JPH0423169B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a gas cut-off device that guarantees the overall safety of gas supply.

BACKGROUND ART In recent years, gas has been widely used in homes, but one mistake can lead to a gas accident, so devices that ensure the safety of gas supply are becoming more important.

An example of a conventional gas cutoff device will be described below with reference to FIG.

In FIG. 2, 1 is a gas meter, 2 is a flow rate sensor attached to the gas meter 1, 3 is a control unit whose main component is a microcomputer, 4 is a cutoff valve drive circuit, and 5 and 6 are a cutoff valve drive circuit 4. A resistor and a transistor, 7 a cutoff valve for a gas path 7a leading to the gas meter 1, 8 a battery as a power source for the control section 3, and 9 a voltage detection circuit for detecting the voltage of the battery 8.

The operation of the gas cutoff device configured as described above will be described below. Gas flows as shown by the arrow, and a gas flow rate signal is transmitted from the flow rate sensor 2 to the control unit 3. When there is an abnormality in the gas flow rate or when a certain flow rate continues for an abnormal time, the control unit 3 operates the cutoff valve drive circuit 4 and operates the cutoff valve 7 to cut off the gas passage 7a. Further, the voltage detection circuit 9 detects whether the battery 8 has the ability to drive the cutoff valve 7 or not based on the battery voltage. Before the voltage of the battery 8 drops and the ability to drive the cutoff valve 7 is lost, the voltage detection circuit 9 detects the drop in battery voltage and informs the control unit 3, which in turn controls the cutoff valve drive circuit 4.
The shutoff valve 7 is operated to shut off the gas passage 7a.

Problems to be Solved by the Invention However, in the conventional battery voltage check,
Since the voltage is measured when the load on the battery 8 is a small current flowing only from the control unit 3, if the battery 8 reaches the end of its capacity or the internal resistance increases for some reason, a large current will be detected. The voltage detection circuit 9 cannot detect this even though the pulse characteristics of the cutoff valve 7 have deteriorated and the driving ability of the cutoff valve 7 has been lost. In such a state, the gas cutoff device
Even if the shutoff valve 7 operates normally and the shutoff valve 7 is driven, the shutoff valve 7 will not operate and the gas passage 7a will remain open, thus failing to function as a safety device.

Means for Solving the Problems In order to solve the above problems, the gas cutoff device of the present invention detects the voltage of the cutoff valve equivalent resistance, which is a pseudo resistance of the cutoff valve, the cutoff valve equivalent resistance drive circuit, and the cutoff valve equivalent resistance. It is equipped with a circuit.

Effects The present invention tests whether the battery can maintain the necessary voltage when driving the shutoff valve by operating the shutoff valve equivalent resistance drive circuit and energizing the shutoff valve equivalent resistance. can be detected.

Embodiment A gas cutoff device according to an embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, parts designated by numerals 1 to 8 are the same parts as those described in the conventional example. 10 is a cutoff valve equivalent resistance, which has a resistance value equivalent to that of the cutoff valve 7. Reference numeral 11 denotes a cutoff valve equivalent resistance drive circuit, which energizes the cutoff valve equivalent resistance 10. 12,13
are the resistors and transistors that constitute the cutoff valve equivalent resistance drive circuit 11.

9 is a voltage detection circuit that detects the voltage of the cutoff valve equivalent resistance 10.

The operation of the gas cutoff device configured as described above will be described below.

First, when the control unit 3 checks the voltage of the battery 8, the cutoff valve equivalent resistance drive circuit 11 is activated and the cutoff valve equivalent resistance 10 is energized. Check the voltage of the battery 8 by applying the same load as when it was activated. If the detection level of the voltage detection circuit 9 is set just before the voltage of the battery 8 at this time reaches the operation guarantee voltage of the cutoff valve 7, even if the battery 8 loses its ability to drive the cutoff valve 7, the battery This can be detected by the voltage detection circuit 9 and the cutoff valve 7 can be driven to cut off the gas passage 7a.

Effects of the Invention As described above, the present invention makes it possible to reliably detect the battery voltage before it becomes impossible to drive the shutoff valve, even if the battery's large current pulse characteristics deteriorate due to the terminal capacity of the battery or some other cause. Because you can
The device can always be kept in a safe operating condition.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a gas cutoff device which is an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional example. 2...Flow rate sensor, 3...Control unit, 4...Shutoff valve drive circuit, 7...Shutoff valve, 8...Battery, 9...
Battery voltage detection circuit, 10...Shutoff valve equivalent resistance, 1
1...Shutoff valve equivalent resistance drive circuit.

Claims (1)

[Claims] 1. A gas flow rate sensor and a cutoff valve provided in a gas passage, and a cutoff valve drive circuit that drives the cutoff valve,
A control section that controls the cutoff valve in response to a signal from the flow rate sensor, a battery as a power source for the control section, a cutoff valve equivalent resistance that is a resistance equivalent to the cutoff valve, and a control section that controls the cutoff valve. A gas cutoff device comprising: a controlled cutoff valve equivalent resistance drive circuit; and a voltage detection circuit that detects a voltage of the cutoff valve equivalent resistance and transmits it to the control section.