JPH0421185Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention relates to an ionization fire detector for ships that can automatically change the dirt alarm level in conjunction with switching the fire alarm sensitivity of the fire detector. .

[Conventional technology]

Ionization type fire detectors having a dirt alarm function are already known from Publication of Utility Model Publication No. 58-3195. If such a conventional ionization type fire detector is provided with a fire detection sensitivity switching function, it will have a configuration as shown in FIG. 2.

In FIG. 2, 1 is an external ion chamber into which smoke flows, 2 is an internal ion chamber as a reference resistance, and the gate of a MOS FET 3 is connected between the external ion chamber 1 and the internal ion chamber 2. This MOS
The drain of FET3 is resistor R1 and operation indicator 62
It is connected to the terminal T1 through the terminal T1.

The source of the MOS FET 3 is connected to the terminal T3 via the resistor R2, and is also connected to the (+) input terminal of the fire detection comparator 41.

Resistors R11, R01,
A series circuit of a fire detection sensitivity switching circuit 42 is connected. The connection point between the resistors R11 and R01 of this series circuit is connected to the (-) input terminal of the fire detection comparator 41.

The fire detection sensitivity switching circuit 42 is composed of a switch SW and resistors R12 and R13.
The movable terminal of SW is connected to the resistor R01 side, and the two fixed terminals are connected to the terminal T3 via resistors R12 and R13, respectively.

The output end of the fire detection comparator 41 is connected to the thyristor 6.
1 and the first input terminal (negative input terminal) of the gate circuit 54.

The gate of thyristor 61 is connected to terminal T3 via resistor R03, and thyristor 61 is connected between terminals T1 and T3.

On the other hand, a resistor R21 is connected between the terminals T1 and T3.
A series circuit of R25 and R25 is connected. The connection point between these resistors R21 and R25 is connected to the (-) input terminal of the dirt detection comparator 51, and the (+) input terminal is
Connected to the source of FET3.

The output of the dirt detection comparator 51 is sent to a timer 53. The output of the timer 53 is output to a second input terminal of a gate circuit 54.

The output terminal of the gate circuit 54 is connected to the gate of the thyristor 71. This gate is resistor R02
It is connected to terminal T3 via. This terminal T
A series circuit of a dirt indicator light 72 and a thyristor 71 is connected between the dirt indicator light 72 and the terminal T2.

Thus, the fire discrimination circuit 4 is constituted by the resistors R11, R01 and the fire detection sensitivity switching circuit 42, and includes the dirt detection comparator 51, the timer 53,
A dirt determination circuit 5 is constituted by the gate 54 and the resistors R21 and R25.

Further, the thyristor 71, the dirt indicator light 72, and the resistor R02 constitute the dirt alarm signal sending circuit 7, and the thyristor 61, the operation indicator light 6,
2. A fire signal sending circuit 6 is constituted by the resistor R03.

Next, the operation will be explained. Connect the switch SW to the resistor R12 (or R13) side. In the case of operation due to dirt, dust accumulates in the external ion chamber, and the voltage drop across the resistor R2 increases in proportion to the amount of dust.
When the reference level is exceeded, the output of the dirt detection comparator 51 is sent to the timer 53, and the timer 53 starts operating.

The output of the dirt detection comparator 51 is continuously input to this timer 53, and after a predetermined period of time has elapsed, the output of the timer 53 is sent to the second input terminal of the gate circuit 54. The gate circuit 54 operates according to the output of the timer 53, ignites the thyristor 71, causes the dirt indicator light 72 to emit light to indicate dirt, and simultaneously outputs a dirt alarm signal to the terminal T2.

On the other hand, the operation in the event of a fire will be explained. In this case, the dirt detection comparator 51 operates first, its output is sent to the timer 53, and the timer 53 starts operating.

Subsequently, the fire detection comparator 41 outputs an output, which causes the thyristor 61 to fire, and the terminal T1
Outputs a fire signal.

Furthermore, the output of the fire detection comparator 41 inhibits the operation of the gate circuit 54. As a result, after a predetermined period of time has elapsed, even if the timer 53 produces an output, the gate circuit 54 does not produce an output.

If the ionization type fire detector for a ship is configured in this way, the fire detection sensitivity can be selected to be optimal for the installation location of the fire detector, that is, the installation environment.

[Problem that the invention attempts to solve]

However, since the dirt alarm level remains fixed, the dirt signal will always be output in the same dirt state regardless of whether the sensitivity is set to high or low.

In reality, it is desirable that the dirt alarm level corresponds to the fire detection sensitivity at that time. In other words, when the sensitivity is high, a dirt signal should be output with less dirt, and when the sensitivity is low, the allowable range for dirt should be expanded compared to when the sensitivity is high.

This idea was developed in consideration of the above points, and it is possible to know in advance whether the detector is dirty according to the fire detection sensitivity, and to increase the reliability of the fire detector, it is linked with the level switching of the fire detection sensitivity. An object of the present invention is to provide an ionization type fire detector for ships that can automatically change the dirt alarm level.

[Means for solving problems]

The ionization type fire detector for ships of this invention has a fire detection sensitivity switching circuit that arbitrarily switches the fire detection sensitivity, and when smoke corresponding to the fire detection sensitivity flows into the external ion chamber, it detects a fire and issues a fire signal. It has a fire discrimination circuit that outputs a fire discrimination circuit, and a dirt alarm level switching circuit that switches the dirt alarm level at the same ratio in conjunction with switching the fire detection sensitivity, and outputs a dirt alarm signal when the dirt in the external ion chamber reaches the dirt alarm level. In addition, a dirt discriminating circuit is provided which blocks the output of the dirt alarm signal when the fire level discriminating circuit detects a fire.

[Effect]

This device links the fire detection sensitivity switching circuit of the fire discrimination circuit and the dirt alarm level switching circuit of the dirt discrimination circuit to switch the fire detection sensitivity and dirt alarm level at the same time. When the level is reached, the dirt detection circuit outputs a dirt alarm signal, and when the fire discrimination circuit detects a fire, it outputs a fire signal and blocks the output of the dirt alarm signal.

〔Example〕

Hereinafter, an embodiment of the ionization type fire detector for ships according to this invention will be described based on the drawings.
FIG. 1 is a circuit diagram showing the configuration of one embodiment. In FIG. 1, parts that are the same as those in FIG. 2 are given the same reference numerals and explanations thereof will be omitted, and parts that are different from those in FIG. 2 will be mainly described.

As is clear from comparing FIG. 1 with FIG. 2, the fire detection switching circuit 4 in the fire discrimination circuit 4
2 is different from Fig. 2, and 3 of resistors R12 to R14
is provided, and the moderation selector switch SW1 allows
These resistors R12 to R14 are designed to be switchable.

The movable terminal of this sensitivity changeover switch SW1 is connected to a resistor R11, and the resistor R01 in FIG. 2 is omitted. A fixed terminal of the sensitivity changeover switch SW1 is connected to a terminal l3 via resistors R12 to R14.

The sensitivity changeover switch SW1 and the level changeover switch SW2 are designed to work together, and the level changeover switch SW2 is provided in the dirt determination circuit 5.

This level selection switch SW2 and resistor R22~
R24 constitutes a dirt alarm level switching circuit 52, and this dirt alarm level switching circuit 52 is included in the dirt discrimination circuit 5.

The movable terminal of level changeover switch SW2 is resistor R.
21 side, and the resistor R25 in FIG. 2 is omitted. The three fixed terminals of this level changeover switch SW2 are connected to the terminal l via resistors R22 to R24.
Connected to 3. In FIG. 1, terminals T1 to T3 in FIG. 2 are designated by terminals l1 to l3.

Thus, the external ion chamber 1, the internal ion chamber 2,
The fire discrimination circuit 4, the dirt discrimination circuit 5, the fire signal sending circuit 6, and the dirt alarm signal sending circuit 7 constitute an ionization type fire detector DE.

Furthermore, in FIG. 1, a receiver RE is connected to this ionization fire detector DE. That is,
A series circuit of a district relay A for fire signal reception and a power supply E is connected between terminals l1 and l3, and a dirt signal reception relay W is connected between the positive terminal of this power supply E and terminal l2. . The other configurations are the same as in FIG. 2.

Next, the operation of the ionization type fire detector for ships of this invention will be explained.

Resistors R12 to R1 of fire detection sensitivity switching circuit 42
4 and the resistance R of the dirt alarm level switching circuit 52
22 to R24, along with resistors R11 and R21, are selected so that the dirt alarm level is a certain ratio to the fire detection sensitivity, for example, 50% (R12<R13<R14, R22<R23<R
24).

First, the switching operation will be explained. In places such as warehouses where the cargo to be stored varies widely,
If the baggage is likely to generate dust, set the sensitivity changeover switch SW1 provided on the ionization fire detector DE to resistor R14.

As a result, the level selection switch SW2 that is linked to the sensitivity selection switch SW1 also moves, and the resistance R24
Connect to. As a result, the fire detection sensitivity is e.g.
to 15%, and the dirt detection level is 50% of that
Automatically set to 7.5%.

When a baggage that does not generate dust is stored, the sensitivity selector switch SW1 of the ionization fire detector DE is switched to the resistor R12. Therefore, the level changeover switch SW2 also moves in conjunction with the changeover to switch to the resistance R22. As a result, the fire detection sensitivity is, for example, 8
%, the dirt detection level is set to 4%.

Next, the operation due to dirt will be explained. When dust accumulates in the external ion chamber 1, the voltage drop V _R2 across the resistor R2 increases in proportion to the amount of dust. When this voltage drop V _R2 exceeds the reference level of the contamination detection comparator 51 (for example, a voltage corresponding to 7.5%), the comparator 51 produces an output.

The timer 53 starts operating based on the output of the comparator 51. When the output of the comparator 51 is continuously input to the timer 53, the timer 53 produces an output when, for example, 5 minutes have elapsed.

The gate circuit 54 is operated by the output of the timer 53 and turns on the thyristor 71. By turning on this thyristor 71, a dirt alarm signal is output.
The dirt indicator light 72 lights up. In response to the dirt alarm signal, the dirt signal receiving relay W of the receiver RE is operated, and a dirt alarm light, a buzzer (not shown), etc. are operated.

Next, the operation in the event of a fire will be explained. In this case, when smoke flows into the external ion chamber 1, the dirt detection comparator 51 operates first and produces an output. This output causes the timer 53 to start operating.

Fire detection comparator 41 then produces an output. This output turns on the thyristor 61,
A fire signal is sent through the operation indicator light 62 and terminal l1. This causes the receiver RE's district relay A to
operates, and fire area indicator lights and alarm bells (not shown) operate.

Furthermore, the output of the fire detection comparator 41 prohibits the gate circuit 54 from operating. As a result, even if the timer 53 produces an output after five minutes, the gate circuit 54 does not produce an output.

[Effect of idea]

As described above, according to the ionization type fire detector for ships of this invention, the fire detection sensitivity switching circuit and the dirt alarm level switching circuit are linked to switch the fire detection sensitivity and the dirt alarm level at the same time, and the fire detection sensitivity and dirt alarm level are simultaneously switched. When the dirt reaches a predetermined dirt alarm level, the dirt detection circuit outputs a dirt alarm signal, and when the fire detection circuit detects a fire, it outputs a fire signal and blocks the output of the dirt alarm signal. The dirt alarm level can be automatically changed in conjunction with switching the sensitivity of the fire detector, and the fire detector can always be used in an appropriate sensitivity state by providing an appropriate dirt alarm depending on the installation environment and aging.

In addition, an appropriate dirt alarm has the effect of preventing non-fire alarms in advance.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the ionization type fire detector for ships according to this invention, and FIG. 2 is a circuit diagram of a conventional ionization type fire detector. 1... External ion chamber, 2... Internal ion chamber, 4
...Fire discrimination circuit, 5...Dirty discrimination circuit, 6...
Fire signal sending circuit, 7... Dirt alarm signal sending circuit, 42... Fire detection sensitivity switching circuit, 52... Dirt level switching circuit, SW1... Sensitivity switching switch, SW2... Level switching switch, DE... Ionization type Fire detector, RE...Receiver.

Claims (1)

[Scope of Claim for Utility Model Registration] An external ion chamber into which smoke flows, an internal ion chamber serving as a reference resistance connected in series with this external ion chamber, and a gate at the connection point between the internal ion chamber and the external ion chamber. It consists of a field effect transistor connected as an impedance conversion element, and a comparator whose one input is connected to the output of the field effect transistor and the other input is connected to a fire detection sensitivity switching circuit that arbitrarily switches the fire detection sensitivity. a fire discrimination circuit that detects a fire and outputs a fire signal when smoke corresponding to its fire detection sensitivity flows into the ion chamber; and a fire signal sending circuit that sends the fire signal output from this fire discrimination circuit to a receiver. a comparator, one input of which is connected to the output of the field effect transistor, and the other input connected to a dirt alarm level switching circuit that switches the dirt alarm level at the same ratio in conjunction with switching of the fire detection sensitivity; , a timer to which the output of this comparator is supplied, and a logic circuit that prohibits the transmission of the output of the timer based on the output of the fire discrimination circuit, when the dirt in the external ion chamber reaches the dirt alarm level. a dirt discrimination circuit that outputs a dirt alarm signal and blocks the output of the dirt alarm signal when the fire discrimination circuit detects a fire; and a dirt alarm signal that sends the dirt alarm signal output from the dirt discrimination circuit to a receiver. An ionization type fire detector for a ship, which is equipped with a sending circuit.