JPH08261805A - Leak detector for gas meter - Google Patents

Abstract

PURPOSE: To detect the leakage of a gas in a short time without complicated work while allowing the measuring of the amount of a gas leaked. CONSTITUTION: A peak flow rate memory section 46 stores a peak flow rate in application per season of a gas apparatus connected to a gas meter. A leakage judging section 48 judges that the leakage of the gas occurs when a flow rate calculated by a flow rate computing section 44 exceeds the peak flow rate per season stored in the peak flow rate memory section 46 to display an alarm on a display part 45.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leak detecting device in a gas meter for detecting a gas leak in the gas meter.

[0002]

2. Description of the Related Art A conventional gas leak detection method in a gas meter with a safety function equipped with a microcomputer determines, for example, every hour whether or not there is a flow rate within one hour, and within one hour. For example, when the result of determination that there is a flow rate is continuous for 30 days, it is determined that there is a gas leak, and an alarm is displayed.

FIG. 4 and FIG. 5 each show an example of a flow rate change pattern due to the use of a gas appliance for 30 days, and an arrow 100 in the figure indicates the timing of determining the presence or absence of the flow rate every hour. ing. In the example of FIG. 4, 1
It is determined that there is no gas leakage during some time, so it is determined that there is no gas leakage. On the other hand, in the example of FIG. 5, the determination result that there is a flow rate for one hour continues for 30 days, and thus it is determined that there is a gas leak.

However, when the gas continues to flow for 30 days or more, in addition to the gas leakage, the gas appliance may be left ignited. for that reason,
In a conventional gas meter, in order to distinguish between gas leakage and igniting, the flow rate of igniting can be registered in a microcomputer. After registration of this igniting flow rate, the gas meter determines that the flow rate in the range of Q _E ± ΔQ is igniting, assuming that the registered igniting flow rate is Q _E , as shown in Fig. When it was detected continuously, it was judged that there was a gas leak. In addition, the registerable range of the ignition flow rate was, for example, 5.4 to 36.7 liters / hour.

[0005]

However, in the above-mentioned gas leakage detection method, it is necessary to detect gas leakage in 30
There was a problem that it took days. Further, there is a problem in that the gas leakage amount cannot be measured because the gas leakage is judged based on the judgment result as to whether or not there is a flow rate for one hour. In addition, it is necessary to register the igniting flow rate in order to distinguish between gas leakage and igniting, and if a gas appliance for which the igniting flow rate is not registered is used continuously, it must be judged as gas leakage. In order to avoid this, it is necessary for the user to stop the gas for one hour or more, and in any case the work was complicated.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a gas meter capable of detecting gas leakage in a short time without complicated work and capable of measuring the amount of gas leakage. It is to provide a leak detection device.

[0007]

A leak detection device in a gas meter according to claim 1 is provided in the gas meter,
The flow rate detection means for detecting the flow rate of gas, the peak flow rate storage means provided in the gas meter for storing the peak flow rate in the usage state of the gas instrument connected to the gas meter, and the flow rate detected by the flow rate detection means are peaks. Leakage determination means for determining gas leakage when the peak flow rate stored by the flow rate storage means is exceeded is provided.

In the leak detection device for this gas meter, the peak flow rate storage means stores the peak flow rate in the usage state of the gas appliance connected to the gas meter, and the leakage determination means uses the peak flow rate detected by the flow rate detection means. A gas leak is determined when the peak flow rate stored by the flow rate storage means is exceeded.

A leak detecting device for a gas meter according to a second aspect is the leak detecting device for a gas meter according to the first aspect, in which the peak flow rate storing means stores the peak flow rate for each season, and the leak determining means depends on the season. When the flow rate detected by the flow rate detection means exceeds the seasonal peak flow rate stored by the peak flow rate storage means, it is determined that a gas leak has occurred.

A leak detecting device for a gas meter according to a third aspect of the present invention is the leak detecting device for a gas meter according to the first or second aspect, wherein the flow rate detecting means includes a nozzle for ejecting a gas. A fluidic oscillation generation unit that generates fluidic oscillation, a fluidic oscillation detection sensor that detects the fluidic oscillation generated by this fluidic oscillation generation unit, and a flow rate is calculated based on the output of this fluidic oscillation detection sensor. And a flow rate calculating means for controlling the flow rate.

[0011]

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

FIG. 2 is a cross-sectional view showing the structure of a gas meter to which a leak detection device for a gas meter according to an embodiment of the present invention is applied. The gas meter comprises a body 10 having an inlet 11 for receiving gas and an outlet 12 for discharging gas. A partition wall 13 is provided in the main body 10, a gas flow channel 14 is formed between the partition wall 13 and the inlet portion 11, and a gas flow channel 15 is disposed between the partition wall 13 and the outlet portion 12.
Are formed. An opening 16 is provided in the partition wall 13, and a cutoff valve 17 capable of closing the opening 16 is provided in the gas flow path 14. A solenoid 18 is fixed to the outside of the body 10, and the plunger 1 of the solenoid 18 is fixed.
9 penetrates the side wall of the main body 10 and is joined to the shutoff valve 17. A spring 20 is provided around the plunger 19 between the shutoff valve 17 and the main body 10, and the spring 20 biases the shutoff valve 17 toward the opening 16.

In the gas passage 15, there is provided a nozzle 21 for passing the gas received from the inlet portion 11 to generate a jet flow. A flow sensor 30 which is a thermal type flow velocity sensor is arranged in the passage of the nozzle 21. Although not shown, the flow sensor 30 has a heat generating part and two temperature sensors arranged on the upstream side and the downstream side of the heat generating part, and keeps a constant temperature difference detected by the two temperature sensors. Therefore, the flow rate corresponding to the flow velocity is calculated from the power supplied to the heat generating section, or the heat generating section is heated with a constant current or constant power, and the flow rate is calculated from the temperature difference detected by the two temperature sensors. There is.

On the downstream side of the nozzle 21, a pair of side walls 23 and 24 forming an enlarged flow path are provided. A target 25 is provided on the upstream side and a target 26 is provided on the downstream side with a predetermined gap between the side walls 23 and 24. A return guide 29 is formed outside the side walls 23 and 24 to form a pair of feedback flow paths 27 and 28 for returning the gas passing 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. Is provided. A pair of discharge passages 31 and 32 are formed between the outlet portions of the feedback flow passages 27 and 28 and the outlet portion 12 by the back surface of the return guide 29 and the main body 10. A pressure guiding hole 3 is provided in the vicinity of the nozzle 21 ejection port.
3, 34 are provided, and a piezoelectric film sensor 35 (not shown in FIG. 2) for detecting the pressure difference between the pressure guiding hole 33 and the pressure guiding hole 34 is provided outside the bottom portion of the main body 10.

FIG. 1 is a block diagram showing the configuration of the circuit portion of the gas meter shown in FIG. As shown in this figure,
The gas meter is an A / D that converts the output signal of the flow sensor 30 from analog to digital (hereinafter referred to as A / D).
A converter 41, an analog amplifier 42 that amplifies the output signal of the piezoelectric film sensor 35, and a waveform shaping circuit 43 that shapes the output of the analog amplifier 42 to generate a pulse.
And a flow rate calculation unit 44 that inputs the output of the A / D converter 41 and the output of the waveform shaping circuit 43 and calculates the flow rate and the integrated flow rate based on at least one of the outputs according to the flow rate, and the flow rate calculation unit 44. And a display unit 45 that displays the integrated flow rate calculated by. The flow rate calculation unit 44 calculates the flow rate and the integrated flow rate based on the output of the A / D converter 41 in the small flow rate range in which the range is set in advance, and the waveform shaping circuit 43 in the large flow rate range in which the range is set in advance. Calculate the flow rate and integrated flow rate based on the output.

The gas meter further includes a peak flow rate storage unit 46 for storing a peak flow rate for each season in a usage state of a gas appliance connected to the gas meter, and a solenoid 18.
And a shut-off valve drive circuit 47 for driving the fuel cell, and when the flow rate calculated by the flow rate calculation section 44 exceeds the peak flow rate for each season stored by the peak flow rate storage section 46, it is determined that there is a gas leak, A leakage determination unit 48 that controls the shut-off valve drive circuit 47 to close the shut-off valve 17 to shut off the gas, and outputs an alarm display on the display unit 45, and a peak flow rate storage unit 4
6, an input unit 49 having a plurality of keys for setting the season when storing the peak flow rate. The flow rate calculation unit 44, the peak flow rate storage unit 46, and the leak determination unit 48 constitute a leak detection device in the gas meter according to this embodiment. The flow rate calculation unit 44, the peak flow rate storage unit 46, and the leakage determination unit 48 are configured by, for example, a microcomputer.

An outline of the operation of the gas meter shown in FIGS. 1 and 2 will be described.

The gas received from the inlet 11 of the gas meter is supplied to the gas passage 14, the opening 16 and the gas passage 1.
After going through 5 in order, it enters the nozzle 21. The output signal of the flow sensor 30 arranged in the passage of the nozzle 21 is converted into digital data by the A / D converter 41 and the flow rate calculation unit 4
4 is input. The flow rate calculation unit 44 is A /
The flow rate and the integrated flow rate are calculated based on the output of the D converter 41. The display unit 45 displays the integrated flow rate calculated by the flow rate calculation unit 44.

The gas passing through the nozzle 21 becomes a jet stream and is jetted from the jet outlet. The gas ejected from the ejection port flows along one side wall due to the Coanda effect. Here, it shall first flow 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 via the feedback flow path 27.
It is discharged from the outlet 12 via the discharge passage 31. At this time, the gas ejected from the nozzle 21 is changed in direction by the gas flowing through the feedback flow path 27, and now flows along the other side wall 24. This gas further passes through the feedback flow path 28, and the nozzle 21
Is discharged to the jet outlet side of the nozzle, and is discharged from the outlet portion 12 via the discharge passage 32. Then, the direction of the gas ejected from the nozzle 21 is changed by the gas flowing through the feedback flow path 28, and the gas flows again along the side wall 23 and the feedback flow path 27. By repeating the above operation, the gas passing through the nozzle 21 performs fluidic oscillation which alternately flows through the pair of feedback flow paths 27 and 28. The frequency of this fluidic oscillation,
The cycle has a relationship with the flow rate.

The fluidic oscillation is detected by the piezoelectric film sensor 35, the output of the piezoelectric film sensor 35 is amplified by the analog amplifier 42, pulsed by the waveform shaping circuit 43, and input to the flow rate calculation unit 44. The flow rate calculation unit 44 calculates the flow rate and the integrated flow rate based on the output of the waveform shaping circuit 43 in the large flow rate range.

Next, the operation of the leak detection device in the gas meter according to this embodiment will be described.

The leak detecting device in the gas meter according to the present embodiment first stores the peak flow rate in the peak flow rate storage section 46 after mounting the gas meter and then in the usage state of the gas appliance connected to the gas meter. Specifically, the start date (or month) and the end date (or month) of an arbitrary season are input using the input unit 49 to set the season, and the user is simultaneously used in the set season. A gas appliance which is a gas appliance that is used at the same time and has a peak gas flow rate when used at the same time. The flow rate calculated by the flow rate calculation section 44 at that time is checked by the leak determination section 48. The peak flow rate storage unit 46 stores the peak flow rate according to the set season. The above operation is performed for all seasons. The peak flow rate for each season is stored in this manner because the peak flow rate may be different depending on the season, such as the peak flow rate becomes larger in the winter season than in the summer season due to the use of the heating device. In addition,
The method of dividing the seasons is arbitrary. For example, November to April may be the winter season, and May to October may be the summer season, or the seasons may be finely divided. If the peak flow rate does not change throughout the year, only one peak flow rate that does not depend on the season may be stored. The peak flow rate is not limited to the sum of the flow rates used by all gas appliances connected to the gas meter, but is the maximum flow rate used in a combination of gas appliances used at the same time.

FIG. 3 shows an example of a daily gas usage pattern in winter. In this figure, reference character A is a gas flow rate using a stove, B is a gas flow rate using a table stove, C is a gas flow rate using a water heater,
D represents the gas flow rate when the bath is used. In this example, all gas appliances are not used at the same time and are labeled 5
As indicated by 0, the peak flow rate is A + C + D when the stove, the water heater and the bath are used at the same time.

After the peak flow rate for each season is stored in the peak flow rate storage section 46 as described above, the leak determination section 48 determines gas leakage. The leakage determination unit 48 has a calendar function of recognizing the date using a clock circuit of a microcomputer, and the peak flow storage unit 46 stores the peak flow rate in the season to which the date recognized by this calendar function belongs.
Then, the peak flow rate is compared with the flow rate calculated by the flow rate calculation unit 44. Then, the leakage determination unit 4
When the flow rate calculated by the flow rate calculation unit 44 exceeds the peak flow rate, the reference numeral 8 determines that the gas is leaking and issues an alarm display on the display unit 45. In addition, the leakage determination unit 48 includes the flow rate calculation unit 44.
The flow rate calculated by subtracting the peak flow rate from the calculated flow rate is displayed on the display unit 45 as the gas leakage amount.

As described above, according to this embodiment,
The peak flow rate for each season is stored, and when the flow rate calculated by the flow rate calculation unit 44 exceeds the peak flow rate for each season, it is determined that there is a gas leak. Gas leaks can be detected in time. Further, since the peak flow rate can be changed according to the season, it is possible to accurately determine whether or not there is a gas leak even when the peak flow rate varies depending on the season. Further, it is not necessary to register the igniter flow rate for each gas appliance in order to distinguish between igniting gas and gas leakage, or to stop the gas appliance for one hour or more. It is also possible to measure the amount of gas leakage.

The present invention is not limited to the above embodiment,
For example, when the flow rate used for each gas appliance is known as a numerical value, the peak flow rate may be numerically input together with the season setting using the input unit 49 and stored in the peak flow rate storage unit 46. .

[0027]

As described above, according to the leak detection device for a gas meter according to any one of claims 1 to 3, the peak flow rate storage means allows the peak in the usage state of the gas appliance connected to the gas meter. Since the flow rate is stored and the flow rate detected by the flow rate detection means exceeds the peak flow rate stored by the peak flow rate storage means, the leak determination means determines that the gas is leaked. The gas leakage can be detected by the method described above, and the gas leakage amount can be measured by the flow rate detected by the flow rate detecting means and the peak flow rate stored by the peak flow rate storing means.

Further, according to the leak detecting device in the gas meter of the second aspect, the peak flow rate storing means stores the peak flow rate for each season, and the leak determining means detects the flow rate detecting means according to the season. Since the gas leakage is judged when the flow exceeds the seasonal peak flow stored by the peak flow storage means, in addition to the above effect, it is judged whether or not the gas leak occurs even when the peak flow varies depending on the season. There is an effect that can be performed accurately.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of a gas meter to which a leak detection device in a gas meter according to an embodiment of the present invention is applied.

FIG. 2 is a cross-sectional view showing a configuration of a gas meter to which a leak detection device in a gas meter according to an embodiment of the present invention is applied.

FIG. 3 is an explanatory diagram showing an example of a daily gas usage pattern in winter.

FIG. 4 is an explanatory diagram showing an example of a flow rate change pattern due to use of a gas appliance for 30 days.

FIG. 5 is an explanatory diagram showing another example of a flow rate change pattern due to the use of a gas appliance for 30 days.

FIG. 6 is an explanatory diagram for explaining a gas leakage detection method in a conventional gas meter.

[Explanation of symbols]

 44 flow rate calculation unit 45 display unit 46 peak flow rate storage unit 47 shutoff valve drive circuit 48 leakage determination unit 49 input unit

Claims (3)

[Claims] 1. A flow rate detecting means provided in a gas meter for detecting a flow rate of gas, and a peak flow rate storing means provided in the gas meter for storing a peak flow rate in use of a gas instrument connected to the gas meter. A leak detecting device in a gas meter, comprising: leak determining means for determining a gas leak when the flow rate detected by the flow rate detecting means exceeds the peak flow rate stored by the peak flow rate storing means. 2. The peak flow rate storage means stores the peak flow rate for each season, and the leakage determination means changes according to the season.
2. The leak detection device for a gas meter according to claim 1, wherein when the flow rate detected by the flow rate detecting means exceeds the seasonal peak flow rate stored by the peak flow rate storing means, it is determined that a gas leak has occurred. 3. The flow rate detecting means includes a nozzle for ejecting gas, and a fluidic oscillation generator for generating fluidic oscillation by the gas ejected from the nozzle, and a fluidic oscillation generator for generating the fluidic oscillation. The leak detection in the gas meter according to claim 1 or 2, further comprising: a fluidic oscillation detection sensor for detecting fluidic oscillation, and a flow rate calculation means for calculating a flow rate based on an output of the fluidic oscillation detection sensor. apparatus.