JP3255520B2 - Gas shut-off device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas shut-off device for detecting a gas leak or an abnormal use state of a gas and shutting off the gas.

[0002]

2. Description of the Related Art In recent years, a household gas meter has a function of measuring the flow rate of gas passing through a flow meter, and detects a gas supply pressure with a pressure switch, and detects a pressure drop when the gas is not used. When the gas flow is detected, or when the gas flow rate is detected by the flow meter at a predetermined amount or more, or when the gas flow rate is detected for a predetermined period or more, the gas safety valve is operated to close the gas flow path by driving the gas shutoff valve. Some have a blocking function. As a result, gas leaks in the pipes and unnatural gas leaks are detected to prevent accidents,
It guarantees safety.

[0003] Incidentally, the gas safety shut-off function includes, for example, as shown in Japanese Patent Application Laid-Open No. 3-217716, the number of gas appliances currently used from the measured current gas flow and past gas flow. In some cases, the individual flow rate of each gas appliance is estimated, and the gas cutoff time is set according to the maximum individual flow rate. This is based on the consideration that the gas appliance having a large flow rate such as a gas water heater has a short use time, and the gas appliance having a small flow rate such as a stove has a long use time.

[0004]

However, in the conventional gas safety shut-off function of shutting off the gas when the gas flow rate is detected for a predetermined period or more, the increase / decrease of the number of gas appliances is determined based only on the fluctuation amount of the gas flow rate. Therefore, there is a problem as described below, and there is a problem that it takes time to grasp an abnormal use state of the gas appliance. (1) When a plurality of gas appliances start to be used simultaneously, 1
They mistakenly recognize that two gas appliances have begun to be used. (2) When the total gas flow rate decreases, it cannot be specified whether the use of one gas appliance or the use of a plurality of gas appliances has ended. (3) Even if one gas appliance is used, if the overall flow rate changes due to automatic flow control or manual operation of the gas appliance itself,
The user mistakenly recognizes that a new gas appliance has started to be used or that the gas appliance has been used.

[0005] Further, even when the same gas flow rate continues for a long time, it is necessary to shut off the gas in a short time in the case of a gas leak. For example, a gas appliance equipped with a gas governor such as a fan heater is used. In such a case, it is not appropriate to shut off the gas in a short time because there is no risk of gas leakage. Therefore, if the gas shut-off time is set based only on the individual flow rate as in the related art, there is a possibility that a trouble may occur in which the gas is shut off when there is no danger, or the gas is not shut off when it is dangerous.

The present invention has been made in view of such a problem, and an object thereof is to realize a more sophisticated gas safety shut-off function by setting a gas shut-off time according to the type of gas appliance to be used. An object of the present invention is to provide a gas shut-off device as described above.

[0007]

According to a first aspect of the present invention, there is provided a gas shut-off device, comprising: storage means for storing information indicating a relationship between a gas flow rate set for each type of gas appliance and a safety continuation time; A gas flow rate detecting means for detecting a gas flow rate passing through the gas supply path; and when a change occurs in the gas flow rate detected by the gas flow rate detecting means, a change flow rate is calculated, and an individual gas is calculated based on the change flow rate. Individual gas appliance flow rate calculating means for determining the flow rate of each appliance, gas appliance discriminating means for discriminating the type of gas appliance being used, and discrimination by the gas appliance discriminating means using information stored in the storage means. The safety duration is determined based on the type of gas appliance and the flow rate of each individual gas appliance obtained by the individual gas appliance flow rate calculation means, and this safety duration is set as the cutoff time A cutoff time setting means that, when the elapsed breaking time set by the cutoff time setting means from the start of use of the gas appliance, and a gas shut-off means for stopping the supply of gas to the gas appliance, the gas appliance determination unit ,
A gas supply pressure for a gas appliance provided in the gas supply path
Gas pressure detection means for detecting force and active gas supply pressure
Pressure fluctuation means for dynamically changing the pressure,
Before and after pressure fluctuations
Pressure detection means when the gas flow rate
Therefore, the detected gas supply pressure and gas flow rate detection means
Used based on the detected gas flow rate
As the type of gas appliance, the gas of the gas appliance used
Determining means for determining the presence or absence of governor equipment .

[0008] In this gas shut-off device, the storage means stores information representing the relationship between the gas flow rate set for each type of gas appliance and the safety continuation time. Further, when a change occurs in the gas flow rate detected by the gas flow rate detecting means, the changing flow rate is calculated by the individual gas appliance flow rate calculating means, and the flow rate of each individual gas appliance is obtained based on the changed flow rate. Further, the type of the gas appliance used is determined by the gas appliance determination unit. Then, using the information stored in the storage means, by the cutoff time setting means, the type of the gas appliance determined by the gas appliance determination means and the flow rate of the individual gas appliance unit determined by the individual gas appliance flow rate calculation means. The safety duration is determined based on the safety duration, and the safety duration is set as the cutoff time. Then, when the cutoff time set by the cutoff time setting means has elapsed from the start of use of the gas appliance, the supply of gas to the gas appliance is stopped by the gas cutoff means. In particular, in this gas shutoff device, the pressure fluctuation means
Actively changes the gas supply pressure,
Gas in the gas supply path before and after the fluctuation
When the gas flow rate is stable,
Detected by the detected gas supply pressure and gas flow rate detection means
Based on the gas flow rate output, the
The type of gas appliance used
The presence / absence of gas governor equipment is determined.

[0009]

[0010]

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 13 relate to one embodiment of the present invention.

FIG. 1 is an explanatory diagram showing a schematic configuration of a gas meter including a gas shut-off device of the present embodiment. A gas pipe 11 for supplying gas a to a plurality of gas appliances is provided inside the gas meter 10. The gas pipe 11 has an on-off valve 12 such as a valve for changing the pressure of gas supplied to the downstream side of the gas meter 10 by changing the flow rate of gas passing therethrough, and for shutting off a gas flow path in an abnormal condition. , A gas pressure sensor 14 for detecting the pressure of the gas in the gas flow path, and a gas flow meter 15 for detecting the flow rate of the gas passing through the gas flow path.

The gas meter 10 is provided with a control unit 16 for inputting respective outputs of the gas pressure sensor 14 and the gas flow meter 15 and for controlling the on-off valve 12 and the gas cutoff valve 13.

FIG. 2 is a block diagram showing the configuration of the control unit 16 and its surroundings constituting the gas shut-off device of the present embodiment.
As shown in this figure, the control unit 16 includes a CPU (central processing unit) 30, a ROM (read only memory) 31,
It has a RAM (random access memory) 32, a clock 33 and an input / output port 34, which are connected to each other by a bus 35. The input / output port 34 is connected to the gas pressure sensor 14, the gas flow meter 15, a drive circuit 36 for driving the gas cutoff valve 13, and a drive circuit 37 for driving the on-off valve 12. This control unit 16
In this configuration, the CPU 30 executes a program stored in the ROM 31 using the RAM 32 as a working area to realize a function as a gas shutoff device.

FIG. 3 is a functional block diagram showing functions of the gas shut-off device of the present embodiment. As shown in this figure, the gas shut-off device is provided with a pressure detecting means 41 for detecting a gas supply pressure.
And a flow rate detecting means 42 for detecting a gas flow rate, and a storage means 43 for storing the detected values of the pressure detecting means 41 and the flow rate detecting means 42. Pressure detecting means 41
Is realized by the gas pressure sensor 14, the flow rate detecting means 42 is realized by the gas flow meter 15, and the storage means 43
Is realized by the RAM 32.

The gas shut-off device further includes a flow rate detecting means 42.
Flow rate calculating means 44 for calculating a flow rate when a change occurs in the gas flow rate detected by the above, and obtaining a flow rate (hereinafter, referred to as an individual flow rate) for each individual gas appliance based on the change flow rate; Active pressure fluctuation means 45 for actively fluctuating the supply pressure, and active pressure fluctuation means 4
5 before and after the pressure fluctuation by
1, when the gas flow rate is stable, the gas supply pressure is detected by the pressure detection means 41 and the gas flow rate is detected by the flow rate detection means 42, and based on the detected gas supply pressure and the gas flow rate, the total And a flow ratio calculating means 46 for calculating a ratio of a gas flow rate supplied to a gas appliance equipped with a gas governor to the gas flow rate. The individual flow rate calculating means 44 and the flow rate calculating means 46
Reads out from the storage means 43 the values of the gas flow rate and gas supply pressure necessary for the calculation. The individual flow rate calculating means 44 and the flow rate calculating means 46 are realized by the control unit 16, and the active pressure changing means 45 is realized by the control unit 16, the drive circuit 37 and the on-off valve 12.

The gas cutoff device further comprises a flow ratio calculating means 4
6 and the total gas flow detected by the flow detecting means 42, the gas flow supplied to the gas appliance equipped with the gas governor and the gas supplied to the gas appliance not equipped with the gas governor are supplied. Flow rate calculating means 4 for determining the gas flow rate and for determining whether the gas governor is provided or not
7 is compared with the individual flow rate calculated by the individual flow rate calculation means 44 and the gas flow rate calculated by the flow rate calculation means 47 without gas governor equipment to determine whether the gas appliance used is equipped with a gas governor. And a discriminating means 48 for discriminating the type of gas appliance used based on the discrimination result of the presence or absence of the gas governor equipment and the individual flow rate calculated by the individual flow rate calculating means 47. The flow rate calculating means 47 with or without gas governor is configured to read the value of the total gas flow rate required for the calculation from the storage means 43. The flow rate calculating means 47 and the discriminating means 48 according to whether or not the gas governor is provided are realized by the control unit 16.

The gas shutoff device further includes a first safety continuation time table 51 and a second safety continuation time table 52 as information indicating the relationship between the gas flow rate set for each type of gas appliance and the safety continuation time. Storage means 50 for storing
Using the information stored in the storage means 50, a safety continuation time is determined based on the type of gas appliance determined by the determination means 48 and the individual flow rate obtained by the individual flow rate calculation means 44, and the safety continuation time is determined. A cut-off time setting means 53 for setting a time as a cut-off time, and a gas cut-off means 54 for stopping supply of gas to the gas appliance when the cut-off time set by the cut-off time setting unit 53 has elapsed from the start of use of the gas appliance. And The storage means 50 is realized by the ROM 31 or the non-volatile RAM 32. The cutoff time setting means 53 is realized by the control unit 16. Further, the gas shut-off means 54 includes the control unit 16,
This is realized by the drive circuit 36 and the gas shutoff valve 13.

Next, the operation of the gas shut-off device of this embodiment will be described.

FIG. 4 is a flowchart showing the entire operation of the gas shut-off device. As shown in this figure, the gas shutoff device first determines whether or not use of a new gas appliance has been started based on the gas flow rate detected by the flow rate detection means 42 (step S101). That is, when a change occurs in the gas flow rate detected by the flow rate detection means 42, the change flow rate is calculated, and when the change flow rate exceeds a predetermined positive value, the use of a new gas appliance is started. Judge that it was done.

When it is determined that the use of a new gas appliance has been started (step S101; Y), the individual flow rate X is calculated from the changed flow rate and registered (step S10).
2). Also, when the use of new gas appliances is started,
The active pressure varying means 45 drives the on-off valve 12 to actively vary the gas supply pressure. Flow ratio calculating means 46
When the gas flow rate is stable before and after the pressure fluctuation, the gas supply pressure is detected by the pressure detection means 41 and the gas flow rate is detected by the flow rate detection means 42. Based on the flow rate, the ratio (flow rate) of the gas flow rate supplied to the gas appliance equipped with the gas governor to the total gas flow rate is calculated (step S103). Next, based on the flow ratio calculated by the flow ratio calculating means 46 and the total flow rate detected by the flow rate detecting means 42, the flow rate calculating means 47 for each gas governor-equipped or non-equipment-equipped gas tool having a gas governor out of the total flow rate. The sum Y of the flowing flow rates and the sum Z of the flow rates flowing to the gas appliances having no gas governor out of the total flow rates are calculated (step S104). Next, the discriminating means 48 calculates the individual flow rate X at the time of registration obtained by the individual flow rate calculating means 44 and the gas flow rate Y obtained by the flow rate calculating means 47 without gas governor equipment.
Z, the presence or absence of gas governor equipment of the gas appliance being used is determined. Based on the determination result of the presence or absence of the gas governor equipment and the individual flow rate X obtained by the individual flow rate calculation means 44, the used gas appliance is used. The type of gas appliance that is present is determined (step S105).

Next, the cutoff time setting means 53 determines whether or not the newly registered individual flow rate is the largest of the registered individual flow rates (step S106).
If it is the maximum (Y), the cutoff time setting means 5
3 sets a cutoff time (step S107), and proceeds to step S108. If not the largest (N),
The cutoff time setting means 53 proceeds to step S108 without setting the cutoff time. In step S108, the gas shut-off unit 54 refers to the time measured by the clock 33 and starts using the gas appliance for which the shut-off time is set.
It is determined whether or not the cutoff time set by the cutoff time setting means 53 has elapsed (step S108). If the shutoff time has elapsed (Y), the gas shutoff means 54 drives the gas shutoff valve 13 to shut off the supply of gas to the gas appliance (step S109), and ends the operation. When the cutoff time has not elapsed (Step S108; N)
Returns to step S101.

On the other hand, when it is not determined in step S101 that the use of a new gas appliance has been started (N).
In step S110, the gas shutoff device determines whether the use of the gas appliance has been completed based on the gas flow rate detected by the flow rate detection unit 42. That is, when a change occurs in the gas flow rate detected by the flow rate detection means 42, the change flow rate is calculated, and when the change flow rate exceeds a predetermined negative value, the use of the gas appliance is terminated. to decide. When it is not determined that the use of the gas appliance has been completed (Step S110; N), the process proceeds to Step S108.

When it is determined that the use of the gas appliance has been completed (step S110; Y), the individual flow rate is calculated from the changed flow rate, and the registration of the individual flow rate is deleted (step S111). Next, the cutoff time setting unit 53 determines whether or not the registered individual flow rate is the largest of the registered individual flow rates (step S112).
If it is the maximum (Y), the cut-off time setting means 53 sets a cut-off time (step S107), and proceeds to step S108. If not the largest (N)
Then, the cut-off time setting means 53 proceeds to step S108 without setting the cut-off time.

FIG. 5 is a flow chart showing the operation of "flow rate ratio calculation" (step S103) in FIG. In this "flow rate ratio calculation", first, the flow ratio calculation means 46 waits for the gas flow rate detected by the flow rate detection means 42 to stabilize (step S121). Using the detection means 42, the gas supply pressure H ₁ and the gas flow rate Q ₁ before the active pressure fluctuation are detected (step S122), and stored in the storage means 43.

Next, the active pressure varying means 45 varies the gas supply pressure in a stepwise manner (step S123).
Next, the flow ratio calculating means 46 waits for the gas flow rate detected by the flow detecting means 42 to stabilize (Step S).
124) When the gas flow rate is stabilized, the gas supply pressure H ₂ after the active pressure fluctuation and the gas flow rate Q ₂ are detected using the pressure detection means 41 and the flow rate detection means 42 (step S125), and the storage means 43 To memorize.

Next, the flow ratio calculating means 46 stores the storage means 4
Based on the gas supply pressures H ₁ , H ₂ before and after the active pressure fluctuation stored in 3 and the gas flow rates Q ₁ , Q ₂ ,
The ratio (flow ratio) of the gas flow rate supplied to the gas appliance equipped with the gas governor to the total gas flow rate is determined (step S126), and the operation is terminated. In order to increase the accuracy of the gas supply pressure and the gas flow rate, an average value for a predetermined time may be obtained.

The flow rate ratio is specifically determined by the following equation.

[0029]

[Equation 1] {Q ₂ √H ₁ -Q ₁ √H ₂ ｝ / ｛Q ₁ (√H ₁ -√H ₂ )}

Here, the meaning of the above equation will be described. Generally, in a gas meter, when the gas supply pressure is actively changed, for example, when a gas governor (pressure regulator) is provided in a gas appliance to be used, such as a gas grill, the gas supply pressure is changed. Is absorbed by the gas governor, so that the gas flow rate has no effect. On the other hand, when there is nothing obstructing the flow of gas inside the used gas appliance, that is, when a gas governor such as a gas table is not provided, there is a theoretical relationship between the square root of the gas supply pressure and the gas flow rate. There is a proportional relationship.

Therefore, when a plurality of gas appliances are used, the gas flow rate Q ₁ before active pressure fluctuation is expressed by the following equation.

[0032]

[Equation 2] Q ₁ = A′√H ₁ + B ₁ = A√H ₁

Where A 'and A are constants, and A = A'
+ (B ₁ / √H ₁ ). Further, B ₁ is a flow through the gas appliance gas governor is fitted.

The gas flow rate Q ₂ after the active pressure change is expressed by the following equation.

[0035]

[Equation 3] Q ₂ = A′√H ₂ + B ₁

Here, the difference between Q ₂ and A√H ₂ is given by the following equation.

[0037]

Equation 4] _{Q 2 -A√H 2 = B 1 {} 1-√ (H 2 / H 1)}

If the left side is zero, all of the gas appliances do not have a gas governor; otherwise, the gas flow rate B ₁ flowing through the gas appliance having a gas governor is as follows.

[0039]

B ₁ = {Q ₂ −Q ₁ } (H ₂ / H ₁ )} / {1 − {(H ₂ / H ₁ )}

When this is divided by the total flow rate Q ₁ , the ratio (flow rate ratio) of the flow rate flowing through the gas appliance having the gas governor to the total flow rate is obtained as follows.

[0041]

B ₁ / Q ₁ = {Q ₂ √H ₁ -Q ₁ √H ₂ ｝ / ｛Q ₁ (√H ₁ -√H ₂ )｝

FIG. 6 shows "Gas appliance discrimination" in FIG.
It is a flowchart which shows operation | movement of (step S105). In this “gas appliance discrimination”, first, the discriminating unit 48 sends the individual flow rate X at the time of registration and the gas appliance having the gas governor out of the total flow rate from the individual flow rate calculating unit 44 and the flow rate calculating unit 47 without gas governor equipment. The sum Y of the flowing flow rates and the sum Z of the flow rates flowing to the gas appliances having no gas governor out of the total flow rates are acquired (step S131).

Next, the determination means 48 determines whether X is greater than Z (step S132). If X is larger than Z (Y), it is determined that the appliance has a gas governor (step S133). If X is not larger than Z (step S132; N), it is determined whether X is larger than Y (step S134). If X is larger than Y (Y), it is determined that the appliance does not have a gas governor (step S135). If X is not larger than Y (Step S134; N), the presence or absence of the gas governor is not determined (Step S136).

Next, the discriminating means 48 discriminates the type of the gas appliance to be used on the basis of the judgment result of the presence or absence of the gas governor and the individual flow rate X (step S137), and ends the operation.

Step S13 of the above-mentioned "discrimination of gas appliances"
The method of determining the presence or absence of the gas governor in 2 to S135 is based on the following considerations. That is, consider a case where three gas appliances have begun to be used sequentially. Also, let X be the individual flow rate of the gas appliance started to be used for the third time. If this individual flow rate X is larger than the total flow rate Z of the flow rate flowing through the gas appliance having no gas governor in the total flow rate, the third gas appliance which has started to use will obviously be a gas appliance having a gas governor. Presumed. Conversely, if the individual flow rate X is larger than the sum Y of the flow rates flowing through the gas appliance having the gas governor out of the total flow rate, the third gas appliance that has started to use is obviously a gas appliance without a gas governor. It is estimated that there will be.

As a method of determining whether or not the gas governor is provided, a method using fuzzy inference as described below may be used.

In this fuzzy inference, first, the following two rules are adopted. (Rule 1): If the individual flow rate X is larger than the sum Y of the flow rates flowing through the gas appliance equipped with the gas governor out of the total flow rate and the individual flow rate X is very small,
The gas appliance without gas governor is very high (the gas appliance with gas governor is very low). (Rule 2): If the individual flow rate X is larger than the sum Z of the flow rates flowing through the gas appliances not equipped with the gas governor out of the total flow rate, and if the individual flow rate X is very large, the gas appliance equipped with the gas governor is used. Is very high.

Rule 1 clearly states that if the individual flow rate X is greater than the sum Y of the flow rates flowing through the gas appliances equipped with the gas governor out of the total flow rate, the gas appliance used is obviously equipped with the gas governor. It is based on two facts that it is highly likely that the gas appliance is not used and that the gas appliance that uses a small gas flow rate is often a gas appliance not equipped with a gas governor. Rule 2
Obviously, if the individual flow rate X is greater than the sum Z of the flow rates flowing through the gas appliances not equipped with a gas governor out of the total flow rate, obviously the gas appliance used may be equipped with a gas governor. Is high, and the gas appliances that use a large gas flow rate are often gas appliances equipped with a gas governor.

The above two rules can be expressed as follows. In addition, U is a value representing a gas appliance equipped with a gas governor, and a positive value indicates that a gas appliance equipped with a gas governor is larger than a gas appliance not equipped with a gas governor, and a negative value indicates a gas appliance equipped with a gas governor. It is assumed that the gas appliance without gas governor is larger than the gas appliance. Also, PB is "very large",
PS is “positive value and absolute value is very small”, and NB is “negative value and absolute value is very large”. (Rule 1): IF XY = PB AND A = PS
THEN U = NB (Rule 2): IF XZ = PB AND A = PB
THEN U = PB

FIG. 7 is a membership function of "XY", FIG. 8 is a membership function of "XZ", FIG. 9 is a membership function of "X", and FIG. 10 is a membership function of "U" It is. These membership functions are set, for example, in an appropriate shape by conducting an experiment in advance so that the discrimination result of the gas appliance equipped with the gas governor matches the actual presence / absence of the gas governor. Further, each membership function may be changed according to the actual situation.

In the method using the fuzzy inference, the individual flow rate X obtained by the individual flow rate calculation means 44 and the gas flow rate Y obtained by the flow rate calculation means 47 without the gas governor are used by using such rules and membership functions. Based on Z, it is inferred by fuzzy inference whether the gas appliance used is equipped with a gas governor. As the inference method, for example, a MIN (logical product) -MAX (logical sum) -centroid synthesis method is used.

FIG. 11 shows the "interruption time setting" in FIG.
It is a flowchart which shows operation | movement of (step S107). In this “interruption time setting”, first, the interruption time setting means 53
However, it is determined whether the appliance having the maximum individual flow rate is equipped with the gas governor using the determination result of the determination unit 48 (step S141). When the gas governor is provided (Y), the cutoff time setting means 53 uses the individual flow rate obtained by the individual flow rate calculation means 44 as a key input,
The safety duration is acquired using the first safety duration table 51 (step S142). On the other hand, when the gas governor is not provided (Step S141; N), the cutoff time setting means 53 uses the individual flow rate obtained by the individual flow rate calculation means 44 as a key input to display the second safety continuation time table 52. Then, a safety duration time is acquired using the information (step S143). And the cutoff time setting means 53
The safety duration obtained in step S142 or step S143 is set as the cutoff time (step S14).
4) End the operation. If the determination means 48 does not determine whether or not the gas governor is provided, it is determined in advance so that the safety continuation time is obtained using one of the safety continuation time tables. Alternatively, an average value of the safety continuation times obtained using the two safety continuation time tables may be set as the cutoff time, or a safety continuation time table used when the presence or absence of the gas governor is not determined is provided. You can leave it.

FIG. 12 shows the first safety duration table 51.
FIG. 13 is a characteristic diagram showing an example of the relationship between the flow rate and the safety shut-off time as the contents of the second safety continuation time table 52. FIG. . As shown in these figures, in each of the tables 51 and 52, the larger the flow rate, the shorter the safety shut-off time. This takes into account the fact that gas appliances with a high flow rate have a short usage time, gas appliances with a low flow rate have a long usage time, and that in the case of gas leakage, the higher the flow rate, the higher the risk. is there. Further, the first safety duration table 51 used in the case of the appliance equipped with the gas governor has the same flow rate as the second safety duration table 52 used in the case of the appliance not equipped with the gas governor. But the safety shut-off time is longer. This is because there is no danger of gas leakage in the case of a device equipped with a gas governor. In addition, since there is no gas appliance having a large flow rate and not equipped with a gas governor, when the second safety duration table 52 is used, the gas is immediately shut off at a large flow rate.

The gas shut-off means 54 drives the gas shut-off valve 13 when the set shut-off time has elapsed from the start of use of the gas appliance for which the shut-off time has been set as described above, and controls gas supply to the gas appliance. Shut off supply.

If the newly registered individual flow rate is the largest of the registered individual flow rates, the cutoff time is set (steps S106 and S107 in FIG. 4).
This is because, in this case, the newly set interruption time may be shorter than the already set interruption time.

If the registered individual flow rate is the largest of the registered individual flow rates, the cutoff time is reset (steps S112 and S107 in FIG. 4).
This is because the use of the gas appliance for which the shutoff time is set is terminated before the elapse of the shutoff time, so that it is not necessary to shut off the gas at the already set shutoff time. In this case, the cutoff time is reset according to the maximum flow rate among the registered individual flow rates.

As described above, according to the present embodiment, the presence or absence of the gas governor of the used gas appliance can be determined, and the gas cutoff time can be set according to the presence or absence of the gas governor. The use state can be found at an early stage, the malfunction of the gas shutoff device can be reduced, and a more sophisticated gas safety shutoff function can be realized. For example, even if a similar minute flow rate is detected for a long time, “the gas is not shut off when a gas appliance equipped with a gas governor (for example, a fan heater) is used”, “the gas governor is not equipped When a gas appliance is used, it is determined that the gas is leaking and the gas is shut off. " In this way, it is possible to prevent a trouble that the gas is cut off accidentally although it is safe, or that the gas is not cut off when it is dangerous.

The present invention is not limited to the above embodiment,
For example, in the above embodiment, two safety continuation time tables are provided according to the presence or absence of the gas governor, and the shut-off time is set by changing the reference table according to the presence or absence of the gas governor. It is also possible to provide three or more safety continuation time tables according to the types of gas appliances that can be determined by the above, and change the table to be referred to according to the types of gas appliances that can be determined by the determination unit 48 to set the shut-off time. .

The means for determining the type of gas appliance to be used is not limited to the means described in the embodiment. For example, for each gas appliance, a detecting means for detecting the use of gas, such as a flame sensor, is provided. The type of the gas appliance to be used may be determined from the output of this detecting means.

[0060]

As described above, according to the gas shut-off device of the present invention, the storage means stores information indicating the relationship between the gas flow rate set for each type of gas appliance and the safety continuation time. The type of gas appliance being used is determined by the appliance determining unit, and the type of gas appliance and the individual flow rate calculated by the gas appliance determining unit are determined by the shutoff time setting unit using the information stored in the storage unit. Determining a safety duration based on the individual flow rate obtained by the means, and setting the safety duration as a cutoff time;
By the gas shutoff means, when the shutoff time set by the shutoff time setting means elapses from the start of use of the gas appliance, the supply of gas to the gas appliance is stopped. There is an effect that a shutoff time can be set and a more sophisticated gas safety shutoff function can be realized. In particular, the gas appliance discriminating means
A gas supply pressure for a gas appliance provided in the gas supply path
Gas pressure detection means for detecting force and active gas supply pressure
Pressure fluctuation means for dynamically changing the pressure,
Before and after pressure fluctuations
Pressure detection means when the gas flow rate
Therefore, the detected gas supply pressure and gas flow rate detection means
Used based on the detected gas flow rate
As the type of gas appliance, the gas of the gas appliance used
It is composed of a judging means for judging the presence or absence of governor equipment
So that the type of gas appliance can be effectively determined
be able to.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of a gas meter including a gas shutoff device according to one embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a control unit and its periphery in FIG. 1;

FIG. 3 is a functional block diagram showing functions of a gas shut-off device according to one embodiment of the present invention.

FIG. 4 is a flowchart showing the operation of the gas shut-off device according to one embodiment of the present invention.

FIG. 5 is a flowchart showing the operation of “flow rate ratio calculation” in FIG. 4;

FIG. 6 is a flowchart showing the operation of “gas appliance determination” in FIG. 4;

FIG. 7 is an explanatory diagram showing a membership function for fuzzy inference performed by the discriminating means in FIG. 3;

FIG. 8 is an explanatory diagram showing a membership function for fuzzy inference performed by the discriminating means in FIG. 3;

FIG. 9 is an explanatory diagram showing a membership function for fuzzy inference performed by the discriminating means in FIG. 3;

FIG. 10 is an explanatory diagram showing a membership function for fuzzy inference performed by the determination means in FIG. 3;

FIG. 11 is a flowchart showing an operation of “setting a cut-off time” in FIG. 4;

12 is a characteristic diagram illustrating an example of a relationship between a flow rate and a safety shut-off time, which is the content of a first safety continuation time table in FIG.

13 is a characteristic diagram showing an example of a relationship between a flow rate and a safety shut-off time, which is the content of a second safety continuation time table in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Gas meter 12 On-off valve 13 Gas shut-off valve 14 Gas pressure sensor 15 Gas flow meter 16 Control part

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01F 3/22

Claims (1)

(57) [Claims] 1. A storage means for storing information indicating a relationship between a gas flow rate set for each type of gas appliance and a safety continuation time, and a gas flow detection for detecting a gas flow rate passing through a gas supply path for the gas appliance. Means, when a change occurs in the gas flow rate detected by the gas flow rate detection means, calculates a change flow rate, and individual gas appliance flow rate calculation means for obtaining a flow rate for each individual gas appliance based on the change flow rate; Gas appliance discriminating means for discriminating the type of gas appliance being used, and using the information stored in the storage means, the type of gas appliance determined by the gas appliance discriminating means and the individual gas appliance flow rate calculating means A shut-down time setting means for determining a safety continuation time based on the obtained flow rate of each individual gas appliance and setting the safety continuation time as a shut-off time; When breaking time set by the cutoff time setting means from the use start has elapsed, a gas shut-off means for stopping the supply of gas to the gas appliance, the gas appliance determination unit is provided in the gas supply path, Moth
Gas pressure detecting means for detecting gas supply pressure to gas appliances
Stage and pressure varying means for actively varying the gas supply pressure
And before and after the pressure fluctuation by this pressure fluctuation means
Gas flow in the gas supply path is stable in
Sometimes the gas supply detected by the gas pressure detection means is
Supply pressure and gas detected by the gas flow rate detecting means
Based on the flow rate and the type of gas appliance used,
To determine whether the gas appliances used are equipped with a gas governor.
A gas cutoff device comprising: a discriminating means for discriminating .