JPH07169622A - Coil assembly for magnetic relay - Google Patents

Abstract

PURPOSE:To maintain high insulation property stably for a long period by suppressing the occurrence of the cracks of a cover for insulation while materializing the remarkable improvement of yield by enabling the injection molding and greatly lessening the breaking of a coil line at the time of injection molding. CONSTITUTION:A cover 10 for insulation, which covers the periphery of the coil section 9 of a coil assembly 2, is made by the injection molding of thermoplastic rein such as LPC in which either fiber-shaped matter such as glass fibers, etc., or granular matter such as talc, etc., is mixed, and which is set to the melt viscosity of 200-500 poise under the condition of 250 deg.C-340 deg.C in molding temperature and 1000sec<-1> in shearing speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic relay coil assembly used for controlling the opening and closing of contacts in various electric devices.

[0002]

2. Description of the Related Art In this type of electromagnetic relay, insulation is required between a coil portion wound around the outer circumference of a coil spool and a contact in order to normally maintain an operating function. Conventionally, (A) a large spatial distance between the coil portion and the contact, (B) an insulating plate such as a resin plate is interposed between the coil portion and the contact, and (C) a coil assembly It is known that the outer peripheral surface of the coil portion in (1) is coated with a thermosetting resin, and (D) the outer peripheral surface of the coil portion in the coil assembly is coated with a thermoplastic resin.

[0003]

However, among the conventional insulating means as described above, (A) and (B) require a large space in the relay, and a miniaturization such as a communication device is required. It is difficult to apply it as a relay for electric equipment. Further, (C) uses a thermosetting resin having poor molding workability, so that it is difficult to adopt injection molding with high productivity, and therefore productivity is poor and it is extremely disadvantageous in terms of cost. On the other hand, (D) is excellent in workability and can easily reduce the size of the entire relay, but because of its high melt viscosity and low fluidity, shearing is required when adopting injection molding with good productivity. It is necessary to increase the speed, which easily causes disconnection or the like in the coil wire of the coil portion during injection molding, which makes it difficult to sufficiently increase the production yield.

The present invention has been made in view of the above circumstances, and it is possible to improve productivity by suppressing disconnection of a coil wire during injection molding and improving yield.
Moreover, it is an object of the present invention to provide a coil assembly for an electromagnetic relay capable of stably maintaining high insulation while achieving miniaturization.

[0005]

In order to achieve the above object, an electromagnetic relay coil assembly according to the present invention has an iron core, a coil terminal and a coil spool, and a coil portion is provided on the outer periphery of the coil spool. At least one of a fibrous substance and a powdery substance is mixed with the insulating coating for coating the outer peripheral surface of the coil portion in the coil assembly formed by winding, and the molding temperature is 250 ° C. to 340 ° C.
The melt viscosity is 2 under conditions of ℃ and shear rate of 1000 sec ^-1.
It is formed by injection molding of a thermoplastic resin of 00 to 500 poise.

The present invention will be described in detail below. Examples of the thermoplastic resin according to the present invention include polybrylene terephthalate (hereinafter referred to as PBT), polyethylene terephthalate (hereinafter referred to as PET), polyamide 66 (hereinafter referred to as PA66), polyphenylene sulfide (hereinafter referred to as PPS). , Thermotropic liquid crystal polymer (hereinafter referred to as LCP), and the like. Among them, low molecular weight type LPC is particularly preferably used.

Examples of the fibrous substance as the filler include glass fiber, carbon fiber, steel fiber, aluminum fiber and the like, and the aspect ratio (length / diameter) thereof is 30-.
Select from the range of 5 to use. Further, examples of the granular material as the filler include talc, silica, calcium carbonate, mica, aluminosilicate, etc., and the average particle size thereof is selected from the range of 10 to 30 μm and used.
These fillers are preferably blended in the range of 5 to 50 wt% by mixing the above fibrous substance or powdery substance or both substances.

The melt viscosity of each of the above-mentioned thermoplastic resins is PBT-270 ° C., PET-300 ° C., PA66-
2 at a heating temperature of 300 ° C., PPS-320 ° C., LPC-320 ° C. and a shear rate of 1000 sec ^−1.
It is set in the range of 00 to 500 poise. By setting such a melt viscosity, it is possible to improve the disconnection yield of the coil portion and to prevent the occurrence of cracks during heating, as is clear from the experimental results described later.

As an embodiment of the present invention, for example, as shown in FIG. 1, a movable block 3 is rotatably supported at the center of the upper surface of a coil assembly 2 housed in a box-shaped base 1, and the box is Application to the coil assembly 2 in the sealed electromagnetic relay 5 in which the case 4 is fitted into the shape base 1 and sealed is conceivable.

The coil assembly 2 in the sealed electromagnetic relay 5 has an iron core 6, a coil terminal 7 and a coil spool 8 made of a resin molded product.
A coil wire is wound around the outer periphery of the primary and secondary coil portions 9 to form an insulating coating 10 for coating the outer peripheral surface of the coil portion 9 of the coil assembly 2 as shown in FIG. , The above fibrous substance or powdery substance or both are blended, and the molding temperature is 250 ° C.
It is molded by injection molding of a thermoplastic resin whose melt viscosity is set to 200 to 500 poise under conditions of ˜340 ° C. and a shear rate of 1000 sec ⁻¹ .

[0011]

EXAMPLES Next, examples of the present invention will be specifically described, but it goes without saying that the present invention is not limited to the examples. Example 1: As a filler, 30% by weight of glass fiber alone having an aspect ratio of 20 was blended, and by injection molding of LCP having a melt viscosity set to 300 poise under conditions of a molding temperature of 320 ° C. and a shear rate of 1000 sec ^−1. Insulation cover 10
To form. The coil wire of the coil portion 9 had a diameter of 23 μm. Example 2: 40% by weight of talc simple substance having an average particle size of 30 μm was mixed as a filler, and the melt viscosity was set to 400 poise under a molding temperature of 320 ° C. and a shear rate of 1000 sec ⁻¹ by injection molding of LCP. The insulating cover 10 is formed. Comparative Example: 30% by weight of glass fiber alone having an aspect ratio of 10 was blended as a filler, and insulation was performed by injection molding of LCP whose melt viscosity was set to 650 poise under conditions of a molding temperature of 320 ° C. and a shear rate of 1000 sec ^−1. The covering body 10 is formed. In each of Examples 1 and 2 and Comparative Example, the coil wire of the coil portion 9 had a diameter of 23 μm.

With respect to each of Examples 1 and 2 and Comparative Example described above, the disconnection yield (%) during injection molding and 25
When an experiment was conducted to determine whether or not cracks were generated during heating at 0 ° C. × 5 minutes × 3 cycles, the results shown in FIG. 3 were obtained. As is clear from the results of this experiment, in the case of the comparative example having a high melt viscosity of 650 poise, the disconnection yield of the coil wire of the coil part 9 during injection molding was low, and not only the productivity was poor but also the insulation by heating. Cracks easily occur in the covering body 10 and the insulating property cannot be stably maintained for a long period of time.

On the other hand, in the case of Examples 1 and 2 of the present invention, the melt viscosity is as low as 300 or 400 poise and the fluidity is high, so that the breakage of the coil wire during injection molding is very small and the yield is remarkably high. Not only can you improve
Cracks do not occur in the insulating cover 10 due to heating, and high insulation can be stably maintained for a long period of time.

[0014]

As described above, in the coil assembly for an electromagnetic relay according to the present invention, at least one of a fibrous substance and a powdery substance is used as the molding resin for the insulating coating for coating the outer peripheral surface of the coil portion. One is blended, molding temperature 25
By using a highly fluid thermoplastic resin having a melt viscosity in the range of 200 to 500 poise under conditions of 0 ° C to 340 ° C and a shear rate of 1000 sec ^-1 , injection molding can be performed with good workability. The breakage rate of the coil wire at that time can be reduced, the yield can be improved, the productivity can be remarkably improved, and the cost can be reduced. Also,
Since there are few disconnections, it is possible to use a coil wire with a small diameter, and it is possible to increase the ampere turn of the coil and improve the electromagnetic force, that is, the operation performance as a relay. .

Moreover, by mixing a fibrous substance and / or a granular material as the resin filler, the mechanical strength is increased, and the elastic modulus is appropriately set by adjusting the blending amount and blending ratio of the filler. Therefore, it is possible to sufficiently absorb the thermal expansion at the time of heating or the like and prevent the insulating coating from cracking, and it is possible to stably maintain a predetermined insulating property for a long period of time. Further, since it is not necessary to provide an extra space inside the relay, the entire relay can be downsized, and it can be applied to a small device such as a communication device.

In particular, when LPC is used as the thermoplastic resin for molding the insulating cover, the melt viscosity is lowered without increasing the shearing rate to reduce the wire wire breakage rate and crack resistance. Can be promoted.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a sealed relay which is an example of an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of a main part of the present invention.

FIG. 3 is a table showing experimental results for Examples 1 and 2 of the present invention and a comparative example.

[Explanation of symbols]

 2 Coil assembly 5 Sealed electromagnetic relay 6 Iron core 7 Coil terminal 8 Coil spool 9 Coil part 10 Insulation cover

Claims (2)

[Claims] 1. An insulating coating for coating an outer peripheral surface of the coil portion in a coil assembly having an iron core, a coil terminal, and a coil spool, and a coil portion wound around the outer periphery of the coil spool. , At least one of a fibrous substance and a powdery substance is blended, and injection molding of a thermoplastic resin having a melt viscosity of 200 to 500 poise under conditions of a molding temperature of 250 ° C. to 340 ° C. and a shear rate of 1000 sec ⁻¹ . A coil assembly for an electromagnetic relay characterized by being formed. 2. A coil assembly for an electromagnetic relay according to claim 1, wherein a thermotropic liquid crystal polymer is used as the thermoplastic resin.