JP2002352345A - Fire sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fire sensor capable of improving thermal response by improving heat transfer coefficient to a heat sensing element. SOLUTION: A protecting cover 4 is formed in a position deflecting from a center position of a bottom plate 4 so that a fin 18 for flow straightening corresponds to a drooping position of a thermistor 6, and six fins 18 for flow straightening are formed radially at equal intervals with an arranging position A of the thermistor 6 as the center. Two pieces of the fins 18 for flow straightening formed with the center position in between on a straight line X linking a peripheral vertical sash bar 5c and the arranging position A of the thermistor 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fire detector provided with a heat sensing element.

[0002]

2. Description of the Related Art Fire detectors for detecting the temperature of smoke using a heat sensing element have been conventionally provided. This type of fire detector has an outer shell cover in which a heat sensing element, for example, a thermistor, is provided, and the outer shell cover serves as a protective cover for the thermistor.

[0003]

By the way, there has been provided a composite type fire detector having a smoke detecting function in addition to the heat detecting function by the above-mentioned heat detecting element. In some cases, the heat sensing element cannot be arranged at the center position in the outer cover due to the relationship with the optical system.

[0004] For this reason, the reinforcing vertical rail provided on the peripheral wall for supporting the outer shell cover closest to the heat sensing element becomes an obstacle, and the response of the heat sensing element to heat detection sometimes deteriorates.

FIG. 9 shows a flow velocity vector diagram of the conventional structure. As can be seen from this figure, when the air Y containing heat flows from the left direction, the flow velocity around the heat sensing element 6 is slow because the flow is from a direction in which the heat sensing element 6 is hidden by the vertical rail 5c. Therefore, there has been a problem that thermal responsiveness becomes dull.

The present invention has been made in view of the above problems, and an object of the present invention is to increase the heat transfer coefficient to the heat sensing element and improve the thermal responsiveness. It is to provide a fire detector.

Another object of the present invention is to provide a fire detector capable of reducing a decrease in flow velocity due to a structure including a vertical rail and a rectifying fin itself.

A third object of the present invention is to provide a fire detector capable of minimizing the above-mentioned decrease in flow velocity in addition to the object of the second embodiment.

A fourth object of the present invention is to provide a fire detector capable of optimally setting the flow velocity reduction and the thermal conductivity even when the outer cover is eccentric, in addition to the above objects. It is in.

[0010]

In order to achieve the above object, according to the first aspect of the present invention, a suspended heat sensing element and a heat sensing element are disposed so as to surround the heat sensing element, and the heat sensing element is disposed inside and outside the peripheral wall. A bottomed cylindrical outer shell cover formed with a communicating smoke inlet, wherein the heat sensing element is located at the center and both ends are positioned on a straight line passing through the center in a radial direction. A plurality of rectifying fins are provided in the outer shell cover.

According to a second aspect of the present invention, in the first aspect of the present invention, the outer peripheral wall of the outer shell cover is provided with a reinforcing vertical bar vertically suspended at a predetermined interval in a circumferential direction from a peripheral edge of a bottom portion. The smoke inlet is opened between the bars, and at least one of the rectifying fins is located on a straight line connecting the vertical bar and the heat sensing element.

According to a third aspect of the present invention, in the second aspect of the present invention, the rectifying fan located on a straight line connecting the vertical rail and the heat sensing element is a rectifying fan located closest to the vertical rail. It is characterized by including.

According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, the length dimension of each of the rectifying fins in both end directions, and one end of the rectifying fin adjacent to the heat sensing element and The ratio to the distance to the heat sensing element is set to be larger than 0 and smaller than 3.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment.

The fire detector according to the present embodiment is a composite type having a heat detection function as a heat detector and a smoke detection function as a smoke detector. As shown in FIGS. And a light-emitting diode L
A circuit board 2 on which an ED, a photodiode PD, and circuit components of a smoke detection circuit described later are mounted, and a horizontal labyrinth wall 9 surrounded by a labyrinth wall 9 for permitting intrusion of smoke from the outside and preventing incidence of external light. The circuit board includes a smoke sensing chamber S having a substantially circular cross section, and optical components are mounted in the smoke sensing chamber S, and the light emitting diode LED and the photodiode PD face the optical components. An optical base 3 on which the optical base 2 is mounted, an insect-proof cover 4 for preventing insects and the like from entering the smoke sensing chamber S provided on the optical base 3, and an outer shell cover 5 as a protective cover. .

The body 1 has a substantially disk-shaped main part 1a and a main part 1a.
and a side wall 1b protruding upward from the outer peripheral edge of the main portion 1a.
The upper end of the outer shell cover 5 holding the optical base 3 to which the circuit board 2 is fixed and the insect-proof cover 4 is inserted and fixed in the round hole 1c.

A light emitting diode LE is provided on the lower surface of the circuit board 2.
D is implemented. Although not shown, a photodiode PD formed as a chip is mounted on the lower surface of the circuit board 2. Further, a thermistor 6 as a heat sensing element is mounted on the lower surface of the circuit board 2 in a state where the heat sensing portion is protruded downward. This mounting position is set so as to be shifted from the center of the sensor.

As described above, the fire detector according to the present embodiment includes the thermistor 6 as a heat-sensitive element, and has a heat detection function in addition to a smoke detection function.

The optical base 3 is made of black synthetic resin and is disposed along a substantially disk-shaped bottom plate 7, a rectangular frame-shaped side wall 8 protruding from the upper surface of the bottom plate 7, and an outer peripheral portion on the lower surface of the bottom plate 7. And a labyrinth wall 9 composed of a plurality of partition walls 9a having a substantially rectangular cross-section.

A plurality of partition walls 9a constituting the labyrinth wall 9
Are arranged at predetermined intervals so that the bent portion of the intermediate portion enters between the two end portions of the adjacent partition 9a, and one end of the smoke introduction path formed between the adjacent partition 9a is connected to the outside. The other end communicates with the smoke detection chamber S. Here, each partition 9a is formed in black so that reflection does not occur, and since the middle part of the smoke introduction path is bent, external light is prevented from directly entering the smoke sensing chamber S. Has become.

In the recess 10 surrounded by the bottom plate 7 and the side wall 8 of the optical base 3, the surface on which the light emitting diode LED, the photodiode PD and the thermistor 6 are mounted is provided with the bottom plate 7.
The circuit board 2 is mounted on the side. Bottom plate 7 of optical base 3
In a portion corresponding to the light emitting diode LED and the photodiode PD, respectively, a protruding base 19 protruding downward,
The protrusions 19 and 20 are formed with through holes 11a and 11b penetrating the bottom plate 7.

Each protruding portion 19, 20 has a through hole 11a,
Grooves 19a and 20a are formed to extend toward the center of the optical base 3 respectively, and the prism lenses 12 and 13 are mounted in these grooves 19a and 20a. Here, the prism lenses 12 and 13 are attached to the optical base 3 with one surface facing the through holes 11a and 11b and the other surface facing the center direction of the optical base 3, The upper side and both left and right sides of 13 are covered by the protruding portions 19 and 20. Further, the prism lenses 12 and 13 are arranged so that the optical axes face the center direction of the smoke sensing chamber S and intersect at a predetermined angle.

As described above, the prism lenses 12 and 13 are the light emitting surface of the light emitting diode LED and the photodiode PD
Light-emitting diodes LE
The light emission of D is condensed by the prism lens 12 and is irradiated to the smoke sensing chamber S. When smoke enters the smoke detection room S,
The light emitted from the prism lens 12 is scattered by smoke particles and enters the prism lens 13. And
The light incident on the prism lens 13 is
Since light is condensed on the light receiving surface of the photodiode PD by 3, the intrusion of smoke can be detected from an increase in the output of the photodiode PD.

Incidentally, a shield cover, which is formed in a box shape which is conductive and has an open surface, is used at the portion of the optical base 3 facing the photodiode PD and is used to reduce environmental disturbance noise to the ground level. 14 is insert-molded, and when the circuit board 2 is placed in the recess 10, the shield cover 14 covers around the photodiode PD mounted on the circuit board 2, and the photodiode PD
Is to be shielded. The shield cover 14 is provided with an earth pin 14 a protruding toward the circuit board 2. The earth pin 14 a is inserted into a through-hole provided in the circuit board 2, and is connected to a ground line (not shown) of the circuit board 2. Soldered. The shield cover 14 has a communicating hole 14b communicating with the through hole 11b.
Is formed, and the light condensed by the prism lens 13 through the communication hole 14b is applied to the light receiving surface of the photodiode PD.

The optical base 3 has four terminal pins 15
Are formed by insert molding, and each terminal pin 15 is inserted into a through hole (not shown) provided in the circuit board 2 and soldered, so that each terminal pin 15 is electrically connected to a wiring pattern of the circuit board 2. And the distal end of each terminal pin 15 protruding from the circuit board 2 to the opposite side serves as an external connection terminal. Further, the circuit board 2 is held on the optical base 3 by soldering the terminal pins 15 insert-molded on the optical base 3 to the circuit board 2.

The insect repellent cover 4 is formed of a synthetic resin having an insulating property and has a bottomed cylindrical shape.
Is formed with a through-hole 4d for inserting the thermistor 6 mounted on the circuit board 2 downward, and a mesh portion 4c in which a plurality of holes are opened in a lattice pattern is formed in the peripheral wall 4b. The insect repellent cover 4 is attached to the optical base 3 with the lower end of the optical base 3 inserted into the cylinder, and the surrounding wall 4b around the labyrinth wall 9 on which the mesh portion 4c is formed.
, It is possible to prevent insects and dust of the same size from entering the smoke sensing room S surrounded by the labyrinth wall 9. The bottom plate 4a of the insect cover 4 is provided with the bottom plate 7 of the optical base 3.
Lid portions 21 and 22 projecting upward (toward the optical base 3 side) at portions opposing the protruding base portions 19 and 20 provided on the protruding base portions 19 and 20 and fitting with the grooves 19 a and 20 a provided on the protruding base portions 19 and 20. It is formed integrally.

When the insect cover 4 is put on the optical base 3, the lids 21 and 22 provided on the insect cover 4 are fitted into the grooves 19a and 20a provided on the optical base 3, respectively, and the prism lens is formed. The projection surface 19, 20 and the lid portions 21, 22 surround the outgoing surface 12 and the incident surface of the prism lens 13 around the outgoing surface 12 and the prism lens 13, thereby providing an optical seal.

The outer cover 5, which is a protective cover, is made of a synthetic resin having elasticity and has a bottomed cylindrical shape.
An engaging claw 16 protruding outward is protruded from the upper end of a.
A substantially lower half of the peripheral wall 5a is provided with reinforcing vertical bars 5c whose lower ends are integrally connected to the bottom portion 5b at predetermined intervals in the circumferential direction, and an annular horizontal bar held integrally with the vertical bars 5c. 5d are provided at predetermined intervals in the vertical direction to open a plurality of strip-shaped smoke inlets 17 extending in the circumferential direction, project upward from the bottom 5b, and contact the tip with the bottom plate 4a of the insect repellent cover 4. A plurality of rectifying fins 18 protrude. The plurality of rectifying fins 18 are radially arranged around the thermistor 6, and rectify the air flow so that the air flowing into the inside from the smoke inlet 17 around the periphery hits the heat-sensitive portion of the thermistor 6. ing. The bottom 5b surrounded by the rectifying fins 18 is provided with an opening 5e through which the tip of the thermistor 6 faces the outside.

When assembling the fire detector, first, the light emitting diode LED, the photodiode PD, the thermistor 6, and the circuit component of the smoke detection circuit are mounted on the circuit board 2, and the circuit board 2 is mounted on the optical base. 3, the ground pin 14 a and the terminal pin 15 of the shield cover 14 are soldered to the circuit board 2, and the circuit board 2 is fixed to the optical base 3. Next, the insect-proof cover 4 and the optical base 3 to which the circuit board 2 was attached were inserted into the cylinder of the outer-shell cover 5, and the insect-proof cover 4 and the optical base 3 were held by the outer cover 5. Thereafter, when the upper end of the outer shell cover 5 is inserted into the round hole 1c of the body 1, the engaging claw 16 protruding from the upper end of the outer shell cover 5 and the engagement formed on the inner peripheral surface of the round hole 1c. The stepped portion 1d is unevenly engaged, and the outer shell cover 5 is
It is combined with.

Here, the relationship between the thermistor 6 as a heat sensing element, which is a main component of the present invention, and the rectifying fins 18 of the protective cover 4 will be described in detail.

First, the protective cover 4 is constructed as shown in FIGS. 1A to 1C. As shown in FIG. 1A, the rectifying fins 18 are arranged so that the rectifying fins 18 correspond to the hanging position of the thermistor 6. And six rectifying fins 18 are formed radially at equal intervals around the arrangement position A of the thermistor 6. Then, on a straight line X connecting the surrounding vertical bar 5c and the arrangement position A of the thermistor 6, two pieces of rectifying fins 18 formed so as to sandwich the center position, as shown in FIG. The outer straightening fin 1 closest to the vertical bar 5c between the bar 5c and the thermistor 6
8 are arranged so as to be hidden.

The reason why the rectifying fins 18 are arranged on the straight line X connecting the vertical bar 5c of the protective cover 4 and the thermistor 6 is that at this position the flow rate of the vertical bar 5c is most greatly reduced.
This is because the position of the rectifying fin 18 is at a position where the obstruction of the air flow by the rectifying fin 18 itself is minimized.

These effects will be compared between the case where the rectifying fins 18 are provided and the case where there is no conventional fin, with reference to flow velocity vector diagrams shown in FIGS. In the case of FIG. 9, as described above, the airflow Y entering from the left direction hits the vertical rail 5c on the left side, and it is difficult for air to flow to the thermistor 6 behind it, whereas in the case of the present embodiment shown in FIG. The rectifying fins 18 provided radially about the thermistor 6
The air is collected to secure the flow velocity around the thermistor 6.

FIG. 6 shows a simulated temperature of the thermistor 6 two seconds after the stair climb test in this structure, and FIG. 6 shows a simulated flow velocity around the thermistor 6.
(A) and (b) show. In the figure, 0 on the vertical axis indicates the center position of the thermistor 6, and the larger the value, the farther from the center position of the thermistor 6. The simulation conditions were as follows: the inflow speed was 0.8 m / sec, the inflow temperature was increased from 25 ° C. at 3 ° C./min, and the inflow position was 0.4 m away from the fire detector installation position ( FIG. 6 (a) showing the analysis result under the condition that the position of the heater is for air heating).
Shows the value two seconds after the start of the inflow, and the flow velocity distribution in FIG. 6B shows the steady state.

6 (a) and 6 (b), the temperature rise of the thermistor 6 is faster and the thermistor 6 has a higher temperature than the case (b) without the rectifying fins 18 of this embodiment. It can be seen that the flow rate near 6 is high, so that the temperature transfer rate is improved and the responsiveness is also improved.

On the other hand, the temperature transfer coefficient varies depending on the distance between the thermistor 6 and one end of the rectifying fin 18 or the length dimension between both ends of the rectifying fin 18. Various positional relationships will be described.

First, as shown in FIG. 7, the distance a between the thermistor 6 and one end of the rectifying fin 18 and the rectifying fin 1
Assuming that the length between both ends of 8 is b, the thermistor 6 is deviated from the center of the bottom 5b, so that a + b = 9m
Considering the case of m, the ratio b / a of the length b of the rectifying fin 18 and the distance a between the thermistor 6 and the rectifying fin 18 is defined as the interval ratio. Under these conditions, a simulation based on the same stair climb test as described above shows that the length b between the two ends of the rectifying fin 18 is based on the case where the interval ratio is 0, that is, the length of the rectifying fin 18 is 0. If the length is made longer, the concentration ratio of air to the thermistor 6 by the rectifying fins 18 increases, the heat transfer to the thermistor 6 becomes better, and the temperature of the thermistor 6 rises.

However, if the rectifying fins 18 become longer, that is, if the rectifying fins 18 are too close to the thermistor 6, the distance between the rectifying fins 18 and the thermistor 6 becomes narrower, and the air resistance gradually increases. Street gets worse. Therefore, it becomes difficult for air to pass through the thermistor 6, and conversely, the temperature rise of the thermistor 6 decreases. Table 1
8 summarizes the relationship between the dimension a, the dimension b, and the ratio (b / a) of both, and FIG. 8 shows the ratio between the length b of the both ends of the rectifying fin 18 and the distance a of the interval, the temperature, 6 is a graph showing a relationship with the graph.

[0039]

[Table 1] From the above results, it is necessary to set the spacing ratio b / a to less than 3 in order to improve at least the state without the rectifying fins 18 at all. That is, when the distance ratio is set to be larger than 0 and smaller than 3 under the condition that a + b is 9 mm, the distance a between the rectifying fin 18 and the thermistor 6 needs to exceed 2.25 mm.

As described above, the vertical bar 5c of the outer shell cover 5,
At least one rectifying fin 18 is provided on a straight line connecting the thermistor 6 and a ratio b between a length dimension b between both ends of the rectifying fin 18 and a distance a between the rectifying fin 18 and the thermistor 6 is b. By setting / a to less than 3, the outer shell cover 5
The heat transfer efficiency when the thermistor 6 is disposed inside is improved, and the thermistor 6 can efficiently detect the heat of smoke even when the position of the thermistor 4 is deviated from the center of the outer shell cover 5. In other words, by satisfying the above conditions, the degree of freedom in the arrangement of the rectifying fins 16 increases, and the fire detector can be reduced in size.

[0041]

According to the first aspect of the present invention, there is provided a bottomed cylindrical member having a suspended heat sensing element and a smoke inlet formed to surround the heat sensing element and communicate with the inside and outside of the peripheral wall. And a plurality of rectifying fins radially arranged around the position of the heat sensing element and at both ends on a straight line passing through the center. Since it is provided inside, there is an effect that the heat transfer coefficient to the heat sensing element can be increased and the thermal responsiveness can be improved.

According to a second aspect of the present invention, in the first aspect of the invention, the outer peripheral wall of the outer shell cover is provided with a reinforcing vertical bar which is vertically erected at a predetermined interval from a peripheral edge of a bottom portion. Since the smoke inlet is opened between the crosspieces and at least one of the rectification fins is located on a straight line connecting the vertical crosspiece and the heat sensing element, the vertical crosspiece and the rectification fin itself are arranged. There is an effect that a decrease in flow velocity due to the configuration including the above can be reduced.

According to a third aspect of the present invention, the rectifying fan located on a straight line connecting the vertical rail and the heat sensing element is the rectifying fan located closest to the vertical rail, so that the flow velocity is reduced. Can be minimized.

According to a third aspect of the present invention, in the fourth aspect of the present invention, in any one of the first to third aspects, the length of the rectifying fin in both end directions and the length of the rectifying fin adjacent to the heat-sensing element are determined. Since the ratio of the distance between one end of the rectifying fin and the heat sensing element is greater than 0 and less than 3, even if the position of the heat sensing element is deviated with respect to the center of the outer shell cover, the flow velocity decreases. Of course, the heat transfer coefficient can be optimized, and by satisfying the above conditions, the degree of freedom in the arrangement of the heat sensing element is increased, and the size of the fire detector is reduced. This has the effect of making it possible.

[Brief description of the drawings]

FIG. 1A is a horizontal cross-sectional view of an outer shell cover used in an embodiment of the present invention at a cross rail portion. (B) is a front view of the outer shell cover used in the above. (C) is a horizontal sectional view of a peripheral wall portion of the outer shell cover used in the above.

FIG. 2 is a front sectional view of the whole of the same.

FIG. 3 is a front sectional view of the same disassembled state.

FIG. 4 is an exploded perspective view of the same.

FIG. 5 is a flow velocity vector diagram for the outer shell cover of the present embodiment.

FIG. 6A is a diagram simulating the temperature of a thermistor two seconds after a stair climb test in the structure of the outer cover shown in FIGS. 4 and 5; FIG. 6B is a diagram simulating the flow velocity around the thermistor at the time of the stair climbing test in the structure of the outer shell cover shown in FIGS. 4 and 5.

FIG. 7 is an explanatory diagram of a dimensional relationship between a rectifying fin of the outer shell cover and a thermistor according to the embodiment.

FIG. 8 is a graph showing the relationship between the ratio of the length b and the interval a of both ends of the rectifying fin of the outer shell cover and the temperature.

FIG. 9 is a flow velocity vector diagram for the outer shell cover when there is no vertical bar.

[Description of Signs] A Arrangement position X Straight line 5 Outer shell cover 5a Peripheral wall 5b Bottom plate 5c Vertical bar 5d Horizontal bar 5e Opening 17 Smoke inlet 18 Rectifying fin

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[Procedure amendment]

[Submission date] May 31, 2001 (2001.5.3)
1)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction contents]

According to a second aspect of the present invention, in the first aspect of the present invention, the outer peripheral wall of the outer shell cover is provided with a reinforcing vertical bar vertically suspended at a predetermined interval in a circumferential direction from a peripheral edge of a bottom portion. The smoke inlet is opened between the bars, and at least one of the rectifying fins is located on a straight line connecting the vertical bar and the heat sensing element.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

According to a third aspect of the present invention, in the second aspect of the present invention, the rectifying fin located on a straight line connecting the vertical bar and the heat sensing element is a rectifying fin located closest to the vertical bar. It is characterized by including.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0042

[Correction method] Change

[Correction contents]

According to a second aspect of the present invention, in the first aspect of the invention, the outer peripheral wall of the outer shell cover is provided with a reinforcing vertical bar which is vertically erected at a predetermined interval from a peripheral edge of a bottom portion. The smoke inlet is opened between the crosspieces, and the straightening fins are formed on a straight line connecting the vertical crosspiece and the heat sensing element.
Since at least one is located, there is an effect that a decrease in flow velocity due to the configuration including the vertical rail and the rectifying fin itself can be reduced.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0043

[Correction method] Change

[Correction contents]

According to a third aspect of the present invention, since the rectifying fin located on a straight line connecting the vertical rail and the heat sensing element is the rectifying fin located closest to the vertical rail, the flow velocity lowering is achieved. Can be minimized.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Koji Sakamoto, Inventor 1048 Kadoma, Kadoma, Osaka Pref. Matsushita Electric Works, Ltd. Terms (reference) 5C085 AA01 AA03 AB09 AC03 BA04 BA12 CA08 CA30 DA07 DA08 FA09 FA10 FA31

Claims (4)

[Claims] The present invention comprises a heat sensing element which is suspended, and a bottomed cylindrical outer shell cover which is disposed so as to surround the heat sensing element and which has a smoke inlet communicating with the inside and outside of the peripheral wall. In the fire detector, the positions of the heat sensing elements are shifted from the center position of the outer shell cover, and the heat sensing elements are radially arranged such that both ends are positioned on a straight line passing through the center with the center as the center. A fire detector comprising a plurality of rectifying fins provided in an outer shell cover. 2. A peripheral wall of the outer shell cover is provided with a reinforcing vertical bar vertically suspended at a predetermined interval from a peripheral edge of a bottom portion, and the smoke inlet is opened between the vertical bars. 2. The fire detector according to claim 1, wherein at least one of the rectifying fins is located on a straight line connecting the vertical rail and the heat sensing element. 3. The rectifying fan located on a straight line connecting the vertical rail and the heat sensing element is a rectifying fan closest to the vertical rail. Fire detector. 4. The ratio of the length of the rectifying fin in both end directions to the distance between one end of the rectifying fin adjacent to the heat-sensing element and the heat-sensing element is greater than zero.
The fire detector according to any one of claims 1 to 3, wherein the fire detector is set to be less than the above.