DE202013012395U1 - Device for cleaning an optical entrance window - Google Patents

Abstract

Device for cleaning an optical entrance window (1) of a fire detector (2), comprising - at least one gas outlet opening (7) for discharging a gas stream onto the surface of the optical entrance window (1) of the fire detector (2), - a control unit (3), and - A valve (4), wherein the control unit (3) signal-conducting connected to the valve (4) and adapted to selectively switch the valve (4) in an open or closed position, wherein the valve (4) fluid-conducting, preferably by means of a pressure line (6) to which at least one gas outlet opening (7) is connected, wherein the control unit (3) is arranged to control the valve (4) such that an intermittent gas flow from the at least one gas outlet opening (7) to the Surface of the optical entrance window (1) of the fire detector (2) with a number of pressure pulses (14) on the optical entrance window (1) is applied, wherein a plurality of pressure pulses (1 4) form a series of pressure pulses (15) with a time (t2) between two pressure pulses (14), and wherein a valve (4) is provided for discharging the gas flow from the gas outlet opening (7), the valve (4) being formed as follows Switching steps: - switching the valve (4) to an open position for the duration (t1) of a pressure pulse (14), - switching the valve (4) to a closed position for the time (t2) between two pressure pulses (14), wherein these switching steps are performed by a control unit (3) by sending corresponding control signals from the control unit (3) to the valve (4).

Description

The invention relates to a method for cleaning an optical entrance window of a fire detector and a device for cleaning an optical entrance window.

The invention is applicable everywhere where optical entrance windows of fire detectors must remain permeable to the fire characteristics or must be cleaned at predetermined intervals cleaning the disc.

The term of the optical entrance window is understood to mean an entrance window made of a material which adequately transmits the fire parameter, namely in the form of electromagnetic radiation, for the detection of fire characteristics in the interior of the fire detector to sensor elements. The optical entrance window may be permeable to infrared radiation, visible light, and / or UV radiation, depending on the sensor means used inside the fire detector. Sometimes, the optical entrance window is therefore also referred to as a viewing window, although it does not have to be transparent in all cases.

Optical entrance windows of fire detectors provide only a perfect function, if they can get through these signals to sensor elements. In an environment in which dust particles or powder are present as suspended matter in the ambient air, it frequently happens that the optical entrance window of the fire detector is contaminated by dirt or powder deposits, so that fire signals reach the sensor of the fire detector insufficiently or incorrectly. It is therefore necessary to keep the optical entrance window always clear of contamination or contamination.

In order to monitor the degree of contamination of optical entrance windows, the person skilled in various ways are known. As a rule, radiation is sent to the optical entrance window and the reflected radiation passing through the optical entrance window is sensory measured and compared.

In DE 42 40 395 C2 . US 5,914,489 A or US 4,728,794 These methods and the corresponding devices are described.

In order to ensure that the optical entrance windows are kept free of surface or dirt, fire detectors with air purifiers have been developed which, on the one hand, permanently build up an air cushion in front of the window to prevent deposits of process substances. On the other hand, pressure washers are known to clean the viewing window at regular intervals. In addition, the cleaning can also be done mechanically.

All of these known ways of cleaning the optical entrance window of a fire detector can not prevent deposits or powders with certain properties in the surroundings of the fire detector from being deposited on the optical entrance window which can not be removed with conventional pressure-flushing devices or an air cushion. In the case of optical entrance windows, which are provided with a protective grid, no mechanical cleaning is possible without problems, unless the protective grid is removed manually and the optical entrance windows are mechanically cleaned.

All the above devices and methods describe ways to clean the optical entrance window of a fire detector with a continuous stream of air or gas stream.

Due to the continuous air consumption relatively low pressures are used. Nonetheless, the consumption of such installations adds up to substantial levels over the period of one year, especially in the case of systems with several fire detectors with air flushing. Compressed air is considered one of the most expensive sources of energy, so that the operator often incurs high costs. Nevertheless, the cleaning effect of the known prior art devices is often insufficient.

EP 2 381 430 B1 describes a method and a device for cleaning an optical entrance window of a fire detector, wherein a pulsating gas flow is passed over the surface of the optical entrance window, in which a rhythmically escaping or pulsating gas flow is created by pressure building up between an elastic lip and the optical entrance window and the pulsating gas stream escapes by striking the elastic lip on the optical entrance window.

Also by this method, a lot of compressed air is consumed as escaping at regular, non-controllable intervals compressed air. Furthermore, compressed air always reaches the optical entrance window only horizontally. Due to the fact that the elasticity of the lip changes over a long period of time, leaks may occur, so that the cleaning effect deteriorates or in the case of a defect completely disappears.

The intermittent application of a gas or compressed air flow to the optical entrance window of the fire detector with selectable pressure pulse duration and pressure pulse sequence as well as different and very high intensity is not possible with this device.

Based on this prior art, it is therefore an object of the invention to develop a method and a device with which the optical entrance window of a fire detector is kept free of dust particles with little effort and at the same time reliably and intermittently.

This object is achieved by a device according to the features of claim 1.

Subclaims give advantageous embodiments of the invention again.

• – Abgeben eines intermittierenden Gasstroms aus zumindest einer Gasaustrittsöffnung (7) auf die Oberfläche des optischen Eintrittsfensters (1) des Brandmelders (2), wobei
• – der intermittierende Gasstrom mit einer Anzahl von Druckimpulsen (14) auf das optische Eintrittsfenster (1) ausgebracht wird.

The method according to the invention comprises the following steps:

• - dispensing an intermittent gas stream from at least one gas outlet opening ( 7 ) on the surface of the optical entrance window ( 1 ) of the fire detector ( 2 ), in which
• The intermittent gas flow with a number of pressure pulses ( 14 ) on the optical entrance window ( 1 ) is applied.

In other words, the intermittent gas flow from the gas outlet opening is guided over the surface of the optical entrance window of the fire detector. It is thus an intensive intermittent gas flow with preferably a plurality of pressure pulses, each with a short time t ₁ applied to the optical entrance window, wherein a plurality of pressure pulses form a pressure pulse train with a time t ₂ between two pressure pulses and between the pressure pulse series a pause time t ₃ .

The inventive method for cleaning an optical entrance window of a fire detector provides an intermittent gas flow, which acts at predetermined time intervals with high intensity and short exposure time on the surface of the optical entrance window. The intermittent gas flow is realized by pressure pulses. The pressure pulses are preferably generated by switching a valve which is arranged in a pressure line which connects a gas supply system, preferably a compressed air system, with the at least one gas outlet opening and closes or closes this connection by switching the valve.

The time intervals and the exposure time of the pressure pulses are preferably predetermined by a control unit, such as a fire alarm and / or extinguishing control center and their software or by another control center. These specifications can be made depending on the pollution.

The control unit preferably sends control signals to the valve to switch opening and closing of the valve. These are, for example, voltage or current signals, depending on the selected valve type.

For the provision of the intermittent gas flow gas is used from a gas delivery system which delivers the gas at a desired pressure via respective pressure lines from the gas delivery system to the at least one gas exit port. In an advantageous embodiment, the gas supply system is a compressed air system and the gas is then preferably compressed air.

• – Schalten des Ventils in eine geöffnete Stellung für die Zeitdauer eines Druckimpulses,
• – Schalten des Ventils in eine geschlossene Stellung für die Zeit zwischen zwei Druckimpulsen, und für die Pausenzeit zwischen zwei Druckimpulsserien, wobei diese Schaltschritte von einer Steuereinheit mittels Senden von korrespondierenden Steuersignalen von der Steuereinheit an das Ventil ausgeführt werden.

The invention is preferably further developed in that a plurality of pressure pulses form a pressure pulse series with a time between two pressure pulses and there is a pause between the pressure pulse series, and wherein a valve is provided for emitting the gas flow from the gas outlet opening, the method further comprising the steps:

• Switching the valve to an open position for the duration of a pressure pulse,
• Switching of the valve in a closed position for the time between two pressure pulses, and for the pause time between two pressure pulse series, wherein these switching steps are performed by a control unit by sending corresponding control signals from the control unit to the valve.

The term "corresponding control signals" means a corresponding control signal for switching the valve to an open position or to a closed position of the valve. In the open position of the valve, the gas stream under pressure, released in the direction of the gas outlet opening, is interrupted in the closed position.

The intermittent gas stream is preferably discharged or applied to the optical entrance window in a plurality of short pressure pulses at high pressure and high speed via one or more gas outlet openings. By "high" pressure is meant a pressure of up to 30 bar. Between two successive pressure pulses within a pressure pulse train is preferably a time without pressure pulse. This time is called time t ₂ between two pressure pulses. The time duration t ₁ in which the pressure pulse acts and the time t ₂ between two pressure pulses are predetermined according to the application and can be approximately the same, for example.

There is a pause time t ₃ between two pressure pulse series. This break time carries a lot essential for lowering energy consumption or gas consumption.

The time duration t _{1 of} a pressure pulse, the time t ₂ between two pressure pulses and the pause time t ₃ between two pressure pulse series are preferably realized by sending control signals of a control unit to a valve. Preferably, a solenoid valve or a pneumatic valve or other valve is used.

In a further preferred embodiment, the time duration t _{1 of} a pressure pulse, the time t ₂ between two pressure pulses and the pause time t ₃ between two pressure pulse series is realized by a pneumatic control.

It is advantageous if the time duration t _{1 of} the pressure pulse is 10 milliseconds to 5 seconds. Particularly advantageous is a time of 0.5 seconds.

Furthermore, it is advantageous if the time t ₂ between two pressure pulses is 10 milliseconds to 5 seconds. Particularly advantageous is a time of 0.5 seconds.

It is advantageous if the number of successive pressure pulses of a pressure pulse series is 1 to 200 pressure pulses. Particularly advantageous are four successive pressure pulses. In an alternative embodiment of the method, 1 to 100 pressure pulses are advantageous.

• – Überwachen eines Verschmutzungsgrads des optischen Eintrittsfensters mittels eines Überwachungsmittels,
• – Übertragen eines repräsentativen Signals an die Steuereinheit, sobald ein vorbestimmter Grenzwert des Verschmutzungsgrades überschritten wird, und
• – Schalten des Ventils zur Abgabe des intermittierenden Gasstroms, vorzugsweise über eine Druckleitung und die Gasaustrittsöffnung auf das optische Eintrittsfenster so lange, bis der Verschmutzungsgrad die vorgegebene Grenze nicht mehr überschreitet.

The pause time t ₃ between two pressure pulse series is preferably 2 seconds to 60 minutes. Particularly preferably, the pause time t _{3 is} one minute. In a particularly preferred embodiment of the method according to the invention, the method further comprises the steps:

• Monitoring a degree of soiling of the optical entrance window by means of a monitoring means,
• - Transmitting a representative signal to the control unit as soon as a predetermined limit of the degree of contamination is exceeded, and
• - Switching the valve to deliver the intermittent gas flow, preferably via a pressure line and the gas outlet opening on the optical entrance window until the degree of contamination does not exceed the predetermined limit.

In other words, the control of the valve for releasing the gas flow, for generating the pressure pulses, the pressure pulse series and the number of pressure pulses in the pressure pulse series by the control unit in dependence on the degree of contamination of the optical entrance window.

The degree of contamination is preferably determined by a monitoring means. When a predetermined limit of a limit value of the degree of contamination is exceeded, the monitoring means sends a representative signal to the control unit. This signal is preferably sent from the monitoring means, or from the fire detector itself to the control unit. In an advantageous embodiment, the control unit also detects the presence of a state in which the degree of contamination does not exceed (exceeds) a predetermined limit value. In this case, the purging of the optical entrance window with the intermittent gas flow is reduced or interrupted.

• – Fortgesetztes Zuführen des intermittierenden Gasstroms für eine vorbestimmte Nachspüldauer, vorzugsweise in einem Bereich von 1 Sekunde bis 10 Minuten, und
• – Schalten des Ventils in die geschlossene Stellung nach Ende der Nachspüldauer.

Preferably, the method is developed such that after detection by the monitoring means that the contamination no longer exceeds or falls below the predetermined limit value, the step is carried out:

• Continued feeding of the intermittent gas flow for a predetermined Nachspüldauer, preferably in a range of 1 second to 10 minutes, and
• - Switching the valve to the closed position after the end of the rinsing time.

About the control signals of the control unit, which are sent to the valve, the pressure pulses described above and the pressure pulse train with the times t ₁ , t ₂ and t _{3 are} realized. Instead of a solenoid valve and another valve, for example, a pneumatically adjusting valve, conceivable.

The gas supply system is designed so that the necessary pressure of the pressure pulses is available. The pressure of the pressure pulse is in an advantageous embodiment in a range between 1 to 30 bar, in a further advantageous embodiment, it is in a range between 2 and 10 bar. In a particularly advantageous embodiment, a pressure of 5 bar is used.

As mentioned above, the device in a further aspect also relates to a device for cleaning the optical entrance window of a fire detector.

The invention solves the underlying task in such a device by comprising at least one gas outlet opening for dispensing a gas flow to the surface of the optical entrance window of the fire detector, a control unit, and a valve, wherein the control unit is signal-conducting connected to the valve and adapted thereto to selectively switch the valve to an open or closed position, the Valve fluid-conducting, preferably by means of a pressure line, is connected to the at least one gas outlet opening, wherein the control unit is adapted to control the valve such that an intermittent gas flow from the at least one gas outlet opening on the surface of the optical entrance window of the fire detector with a number of pressure pulses is applied to the optical entrance window.

The gas outlet opening is preferably fluid-conductively connected by means of a pressure line to a gas supply system, from which compressed air is supplied to the gas outlet opening at times predetermined by the control unit (t ₁ , t ₂ , t ₃ ).

The control unit is preferably configured to switch the valve according to the method described above.

The gas stream may contain one or more gases. Preferably, compressed air, which is a gas mixture, is used. The gas supply system generates the necessary pressure of the gas stream. By opening and closing the valve via the control of the control unit, the flow of the gas stream from the gas supply system is released to the at least one gas outlet opening and pressure pulses of the gas stream and pressure pulse series are generated with a predefined number of pressure pulses.

The at least one gas outlet opening is arranged on a gas discharge means.

The gas discharge means has the at least one gas outlet opening for discharging a gas flow onto the surface of the optical entrance window of the fire detector. Furthermore, at least one connection of the pressure line is arranged on the gas discharge means which is fluid-conductively connected to the at least one gas inlet channel which opens into the at least one gas outlet opening. In an advantageous embodiment, the gas application means is a nozzle or a diffuser.

In advantageous embodiments, in which 2, 3 or 4 gas outlet openings are arranged, a corresponding number of nozzles or diffusers are arranged and the gas stream is passed directly to the optical entrance window.

The gas discharge means is adapted to apply an intermittent gas flow from the at least one gas outlet opening to the surface of the optical entrance window of the fire detector with a number of pressure pulses on the optical entrance window.

In the preferred embodiment of the device, the gas discharge means on three gas inlet channels, which open into three gas outlet openings. In this case, three connections for the pressure line are arranged on the gas discharge means, which are fluid-conductively connected to the gas inlet channels.

In an advantageous embodiment of the device, the gas application means is arranged interchangeably on the housing of the fire detector via connecting means. In another embodiment, the gas application means is integrated in the housing of the fire detector.

In a further advantageous embodiment, the gas stream or compressed air exits from one, the optical entrance window, circumferential opening. This is adapted to the geometric shape of the entrance window. For example, it is advantageous for a circular entrance window to use a ring-shaped outlet gap as a gas outlet opening.

In an advantageous embodiment, the gas application means for distributing the gas flow to the optical entrance window, attached to the housing of the fire detector and referred to as an attachment. This gas application means has at least one connection for the connection to the pressure line, which feeds the gas stream, preferably the compressed air from the gas supply system, preferably to a compressed air system. Particularly advantageous are 3 connections, so that a uniform distribution of the gas flow or the compressed air, which is passed from the gas outlet openings on the optical entrance window, is achieved.

Particularly advantageous is the circular arrangement of the 3 gas outlet openings at a distance of 120 °.

In a further advantageous embodiment, a gas flow distribution means is arranged between the direct path of the gas stream from the terminal of the attachment part and the optical entrance window, which is arranged to distribute the gas flow evenly, since in the region of the gas outlet opening a maximum of the pressure value of the gas stream is present.

In a further advantageous embodiment of the fire detector is connected to the attachment part via connecting elements so that it can be connected by quick assembly with a simple rotational movement with the attachment part or removed.

The annular gap opening has in a further advantageous embodiment at certain points of the Circumference of the optical entrance window constrictions in order to generate a targeted pressure increase in these areas.

Furthermore, the control unit is arranged, which communicates with a valve such as a solenoid valve, or an electrically releasable valve or the pneumatic valve. Corresponding lines, such as electrical lines, are preferably provided for the signal-conducting connection between the control unit and the valve. Alternatively or additionally, the control unit is adapted to switch the valve by means of excitation of pneumatic control lines or by wireless data transmission, for example by radio, depending on the selected valve type.

The valve is preferably located in the pressure line which is connectable to or part of a gas delivery system. The gas delivery system is preferably a compressed air system. In a preferred embodiment, upstream of the valve, a compressed gas reservoir is arranged and fluidly connected to the valve. In other words, the compressed gas storage is then arranged between the gas supply system and the valve.

Preferably, another valve, a shut-off valve, is arranged between the compressed gas reservoir and the gas supply system. This valve serves as a shut-off option when working on the system, furthermore, the air supply can be reduced during the pause time t ₃ between two pressure pulse series in order not to burden the gas supply system with pressure surges.

In a particular embodiment, the shut-off valve is designed as a solenoid valve and connected to the electronic control unit.

The compressed gas storage may be formed as one or more compressed gas cylinder (s). From this compressed gas cylinder, the pressurized gas can be passed to the time specified by the control unit or time intervals to the gas outlet opening and emerge from this.

With the gas supply system, the compressed gas storage can be recharged again and again. This can be done advantageously in the time between the pressure pulse series. If this charge occurs at a reduced flow rate, the compressed gas storage has the advantage that the gas delivery system is not burdened with the pressure pulses.

In a particularly preferred embodiment of the device according to the invention, the control of the valve to release the gas flow via at least one gas outlet opening via the optical entrance window by the control unit in dependence on the degree of contamination of the optical entrance window. In this embodiment, the control unit is set up to switch the valve as a function of the degree of soiling of the optical entrance window.

For this purpose, the device for cleaning the optical entrance window preferably has a monitoring means for monitoring the degree of soiling of the optical entrance window, which is signal-conducting connected to the control unit and adapted to transmit a representative signal to the control unit when a predetermined limit of the degree of contamination is exceeded Control unit is adapted to switch on receipt of the representative signal, the valve for delivering the intermittent gas flow.

In a further advantageous embodiment of the device, this has a monitoring means for monitoring the degree of soiling of the optical entrance window, which is signal-conducting connected to the control unit and adapted to transmit a representative signal to the control unit when exceeding a predetermined limit of the degree of contamination. In this case, the control unit is set up to switch the valve for emitting the intermittent gas flow upon receipt of the representative signal, until the degree of contamination no longer exceeds the predetermined limit value or lies within a predefined permissible range.

The monitoring means, which may be formed as a sensor monitoring system or may be part of such a system, is preferably adapted to measure the degree of soiling of the optical entrance window. A preferred monitoring means comprises means for irradiating the optical entrance window with electromagnetic radiation at a predetermined wavelength, preferably ultraviolet (UV) and / or infrared (IR) radiation sources, and means for quantitatively detecting that portion of the radiation which differs from is reflected to the optical, and / or means for quantitatively detecting that portion of the radiation which passes through the optical entrance window, and / or means for quantitatively detecting that portion of the radiation which is absorbed upon impact with the optical entrance window.

The means for quantitatively detecting the proportion of the reflected, transmitted or absorbed radiation are preferably radiation sensors for detecting electromagnetic radiation in the ultraviolet (UV) and / or in the infrared (IR) range. Area. Furthermore, these means comprise a signal processing unit. This includes a microcontroller or a microprocessor, A / D and D / A converters and memory elements, as well as means for signal transmission to the control unit via a signal-conducting connection between the monitoring means and the control unit. In the memory elements, the predefined limit value of the degree of contamination of the optical entrance window and / or a predefined permissible range are stored.

In a preferred embodiment, these radiation sensors represent the radiation sensors of the fire detector for detecting the fire characteristic. In this case, the monitoring means is simultaneously a sensor monitoring system. In a further preferred embodiment, the signal processing unit of the monitoring means is the signal processing unit of the fire detector. In this case, the signal-conducting connection between the monitoring means and the control unit is the signal-conducting connection between the fire detector and the control unit.

The monitoring means is configured to use this quantitative detection to determine a representative numerical value as to how much radiation is reflected or absorbed in comparison to a previously determined unpolluted state and to compare this with the predetermined limit value. Upon reaching or exceeding this limit value, the monitoring means then transmits the representative signal to the control unit.

In a further advantageous embodiment of the device according to the invention, which is particularly advantageous for use when the fire detector has no suitable sensor monitoring system for monitoring the degree of contamination of the optical entrance window of the fire detector, the control unit is adapted to the valve for emitting the intermittent gas flow, in particular for Generation of the pressure pulses of the gas flow to switch at pre-defined times. These switching times may be periodic or aperiodic depending on the environmental conditions. The control unit is preferably pre-programmed with these times or programmable via an input device with these times.

It is also advantageous if before and after (upstream and downstream of) the pressure gas storage a pressure gauge and a valve are arranged. As a pressure gauge, a pressure gauge is suitable.

Furthermore, preferably upstream of the valve, more preferably between compressed gas storage and gas supply system, a pressure reducer is arranged, with which the operating pressure for the compressed gas storage can be adjusted.

In a preferred embodiment, the gas supply system comprises a compressor, for example an electric compressor, which is adapted to fill the compressed gas storage with gas.

The inventive method and apparatus have the advantage that the optical entrance window of a fire detector can be freed intermittently and according to the pollution intensity with a customized and low consumption of gas from contamination.

Through a gas jet, which impinges on the optical entrance window of the fire detector at high speed, vortexes form, so that soiling on the entire surface is detected and washed away with high intensity.

In the following the invention will be explained in more detail with reference to a preferred embodiment with reference to the accompanying figures. The figures show:

1 : Apparatus for cleaning an optical entrance window in a schematic representation, and

2 : Schematic representation of pressure pulses over time.

The 1 shows schematically a device according to the invention for cleaning an optical entrance window 1 a fire alarm 2 by means of a gas outlet opening 7 in a gas release agent 8th , The gas release agent 8th is so above the optical entrance window 1 attached so that its circular recess comprises the optical entrance window. The circular recess is dimensioned such that the viewing angle of the sensors (not shown) of the fire detector 2 for detecting the fire parameter electromagnetic radiation is not reduced. This viewing angle is essentially determined by the diameter of the effectively acting optical entrance window, the sensitive area of the sensors and the distance between the sensors and the optical entrance window.

The gas release agent 8th has two gas outlet openings 7 for dispensing a gas flow onto the surface of the optical entrance window 1 the fire detector 2 on. Not shown are the two connections of the pressure line 6 at the Gas discharge means which are fluid-conductively connected to the respective gas inlet channel, and in the gas outlet openings 7 lead.

The gas release agent 8th is adapted to an intermittent gas flow from the gas outlet openings 7 on the surface of the optical entrance window 1 the fire detector 2 with a number of pressure pulses 14 on the optical entrance window 1 deploy.

But it can also be several gas outlet openings 7 in the gas application agent 8th be provided, for example, 2, 3, 4, or more.

The gas outlet openings 7 in the gas application agent 8th are fluid-conducting via a fluid-conducting gas inlet channel with a connection, not shown, for the pressure line 6 at the gas application means 8th connected, thus also fluid-conducting with this pressure line 6 connected. In this illustrated embodiment, the pressure line 6 designed as a compressed air line.

The compressed air is supplied by a gas delivery system 9 delivered, with which the gas outlet openings 7 fluid-conducting via the pressure line 6 and a valve 4 are connected. Thus, the valve 4 fluid-conducting, preferably by means of the pressure line 6 , with the gas outlet openings 7 connected. In the switching position of the valve 4 "On" the compressed air flow to the gas outlet openings 7 released, for discharging a gas flow from this gas outlet opening to the surface of the optical entrance window 1 ,

In the 1 illustrated inventive device further comprises a control unit 3 , and the valve 4 , wherein the control unit 3 signal-conducting with the valve 4 connected and set up the valve 4 optionally to switch to an open or closed position. Here is the control unit 3 to set up the valve 4 such that an intermittent gas flow from the gas outlet opening 7 on the surface of the optical entrance window 1 the fire detector 2 with a number of pressure pulses 14 ( 2 ) on the optical entrance window 1 is applied.

The valve 4 is executed in the illustrated embodiment as a solenoid valve, which by the control unit 3 , designed in this case as a fire alarm and / or extinguishing control center, is controlled via the signal-conducting connection. This fire alarm and / or extinguishing control unit realizes the switching of the valve and in an open switching position for the time t _{1 of} the pressure pulses 14 , in a closed switching position for a time t ₂ between the pressure pulses 14 and for the pause time t ₃ between the pressure pulse series 15 and the frequency of driving to generate the number of pressure pulses 14 within a pressure impulse series 15 through their software and / or hardware.

The compressed gas storage 5 is over the pressure line 6 with a gas delivery system 9 , formed as a compressed air system, connected, from the compressed air, in the pause time t ₃ between two pressure pulse series 15 , into the compressed gas storage 5 , can flow. Before and after the compressed gas storage 5 are the valve 4 and the shut-off valve 16 and manometer 10 arranged, over electrical lines 12 with the control unit 3 can be connected. This makes it possible the valve 4 and the shut-off valve 16 depending on the measured pressure. The shut-off valve is a manual valve in the example shown and not by a line to the control unit 3 connected.

Between the gas supply system 9 and the valve 4 is a pressure reducer 13 arranged, with which the operating pressure for the compressed gas storage 5 can be adjusted.

The fire detector 2 has a monitoring means 11 on that with the control unit 3 via a signal-conducting connection 17 connected is. This signal-conducting connection 17 can be realized via electrical lines or wirelessly, for example by radio.

Not shown is another preferred embodiment of the device that the signal processing of the sensor monitoring system or monitoring means of the electronic circuit of the fire detector 2 is carried out. In this case, the signaling connection 17 the signaling connection of the fire alarm with the control unit.

About the signaling connection 17 sends the monitoring device 11 a representative signal to the control unit 3 , which is a measure of the pollution of the optical entrance window 1 is. This measure may be predetermined as a limit or represent a quantitative or relative instantaneous value. If the optical entrance window gets dirty 1 beyond a certain level, for example when a predetermined limit value is exceeded, the control unit triggers 3 via their implemented software by sending control signals to the valve 4 , specifically an intermittent gas flow with pressure pulses 14 , preferably in several pressure pulse series 15 , with times t ₁ , t ₂ and t ₃ ( 2 ). In the illustrated embodiment, this is done until the sensor monitoring system 11 no longer detects any inadmissible pollution, ie the degree of contamination lies within a predefined permissible range.

Alternatively or additionally, the control unit triggers 3 on the basis of a predetermined, preferably programmatically in the control unit 3 stored time schedule the pressure pulses 14 and pressure pulse series 15 for a given period of time. This allows cleaning even without detection of a certain degree of contamination by means of the monitoring means 11 and ensures the cleaning function even in cases where the monitoring means 11 does not work or there is no monitoring means. The 2 shows a schematic representation of an extract of several pressure pulse series 15 using the example of 2 pressure pulse series 15 which each contain 4 pressure pulses. The time duration t _{1 of} the pressure pulses is shown 14 on a timeline. pressure pulses 14 represent the pressure with which the compressed air in one through the control unit 3 given time on the gas outlet openings 7 on the optical entrance window 1 acts.

Several pressure pulses 14 form a series of pressure impulses 15 , In 2 are exemplary two pressure pulse series 15 shown. Every pressure pulse 14 lasts for a given time t ₁ , that is, at the first pressure pulse 14 The compressed air acts on the entrance window for about 0.5 seconds 1 , This is followed by a time t ₂ between the compressed air pulses 14 in which no compressed air on the entrance window 1 acts. In the case shown, t ₂ = t ₁ = 0.5 s. In 1 are four pressure pulses 14 and its duration t ₁ and three times t ₂ between the pressure pulses 14 shown. These pressure pulses 14 form a series of pressure impulses 15 ,

After the pressure pulse series 15 , which lasts 3.5 seconds, follows the pause time t ₃ between the pressure pulse series 15 , This is 10 minutes in the illustration. This is followed by another series of pressure pulses 15 ,

Of course, the invention is also for fire detectors 2 applicable, which is not a monitoring device 11 for detecting the degree of soiling of the entrance window 1 exhibit. In this case, the control of the valve takes place 4 through the control unit 3 at predefined times and with a given frequency and duration adapted to the environmental conditions of the pollution cause.

If the pollution intensity due to environmental influences or the like changes fundamentally, programming the control unit 3 the parameters of time t ₁ , t ₂ and t ₃ or / and the frequency of the pressure pulses are adjusted.

LIST OF REFERENCE NUMBERS

1

optical entrance window

2

fire alarm

3

control unit

4

Valve

5

Compressed gas storage

6

pressure line

7

Gas outlet

8th

Gas output means

9

Gas supply system,

10

manometer

11

monitoring means

12

electrical line

13

pressure reducer

14

pressure pulse

15

Pressure pulse series

16

shut-off valve

17

signal-conducting connection

t ₁

Duration of a pressure pulse 14

t ₂

Duration between two pressure pulses 14

t ₃

Pause time between two pressure pulse series 15

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 4240395 C2 [0006]
• US 5914489 A [0006]
• US 4728794 [0006]
• EP 2381430 B1 [0011]

Claims (7)

Device for cleaning an optical entrance window ( 1 ) of a fire detector ( 2 ), comprising - at least one gas outlet opening ( 7 ) for discharging a gas flow onto the surface of the optical entrance window (US Pat. 1 ) of the fire detector ( 2 ), - a control unit ( 3 ), and - a valve ( 4 ), the control unit ( 3 ) signal-conducting with the valve ( 4 ) and is adapted to the valve ( 4 ) optionally in an open or closed position, wherein the valve ( 4 ) fluid-conducting, preferably by means of a pressure line ( 6 ), with the at least one gas outlet opening ( 7 ), the control unit ( 3 ) is adapted to the valve ( 4 ) such that an intermittent gas flow from the at least one gas outlet opening ( 7 ) on the surface of the optical entrance window ( 1 ) of the fire detector ( 2 ) with a number of pressure pulses ( 14 ) on the optical entrance window ( 1 ), whereby several pressure pulses ( 14 ) a pressure pulse series ( 15 ) with a time (t ₂ ) between two pressure pulses ( 14 ), and wherein for discharging the gas flow from the gas outlet opening ( 7 ) a valve ( 4 ) is provided, wherein the valve ( 4 ) is designed to perform the following switching steps: - switching the valve ( 4 ) in an open position for the duration (t ₁ ) of a pressure pulse ( 14 ), - switching the valve ( 4 ) in a closed position for the time (t ₂ ) between two pressure pulses ( 14 ), these switching steps being performed by a control unit ( 3 ) by sending corresponding control signals from the control unit ( 3 ) to the valve ( 4 ). Apparatus according to claim 1, wherein between the pressure pulse series ( 15 ) has a break time (t ₃ ) and the control unit ( 3 ) is formed by sending corresponding control signals from the control unit ( 3 ) to the valve ( 4 ), the valve ( 4 ) to switch to a closed position for the pause time (t ₃ ) between two pressure pulse series. Apparatus according to claim 1 or 2 with a signal-conducting with the control unit ( 3 ) ( 11 ), which is adapted to the degree of contamination of the optical entrance window ( 1 ) and send a representative signal to the control unit ( 3 ) as soon as a predetermined limit of the degree of contamination is exceeded, and wherein the control unit is adapted to the valve ( 4 ) to deliver the intermittent gas flow as soon as the control unit ( 3 ) receives the representative signal. Device according to claim 1, characterized in that it comprises a monitoring means ( 11 ) for monitoring the degree of soiling of the optical entrance window ( 1 ), which signal-conducting with the control unit ( 3 ) and is arranged to send a representative signal to the control unit ( 3 ) when exceeding a predetermined limit of pollution level, the control unit ( 3 ) is arranged, upon receipt of the representative signal, the valve ( 4 ) to deliver the intermittent gas flow, until the degree of contamination does not exceed the predetermined limit value or lies in a predefined allowable range. Device according to one of claims 1 to 4, characterized in that upstream of the valve ( 4 ) a compressed gas storage ( 5 ) and fluid-conducting with the valve ( 4 ) connected is. Device according to one of claims 1 to 5, characterized in that upstream of the valve ( 4 ) a pressure reducer ( 13 ) is arranged, with which the operating pressure for the compressed gas storage ( 5 ) can be adjusted. Device according to one of claims 1 to 6, characterized in that the control unit ( 3 ) is adapted to the valve ( 4 ) to switch depending on the degree of contamination of the optical entrance window.

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