SMOKE DETECTOR FOR STRAIGHT-WISE DETECTION OF SMOKE, AND VEHICLE HAVING A SMOKE DETECTOR

Description

Technical area

[0001] The present invention relates to a smoke detector for the detection of smoke in sections, in particular for height-independent detection of smoke in sections, for example in vehicles and in buildings. Previously known state of the art

[0002] Electronic smoke detectors usually have a transmitter and a receiver, with the triggering of the smoke detector signal depending on the presence of smoke.

[0003] Photo-optical smoke detectors are particularly commonly used, with the transmitter comprising a special LED and the receiver a light-sensitive resistor. For example, such a smoke detector can be configured so that a light beam emitted by the transmitter only reaches the receiver when smoke particles scatter or deflect it.

[0004] The US patent US 6,831,289 discloses a detection device for scattered light as part of a hazard detector, such as a fire alarm system.

[0005] EP 0756703 A1 discloses a device comprising an elongated chamber serving as a channel for a carrier medium and having light sources embedded in its walls and a coaxial light detector at one end for measuring light dispersion to detect the density, size or distribution of particles in a gas stream. Disadvantages of the state of the art

[0006] However, such smoke detectors do not provide satisfactory results if the smoke is not directly at or within the smoke detector, as these smoke detectors only detect smoke at specific points. Therefore, an alarm can only be triggered if the smoke has already spread to the smoke detector, which usually means it has penetrated into the ceiling. Furthermore, due to the localized nature of smoke detection, equipping large rooms with the goal of comprehensive monitoring can be expected to be more expensive. This is all the more true since such smoke detectors involve complex components for which special injection-molded parts must be manufactured in large series. Problem

[0007] The object of the present invention is therefore to provide a smoke detector which enables the detection of smoke over larger areas in order to be able to detect smoke not only locally at one point, but continuously over the length of a room. Inventive solution

[0008] The above object is achieved according to one embodiment by a smoke detector according to claim 1. Further advantageous embodiments are specified in the subclaims.

[0009] According to the invention, the smoke detector comprises a first and a second chamber. These chambers are elongated to enable smoke detection beyond a single point. For this purpose, the first and second chambers of the smoke detector according to the invention extend along a common longitudinal direction.

[0010] In contrast to the designs described here, conventional smoke detectors comprise a cavity that is only a few millimeters high. A labyrinth with narrow gaps surrounds such a cavity to prevent outside light from penetrating. If smoke penetrates the labyrinth into the cavity, a light beam emitted by a transmitter, for example, is scattered and possibly directed to a receiver, triggering an alarm. Such a conventional smoke detector is limited to detecting smoke within a narrow radius of the smoke detector's installation location. If the smoke is not directly at or in the smoke detector, no alarm is triggered.

[0011] In contrast, smoke detectors according to the embodiments described here can detect smoke along the entire length of the smoke detector, for example, when mounted along cables or various electrical components. The smoke detector can, for example, extend over the entire length of a room to be monitored, for example, along cable ducts or along the ceiling of installation rooms, and thus monitor the entire room.

[0012] Furthermore, vertical or angled installation of the smoke detector according to the invention allows, for example, a smoldering fire creeping along the floor to be detected just as quickly as "hot" smoke accumulating on the ceiling. In the case of constant or unpredictable air movement, such as "stagnant" air, smoke along the inventive, elongated smoke detector is thus detected earlier than with a conventional smoke detector, which can only detect a small spatial area.

[0013] Furthermore, the smoke detector has a first wall with at least one, two, three, or more first openings. The first wall at least partially delimits the first room. In this sense, the term "at least partially" is to be understood to mean that the entire perimeter of the first room is not necessarily described by the first wall. For example, the first wall can extend only over an area corresponding to 50%, 60%, 70%, 80%, or 90% of the total perimeter of the first room. Thus, for example, a cylindrical first room can be delimited as such a first wall only over the area whose points from its axis have the same radius. Furthermore, a cuboid first room, for example, can be delimited by the first wall only on two, three, or four of its side surfaces.

[0014] The one, two, three or more first openings within the first wall allow smoke to enter the first room of the smoke detector at the positions of the first openings and thus at one, two, three or more different positions along the longitudinal direction of the smoke detector.

[0015] Furthermore, the smoke detector has a second wall separating the first room from a second room, which in turn comprises at least one, two, three, or more second openings. The first room is connected to the second room via the one, two, three, or more second openings. For example, such a second wall can run within the first room and thus span a second room within the first room. Likewise, the second wall can extend between a first room and a second room running parallel to it, thus separating the first room from the second room.

[0016] The at least one, two, three, or more second openings in the second wall enable gas exchange between the first chamber and the second chamber. Thus, smoke, for example, can move from outside through the first opening(s), through the first chamber, through the second opening(s), and into the second chamber.

[0017] In addition, the smoke detector has a transmitter and a receiver, whereby under normal conditions, i.e. without the presence of smoke, a signal transmitted by the transmitter cannot easily reach the receiver and therefore no alarm is triggered under normal conditions. The second wall separates the transmitter from the receiver. For example, the smoke detector can have a transmitter in one of the two rooms and a receiver in the other of the two rooms. In this case, the transmitter can be located in the first room and the receiver in the second room. When selecting the position of the receiver within the smoke detector, the design-related exposure of the receiver to unwanted external interference signals is advantageously taken into account. A receiver is preferably located outside of possible angles of incidence of external radiation, i.e. external interference signals that are not emitted by the transmitter.For example, the receiver can be arranged in an inner second space, while the transmitter is located in an outer first space. The transmitter and receiver are preferably an optical transmitter and an optical receiver.

[0018] A transmitter can, for example, be provided by a special light-emitting diode or laser diode, wherein the signal from the transmitter is based on optical radiation. A receiver can, for example, be provided by a light-sensitive resistor that can detect such optical radiation. As described above, when designing the smoke detector, it must be ensured that the optical radiation emitted by the transmitter cannot hit the receiver directly. In contrast, the presence of smoke, which can move through the at least one first opening, through the first space, through the at least one second opening and through the second space, causes the optical radiation emitted by the transmitter to be deflected by smoke particles in its beam path. Depending on the position(s) of the first or second opening(s), the optical radiation can be deflected by smoke particles in its beam path.Depending on the size of the second opening(s) and the type and quantity of smoke particles, the transmitter's optical radiation can be at least partially redirected toward the receiver and thus detected by it. In this case, the smoke detector triggers an alarm indicating smoke development. Such triggering of the alarm can be dependent on the signal intensity detected by the receiver exceeding a predetermined threshold.

[0019] According to one embodiment of the smoke detector according to the invention, the second chamber is arranged within the first chamber of the smoke detector. The first chamber can at least partially surround the second chamber. A partial, i.e., incomplete, surround of the second chamber by the first chamber can result, for example, from different lengths of the first and second chambers. Likewise, the first chamber can also substantially completely surround the second chamber, although the end faces of the second chamber do not necessarily have to be surrounded by the first chamber.

[0020] According to a further embodiment of the smoke detector according to the invention, the lengths of the first and second rooms each correspond to at least twice the combined width of the first and second rooms, respectively. Preferably, the length of the first and second rooms corresponds to at least three times, particularly preferably at least four times, five times, or ten times the combined width of the first and second rooms. The smoke detector therefore preferably has an elongated shape, for example a tube, and can therefore be provided in any length. It is therefore possible to adapt the length of the smoke detector to the length of the room to be monitored. This means that even larger areas can be monitored, in contrast to previous smoke detectors. The smoke detector can, for example, have a length of at least 50 cm, typically at least 1 m.

[0021] According to a preferred embodiment, the first and second chambers of the smoke detector according to the invention are approximately the same length. In this case, the person skilled in the art understands approximately the same length to mean that the length deviations are within a design-related tolerance range.

[0022] According to a further embodiment, the smoke detector according to the invention extends from a first end in the longitudinal direction to a second end in the longitudinal direction. The transmitter and receiver can be arranged, for example, at opposite ends of the smoke detector. Alternatively, the transmitter and receiver can be arranged at the same end of the smoke detector. Such a design allows, for example, the smoke detector to be equipped with electrical connections at only one of its two ends.

[0023] Furthermore, a smoke detector according to the invention can have a first and a second chamber, each with two opposite end openings. The opposite end openings are located, for example, within the outer sectional planes bounding the first chamber and the second chamber, respectively, with the longitudinal axis of the first and second chambers, respectively. These end openings can also be closed by one or more closure elements. A closure element thus at least partially closes such an end opening. This prevents, for example, the penetration of unwanted external interference signals through the end openings at the ends of the smoke detector.

[0024] Preferably, the smoke detector's transmitter and receiver are each located in a separate closure element. Alternatively, the transmitter and receiver can also be located within a single closure element.

[0025] As previously described, according to one embodiment, the first chamber of the smoke detector can be delimited on the outside by the first wall and on the inside by the second wall. Such a structure is made possible, for example, by the second chamber extending within the first chamber. A parallel arrangement of the first and second chambers next to one another is also possible. In both embodiments, however, the at least one or more second openings in the second wall are preferably offset from the at least one or more first openings in the first wall. Such an offset of the first and second opening(s) is preferably configured to prevent external scattered light from reaching the smoke detector's receiver. This prevents unwanted external interference from affecting the receiver, thus preventing a false alarm from being triggered.Such an arrangement of the openings is particularly advantageous if the transmitter and receiver are located on different sides of the smoke detector.

[0026] Such an arrangement can be achieved, for example, by arranging the second openings in the second wall and the first openings in the first wall at different positions along the longitudinal axis of the smoke detector. Depending on the particular embodiment of the smoke detector, an arrangement in which the second openings point in a different direction than the first openings is also advantageous. The direction of a first or second opening is defined, for example, by the angle between the normal vector of the respective opening area and the longitudinal center plane of the smoke detector. For example, the first or second openings can be arranged on different sides along the longitudinal direction of the smoke detector. If the first or second openings are on exactly opposite sides along the longitudinal direction of the smoke detector, the difference in their directional angles as defined above is 180 degrees.The directions of the one, two, or more first or second openings may be the same or different.

[0027] Furthermore, according to a further embodiment, some or all of the first openings in the first wall can be provided with a filter. Such a filter is permeable to smoke, but prevents, for example, small animals and insects such as spiders, mites, or wasps from nesting in the smoke detector and thus interfering with smoke detection.

[0028] According to a preferred embodiment, the second wall is formed by an inner tube and the first wall is formed by an outer tube surrounding the inner tube. As a result, the second space is delimited by the inner tube and the first space is provided by the space located between the inner tube and the outer tube. Preferably, the outer tube and the inner tube are delimited at their respective ends by closure elements. For example, one of the closure elements can contain the transmitter and the opposite closure element can contain the receiver. A construction in which the inner tube is held within the outer tube by the closure elements is particularly preferred.

[0029] Furthermore, in this preferred embodiment, the inner tube can have a plurality of openings that form the plurality of second openings in the second wall. At the same time, the outer tube can have a plurality of openings that form the plurality of first openings in the first wall. Preferably, the openings in the outer tube point within a first radial angle range relative to the longitudinal axis of the outer tube, and the openings in the inner tube point within a second radial angle range relative to the longitudinal axis of the outer tube, which does not overlap with the first radial angle range. The two radial angle ranges therefore point in different radial directions relative to the longitudinal axis. Such a design ensures that external scattered light cannot directly strike the smoke detector and the surface of the receiver, which would negatively impact smoke detection and possibly trigger a false alarm.

[0030] The embodiments described above can be combined with each other as desired. Short description of the characters

[0031] The accompanying drawings illustrate embodiments and, together with the description, serve to explain the principles of the invention. The elements of the drawings are relative to one another and are not necessarily to scale.

[0032] The same reference symbols indicate the same or similar parts. The Figure 1 shows a schematic view of a smoke detector in longitudinal section. Figures 2 and 3 show a spatial, schematic view of a closure element with a transmitter and a receiver, respectively, according to an embodiment. Figures 4A to 4C and 5A and 5B show, according to one embodiment, a spatial, schematic view of a tubular smoke detector ( Figure 4A ) with an outer tube ( Figure 4B ), an inner tube ( Figure 4C), a first closure element ( Figure 5A ) and a second closure element ( Figure 5B ). The Figure 6 shows a spatial, schematic view of an embodiment of the smoke detector in an open state. Figure 7 shows a schematic view of a smoke detector according to another embodiment in longitudinal section. Figure 8 shows a spatial, schematic view of a closure element with a transmitter and a receiver according to another embodiment. Figure 9 shows a spatial, schematic view of a smoke detector according to another embodiment. Examples of implementation

[0033] To clarify the overall understanding, a schematic view is used in Figure 1 A smoke detector 100 according to the invention is shown in cross-section. This comprises an elongated first chamber 110 and an elongated second chamber 120. Figure 1illustrates an embodiment of the invention in which the second space 120 extends tubularly within the first tubular space 110 along a common longitudinal direction and a common longitudinal axis. The second space 120 is delimited or defined by a second wall 121, and the first space 110 is delimited or defined by a first wall 111 and the second wall 121. Furthermore, in the Figure 1In the embodiment shown, both the first and the second wall each have a plurality of openings 151, 152, which can be arranged, for example, evenly distributed along the entire extent of the respective first and second spaces 110, 120. The number of openings 152 between the first and second spaces 110, 120 and the number of openings 151 between the first space 110 and the outside environment can be the same, but can also be different. Furthermore, it is possible for the opening cross-section of the openings 151, 152 to be different. However, it can also be the same for all openings 151, 152.

[0034] By way of example, the cover with filters 190 is shown for some of the first openings 151 in the first wall 111. Figure 1At the left first end 160 of the smoke detector 100 constructed in this way, a first end opening 112 is located within the first space 110 with a transmitter 130 arranged therein. This transmitter transmits optical radiation, for example in the visible or near infrared range, only into the first space 110 parallel to the longitudinal axis, but not directly into the second space 120. At the end shown in the Figure 1 The right second end 170 of the smoke detector 100 constructed in this way, shown, has a second end opening 122 within the second space 120 with a receiver 140 arranged therein. Figure 1 further shows that the smoke detector in the embodiment shown has a length l which corresponds to a multiple of its radius r, in the case of a circular cross-section, or its maximum width, in the case of any other cross-section.

[0035] Figures 2 and 3 illustrate in schematic views two closure elements 180a, 180b, which are connected to the Figure 1 shown embodiment of a smoke detector 100 according to the invention. Thus, the Figure 2 The closure element 180a shown comprises a ring-shaped transmitter 130, or a transmitter 130 that is arranged only in the ring area around the second space 120. It is also possible for several transmitters 130 to be arranged in a ring. The closure element 180a with the transmitter 130 is adapted to close the first space 110 of the smoke detector 100 from Figure 1 at one of its end openings 112. In contrast, the Figure 3 The closure element 180b shown has a receiver 140 within the second space 120, or at one of its ends, and due to its cylindrical structure is suitable for closing the second space 120 of the smoke detector 100 from Figure 1 to close one of its end openings 122.

[0036] Figure 4Ashows a spatial representation of a tubular elongated smoke detector, which has an outer tube 101 and an inner tube 102, which runs, for example, coaxially to the outer tube 101. The outer tube 101 is in Figure 4B and the inner tube 102 is in Figure 4C The jacket wall 111 of the outer tube 101 forms a first wall, while the jacket wall 121 of the inner tube 102 forms a second wall. The second space 120 is bounded by the interior region of the inner tube 102, while the first space 110 is bounded by the jacket wall 111 of the outer tube 101 and the jacket wall 121 of the inner tube 102. The first space 110 therefore surrounds the second space 120.

[0037] Both the inner tube 102 and the outer tube 101 each have a plurality of openings 151, 152. The openings 151 (first openings) of the outer tube 101 are shown in Figure 4Bupwards, the openings 152 (second openings) of the inner tube 102 point toward the observer, i.e., they are arranged rotated about the longitudinal axis relative to the openings 151 of the outer tube 101. As a result, light cannot pass directly through the openings 151, 152 into the interior of the inner tube 102, i.e., into the second space 120.

[0038] In addition to the plurality of first openings 151, the outer tube 101 has two opposite end openings 112. Likewise, the inner tube 102 has two opposite end openings 122 in addition to the second openings 151.

[0039] The inner tube 102 is closed by a first closure element 181 and a wide closure element 182, which are Figures 5A and 5Bare shown, held within the outer tube 101. The closure elements 181, 182 additionally close the respective end openings 112, 122. For example, the second closure element 182 can have a shoulder 183 on its outer side, onto which the outer tube 101 is slid, for example, in a form-fitting manner. One or more transmitters can be arranged on the end face 184 of the second closure element 182, which transmitters radiate in the axial direction, i.e., within and along the outer tube 101. Specifically, the transmitter or transmitters radiate into the first space 110, which is annular in cross-section and extends between the inner tube 102 and the outer tube 101.

[0040] The inner tube 102 is then inserted into the inner opening 185 of the second closure element 182 and held in place by the inner opening 185, for example, in a form-fitting manner. This keeps the inner tube 102 spaced apart from the outer tube 101. The transmitters radiate into the space between the inner tube 102 and the outer tube 101, i.e., into the first space 110.

[0041] The first closure element 181 also has an inner opening 185 into which the inner tube 102 is inserted with a form-fitting fit. A receiver is located within the inner opening 185 of the first closure element 181. Radiation emitted by the transmitter(s) of the second closure element 182 does not reach the receiver directly, since the direct path through the inner tube 101 is blocked. However, if smoke or an aerosol penetrates through the first openings 151 of the outer tube 101 into the space between the outer tube 101 and the inner tube 102 and possibly further through the second openings 152 of the inner tube 102 into the interior of the inner tube 102, the radiation emitted by the transmitter is scattered by the smoke or aerosol particles and thus also reaches the interior of the inner tube 102 and ultimately the transmitter in the first closure part 181.The scattered light is registered by the receiver, evaluated by suitable electronics and emitted as a warning signal.

[0042] The first closure element 181 can, for example, be inserted into the outer tube 101 in a form-fitting manner. However, it can also have a step like the second closure element 182, onto which the outer tube 101 can be pushed.

[0043] Figure 6 illustrates how the Figure 1 shown embodiment by inserting the Figure 5 shown second wall 121 into the Figure 4 shown first wall 111 can be assembled. Furthermore, Figure 6 schematic of an electronics for controlling the transmitter and the receiver.

[0044] Figure 7 shows an alternative embodiment to that shown in Figure 1 illustrated embodiment of the present invention. In this case, as shown in Figure 1shown, the transmitter 130 in a first room 110 of the smoke detector 100 and the receiver 140 in a second room 120 of the smoke detector 100. The Figure 7 However, the alternative embodiment listed differs from the one in Figure 1 illustrated structure in that both the transmitter 130 and the receiver 140 are arranged in the respective end openings 112, 122 at the same end of the illustrated smoke detector 100.

[0045] The Figure 7 The alternative embodiment shown can be connected to a device as shown in Figure 8 shown closure element 180. In contrast to the Figures 2 and 3 The closure elements 180a, 180b shown in Figure 8 The schematic view shown shows a closure element 180 which has both a transmitter 130 in an outer annular region and a receiver 140 in an inner cylindrical region of the closure element 180.

[0046] Figure 9 shows a further alternative embodiment to that shown in Figure 1 illustrated embodiment of the present invention. In this case, as shown in Figure 1 As shown, the transmitter 230 is located at an end opening of a first chamber 210 of the smoke detector 200, and the receiver 240 is located at an opposite end opening 222 of a second chamber 220 of the smoke detector 200. The first chamber 210 is connected to the environment via a plurality of first openings 251 in one of its walls 211 (first wall). The first chamber 210 and the second chamber 220 are separated from one another by a second wall 221. The second wall 221 has a plurality of second openings 252, which are offset from the first openings 251 in the first wall 211, so that no direct light from outside can enter the second chamber 220.

[0047] The Figure 9 However, the alternative embodiment listed differs from the one in Figure 1 and Figure 7 shown structure insofar as the second space 220 runs next to and parallel to the first space 210 and not within the first space 210. In addition to the Figure 9 In addition to the arrangement of the transmitter 230 and the receiver 240 at opposite ends 212, 222 of the smoke detector 200 shown in FIG. 1, a structure corresponding to the arrangement shown in FIG. Figure 7 An alternative embodiment is possible, i.e., an arrangement of the transmitter 230 and the receiver 240 at ends of the first chamber 210 and the second chamber 220, which are located at the same end of the smoke detector 200. Optionally, some or all of the first openings 251 can be closed with a filter 290.

[0048] Further embodiments of the present invention include installation spaces in passenger compartments of rail vehicles, ships, aircraft, or buses equipped with the embodiments of the smoke detector 100, 200 shown in the figures. A smoke detector 100, 200 is preferably arranged along cable harnesses or cable areas within the passenger compartments.

[0049] Furthermore, kitchens, industrial halls, warehouses or archives equipped with the smoke detectors 100, 200 according to the invention represent further embodiments of the present invention. List of reference symbols

[0050] 100, 200 Smoke detector 101 Outer pipe 102 Inner pipe 110, 210 First room 111, 211 First wall 112, 212 End opening 120, 220 Second room 121, 221 Second wall 122, 222 End opening 130, 230 Transmitter 140, 240 Receiver 151 First opening 152 Second opening 160 First end 170 Second end 180, 180a, 180b Closure element 181, 182 Closure element 183 Shoulder 184 Front end 185 Inner opening 190, 290 Filter 195 Electronics l Length of the smoke detector r Radius of the smoke detector

Claims

1. Smoke detector, comprising an elongated first space (110, 210) and an elongated second space (120, 220), the first space (110, 210) and the second space (120, 220) extending along a common longitudinal direction; a first wall (111, 211) comprising at least one, preferably several, first openings (151, 251), wherein the first wall (111, 211) at least partially delimits the first space (110, 210) so that smoke can enter the first space (110, 210) of the smoke detector (100, 200) at different positions along the longitudinal direction of the smoke detector (100, 200); a second wall (121, 221) separating the first space (110, 210) from the second space (120, 220) and having at least one, preferably several, second openings (152, 252), the first space (110, 210) being connected to the second space (120, 220) via the one or several second openings (152, 252) so that gas exchange can take place between the first space (110, 210) and the second space (120, 220) and between the first space (110, 220) and the environment; a transmitter (130, 230) in one of the two spaces (110, 120, 210, 220) for emitting optical radiation; and an optical receiver (140, 240) in the other of the two spaces (110, 120, 210, 220) for receiving the optical radiation.

2. Smoke detector according to claim 1, wherein the second space (120) is located within the first space (110), and the first space (110) at least partially surrounds the second space (120).

3. A smoke detector according to any one of the preceding claims, wherein the length (l) of the first and second spaces (110, 120, 210, 220) corresponds to at least their common double width, in particular at least their common triple width, and in particular at least their common quadruple width.

4. Smoke detector according to one of the previous claims, wherein the smoke detector extends from first end (160) in longitudinal direction to a second end (170) in longitudinal direction, wherein the transmitter (130) and the receiver (140) are arranged at the same end (160, 170) of the smoke detector or at opposite ends (160, 170) of the smoke detector.

5. Smoke detector according to any one of the preceding claims, wherein the first space (110, 210) and the second space (120, 220) each have two opposite end openings (112, 122, 212, 222) which are each closed by a closure element (180, 180a, 180b, 181, 182), the transmitter (130, 230) and receiver (140, 240) being arranged in one of the two closure elements (180) or separately in one of the two closure elements (180a, 180b, 181, 182), respectively.

6. Smoke detector according to any of the previous claims, wherein the first space (110) is delimited externally by the first wall (111) and internally by the second wall (121).

7. Smoke detector according to any one of the preceding claims, wherein the at least one or several second openings (152, 252) of the second wall (121, 221) are arranged offset with respect to the at least one or several first openings (151) of the first wall (111, 211), in particular pointing in different directions, so that interference of the receiver (140, 240) by external stray light is prevented, preferably the at least one or the several of second openings (152, 252) of the second wall (121, 221) and the at least one or the several of first openings (151, 251) of the first wall (111, 211) being arranged on different sides along the longitudinal direction.

8. Smoke detector according to any one of the preceding claims, wherein the at least one or several second openings (152, 252) of the second wall (121, 221) and the at least one or several first openings (151, 251) of the first wall (111, 211) are arranged offset in such a way that a direct incidence of optical radiation from the transmitter (130, 230) onto the receiver (140, 240) is prevented.

9. Smoke detector according to any one of the preceding claims, wherein the at least one or several first openings (151, 251) of the first wall (111, 211) are provided with a filter (190, 290).

10. Smoke detector according to any one of the preceding claims, wherein the second wall (121) is formed by an inner tube (102) and the first wall (111) is formed by an outer tube (101) surrounding the inner tube (102), the second space (120) being delimited by the inner tube (102), and the first space (110) being the space located between the inner tube (102) and the outer tube (101).

11. Smoke detector according to claim 10, wherein the outer tube (101) and the inner tube (102) are delimited at their respective ends by closure elements (180a, 180b, 181, 182), one of the closure elements (180a, 180b, 181, 182) comprising the transmitter (130) and the other of the closure elements (180a, 180b, 181, 182) comprising the receiver (140).

12. Smoke detector according to claim 11, wherein the inner tube (102) is held by the closure elements (180, 180a, 180b, 181, 182) within the outer tube (101).

13. Smoke detector according to any one of claims 11 to 12, wherein said inner tube (102) comprises a plurality of openings (152) forming the several second openings (152) of the second wall (121), and wherein the outer tube (101) comprises a plurality of openings (151) forming the several first openings (151) of the first wall (111), wherein the openings (151) of the outer tube (101) face a first radial angular range with respect to the longitudinal axis of the outer tube (101) and the openings (152) of the inner tube (102) face a second radial angular range with respect to the longitudinal axis of the outer tube (101) which does not overlap with the first radial angular range.

14. Vehicle, in particular rail vehicle, comprising at least one smoke detector (100, 200) according to one of the previous claims.

15. Vehicle according to claim 14, wherein the smoke detector (100, 200) is arranged in a passenger compartment or in an installation space within the vehicle separate from the passenger compartment.