JPH1151864A - Photoelectric smoke sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve property of smoke to get into a part where the smoke is hard to enter and improve smoke sensing performance by setting a cylindrical wall between a cover having a smoke entrance opening and a labyrinth forming an optical chamber inside. SOLUTION: A photoelectric smoke sensor has a cover 1 constituting a part of a housing and a labyrinth 2 arranged inside the cover. A light-emitting element and a photodetector are set inside the labyrinth 2, and ribs 10, 10 of a nearly circular cross section are set as a smoke direction-changing body between the cover 1 and labyrinth 2. A smoke passing through smoke entrance openings 6 is pulled and drawn by the ribs 10, 10 in the vicinity of the ribs, and eventually flow into an opening part of the V-shaped labyrinth 2. The ribs 10, 10 can be suitably replaced with circular ones among electronic parts for forming the photoelectric smoke sensor. Even prism-shaped electronic parts attain the same effect if arranged in a proper direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric smoke detector.

[0002]

2. Description of the Related Art As shown in FIG. 3, a conventional photoelectric smoke detector has a labyrinth 2 inside a cover 1 integrally formed as a housing of the photoelectric smoke detector, and an optical chamber in the labyrinth 2. The light-emitting element 3 and the light-receiving element 4 are provided in the optical chamber. When smoke from a fire enters, the light from the light-emitting element 3 is scattered by the smoke and enters the light-receiving element 4 to generate a light-receiving current. Let's detect the smoke.

When the photoelectric smoke detector is used for ordinary households, the photoelectric smoke detector has a built-in dry cell, an alarm buzzer, a warning display lamp, and a cord for stopping the alarm. Etc., and the housing is large compared to the photoelectric smoke detector for the system. As shown in FIG. 3, a smoke inlet 6 is formed in the cover 1 constituting the housing, and the labyrinth 2 and the rib 5 are arranged inside the cover 1.

[0004]

However, for example, when smoke flows in the direction shown by the arrow in FIG.
There is a problem that the smoke hits the outer wall of the labyrinth 2 and the smoke hardly flows into the labyrinth 2.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a photoelectric smoke sensor having improved smoke inflow at a portion where smoke is difficult to flow. It is in.

[0006]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, light from a light-emitting element is scattered by smoke and is incident on a light-receiving element to detect smoke. In the smoke detector, a cover having a smoke inlet and a labyrinth disposed in the cover are provided, and a smoke direction changing body having a circumferential wall is provided between the cover and the labyrinth.

According to a second aspect of the present invention, in a photoelectric smoke detector for detecting smoke by scattered light from a light emitting element due to smoke and incident on a light receiving element, a cover having a smoke inlet and a cover inside the cover are provided. And a rib having a circumferential wall is provided between the cover and the labyrinth.

According to a third aspect of the present invention, in a photoelectric smoke detector for detecting smoke by scattered light from a light emitting element due to smoke and incident on a light receiving element, a cover having a smoke inlet and a cover inside the cover are provided. And an electronic component having a substantially circular cross section is disposed between the cover and the labyrinth.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a plan view of a main part of a photoelectric smoke detector, and FIG. 2 is a view showing a direction of smoke flow.

As shown in FIG. 1, the photoelectric smoke detector has a cover 1 forming a part of a housing and a labyrinth 2 disposed inside the cover. The labyrinth 2 forms an optical chamber inside, and also allows smoke to flow while blocking disturbance light. The labyrinth 2 also has a function of condensing water vapor. In the case of FIG. 1, since it is difficult to provide the smoke inlet 6 at the corner 1a of the cover 1, it is difficult for the smoke to reach the labyrinth 2 at a portion facing the corner 1a.

Therefore, in this embodiment, ribs 10 having a substantially circular cross section are formed between the labyrinth 2 and the cover 1 as a smoke direction changing body having a circumferential wall. The ribs 10 may be integrally formed so as to protrude from the cover 1 so as to simultaneously reinforce the strength of the cover 1.

When the ribs 10 and 10 are formed as shown in FIG. 1, the smoke flows so as to entangle the ribs 10 and 10 as shown by the arrows in FIG. 1 and flows into the opening of the labyrinth 2 having a dogleg shape. You can do so.

The phenomenon in which this smoke flow occurs will be described with reference to FIG. When the smoke that has passed through the smoke inlet 6 comes close to the rib 10, the airflow A shown in FIG. That is, the pressure of the airflow A is lower than that of the airflow D, and the airflow A can be pulled toward the ribs 10 even after passing around the ribs 10 and change the direction of the airflows.

The ribs 10 shown in FIG. 1 may be replaced by electronic components mounted on a printed circuit board (not shown) provided on a plane parallel to the plane on which the labyrinth 2 is formed.
For this electronic component, an electronic component necessary for forming a photoelectric smoke detector can be used, and for example, a cylindrical electronic component can be appropriately used in a capacitor, a sensitivity adjustment volume, a thyristor, a resistor, and the like. . Further, even in the case of a rectangular column-shaped electronic component, if the side wall of the electronic component is disposed in an appropriate direction, the same effect as that of a columnar (circular cross-section) can be obtained.

[0015]

According to the first aspect of the present invention, after the smoke has flowed into the cover, the flow direction of the smoke can be changed, so that the flow of the smoke at a portion where the smoke is difficult to flow into the labyrinth is improved. As a result, the smoke detection performance of the photoelectric smoke detector can be improved.

According to the second aspect of the invention, in addition to the effect of the first aspect, the effect that the inflow direction of the smoke can be changed by using a rib required for the cover of the photoelectric smoke sensor. Play.

According to the third aspect of the invention, in addition to the effect of the first aspect, there is an effect that the inflow direction of the smoke can be changed by using electronic components necessary for the photoelectric smoke detector. .

[Brief description of the drawings]

FIG. 1 is a plan view of a main part of a photoelectric smoke detector according to an embodiment of the present invention.

FIG. 2 is a view showing a direction of a flow of smoke of the above.

FIG. 3 is a plan view of a main part of a conventional photoelectric smoke detector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cover 2 Labyrinth 3 Light emitting element 4 Light receiving element 6 Smoke inlet 10 Smoke direction change body (rib, electronic parts)

Claims (3)

[Claims] 1. A photoelectric smoke detector for detecting smoke by scattered light from a light-emitting element due to smoke and incident on a light-receiving element, comprising: a cover having a smoke inlet; and a labyrinth disposed in the cover. And a smoke direction changing body having a circumferential wall is provided between the cover and the labyrinth. 2. A photoelectric smoke detector for detecting smoke by scattered light from a light emitting element due to smoke and incident on a light receiving element, comprising: a cover having a smoke inlet; and a labyrinth disposed in the cover. And a rib having a circumferential wall is disposed between the cover and the labyrinth. 3. A photoelectric smoke detector for detecting smoke by scattered light from a light emitting element due to smoke and incident on a light receiving element, wherein a cover having a smoke inlet and a labyrinth disposed in the cover are provided. And an electronic component having a substantially circular cross section is disposed between the cover and the labyrinth.