JPH0777446A - Gas meter - Google Patents

Abstract

PURPOSE:To detect gas leakage at an early stage regardless of the magnitude of a leak quantity by driving an opening/closing valve to actively change the gas pressure, and detecting the pressure and flow of gas before and after the change. CONSTITUTION:A controller 16 sets the opening of an opening/closing valve 12 to the first state with a drive circuit, detects the gas feed pressure with a gas pressure sensor 14, and detects the gas flow with a gas flowmeter 15. The detected gas feed pressure and gas flow are stored in the RAM of a controller 16. The controller 16 sets the opening of the opening/closing valve 12 to the second state. The gap of the valve seat of the opening/closing valve 12 is changed, and the gas feed pressure is changed. The gas feed pressure and the gas flow are detected by the sensor 14 and the flowmeter 15, and they are stored in the RAM. The controller 16 obtains the relationship between the gas feed pressures and the gas flows stored in the RAM when the opening of the opening/closing valve 12 is set to the first and second states, and it judges the presence or absence of a gas leakage and judges the quality of a gas appliance.

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 gas leakage.

[0002]

2. Description of the Related Art In recent years, as a household gas meter, one having 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 drive the gas shutoff valve to open the gas flow path when a flow rate meter detects a gas flow rate higher than a predetermined amount, or when a predetermined gas flow rate is detected for a predetermined time or longer. There is a function to shut off. With these functions, leaks in piping and outflow of unnatural gas can be detected to prevent accidents.
It is designed to guarantee safety.

[0003]

However, there is a problem that the conventional gas leak detecting function as described above cannot detect a gas leak below the set flow rate.

Further, as a function of detecting a slight amount of gas leakage, for example, when a situation in which 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 is provided downstream of the gas meter. There is a gas meter having a function of interrupting the gas by judging that there is a gas leak, but there is a problem that it takes a long period of 30 days to detect a minute amount of gas leak.

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

[0006]

The gas meter of the present invention comprises:
A gas passage through which a gas passes, and provided in this gas passage,
Gas pressure detecting means for detecting the pressure of the gas in the gas flow path, a gas flow rate detecting means provided in the gas flow path, for detecting the flow rate of the gas passing through the gas flow path, and provided in the gas flow path , An on-off valve for changing the pressure of the gas supplied to the downstream side of the gas meter by changing the flow rate of the passing gas, and driving the on-off valve to actively change the gas pressure and A gas that detects the gas pressure and the gas flow rate using the gas pressure detection means and the gas flow rate detection means, respectively, and determines the presence or absence of gas leakage from the relationship between the detected gas pressure and the gas flow rate. And a leak detecting means.

In this gas meter, the gas leak detection means actively changes the gas pressure using the on-off valve, and the gas pressure detection means and the gas flow rate detection means are used before and after the change, respectively. And the flow rate of the gas is detected, and the presence or absence of gas leakage is determined from the relationship between the detected gas pressure and the gas flow rate.

[0008]

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

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

A control unit 16 is provided in the gas meter 10 for inputting the outputs of the gas pressure sensor 14 and the gas flow meter 15 and 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 peripherals in the gas meter 10 of this 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
/ O (input / output) ports 33 and 34 are connected to each other by a bus. A gas pressure sensor 14 and a gas flow meter 15 are connected to the input / output port 33, and a drive circuit 3 for driving the gas cutoff valve 13 is connected to the input / output port 34.
5 and a drive circuit 36 for driving the on-off valve 12 are connected.

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

As a function relating to gas leak detection, the control unit 16 drives the on-off valve 12 to actively fluctuate the gas pressure, and before and after this fluctuation, respectively.
The gas pressure sensor 14 and the gas flow meter 15 are used to detect the gas pressure and the gas flow rate, and gas leak detection means for determining the presence or absence of gas leakage from the relationship between the detected gas pressure and the gas flow rate is provided. Have

Next, the operation relating to the detection of gas leakage in the gas meter of this embodiment will be described with reference to the flow chart of FIG.

In this operation, first, the control unit 16 sets the opening degree 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 is used 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 unit 16 uses the drive circuit 36 to set the opening degree of the on-off valve 12 to a second state different from the first state (step S104). As a result, the gap of the valve seat 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, in the same manner as above, the gas supply pressure is detected using the gas pressure sensor 14 (step S105), and the gas flow meter 1
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 controller 16 stores the gas supply pressure and the gas flow rate stored in the RAM 32 when the opening / closing valve 12 is in the first state and the opening / closing valve 12 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, and it is necessary for determining the presence or absence of gas leakage from this relationship and for determining the presence or absence of this gas leakage. The gas appliance is determined (determination of the presence or absence of the gas governor) (step S107), and the operation ends.

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

When the gas supply pressure is actively changed,
If the gas appliance 20 side does not have the function of correcting the change in gas flow rate due to the change in gas supply pressure, the change in gas supply pressure causes the change in gas flow rate as it is. In such a case, a gas leak may occur during use of the gas appliance 20 having no gas governor or 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, a gas water heater, a bath kettle, etc., has a gas governor built in the equipment, and since the gas governor absorbs the fluctuation of the gas supply pressure, if no gas leakage occurs,
Even if the gas supply pressure fluctuates, it does not affect the gas flow rate. Therefore, there is no correlation between the gas supply pressure and the gas flow rate.

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

First, if 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. If the gas leak detection operation is performed when the gas appliance is used, unless there is a correlation between the gas supply pressure and the gas flow rate, it is a gas appliance having a gas governor, and no gas leak has occurred. 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 occurs in the case of a gas appliance having a gas governor, but a gas appliance having no gas governor. 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 the gas governor and the presence or absence of the gas leak are determined by adding other conditions to the presence or absence of the correlation.

For example, when the ratio of the fluctuation of the gas flow rate to the fluctuation of the gas supply pressure is less than or equal to a predetermined value, it is determined that the gas leakage has occurred. When the gas leak detection operation is performed when the gas appliance is used, it is determined that the gas appliance has a gas governor and that a gas leak has occurred. On the other hand, if the rate of fluctuation of the gas flow rate with respect to the fluctuation of the gas supply pressure exceeds a predetermined value, it is determined that a gas appliance without a gas governor is in use, but it is unknown whether or not there is a gas leak. The presence or absence of gas leakage is determined by adding other conditions. For example, after the use of 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 it is determined that the gas leakage has occurred, the control unit 16 shuts off the gas flow path by the gas shutoff valve 13.

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

As described above, in this embodiment, the gas supply pressure is actively changed by using the on-off valve 12, and the gas pressure and the gas flow rate before and after this change are detected to detect the gas pressure and the gas pressure. 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 amount of leakage.

When determining the presence or absence of a gas leak or the gas appliance (presence or absence of a gas governor) from the relationship between the pressure of the gas and the flow rate of the gas, a passive gas caused by the surrounding households using the gas Although it is possible to use the pressure fluctuation, it is impossible to predict the gas pressure fluctuation pattern, the fluctuation timing, and the like.

On the other hand, in this embodiment, since the gas supply pressure is actively changed by using the opening / closing valve 12, it is possible to cause the pressure change whenever necessary and in any change pattern. In addition to improving the accuracy of gas leak determination and gas appliance determination, it is expected that the calculation amount will be reduced and the power consumption will be reduced.

The present invention is not limited to the above embodiment,
For example, the opening / closing valve 12 may double as this without providing the gas cutoff valve 13.

[0032]

As described above, according to the gas meter of the present invention, the on / off valve is used to actively fluctuate the gas supply pressure, and the gas pressure and the gas flow rate before and after this fluctuation are detected, Since the presence / absence of gas leakage is determined based on the relationship between the gas pressure and the gas flow rate, the gas leakage can be detected early regardless of the amount of leakage.

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

[Explanation of symbols]

 10 gas meter 12 on-off valve 13 gas shutoff valve 14 gas pressure sensor 15 gas flow meter 16 controller

Claims (1)

[Claims] 1. A gas passage through which a gas passes, gas pressure detection means provided in the gas passage to detect the pressure of the gas in the gas passage, and the 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 / closing for varying the pressure of gas supplied to the downstream side of the gas meter by changing the flow rate of gas passing through the gas flow path. The valve and the on-off valve are driven to actively fluctuate the gas pressure, and the gas pressure and the gas flow rate are detected before and after the fluctuation by using the gas pressure detection means and the gas flow rate detection means, respectively. And a gas leak detecting means for determining the presence or absence of a gas leak from the relationship between the detected gas pressure and the gas flow rate.