JPH0777448A - Gas meter - Google Patents

Abstract

PURPOSE:To provide a gas meter capable of finding a slight gas leakage at an early stage and giving no trouble to the use of a gas appliance. CONSTITUTION:A controller 15 temporarily cuts off a gas passage 11 with a gas shut-off valve 12 when a gas flow to be judged for the use of a gas utensil is not measured by a gas flow meter 13 for a prescribed period or longer and inspects the presence or absence of a slight gas leakage based on the gas flow measured by the gas flowmeter 13. When the controller 15 detects an abrupt increase of the gas flow during the inspection, it judges that a gas appliance is used, and it interrupts the inspection and opens the gas shut-off valve 12.

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.

Therefore, the applicant of the present invention temporarily shuts off the gas flow path and measures the gas flow rate by a gas flow meter when the gas flow rate at which it can be determined that the gas appliance is used is not measured for a predetermined time or longer. It proposes a technique for inspecting the presence or absence of a small amount of gas leakage based on the gas flow rate.

According to this technique, it is possible to detect a small amount of gas leakage earlier than in the prior art, but a gas appliance is used because the gas flow path is blocked during the inspection of the small amount of gas leakage. There was a problem that it could not be done, and there was room for improvement.

The present invention has been made in view of the above problems, and an object thereof is to make it possible to detect a small amount of gas leakage at an early stage and not to hinder the use of a gas appliance. It is to provide a gas meter.

[0008]

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 that is installed in the passage and that measures the flow rate of the gas that passes through this gas flow path, and if the gas flow rate that can be judged that the gas appliance is used for a predetermined time or more is not measured by the gas flow meter. A minute gas leakage inspection means for inspecting the presence or absence of a minute amount of gas leakage based on the flow rate of the gas measured by the gas flow meter by driving the gas cutoff valve to shut off the gas flow path; and this minute gas leakage inspection means During the inspection by the gas flow meter, the flow rate increase detection means for detecting a rapid increase in the flow rate of the gas measured by the gas flow meter, and when the rapid increase in the flow rate of the gas is detected by the flow rate increase detection means, the gas appliance is use It is determined to have been, suspended inspection by trace gas leak test means, but with a test interruption means Toto opening the gas shut-off valve.

In this gas meter, when the gas flow rate at which the gas flow rate can be judged to be using the gas appliance is not measured by the gas flow meter for a predetermined period of time or longer, the gas flow path is blocked by the trace gas leakage inspection means, The presence or absence of a slight gas leak is inspected based on the flow rate of the gas measured by the flow meter. Further, during this inspection, when a rapid increase in the flow rate of gas is detected by the flow rate increase detection means, it is determined that the gas appliance is used by the inspection interruption means,
The inspection by the trace gas leak inspection means is interrupted and the gas cutoff valve is opened.

A gas meter according to a second aspect is the gas meter according to the first aspect, wherein the flow rate increase detecting means integrates the flow rate of the gas measured by the gas flow meter, and the gas integrated by the integrating means. And an deciding means for deciding that the flow rate of the gas has rapidly increased when the increasing gradient obtained by the calculating means exceeds a predetermined range. .

In this gas meter, by the integrating means,
The flow rate of the gas is integrated, the increasing gradient of the integrated flow rate of the gas is calculated by the calculating means, and when the increasing gradient exceeds a predetermined range, the determining means determines that the gas flow rate is rapidly increased. To be done.

A gas meter according to a third aspect of the present invention is the gas meter according to the first or second aspect, in which the trace gas leak inspection means integrates the flow rate of the gas measured by the gas flow meter, and the integrated flow rate is preset. When the value exceeds the specified value, it is judged that a slight gas leak exists.

A gas meter according to a fourth aspect is the gas meter according to the first or second aspect, in which the trace gas leak inspection means measures the gas flow rate per unit time by using a gas flow meter and When the gas flow rate exceeds a preset value, it is determined that there is a slight gas leak.

[0014]

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 configuration 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.

Further, in the gas meter 10, there is provided a control section 15 for inputting the respective outputs of the gas flow meter 13 and the gas pressure detecting sensor 14 and controlling the gas cutoff valve 12 and the like.

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 an inspection for a small amount of gas leakage is realized.

The control unit 15 has a function relating to the inspection of a small amount of gas leakage, in particular, 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 13 for a predetermined time or longer, the gas shutoff is performed. A trace gas leak inspection means for inspecting the presence or absence of a trace gas leak based on the gas flow rate measured by the gas flow meter 13 by driving the valve 12 to shut off the gas flow path 11, and this trace gas leak inspection means. During the inspection by the gas flow meter 13, a flow rate increase detecting means for detecting a rapid increase in the flow rate of the gas measured by the gas flow meter 13 and a gas appliance when the rapid increase in the flow rate of the gas is detected by the flow rate increase detecting means. Was judged to have been used,
Each function of the inspection interruption means for interrupting the inspection by the trace gas leak inspection means and opening the gas cutoff valve 12 is provided. The flow rate increase detecting means is obtained by integrating means for integrating the flow rate of gas measured by the gas flow meter 13, calculating means for calculating the increasing gradient of the flow rate of gas integrated by the integrating means, and this calculating means. And a determination means for determining that the flow rate of the gas sharply increases when the increasing gradient exceeds a predetermined range.

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 inspecting the presence or absence of a small amount of gas leakage as described below.

FIG. 3 is a flow chart showing the operation of inspecting for the presence or absence of a slight gas leak. In this operation, first, the control unit 1
5, it is determined whether to start the trace gas leak inspection mode (step S101). Specifically, a state in which it can be determined that the gas appliance is unused, that is, a state in which the gas flow rate that can be determined that the user is using the gas appliance in the normal usage state is not measured by the gas flow meter 13 continues for a predetermined time. If so, the trace gas leak inspection mode is started. When the trace gas leak inspection mode is not started (N), the above determination (step S101) is repeated.

When the trace gas leak inspection mode is started (step S101; Y), the gas shutoff valve 12 is driven through the drive circuit 36 to shut off the gas flow path 11, and the gas flow meter 13 is used to turn off the gas. The monitoring of the flow rate is started (step S102). The flow rate measured by the gas flow meter 13 is sequentially stored in the RAM 32 in the control unit 15. Next, the control unit 15 determines whether or not a predetermined time required for the trace gas leak inspection has elapsed (step S103). If it has not elapsed (N), the flow rate of the gas measured by the gas flow meter 13 is integrated (step S104), and then the increasing gradient of this integrated flow rate is calculated (step S10).
5) Then, it is determined whether or not this increasing gradient is within a predetermined range (step S106). If the increasing gradient is within the predetermined range (Y), the process returns to step S103. on the other hand,
If the increase gradient is not within the predetermined range (N), it is determined that the gas appliance is used, the trace gas leak inspection mode is interrupted, the gas shutoff valve 12 is opened (step S107),
The operation ends. This allows the use of gas appliances.

When the predetermined time required for the trace gas leak inspection has passed without interruption of the trace gas leak inspection mode (step S103; Y), the inspection result is processed (step S108), and the operation is performed. To finish. The processing of the inspection result is specifically performed as follows. That is, the flow rate of the gas measured by the gas flow meter 13 is integrated within a predetermined time required for the trace gas leak inspection, and it is determined whether or not the integrated flow rate exceeds a preset value. To determine if there is a gas leak in. Alternatively, determine the gas flow rate per unit time,
By determining whether or not the flow rate of gas per unit time exceeds a preset value, it is determined whether or not there is a slight gas leak. When there is a slight gas leak, the control unit 15 continues to shut off the gas flow path 11 by the gas shutoff valve 12, outputs a warning signal and turns on the warning lamp 37, and ends the operation. When a slight amount of gas leakage does not exist, the control unit 15 returns or opens the gas cutoff valve 12 and ends the operation.

FIG. 4 is a characteristic diagram for explaining a method for inspecting a small amount of gas leakage and a method for judging interruption of the inspection in this embodiment, and the horizontal axis shuts off the gas flow passage 11 by the gas shutoff valve 12. The elapsed time since then, the vertical axis represents the cumulative gas flow rate. 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, the gas flow rate is detected to some extent even if the gas flow path 11 is shut off, and the gas flow path is detected. It is known that the integrated flow rate increases as the elapsed time from shutting off 11 increases. Therefore, in the present embodiment, the gas flow rate is monitored within a predetermined period after the gas flow path 11 is shut off, and a small amount of gas leakage occurs when the integrated flow rate of the gas during this predetermined period exceeds a preset value. Is determined to exist. Alternatively, when the gas flow rate per unit time exceeds a preset value, it is determined that there is a slight gas leak. It is also possible to estimate the size of the hole from the increasing gradient of the integrated gas flow rate or the size of the gas flow rate per unit time. If the integrated value of the gas flow rate exceeds a preset value before the expiration of the predetermined period, it may be determined that a slight amount of gas leakage exists at that time.

If the user starts to use the gas appliance during the inspection for such a slight gas leak, the gas pressure may drop and the gas appliance may become unusable. Therefore, in this embodiment, during the inspection of a slight amount of gas leakage,
Obtain the increasing slope of the cumulative gas flow rate, and if this increasing slope exceeds a predetermined range, that is, if the gas flow rate increases rapidly, determine that the user has started using the gas appliance and promptly The inspection is interrupted and the gas cutoff valve 12 is opened. In the example of FIG. 4, the inspection is interrupted at the time indicated by the symbol a and the gas cutoff valve 12 is opened. In addition,
In FIG. 4, the curve after the time point a is the gas cutoff valve 12
It shows the change in the integrated flow rate when the valve is not opened.

As described above, in the present 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 path 11 is temporarily shut off and the gas flow rate 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 small amount of gas leakage has not occurred, the gas shutoff valve 12 is automatically opened as soon as the inspection of the small amount of gas leakage is completed. The gas appliance can be used without bothering the user.

Further, in the present embodiment, 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 does not occur, the inspection is automatically performed after the inspection is completed. Since the gas shutoff valve 12 is opened, and the gas shutoff valve 12 is opened promptly even when the use of the gas appliance is started during the inspection, the use of the gas appliance is not hindered.

The present invention is not limited to the above embodiment,
For example, as a method of detecting a rapid increase in gas flow rate, the rate of change in gas flow rate per unit time is obtained, and when this rate of change exceeds a predetermined value, it is determined that the gas flow rate has increased rapidly. It may be done.

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

[0032]

As described above, according to the gas meter of the first to fourth aspects, 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 longer, The gas flow path was blocked by the trace gas leak inspection means, and the presence or absence of trace gas leaks was checked based on the flow rate of the gas measured by the gas flow meter. There is an effect that a test for a small amount of gas leakage can be performed at any time when it is not present, a small amount of gas leakage can be detected early, and safety can be improved. Further, during the inspection, when a rapid increase in the flow rate of the gas is detected by the flow rate increase detection means, the inspection interruption means judges that the gas appliance is used, interrupts the inspection, and opens the gas cutoff valve. Therefore, there is an effect that it does not hinder the use of the gas appliance.

[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.

FIG. 3 is a flowchart showing an operation of inspecting the gas meter of FIG. 1 for the presence or absence of a slight gas leak.

FIG. 4 is a characteristic diagram for explaining a method of inspecting a slight amount of gas leakage and a method of determining interruption of inspection in the gas meter of FIG.

[Explanation of symbols]

 10 gas meter 11 gas flow path 12 gas cutoff valve 13 gas flow meter 15 controller

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 that measures the flow rate of the gas and a gas flow meter that drives the gas shutoff valve when the gas flow rate at which the gas appliance can be judged to be in use for a predetermined period of time is not measured by the gas flow meter. A trace gas leak inspecting means for inspecting the presence or absence of a trace gas leak based on the flow rate of the gas measured by the gas flow meter, and a gas flow meter during the inspection by the trace gas leak inspecting means. Flow rate increase detection means for detecting a rapid increase in the flow rate of gas measured by, and when a rapid increase in the flow rate of gas is detected by this flow rate increase detection means, it is determined that the gas appliance is used, Previous Interrupted inspection by trace gas leak test means, characterized by comprising an inspection interruption means for opening the gas shut-off valve the gas meter. 2. The flow rate increase detecting means includes an integrating means for integrating the gas flow rates measured by the gas flow meter, and an operating means for calculating an increasing gradient of the gas flow rate integrated by the integrating means. The gas meter according to claim 1, further comprising: a determining unit that determines that the flow rate of the gas has rapidly increased when the increase gradient obtained by the calculating unit exceeds a predetermined range. 3. The trace gas leak inspection means integrates the flow rates of the gas measured by the gas flow meter, and when the integrated flow rate exceeds a preset value, a trace gas leak exists. The gas meter according to claim 1 or 2, wherein the gas meter is determined. 4. The trace gas leakage inspection means measures the flow rate of gas per unit time using the gas flow meter,
The gas meter according to claim 1 or 2, wherein it is determined that a slight amount of gas leakage exists when the gas flow rate per unit time exceeds a preset value.