Smoke detector

Abstract

A smoke detector (2) according to the invention comprises a transmitter (4) for emitting electromagnetic radiation through an exit opening (28) and a receiver (8) for receiving electromagnetic radiation through an entry opening (30), wherein the transmitter (4) and the receiver (8) are arranged inside the smoke detector (2) and are designed and oriented such that they define a measuring range (22) outside the smoke detector (2). A light barrier (34) is arranged at least on the surface (12) of the smoke detector between the transmitter (4) and the receiver (8).

Description

[0001] The present invention relates to a smoke detector, in particular an optical smoke detector, for detecting smoke particles in the air.

[0002] Optical smoke detectors typically consist of a transmitter that emits electromagnetic radiation and a receiver that receives electromagnetic radiation. The transmitter and receiver are aligned in such a way that the electromagnetic radiation emitted by the transmitter does not directly reach the receiver, but only upon reflection, for example, from aerosol particles in smoke (smoke particles).

[0003] In conventional smoke detectors, this process takes place in a detection chamber inside the smoke detector, which is separated from the surroundings by a light labyrinth, so that essentially no ambient light and no other interfering influences can penetrate the detection chamber, but gases can.

[0004] In another design, smoke detectors do not have a detection chamber and are therefore also called (detection-)chamberless smoke detectors. The transmitter and receiver of such smoke detectors are directed outwards and define a virtual detection chamber or measuring area in the space below the smoke detector. Since the space below the smoke detector is unprotected, smoke detectors of this design are more susceptible to certain interferences, such as reflections of the emitted electromagnetic radiation caused by foreign objects.

[0005] It is an object of the present invention to provide a smoke detector, in particular an optical smoke detector, which has high reliability and low susceptibility to interference.

[0006] This problem is solved by the subject matter of claim 1. Preferred embodiments are the subject matter of the dependent claims.

[0007] A smoke detector according to the invention for detecting smoke particles in air comprises a smoke detector surface with an outlet opening and an inlet opening, as well as a transmitter for emitting electromagnetic radiation through the outlet opening and a receiver for receiving electromagnetic radiation through the inlet opening. The transmitter and the receiver are arranged inside the smoke detector and are designed and oriented such that they define a measuring range outside the smoke detector. The smoke detector further comprises a light barrier, which is arranged at least on the smoke detector surface between the transmitter and the receiver.

[0008] In this way, a smoke detector is provided in which reflection of near-surface radiation onto the receiver is largely avoided, thus reducing the smoke detector's susceptibility to interference. While the radiation emitted by the transmitter is preferably directed towards the measuring area, it breaks through the exit opening of the smoke detector and scatters into near-surface areas of the smoke detector's surface. It has been found that near-surface radiation, in particular, leads to increased interference, especially false alarms of smoke detectors, for example, through reflection from particles that tend to accumulate near the ceiling of a room or from insects that land on the smoke detector. The light barrier prevents such reflections from reaching the receiver. Since the measuring area is positioned at a certain distance from the smoke detector's surface, it remains...The radiation directed at the detector remains essentially unaffected by the light barrier, ensuring reliable activation of the smoke detector in the event of a fire. Such a light barrier can be simple in design and installation. No complex electronic solution or signal processing is required. Rather, the smoke detector can remain essentially unchanged, requiring only a few simple adjustments.

[0009] The smoke detector is preferably an optical or photoelectric smoke detector. Accordingly, the transmitter preferably comprises a light-emitting diode, in particular an infrared light-emitting diode or a laser diode. The emitted electromagnetic radiation is preferably quantum or photon radiation, in particular light, regardless of frequency or wavelength. Particularly preferred is infrared light, which can be emitted in a directed manner. However, it can also be, for example, microwaves, lasers, or ultraviolet radiation. The receiver can comprise a light-sensitive sensor, in particular a photodiode.

[0010] The smoke detector is preferably a chamberless smoke detector. It then has neither a detection chamber nor a light labyrinth. Instead, the design and orientation of the transmitter and receiver define a measuring area outside the smoke detector and at a distance from the smoke detector surface.

[0011] In principle, the sensor's radiation pattern can be essentially conical, depending in particular on the light source used and any scattering at the point of exit from the smoke detector, for example, due to a translucent cover over the exit opening. The receiver's detection area, from which electromagnetic radiation reaches the receiver, can also be essentially conical. The measuring range is preferably defined where the sensor's radiation pattern and the receiver's detection area overlap. Smoke particles are detected particularly reliably in this area.

[0012] The smoke detector surface is preferably an outer surface of the smoke detector. When installed, the smoke detector surface can face the room. If desired, the smoke detector surface can be essentially flush with or positioned a short distance from the room ceiling. In a chamberless smoke detector, the smoke detector surface is preferably the only visible surface of the smoke detector. Since no gas inlet to the smoke detector is required, the rest of the smoke detector, unlike conventional smoke detectors with a detection chamber, can be located in the ceiling or behind a ceiling panel. The smoke detector surface can generally be essentially flat. Furthermore, the smoke detector surface can have additional openings, for example, for further detection or indicator devices, such as a status LED.

[0013] The light barrier is preferably designed and configured to shield the receiver from electromagnetic radiation, in particular from electromagnetic radiation that is not reflected from the measuring area onto the receiver, such as near-surface radiation.

[0014] The light barrier is preferably opaque. This reliably prevents light from passing through the light barrier and shields the receiver accordingly.

[0015] The light barrier can be made of a metal, particularly stainless steel, aluminum, or an aluminum alloy. This ensures the barrier's opacity and makes it especially resistant to external influences and tampering. Alternatively, the light barrier can also be made of plastic.

[0016] The housing of the smoke detector, in particular a component of the housing encompassing the smoke detector surface, such as a cover or lid, is preferably made of a metal, especially stainless steel, aluminum, or an aluminum alloy. This makes the housing particularly stable and durable. Alternatively, other components of the housing, as well as the component encompassing the smoke detector surface, can be made of plastic.

[0017] In a preferred embodiment of the smoke detector, the light barrier is rib-shaped and has a first section that extends substantially perpendicular to the smoke detector surface. This reliably shields near-surface radiation. The first section of the light barrier preferably extends away from the smoke detector surface. The light barrier, and in particular its first section, preferably lies flush with the smoke detector surface. This prevents light from passing between the light barrier and the smoke detector surface.

[0018] In order to reliably shield near-surface radiation while minimizing or completely eliminating any influence on the measuring range, the light barrier, and in particular its first section, preferably has a height relative to the smoke detector surface of between 2 mm and 10 mm, more preferably between 3 mm and 8 mm, and even more preferably between 4 mm and 6 mm.

[0019] To prevent near-surface radiation from being reflected laterally around the light barrier onto the receiver, the light barrier preferably has a width of between 10 mm and 40 mm, preferably between 20 mm and 30 mm.

[0020] By minimizing the thickness of the light barrier, its optical appearance and its influence on the measuring range can be further reduced. Therefore, the light barrier preferably has a thickness between 0.5 mm and 5 mm, more preferably between 1 mm and 2 mm.

[0021] The dimensions specified herein allow the design and orientation of the sensors in existing chamberless smoke detectors to remain essentially unchanged, requiring only an adjustment to the smoke detector surface for contact with the light barrier. However, it is understood that other dimensions are also possible.

[0022] In a preferred embodiment, a first receiving opening is formed in the smoke detector surface, into which the light barrier is inserted. For example, the first receiving opening is slot-shaped. The light barrier can then be inserted into the slot-shaped first receiving opening. In this way, a stable connection between the light barrier and the smoke detector surface is created.

[0023] It is further preferred if the light barrier has a second section extending from the first section and inserted into the first receiving opening. This second section can then extend through the first receiving opening in the smoke detector surface, optionally into an electronics compartment of the smoke detector behind the smoke detector surface. The second section of the light barrier can be integral with the first section, preferably as an extension of the first section. The first and second sections of the light barrier can have an identical and constant cross-section.

[0024] The light barrier can further comprise at least one cylindrical connecting element extending from a shoulder-shaped shoulder of the light barrier and inserted into a second receiving opening in the smoke detector surface. Preferably, the light barrier has two shoulder-shaped shoulders, each extending from which a cylindrical connecting element is inserted into a second receiving opening. The at least one shoulder-shaped shoulder can extend from the first section of the light barrier in a width direction. The light barrier is particularly preferably symmetrical. In this way, a secure, for example, positive-locking and / or force-locking, as well as rotationally fixed connection between the light barrier and the smoke detector surface can be created.

[0025] The outlet and inlet openings are preferably each fitted with a translucent cover. This prevents the ingress of foreign matter and contamination of the transmitter and receiver. The near-surface radiation generated by the refraction of electromagnetic radiation at the translucent cover can be shielded by the light barrier.

[0026] In a preferred embodiment, the outlet opening and the inlet opening are formed jointly by a single elongated opening in the smoke detector surface. This has the advantage that additional sensors can be arranged between the transmitter and the receiver, which can detect further parameters, such as the degree of contamination, through this opening. The elongated opening preferably extends longitudinally from a region of the transmitter to a region of the receiver.

[0027] Preferably, the light barrier divides this elongated opening into an exit opening on one side and an entry opening on the other. It is advantageous if the light barrier extends so far into the smoke detector that no radiation can reach the receiver from the transmitter through the elongated opening and any cavity behind it.

[0028] In general, the light barrier is positioned between the transmitter and the receiver, i.e., between an area where the emitted radiation exits the smoke detector surface and an area where received or detected radiation enters the smoke detector surface. The light barrier is located at least on the smoke detector surface and projects from it. Preferably, the light barrier also extends into the smoke detector to prevent radiation from reaching the receiver even inside the detector. The position of the light barrier between the transmitter and the receiver is, in principle, freely selectable. However, it is preferably positioned closer to the receiver than to the transmitter. In this way, the receiver is reliably shielded, while additional sensors that also emit radiation can be provided on the transmitter side.

[0029] The vertical direction of the light barrier can generally be defined perpendicular to the smoke detector surface. The horizontal direction of the light barrier is defined perpendicular to the vertical direction, and the thickness direction of the light barrier is defined perpendicular to both the vertical and horizontal directions. The light barrier preferably extends substantially across a plane defined by the vertical and horizontal directions. Therefore, its thickness is preferably significantly less than its width and height. If a center line is defined between the transmitter and receiver in a top view of the smoke detector surface, this line preferably runs perpendicular to the horizontal direction and parallel to the thickness direction of the light barrier.

[0030] Further features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings. Fig. Figure 1 is a schematic cross-sectional view of a smoke detector according to the invention. Fig. Figure 2 is a perspective view of the top of a smoke detector according to the invention. Fig. Figure 3 is a perspective view of a light barrier of a smoke detector according to the invention.

[0031] In Fig. Figure 1 shows a smoke detector 2 according to the invention schematically in a cross-sectional view to explain its functions and essential components.

[0032] The smoke detector 2 is an optical smoke detector. The smoke detector 2 comprises a transmitter 4 for emitting electromagnetic radiation, indicated by an essentially conical radiation area 6, and a receiver 8 for receiving electromagnetic radiation, indicated by an essentially conical detection area 10.

[0033] In the illustrated embodiment, the smoke detector 2 is designed as a chamberless smoke detector. In this case, a smoke detector surface 12 can be arranged essentially flush with or in close proximity to the ceiling 14, while the rest of the smoke detector 2 is housed in the ceiling 14 or behind a ceiling panel. A housing 16 of the smoke detector 2 is indicated by dashed lines and can define an electronics compartment 18 within it, in which electrical components of the smoke detector 2 are housed. Furthermore, the smoke detector 2 can include a cover or lid 20, which here forms the smoke detector surface 12 and closes the housing 16. Other configurations are conceivable.

[0034] In smoke detector 2, the transmitter 4 and the receiver 8 are arranged inside the smoke detector 2 and are designed and oriented such that they define a measuring range 22 below the smoke detector 2. The measuring range 22 is defined in particular by the fact that the radiation range 6 and the detection range 10 overlap there. In the measuring range 22, smoke particles can therefore be detected particularly well and reliably because the radiation emitted by the transmitter 4 is reflected at least partially by them in the direction of the receiver 8.

[0035] The transmitter 4 preferably emits pulsed, directed light at a defined angle, as illustrated by the radiation area 6. In the event of a fire, the light is scattered by smoke particles in the measuring area 22 and strikes the receiver 8, which is, for example, a photodiode. The receiver 8 generates a receiver signal, which is evaluated, for example, by an evaluation unit 24 connected to the receiver 8 and triggers an alarm when a preset response threshold is exceeded.

[0036] In addition to the evaluation unit 24, a control unit 26 and, if necessary, a power supply can be provided in the electronics compartment 18 of the smoke detector. It would also be conceivable to wire the smoke detector 2 to an external power supply and / or a fire alarm system. A corresponding connection 27 is indicated by a dashed line.

[0037] The radiation emitted by the transmitter 4 exits the smoke detector 2 through an exit opening 28 in the smoke detector surface 12, and the radiation received by the receiver 8 enters the smoke detector 2 through an entry opening 30 in the smoke detector surface 12. The exit opening 28 and the entry opening 30 are preferably provided with a translucent cover 32, 33, which protects the transmitter 4 and receiver 8. Due to the refraction of the emitted radiation at the cover 32, near-surface radiation in the area of ​​the smoke detector surface 12 can be reflected onto the receiver 8, for example, by insects landing on the smoke detector 2.

[0038] The smoke detector 2 according to the invention therefore comprises a light barrier 34, which is arranged between the transmitter 4 and the receiver 8 and shields the receiver 8 from radiation, in particular near-surface radiation, which could be undesirably reflected onto the receiver 8. The light barrier 34 is arranged at least on the smoke detector surface 12 and projects from it, but preferably also extends through the smoke detector surface 12 into the smoke detector 2. As in Fig. As can be seen in 1, near-surface radiation outside the measuring range 22 can be effectively shielded by the light barrier 34, while the measuring range 22 and thus the regular function of the smoke detector 2 remains essentially unaffected.

[0039] Based on Fig. 2 and Fig. Figure 3 describes details of the smoke detector surface 12 of a smoke detector 2 according to the invention and of the light barrier 34 of a smoke detector 2 according to the invention. The smoke detector 2 can be configured according to Fig. 1 corresponds, but is not limited to this embodiment.

[0040] In the Fig. In the embodiment shown in Figure 2, the outlet opening 28 and the inlet opening 30 in the smoke detector surface 12 are jointly formed by a single elongated opening 36. However, these can also be separate openings. The elongated opening 36 extends from a region of the transmitter 4 (in the case of outlet opening 28) to a region of the receiver 8 (in the case of inlet opening 30). Connecting the transmitter 4 and the receiver 8 in a top view defines a center line M. A longitudinal or principal direction of extension of the elongated opening 36 runs parallel to the center line M.

[0041] Furthermore, the smoke detector surface has a first receiving opening 38 into which the light barrier 34 can be inserted. The first receiving opening 38 is preferably slot-shaped and is divided here into two sections 38a, 38b by the elongated opening 36. A main direction of extension of the first receiving opening 38 preferably runs perpendicular to the center line M in a plane parallel to the smoke detector surface 12.

[0042] In the preferred embodiment shown, the light barrier 34 is essentially rib-shaped and has a first section 40 and a second section 42. The first section 40 extends essentially perpendicular to the smoke detector surface 12 and projects from it. The second section 42 extends from the first section 40 and is inserted into the first receiving opening 38. This allows the light barrier 34 to be easily connected to the smoke detector 2, specifically to its cover 20, and reliably shields the receiver 8 both inside and outside the smoke detector 2. In this case, the elongated opening 36 is divided by the light barrier 34 into the outlet opening 28 and the inlet opening 30.

[0043] The first section 40 and the second section 42 of the light barrier 34 are preferably integrally formed and have a uniform cross-section. The light barrier 34 may also have two shoulder-shaped projections 44a, 44b extending from the first section 40 of the light barrier 34 in a lateral direction B of the light barrier 34. The lateral direction B preferably runs perpendicular to the center line M in a plane parallel to the smoke detector surface 12. The two shoulder-shaped projections 44a, 44b each have a bearing surface 48a, 48b with which the light barrier 34 can rest on the smoke detector surface 12.

[0044] From each of the two shoulder-shaped sections 44a, 44b, a cylindrical connecting element 50a, 50b extends, each of which is inserted into a second receiving opening 52a, 52b in the smoke detector surface 12. The light barrier 34 therefore preferably has a symmetrical structure. By receiving the second section 42 in the first receiving opening 38 and the connecting elements 50 in the second receiving openings 52a, 52b, a positive-locking and / or force-locking and rotationally fixed connection can be established between the light barrier 34 and the cover 20.

[0045] In Fig.Figure 3 further specifies a height direction H and a thickness direction D, which are oriented perpendicular to each other and perpendicular to the width direction B. The height direction H preferably runs perpendicular to the center line M or to the smoke detector surface 12, and the thickness direction D preferably runs parallel to the center line M. Overall, the light barrier 34 has a substantially planar shape, with its width and height being significantly greater than its thickness.

[0046] The light barrier 34 described herein effectively shields the receiver 8 from reflections of near-surface radiation, thereby making the smoke detector 2 less susceptible to interference. The details of the smoke detector 2 with light barrier 34 described herein serve only to illustrate preferred embodiments. Variations within the scope of protection defined by the claims are obvious to those skilled in the art.

Claims

[1] Smoke detector (2), in particular optical smoke detector (2), for detecting smoke particles in the air comprising: a smoke detector surface (12) with an exit opening (28) and an entry opening (30), and a transmitter (4) for emitting electromagnetic radiation through the exit opening (28) and a receiver (8) for receiving electromagnetic radiation through the entry opening (30), wherein the transmitter (4) and the receiver (8) are arranged inside the smoke detector (2) and are designed and oriented such that they define a measuring area (22) outside the smoke detector (2), characterized by , that the smoke detector (2) includes a light barrier (34) which is arranged at least on the smoke detector surface (12) between the transmitter (4) and the receiver (8). [2] Smoke detector (2) according to claim 1, characterized by , that the light barrier (34) is opaque. [3] Smoke detector (2) according to claim 1 or 2, characterized by , that the light barrier (34) is made of a metal, in particular of aluminium or an aluminium alloy. [4] Smoke detector (2) according to any of the preceding claims, characterized by , that the light barrier (34) is rib-shaped and has a first section (40) which extends essentially perpendicular to the smoke detector surface (12). [5] Smoke detector (2) according to claim 4, characterized by , that the first section from the smoke detector surface (12) has a height of between 2 mm and 10 mm, preferably between 3 mm and 8 mm, more preferably between 4 mm and 6 mm. [6] Smoke detector (2) according to any of the preceding claims, characterized by , that a first receiving opening (38) is formed in the smoke detector surface (12), into which the light barrier (34) is inserted. [7] Smoke detector (2) according to claim 4 and 6, characterized by, that the light barrier (34) has a second section (42) extending from the first section (40) and inserted into the first receiving aperture (38). [8] Smoke detector (2) according to any of the preceding claims, characterized by , that the light barrier (34) has at least one cylindrical connecting element (50a, 50b) extending from a shoulder-shaped shoulder (44a, 44b) of the light barrier (34) and inserted into a second receiving opening (52a, 52b) in the smoke detector surface (12). [9] Smoke detector (2) according to any of the preceding claims, characterized by , that the outlet opening (28) and the inlet opening (30) are provided with a translucent cover (32, 33). [10] Smoke detector (2) according to any of the preceding claims, characterized by, that the exit opening (28) and the entry opening (30) are formed by an elongated opening (36) in the smoke detector surface (12) and the light barrier (34) divides this elongated opening (36) into the exit opening (28) and the entry opening (30).

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