JP2023175025A - Sensor and fire alarm system - Google Patents

Abstract

To improve smoke inflow property with respect to a smoke detection chamber.SOLUTION: A sensor 1 includes a smoke detection chamber 4 and at least one of airflow control walls 8. The smoke detection chamber 4 includes inflow openings 40 from which smoke flows in. The airflow control walls 8 are arranged in the periphery of the smoke detection chamber 4. The airflow control wall 8 controls an airflow so as to reduce variations of smoke inflow property with respect to the smoke detection chamber 4 in a circumferential direction A3 of the smoke detection chamber 4.SELECTED DRAWING: Figure 5

Description

The present disclosure generally relates to a sensor and a fire alarm system, and more particularly relates to a sensor that detects smoke generated by, for example, a fire, and a fire alarm system including the sensor.

Patent Document 1 discloses a combined heat and smoke sensor. This sensor includes a heat sensing means that senses heat, and a smoke sensing section (smoke detection chamber) that senses smoke that has flowed into the dark box. The heat sensing means includes a lead wire connected to the circuit board and protruding upward from the circuit board, and a heat sensitive element such as a thermistor provided at the upper end of the lead wire. Further, the smoke detection section is composed of a dark box, and a light emitting means and a light receiving means arranged inside the dark box, and detects scattered light when the light emitted from the light emitting means is scattered by smoke flowing into the dark box. Smoke is detected by the light receiving means receiving light.

Japanese Patent Application Publication No. 2012-14330

By the way, there may be a region on the peripheral wall of the smoke detection chamber where no smoke inflow port is formed and it is difficult for smoke to flow into the smoke detection chamber. Such areas can obstruct the flow path of smoke toward the interior of the smoke detection chamber.

The present disclosure has been made in view of the above reasons, and an object of the present disclosure is to provide a sensor and a fire alarm system that can improve smoke inflow into a smoke detection chamber.

A sensor of one aspect of the present disclosure includes a cover, a smoke detection chamber, and at least one airflow control wall. The smoke detection chamber is housed in the cover and has an inlet through which smoke flows. The airflow control wall is arranged around the smoke detection chamber in a manner extending from the smoke detection chamber side toward the peripheral wall side of the cover.
A fire alarm system according to one aspect of the present disclosure includes the above-mentioned sensor and a receiver that communicates with the sensor.

According to the present disclosure, there is an advantage that the smoke inflow into the smoke detection chamber can be improved.

FIG. 1 is a cross-sectional view of a sensor according to one embodiment. FIG. 2 is an external perspective view of the same sensor. FIG. 3 is an exploded perspective view of the sensor seen from above. FIG. 4 is an exploded perspective view of the sensor seen from below. FIG. 5 is a perspective view of the same sensor as seen from above, excluding a part of the upper cover. FIG. 6 is an exploded perspective view of the sensor of FIG. 5 with the cover of the smoke detection chamber removed. FIG. 7 is a block diagram of the same sensor. FIG. 8 is a perspective view of Modified Example 1 of the same sensor as seen from above, excluding a part of the upper cover. FIG. 9 is a sectional view of a main part of a second modification of the above sensor. FIG. 10 is a plan view of a modified example of the base in the above sensor.

(1) Overview Each figure described in the following embodiments is a schematic diagram, and the ratio of the size and thickness of each component in each figure does not necessarily reflect the actual size ratio. Not necessarily.

The sensor 1 according to the present embodiment is, for example, a fire sensor, and has a function of detecting (fire) smoke generated by a fire or the like. The sensor 1 is a photoelectric sensor. Although the following description assumes that the sensor 1 is a scattered light type sensor, the sensor 1 is not limited to the scattered light type and may be a transmitted light type sensor.

Further, in the following description, it is assumed that the sensor 1 is a so-called composite fire sensor that has a function of detecting heat generated by a fire or the like in addition to a function of detecting smoke. However, the sensor 1 does not need to have a heat detection function. As shown in FIG. 2, the sensor 1 is installed, for example, on a construction surface 100 (ceiling surface in the illustrated example) such as a ceiling surface or a wall surface of a building.

The sensor 1 according to this embodiment includes a smoke detection chamber 4 and a branch section 71, as shown in FIG.

The smoke detection chamber 4 has an inlet 40 through which smoke flows. The branch portion 71 is arranged around the smoke detection chamber 4 . The branching part 71 divides the space SP1 around the smoke detection chamber 4 into two in a separation direction A1 including a vertical direction A2 component, and divides the gas flow path 6 into two, an upper flow path 61 and a lower flow path 62. branch out.

The branching portion 71 is configured to cause smoke that has passed through the upper flow path 61 of the upper flow path 61 and the lower flow path 62 to flow into the smoke detection chamber 4 from the inflow port 40 .

According to this configuration, smoke particles that tend to rise easily pass through the upper channel 61, while steam particles having a larger mass than the smoke particles easily pass through the lower channel 62. In other words, there is a high possibility that only smoke will flow into the smoke detection chamber 4 from the inlet 40 due to the branch portion 71 . As a result, the sensor 1 has the advantage of reducing the possibility of false detection occurring.

By the way, in this embodiment, in addition to the smoke detection chamber 4, the sensor 1 further includes at least one (here, two as an example) airflow control walls 8 (see FIG. 5). The smoke detection chamber 4 has an inlet 40 through which smoke flows. An airflow control wall 8 is arranged around the smoke detection chamber 4 . The airflow control wall 8 controls the airflow so as to reduce variations in smoke inflow into the smoke detection chamber 4 in the circumferential direction A3 of the smoke detection chamber 4. Here, "the variation in smoke inflow property is small" means that smoke can enter the sensor 1 from any direction within 360 degrees around the sensor 1 (through the opening 510) when looking at the sensor 1 in the vertical direction. This means that even if smoke enters the smoke detection chamber 4, the difference in the amount flowing into the smoke detection chamber 4 is small.

According to this configuration, by controlling the airflow by the airflow control wall 8, variations in smoke inflow into the smoke detection chamber 4 are reduced. Therefore, the sensor 1 has the advantage of being able to improve smoke inflow into the smoke detection chamber 4.

(2) Details (2.1) Overall configuration The overall configuration of the sensor 1 according to this embodiment will be described in detail below. As described above, the sensor 1 is a composite fire sensor that detects smoke and heat.

In the following, the vertical direction of the sensor 1 will be defined and explained using the up and down arrows shown in FIG. 2, which shows the state in which the sensor 1 is installed on the construction surface 100 (ceiling surface). This arrow is merely shown for the purpose of assisting the explanation and has no substance. Further, this direction is not intended to limit the direction in which the sensor 1 is used.

The sensor 1 includes the smoke detection chamber 4 (smoke detection section) described above. The sensor 1 further includes a base 2, a housing 5, and a flow path forming member 7, as shown in FIGS. 1 and 3 to 6. The sensor 1 further includes a heat detection section 3, a control section 9, and a display section 10, as shown in FIG. The sensor 1 further includes a disk-shaped mounting base that is fixed to the construction surface 100 by screws or the like. The sensor 1 can be installed on the construction surface 100 by having a mounting portion provided on the upper surface side of the casing 5 removably attached to the mounting base.

The detector 1 further includes a communication unit 11 (see FIG. 7) that transmits a signal notifying the occurrence of a fire to an external alarm device, etc., and receives a signal from an alarm device, etc. when a fire is detected. ing.

The sensor 1 may be supplied with power by a commercial power supply, or may be supplied with power by a battery provided inside the housing 5.

(2.2) Housing The housing 5 accommodates the base 2, the heat detection section 3, the smoke detection chamber 4, the control section 9, the display section 10, the communication section 11, and other circuit modules, etc. . Furthermore, the housing 5 supports one surface of the guide portion of the display section 10 so as to be exposed to the outside.

The housing 5 is made of synthetic resin, for example, flame-retardant ABS resin. The housing 5 as a whole is formed into a cylindrical shape that is flat in the vertical direction. As shown in FIGS. 3 and 5, the casing 5 includes a cylindrical lower cover 51 (front cover) with one side (top surface in the illustrated example) open, and a substantially disc-shaped upper cover 52 (back cover). It has . The housing 5 is constructed by assembling the upper cover 52 to the lower cover 51 from one open side thereof. The upper cover 52 is arranged to cover the smoke detection chamber 4 from above. The lower cover 51 is arranged below the base 2.

The housing 5 also includes a flow path 6 provided in the internal space SP1 through which gas flows, and one or more (six in this case) openings 510 (horizontal holes) connecting the flow path 6 and the external space SP2. It has . Here, a plurality of openings 510 are provided in the lower cover 51. In other words, the lower cover 51 has an opening 510 that communicates the external space SP2 with the space SP1 around the smoke detection chamber 4.

Specifically, as shown in FIGS. 2 and 3, the lower cover 51 includes a flat cylindrical body 51A with both upper and lower ends open, and a disc-shaped base 51B located below the cylindrical body 51A. It is composed of a plurality of (for example, six) pillars 51C that connect the cylindrical body 51A and the base 51B. The cylindrical body 51A, the base 51B, and the six pillars 51C are integrally formed. The six pillars 51C are arranged at approximately equal intervals along the circumferential direction at the peripheral edge of the base 51B, and protrude from the peripheral edge toward the open lower edge of the cylindrical body 51A. The six pillars 51C maintain the distance between the cylindrical body 51A and the base 51B at a specified distance. The six openings 510 are arranged at approximately equal intervals along the circumferential direction (corresponding to the circumferential direction A4 of the sensor 1) on the circumferential wall of the lower cover 51 configured in this way.

Each opening 510 is a substantially rectangular through hole that penetrates the peripheral wall of the lower cover 51 in the radial direction, and serves as an opening that connects the flow path 6 and the external space SP2.

The base 51B has a positioning structure for positioning the base 2 on its upper surface. Here, a cylindrical portion 511 is provided as the positioning structure (see FIGS. 1 and 3). In other words, the sensor 1 of this embodiment further includes the cylindrical portion 511 arranged to cover the lower surface (second surface 22) of the base 2. The cylindrical portion 511 protrudes in a cylindrical shape from the upper surface of the base portion 51B. The upper end surface of the cylindrical portion 511 contacts the lower surface of the base 2.

The lower cover 51 has a pair of holes (not shown in FIG. 2) in the base 51B for exposing one surface (lower surface) of the guide portion of the display section 10 to the external space SP2. Therefore, the light emitted from the pair of light sources 10A (see FIG. 4) of the display section 10 is guided to the outside of the housing 5 through the pair of guide sections, respectively.

The upper cover 52 has a plurality of insertion holes into which a plurality of connection pieces of a mounting portion fixed to the base 2 are inserted. The plurality of connection pieces are electrically connected to a circuit module provided on the base 2. The plurality of connection pieces are inserted to such an extent that their tips sufficiently protrude from the back side of the upper cover 52. The plurality of connection pieces can be mechanically and electrically connected to contact portions of the mounting base fixed to the construction surface 100. In short, the mounting part is not only a mechanical connection to the mounting base, but also an electrical connection to the electric wires (power supply line and signal line) on the back side of the ceiling, and a stable connection of the base 2 to the upper cover 52. This part also serves as positioning.

Further, the upper cover 52 has an accommodation recess 521 (see FIG. 4) on one surface (lower surface) facing the base 2 for accommodating the upper part of the smoke detection chamber 4 mounted on the base 2. The housing recess 521 is formed by the entire center portion of the upper cover 52 protruding upward. The smoke detection chamber 4 is stably positioned by the accommodation recess 521.

Here, the sensor 1 further includes a pair of airflow control walls 8, as shown in FIG. Here, as an example, the airflow control wall 8 is formed as a part of the upper cover 52. The pair of airflow control walls 8 are provided outward from the accommodation recess 521 on one surface (lower surface) of the upper cover 52 that faces the base 2 . The pair of airflow control walls 8 are arranged around the smoke detection chamber 4 and control the airflow so as to reduce variations in smoke inflow into the smoke detection chamber 4 in the circumferential direction A3 of the smoke detection chamber 4. A detailed description of the airflow control wall 8 will be given later.

(2.3) Base The base 2 is configured such that the smoke detection chamber 4 is mounted thereon. Here, as an example, the base 2 is a circuit board. The base 2 is, for example, a single printed wiring board provided with conductor pattern wiring. As shown in FIGS. 3 and 4, the base 2 has a pair of engagement holes 27 passing through the base 2 in its thickness direction. The pair of engagement pieces 42 (see FIG. 4) provided on the body 4B of the smoke detection chamber 4 are inserted into and hooked into the pair of engagement holes 27, respectively, so that the smoke detection chamber 4 is connected to the second section of the base 2. It is attached to one surface 21 (upper surface). Note that the flow path forming member 7 is held in such a manner that it is sandwiched between the smoke detection chamber 4 and the base 2 from above and below.

Furthermore, in addition to the smoke detection chamber 4, the base 2 is equipped with a heat detection section 3, a control section 9, a display section 10, a communication section 11, and other circuit modules. Other circuit modules include a lighting circuit that lights up the light source 10A of the display unit 10 and the optical element 401 of the smoke detection chamber 4 (see FIGS. 6 and 7), and various circuits that use power supplied from a commercial power source, etc. Includes power supply circuits that generate operating power for the circuits.

As shown in FIGS. 3 and 4, the base 2 is formed into a substantially circular shape as a whole. In this embodiment, one or more (six in FIG. 5) heat detection elements 30 of the heat detection unit 3 are arranged on the outer peripheral portion 23 of the base 2. The six heat sensing elements 30 are surface mounted on the first surface 21 (upper surface) of the base 2. Here, as an example, the smoke detection chamber 4 is also arranged on the first surface 21 of the base 2. Hereinafter, the surface of the base 2 opposite to the first surface 21 may be referred to as the second surface 22 (lower surface). The light source 10A of the display unit 10 is mounted on the second surface 22 of the base 2, as shown in FIG.

Of the first surface 21 and the second surface 22, the first surface 21 corresponds to the surface closer to the construction surface 100. Therefore, it can be said that the heat detection element 30 and the smoke detection chamber 4 are both arranged on the surface of the base 2 that is closer to the construction surface 100.

The control unit 9 and a plurality of electronic components constituting the circuit module are mounted on the first surface 21 or the second surface 22 of the base 2. The control unit 9 and the plurality of electronic components constituting the circuit module do not need to be mounted only on the base 2; for example, another mounting board may be arranged around the base 2, and the electronic components constituting the circuit module may be mounted on the base 2. Some or all of them may be implemented.

The structure of the base 2 will be described in detail below. As shown in FIG. 5, the base 2 includes a circular main body 20 (the part inside the dashed line) and a plurality of circular main body parts 20 (in the illustrated example) extending in a direction away from the center of the main body 20 at the edge of the main body 20. It has a total of 12 extension parts. The smoke detection chamber 4 is arranged at the center of the upper surface of the main body 20.

The twelve extending portions are composed of six protruding edges 25 and six tongues 26. The outer peripheral portion 23 of the base 2 described above is a portion corresponding to the six protruding edges 25 and the six tongue portions 26.

Each tongue portion 26 is a portion where a corresponding one of the six heat sensing elements 30 is mounted. Each tongue portion 26 has an upper surface and a lower surface that are flush with and continuous with the upper surface and lower surface of the main body portion 20, respectively. Each tongue portion 26 projects from the main body portion 20 in the shape of an elongated strip when viewed in the vertical direction, and its tip portion is formed in a semicircular shape. The six tongue parts 26 are arranged at equal intervals along the circumferential direction of the main body part 20 so as to divide the outer peripheral part 23 of the base 2 into approximately six equal parts. Each heat sensing element 30 is mounted near the tip on the upper surface of the corresponding tongue portion 26 . The tongue portion 26 has a through hole 260 having a rectangular opening in a region inside the heat sensing element 30 . By providing the through holes 260 near each heat detection element 30, the area occupied by the base 2 around the heat detection element 30 can be reduced. As a result, the heat in the heat detection element 30 is transmitted through the base 2 and becomes lower, or the heat generated by other circuit components mounted on the main body 20 affects the heat detection element 30. Possibility can be reduced. That is, the through holes 260 improve thermal insulation. The opening area of the through hole 260 is desirably larger than the surface area of the heat sensing element 30 (for example, the surface area viewed from above the base 2).

Each protruding edge 25 has an upper surface and a lower surface that are flush with and continuous with the upper surface and lower surface of the main body 20, respectively. Each of the protruding edges 25 is in the form of a strip, curved along an arc with the central axis of the main body 20 as the center of the circle, when viewed along the up-down direction. The six protruding edges 25 are lined up along the circumferential direction of the main body 20. A corresponding one of the six tongues 26 is arranged between two adjacent protruding edges 25. In other words, the six tongue portions 26 and the six protruding edges 25 are alternately arranged one by one along the circumferential direction of the main body portion 20 .

Each protruding edge 25 of this embodiment is configured to protrude outward from the cylindrical portion 511, as shown in FIG. In other words, when viewed along the vertical direction, the projected area of the main body portion 20 is approximately the same as the cylindrical portion 511, and the six protruding edges 25 protrude from the cylindrical portion 511. Note that the amount of protrusion of the tongue portion 26 with respect to the main body portion 20 is slightly larger than the amount of protrusion of the protruding edge portion 25.

Incidentally, the outer circumferential portion 23 of the base 2 has a recess 24 (see FIG. 5) that is recessed inward in a peripheral area where the heat sensing element 30 is arranged. Here, a total of 12 recesses 24 are provided so that a pair of recesses 24 corresponds to each of the six tongues 26. Specifically, a pair of recesses 24 are formed on both sides in the circumferential direction of the main body 20 of each tongue 26 on which the heat sensing element 30 is mounted.

Therefore, each tongue portion 26 is arranged between two adjacent protruding edges 25 so as to leave a gap between each of the two protruding edges 25 . Therefore, the hot air caused by the fire can be efficiently guided to the heat detection element 30 on the tongue 26 by the recess 24. That is, heat flow properties are improved. In addition, the heat in the heat detection element 30 may be transmitted through the base 2 and the heat generated in other circuit components on the main body 20 may be transferred to the heat detection element 30 on the tongue part 26 via the protruding edge 25. This can reduce the possibility of adverse effects.

As described above, the base 2 of this embodiment has, for example, a six-fold symmetrical shape that becomes symmetrical by rotating 60 degrees around its center.

(2.4) Heat Detection Unit and Smoke Detection Unit As described above, the heat detection unit 3 has six heat detection elements 30 mounted on the first surface 21 of the base 2 (in FIG. 7, one (only one shown). The number of heat detection elements 30 is not particularly limited, and may be one, but preferably at least two or more. The heat detection element 30 is a chip thermistor that detects the heat of the gas flowing in from the opening 510, and is surface mounted on the base 2. Each heat sensing element 30 is arranged to face one different opening 510.

The heat detection section 3 is electrically connected to the control section 9 via pattern wiring formed on the base 2 or the like. Each heat detection element 30 outputs an electric signal (detection signal) to the control unit 9. In other words, the control unit 9 monitors the resistance value of each heat detection element 30, which can change depending on the temperature rise, through the electrical signal output from each heat detection element 30.

In addition to the heat detection element 30, the heat detection unit 3 may further include an amplification circuit that amplifies the electrical signal from the heat detection element 30, a conversion circuit that performs analog-to-digital conversion, or the like, or the amplification and conversion may be performed. , may be performed on the circuit module side.

The smoke detection chamber 4 is arranged in the center of the internal space of the housing 5 and is configured to detect smoke. Specifically, the smoke detection chamber 4 is arranged on the upper surface of the main body part 20 of the base 2, and the upper part thereof is housed in the accommodation recess 521 of the upper cover 52. The smoke detection chamber 4 is, for example, a photoelectric sensor that detects smoke, particularly a scattered light sensor.

As shown in FIGS. 6 and 7, the smoke detection chamber 4 includes an optical element 401 that emits light, a light receiving element 402 that receives the light emitted from the optical element 401, and a labyrinth part 403. There is. The optical element 401 is, for example, an LED (Light Emitting Diode). The light receiving element 402 is, for example, a photodiode. The labyrinth portion 403 is formed inside a housing having a flat, substantially cylindrical outer contour.

The housing of the smoke detection chamber 4 is constructed by assembling a cover 4A and a body 4B. As shown in FIG. 6, the cover 4A has a flat, substantially cylindrical outer shell with an open bottom surface. The cover 4A has a plurality of inlets 40 on its outer peripheral surface that allow gas to flow into the labyrinth portion 403. Fire smoke flows into the labyrinth part 403 from the inlet 40. Each inlet 40 has a substantially rectangular opening when viewed from the front. The plurality of inflow ports 40 are arranged side by side along the circumferential direction A3 of the smoke detection chamber 4. In addition, in this embodiment, the circumferential direction A3 of the smoke detection chamber 4 coincides with the circumferential direction A4 of the sensor 1.

The body 4B is formed in a substantially disk shape, and has a structure on its upper surface that suppresses external light from entering the body, and a structure that holds the optical element 401 and the light receiving element 402. The body 4B also has a pair of engagement pieces 42 (see FIG. 4) that protrude downward from its lower edge. The pair of engagement pieces 42 are inserted into the pair of insertion holes 74 of the flow path forming member 7, and further inserted and hooked into the pair of engagement holes 27 of the base 2, so that the smoke detection chamber 4 It is attached to the base 2 in such a manner that the flow path forming member 7 is sandwiched between the flow path forming member 7 and the base 2.

The optical element 401 and the light receiving element 402 are arranged in the labyrinth portion 403 so as not to face each other. In other words, the light receiving surface of the light receiving element 402 is arranged so as to be off the optical axis of the light irradiated by the optical element 401.

When a fire or the like occurs, fire smoke enters the housing 5 through the opening 510 of the housing 5 and can be further introduced into the labyrinth portion 403 through the inlet 40. When there is no smoke within the labyrinth portion 403, the irradiated light from the optical element 401 hardly reaches the light receiving surface of the light receiving element 402. On the other hand, if smoke exists within the labyrinth portion 403, the light emitted from the optical element 401 is scattered by the smoke, and a portion of the scattered light reaches the light receiving surface of the light receiving element 402. That is, in the smoke detection chamber 4, the light receiving element 402 receives the irradiated light from the optical element 401 that is scattered by smoke.

The light receiving element 402 of the smoke detection chamber 4 is electrically connected to the control section 9. The smoke detection chamber 4 transmits to the control unit 9 an electric signal (detection signal) indicating a voltage level according to the amount of light received by the light receiving element 402. The control unit 9 converts the light intensity of the detection signal received from the smoke detection chamber 4 into smoke density and determines whether there is a fire. The control unit 9 may use the light amount as it is for threshold determination. The smoke detection chamber 4 may convert the amount of light received by the light receiving element 402 into smoke density, and then transmit a detection signal indicating a voltage level according to the smoke density to the control unit 9.

The smoke detection chamber 4 may further include an amplification circuit that amplifies the electrical signal from the light receiving element 402 and a conversion circuit that converts analog to digital, or the amplification and conversion may be performed on the circuit module side. Good too. Further, the number of optical elements 401 for smoke detection is not limited to one, and may be plural.

(2.5) Display section The display section 10 has a pair of light sources 10A and a pair of guide sections. Each light source 10A is configured, for example, as a packaged LED in which at least one LED chip is mounted in the center of the mounting surface of a flat mounting board. Each light source 10A is mounted on the base 2 as described above. Each guide portion is a translucent portion. Each guide portion faces the corresponding light source 10A on the base 2 and has an entrance surface onto which light emitted from the light source 10A enters. Each guide portion has an output surface through which light that has entered from the input surface is output to the outside of the guide portion. The output surface of each guide portion is exposed through a corresponding hole in the lower cover 51.

The display unit 10 is an operating light that notifies the outside of the operating state of the sensor 1. During normal times (when monitoring a fire), the lighting circuit of the circuit module turns off the light source 10A under the control of the control unit 9. When it is determined that a fire has occurred, the lighting circuit of the circuit module starts blinking or lighting the light source 10A under the control of the control unit 9. In FIG. 7, illustration of a lighting circuit between the control section 9 and the display section 10 is omitted.

(2.6) Control Unit The control unit 9 can be realized, for example, by a computer system including one or more processors (microprocessors) and one or more memories. That is, one or more processors function as the control unit 9 by executing one or more programs (applications) stored in one or more memories. Although the program is pre-recorded in the memory of the control unit 9 here, it may also be provided via a telecommunications line such as the Internet or by being recorded on a non-temporary recording medium such as a memory card.

The control unit 9 is configured to control the communication unit 11 and circuit modules (such as a lighting circuit and a power supply circuit).

Further, the control unit 9 is configured to receive detection signals from the heat detection unit 3 and the smoke detection chamber 4 and determine whether or not a fire has occurred. Specifically, the control unit 9 individually monitors the detection signals from the six heat detection elements 30 of the heat detection unit 3, and determines whether the signal level (corresponding to the resistance value) included in the detection signal exceeds the threshold value. (or below) If even one heat detection element 30 is found, it is determined that a fire has occurred. The control unit 9 also monitors the detection signal from the smoke detection chamber 4, and if the signal level included in the detection signal (corresponding to the amount of light received by the light receiving element 402 or the smoke density) exceeds a threshold, a fire is detected. It is determined that this has occurred.

When the control unit 9 determines that a fire has occurred based on heat detection or smoke detection, the control unit 9 transmits a signal notifying the occurrence of a fire to the receiver of the automatic fire alarm system, the fire alarm, etc. via the communication unit 11. do. The communication unit 11 is a communication interface for communicating with a receiver, a fire alarm, etc., for example by wire. The communication section 11 is communicably connected to a receiver, a fire alarm, etc. via a connection piece of the mounting section, a connector section of the mounting base, and a signal line wired on the back side of the ceiling. Further, when the control unit 9 determines that a fire has occurred, it outputs a control signal for blinking or lighting the light source 10A of the display unit 10 (operating light) to the lighting circuit of the circuit module.

(2.7) Channel-forming member The channel-forming member 7 in this embodiment is made of synthetic resin, for example, flame-retardant ABS resin. The flow path forming member 7 has a flat, generally cylindrical outer shell with an open upper surface. Specifically, the flow path forming member 7 has a base portion 70, a branch portion 71, and a blocking portion 72, as shown in FIGS. 3 and 4.

The base 70 has a disk shape. The base 70 has a pair of insertion holes 74 passing through the base 70 in its thickness direction. As described above, the pair of engagement pieces 42 of the smoke detection chamber 4 can be inserted through the pair of insertion holes 74, respectively.

The blocking portion 72 is a cylindrical portion that is continuously formed so as to protrude upward from the outer peripheral edge of the base portion 70 . In a state where the smoke detection chamber 4 is attached to the base 2 with the flow path forming member 7 sandwiched between the base 2 and the base 2, the smoke detection chamber 4 is located in a recess 75 ( (see Figure 3). With the smoke detection chamber 4 accommodated in the recess 75, the peripheral wall 41 of the smoke detection chamber 4 is generally covered by the blocking portion 72 with a predetermined gap X1 (see FIGS. 1 and 6) from the blocking portion 72. be exposed.

The branch portion 71 is a substantially annular portion that is continuously formed from the upper edge of the blocking portion 72 . Specifically, the branching portion 71 is formed to extend outward in the radial direction of the blocking portion 72 from the upper end edge of the blocking portion 72 and further protrude downward. As a result, the upper edge of the flow path forming member 7 as a whole has a "curved shape". The branch portion 71 is formed over the entire upper edge of the blocking portion 72 in the circumferential direction. With the smoke detection chamber 4 housed within the recess 75, the branch portion 71 is arranged around the smoke detection chamber 4.

The branching part 71 of this embodiment divides the space SP1 around the smoke detection chamber 4 into two in a separation direction A1 including a vertical direction A2 component, and divides the gas flow path 6 into an upper flow path 61 and a lower flow path 62. Branch into two parts. The branch portion 71 is configured to cause the smoke that has passed through the upper channel 61 to flow into the smoke detection chamber 4 from the inlet 40 . Here, the space SP1 is roughly divided into two in the vertical direction by the branching part 71. That is, the separation direction A1 generally coincides with the vertical direction A2. However, the separation direction A1 may be a direction intersecting the vertical direction A2 as long as it includes the vertical direction A2 component.

Specifically, the space SP1 is surrounded by the upper cover 52, the base 2, and the smoke detection chamber 4. The upper flow path 61 is a flow path surrounded by the upper cover 52 and the branch portion 71, and is a crank-shaped flow path in the cross-sectional view of FIG. In other words, the upper cover 52 forms a part of the upper channel 61. Therefore, compared to the case where the member forming the upper channel 61 is provided separately from the upper cover 52, the number of parts can be reduced. Further, it becomes easier to reduce the size of the sensor 1 (particularly, reduce its height).

Further, the lower flow path 62 is a straight flow path that is located below the upper flow path 61 and runs along the first surface 21 (upper surface) of the base 2 . In FIG. 1, the upper flow path 61 and the lower flow path 62 are schematically shown with arrows to make it easier to understand the direction in which the gas flows. Further, in FIG. 1, the upper flow passage 61 and the lower flow passage 62 are indicated by arrows only on the left side of the smoke detection chamber 4, but the upper flow passage 61 and the lower flow passage 62 are arranged in the circumferential direction of the smoke detection chamber 4. It is formed over almost the entire circumference at A3.

Here, the mass of the steam particles is greater than the mass of the smoke particles. By providing the branch portion 71, smoke particles, which tend to rise more easily than steam particles, tend to pass through the upper flow path 61 more dominantly than the lower flow path 62 after entering through the opening 510. Become. Therefore, the smoke particles easily overcome the branching part 71 and flow into the smoke detection chamber 4 from the inlet 40 on the back side of the blocking part 72. On the other hand, steam particles having a larger mass than smoke particles enter through the opening 510 and then pass through the lower flow path 62 more easily than the upper flow path 61. In other words, there is a high possibility that only smoke will flow into the smoke detection chamber 4 from the inlet 40 due to the branch portion 71 . As a result, the sensor 1 has the advantage of being able to reduce the possibility of false detections such as erroneously determining steam as fire smoke.

In particular, in the case of the sensor 1, since the space SP1 around the smoke detection chamber 4 is divided into two, there is a possibility that false detections may occur even though the external size of the sensor 1, which is relatively thin (low height), is maintained. can be reduced.

Further, as shown in FIG. 1, the blocking section 72 is disposed between the lower flow path 62 and the smoke detection chamber 4, and prevents steam passing through the lower flow path 62 from entering the smoke detection chamber 4. configured to block inflow. Therefore, the steam that is dominantly easier to pass through the lower flow path 62 than the upper flow path 61 due to the provision of the branch portion 71 has a higher possibility of colliding with the blocking portion 72. As a result, it becomes difficult for steam to flow into the smoke detection chamber 4, and the occurrence of false detection can be further suppressed. In particular, since the upper edge of the flow path forming member 7 has a "curved shape" as described above, the steam rises due to the reaction when it collides with the blocking part 72, climbs over the blocking part 72, and reaches the blocking part 72. It is possible to suppress the possibility that the water will reach the inlet 40 on the back side.

Further, as described above, the base 2 of this embodiment has the (six) protruding edges 25 that protrude from the cylindrical portion 511. Therefore, when steam entering from the opening 510 passes through the flow path 6A schematically indicated by the arrow in FIG. can be suppressed. In short, the protruding edge 25 can block the rise of steam.

Further, the protruding edge portion 25 protrudes so as to ensure a longer flow path length of the lower flow path 62. The longer the flow path length of the lower flow path 62 is, the easier it is to maintain straight movement due to the inertia of the steam particles, which are larger than the mass of the smoke particles. Therefore, by providing the protruding edge 25 on the base 2, it is possible to ensure a longer flow path length of the lower flow path 62, further reducing the proportion of steam rising midway and heading toward the upper flow path 61. be able to.

In this way, the rising steam is blocked by the protruding edge 25 and the straightness of the steam is maintained, so that the possibility that the steam passes through the upper flow path 61 can be reduced.

In addition, in this embodiment, the outer peripheral part 23 (here, the protruding edge part 25 and the tongue part 26) of the base 2 is arranged so that it does not protrude from the opening part 510 into the external space SP2 when the lower cover 51 is viewed from the front. It is composed of Therefore, it is possible to reduce the possibility that the outer peripheral portion 23 of the base 2 will obstruct smoke from entering into the sensor 1 from the opening 510.

(2.8) Airflow Control Wall By the way, in the peripheral wall 41 of the smoke detection chamber 4 of this embodiment, there is a region where the smoke inflow port 40 is not formed and smoke is difficult to flow into the inside of the smoke detection chamber 4. do. Here, the opposing wall 405 (see FIG. 6) of the cover 4A of the smoke detection chamber 4 corresponds to an area into which smoke is difficult to enter. When the cover 4A is assembled to the body 4B, the opposing wall 405 faces the outer surface of the holding block 404 (see FIG. 6) that holds the optical element 401 of the body 4B. In short, in the sensor 1 of this embodiment, the holding block 404 that holds the optical element 401 is arranged near the outer circumference of the body 4B, so the structure makes it difficult to arrange the inlet 40 on the outer surface side of the holding block 404. It becomes.

Below, in the peripheral wall 41 of the smoke detection chamber 4, the area where the inlet 40 is formed may be referred to as a first area 411, and the area where the inlet 40 is not formed may be referred to as a second area 412. (See Figure 5). That is, the peripheral wall 41 includes a first region 411 and a second region 412. The opposing wall 405 corresponds to the second region 412.

As described above, the smoke detection chamber 4 of this embodiment includes two (a pair) of airflow control walls 8 (see FIGS. 5 and 6). Each airflow control wall 8 is a substantially rectangular plate-shaped portion, and extends slightly beyond the outer edge of the protruding edge portion 25 of the base 2 from the peripheral wall 41 of the smoke detection chamber 4 when viewed along the vertical direction. It extends to the position of Further, each airflow control wall 8 is arranged so that its thickness direction is parallel to the tangential direction of the substantially circular base 2. 5 and 6, only two airflow control walls 8 of the upper cover 52 are shown in cross section.

As shown in FIG. 1, each airflow control wall 8 includes an L-shaped first portion 81 and a rectangular second portion 82 when viewed along its thickness direction. The first portion 81 is arranged to match the upper surface and outer circumferential surface of the branch portion 71 of the flow path forming member 7 . The second portion 82 is arranged such that the inner corner of its upper end substantially coincides with the outer corner of the lower end of the L-shaped first portion 81 . The lower end of the second portion 82 contacts the first surface 21 of the base 2 (mainly the upper surface of the protruding edge 25).

Each airflow control wall 8 also has a groove 80 at a position corresponding to the lower flow path 62. The groove portion 80 is provided to release steam that may predominantly pass through the lower flow path 62. The groove portion 80 is constituted by a lower end portion of a first portion 81, a second portion 82, and an inner side portion. With the airflow control wall 8 in contact with the base 2 and the flow path forming member 7, the groove portion 80 has a first portion 81, a second portion 82, This is a substantially rectangular opening surrounded by the base 2 and the flow path forming member 7.

As shown in FIGS. 5 and 6, the two airflow control walls 8 of this embodiment are arranged in the circumferential direction A3 of the peripheral wall 41 so that the second region 412 is sandwiched between them. As shown in FIG. 5, this corresponds to the range of the second region 412 (opposing wall 405) in the circumferential direction A3, centered on the center point P1 of the smoke detection chamber 4 when viewed from above. The first angle θ1 is approximately 40 degrees. Further, the second angle θ2 corresponding to the range between the two airflow control walls 8 in the circumferential direction A3 centered on the center point P1 is about 120 degrees. That is, the second angle θ2 is, for example, about three times the first angle θ1. In other words, the two airflow control walls 8 are each arranged at a certain angle (approximately 40 degrees here) from the second region 412 in the circumferential direction A3. Note that the numerical values regarding these angles are just examples and are not particularly limited.

Each airflow control wall 8 arranged around the smoke detection chamber 4 in this manner controls the airflow so as to reduce variations in smoke inflow into the smoke detection chamber 4 in the circumferential direction A3. Specifically, even if smoke that has entered from the external space SP2 toward the second region 412 collides with the second region 412 and is repelled along the circumferential direction A3, it is prevented from colliding with each airflow control wall 8. The air can be guided to the inlet 40 near the airflow control wall 8 (see airflow B1 indicated by the arrow in FIG. 5).

In particular, the first portion 81 of the airflow control wall 8 is provided at a position corresponding to the upper flow path 61. Therefore, as explained in the section "(2.7) Flow path forming member", the branch portion 71 allows the smoke to predominantly pass through the upper flow path 61, but the smoke passes through the upper flow path 61 along the circumferential direction A3. The smoke flowing and escaping can be efficiently collided with the first portion 81 and guided to the inlet 40.

By providing the airflow control wall 8 in this way, smoke can enter the sensor 1 from any direction within the 360 degrees surrounding the sensor 1 through the opening 510 (see FIG. 5). ), the difference in the amount that finally flows into the smoke detection chamber 4 can be small. As a result, the sensor 1 has the advantage of being able to improve the flow of smoke into the smoke detection chamber 4. Furthermore, since the airflow control wall 8 is formed as a part of the upper cover 52, the airflow control wall 8 can be stably positioned with respect to the second region 412 when the sensor 1 is assembled.

The number of airflow control walls 8 is not particularly limited, and may be one. However, as in this embodiment, the two airflow control walls 8 are arranged with the second region 412 in between in the circumferential direction A3, so that both of the smoke collided in the second region 412 and separated to the left and right are It can be efficiently guided to the inflow port 40. Therefore, the possibility that it becomes difficult for smoke to flow into the inside of the smoke detection chamber 4 can be further reduced.

As explained in the section "(2.7) Flow path forming member", the branch portion 71 of the flow path forming member 7 causes the steam to predominantly pass through the lower flow path 62, but the air flow There is a possibility that the liquid collides with the control wall 8, climbs over the branch part 71, and passes through the upper flow path 61. However, in this embodiment, as described above, the groove portion 80 is provided at a position corresponding to the lower flow path 62. Therefore, the steam flowing in the lower flow path 62 along the circumferential direction A3 easily passes through the groove portion 80 of the airflow control wall 8. As a result, the possibility that the steam collides with the airflow control wall 8, climbs over the branch portion 71, and passes through the upper channel 61 can be reduced.

By the way, the branch portion 71 of this embodiment is not formed all around the smoke detection chamber 4, but has a notch 73 (see FIGS. 3 to 6). The cutout 73 is provided at a position facing the second region 412. Here, the notch 73 is formed to extend not only to the branch portion 71 but also to the blocking portion 72. That is, both the branching part 71 and the blocking part 72 are partially missing in the circumferential direction A3 due to the notch 73, and have a substantially C-shape when viewed along the up-down direction. The width dimension of the notch 73 in the circumferential direction A3 is approximately equal to that of the second region 412. That is, when the notch 73 is viewed from the front, substantially the entire second region 412 is exposed.

By providing the cutout 73 in this way, smoke that has entered the sensor 1 toward the second region 412 can pass between the peripheral wall 41 of the smoke detection chamber 4 and the blocking portion 72 through the cutout 73. The airflow easily enters the gap X1 between the two (see the airflow B2 indicated by the arrow in FIG. 5). Therefore, the possibility that smoke becomes difficult to flow into the smoke detection chamber 4 can be further reduced.

In particular, the flow path forming member 7 prevents steam from entering the smoke detection chamber 4, but since the second region 412 exists, there is no need for the branch section 71 and the blocking section 72 in that part. , steam heading toward the second region 412 is likely to be blocked by the second region 412. Conversely, if in addition to the presence of the second region 412, the branch portion 71 and the blocking portion 72 are present in that portion, the inflow of smoke will be synergistically obstructed. From these viewpoints, the provision of the cutout 73 improves smoke inflow.

(2.9) Installation orientation By the way, it will be explained that the flow path forming member 7 of the sensor 1 is provided with a notch 73 at a position facing the second region 412 in consideration of smoke inflow. did. Here, for example, when the sensor 1 is installed in an environment where steam easily enters the smoke detection chamber 4 (for example, a changing room near a bathroom), the sensor 1 may be installed with the notch 73 side facing the bathroom side. If installed on the construction surface 100, there is a high possibility that steam will be allowed to flow in.

Therefore, the sensor 1 further includes a mark M1 that indicates the installation direction in the circumferential direction A4 of the sensor 1 when the sensor 1 is installed on the construction surface 100 (see FIGS. 2 to 6). The mark M1 is provided, for example, on the cylindrical body 51A of the lower cover 51. The mark M1 is a linear mark along the vertical direction, but the shape of the mark is not particularly limited. In this embodiment, as an example, a mark M1 is provided at a position corresponding to the notch 73 in the circumferential direction A4 of the sensor 1. In other words, the mark M1 is arranged so that a virtual line segment connecting the mark M1 and the center point P1 of the smoke detection chamber 4 when viewed from above passes through the notch 73. In other words, it can be said that the mark M1 indicates the direction related to the notch 73.

The mark M1 may be printed directly on the lower cover 51, or a printed sticker may be attached to the lower cover 51. Alternatively, the mark M1 may be a recess or a projection formed on the surface of the lower cover 51.

The installer who installs the sensor 1 can easily prevent the notch 73 from facing toward the bathroom by installing the sensor 1 on the construction surface 100 with the mark M1 facing away from the bathroom. It can be avoided. Therefore, the sensor 1 can be installed so that the specific area (the area where the notch 73 is present) in the circumferential direction A4 of the sensor 1 does not face a specific place (bathroom).

The mark M1 may be provided at a position corresponding to an area where the notch 73 does not exist. In this case as well, it can be said that the mark M1 indicates the direction related to the notch 73. The builder can easily prevent the cutout 73 from facing toward the bathroom by installing the sensor 1 on the construction surface 100 with the mark M1 facing toward the bathroom. Therefore, the sensor 1 can be installed such that the specific area (the area where the cutout 73 does not exist) in the circumferential direction A4 of the sensor 1 faces a specific place (bathroom).

(3) Modifications The above embodiment is just one of various embodiments of the present disclosure. The embodiments described above can be modified in various ways depending on the design, etc., as long as the objective of the present disclosure can be achieved.

Modifications of the above embodiment will be listed below. The modified examples described below can be applied in combination as appropriate. Below, the above embodiment may be referred to as a "basic example".

In the basic example, the sensor 1 includes a flow path forming member 7. However, the flow path forming member 7 is not an essential component for the sensor 1 of the present disclosure, and may be omitted as appropriate. Even if the flow path forming member 7 is omitted, the smoke inflow into the smoke detection chamber 4 can be improved.

In the basic example, the flow path forming member 7 of the sensor 1 has a notch 73. However, the cutout 73 is not an essential component for the sensor 1 in the present disclosure. For example, FIG. 8 shows a sensor 1B of a first modification. The sensor 1B includes an airflow control wall 8 and a base 2 having a protruding edge 25, similar to the sensor 1 of the basic example. However, the branch portion 71A of the sensor 1B is different from the sensor 1 of the basic example in that it is formed over the entire circumference of the smoke detection chamber 4. Also in this sensor 1B, it is possible to improve the smoke inflow into the smoke detection chamber 4. Furthermore, the possibility of false detection occurring can be reduced. Further, in the sensor 1B, steam is difficult to flow into the smoke detection chamber 4 no matter which direction of 360 degrees it enters into the sensor 1.

In the basic example, the notch 73 is formed across both the branch part 71 and the blocking part 72. However, the cutout 73 may be formed only in the branch portion 71. In other words, the cutout 73 may be formed only at a position corresponding to the upper channel 61.

In the basic example, the branch portion 71 of the flow path forming member 7 of the sensor 1 has a cross-sectional shape bent at a right angle in an L-shape (see FIG. 1). However, the shape of the branch portion 71 is not particularly limited. For example, FIG. 9 shows a cross-sectional view of a main part of a sensor 1C according to a second modification. The flow path forming member 7 of the sensor 1C is different from the sensor 1 of the basic example in that it has a branch portion 71B having an inclined surface 76. The inclined surface 76 is inclined in a direction closer to the base 2 as it is further away from the upper end of the blocking portion 72 outward. Therefore, smoke particles can more easily overcome the branch part 71B through the inclined surface 76 than in the sensor 1 of the basic example, and can more easily flow into the smoke detection chamber 4 from the inlet 40 on the back side of the blocking part 72.

In the basic example, the base 2 of the sensor 1 has a protruding edge 25 . However, the protruding edge 25 is not an essential component for the sensor 1 in the present disclosure. As shown in FIG. 10, the sensor 1 may include a base 2A that does not have any protruding edge 25 and only has a main body 20 and six tongues 26. In FIG. 10, for ease of comparison, the protruding edge 25 that the base 2 of the sensor 1 of the basic example had is illustrated with a chain double-dashed line. In FIG. 10, illustration of the heat detection element 30 is omitted.

In the basic example, the number of airflow control walls 8 is two, but is not particularly limited, and may be one, or three or more.

In the basic example, the airflow control wall 8 is arranged with reference to the second region 412, which is the opposing wall 405 facing the outer surface of the holding block 404 that holds the optical element 401. However, if the airflow control wall 8 controls the airflow so as to reduce the variation in smoke inflow into the smoke detection chamber 4 in the circumferential direction A3 of the smoke detection chamber 4, the airflow control wall 8 may be arranged with the second region 412 as a reference. It doesn't have to be done.

In the basic example, the airflow control wall 8 is formed as part of the upper cover 52 . However, at least a portion of the airflow control wall 8 may be separate from the upper cover 52. For example, the first portion 81 of the airflow control wall 8 may be formed integrally with the flow path forming member 7. Further, for example, the second portion 82 of the airflow control wall 8 may be fixed to the base 2 with an adhesive or the like.

In the basic example, it is assumed that the second region 412 is the opposing wall 405 that faces the outer surface of the holding block 404 that holds the optical element 401. However, the second region 412 may be an opposing wall of the cover 4A that faces the outer surface of the holding block 406 (see FIG. 6) that holds the light receiving element 402.

In the basic example, the smoke detection chamber 4 is mounted on the first surface 21 (upper surface) of the base 2. However, the smoke detection chamber 4 may be mounted on the second surface 22 (lower surface) of the base 2.

In the basic example, the base 2 on which the smoke detection chamber 4 is mounted is a circuit board on which the control section 9 and the like are also mounted. However, the base 2 may be provided separately from the circuit board on which the control section 9 and the like are mounted. However, the basic example can reduce the number of parts.

In the basic example, the mark M1 indicates the orientation related to the notch 73. However, the mark M1 is not limited to the direction related to the notch 73, as long as it indicates the direction related to the specific area in the circumferential direction A4 of the sensor 1.

The mark M1 may be realized by light emitted from a light source such as an LED. In this case, the display unit 10, which is an operating light, may also serve as the mark M1.

(4) Summary As explained above, the sensor (1, 1B, 1C) according to the first aspect includes a smoke detection chamber (4) and at least one airflow control wall (8). The smoke detection chamber (4) has an inlet (40) through which smoke flows. An airflow control wall (8) is arranged around the smoke detection chamber (4). The airflow control wall (8) controls the airflow so as to reduce variations in smoke inflow into the smoke detection chamber (4) in the circumferential direction (A3) of the smoke detection chamber (4). According to the first aspect, it is possible to improve the smoke inflow into the smoke detection chamber (4).

Regarding the sensor (1, 1B, 1C) according to the second aspect, in the first aspect, the peripheral wall (41) of the smoke detection chamber (4) has a first area ( 411) and a second region (412) in which no inlet (40) is formed. The at least one airflow control wall (8) includes two airflow control walls (8). The two airflow control walls (8) are arranged in the circumferential direction (A3) of the peripheral wall (41) so that they sandwich the second region (412) between them. According to the second aspect, the possibility that smoke entering the sensor (1, 1B, 1C) toward the second region (412) becomes difficult to flow into the smoke detection chamber (4) is reduced. Can be reduced.

The sensor (1, 1B, 1C) according to the third aspect further includes a branch part (71, 71A, 71B) in the first or second aspect. The branch portions (71, 71A, 71B) are arranged around the smoke detection chamber (4), and are arranged to move the space (SP1) around the smoke detection chamber (4) in a separation direction (including a vertical direction (A2) component). A1), and the gas flow path (6) is branched into two, an upper flow path (61) and a lower flow path (62). The branch part (71, 71A, 71B) directs the smoke that has passed through the upper channel (61) of the upper channel (61) and the lower channel (62) from the inlet (40) to the smoke detection chamber ( 4). According to the third aspect, it is possible to improve the inflow of smoke into the smoke detection chamber (4) and reduce the possibility of false detection caused by steam.

In the third aspect, the sensor (1, 1B, 1C) according to the fourth aspect is arranged between the lower flow path (62) and the smoke detection chamber (4), and is arranged between the lower flow path (62) and the smoke detection chamber (4). The smoke detection chamber (4) further includes a blocking part (72) that blocks steam passing through the smoke detection chamber (4) from flowing into the smoke detection chamber (4). According to the fourth aspect, it becomes more difficult for steam to flow into the smoke detection chamber (4), and the occurrence of false detection can be further suppressed.

Regarding the sensor (1, 1B, 1C) according to the fifth aspect, in the fourth aspect, the airflow control wall (8) has a groove (80) at a position corresponding to the lower flow path (62). According to the fifth aspect, it is possible to reduce the possibility that steam collides with the airflow control wall (8), climbs over the branch portion (71, 71A, 71B), and passes through the upper channel (61).

Regarding the sensor (1, 1B, 1C) according to the sixth aspect, in any one of the third to fifth aspects, the branch part (71, 71A, 71B) is connected to the entire smoke detection chamber (4). It is formed around the circumference. According to the sixth aspect, no matter which direction steam enters the sensor (1, 1B, 1C) in 360 degrees, it becomes difficult to flow into the smoke detection chamber (4), thereby preventing the occurrence of false detection. It can be further suppressed.

In the sensor (1, 1B, 1C) according to the seventh aspect, in any one of the third to sixth aspects, the peripheral wall (41) of the smoke detection chamber (4) has an inlet (40). It includes a first region (411) in which an inlet (40) is formed and a second region (412) in which an inlet (40) is not formed. The branch portion (71, 71A, 71B) has a notch (73) at a position facing the second region (412). According to the seventh aspect, the possibility that smoke entering the sensor (1, 1B, 1C) toward the second region (412) becomes difficult to flow into the smoke detection chamber (4) is reduced. It can be further reduced.

The sensor (1, 1B, 1C) according to the eighth aspect is a sensor (1, 1B, 1C) according to any one of the first to seventh aspects, when the sensor (1, 1B, 1C) is installed on the construction surface (100). Further, a mark (M1) is provided to indicate the installation direction of the sensor (1, 1B, 1C) in the circumferential direction (A4). According to the eighth aspect, the sensor ( 1, 1B, 1C) can be installed.

The sensor (1, 1B, 1C) according to the ninth aspect is provided with an upper cover (52) arranged to cover the smoke detection chamber (4) from above in any one of the first to eighth aspects. ). According to the ninth aspect, it is possible to improve the inflow of smoke into the smoke detection chamber located under the upper cover (52).

Regarding the sensor (1, 1B, 1C) according to the tenth aspect, in the ninth aspect, the airflow control wall (8) is formed as part of the upper cover (52). According to the tenth aspect, the airflow control wall (8) can be stably positioned.

The configurations according to the second to tenth aspects are not essential to the sensor (1, 1B, 1C) and can be omitted as appropriate.

1, 1B, 1C Detector 4 Smoke detection chamber 40 Inlet 41 Peripheral wall 411 First region 412 Second region 52 Upper cover 6 Channel 61 Upper channel 62 Lower channel 71, 71A, 71B Branch section 72 Blocking section 73 Notch 8 Airflow control wall 80 Groove 100 Construction surface A1 Separation direction A2 Vertical direction A3, A4 Circumferential direction M1 Mark SP1 Surrounding space

Claims (4)

cover and
a smoke detection chamber housed in the cover and having an inlet through which smoke flows;
at least one airflow control wall disposed around the smoke detection chamber in a manner extending from the smoke detection chamber side toward the peripheral wall side of the cover;
Equipped with
sensor. Further comprising a branching part arranged around the smoke detection chamber to branch a gas flow path in a space around the smoke detection chamber.
The sensor according to claim 1. Furthermore, it is equipped with multiple heat detection elements,
The plurality of heat detection elements are arranged around the smoke detection chamber such that the airflow control wall is located between two adjacent heat detection elements in the plurality of heat detection elements in the circumferential direction of the smoke detection chamber. placed in
The sensor according to claim 1 or 2. A fire alarm system comprising the sensor according to any one of claims 1 to 3 and a receiver communicating with the sensor.

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