fire alarm system

Abstract

Fire alarm device (1) with at least one fire gas detector (5) for detecting fire gases, wherein the at least one fire gas detector (5) comprises a light emitter (5a) for emitting light radiation and a light receiver (5b) for receiving the light radiation, with an absorption measurement section (A) that runs from the light emitter (5a) to the light receiver (5b), wherein the combustion gases can be detected by the light receiver (5b) depending on the light intensity of the light radiation received by the light receiver (5b), with a plurality of deflection sections (9) for deflecting the light radiation along the absorption measurement section (A), wherein the absorption measurement section (A) runs in a spiral and / or helical shape, wherein the deflection sections (9) comprise a curved surface such that the deflection sections (9) are focusing or defocusing.

Description

State of the art

[0001] The invention relates to a fire alarm device with at least one fire gas detector for detecting fire gases, wherein the at least one fire gas detector comprises a light emitter for emitting light radiation and a light receiver for receiving the light radiation, with an absorption measuring section that runs along the light radiation from the light emitter to the light receiver, wherein the fire gases can be detected by the light receiver depending on the light intensity of the light radiation received by the light receiver, with a plurality of deflection sections arranged in the absorption measuring section for deflecting the light radiation.

[0002] Automatic fire alarm systems are commonly used for the early detection of fires in public or private premises. Such fire alarm systems typically include at least one fire sensor, which can detect a fire in its vicinity at an early stage and trigger an alarm based on fire-specific parameters such as smoke, soot particles, temperature, or gas concentrations.

[0003] German patent application DE 25 04 300 A1 discloses a transmission detector with at least one electromagnetic radiation source, the radiation of which passes through the medium under investigation and strikes at least one photoelectric receiver, and an electrical circuit for signal output when the receiver irradiation changes, characterized by several reflection points and at least two different beam paths from the transmitter to the receiver, which pass over the same reflection points in different sequences with the same number of reflections, but with different total path lengths, and by a device for evaluating the different radiation attenuation caused by suspended particles and / or gas components in the medium in the individual beam paths.

[0004] A gas sensor is known from DE 60 2004 008 562 T2. The gas sensor comprises an optical source, a detector, and an optical path extending between the source and the detector.

[0005] DE 10 2007 006 153 A1 discloses an optical gas sensor arrangement for detecting at least one analyte in a sample gas. The gas sensor arrangement comprises a radiation source for emitting radiation with a specified intensity, a detector device, and a reaction path for guiding the radiation, which is designed such that the intensity of the emitted radiation can be changed by interaction with the sample gas depending on the presence of the analyte. Disclosure of the invention

[0006] The invention discloses a fire alarm device with the features of claim 1. Preferred or advantageous embodiments of the invention are described in the dependent claims, the following description, and the accompanying figures.

[0007] The invention relates to a fire detection device that can be mounted, for example, on a wall or ceiling to detect a fire in buildings, such as in corridors or rooms. The fire detection device is preferably a ceiling-mounted detector, particularly a surface-mounted detector, or a wall-mounted detector. Optionally, the fire detection device can also be integrated into and / or include a ceiling light. A maximum diameter of less than 20 centimeters, particularly less than 10 centimeters, and especially less than 5 centimeters, is particularly preferred. In particular, the fire detection device is a component of an alarm system and can be connected to one or more fire detection devices and / or a fire alarm control panel. Alternatively, the fire detection device is designed as a standalone fire detector, particularly preferably with an integrated and / or independent power supply.Optionally, the fire alarm system includes a siren for issuing an audible fire warning.

[0008] The fire alarm device comprises at least one fire gas detector for detecting fire gases, particularly preferably NO and / or NO2. Fire gases are produced as a result of fires, so their detection allows for the conclusion that a fire has occurred. Preferably, the fire gas detector is arranged in a housing of the fire alarm device.

[0009] The at least one fire gas detector comprises a light emitter for emitting light radiation and a light receiver for receiving the light radiation. Each fire gas exhibits at least one specific absorption band, with nitrogen oxides such as NO and NO₂, for example, exhibiting an absorption band in the wavelength range of UV radiation or an absorption band in the visible range. Against this background, it is particularly preferred that the light emitter be a UV LED. However, depending on the fire gases to be detected, an infrared LED or a blue LED, which can also detect NO₂, is also possible. In particular, the light receiver is a sensor, most preferably a photodiode, for measuring the light radiation, specifically for measuring only a wavelength range of the light radiation emitted by the light receiver. In this way, the measurement of interfering radiation is excluded or at least reduced.Preferably, the fire alarm device includes a circuit for generating a sensor signal based on the measured light radiation from the light receiver.

[0010] The fire alarm system includes an absorption sensor that runs along the path of light radiation from the light emitter to the light receiver. The detection of combustion gases depends on the light intensity received by the light receiver. A decrease in light intensity occurs when the light radiation is absorbed by combustion gases. If the light receiver receives a light intensity lower than a reference light intensity, this indicates the presence of combustion gases in the air within the absorption sensor. Specifically, the light intensity is measured according to Lambert-Beer's law, which describes the attenuation of light intensity with increasing path length as it passes through an absorbing substance.

[0011] Preferably, the fire alarm device includes an evaluation unit for detecting the fire based on the sensor signal. For example, the fire is detected when the measured light intensity falls below a predefined threshold during absorption measurement. The use of an additional reference light source is particularly advantageous; this light source emits electromagnetic radiation of a wavelength or wavelength range at which the fire gases to be measured exhibit no or only minimal absorption.

[0012] The installation space of a fire alarm device is limited, meaning that with direct light emission from the light emitter to the receiver, an arbitrarily long absorption measurement path cannot be selected. For this reason, the fire alarm device includes multiple deflection sections arranged within the absorption measurement path to redirect the emitted light radiation to the light receiver. Specifically, the light radiation strikes the deflection section and is deflected to another deflection section or to the light receiver. Multiple deflection sections are understood to mean, for example, at least three, in particular at least five, and specifically at least ten deflection sections. In particular, the multiple deflection sections allow for an extension of the absorption measurement path while maintaining the same installation space.In this way, the sensitivity of the light radiation to be measured can be increased so that even the smallest concentration levels, such as ppb (parts per billion), can be distinguished. It is preferably provided that the deflection sections are opaque. Deflection mirrors or sections thereof are particularly preferred.

[0013] Within the scope of the invention, it is proposed that the absorption measurement path has a spiral path. Thus, the light beam is deflected from the light emitter to the light receiver, in particular in a spiral and / or helical manner. The term "spiral" refers in particular to a helical path of the absorption measurement path with increasing or decreasing distance from a center point or axis. The term "helical" refers in particular to a helical path with a constant or varying pitch and a constant or varying diameter, especially around any imaginary support body, such as a straight cylinder, a cone, or a cone.

[0014] The spiral and / or helical design, compared to an opposing arrangement of the light emitter and receiver, allows for a longer absorption measurement path, thus eliminating the need to increase the distance between the light emitter and receiver and the associated increase in the circumference of the fire alarm device. This results in a space-saving arrangement of the deflection sections within the fire alarm device.

[0015] It is particularly preferred that the deflection sections are arranged spirally and / or helically relative to one another. A spiral arrangement refers in particular to the arrangement of the deflection sections in a helical path with increasing or decreasing distance from the center point or axis. A helical arrangement refers in particular to the arrangement of the deflection sections in a helical path. In this way, the spiral and / or helical path of the absorption measurement section is implemented.

[0016] In a first particularly preferred embodiment, the absorption measurement section is arranged in a plane. Thus, the absorption measurement section has a central point. Advantageously, the two-dimensional, spiral shape, with its increasing and decreasing distance to the central point, allows for a particularly compact design by utilizing the space available in this plane.

[0017] In a second particularly preferred embodiment, the absorption measuring section runs in a three-dimensional path, wherein the three-dimensional path is helical and optionally additionally spiral-shaped. Preferably, the three-dimensional path is helical, particularly helix-shaped. Thus, the absorption measuring section has, in particular, an axis. Preferably, the deflection sections are arranged at different heights along the axis. Compared to a two-dimensional path, the three-dimensional helical path allows for the use of multiple deflection sections, so that a longer absorption measuring section can be achieved if required. For example, the helical path of the absorption measuring section has a constant slope. For example, the axis of the absorption measuring section is aligned with, parallel to, or configured as the main longitudinal axis of the fire alarm device.

[0018] In preferred embodiments, the absorption measurement section can lie in a plane and form a spiral path, in particular designed as an Archimedean spiral, a logarithmic spiral, a hyperbolic spiral or even a Fermat spiral.

[0019] Alternatively, the absorption measurement section can be formed as a three-dimensional, helical path, whereby the pitch of the helical path can be variable or constant.

[0020] In this configuration, the absorption measurement section, e.g. as a helix and / or as a straight screw, is designed with a constant or with a varying pitch.

[0021] As a further alternative, the absorption measurement section can be designed as a three-dimensional path in a spiral and helical shape, wherein the pitch of the winding of the absorption measurement section is variable or constant, and the absorption measurement section is spiral in plan view, in particular as an Archimedean spiral, a logarithmic spiral, a hyperbolic spiral or even a Fermat spiral.

[0022] In the other alternative, the absorption measuring section can be designed as a cone-shaped, in particular conical, screw.

[0023] In terms of design, it is preferred that the light emitter is arranged radially outside the center or axis of the spiral and optionally helical path of the absorption measurement section, and the light receiver is arranged radially inside, or vice versa. This allows the light beam to travel in a spiral and / or helical path from the light emitter, through the deflection sections, to the light receiver. Furthermore, it is preferred that the light receiver is located in the center of the absorption measurement section.

[0024] In one possible embodiment of the invention, the absorption measurement section has at least one 360° rotation, in particular at least one 720° rotation, and specifically at least one 1080° rotation. In this way, the enlargement of the absorption measurement section is achieved without, or at least with minimal, additional space requirements compared to the opposite arrangement of the light emitter and receiver.

[0025] Due to its spiral shape, the absorption measurement section from the light emitter to the light receiver has a decreasing or increasing diameter towards an open end, particularly towards the light emitter or receiver. A preferred embodiment of the invention provides that the fire alarm device, starting from the beginning of the absorption measurement section, particularly from the light emitter, comprises at least a first, a second, and a third deflection section, wherein a first measurement absorption section is formed between the first and second deflection sections, and a second measurement absorption section is formed between the second and third deflection sections. In particular, the second measurement absorption section is at most ten percent, and specifically at most five percent, shorter (in the case of decreasing diameter) or longer (in the case of increasing diameter) than the first measurement absorption section.Optionally, additional deflection sections can be provided downstream, between which the measurement absorption section is reduced or lengthened by a maximum of ten percent. The smaller the difference in length between the measurement absorption sections, the more deflection sections can be arranged, and consequently, the longer the absorption measurement path can be.

[0026] In a further preferred embodiment of the invention, the deflection angle between two adjacent deflection sections is at least 30°, in particular at least 50°, and specifically at least 100° and / or at most 175°. It is particularly preferred that an increasing deflection angle is selected as the number of deflection sections increases, so that the difference between the adjacent measurement absorption sections is kept small. Thus, an increasing number of deflection sections can be arranged as the deflection angle increases.

[0027] For example, the deflection sections, in particular the deflection mirrors, are identical in construction. Alternatively, it can be provided that the deflection sections, in particular the deflection mirrors, have different sizes and / or reflection properties. According to the invention, the deflection sections comprise curved surfaces. Furthermore, according to the invention, the deflection sections are focusing, or alternatively, defocusing.

[0028] A preferred design embodiment provides that the deflection sections each comprise a metal layer. The metal layer preferably enables the deflection of light in the visible wavelength range, particularly from 390 nm to 790 nm, and thus proves advantageous for light emitted by the light emitter in this wavelength range. Alternatively or optionally, the deflection sections can each comprise a dielectric layer. The dielectric layer preferably enables the deflection of light in the ultraviolet wavelength range, particularly from 150 nm to 390 nm, and thus proves advantageous over metallic layers for light emitted by the light emitter in this wavelength range. Alternatively, particularly for wavelengths below 250 nm, a metallic layer, such as aluminum or an aluminum alloy, can be used.The metallic layers are generally not or only slightly wavelength-selective, so they can be used at various wavelengths. In another possible design, the deflection sections each comprise a multilayer layer that enables the deflection of light in the EUV (extreme ultraviolet) wavelength range, particularly from 10 nm to 121 nm, and thus proves advantageous for light emitted by the light emitter in this wavelength range.

[0029] As previously described, the majority of deflection sections aim to improve the differentiation between concentration levels by increasing the distance between the light emitter and receiver. However, an excessive number of deflection sections leads to a reduction in the base intensity of the emitted light beam. Therefore, it is preferred that the fire alarm device has a maximum of 50, particularly a maximum of 30, and specifically a maximum of 20 deflection sections. This number of deflection sections, together with the spiral and / or helical shape of the absorption measurement path, achieves an optimal balance between space utilization and measurement accuracy.

[0030] It is particularly preferred that the light emitter, receiver and deflecting mirrors are arranged in a measuring room, so that optical shielding from the surroundings of the fire alarm device and thus the measurement of ambient light is excluded.

[0031] Further features, advantages, and effects of the invention will become apparent from the following description of preferred embodiments of the invention and the accompanying figures. These show: Fig. 1 in a schematic representation a fire alarm device with a fire gas detector; Fig. 2 in a top view an absorption measurement section of a fire gas detector as a first embodiment of the invention; Fig. 3 in top view the absorption measuring section of the fire gas detector as a second embodiment of the invention; Fig. 4 in the top view the absorption measuring section of the fire gas detector as a third embodiment of the invention; Fig. 5 in the top view the absorption measuring section of the fire gas detector as a fourth embodiment of the invention; Fig. 6. The absorption measurement path follows a spiral shape in a plane; Fig. 7 the spiral shape of the absorption measurement path in a helical shape.

[0032] Corresponding or identical parts are each provided with the same reference symbols in the figures.

[0033] Fig. Figure 1 shows a fire detection device 1, which can be mounted, for example, on a wall or ceiling to detect a fire in buildings, e.g., in corridors or rooms of the building. For example, the fire detection device 1 is a ceiling-mounted detector such as a surface-mounted detector or a wall-mounted detector. For example, the fire detection device 1 includes at least one alarm device for issuing an alarm signal upon detection of a fire. Alternatively or optionally, the fire detection device 1 includes an interface via which an alarm signal for fire detection can be output, e.g., to a fire alarm control panel.

[0034] The fire alarm device 1 comprises a housing 3 with a measuring chamber 4. The housing 3 has a maximum circumference of at most 100 cm. A fire gas detector 5 is arranged in the measuring chamber 4. The fire gas detector 5 serves to detect fire gases and has a light emitter 5a for emitting light radiation and a light receiver 5b for receiving the light radiation. The fire alarm device 1 includes an absorption measuring section A, which runs along the light radiation from the light emitter 5a to the light receiver 5b.

[0035] The combustion gases can be detected by the light receiver 5b depending on the light intensity of the radiation received by the light receiver 5b. Each combustion gas has a specific absorption band, with nitrogen oxides such as NO and NO₂, for example, exhibiting an absorption band in the wavelength range of UV radiation. The light intensity of the UV radiation incident on the light receiver 5b is therefore dependent on the nitrogen oxides present along the absorption measurement path A, since these absorb at least a portion of the wavelength range of UV radiation. Thus, the light emitter 5a is, for example, a UV LED and the light receiver 5b is a photodiode. The detection of a decreasing light intensity provides an early indication of nitrogen oxides, which in turn suggests a fire.

[0036] The light receiver 5b generates a sensor signal based on the received light radiation. The fire alarm device 1 includes an evaluation unit 6 (see Fig. 2), which detects the fire based on the sensor signal of the light receiver 5b. Optionally, fire detection can be carried out taking into account an additional sensor signal generated based on the light radiation from a reference light source received by the light receiver 5b or another light receiver.

[0037] Optionally, the fire alarm device can have 1 additional sensors that detect fire-specific characteristics. A CO sensor 7 and a temperature sensor 8 are shown here as examples.

[0038] The fire alarm device 1 comprises a plurality, in particular at least five, deflection sections 9 arranged in the absorption measuring section A for deflecting the emitted light radiation from the light emitter 5a to the light receiver 5b. The plurality of deflection sections 9 allows for an extension of the absorption measuring section A compared to an opposite arrangement of the light emitter 5a and receiver 5b. For example, the deflection sections 9 are deflection mirrors or sections thereof.

[0039] For example, the deflection sections 9 are identical in construction and / or exhibit the same reflective properties. For instance, the deflection sections 9 comprise curved and / or planar surfaces with defocusing or focusing properties. The deflection sections 9 each have, for example, a metallic and / or dielectric layer designed to deflect light rays in the UV range. This enables the determination of nitrogen oxides, which, among other things, absorb electromagnetic radiation in the UV wavelength range.

[0040] The Fig. Figure 2 shows a top view of the absorption measurement section A with the deflection sections 9. The absorption measurement section A is spiral-shaped. Specifically, the absorption measurement section A forms exactly one continuous spiral. The spiral can be a prototypical spiral, an Archimedean spiral, a logarithmic spiral, or a hyperbolic spiral. For example, the spiral shape of the absorption measurement section A comprises at least one complete turn, and in particular, at least one complete coil. The spiral shape is, in particular, a helical shape of the absorption measurement section A with increasing distance from a center point M or an axis L. The spiral shape achieves, on the one hand, the lengthening of the absorption measurement section A and thus improved differentiation between concentration levels.On the other hand, the available installation space is used optimally, so that an increased space requirement and the associated enlargement of the housing 3 are at least largely avoided.

[0041] The deflection sections 9 are arranged spirally relative to each other, thus enabling the spiral path of the absorption measurement section A. The light emitter 5a is arranged radially outside the center point M or axis L of the spiral path of the absorption measurement section A, and the light receiver 5b is arranged radially inside. In this embodiment, the evaluation unit 6 is located in the center of the absorption measurement section A. Alternatively, to further extend the absorption measurement section A, the light receiver 5b can be arranged in the center of the absorption measurement section A.

[0042] The spiral shape of the absorption measurement section A results in a diameter that decreases, particularly continuously, towards an open end, i.e., towards the light emitter or receiver 5a, 5b. This decreasing diameter can occur for each individual turn, or alternatively, within each individual turn. In this embodiment, the diameter decreases from the light emitter 5a towards the light receiver 5b.

[0043] The fire alarm device 1 comprises a first, a second, a third, and further deflection sections 9a, 9b, 9c. A first measuring absorption section A1 is formed between the first and second deflection sections 9a, 9b, and a second measuring absorption section A2 is formed between the second and third deflection sections 9b, 9c. The second measuring absorption section A2 is shorter than the first measuring absorption section A1, so that the decreasing diameter is implemented in the direction of the open end, here in the direction of the light receiver 5b. For example, the second measuring absorption section A2 is at most ten percent shorter than the first measuring absorption section A1. The smaller the difference between the measuring absorption sections A(n) and A(n+1), the more the decrease in the diameter of the spiral path slows down. In this way, more deflection sections 9 can be arranged.

[0044] For example, a deflection angle α between two adjacent deflection sections is at least 30° and / or at most 175°. With an increasing number of deflection sections 9, an increasing deflection angle α must be selected to keep the difference between the adjacent measurement absorption sections A1, A2, etc., or A(n), A(n+1), small. Consequently, with an increasing deflection angle α, an increasing number of deflection sections 9 can be arranged.

[0045] The Fig. 3, Fig. 4 to Fig. Figure 5 schematically shows further embodiments of the absorption measurement section A in a top view. As can be seen from the Fig. 3, Fig. 4 to Fig. As can be seen in Figure 5, the magnitude of the deflection angle Alpha increases with an increasing number of deflection sections 9. Furthermore, the difference between the adjacent measurement absorption sections A1 and A2 decreases with an increasing number of deflection sections 9. The absorption measurement section A in the top view shows a symmetrical, spiral shape, although an asymmetrical shape is also possible.

[0046] Fig. Figure 6 shows a first advantageous embodiment of the absorption measuring section A in a side view. The absorption measuring section A is arranged in a plane E. Thus, the spiral of the absorption measuring section A is, in particular, a two-dimensional spiral. Due to its arrangement in the plane E, the absorption measuring section A has a center point M. The deflection sections 9 are arranged, for example, in the same plane for the two-dimensional, spiral path of the absorption measuring section A. The two-dimensional, spiral path of the absorption measuring section A achieves, on the one hand, a compact design of the fire gas detector 5, and on the other hand, good space utilization in the plane E.

[0047] Fig.Figure 7 shows a second advantageous embodiment of the absorption measuring section A in a side view. The absorption measuring section A has a helical and simultaneously spiral shape, resembling a conical screw. The conical screw is understood to mean, in particular, a spiral path along the lateral surface of a cone. Thus, the spiral of the absorption measuring section A is, in particular, a three-dimensional, helical spiral. Due to its three-dimensional design, the absorption measuring section A has an axis L. To achieve the helical shape, the deflection sections 9 are arranged, for example, at different heights along the axis L. For instance, the spiral path of the absorption measuring section A has a constant pitch.

Claims

[1] Fire alarm device (1) with at least one fire gas detector (5) for detecting fire gases, wherein the at least one fire gas detector (5) comprises a light emitter (5a) for emitting light radiation and a light receiver (5b) for receiving the light radiation, with an absorption measurement section (A) that runs from the light emitter (5a) to the light receiver (5b), wherein the combustion gases can be detected by the light receiver (5b) depending on the light intensity of the light radiation received by the light receiver (5b), with a plurality of deflection sections (9) for deflecting the light radiation along the absorption measurement section (A), wherein the absorption measurement section (A) runs in a spiral and / or helical shape, wherein the deflection sections (9) comprise a curved surface such that the deflection sections (9) are focusing or defocusing. [2] Fire alarm device (1) according to claim 1, characterized by , that the deflection sections (9) are arranged spirally relative to each other. [3] Fire alarm device (1) according to claim 1 or 2, characterized by , that the absorption measurement section (A) is arranged in a plane (E). [4] Fire alarm device (1) according to claim 1 or 2, characterized by , that the absorption measurement path (A) runs in a three-dimensional path. [5] Fire alarm device (1) according to any one of the preceding claims, characterized by , that the light emitter (5a) is arranged radially outside to a center point (M) and / or to an axis (L) of the spiral path of the absorption measurement section (A) and the light receiver (5b) is arranged radially inside. [6] Fire alarm device (1) according to any one of the preceding claims, characterized by that the absorption measurement section (A) has at least one 360° rotation. [7] Fire alarm device (1) according to any one of the preceding claims, characterized by , that the fire alarm device (1) comprises at least a first, a second and a third deflection section (9a, 9b, 9c), wherein a first measuring absorption section (A1) is formed between the first and the second deflection section (9a, 9b) and a second measuring absorption section (A2) is formed between the second and the third deflection section (9b, 9c), wherein the second measuring absorption section (A2) is at most ten percent shorter than the first measuring absorption section (A1) if the diameter of the spiral absorption measuring section (A) increases or at most ten percent longer if the diameter of the spiral absorption measuring section (A) decreases. [8] Fire alarm device (1) according to any one of the preceding claims, characterized by, that a deflection angle (Alpha) between two adjacent deflection sections (9a / 9b, 9b / 9c) is at least 30°, in particular at least 50°, specifically at least 100° and / or at most 175°. [9] Fire alarm device (1) according to any one of the preceding claims, characterized by , that the deflection sections (9) comprise a metal layer, a dielectric layer and / or a multilayer layer. [10] Fire alarm device (1) according to any one of the preceding claims, characterized by a housing with an interface section for attachment to a support structure and with a sensor section, wherein the deflection sections (9), the light emitter (5a) and / or light receiver (5b) are arranged in the sensor section. [11] Fire alarm device (1) according to any one of the preceding claims, characterized by , that the fire alarm device (1) is designed as a wall detector or as a ceiling detector.

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