JP3137512B2 - Gas meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In recent years, as a household gas meter, in addition to a function of measuring a flow rate of gas passing therethrough, a gas meter equipped with a microcomputer and added with a safety function has been put into practical use. As a safety function of this gas meter, when a gas flow rate of a predetermined amount or more is detected using a flow meter, when a predetermined gas flow rate is detected for a predetermined time or more, or when a gas pressure detection sensor is used to supply a gas at a predetermined pressure or more. When there is no pressure, there is a function of driving a gas shutoff valve to shut off a gas flow path. With these functions, leaks in pipes and unnatural gas outflows are detected to prevent accidents before they occur.
It is designed to guarantee safety.

As a safety function of a gas meter equipped with a microcomputer, there is also a function of detecting a small amount of gas leakage in addition to the function described above. The function of detecting a small amount of gas leakage in a conventional gas meter is, for example, a case where no gas has been used for a predetermined time, for example, one hour or more, for a predetermined number of days, for example, 30 days. The gas was determined to be present and the gas was shut off.

[0004]

However, with the above-described conventional function for detecting a small amount of gas leakage, it takes a long time of 30 days to detect the small amount of gas leakage, and the small amount of gas leakage is detected. Cannot be detected early.

[0005] 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 a small amount of gas leakage at an early stage.

[0006]

According to a first aspect of the present invention, there is provided a gas meter, comprising: a gas passage through which a gas passes; a gas shut-off valve provided in the gas passage to shut off the gas passage; A gas flow meter that is provided in the passage and measures the flow rate of the gas passing through the gas flow path; a gas pressure detection sensor that is provided in the gas flow path and detects the pressure of the gas in the gas flow path; As described above, when the gas flow rate that can be determined to be using the gas appliance is not measured by the gas flow meter, the gas cutoff valve is driven to shut off the gas flow path for a predetermined period, and the gas pressure detection sensor is used. Gas pressure monitoring means for monitoring the gas pressure to detect the amount of change in the gas pressure; and, if the amount of change in the gas pressure detected by the gas pressure monitoring means exceeds a predetermined value, a very small amount. Determine that there is a gas leak It is obtained by a cross section.

In this gas meter, when a gas flow rate that can be determined to be using the gas appliance is not measured by the gas flow meter for a predetermined time or more, the gas flow path is shut off by the gas pressure monitoring means for a predetermined period. The pressure of the gas is monitored using a gas pressure detection sensor, and the fluctuation amount of the gas pressure is detected. Then, when the fluctuation amount of the gas pressure detected by the gas pressure monitoring means exceeds a preset value, the determination means determines that a small amount of gas leakage exists.

According to a second aspect of the present invention, in the gas meter according to the first aspect, 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 the change amount of the gas pressure. It is something to do.

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 a warning unit for issuing a warning when the determination unit determines that a small amount of gas leakage exists.

In this gas meter, a warning is issued by the warning means when the determination means determines that a small amount of gas leakage exists.

[0011] The gas meter according to claim 4 is characterized in that:
In the gas meter described in 2 or 3, when the determination means determines that a small amount of gas leakage is present, the gas shutoff valve continues to shut off the gas flow path, and it is not determined that the small amount of gas leakage exists. In this case, a gas shutoff valve control means for opening the gas shutoff valve is provided.

In this gas meter, when the judgment means judges that a small amount of gas leakage exists, the gas cut-off valve control means keeps shutting off the gas flow path by the gas cut-off valve, and the judgment means judges that the gas leakage is small. Is not determined to exist, the gas shut-off valve is opened by the gas shut-off valve control means. Accordingly, when it is not determined that a small amount of gas leakage exists, the gas appliance can be used as soon as the gas leakage inspection is completed.

[0013]

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

FIG. 1 is an explanatory diagram showing a schematic configuration of a gas meter according to the present embodiment. As shown in this figure, a gas flow path 11 having a gas inlet 16 and a gas outlet 17 is provided inside the gas meter 10 of the present embodiment. A gas 20 flows into the gas passage 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 paths 1
1, a gas flow meter 13 for measuring the flow rate of gas passing through the gas flow path 11, and a gas pressure detection sensor 14 for detecting the pressure of gas in the gas flow path 11. Are arranged.

The gas meter 10 is provided with a control unit 15 for inputting each output of the gas flow meter 13 and the gas pressure detection sensor 14 and controlling the gas shutoff valve 12 and the like.

FIG. 2 is a block diagram showing the configuration of the control unit 15 and its periphery in the gas meter 10 of the present 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 measuring time, and an input / output port 34 are connected to each other by a bus 35.
The input / output port 34 is connected to a drive circuit 36 for driving the gas shut-off valve 12 and a warning lamp 37 for warning the occurrence of a small amount of gas leakage, in addition to the gas flow meter 13 and the gas pressure detection sensor 14 described above. Have been.

In the control unit 15, the CPU 30
By executing a program stored in the ROM 31 using the M32 as a working area, a safety function such as detection of a small amount of gas leakage is realized.

The control unit 15 has a function for detecting a small amount of gas leakage, in particular, when a gas flow rate at which it is determined that the gas appliance is being used has not been measured by the gas flow meter 13 for a predetermined time or more, a predetermined period of time. , The gas cutoff valve 12 is driven to shut off the gas flow path 11 and the gas pressure detection sensor 1
4, a gas pressure monitoring means for monitoring the gas pressure to detect a variation in the gas pressure, and the variation in the gas pressure detected by the gas pressure monitoring means exceeds a preset value. In this case, a determining means for determining that a small amount of gas leakage exists, a warning means for turning on a warning lamp 37 to issue a warning when the determining means determines that a small amount of gas leakage exists, If it is determined that a gas leak exists, the gas shut-off valve 12 continues to shut off the gas flow path 11, and if it is not determined that a small amount of gas leaks, the gas shut-off valve 12 is opened. It has each function of the means.

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

The gas meter of the present embodiment has a gas flow meter 13
The flow rate of the gas passing through the gas flow path 11 is measured by the
The pressure of the gas inside is detected. And
As in the conventional case, when a gas flow rate of a predetermined amount or more is detected using the gas flow meter 13, when a predetermined gas flow rate is detected for a predetermined time or more, or when a gas pressure detection sensor 14 is used to supply gas at a predetermined pressure or higher. 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 or the like. The gas meter of the present embodiment has a function of detecting a small amount of gas leakage as described below, in addition to these safety functions.

FIG. 3 is a flowchart showing the operation of detecting a small amount of gas leakage. In this operation, first, the gas flow meter 13 measures a state in which the control unit 15 can determine that the gas appliance is unused, that is, a gas flow rate that can determine that the user is using the gas appliance in a normal use state. It is determined whether or not the state of not being performed has continued for a predetermined time (step S101). If it does not continue for the predetermined time (N), the above determination (step S101) is repeated. If the predetermined time has elapsed (Y), the gas cutoff valve 12 is driven via the drive circuit 36 to cut off the gas flow path 11 for a predetermined time, and during that time, the gas pressure is detected using the gas pressure detection sensor 14. Monitoring is performed (step S102). The pressure detected by the gas pressure detection sensor 14 at each point in the predetermined period is stored in the RAM 32 in the control unit 15. Next, the control unit 15
Calculates the amount of change in the gas pressure during the predetermined period and the decrease amount and the gradient of the gas pressure from the pressure at each point in the predetermined period (step S103). Next, the control unit 15 determines whether or not a small amount of gas leakage exists by determining whether at least one of the amount of decrease in the gas pressure and the decrease gradient exceeds a predetermined value ( Step S104). If there is a small amount of gas leakage (Y), the control unit 15 continues to shut off the gas flow path 11 by the gas shut-off valve 12, emits a warning signal, and turns on the warning lamp 37 (step S105). , End the operation. If there is no minute gas leak (step S1
04; N), the control unit 15 returns or opens the gas shutoff valve 12 (Step S106), and ends the operation.

FIG. 4 is a characteristic diagram for explaining a method for detecting a small amount of gas leakage from the amount and the gradient of decrease in gas pressure. The horizontal axis indicates that the gas passage 11 is shut off by the gas shut-off valve 12. The vertical axis indicates the pressure of the gas. As shown in this figure, when a small amount of gas leaks due to a hole in a pipe downstream of the gas meter 10 or the like, the pressure of the gas increases as the elapsed time after the gas flow path 11 is shut off increases. It has been found to decrease. Therefore, in this embodiment, the pressure of the gas is monitored within a predetermined period indicated by reference character a in FIG. 4, and the amount of decrease and the gradient of the gas pressure during the predetermined period a are calculated. If at least one of the pressure gradient and the decreasing gradient exceeds a preset value, it is determined that a small amount of gas leakage exists. It is also possible to estimate the size of the hole from the magnitude of the pressure drop gradient. In addition, since the decreasing gradient of the gas pressure is a negative value, the fact that the decreasing gradient of the gas pressure exceeds the preset value means that the decreasing gradient is lower than the preset negative value or the decreasing gradient is lower than the preset value. Is greater than a preset positive value.

As described above, in this embodiment, when a state in which the gas flow rate at which the gas appliance can be determined to be used is not measured continues for a predetermined time, the gas flow path 11 is once shut off and the gas pressure is monitored. Thus, it is determined whether or not a small amount of gas leakage exists. Therefore, a small amount of gas leak inspection can be performed at any time when the gas appliance is not used for a predetermined time or more, and it is assumed that a state where the gas appliance is not used for a predetermined time exists within 30 days (many cases). In such a case, it is possible to detect a small amount of gas leakage earlier than in the conventional function of detecting a small amount of gas leakage, thereby improving safety.

In this embodiment, when it is determined that a small amount of gas leakage has not occurred, the gas shut-off 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. In addition, the inspection for 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 shut-off valve 12 Since it can be opened, it hardly hinders 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 of them may be calculated to detect a small amount of gas leakage. Further, in the embodiment, when at least one of the decrease amount and the decrease gradient of the gas pressure exceeds a predetermined value, it is determined that a small amount of gas leakage has occurred. When both the amount and the decrease gradient exceed a preset value, it may be determined that a small amount of gas leakage has occurred.

The method of warning when it is determined that a small amount of gas leakage is present is not limited to the turning on of the warning lamp, and other methods such as sounding a buzzer may be used.

[0027]

As described above, according to the gas meter according to the first or second aspect, when the gas flow rate that can be determined to be using the gas appliance for a predetermined time or more is not measured by the gas flow meter, By gas pressure monitoring means,
For a predetermined period, shut off the gas flow path, monitor the gas pressure using a gas pressure detection sensor to detect a change in the gas pressure,
By the determining means, when the fluctuation of the gas pressure exceeds a preset value, it is determined that there is a small amount of gas leakage, so when the gas appliance is not used for a predetermined time or more, a small amount Inspection of gas leakage can be performed, a small amount of gas leakage can be found at an early stage, and there is an effect that safety can be improved.

Further, according to the gas meter of the present invention, a warning is issued by the warning means when it is determined by the determination means that a small amount of gas leaks. There is an effect that it can be improved.

According to the gas meter of the present invention, when the judgment means judges that a small amount of gas leaks, the gas cutoff valve control means keeps shutting off the gas flow path by the gas cutoff valve. If the determination means does not determine that a small amount of gas leakage exists,
Since the gas shut-off valve is opened by the gas shut-off valve control means, if it is not determined that there is a small amount of gas leak, the gas appliance can be used as soon as the gas leak inspection is completed. 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 the drawings]

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

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

FIG. 3 is a flowchart 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]

 DESCRIPTION OF SYMBOLS 10 Gas meter 11 Gas flow path 12 Gas shutoff valve 13 Gas flow meter 14 Gas pressure sensor 15 Control part 37 Warning light

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-209769 (JP, A) JP-A 4-117970 (JP, U) JP-A 4-102022 (JP, U) (58) Investigation Field (Int.Cl. ⁷ , DB name) G01F 3/22 G01F 1/00

Claims (4)

(57) [Claims] A gas passage through which a gas passes; a gas shutoff valve provided in the gas passage for shutting off the gas passage; and a gas shutoff valve provided in the gas passage and passing through the gas passage. A gas flow meter for measuring a flow rate of a gas to be supplied; a gas pressure detection sensor provided in the gas flow path, for detecting a pressure of the gas in the gas flow path; When the gas flow rate that can be determined is not measured by the gas flow meter, for a predetermined period, the gas shutoff valve is driven to shut off the gas flow path, and the gas pressure is monitored using the gas pressure detection sensor. Gas pressure monitoring means for detecting the amount of change in gas pressure; and determining that a small amount of gas leakage exists when the amount of change in gas pressure detected by the gas pressure monitoring means exceeds a preset value. With judgment means Gas meter, wherein the door. 2. The gas meter according to claim 1, wherein the gas pressure monitoring means detects at least one of a decrease amount and a decrease gradient of the gas pressure in the predetermined period as the amount of change in the gas pressure. . 3. The gas meter according to claim 1, further comprising a warning unit that issues a warning when the determination unit determines that a small amount of gas leakage exists. 4. When the determination means determines that a small amount of gas leakage is present, the gas cutoff valve continues to shut off the gas flow path, and when it is not determined that a small amount of gas leakage is present, 4. The gas meter according to claim 1, further comprising gas shutoff valve control means for opening the gas shutoff valve.