JP2995419B2 - Automatic gas shut-off device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an automatic gas shutoff device that detects a gas leak from a gas flow passage and shuts off a shutoff valve.

<Prior Art> A conventional automatic gas shut-off device shuts off a gas flow when a gas leak detector detects a flammable gas.

Then, in order to prevent the gas leak detector from malfunctioning in response to miscellaneous gas, for example, LP gas in insecticide or alcohol in breath, it is determined whether or not gas is used, and the gas is not used. An automatic gas leak shut-off device which is configured not to judge a gas leak even if a gas leak detector reacts in such a case is disclosed in JP-A-63-296198 filed by the present applicant.

<Problems to be Solved by the Invention> However, the above-described conventional gas leak automatic shut-off device can prevent malfunction due to miscellaneous gas when not using gas, but uses gas. In such a case, it is impossible to distinguish between a true gas leak and an effect of miscellaneous gas, and thus a malfunction may occur.

<Means for Solving the Problems> The present invention has been proposed in view of the above, and can prevent malfunction due to the influence of miscellaneous gas. A shutoff valve for shutting off a gas flow, a flow sensor for detecting a gas flow flowing in a gas flow path, a flow signal transmitter for transmitting a flow signal when the flow sensor detects a gas flow, A gas leak detector for detecting gas and transmitting a gas detection signal; first gas leak determination means for determining the possibility of gas leakage based on the flow signal and the gas detection signal; A first monitoring unit for monitoring, a second monitoring unit for monitoring an output variation of the flow signal, and a first monitoring unit and a second monitoring unit when the first gas leakage determination unit determines that there is a possibility of gas leakage. Gas leaks based on monitoring results A second gas leak determining means for determining whether or not gas is leaking; and a shutoff signal for transmitting a shutoff signal for operating a shutoff valve when the second gas leak determining means determines that gas is leaking. Signal transmitting means.

<Operation> When the flow sensor that monitors the gas flow in the gas flow path detects the gas flow, the flow signal transmitter transmits a flow signal.

The gas leak detector monitors the combustible gas, and when detecting the combustible gas, emits a gas detection signal.

The first monitoring means monitors the output fluctuation of the gas detection signal, and the second monitoring means monitors the output fluctuation of the flow rate signal.

The first gas leak determining means performs an operation based on the flow signal and the gas detection signal to determine whether there is a possibility of gas leak.

If the first gas leak determining means determines that there is a possibility of gas leak, the second gas leak determining means performs an operation based on the monitoring results of the first monitoring means and the second monitoring means, It is determined whether the detection of gas or the detection of gas by miscellaneous gas.

When the second gas leak determination unit determines that the gas is detected due to the gas leakage, the shutoff signal transmitting unit transmits a shutoff signal to the shutoff valve to shut off the gas flow in the gas flow path.

<Example> Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic block diagram of an automatic gas shut-off device 1 according to the present invention.

This gas automatic shutoff device 1 is provided with a shutoff valve 3 for shutting off a gas flow in a gas flow path 2, a gas meter 4 which is a flow sensor on the downstream side of the shutoff valve 3, and a gas chamber or the like where a gas appliance is used. The gas leak detector 5 is installed in the microcomputer 6, and the microcomputer 6 is electrically connected to the gas leak detector 5, the shut-off valve 3, and the gas meter 4 via the flow signal transmitter 7.

The microcomputer 6 is supplied with driving power from a battery 8, and the shutoff valve 3 is connected to a return safety device 9.

The flow signal transmitter 7 changes the mechanical movement of the gas meter 4 into an electric signal each time the gas meter 4 makes one rotation.

The case where the flow signal transmitter 7 is provided in a membrane gas meter will be described. The flow signal transmitter 7 includes a membrane driven by a gas flow, a magnet that rotates in conjunction with the movement of the membrane, And a reed switch that repeats on and off by detecting the movement of the reed.

And when the magnet rotates according to the flow of gas,
When the magnet approaches or moves away from the reed switch, the reed switch turns on and off, and each time the membrane makes one round trip,
That is, each time the magnet makes one rotation, a one-pulse flow signal is transmitted.

The microcomputer 6 includes a first gas leak determination unit 10 for determining a possibility of gas leak based on a flow signal from the flow signal transmitter 7 and a gas detection signal from the gas leak detector 5; The first monitoring means 11 for monitoring the output fluctuation of the signal, the second monitoring means 12 for monitoring the output fluctuation of the flow signal, and the judgment result of the first gas leak judging means 10
Based on the monitoring results of the monitoring means 11 and the second monitoring means 12, a second gas leak determining means 13 for determining whether or not an actual gas is leaking, and based on the determination of the second gas leak determining means 13, And a shut-off signal transmitting means 14 for transmitting a shut-off signal for operating the shut-off valve 3.

Next, a procedure for detecting gas leakage using the above-described automatic gas shut-off device 1 and shutting off the flow of gas in the gas flow path 2 will be described with reference to the flowchart of FIG.

The microcomputer 6 monitors the output fluctuation of the gas detection signal from the gas leak detector 5 by the first monitoring means 11 and monitors the output fluctuation of the flow signal from the flow signal transmitter 7 by the second monitoring means 12.

If no gas detection signal is detected, it is determined that there is no gas leakage.

On the other hand, when the gas detection signal is received, the first gas leak determination means 10 determines whether or not the flow rate signal is received.

Here, when the flow rate signal is not received, it is determined that the gas leak detector 5 has reacted to the miscellaneous gas, for example, the LP gas in the insecticide spray or the alcohol in the breath, and there is no gas leak.

On the other hand, when the flow rate signal is received, it is determined that there is a possibility of gas leakage, and the determination is entrusted to the second gas leakage determination unit 13.

In the second gas leak determination means 13, first, the first monitoring means 11
It is determined whether or not the gas detection signal monitored in step 1 has changed abruptly.

Here, when the gas detection signal changes abruptly, the gas leak detector 5 reacts to miscellaneous gas, for example, LP gas in insecticide spray or alcohol in breath, and the gas leak is Judge that there is no.

On the other hand, when the gas detection signal does not change abruptly, the flow rate signal monitored by the second monitoring means 12 is changed within a certain period of time before the gas detection signal is received, for example, during the last 5 minutes. It is determined whether an output change indicating an increase has occurred.

Here, if there is an output change indicating an increase in the flow rate,
If the gas detection signal output does not decrease for a certain period of time, for example, for 30 seconds, the shut-off signal is transmitted from the shut-off signal transmitting means 14 to the shut-off valve 3, and the monitoring is continued, judging that the gas is leaking. In response, the shutoff valve 3 shuts off the gas flow path 3 to stop the gas flow.

On the other hand, if there is no output change indicating an increase in the flow rate,
Alternatively, the gas detection signal is monitored for 30 seconds, and when the gas detection signal output decreases, the gas leak detector 5 reacts with miscellaneous gas, for example, LP gas in insecticide spray or alcohol in breath, Judge that there is no gas leakage.

<Effects of the Invention> As described above, the automatic gas shut-off device according to the present invention, when the gas leak detector detects the generation of combustible gas, whether it is due to a real gas leak, or due to the influence of miscellaneous gas. It is possible to determine whether or not gas is not used, as well as when using gas, without malfunction, without fail to detect gas leakage reliably The gas flow can be shut off.

[Brief description of the drawings]

1 shows an embodiment of the present invention. FIG. 1 is a schematic block diagram of an automatic gas shut-off device, and FIG. 2 is a flowchart showing a procedure of the present invention. In the figure, 1 ... gas automatic shutoff device, 2 ... gas flow path, 23 ...
... Shutoff valve, 4 ... Gas meter, 5 ... Gas leak detector,
6 microcomputer, 7 flow rate signal transmitter,
8 ... battery, 9 ... return safety device, 10 ... first gas leak determination means, 11 ... first monitoring means, 12 ... second monitoring means,
13 ... second gas leak determination means, 14 ... cutoff signal transmission means.

Claims (1)

(57) [Claims] A gas flow path for supplying a gas; a shutoff valve for shutting off a gas flow in the gas flow path; a flow sensor for detecting a flow of the gas flowing in the gas flow path; A flow signal transmitter for transmitting a flow signal when detecting the flow of a gas, a gas leak detector for detecting a combustible gas and transmitting a gas detection signal, and a gas based on the flow signal and the gas detection signal. First gas leak determination means for determining the possibility of leakage; first monitoring means for monitoring output fluctuations of the gas detection signal; second monitoring means for monitoring output fluctuations of the flow signal; and the first gas A second gas leakage determination unit that determines whether or not gas is leaked based on the monitoring results of the first monitoring unit and the second monitoring unit when the leakage determination unit determines that there is a possibility of gas leakage. And this second gas leak Determining means, when it is determined that gas is leaking, and the shut-off signal transmitter for transmitting a blocking signal for operating the shut-off valve, automatic gas shut-off device, characterized in that it consists of.