JP2011128866A - Photoelectric smoke sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric smoke sensor that reduces false alarms due to large particles such as steam. <P>SOLUTION: The photoelectric smoke sensor 1 includes a smoke detection space 27, a light trap 25, a light emitter 21, a light receiver 23 for receiving scattered light, and an optical stand 19 holding the light emitter 21 and the light receiver 23 and blocking direct light traveling from the light emitter 21 to the light receiver 23. The photoelectric smoke sensor includes: a first smoke flow passage forming member for forming a first smoke flow passage 11 extending across an upper part of the smoke detection space 27, a second smoke flow passage forming member forming a second smoke flow passage 13 extending across a lower part of the smoke detection space, and a smoke introduction passage 29 that introduces smoke by communicating the first smoke flow passage 11 with the upper part of the smoke detection space 27, or the second smoke flow passage 13 with the lower part of the smoke detection space. A difference in length is provided between the first smoke flow passage 11 and the second smoke flow passage 13. A differential pressure between the first smoke flow passage 11 and the second smoke flow passage 13 caused by the difference in length between the flow passages is used to introduce smoke into the smoke detection space 27 via the smoke introduction passage 29. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a photoelectric smoke detector that detects smoke by detecting scattered light of light emitted from a light emitter with a light receiver.

The photoelectric smoke detector includes a labyrinth structure that allows inflow of smoke from outside and blocks light from outside to form a smoke detection space, and a light emitter that emits light toward the smoke detection space; And a light receiver for receiving scattered light from the smoke particles in the smoke detection space, and a light blocking body for blocking direct light emitted from the light emitter from reaching the light receiver.
There are two types of smoke detection space and the arrangement of light emitters and light receivers.
One of them is to arrange a light emitter and a light receiver in the same plane as the smoke detection space, and to emit and receive light in the horizontal direction. Among these types, there is no need to bend the lead terminal of the light emitting element using the side light emitting type light emitting element, and the process of damaging the light emitting element by bending the lead terminal is not required, and it is easy to install as designed. Proposed. (See Patent Document 1)
In the other type, a light emitter and a light receiver are disposed above the smoke detection space and light is emitted obliquely downward to receive light (see Patent Documents 2 to 6).

JP-A-06-111156 Japanese Utility Model Publication No. 01-111394 Japanese Patent Laid-Open No. 03-111997 Japanese Patent Laid-Open No. 03-296896 JP 2003-208674 A JP 2004-220155 A

In any type, smoke flows from the surroundings of the labyrinth structure into the smoke detection space, so large particles such as steam are also introduced into the smoke detection space as they are. There was a problem that it was likely to occur.
In addition, as a problem specific to the one using the side light emitting type light emitting element (see Patent Document 1), the light emitting element is exposed in the smoke detecting section, and therefore it is easily contaminated. In addition, since the optical system (light emitter, light receiver, light shielding plate, etc.) needs to be placed in the same horizontal space as the labyrinth structure, the internal structure of the sensor maintains aerodynamic symmetry due to the presence of these optical systems. Therefore, there is also a problem that it has a direction to the inflow of smoke from the outside.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a photoelectric smoke detector that can reduce false alarms caused by particles having a large particle diameter such as steam.
It is another object of the present invention to provide a photoelectric smoke detector that uses a side light-emitting light-emitting element so that the light-emitting element and the like are not easily contaminated and has no directivity in response to smoke.

The smoke introduction path to the smoke detection space in the conventional photoelectric smoke detector is formed on the peripheral surface of a substantially cylindrical labyrinth structure covered with an insect screen. And the smoke which flows along a ceiling surface flows in into smoke detection space directly, without changing the direction of a flow from the surrounding surface of the said labyrinth structure.
The inventor believes that such a smoke introduction path into the smoke detection space allows the inflow of particles having a large particle diameter such as steam as described above, and causes a response to smoke. We thought about renewing the smoke introduction route itself into the smoke space.
And we will study the introduction route of smoke that does not allow the inflow of large particles such as steam and the direction of response to smoke does not occur, and use the flow of airflow (smoke) flowing along the ceiling surface. Considering the formation of an introduction path for introducing smoke from above or below the smoke detection space, such an introduction path does not allow inflow of large particles such as steam, and also has a direction to response to smoke. The knowledge that it does not occur was obtained.
The present invention is based on such knowledge, and specifically comprises the following configuration.

(1) A photoelectric smoke detector according to the present invention is formed by a smoke detection space formed so as to block light from the outside, a light trap that attenuates stray light in the smoke detection space, and the light trap. A light emitter that emits light toward the smoke detection space, a light receiver that receives light scattered from the light emitter by smoke particles in the smoke detection space, and the light emitter provided in the smoke detection space And a photoelectric smoke detector comprising an optical bench that holds the light receiver and blocks direct light from the light emitter toward the light receiver,
A first smoke flow path forming member that forms a first smoke flow path extending across the smoke detection space in the installed state; and a second smoke flow path extending across the smoke detection space in the installed state. A second smoke flow path forming member for forming the first smoke flow path and the upper part of the smoke detection space, or the second smoke flow path and the lower part of the smoke detection space to communicate with each other. And a smoke introduction path to be introduced into the
A difference is provided between the lengths of the first smoke channel and the second smoke channel, and a differential pressure between the first smoke channel and the second smoke channel generated by the difference in the channel length is utilized. Smoke is introduced into the smoke detection space through the smoke introduction path.

(2) Further, in the device described in (1) above, the smoke introduced into the smoke detection space through the smoke introduction path is guided toward a position where the optical axes of the light emitter and the light receiver intersect. It is characterized by comprising a guide member.

(3) Further, in the above (1) or (2), the light emitter has a side light emitting type light emitting element, and the light receiver has a side light receiving type light receiving element. An exhaust path for exhausting smoke introduced into the smoke detection space is provided on the side of the optical trap opposite to the light emission and light reception sides of the light emitter and the light receiver.

(4) Further, in any of the above (1) to (3), the optical trap is composed of a labyrinth structure, and the labyrinth structure has a diameter reduced at least at a lower portion toward a center downward direction. It is characterized by having an inverted cone shape or an inverted truncated cone shape.

The photoelectric smoke detector according to the present invention includes a first smoke flow path forming member that forms a first smoke flow path extending across the smoke detection space in the installed state, and the smoke detection space in the installed state. A second smoke flow path forming member that forms a second smoke flow path extending across the lower side, the first smoke flow path and the upper part of the smoke detection space, or the second smoke flow path and the smoke detection space. A smoke introduction path for introducing smoke by communicating the lower part,
A difference is provided between the lengths of the first smoke channel and the second smoke channel, and a differential pressure between the first smoke channel and the second smoke channel generated by the difference in the length of the channel is used. Since smoke is introduced into the smoke detection space via the smoke introduction path, particles having a large particle diameter such as steam flowing in the first smoke flow path or the second smoke flow path have a large mass, and thus inertia. The force is large, the route is changed and the smoke introduction passage cannot be entered, and only smoke particles having a small particle diameter are introduced into the smoke introduction passage, thereby preventing false reports due to steam or the like.
In addition, since the smoke inlets in the first smoke channel and the second smoke channel can be provided over the entire circumference of the photoelectric smoke sensor, the direction of response to smoke can be eliminated.

It is explanatory drawing of the internal structure of the photoelectric smoke detector which concerns on one embodiment of this invention. It is arrow AA sectional drawing in FIG. It is explanatory drawing of the optical trap installed in the photoelectric smoke detector which concerns on one embodiment of this invention. It is operation | movement explanatory drawing of the photoelectric smoke detector which concerns on one embodiment of this invention. It is explanatory drawing of the external appearance of the photoelectric smoke sensor which concerns on one embodiment of this invention, Fig.5 (a) is a front view, FIG.5 (b) is a bottom view. It is explanatory drawing of the internal structure of the photoelectric smoke detector which concerns on Embodiment 2 of this invention. It is explanatory drawing of the external appearance of the photoelectric smoke detector which concerns on Embodiment 2 of this invention, Fig.7 (a) is a front view, FIG.7 (b) is a bottom view. It is explanatory drawing of the internal structure of the photoelectric smoke detector which concerns on Embodiment 3 of this invention. It is arrow BB sectional drawing in FIG. It is explanatory drawing of the external appearance of the photoelectric smoke detector which concerns on Embodiment 3 of this invention, Fig.10 (a) is a front view, FIG.10 (b) is a bottom view. It is explanatory drawing of the internal structure of the photoelectric smoke detector which concerns on Embodiment 4 of this invention. It is arrow AA 'sectional drawing in FIG. It is arrow BB 'sectional drawing in FIG. It is explanatory drawing of the internal structure of the photoelectric smoke detector which concerns on Embodiment 5 of this invention. It is arrow AA 'sectional drawing in FIG. It is arrow BB 'sectional drawing in FIG.

[Embodiment 1]
A photoelectric smoke detector 1 according to the present embodiment will be described with reference to FIGS.
The photoelectric smoke detector 1 according to the present embodiment includes a main body 2 and a circular base 3 which is attached to a ceiling or the like and holds the main body 2 detachably at a lower portion thereof. The main body 2 includes a protective cover 5 and a wall body 7 disposed on the upper portion of the protective cover 5.
As shown in FIG. 2, the wall body 7 has a plurality of labyrinth members 7 a having an axial cross section, for example, substantially J-shaped (J-shaped having a horizontal bar at the head) arranged on the same circumference at regular intervals. Thus, the labyrinth structure is formed in a substantially cylindrical shape. An insect net 9 is installed on the outer periphery of the wall body 7.
By constructing the wall body 7 with a labyrinth structure, it is possible to allow smoke to flow into the wall body 7 and to prevent external light from entering.
A region surrounded by the wall body 7, the protective cover upper surface 5 a, and the main body upper surface member 10 is a first smoke flow path 11 for smoke flowing from the outside of the wall body 7. Therefore, in this Embodiment, the wall body 7, the protective cover upper surface 5a, and the main body upper surface member 10 comprise a 1st smoke flow path formation member.

  As shown in FIG. 5, the protective cover 5 is formed in a spherical surface convex downward. A smoke exhaust hole 12 for exhausting smoke from a smoke detection space 27 described later is formed at the top (lowermost part) of the spherical surface. As will be described later, the smoke flowing along the ceiling surface flows along the surface of the protective cover 5, so that the lower surface of the protective cover 5 becomes the second smoke flow path 13 and the protective cover 5 forms the second smoke flow path. It becomes a member.

The main body 2 includes a circuit board 17 installed above the protective cover 5, an optical table 19 installed on the lower surface side of the circuit board 17, a light emitter 21 and a light receiver 23 installed on the optical table 19, An optical trap 25 is provided so as to surround the optical bench 19, and an internal space surrounded by the optical trap 25 is a smoke detection space 27.
A smoke introduction passage 29 is provided so as to penetrate the upper surface of the protective cover 5, the circuit board 17, and the optical bench 19, and the first smoke passage 11 and the smoke detection space 27 communicate with each other through the smoke introduction passage 29. is doing. The space surrounded by the protective cover 5 including the smoke detection space 27 includes a negative pressure chamber 30 that becomes a negative pressure according to Bernoulli's theorem, which will be described later, when an airflow flows through the first smoke channel 11 and the second smoke channel 13. It has become.
Hereinafter, main components constituting the main body 2 will be described in more detail.

<Optical stand>
The optical bench 19 includes a light emitter housing portion 19 a for housing the light emitter 21, a light receiver housing portion 19 b for housing the light receiver 23, and a portion of the smoke introduction path 29 disposed at the center of the optical bench 19. The light shielding part 19c which comprises is provided. The light shielding portion 19c is formed in a slit shape by two opposing plate-like members, constitutes a part of the smoke introduction path 29, and guides the smoke toward the intersection of the optical axes of the light emitter 21 and the light receiver 23. It also functions as a light guide member that prevents direct light from the light emitter 21 from entering the light receiver 23.
As shown in FIG. 1, the light emitter housing portion 19 a houses the light emitter 21 obliquely downward so that light emitted from the light emitter 21 is emitted toward the smoke detection space 27. . Similarly to the light emitter housing portion 19a, the light receiver housing portion 19b houses the light receiver 23 obliquely downward as shown in FIG. 1, and can receive scattered light incident from obliquely below. I have to.
As described above, in the present embodiment, the light emitter 21 and the light receiver 23 are arranged obliquely downward, so that the light shielding portion 19c does not extend to the intersection of the optical axes of the light emitter 21 and the light receiver 23. The introduced smoke is discharged downward toward the intersection and functions as a guide member.

<Optical trap>
The optical trap 25 has a function of attenuating light emitted from the light emitter 21 and may have any form as long as it has such a function.
As one form of the optical trap 25 having such a function, FIG. 1 shows an overall shape of the optical trap 25 which is formed in a substantially inverted conical shape whose diameter decreases toward the lower center.

In addition, as shown in FIG. 3, the optical trap 25 inclines a plurality of labyrinth members 31 (see FIG. 3) whose axial cross section is substantially J-shaped (J-shaped having a horizontal bar at the head), for example. The labyrinth structure may be formed in a substantially inverted conical shape by arranging them on the same circumference at regular intervals.
As shown in FIG. 3, the inner peripheral surface in the case of the labyrinth structure has alternating surfaces formed by portions corresponding to the horizontal bars of the J-shaped head (hereinafter referred to as horizontal bar portions 31a). It is supposed to overlap. The horizontal bar portion 31a has an inclined surface, and dust or the like entering the smoke detecting space 27 slides down the inclined surface and falls downward from the gaps between the labyrinth members 31.

An exhaust port 33 is formed at the lower end of the optical trap 25 so that the smoke introduced into the smoke detection space 27 can be exhausted. However, when the labyrinth structure as shown in FIG. 3 is used as the optical trap 25, a gap is formed between the labyrinth members 31, and the gap functions as the exhaust port 33. 33 need not be provided. However, since the exhaust port 33 functions as a discharge port for dust or the like that has entered the smoke detection space 27, it is preferably provided in that sense.
The smoke introduced into the smoke detection space 27 is discharged from the smoke exhaust hole 12 of the protective cover 5 to the second smoke flow path 13 side through the exhaust port 33 or the gap between the labyrinth members 31. Therefore, the path from the exhaust port 33 or the gap between the labyrinth members 31 to the smoke exhaust hole 12 is the smoke exhaust path.

  Between the smoke exhaust hole 12 formed in the protective cover 5 and the light trap 25, a light blocking body 35 for blocking light incident from the smoke exhaust hole 12 is installed.

<Description of operation>
In the photoelectric smoke sensor 1 configured as described above, smoke generated by a fire flows along a ceiling surface (not shown) as shown by the broken arrow in FIG. And while flowing in into the 1st smoke flow path 11 via the insect net 9, it flows along the 2nd smoke flow path 13 along the lower surface of the protective cover 5, and merges again. At this time, since the length of the second smoke flow path 13 along the lower surface of the protective cover 5 is longer than the length of the first smoke flow path 11, the flow velocity of the smoke flowing through the second smoke flow path 13 is the first smoke flow. It becomes faster than the flow velocity flowing through the path 11.
Due to this difference in flow velocity, the air pressure in the second smoke channel 13 is lower than the air pressure in the first smoke channel 11 based on Bernoulli's theorem. And since the 1st smoke flow path 11 and the 2nd smoke flow path 13 are connected via the smoke introduction path 29, the smoke detection space 27, and the smoke exhaust hole 12, negative pressure is caused by the difference in the atmospheric pressure. The pressure chamber 30 becomes negative pressure and smoke is introduced from the smoke introduction path 29 into the smoke detection space 27, and the light emitted from the light emitter 21 is scattered by the introduced smoke and incident on the light receiver 23 to be detected. .
The smoke introduced into the smoke detection space 27 is discharged to the smoke exhaust hole 12 through the exhaust port 33 or the gap between the labyrinth members 31.

As described above, according to the present embodiment, smoke is introduced into the smoke detection space 27 by the differential pressure between the first smoke channel 11 and the second smoke channel 13 generated when smoke flows, and light emission Irradiates light from the vessel 21 and sends the smoke directly to the area where the scattered light from the smoke particles is received, so that smoke can be stably introduced to the required location, the light receiving output is stable, and smoke detection is ensured. Can be done.
Further, even if steam or the like flows into the first smoke channel 11, particles having a large particle diameter such as steam that flows in have a large inertial force due to their large mass, and change the course and enter the smoke introduction channel 29. However, since only smoke particles having a small particle diameter flow into the smoke introduction passage 29 and pass through to the opposite side to the inflow side of the first smoke passage 11, it is possible to reduce misinformation due to steam or the like.

  In the present embodiment, since a substantially inverted conical labyrinth structure is used as the optical trap 25, the light irradiated from the light emitter 21 is irradiated to the optical trap 25 extending toward the lower center and attenuated. The And since the labyrinth member 31 which comprises the optical trap 25 is inclinedly arranged, dust etc. do not accumulate indefinitely, Therefore It can prevent generating noise light and generating misinformation.

In the above embodiment, an example using the labyrinth structure having a substantially inverted truncated cone shape whose diameter is reduced toward the lower center as an example of the optical trap 25 is shown. The present invention is not limited, and other forms may be used as long as stray light in the smoke detection space 27 is attenuated.
In the above example, the labyrinth member 31 has a substantially J-shaped cross section. However, the shape of the labyrinth member 31 is not limited to this, and for example, the cross-section has a substantially letter-shaped or substantially Z-shaped section. It may be.

  In addition, although not shown in figure, the smoke exhaust hole 12 may be provided with the insect net which prevents that a foreign material penetrate | invades. Of course, it is sufficient if there is a gap between the smoke exhaust hole 12 and the light shielding body 35 that allows air to flow only enough to convey the negative pressure according to Bernoulli's theorem. Insect screens are no longer necessary if they are not able to penetrate.

[Embodiment 2]
A second embodiment of the present invention will be described with reference to FIGS. 6 and 7, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
The photoelectric smoke detector 36 according to the second embodiment is different from the first embodiment in the shape of the protective cover 38 in the main body 37. As shown in FIGS. 6 and 7, the protective cover 38 of the present embodiment has an inverted truncated cone shape on the side surface.

  Thus, even if the side surface shape of the protective cover 38 is formed in an inverted truncated cone shape, the second smoke flow path 13 along the lower surface of the protective cover 38 is longer than the first smoke flow path 11. Therefore, as described in the first embodiment, based on Bernoulli's theorem, the pressure in the second smoke flow path 13 is lower than the pressure in the first smoke flow path 11, and the smoke is detected from the smoke introduction path 29. 27, the same operational effects as in the first embodiment can be achieved.

[Embodiment 3]
A photoelectric smoke detector 39 according to Embodiment 3 of the present invention will be described with reference to FIGS. 8 to 10, the same parts as those in Embodiment 1 are denoted by the same reference numerals, and the description thereof is omitted.
The third embodiment is different from the first embodiment in that the light emitter 41 emits light to the side and the light receiver 43 is a side view type that receives light from the side. Then, the light shielding part 19c is changed to a light shielding column 19d having a groove part 190d as a member for guiding smoke introduced from the smoke introduction path 29 in accordance with the side view type of the light emitting device 41 and the light receiving device 43, and further detection. The shape of the light trap 45 forming the smoke space 27 is changed. Further, as the shape of the light trap 45 is further changed, the shape of the protective cover 47 in the main body 46 is also changed.
Hereinafter, the changes will be described in detail.

  Since the light emitting device 41 and the light receiving device 43 are of the side view type, it is not necessary to bend the light emitting element of the light emitting device 41 and the lead terminal of the light receiving device of the light receiving device 43 at the time of assembly. Can be installed on the street. As a result, it is possible to obtain a sensor having a long service life and good smoke detection sensitivity.

  Since the light emitter 41 and the light receiver 43 are of the side view type, the light emitter 41 emits light in the lateral direction, and the light receiver 43 receives the light in the lateral direction. For this reason, since the light shielding portion 19c shown in the first and second embodiments has a short downward length, the light receiver 43 receives direct light from the light emitter 41. Therefore, in order to prevent direct light reception, the light shielding column 19d is extended downward from the case of the light shielding portion 19c of the first and second embodiments. Further, the groove 190 d of the light shielding column 19 d is provided on the intersection side of the optical axis of the light emitter 41 and the light receiver 43, and thereby smoke introduced from the smoke introduction path 29 is changed to the optical axis of the light emitter 41 and the light receiver 43. It is comprised so that it may guide to a horizontal direction toward the intersection point side.

Further, since the light emitter 41 and the light receiver 43 are side view type, the structure for attenuating the stray light in the light trap 45 extends over the entire circumference of the smoke detection space 27 as shown in FIG. Rather, it is provided in the light emitting side of the light emitting device 41 and the light receiving device 43 and the region facing the light receiving side. As a result, the smoke exhaust path becomes the side where the structure is formed, and the smoke introduced into the smoke detection space 27 flows in a direction away from the light emitter 41 and the light receiver 43. Therefore, the light emitter 41 and the light receiver 43 Even in the side view type, it is possible to prevent dirt from adhering to the light emitter 41 and the light receiver 43, and therefore it is possible to prevent false or misreporting due to dirt.
In addition, since the shape of the optical trap 45 is set as described above, the shape of the optical trap 45 can be reduced, and the protective cover 47 for storing the optical trap 45 has a recessed portion on the peripheral surface as shown in FIGS. The shape has.
By making the shape of the protective cover 47 as described above, the volume of the negative pressure chamber 30 is reduced, and the differential pressure generated in the first smoke channel 11 and the second smoke channel 13 can be reflected with high sensitivity.

In the present embodiment configured as described above, smoke generated by a fire flows into the first smoke flow path 11 through the insect net 9 and the wall body 7 as in the first and second embodiments. At the same time, it flows through the second smoke passage 13 along the lower surface of the protective cover 47. Then, smoke is introduced from the smoke introduction passage 29 into the smoke detection space 27 by the differential pressure generated in the first smoke passage 11 and the second smoke passage 13. The smoke introduced into the smoke detection space 27 is guided in the lateral direction by a groove 190d formed in the light shielding column 19d, and the light scattered by the smoke is detected by the light receiver 43.
The smoke introduced into the smoke detection space 27 flows in the direction in which the structure for stray light attenuation in the light trap 45 is formed, that is, in the direction away from the light emitter 41 and the light receiver 43, passes through the gap between the structures, and emits smoke. Guided to hole 12.

As described above, according to the present embodiment, by making the light emitter 41 and the light receiver 43 side-view type, the above-described effect of facilitating the mounting of the light emitting element and the light receiving element can be obtained, and the optical Although the part (such as the optical trap 45) is not symmetrical, it is introduced from the first smoke channel 11 through the smoke inlet formed over the entire upper periphery of the photoelectric smoke detector 39. There is no direction for the introduction of smoke. Therefore, the photoelectric smoke detector 39 according to the present embodiment has no directionality in principle with respect to the introduction of smoke, even though the side-view photoelectric element is used.
Further, since the smoke introduced into the smoke detection space 27 flows away from the light emitter 41 and the light receiver 43 and is discharged from the smoke detection space 27, the light emitter 41 and the light receiver 43 are exposed in the smoke detection space 27. In spite of this, the ratio of dirt adhering to the light emitter 41 and the light receiver 43 is small, making the light emitter 41 and the light receiver 43 difficult to get dirty. There is less information.

  In the present embodiment, the groove-shaped light shielding column 19d is illustrated as a guide member for guiding smoke from the smoke introduction path 29 to a desired position in the smoke detection space 27. However, the base end side of the light shielding column is cylindrical. By making the groove shape only on the tip side, it is possible to achieve an effect that the smoke can be guided to a desired position with a pinpoint.

[Embodiment 4]
A photoelectric smoke detector 50 according to Embodiment 4 of the present invention will be described with reference to FIGS.
The photoelectric smoke detector 50 according to the present embodiment is obtained by partially changing the configuration of the photoelectric smoke detector 39 according to the third embodiment. In FIG. 11 to FIG. Are denoted by the same reference numerals, and the description thereof is omitted.
In the present embodiment, instead of the wall body 7 made of the labyrinth structure in the third embodiment, the plate bodies 53 are radially arranged separated by a predetermined distance, and the insect screen 55 and the light shielding plate are provided on the entrance side of the smoke introduction path 29. 57 is installed.

In the present embodiment, since the plate body 53 is installed instead of the wall body 7 in the third embodiment, the resistance to the inflow of smoke is extremely small, so that the smoke smoothly flows into the first smoke channel 11. It can flow in and has excellent responsiveness.
Further, since the plate bodies 53 are arranged radially, it functions as a guide member that guides the smoke flowing into the plate bodies 53 toward the smoke introduction path 29, and this also has the effect of increasing the responsiveness. Yes.
It is sufficient that there is a gap between the light-shielding plate 57 and the smoke introduction passage 29 so that air can flow only enough to transmit the differential pressure according to Bernoulli's theorem. The insect screen 55 is not necessary if it is set so as to prevent intrusion.

[Embodiment 5]
A photoelectric smoke detector 59 according to Embodiment 5 of the present invention will be described with reference to FIGS.
The photoelectric smoke detector 59 according to the present embodiment is obtained by partially changing the configuration of the photoelectric smoke detector 50 according to the fourth embodiment, and is the same as the fourth embodiment in FIGS. 14 to 16. Are denoted by the same reference numerals, and the description thereof is omitted.
An outline of the structure of the photoelectric smoke sensor 59 of the present embodiment will be described. The photoelectric smoke sensor 59 relates to the structure of the main body 60. The protective cover 47 of the photoelectric smoke sensor 50 and the internal structure thereof according to the fourth embodiment. This corresponds to an object that is turned upside down so that smoke flows in the smoke detection space 27 from the lower part toward the upper part. This will be described in detail below.

  As described above, the protective cover 61 is obtained by turning the protective cover 47 of Embodiment 4 upside down. The lower surface 61c is a flat surface, and the side surface 61b is an inclined surface that is inclined toward the upper surface while being reduced in diameter. 61a is a substantially flat surface. The length of the first smoke passage 11 that crosses the upper surface 61 a of the protective cover 61, that is, the upper portion of the smoke detection space 27 is the length of the second smoke passage 13 that crosses the lower surface 61 c of the protective cover 61, that is, the lower portion of the smoke detection space 27. It is longer than the length. Therefore, when smoke flows through the first smoke channel 11 and the second smoke channel 13, the pressure on the second smoke channel 13 side is lower than that on the first smoke channel 11 side. It flows into the smoke detection space 27 from the smoke channel 13 side and is discharged to the first smoke channel 11 side.

A smoke inlet 63 is formed at the center of the lower surface of the protective cover 61, an insect screen 65 is installed on the inner surface thereof, and a light shielding plate 67 is provided on the inner surface thereof. A smoke introduction path 29 is formed on the inner surface side of the light shielding plate 67 so as to communicate with the smoke detection space 27. A circuit board 17 is installed inside the protective cover 61, an optical bench 19 and an optical trap 45 are installed thereon, a smoke detection space 27 is formed inside the optical trap 45, and an upper surface of the optical trap 45 A light shield 35 is provided.
A smoke exhaust port 69 is formed on the upper surface of the protective cover 61, and an insect screen 71 is installed inside the smoke exhaust port 69.
The protective cover 61 is connected to the main body upper surface member 10 by a plate body 53, and the main body upper surface member 10 and the circuit board 17 are connected by a through electrode 73.

In the photoelectric smoke detector 59 of the present embodiment configured as described above, smoke generated by a fire flows along the ceiling surface, and flows into the first smoke flow path 11 along the side surface and the upper surface of the protective cover 61. While flowing in, it flows along the second smoke flow path 13 along the lower surface of the protective cover 61. At this time, since the length of the first smoke flow path 11 is longer than the length of the second smoke flow path 13, the flow speed of the smoke flowing through the first smoke flow path 11 is faster than the flow speed flowing through the second smoke flow path 13. Become. Therefore, due to the difference in flow velocity, based on Bernoulli's theorem, the pressure in the first smoke flow path 11 is lower than the pressure in the second smoke flow path 13, and the smoke enters the smoke detection space 27 from the smoke introduction path 29. The light emitted from the light emitter 21 by the introduced smoke is scattered and incident on the light receiver 23 to be detected.
The smoke introduced into the smoke detection space 27 passes through the gap of the light trap 45, passes through the smoke exhaust hole 69 through the insect net 71, and is exhausted to the first smoke flow path 11 side.
It should be noted that there is a gap between the light shield 35 and the smoke exhaust port 69 or between the light shield 35 and the protective cover 47 so as to allow air flow to transmit the differential pressure according to Bernoulli's theorem. If this gap is set to be extremely small so that foreign matter intrusion, particularly insects cannot enter, the insect screen 71 is not required.
Similarly, if the gap between the light shielding plate 67 and the smoke inlet 63 or between the light shielding plate 67 and the smoke introduction passage 29 is set to be extremely small so that foreign matter cannot enter, especially insects cannot enter, The net 65 becomes unnecessary.

As described above, in the photoelectric smoke detector 59 of the present embodiment, smoke is introduced from the lower surface side of the protective cover 61 into the smoke detection space 27, so that a fire occurs immediately below the photoelectric smoke detector 59. Thus, even if the air flow containing smoke rises from directly below the photoelectric smoke detector 59, it can be reliably introduced into the smoke detection space 27.
Therefore, the photoelectric smoke detector 59 of the present embodiment has an effect that the smoke can be reliably introduced into the smoke detection space 27 regardless of the direction of the flow of the airflow including smoke.
Further, even if water vapor in the inflowing air comes into contact with the sensor main body 60 and dew condensation occurs, the air flow inside the sensor flows from the smoke inlet 63 to the upper side of the smoke outlet 69, so that the first smoke channel 11 The water droplets generated in the inside of the smoke exhaust port 69 do not enter because it is in the blowing direction, and the water droplets generated on the lower surface 61c of the protective cover on the second smoke flow path side hardly enter the smoke inlet 63 due to gravity. However, it collects in the lower part in the protective cover 61, and neither invades into the smoke detection space 27, and has the effect of preventing false reports due to condensation.
In addition to the above effects, it goes without saying that the same effects as the effects produced by the photoelectric smoke detector 50 of the fourth embodiment can be obtained.

DESCRIPTION OF SYMBOLS 1 Photoelectric smoke detector 2 Main body 3 Base 5 Protective cover 5a Protective cover upper surface 7 Wall 7a Labyrinth member 9 Insect net 10 Main body upper surface member 11 First smoke channel 12 Smoke exhaust hole 13 Second smoke channel 17 Circuit board 19 Optical bench 19a Light emitter housing portion 19b Light receiver housing portion 19c Light shielding portion 19d Light shielding column 21 Light emitter 23 Light receiver 25 Light trap 27 Smoke detection space 29 Smoke introduction path 30 Negative pressure chamber 31 Labyrinth member 31a Horizontal bar portion 33 Exhaust port 35 Light shield 36 Photoelectric smoke detector 37 Main body 38 Protective cover 39 Photoelectric smoke detector 41 Light emitter 43 Light receiver 45 Optical trap 46 Main body 47 Protective cover 190d Groove 50 Photoelectric smoke detector 53 Plate body 55 Insect net 57 Light shield plate 59 Photoelectric smoke detector 60 Main body 61 Protective cover 63 Smoke inlet 65 Insect net 67 Light shielding plate 69 Smoke exhaust 71 Network 73 through electrode

Claims (4)

A smoke detection space formed so as to block light from outside, a light trap that attenuates stray light in the smoke detection space, a light emitter that emits light toward the smoke detection space, and a smoke detection space in the smoke detection space A light receiver that receives scattered light from the light emitter due to smoke particles, and a direct light that is provided in the smoke detection space to hold the light emitter and the light receiver and travel from the light emitter to the light receiver. In a photoelectric smoke detector with an optical bench to block,
A first smoke flow path forming member that forms a first smoke flow path extending across the smoke detection space in the installed state; and a second smoke flow path extending across the smoke detection space in the installed state. A second smoke flow path forming member for forming the first smoke flow path and the upper part of the smoke detection space, or the second smoke flow path and the lower part of the smoke detection space to communicate with each other. And a smoke introduction path to be introduced into the
A difference in length is provided between the first smoke channel and the second smoke channel, and a differential pressure between the first smoke channel and the second smoke channel generated by the difference in the length of the channel is used. A photoelectric smoke detector, wherein smoke is introduced into the smoke detection space through the smoke introduction path.   2. A guide member that guides smoke introduced into the smoke detection space through the smoke introduction path toward a position where an optical axis of the light emitter and the light receiver intersects with each other. The photoelectric smoke detector as described.   The light emitter has a side light emitting type light emitting element, and the light receiver has a side light receiving type light receiving element, and faces the light emitting and light receiving sides of the light emitter and the light receiver in the optical trap. The photoelectric smoke detector according to claim 1, wherein an exhaust passage for exhausting smoke introduced into the smoke detection space is provided on the side.   The optical trap comprises a labyrinth structure, and the labyrinth structure has an inverted conical shape or an inverted frustoconical shape in which at least a lower portion thereof is reduced in diameter toward a lower center direction. 4. The photoelectric smoke detector according to any one of 3 above.