JP2000230847A - Gas meter and gas supply control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable judging the state of application of a gas apparatus and perform suitably gas supply control in accordance with the state of application of the gas apparatus. SOLUTION: A judging part of a valve switching control part 161 monitors the value of flow rate, and judges whether the change of flow rate exists. The change is caused by a transient response of a gas apparatus wherein the flow rate temporarily increases in a specific period, in accordance with the state of application of the gas apparatus, and then turns to the state of decrease. By this judgment, the state of application of the gas apparatus is judged. On the basis of the judged result of the state of application of the gas apparatus, and the flow rate of gas, supply control of gas is performed. When it is judged that the gas apparatus is not used and gas leakage is possible, the judging part supplies a valve operating signal 165 to a valve driving part 150, drives an isolation valve 140, and cuts off a gas channel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a gas meter having a function of detecting leakage of gas flowing through a flow path and a gas supply control method.

[0002]

2. Description of the Related Art In recent years, gas meters using a flow meter such as a membrane type flow meter or a fluidic flow meter have been put into practical use. Recently, however, the flow rate of gas flowing through a flow passage has been almost continuously maintained for a predetermined time. 2. Description of the Related Art There is known a gas meter equipped with a microcomputer having a safety function of determining that an abnormality has occurred when the temperature is constant and shutting off a gas flow path. here,
“The gas flow rate is substantially constant” means that the change amount of the gas flow rate passing through the gas meter does not exceed, for example, 3%, and the microcomputer determines that the state within this range is a predetermined time (hereinafter referred to as “the gas flow rate”). , Continuous usable time), the safety valve is closed and the flow path is shut off, assuming that an abnormality such as gas leakage has occurred. On the other hand, when the change amount of the gas flow rate exceeds the above range or when the gas flow rate becomes 0, the microcomputer resets the built-in monitoring timer,
From that point, the continuous usable time is counted up again.

According to this type of gas meter, it is possible to detect an abnormality such as gas leakage in various gas combustion devices and pipes connected to the gas meter, thereby improving safety.

[0004] Conventionally, gas combustion control of gas appliances is performed by turning on and off the combustion itself in many cases. For this reason, if the combustion state of any gas equipment connected downstream of the gas meter changes,
The variation of the gas flow rate detected by the gas meter greatly exceeds the above range, and at this time, the monitoring timer of the microcomputer is reset almost without exception. For this reason, there is almost no possibility of an erroneous shut-off operation in which the gas flow rate is determined to be within the above range and the safety valve is closed and the flow path is shut off even though the gas appliance is actually used.

[0005]

However, recently,
For example, as in the case of an air-conditioning gas appliance such as a hot-water circulation type floor heating system or a gas heat pump (GHP), a gas that does not perform the on / off control as described above but proportionally controls a gas combustion amount according to a required heat amount. Equipment is increasing. In this type of gas equipment, gas combustion often continues for a long time, and the gas usage does not fluctuate as much as the conventional on-off control type gas equipment. There is a possibility of being shut off accidentally as an abnormality such as gas leakage. In addition, the hot water circulation type floor heating system means that hot water is produced by burning gas with a heat source device such as a GCH (gas central heating) boiler, and this hot water is circulated to a floor heating panel laid on the floor to make the room indoors. Is a heating system.

As described above, in the conventional gas meter, when the proportional control type gas equipment is used for a long time, the continuous use time has been exceeded even though no abnormality such as gas leakage has occurred. There is a possibility that the gas flow path may be shut off upon judgment, which is inconvenient for the user.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to make it possible to determine the use state of gas equipment and to appropriately control the supply of gas according to the use state of gas equipment. To provide a gas meter and a gas supply control method capable of performing the above.

[0008]

According to a first aspect of the present invention, there is provided a gas meter, comprising: a flow rate detecting means for detecting a flow rate of a gas flowing through a gas flow path; By determining whether there is a flow rate change that temporarily increases within a predetermined period and then turns to decrease according to the state, a determination unit that determines the use state of the gas appliance, and a determination result by the determination unit. Control means for controlling gas supply based on the gas flow rate detected by the flow rate detection means.

In this gas meter, it is determined based on the flow rate detected by the flow rate detecting means whether or not there is a flow rate change that temporarily increases within a predetermined period and then starts decreasing in accordance with the use state of the gas appliance. Then, the use state of the gas appliance is determined. Further, by the control means, based on the determination result of the use state of the gas appliance and the detected gas flow rate,
Gas supply control is performed.

According to a second aspect of the present invention, there is provided a gas meter according to the first aspect, further comprising a gas flow rate and a continuously usable time indicating a time during which the gas can be used continuously. With a time table, the control means, when it is determined that the gas equipment is not used by the determination means, to obtain a usable time corresponding to the gas flow rate by referring to the continuous available time table,
It has a function of determining that there is a leak in the gas flow path on condition that the amount of change in the gas flow rate is within a predetermined range over the obtained usable time.

In this gas meter, the control means
When the determination unit determines that the gas appliance is not used, the available time corresponding to the gas flow rate is acquired by referring to the continuous available time table, and the amount of change in the gas flow rate is used as the obtained usage. It is determined that there is a leak in the gas flow path on condition that the gas flow path is within a predetermined range for a possible time.

According to a third aspect of the present invention, in the gas meter according to the second aspect, when the control means determines that the gas appliance is used, the continuous usable time in the continuous usable time table is extended. Thus, the continuous use time table is changed to determine whether there is a leak in the gas flow path.

In this gas meter, the control means
If the determination unit determines that the gas appliance is being used, the continuous usable time table is changed so that the continuous usable time in the continuous usable time table is extended, and leakage to the gas flow path is performed. A determination is made as to whether there is a location.

According to a fourth aspect of the present invention, there is provided the gas meter according to the second or third aspect, wherein the control means supplies the gas so as to shut off the gas flow path when it is determined that there is a leak in the gas flow path. The control is performed.

In this gas meter, when the control means determines that there is a leak in the gas flow path, the supply of gas is controlled so that the gas flow path is shut off.

According to a fifth aspect of the present invention, a gas supply control method detects a flow rate of a gas flowing through a gas flow path, and temporarily increases the flow rate within a predetermined period according to a use state of a gas appliance based on the detected flow rate. After that, by determining whether there is a flow rate change that turns to decrease, determine the use state of the gas equipment,
The supply of gas is controlled based on the determination result of the usage state of the gas appliance and the detected gas flow rate.

In this gas leak detection method, it is determined based on the detected flow rate whether or not there is a flow rate change that temporarily increases within a predetermined period and then turns to decrease in accordance with the use state of the gas appliance. The use state of the gas appliance is determined.
Further, gas supply control is performed based on the determination result of the usage state of the gas appliance and the detected gas flow rate.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a schematic configuration of a main part of a gas meter according to an embodiment of the present invention. The gas meter according to the present embodiment can detect gas leakage in a gas flow path to which at least one gas device is connected on the downstream side, and can perform gas supply control. In the present embodiment, as an example of a gas meter, an example in which a measuring mechanism using a flow sensor and a measuring mechanism using a fluidic element are provided side by side will be described.

As shown in FIG. 1, the gas meter according to the present embodiment includes a piezoelectric film sensor 101 for detecting fluidic oscillation (described later) of a fluidic element which is in charge of detecting a flow rate in a large flow rate range, and a low flow rate sensor. Measuring unit 100 having a flow sensor 102 for detecting the flow rate of the area, a display 120 for displaying the integrated flow rate value, and a gas flow path in the gas meter if necessary (not shown in this drawing). ), A valve driving unit 150 for driving the shut-off valve 140, and a control unit 160 for controlling the entire gas meter.

The control section 160 includes a valve opening / closing control section 161 connected to an input end of the valve driving section 150 and a weighing mechanism section 100.
The flow calculation unit 162 is connected to the piezoelectric film sensor 101 and the flow sensor 102, and the integration unit 163 is connected to the output terminal of the flow calculation unit 162.

The valve opening / closing controller 161 includes a flow rate calculator 162
It is determined whether or not to shut off the flow path based on the flow rate value 166 from the controller.
Is to be closed. The flow rate calculation section 162 binarizes the flow rate signals from the piezoelectric film sensor 101 and the flow sensor 102 of the metering mechanism section 100, and calculates and outputs a flow rate value 166 based on one or both of these signals. It has become. Integrator 163 integrates flow value 166 from flow calculator 162 and outputs the integrated value to display 120.

The control unit 160 is constituted by using, for example, a microcomputer, and a ROM (Read Only
The memory is operated by executing a program stored in the memory or the like. Here, the weighing mechanism 1
00 and the flow rate calculating section 162 correspond to the “flow rate detecting means” in the present invention, and the shutoff valve 140 and the valve driving section 150
Corresponds to the "flow path blocking means" in the present invention. The valve opening / closing control unit 161 corresponds to the “determination unit” and the “control unit” in the present invention.

The display 120 is, for example, a liquid crystal display (LC).
D), and is configured to display a flow rate integrated value or the like output from the control unit 160.

FIG. 2 shows the valve opening / closing controller 161 in FIG.
Of FIG. As shown in this figure,
The valve opening / closing control unit 161 includes a determination unit 161a to which the flow rate value 166 from the flow rate calculation unit 162 is input, and a determination unit 16
It has a continuous usable time table 161b and a timer 161c connected to 1a.

The determination unit 161a monitors the value of the flow rate value 166 and determines whether there is a flow rate change due to the transient response of the gas appliance which temporarily increases within a predetermined period and then starts decreasing according to the use state of the gas appliance. By determining whether the gas equipment is in use, the use state of the gas equipment is determined, and the supply of gas is controlled based on the determination result of the use state of the gas equipment and the gas flow rate. More specifically, the determination unit 161
a, it is determined that the gas appliance is not used, and when a predetermined condition described later is satisfied, it is determined that there is a possibility of gas leakage, and the valve driving signal 165 is transmitted to the valve driving unit 15.
0 to drive the shutoff valve 140 to shut off the gas flow path. The determination of the transient response of the gas appliance will be described later in detail with reference to FIG.

The continuous usable time table 161b is, for example, as shown in FIG. 3, in which continuous usable time is set in association with each range of the individual flow rate. It is being referred to. Here, the individual flow rate is defined as a value obtained by integrating the flow rate value 166 from the flow rate calculation unit 162 for a fixed time τ (for example, 30 seconds) at a time exceeding a certain range (for example, 3%). Is the amount of change in the flow rate per unit time obtained by calculation from the difference between the previous integrated value and the current integrated value. For example, in the example shown in FIG.
The quantity shown in Q3 corresponds to this. Note that FIG. 4 shows the average flow rate per unit time based on the integrated flow rate value for each fixed time τ and represents the average flow rate per time τ, and does not represent the real time change of the flow rate. In FIG. 4, the horizontal axis represents time, and the vertical axis represents the average flow rate for each time τ.

In FIG. 3, the continuous usable time is the time during which continuous gas use is recognized, and the length thereof is set to a different value according to the magnitude of the individual flow rate. More specifically, when the gas is continuously used so as not to exceed a predetermined flow rate fluctuation range (for example, 3% or less), the flow path is shut off when the corresponding individual flow rate in FIG. 3 is reached. Is the continuous usable time.
In the example shown in FIG. 3, the range of the individual flow rate is a range in which the maximum flow rate value (liter / hour) determined by the number of the meter is an upper limit, and is 0 to 50 liter / hour and 50 to 500 liter.
L / h, 500-1000 l / h, 100
It is classified into six types: 0 to 2000 liters / hour, 2000 to 3000 liters / hour, and 3000 to the maximum flow rate value liters / hour according to the number of meters. The continuous usable time is, for example, corresponding to the range of these individual flow rates,
Unlimited time, 720 minutes, 360 minutes, 120 respectively
Minutes, 60 minutes and 30 minutes. Here, the continuous usable time table 161b corresponds to the “continuous usable time table” in the present invention.

The timer 161c is for measuring the elapsed time (gas use time) starting from the time of the change when a certain individual flow rate is changed to another individual flow rate. Is reset by the start signal, and the timer operation is started.

FIG. 5 shows a sectional structure of the weighing mechanism 100 shown in FIG. This weighing mechanism section 100
Inlet 11 for receiving gas and outlet 1 for discharging gas
2 is provided. A partition 13 is provided in the main body 10, a first gas flow path 14 is formed between the partition 13 and the inlet 11, and the partition 13 and the outlet 12
A second gas flow path 15 is formed between the second gas flow path and the second gas flow path. Partition wall 1
An opening 16 is provided in 3, and the above-described shutoff valve 140 (FIG. 1) is provided in the first gas channel 14 so as to close the opening 16. A valve driving unit 150 (FIG. 1) made of a solenoid or the like is fixed to the outside of the main body 10,
The plunger 19 of the valve driving section 150 penetrates the side wall of the main body 10 and is connected to the shutoff valve 140. A spring 20 is provided around the plunger 19 between the shutoff valve 140 and the main body 10, and the spring 20 urges the shutoff valve 140 toward the opening 16. During normal use, the solenoid of the valve drive unit 150 is kept energized, and the shutoff valve 140 is separated from the opening 16.

In the second gas passage 15, there is provided a nozzle 21 for passing the gas received from the inlet 11 to generate a jet. A rectifying member 22 for adjusting the flow of gas is provided upstream of the nozzle 21. Downstream of the nozzle 21, a pair of side walls 23 and 24 that form an enlarged flow path are provided. This side wall 2
A predetermined interval is left between 3, 24, and the first
A target 25 and a second target 26 are provided on the downstream side, respectively. In addition, outside the side walls 23 and 24,
A return guide 2 that forms a pair of feedback flow paths 27 and 28 that return the gas that has passed through the nozzle 21 to the ejection port side of the nozzle 21 along the outer peripheral portions of the side walls 23 and 24.
9 are provided. Also, the feedback channel 27,
28, a pair of discharge paths 3 is provided between the outlet portion 12 and the outlet portion 12 by the back surface of the return guide 29 and the main body 10.
1, 32 are formed. In the vicinity of the ejection port of the nozzle 21, pressure guiding holes 33 and 34 are provided to communicate with a piezoelectric film sensor for detecting a change in the direction of flow of the gas passing through the nozzle 21.

The flow sensor 1 is provided in the passage of the nozzle 21.
02 is provided. The flow sensor 102 is configured as, for example, a thermal flow sensor having a heat generating portion and two temperature sensors disposed before and after the heat generating portion.

FIG. 6 is an enlarged cross-sectional view of the main body 10 including the pressure guiding holes 33 and 34 in FIG. As shown in this figure, a piezoelectric film sensor 101 is provided outside the bottom of the main body 10. Further, one ends of pressure guiding tubes 51 and 52 are connected to the pressure guiding holes 33 and 34, respectively. The other end of each of the pressure guiding tubes 51 and 52 is connected to each pressure inlet of the piezoelectric film sensor 101. Then, by the piezoelectric film sensor 101, the pressure guiding holes 33 and the pressure guiding holes 3 are formed.
4, the fluid pressure oscillation is detected based on the change in the pressure difference. In addition,
The pressure guiding tubes 51 and 52 and the piezoelectric film sensor 101 are
0 is covered by a case 55 fixed to the outside of the bottom.

Next, referring to FIG. 7, the judgment section 161a
A method for determining the transient response of the gas appliance in FIG. 2 will be described. In this figure, the vertical axis indicates the instantaneous flow rate, and the horizontal axis indicates time. As shown in this figure, for example, in a gas appliance of the proportional control method, a flow rate change having a transient response in which the flow rate temporarily increases and then starts decreasing as shown by a curve 212 in the figure is observed. Is done. On the other hand, in a gas appliance that turns on / off the combustion itself instead of proportional control, a change in the flow rate as indicated by a curve 211 in the figure is observed. The determining unit 161a determines the usage state of the gas appliance based on such a difference in the flow rate change.

For example, as shown in (A) in the figure, the determination unit 161a determines that the flow rate within a predetermined period T1 (for example, about 1 minute) is changed to “flow increase period T11 (for example, about 10 seconds)” → If there is a change from “flow reduction period T12 (for example, about 30 seconds)” to “flow rate stabilization period T13 (for example, about 20 seconds)”, a transient response in the case of using a gas appliance by a proportional control method or the like. Is determined. In addition, the period T12 in which the flow rate decreases is slightly changed depending on the required amount of heat. On the other hand, as shown in FIG.
“Flow increase period T21 (for example, about 10 seconds)” →
“Flow rate stabilization period T22 (for example, about 30 seconds)” →
If there is a change in the flow rate “the flow rate stabilization period T23 (for example, about 20 seconds)”, it is determined that the response is not a transient response due to the use of gas equipment. Note that the flow rate stabilization period T
The period 22 changes somewhat depending on the required amount of heat. Here, it is determined whether or not the flow rate is increasing (decreasing), for example, by comparing adjacent flow rate determination units, and when the difference in the flow rate increases (decreases) by 3% or more, the flow rate increases. (Decrease) can be determined. The determination as to whether the flow rate is stable can be made, for example, by comparing adjacent flow rate determination units and determining that the flow rate is stable when the difference between the flow rates is within 3%. In addition,
The “flow rate determination unit” corresponds to, for example, one cycle of fluidic oscillation in the case of a fluidic flow meter.

The reason why the above-described transient response occurs in the proportional control type gas appliance is as follows. That is, in the early version of the proportional control type gas appliance, the proportional valve was opened according to the amount of heat at the time of ignition. After a while, a failure occurred in which the proportional valve was fixed in a closed state, and the failure was improved by once fully opening the proportional valve at the time of ignition. Due to such circumstances, in the proportional control type gas equipment, the proportional valve is generally fully opened once regardless of the amount of heat, which causes a transient response.

Next, the operation of the gas meter configured as described above will be described.

First, the operation of the gas meter for measuring and displaying the flow rate will be described. In FIG. 5, the weighing mechanism 1
The gas received from the inlet 11 of the first nozzle 00 passes through the first gas flow path 14, the opening 16, the second gas flow path 15, and the rectifying member 22 in this order, and enters the nozzle 21. The gas that has passed through the nozzle 21 is jetted from the jet port as a jet. The gas ejected from the ejection port flows along one side wall due to the Coanda effect. Here, it is assumed that the flow first flows along the side wall 23. The gas flowing along the side wall 23 is further returned to the ejection port side of the nozzle 21 through the feedback channel 27 and is discharged from the outlet section 12 through the discharge path 31. At this time, the direction of the gas ejected from the nozzle 21 is changed by the gas flowing through the feedback flow path 27, and the gas flows along the other side wall 24 this time. This gas is further returned to the ejection port side of the nozzle 21 through the feedback channel 28 and discharged from the outlet section 12 through the discharge channel 32. Then, the direction of the gas ejected from the nozzle 21 is changed by the gas flowing through the feedback channel 28, and the side wall 2
3. Flow along the feedback flow path 27. By repeating the above operation, the gas that has passed through the nozzle 21 performs fluidic oscillation that alternately flows through the pair of feedback channels 27 and 28. The frequency and period of this fluid oscillation have a correspondence with the flow rate,
Detected by the piezoelectric film sensor 101 (FIG. 6) and output as a flow rate signal, the flow rate calculation unit 162 of the control unit 160
(FIG. 1).

On the other hand, the flow sensor 102 generates a temperature difference between two temperature sensors (not shown) in accordance with the flow rate of the gas flowing therethrough when a heating section (not shown) is heated with a constant current or a constant power. Is output as a flow rate signal and input to the flow rate calculation unit 162.

In FIG. 1, when the flow rate is in a large flow rate range suitable for measurement by a fluidic element, a flow rate calculation unit 162 uses a flow rate signal from the piezoelectric film sensor 101 and the flow rate is suitable for measurement by the flow sensor 102. When the flow rate is in the small flow rate range, the flow rate is calculated using the flow rate signal from the flow sensor 102. Specifically, when using the piezoelectric film sensor 101, the flow rate calculation unit 162
A pulse is generated based on the flow rate signal from the controller, the number of pulses per unit time is counted, a frequency of the fluidic oscillation is obtained, and this frequency is converted into a flow rate. On the other hand, when the flow sensor 102 is used, the number of pulses per unit time of the flow signal from the flow sensor 102 is counted to determine the flow rate. When the flow rate is in a region where the large flow rate area and the small flow rate area intersect, the flow rate calculation unit 162 may calculate the flow rate from one of the outputs,
The flow rate may be obtained by an operation (for example, taking an average value) using both outputs. Or Japanese Unexamined Patent Publication
As described in JP-96817-A, the piezoelectric film sensor 1
Flow sensor 1 based on the measured value from the output from
02 may be calibrated.

The flow value 166 obtained by the flow calculating section 162 is sent to the integrating section 163 and also to the valve opening / closing control section 161. The integrating section 163 integrates the flow value 166 to obtain a flow integrated value, and displays the integrated value on the display 12.
Send to 0 for display. On the other hand, the valve opening / closing control unit 161
In addition to checking the value of the input flow rate value 166, the presence or absence of the input of the detection signal 167 from the signal receiving unit 164 is checked, and according to the result, it is determined whether or not the gas valve is shut off by the shutoff valve 140. Do.

Next, with reference to FIG. 8, the operation of the gas meter for shutting off the flow path will be described. The following description also serves as a description of the gas supply control method according to the present embodiment.

FIG. 8 mainly shows the operation of the determination section 161a (FIG. 2) in the valve opening / closing control section 161.
The determination unit 161a of the valve opening / closing control unit 161 checks the flow value 16 from the flow rate calculation unit 162 in order to check the usage state of the gas.
6 is constantly monitored to determine whether or not gas has started flowing (step S101). If gas has not started flowing (N), this determination is repeated. When the gas starts to flow (Step S101; Y), the predetermined period T
1 to obtain the instantaneous flow rate (step S102),
It is checked whether or not there is a transient response in which the flow rate temporarily increases and then starts to decrease (step S103). The determination as to whether or not the response is a transient response is as described above with reference to FIG.

When no transient response is observed (step S
103; N), the determination unit 161a calculates an individual flow rate (step S104). The calculation of the individual flow rate is, as described with reference to FIG.
66 in a fixed range (here, 3
%), A change in the average flow rate per unit time is obtained from the difference between the previous integrated value and the current integrated value. For example, when the use of gas is started, ΔQ1 in FIG. 4 is the individual flow rate.

Next, the determining unit 161a refers to the continuous available time table 161b (FIG. 3) to obtain the continuous available time T corresponding to the calculated individual flow rate, and starts the timer 161c. A signal is sent, the timer 161c is reset, and a timer operation is started (step S105).

Thereafter, based on the flow rate value 166 from the flow rate calculation section 162, the determination section 161a determines whether or not the integrated value of the flow rate value 166 has changed by a certain range (here, 3%) or more for each fixed time τ. Is monitored (step S10).
At the same time as 6), it is monitored whether or not the gas usage time has exceeded the continuous usable time T based on the time count value from the timer 161c (step S107). Here, when the state where the integrated value of the flow rate value 166 for each fixed time τ is within a certain range (here, 3%) continues over the continuous usable time T (step S106; N, step S107; Y). The determination unit 161a determines that the individual flow rate is not due to the use of the gas equipment but to the occurrence of an abnormality such as gas leakage, and sends the valve drive signal 150 to the valve drive unit 150.
5 to drive the shutoff valve 140 to shut off the gas flow path (step S108). On the other hand, the flow rate value 16
If the integrated value for each fixed time τ in step 6 exceeds the fixed range (step S106; Y), the flow returns to step S102 to acquire the instantaneous flow rate within the predetermined period T1 again.
Step S103 and subsequent steps are performed.

For example, in FIG. 4, assuming that the individual flow rate ΔQ1 at the beginning t1 when the gas is used is, for example, 800 liters / hour, the continuous usable time T becomes 360 minutes by referring to the continuous usable time table 161b. At the same time, the timer 161c is reset and the timer operation is started (step S105), and the time-up of the continuous usable time of 360 minutes is monitored (steps S106 and S107). Further, assuming that the flow rate subsequently changes and the individual flow rate ΔQ2 at time t2 is, for example, 400 liters / hour, the continuous usable time T is 720
The timer is set to minutes and the timer 161c is reset to resume the timekeeping operation, and the continuous usable time of 720 minutes is monitored. In these cases,
When the continuous use time T has elapsed, the gas flow path is shut off by the shutoff valve 140 (step S108).

On the other hand, when a transient response is observed (step S103; Y), the determination unit 161a determines that the change in the flow rate is the use of a gas appliance or the like by a proportional control method with a proportional valve (step S103). In step S109, for example, the continuous available time T is changed and set to be unlimited regardless of the value of the individual flow rate so that the continuous available time T set in the continuous available time table 161b is extended (step S110). ), And returns to the processing of step S101 and subsequent steps.

As a method for extending the continuous usable time, for example, the continuous usable time of, for example, several hours is uniformly applied to all the continuous usable times for each individual flow rate range in the continuous usable time table 161b. A method such as addition may be adopted. In this case, when the state in which the integrated value of the flow rate value 166 for each fixed time τ is within a certain range (for example, 3%) continues over the extended continuous usable time T, the determination unit 161a determines Valve drive unit 150
By outputting the valve drive signal 165 to the shut-off valve 140
Is driven to shut off the gas flow path.

As described above, according to the present embodiment, the determination unit 161a monitors the value of the flow rate value 166, and temporarily increases within a predetermined period according to the usage state of the gas equipment and then decreases. By determining whether there is a change in the flow rate due to the transient response of the gas equipment, the usage state of the gas equipment is determined, and the gas usage is determined based on the determination result of the usage state of the gas equipment and the gas flow rate. Since the supply control of the gas equipment is performed, it is possible to determine the use state of the gas equipment, and it is possible to appropriately control the gas supply according to the use state of the gas equipment. That is, it is possible to determine whether the gas appliance is used or not, and it is possible to appropriately detect gas leakage according to the usage state of the gas appliance. Therefore, it is possible to shut off the gas flow path only when the gas equipment is not used. For example, even when using gas equipment that may perform proportional control of the combustion amount within a certain range (within 3%), such as a hot water circulation floor heating system or gas heat pump, the detected flow rate is It can be distinguished whether it is due to the use of equipment or due to gas leakage. Accordingly, it is possible to prevent the gas flow path from being erroneously shut off when the proportional control type gas equipment is used for a long time.

Further, even in the case of using, for example, a low-flow-rate gas appliance in which a transient response is not observed, the gas passage is cut off by determining the gas leakage using the continuous usable time table 161b. Can be improved more than before.

The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in the above embodiment, the gas meter using both the flow signal obtained from the piezoelectric film sensor 101 for detecting the fluidic oscillation of the fluidic element and the flow signal obtained from the flow sensor 102 has been described. The present invention is not limited to this, and can be applied to, for example, a device using only a fluidic element or a device using only the flow sensor 102. Further, the present invention is applicable to gas meters using other types of flow meters as long as the instantaneous flow rate can be measured with the accuracy required to determine the transient response of gas equipment, such as a turbine type flow meter.

[0053]

As described above, claims 1 to 4
According to the gas meter according to any one of the above or the gas supply control method according to the fifth aspect, the flow rate of the gas flowing through the gas flow path is detected, and based on the detected flow rate, according to the usage state of the gas appliance. By determining whether there is a change in the flow rate that temporarily increases within a predetermined period and then turns to decrease, the use state of the gas appliance is determined, and the use state determination result of the gas appliance and the detected gas are determined. Since the gas supply control is performed based on the flow rate, it is possible to determine the usage state of the gas equipment and to appropriately perform the gas supply control according to the usage state of the gas equipment. It has the effect of being able to. Therefore, for example, even when the combustion amount control is performed in a range that is considered to be almost constant in a proportional control type gas appliance, whether the detected gas flow rate is due to gas combustion or gas leakage. Can be discriminated. As a result, it is possible to eliminate the problem that the gas flow path is erroneously shut off when the proportional control type gas device is used for a long time as in the related art.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a gas meter according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a schematic configuration of a valve opening / closing control unit in the gas meter illustrated in FIG.

FIG. 3 is a diagram illustrating an example of a continuously usable time table in a valve opening / closing control section illustrated in FIG. 2;

FIG. 4 is a timing chart for explaining the operation of the gas meter shown in FIG.

FIG. 5 is a cross-sectional view illustrating a main structure of a metering mechanism in the gas meter illustrated in FIG.

FIG. 6 is an enlarged cross-sectional view illustrating a main structure of a metering mechanism in the gas meter illustrated in FIG.

FIG. 7 is an explanatory diagram showing a method of determining a transient response in a determination unit of the gas meter shown in FIG.

8 is a flowchart for explaining the operation of the gas meter shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 100 Measuring mechanism part 101 Piezoelectric film sensor 102 Flow sensor 140 Shut-off valve 150 Valve drive part 160 Control part 161 Valve opening / closing control part 161a Judgment part 161b Continuous usable time table 161c Timer 162 Flow rate calculation part

Claims (5)

[Claims] 1. A flow rate detecting means for detecting a flow rate of a gas flowing through a gas flow path, and a flow rate is temporarily increased within a predetermined period according to a use state of a gas appliance based on a flow rate detection result by the flow rate detecting means. After determining whether there is a change in the flow rate that turns to decrease, a determination means for determining the use state of the gas appliance, the determination result by this determination means and the gas flow rate detected by the flow rate detection means And a control means for controlling gas supply based on the gas meter. 2. The apparatus according to claim 1, further comprising: a continuously usable time table in which a gas flow rate is associated with a continuously usable time indicating a time during which the gas can be continuously used. When it is determined that the gas appliance is not used, the usable time corresponding to the gas flow rate is obtained by referring to the continuous usable time table, and the change in the gas flow rate indicates the obtained usable time. 2. The gas meter according to claim 1, further comprising a function of determining that there is a leak in the gas flow path on condition that the gas flow path is within a predetermined range. 3. The controller according to claim 1, wherein, when it is determined that the gas appliance is being used, the controller sets the continuous usable time table so that the continuous usable time in the continuous usable time table is extended. The gas meter according to claim 2, wherein a change is made to determine whether or not there is a leak in the gas flow path. 4. The gas supply control according to claim 2, wherein the control means controls the gas supply so as to shut off the gas flow path when it is determined that there is a leak in the gas flow path. The described gas meter. 5. A flow rate of a gas flowing through a gas flow path is detected, and based on the detected flow rate, there is a flow rate change that temporarily increases within a predetermined period and then decreases according to a use state of a gas appliance. Determining whether or not the gas device is in use, and performing gas supply control based on the determination result of the use condition of the gas device and the detected gas flow rate. Gas supply control method.