JPH0430864A - Automatic gas shut-off device - Google Patents

Abstract

PURPOSE:To provide an automatic gas shut-off device having a shut-off valve surely operated without defectively shutting off gas in abnormal gas flow by inspecting a drive coil of the shut-off valve with a detecting means according to an abnormality detecting signal of a control means under the inoperative condition of the shut-off valve. CONSTITUTION:Normally, an output terminal P2 is in H level and a transistor Tr2 is under the nonconducting condition. When the output terminal P2 is set to L level by an abnormality detecting signal, the transistor Tr2 is made conductive and connected to a collector of the transistor Tr2 through a limit resistor RL to supply current to a drive coil 24 of a shut-off valve 3. When the DC resistance of the drive coil 24 is set to RC smaller than RL, the shut-off valve 3 is not operated. When voltage level of VC is judged by a control circuit 1 and the drive coil 24 is disconnected, current does not flow through the drive coil 24 even if the transistor Tr2 is under the conductive condition. When the drive coil 24 is not disconnected, an input terminal P3 of a control circuit 1 is in H level and the output terminal P2 is in L level under the conductive condition of the transistor Tr2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Industrial Application Field) The present invention relates to an automatic gas shutoff device capable of detecting an abnormality in a shutoff valve.

(Prior Art) An automatic gas shutoff device must reliably shut off gas in the event of an abnormal gas flow rate, an abnormally long use of gas equipment, a gas leak, or a major earthquake.

In a conventional automatic gas shutoff device, when a control section detects an abnormality in the gas flow rate, the drive coil of the shutoff valve is energized to operate the shutoff valve.

(Problems to be Solved by the Invention) The conventional device described above cannot detect a disconnection of the drive coil of the shutoff valve, so if the drive coil is disconnected, the shutoff valve may fail to shut off, leading to a serious accident. .

SUMMARY OF THE INVENTION An object of the present invention is to provide an automatic gas cutoff device that can reliably operate a cutoff valve in the event of an abnormality by periodically monitoring disconnection of the drive coil of the cutoff valve.

[Structure of the Invention] (Means for Solving the Problem) In order to achieve the above object, the present invention provides a cutoff valve that cuts off gas when the gas flow rate is abnormal, and a signal that outputs a signal for detecting abnormality of the cutoff valve. The present invention includes a control means and a detection means for detecting an abnormality in the shutoff valve while the shutoff valve is in an inoperable state based on an abnormality detection signal from the control means.

(Function) In such a configuration, when inspecting the disconnection of the drive coil of the shutoff valve, the detection means detects the disconnection of the drive coil of the shutoff valve with the shutoff valve in an inoperable state based on the abnormality detection signal of the control means. By doing so, it is possible to prevent failures in shutting off and to reliably shut off the gas when the gas flow rate is abnormal.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

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

Reference numeral 1 denotes a control circuit that outputs a cutoff signal for operating the cutoff valve 3 and an abnormality detection signal for checking for disconnection of the drive coil of the cutoff valve 3.

Reference numeral 2 designates a cutoff valve drive circuit. When a gas flow rate is abnormal due to a cutoff signal from the output terminal Pl of the control circuit 1, the transistor Trl of the cutoff valve drive circuit 2 becomes conductive, and a voltage vDD is applied to the drive coil of the cutoff valve 3 to shut it off. perform an action.

In Section 22, the operation of the shutoff valve 3 will be explained with reference to FIG. 21 attracts the valve 22 by a magnetic field generated by a permanent magnet.

A spring 23 normally holds the valve 22 in a compressed state.

24 is a drive coil, which is a shutoff valve drive circuit 2 based on the control circuit 1.
The valve 22 is actuated by the force of the spring 23, which is excited by the output signal of the spring 23 and cancels the magnetic field of the permanent magnet.

4 is a detection circuit, and a transistor Tr2 of the detection circuit 4 is operated by an abnormality detection signal from an output terminal P2 of the control circuit 1.

Normally, the output terminal P2 is at H level and the transistor Tr
2 is a non-conducting state. Here, when the output terminal P2 is set to L level by the abnormality detection signal of a predetermined period, the transistor "
r2 becomes conductive, and current flows through the drive coil 24 of the cutoff valve 3, which is connected to the collector of the transistor Tr2 via the limiting resistor RL. Here, if the DC resistance of the drive coil 24 is Rc, the voltage vc applied to the drive coil 24 is expressed by equation (1).

If RL>Ro in equation (1), the following is obtained.

(2) Therefore, the cutoff valve 3 does not operate (at this time, the transistor "rl is non-conductive)."

Further, the drive coil 24 is connected to the input terminal P3 of the control circuit 1 in addition to the collector side of the transistor "rl" of the cutoff valve drive circuit 2.
The control circuit 1 determines the voltage level of VC.

If the drive coil 24 is disconnected, the transistor T
Even if r2 becomes conductive, no current flows and therefore there is no voltage drop due to the limiting resistor R.

"vDD" and the input terminal P3 of the limiting circuit 1 becomes H level.

Next, if the drive coil 24 is not disconnected, current will flow if the transistor Tr2 becomes conductive (2).
As shown in the equation, V ('x Q), and the input terminal P2 becomes L level.

Although not shown, a communication output section and an alarm section can be connected to the control circuit 1 to call the center and issue an alarm when the drive coil 24 of the cutoff valve 3 is disconnected, or to issue an alarm by sound or display. It is also possible to

[Effects of the Invention] According to the present invention, it is possible to periodically monitor whether or not the shutoff valve is malfunctioning while the shutoff valve is in an inoperable state. It is possible to obtain an automatic gas shut-off device that can operate the shut-off valve.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an automatic gas shutoff device of the present invention, and FIG. 2 is a sectional view of a cutoff valve of the automatic gas shutoff device. 1...Control circuit 2...Shutoff valve drive circuit 3...Shutoff valve 4...Detection circuit 24...Drive coil

Claims (1)

[Scope of Claims] A shutoff valve that shuts off gas when the gas flow rate is abnormal; a control means that outputs a signal for detecting an abnormality in the shutoff valve; and detection means for detecting an abnormality of the shutoff valve in an operating state.