JPH0613481Y2 - Smoke detectors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a smoke detector for disaster prevention, and in particular, when smoke enters the box, the light emitted from the light emitter is emitted by the smoke particles. The present invention relates to a smoke detector configured so that a light receiver receives the scattered light and detects the generation of smoke.

(Prior Art) A smoke detector that optically detects smoke entering a box such as a dark box receives light when smoke is not entering the box and when smoke is entering the box. It is desirable that the light receiving ratio in the container is large. Therefore, a smoke sensor has been proposed in which the reflected light reflected by the inner wall surface of the dark box in the smokeless state is improved so that the amount of light received by the light receiver is reduced as much as possible (Actual development) 58-76991,
See Japanese Utility Model Publication No. 60-33515).

This smoke detector has a peripheral wall that becomes a truncated cone in the shape of a truncated cone,
A dark box is configured with an upper wall that closes the upper part of the peripheral wall, and a light emitter that irradiates a substantially horizontal light beam toward the peripheral wall portion facing in the diameter direction of the dark box is provided. A smoke detector that intersects with each other to form a smoke detection area is provided, and a smoke inlet that opens downward is provided at the center of the bottom surface of the dark box, and smoke is introduced from this smoke inlet into the dark box. Immediately into the smoke detection area,
It is designed to provide quick and accurate smoke detection.

(Problems to be solved by the invention) However, in the above-mentioned conventional device, the irradiation direction of the light emitter is directed to the peripheral wall side, the irradiation light is repeatedly reflected many times between the peripheral wall and the upper wall, and the reflected light is reflected. Although it is designed to gradually attenuate and weaken the amount of return light, the return light remains after being repeatedly reflected between the peripheral wall and the upper wall,
Further, since the light emitter is directed only in one direction on the peripheral wall portion and the light receiving area of the light receiver is formed so as to be orthogonal to the light emitting area of the light emitter, the irradiation light is not completely collected on the peripheral wall side. However, there is a problem that the returning light and the slightly leaked scattered light are received by the light receiver.

For this reason, the light reception ratio in the state where there is no smoke and the state where smoke has entered in the dark box is small, and the presence or absence of smoke is unclear. Therefore, when the smoke detection is set to a low concentration range, the output of the detection signal of the smoke detector fluctuates and becomes unstable, which causes a malfunction. Further, the smoke detector is expensive because the light emitter provided in the dark box needs a lens or the like to prevent reflected light from entering the light emitter.

In view of the above points, the present invention is capable of effectively attenuating the reflected light of the light radiated on the inner wall surface of the box with a simple structure and maximizing the effect of stray light due to the return light when there is no smoke. It is an object of the present invention to provide a smoke sensor that can be reduced and that can significantly improve the smoke sensing ability as a whole.

(Means for Solving the Problems) In order to achieve the above object, the smoke sensor according to the present invention comprises:
A disk-shaped lower wall is provided on the lower surface of the diverging circumferential wall,
It has a box body which forms left and right inner chambers narrowed to the peripheral side by the lower wall and the circumferential wall, and irradiates irradiation light toward the acute angle direction of one of the left and right inner chambers. The light emitter is arranged outside the other inner chamber, and the light receiver forming a light receiving region in the direction of the acute angle portion of the other inner chamber is opposed to the light emitter, and the one inner chamber is provided. A smoke detection area is formed at the intersection of the light emitting area of the light emitter and the light receiving area of the light receiver, and a smoke introduction port communicating with the smoke detection area is provided in the box. It is a thing.

(Effect) According to the present invention, the light emitted from the light emitter is located at the peripheral edge side of the box body, and one of the left and right inner chambers of the acute angle portion is formed by the circumferentially diverging circumferential wall and the lower wall provided on the lower surface thereof. Since it is radiated in the direction, in the absence of smoke, reflection is repeated between the inner peripheral wall and the lower wall of the inner chamber, and the reflected light is gradually converged and attenuated inside the sharp corner where the inner chamber is narrowed, and the return There is no light. Further, even if stray light is generated in the box body, the stray light is guided to the inner chamber opposite to the inner chamber and converges and attenuates while repeating reflection between the peripheral wall and the lower wall of the inner chamber. Further, since the light receiving area of the light receiver is also formed toward the acute angle portion of the other inner chamber, it is in a state equivalent to looking at a point at infinity. Therefore, almost no light is received by the light receiver in the smoke-free state, and the difference between the smoked state and the smokeless state becomes clear, and the light-receiving ratio becomes large and the smoke sensing ability is improved.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 to 3, the smoke detector includes a light emitting device 3 and a light receiving device 4 in a box body 1 provided with a smoke introducing body 2 in a lower portion.
It is equipped with.

In the box body 1, an upper surface of a circumferentially-extending circumferential wall 5 is closed by an upper wall 6, and a disc-shaped lower wall 7 is joined to the lower surface of the circumferential wall 5, and the lower wall 7 and the circumferential wall 5 are joined together. Left and right inner chambers 8 and 9 that are narrowed on the peripheral edge side 1a of the box body 1 are formed. And the upper wall 6
At the center of the lower surface of the partition plate 10 with a horizontal plate 10a at its lower end.
Is fixed in a suspended state, and the upper chamber 11 above the box 1 is shielded at the center so that the light emitted from the light emitter 3 does not enter the light receiver 4 side. Further, a smoke intake passage 12 is formed by the lower wall 7 and the smoke introducing body 2, and a plurality of small holes 5a ..., 6a ... Are provided in the peripheral wall 5 and the upper wall 6, and the small hole 5 is formed.
Box body 1 from a, 6a and smoke inlet 7a formed in the lower wall 7
Smoke is introduced inside.

The light emitter 3 emits light toward the acute angle portion 8a in which the left inner chamber 8 on the left side in FIG. 1 is narrowed, and the opening 13a in the diametrical direction of the box 1 has the right inner chamber 9 on the right side in FIG. It is housed in a support cylinder 13 which is located on the outer side of and has a predetermined inclination angle (irradiation angle of the light emitter 3) and which projects from the peripheral wall 5. In addition,
The opening 13a of the support cylinder 13 has a lower surface extending toward the partition plate 10 side to form an extending part 13b. The extending part 13b and the horizontal plate 10a of the partition plate 10 form the light emitting device 3 The irradiation light is made to have a certain vertical width to form a fan-shaped irradiation area A that spreads in the direction of the acute angle portion 8a of the left inner chamber 8 (see FIG. 3).

The light receiver 4 forms a light receiving area B toward the direction of the acute angle portion 9a in which the right inner chamber 9 is narrowed, and receives scattered light from smoke. The opening 14b is formed in the diameter direction of the box body 1 as described above. It is located outside the left inner chamber 8 and is housed in a support cylinder 14 projecting from the peripheral wall 5 at a predetermined inclination angle (light receiving angle of the light receiver 4). The opening 14a of the support cylinder 14 also has an extended portion 14b formed by extending the lower surface toward the partition plate 10 side. The extended portion 14b and the horizontal plate 10a of the partition plate 10 form a light receiver. The light receiving area B of 4 has a certain vertical width and the acute angle portion of the right inner chamber 9
A fan-shaped light-receiving region B extending in the 9a direction is formed. 13c and 14c are lead wires. Thus, the lower wall 7
An area where both areas A and B overlap, that is, a detected smoke area C is formed immediately above the smoke introduction port 7a and below the horizontal plate 10a.

The smoke introducing body 2 is provided in a disk shape so as to cover the smoke introducing opening 7a of the lower wall 7, and a smoke intake passage 12 communicating with the smoke introducing opening 7a is formed between the smoke introducing body 2 and the lower wall 7. To be done. Further, as shown in FIG. 2, four small holes 6a are provided on the peripheral surface of the upper wall 6 at equal intervals, and eight inclined holes 6a are formed on the inclined surface of the peripheral wall 5 at predetermined intervals. The small hole 5a is formed so that the smoke intake efficiency into the box 1 is increased in cooperation with the smoke intake passage 12.

The small holes 5a and 6a may be provided only on either the peripheral wall 5 or the upper wall 6, and the number thereof is not limited. The box body 1 is provided with a plurality of small holes.
Even if the light beam of the fluorescent lamp enters the inside, the influence of the ambient light can be avoided by changing the wavelength of the light of the light emitter 3 and the light receiver 4.
Further, the inner surface of the box body 1 and the upper surface 2a of the smoke introducing body 2 are black with a high light absorptivity, and in particular, the inner surfaces of the inner chambers 8 and 9 are rough surfaces in order to enhance the absorbability.

Further, the irradiation area A of the projector 3 and the light receiving area B of the light receiver 4 are such that the vertical widths thereof are the horizontal board 10a and the extending portions 13b, 14b.
Although it is possible to adjust with, the slits having a predetermined width may be formed in each of the openings 13a and 14a. Thereby, the vertical width of the luminous flux can be set, so that the partition plate 10 can be omitted.

(Operation of Embodiment) With the above-described configuration, first, in the smokeless state, as shown in FIGS. 1 and 3, the light emitted from the light emitter 3 emits light to the peripheral wall 5 of the left inner chamber 8. And the lower wall 7 and strikes an acute angle portion 8a to be reflected. Although this reflection is initially performed on the large diameter side of the left inner chamber 8, the reflection is repeated between the peripheral wall 5 and the lower wall 7, and gradually converges toward the inner depth of the acute angle portion 8a and attenuates. At this time, even if the irradiating light impinges on the partition plate 10 or the like and is refracted to become stray light 1 which continues to be diffusely reflected, this stray light 1 is still generated.
The light is repeatedly reflected by the peripheral wall 5 and the lower wall 7 and converges to the inner depth side of the acute angle portion 9a and is attenuated. This allows reflected light and scattered light to
Since the light is guided to the left and right inner chambers 8 and 9, the light is hardly received by the light receiver 4. Further, when the irradiation hits the partition plate 10 or the like,
Even if it is refracted and enters the upper chamber 11 side, the light receiver 3,
Since the partition plate 10 that shields 4 is provided in a hanging shape,
The scattered light is prevented from being received by the light receiver 4. Even if temporary scattered light or stray light is received by the light receiver 4, the amount of received light is extremely small. Moreover, since the light emitter 3 is directed toward the acute angle portion 8a of the left inner chamber 8 with a predetermined inclination angle, the irradiation light is linearly incident on the acute angle portion 8a and converges. Is abruptly weakened, and in conjunction with this, the amount of received light can be reduced. The number of reflections of the reflected light can be appropriately increased by thinning the box body 1 and reducing the inclination angle of the peripheral wall 5 with respect to the lower wall 7. Therefore, the received amount of the reflected light is minimized in the smokeless state. As a result, it is possible to increase the light receiving ratio when there is smoke.

Next, in the smoked state, when the smoke that has entered from the smoke inlet 7a reaches the smoke detection region C, the light emitting device 3 is caused by the smoke particles.
The light emitted from is scattered and this scattered light is received by the light receiver 4
Receives light. This smoke detection is output as a detection signal and input to an alarm means (not shown) via the lead wire 14c. At this time, since the smoke detection area C is formed substantially in the middle of the smoke introduction port 7a in the lower part of the box 1 and the small holes 5a, 6a in the upper part, which have good smoke flowability, the introduction of smoke is extremely smooth and quick. The smoke detection ability is improved. Further, since the light emitting area A and the light receiving area B spread in a fan shape with a predetermined inclination, and the smoke detection area C at the intersection is large, the smoke sensing effect is good and reliable regardless of the density of the smoke. To be done.

By the way, in this type of smoke detector, since the light receiving rate varies depending on the shape of the box body 1, it also affects the clarity of the smokeless state and the smoked state. Then, this clarity can be generally obtained as an S / N ratio based on the level of the signal output from the light receiver 4, and can be grasped as a characteristic of the smoke detector.

FIG. 4 is a graph showing the S / N ratio of this example and the conventional smoke detector.

In addition, S: Signal output of the light receiver in a smoked state where smoke has entered the box body N: Signal output of the light receiver in a smokeless state where no smoke has entered the box body X: Measurement of the smoke sensor of this embodiment Value Y: Measured value of a smoke sensor of a conventional example (smoke sensor of Japanese Utility Model Publication No. 60-33515) As is apparent from the figure, when smoke density is 0 and no smoke is present, both X and Y are S / N. When the ratio is 1 and the receiver 4 receives a small amount of light, the S / N increases as the smoke density increases.
It was clarified that there was a large difference in the slope of the straight line showing the ratio. For example, when the smoke density is 10%, Y is about 8 times, whereas X is about 20 times. This indicates that, under the same conditions, the ability to detect the presence or absence of smoke entering the smoke detector greatly depends on the structure of the smoke detector.
In the case of the present Example X, it became clear that the clarity of the presence / absence of smoke was dramatically improved as compared with the conventional example Y. Therefore, there is a difference in the output level indicating the sensing ability when the smoke sensor is set to a predetermined sensing smoke density and used.

FIG. 5 is a graph showing the output levels of this embodiment and the conventional smoke detector.

As is clear from the figure, when the smoke density O is sequentially increased, the detected smoke density of the conventional example Y is S ₂ until the level of the output signal from the light receiver 4 reaches a constant value. It can be seen that this Example X is achieved at a lower concentration of S ₁ than S ₂ . This indicates that even low-concentration smoke can be extremely quickly responded to, and safety for disaster prevention can be enhanced.

On the other hand, when the detected smoke density for operating the smoke detector is set to a predetermined set value, for example, the range ΔS between S ₃ and S ₄ , and used, the signal output level of the light receiver 4 is ΔV ₂ for Y. In contrast, the output level ΔV ₁ of X is ΔV ₁ > ΔV _2, and it is clear that the output level difference is also significantly different. As a result, in the comparison circuit of the alarm means, when compared with the reference value for alarm issuance, it is easy to cause a state in which the difference from the reference value becomes unclear at a low output level as in the conventional case, and the determination is unstable. However, if a high output level is output as in this example, the difference from the reference value becomes clear, so always perform an accurate alarm operation. You can Moreover, when the smoke density is set to a low range and used, if the signal output level is low as in the conventional case, the comparison circuit and the like are required to have high accuracy, but in the low density range like this example. If a high output is obtained, high-precision electronic parts are not required, and the reference value adjustment of the comparison circuit can be performed roughly. Even if the output level fluctuates due to secular change in the usage state, in this example, the output level is always maintained in a wide range, so that stable operation can be performed, temperature change and electronic component Malfunction due to deterioration can be avoided. If you lower the smoke density setting value, the detection limit will occur.
When the output level is wide as in this example, the detection limit point can be made considerably lower than in the conventional case, and there is an advantage that the applicable range of the installation place is widened.

(Effects of the Invention) As described above, according to the present invention, the irradiation light from the light emitter is formed on the peripheral side of the box body by the divergent circumferential wall and the lower wall provided on the lower surface thereof. Is irradiated toward the acute-angled portion of the inner chamber, and while repeating reflection between the inner peripheral wall and the lower wall forming the acute-angled portion, is gradually converged and attenuated while being guided to the inner side of the inner chamber, The return light can be turned off. Further, since the light receiving area of the light receiver is also directed to the acute angle portion of the other inner chamber, it is possible to reduce the influence of stray light to the maximum, which is equivalent to looking at a point at infinity. Therefore, since the difference between the smoked state and the smokeless state becomes clear, the light reception ratio becomes large, and the smoke sensing ability can be significantly improved. As a result, malfunction is avoided and safety in disaster prevention is improved. There is an effect such as being able to.

[Brief description of drawings]

The drawing shows one embodiment of the present invention. Fig. 1 is a vertical sectional front view of a smoke detector, Fig. 2 is a plan view of the same, and Fig. 3 is III-I of Fig. 1.
FIG. 4 is a graph showing the S / N ratio of the smoke detector, and FIG. 5 is a graph showing the output level of the output signal of the smoke detector. 1 …… Box 2 …… Smoke introduction body 3 …… Light emitter 4 …… Receiver 5 …… Peripheral wall 8,9 …… Inner room

Claims (1)

[Scope of utility model registration request] 1. A box-shaped body having a disk-shaped lower wall provided on a lower surface of a circumferentially diverging circumferential wall, and the left and right circumferential walls constricting left and right inner chambers. Of the left and right inner chambers,
A light emitter that irradiates irradiation light toward the acute-angled portion of one inner chamber is arranged outside the other inner chamber, while forming a light-receiving region toward the acute-angled portion of the other inner chamber. The photodetector is opposed to the light emitter and is disposed outside the one inner chamber to form a smoke detection area at a crossing point between the irradiation area of the light emitter and the light receiving area of the light receiver. A smoke detector characterized in that a smoke introduction port communicating with a smoke detection area is provided in the box body.