JP5237004B2 - Photoelectric smoke detector - Google Patents

Description

  The present invention includes a housing having a plurality of labyrinth-like wall portions juxtaposed via a gap so as to allow smoke from the outside to flow in and block light from the outside, and to irradiate the inside of the housing with light The present invention relates to a photoelectric smoke detector including a light emitting unit and a light receiving unit that detects scattered light caused by smoke flowing into the housing.

As prior art document information related to this type of photoelectric smoke detector, there is Patent Document 1 shown below. In the photoelectric smoke detector described in Patent Document 1, when smoke enters the housing, the light can be detected by detecting the scattered light formed by the smoke with the light receiving unit.
The angle formed between the axes of the light emitting unit and the light receiving unit is in the range of 120 ° to 140 ° as a value based on the experimental results in which the sensitivity of entering smoke did not decrease and the influence of ambient light was small. Is set to

JP-A-9-231485 (Claim 1, paragraph 0013, FIG. 1, FIG. 4)

  However, in the photoelectric smoke sensor described in Patent Document 1, when fine dust entering from the outside accumulates on the edge of the light shielding wall that blocks direct light from the light emitting portion to the light receiving portion, In the absence of light, scattered light was generated, which could cause false detection.

  Therefore, in view of the drawbacks of the photoelectric smoke detector according to the prior art exemplified above, the object of the present invention is a photoelectric type that has a sufficiently high smoke detection capability and is less prone to erroneous detection due to dust entering from the outside. It is to provide a smoke detector.

The first characteristic configuration of the photoelectric smoke detector according to the present invention is:
A housing having a plurality of labyrinth-like wall portions juxtaposed via a gap so as to allow smoke from outside and block light from outside;
A light emitting unit for irradiating light inside the housing;
A light receiving unit that detects scattered light from smoke flowing into the housing, and
A reflector that reflects the light emitted from the light emitting unit toward a smoke detection region including a crossing point between the light emitting unit and the light receiving unit is disposed to face the light emitting unit. And
In the installation state in which the plane including the axis of the light emitting unit and the axis of the light receiving unit is vertical, the gap adjacent to the upper side of the reflector and the back of the reflector in the radial direction And a dust introduction path that communicates with each other without passing through the reflecting surface of the reflecting plate ,
Between the labyrinth-shaped wall portion located above the reflector and the reflector, a wall body extending in the circumferential direction, and an extension extending radially inward from both circumferential ends of the wall body, A cross section made of a U-shaped deformed wall is provided,
The dust introduction path is formed by two gaps formed above and below the deformation wall portion and an inner peripheral surface of the deformation wall portion .

  In the photoelectric smoke detector according to the first characteristic configuration of the present invention, the axial centers of the light emitting unit and the light receiving unit are configured to form an angle of less than 100 °, so that the light receiving unit is emitted from the light emitting unit. It is sufficiently separated from the light flux of light, and erroneous detection due to the light receiving unit directly detecting the light emitted from the light emitting unit is reduced. On the other hand, when the axes of the light emitting unit and the light receiving unit form an angle of less than 100 °, when the smoke entering the smoke detection region forms scattered light, the light receiving unit has a sufficient light component. Since it does not reach, the sensing ability tends to decrease. However, in the photoelectric smoke detector according to the first characteristic configuration, the reflector disposed opposite to the light emitting unit reflects the light emitted from the light emitting unit toward the smoke detection region. The brightness or light quantity of the scattered light generated by the smoke entering the lamp increases. As a result, although it is a simple method of installing a reflecting plate, it is possible to effectively realize a reduction in sensing ability.

Further, according to this configuration, in the installation state in which the plane including the axis of the light emitting unit and the axis of the light receiving unit is vertical, the gap adjacent to the upper side of the reflector and the back of the reflector And a dust introduction path that connects the gaps that are opposed to each other in the radial direction without passing through the reflection surface of the reflection plate, even when dust or the like enters from the gap adjacent to the upper side of the reflection plate, Since it is possible to move to the space behind the reflector via the dust introduction path, it is difficult for the dust to adhere to or accumulate on the reflecting surface, and thus the reflectance of the reflector is easily maintained over a long period of time.

Another characteristic configuration of the present invention is that the reflecting surface of the reflecting plate is arranged so as to be in a vertical or downward posture.

With this configuration, it is difficult for dust and minute insect carcasses to accumulate on the reflecting surface as compared with a configuration in which the reflecting surface is oriented upward from the vertical. Easy to maintain.

  Another characteristic configuration of the present invention is that the light emitting unit and the reflecting plate are disposed sideways, and the light receiving unit is disposed directly above the smoke detection region.

  In this configuration, the optical axes of the light emitting unit and the light receiving unit, and the optical axes of the reflecting plate and the light receiving unit intersect at about 90 °, so that the detection capability of the scattered light by the light receiving unit is sufficient. In addition, since the light receiving unit is disposed right above the smoke detection region, the light receiving unit suppresses the entry of dust that easily enters the housing from above.

  Another feature of the present invention is that a condensing lens for condensing light from a light source is provided in the light emitting section.

  With this configuration, the light from the light source can be condensed near the smoke detection region, so that a false detection due to the light from the light emitting unit reaching the light receiving unit directly or a light shielding wall is provided. In this case, it is easy to suppress erroneous detection due to scattered light caused by dust accumulated on the edge of the light shielding wall.

  Hereinafter, an embodiment of a photoelectric smoke detector according to the present invention will be described with reference to the drawings. Here, a case will be described in which the present invention is applied to the smoke detector 2 of the fire alarm device 1 which is assumed to be used by being mounted on the most common indoor vertical wall surface in a wall-mounted manner.

  The fire alarm device 1 exemplified here, as shown in FIGS. 1A and 1B, notifies the smoke detection unit 2 that detects smoke, and the detection of smoke by an alarm sound such as voice or buzzer. An alarm speaker unit 3 and an alarm lamp 4 for notifying the detection by lighting or blinking of light by an LED or the like are provided. The smoke detection unit 2 includes a cylindrical housing 21. When the smoke detector 2 detects smoke, the fire alarm 1 determines, for example, whether the smoke concentration is higher or lower than a preset threshold value, and determines that a fire occurs when the smoke concentration exceeds the threshold value. Then, the alarm speaker 3 and the alarm lamp 4 are activated. The activated alarm speaker 3 and alarm lamp 4 can be stopped by operating the alarm stop button 5. On the back of the fire alarm 1, there are provided an attachment part (not shown) for fixing the fire alarm 1 to a wall material, a battery storage part (not shown) for storing a battery for driving the fire alarm 1, etc. is there.

  As shown in FIG. 2, a smoke detection chamber 22 that detects smoke is provided inside the housing 21. The housing 21 is provided with a plurality of bowl-shaped walls 23 so as to surround the smoke detection chamber 22. A large number of these wall-like wall portions 23 are juxtaposed via a gap portion such as a crank shape, so that external light does not enter the smoke sensing chamber 22 and smoke flows from the outside. The labyrinth structure which permits is formed. As shown in FIG. 1B, an insect screen 24 is provided outside the wall portion 23 to prevent erroneous detection due to insects entering the smoke sensing chamber 22.

  Inside the housing 21, there are provided a light emitting unit 25 that irradiates the smoke sensing chamber 22 with light such as near infrared rays, and a light receiving unit 26 that detects scattered light caused by smoke flowing into the smoke sensing chamber 22. The light emitting unit 25 includes a light emitting element 25D such as a light emitting diode as a light source, and a condenser lens 25L disposed in front of the light emitting element 25D. The light receiving unit 26 includes a light receiving element 26D such as a photodiode, and a condenser lens 26L disposed in front of the light receiving element 26D.

  Further, a reflection plate 27 that reflects part of the light emitted from the light emitting unit 25 mainly toward the smoke detection region 22 </ b> A is disposed to face the light emitting unit 25. The reflecting plate 27 is a mirror surface having a high reflectivity by polishing a rectangular resin surface with a No. 2000 compound.

  The light emitting unit 25 is arranged so that the optical axes of the light emitting element 25D and the condenser lens 25L are substantially horizontal. The light receiving unit 26 is disposed in a downward posture on the uppermost part inside the housing 21 so that the optical axes of the light receiving element 26D and the condenser lens 26L are substantially vertical. The optical axes of the light emitting unit 25 and the light receiving unit 26 intersect each other at about 90 ° at the approximate center of the smoke sensing chamber 22. The center of the reflecting plate 27 is disposed on the optical axis of the light emitting unit 25, but its reflecting surface is strictly directed downward (at an angle of 0.5 ° to 5 °) slightly from the horizontal direction. Therefore, the optical axes of the reflecting plate 27 and the light receiving unit 26 intersect slightly below the center of the smoke sensing chamber 22. The smoke detector 2 detects the presence of smoke by detecting scattered light generated when smoke enters the smoke detection area 22A that spreads around these intersections.

  By the way, when used as a wall-hanging type as in the present embodiment, that is, in a state where the plane including the axis of the light emitting unit 25 and the axis of the light receiving unit 26 is substantially along the vertical wall surface of the building, It is easy to enter the inside of the housing 21 from the gap. Therefore, as described above, by providing the light receiving element 26 above, entry of dust into the smoke sensing chamber 22 is suppressed. Further, the light receiving surface of the light receiving element 26 is directed downward to prevent dust from being deposited on the light receiving surface.

  As shown in FIG. 3, most of the wall-like wall portions 23 described above located in the lower half of the smoke sensing chamber 22 are a wall main body 34 extending along the outer periphery of the housing 21, and a clock of the wall main body 34. The first extension 35 extends in the inner diameter direction from the direction end, and the second extension 36 extends in the inner diameter direction from the counterclockwise end of the wall body 34. The first extension 35 extends in an inclined posture of about 45 ° with respect to the outer peripheral surface of the housing 21. The second extension 36 is further inclined to the right side of the drawing at an angle of about 30 ° from the base end 36a and a short base end 36a extending substantially perpendicular to the inner diameter direction from the counterclockwise end of the wall body 34. The intermediate portion 36b extends and the inclined flange-shaped portion 36c extends right and left from the front end of the intermediate portion 36b.

The wall main body 34 , the first extension portion 35, and the base end portion 36a of the second extension portion 36 cooperate with each other to form a bottomed cup-shaped pocket portion 23P opened to the inner diameter side. ing. The pocket portion 23P has a function of trapping and accumulating dust that has entered the housing 21 mainly through an upper gap at the bottom thereof. Since the bottom surface of the pocket portion 23P is surrounded by the base end portion 36a of the first extension portion 35 and the second extension portion 36, dust accumulated at the bottom portion of the pocket portion 23P is caused by airflow in the housing 21 or vibration transmitted from the outside. There is little possibility of flying up inside the housing 21.

The base end portion 36a, the intermediate portion 36b, and the outer diameter side portion of the flange-shaped portion 36c cooperate with each other to form a bottomed cup-shaped space, and the first extension portion of the wall portion 23 adjacent in the counterclockwise direction. By extending 35 toward this space, a first U-shaped channel is formed on the outer periphery of the first extension 35.
Similarly, the inner diameter side portion of the flange-shaped portion 36c, the intermediate portion 36b, the base end portion 36a, the wall main body 34, and the first extension portion 35 also cooperate with each other to form a bottomed cup-shaped space. The outer diameter side portion of the flange-like portion 36c of the wall portion 23 adjacent to the direction extends so as to enter this space, so that the second U-shaped flow is provided on the outer periphery of the outer diameter-side portion of the flange-like portion 36c. A road is formed.
These two U-shaped flow paths are continuously connected to each other to form one reverse S-shaped labyrinth portion L.

  Generally, due to wind generated in the room where the fire alarm 1 is installed or a slight temperature difference between the inside and outside of the housing 21, the inside of the housing 21 is exposed to the outside through the gap between the plurality of wall portions 23. It is predicted that an airflow that is discharged toward the inside or an airflow that flows from the outside toward the inside is generated. FIG. 4 and FIG. 5 show the results of simulation of these airflows by a computer.

  Among such airflows, the airflow flowing from the outside to the inside of the housing 21 is first counterclockwise with the base end portion 36a of one wall portion 23 as shown in the thick solid line of FIG. 3 and FIG. It enters the labyrinth portion L from between the first extension portions 35 of the adjacent wall portions 23. When passing through the labyrinth portion L, it is guided by the back surface of the intermediate portion 36b and the outer diameter side portion of the flange-shaped portion 36c, and is continuously adjacent in the counterclockwise direction while bypassing the bottom surface of the pocket portion 23P. It is guided radially inward by the intermediate portion 36b of the wall portion 23 and the inner diameter side portion of the flange-shaped portion 36c, and proceeds to the vicinity of the smoke detection region 22A. In other words, the shape of the labyrinth portion L is to prevent a situation in which dust accumulated on the bottom surface of the pocket portion 23P is swung up by the airflow flowing into the housing 21 from the outside to reach the smoke detection region 22A. Designed.

  Next, among the airflows, the airflow flowing from the inside of the housing 21 to the outside first enters the labyrinth portion L through the gap between the flange-like portions 36c adjacent to each other as shown in the broken line in FIG. 3 and FIG. To do. When passing through the labyrinth portion L, it is guided by the outer diameter side portion of the flange-shaped portion 36c, and proceeds so as to scoop up what is on the bottom surface along the shape of the inner surface of the bottom surface of the pocket portion 23P. The air flow then escapes from the pocket portion 23P along the first extension portion 35 and is guided by the intermediate portion 36b of the wall portion 23 and the rear end portion of the base end portion 36a adjacent to each other in the clockwise direction. It goes around the tip and is discharged out of the housing 21. As described above, when the air flow advances along the bottom surface of the pocket portion 23P, the dust collected on the bottom surface of the pocket portion 23P is actively entrained and discharged to the outside.

  In this way, in other words, each part constituting the wall part 23 cooperates with each part constituting the adjacent wall part 23, and the airflow flowing into the housing 21 from the outside bypasses the pocket part 23P. At least a part of the airflow discharged to the outside of the housing 21 constitutes an airflow guide mechanism G that guides the airflow so as to flow along the bottom surface of the pocket portion 23P. The pocket portion 23 </ b> P and the airflow guide mechanism G are mainly disposed at a position centered on the lower side inside the housing 21.

  As shown in FIG. 2, a light shielding wall 28 that blocks direct light from the light emitting unit 25 toward the light receiving unit 26 is disposed between the light collecting unit 25 </ b> L of the light emitting unit 25 and the light collecting unit 26 </ b> L of the light receiving unit 26. It is provided. Accordingly, the light emitted from the light emitting unit 25 does not reach the light receiving element 26 as it is, and the light receiving element 26 receives only scattered light formed by smoke when smoke flows into the smoke sensing chamber 22. .

  In addition, since the light shielding wall 28 is positioned almost directly on the light receiving unit 26, the dust hardly accumulates on the light shielding wall 28 even when dust enters the smoke sensing chamber 22. Further, due to the effect that the optical axes of the light emitting unit 25 and the light receiving unit 26 and the optical axes of the reflecting plate 27 and the light receiving unit 26 intersect at about 90 °, the light shielding wall 28 is slightly smoke detection region. It is located outside 22 </ b> A and is sufficiently away from the axis of the light receiving unit 26. Therefore, even if dust accumulates on the light shielding wall 28, there is little possibility that scattered light formed by the dust is detected by the light receiving unit 26.

Incidentally, if the positional relationship between the light emitting unit 25 and the light receiving unit 26 is set so that the light emitting unit 25 and the light receiving unit 26 are opposed to each other such that the optical axes of the two are about 120 ° to 160 °, for example, Although the detection capability of the scattered light by the part 26 is enhanced, it is necessary to dispose the light shielding wall provided between them in the radial direction. As a result, the possibility of erroneous detection due to scattered light formed by dust accumulated on the light shielding wall increases.
Conversely, when the positional relationship between the light emitting unit 25 and the light receiving unit 26 is set so that the light emitting unit 25 and the light receiving unit 26 are in parallel, such that the optical axes of the two are about 50 ° to 70 °, for example. Since the light shielding wall provided between them can be arranged on the outer side in the radial direction, the possibility of erroneous detection due to scattered light formed by dust accumulated on the light shielding wall is reduced, but the scattered light is backscattered for the light receiving unit 26, so Detection capability is reduced.
That is, when the optical axes of the light emitting unit 25 and the light receiving unit 26 and the optical axes of the reflecting plate 27 and the light receiving unit 26 are set to intersect at about 90 ° as in the present embodiment, the light receiving unit 26 The scattered light detection capability due to the light can be sufficiently obtained, and the light shielding wall provided between them can be disposed relatively outside in the radial direction, so that the possibility of erroneous detection due to scattered light formed by dust accumulated on the light shielding wall can be suppressed.

  The reflecting plate 27 is realized by slightly deforming the flange-like portion 36c of the wall portion 23 disposed to face the light emitting portion 25 and making the inner surface thereof a mirror surface. A dust introduction path 30 is provided on the back surface of the reflecting plate 27 to connect the gap adjacent to the upper side and the space behind the reflecting plate without passing through the reflecting surface of the reflecting plate. The dust that has entered from the gap adjacent to the upper side of the reflecting plate 27 does not pass in front of the reflecting surface of the reflecting plate 27 and is reflected along the dust introduction path 30 as illustrated by a broken arrow in FIG. It is easy to be discharged to the outside from the back surface of 27 through the gap behind the reflection plate 27.

[Another embodiment]
The reflection surface of the reflection plate 27 may be a concave mirror having an appropriate curvature so that the light reflected by the reflection plate 27 toward the smoke detection region 22A does not spread too much.

External view of a fire alarm equipped with a photoelectric smoke detector according to the present invention FIG. 1 is a cutaway front view of a smoke detector provided in the photoelectric smoke detector of FIG. The enlarged view which shows the principal part of the smoke detection part of FIG. Schematic showing the path of airflow from outside to inside Schematic showing the path of airflow from inside to outside

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fire alarm 2 Smoke detection part 3 Alarm speaker part 4 Alarm lamp 21 Housing 22 Smoke detection room 22A Smoke detection area 23 Wall part 23P Pocket part 25 Light emission part 25D Light emission element 25L Condensing lens 26 Light reception part 26D Light reception element 26L Condensing Lens 27 Reflector 28 Light-shielding wall 30 Dust introduction path 34 Wall body 35 First extension 36 Second extension 36a Base 36b Intermediate 36c Flange L Labyrinth G Airflow guide mechanism

Claims (4)

A housing having a plurality of labyrinth-like wall portions juxtaposed via a gap so as to allow smoke from outside and block light from outside;
A light emitting unit for irradiating light inside the housing;
A light receiving unit that detects scattered light from smoke flowing into the housing, and
A reflector that reflects the light emitted from the light emitting unit toward a smoke detection region including a crossing point between the light emitting unit and the light receiving unit is disposed to face the light emitting unit. And
In the installation state in which the plane including the axis of the light emitting unit and the axis of the light receiving unit is vertical, the gap adjacent to the upper side of the reflector and the back of the reflector in the radial direction And a dust introduction path that communicates with each other without passing through the reflecting surface of the reflecting plate ,
Between the labyrinth-shaped wall portion located above the reflector and the reflector, a wall body extending in the circumferential direction, and an extension extending radially inward from both circumferential ends of the wall body, A cross section made of a U-shaped deformed wall is provided,
The dust introduction path is a photoelectric smoke detector formed by two gaps formed above and below the deformed wall portion and an inner peripheral surface of the deformed wall portion . The photoelectric smoke detector according to claim 1 , wherein the reflecting surface of the reflecting plate is arranged so that the reflecting surface is in a vertical or downward posture from the vertical. 3. The photoelectric smoke detector according to claim 1, wherein the light emitting unit and the reflection plate are disposed sideways, and the light receiving unit is disposed immediately above the smoke detection region. The photoelectric smoke detector according to any one of claims 1 to 3, wherein a condensing lens for condensing light from a light source is provided in the light emitting unit.

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