JPH0771991A - Gas meter - Google Patents

Abstract

PURPOSE:To enable a trace gas leakage to be detected in early stages. CONSTITUTION:When the flow rate of gas with which a gas appliance can be regarded as being an use as not measured by a gas flowmeter 13 for a predetermined time or more, a control part 15 shuts off a gas flow passage 11 by means of a gas shutoff valve 12 for a predetermined period of time and monitors the pressure of gas using a gas pressure sensor 14, thus detecting the fluctuation of the gas pressure. When the fluctuation of the gas pressure exceeds a preset value, the control portion 15 determines that a trace amount of gas is leaking.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas meter for measuring the flow rate of gas supplied upstream of a gas appliance such as a gas stove, and more particularly to a gas meter capable of detecting a slight gas leak.

[0002]

2. Description of the Related Art In recent years, as a gas meter for home use, a meter equipped with a microcomputer and a safety function in addition to the function of measuring the flow rate of passing gas has been put into practical use. The safety function of this gas meter is to detect the flow rate of gas above a predetermined amount using a flow meter, to detect the flow rate above a predetermined time for a certain period of time, or to supply a pressure above a predetermined pressure using a gas pressure detection sensor. When there is no pressure, it has a function of driving the gas shutoff valve to shut off the gas flow path. With these functions, leaks in piping and outflow of unnatural gas can be detected to prevent accidents.
It is designed to guarantee safety.

As a safety function of a gas meter equipped with a microcomputer, in addition to the above-mentioned function, there is a function of detecting a slight gas leak. The conventional gas meter has a function of detecting a small amount of gas leakage, for example, when a situation where the gas is not used for a predetermined time, for example, one hour or more cannot be detected for a predetermined number of days, for example, 30 days, a small amount of gas is detected on the downstream side of the gas meter. It was judged that there was a gas leak and shut off the gas.

[0004]

However, with the conventional function for detecting a small amount of gas leakage as described above, it takes a long period of 30 days to detect a small amount of gas leakage, and therefore a small amount of gas leakage is detected. There is a problem that it is not possible to detect it early.

The present invention has been made in view of the above problems, and an object thereof is to provide a gas meter which enables early detection of a slight gas leak.

[0006]

A gas meter according to claim 1, wherein a gas passage through which a gas passes, a gas cutoff valve provided in the gas passage, for shutting off the gas passage, and a gas flow. A gas flow meter provided in the passage for measuring the flow rate of the gas passing through the gas passage, a gas pressure detection sensor provided in the gas passage for detecting the pressure of the gas in the gas passage, and a predetermined time As described above, when the gas flow rate at which it can be determined that the gas appliance is being used is not measured by the gas flow meter, the gas cutoff valve is driven to cut off the gas flow path for a predetermined period, and the gas pressure detection sensor is used. A gas pressure monitoring means for monitoring the pressure of the gas to detect a variation in the pressure of the gas, and a small amount when the variation in the pressure of the gas detected by the gas pressure monitoring means exceeds a preset value. Judge that there is a gas leak It is obtained by a cross section.

In this gas meter, when the gas flow rate at which it can be determined that the gas appliance is used is not measured by the gas flow meter for a predetermined time or longer, the gas pressure monitoring means shuts off the gas flow path for a predetermined period. The gas pressure is monitored by using the gas pressure detection sensor, and the fluctuation amount of the gas pressure is detected. Then, the judging means judges that a slight amount of gas leakage exists when the fluctuation amount of the gas pressure detected by the gas pressure monitoring means exceeds a preset value.

A gas meter according to a second aspect is the gas meter according to the first aspect, wherein the gas pressure monitoring means detects at least one of a decrease amount and a decrease gradient of the gas pressure in a predetermined period as a variation amount of the gas pressure. It is something that is done.

A gas meter according to a third aspect of the present invention is the gas meter according to the first or second aspect, further comprising warning means for issuing a warning when the determination means determines that a small amount of gas leakage is present.

In this gas meter, when the judging means judges that a slight amount of gas leakage exists, the warning means gives a warning.

The gas meter according to a fourth aspect of the present invention is the gas meter of the first aspect.
In the gas meter described in 2 or 3, further, when the judging means judges that a slight amount of gas leakage exists, the gas shutoff valve continues to shut off the gas flow path, and it is not judged that a minute amount of gas leakage exists. In this case, it is provided with a gas cutoff valve control means for opening the gas cutoff valve.

In this gas meter, when the judging means judges that a slight amount of gas leakage exists, the gas shutoff valve control means continues to shut off the gas flow path by the gas shutoff valve, and the judging means makes a slight gas leak. If it is not determined that the gas shutoff valve is present, the gas shutoff valve control means opens the gas shutoff valve. As a result, when it is not determined that a slight amount of gas leakage exists, the gas appliance can be used as soon as the inspection for gas leakage is completed.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 to 4 relate to an embodiment of the present invention.

FIG. 1 is an explanatory view showing a schematic structure of a gas meter according to this embodiment. As shown in this figure, a gas flow passage 11 having a gas inlet 16 and a gas outlet 17 is provided inside the gas meter 10 of this embodiment. The gas 20 flows into the gas flow path 11 through a pipe (not shown), and the gas 20 is supplied to a gas appliance such as a gas stove (not shown). In the gas flow path 11, the gas flow path 1 is sequentially arranged from the gas inlet 16 side.
1, a gas shutoff valve 12 for shutting off 1, a gas flow meter 13 for measuring the flow rate of the gas passing through the gas flow path 11, and a gas pressure detection sensor 14 for detecting the pressure of the gas in the gas flow path 11. Is provided.

A control unit 15 is provided in the gas meter 10 for controlling the gas cutoff valve 12 and the like while receiving the outputs of the gas flow meter 13 and the gas pressure detection sensor 14.

FIG. 2 is a block diagram showing the configuration of the control unit 15 and its peripherals in the gas meter 10 of this embodiment.
As shown in this figure, the control unit 10 includes a CPU (central processing unit) 30, a ROM (read only memory) 31,
A RAM (random access memory) 32, a clock 33 for clocking time, and an input / output port 34 are provided, and these are connected to each other by a bus 35.
In addition to the gas flow meter 13 and the gas pressure detection sensor 14 described above, the input / output port 34 is connected to a drive circuit 36 that drives the gas cutoff valve 12 and a warning lamp 37 that warns the occurrence of a minute amount of gas leakage. Has been done.

In the control unit 15, the CPU 30 controls the RA
By executing a program stored in the ROM 31 with M32 as a working area, a safety function such as detection of a slight gas leak is realized.

As a function relating to detection of a slight amount of gas leakage, the control unit 15 has a predetermined period of time when a gas flow rate which can be determined to be a gas appliance is not measured by the gas flow meter 13 for a predetermined period of time or longer. , The gas shutoff valve 12 is driven to shut off the gas flow path 11, and the gas pressure detection sensor 1
4, the gas pressure monitoring means for monitoring the gas pressure to detect the variation of the gas pressure, and the variation of the gas pressure detected by the gas pressure monitoring means exceeds a preset value. In this case, a judgment means for judging that a minute amount of gas leak exists, a warning means for turning on the warning lamp 37 and issuing a warning when this judgment means judges that a minute amount of gas leakage exists, and a judgment means When it is determined that there is a gas leak, the gas shutoff valve 12 continues to shut off the gas flow path 11, and when it is not determined that a slight amount of gas leak exists, the gas shutoff valve 12 is opened. Each function of the means is provided.

Next, the operation of the gas meter of this embodiment will be described.

The gas meter of this embodiment is a gas flow meter 13
The gas flow rate of the gas passing through the gas flow path 11 is measured by the gas flow path 11
The pressure of the gas inside is detected. And
As in the conventional case, when the gas flow meter 13 detects a gas flow rate of a predetermined amount or more, when the predetermined gas flow rate is detected for a predetermined time or more, or when the gas pressure detection sensor 14 is used to supply a pressure of a predetermined pressure or more. It has a safety function of driving the gas shutoff valve 12 to shut off the gas flow path 11 when there is no pressure. In addition to these safety functions, the gas meter of this embodiment has a function of detecting a minute amount of gas leakage as described below.

FIG. 3 is a flow chart showing the operation of detecting a slight gas leak. In this operation, first, the control unit 15 measures, by the gas flow meter 13, the gas flow rate at which it can be determined that the gas appliance is unused, that is, the gas flow rate at which the user can determine that the gas appliance is being used in the normal usage state. It is determined whether or not the state not to be continued for a predetermined time (step S101). When it does not continue for the predetermined time (N), the above determination (step S101) is repeated. When it continues for a predetermined time (Y), the gas shutoff valve 12 is driven through the drive circuit 36 to shut off the gas flow path 11 for a predetermined period, and the gas pressure is detected by the gas pressure detection sensor 14 during that period. It is monitored (step S102). The pressure detected by the gas pressure detection sensor 14 at each time point within the predetermined period is stored in the RAM 32 in the control unit 15. Next, the control unit 15
Calculates a decrease amount and a decrease gradient of the gas pressure as a variation amount of the gas pressure in the predetermined period from the pressure at each time point in the predetermined period (step S103). Next, the control unit 15 determines whether or not there is a slight amount of gas leakage by determining whether or not at least one of the amount of decrease in the gas pressure and the decrease gradient exceeds a preset value ( Step S104). When there is a slight gas leak (Y), the control unit 15 continues to shut off the gas flow path 11 by the gas shutoff valve 12 and outputs a warning signal to turn on the warning lamp 37 (step S105). , Ends the operation. If a small amount of gas leakage does not exist (step S1
In 04; N), the control unit 15 restores or opens the gas cutoff valve 12 (step S106), and ends the operation.

FIG. 4 is a characteristic diagram for explaining a method of detecting a slight amount of gas leakage from the decrease amount and the decrease gradient of the gas pressure. The horizontal axis indicates that the gas cutoff valve 12 shuts off the gas flow passage 11. And the vertical axis represents the gas pressure. As shown in this figure, when there is a small amount of gas leakage due to a hole in the pipe on the downstream side of the gas meter 10, etc., the gas pressure increases as the elapsed time after the gas flow path 11 is blocked increases. I know it will drop. Therefore, in the present embodiment, the pressure of the gas is monitored within a predetermined period indicated by the symbol a in FIG. 4, the decrease amount and the decrease gradient of the gas pressure during the predetermined period a are calculated, and the decrease amount of the pressure of the gas is calculated. It is determined that a slight amount of gas leakage exists when at least one of the above and the decrease gradient exceeds a preset value. It is also possible to estimate the size of the hole from the size of the pressure drop gradient. Since the decrease gradient of the gas pressure has a negative value, the decrease gradient of the gas pressure exceeding the preset value means that the decrease gradient is below the preset negative value or the decrease gradient. It means that the absolute value of exceeds a preset positive value.

As described above, in this embodiment, when the gas flow rate at which it can be determined that the gas appliance is being used is not measured for a predetermined time, the gas flow passage 11 is temporarily shut off and the gas pressure is monitored. By doing so, it is determined whether or not there is a slight gas leak. Therefore, when it is assumed that a gas leak test can be performed at any time when the gas appliance has not been used for a predetermined time or longer, and a condition where the gas appliance has not been used for a predetermined time or longer exists within 30 days (many This is considered to be the case), and as compared with the conventional function of detecting a small amount of gas leakage, it is possible to detect a small amount of gas leakage earlier and improve safety.

Further, in the present embodiment, when it is determined that a minute amount of gas leakage has not occurred, the gas shutoff valve 12 is automatically opened as soon as the inspection of the minute amount of gas leakage is completed. The gas appliance can be used without bothering the user. In addition, the inspection of a small amount of gas leakage is performed when the gas appliance is not used, and when it is determined that the small amount of gas leakage has not occurred, the gas shutoff valve 12 is automatically operated after the inspection. Since it can be opened, it hardly interferes with the use of gas appliances.

The present invention is not limited to the above embodiment,
For example, in the embodiment, both the decrease amount and the decrease gradient of the gas pressure are calculated, but only one may be calculated to detect a minute amount of gas leakage. Further, in the embodiment, when at least one of the amount of decrease in gas pressure and the decrease gradient exceeds a preset value, it is determined that a slight amount of gas leakage has occurred. It may be determined that a slight amount of gas leakage has occurred when both the amount and the decrease gradient exceed preset values.

The warning method when it is determined that a slight amount of gas leaks is not limited to the lighting of the warning lamp, and other methods such as sounding a buzzer may be used.

[0027]

As described above, according to the gas meter of the first or second aspect, when the gas flow rate at which it can be judged that the gas appliance is used is not measured by the gas flow meter for a predetermined time or more, By gas pressure monitoring means,
For a predetermined period, the gas flow path is shut off, the gas pressure is detected using a gas pressure detection sensor, and fluctuations in the gas pressure are detected.
Since the judging means judges that a slight amount of gas leakage exists when the fluctuation of the gas pressure exceeds a preset value, a minute amount of gas leakage is detected at any time when the gas appliance is not used for a predetermined time or longer. There is an effect that a gas leak inspection can be performed, a minute amount of gas leak can be detected at an early stage, and safety can be improved.

Further, according to the gas meter of the third aspect, when the judging means judges that a small amount of gas leakage is present, the warning means gives a warning. There is an effect that it can be improved.

Further, according to the gas meter of the fourth aspect, the gas shutoff valve control means continues to shut off the gas flow path by the gas shutoff valve control means when the decision means determines that a slight amount of gas leakage exists. , If the judging means does not judge that a slight gas leak exists,
Since the gas shut-off valve control means opens the gas shut-off valve, if it is not determined that a slight gas leak exists, the gas appliance can be used as soon as the gas leak inspection is completed, and each of the above effects can be achieved. In addition, there is an effect that the user's hand is not bothered and the use of the gas appliance is hardly hindered.

[Brief description of drawings]

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

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

3 is a flow chart showing an operation of detecting a small amount of gas leakage in the gas meter of FIG.

FIG. 4 is a characteristic diagram for explaining a method of detecting a small amount of gas leakage in the gas meter of FIG.

[Explanation of symbols]

 10 Gas Meter 11 Gas Flow Path 12 Gas Cutoff Valve 13 Gas Flow Meter 14 Gas Pressure Sensor 15 Control Section 37 Warning Light

Claims (4)

[Claims] 1. A gas passage through which a gas passes, a gas cutoff valve provided in the gas passage for shutting off the gas passage, and provided in the gas passage and passing through the gas passage. A gas flow meter for measuring the flow rate of the gas, a gas pressure detection sensor provided in the gas flow passage for detecting the pressure of the gas in the gas flow passage, and a gas appliance is used for a predetermined time or longer. When the determinable gas flow rate is not measured by the gas flow meter, the gas cutoff valve is driven to cut off the gas flow path for a predetermined period, and the gas pressure is monitored using the gas pressure detection sensor. A gas pressure monitoring unit that detects a variation amount of the gas pressure, and it is determined that a slight amount of gas leakage exists when the variation amount of the gas pressure detected by the gas pressure monitoring unit exceeds a preset value. Equipped with judgment means Gas meter, wherein the door. 2. The gas meter according to claim 1, wherein the gas pressure monitoring unit detects at least one of a decrease amount and a decrease gradient of the gas pressure in the predetermined period as the fluctuation amount of the gas pressure. . 3. The gas meter according to claim 1, further comprising warning means for issuing a warning when the judgment means judges that a slight amount of gas leakage exists. 4. If the determination means determines that a small amount of gas leakage exists, the gas cutoff valve continues to block the gas flow path, and if it is not determined that a small amount of gas leakage exists. The gas meter according to claim 1, further comprising gas cutoff valve control means for opening the gas cutoff valve.