SMOKE DETECTOR

Description

Domaine technique

[0001] This description relates generally to smoke detection devices. Technique antérieure

[0002] There are many smoke detectors available to prevent fires in homes, businesses and industries.

[0003] Document JP 2008 077473 describes a smoke detector according to the preamble of claim 1.

[0004] US 3,460,124 describes a smoke detector.

[0005] Document CN 105 448 028 describes a light detection type smoke detector based on plastic optical fiber transmission.

[0006] Document DE 10 2016 121369 describes a smoke measuring cell for use in a photoelectric smoke detector. Summary of the invention

[0007] There is a need to improve current smoke detectors, particularly to make them more reliable and extend their lifespan.

[0008] The invention is as defined in claims 1 to 16. Brève description des dessins

[0009] These and other features and advantages will be set forth in detail in the following description of particular embodiments given without limitation in relation to the attached figures, among which: there figure 1 is a perspective, partial and schematic representation of an embodiment of a smoke detector; the figure 2 is a perspective representation of an embodiment of an element of the detector of the figure 1 ; there figure 3 is a representation by partial and schematic views (A), (B) and (C), respectively lateral, from above and in perspective, of an embodiment of a mobile assembly of the detector of the figure 1 ; there figure 4 is a perspective representation and by views (A), (B) and (C), partial and schematic, of an embodiment of parts of the detector of the figure 1 ; there figure 5 is a partial, schematic side view of an embodiment of the smoke detector of the figure 1 ; and the figure 6 is a representation, by views (A) and (B), partial and schematic, respectively in perspective and in section of another embodiment of a smoke detector; the figure 7 is a representation, by partial and schematic perspective views (A) and (B), of another embodiment of a smoke detector, not covered by the invention. Description des modes de réalisation

[0010] The same elements have been designated by the same references in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same references and may have identical structural, dimensional and material properties.

[0011] For the sake of clarity, only the steps and elements useful for understanding the embodiments described have been shown and are detailed. In particular, the electronic control and measurement circuits as well as the light-emitting diodes and optical detectors have not been detailed, the embodiments described being compatible with the structures and operation of conventional electronic circuits, diodes and detectors.

[0012] Unless otherwise specified, when two elements are referred to connected together, this means directly connected without intermediate elements other than conductors, and when two elements are referred to connected or coupled together, this means that these two elements can be connected or be connected or coupled through one or more other elements.

[0013] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "upper", "lower", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made unless otherwise specified to the orientation of the figures.

[0014] Unless otherwise specified, the expressions "about", "approximately", "substantially", and "of the order of" mean to within 10%, preferably to within 5%.

[0015] Various examples of implementation and embodiment are set forth below. Regardless of the designation given to these examples (embodiments, examples, variants, etc.) and the qualifiers used (e.g., preferably, etc.), only the parts of the description included within the scope of the claims are part of the present invention, the other examples being set forth only for illustrative purposes and being useful only to highlight specific aspects of the invention in relation to what is not part of it.

[0016] The embodiments described below apply to smoke detection, particularly for detecting fires. Some smoke detectors also include heat or carbon monoxide detection functions.

[0017] The installation of smoke detectors is becoming increasingly mandatory. Their operation, characteristics, and installation criteria are generally governed by standards.

[0018] The installation and operation of detectors are periodically checked, particularly in businesses and industrial environments. In particular, the CE EN 14604 standard sets out detection conditions.

[0019] There are two main categories of smoke detectors: ion detectors and optical detectors.

[0020] The embodiments described, by way of example, relate to optical detectors. These embodiments apply, however, more generally to any system for self-cleaning and detecting residual obstructions in a detector.

[0021] An optical smoke detector contains an optical chamber, a light-emitting diode (LED), and a receiver (photoelectric cell). The LED emits a light signal that, normally (in the absence of smoke), is absorbed by the walls of the chamber without reaching the detector. In the presence of smoke, particles suspended in the smoke reflect the light. The light beam is thus dispersed in the chamber and comes into contact with the receiver or photodetector. If the light signal received by the receiver is higher than a set threshold, an alarm is triggered.

[0022] The optical chamber is generally designed to: be black and opaque to outside light; be able to be crossed by ambient air and therefore have walls that let air pass through; and have walls that do not let insects or dust pass through.

[0023] To meet all these criteria, some current detectors have walls defining indirect passages from the outside to the inside of the chamber. These walls are positioned in a circle. The LED and the photodetector are placed in the chamber.

[0024] The sizing of the passages determines the reliability of the detector and results from a compromise between the need to isolate the chamber from the outside and to allow air to pass through it.

[0025] Furthermore, periodic functional tests are usually necessary.

[0026] The described embodiments originate from a new analysis of the operation over time of a detector.

[0027] One could consider, to make the detectors more reliable, increasing the size of the passages between the room and the outside. This would allow air to pass through but would also allow some insects and dust to pass through. Conversely, one could consider reducing the size of the passages to limit the passage of external dust that triggers false alarms. However, this would encourage the passages to become clogged and would then require either frequent manual cleaning or result in a lack of detection.

[0028] There figure 1 is a perspective, partial and schematic representation of an embodiment of a smoke detector 1.

[0029] Detector 1 shown in figure 1 comprises several parts including an optical chamber opaque to external light, delimited at the periphery by a stack of elements 17 each comprising a ring 171.

[0030] The rings 171 are concentric. Each ring 171 has, in cross-section, an open shape in an axial direction of the stack. More specifically, the cross-section of the rings 171 may have the general shape of a "V" or a "U".

[0031] The rings 171 are stacked and nested within each other, so as to delimit interstices or spaces between rings 171 where air can circulate freely between the chamber and the outside. By their section, the rings 171 create air circulation baffles. All of the baffles form a baffle system.

[0032] As an alternative embodiment, the rings 171 may, during their manufacture, be molded in one go to form a single piece.

[0033] In the embodiment of the figure 1 , the detector 1 comprises a vertical stack containing three elements 17, therefore three rings 171. The number of elements 17, therefore rings 171, can be between 1 and 20, preferably between 1 and 6 and is preferably equal to 3.

[0034] In the embodiment as shown in figure 1 , the detector 1 further comprises: a mobile assembly 11 capable of rotating freely around an axis Z, corresponding to the axis of the stack of elements 17; a housing 19 having an upper face 15 on which the stack of elements 17 rests; and a cover 13 which closes the chamber opposite the housing 19.

[0035] The cover 13 and the upper face 15 of the housing 19 close the chamber at its two axial ends. Electronic components of the optical chamber, such as for example an LED and a photodetector (not shown in the figure 1 ), are fixed to the face 15 or to the cover 13.

[0036] The mobile assembly 11 has several functions which will be described later in more detail in relation to the figure 3 .

[0037] On the one hand, it can eliminate obstacles (dust, insects, etc.) to air circulation, or detect obstructions that it cannot clean.

[0038] On the other hand, it can ventilate the interior of the room.

[0039] In addition, it can detect obstacles in the environment close to detector 1.

[0040] The housing 19 also contains all the electronic circuits necessary for the operation of the detector 1. The LED and the photodetector are notably connected to these circuits.

[0041] There figure 2 is a perspective representation of an embodiment of an element 17 of the detector 1 of the figure 1 .

[0042] Each element 17 is composed of a ring 171 and assembly pads 172. The assembly pads 172 are integral with the ring 171. In the example of the figure 2 , the pads 172 are inside the rings 171.

[0043] In the embodiment of the figure 2 , the element 17 comprises four assembly pads 172. In practice and according to the embodiment, the number of assembly pads 172 per element 17 can be between 1 and 10, preferably between 2 and 5 and is preferably equal to 4.

[0044] The assembly pads 172 make it possible to assemble the elements 17, the cover 13 and the housing 19 together. The assembly pads 172 consolidate the detector 1 and impose, by their height h 1 , a distance between the rings 171. The pads 172 of an element 17 rest on the pads 172 of the element 17 located just below or, for the first ring 171 of the stack, on the face 15 of the housing 19. The pads 172 of the last element 17 receive the cover 13.

[0045] The larger (higher) the pads 172, the larger (wider) the gap between the rings 171 in the stack. Conversely, the smaller the pads 172, the smaller (narrower) the gap between the rings 171.

[0046] In the embodiment of the figure 2 , the elements 17 of a stack all have identical assembly pads 172. Thus, all the rings 171 are spaced from each other by the same distance, and this throughout the stack.

[0047] In another embodiment not shown, it is possible to envisage imposing different distances between the rings 171 of the stack. Thus, the size of the gaps between the rings 171 could vary with the distance of the ring 171 from the housing 19.

[0048] The rings 171 are not flat. Thus the two branches (inner and outer) of the ring 171 form an angle (not shown in the figure 2 ). We call α the angle formed between the two branches of the ring 171. The angle α corresponds either to the angle of the triangle for a ring 171 in "V" (straight branches), or to the angle of the triangle in which a ring 171 in "U" is inscribed (rounded branches).

[0049] The angle α is generally the same for all the rings 171 of the same stack. However, it may alternatively be different depending on the embodiment.

[0050] The angle α is for example between 10 and 170°, preferably between 45 and 120°, the angle α being preferably equal to approximately 90°, for example equal to 90°.

[0051] Each ring 171 has a height h 2 . The height h 2 corresponds to the height between the lowest point of the section of the ring 171 and the highest point (the top of the point or rounding).

[0052] The height h 2 of a ring 171 is for example between 0.1 and 3 cm, preferably between 0.5 and 1.5 cm, the height h 2 being preferably equal to approximately 0.7 cm, for example equal to 0.7 cm.

[0053] The height h 1 of an assembly pad 172 is for example between 0.1 and 3 cm, preferably between 0.5 and 1.5 cm, the height h 1 being preferably equal to approximately 0.6 cm, for example equal to 0.6 cm.

[0054] The height h 1 is preferably less than the height h 2 so that the baffles prevent direct external light.

[0055] Each ring 171 has a width w 1 for example between 0.1 and 3 cm, preferably between 0.7 and 2 cm, the width w 1 being preferably equal to approximately 1.5 cm, for example equal to 1.5 cm.

[0056] The number of elements 17 and the spacing of the rings 171 are determined according to the environment in which the detector 1 is located (dust, insects, brightness, etc.). These two parameters are adjusted so that the ambient air can sufficiently ventilate the chamber, that outside light cannot enter the chamber and that dust and insects are blocked by the baffles.

[0057] There figure 3 is a representation by views (A), (B) and (C), partial and schematic, respectively lateral, from above and in perspective, of an embodiment of a mobile assembly 11 of the detector 1 of the figure 1 .

[0058] The mobile assembly 11 is, in the embodiment of the figure 3 , external to the stack of elements 17. Thus, the mobile assembly 11 rotates around the stack of elements 17 along the Z axis.

[0059] The movable assembly 11 is preferably driven by a motor (placed in the housing 19), which allows its rotation to be generated automatically. Alternatively, the movable assembly 11 can be rotated manually.

[0060] In the embodiment of the figure 3 , the mobile assembly 11 comprises two arms 112 aligned, on either side of the axis of rotation. The term "arm" 112 refers to a part of the mobile assembly 11 which is connected to the axis Z of rotation and which extends in a direction orthogonal to this same axis Z.

[0061] The number of arms 112 may be between 1 and 20, preferably between 1 and 6, the number of arms being preferably equal to 2.

[0062] Preferably, each arm 112 carries a module comprising legs 113, or a fin 111. Thus, a detector 1 with several arms 112 can receive one or more leg modules 113 and / or one or more fins 111.

[0063] In the embodiment of the figure 3 , a first arm 112 of the mobile assembly 11 receives a module of three legs 113. In practice, the number of legs 113 is generally equal to the number of elements 17 that the detector 1 comprises.

[0064] The legs 113 are, in the detector 1, interposed between two successive rings 171. Thus, the legs 113 rotate in the gaps between the rings 171. In addition, a leg 113 rotates in the gap created between the ring 171 closest to the cover 13 and the latter. Preferably, the ring 171 closest to the upper face 15 of the housing 19 is carried by the latter.

[0065] The legs 113 preferably have, in section, a shape corresponding to the shape of the section of the rings 171.

[0066] The legs 113 are carried by an upright 115 of the arm 112 concerned. The rotation of the mobile assembly 11 causes the legs 113 to rotate between the rings 171 in the manner of a fork or a comb whose teeth would be inserted between the rings 171 from the outside.

[0067] In section, the length w 2 (view (C)) of a tab 113 depends on the width w 1 of the rings 171. It is generally equal to the width w 1 of the rings 171. The length w 2 is, for example, between 0.1 and 3 cm, preferably between 1 and 2.5 cm, the length w 2 being preferably equal to approximately 1.5 cm, for example equal to 1.5 cm.

[0068] The width w 3 of a tab 113 is preferably constant. The width w 3 of a tab 113 is chosen according to the dimensions of the rings 171 and the thickness of the gaps between rings 171 in order to be able to rotate freely (with play) between two rings 171.

[0069] The width w 3 is, for example, between 0.1 cm and 1.2 cm, preferably between 0.3 and 1 cm, the width w 3 being preferably approximately equal to 0.8 cm, for example equal to 0.8 cm.

[0070] Alternatively, the legs 113 have disc arc shapes of the same diameter as the rings 171.

[0071] The passage of the legs 113 in the gaps of the baffles makes it possible to eliminate obstacles to the circulation of air, for example, dust, insects, cobwebs, etc.

[0072] For some obstacles, the power of the motor is enough to clear the gaps.

[0073] For other obstacles, the motor force is not sufficient. However, resistance to rotation can be detected and an alarm can be issued informing of a potential malfunction of the detector 1 due to obstruction(s). An operator can then manually drive the moving assembly 11, with a force greater than that of the motor, to remove, detach or unjam the obstruction(s).

[0074] As a particular example of implementation, the motor is programmed to rotate the moving assembly 11 periodically, for example, ten seconds every two hours.

[0075] The surfaces of the legs 113 can also be equipped with brushes in order to rub or brush the surface of the rings 171. This also makes it possible to compensate for any manufacturing tolerances of the rings 171 and to facilitate cleaning. The orientation of the brushes can also allow dust or dirt to be evacuated towards the outside of the baffles, away from the chamber.

[0076] The ends of the legs 113 (inside the chamber) can also be equipped with brushes to scrub and clean the surface of the LED and the photodetector. This also helps to facilitate cleaning and thus reduce false detections.

[0077] In the embodiment of the figure 3 , a second arm 112 of the mobile assembly 11 carries a fin 111.

[0078] The fin 111 is carried by an upright 115 of the arm 112. The rotation of the mobile assembly 11 causes the fin 111 to rotate around the rings 171. The fin 111 has the shape of a curved rectangle, or a sail.

[0079] The fin 111 is fixed to the upright 115 of the arm 112 of the mobile assembly 11 with an angle θ. The angle θ, which corresponds to the angle between the arm 112 of the mobile assembly 11 on which the fin 111 is fixed and the tangent to the base of the fin 111, is for example between 1 and 170°, preferably between 10 and 90°, the angle θ being preferably equal to approximately 50°, for example equal to 50°.

[0080] The curvature of the fin 111, the angle θ and the direction of rotation are designed to generate suction at the baffles. Thus, by rotating, the fin 111 expels the air in front of it. The depression created behind the fin 111 causes suction of the air located inside the chamber. This suction makes it possible to renew the air in the chamber. The sucked air also makes it possible to carry away, as it passes, the dust or deposits present on the rings 171, and thus to unclog the baffles.

[0081] The renewal of the air in the chamber by the fins 111 also has the advantage of avoiding false detections. Indeed, in the event of suspicion of smoke, the renewal of the air in the chamber makes it possible to confirm (or validate) or deny (or invalidate) the presence of smoke.

[0082] For example, when the photodetector detects scattered light, it can trigger a rotation of the moving assembly 11. Renewing the air in the chamber then removes the doubt. If the photodetector no longer detects scattered light, it is because it was a false alarm. Conversely, if the photodetector still receives a beam of scattered light, there is indeed smoke in the environment of detector 1.

[0083] An advantage is that cleaning the baffles, but also renewing the air in the chamber, makes detector 1 more reliable by reducing false alarms.

[0084] In the embodiment of the figure 3 , the two arms 112 carry hoops 117 at their free ends. The hoops 117 provide rigidity to the structure without making it too heavy. The hoops 117 are carried by the uprights 115. The hoops 117 make it possible to detect obstacles close (a few centimeters) to the detector 1. The detection distance depends on the size of the hoops 117 and more precisely on the length (orthogonal to the Z axis) added to the arm 112.

[0085] A removable and extendable rod (not shown) can further be attached to the top of the mobile assembly 11. This rod makes it possible to detect (by rotating) whether objects are present in the environment close to the detector 1 (a few tens of centimeters) to check whether safety distances set by standards are respected. For example, an alarm is emitted in the event of resistance to rotation to indicate that the detector 1 is incorrectly positioned or that objects have been stored too close to it.

[0086] There figure 4 is a perspective representation and by views (A), (B) and (C), partial and schematic, of an embodiment of parts 13 and 15 of the detector 1 of the figure 1 .

[0087] Views (A) and (B) represent the cover 13 and the upper face 15 of the housing 19. View (C) represents the interior of the cover 13.

[0088] The upper face 15 of the housing 19 comprises, among other things, a hollow cylinder 159 in which a motor shaft 1915 passes. The motor shaft 1915 drives, by its rotation, the rotation of the mobile assembly 11 around the Z axis. The mobile assembly 11 is fixed to the motor shaft 1915 at the outlet of the cylinder 159 (above the cover 13). The motor shaft 1915 is connected, in the housing 19, to a motor 1913 (M). The motor is connected to an electronic control circuit 191 (EC). The circuit 191 and / or the motor are powered by a power source 1911 (P). The power source 1911 is, for example, a cell or a battery.

[0089] The upper face 15 further comprises conical bases 152 (four in number on the figure 4 ). The assembly pads 172 of the elements 17 are superimposed on the bases 152. The bases 152 thus make it possible to fix the elements 17 to the housing 19, by its upper face 15. The number of bases 152 is equal to the number of assembly pads 172 present on each of the elements 17 of the detector 1.

[0090] The upper face 15 further comprises a first location 153 for receiving the LED 151 and a second location 157 for receiving the photodetector 155.

[0091] The first location 153 has the shape of a hollow cylinder whose end is located in the frustoconical chamber. The interior of the cylinder is intended to receive the LED 151 which is engaged vertically from the interior of the housing 19.

[0092] The second location 157 has the form of a stud projecting from the upper face 15 and receives the photodetector 155. The photodetector 155 is positioned horizontally (in a plane orthogonal to the Z axis).

[0093] The LED 151 and the photodetector 155 are electrically connected (connections 1510 and 1550) to the electronic control circuit 191 located in the housing 19, and are preferably carried by an electronic card carrying the circuit 191.

[0094] The cover 13 includes, among other things, orifices 132 (four in number on the figure 4 ) which overlap the assembly studs 172. The orifices 132 thus make it possible to fix (for example using screws) the cover 13 to the elements 17 and to the housing 19, via the upper face 15. The number of orifices 132 is equal to the number of bases 152, and thus to the number of assembly studs 172 present on each of the elements 17 of the detector 1.

[0095] The cover 13 further comprises an optical sub-chamber 133. The sub-chamber 133 is, like the optical chamber, black and opaque. The sub-chamber 133 is optically isolated from the chamber by screens in order to reduce the risk of light contamination of the sub-chamber 133 by external light. One 135 of the screens of the sub-chamber 133 is vertical and comprises an orifice 131 placed in front of the photodetector 155. The orifice 131 is arranged such that the photodetector observes, through the orifice 131, the sub-chamber 133 at the top of the location 153, therefore of the LED 151.

[0096] The bases 152 and the internal faces of the orifices 132 are preferably conical and adapted to the respective ends of the studs 172 to facilitate assembly and ensure alignment of the stack of rings 171. In addition, this makes it possible to fix the position of the sub-chamber 133 relative to the LED 151.

[0097] When the smoke detector 1 is in operation, the LED 151 emits a light beam. The light beam is focused thanks to the conical shape of the cylinder 153. In the absence of smoke, the beam is absorbed by the screens of the black sub-chamber 133 and the photodetector 155 does not detect any light. In the presence of smoke, particles are suspended in the air of the chamber and the beam emitted by the LED 151 is scattered by the smoke particles. The photodetector 155 then detects, through the orifice 131, scattered (indirect) light. The photodetector 155 electrically transmits, to the electronic circuit 191, information representative of the intensity of the light signal received.

[0098] There figure 5 is a partial and schematic side view of an embodiment of the detector of the figure 1 . More precisely this figure 5 represents parts 11, 13, 15, 17 of the smoke detector 1 of the figure 1 .

[0099] This figure highlights the respective dimensions between the different elements.

[0100] As an example of an embodiment, a detector 1 may have the following dimensions: the diameter D 1 of the housing 19 is between 3 and 20 cm, preferably between 5 and 15 cm, the diameter D 1 being preferably equal to approximately 9 cm, for example equal to 9 cm; the external diameter D 2 of the stack of elements 17, or external diameter of the rings 171, is between 3 and 20 cm, preferably between 5 and 15 cm, the diameter D 2 being preferably equal to approximately 7 cm, for example equal to 7 cm; the length L of the mobile assembly 11 is greater than the diameter D 2 - this length L is between 3 and 30 cm, preferably between 5 and 15 cm, the length L being preferably equal to approximately 13 cm, for example equal to 13 cm; the height H 1 of the stack of elements 17 depends on the number of rings 171 in the stack, the height of a ring 171 and the spacing between two rings 171 - this height H 1 is between 0.5 and 15 cm, preferably between 1 and 5 cm, the height H 1 being preferably equal to approximately 3 cm, for example equal to 3 cm;the height H 2 of the detector 1, excluding the housing 19, is between 1 and 20 cm, preferably between 2 and 10 cm, the height H 2 being preferably equal to approximately 5 cm, for example equal to 5 cm; and the height H 3 of the housing 19 is between 1 and 10 cm, preferably between 1 and 8 cm, the height H 3 being preferably equal to approximately 3 cm, for example equal to 3 cm.;

[0101] There figure 6 is a representation, by views (A) and (B), partial and schematic, respectively in perspective and in section of another embodiment of a smoke detector 2.

[0102] The detector 2 comprises, among other things, a housing 29, an upper face 25 of which carries a stack of elements 27.

[0103] The embodiment shown in figure 6 differs from the embodiment described in connection with the figure 1 by the fact that the cleaning of the baffles is carried out by an assembly 21 inside the chamber. The assembly 21 is equipped with a module of legs 213 similar to the legs 113 of the mobile assembly 11 of the detector 1 of the figure 1 The legs 213 are fixed to the upper face 25 of the housing by a bracket 215 resting (foot 298) on the housing 29. The legs 213 of the assembly 21 move in the interstices formed between rings 271 of the elements 27. The assembly 21, in the embodiment of the figure 6 , is fixed and the stack of elements 27 is movable. The stack of elements 27 is, for example, fixed to one or more structures 297.

[0104] Each structure 297 has, for example, an inverted "U" shape. The number of structures is chosen in order to allow the maximum possible air passages while ensuring the mechanical strength of the rings 271. The structures are connected, by a motor shaft 295, to a motor 293 (placed in the housing 29). The motor 293 generates the rotation of the stack 27, by the motor shaft 295 and the structure(s) 297.

[0105] Each structure 297 is fixed, for example, to all of the rings 271 of the stack, by attachment points 299 located outside the base of the rings 271.

[0106] In this embodiment, the elements 27 do not comprise assembly studs. The spacing between the rings 271 is, for example, fixed by the spacing between the attachment points 299. The space between the attachment points is for example between 0.1 and 3 cm, preferably between 0.5 and 1.5 cm and is preferably equal to approximately 0.7 cm, for example equal to 0.7 cm.

[0107] In another embodiment not shown, it is possible to envisage imposing different distances between the rings 271. The spacing between the attachment points is then variable.

[0108] Alternatively, the rings 271 are fixed to each other by studs (not shown in figure 6 ) connecting them together in their section.

[0109] For example, brushes (not shown in figure 6 ) at the outer ends of the legs 213 and fix an insect and dust-proof grid to the stack of elements 27. The rotation of the grid, driven by the rotation of the stack, causes the brushes to rub against the grid and therefore clean it.

[0110] All or part of the variants to the embodiment of the figure 1 apply to the embodiment of the figure 6 . In particular, it is possible to envisage fixing to the end of a leg 213 of the assembly 21, a ventilation fin similar to the fin 111 of the detector 1 shown in figure 3 .

[0111] There figure 7 is a representation, by partial and schematic perspective views (A) and (B), of another embodiment of a smoke detector 3, not covered by the invention.

[0112] The detector 3 comprises, among other things, a housing composed of a mobile part 31 and a fixed part 32.

[0113] The movable part 31 corresponds to a cylinder, the lateral face of which comprises a succession of vertical angular walls 311 defining indirect passages or baffles from the exterior to an optical chamber present inside said cylinder. All of these baffles form a baffle system.

[0114] The fixed part 32 corresponds to another cylinder. The fixed part 32 forms a receiving ring for the movable part 31. The inner lateral surface of the fixed part 32 is provided with walls 321 having substantially the same shape as the baffles so that the movable part 31 can slide vertically in the fixed part 32.

[0115] In the embodiment illustrated in figure 7, the sliding movement of the movable part in the fixed part makes it possible to clean the baffles. More particularly, the sliding of the walls 321 of the fixed part 32 in the baffles of the movable part 31 makes it possible to clear the baffles of any obstructions.

[0116] Cleaning is carried out, for example, by manual action on part 31 so as to push it into part 32, against an elastic return force caused by a spring.

[0117] An advantage of the described embodiments and implementations is the increase in the reliability of the detector by the possibility of fully testing its detection system and its environment.

[0118] Another advantage of the described embodiments and implementations is the ability of the detector to self-clean.

[0119] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will occur to those skilled in the art.

[0120] Finally, the practical implementation of the embodiments and variants described is within the reach of those skilled in the art from the functional indications given above.

Claims

1. A smoke detector (1; 2) comprising: a detection chamber; a baffle system surrounding the chamber, enabling to isolate the chamber from outer light and enabling air to flow from the outside to the inside of the chamber; and a mechanical actuator capable of cleaning, in case of obstacles to air circulation, the baffles, the smoke detector being characterized in that baffles are created by a successive stacking of elements (17; 27), each comprising a ring (171; 271).

2. The detector according to claim 1, comprising a device adapted to detect resistance to the rotation of a motor of the actuator and emit an alarm when the force of the actuator motor is not sufficient to clean the baffles.

3. The detector according to claim 1 or 2, wherein the cross-section of the rings (171; 271) has a general "U" or "V" shape.

4. The detector according to any of claims 1 to 3, further comprising: a housing (19; 29) receiving said elements (17; 27); and a cover (13) closing the stack opposite to the package (19; 29), to close the chamber.

5. The detector according to any of claims 1 to 4, further comprising an assembly (11; 21) of tabs (113; 213) interposed between two successive rings (171; 271), each tab (113; 213) having a general shape corresponding to the general shape of the cross-section of the rings (171; 271).

6. The detector according to claims 4 and 5, wherein the assembly (11; 22) is supported by the housing (19; 29).

7. The detector according to claim 5 or 6, wherein the assembly (11; 21) comprises one or a plurality of blades (111) external to the rings (171; 271).

8. The detector according to any of claims 5 to 7, wherein the assembly (11) rotates around the axial direction of the stack.

9. The detector according to claim 8, wherein the assembly (11) is driven by a motor (1913).

10. The detector according to any of claims 5 to 9, wherein the assembly (11) is external to the chamber.

11. The detector according to any of claims 5 to 7, wherein the assembly (21) is fixed.

12. The detector according to any of claims 5 to 7 and 11, wherein the rings (271) are mobile and rotate around the axial direction of the stack.

13. The detector according to claim 12, wherein the stack is driven by a motor (293).

14. The detector according to any of claims 5 to 7 and 11 to 13, wherein the assembly (21) is internal to the chamber.

15. The detector according to any of claims 5 to 14, wherein the tabs (113; 213) are equipped with brushes and the stack is equipped with an external insect and dust grid, the grid being cleaned by the brushes during the rotation of the stack.

16. The detector according to any of claim 1 to 15, further comprising an electronic control circuit (191).

17. The detector according to any of claim 1 to 16, comprising, in the chamber, a light-emitting diode (151) and a photodetector (155).