention, there is provided a time measuring means for measuring time after the shut-off is released by the return means, and the leakage determining means measures a predetermined time by the time measuring means. If the flow rate change rate calculated by the flow rate change rate calculating means is not less than or equal to the determination value before the determination, it is determined that there is an abnormality and the flow path is blocked by the blocking means.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows a control block diagram of a gas shut-off device according to an embodiment of the present invention. A flow path 1 through which a gas as a fluid to be measured flows, a flow rate measuring means 2 for measuring a flow rate of gas flowing through the flow path 1, Blocking means 3 that shuts off the flow path 1, abnormality determination means 4 that shuts off the flow path at the blocking means 3 when the flow rate obtained by the flow rate measuring means 2 is determined to be abnormal, and return for releasing the blocking by the blocking means 3 The flow rate change rate calculating means 6 for obtaining the rate of change of the flow rate measured by the flow rate measuring means 2 and the rate of change obtained by the flow rate change rate calculating means 6 after the interruption is released by the means 5 and the return means 5 are predetermined determinations. After it is determined that the value is within 9, the leakage determining means 7 is configured to determine that leakage occurs when the flow rate measured by the flow rate measuring means 2 is a predetermined flow rate, and the blocking means 3 blocks the flow path 1.

  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 flow 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 fluid flow and the direction of ultrasonic propagation until the ultrasonic waves are reflected by the lower surface 1a. Also, let L be the effective length of the propagation path of the ultrasonic wave that propagates between the first ultrasonic transceiver 2a and the second ultrasonic transceiver 2b.

The control circuit 2c controls transmission of ultrasonic waves from the first ultrasonic transceiver 2a and reception of ultrasonic waves by the second ultrasonic transceiver 2b. The propagation time t1 until the ultrasonic wave transmitted from the first ultrasonic transmitter / receiver 2a reaches the second ultrasonic transmitter / receiver 2b is expressed by the following equation.

t1 = L / (C + Vcos 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 until the ultrasonic wave transmitted from the second ultrasonic transceiver 2b reaches the first ultrasonic transceiver 2a is expressed by the following equation.

t2 = L / (C−Vcos θ) (2)
When the sound velocity C of the fluid is eliminated from the equations (1) and (2), the following equation is obtained.

V = (L / (2 cos [theta])) * ((1 / t1)-(1 / t2)) (3)
As understood from the equation (3), if L and θ are known, the control circuit 2c measures the propagation times t1 and t2, and the flow velocity V is obtained. The arithmetic circuit 2d calculates the flow velocity V.

  Furthermore, the arithmetic circuit 2d calculates the flow rate Q by multiplying the flow velocity V by the cross-sectional area S and the coefficient k of the flow path 1 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 * V * S (4)
In the above-described example, the flow measurement principle of the so-called V-pass method has been described, but this is an example. A measurement principle called a so-called Z-pass method or I-pass method may be used.

  It is not essential that the flow rate measuring means 2 is an ultrasonic type. A known measuring instrument can be used as long as the flow rate of the fluid flowing through the partial flow path can be measured. The known measuring device may be, for example, a thermal flow sensor that measures a flow rate by using heat transfer caused by a flow. Since these are publicly known, the description thereof is omitted.

  With the above configuration, the flow rate measuring means 2 can measure the flow rate of the fluid flowing through the flow path 1, and performs measurement at a constant cycle, for example, every 2 seconds.

  The abnormality determination unit 4 determines whether or not the usage state is abnormal from the gas flow rate obtained by the flow rate measurement unit 2. For example, it is possible to detect an abnormally large flow rate that occurs when a hose that supplies gas to a gas appliance such as a stove is disconnected for some reason, or to monitor the usage time of the gas appliance, and to use it for maximum use. It detects whether the time has been exceeded and monitors for abnormal usage.

  And when abnormality is detected by the abnormality determination means 4, safety | security is ensured by interrupting | blocking the flow path 1 with the interruption | blocking means 3, and stopping gas.

  The return means 5 is for canceling the blocking of the flow path 1 detected by the abnormality determining means 4 and being blocked by the blocking means 3, and for issuing a return instruction so that the gas can be used again. Etc.

  The flow rate change rate calculation means 6 calculates the rate of change of the flow rate from the flow rate detected last time by the flow rate measurement means 2 and the flow rate detected this time after the shutoff is released by the return means 5.

The leakage determination means 7 compares the flow rate change rate with the determination value 9 by the flow rate change rate calculation means 6 and determines that the flow rate measured by the flow rate measurement means 2 is equal to or less than a predetermined flow rate after determining that it is within the determination value. If the flow rate is not 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 use state is abnormal or when the leakage determination means 7 determines that the gas is leaking. In addition, the telephone line is used to notify the center that is monitoring the safety of gas.

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

  FIG. 3 shows that the gas flow is shut off by detecting that the maximum judgment flow rate set larger than the flow rate assumed by the normal use of the gas appliance has been exceeded due to an abnormality such as the hose coming off while the gas appliance is being used. The graph shows the change in the gas flow rate when the shut-off is released by the return operation and the piping from which gas has escaped is filled with gas.The solid line indicates the response to the abnormality when the cause of the abnormality is eliminated after the shut-off. Indicates a case where leakage is insufficient.

  First, when any abnormality is detected in the flow rate measured by the flow rate measuring unit 2 (here, when the maximum determination flow rate is exceeded), the flow path 1 is first blocked by the blocking unit 3 (blocking A).

  Thereafter, the blocking factor is released. 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 so that the flow path 1 is opened.

  After shutting off, the gas in the piping naturally escapes until the cause of the abnormality is improved. Immediately after releasing the shutoff, there is a pressure difference between the upstream side (supply side) and the downstream side of the shutting means 3, and the pressure drops. The gas flows until the gas pressure in the downstream pipe reaches the pressure on the supply side. Thereafter, when the cause of the abnormality is improved, the flow rate of the gas detected by the flow rate measuring means 2 gradually decreases as shown by the solid line, and decreases to near zero when the pressure becomes uniform. The time to decrease 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 released, the leakage determination unit 7 determines whether the flow rate fluctuation is stable depending on whether the flow rate change rate detected by the flow rate change rate calculation unit 6 is equal to or less than the determination value. If it is determined that the flow rate change rate is equal to or less than the predetermined value and is stable, and if the flow rate measured by the flow rate measuring means 2 does not flow above the predetermined flow rate, the cause of the abnormality is eliminated and there is no leakage. Judge.

  On the other hand, when the leak is occurring without eliminating the cause of the abnormality, the flow rate of the gas asymptotic to the leak flow rate q is detected as indicated by the dotted line. When it is determined that the rate is equal to or less than the determination value, it is determined that leakage has occurred for some reason because the flow rate measured by the flow rate measuring unit 2 is greater than or equal to the predetermined flow rate. 1 is cut off (block B).

  In the case of a shutoff exceeding the maximum judgment flow rate due to a gas hose disconnection, etc., if a return operation is performed without improving the cause of the abnormality, an error occurs because the gas exceeding the maximum judgment flow rate flows simultaneously with the release of the shutoff. When the abnormality is detected by the determination means 4, the interruption is executed again (interruption C).

Next, the process of the leakage determination means 7 in this Embodiment is demonstrated using the flowchart of FIG. It is assumed that the blocking process by the blocking unit 3 is performed by another process when the abnormality determining unit 4 determines that an abnormality has occurred. Here, the process in the leakage determining unit 7 will be mainly described.

  First, the flow rate measuring means 2 measures the flow rate (S001), determines the presence or absence of a return operation F, which will be described later, and branches to the flow rate change rate calculation process (S008) if the return operation is in progress. For example, it is determined whether or not there is an interruption (S003), and if it is being interrupted, the presence or absence of the operation of the return switch is determined (S004). A return operation F for indicating the return operation is set (S005), a monitoring timer for monitoring the time of the return operation process is started (S006), and the blocking by the blocking means 3 is released (S007).

  Next, the flow rate change rate calculating means 6 calculates a flow rate change rate from the previous flow rate value and the current flow rate value measured by the flow rate measuring means 2 (S008), and whether the change rate is equal to or less than a predetermined determination value. (S009), if it is below, it is judged that the flow rate is stable, 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 if a flow rate exceeding the determined flow rate is measured, it is determined that leakage has occurred (S014), and the shutoff is performed again (S015). .

  In step S009, if the flow rate change rate is not less than a predetermined value, it is determined that the flow rate is not stable, and it is further determined whether the time counted by the monitoring timer has exceeded the monitoring time (S010). If it does not exceed, the process is skipped, and if it exceeds, it is determined that the flow rate is not stable, it is determined that an unforeseen abnormality has occurred, and the interruption is performed again (S015).

  Through the above processing, when no leakage is detected at normal times, it is determined that the blocking factor has been improved, and the flow path 1 can be opened to make the gas appliance usable.

  After detecting and shutting off abnormalities during use of gas appliances in this way, the return means 5 uses a slope (change rate) that determines whether there is no gas leakage after returning the shut-off means 3 depending on the piping. By doing so, it is possible to optimize the time required for leakage determination according to the piping, so that it can be determined without requiring more time than necessary, and usability can be improved.

(Embodiment 2)
FIG. 5 shows a control block diagram of the gas shut-off device according to the second embodiment of the present invention. The same reference numerals as those in the first embodiment have the same structure and the same functions, and the description thereof is omitted. The difference from the first embodiment is that a determination value setting means 10 for determining a determination value 9 to be compared with the flow rate change rate obtained by the flow rate change rate calculation means 6 is provided.

  In the first embodiment, the determination value of the flow rate change rate has been described as a predetermined value set in advance. However, in the second embodiment, the determination value setting means 10 is the maximum immediately after the shutoff is released by the return means 5. The determination value is determined according to the flow rate.

  FIG. 6 shows an example of the change in the maximum flow rate immediately after the release of the shutoff by the return operation and the change in the flow rate due to the presence or absence of leakage thereafter. As shown in the figure, the larger the maximum flow rate regardless of the presence or absence of leakage, Since it takes time to stabilize, if the determination value is the same, it is not preferable that the maximum flow rate immediately after the release of the shutoff is large, it takes time to stabilize. Therefore, the determination value setting means 10 sets the determination value to a larger value as the maximum flow rate immediately after the release of the shutoff is larger in order to perform the leakage determination at an early stage.

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

  Fig. 7 shows an example of the flow rate change due to the presence or absence of leakage when the maximum flow rate immediately after release of the cutoff is the same, but the rate of change in flow rate is different. If the rate of change in flow rate immediately after is small, it takes time until it becomes stable. Therefore, if the judgment 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 be a larger value as the flow rate change rate immediately after the release of the cutoff is smaller. In this case, it is also possible to determine the determination value not only based on the flow rate change rate immediately after release of the interruption, but also based on the magnitude of the gradient over a certain period of time.

  Moreover, this determination value can also be determined according to the magnitude of the flow rate at the time of interruption.

  FIG. 8 shows an example of the shutoff reason (difference in flow rate at shutoff) and the flow rate change after shutoff return. When the solid line up to shutoff exceeds the maximum judgment flow rate, the dotted line usually assumes a gas appliance. As shown in the figure, since the pressure drop increases as the flow rate at the time of shutoff increases, the maximum flow rate immediately after release of the shutoff also increases. Therefore, it is understood that it is preferable to increase the determination value as the flow rate at the time of interruption is larger.

  In the above determination method, the time from shut-off to release of shut-off is not taken into account, but the pressure of the piping decreases as the time from return to start increases. Therefore, the time T is long considering the time T to return. It is also useful to perform correction to increase the determination value.

  As described above, according to the present invention, the flow rate change rate after the release of the shut-off is obtained, and the presence or absence of leakage can be determined at an early stage by comparing with the determination value set in consideration of the piping condition by the determination value setting means 10. .

  Although the determination value setting in the determination value setting means 10 has been described as being set for each of the maximum flow rate immediately after release of the cutoff, the flow rate change rate, the flow rate at the time of cutoff, etc., the maximum flow rate immediately after release of the cutoff and the flow rate change are described. It is also possible to set the rate, the flow rate at the time of shut-off, etc. in combination.

  As described above, the gas shutoff device according to the present invention includes various gas media, LP gas, city gas, and hydrogen gas flowing in the pipe using a membrane type, ultrasonic sensor, hot wire sensor, fluidic sensor, and the like. It can be applied to uses such as water meters that measure liquids such as water using measurement or ultrasonic sensors.

DESCRIPTION OF SYMBOLS 1 Flow path 2 Flow measurement means 3 Blocking means 4 Abnormality determination means 5 Restoration means 6 Flow rate change rate calculation means 7 Leakage determination means 8 Notification means 9 Determination value 10 Determination value setting means

Claims (7)

A flow path through which the fluid to be measured flows;
Flow rate measuring means for measuring the flow rate of the fluid to be measured flowing through the flow path;
Blocking means for blocking the flow path;
An abnormality determining means for blocking the flow path by the blocking means when it is determined that the flow rate obtained by the flow rate measuring means is abnormal;
Returning means for releasing the blocking by the blocking means;
A flow rate change rate calculating means for obtaining a flow rate change rate from the flow rate measured by the flow rate measuring means after the shutoff is released by the return means;
After the flow rate change rate calculated by the flow rate change rate calculating means is determined to be less than or equal to a predetermined determination value, if the flow rate measured by the flow rate measuring means is greater than or equal to a predetermined flow rate, it is determined that there is a leak and the blocking means Leakage determination means for blocking the flow path;
Gas shut-off device with A determination value setting means for setting the determination value;
The determination value setting unit sets the determination value based on a flow rate measured by the flow rate measurement unit and / or a flow rate change rate calculated by the flow rate change rate calculation unit. Gas shut-off device. The gas cutoff device according to claim 2, wherein the judgment value setting means sets the judgment value according to a maximum flow rate immediately after the shutoff is released by the return means. The gas cutoff device according to claim 2, wherein the judgment value setting means sets the judgment value according to a flow rate change rate immediately after the shutoff is released by the return means. The gas cutoff device according to claim 2, wherein the judgment value setting means sets the judgment value according to a flow rate change rate for a predetermined time after the shut-off is released by the return means. The gas cutoff device according to claim 2, wherein the judgment value setting means sets the judgment value in accordance with a flow rate when the abnormality judgment means makes an abnormality judgment and is shut off by a shut-off means. After the shut-off is released by the return means, it has time measuring means for measuring time,
When the flow rate change rate calculated by the flow rate change rate calculation unit does not become less than or equal to the determination value before the predetermined time is measured by the time measuring unit, the leakage determination unit determines that the abnormality is present and the blocking unit determines the flow rate. The gas cutoff device according to any one of claims 1 to 6, wherein the passage is shut off.

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