JPH0460298A - Automatic gas-blast circuit-breaker - Google Patents

Abstract

PURPOSE:To prevent malfunction of a gas-blast circuit-breaker by effect of miscellaneous gas by composing the breaker of a flow sensor, a flow signal generator, a gas leak detector, a first gas leak decision means, a first monitoring means of gas detecting signal, a second monitoring means of flow signal, a second gas leak decision means and a circuit breaking signal generating means. CONSTITUTION:An automatic gas-blast circuit-breaker 1 is provided with a gas meter 4 serving as a flow meter at a gas-blast circuit-breaking valve 3 in a gas passage 2. A microcomputer 6 has a first gas leak decision means 10 which decides according to a signal from a flow signal generator 7 and a gas leak detector 5, a first and a second monitoring means 11, 12 of a gas detecting signal and a flow signal, a second gas leak decision means 13 which decides gas leakage, according to results of the first and second monitoring means 11, 12 and a circuit-breaking signal generating means 14 of the circuit- breaking valve 3 according to the decision of the second gas leak decision means 13. As a result, leakage of gas can be detected and thus gas circuit broking is carried out.

Description

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

<Prior Art> A conventional gas automatic shutoff device shuts off the flow of gas when a gas leak detector detects flammable gas.

In order to prevent the gas leak detector from malfunctioning due to reaction with miscellaneous gases, such as LP gas in pesticides or alcohol in exhaled breath, the detector determines whether gas is being used and if gas is not being used. Japanese Patent Laid-Open No. 63-296198, filed by the present applicant, discloses an automatic gas leak shutoff device that is constructed so as not to determine that there is a gas leak even if a gas leak detector reacts to the gas leak.

<Problems to be Solved by the Invention> However, the conventional gas leakage automatic shutoff device described above can prevent the gas leakage shutoff device from malfunctioning due to miscellaneous gas when gas is not in use; If so, the gas leak cutoff device may malfunction because it is not possible to distinguish between a real gas leak and an effect caused by miscellaneous gas.

Means for Solving the Problems The present invention was proposed in view of the above, and is intended to prevent a gas cutoff device from malfunctioning due to the influence of miscellaneous gases. A flow rate sensor that detects the flow of gas, a flow signal transmitter that transmits a flow signal when the flow sensor detects a gas flow, and a gas leak detector that detects combustible gas and transmits a gas detection signal. a first gas leak determining means for determining the possibility of gas leak based on the flow rate signal and the gas detection signal; a first monitoring means for monitoring output fluctuations of the gas detection signal; and a first monitoring means for monitoring pressure fluctuations of the flow rate signal. A second gas leak that determines whether or not gas is actually leaking based on the second monitoring means, the judgment result of the first gas leak judgment means, and the monitoring result of the first monitoring means and the second monitoring means. It is characterized by comprising a determining means and a shutoff signal transmitting means for transmitting a shutoff signal for shutting off the shutoff valve based on the determination by the second gas leakage determining means.

<Function> The flow rate sensor monitors the gas flow in the gas flow path, and when the gas flow is detected, the flow rate signal transmitter emits a flow rate signal.

A gas leak detector monitors the generation of flammable gas, and when it detects flammable gas, it issues a gas detection signal.

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

The first gas leak determination means performs calculation based on the flow rate signal and the gas detection signal, and determines that there is a possibility of gas leakage when the gas detection signal and the flow rate signal are detected.

When there is a possibility of a gas leak, the second gas leak determination means performs calculations based on the monitoring results of the first monitoring means and the second monitoring means, and detects gas due to a gas leak or gas due to miscellaneous gas. distinguish between

If it is determined that gas is detected due to gas leakage, the cutoff signal transmitting means transmits a cutoff signal to the cutoff valve to cut off the flow of gas in the gas flow path.

<Example> Hereinafter, the present invention will be described in detail based on the drawings.

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

This gas automatic shutoff device 1 is equipped with a shutoff valve 3 for shutting off the flow of gas in a gas flow path 2, a gas meter 4 as a flow rate sensor on the downstream side of the shutoff valve 3, and is installed in a room where gas appliances are used, etc. A gas leak detector 5 is installed in the gas leak detector 5, and a gas meter 4 is electrically connected to the microcomputer 6 via the gas leak detector 5, the cutoff valve 3, and the flow rate signal transmitter 7.

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

The flow rate signal transmitter 7 described above converts the mechanical movement of the gas meter 4 into an electrical signal every time the gas meter 4 rotates once. To explain the case where this flow rate signal transmitter 7 is installed in an abdominal type gas meter, the flow rate signal transmitter 7 consists of a membrane that is driven by the flow of gas, a magnet that rotates in conjunction with the movement of this membrane, and a magnet that rotates in conjunction with the movement of this membrane. It consists of a reed switch that detects movement and turns on and off repeatedly. When the magnet rotates in response to the gas flow, the magnet approaches or moves away from the reed switch, turning the reed switch on and off. Sends a pulsed flow signal.

The microcomputer 6 mentioned above is perfect! a first gas leak determining means 10 that determines the possibility of gas leak based on the flow rate signal from the signal transmitter 7 and the gas detection signal from the gas leak detector 5; a monitoring means 11 and a second monitoring means 11 for monitoring output fluctuations of the flow rate signal;
Based on the monitoring means 12, the judgment results in the first gas leakage judgment means 10, and the monitoring results in the first monitoring means 11 and the second monitoring means 12, a second judgment is made as to whether or not gas is actually leaking. It has a gas leak determining means 13 and a shutoff signal transmitting means 14 for transmitting a shutoff signal for shutting off the shutoff valve 3 based on the determination by the second gas leak determining means.

Next, a procedure for detecting a gas leak and shutting off the flow of gas in the gas passage 2 using the automatic gas shutoff device 1 described above will be described based on the flowchart in FIG.

The microcomputer 6 monitors the gas detection signal from the gas leak detector 5 and the flow rate signal from the flow rate signal transmitter 7.

Further, the first monitoring means 11 monitors output fluctuations of the gas detection signal, and the second monitoring means 12 monitors output fluctuations of the flow rate signal.

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

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

Here, if the flow rate signal is not received, the gas leak detector 5 determines that the gas has reacted with miscellaneous gas, such as LP gas in an insecticide spray or alcohol in breath, and that 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 determining means.

The second gas leak determining means first determines whether the gas detection signal monitored by the first monitoring means 11 has detected a sudden change in output.

Here, if the gas detection signal shows a sudden change in output, the gas leak detector 5 has reacted to miscellaneous gas, such as LP gas in insecticide spray or alcohol in breath, and there is no gas leak. I judge that there is no.

On the other hand, if the gas detection signal does not show a sudden change in output, the flow rate signal monitored by the second monitoring means 12 may change within a predetermined period of time before receiving the gas detection signal, e.g.
Determine whether there is a change in output that indicates an increase in flow rate within a minute.

Here, if there is a change in the output indicating an increase in flow rate, it is determined that gas is leaking and monitoring is continued, and if the gas detection signal output does not decrease for a certain period of time, for example 30 seconds, a cutoff signal is issued. The means 14 sends a cutoff signal to the cutoff valve 3, and in response, the cutoff valve 3 cuts off the gas flow path 2 and stops the flow of gas.

On the other hand, if there is no output change indicating an increase in flow rate, the gas leak detector 5 detects miscellaneous gas, for example, L during insecticide spray.
It was determined that there was no gas leak as it was a reaction to P gas and alcohol in breath.

<Effects of the Invention> As explained above, the automatic gas shutoff device according to the present invention detects whether the gas leak is due to a real gas leak or due to the influence of miscellaneous gas when the gas leak detector detects the generation of flammable gas. Able to distinguish and judge.

Therefore, of course if you are not using gas,
Even when gas is used, the gas automatic shutoff device does not malfunction and can reliably detect gas leakage and shut off the gas flow.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a schematic block diagram of an automatic gas shutoff device, and FIG. 2 is a flowchart showing the procedure for implementing the present invention. In the figure, 1... gas automatic shutoff device, 2... gas flow path,
3... Shutoff valve, 4... Gas meter, 5... Gas leak detector, 7... Flow rate signal transmitter, 10... First gas leak determining means, 11... First monitoring means , 12...
Second monitoring means, 13...Second gas leakage determining means, 14
... Cutoff signal transmission means. Figure 1

Claims (1)

[Claims] In a gas flow path equipped with a shutoff valve, a flow rate sensor that detects the flow of gas flowing in the gas flow path, and a flow rate signal generator that transmits a flow rate signal when the flow rate sensor detects the flow of gas. a gas leak detector that detects combustible gas and transmits a gas detection signal; a first gas leak determination means that determines the possibility of a gas leak based on the flow rate signal and the gas detection signal; and a gas detection signal. a first monitoring means for monitoring output fluctuations of the flow rate signal; a second monitoring means for monitoring output fluctuations of the flow rate signal; a determination result in the first gas leak determination means; and a monitoring result in the first and second monitoring means. a second gas leak determining means for determining whether or not gas is actually leaking based on the second gas leak determining means; and a shutoff signal for transmitting a shutoff signal for shutting off the shutoff valve based on the determination of the second gas leak determining means. An automatic gas shutoff device comprising: a transmitting means;