JP5117820B2 - Photoelectric smoke detector - Google Patents

Description

  The present invention includes a housing having a plurality of walls that allow external smoke to flow in and blocks direct light from the outside, a light emitting unit that irradiates light inside the housing, and a smoke sensing chamber. The present invention relates to a photoelectric smoke detector including a light receiving unit that receives the scattered light of the light caused by smoke flowing into the inside.

  Conventionally, a photoelectric smoke detector is provided with a light emitting unit that emits light and a light receiving unit that receives light in a smoke detection chamber formed by a housing, and smoke flows into the smoke detection chamber. In addition, the light is scattered by the smoke, and the smoke is detected by detecting the scattered light.

  In such a photoelectric smoke sensor, smoke from the outside passes through the housing but a plurality of labyrinth walls etc. that block the light from the outside are provided, and the detection accuracy of the scattered light by the smoke in the light receiving unit is improved, An insect screen is provided outside the wall portion to prevent false detection due to insects entering the smoke detection chamber (see, for example, Patent Document 1).

JP-A-9-231485

  However, the insect net used in the conventional photoelectric smoke detector is provided with a gap that does not affect the inflow of smoke so as not to hinder the smoke detection performance. For this reason, small dust may enter the smoke detection chamber from this gap, and once it has entered, it is difficult for the dust to enter the smoke detection chamber due to the insect screen. When dust enters the smoke detection chamber, the light emitted from the light emitting part may be diffusely reflected, and the intensity of the diffusely reflected light is approximately the same as the intensity of the scattered light from the smoke, causing a problem of false detection. .

  In addition, dust that has entered the smoke detection chamber may accumulate in a position where the light emitted from the light emitting unit does not strike. Even in this case, when air or the like flows from the outside into the smoke detection chamber, the dust or the like again rises into the smoke detection chamber and moves to a position where the light from the light emitting unit is irregularly reflected, thereby causing erroneous detection.

  The present invention has been made in view of the above problems, and an object thereof is to provide a photoelectric smoke detector that is difficult to detect erroneously.

In order to achieve the above object, the photoelectric smoke detector according to the present invention includes a housing having a plurality of walls that allow external smoke to flow in and blocks direct light from the outside, and the housing. A light emitting unit that irradiates light inside, and a light receiving unit that receives the scattered light of the light due to the smoke flowing into the housing, and in a state where the housing is attached to a vertical wall, at least of the wall portions Provided in the lowermost wall portion is a pocket portion that opens upward to capture dust that has entered the interior of the housing, and the light receiving portion is located above the pocket portion. It is in the point provided.

In a state where the housing is attached to the wall, dust that has entered the inside of the housing tends to accumulate downward.
For this reason, in the state where the housing is attached to the wall as in this configuration, the pocket portion is provided at least at the lowermost wall portion so as to open upward, thereby capturing dust and Light irregular reflection can be prevented and erroneous detection can be prevented.

  The dust trapped in the pocket portion can be blocked from the air or the like by the pocket portion even when external air or the like flows into the housing. For this reason, dust can be prevented from rising inside the housing.

  In addition, when the housing is used with the housing attached to the wall, dust tends to enter the housing from above. For this reason, by providing the light receiving portion above the pocket portion provided at the lowermost portion, the light receiving portion can function to remove dust so that it is difficult for dust to enter the inside of the housing.

  Hereinafter, an embodiment of a photoelectric smoke detector according to the present invention will be described with reference to the drawings. Here, the case where this invention is applied to the smoke detection part 2 in the fire alarm 1 is demonstrated.

  As shown in FIG. 2, the fire alarm device 1 according to the present embodiment has a smoke detection unit 2 that detects smoke, an alarm speaker 3 that emits an alarm sound such as a voice or a buzzer, and light from an LED or the like on the front. And an alarm lamp 4 that lights or blinks. 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. If the smoke concentration exceeds the threshold value, the fire alarm 1 is determined to be a fire. Then, an alarm sound is emitted from the alarm speaker 3 and the alarm lamp 4 is turned on. The fire alarm 1 is provided with an alarm stop button 5, which can be operated to stop an alarm sound from the alarm speaker 3 and turn off the alarm lamp 4. Also, on the back of the fire alarm 1, there are 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. It is provided.

  As shown in FIG. 1, the smoke detection unit 2 includes a housing 21 having a smoke detection chamber 22 that detects smoke therein. A plurality of bowl-shaped wall portions 23 are provided in the housing 21 so as to surround the smoke detection chamber 22 over the entire length in the height direction of the smoke detection chamber 22. Thereby, the smoke from the outside can flow into the smoke detection chamber 22 while blocking the light from the outside. Each wall portion 23 is provided with its end portion directed in the same circumferential direction, and on the wall portion 23a provided at the lowest position of the wall portion 23 when the fire alarm 1 is attached to the wall. Is formed of a wall having the same height as the other wall portions 23, and is provided with a pocket portion 23b that opens upward. An insect screen 24 made of a wire mesh or the like is provided outside the wall portion 23 so that insects and the like do not enter the smoke detection chamber 22.

  In the wall-mounted fire alarm 1 as in the present embodiment, dust that has entered the smoke detection chamber 22 accumulates downward. For this reason, by providing such a pocket portion 23b, dust that has entered the smoke detection chamber 22 can be efficiently captured. Further, the end portion of the wall portion 23a forming the pocket portion 23b on the side of the smoke detection chamber 22 is provided so as to face the same circumferential direction as the end portion of the wall portion 23 on the other smoke detection chamber 22 side. 1 flows in the direction opposite to the pocket 23b and flows in between the wall 22 on the right side of the wall 23a in FIG. Are configured to flow through the upper portion of the pocket portion 23b. For this reason, air or the like flowing from the outside does not flow into the pocket portion 23b, and dust once trapped in the pocket portion 23b does not rise.

  In the present embodiment, the opening width of the pocket portion 23 b is set to be approximately the same as the opening width of the light receiving element 26. The opening width of the pocket portion 23b is preferably large within a range that does not hinder the inflow of smoke into the smoke detection chamber 22, thereby facilitating dust capture.

  Inside the housing 21 are a light emitting element 25 such as a light emitting diode that irradiates the smoke detection chamber 22 with light such as near infrared rays, and a photodiode as a light receiving portion that receives the light from the smoke detection chamber 22. The light receiving element 26 is provided such that the respective optical axes intersect within the smoke detection chamber 22. Further, a light shielding wall 27 is provided between the light emitting element 25 and the light receiving element 26 so that direct light from the light emitting element 25 toward the light receiving element 26 can be blocked. For this reason, the light receiving element 26 does not normally receive the light emitted from the light emitting element 25 and can receive the scattered light of the light emitted from the light element 25 due to the smoke only when the smoke flows into the smoke detection chamber 22. Become. The smoke detector 2 can detect the presence of smoke by detecting the scattered light.

  The light receiving element 26 is disposed so as to be positioned above the pocket portion 23b. In the wall-mounted fire alarm 1 as in this embodiment, dust easily enters the housing 21 from above. For this reason, by providing the light receiving element 26 and the pocket portion 23 b in this way, dust is less likely to enter the smoke detection chamber 22. The light emitting element 26 is not preferably provided above the pocket portion 23b. When the light emitting element 25 is provided above the pocket portion 23b, the direct light from the light emitting element 25 hits the dust trapped in the pocket portion 23b and easily diffuses.

  As described above, in the fire alarm device 1 according to this embodiment, it is difficult for dust to enter the inside of the smoke detection chamber 22, and the dust that has entered can be captured by the pocket portion 23b. It is possible to prevent the light irradiated by the light from being irregularly reflected and to prevent erroneous detection.

  In addition, about the structure and function of the fire alarm 1 provided with the other smoke detection part 2, it is the same as that of a conventionally well-known fire alarm.

[Another embodiment]
In the above embodiment, an example in which one pocket portion 23b is provided has been described, but a plurality of pocket portions 23b may be provided. In this case, in addition to the lowest position, it can be provided at any position where dust is more likely to accumulate from the airflow generated by the shape of the wall portion 23 and the like.

  In the above embodiment, the example in which the pocket portion 23b is formed of the same material as that of the wall portion 23 has been described, but the present invention is not limited to this. For example, the pocket portion 23b can be formed of a member that easily adsorbs dust, such as an adhesive member or a chargeable member. This makes it easier to capture dust.

  The photoelectric smoke detector according to the present invention can be applied to a smoke sensor that detects smoke, an alarm device that detects smoke and issues an alarm, a measuring device that measures smoke concentration, and the like.

Plan sectional view of the smoke detector according to the present embodiment Schematic diagram of fire alarm according to this embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fire alarm 2 Smoke detection part 21 Housing 23 Wall part 23a Wall part 23b Pocket part 25 Light emitting element (light emission part)
26 Light receiving element (light receiving part)

Claims (1)

A housing having a plurality of wall portions that allow smoke from the outside to flow in and block direct light from the outside; and
A light emitting unit for irradiating light inside the housing;
A light receiving portion that receives the scattered light of the light due to the smoke flowing into the housing,
In a state where the housing is attached to a vertical wall, a pocket portion that captures dust that has entered inside the housing is provided so as to open upward in a wall portion located at least at the lowermost portion of the wall portion. The photoelectric smoke detector is provided so that the light receiving portion is positioned above the pocket portion.

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