Particle detection unit with detection chamber and flow guide component

Abstract

The invention relates to a particle detection unit (100) for use with an aspirating particle detection system, said particle detection unit having: a housing (110) comprising a detection chamber (120) which is provided therein, is shielded from ambient light and comprises a flow inlet (121) for introducing a fluid flow (F) and a flow outlet (122) for discharging the fluid flow (F); and a light emitter (130) and a light receiver (140) which are aligned with each other such that a detection region (DB) for detecting particles contained in the fluid flow (F) is defined by the superimposition of the light emitted from the light emitter (130) and the area of incidence of the light receiver (140) within the detection chamber (120). The aim of the invention is to provide a particle detection unit (100) which reliably prevents the gradual dirtying of the optical components. This is achieved by a dirt-reducing flow-guiding component (150) for deflecting a fluid flow (F) entering via the flow inlet (121) in the direction of the flow outlet (122), wherein the flow-guiding component (150) is positioned within the detection chamber (120) in the region of the fluid flow (F) between the flow inlet (121) and the flow outlet (122), but outside of the detection region (DB).

Description

[0001] Changed description for late registration

[0002] Particle detection unit with detection chamber and flow guide component

[0003] The invention relates to a particle detection unit designed for use with an intake particle detection system, for example, for fire detection. The particle detection unit comprises a housing with a detection chamber arranged therein and shielded from ambient light. The detection chamber comprises a flow inlet for the entry of a fluid flow and a flow outlet for the exit of the fluid flow. It also comprises a light transmitter and a light receiver aligned with one another such that a detection area for detecting particles contained in the fluid flow is defined by the superposition of the light emitted by the light transmitter and the incidence area of ​​the light receiver within the detection chamber.

[0004] Particle detection units are often used for fire detection, particularly in buildings, vehicles, on ships, etc., whereby particles contained in the ambient air of a monitored area, e.g. smoke particles or aerosols, which indicate a fire or its origin, are detected by the particle detection unit. A monitored area is usually an area to be monitored in which people are present, (valuable) goods are stored, and / or there is an increased fire risk. Monitoring areas can be parts of a building, such as rooms, storage rooms, or server rooms; parts of a vehicle, e.g. a ship, train, bus, or aircraft, such as passenger compartments or engine rooms; but also an area in the immediate vicinity or within an object, such as a machine or a control cabinet.

[0005] To detect particles, the detection chamber, which is in fluid communication with the ambient air, is located inside the housing of the particle detection unit. The actual detection range, within which particles transported into the detection chamber with the ambient air can be detected, is usually defined by the superposition of the light from the light transmitter and the incidence range of the light receiver within the detection chamber. During detection, the particles are illuminated by the light beams emitted by the light transmitter and can be detected by the light receiver either based on the transmitted light reduced by the particles (transmitted light detector) or based on the scattered light scattered by the particles (scattered light detector). To ensure that only the light emitted by the light transmitter reaches the particles in the detection range, the detection chamber is shielded from ambient light.

[0006] A well-known application for the use of particle detection units is aspirating smoke detectors, also known as aspirating particle detection systems. A scattered light detector for such aspirating particle detection system is known, for example, from European patent EP 1 709 428 B1. The scattered light detector comprises a light source and a scattered light receiver, which are arranged together within a housing with an inlet opening and an outlet opening. Between the two openings, the carrier medium, usually ambient air, flows through the housing along a flow path. In order to shield the detection chamber delimited by the housing as completely as possible from ambient light, it is proposed to design a flow channel guiding the flow path with two bends, one bend before and one bend after the detection area, referred to here as the scattered light center.The bends act as light traps and prevent external light from entering the detection chamber. Furthermore, a total of three apertures are arranged inside the housing, each designed as a straight wall. These shield the light receiver from the light emitted by the light source, ensuring that only the scattered light scattered by particles in the detection area reaches the light receiver's incident field.

[0007] The intake particle detection system also comprises at least one pipe and / or hose line, which leads into one or more monitoring areas via one or more intake openings for the respective collection of a fluid sample, in particular an air sample. Multiple monitoring areas can be arranged, for example, in different areas of the same space, such as a (large) warehouse, but also in individual rooms of a building or sections of a vehicle, such as the passenger cabins of a ship. The extracted fluid samples are transported along the pipe and / or hose line to the particle detection unit and introduced into the detection chamber by connecting the pipe and / or hose line to its inlet opening.A problem typically encountered with intake particle detection systems is that the air continuously drawn in and introduced into the detection chamber, even when there is no fire, contains particles and / or aerosols such as dust, dirt, etc., which, over longer periods of operation, lead to contamination of the optical components and thus to a decrease in detection performance.

[0008] Such an aspirational fire detection system with two pipelines and a base unit, referred to here as an aspirating smoke detection device, is known from the prior art, namely the published patent applications EP 4 099 285 A1 and EP 4 099 286 A1. The base unit comprises a printed circuit board (PCB) and a so-called distributor, which enables the modular use of either one or two sensor heads. Particle detection units based on the scattered light principle, for example, are to be used as sensor heads. During operation, the fan located in the fan housing of the base unit creates a negative pressure, so that air is sucked along the pipelines first into the base unit and then into the respective detection chamber of the sensor head housing. The sucked-in air can escape back into the environment via an outlet in the fan housing.A filter is also used to filter out dirt and dust from the air drawn in through the inlets of the sensor head housings. To ensure that any smoke particles required for fire detection continue to reach the sensor heads in sufficient quantities, such a coarse filter only filters out larger dirt or dust particles. Fine dust particles or aerosols contained in the drawn-in air can also lead to gradual contamination of the optical components, particularly the light transmitter and light receiver.

[0009] A similar suction particle detection system for fire detection with multiple sampling lines is also known from WO 97 / 42486 A1. The sampling lines lead to an inlet manifold of a common base unit, which also includes a suction device, a filter, and a smoke detector in the form of a particle detection unit. The suction device generates a flow, whereby air is sucked in via the sampling lines, coarsely filtered in the filter, and fed to the smoke detector for detecting any smoke particles contained therein. The smoke detector comprises a cylindrical detection chamber, in one end of which a light transmitter, namely a laser diode for generating a light beam penetrating the detection chamber in the axial direction, and in the other end of which a light absorber is arranged to absorb the light beam.A flow inlet and a flow outlet of the detection chamber are arranged opposite each other on its outer surface, so that the air drawn in via the sampling lines enters the cylindrical detection chamber radially and flows through the light beam without further deflection, exiting radially again on the opposite side. For particle detection, a photodetector is also positioned within the detection chamber, forming a scattered light angle with the light beam, so that light beams scattered by smoke particles contained in the air there can be detected.

[0010] To prevent fine dirt and / or dust particles still contained in the air flow continuously drawn in and fed into the detection chamber after coarse filtration from reaching the optical components and causing contamination there, WO 97 / 42486 A1 also proposes a fine filter designed to remove as much of the particles as possible from a portion of the air drawn in via the sampling lines. This purified air is also blown into the detection chamber via separate inlets, specifically in the area of ​​the optical components there, such as the light transmitter, light absorber, and photodetector. This is intended to keep the coarsely filtered air flow, which is to be examined for particles, away from the optical components. The proposed solution is comparatively complicated to implement because several additional air nozzles must be provided on the detection chamber.In addition, the flow parameters with which the purified air is blown into the detection chamber must be precisely adjusted and continuously adjusted in order not to impair the air flow of the coarsely filtered air required for particle detection.

[0011] In addition to the use of filters, it is also known to influence the flow parameters of particle-laden flows, for example, using so-called particle separators, in order to reduce the amount of particles contained in the fluid flow or to separate specific particles from the fluid flow. A particle separator utilizes the mass or inertia of the particles contained in the flow, whereby the path of the particles carried in the flow can be influenced by changing the flow parameters, such as the inflow and outflow angle, flow velocity, flow direction, the creation of turbulent or laminar regions, etc. Well-known technical implementations include centrifugal separators, particularly cyclones, in which the flow is set into rotation, and so-called inertial separators, in which the flow is deflected.

[0012] International Patent Application WO 2010 / 100549 discloses several implementations of a so-called branching chamber, which is intended to separate a portion of the particles contained in the air sucked in via an aspiration fire alarm system, so that only the portion containing the desired target particles reaches the measuring chamber of the detection unit, preventing contamination of the optical components by the other portion. In one implementation, the branching chamber is designed as a cyclone, so that particle separation occurs through centrifugal forces. In another implementation, particle separation is to be brought about by accelerating the flow and subsequent deceleration. The sucked-in air is introduced into the branching chamber via an inlet duct. The inlet duct is designed as a nozzle, with a cross-section that tapers towards the branching chamber, so that the air flowing into the branching chamber is initially accelerated.Due to the increased cross-section of the branching chamber, the airflow velocity subsequently decreases again, with the larger particles being subjected to less deceleration than the smaller particles. Consequently, the smaller particles are more easily deflected and are guided via a branching duct to the flow inlet of the detection chamber. The branching duct is approximately circular in shape, with rounded transitions intended to prevent air turbulence and pressure losses. The disadvantages of the proposed implementations are the high design complexity and space requirements within the basic unit, which must accommodate not only the fan and the particle detection unit, but also the branching chamber.

[0013] An aerosol photometer for the quantitative determination of aerosol particles contained in the measurement volume is described in more detail in the German patent application DE 10 2017 001 436 A1. The photometer operates according to the scattered light principle; accordingly, the light source and light receiver are aligned to each other, enclosing a scattered light angle. The gas flow containing the aerosol to be measured is generated by a conveying device and flows in a straight line between the light source and the light receiver, crossing the measurement volume there. Especially during long operating times, the probability of contamination of the optical components by aerosol deposits is high, which can lead to erroneous measurements. To avoid such deposits, the flow rate of the conveying device should be varied during operation. Accordingly, the flow rate is reduced for high mass concentrations.However, such a solution is not suitable for continuous fire monitoring, where the mass concentration of the air drawn in for monitoring is unknown. An increased mass concentration of, for example, smoke particles is present precisely in the fire to be detected and therefore acts as the fire parameter to be detected. US patent US 9,075,007 B2 discloses an aspirating smoke detector with an aspirating fan, an optical detection chamber module, and an air duct leading into the detection chamber module. In order to be able to use the aspirating smoke detector in environments with particularly high particle concentrations, such as in mining, some of the dust particles contained in the drawn-in air are to be separated before the air enters the detection module. For this purpose, the air duct is U-shaped, configured with 90° bends.The sudden change in flow direction is intended to ensure that heavier particles separate from the airflow and collect in a dedicated dust chamber. This solution also requires a lot of space, as both the U-shaped air duct and the dust chamber must be housed within the base unit.

[0014] Influencing the flow parameters of fluid flows through internal components such as baffles or spoilers is known from other technical fields. For example, German patent application DE 10 2020 114 720 A1 discloses a separation device for a cyclone vacuum cleaner in which, during suction operation, air laden with suction material is sucked into the cylindrical separation drum through a suction nozzle. Suction material particles contained in the particle air stream are separated in the circumferential direction of the separation drum, and the particle air stream then leaves the separation drum tangentially. A spoiler designed as a baffle is also provided at the particle outlet path. This spoiler at least partially covers the container opening of a coarse material collection container and is thus intended to influence the separation mechanism of particles and air. The orientation or angle of the spoiler is intended to control the flow parameters of the particle air stream and thus the separation rate.

[0015] The overall disadvantage of separating or filtering out particles contained in air samples under investigation is that their concentration or quantity is reduced. For the use of particle detection units, particularly for fire detection, this not only increases the detection threshold but also reduces the detection sensitivity. This means that the concentration required to detect smoke particles increases, which means that fires can only be detected later. Many of the solutions described in the prior art are also complex to construct and / or require a lot of space.

[0016] It is the object of the present invention to eliminate the disadvantages of the prior art and to provide a particle detection unit which is designed for use with an intake particle detection system and which reliably prevents gradual contamination of the optical components, in particular of the light transmitter and the light receiver, with only minimal design effort, with little space requirement and at the same time with high detection accuracy.

[0017] The object is achieved by a particle detection unit designed for use with an intake particle detection system according to claim 1.

[0018] A particle detection unit of the type described in more detail above is characterized in that the particle detection unit has at least one, in particular a contamination-reducing, flow-guiding component for redirecting a fluid flow entering via the flow inlet toward the flow outlet. The flow-guiding component is positioned within the detection chamber in the fluid flow region, between the flow inlet and the flow outlet, but outside the detection region.

[0019] Unlike the prior art, according to which contamination-reducing means such as separators or filters, which separate or filter out a portion of the particles contained in the fluid flow, are arranged outside the detection chamber, according to the present invention, the contamination-reducing flow-guiding component is located within the detection chamber. Contamination of the optical components, in particular the light transmitter and the light receiver, is not prevented by reducing the amount of particles entering the detection chamber, but rather by redirecting the fluid flow flowing in via the flow inlet toward the flow outlet. The flow-guiding component shields the optical components from direct flow, thereby preventing the accumulation of particles entrained in the fluid flow, particularly in the area of ​​the light transmitter and / or the light receiver.This in turn prevents contamination and ultimately increases the time intervals between required maintenance work and the operating time of the particle detection unit.

[0020] The fluid flow should be guided "past" the optical components as unhindered as possible so that particles carried into the detection chamber with the fluid flow are also transported out of the detection chamber again via the flow outlet. For this purpose, the flow guide component is preferably designed with a single, continuous fluid guide surface that is flat, in particular free of corners or edges, i.e. without internal edges, corners, joints, burrs or the like. This prevents deposition and / or accumulation of particles carried along in the fluid flow flowing along the fluid guide surface. In order not to hinder the function of the particle detection itself, i.e. to enable the unhindered detection of scattered light or transmitted light by the light receiver, the flow guide component is positioned outside the detection area.

[0021] The solution according to the invention reduces the accumulation of particles throughout the detection chamber, and in particular in the area of ​​the light transmitter and / or the light receiver and / or (other) optical components, without reducing the concentration or quantity of particles to be detected in the fluid flow, such as smoke particles or smoke aerosols, in a way that affects detection accuracy. According to an advantageous embodiment of the invention, the flow-guiding component is designed with at least one curved fluid-guiding surface directed toward the flow inlet and / or the flow outlet.

[0022] For example, the flow-guiding component can be designed as a curved inner wall of the detection chamber, in particular one with a cross-sectional profile in the form of a ring segment. The curved inner surface, which follows the inner radius of the ring segment, then points in the direction of the flow inlet and / or the flow outlet and functions as a fluid guide surface, so that a fluid flow entering the detection chamber via the flow inlet flows against this fluid guide surface in an inflow direction, is deflected by its curvature, and flows away from the fluid guide surface in an outflow direction, toward the flow outlet. For example, the radius of the curvature lies in a range between 4 mm and 8 mm and is preferably approximately 6 mm.

[0023] In an exemplary development, the curved fluid guide surface of the flow guide component further comprises a leading edge pointing in the direction of the flow inlet and / or a trailing edge pointing in the direction of the flow outlet. The leading and / or trailing edges are preferably located on the outside or delimit the fluid guide surface in the inflow and outflow directions, so that the latter follows a smooth, flat, and curved profile.

[0024] Preferably, the leading and / or trailing edges are structurally separated from the curved fluid guide surface of the flow guide component and have respective fluid guide surfaces that follow a straight course. The trailing edge, in particular, can significantly contribute to influencing the flow parameters. For example, a so-called flow separation can be generated at the trailing edge, in which the fluid flow detaches from the curved fluid guide surface, resulting in regions outside the main flow with significantly reduced flow velocity and / or turbulence and / or flow directions deviating from the direction of the main flow. In an exemplary embodiment, the angle of the leading and / or trailing edges lies in a range between 35° and 55° and is preferably approximately 45°.

[0025] Preferably, the light transmitter and / or the light receiver are positioned in such an area, i.e. outside the main flow following the outflow direction, whereby the particles carried primarily in the main flow are transported past the light transmitter and / or the light receiver and out of the detection chamber.

[0026] According to a variant of the invention, it is particularly advantageous that the light transmitter and / or the light receiver are arranged within respective dead zones which are formed by deflecting the fluid flow by means of the flow guide component within the detection chamber.

[0027] Dead zones are defined as areas outside the main flow with significantly reduced flow velocity and / or turbulence and / or flow directions deviating from the main flow, which are preferably delimited by structural limitations such as fixtures or walls of the detection chamber. Such dead zones can therefore be created at specific positions within the detection chamber by the geometry of the detection chamber and / or the flow guide component interacting with the fluid flow.

[0028] For example, the flow-guiding component can be positioned upstream of the light emitter, thereby redirecting the fluid flow and directing its main flow past the light emitter. The light emitter is located in the "flow shadow" or leeward zone, i.e., an area with a significantly reduced flow velocity compared to the main flow. This area is, in turn, delimited by corresponding inner walls of the detection chamber, so that the accumulation of the inflowing fluid creates a kind of "air cushion" or counterflow, which reduces the entry and consequently also the accumulation of particles contained in the fluid flow within the thus formed dead zone. Due to the significantly higher flow velocity, the particles largely remain in the main flow and are transported out of the detection chamber via the flow outlet.

[0029] According to a variant of the invention, the flow inlet and the flow outlet are connected by a flow channel that penetrates the detection area and is defined by fluid guide surfaces that direct the fluid flow. The fluid guide surfaces do not necessarily have to completely define the flow channel; partial or region-specific definition is also conceivable. In this case, the detection chamber within the particle detection unit is defined by the fluid guide surfaces of the flow channel, or the flow channel corresponds to the detection chamber. To reduce the accumulation of particles and thus of contaminants in the flow channel or in the detection chamber, the flow channel can have a round, approximately circular, or even a square flow cross-section with rounded corners.

[0030] In an exemplary variant, the flow channel can be designed to follow an approximately U-shaped course from the flow inlet to the flow outlet, whereby a fluid flow entering at the flow inlet is deflected by approximately 180° and guided in the direction of the flow outlet. By having one or more outer fluid guide surfaces, i.e. those located on the outer radius of the U-shaped course, and one or more inner fluid guide surfaces, i.e. those located on the inner radius of the U-shaped course, curved or bent, in particular by having a radius of curvature, the flow resistance within the flow channel can be reduced. Preferably, the cross-section along the entire flow channel is almost identical and corresponds to the diameter of an intake pipe, which not only further reduces the flow resistance but also the power consumption and noise generation of the fan.The fluid flow can then flow unhindered through the flow channel from the flow inlet to the flow outlet at as constant a velocity as possible. This prevents particle accumulation within the detection chamber and ensures that the majority of the particles carried into the detection chamber by the fluid flow are also transported out of the detection chamber unhindered.

[0031] Depending on the layout of the pipe and / or hose system of an intake particle detection system connected to the particle detection unit, typical flow velocities at the flow inlet of the particle detection unit are in the range of approximately 1 m / s to 4 m / s. The geometry of the flow guide component and / or the flow channel are preferably designed for this entire flow velocity range, so that the accumulation of particles in the area of ​​the light transmitter and / or the light receiver is significantly reduced across the entire flow velocity range.

[0032] The exact geometry of the flow guide component and / or the flow channel can be determined using flow simulations, whereby the flow velocity of the main flow is set within the above velocity range. The simulations can then be carried out for different geometries, and the resulting flow profiles evaluated. The relationship between the flow profile, in particular the flow velocities and directions present in individual areas, and the degree of contamination caused by particle deposits can be determined experimentally. Two predominant effects become apparent. Firstly, almost no particles can be detected within dead zones, i.e., areas with significantly reduced flow velocity and deviating flow direction, thereby significantly reducing contamination of the optical components located therein.On the other hand, the constantly fast flow velocity in the area of ​​the main flow prevents particles from accumulating on the walls there.

[0033] Similarly to what has already been described in connection with the flow-guiding component, the fluid guide surfaces of the flow channel, in particular the curved fluid guide surfaces located on the outer radius, can also have a leading edge and / or a trailing edge. Particularly at the trailing edge, a flow separation can be created, and consequently, outside the main flow, a region with a significantly reduced flow velocity and / or flow directions deviating from the direction of the main flow can be created, with the main flow itself continuing as laminarly as possible and at a constant velocity. Optical components, in particular the light transmitter and / or the light receiver, can then be positioned in the region of the significantly reduced flow velocity.

[0034] In a further development of the previously described variants, the flow inlet and flow outlet are arranged adjacent to each other on the same side of the housing of the particle detection unit. In a scattered light configuration, the light transmitter can then be located approximately opposite the flow inlet and the light receiver approximately opposite the flow outlet (or vice versa). The light transmitter and light receiver enclose the scattered light angle specific for the detection of one or more specific particle types.

[0035] It is advantageous if the flow inlet is located on the first leg, the flow outlet on the second leg, and the light transmitter, light receiver, and flow guide component are arranged in the intermediate, central region of the approximately U-shaped flow channel. The flow guide component, or its curved fluid guide surface, can then function as part of the flow channel.

[0036] Advantageously, the inner and outer fluid guide surfaces of the flow channel can interact with the flow guide component in order to guide the fluid flow flowing through the flow channel past the light transmitter and / or light receiver and thus to avoid an accumulation of particles contained therein in the interior of the detection chamber, in particular in the region of the light transmitter and / or the light receiver.

[0037] In an optional embodiment of the invention, the particle detection unit is configured as a scattered light detector, wherein the light transmitter and the light receiver are aligned to include a scattered light angle with each other, and the flow guide component is positioned between the light transmitter and the light receiver, but outside the light emitted by the light transmitter and outside the incidence area of ​​the light receiver.

[0038] In order to protect the light receiver from unwanted light, which is reflected, for example, on the inside surfaces of the housing or, in the case of a scattered light configuration, can come directly from the light transmitter, according to an exemplary variant of the invention the particle detection unit has a diaphragm in the area of ​​the light transmitter and / or in the area of ​​the light receiver, which shields the light receiver from the light transmitted by the light transmitter and in particular not scattered by particles located in the detection area.

[0039] The aperture can, for example, be designed as an inner wall of the detection chamber having a recess or opening, which is arranged directly in front of the light transmitter and / or the light receiver. The range of the light emitted by the light transmitter and the incidence range of the light receiver are then limited, among other things, by the geometry of the recess or opening. In order not to unnecessarily influence the light path and thus disrupt the detection performance, the recess or opening of the aperture is preferably "open", i.e. not closed by window glass, lenses, or other components with a density different from the ambient air. Consequently, the light transmitter and / or the light receiver are fluidly connected to the detection chamber.

[0040] According to a preferred example of the invention, the particle detection unit has a diaphragm in the area of ​​the light transmitter and / or the light receiver. This diaphragm is double-walled and has a recess or opening extending through the respective wall to prevent particles contained in the fluid flow from accumulating in the area of ​​the light transmitter and / or the light receiver. The double-walled design significantly reduces particle ingress to the light transmitter and / or the light receiver. The front wall of the diaphragm, which is oriented toward the detection chamber or the fluid flow therein, can optionally function as an additional fluid guide surface.

[0041] According to another embodiment, the particle detection unit comprises an upper shell and a lower shell jointly forming the housing, wherein respective components, in particular the at least one flow guiding component and / or the fluid guiding surfaces delimiting the flow channel and / or the apertures arranged in the region of the light transmitter and / or the light receiver, are designed in two parts, formed jointly by the upper shell and the lower shell.

[0042] Alternatively or optionally, the particle detection unit can be manufactured as a one-piece injection-molded part, in particular in one piece with the at least one flow-guiding component, the fluid guide surfaces defining the flow channel, and / or the apertures arranged in the area of ​​the light transmitter and / or the light receiver. If the housing is designed in two parts, i.e., with an upper and lower shell, the upper and lower shells are each manufactured in one piece using the injection molding process.

[0043] Further details, features, feature (sub)combinations, advantages and effects based on the invention will become apparent from the following description of a preferred embodiment of the invention and the drawings. These show in

[0044] Fig. 1 is a perspective view of an exemplary embodiment of the inventive

[0045] Particle detection unit with a flow guide component,

[0046] Fig. 2 shows a section of Figure 1 showing the flow guide component in a single view,

[0047] Fig. 3 is a view of the particle detection unit from Figure 1, from above and with fluid flow indicated schematically by arrows, and Fig. 4 is a schematic representation of the flow profile within the detection chamber of a particle detection unit according to Figure 3.

[0048] The figures are merely exemplary and serve only to clarify the invention. The same elements are designated by the same reference numerals.

[0049] Figure 1 shows a perspective view of an exemplary embodiment of the particle detection unit 100 according to the invention. In this embodiment, the housing 110 of the particle detection unit 100 is designed in two parts, with a lower shell and an upper shell. Only the upper shell is shown here to allow a view into the interior of the housing 110. The housing 110 delimits a detection chamber 120 arranged therein and shielded from ambient light, which includes a flow inlet 121 and a flow outlet 122. The flow inlet 121 and the flow outlet 122 are arranged adjacent to one another on a common side, namely the front side 111 of the housing 110.The flow inlet 121 and the flow outlet 122 are fluidically connected to one another by the detection chamber 120, so that a fluid flow F, schematically indicated by the arrows shown, can enter the detection chamber 120 via the flow inlet 121 and exit the detection chamber 120 via the flow outlet 122.

[0050] In the presently illustrated embodiment, the detection chamber 120 is constructed as an approximately U-shaped flow channel 120 defined by fluid guide surfaces. Some of the fluid guide surfaces follow a straight path; moreover, the flow channel comprises several curved outer fluid guide surfaces 123 located on the outer radius of the U-shaped path, and several curved inner fluid guide surfaces 124 located on the inner radius of the U-shaped path. The curved fluid guide surfaces 123, 124 not only contribute to guiding the fluid flow F, but also to influencing the flow resistance, with a constant, large radius causing a slow change of direction with low flow resistance. By avoiding edges in the flow cross-section, the accumulation of particles contained in the fluid flow F in the region of the flow channel 120 is reduced.

[0051] The flow inlet 121 connects to the first leg, and the flow outlet 122 connects to the second leg. The optical components required for particle detection, the light transmitter 130 and the light receiver 140, are located in the intermediate, central region of the U-shaped path. In the simplest case, the light transmitter 130 and the light receiver 140 can be, for example, a single light-emitting diode (LED) and a single photodiode (PD). In the exemplary embodiment shown here, additional optical components in the form of respective prisms and lenses are included, which influence the light path and thus facilitate the definition of the detection area DB by superimposing the light emitted by the light transmitter 130 and the incidence area of ​​the light receiver 140 (see also Figure 3) within the detection chamber or flow channel 120. An aperture 160 is arranged directly in front of the light transmitter 130 and the light receiver 140.The aperture 160 is through an inner wall of the detection chamber.

[0052] 120, wherein a recess or opening 161 allows light coming from the light transmitter 130 or leading to the light receiver 140 to pass through unhindered. The aperture 160 positioned in front of the light transmitter 130 is double-walled, with an additional wall 162 facing the detection chamber 120 and positioned at the front in the direction of flow, which can function as an additional fluid guide surface and reduces contamination.

[0053] The light transmitter 130 is located approximately opposite the flow inlet 121 and the light receiver 140 is located approximately opposite the flow outlet 122, so that a fluid flow F flowing into the detection chamber 120 via the flow inlet 121 flows through the detection area DB before leaving the detection chamber 120 via the flow outlet 122. Between the light transmitter 130 and the light receiver 140, but outside the detection area DB, there is a deflection device for the fluid flow from the flow inlet 121.

[0054] 121 in the direction of the flow outlet 122, a flow guide component 150. Preferably, the previously described components, with the exception of the light transmitter 130 and the light receiver 140, are manufactured in one piece with the particle detection unit 100 by injection molding.

[0055] Figure 2 shows the area of ​​the detection chamber 120 marked with a circle in Figure 1 in a perspective section, in which the flow-guiding component 150 is shown in a single view. For example, and as also shown here, the flow-guiding component 150 is constructed as a curved inner wall of the detection chamber 120 and has a cross-sectional profile in the form of a ring segment. The curved inner surface, following the inner radius of the ring segment, points toward the flow inlet 121 and the flow outlet 122 to function as a curved fluid guide surface 153 for deflecting the fluid flow F.In the inflow direction, i.e. in the direction of the fluid flow F flowing towards the curved fluid guide surface 153, the flow guide component 150 has a leading edge 151 with a straight fluid guide surface, and correspondingly in the outflow direction, i.e. in the direction of the fluid flow F flowing away from the curved fluid guide surface 153, a trailing edge 152, likewise with a straight fluid guide surface.

[0056] Figure 3 shows a top view of the particle detection unit 100 from Figure 1. This view particularly clearly shows the geometry of the previously described individual components of the particle detection unit 100 and their arrangement and alignment relative to one another. The fluid flow F, in particular the course of the main flow, is again schematically indicated by arrows inserted in Figure 3. The fluid flow F enters the detection chamber or flow channel 120 via the flow inlet 121 and, after flowing through the detection region DB, exits the flow channel 120 via the flow outlet 122. The deflection of the fluid flow F is primarily achieved by the flow guide component 150 or its curved fluid guide surface 153 and the curved, outer fluid guide surfaces 123 located on the outer radius of the U-shaped flow channel 120.The flow-guiding component 150 is arranged in the flow direction of the fluid flow F behind the light receiver 140 and upstream of the light transmitter 130, but outside the detection area DB, in an area with a trapezoidal geometry that is slightly recessed from the flow channel 120. Two of the surfaces or walls delimiting the trapezoidal area are formed by the apertures 160 positioned directly in front of the light transmitter 130 and the light receiver 140, respectively. This ensures that the fluid flow F can flow through the detection area DB, and that the flow-guiding component 150 is simultaneously positioned outside the light emitted by the light transmitter 130 and the incident area of ​​the light receiver 140, so as not to impair the detection of particles contained in the fluid flow F and transported into the detection area DB.

[0057] In the flow direction immediately upstream of the light receiver 140, the flow channel 120 comprises an outer, curved fluid guide surface 123 whose course ends in a trailing edge 125. The fluid flow F is guided along the outer, curved fluid guide surface 123 so that its main flow path leads past the light receiver 140. At the trailing edge 125, the fluid flow F breaks off, thus detaching itself from the curved fluid guide surface 123, so that adjacent to the trailing edge 125 and lying outside the main flow, a region with significantly reduced flow velocity and / or turbulence and / or a flow direction deviating from the direction of the main flow results. This region is delimited by the geometry of the inner walls of the detection chamber 120, in particular by the aperture 160 arranged upstream of the light receiver 140. The light receiver 140 is arranged within the dead zone T defined in this way (see Figure 4).A corresponding function is assigned to the flow-guiding component 150 arranged directly upstream of the light transmitter 130 in the flow direction of the fluid flow F, or rather, its curved fluid-guiding surface 153 and its trailing edge 152, so that the light transmitter 130 is also arranged within a dead zone T (see also Figure 4) delimited by the adjacent geometry, in particular by the aperture 160. The leading edge 151 of the flow-guiding component 150 is intended to promote a defined flow onto the curved fluid-guiding surface 153 and is aligned accordingly with the flow direction. Finally, Figure 4 shows a schematically illustrated course of the flow profile within the detection chamber 120 of a particle detection unit 100 according to Figure 3. The illustrated flow channel section is limited to the central region of the U-shaped flow channel 120 located between the two legs.The flow profile shown for the given geometry can be determined, for example, using flow simulations. The underlying flow velocity at which the fluid flow F enters the flow channel 120 via the flow inlet 121 ranges between 1 m / s and 4 m / s in the typical application range of intake particle detection systems and is, for example, approximately 1.5 m / s here. Along the main flow H, which runs from the flow inlet 121, following the course of the U-shaped flow channel 120, to the flow outlet 122, the flow velocity is approximately constant and is, for example, approximately 1.5 m / s.At the trailing edge 125 located directly upstream of the light receiver 140 in the direction of the main flow H, the main flow H separates from the outer, curved fluid guide surface 123 of the flow channel 120, creating a region outside the main flow H with a deviating flow direction and a significantly reduced flow velocity. This region is delimited by the geometry of the inner walls of the detection chamber 120 there, in particular by the aperture 160 arranged upstream of the light receiver 140 for defining a first dead zone T. The flow velocity within the first dead zone T is only a fraction, e.g., at most one-third or at most one-tenth of the flow velocity of the main flow, and can even approach zero in certain regions or at times, particularly immediately upstream of the aperture 160.Within the dead zone T, the inflowing fluid accumulates, creating a kind of "air cushion" L that counteracts the inflow of further fluid. This effect is amplified by turbulence occurring within the dead zone T, which in turn generates countercurrents G leading out of the dead zone T.

[0058] In a corresponding manner, a second dead zone T is created at the trailing edge 152 of the flow-guiding component 150, which interacts with the front wall 162 of the aperture 160 arranged in front of the light transmitter 130, so that the fluid is guided past the light transmitter 130 along the main flow H. Outside the main flow H, the second dead zone T lies in the "flow shadow" or lee of the flow-guiding component 150, whereby the flow velocities present therein are considerably reduced and amount to only a fraction, for example, at most one-third or at most one-tenth of the flow velocity of the main flow, and can even approach zero in certain areas or at times, particularly immediately in front of the aperture 160. Within the second dead zone T, "air cushions" L caused by the accumulation of the inflowing fluid, as well as countercurrents G generated by turbulence, which counteract the inflow of further fluid, also arise.The curved fluid guide surface 153 of the flow guide component 150 serves, on the one hand, to guide and deflect the main flow H coming from the outer, curved fluid guide surface 123 and, on the other hand, to feed the fluid flowing from the first dead zone T back to the main flow H. The leading edge 151 of the flow guide component 150 promotes a defined flow onto the curved fluid guide surface 153 and is aligned accordingly to the flow direction.

[0059] The relationship between the flow profile shown in Figure 4, particularly the flow velocities and directions present in individual areas, and the degree of contamination caused by particle deposits can be determined experimentally. Two predominant effects are evident. First, almost no particles can be detected within the dead zones T, with significantly reduced flow velocities and deviating flow directions, thereby significantly reducing contamination of the optical components located there. Second, the constant, rapid flow velocity in the main flow area prevents particles from accumulating on the walls there.

[0060] List of reference symbols

[0061] 100 particle detection unit

[0062] 110 Housing 111 Front

[0063] 120 Detection chamber / flow channel

[0064] 121 Flow inlet

[0065] 122 Flow outlet

[0066] 123 curved, outer fluid guide surface of the flow channel

[0067] 124 curved, inner fluid guide surface of the flow channel

[0068] 125 Trailing edge of the flow channel

[0069] 130 light transmitters

[0070] 140 light receivers

[0071] 150 Flow control component

[0072] 151 Leading edge of the flow guide component

[0073] 152 Trailing edge of the flow guide component

[0074] 153 curved fluid guide surface of the flow guide component

[0075] 160 aperture

[0076] 161 Recess or opening

[0077] 162 front wall

[0078] DB detection range

[0079] F Fluid flow

[0080] G Countercurrent

[0081] H Main current

[0082] L air cushion

[0083] T dead zone

[0084] M:\Mdt AZ\W\0071 WAGNER Group GmbH\W071-049 P WO_Spoiler element as flow deflection means\W071-049 P WO official part\24-09-27_Registration folder ed\W071-049 P WO_changed description subsequent registration (RELEASE) pure docx

Claims

Patent claims:

1. Particle detection unit (100) designed for use with an intake particle detection system, in particular for fire detection, wherein the particle detection unit (100) has a housing (110) with a detection chamber (120) arranged therein and shielded from ambient light, which comprises a flow inlet (121) for the entry of a fluid flow (F) and a flow outlet (122) for the exit of the fluid flow (F), as well as a light transmitter (130) and a light receiver (140) which are aligned with one another such that a detection area (DB) for detecting particles contained in the fluid flow (F) is defined by superimposing the light emitted by the light transmitter (130) and the incidence area of ​​the light receiver (140) within the detection chamber (120), characterized in thatthat the particle detection unit (100) has at least one flow guide component (150) for deflecting a fluid flow (F) entering via the flow inlet (121) in the direction of the flow outlet (122), wherein the flow guide component (150) is positioned within the detection chamber (120) in the region of the fluid flow (F), between the flow inlet (121) and the flow outlet (122), but outside the detection region (DB).

2. Particle detection unit (100) according to claim 1, characterized in that the flow guiding component (150) is formed with at least one curved fluid guiding surface (153) directed in the direction of the flow inlet (121) and / or the flow outlet (122).

3. Particle detection unit (100) according to claim 2, characterized in that the curved fluid guide surface (153) of the flow guide component (150) has a leading edge (151) pointing in the direction of the flow inlet (121) and / or has a trailing edge (152) pointing in the direction of the flow outlet (122).

4. Particle detection unit (100) according to one of the preceding claims, characterized in that the light transmitter (130) and / or the light receiver (140) are arranged within or adjacent to respective dead zones (T) which are formed by deflecting the fluid flow (F) by means of the flow guide component (150) within the detection chamber (120).

5. Particle detection unit according to claim 4, characterized in that the dead zones (T) are structurally limited by boundaries, such as built-in components or walls of the detection chamber (120).

6. Particle detection unit (100) according to one of the preceding claims, characterized in that the flow inlet (121) and the flow outlet (122) are conductively connected to one another by a flow channel (120) which passes through the detection area (DB) and is delimited by fluid guide surfaces (123, 124) for conducting the fluid flow (F).

7. Particle detection unit (100) according to claim 6, characterized in that the flow channel (120) is formed having one or more outer and inner, curved fluid guide surfaces (123, 124) following an approximately U-shaped course.

8. Particle detection unit (100) according to claim 7, characterized in that the flow inlet (121) and the flow outlet (122) are arranged adjacent to each other on the same side of the housing (110), and the light transmitter (130) is directed approximately in the direction of the flow inlet (121) and the Light receiver (140) is aligned approximately in the direction of the flow outlet (122).

9. Particle detection unit (100) according to one of claims 6 to 7, characterized in that the flow inlet (121) on the first leg, the flow outlet (122) on the second leg and the light transmitter (130), the light receiver (140) and the flow guide component (150) are arranged in the intermediate, central region of the approximately U-shaped flow channel (120).

10. Particle detection unit (100) according to one of claims 6 to 9, characterized in that the inner and / or outer fluid guide surfaces (123, 124) of the flow channel (120) interact with the flow guide component (150) in order to avoid the accumulation of particles contained in a fluid flow (F) flowing through the flow channel (120) within the detection chamber (120), in particular in the region of the light transmitter (130) and / or the light receiver (140).

11. Particle detection unit (100) according to one of the preceding claims, characterized in that the flow guide component (150) is positioned between the light transmitter (130) and the light receiver (140), but outside the light emitted by the light transmitter (130) and outside the incidence area of ​​the light receiver (140).

12. Particle detection unit (100) according to one of the preceding claims, characterized in that the particle detection unit (100) has a diaphragm (160) in the region of the light transmitter (130) and / or in the region of the light receiver (140), which shields the light receiver (140) from the light emitted by the light transmitter (130).

13. Particle detection unit (100) according to one of the preceding claims, characterized in that the particle detection unit (100) has a diaphragm (160) in the region of the light transmitter (130) and / or the light receiver (140), which diaphragm is double-walled with a recess or opening (161) passing through the respective wall in order to prevent deposits of particles contained in the fluid flow (F) in the region of the light transmitter (130) and / or the light receiver (140).

14. Particle detection unit (100) according to one of the preceding claims, characterized in that the particle detection unit (100) comprises an upper shell and a lower shell jointly forming the housing (110), wherein respective components, in particular the at least one flow guiding component (150) and / or the fluid guiding surfaces (123, 124) delimiting the flow channel (120) and / or the diaphragms (160) arranged in the region of the light transmitter (130) and / or the light receiver (140) are designed in two parts, formed jointly by the upper shell and the lower shell.

15. Particle detection unit (100) according to one of the preceding claims, characterized in that the particle detection unit (100) is manufactured as an injection-molded part, in particular in one piece with the at least one flow-guiding component (150), the fluid-guiding surfaces (123, 124) delimiting the flow channel (120) and / or the apertures (160) arranged in the region of the light transmitter (130) and / or the light receiver (140). M:\Mdt AZ\W\0071 WAGNER Group GmbH\W071-049 P WO_Spoiler element as flow deflection means\W071-049 P WO Official Part\24-09-27_Registration folder ed\W071-049 P WO_Claims (RELEASE) docx