JP2004355664A - Fire detector for tunnel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate replacement of a fire detector and realize easy and sure waterproofing. <P>SOLUTION: A fire detector for a tunnel is provided with fitting parts 12 having a screw hole and projecting at two or more positions around a detector body 2b, and fastening parts 13 lowered toward the detector body 2b and having through-holes 13a for screws around a cover 2a of the detector body 2b. The fastening parts 13 are provided with a fitting screw hole 13a, through which a screw is screwed into the fitting part 12 to be fixed with a screw head being positioned below the surface of the detector. Projections 16 thrusting over the position to cover both sides of the screw head are formed on the fastening parts 13 provided around the cover 2a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a fire detector for a tunnel that is attached to a storage box installed in a tunnel and monitors a fire.

  As a conventional fire detector for a tunnel, for example, there is one shown in FIG. 13 (JP-A-7-160969). The fire detector 102 is installed on a side wall or the like in the tunnel while being mounted in the storage box 101, and monitors a fire in the longitudinal direction of the tunnel on both sides from the position of the fire detector 102.

  To the fire detector 102 mounted in the storage box 101, a signal line 103 for lead-in from a disaster prevention receiver or the like and a signal line 107 for lead-out to the next fire detector are connected. That is, the leading-in signal line 103 is twisted at the ends of the signal lines with the signal line 104 from the fire detector 102, soldered up, and connected together by a crimp connection portion 105 which is crimped into one. The leading signal line 107 is connected to the signal line 106 from the fire detector 102 by twisting the ends of the signal lines, soldering them up, and crimping them into a single crimping connection unit 108.

Each of the signal lines 103, 104, 106, and 107 is a bundle of a plurality of signal lines, and the crimp connection portions 105 and 108 perform crimping by the number of the plurality of signal lines.
JP-A-9-282578 JP-A-7-160969 JP 2000-133365 A Microfilm of Japanese Utility Model Application No. 62-125118 (Japanese Utility Model Application Laid-Open No. 9-282578)

  However, in such a conventional fire detector for a tunnel, when the fire detector 102 is replaced due to a failure or the like, the signal lines are cut at the crimping connection portions 105 and 108, and then the tip of each signal line is cut off. After stripping the wire, the crimp connection will be made again with the signal wire from the new fire detector. For this reason, there is a problem that it takes time and effort to replace the fire detector, and furthermore, each time the fire detector is replaced, the lead-in signal line 103 and the lead-out signal line 107 become shorter.

  Then, in order to solve such a problem, there is a tunnel fire detection shown in FIG. 14 (Patent Document 2). In this fire detector 111, a detector signal line 112 with a connector with a connector 113 attached thereto is drawn out from the detector main body, and a signal line 115 with a connector with a connector 114 attached thereto is connected. The ends of each of the signal lines 115 and the lead-out signal lines 107 are twisted, soldered up, and connected together by a crimp connection portion 116 which is crimped together. For this reason, the number of parts increases, but when replacing the fire detector 111, the replacement can be easily performed only by removing the connectors 113 and 114.

  However, in a fire detector for a tunnel using this connector connection, as a portion requiring a waterproofing treatment, a connection part A between the connector A and the lead-in portion A of the detector-equipped detector signal line 112 with respect to the detector body is required. There are three parts, a part B and a part C of the crimp connection part 116 of each signal line, and the number of places requiring waterproof treatment increases. In particular, the lead-out portion A of the detector-equipped detector signal line 112 with respect to the detector main body is subjected to waterproofing by potting in which an epoxy resin or the like is poured and fixed, and the waterproofing by potting is technically advanced, and cost is high. There is a problem that also becomes high.

  In the prior art shown in FIG. 13 as well, waterproofing by potting is performed on the lead-in part A1 of the signal line 104 and the lead-in part A2 of the signal line 106 with respect to the fire detector 102.

  Furthermore, the fire detector for tunnels originally has a sealed structure, and has an easily replaceable structure provided with a waterproof connector so that the fire detector itself can be replaced in the event of a failure. Therefore, it is not usually planned to remove the cover at the site when a failure occurs and inspect the inside. However, depending on the situation, the inside may be inspected with the cover removed, and the cause of failure may not be sufficiently preserved on site.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fire detector for a tunnel in which a fire detector can be easily replaced and a waterproof treatment can be easily and reliably performed.

  To achieve this object, the present invention is configured as follows. The present invention provides a mounting part having a threaded hole projecting from a plurality of locations around a detector body, and a stepped-down screw hole provided around the cover of the detector body toward the detector body side. In a fire detector for tunnels in which the screw head is located below the detector surface with the mounting screw being screwed into the mounting part through the mounting screw, the screw head is attached to the tightening part provided on the cover. A protrusion is formed at a position that hides both sides of the portion.

  In this way, the projections that protrude at positions that hide both sides of the screw head are formed on the tightening part provided on the cover, so that the screw is loosened to some extent with a hexagon wrench to look inside the detector body at the site, etc. Even if you try to remove the screw by hand, it will be hindered by the protruding protrusion that hides the screw head, making it difficult to turn, and will give up removing the cover. This ensures that the fire detector is preserved on site when a failure occurs, so that the cause of the failure can be properly investigated.

  Further, the present invention is mounted in a storage box installed in a tunnel, and stores each of a drawing-in signal line drawn in from the outside, a drawing-out signal line drawn out to the outside, and a detector signal line drawn from the detector body. A fire detector for tunnels that is crimped and connected in a box. The detector body has a receptacle attached to the detector body (connector fixed side) and a plug attached to a detector signal line that is detachable from the receptacle. (A connector detachable side).

  Since the waterproof connector is directly attached to the detector body in this manner, the waterproof processing is performed by attaching the receptacle of the waterproof connector to the detector body, and by crimping connection of the incoming signal line, the detector signal line, and the extraction signal line. The waterproof connector side can be waterproofed by a simple technique such as the use of rubber packing, and the number of parts can be reduced.

  Here, the waterproof connector is provided at a position of the detector main body where a distance to the inner side wall of the storage box can be secured. For example, a waterproof connector is provided at the position of the detector body toward the inner side wall corner of the storage box. This increases the open space where the waterproof connector is located when the fire detector is installed inside the storage box, facilitates the attachment and detachment of the waterproof connector, and also allows the signal line from the waterproof connector to be routed inside the box. make it easier.

In the fire detector for a tunnel according to the present invention, an attachment portion having a screw hole protruding from a plurality of locations around the detector main body is provided, and a step is lowered around the cover toward the detector main body side and threaded. A tightening portion having a hole is provided, and a screw head is positioned below the surface of the detector in a state where the mounting portion is screwed into the mounting portion through a mounting screw. With the structure that the head of the screw that attaches the cover to the detector body does not protrude from the detector surface in this way, when installing the fire detector in the box and attaching the storage box cover (front panel) The height of the storage box can be reduced without being hindered by the screw head on the fire detector side.

  According to the present invention, it is difficult to loosen the screw by hand by forming a protruding projection on the tightening portion serving as the mounting portion on the cover side so as to be a position that hides both sides of the screw head, It is possible to ensure the preservation on site when a fire detector fails and to properly investigate the cause of the failure.

  In addition, by attaching the waterproof connector directly to the detector body, waterproofing can be done in two places: the receptacle mounting part of the waterproof connector to the detector body and the crimp connection part of each signal line. Technology, and the number of parts can be reduced.

In addition, as a structure of the attachment part of the detector body and the cover, a fastening part provided around the cover is hung to the detector body side to form a stepped part with no screw head on the top of the fastening part. When attaching the detector to the storage box and attaching the box cover (front panel), the box cover can be attached without disturbing the screw head on the fire detector side, and as a result, the height of the storage box can be reduced. it can.

  FIG. 1 is a front view of a fire detector for a tunnel according to the present invention in a box mounted state. The storage box 1 is installed on a tunnel wall surface, a ceiling, or the like. The fire detector 2 of the present invention is mounted inside the storage box 1 with the front panel 1a removed, and the front panel 1a is mounted after mounting. By doing so, only the front portion of the fire detector 2 projects from the front panel 1a.

  The fire detector 2 is provided with light receiving windows 3a and 3b on inclined surfaces divided into two portions on the left and right, respectively, and a pyroelectric element having sensitivity in a predetermined wavelength band installed inside the light receiving windows 3a and 3b. It tries to detect fire. A test light source housing 4 is provided above the light receiving windows 3a and 3b so as to protrude.

  In the internal mounting structure in which the front panel 1 a of the storage box 1 is removed in FIG. 2, a fire detector is fixed in the box body 1 b of the storage box 1 by screwing the mounting pieces 15. To the fire detector 2 installed in the storage box 1, a signal line 7 for drawing in from the disaster prevention receiver is drawn in, and a signal line 8 for drawing out for the next fire detector is drawn out. The detector signal line 6 drawn from 2 is routed. In the fire detector 2 of the present invention, the detector signal line 6 is connected to the detector body by the waterproof connector 5.

  The waterproof connector 5 includes a receptacle 17 and a plug 18 as shown in FIG. The receptacle 17 is mounted on the detector main body side and has a female contact 19, and when mounted on the detector main body, the packing 20 is interposed between the receptacle 17 and the waterproof processing. On the other hand, the plug 18 has a male contact 21, and when the plug 18 is connected to the receptacle 17, the male contact 21 is fitted and electrically connected to the female contact 19.

  The waterproof connector 5 has a waterproof structure in the receptacle 17 and the plug 18 itself, and has an airtightness when the plug 18 is connected to the receptacle 17 and an airtightness when the signal line cable is connected and fixed to the plug 18 side. Both are reserved.

  Referring to FIG. 2 again, the waterproof connector 5 for connecting the detector signal line 6 to the detector main body of the fire detector 2 is provided in this embodiment from the fire detector 2 to the inner side wall of the box main body 1b. The waterproof connector 5 is provided at a position in the direction toward the lower right corner of the box body 1b as a position where the distance can be maximized. By providing the waterproof connector 5 at a position where the distance from the inner side wall of the box body 1b can be sufficiently secured, the work of attaching and detaching the waterproof connector 5 to and from the fire detector 2 becomes easy. The detector signal line 6 can be easily routed from the protruding portion of the connector.

  Each signal line of the drawing signal line 7, the drawing signal line 8 drawn into the box body 1b, and the signal line 6 for the detector connected to the fire detector 2 by the waterproof connector 5 is connected to the crimp connection portion 9. Connected. As shown in FIG. 4, the connection of the signal lines in the crimping connection portion 9 is, assuming that one of the signal lines is 6a, 7a, 8a, the tip of the three lines 6a, 7a, 8a. After the coating is removed, the core wire 10 is taken out and twisted, then soldered up, and the twisted portion of the core wire 10 is crimped and connected by the crimping unit 11.

  The crimping unit 11 is provided with a crimping fitting 11b at the entrance of a cap-shaped sleeve 11a formed of insulating plastic. The sleeve 11a is filled with an insulating agent such as silicone oil, and the sleeve 11a is The crimping fitting 11b is crushed with a crimping tool in a state where the twisted portion is inserted, and the connection is fixed.

  A set of three crimp-connected signal lines is combined into one as shown in a crimp connection part 9 in FIG. 2, and a waterproof bag 30 is covered with, for example, a plastic bag, and a binder wire is wound thereon and fixed. are doing.

  FIG. 5 is a sectional view of the internal structure of the tunnel fire detector 2 according to the present invention. The fire detector 2 of the present invention includes a cover 2a and a main body 2b, and has a mold cover 22 inside. The receptacle 17 of the waterproof connector 5 is mounted on the main body 2b via a packing 20. A plug 18 to which the detector signal line 8 is attached is detachably provided to the receptacle 17.

  The signal line 24 connected behind the receptacle 17 is connected to a lightning arrester 23 attached to the lower part of the mold cover 22. A main circuit board 26 is disposed above the mold cover 22, and a sensor unit is disposed on the main circuit board 26 in a diagonally right and left direction. The sensor unit includes a first pyroelectric element 27 and a second pyroelectric element. 28 are provided. The first pyroelectric element 27 and the second pyroelectric element 28 monitor a fire in the left and right direction along the wall surface in the tunnel through the light receiving windows 3a and 3b of the cover 2a. The lightning arrester board 23 and the main circuit board 26 are connected by a connector 25.

  In this embodiment, the first pyroelectric element 27 and the second pyroelectric element 28 monitor a fire by a so-called two-wavelength method. The first pyroelectric element 27 has an optical filter characteristic of transmitting narrow-band light having a center wavelength of about 4.5 μm, which is radiated by CO2 resonance generated during flaming combustion, and receives light from the burning flame. . On the other hand, the second pyroelectric element 28 is provided with an optical filter having a wavelength band of approximately 5.0 to 7.0 μm, and receives light in the band of 5.0 to 7.0 μm.

  By using the first pyroelectric element 27 and the second pyroelectric element 28 having the two optical filter characteristics having different optical wavelength bands, sunlight as a noise light against a fire flame and a vehicle (300 ° C low-frequency radiation source) and radiation by the human body can be monitored separately. That is, with respect to the flame due to a fire, the detection output in the narrow band of 4.5 μm by the first pyroelectric element 27 is strongly obtained, and the output in the 5.0 to 7.0 μm band by the second pyroelectric element 28 is extremely low. On the other hand, when sunlight shines as noise light, both the 4.5 μm narrow band of the first pyroelectric element 27 and the 5.0-7.0 μm band of the second pyroelectric element 28 obtain strong light receiving outputs. Can be

  As for the vehicle, both the 4.5 μm narrow band of the first pyroelectric element 27 and the 5.0-7.0 μm band of the second pyroelectric element 28 are substantially similar to sunlight due to the heat current generated by the heating of the engine. A strong light receiving output is obtained. Further, regarding the human body, the light receiving output of the first pyroelectric element 27 in the narrow band of 4.5 μm is weak, and the light receiving output of the second pyroelectric element 28 in the band of 5.0 to 7.0 μm is strong.

  Accordingly, based on the relative ratio of the received light output of the two first pyroelectric elements 27 and the second pyroelectric element 28, the received light output by the flame is accurately detected with respect to the received light output by the sunlight, the vehicle, and the human body, thereby causing a fire. Can be monitored.

  Further, a test light source window 29 is provided corresponding to the light receiving windows 3a and 3b in the test light source housing portion 4 provided so as to protrude above the cover 2a. When the test light source emits light through the test light source window 29, test light is incident on the internal first and second pyroelectric elements 27 and 28 from the light receiving windows 3a and 3b, and a test light receiving output is obtained. As a result, it is possible to detect dirt on the light receiving windows 3a and 3b of the detector and perform sensitivity compensation or failure confirmation.

  FIG. 6 is a front view of the tunnel fire detector 2 of the present invention. FIG. 7 is a side view, and FIG. 8 is a rear view.

  In the front view of the fire detector 2 of FIG. 6, the fastening portions 13 are formed at three places around the cover 2a in a state of protruding outside, and correspondingly, as shown in FIG. A mounting portion 12 is also formed on the 2b side in the same manner, divided into three places and projected to the periphery. A screw hole 12a is formed in each of the mounting portions 12 of the main body 2b.

  On the other hand, a screw hole is formed in the tightening portion 13 on the cover 2a side in FIG. 6, and a screw 14 is passed through the screw hole via a spring washer 32 and screwed into the screw hole 12a in the mounting portion 12 in FIG. Thus, the cover 2a can be tightened and fixed to the main body 2b. As the screw 14 used for attaching the cover 2a, a screw having a hexagonal hole in a cylindrical screw head is used, and the attachment and detachment of the screw 14 is performed using a hexagon wrench.

  Further, the fastening portion 13 shown in FIG. 6 is provided with a pair of convex portions 16 that protrude so as to cover both sides of the head of the screw 14 in a state where the cover 2a is fastened and fixed to the main body 2b by the screw 14.

  FIG. 9 is an exploded view of the cover 2a and the main body 2b in the fire detector for a tunnel according to the present invention. First, on the side of the main body 2b, a mounting portion 12 is provided so as to protrude around the main body 2b, and a screw hole 12a is opened in an upper portion of the mounting portion 12. On the other hand, on the cover 2a side, a fastening portion 13 is provided to protrude outward from the periphery of the cover, and a through hole 13a is formed in the fastening portion 13.

  FIG. 10 shows the cover-side tightening portion and the main-body-side mounting portion of FIG. Here, the fastening portion 13 of the cover 2a projects outward from the front of the cover and is lowered to the body 2b side at the same time, and a through hole 13a is opened in the upper part of the lowered fastening portion 13.

  For this reason, a cutout portion is formed between the opening of the through hole 13a of the tightening portion 13 and the surface of the cover 2a so that the head 14a of the screw 14 can be stored so as not to protrude from the surface. . Further, a pair of protrusions 16 project from the side surface of the cover 2a on both sides of the opening of the through hole 13a of the tightening portion 13, and the head 14a of the screw 14 that has passed through the through hole 13a of the tightening portion 13 is manually held. The protrusion 16 has a function of obstructing the rotation when it is attempted to rotate.

  By forming the tightening portion 13 of the cover 2a so as to be lowered toward the main body 2b, the screw 14 positioned above the tightening portion 13 in the state where the cover 2a and the main body 2b are mounted and fixed by the screw 14 shown in FIG. Is located at a position lower than the surface on the cover 2a side, and does not jump out to the cover surface side.

  With the structure in which the head of the screw 14 does not protrude from the cover surface, the fire detector 2 is mounted in the box body 1b as shown in FIG. 2 and the front panel 1a is mounted thereon as shown in FIG. The back surface of 1a is in close contact with the flat portion around the cover 2a, and only the portion provided with the central light receiving windows 3a and 3b protrudes to the front surface of the front panel 1a. At this time, the head of the screw 14 does not protrude. The front panel 1a can be attached in close contact with the cover surface of the fire detector 2.

  Further, in the tunnel fire detector according to the present invention, there is a possibility that the fire detector may be damaged due to a surge due to, for example, a lightning strike. In such a case, the front panel 1a as shown in FIG. If the screw 14 is loosened in this state, the cover 2a can be removed to inspect the inside.

  However, the fire detector for a tunnel of the present invention originally has a sealed structure, and the waterproof connector 5 shown in FIG. 2 is replaced so that the fire detector itself is replaced even in the event of a failure. Has a structure that is easy to replace with. Therefore, it is not usually planned to remove the cover 2a at the site when a failure occurs and to inspect the inside. However, depending on the situation, the inside may be inspected with the cover removed, and the cause of failure may not be sufficiently preserved on site.

  Therefore, according to the present invention, as shown in FIG. 10, even if the protrusion 16 projects from the tightening portion 13 on the cover 2a side and the head of the screw 14 is loosened with a hexagon wrench, the screw head is The protrusion 16 prevents the cover 2a from being removed at the site, and as a result, preservation of the site in the event of a failure is assured as much as possible.

  Further, the mounting position of the waterproof connector 5 in the fire detector of the present invention is, for example, as shown in the front view of FIG. 6, the mounting position of the cover 2a with respect to the main body 2b, that is, the three positions of the fastening portion 13 to which the screw 14 is mounted. , The waterproof connector 5 is arranged at a position not out of the way.

  That is, in the event that the position of the waterproof connector 5 is overlapped with the mounting position by the three fastening portions 13, the waterproof connector 5 is provided by the fastening portion 13 provided at the mounting position or the mounting portion 12 on the main body side. However, according to the present invention, the waterproof connector 5 is provided outside the mounting position so that the waterproof connector 5 can be easily attached to and detached from the fire detector 2.

  Also, if the mounting position of the mounting portion 12 and the waterproof connector 5 are overlapped, the main body 2b becomes thicker in consideration of the respective spaces and design strength, but the main body 2b is made thinner by displacing the respective arrangements. Can be.

  Note that FIG. 7 shows a state of a mounting hole 5a for mounting the waterproof connector 5 on the main body 2b side.

  FIG. 11 shows another embodiment of the tunnel fire detector according to the present invention. In the above embodiment, for example, as shown in FIG. 6, the mounting positions of the main body 2b and the cover 2a are provided at three places around. However, the embodiment of FIG. 11 is characterized in that it is provided at four places around.

  That is, the tightening portions 13 are provided at four positions, up, down, left, and right of the cover 2a. A pair of protrusions 16 are provided at each of the tightening portions 13, and the screws 14 are attached to the lower portion of the main body 2b located at the lower portion. It is screwed into the screw hole 12b of the mounting portion 12 and fixedly fastened.

  The waterproof connector 5 is mounted at a position deviating from the mounting portion with respect to such four mounting portions, thereby avoiding the inconvenience of attaching and detaching the waterproof connector 5 due to the overlapping position with the mounting portion. are doing. Of course, in the embodiment of FIGS. 6 and 1, the position of the waterproof connector 5 avoids the mounting position of the cover 2a and the main body 2b, and at the same time, when the waterproof connector 5 is stored in the storage box 1 as shown in FIG. Needless to say, it is provided at a position, for example, toward the internal corner where a sufficient distance to the side wall can be secured.

  FIG. 12 shows another embodiment of the fire detector for a tunnel according to the present invention, in which a fire detector 31 having the same structure as that shown in FIG. In this fire detector 31 as well, a waterproof connector 5 is provided on the right side below the detector, and a signal line 6 for the detector is detachably provided to the fire detector 31 by the waterproof connector 5.

  As the waterproof connector 5, a receptacle 17 and a plug 18 having a waterproof structure shown in FIG. 3 are used, and the receptacle 17 is fixed to the fire detector 31 via a packing 20, and the plug 18 is connected to the detector signal line 6. Connect to

  When the fire detector 31 provided with such a waterproof connector 5 is attached to the storage box 1, the signal lines 7 for drawing in and the signal lines 8 for drawing out are drawn into the storage box 1, and are drawn in the box. The leading end of the detector signal line 6 connected to the fire detector 31 by the signal line 7, the lead-out signal line 8, and the waterproof connector 5 is pulled out, and each corresponding signal line is made one by soldering as shown in FIG. Are connected to each other by using a crimping unit, which are collectively formed as a crimping connection portion 9, put in a waterproof bag 30 for waterproofing, and bound by a binder wire.

  In the embodiment of FIG. 12 as well, the waterproof treatment is performed by directly attaching the waterproof connector 5 to the detector main body, so that the waterproof mounting of the receptacle of the waterproof connector 5 to the detector main body and the crimp connection portion 9 of each signal line are performed. Only two locations are required, and the connection of the waterproof connector 5 can be performed by a simple technique of using rubber packing for the receptacle, and the number of parts can be reduced.

It should be noted that the present invention is not limited to the above embodiment, but includes appropriate modifications that do not impair the objects and advantages thereof. Further, the present invention is not limited by the numerical values shown in the above embodiments.

Front view of a fire detector for a tunnel according to the present invention in a box storage state. Explanatory drawing of the mounting structure inside the box with the front panel removed in FIG. Explanatory drawing of the waterproof connector used in the present invention Explanatory drawing of crimp connection of signal lines in the box of FIG. Sectional view of the internal structure of a fire detector for a tunnel according to the present invention. Front view of a fire detector according to the present invention Side view of a fire detector according to the present invention Rear view of a fire detector according to the present invention Exploded view of cover and main body of fire detector according to the present invention Explanatory drawing of the main body mounting part and cover tightening part of FIG. Explanatory drawing of another embodiment of the present invention in which the mounting positions of the cover and the main body are four places. Explanatory drawing showing another embodiment of the present invention for different detector structures Illustration of a conventional tunnel fire detector that only performs signal wire crimping connection Illustration of a conventional fire detector for tunnels using a connector

Explanation of reference numerals

1: Storage box 1a: Front cover 1b: Box body 2, 31: Fire detector 2a: Cover 2b: Detector body 3a, 3b: Light receiving window 4: Test light source housing 5: Waterproof connector 6: Detector signal line 7: Signal line for pull-in 8: Signal line for pull-out 9: Crimp connection portion 10: Core wire 11: Crimp unit 11a: Sleeve 11b: Crimp fitting 12: Mounting portion 12a: Screw hole 13: Tightening portion 13a: Through hole 14: Screw 15: Mounting piece 16: Protrusion 17: Receptacle 18: Plug 19: Female contact 20: Packing 21: Male contact 22: Mold cover 23: Lightning arrester board 24: Signal line 25: Connector 26: Main circuit board 27: First Pyroelectric element (with 4.5μm narrow band filter)
28: 2nd pyroelectric element (with 5-7 μm wide band filter)
29: Window for test light source 30: Waterproof bag

Claims (1)

At the plurality of locations around the detector main body, mounting portions having screw holes are provided so as to protrude, and around the cover of the detector main body, a fastening portion provided with a screw through hole is provided which is stepped down to the detector main body side. In a fire detector for a tunnel in which the screw head is positioned below the detector surface in a state where the screw head is screwed and fixed to the mounting part through the mounting screw through the tightening part,
A fire detector for a tunnel, wherein a projection is formed on a fastening portion provided on the cover so as to protrude at a position where both sides of a screw head are hidden.

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