RU35022U1 - SMOKE FIRE DETECTOR - Google Patents

Description

SMOKE FIRE DETECTOR

The utility model relates to the field of automatic fire alarms, and more specifically to fire detectors that detect the appearance of smoke in the area of their installation.

Smoke detectors operating on the principle of recording scattered radiation are widely known. For example, a smoke detector by a.s. USSR No. 575672, G 08 B 17/10; smoke detector USSR jYo 1265821, G08B17 / 10; scheme for detecting a decrease in the sensitivity of the photoelectric smoke detector, Japanese application No. 4-60276, No. 4-60277, G08B17 / 107.

These detectors use a built-in emitting LED and a recording photodiode located in a sensitive camera at an obtuse angle to one another. Under clean air conditions, the photodiode does not detect the emission of the LED. When smoke enters through openings in the walls of the sensitive chamber, the LED radiation scattered by the smoke particles is detected by the photodiode. The signal from the photodiode is transmitted to a decisive device and when the signal reaches a predetermined threshold level, the detector switches to alarm state. However, the luminous flux incident on the photodiode can also be due to the reflection of the LED radiation from the dusty walls of the sensitive chamber or to the light penetrating through its openings.

2003122412

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G 08 V 17/10

The closest to the proposed technical essence and the achieved result is a detector smoke optical-electronic smoke ECO2003 company System Sensor. Specialized information and technical zhfnal on fire and security protection, information and communication, December 1997 / February 1998, p.13; European Patent Application EP 1,049,060 A2. The detector contains an emitting LED that detects a photodiode, i.e. an optical pair housed in a sensitive chamber that is directly connected to an additional dust collection chamber.

The aerodynamic resistance of the additional chamber (Qj), which affects the speed and nature of the propagation of air flows through the chamber, is proportional to the ratio of the path length (Li, Fig. 2), which is necessary to pass the air flow from the analyzed volume to the sensitive element (optical pair), and surface area additional chamber (Si) in contact with the analyzed volume:

The surface area of the additional chamber (Si) is determined by the following ratio:

e-V / cx ..

/ ilrv ((v /; /

.-- -)

at

,

S, 27rRiHi;

RI is the distance from the geometric axis of the detector to the outer wall of the additional camera (Fig. 2).

HI is the height of the smoke channel in the additional chamber (Fig. 2). The disadvantages of the prototype include the fact that the design of the additional camera does not allow reliable protection of the sensitive camera from dust particles. Dust suspended in the streams of the analyzed air, not meeting enough obstacles in its path, enters the sensitive chamber and settles in it. As a result, in order to maintain the required parameters of the detector, it is necessary to relatively often clean the surfaces of the emitting LED, the registering photodiode, and the sensitive chamber from contamination.

In addition, the structure of the smoke channel in the additional chamber does not provide complete protection of the detector sensitive elements from background illumination, as well as the same sensitivity to vertical and horizontal directional smoke streams.

The technical problem that this utility model is aimed at is increasing the sensitivity of the detector to smoke streams of various directions, increasing the time interval between cleaning the sensitive chamber of the detector by reducing its pollution, and also reducing the influence of background illumination on the correct operation of the detector.

The problem is solved in that in a smoke fire detector containing an optical pair placed in a sensitive chamber and an additional chamber, the additional chamber is provided with at least three ribs, one of which is located between two others located on the opposite wall of the chamber.

In accordance with paragraph 2 of the utility model formula, the outer wall of the additional chamber is perforated and is inclined to the base.

Obviously, the placement of additional ribs, significantly increasing the path (Li, Fig. 3) of smoke passage from the analyzed volume to the sensitive chamber compared to the prototype, which, all other things being equal, would increase the aerodynamic drag of the additional chamber (2), making it more difficult for smoke to propagate smoke channel.

However, with the claimed solution, the surface area (82) of the additional camera, which is in direct contact with the analyzed volume, is also increased by increasing the distance from the geometric axis of the detector to the outer wall of the additional camera (R, Fig. 3):

L, L2

HI is the height of the chimney in the secondary chamber. The surface area of Si is increased so much that the aerodynamic drag of the additional chamber (2):

remained at least unchanged, and, therefore, the sensitivity of the detector did not deteriorate.

The essence of the utility model is illustrated in the drawing, which shows:

FIG. 1 is a diagram of a proposed detector;

FIG. 2 - the passage of the analyzed air in the prototype;

FIG. 3 - diagram of the passage of the analyzed air in the proposed detector.

The smoke detector contains (Fig. 1) a sensitive chamber 1 in which an optical pair 2 is placed. The sensitive chamber is separated from the secondary chamber 3 by a rib 4. In the secondary chamber 3 there are ribs 4, 5 and 6 and a perforated outer wall 7 inclined to the base The rib 6 is located on the opposite wall 8 of the additional chamber 3.

The inclined location of the perforated outer wall 7 allows you to increase sensitivity to both horizontal and vertical streams of smoke.

Q2 L2 / S2 Under clean air conditions, the photodiode does not detect radiation

LED, since in the optical pair 2 located in the sensitive chamber 1, the emitting LED and the recording photodiode are at an obtuse angle to one another. When a fire occurs, smoke passes through the perforated outer wall 7 of the additional chamber 3, collides with the ribs 4, 5 and 6 and passes into the sensitive chamber 1. At each collision, heavy dust particles settle in special cavities of the additional chamber and do not enter the sensitive chamber. Thus, contamination of the sensitive chamber is minimized. When smoke enters the sensitive chamber 1, the scattered light is detected by the photodiode of the optical pair 2. The signal from the photodiode is sent to the device, which makes a decision about the alarm when the specified signal level is reached.

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- 6 FORMULA

Claims (2)

1. A smoke fire detector containing an optical pair housed in a sensitive chamber and an additional chamber with a smoke inlet, characterized in that the additional chamber is provided with at least three fins, one of which is located between two others located on the opposite wall of the chamber. 2. Smoke detector according to claim 1, characterized in that the outer wall of the additional chamber is perforated and is inclined to the base.