JPH0512871Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to the mesh shape of an insect screen that covers the detection part of a smoke detector and prevents insects from entering from outside.

Figure 1 shows a partial cross-section of a conventional fire detector equipped with a photoelectric or ionization type smoke detector, in which an insect screen 2 is placed around the smoke detector 1 that detects the occurrence of a fire. It is set up. Figures 2 and 3
The figure shows an enlarged view of the mesh shape of a conventional insect repellent net 2, with the openings in FIG. 2 being circular and the openings in FIG. 3 being square. With the shape of such conventional insect nets, there are still areas that need improvement.

That is, the insect screen 2 provided to cover the smoke detection section 1
In addition to preventing the fire detector from malfunctioning due to the invasion of insects from the outside by using the screen, smoke from the outside must flow into the smoke detection section through the openings of the insect screen 2 in a short time. However, the inflow of smoke improves in proportion to the aperture ratio of the insect screen, so the openings must be made larger to improve the inflow, and the paradoxical problem is that if the openings are made larger, the insect control effect decreases. It was hot.

The present invention was developed in view of the above-mentioned problems, and is designed to increase the flow of gas, smoke, and other objects to be detected into the detection part without reducing the insect-proofing effect of the insect repellent net that covers the detection part. The purpose is to provide insect screens and smoke detectors.

In order to achieve this objective, the present invention provides an insect screen with a hexagonal mesh structure around the detection part of the smoke detector to prevent insects from entering from the outside, and to prevent the intrusion of insects from the outside. The aim is to improve the flow of detected objects into the smoke detection section.

Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 4 is an explanatory diagram showing an enlarged part of the insect control net according to the present invention. 3 is a regular hexagonal opening, and 4 is an edge. a is opening 3
is the length of the diagonal. The object to be detected, such as smoke or gas, flows into the smoke detection section through the opening 3. Furthermore, a predetermined width t is set at the edge 4 in order to ensure sufficient mesh strength.

That is, as is clear from the figure, since the insect screen is formed of a single plate, a predetermined width is required to ensure the mesh strength.

Next, the present invention will be explained by comparing it with a conventional mesh shape. First, the area S1 of the opening 3 of the insect screen of the present invention in FIG. 4 is determined by the following formula.

S1={(a/2)+a}×(a/2)×sin60℃=
(3/8)×√3×a ² Further, if S2 is the base area surrounded by the boundaries of mutually adjacent openings indicated by dotted hexagons in FIG. 4, S2 is expressed by the following equation.

S2=(1/2)×[(a/2)+{(t/2)/
sin60°}] ² × sin60°×6=[3×√3×{a+
(2/√3)×t} ² ]/8 Therefore, the area of the opening S1 with respect to the base area S2
The aperture ratio T1 in FIG. 4 is determined by the following equation.

T1=(S1/S2)×100=[a ² /{a+(2t/
√3)} ² ]×100 Similarly, if the diameter of the conventional circular opening 3 in FIG. 2 is a and the minimum width of the edge 4 is t, then the opening 3
The area S3 of , and the base area S4 surrounded by the boundaries of mutually adjacent openings indicated by dotted lines are determined by the following equation.

S3=(a/2) ² π S4={(a/2)+(t/2)}×{(a/2)+
(t/2)}×tan30°×6=(6/√3)×
{(a/2)+(t/2)} ² Therefore, since the aperture ratio T2 in FIG. 2 is the ratio of the area S3 of the aperture and the base area S4, the aperture ratio T2 is expressed by the following formula. It can be done.

T2=(S3/S4)×100=(π/2√3)×
{a ² /(a+t) ² }×100 Furthermore, if the length of the diagonal line of the conventional square opening 3 in FIG. 3 is a, and the width of the edge 4 is t, the area of the opening S5 and the dotted line are The base area S6 surrounded by the boundaries of mutually adjacent openings is determined by the following equation.

S5=(1/2)×a S6={a+{(t/2)/sin45°}×2]×
[(a/2)+(t/2)}sin45°}]={a+
(√2×t)} ² /2 Therefore, since the aperture ratio T3 in FIG. 3 is the ratio of the area S5 of the aperture to the base area S6, the aperture ratio T3 is determined by the following equation.

T3=(S5/S6)×100=[a ² {a+(√2×
t)} ² ]×100 Here, for comparison, the respective aperture ratios T1, T2, T3 in FIG. 4, FIG. 2, and FIG.
For example, the length of a is 0.4 mm, and the value of width t is 0.1.
When calculated assuming the same value in mm, the aperture ratios T1, T2, and T3 are as follows.

Shape of opening Opening ratio Regular hexagon (T1) 60.2% Circle (T2) 58.0% Square (T3) 54.6% Therefore, the insect repellent effect of the insect net is the same, that is,
When the maximum width a of the opening 3 and the width t of the edge 4 are set to the same length, the aperture ratio of the insect screen of the present invention in which the opening 3 has a regular hexagonal shape is maximized,
This proves that even if the insect repellent effect is the same, the inflow effect of smoke and other objects flowing into the detection part through the opening 3 is high. As explained above, according to the present invention, a smoke detector has a smoke detection section that detects smoke generated by a fire, and an insect screen that is disposed around the detection section and prevents insects from entering from outside. Since the insect repellent net is constructed of a single plate and the mesh shape of the insect repellent net is hexagonal, the inflow characteristics of smoke and the like to the smoke detection section can be improved without impairing the insect repellent effect. Conversely, even if the diameter of the mesh is made smaller in order to increase the insect repellent effect, the inflow characteristics will not be impaired. Therefore, if there are many false alarms due to insect intrusion, the same inflow characteristics as before can be obtained even if the mesh diameter is reduced to the extent that the inflow characteristics are not impaired.
In addition, reliability is increased because insects are further prevented from entering. In addition, in areas where insect intrusion is unlikely and smoke needs to be detected faster, increasing the mesh diameter to an extent that does not impair the insect control effect will improve the inflow characteristics and improve the smoke detector's performance. The effect is that the detection time can be shortened.

[Brief explanation of the drawing]

Figure 1 is a partial sectional view of a conventional fire detector, Figure 2 is a partial sectional view of a conventional fire detector.
3 and 3 are partially enlarged views of a conventional insect screen, and FIG. 4 is a partially enlarged view of an insect screen according to the present invention. 1... Smoke detection part, 2... Insect screen, 3... Opening, 4... Edge.

Claims (1)

[Scope of Claim for Utility Model Registration] A smoke detector having a smoke detection part that detects smoke generated by a fire, and an insect screen disposed around the detection part to prevent insects from entering from the outside, A smoke detector characterized in that the insect screen is constructed of a single plate and the mesh shape of the insect screen is a regular hexagon.