JP7649900B2 - Heat detector - Google Patents

Description

The present invention relates to fire detectors, and in particular to technology that is effective when applied to heat detectors that use thermistors as heat-sensitive elements (sensors).

A heat detector using a thermistor is generally configured to detect the occurrence of a fire by disposing a thermistor as a heat-sensitive element in the center of a dome-shaped housing, and attaching the housing to the ceiling surface of a building so that the thermistor faces downward. Some fire detectors are also provided with an operation indicator light on the cover that can be turned on so that it can be visually determined from the outside that the detector has detected a fire.
Conventionally, most fire detectors have an operation indicator light that is a point-emitting type LED installed on the surface of the detector. In such cases, the point-emitting indicator light is generally installed away from the center of the detector, but this type of operation indicator light has a directional visibility. Therefore, fire detectors installed on the ceiling must be installed so that the operation indicator light faces the entrance side in a position that can be seen when the entrance door is opened, for example, so that it is easy to see when looking up from below to check the status of the operation indicator light. Otherwise, it will be difficult to check the operation of the detector when a fire is detected.

Therefore, in order to eliminate the directionality of the operation indicator light, some detectors have multiple point-type LEDs on the cover of the detector, or a point-type LED is installed on the top of the detector, or an indicator light that lights up in a ring shape on the flat part of the detector cover.
On the other hand, in the manufacturing process of a general heat detector, after the thermal element is soldered to the electronic board, when the electronic board is attached to the detector housing, the element is inserted into an opening in the housing that is just the right size for the diameter of the thermal element, which makes assembly difficult. In addition, since there is no structure to protect the thermal element when mounted on the electronic board, there is a possibility that it may be damaged during assembly, and there is also the issue that skilled assembly is required.

In addition, examples of heat detectors having a structure in which a thermistor is mounted on a printed wiring board that constitutes a fire detection circuit and an insertion hole through which the thermistor protrudes is formed in the center of a cover that covers the board are described in Patent Documents 1 and 2, for example.
Furthermore, a sensor having a ring-shaped indicator lamp that lights up on the flat portion of the cover is described in, for example, Japanese Patent Application Laid-Open No. 2003-233696.
Furthermore, Patent Document 4 describes as embodiment 2 a heat detector in which a protector covering the head of the thermistor is made of a translucent resin material and a confirmation light is disposed at the base of the protector to illuminate the entire protector.

Japanese Patent Application Publication No. 05-266377 Japanese Patent Application Publication No. 05-225459 JP 2001-14570 A JP 2003-36488 A

In the case of heat detectors, it is difficult to install an operation indicator light on the top of the detector because the heat-sensitive element is located there, and if a ring-shaped indicator light is placed on the detector cover as in the detector described in Patent Document 3, there are issues such as increased costs due to the increased number of parts and difficulty in miniaturization. In particular, with heat detectors, the electronic boards have become smaller due to the miniaturization of electronic components, and as a result the detector housings have also become smaller, so it is difficult to arrange a ring-shaped operation indicator light in the structure described in Patent Document 3.

In addition, heat detectors often use thermistors as the heat-sensing elements, but thermistors are thin and delicate elements that are supported by soldering two lead terminals of the element to the electronic circuit board, which can lead to damage during assembly. Furthermore, the thermistor is mounted upright on the electronic circuit board and assembled by inserting the heat-sensing element into an opening on the surface of the detector's main body, but a small opening makes assembly difficult, while a larger opening allows dust and moisture to easily get inside the detector, which can have a detrimental effect on the electronic circuit.

Patent Document 4 describes a heat detector with a structure in which a mortar-shaped support member is provided at the base of the thermistor and the head of the thermistor is covered with a protector. As mentioned above, this heat detector has a protector made of a translucent resin material, and a confirmation light is provided at the base of the protector to guide light throughout the protector and cause it to emit light. However, there is no suggestion as to how the light will circulate, and the use of two light-emitting elements poses the problem that good light emission cannot be achieved with this method alone.

The present invention has been made in response to the above-mentioned problems, and its object is to improve the ease of assembly of a heat detector that uses a thermistor as a thermal element, as well as to improve the visibility of the operation indicator light.
Another object of the present invention is to provide a heat detector which can be made compact and has a reduced number of parts, thereby reducing costs.

In order to achieve the above object, the present invention provides
A heat detector in which a circuit board on which a heat-sensitive element and components constituting a detection circuit are mounted is housed inside a housing consisting of a main body case and a main body cover that covers the open side of the main body case,
an element support member made of a light-transmitting material, the element support member having an insertion cylindrical portion with an inner diameter larger than a diameter of the heat-sensitive element and a cone-shaped tapered portion that spreads outwardly downward from a lower end of the insertion cylindrical portion, the insertion cylindrical portion being attached to the circuit board such that the insertion cylindrical portion is positioned around the heat-sensitive element;
The tapered portion of the element support member is configured so as to be illuminated entirely by light emitted from a light emitting element mounted on the circuit board.

In a heat detector having the above configuration, the element support member has a cylindrical insertion portion with an inner diameter larger than the diameter of the heat-sensitive element and a cone-shaped tapered portion, making it easier to insert the heat-sensitive element mounted on the circuit board and improving assembly. In addition, because the entire tapered portion of the element support member is illuminated, the light emitted from the tapered portion can be seen from any direction of 360°, improving visibility. Furthermore, when a light-emitting element is used as the light source for the operation indication, the element support member also serves as an operation indicator light, making it possible to miniaturize the detector and reduce the number of parts, thereby cutting costs.

Here, it is preferable that the main body cover has an opening formed at a position corresponding to the heat-sensitive element, and includes a plurality of straightening fins forming an inlet through which outside air can flow in,
A head member is provided to define a space into which the tip of the heat-sensitive element faces and to cover the opening.

Furthermore, preferably, the element support member is provided with a flange portion extending horizontally outward from the lower end of the tapered portion, and the flange portion is provided with a light introducing portion capable of introducing light from a light-emitting element mounted on the circuit board, and a light reflecting portion that reflects the light introduced from the light introducing portion toward the tapered portion.
According to this configuration, a flange portion provided at the lower end of the bowl-shaped tapered portion made of a light-transmitting material is provided with a light introducing portion capable of introducing light from a light-emitting element mounted on a circuit board, and a light reflecting portion that reflects the light introduced from the light introducing portion toward the tapered portion, so that the entire tapered portion can be made to glow, thereby improving visibility.

Also, preferably, the element support member includes a flange portion extending horizontally outward from a lower end of the tapered portion,
a light output portion protruding downward along a circumferential direction is formed on a peripheral edge portion of the flange portion of the element support member,
The body cover is configured to have a slit formed therein, into which the light exit portion fits and which is exposed on the surface of the body cover.
The light exit portion is formed, for example, as an annular rib. According to the above-mentioned configuration, the entire tapered portion and the light exit portion formed along the circumferential direction can be illuminated, so that the light emitting area can be increased and the visibility can be further improved.

Also, preferably, the element support member includes a flange portion extending horizontally outward from a lower end of the tapered portion,
The flange portion of the element support member is formed with a plurality of convex portions arranged in a circumferential direction, and the main body cover is formed with a plurality of windows into which the convex portions fit and which are exposed on the surface of the main body cover.

The above configuration allows the entire tapered portion and the multiple convex portions arranged in the circumferential direction formed on the flange portion of the element support member to be illuminated, thereby increasing the light-emitting area and further improving visibility.

The heat detector of the present invention can improve the ease of assembly and visibility of the operation indicator light in a heat detector that uses a thermistor as a heat-sensitive element. The present invention also has the effect of realizing a heat detector that can be made smaller and has a reduced number of parts, thereby reducing costs.

1 is a front cross-sectional explanatory view showing a first embodiment of a heat detector according to the present invention; 1A is a front cross-sectional explanatory view showing a specific example of an element support member constituting the heat detector of the first embodiment, and FIG. FIG. 5 is a front cross-sectional explanatory view showing a second embodiment of a heat detector according to the present invention. 13A is a front cross-sectional explanatory view showing a specific example of an element support member constituting a heat detector according to a second embodiment, and FIG. 10A and 10B are explanatory front sectional views showing an example of a configuration of an element support member constituting a heat detector according to a modified example, and FIG. 13 is a front cross-sectional view illustrating a modified example of the element support member. FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a heat detector according to the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is an explanatory front sectional view of a heat detector according to a first embodiment, and FIG. 2 shows a specific example of an element support constituting the heat detector according to the first embodiment.
The heat detector 10 of this embodiment is a detector that uses a thermistor 11 as a heat-sensitive element and can detect a fire by detecting the change in electrical resistance that occurs when air heated by the heat generated by a fire comes into contact with the thermistor 11, and is configured for use by being installed on the ceiling surface of a building with the tip of the thermistor 11 facing downward.

As shown in Fig. 1, the heat detector 10 of this embodiment comprises a cylindrical main case 12 with a bottom that has a recess for accommodating heat-sensing components and can be inserted into an installation opening provided in the ceiling surface of a building, and a main case cover 13 that has a protector part 13A in the center that covers the tip of the thermistor 11 and is connected to the main case 12 so as to cover the opening on the lower side of the main case 12, and the main case 12 and the main case cover 13 form a housing with an internal storage space. Although not shown, a terminal block is provided on the upper part of the main case 12 to electrically connect the wiring arranged on the underside of the ceiling to the internal circuit board.

The heat detector 10 also includes a circuit board 14 that is accommodated in the accommodation recess of the main body case 12 and fixed to a boss portion at the bottom of the main body case 12 by a screw (not shown), the thermistor 11 is mounted at approximately the center of the circuit board 14, and an inverted cone-shaped element support member 15 is provided that has a cylindrical portion 15a through which the thermistor 11 can be inserted and is joined to the surface of the circuit board 14 with the base of the thermistor 11 inserted. The thermistor 11 is mounted on the circuit board 14, and resin 16 is filled and solidified in the upper cylindrical portion 15a of the element support member 15 through which the base of the thermistor 11 is inserted, thereby supporting the base of the thermistor 11.

The body cover 13 has a body portion which is generally in the shape of a flat disk, with an opening formed in the center of the body portion, and a protector portion 13A provided so as to cover the opening from below.
The circuit board 14 is composed of a printed wiring board on whose top and bottom surfaces electronic components such as resistors, capacitors, and ICs (semiconductor integrated circuits) that constitute an electronic circuit for fire detection are mounted, and approximately in the center of the circuit board 14, the tips of the two lead terminals of the thermistor 11 penetrate the circuit board 14 and protrude from the top surface, and are connected to the circuit board 14 by soldering or the like.
Furthermore, a light emitting element 17 such as an LED (light emitting diode) is surface-mounted on a predetermined portion of the circuit board 14 .

The element support member 15 is made of a translucent material such as polycarbonate resin, and as shown in FIG. 2(A), it has a cylindrical portion 15a for inserting the thermistor 11, a tapered portion 15b that expands diagonally downward from the cylindrical portion 15a, a flange portion 15c that extends horizontally outward from the lower end of the tapered portion 15b, and a plurality of (e.g., three) mounting locking pieces 15d that stand upward from the outer circumferential surface of the tapered portion 15b and have outward claws at their tips. In addition, at the corresponding portion of the circuit board 14, engagement holes through which the claws of the locking pieces 15d can be inserted are formed in a number corresponding to the number of the locking pieces 15d, and the element support member 15 is attached to the circuit board 14 by the locking pieces 15d. Note that, for convenience of illustration, only one of the plurality (three) locking pieces 15d is shown in FIG. 1 and FIG. 2. However, there may be only one locking piece 15d.

As described above, the element support member 15 has a mortar-shaped tapered portion 15b, which allows for easy assembly when mounting the element support member 15 on the circuit board 14 on which the thermistor 11 is mounted. After mounting the element support member 15 on the circuit board 14 by inserting the thermistor 11 through the cylindrical portion 15a, resin can be easily filled into the cylindrical portion 15a for inserting the thermistor by aligning the nozzle of a dispenser to face the inside of the tapered portion 15b.

Furthermore, a step (recess) 13b is provided on the upper surface of the opening edge of the disk-shaped main body part of the body cover 13, and the step 13b is configured to be joined to the lower surface of the flange 15c of the element support member 15. A film or layer with good light reflectance, such as aluminum, may be formed on the inner surface of the step 13b of the body cover 13 to which the flange 15c is joined.
Furthermore, a cylindrical light guiding portion 15e is provided on flange portion 15c of element support member 15 in correspondence with the position of light emitting element 17 mounted on circuit board 14, and a light reflecting portion 15f is provided on a surface portion (the lower surface portion in the figure) corresponding to light guiding portion 15e. The end face of light guiding portion 15e, i.e., the surface facing light emitting element 17, is formed in a concave shape so as to be able to sufficiently introduce light from light emitting element 17.

As shown in FIG. 2(A), the light reflecting portion 15f has an inclined surface perpendicular to the tapered portion 15b when cut vertically, and is a V-shaped recess (groove) when viewed from the direction of the arrow C in FIG. 2(B). It is formed to reflect the light guided from the light guiding portion 15e in the inclined direction of the tapered portion 15b shown in FIG. 2(A) and in the circumferential direction of the flange portion 15c shown in FIG. 2(B). The surface of the element support member 15 on the circuit board side may be microfabricated with a number of thin linear grooves, so that the entire inner surface of the tapered portion 15b emits light more brightly by reflecting the light that hits the grooves. In addition, by microfabricating the element support member 15, it becomes like frosted glass, which has the effect of making it impossible to see inside the sensor from the outside. In addition, fine particles that diffusely reflect light may be mixed into the material forming the element support member 15.

The protector part 13A shown in FIG. 1, which is formed integrally with the main body cover 13, includes a plurality of (e.g., six) straightening fins 13c that spread radially in a plan view, and a disk-shaped head cover 13d that connects the tips (lower ends in FIG. 1) of these straightening fins 13c. The tip of the thermistor 11 is located in the space surrounded by the plurality of straightening fins 13c and the head cover 13d, and airflow passes between each straightening fin 13c. The head cover 13d has a smaller diameter than the diameter of the base (upper part in the figure) of the protector part 13A, and is formed to have an inverted trapezoidal shape when the sensor is viewed from the side. Although the straightening fins 13c are arranged vertically in FIG. 1, they may be arranged horizontally (not shown).

In the heat detector of this embodiment having the above-mentioned configuration, when the light-emitting element 17 is turned on while the detector is installed on the ceiling surface of a building, the entire tapered portion 15b of the element support member 15 emits light, and the light is visible from any direction between the multiple rectifying fins 13c, i.e., 360°, so there is no directionality in visibility. Therefore, there is no need to worry about the angle when installing on the ceiling surface, and the installation work can be completed in a short time. Moreover, the light-emitting area is larger than that of a detector equipped with a conventional point-emitting indicator light, and the light emitted from the tapered portion 15b also hits and is reflected by the surface of the rectifying fins 13c, making the apparent light-emitting surface larger, improving visibility.

In addition, in the heat detector 10 of this embodiment, the element support member 15 also serves as an operation indicator light, so the detector as a whole can be made smaller than the detector described in Patent Document 3, in which a ring-shaped operation indicator light is formed from a separate member from the member (element support) that forms the storage space for the thermistor 11 and is attached to the main body cover. Also, the number of parts can be reduced compared to the detector described in Patent Document 4, in which the element support, the protector acting as the indicator light, and the main body cover are constructed from separate members, thereby achieving cost reduction.

Furthermore, the heat detector 10 of this embodiment is configured to have a cone-shaped element support member 15 with a relatively large opening through which the thermistor 11 is inserted, improving assembly workability, and since the gap between the inner wall of the cylindrical portion 15a of the element support member 15 and the base of the thermistor 11 is filled with resin, the thermistor 11 can be supported in a stable state, and dust and moisture are less likely to enter the storage space of the circuit board, preventing dust and moisture from adversely affecting the circuit board.

Second Example
FIG. 3 is an explanatory front sectional view of the heat detector of the second embodiment, and FIG. 4 shows a specific example of an element support member 15 constituting the heat detector of the second embodiment.
Similar to the heat detector of the first embodiment, the heat detector 10 of the second embodiment includes a thermistor 11 as a heat-sensitive element, a body case 12 that houses a circuit board 14, a body cover 13 having a protector portion 13A that covers the tip of the thermistor 11, and an inverted cone-shaped element support member 15 that is joined to the surface of the circuit board 14. The difference from the heat detector of the first embodiment is that the shape of the element support member 15 is different, and that the shape of the body cover 13 has been changed in accordance with the change in the shape of the element support member 15. The second embodiment will be described below with an emphasis on these differences.

As shown in Figure 4 (A), the element support member 15 in the heat detector 10 of this embodiment has a cylindrical portion 15a, a tapered portion 15b, a flange portion 15c, a locking piece 15d and a light-guiding portion 15e, and differs from the element support member 15 of the first embodiment in that it is provided with a rib-shaped light-emitting portion 15g that protrudes downward along the outer periphery of the flange portion 15c.
In addition, due to the provision of light exit portion 15g, light reflecting portion 15f formed on the surface portion of flange portion 15c corresponding to light guiding portion 15e is formed so as to form a V shape when cross-sectioned in the vertical direction so as to reflect light from light guiding portion 15e to the outside, i.e., light exit portion 15g, which differs from element support member 15 of the first embodiment.
The light exit portion 15g has a ring shape when viewed from below as shown in Fig. 4(B). The light reflecting portion 15f is formed as a groove having a V-shaped cross section when viewed from the direction of the arrow C in Fig. 4(B) as in the first embodiment.

Furthermore, in association with the provision of a rib-like light-emitting portion 15g that protrudes downward along the outer periphery of the flange portion 15c, a slit 13e is formed in the body cover 13 as shown in Fig. 3, and the light-emitting portion 15g is fitted into this slit 13e so that its head faces the surface of the body cover 13. The slit 13e has a ring shape in a plan view corresponding to the light-emitting portion 15g.
As shown in Fig. 4A, the head of the light output section 15g is formed to have a shape that bulges downward, so that light is emitted from the light output section 15g while spreading due to a lens effect. The back surface of the light output section 15g may be microfabricated with a large number of thin linear grooves, similar to the back surface of the tapered section 15b. Also, fine particles that diffusely reflect light may be mixed into the material forming the element support member 15.

In this way, in the second embodiment, the ring-shaped slit 13e is formed in the body cover 13, so that the body cover 13 is divided into an outer plate and an inner plate, but the flow straightening fin 13c of the protector part 13A is made larger than in the first embodiment, and the base of the flow straightening fin 13c is formed to straddle the outer plate and the inner plate. As a result, the outer plate and the inner plate of the body cover 13 are connected to each other by the flow straightening fin 13c, and cannot be separated.

In the heat detector of the second embodiment configured as described above, when the light emitting element 17 is turned on while the heat detector is installed on the ceiling surface of a building, the entire tapered portion 15b of the element support member 15 and the ring-shaped light emitting portion 15g emit light, and the light is visible from between the multiple straightening fins 13c, i.e., from any direction of 360°, so there is no directionality in visibility and the total light emitting area is larger than that of the heat detector of the first embodiment. Also, the light emitted from the light emitting portion 15g illuminates the side surface of the straightening fins 13c, further improving visibility.
Furthermore, although the size of the straightening fins 13c is slightly larger than that of the heat detector of the first embodiment, the size of the main body cover 13 can be made approximately the same as that of the main body cover of the heat detector of the first embodiment, making it possible to reduce the size compared to conventional detectors and to reduce the number of parts as in the first embodiment.

(Variation 1)
Figures 5(A) and (B) show modified examples of the heat detector of the second embodiment. Of these, Figure 5(A) is an explanatory cross-sectional view of the element support member 15, and Figure 5(B) is a view showing the central portion (protector portion) of the main body cover 13 as viewed from below. Incidentally, Figure 5(A) shows a cross section taken along line A-A in Figure 5(B).

In this modified heat detector, as shown in FIG. 5(A), the flange 15c of the element support member 15 is formed to protrude outward, and trapezoidal convex portions 15h, which are nearly rectangular, are formed on the surface (the lower surface in the figure) of the flange 15c at a predetermined pitch in the circumferential direction. Also, as shown in FIG. 5(B), a plurality of windows 13f that can be fitted into the convex portions 15h are formed in the main body cover 13 in the circumferential direction. The back surface of the convex portions 15h may be microfabricated to form a number of thin linear grooves. The shape of the convex portions 15h is not limited to a trapezoid (quasi-rectangle), and any shape such as a rhombus, circle, or ellipse may be adopted.
The heat detector of this modified example can achieve substantially the same effects as the heat detector of the second embodiment, and can also improve the design effect.

(Variation 2)
FIG. 6 shows another modification common to the above embodiments.
6, instead of providing a cylindrical light guide portion 15e on the flange portion 15c of the element support member 15, a light guide portion 15e' consisting of a recess is provided on the back surface of the flange portion 15c, and a bullet-shaped light emitting element 17 is provided on a portion of the circuit board 14 facing the light guide portion 15e'. The light emitting element 17 is mounted by soldering a lead terminal to the circuit board 14. In addition, a light reflecting portion 15f is provided on the surface of the flange portion 15c at a portion corresponding to the light guide portion 15e' (the lower surface in the figure).
In the modification of Fig. 6, the light reflecting portion 15f has a rectangular shape when cross-sectionally taken in the vertical direction, but it may be formed to have a triangular shape as in Fig. 2. Note that the light reflecting portion 15f is formed as a recess (groove) having a V-shaped cross-section when viewed from the direction of the arrow C, as in the previous embodiment and modification.

Although the present invention has been described above based on the embodiment, the present invention is not limited to the above embodiment. For example, in the above embodiment, only one light guide portion 15e or 15e' is provided on the flange portion 15c of the element support member 15, but the light guide portions 15e or 15e' may be provided at multiple locations, and multiple light emitting elements 17 may be provided corresponding to these. Also, in the above embodiment, the taper portion 15b of the element support member 15 is provided with a locking piece 15d for mounting the element support member 15 to the circuit board 14, but the locking piece 15d may be provided on the flange portion 15c.
Furthermore, in the heat detector 10 of the above embodiment, resin is filled only inside the cylindrical portion 15a of the element support member 15, but it is also possible to configure the entire back and front sides of the circuit board 14 to be covered with resin to enhance waterproofing.

10 Heat detector 11 Thermistor (heat-sensitive element)
12 Body case 13 Body cover 13A Protector portion 13b Step portion 13c Flow straightening fin 13d Head cover 13e Slit 14 Circuit board 15 Element support member 15a Cylindrical portion 15b Tapered portion 15c Flange portion 15d Locking piece 15e, 15e' Light guiding portion 15f Light reflecting portion 15g Light output portion 15h Convex portion 16 Insulating resin (filler)
17 Light emitting element

Claims (5)

A heat detector in which a circuit board on which a heat-sensitive element and components constituting a detection circuit are mounted is housed inside a housing consisting of a main body case and a main body cover that covers the open side of the main body case,
an element support member made of a light-transmitting material, the element support member having an insertion cylindrical portion with an inner diameter larger than a diameter of the heat-sensitive element and a cone-shaped tapered portion that spreads outwardly downward from a lower end of the insertion cylindrical portion, the insertion cylindrical portion being attached to the circuit board such that the insertion cylindrical portion is positioned around the heat-sensitive element;
A heat detector characterized in that the entire tapered portion of the element support member is illuminated by light from a light-emitting element mounted on the circuit board. The body cover has an opening formed at a position corresponding to the heat-sensitive element, and includes a plurality of straightening fins that form an inlet through which outside air can flow in.
2. The heat detector according to claim 1, further comprising a head member which defines a space into which the tip of said heat sensitive element faces and covers said opening. The heat detector according to claim 1, characterized in that the element support member has a flange portion extending horizontally outward from the lower end of the tapered portion, and the flange portion is provided with a light introduction portion capable of introducing light from a light-emitting element mounted on the circuit board, and a light reflection portion that reflects the light introduced from the light introduction portion toward the tapered portion. the element support member includes a flange portion extending horizontally outward from a lower end of the tapered portion,
a light output portion protruding downward along a circumferential direction is formed on a peripheral edge portion of the flange portion of the element support member,
2. The heat detector according to claim 1, wherein the body cover is formed with a slit into which the light exit portion fits and which is exposed on a surface of the body cover. the element support member includes a flange portion extending horizontally outward from a lower end of the tapered portion,
A heat detector as described in claim 1, characterized in that the flange portion of the element support member has a plurality of convex portions formed in a row along the circumferential direction, and the main body cover has a plurality of windows formed therein that engage with the convex portions and are exposed on the surface of the main body cover.

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