JP2001325674A - Fire sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve waterproofing and acid-resistance/alkali-resistance by protecting charged urethane resins without requiring any complicated structure such as packing. SOLUTION: A circuit storage part 2 arranged with a circuit board 4, to which a lead wire 7 to be pulled out is connected, is filled with urethane resins as a filling agent 8 and further, all the upper surface of urethane resins is coated with waterproof and acid-proof/alkali-proof resins as a coating agent 10. As a coating agent 10, epoxy resins improved in waterproofing and acid- resistance/alkali-resistance are used, for example.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fire detector for detecting a fire using a thermistor or the like, and more particularly to a waterproof, acid and alkali resistant fire detector.

[0002]

2. Description of the Related Art Conventionally, fire detectors installed in high-temperature, high-humidity locations or locations where acidic or alkaline corrosive gases are generated, such as chemical factories, plating factories, hot springs, etc. It has a sealed structure that is not easily affected by gas.

[0003] Such a fire detector is disclosed, for example, in Japanese Utility Model Application Laid-open No.
-86994. In this fire detector, as shown in FIG. 5, a printed circuit board formed on the body 102 and connected with a lead wire 106 led out to the outside, as shown in FIG. 5, in order to have a sealed structure that is hardly affected by high temperature, high humidity and corrosive gas. A filling material 108 is filled in the storage recess 105 in which the storage 107 is disposed.
24, the lead wire outlet 1 through the presser fitting 122.
A silicone packing 119 provided with 20 is fixed.

[0004]

However, in such a conventional fire detector, a lead wire outlet 120 is provided on the upper surface of the storage recess 105 via a holding member 122 by a tapping screw 124. Since the packing 119 made of silicon is fixed, the number of parts is large and the assembly is complicated.

A urethane resin is used as the filler 108. If the urethane resin is placed in an acidic or alkaline corrosive gas for a long time, the urethane resin may be damaged. When water invades at high temperature, it is hydrolyzed and dissolved by chemical reaction,
There is a problem that the configuration in which the packing 119 is fixed to the upper surface of the storage recess 105 cannot be eliminated.

An object of the present invention is to provide a fire detector which protects a filled urethane resin without requiring a complicated structure such as a packing to improve waterproofness, acid resistance and alkali resistance.

[0007]

In order to achieve the above object, the present invention is configured as follows.

In the fire detector according to the present invention, a urethane resin is filled as a filling material in a circuit housing portion in which a circuit board to which a lead wire drawn to the outside is connected is provided. It is characterized by being coated with an acid and alkali resistant resin. As the waterproof, acid- and alkali-resistant resin to be coated, for example, an epoxy resin or a fluorine resin is desirable.

Further, according to the present invention, a urethane resin is filled as a filling material in a circuit housing portion in which a circuit board to which a lead wire led out is connected is provided, and the entire upper surface of the urethane resin is waterproofed or acid- and acid-resistant. It is characterized by attaching an alkaline nameplate seal. As a material of the nameplate seal, for example, polyethylene can be applied.

Further, according to the present invention, a urethane resin is filled as a filling material in a circuit housing portion in which a circuit board to which a lead wire led out is connected is disposed, and the entire upper surface of the urethane resin is waterproofed or resistant to acid and acid. It is characterized by forming an alkaline coating film. The paint used for forming the coating film is, for example, a paint using a fluorine-based resin. Further, a multi-layer coating film may be formed by repeatedly applying a paint having acid resistance, alkali resistance, and waterproofness.

[0011]

FIG. 1 is a sectional view showing a first embodiment of the present invention. In FIG. 1, a sensor main body 1 has a circuit housing portion 2 formed therein and an outer cover 3 formed below. A printed circuit board 4 is disposed in the circuit housing portion 2, and a thermistor 5 is connected to the printed circuit board 4 in a downward direction. The tip is located at the position to receive the flow.

The penetrating portion of the sensor body 1 of the thermistor 5 is sealed by bonding with an adhesive 6. The thermistor 5 is made of a silicon-based resin for durability and is coated with an epoxy-based resin.

As the adhesive 6, a silicone resin or an epoxy resin is used. Instead of using the adhesive 6 for mounting the thermistor 5, the thermistor 5 may be integrally molded when the sensor body is molded with resin.

A lead wire 7 is drawn out of the printed circuit board 4 disposed in the circuit housing portion 2 to the outside on the ceiling surface side. The printed circuit board 4 is provided with a sensor circuit for transmitting a fire detection signal from a lead wire when the temperature detected by the thermistor 5 exceeds a predetermined temperature for judging a fire.
The electrical components for this purpose may be mounted on either surface of the printed circuit board 4, but it is desirable to mount the electric components on the lower surface side of the printed circuit board 4 in order to increase waterproofness, acid resistance, and alkali resistance.

A urethane resin is filled as a filler 8 in the circuit housing portion 2 in which the printed circuit board 4 to which the lead wire 7 and the thermistor 5 led out are connected. Further, the entire upper surface of the urethane resin is coated with a waterproof, acid- and alkali-resistant resin with a coating agent 10. As the coating agent 10, an epoxy resin, a fluorine resin, or the like having high durability even when placed in a high temperature, high humidity, or an acidic or alkaline corrosive gas is used.

Next, the operation will be described. In the embodiment of FIG. 1, the lead wire 7 and the thermistor 5
A urethane resin is filled as the filler 8 in a state where the printed circuit board 4 connected to the circuit board 2 is disposed in the circuit accommodating section 2, and the entire upper surface of the urethane resin is waterproofed with epoxy resin or the like.
Coating agent 10 made of acid- and alkali-resistant resin
Coating, the corrosive gas does not directly contact the urethane resin filler 8 even when placed in an acidic or alkaline corrosive gas for a long period of time, and the urethane resin is attacked by the corrosive gas. Thus, the occurrence of troubles due to corrosion of the electric components and the connection portions of the printed circuit board 4 is reliably prevented, and stable operation for a long period of time is guaranteed. In addition, high temperature
Even in a highly humid place, the moisture does not come into contact with the filler 8 by the coating agent 10, and the moisture does not cause a chemical reaction of the urethane resin to be dissolved by hydrolysis.

Further, since it is only necessary to coat the filler 8 with the waterproof, acid- and alkali-resistant coating agent 10, the conventional mounting structure of the packing is not required.
The number of parts is reduced, and the number of assembly steps can be reduced.

In the above-described embodiment, the coating agent 10 is a resin having waterproof, acid- and alkali-resistant properties. However, in the case of a simple waterproof fire detector, the coating agent 10 is made of an acid-resistant resin. -Even if the alkali resistance is slightly poor, a coating agent having good waterproof properties can be applied. For example, a silicon-based resin can be used.

FIG. 2 shows a second embodiment of the present invention. In this embodiment, a circuit housing 2 in which a printed board 4 to which a lead wire 7 and a thermistor 5 connected to the outside are connected is provided. A urethane resin is filled as the filler 8, and a waterproof, acid- and alkali-resistant nameplate seal 11 is attached or adhered to the entire upper surface of the urethane resin. As the material of the nameplate seal 11, polyethylene or the like having high waterproofness, acid resistance and alkali resistance is used.

Also in the second embodiment, the nameplate seal 11 is adhered or adhered to the entire upper surface of the filler 8 made of urethane resin, so that the acidic or alkaline corrosive gas or moisture is reduced by the urethane resin filler. The number of parts can be reduced by preventing contact with the mounting member 8 and by eliminating the need for a packing mounting structure, thereby reducing the number of assembly steps.

FIG. 3 shows a third embodiment of the present invention. In this embodiment, the circuit housing 2 is provided with a printed circuit board 4 to which a lead wire 7 and a thermistor 5 connected to the outside are connected. A urethane resin is filled as the filler 8, and a waterproof, acid- and alkali-resistant paint is sprayed or applied over the entire upper surface of the urethane resin to form a coating film 12.
Is formed. As a paint for forming the paint film 12, for example, a paint using a fluorine-based resin is used.

FIG. 4A is an enlarged view of a portion A in FIG.
On the upper surface of the filler 8 made of urethane resin, a one-layer coating film 12 is formed with a waterproof, acid- and alkali-resistant paint. If the waterproofness, acid resistance and alkali resistance cannot be sufficiently obtained with one paint, as shown in FIG. 4B, a two-layer coating is performed by applying an acid-resistant paint and an alkali-resistant paint on each other. The films 12a and 12b may be formed. Of course, a multilayer coating film 12 may be formed as necessary in consideration of acid resistance, alkali resistance, and waterproofness.

Also in the third embodiment, since the coating film 12 is formed on the entire upper surface of the filler 8 made of urethane resin, an acidic or alkaline corrosive gas or moisture is added to the filler 8 made of urethane resin. Contact is prevented and the number of parts is reduced by eliminating the need for a packing mounting structure, thereby reducing the number of assembly steps.

Note that the present invention is not limited to the above-described embodiment, and includes appropriate modifications without impairing the objects and advantages thereof.

[0025]

As described above, according to the present invention, a waterproof or acid- and alkali-resistant coating, a nameplate seal is attached, or a paint film is formed on the entire upper surface of the urethane resin filled in the circuit housing. This allows the urethane resin that protects the printed circuit board to be attacked by corrosive gas or hydrolyzed by water, even if it is installed in high-temperature, high-humidity locations or locations that receive acidic or alkaline corrosive gases. Melting can be reliably prevented, and stable operation can be guaranteed for a long period of time.

Further, since it is not necessary to provide a packing or the like on the upper surface side of the circuit housing portion, the number of parts can be reduced and the number of assembling steps can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment of the present invention.

FIG. 2 is a sectional view of a second embodiment of the present invention.

FIG. 3 is a sectional view of a third embodiment of the present invention.

FIG. 4 is an explanatory view of the coating film of FIG. 3;

FIG. 5 is an explanatory view of a conventional fire detector.

[Explanation of symbols]

 1: Sensor body 2: Circuit housing 3: Outer cover 4: Printed circuit board 5: Thermistor 6: Adhesive 7: Lead wire 8: Filler (urethane resin) 10: Coating agent 11: Nameplate seal 12: Paint film

Claims (3)

[Claims] An urethane resin is filled as a filler in a circuit housing portion in which a circuit board to which a lead wire led out is connected is filled with a urethane resin as a filler, and a waterproof or acid- and alkali-resistant resin is provided on the entire upper surface of the urethane resin. A fire detector characterized by coating. 2. A urethane resin is filled as a filling material in a circuit housing portion in which a circuit board to which a lead wire drawn to the outside is connected is provided, and a waterproof or acid- and alkali-resistant nameplate is provided on the entire upper surface of the urethane resin. A fire detector with a sticker attached. 3. A urethane resin is filled as a filling material in a circuit housing portion on which a circuit board to which a lead wire drawn out is connected is disposed, and a waterproof or acid- and alkali-resistant coating is applied to the entire upper surface of the urethane resin. A fire detector characterized by forming a film.