EP0563340B1 - Fire-detecting device - Google Patents

Abstract

A fire-detecting device for ventilated appliances or machines (1) has a measurement chamber (2) through which flows the main current of cooling air or a representative fraction thereof, and at least one detector (12, 13) of a fire characteristic quantity arranged in the air flow within the measurement chamber (2) and connected for example by an electronic circuit to an alarm, extinguishing and/or switching off device. In order to shorten detection time and to increase the reliability of the fire detection in ventilated appliances or machines, for example EDP-appliances or similar electronic devices, the measurement chamber (2) is designed as a chimney whose cross-sectional opening lies on a partial cross section of the air outlet (6) of the ventilated appliance or machine (1). In an alternative embodiment, the measurement chamber (2) is designed as a flat box open on both sides ends and linked by its open frontal side to the outlet of an outgoing air channel (14) which is also designed as a box and lies on the air outlet (6) of the ventilated appliance (1).

Description

The invention relates to a device for detecting fires in ventilated devices or machines, for example in Computer equipment and similar electronic devices, with one from the main cooling air flow or a representative subset flowed through measuring chamber, and with at least one detector for recording a fire parameter, which in the measuring chamber in Airflow arranged and for example via an electronic Circuit with a warning, extinguishing and / or shutdown device connected is.

The invention further relates to a device of the aforementioned Type, which additionally has an exhaust air duct, which the Measuring chamber the main cooling air flow or the representative subset of it.

Such devices (see e.g. DE-A-3433459 and EP-A-459944) are for example also under the Technical term "home protection systems" known. Typical areas of application EDP systems are for facility protection systems and in particular individual components thereof and the like electronic devices, such as measuring, control and control systems, switching systems and private branch exchanges, CNC-controlled work machines and industrial robots, CAD / CAM systems or printers. It is known that the electronic assemblies of such devices or machines due their heat development is cooled, for example, by ventilation must be, depending on the type of ventilation either ventilated equipment is spoken at where the cooling air flow is generated by a fan in the device or naturally ventilated devices where a special arrangement of the devices at the installation site natural or artificial convection generated by air conditioners the indoor air is used.

The term "fire parameter" includes physical parameters understood that can be measured in the vicinity of an incipient fire Subject to change, e.g. the ambient temperature, the amount of solid or liquid or gas in the ambient air (Formation of smoke - particles or aerosols - or Steam) or the ambient radiation.

The importance of fire detection devices or, in short: facility protection systems takes parallel with the rapidly increasing Dependence on electronic data processing or on electronically controlled manufacturing processes in companies of any kind constantly. During fire protection measures still before tailored to preserving the building itself within a few years nowadays, an early and reliable one is required Fire detection directly on the devices or machines, to detect a fire as early as the development phase. The shortest possible time between the time of the Fire and the time of fire detection as well as the appropriate measures is for example at the beginning mentioned electronic devices in particular by of greatest importance, because with such facilities not the primary damage to the affected device is decisive is, but rather the secondary damage caused by a strong Smoke in the affected room. Come as a fire especially plastics such as PVC and polyethylene, for example as cable insulation, in question, when they burn hydrogen chloride gases become free, which in connection with the air humidity withdraw water to hydrochloric acid. This sets as a fine mist on the devices in the room or machines and penetrates them through the room air. The result is corrosion processes, the remediation of which often Failure of a complete system.

The problem with the early detection of fires in ventilated devices or machines or generally in the rooms where such devices are located in the ventilation the air circulation generated by the devices or the room, which is wanted with the goal of the best possible cooling. In air-conditioned rooms, such as in data centers, reach the air currents that are mostly directed from the bottom upwards the ceiling of the room not at all, so that there are often known point detectors found in the air flow contained smoke can be detected only very late. A Another point is that the main cooling air flow, for example change in a modular device can that the device is initially used with fewer bays and subsequently the cooling air distribution by adding additional inserts is changed significantly. One consequence of this is that the placement of the conventional point detectors afterwards is often no longer correct.

Recognizing this fact, the above mentioned were Fire detection devices developed, the measuring chamber directly is set up on the device to be monitored. These well-known Fire detection devices suck through, for example a fan from the main cooling air flow and lead this cooling air flow to the one located in the measuring chamber Detectors too. So that these known fire detection devices capture the main cooling air flow, they suck the Partial air on the air outlet openings of the ventilated Funnel or suction pipes attached to the device or the machine on. According to guidelines, it should be noted that the cooling air flow of the devices in question is not impaired.

The problem with these known fire detection devices is that due to the constantly changing device technology the air flow masses and also the flow velocities constantly increasing, which makes it more and more difficult a partial amount from the main cooling air flow of the ventilated device to tap and a reliable under good measuring conditions Detection of a fire parameter, especially the fire parameter "Solid or liquid content in the air" too enable. It is often the case that under the funnel or there is a large swirl of the cooling air in the measuring chamber, so that a detection of, for example, solid components in the cooling air (smoke) would take too long. The detection times with the known fire detection devices are about 60 seconds, and are still too long.

The present invention addresses this problem as its Task was considered to shorten the detection time as well as the reliability of the known fire detection devices to increase.

This object is achieved in a known device for detection of fires in ventilated devices or machines, for example in EDP devices and similar electronic devices, which is one of the main cooling air flow or a representative one Has a subset of flow-through measuring chamber and at least a detector for detecting a fire parameter, the arranged in the measuring chamber in the air flow and for example via an electronic circuit with a warning, extinguishing and / or shutdown device, according to the invention solved that the measuring chamber is designed as a chimney, the with a lower cross-sectional opening on a partial cross-section the air outlet of the ventilated device or machine is put on.

The "detection chimney" according to the invention provides one from the Furnace construction known pull that the swirled cooling air, the air outlet of the ventilated device or ventilated Machine leaves, calms down and enters a laminar flow of cooling air is transformed. This laminar flow of cooling air sweeps past the detector located in the detection chimney and thus enables extremely fast and reliable detection of solid or liquid components in the cooling air. With the fire detection device according to the invention Detection times of a few seconds can be achieved.

The advantages of the device according to the invention are furthermore especially in that the tapped from the main cooling air flow Partial air volume not through one for additional swirls the fan supplying the cooling air to the measuring chamber must be, but that the cooling air is exploited of the chimney effect known per se passed through the measuring chamber becomes. In addition, the fire detection device according to the invention with a smaller power supply unit gets along, since in addition to that for the detector or detectors Energy no additional energy for a fan is required.

Preferred developments for this solution according to the invention are specified in subclaims 2 to 7.

So it is different to adapt the detection chimney large air flow masses and also at different high flow velocities provided in an advantageous manner that the length of the chimney in the longitudinal direction of the one running through it Cooling air flow is changeable. With a large cooling air flow mass or at high flow velocities Length of the detection chimney increased until that in the detection chimney located detector laminar flow conditions are to be found.

According to the invention, there are two advantageous for this length adjustment Alternatives provided. According to a first solution the change in length through plug-in inserts, which either added or removed. According to one alternative solution is the detection chimney with a length manufactured that corresponds to the respective location.

It was explained at the outset that it is necessary to use a Fire detection device to detect the main cooling air flow. To ensure this more effectively, it is preferable provided that between the fireplace or the bottom insert and the air outlet of the ventilated device (s) Machine an exhaust air dome is arranged, the cross section of which expanded towards the air outlet. This cross-sectional expansion can particularly preferably in a Circular shape with which a particularly swirl-free Management of the cooling air flow is possible.

The fire detection device according to the invention is self-evident also on such ventilated devices or machines can be used in which the air outlet is arranged on the side. In this case, either the exhaust air dome or one of the plug-in inserts or the detection chimney itself for example, have a 90 ° curvature around the cooling air flow in the detection area as far as possible in the vertical direction cause, which further reduces the formation of turbulence becomes. For an angular detection chimney is to ensure a laminar flow in the detection area provided in an advantageous manner that the detector arranged in a linear section of the fireplace is.

The further support of a laminar cooling air flow serves an advantageous development of the invention, according to the cross-section of the chimney tapers in the direction of flow. As is known, this cross-sectional taper increases Flow rate, causing the formation of eddies counteracts or dissolves existing turbulence.

For the frequently occurring case that several ventilated devices or machines standing side by side is particularly advantageous Way provided that the chimney on an exhaust duct is attached, which is a subset of the main cooling air flow taps every ventilated device or machine and the lower cross-sectional opening of the fireplace - or else of the exhaust air dome - feeds.

The object underlying the invention is also in the previously described known device, which additionally a Exhaust air duct, which the measuring chamber the main cooling air flow or the representative subset thereof, according to the invention solved in that the measuring chamber as a flat, two-sided open box is formed with an open Is connected to the outlet of the exhaust air duct, that the exhaust air duct is also box-shaped and has a lid and attached side walls, and that the exhaust duct box with the open bottom on the air outlet of the ventilated device is attached.

The advantages of this solution according to the invention are in particular in the space-saving flat design of the exhaust air duct and the measuring chamber. This version of the fire detection device is therefore appropriate wherever above or on the Depending on the location of the device, the side to be secured ventilated device does not have as much space or the overall picture of the plant is not an upward one protruding measuring chamber should be disturbed. With this flat training the fire detection device becomes the desired laminar Cooling air flow already generated within the exhaust air duct, into which the cooling air flows in the exhaust duct and is moved towards the measuring chamber. This execution the fire detection device can also be used anywhere there, where the air outlet of the ventilated device has baffles, the cooling air flow emerging from the air outlet already at a certain angle to the plane of the air outlet, for example, deflect at 45 °. Thus the tapped flows Subset of the main cooling air flow also under the same Angle in the exhaust duct box, causing a backflow of the Cooling air by reflection on the underside of the cover of the exhaust duct box is avoided. Kick the tapped subset of the cooling air flow, for example, below 45 ° in the exhaust duct box one, the cooling air is at the bottom of the Cover deflected again by a further 45 ° and thus flows calmly towards the measuring chamber in the direction of flow.

Preferred developments for this solution according to the invention are specified in subclaims 10 to 13.

For all those ventilated devices whose air outlet, for example consists only of a simple grid, so that the emerging Cooling air perpendicular to the grille from the Device flows out, it is preferably provided that the exhaust duct box is formed in two parts by the lid and the Side walls form an upper part and a lower part is provided which has lamella-like air inlet slots in the bottom, whose lamellae are bevelled in the direction of flow are, and which can be inserted into the top from below is.

The slats can, for example, at an angle of 45 ° run to the bottom of the exhaust duct. The perpendicular from the Cooling air escaping from the ventilated device thus in the area of the fire detection device from the slats a first of the exhaust air duct in the direction of the measuring chamber Deflected times and on the underside of the cover of the exhaust air duct again, whereupon the tapped cooling air flow calms and turns into a laminar flow. As a result of that the tapped cooling air flow through the fins of the air inlet slots the exhaust duct box for the first time Direction of flow is deflected, a reflection of cooling air entering the exhaust air duct at the bottom the cover of the exhaust air duct avoided. This is in particular in the devices known from the prior art for tapping a partial quantity from a cooling air flow the problem. Meets the one coming out of the ventilated device Cooling air flow perpendicular to a tapping plate or the like, such as the underside of the cover of the exhaust air duct, so much of the tapped cooling air flow reflects and swirls, there is a build-up of cooling air, which is a transport of smoke particles, for example to the measuring chamber if not prevented.

Similar to the detection chimney mentioned above also the length of the exhaust air duct in the flow direction for adjustment to different sized air flows and also to different high flow rates in advantageous Modifiable by pluggable inserts. The whole Fire detection device can thus be constructed modularly, by - depending on the desired length of the overall device - one or several exhaust air duct units can be joined together the end of the exhaust air duct in the direction of flow Measuring chamber is connected.

Depending on the size of the flow rate from the vented Device leaking cooling air can be the distance of the fire detection device from the air outlet of the ventilated device according to an advantageous development of the invention Stands are changed to back up cooling air too avoid.

The following advantageous developments relate to both of the invention Solutions.

To increase interference immunity, i.e. to reduce the false alarm rate it is preferably provided that two detectors are arranged in the measuring chamber, the different Can address fire parameters. The two detectors will in a manner known per se in two lines to a fire alarm control panel switched. Depending on the requirement profile, the two can Detectors can be smoke detectors, gas detectors or heat detectors, where either both detectors, for example smoke detectors or but a smoke detector and another gas detector or Can be heat detectors. In addition, in the measuring chamber or but also a temperature sensor can be arranged in the exhaust air duct. Since in most cases with the development of fires with the Fire parameter "solid or liquid content in the Cooling air "is to be expected, for example the arrangement from two smoke detectors. Here come both optical Smoke detectors (O detectors) as well as ionization smoke detectors (1 detector) for use. Alternatively, can be tailored to the respective need - at least one of the two detectors designed as a gas detector or as a heat detector be. While a gas detector detects the fire parameter "Share of certain gases in the device cooling air" the heat detector reacts to heat radiation. The latter is to be used, for example, where the cooling air is unavoidable a certain proportion of solids, for example in the form of dust. Here would be a smoke alarm cause false alarms due to the dust. The heat detector can be designed as a maximum detector, which then responds, if the measured temperature is for a specified time certain threshold value, or as a differential detector, which responds when the rate of change of the measured temperature for a certain time Value exceeds, or both as maximum and Differential detector that combines both capabilities. The differential measurement in particular enables very early Display of abnormal temperature rises in the unit cooling air.

According to another advantageous development of the invention the two detectors face each other and in the direction of flow the measuring chamber is arranged offset from one another. The advantage the staggered and opposite arrangement One of the detectors is that the measuring chamber so gets by with a smaller cross-section and secondly in that the arrangement of the detectors in different Another height above the air outlet of the ventilated device makes a significant contribution to avoiding false alarms.

An advantageous alternative to the opposite one The arrangement of the detectors consists in the flow direction to be staggered, but on one Page. Then the detectors can namely on a common Circuit board can be arranged, which is a manufacturing technology Benefits and maintenance of the Fire detection device considerably facilitated, because only from one side requires access to the detectors for maintenance purposes is.

Fig. 1

eine Seitenansicht eines erfindungsgemäßen Detektionskamins mit Abluftdom und einem zwischen Kamin und Abluftdom gesteckten Einsatz;

Fig. 2

eine Draufsicht auf den Detektionskamin gemäß Fig. 1;

Fig. 3

eine Vorderansicht des Detektionskamins gemäß Fig. 1;

Fig. 4

die Anordnung des Detektionskamins gemäß den Figuren 1 bis 3 auf einem belüfteten Geräteschrank;

Fig. 5

die Anordnung eines Detektionskamins gemäß den Figuren 1 bis 3 seitlich an einem belüfteten Geräteschrank mit abgewinkeltem Abluftdom; und

Fig. 6

die Anordnung des Detektionskamins gemäß den Figuren 1 bis 3 auf einem Abluftkanal zum Schutz mehrerer belüfteter Geräte bzw. Maschinen.

Fig. 7

eine perspektivische Ansicht eines Abluftkanals als Bestandteil einer alternativen Ausführungsform einer Branderkennungsvorrichtung;

Fig. 8

eine Seitenansicht eines Einsatzes mit lamellenartigen Lüftungsschlitzen, der in den Abluftkanal gemäß Fig. 7 von unten einsetzbar ist;

Fig. 9

eine Draufsicht auf den Einsatz gemäß Fig. 8;

Fig. 10

eine perspektivische Ansicht des Abluftkanals gemäß Fig. 7 mit eingebautem Einsatz gemäß den Fig. 8 und 9;

Fig. 11

die Anordnung einer Branderkennungsvorrichtung mit zwei Abluftkanaleinheiten mit einer daran in Strömungsrichtung angeschlossenen Meßkammer auf dem Lüftungsgitter eines belüfteten Geräteschrankes;

Fig. 12

die Anordnung einer Abluftkanaleinheit auf dem Lüftungsgitter eines belüfteten Geräts, wobei der Abluftkanal mittels einer Zuleitung mit der Meßkammer verbunden ist;

Fig. 13

die Anordnung von zwei Abluftkanaleinheiten, die direkt an eine Meßkammer angeschlossen sind, seitlich an einem belüfteten Geräteschrank; und

Fig. 14

eine der Fig. 13 ähnliche Darstellung einer Branderkennungsvorrichtung seitlich an einem belüfteten Geräteschrank, wobei hier zwei Abluftkanaleinheiten über eine Zuleitung mit einer Meßkammer verbunden sind.

A preferred exemplary embodiment of the invention is explained in more detail below with reference to a drawing. Show it:

Fig. 1

a side view of a detection chimney according to the invention with exhaust air dome and an insert inserted between the chimney and exhaust air dome;

Fig. 2

a plan view of the detection chimney according to FIG. 1;

Fig. 3

a front view of the detection chimney according to FIG. 1;

Fig. 4

the arrangement of the detection chimney according to Figures 1 to 3 on a ventilated cabinet;

Fig. 5

the arrangement of a detection chimney according to Figures 1 to 3 laterally on a ventilated cabinet with angled exhaust dome; and

Fig. 6

the arrangement of the detection chimney according to Figures 1 to 3 on an exhaust air duct to protect several ventilated devices or machines.

Fig. 7

a perspective view of an exhaust duct as part of an alternative embodiment of a fire detection device;

Fig. 8

a side view of an insert with lamellar ventilation slots, which can be inserted into the exhaust air duct according to FIG 7 from below.

Fig. 9

a plan view of the insert of FIG. 8;

Fig. 10

a perspective view of the exhaust duct according to FIG 7 with built-in insert according to FIGS 8 and 9.

Fig. 11

the arrangement of a fire detection device with two exhaust duct units with a measuring chamber connected thereto in the flow direction on the ventilation grille of a ventilated equipment cabinet;

Fig. 12

the arrangement of an exhaust air duct unit on the ventilation grille of a ventilated device, the exhaust air duct being connected to the measuring chamber by means of a feed line;

Fig. 13

the arrangement of two exhaust duct units, which are connected directly to a measuring chamber, on the side of a ventilated equipment cabinet; and

Fig. 14

one of FIG. 13 similar representation of a fire detection device on the side of a ventilated equipment cabinet, here two exhaust air duct units are connected to a measuring chamber via a feed line.

Fig. 1 shows a side view of a device for recognition of fires in ventilated equipment or machinery that are essentially has a measuring chamber 2 which of the main cooling air flow or a representative subset tapped from it is flowed through, and furthermore two detectors 12, 13 in the form of smoke detectors, which in the measuring chamber 2 in the air flow flowing through them are arranged. The smoke detectors 12, 13 are not shown here electronic circuit with a warning, extinguishing and / or shutdown device connected, which is an optical and / or acoustic Display of a fire alarm as well as the immediate reaction with a deletion or by switching off the affected person Device.

The measuring chamber 2 is a chimney 4 (hereinafter also: detection chimney) trained, the length of which in the longitudinal direction of him continuous cooling air flow is changeable. A length adjustment of the fireplace 4 to the prevailing on site Ratios is required because both the air flow mass and the flow rate also varies from device to device is and therefore flow channels of different lengths 16 required to create a laminar flow region 17 are. Ultimately, however, even with modular devices the air flow conditions by adding or removing inserts change such that an adjustment of the length of the detection chimney is required to create a laminar flow to obtain.

In the embodiment shown in Fig. 1, the Length of the fireplace 4 through a plug-in insert 8 as well as additional enlarged by an exhaust dome 10. The cross section the exhaust dome 10 increases downwards and opens into a circular cross section 11. With this circular Cross section 11 shows the exhaust air dome 10 and thus the entire detection chimney 4 on the air outlet 6 of the ventilated device 1, which is no longer shown here. The from the air outlet 6 Cooling air escaping from the ventilated device passes through the lower cross-sectional opening 3 of the exhaust air dome 10 or the chimney 4 in the flow channel 16 and is on the two detectors 12, 13 passed. The two detectors 12, 13 are arranged opposite each other and offset in height, with both detectors projecting in their transverse extension, which increases the reliability of the fire detection device becomes.

2 shows a plan view of the detection chimney 4 This illustration shows that the exhaust air dome 10 expanded towards the bottom to a circular cross section 11, on the one hand, which means a larger proportion of the main cooling air flow and the stability of the entire device is increased.

3 shows a front view of the chimney-shaped measuring chamber 2 according to Figures 1 and 2. The change in length of the detection chimney 4 is of course also a telescopic Training of the fireplace 4 achievable.

Fig. 4 shows the detection chimney 4 with insert 8 and Exhaust dome 10 on the equipment cabinet 1 of a ventilated device. The circular expansion of the exhaust air dome 10 is mechanical Connections, such as screws 7, on the Air outlet 6 of the ventilated device attached. The cooling air of the ventilated device passes through the exhaust air dome 10 into the flow channel 16 of the measuring chamber 2, strokes as a laminar flow past the detectors 12, 13 and leaves the detection chimney 4 through its upper cross-sectional opening 5.

Fig. 5 shows a except for the formation of the exhaust air dome 10 identical to the fire detection device described above Embodiment. Here the detection chimney 4 is on the side air outlet slots 6 of a ventilated device 1 attached. The exhaust air dome 10 has a 90 ° curvature, so that the flow channel 16 within the detection chimney 4 runs in the vertical direction in the detection region 17. Also here the exhaust air dome 10 is circular in cross section at its end formed and by means of screws on the air outlet 6 attached.

6 shows the exemplary embodiment of the detection chimney according to FIG Figures 1 to 4 as a fire detection device for a Row of side-by-side ventilated devices 1, 1 ', 1 ", 1 "'. Here is the detection chimney 4 with the cross section circularly expanded exhaust air dome 10 onto an exhaust air duct 14 mounted, the 6, 6 ', 6 ", 6"' of the air outlets individual ventilated equipment cabinets via inlet openings 15 takes a subset of the main cooling air flow. The ventilated everyone Device removed cooling air flow is called common Air flow through the exhaust air dome 10 and the pluggable insert 8 fed to the detectors 12, 13. In this embodiment fire detection takes place for the merged Devices 1, 1 ', 1 ", 1"' together.

7 shows the perspective view of an exhaust air duct 14 - or an exhaust duct unit - as part of an alternative Embodiment of a fire detection device, its overall function are explained below with reference to FIGS. 11 to 14 becomes. One speaks of an exhaust air duct unit 14 in that than that shown in Fig. 7 front open air duct also with several almost identical exhaust duct units assembled into an exhaust duct of any length can be.

The exhaust air duct unit 14 shown in FIG. 7 is box-shaped formed and has a lid 25 and attached to it Side walls 26, 27 on. This exhaust duct box 14 is with the open bottom on the air outlet 6 of the ventilated Device 1 placed. If there is only one exhaust duct box in the Fire detection device is used, so one of the two End faces of the exhaust duct box 14 closed while the end face located in the flow direction of the cooling air flow the measuring chamber 2 is connected (see Fig. 11 to 14). Of the Exhaust duct box 14 shown in Fig. 7 is everywhere there can be used where the air outlet 6 of the ventilated device baffles 29 has, for example, the emerging cooling air flow at an angle of 45 ° to the plane of the air outlet let out (Fig. 13 and 14).

Fig. 8 shows a side view of a lower part 23 with lamella-like Air inlet slots 18, which in the upper part 22 of the exhaust duct 14 according to FIG. 7 used from below can be. The lower part 23 has here, for example End wall 28 for closing off the exhaust air duct 14 on, but this is not necessary if the exhaust duct box 14, i.e. with upper part 22 and lower part 23 as the middle one Unit is installed in a longer exhaust air duct. In like this In one case, of course, both ends are open, to let the cooling air flow through. The slat-like Air inlet slots 18 of the lower part 23 each have an edge running across the direction of flow, fins 24 on that at an angle of about 45 ° to the bottom plate of the lower part 23 beveled in the direction of flow. These slats serve essentially perpendicular to the floor panel of the lower part 23 entering through the air inlet slots 18 Redirecting cooling air in the direction of flow for the first time, to ensure a perpendicular impact of the air flowing into the exhaust air duct 14 Cooling air on the underside of the cover 25 (Fig. 7) to avoid, which results in a backlog of cooling air would have. Such a backlog affects the function the fire detection device, since the transport of the recognizing smoke particles or liquid components in the cooling air to measuring chamber 2 no longer or only with large temporal Delays occur. On the other hand, there is a backwater of cooling air from the manufacturer of the device to be monitored and also undesirable on the part of the operator, since undesirable Overheating of components can result.

FIG. 9 shows a top view of the lower part 23 according to FIG. 8, from which the position of the slats 24 becomes clear again.

Fig. 10 shows an assembled from upper part 22 and lower part 23 Exhaust duct box 14. This exhaust duct box 14 is resulted from the fact that the lower part 23 according to FIGS. 8 and 9 was inserted from below into the upper part 22 according to FIG. 7. Of the Exhaust duct box 14 is on one end face with an end wall 28 closed. Thus, this exhaust duct box 14 a unit as it is within a longer one, from several Exhaust duct units 14 composite exhaust duct as left-justified unit or as the only exhaust duct unit 14 is used. Will the exhaust duct box 14 as a middle unit to form a longer exhaust duct inserted, the end wall 28 is omitted clearly that the length of the entire exhaust duct by compilation several exhaust duct units, which are also different May have lengths, i.e. modular, changeable is. This length adjustment advantageously takes place an adaptation of the fire detection device to the dimensions of the device to be monitored and it can be optimized the length of the exhaust air duct is particularly efficient for a laminar one The cooling air flows in the exhaust air duct to the measuring chamber.

To further reduce the risk of an air backlog the exhaust duct box 14 on its side walls 26, 27 protruding downward beyond the bottom plate of the insert 23 Stand strips 30, 31, whereby the air inlet slots of the Exhaust duct box 14 from the air outlet 6 of the ventilated device are spaced. The height of these stand strips - or also the stand 20 according to FIG. 11 - the flow rate adapted to the cooling air flowing out of the ventilated device will.

11 to 14 are some use variants of the flat Embodiment of the fire detection device according to the invention explained. 11 and 12 are each for use in such a ventilated equipment cabinet 1, whose air outlet 6 in the form of a simple grid the top of the equipment cabinet 1 is attached, from which the Cooling air thus rises essentially vertically. On the Air outlet grille 6 of the equipment cabinet 1 according to FIG. 11 two exhaust duct units 14 in the flow direction with one Measuring chamber 2 arranged coupled. The two exhaust duct units 14 essentially correspond to that shown in FIG. 10 Exhaust duct unit 14 with the difference that at the stator strips shown in FIG. 11 30, 31 are replaced by transverse columns 20. The vertically emerging from the air outlet 6 of the equipment cabinet 1 Cooling air flows in the area below the exhaust duct units 14 into this through the air inlet slots 18 and is thereby for the first time through the slats 24 An angle of approximately 45 ° in the direction of flow towards the measuring chamber 2 distracted. The second deflection of the cooling air takes place on the Underside of the cover 25 of the exhaust duct units 14 (cf. Fig. 7). Thus, the tapped ones are deflected overall Partial amount of the main cooling air flow by 90 °, whereby - depending on Outflow speed of the cooling air from the ventilated device 1 - by choosing an appropriate length of the entire exhaust duct ensure that within the exhaust duct units 14 A laminar flow of cooling air is created. Without that redirection the cooling air entering the exhaust air duct units 14 through the fins 24, the cooling air would be perpendicular to the Bottom of the cover 25 of the exhaust duct units encounter what would result in a backlog. Through the double redirection the cooling air within the exhaust air duct and by appropriate Adjustment of the length of the exhaust air duct ensures, however, that the tapped part of the main cooling air flow as laminar Flow enters the measuring chamber 2, where the cooling air to the sweeps past both detectors 12, 13 and on the end face 19 of the measuring chamber 2 can emerge again.

12 is the use of a further embodiment of the Fire detection device on the same ventilated equipment cabinet 1 shown. Here, too, the cooling air essentially occurs vertically from the air outlet 6 of the ventilated device 1 out. However, in contrast to the ventilated cabinet, there is a flow 1 of FIG. 11 the cooling air here with such a low flow rate that a measuring chamber 2 for use comes that by means of its own fan via a supply line 21 from the exhaust air duct box 14 the tapped part the cooling air is actively extracted. This is also known from DE-A-3433459. With such low flow speeds can also be disregarded the exhaust duct by stand 20 (see FIG. 11) or by protruding stand strips 30, 31 (see FIG. 10) from the air outlet grille to be spaced apart. Only at exhaust air speeds of about> 2 m per second there is no active suction and a fire detection device according to FIG. 11 is used will.

13 and 14 each show a ventilated equipment cabinet 1, where the cooling air is already below a certain Angle emerges from the air outlet 6 of the ventilated device 1. The cooling air is deflected here through the device cabinet side already existing air baffles 29 in the two In the cases shown, deflect the cooling air downwards by about 45 °. The fire detection device exists in both cases 13 and 14 from two exhaust duct units 14, which here however consist only of the upper parts 22 according to FIG. 7, and each from a measuring chamber 2. Since that from the air outlet 6 of the ventilated device 1 already exiting cooling air the baffles 29 deflected in the flow direction into the exhaust air duct 14 occurs, is a use of the lower part 23 according to 8 and 9 are not required in the present case. The already entering obliquely downward into the exhaust air duct 14 Cooling air is on the underside of the cover 25 of the exhaust duct units 14 deflected once more in the direction of flow, so that here again a laminar flow of cooling air in the direction of the measuring chamber 2.

Corresponding to the differences between FIGS. 11 and 12 also comes with the equipment cabinets of FIGS. 13 and 14, respectively a different measuring chamber 2 for use. With the ventilated Device 1 of FIG. 13 is a device in which the cooling air from the air outlet 6 at a flow rate emerges that is greater than about 2 m per second is. Thus, an active extraction of the cooling air from the Exhaust duct can be dispensed with because of the self-flow rate the cooling air is sufficient, the tapped part of the To transport cooling air through the exhaust air duct to the measuring chamber 2.

The device cabinet 1 shown in FIG. 14 is concerned is a ventilated device whose cooling air flow rate when leaving the air outlet 6 is not sufficient, for safe transport of the tapped amount of cooling air to ensure through the exhaust duct 14 to the measuring chamber 2. Therefore, the measuring chamber 2 has a fan here, with which the tapped cooling air from a supply line 21 extracted from the exhaust air duct 14 and the detectors in the measuring chamber 2 is supplied. This is also known from DE-A-3433459.

Claims (15)

1. A device for detecting fire in ventilated appliances or machines, such as electronic data processing equipment and similar electronic means, comprising a measuring chamber through which flows the main current of cooling air or a representative fraction thereof and further comprising at least one detector arranged in the measuring chamber in the air flow for sensing a fire characteristic magnitude and connected to an alarm means, an extinguishing and/or a switch-off device, for example by way of an electronic circuit, characterized in that the measuring chamber (2) is designed as a chimney (4) having a lower cross sectional opening (3) which is placed at least on a part cross section of an air outlet (6) of the ventilated appliance or ventilated machine (1), whereby the measuring chamber (2) is shaped or designable in such a way that the flow conditions at the detector (12, 13) located in the measuring chamber (2) are laminar.
2. The fire-detecting device as claimed in claim 1, characterized in that the length of the chimney (4) is variable in the direction of flow of the current of cooling air passing through the same.
3. The fire-detecting device as claimed in claim 2, characterized in that the variation in length of the chimney (4) is effected by plug-in inserts (8).
4. The fire-detecting device as claimed in any one of claims 1 to 3, characterized in that an exhaust air dome (10) whose cross section widens towards the air outlet (6) is arranged between the chimney (4) or the lowest insert (8) and the air outlet (6) of the ventilated appliance or ventilated machine (1).
5. The fire-detecting device as claimed in any one of the claims 1 to 4, characterized in that the detector (12) is arranged in a section of the chimney (4) taking a linear course.
6. The fire-detecting device as claimed in any one of the claims 1 to 5, characterized in that the cross section of the chimney (4) converges in the direction of flow.
7. The fire-detecting device as claimed in any one of the claims 1 to 6 for a plurality of ventilated appliances or machines located closely adjacent to one another, characterized in that the chimney (4) is placed upon an exhaust channel (14) which taps a fraction of the main current of cooling air of each ventilated appliance and passes it to the lower cross sectional opening (3) of the chimney (4).
8. A device for detecting fire in ventilated appliances or machines, such as electronic data processing equipment and similar electronic means, comprising a measuring chamber through which flows the main current of cooling air or a representative fraction thereof, at least one detector arranged in the measuring chamber in the air flow for sensing a fire characteristic magnitude and connected to an alarm means, an extinguishing and/or a switch-off device, for example by way of an electronic circuit, and further comprising an exhaust air channel which supplies the main current of cooling air or the representative fraction thereof to the measuring chamber, characterized in that the measuring chamber (2) is designed as a flat box, open at two sides, having one open face end connected to the outlet of the exhaust air channel (14), in that the exhaust air channel (14) likewise is of box-shaped design and includes a cover (25) with sidewalls (26, 27) attached to it, and in that the exhaust air channel box (14) is placed with ist open bottom on the air outlet (6) of the ventilated appliance (1), whereby the measuring chamber (2) is shaped or designable in such a way that the flow conditions at the detector (12, 13) located in the measuring chamber (2) are laminar.
9. The fire-detecting device as claimed in claim 8, characterized in that the exhaust air channel box (14) is of two-part design, the cover (25) and the sidewalls (26, 27) constituting an upper part (22), and a lower part (18) in its bottom, the fins (24) thereof being of inclined design in the direction of flow, which lower part is adapted to be inserted from below into the upper part (22).
10. The fire-detecting device as claimed in claim 8 or 9, characterized in that the length of the exhaust air channel (14) is variable by plug-in inserts in the direction of flow of the current of cooling air passing through the same.
11. The fire-detecting device as claimed in one of claims 9 or 10, characterized in that the air inlet slots (18) are disposed spaced from the air outlet (6) of the ventilated appliance (1) by means of brackets (20).
12. The fire-detecting device as claimed in any one of the preceding claims, characterized in that two detectors (12, 13) are arranged in the measuring chamber (2) which are adapted to respond to different fire characteristic magnitudes.
13. The fire-detecting device as claimed in claim 12,
    characterized in that the two detectors (12, 13) are located opposite each other and offset with respect to each other in the direction of flow of the measuring chamber (2).
14. The fire-detecting device as claimed in claim 12,
    characterized in that the two detectors (12, 13) are located on the same side and offset with respect to each other in the direction of flow of the measuring chamber (2).
15. Method for detecting fire in ventilated appliances or machines, such as electronic data processing equipment and similar electronic means, comprising a measuring chamber through which flows the main current of cooling air or a representative fraction thereof and further comprising at least one detector arranged in the measuring chamber in the air flow for sensing a fire characteristic magnitude and connected to an alarm means, an extinguishing and/or a switch-off device, for example by way of an electronic circuit, characterized in that the measuring chamber (2) is adapted in shape and length to the current of cooling air in such a way that laminar flow conditions are generated in the measuring chamber.

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