JP7483954B2 - Heat Alarm - Google Patents

Description

The present invention relates to a heat alarm equipped with a heat detection unit.

Conventionally, a heat alarm comprises a main body provided with a substrate, and a heat detection unit that is mounted on the substrate and detects heat. The heat detection unit has a heat-sensing unit such as a thermistor at its tip. Heat from the hot air current generated by a fire is transmitted to the heat-sensing unit, and a fire is detected when the output value from the heat-sensing unit reaches or exceeds a certain value. The main body of the heat alarm is also provided with a battery and a speaker, and when a fire is detected, a sound is generated from the speaker to alert the fire. The heat detection unit is positioned so that it protrudes from the cover of the heat alarm (see, for example, Patent Document 1). In order for the heat-sensing unit to receive heat efficiently, it is necessary to provide space around it, and in the heat alarm of Patent Document 1, the heat-sensing unit is positioned on the outside of the cover.

JP 2015-141568 A

However, the thermal alarm of Patent Document 1 requires a protector to be provided on the outside of the cover to protect the heat-sensing part, which makes the thermal alarm thicker. On the other hand, if an attempt is made to make the thermal alarm thinner by placing the heat-sensing part inside the cover, the heat of the hot air flow is absorbed by the main body and the components inside the cover, etc., and the temperature of the hot air flow drops as it passes through the heat-sensing part. As a result, the heat-receiving characteristics may deteriorate compared to conventional cases in which the heat-sensing part is placed on the outside of the cover and a protector is provided.

The present invention has been made to solve the above problems, and aims to provide a thermal alarm that can obtain good heat receiving characteristics while being made thinner. Here, heat receiving characteristics refers to the difference between the actual temperature of the hot air flow and the temperature detected by the alarm, and a deterioration in heat receiving characteristics refers to an increase in the difference between the actual temperature and the detected temperature, while obtaining good heat receiving characteristics refers to being able to reduce that difference.

The thermal alarm of the present invention comprises a main body, a cover having a circulation hole and forming a circulation space between the main body and the cover, a circuit board provided on the main body so as to face the cover, two heat detection parts having a heat sensing part at their tips and adapted to detect the heat of the airflow that has flowed into the circulation space via the circulation hole and electrically connected to the board, and a middle plate provided on the main body so as to cover the board and having detection holes through which the two heat detection parts pass, the middle plate dividing the circulation space into a space in which the board is disposed and a space connected to the circulation hole, The bar has a bottom surface facing the main body portion on which the substrate is provided, and the bottom surface is provided with vertical holes which are the circulation holes and through which a vertical airflow flows, and each of the heat detection units is connected to the substrate so that the heat sensing unit is located closer to the outer periphery of the main body portion than the position where it is connected to the substrate and is located closer to the bottom surface of the cover than the substrate and the mid plate, the heat sensing units of the two heat detection units are arranged on a line passing through the center of the main body portion so as to sandwich the center of the main body portion, and the heat sensing unit of each heat detection unit is arranged outside the outer edge of the substrate.
In addition, in the thermal alarm of the present invention, the bottom surface of the cover is provided with two vertical holes facing the heat-sensing parts of each heat detection unit, and the middle plate has a middle plate side wall portion extending toward the main body portion so as to cover the outer edge of the substrate, and the middle plate side wall portion and the heat-sensing parts of each heat detection unit are arranged so that, in a vertical cross section passing through the line segment along which the heat-sensing parts of the two heat detection units are arranged, the heat-sensing parts of each heat detection unit are located closer to the outer periphery of the main body portion than the middle plate side wall portion.

The present invention provides a thermal alarm with improved detection accuracy by reducing the thickness of the thermal alarm while suppressing the temperature drop of the airflow in the circulation space before it reaches the heat-sensing unit and suppressing deterioration of the board caused by direct contact between the board and the air in the space connected to the circulation hole.

1 is a side view showing the external appearance of a thermal alarm 100 according to a first embodiment. FIG. 2 is a bottom view showing the external appearance of the thermal alarm 100. 2 is an explanatory diagram showing the internal configuration of a housing 10 of a thermal alarm 100. FIG. 4 is a cross-sectional view showing the cross section BB of FIG. 3. 4 is a cross-sectional view showing the CC cross section of FIG. 3. 3 is a cross-sectional view showing the AA section of FIG. 2. 10 is an explanatory diagram showing the internal configuration of a housing 310 of a thermal alarm 300 according to a second embodiment. FIG. 8 is a cross-sectional view showing the cross section DD of FIG. 7.

Embodiment 1.
Fig. 1 is a side view showing the external appearance of a heat alarm 100 pertaining to embodiment 1. Fig. 2 is a bottom view showing the external appearance of the heat alarm 100. The heat alarm 100 is installed in a monitored space, such as the interior of a house, and monitors the surrounding temperature. The heat alarm 100 alerts of a fire when the surrounding temperature reaches or exceeds a certain temperature.

As shown in Figures 1 and 2, the heat alarm 100 comprises a base 20 attached to the ceiling 200, a main body 40, a cover 30 with a circulation hole through which airflow flows, and a push-in member 34 provided on the cover 30. The cover 30 and the main body 40 form the housing 10 of the heat alarm 100, and the housing 10 is detachably attached to the base 20. The push-in member 34 is an inspection button that an operator presses when starting an operational test of the heat alarm 100. In the following explanation, the arrow X direction represents the width direction of the heat alarm 100, the arrow Y direction represents the depth direction, and the arrow Z direction represents the height direction.

3 is an explanatory diagram showing the configuration inside the housing 10 of the heat alarm 100. As shown in FIG. 3, the heat alarm 100 includes a speaker 70, a battery 80, and a middle plate 90 (see FIG. 4), and the speaker 70 and the middle plate 90 are installed inside the housing 10. The main body 40 includes a main body portion 41 formed in a disk shape and a board 50 on which various electronic components such as heat detection units 60a and 60b are mounted. An airflow circulation space SP is formed between the main body portion 41 and the cover 30. Hereinafter, when there is no need to particularly distinguish between the heat detection unit 60a and the heat detection unit 60b, each of the heat detection units 60a and 60b will be described as a heat detection unit 60. The heat detection unit 60 is connected so that the heat sensing unit 61 is located on the floor side of the board 50. Here, being located on the floor side means being located on the opposite side to the ceiling 200, and in FIG. 3, it refers to the underside 50b side of the board 50.

Figure 4 is a cross-sectional view showing the B-B cross section of Figure 3. Figure 5 is a cross-sectional view showing the C-C cross section of Figure 3. As shown in Figures 4 and 5, the main body 40 is provided below the base 20, and a battery 80 is housed between the base 20 and the main body part 41. A board 50 and a speaker 70 are provided on the underside 41b of the main body part 41, and a middle plate 90 is disposed below the board 50 and the speaker 70.

As shown in Figs. 1 and 2, the cover 30 is formed in a bottomed tubular shape, and has a cylindrical cover side portion 31, a disk-shaped cover bottom portion 32, and a slit portion 33 provided between the cover side portion 31 and the cover bottom portion 32. The cover side portion 31 surrounds the outer periphery of the main body 40. The cover bottom portion 32 is disposed opposite the lower surface 41b of the main body portion 41 on which the substrate 50, etc. are provided.

A vertical hole 32a is formed through the left and right sides of the cover bottom portion 32. A plurality of protruding contact prevention portions 32c are provided on the inner peripheral wall 32b of each vertical hole 32a, and the vertical hole 32a is formed, for example, in a cloverleaf shape. Each vertical hole 32a is located below each heat detection portion 60a, 60b, and the contact prevention portions 32c protect each heat detection portion 60a, 60b from contact with fingers, tools, etc. A vertical airflow flows into the circulation space SP through each vertical hole 32a. Here, the vertical airflow refers to an airflow that flows in a direction perpendicular to the surface of the ceiling 200. In addition, a buttonhole 32d is formed in the center of the cover bottom portion 32 to expose the push-in member 34 from the cover bottom portion 32.

The slit section 33 has a horizontal hole 33a that opens so as to extend in the circumferential direction of the cover 30, a plurality of main pillars 33b that extend in the vertical direction (arrow Z direction), a plurality of sub-pillars 33c that are provided between adjacent main pillars 33b, and a ring-shaped partition member 33d that divides the horizontal hole 33a. Each main pillar 33b supports the cover bottom surface section 32. Each sub-pillar 33c is thinner than the main pillar 33b and supports the partition member 33d together with the main pillar 33b. The horizontal hole 33a is divided into two stages by the ring-shaped partition member 33d. A horizontal airflow flows into the circulation space SP through the horizontal hole 33a. The airflow in the circulation space SP also flows out of the thermal alarm 100 through the horizontal hole 33a. Here, the horizontal airflow refers to an airflow that flows in a direction parallel to the surface of the ceiling 200.

As shown in Figures 3 and 4, the main body 41 has a board installation section 43 that forms a space in which the board 50 is housed, and a battery storage section 42 that forms a space in which the battery 80 is housed. The board installation section 43 is provided, for example, in the center of the main body 41. The battery storage section 42 is provided on the outer periphery side of the main body 41 relative to the board installation section 43. Specifically, the battery storage section 42 is provided in front of the center O1 of the main body 41 in the depth direction (arrow Y direction) and to the right of the center O1 of the main body 41 in the width direction (arrow X direction). Here, the center O1 of the main body 41 coincides with the center of the circulation space SP.

The board installation section 43 accommodates a rectangular board 50 with one corner cut out in an arc shape, with the cutout 50a positioned rearward and to the left of the center O1 of the main body section 41. The board installation section 43 is a wall section formed along the shape of the board 50 so as to protrude toward the cover bottom section 32, and the board 50 is accommodated so that the edge of the board 50 faces the board installation section 43.

A cylindrical battery 80 is housed in the battery housing 42 with its axis oriented in the width direction (arrow X direction). The battery housing 42 has a concave shape on the top surface 41a side of the main body 41 that conforms to the outer shape of the battery 80, which results in a raised bottom surface 41b side of the main body 41. The raised bottom surface 41b faces the cover bottom surface 32 with no gap between them, which divides the flow space SP.

A control circuit is provided on the board 50, and operating power for the control circuit is supplied from a battery 80. On the underside 50b of the board 50, there are mounted a switch 51 that detects when the push-in member 34 is pressed, a confirmation light 52, for example an LED, that turns on when a fire is detected, and a number of heat detectors 60a, 60b that detect the heat of hot air currents. As shown in Figures 4 and 5, the board 50 has pin holes 50c, 50d for mounting the heat detectors 60a, 60b, respectively.

The control circuit receives the output values of each heat detection unit 60a, 60b and determines the ambient temperature based on the output values. The control circuit outputs a fire signal to the speaker 70 when it determines that the ambient temperature is equal to or higher than a certain temperature based on at least one of the heat detection units 60. The control circuit may be configured to output a fire signal to the speaker 70 when there is a temperature change of equal to or higher than a set value in a short period of time.

As shown in Figs. 3 and 5, the speaker 70 has a circular shape and is installed on the underside 41b of the main body 41. The speaker 70 is located on the rear left side of the center O1 of the main body 41, and a part of it is located in the cutout 50a of the board 50. That is, as shown in Fig. 3, the battery accommodating section 42 is located on one side of an imaginary line Lv passing through the center O1 of the main body 41, and the speaker 70 is located on the imaginary line Lv with the battery accommodating section 42 and the center O1 in between. Here, the imaginary line Lv is a line that passes through the center O1 of the main body 41 and connects the battery accommodating section 42 and the speaker 70, and does not necessarily have to pass through the center of the battery accommodating section 42 and the center of the speaker 70.

The speaker 70 includes a diaphragm 71 that generates sound through vibration, and is electrically connected to the substrate 50. When a fire signal is input from the control circuit of the substrate 50 to the speaker 70, the speaker 70 vibrates the diaphragm 71 to generate sound.

Figure 6 is a cross-sectional view showing the A-A cross section of Figure 2. The push-in member 34 is an inspection button operated during an operational test of the heat alarm 100, and also functions as an indicator light in the event of a fire. The push-in member 34 is made of a translucent material such as acrylic resin, and has a button portion 34a exposed from a button hole 32d in the cover bottom portion 32, and a guide portion 34b extending toward the board 50. The tip of the guide portion 34b is located directly below the switch 51 and the confirmation light 52 provided on the board 50. The position at which the push-in member 34 is provided may be determined according to the position of the board 50 in the main body 40. During an operational test, when the button portion 34a is pressed by an operator or the like, the switch 51 is pressed and turned on by the guide portion 34b, and an operation for inspecting the function of the heat alarm 100 is started. On the other hand, when a fire is detected and the confirmation light 52 is turned on, the light projected from the confirmation light 52 is guided by the guide portion 34b, causing the button portion 34a to emit light.

Each of the heat detection units 60a, 60b has a heat-sensing unit 61 that detects heat, a rod-shaped lead portion 62 made of a lead wire, and a pin 63 attached to the base end of the lead portion 62. The heat-sensing unit 61 is made of, for example, a thermistor whose resistance changes in response to heat transmitted from the airflow, and converts the temperature change into an electrical signal for output.

The heat-sensing unit 61 is attached to the tip of the lead 62, and the heat-sensing unit 61 and the lead 62 are integrally coated. The pins 63 of each heat detection unit 60a, 60b are inserted into the pin holes 50c, 50d of the board 50, so that the base end of each lead 62 is connected to the board 50 and each heat-sensing unit 61 is electrically connected to the control circuit of the board 50. In other words, each heat detection unit 60a, 60b is connected to the board 50 so as to be connected to the floor side of the board 50. Note that each lead 62 may be connected to the board 50 by soldering.

As shown in Figs. 5 and 6, the middle plate 90 covers the substrate 50 and the speaker 70. A gap is provided between the middle plate 90 and the cover 30. The middle plate 90 has a guide hole 92 through which the guide portion 34b of the pushing member 34 passes, two detection holes 91 provided on the left and right of the guide hole 92, and a speaker hole 93 provided opposite the diaphragm 71 of the speaker 70. Each heat detection portion 60a, 60b passes through each detection hole 91. The speaker hole 93 is formed by a plurality of small holes provided radially from the center of the diaphragm 71. The sound generated by the speaker 70 passes through the speaker hole 93 and is transmitted to the outside via the circulation space SP and the cover 30.

As shown in FIG. 3, the two heat detection units 60a, 60b are arranged so that each heat sensing part 61 faces the outer periphery along the center line Lc, sandwiching the center O1 of the main body 41. Here, the center line Lc is a straight line passing through the center O1 of the main body 41, which is set separately from the virtual line Lv so as to avoid structures. In other words, each heat sensing part 61 of each heat detection unit 60a, 60b is arranged at a position off the virtual line Lv. Specifically, if the area formed by dividing the flow space SP in half by the virtual line Lv is defined as the first area R1 and the second area R2, the heat sensing part 61 of one heat detection unit 60a is located in the first area R1, and the heat sensing part 61 of the other heat detection unit 60b is located in the second area R2. By arranging this structure and the heat detection units 60a, 60b, areas through which air currents have difficulty passing are concentrated on the diagonal of the circulation space SP, and a space through which air currents can easily pass is secured in a position away from the imaginary line Lv, allowing the two heat sensing units 61 to detect the heat of the hot air currents in each area.

As shown in FIG. 6, each lead 62 of each heat detection unit 60a, 60b is attached at an angle to the substrate 50, and gradually approaches the cover bottom surface 32 from the base end to the tip end. Hereinafter, the angle formed by the lower surface 50b of the substrate 50 and the lead 62 is referred to as the inclination angle θ. Each lead 62 has a length such that the tip end is positioned outside the outer periphery of the substrate 50.

The position of the heat-sensing part 61 provided at the tip of the lead part 62 will be described in detail. In the height direction (arrow Z direction), each heat-sensing part 61 is located facing the horizontal hole 33a and is located between the board 50 and the cover bottom part 32. Each heat-sensing part 61 is also located on the outer periphery side of the outer edge 50e of the board 50, and is located between the outer edge 50e of the board 50 and the cover side part 31. In particular, the heat-sensing part 61 of the heat detection part 60b is located outside the battery storage part 42 in the width direction (arrow X direction) as shown in Figures 3 and 4, and is easily hit by the hot air flow F2 described later.

The configuration of each heat detection unit 60a, 60b ensures that the distance between each heat sensing unit 61 and the main body 40 is more than a certain distance, so that the heat of the airflow passing through the heat sensing unit 61 is prevented from being absorbed by the main body 40, and each heat sensing unit 61 can receive heat with high efficiency. In addition, each heat sensing unit 61 is closer to the cover 30 than the base end of the lead unit 62, and the two heat sensing units 61 are arranged on the center line Lc with the center O1 in between, so that no matter what direction the airflow flows into the cover 30 from, there is no particular delay in detection. In other words, directivity can be reduced. Furthermore, the airflow flowing in from the vertical hole 32a flows not only through the horizontal hole 33a but also through the space above each heat sensing unit 61, so the flow of the airflow is improved and the amount of airflow flowing in from the vertical hole 32a can be increased.

When each heat-sensing part 61 is disposed outside the outer periphery of the substrate 50, the inclination angle θ of the lead part 62 may be 0°. Even in this case, each heat-sensing part 61 is spaced apart from the substrate 50 and the main body part 41, and a space is provided above each heat-sensing part 61, so that good heat receiving characteristics can be obtained.

The flow of air in the event of a fire will be explained with reference to Figure 1. When a fire breaks out in the monitored space, a vertical airflow is generated from the source of the fire toward the ceiling 200, and after reaching the ceiling 200, the direction of the airflow becomes parallel to the ceiling 200 and flows along the ceiling 200 as a horizontal airflow. If the source of the fire is directly below the heat alarm 100, the vertical airflow reaches the cover bottom portion 32. Also, if the source of the fire is not directly below the heat alarm 100, all of the vertical airflow rising from the source of the fire reaches the ceiling 200, flows along the ceiling 200 as a horizontal airflow, and reaches the heat alarm 100.

Next, the flow of the horizontal air current that reaches the slit section 33 of the heat alarm 100 will be explained with reference to Figure 3. The position and direction into which the horizontal air current flows will differ depending on the location of the fire source. First, the case where the fire source is located in front of the heat alarm 100 will be explained using heat air currents F1 to F3.

The hot air flow F1 that reaches the slit section 33 at the center of the front flows into the housing 10 through the horizontal hole 33a, flows along the battery housing section 42, transfers heat to the heat detection section 60a, and flows out of the housing 10 through the horizontal hole 33a. The hot air flow F2 that reaches the slit section 33 at a position to the right of the hot air flow F1 flows into the housing 10 through the horizontal hole 33a, travels along the right side surface 42a of the battery housing section 42, transfers heat to the heat-sensing section 61 of the heat detection section 60b located outside the right side surface 42a, and flows out of the horizontal hole 33a. The hot air flow F3 that reaches the slit section 33 at the left front position flows into the housing 10 through the horizontal hole 33a and blows through the space to the left of the battery housing section 42. At this time, the hot air flow F3 passes through the heat-sensing section 61 of the heat detection section 60a immediately after entering the housing 10, so that heat is efficiently transferred from the hot air flow F3 to the heat detection section 60a.

In this way, even if there is a structure such as the battery storage section 42, the hot air flow F2 passes through the heat detection section 60b, and the hot air flow F1 and the hot air flow F3 pass through the heat detection section 60a. Therefore, if there is a source of fire in front of the heat alarm 100, heat is quickly detected by at least one of the two heat detection sections 60a, 60b, and the heat alarm 100 can alert the fire without delay.

For example, in the case of a hot air current flowing from a direction such as hot air current F3, it is effective on heat detection unit 60a, but is unlikely to hit heat detection unit 60b due to the presence of battery storage unit 42. However, since heat detection units 60a and 60b are positioned symmetrically about center O1 and are positioned on the outer periphery to avoid structures, at least one of them can efficiently detect heat no matter from which direction the hot air current flows in a 360° range.

Next, the case where the source of fire is on the rear side of the thermal alarm 100 will be explained using hot air flows F4 to F6. Hot air flow F4 that reaches the slit section 33 on the rear left side flows into the housing 10 through the horizontal hole 33a and passes through the gap between the middle plate 90 and the cover bottom section 32, which are located below the speaker 70. At this time, the hot air flow F4 flows in a curved manner into the space to the left of the speaker 70, where the space is wide, and transfers heat to the heat-sensing section 61 of the heat detection section 60a before flowing out of the horizontal hole 33a. Hot air flow F5 that reaches the slit section 33 at the rear center position bends from the narrow space between the speaker 70 and the cover bottom section 32 to the wide space between the middle plate 90 and the cover bottom section 32, or to the even wider space on the right side, and transfers heat to the heat detection section 60b before flowing out of the housing 10. This flow is also due to the influence of the battery storage section 42 on the traveling direction side. The hot air current F6 that reaches the slit section 33 on the rear right side flows into the housing 10 through the horizontal hole 33a and blows through the space to the right of the speaker 70. At this time, the hot air current F6 passes through the heat-sensing section 61 of the heat detection section 60b immediately after flowing into the housing 10, so heat is efficiently transferred from the hot air current F6 to the heat detection section 60b.

In this way, even if there is a structure such as a speaker 70, the hot air current F4 passes through the heat detection unit 60a, and the hot air currents F5 and F6 pass through the heat detection unit 60b. Therefore, even if the source of the fire is behind the heat alarm 100, heat is quickly detected by at least one of the two heat detection units 60a, 60b, allowing the heat alarm 100 to alert the fire without delay.

In addition, if the source of the fire is to the left of the heat alarm 100, the horizontal air current reaches a position to the left of the slit section 33 and flows into the housing 10 through the horizontal hole 33a, and immediately transfers heat to the heat detection unit 60a. Similarly, if the source of the fire is to the right of the heat alarm 100, the horizontal air current reaches a position to the right of the slit section 33 and flows into the housing 10 through the horizontal hole 33a, and immediately transfers heat to the heat detection unit 60b. In this way, the heat alarm 100 can quickly detect a fire regardless of the location of the source of the fire.

Next, the flow of the vertical air current when the source of the fire is directly below the heat alarm 100 will be described with reference to FIG. 6. The hot air current F8 shown in FIG. 6 represents the flow of the vertical air current that reaches the vertical holes 32a of the cover bottom surface portion 32 when the source of the fire is directly below the heat alarm 100. The hot air current F8 flows into the housing 10 from each vertical hole 32a, and the hot air current F8 that flows in directly hits each heat-sensing portion 61, transmitting heat. Then, a part F8a of the hot air current F8 flows out of the housing 10 through the horizontal hole 33a. The remaining part F8b of the hot air current F8 flows into the space provided between the heat-sensing portion 61 and the main body portion 41, hits the lower surface 41b of the main body portion 41, is guided to the slit portion 33, and flows out from the horizontal hole 33a. In this way, the hot air current F8 can proceed further after passing through the heat-sensing portion 61, and the inflow of the hot air current from each vertical hole 32a is promoted. In addition, because the heat-sensing part 61 and the main body part 41 are far apart, the heat of the hot air flow is less likely to be absorbed by the main body part 41, and the heat-sensing part 61 is more likely to receive the heat.

On the other hand, the hot air current that arrives outside each vertical hole 32a flows along the cover bottom portion 32, with a portion flowing into the cover 30 through the vertical holes 32a, and the remaining portion flowing through the outer surface of the cover bottom portion 32 to the ceiling 200.

As described above, in the first embodiment, each heat detection unit 60a, 60b is connected to the substrate 50 so that the heat sensing unit 61 is located on the outer periphery side of the main body 41 rather than the position where it is connected to the substrate 50. The two heat sensing units 61 are also arranged on a line segment passing through the center O1 of the main body 41 so as to sandwich the center O1. This allows the hot air current to pass through one of the heat sensing units 61 even when the heat detection units 60a, 60b are provided inside the cover 30 before the heat of the hot air current is absorbed by the main body 41 and the substrate 50, etc., and the temperature drops. In addition, the hot air current can be directed to the heat sensing unit 61 without being obstructed by the lead portion 62 of the heat detection unit 60. Therefore, it is possible to obtain good heat receiving characteristics while omitting a protector and making the thermal alarm 100 thinner.

In general, the type and arrangement of the structures housed within the housing 10 differ depending on the model, etc. Therefore, simply installing the heat detection unit within the cover 30 will result in high directionality depending on the arrangement of the structures. On the other hand, the heat alarm 100 can reduce the bias in sensitivity caused by the location of the fire source by devising the arrangement of the two heat-sensing units 61, and achieve good heat receiving characteristics.

The heat-sensing part 61 of each heat detection part 60a, 60b is disposed between the main body part 41 and the cover bottom part 32 facing the main body part 41, and is provided so that the heat detection part 60 protrudes toward the floor side of the board. In other words, the heat detection part 60 provided on the board inside the housing 10 is provided so that it protrudes toward the cover side on the floor side, not toward the main body side on the ceiling side. This allows the heat-sensing part 61 to be separated from the main body part 41 and the board 50 and to be brought closer to the horizontal hole 33a and vertical hole 32a, which are the circulation holes. Therefore, the hot air flow that flows into the circulation space SP can be passed through the heat-sensing part 61 as soon as possible, so that each heat detection part 60a, 60b can detect the heat of the air flow quickly and efficiently.

The heat-sensing part 61 of each heat detection part 60a, 60b is disposed outside the outer edge 50e of the substrate 50. As a result, there is no substrate 50 above the heat-sensing part 61, and a space is provided between the heat-sensing part 61 and the main body part 41, so that the temperature drop of the hot air flow caused by the substrate 50 can be suppressed and the amount of heat in the heat-sensing part 61 can be secured. Furthermore, when the vertical hole 32a is provided, the air flow that has passed through the heat-sensing part 61 can penetrate further up, making it easier for the air flow to pass through the housing 10 and promoting the outflow and inflow of the hot air flow. Therefore, compared to when the substrate 50 is provided above the heat-sensing part 61, the amount of hot air flow passing through the heat-sensing part 61 is greater, and good heat receiving characteristics can be obtained.

Embodiment 2.
Fig. 7 is an explanatory diagram showing the configuration inside the housing 310 of a thermal alarm 300 according to embodiment 2. Fig. 8 is a cross-sectional view showing the D-D cross section of Fig. 7. Fig. 8 shows the main body 340 with the middle plate 390 attached. In embodiment 2, the layout of the structures, the shape of the main body 340, the shape of the middle plate 390, the shape of the board 350, and the layout of the heat detection units 60a, 60b are different from those in embodiment 1. Hereinafter, in embodiment 2, the same components as in embodiment 1 are denoted by the same reference numerals, and description thereof will be omitted.

The battery accommodating section 342 is provided to extend forward from the center O1 of the main body section 341, and the battery 80 is accommodated in the battery accommodating section 342 with the axial direction being the depth direction (arrow Y direction). The speaker 70 is disposed on the left side of the battery accommodating section 342. The board 350 is disposed below the main body section 341, spanning from the rear side of the speaker 70 and battery accommodating section 342 to the right side of the battery accommodating section 342.

The middle plate 390 is provided below the main body 341 so as to cover the substrate 350 and the speaker 70. The right side of the middle plate 390 extends forward along the right side surface 342a of the battery housing section 342 to the outer periphery of the main body 341. A flow space SP is formed between the cover 30 and the main body 341 on which the middle plate 390 is provided. By providing the middle plate 390, it is possible to reduce the unevenness of the flow space SP and reduce resistance.

The middle plate 390 is also formed with a guide hole 392 through which the guide portion 34b of the pushing member 34 passes, two detection holes 391, and a speaker hole 393 that faces the diaphragm 71 of the speaker 70. The two detection holes 391 are provided at positions that face the base ends of the two heat detection units 60a, 60b installed on the left and right sides of the substrate 350.

The heat detection units 60a, 60b are electrically connected and fixed to the board 50 by soldering the base end of the lead portion 62 to the board 350. The lead portion 62 is inserted into the detection hole 391 of the middle plate 390, and the heat sensing unit 61 is disposed between the middle plate 390 and the cover bottom portion 32. The heat detection units 60 are provided on the left and right sides of the board 350, which is disposed rearward of the center O1 of the main body portion 341, and each lead portion 62 is fixed to the board 350 so as to extend forward and toward the outer periphery, and the two heat sensing units 61 are disposed on the center line Lc with the center O1 of the main body portion 41 in between.

The shape of the substrate 350 is formed so that the outer periphery is recessed at the position of the heat-sensing portion 61. As a result, even in the second embodiment, each heat-sensing portion 61 is positioned on the outer periphery side of the outer edge 350e of the substrate 350, between the outer edge 350e of the substrate 350 and the cover side portion 31.

The length Dd of the lead portion 62 in the heat detection unit 60 is shorter than the diameter Ds of the speaker 70. The heat sensing portion 61 is located on the outer periphery of the body portion 341 by 80% or more of the diameter. With this configuration, the heat sensing portion 61 is placed near the slit portion 33 to easily receive heat, and the structure protruding from the body portion 341 into the flow space SP is reduced to facilitate the passage of hot air. In FIG. 7, the lead portion 62 of the heat detection unit 60 is arranged so as to be in contact with the speaker 70, but the lead portion 62 may be arranged in any manner as long as the heat sensing portion 61 is located on the diameter of the body.

Next, the flow of the horizontal air current that reaches the thermal alarm 300 will be described with reference to Figure 7. If there is a fire source on the front side of the thermal alarm 300, the hot air current F12 that reaches the slit section 33 at the front left position flows into the housing 310 through the horizontal hole 33a, transfers heat to the heat detection section 60a, and flows out of the housing 310 through the horizontal hole 33a. The hot air current F15 that reaches the slit section 33 at the front right position flows into the housing 310 through the horizontal hole 33a, transfers heat to the heat detection section 60b, and flows out of the housing 310 through the horizontal hole 33a.

If there is a fire source on the rear side of the thermal alarm 300, the hot air flow F13 that reaches the slit section 33 at the rear left position flows into the housing 310 through the horizontal hole 33a, transfers heat to the heat detection section 60a, and flows out of the housing 310 through the horizontal hole 33a. The hot air flow F16 that reaches the slit section 33 at the rear right position flows into the housing 310 through the horizontal hole 33a, transfers heat to the heat detection section 60b, and flows out of the housing 310 through the horizontal hole 33a.

Here, the hot air currents F12, F15 flowing in from the front and the hot air currents F13, F16 flowing in from the rear travel approximately the same distance from when they enter the housing 310 until they reach the heat-sensing unit 61. For example, if the line connecting the two heat-sensing units 61 is located at the rear and does not pass through the center O1, the distance traveled from when the source of the fire is at the front until it reaches the heat-sensing unit 61 will be longer than when the source of the fire is at the rear, and detection may be delayed. On the other hand, in a configuration such as the heat alarm 300 in which the two heat-sensing units 61 are arranged on the center line Lc with the center O1 between them, there is no significant difference in the time it takes to detect heat between when the source of the fire is at the front and when it is at the rear.

If the source of the fire is on the left side of the thermal alarm 300, the hot air current F11 that reaches the slit section 33 at the left side flows into the housing 310 from the horizontal hole 33a, immediately passes through the heat detection section 60a, bends backwards when it hits the battery storage section 342, and flows out from the horizontal hole 33a. The hot air current F11 does not pass through the heat-sensing section 61 of the heat detection section 60b, but passes through the heat detection section 60a immediately after flowing into the housing 310, so heat is efficiently transferred from the hot air current F11 to the heat detection section 60a.

If the source of the fire is on the right side of the thermal alarm 300, the hot air flow F14 hits the battery housing 342 and bends, so it does not pass through the heat-sensing part 61 of the heat detection part 60a, but it flows into the housing 310 and immediately passes through the heat detection part 60b, so the heat detection part 60b can efficiently detect the heat from the hot air flow F14.

When hot air current F17 flows from the diagonally front right side of the main body toward the center, the flow is blocked by the battery storage section 342, so heat is not easily transmitted to the heat detection section 60a. However, since heat detection section 60b is located symmetrically on either side of heat detection section 60a and center O1, heat can be detected efficiently by heat detection section 60b. When hot air current F18 flows from the diagonally rear left side toward the center, heat detection section 60a is located near horizontal hole 33a, so heat can be detected efficiently. As a result, by combining the two heat detection sections 60a and 60b, it is possible to detect hot air currents from any direction in a 360° range.

As described above, in the second embodiment, each heat detection unit 60a, 60b is connected to the substrate 50 so that the heat sensing unit 61 is located closer to the outer periphery of the main body 41 than the position where it is connected to the substrate 50, and the two heat sensing units 61 are arranged on the center line Lc so as to sandwich the center O1. As a result, in the heat alarm 300 of the second embodiment, as in the first embodiment, it is possible to obtain good heat receiving characteristics while making the device thin.

The embodiment of the present invention is not limited to the above embodiment, and various modifications can be made. For example, the number of heat detection units 60 may be three or more. Furthermore, the first structure and the second structure are not limited to the battery storage unit 42 and the speaker 70. For example, the first structure may be defined as the structure that occupies the largest volume in the space formed between the main body 40 and the cover 30, and the second structure may be defined as the structure that occupies the second largest volume after the first structure.

Next, the vertical hole will be described. The heat-sensing part 61 above the vertical hole 32a is visible from the front as shown in FIG. 2, so it is subject to design restrictions (for example, the vertical holes are arranged symmetrically, the heat-sensing part 61 must be placed at the center of the vertical hole 32a, etc.). However, if good heat-receiving characteristics are obtained, the vertical hole 32a does not necessarily have to be provided. Alternatively, although the embodiment has been described in which the vertical hole 32a is provided at the bottom of each of the heat-sensing parts 61, for example, in a heat alarm using two heat detection parts 60, the vertical hole 32a may be provided only in the heat-sensing part 61 of one heat detection part 60a. In other words, the part of the cover facing the heat-sensing part 61 of the other heat detection part 60b may be closed without making a hole, so that no vertical hole is provided. In this way, the heat-sensing part 61 of the heat detection part 60b on the side where the vertical hole is not provided is not visible from the outside, so there are no design restrictions as described above, and the installation position of the heat detection part 60 on the board 50 can be freely designed. In other words, since there is no vertical hole 32a, the position of the heat-sensing part 61 of the heat detection unit 60b does not have to be symmetrical on the diameter of the main body 40. For example, the heat-sensing part 61 of the heat detection unit 60a facing the vertical hole 32a may be positioned further to the outer periphery of the main body 41 to increase the heat receiving efficiency.

The shape of the vertical hole 32a is not limited to the shape shown in FIG. 2, and may be circular or slit-shaped. When the vertical hole is slit-shaped, its length is approximately the same as the length Dd of the lead portion of the heat detection unit 60, and its width can be approximately 5 mm to prevent the intrusion of fingers. The vertical hole may be of any shape, so long as it allows sufficient vertical airflow to flow into the circulation space SP, and the heat-sensing unit cannot be easily touched by fingers, etc., taking into account the shape and size of the hole, and the number of holes can also be freely determined according to the number of heat detection units 60.

Now, let us consider the location of the heat detection unit 60. The heat-sensing unit 61 formed at the tip of the heat detection unit 60 is desirably provided on the outer periphery of the main body 40, as close as possible to the circulation holes. The closer to the outer periphery of the main body 40 it is, the more it will come into contact with hot air currents at higher temperatures, improving heat reception efficiency. As mentioned above, there are horizontal and vertical hot air currents that enter the main body 40, so the heat-sensing unit 61 may be positioned at approximately equal distances from both the horizontal and vertical holes 33a and 32a.

In the above embodiment, a heat-type fire alarm equipped with a battery 80 and a speaker 70 has been described, but the present invention may also be applied to a heat-type detector that does not have a battery 80 or a speaker 70.

10, 310 housing, 20 base, 30 cover, 31 cover side portion, 32 cover bottom portion, 32a vertical hole, 32b inner wall, 32c contact prevention portion, 32d button hole, 33 slit portion, 33a horizontal hole, 33b main support, 33c sub-support, 33d partition member, 34 push-in member, 34a button portion, 34b guide portion, 40, 340 main body, 41, 341 main body portion, 41a main body upper surface, 41b main body lower surface, 42, 342 battery storage portion, 42a, 342a right side surface, 43 board installation portion, 50, 350 board, 50a cutout portion, 50b (board) lower surface, 50c pin hole, 50d pin hole, 50e, 350e outer edge, 51 Switch, 52, confirmation light, 60, 60a, 60b, heat detection unit, 61, heat sensing unit, 62, lead, 63, pin, 70, speaker, 71, diaphragm, 80, battery, 90, 390, middle plate, 91, 391, detection hole, 92, 392, guide hole, 93, 393, speaker hole, 100, 300, heat alarm, 200, ceiling, Dd, length of lead, Ds, diameter of speaker, F1, F2, F3, F4, F5, F6, F7, F8, F11, F12, F13, F14, F15, F16, F17, F18, hot air flow, Lc, center line, Lv, virtual line, O1, center (of main body), R1, first area, R2, second area, SP, flow space, θ, inclination angle.

Claims (2)

A main body portion,
A cover having a flow hole and forming a flow space between the cover and the main body;
a substrate provided on the main body portion so as to face the cover and having a circuit;
two heat detection units each having a heat sensing portion at a tip thereof and configured to detect heat of the airflow flowing into the flow space through the flow hole, the two heat detection units being electrically connected to the substrate;
a middle plate that is provided in the main body portion so as to cover the substrate and that divides the flow space into a space in which the substrate is disposed and a space connected to the flow hole, the middle plate having detection holes through which the two heat detection units are passed;
Equipped with
the cover has a bottom surface facing the main body portion on which the substrate is provided,
The bottom surface is provided with a vertical hole, which is the circulation hole and through which the vertical airflow flows,
each of the heat detection units is connected to the substrate such that the heat sensing unit is located closer to the outer periphery of the main body than a position where the heat detection unit is connected to the substrate, and the heat sensing unit is located closer to the bottom surface of the cover than the substrate and the midplate;
The heat-sensing parts of the two heat detection units are arranged on a line segment passing through the center of the main body so as to sandwich the center of the main body,
A thermal alarm, characterized in that the heat-sensing portion of each of the heat detection units is disposed outside an outer edge of the substrate. The bottom surface of the cover is provided with two vertical holes facing the heat sensing parts of the heat detection parts,
The mid-plate has a mid-plate sidewall portion extending toward the main body portion so as to cover the outer edge of the base plate,
The mid-plate side wall portion and the heat-sensing portion of each of the heat detection units are arranged such that, in a vertical cross section passing through the line segment along which the heat-sensing portions of the two heat detection units are arranged, the heat-sensing portion of each of the heat detection units is located closer to the outer periphery of the main body portion than the mid-plate side wall portion.
2. The thermal alarm of claim 1.

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