JPH03213781A - Automatic cut-off device for gas - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION (Field of Industrial Application) The present invention relates to an automatic gas shutoff device that accurately detects power supply voltage.

(Prior Art) Automatic gas shutoff devices cannot use an external AC power source due to installation conditions, so lithium batteries are often used as a power source. Therefore, it is necessary to determine the capacity life of the lithium battery so that the shutoff valve can operate reliably.

A conventional automatic gas shutoff device connects a voltage comparator to a lithium battery, and monitors the output level of the lithium battery at regular intervals using an arithmetic circuit to determine the capacity life of the lithium battery.

(Problems to be Solved by the Invention) The conventional device described above cannot monitor changes in the internal impedance of a lithium battery, which increases as the capacity of the lithium battery decreases, with a small current consumption during normal operation. This is because when the current consumption is small, the battery voltage hardly changes even if the internal impedance increases.
Unable to detect battery voltage drop.

An object of the present invention is to provide an automatic gas cutoff device that can reliably drive a cutoff valve by periodically monitoring the power supply voltage.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention outputs a cutoff valve that cuts off the gas when the power supply and gas flow rate is abnormal, a signal that operates the cutoff valve, and a signal that detects the voltage of the power supply. control means;
It is comprised of a switching means that causes a current to flow through the cutoff valve in an inoperable state in response to a voltage detection signal from the control means, and a comparison means that compares the voltage of the power supply detected by the current from the switching means with a predetermined voltage.

(Function) This automatic gas shutoff device supplies current to the power supply in the same magnitude and opposite direction as when the shutoff valve is operating, detects the power supply voltage, and replaces the power supply when this output level falls below a predetermined level. , it is possible to prevent the shutoff valve from operating due to a drop in power supply voltage.

(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.

1 is a lithium battery, which is the power source for the automatic gas cutoff device.

Reference numeral 2 denotes a control circuit that periodically outputs a control signal when detecting the voltage of the power source 1 and controls the switching circuit 3 so that the current flows in the opposite direction to the drive current that operates the cutoff valve 5.

The switching circuit 3 includes PNP transistors Tr, .
Tr3. N P N )-transistor Tr2. Tr4
Consists of. The emitter sides of the transistors Tr1 and Tr3 are connected to the positive side (voltage Voo) of the lithium battery 1.

The emitters of transistors Tr2 and Tr are grounded.

Further, the base sides of the transistors Tr1 and Tr2 are connected to the output terminal P1 of the control circuit 2, and the transistors Tr,
And the base side of Tr4 is connected to output terminal P2.

When operating the shutoff valve 6 when the gas flow rate is abnormal, the control circuit 2 outputs a LOW level signal at the output terminal PY and an H level signal at the output terminal P2. When this signal is output, transistors Tr□ and Tr4 become conductive, and transistors Tr2 and Tr
becomes non-conductive, and a drive current flows from the transistor Tr through the cutoff valve 6 to the transistor Tr4. In this case, current flows through the shutoff valve 6 and it operates.

When detecting the voltage of the power supply 1, the control circuit 2 outputs the output terminals P and 1'.
It periodically outputs a HI level signal and a LOW level signal at the output terminal P2. When this signal is output, transistors Tr2 and Tr3 are conductive, and transistors Tr1 and Tr are non-conductive. In this case, a current equivalent to the above-mentioned driving current flows from the transistor Tr3 to the transistor Tr2 via the cutoff valve 6, although in the opposite direction to that when the cutoff valve 6 operates. In this way, a voltage value that changes due to a decrease in the internal impedance of the power source 1 is detected. Note that the cutoff valve 6 does not operate in this current direction.

4 is a voltage comparator, and the input side is a switching circuit 3
The collector side of the transistor Tr3 is connected to the output terminal P3 of the control circuit 2.

When detecting the voltage of the power source 1, the voltage of the power source 1 is input through the transistor Tr3, and if this voltage value is above a predetermined voltage value, the signal is set to VDD level, and if it is below the predetermined voltage value, a zero level signal is sent to the control circuit 2. Output to output terminal P3.

A display section 5 outputs a signal from the control circuit 2 when the voltage drop of the lithium battery 1 exceeds a predetermined level to display an alarm.

Next, the operation of the cutoff valve 6 will be explained with reference to FIG. 2.

Reference numeral 21 denotes an electromagnetic coil, which generates magnetic fields in opposite directions by the current flowing from the Tr of the switching circuit 3 and the Tr 3. 22 is a permanent magnet, which attracts the valve by the generated magnetic field. When this magnetic field is canceled out by the magnetic field generated by the electromagnetic coil 21, the valve is moved in the direction of the arrow by the force of the spring 23, closing the valve.

Therefore, if a current is passed so that the magnetic field generated by the electromagnetic coil 21 does not cancel the magnetic field of the permanent magnet 22, the valve will not move in the closing direction, and at this time the power supply voltage can be detected.

〔Effect of the invention〕

According to the present invention, the current flowing through the shutoff valve is made to flow in the opposite direction to that during operation, and the power supply voltage is periodically monitored without operating the shutoff valve, so that the valve is automatically shut off due to a drop in the power supply voltage without causing malfunction. A gas cut-off device can be obtained.

[Brief explanation of drawings]

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.

Claims (1)

[Scope of Claims] A power supply, a cutoff valve that shuts off the gas when the gas flow rate is abnormal, a control means that outputs a signal for operating the cutoff valve and a signal for detecting the voltage of the power supply, and a voltage from the control means. An automatic gas cutoff device comprising: switching means for causing current to flow through the cutoff valve in an inoperable state in response to a detection signal; and comparison means for comparing the voltage of the power supply detected by the current from the switching means with a predetermined voltage.