JPH0820363B2 - Fire detector - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fire detector having a chamber equipped with a sensor. The above-mentioned sensor is a sensor for detecting combustible substances such as an optical smoke sensor.

[Conventional technology]

As is known in the art, an optical sensor includes a light emitting diode (LED) as a light emitting device and a photodiode as a light receiving device arranged in a room accessible to smoke from the outside air. The optical axes of the light emitter and the light receiver are usually arranged in the room at an angle to each other. These optical axes are designed to meet in the central region of the chamber where smoke first emerges and detect efficiently. Angle here refers to the angle in the vertical plane when the fire detector is usually mounted on the ceiling, and there is no direct light transmission path between the light emitter and the light receiver.
The above is intended to ensure that the false reflections from the light emitter reach the light receiver.

[Problems to be solved by the invention]

Fire detectors using such optical sensors have many optical difficulties. Smoke usually enters the room through the net, but it is not possible to make the size of the net small enough to prevent the entry of very small insects, which causes light scattering by the invading insects. You will be alerted to the mistake. Also, with conventional mesh arrangements, smoke carried by the gas stream impinges on the detector from different directions in the vertical plane and thus cannot be repeatedly detected. Such hits from various directions are usually due to changes in the velocity of the gas flow.

It is an object of the present invention to provide a fire detector having excellent detectability and having an optical sensor arranged in the room to reduce false alarms caused by objects such as insects. .

Another object of the present invention is to provide a particle or gas detector which is superior to the prior art in changing the velocity of a gaseous medium.

[Means for solving problems]

According to the present invention, there is provided a fire detector disposed on an installation surface such as a ceiling surface, the room having a substrate and opening to the outside air, and the fire detector is installed in a peripheral area of the substrate. Located on a single plane that is preferably parallel to the horizontal plane, and a pair of inclined recesses facing each other are formed inside the peripheral region of the substrate. Formed to meet at a generally central ridge extending transversely such that the light emitter has an optical path directed along said recess at the end of one of the recesses remote from said ridge. A fire detector mounted such that the optical receiver has an optical path at the end of the other recess remote from the ridge, with opposite optical paths along the recess. Formed at different angles to a single plane, so that The optical axis of the optical unit and the light receiver,
Encountered at an angle of 170 ° to 135 ° at a location in the chamber substantially laterally spaced from the ridge, the optical paths being 3 ° to 12 ° in a plane parallel to the plane containing the peripheral region. A fire detector is provided which is arranged at an angle of.

According to the present invention, there is also provided a particle or gas detector installed on a flat surface such as a ceiling surface, including a sensor, through one or more openings extending in a plane substantially parallel to the installation surface. In a room provided with a chamber open to the outside, a part of the casing of the fire detector extends outside the opening and at least a part of the gas flow flowing substantially parallel to the plane of the opening is deflected to the plane of the opening. A particle or gas detector configured to pass at a right angle is provided.

〔Example〕

 Embodiments of the present invention will be described below with reference to the accompanying drawings.

The fire detector includes a cup-shaped main body 1 to be attached to a ceiling 2, a substrate 3, a casing 4, and a substantially flat ring net 5.
The chamber 4 is defined by the casing 4 and the substrate 3. The opening area of the net 5 is preferably 1 mm ² or less so that the fire alarm does not sound when insects fly in. However, the opening size of the mesh cannot be made too small. If the opening size is made too small, it will prevent the passage of smoke.

The body 1 comprises a box 7 having pillars 8, said pillars 8 carrying jaws 9 and 10 carrying radial edges 11 of a printed circuit board 12.
Have. Each jaw 9, 10 has a flexible electrical wiper connector 13 that contacts fixed contacts (not shown) on the circuit board 12.
Is provided.

The substrate 3 has a circular shape, and an upright wall 15 is formed in a flat peripheral region 14 of the substrate 3, and a shoulder portion 16 is formed inside the upper portion of the upright wall 15. Inside the region 14, the substrate 3 is formed with an arcuate ridge 17 which is offset from the center line of the substrate.
The upper surface 18 of the ridge 17 lies in the plane containing the upper surface of the region 14. Also, as shown in FIG. 2, the ridge 17 is tapered from the ridge end 19 to the wide end 20 and is similarly formed with a tapered central groove 21. The centerline of the central groove 21 is offset with respect to the substrate and is tilted from the centerline of the substrate by a small angle, for example about 2 °.

Inclined portions 22 and 23 are formed on both sides of the ridge 17 up to horizontal flat portions 24 and 25. Slope 22 and horizontal flat 2
The first groove 26 extending to the end 27 is provided on the base 4, and the second groove 28 reaching the end 29 is provided on the inclined portion 23 and the flat portion 25.
As shown in FIG. 2, the groove 26 lies on the centerline 30,
28 is inclined by an angle A with respect to this center line. Angle A
Can be between 3 ° and 12 °, and even between 3 ° and 5 °
It is preferable to set it in between.

The angle B between the centerline parallel to the bottom of the groove 26 and the plane containing the region 24 is preferably about 20 °. The angle C between the centerline parallel to the bottom of the groove 28 and the plane containing the region 14 is preferably about 16 °. The angle between the center lines is 135 ° -170 °, preferably 14 °
It is 0 ° to 150 °. From the periphery of the sloped parts 22 and 23 to the stepped part 31
Extend upward and reach the inner peripheral edge of the region 14.

The printed circuit board 12 carries supports 32, 33. The supports 32, 33 are formed with lips 36, 37 respectively and are provided with substantially cup-shaped recesses 34, 35 for engaging the lips 36, 37 with the catches 38, 39 of the substrate 3. As a result, the board 3 and the circuit board 12 are integrally locked. A recess 40 is formed on the inner edge 11 of the circuit board 12. On the lower surface of the substrate 3, there are hanging walls 41, 42, which have the same shape and dimensions as the peripheral shape of the recess 40.
43 is formed, which serves to seal the circuit board 12 and accommodate the pillar 8 described above.

When the board 3 and the circuit board 12 are locked to each other, the recess 34 becomes the groove 26.
Aligns and abuts end 27 of groove 26, and recess 35 aligns with groove 28 and abuts end 29 of groove 28. As shown in FIG. 1, an inner step portion 44 is formed in the recess 34, and a photodiode (not shown) is arranged at the bottom of the recess. The optical path of the photodiode runs through the biconvex lens 45 and along the centerline of the groove 26. A light emitting diode 46 is arranged in the recess 35, and its optical path is along the center line of the groove 28. The two center lines mentioned above coincide at point D, which is above the ridge 17 and lateral to the ridge 17. The diode 46 is preferably of the gallium alumina arsenide type, which emits at a shorter wavelength (880 mm) than the commonly used 950 mm wavelength.

The supports 32 and 33 carry a pair of pillars 47, 48 and 49, 50 through the slots 51 and 52 of the substrate 3, respectively. A thermistor 53 is provided across each pair of pillars and a thermistor coupling member 54 extends downwardly toward the circuit board 12 to retain the thermistor against the circuit board. The top of the thermistor is flush with the shoulder 16 of the upright wall 15
Is in contact with

As can be seen in FIG. 2, a plurality of inwardly inclined support members 55 extend radially inward from the upright wall 15.
A circumferential ridge 56 is formed on the substrate 3 between the support members 55. (However, the circumferential ridge 56 is not shown in FIG. 1).

A plate 57 having a recess 58 aligned with the recess 40 of the circuit board 12,
It contacts the circuit board 12 at several locations (not shown) on the periphery of the board. The board 57 is locked to the circuit board 12 and the board 3 by a plurality of arms 59 carried by the board and having bent ends 60 for engaging the board. Therefore substrate 3
The circuit board 12 and the board 57 can be combined and handled as a single unit.

The chamber 6 is covered with a cap 61. The cap 61 comprises a peripheral wall 62 having an outwardly facing ledge 63, the ledge 63
Receives the circumference of the net 5 by. Several rows of circumferential ridges are formed on the lower surface 64 of the cap 61, these ridges being surfaces 65a, 65b, 65c, 65d, 65e, defined by a radius centered on the optical center of the light emitting diode 46. Each has 65f. The angle of inclination between these surfaces and the bottom surface 64 of the cap is different. In order to accurately position the cap 61, the cap 61 is supported by a plurality of legs 66 arranged in axial symmetry, and the leg 66 has a reduced diameter portion 67 to be inserted into a hole (not shown) of the substrate 3. Has been formed.

The cover 4 has an upper portion 68 that abuts the upper surface 69 of the cap 61,
It has a hanging skirt portion 70 for locking the circumferential edge of the net 5 holding the peripheral wall 62 to the protrusion 63. On the outer peripheral edge of the upper portion 68, an extending portion 71 extending outward from the hanging skirt portion 70, a plurality of radial fins 72 at intervals, and a rib 73 connecting the upper portion 68 having a circumferential portion 74. And are provided. Each fin
Ribs 75 are formed at 72 to lock the outer peripheral edge of the net 5 to the shoulder portion 16. The cover 4 is secured to the substrate 3 by a series of scissors-fitting members 76 having an enlarged head 77 inserted in an opening 78 in the substrate 3. By the above engagement, the net 5 and the cap
61 and are locked to the substrate 3.

A plurality of locking members 79 are provided on the periphery of the plate 57,
The receiving member 80 of the main body 1 is rotationally moved and engaged. The recesses 40, 58 in the circuit board 12 and the board 57 house the pillars 8 and lock or unlock the board 57 relative to the body 1 by pivoting the body 1 and the rest of the detector relative to each other. At the same time, the connector 13 can be engaged or disengaged at the same time.

The circuit board 12 and the box 7 contain the necessary electrical connectors and circuit elements, and the box 7 contains the terminals (not shown) accessible through the body 1. Circuit board 12 and box 7 if necessary
In addition, the microcomputer and other circuit elements disclosed in the applicant's co-pending application U.S. Pat. No. 8,431,883 can be provided.

As is well known, the scattering of emitted light from the diode 6 by smoke particles in the chamber 6, in particular at the slope of the point D, is detected by the photodiode in the recess 34.
It is important to use a diode 46 made of gallium alumina arsenide, which has a shorter wavelength than the normal wavelength, because the relationship between scattering and wavelength depends on the inverse fourth power law. It is preferred to cooperate with the diode in the recess 34 in conjunction with a filter that passes the infrared band to remove ambient light levels entering the chamber 6. Light does not enter the room directly as it does directly into the diode, but rather enters at a low level due to many reflections.

An important feature of the present invention is to reduce the scattering and reflection of light from the diode 46 in the chamber 6 in the smoke-free state to a predetermined constant level. A given constant level allows for continuous or continuous monitoring of sensor operation.

Therefore, the inner surface of the chamber 6 is finished with a black texture to reduce the false reflected light. Pseudo-reflected light is further reduced by the provision of the step 31, the inner step 44, the circumferential ridge 56 and the surfaces 65a-65f.

As a result of many experiments, it has been found that the desired low scattering angle is 10 ° (when the ideal optical path meets at 170 °). In fact, it was found that a scattering angle of 45 ° or less is considerably superior to the conventional structure. Due to the various angles between these optical paths, the plane of the region 14 of the substrate 3, the offset position of the chordal ridges 17 and the angle A, a low scattering angle is obtained and the photodiode directly receives the light from the light emitting diode 46. Can be prevented. The grooves 21 reduce the pseudoscattering caused by small insects trapped in the center of the upper surface 18. If the grooves 21 were not provided, the small insects in the center of the upper surface 18 would scatter more than the small insects at the edges of the upper surface.

The thermistor 53 improves the overall sensitivity of the fire detector and increases the range of fire types that can be detected. The mesh 5 also serves as a heat collector for the thermistors connected in parallel. Since these thermistors are non-linear devices, they are dominated by thermistors under high temperature conditions.
Since the fin 72 does not extend over the annular gap between the rib 73 and the vertical skirt portion 70, the annular space 81 is exposed to the net 5. Therefore, the hot air can circulate in the annular space 81 and directly contact the net 5 over a wide area.

When the fire detector is installed on the ceiling surface 2 as shown in FIG. 3, the smoke carried by the low-speed airflow flows upward through the net 5 by convection. If the air velocity is high (0.1 m / s or more), most of the airflow flows along the ceiling surface.
In such a case, the airflow is extended by the extension portion 71 and the depending skirt portion 70.
It is turned by (Fig. 1) and passes through the net 5 at a right angle. The fins 72 and the ribs 73 assist the above-mentioned change. According to the invention, the smoke concentration in the sky 6 is higher than that in the air flow outside the chamber, even in the case of low velocity air flow.

Although the net 5 is provided in the above-mentioned embodiment, the net 5 can be omitted when the area which is not affected by the insect or other means for distinguishing the false judgment generated by the insect is provided.

Also, although described with respect to optical smoke sensors, the present invention can be utilized with any type of particle or gas detector.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an optical detector according to the present invention, FIG. 2 is a plan view showing a substrate of the fire detector of FIG. 2, and FIG. 3 is a side view of the fire detector attached to the ceiling. . 3 ... Substrate, 4 ... Casing, 5 ... Net, 6 ... Chamber,
14 ... peripheral region, 17 ... raised, 21 ... longitudinal groove, 34,35 ...
… Recesses, 46 …… light emitters, 53 …… thermal sensors, 72 …… fins, 75 …… ribs, 81 …… annular space.

Continuation of the front page (56) Reference JP-A-60-100022 (JP, A) JP-A-51-77386 (JP, A) JP-A-56-2538 (JP, A) Actual development Sho-60-148688 (JP , U) Actually open 60-10393 (JP, U) Actually open 58-76991 (JP, U) Actually public 52-46136 (JP, Y1)

Claims (8)

[Claims] 1. A fire detector arranged on an installation surface such as a ceiling surface (2), comprising a chamber (6) having a substrate (3) and opening to the outside, the substrate (3) The peripheral area (14) of the substrate is located on a single plane that is preferably parallel to the plane where the fire detector is installed, and inside the peripheral area (14) of the substrate (3) is a pair of slopes facing each other. The recesses (34, 35) are formed so that the recesses (34, 35) meet at a substantially central ridge (17) extending laterally across the substrate (3). And a light emitter (46) is attached to one end of the recess remote from the ridge (17) with an optical path directed along the recess, and a receiver is attached to the other. At the end of the recess of the recess away from the ridge (17), a fire detector mounted with opposite optical paths (30) along the recess. The two optical paths are formed at different angles (B, C) with respect to the single plane, so that the optical axes of the light emitter and the light receiver are substantially separated from the ridge (17). At a position (D) in the chamber (6) laterally spaced apart from each other at an angle of 170 ° to 135 °, and the two optical paths are parallel to a plane including the peripheral region (14). A fire detector characterized by being arranged at an angle (A) of 3 ° to 12 °. 2. The fire detector according to claim 1, wherein both optical axes meet at an angle (B, C) of 150 ° to 140 °. 3. The fire detector according to claim 1 or 2, wherein the angle (A) is 3 ° to 5 °. 4. A fire detector according to any one of claims 1 to 3 in which the ridge (17) is laterally offset from the center of the chamber (6). 5. The fire detector according to claim 4, wherein a longitudinal groove (21) is formed in the ridge (17). 6. The chamber (6) is open to the outside air only through a net (5) having a small mesh that does not allow insects to enter, and the net (5) is substantially flat and on the installation surface. And a portion of the fire detector casing (4) extends outwardly of the net (5) to carry smoke and move substantially parallel to the plane of the net (5). The fire detection according to any one of claims 1 to 5, wherein at least a part of the gas flow is formed so as to be deflected through the mesh in a direction perpendicular to the plane of the mesh. vessel. 7. A fire detector according to claim 6 including at least one thermal sensor (53) in contact with the mesh (5). 8. Inside the chamber (6), the reflection and scattering of light from the light emitter in the absence of smoke is reduced to a predetermined constant level so that a sensor allows for weekly or continuous monitoring. The fire detector according to any one of claims 1 to 7, which has a shape having a surface finish.