JP2012009079A - Method for manufacturing heat sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a heat sensor, which keeps production efficiency and also improves waterproof property in a lead-in portion of a lead wire without increasing an installation cost.SOLUTION: This invention relates to a method for manufacturing a heat sensor 1 in which a lead wire 10 is made to penetrate a waterproof lid 5 forming a waterproof area 7 of the heat sensor 1 via an elastomer 20, thereby leading-in the lead wire 10 to the inner part of the waterproof area 7. The olefin elastomer 20 is fixed by potting in the circumference of the lead wire 10 coated by polyethylene. Insert molding is performed so as to allow the lead wire 10 with the elastomer 20 fixed thereto to penetrate the waterproof lid 5, which is formed with an ABS resin, a PC resin, or a PBT resin, and to be led-in to the inner part of the waterproof area 7, and also so as to allow the elastomer 20 to interpose between the waterproof lid 5 and the lead wire 10. Thus, the elastomer 20 is thermally bonded to the waterproof lid 5 and the lead wire 10 respectively.

Description

  The present invention relates to a method for manufacturing a heat sensor, and more particularly to a method for manufacturing a heat sensor that can improve waterproofness in a lead-in portion.

Among fire alarms such as heat detectors, fire detectors, and repeaters, especially fire alarms such as those installed in kitchens, etc. are waterproofed to prevent water from entering the electrical parts. It is necessary to cover and protect the area. When such a waterproof region is formed, it is important to form a certain waterproof structure around the lead wire because water easily enters from around the lead wire drawn into the waterproof region.
Conventionally, in such a waterproof structure for fire alarm equipment, a waterproof lid that partitions the waterproof area and a lead wire that penetrates the waterproof lid are integrally formed by insert molding.

  However, the waterproof lid is made of ABS (acrylonitrile butadiene styrene) resin, PC (polycarbonate) resin, PBT (polybutylene terephthalate) resin, etc., whereas the lead wire coating layer is made of vinyl chloride. The thermal adhesiveness between these resins is poor. Therefore, there is a possibility that a slight gap may be generated between the waterproof lid and the lead wire, which may cause insulation failure in the waterproof test of the type test defined by the Fire Service Act.

As another waterproof structure, it is also conceivable that the lead wire is passed through the waterproof lid and then potted with an adhesive resin is provided around the lead wire. In this case, more reliable waterproof performance can be obtained as compared with the case of simple insert molding.
However, in this case, there is a problem that the curing time of the adhesive is relatively long and the production efficiency is lowered. In addition, an apparatus capable of shortening the curing time by heating the adhesive resin has been proposed. However, when such an apparatus is introduced, the equipment cost is significantly increased, which is not preferable. .

  The present invention has been made in view of the above problems, and a method of manufacturing a heat sensor that can maintain the production efficiency and can improve the waterproofness in the lead-in portion without increasing the equipment cost. The purpose is to provide.

  In order to achieve such an object, the manufacturing method of the heat sensor according to claim 1 is characterized in that the lead wire is penetrated through an elastomer through a waterproof portion forming a waterproof region of the heat sensor. Is a method for manufacturing a heat sensor, in which the olefin-based elastomer is fixed by potting around the lead wire covered with polyethylene, and the elastomer is fixed. With respect to the waterproof part formed of ABS resin, PC resin, or PBT resin, the lead wire penetrates the waterproof part and is drawn into the waterproof region; and Insert molding is performed so that the elastomer is interposed between the waterproof portion and the lead wire, so that the elastomer is formed between the waterproof portion and the lead wire. Thermally adhered to respectively.

It is a longitudinal cross-sectional view of the heat sensor to which this structure is applied in one embodiment of this invention. It is an enlarged view of the junction part of FIG. It is a perspective view of the junction part of FIG.

  Embodiments of a method for manufacturing a heat sensor according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In particular, the present embodiment shows an example in which the present structure is applied to a lead-in portion of a heat sensor lead, but the present structure can be similarly applied to any fire alarm equipment. .

  FIG. 1 is a longitudinal sectional view of a heat sensor 1 to which this structure is applied. As shown in FIG. 1, the heat sensor 1 includes a thermistor 3, a printed circuit board 4, and a waterproof lid 5 as a waterproof part inside a housing 2. Among these, the thermistor 3 is a thermal element that measures the temperature of air. Further, an electrical component such as an IC (not shown) is mounted on the printed circuit board 4 and performs various controls such as temperature measurement using the thermistor 3. The waterproof lid 5 is detachably attached to the housing 2 above the printed circuit board 4 in the drawing, and the housing 2 and the waterproof lid 5 allow the waterproof substrate 5 to accommodate the printed circuit board 4 and the like. 7 is formed.

Here, the heat sensor 1 is provided with a lead wire 10 for inputting / outputting various control signals to the heat sensor 1 or supplying power. The lead wire 10 is arranged so that the tip end portion penetrates the waterproof lid 5 and reaches the inside of the waterproof region 7.
Next, a joint portion between the lead wire 10 and the waterproof lid 5 will be described. 2 is an enlarged view of the joint portion of FIG. 1, and FIG. 3 is a perspective view of the joint portion of FIG.
As shown in FIGS. 2 and 3, an elastomer (thermoplastic resin) 20 is provided between the lead wire 10 and the waterproof lid 5. The elastomer 20 is provided so as to completely surround the lead wire 10, and is thermally bonded to the lead wire 10 and the waterproof lid 5.

Here, the respective materials of the lead wire 10 and the elastomer 20 will be described. The waterproof lid 5 is formed of ABS resin, PC resin, PBT resin or the like as in the conventional case.
As a material for the lead wire 10 and the elastomer 20, it is conceivable that the coating layer of the lead wire 10 is formed of PE (polyethylene), and the elastomer 20 is an olefin-based elastomer 20. In this case, since the hard phase of the olefin-based elastomer 20 is polypropylene or polyethylene, the compatibility of the coating layer of the lead wire 10 and the elastomer 20 is good, and the two are thermally bonded to each other. Watertightness can be ensured. Further, in this case, the compatibility in thermal bonding between the olefin elastomer 20 and the waterproof lid 5 made of ABS resin or the like is also good.

Therefore, the thermal bonding between the lead wire 10 and the elastomer 20 and between the elastomer 20 and the waterproof lid 5 can be performed satisfactorily, ensuring watertightness between them, and waterproofing the entire fire alarm system. Can increase the sex.
Further, when the elastomer 20 is arranged between the lead wire 10 and the waterproof lid 5 in this way, the elastomer 20 has a high elastic force, so that the lead wire 10 is bent by an external force. In addition, the elastomer 20 functions as a cushion and absorbs the load applied to the lead wire 10 and prevents the lead wire 10 from being damaged.

Next, a method for manufacturing a waterproof structure using such an elastomer 20 will be described.
As this method, there are three methods.
The first method is a method in which the elastomer 20 is fixed to the periphery of the lead wire 10 by heat bonding or potting, and then the lead wire 10 with the elastomer 20 is insert-molded into the waterproof lid 5.
The second method includes a method in which the elastomer 20 and the waterproof lid 5 are double-molded, and the lead wire 10 is insert-molded inside the elastomer 20.
As a third method, the lead wire 10, the elastomer 20, and the waterproof lid 5 are each formed in an arbitrary process, and after these are assembled automatically or manually, the elastomer 20 is heated to thereby lead the lead wire. 10 and the waterproof lid 5 can be thermally bonded.

(Other embodiments)
Although the embodiments of the present invention have been described so far, the present invention can be applied to various different embodiments in addition to the above-described embodiments within the scope of the technical idea described in the claims. May be implemented.
For example, the shape of the waterproof lid 5 and the number of lead wires 10 are not limited to those shown in the drawing, and can be arbitrarily changed. For example, when it is necessary to penetrate a plurality of lead wires 10 through the waterproof lid 5, each lead wire 10 may be individually provided with the elastomer 20, or the plurality of lead wires 10 may be collectively provided with the elastomer 20. May be.

(Appendix)
The waterproof structure of the fire alarm system described in appendix 1 includes a waterproof part that forms a waterproof area of the fire alarm system, a lead wire that passes through the waterproof part and is drawn into the waterproof area, and the waterproof part. It is characterized by comprising an elastomer interposed between the lead wire and thermally bonded to the waterproof portion and the lead wire.

  According to this structure, heat bonding between the lead wire and the elastomer and between the elastomer and the waterproof part can be performed satisfactorily, ensuring water tightness between them, and waterproofing the entire fire alarm equipment. Can increase the sex. In particular, since this structure can be formed in a short time by general insert molding, the production efficiency can be maintained and the equipment cost is not increased. In addition, when an elastomer is disposed between the lead wire and the waterproof portion in this way, the elastomer has a high elastic force, so that the elastomer is cushioned even when the lead wire is bent by an external force. It fulfills the function and absorbs the weight applied to the lead wire and can prevent the lead wire from being damaged.

  Further, the waterproof structure of the fire alarm system described in appendix 2 is the waterproof structure of the fire alarm system described in appendix 1, wherein the lead wire coating layer is formed of polyethylene, and the elastomer is an olefin-based elastomer. It is characterized by being.

  This more specifically shows an example of the material of the lead wire and the elastomer. According to this structure, since the hard phase of the olefin-based elastomer is polypropylene or polyethylene, the compatibility of the coating layer of the lead wire and the elastomer is good, and when both are thermally bonded to each other, Watertightness can be ensured.

1 Heat sensor 2 Case
3 Thermistor
4 Printed circuit board
5 Waterproof lid
7 Waterproof area 10 Lead wire 20 Elastomer

Claims (1)

A method of manufacturing a heat sensor, wherein the lead wire is drawn into the waterproof region by passing the lead wire through an elastomer through a waterproof part that forms a waterproof region of the heat sensor,
Around the lead wire covered with polyethylene, the olefin-based elastomer is fixed by potting,
With respect to the waterproof part formed of ABS resin, PC resin, or PBT resin, the lead wire penetrates the waterproof part and is drawn into the waterproof area with respect to the lead wire to which the elastomer is fixed. And by insert molding so that the elastomer is interposed between the waterproof part and the lead wire,
Thermally bonding the elastomer to each of the waterproof part and the lead wire;
A method of manufacturing a heat sensor.

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