JP7736659B2 - heat detector - Google Patents

Description

The present invention relates to a heat detector that can be attached to a ceiling surface, etc.

A heat detector, one example of a fire detector, detects heat, smoke, etc. and sends a fire signal to a fire receiver. The fire receiver then issues a fire alarm upon receiving the fire signal. Many cultural properties are made from materials such as wood, which are vulnerable to fire, so fire prevention measures are important. However, installing fire detectors on cultural properties is not recommended as it significantly affects the aesthetic appearance of the property.

For cultural properties, differential distributed heat detectors, such as those described in Patent Document 1, can be used. A differential distributed heat detector runs a thin copper air pipe through the fire detection area, detecting the air expansion inside the air pipe due to the sudden temperature rise caused by a fire, thereby detecting a fire. While differential distributed heat detectors are less aesthetically disturbing than regular fire detectors, the copper pipe is widely exposed in the fire detection area, which still affects the aesthetics. Furthermore, differential distributed heat detectors cannot be automatically tested. Furthermore, the heat detection type is only differential, and it cannot be changed to a constant temperature type by changing the software. Furthermore, special construction is required to run the copper pipe, which is costly.

Furthermore, fire detectors used in locations where flammable gases are likely to be generated must have an explosion-proof structure, as described in Patent Document 2. Explosion-proof fire detectors have a special structure that prevents flammable gases from entering the circuit board area, which increases their cost. Furthermore, fire detectors used in high-temperature areas must use circuit boards that do not deteriorate even at high temperatures, which also increases their cost.

JP 2011-145107 A Japanese Patent Application Laid-Open No. 2022-40664

The objective of the present invention is to provide a heat detector that does not impair the aesthetic appearance of the installation area and is not costly even when used in explosion-proof or high-temperature areas.

In one embodiment of the present invention, a heat detector comprises a sensor unit equipped with a thermistor, a detection unit, and monitoring wiring connecting the sensor unit and the detection unit. The detection unit is characterized by having a resistance detection unit to which the monitoring wiring is connected, a fire detection unit that detects a fire based on a resistance value signal obtained by the resistance detection unit, and a transmission unit that transmits the detection result of the fire detection unit.

This invention makes it possible to obtain a heat detector that can be used in explosion-proof and high-temperature areas at low cost without compromising the aesthetics of the installation location.

FIG. 2 is a diagram showing a heat detector installed in a cultural property building in Example 1. FIG. 2 is a block diagram of a detection unit according to the first embodiment. FIG. 4 is a cross-sectional view of a sensor unit installed on a ceiling board in the first embodiment. 10 is a cross-sectional view of a sensor unit installed on a ceiling panel via a mounting base in Modification 1. FIG. 10 is a cross-sectional view of a sensor unit installed above a ceiling panel in Modification 2. FIG. Cross-sectional view of a sensor unit installed in the main building in variant example 3. FIG. 10 is a diagram showing a heat detector installed in a factory having an explosion-proof area in Example 2. FIG. 13 is a diagram showing a detection unit having a display unit in Modification 4.

Figure 1 shows a heat detector 1 installed in cultural property building C. Heat detector 1 is configured with a heat-sensing sensor unit 11 and a detection unit 12 connected by monitoring wiring 13. Detection unit 12 is also connected to fire receiver 2 via wiring 3. Heat detector 1 detects a fire using detection unit 12 based on the heat detected by sensor unit 11, and reports the fire to fire receiver 2 via wiring 3.

As shown in Figure 1, the heat detector 1 has one or more sensor units 11, which are installed on the ceiling board Cc in the public area P of the cultural property building C. It is preferable to distribute the sensor units 11 in installation locations according to the area in which they can detect heat. Furthermore, the detection unit 12 is installed in the backyard B. The monitoring wiring 13 connecting the sensor units 11 and 12 runs above the ceiling board Cc. In the public area P, the protective tube 112 of the sensor unit 11, which is part of the sensor unit 11, is visible, but the monitoring wiring 13 and detection unit 12 are not visible from the public area P.

The sensor unit 11 does not have a circuit board. On the other hand, the detection unit 12 has a circuit board. Figure 2 shows a block diagram of the detection unit 12. In the detection unit 12, the resistance detection unit 121, fire detection unit 122, and transmission unit 123 are formed by circuits on the circuit board. The circuit on the circuit board in Example 1 includes a CPU and memory. The resistance detection unit 121 is connected to the monitoring wiring 13 and is connected to the fire detection unit 122 inside the detection unit 12. The fire detection unit 122 is also connected to the transmission unit 123 inside the detection unit 12. The transmission unit 123 is connected to wiring 3.

The detection unit 12, which includes a circuit board that forms the resistance detection unit 121, the fire detection unit 122 that detects a fire based on the resistance value obtained by the resistance detection unit 121, and the transmission unit 123 that transmits the detection results of the fire detection unit 122, is installed in the backyard B. As a result, the detection unit 12 is not exposed in the public area P, and the sensor unit 11 installed in the public area P can be made small and inconspicuous in appearance.

The sensor unit 11 of Example 1 is attached to the ceiling panel Cc as shown in Figure 3. In the sensor unit 11, the thermistor 111 is housed in a protective tube 112. The thermistor 111 is connected to the monitoring wiring 13 inside a base 113 provided at the base end of the protective tube 112. In Figure 3, the monitoring wiring 13 is shown as a single line, but it is actually composed of two conductors: a voltage supply line and an earth line. In addition, two mounting springs 114 extend from the base 113 in the opposite direction to the protective tube 112.

The mounting springs 114 are bent at multiple locations. Furthermore, the mounting springs 114 are attached diagonally outward from the base 113. When attaching the sensor unit 11 to the ceiling board Cc, a hole H is drilled in the ceiling board Cc. The two mounting springs 114 of the sensor unit 11 are then compressed and inserted into the hole H from the underside of the ceiling board Cc, all the way to the base 113. The mounting springs 114 expand inside the hole H and are locked at the bent portions. Only the thin protective tube 112 of the sensor unit 11 and a portion of the base 113 are exposed from the ceiling board Cc. The base 113 is not entirely exposed, and the mounting springs 114 are located on the back side of the ceiling board Cc, i.e., in a location that is not visible from the installation location, thereby minimizing the amount of heat detector 1 exposed at the installation location. Furthermore, the area of the base 113 exposed below the ceiling board Cc is small. Therefore, the sensor unit 11 does not substantially impair the aesthetic appearance of the installation location. The sensor unit 11 of Example 1 is effective when the ceiling board Cc is formed from a ceiling board with a certain thickness.

The resistance detection unit 121 of the detection unit 12 shown in FIG. 2 is connected to the monitoring wiring 13 from multiple sensor units 11. The resistance detection unit 121 applies a voltage between the voltage supply wire and the ground wire of the multiple monitoring wiring 13 corresponding to each sensor unit 11 to detect resistance values, and outputs a digital resistance value signal to the fire detection unit 122. The resistance value signal indicates the resistance value of the thermistor 111 connected to the end of the monitoring wiring 13. When a fire occurs and the temperature rises, the resistance value of the thermistor 111 decreases, reducing the resistance value between the monitoring wiring 13 and the resistance value signal output by the resistance detection unit 121, causing the fire detection unit 122 to determine a fire. When a fire is determined to be a fire, the fire detection unit 122 commands the transmission unit 123 to transmit a fire signal. The fire signal is then transmitted from the transmission unit 123 to the fire receiver 2 connected via wiring 3. The fire receiver 2 receives the fire signal from wiring 3 and issues a fire alarm. Depending on the thermistor's characteristics, the resistance may increase as the temperature rises, so either type may be used.

The fire detection unit 122 makes a determination using software stored in memory provided in the detection unit 12. The determination software may be a constant temperature type that makes a determination using a resistance value that indicates the temperature, or a differential type that makes a determination using the resistance value change rate that indicates the rate of temperature change. The temperature and temperature change rate at which a fire is determined may also be determined depending on the installation location and stored in memory provided in the detection unit 12.

The heat detector 1 of Example 1 can be automatically tested. The fire receiver 2 or detection unit 12 is equipped with an automatic testing unit (not shown) that automatically tests the sensor unit 11. The automatic testing unit determines that the heat detector 1 is abnormal if the resistance value indicated by the resistance signal input to the fire determination unit 122 is an abnormal resistance value that cannot be obtained by temperature change. If the thermistor 111 or monitoring wiring 13, etc. is disconnected, or if the monitoring wiring 13, etc. is short-circuited due to poor insulation, an extremely high or low resistance value is detected and determined to be abnormal. The sensor unit 11 that is displaying the abnormal resistance value is then identified and displayed on a display unit (not shown) provided in the detection unit 12. Furthermore, a device abnormality signal is sent to the fire receiver 2.

In Example 1, if any of the multiple sensor units 11 provided in the fire detection unit 122 obtains a high resistance value, the fire detection unit 122 causes the transmission unit 123 to transmit a fire signal. Therefore, the occurrence of a fire is notified to the fire receiver 2, but which sensor unit 11 detected the fire is not communicated to the fire receiver 2. By assigning a unique identification number to each sensor unit 11 so that they can be identified, determining which sensor unit 11 obtained a high resistance value, transmitting an identification signal for the sensor unit 11 that has determined there is a fire from the transmission unit 123, and communicating which sensor unit 11 detected the fire to the fire receiver 2, it becomes possible to identify which sensor unit 11 detected the fire from multiple sensor units 11.

<Modification 1>
Variation 1 is a variation of the sensor unit 11 in Example 1. The configuration of the detection unit 12 and the like is the same as in Example 1. In cases where the ceiling plate Cc is thin or where it is desired to hide the lower edge of the hole H provided in the ceiling plate Cc, the sensor unit 14 and mounting base 15 shown in FIG. 4 can be used instead of the sensor unit 11. The mounting base 15 includes a cylindrical portion 151 and a flange portion 152. The mounting base 15 has two mounting springs 153 on the side of the cylindrical portion 151 opposite the flange portion 152. The two mounting springs 153 are attached obliquely outward from the cylindrical portion 151.

When attaching the sensor unit 14 to the ceiling plate Cc, first tighten the two mounting springs 153 on the mounting base 15 and insert it from below into the hole H provided in the ceiling plate Cc. Then, push the mounting base 15 in until the flange portion 152 abuts the ceiling plate Cc. This causes the mounting springs 153 to expand on the upper side of the ceiling plate Cc, securing the mounting base 15 to the ceiling plate Cc. Then, insert the base 143 of the sensor unit 14 from below into the inside of the cylindrical portion 151 of the mounting base 15. The mounting base 15 and sensor unit 14 are secured together by a locking piece (not shown).

Even in variant 1, the ceiling plate Cc exposes only the thin protective tube 142 of the sensor unit 11, part of the base 113, and the flange 152 of the mounting base 15 at the installation location. Even in variant 1, the base 113 is not entirely exposed, and the mounting spring 153 is located behind the ceiling plate Cc, in a location that is not visible from the installation location, thereby minimizing the amount of heat detector 1 exposed at the installation location. Because the flange 152 of the mounting base 15 is thin, it protrudes only slightly from the ceiling plate Cc, and the area of its underside is small. Furthermore, only a small area of the base 143 of the sensor unit 14 is exposed below the ceiling plate Cc. As a result, the sensor unit 14 and mounting base 15 do not significantly detract from the aesthetics of the installation location.

<Modification 2>
Variation 2 is another variation of the sensor unit 11 in Example 1. The configuration of the detection unit 12 and other components is the same as in Example 1. If it is desired to reduce the size of the hole H in the ceiling plate Cc, the sensor unit 16 can be attached as shown in FIG. 5 . The sensor unit 16 has a protective tube 162, and the thermistor 161 and the monitoring wiring 13 are connected inside the protective tube 162. The protective tube 162 is fixed to a base 163. To install the sensor unit 16 on the ceiling plate Cc as shown in FIG. 5 , a hole H of approximately the same size and shape as the cross section of the protective tube 162 is drilled in the ceiling plate Cc. The protective tube 162 is then inserted into the hole H from above the ceiling plate Cc and attached to the ceiling plate Cc so that the bottom surface of the base 163 is in contact with the top surface of the ceiling plate Cc. The sensor unit 16 of Variation 2 can be used if it is possible to insert the sensor unit 16 into the hole H from above the ceiling plate Cc when installing the heat detector 1. In variant example 2, the entire base 113 is located behind the ceiling panel Cc, i.e., in a location that is not visible at the installation location, and only the thin protective tube 142 of the sensor unit 11 is exposed at the installation location, thereby minimizing the heat detector 1 that is visible at the installation location.

<Modification 3>
Variation 3 is another variation of the sensor unit 11 in Example 1. The configuration of the detection unit 12 and the like is the same as in Example 1. Fig. 6 shows the sensor unit 17 of Variation 3, which is attached to a location where there is no ceiling panel Cc in the cultural property building C2. Fig. 6 is a cross-sectional view of the vicinity of the roof of the cultural property building C2. The cultural property building C2 shown here does not have a ceiling panel Cc, and the roof panels R and purlins U of the roof material are exposed.

The sensor unit 17 is fixed to the side of the main building U. Figure 6 shows the sensor unit 17 screwed to the main building U. A flange portion 174 extending laterally from the base portion 173 of the sensor unit 17 is screwed to the main building U with screws 175. In Figure 6, only the flange portion 174 of the sensor unit 17 is shown in cross section, with the base portion 173 and protective tube 172 shown from the side. The thermistor 171 is not shown as it is located inside the protective tube 172.

The copper pipe of the differential distributed heat detector must be laid horizontally along the side of the main building U in order to detect heat, and must be placed in a position that is visible from the installation location. On the other hand, in variant 3 shown in Figure 6, the monitoring wiring 13 can be installed along the main building U, on top of the main building U, etc. Furthermore, the sensor unit 17 in Figure 6 is inconspicuous because only the protective tube 172 and a portion of the base 173 are exposed below the main building U, and does not detract from the aesthetic appearance of the cultural property building C2.

Figure 7 shows a heat detector 4 installed in a factory with an explosion-proof area. In Figure 7, the heat detector 4 is installed in a factory building F, which has an explosion-proof area E and a non-explosion-proof area S. The heat detector 4 is configured with a heat-detecting sensor unit 41 and a detection unit 42 connected by monitoring wiring 43. The detection unit 42 is also connected to the fire control unit 2 via wiring 3. The heat detector 4 detects a fire using the detection unit 42 based on the heat detected by the sensor unit 41, and reports the fire to the fire control unit 2 via wiring 3.

As shown in Figure 7, the sensor unit 41 of the heat detector 4 is installed on the ceiling board Ec in the explosion-proof area E of the factory building F. The detection unit 42 is installed in the non-explosion-proof area S. The monitoring wiring 43 connecting the sensor unit 41 and the detection unit 42 runs above the ceiling board Ec.

The sensor unit 41 is configured similarly to the sensor unit 11 of Example 1 and does not include a circuit board. The circuit board is provided in the detection unit 42. The detection unit 42 has a resistance detection unit (not shown) to which the monitoring wiring 43 is connected, a fire detection unit (not shown) that detects a fire based on the resistance value obtained by the resistance detection unit, and a transmission unit (not shown) that transmits the detection result of the fire detection unit. The detection unit 42 is also configured similarly to the detection unit 12 of Example 1, and detects a fire based on the resistance value generated in the thermistor (not shown) in the sensor unit 41 and transmits a fire signal to the fire receiver 2 via wiring 3.

Furthermore, a fire detector 5 is installed in the non-explosion-proof area S and is connected to the fire receiver 2 via wiring 3. The fire detector 5 has a circuit board inside. The fire receiver 2 receives fire signals from the detection unit 42 and the fire detector 5 and issues a fire alarm.

The sensor unit 41 installed in the explosion-proof area E does not have a circuit board. Therefore, the possibility of flammable gas in the explosion-proof area E igniting and causing an explosion is extremely low. Note that the sensor unit of the modified example shown in Example 1 may be used instead of the sensor unit 41.

<Modification 4>
Variation 4 is a variation of the detection unit 42. Fig. 8 shows a heat detector 6 including a detection unit 62 which is a variation of the detection unit 42 in Example 2. In the heat detector 6 of this variation, multiple sensor units 61 are connected to each other by monitoring wires 63. Four sensor units 61 provided in the explosion-proof area E are connected to one detection unit 62 by four monitoring wires 63. The detection unit 62 is installed in the non-explosion-proof area S. Wiring 3 is connected to the detection unit 62, and a fire signal is transmitted to the fire control panel 2.

The detection unit 62 is provided with multiple display units 624. These can display the area corresponding to the sensor unit 61 that detected a fire. As shown in Figure 8, the sensor units 61 are installed in four areas: Line A, Line B, Room C, and Line D. When a fire is detected, the corresponding display unit 624 lights up in red. The detection unit 62 also has an automatic test function, similar to Example 1. The display unit 624 lights up the area indicating the sensor unit 61 that detected an abnormality in yellow. The detection unit 62 of this modified example can display where the fire occurred in the explosion-proof area E and which sensor unit 61 the abnormality occurred in.

In Example 2, the heat detector 4 was installed in a factory building F with an explosion-proof area E, but the heat detector 4 may also be installed in a building with a high-temperature area. In that case, the sensor unit shown in the examples and variants is installed in the high-temperature area, and by detecting the temperature difference between normal and fire conditions and determining whether a fire has occurred, it is possible to detect a fire while preventing false fire alarms, even in high-temperature areas where high temperatures are always detected. The detection unit is installed in the normal-temperature area. Because the sensor unit does not have a circuit board, the circuit on the circuit board will not deteriorate due to the temperature in the high-temperature area.

In Examples 1 and 2, multiple sensor units are connected to one detection unit. However, a heat detector may also be formed by connecting one sensor unit to one detection unit.

In addition, the specific configuration is not limited to the embodiments, and the present invention includes design changes that do not deviate from the gist of the present invention. Furthermore, the above-mentioned examples and variations can be combined by utilizing each other's technology, as long as there are no particular contradictions or problems with their purpose, configuration, etc.

C Cultural property building, Cc Ceiling board, P Public area, B Backyard,
H hole,
C2 Cultural property building, U Main building, R Roof board,
F Factory building, E Explosion-proof area, Ec Ceiling panel, S Non-explosion-proof area,
1 heat detector,
11 Sensor part, 111 Thermistor, 112 Protective tube, 113 Base part, 114 Mounting spring
12 detection unit, 121 resistance detection unit, 122 fire determination unit, 123 transmission unit,
13 monitoring wiring,
14 Sensor part, 141 Thermistor, 142 Protective tube, 143 Base part,
15 Mounting base, 151 Cylindrical portion, 152 Flange portion, 153 Mounting spring,
16 Sensor part, 161 Thermistor, 162 Protective tube, 163 Base part,
17 Sensor part, 172 Protective tube, 173 Base part, 174 Flange part, 175 Screw,
2. Fire alarm receiver,
3 wiring,
4 Heat detector, 41 Sensor unit, 42 Detection unit, 43 Monitoring wiring,
5 Fire detector;
6 Heat detector, 61 Sensor unit, 62 Detection unit, 624 Display unit, 63 Monitoring wiring

Claims (5)

a sensor unit including a thermistor, a detection unit, and a monitoring wiring connecting the sensor unit and the detection unit;
The heat detector is characterized in that the detection unit has a resistance detection unit to which the monitoring wiring is connected, a fire judgment unit that judges a fire based on the resistance value signal obtained by the resistance detection unit, and a transmission unit that transmits the judgment result of the fire judgment unit. The sensor unit is housed in a protective tube and is exposed to the underside of the ceiling or main building.
The detection unit is provided at a position different from the sensor unit and is connected to a fire receiver.
2. The heat detector according to claim 1, wherein the sensor unit is provided in an explosion-proof area and the detection unit is provided in a non-explosion-proof area. The heat detector described in claim 2, characterized in that the detection unit identifies the sensor unit that has determined a fire. A heat detector as described in any one of claims 1 to 3, characterized in that the detection unit performs automatic testing. The heat detector described in claim 4, characterized in that multiple sensor units are connected to the detection unit, and the automatic test detects abnormal resistance values that cannot be obtained by temperature changes, thereby identifying the abnormal sensor unit.