Fire detector and device for monitoring

Abstract

The invention relates to a device and a fire detector that monitor their own surroundings for objects that could negatively affect the spread of smoke or gases. To detect these objects, waves are sent through an opening in a housing into a detection area in the surroundings, and this detection area is expanded by means of an opening structure.

Description

[0001] The invention relates to fire detectors that monitor their surroundings for the occurrence of fires, in particular by detecting smoke, and their own surroundings or their surroundings for objects that could negatively affect smoke detection. Such objects can shield a fire detector, especially a smoke detector, in such a way that no smoke or combustion gases reach the fire sensors and consequently cannot be detected. In other fire detectors, e.g., fire gas detectors, which react to other fire characteristics such as combustion gases, objects in the vicinity of the fire detectors can also impair their detection capability by shielding.

[0002] The invention also relates to a separate device for monitoring objects in the vicinity of the device, which can be retrofitted to existing fire detectors, for example.

[0003] Fire detectors, such as smoke detectors, are used to detect smoke and can detect it in various ways. Known smoke sensors are based on measurement principles such as ionization, extinction, and scattering. Smoke sensors are often combined with other sensors, such as gas sensors, flame sensors, and / or temperature sensors. Particularly for optical methods like extinction and scattering, it is known to arrange measuring sections or points within a detector housing in a measuring chamber and to allow smoke to enter through corresponding openings in the housing. It is also known to arrange the measuring sections or points outside the housing, which facilitates smoke entry into the measuring sections or points. In both cases, however, even with careful selection of the installation location, subsequent changes, e.g.,By placing furniture, stacking boxes, installing new walls or suspended ceilings, objects may appear in the vicinity of the smoke detector that can disrupt or even prevent the spread of smoke, so that smoke, heat and / or combustion gases do not reach or enter the smoke detector, or reach it with a delay, and as long as this is the case, they cannot be detected in time.

[0004] Against this background, EP1191496A1 proposes a scattered light smoke detector in which the scattering point of the light emitter and light receiver is located outside the detector, outdoors. The smoke detector also features an ultrasonic sensor that monitors the area around the scattering point. This allows it to detect whether a foreign object is present in the area around the smoke detector, which could potentially impair the airflow conditions for fire detection. The ultrasonic sensor is located on the front of the detector and is directed towards the scattering point below the smoke detector. EP1191496A1 does not specify the area around the scattering point within which objects can still be detected. Therefore, EP2043068A1 proposes a sensor that is sensitive to objects located to the side of the detector.This sensor is designed to be sensitive within an angular range around the detector's vertical axis, allowing for monitoring gaps of no more than 150°. This is achieved by two LEDs illuminating a conical reflector. The emitted light is then reflected laterally. A photodetector, positioned centrally to the reflector, detects the light reflected back across the cone by objects. The distance to the object is calculated from the time of flight. To meet the requirement of monitoring gaps smaller than 150°, it suffices for the sensor to have two detection cones, each covering an angular range of slightly more than 30° (e.g., 31°) and pointing in opposite directions (180° apart). Alternatively, a multitude of individual sensors are proposed, evenly distributed around the entire circumference of the detector and oriented laterally.These arrangements do not allow for the detection of objects below the detector.

[0005] Like EP1191496A1, DE 102006023048 proposes a smoke detector with a self-testing device. This smoke detector has at least two smoke ingress openings evenly distributed around its circumference. Each opening is checked for permeability by a distance sensor. This sensor checks whether the opening is clear and whether there are any objects in the area in front of the opening or in the vicinity of the smoke detector. This testing device can also detect objects located to the side of the detector, but it cannot detect objects directly below the detector.

[0006] To reliably monitor a hemispherical area around the detector, EP2320399 A1 proposes arranging three transmitters and receivers at regular angular intervals of 120° around the detector's circumference. These receivers are capable of detecting objects to the sides of the detector, and an additional transmitter and receiver is positioned on the underside of the detector to detect objects below it. The distance to the objects is determined from the signal travel time between sending and receiving a reflected signal.

[0007] German patent DE 10 2020 206 577 A1 refers to DIN SPEC 91388 and the test setup described therein for monitoring devices for detecting objects in the vicinity of smoke detectors. To detect boards (100 cm × 100 cm) arranged laterally and / or below the smoke detector at a distance of 50 cm, as specified in DIN SPEC 91388, it proposes a monitoring device with four time-of-flight sensors evenly spaced on a radial outer surface of the detector housing. Like the sensors in EP 2 043 068 A1, these sensors use the signal travel time for distance determination and have similar detection angles ranging from 15° to 40°. However, unlike those in EP 2 043 068 A1, these sensors are not oriented directly to the side, but rather at an angle downwards. The angle of inclination is specified as a function of the sensors' detection angle. Additionally, another sensor can be provided to detect the area below the detector.

[0008] From WO 2008 / 032982, a robot became known that uses an ultrasonic sensor to detect objects in its environment so that it can avoid them. The sensor's sound emission opening is designed on the front in the form of an oval or rectangular, elongated slot, so that the sensor has a wide horizontal field of view and a restricted vertical field of view.

[0009] German patent DE 10 2009 056 268 A1 describes a hazard detector with a device for detecting objects in the immediate vicinity of the detector using only one ultrasonic sensor. Several measures are proposed for this purpose. Firstly, the ultrasonic sensor can be mounted on an actuator that allows the sensor to be aligned in different directions, thus successively scanning the entire area around the detector, similar to radar. Alternatively, the ultrasonic transducer can be operated with a variable supply voltage, as increasing the supply voltage results in a larger elevation angle for the sensitive area. Additionally, the sensor is provided with a dome-shaped or diffusion cone-shaped sensor-active surface that covers the sensor and extends significantly beyond the rest of the hazard detector's housing.Because ultrasound waves are emitted from this housing surface in the direction of the normal, the ultrasound waves are emitted over the entire elevation angle range from 0° to 180°.

[0010] Korean patent KR 10 2007 0 071 203 A proposes an ultrasonic distance sensor that transmits at a frequency of 40 kHz and whose housing has a single sound outlet opening with a diameter of 4 mm. This is intended to increase the sensor's detection range compared to conventional ultrasonic distance sensors with a protective grid of concentric rings over the sound outlet. The protective grid of known conventional ultrasonic distance sensors does not extend the sensor's detection range.

[0011] EP 2 348 495 A1 also discloses a smoke detector with a device for detecting objects in the vicinity of the smoke detector using conventional ultrasonic distance sensors. For this purpose, ultrasound is emitted from three sensors evenly distributed around the circumference in the direction of the space below the detector. To enable the detection of objects to the sides of the detector, a portion of the ultrasound from each sensor is reflected laterally by a reflector, while the remaining portion is transmitted into the space below the detector. The reflectors create a sound shadow area within which no detection is possible.

[0012] Also described in EP 3 719 769 A1 is a smoke detector with an obstacle detector that uses a single ultrasonic sensor to detect objects in the vicinity of the detector. The ultrasonic sensor is located centrally on the front face of the detector housing, the side facing the monitoring room. The obstacle detector uses a cup-shaped guide element to reflect emitted ultrasonic waves radially relative to a longitudinal axis of the housing. The guide element, which can also be described as a shallow hollow cone, is mounted with its tip pointing towards the ultrasonic sensor and at a short distance from it. A ring is arranged around the circumference of the housing such that ultrasonic waves reflected by the guide element are directed under the ring and past the smoke inlet openings located in the cylindrical housing's outer surface.This allows the detector to recognize if the smoke entry openings have been covered. If the smoke entry openings, along with the ring, have been covered with tape, for example, the tape reflects the ultrasonic waves back to the ultrasonic sensor. No further influence of the smoke entry openings and the ring on the ultrasonic waves has been disclosed. The guide element can also act as a secondary sound source and transmit ultrasound into the area of ​​the room located below / above the detector.

[0013] The fire detectors and object detection devices known from the prior art either do not cover the entire area of ​​the room relevant for the spread of smoke, or the fire detectors use structures that extend far beyond the rest of the housing, use actuators to scan the room section by section, or they require a large number of sensors (at least four sensors) for environmental monitoring to detect objects in the entire area around the fire detector.

[0014] The invention is based on the objective of creating a fire detector and a device that ensures largely complete monitoring of the entire environment relevant to smoke propagation or the surroundings of a fire detector with as few sensors as possible.

[0015] This problem is solved by a fire detector according to claim 1 and a device according to claim 9.

[0016] Further advantageous embodiments are specified in dependent claims 2-8 and 10.

[0017] The fire detectors under consideration are preferably smoke detectors, smoke alarms, or smoke gas detectors. Such fire detectors often feature an optical detection unit operating on the light scattering principle for detecting smoke particles. The optical detection unit can be housed within the detector's casing, which has smoke inlet openings through which smoke to be detected can enter the casing and reach the optical detection unit. The detection unit preferably, but not necessarily, includes a labyrinth to shield against direct ambient light. Alternatively, the fire detector can also be an open smoke detector with a measuring volume located outside the casing in the open air. The fire detectors can alternatively or additionally include a gas sensor for detecting fire-related gases and other sensors, such as temperature and / or flame sensors.In the case of optical smoke detectors, the sensor system comprises at least one light transmitter and at least one light receiver. In extinction smoke detectors, the light transmitter and receiver are aligned so that the light from the transmitter is deflected directly, or possibly via reflectors, and reaches the receiver. In scattered light smoke detectors, the transmitter and receiver are positioned at an angle to each other such that the receiver cannot directly receive the light from the transmitter, but only when it is scattered by particles. Multiple scattered light detection zones with different angles can also be combined with each other and / or with extinction detection zones, whereby the transmitter and / or receiver can also be used together. It is also conceivable to use several different wavelengths in a single optical detection unit.

[0018] Furthermore, the fire detectors under consideration can be connected to a fire alarm control panel via a common detector line or line, particularly a two-wire line, for signal and / or data transmission. This panel also supplies the detectors with power. Alternatively or additionally, they can have an autonomous power supply, such as a battery, possibly in combination with a solar cell. Furthermore, such fire detectors can alternatively or additionally have a radio module for transmitting alarm messages, warning messages, maintenance information, operating data, condition data, or status information to a neighboring fire detector, a fire alarm control panel, or a gateway for forwarding to a service, e.g., via the internet (cloud). This information can, of course, also be transmitted via wired connections. It is also conceivable to temporarily store this data and, if necessary,to keep it accessible via a dedicated maintenance interface, in software and / or hardware, or to send it automatically at regular intervals via existing connections.

[0019] A fire detector according to the invention comprises a device for detecting objects in the vicinity of the fire detector. The fire detector has a housing with a mounting surface for at least indirect attachment to a mounting surface and a housing side facing the room, opposite the mounting surface. The detector can, for example, be mounted on a base that is attached to a ceiling. Alternatively, the fire detector can be recessed into the ceiling so that it is flush with the ceiling surface or protrudes only slightly above it. In certain situations, it is also conceivable to attach the fire detector to a wall, a door lintel, or a beam.

[0020] The object detection device comprises at least one sensor that transmits electromagnetic and / or acoustic waves with a wavelength λ through at least one wave-permeable opening in the room-facing housing of the fire detector along an axis into a detection area in the vicinity of the fire detector and receives the waves reflected by objects in the detection area through the same opening or, for example, in the case of a separate transmitter and receiver, through a further opening. According to the invention, the opening and / or the further opening has an opening structure with structural elements. The structural elements include at least one structural opening, preferably at least two structural openings, and, in the case of more than one structural opening, also the distances between the structural openings. In addition, refractive interfaces, e.g., in the form of lenses, can optionally be used as structural elements.The opening structure is designed such that it expands the sensor's detection range around the axis through diffraction effects or diffraction and refraction effects. Preferably, the opening structure is located within the room-facing side of the housing and is flush with this side. "Flush" in this context means that the opening structure is directly connected to the housing, including a slight offset, e.g., of 1-5 mm, from the surface of the room-facing housing and slight concave or convex curvatures.

[0021] The detection range is preferably expanded in such a way that the expanded detection range encompasses a complete hemisphere and objects in the hemisphere outside, especially below, the fire detector can be detected.

[0022] If the fire alarm is mounted on a ceiling, as is to be expected in most cases, the hemisphere is located below the fire alarm; if it is wall-mounted, it is located to the side.

[0023] Experiments have shown that diffraction effects alone can expand the detection range up to an elevation angle of 90° and beyond. Refraction effects can further enhance this expansion, for example, to achieve uniform sensitivity across the entire detection range. Refraction effects can be used in addition to or as an alternative to diffraction effects.

[0024] To expand the detection range through diffraction effects, aperture structures and / or openings with oval, rectangular, square, or circular shapes are suitable. Each aperture shape generates its own diffraction pattern, which depends on the wavelength λ used and its relationship to the respective aperture widths of the openings, and possibly also the spacing between multiple openings. The aperture structures are designed to expand the detection range largely uniformly around the axis across the entire azimuth range from 0° to 360°. However, it is also conceivable that the detection range has several preferred directions in which the expansion predominantly occurs. With a slit-shaped, long aperture structure, the detection range is expanded in only two directions.For structural openings, especially those that are perpendicular, intersecting, slit-shaped, or elongated, the detection area is expanded in four preferred directions. For round structural elements, especially circular and / or annular ones, the detection area is expanded in all directions around the axis. In all these cases, the expansion can occur over an elevation angle of 0° to at least 90°.

[0025] To achieve the most uniform possible expansion of the detection area around its axis, it has proven advantageous for the opening structure to include at least one circular aperture and / or at least one circumferential slit, in particular an annular slit or a circular ring aperture. If the opening structure includes both a circular aperture and an annular aperture or ring slit, it is advisable to arrange them concentrically. However, situations are also conceivable in which a slightly eccentric arrangement may be beneficial. For example, this is the case if the opening itself is not positioned centrally on the fire detector housing in order to achieve a concentric alignment of the detection area's sensitivity with respect to the fire detector. In this context, a slight deviation from a circular shape is also conceivable.The circumferential annular gap may also be interrupted by retaining ribs, which are necessary for mechanical reasons to maintain a distance between a circular aperture and the circumferential annular gap, as well as distances to any other annular gaps that may be present, and to form these gaps within the opening structure of the housing. Generally, a central arrangement of the sensor, the opening, and the opening structure relative to the housing is advisable. However, there may be situations where a central arrangement is not possible, for example, with a flat housing design, where the measuring chamber of a smoke detector is preferably positioned centrally, leaving no space in the center for the sensor. In such a case, the sensor, along with the opening and the opening structure, can be positioned eccentrically relative to the housing. Similarly, with separate transmitters and receivers, at least one of the transmitters or the other is positioned eccentrically.It is also conceivable that the opening structure comprises an annular aperture instead of a circular aperture. In this case, the opening structure has at least one, preferably two, and particularly preferably at least three annular apertures as structural openings.

[0026] The diffraction pattern of a circular and / or annular aperture is itself circular and exhibits a main lobe along the axis of the detection area, with an intensity maximum on the axis. The axis corresponds to an elevation angle of 0°. As the elevation angle increases, the intensity decreases rapidly until it reaches a first minimum. The intensity distribution of the diffraction pattern of a circular or annular aperture can be calculated and clearly visualized using a first-order Bessel function. For large apertures, e.g., with a radius of 3 λ, the intensity decreases rapidly with increasing elevation angle and shows a first minimum with an intensity of 0 at approximately 12°. This is followed by alternating low maxima and further minima as the elevation angle continues to increase. If the aperture size is reduced, the minima shift to larger elevation angles.Even with a radius of 1 λ, the first diffraction minimum of a circular aperture is located at an elevation angle of approximately 38°. As the radius of the circular aperture approaches λ / 2, the minimum shifts to an elevation angle of 90°. For a single, elongated slit, the minimum is already at a diffraction angle of 90° when the slit width is 1 λ. If the aperture width is further reduced, the minimum remains at 90°, while the relative intensity at the minimum, compared to the intensity at 0°, increases. This means that the width of the main lobe increases as the aperture width decreases.

[0027] To extend the sensor's detection range up to an elevation angle of 90° or even beyond, the opening size of the structural apertures, particularly the radius, diameter, and / or slit width, can be made small compared to the wavelength λ of the emitted waves. If the extension of the detection range is achieved solely through diffraction effects, a minimum sensitivity is maintained at least at an elevation angle of 90°. With only a minimum at 90°, the sensitivity decreases continuously between elevation angles of 0° and 90°. Nevertheless, objects can be detected within an elevation range of at least 0° to 90° and an azimuth range of 0° to 360°. Thus, the detection range corresponds to a complete hemisphere.

[0028] An aperture structure with a single aperture of very small size has the disadvantage that the intensity of the emitted waves decreases as the aperture size decreases, thus reducing the sensor's sensitivity despite an expanded detection range. Therefore, when utilizing diffraction effects, at least two apertures are preferably combined in a single aperture structure, e.g., a circular aperture and one or more annular apertures, or several annular apertures without a circular aperture.

[0029] Measurements with acoustic sensors have shown that, for example, combining a circular aperture with a single concentric ring aperture or annular slit increases the intensity of the maximum at an elevation angle of 0° by approximately 18 dB compared to a single circular aperture. Combining the circular aperture with two concentric ring apertures or annular slits results in an increase of approximately 20 dB compared to a single circular aperture.

[0030] However, the use of multiple structural apertures leads to the formation of one or more secondary minima within the main lobe, the diffraction maximum around the axis of the detection area. The position of these secondary minima can be specifically influenced by carefully selecting the spacing between them. Reducing the distance between two structural apertures shifts the secondary minima up to an elevation angle of 90°. If desired, a specific elevation angle range can even be selectively suppressed by choosing the spacing between two structural apertures such that a secondary minimum falls within the range between 0° and 90° elevation, for example, at 40°.

[0031] To achieve a detection range of up to 90° and potentially beyond, even with multiple structure apertures, and to exhibit no or only very weak sensitivity minima between elevation angles from 0° to 90°, the distances between two structure apertures can be small compared to the wavelength λ. The dimensions of the structure elements, such as the structure apertures, and any distances between them, are considered small compared to the emitted wavelength if they are less than or equal to the wavelength, or if the first and only minimum and / or secondary minimum occurs at a diffraction angle or elevation of 90°. This starts with structure element dimensions on the order of one wavelength, whereby for dimensions ≤ λ, the first and only minimum and / or secondary minimum can already occur at a diffraction angle or elevation of 90°.The dimensions of the structural elements are particularly small compared to the wavelength when they are ≤ λ / 2 and / or ≤ λ / 4 and / or ≤ λ / 8 and / or ≤ λ / 16. Especially in circular aperture structures with several structural elements arranged at least approximately concentrically, it has been shown that it can be advantageous if the aperture width of the structural openings and / or the distances between the structural openings increase from the inside out within the aperture. Similar advantages can also be expected in slightly elliptical or square apertures with structural elements arranged in rows and columns.

[0032] In one embodiment, an opening structure consists of at least one circular aperture and two concentrically arranged annular apertures or annular slits, wherein the radius of the circular aperture is approximately λ / 12, the distance between the circular aperture and the first annular aperture or annular slit is approximately λ / 16, the slit width of the first annular aperture or annular slit is approximately λ / 8, the distance between the first annular aperture and the second annular aperture or annular slit is approximately λ / 8, and the slit width of the second annular aperture or annular slit is approximately λ / 8.

[0033] According to the invention, the openings through which the sensor emits and / or receives the waves are located in a housing side of the fire detector that faces away from the mounting surface and towards the room to be monitored. A sensor can comprise a component capable of both transmitting and receiving, hereinafter referred to as a transducer, or a combination of a transmitter and receiver that share an opening for transmitting and receiving the waves. The sensor can also comprise a separate transmitter and receiver, each with an opening for transmitting and receiving, respectively, or two transducers, one of which acts as a transmitter and the other as a receiver. With two transducers, transmitting and receiving can also occur alternately through both transducers, so that each transducer functions once as a transmitter and once as a receiver. In the case of a spherical or, for example,With a conical fire alarm housing, the sensor is advantageously located at the apex of the detector. With a cylindrical housing, it is positioned on the surface facing the room. To also monitor the area to the sides of the fire alarm, at least two additional sensors can be evenly distributed around the circumference of the fire alarm, particularly on the outer surface, especially with cylindrical housings. These sensors can be equipped with an elongated opening structure to widen their detection range horizontally but not vertically. Thus, with just a few sensors, even with cylindrical housings, the entire area around the fire alarm, both below and to the sides, can be monitored for objects.

[0034] In devices that emit optical waves for object detection, the aperture structures, similar to those in blaze or echelette gratings, can utilize refraction in addition to diffraction effects to expand the detection range. For this purpose, the apertures are made of a transparent material with a different refractive index than the surroundings. Additionally, the material is ground at a specific angle to distribute the intensity of the main lobe at the zeroth diffraction maximum over larger elevation angles.

[0035] As an alternative to widening the field of view through diffraction, a structural opening can also be fitted with a lens or objective. Wide-angle or even fisheye lenses or objectives are suitable for this purpose; these can also be designed in a flat form as Fresnel lenses.

[0036] Utilizing wave refraction offers the advantage of allowing for larger aperture sizes in the structure's openings compared to relying solely on diffraction effects, thus providing greater intensity for object detection. Furthermore, aperture structures that utilize both diffraction and refraction effects can achieve uniform sensitivity across the entire angular range of 0° to 90° elevation.

[0037] The invention also relates to a device for detecting objects, particularly in the vicinity of a fire detector, which can be retrofitted to fire detectors. The device comprises a housing with a mounting surface for at least indirect attachment to or next to a fire detector and a room-facing housing side opposite the mounting surface, and includes a sensor for detecting objects. The sensor emits electromagnetic and / or acoustic waves of a wavelength λ through at least one opening in the room-facing housing side, which is transparent to the waves, into a detection area in the vicinity of the device, particularly in the vicinity of the fire detector. The sensor receives the waves reflected by objects in the detection area through the same or a further opening.The opening and / or the further opening have an opening structure with at least one structural opening as a structural element, which expands the detection range of the sensor in all directions around the axis by means of diffraction effects and / or refraction. The opening structure is designed such that it expands the detection range of the sensor into a complete hemisphere by means of diffraction effects and / or refraction in all directions around the axis, and objects in the hemisphere outside the device are detectable, wherein the structural opening comprises a circular aperture and at least one circumferential slit, in particular an annular slit (13).

[0038] The opening, the further opening and the opening structure of the device have the same structural features as described for the opening, the further opening and the opening structure using the example of the fire alarm.

[0039] The arrangement and dimensions of the structural elements of the aperture structures, as well as the resulting expansion of the detection range, can be determined experimentally, e.g., by numerical simulation, depending on the wavelength used, and verified by measurements on experimental setups. Suitable wavelengths or frequencies for ultrasound are, for example, around 40 kHz, and in the optical range, e.g., between infrared and blue or ultraviolet radiation.

[0040] The fire alarm and the object detection device each include an electronic control and evaluation unit, such as a microcontroller. The control and evaluation unit is configured to activate the sensor to emit waves and to evaluate the received signals. The control and evaluation unit can generate and store an initial distance profile indicating the distance to the nearest object. Warnings can be issued in the event of significant changes to this initial distance profile or when objects are detected within predefined distances.

[0041] The generated distance profile and warnings can be output via a data interface of the device or fire alarm.

[0042] The data interface can be a wired interface, for example, for connection to a detector bus. Alternatively or additionally, it can be a wireless data interface and be based, for example, on a WLAN, Bluetooth, or mobile network standard (GSM, 4G, 5G, or 6G), on NFC, or on acoustic transmission. Distance profiles, as well as other data, can then be viewed by a user on a remote display device, such as a smartphone, tablet, or PC.

[0043] The control and evaluation unit in the fire detector can also perform additional control and evaluation tasks. These include fire detection, alarm notification, energy management, and communication. Alternatively, a separate control and evaluation unit can be provided within the fire detector for fire detector-specific tasks. This control and evaluation unit can be implemented, for example, with a microcontroller, an ASIC, or an ASIC combined with a microcontroller.

[0044] The invention allows for numerous embodiments. Some of these will be briefly explained here with reference to the following figures. Identical elements in the figures are designated with the same reference numerals. Fig. 1a shows a smoke detector with a state-of-the-art sensor for detecting objects. Fig. 1b shows a cross-section through a smoke detector with a scattering point located outside the detector and a state-of-the-art sensor for object detection. Fig. 1c shows a cross-section through a smoke detector with a scattering point located inside the detector and a state-of-the-art sensor for detecting objects. Fig. 2a Figure 1 shows a device according to the invention or a fire detector with a centrally arranged opening for sending and receiving waves. Fig. 2b Figure 1 shows a device according to the invention or a fire detector with two eccentrically arranged openings for sending and / or receiving waves. Fig. 3a bis 3e They show various opening structures with structural elements to widen the detection area in several directions. Fig. 4a shows a section through a cylindrical smoke detector with a scattering point located outside the detector and a sensor for detecting objects with a detection range expanded according to the invention. Fig. 4b shows a section through a spherical smoke detector with a scattering point located inside the detector and a sensor for detecting objects with a detection range expanded according to the invention. Fig. 5a The figure shows a smoke detector in perspective with a central opening with an opening structure and a detection area widened according to the invention. Fig. 5b shows a section through a smoke detector with a central opening with a sensor for detecting objects, an opening structure and a detection area widened according to the invention.

[0045] Fig. 1a Figure 1 shows a perspective view of a state-of-the-art fire detector (1). The fire detector (1) has a housing (4) with smoke inlet openings (9). On a side of the housing of the smoke detector (1) facing the room to be monitored, there is an opening (11) through which waves are sent by a sensor (3) along an axis (6) into a detection area (5) for the purpose of detecting objects. The detection area (5) lies outside the detector (1) in its vicinity and is relatively narrow with an elevation angle α of approximately 25°.

[0046] Fig. 1b Figure 1 shows a cross-sectional view of a prior art cylindrical fire detector (1) with a scattering point (10) located outside the detector. The fire detector (1) has a housing (4). On a housing side of the smoke detector (1) facing the room to be monitored, there is an opening (11) through which waves are sent by a sensor (3) along an axis (6) into a detection area (5) for the purpose of detecting objects. The detection area (5) lies outside the detector (1) in its vicinity and is relatively narrow with an elevation angle α of approximately 30°. The scattering point (10) of the smoke sensor (7) lies within the detection area (5).

[0047] Fig. 1c Figure 1 shows a cross-sectional view of a state-of-the-art fire detector (1) with a spherical housing and a scattered light smoke sensor (7) whose scattering point (10) is located in a measuring chamber (8) in the housing (4) of the detector (1). An opening (11) is located on the housing side of the smoke detector (1) facing the room to be monitored. Waves are emitted through this opening by a sensor (3) along an axis (6) into a detection area (5) for the purpose of detecting objects. The detection area (5) lies outside the detector (1) in its vicinity and is relatively narrow with an elevation angle α of approximately 30°.

[0048] Fig. 2a Figure 1 shows the view of the housing (4) of a fire alarm (1). Approximately in the center of the visible surface on the side of the housing, an opening structure (12) with structural openings (13) can be seen. The opening structure (12) consists of a circular aperture (13) and an annular aperture (13) arranged approximately concentrically to it. Between the circular aperture (13) and the annular aperture (13) is a space (16) shown in black, which is formed from housing material and held in place by three narrow ribs (17) that interrupt the circular ring. As in Fig. 4 As shown in Figures a and 4b, a sensor (3) emits waves into the vicinity of the smoke detector (1) to detect objects. The waves, which encounter objects within a detection range (5), are reflected by them and return to the sensor (3) through the opening structure (12), where they can be detected. The distance to an object can be determined from the travel time between the emission and reception of the waves. If, as required, for example, in DIN SPEC 91388, objects are detected at a distance between 10 cm and 55 cm from the detector (1), a corresponding message can be generated and sent via existing communication channels or at least stored for later retrieval.By dimensioning the structural means of the opening structure (12), namely the structural openings (13) and the distance (16) between them, the detection area (5) of the sensor (3) is widened by diffraction effects in such a way that approximately the entire hemisphere below the detector (1), in the representation above the detector (1), forms the detection area (5).

[0049] Fig. 2b shows, as well as Fig. 2a , the view of the housing (4) of a fire alarm (1). In contrast to Fig. 2a However, two opening structures (12) are shown here, which differ from those in Fig. 2a are positioned eccentrically to the visible surface. Two separate opening structures (12) allow two components to be used as separate transmitters and receivers. Separate transmitters and receivers offer the advantage that signals reflected by the transmitter during transmission can be received by the receiver, and shorter distances can be detected than with a single component used for both transmitting and receiving. Using two components that can both transmit and receive provides additional redundancy in object detection, while a single component used for both transmitting and receiving results in lower component and production costs.With separate transmitters and receivers, a transmission area is formed for each transmitter and a reception area for each receiver, which overlap almost completely due to the respective widening of the transmission area and the reception area by the respective opening structure (12) and form the detection area (5) of the sensor (3) formed from transmitter and receiver in the area of ​​overlap.

[0050] The Figuren 3a bis 3e show different or alternative opening structures (12) to the Fig. 2a , 2b 4a, 4b , 5a und 5b to widen the detection range (5) by means of diffraction. The Fig. 3a und 3b The opening structures (12) with structural openings (13) arranged in rows and columns and separated from each other by gaps forming a grid are shown. With such an opening structure (12), the main lobe of the detection area (5) of the sensor (3) is predominantly widened in four main directions. In the top view, a cross-shaped detection area (5) is obtained with only one sensor (3), as can be achieved in the prior art with four sensors evenly distributed around the circumference of the detector and directed obliquely downwards, and an additional sensor directed directly downwards.

[0051] The Figuren 3c bis 3e The circular opening structures (12) each have a circular aperture (13) as the central opening and several annular apertures (13) as surrounding slots (13), arranged approximately concentrically to the circular aperture (13) at intervals (16). The gaps (16) are formed from the same material as the housing (4) and are held by retaining ribs (17). Thus, the opening structure, in particular the gaps and ribs, is part of the housing. Alternatively, the entire opening structure (12) can also be inserted as a separate element into an opening (11) in the housing (4) of the detector (1). This also applies to the opening structures (12) of the Fig. 3a und 3b In this case, the opening structure is embedded in the housing of the fire detector or device. In both cases, the opening structure is flush with the surface of the room-facing side of the housing.

[0052] In Fig. 3 c The aperture widths and spacings are approximately equal. The diameter of the circular aperture (13) is approximately 1 λ, while the slit widths of the circumferential annular slits (13) and the ring width of the spacings (16) are λ / 2.

[0053] In the Fig. 3 d and 3e In contrast, opening structures (12) with different opening widths and spacings (16) are shown. In the Fig. 3d For example, the radius of the circular aperture (13) is approximately λ / 12, the distance (16) between the circular aperture (13) and the first ring aperture (13) is approximately λ / 16, the slit width of the first ring aperture (13) is approximately λ / 8, the distance (16) between the first ring aperture (13) and the second ring aperture (13) is approximately λ / 8, and the slit width of the second ring aperture (13) is approximately λ / 8.

[0054] In Fig. 13e, the opening widths of the structural openings (13) and the width of the distances (16) between the structural openings (13) increase from the inside to the outside.

[0055] Another opening structure, not shown, has several circular apertures as structural openings, one of which is located in the center of the opening structure and the remaining circular apertures are arranged in one or more concentric circles around it.

[0056] If, in addition to diffraction effects, refraction effects are also to be used to widen the detection range (5), the structural openings (13) are made of a material that has a different refractive index than the surrounding air. This material is also angled so that the wave intensity from the main lobe is refracted away from the axis (6) in the direction of larger elevation angles. The angle itself is selected depending on the refractive index of the material, the wavelength, and the desired direction in which the waves are to be refracted.

[0057] Fig. 4a Figure 1 shows a scattered light smoke detector (1) with an object detection device (2). The cylindrical housing (4) of the detector (1), which is installed in the ceiling (14) and is flush with it, contains a scattered light smoke sensor (7) whose scattering point (10) is located outside the housing (4) in the open air. Also located in the housing (4) is a sensor (3) for object detection, which sends waves through an opening (11) with an opening structure (12) in the housing (4) and receives waves reflected from objects. The waves are sent along an axis (6) into a detection area (5) and are diffracted and / or refracted in all directions away from the axis (6) by the structure and dimensions of the opening structure (12). This results in a hemispherical detection area (5) below the detector (1) and below the ceiling (14).Objects that are located within a distance of 10 cm - 55 cm around or below the detector (1) according to the requirements of DIN SPEC 91388 can thus be reliably detected with a single sensor (3).

[0058] The in Fig. 4b The fire alarm shown (1) is different from Fig. 4a The detector (14) is mounted on the ceiling and has a spherical housing (4) with a measuring chamber (8) containing the scattering point (10) of the scattered light smoke sensor (7). The sensor (3) for detecting objects is located at the apex, the highest or lowest point, of the housing (4). Because the housing (4) is spherical, the transmitted and received waves can be diffracted and / or refracted across the entire azimuth range from 0° to 360° beyond an elevation angle of 90°, allowing areas to the side of the detector to be monitored for objects with just a single sensor (3). This effect is even more pronounced in fire detectors (1) with a conical housing (4) (not shown). In cylindrical fire detector housings (4), as in Fig. 5b At least two additional sensors (not shown) can be attached to the circumference of the detector (1) mounted on the ceiling (14) if the area to the side of the detector is also to be monitored for objects. These sensors can then be provided with modified opening structures that widen the detection area horizontally only. By widening the detection area horizontally, the entire area to the side of the detector (1) can be monitored almost completely for objects with just two laterally oriented sensors. However, whether additional monitoring to the side of the detector is necessary depends on the height of the cylinder of the housing (4) and on whether objects that could disrupt the flow conditions in the vicinity of the detector can already be reliably detected by a sensor (3) with an opening structure (12) according to the invention on the base of the cylinder.An indication of sufficiently good detection is obtained if the test according to DIN SPEC 91388 is passed, according to which boards of the size 1m x 1m must be detected, which are mounted at a distance of up to approx. 50 cm from the detector (1) perpendicular to the ceiling (14).

[0059] Fig. 5a Figure 1 shows a perspective view of a fire detector (1) with a cylindrical housing (4) with smoke inlet openings (9) and an opening structure (12) according to the invention, which is located approximately centrally in a base surface of the housing (4). The opening structure (12) widens the detection area (5) along the axis (6) up to an elevation angle α of 90° or -90°.

[0060] Fig. 5b Figure 1 shows a sectional view of a fire detector (1) with a cylindrical housing (4) mounted on a ceiling (14). Inside the housing (4) are a measuring chamber (8), a circuit board (15), and a sensor (3) for detecting objects. Above the sensor (3), within the housing (4) of the fire detector (1), is an opening structure (12) that expands the detection range (5) of the sensor (3) through diffraction and / or refraction. The opening structure (12) is located in the base of the housing (4) facing the monitored area. However, it can also be subsequently inserted into an existing opening (11). This can be done regularly during production or retrofitted to existing object detection devices (2) to expand the detection range (5). In this case, recalibration of the sensor (3) is advisable.

[0061] Although in none of the Fig. 2 a, 2b, 4a, 4b 5a und 5b As shown, the fire alarm (1) or the device for detecting objects (2) comprises at least a control and evaluation circuit, means for displaying alarms and for detecting objects, means for communication and at least one power supply. Bezugszeichenliste

[0062] 1 Fire detectors, scattered light smoke detectors 2 Device for detecting objects 3 sensor 4 Housing 5 Detection area 6 axis 7 smoke detector 8 Measuring chamber 9 Smoke ingress openings 10 Scatter point 11 opening 12 Opening structure 13 Structural aperture, circular aperture, ring aperture 14 Ceiling 15 Circuit board 16 Distance 17 Boarding platforms

Claims

1. Fire detector (1) comprising a device for detecting objects in the surroundings of the fire detector (1), wherein the fire detector comprises a housing (4) having a fastening surface for at least indirect attachment to an installation surface (14), and a housing side opposite the fastening surface and facing the room, and wherein the device comprises at least one sensor (3) for detecting objects, which emits electromagnetic and / or acoustic waves of wavelength λ through at least one opening (11), which is transmissive to the waves, in the housing side facing the room of the housing (4), along an axis (6) into a detection region (5) in the surroundings of the fire detector (1), and receives the waves reflected by objects in the detection region (5) through the same opening or through a further opening (11), characterised in that the opening (11) and / or the further opening (11) comprises an aperture structure (12) having at least one structural aperture (13) as a structural element, wherein the aperture structure (12) widens the detection region (5) of the sensor (3) around the axis (6) by means of diffraction effects or diffraction and refraction effects.

2. Fire detector according to claim 1, characterised in that the aperture structure (12) lies in the housing side facing the room.

3. Fire detector according to any one or more of the preceding claims, characterised in that the structural aperture (13) comprises a circular aperture (13) and / or a circumferential slit, in particular an annular slit (13).

4. Fire detector according to any one or more of the preceding claims, characterised in that the structural aperture (13) has an aperture width, in particular a radius, a diameter and / or a slit width, which is small compared with the wavelength λ of the emitted waves.

5. Fire detector according to any one or more of the preceding claims, characterised in that spacings (16) between two structural apertures (13) are small compared with the wavelength λ.

6. Fire detector according to claim 4 and / or claim 5, characterised in that small compared with the wavelength means ≤ 1 λ, in particular ≤ λ / 2 and / or ≤ λ / 4 and / or ≤ λ / 8 and / or ≤ λ / 16.

7. Fire detector according to any one or more of the preceding claims, characterised in that the aperture widths of the structural apertures (13) and / or the spacings (16) between the structural apertures (13) become larger from the inside to the outside within the opening (11).

8. Fire detector according to any one or more of the preceding claims, characterised in that the aperture structure (12) consists of at least one circular aperture (13) and two annular apertures arranged concentrically thereto, wherein the radius of the circular aperture (13) is approximately λ / 12, the spacing (16) between the circular aperture (13) and the first annular aperture (13) is approximately λ / 16, the slit width of the first annular aperture (13) is approximately λ / 8, the spacing (16) between the first annular aperture (13) and the second annular aperture (13) is approximately λ / 8, and the slit width of the second annular aperture (13) is approximately λ / 8.

9. Device for detecting objects in the surroundings of a fire detector (1), wherein the device comprises a housing (4) having a fastening surface for at least indirect attachment to or beside a fire detector (1), and a housing side opposite the fastening surface and facing the room, and wherein the device comprises a sensor (3), which emits electromagnetic and / or acoustic waves through at least one opening (11), which is transmissive to the waves, in the housing side facing the room of the housing (4), along an axis (6) into a detection region (5) in the surroundings of the device, and receives the waves reflected by objects in the detection region (5) through the same opening or through a further opening (11), characterised in that the opening (11) and / or the further opening (11) comprises an aperture structure (12) having at least one structural aperture (13) as a structural element, which widens the detection region (5) of the sensor (3) around the axis (6) by means of diffraction effects or diffraction and refraction effects, wherein objects outside, in particular below, the device are detectable.

10. Device according to claim 9, characterised in that the aperture structure (12) lies in the housing side facing the room.

11. Device according to claim 9 and / or claim 10, characterised in that the structural aperture (13) comprises a circular aperture (13) and / or at least one circumferential slit, in particular an annular slit (13), or at least two circumferential slits.

12. Device according to any one or more of claims 9 to 11, characterised in that the structural aperture (13) has an aperture width, in particular a radius, a diameter and / or a slit width, and spacings (16) between the structural apertures (13), which are small compared with the wavelength λ of the emitted waves.

13. Device according to claim 12, characterised in that small compared with the wavelength means ≤ 1 λ, in particular ≤ λ / 2 and / or ≤ λ / 4 and / or ≤ λ / 8 and / or ≤ λ / 16.

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