Stray light detector and suction fire detection system with a stray light detector

Description

[0001] The invention relates to a scattered light detector with the features of claim 1 for detecting particles, in particular smoke particles, in a test fluid, in particular for use in an intake fire detection system, with a test area which has a flow inlet and a flow outlet to form a flow path through which the test fluid can flow, a light transmitter which emits a light beam in an emission direction, wherein the emitted light beam forms an overlap region with the flow path, a light receiver for receiving a scattered light component scattered by particles in the overlap region, and a printed circuit board, wherein the light transmitter and the light receiver are connected as surface-mountable components to a front side of the printed circuit board facing the test area.The invention also relates to an intake fire detection system with the features of claim 11 having such a scattered light detector, wherein the intake fire detection system has one or more intake openings arranged in one or more monitoring spaces for sucking in a test fluid, a pipe and / or hose system for fluidically connecting the one or more intake openings to the scattered light detector, and an intake device for generating a flow and / or a negative pressure within the pipe and / or hose system. Finally, the invention relates to a corresponding method with the features of claim 13 for detecting particles contained in a test fluid, in particular smoke particles, in particular for detecting a fire.

[0002] In addition to fire detection and monitoring in a room using simple ceiling smoke detectors, scattered light detectors are suitable for use in so-called aspirating fire detection systems, also known as aspirating smoke detectors, which continuously suck in a sufficiently representative amount of test fluid, in particular air, from a monitored room, a room or area to be monitored, or an environment to be monitored, and feed it to the scattered light detector arranged in the intake path. The sucked in test fluid is guided along a flow path through a test area of ​​the scattered light detector, with a light beam emitted by the light transmitter being directed onto the test area. Diodes, so-called light-emitting diodes (LEDs), also simply referred to as light-emitting diodes, have proven suitable for use as light transmitters. A first sectional volume, in which the emitted orThe area where the transmitted light beam and the flow path of the test fluid overlap forms an overlap region within which any particles, in particular smoke particles, that may be sucked in cause the incident light to be scattered. In order to detect the scattered scattered light, the field of view of a light receiver, usually a photodiode (PD), is directed in a receiving direction towards the area of ​​intersection. A second intersection volume in which the light beam from the light transmitter and the field of view of the light receiver coincide is referred to as the scattered light center. A third intersection volume in which the overlap region and the scattered light center, i.e. the light beam from the light transmitter, the field of view of the light receiver and the flow path of the test fluid overlap, forms a detection volume. A scattered light component of any particles, in particular smoke particles, that may be present there cause a scattering of the incident light.The scattered light scattered by smoke particles is captured by the light receiver and used for fire detection via a downstream evaluation. Due to the high sensitivity of aspirating fire detection systems, fire detection is often possible even during the initial phase of a fire, which is why aspirating smoke detectors are classified as early fire detection or even early fire detection.

[0003] A generic photoelectric particle sensor for detecting scattered light scattered by particles for an intake fire detection system is known from EP 0 729 024 A2. The particle sensor comprises an optical chamber surrounded by a housing and having an air inlet and an air outlet. The optical chamber forms an air passage by directing the sucked-in air into the chamber via an air inlet and out of the chamber via an air outlet. The light transmitter and the light receiver are arranged within the optical chamber or protrude into it and are therefore in direct contact with the air passage. This leads to a complex structure of the optical chamber and the associated contamination, particle deposits and, as a result, to reduced responsiveness and an increased error rate of the particle sensor. To power the light transmitter and the light receiver, respectively.In order to transmit the received signals, structurally separate circuit carriers and / or printed circuit boards are also required, which results in increased manufacturing costs due to more complex production.

[0004] EP 3 029 647 B1 describes a scattered light smoke detector having a circuit board housed in a housing shell. Both a light-emitting diode (LED) as a light transmitter and a photodiode (LED) as a light receiver are connected to this circuit board. The smallest possible overall height for the scattered light smoke detector is achieved by connecting the diodes directly to the circuit board, i.e., immediately and without additional substructures, for example, as surface-mounted components (SMD). The emission direction or reception direction of conventional diodes is therefore necessarily orthogonal to the circuit board. In order to form a scattered light center, i.e., an intersection volume in which the emitted light beam of the LED and the field of view of the photodiode intersect, at least one of the diodes is designed as a so-called "side-looker" LED.By using such a "side-looker" LED, a "lateral" emission direction, parallel to the circuit carrier, can be achieved. The disadvantage of this design is, firstly, that the entire circuit carrier, including all active optical components, is located within the test fluid, in this case directly within the monitored space or the environment to be monitored. Secondly, the emission and reception directions of the diodes are limited to a parallel ("side-looker" diode) or orthogonal arrangement (conventional diode) with respect to the circuit carrier.

[0005] Various possible arrangements for the light receiver in relation to the light transmitter are known from the prior art. The angle spanned between the emission direction of the transmitted light beam and the line of sight of the light receiver is referred to as the scattering angle. A scattering angle between 0° and 90° is referred to as forward scattering, while a scattering angle greater than 90° is referred to as backward scattering. Various options for deflecting and / or reflecting the light beam emitted by an LED or the scattered light path of a scattered portion of the scattered light are also known from the prior art.

[0006] In the following and according to the common understanding, the term "reflection" describes the one-time change in direction of a light beam by means of a reflector, e.g., a mirror. A light beam striking the surface of the reflector is returned (reflected) by the reflector, with the angle of incidence of the light beam equal to the angle of reflection. The term "deflection" of a light beam, on the other hand, describes the change in the direction of the light beam by means of an optical fiber, e.g., an optical fiber. Unlike single reflection, the light beam enters the medium of the optical fiber and is transmitted within it, allowing any change in direction. The angle of incidence of the light beam into the optical fiber therefore does not have to correspond to the angle of emergence. In contrast, the term "focusing" of a light beam does not refer to a change in direction. Refraction, e.g., occurs when the light beam is reflected back to the surface.by means of a converging lens, the light intensity is increased and / or the width of the field of view of a photodiode or the light beam of a light-emitting diode is changed.

[0007] The use of a lens in the field of photoelectric detection is known, for example, from EP 2 881 719 A1 in connection with spark detection. Unlike with particle, particularly smoke particle, detection, the use of a light transmitter is not necessary in spark detection, as the sparks to be detected already serve as the light source themselves. The actual light receiver is arranged outside a channel through which a combined material and gas flow to be monitored flows. An optical rod transmits the radiation emitted by the sparks to the light receiver and projects into the channel, where it is shielded from the material and gas flow by a lens. At the same time, the width of the field of view is changed, in particular enlarged, depending on the design of the lens.

[0008] US Pat. No. 9,267,885 B2 discloses an optical scattered light detector in which it is proposed to change the emission direction of the light beam from a light-emitting diode and the scattered light path of a scattered portion of the scattered light by means of two light reflectors, in particular prisms, projecting into a measuring chamber. A first prism is directed toward the light-emitting diode to reflect its light beam at an angle into a detection zone within the measuring chamber, and a second prism is directed toward a photodiode to reflect the scattered light originating from the detection zone at the same angle toward the photodiode. The light reflectors are arranged on a common support member, which indirectly connects them to a circuit board.A similar design of a scattered light detector is also known from WO 2016 / 102891 A1. It differs from the previously described design essentially in that two optical fibers extending into the measuring chamber are used instead of the two prisms. The proposed arrangement of the diodes and the respective reflectors or optical fibers relative to each other allows only the detection of forward scattering within a limited scattering angle range.

[0009] An object of the present invention is therefore to provide a scattered light detector which is improved compared to the prior art and which, in particular, has a more cost-effective, more compact and more durable design while at the same time providing high response sensitivity that remains constant over the operating time, a lower false alarm rate and detection accuracy, in particular in order to meet the special requirements of an aspiration fire detection system, such as the comparatively small available installation space.

[0010] According to the invention, the object is achieved by a scattered light detector according to claim 1, an intake fire detection system with a scattered light detector according to claim 11 and a method for detecting particles contained in a test fluid, in particular smoke particles according to claim 13.

[0011] A scattered light detector according to the invention of the type described in more detail at the outset is characterized in that the light beam emitted by the light transmitter is guided into the test area by means of an optical fiber that deflects the light beam, and the light receiver is arranged such that a direct or indirect scattered light path runs between the light receiver and the intersection area.

[0012] According to the invention, the test area is delimited by a test area wall, wherein the test area wall has one or more recesses for receiving optical components and / or for generating a plurality of light passages, wherein the light transmitter and the light receiver as well as the circuit board having the light transmitter and the light receiver are arranged outside the test area wall delimiting the test area, wherein the light beam emitted by the light transmitter is guided into the test area by means of an optical fiber deflecting the light beam, wherein the light beam enters the medium of the optical fiber and is forwarded inside it.

[0013] According to the invention, the optical waveguide opens within one of the recesses of the test area wall, is received by one of the recesses or passes through one of the recesses, wherein a light passage or a non-reflective optical component is arranged within the direct scattered light path running between the light receiver and the intersection area and / or the indirect scattered light path running between the light receiver and the intersection area is formed by means of an optical waveguide arranged within one of the recesses of the test area wall and in the field of view of the light receiver.

[0014] In an advantageous embodiment, the light transmitter, in particular a light-emitting diode (LED) and / or the light receiver, in particular a photodiode (PD), are connected directly or immediately, i.e. without additional or intermediate substructures or as surface-mountable components (also referred to as SMD = Surface Mounted Device), to one side of the circuit board, to its front side, and point orthogonally away from the circuit board or the radiation direction of the light transmitter and the field of view of the light receiver are aligned orthogonally to the front side of the circuit board. The front side of the circuit board is the side of the circuit board that faces or is closest to the test area. In principle, all components mounted on the circuit board can be attached to the front of the circuit board.However, it is also conceivable to have components on both sides of the circuit board: the front side and the back side opposite the front side, away from the test area. For example, circuits for controlling the light transmitter or for amplifying and evaluating the light receiver signal can also be arranged on the circuit board.

[0015] Energy-converting optical components that consume or generate electrical energy, such as light transmitters or light receivers, are also referred to as active optical components. Optical components without significant energy conversion, such as lenses, optical fibers, or filters, are also referred to as passive optical components.

[0016] Advantageously, a light trap can also be arranged within the test area to absorb a non-scattered light portion of the light beam emitted by the light transmitter.

[0017] According to the invention, the light beam transmitted by the light transmitter, in particular extending orthogonally to the front side of the circuit board, is deflected by an optical waveguide and directed into the test area in order to form an intersection area with the test fluid flowing along the flow path within the test area. The light receiver is arranged on the circuit board in such a way that a direct scattered light path is formed between the intersection area and the light receiver, i.e. a straight, non-reflected and non-deflected path of a scattered light component scattered by a particle in the intersection area. Alternatively, the light receiver is arranged in such a way that an indirect scattered light path is formed between the intersection area and the light receiver, i.e.a "bent" and / or "curved", reflected and / or deflected path of a scattered light component scattered by a particle in the overlap area.

[0018] In other words, to form a direct scattered light path, the field of view of the light receiver is directed directly or immediately toward the intersection area in one receiving direction. In this way, the scattered light center, where the light beam of the light transmitter and the field of view of the light receiver intersect, can be positioned within the intersection area, where the emitted or transmitted light beam of the light transmitter and the flow path of the test fluid intersect, with a small number of optical components and thus with minimal effort, to form the detection volume.Accordingly, an indirect scattered light path is formed if the field of view of the light receiver is not directed directly or immediately onto the overlap area, but rather, in particular passive, optical components for reflecting or deflecting the scattered light component are arranged within the field of view of the light receiver and are thus used to place the scattered light center within the overlap area.

[0019] The invention therefore provides a modifiable structure of a scattered light detector with a multitude of arrangement options for optical components, in which all active optical components are arranged on a single circuit board, in particular on the front of this circuit board, the light beam of the light transmitter is deflected as required by an optical fiber to form the overlap region with the test fluid, and the light receiver is arranged as required and / or optionally to form a direct or an indirect scattered light path between the overlap region and the light receiver. In particular, a flexible structure enables adapted use of the scattered light detector for an intake fire detection system in that the light beam of the light transmitter can be directed onto the flow path of the test fluid and the light receiver is used to form the scattered light center orof the detection volume within the overlap region and for detecting the scattered light component scattered in the detection volume, the scattered light component is either directed directly at the overlap region or the overlap region lies within the field of view of the light receiver, or is directed indirectly at the overlap region or the overlap region lies outside the field of view of the light receiver, and the scattered light component is deflected or reflected by means of an optical component, in particular a passive one, preferably an optical waveguide. In this way, a minimal number of components, in particular active and passive optical components, can be realized, thereby reducing in particular the manufacturing effort and the resulting manufacturing costs.By arranging all active optical components on a single circuit board, additional manufacturing costs are saved and the design of the scattered light detector is significantly simplified. In a particularly advantageous embodiment, both all active optical components and passive optical components are arranged outside the flow path of the test fluid, in particular outside the test area, or only the passive optical component that deflects the light beam from the light transmitter, the optical fiber, extends into the test area. In this way, contamination of the test area due to particle deposits on optical components, which is particularly common in aspiration fire detection systems, can be significantly reduced or even completely avoided.

[0020] In an advantageous embodiment of the invention, the light beam emitted by the light transmitter runs in a radiation direction directed along the flow path.

[0021] As an alternative to this embodiment, the light beam emitted by the light transmitter preferably runs in a radiation direction directed towards the flow path.

[0022] Because the light beam emitted by the light transmitter is directed along the flow path, in particular parallel to the flow path, a larger overlap area between the light beam and the flow path can be created. To utilize the enlarged overlap area for multi-detection, i.e., the detection of scattered light using multiple light receivers, several respective scattered light centers can be placed within the flow path, for example, to create associated detection volumes in different areas of the test area.Alternatively, by aligning the light beam in a direction directed toward the flow path, particularly in a direction orthogonal to the flow path, a more precise delimitation of the detection volume is possible by creating a smaller overlap area between the light beam and the flow path. In addition to the borderline cases of a light beam directed parallel to the flow path, in which the intersection angle between the flow path of the test fluid and the emission direction of the light transmitter is 0°, or a light beam directed orthogonally to the flow path, in which the intersection angle is 90°, intermediate emission directions that span an intersection angle in a range between 0° and 90° are also adjustable.

[0023] An advantageous embodiment of the scattered light detector is characterized by the fact that a non-reflective, non-deflecting optical component or medium is arranged within the direct scattered light path extending between the light receiver and the intersection region. Such a non-reflective, non-deflecting optical component or medium is, for example, a lens or simple window glass.

[0024] In an alternative embodiment of the scattered light detector, the indirect scattered light path running between the light receiver and the overlap region is formed by an optical fiber that redirects the scattered light component. This allows the light receiver to be positioned at almost any position on the circuit board, thus allowing for better utilization of the available space.

[0025] According to this, a direct scattered light path contains either no optical components at all and only the medium present in the test area or the test fluid drawn into the test area, usually air, or only non-reflective or non-deflecting, particularly passive, optical components such as a lens or simple window glass. In contrast, an indirect scattered light path is preferably formed by an optical fiber that deflects the scattered light component.

[0026] According to a further preferred embodiment, a first planar optic for focusing the light beam is arranged between the light transmitter and the intersection region and / or a second planar optic for focusing a scattered light component scattered along the scattered light path is arranged between the light receiver and the intersection region.

[0027] By using planar, i.e. flat or planar optics, in particular lenses, for example converging or diverging lenses, but also so-called Fresnel lenses, the light beam of the light transmitter and / or the scattered light component scattered in the scattered light path can be focused and the width and / or light intensity of the light beam and / or the scattered light component or the field of view of a light receiver can be varied. Preferably, the first and / or second planar optics are aligned parallel or at an angle, in particular in a range between 0° and 45°, to the front of the circuit board and / or are arranged opposite an associated light transmitter or light receiver.

[0028] The placement of a converging lens in front of the light emitter, particularly the light-emitting diode, enables, for example, the formation of a point-like intersection area where the flow path of the test fluid and the light beam of the light emitter intersect. The placement of a converging lens in front of the light receiver, particularly the photodiode, on the other hand, results in an enlarged detection area. The scattered light incident on the converging lens is bundled, with the focal point aligned with the light receiver. This makes it possible to "intercept" and detect scattered light that would otherwise bypass the light receiver.

[0029] According to the invention, the test area is delimited by a test area wall, wherein the test area wall has one or more recesses for receiving optical components and / or for generating one or more light passages, wherein the light transmitter and the light receiver as well as the circuit board having the light transmitter and the light receiver are arranged outside the test area wall delimiting the test area.

[0030] Likewise, in a further development of this embodiment, the optical waveguide and / or the first planar optics and / or the second planar optics and / or further optical components can be arranged outside the test area, in particular outside the test area wall delimiting the test area.

[0031] According to the invention, a light passage or a non-reflective optical component is then arranged within the direct scattered light path running between the light receiver and the overlapping region and / or the indirect scattered light path running between the light receiver and the overlapping region is formed by means of an optical waveguide arranged within one of the recesses of the test area wall and in the field of view of the light receiver.

[0032] According to the invention, the optical fiber that deflects the light beam from the light transmitter opens within one of the recesses in the test area enclosure, or the optical fiber is accommodated within a recess. Alternatively, the optical fiber passes through the recess and opens into the test area. Optionally, the light receiver can be assigned to a lens located within a recess or a light passage, e.g., a gap formed within the test area enclosure, to form a direct scattered light path, so that only the medium and / or test fluid present in the monitored space or in the environment to be monitored, usually air, is located within the scattered light path.Preferably, the circuit board, the active optical components connected to it, and in particular all passive optical components are arranged outside the test area and accommodated within corresponding recesses so that the optical components are flush with the test area wall. This ensures particularly low contamination of the test area by particle deposits on the optical components and / or the test area wall, thus ensuring a particularly long service life of the scattered light detector.

[0033] If the test area enclosure has a circular-cylindrical cross-section, a flow with as little turbulence as possible, ideally even laminar, can be achieved within the test area. Furthermore, use in an aspiration fire detection system is considerably simplified. In a particularly preferred embodiment, it is therefore conceivable to use a section of the pipe and / or hose system of the aspiration fire detection system itself as the test area enclosure. Due to the variable arrangement and alignment options of the light receiver, the scattered light detector can be adapted to the geometric specifications of the aspiration fire detection system. By using a single circuit board to accommodate all active optical components and, if necessary,all other components for control and evaluation, a housing surrounding the test area wall and the circuit board arranged outside the test area wall can also be designed in a particularly space-saving manner and adapted to the limited installation space available.

[0034] According to an advantageous embodiment, the scattered light detector is characterized by one or more additional light receivers which are connected as secondary light receivers to the circuit board, in particular to the front side of the circuit board.

[0035] In a further development of this embodiment, the one or more secondary light receivers are arranged in such a way that a direct or indirect scattered light path runs between the respective secondary light receiver and the overlap area.

[0036] In addition to the light receiver, further auxiliary light receivers can thus be connected to the front of the circuit board, preferably adjacent to it. The one or more auxiliary light receivers are essentially identical to the light receiver, for example designed as a photodiode, and can each be designed optionally and / or as required in corresponding possible configurations and / or orientations and / or arrangements of the light receiver. In particular, the one or more auxiliary light receivers can be connected directly or indirectly to the circuit board and a direct or indirect scattered light path can run between the overlap region and the respective auxiliary light receiver. The one or more auxiliary light receivers can be used, for example, for multi-detection, i.e. for detecting scattered light components scattered at different scattering angles in the overlap region by means of multiple light receivers.In addition to forming multiple scattered light centers within the overlap region, each associated with a respective secondary light receiver, it is particularly expedient to arrange the one or more secondary light receivers and / or align their respective fields of view such that they form a common scattered light center within the overlap region or a common detection volume with the light transmitter. Optionally or alternatively, it is therefore conceivable to connect the one or more secondary light receivers to the circuit board at a respective detection angle in order to align their respective fields of view toward the overlap region in the required reception direction, in particular to form a common scattered light center within the overlap region and thus a common detection volume.By means of the light receiver and the one or more secondary light receivers, different scattered light components scattered in the common detection volume at different, characteristic or particle-specific scattering angles can be detected.

[0037] Due to the flexible arrangement options of the light receiver and one or more auxiliary light receivers, they can even be arranged on a common circuit board to save space, while simultaneously increasing the evaluation capabilities of the scattered light detector. In particular, the scattering angle-dependent scattered light distribution can be included in the evaluation, which, for example, distinguishes between fire and deceptive phenomena (e.g., dust or vapor particles).

[0038] In addition, one or more second planar optics for focusing a scattered light component in a respective scattered light path can be arranged between the one or more secondary light receivers and the overlap region.

[0039] Preferably, the one or more second planar optics are each aligned parallel or at an angle to the front side of the circuit board and / or arranged opposite the associated light secondary receiver and in particular accommodated within recesses of a test area wall surrounding the test area.

[0040] In a further development of the embodiment variant, it is then particularly advantageous that the one or more second planar optics are each arranged tangentially to a common circumference surrounding the flow path and / or each have the same distance from the overlap region.

[0041] For example, when using a test area enclosure with a circular-cylindrical cross-section, several second planar optics, in particular converging lenses, can be accommodated in recesses in the test area enclosure, which extend along a common circumference. In this arrangement, the planar optics, preferably designed as converging or Fresnel lenses, are each at the same distance from the flow path of the test fluid, which expediently runs along a central axis of the test area enclosure, or from the area where the light beam of the light transmitter overlaps the flow path. This simplifies focusing the respective reception direction of the secondary light receivers within a common detection volume and simultaneously increases the width of the respective field of view.

[0042] Finally, according to an advantageous embodiment, at least one polarization filter can be arranged within the respective direct or indirect scattered light path of two or more of the light sub-receivers or of the light receiver and at least one of the light sub-receivers.

[0043] Preferably, the polarization planes of the polarization filters are orthogonal to each other, whereby additional analysis information can be obtained based on the filtered scattered light component.

[0044] An inventive intake fire detection system of the type described in more detail at the outset with a scattered light detector according to one of the previously described embodiments is characterized in that a test area of ​​the scattered light detector is designed as an integrated component of the pipe and / or hose system, in that the test area is designed as a flow section, in particular a supply pipe, of the pipe and / or hose system.

[0045] According to the invention, it is therefore also provided to provide an air intake fire detection system with an integrated scattered light detector. The scattered light detector is designed as an integrated, preferably even integral, component of the pipe and / or hose system. In the integrated design, the scattered light detector is installed in the pipe and / or hose system in such a way that the flow enters the test area through an inlet of the detector and leaves it again through a detector outlet. In the integral design, the pipe and / or hose wall even simultaneously forms the test area wall, so that the test area can be inserted into the pipe and / or hose system, for example as a so-called pipe fitting. In this way, even existing air intake fire detection systems can be easily and simply retrofitted with the scattered light detector according to the invention.

[0046] An advantageous embodiment of the suction fire detection system is characterized in that a test area wall delimiting the test area is arranged in the flow direction of the test fluid in front of, in particular immediately in front of, the suction device.

[0047] The scattered light detector is expediently arranged within the pipe and / or hose system of the air intake fire detection system, in particular directly in front of its suction device. On the one hand, this allows the longest possible, straightest flow path of the test fluid within the pipe and / or hose system to be used, thereby achieving a more even distribution of the particles within the test fluid and a flow of the test fluid with less turbulence. On the other hand, test fluid quantities originating from different branches of the pipe and / or hose system and taken from a respective interstitial space can be checked and evaluated using the same scattered light detector. To determine the origin or localize the different test fluid quantities, the use of additional, decentralized scattered light detectors within, particularly in different branches of the pipe and / or hose system is advisable.Preferably, these decentralized scattered light detectors are also designed according to at least one embodiment of the present invention.

[0048] In a method according to the invention for detecting particles contained in a test fluid, in particular smoke particles, using a scattered light detector, in particular according to one of the previously described embodiments, which scattered light detector has a light transmitter for forming an overlapping region and a light receiver for detecting scattered light scattered within the overlapping region, a test fluid is continuously withdrawn from one or more monitoring spaces by means of one or more suction openings and fed to the scattered light detector by means of a fluid-conducting pipe and / or hose system.

[0049] The method according to the invention is characterized in that the overlap region is formed within the pipe and / or hose system, and the light receiver is directed toward the overlap region to form a detection volume. A flow path carrying the test fluid is generated along a flow section of the pipe and / or hose system, and the light transmitter emits a light beam in a direction directed toward the flow path or along the flow path, the emitted light beam forming the overlap region with the flow path. Optionally, the light receiver receives at least a portion of the scattered light scattered within the overlap region, provided particles are present within the test fluid.

[0050] Within the scope of the invention, it is therefore provided to form the overlap region within the pipe and / or hose system in that both the light beam emitted by the light transmitter and the flow path carrying the test fluid meet within a flow section of the pipe and / or hose system. For this purpose, the flow section can be integrated into the pipe and / or hose system, i.e., a test region surrounded by a preferably circular-cylindrical test region wall replaces a flow section of the pipe and / or hose system or is additionally interposed, or can be formed integrally with the pipe and / or hose system, i.e., a flow section of the pipe and / or hose system itself is used as the test region within which the flow path is formed.To detect at least a portion of the scattered light scattered within the overlapping area, the light receiver, in particular its field of view, is also directed toward the overlapping area, forming a scattered light center, in particular a detection volume, within the pipe and / or hose system. A scattered light path extending between the overlapping area and the light receiver can be formed either directly or indirectly, as required and / or as required.

[0051] Further steps for evaluating the detected scattered light component for the presence of a fire or a fire hazard or the risk of a fire occurring are sufficiently known from the state of the art.

[0052] It should be noted that the features and measures listed individually in the preceding and following descriptions can be combined in any technically reasonable manner and demonstrate further embodiments of the invention. The description further characterizes and specifies the invention, particularly in conjunction with the figures.

[0053] Further advantageous embodiments of the invention are disclosed in the following description of the figures. Figure 1 shows an exemplary, schematic representation of an inventive suction fire detection system with an integrated scattered light detector, Figure 2 shows a schematic representation of a first exemplary embodiment of an inventive scattered light detector with a light beam transmitted along a flow path and a direct scattered light path, Figure 3 shows a schematic representation of a second exemplary embodiment of an inventive scattered light detector with a light beam transmitted along a flow path and a circular-cylindrical test area enclosure, Figure 4 shows a schematic representation of a third exemplary embodiment of an inventive scattered light detector with a light beam directed onto the flow path and a direct scattered light path,Figure 5 shows a schematic representation of a fourth exemplary embodiment of a scattered light detector according to the invention with a light beam directed and focused onto the flow path and a direct and focused scattered light path. Figure 6 shows a schematic representation of a fifth exemplary embodiment of a scattered light detector according to the invention with a light beam directed and focused onto the flow path and an indirect and focused scattered light path. Figure 7 shows a schematic representation of a sixth exemplary embodiment of a scattered light detector according to the invention with a light beam directed and focused onto the flow path and a plurality of secondary light receivers which are aligned for multi-detection at a respective detection angle. Figure 8 shows a schematic representation of a seventh exemplary embodiment of a scattered light detector according to the invention with a plurality of secondary light receivers.which are aligned for multi-detection at a respective detection angle, wherein a polarization filter is arranged in a respective direct scattered light path, Figure 9 shows a schematic representation of an eighth exemplary embodiment of a scattered light detector according to the invention with several light sub-receivers, which are aligned for multi-detection at a respective detection angle and a respective indirect scattered light path is formed by means of an optical fiber, and Figure 10 shows an exemplary flow diagram of a method according to the invention.

[0054] In the different figures, identical parts are always provided with the same reference symbols, which is why they are usually only described once.

[0055] While the viewer’s line of sight in the Figures 2 and 3 orthogonal to the flow of the test fluid, the Figures 4 to 9 as views inFlow direction of the test fluid.

[0056] In the Figure 1An exemplary, schematic representation of an inventive suction fire detection system 100 with an integrated scattered light detector 200 is shown. The suction fire detection system 100 has a pipe and / or hose system 110 with a first pipe branch 111 and a second pipe branch 112. The pipe branches 111, 112 each comprise a plurality of suction openings 120, which are arranged in one or more monitoring spaces 300 for sucking in a test fluid. For example, it is conceivable that the first pipe branch 111 and the second pipe branch 112 are arranged in different, structurally separate monitoring spaces 300, with each monitoring space 300 being assigned a plurality of suction openings 120. The pipe and / or hose system 110 also has a supply pipe 113 for the fluid-conducting connection of the intake openings 120 and the pipe branches 111, 112 to the scattered light detector 200.To generate a negative pressure and / or a flow within the pipe and / or hose system 110, a suction device 130 is provided. By means of the suction device 130, a respective quantity of test fluid can be withdrawn from the one or more monitoring spaces 300 via the suction openings 120 and fed to the scattered light detector 200 via the pipe and / or hose system 110 in a flow direction P of the test fluid, which is indicated by the arrows. The scattered light detector 200 is designed here as an integrated component of the pipe and / or hose system 110 in that its test area 210, which is delimited by a test area wall 211, replaces a flow section and / or line section, in particular of the supply pipe 113 of the pipe and / or hose system 110, and is arranged directly upstream of the suction device 130 in the flow direction P of the test fluid.The scattered light detector 200 and the suction device 130 are enclosed by a common housing 140.

[0057] A schematic representation of a first exemplary embodiment of a scattered light detector 200 according to the invention can be Figure 2The scattered light detector 200 has a test area 210, which is delimited by a tubular or cylindrical test area wall 211. To form a flow path 310 through which a test fluid can flow, indicated by arrows, the test area 210 further has a flow inlet 212 and a flow outlet 213. The cross section of the flow path 310 formed within the test area 210, shown by dashed lines, approximately corresponds to the cross section of the flow inlet 212 and the flow outlet 213 or is formed by them. The flow inlet 212 can be connected to a pipe and / or hose system 110 of an aspiration fire detection system 100, and the flow outlet 213 can be arranged directly upstream of an aspiration device 130 of the aspiration fire detection system 100 (see Figure 1) or connected to the pipe and / or hose system 110. A light transmitter 230, in particular a light-emitting diode, and a light receiver 240, in particular a photodiode, are each directly connected to the front of a circuit board 220 and optically separated from each other by an opaque separating device 221. The circuit board 220 and the active optical components connected to it, the light transmitter 230 and the light receiver 240, are arranged both outside the test area 210 and outside the test area wall 211. This prevents unforeseeable flow turbulence and particle deposits, which lead to contamination of the test area 210 and thus to a shorter service life of the scattered light detector 200. In order to establish an optical connection between the light transmitter 230 and the light receiver 240 with the test area 210, the test area wall 211 comprises two recesses 214.The light transmitter 230 and the light receiver 240 point orthogonally away from the circuit board 220 and are directed toward the test area 210. A light beam 231, initially emitted by the light transmitter 230 orthogonally to the front side of the circuit board 220, is deflected by an optical fiber 232 to extend in an emission direction A directed along the flow path 310. For this purpose, the optical fiber 232 assigned to the light transmitter 230 is arranged penetrating a recess 214 in the test area wall 211 and deflects the light beam 231 in an emission direction A, here parallel to the front side of the circuit board 220. A first intersection volume, formed by the light beam 231 and the flow path 310, is designated as the intersection area X.

[0058] The light receiver 240 is also directed with its field of view toward the test area 210 in a receiving direction E extending orthogonally to the front side of the circuit board 220, whereby the light beam 231 of the light transmitter 230 and the field of view of the light receiver 240 form a second intersection volume, a so-called scattered light center. For scattered light detection, the scattered light center is placed within the flow path 310, thereby defining a third intersection volume, a detection volume D, in which the light beam 231 of the light transmitter 230, the field of view of the light receiver 240, and the flow path 310 of the test fluid intersect. A scattered light component 233 scattered within the detection volume D can be detected by the light receiver 240.

[0059] When smoke is generated, smoke particles 320 are contained within the overlapping area X, which are sucked in from one or more monitored spaces 300. A portion of the light beam 231 striking a smoke particle 320 is scattered in several directions, including at a scattering angle α. The scattering angle α shown as an example is approximately 90° in the present case, whereby the scattering just falls within the range of what is known as forward scattering (α=0°-90)°. A direct scattered light path S is formed between the overlapping area X and the light receiver 240, i.e. a straight, non-reflected and non-deflected path of a scattered light component 233 scattered by a smoke particle 320 in the overlapping area X, which runs through a recess 214, designed as a light passage or gap, in the test area wall 211 and strikes the light receiver 240.For optimized detection of the scattered scattered light component 233, the receiving direction E of the light receiver 240 is directed opposite to the scattered light path S.

[0060] From the Figure 3 A schematic representation of a second exemplary embodiment of a scattered light detector 200 according to the invention can be seen. From the first embodiment (see Figure 2), the second embodiment of the scattered light detector 200 differs in that it has a test area wall 211 that delimits the test area 210 in a tubular or cylindrical manner and has a circular-cylindrical cross-sectional area whose diameter corresponds to the diameter of the pipe and / or hose system 110. In order to design the test area wall 211 as an integral component of an aspiration fire detection system 100, it is advantageous to adapt the diameter of the circular-cylindrical cross-sectional area to the diameter of the pipe and / or hose system 110, in particular to design it with an identical inner diameter. The test area wall 211 can then form an integral component of the pipe and / or hose system 100 as a so-called pipe fitting, or a line or flow section of the pipe and / or hose system 110, in particular of the supply pipe 113, can be used as the test area wall 211 for the scattered light detector 200.In this embodiment, the flow inlet 212 and the flow outlet 213 are directly flush with adjacent lines of the pipe and / or hose system 110 of the intake fire detection system 100. This results in the flow path 310 being configured to extend substantially within the entire test area 210. Due to the cylindrical geometry of the test area wall 211, corners and / or dead flow spaces, within which contamination from particle deposits can easily occur, can be avoided. Furthermore, the flow path 310 is preferably configured within the entire test area 210, whereby all particles 320 contained within the test fluid are captured by the flow and thus more easily transported out of the test area 210 via the flow outlet 213.

[0061] A third exemplary embodiment of a scattered light detector 200 according to the invention is shown in Figure 4shown schematically. The third embodiment of the scattered light detector 200 also has a test area wall 211 with a circular-cylindrical cross-sectional area, which can be integrated into either a pipe and / or hose system 110 of an aspiration fire detection system 100 (see Figure 1 ) or even as an integral part of the pipe and / or hose system 110 (see Figure 3 ) can be formed. A flow path 310 is formed within the test area 210 and runs along the central axis of the test area wall 211, which is cylindrical or has a circular-cylindrical cross-section. Unlike the second embodiment (see Figure 3), the light beam 231 emitted by the light transmitter 230 is directed onto the flow path 310 and extends in an emission direction A substantially radially or orthogonally to the flow path 310. In this configuration, it is possible to arrange not only the circuit board 220 comprising the light receiver 240 and the light transmitter 230, but also the optical waveguide 232, which deflects the light beam 231 emitted by the light transmitter 230, outside the test area 210 and outside the test area wall 211. As a result, all optical components, both active and passive, are located outside the test area 210, enabling a smooth, low-turbulence flow of test fluid along the flow path 310. This contributes to improved detection of the scattered scattered light and, due to less contamination, to a longer service life of the scattered light detector 200.Conveniently, a light trap 250 can additionally be arranged within the test area 210 for absorbing a non-scattered light portion of the light beam 231 emitted by the light transmitter 230. The light trap 250 is preferably designed as a complete or partial coating of the inner surface of the test area wall 211, but could alternatively also be arranged as an optical component within the test area 210.

[0062] In the Figure 5 A schematic representation of a fourth exemplary embodiment of a scattered light detector 200 according to the invention is shown. Compared to the third embodiment (see Figure 4), the scattered light detector 200 shown here differs in that the light beam 231 emitted by the light transmitter 230 and directed radially onto the flow path 310 is focused by means of a first planar optic 261, in particular a converging lens or Fresnel lens. For this purpose, the first planar optic 261 is arranged within a recess 214 of the test area wall 211 and is connected to the optical fiber 232, which deflects the light beam 231 emitted by the light transmitter 230. As shown, the width of the light beam 231 is reduced by the first planar optic 261 and the light beam 231 itself is parallelized. Accordingly, an overlap area X between the flow path 310 of the test fluid and the light beam 231 is smaller than with a non-focused light beam, which enables more precise detection of the scattered scattered light.Additionally, an optional light trap 250 can be configured with a correspondingly smaller size. The first planar optic 261 could also be designed as a simple window glass to simply close the opening 214, preventing the test fluid from escaping through the recess 214.

[0063] On the other hand, the direct scattered light path S, which runs between the overlap region X or the detection volume D and the light receiver 240, is also focused by means of a second planar optic 262, in particular a converging lens or Fresnel lens. The scattered light component 233 incident on the second planar optic 262 is bundled and focused on the light receiver 240. In this way, it is possible to "intercept" and detect scattered light components that would otherwise pass by the light receiver 240. Furthermore, the emission direction A of the light transmitter 230 in this embodiment does not run parallel to the front side of the circuit board 220, so that the scattering angle α, shown here as an example, at which the light beam 231 emitted by the light transmitter 230 is scattered by a particle 320, is greater than 90°, which is why this can be referred to as so-called backscattering (α>90°).Here too, it is fundamentally conceivable that the second planar optic 262 is alternatively designed as a simple window glass.

[0064] A schematic representation of a fifth exemplary embodiment of a scattered light detector 200 according to the invention with an indirect and focused scattered light path S can be Figure 6 From the fourth embodiment described above (see Figure 5), the present fifth embodiment again differs in terms of the scattering angle α. According to the illustration, the light beam 231 emitted by the light transmitter 230 is scattered by a particle 320 at a scattering angle α of less than 90°, so that the present scattering can be classified as forward scattering. The scattered light component 233 scattered at the scattering angle α runs along an indirect scattered light path S, i.e., the scattered light component 233 running along the scattered light path S is deflected by an optical fiber 241 assigned to the light receiver 240 and arranged in its field of view, so that it has a "curved" path. Advantageously, the area of ​​the circuit board 220 required to detect a scattered light component 233 scattered forward at an angle between 0° and 90° can be reduced in this way.By deflecting the scattered light component 233 by means of the optical waveguide 241 assigned to the light receiver 240, the distance required between the light transmitter 230 and the light receiver 240 on the circuit board 220 is reduced, making the circuit board smaller overall and thus requiring less space. In particular, the deflection by means of the optical waveguide 241 makes it possible to detect forward scattering via a scattered light detector 200 with a single circuit board 220, the front of which has both the light transmitter 230 and the light receiver 240. For focusing, a second planar optic 262 is provided within the scattered light path S. This second planar optic is arranged in a recess 214 in the test area enclosure 211 and in front of the optical waveguide 241 with respect to the direction of the scattered light path S.

[0065] In the Figure 7A schematic representation of a sixth exemplary embodiment of a scattered light detector 200 according to the invention, which is provided for multi-detection, is shown. Similar to the fifth embodiment (see Figure 6 ), a light beam 231 emitted by the light transmitter 230 is deflected by means of an optical fiber 232 and directed onto the flow path 310 running within the test area 210, wherein the light beam 231 is focused by means of a first planar optic 261. As shown in the figure, the light beam 231, unlike in the fifth embodiment (see Figure 6), is deflected by an angle of approximately 90°, so that the light beam 231 runs substantially parallel to the front side of the circuit board 220. Together with the flow path 310, the light beam 231 forms the overlap region X. In addition to the light transmitter 230 and the light receiver 240, which are each directly connected to the front side of the circuit board 220, further auxiliary light receivers 240a, 240b, 240c in this figure are each indirectly connected to the front side of the circuit board 220, i.e. via additional substructures or surface-mounted components 242a, 242b, 242c.The surface-mounted components 242a, 242b, 242c are embodied here, for example, as a solid support base whose support surface is pivoted by a respective detection angle β relative to the front side of the circuit board 220 and is connected to the respective associated auxiliary light receiver 240a, 240b, 240c, so that the auxiliary light receivers 240a, 240b, 240c themselves are aligned at a respective detection angle β for multi-detection. The detection angle β spans between the front side of the circuit board 220 and the respective reception direction E. Alternatively, it is conceivable that the secondary light receivers 240a, 240b, 240c are each connected directly, i.e., without additional substructures or surface-mounted components 242a, 242b, 242c, to the front of the circuit board 220. Suitable planar optics 262 can ensure sufficient light incidence on the secondary light receivers 240a, 240b, 240c even if the secondary receivers are not adjusted.While the indirect connection and alignment of the secondary light receivers 240a, 240b, 240c using substructures can achieve a somewhat higher efficiency in light reception, the direct connection represents a more cost-effective variant.

[0066] The respective detection angles β of the light receiver 240 and the secondary light receivers 240a, 240b, 240c are selected accordingly to form a common scattered light center with the light beam 231 within the overlap area X and thus to form a common detection volume D. Starting from a particle 320 located within the detection volume D, a direct scattered light path S of a scattered light component 233 scattered at a corresponding scattering angle α strikes the light receiver 240 or the secondary light receivers 240a, 240b, 240c (shown schematically here as an example using the secondary light receiver 240c). Several second planar optics 262, which are arranged within corresponding recesses 214, each serve to focus the scattered light path S.Due to the flexible arrangement options of the light receiver 240 and the one or more secondary light receivers 240a, 240b, 240c, these can be arranged on a common circuit board 220 in a space-saving manner, while simultaneously increasing the evaluation options of the scattered light detector 200. In particular, the scattering angle α-dependent scattered light distribution can be included in the evaluation, which, for example, distinguishes between fire and deceptive quantities (dust or vapor particles).

[0067] A schematic representation of a seventh exemplary embodiment of a scattered light detector 200 according to the invention, which is provided for multi-detection, can be found in the Figure 8 As in the sixth embodiment (see Figure 7), the light receiver 240 and the auxiliary light receivers 240a, 240b, 240c are aligned at a respective detection angle β to form a common detection volume D. The auxiliary light receivers 240a, 240b, 240c are each indirectly connected to the circuit board 220 via an associated surface-mounted component 242a, 242b, 242c, but here formed as an inclined sheet metal. In addition, according to the present embodiment, polarization filters 243, 243a, 243b, 243c are also arranged within the respective direct and focused scattered light path S. Preferably, the polarization planes of two polarization filters 243, 243a, 243b, 243c are orthogonal to each other, whereby additional analysis information can be obtained based on the scattered light component 233 detected in a filtered manner.

[0068] In the Figure 9A schematic representation of an eighth exemplary embodiment of a scattered light detector 200 according to the invention, which is provided for multi-detection, is shown. Unlike the previously described sixth and seventh embodiments (see Figure 7 , 8 ), the respective scattered light path S has a "curved" course or is formed indirectly. By using a respective optical waveguide 241, 241a, 241b, 241c, it is possible to determine the detection angle β by deflecting the respective scattered light component 233, without the use of additional surface-mounted components 242a, 242b, 242c (see Figures 7 and 8). The secondary light receivers 240a, 240b, 240c can thus also be connected directly, i.e. directly and without additional substructures, to the front of the circuit board 220. Furthermore, in this embodiment, the distance between the secondary light receivers 240a, 240b, 240c and the light transmitter 230 required to detect the scattered light component 233 scattered at the associated scattering angle α is smaller, so that the circuit board 220 can be designed with a smaller area in favor of an overall smaller scattered light detector 200.

[0069] The different embodiments described according to the Figures 2 - 9represent merely an exemplary excerpt of the many possible modifications of a scattered light detector 200 according to the invention. Further embodiments are conceivable in any combination of the proposed construction and / or arrangement and / or modification options. In particular, a flexible design enables an adapted use of the scattered light detector 200 for an aspiration fire detection system 100 in that the light beam 231 of the light transmitter 230 can be directed onto the flow path 310 of the test fluid or aligned along the flow path of the test fluid. By using optical fibers 232, 241, 241a, 241b, 241c, the size of the circuit board 220 and thus the size of the scattered light detector 200 can be reduced overall, so that multi-detection with several auxiliary light receivers 240a, 240b, 240c is simplified or even feasible.By arranging all active optical components (light transmitter 230, light receiver 240, light sub-receivers 240a, 240b, 240c) on a single circuit board 220, additional manufacturing costs are saved and the structure of the scattered light detector 200 is considerably simplified. The possibility of arranging all active optical components (light transmitter 230, light receiver 240, secondary light receivers 240a, 240b, 240c) as well as passive optical components (optical waveguides 232, 241, 241a, 241b, 241c, planar optics 261, 262, polarization filters 243, 243a, 243b, 243c) outside the test area 210 and outside or flush with the test area wall 211 leads to the prevention of contamination of the test area 210 by particle deposits, which occur particularly frequently in suction fire detection systems 100, and as a result the service life of the scattered light detector 200 is increased.Modifications such as the use of planar optics 261, 262 or polarization filters 243, 243a, 243b, 243c improve the detection accuracy and the evaluation options.

[0070] To illustrate a method according to the invention for detecting particles 320 contained in a test fluid using a scattered light detector 200, preferably according to one of the exemplary embodiments described above, the Figure 10 An exemplary, schematic flow diagram of such a method can be seen. The method according to the invention is preferably carried out continuously for the continuous monitoring of a monitoring space 300. For easier understanding, the process sequence is explained step by step below using a single sampled test fluid quantity.

[0071] A quantity of test fluid is first taken from one or more interstitial spaces 300 via one or more intake openings 120 of an intake fire detection system 100. The taken quantity of test fluid is then fed to the scattered light detector 200 through a fluid-conducting pipe and / or hose system 110 (see also Figure 1). The scattered light detector 200, more precisely its test area 210, is integrated into the pipe and / or hose system 110 or formed integrally therewith, so that a flow path 310 is created along a flow section of the pipe and / or hose system 110, which then functions as the test area 210. Subsequently, an overlap area X is formed within the test area 210 and consequently within the pipe and / or hose system 110 by a light transmitter 230 emitting a light beam 231 in an emission direction A directed toward the flow path 310 or along the flow path 310. The light receiver 240 is directed toward the overlap area (X) to form a detection volume (D). If particles 320 are present within the aspirated test fluid quantity, a scattered light component 233 scattered by a particle 320 within the detection volume D is received by the light receiver 240 (see, for example, also Figure 2).

[0072] Within the scope of the invention, it is therefore provided to form the overlap region X within the pipe and / or hose system 110 of an intake fire detection system 100 in which both the light beam 231 emitted by the light transmitter 230 and the flow path 310 carrying the test fluid meet within a flow section of the pipe and / or hose system 110 and, at the same time, the field of view of the light receiver 240 is directed towards them in a receiving direction E. According to the invention, the scattered light center, the intersection volume between the field of view of the light receiver 240 and the light beam 231 of the light transmitter 230, is therefore also formed within a flow section of the pipe and / or hose system 110. A scattered light path 310 running between the overlap region X and the light receiver 240 can be formed directly or indirectly, as required and / or as required.Further steps for evaluating the detected scattered light component for the presence of a fire or a fire hazard or the risk of a fire occurring are sufficiently known from the state of the art. Reference symbol

[0073] 100Intake fire detection system 110Pipe and / or hose system 111First pipe branch 112Second pipe branch 113Supply line 120Intake opening 130Intake device 140Housing 200 Scattered light detector 210 Test area 211 Test area enclosure 212 Flow inlet 213 Flow outlet 214 Recess 220 Circuit board 221 Separator 230 Light transmitter 231 Light beam 232 Optical fiber 233 Scattered light component 240 Light receiver 240a, 240b, 240c Light secondary receiver 241 Optical fiber 241a, 241b, 241c Optical fiber 242a, 242b, 242c Surface-mounted components 243 Polarization filter 243a, 243b, 243c Polarization filter 250 Light trap 261 First planar optic 262 Second planar optic 300Interstitial space 310Flow path 320Smoke particles AEmission direction DDetectification volume EEception direction PFlow direction SScattered light path XOverlap area αScattering angle βDetection angle

Claims

1. A scattered light detector (200) for detecting particles, especially smoke particles (320) in a test fluid, for use in an intake fire detection system (100), with - a test area (210) which has a flow inlet (212) and a flow outlet (213) to form a flow path (310) through which the test fluid can flow, - a light transmitter (230) which emits a light beam (231) in the direction of the emission (A), wherein the emitted light beam (231) forms an overlapping area (X) with the flow path (310), - a light receiver (240) for receiving a scattered light component (233) scattered at particles (320) in the overlapping area (X), - a printed circuit board (220), wherein the light transmitter (230) and the light receiver (240) are connected to a front side of the printed circuit board (220) facing the test area (210) as surface-mountable components, and - the light receiver (240) is arranged in such a way that a direct or indirect path of scattered light (S) runs between the light receiver (240) and the overlapping area (X), characterised in that - the test area (210) is bounded by a test area wall (211), the test area wall (211) having one or more recesses (214) for accommodating optical components and / or for generating a plurality of light apertures, wherein - the light transmitter (230) and the light receiver (240) as well as the printed circuit board (220) comprising the light transmitter (230) and the light receiver (240) are arranged outside the test area wall (211) delimiting the test area (210), - the light beam (231) transmitted by the light transmitter (230) is guided into the test area (210) by means of a fibre optic cable (232) which deflects the light beam (231), the light beam (231) entering the medium of the fibre optic cable (232) and being passed on inside the latter, - the fibre optic cable (232) opens out within one of the recesses (214) of the test area wall (211), is received by one of the recesses (214) or passes through one of the recesses (214), and - a light aperture or a non-reflective optical component is arranged within the direct scattered light path (S) extending between the light receiver (240) and the overlapping area (X) and / or - the indirect path of scattered light (S) extending between the light receiver (240) and the overlapping area (X) is formed by means of a fibre optic cable (232) arranged within one of the recesses (214) of the test area wall (211) and in the field of view of the light receiver (240).

2. The scattered light detector (200) in accordance with claim 1, characterised in that the light beam (231) emitted by the light transmitter (230) runs in an emission direction (A) that is directed along the flow path (310).

3. The scattered light detector (200) in accordance with claim 1, characterised in that the light beam (231) emitted by the light transmitter (230) extends in an emission direction (A) that is directed towards the flow path (310).

4. The scattered light detector (200) in accordance with any one of claims 1 - 3, characterised in that the indirect path of scattered light (S) extending between the light receiver (240) and the overlapping area (X) is formed by means of a fibre optic cable (241) deflecting the scattered light component (233).

5. The scattered light detector (200) in accordance with any one of the preceding claims, characterised in that a first planar optical system (261) for focussing the light beam (231) is arranged between the light transmitter (230) and the overlapping area (X) and / or a second planar optical system (262) for focussing a scattered light component (233) scattered along the scattered light path (S) and which is arranged between the light receiver (240) and the overlapping area (X).

6. The scattered light detector (200) in accordance with any one of the preceding claims, characterised in that the fibre optic cable (232, 241) and / or the first planar optic system (261) and / or the second planar optic system (262) and / or further optical components are arranged outside the test area (210), especially outside the test area wall (211) delimiting the test area (210).

7. The scattered light detector (200) in accordance with any one of the preceding claims, characterised in that a light aperture or a non-reflective optical component is arranged within the direct path of scattered light (S) extending between the light receiver (240) and the overlapping area (X), or the indirect path of scattered light (S) extending between the light receiver (240) and the overlapping area (X) is formed by means of an optical fibre (241) arranged within one of the recesses (214).

8. The scattered light detector (200) in accordance with any one of the preceding claims, characterised in that one or more additional light receivers are connected as secondary light receivers (240a, 240b, 240c) to the printed circuit board (220), especially to a front side of the printed circuit board (220).

9. The scattered light detector (200) in accordance with claim 8, characterised in that the one or more secondary light receivers (240a, 240b, 240c) are arranged in such a way that a direct or indirect path of scattered light (S) runs between the respective secondary light receiver (240a, 240b, 240c) and the overlapping area (X).

10. The scattered light detector (200) in accordance with either claim 8 or 9, characterised in that one or more second planar optics (262) for focussing a scattered light component (233) are arranged in a respective path of scattered light (S) between the one or more secondary light receiver (240a, 240b, 240c) and the overlapping area (X).

11. An intake fire detection system (100) comprising a scattered light detector (200) in accordance with any one of claims 1 -10, wherein the intake fire detection system (100) comprises one or more aspirating openings (120) arranged for aspirating a test fluid in one or more monitored spaces (300), a pipe and / or hose system (110) for a fluid-conducting connection of the one or more intake openings (120) to the scattered light detector (200) and a suction device (130) for generating a flow and / or a negative pressure within the pipe and / or hose system (110), characterised in that a test area (210) of the scattered light detector (230) is designed as an integral component of the pipe and / or hose system (110), in that the test area (210) is designed as a flow section of the pipe and / or hose system (110).

12. The intake fire detection system (100) in accordance with claim 11, characterised in that a test area wall (211) delimiting the test area (210) has a flow inlet (212) which is arranged upstream of the test area (210) to form and / or align a flow path (310) within the test area (210), in the direction of flow (P) of the test fluid, and has a flow outlet (213) which is arranged downstream of the test area (210) and upstream of the intake device (130) in the direction of flow (P) of the test fluid.

13. A method for detecting particles contained in a test fluid, especially smoke particles (320), and especially for recognising a fire and / or the development of a fire, using a scattered light detector (200) according to any one of claims 1 -10, wherein the scattered light detector (200) has a light transmitter (230) for forming an overlapping area (X) with the test fluid and a light receiver (240) for detecting scattered light that has been scattered within the overlapping area (X) and wherein a test fluid is continuously withdrawn from one or more monitored spaces (300) by means of one or more suction openings (120) and supplied to the scattered light detector (200) by means of a fluid-conducting pipe and / or hose system (110), characterised in that the overlapping area (X) is formed within the pipe and / or hose system (110) and the light receiver (240) is directed towards the overlapping area (X) to form a detection volume (D), wherein - a flow path (310) carrying the test fluid is generated along a flow section of the pipe and / or hose system (110), and - the light transmitter (230) emits a light beam (231) in an emission direction (A) directed towards the flow path (310) or along the flow path (310), wherein the emitted light beam (231) forms the overlapping area (X) with the flow path (310).