JPH0240528Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial field of application Regarding gas leak alarms, if the gas leak detection function is accidentally or intentionally impaired, a screen may be installed to isolate the gas detection sensor from the outside air. It is used to reliably detect this, issue an alarm, and automatically shut off the gas supply if necessary.

(b) Prior art A gas system that detects gas leaks caused by careless handling of gas appliances, forgetting to close the main valve or appliance valve, or incompletely tightening them, and alerts you to this to prevent explosions caused by gas. Leak alarms are conventionally used. The most basic configuration of this gas leak alarm is as shown in Figures 1 and 2.
A gas detection sensor 2 and a sound generator 3 are housed in the case housing 1, and the gas detection sensor 2 detects the presence of raw gas mixed in the outside air introduced through the vent 5 provided on one side wall of the case housing 1. Detects,
The generator 3 generates a gas leak alarm. Various improvements have been made to such a gas leak alarm 6 to slow down its development. In other words, the gas leak alarm 6 and the gas shutoff valve are linked to issue a gas leak alarm, and the gas is automatically shut off at the main valve before the concentration of the leaked raw gas reaches the lower limit of explosion.
Alternatively, a gas leak detection unit with a built-in gas detection sensor is installed in each room where gas leak detection is required.
A system that centrally monitors the presence or absence of gas leaks at one location and performs alarm operations and gas shutoff operations.Furthermore, in each of the above configurations, various external causes that impair the gas leak detection function, such as power outages and signal transmission lines, can be detected. Some devices have been developed that have a function that automatically shuts off the gas when the alarm is damaged due to disconnection, removal of the alarm, or external impact.

However, although gas leak alarms that have been used in the past have developed extremely advanced functions as described above, it is no exaggeration to say that they are completely defenseless against the blinds that cut off the gas detection sensor from the outside air. In other words, if the vent is blocked intentionally or accidentally, even if a gas leak occurs, it will not be possible to detect it and issue an alarm. No safety effect can be achieved. This is a problem that requires improvement, especially in the current situation where the cause of many gas explosion accidents is gas suicide, where a large amount of gas is intentionally leaked.

Therefore, the present invention has previously devised a structure as shown in FIG. 3, which mechanically detects whether the ventilation opening has been sealed, as a countermeasure for sealing the vent portion. A vent hole 5 provided in a chamber housing a gas detection sensor 2 is constituted by a movable rattle-like member 8 that can be elastically displaced in the inner and outer directions of the sensor housing chamber via a leaf spring 7. 8 is detected by a micro switch 9 or the like.

According to this configuration, when an attempt is made to close the vent hole 5, the louver-like member 8 changes elasticity and the micro switch 9 etc. operate, so that it can be detected that the vent hole 5 is about to be closed. This detection output is used to trigger an alarm, etc., as a countermeasure against blinding. However, since this conventional structure has a mechanical detection mechanism, there are structural limitations on its durability and detection accuracy. It has undetectable defects.

C. Purpose of the invention Electrically detects an external action that intentionally or negligently blocks the ventilation hole provided on one side wall of the storage chamber of the gas detection sensor, that is, the proximity of a human body, etc. to the vicinity of the ventilation hole. It is an object of the present invention to provide a highly reliable device that warns of this and further automatically shuts off the gas as necessary.

D. Structure of the invention The present invention is a gas detection sensor that is housed in a case housing, detects raw gas flowing in through a vent provided on one side wall of the case housing, and whose output voltage changes according to the gas concentration. a first comparator that outputs a gas leak detection signal when the output of the gas detection sensor exceeds a certain level; a metal plate that is disposed in the case housing portion and detects induced hum caused by an object such as an intrusion; a proximity sensor composed of an amplifier that amplifies the induced hum voltage received through a high input impedance circuit; a second comparator that outputs an output for detecting the proximity of a human body, etc. when the output of the proximity sensor exceeds a certain level; To provide a gas leak alarm equipped with a sound generator that issues an alarm when the output of a first or second comparator is received.

E Example The present invention detects gas leaks in multiple locations (each room), centrally monitors them in one location, issues a gas leak alarm, and automatically switches gas to the main valve as needed. An example implemented in a system that shuts off the system will be described below.

In Fig. 4, G, G... are gas leak detection units that are installed in each living room where gas leak detection is required to detect gas leaks and the proximity of human bodies, etc., and C is each gas leak detection unit G, G. A repeater that monitors the presence or absence of a detection signal output from ... and issues an alarm and outputs a gas cutoff signal in the event of an abnormality; ), and when a gas cutoff signal is output from repeater C, the gas is cut off at the main valve.
For example, it is a gas cutoff device using an electromagnetic gas cutoff valve.

An example of the configuration of the gas leak detection section G is shown in FIG. 5. Reference numeral 11 indicates a gas detection sensor consisting of a tin oxide sensor or the like that detects raw gas and changes its output voltage according to the gas concentration, and 12 indicates a gas detection sensor. sensor 11
output at a certain level (e.g. lower explosive limit (LEL))
This is the first comparator that determines whether the gas concentration exceeds 1/4 of the gas leakage detection unit G and outputs a gas leakage detection signal when the gas concentration in the atmosphere surrounding the gas leakage detection unit G exceeds a certain value. N is a proximity sensor composed of a metal plate 13, a high input impedance circuit 14, and an amplifier 15, which will be described later. The metal plate 13 is disposed in the case housing portion of the gas leak detection unit G, particularly in the vent portion of the storage chamber of the gas detection sensor 11, and detects induced hum caused by an object such as a human body. The high input impedance circuit 14 receives the voltage induced in the metal plate 13 through a high resistance R whose one end is grounded and an FET.
Further, the amplifier 15 is a high input impedance circuit 14.
Amplify the voltage received by A second comparator 16 determines whether the output of the amplifier 15 exceeds a certain level and outputs a signal when a human body or the like approaches the gas leak detection section G while trying to reach a vent or the like; outputs 6V to the repeater C through the signal transmission line 18 under normal conditions, and when it detects that a human body approaches the gas leak detection section G and the second comparator 16 outputs an output, it outputs 6V to the repeater C via the signal transmission line 18. Change the output to 0V, detect gas leak, and start the first
When the comparator 12 of
This is an external output signal control circuit that changes the voltage to 12V.
Note that this gas leak detection unit G is supplied with power E from a repeater C, and if the power line 19 is cut intentionally or accidentally, the gas leak detection unit G
The signal voltage output from to repeater C becomes 0V,
The same signal as when the gas leak detection function is impaired is output to repeater C. In other words, power outage, removal of gas leak detection part G, signal transmission line 18 and power line 1
9, the same signal as when a human body or the like comes close to the gas leak detection part G is output to the repeater C.

Next, an example of the structure of repeater C is shown in FIG.
21 is a 12V detection circuit that detects when the signal input from the gas leak detector G becomes 12V; 21 is a 0V detection circuit that detects that the signal input becomes 0V;
Reference numeral 22 indicates an alarm generation circuit that causes the generator 22a to issue an alarm when the 12V detection circuit 20 or 0V detection circuit 21 outputs an alarm, and 23 indicates a delay of the output of the 12V detection circuit 20 for a predetermined period of time, for example, one minute, to prevent gas leakage. A delay circuit 24 is provided to give the person who noticed the alarm a margin to close the gas valve. Under normal conditions, the delay circuit 24 sends a 6V shutoff valve output signal to the gas shutoff device V, and 0V.
A shutoff valve output signal control circuit changes the shutoff valve output signal to 0V when the detection circuit 21 or the delay circuit 23 outputs a shutoff valve output signal, and 25 is a manual shutoff switch provided to manually shut off the gas. When it is turned on, the shutoff valve output signal control circuit 24 is made to output a shutoff valve output signal of 0V. 26 is a power supply circuit that generates and supplies a constant DC voltage necessary for the operation of the repeater C from AC100V.

Next, an example of the configuration of the gas cutoff device V will be described.

In FIG. 7 showing an example of the mechanical structure of the gas cutoff device V, 27 is a valve body provided midway between gas pipes 28 and 29, and 30 is a valve body provided between the valve body 27 and an upstream chamber 27a.
and the downstream chamber 27b; 31 is the partition wall 30;
32 is a valve that opens and closes the opening 31; 33 is slidably inserted into a through hole 34 provided in the wall of the downstream chamber 27b;
The valve 32 is fixed at the tip, and the operating disk 35 is attached at the rear end.
36 is a compression coil spring provided between the outer wall of the downstream chamber 27b and the operating disc 35 to bias the valve 32 in the closing direction; 37 is an annular support rod fixed to the operating disc 35; An iron piece 38 is an annular permanent magnet fixed to the outer surface of the wall of the downstream chamber 27b facing the annular iron piece 37; 39 is an operating disk 35;
An electromagnet 40 is provided above the electromagnet 3 and generates a magnetic field in a direction that cancels the magnetic field of the permanent magnet 38.
A manually operated movable member 41 is slidably disposed within 9 and can be pressed in a direction to open the valve 32, and 41 is an electromagnetic valve drive circuit to be described later that drives the electromagnet 39.

In the gas cutoff device V having the above configuration, when the valve 32 is closed, the valve is kept in the closed state by the elastic action of the compression coil spring 36, and the operating disk 35 is pushed by the movable member 40, as shown in FIG. As shown, when the annular iron piece 37 is attracted to the permanent magnet 38, the attraction force overcomes the elastic force of the compression coil spring 36 to maintain the valve open state. In other words, to close the valve, temporarily use the electromagnet 3.
9 can be excited, and the movable member 40 can be pushed to open the valve.

Next, a configuration example of the above-mentioned solenoid valve control circuit 41 will be explained.

The solenoid valve control circuit 41 shown in FIG. 8 receives a predetermined voltage (for example, 6V) input during normal times when the valve should be kept open, so as to ensure safety even in the event of signal line disconnection or power outage. A signal for closing the valve 32 is received as an input of 0V. and 0V
When receiving the input, it has a function of temporarily supplying an exciting current to the electromagnet 39 using an internal charging voltage.

That is, in FIG. 8, D is a diode, C
1 is the first capacitor with a capacity that can excite the electromagnet 39, SCR is a thyristor, P is a comparator, R1 and R2 are voltage dividing resistors that divide the input voltage, ZD is a Zener diode, and C2 is a Zener diode from the input voltage. The second capacitor R3, which is charged with a voltage value obtained by subtracting the Zener voltage of ZD and provides a reference voltage to one input terminal of the comparator P, is a resistor for discharging the second capacitor C2.

In this configuration, when a normal predetermined voltage of 6V is input, the first capacitor C1 is
It is charged via the diode D and the coil of the electromagnet 39 with its input voltage of 6V. Also, at this time, the input voltage of the comparator P is the voltage divided by the voltage dividing resistors R1 and R2, which is connected to the second capacitor C2.
Since the charging voltage is higher than the charging voltage of , comparator P does not output and thyristor SCR is in a cut-off state. If it is detected that the gas is about to be sealed, or if the gas leak detection function is impaired due to a signal line disconnection or power outage, and the shutoff valve output signal changes to 0V, the voltage at the midpoint of the voltage dividing resistors R1 and R2 will increase. is 0V
, which is lower than the charging voltage of the second capacitor C2. And comparator P is a thyristor
The bird outputs voltage to the SCR. As a result, the thyristor SCR becomes conductive and discharges the charge in the first capacitor C1 to the coil of the electromagnet 39. As a result, the electromagnet 39 is energized to cancel the magnetic field of the permanent magnet 38 in the state shown in FIG. 7, and the compression spring 36 closes the valve 32. The excitation operation of the electromagnet 39 is performed by the first capacitor C.
When the first discharge ends, the thyristor SCR enters the cutoff state and stops, but after this, the valve closed state is maintained by the elastic action of the compression coil spring 36 mentioned above. After this, after the cause of the gas cutoff has been removed, by pushing the movable member 40,
The valve can be returned to the open state as shown in FIG. 7 again.

In addition to the above-mentioned implementation of the present invention as a gas cutoff system linked to a gas leak alarm,
There are various implementations. In short, the present invention is characterized by having a gas leak detection section with a built-in proximity sensor.To give an example of another embodiment, for example, a proximity sensor is built into one gas leak alarm. A system equipped with a gas leak detection section and a sound generator and used alone, or a system shown in Fig. 4 that does not use a gas cutoff device V and only issues an alarm through centralized monitoring. There are things etc.

C. Effects of the invention The gas leak alarm of the invention has a proximity sensor built-in in the gas leak detection section consisting of a gas detection sensor, which detects changes in induced hum caused by the proximity of a human body, etc. If you try to touch the gas leak detector, this will be detected and an alarm will be issued, and if necessary, the gas can be shut off automatically. In particular, the detection of the present invention is performed by electrical action and has no moving parts due to mechanical construction, so it has excellent stability and reliability. Therefore, it is possible to completely take measures against blind spots, which have been a blind spot in the safety measures of conventional devices. This proximity sensor can also detect other effects that may impair the gas detection function, such as damage to the gas leak detector or attempts to remove it. The reliability and safety effect of the equipment can be improved.

Furthermore, in the gas leak alarm interlocking gas cutoff system of the present invention, the detection signal generated by the proximity of a human body and output to the repeater C, and the gas cutoff signal output to the gas cutoff device V are each set to a voltage of 0V. Therefore, even if the gas leak detection function is impaired due to power outage, disconnection of the signal transmission line, or removal or damage of the gas leak alarm, the alarm issuing operation and gas shutoff operation can be performed reliably.

Furthermore, the repeater C of the above embodiment is provided with a delay circuit 23 that delays the output from the 12V detection circuit 20 when a gas leak is detected by a predetermined period of time, for example, one minute. This system has a practical function in that it allows the person who notices the gas leak warning to close the gas valve at that location. That is, if the gas is shut off immediately upon detection of a gas leak, it is necessary to go to the gas shutoff device V and perform a reset operation each time, which is inconvenient.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing an example of a conventional gas leak detector, Fig. 2 is a sectional view showing the structure of its gas leak detection section, and Fig. 3 is an improved structure of the conventional gas leak detection section. 4 to 8 each show an embodiment of the present invention, FIG. 4 is a block diagram showing its overall configuration, FIG. 5 is a circuit diagram showing the configuration of the gas leak detection section, and FIG. The figure is a circuit diagram showing the structure of the repeater, FIG. 7 is a sectional view showing the structure of the gas cutoff device, and FIG. 8 is a circuit diagram of the solenoid valve drive circuit. 11... Gas detection sensor, 22a... Sound generator, N... Proximity sensor, G... Gas leak detection section, C... Repeater, V... Gas cutoff device.

Claims (1)

[Scope of claim for utility model registration] A gas detection sensor that is housed in a case housing, detects raw gas flowing in through a vent provided on one side wall of the case housing, and whose output voltage changes according to the gas concentration. a first comparator that outputs a gas leak detection output when the output of the gas detection sensor exceeds a certain level; a metal plate that is placed in the case housing and detects induced hum caused by an object such as an entry; a proximity sensor composed of an amplifier that amplifies the induced hum voltage received through a high input impedance circuit; a second comparator that outputs an output for detecting the proximity of a human body, etc. when the output of the proximity sensor exceeds a certain level; 1. A gas leak alarm comprising a sounding device that issues an alarm when the output of the first or second comparator is received.