JP3017447B2 - Fire detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a system ceiling T
The present invention relates to a fire detector attached to an air-conditioning inlet such as a bar slit for detecting smoke caused by a fire.

[0002]

2. Description of the Related Art FIG. 12 shows a conventional fire detector installed in a T-bar slit on a system ceiling. In FIG. 12, a fire detector 102 is attached to a T-bar slit 100 formed as an air-conditioning suction port on the system ceiling by disposing a T-shaped angle member with an appropriate fitting. The fire detector 102 includes a detector main body 104 having a built-in smoke detector 108 and a smoke inlet 11.
It is composed of an outer cover 106 having an opening 0.

[0003] The smoke detector 108 of the sensor body 102 is, for example, a thin cylindrical body. A smoke inlet is formed around the smoke detector, and a light emitting element and a light receiving element are arranged inside thereof with their optical axes shifted. The light receiving element receives the scattered light when the light hits the particles to detect a fire. The sensing body 104 disposed above the ceiling is provided, for example, with an opening 112 communicating with the internal smoke detection unit 108 at the upper part, and forcibly creates the flow of air through the smoke detection unit 108 using the suction pressure of the air conditioner. ing.

[0004]

However, in a fire detector which uses the suction pressure of such an air conditioner to forcibly introduce and detect indoor smoke into the detector body,
When air-conditioning is stopped, forced introduction of smoke cannot be expected, and it takes a long time for smoke to flow in due to a fire, and there is a problem that fire detection is delayed.

[0005] When the air conditioning is stopped, there is a case where a reverse airflow blown into the room from the T-bar slit 100 due to the wind pressure of the outside air is generated.
There is a danger that it will not flow into the country and lead to unreported information. In order to solve the problem of unreported due to the backflow, the opening 11
If the number 2 is eliminated, there is a problem that the smoke cannot sufficiently flow into the smoke detection unit 108 because the smoke detection unit 108 is located far from the opening 110 of the outer cover 106 in the sensor main body 104 arranged behind the ceiling. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has a T-bar slit or the like capable of properly introducing indoor smoke and quickly detecting a fire without depending on the air-conditioning suction pressure. It is an object of the present invention to provide a fire detector attached to a vehicle.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to a fire detector for detecting smoke caused by a fire, which is attached to a suction port of an air conditioner which is opened in a slit shape on a system ceiling, and has a downward cover mounting port. The sensor body is located near the slit-shaped opening in the system ceiling and placed behind the ceiling, and the sensor is attached to the cover mounting opening of the sensor body so that it protrudes below the ceiling surface, and smoke from all directions around An outer cover with a smoke introduction opening formed so as to allow air to flow into the sensor body so that a part is located at a position protruding from the ceiling inside the outer cover, and smoke is omnidirectional around the outer cover. A smoke detection unit having a smoke inlet corresponding to each of the inlets.

[0008] Since a part of the smoke detector provided on the sensor main body side is located inside the outer cover projecting from the ceiling into the room, the airflow along the ceiling surface passes through the outer cover. The fire is directly introduced into the smoke detection section, enabling quick fire detection without depending on the air-conditioning suction pressure. In addition, the outer cover and the smoke detector located in the outer cover have a horizontal rotation along the ceiling surface,
Uniform smoke inflow characteristics that enable its introduction and discharge are obtained, and are not restricted by the direction of air flow.

The smoke detector is, for example, a thin cylindrical body,
A part of the cylindrical body is attached to the sensor body so that it protrudes from the cover mounting port in a half-moon shape and is located inside the outer cover, and it is located inside the outer cover to obtain uniform smoke inflow characteristics to airflow from all directions. The smoke inlets are independently formed on the front, rear, left and right sides of the cylindrical body. Further, a partition wall is formed in the outer cover to independently partition the smoke inlet of the cylindrical body located in the outer cover.

In order to partially utilize the forced introduction by the air-conditioning suction pressure, a relatively small opening communicating with the smoke detector is provided on the side of the sensor body on the back side of the system ceiling,
The opening allows the air flow to be derived from the smoke detector by the suction pressure of the air conditioner. As an opening hole on the side surface of the sensor main body, a mounting hole of a fitting piece for a mounting bracket for mounting the sensor main body in a slit-shaped opening of the system ceiling is used. For this reason, the opening area for forced introduction using the air-conditioning suction pressure is considerably limited. For this reason, even if the air conditioning is stopped, the smoke inflow characteristic to the smoke detection unit does not decrease so much, and conversely, the backflow due to the wind pressure of the outside air can be suppressed,
The effect of stopping air conditioning is minimized.

[0011]

FIG. 1A is a front view of a fire detector according to the present invention, FIG. 1B is a side view, and FIG. 1C is a plan view seen from below. 1 (A) to 1 (C), reference numeral 2 denotes a sensor main body of the fire detector 1. A cover mounting port 2a is opened at a lower end of the sensor main body 2, and an outer cover 3 is provided at the cover mounting port 2a. Is detachably attached. That is, a pair of protrusions 2b are formed on the lower side surface of the sensor main body 2,
A pair of engagement pieces formed on the upper end of the outer cover 3 are engaged with the engagement portions formed on the rear side of the projections 2b.

The outer cover 3 is formed with four smoke inlets 4 so that smoke from all directions can flow into the outer cover 3, and an insect screen 4 a for preventing insects from entering these smoke inlets 4. Are attached. The smoke inlet 4 has four smoke inlets, a smoke inlet opening left and front, a smoke inlet opening left and rear, a smoke inlet opening right and front, and a smoke inlet opening right and rear. It consists of an inlet.

An opening 6 is formed in the side surface of the sensor main body 2 and communicates with an internal smoke detecting section. The opening 6 allows the air flow to be derived from the smoke detecting section by the suction pressure of the air conditioner. A locking piece 5 that is locked to a mounting bracket for mounting the sensor body 2 is incorporated in the opening 6. That is, as the opening hole 6, a mounting hole of the locking piece 5 that is locked to the mounting bracket for mounting the sensor main body 2 is used. For this reason, the opening area for forced introduction using the air-conditioning suction pressure is limited.

FIG. 2 is an explanatory view of the mounted state of the fire detector of the present invention. In FIG. 2, T-bar members 7a and 7b are arranged on the ceiling with a predetermined slit width, each supporting a ceiling board 10, and a T-bar slit 7c serving as an air-conditioning suction port is formed therebetween. The detector main body 2 of the fire detector 1 is mounted on the T-bar slit 7c by mounting brackets 8,9.

The sensor body 2 is mounted above the ceiling board 10 so that the cover mounting opening 2a is located near the opening of the T-bar slit 7c. That is, the mounting bracket 8 is located on the underside of the ceiling, and the mounting bracket 9 is located on the outside of the ceiling.
Is inserted into the mounting brackets 8 and 9, and at this time, the locking piece 5 of the sensor main body 2 is locked in the opening 9 a of the lower mounting bracket 9. A screw 11 is inserted into the lower mounting bracket 8, and the screw 1
The T-bars 7a and 7b are sandwiched between the edges of the lower ends of both sides of the mounting brackets 8 and 9 by being screwed into the upper mounting bracket 9 so as to be mounted and fixed.

FIG. 3 is an exploded view of the sensor body 2, FIG. 3A shows one body cover of the sensor body 2, FIG. 3B shows a printed circuit board, and FIG. Indicates the other body cover of the sensor body 2. In FIG. 3A,
One main body cover 11 of the sensor main body 2 has a partition wall 17 composed of a curved portion and an L-shaped portion formed slightly below the inner central portion. A circuit storage portion 11a for storing circuit components mounted on a printed circuit board is defined above the partition wall 17, and a smoke detection portion storage portion 11b for storing a smoke detection portion is defined below the partition 17.
Is defined.

A unit housing portion 11c for housing the insertion terminal unit mounted on the printed circuit board is formed on the upper portion of the main body cover 11, and boss portions 18a are formed on both sides of the unit housing portion 11c. Is a screw hole 18b
Are drilled. At the lower end of the main body cover 11, a cover mounting port 2a for detachably mounting the outer cover 3 is formed.

A boss 18b having a screw hole 18a formed therein is formed on both sides of the partition wall 17, and a holding portion 11d for holding the plate-like portion 5a of the locking piece 5 integrally with the boss 18b is formed. . The locking piece 5 is made of a plate-like spring member.
The plate-like portion 5a is formed with a slit hole 1 formed in the holding portion 11d.
The bent convex portion 5b of the locking piece, which is held by 1c and protrudes from the slit hole 11c, protrudes outward from the opening 6 formed on the side surface of the sensor main body 2.

An insertion terminal unit 15 is mounted on the printed circuit board 13 shown in FIG. 3B so as to protrude therefrom, and various circuit components (not shown) are mounted on the printed circuit board 13 below the insertion terminal unit 15. Is done. Plug-in terminal unit 15
Screw holes 13a are formed in the printed circuit boards 13 on both sides of the printed circuit board. A notch 14 is provided on the lower side of the printed circuit board 13.
The smoke detection unit 14 which is formed of a thin cylindrical body having a and having a protruding introduction portion 16 protruding downward is mounted. The smoke detection unit 14 projects a part of the cylindrical body and projects the introduction unit 16 in a half-moon shape in a state where the smoke detection unit 14 is mounted on the lower side of the printed circuit board 13. It is positioned inside the outer cover 3 in a standing state, and the smoke introduced from the smoke inlet 4 is introduced into the smoke detector 14. The smoke detector 14 has a screw hole 14 through the printed circuit board 13.
b is formed.

FIG. 3C shows the other main body cover 12 of the sensor main body 2. At the upper end of the main body cover 12, a boss 19b having a pair of screw holes 19a is formed.
Further, a boss 19b having a screw through hole 19a protruding therefrom is formed below the center. A notch 12 a is formed below the body cover 12, and the notch 12 a forms a part of the opening 6.

A cover mounting port 2a is formed at the lower end of the main body cover 12. The printed circuit board 13 is housed in the main body cover 12, and the screw holes 1 of the printed circuit board 13 are inserted.
The screw holes 18a of the body cover 11 are aligned with the screw holes 18a, 13a, 14a,
The sensor main body 2 is assembled by screwing a screw into a.

FIG. 4 is an explanatory view of the internal structure of the main body cover 12 with the main body cover 11 removed. In FIG. 4, a printed circuit board 13 on which an insertion terminal unit 15 and a smoke detection unit 14 are mounted is housed in a main body cover 12. The outer cover 3 is attached to the cover attachment opening 2 a of the main body cover 12 in a state where the outer cover 3 projects below the ceiling surface 50. Note that the outer cover 3 is an aa cross section slightly deviated from the center of FIG.

The smoke detecting section 14 has a projecting introduction section 16 which is a part thereof from the cover mounting opening 2a and projects downward. That is, the smoke detection unit 14 is mounted on the sensor main body 2 so that the protrusion introduction unit 16 is located at a position inside the outer cover 4 protruding from the ceiling surface 50, and the smoke detection unit 14 is uniform with respect to the airflow from all directions of the outer cover 3. In order to obtain smoke inflow characteristics, the smoke introduction ports 27 and 30 are separately formed in the front and rear and left and right of the projecting introduction portion 16 located in the outer cover 3.

The outer cover 3 has an outer cover 3 inside.
A partition wall 31 that independently partitions the smoke introduction ports 27 and 30 of the protruding introduction section 16 of the smoke detection section 14 located inside is formed. Therefore, the smoke introduced from the front side or the rear side of the outer cover 3 is guided to the inside of the smoke detection unit 14 by the partition wall 31 without passing through the rear side or the front side as it is.

For this reason, a uniform smoke characteristic that enables the introduction and discharge of air from the outer cover 3 to the internal smoke detector 14 with respect to air currents from all directions in front, rear, left, and right directions around the ceiling surface is obtained. And is not restricted by the direction of airflow.
FIGS. 5A, 5B, and 5C are explanatory diagrams of the smoke detector 14 mounted on the printed circuit board 13. FIG.

In FIG. 5A, reference numeral 22 denotes the smoke detector 14.
The base 22 is fixed to the printed circuit board 13. The light emitting element 20 and the light receiving element 2
1 are arranged with their optical axes shifted from each other, and scattered light generated when light strikes smoke particles entering the smoke detection space 25 is received by the light receiving element 21.
Receive the light and detect the fire. Base 22
The light-shielding plate 22a provided on the light-receiving element 21 regulates light from the light-emitting element 20 so that light does not directly enter the light-receiving element 21.

The base 22 has three engaging portions 22 in the circumferential direction.
The labyrinth cover 24 is mounted on the base 22 by turning the locking pieces 24a formed on the labyrinth cover 24 into these engaging portions 22b by turning them. The state in which the labyrinth cover 24 is attached to the base 22 is shown in FIGS. 5A and 5B, and the protrusion introduction part 16 of the smoke detector 14 protrudes downward from the base 22.

FIG. 5C shows the labyrinth cover 24. In the circumferential direction of the labyrinth cover 24, locking pieces 24a for locking to the engaging portions 22b of the base 22 are formed at three places. The center of the labyrinth cover 24 is a smoke detection space 25
The smoke detection space 24 is surrounded by a plurality of labyrinths 26. FIG. 6 is a sectional view taken along line AA of FIG.

In FIG. 6, the engaging portion 22b of the base 22
The locking piece 24a of the labyrinth cover 24 is locked to
A labyrinth cover 24 is mounted on the base 22.
The light emitting element 20 is attached to the base 22, and the light emitting element 20 emits light to the smoke detection space 25. Also, the base 22
The light receiving element 21 is attached to the, and when smoke is introduced into the smoke detection space 25 and illuminates the smoke particles, scattered light is generated. The scattered light is received by the light receiving element 21 and a fire is detected.

FIG. 7A is a sectional view taken along the line BB of FIG.
FIG. 7B is a cross-sectional view taken along line CC of FIG. 5B. FIG.
In (A), a plurality of smoke outlets 28 a to 28 e are formed on the outer periphery of the upper smoke detection unit 24 except for the protrusion introduction unit 16, and these smoke outlets 28 a to 28 e are connected to the protrusion introduction unit 16.
The smoke introduced into the smoke detection space 25 from the side is discharged to the outside.
In addition, the labyrinths 26a and 26b allow the smoke discharge space 3
The smoke entering the smoke discharge spaces 32a and 32b is discharged from the smoke discharge openings 28a and 28b.

The projecting introduction section 16 which is a part of the smoke detection section 24
A plurality of smoke inlets 27a to 27c are formed on the outer periphery of the outer cover 3, and these smoke inlets 27a to 27c introduce smoke from the left and right directions on the paper surface of the outer cover 3. Smoke inlet 2
The smoke introduced from 7a to 27c is a labyrinth 26c to
The air is introduced into the smoke detection space 25 through the smoke inlets 30a to 30c partitioned by 26e.

As shown in FIG. 7B, the projecting introduction portion 16
Is formed with a partition wall 29 in the left-right direction orthogonal to the paper surface. Therefore, the smoke inlets 27a to 27c, 30a to
Numeral 30 is divided into two parts. For this reason, the smoke introduced from the front and rear into the smoke inlets 30a to 30c is guided from the partition wall 29 to the smoke detection space 25, and then discharged from the opposite side.

Next, the operation will be described. FIG. 8 is an explanatory diagram of the smoke inflow characteristic during the air conditioning operation. Arrow A during smoke operation
Let it flow from left to right like Smoke flowing from left to right as indicated by arrow A indicates the outer cover 3 as indicated by arrow B.
, The smoke inlet 27 c formed on the outer periphery of the protruding inlet 16 of the smoke detector 14, and the labyrinth 26.
The smoke enters the smoke detector 14 via the smoke inlet 30c formed by e and the like, and is introduced into the smoke detection space 25.

A part of the smoke introduced into the smoke detector 14 receives the suction pressure from the air conditioning in the ceiling as indicated by an arrow E,
Smoke discharge units 28e and 28f formed on the outer periphery of the smoke detection unit 14.
From the opening 33, and is discharged from the opening hole 6 to the space above the ceiling as indicated by an arrow D1. On the other hand, the smoke introduced into the smoke detection space 25 is, as indicated by an arrow C, the smoke discharge space 32b and the smoke detection unit 1.
4 enters the outer cover 3 through the space 33b from the smoke outlet 28a, and is discharged to the outside from the smoke inlet 4 on the right side of the outer cover 3.

Further, the smoke discharged from the smoke discharge space 32a and the smoke discharge port 28b of the smoke detector 14 into the space 33b is subjected to the air-conditioning suction pressure indicated by an arrow E, and is passed from the opening 6 to the space above the ceiling as indicated by an arrow D2. Is discharged. The smoke entering the space 33b is
Since there is the partition wall 17, it does not flow above the sensor main body 2. FIG. 9 is an explanatory diagram of smoke inflow characteristics when air conditioning is stopped. When the air-conditioning is stopped, as in FIG. 8, when the smoke flows from left to right, the smoke enters the smoke inlet 4 on the left side of the outer cover 3 as shown by the arrow A, and the projecting inlet of the smoke detector 14. Through the smoke inlet 27c formed on the outer periphery of the cylinder 16 and the smoke inlet 30c partitioned by the labyrinth 26e, the gas enters the inside of the smoke detector 14 as indicated by an arrow B1, and is introduced into the smoke detection space 25. Further, as indicated by an arrow B2, the smoke that has entered the smoke inlet 4 on the left side of the outer cover 3 is released from the smoke inlet 27b on the outer periphery of the protruding inlet 16.
Through the smoke inlet 30b.

The smoke introduced into the smoke detection space 25 is indicated by an arrow C1.
As described above, the air is discharged to the outside from the smoke inlet 4 on the left side of the outer cover 3 via the smoke inlet 30a and the smoke inlet 27a.
Further, the smoke introduced into the smoke detection space 25 moves from the smoke detection space 25 to the smoke discharge space 32b and the smoke discharge port 28 as indicated by an arrow C2.
Then, the air enters the space 33b through the a, and is also discharged to the outside through the smoke inlet 4 on the right side of the outer cover 3.

At this time, since the air conditioning is stopped, the suction pressure by the air conditioning does not act on the space 33b through the opening hole 6, and the smoke entering the space 33b is not exhausted from the opening hole 6 to the outside. It is discharged to the outside through the smoke inlet 4 on the right side of the outer cover 3. Since the opening hole 6 uses the mounting hole of the locking piece 5 which is locked to the mounting brackets 8 and 9 attached to the sensor body 3, the opening area for forced introduction using the air-conditioning suction pressure is limited. Have been.

For this reason, even if the air conditioning is stopped, the smoke detector 1
The smoke inflow characteristics for 4 are not significantly reduced. As described above, since the protruding introduction portion 16 of the smoke detector 14 is located inside the outer cover 3 below the ceiling surface, the smoke along the ceiling surface is directly passed through the outer cover 3 to the smoke detector. 14, it is possible to quickly detect a fire without the air-conditioning suction pressure for stopping the air-conditioning.

FIG. 10 is an explanatory diagram of the smoke inflow characteristic at the time of backflow blowing due to the stoppage of air conditioning. In FIG. 10, it is assumed that smoke flows from left to right similarly to FIGS. As shown by arrow A, the smoke
From the smoke inlet 4 on the left side of FIG.
Arrow B through the smoke inlet 27c and the smoke inlet 30c of No. 6
As shown in FIG.
Will be introduced.

As shown by the arrow B2, the smoke entering from the smoke inlet 4 on the left side of the outer cover 3 is introduced into the smoke detection space 25 via the smoke inlet 27b and the smoke inlet 30b of the protruding inlet 16. . In this case, the outlet pressure F of the backflow caused by the stop of the air conditioning
Can act on the space 33a as shown by the arrow G1 through the opening hole 6, since the opening area is limited by the incorporation of the locking piece 5, the backflow can be suppressed.

Therefore, even if the air flows in the reverse direction due to the stoppage of the air conditioning, the smoke is introduced into the smoke detection space 25 as indicated by arrows B1 and B2. The smoke introduced into the smoke detection space 25
As indicated by arrow C1, the smoke inlet 30a and the smoke inlet 27
The air is discharged to the outside through the smoke inlet 4 on the right side of the outer cover 3 through the line a. Further, as indicated by an arrow C2, the smoke introduced into the smoke detection space 25 is discharged from the space 33b through the smoke discharge space 32b and the smoke discharge opening 28a to the outside from the smoke inlet 4 on the right side of the outer cover 3.

As described above, even if there is a blow-off pressure F due to the backflow, the backflow can be suppressed because the opening area of the opening hole 6 is limited, and the influence of stopping the air conditioning can be minimized. . FIG. 11 is a diagram illustrating smoke inflow characteristics in the front-rear direction. In FIG. 11, it is assumed that the smoke flows from the front side to the rear side of the outer cover 3 as indicated by an arrow H. At this time, the smoke flows in from the smoke inlet 4 of the outer cover 3 as shown by the arrow I. Inside the outer cover 4 there is a partition wall 29 that partitions the front and rear.
Are located, and the smoke inlet 3 is separated by labyrinths 26c to 26e.
0a to 30c, smoke detection space 25
Will be guided to. The smoke introduced into the smoke detection space 25 is indicated by an arrow J.
, The smoke inlets 30a to 30a on the opposite side of the partition habit 2
c, and is discharged to the outside through the smoke inlet 4 of the outer cover 3.

As is apparent from the operation shown in FIGS. 8 to 11, the position of the smoke inside the outer cover 3 with respect to the smoke from all directions from front to rear and right and left, which is horizontal along the ceiling surface with respect to the outer cover 3. Uniform smoke inflow characteristics that enable smooth introduction and discharge of smoke from the protruding introduction portion 16 of the smoke detection portion 14 to the smoke detection portion are obtained, and are not restricted by the direction of smoke due to airflow.

[0044]

As described above, according to the present invention, the smoke detector is mounted on the sensor body such that a part of the smoke detector is located at a position protruding from the ceiling surface in the outer cover. Then, since the airflow along the ceiling surface is directly introduced into the smoke detection unit via the outer cover, quick fire detection can be performed without depending on the air-conditioning suction pressure.

[Brief description of the drawings]

FIG. 1 is a three side view of an embodiment of a fire detector of the present invention.

FIG. 2 is an explanatory view of a mounting state of a fire detector according to the present invention.

FIG. 3 is an exploded view of a cover and an internal printed circuit board of the fire detector according to the present invention.

FIG. 4 is an explanatory view of an internal structure in which one of the covers of FIG. 1 is removed.

FIG. 5 is an explanatory diagram of a smoke detector provided on the printed circuit board of FIG. 3;

FIG. 6 is a sectional view taken along line AA of FIG. 5;

FIG. 7 is a sectional view taken along line BB and CC of FIG. 5;

FIG. 8 is an explanatory diagram of smoke inflow characteristics during air-conditioning operation.

FIG. 9 is an explanatory diagram of smoke inflow characteristics when air conditioning is stopped.

FIG. 10 is an explanatory diagram of smoke inflow characteristics at the time of backflow blowout due to the stoppage of air conditioning.

FIG. 11 is an explanatory diagram of smoke inflow characteristics in the front-rear direction.

FIG. 12 is a schematic explanatory view of a related art.

[Explanation of Signs] 2: Sensor main body 2a: Cover mounting port 3: Outer cover 4, 27, 30: Smoke inlet 5: Locking piece 6: Opening hole 7c: T-bar slit 8, 9: Mounting bracket 10: Ceiling board 14: Smoke detection unit 16: Projection introduction unit 31: Partition wall

Claims (5)

(57) [Claims] 1. A fire detector for detecting smoke caused by a fire, which is attached to a suction opening of an air conditioner opened in a slit shape on a system ceiling, wherein a downwardly facing cover mounting opening is provided with a slit-like opening in the system ceiling. A sensor body located near the ceiling and located in the vicinity, mounted on the cover mounting opening of the sensor body so as to protrude below the ceiling surface, so that smoke from all directions around the sensor can flow in. An outer cover forming a smoke inlet, incorporated into the sensor body such that a part thereof is located at a position protruding from a ceiling surface in the outer cover, and an omnidirectional smoke inlet around the outer cover. A smoke detector, comprising: a smoke detection section having a smoke inlet corresponding to each of the smoke detectors. 2. The fire detector according to claim 1, wherein the smoke detector is a thin cylindrical body, and a part of the cylindrical body protrudes from the cover mounting opening in a half-moon shape. The smoke detector is mounted on the sensor main body so as to be positioned inside, and the smoke inlets are independently formed at front, rear, left and right of the cylindrical body positioned inside the outer cover. 3. The fire detector according to claim 2, wherein a partition wall is formed in the outer cover to independently partition the smoke inlet of the cylindrical body located in the outer cover. And fire detector. 4. The fire detector according to claim 1, wherein the sensor main body further has an opening hole communicating with the smoke detector on a side surface of the sensor main body which is a rear surface side of the system ceiling. A fire detector, wherein the opening allows the airflow from the smoke detector to be derived from the suction pressure of the air conditioner. 5. The fire detector according to claim 1, wherein the opening on the side surface of the sensor main body is a hole into which a locking piece is attached to a mounting bracket for mounting the sensor main body on a slit-like opening of the system ceiling. A fire detector characterized by being.