Fire detector
The fire detector design leverages pressure differences to draw air without electrically driven intake, reducing current consumption and maintaining effective fire detection sensitivity.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- NOHMI BOSAI LTD
- Filing Date
- 2024-11-06
- Publication Date
- 2026-05-19
AI Technical Summary
Fire detectors of the suction type require constant operation of an electrically driven intake means, leading to increased current consumption.
A fire detector design that utilizes pressure differences between monitored and adjacent spaces to draw in air without an electrically driven intake means, incorporating features like inlets and outlets for airflow, airflow detection means, and automatic sensitivity adjustment based on airflow presence.
Reduces current consumption by allowing air to be drawn into the detector without operating electrically driven intake means, while maintaining effective fire detection sensitivity.
Smart Images
Figure 2026082042000001_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a fire detector.
Background Art
[0002] A fire detector is provided on the ceiling, wall, etc. of a fire protection object such as a building and is used to detect a fire occurring in the monitored space.
[0003] Typical fire detectors include a smoke detector that detects smoke to sense a fire and a heat detector that detects heat to sense a fire. In the case of a photoelectric smoke detector, it includes a light-emitting element and a light-receiving element. The light-receiving element receives light from the light-emitting element in the smoke detection section, and is configured to detect smoke and sense a fire based on the amount of received light (there are a scattering light type that detects smoke based on the amount of light scattered by smoke and a light attenuation type that detects smoke based on the amount of light attenuated by smoke). Further, a heat detector includes a heat-sensitive element and is configured to detect heat with the heat-sensitive element to sense a fire.
[0004] Among this type of fire detector (smoke detector), there is a suction type in which an intake means such as a suction fan is built into the detector body, air is sucked from the monitored space, and smoke is detected from the sucked air (for example, see Patent Document 1).
Prior Art Documents
Patent Documents
[0005]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0006] However, when the fire detector is of the suction type as described above, it is necessary to constantly operate an electrically driven intake means such as a suction fan, and accordingly, there is a problem that the current consumption of the fire detector increases.
[0007] In view of the above circumstances, this invention aims to provide a fire detector that can draw in air while suppressing current consumption. [Means for solving the problem]
[0008] This invention relates to a fire detector having a detector body that is embedded in an opening penetrating a ceiling or wall, mounted on a ceiling or wall, and equipped with means for detecting fire inside, wherein an inlet is provided on the front of the detector body to allow air to flow into the detector body from the space to be monitored on the front side of the ceiling or wall, and an outlet is provided on the back and / or side of the detector body to allow air to flow out from inside the detector body to the space behind the ceiling or wall, and air flows in from inside the detector body through the outlet due to an airflow generated based on the pressure in the space to be monitored being higher than the pressure in the space behind the ceiling or wall, and air flows out from inside the detector body through the outlet to the space behind the ceiling or wall.
[0009] In this invention, the fire detector may be a smoke detector or a heat detector. Furthermore, the pressure in the monitored space may be maintained at a positive pressure by supplying air from the outside via an air supply means. Furthermore, the fire detector may be configured to automatically adjust the fire detection sensitivity based on the determination result of whether or not airflow is generated. Furthermore, the fire detector may be configured to automatically adjust the fire detection sensitivity in conjunction with the on / off operation of the air supply means's operating switch. Furthermore, the fire detector may be equipped with a suction fan inside the detector body that draws air from the monitored space into the detector body through the inlet, and the suction fan may be configured to operate only when it is determined that no airflow is generated based on the determination result of whether or not airflow is generated.
[0010] Furthermore, in this invention, the fire detector may be provided together with an airflow generation detection means for detecting the generation of airflow. The determination of whether or not airflow is generated may be performed based on the output signal from the airflow generation detection means. The airflow generation detection means may be a sensor that detects the on / off state of the operation switch of the air supply means, an anemometer provided at the passage position of the airflow of the air supply means, a thermistor provided in the detector itself, or a differential pressure gauge that measures the pressure difference between the monitored space and the space behind the ceiling or wall. Furthermore, the fire detector may be provided together with a fire alarm receiver in the object to be protected from fire. The determination of whether or not airflow is generated may be performed by the fire alarm receiver based on the output signal from the airflow generation detection means. Furthermore, the automatic adjustment of the smoke or heat detection sensitivity may be performed based on the signal of the determination result of whether or not airflow is generated transmitted from the fire alarm receiver. Furthermore, the fire detector may constitute a fire detection system that detects fire in cooperation with the airflow generation detection means.
[0011] Furthermore, in this invention, the detector body may be mounted such that its front surface is substantially flush with the surface of the ceiling or wall. Also, if the fire detector is a smoke detector, an insect screen may be provided on the front surface of the detector body to prevent insects from entering the detector body through the inlet. The insect screen may be made of a flat mesh plate and may cover the inlet while making the front surface of the detector body substantially flat. The insect screen may also adjust the amount of air entering the inlet from the space being monitored. Furthermore, an airflow adjustment plate may be provided on the front surface of the detector body to adjust the amount of air entering the inlet from the space being monitored. [Effects of the Invention]
[0012] In this invention, air can be drawn into the sensor body from the space being monitored without operating an electrically driven intake means.
[0013] Therefore, according to this invention, it is possible to provide a fire detector that can draw in air while suppressing current consumption. [Brief explanation of the drawing]
[0014] [Figure 1] This diagram shows an example of an embodiment of the fire detector of this invention (an example of application to a smoke detector), and is a schematic explanatory diagram showing a smoke detector in cross-sectional view installed in an opening that penetrates the front and back of the ceiling. Note that the circuit board and other components installed inside the detector body are not shown. [Figure 2] This is an explanatory diagram illustrating the functional configuration inside the detector body of the fire detector mentioned above, presented as a block diagram. [Figure 3] This is an explanatory diagram that schematically shows the installation status of the fire detector, along with the entire installation space, in a cross-sectional view. [Figure 4] This shows an example of a fire detector equipped with a ventilation adjustment plate. (a) is a schematic diagram showing the front side of the ventilation adjustment plate in a top view, and (b) is a schematic diagram showing the fire detector with the ventilation adjustment plate attached in a side view. [Figure 5] This diagram shows another example of an embodiment of the fire detector of this invention (an example of application to a heat detector), and is an explanatory diagram corresponding to Figure 1. As with Figure 1, the circuit board and other components installed inside the detector body are not shown. [Modes for carrying out the invention]
[0015] The embodiments of the fire detector of this invention will be described below with reference to the drawings.
[0016] Here, in the following description, terms indicating positions and directions such as "front", "front side", "back", and "back side" are used with the side facing the space to be monitored as the "front" or "front side", and the opposite side as the "back" or "back side".
[0017] [Smoke detector] First, a configuration example when this invention is applied to a smoke detector will be described as a smoke detector 1 (an example of a fire detector), with reference to FIGS. 1 to 4.
[0018] The smoke detector 1 has a case-shaped detector main body 2, and includes a smoke detection unit 3 (an example of a fire detection means) inside the detector main body 2 at 2c, and is used as a fire detector. An inlet 2aa for allowing air (air containing smoke) to flow from the outside (the indoor space R described later) into the inside 2c is provided on the front surface 2a of the detector main body 2, and an outlet 2ba for allowing air (air containing smoke) to flow from the inside 2c to the outside (the ceiling back space U described later) is provided on the back surface 2b. The smoke detection unit 3 is located between the inlet 2aa and the outlet 2ba, and is arranged such that the air (air containing smoke) flowing from the inlet 2aa to the outlet 2ba passes through the inside of the smoke detection unit 3 (see FIG. 1 above).
[0019] The smoke detector 1 is a photoelectric type, and a light emitting element 3a and a light receiving element 3b are provided in the smoke detection unit 3, and the light receiving element 3b detects smoke based on the amount of light from the light emitting element 3a that is received by the smoke in the air flowing into the smoke detection unit 3. A control unit 4 for performing various control processes is further provided inside the detector main body 2 at 2c. The smoke detection process is performed by the control unit 4 (see FIGS. 1 and 2 above).
[0020] Here, for the photoelectric type, there are a scattered light type that detects smoke based on the amount of light received by the smoke scattered by the smoke, and a light attenuation type that detects smoke based on the amount of light attenuated by the smoke. The example shown in FIG. 1 shows the case where the smoke detector 1 is a light attenuation type, but the detection method is not limited to the light attenuation type, and it can also be a scattered light type.
[0021] [Smoke suction function] The smoke detector 1 monitors, for example, the indoor space R of a fire protection target such as a building as the monitored space, and is installed on the ceiling T thereof. More specifically, the front surface 2a provided with the inlet 2aa is exposed to the indoor space R on the front side of the ceiling T (an example of the space on the front side of the ceiling or wall), within the opening K formed by penetrating the front and back of the ceiling T, and the back surface 2b provided with the outlet 2ba is embedded and installed in a state of being exposed to the ceiling cavity U on the back side of the ceiling T (an example of the space on the back side of the ceiling or wall) (see FIGS. 1 and 3 above).
[0022] And the pressure in the indoor space R is maintained higher than that in the ceiling cavity U. Therefore, due to the pressure difference between the two, an air flow A1 is generated from the indoor space R into the inlet 2aa of the sensor body 2 in the opening K, flowing into the interior 2c, passing through the smoke detection section 3, and flowing from the outlet 2ba into the ceiling cavity U (see FIGS. 1 and 3 above).
[0023] Therefore, in the smoke detector 1, even without operating the electrically driven intake means, air (air containing smoke) can be sucked from the indoor space R into the smoke detection section 3 by the air flow A1, and the current consumption can be suppressed.
[0024] <Q [Specific example of the sensor body] The sensor body 2 has a cylindrical shape as a whole. The inlet 2aa provided on the front surface 2a is provided as an opening facing the front indoor space R. The outlet 2ba provided on the back surface 2b is also provided as an opening facing the back ceiling cavity U (see FIGS. 1 and 3 above).
[0025] Regarding the outlet 2ba, it may be provided on the side surface 2d instead of or in addition to the back surface 2d.
[0026] [Insect screen] The front surface 2a of the detector body 2 is further provided with an insect screen 2ab that covers the inlet 2aa from the front and prevents insects from entering the interior 2c from the inlet 2aa. The insect screen 2ab is made of a flat mesh plate and is provided to cover the inlet 2aa while making the front surface 2a substantially flat. In other words, the front surface 2a of the detector body 2 is substantially flat by the insect screen 2ab (see Figure 1 above).
[0027] Furthermore, an insect screen 2bb is provided on the back surface 2b of the sensor body 2 to cover the outlet 2ba from behind and prevent insects from entering the interior 2c from the outlet 2ba. The insect screen 2bb, like the insect screen 2ab, is made of a flat mesh plate and is provided to cover the outlet 2ba while making the back surface 2b almost completely flat. In other words, the back surface of the sensor body 2 is also made almost completely flat by the insect screen 2bb (see Figure 1 above).
[0028] Furthermore, the insect screen 2ab on the front 2a side can be modified to adjust the amount of air flowing from the inlet 2aa into the interior 2c by changing the mesh size or other means.
[0029] [Flush installation configuration] The sensor body 2 can be installed such that its front surface 2a is substantially flush with the surface of the ceiling T (ceiling surface). This eliminates the need for any part to protrude into the indoor space R (see Figures 1 and 3 above).
[0030] Furthermore, as will be explained later, the smoke detector 1 may also be installed on the wall. In that case as well, the detector body 2 may be installed so that its front surface 2a is substantially flush with the wall surface.
[0031] [Mounting base] The sensor body 2 is mounted inside the opening K via a cylindrical mounting base 6 that is installed inside the opening K (see Figure 1).
[0032] [Positive pressure monitoring space] More specifically, within the indoor space R, air is mechanically supplied from the outside by an air supply device 20 (an example of an air supply means) and maintained at a positive pressure. That is, the air supply device 20 mechanically maintains a higher pressure than that within the ceiling space U. The air supply device 20 is installed in the indoor space R together with an exhaust device 21 that naturally discharges air from the indoor space R to the outside (see Figure 3 for details).
[0033] In other words, the indoor space R is a space that is ventilated by a Type 2 ventilation system consisting of mechanical air supply and natural exhaust, and the smoke detector 1 can be installed to monitor the indoor space R that is ventilated in such a manner.
[0034] [Sensitivity adjustment function] The smoke detector 1 has a sensitivity adjustment function that adjusts the smoke detection sensitivity in the smoke detection unit 3 (this is an example of fire detection sensitivity, and is the smoke concentration that triggers the fire detection alarm).
[0035] Here, if airflow A1 is not generated, the smoke detector 1 cannot draw air (air containing smoke) into the smoke detection section 3, resulting in a smaller amount of smoke entering the smoke detection section 3. Even when airflow A1 is not generated, smoke can be easily detected by adjusting the smoke detection sensitivity to a higher level.
[0036] [Sensitivity adjustment function based on the presence or absence of airflow generation] The smoke detector 1 has an automatic adjustment function that automatically adjusts the smoke detection sensitivity based on the determination of whether or not airflow A1 is generated. This automatic adjustment can be performed by the control unit 4.
[0037] As for the mode of automatic adjustment, when it is determined that airflow A1 is present, the detection sensitivity can be automatically adjusted to the standard smoke detection sensitivity. Conversely, when it is determined that airflow A1 is not present, the detection sensitivity can be automatically adjusted to a higher level than the standard smoke detection sensitivity.
[0038] [Collaboration with airflow generation detection means] The determination of whether or not airflow A1 is generated can be performed based on the output signal of an airflow generation detection means installed in the fire-protected building, separate from the smoke detector 1. In this case, the smoke detector 1 will constitute a fire detection system that works in cooperation with the airflow generation detection means to detect a fire.
[0039] • On / Off Sensor As a means for detecting airflow generation, for example, a sensor (not shown) that detects the on / off state of the operating switch of the air supply device 20 can be used, and the presence or absence of airflow A1 can be determined based on the output signal of such a sensor. In this case, the smoke detector 1 can automatically adjust the smoke detection sensitivity in conjunction with the on / off operation of the operating switch of the air supply device 20.
[0040] • Anemometer, differential pressure gauge Furthermore, as means for detecting airflow generation, for example, an anemometer (not shown) or thermistor (not shown) that measures the wind speed at the point where the airflow A20 supplied by the air supply device 20 passes (including the intake side position of the air supply device 20), or a differential pressure gauge (not shown) that measures the pressure difference between the indoor space R and the ceiling space U can also be used.
[0041] Furthermore, the anemometer may measure wind speed at the point where airflow A1 passes or at the point where the airflow A21 of natural exhaust from the exhaust device 21 passes. In addition, if the wind speed is measured at the point where airflow A1 passes, the anemometer may be installed on the smoke detector 1 itself.
[0042] [Sensitivity adjustment function based on airflow strength] In this case, the smoke detector 1 may also be configured to automatically adjust the smoke detection sensitivity based on the degree of airflow A1 strength measured by the anemometer.
[0043] [Addition of a fire detection function using heat] If the smoke detector 1 is to be installed within the smoke detector itself, it is preferable to use a thermistor capable of measuring temperature as the airflow generation detection means. In this way, the temperature measured by the thermistor can be used as a parameter for fire determination, and the thermistor can also be used as a fire detection means. In other words, the smoke detector 1 can be made capable of detecting fire by smoke and heat.
[0044] [Collaboration with fire alarm receivers] The smoke detector 1 is installed in the building subject to fire protection along with the fire alarm receiver 10 and is connected to the fire alarm receiver 10 by wiring. Inside the detector body 2c, there is a transmitting / receiving unit 5 that sends and receives signals to and from the fire alarm receiver 10. When smoke is detected, the smoke detector 1 transmits the detection signal (fire signal) from the transmitting / receiving unit 5 to the fire alarm receiver 10. In other words, the smoke detector 1 forms a fire detection system that works in cooperation with the fire alarm receiver 10 to detect fires.
[0045] Here, the determination of whether or not airflow A1 is generated may be performed by the smoke detector 1, but it is preferable that the fire alarm receiver 10 perform the determination (it may also be performed by a relay device installed between the two). If the fire alarm receiver 10 performs the determination, the airflow generation detection means and the fire alarm receiver 10 are connected by wiring, and the fire alarm receiver 10 performs the determination process based on the output signal from the detection means and transmits the determination result signal to the transmitting / receiving unit 5 of the smoke detector 1. The smoke detector 1 can then automatically adjust the smoke detection sensitivity based on the determination result signal. If the fire alarm receiver 10 performs the determination process in this way, the current consumption of the smoke detector 1 can be reduced, and if there are multiple smoke detectors 1, the automatic adjustment of the smoke detection sensitivity of all of them can be performed simultaneously.
[0046] In this case, the smoke detector 1 will constitute a fire detection system that works in cooperation with the fire receiver 10 and the airflow generation detection means to detect a fire.
[0047] [Suction fan] The smoke detector 1 may further include a suction fan (not shown) located between the smoke detection section 3 and the outlet 2ba inside the detector body 2, which draws air (air containing smoke) from within the indoor space R into the smoke detection section 3 via the inlet 2aa. The suction fan works in cooperation with the airflow generation detection means, etc., and is controlled to not operate when airflow A1 is present, but to operate when airflow A1 is not present, based on the determination result of whether or not airflow A1 is present.
[0048] As a result, the smoke detector 1 can draw air (air containing smoke) from within the indoor space R into the smoke detection unit 3 using the suction fan, even when no airflow A1 is generated. Furthermore, the suction fan can be configured to operate only when no airflow A1 is generated, thereby reducing current consumption even when using an electrically driven suction fan.
[0049] [Airflow adjustment means] The smoke detector 1 may further include an airflow adjustment means that adjusts the amount of air (air containing smoke) flowing into the interior 2c from the inlet 2aa by the airflow A1.
[0050] As a means for adjusting the amount of ventilation, for example, an airflow adjustment plate 7 can be used, as shown in Figures 4(a) and (b), which can adjust the opening of the inlet 2aa. The airflow adjustment plate 7 is installed on the sensor body 2 so as to cover the insect screen 2aa from the front and form the front surface 2a. It has an opening 7a located in front of the inlet 2aa and a vane 7b that rotates to adjust the opening of the opening 7a. With the airflow adjustment plate 7, the opening of the inlet 2aa can be adjusted by rotating the vane 7b to adjust the opening of the opening 7a (see Figures 4(a) and (b) above).
[0051] Furthermore, the vane 6a that adjusts the opening of the inlet 2aa may be designed to adjust the opening of the inlet 2aa by moving in a straight line.
[0052] [Heat detector] Next, an example of the configuration when this invention is applied to a heat detector will be described using heat detector 1' (an example of a fire detector) with reference to Figure 5.
[0053] The placement of heat detector 1' on the fire-protected building can be the same as that of smoke detector 1, and the explanation for the fire-protected building side is omitted by using the same reference numerals in the drawings.
[0054] The heat detector 1' has a detector body 2', and inside 2c' it is equipped with a thermistor 3' (an example of a means for detecting fire). The detector body 2' corresponds to the detector body 2 of the smoke detector 1, and has a front 2a', inlet 2aa', back 2b', outlet 2ba', and side 2d', similar to the front 2a, inlet 2aa, back 2b', outlet 2ba', and side 2d' of the detector body 2. The thermistor 3' is located between the inlet 2aa' and the outlet 2ba', and is arranged so that air (heated air) flowing from the inlet 2aa to the outlet 2ba passes through it.
[0055] Furthermore, the inside 2c' of the detector body 2' is provided with a control unit that performs various control processing and heat detection processing, similar to the smoke detector 1, as well as a transmitting and receiving unit that transmits and receives signals with the receiver 10 and the like.
[0056] The heat detector 1' is installed in the fire-protected object in the same arrangement as the smoke detector 1. That is, the detector body 2' is embedded in an opening K formed by penetrating the front and back of the ceiling T, with the front surface 2a', which has an inlet 2aa', exposed to the interior space R on the front side of the ceiling T, and the back surface 2b, which has an outlet 2ba, exposed to the ceiling space U on the back side of the ceiling T.
[0057] Furthermore, the sensor body 2' can be mounted inside the opening K via a cylindrical mounting base 6' that is installed inside the opening K, similar to the sensor body 2.
[0058] Then, due to the pressure difference between the indoor space R and the ceiling space U, airflow A1 flows into the interior 2c' of the sensor body 2' in the opening K through the inlet 2aa, passes through the thermistor 3', and flows into the ceiling space U through the outlet 2ba.
[0059] Therefore, even in the heat detector 1', the airflow A1 can draw air (heated air) from within the indoor space R into the detector body 2' without operating the electrically driven intake means, thereby reducing current consumption.
[0060] The heat detector 1', like the smoke detector 1, can have an automatic adjustment function for heat detection sensitivity (an example of fire detection sensitivity, which is the operating temperature for fire detection and alarm activation), can cooperate with means for detecting the presence or absence of airflow generation, can cooperate with a fire alarm receiver, can be equipped with a suction fan, and can be equipped with means for adjusting the amount of ventilation.
[0061] [Example of configuration changes] The embodiments of the fire detector of this invention have been described above with reference to the drawings, but this invention is not limited to the embodiments described above, and the configuration can be changed or deleted within the scope of its gist.
[0062] For example, smoke detector 1 and heat detector 1' may be installed on a wall. That is, the detector body 2 may be installed on the wall of the indoor space R in the manner described above. In this case, it is preferable that both be installed near the ceiling of the wall.
[0063] Furthermore, if the presence or absence of airflow A1 is determined by time, the airflow generation detection means can also be a timer. [Explanation of symbols]
[0064] 1: Smoke detector 2: Detector body 2a: Front 2aa: Inlet 2ab: Insect screen 2b: Back 2ba: Outlet 2bb: Insect screen 2c: Interior 2d: Side 3: Smoke detection section 3a: Light-emitting element 3b: Light-receiving element 4: Control unit 5: Transmitter / receiver unit 6: Mounting base 7: Airflow adjustment plate 7a: Opening 7b: Vanes 10: Receiver 20: Air supply device 21: Exhaust device R: Interior space T: Ceiling U: Space above ceiling K: Opening 1': Heat sensor 2': Sensor body 2a': Front 2aa': Inlet 2b': Back surface 2ba': Outlet 3': Thermistor
Claims
1. A fire detector having a detector body that is embedded in an opening penetrating a ceiling or wall, mounted on a ceiling or wall, and equipped with means for detecting fire inside, An inlet is provided on the front of the sensor body to allow air to flow into the sensor body from the space to be monitored on the front side of the ceiling or wall, and an outlet is provided on the back and / or side of the sensor body to allow air to flow out from the sensor body into the space on the back side of the ceiling or wall. A fire detector characterized in that, based on the fact that the pressure in the monitored space is higher than the pressure in the space behind the ceiling or wall, air flows from the monitored space into the detector body through the inlet, and air flows out from the detector body into the space behind the ceiling or wall through the outlet.
2. The fire detector according to claim 1, characterized in that the pressure in the space to be monitored is maintained at a positive pressure by supplying air from the outside by an air supply means.
3. The fire detector according to claim 1, characterized in that it automatically adjusts the fire detection sensitivity based on the determination result of whether or not airflow is generated.
4. The fire detector according to claim 2, characterized in that it automatically adjusts the fire detection sensitivity in conjunction with the on / off operation of the operating switch of the air supply means.
5. The sensor body is equipped with a suction fan that draws air from the space to be monitored into the sensor body through the inlet, The fire detector according to claim 1, characterized in that the suction fan operates only when it is determined that no airflow is being generated, based on the determination result of whether or not airflow is being generated.
6. The fire detector according to claim 1, characterized in that the front surface of the detector body is provided with an airflow adjustment plate for adjusting the amount of air entering the inlet from the space to be monitored.