Fire-fighting device

Abstract

Fire-fighting device with at least one generator arranged for discharging fire-fighting agent, an electrically triggerable ignition means arranged in the generator, the ignition means being controllable via an at least two-pole control connection. A bypass circuit electrically arranged at the control connection detects a triggering of the ignition means and closes a switch when the ignition means is released.

Claims

1. A fire-fighting device comprising: at least one generator arranged for discharging a fire-fighting agent; an electrically triggerable ignition arranged in the generator, wherein the ignition has an at least two-pole control connection; a bypass circuit electrically arranged at poles of the control connection; and a switch, wherein the bypass circuit is arranged to monitor an ohmic resistance across the ignition and is connected to the switch in such a way that it closes the switch, to connect the poles of the control connection so as to allow a current to flow between the poles of the control connection across the switch, depending on the resistance across the ignition, and that the bypass circuit is connected to the control connection electrically in parallel.

2. Fire-fighting device according to claim 1, wherein the bypass circuit monitors a current through the ignition and in that the bypass circuit closes the switch for a detected current below a limit value.

3. Fire-fighting device according to claim 1, wherein the bypass circuit has an asymmetrically connected current mirror.

4. Fire-fighting device according to claim 1, wherein the switch is an electronic switch.

5. Fire-fighting device according to claim 1, wherein the at least one generator is a solid aerosol generator.

6. Fire-fighting device according to claim 1, wherein the ignition is a pyrotechnic ignition which can be ignited electrically via a resistance wire.

7. Fire-fighting device according to claim 1, wherein the control connection is formed for an input voltage between 16.8 V and 30 V.

8. Fire-fighting device according to claim 1, wherein a circuit for storing an ignition process is arranged electrically in series with the ignition, wherein the circuit has at least one fuse which triggers during an ignition process and a switch which bypasses the fuse.

9. Fire-fighting device according to claim 8, wherein the switch bypassing the fuse is configured to be open during a monitoring mode.

10. A system comprising a control circuit and at least two of the fire-fighting device according to claim 1 electrically connected in series to the control circuit.

11. A method for operating the system of claim 10, comprising: in a monitoring mode, providing a measuring current by the control circuit, wherein the measuring current is smaller than an ignition current; providing the ignition current by the control circuit in an ignition mode; igniting by the ignition current at least one ignition of a first of the fire-fighting devices; and activating the monitoring circuit associated with the ignited ignition depending on a resistance across the ignition, so that the switch closes and thereby the ignition current flows through at least a second of the fire-fighting devices after the ignition of the first of the fire-fighting devices is ignited.

12. Method according to claim 11, wherein the circuit for storing an ignition process is activated by the ignition current in such a way that a switch of the circuit for storing the ignition process is open in the case of a measuring current and in that the switch is closed in the case of an ignition current which is greater than the measuring current.

13. A rail vehicle equipped with the system according to claim 10.

14. The rail vehicle of claim 13, wherein the control circuit is fed by a voltage source of the rail vehicle, wherein a voltage band of the voltage source is between 16.8 V and 30 V.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, the subject matter is explained in more detail by means of a drawing showing embodiments. In the drawing show:

(2) FIG. 1 a system with a control circuit and a row of fire-fighting devices;

(3) FIG. 2 an embodiment of a circuit on a control connection of a fire-fighting device.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

(4) FIG. 1 shows in a schematic block diagram a system with a control circuit 2, for example a fire alarm system or fire-fighting system, connected to a number of fire-fighting devices 4, each with at least one circuit 6 comprising a bypass circuit and a generator 8. The control circuit 2 has a digital control output with two poles 2a, 2b. The fire-fighting devices 4 are electrically connected in series to the control circuit 2.

(5) In case of a fire, when a fire is to be fought or extinguished, it is necessary that if possible all generators 8 of control circuit 2, which are electrically connected in series, actually trigger. Since the generators 8 are connected in series, this is not always the case of conventional systems.

(6) In a generator 8, which can be an aerosol generator, an ignition means can be arranged, for example an ignition wire, which is heated by a current flow and triggers a pyrotechnical ignition.

(7) The current flow is caused by the ignition current between the poles 2a, 2b.

(8) At the moment when an ignition means of a generator 8 triggers, an electrical disconnection can occur in the ignition means, for example in the ignition wire. However, this leads to an interruption in the current flow between the poles 2a, 2b.

(9) If in this case the ignition means of the other generators 8 along the line are not yet sufficiently heated and activated for ignition, this disconnection can cause the ignition process in the other generators 8 to be interrupted and they will not ignite any more.

(10) This problem is arises in particular when the voltage at poles 2a, 2b is variable, for example in the case of applications in rail vehicles. There, the control circuit 2 is connected to the internal voltage supply of the rail vehicle, which has a relatively high fluctuation range of for example at least 10 V. This fluctuation range of the voltage leads to different currents in the ignition means of the generators 8, so that the duration of the current flow for an effective ignition can be different. This is precisely what leads to the fact that not all generators 8 along a line will trigger simultaneously and thus, if necessary, generators 8 will not be triggered at all, as described above.

(11) To avoid these non-triggered generators 8, a circuit 6 is proposed as it is explained by way of example in FIG. 2.

(12) In FIG. 2, circuit 6 is shown with an ignition means 10 inside a generator 8. The ignition means 10 for example has an ignition wire with a pyrotechnic charge. Circuit 6 can be connected via the connections 12a, 12b and 12c. Usually one of the circuits 6 is connected along a row as shown in FIG. 1 with the terminals 12a, 12c to control circuit 2, all other circuits 6 are connected with the terminals 12a, 12b to control circuit 2. Circuit 6 has a bypass circuit 6a and a circuit 6b for storing an ignition process. Circuit 6b is also called memory circuit 6b in the following.

(13) The bypass circuit 6a has a current mirror 14 which is connected asymmetrically to the terminals 12a, 12b via a resistor 16. On the output side of the current mirror 14, a thyristor or TRIAC 18 can be provided, which switches on at a sufficiently high voltage between cathode 18c and gate 18b and conductively connects the anode 18a with cathode 18c.

(14) In a monitoring mode, a measuring current of up to 5 mA is passed through the series connection as shown in FIG. 1. The measuring current flows from the connection 12a via the ignition means 10 to the connection 12b and from there to the next fire-fighting device 4. This is the normal operation mode in which no ignition has taken place yet. With the measuring current via the ignition means, the voltage drop across the ignition means caused by the current flow is so small that the current mirror does not receive its required minimum operating voltage and thus the thyristor 18 blocks.

(15) In case of a fire, the generators 8 should be ignited. For this purpose, an ignition current is applied to circuit 6 in case of a fire.

(16) The ignition current first flows through the ignition means 10, which causes the ignition wire in the ignition means 10 to heat up and finally leads to an activation of the pyrotechnic charge in the ignition means 10 and an activation of the generator 8 to discharge the aerosol.

(17) The moment the ignitor 10 is triggered, the electrical connection across the ignitor 10 may break and the ignitor 10 may block an electrical connection between terminals 12a, 12b. Due to the missing current flow through resistor 16, the asymmetrical connection of the current mirror 14 is reduced, so that the voltage between the collector of the current mirror 14 and the resistor 17 increases. This causes the ignition current to cause a sufficiently high voltage between the cathode 18c and the gate 18b of the thyristor 18 and to switch it on.

(18) The ignition current then flows, in spite of a disconnected line in the ignition means 10, through the thyristor 18 between the poles 12a and 12b. As a result, all fire-fighting devices 4 connected in series are permanently supplied with the ignition current as shown in FIG. 1, even if individual fire-fighting devices 4 or their ignition means 10 have already ignited and cause an electrical disconnection. Thus, the bypass circuit 6a ensures reliable operation of all generators 8 along a line of series-connected fire-fighting device 4 at one control circuit 2.

(19) At the moment of ignition, the wire in the ignition means 10 may break open. However, it is also possible that the wire fuses or an electrical connection through the means of ignition 10 remains after ignition in another way. In order to be able to monitor whether at least one means of ignition 10 of the fire-fighting device 4 has ignited along a line, a fire-fighting device 4 can be connected to the line according to FIG. 1 with the connections 12a and 12c.

(20) In such a case the memory circuit 6b is connected to the line. In the memory circuit 6b, a fuse 20 is provided which is designed to melt at an ignition current of a duration approximately or slightly shorter than the minimum duration for igniting an ignition means 10. In the case of the ignition current the fuse 20 melts and the Zener diode 22 becomes conductive due to the voltage drop across resistor 24 and breaks through. In this case, a sufficiently high voltage is applied between cathode 28c and gate 28b of thyristor 28 via resistor 27 and the thyristor 28 becomes conductive.

(21) This means that an ignition current can still flow via circuit 6 between terminals 12a and 12c, namely via thyristor 28, even if fuse 20 has melted.

(22) On the other hand, a measuring current is regularly introduced into the circuit to check whether it is still functional. If all ignition means 10 are still conductive, the measuring current flows via these ignition means 10. This can also be the case if an ignition means 10 has already ignited but an electrical connection has remained. In this case the measuring current would not be able to determine whether or not at least one fire-fighting device 4 has been ignited.

(23) Since a fire-fighting device 4 is connected in series via terminals 12a and 12c, the memory circuit 6b is also active. As already described, fuse 20 will melt in case of an ignition current. A measuring current then flows via resistor 24. This measuring current is too low, however, for the Zener diode 22 to become conductive and the thyristor 28 remains closed. This means that in case of a measurement via the series connection of the fire-fighting devices 4 along the line according to FIG. 1, a measuring current is routed at least via resistor 24. This causes a voltage drop between the poles 2a, 2b which can be measured and which from a certain magnitude indicates that the memory circuit 6b is activated and that the measuring current flows via resistor 24 and not via an intact fuse 20. This makes it possible to determine that the memory circuit 6b has been activated.

(24) With the help of the fire-fighting device according to the subject matter, it is possible to ensure a reliable ignition of fire-fighting devices connected in series at a control circuit.

LIST OF REFERENCE SIGNS

(25) 2 control circuit 2a, b poles 4 fire-fighting device 6 circuit 6a bypass circuit 6b memory circuit 8 generator 10 ignition means 12a-c connection 14 current mirror 16 resistance 17 resistance 18 thyristor 19 resistance 20 fuse 22 Zener diode 24, 26, 27 resistance 28 thyristor