JP3159846B2 - 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 gas leakage.

[0002]

2. Description of the Related Art In recent years, as a household gas meter, a gas meter provided with a safety function in addition to a function of measuring a flow rate of passing gas 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, or when a predetermined gas flow rate is detected for a predetermined time or more, the gas shutoff valve is driven to open the gas flow path. There is a function to shut off. With these functions, leaks in pipes and unnatural gas outflows are detected to prevent accidents before they occur.
It is designed to guarantee safety.

[0003]

However, the above-described conventional function for detecting gas leak has a problem that gas leak less than a set flow rate cannot be detected.

As a function of detecting a small amount of gas leakage, for example, when a situation in which gas has not been used for a predetermined time, for example, one hour cannot be detected for a predetermined number of days, for example, 30 days, a small amount of gas leaks downstream of the gas meter. Although there is a gas meter having a function of determining that a gas leak exists and shutting off the gas, there is a problem that it takes a long time of 30 days to detect a small amount of gas leak.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a gas meter capable of detecting a gas leak at an early stage regardless of the magnitude of the leak amount.

[0006]

The gas meter according to the present invention comprises:
A gas flow path through which gas passes, provided in this gas flow path,
Gas pressure detecting means for detecting the pressure of the gas in the gas flow path, gas flow detecting means for detecting the flow rate of the gas passing through the gas flow path provided in the gas flow path, and being provided in the gas flow path An on-off valve for changing the pressure of gas supplied to the downstream side of the gas meter by changing the flow rate of gas passing therethrough; and driving the on-off valve to actively change the gas pressure, Before and after, respectively, the gas pressure and the gas flow rate are detected using the gas pressure detection means and the gas flow rate detection means, and the presence or absence of gas leakage is determined based on the relationship between the detected gas pressure and the gas flow rate. And a leak detecting means.

In this gas meter, the gas pressure is actively fluctuated by an on-off valve by a gas leak detecting means, and before and after this fluctuation, the gas pressure is detected by a gas pressure detecting means and a gas flow rate detecting means, respectively. And the gas flow rate are detected, and the presence or absence of gas leakage is determined from the relationship between the detected gas pressure and the detected gas flow rate.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 3 relate to one 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, the gas supply system 1 connects a gas meter 10 and a gas appliance 20 by a pipe 17 and supplies gas a. The pipe 17 is provided with a gas stopper 17a.

A gas pipe 11 serving as a gas flow path is disposed inside the gas meter 10. The gas pipe 11 is provided with a gas meter 10 by changing the flow rate of gas passing therethrough.
An on-off valve 12 such as a valve for varying the pressure of the gas supplied to the downstream side of the gas, a gas shutoff valve 13 for shutting off the gas flow path in the event of an abnormality, and detecting the gas pressure in the gas flow path A gas pressure sensor 14 and a gas flow meter 15 for detecting a flow rate of a gas passing through a gas flow path are sequentially arranged.

The gas meter 10 is provided with a control unit 16 for inputting respective outputs of the gas pressure sensor 14 and the gas flow meter 15 and for controlling the on-off valve 12 and the gas cutoff valve 13.

FIG. 2 is a block diagram showing the configuration of the control unit 16 and its periphery in the gas meter 10 of the present embodiment.
As shown in this figure, the control unit 16 includes a CPU (central processing unit) 30, a ROM (read only memory) 31,
RAM (random access memory) 32 and I
It has / O (input / output) ports 33 and 34, which are connected to each other by a bus. The input / output port 33 is connected to the gas pressure sensor 14 and the gas flow meter 15, and the input / output port 34 is connected to the drive circuit 3 for driving the gas shutoff valve 13.
5 and a drive circuit 36 for driving the on-off valve 12 are connected.

In the control unit 16, the CPU 30
By executing a program stored in the ROM 31 using the M32 as a working area, functions such as gas leak detection are realized.

As a function relating to detection of gas leakage, the control section 16 drives the on-off valve 12 to actively change the gas pressure, and before and after this change, respectively.
Gas leak detecting means for detecting the gas pressure and the gas flow rate using the gas pressure sensor 14 and the gas flow meter 15 and determining the presence or absence of a gas leak from the relationship between the detected gas pressure and the gas flow rate. Have.

Next, the operation of the gas meter according to the present embodiment for detecting gas leakage will be described with reference to the flowchart of FIG.

In this operation, first, the control section 16 sets the opening of the on-off valve 12 to the first state by using the drive circuit 36 (step S101). Next, the gas pressure sensor 1
4 to detect the gas supply pressure (step S10).
2) The gas flow rate is detected using the gas flow meter 15 (step S103). The detected gas supply pressure and gas flow rate are stored in the RAM 32 in the control unit 16.

Next, the control section 16 uses the drive circuit 36 to set the opening of the on-off valve 12 to a second state different from the first state (step S104). Thereby, the gap between the valve seats of the on-off valve 12 is changed, the gas flow rate passing through this gap is changed, and the gas supply pressure is changed. Next, similarly to the above, the gas supply pressure is detected using the gas pressure sensor 14 (step S105), and the gas flow meter 1 is detected.
5 is used to detect the gas flow rate (step S106).
The detected gas supply pressure and gas flow rate are stored in the RAM 32 in the control unit 16.

Next, the control unit 16 determines whether the gas supply pressure and the gas flow rate when the opening degree of the on-off valve 12 is in the first state and the opening degree of the on-off valve 12 are stored in the RAM 32 in the second state. The relationship between the gas supply pressure and the gas flow rate is obtained by using the gas supply pressure and the gas flow rate at the time of, and it is necessary to determine the presence or absence of gas leakage from this relationship and to determine the presence or absence of this gas leakage The determination of the gas appliance (determination of the presence or absence of the gas governor) is performed (step S107), and the operation ends.

Here, a method of determining the presence / absence of gas leakage and the method of determining a gas appliance in this embodiment will be described.

When the gas supply pressure is actively changed,
If the gas appliance 20 does not have a function of correcting a change in gas flow rate due to a change in gas supply pressure, the change in gas supply pressure directly causes a change in gas flow rate. In such a case, there is a case where the gas appliance 20 having no gas governor is being used or a gas leak has occurred regardless of the presence or absence of the gas governor. Therefore, when a gas leak occurs, there is a correlation between the gas supply pressure and the gas flow rate.

On the other hand, gas water heaters, bath kettles and the like have a built-in gas governor in the appliance and absorb fluctuations in gas supply pressure with the gas governor.
Even if the gas supply pressure fluctuates, there is no influence on the gas flow rate. Therefore, there is no correlation between the gas supply pressure and the gas flow rate.

Utilizing the above, the determination of the presence or absence of gas leakage and the determination of the gas appliance are performed, for example, as follows.

First, when there is no correlation between the gas supply pressure and the gas flow rate, it is determined that the gas appliance having the gas governor is used or the gas is not used. In the case where the gas leak detection operation is performed when the gas appliance is used, if there is no correlation between the gas supply pressure and the gas flow rate, the gas appliance having the gas governor and the gas leakage do not occur. Is determined.

Next, when there is a correlation between the gas supply pressure and the gas flow rate, it can be seen that a gas leak has occurred in the case of a gas appliance having a gas governor, but a gas appliance having no gas governor has been found. In the case of (1), the presence or absence of gas leakage cannot be determined only by the correlation between the gas supply pressure and the gas flow rate. Therefore, the presence or absence of a gas governor and the presence or absence of a gas leak are determined by adding another condition to the presence or absence of the correlation.

For example, when the ratio of the change in the gas flow rate to the change in the gas supply pressure is equal to or less than a predetermined value, it is determined that a gas leak has occurred. When the operation of detecting gas leakage is performed when the gas appliance is used, it is determined that the gas appliance has a gas governor and that gas leakage has occurred. On the other hand, when the ratio of the change in the gas flow rate to the change in the gas supply pressure exceeds a predetermined value, it is determined that the gas appliance having no gas governor is being used, but it is not known whether there is a gas leak or not. The presence or absence of gas leakage is determined by adding other conditions. For example, after the use of the gas is completed, the correlation between the gas supply pressure and the gas flow rate is checked again, and if there is a correlation, it is determined that a gas leak has occurred. If there is no correlation, no gas leak has occurred. Can be determined.

When the controller 16 determines that a gas leak has occurred, the controller 16 shuts off the gas flow path by the gas shutoff valve 13.

As described above, it is easy to determine the presence or absence of a gas governor and the presence or absence of gas leakage by adding information on whether or not the gas appliance is in use.
Whether or not 0 is in use can be known by detecting ignition using a sensor such as a flame rod, or detecting a sudden increase in gas flow using the gas flow meter 15.

As described above, in the present embodiment, the gas supply pressure is actively changed using the on-off valve 12, and the gas pressure and the gas flow rate before and after this change are detected, and the gas pressure and the gas flow are detected. Since the presence or absence of gas leakage is determined from the relationship with the flow rate, gas leakage can be detected early regardless of the magnitude of the amount of leakage.

In the case where the presence or absence of a gas leak or a gas appliance (the presence or absence of a gas governor) is determined from the relationship between the gas pressure and the gas flow rate, passive household gas caused by the use of gas by surrounding households is used. Although it is conceivable to use pressure fluctuation, it is impossible to predict the pattern of gas pressure fluctuation, the timing of the fluctuation, and the like.

On the other hand, in this embodiment, since the gas supply pressure is actively changed using the on-off valve 12, the pressure can be changed whenever necessary and in an arbitrary change pattern. It is expected that not only the accuracy of gas leak detection and the determination of gas appliances is improved, but also the calculation amount and power consumption are reduced.

The present invention is not limited to the above embodiment,
For example, the on-off valve 12 may serve as the gas shut-off valve 13 without providing the same.

[0032]

As described above, according to the gas meter of the present invention, the gas supply pressure is actively changed using the on-off valve, and the gas pressure and the gas flow rate before and after this change are detected. Since the presence / absence of gas leakage is determined from the relationship between the gas pressure and the gas flow rate, there is an effect that gas leakage can be detected early regardless of the magnitude of the leakage amount.

[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 related to detection of gas leakage in the gas meter of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Gas meter 12 On-off valve 13 Gas shut-off valve 14 Gas pressure sensor 15 Gas flow meter 16 Control part

Claims (1)

(57) [Claims] A gas passage through which a gas passes; a gas pressure detecting means provided in the gas passage for detecting a pressure of the gas in the gas passage; a gas passage provided in the gas passage; Gas flow rate detecting means for detecting the flow rate of gas passing through the flow path; and opening and closing provided in the gas flow path to change the pressure of the gas supplied to the downstream side of the gas meter by changing the flow rate of the passing gas. A valve and the on / off valve are driven to actively change the gas pressure, and before and after this change, the gas pressure and the gas flow rate are detected using the gas pressure detection means and the gas flow rate detection means, respectively. A gas meter comprising: gas leak detecting means for judging the presence or absence of a gas leak from the relationship between the detected gas pressure and the detected gas flow rate.